-------
iTTfl r«m j L»rtI rt
BALTIMORE. MARYLAND
Hourly Values
5,000
1,500
1,000
CARBON MONOXIDE
Figure 2. Hourly PAMS CO Data from Baltimore
-------
BALTIMORE PAMS DATA 1993
SPECIES AND PERCENT OF TNMOC
2 2.3
ACTYL
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Figure 3. ScaMer-plot Matrix - Baltimre PAMS Data
-------
SESSION 6:
SOURCE SAMPLING
-------
Intentionally Blank Page
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SAMPLING AND ANALYSIS INFORMATION AIDS
FOR STATIONARY SOURCE PERSONNEL
Merrill D. Jackson and Larry 1). Johnson
Atmospheric Research and Exposure Assessment Laboratory
U. S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
ABSTRACT
The Environmental Protection Agency, in developing and evaluating sampling and analysis
methodology for stationary sources, has compiled information on availability and applicability of
sampling and analytical methods. Information has also been summarized on the applicability of the
gas cliromatography/mass spectrometry as the analytical method. All of this information is accessible
in three documents: "Stationary Source Sampling and Analysis Directory, Version 2" (SSSADIR),
"Handbook of GC7MS Data and Information for Selected Clean Air Act Amendments Compounds"
(Handbook), and "Literature Review of CAAA Compounds" (LitRcv). The SSSADIR has
information on which sampling and analytical methods to use for organic compounds listed in Title
III of the Clean Air Act Amendments (CAAA) of 1990, as well as Appendices VIII and IX of RCRA
compounds, and the status of method evaluation for these analytcs. The Handbook provides
information on the mass spectra of selected CAAA analytes, primary quantitation ions, relative
retention times and compatibility of the organic compounds in solution. The LitRev provides
information oil CAAA compounds for which EPA has no potential methods available but provides
suggestions on ways to develop methods.
INTRODUCTION
The Source Methods Research Branch, Atmospheric Research and Exposure Assessment
Laboratory, US Environmental Protection Agency, while evaluating stationary source sampling and
analytical methodology for use in conjunction with the hazardous waste incineration regulations
Appendices VIII and IX, RCRA) and the Clean Air Act Amendments, Title III, 1990', has assembled
information on all the compounds listed. Some compounds have validated methods available, some
have methods that might work, and others have no method available at this time. This base of
information has been gathered into three EPA reports. These reports arc:
1. Stationary Source Sampling and Analysis Directory. Version 22 (SSSADIR)
2. Handbook of GC/'MS Data and Information for Selected Clean Air Act Amendments
Compounds^ (Handbook)
3. Literature Review of CAAA Compounds4 (LitRev)
The contents of each of these information aids are discussed below.
SSSADIR
Most databases of sampling and analytical methods are analvte-based. If a method has a
specific list of analytes to which that method is applicable, the database can readily locate all
315
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methods which are applicable for that aiialvte. However, many sampling and analytical methods for
stationary sources do not incorporate a specific list of applicable analytes. These methods (such as
Method 0030)! include only some general guidance (e.g., a boiling point range) on the anahtes
which should be amenable to the method. In an analyte-based database, it is impossible to find out
that Method 0030 is the method of choice for sampling and analysis of carbon tetracliloride in
stationary sources. The Stationary Source Sampling and Analysis Directory (SSSADIR), a database
stand alone program that can be run on any personal computer, provides a solution to the problem of
locating appropriate stationary source sampling and analytical methods for specific analytes. This
version of SSSADIR replaces the "POHCs Directory. Version I"'. The original POHCs Directory
contained only the compounds listed in Appendix VIII'. The SSSADIR has retained all these
compounds, edited and upgraded to incorporate recent information, and has added ail the compounds
from Appendix IX8 and the compounds listed in Title III Amendments to the Clean Air Act of 1990.
The present directory contains information on properties (e.g., boiling point, melting point,
flammability) for each individual compound listed. If a validated method is available for the
compound, this validated method is listed with the pertinent reference. However, if no method
validation information is available, cither a proposed method is listed or the method is left blank
which says that no method is known at this time. Problems with the sampling or analytical
methodology are listed with suggestions for solutions, if known. Physical properties are provided to
permit comparison of one compound to another compound of known properties (such as
incinerability). The database may be searched by several parameters such as name, CAS number,
boiling point, incinerability index, and problems in sampling or analysis.
The database provides a snapshot of available information at one point in time. Since method
evaluation and method development is an ongoing effort within the Environmental Protection
Agency, new information is constantly becoming available. Future updates to the database will focus
on making information on method evaluation available to provide guidance on selection of methods.
No matter what information is available to suggest that a given compound "should work" using a
specified sampling and analytical methodology, the ultimate test is always provided by an actual field
evaluation of that methodology and compound at a stationary source. Even a successful method
evaluation at a particular stationary source docs not guarantee universal success for the methodology
and analyte at any or every stationary source. However, the guidance available through SSSADIR
can provide a starting point for determining applicable methodology.
HANDBOOK
The ''Handbook of GC/MS Data and Information for Selected Clean Air Act Amendments
Compounds" contains information on all of the Clean Air Act organic compounds that arc
chromalographablc. The total ion chromatograms arc included along with the chromatographic and
mass spcctrometric conditions. A reference mass spectrum is provided and the primary quantitation
ions arc identified. Response factors relative to the appropriate Internal Standards (Method 8270 or
Method 5041 )¦ are provided. The compatibility of compounds in solution is discussed and proposed
compatible mixtures are suggested for standards.
The information contained in the Handbook is useful in the development of analytical
methods. For several of the analytical methods for volatile and semivolatilc organic compounds
(especially Methods 0010 and 0030)!, gas chromatographv/mass spectrometry is the required
analytical method. In developing a sampling and analytical methodology for a given analyte. the
analytical methodology must be developed first. If tlie analyte cannot be analyzed successfully, the
applicability of the sampling methodology cannot be evaluated. It should not be necessary for
several laboratories to demonstrate, individually, that a given analyte is not amenable to the analytical
conditions of Method 8270, if this information can be supplied in a Handbook. Also, the Handbook
316
-------
can be useful in evaluating the applicability of GC/MS methodology. It is a time-consuming process
to generate a GC/MS calibration curve for all of the semivolatile organic compounds listed in Title
III of the CAAA, so there is a tendency to use a standard calibration curve that is already available
in most laboratories (i.e., Method 8270) and identify other semivolatile organic CAAA unalytes as
additional peaks. This procedure is valid only if a given CAAA analyte is amenable to the analytical
methodology, and this information is available from the Handbook. It is very important to know
with confidence if a given analyte is not observed because: 1. it is not present at the stationary source
sampled or 2. the compound could not be analyzed by GC/MS.
IJTRKV
The "Literature Review of CAAA Compounds" deals with the compounds in the Clean Air
Act Amendments where no known methods are presently available and none of the existing methods
are expected to provide an acceptable level of performance. The LitRev incorporates the opinions of
several experts in the field of stationary source sampling and analysis relative to possible approaches
in providing new or revised methodology. Many physical properties are listed for each candidate
compound. Chemical structures arc provided for approximately 100 compounds.
The LitRev provides physical and chemical properties of the analytes in suggesting
appropriate sampling and analytical methodologies. Considering the VOST, for example. Method
0030 provides only a single guideline for application of the methodology: the analyte musl have a
boiling point ilOO^C. Approximately 40-50 of the organic analytes on the Clean Air Act list meet
this requirement, but the 0030 methodology is not successful for all of these analytes. A careful
consideration of the physical and chemical properties of triethylamine, for example, shows a very
high water solubility for this compound. Since the Method 0030 analytical methodology requires the
analytes to be purged from the sorbent tubes through a purge flask containing water, consideration of
the water solubility of triethylamine dictates that analytical system response to this analyte will be
poor, at best, because the analyte will not be purged from the water. In fact, no analytical system
response is obtained. The LitRev incorporates information that may save experimentation in various
laboratories to demonstrate that a given methodology does not work.
CONCLUSIONS
Three sources of information have been prepared by the Source Methods Research Branch,
Atmospheric Research and Exposure Assessment Laboratory, US Environmental Protection Agency
to assist the personnel who perform the stationary source sampling and analysis for compliance with
the Clean Air Act Amendments of 1990, Title III and with the hazardous waste incineration
regulations. The information included in these three sources provides the current knowledge of
hazardous vvaste incineration for each of the compounds listed under Appendices VIII and IX of
RCRA and in the 1990 Amendments to the Clean Air Act, Title III.
RKFKRKNCKS
1. Clean Air Act Amendments, Title III, Public Law 101-549, 1990.
2. Jackson, Merrill and Larry Johnson, Stationary Source Sampling and Analysis Directory,
Version 2, U.S. Environmental Protection Agency, Research I nangle Park, NC. EPA Report (In
Press) 1994.
3. Rice, Joann, Joan Bursey, James McGaughey, Raymond Merrill, Jr., and Donald Harvan.
Handbook of GC/MS Data and Information for Selected Clean Act Amendments Compounds, EPA
Report 600\R-94\021, Feb. 1994.
317
-------
4. Wagoner, Dcnnv, Raymond Merrill, Jr., James McGaughey, and Joan Bursey, Literature
Evaluation of CAAA Compounds, U.S. Environmental Protection Agency, Research Triangle Park,
NC, EPA Report (In press) 1994.
5. Test Methods for Evaluating Solid Waste, Physical'Chemical Methods. SW-846 Manual,
3rd ed. Document No. 955-001-0000001. Available from Superintendent of Documents. U. S.
Government Printing Office, Washington, D.C. November. 19S6.
6. Baughman, K.W., R.I I. James., R.B. Spafford and C.I I. Duffey, Problem POHC
Reference Directory, U.S. Environmental Protection Agency, Research Triangle Park, NC,
EPA/600/6-89/094 (NT1S 91-507749) 1991.
7. U.S. Government Printing Office, Code of Federal Regulations. 40CFR. Part 261,
Appendix VIII, 1990, pp 90-98.
8. U.S. Government Printing Office, Code of Federal Regulations. 40CFR. Part 261,
Appendix IX, 1990, pp 98-117.
DISCI .AIMF.R
The compilation of the information in this document has been partially funded by the United States
Environmental Protection Agency under contract 68-D1-00I0 to Radian Corporation and contract 68-
02-4442 to Southern Research Institute. It has been subjected to Agency review and approved for
publication.
Mention of trade names or commercial products does not constitute endorsement or recommendation
for use.
318
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Ilexavalent Chromium Emissions From Aerospace Operations-A Case Study
Ashok Chaurushia, REA
Northrop Corporation
Aircraft Division
One Northrop Ave., 5785/18
Hawthorne, CA 90250
Charles Bajza
Northrop Corporation
Aircraft Division
One Northrop Ave., 5790/23
Hawthorne, CA 90250
ABSTRACT
Northrop Aircraft Division (NAD) is subject to several air toxic regulations such as EPA SARA
Title 111, California Assembly Bill 2588 (AB2588), and Proposition 65 and is a voluntary participant in
air toxic emissions reduction programs such as the F;PA 33/50 and MERIT Program. To quantify
emissions. NAD initially followed regulatory guidelines which recommend that emission inventories of
air toxics be based on engineering assumptions and conservative emission factors in absence of specific-
source test data. NAD was concerned that Chromium VI emissions from NAD's spray coating and
chemical tank line operations were not representative due to these techniques. More recently, NAD has
relied upon information from its ongoing source testing program to determine emission rates of
Chromium VI. Based on these source test results, NAD revised emission calculations for use in
Chromium VI inventories, impact assessments and control strategies. NAD has been successful in
demonstrating a significant difference between emissions calculated utilizing the source test results and
emissions based on the traditional mass balance using agency suggested methods.
INTRODUCTION
l his paper discusses reportable Chromium VI emission reductions at NAD based on improved
emission information and the application of control technologies on various sources.
During 1989 and 1990, among other facilities in California, NAD was required to prepare Air Toxics
Inventory Plans (ATIPs)'7 and Air Toxics Inventory Reports (ATIRs)1,4 in accordance with AB2588.
At the time, there were not sufficient scientific data or methods available to accurately quantify
Chromium VI emissions from spray coating operations. NAD prioritized spray coating and chromium
conversion coating operations at two facilities for conducting a source test program to establish more
representative emission factors.
Since the emissions of Chromium VI depend on a variety of factors such as configuration of the
source, type of coating, applicator, filter media, and Chromium VI content in the coating; the emission
factors established for NAD sources should only be utilized by similar sources after comparison of the
referenced factors.
NAD utilizes various spray booths and chemical process tanks to apply chromated coatings to
aerospace components. The sources outlined in Table 1 were prime candidates for testing based on
emission rates and the type of operation. The emission factors obtained from source test results for these
candidate sources were extrapolated to similar sources at NAD. The tested sources are indicated in
Table 1.
Y12 Facility
Electrostatic Spray Booths No. 3 & 4 utilize a three-part mixture coating (AKZO 463-0600078,
X515, and TL 1(54; mix ratio 2:2:1). The mixture contains 1.1% of Chromium VI by weight. The
coating is applied by automated electrostatic spray guns with high transfer efficiency (i.e. 92%). One
booth coats the front side of the component and the second booth coats the back side. These booths
contained conventional dry filters with 97% (agency suggested) control efficiency at the time of source
testing. Shortly after the source test, High Efficiency Particulate Air (HEPA) Filters with 99.97%s
control efficiency were retrofitted downstream of the conventional dry filters.
SOURCES
319
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A deoxidizing tank which contains a chromated solution (AMCHEM 7) is used in the tank line at the
Y12 facility. This process is similar to a "carwash" type of operation through which aerospace parts arc
conveyed. The solution is sprayed on the aerospace parts inside the enclosure from both sides with the
excess solution recycled back into the tank.
East Complex
Spray Booth No. 31W is open from two sides. A conveyor passes large Boeing 747 skins through
this booth where a mixture of AKZO 463-0600078 and X515 (mix ratio 1:1) is manually applied with
IIVLP spray guns. This spray booth has wet scrubber controls in a down draft configuration. The
agency suggested control efficiency of such a system is 90%.
Spray Booth No. 2 is equipped with conventional dry filters bank with an agency suggested control
efficiency 97%. The HVLP gun is used to manually apply the coating to aircraft components. Since
NAD is changing the coating from a solvent based coating (DeSoto 515X385D) to a water reducible
coating (Deft 44GN011), separate source tests were conducted during each coating operation.
EMISSION CALCULATION METHODS
Mass Balance
When coatings are applied to a substrate inside a spray booth, the majority of the particles/solids arc
transferred to the substrate surface. However, some particles are transmitted as ovcrspray of which 1)
some drop out onto the floor, and 2) some are captured by the filter media controls with some remaining
fraction emitted through the stack into the atmosphere. In the mass balance emission calculation
method, regulatory agencies did not allow credit for dropout rates in the absence of test data. As a part
of the. source test program, NAD conducted ail experiment at its Y12 facility in the electrostatic booth to
determine the dropout percentage of the Chromium VI particles. The results indicate 22% of the
oversprayed Chromium VI particles dropped out in the booth.
In 1990, NAD conservatively utili7ed and overestimated the Chromium VI emissions in its emission
inventory based upon the following method:
Snrav Booths. Chromium VI emissions1 (lb/year) = Usage X Density X wt% X (1-I'E) X (1-CE)
Where:
Usage usage of cliromated coating, gallons/year
Density = density of chromated coating, lb'gallon
wt% = weight percent of Chromium VI in the chromated coating
TE = transfer efficiency of the spray gun
Electrostatic = 0 92 (92%), HVLP = 0.65 (65%)
CE control efficiency of the filler media
Conventional dry filters = 0.97 (97%), Water scrubber = 0.9 (90%)
Y12 Tank Line. Chromium VI emissions2 (lb/year) = Usage X Density X wt% X (l-TE)
Where:
Usage = usage of chromated solution, gallons/year
Density = density of chromated solution, lb'gallon
wt% = weight percent of Chromium VI in the chromated solution
TE = transfer efficiency of the spray heads 0.98 (98%)
Note: Transfer efficiency is assumed to be 98% since the solution is sprayed through the
sprinkler heads which do not atomize Chromium VI particles and the excess solution is recycled back
into the tank. This assumption was approved by the South Coast Air Quality Management District's
(SCAQMD's) staff.
Source Test
Sprav Booths. As discussed above, various factors affect the particulate emissions. In order to
simplify the emission estimation, NAD conducted source tests on candidate sources at the stack. In the
320
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case of spray booths, the total amount of coating sprayed was measured. Grub samples of the coating
were analyzed for Cluomium VI content. Triplicate samples of stack exhaust gases were collected
during the spray coating operation. The amount of total Chromium was analyzed for each sample. The
total Chromium was considered as Chromium VI per the SCAQMD staffs suggestion.
The emission factor established from the source test results, indirectly included all efficiencies such
as transfer efficiency, dropout rate, and control efficiency of the filter media. A summary of these
source test results is presented in Table 2. The following algorithms were utilized to calculate
Chromium VI emissions based on the source test results:
1) Chromium VI emissions from Y12 Electrostatic Spray Booths No. 3 & 4, East Complex Spray
Booth No. 31W, and East Complex Spray Booth No. 2 with water based coating, lb/year =
(Emission Factor6,'8 ,l, pounds of Chromium VI emission/gallon of mixed coating sprayed.
Table 2) X (gallons of mixed coating sprayed'year)
2) Chromium VI emissions from East Complex Spray Booth No. 2 with solvent based coating,
Ib'year (Emission Factor', pounds of Chromium VI emission/pounds of Cluomium VI sprayed,
Table 2) X [(Usage, gallons, of coating with Chromium Vl/year) X (Density of the coating with
Chromium VI, lb/gallon) X (wt% of Chromium VI in the coating)]. This algorithm is utilized to
calculate Chromium VI emissions from most of the East Complex and West Complex spray
booths with the conventional dry filters and HVLP spray gun.
None of the above algorithms were usefiil for Spray Booths No. 22 & 23 at East Complex and area
sources of Chromium VI at East Complex and West Complex, because of the different applicator,
configuration, and Chromium VI content in the coating. The dropout rate6 of 22% was used in the mass
balance algorithm to estimate Chromium VI emission:
1) Spray Booths No. 22 & 23:
Chromium VI emissions'1 (lb/year)= Usage X Density X wt% X (1 -TE) X (1-CE) X (1 -Dropout)
Where:
Usage = usage of chromated coating, gallons/year
Density = density of chromated coating, lb/gallon
wt% = weight percent of Chromium VI in the chromated coating
TE transfer efficiency of the spray gun
Electrostatic - 0.57 (57%) measured for Booth No. 22 while permitting,
HVLP = 0.65 (65%)
CE = control efficiency of the filter media
Water scrubber 0.9 (90%)
Dropout = Percentage of overspray dropout on the floor = 0.22 (22%)
2) Area Source at East Complex and West Complex:
Chromium VI emissions'1 (lb/year) Usage X Density X wl% X (1 -TE) X (1 -Dropout)
Where:
Usage -= usage of chromated coating, gallons/year
Density density of diromated coating, lb/gallon
\vt% = weight percent of Chromium VI in the chromated coating
TE = transfer efficiency of the spray gun, IIVI. P = 0.65 (65%),
Conventional gun = 0.5 (50%)
Dropout ~ Percentage of overspray dropout on the floor ~ 0.22 (22%)
Chromium VI emissions were calculated using 1991 throughput data and a strategy was developed
for comparison between mass balance and source test method. Also, the same strategy was utilized to
prioritize the installation of retrofit controls on spray booths. Figure 1 shows the comparison of
Chromium VI emissions for East Complex sources and Figure 2 shows the comparison of Chromium VI
emissions for YI2 facility spray booths.
Y12 Tank Line. Since the tank line at Y12 facility maintains a constant concentration of
Chromium VI in the solution and the emission factor established for this process could not be
321
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extrapolated to any other process al HAD, an emission factor was developed which depend? on the
number of operating hours (i.e. pounds of Chromium VI emission/hour). Therefore, in order to calculate
Cliroinium VI emissions, the only v ariable needed is number of operating hours per year.
Chromium VI emissions (lb/year) = Number of operating hours/year X (Emission Factor1', pounds
of Chromium VI emission/hour)
Based on mass balance, Chromium VI emission from the tank line was calculated to be 2.12 lb/year.
After source test, the emission was calculated to be 0.38 lb/year. NAD was able to demonstrate 82%
reduction based upon utilization of source test results.
CONCLUSION
As demonstrated in Figure 1 and Figure 2. due to source test results, NAD has documented
approximately a 90% reduction in Chromium VI emissions frotn spray booth operations where HVLP
guns are used and conventional dry filters are installed for particulate control. For booth No. 22, 23. and
area source, emission factors derived from the source test could not be extrapolated because of
dissimilarities with the tested sources; only the 22% dropout rate measured at Y12 facility was used in
the mass balance emission estimation method lo calculate Cluomium VI emissions. Figure 2 shows that
emissions from electrostatic booths at Y12 are reduced by 96% because of the source test. Spray booth
operations at West Complex have also reali7ed approximately a 90% reduction in Chromium VI
emissions because of the source test on booth No. 2 at East Complex. Figure 1 shows the comparison of
C'liromiuni VI emissions from spray coating operations at East Complex. Figure 2 shows the
comparison of Chromium VI emissions from Y12 electrostatic booths and HVLl' booths. It also shows
the comparison after HF.PA filters installation. After IIP.PA filters. Chromium VI emissions are
practically negligible.
The significant emission reductions may be the result of higher transfer efficiency of the applicator,
dropout rate, and control efficiency of the filter system. Further study is required to determine the
specific cause of the significant difference between mass balance calculations and source test results,
since the transfer efficiency of the applicator and the control efficiency of the filter media were not
measured wliile conducting source tests.
Other similar sources may benefit from this method if the emission factors arc applied after careful
comparison of the source configuration. Chromium VI content in coating, type of applicator, and type of
control. The 22% dropout rate may also be used by other sources depending on the above referenced
comparison.
-------
REFERENCES
1. Northrop Corporation, Aircraft Division; AB25HH Air Toxics Inventory Plans ('A TIPs)\ Radian
Corporation, 1989.
2. Northrop Corporation, Aircraft Division; AB25SS Air Toxics Inventory Flans (A TlPs), Biennial
Updates; Environmental Program Development and Agency Reporting, Northrop Aircraft
Division, 1991.
3. Northrop Corporation, Aircraft Division; AB2588 Air Toxics Inventory Reports (A TJRs); Radian
Corporation, 1990 (Submitted in 1991).
4. Northrop Corporation, Aircraft Division; AB2588 Air Toxics Inventory Reports (ATIRs), Biennial
UpdatesEnvironmental Program Development and Agency Reporting, Northrop Aircraft
Division. 1992 (Revisions submitted in 1993).
5. High Efficiency Particulate Air (HEPA) Filters for the Most Demanding Applications (Absolute
Fillers)', CAM-FARR Catalog, p 4.
6. Northrop Corporation, Aircraft Division: Interim Source. Test Report for the. Electrostatic Paint
Booth at the Y-12 Facility: JMM James M. Montgomery. Consulting Engineers, Inc., 1992.
7. Nortlirop Corporation, Aircraft Division; Source Test Report for the East Complex Spray Paint
Booth U3IW; Montgomery Watson, 1993.
8 Northrop Corporation, Aircraft Division: Source Test Report for Water Reducible Paint at the
East Complex Spray Puint Booth i!2: Montgomery Watson, 1993.
9. Northrop Corporation, Aircraft Division; Source Test Report for Solvent Reducible Paint at the
East Complex Spray Paint Booth #2; Montgomery Watson, 1993.
10. Nortlirop Corporation, Aircraft Division; Source Test Report for the Deoxidizing Tank (fiI4) at
the Y-12 Facility, Montgomery Watson, 1993.
11. South Coast Air Quality Management District Memorandum; Evaluation of Source Test Report.
Northrop Aircraft Division. Y-12 Facility, from Mr. John lliguchi to Mr. Mohsen Nazemi; June
22, 1993.
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Table 1. Candidate sources for source testing.
Facility
Source
Description
Y12
Electrostatic spray booths
no. 3 & 4
Automated, robotic electrostatic spray gun,
conventional dry filters
Y12
Tank line no. 14
Liquid spray similar to "car wash", no
controls
East Complex
Spray booth no. 31W
High Volume Low Pressure (HVL,P) gun,
manual operation, water scrubber
filter/control
East Complex
Spray booth no. 2
HVLP gun, manual operation, dry
filter/control, solvent based coating
I'.ast Complex
Spray booth no. 2
HVLP gun, manual operation, dry
filter/control, water reducible coating
Table 2. Summary of source test results
Source
Emission l-'actor
Source Test Method
Y12 electrostatic spray
booth no. 3 & 4
Y12 tank line no. 14
4.075E-05 pounds of Chromium VI
emission/gallon of mixed coating sprayed
6.63E-04 pounds of Chromium VI
emission/hour
East Complex spray booth 6.75E-04 pounds of Chromium VI
no. 31W emission/ga! Ion of mixed coating sprayed
East Complex spray booth 2.62E-04 pounds of Chromium VI
no. 2 with water reducible emission/gallon of mixed coating sprayed
coating
Hast Complex spray booth 1.09K-03 pounds of Chromium VI
no. 2 with solvent based emission/pounds of Chromium VI sprayed
coating
SC.AQMD Method 205.1
SCAQMD Method 205.1
California Air Resources
Board (CARB) Method
425
California Air Resources
Board (CARB) Method
425
California Air Resources
Board (CARB) Method
425
324
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Figure 1. Bast Complex-Chromium VI emission comparison
6.00-^
A. 90% Reduction!
B 22% Reduction!
Booth Booth Booth Booth Booth Booth Area Booth Booth Booth Booth
31W 2 15 22 23 5 3-55 34 8 3 IK 1<>
I Before Source Test ¦ After Source Test
Figure 2. YI2 Facility-Chromium VI emission comparison
3.50
3.00
2,50
£
S 2.00-
0
1 1.50-
I 1.00
0.50
0.00-i
t
S
A
/
\ /'
/
JA, 90% Reductionl
|B. 96% Reduction!
HVLP
IS Before Source Test B After Source Test
Only
ELECTROSTATIC
I After HEP A Only
I After Source Test c
HEPA
325
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The Use of Canisters/GC-MS and a Portable Gas Chromatograph
to Characterize Emissions from an Air Stripper
Cciatiana M. Figuecoa ar.d Jon L. Bennett
Washington Department of Ecology
Air Quality Program
P.O. Box 47600
Olympia, WA 98504-7600
Abstract
Demonstrating and maintaining removal efficiencies for various volatile organic
compounds (VCCs! in an air stripper/carbon adsorption system would ideally be done
through continuous real-tine monitoring. However, especially for state funded
cleanup operations, cost considerations and timeliness of decisions become the
overriding factors. Method TO-14, consisting of whole air samples obtained in
stainless steel canisters shipped for GC-MS analysis, is the conventional method to
specials and quantitate VOCs at the sub-parts per billion levels found in the carbon
adsorption system outlet. Unfortunately, ir.ethod TO-14 does not provide real time
information, and can be expensive. This paper summarizes the results obtained from
using both method TO-14 and a portable gas chromatograph with a photoionizatior.
detector to characterize emissions from an air-stripper/carbon adsorption system.
Field experience indicates that a combination of both methods can achieve the
desired results at a reasonable cost.
Zntroduction
The Washington State Department of Ecology, Toxic Cleanup Program is conducting one
cf its largest cleanup operations consisting of chromium-contaminated groundwater
that threatens the City of Vancouver 's drinking water aquifer. Water analysis
revealed VOCs, presumably originating at a neighboring specialty gas facility, at
levels which the city's wastewater treatment plant would not accept. An air
stripper was installed to remove the VOCs present in the chromium-treated stream.
An air permit was needed to operate the air stripper. A carbon adsorption syste-
was determined to be the best available control technology. The Toxics Cleanup
Program requested assistance from the Air Quality Program in gathering process air
data from the air stripper and carbon adsorption system to obtain that permit.
Trichloroethylene (TCE) was present in water samples at the highest concentration
(150 ppb-4.1 ppir.) . TCE , a carcinogen, has one of the lowest acceptable source
irpact levels (ASIL) in air (130 parts per trillion), therefore it was flagged as
the main VOC of concern froir. this site. The ASIL is an incremental fenceline nu-.ber
used to screen proposed releases of toxic air pollutants.
The Air Quality Program gathered TCE and VOC data through GC-XS analysis of whole
air samples obtained in evacuated passivated canisters, and with a portable gas
chromatograph (PGC!. Berkley et. al. (1) have conducted a comparison of both
methods under arhient applications only. Their work suggests "that the PGC can
produce valid estimates of ambient background concentrations. The work conducted
here subjected the PGC to field performance as a source test instrument, at levels
varying from parts per trillion to parts per million.
Methods
Near real-time analysis of trichloroethylene was conducted using a portable gas
chroiratograph (Photovac 10S70) . Instrument operating parameters were as follows:
the carrier gas was ultra zero air (<0.1 ppm hydrocarbon) with a flow rate of 10
ml/ir.in at 40 PSIG. rhe column is a dimethyl polysiloxsne (CPSil5-Chrompak)
capillary, wall-coated type 2 jidf (0.53 m ID X 10 m) operated at 50 C. The
instrument is equipped with a single chamber photoionization detector consisting of
an electrodeless discharge tube excited with a radio frequency source producing 10.6
electron volts as described by Barker and Leveson (2!. Sample volume was 500 pL
(0.5 ml) and was introduced to the GC by direct syringe injection. The window for
retention time peak identification was set at plus or minus 5% initially, and at
326
-------
plus or minus 10% for the last set of data collected. The minimum peak area was
set to 5 nV-seconds.
Calibration standards for the PC3C wore prepared ranging from 0.26 ppb to 7.4 ppm.
Standard preparation was conducted through dilution of saturated headspace vapor
above pure reagent-grade TCE liquid injected into Tedlar bags containing one liter
of ultra zero air. This rr.ethod is used in hazardous waste site surveying (3) and
published in a technical bulletin (4). The PGC was also challenged with a
certified, independent standard (Scott Specialty Gases) at 1.21 ppir, TCE level.
Initially only PGC measurements were conducted. Subsequently, six-liter passivated
canisters (STS) were used to obtain grab samples from the ducts in and out of the
carbon adsorption system. PGC measurements were conducted before and after the
canister grab sair.ples were collected to compare the values obtained through both
rr.ethods. All canisters were analyzed for 41 compounds by GC-MS (Performance
Analytical Laboratory) in accordance with EPA Method TO-14 (5). USEFA/Department of
Ecology Environmental Investigations Laboratory at Manchester performed quality
assurance review of blanks, calibration curves, surrogate recoveries, n-ass ratios
ar.d quantitation submitted by the contractor.
Air Stripper/Carbon Adsorption System Description and Sampling
An air stripping column (0.76 m ID X 6.7 m high) removes VOCs from the effluent of
the chromium treatment system. The off-gas from the air stripper is blown through a
manifold into five granular activated carbon units arranged in parallel. A sixth
carbon unit is connected in series to the manifold outlet oi the other five units.
The gas exits into the atmosphere after passing through the sixth unit.
The trichloroethylene concentration into the carbon adsorption tanks varies widely
depending primarily on the wells being pumped for treatment. Concentrations ir.
water vary from 160 ppb to 4.1 ppm. This results in calculated carbon adsorption
tank inlet trichloroethylene concentrations ranging from 250 ppb to 6.3 ppm.
Samples from the carbon adsorption inlet and outlet were collected at three sampling
point3. One of the sampling points is located in the air stripper outlet duct that
feeds the activated carbon tar.ks. The other sampling points are at the stack and at
the manifold outlet of the five carbon tanks. Stack and duct velocities and
volumetric flowrates were determined using 'JSfciPA Method 2 !6) .
The data gathered provided adequate information to secure the air penr.j t. Further
canister sampling to ensure compliance with the permit was accomplished through a
contract (5AIC).
Results and Discussion
Out of the forty-one TO-14 compounds analyzed, six were present in the inlet at.
concentrations above 50 ppb. These six compounds were also identified previously in
water analysis of the inlet stream to the air stripper. Table 1 contains the data
gathered on these six compounds, and the removal efficiency achieved by the system.
The TCE outlet concentrations were found to be below the detection limit for the GC-
XS, and in the part per trillion level for the PCC. Table 2 contains a comparison
of the results obtained through both methods. Note that the samples were not-
obtained simultaneously. The detection limits for the GC-MS analysis were
calculated to be 0.5 ar.d 0.1 ppb, both are within the range measured by the PGC. It
appears that the PGC/PID exhibited more sensitivity to TCE than GC-MS. If the PGC
measured concentrations are true, the GC-MS analysis should have revealed at least
trace levels. If the reported detect.ion limits for the GC-MS analysis are correct.,
the PGC could be reporting false positives. Another question that arises is the
suitability of the calibration standards used for the PGC in the parts per trillion
level. Certified calibrations in the parts per trillion level are not yet readily
comrsercially available. It is possible that the calibration gas used for the PGC
was off by a few hundred parts per trillion.
The above discussion highlights the need for the sampling team to determine what
degree of accuracy is necessary for the task at hand. In this case, the measured
values were needed to calculate removal efficiencies, and plus or minus one part per
327
-------
billion is probably an adequate uncertainty limit. At high inlet concentrations
that translates to the difference between 99.97% and 99.58%, at the lowest inlet
concentrations it is the difference between 99.2% and 99.6% removal efficiencies.
The percent; difference between the PCC and TO-14 wan 75% for the in'ct sample. This
difference is large, but expected because the appropriate range of FCC standard was
not available ir. the field that day. As shown in table 2, the calibration
concentration used for the PGC for the inlet samples was 260 ppb, but the
chromatograms resulting after injection of the inler. sarr.ple were ful 1 scale, and
slightly "topped off".
No interfering peaks were noticed in the PGC chromatograns. Retention time
stability was good during each individual sampling set (the coefficient of variation
ranged from 0.5% - 1.99%); however as seen in table 3. the mean retention time did
shift between sets. The shift could be due to unexplained changes in oven
temperature. Unfortunately, the PGC ir.cdel used for this study does not measure oven
temperature.
An apparent false positive was obtained in the September 1953 canister sampling for
compliance testing. PGC measurements were r.ot taken that day. Methylene chloride
ar.d trichlorofluoromethane were found in higher concentrations in the outlet than
the inlet, indicating either external sample contamination or evolution from the
carbon tanks of these compounds. The water analysis did not show methylene chloride
coming into the air stripper at all. These data lead to an exceedance of the permit
conditions. Could this mean improperly regenerated carbon? Although the laboratory
blanks did not indicate contamination, without canister field blanks or field
duplicates it is hard to determine the source of the levels encountered. Weeks
later, when the results arrived, the carbon had already been changed so carbor.
samples were not available to analyze for the above compounds. This experience
points out that it is very useful to have two different analytical tools to double
check each other, especially when field blanks or field duplicates were not taker;
due to cost considerations.
The cost per sar.ple for methed TO-14 is $530, including analysis, canister rental,
and quality assurance review. The cost per each PGC run to the Air Quality Program
war, approximately $100. The PGC cost per sar.ple was calculated by surr.ir.g up the
capital cost incurred in equipment purchasing, personnel training, and dividing by
the total amount of samples analyzed with it to date.
Conclusions
This project served to highlight the strengths and weaknesses associated with both a
field PGC and ir.ethod TO-14. The portable gas chromatograph was capable of
quar.titating trichloroethylene, for the purpose of determining removal efficiencies,
within an adequate uncertainty interval. Laboratory preparation is essential before
the trip. Transporting to the field duplicate standards at each expected range is
recommended to ensure appropriate quantitation. Standard preparation in the parts
per trillion level is the task with the lowest degree of confidence that needs to be
accomplished for use of the PGC. Certified standards at those levels are r.ot yet
commercially available. The advantage of near real time response of the PGC can r.ot
be underestimated. In this case, the ability to obtain data right away served to
assure the permitting agency of the control technology effectiveness, and helped to
expedite the permit.
Method TO-14 is the method of choice to obtain multi-parair.ater VOC infornation with
reliable precision and accuracy. However, it is extremely inportant to ensure that
the sampling budget allows for canister field duplicates and field blanks during
every sampling exercise. The lack of such leads to incomplete data which renders
the data gathered less useful, ar.d, as in this case, may lead to a perceived
exceedance of permit conditions.
The cost of method TO-14 is approximately five times higher per sample than the use
of PGC. Once the PGC has proven adequate, when compared :o ir.ethod TO-14, at the
levels Er.d parameters it is challenged with, its use in combination with occasional
canister samples, car. result in useful data at less cost. Both methods can be
subject to positive (and negative) interferences; therefore, utilizing both methods
provides more clues to ascertain the accuracy of the data obtained.
328
-------
Acknowledgements
The authors would like to acknowledge Mary Beth Hayes, Kimberly Hayden and Joyce
Austin who peer reviewed this paper, and Mohsen Kourehdar who participated ir. this
project.
Disclaimer: Mention of trade names, ccrr.-r.ercial products, contract laboratories or
consulting firms does not constitute endorsement or recor.ner.dation for ur.e.
References
1. Berkley, R.E., Varns, J.L., Pleil, J.; Comparison of Portable Gas Chromatographs
an a Fassivated Canisters for Field Sampling Airborne Toxic Organic Vapors in USA and
USSR; US Environmental Protection. Agency: Research Triangle Park, 193S
2. Barker, N.J.; Leveson, 3.C. American T.aboral ory, Deccirber 19K0
3. Clay, ?.F.; Spittler, T.M. "Tho Use of Portable Instruments in Hazardous Waste
Site Characterizations," in Proceedings of the National Conference on Management of
Uncontrolled Hazardous Waste Sites, HMCRI: Silver Spring, K2.1S85; pp 40-44
4. Calculated Headspace Volumes for Preparation of Vapor Standards Using Pure
Chemicals; Technical Bulletin 21, Photovac, Inc., Deer Park, NY 1990
5. Winberry, W.T., Jr., Murphy, N.T. and Riggin, R.X.; Compendium of Methods for the
Determination of Toxic Organic Compounds in AirJzient Air, EPA-60C-4-C4-041; U.S.
Environmental Protection Agency: Research Triangle Park, 1988
6. Code of Federal Regulations, Chapter 40, Part 60, Appendix A, Method 2
Table 1. Canicter/GC-MS Data and Calculated Removal Efficiencies
I Compound
Inlet
(ppb)
Stack
(ppb)
Before final
carbon tank
(ppb)
Percent
Removal
Efficiency
acetone
53 J
nd
r.d
100
trichlorof luoror.ethar.e
1500
180
290 J
88.2
j cis-1,2 dichloroethylene
57 J
nd
nd
103
I 1,1,1 trichloroethane
25 J
17
0.11 J
63.5
trichloroethylene
5500 J
r.d
nd
99.99
tetrachloroethylene
3CC J
0.19 J
:id
99.96
The J qualifier signifies that the compound was detected at a concentration belov;
the calibration curve range.
-------
Tiible 2. Trichl oroo-.hylene Concentrations Xnasured with the PGC and TO-14
Sdir.pl e
Date
c.a 1 ibrat i or.
Concontrat i on
(PFB!
Meat". 0- PGC
Measured
Concentration
(PPB)
Mean o£ TO-:4 |
Measured ;
Concentration
-------
Improvements in Preparation of Samples Generated
by SW-846 Me thud 0010
Merrill D Jackson, l.arry D Johnson
Methods Research and Development Division
Atmospheric Research and Exposure Assessment Laboratory
US Environmental Protection Agency
Research Triangle Park, \C 27711
James F McGaughey, Denny E Wagoner, Joan T Bursey. Raymond G Merrill
Radian Corporation
P.O. Box 13000
Research Triangle Park, \C 27709
A field evaluation study for SW-846 Method 0010 was conducted at a stationary source emission site
with a high moisture content. The recovery of the dynamically spiked analytes and the spikes added
before the laboratory preparation of the XAD-2® resin were low. The sampling train media had been
prepared according to Method 0010 protocol, so the laboratory procedures were examined in detail
for sources of error. The XAD-2®, wet because of the source matrix, was difficult to fully remove
from the glass trap using only methylene chloride. Because Method 0010 does not specify the solvent
to use for trap rinsing, and since the probe was washed in the field with a 50:50 mixture of
methylene chloride and methanol, this mixture was used to transfer the XAD-2© from the trap to the
Soxhlet extractor. The low recoveries were attributed to the presence of the methanol in the final
extract. (The methanol is removed from the probe rinses during the laboratory sample preparation
process.) A proposed method will be presented that permits the physical removal of wet XAD-2®
from the sampling trap without the use of methanol and an alternate procedure is provided for
removal of methanol from the trap rinse before sample extract concentration.
IMRODIK'IION
A field study was performed using dynamic spiking techniques to evaluate the performance of
SW-846 Method 0010 (Modified Method 5 Train) for sampling and Method 8270 (GC/MS with
capillary column) for the analysis of semivolatile halogenated organic compounds listed in the (.'lean
Air Act Amendments of 1990, Title 111. Using the guidelines of EPA Method 301quadruple
Method 0010 sampling trains with four collocated probes were used. Dynamic spiking equipment
and procedures had been developed and evaluated to allow dynamic spiking of a methylene chloride
solution of the compounds of interest for the duration of each Method 0010 sampling run.2 Two
trains were spiked and two trains were unspiked during each run.
EXPERIMENTAL
The field evaluation study was conducted at a facility where waste chemicals were incinerated in
a coat-fired boiler. A "hiosludce" consisting of 10 percent organic matter and 90 percent water was
led continually to the incinerator. A site presurvey showed that none of the proposed analytes was
present and there was approximately 10 percent moisture in the background emissions. Method 0010
sampling trains were recovered in the field, and components were shipped to the laboratory for
preparation and analysis. Methylene chloride extracts were generated of the following train
components: I. Filter/front half rinse, 2. XAD-2® sampling module and Condensate/condensate rinse.
The final volume for these sampling train components was 5 ml., rather than the 1 rnL final volume
specified by Method 8270.
-------
RESULTS AND DISCUSION
Results for the GC/MS analysis are summarized in Table I. Eight sampling runs using quadruple
trains had been performed in the field; acceptable results were obtained for only four runs (1,2,3,6).
I'or those four runs, most compounds results were generally comparable to laboratory and field
results.2,3 However, results from other sampling runs showed very low recoveries for the surrogate
compounds and many of the spiked compounds were not detected.
Table I
Summary of Results for All Eight Runs and All Sampling Trains.
Using Surrogate-Corrected Data
Run
Train A
Spiked
Spiked
Train C
Uuspiked
Unspikcd
:i: M'-
hMrX '
C
¦ ^ 3
1
y
>'
y
y
y
y
y
y
y
y
y
y
2
y
y
y
y
y
y
y
y
V
r.
y
y
3
y
y
y
y
y
V
y
y
y
y
y
y
4
n
y
n
n
y
n
>
y
n
y
y
V
5
7.
y
y
7.
V
n
y
y
y
>
y
V
6
V
y
n
y
n
n
Z
y
y
z
y
V
7
n
n
n
y
y
y
Z
y
z
y
y
z
8
n
y
I
y
y
y
z
y
y
y
y
Z
Note Recoveries for C and D Trains refer to recoveries of surrogate compounds and Uotopicallv-labelee analogs
X - XAD-2®! module; C - Condensate fraction, F Filter fraction. 7. - Partial success; some but not all anaiytcs
detected, y ~ All analyses detected; n No analytes detected.
Careful examination of the data for all of the sampling runs showed that, in general:
1. Recoveries of the surrogate compounds spiked in the laboratory were low for the XAD-2® where
most of the organic compounds were expected to be retained, 2, Isotopically-labelcd compounds
spiked in the laboratory to track recovery were frequently not observed at all, 3. The majority of the
analytes spiked in the field were not observed, and 4. Recoveries for field-spiked analytes that were
observed ranged from 4 percent to 63 percent.
Since the surrogate compounds and isotopically-lubeled compounds are spiked in the laboratory'
after return of the sampling train components, problems were in the laboratory preparation rather tha
in the field spiking.
The important parameter is recovery of spiked organic compounds from XAD-2® since this
where they are located. Recovery results for these field samples were sufficiently different from
previous recovery results observed from laboratory2 and field studies3 that an explanation for the lov
recoveries was pursued. Quality control results from method blanks (filters, water, solvents,
XAD-2®)were examined. Recoveries from method blanks were acceptable to high, indicating that
general laboratory sample preparation and analysis procedures were done properly.
Method spike (train components spiked with analytes and surrogate compounds in the laboratory
recovery data were also examined. The method spikes arc extracted and analyzed with the field
samples. The results obtained for the XAD-2® method spikes (Table II) are typical; acceptable to
high recoveries indicated that surrogate and sample spiking, preparation, and analysis procedures
were in control.
332
-------
Table 1J
Spiked Compounds and Surrogates Recovered
from Dry Method 0010 XAD-2® Traps
Theoretical
Compound
Amount
% Recovery
Surrogate
(f>&
* MS-A
MSB
> MS-C
WS-D
2-1'luorophenoi
991
107
99
108
102
Phencl-ti,
1010
112
106
113
108
Nitrobeiuene-dj
509
112
95
104
98
2-FJuo-ohiphenyl
¦190
119
i 15
122
111
2,4.6-Tnbromophenol
99?
67
74
73
66
Ierpheny.'-dN
50!
135
112
115
108
k'pid;Jot'<>hyt1rin-ii5
250
99
68
76
71
< .ii)<*robeiizene-d.
350
94
91
106
93
1,1,2.2-TetrachIorotthane-d^
254
114
93
99
91
Dis(ch!orocihv!}cthcr-d?
533
104
91
95
87
Benzyl chloridc-d-
2.14
103
122
130
117
2)4.5-Trid;lnroplifiiol-d,
129
ND
ND
106
ND
Targets
0
-------
using the same spiking solutions and the same procedures. l"he original extracts, which had been
archived after mass spectral analysis, were next examined visually to determine if the appearance of
these extracts was qualitatively or quantitatively different from the appearance of the quality control
samples. Several key differences were observed:
Method blanks and method spikes were light yellow in color and had the appearance of several mL
of clear organic solvent. The color of field sample extracts ranged from clear to nearly brown. Some
of the field extracts were clearly completely aqueous, with only small pools of organic liquid floating
on top. two phases were clearly visible in some of the field extracts; and many of the field samples
were not methylene chloride extracts, since only a slight odor of methylene chloride was detected
when vials were opened.
Laboratory sample preparation procedures and observations were carefully reviewed with
laboratory staff. The observation was reported that many of the field samples required far longer
(3-4 hours) than the usual amount of time (20-30 minutes) to achieve concentration to 5 ml, using
Kuderna-Danish concentration procedures.
The obvious difference between the quality control samples and the field samples was that the
laboratory-generated sampling train media were drx, while the field XAD-2® samples were wet
because of the moisture content of the source. Dry XAD-2® can simply be poured from the
sampling module to the Soxhlet extraction apparatus. Wet XAD-2® does not pour, but sticks to the
glass walls of the sampling module and is not readily moved from the sampling module with
methylene chloride rinses. Typical procedures used for the removal of wet XAD-2® from the
sampling module include repeated rinses with methylene chloride, which frequently leaves significant
amounts of the wet XAD-2© in the sampling module, or tapping the sampling module against the
laboratory bench top, which often results in breakage of the sampling module. Laboratory staff had
tapped the XAD-2® from the modules to remove as much as possible, rinsed the walls of the moduli
with methylene chloride, and performed a final rinse of the sampling module with methanol. If a
sufficiently large amount of methanol is present when sample concentration is performed, methylene
chloride will be driven off rather than methanol, and the final extract will consist of a methanol
solution with significant losses of surrogate compounds and analvtes.
The rinses used in the field recovery of Method 0010 train components consist of 50:50
methylene chloride: methanol, which form a homogeneous solution. The methanol can be separated
from the methylene chloride only if sufficient water is added to create two distinct phases. However
100 ml. of methylene chloride can hold up to 15 ml. of water without separating into two distinct
phases. According to the method, sample extracts are dried by filtering through a bed of dry sodiurr
sulfate. If sufficient water is present, the sodium sulfate will cake and will not dry the extract
efficiently. Thus, after drying, if the sodium sulfate cakes, an extract may consist of methylene
chloride, water, and methanol, all in one phase. If a solution of this composition is concentrated,
methylene chloride will be lost before the water and methanol are lost, resulting not only in a
water/methanol solution if sufficient quantities of water and methanol arc present in the original
extract but also in lost of target compounds due to higher concentration temperatures. However, if
sufficient water (50-100 mL) to effect separation of phases is added prior to extraction, the methano
will be driven into the aqueous phase and excellent recoveries of spiked surrogate compounds and
analytes can be obtained.
Laboratory experiments were conducted to reproduce the conditions under which the field
samples had been extracted. Replicate samples of dry XAD-2® were spiked with surrogate
compounds and analytes to provide a baseline for recovery. Excellent recoveries and good
reproducibility were obtained. Next, wet XAD-2® was prepared and spiked with surrogate
compounds and analytes. The 40 g quantity of XAD-2® which is contained in the sampling module
of the Method 0010 train retains approximately 50 mL of water when water is poured through the
resin bed. This 50 mL of retained water does not produce a distinct water layer when the spiked wi
XAD-2® is extracted and analyzed. When the extracts from the wet XAD-2® were concentrated ar
analyzed, recoveries were slightly lower than the recoveries obtained with dry XAD-2® and
334
-------
reproducibility was slightly poorer, but both recovery and reproducibility were acceptable. The wet
XAD-2® was prepared and spiked in the Soxhlet extractor, so no transfer of wet XAD-2 without the use of methanol, using the apparatus
shown in Figure 1. The glass wool is removed from the end of the sampling module and placed in
the Soxhlet extractor to ensure extraction. A small piece of pre-cleaned glass wool is placed in Un-
arm of the Soxhlet extractor to ensure that no XAD-2# enters the side-arm. The sampling module is
inverted (glass frit up) over the Soxhlet extractor, approximately 5-10 ml. of methylene chloride is
added above the glass frit, and air pressure created by squeezing the rubber bulb shown in Figure 1 is
used to gently but firmly push the methylene chloride through the frit, forcing the resin out of the
sampling module. This process is repeated 3 to 5 times, and a Teflon®1 wash bottle containing
methylene chloride is used to rinse the walls of the sampling module to transfer resin which adheres
to the walls of the sampling module. After 3-5 methylene chloride rinses, no more than a monolayer
of XAD-2® usually remains in the sampling module. The glass wool plug is removed from the side
arm of the Soxhlet and added to the Soxhlet. A flowchart for the overall method is shown in
Figure 2. lhis transfer procedure has been used successfully to transfer XAD-2® from sampling
modules used in sampling a source with 55 percent moisture: excellent recoveries of both surrogate
compounds and spiked analytes were obtained. In addition, this procedure is far more efficient than
the procedure of tapping the resin out of the sampling module. Three transfers using the rubber bulb
can be performed in one or two minutes.
The investigation with subsequent laboratory study illustrates (he value of sufficient quality
control data in determining the cause of a problem with data quality. A new procedure for the
preparation of Method 0010 train components for analysis by SW-846 Method 8270 has been written.
In this procedure, the use of methanol in the laboratory is directly and specifically prohibited to
ensure that the final extracts consist of methylene chloride, not a mixture of methylene chloride and
methanol. Also, addition of sufficient water to ensure that two distinct phases are produced when
both water and methanol arc components of the solution (for example, in the sampling train rinses of
the front half and the condensate) is a required part of the procedure. This procedure is currently
being subjected to EPA review.
DISCLAIMER
The information in this document has been funded wholly by the United States Environmental
Protection Agency under contract 68-D1-00I0 to Radian Corporation. It has been subjected to the
Agency's peer review and administrative review, and it has been appiwed lor publication as an EPA
jocument. Mention, of trade names or commercial products does r.ot constitute endorsement or
eeommendation for use.
IEH-RL'NCI-S
.. EPA Method 301. Protocol for the Field Validation of Emission Concentrations from Stationary
Sources. U. S. Environmental Protection Agency. EPA 450/4-90-0015. April, 1991
!. Laboratory Validation of VOST and SemiVOST for Ilalogenatcd Hydrocarbons from the Clean
Air Act Amendments. Volume 1 and 2. EPA 600/R-9 V123 and b. N ITS PB93-227163 and
PB93-227171. U. S. Environmental Protection Agency. July, 1993.
i. Field Test of a Generic Method for Halogenated Hydrocarbons. lil'A 600'R-93/l01. NTIS
PB93-2I2181. U. S. Environmental Protection Agency. June. 1993.
335
-------
\ /
\
\
Rubber f \
Bulb | I
(
Teflon®
Tube
I s MoCyis addfld to XAD-2® Trap Sovirel® r ]
~Z~y Fitting ' 1
=\ ~
v_x
A
Glass
Frit
XAD-2®
^-Glass Wool
f
Soxhlet
-b
Precleaned
Glass
Wool
/ \ Round
i ' Bottom
\ / Flask
Ground Glass '
Ball Joint
)
Figure 1. Transfer of Wet XAD-2®
136
-------
Condensate H?0
(Irrpirge* 1)
(Ccntaner4)
Rirsn of ;rn|)inqe' 1
CH C'„/CH OH
Corroine
t.
Spike wffh Su'rocales ynrl
teotcoically-Labslec: Anaiags j
1
Separatory Funne Extract or
(Acd H2G .f recessary to
secarate chases}
hxlrar;' Water I aynr with
C*™»>CI ^ Ac .is; p.H aid tJr:
Ac.d/Base or Base/Ac.d
bx1racticn
Particulate Matter
Ftttor
(Containsr 1)
J
Scxhlet Fxtraction
ch„c:.
t
' Separate
i CH?C| ?
Extract
r.
j Spike with Surrogates, |
Isotop'calfy-Labe ed
Anuloqs
rrent Half Rinse,
Front half of Filter Holder,
Probe and Nozzle
CI i, Cl^/O f 30H
(Container 2)
1
Hfter, Add Filter to
Paiicjlate Matter F ter
Seoaratcry Funnel
Extraction
(Ada H2O if necessary to
separate phases}
t
Extrac: Watsr Layer with
CHgCip Adjust pH and do
Acid/Base or Base/Acid
Extraction
Ccnb.ne CH: CI ^ Exracts j-
ire will
I
Concentrate to 5mL
T
Analyze by GC/MS
Combine 01l,0?
Extracts j
r
Rrrrove Moistum wrth N
-------
Condensate H20
(impinge 1)
(Conta;ner 4)
Rinse of mpinger 1
CHj Cl2/CH aOH
Particulate Matter
Filter
{Contairwr 1}
Corr.oine
T
I
Spike with Surrogates and
Isotopically-Laheled Ana'ogs
f
Spike with Surrogates,
isotopicsiiy -Labeled
Analogs
Soxhiet Extraction
Seporetory Funrol Extraction
Ci2 Extracts
Separate
CH?Ci
Extract
I Corrbine Cri,C.
Ext'acts
I
Concentrate to 5 ml.
L
' Wi'tl
T
?
;e to
I
i
Remove Moisture with Nc^SO^
f
Analyze by GC/MS
Concentrate to 5ml.
Anaty?e by GC/MS
Front Half Rtrse,
^ror,: Half of F; 'or Holder
Probe and No/zle
Ch^C!2/CH3OH
(Container 2)
, Hilter, Acd Filter tc
I Palicjlate Matter Filter
Separatorv Fmrel
Extraction
(Add if nc:;cssary to
sepa'ate phases]
FxVact Wator layer with
CH^ C: 2; Adjust pH anc do
Acid/Base or Base/Acic
Extraction
i
SaV3CH,CI? Laye-
(BottOTi;
Figure 2. (Continued)
138
-------
EV ALUATION OF GAS CHROMATOGRAPHY DETECTION SYSTEMS FOR
TOTAL GASEOUS NONMETIIANE ORGANIC COMPOUNDS
Stephanie B. Philipp, Dave-Paul Dayton, Raymond G. Merrill
Radian Corporation
P.O. Box 13000
Research Triangle Park. NC 27709
Merrill D. Jackson
Methods Research and Development Division
Atmospheric Research and Exposure Assessment Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
ABSTRACT
The development of an emissions monitoring prototype instrument to provide continuous or
semi-continuous quantitative measurement of total gaseous nonmethane organic carbon (TGNMOC)
emissions from stationary sources will allow for better characterization and control of compounds
under the Clean Air Act Amendments of 1990, Title III. To meet this development goal a search
has been initiated to identify detection systems for TGNMOC that are both simple to use and
accurate. The measurement of oxygenated compounds are of particular interest since many emission
sources may have a large proportion of them. Detection system identification has been
accomplished by conducting a search of detector manufacturers' literature, and talking with
manufacturers' technical personnel Several detector systems, marketed as appropriate for
TGNMOC measurement, have been identified and evaluated in the laboratory. The detection
systems evaluated include a Catalyzed Flame Ionization Detector and a Thermionic Ionization
Detector, both produced by DETector and Engineering Technology, Inc., and an Oxygen Flame
Ionization Detector and an Elemental Analyzer, both produced by Fisons Corporation. The primary
performance goal for the detection systems required that those systems yield equal response for all
organic compounds in a mixture, including oxygenated compounds, based on carbon number. None
of the detection systems evaluated met the primary performance goal of uniformly measuring
organic carbon, regardless of the chemical structure of compounds in the sample. While some
success was realized for many classes of organic compounds, oxygenated compounds presented a
challenge that none of the detection systems could master.
INTRODUCTION
The primary objective of this effort was to identify an appropriate detection system for
incorporation into a prototype total gaseous nonmethane organic carbon (TGNMOC) emissions
nonitoring instrument. The accurate measurement of TGNMOC is critical to the characterization of
many industrial processes.
Although the flame ionization detector (FID) has been used as a universal detector for
:oinplcx mixtures of organic compounds, compounds containing heteroatoms have been shown to
,-ield lower response than straight chain aliphatic hydrocarbons,1 giving an underestimate of organic
:arbon The Catalyzed Flame Ionization Detector (CFID) produced by Dl-Tector Engineering and
Technology. Inc. (Walnut Creek, CA) is marketed as a detection system that provides enhanced
esponses for hetcroatom compounds The CFID is a combination ignitor, polarizer, and catalytic
;ourcc made of nickel/aluminum oxide-coated ceramic. Ionization is achieved with a hydrogen/air
lame and all organic compounds are ionized to some extent. The sensitivity of the CFID is
339
-------
controlled by varying the heating current applied to the catalytic source. The higher the current
applied, the greater the source temperature and the greater the sensitivity. The current setting,
thermal conductivity, and flow rates of the carrier gases influence the temperature of the source to
some extent.
The Thermionic Flame Ionization Detector (TID), also produced by DETector Engineering
and Technology, is marketed as an oxygen-selective detector when operated in a nitrogen (N;)
environment. The TID is a heated, alkali-coated ceramic source. Ionization is achieved by the
extraction of an electrical charge from the heated thermionic source, controlled by the surface work
function, the surface temperature and the gas composition surrounding the source surface. The
manufacturer has reported very high specificity and sensitivity to compounds containing
electronegative functional groups from a low work function source operated at temperatures around
300'C in a N, environment.3
The Oxygen-Flame Ionization Detector (O-FID) produced by Fisons Instruments (Danvers,
MA) is marketed as the recommended detection system of the European Economic Community and
the U.S. Environmental Protection Agency (U.S. EPA) for analysis of oxygenated compounds in
gasoline The O-FID is comprised of a cracking reactor, an activated nickel methanizer, and a
standard FID. The cracking reactor is a platinum-rhodium catalyst tube that is heated to about
1200°C. All compounds eluting from a chromatographic column flow through the cracking reactor
and are disintegrated into their individual elements. After disintegration, carbon monoxide (CO) is
formed from elemental carbon and oxygen (02). Any unreacted carbon is deposited on the inside of
the reactor tube. Hydrogen (H,) passes undetected through the methanizer and FID assembly. The
methanizer converts the CO into methane for detection by the FID. The signal produced is
proportional to the O, contents in the sample. With a split rate of 1:80, the O-FID has a detection
limit of 5-10 ppmC with a linear range of three orders of magnitude. The range is limited by the
cracking capacity of the reactor. The cracking capacity depends upon the cracking temperature of
the reactor and the individual type of molecule to be disintegrated, therefore, the cracking
temperature only has to exceed a molecule's reaction temperature threshold to obtain complete
cracking.
Fisons also produces an Elemental Analyzer (EA) marketed as a detection system for
simultaneous carbon, H., N,, and Oj determinations from solid, liquid or gas samples The sample
to be analyzed is injected into a sealed combustion chamber, that is packed with catalytic materials
(i.e., nickel coated carbon) and is maintained at a temperature of around 1060°C. As the sample
enters the combustion chamber, 0; is injected into the helium (He) carrier gas that is flowing
through the chamber. The resulting catalytic oxidation will theoretically assure complete oxidation
of the sample. The combustion gases and N2 arc swept through the reduction reactor and into a
chromatographic column by the He carrier gas. The measured concentration of each compound is
determined by a Thermal Conductivity Detector (TCD) as they elute from the column High
detection limits and detection of methane (CH4) and CO, interfere with this detection systems
application to TGNMOC.
EXPERIMENTAL PROCEDURES
The FID, CFID and TJD were evaluated with liquid standards containing oxygenated and
non-oxygenated compounds as listed in Table 1.
The CFID assembly was installed on the existing FID tower of a Varian 3400 Gas
Chromatograph (GC). Operating conditions of the GC/CFID system are listed in Table 2. The
parameters listed in this table were kept constant throughout the evaluation of the CFID. The
current applied to the CFID source was varied to evaluate the oxygenated compounds responses and
to choose the current setting at which the CFID responded linearly to number of carbons, with the
sensitivity required to meet the project's stationary source sampling goals. An example
chromatogram with identified peaks from the CFID evaluation is shown in Figure 1.
340
-------
Table 1
Response Factors in Area Counts/nmolC for Data Using the
Flame Ionization Detector and the Thermionic Ionization Detector
Analyte
CH1> Response Factor
FID Response Factor
TID Response Factor
Amaldehyde
7324
8696
9415
Methanol
4388
12657
41098
Acexne
6769
20176
7132
2-Butanor.e
6997
15420
7283
Bc-rm-ne
12967
20092
9
Butyl Cellosolve®
76-17
155-18
130705
Bcn?aldchyde
8008
17800
395
llexar.c
*
18316
4134
Heptane
*
13866
3-1520
iso-Octanc
*
23113
8097
Nonanc
*
18502
23918
Mcth>lsiie Oilnnde
*
15401
127274
Triethyliminc
12303
434899
* •¦ Not Analyzed
The TID was installed on the existing PIO tower of a Varian 34(K) GC. Operating conditions
for the optimization and evaluation experiments are listed in Table 2. The TID was optimized and
evaluated for oxygenated compounds by analysis of a liquid standard containing oxygenated
compounds. Liquid standards containing aliphatics, a chlorinated compound, and a substituted
amine were also analyzed under the same operating conditions as the oxygenated compounds.
For comparison, all compounds analyzed by the GC/TID system were also analyzed by a
conventional GC/FID system.
RESULTS
The results from the evaluation studies of the CFID. the FID, and the TID are presented
graphically in Figures 2, 3, and 4, respectively. For comparability, the response factors are stated
in units of area counts per nanomoie of carbon. Nanomoles of carbon arc the moles of analyle
injected onto the GC column multiplied by the number of carbons associated with a molecule of the
analyte. The response factors are plotted against the number of carbons in each compound
analyzed. Table 3 lists each compound analyzed and the number of carbons in each compound.
The average response factor for the detection system represented in each graph was also plotted. In
in ideal situation, the response factor from each specific detector should be the same for each
:ompound, regardless of the number of carbons The horizontal line shown in each graph
-eprcsents the ideal response.
CONCLUSIONS
Five detectors were evaluated for their ability to provide a linear response to organic carbon
:ontents in oxygenated and non-oxygenated organic compounds. The FID and CFID did provide a
inear response to organic carbon content in volatile oxygenated compounds, and
341
-------
Response (mV)
10
o
i n 1111 m 111 n 1 i
10.24
12.65
Oft
o
(B
O
o
o
ro
o
LLLi
111111111111 n 111111111 n 11111111111111111 > 111
ACETALDEH
ACETONE -
IS0PR0PAN -
METHYL ET -
BENZENE -
TOLUENE
ETHYL BEN
BUTOXYETH
BENZALDEH
2.24
5.32
~~ 21.71
22.03
25.58
1
27.B3
28.96
27.08
20.42
-24.42
28.73
33.10
-------
Response Factors vs. Number of Carbons
Catalyzed Flame Ionization Detector
Number of Carbons
-»••• CFID Average RF
Figure 2. Comparison of Measured Response Factors and the
Average Response Factor for the CFFD
343
-------
Response Factors vs. Number of Carbons
Flame Ionization Detector
Number of Carbons
FID
Average RF
Figure 3. Comparison of Measured Response Factors and the
Average Response Factor for the FID
344
-------
Response Factors vs. Number of Carbons
Thermionic Ionization Detector
Number of Carbons
TID Average RF
Figure 4. Comparison of Measured Response Factors and the
Average Response Factor for the TID
345
-------
Table 2
Operating Parameters for Detection Systems Evaluated
Instrument
Varian 3400 GC with FID tower and cryogen capability
Column
J&W DB-624 30 m x 0.53mm Serial #S9516312
CarTier Gas
5.Si mL/min (He) for FID, CFID
4.2 mL/ir.ir. (He) for TID
Detector Gases
(FID, CRD)
Gas ! (Air): 304 mL/min Gas 2 (H;): 30 mL/min
Makeup (He): 30 mL/min
Detector Gases (TID)
Gas 1 (N,): 19.5 ml.,'min Gas 2 (N:): 76.9 mL/min
(subtract carrier gas flow rate)
Temperature Set-points (FID.
1 CFID)
Injector: 2003C Detector: 205°C
Oven: 25°C for 8 min, then ramp @ 4°C/min to 110'C
Temperature Set-points
(TID)
Iniector:200 °C Detector. 320*C (Coniti'.ioi: 3)
Oven: 25°C for 8 min, tiler, ramp @ 4
-------
comparison showed that the response factors for the ketone and the aldehyde were similar to the
response factor for the alcohol.
The O-FID and EA detection systems were not able to analyze gaseous samples containing
oxygenated compounds and were, therefore, not applicable to the measurement of gaseous
TGNMOC. The technical support manager for Fisons stated that the O-FID was only suitable for
analysis of matrices that did not contain a predominant volume of oxygenated species. The detector
was built for analysis of gasoline, consisting of many components with no oik predominant
oxygenated organic compound. An air sample, containing percentage levels of N2, 02, and CO;,
and ppm levels of oxygenated and non-oxygenated organic compounds, would saturate the
methanizer, and cause the detection system to malfunction. As a result, no evaluation samples were
analyzed on this detection system. A gas standard containing oxygenated organic compounds and
benzene was sent to the Fison lab for evaluation of the EA detection system but were not analyzed
because Fisons could not develop an appropriate method for analysis of the gaseous sample.
None of the detectors evaluated met the primary performance goal of universal, linear,
organic carbon response While some success was realized for many classes of organic compounds,
oxygenated compounds presented the strongest challenge to the detection systems evaluated. Within
an individual chemical class, a 1:1 linear carbon response relationship was achieved, but a linear
carbon response relationship was not achieved when comparing one chemical class to another.
These detections are useful for selective applications, but they do not meet the needs of an universal
detector for total carbon in a sample containing a mixture of compounds from various chemical
classes.
DISCLAIMER
The information in this document has been funded wholly by the United States
Environmental Protection Agency under contract 68-D1-0010 to Radian Corporation. It has been
subjected to Agency review and approved for publication. Mention of trade names or commercial
products does not constitute endorsement or recommendation for use.
REFERENCES
1. Skoog, D.A. Principles of Instrumental Analysis. Third edition, Saunders College
Publishing. New York, 1985. p. 767.
2 Patterson, P L. DET Report No. 23, Detector Enginering and Technology, Inc., Walnut
Creek, CA, 1992, p. 10.
347
-------
Sampling of Volatile Organic Compounds From Combustion Sources Using
Tedlar® Bags with Analysis by GC/MS
Rohini Kanniganti, Richard L. Moreno, Joan T. Bursey and Raymond G. Merrill
Radian Corporation, P. O. Box 13000, Research Triangle Park, North Carolina 27709
Robert G. Fuerst, Larry D. Johnson
Atmospheric Research and Exposure Assessment Laboratory
Methods Research and Development Division
Source Methods Research Branch
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
ABSTRACT
A Tedlar® bag method (Draft SW-846 Method 0040) provides a detailed procedure for sampling
volatile organic compounds from gaseous effluent sources such as hazardous waste incinerators. This
method may be applied in situations where SW-846 Method 0030 (VOST) is net applicable such as
highly concentrated (> 1 ppm) or very low boiling (< 303C) compounds. Method 0040 may also be
applied to compounds at high concentration (> 1 ppm) with boiling points < 121 "C. Appropriate
analytes must exhibit a loss in a Tedlar® bag of less than 20% over a 72-hour storage time. Either
constant or proportional sampling may be used depending upon the variability in the emission flow rate.
Gas chromatography/mass spectrometry (GC/MS) is the analytical method of choice. To develop an
accurate and reproducible analytical method, a fixed loop interface to the GC/MS was designed.
Calibration and instrument detection limits were determined for selected analytes. Instrument detection
limits for vinyl chloride and benzene were 0.5 and 1.2 ppm, respectively. Accurate and reproducible
preparation of gaseous standards in Tedlar® bags and dynamic spiking into the sampling train were
demonstrated.
INTRODUCTION
Draft Method 00^0 establishes standardized test conditions and sample handling procedures for
the collection of volatile organic compounds from gaseous effluent sources such as hazardous waste
incinerators by time integrated evacuated Tedlar* bags. Specific guidelines governing the use of Tedlar8
bags for sample collection and storage are also provided in the draft method. The draft Method 0040
sampiing train incorporates a heated particulate filter and a cooled condensate collector and is thus able
to handle complex source streams such as those with high moisture and particulate loading.
The primary application of draft Method 0040 is with highly concentrated (> 1 ppm) or with
very low boiling (< 30 °C) compounds, where Method 0030 is not applicable. Compounds with boiling
points of < 121 °C, present at a concentration below the respective condensation point are also candidate
analytes. Applicable compounds must exhibit a loss in a Tedlar* bag of less than 20% over a 72-hour
storage time. Gas chromatography/mass spectrometry (GC/MS) is the analytical method of choice
because of its unique ability to provide positive identification of compounds in complex mixtures like
stack gas. Draft Method 0040 is not applicable to the collection of samples in areas where there is an
explosion hazard. Isokinetic sampling is not used and therefore the method is not applicable to the
collection of highly water soluble volatile organic compounds contained in an aerosol of water. Either
constant or proportional rate sampling may be used, depending upon the extent of the variability of the
emission flow rate Available stability data suggest that draft Method 0040 may not perform well ir.
sampling streams containing polar and reactive compounds.1 The use of a Tedlar* bag to sample polar,
reactive compounds needs to be evaluated before sampling.
348
-------
EXPERIMENTAL PROCEDURE
Method 0040 Sampling Train: A detailed schematic of the principal components of the
sampling train is shown in Figure 1. A representative sample is drawn by vacuum from a stationary
source through a heated sample probe and filter. The sample then passes into a condenser where the
moisture and condensable components are removed. Gaseous emissions are then collected in a Tedlar*
bag held in a rigid, opaque container which is connected to a control console. The console controls the
system vacuum, sample flow rate, and source, probe, filter and condenser temperatures. The source
velocity and temperature are monitored during sampling and the sampling rate is adjusted proportionally
if the emission flow rate varies by more than 20% over the sampling period. Otherwise, constant rate
sampling is used.
The dry gas sample and the corresponding condensate are transported to a GC/MS. The dry gas
is analyzed by direct injection. The condensate is analyzed by purge and trap GC/MS, according to the
SW-846 Method 8240.5 The total amount of anaJyte in the sample is determined by summing the
individual amounts from the bag and the condensate
The number of sampling runs to be performed must be determined by the regulatory personnel.
Field and method blanks, field spiked samples, contamination checks and performance audits are
required. At least one field spike sample is taken per 10 field samples. Spiking is performed by either
gaseous or liquid injection into the bag, or by dynamic spiking into the train. Method performance
criteria have been tentatively set according to the SW-8^6 Method 0030 guidelines. Accuracy (percent
recovery) must be greater than 505? and less than 150%. Precision must be less than 50%.
Teflon* must be used for all sample lines and connections. All Tedlar® bags must be flushed
with nitrogen and checked for background contamination prior to usage. The bags must be protected
from sharp objects, direct sunlight and low ambient temperatures (below 0°C) that could cause
condensation of any of the analytes. The bag samples must be analyzed within 72 hours of sample
collection unless it can be shown that significant (>20%) sample degradation does not occur over a
longer period of sample storage. The bags must be stored in rigid, opaque containers during all
sampling, storage ana transport procedures. Bags may only be shipped by ground transportation. The
condensate collected during sampling must be recovered separately'in 40 mL vials for each individual
bag sample collected using headspace-free conditions.
Analytical conditions: Analytical conditions are shown in Table 1. To develop an accurate and
reproducible analytical method, a sample introduction interface1 to the GC/MS was designed. Sample
and internal standard (cs-toiuene) are prepared in separate bags. The bags are then attached to separate
ports and the respective loops are loaded by squeezing the bags. The sample and internal standard are
simultaneously injected by means of pneumatically controlled valves and subsequently combined in the
transfer line. Internal standardization and pneumatic sample introduction are both features that lend
greater accuracy to this method by minimizing the effects of operator error.
Analytical quality assurance procedures consist of ensuring the accuracy of mass spectrometry
mass assignment, toning and calibration, according to the procedures outlined in SW-846 Method 8240.:
Calibration was based on at least three concentration levels using a Tedlar* bag for each level. The
calibration range spanned 50ng to 500ng on column (10 jig/L to 100 jig/L). Quantitation was performed
against the response of an internal standard, dj-toluene, introduced simultaneously with each sample
introduction. An average response factor was obtained from the three levels. A valid calibration curve
showed a relative standard deviation of the individual response factors at each level of 30%. A daily
calibration check was performed by analyzing a mid-level calibration standard. The check was
considered valid if, as above, calculated response factors did not vary by more than 30% from the mean
response factors from the calibration curve. AU samples (including detection limit standards) were
quantitated using the response factors generated from the daily calibration check.
Six anaiytes were selected for the evaluation of the sampling and analytical protocols. These
:ompounds were selected on the basis of existing stability data,1 to test the boiling point range of
Vlethod 0040. The compounds are vinyl chloride, trichiorofluoromethane, methylene chloride, benzene,
oiuene and tetrachloroethene with a boiling point range of -19°C to 121 "C. The compound d,-toluene
vas selected as an internal standard for all six anaiytes.
-------
RESULTS AND DISCUSSION
Several parameters were evaluated. The analytical interface was evaluated for reproducibility of
injection. Two standard procedures for preparing GC/MS standards in Tedlar® bags were evaluated and
the more reproducible procedure of the two was used to generate standards to calibrate the GC/MS. An
instrument detection limit study was subsequently performed. Finally, the sampling train was evaluated
by replicate dynamic spiking. All sample lines and fittings from the stock cylinders to the bag were
constructed with Teflon*. All Tedlar® bag samples and standards were stored at room temperature in
sealed styrofoam containers placed in cardboard boxes. Only new bags were used, and one bag per
batch was checked for background contamination. One method blank was generated for each level
during dynamic spiking. To ensure proper mixing of analyte gases with the diluent nitrogen, Tedlar®
bag standards were allowed to sit overnight prior to analysis.
Reproducibility of Injection: Reproducibility of injection was evaluated by performing repeat
injections through the sample inlet of the fixed loop interface using a standard prepared in a SUMMA®-
polished canister as well as a Tedlar® bag standard. A mean and percent relative standard deviation
(%RSD) of the area counts from extracted ion profiles for each of the six analytes were then calculated.
Similarly, d,-toluene was repeatedly injected using the interna! standard inlet. The %RSDs for six
injections were less than 4% in all cases. The fixed loop interface was shown to be effective in
introducing sample and internal standard reproducibly into the GC/MS system. In addition, there was
comparable reproducibility in sample introduction between bag and canister standards.
Preparation of Tedlar® Bag Standards: Tedlar® bag standards were prepared from a stock
cylinder containing the six anaiytes at a concentration of 500 /tg/L. Nitrogen from an additional cylinder
was used as a diluent Standards were prepared either by allowing the gaseous standards from a stock
cylinder to flow into a bag simultaneously with the nitrogen for a length of time, or in a step-wise
fashion, by introducing the spiking compounds into a bag already partially filled with nitrogen, and then
allowing nitrogen flow again for a specified time. Standards at four concentration levels were prepared
using each method. The levels ranged from approximately 10 fig/L to 100 /ig.'L. The internal standard
was prepared by injecting 5 #iL of a methanol solution of drtoluene through a heated injection port into a
Tedlar® bag containing 1 L of nitrogen.
The standards were analyzed and the results quantitated against the response of d8-toluene. Three
of the four standards were useo to establish instrument calibration and reproducibility. The fourth
standard (in the middle of the calibration range) was then analyzed and the analyte amounts were
quantitated to evaluate accuracy. Results showed a notable difference between the two methods of
preparation. The step-wise method showed greater accuracy (for all compounds except for
tetrachioroethene), higher precision and higher compound response than the simultaneous method.
Instrument Detection Limit: The instrument detection limit study was performed by preparing a
standard at 2.2 pg/L and injecting it nine times. The quantitated amounts in each of the nine replicate
analyses were then subjected to a student's T test and evaluated according to the criteria outlined in
40C.FR Part 136B4 for the determination of the method detection limit. The instrument detection limits
are as follows:
viny: chloride 0.5 fig/L benzene 1.2 pg/L
trichlorofluoromethane 0.5 /xg'L toluene 2.0 fig/L
methylene chloride 0 7 fig'L tetrachioroethene 4.7 ng/L
Dynamic Spiking: Dynamic spiking was performed into a sampling train assembled as shown in
Figure 1. Boiling water was used to generate an atmosphere with 100% moisture in a fume hood.
Experiments were performed in quintuplicate at two concentration levels: 20 ftg/L and 80 fig/L.
Sampling time was 20 minutes at a rate of 1 L/min.
The results (Tables 2 and 3) show excellent precision and a positive bias (mean % difference) at
both levels. The bias appears higher for all compounds at the 20 fig/L level. There also appears tc be
an increase in bias with boiling point at the 80 figFL level. Tetrachioroethene in both cases appears to
show the greatest inaccuracy. The bias may have been caused by volume discrepancies between
measured and actual volumes during dynamic spiking experiments. Experiments performed to evaluate
350
-------
this discrepancy showed a 10%-30% difference. However, lack of sufficient data prevents a better
definition of this difference. The problem may have been caused by inefficient operation of the check
valve at the bag inlet in tbe sampling train assembly, and may therefore be mitigated by its removal.
REFERENCES
1. Howe, G.B., B.A. Pate, and R.K.M. Jayanty, "Stability of Volatile Principal Organic
Hazardous Constituents (POHCs) in Tedlar® Bags," Research Triangle Institute Report to
the EPA, Contract No. 68-02-4550, 1991.
2. Test Methods for Evaluating Solid Waste, 3rd ed., SW-846, Method 8240. U.S.
Environmental Protection Agency. Office of Solid Waste and Emergency Response.
U.S. Government Printing Office: Washington, D.C., 1987.
3. U.S. Environmental Protection Agency, Work Assignment 57, Contract 068-D1-
0010, Project Officer: Robert G. Fuerst.
4. U.S. Environmental Protection Agency, 40 CFR Part 136, Appendix B, "Definition and
Procedure for the Determination of the Method Detection Limit".
The information in this document was funded wholly by the United States Environmental
Protection Agency under Contract No. 68-D1-0010 to Radian Corporation. It was subjected to Agency
review and approved for publication. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
Table 1. Analytical Conditions
Instrument
Sample Introduction Interface3 (SI)
Variac 3400 Gas Chromatograph (GC)
Finnigan 4500 Mass Spectrometer (MS)
SI Conditions
Carrier Gas: Helium
Sample Loop Size: 5 mL
GC Conditions
DB-624 capillary column, 30 m, 0.53 mm I.D., 3 y. film
Temperature Program: -60°C to 200°C @ 20°C/min
Carrier Gas: Helium
Interface Oven Temperature: 200CC
MS Conditions
Mode: Electron Ionization, Full Scan
Electron Energy: 70 eV
Mass Range: 35-260 amu
Scan Rax: 1 scan/sec
-------
Table 2. Accuracy and Precision of Dynamically Spiked Samples — Level 1
Accuracy
Percent Difference Between Theoretical and Quantitated Values
Precision
Sample Label Analyte
Run 1
Run 2
Run 3
Run 4
Run 5
Mean
%RSD
Vinyl chloride
3.33
6.40
4.27
8.63
R. 12
6.15
4.59
T richlorofluoromethane
8.86
7.40
8.29
11.63
13.41
9.92
3.70
Methylene chloride
7.82
5.93
10.62
9.90
16.24
10.10
5.03
Benzene
9.81
12.89
13.88
16.77
23.91
15.45
5.59
Toluene
16.71
22.08
21.62
23.36
33.47
23.45
6.07
Tetrachloroelhene
19.23
27.22
26.28
32.74
43.41
29.77
7.26
Table 3.
Accuracy and Precision of Dynamically Spiked Samples — I^evel II
Accuracy
Percent Difference Between Theoretical and Quantitated Values
Precision
Sample Label Analyte
Run 6
Run 7
Rurt'8
Run 9
Run 10
Mean
%RSD
Vinyl chloride
35.41
59.02
37.13
36.86
29.41
39.57
8.15
T richlorofluoromethane
35.10
52.73
32.76
30.73
26.15
35.29
7.90
Methylene chloride
28.23
37.64
28.36
25.70
24.39
28.86
4.59
Benzene
31.75
54.17
39.86
40.00
35.99
40.35
5.61
Toluene
31.43
56.52
40.25
37.43
38.37
40.80
6.47
T etrachloroethene
50.14
94.28
71.60
71.56
70.08
71.53
8.46
-------
Probe Isolation Valve
Quick Connector
Duct
Charcoal Trap
Filler Holder
(with Filter)
Probe
Temperature Sensor
Purge Line
To
VOST Control
Console
Quick
Condenser
Connectors
Pilot Tube
Glass Condensate Trap
Return
Line
~ Y
CCt£=rr
Bag Isolation
Valve
Manometer
Ice Bath
Taflon
Bulkhead
Condenser Temp(J
3) Filler Temp
Quick
Union
Connectors
5) Probe Temp
X) Stack Temp
O ,_LT
Teflon Union
Air Tight Container
Tedlar*Bag
0
I
Infection Port
lor Spiking
Figure 1. Schematic of I lie Method 0040 Sampling Train
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Field Evaluation of a Modified VOST Sampling Method
Merrill D. Jackson, Larry 1>, Johnson. Robert Ci, Fuerst
Atmospheric Research and Exposure Assessment Laboratory
II. S.Hnvironmental Protection Agency
Research Triangle Park, North Carolina 27711
James F. MeGaughey, Joan T. Burse), Raymond G. Merrill
Radian Corporation
P. O. liox 13000
Research Triangle Park, North Carolina 27709
ABSTRACT
The VOST (SW-846 Method 0030) specifies the use of Tenax® and a particular petroleum-
based charcoal (SKC Lot 104, or its equivalent), that is no longer commercially available. In field
evaluation studies of VOST methodology, a replacement petroleum-based charcoal has been used-
candidate replacement sorbents for charcoal were studied, and Anasorb® 747, a carbon-based sorbent,
was selected for field testing. The sampling train was modified to use only Anasorb® in the back
tube and Tenax® in the two front tubes to avoid analytical difficulties associated with the analysis of
the sequential bed back tube used in the standard VOST train.
The standard (SW-846 Method 0030) and the modified VOST methods were evaluated at a
chemical manufacturing facility using a quadruple probe system with quadruple trains. In this field
test, known concentrations of the halogcnated volatile organic compounds, that are listed in the Clean
Air Act Amendments of 1990, Title III, were introduced into the VOST train and the modified
VOST train, using the same certified gas cylinder as a source of test compounds. Statistical tests of
the comparability of methods were performed on a compound-by-compound basis. For most
eompounds. the VOST and modified VOST methods were found to be statistically equivalent.
INTRODUCTION
The Volatile Organic Sampling Train (VOST, Method 0030:) has been used for nearly ten years to
colled volatile organic compounds from stationary sources.7 The Method 0030 sampling train
incorporates two tubes of sorbent: Tenax-CIGJO (a phcnylenc oxide polymer), with a second tube
containing sequential beds of Tenax-(iC
-------
anal>tes tested other than methyl chloride, ethyl chloride, vinyl chloride, and methyl bromide,
recovery from carbon-based sorbents tended to be low, even at desorption temperature? of ?50°C.
Since Tenax® retains these compounds poorly, a carbon-based sorbent is required to trap these gases.
The modified VOST train is shown in Figure I: the two Tenax® lubes are placed after the first
condenser, with the Anasorb® tube after the second condenser. Analytical procedures of
Method 5041' were also modified to deal with the additional tube without increasing the total number
of analyses. In the field evaluation study, the three tubes were analyzed individually in order to
examine the distribution of analvtes, but in routine application, the two Tenax®1 tubes may be
combined for desorption and analysis, with a separate analysis performed for the Anasorb® tube. A
calibration curve with analytcs and internal standards purged from water was demonstrated to be
superior to other methods tested for initial calibrations and daily calibration check samples; surrogate
compounds were spiked on the sorbent tubes, as in the standard procedure1.
The dynamic spiking system previously described*1 allowed the modified VOST methodology
to be evaluated by using a certified cylinder of gaseous standards during dynamic spiking in the field.
The modified VOST procedure was evaluated using VO.ST (Method 0030) as a referer.ee method.
According to the guidelines of EPA Method 301s. field validation may be performed by side-by-side
comparison of a candidate method to a validated method to establish statistically comparable
performance for the same analytes in the same matrix (i.e.. same source category). 1'he test site
selected for the field evaluation was a coal-fircd boiler that burned chemical waste at a chemical
manufacturing facility.
Bias, any systematic positive or negative difference between the measured value and the true
value of a sample, may result from analytical interferences, errors in calibration, or inefficiencies in
the collection or recovery of an analytc. When the bias of the method is determined for a given
analyte, a correction for the bias may he made. The FPA Method 301 allows for this bias correction
within a range of 90 percent to 110 percent when a candidate method is being compared to a
reference method. Bias correction factors outside this range may be grounds for rejecting the
candidate method.
Precision is the variability in the data from the entire measurement system (both sampling and
analysis) as determined from multiple or collocated sampling trains, following the I ,PA Method 301
procedures, multiple samples using at least two paired sampling trains determine the precision of the
entire system. Use of quadruple (Quad) trains with four collocated sampling probes and four similar
sampling trains allows simultaneous operation of two spiked trains and two unspiked trains. A total
of twenty runs (10 for each method) using quadruple collocated sampling trains were collected using
both VOST and modified VOST to provide adequate samples for statistical (bias and precision)
comparison of the two methods and to allow backup samples in the event that any sample became
invalid due to breakage or loss of data during analysis.
In the field, spiking gas was allowed to flow through the dynamic spiking apparatus for two
hours each day before directing the flow to the sampling trains to minimize any adsorptive losses
during actual Quad sampling runs. Prior to the field test, the spiking gas flow rate delivered to each
of two trains was set to a nominal 3.0 ml./min (250 ng over a 20-minute sampling period). T he
actual amount delivered was calculated from the measured spiking gas flow rate, the measured period
of lime during which spiking occurred, and the measured concentration of the individual components
in The cylinder gas mixture, following collection all modified VOST sampling tubes were
transported and stored at 4°C and were analyzed within 30 days after collection. Analytical results
for the first complete six paired sampling runs (as per Method 301) of both VOST and modified
VOST are shown in Table I. I.sing the criteria for acceptable VOS T method performance shown in
the EPA Quality Assurance Handbook for Hazardous Waste Incineration', the compounds shown in
the shaded area of Table II meet the criteria for acceptable performance.
Using the criteria outlined for comparability of method performance in the FPA Method 301
to compare modified VOST to VOST as a reference method, the following compounds arc
comparable: chlorobenzcne, methyl chloride (chloromethane), vinyl chloride, chloroform, methyl
-------
Glasr;
Win;!
Filter
A
Stack
Heated Glass
Lined Probe
~ ""iree Way
Ciass/Teflon
..nv Valve
lKiu
1/3* C D
Teflon i ire
Condense;
Cnarcoa
rap
/ / vi
Ice Bath
Temperature
'ndicators
^ Vacuum
ffc Gauge
/ Anasorb
1 onax
Rotameter Pump
^ q^s ^
I Meter
:enax:
Silica
1/4" Teflon
Condensate
Meter Box
Exhaust
Sampling Module
Figure 1. Modified VOST Sampling Train
-------
Table I
Results of VOST and Modified VOST
Modified VOST
f ; -;-:vosnri^
Compound
Mean Percent
Recovery1
Portent
RSD
Mean Percent
Recover}*1
Percent
USD
Methyl Chloride
(Chloroniethane)
167.5
56.4
255.3
58.1
Ethvlidene Dichloride (1,1-
Diehloroethaiie)
96.2*
12.6
860*
13.2
Chlorobenzene
91.6*
13.0
84.8*
27.9
Vinyl chloride
44.2
24.2
37.3
39.5
Vinylidene Chloride
(1,1 -Dichloroethene)
96.8*
17.2
77.8*
25.1
Chloroform
98.4*
20.4
95.3*
14.3
Propylene Dichloride
(1,2-Diehloropropane)
149.4*
14.0
117.7*
30.0
Vlcthy l Bromide
J (Bromomcthane)
45.7
46.7
52.8*
27.8
F.thyl Chloride
(Chloroethane)
45.3
30.0
31.4
37.6
Methylene chloride
120.7+
10.9
90.8*
11.7
\tethyl Chloroform
(! ,1.1-1 riehlorocthane)
87.1*
12.1
96.8*
19.4
Carbon tetrachloride
89.3*
12.5
85.7*
13.8
Ethylene Bichloride
(1 ,2-DichIoroethanc)
83.2*
25.1
78.6*
77 n
Trichloroethene
148.7*
3.4
124.0*
16.8
cis-I. i-l>ichloropropene
118.4*
21.0
83.5*
16.1
trans-1.3-1 )ich!oropropene
7< 2»
32.6
47.9*
35.0
1,1.2-Trichlorocthane
117.3*
20.5
81.4*
14.4
Tetrachloroethenc
61.8*
8.0
57.5*
12.5
357
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Table I
(Continued)
Modified VOST
VOST
Compound
IVIean Percent
:j;!:R«eovery' .
Percent
RSD
Mean Percent
Recovery1
Percent ¦;
RSI)
Methyl iodide
(Iodomethane)
89.0*
11.9
77.8*
20.4
Ally] Chloride
(3 -Chloropropene)
26.0
21.1
36.4
29.6
Ethylene Dibromide
(1,2-Dibromoethane)
108.5*
23.2
81.6*
31.0 j
Chloroprenc
85.8*
15.3
76.4*
12.3
Vinyl Bromide
38.0
22.5
28.4
30.9
1 Mean of 6 runs (12 sets of dynamically-spiked tubes).
* Recoveries marked with asterisk (*) indicate acceptable performance, using the
criteria of recovery from 50 lo 150 percent, with percent relative standard deviation
of 50 or less.7
bromide (bromomcthane), methyl chloroform (1,1,1-trichloroctharie), carbon tetrachloride, ethylene
dichloride (1,2-dichloroethane), tetrachloroethene, methyl iodide (iodomethane), and ally! chloride
(3-chloropropene). When recoveries are compared for VOST and modified VOST, the modified
VOST usually shows better recovery. When precision is compared between VOST and modified
VOST, the modified VOST shows better precision. The statistical comparison is performed on a
compound-by-compound basis to determine the equivalence of the two sets of results. The statistical
comparison does not determine which method is better, only whether the two methods are
comparable within a specified range. On the basis of a compound-by-compound comparison, the two
methods are comparable for the compounds listed above and, where they differ, the modified VOST
method usually demonstrates better performance in both recovery and precision. For the compounds
which did not meet the Method 301 criteria for acceptable performance of the method, the VOST or
modified VOST could still be used as a screening method to establish the presence or absence of
these compounds.
Methyl chloride (chloromethane) exhibited recoveries far abo%re the acceptable range,
consistent with results in previous studies.4,5 The compound appears to be formed during the time
that the halogenated analytes are on the sorbent tubes. Since this analyte may be formed on the
sorbent tubes, methyl chloride is not an appropriate analyte for the VOST or modified VOST
method Methyl chloride (chloromethane), ethyl chloride (chloroethane), methyl bromide
(bromomethanc), vinyl bromide, and vinyl chloride were observed exclusively or primarily on the
back (Anasorb®) tube, as expected. Compounds with 30 percent or more sorption on the second
Tenax® tube were methylene chloride and methyl iodide (iodomethane). Compounds with a
significant component (>20% but <30%) on the second Tenax® tube included: vinvlidene chloride
(1,1-dichloroethene), methyl chloroform (1,1,1-trichloroethane), carbon tetrachloride, ally] chloride
358
-------
Table II
Mean Recoveries and Precision of Analytes,
Using the Modified VOST Method
Compound
Mean Recovery,
.%' :;iV
% RSI> ,
methyl chloride (chloromethane)
167.5
56.4
propylene chloride (' 1,2-dichioropropane)
149.4
14.0
tiichloioethene
: Wlp
3.4
methylene chloride
120.7
JiLiili .;;; 1(W
Ci8 1.3-dich]01 opropene Inn- :;H: .. v
318.4
-i : - - 21.0
1,1,2-trkhlorocthanc
T: "Eii7';3
20.5
ethylene dibromide (i .2-dibrouioethane)
108.5
ii;#l
chloroform -.f
¦; ;i:;-" r i:ii9p::||"
j;r-20:4;-;;
vinylidene chloride (1,1 -diehlaroethene)
96.8
ethylidene chloride (1,1-dichlordethaiie)
: 96.2
12.6
chlorotienzene
.:9;1N6;iiiL in;
13.0
carbon tetrachloride
Ihiii;:'!:;:- 89.3
methyl iodide (loilomethane)
1 'S 89.0
11.9 ;;h
methyl chloroform (1.1, l-trichloroetluuie) :
87.1 ¦¦¦:;
ch.loroprene ¦
85.8 ;ii-;; ::.
ethylene dichloridc (i;2:-dichlorocthanc) n
83.2
trans-1,3-dichlorcpropene
75:2v:
32.6
tetrachioroetlieiie .-x:;-hip hi:.
61.8
8.9
brotnomethane
45.7
46.7
ethyl chloride (chloroethune)
45.3
30.0
vinyl chloride
44.2
24.2
vinyl bromide
38.0
22.5
ailvl chloride (3-chloroprcpene)
26.0
21.1
'The shaded area indicates recoveries from 50 to 150 percent with %RSD of 50 or
less.'(3-chloropropene'!, and vinyl bromide. Compounds recovered at acceptable levels
(50-150% for RCRA, 70-130% for NSPS), with acceptable precision (percent relative standard
deviation less than or equal to 50) are valid candidates for VOST or modified VOST.
359
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DISCI AIMFR
This material has been funded wholly or in part by the Environmental Protection Agency
under contract 68-D1-0010 lo Radian Corporation. It has been subjected to the Agency's review, and
it has been approved for publication as an EPA document. Mention of trade names or commercial
products does not constitute endorsement or recommendation for use.
REFERENCES
1. "Test Methods for Evaluating Solid Waste, Physical'Chemicai Methods, SW-846 Manual, 3rd
ed." Document No. 955-001-0000001. Available from Superintendent of Documents, U. S.
Government Printing Office. Washington. D.C. November, 1986
2. G. A. JUNGCLAUS, P. Ci. GORMAN, G. VAUGHN, G. W. SCHEIL, F. J. BERGMAN. L.
D. JOI l\SON. and D. FRIEDMAN, "Development of a Volatile Organic Sampling "i rain,"
presented at Ninth Annual Research Symposium on Land Disposal, Incineration, and
Treatment of Hazardous Waste, Ft- Mitchell, KY, May. 1983. In Proceedings.
EPA-600/9-84-015, PB84-234525, July, I985.
3. L. I). JOHNSON, R. G. FIJHRST, A. I,. FOSTER, and J. T. HLRSI Y. "Replacement of
Charcoal Sorber.t in the VOST," presented at Twelfth Annua! International Incineration
Conference, Kjioxville, TN, May 5, 1993.
4. Laboratory Validation of VOST and Semi VOST for Halogenated Hydrocarbons from the
Clean Air Act Amendments List. Volumes 1 and 2. EPA 600/R-93/123a and b. NTIS
PB93-227163 and PB93-227171. July, 1993.
5. Field Test of a Generic Method fo: Halogenated Hydrocarbons, EPA 600/R-93/101. NTIS
PB93-212181. June. 1993.
6. El'A Method 301. Protocol for the Field Validation of Emission Concentrations from
Stationary Sources. U. S. Environmental Protection Agencv. EPA 450/4-90-0015. April.
1991.
7. Handbook Quality Assurance,''Quality Control (QA/QC) Procedures for Hazardous Waste
Incineration. F.PA/625/6-89/023. January, 1990.
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Comparison of Sampling and Analytical Methods for the Collection
and Determination of Methylene Dlphenvl Diisoeyanate (MDI) from
Oriented Strand Hoard (OSB) Sources
Murk D. Baker, William J. Karoly. and Michael F. Adams
ICI Polyurethanes Group
286 Mantua Grove Rd.
West Ueptford, NJ 08066
The ICI I'olyurcthancs (iroup conducted a multi-variant study of
sampling and analytical methods for the collection and determination of Ml)! from 3
different OSB sources. The study evaluated 3 different sampling trains and derivatizing
reagents al 2 probe temperatures as follows:
1. A 4-Nitro-N-propylbcnzylamine (Nitro reagent) filter alone at ambient probe
temperature,
2. A l-(2-Methoxypheriyl) piperazine (12MP) filler followed by two impingcrs
containing the same reagent in Toluene at ambient probe temperature,
3. A dual 12MP impinger train followed by a 12MP treated filter also at ambient
probe temperatures,
4. A dual 12MI' impinger train followed by a 12MP treated filter also at a probe
temperature of 250 UF,
5. A dual l-(2-pyridyl)pipera/.ine (12PP) impinger train also at a probe
temperature of 250 °K
The analytical portion of the study compared results using Normal and
Reversed Phase HPLC determination of the Niiro jcagent .samples and Reveised Phase
HPLC determination of the 12VIP and 12PP samples. Additional LC-MS studies were
conducted to confirm and identify the cause of a positive bias in the Normal Phase
Nitro reagent analytical results.
The analytical and sampling results will be presented.
-------
Pen-Based Computer System for Performing Source Test Calculations
Frank R. Clay
Emission Measurement Branch
Technical Support Division, OAQPS
U.S. EPA
Research Triangle Park, NC 27711
The Emission Measurement Brunch has developed open-based computer system
lor Methods 1 through 5 (40 CH< 60, appendix A) which is designed to perform
on-site emission source test calculations and for data reduction after the test effort has
concluded. The system uses EXCEL for Windows and is suitable for use by anyone
who performs emission tests, observes emission tests, or who needs to reduce or verify
emission testing data. The system is designed for people who have minimal computer
skills, and data can be handwritten upon a computer screen using an electronic
stylus or "pen"; keyboard and "spin button' data entry options are also available.
When sufficient data have been entered, the system performs the calculations and
displays the results. Future plans are to adapt the pen-based system to as many
Environmental Protection Agency methods as applicable; and the programs will be
available on the Emission Measurement Technical Information Center Computer
Bulletin Boaid as well as upon request.
362
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Odor Incident Sampler For Fenceline Evaluation Of Air Toxics
William F Boehler, Joette Campo-Pavelka, Kenneth M. Hill and Paul R Ames
Suffolk County Department of Heal'.h Services
Center for Forensic Sciences. Hauppauge, NY.
ABSTRACT
Governmental air toxic regulator agencies receive numerous daily complaints f'om the public regarding
air pol.ution related odor inciderts. Historically, due to the sporadic frequency of occurrence of such incidents, it
has been difficult If not impossible for a regulatory group to captu-e the "Odor Incident/Maximum Concentration"
type sariple, w'thcut the use of expensive continuous air monitoring devices. In an effort to overcome this Suffolk
County designed an "Odor Incident Sampler'' which can be activated simply by the general publ c. The device
performs all air sampling functions when a complainant plugs the unit into an electrical line. Upon activation of the
Odor Sample' the individual records the start time, and then notifies the appropriate regulatory agency that an
odor incident is occurring. Within an appropriate time period air quality agency personnel collect the samp'efs)
and recharge the sampler for subsequent run-offs.
Varicus types of a r sampling equipmert can be placed inside the locked tamper proof shelter (for
example, Sorbent Tubes, Summa Cannisters, Impingers, etc.).
Pro;ect examoles are presented, including details of sample collection, and laboratory analysis.
INTRODUCTION
Under the 1990 Clean Air Ac; Amendments (CAAA) and subsequent additions governmental agencies are
required to monitor and reg'j'ate 189 Hazardous Air PclLitants'. The CAAA requires special controls called
National Emissions Standards for Haza'dous Air Polbtants (NESHAPS) for pc'lutants that cause serious or
irreversible health e'"fects.
To aid in the implementat'on of the CAAA, the U.S. Environmental Protection Agency (EPA) encourages
state 3nd local agencies to develop their own air toxics programs to monitor and control high-risk "point' sources,
and address mu'ti-pollutart, multi-source urban toxics problems*. In addition NYS has published short term (1
hour) Gjideline Concentrations (SGCs) and Annua' Guic'cl'ne Concentrations (AGC's) for which no state or
federal ambient air quality standards exist".
To he'p address the above concerns Suffolk County has developed the "Oder Incident Sampler."
EXPERIMENTAL
The Odor Incident Sampler (OIS) diagrammed in Figure 1. was originally designed in late 1989,
constructed and tested in the early spring of 1930 and initially field deployed in May 1990. The OIS was designed
with the following features:
(1) SarnplaJWedia Integrtv - A General Valve Corporation, Fairfield New Jersey model 9-89-900
stainless steel valve (with mcdel 90-29-100 valve driver) was placed in line with sample media
between inlet probe and media contact point. The two-way solenoid valve which is normally
closed prevents air from diffusing into the sample media. Since back diffusion through the other
-------
end of the sampling train (the vacuum pump end) does not occur, one solenoid valve is adequate
in preventing air diffusion for at least two (2) months.
(2) Ease of Activgtio.o - By plugging the ur.'t into an electrical outlet, the OIS automatically performs all
necessary air samp'.ing lunctions.
(3) Inlet Probe Integrity - Only stainless steel tubing and fittings are used.
(4) Documentation of Critical Parameters - An inline timer allows the selection of the targeted sample
duration period (normally ore (1) hour). An elapsed timer keeps track of the actual time sampled.
Flow rates are checked before and after sampling.
(5) Citizen/Complainant Documentation - The complainant who activates the OIS is asked to fill out an
Odor Incident Report Form which documents the date and time of activation, temperature,
estimated wind speed and direction, and odor intensity rating. Upon activation the complainant
telephones an air quality official to report OIS start up, and to arrange sample pick up and
recharging of the media. Once activation time is established, resident reported meteorological
measurements are compared to official meteorological station readings, in order to best determine
the origin of the source of pollution.
(G) Mu'tiola Sample Col'ection - Although the design as shown is for the collection of a single sample,
changeover to a multiple sample collection may be easily accomplished by using a branched inlet
into the existing manifold port (see Figure 1.)
(7) Shelter - Protection of sampling equipment from rain and snow
(8) Security - Unit is constructed with a locking mechanism for protection against vandalism In
addition it is recommended that the unit be placed in a secure area.
(9) Stabilizing Platform - The placing of cinder blocks on the stabilizing supports proves to be
adecuate in preventing the unit from toppling over during high wind conditions.
(10) Utilities - adequate outlets are needed for incorporating additional samplers. Fluorescent I ghting
to provide visibility for the Interior of the OIS Is required to allow possible recharge during evening
hours.
Desirable additional features for a commercially manufactured'1' OiS unit should include any or all cf the
following:
(1) Modern Activation - This feature enables a network of samplers to be activated simultaneously.
(2) MTcronrocessn-/Dat3!oaqsr Based System - With battery back-up and real time clock to
electronically document critical air sampling parameters.
(3) firgi:nd_Eault Interruption
(4) Shs'ter Heatiny and Cooling - This enables an agency to utilize temperature sensitive media (;e ,
Impinge- liquids freezing) to be sampled throughout the year.
(5) Wind Sensor - Although desirable this feature is not necessary if meteorological information is
available locally.
LABORATORY ANALYSIS
Samples are analyzed according to sample type. For example, the majority of samples collected to date,
involves the ana'ysis of toxic VOC's as listed in the Clean Air Act, utilizing an automated non cryogenic multi-layer
-------
Sorbenl tube. GC/MS technology^. (see Table ".)
Additional rr.ethcdologies used tor the project examples sited below, sre NIOSH Method 3500 for
formaldehyde using an imc'nger collect on. ard EPA Method 8270B utilizing a Hi-Vc'ume f Iter collection.
RESULTS and DISCUSSION
After four (4) years of air sample collection, the origins' OIS and subsequent newer versions, cont'nue to
function as des gned, w'th no major mechanical or pneumatic problems encountered
I he public has beer very appreciative of the employment of the OIS People prefer to have their odor
episode occurrences addressed with actual monitcing, thereby proving or disproving the existence of a hc-a".h
concern
Two OIS project examples are listed below. Both projects were :nitiated because people in a res>dentia'
area corrolainec about odorous cmiss'ons from a nearby industrial source
(1) Circuit Board Manufacturer - Fornaldehyde concentrations on a homeowners property
exceeded both the state and federal (1 hour) standards, (see Table 2.) Methylene Chloride was
also found to be above background levels, however no existing standard was exceeded, (see
Table 4.)
(2) Plast'cs RemaTufacturino Cojjjpration - Bis(2-E:hyl Hexyi) Phthalate was detected in
pa-ticulate matter at concentrations which far exceeded arrbient levels, (see Table 3.) Additional
air contaminants which exceeded background levels induced 1,1-Dichloroethylene and
1,1,'-Trichloroethsne. (See Table 4.)
CONCLUSION
Tne use of the OIS demonstrates the ability to collect Odor Incident/Maximum Concentration air samples
which can be used for corrpl ance purposes. Although Continuous A'r Monitorirg (CAM) is often necessary use
of the OIS can be a ccst effective alternative, which reduces the volume of CAM required
Fence.me air monitoring of fugitive emissions from point sources to evaluate acute population exposure, is
a proven application for the Odor Incidert Sa.mpier.
ACKNOW1 FDfiVIFNTS
We gratefully acknowledge Suffolk County Health Commissioner, Mar/ E. Hibberd. M.D., M.P.I I.. Chief
Medical Fxaminer Slgmund M. Merchel, M.D.. and Robert Capp, Sideris Caramir.tzos, Mary Carpe.ntlere and
Artnur Lussos frcm the NYS Department o* Fnvironrrental Conservator for their project support and ieadershio.
The authors especial'y appreciate the co-ope'ation and centric jtions of Ida Puntur'eri, Jo Ann Laace* and
Barry Pass n in the p'oduction of the manuscript and visual aids.
RFFFRFMCFS AND FOOTNOTES:
(1) W. A. MoClanr.y G.f. Lvars K.D. Oliver el al.. "5:a!ts ol VOC Methods Deve opment to Meet Monitoring Requirements -'or the Clean
Air A;t Amendments o' 1S9X in Proceed rg cf -he 1991 E=>A/A£WMA nle-nal onal Syirposium or Measurement of Tex c.and Related Air
Pq utar's. VIP-21, A r & Waste Management Associat oi, Pittsburg. PA, 1991. pp 367-372
(2) U.S. Environments Protection Acency, Meeting t^e environmental Cha engg E~A Put! cation 21K-20D1.1990.
{3] New Ycr« State Department of Environmental Conservation Nqw York fits'? Air Guide - 1. NYS, D.F C., Div of Air ResoL'ce3, 1991
Ec tion.
(4) The "*i owing companies have the ability ard lh: r»fx:cif cotiorE to bji d sucl" units (1) Xon Tech Inc. V;m Nuyi CA. (?) Scientific
Instrurrental on Spec a is:-; (SIS) Moscow, Icahc. '3) Envirccisn' nc., Kemnlesv Ite. PA.
365
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(5) W.F Boeder, R L. Httin, and K M.Hil "Fvc'uation of n Non Cryoger.'c Automated Multitube Thermal Desorption Systerr for the
Analysis cf A r Toxics" in Pfoceec na cf the I960 EPA/A&WMA Irterrational Svnnosium fir Mcnsurmren? of Toxic and Related Air
Pel i:ants. VIH 17, ar & Waste Management Association, Pittsburg PA, 19S0 pp 699-708
TABLE I. CLEAN AIR ACT AMENDMENT-VOC's
(28 nL Standard)
T.me C j;:
e.65 Fteon 12
c.ci Frnon 114
t. 'jO chloroisthar.s
9.73 Viiiy. Chlcriiu
10.14 1,3-Butadi«1.2
!.")?« l-:-.hy" pr.c Cwrtr
10.1->8 tfet'nar.ol
13.32 Brosotr.&tl'ianc
11.27 Chlorocthu:i«
15.5H tJromorth-r.i?
1 r. .-9 i?r»or. 11
15.59 2-Prop«r.al
23.14 Propylene Oxide
?:i fr Kr^on l 1 i
20. .->4 1. lOichlcrcetnyler.s
21.91 Aceuiu.ittile
22 . 24 lodcuethane
?.'¦ . \ 1 c rc - "i - P rcp*r.®
24 10 Methy.«ne Chljnca
25.35
25.55 Methyl tert-Bu-.vl Ethsr
2 ; f,o :i*vanc
25 .6-7 i. lo.shlcrsethano
29.26 Vinyl Acetate
Tltr-j Cu:-.'v,rni7id
3 3.67 1, 2-Spo.v.ybutane
11.21 Methyl rrhyl Ksmr?
12. €5 Chloroform
34.40 1.1,1-Trishluiuethane
35.21 2,2,1 ¦¦¦Trimer.hylperc.ane
35 ,4\ C'arh^n TorrarV.oride
3j.77 1, 2 Oicbloroethane
3 5.95 Benzene
37.59 Trichloroethyler.e
33.1.'} Krhvl Anrylat*
33 42 l, 2-Dichloropropane
3 5.12 Mfcthyl Methacrylatu
3 9.55 1,4 Oioxane
3 5 2 Ni Tronropem*
40.19 Methy. isofcuty- Ke-or»e
40 22 Epichlorohyjtin
4C .€5 c.s-l,3-tichluicpropene
41. €0 Tcluenc-
41.53 trans-1,3 Cich'orcpropone
42.32 1,1, £ Tr:.£hlnrnrhane
Titrn CQr*pnK^.d
45 .35 Ethylbertznncs
4S . V» m Y.y'fir
46. a J o-Xviene
4*. 58 Stytene
47 . 28 Broa.ufoim
47.32 leupropyl Benzene
47.55 1,1,1,2 Tnt.ra~hloroct.hcnc
4 V . £ . Tr.r . Std . uinrr>b<*n7:»»n^
4 V or. ], / , j-Tri chicrrprcpt-ne
43 . L-0 3.3. 3-TriT.ethyl'oenzer.e
4 5.32 1,2, 4-Triinetl'.yltHjiizent!
4S.47 Difhlorcethyiether
SO . 13 mOichloiobensenc
5C.32 p Dicrhl srohrn-.rr#
?>C .f.! a chl^rnfcuuen*
'.•C 57 p-Dvethylber.zene
51.06 o-D.chlyruL«:)zei»H
53 . CO 1,3, 5-Tt ichlctcber.zene
53 CI Nir.robenznnn
54 . 1 9 1, 'J., 4 Tri Hr>:*»rhl 'r>*-oh,irnrii c*~e
S4.77 Naphthalene
Table 2. Circuit Board Manufacturer -- Impinger - OIS Collection
CIS I'ormaldehvdc Results
Residence
Date (1993) Cone, ppb(v) |
RM
MO
717 '
RM
7/8
>1513
RM
7/14
562 :
RM
7
213
ML
S.'6
.22 ;
RM
8/10
29
ML
8,10
<25
RM
8/10
409
ML
8,11
< 29
Formaldehyde Odor Incident Levels
Circuit Boa-d Manufacture' Feneeline
366
-------
Table 3. Plastics Remanufacturing Particulate OIS Collection
OIS - Bis (2-Ethvl Hexvl)
Phthalate Results*
Date (1993)
Cone, ug/nr
7/16
0.067
7/21
0.105
7/23
0.092
8/4
0.193
9/30
0.108
10/18
0.580
11/1
0.279
12/7
0.305
Ccurty i-»"t culatt Core
Cffiis (2-gthyi
P'r&iljtt- ' ¦j/.ll'
Bls(2-EthyIHexyl) Phthalate Levels
Plastic Rerram,faduret Fcncofintf
O.S
0 5
0 4
¦S 0 3
o>
=>
0.2 j
0.1 :
0
|t 12/07
II
Table 4.
VOC Project Results
Sorbent Tube - OIS Collection
Industrial Source
OIS-VOC" Maximum Results / Comparisons
of t'nissions
• U.-Dichlcrc;c!hylcnr
Methylene Chloride
l,l,l'TricJiIero::hane | Benzene
i ,2A-rinicthyibesi/ctiC
Plasties Remfg.
>15.1
0.7
>20.6 3.5
0.8
Circuit Bd.Mfg
2.1
8.3
1.8 | 4.6
1.0
Odor Incident Monitoring
Maximum VOC Concentrations
' Plastic Rmf<
^Circuit Board
367
-------
Figure 1.
Odor Incident Sampler
Air
In
niiijcs
Sucport, (For Cmdcr
Biocx ^ PlaOTrrant)
/"" " £ 7=
100' Outdoor
Ext. Cord,
4j3TCjVcdjIe Suppoi
(W/ Wing iiits J
368
-------
SESSION 7:
GLOBAL CLIMATE CHANGE,
MOUNT MITCHELL
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Intentionally Blank Page
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Monitoring of Regional Chemical Climate Change
at Mount Mitchell, North Carolina
V.K. Saxena
Department of Marine, Earth and Atmospheric Sciences
North Carolina Slate University
Kaleigh, NC 27695-8208
One of the objectives of the National Global Change 1'rogram is to seek
plausible answers to the following question: What is the radiative forcing from
greenhouse gases, aerosols, and clouds on the Earth's climate system, and what are the
feedbacks and processes that regulate the net radiative balance of the eaith's
atmosphere? A critical survey of the existing evidence reveals that the trends in the
average global temperature of the F.arth-Troposphcrc system and in global precipitation
patterns are mitigated by several natural and anthropogenic differences between the
northern versus southern hemisphere. In contrast, climatic changes on a regional scale
have been more convincing during the last two decades. A case in point is the
frequency of droughts experienced in the Southeast. The objectives of our study are
addressed to understand the cloud-climate feedback mechanisms on a regional scale,
with particular emphasis on the climate of the Southeastern U.S. We aim to study the
impact of the natural and anthropogenic aerosols on the regional cloud albedo. This is
done by observing the microphysico-chemical characteristics of clouds that form at
Mt. Mitchell, NC (highest peak, 6,684 ft or 2.017 m MSI. in the eastern U.S.; Mt.
Mitchell State Park is a designated United Nations Biosphere Reserve). The cloud
reflectivity is simultaneously monitored by the satellite-based Advanced Very High
Resolution Radiometer (AVHRR). Clouds with contrasting microphysical and radiative
characteristics arc formed at the site when air masses of marine, continental, or highly
polluted origins arrive. Analysis of the First Year Data Base suggests that
our project offers some very promising insights into the cloud-climate feedback
mechanisms. Clouds formed by polluted air masses had pH as low as 2.4 and by
marine air masses as high as 4.75. The latter were found least reflective.
371
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Air Mass History versus Cloud Water Acidity: Observations and Model Results
from a Remote Rural Site
James C. llman, V. K. Saxena, K. Lee Burns, and John D. Grovenstcin
North Carolina State University, Department of Marine, Harth, and Atmosphere Sciences
Raleigh, North Carolina 27095-8208, U.S.A.
ABSTRACT
Cloud water acidity, as measured at a remote rural observing site, is related to the pathway, or
trajectory, taken by air parcels passing over areas with varying levels of pollutant emissions. Areas of the
country that are high emitters of pollutants, such as SON and NOx, affect the cloud water acidity of the
ensuing clouds. Field studies at Mount Mitchell State Park (2,038 meters MSL) during June and August
of 1993 have resulted in observations of cloud water acidity for 37 cloud evems of varying durations.
The measurements were taken with a passive cloud water collector mounted atop a 16 5 meter
meteorological tower Calculations of the backward trajectories for these cloud events are accomplished
by utilizing a hybrid Eulerian-Lagrangian computer model called Hybrid Single-Particle Lagrangian
Integrated Trajectories, or HY-SPI.1T. In this study, comparisons of selected cloud events from the 1993
field season with similar cloud events observed during the 1986-1988 field seasons are investigated Of
the six cases investigated here, four events contained cloud water acidity averages which fell within the
range of historical data from 1986-1988. for the air masses determined from model back trajectories.
Two other cases, both marine in origin, had average acidities slightly below those based on historical
ranges.
INTRODUCTION
Interest in the potential effects thaT increases in the levels of airborne pollutants could have on the
atmosphere has steadily accelerated in recent times. It has been postulated (Ghan, et al., 1990)' that
greenhouse warming of the earth's troposphere due to a doubling of C02 could be counteracted by a
small 2% increase in the shortwave albedo of low level clouds. The determination of albedo of clouds
forming over certain areas can be done by assessing the air mass origin of the clouds via back trajectory-
analysis. In this paper, we will attempt to show a potentially useful method for performing the required
back trajectory analysis For the purposes of this particular study, the scope will be reduced to a
comparison of certain data-sampling instances, from here on referred to as cloud events, with similar
cases from a previous study spanning over the years 1986-1988 There are two reasons for performing
this comparison. The first is to elucidate a method for monitoring long-term changes in cloud chemistry
characteristics. The second reason is to evaluate the effectiveness of the modeling teglinique used to
generate the air mass histories in this study.
Categorization of air masses traversing the Mount Mitchell observation site can be done by
utilizing emissions data provided by the Environmental Protection Agency (EPA 1993)2. The Regional
Emission Inventories for the 4S contiguous United States allow categorization by state of various forms
of anthropogenic pollutants such as SOx and NOx. By using these emissions data, the statewide
graphical representations of the country's heaviest pollution sources can be formulated, as shown in
Figures la and lb For both cases, it car. be seen where the largest pollutant emitters are located, relative
to Mount Mitchell. Thus, a categorization of air masses by geometric proximity to Mount Mitchell has
been devised (I .in and Saxena, 1991)"'. The air masses are called "polluted" if they are transported from a
region bounded by 290° to 65° (Sector 1) azimuth relative to Mount Mitchell, "marine" (i.e., "clean") if
transported from a region bounded by 210° to 65' (Sector 2), and "continental" if transported from a
region bounded by 210° to 290^ (Sector 3). Obviously, considerable cross-over between the three
372
-------
sectors is possible and expected. However, some air masses which move primarily within one sector are
expected to exhibit cloud acidity characteristics which reflect the level of pollution wiThin that sector.
Experimental Methods
Goud water samples were taken at Mount Mitchell during two month-long campaigns in June and
August of 1993. The main observational platform was a 15.5 meter walk-up tower instrumented at the
top with an R.V1. Young wind speed and direction windbird, a temperature/humidity probe, and a
barometric pressure transducer. A detailed review of the experimental procedures employed during the
field season for the receipt and analysis of cloud water will be riven elsewhere in these proceedings
(Saxena. 1994)4
Results and Discussion
Of ail the events monitored during the 1993 field season, six events were chosen for tliis study to
be investigated further These six events were chosen based on the following criteria (see Tabic 1):
1) The desire for a variation of the air mass sectors (i.e., a representative sampling of sectors)
2) Wide range of cloud acidity av erages (average pH's) of the study volume.
3) The desire for cloud events essentially tree of liquid precipitation (See Table 1 footnotes tor
events where some liquid precipitation was encountered).
4) The desire for a representative mixture of events of varying length (i.e., long: greater than or
equal to 8 hours, and short' less than 8 hours).
5) The desire for a roughly equivalent number of events from each of the 1993 field season
months, June and August, so as to reduce any potential climatological bias.
The computer model which was used to produce the back trajectories for the above cases is
known as Hybrid Single-Particle Lagrangian Integrated Trajectories, or HY-SPLIT (Diaxler, 1992)5.
This model is a Multiple-Layer Lagrangian program which uses pre-formatted meteorological data as the
basis for the trajectory calculations. A number of gridded data formats can be used in this program, but
for the purposes of this study, the Nested Grid Model (NGM), version 06, was employed, primarily
because it is easily archived and routinely maintained at the Air Resources Laboratory in Silver Spring,
Maryland. Air mass trajectories from the 1986-1988 field seasons, which will be the comparison base for
this study, were generated via hand analysis of consecutive 850 millibar charts. Thus, it is a key purpose
of this document to demonstrate a much more advanced method for the production of the trajectories.
Case 1—June 19. 1993: 0500Z-0700Z ¦ The back trajectory generated by HY-SPLIT is given in
Figure 2. The trajectory in Figure 2 is for 0600Z and had a corresponding pH value of 3.22. This cloud
episode is categorized as being short in duration, about 2 hours, and having a fairly low average pH of
3 1910 04. Thus based on our air mass sectors, we would expect this trajectory to have at least passed
through fairly polluted regions of the United States (Sector 1). Interestingly, Figure 2 clearly shows an
anticyclonic 48-hour trajectory with its starting point near the South Carolina coast. This should indicate
that since the air mass is of marine sector origin, the cloud water acidity for this event should probably be
somewhat higher than is observed. How much higher is somewhat subjective, but historically for Mount
Mitchell, marine air masses would be expected to result in pH values in excess of 3.44 (on average) (Lin
and Saxena, 1991 )3. That this was not observed is of some interest, because in assessing the cloud water
acidity of the majority of "marine" events for the entire 1993 field season, including those events that
contained samples with rain, this phenomenon was a repeated occurrence. Reasons for the perceived low
values are not obvious, but one possibility is the existence of individually high pollutant emitters in Sector
2, probably fairly close to Mount Mitchell. Comparison with the short marine trajectory as derived for
May 16, 1987 indicates the obvious discrepancy This event trajectory is matched in Table 1 with an
average pll of 3 63 ±0.13, (see Figure 6 for the trajectory) which is much easier to understand given the
air mass origin. Thus, we could suspect that there may perhaps be a flaw or other problem with the
model or model calculation routine This seems unlikely, however, as one very obvious characteristic of
-------
the model trajectories for all the 1993 events (which were run every hour of each event ) is that the results
arc all very consistent with each other. Wildly changing trajectory directions over the course of a very
short period of time during a particular event would certainly indicate a design flaw, or other problem,
but this was almost never the case.
Case 2--June 16. 1993: 1100Z-13007,. This event (Figure 2 shows the representative trajectory,
for which the corresponding pH at 1200Z was 3.45) had an average pH of 3.44 ± 0.01 and was again
short in duration, approximately 2 hours. The nature of this event, as indicated by the trajectory, is
clearly continental (Sector 3) and thus should reflect a moderate pi 1 level, which it seems to do.
Moderate here would most likely consist of pH levels from a low (very roughly) of 3.04 to a high of 3.94
(Lin and Saxena. 1991)'' based upon historical averages from the 1986-1988 field seasons The average
for this event falls well within that range. For the corresponding case during the 1986 field season
(August 4, 1986), which was a long event, the average pH was 3.05 + 0.32, which is right at the lower
boundary for that which might be expected unless the upper end of the standard deviation is considered.
This is probably due to the fact that not all of tliis trajectory was contained entirely witliin the continental
sector (Sector 3). As shown in Figure 5, this trajectory passed near the termination point at Mount
Mitchell through Sector 1 (th^ polluted sector), and thus undoubtedly picked up some of the more
polluted characteristics. Unfortunately, due to the relative lack of events from the 1993 field season
which closely conformed to the requirements enumerated at the beginning of this section (e.g., little or no
cloud with rain, desire for varying event lengths, air mass sectors, etc ) it was necessary to compare this
event with an event from the 1986-1988 dataset which did not necessarily match the pathway exactly
However, if the fact that the August 4, 1986 example did pass at least partially pass through a polluted
sector is accepted as true, then the corresponding reduction in pH is somewhat more acceptable
Case 3—August 8. 1993: 0200Z-0600Z. Figure 3 shows a representative trajectory for the short
(~4 hour) cloud event of August 8, 1993. Again, a continental trajectory is in evidence, with a
corresponding cloud water acidity average of 3.64 ± 0 13, and an individual value at 0400Z of 3.61.
Here, the average acidity fits in very vveil with historical averages for this type of air mass trajectory, as
explained for the previous case. Again, though not all of the trajectory runs for this event are shown, a
noticeable consistency was observed in that all examples am essentially due west through Tennessee and
into either northern Arkansas or southern Missouri. The corresponding case from the 1986 field study
(July 1, 1986) does not actually carry along the same path line as does the August 8th example, bu* in this
case does still pass entirely within one sector (Sector 3) As can be seen from Figure 5, the 1986 example
displays more curvature at the start point in south-central Missouri but more or less covers a similar
region of Sector 3. The resulting cloud water acidity average for the July 1, 1986 trajectory was 3.22 ±
0.17, and tliis also was a short event, as giver, in Table 1 Thus, we can see that both events contain pH
averages which reside within the accepted regime for an event with a suspected continental air mass
history.
Case 4—August 19, 1993: 08007,-! 4007. The fourth example to be briefly investigated in this
study is that of the short (~6 hour) cloud event of August 19, 1993, which, from Tabic I, had an average
pH of 2.96 ± 0.08. This acidity level is fairly low and was one of the lowest average pH events for the
entire 1993 field season (tied for fourth lowest overall and second lowest in August). The trajectory in
this case, as given in Figure 3 (pH 2.86 at 1 lOOZ), passes mainly through northern North Carolina,
southwestern West Virginia, and Ohio, which means that a clearly polluted influence (Sector 1) is
indicated to be dominant in this example. As seen in Figures la and lb, West Virginia and Ohio, are, on
average, very heavy emitters of SO,, and thus reduction of overall cloud water acidity would certainly be
expected. This case was also fairly rare for the 1993 field season in that it was almost exclusively the
only event over which the entire time period of the event resulted in trajectories emanating from the
polluted sector (all other events which indicated polluted influence also contained at least some trajectory
components within the other two sectors). The chosen case of correspondence from the 1987 field
season (August 12, 1987, shown in Figure 6) was very similar in overall track and length and resulted in
374
-------
an average acidity of 3.27 ± 0.29, which though somewhat higher, falls wel! within the prescribed
historical range (from the 1986-1988 field seasons) for the polluted sector of approximately pH 2 94 to
3.82.
Case 5--.lune 24 to 25. 1993: 24/22Q0Z-25/1500Z. The fifth case to be discussed here is an
example of a long event with trajectories largely observed in the marine sector, as in Figure 4. The actual
value of the pH for the trajectory in Figure 4 was 3.47 on June 25th, at 0700Z. From Table 1, it is shown
that the event itself had an average pH of 3.27 r 0.21, which is below the lower end of accepted
"climatological" norms for this region. As mentioned in Case 1, it is unknown as to what may be
suppressing the acidity for trajectories emanating from this region, however, in this case, two possibilities
may exist. First, depending upon the actual path of the trajectory close to Mount Mitchell, there may be
local heavy pollutant emissions which may "artificially" reduce the pH even though the majority of the air
mass traverses relatively "clean" regions The second possibility is that the average may be a statistical
anomaly. Even though the average is quite low for this event, the ranee of pH's observed for this event
spanned from a low of 2.86 to a high reading of 3.51. The 2.86 and other pH's below 3.00 were
observed at the beginning and the end of this event. This is common for many cloud events and is usually
a result of a low liquid water content (LWC) which occurs at the beginning and end of most cloud events
due to the evaporation of cloud droplets in the forming and dissipating stages, respectively (Lin and
Saxena, 1991)"' The only event from the 1986-1988 field studies which at least crosses similar areas as
compared to this trajectory is a trajectory computed for the short event of August 19, 1986 This
trajectory, though not similar in path, crossed a large percentage of North Carolina from the east as did
this example. The 1986 event had average pH of 4.55 ± 0.09 and thus clearly exhibits expected marine
acidity levels. See Figure 5 for the actual path of this trajectory.
Case 6—August 5.1993: 0100Z-1600Z. The last of the cases to be investigated in this paper
involves the long (*15 hour) event on August 5, 1993. The average pH for this case was given La Table 1
as 3.48 ± 0.28. The trajectory for 0900Z given in Figure 4 cleariv shows a zonal (east-west) continental
trajectory with a corresponding observed pH of 3.59. This example almost perfectly gives a
representative pH value for suspected trajectories emerging from the continental sector. In fact, all
trajectories for this event were very similar to the example in Figure 4, and all observed pH values with
the exception of the last three or four in the time period were in the region of 3 50 (again, at the
dissipation stage of the event, pH's dropped likely due to evaporative effects). The example chosen from
1987 (June 29, see Figure 5) turns out to be very similar in the pH average (pH 3.56 ± 0.30, see Table 1)
for the event and it also runs essentially east-west (with a small amount of north-south meander near the
origin) and thus compares with the 1993 example very well for both criteria. The comparison between
these two events therefore appears to be qualitatively the best of the six comparisons presented here and
thus may indicate that, at least for the continental sector, very little overall change in pollutant emissions
for that sector has occurred in the time span between the two study campaigns.
CONCLUSIONS
One of the objectives from the work at Mount Mitchell was to quantify the origin of air masses
traversing the observing site. In this paper, we have experimented with a model which will do this. From
the above case studies, it is clear that all of the cloud events from the 1993 field season can be
investigated in the same manner. All that was attempted in this paper was a demonstration of a
methodology that could be used to perform such a task Additionally, wc sought to determine if the
model is, m fact, an accurate measurement tool for the stated purpose. The majority of the results
presented here indicate that the model is of sufficient accuracy to ensure use on a much wider scale for
the same purpose, although the data also shows that in some cases, there may be small-scale influences
which affect expected results. Thirdly, we can conclude that in order to assess long-term changes in the
acidity of cloud water impacting Mount Mitchell, much more on-site data sampling is needed, over many-
years. Based on the results of this necessarily limited study, is it unclear whether or not increasing or
-------
decreasing levels of" pollutant emissions are hav:r.g a noticeable effect on cloud water acidity Many more
field seasons will be required to quantify the net effect conclusively.
REFERENCES
1. Ghan, S I; Taylor K.E.; Penner, J.E. Model test of CCN-cloud albedo climate forcing.
Geophysical Research Letters 1990 1_7, 607-610.
2. Regional Interim Emission Inventories (1987-1991): Volume II: Emission Summaries, Office of Air
Quality Planning and Standards, FPA-454/R-93-021b; U.S. Environmental Protection Agency:
' Research Triangle Park, 1993, pp 21-70.
3. Lin, N.-H ; Saxena,V.K. In-cloud scavenging and deposition of sulfates and nitrates: case studies
and parameterization. Atmospheric Environment 1991 2SA 2301-2320.
4. Saxena, V.K., "Monitoring the regional chemical climate change at Mount Mitchell, North
Carolina," in Proceedings of the 1994 A&WK-WU.S. EPA International Symposium on Measurement
of Toxic and Related Air Pollutants, Pittsburgh, 1994, pp to be determined.
5. Draxler, R.R., Hybridsingle-pwticle Lagrangian integrated trajectories (HY-SPLIT): Version 3.0—
User's guide and model description. NOAA Tech. Memo ERL ARL-195; .Air Resources Laboratory-
Silver Spring, Maryland, U.S.A., 1992
6. Yeh, J.-Y.R., Measurements of cloud water acidity and windfield for evaluating cloud-canopy
interactions in Mt. Mitchell State Park, MS thesis (available from D.H. Hill Library. North
Carolina State University, Raleigh, NC, 27695), 1988, pp 49-50.
Table 1. Ckuc dvent type, 'ength. average dctid water acidity values, ami dominant ajr mass sectors for selected 1593 6eld
ser_son events ard rorrcrpording events from the firld study,
Event
Event
Hours
Avg.
Dev.
Air Mass
Event
Evt>nt
Hours
Avg-
Dev.
Air Miisn
Length
(Approx.)
Pii
Sector
Length
(Apsrox.)
pH
Sector
6/19/93
Slwrt
2
3.19
0.04
2
5/.6/87
Shor.
3
3.63
0.13
2
Short
2
3.44
0.01
,3
8/4/86
Long
V.
3.05
0.3?,
1 aiui 3
S/&/9G
Short
4
3.64
o.;3
3
7/1/S5
Short
4
3.22
0.17
3
S/19/S3
Short
6
2.96
0.08
1
S/12/87
Short
G
3.27
0.29
1
6/24-S5/33"
Long
17
3.27
031
o
8/1S/86
Short
4
4.55
009
2
8&93"
LonS
15
3.48
0.23
3
6/29/36
L°r£
10
3.56
0.30
3
Soles-. * - Clone and Ruin @ V24/2300Z; ** - Cloud ar.d Rain & MS/0100-0200/
Units:
Figure 1b. Emission of Nitric Oxides
for the Eastern US *s ct 1991
:igure *a. Emission of Sclfur Oxides
fcr the Eastern US as ol iy91
376
-------
Pijurc 2. Model 'jack trajectories for Cj.*c 1 (period efidmj on Juac 19,
1593/GGCOZ; pll 3-2!) and C-jc2 (jisriou ;udlng -i Jane iC,
i99J/1250Z; pit 3.-I4).
29C
21C*
fibers 3. Model b.icx iri.cctoricj for Case J (period e:itiiiis an Acgvist 3,
I?Dj/D4*CZ> pll 3.6i) snd Cjie 4 (period todhig on Auguit IS,
lW3/li:3Z; pJIUO).
Figure 4. Model back trajectoro fcr C«c5 (pcfisu cading on Jane
25/tffOOZ; pll 3.4?) and Cue C [period ending on Auguir 5,
DW/WOOZ; pilJJJ).
I \ /--V
\ \ u /' r- .<*> \lX
; i A 8u/4-c:.
igtire S. Hand-analyzed back trajcctorici for Ihc 1986 field ttason.
Highlighted trajectories are those for which comparisons were
aiadc in {he (est (Yeh, 1988)'.
Figure 6. Hand-analyzed back trajectories for the 1087 field seasou.
Highlighted trajectories are !hose for which compari.sona were
made in the feit (Yeh, 1988)5.
377
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The Effect Of Anthropogenic Pollution On Cloud Microsiructure, pH and Albedo:
Case Studies and Climatic Implications
K. L. Burns, V. K. Saxena, J. C. IJIutan and J. D. Grovenstein
North Carolina Slate University
Department of Marine, Earth and Atmospheric Sciences
Box 8208
Raleigh, NC 27695-8208
ABSTRACT
In situ cloud measurements were taken during 39 individual cloud events between June and
October 1993 in Mount Mitchell State Park, North Carolina. Cloud droplet spectra were obtained using
a Forward Scattering Spectrometer Probe (FSSP) and used to determine total droplet concentrations,
average droplet radii and cloud liquid water content. The cloud water samples were collected and
analyzed for pH and chemical composition. Meteorological data were recorded and used to verify air
mass history through back trajectory analysis. A total of 119 hourly cases were available with
simultaneous FSSP spectra, pH measurements, chemical analysis and meteorological data.
A strong positive correlation (coefficient - +0.608) was detected between pH and average
droplet radius. Also, there was a strong negadve correlation (coefficient = -0.609) between pH and total
droplet concentration. The data were then sorted into three populations based on pH: pH < 3.0 (n = 20),
3.0 < pH < 3.7 (n = 75). and pH 2 3.7 (n = 24). It was observed that low pH values were associated, on
average, with higher number concentrations and lower average radii, and vice versa. Cloud albedos
were calculated for four cases and these compared favorably with the ones retrieved from Advanced
Very 1 ligh Resolution Radiometer (A VHRR). Thus, higher pollution content of clouds is shown to
produce higher cloud albedos, which hss a cooling effect on the regional climate.
INTRODUCTION
There is currently a significant amount of interest in understanding the effect of anthropogenic
pollution present in cloud forming air masses on the resulting cloud droplet sizes and number
concentrations. The desire to quantify the relationship between pollution and cloud microstructure is
fueled by the debate over global change due to the greenhouse effect. Given the recent concern over
climate change it is important that our fundamental theoretical understanding be supported by a wealth
of field data which will quantitatively describe the relevant processes.
It is well understood theoretically that low level clouds produce an indirect cooling effect by
increasing the shortwave albedo of the earth1. Increasing anthropogenic emissions can potentially
enhance ihis cooling effect by changing the cloud droplet distribution, which largely determines the
cloud optical depth and albedo. Through gas-to-particle conversion urban pollution, particularly sulfates
and nitrates, form efficient cloud condensation nuclei (CCN). In a cloud forming air mass, elevated
CCN should produce greater droplet concentration and reduced droplet size. This in turn increases the
cloud optical depth through the following relationship2.
(1)
where
P
h
N
w
cloud thickness in m
cloud droplet number concentration in m"^
cloud liquid water content in g nr^
density of liquid water (U)6 g m~3)
After calculating t, the cloud albedo can be evaluated as3
378
-------
A = T
X + 7.7
(2)
For constant cloud liquid water content, larger N implies larger optical thickness and thus larger
cloud albedo. By increasing the average cloud optical depth, elevated CCN concentrations lead to an
overall increase in the planetary albedo and hence produce a cooling effect.
It has been estimated4 that the greenhouse warming of the earth-troposphere system caused by a
doubling of carbon dioxide could be counteracted by a meager 2% increase in the shortwave albedo of
global low level cloud cover. Charlson et al.5 have estimated the current climate forcing due to
anthropogenic sulfate alone to be comparable in magnitude but opposite in sign to the current forcings
due to greenhouse gasscs. Wigley6 and more recently Saxena and Grovenstein7 have shown that climate
is more sensative to changes in SO2 emissions than to changes in CO2 emissions.
It is clearly central to our understanding of anthropogenically driven climate change to
quantitatively show differences in microstructurc and reflectivity between clouds formed in air masses
with a variety of pollution contents. By comparing these various types of clouds, we can better
determine the present anthropogenic climate perturbation, as well as make more scientific predictions of
future impacts. Although these differences are described theoretically, there is no currently available
field observational data base to provide detailed validation of the theory. Several important field studies
have been conducted that provide strong verification of many aspects of the proposed mechanisms for
pollution induced increases in cloud albedo.
During project METROMEX (Metropolitan Meteorological Experiment), Braham8 has shown
that anthropogenic effluents cause an increase in the number concentration of droplets and precipitation
in clouds formed downwind of urban-industrial regions. Alkczwccny, ct al.y have found that clouds
formed in urban plumes from metropolitan areas can increase droplet concentrations and decrease the
median volume diameter with regard to clouds formed in nearby unpolluted air masses.
Studies of the influence of anthropogenic pollution on albedo using actual measurements of
cloud reflectivity have been few and often lead to contradictory conclusions. For example, Kondrat'ycv
et al.'O, have found that city pollution lowered cloud albedo. In contrast, Radkc et al.11 have shown that
anthropogenic effluents can significantly enhance cloud reflectivity. During project FIRE |First ISCCP
(International Satellite Cloud Climatology Project) Regional Experiment! airborne measurements were
taken across ship tracks while using the Advanced Very High Resolution Radiometer (AVHRR) aboard
the NOAA-IO polar orbiting satellite to retrieve cloud reflectivities. Their results show an increase in
total droplet concentration, liquid water content and total condensable nuclei concentration within the
ship tracks compared to surrounding noncontaminated clouds. The AVHRR data showed higher cloud
reflectivity (68.3 ± 1.4%) for the ship track clouds compared with that (60.9 ± 4.5%) for the surrounding
slouds at 0.63 (lm and 3.7 Jim wavelengths. If the ship exhaust is considered as a surrogate for
anthropogenic pollution, the change in cloud reflectivity produced as a result of land-based emissions
»uld cause considerable regional and perhaps global climate perturbations.
METHOD
In situ cloud measurements were taken on Gibbcs Peak (2006 msl) in the Mount Mitchell State
Park, in rural western North Carolina. This site has several important advantages for the study of cloud
¦nicrostructure and chemistry. The site, which extends into the free troposphere, is far from local
xillution sources, allowing for the study of long range transport of both natural and anthropogenic
terosol. The site experiences cloudiness on 71% of the days during the summer12. Thus sufficient data
s obtainable in a single season to allow for stable statistics. Due to its position in mid-latitude, eastern
^orth America, the clouds passing over the site vary in origin from heavily polluted to cleaner
:ontinental and marine air masses. Recently the site has been designated a United Nations Biosphere
Jeserve so that our measurements and others can be used over a very long time span to accurately gauge
egional climate change.
Cloud droplet spectra were obtained using a Particle Measuring Systems Forward Scattering
ipectromctcr Probe (FSSP). The FSSPcan accurately count and size particles from 0.5 to 47.0 |Jm. A
'escription of the operation of the FSSP is given by Knollenberg13- Spectra were taken every 3 seconds
luring cloud events and later averaged over 5 minute and 1 hour intervals. From each 15 bin histogram
pectrum, total droplet concentration (N, m"3), average droplet radius (rave, M-m), and cloud liquid water
ontent (w, g m"3) are easily computed.
37V
-------
Qoud water samples were collected coincident with the FSSP spectra using an ASRC type
passive string impaction collector. Samples were collected continuously and retrieved hourly. On site
pH measurements were made for each sample immediately after retrieval. Samples were stored at 4°C
and later analyzed for chemical composition using a Dionex 201 Oi ion chromatograph.
Meteorological data (wind speed and direction, pressure, and temperature) was recorded and
used for back trajectory analysis using HY-SPLIT model. Forty-eight hour 3-D back trajectory graphs
were generated using 2 hour integration intervals. The model also produces skew-T diagrams for
selected times during the events. These skcw-T diagrams were used to determine cloud heights for
reflectance calculations.
Measurements were made during 39 individual cloud events between June and October 1993.
Out of this data, 119 cases were available with simultaneous FSSP spectra, pH measurements, chemical
composition and meteorological data.
RESULTS
When a cloud forms in a polluted air mass, the concentration of cloud droplets will be high, due
to elevated concentrations of CCN. Then, limited available liquid water guarantees that rave will
remain small. To investigate the relationships between pH and N and between pH and ravc. we
calculated correlation coefficients and produced scatter plots using the corresponding data pairs for all
136 available cases. Figure 1 shows pll versus droplet number concentration and Figure 2 shows pH
versus average droplet radius. As can be seen, there is a strong positive correlation (coefficient =
+0.608) between pH and average droplet radius. It can also be seen that there is a strong negative
correlation (coefficient = -0.609) between pH and droplet concentration. The coefficient of correlation
between pH and Iwc was small (0.202), therefore pH is independent of cloud liquid water content. Thus
cloud water pH is strongly influenced by both droplet size and concentration.
To investigate the dependence of pH on cloud microstructure more closely, the 119 cases with
coincident pH and FSSP data were sorted into three populations: pH < 3.0 (n = 20), 3.0 < pH < 3.7 (n =
75), and pH > 3.7 (n = 24). The average values for N, rave> lwc, and pH are shown for each population
in Table 1. The ± values represent standard errors (s/sqrt(n-1)). It is seen that low pH values are
associated, on average, with higher number concentrations and lower average radii; high pH values are
associated, on average, with lower number concentrations and higher average radii; intermediate pH
values are associated, on average, with intermediate values of both number concentration and average
radii; while liquid water contents are reasonably consistent across populations.
Four cases were selected for analysis of cloud albedo and its effect on pi I. The four cases, whic
are all short orographic events, cover a large range of pH values and thus represent clouds formed in air
masses with a variety of pollution contents. Each of the three pH populations given above is represente
by one or more cases. These events occurred on June 7,1993 (pH = 3.07), June 14,1993 (pH = 2.84),
June 18,1993 (pH = 3.77) and August 4, 1993 (pH = 3.65). For each of these cases, AVHRR data was
used to determine the cloud albedo. Using in situ measurements of cloud microstructure, a second valu
of the cloud albedo was calculated from equation (1). Since the clouds were all orographic in nature, th
clouds were all relatively thin and the heights varied by less that 15% of each other. This fact allows u:
to de-convolve the effect of cloud height, through equation (1), on the calculated cloud albedos. Thus,
the microstructural parameters, which are closely linked to pH, produce the greatest variation in the
calculated albedo values. Table 2 summarizes the cloud pH, microstructure and reflectivity for the foui
cases. There is generally good agreement between the satellite derived albedos and those calculated.
Figures 3 and 4 show, respectively, the dependence of Albedo upon N and rave for these events. The
AVHRR data set represents the satellite retrieved values while the in situ data set represents the albedo
calculated from equation (1) and (2). In figure 3 there is an obvoius positive trend with albedo
increasing as cloud droplet concentration increases. In figure 4 there is an obvious negative trend with
albedo decreasing as average droplet radius increases. Figure 5 shows the relationship between pH anc
albedo. Here the close agreement between the two albedo values is evident. The albedo is shown to
decrease with increasing pH, giving strong evidence that heavily polluted air masses develop higher
albedo clouds which produce a regional cooling effect.
CONCLUSIONS
Cloud pH, microstructure and albedo are closely related. For a given CCN composition, cloud
pH is largely controlled by droplet concentration and size, which are each controlled by the amount of
CCN present in the cloud-forming air mass. Since anthropogenic pollution produces efficient CCN, th
amount of pollution present in the cloud-forming air mass will effect the droplet distributions. Greater
levels of CCN will lead to increased droplet concentrations and smaller droplets. Because anthropogei
380
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effluents produce primarily acidic sulfates and nitrates, more pollution means lower pH. Cloud albedo
can be calculated from in situ microphysical measurements and is shown to vary inversely with pH.
Satellite measured cloud albedos closely match those calculated values. This research supports the
proposition that pollution content has a positive effect on cloud albedo. Thus, pollution is responsible
for producing regional climatic cooling by limiting the incoming solar radiation that reaches the surface.
REFERENCES
1. Twomey, 1991, Aerosols, clouds and radiation. Atroos. Environ. 1991.25A. 2435-2442.
2. Twomey, S., "The influence of pollution on the shortwave albedo of clouds," J. Atmos. Sci.
1977,24, 1149-1152.
3. Lands, A. A. and Hansen, J. E., "A parameterization of the absorption of solar radiation in the
earth's atmosphere," J. Atmos. Sci- 1974,11,118-133.
4. Ghan, S. J., Taylor, K. E., Penner, J. E„ and Erickson III, D. J., "Model test of CCN-cloud
albedo climate forcing," Geophvs. Res. Lett. 1990,12, 607-610.
5. Charlson, R. J., Schwartz, S. E., Hales, J. M., Cess, R. D., Coakley, Jr., J. A., Hansen, J. E., and
Hofimann, D. J., "Climate forcing by anthropogenic aerosols," Science 1992, 255. 423-430.
6. Wigley, T. M. L., "Could reducing fossil-fuel emissions cause global warming?" Nature, 1991,
349. 3503-506.
7. Saxcna, V. K., and Grovenstein, J. D., "Impact of changes in sulfate aerosol loading on
greenhouse warming," in Proceedings of the 1993 U.S. EPAIA&WMA International Symposium
on Measurement of Toxic and Related Air Pollutant?, VIP-34; Air and Waste Management
Association: Pittsburgh, 1993; 464-469.
8. Braham, R. R., Jr., "Cloud physics of urban weather modification - a preliminary report," Bull.
Amer. Meteor. Soc.. 1974, 55, 100-106.
9. Alkezwecny, A. J., Burrows, D. A. and Grainger, C. A., "Measurements of cloud-droplct-size
distributions in polluted and unpolluted stratiform clouds," J. Appl. Meteor.. 1993, 32,106-115.
10. Kondrat'yev, K„ Binenko, V. I. and Petrenchuk, O. P., "Radiative properties of clouds
influenced by a city," Izv. Acad. Sci. USSR Atmos. and Oceanic Phvs.. 1981,12, 122-127.
11. Radke, L. F., Coakley, J. A., Jr. and King, M. D., "Direct and remote observations of the effect of
ships on clouds," Science. 1989.246.1146-1149.
12. Saxena, V. K., Stogner, R. E., Hendler, A. H., DeFelice, T. P., Yeh, R. J.-Y., and Lin, N.-H.,
"Monitoring the chemical climate of the Mt. Mitchell State Park for evaluation of its impact on
forest decline," Tellus. 1989,41fi. 92-109.
3. Knollenberg, R. G., "Techniques for probing cloud microstructure, in Clouds: Their Formation,
Optical Properties and Effects" P. V. Hobbs and A. Depak, Eds.; Academic, San Diego, 1981,
15-19.
4. Baumgaidner, D., "An analysis and comparison of five water droplet measuring instruments," J.
aim.. 1983,22,891-910.
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Tabic 1. Population mean microphysical and chemical composition parameters for three pH
intervals. The ± values represent standard errors. The average pH for each population
was calculated by taking the minus log of the average [H+].
Number of cases
pll mi n-max
N (cm-3)
ravc (nm)
w (g m-3)
PH
[N03] (|ieq 1-1)
[S04] (neq 1-1)
pH < 3.0
20
2.51-2.99
717163
3.12 ±0.20
0.21 ±0.023
2.86 1 0.030
97.7 ±7.3
1445.71125.6
3.0 £ pH < 3.7
75
3.01-3.69
553125
3.59 ± 0.10
0.2110.014
3.2710.018
52.712S
710.4137 J
3.7 2 pH
24
3.74-4.69
281120
4.7710 JO
0.24 1 0.021
3.95 1 0.032
9.111.6
128.9114.4
Table 2. Goud pH, microphysical parameters and albedo for four orographic cloud events. The :
values for the microphysical parameters were calculated based on the suggestions from
Baumgardncr14 and the 1 values for pH represent a 5% instrument error.
June 7,1993 June 14,1993 June 18,1993 August 4,1993
N (cm-3) 7711 131 8231 140 218 1 37 226 1 38
rave (nm) 2.79 1 0.47 2.88 1 0.49 4.511 0.77 4.78 1 0.81
w (g m-3) 0.16 1 0.05 0.18 1 0.06 0.19 1 0.06 0.15 1 0.05
pll 3.07 1 0.15 2.84 1 0.14 3.77 1 0.18 3.65 1 0.18
[N03] (jieq 1-1) 45.4 40.7 24.8 24.6
[S04] (jieq l-l) 710.6 664.2 162.1 162.1
AVIIRR albedo 0.53 0.58 0.47 0.45
in situ albedo 0.54 0.59 0.50 043
382
-------
5.00 t
5.00-r
4.00-.
4.00 --
¦ ",L«» "¦ ¦' f Bt" II :¦ I
fc ___
B.00 - ¦
2.00.-
2.00-•
1.00-.
1.00-•
O.OR+OO 5.0E+08
N (/mA3)
1.0E+09
0.00
5.00
r(avc) (pim)
10.00
Figure 1. pH vs. Cloud droplet concentration Figure 2.
for all 119 coincident data pairs.
pH vs. Average cloud droplet radius
for all 119 coincident data pairs.
0.60 j
o 050-
% 0.40-¦
< 0.30-•
S 0.20- ¦
2 0.10..
** 0.(K). —
0
a
O.OOE+OO 5.00E+08
N (/mA3)
¦ AVHRR
~ in situ
1.00E+09
0.50 - ¦
0.40..
0.30 - ¦
0.20 - ¦
¦ AVHRR
~ in situ
2.00 4.00
r(ave) (|im)
6.00
Figure 3. Albedo vs. Cloud droplet concentration Figure 4.
for four orographic events.
Albedo vs. Average cloud droplet
radius for four orographic events.
0.60-r
0.50 - ¦
0.40..
0.30 ¦¦
0.20 - ¦
0.10-.
AVHRR
in situ
'igurc 5. Cloud albedos vs. pH for four orographic
events.
-------
Aerosols as a Natural Tracer of Air Masses
C. K. Deininger and V. K. Saxena
Department of Marine, Earth and Atmospheric Sciences
North Carolina State University
Raleigh NC 27695-8208
ABSTRACT
The chemical characteristics of marine, continental, and highly polluted air masses were studied by
applying principal component analysis (PCA) to the cloud water data collected during field studies at a site
located in Mt. Mitchell (2038 m MSL -35°44'05"N> 32°17'15"W) State Park, NC. The site is
particularly advantageous for studying the effects of air pollution, since it intercepts air masses arriving
from the East (marine), the West (continental), and the Northwest (polluted). PCA was used to study the
relationship between the ionic constituents of the cloud water collected and the type of air mass that forme<
tile cloud. By applying PCA to the cloud water chemistry, a set of highly intercorrelated variables was
replaced with a set of uncorrected principal components. It was found that PCA is most effective for
identifying highly polluted air masses, where the variability among the ions is the greatest. The dominant
source of the variance in continental air is the contrast between marine ions Na and CI. For clean marine
air, the variance among the different ionic constituents is minor. The sources of the air masses identified
using PCA were compared to sources of the air masses assumed from back trajectory analysis
measurements.
INTRODUCTION
Principal Component Analysis (PCA) has often been used in atmospheric research to help explair
the relationship between aerosols and their source. In 1988 Elder1 used PCA to identify the regions in thi
eastern U.S. that were the sources for S042- in precipitation. PCA has predominately been used in
atmospheric research in the identification of the sources of dry aerosols collected by filtration as Mosher
et.al.2 did in Greenland in 1993. Recently a group in Sweden used PCA to examine the differences in the
sources for interstitial and scavenged aerosols^. In this study the relationship between the ions present in
the cloud water and different types of air masses is explored using PCA. PCA of cloud water chemistry .
also used to augment existing techniques of using back-trajectory analysis and pH observation to
determine the air mass history.
Experimental Site and Instruments
The site and the measurement capabilities arc described by Saxena6 in a preceding paper in this
volume. The main instrument used for this study was the ASRC (Atmospheric Science Research Center
Albany, New York) passive string collector that collects cloud water. Cloud droplets were collected by
the Teflon strings of the ASRC in a way that is analogous to the collision-coalescence process7. The cloi
droplets that impact on the strings during a cloud event are collected in a water bottle once they become
large enough to slide down the strings. Cloud water samples were collected every hour during cloud
events and the pH of the samples was measured immediately after collection. In addition, part of the
sample was stored at 4"C for later chemical analysis.
Cloud Water Chemistry Data
Pollution sources for Mt. Mitchell were categorized into three sectors by Saxena and Ych4 using
concentrations of SOx and NO„ emissions. These sectors are shown in Figurel and are identified as
highly polluted, marine and continental. Isobaric back-trajectories using the Hysplit3 model were
calculated by UlmanS for every cloud event that was sampled during June and August of 1993. For this
study five cloud events were identified by their back trajectories as formed from air masses that were
purely continental. Similarly three cloud events were identified as marine and three were identified as
highly polluted. The back trajectories for these eleven cloud events are shown in Figure 1. To supplerm
this data, four highly polluted, six continental and five marine events were chosen from the 1986 and 19
field seasons at Mt. Mitchell. The back trajectories for these events are recorded in Saxena and I .in''.
384
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Ion exchange chromatography was used to analyze the cloud water samples. Concentrations of
cations NH4+, Na+, K+, Mg2+, Ca2+, and of anions SO42-, NO3-, and CI- were measured. By examining
the concentrations of the ions and pH of cloud water collected from highly polluted, marine and continental
cloud events Saxena and Yeh4 made the following conclusions:
• The average acidity of the cloud water is the lowest for continental air masses.
• The average concentration of sulfate, nitrate and ammonium is less for clouds of mixed or oceanic
origins when compared to clouds of urban origin.
• Higher concentrations of chloride, magnesium, potassium, and calcium are present in clouds of
continental origin.
• An ionic balance between chloride and sodium is a good indication of an oceanic source.
The average pH of the six 1993 continental cloud events identified for this study was higher than the
marine and polluted events as shown in Table 1. This supports Saxena and Yeh's first conclusion, but
the pH range was also larger for continental cloud events with the lowest pH falling lower than any of the
polluted or marine events. The average sulfate and nitrate are higher for highly polluted, but again the
range overlaps with the continental and marines events. For continental events the average calcium is
higher like Saxena and Yeh predicted, but chloride, magnesium and potassium are lower. Compared to
the continental and polluted events the ionic balance between the average chloride and sodium is good, but
for some marine events the concentration of chloride was over twice as large as the concentration of
sodium. The point is that when considering individual cloud events the relationship between the cloud
water chemistry and the source of the air mass is not always apparent. To further investigate the
relationship between the source and the history of the air masses to the cloud chemistry, we have used
principal component analysis on the cloud water data. PCA removes the correlation between highly
correlated variables such as the ions found in the atmosphere or cloud water. By removing the dependence
of the concentration of the ions on one another, we should get a clearer picture of how they are related to
the type of air mass.
Principal Component Analysis
PCA takes a set of intercorrelated variables and replaces them with a set of uncorrected principal
components. These new variables are linear combinations of the original variables. The first principal
component is the linear combination of the original variables that maximizes the variance between the
original variables. 'I"he second principal component is a linear combination of the original variables that
maximize the variance to the extent that it is uncorrelated to the first principal component. The next
principal component again maximizes the variance to the extent that it is uncorrelated with the first and
second principal component and so on. In other words, by use of orthogonal rotations a set of correlated
variables is turned into a set of uncorrelated variables. One method for finding these new uncorrelated
variables is to use the correlation matrix. If the correlation matrix is diagonal then the variables are
jncorrelated. Therefore the trick is to diagonalize the correlation matrix?. Diagonalization of a correlation
matrix is done by Finding its eigenvalues and eigenvectors. The eigenvalues and eigenvectors of a (j x j)
•orrelation matrix is found by solving the eigenvalue problem
Sa = ka (1)
vhere S is the correlation matrix, X is the eigenvalue, and a is the eigenvector. The principal component z
s then defined as
z - a'x' (2)
vhere a' is the transpose of a and x" is a standardized variable. The jth element of x* is Xj/o^w. where a is
he variance of xj the jth element of the original vector ,fl.
»CA of Cloud Water
Principal Components of the cloud water cations NlLi*, Na-», Ca2t, and of anions SO42 , NO3-,
nd CI- were found using the correlation matrices calculated from the continental, mixed, and marine
vents. K+ and Mg2+ were not included since they do not have a discernible influence on the pH. Since
.¦e have six variables it is possible to obtain up to six components. In all the events, the first two principle
omponents accounted for at least 85% of the total variance, therefore they should be sufficient for
xplaining the relations between the ions and the air mass history. The highest eigenvector in the first
-------
principal component represents the ion that best describes the variability of all the ions. NOj was the
highest eigenvector for sixteen of the thirty-seven cloud events analyzed. Table 2 and 3 represent typical
first two principal components for continental cases. In ten of the twelve continental cases a contrast
between Na and CI was indicated by opposite signs. The eigenvector for CI is positive in the second
principal component while the eigenvector for Na is negative for the example given in Table 2. The same
is true in the second example, except the signs are reversed. June 29,1993 and August 7,1993 were the
two cloud events where this contrast between Na and CI did not occur. The correlation between Na and CI
for these two events was very high. Examination of the back trajectories for the two events shown in
Figure 1, reveals that both have air masses that may have been influenced by the gulf. This influence
might account for the high correlation between Na and CI. Some variability was also accounted for by Ca,
as shown in Table 3, where Ca has the highest eigenvector for the second principal component.
NO3 accounts for the largest amount of variance in all the highly polluted events except one where
Ci has a slight larger eigenvector for the first principal component. In five out of the seven events Na has
the lowest eigenvector for the first principal component; Ca has the lowest eigenvector for the other two
events. Na and Ca, both purely natural aerosols seem to have the least influence on the variability of the
ion concentrations for the polluted events. Table 4 and 5 are examples of polluted events where Ca and Na
have the lowest eigenvectors for the first principal component and NO3 has the highest.
Table 6 gives the fust principal component for a marine event that accounts for 92% of the total
variance. For four out of the eight marine events analyzed over 90% of the total variance was accounted
for by the first principal componcnt.The first principal component accounting for almost all the variance
indicates that the ions have nearly constant values for each of the observations made for the cloud event.
Therefore the ions or original variables in these events are not dependent on one another!". In seven out
of the eight marine events analyzed Ca had the lowest or second lowest eigenvector, which indicates that it
accounts for the least amount of variance. The back trajectory for September 10,1986, the one event
where Ca did not have a low eigenvector compared to the other ions, shows the air mass starting southeast
of Florida and traversing almost the total length of the state. This air mass probably spent more time over
land compared to the other marine events, which would account for the increase in the importance of Ca.
Examination of the June 14,1993 cloud event illustrates the usefulness of combining back-
trajectory analysis and PCA to obtain a more accurate history of the air mass. The back-trajcctory for this
event shown in Figure 1 suggests this event is purely marine. Table 6 shows the first two principal
components for the event which did not follow the pattern of low variablilty among the ion concentrations
as the other marine events did. The first principal component for this event accounted for only 52% of the
total variance, with NO3 and SO4 accounting for most of the variance. The correlation between Na and Ci
for this event was 0.32. This low correlation is emphasized by the contrast between Na and CI seen in the
first principal component. Studying both the back-trajectory analysis and the PCA for this event reveals
that the air mass was influenced by both marine and polluted sources.
CONCLUSION
PCA is a very useful tool for analysis of cloud water chemistry. Although SO4 is very important
in determining the degree of acidity of the cloud water, it is NO3 that is more often the ion responsible for
the largest amount of variability. The majority of the continental events exhibited a high contrast between
CI and Na, caused by a low correlation between them. Obviously, a marine component is lacking in
continental air mass. A small contrast between Na and CI is also occasionally evident in polluted and
marine air masses, suggesting that marine aerosols are not the only source of CI. The main characteristics
of marine air are the small amount of variability among its ion concentrations and deficiency in Ca. Na an.
Ca account for the smallest amount of variability in polluted air. The most helpful ions in figuring out the
type of air mass arc Na and Ca. PCA was most effective in identifying the important factors in individual
cloud event. By combing PCA and back-trajectory analysis a more reliable technique for identifying the
sources of the air masses is obtained.
-------
References
1. Eder, B.K. Atmospheric Environment 1989 21, 2739-2750.
2. Mosher, B. W.; Winkler, P.; and Jaffrezo, J-.L. Atmospheric Rnvironment 1993 27A. 2761-
2772.
3. Noone, K J.; Ogren, J.A.; Hallberg, A.; Hansson, H-.C.; Wiedensohler, A.; and Swietlicki, E.
Tellus 1992 44B. 581-592.
4. Saxena, V.K., and Yeh, J JR. Journal Aerosol Science 198919,1207-1210.
5. Saxena, V.K.; and Lin, N.-L. Atmospheric Environment 1990 24A. 329-352.
6. Saxena. V.K. Air & Waste 1994 44.
7. DeFelice, T.P.; and Saxena, V.K. Atmospheric Research 1990 25,277-292.
8. Ulman, J.C. Air & Waste 1994 M-
9. Henry. R.C.. and Hidv. G.M.Atmospheric Environment 1979 13. 1581-1596.
10. Jolliffe, I.T.; Principal Component Analysis, Springer-Verlag New York Inc., New York, 1986.
Table 1. Summary of cloud chemistry for cloud events depicted in Figure I. |i is the mean value and
u is standard deviation.
source
NH4+
CI-
NOy
S042-
Na+
K+
Ca2+
Mg+
Jion
PH
ueq/L
ueq/L
ueq/L
ueq/L
ueq/L
ueq/L
ueq/L
ueq/
ueq/L
cont
u
3.49
208J
49.18
55.49
770.4
2756
7.21
70.86
17.8
1207.22
a
0.43
135.2
27.20
40.48
515.7
26.90
6.15
81.82
16.8
794.49
pH range
2.49-3.99
marine
n
3.37
165.8
70.60
48.90
478.0
65.33
12.03
2439
21.7
886.91
a
0.28
128.1
65.95
36.74
327.0
60.69
6.37
15.29
18.0
740.74
pH range
2.99-3.74
polluted
M
3.18
296.1
53.65
82.48
1070.
19.73
7.42
43.85
15.0
1588.76
a
0.17
77.98
18.02
28.14
253.8
18.87
3.80
20.70
5.44
326.90
pH range
2.95-3.34
387
-------
Table 2. Principal Components for continental event August 17,1993.
S042-
NO3-
CI
Na+
Ca2+
nh4+
percent variance
0.43
0.43
0.31
0.41
0.43
0.43
88%
-0.07
-0.06
0.92
-0.34
-0.10
-0.12
9%
Table 3. Principal Components for continental event July 10,1986.
S042-
NO3
a-
Na+
Ca2+
nh4+
percent variance
cumulative
0.44
0.44
0.44
0.41
0.22
0.45
78%
78%
-0.21
-0.16
-025
0.02
0.92
0.13
15%
93%
Table 4. Principal Components for polluted event June 24B, 1993.
SO42-
NO3-
a-
Na^
Ca2+
nh4+
percent variance
cumulative
0.42
0.47
0.46
0.14
0.39
0.46
69%
69%
0.23
-0.12
0.19
0.85
-0.37
-0.22
18%
87%
Table 5. Principal Components for polluted event October 12,1987.
SCM-
N03
CI-
Na+
Ca2+
nh4+
percent variance
cumulative
0.36
0.47
0.47
0.44
0.24
0.41
67%
67%
-0.55
-0.20
-0.09
0.28
0.75
0.08
20%
88%
Table 6. Principal Component for marine event May 14,1987.
SO42- NOr CI- Na+ Ca2+ NH4+ percent variance
1 0.41 0.42 0.42 0.42 0.34 0.42 92%
Table 7. Principal component for marine and polluted event June 14,1993.
SO42-
NO3-
Cl-
Na+
Ca2+
NH4+
percent variance
aimulativ
0.54
0.57
0.08
-0.03
-0.28
0.55
52%
52%
0.11
0.02
0.40
0.67
0.59
0.16
34%
86%
388
-------
Figure 1 Back trajectories for continental, marine and highly polluted events from 1993. Each
trajectory is identified by the month and day it occulted.
8.19,
8,5
•?.
-------
Greenhouse Warming. Acidic Deposition, and the Dilemma of Climate Change
by
J.D. Grovenstein and V.K. Saxena
North Carolina State University
Department of Marine, Earth and Atmospheric Sciences
Raleigh, NC 27695-8208
ABSTRACT
Tropospheric aerosols produce climatic perturbations through direct and indirect contributions to
radiative forcing. Sulfate aerosols produce a cooling effect by elevating concentrations of cloud
condensation nuclei (CCN) which enhance cloud-mediated albedo. Results from an ongoing field studv at
Mt. Mitchell, NC (35' 45'5" N, 82' 17' 15" W. 2,038 m or 6,684 ft MSL) are presented. In response to
the serious environmental problems due to acidic deposition, the Clean Air Act was amended mandating
the reduction of fossil fuel emissions. Results presented here indicate a reduction in fossil fuel emissions
that reduce acidic deposition could exacerbate greenhouse wanning. Cloud reflectivity measured by the
satellite based Advanced Very High Resolution Radiometer (AVHRR) from clouds with contrasting
inicrophysical characteristics show varying radiative properties. This variation implies that the impcet of
enhanced CCH concentration on the temperature of the earth-troposphere system cannot be evaluated
without accounting for the role of clouds in the same system.
INTRODUCTION
In an attempt to mitigate the serious environmental problems of global wanning and "acid ruin , die
Amended Clean Air Act has mandated the reduction of both CCb and SCh. The Amended Ciean Air Act
may actually exacerbate the magnitude of global wanning while solving the dilemma of acid rain.
The role of SO2 in 'he formation of hygroscopic nuclei is well known as is their capability of
increasing the reflectivity of low level clouds. 1-2,3 Th-s increase in reflectivity in turn produces a cooling
effect on the earth-troposphere system. The cooling effect may be significant enough to counteract
greenhouse warming on a regional basis due to non-uniform distribution of sulfate aerosols. If sulfate
cooling is currently counteracting greenhouse wanning, reduction of SO2 as mandated by the Clean Air
Act will counteract, cooling due to SCh. The concentration of CO?,, however, will continue to rise for mor<
than a century even if emissions are kept constant at present levels. It is known that an increase in the
number concentration of cloud droplets causes an increase in the cloud lifetime and the cloud reflectance.
Measurements such as those made under Project METROMEX (Metropolitan Meteorological Experiment)
during the seventies have demonstrated that anthropogenic effluents cause an increase in the number
concentration of droplets and precipitation in clouds formed downwind of urban industrial regions.4
However, it is not known what effect such effluents have on the shortwave albedo of these clouds.
Modeling studies have shown that increases in the background pollution concentrations, in particular ihost
that act as Cloud Condensation Nuclei (CCN), will result in changes in cloud reflectivity and
cvolution.^.6,7
By observing the microphvsico-chemical characteristics of both clouds and aerosols in clean and
highly polluted air masses at Mt. Mitchell, NC (35', 45'5" N, 82', 17'15" W. 2038 m or 6684 ft MSL)
the impacts of anthropogenic and natural tropospheric aerosols on the regional cloud reflectivity may be
investigated by simultaneously analyzing cloud reflectivity data derived from the Advanced Very High
Resolution Radiometer (AVHRR) aboard the NOAA spacecraft. The following features make Mt. Mitche
(designated as a United Nations Biosphere Reserve) a "barometer" for monitoring regional climate change
• die mountain encounters cloud 71% of days during the summer, on the average.
• the air masses arriving at the mountain could be highly polluted continental (pH of cloud water
2.2) or clean maritime (pi I of cloud water =¦ 5.4) depending on the prevailing wind fieiri.8-9
• rates of cloud deposition were found to be in the range of 15-27 cm yr1.The deposition flux
of sulfate ranged from 26-82 kg ha"5 yr1.
METHODOLOGY
An intensive field campaign to Mt. Mitchell began on May 1.1993. Besides meteorological
measurements (Temperature. Pressure, Relative Humidity, Wind Speed and Direction) atop a 56 ft. (16..'
-------
m) tall walk-up tower, the following observations were recorded: CCN activation spectrum (using
Fukuta-Saxena CCN Spectrometer), cloud droplet size distribution (Forward Scattering Spectrometer
Probe), and pH and ionic content of cloud water (collected by a passive collector and analyzed by Dioncx
system).
Cloud reflectivity is derived from the AVHRJR instrument aboard the NOAA spacecraft. Raw
AVHRR pass data containing channels 1 through 5 is processed into a 1024 x 1024 pixel stibscene
centered over Mt. Mitchell. Cloud reflectivity in the visible (0.63 f-im) and near-lR (3.7 pm) are derived
for daylight passes. Cloud reflectance at 0.63 (im depends on cloud thickness, liquid water content and
droplet size. Cloud reflectance at 3.7 Jim is controlled by droplet size alone. Cloud emissivity (3.7 (J-tii.) is
derived for nighttime passes. Cloudy pixels in the vicinity of Mt. Mitchell arc analyzed for reflectivity or
.emissivity depending on the time of day. Care is taken to exclude pixels that are contaminated by ice or
contain fractional cloud elements.
RESULTS
Simultaneous analysis of AVHRR data and microphysico-chcmical characteristics of clouds and
aerosols during the period of June-October, 1993 (listed in Tables 1 and 2) have yielded the following
evidence:
1) There is a strong relationship between visible cloud reflectance (0.63 |itn) and ihe cloud droplet
number concentration and pH of the cloud. In general, larger cloud droplet number
concentration and lower pH (higher acidity) lead to a higher visible reflectance. The pH and the
visible reflectance of the cloud (Fig. 1) are found to be strongly correlated (correlation coefficient
= 0.98).
2) There is a strong relationship between cloud emissivity (3.7 urn) and cloud pi 1, cloud droplet
number concentration, cloud droplet radius. In general, larger ciond droplet concentration,
higher acidity (lower pH), and smaller cloud droplet radius lead to lower emissivity values. The
pH and the emissivity (3.7 |im) of the cloud are found to be strongly correlated (correlation
coefficient = 0.71).
3) The CCN number concentration at 1% Supersaturation in the air mass were found (listed in Tabic
2) to influence the emissivity of the ensuing clouds. In general, larger CCN concentrations lead
to smaller emissivity values.
4) There is no relationship between the liquid water content of the cloud (listed in Tables 1 and 2)
and the visible reflectance (0.63 }im) or emissivity (3.7 jim) of the cloud.
CONCLUSIONS
It is becoming increasingly apparent that the warming of the earth-troposphere system induced by
greenhouse gases could be counteracted regionally by an increase in the cloud cover and/or cloud
reflectivity.''>12,13 results presented here illustrate the potential for analysis of clouds fur
microphysical effects at Ml. Mitchell and complement other studies of marine stratus clouds J 4,15
::loud systems are complex and conclusions about the relationships between cloud microphysical
:haracteristics and clond reflectivity will require careful statistical analysis of robust, long term datasets.
3ur first year observations followed by preliminary data analysis lead to the following inferences:
1) Clouds formed by dean air masses with higher pH (lower acidity) tend to have lower v isible
reflectances and higher emissivities.
2) Clouds formed by polluted air masses with lower pi I (higher acidity) tend to have higher visible
reflectances and lower emissivities.
("he consequences of an emissions specific control policy intended to reduce global warming or acid rain"
ould be to enhance global warming. Removal of SO2, and thus the hygroscopic nuclei formed by SO2,
vould remove any cooling effect on the earth-troposphere system. Observed increases in the number
oncentration of cloud droplets formed in polluted air masses indicate a cooling of 2-3 Wm •' in eastern
Jorth America due to increased reflectivity of clouds. 12 These values are comparable to the estimated 2.5
Vin'- healing due to anthropogenic greenhouse gas emissions up to the present.' 6 Model studies have
alculatcd that a four fold increase in marine CCN concentrations could counteract greenhouse wanning of
391
-------
the earth-troposphere system caused by a doubling of CO2Climate models have shown significant
climatic response whenever cloud-related parameters have been varied, especially with effective radius of
cloud droplets J
The data here have, shown the radiative properties of clouds varying with differences in cloud
inicrophysico-chemical characteristics; however, knowing the present radiative properties of clouds does
not indicate the response of the regional climate to changes in cloud microphysico-chenucal characteristics.
The sensitivity of the climate system to changes in cloud radiative properties must be investigated before
any strong conclusions may be drawn.
Acknowledgments:
This work is supported through the Southeast Regional Center of the National Institute for the
Global Environmental Change by the U.S. Department of Energy under cooperative agreement No. DE-
FC03-90ER61010.
REFERENCES
1. Twomey, S.A.; Attires. Environ.. 1974 S. 1251-1256.
2. Twomey, S.A.: J. Atmos. Sci.. 1977 34, 1149-1)52.
3. Twomey, S.; Piepgrass, M; Wolf. T.L.: Tellus. 1984 36B. 356-366.
4. Braham, R.R.; Bull. Amer. Meteor. Soc.. 1974 55, 100-106.
5. Raga, G.B.; Jonas, P.R.: Q.J.R. Meteorol. Soc., 1993 H9, 1419-1425.
6. Ghan, S.J.; Taylor, K.E.; Penner, J.E.; Erickson, D.J., III; Geophvs. Res. Lett.. 1990 17, 607-
610.
7. Slingo, A.; Nature, J990 243, 49-51.
8. DeFclice, T.P.; Saxena, V.K.; J. Atmos. Sci.. 1990 47, 1117-1126.
9. DeFelice, T.P.; Saxena, V.K.; J. Appl. Meteor.. 1991 2Q- 1548-1561.
10. Saxena, V.K.; Lin, N.H.; Atmospheric Deposition, International Association for Hydrologicai
Sciences, IAHS Publ. No. 179; Available from; Instiwte of Hydrologv, Waling Ford. Oxon ox 10
8BB, England, 1989; pp 193-202.
11. Wigley, T.M.L.; Nature. 1991 242, 503-506.
12. Uaitch, W.R.; Isaac, G.A.; Strapp, C.M.; Wiebe, H.A.; J. Geophvs Res.. 1992 92, 2463-2474.
13. Twomey. S.A.; Atmos. Environ.. 1991 25A. 2435-2442.
14. Radke, L.H.; Coakley, J.A., Jr. King, M.D.; Science. 1989 246. 1146-1149.
15. Platnick, S.; Twomey, S.; J. Appl. Meteor.. 1994 33. 334-347.
16. Shine, K.P., Derwent, R.G., Wuebbles, D.J., et al.; Climate Change, The H'CC Scientific
Assessment, J.T. Houghton, G.L. Jenkins and J.J. Ephraumas, Eds., Cambridge Universitv Press,
1990; pp 41-68.
39?.
-------
Table 1. Cloud microphysico-chemical properties with corresponding daytime
Visible (0.63 |ixn) and Near BR (3.7 nm) reflectances.
Date
Time
pH
N
r
lwc
Visible
Near IR
Temp.
1993
(UTC)
(cnr3)
(nm)
(gnr3)
Albedo
Albedo
(O
June 14
2147
2.84
823
2.88
0.18
57.5
18.5
19
June 7
2132
3.07
771
2.79
0.16
53
13
11.2
June 18
2058
3.77
218
4.70
0.24
47
11
13
Aug 4
1415
3.65
226
4.78
0.15
45
19
12
Table 2. Cloud microphysico-chemical properties with corresponding nighttime
emissivity (3.7 jim) values.
Date
1993
Time
(UTC)
pH
N
(cm-3)
r
(|im)
lwc
(gm"3)
Emissivity
CCN
(1% S)
(cm-3)
Temp.
(O
Aug 18
0013
2.97
750
3.22
0.16
0.672 ± 0.022
1100
13
Aug 19
1024
3.08
634
4.08
0.27
0.77: ± 0.052
1200
11.7
Aug 24
0125
3.24
515
4.37
0.27
0.848 10.052
600
10
Aug 06
0942
3.79
462
4.93
0.3
0.863 ± 0.053
200
19
Oct 03
0940
4.74
54
8.3
0.29
0.875 ±0.013
NA
6
393
-------
65
June 14
June 7
55
6
ro 50-
to
d
June 18
Aug 4
40
2.5
3.0
3.5
4.0
PH
Figure 1. Cloud visible (0.63 pm) reflectance values vs. cloudwater pH. Error bars represent staackrd
errors of pixel values averaged in the vicinity of Mt. Mitchell.
394
-------
1.0
Aug 24 Aut9 6
0.9-
Oct 3
Aug 19
>
0.8-
<2
E
LlI
0.7-
Aug 18
0.6
2.5
3.0
3.5
4.0
4.5
5.0
PH
Figure 2. Cloud emissivity (3.7 pm) values vs. cloudwater pH.
395
-------
SAGE II Based Column Surface Area Measurements of the Mt. Pinatubo
Aerosol Over the Eastern United States
John Anderson and V. K. Saxcna
Department of Marine, Earth & Atmospheric Sciences
North Carolina State University
Raleigh, NC 27695-8208
ABSTRACT
Since the increase in anthropogenic chlorine is estimated to be about 30-40% in the last 12 years,
the eruption of Mt. Pinatubo during June 12-16, 1991 has the potential to possess the surface areas needed
tor the destruction of ozone on a large scale since it is the laigesl volcanic event recorded in recent history.
The Pinatubo aerosol characteristics between 12-30 km and columnar characteristics in a unit column
between 15 25 km are inferred from the Stratospheric Aerosol and Gas Experiment (SAGE) II
measurements using a Randomized Minimization Search Technique (RMST) in the radii range of 0.1 0.8
in 0.1 jtm increments. Results between 1991-94indicate that the maximum surface areas observed
wcrciipto/18«m2eirr3. The vertically averaged surface areas of up to 28/
-------
SAfilC II Data Base Description
NASA's SAGE II program has provided dependable stratospheric aerosol extinction measurements
since the programs inception in October 1984. The SAGE II instrument is a self calibrating, limb scanning
sun photometer on board the Earth Radiation Budget Satellite (ERBS) that measure* vertical prol'sles of
aerosol extinction coefficients at wavelengths of 1.02. 0.525, 0.453. and 0.385 / ?-)nr2n(r)dr
where
Q - extinction efficiency factor for.Vlie particles
m, - refractive index
r - particle radius in imi
n{r) - number concentration in c in': fun' between particle radius rand r +dr.
The RMST is a spectral inversion technique designed to find a size distribution whose optical properties
have a minimum deviation from the measured properties. This deviation is quantified by a nxit-niean-
square deviation. In ihi* ca.se, Ihe RMST process is applied to the extinction coefficients provided by
the SAGE II piogram at the four wavelengths X (number of equations). To determine the inversion size
interval, the ratio criterion of kernel functions is applied to the respective wavelengths. The latiocriteiion
slates that if the ratios of kernel functions at different wavelengths remain constant in some size ranges, the
information content cannot be provided in those ranges. To apply the RMST inversion algorithm, eight
size interv als (number ol' unknowns) are selected w ith the middle points from 0.1 - 0.8y.m by 0.1 ; 0.8 /i/c intervals cannot be resolved by RMST. The Junge size distribution is used as un initial assumption to
expedite the calculations. The aeiosol particles are assumed to be comprised of a 75'.v sulfuric acid
;i IiSO.i) and 25"/<. water (H^O) solution leading to an aerosol density of 1.65 g cm The refractive
nde.x tor Mic particles used in the calculations is 1.45. Numerous inversion algorithms have been devised
o invert spectral data. The main advantages of using RMST over other inversion algorithms aie: 1) it is
elatively fast. 2) no piesumcd size distribution is necessaiy, 3) RMST's ability to depict multimodal
listnbutions, 4) smoothing and non-ncgativc constraints, 5) no closure constraints (unknowns do not
lave lo equal to the number ol equations). The particular data base constraints arc in essence. RMST's
:ons train Is The efficacy of RMST was proven for the analysis of the. severe ozone depletion episode over
\ntarctica during 1987 (12). In this study, columnar aerosol properties such as total number Nctcnr-),
nass loading Me (nig ill"3), surface area Sc (^m2cm -), and mean
-------
DISCUSSION AND RESULTS
Tables 1 and 2 show the vertically av eraged and maximum aerosol characteristics for each height
between 15-25 km and 25"-45° N, 60°-80° W (i.e. the eastern U.S.), for January 1991 and February 1992
respectively. The January 1991 profiles depict the unperturbed background stratospheric aerosol
characteristics. The presence of the Pinatubo aerosol is clearly evident in the 1992 profiles as the number
concentration N increased by up to 10 times, the mass concentration M increased by up to 50 times, and
the surface area concentration S increased by up to 25 times greater than the background levels in January
1991. The optically thickest layer appears to be between 18-22 km. Maximain Not 173.8 cm-3 is found
at 18.5 km, whereas S of 40.37 cm"-1 and M of 8.45 jig nr3 are found at 19.5 km. The averaged
peak value of N is 57.96 cm 3 at 20.5 km wheieus the averaged peak values of S and M are 23.66 jtm-
enr3 and 5.19 ft a nr3 respectively at 18.5 km. These observations suggest a greater concentration of
smaller particles at 20.5 km. It must be stressed that these calculations arc conservative estimates due to
the large number of truncated measurements below 20 km and the retrieved si/e interval in that particles
with r < 0.1 ]sm and r > 0.8 cannot be included in the calculations. 1'he effective radius Re (not
shown) is the total volume to total surface area ratio and is helpful in determining the contribution of the
larger particles. Values of Re ranged between 0.29 )*m at 24.5 km to 0.42 at 19.5 km compared to 0.14
um and 0.18 / 0.8 y/m may be present in Figures lb) and 1c). The 2'93 and
7/93 profiles can also be fitted with the sum of 2 lognormal functions. It is evident that the smaller radii
intervals in Figure Id) for 7/93 are approaching the background levels of 1/91. Larger particles are still
present but smaller in total number. This can be attributed to the decay and sedimentation of the aerosol.
Table 4 shows the temporal history of the derived columnar aerosol characteristics over the eastern
United States. Major increases in the derived characteristics are clearly evident in November 1991. The
aerosol maintained columnar surface areas 011 the order of 100xl05/ 0.3 //m). The
maximum surface areas coincided with the most optically thick layers. The surface areas, mean radii, and
total number concentrations remained virtually constant through February 1993. A decrease on the order
of 2 is evident between February and July 1993 for the derived characteristics Nc. Mc and Sc as the
aerosol coagulates and settles into the lower stratosphere. The observ ed column surface areas between
July 1992 to February 1993 arc 50-lOOxlO5 ^m2 cm 2 and roughly coincide with record losses o! ozone
between 12-22 km (7). The eff ective radii Re during this same interval ranged from 0 32-0.40;
-------
CONCLUSIONS
Columnar aerosol characteristic1; between a unit column of 15-25 km and mean aerosol
characteristics between 12-30 km were inferred from SAGE II measurements between 25° 45° N and 60°-
100° W . These characteristics were studied over time from 1991 to the present. The following
conclusions result from this study:
1) Columnar bi-modal size distributions were prevalent from late July 1991 to July 1993 with small mode
radii of less than 0.1 and large mode radii between 0.3-0.6 ftm.
2) Vertically averaged surface areas were prevalent on the order of 10-26 jAm2 cm"3 with maximums of up
to 46 kiii2 enr3 at individual layers between November 1991 to July 1992.
3) Columnar bi-modal distributions with small mode radii approaching the background levels and large
mode radii on the order of 035 ftm arc observed in March 1994 as the aerosol decays and settles. A larger
mode with radii > 0.6 fjm may be present.
4) Mean surface areas on the order of 1-28 pivefl cm-3 with maxima between 6-48 j-trn1 cm 3 were present
and coincided with record losses of ozone over the United States between 12-22 km in February 1993.
ACKNOWLEDGEMENTS
This work was supported by NASA Langley Research Center under contract NASI-1894-1. One
of us (V.K.S.) is indebted to M. Patrick McCormick for making him interested in SAGE II.
REFERENCES
1. McCormick. M. P.; Viega, R. E.; Geophvs. Res. Lett., 1992 ]9, 155-158.
2. McKeen, S. A.; Liu. S. C.: Kiang. C. S : J. Geophvs. Res.. 1984 89. 4873 4881.
3. Chandra, S.; Geophvs. Res. Lett. 1993 20, 33-36.
4. llofmann. D. J.; Solomon; J. Geophvs. Res., 1989 94, 5029-5041.
5. Schoeberl, M. R.; Bhartia, P. K.; I lilsenrath, K.; Oeonhvs. Res. l*tt. 1 99 3 20, 29-32.
6. Grant, W. B ; Fishman, J.; Browell, E. V ; et al.; Geophvs. Res. I-ett.. 199219, 1109-1112.
7. Hofmann, D. J.; Oltmans, S. J.; Komhvr, W. D.; et al ; Geophvs. Res. Lett.. 1994 2_L 65-68.
8. Brasseur. G.; Granier, C.; Science. 1992 257, 1239-1242.
9. 1'rathcr. M., J. Geophvs. Res.. 1992 97, 10187-10191.
10. Mauldin, L. E. Ill; Zaun, N. II.; McCormick, M. P.; et al ; Opt. Eng.. 1985 24. 307-312.
11. Heintzenberc. J : Muller, H : Quenzel, H.; et al ; Appl. Opt. 1981 20, 1308-1315, 1981.
12. Lin, N. H.; Saxena, V. K.; J. Geophvs. Res.. 199 2 97, 7645-7649.
13. Deadlier. T.; Hofmann. D. J.; Johnson, B. J.; ct al.: Geophvs. Res. Lett., 1992 19, 199-202.
14. Deschlcr, T.; Johnson, B. J.; Rozier, W. R.; Geophvs. Res. Lett.. 1993 20, 1435-1438.
399
-------
Table 1. Vertical profiles of averaged and maximum (max) aerosol
characteristics between 15-25 km from 25°-45° N and 60°-80° W
during January 1991.
N(rm"^)
N'max
Mman
S(^m2 cm"3)
Smax
15 6
4.01
16.26
0 12
0.22
0.96
2.45
16 5
5.57
19 12
0 13
0 23
1.19
2 85
15
4 71
23.78
0.13
0.27
1.10
3 56
IS 5
5 40
17.24
0.12
0 21
1.13
2 60
10 5
5.82
15.75
o.n
0.17
1.13
"* 2 7
2C.5
5.62
17.3J
0.09
0 15
1.04
2.38
21 5
4.50
14.21
0 07
0 13
0.82
1 91
22 5
3.68
1 2 64
0.06
0 1 2
0.67
1.74
23 5
2.47
116",
0 04
0 10
0.48
1.55
24 5
2 78
12 17
0.04
c 1
o'
0.47
1.68
Table 2. Vertical profiles of averaged and maximum (max) aerosol
characteristics between 15-25 km from 25°-45" N and 60"-80" W
during February 1992.
Iteiehtfkm;
Nr(cm 3)
Nmax
M0n; m 3>
Mm~s
—v —T
Slumnar aerosol characteristics in a unit column between 15-25 km from 25°-45" N and
60°-80" W. The Re and Rm are averaged columnar properties.
Mc:.lhh) u:id Vcai
KUcnr2).\1C5
Mc(mfc in*A>
Stijrfm
2 un'2h\105
KnV,^:u)
.Uiu;:rv 1991
50.1
0 90
9,1
o : l
0.17
."unc'Julv 1991
84.3
1.2
14.4
0.12
0.16
November 1991
25*
19.6
100
0 16
0 29
F<^t nu y 1992
236
23.0
108
0.21
0 38
.'illy 1992
:93
21.6
95.2
0.19
0 10
Tehr.aiv 1993
190
14 6
71.0
0 13
0.32
.l.ily 1993
1 06
7 5
38.1
0 14
0 3 l
Mafv;i 1991
33.8
2.7
14.9
0 16
0.30
400
-------
£
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Figure 1, Comparison of the mean unperturbed Januaiy 1991 and volcanically perturbed a) February
1992, b) July 1992, c) February 1993, and d) Julv 1993 column number distributions
between 25°-45° N and eO'-SO" W in a unit column from 15-25 km. The error bars
represent 1 standard deviation.
401
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SESSION 8:
MEASUREMENT METHODS
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Intentionally Blank Page
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A Study of Interferences in Ozone UV
and Chemiluminescence Monitors
E.JB. Hudgens and T.E. Kleindienst
ManTech Environmental Technology, Inc.
P.O. Box 12313
Research Triangle Park, NC' 27709
F.F. NlcElroy
Atmospheric Research and Exposure Assessment Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
W.M. Oliison
American Petroleum Institute
1220 L Street, N.W.
Washington, D.C. 20005
ABSTRACT
A study was conducted to examine interferences and other measurement anomalies in
chemiluminescence and ultraviolet ozone monitors. Previous results had shown that there was a positive
deviation in the chemiluminescence monitors and no direct interference with ultraviolet monitors due to
the presence of water at non-condensing concentrations. The present study continues this effort,
examining both potential positive and negative effects of moisture and other interferences on these
monitors. Aromatic compounds and their oxidation products could potentially show a positive
interference with ultraviolet monitors, and test measurements were made with aromatics such as toluene,
benzaldehyde, and nitrotoluene to determine their possible retention in the ozone scrubber and their
absorption in the cell as a function of the humidity. A detailed examination of the scrubbers used in
ultraviolet ozone monitors has also been undertaken. Ozone scrubbers that have shown anomalous
behavior in the field have been studied in various reduced-efficacy modes under controlled laboratory
conditions. Longer term tests of unused scrubbers for possible ozone breakthrough under exposure to
various simulated field conditions were initiated.
This paper has been reviewed in accordance with the U.S. Environmental Protection Agency's
peer and administrative review policies and approved for presentation and publication. Mention of trade
names or commercial products does not constitute endorsement or recommendation for use.
405
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INTRODUCTION
Ozone is formed in the atmosphere from photochemical reactions involving hydrocarbons (HCs)
and oxides of nitrogen (NO*). Adverse health effects and plant damage occur at high ambient
concentrations. The Clean Air Act directed states and local pollution districts to monitor ambient ozone
concentrations. Currently, many areas of the country are not in attainment of the national ambient air
quality standard (NAAQS) for ozone. Therefore, accurate measurement of atmospheric concentrations
is important because small differences in measured maximum ozone concentrations can change an area's
nonattainment classification and profoundly affect its control strategies.
Current measurements of ozone use continuous monitors based on principles of
chemiluminescence (CL) or ultraviolet (11V) absorption. The most prevalent chemiluminescence
technique utilizes the reaction of ozone with ethylene, whereas the absorption approach uses the UV
absorption of ozone at 254 nm. Because of its inherent instability, no primary ozone standards are
available. NIST-traceable ozone standard monitors are available for accurate instrument calibration.
Ambient interferences can cause significant ozone measurement errors with some types of monitors. This
study investigates the role of water vapor and some aromatic photochemical pollutants in the measurement
of ozone by chemiluminescence- and ultraviolet-based instruments. These results could have implications
regarding the selection of the type of ozone monitoring instrument used in specific areas and the accuracy
of the monitoring data obtained.
While most monitoring agencies in the US have had no apparent problems, measurement
anomalies have been reported to the U.S. EPA by some local and state agencies. The response of both
types of monitors to high levels of humidity has been questioned.1 Also, the behavior of the scrubber
canisters used in UV monitors to remove ozone from the sample (for zero reference) is not known. In
order to test these monitors under controlled conditions, a manifold system capable of producing stable
and known amounts of ozone, humidity and a variety of possible interferants was constructed. The
current study has been designed to systematically examine the effect of various levels of absolute humidity
on the response of several commercially available chemiluminescence and UV ozone monitors. In
addition, the potential interference in UV instruments due to individual aromatic compounds present in
ambient urban air has been examined.
EXPERIMENTAL METHODS AND PROCEDURES
A Teflon and glass manifold system was designed to fulfill the objectives of this study. The
system, shown by the schematic in Figure 1, has been described previously2. The only recent
modification to this system has been the addition of a controlled inlet for the introduction of individual
test compounds. Teflon source bags of these potential interferants were made from the same air source
used to supply the manifold. The dilute test compounds could be introduced directly into the monitors
or they could be added to the mixing manifold via a peristaltic pump. By using this system, the
humidity, temperature, ozone and test compound concentrations remained extremely stable during
experimental runs.
Several ozone monitors were used during the course of the study, but no more than six were
tested at any one time. While the set of monitors tested do not represent the entire range of monitors
available, they are probably representative of commercially available monitors, since the vast majority
operate on the same principles. The UV instruments included two Dasibi Mode! 1003AH monitors
(denoted in the text as DaOJl and Da032), one Dasibi Model 100BAH monitor (Da08), two Teco Model
49 monitors (Tecol and Teco2), and one Monitor Labs 9811 monitor (ML 9811). The UV instruments
measure the difference in the ultraviolet radiation absorption of a low-pressure mercury UV source (254
406
-------
nm) between the sample air and the sample air with ozone removed (or scrubbed). Ozone scrubbers in
the analyzers generally consist of wire screens (or other media) coated with manganese dioxide enclosed
in a canister through which the sample flows during half of the analysis cycle. The chemiluminescence
monitors included a Bendix Model 8002 (Bendix) and a Monitor Labs Mode! 84IO(ML84tO) instrument.
Chemiluminescence occurs as a result of the reaction of ozone with ethylene, which is thought to generate
an excited formaldehyde molecule through a minor pathway. The broadband emission with a maximum
of 440 nm is detected by a con%'entional photomultiplier tube.
Ozone mixtures were also generated in a photochemical (i.e., smog) chamber from irradiations
of hydrocarbon (HC)/NOx mixtures. The reaction chamber is 23 m' in volume and constructed of 5-mil
Teflon film. A series of blacklights and sunlamps, which surround the cylindrical chamber, were used
to simulate sunlight in the near U V spectral region. Samples for chemical analysis were taken from ports
attached to the aluminum endplates. Other details of the chamber have previously been described5.
Ozone calibrations were carried out by using a separate Dasibi Model I003A1I ozone monitor
as a secondary (transfer) standard. This Dasibi ozone monitor was calibrated against U.S. Environmental
Protection Agency (EPA) Standard Reference Photometer (SRP) #7, which is directly traceable to the
standard ozone photometer operated by the National Institute of Standards and Technology (Is'IST). The
calibration curve generated from the Dasibi transfer standard showed extremely good linearity (if3 =
0.999992), and the resulting calibration cum* was virtually identical (within 0.5%) to that obtained from
previous calibrations against the SRP.
All of the monitors used in the study were calibrated against the standard Dasibi monitor by using
the manifold system with ozone in dry zero air. Before the calibration, each of the monitors was adjusted
for sample and reactant gas flows and electronic offset according to instructions given by the user
manuals. During the calibration, 30 readings were taken from each of the instruments at five ozone
concentrations between 0 and 400 ppbv. The monitor readings were then plotted against the true ozone
concentrations, as determined from the standard Dasibi monitor. Calibration curves were generated for
each of the instruments. The linearity of each of the instruments was excellent, giving if values between
0.999984 and 0.999998. These multipoint calibrations were performed as necessary during the study.
For experimental measurements made with humid air or test compounds, the monitors were
zeroed and spanned using dry dilution air immediately before and after the complete series of
measurements each day. These measurements simply served as checks and were not used in subsequent
calculations. When humid air was required, the dilution flow was directed through the water bubbler.
Due to evaporative cooling, an external heat source (i.e., heating tape) was required to maintain the liquid
reservoir at constant temperature. Ozone/humid-air flows were allowed to equilibrate for at least an hour
before measurements were made. The readings from the monitors were entered into a spreadsheet
template containing calibration information to generate absolute ozone measurements. In addition, all
monitors were connected to individual chart recorders to provide a visual depiction of the stability of the
system.
During efforts to examine the effect of condensed water on the monitors, the entire manifold
system was heated to a temperature approximately 5 CC above ambient temperature. The monitors aud
sampling lines were maintained at ambient temperature during these experiments. All procedures were
identical to those above, but data were obtained only with chart recorders.
As part of the study, HC/.NOx mixtures were irradiated in a smog chamber to generate ozone
photochemically. Two different irradiated hydrocarbon mixtures, which have previously been used as
407
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surrogates for urban atmospheres,3 were used to measure instrument and scrubber performance. The
residence time in the chamber (10 hours) was selected so the concentration of ozone in the effluent was
120 - 150 ppbv. The major components measured during the irradiation included reactarit hydrocarbons,
organic and inorganic NOx compounds, nitric acid, carbonyl compounds, and ozone. Selected carbonyls,
dicarbonyls, other organic oxygenates were quantified. During the scrubber tests, the canisters were
exposed to the smog chamber effluent continuously for 13 weeks. The flow through each scrubber was
1 L/min which is similar lo the expected average flow for a normal monitor in the field. Both new
scrubbers and used scrubbers reported to have previously malfunctioned (anomalous scrubbers) were
tested for ozone breaktlirough by placing the canisters in the sampling line of a ehemiluminescence
monitor, exposing the canister to various amounts of humidity and NO? at 200 ppbv ozone, and
monitoring for ozone breakthrough. NO, was selected since it represents one of the most widespread
inorganic pollutants found in photochemical smog and is generally found with ozone in moderate
concentrations.
In another set of measurements, individual aromatic compounds were added lo the manifold in
the presence and absence of ozone to measure, potential interferences. In these measurement, l)V
monitors were used in two configurations. Figure 2 shows the two different configurations for the Dasibi
1003-AH monitors. The bypass configuration was used for absorbance measurements of potential
interferants. With this arrangement the absorbance of the test compound in the sample was measured
against a known clean air reference. The normal configuration was used to measure the retention of the
test compound in the scrubber and to determine the instrument response with the potential interferant
present. Since many of the absorbance readings were low, the source hags were attached directly to the
monitors to obtain adequate instrumental sensitivity.
RESULTS AND DISCUSSION
In the first phase of the study, experiments were conducted with the glass manifold system to
determine whether systematic differences exist between the U V and the ehemiluminescence monitors when
ozone is measured in humid zero air. Initial checks were conducted to determine if a water vapor
interference was present in the absence of ozone; no clear water vapor interference for either approach
could be detected. Experiments using both types of monitors were then performed at known relative
humidities for ozone concentrations of 85, 125, and 313 ppbv to see if an interference could be detected
under these conditions, and if an interference existed, to determine the direction and magnitude of the
interference. An independent ozone determination indicated that the UV monitors high reliable under
these conditions However, a positive deviation of 3.0% for each 1 % (or 10,000 ppmv) of water in the
sample was found for ehemiluminescence instruments at dew point temperatures ranging between 11 and
23 °C. These experiments cover the range of dew points frequently seen in urban atmospheres.
Moreover, the interference was found to be independent of the absolute ozone concentration. The result
is similar to the results of several prior published and unpublished studies':-4. However, in previous
studies, no attempt was made to accurately quantify' the magnitude of the interference.
The purpose of another part of the study was to determine whether condensed water in the
instrument sampling lines could give rise to noisy conditions in which the UV instruments give
systematically higher ozone values than the ehemiluminescence instruments'. The outputs from the
instrument* were monitored on strip-chart recorders over periods of 5 hours for each experiment. Three
experiments were performed under these conditions at nominal ozone concentrations of 330 ppbv, 325
ppbv, 125 ppbv. Figure 3 shows the chart recorder traces for each of the three instruments at a nominal
ozone concentration of 325 ppbv and tor a manifold RH of 85% at a temperature of 32.1 °C. During this
experiment, the ambient laboratory temperature was 24.6 "C, and the dew point temperature of the
mixture emanating from the manifold was on average 5 °C higher than the laboratory temperature. Chart
408
-------
traces for other experiments in this series were similar in character to those of Figure 3.
As seen in Figure 3(B) and (C), the UV monitors appear to be noisier than usual. Moreover,
Figure 3(C) indicates that the Teco UV monitor gave a periodic negative spike followed by a positive
spike. These spikes appeared to have been synchronized with the air conditioning cycle, which strongly
influenced the RH in die manifold, as the bottom panel indicates. Condensed water was present in the
sampling lines during the times these spikes were observed. For the instruments tested, (he increase in
the noise at these high humidities appeared to be related more to a specific instrument, rather than a
specific model type. It should be noted that overall the condensed water did not cause the integrated U V
instrument readings to be higher than the chemiluminescence readings. Similar to previous
measurements, the chemiluminescence instruments showed a higher average reading, but there was no
observed increase in instrument noise. These results are relevant for cases in which the outdoor dew
point is higher that the temperature of the monitoring station.
Two other measurement problems specific to the scrubber canisters used in UV monitors have
also been reported. One problem involves breakthrough of ozone by the scrubber leading to a negative
interference and the second involves retention of absorbing compounds (e.g., aromarics) on the scrubber
leading to a positive interference. For correct operation of the U V monitor, the scrubber must remove
100% of the ozone, while retaining no compounds that absorb at radiation at 254 nm. Anomalous
scrubbers from field monitors were tested for ozone breakthrough at approximately 200 ppbv ozone for
various NO: concentrations (see above) and humidity levels. As seen in Table 1, there were several
failures of these anomalous scnibbers to remove 100% of the ozone but the failures only occurred under
humid conditions. Figure 5 shows the chart trace tor a failing scrubber. In this case, when the air
sample was dry which is normal during instrument calibration and span checks, the scrubber was found
to remove ozone completely. Once water was added, ozone began to breakthrough the scrubber. In (his
particular test, the maximum loss of scrubbing efficiency was 40%. Under field conditions at the same
relative humidity, this would result in an ozone reading that was 40% low if liiis scrubber were installed
in a field unit. After the relative humidity of the sample was adjusted to 89%. the ozone breakthrough
increased momentarily and then the scrubber returned to normal operation.
The chart trace in Figure 5 shows failure of the scrubber to remove 100% of the ozone under all
conditions but, perhaps more importantly, the apparent transient nature of the problem. Since only
previously deployed scnibbers showed evidence of humidity-assisted ozone breakthrough, new scrubbers
were exposed to an irradiated synthetic urban air mix to find conditions under which they might fail.
Four different types of canisters (Dasihi "gold", Dasibi "blue", Monitor Labs and Advanced Pollution
Instruments) were exposed continuously for 13 weeks to the effluent from the smog chamber. Periodic
tests of the scrubbers found no evidence of failure induced by synthetic smog mixtures. Therefore, the
exact conditions which brought about the ozone breakthrough problems of the field units are unknown
at the present time.
Experiments were also performed to rest the degree to which the ozone scrubbers could retain
compounds which absorb radiation at 254 nm. In an initial study,2 measurements of ozone were made
with a UV monitor from a mixture comprised of photochemically-derived products including ozone
produced during irradiations of toluene/NOx mixtures. The effluent from the irradiation was sent through
two different scrubber cans as seen in Figure 4. Benzaldehyde and other aromatic ring-retaining
photooxidation products (o-cresol, nitrotoluene, etc.) were almost completely removed from the sample
by the ozone scrubbers.
However, in additional tests, it was found that products which deposit in the scrubber can be
409
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reversibly emitted from the MnO;-coated screens when the humidity of the sample subsequently increases.
In one test, two scrubbers were exposed for 20 minutes to a source bag of 2-nitrotoluene and then placed
in the sample inlet line of a UV monitor. With a dry stream of clean air passing through the
contaminated scrubbers there was a slightly elevated signal (Figure 6). When the humidity of the
manifold sample increased to approximately 50%, the 2-nitrotoluene was flushed from the screen surfaces
to a level that could be read on the UV monitor. Thus, depending on the timing of absorption and
emission, the scrubber can produce either a positive or a negative measurement error when aromatic
species are present in the sample.
Comprehensive studies of the effect of aromatic compounds on the UV measurement technique
are sparse6. In this study, individual aromatic compounds were tested to determine the magnitude of an
interference. To be an interference for the UV monitor, a compound must both absorb at 254 nm and
be retained by the scrubber system. Results from this study tor the compounds tested to date are given
in Table 2. This list does not cover the entire range of compounds which have been found to absorb
radiation at 254 nm, and additional compounds such as mercury, PAHs and nitrocresols need to be tested.
It is important to note that some chemicals give a greater response than ozone on a molar basis.
Aromatic compounds present in the highest concentrations in ambient air (e.g., toluene) had relatively
little effect on the UV monitor since they are weak absorbers and essentially pass through the scrubber.
There may be numerous aromatic products (e.g. 2-nitrotoluene) present in low concentrations in ambient
air (1-10O pptv) which absorb at 254 nm and are retained. If completely retained, a single product with
a molecular weight of 150 g/mol can deposit 25 ng of material on the surface of a scrubber in one month
at 100 pptv levels in the field. Normally UV monitors operate lor several months without scrubber
replacement. It is possible that one or more of th&se aromatic compounds can cause the anomalous
behavior seen in suspect field scrubbers. Presently, it is impossible to speculate on the exact compounds
or mechanisms which cause scrubber failure without ambient measurements of potential interfering
compounds,
CONCLUSIONS
While this study has not been completed, it is possible to draw some preliminary conclusions from
the data presented above. Both the chemiluminescence and UV ozone monitors are subject to
measurement errors. The chemiluminescence monitor, which is based on the specific reaction between
ozone and ethylene, appears to have a positive deviation with humidity. Calibration of this type of
monitor at a representative humidity can minimize the error caused by water vapor in the sample. The
UV technique has several different measurement interferences requiring further study. During limes
when the monitoring station is at a temperature below the dew point of the incoming sample, instrument
noise increases significantly. The magnitude of the noise is instrument- rather than manufacturer-specific.
The scrubbers used in the reference side of these instruments can cause both positive and negative
measurement errors. Ozone breakthrough is a transient problem which can occur under humid
conditions. Testing UV monitors in the field with a humidified ozone source is one method to detect
anomalous ozone scrubbing efficiency. The interaction of aromatic compounds and the surfaces of the
scrubber can cause positive measurement errors when the materials are retained and negative errors when
the materials subsequently elute from the scrubber surface.
ACKNOWLEDGMENTS
Suspect scrubbers and reports on measurement anomalies were provided by Larry Ellibot (St.
Louis Co. MO). Elton Erp (State of Virginia), A1 Leston (State of Connecticut), and Charles Bellot (State
of Louisiana). Valuable discussions were held with J.J. Bufalini, K.A. Rehme and C.F. Smith of the
U.S. EPA. This work was supported by the I'.S EPA and the American Petroleum Institute.
-------
REFERENCES
1. A. Leston, W.M. Ollison. Estimated accuracy of ozone design values: are they compromised by
method interferences? Troposnheric Ozone: Nonattainment and Design Value Issues, p. 451, Air
and Waste Management Association, Pittsburgh, PA. October 27-30, 1992.
2. T.E. Kleindienst, E.E. Hudgens, D.K Smith, F.F. McEIroy, and J.J. BufaJini. Comparison of
chemiluminescence and ultraviolet ozone monitor responses in the presence of humidity and
photochemical pollutants. J. Air Waste Vfanape. Assoc.. 43:213-222 (1993).
3. T.E. Kleindienst, D.F. Smith, E E. Hudgens, L.D. Claxton, J.J. Bufalini, and L.T. Cupitt.
Generation of mutagenic transformation products during the irradiation of simulated urban
atmospheres. Environ. Sci. Technol.. 26:320 329 (1992).
4. 1992 Annual Book of ASTM Standards. P.C. Fazio et al.. Eds. D 5149-90 Standard test method
for ozone in the atmosphere: continuous measurement by ethylene chemiluminescence. Vol. 11.03
ASTM, Philadelphia, PA, October, 1992, p.475.
5. C.P. Meyer, C.M. Elsworth, I.E. Galbally. Water vapor interference in the measurement of
ozone in ambient air by ultraviolet absorption. Rev. Sci. Instr.. 62:223 (1991).
6. D. Grosjean and J. Harrison. Response of chemiluminescence NO„ analyzers and ultraviolet
ozone analyzers to organic air pollutants. Environ. Sci. Technol.. 19:862-865 (1985).
411
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Table I. Summary of experiments to test the effect of NOj concentrations on the performance of suspect
scrubbers in the presence of various levels of relative humidity. For each entry, the values represent,
respectively, the number of scrubbers tested, the number failed, and Hie number of hours of exposure at
an ozone concentration of 200 ppbv.
[NOJ,
ppbv 0% 25% 50% 75% 95%
0
3,
©
O
1, 1, 2
1, 0, 5
1, 1, 2
1, 1*. 2
50
3,
0,7
3, 0,6
4, 2, 19
4, 3, 20
4, 0, 16
100
1, 0, 5
4, 2, 17
2, 0, 19
2, 0, 16
2, 0, 20
200
1,
0, 6
1, 0, 19
1, 0, 15
-
1,0, 6
Table II. Measured absorbances at 254 nm in UV cell for selected aromatic compounds.
Compound
Absorbance
(L/mol-cm)
% Retained
by Scrubber
Signal (%)
Ozone
3200
100
100
Benzene
93.3
0
0
Toluene
137
0
0
p-Xylene
140-200
0
0
Benzaldehyde
230
<10
<1
Styrene
3600
100
113
2,5-Dimethylstyrene
4710
100
147
o-Cresol
599
98
18.7
2-Nitrotoluene
2590
97
78.4
412
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Teflon Source
Flew Controller
Zero Air
Dump
Pump
Ozone Generator L.J^.
Heat Tape
Ref Hum and
' Temp Monitor
Glass Manifold
Variac
Test Scrubber
Standard Dasibi
Bendix #1
ML9811
Pa032
Figure 1. Experimental apparatus for measuring ozone interferences.
sample in , j filter
sample in , filter
clean air
T K
Q-to cell
'valve
¦2Z7ZZZ77ZZZ~TZZZ77"Z]
Bypass Configuration
•' /' /. / / / // /
to cell
, x valve V
scrubber can $
V
\
rr7T7^j../j
j
Normal Configuration
Figure 2. Schematic for measuring 254 nra absorbance and retention of test compounds.
4B
-------
8 . I!'
; -8
'nrrrT
Helativ^
Uumdty
RoomjTernp
anifoHtTemp
ManlfckJ RH
24 .6 C
32 1 ft
Jew"-1 -J29.2 CI
Figure i. The effect of condensed water on ozone monitors.
Dasib; Scrubber
T®co Scrutabof
S>
us
o
L. iL,
t il l
ToKione Products
(Unr»ctubbed)
Ring-Rotaining Proaucts
ULi L j_ii J^u—J<1 ¦ Jul iw^
10 15 20
Roten'jyn lime (min)
V S
25 *
Figure 4. Retention of toluene photooxidation products on
scrubber cans. Products generated from a toluene/NOx
irradiation.
-------
RH<4%
RH=89%
RH=6B%
RH=48%
RH<4%
20<
>0
T
imp:
¦27 "
-
—LSI
Is.1
3
1
0
,1
[C
3
zone
0
]/10,
4
ppb\
0
5
D
6
0
7
t
Ji
bo.
ofcU
.r
i ac
1
pfl
ink
rslef
I7C
1
S> b
*bb'
tx-
irt 2
t
- D
1
i
t
t>ru
7.Mrr\
|
i
Figure 5. Chart trace showing ozone breakthrough from suspect scrubber can. (Vertical scale: Time;
Horizontal scale: Ozone Concentration, 7(X) ppbv full scale)
2,500
2,000
©
w
c
8.1-50Q
CO
0>
CC
15 i,ooo
'«
ro
D
500 -
Temp.= 31.7 C
blue can gold can
After 20 min exposure with
1.4 ppmv 2-nitrotoluene
i Ti
RH<4%
RH=52%
**>>>,
20
40 60 80
Reading Number
Figure 6. Instrument response from scrubber contaminated with 2-nitrotoluene. (See text for details;
readings taken every 25 seconds.)
-------
Real Time Electrochemical Measurement of Ozone in the
Presence of Nitrogen Oxides
William R. Penrose and Li Pan
Transducer Research, Inc.
Nupcrville, IL 60540
Will M. Ollisan
American I'ciroleum Institute
Washington, DC 20005
Current regulatory models (lJSEPA/pNEM-03) estimate population ozone
exposures within multiple microenvironments averaged over clock hour time periods.
Validation of model algorithms requires measurement of personal ozone exposures of
free-ranging individuals over hourly lime frames within changing mictocnviionmental
air quality. Ozone can be measured with electrochemical sensots at sensitivity limits of
5 ppb if the sensor is periodically corrected for baseline drift, 'l'he electrochemical
sensor responds comparably to 03, NO,, and MONO. Initial attempts to measure ozone
passively in the presence of nitrogen oxides by periodic ozone-scrubbed baseline drift
corrections were unsuccessful due to the rapid changes in NO, levels within scveial
microenvironments. We have constructed a prototype active, battery-powered,
data-logging personal monitor using two sensors in tandem with an ozone removal
filter in between. The difference in the sensor signals is due to ozone; thus, corrections
for NOx interferences are made on-line in real time without sacrifice of sensitivity.
416
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The Development of an Active Personal Ozone Sampler
Using a Diffusion Dcnuder
AS. Geyh, J.M. W'olfson. and P. Koutrakis
Harvard University
School of Public Health
665 Huntington Avenue
Boston, Massachusetts 02115
J. Mulik
U.S. EPA
Research Triangle Park, I*JC 27711
Personal, microcnvirunracntal and indoor ozone monitoring is currently
carried out using a passive sampling device which is both light-weight and
inexpensive. However, the collection properties of these samplers have been
found to be sensitive to wind effects and sampler placement, thus limiting their
potential use for personal monitoring. In addition, because of their relative
insensitivity, these samplers cannot used for short-term monitoring of ozone at low
concentrations. In response to these problems we are developing a light-weight active
ozone sampler which uses a single tube diffusion denuder for sample collection.
The new single tube diffusion dcnuder (STTD) consists of a 1.4 cm (ID) x 10
cm etched I'yrcx tube attached to a very small, low-flow, relatively low-cost personal
pump. Tube diameter and length were chosen to maximize collection efficiency at a
sampling rate of 65 mL/min. The tube is coated with a nitrite reagent which has been
successfully used in the passive ozone samplers.
Variations in relative humidity, ozone concentration, and total ozone
exposure have relatively small affects on the accuracy and precision of the STTD. In
addition, the low limit of detection (LOD) of approximately 20 ppb-hrs gives a tenfold
increase in sensitivity over the passive samplers for which a 200 ppb hr LOD has beeu
determined. This new active sampler thus makes possible both short-term personal and
microcnvironmental monitoring.
417
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Evaluation of Passive Samplers for Field Measurements
of Ambient Ozone in the National Parks
John D. Ray and Miguel Flores
Air Quality Division
National Park Service
Denver, CO 80225-0287
ABSTRACT
In 1993 a follow-up study was conducted to the 1991 trials by the National Park Service of passive
samplers for integrated measurement of ozone A preliminary factorial design study was used to verify
consistency between samplers and between analysis laboratories. It was found the significant differences in
measured ozone were being introduced by the polypropylene rain shields that were used in the 1991 trials.
l'VC plastic rainshields were used subsequently.
For the main part of the 1993 study, five sites in two difl'erent national parks were used to compare
passive sampler ozone measurements to average hourly exposures determined with UV-photoinetric ozone
analyzers Passive sampler measurements agreed well for each site and were within ±10% accuracy for
each measurement period. The overall collection factor varied somewhat by site (21.565 ±1.59 cnrVmin),
had good repeatability at each site, but overall accuracy fo multiple sites was -20%. The passive samplers
generally met the criteria established prior to the study and appear to be suitable for field use to measure
ambient 07one when used as part of a well designed ozone measurement program.
INTRODUCTION
Ambient air quality monitoring in remote locations such as national parks and wilderness areas
using conventional instrumentation is hampered severely by the general lack of commercial AC. power in
these areas. Information on air quality levels in these areas is often necessary to address resource
management issues related to the effects of air pollution on the natural resources of such areas.
Interest, in personal exposure monitoring over recent years has resulted in the development of
passive sampling devices that contain no moving parts and rely simply on the principle of gas diffusion.
Although passive devices were designed initially to sample over durations of a few hours, they are now
being tested over durations of a few weeks for use in ecological monitoring programs'.
In 1991 a study was conducted by the National Park Service to evaluate the accuracy of the Ogawa
passive ozone samplers during sampling durations of one week or longer under a variety of environmental
and meteorological conditions. The passive samplers were deployed at eight NPS ozone monitoring
locations with different average relative humidity, elevations, and ozone mixing ratios. Other variables,
such as, temperature, winds, solar radiation, and site environment were also measured.
The conclusions of the 1991 study were that the accuracy exceeded J.20% , that larger numbers of
replicates were needed, and that differences in collection rates between parks were unacceptably large A
linear relationsliip between passive and continuous o/.one measurements was obtained with an R2 of 0.40.
418
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Short exposures (1 week) of the passive samplers worked better than extended (4-12 weeks) exposures.
In light of those results, a second, more limited study with specific objectives was proposed
A number of other field trials of the passive ozone samplers have been reported,1"1 however,
several of these have not appeared in the peer review literature as yet. Prior reports on field use of the
passive samplers have indicated an accuracy of-20%, which is far from what is expected from a
continuous ozone monitor. However, for areas where no ozone measurements are available, even the
±20% would be an improvement in the understanding of local ozone exposures.
EXPERIMENTAL
The 1993 study consisted of a preliminary experiment designed to resolve experimental problems
that were noted in the 1991 trials and a main experiment designed to test accuracy, precision, and number
of replicate samplers required. Multiple sites were chosen to test the variability of the passive samplers
under field conditions
The Ogawa passive samplers consist of a double-sided filter holder that is mounted on a "badge"
with a clip on the back. Inside the filter holder are two nitrite coated filters. When the nitrite coated filters
are exposed to the air, ozone diffuses through the end-cans and reacts with the nitrite to form nitrate. To
protect the samplers from direct contact with water, a rains'nield was made from 7.6 cm diameter PVC
drain pipe, a PVC end-cap, and Teflon tubing for supports. The samplers are mounted so they are 1.3 cm
about the open end of the rainshield
A preliminary experiment was designed to study some of the variables that could effect passive
samplers. A 23 factorial design was used to examine the effects of analysis by different labs, type of rain
shield, and relative placement of the samplers within the rain shields. Eight combinations of the three
factors were studied at a contractor's facility. Analyses of the coated filters were performed in laboratories
at the Harvard School of Public Health and at Research Triangle Institute (RTI). Thus, 10 samples went to
each lab from this preliminary study.
The main study plan was conducted in August at three sites within Great Smoky Mountains NP
and at two sites within Sequoia-Kings Canyon NP. At each site there was a continuous ozone monitor for
local calibration of the passive samplers and enough replicates were used to ensure that differences of 5
ppb ozone would be statistically significant between sites Each exposure consisted of 5 passive samplers
and 2-4 blanks. This allowed for subtraction of the blank for each set of samples and an estimate of the
limit of detection for the method. Analysis were based on composites of coated filters from the two sides
of each Ogawa device. All samplers had the same coating levels of nitrite and used the same extraction
volumes in the analysis. The passive sampler badges were mounted inside PVC rainshields and the
rainshields hung from PVC supports attached either to the monitoring site shelter or tower. Each passive
sampler was located at the same height as the continuous ozone monitor intake and within five feet of the
intake.
The sites differed by elevation and vegetation, both of which were expected to affect ozone levels
and local winds Although the projected ozone concentrations at the two parks were expected to be
similar, the organic precursors for the formation of the ozone were expected to differ. Sequoia-Kings
Canyon NP would generally be expected to have larger anthropogenic concentrations of volatile organic
compounds (VOC) and Great Smoky Mountains NP to have larger biogenic concentrations of VOC. This
difference challenges the passive samples more than if adjacent parks were used for comparison
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RESULTS AND DISCUSSION
Results from the preliminary study aided in the planning of the main study A significant finding
was that the polypropylene rainshield used in the 1991 study led to ozone values 30% high. The PVC
rainshield gave results comparable to published reports" and had greater reliability. The other factors of
badge location and analysis lab were found to contribute less than 2% error.
The unexposed passive samplers, here referred to as blanks, provided the baseline amount of nitrate
oil the filter pads. In the 1991 study the average one-week exposure blank was 1S6 ppb-hrs whereas in the
1993 study the average blank was 538 ppb-hrs. In general the blank analysis at RTi was consistent for the
different weeks and about one-half the nitrate observed by the Harvard lab The higher blanks obtained by
the Harvard lab may be because they were analyzed a few weeks later or may indicate some analytical bias.
The limit of detection (LOD), taken as three times the standard deviation of the blanks, was calculated as
1.5 ppb average ozone exposure over one week.
Reproducibility for the passive samplers was determined from the replicates. To remove the
influence of different ozone levels, the relative standard deviation (RSD) was calculated as the percent
where the standard deviation was divided by the average ozone mixing ratio. For the 1993 study, the RSD
for the duplicates was 1.0% for Great Smoky Mountains NP (Tabic I) compared to the 5.0% in the 1991
study. At Sequoia-Kings Canyon NP, the present RSD was less than one-fifth of the value in the 1991
study. The lower variability was most likely due to use of the PVC rainshields, to use of a larger number
of replicates over a shorter exposure time, and to improvements in the handling and analysis of the
samples. An estimate for the precision (as the 95% confidence interval) of the passive was ^1.0 ppb. This
was better than expected from the results in the previous study.
Since each field site had a continuous ozone analyzer collocated with the passive samplers, a
collection factor was calculated for each site by sampling period. In principle the collection factor should
not change either with week being sampled or the sample location. In practice the results indicate a shift in
the collection factor from an as-yet-to-be-identified interference. Table II shows the changes in the
collection factors by site during the study and Table III summaries the collection factors by week and park.
Although the collection factors at Great Smoky Mountains NP suggests an elevation pattern (i.e.,
increasing collection factor with increasing elevation), the relationship docs not hold for the samplers at
Sequoia It is likely that some influence other than atmospheric pressure is involved.
The best results were obtained when the average collection factor for multiple sites in one park
were used for the samplers in that park. An overall collection factor of 21.565 -H. 59 cm3/min (95%
confidence limits) was used to compute the ozone exposures in the different parks. The 95% confidence
limits for the collection factor were J.7.4% compared to ±12 1% for the 1991 study.
Direct comparison between the passive sampler and the continuous analyzer ozone concentrations
are presented in Figure 1 for all of the sites and exposure periods. The linear regression line in Figure 1 is
given as equation (1):
Passive 03 0.963 x (Continuous Ozone) R" 0.91 (1)
This data set was not well suited for determining the response linearity of the passive samplers. However,
as can be seen from Figure 1, all of the data falls within the J.20% values
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CONCLUSION
The results of this study indicate that the Ogawa passive ozone samplers can be used to measure
ozone with an accuracy of better than ±20% and with enough precision to distinguish to better than 5 ppb
between two sites within a park. 'Hie reproducibility of measurements is such that only 2 samplers need to
be used at each measurement site to achieve this level of precision Within these boundaries, the passive
samplers appear to be suitable for low-cost spatial and temporal ozone measurements within a given park
where there is a continuous ozone monitor to act as a reference.
With slightly less accuracy, the passive samplers can be used at widely separated parks when a
common collection factor is used for the calculation of the ozone exposures. It is recommended that either
a temporary continuous ozone monitor should be collocated with one of the sampling sites or the nearest
existing ozone monitor should be used with collocated passive sampling as a check on the collection factor.
The passive samplers can be used as screening devices for those locations where no prior ozone monitoring
has taken place.
REFERENCES
1. Mulik, J D., J L. Yarns, P. Koutrakis, M Wolfson, D. Williams, W. Ellenson, and K Kroraniller, "The
Passive Sampling Device as A Simple Tool for Assessing Eicological Change," in Proceedings of the
1991 U.S. LPAA&WMA international Symposium on "Measurement of Toxic and Related Air
Pollutants", VIP-21; .Air & Waste Management Association: Pittsburgh, 1991, pp 285-290.
2. Koutrakis, P., J. Wolfson, A Bunyaviroch, S. Froehlich, K Hirano, and J. Mulik, "Measurement of
Ambient Ozone Using a Nitrite-coated Filler," Anal. Chem.. 65, 209-214 (1993).
3. Mulik, J. D., EPA, AREAL, "Study Shows Passive Sampling Devices Cost-effective Alternatives for
Remote Monitoring," FJ'A AMTIC News, Vol. 3, No. 3, p. 2. 1993
4 Helming, M , EPA, Region VIII, "An Ozone Saturation Study Along the Utah Wasatch Front," EPA
AAfTlCNews. Vol. 3, No. 3, p. 6, 1993
5 Schweiss, I, HP A Region X, "Method Development Study for an Inexpensive Portable Ozone
Sampler," EPA AMTICNews, Vol. 3, No. 3, p. 6, 1993.
421
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Table I. Comparison of Passive Sampler Precision by Week and Site (ppb Ozone).
National
Individual
- First Week -
Second Week
Park
Sites
Std. Dev. Average
RSD
Std. Dev.
Average RSD
Ozone
Ozone
Great Smokv Mt.
Uplands
0.4
22.9
1.8%
0.7
23.5 3.1%
Great Smokv Mt
I ,ook Rock
0.8
58.0
1.3%
1.0
56 5 1.7%
Great Smoky Mt
Cove Mt.
2.4
61.3
3.8%
0 8
58.2 1.4%
Sequoia-Kings Canyon
Lower Kawcah
__
—
..
06
74.0 0.8%
Sequoia-Kings Canyon
Grant Grove
-
-
-
04
67 3 0.6%
Table IL Calculated Collection Factors for Passive Samplers by Location (em'/min).
Site
Week 1
Week 2
National
Individual
Elevation
Calculated
Calculated
Average
Std. Dev.
Park
Sites
(ft)
Col. Factor Col. Factor
Col. Factor
Great Smokv Mt.
Uplands
2,000
19.07
18.75
18.91
0.16
Great Smoky Mt
Look Rock
2,700
20.98
24.29
22.63
1.66
Great Smokv Mt.
Cove Mt
4,100
24.12
26 86
25 49
1.37
Sequoia-Kings Canyon Lower Kaweah
6,200
-
19.43
19.43
-
Sequoia-Kings Canyon Grant Grove
6,600
--
20.82
20.82
—
Table in. Summary of Collection Factors by Week for Each Park (cnrVmin).
Week I
Week 2 Week 2
Great Smoky
Mountains
Great Smoky Sequoia -Kings
Mountains Canyon
Average
21.39
23.30 20.13
Std. Dev.
2.08
3.39 0 70
Range
5.05
8.12 1.39
422
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Development of a New Semi-Volatile Organic Compound Sampler
C. Stomas and P. Koitlrakis
Harvard University
School of Public Health
IJoslon, MA 02115
R.M. Burton
U.S. EPA
Research Triangle Park, NC 27711
A new sampler has been developed lo sample scmi-volalile organic compounds.
The sampler utilizes the principle of virtual impactor to efficiently separate the
particulate from the gas phases of organic compounds. The virtual impactor consists of
a slit-shaped nozzle where the aerosol is accelerated, and another slit-shaped nozzle
that collects the particulate phase of organics (plus a small and known fraction of the
gas phase). The acceleration slit is 0.023 cm wide, the collection slit is 0.035 cm wide,
and both slits arc 11 cm long.
The virtual impactor's 50% cutpoint has been determined experimentally to be
0.12 um. In addition, interslage losses have been determined (in all configurations
tested, particle losses ranged from 5-15%). The impactor's sampling How rate is 284
liters/minute, with a corresponding pressure drop of 100 inches H,0. Higher or lower
sampling flow rates can be achieved by increasing or decreasing the length of the slits.
Tests for volatilization losses have been conducted by generating organic aerosols of
known volatility, and comparing the impactor's collection to that of a filter pack
sampling in parallel. The experiments demonstrated negligible volatilization losses
(<5%) for the compounds tried.
Particles are collected on a filter connected to the minor flow of the impactor,
followed by a sorbent bed to collect material that volatilized from the particles. The
organic gas phases is collected on a sorbent bed, connected lo (he major flow of the
impactor.
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Outdoor Air NO, Speeiation by a Selective Denuder Collection System
Robert S. Draman and M. Stacey Thomson
Department of Chemistry
University of South Florida
Tampa, FL 33620
A series of interior coated hollow tubes has been studied for ihe collection
and analysis of ambient air for gas phase nitric acid, nitrous acid, nitrogen dioxide,
nilrosamines. and nitric oxide. The tube surface sequence consists of, in order, tungsiic
oxide, potassium-iron oxide, copper iodide, carbon, and cobalt oxides. Collected
analytes are removed by heating the collection tubes with chemiluminescent detection
Tor the analysis. Detection limits are in the fractional nanogram per sample range.
Prior work has verified high collection efficiency and specificity of the sequential
collection.
Results of the surface analysis of the coatings will be presented. Current work
includes a study of interferences and application of the method. Possible interferences
from carbon dioxide, carbon monoxide, ozone, formaldehyde, nitrous oxide were
studied. Temperature and humidity effects were also studied. The analysis system has
been applied to analysis of outside air in a producing orange grove area at which some
impact from nitrogen oxides was suspected to have a serious impact. A contiast o£
indoor versus outdoor air will also be presented.
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FIELD EVALUATION OF A GLASS HONEYCOMB DENUDER/F1LTER PACK
SYSTEM TO COLLECT ATMOSPHERIC GASES AND PARTICLES
Constantinos Sioutas, Petros Koutrakis, J. Mikhail Wolfson, and Lenorc S. Azaroff
Harvard University
School of Public Health
665 Huntington Avenue
Boston, MA 02115
James D. Mulik
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
ABSTRACT
We have developed a glass honeycomb denudcr,/filter pack system to sample atmospheric
inorganic gases and particles. The main feature of the sampler is the denuder component,
which has a large number of small hexagonal glass tubes sealed inside an outer glass tube.
Outdoor concentrations of nitric acid (HNO,), nitrous acid (HONO), ammonia (NH,), sulfur
dioxide (SO;), and fine-particlc sulfate(SO/') and ammonium (NH4+) determined with the
honeycomb denuder sampler were compared to those determined with a collocated
Harvard/EPA Annular Denuder System (HEADS). The average collection of the HEADS
sampler was higher than that of the honeycomb sampler for NII3 and UNO,, whereas
concentrations of SO,, HONO, and particulate NH/ and SO,2 determined by both samplers
were in excellent agreement.
INTRODUCTION
Tubular diffusion denuders have been used in several atmospheric studies to collect
gaseous and particulate atmospheric pollutants (Fcrm, 1979; Shaw et a!., 1982: Forest et a!.,
1982; Braman et al., 1982). Possanzini et a). (1983) designed and characterized an annular
denuder system that collects reactive atmospheric gases more efficiently, per unit length, than
the tubular configurations. Koutrakis et al. (1988) designed and evaluated a glass
impactor/annular denuder/filter pack system (HEADS) operating at 10 LPM. Measurements of
SG2, HN03, and IIN02 gases showed mean collection efficiencies of 0.993, 0.984, and 0.952,
respectively. The gas collection of the denuders and the fine particle mass and sulfate
concentrations on the filter pack of this system was compared to an EPA sampler developed by
Vosslcr et al. (1988) by conducting collocated studies. The gas and particle concentrations
obtained from both the EPA and the HEADS samplers were in excellent agreement.
We have developed an alternative system which maintains and improves operational
features, while being more compact (Koutrakis et al., 1993). The main, novel feature of the
proposed system is the denuder component, (Figure 1), which is a cylinder with a height of 3.8
cm and a diameter of 4.7 cin, containing 212 hexagonal glass honeycomb lubes, with an inside
diameter of 0.2 cm. The tubes are scaled inside an outer glass tube. The collection efficiency
of the honeycomb denuder was compared to those, of the annular denuder for HNO, and NH,
for experiments simulating atmospheric conditions and were found identical. In addition, inlet
losses of reactive gases in both systems were found to be insignificant. The capacity of the
honeycomb denuders tinder simulated atmospheric conditions was found significantly higher
than then capacity of annular denuders for tests using HNO, and NHj. Furthermore,
laboratory and field experiments indicated that fine particle losses (dp<2.5 nm) were less than
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5% (Sioutas ct al., 1994).
In this study we conduct a field evaluation of the new honeycomb denuder/filter pack
sampler by comparing its performance with the performance of the previously developed
HEADS system (KouIrakis et a!., 1988). The concentrations of nitric acid (HNO,), nitrous acid
(HONO), ammonia (NH,). sulfur dioxide (S02), and fine-particle sulfatcfSO/") and ammonium
(Ni l/) determined witli the honeycomb denuder sampler are compared to those determined
with the collocated Harvard/EPA Annular Denuder System (HEADS).
METHODS
Design and description of samplers
The sampling flow rates in both the HEADS and the honeycomb denuder samplers are
10 LPM. A detailed description of the HEADS sampler is given in a paper by Koutrakis et al.
(1988). Also, a detailed description of the honeycomb sampler can be found in a study by
Koutrakis et al. (1993). Briefly, the MEADS system consists of a borosilirate glass impactor,
two glass annular denuders, and a FEP Teflon filter pack. The impactor has been calibrated,
and at a flow rate of 10 LPM its 50% cutpoint is 2.1 jim (Koutrakis et al., 1990). The design of
the annular denuders is similar ro that of Vossler et al. (1988). The denuder length is 26.5 cm,
the outer diameter of the inner cylinder is 2.20 cm, and the thickness of the annulus is 0.10 cm.
The first denuder is coated with Na.CO}/glycerol to collect SO,, HNO,, and HNO,. The
second denuder is coated with 2% citric acid:l% glycerol in a watenmethanol solution to
collect ammonia. Following the second denuder is a PTFE Teflon filter pack containing a
Teflon filter to collect fine particles for fine particle mass, sulfate, and nitrate concentration
measurements. The second filter is a 47-mm diameter glass fiber filter, coated with Na,C03 to
trap UNO,.
The honeycomb denuder/filter pack system, shown in Figure 1, has three essential
features: a) an impactor to remove coarse particles (dp>2.1 jim) from the air sample : b) two
glass honeycomb denuders; and c) a two stage filter pack to collect fine particles. The inlet
has a short ehitriator, which points downwards to help exclude the largest particles. The
circular array of nozzles causes particles larger than 2.1 jim to impact on the impactor plate, a
ring of sintered stainless steel, coated with mineral oil. A transition section allows the sample
air to flow smoothly and have uniform flow through the individual honeycomb tubes of the first
ienuder. A Teflon coating minimizes internal surfaces from interaction with reactive, gases,
file first houeycomb denuder (coated with sodium carbonate/ glycerol to collect acid gases) is
icparated by an inert spacer from the second denuder (coated with citric acid/glvcerol to collect
>asic. gases). A stainless steel spring keeps the components in place. A third denuder can be
jlaced. if desired. The two stage filter pack has a Teflon filter to collect fine particles (below
!.l |iui) and a sodium carbonate-coated glass fiber filter to collect acid gases produced from the
eaction of acidic fine particles with particulate ammonium salts of these acid gases. A third
tage can be added in the filter pack if it is needed Both the inlet and filter part components
re connected to the sampler body using spring clips.
ampling and analysis
Ambient air sampling experiments were conducted on the roof of the Harvard School of
ublic Health in downtown Boston during the summer of 1993. Two HEADS samplers with a
ow-controlled pumps operating at 10 LPM sampled simultaneously with two honeycomb
enuder/filter pack samplers, also equipped with flow-controlled pumps.
The upstream denuder in each of the. collocated samplers (annular and honeycomb) was
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coated with 1% NaX'Oy'l glycerol in a 1:1 methanol/water solution, to collect acid gases
(S02, IINOj, HONO), whereas the downstream denuder was coated with 2% citric acid/1%
glycerol in methanol, to collect ammonia. The collection efficiencies of both samplers for
HNOj, HONO, SO,, and NIlj were found to be 98% or higher (Koutrakis et a!., 1988;
KouIrakis et al., 1993). After being coated, the denuders were dried with clean dry air and
capped to protect them from acid gases After assembling the samplers, leak tests were done in
the laboratory.
Only the Teflon filler in the filter packs (a 47 mm teflon filter, Gelman Sciences) was
used in the field study, for both the Honeycomb sampler and the HEADS. The second and
third filters are. normally used to collect nitric acid and ammonia produced from the reaction of
acidic fine particles with particulate ammonium salts, as well as the dissociations of these
unstable salts. The amounts-of HNO-, and NH, oil the second and third filters of the filter
packs are used to determine the correct particulate nitrate and acidity (H+) concentrations.
The exact method for calculating these concentrations has been described elsewhere (Koutrakis
et al., 1992). For the purposes of our field study, we excluded measurements on the second
and third filters, since preliminary runs indicated that the ambient nitrate levels were lower
than the limit of detection (equal to 0.06 jig/m3). In addition, determination of acidity (H4
concentrations) was not necessary in comparing the performance of the two samplers for gas
and particulate collection.
In the end of each experimental run, the samplers were disassembled and the annular
and honeycomb denuders were extracted with 10 mL of ultrapure water. The. aqueous extracts
of the denuders were analyzed for NO,, NO, , SO/' , and NH4' by ion chromatography. The
Teflon filters were wetted with 0.15 mL of ethanol and were sonicated with 6 mL of 104 N
HC104, similar to the method described by Koutrakis et al. (1988). The extracts of the Teflon
filters were analyzed for S042" and Nil,*
Laboratory blanks were used Cor quality assurance purposes. Gaseous NH, and
particulate NH4+ concentrations were determined from quadratic regression equations for
ammonium ion standards, while particulate sulfate, SO,, IIN03, and HONO concentrations
were determined from linear regression equations for SO 24, NO"), and N02 standards,
respectively.
RESULTS AND DISCUSSION
The average concentrations for each pair of each type of sampler for HONO, UNO,,
SO,, NH,, and particulate sulfate and ammonium are shown in Figures 2-7, respectively. In
each of the figures, the concentrations determined using both samplers are plotted next to eacl
other. The detection limits were 0.1 ppb for HONO, 0.2 ppb for SO,, 0.3 ppb for NI13. 0.2 pp
for HN03, 0.14 ng/m' for NH,1, and 0.30 tig/ni1 for S04\ Twelve field runs were conducted.
In cases where fewer data points are reported (for example, in the case of HN'O,, or NH3), th<
omitted data corresponded to concentrations near the limit of detection. Table 1 shows the
mean and the percentage differences of the two samplers for all the gas and particulate
compounds measured. The mean percentage difference for a specific compound is defined as
(%) Difference = lOO^^HEADS.-HNYj/HEADS^/N
where HEADS, and HNY, are the concentrations determined in the i-th run by the HEADS
and the honeycomb samplers, respectively, and N is the number of runs. The mean different
is simply the average difference of the concentrations of the two samplers.
The SO: concentrations determined by the two samplers are in excellent agreement, as
suggested by the results shown in Figure 2 and Table 1. The average collection of the
Honeycomb sampler is 0.25% higher than that of the HEADS, while the average mean
428
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concentration difference between the two samplers is 0.05 ppb. The HN03 concentrations in
the two samplers, shown in Figure 3, indicate that the HEAPS collection is on the average
11.9% higher than the Honeycomb sampler. The observed HN03 concentrations were veiy low
(1-2.4 ppb) and several data points were omitted, since they were comparable to the defection
limit. Since the performance of the Honeycomb denuder has been compared to that of the
annular denuder in laboratory tests and found in excellent agreement (Koutrakis et ah, 1993),
the discrepancies are not likely be due to a decreased UNO, collection efficiency of the
Honeycomb denuder. It is quite possible, however, that some HN03 was lost in the inlet
surfaces of the Honeycomb sampler. The HNO, concentrations deleriniued by both samplers
(Figure 4) agree very well with each other. Although the observed levels were low (0.8-1.4
ppb), the average difference is 0.02 ppb, with the. Honeycomb sampler collection being slightly
higher (0.4%) The results for NH3 (Figure 5) indicate that the concentrations determined by
the Honeycomb sampler are on the average 18.4% lower to those of the HEADS, although the
actual differences are quite small (0.25 ppb). The ambient NH3 levels were quite, low (1-2.5
ppb), and small differences tend to overestimate the actual performance difference of the two
samplers. NH3 losses on the inlet surfaces of the Honeycomb sampler are also possible, due to
the large inlet surface area of the Honeycomb sampler (about 100 cm,, quite comparable to the
collection surface area of the annular denuder, about 380 cm.), and the relatively long
residence, time of the air samples (approximately 1 second compared to an air sample residence
time of 0.1 second in the annular denuder).
The results of the comparison of the particulate sulfate and ammonium concentrations
(Figures 6 and 7, respectively) demonstrate an excellent agreement between the two samplers.
The mean differences between the Honeycomb sampler and the HEAPS are. approximately 0.1
(ig/in3 for both fine particulate sulfate and ammonium, with the concentrations determined by
the Honeycomb sampler being 5.6% and 2.5% higher for NH4* and S04:, respectively. The
agreement in the particle collection between the two samplers should be expected, since
particle, loss tests conducted for annular demtders (Ye et al., 1991) and honeycomb denuders
(Sioutas et al.. 1994) indicated an overall loss on the order of a few percent (5% or less) for
both types of denuders.
CONCLUSIONS
The performance of a new sampler that we have developed to sample inorganic
particulate and gaseous pollutants has been compared to that of the HEAPS in a field study.
I"he key feature of the new sampler is the honeycomb denuder component, which has a large
number of small hexagonal glass tubes sealed inside an outer glass tube. This design allows
efficient collection of inorganic gases, such as HN02, UNO,, and Ni l,, while keeping the length
of the overall sampler short (the total length of the Honeycomb sampler is about 30 cm,
whereas the length of just one annular denuder is 26 cm).
The field comparison results indicated an excellent agreement between the Honeycomb
sampler and the HEADS in the concentrations of gaseous 11N()_, and SO_,, as well as the
concentrations of particulate sulfate and ammonium. For these compounds, the concentrations
determined by both samplers agree within 5% with each other.
The Honeycomb sampler was found to collect less gaseous NH3 and HNO,, compared to
he HEADS. The. average concentrations of NH3 and UNO, determined by the Honeycomb
iampler were on the average 18.4% and 11.9% lower, respectively, than those of the HEADS.
\lthough the actual concentration differences in both cases were very small (on the order of
1.1-0.2 ppb), the observed ambient levels of UNO, and NH, were very small, thus the percent
liffeiences may be exaggerated. Nevertheless, it is quite possible that significant inlet losses
an occur in the Honeycomb sampler, due to the combination of the relatively large inlet
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surface area and the long air sample residence time at the inlet. This is clearly an area where
the design o[ the Honeycomb sampler needs to be improved. We are currently designing and
will evaluate a new impactor/inlet, whose surface area is considerably smaller than that of the
original design.
ACKNOWIJKDGEM KNTS
We are grateful to Dr. Virgil Marple and Bernard Olson of the Particle Technology
Laboratory of the University of Minnesota for the characterization of the impactor. The
development and evaluation of the honeycomb denuder filter pack system was supported by
U.S. EPA through the cooperative agreement #CR 816740. It has been subjected to the
Agency's peer and administrative review and it has been approved for publication as an EPA
document. Mention of trade names or commercial products does not constitute endorsement
or recommendation for use. Finally, a patent application has been filed to the United States
Patent Office, serial number #07/938,854.
REFERENCES
1. Ferm, M. Method for determination of atmospheric ammonia. Atmps_ Environ, 1979,
13: 1385-1393.
2. Forest, J., Spandau, D.J.. Tanner, R.L., and Newman, L. Atmos. Environ. 1982, 16:
1473-1485.
3. Shaw, R.W., Jr.. Stevens, R.K., Bowermaster, I.W., Tesch, J.W., and Tew, E. Atmos.
Environ. 1982, 16: 845-853.
4. Possanzini M., Febo A. and Liberti A. New Design of High Performance Denuder for
the Sampling of Atmospheric Pollutants. Atmos. Environ. 1983, 17, 2605-2610.
5. Koutrakis, P., Wolfson, J.M., Slater, J.L., Brauer, M., and Spengler, J.D. Evaluation of
an annular denuder/filter pack system to collect acidic aerosols and gases. Environ. Sci. and
Technol. 1988a, 22fl2): 1463-1468.
6. Vossler, T.I,., Stevens, R.K., Paur, R.J., Baumgardner, R.E ,and Bell, J.P. Evaluation o
improved inlets and annular denuder systems to measure inorganic air pollutants. Atmos.
EnvjrojL 1988, 22, 1729-1736.
7. Koutrakis, P., Sioutas, C., Ferguson, S.T., and Wolfson, J.M. Development and
evaluation of a glass honeycomb denuder/filter pack sampler to collect atmospheric gases and
particles. Fjivirfm.^ci and Technol 1993, 22, 2497-2501.
8. Sioutas, C., Koutrakis, P., and Wolfson, J.M. Particle losses in glass honeycomb denud.
samplers. Aerosol Sci. and Technol, 1994, in j>ress,
9. Koutrakis, P., Wolfson, J.M., Brauer, M., and Spengler, J.D. Design of a glass impacto
for an annular denuder/filter pack system. Aerosol Sci. and Technol. 1990, 12: 607-613.
10. Koutrakis P., Thompson K M , Wolfson J.M., Spengler J.D., Keeler J. and Slater J.
Determination of aerosol strong acidity losses due to interactions of collected particles: results
430
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from laboratory and field studies. Atmos. Environ.. 1992, 26 A:9S7-995.
11. Yc, Y., Tsai, C., and Pui, D.Y.H. Particle transmission characteristics of an annular
denuder ambient sampling system. Aerosol Sci. and Techaol. 1991, 14, 102-111.
Table 1. Summary of the comparison between the HEADS and the Honeycomb samplers.
Chemical Species
Range A
Mean Difference u Mean Difference (%) c
so2
1.4-6.2
-0.05
-0.25
HNOj
0.9-2.4
0.11
11.90
hno2
0.8-1.4
-0.02
0.40
NIL,
0.9-2.7
0.25
18.44
Fine particle sulfate
1.05-11.81
-0.11
-5.64
Fine particle ammonium
0.54-3.78
-0.09
-2.55
A. Concentration ranges are expressed in (ppb) for the S02, HN03, HX02, and NH3, and iu
(ng'in3) for particulate sulfate and ammonium.
B. Mean difference is the value for (HEADS-I1NY). Mean differences are expressed in (ppb)
for the S02, HN03, HNOz, and NH„ and in (fig/m3) for particulate sulfate and ammonium.
C. Mean Difference (%) = 100*£((HEADSrHNYJ/HEADSJ/N, where HEADS, and HNY, are
the concentrations determined in the i-th run by the HEADS and the honeycomb samplers,
respectively, and N is the number of runs.
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|To Pump
Filter Pack
Spring
Denuder
Spacer
Denuder
Removable
Transition
Section
Impactor
Plate
Nozzles
Inlet
Air
Inlet
Honeycomb
Denuders
Impactor
Plate
Nozzle
Layout
Figure 1, Schematic of the glass honeycomb denuder/filter pack sampler.
432
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a
1 2 3 4 5 6 7
Run
9 101112
~
Honeycomb
HEADS
Figure 2. SO. concentrations measured by the Honeycomb sampler and tlie HIiADS.
.e
B 3
c
©
X
~ Honeycomb
H HEADS
Run
Figure 3. HNO., concentrations measured by the Honeycomb sampler and the HEADS.
433
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O-M-
1 2 3 4 5 6 7
Run
D Honeycomb
¦ HEADS
Figure 4.
HNO, concentrations measured by the Honeycomb sampler and the HEADS.
£
c
o
cj
c
c
E
£
~ Honeycomb
H HEADS
123456789 1011
Run
Figure 5. Nil, concentrations measured by the Honeycomb sampler and the HEADS.
434
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12
~ 10-
cs
h
8-
6i
4'
2-
0
f—1
_
jfi
si
*
•4
i.
i
£
1 2 3 4 5
6 7 8 9 1011
Run
O Honeycomb
H heads
Figure 6. Particulate sulfate concentrations measured by the Honeycomb sampler and the
HEADS.
4
E
~ Honeycomb
iU HEADS
1234567891011
Run
Figure 7.^Particulate ammonium concentrations measured by the Honeycomb .sampler and the
435
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The Use of PM10 Anion-Cation Difference as an
Index of Historical Aerosol Acidity
George IX t hurston, J. Carrie, D. He, and J.E. Gorczynski, Jr.
Nelson Institute of linvironmental Medicine
New York University Medical Center
Tuxedo, NY 10987
The composition of particles in the air may have a significant influence on the
health implications of inhaling these particles. Particulate matter less than 10 urn in
aerodynamic diameter (PM10) has been routinely sampled throughout the U.S. and
elsewhere in the world for years, but these samples are usually only weighed for total
mass and summarily stored. However, these samples can be (and sometimes are)
analyzed for their ionic composition (i.e of sulfates, SO,"; nitrates, NO;': arid
ammonium, NH4*) via ion chromatography. Furthermore, it is hypothesized that the
imbalance of these easily measured ions (i.e. anions-cations) may provide a useful
estimate of the remaining unmeasured major particulate cation: aerosol strong acidity,
U\ Conventional methods for directly measuring H* entail great care to protect the
collected acid from neutralization by ambient ammonia, basic particles, or alkaline
filter media, in order that all the H* show up via a pH determination. We have
conducted such direct IT measurements side-by-side with state-run PM10 samplers in
Albany, NY and in New York City, NY in order to test whether the PM10 ion
difference estimates concur with the directly measured IT. Despite the lack of
neutralization protection of the PM10 samples, it was found that the ion difference
method yields H* highly correlated with, and not significant different from, the directly
measured H'. It is thought that the ion difference is maintained on these samples by
the rapid neutralization of ambient HT by large basic particles coexisting on the PM10
filters, as well as by the weakly alkaline quartz filters themselves. This would preempt
the conversion of particulate acids (e.g., H,S04) to ammonium sulfates (e.g.,
[NH„]2S04) by ammonia gas, thereby maintaining the original sulfate-ammonium
imbalance associated with the ambient H\ Archived PM10 samples therefore
represent a potentially valuable resource regarding the nature of acid aerosol exposures
throughout the U.S. and elsewhere.
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Passive Samplers for Ambient Ozone, Formaldehyde and Sulfur Dioxide:
Indoor, Outdoor, and Personal Exposure Applications
Daniel Grosjean and Eric Grosjean
DGA, Inc.
4526 Telephone Road, Suite 205
Ventura, C'A 93003
Time-integrated measurements of air pollutants have many applications in the
context of regulations pertaining to indoor air quality, outdoor (ambient) monitoring,
and personal exposure assessment. For several years, the passive samplers developed
at DGA have been applied to cost-effective measurements of parts per billion levels of
ozone, formaldehyde and sulfur dioxide. Examples of applications will be described.
These include (a) formaldehyde measurements in indoor settings including museums,
public buildings and personal exposure; (b) ozone measurements indoor (museums,
cultural heritage buildings) and outdoor (Class I Wilderness areas; air quality surveys
in Europe, Canada and Latin America, long-term monitoring of ozone exposure in
forests) and (c) surveys of ambient levels of sulfur dioxide in several eastern European
countries.
4.37
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SESSION 9:
NC 03 STA TE IMPLEMENTATION PLAN,
MEASURING AND MODELING STUDY
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Overview of the North Carolina UAM Project
Brock M. Nicholson
NCDEIINR/DEM/Air Quality Section
15 N. West Street
Kalcigh, NO 27603
In 1992 North Carolina committed to perform photochemical gridded
dispersion modeling to support the nonattainmcnt state implementation plan (SIP)
process. In particular, UAM results would be used to demonstrate attainment by 1996
for the three moderate nonattainmcnt areas (Charlotte/Gastonia, Raleigh/Durham, and
GreensboroAVinston-Salem/High Point). However, all areas measured clean air quality
for ozone by 1992. The IJAM project then was directed at developing a maintenance
plan for the Charlotte/Gastonia area to support a redesignation request. This paper
details the overall scope, organization, current status, and future plans for the
North Carolina UAM project.
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The Sensitivity of Meteorological and
Emissions Uncertainties on Urban
Aiishcd Model Oionc Concentration
Results in North Carolina
Brian S. Timin
Janice Godfrey
North Carolina Department of Environment,
Health and Natural Resources
512 N. Salisbury Street
Raleigh, North Carolina 29535
ABSTRACT
This paper briefly summarizes the results of sensitivity studies conducted by the State of North
Carolina on the use of the Urban Airshed Model (UAM) with the July 6-8, 1988 ozone episode The
purpose of this study was to determine model sensitivity to changes in emissions and meteorological
inputs.
Hourly ozone concentrations from a base case run were compared with results from subsequent
runs in which one or more inputs were varied. Fifteen sensitivity runs were performed, examined,
and then ranked based on their effect on model results. It was concluded that for the July 6-8, 1988
ozone episode the UAM was most sensitive to changes in boundary' conditions, mixing heights, and
NOx emissions. The model was less sensitive to changes in initial conditions, VOC emissions and
elevated point source emissions.
The conclusions drawn from this study will serve as a guide to the correlation between model
inputs and model sensitivity. In addition, knowledge of model sensitivity will result in more careful
development of the critical inputs and provide a better understanding of how the model works.
INTRODUCTION
The Clean Air Act Amendments of 1990 require all ozone nonatiainmont areas, moderate and
above to conduct photochemical modeling as part of a State Implementation Plan (SIP) attainment
demonstration. Serious, severe, and extreme nonattainment areas are required to use the Urban
Airshed Model (UAM). Moderate nonattainment areas can use either UAM or the EKMA model
(EPA, 1991.)
In North Carolina, Raleigh-Durham, Greensboro-Winston Salem, and Charlotte were designated
moderate ozone nonattainment areas. The North Carolina Air Quality Section decided to use UAM
in preparation of a SIP attainment demonstration because UAM is the best modeling tool available
to evaluate ozone and plan for future emissions reductions.
Over the last year, the Greensboro-Winston Salem MSA and the Raleigh-Durham MSA have
been redesignated to attainment based on monitored air quality data and a maintenance
demonstration. A redesignation request has also been submitted for Charlotte; however, UAM must
be used to show maintenance of the ozone standard in Charlotte for the next 10 years. This
demonstration is required because future emissions in Charlotte are expected to increase due to
growth.
The UAM modeling domain was chosen to include all three urban areas and to be large enough
to include all sources that may effect the areas and to lessen the influence of boundary conditions.
The domain is 300 km X 450 km in size. The grid cells are 5km on a side, making the domain 60
X 90 grid cells. There are five vertical layers, varying in height with the mixing height, with 3
layers above the mixing height and 2 layers below The top of the domain is set at 2400 meters.
442
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The current modeling is being conducted with the original large domain, but attention is being
focused on the Charlotte metropolitan area. The sensitivity analyses conducted in this study were
applied to the full domain, but the maximum ozone concentration results are only applicable to a 25
X 25 grid cell area centered on downtown Charlotte. Figure I shows the North Carolina modeling
domain with a box around the Charlotte subdomain.
The July 6-8, 1988 Ozone Episode
The first UAM episode to be modeled was July 6-8, 1988 and represents the highest ozone
values ever measured in North Carolina. This ozone episode was characterized by strong transport
from the north. A strong surface high and upper level ridge to the west, and an upper level low to
the northeast created a northerly flow across the domain for the majority of the episode Surface
winds were light (1-3 m/s), but steady from the north and northeast on the 6th and 7th and veered to
the southeast on the 8th. Upper level winds were also from the north and northeast throughout the
episode with speeds ranging from 5-15 m/s in model layers 3, 4,and 5.
Temperatures were very hot during the period with highs steadily increasing from the upper
80's on the 6th to the upper 90's on the 8th. Skies were mostly clear, except for some clouds in
Charlotte on the afternoon of the 7th. There was no precipitation in the domain until thunderstorms
occurred on the evening of the 8th in Charlotte.
Ozone exceedences occurred throughout the domain on the 7th and 8th. Maximum ozone
concentrations on the 7th were generally observed in the Greensboro-Winston Salem area with a high
of 145 ppb. The highest monitored ozone on the 8th occurred in Charlotte with a reading of 169
ppb. Table 1 shows the maximum ozone values monitored in the three metropolitan areas.
Model Inputs to Base Case
There arc 13 UAM input files which are roughly divided into 4 categories; emissions,
meteorology, boundary conditions, and control files. A very brief explanation of input file
development follows.
The emissions were processed using the EPA Emissions Preprocessing System (EPS 2.0).
Mobile source emissions were calculated using MOBILE 5A. Area source emissions were calculated
using EPA emission factors Point source data was collected from the state regional air quality
offices. Day specific emissions data were obtained from the electric utilities (Duke Power and
CP&L) to estimate power plant emissions. Biogenic emissions were calculated using the UAM BEIS
model.
Mixing heights were prepared using the RAMMET-X model. Upper air and surface
neteorological data from Greensboro, NC and Athens, GA were used to process the mixing heights.
iAMMET-X uses minimum and maximum daily mixing heights, and performs a temporal
nterpolation using hourly surface temperatures to produce 24 hourly mixing heights. The UAM
jreprocessor DFSNBK then spatially interpolates the mixing heights across the domain.
Wind fields were developed using the Diagnostic Wind Model (DWM). DWM spatially and
emporally interpolates observed wind data. 21 surface stations and 4 upper air stations were used
o develop the wind fields. DWM also uses a terrain file to adjust winds for terrain effects. The
tiodel was run with 13 vertical layers. The UAM preprocessor UAMWIND was then run to
iterpolate the DWM layers into 5 UAM vertical layers
The initial, boundary, and top concentration data were supplied by the Regional Oxidant Model
ROM 2.2). ROM data was downloaded from the EPA mainframe and then processed into UAM
lies through the ROM-UAM interface (supplied with the UAM model).
For further discussion of the development of UAM inputs refer to the Charlotte redesignation
emonstration and maintenance plan submitted to the EPA region IV office (NCDEIINR, 1993).
443
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Model Performance-Base Case
Model performance for the July 6-8, 1988 episode was marginally acceptable. Statistical
performance based on recommended EPA statistics (EPA, 1991) was acceptable although normalized
bias was slightly higher than the recommended range of 5-15%. The model underprcdicted ozone for
most hours, especially on day 2. Table 2 shows the model performance statistics for the North
Carolina domain. Figure 2 shows the base case ozone concentrations on day 3 at the hour of the
domain-wide maximum.
A possible cause for the underprediction on the 7th is that ROM underprcdicted boundary
conditions on that day. The transport across the boundaries on this day was from the north. A
preliminary performance evaluation of ROM results shows thai ROM severely underpredicts ozone to
the north of the North Carolina domain on the 7th (EPA, 1994). Based on observed wind speed and
direction and past ozone values measured in the Piedmont area of North Carolina, ozone values of
the magnitude measured on July 7th and 8th, 1988 are not likely to occur without transport from
other areas.
SENSITIVITY RUN RESULTS
Table 3 lists each sensitivity run and results. Table 4 shows the percent relative changes
between the base case and each sensitivity run. The model was run for 72 hours with the first day
being a startup day. Day 1 is not used in the performance statistics and is not considered in the
model results discussion.
Mixing Heights
Mixing height is defined as the height in the atmosphere below which similar diffusion
characteristics occur. The RAMMTTT-X preprocessor was used to calculate mixing heights. The
major shortcoming of this preprocessor is the overestimation of mid-morning and after sunset mixing
heights. Over estimation of mixing heights leads to an increased model volume and, in turn, to
diluted pollutant concentrations.
Two sensitivity runs were performed involving mixing heights In the initial run, mixing
heights were manually cut in half (figure 3). The winds, boundary conditions, top concentrations,
and initial conditions were then rerun. The results indicate that predicted ozone concentrations are
up to 60 ppb higher when mixing heights are reduced. The higher concentration of pollutants is due
to decreased model volume. The areas of maximum ozone prediction shifted slightly, possibly
because mixing heights are used to define the layers in the wind model. In
addition to having an effect on the chemical volumes in the model, inaccurate mixing heights will
also affect the spatial distribution and diffusion of species due to alterations in wind patterns at
various levels.
In the next sensitivity run, mixing heights were multiplied by 1.5. The region top was
adjusted from 2400 to 3600 meters to accommodate the higher mixing heights. The winds, boundary
conditions, top concentrations, and initial conditions were then rerun. The UAM predicted lower
concentrations of ozone when mixing heights were increased due to increased model volume.
Spatially, the biggest decreases, up to 25 ppb, occurred very near the areas where high ozone was
predicted by the base case.
Based on the sensitivity of maximum ozone concentration to changes in mixing heights, an
accurate representation of mixing heights is critical. Also noted was that the wind fields will be
altered by misestimation of the mixing heights, which may lead to errors in spatial distribution and
diffusion Checks against observational data should be performed where available to ensure that the
models are doing a reasonable job of predicting mixing heights
444
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Wind Speeds
Wind speeds are important in calculating pollutant dispersion in the model. The stronger the
wind, the greater the dispersion. The Diagnostic Wind Model (DWM) was used to process the wind
fields for input into UAM.
Two sensitivity runs were performed involving changes to wind. In the initial run, surface and
upper wind speeds were cut in half (figure 4). Decreasing winds reduced dispersion of ozone and
precursors and reduced transport from urban to rural areas. The resultant modelled ozone predictions
showed increases of up to 50 ppb in urban areas and decreases of up to 45 ppb in rural areas .
In the second run, surface and upper level winds were doubled. Doubling the winds caused
greater dispersion of pollutants and increased transport from urban to rural areas. Transport of ozone
across the northern boundary also increased. Ozone increased up to 30 ppb in rural areas. Decreases
of up 45 ppb occurred in urban areas.
Although higher winds will result in greater dispersion, not all areas will see an ozone decrease.
Increasing the wind speeds causes an increase in transport as well as dispersion. Rural ozone is
largely attributable to transport from urban areas.
Initial Conditions
Initial conditions refer to the concentrations present over the domain at the start of the model
simulation. Ideally, the modeled effects of initial conditions will "wash out" as the episode
progresses.
Two sensitivity runs were performed involving changes to initial conditions. In the first run,
initial conditions were set to zero. This was accomplished by multiplying the ROM initial
concentrations by 0.02, which was the smallest number by which we could multiply without
encountering problems with floating point errors in the chemistry routines. ROM was used for
boundary and top concentrations in both runs. Zero initial conditions reduced the predicted ozone
maximum on day 2 by only 1 ppb. There was no change in the ozone maximum on day 3.
In the second run, clean background values (EPA, 1991) were substituted for each species in
the initial conditions. Clean initial conditions had no effect on predicted ozone values.
Boundaiy Conditions
Boundary conditions refer to the concentrations present at the boundaries of the domain
throughout the episode. The northern boundary of the North Carolina domain borders on the
Northeast Transport Region, which contains many large industrial cities responsible for producing
large amounts of ozone and precursors. The eastern, western, and southern boundaries are "cleaner"
with the exception of a few large cities south and southwest of the domain. Since the July '88
episode was characterized by strong transport from the north, boundary conditions were thought to be
critical.
Two sensitivity runs were performed involving changes to the boundary conditions. The first
run assumed zero boundary conditions and resulted in domain wide decreases of up to 70 ppb (figure
5). ROM was used for initial and top concentrations. No increases in ozone were predicted.
The second run was with clean boundary conditions. Clean background values (EPA, 1991)
.vere substituted for each species in the boundary conditions input file. Decreases in ozone were
seen across the vast majority of the domain, with decreases of up to 40 ppb occurring along the
)oundaries.
Emissions Sensitivities
Seven emissions sensitivity runs were modeled, ail using a domain-wide across the board
missions increase or decrease. These model runs identified which areas were most sensitive to NOx
r VOC changes and therefore which areas are NO, or VOC limited. (In NOx limited areas, ozone
roduction is limited by the availability of NOx. In VOC limited areas, ozone production is limited
y the availability of VOC's.) But VOC limited areas in the base case may become NOx limited in
445
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future years or vice versa. The effect of potential future year control measures cannot be estimated
using base case emissions.
Zero Emissions
All anthropogenic and biogenic emissions in the domain were set to zero Initial, boundary,
and top concentrations from ROM were not changed. This run tested the influence of ROM data on
ozone concentrations within the domain.
Day two maximum concentrations in Charlotte decreased 55%. Day three concentrations only
decreased 27%. With no emissions from within the domain, a much larger decrease in maximum
ozone would be expected. A large amount of ozone is being transported into the domain along the
northern boundary. The maximum concentration along the northern boundary is 138 ppb. The
maximum ozone concentration in the Charlotte area with zero emissions was 104 ppb on day 3 (87%
of the standard).
The results indicate that the specification of boundary conditions in this episode is critical to
predicting the correct ozone concentrations within the domain. Also, emissions from within the
domain are relatively unimportant in contributing to ozone formation.
NOx Emissions
Two sensitivity runs were modeled to examine the effect of increasing or decreasing NOx
emissions. NO„ was initially increased by 50% and then decreased by 50% to show which areas are
NOx limited and therefore which areas may respond strongly to changes in NOx
When NOx was increased by 50% the maximum ozone concentration in the Charlotte area
increased by 4% on day 2 and 6% on day 3. The majority of the domain shows an increase in ozone
which indicates areas that are NOx limited. Areas within 5-50 km of power plants (depending on the
size of the source) show a decrease in ozone of up to 20 ppb when NOx is increased. This is due to
ozone scavenging when NOx concentrations become very high. Ozone concentrations in downtown
Charlotte stay about the same indicating the area is not NO;< limited.
When NOx was decreased by 50% the maximum ozone concentrations in the Charlotte area
decreased by 20% on day 2 and 10% on day 3 (figure 6). The majority of the domain showed a
decrease in ozone of up to 25 ppb. The largest decreases were in the urban areas where ozone levels
were highest to begin with. Downtown Charlotte showed no change in ozone concentration
indicating a small (~15kmJ) VOC limited area. Areas near power plants again showed an increase in
ozone due to the removal of NOx that was previously scavenging ozone.
The response to NOx reductions was limited by the dominance of transported ozone and
precursors into the domain. A larger reduction in ozone would be expected if the majority of ozone
in the domain was a result of local emissions. The reduction in the ozone max was greater on day 2
than day 3 due to less transport on day 2.
VOC Emissions
Two sensitivity runs were modeled to examine the effect of increasing or decreasing VOC
emissions. VOC's were initially increased by 50% and then decreased by 50% to indicate which
areas are VOC limited and will respond to changing VOC emissions.
When VOC's were increased by 50% the maximum ozone concentration in the Charlotte area
increased by 6% on day 2 and 5% on day three. Spatially, the areas where ozone increased were
very small. Only small portions of the urban areas and areas near power plants showed ozone
increases. These areas have relatively large NOx concentrations, making them VOC limited. The
additional VOC's in the sensitivity run were able to convert more NO to N02 than in the base case
resulting in increased ozone formation The maximum increase was 11 ppb of ozone in downtown
Charlotte.
When VOC's were decreased by 50% the ozone maximum in the Charlotte area decreased by
11% on day 2 and 6% on day 3 (figure 7). Again, ozone decreased in the urban cores and near the
446
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power plants. A decrease of 18 ppb was seen in downtown Charlotte on day 2 with around a 10 ppb
decrease in the other VOC limited areas.
Reducing VOC's reduces the number of radical sources available to convert NO to NO, which
is only important where excess NO exists. As would be expected, a reduction of up to 1 ppb of NO,
was seen in the same areas which had lower ozone concentrations.
Lsoprene Times Five
Isoprene emissions were increased by a factor of five in order to simulate an expected increase
in the emission factors for isoprene in the BEIS model (Pirece, 1994). lsoprene represents the largest
portion of biogenic emissions in the domain and is mainly emitted from deciduous trees. The
changes in ozone concentrations as a result of the increase were very similar to the previous total
VOC increase. The maximum increase was large in magnitude (63 ppb) but relatively small in
affected area. The maximum ozone concentration in the Charlotte area increased 11% on day 2 and
15% on day 3. The increase was limited to urban core areas and near power plants. The largest
domain wide increase occurred in the NOx plume from a large power plant in Person County, NC.
Increases in ozone were greater spatially on day 2 which had less transport than day 3. The
majority of the Charlotte metropolitan area was sensitive to increasing isoprene on day 2 with ozone
increases of 5-20 ppb. Increasing isoprene has a greater impact on local emissions than on
transported ozone. Estimating biogenic emissions could be important to modeling the ozone
maximum especially in the urban areas. Increasing biogenics in rural areas will have little to no
effect because the areas are already severely NOx limited.
Zero Elevated Point Sources
AH elevated point source emissions were set to zero. These are sources that have a potential
plume rise greater than the minimum thickness of the first layer (50 meters). In the North Carolina
domain, the majority of these sources are power plants. As a result, this sensitivity mainly reduces
point source NOx emissions.
The decrease in maximum ozone in the Charlotte area was 5% on both days 2 and 3. The
maximum domain wide decrease was 61 ppb at the same power plant as when isoprene was
increased. Ozone also increased by 45 ppb approximately 50 km downwind of the same power plant
due to the lack of NO to scavenge ozone. Ozone decreased by 10-15 ppb along the path of the NOx
plumes from the power plants. The elevated point sources had a small effect on the urban areas and
the maximum ozone concentration. If the NO:< plume is blown directly over an urban area, a larger
effect on ozone concentrations can be expected. It is unclear whether large point sources will have a
greater effect in other ozone episodes with less transported ozone. It will most likely depend on the
path of the plumes.
CONCLUSIONS
The sensitivities performed for the July 6-8, 1988 UAM episode have shown how the model
eacts to input changes and have revealed which uncertainties need to be studied further. Table 2
ihows a ranking of relative increases and decreases in maximum ozone concentrations in the
Charlotte area for each sensitivity run.
The zero boundary conditions model run clearly shows that the domain is dominated by ozone
ransported from the boundaries, especially on day 3. The majority of the transported ozone is
:oming from the northern domain boundary It is impossible to predict the correct base year ozone
'alues in this episode without accurate boundary conditions. The ROM boundary conditions are
inderestimated on day 2 and the result is a large underprediction of ozone in the entire domain. It is
mportant to have accurate ROM results in the base year as well as the future years.
Initial conditions were derived from ROM data and had no effect on maximum ozone
oncentrations in the North Carolina domain on days 2 and 3. The initial conditions are washed out
447
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of the domain by strong transport during the episode. It is not important to accurately estimate initial
conditions for this episode.
Emissions from within the domain are less important than expected. When emissions are
zeroed, an ozone maximum of 104 ppb still occurs in Charlotte due to boundary conditions. The
ozone changes resulting from emissions changes are difficult to quantify due to the dominance of
transported ozone.
In the base case, the majority of the domain is NOx limited. Changes in NOx emissions revealed
large areas sensitive to both increasing and decreasing emissions. Downtown Charlotte and to a
lesser extent other urban areas showed very little sensitivity to NOx changes, indicating VOC limited
areas. Ozone concentrations in grid cells near power plants increased when NOx was decreased due
to titration of ozone in the base case (making these areas VOC limited.) Due to the sensitivity of the
model to NOx changes, NOx inventory estimates are important.
Changes in VOC emissions affected relatively small areas throughout the domain. Downtown
Charlotte and grid cells within 50 km of power plants showed the greatest sensitivity to VOC
changes. The maximum ozone concentration in the Charlotte area was slightly more sensitive to
NOx changes than VOC changes. Decreasing VOC's by 50% reduces ozone in these VOC limited
areas, but unlike reducing NOx, it does not increase 07X>ne anywhere in the domain Creating an
accurate VOC inventory (including biogenics) is important in urban areas and near power plants, but
not as important in the rural areas. If the biogenic VOC inventory in the rural areas is large
compared to the NOx inventory, the areas will be NOx limited and therefore the exact amount of
VOC emissions is not significant.
The model is sensitive to changes in mixing heights. Decreasing mixing heights had a greater
impact than increasing mixing heights. Underestimating mixing heights will introduce bias into the
model and may lead to compensating errors.
Changing wind speeds has a large effect on the spatial distribution of ozone concentrations.
Increasing the wind speeds increases dispersion, and increases transport of ozone to rural areas.
Increasing or decreasing wind speeds has only a moderate impact on ozone maximums, but has a
large impact on model bias due to spatial shifts in ozone production.
The results of these sensitivities should not be used to make conclusions for other UAM
episodes nor for future year model runs. The emissions reductions cannot predict future control
strategies because the mix of pollutants in the future will change and ozone formation is highly non-
linear.
In North Carolina, as in many areas, there is a lack of meteorological and precursor data from
1987 and 1988 to verify model input data and model performance. Increased monitoring of
meteorological and pollutant data will reduce modeling uncertainties in the future. For the current
modeling, improvements in the most sensitive model inputs will greatly reduce uncertainty and
improve model performance.
REFERENCES
1. The Redesignation Demonstration and Maintenance Plan, l or the CharlottelGastonia Ozone
Nonaltainment Area; North Carolina Dept. of Environment, Health, and Natural Resources,
Division of Environmental Management, Air Quality Section: Raleigh, 1993.
2. Guideline for Regulatory Application oj the Urban A irshed Model. EPA-450/4-91-013; U S
Environmental Protection Agency: Research Triangle Park, 1991,p 55 and p 28
3. Posseil, Norm; Wayland, Richard, Prvltminary Evaluation of ROM for Estimating UAM
Boundary Concentrations: U S Environmental Protection Agency: Research Triangle Park, 1994
4. Tom Pierce, U.S. Environmental Protection Agency, Research Triangle Park, NC, personal
communication, April, 1994.
448
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Table 1. Highest observed ozone (ppb) during the July 6-8, 1988 ozone episode.
Charlotte Raleigh-Durham Greensboro-Winston SaJem
July 6, 1988
July 7, 1988
July 8, 1988
81
143
169
94
142
115
103
145
153
Table 2. Model Performance Statistics July 6-8, 1988.
Unpaired Highest Prediction Accuracy
Normalized Bias of all pairs > 60 ppb
Gross error of all pairs > 60 ppb
12.2%
17.1%
24.4%
1 ' V
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Figure 1. North Carolina UAM r-jdeling domain.
449
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Table 3. Daily maximums in parts per billion ozone
Scenerio
Day 1
Day 2
Sax-i
Base case
82
122
142
Multiply mixing heights by 0.5
94
154
170
Multiply mixing heights by 1.5
71
105
130
Halve surface and upper winds
100
146
149
Double surface and upper winds
72
105
143
Zero initial conditions
62
121
142
Clean initial conditions
83
122
142
Zero boundary conditions
75
79
68
Clean boundary conditions
84
123
110
Zero emissions
60
55
104
Zero elevated point sources
76
116
135
Multiply NOx by 1.5
91
127
151
Multiply NOx by 0.50
69
98
128
Multiply VOCs by 0.50
80
108
134
Multiply VOCs by 1.5
83
129
149
Multiply isoprene by 5.0
86
136
164
Table 4. Percent changes in oaone from base case.
Scenerio
Day 1
Day 2
Day 3
Zero emissions
-27%
-55%
-27%
Zero boundary conditions
-09%
-35%
-52%
Multiply NOx by 0.50
-16%
-20%
-10%
Multiply mixing heights by 1.5
-13%
-14%
-08%
Double surface and upper winds
-12%
-14%
-01%
Zero initial conditions
-24%
-01%
0%
Multiply VOCs by 0.50
-02%
-11%
-06%
Zero point sources
-07%
-05%
-05%
Multiply mixing heights by 0.5
-rl5%
+26%
+20%
Halve surface and upper winds
+22%
+20%
+05%
Multiply isoprene by 5.0
+05%
+11%
+ 15%
Multiply NOx by 1.5
+11%
404%
+06%
Multiply VOCs by 1.5
+01%
+06%
+05%
Clean boundary conditions
+02%
+01%
-23%
Clean initial conditions
+01%
0%
0%
450
-------
c>
P IL
•VL
",y' — r i n 11 n i iin i i Ti"~n 111 1111 hqi H"unr>i
69.7 ¦ 1 i lu
Figure 2. Ozone cone, in ppb for base case
3, hour 17
igurc 3. Ozone ccnc. in ppb with halved mixing heights
day 3, nour 17.
451
-------
62 .3:
61 .3
figure 4, Ozone cone, in ppb with halved wind speeds,
day 3, hour 16.
TRI
66,
HKY
•2 e.
uiyure 5. Ozone cone, in p-b with zsro boundary conditions
day 3, hour 18.
4S2
-------
•o
c
HKY
67.7
.90.
70.0
Figure 6. Ozone ccnc. in ppb with NOx decreased *Q%.
day 3, nour 17.
63.3:
[142.
HKY
o
.95.
-n i r *»1 ¦ ¦' r^T-y^.1...... n 11 f' ¦
7070
Figure 7. Ozone coic. in ppn v.ilh VOCs dosre^cd bU'i
77 .9
45.1
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Updated Land Use/Land Cover Data - Its Effects on Estimates of
Biogenic Emissions in the North Carolina Urban Airshed Modeling Effort
William W. Cure.
NC DRHNR/DEM
Air Quality Annex
15 North West St.
Raleigh, NC 27603
In North Carolina, emissions from vegetation comprise the bulk of the
volatile organic compound (VOC) inventory. Estimation of these emissions will thus
play a substantial role in the regulator)' strategy suggested by modeling. The Urban
Airshed Model (UAM), as available from the EPA presently estimates biogenic
emissions from land use/land cover dara more than 20 years old. Recent data obtained
from the U.S. Forest Service's periodic Forest Inventory and Assessment surveys have
been gridded to the modeling domain. Emission estimates based upon these data will
be compared with those from the older land use/land cover data set.
454
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Enhancements to the Emissions Inventory Inputs for the
North Carolina UAM Project
Sheila llalman
NCDEI INR/DF.M/Air Quality Section
15 N. West Street
Raleigh, NC 27603
In an effort lo belter define and allocate* both base year and projected
emissions inventories, North Carolina Division of Environmental Management, Ail
Quality Section implemented a rigorous exploration of certain aspects of emissions
inventory calculation, projection, and temporal allocation for use in an UAM analysis.
In particular, a variety of growth factors were examined, several VMT projection
methodologies were scrutinized, and default temporal allocation profiles for certain
emissions categories were studied to determine if local data existed to develop
alternative profiles. This paper presents the findings of each of the above mentioned
studies.
455
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Mobile Emission Calculations for the North Carolina LAM Project
Behshad M. Norowzi
NC DEHNR/DEM
Air Quality Annex
15 North West Street
Raleigh, NC 27603
In development of highway mobile emissions lor use in the North Carolina
Urban Airshed Model (UAM) project, the Division of Environmental Management
(DEM), Air Quality Section focused on the following aspects of the highway mobile
emission calculations.
1. A method to estimate the inspection and maintenance (I/M) program influence
in any of the North Carolina counties. The concept of I/M fractions was
developed and implemented using North Carolina Accident Data from
1988-1992.
2. Use of the daily rather than hourly emission factors in calculation of highway
mohile portion of UAM emissions inventories based on a comparative analysis
of daily and hourly emission factors for a test case.
3. North Carolina specific vehicle age distribution developed to be used in
Mobile5a runs to improve accuracy of highway mobile emission estimates.
This paper details the rationale for exploring these parameters as well as
the justification for the final decision on the mobile emission calculations.
456
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Use nf I .ink-Bare Data to Add Definition to Highway Mobile
Emissions for the UAM
Anne S. Galamb
NC DEHNK/DEM
Air Quality Annex
15 Norlh West Street
Raleigh, NC 27603
In developing highway mobile emissions for the Urban Airshed Model (UAM),
the North Carolina Division of Environmental Management (DEM), Air Quality
Section utilized link-based data, in addition to highway performance monitoring
system (HPMS) data, in order to add definition to the mobile source emissions. HPMS
data provided vehicle miles travelled by functional class per county. Link-base data
allowed emissions to be calculated for each road segment, or link, for each of the lop
three functional classes.
The link-based mobile emission estimate method was selected for Noith
Carolina because of the nature of the stale. The majority of Norlh Carolina's
population is in three city clusters (Raleigh/Durham, (irccnsboro/Winston-Salem/High
I'oint and Charlottc/CIastonia). These clusters are composed of medium-sized cities
with an average of sixty miles between the clusters. With a concentration of
population in three widespread cily centers, the link-based emissions were thought to
give a more accurate estimate of emissions and modeling results than simply allocating
the emissions over each county on a population density basis without respect to
the location of roads. This paper details the structure of the project, as well as the
quality assurance process.
457
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Quality Assurance of the North Carolina Precursor of Ozone Inventories,
Emissions Preprocessor System and the Urban Airshed Model Output
Laura lioothe and Victoria Chandler
HC UHHNR'DKM
Air Quality Annex
15 North West Street
Raleigh, NC 27603
The Urban Airshed Model (UAM) is being utilized in North Carolina as a tool
for developing regulatory strategies. In order to have confidence in the results of the
UAM output, the modeling inventories and the Emissions Preprocessor System (EPS)
outputs needed to be rigorously quality assured. North Carolina Division of
Environmental Management (DEM), Air Quality Section developed quality assurance
strategies to ensure data integrity at all phases of inventory development and
preprocessing for input into the UAM. This paper outlines the quality assurance
strategies developed and implemented for the emissions inventories that were used in
the UAM modeling effoit.
45 X
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Design of a Citizen Survey of
Forest Plant Injury Caused by Exposure to Ozone
Brian J. Morton
North Carolina Environmental Defense Fund
128 East Hargett Street. Suite 202
Raleigh. NC 27601
ABSTRACT
The North Carolina Environmental Defense Fund has designed a citizen-based survey of
forest plant injury caused by exposure to ozone. The first, pilot survey will run for ten weeks in
July, August, and September 1994. The surveyors will be trained laypersons who are donating their
time and effort. The scientific objective of the survey is to look for and collect evidence on the
incidence and severity of ozone injury to the leaves of plants and trees (seedling- and sapling-sized
plants) in the forests of western North Carolina. The educational objective is to discuss the facts and
meaning of air pollution problems hi the southern Appalachian Mountains. The third and equally
important objective involves policy dialogue: specifically, our objective is to motivate tiie surveyors
to participate in local and regional forums at which mountain air pollution is on the agenda.
INTRODUCTION
Although air quality monitoring, as currently practiced in the United States, accomplishes
important and widely understood regulatory and scientific objectives, it fails to provide the "deep
information" that is necessary for sustainable development Deep information refers to the data and
information structure that facilitates stewardship of resources for which the protection problem
includes these characteristics: the most significant sources of injury are diffuse and numerous: the
time frame over which severe arc possibly irreversible injury occurs is long-term: and ignorance of
the responses or ecosystems and human health to the stressors is high and unlikely to he substantially
improved before the onset of pathology (1). Through broadly defining stakeholders and motivating
public involvement in multi-stakeholder resource management enterprises (round tables, advisory
committees), deep information creates the conditions for effective resource management by
promoting exploration of the values that guide decisions and learning -- learning about the problem
per se as well as learning about such institutional responses to uncertainty as the precautionary
principle. In contrast, the information structure related to ozone air quality monitoring, for example,
involves a highly technical dialogue about equipment and data collection, the parties are primarily
die U. S. Environmental Protection Agency, state regulators, technicians, and atmospheric chemists.
The mismatch between the ozone information structure and the environmental problems that
the pollutant causes is especially clear in the case of the southern Appalachian Mountains. In this
rural area of the southeast, ozone levels consistently reach phytotoxic levels. Ozone injures
vegetation in multiple ways, reducing its growth and its ability to tolerate natural stresses. One
specific example must suffice to convey the environmental concerns that arise in this situation.
Thirty species of plants native to Great Smoky Mountains National Park have been shown in
laboratory studies to be sensitive to ozone at ambient levels, which typically are. below the national
ambient air quality standard of 0.12 ppm. Sixty years ago the nation expressed its devotion to the
enduring preservation cf the Smoky Mountains, and the Park's biological richness is world
renowned, but its forests are threatened by ozone. Yet the ozone information structure has not
informed the public of the threats that the pollutant poses to forest ecosystems in die southern
Appalachian Mountains.
•159
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The tailings of the ozone information structure cannot be corrected simply by grafting "bio-
indicator" monitoring onto the existing program of air quality monitoring. In fact, the U. S. Forest
Service already conducts surveys of ozone injury to plants in wilderness areas ana national forests
(2} (3). Although those surveys arc valuable, they neither include the public nor invite it to join
scientific and policy dialogues concerning the future of the forests. At a minimum, sustainable
development entails permanent protection of unique ar.d irreplaceable special places such as Great
Smoky Mountains National Park. At the process level, sustainable development requires
participation of the public, as genuine partners, in efforts ;o understand environmental problems and
the values at stake, and to develop solutions. Citizen-based environmental surveys are a means to
meaningful public participation in sustainable development efforts.
SURVEY OBJECTIVES
The North Carolina Environmental Defense Fund (NCEDF) has designed a citizen-based
survey of forest plant injury caused by exposure to ozone. The first, pilot survey will ran for ten
weeks in July, August, ar.ri September 1994. The surveyors for the pilot project will be trained
laypersons who reside in mountainous western North Carolina, which is the general locale of the first
survey.
Surveyors will learn that ozone can injure vegetation, and that czor.c-induccd injury of leaves
is expressed in certain symptoms. After training, surveyors will recognize stippling (i.e.,
pigmentation often appearing as dark scats) and yellowing (chlorosis) as symptoms in broadlear
plants of exposure to ozone during the growing season. Stippling is the most significant symptom,
being the "classic symptom" of ozone injury for broacleaf species (A). Also, the surveyors will see
ozone-induced injury to vegetarion in places that are important to them.
Thus the survey accomplishes the objective cf teaching laypersons how to recognize ozone-
ir.jured forest vegetation. Another educational objective involves the multiple effects that exposure
to ozone may cause. Ozone ir.jurv may adversely affect the whole plant by reducing photosynthesis
and growth, and increasing susceptibility to natural stresses. Ozone has the potential to affect forest
growth ar.d species composition. This information and the experience gained from the project will
provide surveyors with a background for appreciating hypotheses or. the effects on forests of
prolonged exposure to air pollution stress ar.d the assertion, made by the National Acid Precipitation
Assessment Program, that ozone is the most important pollutant for forest ecosystems (5).
The total experience offered by the survey will help to offset obstacles to public
understanding of the mountain ozone problem. First, at common ambient concentrations, ozor.e .is an
odorless and colorless gaseous pollutant. Second, ozone is net emitted but formed in the atmosphere
by reactions involving precursors which are emitted by widely dispersed biogenic and anthropogenic
sources. The survey will assist ordinary citizens with understanding the threat of ozone to forest
ecosystems by making the problem visible in a literal and tangible way.
Based on the history of other citizen-based environmental quality monitoring programs,
NCEDF's survey may help build a constituency of citizens for effective air quality regulation at local
and regional levels (5). Field trips and reports will provide good opportunities for media coverage of
air pollution in the southern Appalachian mountains. The survey may help build a larger
constituency around the nucleus formed by the surveyors.
460
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SURVEY - DESCRIPTION
Sources of Volunteers
I'd naff the pilot project, NCEDF in conjunction with western North Carolina groups of the
Sierra Cub will solicit volunteers from Asheviile. North Carolina and environs. Sources of
volunteers include, among other groups, garden c'.ubs. Sierra Club, and NCEDF. A coordinator in
Asheville working for NCEDF will assist with finding volunteers and making local arrangements for
training, field trips, and publicity.
Training and Certifying Volunteer Surveyors
Surveyors must be .able to collect two basic types of data: data on incidence and data on
seventy Are symptoms of injury present? How bad is the injury?
Surveyors wil] receive training fron the United States Forest Service and National Park
Service. Training will follow a curriculum developed jointly by the Forest Service, National Park
Service, and NCEDF. Surveyors will be taught how to identify the targe: bio-indicators; to select
individual plants; to recognize symptoms of ozone injury and mimicking symptoms; to quantify
visible ozone-induced injury; to select leaf samples; and to document observations.
The indicator species for the pilot project arc the following plants and trees: black cherry,
ye'.lcw poplar, sweet gum, blackberry, tall (poke; milkweed, winged sumac, crown-beard, and cutleaf
coneflower. They arc common in Lie southern Appalachians in meadows, woodland borders, and
woodlands. All have been studied in fumigation experiments and hence their sensitivity to ozone
and symptoms are known.
Interveir.ai stipple is the target symptom for the pilot project. This symptom appears as
pigmented dots or. the upper side of a lea: oetween veins. Another characteristic that in some
situations aids diagnosis is "leaf shadow:" an upper, overlapping leaf reduces the sunlight reaching
the lower leaf, greatly diminishing stippling, a photosensitive response. To reduce misdiagnosing
lea: injury, surveyors will be trained to recognize mimicking symptoms which express normal leaf
agirg, site and soil conditions, and attack by pests anc pathogens.
Surveyors will also be trained in two measures of severity: the overall amount of ozone injury
to a plan: and the degree of stippling. The first measure indicates the proportion of leaves on a plant
that are injured. The second measure indicates, for an average of several most injured leaves, the
proportion of leaf area that is srippled. Both measurements will be made according to the protocol
of the Forest Health Monitoring Program; this protocol uses scales with six classes (7).
Training is scheduled to occur on July 30 at the Bent Creek Experimental Forest near
Asheviile. The training session will last about six hours. Every surveyor will be required to
participate in the training session and to pass a written and laboratory examination before collecting
data on ozone injury.
Data Collection Plan
NCEDF has established four criteria for data collection: 1) data that are usable by the federal
land managers interested in improving mountain air quality; 2) site selection (geographical and
temporal) that has the potential to illustrate the correlation of exposure with elevation and
topographic position (e.g., on a ridge, in a cove); 3) repeated observation to monitor the progression
of symptoms as exposure accumulates: and 4) volunteer direction of the survey.
By collecting data that will be used by federal land managers, the surveyors' efforts will
complement the National Forest Health Monitoring survey and the Forest Service's Class I
wixemcss area surveys. The purposes of these surveys are to document the geographical
distribution of ozone injury and to quantify the severity of injury. The volunteer surveyors will use
the seme quantitative Injury standards and data collection forms as the Forest Service. Also, site
selection for this project should either increase the thoroughness of the surveys or add to the territory
that will be covered.
461
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The location of sites at three elevations will suffice to convey how cumulative ar.d peak
ozor.e exposure tends to increase with elevation. Repeated observation at two-week intervals will
ensure that surveyors see the progression of symptoms. Depending on the number of surveyors and
their commitment, the actual scope of data collection may require some adjustment or truncation.
The surveyors will transfer data to the coordinator. The coordinator then will review and
manage the data, store data sheets In files, and send copies of the records to participating federal land
managers. The coordinator will also serve as the liaison between surveyors and data users; this
function includes communication about the quality of the data.
Because the surveyors arc partners in the project, their preferences should influence such
important dimensions of the project as the timing of field trips and site selection. Data collection is
scheduled to occur on three weekends: August 6, August 20, and September 3. Volunteers are free
to choose either Saturday or Sunday in each weekend. To observe the progression of symptoms,
volunteers will need to conduct surveys on all three weekends.
The project will be most effective if the volunteers survey plots in locations that are
meaningful to them: for example, a ridge with a beautiful view, a favorite cove, a woodlands near
their house. NCEDF and the Forest Service staff will work with surveyors to provide them with
maximum freedom of choice while ensuring that their data are useful to federal land managers.
Quality Assurance and Quality Control
At this time, the objectives and procedures for quality assurance and quality control are still
being developed. Nonetheless, some of the objectives are clear. Surveyors must be able to perfectly
identify the bio-indicators and to measure severity within one class at least 80% of the time.
Surveyors will collect leaf samples and send them to the Forest Service for verification. Incorrect
species identification will result in rejection of data. Cross-crew checking may be employed.
Publicizing Survey Methodology and Results
An important goal of the project is to educate the public in western North Carolina about
ground level ozone and other pollutants affecting the southern Appalachian mountains. Volunteer
surveyors will quite likely help achieve this goal through ad hoc efforts-conversations with friends,
informal discussions at Siena Club meetings. To achieve the widest dissemination of results from
the project, NCEDF will oversee the writing of a formal report at the conclusion of the pilot survey.
This report will be distributed to the surveyors, federal land managers, government officials
interested in mountain air quality, the general public, and the media. The report will assist surveyors
with communicating about mountain air quality in more formal modes: discussions with governipent
officials, letters to the editor and op-ed articles, speeches, and presentations.
CONCLUSIONS
Efforts to preserve the Great Smokies and other special places in the southern Appalachians
by establishing national parks (and later wilderness areas) have failed to protect these areas from air
pollution. As Tony Hiss observes in The Experier.ce of Place, effons to protect landscapes depend
upon people who personally know places, through their own senses, and have reflected on thetr
"responses, thoughts, and feelings to help us replenish the places we love" (Si I doubt that the
public's involvement in any policy dialogue or. the southern Appalachians can be widespread or
meaningful as long the ozone problem remains invisible and intangible. A citizen-based survey of
forest plant ir.jurv caused by ozone will help deepen the public's understanding of the ozone problem
in the southern Appalachians. The survey will provide the conditions for citizens to rationally
evaluate adding their own efforts to protecting the mountains fror- air pollution and will help to
broaden the case of support for strengthening the policies that pro • ide air quality protection for the
southern Appalachians. A rigorous methodology will help ensure that the survey achieves all its
objectives: scientific, educational, and motivational.
462
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REFERENCES
1. Felleman. J., "Deep information: the emerging role of slate land information systems in
environmental sustainability;" woricing paper, Lincoln Institute of Land Policy, Cambridge,
MA. 1992.
2. Brantley, E. A. and Tweed, D.: "Ozone injury to bioindicator foliage in the southeast region 8
class one wilderness areas - 1993," report #94-1-26; U. S., Department of Agriculture, Forest
Service, Southern Region, Asheville, NC, 1994.
3. Letohn, A. S.; "Ozone exposures within or near national forests in North Carolina, South
Carolina, and Tennessee;" A.S.L. & Associates, 111 North Last Chance Gulch, Helena, MT,
59601. n.d.
4. Skeily, J. M. et al., eds.; Diagnosing Injury to Eastern Forest Trees-, Pennsylvania State
University, College of Agriculture, University Park, Pennsylvania, 1987; p. 4.
5. U. S., National Acid Precipitation Assessment Program; 1992 Report to Congress:
Washington. NAPAP Office of the Director, 1993; p. 5.
6. See, for example, issues of The Volunteer Monitor, a national newsletter about citizen-based
environmental monitoring projects.
7. Brantley, B. A.; "1993 field manual: identifying ozone injury of sensitive plant specks," U.
S., Department of Agriculture, Forest Sen/ice, Asheville, NC, 1993.
8. Hiss, T., The Experience of Place, New York, Vintage, 1991, p. xii.
463
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Auburn Tower Ozone Study 1993
George C. Murray, Jr.
Thomas L. Manuszak
Robert S. Graves
M. Jeffrey Gobel
NC Department of Environment, Health, and Natural Resources
Division of Environmental Management
Air Quality Section
Ambient Monitoring Branch
15 N. West Street
Raleigh. North Carolina 27603
ABSTRACT
The Raleigh-Durham area has been designated as a moderate non-attainment area for ozone
because of measured excessive ozone concentrations. Redesignation proceedings are in progress for
this area. The Auburn Tower, a 2000 foot broadcasting tower located about 10 miles southeast of
Raleigh, provided the opportunity to perform multiple elevation atmospheric sampling. A study was
designed to measure the ozone concentrations and organic compounds at three elevations. Three
ozone monitors, hydrocarbon samplers and carbonyl samplers began sampling on July 23, 1993.
Organic compounds were collected by contract laboratories who changed canisters and DNPH
reagent cartridges and analyzed the samples. The organic sampling results are discussed in other
related papers. Sampling continued until September 3, 1993 when all ozone equipment was audited
and disconnected. Ozone was monitored continuously, 23 hours a day with one hour set aside for
nightly automatic zero/span checks. Long sampling lines and probes were attached to the tower from
each elevation down to the air conditioned room used for the ozone monitoring equipment. Heated
lines and water traps were used inside this air conditioned room. The ozone concentrations
measured are presented graphically. The normal diurnal pattern seen at ground level monitoring
was not seen at 820 foot and 1420 foot elevation. Daily averages and maximums were larger at
elevated levels. The average ozone concentration at ground level for August was .034 ppm and at
1420 foot level the average was .061 ppm. The maximums at ground level for August was .094 ppm
versus the maximums for August at 1420 foot level was .105 ppm. The study will continue in 1994.
INTRODUCTION
The Air Quality Section of the North Carolina Division of Environmental Management is
charged with protecting the ambient air quality within the state. Part of meeting this goal is to
measure the amount of ozone in the ambient air. Ozone, a respiratory irritant, is regulated by both
federal and state ambient air quality standards. The Raleigh-Durham area has been designated as a
moderate non-attainment because of measured excessive ozone concentrations. The opportunity to
perform upper air sampling in this area is of value in understanding the ozone problem and what
ozone precursor pollutants are responsible for the ozone problem. The Auburn television tower,
located about 10 miles south of Raleigh, North Carolina provided the opportunity to measure ozone,
hydrocarbons and carbonyl compounds at near ground level, 820 foot level, and 1420 foot level.
Access to the upper levels was by a two-man elevator in the center of the tower. The platform at
each level was large enough to allow installation of sample probes and to support several small
cabinets to house test equipment. The cabinets were used for hydrocarbon and carbonyl samplers.
Ozone monitors and calibrators were located in a temperature controlled building at the base of the
tower. Ozone sampling was done using long sample lines of PEP tubing to the ozone analyzers at
ground level (approximately 320 feet above sea level). Access to the tower levels was limited to
Tuesday through Fridays. The knowledge gained by others in a multi-level ozone study in
California was helpful in designing this study (1)(2).
464
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DISCUSSION
The sample probe assembly for the 820 foot and 1420 foot levels consisted of a 1/4" FEP
lire in a stainless steel tubular probe support. The quarter inch line connected to a 90mm Teflon®
fiitcr holder equipped with a Teflon® particulate filter which was connected to long 5/8" diameter
FEP lir.es. Each probe support extended approximately 2 meters away from the tower platform with
approximately a 60 degree downward bend to minimize precipitation entering the probe line. To
further minimize the moisture/precipitation problem, the FEP lines stopped 2 feet inside the end of
the s:air>!ess steel support. A contractor installed the sample lines and probes on the tower.
Ozone was measured using the ultraviolet photometric detection principle. A Dasibi 1003
AH analyzer was used for each level. These instruments are designated by EPA as "equivalent
methods". A single, photometer-type calibrator was used to minimize variability in calibrations and
routine checks. The output of the monitors were connected to a data logger and to a "back-up" data
system.
Ozone Data Collection
The ozone monitors were installed at the tower on July 15, 1993. The instruments were
allowed to warm up and stabilize with adjusted calibrations being done on July 20 and 21, 1993.
All equipment and probes were connected and start-up officially began on July 23, 1993 about 16:00
hours. An audit was performed on July 30, 1993. Sampling continued until September 3, 1993 at
13:00 hours when all equipment was audited and removed. A total of 41 days of data were
collected. The data completeness was excellent.
Ground level - 92.47% complete
820 foot level - 92.89% complete
1420 foot level - 96.54% complete
Water was noted in the ground level and 820 foot level sample lines early in the project as
shown in Fable 1. On August 12, heat tape was installed at the ground level probe assembly on the
intake lines in the air conditioned building. No other water or moisture problems were noted.
Some data was invalidated for these two levels for the days shown in Table 1.
Initial Calibration
The initial calibration of the ground level instrument was done on July 21, 1993 using a
certified 1003 PC Dasibi calibrator.
The medium level (820') was calibrated on July 21, 1993 and the high level (1420') was
calibrated on July 20, 1993 using the same calibrator. The percent differences from the data logger
were r.oted after these calibrations (See Table 2). No data were reported until July 23, 1993, when
the conditioned probe lines were installed and vacuum leak checked.
Calibrations are normally conducted quarterly (ninety-one days maximum). Since this
project, only ran forty-one days, the initial calibrations were the only calibrations conducted. Two
accuracy audits were performed on this project, on July 30, 1993 and on September 3, 1993. This
was sufficient to support the quality of the collected data.
Routine Visits
Each ozone analyzer was subjected to an automatic zero and span check performed on a daily
basis in the early morning hours (3:00 am until 6:00 am). These check results and the hourly ozone
averages were reviewed daily via modem hook-up at the main office. The zero and span checks
were used to determine whether a site visit was needed for further checking. To perform automatic
zero and span checks, an artificial test atmosphere at zero and one span concentration was
introduced into each analyzer. The span gas concentrations were about 70-90 percent of the
analyzer's nominal operating range (.350 - .450 ppm).
Eighteen site visits were made during the 6 weeks of ozone monitoring. These visits were
made by an Environmental Chemist in order to foresee any problems which might occur. All
instrument checks, calibrations, and precision points followed EPA approved State SOP/QA
procedures (3).
465
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A special barometer was used to check the line pressure at the elevated levels. The lir.e
pressure was used to calculate each instrument's span number during the set up, calibrations, ar.d
routine checks. Upon completion of the checks, the. span numbers were set to values based upon
average barometric pressures at each level. These, readings were used to show the line pressures
were stable and that the particulate loadings on the up-tne-tower particulate filters were not
significant.
Precision/zero/span checks were performed biweekly by the site operator following approved
procedures. Other routine operational checks were documented in the ozone monitor logbook
during each site visit. The purpose of these checks were to ensure that the air monitoring station
and all levels were operating properly and within prescribed parameters as indicated in the State
SOP/QA Plan. Frequent manual zero/span checks were used to determine the need for analyze*
adjustments. No adjustments were needed during this study. To perform the manual zcro'spar.
checks, artificial test atmospheres at zero and one span concentration. (.350 - .450 ppm) were
introduced into each analyzer through the 47mm particulate filter. During these checks, the
analyzers operated in their normal sampling mode, except the span number for the two tower
monitors, were adjusted to reflect average ground barometric pressure for the checks. These test
gases were introduced to the particulate filter on the back of the analyzers via a solenoid valve and
thus did not go through the particulate filter which was on the tower. Precision checks were
performed in the same manner as manual span checks, except the precision check concentration was
about 16-20 percent of the analyzer's full scale range (.08 - . 10 ppm). The gaseous standards for
'he span and precision concentrations were obtained by an ozone generator with ozone
concentrations determined by a currently certified ozone transfer standard.
Accuracy Audits
Accuracy is the difference between the analyzer response and the reference value obtained
during the multipoint instrument audit. Accuracy audits were performed at the start-up and end of
this project. The audits were performed by the Electronic and Calibration Unit (ECU) and not the
normal site operator. The audit calibrator was certified against a primary standard quarterly. The
monitors were operated in their normal sampling mode and the audit gas passed through the 47mm
existing particulate filters on the monitor inputs.
After the analyzer and calibrator stabilized, ten analyzer readings, calibrator readings and
recorder readings were taken. The average of the ten readings were compared to the average of the
corresponding one minute data logger valves. This procedure was used for each audit point.
The percent difference for each audit point was calculated following 40CFR58 Appendix A
procedures. The accuracy audit results are shown in Table 3.
Sample Line Residence Times
The long FEP sampling lines (820 feet. 1420 feet) were .625" OD with .045" walls. The
residence time for each level was calculated including the 130 feet of tubing to get the sample lines
into the sampling building. The flow was 10 liters per minute using a helper pump. Both the inlet
and outlet of the analyzers were connected to the lines from the tower. The monitor pumps were
therefore not pulling against the vacuum created by the long sample lines. The sample residence
times for the two elevated sample lines arc found in Table 4. The ground level 1/4" FEl' sampling
line had a residence time of less than three seconds.
Ozone Line Loss
To minimize line loss, the .625 inch sample lines were conditioned with 2 ppm of ozone for
seven days at a flow rate of 5 1pm prior to installation on the tower. Teflon® inlet filters were used
on the lines near the intake on the tower to prevent particulate matter from entering the sampling
lines. These filters were also conditioned with ozone to minimize the potential ozone scavenging.
Since the residence times are not within the time period recommended by EPA for the two
elevated sampling locations, line loss ozone studies were conducted near the beginning of the project
and at the end of the project. Line loss data was collected on July 30, 1993 and September 3, 1993
are shown in Table 5. The line loss tests were conducted by taking a certified calibrator to each
466
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467
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Table 1. Line Moisture
Date Finding
August 4 Water in ground ami 820 foot probe lines
August 5 Water in ground and 820 foot probe lines
August 6 Water in ground and 820 foot prohe lines
August 10 Water in ground probe line
August 12 Water in ground probe line
Table 2. Calibration Difference from Datalogger
Calibration Point Ground Medium High
Zero 0% 0% 0%
.450 ppm .4% 0% .5%
.030 ppm 0% 0% .3%
.150 ppm .1% \A%
.050 ppm 0% 1.9% 0%
Table 3. Accuracy Audit Results
Audit Concentration Points (ppm)
.06-.08 .16-.18 .34-.45
Locution Date % Diff % Diff % Diff
Ground 7/30/93 -6.7 -2.9 -2.0
Ground 9/3/93 -2.7 -0.6 +1.0
820 feet 7/30/93 -2.7 -1.8 +1.0
820 feet 9/3/93 -1.4 +0.6 +0.5
1420 feet 7/30/93 +2.9 +1.8 +2.1
1420 feet 9/3/93 -1.4 +0.6 +2.0
Table 4. Residence Time
Tubing Size
0.625
0.625
0.25
Wall
0.045
0.045
0.030
Cross Sec.
1.45
1.45
0.18
Length
1550
950
15
Volume
68484
41974
81
Residence
6.85
4.20
0.04
Table 5. Auburn Tower Ozone Line Loss Results
Location
Date
% Difference
Ground
7/30/93
Monitor was 7.1 % lower than PC
9/03/93
Monitor was 9.1 % lower than PC
820 feet
7/30/93
Monitor was 8.75 % lower than PC
9/03/93
Monitor was 14.3 % lower than PC
1420 feet
7/30/93
Monitor was 17,9 % lower than PC
9/03/93
Monitor was 5.6 % higher th3n PC'
* High winds and low ozone concentrations during this measurement.
-------
level. The calibrator was warmed up for 30 minutes before any readings were Laker). At c?,ch
level, thirty (30) readings were taken from the calibrator while sampling ambient air. All values
were corrected for zero off-set of the instruments. At the ground level, the thirty readings were
recorded after waiting the calculated residence time to the nearest minute. The average results from
the up-the-tower measurements from the calibrator were compared to the appropriate monitor
average response to approximate the loss of ozone in the long sample lines. On both days, it was
windy at the 1420 foot level. On September 3, 1993, a towel was draped over the calibrator to help
retain the cell temperature. The cell temperature achieved on the tower was 33°C to 34 °C, which
is lower than normal. The September 3rd measurements at 1420 feet were based on relatively
unstable and low (- .02 ppm) ozone concentrations and are therefore not representative of most
measurements during the study. Since September 3rd was the last day of tower availability, no
further testing was performed.
CONCLUSIONS
Valid ozone information can be obtained using this technique, though quantifiable line loss
occurs. The normal diurnal pattern seen at ground level monitoring was not seen at 820 foot and
1420 foot elevation. The patterns were flatter at the higher elevations. The daily averages and
maximums were higher at elevated levels. The average ozone concentration at ground level for
August 1993 was 0.034 ppm and at the 1420 foot level the average was 0.061 ppm. The highest
daily maximum one hour reading at ground level for August 1993 was 0.094 ppm versus the
maximum of 0.105 ppm at the 1420 foot level. The ozone data are presented graphically in
Figure 1. These data are not corrected for line loss. This study will continue in 1994.
Note: The mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
REFERENCES
(1) Bush, David; Molik, Larry; Pankratz, David, "Multi-Level Ozone Measurements -
Methodologies and Results," in AWMA 86th Annual Meeting Proceedings, Volume Two; Air
and Waste Management Association: Denver, 1993; 93-MP 14.03.
(2) Pankratz, David V., Bush, David; The Study of Temporal and Vertical Ozone Patterns at
Selected Locations in California, Air Resources Board Contract A132-165; California Air
Resources Board, 1993, pp. 15-16.
(3) Procedures for Standard Operation and Quality Assurance, "Ozone Using a Dasibi
Continuous Monitor and Data Logger", North Carolina Department of Environment, Health
and Natural Resources, Air Quality Section, 1991; Section 2.7.
469
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Vertical Distributions of Carbonyls
in Urban North Carolina
Viney P. Aneja, Jay H. Lawrimore, Mita Das, and Fred Stratton
Department of Marine, Earth, and Atmospheric Sciences
North Carolina State University
Raleigh, North Carolina 27695-8208
Brian R. Hopkins and Thomas P. Murray
Department of Chemistry and Industrial Hygiene
University of North Alabama
Florence, Alabama 35632
William G. Lonneman
AREAL, U. S. Environmental Protection Agency
Research Triangle Park, North Caroiina
George C. Murray
North Caroiina Department of Environment, Health and Natural Resources
Raleigh, North Carolina 27626
INTRODUCTION
Low moiecular weight carbonyl compounds such as formaldehyde and acetaldehyde
are intermediates in atmospheric photochemical processes as well as pollutants with
well known human health risks.! Aldehydes arise from direct sources such as
factory emissions and automobile exhaust as well as indirect sources such as the
oxidation of hydrocarbons. The carbonyl compounds are precursors of the carboxyiic
acids and play a prominent role in free radical production.^
Numerous studies have reported diurnal variation of carbonyl compounds in both
urban3 and rural areas') but there have been few studies which explore the vertical
profile of carbonyls. Since many carbonyl measurement technologies require either
integrated sampling or equipment not amenable to aircraft platforms, the profiling
of carbonyls, particularly formaldehyde, is problematical?
This study takes advantage of a unique sampling platform for measuring the
vertical profiles of carbonyls. The platform, known as the Auburn Tower, is a 610
meter television tower located approximately 15 km southeast of do\vntown
Raleigh, N. C. The tower was equipped for sampling at the surface and at platforms
located at 250 and 426 meter elevations.
470
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METHODS AND PROCEDURES
Access to the tower was limited to four days per week. Tuesday through Friday, with
a single integrated three hour sample collected between 0500-0800 hours. The
carbonyl sampling system consisted of a pump (Parker Metal Bellows MB151)
connected to the sampling cartridge which was in turn connected to a 1 meter, KI
coated, copper, ozone denuder tube. An electric solenoid was located between the
denuder tube and the cartridge. The pump and solenoid were connected to a timer
for unattended operation and flow meters were used to calibrate the pump before
and after sample collection.
Sampling was with Waters Sep Pak C-1S "Classic" cartridges coated with acidified
2,4-dinitrophenvlhydrazine. The cartridges were prepared at the University of
North Alabama, shipped to the field site for exposure and returned for elution and
analysis by high performance liquid chromatography (HPLC). The HPLC was an
LDC Milton Roy Constnmetric 3000 system equipped with a variable wavelength UV
detector (360 ran) and a 10fJ.L Rheodyne fixed loop injector. Isocratic elution with
60 : 40 acetonitrile-water was used for samples and standards. The HPLC was
calibrated using 2,4-cinitrophenylhydrazone standards that were carefully weighed
and serially diluted.
A method detection limit, defined as three times the standard deviation of the field
blanks, gave the following results in which the (ig / cartridge value for each analyte
has been converted to ppbv by assuming a 120 L air sample. Precision sampling
experiments revealed no statistical difference (t-test) in the results obtained from
each cartridge. Sequential gave good results on formaldehyde (>92 %) but resulted
in considerable breakthrough with aceraldehyde, acetone and propanal.
The average concentration of each analyte at the three sampling elevations is shown
in the following table.
Detection Limits
Methana! Ethanal Acetone Propanal
ppbv 0.166 0.159 0.208 0.115
Average Concentration of Analytes in Ambient Air (ppbv)
Methanal Ethanal Acetone Propanal 2-Butanone
426 Meters
250 Meters
Surface
2.54
2.63
0.80
0.14
0.13
0.08
0.09
0.05
0.05
0.04
0.04
0.03
0.01
0.01
0.01
-------
RESULTS
A major concern in this study was the background level of carbonyls in the blanks
since the sampling cartridges were allowed to remain in the sampling apparatus, on
the tower, for a minimum of 21 hours and in the case of samples taken on Tuesday,
the cartridges were placed on the tower the preceding Friday. Blanks for this study
were compared with the average blank levels for a number of other field studies,
with carbonyls analyzed at the University of North Alabama, dating to 199Q. The
results for formaldehyde are shown in Figure 1, where the error bars represent one
standard deviation. In the case of the commercial precoated silica cartridges and the
UNA C-1S cartridges, the data shown is for laboratory blanks. The blank levels for
formaldehyde in this study compare favorably to other studies where the cartridges
were taken directly from and returned to a freezer before and after sampling.
The levels of formaldehyde at the surface averaged 0.80 ppbv but at higher
elevations the concentration increased substantially as shown in Figure 2. The
surface level results are not surprising given the fact that sampling occurred in the
early morning hours after much of the ozone and formaldehyde had deposited.
The ozone-formaldehvde correlations shown in Figure 3, show no correlation at the
surface. At the higher elevations, probably above the inversion layer, the
formaldehyde levels are higher and correlate better with ozone measurements
taken at the respective levels on the tower.
An attempt was made in this study to determine the concentrator, of 2-butanone.
Appropriate hydrazone standards were prepared but the field sample levels were so
low (maximum value 0.14 ppbv) that this measurement appeared unreliable and no
detection limit was established.
BIBLIOGRAPHY
1. Carlier, P. R.; Hannacni, H.; Mouvier, G. Atmospheric Environment, 1986, 20,
2079-2099.
2. Atkinson, R. Atmospheric Environment, 1986, 24A, 1-41.
3. Grosjean, E.; Williams, E. L.; Grosjean, D. J. Air Waste Manage. Assoc., 1993, 43,
469-474.
4. L ee, Y. N.; Zhou, X. Environ. Sci. Techno!., 1993, 27, 749-756.
5. Vairavamurthv, A.; Roberts, T- M.; Newman, L. Atmospheric Environment, 1993,
26A, 1965-1993.
-------
^Formaldehyde per cartridge. Error bars i 1 o
Kinlerbush 1990 -
I ~ 1
>
<
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-------
FORMALDEHYDE
8.00
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Figure 2
OZONE AND FORMALDEHYDE ALL LEVELS
Ozone-426 1 ~ "-^12
Ozone-253 r2 = 0.314
Ozone-Surface _ q qoO
O c4 no x
Formaldehyde ppbv
Figure 3
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SESSION 10:
QUALITY ASSURANCE
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Intentionally Blank Page
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A Statistical Analysis of 40CF;R60
Compliance Test Audit Data
William J. Mitchell, Jack C. Suggs and Ellen W. Streib
U.S. Environmental Protection Agency
Atmospheric Research and Exposure Assessment Laboratory
Research Triangle Park, NC 27711
ABSTRACT
The U.S. Environmental Protection Agency (EPA) provides audit materials to
organizations conducting compliance tests using EPA Test Methods 6 (S02), 7 (NOX), 18
(organics by GC/FID), 25 (organics as pprn C), and 26 (HC1). These audit samples must be
analyzed and the results reported to the regulatory agency along with the compliance test
results. Each regulation specifies accuracy (% bias) limits that must be achieved on the audit
samples. Failure to meet these accuracy limits may invalidate the compliance test results. A
statistical analysis was done using the results from 5,926 compliance audits to determine if
the limits will be achieved by most organizations. This analysis determined that they are
likely to be achieved more than 90% of the time for Methods 6, 7 and 26 and also for some
of the organics measured by Methods 18. However, they are not likely to be achieved even
50% of the lime for Method 25 and for many Method 18 measurements.
INTRODUCTION
Our laboratory provides audit materials to organizations who are conducting
compliance tests using HPA Test Methods 6 (SO.), 7 (NO,), 26 (HCI), 18 (organics by GC),
and 25 (organics as ppm C).'' Each test method specifies accuracy (% bias) limits the
organization being audited must achieve on these audit samples to demonstrate that it is
proficient in using the test method. These limits are:
% Bias Limits
Method Lower Upper
6 ¦5% 5%
7 -10% 10%
18 -10% 10%
25 -20% 20%
26 -10% 10%
If the audited organization fails to meet these limits, the regulator,' agency may reject
the compliance test results.
The HPA limits were established from small scale studies conducted while the
compliance test methodology and the regulations were being developed. KFA's goal was to
establish audit test limits that would be achieved ar least 90 times out of each 100 tries. Was
this goal achieved? We examined the 5,926 audit test results reported to date to answer this
question.
477
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DESCRIPTION of AUDIT MATERIALS
Method 6 (S02). The audit samples <2 per compliance test) are aqueous solutions of
H2SO., in glass ampoules. An aliquot of the audit sample is diluted with 3% H.O, and this
solution is then analyzed using the Method 6 titration procedure. When diluted the audit
sample simulates a Method 6 stack sample equivalent to a stack gas concentration between
100 and 3000 mg SO, per dry standard cubic meter (DSCMV
Method 7 (NOj. The audit samples (2 per compliance test) are aqueous solutions of
KNO, in glass ampoules. An aliquot of die audit sample is diluted with the appropriate
Method 7 sample collection solution and this solution is then analyzed by the same method as
used for the compliance samples. When diluted, the audit sample simulates a Method 7 stack
sample equivalent to a stack gas concentration between 100 and 2000 rag NO./DSCM.
Method 18 (Organics by GC). Each audit sample (one to two per compliance test)
contains one organic compound at the ppm level in a compressed gas cylinder with N, as the
balance gas. The auditee attaches his own regulator and transfer line to the cylinder and
transfers a representative sample from the cylinder to his sampling train either directly (e.g.,
filling a Tcdlar bag) or through a manifold. The collected sample is then analyzed exactly as
the stack samples.
Method 25. (Organics as ppm C). Each audit sample (two per compliance test)
contains three organic compounds at ppm levels and 5% CO; in a compressed gas cylinder.
The balance gas is N2. Two concentration levels are available (50 to 300 ppm C. and 700-
2000 ppm C). The auditee attaches his own regulator and gas transfer line to the audit
cylinder and collects a representative sample in his Method 25 sampling train. The collected
sample then is analyzed exactly as the stack samples are analyzed. The auditee reports the
results as ppm C.
Method 26 (IIC1). The audit samples (two per compliance test) are aqueous
solutions of KC1 in glass ampoules. An aliquot of the audit sample is diluted with 0. IN
II,S04 and this solution is analyzed for chloride by ion chromatography. When diluted, an
audit sample simulates a stack sample containing between 10 and 50 rng chloride/IXSCM.
STATISTICAL ANALYSIS of RESULTS
The bias statistic for each audit was calculated as follows: the expected concentration
value was subtracted from the reported value and this difference was then divided by the
expected value. Our statistical analysis procedure employed the bi-weight function of
Mostellar and Tukey The center measure of the distribution of % bias was estimated as a
weighted average.
y = S iv, yt 1 T. uv
where y. is the % bias for the i" audit with weights.
The median absolute deviation (M AD) is defined as
478
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v, - mediy) y - med{y)
1- - — — when -- L <1
( 6(MAD) 6 (MAD)
0 otherwise.
MAD = median | y; mediy) |
where med(v) is the median of the % bias values.
I'he MAD is approximately 2/3 the true standard deviation if underlying conditions
are normal. Therefore, the bi-weight allows bias values that are within approximately ± 4
standard deviations to be averaged as a measure of the center of the % bias distribution.
The spread of the % bias distribution is estimated as the asymptotic variance of the
bi-weight
nY.
-------
N is the number of audit results used to calculate the probability limits and U and L are the
upper and lower probability limits, respectively. For example, Table 1 shows that 90 out of
100 Method 6 audit results will lie between +4 and -4% and that 90 out of 100 Method 7
results will lie between +10 and -10%.
Table 1 (Probability Limits for Method 6,7 and 26 Audits): Table 1 shows that more
than 90% of the % biases for Methods 6,7 and 26 met the applicable acceptance limits and
that the data are essentially symmetrically distributed about zero.
Table 2 (Probability Limits for Method 18 Audits): Thirty-one compounds have been
used in Method 18 audits, but only 14 have been used in at least eight audits — the minimum
number of audit results required for calculating the probability limits. Table 2 shows that
chloroform is the only one of these 14 that will yield % biases meeting the present Method
18 limits of ±10% at least 90% of the time. It also shows that with four exceptions
(ethylene, methyl ethyl ketone, perchloroethylene and vinyl chloride) the % biases for these
compounds will be approximately symmetrically distributed about zero with mean % biases
less than 5 %.
Table 3 (Probability Limits for Method 25 Audits): Table 3 shows that less than 75%
of the % biases for the high concentration samples and less than 50% of the % biases for the
low concentration samples will meet the Method 25 limits of ±20%. It also shows that the
mean % bias for the low concentration audit samples will be +16% and that for the high
concentration samples will be -6%. Because the number of audit results used is large and
since the influence of outliers has been neutralized, one has to assume that these biases are
real.
CONCLUSIONS
Since the limits for Methods 6, 7 and 26 are being achieved routinely, they should
remain unchanged. In contrast, the bases for the original limits for the majority of the
Method 18 compounds and for Method 25 need to be examined to decide if new limits are
required. For example, if the limits were simply widened to ±30%, this audit limit would be
achieved 90% of the time for 8 of the 14 compounds shown in Table II Alternately,
compound-specific limits could be established for Method 18 rather than using identical limits
for all of the compounds. In the case of Method 25 any new limits should compensate for the
biases present in Method 25. For example, the limits could be widened to ±50% and
adjusted for the biases associated with each concentration level (i.e. high concentration -6%;
low concentration +16%). Then, more than 95% of the high concentration audit sample and
75% of the low concentration audit sample results would meet these new limits.
REFERENCES
1. Title 40, Code of federal regulations, part 60, appendix A -" Test Methods". Office
of the Federal Register, National Archives and Records Administration, Washington,
DC. July 1, 1992.
2. Title 40, Code of federal regulations, part 61, appendix B Test Methods". Office
of the Federal Register, National Archives and Records Administration, Washington.
DC. July 1, 1992.
3. Mostellar.F., Tukey.J.F..; Data Analysis and Regression, Addison Wesley Publishing
Co., Reading MA, 1977, pp 205 - 208.
480
-------
DISCLAIMER
The information in this document has been funded wholly by the United States
Environmental Protection Agency. It has been subjected to Agency review and approved for
publication. Mention of trade names and commercial products does not constitute
endorsement or recommendation for use.
1. Probdb': ty limits for method 6. 7 and 26 audi ts.
P-obdbi iitjLi LUlts_inJLB AS
"est
Mean
95/100 90/:
OC
7b/1C0
/'
_oo
Pcthcc
CorrDC^rd
•N
% Bias
L U l
u
L U
11
0
S02
3593
-Z.2%
- 5 5-4
4
-3 3
„ n
!
7
NOx
166,-
G m
-II 13 -10
0
-6 8
-4
i
2G
HCi
93
0 91
-12 9 9
7
C 5
4
2
Table 3. •Vosability limits fo1" ir-etnca 25 audits.
Pr-!)bdliiii..ixIJjiiits in. U3ics
Mean _3G£1P0 90/100 75/100 50/100
Level JL I Bias „ U L U LULU
!Hch ppm C 117 - 62 -41 3? -37 ?6 -?8 16 -If! 7
Lew ppm C 127 16? -66 93 -53 85 -32 64 -12 4<1
481
-------
lable 2. Probability limits for method 18 audits.
Mean
Compounds
. M_
X_'Jl35
Benzene
104
OS!
Carbon tetrachloride
8
Chlorofcrn
11
2%
Ethylene
10
-8%
Hexane
15
-1%
Methyl ethyl ketone
11
HethyTene chloride
14
-
Perch"1 orcptrylene
16
105!
Proprtne
48
-2t
Propy1ene
12
Jo
Toluene
34
¦2%
Trichiorocthvlcne
13
-2%
Viny", chloride
19
-63!
-1. 3- 3jtadiene
11
-3*
°rcDabilitv Limits in % Bias
95/ISO 90/100 75/100 50/100
,l_ JJ L_ JJ I U L_ JJ
16
16
13
13
9
9
5
5
98
98
¦76
76
-49
49
27
28
-6
12
- 4
10
- L
8
0
6
-54
38
-45
29
-32
16
-?2
6
-20
18
-17
lb
-12
9
- 8
b
-107
84
-88
65
-62
40
-40
18
-90
9?
-73
75
-49
50
-28
29
-59
79
-46
6/
-28
'8
-11
32
-19
15
-16
12
¦11
8
7
4
27
20
-22
15
16
9
¦11
4
37
33
-31
27
22
18
14
9
16
11
13
8
-10
5
_ 7
2
-33
2?
-28
17
-21
10
-15
3
-23
:e
-19
12
-i4
7
- 9
•)
-------
ANALYSIS OF PROTOCOL GASES
An On-Going Quality Assurance Audit
Avis P. Hines, Oscar L. Dowler and William J, Mitchell
U.S. Environmental Protection Agency
Atmospheric Research and Exposure Assessment Laboratory
Research Triangle Park, NC 27711
ABSTRACT
In 1992, EPA's Atmospheric Research and Exposure Assessment Laboratory initiated
a nationwide QA program on the suppliers of HPA Protocol Gases, l'hc program has three
goals: to increase the acceptance and use of Protocol Gases by the air monitoring
community, to provide a QA check for the suppliers of these gases, and to help the users of
these gases identify suppliers who can consistently provide accurately certified Protocol
Gases In this QA program which operates continuously, Protocol Gases are procured by
EPA and the supplier's certification of the pollutant concentration(s) is verified by EPA. The
results are published on the EPA Technology Transfer Network's electronic bulletin board.
If a supplier's concentration differs from EPA's by more tlian 2%, the supplier is notified in
writing immediately. The results obtained for SO,. CO and NO Protocol Gases in single and
multiblend mixtures are presented.
INTRODUCTION
The Atmospheric Research and Exposure Assessment Laboratory (ARHAI.) of the
U.S. Environmental Protection Agency (EPA) has begun a nationwide audit of the vendors of
Protocol standards. The intent of this program is as follows:
1. Increase the acceptance and use of Protocol Gases as secondary standards by
the air monitoring community.
2. Provide a quality assurance check for the vendors of
these gases.
3. Assist users of Protocol Gases to identify vendors who can consistently
provide accurately certified Protocol Gases.
PROCKDURK
Either directly or through third parties, EPA procures Protocol Gases from
commercial sources, checks the accuracy of the vendors' certification of concentration, and
examines the accompanying documentation for completeness and accuracy.
483
-------
The Protocol Gas procedure specifies two types of documentation that must
accompany the gas cylinder: a Certificate of Analysis, which may he mailed separately or
attached to the cylinder; and a cylinder tap which must be attached to the valve under the
valve cap. Documentation is incomplete until the vendor provides every item shown in
Tables 1 and 2 for the certificate and the tag, respectively.
Protocol Gases have a maximum allowable deviation of 2% from the certified value.
Accuracy of the certification is checked using Standard Reference Materials (SRMs). If the
difference between the HPA-determined and the vendor-determined concentration is more
than 2%, the Protocol Gas' concentration likely is incorrect. This 2% limit accommodates
the 1 % uncertainly in the concentrations of NTIST gaseous SRMs. In other words if the
difference between EPA's value and a manufacturer's value differs hy 2% or less than
statistically there is no difference between the two values because of the uncertainties in
the total measurement system.
When the difference between the EPA and the Manufacturer's values exceeds 2.0%,
we send the Protocol Gases to a referee laboratory to confirm that this difference is real. If
the referee analysis confirms the El'A results, EPA notifies the vendor of the Protocol Gas to
resolve and correct the problem.
Results of EPA certification checks are placed on two bulletin boards. EMTIC
(Emission Measurement Technology Information Center) and AMTIC (Ambient Monitoring
Technology Information Center), on the Technology Transfer Network of the EPA's Office
of Air Quality Planning and Standards.
Bulletin board entries arc organized in tables by gas mixture and by vendor.
Numerical data are supplemented by narrative footnotes explaining the results of any
corrective action taken by the vendor. Thus the entries provide a continuous record of all
audit activities. The bulletin boards are updated whenever EPA conducts a new audit or
receives corrective action reports from a vendor. It allows users of Protocol Gases to easily
review the comparative performances of the vendors.
Users who believe that their Protocol Gas has been certified incorrectly are
encouraged to contact Ms. Avis Hines of ARF.AL (919 -541-4001) to request an EPA
certification check. If EPA accepts the gas cylinder for testing, the results of these tests will
also be posted on the bulletin boards. If you wish to access the EBB or need information on
how to access the EBB contact Ms. Avis Hines.
RESULTS
Completeness of Documentation
The completeness of the documentation has increased dramatically since this program
was initiated in July 1992, i.e.,
Compile Documentation
July - December 1992 5 of 15 Gases (33%)
January - June 1993 5 of 11 Gases (62%)
July - December 1993 18 of 18 Gases (lOOSi)
-------
Accuracy Checks
Tables 3 and 4 summarize the results from the accuracy checks for single component
and multi component Protocol Gases, respectively. The results are presented by supplier and
by pollutant. The results from the accuracy checks for single component Protocol Gases
have been similar to the completeness of documentation checks, in that the percentage of the
Protocol Gases within the 2% limits has increased for each six month period since July 1992.
The first group of multi component Protocol Gases was checked in November and
December 1993 and the results for these mixtures were disappointing. In five of the 18
mixtures the F.PA-dctermined S02 concentration differed by more than 2% from the supplier-
determined concentration. It has now been determined that in at least four of the five cases
incorrectly certified SRMs caused the difference. Once the suppliers had obtained the correct
certified value for their SRMs, their revised S02 concentrations differed by less than 1 %
from the HPA-determined value.
CONCLUSION
The EPA QA program on the suppliers of Protocol Gases has brought dramatic
improvements in the quality of Protocol Gases and in the completeness of the documentation.
This program has been actively supported by both the users and the suppliers of Protocol
Gases. Suppliers of Protocol Gases have found the program to be an effective external QA
program for them and the users of Protocol Gases have found a data base containing
information that is useful to them when deciding from whom to purchase a Protocol Gas.
Based on these encouraging results and the support of the program from the supplier and user
community, AREAL plans to continue this QA program including expanding it to other
pollutant gases.
DISCLAIMER
The information in this document has been funded wholly by the United States
Environmental Protection Agency. It has been subjected to Agency review and approved for
publication.
REFERENCE
1. U. S. EPA Traceahiliiy Protocol for Assay and Certification of Gaseous
Calibration Standards (Revised September 1993), EPA 600/R03/224. U.S. Environmental
Protection Agency; Research Triangle Park, NC 1993.
48.5
-------
Table 1. Required Documentation for a Certificate of Analysis
Cylinder ID number Reference standard data
Certified concentration Protocol statement
of analyte
Balance gas Gas analyzer ID
Cylinder pressure All analyzer readings
Certificate date Calculations to three
significant figures
Expiration date Name and signature of
analyst
Certification period
(months)
Table 2. Required Documentation for a Cylinder Tag
Cylinder ID number
Certified concentration of analyte
Reference standard data
Balance gas
Cylinder pressure
Certification date
Expiration date
Protocol statement
Laboratory ID
Name and signature of analyst
486
-------
Tabic 3. Summary for Single Component Protocol Gases
Number of Gases Within 2%/Number Checked
Supplier
NO
S02
CO
AGA
1/1
Air Products and
1/1
1/0
1/1
Chemicals
Airco Industrial
1/1
2/2
1/1
Gases
Alphagaz Spec.
1/1
1/1
1/1
Gas. Div.
Matheson Gas
1/1
0/2
1/2
Products
MG Industries Gas
1/1
0/1
1/1
Products
National Specialty
1/1
0/1
1/1
Gases
Scott Marrin Gases
1/1
2/2
1/1
Scott Specialty Gases
1/1
1/1
1/1
487
-------
Table 4. Summary for Multi-blend Protocol Gases
Number of Gases Within 2%/Numbcr Checked
Supplier
SO,
NO
AGA
2/2
2/2
Air Products and
Chemicals
Airco Industrial
1/2
2/2
Gases
Alphagaz Spec.
1/2
1'2
Gas. Div.
Matheson Gas
2/2
2/2
Products
MG Industries Gas
2/2
V2
Products
National Specialty
1/2
2/2
Gases
Scott Marrin Gases
2/2
2/2
Scott Specialty Gases
1/2
VI
488
-------
Preparation and Evaluation of Representative Compounds in Small High
Pressure Cylinders for Use as Audit Materials
by
William Mitchell, Jack Suggs, and Howard Crist
U.S. EPA/AREAL (MD-77B)
Research Triangle Park. NC 27711
and
Ron Bousquet, Ron Brandc, John Duncan, and John Holland
ManTcch F.nvironmcntal Technology Inc.
Research Triangle Park, NC 27709
ABSTRACT
EPA currently regulates or plans to regulate over 130 organic and 20 inorganic gases
as air pollutants. These compounds can be found in air matrices from 1 ppb to 1000 ppm
and in different relative ratios. This presentation describes the evaluation of a gas transfer
system that will allow an organization to prepare a wide variety of QA and (,)(' audit gas
mixtures using a small number of master gas mixtures. It has been used in our laboratory
to prepare over 60 mixtures for use as performance evaluation and audit materials in
support of the KI'A regulations. The gas transfer system uses small, reusable, high pressure
cylinders to prepare custom gas mixtures from large master cylinders. Experiments:
conducted to determine the maximum dilution ralio, and transfer efficiencies of organic
compounds are described. Stability data are presented for compounds that have been
contained in the small cylinders for more than one year. Additional experiments planned
for the future are also described.
INTRODUCTION
Small quantities of certified gas mixtures are often needed by both the regulators and
the regulated to verify the performance of sampling systems, analytical laboratories and
pollution control equipment. To provide gaseous materials that can be used as audit
samples, a gas transfer system (GTS) was assembled and tested.' The system uses static
dilution of concentrated master gas mixtures with a pure diluent or other pollutant mixture
(Figure i) to prepare QA and QC samples in small, reusable, high pressure cylinders. In the
earlier study', which was done to check the integrity of the GTS, no leaks were found and
the GTS was found to be easy to clear, using repetitive evacuation and pressurization with
high purity nitrogen. Ancillary equipment used for performance evaluation studies was also
tested for acceptable performance. No transfer bias due to the gas cylinder regulators was
noticed, and both the audit cylinders and the regulators were easily cleaned after use'.
Since this earlier study was reported, we have prepared over 60 mixtures of volatile
organic compounds. The compounds chosen (Tables 1 and 2) represent a variety of
hydrocarbons, halocar'nons and polar analytes spanning a wide range of molecular weights
and boiling points. They arc representative of the compounds found on target lists
associated with the RCRA, CERCLA (Superfund,) and the Clean Air Act.
489
-------
The GTS prepares certified mixtures in a variety of ways: (1) dilution of a
concentrated mixture with pollutant free nitrogen; (2) mixing the contents of two or more
master cylinders; and (3) injecting neat compounds into an evacuated cylinder and diluting
to the desired levels. The study reported here describes our experiments to determine the
accuracy of the mixing/dilution process, the stability of the compounds as a function of
cylinder pressure, and transfer efficiency of the GTS as a function of compound and
temperature.
GAS TRANSFER (GTS) SYSTEM
Currently, the GTS consists of a stainless steel manifold (Figure 1) containing eight
diaphragm packless valves, one bellows valve, two pressure gauges (0-200 psi and 0-2000
psi) and fittings to attach five compressed gas cylinders.
All internal parts of the manifold have been treated with Scott Specialty Gases'
Acuclean and Aculife processes. The manifold is mounted on a 3.2 mm thick aluminum
plate which is mounted on a wall at Mar.Tech Environmental Technology's Commercial
Park West facility in Research Triangle Park, NC. To maintain a constant temperature, the
GTS manifold is wrapped with hear tape covered with insulation. All tubing-to-tubing and
tubing-to-valve connections are cither orbitallv welded or are of the VCR type.
The manifold can accommodate two master cylinders, a diluent cylinder and two
receiver (audit) cylinders such as the 11 cm o.d. x 25.4 cm long aluminum cylinders we are
now evaluating for use with this gas transfer system. These audit cylinders have been
treated with Scott's Acuclean and Aculife processes and pressure tested to 3000 psi. Their
nominal volume at one atmosphere is 1.5 L, wliich corresponds to 220 L at 2200 psi. They
and the other compressed gas cylinders attach to the manifold using a CGA to VCR
adapter.
EXPERIMENTS TO CHARACTERIZE THE GTS
Analytical System
The GTS can be used for inorganic and organic gas mixtures. Presently, we are
studying only organic mixtures. Two or three samples are taken from each gas mixture
(replicates) and analyzed as discrete samples using either a cryogenic concentrating system
with a 111' 5X90 Series 11/H1' 5970 GO'MSI) system or a GC'MI) system, for the gas
transfer efficiency studies, the GC'MSD system uses the master gas mixture as the
reference standard. For most of the compounds in the gas mixtures being evaluated, the
precision of the GC./MSD system is between 5 and 10% of the concentration and for the
GC/F1D system its less than 5%.
Maximum Dilution Ratio
To maximize the dilution ratio, and increase the accuracy of the system, the original
analog psig gauges were replaced with digital electronic gauges. The original psig gauges
were considered to be accurate to 1 % of full scale. Under the original circumstances the
theoretical maximum dilution was approximately 100 fold. This was based on a diluent
cylinder having a pressure of 2000 psig and the ability to read the analog gauge on the GTS
accurately at 20 psig.
Digital replacements obtained from Omega F'ngineering Inc. are reported by the
company to be accurate to 0.2 per cent of full scale, and capable of reading absolute
pressure. When these gauges are used, the error associated with 5 psia is four per cent.
490
-------
For most organic compounds this would not contribute greatly to lite total analytical error.
Master cylinders containing series A and series B compounds (Tabic 2) at 20 ppm
were diluted on separate occasions using VOC-frce nitrogen. These dilutions required the
operator to slowly fill the evacuated audit cylinders to 1.5 psia of pressure using the
pollutant mix. The diluent nitrogen was then added to a final pressure of 1500 psia.
Recoveries were greater than 90%, as compared to the undiluted cylinders, for all
compounds except acetonitrile and 1,4-dioxane. Only about 70 per cent of the acetonitrile
and even less of the 1,4-dioxane was recovered. The result of tliis experiment demonstrated
that even 1000 fold dilutions may be made accurately and with good recovery for most
compounds studied.
Mixing at Low Concentrations
Another important potential advantage of the GTS is the ability to mix the contents
of a number of master cylinders, even at low concentrations. The master cylinders
containing series A and series B compounds (Tabic 2) at 20 ppb were used to evaluate this
teelmique. Two hundred and fifty psia of each master cylinder were added to duplicate
audit cylinders and the mixtures were analyzed using the system described previously.
Mean hydrocarbon recoveries were all greater than 90 per cent except for stvrene
which was 81 per cent. I [alocarhon recoveries were greater than 90 per cent except for
1,2-dibromoethane which was 89 per cent. The polar analytes were recovered at less than
50 per cent. While overall the results were favorable, some of the analytes demonstrated
marginal recoveries under these conditions when compared to the experiment which
evaluated the maximum dilution ratio. (In the latter experiment, which used more
concentrated materials, stvrene and 1,2-dibromoethane demonstrated recoveries close to 100
per cent.) When the former experiment was repeated after modifying the heated zones to
include the transfer lines from the master cylinder to the GTS and also the small cylinder
valve and associated connection, recoveries of stvrene and 1,2-dibromocthane improved to
greater than 95 per cent.
Stability Tests
In March of 1993 a gas mixture was prepared by mixing three volumes of a gas
mixture containing 20 aromatic and halogenated compounds at 5-10 ppb with one volume
of another mixture containing 9 unique alkane compounds at 20 ppb. The resulting 800 psi
mixture was re-analyzed after 379 days. Twenty one of the twenty nine compounds were
within 10 per cent of their original value and Twenty four were within 20 per cent of their
original value. Bromoinelhane, 1,2-dibromoethane and styrene were not detected. Ortho
xylene and chlorobcnzcnc were detected at 69 % and 72 % of their original value. In a
separate experiment we investigated the effect of decreased cylinder pressure on stability.
Two cylinders were originally pressurized to 1300 psi with 33 C2-C10 hydrocarbons at 45
ppb v. After forty one days the pressure was reduced in one of the cylinders to 650 psi.
After more than 300 days under these conditions, 31 of the compounds demonstrated less
than a 10 % difference in concentration between the two cylinders. For the other two
compounds: acetylene differed by 20 % between the cylinders and 1,2,4-trimethylbenzene
differed by 11 %.
Transfer Efficiency Tests
Quantitative transfer out of the cylinder and into the measurement system was also
evaluated using field data from two intercomparison studies supporting El'A's
Photochemical Assessment Monitoring Network (PAMS). Jn these intercomparison studies
491
-------
the participants received audit cylinders containing l'AMS target analytes which they
analyzed with their PAMS measurement analytical system. Their analytical results indicate
that the analytical conditions are important for full recovery of heavier compounds. For
example, the mean per cent recovery of the higher molecular weight compounds was 5 to
10 % greater for those participants who transferred the gas from the audit cylinder into a
humidified canister before introducing the sample into their analytical system tlian for those
that who went directly from the cylinder to the analytical system. Because the reliable data
sets are small, no statistical tests were applied to these data.
Our laboratory experiments have demonstrated that the difference between recoveries
is not dependent on transfer out of the cylinder. The analvte is most likely lost in cold
spots, dead volumes or other forms of active sites in the transfer lines to the measurement
system. In this experiment, humidified canisters were prepared from the small audit
cylinders by transferring the contents of the audit cylinder to the canister with a short
length of 1/8 inch i.d. stainless steel tubing. The transfer took place over fifteen minutes
and no flow control was used. The final pressure in the canister was about 30 psia and the
relative humidity was approximately 50 per cent.
For ethyl benzene and other heavier compounds, recoveries were up to 40 per cent
greater from the canisters than from the audit cylinders, and within 10 per cent of the
theoretical value. This effect was only apparent on some analytical systems. Since the
canisters were prepared directly from the small cylinders, near complete transfer must be
taking place. A humid sample may overcome active sites in the measurement system to
some extent.
CONCLUSIONS
After one year of use the GTS has proven to be a reliable method of preparing
gaseous pollutant audit materials. Gases from stock cylinders containing binary or
multicomponent mixtures may be diluted and mixed over a wide range of concentrations.
Over 60 audit mixtures have been prepared and used in the field. Contamination of the
GTS, cylinders and regulators has not been a problem and routine audits, using this system,
have been scheduled for one program. Many hydrocarbon and halocarbon compounds have
proven to be stable at the ppb level even after one year in the cylinder.
Due to improvements made to the original system, recovery for most compounds has
increased to 95 per cent. Dilutions as high as 1000 fold are accurate to within 10 per cent
and the mean per cent recovery for most compounds other than those that arc polar has
been greater than 90 per cent.
Using the GTS, organizations can prepare at relatively low cost a myriad of gas
mixtures using a small number of master gas mixtures ($200-$ 10,000 each), a diluent gas
($50-5250 each) and reusable compressed gas cylinders (S300-S450 each). The GTS
should be particularly useful when assessing emission control device performance. It
should also be very useful for gas mixtures whose long-term stability is known only for
concentrations 10 to 100 times higher than those needed for the measurement systems.
FUTURE WORK
Additional plans und experiments include the addition of a six port manifold to the
system to increase the number of replicates produced. Direct liquid injections into the
492
-------
cylinder, followed by the addition of diluent gas will be investigated and further
characterization will help answer questions concerning the stability and recovery of problem
compounds. More attention will be focused on methods of delivering the sample to the
measurement system and vendor cylinder treatment processes will be evaluated.
REFERENCES
). Mitchell,W.,Streib.E.,Crist,H.,et al., "A Low Cost Procedure to Make Gaseous
Pollutant Audit Materials", in Proceedings of the 1993 U.S. EPA/A&WMA International
¦Symposium on Measurement of Toxic and Related Air Pollutants.VIP-34: Air & Waste
Management Association; Pittsburgh, 1993; pp 363-369.
DISCLAIMER
The information in this document has been funded wholly by the United States
Environmental Protection Agency. It has been subjected to Agency review and approved
for publication. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
Table 1. Representative compounds used to evaluate the GTS.
Hydrocarbons
Halocarbons
Polars
Ethane
Vinyl Chloride
Acetonitrile
Ethylene
Freon 11
Vinyl Acetate
Propylene
Methylene Chloride
1,4-Dioxane
Propane
1,2-Dichloropropane
Hexane
Trichlorocthylene
1,3-Butadiene
Chlorobenzene
Toluene
1,1-Dichloroethene
Cyclohexane
Chloroform
p-Xylene
1.2-Dichlroethane
Slyrene
T richloroethy lene
Benzene
1,2-Dibromoethane
Tetrachloroethylcne
Carbon Tetrachloride
493
-------
Table 2. Description of series A and B compounds.
Series A Compounds
Series B Compounds
Acetonitrile
Benzene
Benzene
1,3-Butadiene
Carbon Tetrachloride
Chloroform
Chlorobenzene
1,2-Dibrornoethane
1,2-Dichloropropanc
1.2-Dichloroethanc
I Ethylene
1,1-DichIoroethene
Halocarbon 11
1.4-Dioxane
n-Hexane
Ethane
Methylene Chloride
N-Hexane
Propane
Propylene
Slyrcne
T etrachloroethv lene
Toluene
Trichloroethylene
Trichloroethylene
Vinyl Acetate
Vinyl Chloride
p-Xylene
p-Xylene
Cyclohexanc
494
-------
Sfpl
FIGCJRK 1. Cas transfer system.
495
-------
DATA HANDLING ISSUICS AN1) TECHNIQUES ASSOCIATED WITH DATA
COLLECTED FROM AUTOMATED GC SYSTEMS USED FOR OZONE
PRECURSOR ANALYSIS
Larry D. Ogle. Margaret A. Underwood. Pamela R. Chen,
Pat G. Edwards, Walt L. Crow and Rebecca H. Burris
Radian Corporation
8501 North Mopac Hlvd.
P.O. Box 2010X8
Austin, Texas 78720-1088
Jim Price and John Gibich
Texas Natural Resources Conservation Commission
P.O. Box 13087
Austin, Texas 7H711-307X
Paul Radenheimer
Consolidated Sciences Incorporated
141ft Southmore
Pasadena, Texas 77502
ABSTRACT
The 55 compounds designated by the U. S. Environmental Protection Agency as ozone precursors were
monitored in the ambient uir in Houston. Texas, from June 18 to November 30, 1993. Two Perkin-Elmer automal
continuous gas chromatographic (GC) systems were used to monitor these compounds or. an hourly basis throughc
the day. A total of 4X data files were collected at each site daily. In addition, method, sequence, and the electron
logbook files were transferred from each site daily in order to process the data. Numerous data handling techniqu
were developed to process, verify, validate and transfer to the database the two to three Megabytes of data general
This paper will describe the techniques and tools developed to process such a volume ol data in a cost and rime
effective manner.
INTRODUCTION
Two sites in Houston, Texas were selected for deployment of Perkln-Elracr continuous GC systems for th
hourly measurement of the 55 ozone precursor compounds. This effort was a portion of the Texas Natural Resou
Conservation Commission (TNKCC) Coastal Oxidant Assessment for Southeast Texas (COAST) study. The obje
of the COAST study was to improve the technical basis for designing effective ozone control strategies for the
southeast Texas coast area (including Houston), lite Clinton Drive site oil the east side oi Houston was selected
to tlie number of petrochemical industry sources in the vicinity and to aid in the assessment of the impact of
hydrocarbon emissions from these sources on ozone formation. A second site, designated the Galleria sire, was c
west side of Houston and represented a major vehicular traffic impact area, but contained little contribution from
industry sources. A general overview of die continuous GC systems and the COAST project is provided in a
companion paper.'
The Perkin-Elmer Continuous GC systems are designed for unattended 24 hour operation. Each systems
utilizes dual columns and dual Flame Ionization Detectors (FID) to separate and detect the compounds of interest
Due to the differences in compounds detected, each detector requires separate calibration, processing and sequent
methods. Therefore, two sets of methods are required for each analyzer. A total of 4S data files are produced e;
day with 96 data files for two sites. Since both raw and processed files are produced, a grand total ot 192 data 1
are generated daily. Combined with the method files, sequence files and electronic logbook files required to rep
496
-------
dam, two to three Megabytes of data is transferred daily from the field to Austin. Field operations and the data
transfer procedures have been described in other papers.2,3
Manual review of each of the chromatograms and data files produced each day is virtually impossible given
the time and financial restraints which would result. Therefore, a number of tools were developed to quickly and
¦ifficiently review the data, compound identifications and concentrations, presence of outliers and proper instrument
jperation. tn addition, it was desirable to quickly communicate problems with the analysis, quantitation or
dentification to the field operators for correction.
RESULTS AND DISCUSSION
Original instrument, calibration, method and electronic logbook files were electronically maintained on hard
iisk at the sites and on Bernoulli disks at the Consolidated Sciences offices. Data was automatically retrieved from
he, field sites each morning and transfe,rred to a local host computer system ai Consolidated Sciences as shown in the
lata (low schematic, Hgurc I. These files were then compressed and automatically transferred via high speed modem
,nd PC Anywhere software to Radian's Austin office. At times, problems were observed with the automated transfer
•f the data to Radian as evidenced by incomplete files or error messages. Many of these problems were attributed to
:ic quality of the long distance telephone lines. When these problems were observed, Consolidated Sciences was
ontacted directly and the data was retransmitted manually.
Upon receipt of the compressed files at Radian, they were expanded, the processed data files from the two
olumns at each site were combined and the data were loaded into Radian's Oracle database. Quick]ook reports were
enerated which consisted of:
• A report of the non-nieUiane organic carbon (NMOC) and unidentified compounds (UNIDVOC) for
each hour of the day;
A calibration check and blank report for that day.
The minimum, maximum, average and standard deviation for each of the target analytcs for that day;
and,
• Measured values for every compound at each hour of that day.
These files were used for primary review of the raw data. Data were screened for missing hourly files,
issing compounds, apparent misidentifications, unusually high concentrations, or any data that generally looked
spicious. Data files wliich contained any of these items were marked for further investigation in the initial data
rification.
Hies wliich were determined from the Quicklook reports to have errors or suspicious data initiated a review of
; possible causes. Electronic log entries were reviewed to determine if instrument problems, down-time or
viatioas from scheduled sample collections are noted. Missing data files not addressed in the logs were retrieved
mi the host computer or from back-up disks. Held personnel were contacted to confirm missing data files, as
cessary. Calibration logs were used to detail the installation of standards at the sites and provide theoretical
ncentrations of the standards' components. Method logs were screened to address modifications made to the data
icessing methods at the sites and to determine when response factors were updated.
Obvious data problems such as misidentifications or missed target analytes due to retention time drift were
ved by adjustments to the appropriate methods and batch reprocessing the data using the Perkin-F.lmer
rbochromc soltware. Other problems were also noted such as UNIDVOC concentrations greater than 20() ppbC
ich typically indicated the presence of an electronic spike unless the associated NMOC was also very high. The
¦omatograms were reviewed for spikes and, if found, the data were qualified accordingly. Problems observed in the
a could quickly be communicated to field personnel so corrective action could be taken at the sites, reducing the
;d for post-processing.
497
-------
Compound concentrations were checked against the monthly cumulative averages. An hourly summary repo:
which lists the concentrations of the oionc precursors over tils 24 hour period for that day was checked for data
reasonableness. Based on a solid knowledge of typical ambient air patterns and concentrations, the (lata validator
reviewed data trends (e.g. conformity to traffic patterns), relative isomer ratios and concentrations, missing or
atypically low concentrations for compounds ubiquitous, in Houston ambient air (wliicli may indicate sample shifting
or misidentifications), and data outliers. Individual files containing questionable values were marked and the
corresponding cliromatograms were reviewed for accurate peak assignments and integrations. U the peak assigiuneii'
and quantitation appeared to he correct, that observation was documented on the summary report. Otherwise, the da
files were manually reprocessed or Uie data were later qualified. Daily averages summary reports which list the
minimum, maximum, and average concentrations of each of the ozone precursors over a 24-hour period were also
reviewed as an aid in identifying outliers.
As an illustration of the. process, the NMOC and IJN1DVOC concentrations of the data collected at the Clin
site on October 6th (Figure 2) were reviewed for anomalies. The NMOC concentrations for huure 20-23 appeared
relatively high in relation to hours 01-19, especially after allowing for reduced traffic anticipated in the late evening
hours. The UNIDVOC concentration appeared reasonable, suggesting thar the high NMOC concentrations were not
due to the presence of electronic spikes or system contaminants (unless interference with target analytes resulted).
Review of the daily averages summary report (Figure 3) revealed extremely high levels of toluene during the ?4-ho
monitoring period. Review of the hourly summary report ( a partial report is shown in figure 4) confirmed
uncharacteristically high toluene concentrations during hours 20-23 which did not follow the typical concentration
pattern. The individual report and chromatographic files were examined and presence of toluene and the reported
concentrations were confirmed (Figure 5). A note was made of this confirmation and forwarded to the senior cheir
performing the final data validation to assist in tlieir review/evaluation of the data.
In addition to the problem/suspected anomalous files, approximately 5% of the field processed data
files/chromatograms were visually checked for accuracy of peak identifications, baseline integrations, peak resolutk
baseline noise and drift, and the presence of system contaminants and spikes. Review of multiple files acquired o\
2-3 week period assisted in determining the magnitude and extent of retention time shifting. Method modifications
such as retention time window adjustments and baseline integrations, were tested on a subset of data files to ensua
accuracy of peak assignments and quantitation. The data files were then batch-reprocessed with the optimized
methods. The reprocessed data was then loaded into the database. Reprocessed files were placed in a designated
directory which indicated the date of revision and revision number. All raw data and revisions of the data were
archived for reference. Revised daily calibration and Quicklook summary reports were again generated for data re
Revised calibration and sample data summary reports were reviewed in-depth for accuracy. Data validatio
comments made during the data review process were documented and filed with hard copies of the daily sample d
summary reports. The comments were also used to prepare data qualification statements for the final report. All
revised reports were validated by a senioi chemist familiar Willi Houston ambient air patterns, compounds and
compound concentratioas. Any anomalies noted by this chemist were referred lo die verification/reprocessing dat<
analyst for further review of chromatograius and reports. Final revisions and/or data qualifiers were added and thi
revised data were loaded into the database. A final data validation for accuracy was preformed and the data were
reported to the COAST Program Management Contractor (Desert Research institute) in a format specified for thci
database. Reports in AIRS format can also be provided.
CONCLUSIONS
Development of data handling techniques, such as the Quicklook reports, have resulted in efficient and co
effective means for handling large amounts ol data generated trom continuous monitoring field instrumentation. '
tools developed provided tecliniques to quickly review, reprocess and report high quality data wid\ a minimum of
analyst interaction. In addition, it was possible to provide timely feedback to field operators so that problems wit
instrumentation or methods could be corrected to reduce the amount of post-collection processing needed. The u:
these techniques also aided in meeting all project quality control requirements for continuing calibration check sa
and audit samples. Data capture for the overall project was very good with 94% data capture from the Clinton C
site and 95% data capture from the Gallcria site.
498
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REFERENCES
. J. Gibich, I.. Ogle and P. Racicnhsimcr. "Analysis of Ozone Precursor Compounds in Houston, Texas, '-"sing
Vutomatcd, Continuous Gas Chroinalograplis". Prepared lor presentation at the International Symposium on the
.leasurement of Toxic ami Related Air Pollutants, May 3-6, 1994, Durham, NC.
V. Radenheimer.). Gibich and L. Ogle, "Tlie Perkin Blmer ATD-400 System for Monitoring of Ambient VOC
Jzone Precursors", Prepared for presentation at the International Symposium on the Measurement of Toxic and
delated Air Pollutants, May 3-6, 1994, Durham, NC.
.. P. Radenheimer, J. Gihich and L. Ogle, "System Operation: Continuous Volatile Organic Compound Air
-lonitoring of 56 Ozone Precursor with the Pcrkin-Elmer 8700 anil Automatic Thermal Dcsorptiou System", Prepared
i>r presentation at tlie International Syuiposium on liic Measurement of Toxic and Related Air Pollutants, May 3-6,
994, Durham, NC.
File Transfer
Errors
Data Validation |
Data Reported
TNRCC
Data Review
Verification
Quicklook
Reports
Data
Processing
Data Review
Senior Chemist
Radian Database
(Processed Files)
Radian Operating
System
Field Sites
Data Acquisition
and Processing
Consolidated
Sciences
Hub Computer
Figure 1. Data Flow Schematic
499
-------
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Figure 5. Chromatogram of Suspect Toluene
-------
A Computer Controlled Dynamic Dilution System for Improved Accuracy
and QA/QC in T014 Standard Preparation
I).II. Cardin andJ.T. Deschenes
Entcch Laboratory Automation
950 Enchanted Way #101
Simi Valley, CA 93065
Dynamic Dilution is the method of choice for preparing low level TO 14
standards in canisters. One or more cylinders containing NIST certified standards can
be blended together with a diluent gas under mass flow control to pioduce very
consistent standards at ppb levels. Blending manifolds can be designed to maintain
constant temperatures, pressures, and flow rates during the entire canister filling
operation to insure that a proper mass balance- is maintained.
One major source of error can exist when using Dynamic Dilution that can be
significant in some cases. Manufacturers of mass flow controllers usually specify an
absolute error of not more than +2% of the full scale flow rate. This means that
MFC's rated up to KM) seem (standard cc per minute) could be off as much as 2 cc.
At 100% of full scale, this results in an unfortunate but tolerable error of ±2%.
However, at 10% of full scale, a 2cc error corresponds to a 20% relative error which
is not acceptable. Avaflable dynamic dilution systems have been unable to perfuun
automatic calibrations of mass flow controllers to account and correct for these
inaccuracies.
A Dynamic Dilution system is presented that interfaces to a Windows™-based
operating system allowing implementation of sophisticated flow calculations and
feedback control. The dilution system is capable of using temperatuie compensated
vacuum reservoir prcssurization to calibrate up to 6 MFC channels unattended.
Multiple calibration events can be set up to run sequentially with Means and "IKSDs
given for the data obtained for improved reliability. Calibrations over a several day
period show the stability of mass flow controllers and can indicate the presence of
unusually large drifts. These calibration factors arc then used by the dilution system
to make collections in flow signals to provide very accurate ppb level standaids. The
preparation of multiple standards in different canisters without user intervention is also
supported for making 2, 5. 10, 20, and 50 ppb level standards for TOI4 instrument
calibration.
-------
Importance of Method Detection Limits
in Air Pollutant Measurements
Nancy H. Adams
US I;PA, Air and hnergy Engineering Research Laboratory,
MD-49
Research Triangle Park, NC 27711
ABSTRACT
Environmental measurements often produce many "less than" values or method detection limits
(MDLs). MDL values may be used in determining compliance with regulatory limits, in the
determination of emission factors (typical concentrations emitted by a given type of source), or in
modeling efforts that feed into air measurement data bases. There is considerable technical discussion
regarding definitions of, and methods for determining, detection limits. The definition and determination
of MDLs are therefore important in planning an environmental measurement program After an
appropriate MDL has been determined, there are several ways to use the MDL value to calculate the
mean concentration from a low level source. To avoid introducing high or low biases in the calculated
mean, this paper proposes the use. of look-up tables to fill in missing (less than MDL) values with
statistically based estimates.
There are many approaches to dealing with the MDL issue, and the approach selected should
depend on the end-use of the data. The MDL should be determined in the matrix that contains the
analyte. Methods to calculate the MDL should be specified before the initiation of a measurement effort.
INTRODUCTION
An expanded understanding of the toxic effects of chronic low level exposure to air pollutants,
regulatory- mandates to improve workplace safety, and public pressure to eliminate all exposures to
carcinogens have all focused attention on the need for accurate low level measurements of toxic materials
in the air. These low level measurements often border on the limits of a measurement instrument's
capability to detect the pollutant of interest. There have been technical discussions regarding how to
define the detection limit, how to experimentally determine the detection limit, and how to use the
detection limit values in subsequent calculations. This paper presents a brief overview of some current
issues related to detection limits.
The manufacturer's stated MDL for a measurement instrument is frequently used as the estimated
MDL, but tliis MDL is almost always loo low. The manufacturer's MDL is oflen obtained experimentally
under ideal conditions in a matrix such as zero air with minimal interferences. A more accurate MDL can
be obtained by using a "real world" matrix that approximates the measured matrix Accuracy of the MDL
estimate is also improved by perfoiming multiple determinations using the same laboratory personnel and
instrumentation that will be used in the measurement project.
DEFINITIONS RELATING TO DETECTION LIMIT
Several definitions of the detection limit have been proposed by regulatory and professional
groups. Concurrently, these groups have also proposed definitions and methods for determining the level
of an analyte that can reliably be reported as an accurate number (quantitative detection limit). The
following definitions appear frequently in the literature relating to detection limits:
Method detection limit (MDL) - The MDL is defined in the Code of Federal Regulations (CFR)
(1) as "the minimum concentration of a substance that can be measured and reported with 99%
-------
confidence that the analytc concentration is greater than zero." The MDL is calculated as the
experimentally determined standard deviation, or s, times the Student's t-value for a 99% confidence
level. This Student's t-value is approximately 3 for an experimental design with seven replicates.
Limit of detection (LOD) - The LOD is a term used by the American Chemical Society (ACS) (2)
to describe the lowest concentration that can be determined to be statistically different from a blank The
LOD is generally equivalent to the MDL, although the limits of statistical probability can vary (e.g , 95%
rather than 99%)
Limit of quantitation (LOQ) - The L.OQ, as defined by the ACS, is the smallest true concentration
where a single measurement used to estimate the unknown concentration in a sample would have an
estimation error no greater than +30% with 99% confidence (2). The LOQ, generally set at 10s, is the
concentration level at which the analyst has some measure of confidence that the analyte is present and
that the reported value is accurate.
Minimum level (ML) - The ML is the level at which an analytical system must give a recognizable
signal and an acceptable calibration point (3). An ML is generally set at 10 or 12s and is rounded off to
the nearest multiple of 2, 5, 10, 20, 50, or 100 to simplify the preparation of calibration standards.
Practical quantitation limit (PQL) - The PQL is the lowest level that can be reliably achieved
within specified limits of precision and accuracy during routine laboratory operations (4). The PQT. is
generally greater than or equal to the LOQ and the ML. A recent paper advocated that no quantitative
regulatory data be required below the PQL (5).
Detection Limits with Specified Assurance Probabilities - Several recent papers (6, 7, 8) describe
statistical methods for determining detection limits using all of the calibration data and data from replicate
analyses. Detection limits determined using these methods are dependent on the number of replicate
analyses and the calibration design Acceptable false negative and false positive rates are specified
These methods require the use of computer-assisted statistical packages and statistical expertise or the
assistance of a statistician with knowledge of both the statistical methods and the teclmical limitations of
the measurement technology. A description of these methods is beyond the scope of this paper.
In summary, four basic concepts relate to the determination of detection limits:
• The MDL and LOD describe the lowest level at which an analytc can reliably be differentiated
from background noise The MDL and LOD are generally equivalent, and both are generally set
at 3 s
• The ML and LOQ describe that concentiation at which reliable quantitative information can be
obtained. The ML and LOQ are generally set at 10s.
• The PQL also describes a level aT which reliable quantitative data can be obtained, but the PQL
may be set at levels greater than the LOQ or ML.
• More rigorous statistical methods have been described that use all of the calibration and replicate
analysis data To estimate a detection limit with acceptable false positive and false negative rates.
40CKK I'ROCRIH'RK FOR DETERMINING THE MDI,
The method for determining the MDL as described in the 40CFR136 (1) serves as a model for the
laboratory determination of detection limits. It contains many useful concepts that can be applied to the
other methods described above The OR method contains the following steps:
501
-------
1) The MDL should be determined in the same matrix as that which contains the analyte of interest
Different matrices can make significant differences in the level of an analyte that can be detected by a
given method*.
2) The MDL is estimated as: (a) 2.5 to 5.0 times the noise level of a signal when a reagent blank is
analyzed, (b) three limes the standard deviation of replicate measurements of a reagent blank, (c) the
region of a calibration curve where there is a significant change in the standard deviation of replicates, or
(d) known measurement instrument limitations. Use of available information can reduce the time and
effort required to obtain reliable MDL data.
3) The MDL is then determined experiment ally by replicate analysis of seven aliquots of a sample
containing a level of analyte equal to the estimated MDL Since the variance of replicate measurements
can differ with concentration, it is important to determine variance at a concentration near the
concentration of interest (i.e., near the MDL). The use of seven replicates allows for a more accurate
estimate of this variance.
4) The MDL is calculated as the standard deviation (s) of the seven replicate measurement values times
the Student's t-value for a 99% confidence level at fi degrees of freedom.
5) The OR method also contains an optional iterative procedure to test the validity of the MDL
determination. This procedure involves spiking the appropriate matrix with the analyte of interest at the
initially determined MDL, repeating the seven replicate measurements, and calculating the variance (s1) of
the second set of replicates. An F-ratio (the larger variance value divided by the smaller variance value)
is calculated. If the F-ratio is less than 3.05, the revised standard deviation is then calculated as the
pooled standard deviation of the two experimentally determined standard deviations If the F-ratio is
greater than 3.05, the procedure is reiterated with a new sample set spiked at the most recently calculated
MDL. Some regulatory groups require this iterative procedure. It provides a greater degree of
confidence that the MDL mine is correct.
6) If the most recently calculated MDL does not yield a signal of sufficient intensity for quantitation, then
the revised MDI. is reported as a value halfway between the current and the previously calculated
MDLs
CHARACTERIZING LOW LEVEL SOURCES
One important use of detection limit data is in the characterization of low level sources. This
situation is encountered frequently in measurements of environmental pollutants from ambient air
samples. If, for instance, one wished to calculate a mean level of a pollutant from a given area, there
might be several measurable values and several values that were below the MDL. Methods to estimate
the mean value include:
• Discarding the values that are less than the MDL. This leads to a false positive
bias in the calculated mean.
• Counting the ''MDL values as zero 'litisproduces an artificially low mean.
• Setting the the authors Ciirunerts.
505
-------
Setting the <\1D1. values at half of the MDL. The effect on the calculated mean is
unknown, hut this procedure probably gives a better estimate of the mean than the
first three mentioned above.
Using numerical methods for the statistical calculation of the mean This method
yields the most accurate estimate of the mean; however, it is beyond the capability
of most chemical analysts, requiring considerable computing power and statistical
expertise.
• Estimating the mean using look-up tables thai replace the
-------
REFERENCES
1. 40CFR, Part 136, Appendix B, 1993, 565-567
2. ACS Committee on Environmental Improvement, Subcommittee on Environmental Analytical
Chemistry, Analytical Chemistry 1980 52, 2242-2249
3. 40CFR, Part 136, Appendix A, Methods 1624 and 1625, 1993, 530-564
4. 50FR, No. 219, November 13, 1985, 46906-46907.
5. Stanko, G.H.. Krochta, W.G., Stanley, A , el al, Environmental Lab Oct/Nov 1993. 16-20 and
60
6. Clayton, C.A., Hines, J W , and Elkins, I' D , Analytical Chemistry 1987 58, 2506-2514.
7. Hubaux, A and Vos, G., .Analytical Chemistry 1970 42, 849-855.
8. Gibbons, R D , Jarke, F.H, and Stoub, K P "Detection Limits: For Linear Calibration Curves
with Increasing Variance and Multiple Future Detection Decisions," in Proceedings of the Fifth
Annual U.S. EPA Symposium on Solid Waste. Testing and Quality Assurance-, U.S. Government
Printing Office, Washington, D C., 1989, 377-390.
9. Dixon, W.J., Annals of Mathematical Statistics 1960 31_, 385-391.
10 Gupta, A K , Biometrika 1952 39, 260-273.
11 Schneider, Helmut, Truncated and Censored Samples from Normal Populations, Marcel Dekker:
New York, 1986; pp 57-126
12. Harter, H.L. and Moore, A.H., Biomctrika 1966 53, 205-213.
13 Leadbetter, M.R., University of North Carolina, Chapel Hill, NC, personal communication,
1994
507
-------
Stability Evaluation of Multicomponent EPA Protocol Gases
Richard C. Shores, Michael J. Messner, and Robert W. Murdoch
Center for Environmental Measurements and Quality Assurance
Research Triangle Institute
Research Triangle Park, NC 27709
Kaster A. Coppedge, Thomas J. Logan, and M. R. Midgett
Atmospheric Research and Exposure Assessment laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
ABSTRACT
An assessment of specialty gas manufacturers' protocol gases was conducted by Research Triangle
Institute (RT1) for the. U.S. Environ mental Protection Agency's (EPA's) Atmospheric Research and Exposure
Assessment I-aboratory (ARF.AL) in 1991 to evaluate the accuracy of ihe manufacturers' reported
concentrations for multicomponent cylinder gases in wo concentration ranges. The cylinders evaluated during
this study were purchased from nine different manufacturers. Two cylinders were purchased from each
manufacturer and contained both SO, and NO v-iih a balance gas of nitrogen. Half of the cylinders contained
SO, at 1500 ppm and NO at 900 ppm and the remaining cylinders contained SO-, at 300 pprr, and NO at 400
ppm.
These same cylinders remained in the custody of RTI after Ihe audit and have been reanalyzed to
evaluate the stability of multicomponent protocol gases over a twn-ycar period. The results of this reanatysis
were within ±2% of the 1991 analysis for all cylinders. No single manufacturer was found different from the
others.
The stability of multicomponent cylinder gases is important hccausc the EPA traceability protocol for
certification of calibration standards specifies recertification intervals for gaseous standards. This paper
presents the results of evaluating the extent to which the concentrations of multicomponent cylinder gases
change over a two year period. This paper also examines how much of a change would be required in order
for it to be detected with statistical confidence.
INTRODUCTION
The U.S. Environmental Protection Agency (EPA) has established quality assurance procedures for air
pollution measurement systems that are intended to reduce the uncertainty in environmental measurements.
One area of concern is the reliability of compressed gas standards used for calibration and audits of continuous
emission monitoring systems. EPA's regulations require that the certified values for these standards be
traceable to National Institute of Standards and Technology (NIST) Standard Reference Materials (SRMs) or to
NlST/EPA-approved Certified Reference Materials via a traceability protocol.1*5 The protocol was published
originally in 1978 and revised several times, with the most recent release in the fall of 1993.
An accuracy assessment of specialty gas manufacturers' protocol gases was conducted by Research
Triangle Institute (RTI) for the EPA's Atmospheric Research and Exposure Assessment laboratory (AREA!.)
in 1991 to evaluate the accuracy of the manufacturers' reported concentrations for muhicomporcnt cylinder
gases.fi Two cylinders were purchased from each of nine different manufacturers and contained both SOj and
NO with a balance gas of nitrogen. Half of the cylinders contained SO, at 1500 ppm and NO at 900 ppm and
the remaining cylinders contained S02 at 300 ppm and NO at 400 ppm. Because this was the eighth
assessment of protocol gas accuracy, this work was referred to as "Cylinder Audit No. 8." The results of
Cylinder Audit No. 8 were presented to the Air and Waste Management Association (AWMA) conference, in
May 1992.
The stability of multicomponent cylinder gases is important because the EPA traceability protocol for
certification of calibration standards specifies recertification intervals for gaseous standards. The 1991
508
-------
protocol procedure specified a 6-month recertification inlerval for mullicomponcnl cylinder gases. Because
this lime interval was not practical for field operations, it was decided to evaluate the stability of
multicomponcnt cylinder gases, This paper presents the results of evaluating the extent to which the
concentrations of multicomponent cylinder gases change over a two-year period. This paper also examines
how much of a change would be required in order for it to be detected with statistical confidence.
ANALYTICAL PROCEDURES
The cylinders were grouped according to their reported concentration (high and low), and the cylinder
contents were analyzed by group. RTI measured the pollutant concentrations of the compressed gas standards
by using instrumental monitors (lMs), ultraviolet fluorescence for S02, and chcmilumincsccncc for NO. Both
calibration standards (NIST SRMs) and compressed gas standards were sampled without dilution through a
stainless steel, Teflon, and glass sampling manifold. Sample flow through (he manifold was controlled by
stainless steel solenoid valves, a needle valve, and a digital timer Row through the manifold remained
constant during both IM calibration and cylinder audit analysis by maintaining a constant manifold pressure
using the compressed gas cylinder regulator as indicated by a Heisc gauge, Ilie sample manifold allowed both
the S02 and NO FMs to analyse cylinder gases simultaneously. Excess cylinder gas was vented from the
laboratory through appropriate exhaust vents. The voltage outputs from the instruments were recorded hy a
data logger. Concentration calculations were made with averaged voltages from the data logger.
Multipoint calibrations were conducted with NIST SRMs. Linearity of the instruments' response was
evaluated by using the multipoint calibration data. During analysis, the concentration of each cylinder gas was
measured three times. Before and after each cylinder gas analysis, NIST SO-, and NO SRMs were sampled by
both the SO, and NO IMs. This routine provided data on the IM stability both before and after the cylinder
gas analysis. Concentrations were calculated as specified by the F.PA protocol procedure.1 This procedure
ratios the NIST SRM to its response when sampling the cylinder's contents.
The NIST SRMs were also used to determine if the presence of SO, affected the response of the NO
IM or if the presence, of NO affected the response of the SO-, IM. This interference lest was necessary
because the NIST S02 and NO SRMs are single-component (i.e., SO, or NO in N,) gases and the cylinder
gas being analyzed contained both S02 and NO in N,. The JMs were first calibrated with single-component
NIST-SRMs, and then (he interference response was tested by blending the SO, and NO NIST SRMs,
generating a multicomponcnt gas.
ACCURACY ASSESSMENT SUMMARY
The accuracy of a manufacturer's certified concentration is defined as the peicent difference between
the manufacturer's certified concentration and RTTs corresponding mean measured concentration. Figure 1 is a
graphical representation of these percent differences. The a%'cragc differences for S02 were 0.8 and 1.5% with
associated standard deviations of the differences of 2.8 and 3.7% for the 300 ppm and 1500-ppm
concentrations, respectively. The average differences for NO were 0.2 and 0.3% with associated standard
deviations of the differences of 1.0 and 1.4% for the 400-ppm and 900-ppm concentrations, respectively. In
general. 72% of the results fell within the ±2% range, and 94% of the results fell within the ±5% range.
UNCERTAINTY ESTIMATES IN ACCURACY ASSESSMENT RESULTS
In estimating the uncertainty in the compressed gas cylinder concentrations that were determined
during Cylinder Audit No. 8, several sources of error, both random and systematic, were considered:
• Uncertainty in the NIST SRMs.
• Error in measuring the effect of NO presence on the S02 measurements.
• Lack of linearity of the IMs.
Memory effects of the iMs and uncertainty in correcting for these effects.
• Variability in repealed measurements on the same cylinder gas.
The results from Cylinder Audit No. 8 concluded that the first four sources of uncertainty combined to
an estimated total of less than 2% at a 95% confidence level. The estimated relative standard deviation was
less than 1%. The fifth source of uncertainty, repeated measurements of the same cylinder, is negligible
because the relative standard deviation was less than 0.2% in each case. This 2% uncertainty estimate dictates
that a difference greater than 2% between the audit concentration and the manufacturer's reported concentration
509
-------
should be regarded as statistically significant. More specifically, results of an error analysis of the 3udit
process indicated that for NO at 400 and 900 ppm, differences greater than 1.1% for both ranges may be
regarded as statistically significant; for S02 at 300 and 1500 ppm, differences greater than 13 and 2%,
respectively, may be considered statistically significant.
STABILITY EVALUATION
Rcsulls
The stability of the cylinder gas is defined as the percent difference between the concentrations
measured in 1991 and 1993. Figure 2 is a graphical presentation of these percent differences. The average
differences for S02 were -0.66 and +0.41% with associated standard deviations of the differences of 0.58 and
0.31% for the 300-ppm and 1500-ppm concentrations, respectively. The average differences for NO were
-0.92 and -1.16% with associated standards deviations of the differences of 0.55 and 0.37"?!: for the 400 ppm
and 900-ppm concentrations, respectively. In summary, 100% of the results fell within the ±2% range,
indicating that the concentrations did not change over the past two years.
The results were evaluated for differences between manufacturers for the different pollutants. This
was accomplished by determining an average difference and comparing the difference of each manufacturer to
this average, difference fur nitric oxide and sulfur dioxide. Figures 3 and 4 give a graphical presentation of
how each manufacturer's difference compared to the average difference for nitric oxide and sulfur dioxide.
Note that the confidence intervals all overlap zero percent difference, lite half-width of the intervals represent
the size of difference that would be required to be declared significant at the 5% level, Ihese results indicate
that no single manufacturer is different from the others.
One method used in the past to evaluate the stability of gases was to calculate the linear regression
coefficients of concentration onto the time between analyses and evaluate the. average slope calculated for each
concentration range. These results indicated that S02 changed -0.082 ppm per month and +0.250 ppm per
month with associated standard deviations of 0.072 and 0.186 for the 300-ppm and 1500-ppm concentrations,
respectively. The results also indicated that NO changed -0.152 ppm per month and -0.439 ppm per month
with associated standard deviations of 0.888 and 0.135 for the 400-ppm and 900-ppm concentrations,
respectively.
Despite the fact that the statistical analysis results indicate no change in cylinder gas concentrations,
the. graphical presentations seem to indicate a trend for specific cylinder gas groups. Two kinds of systematic
change can account for the apparent drift in cylinder gas concentrations: actual drift in the true cylinder gas
concentration and drift or systematic change in the measurement system. Conventional statistics do not
adequately differentiate, between systematic changes. Professional judgement is a powerful tool, but its
subjectivity does not necessarily fit with conventional statistics. Conventional least-squares regression analysis
was pci formed on the data in an attempt to lest whether the drifts of different manufacturers are different and
to te-st for change in the measurement system. These, tests were rather weak in that cylinder drifts would need
to differ by more than 4% to have a fair chance of detection. One significant finding of the analysis is that
the SO, measurement system behaved differently at the two levels tested (300 ppm and 1500 ppm). Aside
from that, the analysis provided no clue as to whether the apparent drifts were, caused by true drifts or
measurement system changes. It would seem unusual to have so many different cylinders drift in the same
manner.
Uncertainty Associated With Stability Evaluation
The same sources of error that existed during the accuracy assessment continue to exist during the
stability evaluation. Additional sources of error, however, mav include a shift in the NIST values, additional
calibration errors, or a random error that appears, by chance, to be systematic. A shift in NIST values is
minimized by conducting calibrations with multiple SRMs and defining linearity by using that portion of the
instrument's response that represents ±1% at the 95% confidence interval. SRMs that arc potentially different
from other SRMs would become visible in this type of system. The 95% confidence Interval for either the
1991 or 1993 analysis was ±2%. Combining these analysis errors yields a stability evaluation error of x3c/c at
the 95% confidence interval.
510
-------
CONCLUSIONS
The following conclusions were made from the stability evaluation:
• Cylinder gas concentrations appear to have changed as a group.
• No one manufacturer's cylinder was significantly different in terms of stability.
• Linear regression analysis could not conclude that the cylinder concentrations changed at all.
• The cylinder gas analysts was sufficiently sensitive to be able to detect instability of any single
manufacturer whose drift may have differed from the group by more than 3%,
DISCLAIMER
The information in this document has heen funded wholly or in part by (he United Stales
Environmental Protection Agency under Contract No. 68-D1-0009 lo Research Triangle Institute. It has been
subjected to Agency review and approval for publication. Mention of trade names or commercial products
does not constitute endorsement or recommendation for use.
REFERENCES
1. "Procedure I. Quality Assurance Requirements for Gas Continuous Emission Monitoring Systems
Used for Compliance Determination," U.S. Environmental Protection Agency, Code of Federal
Regulations. Title 40, Part 60, Appendix F, 1987.
2. 'Quality .Assurance Requirements for State and Local Air Monitoring Stations (SLAMS)," U.S.
Environmental Protection Agency, Code of Federal Regulations, Title 40, Part 58, Appendix A, 1987.
3. 'Quality Assurance Requirements for Prevention of Significant Deterioration (PSD) Air Monitoring,"
U.S. Environmental Protection Agency, Code of Federal Regulations, Title 40, Part 58. Appendix B,
1987.
4. "Procedure for NBS-Traceable Certification of Compressed Gas Working Standards Used for
Calibration and Audit of Continuous Source Emission Monitors (Revised Traceahi'ity Protocol No.
1)," June 1987 in Quality Assurance Handbook for Air Pollution Measurement Systems, Volume III,
Stationary Source Specific Methods, Section 3.0.4, U.S. Environmental Protection Agency, EPA-600/4-
77-027b."
5. "Procedures for NBS-Traceable Ccrtilication of Compressed Gas and Permeation Device Working
Standards Used for Calibration and Audit of Air Pollution Analyzers (Revised Traceability Protocol
No. 2)." May 1987 in Quality Assurance Handbook for Air Pollution Measurement Sy.le.ms, Volume.
II, Ambient Air Specific Methods, Section 2.0.7, U.S. Environmental Protection Agency. P.PA-600/4-
77-027a.
6. Coppedge, E.A.; Logan, T.J.; Midgett, M.R.; Shores, R.C; Messner, M.J.; Murdoch, R.W. "Accuracy
Assessment of EPA Protocol Gases Purchased in 1991," Journal of the Air and Waste Management
Association 1992 42:12, 1617-1619.
51 1
-------
5.00%
4.00%
Z o voo%
e o
OS ». 00%
»-»
5 T? o.u)%
<¦> 2'
u ^
£ *? •! .00%
<_
£ c
.2 « ?.00%
« S
5 ^ -J00%
K
-4.00% --
•5.00% ¦
Accuracy Assessment
1991
S»
S02
NO
:00 4U0 600 800 luo.1 IZUO
PPM, Analyzed by RTI
Figure 1. Protocol gas Accuracy assessment.
5.00% -
4.00t -
3.00% |
65 O !
£ r 2oo« j
5 | 'aw- t
5 S »oo% 4 -
«s
.Z. O -2.W%
-3.0095?
•4.00%
•5 00%
Stability Analysis
1991-1993
"» %
s.1
S02
NO
400 600 >oo iooc i mo
PPM, Analyzed by RTI
Figure 2. Protocol gas stability analysis.
5P
-------
S02 Audit Gas Stability
Manufacturer vs. Manufacturer
1.50%
^ w> i or* -
11
yZ o 0.50* -
£ ^ o.oo?,
fc 5
a. £ -o.5os>
4; O
~ rA i.ooa
JS cn
^ o
as C :.5IW.
5 6 7
Manufacturer
.- i gn re
3. S02 cylinder gas stability by manufacturer.
2.00*
©
T-
o
l.5C9fc
o
w
*
c
'oB
1.00%
w
>
i
«
o\
0.50*
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a*
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c
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u
cs
o*
-0S0*
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<
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«
a*
a
! -5C*
k~-*
•?oc-.
NO Audit Gas Stability
Manufacturer vs. Manufacturer
¦15 6
Manufacturer
Figure 4. NO cylinder gas stability.
512
-------
Intentionally Blank Page
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SESSION 11:
FT1R STUDIES
-------
Intentionally Blank Page
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Open Path FTIR Air Quality Measurements
at a Petrochemical Complex in Brazil
Robert H. Kagann*
AIL Systems Inc.
Commack Road
Deer Park, N. Y. 11729
Neuza Neves and Felipe Villas Boas
CETREL SA
Camafari, Baliia, Brazil
ABSTRACT
An open-palh FTIR sensor was used to determine the characteristic air pollutants at ten different
locations in a large petrochemical complex in Bahia, Brazil. These measurements were part of an initial
survey in preparation for a measurement program which will use both open path FTFR and GC / MS
analysis of collected air samples) to characterize the air quality within the complex and to obtain emission
rates of the individual sources In this initial survey, a total 17 different compounds were measured with
the FTIR sensor, including the polar species, ammonia and acrylonitrile.
INTRODUCTION
An Open-path FTIR (OP-FTIR) was used to determine the characteristic air pollutants at ten different
locations at the Camagari Petrochemical Complex (Polo) in Bahia, Brazil. These measurements, using
both OP-FTIR and GC / MS analysis of collected air samples, comprise the initial survey phase of a
CETREL program to characterize the air quality within the complex and to obtain and characterize
emission rates of the individual sources.
CETREL - Empresa de l'rotegao Ambiental S.A. is an environmental engineering company which is
working with the State of Bahia CRA (environmental agency) to develop a Source Pollution Control
Program (SPCP) to cover the entire Complex CETREL operates a centralized waste treatment plant,
treatment and disposal facilities and an incineration unit. In addition to their remediation services,
CETREL also provides soil, water and air quality monitoring services.
Over the last few years, the interest in applying OP-FTIR techniques, to air quality measurements in
the United States, has accelerated.1 These techniques have been investigated for different applications,
including Superfund remediation monitoring,^ emergency response,5 waste water treatment4 and sludge
treatment monitoring,3 fence'ine monitoring,6 production facility monitoring,7 measurements in DOE
treatment, storage and disposal facilities,8 and industrial hygiene9 and other indoor10 applications. In the
present study, OP-FTIR is used to survey fugitive chemicals in a large petrochemical complex in Brazil.
MEASUREMENTS
The OP-FTIR used in this study was used in a unistatic configuration with a single 12 inch Cassegrain
telescope A retroreflector array was used to return the beam. The resolution of the infrared spectra was
1 cm"1. Chemical concentrations were obtained from the spectral data with a multicomponent least-
squares (CLS) algorithm.
The measurements were made at ten different locations within the Complex in this initial phase of the
program, which took place in the period from August 28 to November 3, 1993. Figure 1 shows the
locations of the ten measurements on a map of the petrochemical complex. The locations of the
At the time of these measurements, author was with MDA Scientific, Inc.
517
-------
measurements are indicated by the labels PI to P10, where the P designates the program label, POLO.
Each location was chosen because it was downwind of a suspected emission source at the time of the
measurement A list of the chemicals detected with the OP-FTIR at the ten individual sites and the range
of the concentration measurements are given in Table 1
A 115 volt, 1 KW gasoline generator was used to provide power to the instrumentation at the ten
measurement sites. The resolution of the spectral measurements was 1 cm*1 and the signal-average times
ranged from 45 seconds to 10 minutes. The system was typically configured along the side of roadways
with the infrared beam at a height of ~ one meter. The one-way pathlengths, for the infrared beam, ranged
from 27 to 16S meters and were chosen to optimally encompass the plume (as identified by odors). Since
suspected emission sources were widely distributed around the complex, it was not feasible to measure
"upwind" background spectra. At each site at least one "zero-path" background was measured. During
these measurements, the retroreflector array was placed in front of the telescope tube at a distance of
several inches A disadvantage to using "zero-path" backgrounds is that they do not contribute to the
cancellation of the interfering water vapor lines, so that one must rely totally on the matchup of the water
vapor reference spectrum, used in the multicomponent CLS analysis, to the water vapor lines appearing in
the field sample spectra. In order to improve the analysis, a spectrum made of local "clean air" was
converted to a water vapor reference spectrum to be used in the analyses.
We further enhanced the data from the first site, (P0I.01), by using one of the field sample spectra as
the background. The preliminary analysis of the 23 field sample spectra, using a "zero-path" background,
indicated that the twenty sccondth single-beam file, labeled s3108v, did not have any measurable
absorption due to the three measured species (ethylene, cyclohexane, and n-hexane). This was probably
due to a momentary change in the wind direction. The use of s3108v as a background improved the
results considerably over the preliminary analysis. One must be careful in using this technique since any
absorption present in the spectrum used as a background will result in a negative bias However the
maximum magnitude of this bias should be less than the detection limits* of the species in question in the
initial analysis of the field absorbance spectrum using the "zero-path" background There have been
occasions when the this type of analysis (using a spectrum from the data set as the background) resulted in
detecting the presence of certain species which were not detected in the initial analysis An example of
this is in Run 1 at the fifth site (POLOS), were we detected benzene using this technique. The benzene
was not detected in the preliminary analysis Aside from POLOl and Benzene in P0L05, the
determinations reported in this paper were obtained using a "zero-path" background.
Figure 1 shows the locations of the ten measurements on a rough map of the Petrochemical Complex
The measurement locations PI to P10 correspond to the labels, POLOl to POLOIO (see Table 1 for the
summary of measurement results at these 10 sites)
Figure 2 shows a comparison of the field absorbance spectrum from POLOS, Run 3 to the reference
spectra of two of the species which have absorptions in this region of the field spectrum, methyl formate
and methanol The water vapor reference spectrum was subtracted from the field spectrum to better
display the underlying absorption bands. However this subtraction was not necessary for the
multicomponent CLS analysis, since the water vapor references was included in the analysis. The CLS
analysis was performed separately for these two species, since their absorptions do not overlap. The
results of the two separate analyses are 219 (19) ppb methyl formate and 691 (24) ppb methanol.
DISCUSSION
Table 1 shows a summary of the results obtained at the ten different sites at the Complex. Included ir
this table are the range of OP-FTIR. concentration measurements. The measured concentrations at two of
the sites, P0L05 and P0L08, are shown in Tables 2 and 3, respectively.
The detection limits are measured using the error residuals of the CLS analysis.
51X
-------
A total of fifteen species have been measured at Polo. Several of these (ammonia, acrylonitrile and
methanol) are polar molecules and are therefore difficult to measure using a sampling technique, due to
losses on the walls of the collection vessel and the walls of the plumbing used in the GC / MS equipment.
The OP-FTFR technique is being investigated because it offers the advantage of continuos monitoring over
an uninterrupted path and providing a real time response to any high level fugitive emission. The gas
sampling techniques are not amenable to this type of temporal and spatial coverage. The fact that the OP-
FJ'IR detection limits, for many species, are higher than they arc for the conventional air sampling
techniques is strongly mitigated by the ability to provide real-time feed-back on the chemical environment,
and to allow an emergency response to an accidental release of dangerous levels of chemicals.
Measurements made by other techniques indicate that benzene and other BTEX (Benzene, Toluene,
Ethylbenzene and Xylenes) compounds are present at the Complex. Because of the health hazards relating
to these compounds, it is important to include BTEX in the OP-FT1R measurements In the present set
of measurements, with the exception of one, the concentrations of these compounds were below the
detection limits. We measured the detection limits at some of the locations for benzene, toluene and m-
xylene, and obtained values which ranged from 11 to 240 ppb, 12 to 450 ppb, and 17 to 550 ppb,
respectively. These values varied because of changes in the path length, humidity levels, interfering
species other than water vapor, and signal to noise. However we did obtain one measurement of benzene
at P0I.05, in an optimized analysis where Run 2 (with little or no benzene) was used as the background
for Run 1. The results of the analysis of benzene for Runs 1, 3 and 4 are shown in Table 2. The results
degraded Runs 3 and 4 for two reasons. The pathlengths for these two runs was increased from 65 to 125
meters, one way, so the background from Run 2 does not optimize this two Runs because of imperfect
water vapor cancellation. The second reason may be even more important. Methanol has an interfering
absorption spectrum at 1031 cm-1 This band completely overlaps the benzene band at 1037. In Run 1,
methanol was below the detection limit of 18 ppb In Runs 3 and 4 methanol was present at the
concentrations 691 and 284, respectively The detection limits for benzene for these two runs (< 148 ppb
and < 68 ppb, respectively), seem to correlate with the methanol concentration. Because of the
importance of the BTEX compounds, we may initiate a program to investigate developing an analytical
algorithm to improve the detection limits on benzene by lowing the residuals due to the water and
methanol absorption.
This program was preliminary and was performed in order to acquire information on the chemical
environment at Polo to facilitate the future programs which include a complementary use of air sampling
and OP-FTIR. The main purpose of the present measurements was to perform a survey. At this stage,
validation of the data was not necessary, so no quality assurance procedures were used. Quality
Assurance procedures will be developed in the later stages of the program
CONCLUSION
This preliminary study lays the groundwork for establishing a continuos air quality monitoring
program which will use both the OP-FTIR sensor and air sampling - GC / MS techniques in a
complementary fashion and for intermeasurement quality checks. Quality assurance (QA) procedures for
the OP-FTIR will be developed in the next phase of the program.
REFERENCES
1 W. B. Grant, R. H. Kagann, W. A. McClenny, "Optical Remote Measurements of Toxic Gases," J.
Air & Waste Management Assoc. 42, 18-30 (1992).
2. T. H Pritchet,, D. M. Mickunas, T. R. Minnich and R. Kricks, "The U S. EPA Environmental
Response Team's Experience with OP-FTIR at Superftind Sites and the Lessons Learned," AVVMAI
SPIE international Conference on Optical Sensing for Environmental Monitoring, Atlanta, Georgia
(October 11 - 14, 1993)
519
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3. T. R Minnich and R L. Scotto, "The Role of Open-Path FTIR Spectroscopy in the Development of a
Successful Accidental Release Detection Program," AWMA / SPIE International Conference on
Optical Sensing for Environmental Monitoring, Atlanta, Georgia (October 11 - 14, 1993).
4. R. H. Kagann, W. A. Butler and J. R. Small, "FTIR Open Path Monitoring of Fugitive Emissions
From a Surface Impoundment During a Bioremediation Test Program," EPA / AWMA International
Symposium on Measurement of Toxic and Related Air Pollutants, Durham N C. (May 4- 8, 1992).
5. D. E. Pesscatore, R. J. Kricks and S. H. Perry, "Use of Open-Path FTIR Spectroscopy to Investigate
Unknown Airborne Contaminants at a Sludge Dewatering Facility," AWMA / SPIE International
Conference on Optical Sensing for Environmental Monitoring, Atlanta, Georgia (October 11-14,
1993).
6. D. M Hull, W. F. Herget and R. L. Spellicy, "A Demonstration of Continuous Operation FTIR Fence
Line Monitors in Petrochemical Environments," AWMA / SPIE International Conference on Optical
Sensing for Environmental Monitoring, Atlanta, Georgia (October 11 - 14, 1993).
7. N. Dando, L. Schneider, T. Montgomery and J Gibb, "Applications of Open-Path FTIR
Spectroscopy for Characterizing Fugitive Emissions at Metal Production / Fabrication Plants,"
AWMA / SPIE International Conference on Optical Sensing for Environmental Monitoring, Atlanta,
Georgia (October 11 - 14, 1993).
8. R H. Kagann, J. Jolley, Doug Shoop, Michael Ilankins, and James Jackson, "Open-Path FTIR
Measurements of Spatial Distributions of Chemical Emissions at Treatment Storage, Disposal
Facilities," Annual Meeting of the Air & Waste Management Association, Denver, Colorado (June 13
- 18, 1993).
9. Y Li-Shi and S. P. Levine, "Evaluation of the Applicability of Fourier Transform Infrared (FTIR)
Spectroscopy for Quantitation of the Components of Airborne Solvent Vapors in Air," Am. Ind. Hyg.
Assoc. J. 50, 360 - 365, (1989).
10. J. O Zwicker, W. M. Vaughan, R. U. Dunaway and R. H Kagann, "Open-Path FTIR measurements
of Carpet/Water Sealant Emissions to Determine Indoor Air Quality," AWMA / SPIE International
Conference on Optical Sensing for Environmental Monitoring, Atlanta, Georgia (October 11-14,
1993).
TABLES
Table 1. The range of concentrations measured with the QP-FTIR at the ten POLO sites.
Site
Date
1993
Methanol
(ppb)
Cyclo-
Hexane
(PPb)
Ammonia
(PPb)
Ethylene
(PPb)
Propylene
(PPb)
n-
Hexane
(PPb)
Methyl
Formate
(PPb)
PI
8/31
7-450
3- 180
P2
9/17
74-210
2-260
60 - 600
P3
9/24
74 - 170
60 - 270
P4
9/28
44 - 1770
85 - 150
P5
9/28
280 - 690
10-75
20-41
220
P6
9/28
18 - 27
7
21 - 240
1*7
9/28
34-68
11 -25
35 - 160
81
P8
10/29
33- 131
33-45
17 - 130
150 - 620
265
P9
11/02
48-69
42 - 581
P10
11/03
7-50
81 - 127
520
-------
(Table i continue
Site
Date
Methyl
Acetate
Acrylo-
Nitrile
Form-
aldehyde
Dimethyl
Ether
Iso-
butanol
CHC1F2
Propane
1993
(PPb)
(PPb)
(PPb)
(PPb)
(PPb)
(PPb)
(PPb)
PI
8/31
P2
9/17
P3
9/24
P4
9/28
110- 190
36 - 40
85 - 260
P5
9/28
P6
9/28
P7
9/28
| P8
10/29
| P9
11/02
15-18
150 - 220 |
| P10
11/03
64 - 101
8.4-19
Table 2. Table of OP-FTIR concentration determinations al P0L05. With the exception of
benzene, "zero-path" backgrounds were used. The benzene absorbance spectrum was
created using the single-beam spectrum from Run 2 (File A280902). The numbers in
File
POL05
Time
9/28/93
Path
Length
(m.)ow
Benzene
(PPb)
Ammonia
(PPb)
Methanol
(PPb)
Methyl
formate
(PPb)
Cyclo-
hexane
(PPb) !
A280901
7:48
65
6.0(1.9)
20.3 as
< 18
< 567
64.4(4.9) i
A280902
7:53
65
41.6 (1.6)
< 20
< 61
75.9(8.4) I
| A280903
8:05
125
< 148
37.J_£2_19)_|
i 691J24)
219(19)
18.8(4.6)
A280904
8:15
125
< 68
19.3 (2.9)
284 (13)
r < 57
9.9(1.9)|
Table 3. Table of OP-FTIR concentration determinations at P0L08. All results shown here are
from CLS analyses of absorbance spectra created using "zero-path" backgrounds. The
numbers in the parentheses are equal to three times the estimated standard deviation.
File
POLOS
Time
10/29
1993
Path
Length
(m) ow
Ethylene
(PPb)
Propylene
(PPb)
Methanol
(PPb)
Cyclo-
huxane
(PPb)
n-
hexane
(PPb)
A29A3001
11:39
140
78..3 (5.9)
297 (35)
107.6 (9.9)
< 30
32.9J7.2)_
< 12
482 (18)
A29A3002
11:44
140
81.2 (5.7)
616 (54)
59 (12)
A29A3003
11:50
140
56.8 (5.7)
356 (38)
72.0 (8.3)
< 13
177(13)
A29A3004
11:52
140
108.9 (8.0)
521 (57)
77(11)
< 12
200 (13)
A29A3005
11:55
140
48.8 (4.6)
153 (23)
104.6(9.1)
< 12
213 (12)
A29A3006
12:09
140
17.1 (5.6)
< 69
124.3(9.1)
< 13
193(10) !
A29A3007
12:10
140
108.0 (7.4)
181 (23)
115 (11)
44.7 (9.2)
581 (21) 1
A29A3008
12:11
140
128.8 (8.5)
456 (58)
76(11)
< 16
479 (17) 1
A29A3009
12:12
140
32.5 (4.1)
229 (23)
33.4 (8.3)
< 10
71 (10) 1
A29A3010
12:13
140
31.3 (4.8)
192 (23)
64.4 (9.1)
< 10
43(10) 1
A29A3011
12:15
140
81.3 (7.2)
279 (40)
131.1 (11)
< 12
160(12) 1
521
-------
FIGURES
Muat Ainjnla '
vW
1
<® S
P7
\
\
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i® psi
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'/
F 1
COFENE 1
i ->
CHMAP
3
CFC 1
4
COPENER 1
6
CEMAN
8
CJBA-GEIGY
10
CIQUINE
13
POLrTENO
14
POLIALDEN j
15
PRONOR
16
POUTROnLENO
17
ULTRAQUtMTCA
18
OXITENO
19
BASF •
22
CEI"RHL-Incinerator
25
SILINOR
28
ACRINOR
31
ANTARCTICA
1 32
UQUI1) CARHON1C
J 33
MKTANOR j
1 34
POUOI.EFINAS
35
SU1.FAB
38
NHROCARBONO |
1 42
NTTROFfiRTD. |
J 43
MKLANOR 1
Figure 1. A Map of the Petrochemical Complex showing (he Ten Measurement Locations (PI to P10), The individual
plants within the complex are designated with the encircled numbers. The names of the plants in the vicinity
of the measurements arc listed on the right. Table 1 gives the names of the gaseous chemicals detected with
the OP-ITIR at the ten locations and the range of concentrations measured
X
I
\ i
A
/ \
J
/Vo _
X~v - \JX\
X/v „ A.-_~ -
X
40\ |i
/ \j\
V ~ ' XJi/ \
\Vtveoi;Tyers (d — 1)
Figure 2 Comparison of the field absorbance spectnini from P0I05. Run 3 to two of the reference spectra used in
the CLS analyses. Top trace: field spectrum over 125 meter one-way path, middle trace: 533 ppm-mcter
methyl formate reference, bottom trace: 27 ppm-meter methanol reference. The water vapor reference
spectrum was subtracted from the field spectrum in order to better display the shape of the methyl formate
band The field spectrum was averaged for 5 minutes and a "zero-path" background was used to create
the absorbance spectrum The CLS analysis was performed separately for these two species, since the
absorptions do not overlap 'I"he results of the analyses on this portion of the field spectrum arc 219 (19)
ppb methyl formate and 691 (24) ppb methanol.
-------
Open-Path FTIR Absorption Measurements at Urban and Industrial Sites in Germany -
Two case studies
Torsten Lamp, Guntlier van Haren, Konrndin Weber and Johannes VVeidemann
Fachhochschule Diisseldorf
Faehbereich 04, Maschinenbau unci Verfahrensteclmik
Josef-Gockeln-StraBe 6
40474 Diisseldorf
BSTRAC.T
Open-path FTIR absorption measurements have been performed at urban and industrial sites in Germany,
ic first direct intereomparison in Germany between open-path FTIR measurements and the official
Msurement network of the environmental state agency will be presented. Moreover the results of ammonia
;asurements in the complex atmosphere of a refinery plant will be addressed.
TRODUCTION
The FTIR open-path measurement technique has already found various applications in the USA. In
:rniany interest in this method is steadily growing. In the Fachhochschule Diisseldorf the method is being
oloited for various applications at industrial uiban and rural sites in order to make it usable not only for
earch, but even for official tasks in the air pollution surveillance. Our experience will be brought into the
ndardization of this method in a German and maybe a European standard.
We used a commercial system with one wave number resolution for our measurements The measurement
up was monostatic in every case. Monostatic means. The infrared light was sent out by a transmitter/receiver
:scope towards a retroreflector, typically separated by an absorption path of several hundred meter. The
ected light was recollected again by the telescope and analyzed in the FTIR spectrometer, thus giving the
h-averaged concentration of the air pollutants of interest. The method is described in more detail e g in [1,2]
ercomparison Measurements at an Urban Site
The urban measurement site was situated at the outskirts of the German city of Cologne. This
isurement site was chosen because it was known that sometimes very high methane concentrations could be
nd there and, additionally, photo-chemical smog situations in summer were noticed. Several potential sources
,ir pollution could be found in this region, for instance industrial plants, traffic, waste sites and waste-water
tment basins.
An official station of the Environmental State Agency of North Rhine-Westphalia, equipped with
dard monitoring systems, was placed at this site as part of the air pollution measurement network for
:inous measurements of the state, so that we were able to intercompare our results with the data of the
rial network of the state.
The first aim of our measurements was to find out how well our results matched the official
surements of the state agency.The second aim was to find out what the most important source of the high
lane concentration was
We made the measurements on two different days at that site with a temporal delay of about two weeks
ihance representativeness. For these measurements the spectrometer was placed near the station of the
ronmenta! State Agency so that direct intereomparison of the two systems was possible Down in a street
etroreflcctor was installed about two hundred meters away from the spectrometer down in a street In the
;t, where we made our measurements, there was only little traffic. Flowever. a main street with heavier traffic
situated nearby.
The measurements between both systems intercompared very well although the weather conditions
gcd from snowfall to rain and sunshine. The atmospheric temperature changed between -2 °C and +6 °C.
he first day (Fig. 1,3) the mean difference between both measurements was less than the difference of both
urements during the second day (Fig. 2,4). This can easily be explained by the fact that for the evaluation
3 data of the second day the same synthetic background had been used, which was derived from the spectra
523
-------
of the data of the first day. tor this reason the shift of the baseline caused by the strong absorption of CO? an;
water vapor in the seeond measurement was not compensated as well as in the first measurement. Another
reason is the continously changing winddircction during the second day. This stresses the differences between
point-sensor and a path-integrating system.
The measurement of methane showed a better agreement than the measurement of CO.
The very strong increase in the CO emissions, caused by a larger numbei of cars in the maiiistreet in tl
afternoon hours, can clearly be seen (Fig. 1).
Figure 2 demonstrates the CO measurements of the second day. Again you can see a good agreement
between botli measurement systems. The overall trend of the concentrations increased in parallel.
In the measurement of the second day, slightly higher concentrations at about noon and in the late
afternoon can be seen The first concentration maximum could be correlated to an enhancement of traffic in t
small street, where the measurements had been performed The. second maximum was due to the increased al
work traffic on the main street nearby.
Again it should be stressed at this point that the agreement between the FTIR open-path measureme-
and the measurements of the oiYicial measurement station were very satisfactory. So it could be clearly
demonstrated that the FTIR-method can produce reliable results. Moreover, it was possible to make
measurements even during heavy snow fall needing only about half an hour from arriving at the measurement
to the beginning of the measurements.
In addition to the CO measurements we evaluated the spectra for the measurement of methane, whic
was the compound the people in that area were mostly interested in. Fig. 3 demonstrates the measurements •
methane of the point monitor of the official network in comparison to our measurement. Again a very good
agreement of the two measurement systems within a few percent could be registered. By the way, the dip in
black line is caused by a big garbage truck.
The methane concentration at that day remained fairly constant just above the normal atmospheric v,
so no alarming feature could be found in the measurements during that day.
During the second measurement day the methane concentrations showed a very dramatic increase di
a certain period. For the time of one hour, between 2:30 pm and 3:30 pm, both measurement systems show'
significant increase. In order to find out the reason for this feature we correlated the measured concentratio
with the wind data. The direction of the wind is plotted in Fig. 4 as well. So by corrcllating the wind data w
the concentration data a waste water treatment basin, about two miles from the measurement site, could cle
be identified as the source of the high methane concentrations in that day, whereas the waste site as well as
industrial areas could be excluded as the methane source
This measurement shows that the general trend of changing concentrations is still visible even when
background is not exactly matched to the measurement situation. This is important for continuous automat';
monitoring over several days where the trend of the emissions is often more important than the exact value
We will perform additional measurements at this urban site during this summer, in order to get dat.'
situation of photo-chemical smog
In conclusion, we could prove at this urban site that the open-path absorption system can deliver re
results for methane and CO in an on-line mode even under adverse weather conditions. As all wc know, th
the first direct intercomparison between an open-path FTIR system and official measurement systems in
Germany. Therefore it was of high importance that there was a very good agreement between our data ant
data of the official measurement network. This will surely increase the confidence in these innovative meth
Measurement at an Industrial Site in Germany
We performed different measurements at industrial sites in Germany. In this paper we want to
demonstrate a measurement which had been taken at an ammonia tanking facility within the area of a refin
We chose this industrial site to demonstrate that with this method it is possible, to get results even in a ditl
industrial atmosphere with many interfering compounds.
At that site, ammonia storage tanks were refilled from railway tank waggons. We had positioned o
spectrometer on a little hill, about 380 m away from the tanking facility. The retroreflector was sited in su
position that the measurement path was downwind of the potential emission source of the tanking facilitv.
At the beginning of the measurement you can see nearly a constant level of ammonia concentratioi
(Fig 5). The measured concentration of about 7.5 ppb (5.7 pg/nv') was just above the normal atmospheric
-------
ncentration, which usually is given as 5 pph (3.8 ng/rrT). The black line represents the concentrations, which
:re evaluated using the Hanst library for the reference spectra. We got the dotted line by using the. MDA
rary, in which all reference spectra were measured in the laboratory with an spectrometer identical to ours.
However, for a very short time interval of about one minute we could detect a very sudden and drastic
¦rease. We were able to monitor this increase on-line at the site. As we heard later on, this ammonia emission
is caused by the fact that just at that time the tanking hose was removed from the waggon so that a part of the
nains of the ammonia in the hose could be released. If you refer the measured signal to the approximate
nension of the tanking facility of about 50 m, you get a peak concentration of the release of about 600 ppb
>5 ng/m'). It is remarkable, that this short emission could be detected by us on-line even at a distance of
D m outside the plant.
With this measurement we successfully demonstrated the potential of the method to monitor one
r.pound in an industrial environment
INCLUSION
The first direct intercomparison in Germany of FTIR open-path measurements with official measurements
carbon monoxide and methane is very satisfactory. We planned additional measurement campaigns together
li the environmental slate agency to extend the evaluation of the FTIR open-path system also for other
npounds like e.g. ozone in an urban area.
At the industrial site we successfully demonstrated the benefit of the FTIR open-path absorption method
on-line and remote monitoring even of sudden emissions.
Moreover, it could be shown that this measurement method can have advantages over point monitors for
tsuring fugitive emissions in a complex industrial situation. The measurements at the industrial site will be
tinued.
TERENCES
jriffiths, PR... de Ilaseth, J. A.; Chemical Analysis, Vol. X3 - i'ouricr Transform Infrared Spectrometry,
'.J. Elving, J.D. Winefordner, Eds.; John Wiley and Sons: New York 1986
Vebei. K., „Optical Remote Sensing of Air Pollution in the Troposphere, Techniques and Capabilities." in
Proceedings 1st IUAPPA Regional Conference on Air Pollution: Towards the 21st Century, Implications,
Challenges, Options and Solutions, 24-26 October 1990: Pretoria 1990; pp. 16/1-16/23
-------
sliding half-hourc-mcan-values
3.5 . ' 70
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3 : - - - T- - UJAt 60
2,5 1 .. .' . ... . . . J.. . / . ! 50
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i A ' • ' de\iation
o J_ ^... : o
11:00 1200 1300 1400 1500 1600 1700 1800
time/hhmm
Figure 1. Carbnnmonoxide measurement at urban site, first day.
sliding half1 hour-mean-values
1,5 ........... 90
li. . . : . . op-fur ' • : ¦ r 75
deviation
i lOO 12:00 13OO 1400 1500 16.00 17.00 18.00
time /hhanm
Figure 2. Carbonmonoxide measurement at urban site, second day.
-------
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igurc 3. Methan measurement at urban site, first day
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?ure 4. Methan measurement at urban site, second day
-------
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Figure 5. Ammonia measurement at tanking facility, 380 m
-------
Development of Quality Assurance Procedures in Open-Path FT-IR Monitoring
Edgar L. Thompson, Jr., Jeffrey YV. Childers, and George M. Russwiirm
ManTech (Environmental Technology, Inc.
P.O. Box 12313
Research Triangle Park, NC 27709
ABSTRACT
Data were collected over a period of two and one-half months as part of an ongoing program
to develop quality assurance (QA) procedures in open path Fourier transform infrared (FT-IR)
monitoring. A semi-permanent monitoring site with an FF 1R system in the monostatic
configuration was established over a grassy field with a total path length of 414 m. Spectral
measurements were made by acquiring 5-min co-averaged spectra at 15-min intervals over 7 to 8 h
starting in the morning and continuing through the afternoon. Measurements were also taken
continuously over a 36 h period. A daily protocol that included measuring the instrumental
electronic noise, the magnitude of the single-beam return signal, the baseline noise, and the
repeatability of the position and full width at half height of selected water vapor absorption bands
was followed. Ancillary measurements, including relative humidity, ambient temperature, and wind
direction, were also made. The ambient concentrations of carbon monoxide, methane, and nitrous
oxide were measured to assess the stability of the instrument and to investigate the feasibility of
.ising ambient gas concentrations for QA purposes.
INTRODUCTION
For open-path Fourier transform infrared (FT-IR) spectrometry to become an accepted
method for environmental monitoring, proper quality assurance (QA) procedures must be
sstablished. Kricks et al.: have discussed QA issues concerning the operation of open-path FT-IR
ipectrometers during field applications and identified several potential sources of error in the
neasurements. Russwurm'-1 developed a synthetic data set to illustrate the effects of spectral shifts
:nd interfering species on errors in least-squares-fitting (LSF) analyses and has examined the effects
if water vapor on the measurement of toluene. Weber et al.4 have addressed the need to develop
:xperitnental performance characteristics in optical remote sensing. Despite the attention that this
opic has generated, however, there is currently no consensus regarding the proper QA procedures
equired to validate open-path FT-IR data.
One of our primary goals is to develop procedures to determine rhe quality of data taken with
•T IR monitors. The study described here was designed to evaluate the stability of the instrument
nd the precision and accuracy of concentration measurements. The following criteria were used to
ssess the stability of the instrument: electronic noise, the magnitude of the return signal, rhe root-
lean square (rms) baseline noise, and the repeatability of the position and full width at half height
-WHH) of selected absorption bands. Ambient concentrations of methane (CH4), nitrous oxide
^,0), and carbon monoxide (CO) were measured to test the use of these data for determining the
recision and accuracy of the FT-IR open-path monitor. Measurements were made daily over two
id one-half months, from November 1993 to mid-January 1994.
XPERIMEXTAL METHODS
Spectral data were acquired by using an MDA (Norcross, GA) monostatic FT IR monitor
juipped with LabCalc software (Galactic Industries Corporation, Salem, Nil)- Each spectrum
insisted of 64 co-averaged scans recorded at a nominal 1-crn 1 resolution. Triangular apodization
as used. The collection of each spectrum required approximately 5 minutes. A spectrum was
ken every 15 minutes.
529
-------
Single-beam spectra were typically acquired over a 7- to S-h time period. Absorbance files
were created by ratioing the single-beam spectra to a synthetic background spectrum generated from
a 2048-scan single-beam spectrum recorded over the 414-m path. This background spectrum was
recorded at the beginning of the experiment and was used throughout the study. The data were
analyzed by using the MDA LSF package and reference spectra from a commercial library (Infrared
Analysis, Inc., Anaheim, CA).
The site, is located near 1-40, one of the main traffic arteries for the Research Triangle Park,
NC, area. The instrument was kept in a climate-controlled shed, which is heated during the winter
months and cooled during the summer months. The total path length was 414 m, and it extended
over an open, grassy field and a small parking area with very limited traffic. The beam path rose
from about 6 ft to 42 ft above the ground as it was directed from the FT-IR instrument to the
retroreflector, which was mounted on a tower.
RESULTS AND DISCUSSION
The instrumental electronic noise was measured each morning before the detector was cooled
with liquid nitrogen. This signal typically ranged between 600 and 620 counts. Shortly after the
detector was cooled, the instrument was aligned and the maximum return signal was recorded. The
return signal was recorded again (without realignment) around noon to check the stability of the
signal. On clear days the return signal ranged from 10,500 to 13,500 counts. (Sec Figure I.)
Certain atmospheric conditions caused the renirn signal to vary from day to day. 1-or example, the
return signal dropped by 20-30% during fog. On some mornings, when humidity was close to or
below die dew point, condensation or ice formed on the retroreflector, resulting in a lower return
signal in the early morning measurement. As the condensation evaporated, an increase in return
signal counts was measured. To remedy the problem of condensation, a heat lamp was mounted on
the tower and directed at the retroreflector. After the heat lamp was installed on December 10, the
noon and early morning return signals were nearly the same. Also, use of the heat lamp did no-
cause an increase in noise or detected IR signal.
The rms baseline noise measured over 26 days is illustrated in Figure 2. The baseline noise
was determined by collecting two back-to-back, 64-scan. co-added spectra. One spectrum was
ratioed against the other to obtain an absorbance file. The rms noise (in absorbance units) was
calculated over three spectral regions: 980-1020, 2480-2520, and 4380-4420 cm'1. During
operations when condensation did not form on the retroreflector, the baseline noise was on average
approximately 2 x 10"1 for the 980-1020-cm'1 region, 2.5 x 10'' for the 2480-2520 cm ' region, and
9 x lO'1 for the 4380-4420-em'1 region. During measurement periods when condensation formed on
the retroreflector, the baseline noise tor these regions increased to 9.7 x I0"4, 5.5 x HP, and
2.9 x 10% respectively.
The wavenumber stability of the instrument was determined by monitoring the peak position
and the FWHH of the water vapor singlet at 1014.2 cm"1. Band positions typical of data collected a
the beginning, in the middle, and near the end of the study are depicted in Figure 3. No shift in the
frequency was observed during this time period. Also, no shifts were observed in the 1-cm"1 spectr;
collected under a variety of weather conditions, including rain, freezing rain, sleet, snow, and low
(single-digit) temperatures. To determine if the water vapor singlet at 1014.2 cm 1 broadered, a
spectrum collected at the beginning of the experiment was subtracted from a spectrum in the middle
and end of the experiment. No broadening was evident during the middle of the experiment;
however, a slight broadening for some of the spectra at the end of the experiment was observed.
The HWHII of the water vapor singlet in spectra taken during different atmospheric conditions was
also examined. When a clear day spectrum was subtracted from any of these spectra, no broadenm
was evident.
The feasibility of using ambient gases for QA purposes was investigated. Ambient
concentrations of N20. CH.„ and CO were measured on a daily basis. Each morning between 0715
and 0930 the concentrations of these gases increased, then steadily decreased during the remainder
530
-------
of the day. However, concentrations of N,0 and CH4 remained within their expected ambient
levels, 250 ppb and 1.7 ppm, respectively. To determine whether the increases in concentration
during the first 3 h of operation were due to an instrument effect or to (Jie proximity of the site near
a major highway, data were collected continuously for 36 h.
Data were collected from November 17 at 0730 until 1730 on November 18. The CH.,
concentration data exhibited scatter during an early morning fog episode and decreased steadily
during the day. (See Figure 4A.) A step in the CH, concentration measurement was observed when
the liquid nitrogen in the detector was depleted at approximately 2345 on November 17. The CI1.,
concentration value was 1.70 ppm just before the liquid nitrogen was depleted, increased to 1.9 ppm
after liquid nitrogen was refurbished, and remained 10% higher compared to the previous levels.
The concentration data for CO showed a similar, stepped increase.
The CI14 concentration data exhibited irregular behavior during a 6 h period shortly after the
detector Dewar was refilled with liquid nitrogen. To determine if the instrument was operating
properly during this time period, the single-beam intensity at 987 cm'1 was measured from archived
spectra. The single-beam spectra had a lower intensity during the fog episode, then leveled off until
the detector ran out of coolant. (See Figure 4B.) After this sudden drop, the single beam intensity-
returned to its original reading and remained relatively constant throughout the remainder of the
experiment. This indicates that the instrument was working properly during the episode of high
measured CII. levels.
One other observation during this time period was that on November 17 a cold front moved
through the area in die late evening and the water vapor pressure dropped rapidly. Because the
water vapor spectrum is used as an interfering species in the LSF concentration analysis for CH„
the sudden change in water vapor pressure could have had an effect on the CH„ concentration
measurements. The relative concentration of water vapor along the path was determined by
measuring the peak area of the absorption band at 1014.2 cm Likewise, the relative concentration
of CH, was determined by measuring the peak area of the absorption band at 2998.8 cm'1. This
peak was chosen because the water vapor bands do not interfere with it. As shown in Figure 5, the
"dative water vapor concentration decreased rapidly when the front moved through the area. The
relative CH, concentration increased during this period. Similar trends were observed between plots
3f the CH,, peak area and CH,, concentrations determined by the LSF concentration analysis. This
ndicates that the change in water vapor concentration did not greatly affect the LSF analysis for
l'H4, and the fluctuations in the CR, concentrations were real.
:oxclusions
The data collected in this study indicate that for this particular FT-IR monitor the return
ignal and baseline noise are repeatable and are instrumentally stable over extended periods, but are
ubject to variations due to weather conditions. The peak positions and the FWIIHs of the water
apor singlet at 1014.2 cm ' were repeatable from day to day and were not affected by rain, freezing
ain, snow, or single-digit temperatures. The variability in die concentrations of ambient gases
mits their use in instrument stability studies and for QA purposes. A step in the concentration
leasurements associated with the depletion and refurbishment of detector coolant is not yet
nderstood. Future experiments using a QA cell with surrogate standards are planned to further
lvestigate this effect.
.CKNOWLEDCMENT
Although the research described in this paper was funded wholly or in part by the United
sates Lnvironmental Protection Agency through Contract 68-D0-Q106 to ManTcch hnvironmcntal,
e paper has not been subjected to Agency review and therefore does not necessarily reflect the
ews of the Agency, and no official endorsement should be inferred.
531
-------
REFERENCES
1. Kricks, R.J., Scotto, R.L., Pritchett, T.H., Russwurm, G.M., Kagann, R.H., and Mickunas,
D.B., "Quality assurance issues concerning the operation of open-path FTIR spectrometers,"
in Proceedings of Optical Remote Sensing. Applications to Environmental and Industrial
Safety Problems, SP-81, Air & Waste Management Association: Pittsburgh. 1992; pp 224-
231."
2. Russwurm. G.M., "Quality assurance, water vapor, and the analysis of FTIR Data," in
Proceedings of the 85th Annual Meeting and Exhibition of the Air & Waste Management
Association, Air & Waste Management Association: Pittsburgh, 1992; p 92-73.03.
3. Russwurm, G.M.. "Quality assurance and the effects of spectral shifts and interfering species
in FT-IR analysis," in Proceedings of Optical Remote Sensing. Applications to
Environmental and Industrial Safety Problems, SP-81, Air & Waste Management
Association: Pittsburgh, 1992; pp 105-111.
4. Weber, K., van de Wiel, H.J., Junker, A.C.F. and de LaRiva, C., "Definition and
determination of performance characteristics of air quality measuring methods as given by
the International Organization for Standardization (ISO) - applicability to optica! remote
sensing," in Proceedings of Optical Remote Sensing. Applications to Environmental and
Industrial Safety Problems, SP-81, Air & Waste Management Association: Pittsburgh, 1992;
pp 30-42.
16,000
14,000 -
c
12,000 -
3
¦
o
o
10,000 -
"5
c
8,000 -
a>
in
c
6,000 -
3
•
%
4,000 -
2,000 -
cc
,cp .ll* Cp' Qp1 <
P *o4 0®° O* Q* O* ^ ^
Date of Measurement
Figure 1. Return signal magnitude of the FT-IR monitor measured daily at 0700 (*) and
1200 (¦).
532
-------
0.005
0.004
W 0.003
0.002
0.001
¦M
+<$> ^ ^ _oN .cP _V» ,a° .-jS- cP> ,cf>
^ ^ ^ ^ ^eP Qfp 0C° Qa° ^e6 0eO ^ ^
Date of Measurement
"igure 2. The rms baseline noise measured between 980 and 1020 cm"1 (¦), 2480 at;d 2520 cm"
(•), and 4380 and 4420 cm': (*).
Q>
O
C
CI
XI
l_
o
«
a
<
1010
1020
1015
Wavenumbers (cm "1)
;ure 3. Repeatability of the position of the water vapor singlet at i014.2 em"1 measured on
(A) November 10, 1993, (R) December 22, 1993, and (C) January 4, 1994.
-------
4.0
£ 2.0
1.0
0.0
07:12
12:12
17:15
03:30
08:30
13:30
18:30
09:42 14:40 19:45 01:00 06:00 11:00 16:00
Time
Figure 4. Measurement of (A) ambient methane concentration and (B) single beam intensity at
987 cm'1 on November 17 and 18. 1993.
0.16
0.14 -
Si 0.12 -
< 0.10 -
< 0.08 -
0.06 -
0.04
07:12
12:12
17:15
22:15
03:30
08:30
13:30
18:30
09:42 14:40 19:45 01:00 06:00 11:00 16:00
Time
Figure 5. Measurement of the peak area of the 2998.8-cm'1 absorption band of methane (A) ?.
the 1014.2-cm4 absorption band of water vapor (B) on November 17 and 18, 1993.
534
-------
Adaptation of a Military FTS to Civilian
Air Toxics Measurements
James R. En gel and Rick K. Dorval
OPPIIA, Inc.
461 Boston Street
Topsfield, MA 01983
Phone: (508) 887-6600
Fax: (508) 887-0022
Abstract:
In many ways, the military problem of chemical agent detection is similar to the
ivilian problem of toxic and related air pollutants detection. A recent program to design a
text generation Fourier transform spectrometer (FTS) based chemical agent detection
ystem has been funded by the U.S. Army. This program has resulted in an FTS system
hat has a number of characteristics that make it suitable for applications to the civilian
leasurement problem. Low power, low weight, and small size lead to low installation,
perating and maintenance costs. Innovative use of diode lasers in place of HeNe
jfercnce sources leads to long lifetimes and high reliability. Absolute scan position servos
How for highly efficient offset scanning. This paper will relate the performance of this
astern to present air monitoring requirements.
^traduction:
The US Army has been developing field-rated spectroscopic sensors for chemical
jent detection for nearly 25 years. One of the first systems to be developed was LOPAIR
jong Path InfraRed). This system was a low resolution system using circular variable
Iter technology. A small number of these systems were built and used in coruunction
ith fairly basic spectral pattern recognition algorithms based on the Simplex technique,
good deal of confidence was developed in the application of these techniques to this
issive detection field problem. Limited resolution and sensitivity of the LOPAIR systems
ompted the examination of FTS systems, the first of which was called COLS* (Correlation
terferometer). This was a single system built to address the practicality of FTS for field
e as well as to provide a platform for the early study of extracting the detection
formation directly from the interferogram without, going through the transform process.
)th the LOPAIR and COIN systems were built by Block Engineering. Showing promise
a next generation technology for the Army's detection problem, an advanced FTS
stem was developed at Honeywell Electro-Optics Center. It consisted of a series of quasi-
eadboard instruments, the BMS (Background Measurement System) designed to collect
s necessary field data for the development, of algorithms; and the XM-21 system, a fully
Id rated FTS. Both of these systems were designed to operate in spectrum space. In
ne, the XM-21 went into production as the M-21 chemical agent detector. Brunswick
rporation purchased the Honeywell operation producing the M-21 and now
inufactures these systems for the Army and other Department of Defense components,
.e latest in this series of FTS instruments is the I,-SCADS (Lightweight-Standoff
emical Agent Detection System). This is an interferometer system initially designed for
> on an un-manned aerial vehicle and is intended to provide a standoff detection
lability for battlefield commanders. An essentially identical version of the L-SCADS
;tem is also being built as part of the Army's Armored Systems Modernization Program.
SCADS was jointly developed by OPTRA and IMO/Baird. As with many of the military
igrams today, contractors are encouraged to develop dual-uses for the technology
-------
embodied therein. The application of this sensor to monitoring and control problems in
the civilian sector is a natural response to these urgings.
The instrument developed under this program is described in detail elsewhere. (See
reference 1.) L-SCADS is a moderate resolution spectrometer using the classical Michelson
configuration of two flat mirrors and a compensator/beamsplitter pair in a 45/45 degree
configuration. Table 1 is a list of performance specifications. The spectrometer is designed
for use from 700 to 1400 wavenumbers, the fingerprint region of the infrared spectrum. It
is provided with variable resolutions from a high of 2 wavenumbers to a low of 16
wavenumbers. It operates in a continuous scan mode at a constant velocity for all
resolutions providing a range of scan rates (interferograms/second). The interferometer
has an aperture of 0.5 inch diameter and a field of view of 3 x 3 degrees. A 2X afocal
telescope transforms this into an aperture and field of view of 1 inch diameter and 1.5 x
1.5 degrees respectively. The system is quite small (6 x 7 x 10 inches); it weighs less than
13 pounds; and draws less than 24 watts at 28 volts DC input power. The output of the
system is an analog interferogram. Digitization, processing and data storage are all done
by other units.
Signal to Noise Ratio:
One objective of dual-use programs is to consider the application of the military
systems in a manner that minimizes additional engineering. Hence, an unmodified L-
SCADS sensor is used as the basis for the following performance analysis. A bistatic
system as shown in Figure 1 will be analyzed. The system consists of an unmodified L-
SCADS interferometer spectrometer observing a continuum source which is collimated and
projected by a 30 cm diameter (12 inch) optical system located 200 meters from the
spectrometer. Furthermore, in an attempt to relate this analysis to a real problem, the
analysis of the system performance will be done for the spectral interval of 780 cm1 to 90(
cm1, which is the spectral region often used for detection of phosgene, a pollutant of some
interest. (See reference 2).
In such a closed system the performance figure of merit is the radiometric signal to
noise. When that number is known the minimum detectable concentration path length of
different materials can be determined. The system signal to noise ratio can be expressed
as
N (i:
SNR = NESR
where SNR = the signal to noise (unitless),
Nc = the source radiance (w/cm2-ster-cm''), and
NESR = the system noise equivalent spectral radiance
defined at the source (w/cm2-ster-cm" ).
NESR = 'El (2
D* • n ¦ 0 • Av • \[Kt
area of the detector (cm2),
detector detectivity (cm-Hz'^/watt),
sy3tem efficiency (unitless),
system etendue (cm2-ster),
spectral resolution (cm1), and
integration time (see).
Aj
= the
D'
= the
n
= the
e
= the
Av
= the
At
= the
-------
Combining equations (1) and (2) yields
SNR - N. • P" • n • 6 • Av • (3)
A"
Since this analysis anticipates the use of an L-SCADS instrument, certain terms in
equation (3) are fixed and others are variable. Each term is discussed below.
N- Source Radiance: Without being specific, the source chosen for this analysis will
operate at 1000 K. Spectral radiance values for this temperature source over the 780 to
880 cm"1 spectral range are on the order of 3 x 10"4 watts/cm^ster-cm1, slightly less than
this amount at 780 cm"1 and slightly more at 880 cm1.
D*. Detector Detectivity: A peak D* (at 12 |im or 833 cm1) of 4 x 1010 cm-Hz,a/watt is
assumed even though the L-SCADS MCT detectors are somewhat better than this. Shorter
and longer wavelength values follow the usual D* curve.
n. System Efficiency: Over the spectral interval under consideration the system efficiency
of the L-SCADS interferometer is approximately 0.2.
8. System Etendue: The etendue (or area - solid angle product) of a system numerically
describes the geometric light gathering capability of the system. The etendue of the
system under discussion will be determined by the interferometer entrance aperture and
the projector aperture and their respective separation by the relation
where
Since
A, = 5.07cm2
A^ - 7.07 x 102 cm2,
R = 200 m = 2 x 104cm, then
0 = 8.96 x 10 scm2-ster.
0 = the etendue for the system (cm2-ster),
Aj = the interferometer collector area (cm2),
Ap = the source projector area (cm2), and
R = the source-interferometer separation (cm).
ftv. Spectral Resolution: For the analysis, the highest resolution of the L-SCADS (2 cm-1)
vill be used.1
1 From modulation cffiraency considerations, the maximum allowed obliquity angle within the interferometer
is given a»
Av
where u = the obliquity haif angle (radians),
Av = the spectral resolution (cm-1), and
v = the highest optical frequency (cm-1).
537
-------
At. Integration Time: Assuming ail observation efficiency of 0,8 and an observation time of
10 seconds, the integration time for this analysis is 8 seconds.
A.i. Detector Area: L-SCADS has a square detector of linear dimension 5 x 10 2 cm.
Using the values from above, equation (4) can be used to generate the SNR curve
shown as Figure 2.
Minimum Detectable Concentration
The absorbance at specific wavelengths is related to the concentration path length
as
A - M • c • d (6)
where A = the absorbance (unitlcss),
M = the absorptivity (ppm-meter)l,
c = the concentration (ppm), and
d = the path length (meter).
From measured spectra the absorbance is quantified as
A - -log.
(7)
where I = the spectrum obtained in the presence of an
absorber, and
I0 = the "clean air" spectrum taken under the same
conditions as I.
Since the noise in each spectrum is a constant, I and I„ are related to their respective
SNR's by the same factor equation (7) can be rewritten as
-log.
SNR't
mwj; (8)
By defining the minimum detectable absorbance as that which reduces the transmission by
3 times the noise level, from equation (8)
Together with the interferometer mirror area this definee the maximum allowed ayetem etendue
- A* * * ¦ u2
where Am = the interferometer mirror area (cm2).
For L-SCADS the interferometer mirror radius is 0 635 cm giving
' (0 63ft;2 • n
m . _ . f 2 cm-
[780
cm
- 1.02 x 1CH cms-3ter
Since equation (4) yields a system throughput of 6 96 x 10"* enr-ater this condition is clearly met.
-------
-log.
SNR - 3
"SNTT
(9)
Using the SNR's from Figure 2, a plot of Arai. is presented as Figure 3. Across the band,
is approximately 10-1.
From the earlier discussion regarding etendue it is noted that the system
throughput could be increased by slightly more than 103 times leading to an improvement
in of the same magnitude. The right hand axis of Figure 3 represents Aml, for a
system which would include a modest 25cm (10 inch) diameter collector on the
interferometer.
Conclusions:
The Ij-SCADS sensor has the potential for operating as a transmissometer system
element. The minimum detectable absorbance projected for this system compares very
favorably with systems that are substantially larger and heavier and less suitable for field
use.
References:
1 Engel, James R., Dorval, Rick, and Carlson, David L, "Field Portable Fourier
Transform Infrared Spectrometer System", Second lnt'1 Conf. Montgomery, TX, Jan, 1994.
2. Hanst, Philip L and Hanst, Steven T., Gas Measurement in the Fundamental
Infrared Region, Volume 1, p.12.
Table I
Performance Specifications
Spectral Range: 700 - 1400 cm-1
Resolution: 2, 4, 8, 16 cm-1
Scan Rate: 5, 10, 20, 40
scans/3econd
Field of View: 3x3 degrees
Spectrometer Aperture: 0.5 in diameter
Operating Mode: Passive (Emission)
Figure 1
Transmissometer System
Spectrometer
2.5 cm Aperture
200
meters
Source Projector
30 cm Aperture
539
-------
Figure 2
Signal to Noise Ratio
(2 cm-1, 10 sec Observation, 200 m)
1E+04
o
1E+03.
to
c
O)
C/>
1E+02-
780 790 800 810 820 830 840 850 860 870 830
Frequency (cm-1)
Figure 3
Minimum Detectable Absorbance
(2 cm-1, 10 sec Observation, 200 m)
1E-02- -
_ —c1E-04
1E-03
1E-04
1E-05 a
t—i—-1E-06
780 790 800 810 820 830 840 850 860 870 880
Frequency (cm-1)
540
-------
Joint Observations of the ICTL Ozone Lidar and V1PS System
during the lx>s Angeles Free-Radical Study
Yanzeng Zhao", R. Michael Hardest}*, Daniel Wolfe", and John Gaynor*
* Cooperative Institute for Research in Environmental Sciences, University of Colorado-Boulder.
Boulder. CO 80309
# N'OAAAsRL/Eavirunmcntal Technology Laboratory. Boulder. CO 80303
ABSTRACT
Lidar systems measuring ozone concentration and aerosol profiles in the lower
troposphere can make significant contributions to the understanding of chemical and transport
processes for regional air quality assessment and control The Environmental Technology
Laboratory of the National Oceanic and Atmospheric Administration has developed a
compact, efficient, transportable lower troposphere ozone lidar, which is capable of
continuously measuring ozone concentration profiles from near the surface to about 3 km with
high range resolution, and aerosol backscaiter profiles from near the surface to about 10 km.
The ozone lidar was deployed in two field experiments in California in 1993. The second
field experiment, discussed here, was the Free Radical Study in the Los Angeles basin duiing
September 1993. The ETL Mobile Profiling System (MPS), co-located with the lidar during
the study, continuously measured surface and profiles of meteorological parameters using
remote find in-situ techniques The meteorological information is combined with the ozone
lidar measurements to provide valuable insight into the complexity of the ozone profiles.
INTRODI'f'TION
The Los Angeles Free-Radical Study (LAFRS) (3 Sept.- 22 Sept. 1993) was co-
sponsored by EPA and the California Air Resources Board to study the formation of ozone
(Oj) in the I.os Angeles basin. During the experiment, the multi-wavelength ETL ozone lidar
measured ozone profiles and aerosol profiles, while the MPS provided meteorological support
for the air chemistry portion of the study and meteorological data for input to air pollution
models and comparison with the co-locatcd ozone lidar. Operations were conducted in
Claremont, California, 5 km south of the San Gabriel Mountains and 20 km east of downtown
Los Angeles, a major source region for precursors to Ot. The experiment site was located on
the eastern edge of the Los Angeles basin, some 60 km from the coast.
i Hi: I>irFKRLNTIAL AliSORPTION IJDAR SYSTEM (DIAL)
The compact, transportable differential absorption lidar (DIAL), specifically designed
for ozone and aerosol profiling in the lower troposphere (from near surface to about 3 km),
was developed at the National Oceanic and Atmospheric Administration's Environmental
Technology Laboratory (ETL), formerly Wave Propagation Laboratmy (WPL). The ETL
ozone lidar (Zhao ft al, 1993) transmits four wavelengths simultaneously. Two UV
wavelcnths at 266 and 289 nm are used for ozone profiling from ~I00 m to ~3 km above the
-------
surface with high range resolution. Another two wavelengths at 532 and 266 nm are for
aerosol profiling from the surface to about 10 km. The maximum detection range for ozone
is comparable to or greater than much bigger and more powerful lower tropospheric ozone
lidar systems. The near range coverage is unique (Zhao ct al, 1992), The efficiency and the
compactness of the lidar due to the innovative hardware design and improved signal
processing technique (Zhao, 1990) make the system inexpensive and easily transportable.
A block diagram of the ozone lidar is shown in Fig. 1. The transmitter and the
receiver are assembled on an optical breadboard 1.65 m long and 0.75 m wide The height of
the transmitter and receiver are about 0.6 ni. The optical layout of the transmitter is shown in
Fig. 2 A Continuum Nd:YAG laser (Model NY61-10) is used in the transmitter. The 10-Hz
Nd:YAG laser is frequency-doubled (532 nm) and quadrupled (266 nm) and exits the output
aperture as a single, three-color beam. The output energy at 266 nm is adjusted to be much
lower than the maximum output (within the range of 20 to 40 mJ) to save the down-stream
optics. The energy at 289 nm, which is generated from the residual energy at 532 nm using
Raman shift and sum-frequency-mixing techniques, is in the range of 0.5-4 mJ. The two UV
beams are adjusted to be collineai with an angle difference less than 50 larad. This angle is
further reduced by a 3X beam expander to less than 17 ^rad. The receiver consists of a well-
baffled Newtonian telescope with an 8 inch diameter off-axis parabolic primary mirror and a
field of view of 1.0 mrad. The output beam of the telescope is then directed into a four-
wavelength detector package. The transmitted beams are precisely aligned to the receiver
using lateral transfer retroreflectors and periscopes to an accuracy of better than ±50 prad.
Calibration of the system is carried out in the horizontal direction during periods when the
atmosphere is assumed to be horizontally homogeneous.
At present, a temporary data acquisition and processing system based on an IBM-486
personal computer is employed. Lidar signals at 532 and 1064 nm are digitized by a Iwo-
channel. 8-bit, 64 MHz digitizer, and the UV signals are digitized by a two-channel, 12-bit,
10 MHz digitizer.
The lidar is installed in a mobile laboratory, modified from a 20-foot sea-container.
Thus the lidar is easily transportable. A movable temporary scanning mirror set can be
installed on top of the sea-container to steer the beams in the horizontal direction (with a
±15° scanning capability) for horizontal and low-elevation observations and system
calibrations. The system will be modified to include a full scanning capability within the
next few years.
MOBILE PROFILER SYSTEM
The System Demonstration and Integration Division of the National Oceanic and
Atmospheric Administration's (NOAA) Environmental Technology Laboratory (ETL)
(Boukter, CO) in conjunction with the Battlefield Environment Directorate of the U.S. Army
Research Laboratory (ARL) (White Sands Missile Range, KM) designed and built the Mobile
Profiler System (MPS, Moran and Weber 1993, Wolfe et al. 1994). The purpose of MPS is
to supplement existing rawinsonde data and improve thermodynamic and wind profiles with
nearly continuous integrated data from an array of ground-based and satellite-borne sensors.
-------
The MI'S sensors include a 924-MHz phased-array wind and temperature profiler, a four-
channel microwave radiometer, a surface meteorological tower and a satellite receiving station
for processing satellite radiometer data. Data can be displayed or analyzed from each
instrument separately or as blended thermodynamic and wind profiles. Some technological
advances incorporated in MPS include improved methods of wind profiler and RASS
sampling and processing and near real-time wind profiler quality control (Weber et al. 1992).
JOINT OBSERVATIONS OK THE OZONE LIDAR ANI) HIE MPS IN THE I,APRS
EXPERIMENT
The ozone lidar, the MPS, and other instruments were co-located at a site (elevation 433 m
MSL) approximately 60 km east of downtown Los Angeles, in Claremont, California. During
the experiment period, we experienced the highest surface ozone episode observed during
1993 in the Los Angeles basin. A series of ozone profiles taken during the highest ozone
day, 9/9/93, are shown in Figs. 3a-3f. Atmospheric backscatter profiles at 532 nm are shown
in Figs 4a-4f. Balloon soundings of temperature and humidity profiles are shown in Figs. 5a-
5d. The lidar observations confirm that both ozone and aerosol distributions are significantly
affected by the meterological conditions.
Keith (1980) describes climatological conditions typically found within the Los
Angeles basin. The basin is characterized by a marine air influence and temperature
inversion, especially during the hot summer months. Strong diurnal heating generates a
consistent land/sea breeze. On-shore flow from the Pacific ocean is modified as it moves
inland toward the experiment site. Therefore, the strength of the marine inversion is highly
dependent on the strength and duration of the westerly winds The westerly sea breeze
increases in strength toward mid-afternoon to around 4-6 ms'.
Previous studies (Roberts and Main, 1993) have shown that high concentrations of O,
often exist aloft. Mechanisms for this include undercutting of the mixed layer by the sea
breeze, slope flows along the mountains and their resulting return flow back toward and over
the LA basin, and penetration of low-level polluted air into the inversion layer. Urban
Airshed Models (UAM) have experienced difficulty in modeling these conditions due to the
complexity of these patterns. The MPS and the 03 lidar present a unique opportunity to
observe the atmospheric structure and 0, profile simultaneously, with temporal and spatial
resolution providing a better description of these processes than conceivable in the past.
Figure 6 is a time series of 30-min average wind directions at three heights observed
during a high pollution day as part of LAFRS (9 September 1993). Not shown is the height
of the marine inversion or the mixing depth. The inversion, as monitored continuously by
profller/RASS and confirmed by balloon launches, is shallow and surface-based, extending to
a height of 0.6 km. Surface heating lifts the base of the inversion, but is not able to
completely break through the shallow strong inversion. Early morning surface winds are from
the north-northeast, consistent with a drainage off the San Gabriel mountains. As local
heating begins, the winds first shift to the the southeast before becoming westerly. Wind
speeds are light during this transition period. Winds above the surface (0.2 km), but below
the inversion, exhibit a more easterly component corresponding to the larger scale land
543
-------
breeze. This air appears to be riding over the colder local drainage off the mountains. Wind
directions above the inversion (0.5 km) are consistent with those at 0.2 km, except for an
earlier and more rapid shift from the easterly land breeze to a westerly sea breeze .
Figure 7 is a time series of the measured surface O, and the low-level peak in O,
taken from the profiles observed by the lidar for the same time period as Fig. 6. This peak
varied in height from 0.15 km to 0.35 km beginning just after sunrise. Absolute values of the
lidar profile have not been aerosol corrected at this time. In Fig. 7 we see that the low-level
peak in O, has an early morning maximum corresponding in time with the winds, below the
inversion, shift in response to the inland heating. This maximum is believed to be transported
03 trapped within the inversion layer. Surface O, is also rising at this time, but in a slower
and steadier fashion consistent with local production. We start to see surface 0, levels reflect
the vertical mixing, represented by a slight decrease in 0„ and the transport of higher levels
of 03 from the downtown Los Angeles area as the mixed layer grows and the winds become
more westerly. Upper-level O, shows a similar pattern, but can not be fully explained by the
winds. The mid-morning (1800 UTC) minimum is possibly the result of relatively clean air,
cut-off from the surface, transported from Los Angeles. As heating increases the mixing
depth over Los Angeles, 03 is carried aloft and detected by the lidar as it advects downwind.
This would explain why the elevated O, so closely follows the trend in O, at the surface.
This analysis is for only one day with strong local heating and a well defined land/sea breeze,
but similar data sets can be used to examine other days during LAFRS with different wind
patterns and vertical mixing.
SUMMARY
As can be seen from the comparison for a single day during LAFRS, the complexity
of the region and its meteorology increases the possible pollution scenarios. Further analysis
is needed to obtain a better understanding of the transport of O, within, into, and out of the
Los Angeles basin, especially because of the correlation seen between changes in both surface
and elevated O, levels and wind direction. The role vertical stability plays also needs to be
examined further through use of the continuous RASS temperature profiles. The 0;, lidar and
MPS together should lead to a better understanding of the mechanisms involved.
ACKNOWLEDGEMENT
The joint ozone lidar - MPS observations in the LAFRS were supported by the
California Resources Board (CARB). The authors wish to thank Robert Weber, Dick Cupp,
and Judy Schrocder for their hard work in participation of the experiment, and to Bart Crocs,
Lowell Ashbaugh, and Ash Lashgari of CARB for their encouragement and help.
REFERENCES
Keith, R.W., 1980: A climatological/air quality profile; California south coast air basin. Air
Programs Division Report, F.l Monte, CA, 165 pp.
544
-------
Moran, K.P , and B.I,. Weber, 1993: The Mobile Profiler System: A transportable integrated
sounding system for measuring atmospheric parameters. Preprint: Twenty-sixth Internationa!
Conf. on Radar Meteorology, Norman, OK, 24-28 May 1993, Amer. Meteor Soc , 637-639.
Roberts, P.T. and H.H. Main, 1993: Ozone and particulate matter case study anaylses for the
souther California air quality study. Final Report prepared for South Coast Air Quality
District by Sonoma Technology Inc.
Weber, B.L, and D.B. Wuertz, 1991'. Quality control algorithm for profiler measurements of
winds and temperatures. NOAA Technical Memorandum ERL WPI.-212, NOAA
Environmental Research Laboratories, Boulder CO 32 pp.
Wolfe. D„ B. Weber, D. Wuertz, D. Welsh, D. Merritt, S King, R Fritz, K. Moran, M.
Simon, Anthony S., J. Cogan, D. Littell, and E. Measure, 1994: An Overview of the Mobile
Profiler System: Preliminary Results from Field Tests during the Los Angeles Free-Radical
Study (in review).
Yanzeng Zhao. James N. Howell, and R. Michael Ilardesty, "Transportable Lidar for the
Measurement of Ozone Concentration and Aerosol Profiles in the Lower Troposphere,"
A&WMA/SPIE International Symposium on Optical Sensing for Environmental Monitoring,
October 11-14, 1993, Atlanta, Georgia. (Will be published in SPIE Proceedings Vol. 2112)
Yanzeng Zhao. R. Michael Hardesty, and M. J. Post, "A Multibeam Transmitter for Signal
Dynamic Range Reduction in Incoherent Lidai Systems," Appl. Opt. 31 7623-7632 (1992).
Yanzeng Zhao, "Numerical Differentiation Methods for Estimating Ozone Concentration in
DTAI, Measurements," 1990 Technical Digest Series, Volume 4, pp. 388-391, Optical Remote
Sensing of the Atmosphere, February 12-15, 1990, Incline Village, Nevada.
-------
BLOCK DIAGRAM OF THE OZONE LIDAR i
TRANSMITTER
RECEIVER
206/2 39 &3^
S32M0S4
g
266/289 #1 .
' STEERING
j N'IRRO'-i
: SET
I n'C VERT.CAJ
Fig. 1
OPTICAL LAYOUT OF THE OZONE LIDAR TRANSMITTER
C6i.
SJZ ^ ..
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549
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550
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Fourier Transform Microwave Spectroscopy:
A Potential New Analytical Tool For Trace Gas Species
R. D. Sucnrain, F. J. Lovas, aud R. L. Sains
National Institute of Standards and Technology
Gaithersburg, Maryland 20899
ABSTRACT
A pulsed molecular beam Fabry-Perot microwave spectrometer has been developed that has
demonstrated sensitivities to most polar gas phase molecular species that are in the low parts-per
billion (ppb) range. The highest sensitivity is obtained using neon or argon carrier gas but nitrogen
or air can also be used with some loss in sensitivity due to the less efficient cooling in the molecular
beam with diatomic gases. The minimum detectable concentrations for several representative
compounds has been determined. These include S02, propene, acrolein, and methyl t-butyl ether.
Considerable attention has been given to making the instrument robust for use in industrial
laboratories. The instrument is controlled using a standard Intel 486 based computer. A Graphical
User Interface (Windows-type) operating system has been developed that makes the instrument
extremely user-friendly allowing all instrument control functions to be carried out using a mouse.
INTRODUCTION
The technique of Fourier transform microwave spectroscopy (FTMS) was pioneered in the
late 1970's and early 1980's by Balle and Flygare1. Our first instrument at NIST was constructed
in 19852. Since that time many improvements have been made to this instrument, some of which
have been previously described3. These new improvements have increased the sensitivity of the
instrument as well as made it much easier to use. A software package has been developed that
allows all instrument control functions to be accomplished using a standard computer mouse.
I'.XPKRIYI KNTAI.
Instrument
A block diagram of the instrument is shown in Figure 1. The instrument consists of a
Fabry-Perot microwave cavity formed by two diamond-turned aluminum mirrors that are 35 cm in
diameter, 'llie mirrors are housed in a vacuum chamber that is approximately 1 m in length and
60 cm in diameter. The vacuum chamber is pumped by an 8000 l/s diffusion pump and a
2.5 nr'/'min roughing pump. A commercial pulsed molecular beam valve has been modified with
two 1.5 mm inlet lines that allow gas to enter the valve near the valve tip. The flow through these
inlet lines is controlled by mass flow controllers. Excess gas flows out the top of the pulsed valve
allowing a continuous fresh sample at the nozzle tip. In a typical experiment the gas to be analyzed
is entrained at low concentration levels (up to several %) in an inert carrier gas stream such as air,
nitrogen, neon or argon. The expansion of the gas from the high pressure side of the nozzle into
the vacuum chamber cools the molecules in the gas pulse to near 1 K. At this temperature only the
lowest few rotational energy levels of the molecules are populated. Thus by probing rotational
transitions from these low lying energy levels, a tremendous increase in signal to noise is obtained
compared to a room temperature sample. This enables one to study larger gas phase species with
complex rotational spectra with the ease that one usually associates only with light diatomic and
triatomic species.
The pulsed valve can be mounted to pulse either perpendicular lo the Fabry-Perot cavity or
collinear with the cavity axis. For the results reported here, the valve was mounted on the back
side of one of the Fabry-Perot cavity mirrors and pulses the gas through a 1 mm diameter hole
-------
through the mirror parallel to the cavity axis. The positions of both mirrors are controlled with
computer-driven motor micrometers. The microwave radiation enters the cavity through a L-shapcd
coaxial antenna located at the center of the mirror.
Microwave radiation from a microwave synthesizer is synchronously pulsed into the
microwave cavity by opening a microwave switch for a short time (1-5 y.sec) when the molecule.fi
from the nozzle are in the cavity. This generates Fourier components of the microwave radiation
that cover ~ 1 MHz in bandwidth. If the molecules in the molecular beam have a rotational
transition within the bandwidth of the cavity they are "pumped" by the Fourier components of the
microwave radiation that has been pulsed into the cavity. After a few microseconds of delay, the
molecular emission signal from the cavity is digitized for several hundred microseconds as the
molecules that were pumped by the original microwave pulse relax back to their original state.
Once the decay signal has been stored in the computer it can then be Fourier transformed into the
frequency domain. This entire process can be repeated at 2-10 Hz for signal averaging or real-tiirie
monitoring of polar trace-gas species. A typical Fourier transformed signal is shown in Figure 2.
The two Doppler components of the signal arise because the molecular beam is traveling in one
direction down the cavity axis while the microwave radiation is traversing the cavity in both
directions, thus generating a forward and reverse Doppler component of the molecular signal. The
true rotational frequency is the average of the two frequency components.
Sample Preparation
Initial tests have been performed with several compounds in order to assess the minimum
detectable concentration for each molecular species. In these tests, identical samples were prepared
by Filling aluminum cylinders with approximately 533 Pa [4 torr] of the gas of interest. The
cylinders were then pressurized to 0.65 MPa |80psiJ which makes the final concentration
approximately 816 pprn. In most cases this sample concentration provides signals that are too
intense to be measured accurately. In order to determine the Minimum Detectable Signal (MDS) for
each species, rotational transitions from some of the less abundant naturally-occurring isotopes were
recorded. The natural abundances of the various isotopic species are given in Table I. These rare
isotopes provide a built-in measure of relative intensities that spans several orders of magnitude.
The. only restriction is that an isotopic species has been previously studied so that the frequencies of
the transitions are known.
Since some variation in rotational transition strength with carrier gas is expected, three
identical samples were usually prepared. Samples were prepared using neon, argon, ar.d nitrogen as
the inert carrier gas. The most intense signals are obtained using neon, followed by argon and then
nitrogen. Indications are that neon provides good cooling and very little complexation while argon
provides good cooling but it also tends to form more bintolecular complexes with the sample of
interest. Nitrogen does not cool as well as the monatomic gases and hence provides the weakest
molecular signals. The signal strength in nitrogen typically is a factor of ten weaker than in neon.
Variation of signal strength is shown in Figure 3 where the same rotational transition of a 13(:
isotopomer of acrolein (8.6 ppm) is shown for the three different carrier gases.
Figure 4. shows a rotational transition of one of the deuterated isotopomers of acrolein in
neon which is present in natural abundance in the 816 ppm sample at 122 ppb. The upper trace
shows the results of one gas pulse from the nozzle while the lower trace shows the results of
averaging 100 gas pulses (50 seconds of integration). The signal-to-noise ratio improves as the
square root of the number of pulses so the lower trace should be a factor of ten better than the upper
trace-
Sulfur Dioxide Experiments
Sulfur dioxide is a common emission product in many combustion processes. Its rotational
spectrum is rather sparse in the spectral region accessible by the current FTMS thus, the only
transition that can be monitored is the 202 In transition in the vicinity of 12 GHz. Unfortunately
552
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ihis transition is approximately 60 GHz higher in energy than the lowest energy transition. Thus in
the cold molecular beam, the lower state is not well populated. However, the signals are still
reasonably intense and good sensitivities can be obtained. A number of Standard Reference Gas
samples of SO-> in nitrogen are available from NIST as Standard Reference Materials (SRMs).
Several of these samples were used to assess the linearity of response of the instrument. SRMs of
approximately 50, 500 and 1000 ppm of S02 in nitrogen were used to obtain the data in Figure 5.
A least squares fit of the three data points indicates that the instrument response is linear over more
than an order of magnitude in signal strength. Currently, an 8-bit digitizing board is being used,
however, installation of a 12-bit digitizer would greatly extend the linear range of the instrument.
The signal indicated at 360 ppm is a sample that was prepared to test the gas variation (Ne, Ar, and
N2). This illustrates how the instrument can be calibrated using SRM samples.
Carrier Gas Blending
A set of experiments was carried out using the J = 1 «- 0 rotational transition of carbonyl
sulphide (OCS) 10 see if blending varying amounts of Ne or Ar could be used to enhance the signal
strength of a sample in a nitrogen carrier gas stream which would be the typical carrier gas in most
industrial process streams. In these experiments, commercial mass flow controllers were used to
blend the gases in our flow nozzle. Figure 6 shows that an increase in signal strength is obtained by
blending up to approximately 50% Ne or Ar. In this plot, the normalized signal intensity (/iV/ppm)
is plotted vs the % of inert gas added to the total carrier gas stream. With Ne, an order of
magnitude increase is obtained while with argon only a factor of five is realized. It is not certain
why the signal intensity drops after the addition of 50% inert gas but it may be due to inefficient
mixing of the two gases at the. nozzle tip. The important point however is that the signal strength
can be increased by an order of magnitude just by diluting with neon carrier gas.
Searching for Unknown Molecular Species
The software package available with our instrument allows completely automated, unattended
searching with the instrument. This is advantageous if unknown chemical species are present in the
process gas stream. Of course if certain molecular species are expected it is quite simple to just
program the computer to quickly jump between a given set of frequencies to check for any number
of different compounds.
CONCLUSIONS
Table II lists several compounds that have been studied to determine the minimum detectable
signal for each species. All of the compounds studied to the present time have detection limits that
are in the low 10 mid ppb region when neon carrier gas is used and 100 gas pulses are averaged.
This list is currently being expanded to include a number of different classes of compounds.
Additional improvements to the software and hardware of the instrument should allow us to realize
another order-of-rnagnitude improvement in sensitivity of the instrument.
In addition to the real-time analysis capability of the instrument, all the standard water
management and concentration techniques commonly used in gas chromatographic-mass
spectrometry applications can also be employed with the FTMS method, thus, easily extending the
minimum detectable signals down into the parts-per-trillion region. The high sensitivity of the FTMS
technique coupled with the 100% species selectivity should make it an attractive procedure that
could be used in a variety of process monitoring and control situations as well as a competitive
extractive stack-gas sampling technique for trace gas analysts.
553
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REFERENCES
1. Balle, T.J. and Flygare. W.A. Rev. Sci. Instrum. 1981 52, 33-45.
2. l.ovas, F.J. and Suenram, R.I). J. ClherrL Phys. 1987 87. 2010-2020.
3. Suenram, R.D.. Lovas. F.J., Fraser, G.T.. Gillies, J.Z., Gillies. C.W.. and Onda, M.,
LMaLSpcgtrosc, 1989122. 127-137.
554
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Table t. Natural abundance of a number of the isotopic species.
Isotopic species !
% Natural abundance.8
Concentration, (ppm)
l60
99.76
816
18o
0.2
1,63
170
0.04
0.333
12c
98,89
816
13c
1,11
9.090
!h
99.99
816
3h
0.015
0.122
a. The natural abundance is relative to each individual atom, ie 0, C, and H.
Table II. Minimum deteteetable signals in the FTMS instrument for several molecular
species.
Compound
Formula
MDSa (ppb)
Acrolein
iI2C=CHCHO
3
Sulfur Dioxide
S02
13
Propionaldehyde
CH3CH2CHO
100
Methyl t-Butyl ether
CH3OC(CH3)3
190
Propene
ch3ch=ch2
250
Minimum Detectable Signal for the following set of parameters: Neon carrier gas;
average of 100 gas pulses taken at a 2 Hz repetition rate (50 sec total integration time)
assuming a signal-to-noise ratio of 1.
555
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556
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ACROLEIN 1 C i - SHOT
8.6 ppm
0 R9
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FREQUENCY IN MHz
Figure 3. Frequency domain spectra of a 13c isotopomer of acrolein showing
the signal, intensity variation with carrier gas Cone gas pulse in
each case).
558
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Figure 4. Frequency domain spectrum of a deuterated isotopomer of acrolein in
natural abundance (120 ppb). This figure shows the signal-to-noise
improvement obtained with averaging.
S59
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Figure 5. A plot of signal strength versus S02 concentration obtained using
three different NIST SRHs, The 360 ppn plot indicates how the plot
was used to determine the concentration of an unknown sample.
560
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Monitoring Air Pollutants by Molecular Iteam Microwave Spectroscopy
U. Andrcsen, U. Kretschmer, C. Thomscn, and H. Dri'.izler
Abicilung Chemisette Physik im Institut 1'iir Physikalische ("hemic dcr Univcrsitat Kiel
24098 Kiel, Germany
The molecular beam Fourier transform microwave spectroscopy has been
proved to be a very powerful tool to determine molecular parameters in the gas phase
with high precision and high resolution. It will be shown that this method is also
suitable for quantitative analysis, this means the e%'aluation of concentration ol single
components in complex gas mixtures like pollutants in air.
Microwave spectroscopy is mainly restricted to the investigation of polar
molecules. Many industrial solvents, chloroflunromethancs or oilier air pollutants
belong to this group of substances. Presently about 2000 molecules have been
analyz.cd and their parameters published. Many of these gases may be monitored with
only one instrument. To switch from one substance to another takes about one minute.
Due to the high resolution of the apparatus there is nearly no cross
sensitivity. The usable range of concentration is from percent to the lower ppm at
least, but may be lower depending on the gas. The total measuring time ranges Iioni
seconds lo minutes depending on concentration and substance.
The method and the apparatus will be presented and some features of
instrument will be discussed.
562
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The Effect of Temperature on the Ability to Collect Data:
The MDA Scientific Open-Path Fourier Transform Infrared Spectrometer
Judith O. Zwicker, PhD
William M. Vaughan, PhD
Remote SensingsAir, Inc.
8147 Delmar Blvd., Suite 219
St. Louis, MO 63130
and
George Russwurm, PhD
ManTech Environmental Technology, Ine.
P.O. Box 12313
Research Triangle Park, NC 27709
ABSTRACT
The experience of several users of the MDA Scientific, Inc. open-path Fourier Transform
Infrared spectrometer has shown that the system has difficulty collecting data at low
lcm|)eratures. especially when the instrument is subjected to long periods at low temperatures
when the instrument is not turned on. The interferometer needs to be sufficiently warm to find
its zero point before data collection can begin. Since delays in data collection can result in
costly delays in beginning operations at a clean-up site or loss of data for an industrial study, it
is important to understand the parameters of the temperature effects and how to reduce their
effect on delays in data collection. For this reason, Remote Sensing^Air, Inc. (RS=A) decided
to test its instrument under varying temperature regimes to document the temperature at which
the instrument would begin collecting data and the best ways to attain that temperature to
avoid unnecessary delays. The instrument was set up in an unheated area of a basement and
the ambient temperature and the temperature of the instrument below the interferometer were
collected and recorded every minute.
Data are presented showing the temperature at which the instrument begins collecting
data, the increase in final equilibrium temperature due to operation of the instrument, to
adding heating pads, and to adding insulation. These data should help determine which means
of increasing the temperature will be effective under various low temperature regimes.
Coincident with the RS=A study, a group at ManTech Environmental Technologies, Inc.
(ManTcch) performed a similar test with their MDA system with very similar results. The
results of both studies are presented.
It should be noted that other OP-FTIR instruments may also have trouble collecting data
when cold; however, MDA Scientific instruments were available for the two studies reported.
INTRODUCTION
Open-path optical remote sensing has been used very successfully over the last several
years in monitoring air quality at industrial facilities1'514 and at hazardous waste sites.'
During such monitoring programs, it has been noted that there is difficulty in collecting data
with the MDA Scientific open-path spectrophotometer at low ambient temperatures especially
when the instrument has been exposed to these low temperatures while the instrument i> not
563
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turned on. Since delays in data collection can result in costly delay? in beginning operations at
a clean-up site or loss of data for an industrial study, it is important to understand the
parameters affecting the influence of temperature on data collection and how to reduce delays
in data collection. For this reason, Remote Sensing=Air, Inc. (RS = A) decided to test its
instrument under varying temperature regimes to document the temperature at which the
instrument would begin collecting data and the best ways to attain that temperature, thus,
avoiding unnecessary delays.
METHODS AN1) MEASUREMENTS
Both the RS=A and ManTech studies used MDA open-path spectrometers and a means of
determining the ambient and instrument temperatures simultaneously. The RS = A OP-FUR
system has the detector cooled using a Stirling engine while the ManTech system uses liquid
nitrogen for cooling the detector.
RSsA Study
Purpose and Goals
The purpose of the study was to gain an understanding of the parameters involved in
determining the time that it would take for the system to begin collecting data under various
temperature regimes. The goals were:
• To be able to predict how long it would take the OP-FUR to start collecting data
under various low temperature regimes.
• To be able to control the time needed to initiate data collection (i.e. shorten it)
through the use of insulation and/or heating devices.
The following questions were to be answered by the study:
• At what temperature does the instrument begin collecting data under various cold
temperature regimes?
• What is the increase in final equilibrium temperature provided by having the
instrument on?
• What is the increase in final equilibrium temperature provided by using insulation
with the instrument on?
• What is the increase in final equilibrium temperature provided by using a heating
pad?
• How long does it take for the instrument to reach the temperature required for
collecting data under various cold temperature regimes?
• Once collecting data, will the instrument continue to collect even if the temperature
drops?
Temperature Determinations
Temperatures were monitored continuously using a DataBear® datalogger and sensors
(LPT# 1400) using the Sense-Your-World!®' software (Laugan Products, Inc.) for transfer of
data to RS = A's analytical programs. The DataBear® datalogger allows simultaneous collection
of temperature data at two locations with the data determined each second and saved at
564
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interval* from one second to a maximum of 32767 seconds. Temperatures were also
determined using a standard thermocouple voltmeter and from Radio Shack. Temperature data
were collected 24 hours per day except when dumping the data. The usual interval was every
10 minutes.
OP-FT1R System and Set-up
The RS = A open-path FT1R instrument studied was a MDA Scientific, Inc. open-path
I-TIR (model 282(NK>) with a Stirling engine cooler for the detector. The system was configured
in the unistatic mode using a 35 cm x 35 cm retroreflector. Data were collected using the
continuous monitor application developed by MDA. This application made it possible to
determine exactly when data collection began by recording the time of the spectra collected.
The instrument was set up in an unheated and poorly insulated area nf a basement during a
very cold time in St. Louis (January 1094). The path-length was necessarily short due to space
restrictions: the path length varied from 7 m to 3 m during the study. Data collection times
varied between five minutes and one hour. The computer was set up in a warmer section of
the basement and connected to the spectrometer with 250 meters of fiber optic cable.
ManTech Study
Purpose and Goals
The ManTech data reported here are part of a larger, on-going study to develop a
database of information on data collected over a Jong time span in one location. In addition to
the spectra collected, operating parameters related to the data collection were also collected.
These operating parameters included instrument and ambient temperature data.
Temperature Determinations
Temperatures were determined simultaneously inside the OP-FTIR instrument, in the
shack in which the OP-FTIR was housed, and the outside of the shack using a Rustrack Ranger
11® datalogger with three probes (National Instrument LM35CZ). The ambient relative
humidity was also monitored and logged using the datalogger. One of the temperature probes
was inserted inside the instrument and hung just above the interferometer while the top of the
OP-FTIR instrument was left unsealed. Temperature data were collected every minutes 24
hours each day.
OP-FTIR System and Set-up
The MDA Scientific system used by ManTech was similar to that used by KS = A: however,
the ManTech unit used liquid nitrogen for cooling the detector rather than the Stirling cooler
used by the RS^A unit. Also, because the ManTech unit is opened frequently, it is not under
constant nitrogen pressure as the RS=A unit is.
The ManTecii OP-FTIR system was set up in a shack at one end of an open field near the
EPA complex with the retroreflector on a tower at the other end of the field. The shack was
heated and was kept closed at night (5 pm to 8 am) and opened each morning to allow the OP-
FTIR beam to access the retroreflector. The instrument was left on over night but was not
collecting data. Data collection occurred from 8 am to 5 pm except for special overnight
studies not reported in this paper.
DATA ANALYSIS AND RESULTS
Both the RS=A and ManTech data from the respective dataloggers (temperature, date and
lime) were transferred to QuattroPro® for graphing and analysis. The difference in the
temperature between the ambient air and either under the interferometer (RS A) or above the
565
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interferometer inside of the instrument (ManTech) was determined for each data set. For the
RS = A data, the time of increase and final temperature difference when the instrument was
turned on, when the heating pads were turned on, and when insulation was used was
determined for each data set. These data were used to answer the questions posed above and
presented in the Conclusions and Recommendations section of this paper.
Temperature of Start of Data Collection
In order to determine the temperature at which the instrument would begin data
collection, the instrument was turned off at night and left in the cold area of the basement.
Sometimes the instrument was turned off but with insulation and/or the heating pad on. The
instrument was turned on in the morning and the Continuous Monitor software started. The set
up could then he left unattended and the spectra and concentration data were automatically
saved as data began to be collected. Plots of data from three days of monitoring are shown in
Figures 1 - 3. A time series plot of temperature of first data collection and ambient
temperature is presented in Figure. 4. As can be seen, the temperature under the instrument at
which the instrument begins collecting data is very consistent even at widely different ambient
temperatures. The time to reach that temperature does vary with ambient temperatures and
whether the instrument is heated and/or insulated. Since the ManTech instrument was usually
left on all of the time and kept in a heated shack during the night, there was usually no
problem in initiating data collection. However, on a few occasions they encountered similar
problems with initiating data collection at low temperatures.
Once the instrument began collecting data, the temperature could drop significantly and
data would still be collected (see Figures 5 and 6). Neither the RShA group nor the ManTech
group observed any differences or problems with data collected at low temperatures (below
those at which data collections could be initiated).
Increase in Final Equilibrium Temperature Provided bv the Instrument Running
The increase in final equilibrium temperature provided by the heat produced by having the
instrument turned on can be seen in Figures 2, 3, and 5 for the RS^A study and Figures 0 and
7 for the ManTech Study. The ManTech data indicate a slightly higher difference than the
RS = A data. This higher difference is likely due to the positioning of the probe inside of the
instrument rather than having it taped to the outside as done for the RS = A study. The 10 to
12 °C increase due to having the instrument on is usually enough to allow data collection under
cool but not cold conditions. Again, the plots show that the final difference, appears to be
independent of the ambient conditions.
Increase in Final Bquilibrium Temperature Provided bv External Heating_and Use of Insulation
The temperature of the instrument was significantly increased by the use of heating pads
attached under the instrument just below the interferometer. The rate of increase observed by
the RS^- A group may be misleading since the heating pad and probe were both attached under
the interferometer and the probe (even though separated from the heating pad by styrofonm)
was likely to have been affected more quickly than the interior of the instrument. Figures 1 -3
indicate the effects of the heating pads and/or insulation.
The temperature at which data collection occurs and the final temperature rise for various
heating and insulation scenarios do not depend on the ambient temperatures. Flowever, the
rate of rise and, thus, the time before data can be collected does appear to depend on the
ambient temperature. Because the RSsA probe was not inside the instrument, the rates
determined are probably skewed toward faster rates for external heating. At ambient
temperatures from -10 to (FC it took between 3 and 5 hours to start data collection with both
the iastrument and heating pad on.
566
-------
CONCLUSIONS AND RECOMMENDATIONS
It is concluded that there are several ways of ensuring that the instrument will be at the
proper temperature for data collection and that it is useful to understand the capabilities of
each. The answers to the questions posed at the beginning of the paper are presented below.
Answers to Questions
• The RS^A OP-FTIR instrument began collecting data at approximately 22 °C (72 °F)
with an standard deviation of 2 °C. The variation appears to be due to the variation
in the location of the taping of the probe under the instrument or possibly the slipping
of the stvrofoam placed between the probe and the heating pad.
• The increase in final equilibrium temperature provided by having the instrument on
was 10 °C (50 °F) with an uncertainty of 2 UC for the RS=A study. For the ManTech
study, the increase was 12 °C (54 "F) with an uncertainty of 0.5 "C for the April 11
data with slight changes in ambient temperature and an uncertainty of 4 °C for the
January 19 data with large changes in ambient temperature.
• A cotton cover provided a final equilibrium temperature increase of 5 "C (41 "F).
Insulation with aluminum foil next to the instrument, a layer of foam rubber and a
wool blanket provided a final equilibrium temperature increase of 12 °C.
• The heating pad provided a temperature rise of 10 to 15 °C (50 to 59 °F) depending
on whether set at medium or high.
• A minimum of four hours should be allowed for the instrument to warm up if it has
been left turned off and equilibrated at temperatures below 10 °G.
• There was no indication in the data collected in either the RS = A or the ManTech
study of any differences or problems with the spectra collected at temperatures below
that needed to initiate data collection once data collection had begun.
Solutions to Data Collection at Low Temperatures
Below are listed some methods that have been used to allow data collection at low
temperatures.
• If no ac power is available and generators need to be used, keep the iastniment warm
when not being used, turn on the instrument as soon as it is set up and use a heating
pad or hair dryer to warm up the interferometer quickly.
• ManTech keeps their instrument on continuously in a heated shack.
• Blasland, Rouck and Lee, Inc. uses a timer to turn the instrument on several hours
before it is needed, if there is power available. They also use a "jacket" made of
rubber and attached with velcro which has been used for data collection at
temperatures of -29 °C (-20 °F).8
567
-------
REFERENCES
1. Schmidt, C.E. el al., "Use of Optical Remote Sensing and Flux Chamber Technologies
for determining Emission Rates from a Pulp Mill Wastewater Treatment Facility,'
presented at the 87th Annual Meeting and Inhibition of the Air & Waste
Management Association, Cincinnati, Ohio (June 1994).
2. Hendricks, D.M. and Lippcrt, J.I .., "Ambient Air Toxics Measurements by Open-Path
FHR: Results of a Field Trial at the Kodak Park Industrial Complex," presented at
the 87th Annual Meeting and Exhibition of the Air & Waste Management Association,
Cincinnati, Ohio (June 1994).
3. Draves, J.A., Spellicv, R.L.. and Herget, W.F., "Open Path and Extractive Monitoring
of Slack Gases," presented at the 86th Annual Meeting & Exhibition of the Air &
Waste Management Association, Denver, Colorado (June 1993).
4. Phillips, W. and Brandon, R., "FTIR Remote Sensing Data Reduction Technique for
Elevated Temperature Gas Emissions from an Aluminum Smelting Plant," presented
at the 86th Annual Meeting & Exhibition of the Air &. Waste Management
Association, Denver, Colorado (June 1993).
5. Kagann, R.I I. et al, "The Use of an Open-Path FTIR Sensor to Measure VOCs at the
Hanford Site," presented at the 87th Annual Meeting & Exhibition of the Air & Waste
Management Association, Cincinnati, Ohio (June 1994).
6. McCauley, C.L. et al, "FHR Remote Sensing Applications at Municipal Wastewater
Treatment Plants," presented at the 86th Annual Meeting & Exhibition of the Air &
Waste Management Association, Denver, Colorado (June 1993).
7. Kagann, R.II. and Shoop, D.S., "Fourier Transform Infrared Remote Sensor
Measurements of Chemical Emissions at a RCRA Treatment, Storage and Disposal
Facility1," presented at the 85th Annual Meeting & Exhibition of the Air & Waste
Management Association, Kansas City, Missouri (June 1992).
8. D. Pescatore and R. Kricks. Blasland, Bouck & Lee, Inc., Cranbury, NJ, personal
communication, April 1994.
568
-------
RSA TEMPERATURE DEPENDENCE STUDY
10 January 1994
70-
o 60"
g> 50-
a 4oJ
0)
3 30 -j
FraiHrmut S lUtiHIMtBUmJiB-
Heating Pad On " '
- No Insulation On
Q_
-10"
-20—
22 24
Time (CST)
— FTIR Temperature - Ambient Temperature ¦< Insulation On
u FTIR Ori x Heating Pad On ~ Begin Data Collect
Figure 1.
RSsA Study on 10 January 1994 - Temperature of instrument, ambient
temperature, and temperature at which data collections occurred.
-------
RSA TEMPERATURE DEPENDENCE STUDY
11 January 1994
FTIR On
aawMiwat
Heating Pad On
No Cover
12 14 16 18 20
Time (CST)
' FTIR Temperature Ambient Temperature i— FTIR on
i x Heating pad on ~ Begin data collect
Figure 2.
RShA Study on 11 January 1994 - Temperature of instrument, ambient
' • • Ait* ™l|prrions occurred.
-------
.^/1 11— iv11 i_r»M i uric UtrtNUfcNUL SI UDY
13 January 1994
70-
FTIR On ;
inn atfii ii Ji mi ii a ¦ i h :i Him i«wiiii,iii
O
O)
CD
a
Large Heating Pad On High with No Insulation
40-
30-
¦+—»
CD
v_
CD
E 10-
CD
I_ 0"
-10
-20-
Time (CST)
; FTIR Temperature Ambient Temperature c FTIRon
i x Heating Pad On ~ Begin Data Collect
Figure 3.
RS=A Study on 13 January 1994 - Temperature of instrument, ambient
temperature, and temperature at which data collections occurred.
-------
30-
RSA OP-FTIR TEMPERATURE STUDY
Data Collect and Ambient Temperatures
25
20-
O
en 15-
CD ^
Q,
CD
cd
a3
Q.
CD
H
10-1
5i
i
0 r-
-5-:
-10^
~
a
..CL...
*4
~
*6
=*5
CD
yd
-15-
¥ 3 4 5 6 7 8 9
Event
10
Data Collect
Avg. Data Collect x Ambient
I'ioure 4.
KS=A Study - Comparison of the temperature at which the instrument
•• mnfthcRSsA
-------
— uml/uimul. Ol UUI
12 January 1994
O
O)
CD
Q
-------
MANTECH TEMPERATURE COMPARISON
19 January 1994
FTIR on all day
o> 50
Shack opened;
0 2 4 6 8 10 12 14 16 18 20
Time (EST)
Figure 6.
FTIR Temperature
Ambient Temperature
ManTech Study on 19 January 1994 - Temperature of instrument and
ambient temperature. Note that the instrument remained on all night and
day and began collecting data when shack was opened about 7 am and
' ' "' tonmorntiirM below those needed for initiating data
-------
- .i_ wvivii r-\i iiOV/IM
11 April 1994
FTIR on all day
Shack opened
0 2 4 6 8 10 12 14 16 18 20 22 24
Time (EST)
FTIR Temperature Ambient Temperature i
Figure 7. ManTech Study on 1! April 1994 - Temperature of instrument and
ambient temperature. Note that the difference between instrument
temperature and ambient temperature remained steady throughout the day
and the same as on the very cold day (19 January 1994).
-------
PHOTOLYSIS ASSISTED POLLUTION ANALYSIS (PAPA)
Philip L, Hansl
Infrared Analysis. Inc.
11629 Deborah Drive
Potomac. MD 20854
ABSTRACT
Photolysis Assisted Pollution Analysis (PAPA) combines the infrared method of gas
measurement with a boost of high-speed photochemical activity. PAPA goes beyond stardard
infrared absorption techniques by using a compound conversion process that selects reactive gases
from among the non-reactive and reveals their spectra. At the same time the technique renders
invisibe the spectra of water and carbon dioxide. In PAPA, three infrared spectra arc recorded:
the first through an empty absorption cell, the second through the cell containing sample, and
the third through the cell with sample, after photochemical transformation. The photochemical
activity is initiated by ultraviolet radiation from a quartz-mercury lamp. Ozone molecules,
oxygen atoms and hydroxy! radicals are formed. These cause oxidation of the reactive pollutant
molecules. From the three spectra, the computer extracts the concentrations of pollutant gases.
In a single experiment, many gases may be measured. When a ratio plot is made from tlie
second and third spectra, high visibility is conferred on reactants and products. At the same
time, unreactive molecules, including water and carbon dioxide, are allowed to remain invisible.
The unreactive molecules are measured in a ratio plot made from the first and second spectra.
In PAPA, no calibration chemicals arc needed. The calibration comes from the software
package, which contains a library of digitized quantitative reference spectra. The PAPA method
can measure pollutant gases down to paits-pcr-billion concentration levels, including especially:
(1) nitrogen oxides and other nitrogen containing polllutants, (2) organic pollutant gases,
including acids, aldehydes, ethers, esters, ketones, hydrocarbons, and halogenated compounds,
(3) isoprene, pinenes and other reactive hydrocarbons, (4) benzene and other aromatic
compounds, including halogenated species, and (5) hydrogen sulfide, carbon disulfide,
mercaptans and other sulfur-containing pollutants.
576
-------
Introduction
All gaseous polyatomic and heteronuclear diatomic molecules can be measured by their
infrared absorption, but some are more difficult to measure than others Some compounds are
difficult to measure because of weak absorption bands, while others that have strong absorption
bands are difficult to measure because of interference bv water and carbon dioxide. (Ref. i).
The first problem-that of the weak bands-has not yet had much attention. At first
consideration it might appear that not much could be done for improvement. In the past,
compounds with weak bands, such as hydrogen sulfide, have only been measured by infrared
when at relatively high concentrations. We describe here, however, a method of converting
weaklv-absorbing compounds into new compounds that have strong, easily measured infrared
bands.
Hie second and larger problem -that of interference by water and carbon dioxide -has had
much effort devoted to it, but proposed solutions have not been easy to apply. The most used
solution is to ratio the sample spectrum against a reference spectrum of a gas mixture that
contains water and carbon dioxide at the same concentrations as in the sample. Unfortunately,
absorbance law failure at low resolution makes it necessary to use many different reference
spectra to accomodate the wide range of humidities encountered in the air. The compound
conversion sytem we describe here eliminates the need for these spectra. Our new method has
the effect of using the sample itself as its reference mixture.
The PAPA method uses ultraviolet radiation to transform die trace gases in an air sample.
The radiation creates oxygen atoms, ozone molecules and OH radicals, which are then mainly
responsible for the transformation of the pollutant gases. A ratio plot of spectra obtained before
and after transformation reveals (in one direction) the spectra of gases removed and (in the other
direction) the spectra of gases created.
The source of the radiation is a medium-pressure quartz mercury resonance lamp. Tins
type of lamp emits one or two percent of its radiation in the 185 nin. mercury line and about 90
percent in the 254 nm. line, with the remainder in lines that fall in the near ultraviolet and
visible. The 185 nm. photons dissociate oxygen molecules. The resultant oxygen atoms react
mainly with molecular oxygen to form ozone. The ozone can then react with other molecules,
or it can absorb the 254 nin. photons and be photo-dissociated, giving oxygen atoms in the
energetic singlet-D state. These energetic atoms react with water to produce hydroxy! radicals.
The ultraviolet photons can also directly photo-dissociate pollutant molecules. Here are some
577
-------
of the reactions that take place in an air sample.
02 I photon (185 nm) = 20
O -r 0-, (HI) - O- < + M)
O3 : photon (254 nm) = O- i 0!< (singlet-D)
O* - H20 - 20H
0* r HjO = H20,
H202 -t photon(254 nm) = 20H
OH t RH = R ; H20 (RH is any organic compound)
R02 -r NO, -- RO2NO7 (esp when R is acetyl)
03 J- unsaturated hydrocarbons = oxygenated fragments
OH — unsaturated hydrocarbons = oxygenated fragments
Os - NO - N().: + 02
O^ + 2N0? = N-,Oj + Ot
There are nianv possible reactions beyond those shown above. (Ref. 2). It docs not
appear to be practical to try to explain everything that can happen to air pollutants in this case.
The important point is that reactive molecules will be transformed in the air sample, but water
and carbon dioxide will not be transformed. When the before-photolysis spectrum is then
divided by the after-photolysis spectrum, only the changes in sample composition are revealed,
and the water and C02 lines are cancelled out.
Products of the transformation of organic compounds include water and CO, as well as
partiaily-oxidized intermediate compounds. The newly-created water and CO, are unobtrusive
in the spectrum, because they are only a small increment on the large amounts already present.
The most prominent products of the photolysis arc the ozone and hydrogen peroxide, but their
bands can be subtracted out. The ozone-H70-> spectrum needed for the subtraction may be
created through photolysis of a sample of clean air.
Since some important molecules are stable under the photolysis, a full analysis of air will
required examination ot the spectrum before photolysis as well as examination of the ratio of the
before-photolysis and after-photolysis spectra. The amounts of reactants and products may he
determined by the interactive subtraction technique, using digitized quantitative reference spectra.
When the PAPA technique is carried out in a long path absorption cell while using the best of
the infrared detectors, detection sensitivity can extend down to the parts-per-billion level (10"9
atrn.).
578
-------
Components of a PAPA Sy5tg.n1
A PAPA system has three main pans: (1) an FT-1R spectrometer, (2) the PAPA cell, and
(3) the quantitative analysis software. The system used in the present tests and demonstrations
included the following components, as sketched in Figure 1.
(1) A MIDAC scanning interferometer of 0.5 cm"1 resolution.
(2) A Nernst glower source.
(3) A permanently-aligned multiple-pass cell manufactured by Infrared Analysis. Inc. Cell
length was 1.5 meters; inside diameter was 0.15 meters. The optical path was 62 meters.
(4) Two 40-Watt medium pressure quartz mercury lamps mounted inside the cell.
(5) LAB-CALC spectroscopic software.
(G) The iG.ftargd.Aoalyiii.Jnc, library of digitized quantitative reference spectra.
Mukiplc'pass Cell witb
Internal Quartz-ruercurv L^mps
MIDAC
^rfercrnsrer
Figure 1. PAPA System Components.
A Demonstration with Aromatic Hydrocarbons
Benzene and the other gaseous aromatic hydrocarbons are readily measured in PAPA.
This includes halogenated species. Benzene in air is normally difficult to measure because its
strongest band (at 674 cm"1) is hidden by C02 lines. In PAPA, however, the C02 remains
invisible while benzene is revealed by removal of its strong band.
The detection of benzene, toluene and ortho-xylene are illustrated in Figures 8 and 9.
Figure 2. Pathlength was 45 meters. The changes in the spectra due to photolysis are not readily
apparent in the single-beam plots, while in the absorbance-type plot of PAPA, the bands of the
aromatic pollutants are clearly revealed.
579
-------
•\rr «~v>' -'av>
r%
I • t
A
rt f0L Mf) m
V'-'W i'%
Hi1.
I Koom air with aromatics, before ITV jl I i
l|, 'l'*
"WtWlfWWv ! »»wVWw
wn t-
i v.j V i
' r •'¦ a a.
Room air with aromatios, 60 sec,
>k i/1,4h P \ ^
-Av^i vV W; •*!'• 'v1 !
. /^~*S i
Absorbanre-type plot, j j '\ J
' after UV spectrum over ;| 1| . j 1 .. . .
- j. y 2,1 PPM To'iucnc 0 19 PPM Benzene
before LV spectrum. i 1
j •.OPPM OXylene , . j
i'BO 760 740 720 700 680
cm-i
660
Figure 2, PAPA Technique for Aromatic Hydrocarbons. 45 Meter Cell.
580
-------
Advantages and Applications
Advantages of the PAPA measurement technique include:
(1) PAPA can be quick. Only a few minutes time is required to produce the results of
the analysis.
(2) It is simple. No chemicals are needed in the analysis. N'o measurements of flow or
pressure are required. No calibrations are called for. The calibration is inherent in the use of
the digitized reference spectra.
(3) It is sensitive. With just a modest-sized PAPA cell, detection limits for most
compounds are on the order of a few pans-per-billion.
(4) PAPA does things that no oilier analytical method can do, such as convert compounds
to more easily measured forms.
(5) A PAPA system can be used in its special applications, and then without modification
it can be used in regular infrared applications.
Here are some of the special applications envisioned for the PAPA system.
(1) Measure nitrogen oxides and other nitrogen-containing pollutants in air and in
combustion effluents.
(2) Measure organic pollutant gases in air and in combustion effluents.
(3) Measure isoprene, pinenes and other reactive natural hydrocarbons in air.
(4) Measure hydrocarbons and other impurities in ground water.
(5) Measure hydrocarbons and other impurities in soil samples.
(6) Measure sulfur-containing pollutants in air. combustion effluents, soil, and water.
(7) Measure impurities in carbon dioxide, including sulfur containing pollutants.
Future Work
The potential of the PAPA method has not yet been fully explored. Topics for further
study include the following.
581
-------
(1) T'ae benefits of working at pressures lower than one atmosphere.
(2) The relationships between spectral resolution and detection limits.
(3) Gains from working at longer optical paths.
(4) The possibilities of measuring homonuclear diatomic molecules by observing their
reaction products, such as o?one from oxygen, hydrogen chloride from molecular chlorine and
hvdrogen fluoride from molecular fluorine.
(5) Improving the data processing programs for the spectra so that the subtractions and
quantitative analyses may proceed with only minimal operator interaction.
RfcFERfcNCfcS
(1) Gas Measurement in the Fundamental ljifered_Region, by Philip L. Hanst and Steven T.
Hanst. pages 335 through 469 in Air Monitoring by Spectroscopic Techniques. M. W. Sigrist.
liditor: John Wiley and Sons. Inc.. 1994.
Finlayson Pitts and James N. Pitts. Jr., John Wiley and Sons, Inc.. 1986. 1098 pp.
-------
FTIR Transmission Spectroscopy for Quantitation of Ammonium
Bisulfate in Fine Particulate Matter Collected on Teflon Filters
Kenneth H. Krost and William A. McClenny
Atmospheric Research and Exposure Assessment Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
ABSTRACT
A quantitative measurement method for fine particle bisulfate
in ammonium bisulfate collected from the ambient air onto Teflon
filters is described. Infrared absorbance measurements of the
Teflon filters are made before and after particle collection.
Subtraction of the two spectra reveals the absorbance spectrum for
the particulate. The presence of bisulfate is identified by
characteristic and unique spectral features including prominent
absorption bands at 1050 cm-1 and 870 cm"1. The area seen under of
the absorption band centered at 870 cm-1 is calibrated for the
bisulfate ion by measuring the hydrogen ion concentration for a
series of ammonium bisulfate calibration standards. Ar, indirect
measurement of the bisulfate ion is made by inference from
measurement of the sulfate ion concentration as determined by ion
chromatography. The lower limit of detection (LLD) for the
bisulfate ion is 150 nanomoles. This corresponds to the total
ammonium bisulfate which would be collected from an air volume
containing 1.2 micrograms/m3 sampled for 24 hours at 10.0 L/min.
This method provides a specific, nondestructive, direct measurement
of ammonium bisulfate. As such, the method has distinct advantages
over indirect methods involving ion balance in solution.
-------
INTRODUCTION
A lurge percentage of sulfate in the ambient air exists in the
fine (< 2.5 microns) particle fraction, originating froir. the gas
phase through chemical reactions in the atmosphere. Fine particles
can be separated from coarse particles using size fractionating,
particulate sampling devices such as dichotomous samplers1, or in-
line filter packs with size fractionating inlets2. For these
samplers, particles are collected using Teflon filters over
sampling intervals of several hours to one week. Filters are
generally subjected to nondestructive elemental analysis by X-ray
fluorescence3 followed by water extraction and analysis by ion
chromatography4 and/or ion selective electrode for cations and
anions.
The potential usefulness of FTIR transmission spectroscopy for
the identification of ammonium, sulfate, bisulfate and other ions
has been noted in the literature5-10. Special studies with a limited
number of samples have shown the utility of the method5'10 for
sulfate measurement in ammonium sulfate. These studies used
samples from an archived filter bank. For such samples no attempt
was made to preserve the acid sulfate and hence the sulfur present
was in the form of neutral ammonium sulfate.
RESULTS
A typical spectrum of ammonium bisulfate collected on to a
Teflon filter is shown in Figure 1. Bisulfate bands occur at 870
cm-1, 1050 cm"1 and 1215 cm-1. The 870 cm-l band is in a region that
contains no significant Teflon absorption bands and is free from
other over lapping spectral bands seen in typical environmental
samples. The integrated area centered at 870 cm"1 ± 36 cm"1 is
thus used for quantitative purposes. The area is measured and
compared to a calibration curve to obtain the amount of bisulfate
present in the sample. To obtain the most accurate measurement of
absorbance, the filters are indexed with respect to their position
in the filter holder. This practice lowers the detection limit10
and tends to eliminate the effect of asymmetric scattering from the
uneven stretch patterns in the Teflon filter.
CALIBRATION
A calibration response for the system was obtained by
measuring the absorbance of standards prepared with a TSI Model
37 06 aerosol generator and sampled from a manifold using an in-line
Tefion filter pack. Standard filters were loaded with ammonium
bisulfate ranging from 85 ugm to 350 ugm each. The absorbance
spectrum was taken from 4000 to 400 cm"1 and the area centered at
870 cm"1 ± 36 cm"1 was integrated for the bisulfate measurement.
The filters were then extracted with 20 ml of water using
ultrasonification for 60 minutes. A 0.5 ml aliquot of the sample
58-1
-------
was then analyzed using an Orion Model 511 ion selective electrode
for direct determination of hydrogen ion. Measurements of sulfate
were also made on a Dionex Model 4000 ion chromatography Since the
measurement of sulfate was considered very reliable, sulfate was
used as a surrogate for hydrogen ion. Based on the respective
slopes, the calibration curve generated from the direct
determination of hydrogen ions is on average 10.6% lower than the
hydrogen ion calibration curve generated from equivalent sulfate
ion values. This difference may be due to the difficulty in making
low level hydrogen ion determinations using the ion selective
electrode. Another possible explanation could be the
neutralization losses that occur with acidic samples due to the
presence of ambient ammonia. The FT-IR analysis LLD computed for
a 3/1 signal to noise ratio was 150 nanomoles of bisulfate ion.
This computation was made by computing the FT-IR integrated area
for a known calibrated standard. The LLD was then computed for a
theoretical area having a 3/1 signal to noise ratio, based on the
aforementioned standard. This method of determining the LLD was
necessary because of the inability to accurately determine hydrogen
ion concentrations using traditional wet chemical means at
extremely low levels. The LLD stated corresponds to a collected
sample weight of 17.3 ug of ammonium bisulfate on a standard 37mm
teflon filter.
CONCLUSION
The applicability of FT-IR transmission spectrometry to the
quantitative and qualitative determination of ammonium bisulfate
has been demonstrated. The method is nondestructive and provides
a direct measure of ammonium bisulfate. Qualitative indicators for
the presence of ammonium bisulfate are absorption bands at 870 cm-1
and 105)0 cm-1. These bands along with the spectral shift that
occurs for the neutral sulfate band normally seen at 620 cm'1
confirm the presence of ammonium bisulfate. The integrated area of
the 870 cm-1 absorption band when calibrated against standard wet
chemical techniques can be used to determine the concentration of
bisulfate ion present in ambient aerosol. The lower detection
limit cited at this stage of development is 17.3 ug (150 nnoles) of
sample collected as ammonium bisulfate on a 37 mm Teflon filter.
The limiting calibration factor in the method is the uncertainty
that exists with the wet chemical determinations. The slope of the
calibration curve for bisulfate determination is 10.4% lower using
direct hydrogen ion measurements as compared to the use of sulfate
ion as a surrogate for hydrogen ion. As with other methods used to
analyze particulate matter collected on filters, the sample
integrity cannot be assured because of interaction among particles.
However, this is minimized by removal of the coarse particles and
by protection of the bisulfate from neutralization by basic gases
such as ammonia.
585
-------
REFERENCES
1. Dzubay, T.G. and Stevens, R. K. (1975) Ambient Air Analysis
with Dichotomous Sampler and X-ray Fluorescence Spectrometer.
Envir. Sci. Technol. 9, 663-668.
2. Goulding, F.S. and JaXlevic, J.M., X-ray Fluorescence
Spectrometer for Airborne Particulate Monitoring," EPA Report No.
EPA-Ra-73-182, April 1973.
3. Vossler, T.L., et.al., (1988) Evaluation of Improved Inlets
and Annular Denuder Systems to Measure Inorganic Air Pollutants,"
Atmospheric Environment, Vol. 22, No. 8, pp 1729-1736.
4. Mulik, J.D., Puchett, R., Williams, D., Sawicki, E., (1976) Ion
Chromatographic Analysis of Sulfate and Nitrate in Ambient
Aerosols, Analyt. Lett. 9, 653-663.
5. McClenny, W.A., Childers, J.W., Rohl, R., Palmer, R.A., (1985)
FTIR Transmission Spectrometry for the Nondestructive Determination
of Ammonium and sulfate in Ambient Aerosols Collected on Teflon
Filters, Atmospheric Environment, 19, 1891-1898.
6. Cunningham P.T. and Johnson, S.A. (1976), Spectroscopic
Observation of Acid Sulfate in Atmospheric Particulate Samples.
Science, 191, 77-79.
7. Johnson, S.A., Kumar, R. and Cunningham, P.T. (1983) Airborne
Detection of Acidic Sulfate Aerosol using ATR Impactor, Aerosol
Science and Technology, 2: 401-405, 1983.
8. Cummingham, P.T., Holt, B.D., Johnson, S.A., Drapcho, D.L., and
Kumar, R. , Acidic Aerosols: Oxygen-18 Studies of Formation and
Infrared Studies of Occurrence and Neutralization," Chapter 2
in Chemistry of Particles, Fogs and Rain, Jack L. Durham,
Editor, Acid Precipitation Series - Volume 2, John I. Teasley,
Series Editor, Butterworth Publishers, Woburn, MA, 1584, pp. 53-
129.
9. Gendreau, R.M., Jakobsen, R.J., Henry, W.M., Knapp, K.T. (1980)
Fourier Transform Infrared Spectroscopy for Inorganic Compound
Speciation, Environ. Sci. and Tech., 14, 8, 990-995.
10. Krost, K.J. and McClenny, W.A. (1992) Fourier Transform
Infrared Spectrometric Analysis for Particle-Associated Ammonium
Sulfate, Appl Spectrocopy, 46, No. 11, 1992, 1737-1740.
586
-------
0.1200
0.1000
0.0800
r>
3 M
CO
? a
€ 0.0600
NH,
m HSO,"
** A
TJ W II
so,
0.0200
0.0000
1600.0 1450.0 1130.0 1150.0 1000.0 850.0 700.0 550.0 400.0
Wavenumber, cm-'
Figure 1. Absorbance Spectrum
of Ammonium Bisulfate Standard
-------
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
FOURIER TRANSFORM INFRARED SPECTROSCOPY
TEST PROGRAM FOR EMISSIONS MEASUREMENT
Lori T. Lay
Emissions Measurement Branch
Technical Support Division
Office of Air Quality Planning and Standards
ABSTRACT
The U.S. Environmental Protection Agency (EPA) published
amendments to the Clean Air Act (CAA) November 15, 1990. Title
III of the CAA amendments included a list of 189 hazardous air
pollutants (HAP's) for which emission test procedures must be
established.
An extractive emission test method, using Fourier Transform
Infrared (FTIR) spectroscopy, is being developed for measuring
HAP compounds. The FTIR procedure has the potential to detect
over 100 of the listed compounds plus additional compounds such
as criteria pollutants. This procedure has the ability to detect
multiple compounds simultaneously and will provide near real-time
data.
Since the development of the extractive FTIR procedure, many
source categories have been screened for HAP emissions using this
technique. Modifications to the procedure have been made and
validation testing has been performed. Currently, this technique
is being used to collect data for maximum achievable control
technology (MACT) standard development.
INTRODUCTION
This paper focuses on the application of FTIR to emissions
testing of various air pollution sources. This involves
extracting samples from stacks or ducts in industrial sources.
(See figure l.j The development of the testing program has
involved several phases. The first phase involved the
development of sufficient reference spectra, software, and an
FTIR Protocol1 to guide in making these measurements. The second
phase involved the development of sufficient sampling systems and
performing screening tests at several source categories to
evaluate the protocol and potential sampling systems. The third
phase involved the validation of this technique for 46 HAP's at a
588
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coal-firod boiler. Currently, the extractive FTIR technique is
being used to collect emission data in support of MACT standards.
EXTRACTIVE FTIR DEVELOPMENT AND TESTING PROGRAiM
Phase 1
Duo to the lack of sufficient reference spectra for the
HAP's, the Emission Measurement Branch sponsored Entropy
Environmentalists, Inc., to develop reference spectra for over
100 HAP's. These spectra are available through the emission
measurement technical information center (EMTIO) bulletin board
system2. The FTIR Protocol, noted previously, servos as a
guideline for the use of extractive FTIR systems in emission
testing. It provides a basis for the source-specific integration
of sampling procedures, reference spectra and software
development, and quality assurance/quality control procedures.
The protocol specifies extractive sampling guidelines and
calibration transfer techniques. The protocol is currently
designed for users with extensive FTIR training, but a practical
FTIR tost method must be suitable for performance by an operator
with less experience. The transition between the protocol and a
test method will require that suitable reference spectra and
user-friendly software be made generally available.
Phase 2
After the development of appropriate reference spectra,
software, sample conditioning systems were developed. Sample
conditioning systems are necessary to deliver the stack gas to
the FTIR sample cell in a condition that will not damage the FTIR
cell and optics and will reduce spectra] interference. This
involves filtering particulate, and, in certain cases, removing
moisture. These sample conditioning systems were (1) the hot/wet
system, (2) the perma-pure system, (3) the condenser system, and
(4) the preconcentration system. The first three systems listed
are considered direct sampling systems. The hot/wet system draws
the sample through a heated filter and heated teflon line. The
perma-pure and condenser system remove moisture. The
preconcentration system involves sample collection in a sampling
train (Method 0010 ) which uses tenax as an absorbent. The tenax
is thermally desorbed into the FTIR sample cell for analysis.
After the development of these systems, screening tests were
performed to gain preliminary "qualitative" emission data on
potential HAP's from these sources and to evaluate the FTIR
procedure (sample conditioning systems and analysis). Source
categories, where screening testing was conducted, included pulp
and paper, portland cement, wool fiberglass, primary aluminum,
secondary aluminum, secondary lead, ana utility boilers. Certain
source categories were of particular interest because of the
upcoming MACT standard development. Based on these screening
5X9
-------
tests, modifications to the sample conditioning systems were
made, based on target compounds and expected concentration levels
of these compounds at these sources.
Results of phase 1 and phase 2 were presented in more detail
at the Air and Waste Management Association annual meeting in
June of 1992.'•
Phase 3
In January and February of 1993, validation testing was
performed at a coal-fired boiler following Method 301
procedures5. The validation testing involved dynamically spiking
46 HAP compounds. Dynamic spiking involves spiking the sample
gas at the sample probe (immediately prior to the filter) and was
conducted using known concentrations of the target compounds.
The compounds chosen were those that were available as cylinder
gases to be used as the standards. Three of the sample
conditioning systems were tested: the hot/wet system, the
condenser systems, and the preconcentration system. Of the
systems which were tested, the hot/wet and condenser sampling
systems, together, validated for 32 of the 46 compounds. The
preconcentration system validated for 11 of the compounds. Data
for a number of other compounds did not meet the Method 301
criteria; however, they demonstrated more than adequate
performance of the FTIR technique for use as a screening
procedure.
Utility study and MACT standard development.
The FTIR procedure has been used to gather information for
the utility report to Congress and to gather information for MACT
standard development. In all cases, both controlled and
uncontrolled emissions from the various processes were of
interest. The preconcentration system was developed because of
the low levels (low part-per-biHi on) of HAP's from utility
boilers. Five utility boilers were tested: two coal-fired
boilers, two gas fired boilers, and an oil-fired boiler.
Two portland cement facilities were tested using FTIR to
gather data to set a MACT standard. The target compounds for
this source cateqory were acetaldehyde, benzene,
bis(2-ethylhexyl)phthalate, carbon disulfide, chloromethane,
formaldehyde, hydrochloric acid, naphthalene, phenol, styrene,
toluene, and xylenes. The HAP's that were detected at the first
plant were benzene, carbonyl sulfide, formaldehyde, hydrochloric
acid, and naphthalene. All compounds were detected with the
preconcentration train at hiqh ppb levels, except KC1, which was
detected with one of the gas phase systems (parts-per-million
level detection limit). Emissions were evaluated at the inlet to
a carbon injection sysren and baghouse (in series) and the outlet
of the baghouse. The HAP's, detected at the second facility,
590
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were benzene, chlorobenzene, hexane, naphthalene, styrene,
toluene, and o-xylene. All compounds were detected with the
prcconcentration train, except hexane and xylenes which were
detected in the gas phase system. The emissions were sampled
from a rotary kiln both before and after a ir.ulticlone and
baghouse (in series), and before and after a scrubber. Other
compounds, detected at both facilities which are not HAP's,
included sulfur dioxide, nitric oxide, methane, and ethylene.
Emissions from two mineral wool fiberglass facilities were
also evaluated for MACT standard development using the extractive
FTIR procedure. Target compounds for the FTIR were phenol,
formaldehyde, and methanol. The test reports for these
facilities have not been completed. However, preliminary results
indicate that phenol, formaldehyde, methanol and carbonyl sulfide
were detected at both facilities. For the first test, the
emissions from a bonded line were sampled at the inlet and outlet
of a baghouse, which controlled the cupola emissions. The inlet
and outlet emissions of a filter house, which controlled the
collection drum, were evaluated. The inlet and outlet of an
incinerator, which controlled the curing process emissions, and
the uncontrolled emissions from the cooling process were also
evaluated.
For the second test, both emissions from a bonded line and a
nonbonded line were sampled. Emissions from the incinerator and
baghouse, controlling the cupola emissions, were also sampled.
For the bonded line, the emissions from a filter house,
controlling the collection drum emissions, were evaluated.
Emissions from an afterburner, controlling the curing process
emissions, were evaluated, and emissions from a common stack for
the baghouse and filter house, mentioned above, were evaluated.
For the nonbonded line, the emissions from a filter house,
controlling the collection drum emissions, were evaluated.
CONCLUSIONS
The FTIR procedure has provided extremely promising results.
This technique has been validated for many of the HAP compounds
at a coal-fired boiler and is currently being used to collect
data in support of MACT standards. Future plans for FTIR testing
include a wool fiberglass facility and a secondary aluminum
facility.
REFERENCES
1. Lay, L.T., Plummer, G.M., Protocol for Applying Fourier
Transform Infrared (FTIR) Spectrometry in Emission Testing -
Draft Version S7. November 12. 1992.
59!
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2. EMTIO Bulletin Board System of the EPA Office of Air Quality
Planning and Standards Technology Transfer Network, to access
(919) 541-5742, EMTIO Help Line (919) 941-5222.
3. U.S. Environmental Protection Agency. Test Methods for
Evaluating Solid Waste: Physical/Chemical Methods. EPA
Report No. SW-84 6, U.S. Environmental Protection Agency,
Washington, DC, 1982.
4. Lay, L.T., Pluramer, G.M.. "US EPA Application of FTIR for
Determination of Title Til Air Toxics Emissions." in
Proceeding of the 1992 A&WMA 85th Annual meeting and
Exhibition, 92-99.09; Air and Waste Management Association:
Kansas City, 1992.
5. Lay, L.T. , Plujniner, G.M. , et al. ; Fourier Transform Infrared
fFTIR) Method Validation at a Coal Fired Boiler.
EPA-68D20163; U.S. Environmental Protection Agency: Research
Triangle Park, 1993.
592
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interferometer
sample cell
detector
computer
JO^X'xx
V/xxVV
V;:yy>
sample
conditioning
system
Figure 1. FTIR Extractive Sampling Schematic
-------
Intentionally Blank Page
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SESSION 12:
NEW METHODS FOR VOCS
-------
Intentionally Blank Page
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The Concentration and Measurement of Air Pollutants by GC'/MS;
A Comparison of Sorbcnt Versus Cryo Trapping
Llizabeih Almasi and Norman Kirshen
Varian Chromatography Systems
2700 Mitchell Drive
Walnut Creek. CA 94598
Tlie measureuem of to.xic air contaminants and ozone precursors in ambient air
is gaining more importance as the 1990 Clean Air Act Amendments (CM) take effect.
Simple, reliable and low maintenance instrumentation is needed to detect the more
than 100 volatile organic compounds (VOCs) in ambient air at low or sub pph levels
as specified in the CAA.
A Saturn GC7MS ion trap system equipped with an inboard concentrator (SPT)
was used to study the advantages and disadvantages of cryo and sorbcnt trapping of
the pollutants. The cryo trapping was carried out on glass beads at -150C or -180C,
using liquid nitrogen as coolant. The sorbcnt trapping look place at or around ambient
temperatures employing custom selected sorbcnt traps and liquid C02 for cooling.
Sample volumes of 60ml and higher were concentrated, and after separation on a
capillary column, full scan detection was petformed.
System precision, detection levels and linearity data will be presented for
different compound groups and results of ambient air samples will be shown.
597
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A Real Time Sorbent Based Air Monitoring System
For Determining Low Level Airborne Exposure Levels to Lewisite
Fnuik G Lattin, Chief, Monitoring Branch
U.S. Army Edgewood Research, Development and Engineering Center.
Operations Directorate, Chemical Support Division,
Aberdeen Proving Ground, MD 21010
Donald G. Paul, Director of Research and Development,
Dynatherm Analytical Instruments, Inc., P. O. Box 159, Kelton. PA 19346
Edward M Jakubowslti, Ph.D., Laboratory Director
SciTech Services, Inc., 1311 Continental Drive, Suite G, Abingdon, MD 21009
ABSTRACT
The Real Time Analytical Platform (R'I'AP) is designed to provide mobile, real-time
monitoring support to ensure protection of worker safety in areas where military unique
compounds are used and stored, and at disposal sites. Quantitative analysis of low-level
vapor concentrations in air is accomplished through sorbent-based collection with subsequent
thermal desorption into a gas chromatograph (GC) equipped with a variety of detectors. The
monitoring system is characterized by its sensitivity (ability to measure at low
concentrations), selectivity (ability to filter out interferences), dynamic range and linearity,
real time mode (versus methods requiring extensive sample preparation procedures), and
ability to interface with complimentary GC detectors.
This presentation describes an RTAP analytical method for analyzing Lewisite, an
arsenical compound, that consists of a GC screening technique with an Electron Capture
Detector (ECD), and a confirmation technique using an Atomic Emission Detector (AED).
Included in the presentation is a description of quality assurance objectives in the monitoring
system, and an assessment of method accuracy, precision and detection levels.
INTRODUCTION
Lewisite (2-chlorovinyldichloroarsine) is a toxic arsenical compound of historical
military interest (Table 1). Since Lewisite is a suspected carcinogen, it is necessary to
monitor vapor concentrations to protect worker safety in areas where the chemical is stored
or that contain items that may have been exposed to the chemical, and in former
manufacturing areas during installation restoration activities.
Historical Methodology
Because of the need for accurate assessments of exposure levels, a number of analytical
methods for the detection of Lewisite have been developed. The thermal instability of the
compound and its reactivity with water have complicated the search for quantitative
measurement techniques and are reported extensively in the literature'. Since attempts to
analyze Lewisite directly via gas chromatography result in severe deterioration of the
chromatographic column and metal surfaces of the detector, most accepted methods rely on
598
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indirect measurements of either elemental arsenic or a reaction product. One conventional
measurement analyzes trace arsenic by graphite furnace atomic adsorption2, another quantifies
trace levels of acetylene formed during the alkaline decomposition of the chemical3. A
current approach uses high pressure liquid chromatography with UV and electrochemical dual
detection to analyze hydrolyzed Lewisite (2-chJorovinylarsonous acid, CVAA)'.
limitations
Each of these traditional approaches can be limited by the presence of interfering
substances, i.e. naturally occurring arsenic collected and reported as Lewisite. Similarly,
Lewisite derived acetylene is indistinguishable from acetylene that enters the sample stream
as a background constituent. It has been reported that headspace samples of acetylene
generated from Lewisite typically contain water vapor artifacts, a 9:1 ratio of water vapor to
acetylene, that reduce the sensitivity of the analytical detector, limiting detection levels5.
Also, all of these methodologies involve collection of samples by passing air through a
liquid filled iinpinger (bubbler) or filter media, which is labor intensive and costly, can
impose a delay of several hours to several days before analytical results are obtained, and
requires expensive decontamination and disposal procedures of waste water and solvent.
In search of more accurate, reliable and cost effective methodology, the Edgewood
Research, Development and Engineering Center (ERDEC) at Aberdeen Proving Ground, MD,
and other research organizations at APG have funded various studies investigating other
Lewisite reactants, specifically with thiols. Jakubowski6 et.al. and Albro7, continuing with
derivatization tecliniques suggested by Peters8 and reported by Fowler9 developed GC
methods for analyzing the derivative of Lewisite and hydrolyzed Lewisite after derivatization
with 1,2 ethanedithiol (EDT). They described the use of more sensitive and selective GC
detectors, the flame photometric detector (FPD) and electron ionization mass spectroscopy
(EIMS), and introduced elemental analysis with the Atomic Emission Detector (AED) to
further extend the lower concentration range at which quantitative measurements of Lewisite
could be obtained. Most of this body of work concentrated on measurements of the purity of
Lewisite standards in solvents, and detection of Lewisite in water and soil samples. EDT
derivatization as a means of measuring vapor concentrations in air were basically obtained by
analyzing water from samples collected through bubblers.
Technical Approach
This method's approach utilizes sorbent tube technology for the monitoring of airborne
Lewisite. The solid sorbent Tenax is substituted for bubblers, with subsequent thermal
desorption into a GC column. Sensitivity increases, since all of the collected sample is
available for analysis, instead of an aliquot of the extracted bubbler medium. After
desorption, sorbent cartridges are reusable, with no costs incurred in the disposal of waste
water or solvents.
Due to Lewisite's thermal instability, derivatization was seen as an excellent means of
producing a stable compound analyzable by GC. The derivatizing agent, most likely reacting
with hydrolyzed Lewisite due to the moisture in the air, converts it to a compound that
retains its Arsenic molecule, in combination with other molecules that allow both an AED
and Electron Capture Detector (LCD) to respond to the reaction product with sufficient
sensitivity without interference from the derivatizing agent (Figure I). 1,4 thioxane was
substituted for 1,2 ethanedithiol because of problems with EDT purity that limited detector
599
-------
response on the FPD and Electron Capture Detector (ECD). Derivatization was
accomplished by injecting the derivatizing agent directly on the tube containing the airborne
adsorbed Lewisite hydrolyzate.
A Dynatherin ACEM 900 thermal desorber, coupled with a Hewlett Packard 5890 GC
with an LCD serves as a prescreemng system during analysis of the sampling tube. It saves
approximately 75% of the sample so that subsequent analysis of the same sample can be
made on the confirming system, consisting of an ACEM 900 and IIP 5890 GC with an
Atomic Emission Detector. The ACEM has an integral sample saver that splits the sample
during thermal desorption between the column on the prescreening GC and a second sorbent
tube. If the screening GC generates a positive response, the saved portion of the sample on
the auxiliary sorbent tube is available for analysis on the confirmation GC. Both the ECD
and AED give quantitative as well as qualitative results. [The Dynathcrrn / HP-GC / HP-
AED system has been previously reported in the literature1"].
EXPERIMENTAL
Precision and accuracy studies (P&As) performed to validate the method specified a
minimum range of .25 - 1.5 times the Time Weighted Average (TWA), currently set at .003
mg/nV (.35 ppb), and required 5-point calibrations, in duplicate, over a four day period. A
CASARM Lewisite standard was diluted to a concentration of 1.08 ng/ul in methanol. The
derivatizing agent, 1,4 thioxane, was made up in a 1.2% solution in methanol. Standards may
be introduced to the sorbent collection tube either as a liquid or gaseous injection. A liquid
Lewisite standard was used for the P&As because it appeared to have better stability over
longer periods of time. Table 2 lists the injection amounts relative to the percentage of TWA,
with 1 TWA based on a 1.6 liter air sample.
After the standard was injected through a special injection port adapted for the
Dynatherm Six -Tube Conditioner, Model 60, the sorbent tube was purged with nitrogen at
600 cc/minute for 3 minutes. This was followed by injection of the derivatizing solution,
purged at the same rate for twice the time. A sleeve heater slipped over the tube during the
derivatizing process maintained an elevated temperature of 70°C to ensure consistency of
reaction and remove residual water and solvent. After loading with the derivatized standard,
the tube was transferred to the ACEM 900 for thermal desorption into the GC/ECD system.
The ECD and AED systems were calibrated with the same sample, split via the ACEM
sample saver, and the curves from both detectors plotted. It was necessary to verify that
neither detector was adversely affected by the splitter or concentration changes. Each
detector gave a linear response within the required range, with correlation coefficiencies
ranging from .996 - .999 (Figures 2 and 3).
Column information and temperature, time and flow conditions for the ACEM 900, GC
oven and detectors are presented in the parameters log ( I'able 3).
The only interferences predictable from the P&As are those compounds associated with
the Lewisite standard and derivatizing agent, reflecting less than 100% purity levels of both
chemicals 1'hough background compounds appear in the chromatograms of both the LCD
and AED systems, none appear at or near the same retention time of the peak of interest.
Since the ECD does not have the elemental selectivity of the AED, interferences introduced
during actual field sampling are possible. Should an interference appear within the LCD
retention time window, it will be subject to investigation on the AED system. Only a
compound producing an arsenic response within the AED retention time window will be
600
-------
confirmed as positive. The likelihood of such an interference is remote.
The turnaround time with either the ECD or AED system is approximately 15 minutes, an
analysis rate of 4 per hour. Only positives generated on the ECD system require analysis on
the AED system.
Detection limits on both systems are well within current exposure limits. Under the
conditions described for the P&As, the lowest concentration analyzed by the ECD system was
less than .25 ng on column. Area counts were in excess of 150000, with a high signal to
noise ratio. Sensitivity of the AED when monitoring at 189 nm for arsenic was also very
high. Note also that sample volumes are based on a response to 1.6 liters of air at 1 TWA.
Given the structure of the derivatized compound and the surface area of the Tenax adsorbent,
one could predict good collection efficiency at 4 to 6 times current sampling volumes. Based
on these factors, there is a liigh probability that exposure levels could be monitored al
significantly lower vapor concentrations than current TWA. Determination of the minimum
detection level of this method would require study of absolute detector sensitivity for the
ECD and AED, establishment of breakthrough volume on the adsorbent tube, and the effect
of higher concentrations and sampling volumes on derivatizalion efficiency.
CONCLUSIONS
The method as described for the analysis of Lewisite and/or its hydrolyzed product
through solid sorbent collection of airborne vapors, derivatization to a chromatographable
compound, and analysis by two specific GC detectors offers high sensitivity and selectivity.
The risk of false positives due to environmental interferences should be low. Detection
levels are such that measurement of exposure values below current TWA can be investigated.
Significant cost savings through elimination of waste products can be obtained.
Field tests of the method to date have been promising, though no positive response other
than to spiked samples has been recorded. Operator skill levels, while requiring some
familiarization with gas chromatography and analytical capability, are not excessively high.
Future research suggested by the success of the current approach will be devoted to
adaptation of the method to real time continuous monitoring. The same analytical equipment
described in this method could also collect and analyze air samples unattended with the
addition of a fixed amount of derivatizing agent in gas form. The basic format and
instrumentation of the Army RTAP mobile laboratory, already fielded at a number of storage
depots and in use by Monitoring Branch for worker exposure assessments, could be modified
with the appropriate equipment for lewisite analysis The dual methodologies, for sampling
with easily portable sorbent tubes and unattended monitoring with a real-time monitor, would
present an ideal solution to the various difficulties encountered in F.ewisite vapor exposure
assessments to date
601
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REFERENCES
1. Waters, W.A and Williams, J.H.. Ilydrolyses and Derivatives of Some Vesicant
Arsenicals, J. Chem Soc., 18 (1950)
2. Joiner, R.L.; Hayes, T.L.; Arp, J.C.; Twit, F.R., Validation of an Analytical System for
the Determination of Lewisite (L) in Environmental Air and Proof of Decontamination
Samples. DAMD17-83-C-3129, U. S Army Medical Research and Development Command
Institute of Chemical Defense, October 1989. UNCLASSIFIED REPORT.
3. Valis, R.J ; Kolakowski, J.E., Development and Application of a Gas Chromatographic
Method /or Determination of Lewisite Emissions During Incineration of Obsolete Chemical
Agent Identification Sets, ARCSL-TR-81092, U.S.Army Chemical Systems Laboratory,
Aberdeen Proving Ground, Ml), December 1981, UNCLASSHTliD REPORT.
4. lillzy, M.W.; Bossle. P.C.; Rosso, T 11, Lewisite Collection: Feasibility Study, 2WLM3,
U.S. Army Chemical Research, Development and Engineering Center, Aberdeen Proving
Gr ound, MD. December 1992.
5. Ellzy, M.W.; Janes, L.G.; Plcva, S.G.; Piffath, P.C.; Bossle, P.C.; Rosso,T.R, Verification
of a Gas Chromatographic Method of Determination of Lewisite Time-Weighted-Average
Concentration in the Environment as Used by the Soviet Union, Manuscript TR, U.S. Army
Chemical Research, Development and Engineering Center, Aberdeen Proving Ground, MD,
September 1991. UNCLASSIFIED REPORT.
6. Jakubowski, E.M.; Logan. T.P.; Smith, J R.; Dolzine, T.W., Quantitation of Lewisite
Prepared in Organic Solutions Using Gas chromatography, 1-23-85-000-A371, Analytical
Chemistry Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen
Proving Ground, Ml), July 1992, UNCLASSIFIED REPORT
7. Albro. T.G.. Determination of Lewisite (L) and It's Ilydmlysis Product in Soil and Water
by Gas Chromatography with Atomic Emission Detection (AED), presented at the 1994
Pittsburgh Conference, Chicago, II., March 1. 1994.
8. Peters, R.A.; Stocken, L.A.; Thompson, R.H.S., Nature 156, 616 (1945).
9. Fowler. W.K.; Stewart, D.C.; Weinberg, D.S.; Sarver, E.W..J. Chromatogr. 558, 235
(1991).
10. Oliver. K.D.; Daughtry, E.H.; McClenny, W.A., "Evaluation of a Sorbent-Based
Preconcentrator for Analysis of VOCs in Air Using Gas Chromatography - Atomic Emission
Detection", in Proceedings of the. 1992 Ll.S.EPA/A&WMA International Symposium on
Measurement of Toxic and Related Air Pollutants, V1P-25. Air and Waste Management
Association: Pittsburgh, 1992; pp 395-400.
602
-------
4
Figure 1. Products fcnned when hydrolyzed Lewisite, CVAA, is derivitized with 1,4 Tliioxane
6(T>
-------
Figure 2. Linearity During 4-Day P&A Study
ECD Detector
Day 1
Regression Statistics
Aiua= 89205(Amt) + 68232
r= 0.996608073
DmJ.
Regression Statistics
Area- 87871(Amt) • 131573
0.996611364
Day 3
Regression Statistics
Area 103163(Aint) + 168951
r= 0 999695326
Day 4
Agression Statistics
Arca= 109476(Amt> . 209927
r*= 0 999021548
TARGET CVNCZff°A~'r3 H HAtKKKtMS
ARGE T COKCfrWT^ATiOff NANCCiRAM
TARGET CC#C4:HTKAnOH NANGGRAMS
e '
TAMGST CCNCSHTKATK3M NANOGRAMS
604
-------
Figure 3. Linearity During 4-Day P&A Study
AED Detector
Day 1
Regression Statistics
Area" )250.85(Amt) + 652,28
l*= 0.998851517
firrrj
Eta2
Repression Statistics
Area 1280 40(Amt) + 795 82
f- 0.99764992
r»iwrcaficg*r*Am* Ht/totiUMs
osa
Regression Statistics
Area- 1204.25(Aini) + 967,79
r= 0.999529939
."J
nvwerumzexmATTW*
Day 4
Regression Statistics
Area-- l273.45(Amt) l 86763
r 0999738575
605
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Lewisite: lMchIoro-(2-chlorovinyl)arsiiie
Molecular Formula: GRAsG,
Molecular Weight: 207.35
Boiling Point: 190°C
Vapor Pressure: 0.394mm Hg at 20°C
Table 1. Physical properties of Lewisite
Workplace Fxposure l^evel (TWA) 0003mg/nf = 0 35ppb
Fraction of TWA
20%
50%
100%
150%
200%
Amount Injected
in (i
1.0
2.3
4.6
7.0
9.3
in ng
im
2.4,S
4.97
156
10.04
Table 2. Injection amounts related to TWA
606
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1 aHc^ | AOF.M 900 / HP 5890IIGC System Parameters Log
'Method.
Lewisite Derivatization / DAAMS Tube / ECD Screen and AED Confirmation
^Operate: Lday Mehta
[ Date: 1/31/94
Flow Settings
Samplrg P'ow
'•nl'.r rule)
~
J
E
Vacuum
Pressufe
Online
Samcte Saver ECO 5>vstein on!v 0 ON
SpJi Kdtso b n^mm to focus trap Q O-F
15 mVmtn to sample saver
Sample lube
Purge/Desorb How
Nitrogen
20 mfmin
Focus Tube
Deserb/Celumn Fiow
Nitrogen J fcPC
4 rrf.'mn a Flow Certro'led
Surknt Tube Data
Tub*
Part Number
Materials
| CD j ID.
Samae CohfCt
Sample Saver
MX-'JMI41 ' 20:35
MX-7£-2ll7/20-36
Terwu-TA, 203b mesli, 11>0 mg J 6 mm S 4 mm
Tertax-TA. 20'35 mesh. 150 mg 6 mm | 4 mm
FocjS Ttif>
AC-06-W29
Tenax-TA, 20 3£> mesh / AWS fliass b»ads. 60 00 mesfc ¦ 6mm j 5mm
Temperature Setpoints
Va'vc
Tuoe Desorb
225 #C
350~"C
U OFF
~~ ~~5"orr
Transfer Line
"rap Des<^b
250 *C J OFF
350~*C~- 'jOrF
Tub*? ide
•c
PI OFF iTrap igl©
*C PI OFF
Time Setpoinls
Fk* Sample
0 m nute^s)
a OFF
Tube Coo!
2 mtnute(r.) U OrF
Tjbe Dty
4 nrrutefs)
_i OFT
Trap Heat
1 mrnute(s;
Tuoo Hrat
3 mmutc(s)
Sys. Recycle
0 minutc(s) ~ OFF
Other Controller Module Settings
GCD.fn Syr.tfjn
Romote Start
Bolh systems set 0«N
El ON
~ OFF
Cvcles Both systems set OFF El OFF
tr of Samples
Sarnplw Saver
Sp:it Faction
ECO system set CM
AfcD system set OFf-
a on
3 OFF
(X1 Column Data
Phase
ID.
Le/igth
Film Thickness
J«W DB-b
.53 mm
30 meters
1 b Mm
GCI ECD Conditions
Mtia' Temp.
80 *C
Firra- Temp.
275 'C
Initial HoW
1 minuW(s)
Finai Time
0 mtnuhj(s)
Rate 1 (A)
Rate 2 (0)
15 *C/rr^ut« to 1
-------
IDENTIFICATION OF AMBIENT AIR SAMPLING AND ANALYSIS
METHODS FOR THE 189 TITLE HI AIR TOXICS
R. Mukund, Thomas J. Kelly, Sydney M. Gordon, and Melinda J. Hays
Atmospheric Sciences and Applied Technology
BATTEL! ,E
505 King Avenue
Columbus. Ohio 43201 2693
ABSTRACT
The stale of development of ambient air measurement methods for the 189 Hazardous Air Pollutants
(HAPs) in Title III of the Clean Air Act Amendments was surveyed. Measurement methods for the HAPs
were identified by reviews of established methods, and by literature searches for pertinent research
techniques. Methods were segregated by their degree ot development into Applicable, Likely, and Potential
methods. This survey identified a total of 183 methods, applicable at varying degrees to ambient air
measurements of one or more HAPs. As a basis for classifying the HAPs and evaluating the applicability of
measurement methods, a survey of a variety of chemical and physical properties of the HAPs was also con-
ducted. The results of both the methods and properties surveys were tabulated for each of the 189 HAP.
The current state of development of ambient measurement methods for the 189 HAPs was then assessed from
the results of the survey, and recommendations for method development initiatives were developed.
INTRODUCTION
The 1990 Clean Air Act Amendments (CAAA) accelerated the pace of regulating toxic air pollutants
by establishing a list of 189 Hazardous Air Pollutants (HAPs). The HAPs are a remarkably diverse group of
compounds, including metals, pesticides, chlorinated and hydrocarbon solvents, industrial chemicals and inter-
mediates. combustion byproducts, complex chemical mixtures, and chemical groups such as polychlorinated
biphenyls. Some of the IlAPs are volatile organic compounds commonly measured as air pollutants. Many
other HAPs are widely recognized as toxic, but have previously only been addressed in workplace
environments. Some of the HAPs are not single compounds, but rather complex mixtures or groups of
chemicals spanning broad ranges of chemical and physical properties. A tew HAPs, such as titanium
tetrachloride, jhospliorus. and diazomethaiie, are unlikely to exist in ambient air because of their reactivity.
To meet the CAAA goals of defining and reducing human health risks from HAPs, ambient
measurements are needed. However, ambient measurement methods for the HAPs are generally lacking,
possibly because of a lack of adequate measurement methods and the diversity of the HAPs. A recent survey
of ambient HAPs data conducted for U.S. F.PA showed no ambient data for 74 of the 189 HAPs,1 and
furthermore found less than 100 ambient measurements for 116 of the HAPs.
The present study was conducted to identify existing and potential ambient measurement methods for
189 HAPs. This study differed from similar previous surveys2'5 in that the physical and chemical properties
of the H APs were compiled, and used as the basis for evaluating the applicability of measurement methods.
This survey also identified novel research methods, rather than relying solely on official compilations of
standard methods. Finally, this survey categorized the HAPs measurement methods by their state of develop
ment, distinguishing workplace, laboratory or stack emission methods from methods actually tested in ambient
air. The project final report4 provides complete details of the survey methods, results, assessment and
recommendations; this paper presents highlights of the study.
SURVEY METHODS
HAPs Properties
The chemical and physical properties of interest in this survey are those that affect the sampling and
measurement of HAPs in the atmosphere. To organize the compilation of properties, the HAPs were divided
into groups. As a starting point, the 189 HAPs were first divided into organic compounds and inorganic
compounds. This initial distinction was based largely on the designation of chemicals in the CRC Handbook
of Chemistry and Physics, and on the known nature of the HAPs The primary properties then obtained for
all the HAPs were vapor pressure (VP in mm of Hg at 25'C) and boiling point (and'or melting point)
temperature. The vapor pressure data were used to categorize and rank the HAPs. Quantitative vapor
pressure criteria were set up defining very volatile organic and inorganic compounds (VVOC. and VVIN'C:
608
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VP>380). volatile compounds (VOC and V1NC: VI" from 0.1 to 380), scmivolatile compounds (SVOC and
SVINC: VP from 10 ' to 0.1), and nonvolatile compounds (NVOC and NVINC: VP < IO"7 ). These vapor
pressure criteria are similar to those used in similar previous categorizations,5 except for the very volatile
categories. The vapor pressure criteria are somewhat arbitrary, and compounds with vapor pressures near the
criterion values generally fall into 'pray areas" that define gradual transitions from one volatility class to the
next. For the volatile and very volatile IIAPs, further chemical and physical properties were compiled,
consisting oi electronic polarizability, water solubility, aqueous reactivity, and estimated lifetime relative to
chemical reaction or deposition in the atmosphere.
The primary information sources used for the HAPs properties survey were handbooks and published
report1: of chemical and physical oroperties (references provided in the project report), including computer
data bases specifically addressing the 189 HAPs.5 Whenever possible, inconsistencies and errors were
corrected by comparisons of data from various sources, searches of the STN (Beilstcin file) computer data
base, and through consultations with F.PA staff7
HAPs Measurement Methods
The search for measurement methods for the HAPs was intended to be as wide-ranging as possible.
Information sources included standard compilations of air sampling methods, such as F.PA Source Test
Methods. HPA Contract Laboratory Program (Cl.P) and Compendium (i.e., TO- ) methods, as have been
used in previous surveys7-' However, this study also reviewed standard methods designated by the
Intersoeiety Committee on Methods of Air Sampling and Analysis, the National Institute of Occupational
Safety ar.d Health (NIOSH), the Occupational Safety and Health Administration (OSIIA), and the American
Society for Testing and Materials (ASTM). Additional sources of information were the two surveys recently
conducted by Battelle for F.PA on the ambient concentrations and atmospheric transformations1 of the HAPs.
The ambient concentrations survey was especially useful as a guide to measurement methods for HAPs, and
assured that methods were identified for all HAPs that have been measured in ambient air. In addition,
reports, journal articles, and meeting proceedings known to contain information on HAPs methods were
obtained and reviewer!. In general, highly complex and expensive spectroscopic research methods were
considered unsuitable for widespread monitoring and were not included in this survey.
The measurement methods identified for the 189 HAPs were organized into three categories,
depending on the degree of development of the method:
Applicable - An Applicable method was defined as one which has been reasonably established and/or
documented for measurement of the target HAP in ambient air: designation as an Applicable method docs not
necessarily imply that tiie method has been approval or certified by U.S. EPA for measurement of the target
HAP in ambient air. In most cases, methods identified as Applicable have actually been used for ambient
measurements. In other cases, a method was identified as Applicable for a specific HAP because of the
degree of documentation and standardization of the method, even though no ambient data were found. The
identification of a Applicable method does not guarantee adequate measurement of the pertinent HAP(s) under
all circumstances; simply, the method was evaluated to be capable of being applied to ambient air
measurements of the HAP. Further development and evaluation may be needed to assure sensitivity, freedom
from interferences, stability of samples, precision, accuracy, etc., under the range of conditions found in
ambient measurements.
Likely - Two types of Likely measurement methods were defined. The most common type is a
method which has been clearly established and used for the target HAP ill non ambient air, such as OSHA or
KIOSH methods established for HAPs in workplace air. The second type of Likely method consists of
lechniijjes identified as Applicable for one HAP, and consequently inferred as Likely for another HAP based
cn close similarity of chemical and physical properties.
Potential - A Potential method was defined as one which needs extensive further development before
application to ambient air measurements will be justified. Many Potential methods have been evaluated for
the target HAP in sample matrices other than air (e.g., water, soil). Potential methods were inferred for
some HAPs, based on Applicable or Likely methods found for other HAPs of somewhat similar chemical and
physical properties The degree of similarly of properties between HAPs was used as the guide in
designating Potential methods in those cases.
609
-------
For HAPs for which 110 Applicable or Likely methods were found, further searches were conducted
beyond the review's outlined above. For such HAPs, detailed literature searches were conducted using the
files of Chemical Abstracts Service (CAS) and the National Technical Information Service (NTIS). The
computer searches were not restricted to English language publications. In all method searches and reviews,
the chemical and physical properties compiled in this study were valuable. The quantitative similarity of
properties such as vapor pressure, solubility, and reactivity of HAPs was used to suggest Likely and Potential
methods, and the degree of similarity of properties determined the choice between designation as a Likely or
Potential method.
Detection limits or ranges of measured concentrations were indicated for each method and HAP as
reported in the respective methods. Supporting information such as the approximate sampled air volume was
also compiled An effort was made to indicate the detection limit for at least the most fully developed
method(s) for each HAP, but detection limits were not estimated when not explicitly stated in the method
The detection limits reported were meant primarily as a guide to the relative capabilities of the various
methods. Reference and method citations in the methods survey were aimed at providing the user of the
survey with enough information to review at least the basics of the identified method, and to locate farther
information if needed. No effort was made to compile all possible information on each method.
RESULTS
HAPs Properties
The first result of the survey of HAPs properties was the assignment of HAPs to the various volatility
classes, using the vapor pressure criteria discussed previously. The 189 HAPs were categorized into VVOCs
(15), VOC (82), SVOC (64), NVOC (5), VV1NC (6), V1NC (3), SVINC (2). and NVfNC (12), where the
numbers of HAPs in each class are shown in parentheses. HAPs that are actually compound classes were
categorized on the basis of the most volatile species likely to he present in ambient air. The volatile and
scmivo'.atile compound classes comprise the majority of the 189 HAPs. with organic compounds (166
chemicals) predominating over inorganic compounds (23 chemicals).
The project final report4 presents the complete results of the properties survey, in two different
tabular forms. The first table lists the 189 HAPs in the same order as in the CAAA, with the HAP name,
CAS number, molecular weight, volatility class, vapor pressure, boiling point, and water solubility. The
second table lists properties for VVOCs and VOCs only, and includes some of the information from the first
table, but also includes electronic polarizability, aqueous reactivity, and lifetime in ambient air.
HAPs Measurement Methods
The HAPs method survey is presented in the project final report4 in the form of a comprehensive
table that presents the 189 HAPs in the same order as they appear in the CAAA. An portion of the complete,
table is shown in Table 1 of this paper. For each 1IAP, the name, CAS number, and major volatility class
are shown. The ambient methods information is listed in successive columns for Applicable, Likely, and
Potential methods. The respective methods identified for each HAP are indicated by standard method
designations (e.g., TO-5, CLP 2, NIOSH 5514), or by citations to the pertinent literature (e.g., R 1. R-2.
etc.). The limits of detection for selected methods are provided, together with explanatory comments. The
methods and literature citations compiled in conducting the methods survey are cited in a reference list
following the complete methods table. HAPs consisting of compound classes were addressed by identifying
methods for the most and least volatile species of each class likely to be present in ambient air.
In all, this survey identified 183 methods pertinent to ambient measurements of the 189 HAPs,
comprising of 15 TO methods, 51 NIOSH methods, 30 OSHA methods, 3 F.PA screening methods, 4 CLP
methods, and 80 reference methods. A summary of the methods survey results was then prepared to examine
whether the most fully developed method for each 11AP falls within the definition of Applicable, Likely, or
Potential. This summary, presented in the form of a table in the project report/ lists each HAP together
with its volatility class assignment, and indicates the current status of methods identified for the IIAP. In the
summary table, likely and Potential methods are each sub-divided into two categories, one for methods
inferred on the basis of HAP chemical and physical properties, and the other for methods established for the
particular HAP. The total number of HAPs in each method development column was determined from this
summary table, with Figure 1 showing a graphical overview of the results.
Figure 1 shows that for 126 HAPs (two-thirds of the HAPs list), Applicable ambient measurement
methods were found. Figure I also shows that for 53 HAPs, Likely methods were found, but no Applicable
610
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methods. Most of these Likely methods were specific to the HAP in question, but for 7 HAPs the
identification of Likely methods was inferred based on 1IAP properties. For 6 HAPs only Potential methods
could be identified, and of those, 3 were inferred on the basis of chemical and physical properties. For 4
HAPs. no measurement methods could be identified at any level of development. The finding of 126 HAl's
with Applicable methods is consistent with a recent survey5'7 which found ambient data from urban areas in
the U.S. available for 115 of the HAPs. Note, however, that in considering Figure 1, the definition of a
Applicable method must be stressed. An Applicable method is one which is targeted for the indicated 1IAP in
ambient air, and which has been developed and documented to a reasonable degree. This does not mean thai
all Applicable methods have actually been used for ambient measurements of the indicated HAPs. or that all
sampling and analysis difficulties have been solved. An overly optimistic view of the state of HAPs
measurement methods could result if Figure I is interpreted without these reservations.
A more detailed evaluation of the methods summary was also conducted with respect to the most
developed methods available by class of HAPs. For most of the volatility classes. Applicable methods were
identified for the majority of the HAPs. In total. Applicable methods were identified for 109 of the '66
organic compounds, and for 17 of the 23 inorganic compounds However, for the 5 NVOCs and 2 of the 3
VINCs. r.o Applicable methods were found, in all volatility classes, most compounds with no Applicable
methods could be associated with one or more Likely methods. This result appears to suggest that for the
great majority of the HAPs, promising methods at least exist from which ambient methods may be developed.
However, for 6 HAPs, namely Acetamide (SVOC). 2-Acetylaminofluorene (NVOC). Benzolnchlorute
(SVOC), Chloramhen (SVOC). 1,2-Dipltenylhydrazine (SVOC), and N-nitroso-Hmethyl urea (VOC'i. only
Potential methods could be identified. Finally, for 4 HAPs, namely, Acrylic acid (VOC), Fthyl carbamate
(VOC), Hexamethy! phosphoranude (SVOC), and Titanium tetrachloride (VINC). no methods of any kind
were identified.
SUMMARY AND RECOMMENDATIONS
For 126 of the 189 HAl's. measurement methods designed for use in ambient air were identified.
Must, but not all, of these methods have actually been used for ambient measurements of the pertinent HAPs.
For 53 other HAPs, measurement methods were identified which are likely to be applicable to ambient air
after some further development. Based on these observations, ambient measurement methods appear to be
achievable for the great majority of the 189 HAPs. For 6 HAPs. existing measurement methods would
require extensive further development before application to ambient air can be considered. Tor 4 HAPs, no
measurement methods in any state of development were identified. Cumulatively, these latter 10 HAPs
comprise the greatest gap in measurement capabilities for the HAPs.
Ir, terms of method development needs for the HAPs, the most cost-effective, approach would
probably be further development of the Likely methods that exist tor the 53 HAPs with no Applicable
methods. The definition of a Likely method means that a reasonable degree of further development should
result in a method applicable to ambient air. Of the 53 HAPs with only Likely methods, 44 are VVOCs.
VOCs, or SVOCs These three groups are the largest classes of HAPs, so further development of methods
for such compounds would be particularly beneficial. In addition, the large number of Applicable methods
already available for volatile and semi-volatile organics should enhance development of methods for additional
compounds Continued evaluation of measurement methods for all the HAPs would be worthwhile An
important goal of such an effort should be to consolidate and simplify the variety of methods available ir.to a
smaller number of well-characterized and broadly applicable methods. Further verification of HAPs methods
is needed, even fo: Applicable methods, particularly for the research methods identified.
The 10 HAPs identified previously for which only Potential methods or no methods were found
would seem to indicate the greatest current need for ambient method development. These 10 HAPs are
relatively unusual compounds, not normally regarded as ambient air contaminants and some arc highly
reactive and not likely to be present lor long in the atmosphere 1 There are no ambient air concentration data
for these 10 HAPs, and virtually no information on potential atmospheric reaction products.1 Consequently,
it is difficult to determine whether they or their reaction products cause a significant health risk in ambient
air. Method development should be pursued for these 10 HAPs, but should be prioritized based on
information on the emissions, reactivity and products of these HAPs. This approach will avoid spending lime
and resources on method development for a HAP or HAl's that arc, for example, too reactive (e.g., titanium
tetrachloride) or emitted in quantities too small to be present at measurable levels in the atmosphere. This
linkage of method development with other information should in general be valuable for all other HAPs.
-------
REFERENCES
(1) Kelly, T.J.; Muknnd, R., Spicer, C.W.; Pollack, A.I., "The Hazardous Air Pollutants: Their
Concentrations, Transformations, and Fate in Urban Air", Environ, Sci. Technol.. in press, May 1994.
(2) Keith, L.H.; Walker, M.M., "EPA's Clean Air Act Air Toxics Database. Volume 1: Sampling and
Analysis Methods Summaries", 1SBN-0-87371-R19-4, Lewis Publishers, Boca Raton, Florida (1992).
(3) Winberry, W.T., Jr., "Sampling and Analysis Under Title III", Environmental Lab.. June/July 1993.
(4) Kelly, T.J.; Mukund, R; Gordon, S.M.; Hays, M.J.. "Ambient Measurement Methods and Properties of
the 189 Title 111 Hazardous Air Pollutants". Final report to U.S. EPA/AREAL, Contract No. 6S-D0-
0007, Work Assignment 44, March 1994.
(5') Clements, J .B.; Lewis. R.G., "Sampling for Organic Compounds", in Principles of Environmental
Sampling. L.H. Keith, ed., American Chemical Society, Washington. D.C.. pp 287-296 (1987).
(6) Keith. L.H.; Walker. M.M., 'EPA's Clean Air Act Air Toxics Database, Volume II: Air Toxics
Chemical and Physical Properties", ISBN-0-87371-820-8, I.ewis Publishers, Boca Raton, Florida (19931.
(7) R.G. Lewis, U.S. EPA'AREAL, personal communication, January-March l'J94.
ACKNOWLEDGMENTS
This work was conducted by Battelle under the sponsorship of the U.S. Environmental Protection
Agency's Atmospheric Research and Exposure Assessment Laboratory (EPA/AREAL), under Contract No.
68-DO-0002, Work Assignment 44. The Work Assignment Manager was Dr. William A. McClennv. This
paper has not been subjected to Environmental Protection Agency review and thcrdorc does not necessarily
reflect the views of the Agency, and no official endorsement should be inferred. We gratefully acknowledge
the involvement and technical insight of Drs. McClennv and Robert G. I.ewis of EPA in the work.
Likely Methods:
¦ ac Applied in non-ambient air
(eg. workplace, stack)
126
Applicable
Methods:
Applied in ambient air
Likely Methods:
' Inie'rcd based on
properties
Potential Methods:
Applied lor compounds
in other media
Potential Methods:
Inferred based on
properties
Figure 1. Distribution of the 189 HAPs by the most developed type of ambient measurement
method currently identified for each IIAP.
-------
Table* 1 Partial listing of the ambient measurement methods table for the 189 HAPs presented in the project final
report.
Compound
CAS No.
Compd.
Class
Ambient Measurement Method
Limit of
Detection 2,3
Comment
Applicable*
Likely
Potential
Aceta Jehycte
/5-U7-0
WCC
TO-i>
TO 11
R-H'.A]
\0-b 1 ppbv TO-1":
1 ppfcv [14]: 30 pnrrv
Aeetamide
"6^5-5
lvoc~
"OSHACiM
IA62b; K-j7;
R -ci
fA6?£] not a vaiinnled melhsd; R
4/: metioc developed for
analysis of wnter
Aoe'.oriitnle
Yb-3b-3
voc
R-1. CLP-1A. i TO"j n
R-3
R-1: 1 ppbv
jAcetophenone
T3-B6-2
_ _____ _
CAP-?.'
~~ ~
CLP-2*: 37 np/m*
p.007 pobv)
P-Ar^ly'ainhof.uotenc;
53-96 3
NVOC
CSKACIM
[C065]
[0065]: net a valida'.sd Tie vied
* D^iynjIicT as an Applicable nwl.iod uces; not .lecessar iy imply cctificalion or approval fcy J.S. EFA as a i aintiien air measutemeril n:ethoo
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Direct Trace Analysis of Volatile Organic Compounds in Air Using
Filtered Noise Field Ion Trap Mass Spectrometry
Sydney M. Gordon, Patrick J. Callahan, and Donald V. Kmmy
Atmospheric Science and Applied Technology
Baltelle Memorial Institute
505 King Avenue
Columbus. OH 43201
There is increasing interest in Ihe development ol' field portable mass
spectrometers to monitor environmental pollutants in real time. A direct air
sampling filtered noise field (FNF) ion trap mass spectrometer has been evaluated in
the laboratory under controlled conditions with an environmental test chamber serving
as the source of the target compound mixtures at known concentrations. The FNF ion
trap technology developed by Telcdyne has been used with direct sampling interfaces
(semipermeable membrane; glow discharge ionization source) to measure nonpolar and
polar VOCs at trace levels. This ion trap is capable of true selective ion monitoring
and, when operated in the MS/MS mode, provides a unique means of simultaneously
isolating individual target compounds in complex mixtures with high sensitivity and
specificity. The device is small and light-weight, and can be easily deployed in the
laboratory or the field. Using the combination direct sampling/ion trap system,
experiments have been carried out to evaluate the specificity, sensitivity, response
time, and effects of relative humidity on the detection of 44 nonpolar and 15 polar
VOCs of environmental interest.
614
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A System lor (he Determination of Trace-Level Polar and Non-Polar Toxic Organic
Compounds in Ambient Air
Andrew Tiplcr, R.Dnng and H.Hoberecht
Fresh Aire Laboratory,
Perkin Hlmcr Corp.,
761 Main Avenue, Norwalk
Connecticut, 06K59-O2XO
arstract
A gas chromatographic system is described for the determination of toxic organic compounds in
ambient air. These compounds include all those specified within the U.S. EPA Compendium Method
I <) 14 and some polar additional analytes under consideration for the proposed TO 15 Method. The system
supports both on-line and off-line (passivatcd canisters and adsorption tubes) methods for sampling air --
providing a fully automated analysis. A key feature of the system is that liquid cryopen is not required for
either the analyte preconeentration or the subsequent chromatographic separation. Water management is
achieved by dry-purging an adsorbent trap upon which the sample analytes have been retained.
The performance of the system is demonstrated with conventional detection systems (electron
capture and flame ionization) and with a mass spectrometer.
INTRODUCTION
A companion paper [I] discussed the various aspects of water management associated with the
collection and analysis of ambient air. This paper examines the instrumental considerations of a system for
the analysis of volatile toxic organic compounds in air. Several key requirements identified for such a
system are listed below:
• Should be applicable to the U.S. EPA T014 target analytes and polar compounds proposed for the
pending TO 15 method
• Should support on-line and off-line (passivated canisters and adsorbent tubes) sampling methods
• Should enable sub-ppb detection limits
• Should be compatible with capillary chromatography
• Should eliminate the need for a liquid eryogen
• Should eliminate the effects of water
• Should be compatible with conventional and mass spectroscopic detection systems
INSTRUMENTATION
Operation
Figure I provides a schematic overview of the instrumental components of the system. This basic
configuration is intended to be used, with minor changes, both with conventional detection systems such as
flame ionization and electron capture and with a mass speetrometric detection system.
I he operational sequence starts with the air sample or the effluent from a heated adsorbent tube
being passed into an adsorbent trap held at a near-ambient temperature. The volatile organic compounds
are retained within the adsorbent trap along with some of the water within the sample. After analyte
preconeentration. a How of dry purge gas is passed through the adsorbent to remove most of the residual
615
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air sample
or tube
valve
column
I
purge gas /
detector
Figure 1. Overview of instrumentation
moisture. 'l"he adsorbent trap is then heated and a flow of carrier gas in the reverse direction backflushes
the analyles. using splitting if required, into the chromatographic column. Chromatography then
commences. The system is fully automated for on-line and off-line (canister and tube) analyses and is
designed to enable the next sample to be collected while chromatography of the current sample is still in
progress.
System with conventional detectors
Svstem description
Table 1 lists the instrumental conditions for a system that uses tlame ionization and electron
capture detection systems. Chromatographic separation is important with these detectors so a long, very
low phase-ratio column is used to retain the early cluting components at 40°C. To reduce the analysis time
a high carrier gas flow rate (5 to 6 ml/min.) is applied. Although this is not normally considered optimum
for chromatographic efficiency, the faster rate does result in a more efficient desorption of analyles from
the trap and thus improve the chromatography of the early eluting components. The system employs the
dry-purge technique described previously [1] to remove much of the water collected in the trap. Note that
no split is applied to the trap effluent as it passes into the chromatographic column.
Table 1. Experimental conditions for the system using conventional detectors.
Figure 2 shows typical chromatography from the system for 450 ml of a mixture of 10 ppbv TOl
target analytcs from a canister. Good peak shape is apparent for all the peaks and good chromatographic
separation is achieved for all components except m-xylene.'p-xylenc and o-xylene' 1,1,2.2-
tetrachloroethane. Table 2 includes a list of the analvtes and the quantitative precision exhibited by the
system over a series of repetitive analyses.
Thermal Desorption System
Adsorption Trap
Chromatograph
Column
Oven
Detector
Carrier Gas
Pcrkin Elinor AutoSystem
100 m x 0.32 mm x 5.0fim methyl silicone, Scientific Glass Engineering
40°C for 10 min., then 5rC/min. to 250"C, hold for 8 min.
a) Flame ionization at 300^
b) Electron capture at 300CC
Column effluent split 300:1 FIDrKCH
Pcrkin Elmer ATD 400
Pcrkin Elmer Air Monitoring Trap, 27-C during sample collection (15
min. at 30 ml/min.) and dry purge (3 min. at 30 ml/min..), 3IS°C
during desorption for 10 min. with no split
Helium at 2S p.s.i.g. (5 ml/min. flow rate through the column)
ItesuUs
616
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Table 2. Quantitative precision of the system for TOM analytes under different operating modes
yte
Analyte Name
% RSI) of Peak Areas,
% KSI) of i'cak Areas.
% RSD of Peak Areas,
FID/ECD & Canister,
MS & Canister,
MS & Tube.
(n=12)
(n=9)
(n-5)
1
Kreon 12
+9.75
I.91
2.85
7
methyl chloride
6.34
2.70
6.39
3
Freon 114
1.52
3.81
4
vinyl chloride
1.56
1.78
3.95
5
13-butmlieue*
3.118
2.35
13.01
6
bromomethane
23.63
9.51
16.55
7
ethyl chloride
10.56
5.88
5.71
s
Freon 11
+0.85
2.14
2.91
9
vinylidene chloride
1.117
3.31
5.54
10
dichioromcthane
1.33
4.60
7.68
11
3-chloropropene
1.31
3.33
6.50
12
Freon 113
10.70
3.71
3.01
13
1,1-dichloroethane
1.07
2.02
4.13
14
cis-1,2-(lii'hloroethylene
3.11
2.06
3.75
15
chloroform
+0.48
2.46
3.66
16
1,2-dichloroetliane
3.43
2.45
5.36
17
methylchloroform
¦10.70
2.03
2.50
18
benzene
0.75
3.88
5.68
19
carbon tetrachloride
+0.79
2.43
1.83
2(1
1.2-iliclilorn[)ro|iane
1.03
2.74
4.01
21
trichloroctllene
+11.65
3.57
4.05
22
cis-l,3-dichloroprupcne
1.63
¦7.89
17.57
23
trans -1,3 dichloropropene
0.76
9.64
17.83
24
1,1,2-trichloroethane
1.67
3.28
3.53
25
toluene
1.02
2.58
3.69
26
1,2-dibromom ethane
--0.55
8.54
14.73
27
tctruchloroethene
+0.57
1.98
1.12
28
chiorobenzene
1.02
2.37
4.14
29
ethyl benzene
0.49
2.12
4.16
30
m,p-xylenes**
0.39
2.S6
3.88
31
stymie
0.31
2.22
2.48
32
1,1,2,2-lelracliloroethane
rl.18
2.63
3.56
33
o-xylene
*"
2.03
3.84
34
ethyl toluene
0.62
2.15
3.21
35
1,3.5 trimethylbenzene
0.95
1.69
3.58
36
1.2,4-trimethyl benzene
1.18
1.81
2.78
37
benzyl chloride
2.73
1.69
4.55
38
m-dichloru benzene
1.68
2.76
2.36
39
p-dichlorobcnzenc
1.90
2.72
0.90
40
o-dichlorobenzene
2.29
1.33
2.04
41
1,2,4-trichIorobcnzene
5.59
2.05
1.27
42
hexachlorobutadicne
>6.08
2.89
1.37
LCD datu. all others in this column are from the FID
i,3-bu!.id'tcno is not inched in ihtr UStv'A i 014 ¦ i*.c of target i;i;i]yU^
* I hc.-e components cannot be separated on this column or by mass snectron.ctr> s:> l!u da*i is combined
*" 0-.\yleix* co-e!»tc> with l.I,2,2-tcirach!oroeth»ne and so cannot he qualified on the FID
617
-------
36-5 .
h PIC Chram«tORr«m
30-j
2 a—; s *2
-» U 16
1 4 1 13 I
* 1® i PS ,
¦a ii1.; J.- U-
:a.y
2$
1
J0 ; j
21 2C
22 27
iillll
ft i
: )t JS
w 17.M
1 i 40 41
I
A
2^0.3 BCD Chrcimtogra
3
" HO-j
-i ..
t * •
n
I "1
I ,
?
11 t ( - 1 ; 1 1 : i ; i • | ) 1 1 : 1 1 I 1 / 1 > 1 ¦ 1 . > ) 1 1 • I ; 1 1 1 1 1 | i 1 • i • 1 J . 1 ; i > 1 : i 1 1
Figure 2. Typical eliromatogram of 10 ppbv 1014 analvtes from system with conventional detectors. The
identities of the peak numbers are given in Table 2.
System with a mass spectrometer
System description
Table 3 lists the instrumental conditions for a system that uses a mass spectrometer as the
chromatographic detection system. The system is very similar to that for the conventional detectors. The
carrier gas flow rate must be restricted to approximately 1 ml/min. for efficient detector operation.
Chromatographic separation, however, is less critical as peaks may be discriminated by selective mass
chroinatograms. Therefore, to reduce both the flow rate and the analysis time, a shorter column of the sam
type is employed. The mass spectrometer is much less tolerant of water than the conventional detectors so
the amount of water is further reduced by taking a larger sample volume and applying a small split on the
trap effluent as described previously [1|. It was found that the carbon-based adsorbents used in the trap
generated carbon dioxide in use. To minimize this effect, the trap was heated to the lower temperature of
280°C with no apparent degradation in the shape of the early cluting peaks. The ion with m'z 44 was
excluded from the total ion ehromatograms to further reduce the effects of the carbon dioxide on the
visualized chromatography.
Tabic 3.Cxperimcntal conditions for the system using a mass spectrometer.
Chromatograph
Column
Oven
Detector
Thermal Desorption System
Adsorption Trap
Carrier Gns
Tube
Tube Desorption
Perkin Elmer Autosystem
SO m x 0.32 mm x S.Oum methyl silicone, Scientific Glass Engineerin
40°C for 10 min, then 5"C/min to 250:'C, hold for 8 mill
Perkin Elmer QMASS 410. scan acquisition mode, 31) to 300 a.m.u.
Perkin F.lmer A 1 11 400
Perkin Elmer Air Monitoring Trap
a) Canister sampling: 27°C during sample collection (50 min at 20
ml/min) and dry purge (3 min at 30 ml/min)
b) Tube sampling: 27°C during tube desorption/dry purge (10 min i
ml/min)
28G°C during trap desorption for 10 min with 6:1 outlet split
Helium at 5 p.s.i.g.
Perkin Klmer Air Monitoring Sample Tube
28t)°C for 10 min at 30ml'min desorption flow
618
-------
Results
Figures 3 and 4 show typical total ion chromatograms from the system for 1000 nil of a mixture of
10 ppbv TOM target analytcs from a canister and a number of adsorbent tubes (loaded from the same
canister) respectively. Good peak shape is apparent for all peaks upon a clean, flat baseline signal,
IJj
aU
,i/L> w
Figure 3. Typical total ion chromatogram of 10 ppbv TOM analytcs from canister sample
voc t>wb» B?res?7fi :i/ t
rhr* -rsr rciiwsrr —
"•I -m* t1mn
JAC T(«-«r—~K7Y~ET77?,—TT7itl>'^A JO SV
tan rv rkin
JoJiili
i m #> io i-« iy i/ 3o gt b< Ba ga 3a as «t 3/ // -* 1 «* on jj
igurc 4. Typical total ion chromatogram of 10 ppbv TOI4 analytcs from tube sample
One concern to many analysts is equivalency between canister and tube sampling. Figure 5 shows
plot of absolute areas, for selective ion peaks, for both canisters and tubes. Good agreement between the
/o sampling methods is evident.
619
-------
2500000
'500000
5f-r**c
¦ TUBE
~ CANiSTFR
H
iJEmw
IlllliJli
mi.
* 2 3 « 5 6 7 « 9 (0 11 1? 13 14 IS 16 17 IS 19 20 21 2" 23 24 ?5 ?6 27 2e 29 3C 3* 32 33 35 3S 36 3? 3? 30 4(1 <1 4?
Analyte #
Figure 5. Comparison in analyte recovery- between canister sample and tube sample. The analyte identities
are given in Table
A second concern is the generation of artifacts or carry-over effects. Figure 6 shows
chromatograms (same scale) of two analyses of the same tube in succession. No artifact or carry-over
effect is apparent in the second ehromatogram.
F 1st Resorption
"1,1k iUl.jisl.)j.ii
2nd desorption
i-
rt3
i
s
i
..""75"— ?*•".- iv"5T. fi-i, jk^TT- , i
Figure 6. Lack of artifact and carry-over effects from an adsorbent tube
Table 2 includes the quantitative precision for samples taken from canisters and tubes. In all case
these values are less that 20% and in most cases they are less than 5% and are very similar to those
obtained from the conventional detector system.
Figure 7 shows selective mass chromatograms of a - 2 ppbv mixture of T014 analvtes. These e£
eluting analvtes are the 'worst-case' components for detection limits because of their reduced response
factors and because of increased background noise (because of traces of water and carbon dioxide). The
chromatograms clearly show that detection limits will be below the 1-ppbv level.
620
-------
j ^ vinyl chlor'rit
j5yi-_3r.itai* 1 Sit12IU JLntZEZ. t eiwS
) ' mrlhyl rJt'orirtB
SEniar2SK3X-M5r_
j jFrenn 1?
"_jM"iu dJTnjuct^un~.SUXGZT .
as-j / \ /\ Frten *14
ioO-JXC * ""
Figure 7. Selective mass chromatograms of early eluting TO 14 analytes at 2 ppbv from a canister
Figure S shows normalized plots of detector response versus volume of sample up to 2000 ml.
These data prov ide an indication of the retention capabilities of the adsorbent trap and also an indication of
the system's quantitative linearity. All the data appears satisfactory except for methyl chloride, methyl
bromide and 1.2-dibromotnethane. These analytes are known to be highly reactive and are known to
readily hydrolyze in water at low temperatures |2^3J. The effect appears to be less pronounced with the
volume adopted for this analysts (1000 mi).
-o
50.00%
0.00!
10 I
13 H 11-
1 > 3 4
' 8
Analyte tt
igure 8. Normalized plots showing variation in response with sample volume from 10 ppbv T014
canister mix. The analyte identities are given in Table 2.
Figure 9 shows a total ion chromatogratn of several polar analytes at the 10 pphv level extracted
oin an adsorption tube. Note that even methanol is easily visualized.
621
-------
i aiQDOQI
meiii
V
vinyl acetate
ethanol
\ aeetonltrlle mtbe
V / acetone \
, t ^ 2-propanol \
t j 4 ^acrylonitrlle^
JpyJUr .. O
1-butanoi
m#k \ benzene
ethyl aery lata
I ethyl acetate \ |Jt ®thyl aery late J
LljU 1
toluene
" i ,
Figure 9. ~10 ppbv polar analvtes from an adsorption tube
Figure 10 shows chromatograms of an ambient air sample in which the presence of methyl t-butyl
ether (MTBF.) is suspected. Figure 11 shows the mass spectrum of the highlighted peak that was easily
confirmed to be MTBE.
~ -ff^grt^^—jarra^Ta-Tpfa
Selected Mass Chromatogram (m/r * 73)
Total Ion Chromatogram
m
y \ a
•w
d
Figure 10. Chromatogram of ambient air taken on-line at Wilton. Ct on 2/21/94
Av«r«M-*H
Figure 11. Mass spectrum confirming identity of MTBE peak
a?..
622
-------
CONCLUSIONS
These data demonstrate the practical application of a multimodc instrumental system for on-line
and off-line (using canisters or tubes) sampling methods. The extraction and preconcenlralion of analytes
from the air and the subsequent chromatography is performed without the need for a liquid cryogen. The
dry-purge technique coupled with, a small desorption split, removes sufficient water to enable detection by
mass spectrometry. The dry-purge does not exclude polar analytes from the analysis and as a result,
compounds such as MTBE have been detected at low levels in ambient air.
REFERENCES
1. Tipler, A.; "Water Management in Capillary Gas Chromatographic Air Monitoring Systems",
submitted for the J'roceedings of the 1994 U.S EPA'AX IV MA Symposium on Measurement of Toxic
and Related Air Pollutants. Air and Waste Management Association: Durham, 1994
2. Encyclopedia of Chemical Technology, Third Edition., Kirk-Othmer, Ed.; Wiley (nterscicnce, 4, pp
251
3. Encyclopedia of Chemical Technology, Third Edition., Kirk-Othmer, Ed.; Wilcv Interscicncc, 5. pp
670
-------
Water Management in Capillary Gas Chromatographic Air Monitoring Systems
Andrew Tipler
Fresh Aire Laboratory,
I'erkin Elmer Corp..
761 Main Avenue, Norwalk
Connecticut. 06859-0280
ABSTRACT
Capillary gas chromatography is an excellent technique for the speciated quantitation of low-level
volatile organic compounds (VOCs) in ambient air.
Although GC detectors have excellent sensitivity, some sample pre-concentration will be necessar
to enable detection of VOCs at sub-ppb levels. This process normally employs u cooled and/or adsorbent
trap to retain the analytes from a large volume of sample air. For very volatile VOCs, a very retentive trap
is used and this may also retain water present as vapor in the sample. This trapped water causes significan
problems with the chromatography and detector operation and methods must be sought to remove it or
eliminate its effects.
This paper investigates the magnitude of the problem and examines the various alternatives for
managing the trapped water. The application of some of these techniques is demonstrated in a method for
the determination of volatile polar and non-polar toxic organic compounds in ambient air.
INTRODUCTION
This paper is intended to serve as an introduction to a companion paper f 1 ] to be presented and
published in the same forum. It is designed to consider the various aspects of water management and to
provide the basis for practical instrumentation to perform analytical methods such as the U.S. EPA
Compendium Method TO 14 [2] and proposed polar analvtes to be included in the pending T015 method
[3].
The first questions to address in considering water management, arc:
• how much water is collected
• what happens to water inside the analytical system
• what options are available to remove water
Amount of water in the air
The amount of water in the air sample depends on three factors:
• Sample humidity
« Sample temperature
• Sample volume
The first two of these, cannot be controlled by the analyst as they depend on climatic conditions.
The analyst is able, however, to choose the volume of sample to be collected. The main factor that diet:
the amount of sample to be taken is the detection limits of the gas chromatographic detection system be
used. For typical detectors this means that a sample, volume of 100 ml to 1000 ml must be taken in ordf
624
-------
collect sufficient mass of the analytcs to be detected. Figure I shows a plot of the water content of air at 75
% and 100 % relative humidity (R.H.) over a range of temperatures [4],
Tliis plot shows that, for example, if a 420-ml sample was taken ut 20 nC at 75 % R.H.,
approximately 6 mg of water also would be collected.
100 A R.H
- 75% R.H
0 10
Temperature *C
Figure 1. Water content of air at 75 % and 100 % R.H. over a range of temperatures
Effects of water
A typical capillary column requires a gaseous sample volume of about 50 pi at its inlet for efficient
operation. This means that the analytes in the sample must be preeoneentrated by a factor of about 10,000
prior to chromatography. This preconcentration is readily effected using a trapping device as shown in
Figure 2. The trap may be cooled or packed with an adsorbent or both of these in order to retain (he
analytes as the sample is drawn through. A cooled trap will retain most of the moisture from typical air
samples as a result of simple condensation. Figure 3 shows the amount of water that would be collected
from a range of sample volumes on an unpacked trap cooled to various temperatures.
Imp
detector
r-1
air sample
igure 2. Overview of air preconcentration technique
u
gas chromatographic coljmn
-------
Volume of Air, (ml)
Figure ?. Condensation of water from air at 20 °C and 75 % R.H. onto a trap cooled to a range of
temperatures
If no efforts are made to reduce this water, it may cause significant problems in the analy sis as
shown in the list below:
• Potential Blockage of Cold Trap
• Possible Reduction in Trapping efficiency
• Possible Reduction in Desorption Efficiency
• Disturbance in Chromatographic Carrier Flow
• Spurious Chromatographic Peaks
• Smearing of Chromatographic Peaks
• Degradation of Chromatographic Column
• Detector Quenching or Degradation
• Obscuration of Peaks of Interest
Options for water reduction
Hifih trap temperature
The easiest way of preventing the condensation of water within the trap is to maintain it at a
temperature above that of the sample during collection. To retain analytes at such a temperature, the traj
must be packed with a suitable adsorbent.
Hydrophobic adsorbents
There arc many adsorbents currently available from a variety of suppliers that have been used
successfully by many analysts for sample collection without experiencing problems with water. These
have been generally applied to components less volatile than n-C4 [5,6]. Analytes such as those specifi
in the T014 method f2] require stronger carbon-molecular sieve based adsorbents that are slightly
hydrophilic and will retain significant amounts of water.
626
-------
Taking smaller volumes of sample will directly reduce the amount of water entering the analytical
system. Although this may address problems associated with ice formation in cold traps, the ratio of the
amount of water to analyte (typically 1,000.001): 1) will not he reduced. More sensitive detection systems
will be required to detect the lower analyte levels and. if these are sensitive to water, problems may still he
experienced in handling chromatographic peaks that co-elutc with the water. Collecting samples at flows
below about 5ml/min may be unreliable and introduce additional errors into the analysis. Thus taking
small volumes may not be possible in instances where long sampling times are required to determine time-
weighted average analyte concentrations.
Condensation
Water w ill be removed from the air sample by condensation if it is taken below the dew point. This
can be achieved by lowering the sample temperature or increasing the sample pressure. I towever, it is also
possible for target analytes to condense with the water or for them to partition into the water and so
causing quantitative errors as a result.
Sample Splitting
With a scmi-hydrophilie adsorbent, at above-ambient temperatures, the trap may become saturated
with water after, tor example. 500 ml of air have passed through it during sample collection. If further
sample is taken, the amount of water will not increase but the amount of analyte will increase. This has the
effect of reducing the ratio of water to analyte on the trap. By splitting the effluent from the trap during
thermal desorption, the amount of water entering the column is reduced to a more practical level while
maintaining the required analyte levels.
Semi-pcrmeablc ijiembranc_dryers
Pertluorinatcd membrane dryers (NAFION, Du Pont) have been successfully employed in the
TOM [2] and Ozone Precursor [7] analyses. They are easy to use and give excellent performance
especially with aliphatic and aromatic hydrocarbons [8], They can. however, remove polar analytes from
an air stream as shown in Figure 4.
ji) Nn NAFION Dryer
methyl l&opropyl ketcne
n-buUnoi
i
b) Jn-Lfnc NAFION Dryer
3-prone
cyclohexanon
n-hew*no
ly:&rc~$3^S. \
igtjre 4.1.oss of Polar Analytes on NAFION Dryer
627
-------
Inorganic desiecants
Inorganic desiccants have been successfully applied by several workers [10] in abstracting water
from air streams. They tend to be selective in their application and quickly become saturated with water.
Dry purge of the adsorbent
When a semi-hydrophilic adsorbent is used for sample collection at above-ambient temperatures,
the residual water left by the sample may be reduced by passing a dry gas through the adsorbent and out to
a vent [1,9,11 j as shown in Figures 5a to 5c. The only requirement is thai none of the analytes should cluti
from the trap during this purging process.
sample
a) Sampling
purge gas
cool
b) Dry purge
hot
c) Desorption
carrier
gas
b'igure 5. Operational Sequence of Dry Purge Technique
*OC Trauai.: R3TES026 3./2S/34 20 41:40
100jp
for Run 3340783
o«xyl*ne
dichloft»nelh«nt
Loluon*
h«*«c More buUd lent
\
i
-------
This approach offers the maximum flexibility in terms of sample volume, sampling method (on-
line, passivated canister or adsorption tube), analyte range (non-polars and polars) and detection systems.
The dry purge teeluiique may also be combined with trap outlet splitting as required.
The practical application of the water removal technique for a complex and demanding analyte
range is shown in Figure 6. This shows a total ion chromatogram of TO 14 and polar analytes using a
combination of dry purging and trap outlet splitting obtained using the conditions listed in Table /. Figure
7 shows some selective mass chromatograms that illustrate that analytes such as methanol, acetone and
methyl t-butyl ether can be easily visualized and quantified using this technique.
CTGL' Tra.-U. m7IYFY«72K T7TJ».j -* i—_=- ~r _=r- _=; _=r =r- ¦=-r"=-1=—¦ ¦ L. -±=-T*~
—
ton nnytwow SJLuaiX* .jSZTUi** —ts^x.—fljju ,
methyl t-buty! ether
.acetone
,imi> 5_» anal
methanol
total {on chromatogram
Figure 7. Selective mass chromatograms of early eluting polar analytes in -TO ppbv mixture of T014
target analytes and added polar compounds
table 1 .Fxperimental conditions for the determination of T014 and Polar Analytes in ambient air using
the dry purge technique.
Chmmatograph
Perkin Elmer Autosj stem
Column
50 m x 0.32 mm x 5.Ufim methyl silicone, Scientific Glass Engineering
Oven
40°C for 10 min., then 5^0'min to 2503C, hold for 8 min.
Detector
Perkin Elmer QMASS 910, scan acquisition mode, 30 to 300 a.m.u.
Thermal Dcsorption System
Perkin Elmer ATI) 400
Adsorption Trap
Perkin Elmer Air Monitoring Trap, 27°C daring sample preconcentration
and dry purge (10 min.), 280^C during dcsorption with 6:1 outlet split
Carrier Gas
Helium at 5 p.s.l.g.
Sample
Perkin Elmer Air Monitoring Sample Tuhe Loaded with 1000 ml (50min at
2U ml/min) 10 pphv TO 14 analyte mix with added polar analytes
Sample Resorption
280 C for 10 min. at 30ml'min desorption (low
Further experimental details of the instrumentation, its operation and performance are given in the
ompanion paper fl |.
CONCLUSION
A method has been developed that offers potential for the gas chromatographic determination of
oth non-polar and polar analytes in ambient air without the inherent problems traditionally associated
'ith water even when using a mass spectrometer as a detector.
629
-------
REFERENCES
I. Tipler, A., Dang, R. and Hoberecht, H.; "A System for the Determination of Trace-Level Polar and
Non-Polar Toxic Organic Compounds in Ambient Air", submitted for the Proceedings of the 1994 US
EPA/A&WMA Symposium on Measurement of Toxic and Related Air Pollutants. Air and Waste
Management Association: Durham, 1994
Winberry, WJr., Murphy, N.T. and Riggin, R.M.; Compendium of Methods far the Determination
of Toxic Organic Compounds in Ambient Air; U.S. Environmental Protection Agency: Research
Triangle Park. 1988; pp 467-583
3. Personal communications with McClenny, W.A. and colleagues at U.S. Environmental Protection
Agency. Research Triangle Park, 1993 and 1994
4. American Society of Refridgeration Engineers' Brochure on Psychrometrv, 1947
5. "Volatile organic compounds in air - Laboratory method using pumped solid sorbent tubes, thermal
desorption and gas chromatography". Methods for the Determination of Hazardous Substances; - 72,
U.K. Health and Safety Executive, 1992
6. Ciccioli. P., Cecinato, A., Enzo, B.. et al.; HRC & CC, 15, 1992, pp 75-84
7. "Enhanced ozone monitoring network design and siting criteria guidance document", U.S. EPA, Offic
of Air Quality Planning and Standards, EPA-450/4-91 -033, 1991
8. Broadway, (}.M, Tipler, A., and Seclcy, I., "The application of an automated non-cryogenic system f<
the determination of volatile organic ozone precursors in ambient air", in Proceedings oj 15th
International Symposium on Capillary Chromatography, Huethig, Riva del Gurda, Italy, 1993, pp 63'
644
9. Tipler, A., Broadway, G.M, Cole, A., "A system for the determination of trace-level toxic organic
compounds in atmospheric samples", in Proceedings of 15th International Symposium on Capillary
Chromatography, Huethig, Riva del (iarda, Italy, 1993, pp 586-592
10. Schmidbauer, N., and Oe'.imc. M„ HRC & CC, 9, 1986, pp 502-505
II. VlcClcnny. W.A., Oliver, K..1). and Daughty, E.H.; "Dry purging of solid adsorbent traps to remove
water vapor before thermal desorption of trace organic gases"; awaiting publication
630
-------
The Perkin-EImer ATD-400 System for Monitoring of Ambient
VOC Ozone Precursors
Paid Kadenheimer
Consolidated Sciences Corporation
I'll6 Southmorc
Pasadena. TX 77502
John (lihich
Texas Nalural Resource Conservation Commission
P.O. Box 13087
Austin, TX 78711-3078
Larry Ogle
Radiau Corporation
P.O. Box 201088
Austin, TX 78720-1088
The systems described were used in the Texas Natural Resource Conservation
C ommission (TNRCC) Coastal Oxidant Assessment for Southeast Texas
(COAST) program. Continuous VOC monitoring programs were implemented in June
through November of this year in Houston. This Perkin-EImer developed monitoring
system included a dual capillary column chromatographic application in an 8700 GC
vvitli a modified ATD-400 sampling system. The resulting separations are monitored
and quantified using Turbochrom (ver. 3.2) chromatographic data handling software.
The key clement to this system is the thermal desnrption device which is capable of
concentrating VOCs from ambient air then desorbing them directly to the gas
chromatograph on a continuous cycle. The ATD-400, unlike other similar devices,
contains an activated caibon tiap which is electrically cooled during collection via
Peltier technology. This eliminates the need for cryogenic liquids or compressed air
(vortex) for sample collection and makes unattended field operation more feasible (han
previous systems. The entire system is integrated to provide a completely automatic
sample collection cycle, gas cinematographic analysis and data collection, reduction
arid report generation. Reliability and repeatability data suggest that the system is
robust. Good correlation between systems and quality audits confirms data from the
manufacturer. Modifications which are being implemented to the chromatographic
system, system sites, and operator behavior to enhance the system performance will
also be presented.
-------
System Operation: Continuous Volatile Organic Compound Air
Monitoring of 56 Ozone Precursors with the Perkin-Elmer 8700 GC.
and Automatic Thermal Desorption System
Paul Radenheimer
Consolidated Sciences Corporation
1416 Southmore
Pasadena, TX 77502
John Gibich
Texas Natural Resource Conservation Commission
P.O. Box 13087
Austin. TX 78711-3078
l.arry Ogle
Radian Corporation
P.O. Box 201088
Austin, TX 78720-1088
As part of the. Coastal Oxidant Assessment for Southeast Texas (COAST)
program, two sites were chosen by the Texas Natural Resource Conservation
Commission (TRNCQ and equipped with a Perkin-Elmer VOC system composed of
the 8700 Gas Chromatograph, ATD-400 Automatic Thermal Desorption and
Turbochrom 111 Data system on DEC; computers. The systems were equipped with a
dual capillary column application capable of resolving 56 distinct target ozone
precursors. These components were separated and quantified on an hourly basis 24
hours each day. Each system generated 96 data files and approximately 30
documentation files each day totaling nearly 3 megabytes of information. The system
was fully automated and monitored rigorously via high-speed modem communication.
The modem communication proved to be essential in the handling of the large volume
of data generated each day. A fully automated data transfer system was developed to
allow unattended file archiving thus eliminating many problems associated with
manual handling of files and facilitating the rapid evaluation of the data. This paper
will identify the major issues in operation and maintenance of these systems (not
including the chromatographic application). Problems which were encountered can be
subdivided into two categories, a) hardware system problems such as power failures,
equipment malfunction and temperature/humidity fluctuations, and b) software issues:
capability/incompatibility, bugs, communication problems and a plethora of computer
or computer-related issues (confusion).
-------
SESSION 13:
APPLYING TOTAL HUMAN EXPOSURE
METHODOLOGIES TO ADDRESS
ENVIRONMENTAL HEALTH ISSUES ALONG THE
U.S.-MEXICO BORDER
Session cancelled.
-------
Intentionally Blank Page
-------
SESSION 14:
PARTICLE STUDIES
-------
Intentionally Blank Page
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The Role of Size-Dependent Dry Deposition of Sulfate Aerosol in
a Three-Dimensional Eulerian Air Quality Model
Francis S. Binkowski'
Atmospheric Sciences Modeling Division
Air Resources Laboratory, NOAA
Mail Drop 80
Research Triangle Park, NC 27711
Uma Shankar
MCNC
P.O. Box 12889
Research Triangle Park, NC 27709-2889
The Regional Particulate Model, a three-dimensional Eulerian air quality
model, was developed to investigate aerosol particle issues of importance to the U.S.
EPA and to meet the demands of the Clean Air Act Amendments of 1990. In addition
to aerosol dynamics such as growth and coagulation, the model includes
photochemistry, transport, and deposition. A new formulation of dry deposition as a
function of Ihe aerosol size distribution has been incorporated into the model, 'lhis
formulation allows for the representation of dry deposition of total particle number and
total particle mass by deposition velocities specifically formulated for these two
quantities as a function of particle size. Results for the dry deposition of sulfate mass
from the new model will be compared with those from the Tagged Species
Engineering Model (McHenry, el al., 1992) for a variety of local conditions. The
behavior of the aerosol size distribution responding to the new formulation will also
be discussed.
McHenry, J.N., Binkowski, F.S., Dennis. R.L., et al.
(1992) Almos. Environ., 26A: 1427-1443.
'On assignment to the Atmospheric Research and Exposure Assessment
Laboratory, U.S. EPA.
-------
Size Distributions Parameters and Hygroscopic Growth of
Aerosol Particles Bearing V
J.M. Ondov, !•'. Divita, and T.L. Quinn
Department of Chemistry and Biochemistry
University of Maryland
College Park, MD 20742
Size-segregated submicromcter aerosol particles were collected with
microorificc impactors (MOl) at three sites in the heavily urban, but nonirdustrializcd
Washington, DC. metropolitan area, during a 40-day period in August and September
of 1990, when atmospheric V was principally derived from commercial and utility oil
combustion. Results for 34 MOl samples, analyzed for V by instrumental neutron
activation analysis, were fit with a least-squares technique which used impaclor
calibration data to determine log-normal distribution parameters, i.e., mass median
aerodynamic diameter (mmad) and geometric standard deviation (ct,) for tine-particles
bearing V. The median mmad for 19 College Park (CP) samples was 0.361 + 0.006
^m. At this situ mmads for samples collected in the absence of rain and with V
concentrations >0.61 ng/'ml increased continuously with increasing RH from 56 to
7y% according to the equation d,,~ = 0.02168 + 0.00325 ¦ ln(a„.) - 0.0130. Mmads lor
samples collected at the other sites were characteristically smaller than those
determined at CP at comparable RH, possibly, due to the influence of nearby oil-fired
boilers. Vanadium aerosol data for rural Chesapeake Bay sites will also be presented.
638
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Measurement and Speciation of Gas and Particulate Phase
Organic Acids in an Urban Environment
¦Joy Lawrence and Ptiros Koulrakis
Harvard School of Public Health
665 Huntington Avenue
Boston, MA (12115
Organic acids arc important contributors to ambient acidity, in both gas and
particulate phase. Particulate phase organic acids represent an important fraction of
organic particulate matter. This paper presents the results of a field study conducted in
Philadelphia, PA, during the summer of 1992, to measure (he concentrations of gas
and particulate phase organic acids. Formic acid was found to be the most abundant
gas phase organic acid, with acetic and propionic acids detected at lower
concentrations. Organic acids constituted approximately 5% of the particulate fine
mass, whereas sulfate and ammonium constituted 40% and 15%, respectively.
Dicarboxylic acids and even-carbon monocarboxylic acids were found to account for a
large fraction of particulate weak acidity; odd-carbon monocarboxylic acids accounted
for a very small fraction. The pronounced even carbon preference of the
monocarboxylic acid distribution suggests a biogenic origin; the dicarboxylic acid
distribution may suggest that primary emission is more important than photochemical
production. This paper discusses the measurement and analytical techniques used in
this study and the chemistry and origins of organic acids.
639
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Philadelphia Diesel Particulate Matter Monitoring Study
Breda Phillips
OAQPS/U.S. EPA, MD-15
Research Triangle Park, NC 27711
Thomas Lumpkin
AREAL/U.S. F.PA, MD-76
Research Triangle Park, NC 27711
Mike Pleasant
ManTcch Environmental Technology, Inc.
P.O. Box 12313
Research Triangle Park, NC 27709
ABSTRACT
This paper summarizes the results of a monitoring study conducted in Philadelphia to learn
more about the contribution of diesel particulate emissions to particulate matter concentrations in
urban areas. Saturation monitors and a dichotomous sampler collected data for 28 days in two
traffic corridors. The results indicate that higher particulate matter concentrations occur where there
are higher bus counts and traffic volumes. The daily operation of the study is described and average
bus counts and quality assurance results are discussed. The monitoring method used in this study
proved to be reliable with a 95% data capture of ambient particle mass.
INTRODUCTION
Because of the nature of their use, heavy duty diesel buses are predominately found in
heavily populated metropolitan areas. They discharge up to 70 times more particulate than gasoline-
powered vehicles, thus contributing to known air quality problems and a widespread consensus on
the health risks associated with exposure to their emissions.1 During the period of October 19 to
November 18, 1993, a study was conducted to monitor diesel particulate emissions in and around
the Center City section of Philadelphia, PA. The purpose of this study was to monitor particulate
emissions in an urban street canyon-like area influenced by diesel bus traffic. This paper
summarizes the methodology used and the particulate matter data obtained during the study period.
EXPERIMENTAL
Sampling Sites
The monitoring network consisted of 15 saturation monitor sites (one collocated with a
dichotomous sampler) in the City Hall/Dilworth Plaza section of Philadelphia (see Figure 1). An
additional saturation monitoring site, Site 16, was located approximately six blocks south of the City-
Hall area. Sites 1 through 8 are primarily located along Market Street where it meets East Penn
Square. Sites 9 through 15 are located along the Chestnut Street Transitwav which functions as a
one way dedicated bus corridor. These two areas, referred to as Market Street and Chestnut Street,
represent typical urban streets bordered on both sides by tall buildings, thus creating a corridor or
canyon effect. Site 16 would be considered a non-canyon monitoring site.
All saturation monitors were lwng on streetlight poles at 3.2 to 3.4 meters above the
sidewalk level and generally within 3.0 meters from the roadway. Collocated saturation monitoring
sites were Sites 1, 4, 10, and 14. The dichotomous sampler and a saturation monitor were located
at Site 2 at the corner of Commerce and Juniper .Streets.
640
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Saturation Monitor and Dichotomous Sampler
The saturation monitor is a non reference portable battery powered sampler that is often used
to determine approximate particulate matter concentrations in short duration studies. The Airmetrics
(Springfield, OR) saturation monitor was used to collect samples for measurement of particles with
an aerodynamic diameter less than or equal to a nominal 10 micrometers (PM-10). Samples were
collected on a 47 mm Pallflex (Putnam, CA) Teflon®- coated glass fiber filter. Panicle separation is
acliieved by impaction. The monitor operates at a flow rate of 5 L/min at ambient conditions. The
monitor is equipped with a programmable timer to automatically start and stop sampling.
The Anderson (Atlanta, GA) dichotomous sampler is a low-flow-rate (16.7-L'min) sampler
that divides the air stream passing the 10-^m inlet into two portions, which are filtered separately.
The sampler cuts the 0- to 10-/iin total sample into 0- to 2.5-^m (fine) and 2.5- to 10-urn (coarse)
fractions, which arc collected on separate 37-mm Millipore (Bedford. MA) Teflon® filters. The
coarse and fine fractions are combined to give a total sample.
Bus Counts
Bus counts were taken at the Market Street and Chestnut Street (note li on the map in Figure
I) areas over four days at four different time intervals covering morning and evening peak traffic
rush hours. Market Street has unrestricted two way traffic with approximately 115 to 150 buses per
hour during traffic rush hours. Muses on Market Street include both Philadelphia city buses and
interstate commuter buses. Chestnut Street is restricted to one-way Philadelphia city bus traffic with
approximately 25 buses per hour during traffic rush hours.
Sampling Schedule
The saturation monitors at Site 1 and Sites 3-16 were set on automatic timers to turn on at
2:00 p.m. and turn off the following morning at 10:00 a.m. The batteries and filter holders were
changed between 10:00 a.m. and 2:00 p.m. daily. Collocated saturation monitors operated for one-
week periods to obtain integrated samples at Sites 1, 4, 10, and 14. The dichotomous sampler and
the saturation monitor at Site 2 collected 24-hour samples Filter, filter holder, and battery changes
were performed daily around 9:45 a.m.
Filter Handling and Weighing
AH weighing was performed in the laboratory at Research Triangle Park (RTP) according to
liPA quality assurance specifications. After the initial weighing of filters for the saturation monitors
and the dichotomous sampler, the filters were placed in individual, labeled plastic storage dishes.
After sampling, the filters were placed in their original dishes and returned to RTP for final
weighing at the end of the study. The filters were weighed on a Cahn C-31 microbalancc (Cerritos,
CA) located in an environmentally controlled chamber. All filters were placed in the chamber a
minimum of 24 hours prior to both initial and final weighing.
RESULTS AND DISCUSSION
Saturation Monitor and Dichotomous Sampler Data
The PM-10 mean concentrations for saturation monitor Sites 1 and 3-8 (Market Street) and
Sites 9-15 (Chestnut Street) are presented in Figure 2. The average number of buses per hour
during peak traffic hours is also indicated for each area. Market Street PM-10 mean concentrations
range from 38.4 jug/rtr' to 48.2 Mg'1"3 with an average bus count of 130 buses per peak traffic hour.
Chestnut Street PM-10 mean concentrations ranee from 31.8 /xg/m3 to 34.0 figjm1 with an average
bus count of 25 buses per peak traffic hour. It appears that the higher PM-10 mean concentrations
in the Market Street area are related to the higher bus counts and volume of traffic. Site 16 is the
ion- canyon site with a mean concentration of 34.7 jig/m1.
The PM 10 concentrations for selected Sites 1.4,6,8.10 and 14 by sample day of week are
ihown in Figure 3. These sites represent concentrations in both the Market Street and Chestnut
641
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Street areas. During the study period, the measured PM-10 concentrations consistently fluctuate and
track each other regardless of site location. The PM-10 concentrations for weekends are
consistently lower than average weekday PM 10 concentrations.
The total panicle mass collected by the dichotomous sampler peaked at 70.4 fig'tn1 and
resulted in a mean concentration of 36.9 /xg'm\ The PM-10 mean concentration for the collocated
saturation monitor at Site 2 was 34.5 ftg/m\ When comparing the collocated saturation monitor and
dichotomous sampler PM-10 concentrations, 88% of the values agree within 20% of each other.
The dichotomous sampler fine fraction averaged 68% of the total PM-10 sample for the 28 sample
days.
Quality Assurance Results
The dichotomous sampler flow and saturation monitor flows were checked daily and
adjustments were made if necessary. Blank dichotomous filters, both fine and coarse, and normal
and field saturation monitor filter blanks were collected. There were no appreciable changes in the
before-study and after-study filter weights (less than 0.009% difference). Quality assurance in the
filter weighing procedure was also conducted and rccalibrations of the balance were made as
appropriate.
Saturation monitors were collocated for one-week periods at sites 1, 4, 10, and 14.
Comparative concentration results of the collocated monitors under ambient conditions indicate an
average percent difference of 5.1% between the main monitor and the collocated monitor.
The overall percent data capture for the study for both the saturation monitors and the
dichotomous sampler was 95%.
CONCLUSIONS
The results of this study confirmed that saturation monitoring can be a useful screening tool.
There was good agreement between the PM-10 concentrations measured by the dichotomous sampler
and its collocated saturation monitor. Furthermore, the saturation monitoring method used in this
study proved to be reliable for collecting atmospheric particle mass data (95% data capture overall).
The quality assurance practices conducted in this study resulted in a weighing precision thai, is well
within acceptable limits.
Based on the comparison of PM-IO mean concentrations at the Market Street and Chestnut
Street areas, it appears that higher PM-10 concentrations are measured where there are higher bus
counts and traffic volumes, thus more tailpipe emissions and particle resuspension off roadway-
surfaces
During the 28-day study period. PM-10 concentrations measured on weekends were
consistently lower than the average weekday, regardless of site location. Fluctuations in day-to-day
PM-10 concentrations were consistent for all site locations.
The PM-10 mean concentration at the non-canyon site is higher than the PM-10 mean
concentration for the Chestnut Street area. This may be due to the much greater volume of traffic-
thus tailpipe and resuspended particulate matter emissions, at the non-canyon site.
For the dichotomous sampler and its collocated saturation monitor, 88% of the measured
concentration agree within 20% of each other. Two-thirds of the total sample measured with the
dichotomous sampler is in the fine fraction for this study period.
Future monitoring studies may further our understanding of the impact of diesel emissions on
particulate matter concentrations. For example, ambient particulate concentrations and traffic
volumes collected using continuous sampling methods and video surveillance equipment would
provide real-time data for time-series analyses. Because of the renewed interest in fine particulate
matter concentrations in urban areas, consideration should be given to conducting saturation
monitoring studies using a 2.5-fj.m cut point indicator for collecting real time or diurnal data.
642
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ACKNOWLEDGEMENTS
This paper is based on work performed by ManTech Environmental Technology, Inc. for the
U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards and the
Atmospheric Research and Exposure Assessment Laboratory.
DISCLAIMER
Statements made in this paper are those of the authors and do not necessarily represent the
views of the U.S. Environmental Protection Agency or ManTech Environmental Technology, Inc.
REFERENCES
1. Zielinska, Dr. B ; Diesel Emissions: New Technology, Health Effects and Emission Control
Programs, Prepared for the Arizona Depanment of Environmental Quality by Desert
Research Institute, April, 1991; p 1.
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644
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Figure 2. Marker Street vs. Chestnut Street saturation monitor results.
T Th Sa M W F $ T Th $a M
Sample Day
Site 1
Silo 8 Site 10 Site 1 -1
-igure 3. Tracking daily concentrations for Sites 1. 4, 6, 8, 10, and 14.
645
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Diurnal and Elevational Variations in Ozone and Aerosol Concentrations in
New Hampshire's Class 1 Airsheds
1-. Bruce Hill. Appalachian Mountain (Hub, P.O. Box 298, Gorham, Nil 03581
George A. Allen, Harvard School of Public Health. 665 Huntington Ave., Boston,
MA 02115
ABSTRACT
Ozone and fine mass aerosol concentrations on New Hampshire's Mount
Washington, situated adjacent lo both the Presidential/Dry River and Great Gulf
Wilderness Class-I Airsheds, exhibit distinct diurnal and elevational patterns. These
patterns are attributed to regional pollutant transport dynamics, nocturnal atmospheric
stratification, mountain meteorological phenomena and scavenging. A well-defined
planetary boundary layer (PBL) forms at about 1 km elevation at night as demonstrated
by nocturnal ozone monitoring along the Mount Washington Auto Road. The PBL
provides an effective elevational barrier at night, isolating the valleys from the regionally
transported air pollutants present above the mixing layer. During the daytime, the PBL
breaks up due to convective processes and katabatic winds resulting from solar heating
in the valley. This process creates a diurnal mixing cycle with ozone maxima recorded
near mid-day in the adjacent valley. In contrast, fine mass concentrations arc higher at
the valley site, attributed to local source inputs, and the lack of strong nocturnal
scavenging processes, compared with ozone. How aerosol concentrations are related to
the PBL and how they are affected by diurnal mixing remains unclear largely due to
current sampling methods. Exposure to ozone is generally greater above treeline in the
two airsheds.
INTRODUCTION
The White Mountain National Forest (WMNF) and its two Class-1 Airsheds arc
located in northern New Hampshire about 200 kilometers north of the metropolitan
Boston area. The area experiences 7 million visits per year. Many visitors enjoy hiking
along the ridgclines of the Presidential Mountain Range above treeline with its abundant
rare arctic plant species. Mount Washington, easily accessed by its summit road and
public facilities, is centrally located between the Great Gulf Wilderness (0.5 km north
of Mount Washington) and Presidential/Dry River Wilderness (1 km. south of Mt
Washington) Class-1 Airsheds, providing an ideal location for assessing air quality
impacts. This joint AMC and HSPII study began in 1986 to examine the dynamics of
ozone and fine mass aerosols with elevation as a part of a hiker health study and to
provide baseline pollutant monitoring to protect the two Class 1 areas in cooperation
with the White Mountain National Forest.
Methodology
The AMC and HSPH ozone monitoring site on the summit of Mount Washington
in New Hampshire's White Mountain National Forest has operated during summer
months since 1987 in the Mount Washington Observatory at an elevation of about 1914
m.. Data from the site, audited monthly for quality assurance by the state of New
Hampshire Air Resources Division (NHARD) and FPA. is submitted to the F.PA AIRS
retrieval system through NHARD. An AID 560 portable chemilluminescent ozone
analyzer was used to acquire elevational ozone data on the Mount Washington Auto
Road. While the summit ozone monitor operates continuously from mid-May to mid-
646
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October, the standard analysis period is July/August Additional detail on ozone
monitoring methods may he found in Hill and Allen (1994). Data from the valley site was
provided by W. Manning of the University of Massachusetts
Aeid aerosol and fine mass aerosol monitoring is eondueted at a high and a low
elevation site using Harvard proloeol denuder samplers (Koutrakis £l aJ. 1988; Marple
et al. 1987.) Monitoring is also conducted during a standard July/August period. Daily
average fine mass and acid aerosol concentrations are taken from nominal 10 hour
daytime samples. The valley monitoring site is situated at the AMC Camp Dodge facility
at an elevation of about 451 m.. At this site fine mass (PM.s), acid aerosols and sulfate
data are collected. At the high elevation site, located at the AMC's Lakes of the Clouds
facility at 1.540 in., fine mass, sulfate and acid aerosol concentrations are measured using
techniques described in Hill and Allen (1993).
RESULTS OF THE STUDY
Ozone and Fine Mass Aerosols
Typically, higher ozone concentrations are recorded with elevation, on Mount
Washington. For the cumulative monitoring period (1987-1993), mean hourly ozone
during the standard July/August period was 45 ppb at the summit site and 30 ppb at the
valley site. Similarly, the maximum hourly average concentration recorded at the summit,
148 ppb, exceeded the National Ambient Air Quality Standard (NAAQS) in 1988. A
considerably lower 105 ppb maximum was recorded at the valley site in 1991. Similar
elevational relationships in the Swiss and Austrian Alps have been reported by
Samson (1978), Wunderli and Gehrig (1990), and Puxbaum £| a1 (1991). The top of a
visible haze layer beneath the summit of Mount Washington is located at the same
elevation as the PBL This haze is composed of fine mass aerosols with nominal 10-hour
daytime sample concentrated as high as 81 ug/m '. Chemical analyses suggest sulfate is
52-64% of the total fine mass aerosol and that sulfate is partially neutralized to
ammonium bisulfate.
Elevational Profile of Ozone
Elevational profiles oil Mount Washington (Hill and Allen, 1994) indicate
nocturnal atmospheric stratification. Radiationa! cooling forms a vallev-bottom inversion
layer. In addition, a second layer develops at about 1,000 m. elevation, interpreted to be
the PBL. Figure 1 are daytime and a nighttime ozone and temperature profiles for
August 3. 1993. The nocturnal profile demonstrates a steady increase in ozone from 26
ppb in the valley bottom to about 1,100 m. where the ozone concentration flattens out
at about 56 ppb. Note, also, the temperature inflection at the same elevation for the 5
am. run. This elevation is interpreted to be the PBI,. The presence of a visible early
morning layer below the summit, and a strong relationship between visibility and aerosols
supports this hypothesis. In contrast, the daytime profile indicates homogenous ozone
concentrations in the atmosphere from summit to valley due to mixing related to the
diurnal thermal cycle.
Diurnal Variations in Ozone on Mount Washington
Figure 2 shows average ozone concentrations for the summers of 1987-1993 broken
down by hour at the two sites. The summit curve (n-17,100 hours) exhibits higher overall
concentrations and is depressed (reversed) near mid-day. Peak ozone concentrations are
commonly recorded between midnight and 6 am at the summit. Based on 1988 data,
peaks compared for a I1SPH Newtown, CT site and the summit site indicate that ozone
travels north and reaches the WMNF after a time lag of about half a day under
647
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conditions of southerly airflow. This relationship, combined with higher concentrations
recorded at the summit site, suggest that ozone is regionally transported above the PR!,.
The base site curve (n-12,350 hours) shows a strong diurnal cycle with maxima near mid-
day. a pattern nearly identical to the solar heating cycle, and similar to patterns
described in the valley bottoms of the Swiss Alps (Wunderli and Gehrig. 1990.) The
valley diurnal cycle displays a similar pattern to urban diurnal cycles created by
photochemical reactions and the solar cycle. The mountain valley diurnal pattern is, to
a lesser extent, the result of photochemical reactions and nighttime scavenging combined
with daytime mixing of the concentrated high elevation air down into the valley.
Depressed summit concentrations near mid-day temporally coincide with peak diurnal
ozone at the valley site and suggest this mechanism. However, because year-to-year
trends in valley ozone concentrations do not follow summit trends, there may be a
significant influence of local emissions sources on valley ozone conditions. Thus, the
differences in ozone concentrations recorded at two sites are attributed to: 1) nighttime
stratification and formation of the PBL and attendant regional transport resulting in
higher concentrations above the PBL. 2) daytime breakup of the PBL by convectively-
driven mixing of summit and valley air, and 3) possible significant local sources for valley
ozone.
High and Low F.levation Aerosols
Daytime fine-mass aerosol concentrations from high and low-elevation sites
correlate well (Figure 3). The high elevation site, however, shows consistently lower
concentrations compared to the valley site. A correlation of fine mass PM between the
high elevation and low elevation sites for 1990-1992 data (Figure 3), exhibits a strong
correlation with a slope of unity (ANOVA rJ=0.83, p< 0005) and a 5 ug/m 5 (std error
0.827) intercept on the base site axis. Higher PMiS concentrations at the valley site may
be a result of emissions from local sources trapped below the PBL and by possible
localized mobile source input nearby the monitoring site. In 1993 the site was relocated
to reduce any influence of local source emissions. Because aerosol measurements are
made during the daytime, high and low elevation aerosols have been influenced by
mixing, based on the relationships in the ozone data. In 1994, further nighttime aerosol
measurements will aim at discerning Che PBL in the aerosol data.
CONCLUSIONS
In summary, we draw the following conclusions:
H Summit ozone data are strongly influenced by regional transport above the
PBL; peak ozone concentrations measured at night result from regional
transport and an approximate half-day time-lag from emissions sources
2) The valley site is isolated from the higher nighttime ozone concentrations resulting from
regional transport due to nocturnal atmospheric stratification. Mid-day peak o/one
concentrations in the valley result from: 1) the strong diurnal cycle associated with
convective mixing of air and katabatic winds from higher elevations, and 2) possible local
sources in New Hampshire: valley minima are the result of radiational cooling and
scavenging.
3) Daytime aerosol concentrations at high and low elevation sites correlate well and show
no apparent PBL influence Higher concentrations in the valley are attributed to mobile
emissions sources but may also be related to a valley haze inversion at night.
648
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¦1) This work demonstrates significant deterioration of air quality in (he two Class-1 areas.
Fxposure of hikers and plants to the pollutant ozone is generally greater above treeline.
ACKNOWI.F.DGRMRNTS
This work was partially funded by a WMNF Recreation Cost Share Agreement. The Mount
Washington Observatory provided monitoring support at the summit site. Gene Likens provided funding
through a grant from the Andrew Mellon Foundation. AMC interns Marion lloimlequin and Sarah
Whitney and Jim Liptack are acknowledged for collecting and processing of data. Dr. Petros Koutrakis
is acknowledged for support for the project at HSPH. Kenneth Kimball reviewed this manuscript.
RI987 /993; AMC Technical Report 94-1, 1994.
Hill, L.. Bruce and Allen, George A.. The Role of Aerosol Pollutants on Visihilitv Impairment
in the Great Gulf and Presidential!Dry River Wilderness Class I Airsheds, White Mountain
National Forest. Nil,: 1992 Summary Report; AMC Technical Report 93-2.
Koutrakis, et al.; F.valuation of an Annular Denuder/Filtcr Pack System to Collect Acidic
Aerosols and Gases, Environ. Sci. Tcchnol. 1988 22 1463 1468.
Marple et al., low Flow Rate Sharp Cut Impactors for Indoor Air Sampling; Design and
Calibration. J, Air Pollut, CpuM Ayw. 1987 32
Puxbaum, H., Gabler, K., Smid, S., and Glattes. F., A One-Year Record of Ozone Profiles in
an Alpine Valley (Zittertal'Tyrol, Austria, 600 2000 m a s.l ), Ainu Fnv, 1991 25a 1759
1765.
Samson, P.I., 1978; Nocturnal Ozone Maxima, Atm. Fnv.. 1978 12 951 -955.
Wunderli. S. and Gehrig, Surface Ozone in Rural. Urban and Alpine Regions of Switzerland;
Atmospheric Environment 1990 2M 2641-2646.
649
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650
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Lakes of the Clouds Site Fine Mass Aerosol (ug/m3)
60
Figure 3: Linear regression of paired nominal 10 hour daytime fine mass aerosol concentrations
from high elevation Lakes-of-tlie Clouds site and valley site 1990-1992 (ANOVA f=
0.83, n=75, p< .000.5; intercept=4.747 std. error 0.821) Indicates average higher
daytime fine mass concentrations in valley.
651
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Temporal and Spatial Characteristics of Particle Mass
in Metropolitan Philadelphia
G.A. Allen, P. Kuulrukis, and H.H. Suh
Harvard University
School of Public Health
665 Huntington Avenue
Boston, MA 02115
W.F.. Wilson and R.M. Burton
Atmospheric Research and Exposure Assessment laboratory
U.S. EPA
Research Triangle Park. NC
Particle inuss concentrations (PM- < and PM;0) were measured daily or every
other day at seven residcntially oriented sites in Philadelphia, PA during the summers
of 1992 and 1993. Samples were collected for 24-h periods using 10 Lmin"1 Harvard
Impactors for mass. Coarse mass concentrations (2.5 < da < 10 am) were determined
by subtraction ol" PM2.s frc,r» PMI0. To allow improved temporal characterization
during periods of elevated particle mass concentration, continuous or semi-continuous
methods for mass, sulfate, and black carbon were also used at one site for the first
summer.
Concentrations of PM,0 and l'V1;, were reasonably uniform across the urban
area, reflecting the regional nature of summertime transported secondary aerosols
typical of summer months in the northeast US. Temporal variation in 24 h
concentrations of PM2 S and coarse particle mass are compared and contrasted for a 12
week period at the two sites. I-'inc mass is shown to dominate the daily and short term
(6 to 12 h) temporal variation of PM10 concentrations. The relative contribution of
elemental carbon and sulfate to the total fine particle mass concentration is contrasted
for short term periods of high fine mass concentrations relative to similar periods of
nou-episodic concentrations, as well as for the 24 h duration samples.
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SESSION 15:
STAINLESS STEEL CANISTER
SAMPLING AND ANALYSIS
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Intentionally Blank Page
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SLMMA Canisters - Do They Need to Be Cleaned for TO-14 Analysis?
Ret A. Rasmussen
Oregon Graduate Institute
196(K) N.W. von Neumann Drive
Bcaverton, OK 97(K)6
Once properly cleaned, should Summa canisters undergo the riggers of cleaning
once again when used to collect ambient air samples? The importance ol' thorough and
proper cleaning of stainless steel canisters is known for the proper collection and
analysis of ambient air samples. The need for continual cleaning of each canister
before use for collection of ambient air samples when used previously for ambient air
will be discussed.
655
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BEYOND CANISTER CLEANING...WHAT ABOUT THE SURFACE
CHEMISTRY?
R.R. Freeman, C. C. Crume and E. D. Winegar
Air Toxics Ltd.
180 Blue Ravine Road, Suite B
Folsom, CA 95630-4719
There exists a need for a rapid, definitive test for measuring the surface activity of
a canister. The test must meet four criteria: (1) the test solution must be stable in and of
itself, (2) the test must be rapid (i.e., less than 10 minutes), (3) the test must be a simple
GC test and (4) the test must discriminate between "inert" and "active" surfaces.
Results will be presented using different test probes and a number of new
canisters, from two different manufacturers. Test probe recovery as a function of time
demonstrates the variability in the surface of the new canisters and also allows the
calculation of a statistically derived "inert" surface database. A variety of older canisters
were evaluated in order to demonstrate the utility of the test to identify inert and active
canister surfaces.
This chemical test provides the laboratories with an additional means of
demonstrating the inertness of a canister to prospective data users. It serves to add
validity to the data set.
INTRODUCTION'
TO-14 is one of the methods included in the Compendium of Methods for the
Determination of Toxic Organic Compounds in Ambient Air. The Compendium was first
circulated in 1984 and later updated in 1986 and 1988. Much has changed since 1988 and
the use of TO-14 for the analysis of volatile organic compounds (VOCs) has been
extended to include a more comprehensive list of target compounds and sample matrices
beyond ambient air. In addition, risk, assessment determinations have made it necessary to
measure many toxic compounds at the pptv level and TO-14 is often specified as the
method of choice.
Beyond the obvious difficulties associated with accurately detecting a compound
at the pptv level, there are a number of other factors which must be considered,
understood and managed before the data can be considered meaningful. The addition of
polar, (i.e., more reactive) compounds to the target compound list (TCL) necessitates that
the sampling equipment (sampling line, critical orifice particulate filter and canister) be
inert as well as clean. The fact that Summa canisters are often used for matrices other
than ambient air means that the canister surface is often exposed to corrosive compounds
such as hydrochloric acid, high levels of humidity and samples which may have a number
of non-volatile compounds (at room temperature and ambient pressure). The
accumulation of these non volatile compounds (which may or may not polymerize during
the normal canister cleaning process) will degrade the Sumina surface. It is fair to assume
that once a canister has been in service for over a year that the Summa surface has been
compromised, the degree of which is currently not monitored by most commercial
laboratories.
656
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Some laboratories recognize the dangers of using damaged canisters (i.e.,
canisters whose surface have been exposed to non-ambient sample matrices) for low level
ambient air determinations and segregate their canisters into "ambient' and 'other". This
approach is not only expensive but often impractical given the degree of sophistication
required of the canister tracking program and the fact that "ambient" is a relative term and
is often mis-applied to a given set of samples.
TO-14 specifies that the sample be collected and stored in a Summa canister prior
to analysis and it provides guidance on how to clean and certify canisters. However, there
is essentially nothing available on the chemical characterization of the canister surface.
Concerns about surface adsorption are addressed primarily by varying the humidity
within the canister prior to sampling and the temperature during analysis. Studies of
recovery versus humidity / temperature always fail to take into account the variability
found in real world samples. The conclusions of the studies are invariably valid only for
ambient air and fail to consider the effects of other sample matrices on the Summa
surface.
Canister cleaning protocols utilize exponential dilution, heat (often in the presence
of moisture and oxygen) and vacuum to remove VOCs and moisture from the canister. A:
the end of the process the canister is free of VOCs and very "dry". The two most common
methods of "certifying" canisters (TO-I4 and TO-12) simply measure the residual level
of volatiles remaining after the "cleaning" process. They answer the question: Are there
VOCs in the canister? They do not measure the inertness of die SUMMA surface. This
may be fatal short coming if the canister is used to acquire and store a sample for which
the TCL includes a number of polar compounds and pptv data is requested.
The recovery of reactive compounds in a complex matrix at the pptv level
requires a chemical characterization of the canister surface. While humidification of the
surface may mask" the chemical activity of the surface in the short term, its effects on
recovery over time are difficult to predict. This situation is analogous to that which exists
in the world of gas chromatography. The importance of measuring the residual chemical
activity of a gas chromatographic column has long been acknowledged by
chromatographcrs. All column manufacturers test each column with a "polarity mix" to
measure the chemical nature of the column surface. If a general purpose column like DB-
5 adsorbs (usually indicated by peak tailing, a decrease in peak height or, in severe cases,
peak abstraction) the phenol or the alcohol, it is rejected. Most laboratories monitor
column performance as a means of determining when the column has degraded to the
point where it must be replaced. This same approach can be applied to testing the surface
of a canister.
One. injects a "polarity mix" into a clean canister. If the surface is chemically
active, or if there is a residue on the surface, one or more of the active compounds in the
mix are adsorbed. The degree of adsorption serves to characterize the surface. Using this
approach canisters can be classified into two groups: "inert" and "active".
EXPERIMENTAL
In order to be practical the test must have the following characteristics: (1) it must
be a simple gas chromatographic test. That is, the sample is injected using a gas tight
syringe - no cyrotrapping. The column should separate on the basis of boiling point (DB-
1 or DB-5) in order to facilitate peak identification. A conventional flame ionization
detector is used because of its universal response and general availability. (2) the test
must be relatively quick, that is, less than 10 minutes and (3) the results must be easily
inteipreted. Canister classification is based on peak height relative to one of the iuert
(e.g., 2,2,4-Trimethylpentane or benzene) compounds. Because of the relative nature of
the measurement it is not necessary to calibrate the gas chromatograph.
One of the most difficult aspects of developing a text mix with a multiplicity of
functional groups is to find compounds which are both miscible and stable in solution.
Should the compounds react or decompose (a common problem with amines) the findings
-------
Figure 1 shows a typical chromatogram along with peak identification. The oven was
program from 40°C to 11CTC at 10°C/min. Column: 30m X 0.53, DB-5.
Three different studies are summarized below:
(1) Recovery as a function of humidity using new canisters.
(2) Recovery as a function of hold time. Obviously the goal is to develop a
test which provides sufficient information to classify a canister in the
least amount of time.
(3) A demonstration of the tests ability to classify canisters.
A large group of canisters have been evaluated including new canisters (from two
manufacturers), canisters which have been in use for 1-5 years and canisters which have
been exposed to hydrocarbon process streams containing high levels of sulfur
compounds. Glass surfaces were also investigated.
RESULTS AND DISCUSSION
New canisters were used to establish the "baseline1' statistics for a freshly
prepared Summa surface. Canisters from two manufacturers were used m order to
eliminate any bias due to manufacturing variations. No attempt was made to differentiate
canisters on the basis of vendor; however, there are significant differences between the
two groups of canisters and it is a simple manner to identify the manufacturer or. the basis
of the test. This study was run using both humidified and dry canisters. It is clear from
Table II that the common TO-14 analytes are well behaved and can be used as indicators
of a valid test, while the polar compounds are less predictable and, as expected, humidity
plays as strong albeit transitory role in recovery. The data in Table II is a summary of the
average relative response taken at 30 minutes, 60 minutes. 90 minutes and 18 hours after
injection mto the canister.
Table II. AVERAGE RESPONSE USING NEW CANISTERS (n=6)
TEST PROBF.
R- - DRY CANISTER
Rf - HUMIDIFIED
CANISTER
1-Propanol
1.4+0.19(14% RSD)
1.3+0.015 (5.0% RSD)
Chloroform
0.34+0.006 (2.0%)
0.34+0.005(1.5%)
Benzene
2.0±0.048 (2.3%)
1.910.056 (3.0%)
2.2,4 Trimethvlpentane
INTERNAL STD.
INTERNAL STD.
Methylisobutylketonc
1.2=0.13 (11%)
1.2±0.42 (3.3%)
Benzaldehyde
4.7+2.2 (46%)
4.1 + 1.3 (33%)
Phenol
2.7±1.2 (41%)
1.410.94 (65%)
The relative response for benzaldehdye and phenol is bi-modal. Both the
magnitude of the relative response and its associated standard deviation varies between
the two manufacturers. Canisters from a single manufacturer yield much better precision
than is indicated above for the combined canister set...
For comparison purposes a number of glass bulbs were evaluated in order to
compare the test performance on, what is normally considered to be a more inert surface
than "Surmna". The glass surface was not specially treated or silanized prior to testing.
Any benefit of such treatments have been demonstrated to be transitory in nature and
certainly not of any value as a surface treatment prior to taking an air sample. In fact,
inorganic acids (e.g., HC-1) and water readily attack a silanized surface. The subsequent
formation of silanes and cyclic-siloxanes will often complicate the VOC analysis.
While this study can hardly be considered definitive, results indicate that for
common (i.e., non-polar) TO-14 target compounds there is no difference between a
"Summa" surface and an untreated borosilicate surface (2.9% Rf difference for
658
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are of questionable value. For example, during the course of this study attempts were
made to use benzaldehdye and butyl amine as test probes. These two compounds react
invalidating the tesf results despite the fact that they appear to be ideal test probes. Such
problems require the mix to be made daily which adds a level of inconvenience and
threaxns the incorporation of the test into every day use.
The probes selected must be volatile; it is essentia' that the test probe have a
boiling point under 175°C otherwise there may be difficulty removing it from the canister
upon completion of the test. The ideal candidate is, first of all, not a common TO-14
targe: compound and, secondly, has a boiling point between 60 and 150°C.
Table I lists the molecular probes utilized during the course of this study; Figure 1
shows a typical chromatogram of this test mix. The test mix is made up in methanol a:
approximately SOmg/mL. 0.5 ml. was injected into the canister. 0.5ml . was injected into
the gas chromatograph which was, in turn, split approximately 100:1. As previously
mentioned, other probes were investigated but found to either be unstable in the mix or of
limited value. The compounds have a range of polarities in order to provide a range of
possible surface interactions. For example, the alcohol will easily hydrogen bond; the
acidic compound, phenol, provides a good measure of the acid/base nature of the surface.
The aldehyde is very reactive. These tliree compounds were selected because they are
reactive and often appear on TCI.s. The inert compounds serve as internal standards and
provide a demonstration of test validity. This mix, when stored in the freezer, is stable for
up to 8 weeks.
Table I. TEST PROBES FOR CANISTER SURFACE ACTIVITY
TF.ST PRORF.
ROILING POINT
DiPOLE MQMfcXT
1-Propanol
97CC
1.68
Chloroform
6l°C
i.o:
Benzene
80° C
0
2,2,4-Tnmethylpentane
98* C
0.18
Methylisobutvlketone
Benzaidehvde
118°C
NA
17S°C
2.7
Phenol
182°C
1.45
1
1.1-Propanol
2. Chloroform
3. Benzene
4. Isooctane
5. MIBK
6. Benzaldehydu
7. Phenol
'ULUUv_
o.oo
9.0i
Figure I shows a typical chromatogram along with peak identification. The oven was
program from 40°C to 110CC at I0°C/min. Column: 30m X 0.53, DB-5.
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chloroform and 0°!c Rf difference for benzene) with respect to recovery over time.
I iowever, the data clearly suggests that glass, with irs high population of surface silanols
adsorbs the polar, less volatile Analytes more than does a Summa surface (e.g., there is a
66% difference in Rf for both benzaidehdye and phenol). These relative response factors
were gathered over 2 hours. Move work needs to be done or. other "glass" surfaces using
a variety of surface deactivation techniques such as huinidification in conjunction with a
variety of matrices and analytes.
RECOVERY FROM DRY, USED CANISTERS
The used canisters were all characterized without humidity. The presence of
moisture in the canister very effectively masks the surface for most organic compounds in
the short term and makes the distinction between surfaces much more obscure. Two
canisters which had been exposed to hydrocarbon process streams containing a
significant amount of organic sulfur were also tested. The canister surfaces were, in fact,
black.
While the vast majority of canisters tested performed very much like the new
canisters, a few provided a clear demonstration of the. value of surface characterization.
Figure 2 shows three chronvatograms acquired from a single canister after a period of 90
minutes. It is clear from the changes in peak height, See Table HI, that the surface is quite
active. Virtually all of the methanol solvent is adsorbed. All of the polar compounds
show a decrease in recovery with time while the non-polar, TO-14 analytes such as
chloroform and benzene are unaffected. This canister is clearly not suitable for the
determination of polar analytes at low levels. It is interesting to note that in every ease
where surface activity was found, the recovery of the non-polar target compounds was
unaffected.
Table III. AVERAGE RESPONSE (n=6) FOR AN "ACTIVE" SUMMA CANISTER
IES_T_PROBE
Rf @ 20 MIN.
Rf @ 60 MIN,
R^@90MEL
1 -Propanol
1.3
0.34
0.30
Chloroform
0.34
0.34
0 34
Benzene
2.0
2.0
2.0
Isooctane
INTERNAL STD.
INTERNAL STD.
INTERNAL STD.
MIBK
1.3
0.93
0.91
Benzaldehyde
6.9
2.0
0 86
Phenol
3.2
1.7
0.82
RECOVERY USING HUMIDIFIED CANISTERS
It has been well documented that the recovery of polar compounds is enhanced if
the canister is humidified prior to sampling. The question must be asked, will a layer of
water render an active canister surface inert? Two of the canisters which had been
classified as "active" were cleaned, humidified and re-tested. The results for one such re-
test is presented in Figure 3. Note that the recovery of the non-polar TO-14 target
compounds is unaffected by humidity; however, the recovery of the polar compounds is
greater from the humidified canister although recovery decreases over time. This work,
en mass, clearly supports the body of work that shows that polar compounds are best
recovered from a humidified canister rather than a dry canister. This work also suggests
that recovery is more dependent on humidity than the residual chemical activity of the
surface. More works needs to be done in order to determine the duration of the enhanced
recovery on a humidified surface. For example, what is the hold time of a sample
containing polar analytes on a Sunima, or for that matter, any surface?
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RECOVERY AS A FUNCTION OF HOLD TIME.
It is important to determine the length of ume necessary to differentiate the
canister surfaces. In this study the canisters were analyzed at 30 minutes, 60 minutes, 90
ir.inutes and 120 minutes. Several tests were performed after 18 hours, but 18 hours falls
outside the realm of being a practical test. The data changed very little between 60 and
120 minutes. The 30 minute data is suspect because the relative response for the polar
compounds was often lower than that obtained after 60 minutes. The mixing in the
canister takes a finite time that increases with decreasing compound volatility. A
meaningful surface test requires at least a 1 hour hold time prior to analysis. Because the
analysis only takes 8 minutes, 6 to 8 canisters can be evaluated/hour.
SUMMARY
Canisters should be differentiated on the basis of the TCL and not the source of
the sample. Regardless of the nature of the surface it appears that non-polar TO-14
compounds can be recovered at levels approaching 100%. In addition, the recovery is
constant over time (at least up to 14 days). The recovery of polar compounds mandates
that the surface be humidified; however, the increased recovery appears to be transitory
and is clearly a function of the surface chemistiy.
Chemical characterization of the canister surface can be accomplished in a little
more than 1 hour. It provides the laboratory with a basis for quantitatively grouping
canisters into active and inert. This test provides an additional level of QA to the
laboratory and helps ensure data quality when polar compounds are of interest.
The value of periodically characterizing the surface of each canister in use has
been demonstrated. In our laboratory each canister is evaluated after 5-6 cycles to the
field except for those instances where high level of organics or sulfur compounds have
been found. In these instances each canister from the project is subjected to a test and a
judgment made with regards to its utility in the future. It also helps to find those canisters
which contain non-volatile material.
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HOLD TIME 30 M1N.
4CCOO-
4000C-
HOLD TIME 60 MIN.
u
HOLD TIME 90 MIN.
UU
e. -4-
o.o
8.3
Figure 2. Three chromatogranis from an "active" canister. See Figure 1 for peak
identification
662
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Benzaldehyde
Benzaldehyde
H = HUMIDIFIED
D = DRY
A ^"*1
Phenol
Phenol
Benzene
Benzene D'
30 60 90
HOLD TIME (min)
Figure 3. Relative Response for three test compounds (Benzene, Benzaldehyde and
Phenol) using an "active" canister. The canister was tested both dry and humidified.
663
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DEVELOPMENT AND VALIDATION OF A HEATED
CANISTER-BASED SOURCE SAMPLING METHOD
Robert J. Crawford
NCASI
P. O. Box 141020
Gainesville, Florida 32614-1020
David L. Elam
Roy F. Weston, Inc.
1635 Pumphrey Avenue
Auburn, Alabama 36830-4303
ABSTRACT
In response to the Clean Air Act Amendments of 1990, the United States pulp and paper
industry through the American Forest and Paper Association (AF&PA) has instituted a program to
characterize hazardous air pollutant (HAP) emissions from a variety of sources at 16 facilities. To
meet some of the specific needs of this program, a method has been developed, based on EPA
Method 18, that uses a heated sampling system to transfer source gas samples to a heated stainless
steel summa polished canister. After sampling, the canister is kept hot in an insulated box and
transferred to an on-site mobile laboratory'- All of the analyte system components arc also heated so
that the moisture is not allowed to condense in the sample before it is analyzed. An initial mill
screening study, laboratory evaluation;'validation, and an EPA Method 301 validation on pulp mil)
sources have all been completed with acceptable results. This method is being used to quantitate 26
VOCs, e.g., methanol, acetone, methylene chloride, chloroform, benzene, methyl ethyl ketone, and
methyl isobutyl ketone.
BACKGROUND
The heated canister-bascd source sampling method described in this paper was developed to
meet the specific needs of the American Forest and Paper Association Maximum Achievable Control
Teclinology Study (AF&PA MACT Study), This study was organized by the AF&PA and NCASI
to meet the information needs of the pulp and paper industry relative to the implementation of the
1990 Clean Air Act Amendments (1).
The project is managed by NCASI. Roy F. Weston, Inc., Auburn, Alabama was contracted
to perform the testing. In tliis study speciated VOC emissions, primarily HAPs, were measured at
16 facilities over a 14'A month period. Approximately 20 sources were tested at each facility. The
analyte list included 26 compounds.
A method was needed that could quantitate individual VOC emissions to ^0.1 lb/hr emission
rates. This corresponds to an approximate quantitation limit of = <0.1 ppmv. We also desired to
quantitate lower emissions when possible. Definitive qualitative analysis and the ability to identify
any major VOCs not on the calibration list were required. Fast data turn around, within 24 hours,
was a requirement. This meant that on-site analysis in a mobile laboratory was required. Fast data
turn around was required to allow us to make decisions in the field about: which samples to run on
the GC-MS, additional tests on sources which yielded questionable results, and deletion of tests on
sources found to have insignificant emissions. Ail additional requirement of the method was
sampling train mobility. In the initial plaiuiing for the project, the determination of source
variability by intermittent sampling over a multi-day period was envisioned. Thus, the sampling
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train* would need the mobility to be rotated from source to source around the mill. The method
chosen for this study was required to collect an integrated sample. Finally, we needed a method
that was validated by EPA Method 301 (2). Unfortunately, no methods were validated for VOC
HAP measurements in pulp and paper mill sources. Thus, we would have to validate the method
we chose for this project.
The sources to be tested in this study included pulping, bleaching, and combustion sources at
kraft, sulfite, and semi-clieinieal pulp and paper mills. These sources are often high temperature,
high moisture, and contain corrosive gases, e.g., SO;, Cl;, CIO.. NO,.
The target analytes for this study are listed below.
TARGET ANALYTE LIST
methanol
chloroform
benzene
acetone
dichloromethane
toluene
methyl ethyl ketone (MEK)
1,2,-dichloroethane
xylenes
acetaldehyde
1,2-dichloroethylene
styrene
methyl isobuty! ketone
(MIBK)
1,1,1-trichloroethane
terpenes
acrolein
1,1,2-trichloroethanc
methyl mercaptan
formaldehyde
1,2,4-trichIorobenzene
dimethyl sulfide
total hydrocarbons (THC)
tetrachloroethylene
dimethyl disulfide
carbon tetrachloride
trichloroethylene
chlorobenzcne
hcxane
We could not find an existing developed method to meet our desired method's
characteristics, therefore we decided to develop a new method that best fit the specific needs of this
project.
METHOD DESCRIPTION
We decided that a canister-based method would be ideal for the needs of this study except for
he problem that the condensed moisture would cause when the source gases cooled to ambient
emperature. Thus, we decided to try an approach in which we kept the canister hot so that the
noisture is not allowed to condense. Additionally, the sampling and analytical system components
ire kept hot so that moisture is never allowed to condense in the sample. This method is really a
'ariation of the heated sample line option of EPA Method 18 (3).
Figure 1 diagrams the sampling system. The sampling system consists of four major
omponents: probe, filter box, flow control module, and canister module, all of which are heated to
SOX. At the conclusion of the test period, the canister module is removed from the sampling
ystem and transported to the mobile laboratory where it is maintained at 130°C pending analysis.
Canister vacuum draws the sample. The canisters are constructed of summa polished stainless steel.
Canister volume is six liters; metal bellows valves are used for closure. Typically, samples are
665
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collected at a 50-70 ml ./mm flow rate for 1 hour. Mow control is via a micrometer-type needle
valve and vacuum gauge.
The following text describes sample collection procedures.
Once an acceptably clean canister is obtained, it is evacuated and heated to 130°C. The
pressure in and temperature of the canister are measured with an electronic manometer and digital
pyrometer, respectively. These data are recorded for sample volume calculation purposes. The
sun una canister is connected to the flow control module, and the sampling train is positioned at the
sample location. Ml components are then heated to the sampling temperature of 130°C.
Once all components have reached the required temperature, a leak check is performed on
the HSCSST by attaching a pressurized canister to the probe tip and pressurizing the system to
approximately five pounds per square inch (psi). During the leak check procedure, the valve on the
pressurized canister is opened until the pressure in the sample train reaches 5 psi. After the desired
pressure is obtained, the valve on the pressurized canister is closed. The valve on the evacuated
canister that is used for sample collection remains closed during all leak check procedures. A leak
rate of less than one percent of the sampling rate was considered acceptable.
After an acceptable leak check has been obtained, the HSCSST is ready for operation.
Immediately before sampling begins, the HSCSST is purged by attaching a vacuum pump to the
purge port. The system is purged with source gas at a flow rate of 200 mL/inin for a period of
three minutes. When the purging operation is complete, the three-way purge port valve is rotated to
complete the sampling circuit and close the purge circuit.
Sampling is initiated by opening the bellows valve on the heated summa canister. A needle
valve is used to adjust the sampling rate during the sample period. The canister vacuum gauge and
train component temperature values are recorded by the sampling train operator at the beginning and
end of the sampling period and at five minute intervals during the sampling period.
At the completion of each sampling run. the bellows valve on the heated canister is closed.
A post-test leak check is performed in the same manner the pre-test leak check was performed. The
run is considered acceptable if the post-test leak check is acceptable.
After the leak check is completed, the summa canister is disconnected from the HSCSST and
immediately transferred to the on-site transportable laboratory. Canisters are transported such that
the canister temperature does not drop below 100°C. Once at the laboratory, the summa canister is
maintained at 13Q°C pending analysis.
The analytical system, schematically depicted in Figure 2, consists of the equipment
necessary to interface the summa canister to both a cryogenic sample concentrator and a rotary
sample valve. The cryogenically concentrated sample can be delivered to both a GC/FID and an
optional GC/MSD. Additionally, a whole gas sample can be delivered to the other channel of the
GC/FID.
The analytical system employs two separate OCs. One GC is equipped with dual FIDs. Th(
other GC is equipped with the optional MSD. Table 1 summarizes the operating criteria for the gas
chromatograph systems.
Each channel of the GC/dual FID is fitted with several megabore capillary columns
connected in series. One channel is plumbed to a rotary sample valve for introduction of whole gai
666
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samples. The other channel is plumbed to one of the two outlets from the cryogenic concentrator
for introduction of cryoeenically concentrated samples. The use of two columns and two different
sample application techniques significantly extends the analytical range of the system as compared to
the use of a single sample application system. This chromatographic system is calibrated to yield
quantitative data.
For the purposes of this study, the concentrator quantitation limit was chosen to be equal to
the level of the lowest calibration standard. The system is capable of quantising lower
concentrations than the quantitation limits used in this study. The heated valve quantitation limits
were determined by the analyst's judgement of the smallest chromatographic peak area that would
yield reasonable quantitation limits in pulp and paper mill sample matrices. The concentrator and
heated valve pptnvd quantitation limits are listed in Tabic 2. These values assume canister dilution
factors of one and two for the concentrator and heated valve systems, respectively.
METHOD EVALUATION/VALIDATION
The heated canister method evaluation/validation was a three step process which included a
field feasibility study, a laboratory evaluation, and an EPA Method 301 validation exercise.
Figure 3 diagrams the sampling apparatus used in the field feasibility study. The sample was
drawn through a heated probe, filter box. and through a heated transfer line into a heated box.
Inside the heated box the sample line is connected to a manifold. Four sets of flow control
apparatus were connected to the manifold. A set of flow control apparatus consisted of a high
temperature variable area flow meter, a fine metering valve, and a vacuum gauge. Heated transfer
lines connected the outlets of the flow control apparatus to the six liter canisters contained in heated
boxes.
At the conclusion of each feasibility study sampling period, two of the four canisters were
spiked with a mixture containing the 20 compounds listed below.
FEASIBILITY STUDY SPIKE COMPOUNDS
methanol
toluene
ethanol
ethyl benzene
acetone
m/p-xylene
isopropyl alcohol
o-xylene
dimethyl sulfide
cumene
methyl ethyl ketone
a-pinenc
chloroform
ci-pinene
benzene
3-earene
bromodichloromethane
p-cymcnc
dimethyl disulfide
Feasibility study results obtained from sampling a brownstock washer filtrate tank vent, a
each plant scrubber outlet, and a kraft recovery furnace are contained in Tables 3, 4, and 5,
speetivelv. In the interest of conserving space, only the results for methanol, acetone, MEK,
667
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chloroform, and benzene are shown in these tables. Precision was calculated as the percent
difference (see equation below) between the two spiked samples.
percent difference = ( fsanfe 1 - samPle 21 ) x 100
(sample 1 + sample 2)12 \
Spike recover}' was calculated from the average of the spiked and unspiked canister results,
as shown in the equation below.
,ava. spiked conc. - ave. unspiked conc.s
percent recovery ~ (—b— —¦" * ) x 100
spike conc. (2.
Storage stability was calculated from the difference in initial and subsequent analyses, as
shown in the equation below.
storage stability, percent = - initial cpn^ x m
initial conc. ' (3
The results from the feasibility study were promising so we proceeded with a laboratory
method evaluation. The laboratory evaluation included the analysis of a synthetic stack gas with 30
percent moisture at 130°C. The synthetic stack gas was simultaneously sampled with four trains.
This was repeated four times. Hie synthetic stack gas analytes are listed below.
SYNTHETIC STACK GAS ANALYTES
methanol
benzene
acetone
MIBK
methylene chloride
toluene
methyl ethyl ketone
a-pinene
chloroform
0-pinene
The range of synthetic stack gas theoretical analyte concentrations and the percent recoveries are
listed in Table 6.
With the exception of a- and 0-pinene, which seem to react on the heated canister surfaces
the results of the laboratory evaluation were acceptable, thus we proceeded with the EPA Method
301 validation of the heated canister method on pulp and paper mill sources.
The EPA Method 301 validation procedure for an individual source requires that six runs t
conducted with four simultaneously operated sample trains with collocated probes. Two of the
canisters from each quadruplicate run are spiked at the conclusion of the run. Bias and precision
are statistically calculated from the results of the six quadruplicate runs. For a method to be
acceptable, the bias correction factor must be between 0.7 and 1.3, and the precision (relative
standard deviation) must be within ±50 percent. The Method 301 validation was conducted on tl
five following sources: brownstock washer hood, bleach plant scrubber inlet, smelt dissolving tai
recovery furnace, and lime kiln. Eight compounds, which were considered to have the highest
potential for release from pulp and paper mill sources and which were considered to be
66K
-------
representative of the types of other compounds released in traec amounts, were chosen as the target
compounds for the Method 301 validation. 'the results obtained from the EPA Method 301
validation are contained in Tables 7 through 11. All of the results for the bleach plant scrubber inlet
(Table 7), brownstock washer vent (Table 8), and the smelt dissolving tank vent (Table 9) are in the
acceptable range. All of the results for the lime kiln (Table 10) and recovery furnace (Table 11) are
acceptable except for the bias correction factors for benzene from both sources and the bias
correction factors for toluene and MEK from the lime kiln. The uncertainty associated with
measurement of the very low concentrations of benzene and toluene in both the spiked and unspiked
samples probably caused the error which resulted in the apparent high recoveries from the sources.
The low recovery of MEK from the lime kiln (correction factor 1.38) was likely due to canister
degradation.
DISCUSSION
It is important to caution the potential user of this method about some of the major problems
that will be encountered when using this method. Degradation of sampling train, canister, and
analytical system surfaces is a constant problem. In the early stages of surface degradation, MEK,
MIBK, and 1,1.1-trichloroethane recoveries are reduced. As the degradation becomes more severe,
the recovery of other compounds may be affected. New canisters need to be screened before use;
we have found about one out of four new canisters has active surfaces.
In the AF&PA MAC!" study, we have sampled approximately 320 sources at 16 facilities.
Typically, four test runs were conducted on each source with calibration for 26 compounds.
Relative to the specific needs of this study, we have generally been satisfied with the method
lerformance. As of the date of this writing, we have not thought of a method or combination of
nethods that would have better allowed us to accomplish the goals of this study.
There is still much potential for further research relative to the development, improvement,
,nd extension of this method. The sampling, storage, and transfer temperature of I30"C was
hosen on the basis of scientific judgement. The project time frame did not allow for determination
if an optimum temperanire; rather, I30"C was chosen because it was thought by the people
ivolved to be a temperanire that would allow the goals of the project to be accomplished. The
lethod could be extended to other compounds. An area of potential research that would be very
seful is the potential evaluation and development of hot sampling, cold canister storage, and hot
nalysis. If the canisters could be stored at ambient temperature between sampling and analysis, it
ould allow the test team to ship the canisters to a remote laboratory for analysis which would
gnificantly decrease the cost of doing this type of testing. Finally, research into techniques for
tssivating degraded sampling system, canister, and analytical system surfaces would be very
seful.
(TERATURE REFERENCES
Clean Air Act Amendments of 1990, ' Title III - Hazardous Air Pollutants," November 15,
•90. Public Law 101-549.
Appendix A to Pan 63 - Test Methods, Method 301 - "Field Validation of Pollutant
;asurement Methods from Various Waste Media," Federal Register, December 29, 1992, 57,
0, 61998.
"Kl'A Method IS - Measurement of Gaseous Organic Compound Emissions by Gas
romatography," Code of Federal Regulations, Pan 60, Appendix A.
669
-------
TABLE 1 TYPICAL OPERATING CRITERIA FOR THE
GAS CHROMATOGRAPH SYSTEMS
GAS CHROMATOGRAPH/DUAL FLAME IONIZATION DETECTORS
Column
0.53 mm ID x 30 m SPB 1 (5 /tm film) followed by
0.53 mm ID x 30 m SPB 5 (5 fim film) followed by
0.53 mm ID x 2 m CARBO WAX (1.2 film)
Carrier
Ultra high purity helium, regulated via electronic
pressure control (EPC). 10 mL/min.
Hydrogen
30 mL/min
Air
300 mL/min
Injector Temperature
175°C
Detector Temperature
250°C
Temperature Program
40°C for 5 minutes; ramp to 250°C at 8°C/minute;
hold at 250°C for 5 minutes
GAS CHROMATOGRAPH/MASS SELECTIVE DETECTOR
Column
0.2 mm ID x 30 m SPB I (0.8 jim film) followed by
0.2 mm ID x 30 m (SPB 5 (0.8 fxm film)
Carrier
Ultra high purity helium, regulated via electronic
pressure control. 1.0 mL/min.
Temperature Program
40°C for 5 minutes; ramp to 250°C at 8°C/minute;
hold at 250°C for 5 minutes
Detector Vacuum
4.5 x 10"3 Torr
Mass Range Scan
28 AMU 250 AMU
CRYOGENIC PRECONCENTRATOR
Sample Drying
None
Sample Volume for Calibration
100 mL
Cryotrap Temperature
-120°C
Cryofocus Temperature
-120"C
Desorb Temperature
150°C
System Bakeout
150°C for 5 minutes
670
-------
TABLE 2 HEATED CANISTER METHOD QUANTITATION LIMITS
USED IN THE AF&PA MACT STUDY
1
QUANTITATION LIMIT, ppmv
1 ANALYTE
f
Heated Valve
Concentrator
acetaldehyde
-0.14
-0.04
methanol
-1.64
-0.12
methyl mercaptan
-1.00
-0.50
acetone
-0.10
-0.03
dimethyl sulfide
-1.00
-0.50
methylene chloride
-0.36
-0.09
1,2-dichloroethylene
-0.16
-0.03
methyl ethyl ketone
-0.14
-0.04
n-hexane
-0.10
-0.01
chloroform
-0.40
-0.12
1,2-dicliIoroethane
-0.14
-0.04
1,1,1-trichloroethane
-0.10
-0.03
benzene
-0.12
-0.01 j
carbon tetrachloride
-0.24
-0.12 1
trichloroethylene
-0.12
-0.03 1
methyl isobutyl ketone
-0.10
-0.01 I
dimethyl disulfide
-1.00
-0.50 I
1,1,2-trichJorocthanc
-0.10
-0.03 j
toluene
-0.08
-0.01 J
tetrachloroethykne
-0.66
-0,03 j
chlorobenzene
-0.12
-0.01 J
rn,p-xylene
-0.14
-0.01
o-xylenc
-0.14
-0.01 j
styrene
-0.08
-0.01 I
lerpenes
-0.01 |
1,2,4-trichloroben7ene
-0.02
-0.01
acrolein
0.10
-0.03 I
-------
TABLE 3 FEASIBILITY STUDY RESULTS - BSW FILTRATE TANK VENT
AVERAGE CANISTER, pprov
PERCENT
SELECTED
COMPOUNDS
Unspiked
Spiked
Precision
Recovery
1 Day Storage
Stability
6 Day Storage
Stability
methanol
340
1136
6
97
(-9
-2
acetone
2.3
131
5
103
+30
+30
MEK
0.45
115
9
102
+22
+24
chloroform
0
225
5
108
+3
0
benzene
0.14
73
1
106
+8
+ 7
-------
TAIilR 4 FEASIBILITY STUDY RESUI_,TS_-J3LEAOTJ>Ij\NT_SCRUBB_ER.OUTLET
AVERAGE CANISTER, ppmv
PHRCKNT
SHI.HCTED
COMPOUNDS
I Jnspiked
Spiked
Precision
Recovery
1 Day Storage
Stability
methanol
36
42
4
104
0
acetone
0.59
4.8
15
115
8
MEK
0
4.2
13
85
-4
cliloroform
22
8.3
0
114
+ 1
benzene
0.15
3.0
1
107
5
-------
TABI.lv 5 FI-ASimiJTY STUDY RHSUl.TS - RKCQVHRY HJRNACIi
AVERAGE CANISTER, ppmv
PERCENT
SF.l.KCTKD
COMPOUNDS
Unspiked
Spiked
Precision
Recovery
1 Day Storage
Stability
methanol
6.9
46
15
90
-11
acetone
0
5.3
1
94
+ 14
MF.K
0
4.6
11
58
+52
chloroform
0
9.0
26
95
-3
benzene
0.40
2.9
NA
118
-11
-------
TABLE 6 RESULTS OF SYNTHETIC STACK GAS ANALYSIS
ANALYTE
RANGE OF THEORETICAL
CONCENTRATIONS, pprav
AVERAGE RECOVERY,
PERCENT
methanol
6 - 13
117
acetone
1 - 2
108
methylene chloride
2 - 3
85
methyl ethyl ketone
0 7 - 1.3
88
chloroform
2 - 4
88
benzene
0.9 - 1.7
88
MIBK
1 - 2
86
toluene
0.5 - 1.2
87
u-pinene
1.3 - 1.5
61
jS-pinunc
0.9 - 1.4
39
675
-------
XABLK7 SUMMARY OF EPA METHOD 301 VALIDATION RESULTS. BLEACH PLANT SCRUBBER INLET*
SOURCE
STATISTICAL PARAMETERS
Compound
RSDs
RSDu
CF
SPIKE
CONCENTRATION,
ppm
AVERAGE EMISSION
CONCENTRATION,
ppm
methanol
2
11
1.07h
172.63
56.22
acetone
10
31
NR
40.43
0.53
methylene chloride
2
2
1.12"
64.35
0.78
methyl ethyl ketone
2
2
1.13**
24.50
0.30
chloroform
2
10
1.14b
74.11
11.35
benzene
3
2
1.16"
31.62
0.26
methyl isobutyl ketone
6
2
1.13k
31.78
0.22
toluene
6
2
1.02
18.69
0.17
RSDs = Relative Standard Deviation of Spiked Samples, %
RSDu = Relative Standard Deviation of Unspiked Sample, %
CF = Correction Factor
NR = Non-Required
"Heated Valve Used for Sample Application
Significant Bias
^Unacceptable
-------
TABLE 8 SUMMARY OF EPA METHOD 301 VALIDATION RESULTS. BROWNSTOCK WASHER VENT-'
SOURC1-
STATISTICAI. PARAMETERS
Compound
RSDs
RSDu
CF
SPIKE
CONCENTRATION,
ppin
AVERAGE EMISSION
CONCENTRATION,
ppm
methanol
8
3
1.06
486.30
387.16
acetone
4
16
0.96b
113.90
8.34
methylene chloride
6
12
0.95b
181.28
0.69
methyl ethyl ketone
8
6
0.94"
69.03
0.60
chloroform
4
12
NR
208.78
0.76
benzene
6
12
0.98
89.07
0.23
methyl isobutyl ketone
16
12
0.88b
89.51
0.19
toluene
19
14
OJP
52.65
0.15
RSDs = Relative Standard Deviation of Spiked Samples, %
RSDu = Relative Standard Deviation of Unspikcd Sample, %
OF = Correction Factor
NR = Non-Required
"Heated Valve Used for Sample Application
¦"Significant Bias
'Unacceptable
-------
TABLE 9 SUMMARYJ^FJ,R\ METHOn_30LV^UDAJION RESULTS^SMDUjlDISSX>LYIN G J"AN K_V EN E!
SOURCK
STATISTICAL PARAMETERS
Compound
RSDs
RSDu
CF
SPIKE
CONCENTRATION,
ppm
AVERAGE EMISSION
CONCENTRATION,
ppm
methanol
12
6
1.17b
123.84
63.49
acetone
8
6
0.94"
28.09
1.21
methylene chloride
S
5
NR
92.16
0.72
methyl ethyl ketone
11
5
0.87b
36.08
0.28
chloroform
9
5
NR
119.80
0.80
benzene
10
5
NR
9.98
0.24
methyl isobutyl ketone
13
5
0.90"
12.46
0.20
toluene
11
5
NR
8.39
0.16
RSDs = Relative Standard Deviation of Spiked Samples, %
RSDu = Relative Standard Deviation of Unspiked Sample, %
CF = Correction Factor
NR = Non-Required
"Heated Valve Used for Sample Application
'Significant Bias
'Unacceptable
-------
TABLE 10 SUMMARY OF EPA METHOD 301 VALIDATION RESULTS. LIME KILN'
SOURCE
STATISTICAL PARAMETERS
Compound
RSDs
RSDu
CI-
SPIKE
CONCENTRATION,
ppm
AVERAGE EMISSION
CONCENTRATION,
ppm
methanol
20
20
NR
4.64
1.00
acetone
26
35
NR
1.21
0.21
methylene chloride
23
12
0.81"
2.65
0.39
methyl ethyl ketone
37
12
00
r—
1.40
0.17
chloroform
26
12
0.72"
4.22
0.51
benzene
21
14
0.48^
0.45
0.04
methyl isobutyl ketone
30
12
0.79h
0.57
0.04
toluene
22
12
0.54"'
0.38
0.04
RSDs -- Relative Standard Deviation of Spiked Samples, %
RSDu - Relative Standard Deviation of Unspiked Sample, %
CF = Correction Factor
NR = Non-Required
"Entech Concentrator Used for Sample Application
•"Significant Bias
Unacceptable
-------
TABLE 11 SUMMARY OF EPA METHOD 301 VALIDATION RESULTS. RECOVERY FURNACE*
SOURCE
STATISTICAL PARAMETERS
Compound
RSDs
RSDu
CF
Sl'IKE
CONCENTRATION,
ppm
AVERAGE EMISSION
CONCENTRATION,
ppm
methanol
28
33
NR
38.07
5.89
acetone
18
27
0.82"
9.92
0.19
methylene chloride
23
12
NR
21.70
0.36
methyl ethyl ketone
49
25
NR
11.45
0.16
chloroform
19
12
0.78"
34.52
0.48
benzene
9
12
0.46ic
3.70
0.04
methyl isobutyl ketone
47
12
NR
4.64
0.04
toluene
16
12
0.72b
3.12
0.04
RSDs = Relative Standard Deviation of Spiked Samples, %
RSDu = Relative Standard Deviation of IJnspiked Sample, %
CF — Correction Factor
NR = Non-Required
'Entech Concentrator Used for Sample Application
bSignificant Bias
'Unacceptable
-------
- STAINLESS STEEL
FILTER HOLOER WITH
TEFLON FILTER
STACK
WALL
IX
J5L
o o
NEEDLE
VALVE
TEMPERATURE DISPLAY-
& CONTROL
VACUUM GAUGE-
PURGE
LINE
@ VALVE
X THERMOCOUPLE
PI HEATER
FIGURE 1 HEATED SUMMA CANISTER SOURCE SAMPLING TRAIN (HSCSST)
-------
ENTECH
CNTTCH Q o
CONTROL
CONSOLE
00
m
HEATED
SUMMA CANISTER
SAMPLE
CONCENTRATOR
litis
GAS CHROMATOGRAPH/MASS
SELECTIVE OETECTOR
HP CHEM STATION
WITH NIST MS LIBRARY
HEATED 10 PORT
ROTARY VALVE
I—1 1
• •
~* :
¦¦¦¦¦a
•
S §131
MP i.890
1
GAS CHROMATOGRAPH/DUAL
FLAME IONIZATION DETECTOR
PE/NELSON TURBOCHROME
DATA ACQUISITION SYSTEM
FIGURE 2 SCHEMATIC OF HEATED SUMMA CANISTER ANALYTICAL SYSTEM
-------
HEATED
CANISTER
BOX
CANISTER
HEATED
TRANSFER
LINE TO
CANISTER
NEEDLE VALVE -
VACUUM GAUGE
HEATED BOX
VARIABLE
AREA
FLOWMETER
PURGE
VALVE
SOURCE
HEATED
FILTER
BOX
HEATED
PROBE
FILTER
FIGURE 3 FEASIBILITY STUDY SAMPLING APPARATUS
-------
Recovery of Oxygenated Organics from SUMMA Canisters
Rci A Rusniussen
Oregon Graduate Institute
1961)0 N.W. von Neumann Drive
Bcavcrlon, OH 9700ft
It is well known that the atmospheric reaction products of many anthropogenic
and biogenic hydrocarbons are oxygenated organics. Many analytical techniques have
been used to monitor and determine ambient air concentrations ot these species with
limited success. Collection of oxygenated organics and recovery in various sampling
rcsigncs have been used but because of the sticky nature of these compounds to adlieic
to surfaces, analytical results have been questioned. The use of Summa canisters to
collect oxygenated organics and their recovery lor analysis will be discussed.
684
-------
Analysis of Selected Polar Volatile Organic Compounds
via TO-14 and Modified TO-14 Method
II. Wang
FiNSR Consulting and Engineering
33 Industrial Way
Wilminglin, MA 01887
SUMMA canister based sampling and analytical system (TO-14 method) has
gained wide acceptance for the collection and analysis of integrated whole ambient
air samples containing volatile organic compounds (VOCs). This method has been
very well developed for most non-polar volatile halogenatcd hydrocarbons and
hydrocarbons.
The studies are concentrated on suitability of TO-14 method for several polar
VOCs, including ketones, ethers, sulfur contained compounds, etc. Studies on alternate
technical approach and method modification arc also conducted. The results on
humidity effect, interaction between parameters, time dependent stabilities, and
comparison of different modifications are presented.
685
-------
Why Is It So Difficult to Measure Terpenes in Ambient Air?
Rei A. Rasmussen
Oregon Graduate Institute
19600 N.W. von Neumann Drive
Bcaverlon. OK 97006
Biogenic compounds and in general Terpenes make up a large fraction of the
volatile organic compounds emitted into the ambient atmosphere. The measurement of
Terpenes is of importance in knowing the biogenic contribution to the atmospheric
loading of organic compounds. The ambient concentrations of Terpcncs are usually
low in the ambient atmosphere which may in itself result in difficulties in their
analysis. The chemical and physical nature of the Terpenes many also lead to
difficulties in their analysis. Ambient air samples collected in Summa canisters under
conditions in which Terpenes should be present, and results of experiments
with Terpenes in Summa canisters will be discussed.
686
-------
Certification of VOC Canister Samplers
for Use at the Waste Isolation Pilot Plant
Linda Frank-Supka and Chuan-Fu Wu
Westinghouse Electric Corporation
Waste Isolation Division
P.O. Box 2078
Carlsbad, New Mexico, 88220
Gregory C. Meiners and Anthony S. Wisbilh
IT Corporation
11499 Chester Road
Cincinnati, Ohio, 45246
Robert A. Zimmer
Harding Lawson Associates
2400 AKCO Tower, 707 Seventeenth Street
Denver, Colorado, 80202
ABSTRACT
The Waste Isolation Pilot Plant (WIPP) site is designed to demonstrate safe disposal of trans-
uranic (TRU) mixed waste. An air monitoring program has been established at the WIPP site to
verify that volatile organic compounds (VOCs) do not migrate out of the disposal unit. In this air
monitoring program, modified commercially available dual canister samplers are used to collect air
samples for VOC analysis. Sampler certification, sample collection, and sample analysis are per-
formed based on the procedures contained in U.S. I-nvironmcntal Protection Agency's Compendium
Method TO-14. The canister samplers are certified for cleanliness hy passing humid zero air
through the entire sampling system and collecting a sample in a canister over a 24-hour period. In
addition, each canister sampler is certified for target compound recovery efficiency by passing a
humid calibration gas standard through the entire sampling system and collecting a sample in a
canister over a 24-hour period.
In this paper, we discuss the techniques developed for meeting the stringent certification require-
ments of the monitoring program and present data to support the need for these stringent require-
ments.
INTRODUCTION
The effort to locate a permanent disposal site for TKIJ waste began over 30 years ago when the
National Academy of Sciences recommended that radioactive waste be permanently disposed of in
alt beds. After a decade of review of potential sites by the Atomic Energy Commission, the Oak
(idge National Laboratory, and the U.S. Geological Survey (USGS), the WIPP site was selected.
The WIPP repository, an underground mine, is located approximately 2.150 feet below the sur-
ace in the Salado Rock-Salt Formation southeast of Carlsbad, New Mexico. The Salado formation
i a 2,000-foot-thick salt bed that extends laterally for approximately 36,000 square miles. The land
i the vicinity of the WIPP is owned by the Federal Government and administered by the Bureau of
.and Management. The 4-mile by 4-mile plot of land overlying the repository has been temporarily
•ithdrawn from public use by the Department of Interior; it is now under the control of the U.S.
•epartnient of Energy (DOE).
687
-------
In March 1989, the DOE submitted a no migration variance petition for test activities to be
conducted at the WIPP facility. DOE has designed the W1PP as a permanent repository for TRU
wastes that are generated and stored at the DOE sites around the country. These wastes consist of a
variety of materials, including tools, equipment, protective clothing, and other material contaminated
during the production and reprocessing of plutonium; solidified organic and inorganic sludges; pro-
cess and laboratory wastes; and items from decontamination and decommissioning activities at DOE
installations.
Section 268.6(a) of 40 CFR states that "petitioners for a no migration variance must demon-
strate, to a reasonable degree of certainty, that hazardous constituents will not migrate from the
disposal unit or injection zone for as long as the waste remains hazardous."1 HPA proposed to inter-
pret this standard to mean that the hazardous constituents cannot migrate from the unit at hazardous
levels.1 In other words, to show "no migration," the petitioner must demonstrate that constituents
released from the unit do not exceed health-based standards at the point where they exit from the
unit. EPA considers the point where the exhaust shaft of the mine meets the surface as part of the
WIPP unit boundary.1 VOC concentrations are monitored at this and other locations throughout the
facility to ensure no-migration via the air pathway.
The WIPP VOC Monitoring Plan4 provides for sampling and analysis to be performed using the
guidance in EPA Compendium Method TO-14.5 This method is capable of detecting the hazardous
constituents targeted for quantitation with a sensitivity below 1 part per billion by volume (ppbv).
Samples are collected in 6-liter SUMMA® passivated stainless steel canisters. The method requires
that all samplers, including pumps, valves, and peripheral equipment, be certified to ensure cleanli-
ness and reliable sample recovery. Samples are analyzed by high-resolution gas chromatography
followed by full scanning mass spectrometry (GC/MS/ SCAN) to provide the capability to identify a
wide variety of VOCs.
Method TO-14 also requires that all samplers be removed from service for routine maintenance
and be leak tested and certified with humidified zero air and humidified gas calibration standards.
The monitoring plan submitted by DOE indicates that all samplers will be certified on a quarterly
schedule.
SAMPLING PROGRAM
Eleven sampling locations originally were proposed to demonstrate no-migration from the re-
pository. At this time, three stations are operational. Biweekly samples are being collected to
gather baseline concentration data at VOC-1 (exhaust shaft). VOC-2 (air intake shaft), and VOC-8
(underground).
Commercially available, dual-canister samplers are used to collect air samples for VOC analy-
sis.6 A schematic of the WIPP multicanistcr samplers and the sampler certification system is pre-
sented in Figure 1. Dual-canister samplers are expandable to accept secondary sampling modules.
In this configuration, up to four canisters can be installed to allow unattended sampling over any de-
sired period, such as a long weekend or holiday, either continuously or on alternating days. In
addition to unattended sampling, the multichannel digital timer and switching solenoid valves enable
simultaneous or collocated sampling for the purpose of estimating sampling precision. The samplers
were modified with a bypass and a 3-way valve to enable simultaneous certification of all sampling
ports. Sampler certification of all sampling ports is important to ensure defensible data for any
sampling port used. In the event that one or more sampling ports fail as a result of mechanical
problems, the remaining ports can still be used with confidence.
SAMPLER CERTIFICATION
Although many steps are required to complete VOC canister sampler certifications (Figure 2) as
specified in the WIPP VOC Monitoring Quality Assurance Project Plan (QAPjP).7 only two are
considered data-generating steps. These steps specified in Method TO-14 are the Humid Zero Air
Certification and the Humid Calibration Gas Standard Certification.
(>88
-------
The total flow rate through the. dual canister samplers is about 2.5 L/min. The majority of this
flow is vented through the bleed air-out port. This high flow rate helps dilute any contaminants
present in the sampler pump and decreases the residence time in the sampler inlet tubing and pe-
ripheral equipment. Approximately 8 cmVmin of sample flow is directed into the SUMMA® canis-
ter via the flow controller, yielding a final canister pressure of approximately 15 psig after 24 hours.
Because integrated 24-hour samples are being collected at the WIPP facility, the certification time
criteria for both humid zero air and humid calibration gas was set at 24 hours. Although this 24-ho-
ur certification criterion presented several logistical challenges for the successful completion of the
sampler certifications, it was deemed necessary to ensure the integrity of the data for the DOE
WIPP VOC monitoring program. Section 11.2.3.8 of Method TO-14 states that "at the end of the
sampling period (normally same rime period used for anticipated sampling), the sampling system
canister is analyzed and compared to the reference GC-MS or GC-muitidetector analytical system to
determine if the concentration of the targeted VOCs was increased or decreased by the sampling
system." In addition supplying sufficient, humidified, high-quality ultra zero ambient monitoring
(U/.AM) air for extended periods was a significant challenge. Reliable, unattended operation of the
certification system (for 24-hotir periods) was another design concern. UZAM cylinders connected
by a manifold were used as the first solution to the zero air supply problem. Later, a commercially
manufactured UZAM generator was purchased and tested to assure the quality and reliability of the
system. Electronic mass flow controllers, improved humidification chambers, and computerized
data acquisition systems were added to facilitate the reliable, unattended operation of the
certification system.
Five target compounds most commonly present in the wastes are currently used in the sampler
certification program: l.l.i-trichloro-l^^-trifluoroethane (Freon 113), methylene chloride. 1,1,1-
trichloroethane (1,1,1-TCA), carbon tetrachloride, and trichlorocthene. If other compounds are
measured at the WIPP facility at a specified frequency, they will be added to the sampler certifica-
tion target list.
Based on the guidance in Method TO 14, the WIPP VOC Monitoring Program criteria have
been established and adhered to for all sampler certifications. Only canister samplers that meet the
established program criteria arc placed into service; therefore, completeness for the sampler certifi-
cation program is always 100 percent.
CERTIFICATION DIFFICULTIES
Of the five target compounds for the WIPP VOC monitoring project, by far the most difficult to
remove from the samplers is 1,1,1-TCA. In an effort to eliminate 1,1.1-TCA from the VOC canis-
ter samplers, a number of procedures have evolved that are designed to overcome contamination.
The methods used to remove sampler contamination included internal purging with methanol and
jeionized water vapor; heating and purging the sampler under vacuum; and complete sampler disas-
;embly, washing with laboratory soap, and baking selected parts in an oven before reassembling,
'tone of these methods was completely successful in removing sampler contamination.
IJccause of individual component testing and the high flow rate through the sampler pump, the
¦ampler pump was eliminated as a probable cause of the majority of the sampler contamination.
Separate component testing indicated that the two components most likely to cause contamination
irobleins were the solenoid valves and flow controllers. Two manufacturers of solenoid valves had
ifferent methods for lubricating their o-rings. One of the manufacturers used a spray lubricant,
,hereas the other manufacturer applied the o-ring lubricant by hand. The spray lubricant was found
j contain 1,1,1-TCA, which permanently contaminated the o-rings. The lubricant applied by hand
/as free of 1,1,1-TCA and did not contaminate the samplers.
In order to eliminate any chance of contamination from lubricants, a literature search was con-
ucted to find an o-ring that would seal without the use of a lubricant. An o ring manufacturer
idicated that Viton® o-rings (normally used in solenoid valves) are mechanically superior to other
laterials; however, they are permeable and will absorb compounds such as 1,1,1-TCA. Engineers
689
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from the o-ring manufacturer confirmed that heating is beneficial for cleaning metal parts, but detri-
mental for cleaning elastomer containing porous materials such as o-rings and diaphragms. Heating
actually increases the permeability of these porous materials. The realization that use of this clean-
ing method for porous materials was actually worsening the problem prompted an immediate change
in procedure. New porous materials were ordered to replace any material that had been previously
heat treated. New Tcflon®-coated Viton® o-rings were ordered to replace the Viton® o-rings in the
solenoid valves. Subsequent zero air certification samples showed that the Teflon*-coated o-rings
made a significant improvement; however, several samplers were still contaminated with
1,1.1-TCA.
Further discussion with the manufacturing engineers revealed that the flow controller diaphra-
gms are made with Kcl-F®, a plastic similar to lhal used to produce 2 liter soft drink bottles. This
plastic, although strong, is very permeable and virtually impossible to clean when contaminated.
As a result of this information, a plastics distributor was requested to fabricate new Teflon®
flow controller diaphragms to replace the Kel-F® diaphragms. The low permeation rate for Teflon®
seemed to eliminate the problem associated with the Kel-F® diaphragms. Results of the subsequent
blank checks on two test samplers confirmed that the Teflon®1 diaphragms were superior to the
Kel-F® diaphragms for cleanliness.
OBSERVATIONS
Section 11.2.2.3 of Method TO-14 states that the humid zero gas stream passes through the
calibration manifold, through the sampling system, and then to the analytical system at 75 cm7 min.
The certification methodology for the W1PP samplers uses a 8 cmVmin flow rate.
As shown in Table 1, the analytical results from one sampler varied greatly depending on the
flow rate through the sampling system. Humid zero air pumped through the canister sampling
system at the Method TO-14 suggested rate of 75 em'/min produced analytical data indicating that
the sampling system was clean and ready for field use. The same sampling system was then chal-
lenged with a test stream of humid zero air at 8 cmVinin for a 24-hour period. Analytical results
indicated that the same "previously clean" sampler had concentrations of 1,1,1-TCA in excess of
4 ppbv. This concentration did not meet the W1PP certification criteria, and was therefore rejected
for field use.
CONCLUSIONS
When stringent sampler certification requirements must be met, it is necessary to pay close
attention to small details that can adversely affect the representativeness of monitoring data. Thus,
both sampler integrity and certification procedures should be carefully evaluated before a VOC
monitoring program is initiated. Close attention must be paid to individual sampler components as
part of the certification process.
Sampler certification data collected from this program suggest that VOC sampler certifications
conducted at high flow rates with shortened time intervals could produce misleading data about the
cleanliness of a sampling system. Subsequent field sampling at low flow rates over a 24-hour period
may produce erroneous data with concentrations of target compounds that are perceived as actual
ambient air values. A portion of the measured concentrations may be attributed to sampler contami-
nation.
REFERENCES
1. U. S. Environmental Protection Agency. Land Disposal Restrictions, 40 CFR Part 268, Code
of Federal Regulations, Office of the Federal Register, Washington D. C.
690
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2. U. S. Environmental Protection Agency. Notice Proposing to Grant a Conditional Variance to
the Department of Energy Waste Isolation Pilot Plant (WiPP) From Land Disposal Restrictions,
Federal Register, Volume 55, No. 67, April 6, 1990.
3. U. S. Environmental Protection Agency. Conditional No-Migration Determination for the De-
partment of Energy Waste Isolation Pilot Plant (WIPP), Federal Register, Volume 55, No. 220,
November 14, 1990.
4. Westinghouse Electric Corporation. Volatile Organic Compound Monitoring Program Plan, WI
12-06, Revision 1, Waste Isolation Pilot Plant, Carlsbad, NM, 1994.
5. Winberry, W.T.,Jr., Murphy, N.T., and Riggan, R.M.; Methods for Determination of Toxic
Organic Compounds in Air EPA Methods, Noyes Data Corporation: Park Ridge, NJ, 1990; pp
6. Scientific Instrumentation Specialists; Preliminary User Instruction for Model TGS-2/A Auto-
mated Two Canister Sampler (July 1990).
7. Westinghouse Electric Corporation. Volatile Organic Compounds Monitoring Quality Assurance
Project Pian, WP 12-7, Revision 2, Waste Isolation Pilot Plant, Carlsbad, NM, 1994.
Table I. Target Compound Concentration vs. Sample Flow Rate
467-583.
Concentration (ppbv5)
Target Compound @ 75 cmVmin
Concentration (ppbv)
@ 8 cm3/min
Freon 113
Methylene chloride
1,1,1-TCA
Carbon tetrachloride
Trichloroe thane
ND-
ND
ND
ND
ND
ND
ND
4.69
ND
ND
ppbv - per faflioQ by volume
ND = Not detected. Detection limit it 020 ppbv
691
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.odOMjsjg
Figure 1. Schemat'c diagram of WIPP Multi-Canister
Samplers and Sampler Certification System.
692
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Figure 2. Certification algorithm.
-------
A Fully Automated SUMMA Canister Cleaning System for Method T014
D-B. Cardin
Entcch Laboratory Automation
950 Enchanted Way #101
Simi Valley, CA 93065
Cleaning SUMMA passivated canisters used in EPA method TO 14 is required
to prepare them for reuse as a field sampling container. This process requires several
cleanup and quality assurances steps, including initial leak checking of the manifold
alter canister attachment, preliminary evacuation of the manifold with valves closed to
insure leaktight valves, cycling between filling and evacuation to (lush out
contaminants, high vacuum pump down to finish contaminant removal, and standby
monitoring to verify the absence of leaks in the canister welds. This procedure can
require a lot of technician attention and is subject to human error when cleaning large
numbers of canisters.
A system is presented that automatically performs the functions described
above while recording all pressures and vacuums to a OA report. The only interaction
required by the operator is to open the canister valves after the first rouud of valve
leakchecking is completed. The canister cleaner uses a molecular drag pump to
perform evacuation of 8 to 12 canisters simultaneously down to 10-20 mtorr. Flexible,
all stainless tubing is used to connect each canister to the 3/8" diameter manifold
allowing canisters of virtually any size and shape to be cleaned. Canister heating and
humidification of flush gas are performed to assist in displacing heavy or polar VOGs
from canister surfaces. Discussions will be focused around the improvements in quality
assurance and cleaning consistencies relative to manually operated systems.
694
-------
Networking an Entire T014 Laboratory into a Single
Windows-Hased Control System
DM. Cardin, J.T. Deschaifis, and E.A. Gatousiian
Enlcch Laboratory Automation
950 Enchanted Way #101
Simi Valley. CA 93065
El'A Compendium Method 7014 specifies the analysis of Volatile Organic
Compounds (VOCs) in ambient air as collected in SUMMA passivated stainless steel
canisters. In order to perform Method TOW, provisions must be made for field
collection of samples in canisters, preconccntration and analysis of the VOC fraction
in the canister, cleaning of the canisters for reuse, and preparation of analytical
standards for method validation and GC/'MS response factor determination. The
temporary oi long term loss of any of these capabilities within a laboraloiy will cause
a bottleneck and ultimately delay operations until alternatives can be found. Even
when successfully completing each of these tasks, a laboratories ultimate efficiency
and profitability will be determined by sample throughput which will be hindered bv
the task that is the least automated.
A novel approach to instrument communications is presented that makes it
possible to monitor and control field sampling, canister cleaning, standard preparation,
and pieconceiiUatioii and analysis systems in a T014 laboratory using a single IBM
compatible PC operating under Windows™. The network permits communication with
microprocessor based devices, such as 32-position aldchydc/sorbcnl tube samplers and
16-position canister field samplers, for transfer of new program information and
recovery of field collected data. Canister cleaning operations arc improved by
providing feedback and control of leak-checking operations, mass dilution
canister cleaning, and final high vacuum evacuation without user intervention.
Generation of standards by dynamically diluting an MST traceable ppm level
standard to ppb levels is supported with provisions for autocalibration of mass How
controller channels for ultra-accurate VOC blends. Full communication and control of
a 3-stage '1014 preconcentrator is also supported with extended QA/QC protocols and
diagnostics for improved uptime and performance. An overview of the system will he
presented with primary attention paid to enhancing TOM laboratory productivity.
-------
Advanced Surface Treatment and Cleaning Techniques fur the
U.S. EPA xVIethod TO-14 Grab Sampling Containers
Joseph Krasnec
Scientific Instrumentation Specialists
P.O. Box 8941
Moscow, ID 83843
Increased demands and an expanding list of toxic organic compounds,
including oxygenated organics and other special groups, e.g., organic sultur
compounds, require modifications and improvements to the existing sampling and
measurement hardware. One critical area is the passivated stainless steel surface of the
grab sampling containers. The established and proven dectropolishing (SUMMA
passivation) works well for the sampling of hundreds of organic and inorganic volatile
compounds. However, there arc instances (i.e., some oxygenated organics) where the
normal passivation falls short of the required stability and storability requirements.
Uccent R&l) efforts show some promising avenues of improvement for the surface
treatment and cleaning of the sampling containers. The passivated surface can be
coated with several inorganic materials to enhance its performance. The initial work
shows performance improvements for some groups of organics. but not an
acioss-tlie-board enhancement. The effect of surface saturation with water vapur and
othei materials has also been investigated. Some novel surface cleaning techniques
have been explored with encouraging results. This paper will attempt to bring the
audience up to date on some of the above discussed efforts.
696
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SESSION 16:
AMBIENT AIR MEASUREMENTS OF VOCS
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Intentionally Blank Page
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Determination of Volatile Organic Compounds in Ambient Air with Gas
Chromatograph-FIame Ionization and Ion Trap Detection
Shili Liu, Robert J. Carley, Jiangshi Kang, Jinnpiiig Chen and James D. Stuart
Environmental Research Institute, the University of Connecticut, Route 44, I.ongley Building, Storrs,
CT 06269-3210
ABSTRACT
Two new techniques are utilized to integrate the following three equipments: an Ontech 2000
automated air concentrator, a Hewlett Packard gas chromatograph (GC) with flame ionization
detector (FID) and an ion trap mass spectrometer detector (ITD). This combined analytical system is
used to determine low ppb level volatile organic compounds (VOC) in ambient air. The first
technique is to configure the inlet system of the GC, so that the pressure regulated flow control
system of the GC injection port is used to control the flow of both the desorb gas of the automated
air concentrator and the earner gas of the GC column. The injection port still can be used to inject
gas and liquid samples directly. The second technique is to split the effluent of GC column at a 1:1
ratio to the ITD and the FID In this way, both FID and ITD data can be obtained for each analysis.
For ambient air non-methane hydrocarbons monitoring, the FID detector is widely used. Oxygen
containing and halogenated organic compounds cannot be differentiated by FID detector and would
be quantified as coeluting hydrocarbons. However, volatile organic compounds other than target
hydrocarbons can be identified by 1'ID, This analytical system is very valuable research tool for non-
methane hydrocarbons and urban air toxic monitoring. The performances of this developed system
have been presented
INTRODUCTION
The Environmental Research Institute of the University of Connecticut has been conducting a
cooperative monitoring program with the Air Toxic Group of the Bureau of Air Management,
Department of Environmental Protection, State of Connecticut. In the volatile organic monitoring, in
addition to the determination of the concentrations of toxic compounds (halogenated, aromatic and
other common solvents) and ozone precursors (non-methane hydrocarbons), confirmation analyses for
back-up canister sample from field continuous monitoring in PA>1S (photochemical atmospheric
monitonng study) study
is also required.
In air toxic monitoring , mass spectrometer (GC/MS) is usually required In the GC/MS
method, target compounds are identified and quantified by combining the information of retention
•ime from gas chromatograph and characteristic ions from mass spectrometer Non-target compounds
;an be also identified tentatively. But in a low resolution mass spectrometer, nitrogen and carbon
iioxide background ions, may interference the analyses of ambient level C2 to C3 hydrocarbons,
;inc.e the masses of their fragment ion are very close In the PAMS study, C2 to CIO hydrocarbons
n the ambient air sample are analyzed using a gas chromatograph with a flame ionization detector
FID), retention time is the only information for qualification. Since the response of a FID for a
ivdrocarbon is proportional to the number of carbon in its molecule, this simplifies the calibration
•rocedures for quantification However, a compound other than target hydrocarbons may be
lisidentified as a target hydrocarbon, if retention times of these two compounds are close enough.
699
-------
In this work an analytical instrument system and a methodology have been developed to
analyze both C2 to CIO hydrocarbons and air toxic compounds Two new techniques were utilized
to integrate the following three equipments an F.ntech 2000 automated air concentrator, a Hewlett
Packard gas chromatograph (GC) with flame ionization detector (FID) and an ion trap mass
spectrometer detector (ITD). The first technique was to configure the mlet system of the GC, so that
the pressure regulated flow control system of the GC injection port can be used to control the flow
of both the desorb gas of the automated air concentrator and the carrier gas of the GC column The
injection port still can be used to inject gas and liquid samples directly. The second technique is to
split the effluent of the GC column at 1:1 ratio to the ITD and the FID. In this way, both FID and
ITD data can be obtained from each analysis. An open split interface was used to combine GC and
ITD. The interface was optimized by the manufacture to introduce less than 1 ml/min column flow
into ITD, the rest is vented. The GC column flow was around 2 ml/min. After 1:1 splitting, the flow
enters the ITD is around 1 ml/min, so about same amount of analytes introduced into ITD and no
significant sensitivity loss As both inlets of ITD and FID are near to atmospheric pressure, the split
ratio can be easily controlled by using two pieces of deactivated fuse silica tubing with the. same
inner diameter and length This analytical system is a very valuable research tool for hydrocarbons
and air toxic compounds monitoring. The performance of this developed system is evaluated.
EXPERIMENTAL
Instrumental
Automated Concentrator. An Entech 2000 Canister Automatic Concentrator (Entech Inc Sinii
Valley, Ca) with a micro-purge ar.d trap module. Air sample is first trapped in a liquid nitrogen
cryogenic trap packed with glass beads The trap is then heated up to room temperature. A small
nitrogen flow is used to purge the trapped organic compounds onto a sorbent trap. In this step , only
small amount water is transferred. A dry gas flow is used to further remove moisture on the. sorbent
trap. The sorbent trap is then thermally desorbed Organic compounds arc cryofocused on a liquid
nitrogen trap before injected into GC column The temperature and flow conditions are as following:
Glass bead trapping temperature:
-160OC.
Sorbent trap temperature.
-50OC.
Cryofocusing trap temperature:
-130QC.
Glass bead trap desorb temperature:
J0OC.
Glass bead trap desorb flow:
125 ml (at 25 ml/mm).
Sorbent trap desorb temperature:
170OC.
Sorbent trap desorb time:
4.0 min.
Sample injection:
2.5 min at GC column flow
Gas Chromatograph Hewllet Packard 5890 gas chromatograph equipped with a splitless
injection port, a flame ionization and a liquid nitrogen oven cooling valve An HP-5 capillary
column (made by Hewllet Packard Inc.) with 0.32 mm inner diameter, 50 m long and l.C um film
thickness, was used for the analysis Head pressure of the column is 15 psi, column flow rate is
about 2 ml/min.
The temperature program arc as following:
Initial temperature -15 OC for 2 min
Step 1: to 0 oC at 15oC/min, held for 2.0 min.
Step 2. to 60oC at 4 oC/min.
Step 3: to 200oc at 7 OC and held for 4.0 min.
700
-------
Ion Trap Mass Spectrometer Detector. A Perkin-EImer ITD Ion Trap Detector with an open
split GC interface was use. The ITD is tuned to 1,4-Bromofluorobenzene criteria. The mass scanning
range is from 26 to 350 m/z at J.O second/scan. The multi-points external standard method was used
for quantitative analyses.
Svstem Configuration. Figure 1 shows the diagram of the system. The injection port of the
GC is unmodified and fully utilized. A piece of 0.53 mm ID deactivated fuse silica tubing is
installed to the outlet of the injection port as a normal capillary column, its end is connected with the
carrier gas inlet line of the Entcch 2000 automated sampler via a union. The sample transfer line
from the Entech 2000 is connected with the inlet of the analytical column using a zero dead volume
union. At the outlet of the analytical column a stainless steel Swagelock 1/16 Tee is used to split
the column flow. At each end of the Tee, a 0.32 mm id. 0.5 m long deactivated fuse silica is
connected. The other ends of the two pieces of fuse silica tubing are connected (o FID and ITD
respectively.
Calibration Standards
Stock Vapor Standards. The vapor standards with concentrations at ppm level were prepared
with the static dilution method. A few microliters of each liter neat liquid compound is injected into
a 2.00 liter static dilution bottle containing carbon filtered nitrogen The mass of a compound added
can calculated from the volume injected and the liquid density. A 2 ppm VOC standard gas mixture
(ALPHAGAZ Division of Liquid Air Corp.) containing 42 target compounds in air toxic monitoring
is also used as stock standard.
Working Standards. Working standards at lower ppb level are prepared by inject small
amount stock standards into an evacuated Summar canister and then filling the canister with
humidified carbon-filtered zero grade air. The total dilution volume is calculated from the volume
and the final pressure of the canister A concentration of 10 ppb working standard mixture in a
Summar canister is used to prepare at least a four- point calibration curve by introducing volume of
200 to 1000 ml Another standard prepared separately is used as a calibration verification standard. A
calibration usually can be used for a month Two types of standard mixtures are used, one contained
42 target compounds of method TO-14 plus bromodichloromethane, chlorodibromomethane,
bromoform and 5 polar compounds, which are acetone, acrylonitrile, 2-butanone (methylethylketone
MEK). methyl isobutyl ketone (MIT5K) and methyl methacrylate The second standard mixture
contains C2 to C10 hydrocarbons, which are target compounds in PAMS study Both standard
mixtures are analyzed under the same conditions. An unknown sample is analyzed once and
calibrated against each group of standards. Two sets of results can be obtained
Reference Standards. A standard vapor mixture containing 18 volatile organic compound at 5
ppb, which are traceable to National Institute of Standards & Technology (MST) primary standard, is
used reference standard to check the standard prepared in the laboratory.
RESULTS AND DISCUSSIONS
Recoveries of Reference Standard
Table 1. shows typical recoveries of both FID and ITD. In oui laboratory, 70 to 130 percent
-ecovenes are used as quality control criteria. In most cases, these criteria can be achieved.
Sometimes, after repeated preparation of standards from stock standard.
701
-------
Comparison Criteria
The values of a compound from the same analysis but two different detectors, PID and TTD,
always has difference. The question often asked is what difference can be considered significant.
Criteria need to be established, before the evaluation of the data. The following procedures were used
to establish the criteria in comparison of the values of the same compounds from the two detectors
1) Estimate the standard deviation of every' compound on both detectors respectively by
repeatedly analyzing the same concentrations and using the following equation:
Where: s - standard deviation.
X - average of individual measurements Xi.
n - number of repeatedly analyses
2) Calculate standard error of the difference between two measurements for each compounds:
3) Estimate the difference with the confidence level of 95%:
Z.;.„-,,s\,.x;, (here the Z = 1.645)
When the difference of two values from 1TD and FID for the same compound is equal to 1.646 timer,
of standard error, the difference can be considered as greater than zero with 95% confidence level
A standard mixture with concentration around 1 ppb, common concentrations for a volatile
organic in ambient air samples, was analyzed 7 times. The standard error of the difference between
FID and ITD measurements for each compounds is calculated using the above equations. Figure 2
and Figure 3 illustrate the results. The standard errors for most compound are less than 0.4 ppb.
When the difference of FID and ITD measurements for a compound, which concentration is around 1
ppb, is less than 0.4 ppb, the difference can be ignored. In Figure 2, no data for methylene chloride,
carbon tetrachloride, cis-dichloropropene and chloromethylbcnzene, due to unresolved peaks The
difference for m-xylene is twice that of the other compounds because in the standard mixture
contains both m-xylene and p-xylene. The ITD is not capable of differentiating, the actual combined
concentration is about 2 ppb, so the standard errors is also doubled.
Comparison of Results from Different Calibrations
In PAMS study, the calibration is simplified by using an average response factor (ppbe/peak
area) of a few compounds to calculated all other compounds concentration in a sample This
simplified calibration method is based on the fact, that the response factor of FID is about the same
for all hydrocarbons, when the concentration is expressed as ppbc, ppv multiplied by the number of
carbon m a hydrocarbon molecule. In our work each hydrocarbon is calibrated individually, using
multi-points calibration prepared from standard of the compound The simplified calibration method
is also used to calculate the pph concentration by dividing the ppbc concentration with the carbon
number of the compound. Results froir. different calibration methods are tabulated in Table 2. In the
table for unresolved two peaks, the both ppbc and individual FID results are calculated as first
compounds. The last column, range, indicates the largest difference among reference value, ppbc/c,
ppb by ITD and ppb by FID. A range, which is greater than 40% of reference value need be
S' vs,; + s,'
707.
-------
examined closer, is denoted by an asteria I.arge differences are often caused by unresolved peaks in
FID, in this case ITD shows some advantages The ppbc results for compounds which retention time
is longer than toluene, show relatively low concentrations. The possible reason is that these heavier
compounds have relatively lower transported efficiencies. This effect can he compensated for by
using an individual calibration, because standards also suffer the same processes , bul not by using
a universal response factor method.
Conclusions
This analytical system has the following advantages:
1) The original GC column flow control system is fully utilized.
2) Injection port still can be used for direct injection.
3) Both ITD and FID results can be obtained in one analyses
4) A routine method is provided for both air toxic and hydrocarbons analysis.
This analytical system is a good tool for VOC analyses in air and for real time comparison of FFD
and mass spectrometer m VOC analysis More ambient sample analytical data are needed to evaluate
this system.
Acknowledgements
We thank David Gregorsky, Jim Ellis, Louis Scarfo and Michael Murphy, of the Air
Management Bureau, Department of Environmental Protection, State of Connecticut, who provide
full support for this work.
-------
Table 1. Recoveries of Reference Standards Traceable to NIST Primary Standards
Compounds
Cert. Cone.
ITD
FID
ppb
Cone.
% Rec.
Cone.
% Rec.
Vinyl chloride
4.91
4 85
98.8
4.81
98.0
Bromomethane
S.27
5.27
100.0
4.95
93.9
Trichlorofluoromethanc
5.20
4 84
93.1
4.75
91.3
Methylene chloride
4 56
448
98.2
4 94
108.3
Chloroform
4 91
4 41
89.8
4 29
87 4
1,1,1 -Trichloroethane
5.45
485
89.0
4 58
84.0
1,2-Dichloroethane
4.87
5.12
105.1
4.78
98.2
Benzene
4.93
4.84
98.2
4.43
89.9
Carbon tetrachloride
4.08
485
118.9
4.43
108.6
Trichloroethene
5.12
4 69
91.6
4 59
89.6
1,2-Dichloropropane
4.70
4.75
101.1
4 59
97.7
Toluene
5.05
5.04
99.8
4.90
97.0
1,2-Dibromoethane
4.84
4.07
84.1
3.94
81.4
Tetrachloroethene
5.01
4 90
97.8
5.70
113.8
Chlorobenzene
5.10
5 03
98 6
4 89
95.9
F.thylbenzene
4 89
4 88
99 8
4.46
91.2
o-Xylene
5.30
5 17
97.5
4 73
89 2
Cert. Cone. - certified concentration
%Rec. - percentage recovery
704
-------
Tabic 2. Comparison of Results from Different Calibrations
Compound
RliF
ppb
f!C
ppbc
ppbc/c
ITD
ppb
FID
ppb
Range
Plib
Elhvlenc
10.1
2
21.1
10.5
11.2
III
1.1
Ethane
10.1
2
29.0
14.5
22.0
30.0
19.9 *
Propylene
lo.n
3
22.6
7.5
9.0
9.4
2.5
Propane
1-Butcnc
10.1
foT
3
~4~
47.8
43T
15.9
mj~
9.0
9.1
10.8
iT5X
6.9 *
1.8
n-Butanc
97) 1 4
46.6
11.6
9.0
10.1
2.6
lrans-2-Butcne
S.2
4
36.4
9.1
84
9 1
08
cis-2-Butene
9.2
4
35,2
8 8
8 6
9.1
0 6
3-Metliyl-l-Butene
15 0
5
79 1
15 8
14.0
14.8
1.9
Isopviitanc
16 1
5
89.1
17 8
14.6
16.2
3.2
l-Penleno
10.0
5
I" 44.8
9.0
8.4
9.7
1.6
n-Penlane
10 0
5
51.1
10.2
8.8
10.0
1.5
Isoprcne (1)
18.7
5
139.8
28.0
15.5
34.7
19.1 *
trans-27entenb (2)
173
5
15,2
2.1
cis-2-Pcntcne
173
5
69.3
139
15.9
16.7
3.5
2-Methyl-2-Butcnc
176
5
683
13 7
15.7
17.1
4 0
2.2-Dimethv'butane
14.1
«
87,8) 14 6
12.9
14.0
1.7
Cylcopcnlcnc (1)
180
5
119.1
23 8
16.2
32.1
15 9 *
4-Methyl-l -Pentene (2)
14 8
6 ! !
12.6
2 1
2.3-Dimethvibutane
144
6
78 8
13 1
12.7
14 2
1 7
Cvclopentnne
20 0
5
99 2
r 19 8
18 5
it; (i
1 5
/-MefhvlpeiUane
14 2
6
84 5
14 1
12.9
13 9
13
3-Mu;hvlpenta;ie
I- 14.4
6
8541
L 142
13.0
14 2
1 4
2-Mcthy-l-l'cnlcnc
is ,r
£>
58 7
y.sl
14.2
15 0
5.3 -
n-Hcxanc
y. y
6
54.5
9.1
9.1
10.2! 1.1
lrans-2-Hexcr.e
7.0
6
30,0
5.0
7.8
6.6 1
2.8 *
cis-2-iIcxenc
20.1
6
81.1
13.5
19.1
18 0
6.6 *
Mehlylcyelopcntane CI)
16.6
6 i 188 1
31.3
16.0
28.7
15.3 »
2.4-Dimelhvlpcntane (2)
12.5
7 1
11.2
1.3
Cyclohexane (1)
17.3
7
193.7
27.7
16.2
39.1
22.9 *
benzene(2)
210
6
21.6
0.6
?.-Vfehtvlliexanc
13 0
7
81.3
11.6
11.7
12 6
1.4
?,3-Dimethylpenlanc
13.0
7
97 7
14.0
17.0
12.7
19
3-Melh}lhc\ani-
12.8
7
85.5
1.2.2
11 3
12 5
1.5
2,2,4-TnmcIhlpcnUinc
11.3
8
93.7
11.7
10.0
11.0
1.7
n-Heptane
12.8
7
69.4
9.9
12.2
13.4
3.5
Methylcyclohexanc
14.7
7
100.1
14.3
13.2
14.2
1.5
2,3,4-T rimedtvlpentane
11.8
8
90.8
11.4
10,5
11.4
1.2
2-Metlivll;epiane
11.4
8
79 5
9.9
113
111
1.5
3-Metlivlheptniie
11.4
8
82.8
10.4
125
14.$
4.5 *
Toluene;
17,6
7
78.2
11.2
160
15 9
6.4 *
n-Ociane
11.5
8
70.1
88
10 3
11.7
3.0
Elhylben/cne
15 3
8
69.0
8.6
14 3
15 7
7.1 ~
nv p-Xyiene
12.0
8
78.5
98
13 71
15 5
5.7 »
n-Nonane (l)
10.5
9
113.9
12.7
9 9
26 5
16,7 »
Styrcne (2)
16.2
7
14 0
2.2
o-Xvlenc
15.5
8
97.8
12.2
14.2
15.4
3.3
Isopropyibenzcnc
13.4
y
83.2
9.2
12.3
13.3
4.2 *
aipha-Pinenc
11.8
10
99.4
9.9
11.3
11.2
1.8
n-Pronvlben/.ene
13.4
5
72.6
8.1
12.4
13.4
5.4 «
1,3,5-Tnmethylben?enc
13.4
9
74.4
83
13.5
13.7
5.4 »
befa-Pinene
118
10
85.4
8.5
10.9
11.3
3.2
1,2,4-Tnmethylbenzenc
11. if
i>
66.6
7.4
D.6~
14.1
6.7 *
NOTF/ * indicate> a range is grater than 40% of its reference value.
(1) peak* not rcsolutcd with GC, reported ?.s sum of two compounds for FID results
(2) Peaks not rcsoluted with GC, only ITD result available
705
-------
Figure 1. CONFIGURATION OF THE SYSTEM
carrier gas injection port
Entech 20U0
HP-5 column
IJninn
_ J
to FID
to ITD
1/16" Tee
706
-------
Figure 2. Difference with 95% Confidence at lppb
[ppbj
0 00 0 10 0.20 0.30 0 40 0.50 0 60 0.70
hexachloro-t .3-butadiene
1,2,4-trichiorobcnzenc
1 ,2-Dichlorobenzenc
chlorornethylbcnzcne
! .4-iiichlorobenzej:c
1,3-dichlorobcnzene
1,2,4 - tri methyl benzene
13yS-u i mcth> 1 benzene
! -clhyl-4-methyl-benzene
1,1,2.2-tetrachIoioctliajie
o-Xylene
Styrenc
fciomotbnrri
in-xylene
L'thyJbenzene
Chlorobcnzcnc
Tetrachloroethcne
1,2- dibromoethane
dibromochloro methane
1,1,2-irichlcrcethanc
Toluene
turns i ,3-dichlc>ropiopene
cis-1,3-dichIoropropene
Methyl mcthacryiate
M1HK
bromodtchtoromethane
i,2-Dichloropropane
TnchloroefJbene
Carbon tetrachloride
Benzene
1,2-Dichloroclhane
1,1,1-Tnchlcroethane
Chloroform
cis-1,2-dichlorceihene
2-Ri:tanoiie(MRK)
J, UDichloroc thane
Methvlenc chloride
3-cfiloro- i -propene
. ,2-trichIoro-trifiuoroethanc
Acrylonitrile
1,1-Dichloroethene
Acetone
tnchlorofluoiomc thane
chlorcethnne
hiomomcthane
chloroethcne
2-dichlorotctratluoroc thane
chloromelhane
(1 ich! orod i H uorcnnediane
707
-------
Figure 3. Difference with 95% Confidence at 1 ppb
1.3.5-Trimcihylbcn/cnc
n-Propylbcn/.cnc
alpha-Pinene
isopropylbcnzcnc
o- Xylene
Sryrcne
ii-Nonane
triT /or p-Xylene
bthylbenzene
n-Oclanc
? -Mcthvlhcplanc
Toluene
2 Metliylhcplane
2.3.4-T rimel hylpcntanc
Melh) Icvclulscxane
n-I Icpiane
2.2,4-Tumelltylpcntane
3-Melhyihcxanc
2.3-L!uiieil]ylpeiitane
2-Meht> Ihexanc
Benzene
Cyelohcxane
2.4-l)nneth;lpeulaue
Mehtylcyc'npcntane
cis-2-Hexene
trans-2-llexene
n-Hexaiie
2-Mclhy-l-Pcntenc
.i-Maliylpentaue
2-Mcthylpcntanc
Cyclopentane
2.3-DimclhySbutane
4-Melhyl-1 -Pentene
Cylcopcntenc
2,2-Dimcthylbutaise
2-Methvl-2-Butcnc
cis-2-Penler.e
traos-2-Pentsne
lsoprene
n-Pcntanc
1 -Pcnieiie
Isopcntane
i-Methvl-l-Butene
cis-2-Butcnc
tMns-2-Bulcne
n-Butane
1 -Butcne
Propane
Propylene
HUiar.e
Ethylene
frnmm^innrrininiDHfflfflraiimufflinfiMifflimnnmii
?,\wm
Tiramiraifip*!
pirF W! -r 'till. 'Ilia
WSMSWi
0.00
0.10
0.20
0.30
ppb
0.40
0.50
70S
-------
Exposure to Evaporative Gasoline Emissions
Clifford P. Weisel and Krishnan R. Mohan
Division of Exposure Measurement and Assessment, EOHSI, Robert Wood Johnson Medical
School, TJMDNJ, 681 Frelinghuysen Road, Piseataway, NJ 08854
INTRODUCTION
Exposure to evaporative gasoline emissions that occur in selected microenvii onments or
during specific activities can contribute significantly to the daily volatile organic compounds
(VOCs) exposures an individual receives. Three mieroenvironments/activities that are influenced
by evaporative gasoline emissions are residential garages, public parking garages and activities
surrounding refueling of an automobile. In addition, exhaust emissions contribute to public
parking garage air concentrations. The emissions that occur within a residential garage can also
penetrate into the attached home. This penetration lias been observed within samples collected
as part of the TEAM study. Gasoline emissions are one of the major sources of general
population VOC exposures, acute higher environmental exposures and as VOC sources into the
home indoor microenvironmental. The data presented are preliminary results from a study
designed to measure the potential VOC exposures in the above mentioned inieroenvironments
and obtain a data base suitable for evaluating mathematical models describing human exposures
from mobile sources.
EXPERIMENTAL
Measurements of the benzene and toluene air concentrations were made within each
microcnvironments/activitv using integrated adsorbent trap samples (trilayer adsorbent of Tenax
GC, Carboxen 569 and Carbosieve Sill) analyzed by thermal desorption (PH-ATD400) coupled
with GC/MS (HP 5890-MSD) and/or with a portable gas chromatograph (MSI 301) that collects
an air sample approximately every eight minutes. The latter is being used to evaluate temporal
changes within the microenvironment. In addition to provided average concentrations the
adsorbent trap thermal desorption/GC/MS method provides a quality control check on the peak
identification and concentration measured by the portable GC. The integrated samples were
collected using a constant flow, personal air sampling pump whose calibration was verified
before and after use using a bubble flow meter and whose flow rate was adjusted to provide
between 0.5 and 3 liters of air, based on the predicted sampling time. A minimum of a five
point calibration curve was prepared for each compound to be measured by GC/MS and the
calibration curve check daily. A blank trap was transported to the field each sampling day and
analyzed to assure that no contamination of the traps were present. The MS settings were
checked using broino-fluoro benzene, as outline in EPA method 625. A multi-point calibration
curve is prepared and saved in the memory of the portable GC. The response of the portable
GC was verified daily by use of an air sample with a known concentration. The zero response
of the portable GC was check by attaching a tube containing activated charcoal to its intake port.
RESULTS
Residential Garage Study
The benzene and toluene air concentrations within a residential garage and the room
adjacent to the garage in tlie attached home were measured before and after an automobile
709
-------
entered the garage and the garage door was closed. These studies were done during the summer
months, since evaporation from the fuel tank is increased when the ambient temperature is
higher. The air concentrations of both benzene and toluene were elevated in the garage after
a ear was parked in it, to as much as SOfig/m' and 150/ig/m3, respectively, (figure 1). This
elevation represented an increase of two to ten time the concentrations present in the air before
the car entered. Air concentrations within the home also increased, approximately twice the
concentration present before a car entered the garage (figure 2). The increase in the air
concentration is rapid and is reaches a maximum value that is a function of the emission rate
front the automobile and the air exchange out of the garage. The concentration subsequently
declines in an exponential fashion (figure 3). The integrity of the fuel system affects the
emission rate and thus the maximum concentrations obtained in the garage. Samples collected
during the summer of 1992 using an older vehicle whose controls systems had probably been
comprised resulted in mg'm3 levels being measured in the garage, two orders of magnitude
greater than presented here.
Public Parking Garage Study
Air samples were collected within a multi-level public parking garage. The upper two
levels were open on two sides, while the lowest level was enclosed on all four sides, with the
access ramp in the middle of the garage. The garage chosen is usually full to capacity during
the day time hours with a mixture of individuals who use the garage for the entire day and those
that park for short time periods of less than one hour. Automobiles often idle within the facility
while waiting for a parking spot to be available. The air concentrations have contributions that
are expected to be a mixture of exhaust and evaporative emissions, with the latter more prevalent
during the warmer months, and a heavier odor of gasoline is apparent during the summer
months. Levels of benzene exceeded 150 fig/m1 and of toluene 500 jig/m' within the garage
(figure 4). The air concentrations were higher in the summer months than the winter, suggesting
the importance of an evaporative emission contribution to the observed levels. The variability
in tlte concentration within a three hour time period on a single day, on two levels with different
ventilation was measured using the portable GC, A greater concentration, along with greater
variability in that concentration was observed on the level that had less ventilation (figure 5).
These measurements indicate that "high" acute exposures can occur within a public parking
garage but that design of the facility to minimize the air concentration can he accomplished by
not enclosing the facility completely.
Refueling Study
Adsorbent trap air samples were collected within an automobile prior to, during and after
refueling and a personal sample was collected from an individual who either refueled his/her
own car or stood next to the service station attendant during the refueling operation. The
automobile interior samples collected prior to refueling were similar to values that we have
collected previously within an automobile being driven in New Jersey. The concentration in the
interior of the automobile was higher during and after refueling than before refueling. The
personal samples were highest (figure 6). An examination of the ratio of benzene to toluene in
tlie air samples indicated that a ratio greater than 1, was present during and after refueling, while
a ratio more typical of ambient, air 0.3, was observed prior to refueling. This difference is best
explained by an increased contribution of evaporative emissions compared to exhaust emissions
to the during and post refueling samples, since benzene is a more volatile compound than
710
-------
toluene, even though toluene is present in the fuel in a higher percentage. Refueling of gas tank
results in an acute exposure to gasoline derived VOCs, which can persist within the automobile
following refueling.
Exposure Estimates
Daily estimates of benzene exposures can be made based on concentrations and time spent
in various microenvironrnents and compared to what might result from ihc microenvironrnents/
activities studied here (Table I). The largest exposures to VOCs occur indoors, since the
majority of a person's time is spent there. Driving in traffic has been shown to contribute more
than 10% of a person's exposure. Spending 10 minutes in a residential garage, with a well
maintained car could contribute an additional 4% and infiltration to a home another 8%. If the
automobile used has a compromised control device on the fuel tank or if the more time is spent
in the garage the exposure level can be considerably higher. Walking within a public parking
garage to and from a car and driving to find a parking spot could contribute more than 10% of
the daily exposure, with the type of ventilation within the garage being an important controlling
factor in the exposure. An individual who refuels a car can receive as much as half of the daily
benzene exposure accumulated on that day from that five minute activity. A small contribution
can also results to individuals who remain in their automobile during refueling
SUMMARY
Three specific microenvironrnents that are impacted by gasoline emissions were studied
and each found to have elevated concentration of VOCs because of those emissions, relative to
ambient air and indoor air. Even spending a small amount of time in these microenvironmenl
could make a measurable contribution to a persons exposure to VOCs. Additional work is on-
going to collect data in these microenvironrnents to evaluate models that predict overall
exposures to VOCs from gasoline emissions.
ACKNOWLEDGEMENT
Although the research described in this article has been funded wholly or in part by the
US HPA-AREAL under a cooperative agreement (CR82035 01) to UMDNJ-RWJMS-EOHSI,
it has net been subjected to the Agency's peer and administrative review and therefor may not
necessarily reflect the views of the Agency and no official endorsement is to be inferred.
711
-------
RESIDENTIAL GARAGE STUDY
Benzene & Toluene Concentrations
adsorbent trap - GC/MS
?oc~
H 150
ICQ
¦C?' of X*' vnT' ¦$-
-\v ^ ^ V v
Sampling Date
Figure 1
jp
&
*$?
No Car-Beri?ene
Car-Benzene
No Ca'-Toluene
Car-Toluene
RESIDENTIAL GARAGE STUDY
Benzene Concentrations
adsorbent trap - GC/MS
oOj -
o .
• 50)
?40l
s f
I30)
c 101
O I
ft* «¥> f? 4s .VI- «
^ ^ ^ ^ ^ ^
P
Sampling Dote
• No Car • Garage
• Car ¦ Garage
' Nc Cm House?
• Car - House
RESIDENTIAL GARAGE STUDY
Benzene Concentrations
portable GC
Concentration pph
V Ca,ib st^ 225 Lfl/m—3
E 2001 • |
c 150
D
2 100
o
" 50
Car Entered Garage
\
¦> Integrated Samols I
Uxe-K V + * KiMC-^**3
" cUlA24-_u^^^===!=^^l.,
<4^ ^ <5^ ^ ^
.^9 *
s* n- n- s* v
-------
REFUELING STUDY
adsorbent trap - GC/MS
¦ft too'Benzena
Toluene
¦ Prior
L.J During
B Personal
H After
Sampling Dny
Figure 5
PUBLIC PARKING GARAGE
Benzene Concentrations
portable GC
160
» 140
t,s0
^ 100
1 60
2 60
S
u 20
0
* +
IntogrniRrf Vntua
10Dyg/m#,3
K, - I
Level 3c
Partly Open
i i
t + <
Uv.l 2 CIOJ.O , + Vnlu«
27pg/m*«3
Zmio
Check
^ ^ ' s-V <<-' <<-• v <• ^ ^
Sampling Time
Figure 6
TabJ e 1
DAILY BENZENE
EXPOSURE ESTIMATES
Influence of residential garage:
in garage for 10 minutes
25/ig/m**3 x 0.2 hours = 5
increase in house for 2 hours
5 pg/m**3 x 2 hours = 10 /jg/m**3
Public parking garage
in garage for 20 minutes
60jjg/m**3 for 0.3 hours = 18 pg/m*
(ventilation affects conc. - time to
find a parking space and walking)
penetration into attached building ???
Refueling an automobile
self service for 5 minutes
1000/vg/m**3 x 0.08 = 80 /ug/m**3
in car full service
50 jjg/m**3 x 0.08 = 4 #jg/m**3
+ post refuel residual exposures
-------
Hydrocarbons in the C8-C20 Range Measured During COAST Study in Texas
B. Ziclinska. J. Sagebiel, L.H. Sheet/, G. Harshfield and E. Ubcrna
Desert Research Institute, P.O. Box 60220, Reno, NV 89506
W.J. llauz.c
North American Weather Consultants. 1293 West 2200 South, Salt Lake City, Utah 84119
J.H. Price
Texas Natural Resource Conservation Commission, 12124 Park 35 Circle, Austin. TX 78753
ABSTRACT
Hydrocarbons in the CK-C2U range were collected using Tcnax-TA solid adsorbent cartridges
during, the Coastal Oxidant Assessment for Southeast Texas (COAST) field study, carried out in the
Houston Galveston and Beaumont Port Arthur areas. Ambient samples were collected at the
Galleria, Clinton and Port Arthur sampling sites. from August 26 to August 30, 1993. In addition, a
number of Tenax samples were collected in the vicinity of major industrial complexes (such as
Exxon, AMOCO Oil, Union Carbide, Dow Chemical) and in an urban tunnel. All samples were
analyzed with high resolution capillary column gas chromatography with flame ionization detection
(GC/FID) for quantification and selected duplicate samples were analyzed with combined gas
chromatography/Fouriei transform infrared/mass spectrometry (GC/FTIR/MS) for identification of
individual compounds. The results of these analyses are presented.
INTROIH CTION
In order to improve the technical basis for designing effective ozone, control strategies for the
Houston-Galveston arid Beaumont-Port Arthur-Orange aieas of southeast Texas, the Texas Natural
Resource Conservation Commission (TNRCC) has sponsored the Coastal Oxidant Assessment for
Southeast Texas (COAST) proicct. The purpose of the COAST project was to develop a
comprehensive air quality and meteorological data base for southeast Texas which can be used to
enhance the understanding of the relationship between emissions and spatial and temporal
distributions of pollutants so that air quality simulation models and. ultimately, air quality
management strategies can be improved. An important component of the COAST study was the
characterization of the composition and concentrations of the organic precursors of ozone - mainly
r.on-merhane hydrocarbons (NMHC) in the C2-C12 range, collected by the canister sampling method
(U.S. EPA, 1991').
However, in some airsheds the fraction of hydrocarbons with carbon number > CI 2 existing
in the gas piiasc, so-called senu-voiatilc hydrocarbons (SVHC), could be significant. These airsheds
include areas strongly influenced by diescl emissions or other fossil fuel-type emission sources, as is
the case in southeast Texas. Ir has been shown in a recent study conducted in the Fort Mc Henry
(Baltimore, Maryland) and Tusearora (Pennsylvania) Tunnels that the total NMHC concentrations
measured in the tunnels incieased by up to 60% when the concentrations of SVHC in the range CiO
C20 were added to those of volatile C2-C12 hydrocarbons obtained from canister samples (Zielinska
et al., 1993/ 1994'). It has been also shown in the SJVAQS/AUSI'tX study (1989) that canister
samples collected within an oil production area (Kern River Oil Meld, CA) exhibited an unusually
high number of peaks eluiing in the range >C8. However these peaks were not identified or
quantified.
Clearly, a complete analysis of all gas-phase hydrocarbons is necessary in order to determine
the relative importance ot SVHC in relation to traditionally measured gas-phase total NMHC. In
recognition of this need, a limited number of Tenax samples analyzed for C8-C20 hydrocarbons wer
collected during the summer 1993 COAST study, in parallel with canister samples analyzed for C2-
C12 hydrocarbons. In addition to ambient air measurements, a number of Tenax samples were
714
-------
collected in the vicinity ol the main industrial complexes and in an urban tunnel. This paper
describes the preliminary results of Tenax samples analysis.
EXPERIMENTAL M ETHODS
Sampling
Ambient Tenax samples were collected at the Galieria, Clinton and Port Arthur sampling sites
from August 26 to August 30. 1993. The Gallcria site was located in Bcllairc City, in the Houston-
Galveston metropolitan area. The site was surrounded by local streets and the busy 1-610 freeway
was located -210 m east. This was a typical urban site, impacted by motor vehicle emissions. The
Clinton site was located in an industrial suburban Houston aiea with a major refinery plant no more
than I km from the site. It was surrounded by residential streets and the 1-610 freeway was -750 m
away. The Port Arthur sampling site, located in Port Arthur, approximately 60 miles- southeast of
Houston, was situated in a Hal field, ~4(X) m away from Highway 365. It was a rural site, except
tiiar a big refinery (Texaco) and a pulp mill were situated not far away. The samples were collected
during 1-hour sampling periods, starting at 0300, 0700 and 1500 hr, in parallel with canister
sampling. Over a three-day sampling period, 22 Tenax samples were collected (plus 22 duplicate
and -H back up Tenax cartridges).
Source samples were collected during the period September 1 through October 8, 1993.
Motor vehicle exhaust emission samples were collected in the Baytown Tunnel, a motor vehicle
tunnel on Highwav 146 situated under the Houston Ship Channel and connecting Baytown and l.a
Porte. Samples were collected inside the tunnel and, in parallel, in the ventilation building intake
room to account for the background ventilation air. In addition, samples were collected upwind and
downwind of vehicles in the Houston Astrodome parking lot during a major sporting event.
Simultaneous upwind and downwind samples were also collected at a number of industrial clusters.
These included: Exxon Baytown facilities (between Bay Way Drive and Highway 330). AMOCO
Oil (Texas City), Union Carbide (Texas City, adjacent to AMOCO), Dow Texas Operation (Plant B
facility and Oyster ("reek facility in Freeport), and Texaco (Port Arthur). Biogenic emission samples
.verc collected at the major forests around the study area, namely at Brazos Bend State Park, located
,otne 40 miles southwest of Houston (mixed oak/hardwood river bottom forest) and at Sam Houston
National Forest, about 60 miles north of Houston (mostly pine foiest). Approximately 25 source
r'enax samples were collected (not counting duplicate and back-up cartridges).
Ambient and source air samples were collected using glass cartridges filled with Tenax-TA
olid adsorbent. Prior to use, Tenax TA solid adsorbent was cleaned by Soxhlet extraction with
exanc/acctonc mixture (4/1 v/v), packed into Pyrex glass tubes (4 mm l.d. x 15 cm long, each tube
ontained 0.2 g of Tenax) and thermally conditioned for four hours by heating at 3(10 VC under
itrogen purge. After heating, the cartridges were capped tightly using clean Swagelok caps (brass)
•ith graphite/vespei ferrules, and placed immediately in metal containers with activated charcoal on
le bottom and stored in a clean freezer. The cartridges were used for sampling within two weeks
ftcr preparation. The sampling units drew two parallel streams of air at -0.5 I7min per stream,
ince each Tenax sample can be analyzed only once by the thermal desorption method, two parallel
enax samples were always collected. In order to assess the possible breakthrough effect, two Tenax
trtndges in series were employed for each sampling period (hence, four cartridges per unit). After
impling, the Tenax cartridges were capped tightly with Swagelok caps, placed in their metal
>r,tainers with activated charcoal on the bottom, and kept on ice until transported to a laboratory
sezer
tiahsis
Tenax samples were analyzed by the thermal desorption-cryogenic preconcentration method,
llowed by high resolution GC separation and combined Fourier transform infrared/mass
ectrornetric (FTIR/MS) detection (GC/IRD/MSD; Hewlett Packard 5890 II GC with 5979 MS'D and
65B IRD) or flame ionization detection (Hewlett Packard 5890 II GC/FID) of individual
715
-------
hydrocarbons. The Chrompack Thermal Desorption-Cold Trap Injection (TDC'T) unit, which could
be attached to cither the GC/FID or the GC/FTIR/MS system, was used for sample, desoiption and
cryogenic preconcentration. The desorption parameters were as follows: desorption temperature
280CC, held for S min; trapping temperature -140" C; He flow 15 mL/min. A 30-cm piece of fused
silica capillary tubing (0.52 mm id), packed with a small amount of glass wool, was used as a cold
trap. After the cycle of Resorption was completed, the cold trap %va» heated to 280 'C within
seconds and held for 2 min at this temperature. A 60 m (0.32 i.d., 0.25 (im film thickness) DB-1
capillary column (J&W Scientific, Inc.) was used and the chromatographic conditions were as
follows: initial column temperature of 30 "C for 2 mm, followed by programming at 6 rC/min to a
final temperature of 290 '"C and held isothcrmaliy for 5 min.
Several duplicate 'lenax cartridges from each sampling location were analyzed by the
GC71RD/.V1SD technique in order to identify individual hydrocarbons. Identification of individual
components was made based on their retention times, mass spectra, and infrared spectra matching
those of authentic standards. If authentic standards were not available, the National Institute of
Standards and Technology (NIST) muss spectral library (containing over 43,000 mass spectra) and
the U.S. EPA infrared spectral library were used for compound identification. The quantification of
hvdrocarbons collected on all remaining Tenax cartridges was accomplished by the OOTID
technique. For calibration of the GC./FID. a set of standard Tenax cartridges was prepared by
spiking the cartridges with a methanol solution of standard SVHC, prepared from high purity
commercially available C9-C20 aliphatic and aromatic hydrocarbons (Alltech Associates, Inc.).
i ,3,5-trimethylbenzene and n-dodecane were used in the concentration range from -7-8 ng/Tenax up
to 200-300 ng/Tenax. The solvent was then removed with a stream of N. (5 min, 100 ml/min at
room temperature) and the Tenax cartridges were thermally desorbed into the GC system, as
described above. At least three concentrations of each standard compound were employed. Area
response factors per nanogram of compound were calculated for each concentration and each
hydrocarbon and then the response factors were averaged to give one factor for all hydrocarbons
measured. In addition, Tenax cartridges spiked with a mixture of standard paraffinic (in the C9-C2C
range) and aromatic (C4-, C5-, and C6-benzenes) hydrocarbons were periodically analyzed by
GC/FID to verify quantitative recovery of these hydrocarbons from the cartridges.
Identification and quantification of individual species from the GOT ID analyses were based
ou the DRI laboratory calibration table, which contains -200 species. GC/FTD outputs are connects
to a data acquisition system (ChromPerfect, Justice Innovations, Inc., Palo Alto, CA). The software
performs data acquisition, peak integration and identification, hardcopy output, posl-run calculations
calibrations, and user program interfacing. Acquired data arc automatically stored on a hard disk.
Peak integration is generally hand checked for accuracy and an integration output file is generated I
the ChromPerfect software and stored to disk as an ASCII file. This file is imported into a custom
designed data-base management system (running under FoxPro version 2.5, Microsoft Corp.,
Redmond. WA) that is used to confirm peak identifications. This system requires the user to
manually identify 12 or fewer peaks which are then used for a correlation analysis with observed
retention times to compare with the calibration file. The adjusted retention times are used to assigr
peak identifications for all detectable peaks. The retention time, adjustments and peak assignments
arc executed automatically by a subroutine of the program. The ChromPerfe-ct and subsequent
confirmatory peak identifications are then compared and discrepancies are resolved by tlx? analyst
based on peak patterns or confirmatory identification by GC/MS. In the final step, the validated d;
are appended to the master data base. Each sample appears as a record within the data base and is
identified by a unique, sample identification numher, site, date, and time and as a primary, c.ollocati
blank, spiked, or replicate, sample. Typically, over 85% of the detectable C8-C20 hydrocarbon ma
was identified and quantified.
716
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RESULTS AND DISCUSSION
Compound Identification
In order to identify as many individual SVIIC as possible, selected duplicate Tenax samples
from each sampling period and sampling location were analyzed by the CiC/FTIR/MS technique.
From a single analysis, this .system gives three dimensions of data for positive compound
identification: retention times, infrared spectia, and mass spectra. The Fourier transform infrared
technique proved to be very helpful in the identification of non-hydrocarbons, especially oxygenated
compounds, due to the high sensitivity and selectivity of IR spectroscopy to these types of
compounds. For example, in several ambient samples collected in the Clinton and Port Arthur areas,
a number of aliphatic C9-CI0 alcohols were identified, based on their I "MR and mass spectra. In the
source samples collected upwind of Dow Chemical (Oyster Creek facility) a high concentration of
phenol and tert- and see-bulyl phenol derivatives was found. However, the Schenectady Chemical
plant, situated upwind of Dow Chemical, is probably responsible for this chemical presence.
Samples collected in the vicinity of petroleum plants, such as AMOCO and Exxon, showed the
presence of alkyi- (mostly C2-C4) substituted cyclohexanes. These compounds were also found in
Tenax samples collected upwind of Union Carbide. However, the Union Carbide facilities in Texas
City arc adjacent to AMOCO Oil facilities.
Compound Quantification
Tables 1 and 2 show the concentrations of paraffinic, oletinic. aromatic and total
hydrocarbons in the C8 C20 range, for ambient and source Tenax samples, respectively. It can be
seen from Table 1 that the highest ambient concentrations of C8-C20 hydrocarbons were, generally
observed in Clinton, and the lowest ones in Port Arthur. The sample collected in Clinton on August
26 from 0700 to 0800 hr shows an unusually high proportion of paraffinic hydrocarbons, i'his is due
to the presence of a number of C11-CI2 paraffins, which suggests the influence of a nearby refinery.
Tw o morning Clinton samples collected on August 29 (0300-0400 and 0700 0800 hr) show unusually
high concentrations of m/p-xylene, 84 and 159 ppbC, respectively. These high concentrations, not
iccompanied by proportionally high concentrations of ethy!be:i/.cne and o-xylene, cannot be due to
nornr vehicle emissions. In addition, the sample collected a! 0700 to 0800 hr contained a significant
imount of C9-C10 aliphatic alcohols. The same alcohols are also present in a sample collected on
he same day from 1500 to 1600 hi.
The Galleriii samples show the highest concentrations of C8 C20 hydrocarbons in the samples
•ollected from 0700 to 0800 hr, during morning rush-hour traffic. The hydrocarbon pattern is typical
or a site impacted mainly bv motor vehicle emissions.
The highest C8-C20 hydrocarbon concentrations for Port Arthur arc observed in the samples
ollected in the early morning, from 0300 to 0400 and 0700 to 0800 hr. Samples collected or.
vugust 29 from 0300 to 0400 hr, as well as those collected on August 30 from 0300 to 0400 and
700 to 0800 hr, contain the significant amount of C9-CI0 aliphatic alcohols. These samples also
:ow relatively high concentrations of naphthalene, I - ar.d 2-methylnaphthalenes,
imethylnaphthalenes and biphenyl.
In the source samples, the highest concentrations of C8-C20 hydrocarbons were observed in
ic Baytown Tunnel (sec Table 2). reaching nearly 3 ppir.C during peak traffic hours. The lowest
incentrations were recorded for the biogenic emission impacted sites, namely Brazos Bend and Sam
ousron National Forest. Although all Tenax samples collected in these locations show the presence
"biogenic hydrocarbons (mainly a- and fl-pinene, limonene, and sabinene), the obtained
uicentration values are not quantitative. These compounds, particulaily oc-pinene. show significant
eaklhrough during sampling of large volumes of air with Tenax (-30-35 L in our case). Biogenic
'drocarbons, such as a- and B-pinene, and limonene were also observed in most of the Tenax
mples collected in all three ambient air sampling locations.
Tenax samples collected downwind of Exxon (Baytown) and AMOCO Oil (Texas City) show
atively high concentrations of C8-C20 hydrocarbons, especially the samples collected on
717
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September 9 and 28 from 1540 to 1640 and 1725 to 1825 hr, respectively. The proportions of
paraffinic hydrocarbons in these samples in relation to total hydrocarbons arc relatively high. This is
due to the high concentration of n alkanes in the C8-C14 range. All Exxon and AMOCO downwind
srmiples show also the presence of C2 C4 alkyl cycSohexanes.
The. C8-C20 compounds identified in the source samples may prove useful in the
development of emission profiles for these sources. However, due to the very limited number of
Tenax samples collected during this study, it is not possible to develop such profiles at present. The
compositions and concentrations of C8-C20 hydrocarbons found in the individual ambient and
source lenax samples are presented in detail elsewhere (Zielinska et al., 19944).
CONCLUSION
Semivolatilc organic compounds in the C8-C20 range collected by means of Tenax-TA
cartridges during the COAST study in Texas, occur in appreciable concentrations in ambient and
source samples. Some of these compounds may prove useful in the development of emission
profiles for local sources.
a(:kn()\vi,ki)(;i-:mkms
Financial support for this study was provided by the Texas Natural Resource Conservation
Commission. The authors thank Eric Fujita, Desert Research Institute, for helpful discussions.
References
1. U.S. Environmental Protection Agency (1991). "Technical Assistance Document for Sampling
and Analysis of Ozone Precursors. ' EPA/600 8 91/215. U.S. Environmental Protection Agency,
Research Triangle Park, NC.
2. Zielinska, B., Sagebtel, J., Sheetz, L.I I., et al., "Hydrocarbons in the range of C10-C20 emitted
from motor vehicles: diesel versus spark ignition," in Proceedings of the 1993 U.S. EPA/A&WMA
International Symposium on Measurement of Toxic and Related Pollutants, V1P-34; Air & Waste
Management Association, Pittsburgh, 1993; pp. 123-128.
3. Zielinska, B ; Sagebtel. J.C.: Harshfield, G., Gertler, A.W.: Pierson, W.R.; "Volatile organic
compounds up to C20 range emitted from motor vehicles; measurement methods," 1994,
submitted to Atmos. Environ.
>V Zielinska, B , J. Sagebiel, L. Sheetz. G. Harshfield, and E. Uberna (1994). "Tenax Sampling and
Analysis. Final Report." Prepared for Texas Natural Resource Conservation Commission, Austin
TX, by Desert Research Institute, Reno, NV.
718
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Table 1. Summary Table for Ambient Tenax Samples
Sampling
Sampling
Sampling
Total (Cfi C20i in ppbC
date
timo
location
pziraffitiu
olu'ins ;
aromatics hydrocarbons
26-Aug-93
700-800
CLINTON
175.3
5.7
78.7
259.7
29-Aug-93
300-400
CLINTON
40.4
10.4
231.5
282.3
29 Aiig-93
700-800
CLINTON
57.5
9.7
293.6
360.8
29 Ajc-93
1 500-1 GOO
CLINTON
27.4
3 0
81.1
111.6
30-Aug-93
300-400
CLINTON
18.3
13.2
108.5
140.1
30-A-jp-93
700-800
CLINTON
15.0
2.7
103.1
120.8
30-Aug-93
1500-1600
CLINTON
54.7
3.9
108.5
1 67.1
26-Aug-93
700-800
GAUERIA
22.0
5.0
111.8
138.9
26 Aug-93
1 BOO 1600
GALLERIA
11.8
1.7
51.8
65.3
29-Aug-93
300-400
GALLERIA
1C.5
3 0
61.3
74.8
29-Aug-93
1500-1600
GALLERIA
7.1
1.9
35.0
44.1
30-Aug-93
300-400
GALLERIA
1C.9
3.0
46.7
90.6
30-Auo-93
700-800
GALLERIA
43.8
18.3
220.4
282.4
3C Aug 93
1500 1600
GALLERIA
5.9
1.3
25.1
32.2
26-Aug-83
700-800
PORT ARTHUR
9.0
2 9
31.4
43.2
26-Aug-93
1500-1600
PORT ARTHUR
4.2
1.0
7,5
12.6
29-Aug-93
300-400
PORT ARTHUR
13.5
4.8
53.9
7 2.2
29-Aua-93
700-800
PORT ARTHUR
12.6
6.5
67.6
86.7
29 Aug-93
1500 1600
PORT ARTHUR
4.8
0,4
4.3
10.1
30 Aug-93
300-400
PORT ARTHUR
5.9
2.6
24.8
33.2
3C-Aug-93
700-800
PORT ARTHUR
8.2
3.4
44.5
56.1
3C-Aug-93
1500-1600
PORT ARTHUR
3.2
0.7
8 4
12.2
Tebl* 2. Summary Tabla for Source Telia* Samplas
Sampling
Sampling
Sampling
Iota' (C9-C20) in ppbC
rintfl
time
location
penffins
c.'efins aromatics hydrocarbons
21 -Sep-93
700-800
BAYTOWN TUN.
180.1
14.8
2724 2 2919.2
21 -Sep-93
700-800
BAYTOWN TUN. VENT
21.0
3.2
126.2
150,5
24-Sep-93
1800-1900
BAYTOWN TUN.
181.7
13.4
2516.8 2711.8
24-Snp 93
1800-1900
BAYTOWN TUN. VENT
9.9
1.4
21.4
32 7
1 0 Snp-93
1500 1539
BRAZOS REND
5.1
1.9
22.3
29.4
01 Oc* 93
1320-1420
DOW (PLANT BJliW
9 6
2.5
21.5
33.6
OI-Oct-93
1 730 1830
DOW {OYSTER CR.rlJW
33.2
4.4
50.8
88.4
01 0ct-93
1732-1832
DOW (OVSTEft Cft.i-DW
9.8
1.0
19.8
30.b
02-Oc*-93
1445-1600
TEXACO-UW
9.9
1.3
24.3
35.5
02-Oct-93
1445-1600
TEXACO-DW
1 1.6
1.6
27.1
40.4
11-Sop-93
1205-1305
ASTRO DOME-DW
16.3
1.2
66.2
83.7
11-Sap 93
1205-1305
ASTRO DOMF-UW
21.5
6.5
108.2
136.2
30 Sep 93
1130-1230
UNION CARBIDE DW
16."
1.0
38.9
56.6
30 Sop-93
1130 1230
UNION CARBIDE-UW
53.4
4.1
108.1
165.5
28-Sep-93
1415-1515
AMOCO-DW
21.9
2.5
60.3
84.7
28-$ep-93
1415-1515
AMOCO-UW
17.5
3.4
33.0
54.0
30-Sep-93
1615-1715
AMOCO-DW
34.4
3.3
74.4
112.0
28-Sep-93
1725-1825
AMOCO-UW
15.3
3.9
51.9
71.1
28-Sep-93
1725-1825
AMOCO-DW
1 12.3
8.8
194.5
315.6
09-Sep 93
1530-1630
EXXON-UW
11.5
0.4
26.5
33.4
09 Sop-93
1540-1640
EXXON DW
111.3
2.0
168.9
282 2
09 Sop-93
1930 2030
EXXON-UW
21.1
0.8
76.0
97.8
09-Sep-93
1930-2030
EXXON-DW
27.2
10.9
77.6
115.7
04-Sep-93
1350-1460
S. HOUSTON NAT. FOP.
2.4
1.7
3.8
7.9
04-Sep-93
1625-1725
S. HOUSTON NAT. FOR.
3.3
4.1
6.5
14.3
04 Snp-93
1800 1900
S. HOUSTON NAT. FOR.
3.5
7.6
6.0
17.0
DW - Downwind, Up - Upwind
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The Determination of Hazardous Air Pollutants with a
Built-in Pieconcentrator and Capillary GC
Norman Kirshen and Elizabeth Almasi
Varian Chromatography Systems
27(10 Mitchell Drive
Walnut Creek. CA 94598
Under the 1990 Clean Air Act Amendments industries identified as major
sources of hazardous air pollutants must meet Maximum Achievable Control
Technology standards within a certain time frame. The resultant reduction of emissions
is enforced under the Title V permit program. This reduction inav require monitoring
of the source as well as at the fenccline of the facility precursors. Multiple location
monitoring is required during the remediation of certain hazardous waste sites to track
the air pathways ensuring that pollutants arc not transferred outside the site.
Gas Chromatography and Gas Chromatography,'Mass Spectrometry in combination
with air sample rcconceiuratiun is the piimary analytical technique used for
these monitoring requirements since it provides the besl sensitivity and quantitative
reliability. One problem with this approach is the size as well as the complexity of
these preeoncenUatoi/GC systems.
A hazardous air pollutant GC system has been configured with a new built-in
sample prcconcentration trap (SPT) and associated valving capable of preconcentrating
air samples of variable volumes. Since the prccoucentrator is built into the GC, the
system has a small footprint, simple interlacing, and control from one PC. The air
sample is drawn either from a canister or directly from the ambient air through SPT
adsorbct trap. The adsorbent trap is cooled to initial conditions using the option of a
cryo or non-cryo technique, hollowing trapping, the air toxics are quickly desorbed
with the fast heating (40° C/scc) SPT to a wide bore capillary column with detection
by FID. PID, ECD, or a combination of detectors. No column oven cryogenics are-
required.
Optimization of the trapping and chromatographic parameters has been
performed using a '10-14 air standard. The results of these studies and a description of
the integrated system will be presented.
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An Integrated Approach to Parts-per-TriJIion Measurement of
Volatile Organic Compounds in Air
Eric I). Winegar, R.R. Freeman, mid ('.('. ('.rum?
Air Toxics Limited
180 Blue Ravine Road, Suite B
Folsom, CA 95630-4719
The quest for ever lower detection limits continues, with part-per-trillion
(pptv) measurements of volatile organic compounds becoming the latest "Holy Grail"
in air quality measurements. In particular, the 0.1 ppbv level is a recent defacto
benchmark in analytical performance. A unique combination of factors must be
considered in any measurement made at this level. These factors include canister
cleaning and certification, advanced analytical technologies, and adequate quality
assurance. Assuming a 0.1 ppbv detection limit, the canister and sampling system must
be cleaned to at least that level or below. The analytical system must have correctly
derived detection limits, and the usual quality assurance requirements (calibration
using accurate standards, piccision and accuracy, etc.) must be met for this level
while taking into account the usual limitations such as inherent imprecision associated
with each step in the process. Each of these factors alone will not assure success; it is
the combination that provides the requisite analytical accuracy and precision.
High quality ambient air sampling and analysis is the obvious recipient of such
performance goals, especially in light of the current unit risk factors in use for risk
assessment, 'lliis paper will examine some of the factors that must be considered in
order to generate pptv data. Specific measurements of low level concentrations of
volatile organic compounds will be presented using this method, including ambient and
indoor air, and emissions from various consumer products such as textile floor
coverings, computers, and miscellaneous other materials in an environmental chamber.
An integrated experimental approach to the sampling and analysis of pptv
concentration values will be presented.
721
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VOC Quality Control Measurements in the
CASTNet Air Toxics Monitoring Program (CATMP)
Michael G. Winslaw, Matthew M. linotli, and Dwight K Roberts
Analytical Services laboratory
Environmental Science & Engineering, Inc. (FSE)
P.O. Box 1703
Gainesville, Florida 32602
The determination of volatile organic compounds (VOCs) in ambient air with
acceptable precision and accuracy at concentration levels as low as 0.1 ppbV is the
primary analytical requirement of the Environmental Protection Agency's (EPA's)
Clean Air Status and Trends Network (CASTNet) Air Toxics Monitoring Program
(CATMP). The CATMP was established in 1993 by EPA lo reactivate and operate the
Urban Air Toxics Monitoring Program (UATMP). The purpose of the program is to
establish baseline toxics concentrations, develop air emission inventories, and to
identify air toxic sources using chemical mass balance modeling techniques.
Samples arc collected from 15 urban sites in passivated stainless steel canisters
every 12 days and analyzed with a gas chromatograph/mass spectrometer (GC/MS)
operated in the electron impact full-scan mode. 53 target VOCs are determined.
Analytical procedures and instrument operating parameters are described in detail. The
paper focuses on the analytical quality control (OC) measurements which accompany
every batch of samples analyzed. These include the analysis of instrument performance
check standards, calibration standards, NIST reference samples, canister blanks,
replicates, and internal standards/surrogates. Results of QC measurements performed
during 1993 arc presented, including precision and accuracy determinations. Data for
selected VOCs determined in network samples are also presented.
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An Automated GC Technique for Enhanced Detection of Organic Compounds
Monitored Using Passive Organic Vapor Badges
Koc/iy Fung
AtmAA, Inc.
23917 Craftsman Koad
Calabasas, CA 91302
The principle use of organic vapor badges is for monitoting of exposure to
organic compounds in the workplace, where the concentrations of target species are
typically in ppmv to sub-ppmv range. When this passive device is used for monitoring
of organic compounds in ambient air, (he analytical method used must have good
sensitivity and precision to allow the small amount of compounds collected to be
measured. A Hewlett Packard 5840A gas cinematograph with an autosunipler was
configured for two-dimensional gas chromatography with intermediate cryo-trupping to
measure species like benzene, toluene, I'HKC and MHK. The autosamplcr gave high
injection precision. The primary column was used for separating the large solvent peak
from target compounds. Heart-cutting and cryo-focusing allowed target species to be
analyzed with capillary column with good sensitivity. The technique was used ill
several monitoring programs and showed very good precision. Findings
will be presented and discussed.
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Background Monitoring Of Air Toxics
At The Waste Isolation Pilot Plant
Linda Frank-Supka, Chuan-Fu Wu, Robert II. Ix>pe/.
Westinghouse Electric Corporation
Waste Isolation Division
P. O. Box 2078
Carlsbad, New Mexico 88221
Robert A. Zimmer
Harding Lawson Associates
2400 ARCO Tower, 707 Seventeenth Street
Denver, Colorado 80202
ABSTRACT
The Waste Isolation Pilot Plant (WIPP), located southeast of Carlsbad, New Mexico, has
been constructed as a permanent repository for containerized solid or solidified transuranic (TRU)
mixed waste. The repository is constructed in a massive salt bed formation, 2,150 feet below the
surface. The WIPP has been granted a No-Migration Variance by the U.S. Hnvironmental
Protection Agency (EPA) according to the requirements of 40 CFR 268.6.
As part of the variance, a detailed air monitoring program has been developed for the
facility. The purpose of the program is to detect airborne releases of hazardous constituents at the
earliest practicable time. Routine background monitoring for volatile organic compounds (VOCs)
has been performed at WIPP for the last two years. The monitoring program routinely quantifies
airborne concentrations of five VOCs in the ventilation airstream of the underground facility, using
Compendium Method TO-14. This paper describes the monitoring program in-piace at the facility
and presents a summary of the monitoring results for the last two years.
INTRODUCTION
The Waste Isolation Pilot Plant (WIPP) is a research and development facility designed to
demonstrate the safe transport, handling, and disposal of transuranic (TRU) waste resulting from
defense activities and research programs of the United States government. By definition, TRU
waste contains radionuclides with an atomic number greater than 92 (uranium), such as plutonium,
americium, and curium. Approximately 60 percent of the TRU waste is categorized as mixed
waste, because it contains hazardous constituents regulated by the Resource Conservation and
Recovery Act (RCRA). The waste will be placed 2.150 feet below ground in a deep, bedded salt
formation (Figure 1) located approximately 26 miles southeast of Carlsbad, New Mexico.
The WIPP is defined as a land disposal facility under RCRA Section 3()04(k). I-and disposa
includes the placement of hazardous waste in a salt-bed formation. The term placement
encompasses both storage and disposal of waste in a land disposal unit. The land disposal of
hazardous materials is restricted by the provisions of EPA regulation 40 Code of Federal
Regulations (CFR) Part 268'. However, in accordance with 40 CFR 268.6, land disposal facilities
may, by virtue of site characteristics and/or the properties of the waste they will receive, be gran la
a variance from the land disposal restrictions. To be granted a variance, the owner/operator of the
unit must successfully demonstrate "to a reasonable degree of certainty, that there will be no
migration of hazardous constituents from the disposal unit... for as long as the wastes remain
hazardous" [40 CFR 268.6(a)], A no-migration determination (NMD) by the U.S. Environmental
Protection Agency (EPA) allows untreated restricted wastes to be placed in a land disposal unit,
pursuant to the conditions and limitations of the determination.
724
-------
On November 14, 1990, the EPA issued a conditional NMD for the W1PP test phase (55
Federal Register [FR] 47700'), according to the requirements of 40 CFR 268.6. This NMD allows
the DOE to place untreated restricted wastes for experimental uses in the facility and specifies
conditions and limitations of the determination.
WIPP BIN-SCALE TEST
Until October 1993, the WIPP facility was to serve as an experimental pilot plant. Tests
would be performed during this phase to collect, interpret, and refine data necessary for the
performance assessment required by EPA for radioactive waste disposal. Data gathered during this
phase would also be evaluated to determine if any additional measures are necessary to ensure that
no migration of hazardous constituents will occur beyond the unit boundary.
The planned WIPP bin-scale tests involved testing of repackaged TRU waste in specially-
designed, transportable sealed bins after a series of detailed characterization and examination steps.
A bin is a metal box with sampling ports and instrumentation. Each bin would accommodate the
equivalent of four lo six 55-gallon drums of TRU waste.
Bin-scale tests were scheduled to be performed underground during the test phase. The bin-
scale tests were designed to provide information concerning gas production, gas composition, and
gas depletion rates from actual TRU wastes. The waste would be representative of the general TRU
waste inventory.
In October 1993, the DOE announced that the bin-scale tests would not be performed at the
WIPP. Tests involving radioactivity will be performed at other laboratories. Physical and facility
tests are now planned for WIPP while the waste experiments are completed. When the results of all
testing have been obtained and after meeting all regulatory requirements, WIPP will move directly
to the disposal phase.
VOLATILE ORGANIC COMPOUND MONITORING
As part of the WIPP No Migration Variance Petition, a detailed air monitoring program was
developed for the test phase al the facility. This program is intended to fulfill the monitoring
•equirements of 40 CFR 268.6. Presently, there are five volatile organic compound (VOC)
iampling stations installed at the WIPP facility. Four of these sampling stations are defined to be
:ir monitoring stations and use commercially available portable VOC sampling equipment. The fifth
tation, VOC-10, was defined to be a source monitoring station and uses sampling equipment
!eve!oped specifically for the facility.
The sampling and analysis program that was established in anticipation of the bin-scale
xperimental phase, includes provisions for measurements of direct VOC releases to air from the
in-scale experiments (the source monitoring station). Measurements of airborne VOC
oncentrations also were planned for rhe other four locations. These stations (Figure 2) are located
t the top of the facility ventilation exhaust shaft (VOC-1), near the ventilation air intake shaft
i/OC-2), in the Panel I air intake passageway (VOC-8), and in the Panel 1 air outlet passageway
/OC-9). VOC'-10 sampling activities had stopped due to cancellation of the bin-scale tests,
urremly biweekly sampling is being performed at VOC-1, VOC-2, and VOC-8.
Media other than air are not considered viable contaminant transport pathways and are not
onitored under this program. In the NMD, EPA defined migration at WIPP to be releases of
OCs from the repository to the atmosphere at concentrations above health-based levels at the unit
nindary. Annual average concentrations of individual VOCs above background are used for this
termination.
Generator knowledge of the wastes and process by which they arc generated, in addition to
ailable analytical data, indicate that there are five VOCs most commonly present in the wastes,
lese compounds and their established health-based levels are:
Carbon tetrachloride (0.03 micrograms per cubic meter [^g/m1])
Methylene chloride (0.3 fig/m1)
-------
- Trichlorethvlene (TC1I) [0.3 /ig/m3]
- 1,1,1 -Trichloroethane (TCA) [10.000 Mg/m3]
- l,l,2-Trichloro-1.2,2-trif1uoroethane (Freon 113) [30,000 ng/iti']
VOC sampling and analysis are performed at WIPP using guidance in the F.PA Compendium
Method TO-14, Determination of Volatile Organic Compounds (VOCs) in Ambient Air Using
Summa® Passivated Canister Sampling and Gas Chromatographic Analysis3. Integrated 24-hour
samples are collected in six-liter passivated stainless-steel canisters. The VOC samplers are
operated by WIPP facility personnel, and sample analyses are performed by a contract laboratory.
The VOC monitoring program activities are documented annually in a report to the EPA.
Sampling results for a 12 calendar month period ending August 31 are summarized in each annual
report. The monitoring results for the sampler at the facility ventilation exhaust shaft over the
previous two years are described below.
RICSLLTS
figures 3 and 4 presents a frequency distribution of the results of the monitoring program for
one of the air monitoring stations at the facility. This station (VOC-1) is located at the top of the
repository ventilation exhaust shaft. The nominal air flow at this point is approximately 425.000
cubic feet per minute.
The data in Figures 3 and 4 reflect the day-to-day variability in concentrations at the facility
due to ongoing activities and are not due to activities involving TRU mixed waste. The facility is
not yet accepting waste. Figures 3 and 4 also includes the average and maximum concentrations of
each VOC measured over the two-year period. Concentrations less than 0.2 parts per billion by
volume [ppbvl have been estimated by the laboratory based on mass spectral data that indicated the
presence of the compound, but where the results were less than the laboratory reporting limit.
When a particular VOC was not detected in a sample, one-half of the laboratory reporting limit for
Che compound was reported for the sample. This substitution was made so that annual average
concentrations could be calculated as required by the NMD. Because of this substitution, the
calculated annual average concentrations may be overestimated. The laboratory performs method
blank analyses as part of routine sample analysis. Over 100 method blanks were analyzed during
the two-year period. All of the blank results were less than 0.2 ppbv for the five VOC target
compounds.
The lowest value in the frequency distribution represents the sampler cleanliness certification
limit (0.5 ppbv). Measured values above this lower limit demonstrate that elevated concentrations
of three VOCs are present in the facility. These concentrations are attributed to use of various
paints and solvents within the facility for ongoing operations. As shown in the table, TCA
concentrations are highly variable. The highest TCA concentration measured over the two-year
period was 670 ppbv. The highest concentration measured for the other VOCs was 15 ppbv for
Freon 113.
The calculated average concentrations are at least four orders of magnitude lower than the
standards established for the protection of workers. However, the average concentrations for three
of the compounds (carbon tetrachloride, methylene chloride, and TCE) are greater than the health-
based limits established by EPA ir, the NMD. These results show that background concentrations
must be carefully considered in the calculation of annual concentrations for determination of no-
migration for the facility. The past and ongoing monitoring at the facility to establish baseline
variability in and magnitude of measured concentrations will be crucial for determining whether
migration has occurred once waste is received at the facility.
QUALITY CONTROL AND QUALITY ASSURANCE
A number of quality control and quality assurance (QC/QA) activities are performed as pari
of the overall monitoring program. These activities include: sampler certifications, collection of
duplicate samples, duplicate laboratory analyses, evaluation of field and laboratory accuracy, and
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data validation audit1!. A brief discussion of these activities is included below.
Sampler Certifications
All VOC samplers are calibrated and certified after every three months of operation to ensure
cleanliness and reliable sample recovery. Each air monitoring station has a spare sampling system,
allowing one sampler to he recertified while the other is in operation. The sampler flow rate
projected for routine monitoring is used for the entire certification process. The process entails two
steps for each sampler. First, a sample of ultra high purity air is collected in a canister after
passing through the entire sampling system (inlet and sampler) to evaluate sampler cleanliness.
Second, a sample of humidified calibration gas is collected in a canister after passing through the
sampling system to evaluate target compound recovery.
The zero air certification for air samplers requires that the samplers contribute 0.5 ppbv or
less of each target compound detected in the zero air sample. The comparable limit for the source
monitor is 5.0 ppbv. The calibration gas recovery for any individual target compound must be
between 75 and 120 percent, with the additional stipulation lhal the average recovery for all target
compounds must be between 90 and 110 percent. (Note: WIPP sampler cleaning and certification
activities are described in a paper entitled, "Certification of VOC Canister Samplers for Use at the
Waste Isolation Pilot Plant", also presented in this symposium).
Program Precision
Field precision is evaluated from laboratory analysis of duplicate samples collected with the
sampling systems. Relative percent difference (RPD) is calculated for each set of duplicate samples.
The calculated RPDs ranged from -23 to 36 percent over the two-year period, and 88 percent of the
calculated values were within +/- 15 percent.
The contract laboratory reports laboratory precision based on duplicate analyses of individual
samples. Calculated KPDs ranged from -24 to 33 percent with 95 percent of the values between
+/- 15 percent.
Program Accuracy
A procedure has been developed to evaluate method relative accuracy for the sampling
systems. Sampling systems are challenged with an audit gas in the field. Both a matrix spike and a
xmcurrent matrix duplicate sample are collected. The matrix duplicate samples are obtained so that
he accuracy evaluations can be adjusted for background concentrations present in the facility.
\ccuracv evaluations performed over the two-year period have demonstrated an overall range of -13
o 34 percent for the method.
The contract laboratory tracks internal accuracy weekly for five compounds: 1,1-
ichloroethene, benzene, TCA, toluene, and chlorobeiuene. Over the two year period, 98 percent
f the accuracy values have been within 90 to ilO percent.
tograni Completeness
Completeness for the field effort was determined based on the sampling at the ventilation
¦chaust shaft. This station had the only scheduled routine sampling over the entire period. For the
vo-year period 100 percent of the scheduled samples were collected and the field data validated,
ata validation is also routinely performed on the analytical data packages.
ONCLUSION
Concentrations of V(X's measured at the WIPP facility ventilation airstream demonstrate are
ghlv variable for three of the five. VOC target compounds. The measured concentrations at the
:ility are attributed to ongoing facility operational activities and not to any activities involving
{1J mixed waste.
The data obtained to date represent a reasonable database of concentrations that can be used
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for the design of a disposal phase monitoring program.
REFERENCES
1. U. S. Environmental Protection Agency. Land Disposal Restrictions, 40 CFR Part 268,
Code of Federal Regulations, Office of the Federal Register, Washington D. C.
2. Vi. S. Environmental Protection Agency. Conditional No-Migration Determination for the
Department of Energy Waste Isolation Pilot Plant (WIPP), Federal Register, Volume 55, No.
220, November 14, 1990.
3. Winberry W.T.,Jr., Murphy, N.T., and Riggan, R.M.; Methods for Determination of Toxic
Organic Compounds in Air EPA Methods, Noyes Data Corporation: Park Ridge. NJ, 1990:
pp 467-583.
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;.irr->
<:5«sss<;. -
Figure !. Schenulic of flu? Wll'l1 Repository
:^- .
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SUTTON VOC-IO
STATION VOC-O—
I
DETAIL
STATION VOC-1
l—L'.
_i_
h
STATION VOC-2
THIS IHUSIRAT'OM FOR
INfuRVAT OH PURPOSES ONLY
Figure ?. VOO Monitoring Station l.ncal ions
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NUMBER OF TIMES FOUND
-58118
a
Ms
4
Kf Z
MjI
9
li
a
p1^
02
j& D.
Undcr 0.8
r
16
4.0 8 0
CONCENTRATION,
fS CH2CL2 SO.18)
E3 CCL< so.ii)
LU TCC (0.10)
2
£3.
Ov#r es
Figure 3. VOC Monitoring Data Summary
Frequency Distribution 1991-1992 Data
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NUMBER OF TIMES FOUND
AVQ CONC. (p p bv )
\
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Experience in Establishing
Portsmouth Photochemical Assessment Monitoring Station
lhab H. Faiag, Chunming Qi
Chemical Engineering Dept, University of New Hampshire, Durham, NH 03824-3591
phone: 603-862 2313, Fax: 603-862-3747, e_mail: Ihabunh.edu
Dennis R. Lunderville, Thomas M Noel, Paul A. Sanborn
NH Department of Environmental Services. Air Resources Division, 64 North Main Street,
Concord, NH 03302-2033, phone: 603-271-1370; Fax: 603-271-1181
Abstract
The 1990 Clean Air Act Amendments (C.'AAA) stipulate that tropospheric ozone non-
attainment areas with "serious" or higher classification must implement a network of
Photochemical Assessment Monitoring Stations (PAMS) to quantify and speciate volatile
organic compounds (VOCs) considered lo be one of the prime precursors of tropospheric or
ground-level ozone. Data that will be gathered will include ozone, nitrogen oxides, VOCs,
carbonyls, and meteorological parameters. This paper describes the. approach used by the NH
Department of Environmental Services (DFS) to implement this monitoring program.
1 - Background
Ozone is the primary component of smog which is produced during hot summer weather
by the chemical reaction in the. atmosphere of precursor pollutants from many sources. These
pollutants include nitrogen oxides (NO,) and volatile organic compounds (hydrocarbons) such
as gasoline, chemical solvents, products of combustion ar.d some consumer products. These
pollutants emanate from many sources, including smokestacks, automobiles, industrial process
vents, painting and metal parts cleaning operations. Ultraviolet solar radiation promotes
reactions in the atmosphere between the various pollutants resulting in free radicals of oxygen
which lead to the formation of tropospheric ozone.
It is not uncommon for these pollutants to be transported great distances by the wind.
Tropospheric ozone levels may be significantly higher many miles downwind of the sources
of the pollutants as a result of this transport. Based on the 1990 CAAA, the United States
Environmental Protection Agency (EPA) and the states have identified ozone non-attainment
areas. These, areas are categorized into one of five classes based on ambient monitoring data.
These non attainment classes and the corresponding ppb of ozone are: marginal (121-137),
moderate (138-159), serious (160-179), severe (180-189), ar:d extreme (190-280).
Those areas of the U.S. which arc classified as being in the serious" or higher category
of ozone non-attainment must cotne into attainment of the National Ambient Air Quality
Standards (NAAQS) for ozone by the year 1999. Tiiese areas must also implement a PAMS
program for certain volatile organic compounds which arc suspected of contributing to the
elevated levels of tropospheric ozone. EPA's immediate task is to collect a large volume of
air monitoring data. The data will be used to evaluate, and if need be. redefine acceptable
levels of those compounds determined to be precursors of tropospheric oz.one.
Tropospheric ozone has deleterious effects on humar, and animal health and damages
sensitive plant species. EPA's primary goal in implementing the PAMS program is to
achieve the primary health standards for ozone in a cost-effective manner. Strategies have
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been developed to reduce ground-level ozone. These strategies include the use of
reformulated gasoline, the use of vapor recovery systems at gasoline stations, motor vehicle
inspection and maintenance (I/M) programs and additional controls on industrial processes
and power plants. Continuous monitoring of ozone precursors is necessary to assess the
impact of these strategics.
This paper discusses the progress that has been made by the State of New Hampshire in
implementing the. monitoring requirements of the OAAA. Specifically, we will review our
experience with the continuous gas chromatograph (GC.) being used to monitor VOCs on an
hourly basis at the, air monitoring station downwind of Portsmouth, NH in Kittery. ME.
2 - Siting Consideration
The federal regulations for PAMS (CFR, 1993) require that as many as four different site
types be established around the metropolitan statistical area/ consolidated metropolitan
statistical area (MSA/CMSA) that has been classified as "serious'', "severe", or "extreme" for
ozone non-attainment. The number of site types required is based on the population of the
MSA/CMSA. The Portsmouth-Dove.r-Rochester MSA/CMSA has heen classified as "serious"
for ozone non-attainment. Based on population, NH must install two enhanced ozone
monitoring stations in the Portsmouth area, one upwind of the central business district (CRD)
and one downwind of the CBD. The first site type which must be installed is designated as
"Type 2", This Type 2 site is expected to be the point at which the highest levels of volatile
organic compounds being emitted to the atmosphere from the CBD of the primary site in the
MSA/CMSA will be monitored.
Portsmouth has been designated as the primary city in the MSA/CMSA and the
monitoring network is being designed around it. The site of maximum ozone precursor
impact for the city of Portsmouth has been determined to occur at a point in Kittery, Maine,
about two miles northeast of the central business district of Portsmouth.
It is expected that the site will "sec" VOCs and NO, from motor vehicle traffic in the
CBD and on 1-95, industrial and commercial sources, and the emissions from two fossil
fueled power plants located upwind.
3 - Equipment Housing
The Nil Type 2 PAMS is intended to be an on-line, in-the-field laboratory u> continually
monitor VOC ozone precursors, ozone, nitrogen oxides, carbonyls and numerous
meteorological parameters. The equipment will be housed in an 8' x 16' field office trailer
which will be temperature controlled (6jT-86rF) and have counter space designed specifically
for this monitoring application. Meteorological instrumentation will be located atop a ten
meter aluminum tower located behind the trailer. Data management will be handled by an
on-site PC. with telemetry capabilities through a high speed modem to computers located at
University of New Hampshire in Durham, and at the Air Resources Division in Concord.
Ambient samples will be directed into the trailer by a borosilicate glass manifold equipped
with an induced draft fan to move air through the manifold. Exhaust gases from the ambient
monitors will be. ducted to the outside via the discharge side of the manifold.
The trailer will have two 12.500 Btu/h air conditioners and baseboard heaters for
temperature maintenance. All temperature functions are thermostatically controlled.
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The total cost to construct and install the trailer at the Kiltery site, including the GC
system, the meteorology tower, and the site preparation is estimated to be $171,000.
4 - Planned Ambient Air Sampling
EPA has an extensive list of needs which the PAMS site and data have to fulfill (EPA,
1991). Data on the distribution and concentration of" VOC precursors of ozone and of total
nonmethane organic compounds (TNMOC) are required. The minimum acceptable sampling
frequency for VOCs at a "Type 2" PAMS site are:
Pollutant | Sampling Frequency j What to report ~jj
VOC Eight 3-hour samples every day during the ozone j 55 VOC jj
season. June, July and August. j precursors of jj
1 ozone and jj
j TNMOC |!
Carbon vl
One 24-hour sample every sixth day year-round. This
is done by collecting the sample in a canister.
Samples of 3-hour duration are to be taken 8 times per j Aldehyde !j
day during the same months (June, July and August), i precursors !j
N.H. will attempt to achieve 75% data capture in the 24 hr period. 75% data capture in a
month, and 75% data capture in a quarter. This means that within each 24 hr period a
maximum of 6 hours may be used to do calibration, validation, or blank runs. The sampling
at the N.H. Type 2 PAMS site in Kittery, MH will start in June 1994.
5 - Gas Chromatograph Hardware
The VOC precursors of ozone will be measured continually by a GC equipped with two
flame ionization detectors. While the trailer is being installed and the site prepared, UNII is
working under a contract with the N.H. Air Resources Division to install and test the
hardware and software of the VOC portion of the PAMS. The installed equipment include;
Perkin Elmer (PE) GC 8000 with Taxan Supervision 787, 14" color monitor. The l'H-G<
is equipped with two columns, BP1 (50 m long x 0.22 mm i.d., with 1 micrometer film)
to detect Q to C12 components, and a Porous Layer Open Tubular (PLOT) fused silica
capillary column (50 m long x 0,45 mm o.d., 0.32 mm i.d) to detect C> to Cv
Perkin Elmer automatic thermal desorber (ATD) 400 with air flow controller (Tylan RO-
32), and pumps (Charles llusten pumps CAPEX I.2C)
- Air compressor (CAS T ROA-P106T-AA)
Balston TOC air generator (78-30 TOC), equipped with a gas receiver (Balston 72-007
TOC) and a Perkin Elmer unit, PE-Express (PE N930-1178).
Hydrogen generator (Packard 9200). The output ff pressure is maintained a: 36 psi.
- Perkin Elmer GC-to-computer interface (PE Nelson, analog-to digital, 900 Series
Interface) equipped with a memory buffer for data acquisition and temporary storage.
Helium gas (99.9999% purity) tank with Mathcson 3014C-580 gas regulator. Helium is
the carrier gas. Its flow is adjusted to be 2.4 ml/min. through the PLOT column.
Digital DEC PC 433 dsl.P computer with 14400 bps MNP zoom fax modem.
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The air sample enters the system through a stainless steel line from the glass manifold. It
first enters the ATD 400 at the rate of 15 ml/min and is collected on a cold trap which is
cooled to -30°C by a Peltier cooler. At the end of the sample collection period (40 minutes),
the trap is heated and the sample is transferred to the GC via a heated transfer line. The
sample first passes through the BP1 column to detect the C, and heavier compounds. The
sample is then split, and passed through the PLO T column to detect the C, to C, component.
The 1/8" stainless steel sample line from the glass manifold to the ATD 400 is
approximately one meter in length. A stainless steel 2 micron sintered filter has been placed
in the sample path to prevent particulate material from entering and contaminating the system.
The ATD 400 and GC operate simultaneously. The ATD 400 collects sample air for 40
minutes out of every hour and then transfers the collected sample to the GC lor analysis. The
GC analyzes the sample while the ATD 400 recycles and begins collection of a sample for
the next hour. The cycle is repeated continuously, resulting in 24 hourly samples per day.
The trap which is used in the ATD 400 is dual-bed glass and is packed with 64 mg of
Carbosive Sill and 40 mg of Carbovrap C. The trap is cooled to -3CTC using an electronic
(Peltier) cooler rather than a liquid cryogen, i.e., liquid nitrogen. The concentrated sample is
transferred from the ATD 400 to the GC through a heated fused silica transfer line.
6 - GC Software
The software used for automated GC analysis of ambient air in real time is the PR Nelson
Turbochrom 4.0 package. It has the following capabilities:
- Control supported chromatographs through serial communications.
Acquire analog or digital chromatography data from chromatographs.
Analyze the raw data and report results.
- Automatic acquisition and analysis of data from large batches of samples.
Store the raw data and the calculated results.
- Create methods that define acquisition and analysis parameters.
- Optimize analysis parameters through graphics, then use the improved parameters to
reprocess raw data.
Use graphics application to compare chromatograms.
Communicate with other software applications.
7 - Calibration Standard and Blank
The Pcrkin Elmer GC 8(K)0 can he configured to automatically draw a calibration
standard, or a blank gas, through a separate port. We set the sequence in Turbochrom to do 2
hrs ambient air sampling, followed by 1 hr of sampling of either a blank or a standard. We
are using a Maiitech retention time standard, and ultra pure nitrogen gas, 99.9999% for blank.
Chromatograms were produced by the output function of the Turbochrom software.
8 - Our Observations to Date
1 - Gas Consumption
We arc monitoring the use of Helium gas to determine its consumption, and to time the
replacement of the cylinder. Over a period of two months of continuous running, the Helium
pressure dropped from 2500 psi to 2250 psi.
736
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2 - Halsfon I'OC Gas Generator
The TOC gas generator manual indicates that: 40 minutes are needed to warm up, and 12
hours arc needed to regenerate itself at first start-up. When the unit was shut off, it took us
altogether about 3 hours to he in operation.
3 - Hydrogen Generator
Deionizcd water is needed. Our preliminary experience is that about half of the deionized
water is consumed in a period of one month.
4 - Instruments Manuals
The manuals supplied with the GC have a wealth of information. We found them to be
reasonable, but some sections need more details. For example: "Seal On", "Bus Error" error
messages appeared on the ATD board. These were not found in the manual.
5 - Data Telemetry
We arc using PCanywhere. We had a limited success in accessing remote PCs and moving
files back and forth. We encountered difficulties with Gateway computer running DOS 5.0.
6 - Analysis
We ran analysis of ambient air in the lab. We obtained several peaks. Copies of the
chromatograms of the RP1 and PLOT columns are shown in Figure 1. We have also found no
excess carryover from one analysis to the next.
9 - Plans for the Near Future
These include:
- GC calibration for retention time and for speciation
Continual data acquisition
- Data integration arid analysis
Data telemetry
- Establishing what to be included in a written log
10 - Conclusions
N.H. is making considerable progress towards enhanced monitoring, as specified in the
('AAA of 1990. The plans for a "Type 2" PAMS site are underway. While the Kittery site
is being prepared, the GC system has been assembled at UNH and is being tested for ozone
VOC precursors. Further testing, calibration, data integration and analysis still remain.
References:
1- F.PA (1991), "Technical Assistance document for Sampling and analysis of Ozone
Precursors," F.PA/600-8-91/215, EPA Research Triangle Park (RTP), NC, October.
2- CFR (1993), "Ambient Air Quality Surveillance, Final Rule," Code of Federal
Regulations, Title 40, part 58, Feb. 12, 1993, p. 8473.
737
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me [mm]
Figure 1; Cliromalcip ams of ainhicnt nir. I,eft:tlic PLOT column (Cj-Cs). Right: Ihc BI'l column
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Comparison Studies of Ozone Precursors in Phoenix, Arizona
Carmo Fernandez, Jim Guyinn, and Cheng Peter Lee
Arizona Department of Environmental Quality
Phoenix, AZ 85012
Sucha 1'armar
Atmospheric Analysis & Consulting Company
Ventura, CA 9-KKB
This paper wilt present the comparison of the ozone precursors monitoring
program for Phoenix. Arizona dining 1992 and J993. Specific details and
methodologies will be presented involving collection of air samples and analysis of
spcciatcd measurements for reactive VOC and carbonyl precursors responsible for
ozone formation. Quality control and quality assurance techniques will also be
discussed.
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Implementation of a Risk-Based Air Monitoring Program
Using Integrated and Continuous Air Monitors
Wen-Whai Li, Stephen T. Washburn, and Mary E. Greenhalgh
ENVIRON Corporation, 210 Carnegie Center, Suite 201, Princeton. NJ 08540
abstract
A risk-based air monitoring program was conducted during excavation activities at a
Superfund site. The objectives of the air monitoring program were to (1) ensure that the air
emissions would not adversely impact the health and safety of workers and the surrounding
community; (2) allow excavation activities to proceed without cumbersome engineering controls
that might be required by regulatory agencies in the absence of such an air monitoring program;
(3) evaluate the reliability of continuous VOC and particulate air monitoring equipment in
ensuring compliance with risk-based ambient air criteria; and (4) provide a basis for revising air
monitoring instrumentation and procedures, as necessary.
Personal air samples were collected within the Exclusion Zone using integrated and
continuous air monitors. Ambient air monitoring was conducted at seven stations using nine
integrated air samplers and three continuous air monitors. Three mobile stations were
positioned at the perimeter of the work area, and four permanent stations were installed along
the site boundary. Integrated air samples collected each day were evaluated on the basis of the
site activities, results from the concurrent continuous air monitoring, and the previously
developed risk-based action levels.
This paper presents the methodologies and procedures used in an EPA-approved risk-based
air monitoring program and the subsequent air monitoring results. Development of the risk-
based action levels and the correlation between the integrated and continuous air sampling
results are discussed. The risk-based air monitoring program was found to provide protection
to the workers and nearby residents, and allow for the remediation to performed in a more
cost-effective and efficient manner.
INTRODUCTION
As part of a Superfund site remediation program, excavation was proposed at several
locations where elevated levels of both metals and volatiles had been detected. Although the
site is in a relatively remote area, concerns were expressed by both the state and federal
regulatory agencies regarding the potential adverse health effects associated with emissions
during these excavation activities.
An air monitoring program was established at the site to ensure that emissions during the
limited excavation activities would not pose an unacceptable risk to the off-site community or to
on-site workers. This program consisted of the following main elements:
• The development of risk-based criterion concentrations in off-site air for individual
chemicals of concern;
• Atmospheric dispersion modeling to determine on-site concentrations in air
corresponding to the off-site criterion concentrations; and
• The development of on-site risk-based action levels for a continuous, real-time
monitoring program to ensure that off-site criterion concentrations would not be
exceeded.
The off-site criterion concentrations were developed for specific chemicals of concern.
Based on these criterion concentrations and a site-specific air dispersion analysis, action level*
to be enforced at the work area were developed. Continuous air monitoring was then
performed near the work area to ensure compliance with these on-site action levels. Available
continuous air monitoring equipment was not capable of monitoring specific chemicals of
710
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concern at the site, so action levels were developed for surrogate parameters that could be
measured on a real-time basis. By continuously monitoring for the surrogate parameters, and
periodically measuring for the specific compounds of concern, it was possible to proceed with
excavation activities without major disruption, and without posing unacceptable risks to the
off-site community.
DETERMINATION OF RISK-BASED ACTION LEVELS
Chemicals of Concern and Surrogate Parameters
Based on data from previous waste sampling, the primary chemicals of concern were
identified as arsenic, aniline, and various volatile organic compounds (VOCs), including xylenes
and benzene. Sampling results indicated that the waste contained arsenic at a maximum of
16% (160,000 ppm), with a weighted average of approximately 10%; aniline was detected at a
maximum concentration of approximately 11%. Based on a consideration of concentration,
toxicity and physical/chemical properties, arsenic was determined to be the primary chemical of
concern for potential particulate emissions, while xylenes and benzene were determined to be
the primary concern in vapor emissions.
It was determined that real-time, continuous monitoring of the individual chemicals of
concern was not feasible. Surrogate parameters more amenable to continuous monitoring than
the individual chemicals themselves were therefore identified. Respirable particulate matter
(PM10) was selected as the surrogate parameter for arsenic. Total VOCs was selected as the
surrogate parameter for xylenes and benzene. These surrogates were chosen because the
arsenic would tend to be adsorbed to particulates, while xylenes and benzene would be emitted
almost exclusively as vapors. Aniline could be emitted either in the vapor or particulate phase.
Risk Characterization and Development of Criterion Concentrations
Toxicity Evaluation. EPA-verified toxicity benchmarks, including Reference Doses (RfDs)
for noncarcinogens and Cancer Slope Factors (CSFs) for potential carcinogens, were identified
from EPA's Integrated Risk Information Service (IRIS) data base or from EPA's Health Effects
Assessment Summary TablesInhalation-specific toxicity benchmarks were used when available;
otherwise, oral benchmarks were applied.
Exposure Assessment. Populations at risk of exposure to chemicals emitted during
excavation activities were identified, and reasonable hypothetical scenarios regarding the nature
of their exposures were developed. Direct inhalation of chemicals emitted during excavation
activities was identified as the primary route of exposure. Specific exposure assumptions were
derived based primarily on standard EPA references.
Development of Criterion Concentrations. The term "criterion concentration" was defined
in this study as the chemical concentration in air at the maximum exposure location that results
in a target risk level established for the excavation activities. Criterion concentrations were
developed using risk assessment methodologies outlined by EPA. For noncarcinogens, criterion
:oncentrations correspond to the maximum chemical concentration in off-site air to which an
ndividual may be exposed on a repeated basis without experiencing adverse health effects. For
jotential carcinogens, criterion concentrations in off-site air were derived based on a cancer risk
evel of 1 x 10"*, i.e., that the maximally exposed hypothetical individual would have an
ncremental risk of less than one chance in a million of developing cancer as a result of the
•.xposure. If concentrations based on both carcinogenic and noncarcinogenic effects can be
:stimated, the criterion concentration allowable at the receptor location is the more
onservative of the two concentrations.
Criterion concentrations were first developed for each of the chemicals of primary concern
xylenes, benzene, and arsenic). Criterion concentrations for surrogate parameters (total VOCs
nd PM10) were then calculated based on the assumed composition of the PM1U and VOCs.
74]
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Criterion PM10 concentrations were calculated as 10 times the criterion concentration for
arsenic because respirable particulates associated with excavated waste are assumed to contain
10% arsenic. Criterion VOC concentrations were derived from the criterion concentration
calculated for xylenes and benzene assuming these chemicals would be present in a 6:1 ratio.
On-site, risk-based action levels were derived from criterion concentrations at the receptor by
applying the appropriate correlation factor from the air dispersion modeling, as described
below.
Air Dispersion Modeling
Three sources of potential emissions were identified: the buried waste area; the buried
drum area; and the waste storage building. Dispersion modeling of emissions associated with
excavation and storage was undertaken using the Industrial Source Complex (ISC) model2 for
estimating off-site air concentrations. The area source option of the ISC model was employed
to simulate the effects of emissions from the waste area excavation and buried drum area
excavation. The volume source option was used to simulate the effects of fugitive emissions
from the proposed waste storage building. The selection of the area and volume source models
is consistent with EPA's recommendations on source configuration categorization for Superfund
sources'.
Modeling Parameters. Five-year (1985-1989) continuous hourly surface meteorological data
recorded at a nearby international airport were processed in conjunction with concurrent upper
air data4 to provide consecutive hourly meteorological data for the ISCST modeling. The rural
mode option was chosen in the dispersion modeling because within a 3-km radius around the
source area, less than 20 percent of the land can be described as light-moderate industrial,
compact residential, or commercial using the meteorological land use typing scheme proposed
by Auer5. Major model input parameters are shown in Table 1, and Figure 1 shows the
locations of all individual receptor locations around the site. In addition, a 961-receptor grid
was selected to cover the impact area.
Calculation of Chemical Concentrations in the Environment
Waste Area Excavation. The waste area excavation was designed to be conducted
sequentially. At any given time, only a fraction of the waste area would be disturbed.
Therefore, a time scaling factor, Tj/T, was used to scale the emission rate resulting from
disturbance of the j" fraction of the vault waste, where T, is the time required to excavate
subarea j and T is the total time required for excavating the entire waste area. It was estimated
that the excavation would take place sequentially at three subareas. During each excavation,
only half of the subarea would be disturbed and exposed to the atmosphere, while the other
half would remain undisturbed and covered.
• Annual Average Concentrations in Air. For emissions produced during excavation,
emissions from source j would persist only for a period of time Tj during the whole excavation
time, T. Therefore, the chemical concentration averaged over T would be Tj/T of the air
concentration during excavation. In the current assessment it is assumed that Tj = 1/6 T.
• Time-Varving Emission Rates. Emissions resulting from the waste area excavation
were expected to occur primarily during the day. It was conservatively assumed that excavation
would occur seven days per week between 8:00 a.m. and 6:00 p.m. for a period of six months.
The exposed waste surface would be completely covered at the end of each work day.
Therefore, emissions would occur only during the day and there would be no significant
emissions between 6:00 p.m. and 8:00 a.m. each day.
Buried Drum Area Excavation. Excavation at the buried drum area was expected to be
completed in one month. It was assumed that the whole area would be remediated at the same
time. Therefore, there was no time scaling factor for the source emission rates in the dispersior
modeling. However, the time-varying emission rates were applied because the excavation was
742
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assumed to be conducted 10 hours per day, the same as the work schedule for the waste area
excavation.
Waste Storage. It was assumed that the waste storage piles will continuously emit
chemical vapors. Therefore, no time scaling factors or time-varying emission rates were applied
in the air dispersion modeling.
Estimate of Off-site Concentrations
Off-site Air Concentrations. The ISCST modeling results showed the maximum one-
hour average concentration for the nearest resident, 854 (ng/m3)/(g/s-m2), occurred at a
northern receptor. The results also indicated that the annual average concentration is
approximately 400-fold less than the maximum one-hour average concentration at that location.
The maximum annual average concentration at the nearest receptor resulting from fugitive
emissions from the storage building was found to be 27 fig/m3/(g/sec). For waste storage
buildings, emissions are expected to be confined within the building and discharged to the
atmosphere by the building ventilation system or through doors, windows, and leaks. Therefore,
the work area perimeter air monitoring should be conducted within the building, which can be
best characterized by the concentration at the ventilation outlet. Based on a building
ventilation rate of 10,000 acfm, the average concentration at the ventilation outlet would be
0.212 g/m3/(g/sec).
Correlation Matrices for Dispersion Factors. The dispersion factors estimated from
ISCST air modeling were used to establish correlation factors for exposure concentrations of
various durations at locations of off-site exposed individuals (MEI) and at work area air
monitors, which were located between the sources and the receptors. Based on the correlations
between long-term (annual) MEI concentrations and short-term (1-, 2-, 3-, and 8-hr) work area
concentrations, a set of on-site "action-level concentrations" of various durations at the work
area were established from "criterion concentrations" at the off-site MEI to ensure that activities
under normal operations would not result in unacceptable risks to off-site residents. The
"action-level concentration" is the chemical concentration in air at the work area perimeter that
would result in a criterion concentration at the MEI locations based on the air dispersion
modeling.
FIELD MEASUREMENTS, INSTRUMENTATION AND LABORATORY ANALYTICAL
METHODS
Meteorology Monitoring
Meteorological monitoring was conducted at a MetStation (Climatronic EWS System)
located at the southwest corner of the site, approximately 30 feet inside the fenccline.
Meteorological data (wind speed, wind direction, and temperature) have been recorded
;ontinuously on a strip chart recorder since the MetStation was installed. A commercially
ivailable hygrometer, G. Lufft Model 5804, was added later to record the ambient humidity,
rlumidity monitoring was designed to provide information that could be used to quantify the
mpact of condensing humidity on the continuous PM,0 air monitors for particulates less than
10 iim (PMt0).
'ersonal Air Sampling
Persona] air sampling for arsenic and aniline was conducted twice weekly during waste
xcavation activities. Samples were collected in the breathing zone of the most exposed
individuals for the duration of their activities in the work area.
Sampling was performed using constant flow sample pumps (SKC 224-43XR) equipped with
jrbent sample tubes for aniline (silica gel) or mixed cellulose-ester filter cassettes for arsenic,
i flow rate of approximately 2,000 ml/min was used for arsenic sampling; a flow rate of
pproximately 100 mi/min was used for aniline sampling. A primary standard (Gilian
-------
Instruments Bubble Generator) was used with a collection device in-line to measure the flow
rates before and after sampling.
Samples were analyzed by an American Industrial Hygiene Association-accredited
laboratory. In general, analysis for total arsenic was performed using NIOSH Method 7901
(modified). Analysis for aniline was performed using NIOSH Method 2002.
Work Area Air Monitoring
Work area air monitoring was performed at three mobile stations. A fixed station was
positioned in-line between the specific work area and the most sensitive off-site receptor. The
most sensitive off-site receptor was determined based on site-specific air dispersion modeling
and a health-based risk evaluation, as discussed in the previous sections. A downwind station
was located approximately 50 feet directly downwind of the excavation area. The exact location
of the downwind station was determined each day by the site manager and the air monitoring
operator based on the prevailing wind direction that day. During calm conditions (when the
wind speed was less than 1 m/sec, or 2 mph), the wind direction was determined based on the
prevailing wind direction of previous hours and the previous day. An upwind station was
located approximately 50 feet upwind of the excavation area. Unlike the downwind station, the
location of the upwind station was flexible, the only requirement being that it be located away
from and upwind of the excavation area. These stations remained within the Exclusion Zone
throughout the excavation activities.
Continuous Air Monitoring. Each of the work area stations was equipped with a Thermo
Environmental Instruments Inc. Organic Vapor Monitor (OVM) Model 580B, an M1E Real-
time Aerosol Monitor (RAM-1), a PDL-10 Data Logger for use with the RAM-1, a strip chart
recorder, also for use with the RAM-1, and a heating coil unit for use with the RAM-1 when
the relative humidity was above 70%. Both the OVM and the PDL-10 Data logger were
programmed to average continuous readings over one-hour time intervals.
The OVMs were calibrated at the beginning of each day with 250 ppm span gas, and were
checked with the same span gas at the end of the day to determine if the initial calibration was
accurate and if any drift had occurred during the sampling period. Each RAM-1 was calibrated
at the beginning of each day with a manufacturer-supplied reference scatter. If the relative
humidity was high (approximately & 70%), a heating coil unit was used in each station to
reduce the condensing humidity that might interfere with the RAM-1 readings.
While excavation was underway, the hourly information recorded by the OVMs and Data
Loggers was relayed from the Exclusion Zone to the air monitoring field personnel in the
Support Zone by the Site Health and Safety Officer (SHSO). Thus, air monitoring and health
and safety personnel were always aware of the continuous instrument readings.
Integrated Air Monitoring. Integrated samples for PM10 and VOCs were collected at the
fixed and downwind stations, with duplicate samples in the downwind station. Constant-flow
sample pumps were used in conjunction with cascade impactors in the air monitoring program.
Ambient air was drawn through the cascade impactor at a flow rate of 2,200 ml/min for
approximately 8 hours. The flow rate was calibrated each day prior to sampling and maintained
at 2,200 ±5% ml/min throughout the day. A total volume of approximately 1.0 m3 of air was
passed through the substrates and backup filters, resulting in a detection limit of 0.01 mg/m\
The VOC sampling required one Tenax tube, conditioned by the laboratory, and one SKC
pump, calibrated to a low-flow rate of approximately 25 ml/min. Calibrations were performed
at the beginning and end of each sampling period using a Gilibrator.
When integrated samples were being collected at the work area stations, the SHSO would
check every hour that the SKC pumps were functioning normally and relay the readings on the
rotometers of the high-flow pumps to the field air monitoring operator.
-------
Perimeter Air Monitoring
Perimeter air monitoring consisted of integrated sampling at four stations at the site
fenceline (Figure 1). As with the sampling in the work area, integrated samples were collected
for PM10 and VOCs.
Perimeter air monitoring was performed every day when there were soil/waste disturbance
activities at the site. Five 8-hour air samples (four regular samples and one duplicate sample)
were collected each day. At the end of each day, the air monitoring operator and the SHSO
determined if laboratory analysis of these samples was necessary. Laboratory analysis was
required if the work area air concentrations on that particular day exceeded the action levels;
otherwise, the samples were discarded.
Storage Area Air Monitoring
Continuous monitoring of the air quality in the waste storage area was performed
periodically with an OVM to determine if any volatiles were escaping from the overpacked
drums. Whenever any readings above 2 ppm were observed, Sensidyne detector tubes for
aniline and amines and/or integrated volatile samples were taken to determine if these
contaminants were present in the building.
QUALITY ASSURANCE/QUALITY CONTROL
Quality control was enforced via the standard operating procedures for sample custody.
Sample custody procedures were followed through sample collection, transfer, analysis, and
ultimate disposal. The overall data quality for the air monitoring samples was determined to be
very good. Any data requiring qualification are flagged in the data summary tables. However,
field blanks for ambient volatile organic analyses (EPA Method TOl) showed a significant level
of contamination, as discussed below.
Sample Precision and Accuracy
The largest relative percent difference (RPD) between two detected duplicate PM,„ samples
was found to be 139 percent. The smallest difference was 67 percent. The largest difference
between a detected sample and a nondetect was 0.09 mg/m\ The duplicate differences were
within the range anticipated for co-located ambient samples. Small sample weights were
associated with larger differences but were still within acceptable limits, given the small
magnitude of the measurements.
With only one exception, all arsenic samples and duplicates were nondetect. The RPD for
the one pair for which a comparison was possible was 50 percent. The RPDs for volatile
sample duplicates ranged between 0 and 189 percent. Large differences were frequently
associated with low concentrations and suspected laboratory contaminants.
Completeness
Under normal sampling and analysis conditions, it is expected that only 80 to 85%
completeness may be realistically achieved. By use of backup measurement systems and
sampling efforts, at least 99% completeness was achieved.
Field Blanks
The field blanks associated with the TOl analyses for VOCs showed a significant level of
:ontamination. The contamination probably occurred either between conditioning and shipping
ir during packing and shipping. Benzene, toluene and xylenes, as well as other compounds
ietected during the analyses, are associated with a hydrocarbon fraction, possibly diesel fuel,
vhile styrene may have been introduced during shipping. It was determined that use of
tyrofoam peanuts in the shipping of the Tenax tubes was not acceptable and the practice was
mmediately stopped to prevent potential sample contamination during shipping.
745
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RESULTS AND DISCUSSION
Health and Safety Air Monitoring
Volatile organics and PM1:, readings on real-time monitors in the work area did not exceed
the action levels in place for workers in Level B PPE (the initial level of PPE) at any time
during waste excavation. Results from four of the five integrated arsenic samples were less than
the limit of detection; 8-hour time-weighted average (TWA) concentrations were less than
approximately 5% of the OSHA-PEL for inorganic arsenic of 0.01 mg/m3. These results are
consistent with results from the integrated samples collected at the work area stations during
the same time period; all the work area results were below the detection limit for arsenic. One
personal air sample indicated levels equal to the OSHA-PEL for inorganic arsenic. Results
from integrated samples collected from the fixed and upwind work area stations on the same
day were below the limit of detection for arsenic, while arsenic was detected in the integrated
sample from the downwind work area station at about 0.0005 mg/m3, approximately 25 times
less than the TWA concentration at the excavation.
Aniline results for all samples were less than the limit of detection. Eight-hour TWA
concentrations were less than approximately 3% of the OSHA-PEL of 2 ppm (7.8 mg/m3).
Work Area Air Monitoring
PM„ Air Monitoring. Continuous hourly PM10 concentrations at the work area and the
relative humidity at the site were recorded. The RAM-1 readings were sometimes affected by
the ambient humidity, as discussed below. Integrated air monitoring was conducted on the first
day of intrusion into a new portion of the waste area and on other days when significant
disturbance of the material was expected. Table 2 shows the PMl0 and arsenic concentrations
detected in the air samples. The PM,0 concentrations continued to be low due to well
controlled excavation activities. The arsenic concentrations were less than the detection limit,
except for two samples.
VOC Air Monitoring. Continuous VOC air monitoring took place at the same three work
area stations. Integrated VOC air monitoring was performed concurrent with the PMi0 air
monitoring. Chemical concentrations were consistently found to be below levels of potential
concern.
Perimeter Air Monitoring
PM<» Air Monitoring. Integrated air samples were collected at the four perimeter stations
during the excavation. The samples were analyzed if the work area continuous monitoring
indicated exceedance of action levels, or if any unusual conditioas occurred. Based on the
results of work area air monitoring, none of the perimeter samples required laboratory analysis.
However, one round of samples was analyzed because humidity interference with the RAM-1
readings was severe at the beginning of that day. Nevertheless, the concentration levels
observed from all perimeter stations were extremely low and consistent with the regional
background concentrations, indicating that the disturbances caused by the excavation activities
generated relatively insignificant amounts of dust.
VOC Air Monitoring. VOC samples were collected concurrent with the collection of PM10
samples. One round of samples was analyzed for volatiles and semi-volatiles for possible
humidity interference with the OVM. Only toluene, benzene, and tetrachloroethene were
detected, and only at levels not believed to pose a significant health risk.
Storage Area Air Monitoring
Continuous VOC Air Monitoring. Continuous monitoring for volatiles in the storage area
was conducted during the excavation. Readings on one particular workday were relatively high,
likely due to excessive vehicular traffic in the building, and offgassing from the recently painted
746
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cement floor. The readings were highest when many vehicles were driving in and out of the
building. Instantaneous readings decreased to almost 0 ppm when the instrument was raised up
to the breathing zone, away from the floor paint.
An OVM left in the storage area overnight gave an average reading of 2.3 ppm for one
night. The next night, one OVM was placed in the same location, and an additional OVM was
placed in the opposite corner of the building. Though these two averaged less than the 2.3 ppm
measured on the previous night, the drum area was checked with Sensidyne detector tubes for
aniline and amines on the next day-, both tubes showed nondetect.
Integrated VOC Air Monitoring. Integrated VOC samples were taken whenever continuous
readings in the storage area indicated the possibility of volatile contaminants escaping from the
overpacked drums. VOCs were found to be comprised primarily of xylenes, ethylbenzene, and
4-methyl-2-pcntanone.
The Impact of Relative Humidity on the RAM-1 Readings
Figure 2 presents all hourly upwind RAM-1 readings in terms of relative humidities. The
PM10 concentrations observed at the upwind station were comparable to the regional
(0.028 mg/m3) and local (0.016 mg/nr from the pre-remediation air monitoring results)
background air concentrations, since the upwind air concentrations remained unaffected by the
downwind excavation/soil disturbance activities. The background concentrations are
represented by four horizontal lines in Figure 2. It is apparent from the figure that the RAM-1
readings were comparable to the background air concentrations when the relative humidity was
less than 65%. As shown, the RAM-1 readings appeared to be high (in the range of 0.09 to
0.20 mg/m1) at high humidities (i.e., above 65%). It has been observed during humid days with
the heating coil operating that the PM10 concentration detected by RAM-1 dropped from
0.35 mg/m3 to 0.12 mg/m3. Although the heating coil was always turned on when the relative
humidity exceeded 70%, this modification to increase the inlet temperature does not completely
eliminate the humidity interference. A well controlled laboratory environment in which
humidity, temperature, PM10 concentration, and particle size distribution can be carefully
monitored would be required to fully understand and quantify the effect of humidity on the
RAM-1 readings.
Based on the observations from pre-remedial design activities and current air monitoring,
the RAM-1 functions normally at humidities less than 70%. At humidities above 70%, the
RAM-1 tends to overestimate PM10 concentrations in air, but the humidity interference can be
reduced to approximately 0.1 mg/m3 by increasing the inlet temperature. To further offset the
humidity interference, the background concentration or humidity interference (under high
humidity condition) detected from the upwind RAM-1 air monitor was subtracted from the
downwind reading. The differences between air concentrations reported from the upwind and
downwind stations thus represents the ambient air concentration resulting from disturbances of
he work area. The difference in downwind and upwind RAM-1 readings were found to be
;onsistent with the results reported from the integrated air monitoring.
Comparison of Results from Integrated and Continuous Monitors
Table 2 summarizes ambient PM10 air concentrations obtained from the integrated and
:ontinuous air monitors during excavation activities. The eight-hour average PMj0 air
oncentrations were very low because of light excavation activities, high soil moisture content,
nd the conglomerate nature of the vault waste.
All samples except one were below the National Ambient Air Quality Standards for PM10
f 150 Mg/m3 (for 24-hr average) and 50 Mg/m3 (for annual average). This sample taken at the
ownwind station detected an air concentration of 87 Mg/m3 while the duplicate sample, taken
t the same station, detected an air concentration of less than 8 Mg/m3. The difference may
ave been caused by the turbulence-induced concentration fluctuation in the lower layer of the
-------
atmospheric boundary layer, the spontaneous release of a dust puff that bypassed only one
sampler, or laboratory instrumental/operating error in the gravimetric analysis of low
concentrations. It is not unusual to occasionally observe variation of this magnitude in
determining weights of PM10 using gravimetric methods. The concurrent perimeter air
monitoring provided additional air sampling data from different downwind locations. However,
the perimeter air monitoring results for the same day show that the ambient PM10
concentrations were all less than the detection limit of 10 ftg/m\ and the arsenic concentrations
were not greater than 0.3 fig/m', indicating that the off-site residents could not be exposed to
the same arsenic concentration level as the on-site workers (arsenic concentrations of more than
0.3 ng/m3) during that day and would not experience any adverse health impacts, based on the
health-based risk assessment.
Results recorded by the continuous air monitors are consistent with those obtained from the
integrated air monitors except on the days when humidity interference with RAM-1 appeared in
all stations. For those days when integrated samples were collected in the work area and when
the relative humidity was less than 70%, the continuous air monitors, in general, were able to
measure PMl0 concentrations consistent with those measured by the integrated air monitors to
± 0.050 mg/m\ For those days with high relative humidity, all RAM-Is gave false high
readings, in the range of 0.1 to 0.2 mg/m\ regardless of the air monitor locations.
Activity-Specific Action Levels
Arsenic Content in the Airborne Particulates daring Waste Excavation. The average
arsenic concentration detected during waste excavation was less than 0.0028 mg/m'. The
concentration measured at the excavation was rapidly diluted or dispersed in the atmosphere.
By the time the contaminants reached the work area air monitors, the average arsenic
concentration in the air was reduced to less than 0.0003 mg/m'. In addition, at the perimeter
air monitors, no detectable arsenic concentrations were found. The rapid dispersion or
depletion of arsenic contaminants is evident from the air monitoring results obtained on the
"worst" day of excavation. The arsenic concentration observed that day was 0.014 mg/m' at the
excavation, 0.0005 mg/m' at the work area, and less than the detection limit (< 0.0003 mg/m3)
at all perimeter air monitors.
The average arsenic content in the airborne particulates was found to be less than the
initially assumed values at the work area and the site perimeter. It is expected, then, that the
arsenic content would be greatly reduced at the off-site residences.
Based on the above discussions, the initial arsenic content used in the development of site-
specific action levels appears may be overly conservative.
Chemical Content of the VOCs during Waste Excavation. The preliminary VOC action
levels were derived assuming that total VOCs are composed of xylene and benzene in a 6:1
ratio. Based on the concurrent OVM monitoring, the percentage of these chemicals in VOCs
can be quantified as 0.5% benzene and 1.2% xylene.
ACKNOWLEDGMENTS
The authors wish to express their appreciation for the assistance received from
Kirsten Findell, Caroline Czank, Brian Perkins, Arthur Bozza, Tom Fizzano, Mary Enard, and
Jim Roy during the course of this study. The views expressed in this paper are those of the
authors and not necessarily those of ENVIRON Corporation.
REFERENCES
1. U.S. Environmental Protection Agency, Office of Research and Development, Office of
Emergency and Remedial Response; Health effects assessment summary tables, Annual
FY-1991; Washington, D.C, January 1991.
748
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2. Bowers, J.F., Bjorklund, J.R., Cheney, C.S.; Iitdustrial Source Complex (ISC), Dispersion
Model User's Guide, 2d ed. (revised), Volumes 1 and 2, EPA-450/4-88-002a and -002b; U.S.
Environmental Protection Agency: Research Triangle Park, 1987.
3. Roffman, A., Stoner, R.; Air/Superfiind National Technical Guidance Study Series,
Volume IV - Procedures for Dispersion Modeling and Air Monitoring for Superfund Air
Pathway Analysis, EPA-450/1-89-004; U.S. Environmental Protection Agencv, Research
Triangle Park, 1989.
4. U.S. Environmental Protection Agency, Modeling Support Section, Research Analysis
Support Branch; Meteorological data system; Research Triangle Park, 1987.
5. Auer, A.H.. Jr. Journal of Applied Meteorology. 1978 J 7, 636-643.
TABLE 1
ISC Model Input Parameters
Parameter
Waste Area
Excavation
Buried Drum
Area Excavation
Storage Building
Source Type
Area
Area
Volume
Emission Rate (g/s-m2 for
area source, g/s for volume
source)
1.0
1.0
1.0
Source Area (m2)
937.5
231
-
Ambient Air Temperature (K)
293
293
293
Flagpole Receptor Height (m)
0
0
0
Terrain Elevation (m)
Yes
Yes
Yes
Urban/Rural Option
Rural
Rural
Rural
Building Downwash
No
No
Implicit
Initial Lateral Dispersion (m)
~
10.6
Initial Vertical Dispersion (m)
_<¦>
-
4.2
Note:
(l) Automatically determined by the ISC model.
749
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TABLE 2
Summary of Daily Work Area PM1# Air Monitoring Results
Date
Average KAM-1 Heading
(mg/m1)
Integrated Air Sample
(mg/m5)
Upwind
Station
Fixed
Station
0.054
Downwind
Station
0.060*
PMm
Arsenic
Upwind
Station
Fixed
Station
0.009
Downwind
Station
0.020
0.020
Upwind
Station
Fixed
Station
Downwind
Station
Humidity
(%)
1-6-93
0.090
<0.0009
<0.0009
<0.0009
**
1 11-93
0.011
0.043
0.104
0.020
0050
0009
<0.0003
<0.0003
<0.0003
»*
1-27-93
0.053
0.053
0.035
<0.01
0.01
<0.01
<0.0003
<0.0003
<0.0003
63%
1-28-93
0.041
0.041
0.047
<0.01
0.05
0.01
<0.0003
<0.0003
<0.0003
43%
2-3-93
0.019
0.019
0.023
<0.009
<0.01
0.020
<0.0003
<0.0003
<0.0003
35%
2-8-93
0.095
0.072
0.076
<0.008
<0.008
<0.008
0.087
<0.0002
<0.0002
0.0003
0.0005
61%
Average
0.052
0.047
0.058
<0.008
<0.011
0.025
<0.0002
<0.0004
<0.0004
Notes:
* Value estimated from strip chart.
** Hygrometer not available.
M.-MKSrW'M.PA/UMAKIvWSl
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PROPERTY BOUNDARY
BUILDING OUTLINE
FFNCE
® ON-SITE METEOROLOGICAL TOWER
O AW MONITORING STATION
NOTE; ALL AIR MONITORS ARE LOCATED APPROXIMATELY 6 FEET ABOVE THE GROUND SURFACE
FIGURE 1 : SITE SKETCH
REGIONAL BACKGROUND 1: 0.C31 mg/m1
REGIONAL BACKGROUND 2 : 0.027 mg/m3
REGIONAL BACKGROUND 3 : 0.026 mg/m3
(-SITE SPECIFIC BACKGROUND : 0.016 mg/m=
¦ . ¦
-
•_ r _l ¦ _ ______
20 40 60 80 100
RELATIVE HUMIDITY , %
FIGURE 2 : RAM-1 READING VERSUS RELATIVE HUMIDITY
751
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A Two Channel, 16-Position Canister Field Sampler for
Improved Performance and Quality Assurance
O il. Cardin mid J. I . Deschems
Entceh laboratory Automation
950 Enchanted Way #101
Simi Valley, CA 93065
Current automated field samplers used to sequentially collect whole air into
multiple SUMMA canisters contain many deficiencies that add suspicion to data
quality. Mechanical mass flow controllers used have been shown to have temperature
dependent flow rales resulting in different flow rates during day and night operation.
With the absence of dynamic, on-line pressure measuring devices, canisters thai have
leaked since being evacuated in the laboratory would be analyzed with data reported
without question. In addition, the lack of data showing whether sample flow into the
canister dropped off before the end of the sampling period due to leak
prepressurization of the canister oi inconsistent sampling flow rates can result in a
sample that may or may not be lepresentative of the local VOC concentration during
the entire requested sampling time.
A new programmable field sampler is presented that records sampling
information for later ictiieval by a Windows based PC. Collected data can include
flow rate into each canister during the entire sampling event, beginning and ending
pressures in the canisters, feedback verification that the correct canister was being
tilled at the correct date and time, and even the optional flow rate of surrogate into the
canisters during sampling. Flow rates are controlled using electronic mass flow
controllers that arc unaffected by changing temperatures and pressures, with the
added luxuiy of being able to record actual rather than theoretical flow rates. The
canister sampler can be set up for collecting samples literally once a minute to once
every week, depending on the mass flow contiollers installed and the size of the
canisters used. Samplers can be chained together so that the next sampler will
commence as soon as the previous sampler has completed all 16 positions. Monitoring
and control of the sampler can be achieve via modem link to improve implementation
efficiency. Data collected during field sampling operations will be presented as well
as a new piocedurc for unattended dilution sampling of high concentration samples
(stack gas, landfill gas, etc.) which keeps target anulytes well below saturation points
for improved stability and recovery from canisters without heating.
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SESSION 17:
AIR POLLUTANTS IN GENERAL
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Intentionally Blank Page
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Temporal Variation of Fine Particle Mass at Two Sites in Mexico City
Paulina Serrano and George Allen
Harvard School of Public Health
Boston, MA
Margarita Castillejos
Universidad Autonoma Mctiopolilana
Xochirnilco, D.F., Mexico
Diane (laid and Frank Speizer
Urigham and Women's Hospital
Boston, MA
Muuricio Hemdndez
Institulo Nacional de Salud Publica
Cuernavaca, Klor., Mexico
Carl Haves and William McDonnell
US EPA
Research Triangle Park. NC
Simultaneous sampling of fine mass (PM,S. using an integrated 24 hour
gravimetric method) and the particle scattering extinction coefficient (h^, using a
heated integrating nephelometcr) were used to estimate continuous fine particle
concentration at two sites in Mexico City. Linear regression analysis of the 24 h
averages of bsp and the PM; 5 integrated samples was done on a seasonal basis. The
coefficients of determination (R;) between these methods ranged from 0,84 to 0.90 for
the different sampling periods.
These data ate the first attempt to describe the diurnal variation of fine mass in
Mexico City. Distinct and different diurnal patterns were observed for both sites. For
the site located near an industrialized area, a sharp peak occurred between 0700 and
0900 hours and a second smaller but broader peak occurred late at night. This site is
characterized by the presence of primary pollutants, with PM|;, annual mean
concentrations exceeding 150^gm'\
The second site is located in a residential area down wind of the industrialized
area, and is characterized by the presence of secondary pollutants with much lower
PM;0 concentrations (annual mean of under 50 '). The diurnal fine mass pattern
at this site had a broad peak between 0900 and 12(Xt hours. On individual days, tine
mass was sometimes highly correlated with ozone.
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Ability of Fixed Monitoring Stations to Represent Commuter's
Exposure to CO Revisited: The Case of Mexico City.
Adrian bernamlez-Kremauntz
Visiting Fellow
Harvard School of Public Health
665 Huntington Av. Blds>. 1-1305
Boston. MA 02115
AKSTHACT
In-vc.hicle concentrations of carbon monoxide (CO) were compared to concurrent
measurements taken at fixed site, monitoring stations (FSM) to assess if the FSM stations can
be used to estimate commuters' exposure to this pollutant. CO concentrations inside private
and public transport vehicles were consistently higher than those measured at FSM stations and
indeed much higher than those reported in previous commuter studies for US cities. Simple-
regression models with considerable predictive power were developed to estimate in-vehicle CO
concentrations using ambient CO concentrations, wind speed and travel speed data for different
vehicle types.
INTRODUCTION
Taking CO measurements inside vehicles oil a continuous basis is expensive and time-
consuming. What has to be developed then, is a functional relationship between the ambient
CO concentrations and the exposure experienced in the commuting micro environments.
The objective of this paper is to evaluate if the FSM stations can be used to estimate
commuters' exposure to CO. Commuter/fixed-site CO concentration ratios and differences will
be calculated and compared with results from previous commuter studies. Finally, a number of
regression models will be fitted for selected transport modes to assess the possibilities of
predicting commuter exposures to CO using the data collected at the fixed site stations.
METHODS
CO concentrations were measured inside public transport vehicles and private cars while
travelling as a passenger along five standardized commuting routes during the morning and
evening rush hours (6:30 to 9:30 and 17:30 to 20:30). Measurements were taken on weekdays
between mid-January and mid-March of 1991, using six OH COBD-l personal exposure
monitors (PHMs) lent bv the US 1 '.PA. The field work design, as well as the results of
comparisons between transport modes, travel times, travel shifts and commuting routes were
described in a previous paperjij.
Mexico City has an automatic network for atmospheric monitoring (RAMA). In 1991, the
RAMA had 25 stations, of which 15 had CO monitors (NDIR technique). The Five fixed-site
stations located nearest to the commuting routes -- within 2 km at the nearest point - were
selected to compare their data with the in-vehicle measurements. These stations are: Insursynle
Taxquena, Merced, Lagiuiilla and Plaleros. On the basis of their specific sitingpi, Fnsiirgentes anc
Taxqueiia are roadside stations, located within 15 m from busy roads and therefore they are
likely to receive strong influence from vehicular emissions of CO. Although Merced station is
also a roadside station, the road iu which is located does not have as much traffic volume and
congestion as in the case of the other two stations. l.agiwiUa station is in a busy area, but is in
quiet back-street. The nearest heavy traffic road is about 100 m away towards the south. Finall
Plaleros is located in a residential area, about 20 m away from a street with very light traffic. /
thorough analysis of the selected stations has been given somewhere eisep).
756
-------
RESISTS
Ambient CO
As shown in Tabic 1, ambient CO concentrations during the study period were verv high. The
five selected stations reported exceedences to the Mexican and l.'S S-h standards for CO (11
ppm and 9 ppm respectively), [t should be noted that, during the same period, the 9 ppm
standard was exceeded on at least 5 days at 14 of the 15 stations that measure CO in the City.
Figure 1 shows the hourly pattern of CO concentrations measured during the study period at
the selected stations. From 7:00 to 9:00 CO concentrations reach a peak around 12 ppm.
Concentrations then fall to values between 6-7 ppm approximately and remain relatively stable
around this level from 12:00 to 19:00. From 20:00 ambient CO concentrations build up again,
reaching another peak from 21.00 to 23:00. However, this second peak is much smaller than the
morning one. reaching values of 8.0 ppm. The lowest CO concentrations of the day were
registered between 3:00 and 5:00, but even at this time, mean ambient CO concentrations were
still as high as 5 ppm. 'I his characteristic hourly cycle of CO concentrations may be partially
explained by changes in the wind speed during the day. Hie secondary y axis of Figure 1 shows
the hourly average wind speed during the same period. This graph suggests that the peak of
ambient CO concentrations is reached when two factors coincide: the lowest wind speed and the
heaviest traffic of the day.
CO hourly averages from the five stations were extracted and processed to identify the
records for each commuting monitoring day. These data were used to calculate a morning
(06:00 to 9:00 inclusive) and evening (17:00 to 20:00 inclusive) average of one-hour values for
each station. The averaging periods were selected to correspond with the measurement of in-
vehiele CO concentrations. The average ambient CO concentrations during commuters' rush
hours (combining morning and evening) by station were: Lagimilla 7.1 ppm; Plateros 9.1 ppm:
Merd'cl 9.6 ppm: Inmrgentes 9.9: and laxqwnn 11.0 ppm. On the average, the morning values
were 54% higher than the evening ones. The morning/evening ratios for each station were as
follows: Insnrgenies 1.2, both l,a%unilla and Merced 1.6. Plateros 1.8. and Taxqiwm 1.5.
In-vehicle CO
Significant differences in CO concentrations were found between different transport modes.
The highest CO concentrations were found inside autos and taxis colecthai (both 9 seater
"combi" van and 22-seater minibus), while metro trains, trolleys and buses had lower
concentrations. In general, CO concentrations during the morning rush hour were higher than
during the evening. Table 2 shows a summary of CO concentrations by transport mode. A
complete analysis of results is provided in a previous paperti|.
In-vehicle/Ambient CO Ratios and Differences
The daily shift average CO concentration (by route and transport mode) was calculated from
the commuter trips and then matched to the concurrent ambient concentrations (using the
average of the five selected stations). Since the ill-vehicle concentrations for all transport modes
were always larger than the concurrent ambient concentrations, the differences between them
are always positive and the ratios are always greater than one.
Table 3 shows the differences and ratios between commuter and ambient concentrations by
:ransport mode. On the average, commuters' exposure at rush hour was increased above
jinbient CO levels by 42 ppm in autos: 41 ppm in combi: 36 pptn in minibus: 21 ppm in bus: 17
^pm in trolley and 11 ppm in the metro. The magnitude of these values is much larger than the
:orresponding values for other cities studied before. For instance. Holland reported that
ommuting by automobile increased ambient exposures by an average of 3 ppm in Phoenix, 5
>pm in Denver, and 10 ppm in Los AngelesH!- In Washington D.O. commuters increased their
•xposures above ambient CO levels by 7-12 ppm in automobile, 2 6 ppm in buses and 0 3 ppm
-------
in rail veliicles|5). It must be noticed that the Washington study included interstate, highway and
arterial routes, while the one tor Mexico City was conducted mainly on arterial routes.
On the average, the in vehicle/ambient ratios by transport mode were found to be as follows:
auto. 5.2; combi. 5.2: minibus, 4.3; bus, 3.1; trolley 3.0; and metro, 2.2. When findings from
other commuter studies are reviewed, one finds that some of the reported commuter/fixed site
ratios for automobile are also very high. In Los Angeles, the ratio was found to be 3.9[si, in
Boston 2.2 (calculated from ref. [7>), 3.9 in Raleigh[S| and 5.0 in Washington D.C. (calculated
from ref. j5i). However, care must be exercised when comparing these data since the commuting
routes and the reference fixed-site stations selected in every study may have completely
different characteristics.
Regression models
J"he in-vehicle CO concentration data were matched with the ambient CO data from each of
the five selected stations. This was to detect the station with the highest correlation with the in-
vehicle CO concentrations for each transport mode. For simplicity, only the station with the
strongest association with commuters' exposures was used for model building: Plateros station
for the metro and bur, models, and Insurgentes station for the 3uto and minibus models. A
forward stepwise regression method was used (SYSTAT package) to develop models for
prediction of commuters' exposures to CO. Data were arranged in a matrix, matching the in-
vehiclc concentration (time weighted average lor every available trip) with the following
potential predictors:
• FSM = (bncurrent ambient CO concentration (in ppm).
• WSP = Concurrent wind speed measured at the centre of the city (in us1).
• TMP = Concurrent temperature measured at the centre of the city (in Celsius degrees).
• SPD = Average speed for the trip measured in km h
• RUT = Variable indicating the number of the commuting route (1-5).
Table 4 summarizes the resulting regression models. The ambient CO concentration variable
was always entered first into the regression model. Once this variable was in the model, the
decisions on which predictor should next enter the model were based on the following standard
criteria^1: the variable with the largest partial correlation coefficient entered the model first,
and then, an additional term was included only if: a) the F-statistic for the increment in R2 was
significant (p-valuc <.05); and b) the regression (beta) coefficients for all variables in the modi
were significantly different from zero (t-statistic <.05). Additionally, care was taken to prevent
the development of models with serious multicollinearity among the predictors.
The resulting models otter a good combination of the available variables lor prediction of th
commuters' exposures under the circumstances described in this research (during the winter
period, for the specific routes and at the rush hours). All the models have a iairly good
predictive power, explaining between -19% and 71% of the variability in the exposure
experienced by commuters.
DISCUSSION.
As pointed by Cortese and Spengler in their seminal workpi, "the difference between person
exposure and fixed location readings is. in part, caused by the fact that commuters are much
closer To major sources of CO than are the fixed location monitors". In the MA MO. the effect
of transport mode on the relative magnitude of differences and ratios between commuter and
ambient measurements, confirms that commuters' exposures depend strongly on the mode of
travelii],
11)e fact that different monitoring stations and different variables proved to be more useful
predictors for a particular travel mode raises two questions. Firstly, what station or stations
758
-------
should be used for comparison and prediction of commuters' exposure to CO; and secondly,
why do some transport modes seem to be more sensitive to variables such as wind speed or
travel speed than others.
When using ambient data in exposure assessment studies, several monitoring stations should
be evaluated to find out the most .suitable station or group of stations for the specific purposes
of the research, e.g. the estimation of CO exposures in a particular microenvironment (indoors
residential, indoors office, outdoors near the roads, commuting, etc). In the Mexico City's study,
a background station located in a road with light vehicular traffic (Plaleros station) proved to be
more appropriate to estimate exposure of metro and bus commuters, while a roadside station
surrounded by streets with heavy traffic (hvturgentes station) was the most useful to estimate
exposure of auto and minibus commuters.
Fn the future, the models presented here should be validated to determine their predictive
power in two circumstances: firstly, on additional samples taken under similar conditions: and
secondly, to explore their possible use under different conditions such as sampling at a different
season of the year or on other commuting routes.
CONCLI'SION'S
This paper has raised three main points. Firstly, the fact that e.xcecdcnccs of the ambient air
quality standards for CO arc frequently reported in the MAMC. Secondly, that in Mexico City,
as in US cities studied before, measurements taken at the FSM consistently underestimate the
CO concentrations experienced by commuters at rush hour. T hirdly, that, for commuters of
some public transport modes (e.g. metro, minibus and bus), it is possible to develop predictive
models with a reasonable explanatory power by means of using the appropriate FSM stations
and other variables.
ACKNOWLEDGMENTS
The present study would have not been possible without the support of the Undersecretary
for Ideology (SHDI71¦') in Mexico. In particular I thank the personeel involved in the operation,
maintenance and data processing of the air pollution monitoring network (RAMA). Manv
thanks also to the US EPA tor lending the CO monitors used in this study.
REFERENCES
1. Fernandez-Bremauntz. A.A. and Ashmore. M R. Atmos Environ. 1994. (Forthcoinming).
I. Ott. W.R. J.^uuPcilyJ. Control Assoc. 1977 21, 543-547.
>. Fcmandcz-Bremaunlz. A.A. Commuters' Expasure to Carbon Monoxide in the
Metropolitan Area of Mexico City. PhD Thesis. Imperial College of Science. Technology
and Medicine. London. 1903.
. Holland. D M. nnviroiu Int. 1983 9. 369-37S.
. Flachsbarl. P.O.; Howes. J.E.: Mack. GA.: and Rodcs. C.E. J. Air Pollut. Control Assoc.
1987 22. 135-142.
. Petersen. W.B. and Allen. R. J. Air Pollut. Control Assoc. 1982 32. 826 833.
. Cortese, A.I), and Spengler. J.D. J. Air Pollut. Control Assoc. 1976 26, 1144-1150.
Chan. G; Ozkavnak. II.: Spengler. J.D. and Sheldon. L. Environ. Sci. TechuoL
1991 25:964 972.
Jobson. J.D.: Applied multivariate data analysis. Volume I: Regression and experimental design:
Springer-Verlag: New York. 1991.
759
-------
Fixed-site
Daily maximum 8-h CO concentrations
(in ppm)
Days exceeding
AAQS (percent)
Monitoring
Days'
Min
Max
Mean
S.D.
8h>9
8h>13
Stations
ppm
ppm
Taxijuen a
72
5.6
18.9
11.3
2.8
81.9
20.3
hisiirgcnk's
71
3.5
14.7
9.6
2.4
60.6
9.9
Merced
83
4.9
15.0
9.2
2.0
50.6
8.4
Plate ro s
81
4.5
14.4
8.9
2.2
45.7
6.2
LagiiniHa
60
23
22.4
7.2
3.1
15.0
3.3
Table 1. Daily maximum 8-hour CO concentrations during January-March 1991.
'Number of days with complete data sets.
Transport Mode || Trips
Auto
Combi
Minibus
Bus
Trolley
Metro
» 34
J 35
1
l 170
1 47
! in
Min | 25%
' Median
34.9
48.3
1 57.5
23.2
44.4
! 58.6
17.9
34.8
I 42.7
12.9
24.2
j 30.2
14.8
21.6
I 25.6
12.0
17.5
| 20.6
Table 2. Percentiles of average CO concentrations (ppm) of terminus - to -
terminus commuting trips by transport mode|i|.
Trans port
Difference
Ratio
Mode
Vehicle-FSM < ppm)
Vehicle-FSM
Auto
36.5 47.4
3.0 - 7.0
Combi
28.5 -51.6
3.6 - 7.7
Minibus
22.9 - 49.4
3.4 - 5.6
Bus
14.0 - 26.5
2.5 - 4.0
lrol lev-
15.1 - 19.1
2.5 - 3.5
Metro
9.0 -12.7
1.9 - 2.5
Table 3. Comparison between in-vehicle and ambient CO concentrations.
Range corresponds to means for different routes and shifts.
760
-------
METRO
R =.48 N=63 P. Reg Mode] <.001
COHXP = 13.27 + 0.69 FSM
BUS R =.62 N=113 P. Reg Model <.001
Route ! C'OEXP = 43.-15 + 0.66 PSM - 0.61 SPD - 1.37 WSP
Route 3 COEXP = 46.11 + 0.66 KM - 0.61 SPD - 1.37 WSP
Route 4 COfcXi* = 40.56 + 0.66 FSM - 0.61 SPD - 1.37 WSP
Route 5 COEXP = 41.88 + 0.66 FSM - 0.61 SPD - 1.37 WSP
MINIBUS R!=.G3 N=87 P. Rep, Model <.001
Route 1 CO EXP = 47.37" + 1.17 FSM - 291 WSP
Route 2 COFXP = 46..TO' + 1.17 FSM - 2.91 WSP
Route 3 CO EXP = 51.53" + 1.17 KM - Z91 WSP
Route 4 COEXP = 49.06' + 1.17 FSM - Z91 WSP
ALTO R' = .71 N- 21 P. Reg. Model <.001
Route 1 COEXP = 57.87" + 1.70 FSM - 1.28 SPD"
Route 2 COEXP = 63.28" + 1.70 KM - 1.28 SPD"
Table 4. Regression models by transport mode. All coefficients
are different from zero at the p<.001 level, unless
maiked as follows: * p<.05; ** p<.01.
CO concentration -s- Wind speed
2 4 6 8 10 12 14 16 18 20 22 24
Time of day
Figure 1. Hourly CO concentrations and wind speed in Mexico City
during January-March, 1991 (average of 5 selected stations).
761
-------
Investigation of Spatial and Temporal Pattern of Ozone Concentration
within a Metropolitan Area Using Ozone Passive Sampler
L. J. Sally Liu and Petros Koutrakis
Harvard School of Public Health
Department uf Environmental Health
665 Huntington Avenue
Boston, MA 02115
Irvine Binder
The Gage Research Institute
223 College Street
Toronto. Canada M5T 1R4
The Canadian Research on Exposure Assessment Modeling (CREAM) pilot
studies were conducted during the winter and summer of 1992 in Toronto, Ontario,
Canada. In the pilot studies, personal, indoor, and outdoor samples were collected
using passive ozone (113) samplers. Personal 03 samples were taken from 89
participants from 50 different households. Indoor 03 samples were taken from
participants' homes and work places and a variety of non-residential buildings. The
indoor samplers were located oil a "sampling tree" that included a fan to maintain a
constant air flow, Outdoor O, samples were collected by placing passive samplers
outside participants' homes. Outdoor O, concentrations also were monitored
simultaneously by continuous monitors at the 21 stationary ambient monitoring sites
operated by the Ministry of Unvironmcnl throughout Metropolitan Toronto, Central
Ontario, and Hamilton. Approximately 20 duplicate passive samples per week were
taken for quality control and quality assurance purpuses. Air exchange tale of the
homes were taken weekly using perfluorocarbon tracer gas method. Participants were
asked to complete time-activity diaries throughout the monitoring period.
The performance ot' the passive sampler is evaluated for various weather
conditions and various applications. Spatial variation of outdoor O,
concentrations is examined using standardized scores and analysis of variance
(ANOVA) techniques. Factors affecting O, outdoor spatial variation, indoor U,
concentrations, and personal exposures arc examined. A personal (), exposure
model is developed by using home outdoor, home indoor, work place, and other
microenvironmcntal O- concentrations.
-------
A COMPARISON OF AC II) AEROSOL AND OZONE EXPOSl RE PATTERNS
IN A SUMMERTIME STUDY OF METROPOLITAN PHILADELPHIA
Jed M. Waldman and Chris S-K Liang
fcnvironmental & Occupational Health Sciences Institute (IX)IISI)
Division of Exposure Measurement & Assessment
681 Freluighuysen Road. Piscatawav, NJ 08855
Petros Koutrakis, Helen Suh, and George Allen
Harvard School of Public Health
665 Huntington Avenue, Boston, MA 02115
Robert Burton and William E. Wilson
(IS Environmental Protection Agency (YfD-50)
Atmospheric Research and Exposure Assessment Laboratory
Research Triangle Park. KC 2771 i
ABSTRACT
i study of acid aerosol and ozone exposure patterns was conducted for metropolitan Pliiladelphia
etween June and August 1902 Included in the study design were daily monitoring of particulate strong
adity (PSA), sulfate (S04=) and hourly ozone data (O3) at a citywide network A continuous sulfate
lermal speciarion analyzer at one sire collected hourly concentration data for SO4 aerosol The current
iper presents temporal patterns of continuous measurements for O3 and SO-}= aerosol Both pollutants
id similar daily peak periods in the niid-aftemoon. although the range for O3 was much greater than for
'>4 aerosol The daily peak values were also correlated for the two species during the study period It
ems that many of the same meteorological factors affect the spatial and temporal patterns for these lung
itants Hence, the similarity in exposure patterns for O3 and S()4= aerosol is reason for concern,
garding possible synergism from coincident doses
TKODLCTION
>th O3 and particle strong acidity are harmftil to the lung, and, at levels currently observed in parts of
: U.S., they each appear to cause measurable human health effects To understand whether these two
pollutants may act in concert, it is necessary to determine how their exposure patterns relate
-ausc of its status as a Criteria Pollutant of the NAAQS. O3 data are available for all U S
tropolitan areas and most suburban and rural regions At all sites in the NAMS and SLAMS
works, measurements for O3 are made and stored as hourly averages, 24 hours each day Because the
AQS for O3 is a 1-hour standard, data are usually reported in terms of the maximum daily 1-hour
centration
the other hand, measurements for particle strong acidity (PSA) are not nearly as widespread. The
ority of data on atmospheric levels of acidic particles has been produced in just the past few years
le it is now known that acidic sulfate concentrations (24-h) can be as high as 25 ug m"J in the rural
suburban regions of eastern U.S. and Canada, data are notably limited in and around metropolitan
763
-------
areas*
Particle acidity is found to be singularly associated with sulfate aerosol^ It is observed that sulfate
aerosol occurs at its highest levels in the summertime, associated with many of the same conditions
leading to photochemical smog episodes. The data for PSA show that it is also associated with smog
episodes, although the PSA fraction in sulfate aerosol is highly variable and site specific
Ozone in the troposphere remains a resistant problem in much of the eastern U.S., as well as metropolitan
regions in the rest of North America. In the summertime, elevated levels can occur on a daily basis over
an extensive area. It is becoming clear that some of the same factors which elevate O3 concentrations
also have an influence on sulfate and acid aerosol levels. Day-to-day variability of O3 depends chiefly on
variation in meteorological conditions, such as mixing layer depth and temperature, while PSA levels
further depend on the availability of sulfate precursors (SCb) and their reactions and fate.
In order to determine the possibility of synergistic effects for exposure to O3 and PSA during
photochemical episodes, accurate exposure determinations are needed. In this paper, data for a field
study in metropolitan Philadelphia are presented. Our interest is in the coincident exposure patterns in a
polluted region, where there is a high density of people living and working
METHOD
The field study was conducted in metropolitan
area of Philadelphia from June through
August 1092 A network of nine monitoring
sites had HEADS (Harvard/EPA Annular
Denuder Sampler) to measure acidic aerosol
components (PSA and S04= aerosol); five
sites were collocated with O3 monitors
(Figure 1). In addition, at the Northeast
Airport (N/E site) a CSTS (Continuous
Sulfate Thermal Speciation) monitor was
collocated with HEADS and O3 monitors to
measure hourly sulfate levels through the
study period^.
RESULTS
The summer of 1992 was notable cooler and less polluted than others of record. The average daily ps
O3 among the 7 sampling sites were from 50 to 68 ppb during the study period. The maximum le
observed was 117 ppb at ROX site in August (Table 1). During the months June through August, th
was not a single NAAQS exceedence (>120 ppb for 1 h) at any of the sites, while 10 to 15 exceeds
days are more typical. Likewise, the levels of sulfate and PSA were relatively moderate. The aver
sulfate levels were from 63 to 100 nmole/m^ during the same period. PSA levels were only 10 to 30°/i
corresponding sulfate levels; the average concentration ranged from 9 to 33 nmole/m3 among samp
sites. The PSA fraction in nearby New Jersey for previous summers was 20-40%'*.
Philadrtphl*
Figure 1. Sampling sites for Philadelphia study 1992
764
-------
Table I HEADS measurements and hourly o/onc data in Philadelphia summer 1992.
Mil average (nmoli
'mf)
hourly Ozone, (ppb)
June
Jtih
Auk
Jlilk
Juh
A li t
site
SO.f
H * SOj~
H
S04
' H*
meau
nia\
mean
ma\
mean
ma\
fsi/fc
71
17 S3
77
¦S3
21
68
104
Oil
1 f Hi
61
106
ROX
-
XX
29
83
19
-
-
67
109
58
117
LAB
-
91
23
85
1-1
52
81
85
54
If 10
TP VI'
IS 7g
11
8f>
12
-
-
-
-
5'K):»
-
76
10
7')
9
-
-
-
-
-
-
PBY
64
10 ino
2!
88
14
0(i
101
6-1
107
62
Ill
VAt.
-
VI
V)
81
21
-
-
-
-
-
-
hR]r
-
-
-
-
-
5'i
91
54
92
W
i)7
CAM
-
-
-
-
-
61
89
66
96
64
104
*: inner cii> locations
By calculating the average for each hour of the day during each of the summer months, pictures of the
daily concentration patterns for Oj and SO4 aerosol can be assembled (Figure 2) For O3 the diurnaJ
pattern is well known, with the daily peak occurring in the mid-afternoon and the minimum levels
occurring in the morning rush hours. Ozone starts to build up during the daytime hours —after a dip in
the morning rush hours— from background levels (=20 ppb) up to 50-60 ppb at about 3 pm (EST local
time is I h later EST). Because the O3 and its precursors are transported in the windficld, the time of the
daily peak is later at the downwind sites. Likewise, at locations proximal to vehicular arteries, the release
sf fresh nitric oxide (NO) scavenges O3. The O3 levels at FR1 and LAB sites are 10-20% lower than the
Jistal city sites ( fable 1)
V diurnal pattern, similar to O3 was observed for hourly SO4 T aerosol data. The daily peak occurred in
he mid afternoon, simultaneously with the O3 maximum The dynamic range for Sffy" was only =15
max/min). while for O3, it was 5-6 The peak sulfate levels were only 50% higher than background
:vels while peak O3 was 3009 b higher than background levels. Similar lo the spatial pattern of O3.
slatively lower acidity was found in the inner city locations (Table I) The acidity observed at TEM and
00 sites were up to 70% lower than distal city sites
. monthly summary for 24h JiF.ADS. O3 and continuous SO4 aerosol data with respect to different
me intervals is presented in Figure 3 The correlation between hourly SO^ aerosol and O3 were
cammed for various time intervals, such as hourly 12-16, 16-20 (EST), daytime period and nighttime
;riod. The 12-16 interval represents the peak hours for O3 and SO^j'= aerosol. Our concern about the
>-20 interv al is because it is the period of most likely weekday recreation There are strong correlations
'tween O j and sulfate data for hourly 12-16, 16-20 and daytime data with highest correlation
curred during 12-16 (Table 2) Only nighttime data were not significant correlated
Table 2 Correlation and Regression between Q < (ppb) vs. SO4 aerosol (ng/tn^) at N/E site.
Pearson Corr. Coef
Slope
Intercept
T
r~
hourly
0 36*
1.21
18
0.12
12-16
0.52*
1.26
42
027
16-20
046*
1.06
28
0.21
daytime
0.49*
1.17
33
0.24
Nighttime
NA(p>0.05)
-
-
-
24 h
0.40*
0.73
24
0.16
* p< 0.0001
765
-------
70 r
I
Ozone (ppb)
60
50 ]
'I | 0-._W.FAN
T upper sWerr
kwcffftto-
.,u! '
I
NE airport
30
- }-JJuly 92
\
20 J-fr—
to .i Z-.
A
./
0 i-
10 12 14 16
18
20 22
Sulfate Aerosol (ug/ml)
16 ,
U
^SCi-
i ~ | •jprer«de"
\2 | ~ kM«sWerr
K)]-h^t^r
I
- /-Wi i
TZJ t T
L-fcz-JL
-in—f
6
l
4 i—
NE Airport_ :
July 92
16 18
20
0 2 4 O » 10 12 14
HOIK (FS'F)
Figure 2. Average hourly ozone and sulfate concentration patterns for the Philadelphia Study 1992.
July 1992
n^o.e/ntj
MO - -- -
hsads
C_.t'04-
?r*» \-
' 00 1
m
F . |
V'4 .(/A
W
£. :.
a T fel
0s i.j-1
¦>.') m m. \/a
0y> t&a y>/i
\"A ?//* V'A
OZO.NE
05'4 .
907.
pub
J 80
g2
mk& !
V/A
I Wi i*0
10%' '' |
l.„
v
0 K0SVJ c
i i i
4>. Ay /_•> /6-
Q> t .'c
Figure 3 Concentration profile for IIKADS, Continuous Sulfate and Ozone data.
A regression analysis was conducted for CSTS SO4 (average for 24 hourly values) versus HE A
S04; (24-h integrated samples). This indicates an excellent agreement with a slope of 0.96±0.06, r-
766
-------
0.80 and a positive intercept of 34 nniole/m-'. The positive intercept is due to the non-volatile sulfate
aerosols which HEADS dose not analyze collect '. PSA and SO4" aerosol data for HEADS were also
highly correlated (p< 0 0001, R~=0 82). and the average ratio of acidity to sulfate was 0.27+0 13.
fable v C'oirelation analysis among timnh (cmperatuti'. o/onc ;ind sulfate dul.i. 199?
Hourly data Dailv maximum data
Temp
O,
Temp
O,
Oi
0.000J*
0.72""
O,
0.0O0I
0.62
Sulfate
0.0001
0.49
0.0001
0.36
Sulfate
0.0001
0.59
0.0001
0.50
* Pearson correlation probability
**. r-square
iince O 5 and sulfate are products of photochemical reactions and both demonstrate strong diurnal
lattern, we have investigated the relationships among temperature, O3 and SO4 aerosol levels during
he summer months study period Daily average and daily maximum levels were examined for correlation
nd regression relationships There are strong correlations among temperature, O3 and continuous
ulfate data for both daily average data and daily maximum data (Table 3). Because O3 and SO4"
erosol levels in the atmosphere came from different origin and photochemical reactions, these high
orrelations indicates temperature is an independent variable which enhances the co-variance between O3
nd SC>4= aerosol levels, which positive slopes when pollutant concentrations are plotted against
:mperature
ISOLISSfONS
lie O3 concentrations observed at ground level are a combination of physical and chemical reactions,
unrig the daytime, O3 is generated through photochemical reactions and influx from air aloft, the rate of
3 formation exceeds the losses, such as chemical reactions or deposition The levels of O3 attained
pends on the availability of precursor, such as NOx, and solar radiation as well as the surface level
/ersion height. The O3 levels observed at N/E site indicates a 3 times higher than background levels
ring the daytime period At night, photochemical reactions cease and the influx from air aloft is
enched due to a shallower mixing layer after the sun goes down' Sulfate levels follow a the similar
ttern as O3 The generation of sulfate not only depends the levels of its precursor (SO2). but also
liability of oxidant, such as O3 and hydroxy! radical, in the atmosphere to complete its photochemical
ictions. Its format rate is lower than the O3 Our observation for Philadelphia was that sulfate only
reased 40% above its "background" level At night, sulfate has lower deposition and loss rate than
, therefore retains most of its daytime level. This phenomenon was evident in our previous study
ere continuous 12-h sulfate sampling data showed a significant auto-correlation from daytime samples
following nighttime samples'1*. Due to lower depletion at night and more complicated photochemical
chanism, sulfate showed a less apparent diurnal pattern as O3 dose.
1 diurnal patterns for O3 and sulfate aerosols are similar and the peak levels occur in the middle
¦moon This similar patterns of concentration profile will have an important impact on human
osure and associated health outcomes This is especially true for exposure to pollutants which may
767
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induce ail synergistic adverse health effects such as O3 and acid aerosols In addition, the acid fraction
was found higher during the daytime period than nighttime period^. It is putative that higher acid
fraction may occur during the peak hours of O3. Therefore, more human exposure assessment should
pay attention on short term (2-4 hours) co-exposure to O3 and acid aerosols
CONCLUSIONS:
There was a consistent diurnal pattern for O3 among the Philadelphia metropolitan sampling sites: lower
peak values were found in the city center The peak hour was between 12 and 16 (EST). A similar
diurnal pattern was observed for hourly S04= aerosol data with peak levels occurred simultaneously with
O3 peak levels The correlation for peak periods between O3 and S04= aerosol was found to be
significant. Nevertheless, the peak exposure interval was more narrow for O3 than S04=. Since
exposure to O3 is simultaneous with PSA, they may have synergistic adverse health effects. It is reasor
for concern about co-exposure to O3 and acid aerosols during summer air pollution episodes.
ACKNOWLEDGEMENTS
We are grateful to the City of Philadelphia - Air management Laboratory and to the New Jerse
Department of Environmental Protection & Energy for their cooperation and assistance The informatio
in this document has been funded wholly or in part by the United States Environmental Protectio
Agency under Cooperative Agreements to Harvard University (CR-812050) and to EOHSl (CP
819846) It has been subject to the Agency's peer and administrative review, and it has been approve
for publication as an EPA document. Mention of trade names or commercial products does m
constitute endorsement or recommendation for use
REFERENCES
1 Lioy, P.J. and Waldman, JM, "Acidic Sulfate Aerosols: Characterization and Exposur
Enviro mnem al HealthPersgect ives, Vol 79, pp 15-34, (1989).
•*- U S Environmental Protection Agency An Acid Aerosol Issue Paper: Health Effects a
Aerornetrics. tLPA-600/8-88-0051''. Environmental Criteria and Assessment Office, Research Triam
Park, NC. 27711, (1989)
3 Allen G. and Koutrakis P. "Development and Validation of a Model for Predicting Short Term Ai
Aerosol Concentrations from the HSPH Continuous Sulfate/ThTmal Speciation Monitor." Present
at the 1992 EPA/A&WMA Symposium on "Measurement of Toxic and Related Air Pollutants
Durham, NC, May 3-8. (1992)."
4 Liang, C S.K. "Spanning from Regional to Microenvironmental Scales of Exposures to A
Aerosols." Dissertation, Rutgers Univcrsity-UMDNJ Robert Wood Johnson Medical School, (199'
- Wilson., W F., Koutrakis, P, Spengler, JD, "Diurnal variations of aerosol acidity, sulfate ;
ammonia in the atmosphere" presentation at _the_Mth_anmi&L meeting and e>diMtiQn_AWJ
Vancouver, British Columbia. June 16-21 (1991).
6 Waldman, J.M., Lioy, l\J., Thurston. G.D. and Lippmann, M., "Spatial and temporal pattern:
summertime sulfate aerosol acidity and neutralization within a metropolitan area." Atmosph
Environment. Vol 24B, pp 115-126, (1990).
7 Last, J.A., Hyde, D.M., Guth, D.J., Warren, D.L "Synergistic interaction of ozone and respir
aerosols on rat lungs I Importance of aerosol acidity." Toxicology Vol. 39, pp 247-257, (1986)
768
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Diurnal and Spatial Variation in Fine and Coarse Particle
Concentrations in Metropolitan Philadelphia
//.//. Suit, G.A. Allen, P. Kuulrukis
Harvard University
School of Public Health
665 Huntington Avenue
Boston. MA 02115
W.F,. Wilson, R.M. Burtun
Atmospheric Research and Exposure Assessment Laboratory
U.S. HPA
Research Triangle Park, NC 27711
Particle mass (I'M, ., and l'M10) concentrations were measured in
metropolitan Philadelphia during (he .summer of 1992, as pari of a larger
effort to characterize acid aerosol concentrations within urban environments.
Sampling was performed simultaneously at seven sites located with metropolitan
Philadelphia and at a ruta] site approximately 18 miles from the city center. Sites were
selected based on their population density and on their relative locations within
Philadelphia. Particle sampling at the eight sites was performed on alternate days, with
sampling conducted over 24-h periods beginning at Xam. All samples were collected
using 10 L iiiin ' Harvard Impactors. At one of the metropolitan sites, additional
par tide mass measurements were made daily using continuous methods.
In this paper, we examine and compare the temporal and spatial variation in
fine (da < 2.5 urn) and coarse (2.5 < d, < 10 um) particle mass concentrations. The
analysis of temporal variation examines the daily and hourly variation in fine and
coarse mass concentrations and their relationship to measured PM10 levels. Daily
leinpoial piofiles for fine and coarse particle concentrations also were compared fot
the eight sites, with factors affecting their daily variation discussed. Similarly,
factors aflccting spatial variation in fine and coarse particle mass concentrations also
were identified, with the specific effects of population density, traffic, location, and
wind diiection addressed. Results from these analyses will help epidemiologists
understand how well, or poorly, measurements of fine, coarse, and P.Y1 h aerosols
collected from a single urban monitoring site are able to characterize
daily particle concentrations within an urban area.
769
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Indoor Air Chemistry: Formation of Organic Acids and Aldehydes
Junfeiitf Zhang and Pan! J. L toy
Environmental and Occupational Health Sciences Institute (EOHSI)
U.Vf DNJ - Robert Wood Johnson Medical School and Rutgers University
681 Frelinghuysen Road
P.O. Iiox 1179
Piscataway, NJ 08855-11792
William E. Wilson
Atmospheric Research and Exposure Assessment Laboratory
U.S EPA. MD-75
Research Triangle Park. NC 27711
Laying emphasis on the formation of aldehydes and organic acids, the study
has examined the gas-phase reactions of ozone with unsaturated VOCs. The formation
of formaldehyde and formic acid was observed for all the three selected unsaturated
VOCs: styrcnc, limonene, and 4-vinylcyclohexcne. In addition, bcnzaldehyde was
detected in the styrene - ozone - air reaction system, and acetic acid was also found in
limonene - ozone -air system. The study has also examined the gas-phase reactions
among formaldehyde, ozone, and nitrogen dioxide and found the formation of formic
acid. The nitrate radical was suggested to play an important role in converting
formaldehyde into formic acid. Experiments for all the reactions were conducted by
using a 4.3 m~' Teflon chamber. Since the conditions for the reactions were similar to
those for indoor environments, the results from the study can be implicated to real
indoor situations and can be employed to support the findings and suggestions from
the previous studies: certain aldehydes and organic acids could be generated
by indoor chemistry.
770
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OZONE REACTIVE CHEMISTRY ON RESIDENTIAL SURFACES
Richard Reiss, P. Barry Ryan, Petros Koutrakis and Sarah J. Tibbetts
Harvard University, School of Public Health
665 Huntington Avenue, Boston, MA 02115
ABSTRACT
The heterogeneous chemistry of ozone on interior latex paint was investigated in a tube flow reactor.
The emissions of several polar volatile organic compounds (VOCs) including organic acids, aldehydes and
ketones were measured while a glass mbe coated with latex paint was exposed to clean air and two
different concentrations of ozone. Formic and acetic acid were not found to be generated via ozone
reactions: however, both were found to oftgas from the latex paints. Formaldehyde, aceraldehyde and
acetone were found to be produced by ozone reactions. It w as found that formaldehyde is produced in
sufficient quantities to impact indoor concentrations. Additionally, ozone, organic acids, aldehydes and
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MATERIALS AND METHODS
Laboratory Study
The formation of polar VOCs via ozone reactions was measured in a laminar tube flow reactor. Reiss
et al. (9) gives a detailed description of the apparatus. Basically, a zero-air (i.e., clean air) or zero-air with
ozone (generated with a UV Photometric Ozone Calibrator) stream is pumped through the tube and
exposed to a glass cylindrical test section that is coated on the inside with latex paint. The test section is 30
cm in length and 2.1 cm in diameter. The flow rate through the test section was 2.5 Lv'min. Several
brands of latex paint were tested. The concentrations of ozone and carbonyls (aldehydes and ketones
though Q) or organic acids, depending on the experiment, were measured before and after the test
section. Organic acid concentrations were measured by glass annular denuders coated with potassium
hydroxide (KOI 1) that were placed in-line. After the experiment the denuders were extracted with ultra-
pure water, and the extract analyzed by High Performance Liquid Chromatography (HPLC) for formate
and acetate ions. Carbonyl concentrations were measured with 2,4-diiiitrophenylhydrazine (DNPH) Sep-
Pak. The Sep-Paks were extracted with acetonitrile and the hydrazone derivative was measured by HPLC.
Ozone concentrations were measured with continuous, chemilumineseent ozone analyzers (Monitor Labs
Model 8410).
For a typical experiment, a latex paint coated tube was first exposed to a zero-air stream. Carbonyl
experiments lasted for about 3 hours, and organic acid experiments lasted about 18 hours. After the initial
zero-air exposure, the tubes were exposed to ozone at about 75-100 ppb. For carbonyls, there was an
additional exposure to a higher ozone concentration. 100-150 ppb.
Modeling Ozone. Heterogeneous Chemistry
Tiie deposition of pollutants to indoor surfaces is typically modeled by the concept of the deposition
velocity, which can be written as follows,
J°>
(1)
w here J0' is the flux of ozone to the surface and C is the indoor ozone concentration. The deposition
velocity can be divided into a boundary layer mass-transport and surface uptake component, where the
surface uptake is modeled by the mass accommodation coefficient, (10) The mass accommodation
coefficient is defined as the ratio of the number of ozone molecules that deposit on the surface and the total
number of ozone molecules that collide with the surface. To model heterogeneous chemistry we have
defined a new term, referred to as the VOC formation factor, which is essentially an extension of the mass
accommodation coefficient. The VOC formation factor is defined as the ratio of the number of VOC
molecules of a particular species that are formed via an ozone reaction and the number of ozone molecules
that deposit on the surface, 'litis factor can be determined from the chamber experiments by a simple mas,1
balance. We can extrapolate the chamber experiments by use of the following steady-state relationship,
jvoc = K * jo,
where Jvoc is the flux of VOC emitting front the surface formed via an ozone reaction and K is the VOC
formation factor.
Description of Field Study
The field study was conducted in two phases, one during the winter and one during the summer. In tf
winter phase we sampled in 4 residences during February, 1993, and in the summer phase we sampled ir
9 residences (including the four winter phase, residences) during late May and June of 1993. The
residences were all in the greater Boston area and included both apartments and houses. Homes with
smokers were excluded, and wood burning fireplaces were not used in any of the residences while
sampling occurred. Sampling was done over an approximately twenty four-hour period, and each
residence was sampled twice, on consecutive days. Carbonyls were measured with Sep-Paks. and
organic acids were measured with KOH denuders. Ozone was measured with sodium nitrite-coated
passive monitors, (see ref. 11). The air exchange rate of the residence was measured by the steady-state
tracer-gas technique, (see ref. 12).
The following is a summary of the sampling protocol for our study:
772
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Indoor Sampling
For the indoor sampling, there was always one centrally located sampling sire. For larger residences
(i.e., ones with more than oite floor), there was an additional sampling site. The following is a description
of the sampling arrangement for each pollutant and environmental variable.
• Carbonyls - One co-location (i.e., two measurements at the same location) at the central site.
For large residences there was an additional sampling location where a single measurement was
made.
• Organic Acids - One co-location at the central site. For large residences there was an additional
sampling location at which a single measurement was made.
• Ozone - One co-location at the central site. Also, there were ozone monitors placed at 2 to 5
other locations in the residence, depending on the size of the residence.
• Air Exchange Rate - Tracer-gas collection tubes were placed in 2 locations during the winter, and
2 to 5 locations during the summer when the air exchange rate is higher, resulting in lower
collection masses on the tubes.
• Temperature and Relative Humidity - Measured at a single, centrally located position.
Qntdwr Sampling
For the outdoor sampling, there was a single, sampling location that was placed at least a meter away
from the residence so that the samples were outside the boundary layer around the residence. At this site,
there were co-located Sep-Paks, KOH denuders and ozone monitors.
RESULTS AND DISCUSSION
Laboratory Study Results
The organic acids were found to offgas from the latex paint at significant quantities during the zero-air
exposure. I 'or acetic acid the offgasing was dependent on the relative humidity. For example, for one
particular brand of latex paint, tlie acetic acid emission rate was 1 jo.g/hr for a 10% relative humidity
:xperimem while the emission rate was 60 jig/hr for an 80% relative humidity experiment. When ozone
vas added, there was no increase in the emission rate, indicating that there is no organic acid formation via
izonc reactions.
Several of the carbonyl compounds were found to offgas from the latex paint during the zero-air
xposure, including formaldehyde, acetaldehyde and acetone. The formaldehyde offgasing was the
ighest. None of the higher molecular weight compounds were detected. In several of the experiments,
'e observed the production of a secondary pollutant from an ozone-latex paint reaction, as evidenced by
ie increase in the emission rates of these compounds when the latex paint tubes were exposed to ozone,
~r a few of the experiments, the emission rate is clearly linear with respect to ozone. It is expected that at
>me unknown ozone concentration the VOC formation will begin to level off asymptotically with respect
ozone deposition due to the saturation of sites where the ozone reaction is occurring. This does not
>pear to be happening for the experiments reported. Most of the experiments showed formaldehyde
oduction, but a few showed acetaldehyde and acetone production.
Using the model developed above, we can extrapolate the results from this laboratory study to actual
door air environments. However, to do this we need to make some assumptions about the concentration
ozone, the deposition of ozone and the air exchange rate of the residence. Therefore, we will return to
s question after discussion of the field study results.
'Id Study Results
The indoor and outdoor concentrations and emission rates were calculated for all of the pollutants,
iss fit at. (7) provides a detailed summary of these results. Table 1 shows the indoor concentrations of
polar VOCs. Among the carbonyls, 10 of 12 that were measured were detected. Only acrolein and
tonaldehyde were not detected. All of the compounds were detected in higher concentrations indoors
:ipared to outdoors, indicating that there are indoor sources for these compounds. The concentrations
the carbonyls were similar for the summer and winter. Ilowever, the average air exchange rate for the
ter was 0.9 lir !, and for the summer it was 2.3 hr'. Therefore, the carbonyl emission rate was much
icr for the summer. The organic acid concentrations were about twice as high for the summer
lpared to the winter.
leveral statistical test were conducted to examine this data. First, the inter-correlations between the
i VOCs were calculated using the Spearman correlation coefficient. Most of the compounds were
773
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Table 1. Summary of Polar VOC Concentrations in Field Study
Compound Winter Cone, (ppb) Summer Cone, (ppb)
Indoor Outdoor Indoor Outdoor
Organic Acids
Formic Acid 9.8 3.1 17.8 3.9
Acetic Acid 15.5 1.8 28.7 2.0
Carbonyls
Formaldehyde 11.1 3.1 16.1 2.6
Aceiaidehyde 6.4 1.5 5.1 1.1
Acetone 6.7 1.4 6.1 1.7
Propionaldehyde 1.1 0.21 1.9 0.83
Butanone 2.4 1.5 2.9 1.2
Butvraldehvde 0.62 0.26 0.56 0.13
Beiizaldehyde 0.70 0.42 0.51 0.08
Isovaleraldehyde 0.35 0.04 0.12 0.01
/i-Valeraklehyde 0.96 0.80 1.1 0.09
n-Hcxaldchyde 1.4 0.03 2,2 0.16
correlated with one another, indicating that these emission rates are controlled by similar processes. We
also tested some models to determine which factors are the most important determinants of the VOC
emission rates. Anderson et al (13) have found that formaldehyde emissions from pressed wood
products was dependent oil the relative humidity of the air above the surface. It is also expected that
temperature will affect the emission rales. Additionally, we have hypothesized that these compounds are
formed via ozone reactions on surfaces and in the gas-phase. The models were derived from simple mass
balance considerations and using the compartmental model approach. The derivation of these models are
provided in Reiss ft al.. (7),
Three different models were tested: (1) a VOC emission rate versus environmental variable model,
separately considering indoor temperature, indoor relative humidity and outdoor temperature, (2) a VOC
emission rate versus ozone removal rale model and (3) a VOC emission rate versus combined
environmental variable and ozone removal rate model. These models were tested for each of the polar
VOC compounds that were detected. The environmental variable terms in model (1) were statistically
significant for most of the compounds, particularly indoor relative humidity and outdoor temperature. Th
ozone removal rate term was significant in model (2) for most of the compounds. It should be noted that
these terms were not significant for the summer or winter data set separately. For model (3), the
environmental variable term was more statistically significant compared to the ozone term for most of the
compounds, suggesting that the environmental variables are a more important determinant of the polar
VOC emission rate. However, two compounds, n-valeraldehvde and formic acid, showed a higher
significance for ihe ozone term, suggesting that ozone was a more important contributor to the polar VOC
emission rates for these compounds. A calculation was also performed to estimate the fraction of the pol
VOC emission rate that can be attributed to ozone reactions based on the regression coefficients of the
model. The calculation showed that about 15 to 60 percent, depending on the compound, of the polar
VOC emission rate can be attributed to ozone reactions.
Extrapolation of Laboratory Results
We can now use the results of the simultaneous measurements of the carbonyls and ozone from the
field study to estimate Die impact of the ozone-latex paint reaction on the total emission rate of
formaldehyde. In the field study we found the following during the summer phase: (1) indoor
774
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formaldehyde concentration - 16.1 ppb, (2) formaldehyde emission rate - 2.3 Hg/m3, (3) outdoor ozone
concentration - 26.3 ppb. (4) air exchange rate - 2.6 hr', and (5) average volume (V) - 300 m'. By
examining the floor plans of the residences that were sampled, we estimate that AJV to be about 1.0 nr1,
where A, is the surface area of only the latex paint. Additionally, the ozone flux to the surface was
modeled by a method outlined by Cano-Ruiz et at. (14). This model considers both laminar and turbulent
flow scenarios. With the ozone flux to the surface and the VOC formation factor, we can determine the
VOC flux from the surface. With the surface area and volume, we can then determine the VOC emission
rate. For a high end value of the VOC formation factor, 0.25, the calculated source emission rate of
formaldehyde is 0.25 |ig/sec for laminar flow and 0.35 (ig/sec for turbulent flow, which 10.9% and
15.2%, respectively, of the formaldehyde emission rate measured by Reiss et a!., (7). For a low-end
value of the VOC formation factor of 0.03, the source emission rate of formaldehyde is 0.029 (ig/sec for
laminar flow and 0.041 jig/sec for turbulent flow, which is 1.3% and 1.8%, respectively, of she measured
formaldehyde emission rate. The acetaldehyde emission rate was also in this range. Figure 1 shows a
general plot of the VOC formation factor versus the polar VOC emission rate via ozone reactions, given the
assumptions listed above.
O JLammar
• TurhuionI
0.2 0.4 0.6 o.a
VOC Formation Factor
igure I. VOC formation factor versus mass emission rate of formaldehyde, given assumptions
listed in the test.
ONCLUSIONS
It was shown that ozone reacts heierogeneously with interior latex paint to form polar VOC compounds
;luding formaldehyde, acetaldehyde ami acetone. Formaldehyde was formed in sufficient quantities to
luence the concentration of indoor formaldehyde significantly. No evidence was found for the
¦mation of organic acids via the ozone-latex paint reaction. A residential field study showed that the
lur VOC emission rate (both carbonyls and organic acids) were correlated with environmental variables
Juding temperature and relative humidity and the ozone removal rate. A combined ozone and
/ironmental variable model indicated that indoor ozone chemistry may account for about 15 60% of the
ar VOC emission rate, depending on the compound.
77 5
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ACKNOWLEDGEMENTS
This study was funded by the Center for Indoor Air Research under contract no. 90-31. Support for
Richard Reiss was provided by the National Institute of Health training gram number ES07155. Bob
Weker provided advice and technical assistance for the analytical work in this study. Mark Davey also
provided valuable assistance in constructing the sampling equipment. We would also like to thank the
following individuals for making their homes available for our testing: Denise Beliiveau, Michelle Clapp,
Mark Davcy, Jane Hoppin and Jack Spcnglcr. Dr. Haluk Ozkaynak and Dr. Joseph Harrington provided
valuable critiques of the work presented here and made helpful suggestions.
BIBLIOGRAPHY
(1) Molhave. L. (1991) '"Volatile Organic Compounds, Indoor Air Quality and Health," Indoor Air. 1,
357-376.
(2) Wallace, L. (1991) "Volatile Organic Compounds," In: Indoor Air Pollution: A 1 lealth Perspective
(Samet, J.M. and Spengler, J.D., eels.) Johns Hopkins University Press, Baltimore, MI), pp. 251-272.
(3) Sack, T.M., Steele, D.H., Hammerstrom. K. and Remmers, J. (1992) "Concentrations, Decay Rates,
and Removal of Ozone and Their Relation to Establishing Clean Indoor Air," Atmospheric Environment.
26 A, 1063-1070.
(4) Finlayson-Pitts, B.J. and Pitts, J.N. (1986) Atmospheric Chemistry; Fundamentals and Experimental
Techniques. John Wiley & Press, New York, NY.
(5) Weschler, C.J., Hodgson, A.T. and Woolev, J.D. (1992) "Indoor Chemistry: Ozone, Volatile
Organic Compounds, and Carpet," Environmental Science & Technology. 26. 2371-2377.
(6) Zhang, J. and Liov, P.J. (1994) "Indoor Air Chemistry: Formation of Organic Acids and Aldehydes,"
submitted to Environmental Science. & Technology.
(7) Reiss, R., Ryan. P.B, Bamford, S. and Koutrakis, P. (1994) "Measurement of Organic Acids,
Aldehydes and Ketones in Residential Environments and Their Relation to Ozone," to be submitted.
(8) Zhang, J. and Lioy, P.J. (1994) "Ozone in Residential Air: Concentrations, I/O Ratios, Indoor
Chemistry, and Exposures." Indoor Air, in press.
(9) Reiss, R., Ryan, P.B., Koutrakis. P. and Bamford, S. (1994) "Ozone Reactive Chemistry on Interior
Latex Paint." to be submitted.
(10) Reiss, R., Ryan, P.B. and Koutrakis, P. (1994) "Modeling Ozone Deposition onto Indoor
Residential Surfaces." Environmental Science and Technolopv. 28, 50-1-513.
(11) Koutrakis. P., Wolfson, J.M, Bunyaviroch, A., Froehlich, S.E., Hirano, K. and Mulik. J.D.
(1993) "Measurement of Ambient Ozone Using a Nitrate-Coated Filter," Analytical Chemistry. 65. 209-
214.
(12) Diet/, R.N. and Cote. E.A. (1982) "Air Infiltration Measurements in a Home Using a Convenient
Perfluorocarbon Tracer Technique," Environment International. 8, 419-433.
(13) Anderson. I., Lundqvist, G.R. and Molhave. L. (1975) "Indoor Air Pollution Due to Chipboard
Used as a Construction Material.'' Atmospheric Environment. 9. 1121-1127.
(14) Cano-Ruiz, J. A., Kong, D, Balas, R.B. and Nazaroff, W.W. (1993) "Removal of Reactive Gases i
Indoor Surfaces: Combining Mass Transport and Surface Kinetics." Atmospheric Environment. 27A,
2039-2050.
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CASTNet Air Toxics Monitoring Program (CATMP):
VOC and Carbonyl Data for July, 1993 through March, 1994
Duv'ul P. Marios and Eric S. Edgcrlon
Environmental Science & Engineering, Inc.
P.O. Box 1703
Gainesville, FL 32602-1703
The U.S. EPA has. under the auspices of the CASTNet program (Clean Air
Status and Trends Network), initiated the CASTNet Air Toxics Monitoring Program
(CATMP). Volatile Organic Compounds (VOC) and carbonyls and metals are sampled
lor 24-hour periods on a 12-day schedule using TO-14 samplers (SUM.MA canisters)
and dinitrophenylhydrazine-coated (dmph) sorbent cartridges and high volume particle
samplers. Sampling was begun at most sites in July of 1993. The sites are operated by
state and local air pollution control programs and all analysis is perl'oinied by
Environmental Science & Engineering (ESE) in Gainesville, Florida. The network
currently supports 15 VOC sites, of which 7 also sample carbonyls. Three sites sample
metals only in Pinellas County, Florida. Analytical methods for the network are
discussed in two other papers in this symposium (Winslow, 1994; Prentice,1994). The
limits of detection of 0.05 ppb for VOCs allow routine tracking of a wide range of
pollutants including several greenhouse gases, transportation pollutants and
photochcmically-dcrived compounds. The sites range from major urban areas
(Chicago, St. Louis) to a rural village (Waterbury. Vermont). Results of the
fits! three quarters of VOC and carbonyl data collection arc summarized in this
presentation.
777
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Sources and Factors Influencing Personal and
Indoor Exposures to PAIIs and PIITIIAL.ATFS
Ilcituk Ozkayncik, Jumping Xiw, and John D. Spengkr
Department i>C Environmental Health
Harvard School of Public Health
665 Huntington Avenue
Boston, MA 02115
During the fall of 1990, a large-scale field monitoring program for
personal exposure to PM,.-, was conducted in Riverside, California by Reseaich
Triangle Institute, Harvard School of Public Health and the Accurcx Corporation. The
pilot PTEAM (Particle Total F.xposure Assessment Methodology) study, co-sponsorcd
by the EPA and the California Ait Resources Board, collected personal exposure data
on PM „ and elemental mass for 175 residents of Riverside. During this study, indoor
and outdoor concentrations of I'M,,,. PM.«, and elements were also collected at
participants' homes; PAH and phthalatc data were collected in a subset of 125 homes.
Twelve-hour recall time-activity diaries and questionnaires regarding exposure to ETS
and other sources of particles, PAHs and phthalates were also obtained and later uses
in exposure modeling. Measurements showed that most PAHs and phthalates had high
detection rates: 60-100%. Aside from smoking, analysis did not indicate cooking,
spraying, house cleaning activities or proximity to busy roadway as possible sources
of PAIIs or phthalates. Both physical and empirical statistical models were used to
estimate the contributions of outdoor sources, cigarette smoking, and other indoor
sources. Results from modeling showed that: (1) The physical models fit the PAH
data well. Coefficients between model predicted concentrations and observed
concentrations averaged about 0.7. (2) Penetration factors for most PAHs were found
to be very close to one. (3) The estimated average decay rates for PAIIs ranged from
0.4 lo 1,6 per hour with sizable variation. (4) Smoking contributed 20-40% of the
total concentrations of eight PAIIs in homes reporting smoking. (5) Smoking was no;
estimate to be an indoor source of phthalates. (6) In the entire set of homes, outdoor
air contributed more than half the total concentrations of six PAHs, mostly the less
volatile ones, and "other" (unidentified) indoor sources contributed more than half of
three volatile PAHs.
778
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SESSION 18:
INDOOR AIR POLLUTION
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Intentionally Blank Page
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Gas and Particulate Phase Acids, Organic
Compounds and Oxidants in a Sick Room
Kris Wardrup, ],aura 1-ewis. and Delbert J. Eatough
Department of Chemistry, Brigham Young University, Provo, UT 84602
ABSTRACT
Employees in a single large room of the administration building at Brigham Young
University began experiencing respiratory problems in the spring of 1993. A study of the
atmospheric environment in the building was done to see if we could identify any causes for the
appearance of this ''sick room" problem. The concentrations ot' fine particulate phase mass,
sulfate, nitrate, ammonium ion and acidity were determined using diffusion deauder sampling
techniques. The corresponding concentrations of gas phase S02, HN03 and HN02 were also
determined from the denuder sampling results. Concentrations of NO, NO;, O, and
formaldehyde were determined using appropriate Drflger absorption tubes. The concentrations
of total volatile organic material was determined using a charcoal sorbent filter. The
concentrations of each of these species were determined in the "sick room," at two control
locations in the building and in the outdoor environment us a function of time of day for six
different days. Temperature and humidity were also monitored in the various study areas. The
symptoms experienced by the personnel in the room appear to be associated with slightly-
elevated temperature and humidity in the study area, a build-up of oxidants and nitrogen oxides
associated with changes in air recirculation in the room during the evening, and the generation
of emissions during the production of materials for large mailings during the evening.
INTRODUCTION
In April of 1993. employees who work in a large office area in the Abraham Srnoot
Administration Building (ASB) on Brigham Young University's (BYU) Provo, UT, campus
began experiencing health problems. Reported complaints included itching eyes, headaches and
scratchy/sore throats. The affected employees reported their symptoms to the health and safety
department of the University. That department conducted monitoring in the area to determine
if high concentrations of organic compounds and ozone could be causing the health problems
the employees were experiencing. These studies revealed nothing that could account for the
reported health problems.
In keeping with BY'U's continued commitment to employee health and safety a further,
more intensive, study was undertaken. This study included the determination of several
itmosphrric species present in the sick room and at control locations as a function of time
juring a one-week study using a Briefcase Automated Sampling System (BASS) (1), and the
idministration of a symptom questionnaire (hat was to be completed by all employees in each of
he sampled areas. The objective of the study was to determine if there were any significant
lifferences between concentrations of the species determined in the sick room, two control
ooms (the copy center in the Administration Building or the office of a University Vice
'resident), and ambient air.
Sick building syndrome seems to have become prevalent in the early 1970s and is
requently associated with a sealed office building whose environment is controlled by a heating,
entilation and cooling system (HVAC) (2). The National Research Council lias defined sick
uilding syndrome as being characterized by an increased prevalence of certain nonspecific
ealth related symptoms in more than 20 percent of the work force. In addition, general
lonitoring does not show individual pollutants to be at unsafe levels (3). Studies show that sick
uilding syndrome can usually be attributed to synergistic effects of various contaminants as well
i the thermal environment which is dependent on both the air temperature and the radiant
-------
temperature. Radiant temperature, is a function of air velocity and humidity (4).
DESCRIPTION OF THE ABRAHAM SMOOT BUILDING
The Abraham Smoot Building is the administration building tor BYU. Construction was
completed in 1961. There have been no additions or major construction renovations to the
original building. The building consists of four floors, one underground. The. ASB is an X-
shaped building with a total area of 99,182 ft2.
The HVAC system consists of a single central unit that serves the entire building.
Outside air is drawn down from ground level on the north side of the building to the ventilation
system which is contained in the basement The air is then distributed to the entire building via
a series of conduit piping. The minimum ratio of outdoor air to recycled air is 15%. The ratio
of ambient to recycled air is a function of ambient temperature. All parts of the building
receive their air from the same source. Heating and cooling of building air is controlled
separately for each area of the building. During the evening hours, when the building is
unoccupied, the rate of air recirculation is cut by a factor of four for energy conservation
purposes.
EXPERIMENTAL
Sampling system
All sampling was done using a Briefcase Automated Sampling System, BASS. The
sampling system has been previously described in detail (1.5). The air inlet is an 8 mm Teflon
line which flows directly to a University Research Glass (URG) (Model 2000-30k/30 P)
elutriator to remove particles larger than 2.5 jim. The total air flow is 12 sLpm. The air flow
then passes into a Teflon coated aluminum sampling manifold where it enters one of several
sampling devices.
The first sampling df.vice measures the, concentrations of ozone (05), nitrogen dioxide
(N02), nitrogen oxides (NO,), carbon monoxide (CO) and formaldehyde utilizing Drager
absorption tubes (1). Air is continuously drawn through each tube during the sampling period
at a flow rale of 300 niL/min. The flow rale is controlled using a needle valve as a critical
orifice. Flow to each lube was determined at the beginning and end of each sampling period
using a bubble flow meter. The concentration of each species was determined by noting the
coloration change in each Drager tube immediately after each sampling session and converting
the reading to an average atmospheric concentration from the measured flow rate through each
tube and the lotal sampling time.
The second sampling device was a diffusion denuder sampling system for the collection o!
gas phase acids, bases and particles. The sampled air stream passed through a set of micro-
diffusion denuders (URG model 2000- 15B). The first section was coated with a 5% wt
NaHC03/5% wt glycerine solution to remove gas phase acids. The second section was coated
with a 5% wt oxalic acid/5% wt glycerine solution to collect ammonia. The denuder set was
followed by a Teflon filter pack (URG Model 2000-15-ABT) which contained a 25 rnm Teflon
filter (Gelman Science, Zcfltior 1'5I'.J047) followed by a 25 mm Nylon filter (Gelman Science.
Nylasorb 66509). Flow through the system was controlled at 3 L/niin with a critical orifice. Tht
flow was determined at the beginning and end of each sampling period using a bubble flow
meter. This system is designed to measure the gas phase concentrations of S02, HNOj, and
HNO; in the first diffusion denuder tube and ammonia (NHj) in the second diffusion denuder
tube. The particles collected by the Teflon filter were analyzed to determine fine particulate
sulfate and nitrate. The. Nylon filter collected any nitric acid lost from the particles during
sampling.
The third sampling device was a filter pack (URG Model 2000-15-ABT) containing a 25
mm quartz filter (Pallflex) and a 25 mm charcoal impregnated fiber filter (CIF) (Schleister &
Schuull), The quartz filter collected particles and the charcoal impregnated filter collected
-------
volatile organic compounds (VOC). The quartz filter was analyzed to determine fine particulate
carbonaceous material and the charcoal impregnated filter was analyzed to determine total
collected VOC (6).
The air quality questionnaire was designed to determine age, sex, appearance of
symptoms during work, type of symptoms, and severity of reported symptoms. The
questionnaire is identical to that previously used in an National Cancer Institute study of air
quality in commercial aircraft passenger cabins (7) except the questions related to cigarette
smoking were omitted since BYU is a non-smoking campus. It was to be filled out daily by all
employees in each sampled area.
Sample collection
Samples were collected on six days, three times each day, beginning at 8:00am. i2:00pm
and 7:00pm. Each sampling period was three hours long. Days one through four were normal
working days, Tuesday, Wednesday, Thursday, and Friday. Day five was a Sunday, the building
is essentially unoccupied on this day. Day six was the following Monday.
Samples were collected at four different locations:
1) The Sick Room studied is on the basement floor at the end of the northeast hall. This
room houses the Financial Aid department of BYU. It is a very congested business
office, having 40 employees in a 4565 ft2 area. Equipment in the room whose emissions
might affect air quality includes general office equipment such as computers, printers,
and photocopiers. This equipment includes a large, computer-controlled printing facility
which is usually operated each night following a work day to output mailings from the
Financial Aid office. This room was sampled all six days, all 3 daily sessions.
2) The Copy Center is also located on the basement floor, in the middle of the building. It
is a small room when compared to the SR location and it is equipped with extra
ventilation. At most, two employees occupy the room. This room was sampled days one,
two, and three of the study, all 3 daily sampling sessions.
3) The vice-president administrator's office is located on the fourth floor in the same
relative position as the Financial Aid office. The 280 ft2 area is sparsely occupied and
has only one computer. This room was sampled days three through six of the study, all
three daily sessions.
4) Ambient samples were collected from the grating on the air intake system for the
building. Ambient samples were collected only in the morning and evening sampling
sessions to allow the BASS system the required time to recharge the batteries as power
was not available at this location.
Vnalvtical techniques
Samples from the sodium bicarbonate and oxalic acid coated annular denuder sections
vere recovered by washing with distilled/deionizcd water and stored at 4°C until analyzed. The
Teflon and CIF filters were stored at 4°C until analyzed. Field handled blank samples were
ibtained for every three samples collected.
The concentrations of S02(g) and HN'O./g) for each exjjeriment were determined from
nalysis of the base coated denuder section. The NaHCOy'glycerine coating and collected gases
i the denuder annulus were recovered by rinsing with 3 mL of water. The extract solution was
ept refrigerated (4CC) until analyzed by ion chromatography (Dionex Model 2000i) for sulfate
nd nitrate using a NaiCOyNaHCOj eluent. The concentrations of ammonia were determined
y a similar extraction of the acid coated denuder section and colorimetric determination of
783
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ammonium ion in the extract solution (8) The Teflon filter collected material was extracted by
sonication for 20 minutes with 3 mL of water and the resulting solution was analyzed by ion
chromatography. Volatile organic compounds collected by the CIF were determined using
temperature programmed volatilization (6). The carbon impregnated sorbent filters were
analyzed in a stream of N\ by heating the sample from ambient (25°C) to 350T, at a nominal
rate of 10°C/min. Organic compounds desorbed from the sorbent filter were catalytically
converted to CO, and detected by nondispersive infrared spectroscopy. The instrument was
calibrated regularly with three CO? standards. The gas phase compounds collected by carbon
sorbent filters appear to be revolatilized between about 140 and 28irC.
RESULTS AND DISCUSSION
Air quality
The concentrations of the various determined species for each sampling period are given
in Figures 1 and L At no lime during the study did any sampled species reach concentration
levels that exceed acceptable tolerance levels, Table 1.
The concentrations of fine particulate sulfate and S02(g), Figure 2. were both dominated
by ambient sources and did not tend to be higher in the sick room than in the control rooms.
Ambient conditions explain the daily variance, Figure 2. Indoor concentrations were generally
less than ambient.
No detectable concentrations of formaldehyde were measured. The detection limit of
formaldehyde, 0.04 ppm, is lower than the normal formaldehyde of O. lpprn in indoor
environments (9). The concentrations of ambient O, were not unusually high throughout the
various sampling periods, Figure 2, indicating there was no extensive photochemical production
of pollutants in the ambient air which would adversely impact the building through air brought
into the HVAC system (10). The concentrations of ozone in the building were always lower
than in the ambient air, hut not zero. Also, the concentrations of ozone in the sick room were
comparable to those in the administrative office and the copy center. Concentrations of N11,
were generally higher in the building than in the ambient air, Figure 2. NH;i is a reflection of
room occupancy. The concentrations of ammonia were always highest in the sick room,
reflecting the higher occupancy of this room. Figure 2.
NO; and NO„ exhibited abnormal diurnal variations on all days when business activity
was occurring in the building, e.g. on days one, two, three, and four. Figure 1. NO,
concentrations in both the sick room and the copy center were very high in the morning or.
these days and then by the afternoon the NO, concentrations had decreased to near ambient
concentrations, Figure 1. A similar pattern, but with a much less pronounced early morning
maximum, was seen in the administrative office. This diurnal pattern was completely absent on
the last two sampling days, days not preceded by a working day. There was very little difference
between the morning and evening concentrations of NO, on these two days. Days one through
four were a Tuesday, Wednesday. Thursday and Friday. Days five and six were a Sunday and
Monday. The high morning NO„ concentrations, dependent on the preceding day being a work
day, suggest that there was a condition that was unique to the copy center and the sick room
but not the rest of the building.
The diurnal pattern seen in the NO„ and NO; concentrations in the sick room and the
copy center was not present for HN03 arid particulate nitrate. In general, the concentrations ol
UNO, and particulate nitrate showed little variation from room to room, and overall low
concentrations were recorded. Figure 1. I lowever, the concentrations of both of these species
were slightly higher indoors than in the ambient samples. This suggests an indoor source for
both of these species. This was particularly evident on day two (Wednesday) in the copy centei
where concentration of HNO-, was triple the concentrations seen in the other sampling location-
The humidity and temperature in the sick room were both elevated as compared to the
other two indoor study areas. The temperature and relative humidity in the copy center and
784
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administrative office averaged 22 ± 1°C and 43 ± 5%. In contrast, the temperature and
relative humidify in the sick room were 26 ± 1°C and 60 ± 5%. These values border on being
unacceptable for a working environment, Table 1.
Air quality questionnaire
No adverse increase in symptoms during work was reported by occupants of the copy
center or the administrative office. The number of people completing the questionnaire in the
sick room declined each day, from 29 (72.5% of the employees in the office) on the first day of
the study to a low of 6 (15% of the employees in the office) on the last day. However, the ratio
of employees in the sick room who completed the questionnaire and reported symptom changes
while at work was always greater than the 20% standard used to define a sick room, Table 2.
The ratio of percent of reporting women to men reporting symptom changes was always about
4:1. The fact that women are more likely to report symptoms than men has been well
documented (11,12,13,14). The gender issue in reporting symptoms disappears when the
population has hypersensitivity to atmospheric pollutants resulting from allergies, hayfever or
asthma (14). Our results from the questionnaire can be considered typical of the exacted
response from a population residing in a sick room. The three symptoms that were reported to
have the greatest change were itching eyes, headache and scratchy/sore throat. The severity of
symptom change varied from day to day with headache being the most consistently reported
problem.
In the sick room the symptom change was the greatest on day three. Twenty people
completed the questionnaire on that day, sixteen women and four men. The average age was
31 years. An increase in symptoms was reported by twelve of the. respondents. Forty-five
percent of the population stated they had been told they had hay fever. Fifty percent first
experienced a symptom increase in the morning while the other fifty percent reported first
experiencing symptom increases in the afternoon. There was a negative correlation between
peak concentrations of species tested and greatest change in symptoms experienced. On day 3
NH3 showed peak concentration, but that is the only species that exhibited a high concentration.
Day 1 showed the second highest mean symptom change, but again there was a negative
correlation between high chemical species concentration and mean symptom change. On day 6
both 03 and CO showed peak concentration levels in the sick room but the reported mean
symptom change on day 6 was the lowest of all sampled days. However, the sample size on day
6 was small, Table 2.
CONCLUSIONS
The uniqueness of this study lies in the fact that only one room in a large building
?xperienced the reported illness symptoms. Analysis of the questionnaire data showed that we
vere indeed dealing with a sick building syndrome problem (11,12,13,14). The objective of the
ampling program was to identify differences between the sick room and the control rooms
vhich might be related to the sick room problem, and then find the possible source, or sources
>f these differences. It has been shown that sick building syndrome is usually not a result of a
pecific etiologic agent but a combination of factors (12). The only chemical species measured
/hich showed significant differences from normal expected patterns was the unusually high
oncentrations of NO, and NOz in the morning in both the sick room and the copy center,
'igure 1. The abnormal NO* concentrations probably result from the printing processes in both
f these rooms with the associated degassing of NO, from the ink. This process has been
reviously associated with sick building syndrome (15). The printing system in the sick room is
:avily used at night, after a work day. This, coupled with the decreased ventilation during the
ight, probably accounts for the unusually high concentrations of NO, on mornings after the
•inter has been working all night. This would also account for the lack of high morning NO,
mcentrations on the last two days of the study. These two days, Sunday and Monday, were
-------
not associated with computer print runs the preceding night. The presence of elevated NO,
concentrations in association with ozone and volatile organic compounds would he expected to
result in the formation of noxious organic species (10). The other difference between the sick
room and other control rooms in the study was the elevated temperature and relative humidity
present in the sick room. Temperature and humidity have been identified as being factors in
sick building syndrome (16).
In summary, the sick room syndrome was probably due to a combination of three factors
in the sick room: high NO„ concentrations in the presence of VOC. and ozone, high humidity
and elevated temperature. Although any one of these factors alone may not cause an
uncomfortable working environment, the combined effect is apparently enough to cause the
room occupants to become uncomfortable and feel increased illness symptoms. The problem
could be alleviated by moving the printer or increasing the HVAC recirculation during the night,
lowering the room temperature, and finding and eliminating the source of the increased
humidity in the sick room.
REFERENCES
1. Hatough, D.J.. Caka, P.M., Wall, K., et al., "An Automated Sampling System for the
Collection of Environmental Tobacco Smoke Constituents in Commercial Aircraft," in
{Proceedings of the I9H9 AAtVMAjEPA Symposium on the Measurement of Toxic and
Related Air Pollutants; pp 565-576.
2. Robertson, A.S., et al. Br,_Med.J. 1985 291. 373-376.
3. National Research Council; Policies and procedures for Control of Indoor Air Quality,
National Academy Press: Washington, D.C, 1987.
4. Turicl, I., et al. Atmos^Environ. 1983 17, 51-64.
5. Eatough, D.J., Williams, N., Lewis, L., et al., "Gas and Particulate Phase Acids and
Oxidants in Two University Libraries," in Proceed'mgs of the 1991 A&WMA/EPA
Symposium on the Measurement of Toxic and Related Air Pollutants; pp 333-343.
6. Tang, H., Lewis, E.A., Eatough, D.J., et al. AUnps, Environ- 1994 22, 939-947.
7. Mattson, M.H., Boyd, G., Byar, D., et al.. JA&WMA 1989 261, 867-872.
8. Methods for Chemical Analysis of Water and Wastewater, EPA-600/4-70-020; method
350.1, Ammonium, Coroimetric; U.S. Environmental Protection Agency: Research
Triangle Park.
9. Menzies. R., "Impact of Exposure to Multiple Contaminants on Symptoms of Sick
Building Syndrome," in Proceedings of the 1993 International Conference on Indoor Air
Quality and Climate, Vol 1; pp 363-368.
10. Finlayson-Pitts, B.J.. Pitts. J.N.: Atmospheric Chemistry: Fundamentals and Experimental
Techniques; John Wiley and Sons: New York, 1986.
11. Stenbcrg, B., Wall, S., "Why do Females Report 'Sick Building Symptoms' More Often
Than Males?" in Proceedings of the 1993 International Conference on Indoor Air Quality
and Climate, Vol 1; pp 399-104.
786
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12. Stenberg, B., Erikson, N., Hannson, K.. et al., The Office Illness Project in Northern
Sweden—An Interdisciplinary Study of the Sick Building Syndrome (SBS)," in Proceedings
of the 1993 International Conference on Indoor Air Quality and Climate, Vol 1; pp 393-
398.
13. Raw, G„ Grey, A., "Sex Difference in Sick Building Syndrome," in Proceedings of the 1993
International Conference on Indoor Air Quality and Climate. Vol 1; pp 381-86.
14. Levy, F., Blom, P., Skarret, E., "Gender and Hypersensitivity as Indicators of Indoor
Related Health Complaints in a National Reference Population," in Proceedings of the
1993 International Conference on Indoor Air Quality ami Climate, Vol 1; pp 357-362.
15. Fisk, J.W., Mendell, M.J., Daisey, J.M., et al., "The California Healthy Building Study,
Phase 1: A Summary," in Proceedings of the 1993 International Conference on Indoor Air
Quality and Climate, Vol 1; pp 279-84.
16. Sundeil, J., Linduall, T., "Indoor Air Humidity arid the Sensation of Dryness as Risk
Indicators of SBS," in Proceedings of the 1993 International Conference on Indoor Air
Quality and Climate, Vol 1; pp 405-410.
17. Spengler J.D.; Indoor Air Pollution-, J.M. Samel and J.D. Spengler, Eds.; Johns Hopkins
University Press, 1991; pp 4-6.
18. Binnie P.W.H., Indoor Air Quality and Ventilation; F. Lunau and G.L Reynolds, Eds.;
Selper Ltd.: London, 1990, pp 259-268.
19. Meyer, B.; Indoor Air Quality; Addison-Wesley Publishing Co.: Massachusetts. 1983; p
31L
787
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Table 1. Suggested tolerance concentrations for indoor pollutants.
Chemical species Acceptable concentration Source'
NO, 50 ppb EPA (17)
CO 9 ppm NAAQS (17)
CHzO 0.1 ppm ASHRAE (18)
VOC's 2 mg/m3 EPA (17)
03 0.05 ppm ASHRAE (18)
TEMP 20 TO 26° C ASHRAE (18)
RH 20 TO 70 % ASHRAE (18)
Nil, 50 ppm OSHA (19)
¦EPA. Environmental Protection Agency
NAAQS. National Amhicnt Air Quality Standards
ASI1RAE. Modification of American Conference of Governmental Industrial Ilvgicnisis
OSHA. Occupational Safety and Health Administration
Table 2 Results of the questionnaire study.
Day"
T«tal"
Chanpec
Perccntd
1
29
20
69
2
25
16
64
3
20
12
60
4
14
8
57
6
6
2
33
•Day: The day of the study.
"Toial: 'J"hi! tola! number of employees who completed the questionnaire. The average room occupancy is 40
employees.
'Change: The total number of employees reporting an increase in symptoms while at work.
'Percent: The percent of employees who completed the questionnaire and reporicd a symptom increase.
788
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I Horning US Mid-Day ED NlgM
) Morning {ElfcHrf-nay Z?] Night
MOO
2000
1000
Sick Room
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3000
2000
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Sample Day
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Figure 1. Concentrations of NO^g), N02(g), HN03(g) and particulate nitrate at each sampling
location for each sampling period.
7X9
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I Moratng SB Mid-Day E3 Night
\ Morning EH Utd-Day S3 Night
3000
2000
1000
0
LU M
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| Administrative Office
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12008
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Ambient
-------
Tracer Gas Measurement of Indoor-Outdoor
Air Exchange Rates
Kevin X. Gunn and Zliishi Cuo
Acurex Environmental Corporation
P O Box 13109
Research Triangle Park. NC 27709
Bruce A. I'ichenor
Indoor Air Branch
Air and F.nergy Engineering Researcli Laboratory
US Environmental Protection Agency
Research Triangle Park, NC 27711
ABSTRACT
Indoor air quality studies often require the determination of the indoor-outdoor air exchange
rate The air exchange rate is defined as the volume of outdoor air that enters the indoor
environment in I hour divided by the volume of the indoor space Air exchange rates are usually
determined by tracer gas techniques. Researchers at EPA's Air and Energy Engineering Research
Laboratory recently completed a study that compared two tracers and three measurement systems:
sulfur hexafltioride (SF6) measured by a photoacoustic infrared detector. SF,; measured bv gas
chromatography with an electron capture detector, and carbon monoxide (CO) measuied by a non-
dispersive infrared detector. Controlled tests, using the tracer gas decay method, were conducted in a
small ( J66L) environmental chamber. Uncontrolled experiments were run in a test house Data
describing the accuracy and precision of each method are presented
INTRODUCTION
In studies of indoor air quality, a knowledge of the indoor-outdoor air exchange rate is often
necessary The air exchange rate is the rate at which outside air replaces the air in the indoor space
and is defined as the volume of outdoor air that enters the indoor environment (typically per hour)
divided by the volume of the indoor space. A commonly used method for determining air exchange
rates is the tracer decay method. A tracer gas which ideally does not react with the indoor
environment is released into the indoor space and mixed with the indoor air. As outdoor air
infiltrates the indoor space, the tracer gas is displaced and diluted and its concentration declines
according to1
Cm C.e1:' (1)
.vhere
C(r) - concentranon of tracer gas at time t (ppb)
C0 = concentration at time zero (ppb)
k = air exchange rate (h'1)
t = time (h)
V variety of instrumentation and tracer gases are available for conducting tracer decay testing. Tluee
.'chniques are examined here photoacoustic infrared detection of SF,;. detection of SF,; bv gas
hromatoeraphy with an election capture detector (ECD). and CO measured by a non-dispersive
791
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infrared continuous monitor. In this investigation, controlled tests were conducted in a 1661-
stainless steel test chamber, and an uncontrolled test was conducted in a test house
METHODS AND RESULTS
Monitoring Techniques
The three measurement systems used include a Thermo-F.lectron model 4R gas filter
cor:elation CO monitor, a Shimadzu pas chromatograph (GC) with electron capture detector, and a
Briiel and K.jser model 1302 mulli-gas monitor.
CO Monitor The Thermo-Flectron mode! 48 gas filter correlation monitor is a continuous
emission monitor using infrared (IR) detection. The instrument output is updated eveiy 10 seconds
and is connected to a computer running LabTech Notebook for data acquisition. The computer
creates 1 minute averages which arc written to an ASCII data file. The system is normally run with
a 2 minute purge between 1 minute sampling intervals to allow for monitoring-' of multiple indoor
locations, sequentially Although this experiment required only one sampling location, the system
was still operated under its standard operational mode Therefore the sample frequency of the system
was one sample every 3 minutes A multipoint calibration was conducted to ensure linearity. The
system was calibrated over a range of CO concentrations of 0 to 254 ppro
GC/ECD A Shimadzu CiC, equipped with an electron capture detector, was used Sample^
were collected by dual sample loons While carrier gas flows through one loop into the GC, a mass
flow controller and pump puige the second with sample air The GC is connected to a Hewlett
Packard integrator and then to a computer running C-hromPerfect for data acquisition Sample
frequencies of approximately one sample every 4 minutes allowed resolution of the Sh from the air
peak The column used for this analysis was a carbosieve packed column The GC was operated
isothermally at 45'C.
Briiel and Kiar 1302 The model 1302 is a photoacoustic IR gas monitor containing up to
five IR filters and a water vapor filter. Ihe water vapor filter is necessary to compensate for the
presence of IR absorption by water across most of the IR spectrum. The manufacture! states that the
system is linear for at least four orders of magnitude starting at its detection limit of 5 ppb for SF..
The system was factory calibrated and operated with the Briiel and Kjaer 7620 applications software
The software operates the entire system and provides data acquisition. Sample frequency for these
experiments was approximately one sample per minute
Test Chamber Configuration
In older to provide an ideal environment for comparison cf the three techniques, controlled
testing occurred in a 166L stainless steel environmental test chamber. Zero-grade air was supplied to
the chamber at a constant rate using a mass flow controller Mixing sr. the chamber was achieved bv
introducing the air into the chamber through a length of perforated tiibitio coiled around the bottom
of the chamber and by using a small mixing fan near the bottom of the chamber When exiting from
the chamber, the air passed through a sampling manifold which supplied air to each of the monitors
simultaneously. Since the pump for the GC could pull more air from the sampling manifold than
was supplied by the airflow from the chamber, the flow- to the GC was limited by a mass flow
controller Tracers were injected into the chamber via an injection port at the itile' between the mass,
flow controller and the chamber.
Test Procedure for Chamber Tests
In order to evaluate the three techniques under a variety of conditions, tests were conducted a
792
-------
air exchange rates of approximately 0.75. 1.30, and 2.00h' For each air exchange regime, two test.-;
were conducted Actual air exchange rates were determined by measuring the flow rate into the
chamber and dividing by the chamber volume Tracers were then injected and the decay followed
for 2 hours. In each case the first hour of data was discarded in order to allow ample time for the
chamber to become well-mixed.
Data Analysis
Solving for the air exchange rate it: equation (1) yields
Experimentally, air exchange rates for tracer decay data are calculated by using the natural log of the
concentration data as the dependent variable in a linear regression versus time in hours Accuracy of
the method* is examined by comparison of the calculated air exchange rates versus the measured
flow rates. Precision is investigated by examining duplicate tests. Since the photoacoustic monitor
and the CO IR monitor both have linear responses over the range of concentrations used in the
testing, calibration of these instruments was straightforward The HCD, however, was quite non-
linear, Equation (3) was used to convert the raw data (area counts) into concentrations (in ppb):
C = 7 38 + (0 000796-1 )A i (4 6467 > I0")A; (3)
where
C = concentration
A = area counts
It was noted during data analysis that a different curve fit,
gave significantly different results in spite of the fact that the two curves are extremely similar
Figure (l) plots the two curves and the calibration points
Results of Chamber Testing
fable I summarizes the results of the six small chamber tests conducted. Results for the
GC/ECD are given using both of the calibration curves to demonstrate the variation caused by the
slight diffeiences in the curves. Accuracy is defined as 100 - Imeasured - actual,' x 100 I actual
Accuracies for each technique are summarized in Table 2. Fiorn this data, the average accuracies of
the techniques are 95 2% for photoacoustic IR. 96 7% for analysis by fc'CD, and 96.3% for CO via
IR monitor Precision is indicated by the percent difference between duplicate runs Since runs !
and 2 were not (rue duplicates, they are not comparable in this way Precision data are summarised
in Table 3.
Finally, it is important to examine the results across all tuns for each of the three techniques
Using a Student's t-test can determine if the differences between the results of each technique and the
actual air exchange rates are due to normal statistical variation or represent true discrepancies If a
series of data points has a t-value less than t(0 05), then the results of the technique may be
considered to be equivalent to the actual air exchange rate with vaiiations being attributed to normal
statistical error. For this evaluation, all data were normalized to allow equal weighting of data across
each of the air exchange regimes examined The results of the t-test indicate that the air exchange
rates determined by each of the three methods are correct within normal statistical variation.
However, air exchange rates calculated by the application of equation (4) to the GC/ECD data fail to
3ass the t-test and therefore show error which cannot be attributed to normal statistical variation
k -In[C(t)/C0]/t
(2)
C =¦¦ -ln( 1 - A < 490300) / 0.00149
(4)
-------
Uncontrolled Testing in Test House Environment
In addition to the controlled testing previously described, a single uncontrolled test using the
three techniques was conducted in a test house located in Cary, NC. The house used is a three
bedroom single-slory dwelling with central heating'air conditioning. The internal volume of the
house is 305 m". The attached garage has been converted to laboratory space where all the monitors
used in this test were located.
The test was conducted by dosing the house with CO and SF6 through Vi-inch Teflon lines
leading into the air handling system's return air vent. Approximately 27L of CO and 8.6L of SF6
were released. The heating/air conditioning fan was kept on continuously to guarantee good mixing.
Indoor temperature was set for 22"C. Each of the monitoring systems sampled from the house via
independent sampling systems. The GC system used a pump which pulled sample from the house
directly through the sampling loops The CO monitor has an internal pump which sampled from a
sample stream (since the internal pump was not strong enough to pull from the house). The Brucl
and Kia:r system has an internal pump which pulled directly from the house. All three systems
sampled from the same location in the den of the house. Linear regressions from the resulting data
were conducted over 1 hour time periods after an initial Vi hour of data was discarded for mixing
purposes for each of the methods. The air exchange rales determined by each of the three detectors
ranged from 0.50 to 0 52.
CONCLUSION
All three methods investigated yielded results which are statistically equivalent to the actual
air exchange rates. Data analysis for the CO analyzer and the photoacoustic IR monitor was straight-
forward since both those instruments exhibit a very linear response over the range of concentrations
used ir. this testing. The analysis of the ECD data was complicated by the non-linear nature of this
particular detector. While it is possible to obtain accurate air exchange rates from each of the
systems using the tracer decay method, it is recommended that the detector used have a very linear
response over the range of interest in order to avoid possible confusion caused by the difficulty of
ensuring an accurate fit to the calibration data generated by a non-linear system. In order to be
confident that the calibration curve assigned to a non-linear detector is acceptable for tracer decay
determination of air exchange rates, the system must be tested by applying the fit to data from a
controlled environment with a known air exchange rate.
794
-------
Table 1 Measured versus actual air exchange rates.
TF.ST
ACTUAL
SF0 VIA
SF, VIA
SF., VIA
CO VIA IR
NUMBER
ACH4
PHOTO-
GC/ECD
GC/ECD
ACOUSTIC
EQUATION
EQUATION
IR
(3)
(•¦>)
1
0.79
0.85
0.85
0 74
0 86
2
0.74
0.74
0.74
0 64
0.70
3
1.98
221
1 88
1 79
1 94
4
1.98
2.16
I 86
1 79
1 93
5
1 27
1 27
1 27
1.09
1 29
6
I 27
1 26
1 28
1.10
1.25
Table 2. Accuracy of Techniques.
TEST NUMBER
SF, VIA PHOTO-
SF, VIA GC/ECD
CO VIA IR
ACOUSTIC IR
92 '1
100
88 4
90.9
100
99.2
92 4
100
94.9
93.9
100
99.2
91.1
94 6
98,0
97.5
98.4
98.4
Table 3. Percent differences within duplicate runs.
TEST
NUMBER
3 & 4
5 & 6
SFf VIA
PHOTOACOUSTIC
IR MONITOR
2.29
0.79
SF6 VIA GC/ECD
1 07
0 78
CO VTA IR
0.52
3.15
795
-------
400000
w 300000 -
O 200000 -
< 100000 -
——i—
0 200 400 600 800 1000
SF6 (ppb)
a Area Counts — Exponential — Polynomial
Figure 1 Comparison of calibration curves
Reference
t. ASHRAE (1985): "Fundamentals Handbook," ASHRAk, inc., Atlanta, GA, page 22 8
796
-------
Measurement of Airborne Particle Counts and Mass in a Health}' Building
During a One-Year Cleaning Effectiveness Study
K.E. Lee.se, RC. Cola. R.M. Hall
Research Triangle Institute, Research Triangle Park, NC 27709
and
M.A. Berry, U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
ABSTRACT
The Research Triangle Institute, under a cooperative agreement with the U.S. EPA's
Environmental Criteria and Assessment Office conducted a year-long field study to understand and
assess the effectiveness of an improved cleaning program to better indoor air quality. A four-story
healthy building was monitored with a Laser Particle Counter (LPC), commonly used in clean rooms,
to characterize airborne particle size ranges of >0.5 to >15 Mm. Monitoring was also done with a
Fine Particle Sampler (1-PS) that measures airborne dust mass concentrations which are routinely
used to assess dust exposure and potential health effects. LPC and HPS measurements were taken
once monthly on each floor for five months, with building housekeeping performed as usual. Profes-
sional cleaners then deep cleaned the building which included walls, windows, furniture, light fix-
lures, hathrooms. and tiled and carpeted floors, after which, an improved cleaning regimen was
instituted and monitoring continued for seven months.
While LPC total particle counts correlated well with those outdoors, they were of limited value,
providing particle size distributions which did not correlate with total airborne particle mass. Mean
total particle count size distributions were similar oh the four floors -- decreasing as particle size
increased, and they remained relatively constant over the study. On the second floor, I.PC large
particle counts (5, 10. 15 (im) decreased significantly, while small particles (0.5, 1 fim) increased
immediately after cleaning. LPC particle counts may be most useful in preliminary site evaluations
or in locating bioaerosol sources. FPS mass particle mass concentrations were low in the building
(5 to 11.5 The second floor, a child care facility which had the greatest activity levels and
multiple accesses to an outdoor sand moat, also had the highest concentration of total airborne dust.
In comparing the two modes of measurement in a healthy building. FPS total airborne dust mass
gave the most meaningful data and showed a 48% improvement with improved cleaning.
INTRODUCTION
The Research Triangle Institute (RTI), under a Cooperative Agreement with the U.S.
Environmental Protection Agency's (EPA) Environmental Criteria and Assessment Office conducted
t year-long, field study to understand and assess the effectiveness of an improved, cleaning program
o better indoor air quality. The building was 20 years old, and had four-stories with a total of
!8,000 ft3. The. multi-use building consisted of day care, offices, and medical laboratories. The
milding is inset into a hill such that there are ground level entrances on the first, second, and third
loors. The building had no history of indoor air complaints, and after an intensive screening at the
icginning of the study, it was considered to be a healthy building. The building was monitored with
Laser Panicle Counter (LPC), commonly used in clean rooms, to characterize airborne particle size
inges of ><).5 to >15 pm. Monitoring was also done with a Fine Particle Sampler (FPS) that meas-
res airborne dust mass concentrations, which are routinely used to assess dust exposure and poten-
al health effects. The EPA uses airborne particle mass to define their national ambient air quality
M,0 (particles less than 10 pm) standard. LPC and FPS measurements were taken monthly on each
-------
floor. For live months, measurements were taken while building housekeeping was performed as
usual. Professional cleaners then deep cleaned the building which included walls, windows,
furniture, light fixtures, bathrooms, and tiled and carpeted floors. Some airborne particle
measurements were taken soon alter deep cleaning, after which, an improved cleaning regimen was
instituted and monitoring continued monthly for seven months.
METHODS
LPC measurements were taken with a Met-One Model 217 Laser Particle Counter. The. unit
measures panicles >0.5pm on one channel and particles >1. >5, >10, or >15 (jm simultaneously on
another channel. The user must select each particle size >0.5 jim separately and take multiple
measurements to get particle counts of the other particle sizes. The sample rate was (!. 1 elm, and
one-minute samples were taken for each particle size at two or three locations on each of the four
floors on a sample day. The unit was placed at different heights from the floor according to activity
levels in each location. Sampling heights were 30 cm in day care areas, 90 cm in offices, and
120 cm in halls. Outdoor samples were also taken at ground level on the 1st and 3rd floors, and on
the roof at the air intake.
FPS measurements were taken with a URG (Carrboro, NC) Fine Particle Sampler. The unit has
an adjustable inlet positioned over a filter which can be set to various particle size cut points For
this study, it was set to collect total aiiborne particulates. The unit was used to draw air at 28 liters
per minute through a 3 (am polycarbonate filler for 24 hours. Measurements were taken once
monthly on each floor of the building in a hallway. The filter was positioned at approximately
I meter above the floor. The filters were weighed or, a Perkin-tlmer MicrobaSance which was cali-
brated with NIST traceable weights. Filters were equilibrated at 471 relative humidity pnor to
weighing. A laboratory control filter was used throughout the study, and field blanks were used as
measures of quality control.
RESULTS
The particle size distribution for the second floor as shown in Figure 1 was similar on all floors
of the building during the study. As particle size increased, counts decreased for all indoor and
outdoor measurements. A comparison of mean total particle counts indoors and outdoors is shown in
Figure 2. Outdoor counts correlated well with, and were consistently higher than indoor counts. The
second floor showed the most dramatic reduction of airborne panicles immediately after cleaning
(Figure 1) for all but the smallest particle, size range (0.5 pm) which showed a slight increase. For
particles >1 ^m. >5 urn, and >10 (am aerodynamic diameter, the. second floor had statistically
significantly greater particle counts than the other three floors (p<05). Particle counts at each
sampling location were relatively uniform over time, but there were often large differences between
sampling locations on each floor of the building. Mean particle counts were relatively constant on
each floor over the course of the study.
Mean total airborne dust mass concentrations for the study as shown in Table 1 were low in the
building, ranging from values of 5.0 i^g/m' on the 4th floor to 11.5 ug/rrr on the 2nd floor. The
EPA PM,.j standard is 50 |ig/m' fur 24 hour annual average, and 150 (lm/m1 for individual daily
averages. Airborne dust concentrations were 44-51% lower on each floor in the period following
deep cleaning than before cleaning, despite wide variations in monthly measurements. The building
mean airborne particle concentration during ths improved housekeeping period was significantly less
(p<05) than during routine housekeeping. Figure 3 shows the mean monthly airborne dust mass data
for each floor during the study.
708
-------
CONCLUSIONS
Monthly, individual, panicle counts and airborne, dust mass did not correlate. This may be due
to the very different methods by which the two measurements were made. Panicles were counted
for very short periods (1 minute sampling) and all floors were monitored on the sampling day, while
24 hour samples were taken on consecutive days for mass determinations. Because air in a building
may not bo well mixed everywhere, short-term air sampling in various locations may yield samples
that represent a range of particle counts in a relatively nonhomogeneous airstream. Airborne dusl
was collected for 24 hours, effectively integrating many small samples into a larger one. Preferably,
particle counts should be taken several times during the period in which dust mass samples are taken
and probably should include additional sampling locations.
Overall, counts of particles and mass concentrations of airborne dust were consistently higher
on the. second floor than on the others. Generally, the lowest panicle counts and airborne dust mass
levels were on the fourth floor. Higher airborne panicle counts and dust masses on the second floor
may have been influenced by several variables. First, there was frequent opening of doors to the
outdoors along the sand moat play area, and the propping open of second floor hallway doors, which
was a common practice during much of the study. This practice may have effectively lowered the
air pressure on the second floor, allowing infiltration of outdoor air and particles. This effect would
be consistent with higher indoor panicle counts observed in telecommunications buildings following
shut-down of HVAC fans.1 Secondly, day care residents (of whom there are 50 on the 2nd floor)
and workers also track in soil from the sandy moat, potentially contributing elevated airborne particle
loads. Surface contamination, whatever its origin, may become airborne and inhaled by workers or
casual passers by.J Also, floors in hospital wards contaminated with large numbers of bacteria have
been implicated as reservoirs of hospital infection through the dispersal of the bacteria into the air/
Entrances to the other floors of the building have concrete aprons or staircases that may reduce the
amount of tracked in dirt. In addition, there were greater activity levels on the second floor
associated with rooms full of children, indoor sand and water boxes, a small kitchen, and pet animal
cages, as opposed to floors with offices and laboratories -- such as the fourth floor having less dense
occupancy.
Mean total airborne panicle counts remained relatively stable over the entire study, unlike
airborne dust mass, which showed a 52% decline after total building cleaning. Panicle count data
revealed nonhomogeneous local microenvironmer.ts, but mean panicle counts reflected the fact that
building use remained constant over the course of the study. Panicle counts may provide better
measures of the homogeneity of an indoor environment, ajid may be a more sensitive measure of
variations from the mean in specific locations. Thus, particle counters may be most useful in surveys
to detect nonhomogeneities of indoor air, such as searching for sources of biopollutants. Recause
particle counts yield immediate results and are relatively inexpensive, their greatest advantage may
be in obtaining preliminary information for a sampling plan in a complaint situation. Additional
research is needed to determine the role of particle counters in screening and/or assessing indoor air
quality.
The institution of improved cleaning practices accompanied the general decline in airborne dust
mass seen from January - July, 1993. One such practice, the use of damp, disposable dust cloths,
may have contributed to this. Cleaning re-disburses dust, and it is generally believed that dry
methods stir dust more than wet methods.4 Total LPC panicle counts were comprised by several
Drders of magnitude of particles <0.5 pm. Most smaller panicles probably remained suspended, and
Dnly larger particles settled on surfaces that were dusted. Since the mass contributions of larger
¦(articles is disproportionate to their numbers, removing larger, heavier settled particles may not
if feet overall particle counts, while decreasing the mass of suspended panicles. FIKL' airborne mass
•oneentrations provided the most useful data in this study, showing a significant improvement after
leep cleaning and improved housekeeping. Airborne mass concentrations are also likely to be the
nost useful in determining the potential for health effects.
799
-------
O 1x10
~i i i i i i i i i i i i r
Jul Sep Oct Nov Dae Cln Aft Jan Fab Mar Apr May Jun Jul
1x10
Figure 1. Particle Counts on Second Floor
1x10
£
"a
1x10
• « _ . ~
\ \
" "A < / * /
/ V A' A /¦
V •>/ • '
\
V
Indoors
- - - Outdoors
1x10
1 1 1 1 1 1 1 1 1 1 1 1 1
Jul Sep Oct Nov Dec C!n Att Jan Feb Mar Apr May Jun Jul
Figure 2. Total Particle Counts - Indoors and Outdoors
800
-------
Floor 1
Floor 2
Floor 3
Floor 4
, 1 1 ( 1 1 I 3 1 I 1 1 1
Jul Sep Oct Nov Dec Cln Aft Jan Feb Mar Apr May Jun Jul
Figure 3. Monthly Airborne Dust Mass
801
-------
Table 1. Airborne Dust Mass in pg/m3
Building
Phase
Date
Floor 1
Floor 2
Floor 3
Floor 4
Mean
Routine
9/10/92
24.4
26.6
6.9
3.8
154
Housekeeping
10/8/92
16.8
31.5
9.9
9.0
16.8
11/12/92
11.2
11.9
13.3
8.8
11.3
12/10/92
4.4
3.5
2.8
6.1
4.2
Mean
14.2
18.4
8.2
6.9
11.9
Std Dev
8.5
12.9
4.5
2.5
5.7
During Deep I
Cleaning | 12/19/93 (a)
13.6
After Deep
Cleaning
12/23/93 (a)
4.5
Improved
1/14/93
3.8
3.0
3.6
3.4
3.4
Housekeeping
2/11/93
9.7
9.7
6.2
5.7
7.8
3/18/93
4.3
12.5
3.0
1.2
5.2
4/15/93
1.4
10.3
39
1.8
4.4
5/13/93
8.3
5.2
2.6
4.1
5.0
6/10/93
9.3
5.9
6.2
4.1
6.4
7/8/93
11.9
6.9
4.9
6.8
7.6
Mean
6.9
7.6
4.3
3.9
5.7
Std Dev
3.8
3.3
1.5
2.0
1.6
Year (b)
Mean
9.6
11.5
5 8
5.0
8.0
Std Dev
6.6
9.3
3.3
2.6
4.6
Change from Routine
to Improved Housekeepinq
-51%
•58%
-47%
-44%
-52%
a - Measurements were taken on the second floor only during and after cleanin
b - Year-long mean for routine and improved housekeeping only
802
-------
acknowledgement
The research presented in this document was funded by the U.S. Environmental Protection
Agency under Cooperative Agreement number CR-815509-02-1 to the Research Triangle Institute.
DISCLAIMER
Mention of trade names or commercial products does not constitute endorsement or recommen-
dation for use by the U.S. Environmental Protection Agency or the Research Triangle Institute.
REFERENCES
1. Krzyanowski, M. E.. "Use of Airborne Particle Counting to Evaluate Indoor Air Quality for
Remediation and Control,'' in Environments for People: IAQ92., American Society of Heating,
Refrigeration, and Air-Conditioning Engineers: San Francisco, CA, October, 1992; pp 415-426.
2. Sansone. E.B.; Treatise on Clean Surface Technology; K. L. Mittal, Editor; Plenum Press, New
York and London, 1983; pp 261-289.
3. Ayliffe, G.A., et al. J. Hyg.Camb. 196765,515-536.
4. Schneider, T., ct al., "Cleaning Methods, Their Effectiveness and Airborne Dust Generation," in
Proceedings of Indoor Air '93. Vol. 6, The 6th International Conference on Indoor Air Quality and
Climate: Helsinki, Finland, July, 1993; pp 327-332.
803
-------
Effects of Activated Charcoal Filtration and Ozonation
on Hydrocarbon and Carbonyl Levels of Ambient Air
Used in Controlled-Exposurc Chamber Studies
of Air Pollutant Human Health Effects
Beverly E. Tilton,* Joseph J. Bufalini,' Sarah A. Meeks,1 and Rruce W. Gay'
~Environmental Criteria and Assessment Office; +Atmospheric Research and Exposure Assessment
Laboratory; U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711
ABSTRACT
Air sampling experiments were done in 1985, 1987, and 1993 at the human exposure chamber
facilities of the U.S. EPA Health Effects Research Laboratory in Chapel Hill, NC. Measurements of
VOCs by GC-FID and aldehyde measurements by tlie DNPH silica gel cartridge method were made,
comparing levels at the outside air intake to levels in the human controlled-exposure chamber. Ambient
air passed through activated-charcoal filters can contain varying residual amounts of water vapor and
gaseous pollutants such as hydrocarbons, oxygenates, and other organic and inorganic species. When
the charcoal-filtered air stream is exposed to high-intensity radiation to generate ozone for use in human
controlled-exposure experiments, there may be formation of compounds other than ozone. In this study,
filtration appeared ineffective in removing hydrocarbons; and with ozonation of the airstream. carbonyl
compounds increased.
INTRODUCTION
The current National Ambient Air quality Standard (NAAQS) for ozone is based upon data from
controlled exposures of experimental animals and human volunteers and from various types of
population exposure studies. Controlled exposures of human volunteers in specially designed chambers
have provided key data for the health risk assessment contributing heavily to the basis for the current
primary, health based ozone standard (1,2). In particular, findings from three controlled exposure
studies (3-5) of human volunteers provided important scientific evidence on human health effects- used
by the U.S. Environmental Protection Agency in its 1993 decision on the ozone NAAQS (2,6).
Public comments received by EPA during the most recent review (1986 through 1993) of the ozone
NAAQS included questions regarding the possible formation of chemically or biologically reactive
species during the generation of ozone for human controlled exposures. In brief, the central questions
posed concerned the level of nonmcthanc hydrocarbons in the ambient air stream sent to the ozone
generator and the possible formation during ozonation of peroxides or other reactive, irritant pollutants
that could elicit respiratory symptomatic or functional responses in human subjects so exposed.
These questions were regarded by EPA as relevant, particulary since the bulk of the evidence for
human pulmonary function decrements and respiratory symptoms came from studies in which ozonized
ambient air was used for human controlled exposures to ozone. In addition, theoretical considerations
indicated that at the wavelength and intensity of the mercury lamp ozone generator oxygenated
compounds might indeed be produced, depending upon factors that included the level and kind o1
hydrocarbons in the air stream passing through the ozone generator. The availability nearby of the U.S
Environmental Protection Agency's human exposure chamber provided an opportunity for exploring
these questions. The exposure facility is called the Clinical Laboratory for Exposure Assessment o'
Noxious Substances, and will hereafter be referred to by its acronym, CLEANS.
-------
STUDY OBJECTIVES
This study had Three principal, related objectives:
1) To determine the presence or absence in the CI.HANS exposure chamber of air contaminants,
especially contaminants that could conceivably interfere with the results of controlled exposures to
ozone and could potentially produce misleading results.
2) To evaluate the effectiveness of the air train purification system in removing organic compounds
(e.g., NMOCs, carhonyl compounds) from the ambient air streams ozonated and mixed to supply
the exposure chamber.
3) To determine the possible production of reactive species such as peroxides during ozonation of the
ambient air stream.
EXPERIMENTAL DESIGN AND METHODS
The engineering configuration of the EPA CI.HANS facility at Chapel Ilill has previously been
described (7,8). A simplified schematic of the ambient air train and purification systems is shown in
Figure 1. Outside air (1200 cfm) is prefiltered; passed through a bed of activated charcoal (-45 lb of
6- to 12-mesh activated charcoal in a 1-inch-thick bed); dried to about 9% RH by passage through a
spray of chilled lithium chloride brine: and then passed through HFPA (high-efficiency particulate)
Filters. (Lithium chromate is used to keep the dehydrating brine clean.)
The purified air stream is then split into two, with 200 cfm going to the ozone generator and
1000 cfm to a steam rehumidifier. Tlic.se two streams arc rccombined, post-ozonation, with 6800 cfin
of recirculated air before entering the exposure chamber. The resulting air stream (8000 cfm) exits the
chamber, is filtered a second time, and is split again, with 1200 cfm being exhausted through a roof
vent and 6800 returning to the chamber air train.
Ozone generation is achieved by irradiation of the purified air stream (200 cfm) with low-pressure
mercury lamps. Mercury lamp ozonators produce Oj by direct photodissociation of 02 at 185 nm.
However, water vapor also absorbs at 185 nm (9, as cited in 8), producing OH radicals; and significant
levels of OH radicals are also produced by the reaction of excited O atoms with water. It has been
calculated that steady-state levels of OH radicals in the ozonator ill the CLEANS air train greatly exceed
ambient concentrations (8).
The study repotted here was designed to compare indoor and outdoor concentrations of total
iioninethane organic compounds, peroxides, and carbonyl compounds, to determine the effectiveness
of filtration in removing contaminants from the air .stream used to supply the EPA CLEANS human
exposure chamber. The study was also designed to compare ozonated and non-ozonatcd chamber air
to determine the effects of ozonation on peroxides, carbonyl compounds, and nonmethane hydrocarbons.
To that end, samples of outdoor air and of chamber air were simultaneously taken without the
generation of ozone (to determine filtration effects) and then with the generation and equilibration to
steady-state chamber levels of pre-selected ozone concentrations (to detemiine the effects of ozonation).
No attempt was made to sample at various points within the air train.
Sampling was conducted on 5 days: 12/17/85, 4/22/87, 6/17/87. 6/23/93, and 12/16/93. At each
sampling session, samples were taken simulaneously of air in the chamber and air entering the outside
air intake duct. Samples were collected within 6 inches of (he intake port outside the building and at
central points in the chamber that approximated nose-eye level of human experimental subjects (none
present during these sampling experiments). The first, paired indoor-outdoor samples were taken with
non ozonated chamber air. Subsequent paired samples were taken at predetermined, equilibrated levels
L>f ozone in the chamber.
Samples were collected into stainless steel spherical canisters, using metal bellows pumps (12/17/85
md 4/22/87). with special low-level sampling equipment (from R. Rasmussen; 6/23/93), or with
;vacuated stainless steel canisters fitted with calibrated needle valves (6/17/87 and 12/16/93). Sampling
ines were 3/16-ineh i.d., 2-meter long FEP Teflon.
-------
Samples for NMOC analysis were collected over 10 minutes on 12/17/85 (zero and 400 ppb ozone
in chamber) and on 12'16/93 (zero, or 120, or 250 ppb ozone in chamber). On all other sampling days,
integrated 1-hour samples were collected. Peroxides were measured by the luminol method of Kok
et al. (10). Carbonyl compounds were collected and analyzed using a DNPH-coated silica gel
cartridge,'HPI.C method (11) and, on one sampling day (12/16/93), a DNPH-acetonitrile impinger
collection method (12) was also used to verify cartridge measurements of formaldehyde. Sampling
times for the carbonyl compounds were a minimum of 20 minutes (longer on the first sampling day,
12/17/85). Nonmethane hydrocarbons were measured by the GC-FID speciation method previously
described by Seila et al. (13).
Except for ozone levels, chamber conditions were consistent across sampling days. Chamber air
was maintained at 22°C and 40% RH throughout the study. Outdoor conditions varied by season and
time of day, as well as with vehicle traffic and activity oulside the building. Between the 1987 and
1993 experiments, the air train intake port was moved from the side of the building (2 meters above
tlie ground) to the roof of the one-story building.
RKSULTS AM) lMSCUSS'ON
As indicated in Figure 2, filtration is not particularly effective It should be emphasized that, as
described earlier, the air train used to supply the exposure chambers not only uses fresh ambient air but
also uses recirculated air. This recirculated air, plus Che possibility of some breakout from the charcoal
bed. probably accounts for the presence in the chamber at zero ozone concentrations of NMOC and
carbonyl levels in excess of those seen in ambient intake air.
Concentrations of NMOCs in the chamber in the presence of ozone were in some cases, but not all,
lower than those in outdoor air. Where NMOCs were in excess in the chamber over and above outdoor
concentrations, the differential was less in ozonated chamber air than in zero ozone chamber air. This
is consistent with findings of the Rancho Los Amigos research group in Downey, CA (Ollison, 1985).
Peroxides were increased in chamber air, but did not occur at high levels even al the highest ozone
concentrations generated (400 and 500 ppb). For this reason, peroxide concentrations were not
measured on the 1993 sampling days, when lower ozone concentrations were used. No detectable
hydrogen peroxide was found in chamber air in the absence of ozone. The following levels of hydrogen
peroxide and organic peroxides were found at the respective levels of ozone generated: (1) At 250 ppb
ozone, 3.4 ppb H202 and 0.14 ppb organic peroxide; (2) at 400 ppb ozone, 3 ppb and 4 ppb H,0, for
two separate samples (organic peroxide not measured): and (3) at 500 ppb ozone, 5 ppb H-^Oj and
0.8 ppb organic peroxide. In these three separate experiments, no hydrogen peroxide or organic
peroxide was detected in outside ambient air samples. In a fourth, <1 ppb was detected in
outside air.
The most notable finding of the study is the production of carbonyl compounds during the
generation of ozone. Figure 3 shows changes in carbonyl compound concentrations in chamber air as
a function of the ozone concentration. Although specific points within the air train were not sampled,
theory supports the production of these carbonyl compounds at the ozone generator, as well as th«
possible titration of olefins by ozone, with subsequent cleavage and oxidation. Because of the know
chamber conditions- lighting, air exchange rates, etc.—the observed increases in carbonyl compound;
in the ozonated air stream are postulated to result from reactions in the mercury-lamp ozone generator
Given the lack of close correspondence between NMOC concentrations and carbonyl concentrations i
appears (1) that carbonyl production is not carbon-limited, that is, it is not dependent on NMOC
concentration under the conditions of this study; and (2) that carbonyl production is liighly dependen
on the ozone concentration being produced by the ozonator.
As the filtration data show, there was a trend for less removal of carbonyl compounds and light
molecular-weight NMOCs by the air train purification system. One might expect from those data ths
carbonyl concentrations in the chamber would fluctuate randomly if they were the result of intake i
ambient air and possible slow buildup from recirculation of ambient air. However, the increase w?
806
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consistently related to the level of ozone being generated. This also implies the destruction within the
air train of previously formed carbonyl compounds, but not by filtration, as the filtration data indicate.
The atmosphere in and near the ozone generator is dynamic and may result in photodegradation of
existing compounds while also producing new compounds.
It should be emphasized that the concentrations of carbonyl compounds observed in this study may
represent the lower bounds of possible production during ozonation. This is indicated by the finding
of Arnts and Tejada (14) that ozone is a negative interference in the DNPH-silica ge! cartridge method
for collecting and analyzing carbonyl compounds. Note that no ozone denuder/scrubber was used in
these experiments; the Arnts and Tejada paper appeared after most of the sampling and analyses had
occurred.
CONCLUSIONS AND RECOMMENDATIONS
The ozonation of ambient air to supply the atmosphere for controlled ozone exposures of human
volunteers has been shown to result in the disappearance, though inconsistent, of carbon from
hydrocarbons in the air stream and a consistent increase in carbonyl compounds, along with the
production of an insignificant amount of peroxides. While this study was not extensive enough to
permit carbon balance studies or modeling of the kinetics involved, the qualitative trends toward
decreased hydrocarbons and increased carbonyls are clear. Whether the carbonyl compounds occur in
sufficiently high concentrations to affect any of the results obtained from controlled exposures to ozone
over the range of 120 to 500 ppb ozone in CLEANS or in similar exposure facilities is a question to
be examined by the health researchers. The occurrence, however, of carbonyl compounds as the result
of ozonation of ambient air indicates that careful engineering design and quality control measures should
be observed in all human and animal exposure chambers, including an examination of the composition
and chemistry of the atmospheres introduced into the exposure chambers.
Options for preventing the formation of unwanted contaminants during generation of ozone
atmospheres include the use of a more efficient ozone generator (e.g., silent discharge) and the use of
clean tank air or oxygen for ozonation and subsequent mixing with an ambient air stream to supply the
exposure chamber with ozonated air. Other steps, such as high-temperature combustion, prior to
ozonation, could also be taken for preventing the inadvertent production of carbonyl compounds and
even more reactive compounds such as the peroxides.
Finally, it should be pointed out that EPA has built a new controlled-exposure facility and the
CI,HANS exposure chambers will no longer be used once the new facility is fully operational.
ACKNOWLEDGMENTS
The authors gratefully acknowledge the impetus for this study provided by Dr. Will Ollison,
American Petroleum Institute, and helpful discussions with Dr. Ollison. In addition, the authors
gratefully acknowledge the timely and capable technical assistance of Dr. Silvestre Tejada, U.S. EPA,
for carbonyl analyses, and of Mr. Robert L. Seila, U.S. EPA, and Mrs. Amalia Alexoudis, ManTech
Environmental, for sampling assistance. Dr. Timothy R. Gerrity, Chief, Clinical Research Branch.
U.S. EPA, and staff of the CLEANS facility are gratefully acknowledged for their helpfulness and
:ooperation during this study.
DISCLAIMER
This paper has been reviewed in accordance with the U.S. Environmental Protection Agency's
icer-review and administrative policy and approved for presentation. Mention of trade names of
ommercial products does not constitute endorsement or recommendation for use.
807
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REFERENCES
1. Environmental Criteria and Assessment Office. Air Quality Criteria for Ozone and Other Photochemical Oxidants.
Vol. 2, LPA-6iX)-8-8'--O20t>F, U.S Environmental Protection Agency: Research Tiianclc Park, I98(i; Chantei 10.
2. Office of Air Quality Planning and Standards. Review of the National Ambient Air Quality Standards for Oione
Assessment of Scientific and Technical Information: OAQPS Staff Paper, F.PA-450-8 8S-105A; U.S. Environmental
Protection Agency; Research Triangle Park, 1992.
3. McDonnell, W.F.: Ilorstman, D.ll.; Hazucha. M.J.; Seal, E., Jr.; Haak, E.D.; Salaam, S.; House, D. F„ J. A->rI.
Physiol: Respir. Environ. F.xercise Physiol. 1983 51. 1345-1352.
4. Avol, F..L ; I.inn. W.S.; Ver.et, T.G.; Slip.-non, D.A.; Hackney, J.D. J. Air.Pollyt jConn;oj_ Assoc. 1983 34, 804 809.
5. Kullc, T.J.: Sander. L.R.; Hebe!, J.R.; Chatham, C.D. Am. Rev. Respir. j>is,71985 .132, 36-41.
6. U.S. Environmental Protection Agency. Fed, Reg, 1993 5§, 13008-13019.
7. Strong, A. A. Description of the CI.EAS'S Human Exposure System, EPA-fiOO-1-78-004; U.S. Environmental Protection
Agency: Research Triangle Park, 1978.
8. Ollison, W., American Petroleum Institute, Washington, DC; attachment to Walters. A., personal communication to
Dr. Morion Lippman, CASAC/SAB. U.S. Environmental Protection Agency, 1985.
9. Haulcli, D.L.: Cox. R.A.; Crutzen, P.J.; Hampson, R.F.; Kerr, J.A.; Tore, J.; Watson, R.T. J._Phvs^Chem_Ref.
Data. 1982 11, 327. Cited m Ollison, W.
10. Kok, G.L.; Holler, T.P.; Lopez, M G.; Nachirieb. H.A.; Yuan, M. Environ. Sci. Technol. 1978 12, 1072-1076.
11. Tejada, S B. tot. J. Environ. Anal. Chem. 1986 26, 167-185.
12. Kuntz, R.; Lonneman, W„- Namie, G.; Hull, L.A. Anal...Ixu, 1980 ]3. 1409-1415.
13. Scila, R.L.; Lonneman, W.A.; Mceks, S.A. Determination of C-2 to C-I2 Ambient Air Hydrocarbons in 39 U.S. Cities
from 1984 through 1986. EPA-600-3-89-058: U.S. Environmental Protection Agency: Research Triangle Park, 1989.
Appendix B.
14. Anils, R.R.: Tejada, S B F..nyiron_ Sci_ Techno) 1989 23, 1428 1-130.
^3
Outside
Air
Flow Rate, cfm
f
200
1
1,000
2
1,200
3
6,800
4
8,000
5
| Aerosol
j Gen. / Delivery
X
PF
Heating and
Coollrtg
Control
Damper
Heating
[Rehumldlflerj
lorni
HER R
Exhaust
Charcoal
HEPK
Purge
Damper
Diluting Air
ecu
Non-03
Gas
Supply
Pollutant
Delivery
Control
Exposure
Chambers
Bypass
Control
Damper
Air Flow Sensor
Figure 1. CLEANS air supply system (simplified schematic).
SOS
-------
J= Range
Total
NMOC,
ppb C
C2-C5
NMOC,
ppb C
Total
Carbonyl,
ppb Compound
Figure 2. Effects of activated charcoal filtration of ambient and recirculated air on concentrations of
total and light NMOCs and carbonyl compounds in a human exposure chamber. Comparison
is between outside air samples and chamber air samples that were not ozonated.
• A Carbonyl
Chamber 03 Concentration, ppb
igure 3. Chamber carbonyl concentration as a function of chamber 03 concentration, where
Acarbony) is ([C=0] at [OjJX)) - ([C=0] at [O3]=0).
809
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THE U.S. EPA/ORD LARGE BUILDINGS STUDY
Results of the Initial Survey of Randomly Selected GSA Buildings
Roy Iortmann and Russ Clayton
P.O. Box 13109
Acurex Environmental Corporation
Research Triangle Park, NC 27709
and
V. Ross Ilighsmith and C.J. Nelson
Atmospheric Research and Exposure Assessment Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park. NC 27711
ABSTRACT
The Atmospheric Research and Exposure Assessment Laboratory (AREAL), Office of Research
and Development (ORD), U.S. Environmental Protection Agency (EPA), is initiating a research
program to collect fundamental information on the key parameters and factors that influence indoor
air quality and comfort in randomly selected General Services Administration (GSA) owned and
operated large office buildings. A standardized week-long investigative protocol will be employed
in each building a minimum of three times during different seasons over the next 3-5 years to
characterize the key physical parameters of the selected GSA buildings and randomly selected test
areas; measure key comfort and environmental parameters inside and outside the building:
characterize the heating, ventilating, and air conditioning (HVAC) system(s); and collect occupant
response data associated with their perceptions of indoor air quality.
An initial set of forty GSA office buildings was selected using a stratified random sampling
strategy and a probability proportional to the total number of GSA occupants. The building
managers of the selected buildings were contacted and then the buildings visited to verify their
eligibility for inclusion in the program. Information on the building and potential test areas was als
collected. The selected GSA buildings range in age from two to 80 years old. the size from 3172
nr (34,140 ft:) to 198.775 trr (2,140,000 ft:), and the number of occupants from 46 to 8000. The
buildings are highly diverse with respect to design, floor plans, office layout, furnishings, density c
workstations, and ventilation systems. Although most of the buildings are mechanically ventilated,
some are naturally ventilated including one 33,340 nr building.
This presentation provides a brief overview of the EPA/ORD Large Buildings Study and
objectives, including the study design, measurement parameters, and measurement protocol. The
initial survey results are presented to show the diversity of the randomly selected GSA study
buildings.
810
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DISCLAIMER
Tlit information in this document lias been funded wholly or in part by the U.S. Environmental
Protection Agency. It has been subjected to Agency review and approved for publication. Mention
of trade names or commercial products does not constitute endorsement or recommendation for use.
INTRODUCTION
The Atmospheric Research Exposure Assessment Laboratory (AREAL), Office of Research and
Development (ORD), U.S. Environmental Protection Agency (EPA), is planning to conduct a series
of longitudinal indoor air investigations in selected General Services Administration (GSA) owned
and operated buildings located across the U.S. over the next 3-5 years. The study results, when
combined with the results of the parallel, but cross sectional, EPA Buildings Assessment, Survey,
and Evaluation (BASE) study, will provide EPA and the indoor air research community with a set of
consistently collected, high quality indoor data to evaluate spatial and temporal variability and
identify the status and trends for key parameters influencing indoor air quality and occupant
perceptions of comfort and health. The primary objectives of the combined EPA projects arc to:
• Consistently collect a representative set of key physical, comfort, environmental, and
human-response data that contribute to the indoor air quality in large office buildings and
other important inicroenvironments.
• Survey the temporal and spatial variability of those certain parameters known to be
associated with indoor air quality and occupant comfort and health.
• Provide high quality data, collected using standardized procedures, to the indoor air
research community for assessing the results of their studies and developing new indoor air
research hypotheses.
• Identify the critical factors associated with and distinguish complaint and non-complaint
buildings.
• Validate new methods and protocols for investigating indoor air quality in large office
buildings and other key indoor rnicrocnvironments.
JESCRIPTION OF THE PROGRAM
The EPA/ORD I-arge Buildings Study activities include:
1. An initial set of 40 GSA owned and operated office buildings was selected from the
available GSA office buildings. The GSA buildings were first divided into the 10 EPA
regions and the greater District of Columbia (Maryland, Virginia, and DC). Initial
information was collected to verify that the buildings were office buildings, were available,
811
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and had a sufficient number of occupants to be eligible for the study. The number of
buildings to be investigated in each of the 1! areas was established as follows:
a. A minimum of two buildings would be selected in each area.
b. The actual number of buildings for each area was then determined using the
proportional number of GSA employees in that area compared with the total number
of GSA employees in all the available GSA buildings.
c. The final number of buildings were then rounded to a total of 40 buildings.
Once the number of buildings for each area was established, the buildings to be
investigated were randomly selected from the available buildings within that area.
2. Each selected building was visited and characterized in terms of location, physical
structure, furnishings, ventilation, occupant activities, and potential indoor pollutant
sources.
3. All the potential study areas within each building were defined using the following criteria:
a minimum of 25 occupants contained on a maximum of two floors served by a maximum
of three air handlers. One primary and two replacement study area(s) were randomly
selected. Within the selected study area(s), locations for taking physical and chemical
measurements were also identified and randomly selected.
4. A week-long investigation will be performed in the study area(s) to generate data on
HVAC operation, environmental pollutants, and comfort factors. All building
characterization and monitoring will be performed using standard procedures. Standard
measurement and strict quality assurance and quality control (QA'QC) procedures will be
used to ensure that high quality and comparable data are consistently collected.
5. Occupants in the study area(s) will be surveyed on perceived indoor air quality and healtl
symptoms using a self-administered questionnaire at the end of the week of field
monitoring.
6. Data from each building will be entered into an easily accessible, user- friendly EPA
database.
Tabic 1 summarizes the status of the major program activities, [nitia! survey visits, the first
activity after building selection, have been completed for the first set of 40 GSA buildings.
Additional activities associated with the building and HVAC characterization as well as the comfo
and environmental monitoring will be performed during a one-week period. These activities will
begin with a building walk-through and equipment preparation on Monday and conclude with
packing and shipment of equipment and samples on Friday. The occupant questionnaire will be
administered to the study area(s) participants on Thursday during the week monitoring is conduct
812
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Data collection will be performed using standardized protocols and standard operating
procedures. The EPA Large Buildings Studies Integrated Protocol (dated February 1, 1994)
contains specific procedures to be used for the study area(s) selection, monitoring location(s)
selection, building and study area characterization, environmental and comfort measurements,
HVAC measurements, survey administration, data reduction, and data validation.
In most buildings, environmental and comfort monitoring will be performed in 3-10 locations
within a single study area. In a limited number of buildings, a second study area will be studied to
assess intra-buildiug variability. Table 2 summarizes the measurement parameters, the number of
locations, and (he week-long investigation schedule. A minimum of three randomly-selected indoor
locations will be established for the collection of integrated environmental samples and the
continuous monitoring of selected contaminants and parameters on Wednesday. A series of real
time measurements will be made using portable monitors at these three sites and up ro seven
additional randomly-selected indoor sites during selected times in the morning and afternoon on
Wednesday and Thursday. Comparable ambient sample sets will be collected at a site located in
close proximity to the outdoor air intake for the test area(s). Duplicate samples will be collected
outdoors and at one indoor site.
Selected ventilation measurements (Table 2) will also be made in the test area and in the aLr
handler(s) serving the test area on Tuesday. During the Wednesday and Thursday mobile
monitoring periods, selected HVAC supply, return, and outdoor air supply parameters will be
measured to characterize the air flows and estimate the amount of outdoor air being supplied to the
test area during the monitoring periods.
On Thursday, the EPA Indoor Environmental Quality Questionnaire will be administered to all
occupants in the test area(s) to collect information about the occupants' workplace, their health and
well being, workplace conditions, and job characteristics.
The building data will be processed, reviewed, validated, and placed into a standardized
•'ormat. The validated data will be published in peer-reviewed journal articles and F,PA reporrs and
nput into a publicly accessible EPA database.
CHARACTERISTICS OF THE BUILDINGS SELECTED FOR THE STUDY
The GSA buildings initially selected and surveyed for the EPA'ORD Large Building Study are
xated in 23 different states throughout the U.S. and DC, with eight of the forty buildings located
l DC. The buildings are located in small urban areas (population 100,(XX) or less') as well as large
letropolitan areas (population > 1,000,000). The geographic regions, which represent a wide range
f climates, include the Northeast (Massachusetts), Southeast (Tennessee. Florida). Midwest (Iowa,
Jinois, Indiana), West (California), Northwest (Oregon), and Southwest (Texas).
The selected GSA buildings range in age from two years to 80 years old. Sixteen of the forty
jildings were constructed prior to 1960 and 22 were constructed between I960 and 1975.
[though detailed data were not collected on renovations and modifications to the HVAC system(s)
81?
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since construction, it is known that the HVACs have been modified in a number of these buildings.
In almost all of the buildings, particularly the older buildings, there have been extensive renovations
of the office space since construction.
Many of the buildings in the study are large. The gross square footage of the buildings ranges
from 3,172 nr to 198,775 mJ (34,140 ft- to 2,140,000 ft:) and 24 of the 40 buildings have a gross
floor area greater than 28,000 m1 (300,000 ft3). The occupied area of the buildings ranges from
1,645 nr to ) 12,029 nr. Although building managers could not always provide accurate counts of
the number of workers in the buildings, the estimated occupancy ranges from 46 to 8000. Based on
the information provided for the occupied area and the number of occupants, the area per occupant
would range from approximately 9 nr per occupant (100 fr/occupant) to 56 nr per occupant (600
ftVoccupant) with an average 23 nr per occupant.
The building shape and number of floors varies dramatically for the 40 GSA buildings. The
number of floors ranges from one to 33. with the gross square footage per floor ranging from 8.00C
to 375,000 ft'. Not all buildings had basements, but many had both a basement and subhasement
which covered all or part of the building footprint. Basement parking garages were present in a
number of buildings. In some cases, the buildings have been converted to office space although
designed for a different use. One building was once a hospital, at least two are converted
warehouses, and one was a converted ammunition plant. The office layout and the furnishings in
these buildings is also highly diverse. Office layouts represented in the buildings include individual
offices, bays of interconnected offices, small open spaces with systems furnishings or partitions, an
large (whole floor) open spaces with systems furnishings. Open office space, with no partitions or
systems furnishings, although rare, was observed at some buildings. The type of office layout, age
and style of the furnishings, and amount of renovated space varies substantially between buildings
and is related to the agency occupying the office space.
There is a wide diversity of ventilation systems in use at the buildings. Many buildings conta
one or more central air handlers with heating and cooling coils and ducted air distribution to suppl
all, or a large portion, of the building. There are also a number of buildings that have small air
handlers that serve individual floors or portions of floors. One 69,800 nr building has 72 air
handlers used only to provide outdoor air to the building. There are constant air volume, variable
air volume, and economizer systems. Fan coil units are present on the perimeter of a number of
buildings. Although steam and hot water are the most common methods for heating, some buildir
have electric baseboard heaters on the perimeter. A number of the older buildings have steam
radiators and window air conditioners. Not all buildings have air handlers for supplying outdoor
to the office spaces. In one older building, the ventilation system has not been used for the past t
years. Two buildings have natural ventilation for cooling; one is a 33,334 nr five story building
California and the other is a 4.560 m2 building in Alaska.
814
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SUMMARY AND CONCLUSIONS
The EPA/ORD Large Buildings Study will collect data to evaluate spatial and temporal
variability and identify the status and trends for key parameters influencing the indoor air quality in
GSA owned and operated large office buildings. A week long investigation will be conducted in
each building to characterize the physical parameters of the building, one or two randomly-selected
test area(s), and the HVAC system(s) servicing the test area(s). Key environmental and comfort
parameters will be monitored indoors, outdoors, and in the HVAC systems during the week using
both real-time and integrative monitoring techniques. A questionnaire will be administered to the
test area occupants to assess their perception of indoor air quality and comfort.
The initial surveys to the initial forty GSA buildings reveal a diversity of the buildings in the
study population. The buildings range in age from two to 80 years. The building size ranges from
3172 m: to 198,775 nr (gross floor area), with occupancy ranging from 46 to 8000 employees. A
wide range of HVAC system types are represented in the building. The office layouts vary, as does
the type and age of the furnishings.
The authors would like to acknowledge Dr. Vivian Mills and the other supporting General
Services Administrative professional staff for their contributions and support. Funding for this
>rogram is provided through EPA's Indoor Air Research Program.
'able 1. Schedule and Status of Program Activities
ACKNOWLEDGEMENT
Activity
Time
Initial Survey Visit
Study Area(s) Selection
Selection of Monitoring Locations
Completed
Completed during initial visit
Completed. Validate during
initial investigation
iuilding Investigation Activities
- Study area(s) verification
- Equipment preparation, set-up, and calibration
- Building and study area(s) characterization
- Environmental and comfort measurements
- HVAC measurements
- Questionnaire Administration
- Equipment take down, packing, and shipment
Monday
Monday - Tuesday
Monday - Thursday
Tuesday - Thursday
Monday - Thursday
Thursday
Thursday - Friday
815
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Table 2. Measurement Parameters. Locations, and Schedule
Real-time Monitoring - Mobile Sites
Real-Time Monitoring - Fixed Sites
(Wed. & Thurs. at 3-10 indoor locations)
(Continuous Tues. through Thurs. at three
- Temperature
indoor and one outdoor location)
- Relative humidity
- Temperature (at four heights)
- CO;
- Relative humidity
- CO
- co2
- Respirable particles
- CO
- Sound level (noise)
- Sound level (noise)
- Illuminance (light)
- Illuminance (light)
Integrated Samples (Wed., nine-hour
Exhaust Fans (All exhaust fans in the test
sample)
area measured on Tuesday and checked for
- PMj. - Nicotine
operating conditions on Wed. and Thurs.)
- PM1C - Bioaerosols
- Air flow rate
- TSP - Biological Agents
- VOCs - Ozone
- Aldehydes - Radon
HVAC Air Handler - Supply Air, Return
HVAC - Test Area Supply Diffusers
Air, and Outdoor Air
(Tues. p.m. - flowrates only for AHU(s)
("nies., a.m.. Wed. and Thurs., a.m. &
supply and all supply diffusers in study area;
p.m.)
Wed. and Thurs., a.m. and p.m. - selected
- Air flow rate
subset near monitoring locations)
- Air temperature
- Air flow rate
- Relative humidity
- Air temperature
- CO,
- Relative humidity
- CO
- CO,
- CO
816
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Large Building Characterization
by. Marc Y. Menetrez,
David C. Sanchez, and
Russell N. Kulp
U.S. EPA
Air and Energy Engineering Research Laboratory
Research Triangle Park, NC 27711
Bobby Pyle,
Ashley Williamson, and
Susan McDonough
Southern Research Institute
P.O. Box 55305
Birmingham, AL 35255-5305
Abstract
Buildings are characterized in this project by examining radon concentrations and indoor
air quality (1AQ) levels as affected by building ventilation dynamics. IAQ data collection
stations (IAQDS), for monitoring and data logging, remote switches (pressure and sail
switches), and a weather station were installed. Measurements of indoor radon, carbon
dioxide (COJ, and particle concentrations; temperature; humidity; indoor to outdoor or
sub-slab pressure differentials; ambient and sub-slab radon concentrations; and outdoor
air intake flow rates were collected. The outdoor air intake was adjusted, and fan cycles
were controlled while tracer gas measurements were taken in all zones and IAQDS data
are processed. Ventilation, infiltration, mixing rates, radon entry, pressure/temperature
convective driving forces, C02 generation/decay concentrations, and IAQ levels were
defined. These dynamic interacting processes characterize the behavior of this and
similar large buildings. The techniques incorporated into the experimental plan are
discussed with project rationale. Results and the discussion of those results are beyond
the limits of this paper.
Introduction
This paper describes a research study undertaken in support of the Florida Standard for
Radon Resistant Construction in Large Footprint Structures (currently under development
by the Florida Department of Community Affairs) '. The project entails an extensive
characterization and parametric assessment study of a single large building with the
purpose of assessing the impact of radon entry on design, construction, and operating
features of the building, particularly, the mechanical subsystems 2,:M.
S' 7
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As part of the study, the response of the structure to a range of heating, ventilating, and
air-conditioning (HVAC) operating conditions will be continuously monitored with the
purpose of determining the optimum HVAC conditions to reduce indoor radon within the
envelope of acceptable operation as regards to energy, comfort, and IAQ impacts on the
structure.
The Polk County Administration Building located in Bartow, Florida, is a publicly owned
building constructed in 1988. The building has 149,000 ft1 (14,000 m2) of floor space
distributed over five floors, and has a permanent occupancy of roughly 300 county
employees and elected officials. HVAC needs are met by 11 air handlers (3 on the first
floor and 2 on each of the other four floors). The building is equipped with a variable
air volume (VAV) distribution system with plenum return, and each air handler is
supplied by a separate outdoor air (OA) intake.
Study Objectives
The building was selected for this study as best representing the research criteria
determined in a workshop review process by the Florida Radon Research Program
(FRRP). These criteria represent specific information needs identified by the FRRP as
important to the development of a definable construction standard for this class of
structure. The study has five main objectives:
1. Determine the effect of HVAC operating cycles (including OA level
These parameters include building pressure, ventilation rate, radon
concentration, and radon entry rate (assuming a well-mixed building). The
results will be determined in the course of a parametric study in which
HVAC parameters such as ventilation air will be systematically varied.
promotes radon entry. In the course of the study, we will monitor subslab
pressure variations with position and HVAC status. (We expect two
superimposed effects, one dependent on position and the time derivative of
the barometric pressure and the other dependent on the HVAC cycle and
possibly outside temperature).
Assess the effect of ground floor pressure balance or imbalance, on radon
entry. If pressures are not found to be unbalanced, we plan to use fire
dampers to partially isolate the return of two distant zones on the first floor.
A pressure differential of -5 Pa will be targeted between near and far zones,
and ventilation rates, and radon concentration and entry will be compared
in the depressurized zones.
818
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4. Monitor the transport of air (and radon) between zone and floors. If
mixing of air appears slow, we will experiment with first floor injection
coupled with build-up monitoring.
5. Assess the effect of building features/faults on response variables. Some of
the features and assessment strategies to be used are: elevators
(monitor shaft bottom for radon and estimate flow induced by car movement
to evaluate a semi quantitative estimate of radon pumping); stairwells
(determine concrete wall isolation of radon entry by monitoring radon as
source); ground floor mechanical rooms (assess as entry locations by
monitoring pressure differential and radon); and visible slab penetrations
(seal and assess effect using either local or whole-building measurements).
Measurements
The 1AQ investigation of the Polk County Administration Building involves a series of
manual measurements and the use of measurement instrumentation operating continuously
and downloading automatically. Manual measurements will be taken as part of both an
initial intensive testing phase and a weekly testing series to evaluate HVAC and building
performance. For continuous measurements, 13 IAQDS will be used, with internal and
remote input sensors. Each IAQDS stores information in an internal microprocessor and
transmits this information by modem. In addition to the IAQDS, air exchange rates,
weather station data, and ambient radon measurements will be recorded.
The IAQDS measurements include indoor radon concentrations, differential pressures,
room temperatures, relative humidities, and carbon dioxide concentrations in several
zones. In addition, percentage operation cycle times for selected air handlers, exhaust
fans, and elevators are obtained via switches; duct air temperature and relative humidity
in selected air handlers are monitored; and a particle counter in a single first floor zone
is monitored to provide indicative measurement of indoor particulate levels. The 13
IAQDS are distributed two per floor on the top four floors, with five stations distributed
in several zones on the first floor. Further discussion of locations and assignments of the
IAQDS (as installed) is beyond the scope of this paper.
Building Selection and Plan Development
The building was located and a survey of radon measurements was taken which indicated
elevated radon (in the 4-15 pCi/L range). A draft study proposal was presented to the
building owners, and approval was obtained. Plans to the building were obtained and
used to guide selection of measurements. Walk-through visits were conducted to confirm
locations of continuous samplers, phone and electrical connection availability, and to
obtain a survey of pressure differences between zones of the structure. Monitoring
equipment was obtained, calibrated, and prepared for installation
810
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A) Installation of Continuous Monitoring Systems
A team installed 13 IAQDS sensors and associated interconnecting wires and tubes. A
weather station was installed and monitored by a Campbell 21X datalogger.
Building features were inspected and modifications made to some
measurement locations in response to on-site conditions.
Several deficiencies in the HVAC installation and operation were noted and
reported to the County Facilities Management Staff. The most significant
of these included: significant supply duct leakage in the attic, areas above
the fifth floor; and a total lack of ventilation (outdoor) air into both second
floor air handlers due to obstruction of OA intakes by building framing
after installation. Repair of these conditions delayed the HVAC
characterization phase.
Walk-through surveys were coordinated for related projects.
B) Characterization of HVAC Systems
In addition to the design survey and survey pressure measurements performed, a certified
HVAC test and balance (TAB) company was contracted to verify and spot-check data
from earlier balance reports of the system. These measurements include:
Monitoring of total flow and trunk line supply flow rates from all air
handlers at full open VAV conditions.
Measurement of supply and outdoor air flow rate at each air handler at four
demand flow conditions (nominally 60, 70, 85, and 100% of capacity) and
at four positions of all operable outdoor air dampers (full open, closed, and
nominally 50 and 75%).
Measurement of exhaust fan flow rates.
C) Installation of Tracer Gas System
Sample lines and a computerized sample injection and gas chromatograph electron capture
detector system were installed, checked, and left in continuous operation. The injection
cycle (SF6) will be set at 4 - 8 injections per day depending on observed decay rates. In
addition, SF6 will be injected into OA intakes to measure OA intake rates.
820
-------
D) Operating Cycles
1: Baseline
With all systems operational, a week of data in the "as found" condition will be obtained,
downloaded, and analyzed. Particular attention will be given to the effects of the
building setback period.
2: Maximum Outdoor Air
All operable outdoor air dampers will be set to their full open position, and a week of
data obtained, downloaded, and analyzed. During this period, the data will be surveyed
frequently for indications of cooling system incapacity to meet the added latent heat load
(inability to maintain set points, or excessive relative humidity in air zones).
3: Minimum Outdoor Air
Operable outdoor air dampers will be set to a condition of low outdoor air consistent with
occupant comfort and IAQ status. The target OA level will be at most 50% of the
baseline outdoor air flow rates. Outdoor air levels will be further reduced, to a level
corresponding to less than 5 cfm (0.00236 m3/s)/person at full building occupancy.
During this period, the data will be surveyed daily, and the outdoor air levels increased
if any of the following signs are observed: C02 levels above twice the baseline level or
1500 ppm; reported occupant discomfort; or any other indication of compromised IAQ.
After the results of conditions 1-3 are obtained, conditions for the final 3 weeks of study
will be finalized. Nominal conditions for these weeks are shown below.
4: Altered First Floor Pressure Balance
During this cycle, the pressure imbalance between first floor zones will be enhanced by
partial obstruction of dampered return sleeves through fire zone walls in plenums above
ceilings.
5: Modified Setback
Depending on observed time-resolved behavior of pressures, temperatures, and relative
humidity during earlier setback periods, an alternate setback cycle will be designed and
tested. Likely components will include:
One hour (rather than 30 min) setback periods.
K21
-------
Reductions of exhaust air flow either continuously (by throttling exhaust
lines) or intermittently (by cycling fans off with air handler setback).
6: Sealed Penetrations to Soil
In the initial walk-through, several locations were discovered with significant pathways
(i.e., several holes greater than 1 in.1 [6.45 cm1} in area) to soil. Some of these
penetrations are in mechanical rooms or other similarly vulnerable locations. At the
beginning of this week, major penetrations will be sealed with a suitable polymeric
compound. Mechanical rooms will be monitored for radon concentrations.
Conclusion
The continuous measurement equipment has been installed and the manual measurements
described above have been initiated. It is anticipated that the completion of all
measurements by the above described procedures will accomplish the project objectives.
This presentation of objectives and methods of accomplishing those objectives is part of
an on-going research project.
References
1) Pugh, T.D., Interim Radon-Resistant Construction Guidelines for Use in Florida -
1989, EPA-600/8-90-062 (NTIS PB90-265349), August 1990.
2) ASHRAE Standard 62-1989. Ventilation for Acceptable Indoor Air Quality. The
American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc.
Atlanta, GA, 1989.
3) Leovic, K. W., A. B. Craig, D. W. Saum. Radon Mitigation in Schools - Part
1. American Society of Heating, Refrigerating, and Air-Conditioning Engineers
(ASHRAE) Journal, Vol. 32, No. 1, pp. 40-45, January 1990.
4) Leovic, K.W., Summary ofEPA's Radon Reduction Research in Schools During
1989-90, EPA-60Q/8-90-072 (NTIS PB91-102038), October 1990,
5) ASHRAE 1989 Handbook. Fundamentals. The American Society of Heating,
Refrigerating, and Air-Conditioning Engineers, Inc. Atlanta, GA, 1989,
6) Parker, J.D., HVAC Systems in the Current Stock of U.S. K-12 Schools,
EPA-600/R-92-125 (NTIS PB92-218338), July 1992.
822
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A Comparison of Sorbcnt Sample Cartridges for the Collection and Analysis
of Volatile Organic Compounds Collected in Large Office Buildings
Jeffrey T. Keever and L'uida Sheldon
Research Triangle Institute
Research Triangle Park, NC 27709
The use of sorbcnt materials for the collection of volatile organic compounds
(VOCs) in ambient air lias been utilized for decades. Both polymeric (i.e., Tenax) and
carbonaceous (i.e., Ambcrsorb, charcoal) sorbents have been used for (he collection of
VOCs. Each material has a unique affinity for various volatile compounds and,
subsequently, arc often selectively employed for the collection of specific classes of
chemicals. In an effort to increase the number of VOCs which can be collected and
analyzed using a single sample cartridge, draft BASE protocols for the collection and
analysis of VOCs using both multi-sorbent sample cartridges have been developed.
The purpose of this study was to compare the performance of Tenax GC and
multisorbent cartridges. A sample collection of VOCs on both Tenax and multisorbent
sample cartridges was conducted in three large office buildings. Both sample types
were analyzed by thermal desorption-gas chromatography/mass spectrometry. Data for
instrument calibration, method blanks, method controls, and estimated method
quantitation limits are presented. The results of the sample analysis for the co-located
cartridges are compared. The agreement between the Tenax and multisorbent methods
is discussed.
Although the research described was funded by the U.S. Hl'A (Contract
68-1)2-0131), it has not been subjected to the required peer and administrative review
and does not reflect the views of the Agency, and no official endorsement should be
inferred.
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MANAGING RESIDENTIAL SOURCES OF INDOOR AIR POLLUTION
Bruce A. Tichcnor (Indoor Air Branch) and
Leslie E. Sparks (Radon Mitigation Branch)
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
ABSTRACT
Sources of indoor air pollutants in residential environments can be managed to reduce
occupant exposures. Techniques for managing indoor air pollution sources include: source
elimination, substitution, modification, and pretreatment, and altering the amount, location, or
time of use. Intelligent source management requires knowledge of the source's emission
characteristics, including chemical composition, emission rates, and decay rates. In addition,
knowledge of outdoor air exchange rates, heating/air-conditioning duct flow rates, and
kitchen/bath exhaust fan flow rates is needed to determine pollutant concentrations. Indoor air
quality (IAQ) models use this information and occupant activity patterns to determine
instantaneous and/or cumulative individual exposure. This paper describes a number of
residential scenarios for various indoor air pollution sources, several air flow conditions, and
typical occupant activity patterns. IAQ model predictions of occupant exposures for these
scenarios are given for selected source management options.
INTRODUCTION
Indoor air pollution, especially due to volatile organic compounds (VOCs), is primarily
caused by emissions from ind(x>r sources. The levels (concentrations) of these pollutants are
affected by many factors, including: 1) the emission characteristics of the source (e.g.,
chemical composition, emission rate, decay rate); 2) the interaction of these emissions with
interior surfaces (e.g., sink adsorption/desorption); 3) dilution and flushing by outdoor air
exchange (assuming unpolluted outdoor air); and 4) processes designed to remove pollutants
(e.g., local ventilation, air cleaners). Occupant exposure to indoor air pollution is a function
of the temporal and spacial distribution of the pollutants coupled with individual activity
patterns.
The purpose of this paper is to explore options for reducing occupant exposure in
residential environments by managing IAQ. The focus is on management of sources, including
selecting high, medium, or low emitting sources. This may be accomplished by source
substitution, modification, pretreatment, or elimination. Source management also includes
selecting the amount used, the time of use, and the location of use. In addition, sources can
be used with various air exchange rates and with or without local ventilation. Finally,
occupant activity patterns ultimately dictate individual exposures.
EXPOSURE SCENARIOS
An IAQ model has been developed to predict occupant exposure to indoor air poilutanl
based on source/sink behavior, ventilation parameters, and occupant activity patterns.' The
mode! was used to predict occupant exposures for several combinations of sources, ventilation
scenarios, and activity patterns.
Residential Environment
A three-room, single-level residential environment was evaluated (see Figure 1). The
forced air heating and cooling system has supply registers in the living area, bedroom, and
bath; the return grill is in the hall. The bath has a separate exhaust fan.
824
-------
Sources
Four typical indoor sources with a wide range of emission rates and decay rates were
selected. The emissions of interest from these sources are VOCs. The sources, except for the
aerosol product, were assumed to have first-order emission rate decay of the form:
ER = ER^e11 <))
where, ER = emission rate at time t (mg/m3h)
HRC = emission rate at time 0 (mg/trrh)
k = first-order decay rate (h":)
t = time (h)
Table 1 describes the sources and provides emission rate information.
Sinks
Interior walls, ceilings, and floors were assumed to behave as indoor sinks exhibiting
Langmuir sink behavior; i.e., at equilibrium:
Or, = Mk„ (2)
where, C = VOC concentration (mg/m3)
k, = adsorption rate (m/h)
M = VOC mass in sink (rng/iir)
kd = desorption rate (h1)
F;or walls, ceilings, and bathroom floors: ka = 0.1 m/h and kd = 0.1 h ". All other floors
ire carpeted: k, = 0.1 m/h and kd = 0.008 h"'. (See Reference 2.)
Dccupant Activity Patterns
The occupant activity patterns for each source are given in Tabic 2.
Ventilation and Air Movement Scenarios
Three separate outdoor air exchange rates were assumed: high = 2 ACH (air changes
er hour); medium = 0.5 ACH; and low = 0.2 ACH. The IAQ model was configured to
istribute the outdoor air proportional to the outside wall area for each room. The outdoor air
as assumed to contain no VOCs.
The heating/air conditioning (HAC) fan distributed the air as follows: 350 m'/li to the
ving area; 150 mVh to the bedroom; and 75 m7h to the bath. All the HAC air (575 rrr'/h)
as recirculated via the hall return. Some air movement was also assumed to occur when the
AC fan was off: 70 mVh between the living area and hall; 30 m3/h between the bedroom
id hall; and 15 m3/h between the bath and hall. An exhaust fan with flow of 24 mVh was
the bathroom.
iPOSURE PARAMETERS
Occupant exposures were calculated for three types of health effects: chronic, acute, and
itation/odor. Chronic health effects are due to cumulative total exposure which was
iculated for each occupant by multiplying the concentration, in milligrams per cubic meter,
the exposure time, in hours. Acute health effects are a function of the maximum
icentration, in milligrams per cubic meter, to which each occupant is exposed. Irritation
1 odor responses occur at threshold levels and were evaluated by determining the length of
ic the occupant is exposed to concentrations exceeding the threshold level. Two
825
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irritation/odor thresholds were used for each source. All sources were assumed lo have a high
irritation/odor threshold of 3 mg/m3 total VOC. For paints and aerosols, a low irritation/odor
threshold of 0.3 mg/nv total VOC was selected. For carpet, the low irritation,'odor threshold
was assumed to be 0.01 mg/m2 total VOC, based on an odor threshold of 1 ppb for 4-
phenylcyclohcxene (4-PC) and assuming two-thirds of the total VOC emission are 4-PC. The
low irritation threshold for furniture/particleboard was set at 0.2 mg/m3 total VOC, based on
an irritation threshold of 0.1 ppm for formaldehyde and assuming two-thirds of the total VOC
emissions are formaldehyde.
PREDICTED OCCUPANT EXPOSURES
1AQ model predictions of occupant exposures over a 30 day period were made for
various combinations of source emission rates, ventilation scenarios (general and local), and
occupant activity patterns. Figure 2 shows the time history of the VOC concentration in the
living area due to emissions from the four sources at medium emission rates, outdoor air
exchange rate = 0.5 ACM, the HAC. fan on, and the bath exhaust fan off. Note that the
total VOC (TVOC) concentrations range from <0.1 to >1000 mg/m3 depending on the source
and time. This plot shows the effect of each source individually, not the combined effect of
all the sources.
Tables 3-6 present the results of 1AQ model analyses of various exposure scenarios
for the three exposure parameters discussed above. Table 3 show how changing the emission
rate affects exposure; Table 4 highlights the effect of occupant activity; Table 5 illustrates the
influence of general ventilation (i.e., dilution and flushing with outdoor air); and Table 6
shows the impact of local ventilation (bath fan) and air movement (HAC fan). Both fans were
assumed to be on or off for the complete 30 day period.
DISCUSSION
An examination of Tables 3 - 6 illustrates that the effectiveness of various 1AQ
management options (e.g., changing emission rates, different occupant activities, and various
ventilation scenarios) is dependent on the exposure parameter of interest. For example,
reducing the emission rate (Table 3) and increasing the air exchange, rate (Table 5) both reduce
total exposure and the maximum concentration, but the duration of exposure to odor and
irritation thresholds may nol change significantly. The results also show how interactions
between various factors can affect exposure. For example. Table 4 shows how product users
(painter and aerosol user) can have exposure to high maximum concentrations due to locations
and times of uses. The strategy of vacating for 1 day during painting can reduce chronic, and
acute exposure by about 80%. Also, the interaction of local ventilation with HAC systems is
shown in Table 6 where the person who does not enter the bath (Full-time 2) is completely
isolated from exposure only if the bath fan is on and the HAC fan is off. These types of
interactions make it necessary to examine the effect of all relevant factors before drawing any
conclusions regarding the effectiveness of IAQ management vis-a-vis exposure.
CONCLUSIONS
Individual exposures lo indoor air pollutants are affected by source emission
characteristics, occupancy patterns, and ventilation scenarios. Source management options that
alter these parameters can dramatically affect exposures. The effectiveness of source
management depends on the type of exposure (i.e., chronic, acute, odor/irritation) reduction
desired. Exposure reduction by local ventilation is strongly affected by general ventilation
system (HAC) operation.
826
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REFERENCES
1. Sparks, L.E., "Modeling indoor concentrations and exposures." In: Sources of Indoor
Air Contaminants - Characterizing Emissions and Health Impacts, Annals of the New
York Academy of Sciences, 1992, Vol. 641, pp 102-111,
2. Sparks, L.E., Tichenor. B.A., White, J.B., Jackson, M.D., "Comparison of data from
ail IAQ test house with predictions of an IAQ computer model," Indoor Air, 1991, 4,
577-592.
Table 1. Sources and emission rate information.
Source
Type
Time, of
Use
Location
Emission
Rate
ER„
(mg/m2h)
k
(h1)
Paint
Fast Decay
8AM-5PM,
All Wails
High
50000
0.5
1st Day
(135 m!)
Medium
20000
0.5
Low
2000
0.5
Carpet
Slow Decay
New on
All Floors,
High
2
0.004
1st Day
Except Bath
Medium
0.2
0.004
(43 rn2)
Low
0.02
0.004
Furniture
Constant*
New on
All Rooms,
High
5
0
1st Day
Except Hail
Medium
0.5
0
(10 nr)
Low
0.05
0
Aerosol
Multiple Use
6AM
Bath
High
5000 mg/use
—
Every Day
Medium
500 mg/use
—
Low
50 mg/use
—
'The emissions are not truly constant, but for the 30 days of the evaluation period the decay
was assumed to be zero.
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Table. 2. Occupant Activity Patterns.
Occupant
Sources
Time (0 - 24 h/day)
Location
t'"uil-time
Paint, Carpet,
0 - 6.5
Bedroom
Furniture. Aerosol
6.5 - 7
Bath
7 - 22
Living Area
22 - 24
Bedroom
Full-lime (2)
Aerosol
0 - 7
Bedroom
7 - 22
Living Area
22 - 24
Bedroom
Part-time
Paint, Carpet,
0 - 6
Bedroom
Furniture,
6 - 6.5
Bath
Aerosol (User)
6.5 - 7.5
Living Area
7.5 - 18
Outdoors
18 - 22
Living Area
22 - 24
Bedroom
Painter
Paint
8 - 12
Living Area
12 - 13
Outdoors (Lunch)
13 - 14
Hall
14 15
Bedroom
15 - 16
Bath
Vacate Painting Day
Paint
0 - 24
Outdoors
(Full-time After)
24 & after
Living Area
828
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Table 3. Effect of Emission Rate on Occupant Exposure (Full-Time Occupant, Medium
Ventilation Rate).
Source
Emission
Rate
Total Expos.
{(mg/m3)h}
Max. Cone.
(mg/m3)
Time > Hi
l/OT* (h)
Time > Lo
l/OT (h)
Paint
High
168,000
14,900
430
720
Medium
68,400
5,440
312
616
Low
6,730
598
66
309
Carpet
High
268
0.97
0
727
Medium
27
0.1
0
623
Low
2.7
0.01
0
0
Furniture/
High
459
0.65
0
726
Particleboard
Medium
46
0.07
0
0
Low
4.6
0.01
0
0
Aerosol
High
1,840
56
106
694
Medium
184
5.6
11
106
Low
18
0.56
0
11
'l/OT = Irritation/Odor Threshold
Table 4. Effect of Occupant Activity Patterns on
Ventilation Rate).
Exposure (Medium Emission
Rate, Medium
Source
Occupant
Total Expos.
|(mg/m3)h}
Max. Cone.
(mg/m3)
Time > Hi
I/OT (h)
Time>Lo
l/OT (h)
Paint
Full-time
68,400
5,440
312
616
Part-time
34,700
6,000
178
354
Painter
22,100
8,480
7
7
Vacate 1 Day
14.200
1.280
296
600
Carpel
Full-time
27
0.1
0
623
Part-time
15
0.1
0
360
Furniture/
Full-time
46
0.07
0
0
Particleboard
Part-time
27
0.07
0
0
Aerosol
Full-time
184
5.6
11
106
Part-time (user)
234
19.9
12
48
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Table 5. Effect of General Ventilation on Exposure (Medium Emission Rate, Full-time
Occupant).
Source
Ventilation
Rate (ACH)
Total Expos.
{(mg/m')h}
Max. Cone.
(mg/m3)
Time > Hi
I/OT (h)
Time > Lo
I/OT (li)
Paint
0.2 (low)
222,000
10,700
684
720
0.5 (medium)
68,400
5,440
312
616
2 (high)
22,300
2,970
64
310
Carpet
0.2 (low)
84
0.26
0
727
0.5 (medium)
27
0.1
0
623
2 (high)
9
0.04
0
333
Furniture/
0.2 (low)
144
0.21
0
499
Particleboard
0.5 (medium)
46
0.07
0
0
2 (high)
15
0.02
0
0
Aerosol
0.2 (low)
602
7.3
18
677
0.5 (medium)
184
5.6
11
106
2 (high)
49
2.9
0
33
Table 6. Effect of Local Ventilation on Exposure to VOCs from Aerosol Product (Medium
Emission Rate, Medium Ventilation Rate).
Bath
Fan
HAC
Fan
Occupant
Total Expos.
{(mg/nr)h}
Max. Cone,
(rag/m')
Time > Hi
I/OT (h)
Time> Lo
I/OT (h)
On
On
Part-lime (user)
211
20
12
48
Full-time 1
144
5
6
93
Full-time 2
119
1.7
0
93
On
Off
Part-time (user)
221
23
12
15
Full-time 1
119
12
12
12
Full-time 2
0
0
0
0
Off
On
Part-time (user)
234
20
12
48
Full-time 1
184
6
11
106
Full time 2
160
2.3
0
106
Off
Off
Part-time (user)
277
27
12
48
Full-time 1
238
15
11
89
Full-time 2
100
1
0
89
830
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Figure 1. Residential Environment
Living Area
(4x7x2.5m)
Bedroom
(3x4x2.5m)
Hall (1x2x2.5m)
Bath
(2x3x2.5m)
Figure 2. TVOC Concentrations - Living Area
_ 10,000
Partjcieboard
1,00 ot\
Carpel
Aeroso
WW1*]}
0.001
100 200 300 400
Time (h)
500 800 700
Medium Ventilation Rate
Medium Emission Rates
831
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RELATIONSHIP AMONG DRAG SLED, PUF ROLLER, AND HAND
PRESS TRANSFER OF PESTICIDE RESIDUES FROM FLOORS
David E. Camann, H. Jac Harding, Paul W. Geno
Southwest Research Institute
P.O. Drawer 28510
San Antonio, Texas 78228-0510
Robert G. Lewis
U. S. Environmental Protection Agency
Research Triangle Park. North Carolina 27711
ABSTRACT
The transfer efficiency of formulated pesticide residues from treated carpets and vinyl flooring was
consistently highest by the drag sled, intermediate by the PUF roller, and lowest by human skin. The
flooring material and the pesticide application method liad major effects on transfer, but the specific
active ingredient had no effect. The mean ± standard deviation of the ratios for 17 data sets were
7.4 ± 2.8 for drag sled/hand press and 3.3 ±2.1 for l'UF roller/hand press. Either mechanical method
can be used to estimate dermal transfer of pesticide residues from recently treated floors.
INTRODUCTION
The Dow drag sled (1) and the Southwest Research Institute polyurethanc foam (PUF) roller (2.) are
dislodgeable sampling methods which were recently developed to estimate the transfer of a chemical
from a contaminated surface to the skin and which perform well (3). This paper reports the results from
two of a series of experiments. The objective was to compare transfers of formulated chlorpvrifos,
pyretlirins, and piperonvl butoxide residues from plush carpet (Experiment 6) and from sheet vinyl
(Experiment 7) obtained by the drag sled and the PUF roller to collocated transfers obtained by presses
of a human hand.
METHODS
Transfer Methods
Relevant characteristics of the methods are compared in Table 1. For the drag sled method, one
pass was made over a 1 m x 7.6 cm strip of flooring by dragging a precleaned dry (4 in.f denim-weave
cloth (supplied by B. Shurdut, Dow Blanco) attached beneath foil under a (3 in.? plywood block on
which an 8-lb weight was mounted to provide a contact pressure of 5,900 Pa through the cloth. For the
PUF roller method, one pass was made over a 1 m x 7.6 cm strip of flooring by rolling a precleaned dry
ring of PUF mounted on an aluminum cylinder, with two stainless steel blocks mounted on the
instrument frame to provide a constant contact pressure of 8000 Pa through the PUF ring. For the hand
press method, a subject made one pass over a cardstock-template-exposed 0.635 m x 7.6 cm strip of
flooring by pressing the soap-and-water-washed palm of one hand for 1 s at a pressure of ca 1 psi
(6,900 Pa) onto each of ten adjoining sections of ilie strip. The subject wiped transferred residues from
his hand using two 2-propanol-moistencd gauze sponges, a procedure shown to quantitatively remove
chlorpyrifos and pvrethrin 1 (4).
Experimental Design
The previously-treated plush nylon carpet in the test room was professionally cleaned prior to
Experiment 6A and new sheet vinyl flooring was installed in the room before Experiment 7. A licensee
pest control applicator treated the test flooring for each experiment according to label directions to
control a light infestation of fleas. An aqueous formulation (0.25% chlorpyrifos, 0.25% piperonvl
butoxide, and 0.025% pyrethrin 1) of Dursban® L.O. (EPA Reg. 62719-55) and Kicker® (EPA Reg.
832
-------
4816-707AA) was applied from a pressurized tank with a fan broadcast nozzle about 4() cm above the
floor at 1 gal/T 6()0 ft2 for Experiments 6A and 7. The applicator sprayed Siphotrol® premise spray
(0.015% methoprene, 1.0% piperonyl butoxide, and 0.2% pyrethrin I) from the aerosol can using a
sweeping motion as a second treatment of tlx; carpet for Experiment 6B. The room was ventilated by
opening doors and windows (with a box fan in the doorway) for 20-30 min and by operating the air
conditioning for 2 h after application to ensure the pesticide residue was dry before sampling
commenced.
For each experiment, adjacent deposition and transfer samples were sequentially collected using two
coupons, the PUF roller, the drag sled, and ten adjoining presses (one press in Exp. 6A) of the same
hand by each of three human subjects within each of six rectangular blocks of treated flooring. Field
blanks of each transfer method were obtained by sampling prior to the application. Field samples were
collected from two blocks after label-permitted re-entry (>2 h after application) on the day of
application, and from two more blocks on both of the succeeding days. Field spikes of each prccleaned
transfer medium were performed both before and after the six blocks of field sampling to assess losses
during transport, storage, and extraction.
Drag cloths and PUF rings were Soxhlet-extracted with 6% ethyl ether/94% hexune. 2-PropanoI-
saturated handwipes were shake-extracted with 1:1 ethyl ethenhexane (4). Extracts were analyzed for
chlorpyrifos, methoprene, piperonyl butoxide, and pyrethrin I on a Fisons MD 800 operating in
selected- ion monitoring mode. Reported data have not been adjusted for field spike recoveries.
RESULTS AM) DISCUSSION
Recovery of target analytes in field spikes of the sampling media was essentially quantitative
(Table 2). Methoprene, piperonyl butoxide, and pyrethrin I were not detected in any of 42 hand press/
2-propanol wipe field blanks. However, chlorpyrifos was found in 41 of 42 hand press/2-propanol wipe
field blanks, at mean levels of 0.18 pg and 0.26 (jg after single presses onto aluminum foil and carpet,
and of 0.23 pg after ten presses along clean cardstock, respectively (Table 3). The absence of
chlorpyrifos in 2-propanol-gauze laboratory matrix blanks indicates that the chlorpyrifos was wiped
from the subjects' hands, but its source is unclear. Each subject washed his hands with soap and water
before performing each hand press. One possibility is transfer from a chlorpyrifos-contaminated object,
such as the faucet handle or soap bar, during handwashing. More likely is removal by the more
vigorous 2-propanol-wipe of clilorpyrifos in fats and oils deeply embedded in the skin, which were not
removed by the soap-and-water wash.
Table 4 presents the data on loading and rate of transfer by the three methods for a typical active
ingredient and experiment, piperonyl butoxide in Exp. 6B. A comparison of the transfer rates of the
three methods is given in Table 5 by active ingredient within experiment. The transfer rates of every
active ingredient from both flooring materials were consistently highest for the drag sled, intermediate
for the PUF roller, and lowest (when measurable) for the human hand press. The frequent high
variability in transfer observed for some methods and flooring was also observed for deposition
coupons; it largely reflects non-uniform deposition during applications, where the professional
applicator glanced over his shoulder to avoid stepping on the coupons.
The efficiency of transfer of the three methods relative to surface loading is shown in Table 6. Each
nethod simultaneously transfers all applied active ingredients with virtually the same efficiency from
he treated flooring (i.e., percent mean transfer is within a factor of two). In contrast, transfers from
;heet vinyl are one to several orders of magnitude greater than transfers from plush carpet. For a given
nethod, transfers after broadcast application were 100- to 300-fold greater from sheet vinyl than from
ilush carpet. Transfers from plush carpet were 20 to 30-fold greater after aerosol can application than
fter broadcast application.
Tabic 6 indicates that the transfer efficiency is about three times higher for the drag sled than for the
'UF roller, and about three times higher for the PUF roller than for the hand press, for ever}' active
tgredient. flooring, and application method investigated. To obtain a more precise estimate of this
:lationship, the ratio of the mechanical method transfer mean (n=2) to the simultaneous hand press
833
-------
transfer mean (n=6) was calculated for the 17 specific sets of pesticide within day within experiment.
Both the drag sled/hand press ratio and the PUF roller/hand press ratio were quite stable over the broad
range of transfers in these 17 sets. The mean ± standard deviation of the ratios were 7,4 ± 2.8 tor drag
sled/hand press and 3.3 ± 2.1 for PUF roller/hand press.
These observations indicate that the PUF roller and the drag sled can both be used to estimate
transfers of formulated pesticide residues from flooring to a human hand by press contact. Crude
estimates of the transfer to human skin of residues of pesticides recently applied to a floor surface can
be obtained from drag sled or PUF roller measurements of the surface, using the mean transfer ratios
given above.
ACKNOWLEDGEMENT
This research was funded by the U.S. Environmental Protection Agency (Contract 68-DO-0007)
under subcontract from Battelle. This paper has received EPA's peer and administrative review, but no
official endorsement should be inferred.
REFERENCES
1. Vaccaro, J R.. Cranston. R.J, "Evaluation of dislodgeable residues and absorbed doses of
chlorpyrifos following indoor broadcast applications of chlorpyrifos-based emulsifiable concentrate.
Internal Report, Dow Chemical Co., Midland. Ml, 1990.
2. Hsu, J.P., Camann, D.E., Schattenberg, H.J. et al., "New dermal exposure sampling technique," in
Proceedings of the 1990 U.S. EPA/A&WMA International Symposium on Measurement of Toxic and
Related Air Pollutants. VIP-17; Air & Waste Management Association, Pittsburgh, 1990; pp 489-
497.
3. Camann, D.li., Harding, H.J.. Agrawal, S.R., Lewis, R.G. "Comparison of transfer of surface
chlorpyrifos residues from carpet by three dislodgeable residue methods," in Proceedings of the
1993 U.S. EPA/A&WMA International Symposium on Measurement of Toxic and Related Air
Pollutants . VIP-34; Air & Waste Management Association, Pittsburgh, 1993, pp 848-856.
4. Geno, P.W., Camann, D.E.. Harding, H.J. et. al., A hand wipe sampling and analysis procedure for
the measurement of dermal contact to pesticides, J. Expos. Anal. Environ. Epidemiol, (submitted)
Table 1. Characteristics of dislodgeable residue and hand press methods
Drag Sled PUF Roller Human Hand Press
Sampling medium
Denim weave cloth
Polyurethane foam
(PUF) ring
Skin on palm of hand
Surface of sampling
medium
Square (10.2 cm)2
Curved exterior of
ring (8.9 x 7.6 cm)
Palm through template
Contact motion
Drag
Roll
Ten presses (for 1 s)
Pressure through
medium
5,900 l'a
8,000 Pa
6,900 Pa
Sampled floor area
7.6 cm x 1.0 m =
760 cm"
7.6 cm x 1.0 m =
760 cm2
10 x 7.6 cm x 6.3 cm =
480 cm'
Number of passes
1
1
1
Sampling speed
7 em's
10 cm/s
Ftach press for 1 s
834
-------
Table 2. Field spike recoveries (%) from sampling
media
Matrix
Analyte
n
Mean
Std. Dev.
Denim drag cloth
Chlorpyrifos
21
113.1
35.3
18:
100.6"
13.91
Mcthoprene
4
125
24
2"
108'
17*
Piperonyl butoxide
5
83
18
Pyretlirin I
7
95
46
6a
111"
21"
PUP ring
Chlorpyrifos
24
101.0
21.1
23 s
103.9"
15.9'
Methoprene
4
112
14
Piperonyl butoxide
6
90
18
Pyrethrin I
8
J17
25
2-Propanol - moistened
Chlorpyrifos
26
85.5
14.9
SOF-WICK® gauze
Methoprene
4
74
14
Piperonyl butoxide
8
108
43
Pyretlirin I
26
114.9
49.1
241
102.91
23.7*
a Apparent outlicr(s) excluded
Table 3. Chlorpyrifos (ng/sample) in field and laboratory 2-propanol hundwipC* blanks
No.
Chlorpyrifos Detected
No. Hand
No.
Subjects Presses*
Pressed Surface
Blanks
n
Mean
Range
Lpb Btanto
0 0
None
3
0
Hvld Blanks
2 1
Aluminum foil
8
8
0.18
0.10-0.38
3 1
Carpet (48 cm')
12
12
0.26
0.14-0.60
3 10c
Cardstock (480 cm7)
22
21
0.23
0.11-0.88
a Two wipes of hand(s) with 2-prcpanoi-moisicned SOF-VVICK3) g&uzc.
b Press of palm of one hand onto cleaned surface.
c Ten presses of palm of one hand onto adjacent sections of clean cardsfock.
-------
Table 4. Transfer rates (ng/cra2) of piperonyl butoxide from plush carpet in Experiment 6B by
drag sled, PUF roller, and human hand presses
Block
Drag
Deposition Sled
PUF
Roller Hand
Ten Hand Presses
A B C
6-22-93 (Application)
NE
NW
6-23-93
CE
CW
6-24-93
SE
SW
Statistics
n
Mean, x
Std. dev., s
Coef. of Variation
4,980
5,810
2,870
2,480
4,120
4,000
6
4,040
1,250
0.31
167
178
160
116
107
39
6
127.9
52.1
0.41
67
75
41
48
61
53
6
57.6
12.5
0.22
R
L
L
R
R
L
12 18
42 39
26 12
19 17
17 13
9 5
18
17.4
9.7
0.56
13
21
10
14
11
16
836
-------
Table 5. Comparison of transfer of fresh dried formulated pesticide residues from flooring by
drag sled, PUF roller, and human hand presses*
Transfer Rate ( x ± s^, ng/cro2. Using
Exp.
Flooring
Applied Active
Ingredient
Drag Sled
(11=6)
PUF Roller
(n=6)
Ten Hand
Presses
(n=18)
6A
Plush carpet
Chlorpyrifos
5.6 ±3.2
O
+1
00
CBde
(used)
Piperonyl butoxide
7.0 ±4.0
2.2 ±1.1
ND",C
Pyrethrin 1
1.0 ±0.9
0.2 ±0.1
NDC
6B
Plush carpet
Chlorpyrifos'
9.2 + 3.7
2.9 ±0.3
1.3 + 0.8
(used)
Methoprene
2.5 ±0.7
0.8 ±0.5
0.3 ± 0.2
Piperonyl butoxide
128 ±52
58 + 12
17+10
Pyrethrin 1
38 ± 22
16 ± 3
ND
7
Sheet vinyl
Chlorpyrifos
1890 ±1430
780 ± 440
250 ± 200
(new)
Piperonyl butoxide
1660 ±990
630 ± 390
300 ±210
Pyrethrin I
192 ±49
116 ±68
39 ±42
a Transfer by single pass over flooring using dry contact medium
h Mean and standard deviation of transfer rates from 0 fo 2 days after nppiicafion
c Transfer rates from 6 to 8 days after application
d Single hand press
e CB •= comparable to field blank; ND = not de'erted
Table 6. Transfer efficiency (%) of fresh dried residues by flooring, active ingredient, and
transfer method*
Transfer Efficiency. %"
Application
Active
Drag
PUF
Ten Hand
Exp.
Flooring
Method
Ingredient
Sled
Roller
Presses
6A
Plush carpet
Broadcast
Chlorpyrifos
0.10
0.03
(used)
Piperonyl butoxide
0.12
0.04
Pyrethrin I
0.19
0.04
6»
Plush carpet
Aerosol can
Methoprene
3.0
1.0
0.4
(used)
Piperonyl butoxide
3.2
1.4
0.4
Pyrethrin I
3.3
1.4
7
Sheet vinyl
Broadcast
Chlorpyrifos
24
9.7
3.2
(new)
Piperonyl butoxide
22
8.3
4.0
Pyrethrin I
16
9.6
3.2
a Transfer efficiency (%) = l(X) x (mean transfer rale, ng/cm* )/;me;.n surface landing, ng/cnf). Means of transfer rates and surface
loadings are for observations from 0 to 2 days af:cr appJica:ion
b Transfer by single pass over flooring using dry contact mediuir.
-------
COMPARISON OF PM25 AND OPEN-FACE INLETS FOR SAMPLING
AEROSOLIZED PESTICIDES ON FILTERED POLYURETHANE FOAM
David E. Camann, H. Jac Harding
Southwest Research Institute
P.O. Drawer 28510
Sari Antonio, Texas 78228-0510
Charles L. Stone
University Research Glassware
Carrboro, North Carolina 27510
Robert G. Lewis
U. S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
ABSTRACT
Ten pairs of air concentrations were obtained using collocated PM- 3 and open-face inlets to collect
aerosolized formulations of neutral pesticides and acid herbicides in wind tunnel experiments. In
sampling the generated aerosol, the PM. 5 inlet measured significantly smaller air concentrations of
chlorpyrifos, 2,4-D, and mecoprop than the standard open-face inlet. In contrast, both inlets determined
similar concentrations of neutral pesticides in ambient air.
INTRODUCTION
In sampling the particles and vapor of an aerosolized pesticide through the standard open-face
inlet (1), a filtered polyurcthane foam (PUF) trap will collect some airborne particles which are too large
to be respired. A portable size-selective impactor inlet for the standard filtered PUF plug enclosed in
sturdy plastic housing has recently been developed to sample vapors and particles of dia. 2.5 |im or less
(PM2 5) for personal monitoring. Wind tunnel experiments were performed to determine if this personal
PUF sampler with a PM:. inlet collects a smaller mean pesticide air concentration than the standard
PUF sampler with an open-face inlet.
METHODS
Air Sampling Methods
Air samples were collected on precleaned PUF with a quartz fiber prefilter using the standard
cartridge with an open-face inlet (1) and the URG-2000-25A cartridge (Figure 1, University Research
Glassware, Carrboro, NC) with a PM2 S inlet. Relevant properties of both cartridge assemblies are
compared in Table 1. Each cartridge was attached by Tygon® tubing to a DuPont Alpha 1® sampler
calibrated at a nominal 3.8 Lpm flow rate, and hung with the inlet facing downward. Air samples were
collected for 16 to 30 min to span the release of aerosolized pesticide, during an experimental run. PUF
plugs were cut and cleaned, Whatman filters were cleaned, and sampling cartridges were assembled and
protected as previously described (2). 50 |iL of diluted Dow Corning 704 high temperature silicone oil
was placed on the impactor frit of the URG cartridge. Aluminum foil was also wrapped around the
URG cartridge and the union connector of the standard cartridge to protect exterior surfaces and avoid
possible transfer contamination of the PUF or filter during set-up for extraction.
Wind Tunnel
A simple outdoor wind tunnel was constructed from large cardboard boxes mounted on sawhorses to
contain an aerosol generator, an air movement system, and four air sampling systems (Figure 2), The
tunnel was oriented parallel to the prevailing wind direction. The fan speed of the box fan was set so
838
-------
that ambient air traversed the tunnel at 2 to 4 ra/s during each experimental run. A burst of aerosolized
pesticide formulation was generated by operating a heavy-duty sprayer for 3 s to release a fine spray in
a cone pattern from the noz/le every 15 s into the airstreara near the tunnel entrance. Two screens were
placed across the tunnel between the nozzle and the air samplers to enhance aerosol mixing and
diffusion. Initial qualitative tests were performed with fluorescent tracers which demonstrated uniform
horizontal dispersion of the aerosolized tracer at the tunnel outlet.
Experimental Design
Ten pairs of air concentrations were obtained using collocated open-face and PM, 5 inlets in each of
two wind tunnel experiments. Each experiment consisted of a preliminary run. a field blank run, and
five replicate field sampling runs. Two inlets of each type were positioned at the opposite corners of a
square with 40-cm sides to collect the air samples for each ran (Figure 2). The two inlets at the same
height were treated as one pair. To prevent possible location bias, the positions of the open-face and
PM2 5 inlets were alternated on successive runs. The preliminary run verified that the quantity of
formulation aerosolized was sufficient to yield detectable sampled air concentrations. The five replicate
runs to sample the aerosolized formulation were performed over three days. 100 mL of Zema Fast
Acting Spray for Dogs® (0.225 % chlorpyrifos, 0.05 % pyrethrins, 0.10 % piperonyl butoxide) in 1.5 L
of deionized water was aerosolized in each run of the neutral insecticide experiment. 100 mL of Ortho
Weed-B-Gon for Southern Lawns Formula II® (10.6 % dimcthylamine [DMA] salt of mecoprop, 3.05 %
DMA salt of 2,4-D, 1.30 % DMA salt of dicamba) in 1.5 I- of deioni/ed water was aerosolized for each
run of tlie acid herbicide experiment. A field spike of the PUF plugs (insecticide experiment) or filters
(herbicide experiment) was placed on both types of sampling cartridges, both before and after the five
replicates.
Analytical Methods
The PDF and filter from each cartridge were extracted together as a single sample. Samples from
the neutral pesticides experiment were Soxhlet-extracted with 6% diethyl ether/94% hexane (3).
Samples from the acid herbicides experiment were cold-shake extracted using acidified 1:1 diethyl
ether:hexane, and the extracts were esterified with diazomethane (3). Extracts were analyzed for
chlorpyrifos, pyrethrin I, and piperonyl butoxide (neutral pesticides experiment) and for the methyl
esters of 2,4-D, dicamba, and mecoprop (acid herbicides experiment) on a Fisons MD 800 operating in
selcctcd-ion monitoring mode.
Statistical Methods
Reported data have not been adjusted for field spike recoveries. The differences between paired
open-face and PM2, air concentrations were evaluated over all ten pairs by a t-test of the null hypothesis
of equal determinations of the pesticide against the one-sided alternative of a smaller determination with
the PM2j inlet at the 0.05 level of significance.
RESULTS AND DISCUSSION
Pyrethrin I and piperonyl butoxide were not detected in the air samples. Reported analytes were
efficiently recovered from field spikes of sampling media (Table 2). Field blanks showed that off-
gassing of dried residues from prior runs was minor compared to aerosols generated for the field
replicates.
The individual measured air concentrations from the ten pairs and their summary statistics are
presented for chlorpyrifos and 2,4-D (Table 3). The PM, 3 Inlet appears to give generally smaller mean
air concentrations than the open-face inlet for each measured aerosolized analyte (Table 4). However,
he validity of three pairs of measurements from the acid herbicide experiment is uncertain. The levels
obtained for 2,4-D, dicamba, and mecoprop in the PM,, inlet sample of the Replicate 4 upper level pair
nay underestimate the actual concentrations because the extract went to partial dryness during blow-
lown. In addition, for all three acid herbicides, the air concentrations from the Replicate 3 upper level
839
-------
pair exhibit a relationship (open-face « PM^) which differs markedly from the other nine pairs, and is
the opposite of the relationship seen in eight other pairs (open-face » PVl,). This suggests a possible
mix-up during labelling or processing of these two samples or their extracts, despite a lack of supporting
evidence. The hypothesized sample mix-up might also have affected the lower pair of Replicate 3. To
be conservative, the statistical analysis was performed both including (n=10) and excluding (n=7) the
pairs with a questionable acid herbicide measurement (Table 4). Significantly smaller air
concentrations of chlorpyrifos, 2,4-D, and mecoprop were sampled with the PM,, inlet than with the
standard open-face inlet in aerosols generated in the wind tunnel experiments. No inference can be
drawn from the dicamba measurements.
Pairs of ambient concentrations of neutral pesticides were also obtained with collocated open-face
and PM15 inlets by sampling ambient outdoor air in an urban area for 24 h as described. Both inlets
gave very similar air concentrations of the prevalent pesticides, chlorpyrifos and lindane, but the PM 5
determination was usually slightly larger (Table 5). Heptachlor was detected more frequently with the
PMj, inlet, while atrazine and 4,4'-DDT were more frequently detected with the open-face inlet. The
open-face and PM;, inlets appear to trap similar concentrations of neutral pesticides from ambient air.
ACKNOWLEDGEMENT
This research was funded by the L.S. Environmental Protection Agency (Contract 68-DO-0007)
under subcontract from Battelle. This paper has received EPA's peer and administrative review, but no
official endorsement should be inferred.
REFERENCES
1. ASTM 4861, "Standard Practice for Sampling and Analysis of Pesticides and Polvchlorinated
Biphenyls in Air", Annual Book of ASTM Standards, Vol. 11.03, American Society for Testing and
Materials, Philadelphia, 1992.
2. Harding, H.J., Merritt, P.M., Clothier, J.M., et al„ "Sample collection methods to assess
environmental exposure to agricultural pesticides," in Proceedings of the 1993 U.S. EPA/A&WMA
International Symposium on Measurement of Toxic and Related Air Pollutants ,"VIP-10; Air &
Waste Management Association; Pittsburgh, 1993; pp 842-847.
3. Geno, P.W., Camann, D.E., Villalobos, K., Lewis, R.G., "Analytical methods for assessing the
exposure of farmers and their families to pesticides," in Proceedings of the 1993 U.S. EPA/A&WMA
International Symposium on Measurement of Toxic and Related Air Pollutants, "VIP-10; Air &
Waste Management Association; Pittsburgh, 1993; pp 698-705.
Table 1. Comparison of properties of cartridge assemblies used for sample collection.
Property
Standard Open-face
Filtered PUF Cartridge
URG PMz i Filtered
PUF Cartridge
Filter size
PUF plug size
Air sample flow rate
Filler type
Impactor disc
Particle size collection
None
All
2500 QAT-UP
(0.5 (im)
32 mm
2.5 cm dia. x 7.6 cm
3.8 Lpm
#30 aluminum insert
<2.5 pm dia.
2500 QAT-UP
(0.5 nm)
25 mm
2.5 cm dia. x 7.6 cm
3.8 Lpm
840
-------
Table 2. Field blank3 amounts and field spike recoveries.
Analyte
Mean (n=4) field
blank amount.
Spike recovery, %
Mean ± std. dev. (n)
Chlorpyrifos
0.02
89 ± 8 (4)
2,4-D
0.005
85 ± 4 (2)
Dicamba
<0.005
88 ± 4 (2)
Mecoprop
0.02
98 ± 6 (2)
Four clean cartridge assemblies operated in the wind tunnel for 20-30 min (3-5 days after a
preliminary run using the aerosolized analyte)
Table 3. Comparison of air concentrations from collocated open-face and PM,5 inlets for chlorpyrifos
and 2,4-D.
Air Concentration, /^g/m3
Chlorpyrifos
2,4-D
Rep-
Inlet
Open-
Open-face
Open-
Open-face
licate
height*
face
I'M,,
-I'M,,
face
PM, s
-I'M,,
1
U
3.6
2.2
1.4
4.8
0.6
4.2
L
3.8
4.4
-0.6
9.0
0.4
8.6
2
U
2.7
2.0
0.7
2.9
0.9
2.0
L
6.9
4.3
2.6
15.0
0.7
14.3
3
U
4.8
2.1
2.7
0.61'
7.21'
-6.6"
L
4.5
1.4
3.1
2.8
0.7
2.1-
4
U
2.2
1.2
1.0
2.0
0.8C
1.2d
L
6.1
2.8
3.3
6.4
0.4
6.0
5
U
3.8
0.7
3.1
2.5
0.3
2.2
L
3.3
1.8
1.5
0.40
0.45
-0.05
n
10
10
10
10. (¥*)
10. (8e)
10. (7)
X
4.16
2.29
1.87
4.64 (5.09'\)
1.23 (0.54')
3.40 (5.34')
s
1.46
1.24
1.30
4.51 (4.53')
2.11 (0.30')
5.54(4.88')
Samples fiom same horizontal plane ate paired: U = upper level. L - lower level.
Possible mix-up of samples by inspection of results for a!! three acidic ar.slvtcs.
Possible underestimate, since sample went to partial dryness during extraction.
Questionable rrst-H; see f'oofnolcs h and c.
Excluding quesnooabie results.
841
-------
Table 4. Summary of tests to determine if PM2 5 inlet collects a smaller mean air concentration of
aerosolized analytes than a collocated open-face inlet.
Air Concentration, (ig/m3
Mean ± Std. Dev. (n) Is PM,, Concentration Smaller?
Open-
Mean
Aerosolized
face
pm25
No.
difference
Significantly
Analyte
Inlet
Inlcl
Pairs
Hg/m!
p-value
smaller'?
Chlorpyrifo
4.2 ±1.5
2.3 + 1.2(10)
10
1.9
0.001
Yes
s
(10)
2,4-D
4.6 ± 4.5
1.2 + 2.1 (10)
10
3.4
0.04
Yes
(10)
7'
5.3
0.015
Yes
Dicamba
1.8 ± 1.4
0.7 + 1.0(10)
10
1.2
0.05
No
(10)
t
2.0
0.01
Yes
Mecoprop
13.8 ± 11.1
4.0 + 7.1(10)
10
9.9
0.04
Yes
(10)
7"
15.7
0.007
Yes
a One-sided t test at a=0 05.
b Excluding pairs with questionable results.
Table 5. Pesticide concentrations in ambient air (ng/irf) determined by collocated open-
face and PMj , inlets.
Chlorpyrifos Lindane
Day
Open-face
PM-
Open-face
PM,,
1
1.3
1.4
<0.4
1.1
2
1.3
0.8
1.0
1.1
3
0.9
0.7
1.0
1.2
5
1.9
0.8
1.2
1.3
6
0.9
1.3
1.2
1.0
8
0.7
1.3
1.2
<0.04
9
1.2
2.5
1.0
1.3
10
0.9
1.1
1.1
1.3
11
0.8
0.9
1.2
1.4
No. larger
3
6
2
7
measurements
842
-------
11
Intel nozzle
Impactor
Te/lon O-rlng
- Fitter paper
- Stainless steet
support amm
-Puf
-Glass put holder
{•;:!! |
«S2*S»» Ofins
v :i: n}\-j B. Top housing
A. Bottom housing
O-rlng
- Outkit vacuum
Figure !. URG-2000-25A, Portable Size - Selective Tmpactor Inlet'with PUF, 4 Lpm, 2.5 ,^m cut
Prevailing
Wind
Dlffuser
AMtLf-,
3
Box Fan spray Nozzle
25"
44"
Hand Sprayer
"with Pesticide
Formulation
42:
Paired Air Samples
from Same
Horizontal Plane
Figure 2. Outdoor wind tunnel system to generate aerosolized pesticide mixture and collect
collocated air samples.
84:?
-------
-------
SESSION 19:
SOURCES AND FATE OF
ATMOSPHERIC VOCS
-------
-------
Methods to Determine the Biogenic Contributions
to Ambient Concentrations of Volatile Organic Compounds
R.K. Stevens, C.W. Lewis, and W.A. Lonneman
U.S. EPA
Research Triangle Park, NC
R.A. Rasmusseii
Oregon Graduate Institute
Beaverton, OR
GA. Klouda
National Institute of Standards and Technology
Gaithersburg, MI")
W. Ellenson
ManTcch Environmental
Research Triangle Park. NC
S.L. Duttner
Texas Air Control Board
Austin. TX
Vegetative emissions of photochemicaliy reactive volatile organic compounds
(VOCs) (e.g., isoprcnc) are considered important sources of ozone precursors. The
U.S. EPA is currently evaluating a number of procedures to obtain reliable biogenic
emission inventories. This report describes ambient measurement procedures to collect,
process and analyze VOC samples to measure the relative percent of the total VOCs
that originates from vegetative emissions. In 1992, VOC' were collected in 32L
canisters at a downtown location in Atlanta as part of the summer Southern Oxidant
Study. These canister samples were to be submitted to the National Institute of
Standards and Technology to measure their ;"C content. Vegetative (also referred to as
biogenic) VOCs are enriched in *4C while emissions from fossil fuels (e.g., gasoline)
arc practically devoid of this isotope. Thus, the ratio of !
-------
is developed. In the mean time, a new pre-cryogcnic procedure has been developed
to reduce the CO, concentration by a factor of 10s (e.g., from 360 ppm to 3(1 ppb) in
whole air samples through the use of a LiOH trapping system. These samples would
then be submitted to NIST for subsequent cryogenic separation of VOCs from CO and
CH.(. followed by oxidation to CO, measurement processing. The identification
and quantification of VOC species lost during the C02 removal step has been
incorporated into the methodology. For example, as part of the procedure an aliquot of
whole air sample, prior to removing the. CO,, is analyzed by identical gas
chromatographic (GC) systems, one equipped with a flame ionization detector (FID)
and the other a mass selective (MS) detector. The GC/FID analyzer quantifies each of
the chromatographic peaks and the GC/MS system identifies each species elutcd from
the GC column. After the CO; has been removed from the whole VOC air sample, it
is reanalyzed by the GC/FID and GC/MS analyzers. In this way, losses of VOCs
(especially oxygenates) may be quantified and identified. Those species which
have been identified as biogenic or biogenic reaction products are incorporated into
estimates of the fraction of VOCs that may originate from biogenic sources. The report
describes the status of these studies and presents preliminary results of the gas
chromatographic analysis and "C measurements.
848
-------
Radiocarbon Measurements Of Wintertime Atmospheric Carbon Monoxide in
Albuquerque, NM: Contributions Of Residential Wood Combustion
George A. Klouda
National Institute of Standards and Technology
Gaithcrsburg, MD 20899
Michael V. Connolly
Albuquerque Environmental Health Department
Albuquerque, NM 87103
In the past during winter months, Albuquerque, NM, has occasionally exceeded
the 9 [iL/L (part-per-million by volume, ppmv) - 8 hour National Ambient Air Quality
Standard (NAAOS) for carbon monoxide (CO), thereby, requiring action toward
attainment. Previous results of CO concentrations and radiocarbon (!''C) measurements
from a wintertime 1984-1985 study of Albuquerque suggested that, during this lime of
year, residential wood combustion (KWC) and motor vehicle emissions were the
primary sources of ground-level CO concentrations [Einfeld et al. (1988), Klouda ct al.
(1986) and (1988)].
The major objective of this study was to reevaluate these source contributions
in light of the more recent implementation of no-burn days based on the
meteorological forecast 24 hours in advance. Whole air samples were collected during
the Winter of 1989-1990 in Albuquerque, NM, for CO concentration and l4C
measurements. Since resources for this study were limited, a 23-factoriaI design with
limited replication was used to obtain optimal source information given a constraint of
10 ambient samples. The three-factor two-level sampling design included the
following: 1) sampling location; residential w traffic sites, 2) timc-of-day; 0630 to
1430 vs 1630 to 0030, and 3) forecasted meteorology; dynamic w stagnant air mass,
to effectively cover time-space. On three occasions, samples were collected for target
periods of maximum wood burning, as predicted by (he forecast meteorology that
suggested times of cold stagnant air which would likely result in temperature
inversions with little mixing. Radiocarbon results, assuming that a measured "CO
background component applies, indicated that the contribution of RWC ranged from
0% to 32% for all samples analyzed. For samples collected when conditions were most
favorable for high CO but designated as no-burn, the RWC contribution ranged from
0% to 18%. The data suggested that the no-burn strategy has been effective and that
further controls on motor vehicles may be necessary especially during unique periods,
e.g. over Christmas holiday, when the NAAQS is more likely to be exceeded.
Additionally, the relation of fossil CO and benzene was explored in light of a possible
reduction in an occupational health and safely standard from 1 ppmv to 0.1 ppmv.
Einfeld et al. (1988), Sandia Report, SAND88-0121.
Klouda et al. (1986), Radiocarbon. 28, 625.
Kloudu et al. (1988), J. Radiounal. Nucl. Chem.. 121. No. 1, 191.
849
-------
Progress toward Validating the Separation of Atmospheric Volatile
Organic Carbon from Air for 14C Measurements
George A. Klouda, George C. Rhoderick, and Robert I.. Sams
National Institute of Standards anil Technology
Ciaithcrsburg, MD 20899
Charles W. Lewis and Robert K. Stevens
U.S. EPA
Research Triangle Park, NC 27711
Rei A. Rusmussen
Oregon Graduate Institute
Ueaverton, Oregon 97006
It is well known that atmospheric volatile organic compounds (VOCs) from
fossil and biomass sources contribute to the production of ozone (Os) during summer
months via photochemical pathways. The degree to which each source pailicipates in
the chemical process is important to help design effective strategies to control O,
levels in urban atmospheres. An accurate measure of source contributions can be
obtained from radiocarbon (14C) measurements made directly on the VOC fraction.
With the sensitivity of accelerator mass spectrometry v'CJnC measurements now at 10
/Ag modern carbon (1 /
-------
Atmospheric Chemistry of Unsaturated Oxygenates:
Alcohols, Aldehydes, Ketones and Esters
Daniel Grosjean and Eric Grosjean
DGA, Inc.
4526 Telephone Road, Suite 205
Ventura, CA 93003
It has been known for many years that biogenic emissions include unsaturated
oxygenates such as alcohols, aldehydes, ketones and esters. Yet, while the atmospheric
chemistry of other important biogenic hydrocarbons (isoprene and terpencs) has
received much attention, little is known regarding the atmospheric persistence and fate
of unsaturated oxygenates. As olefins, unsaturated oxygenates are expected to be
oxidized in the atmosphere in pathways initiated by their reactions with ozone and
with the hydroxy! radical. These reactions produce carbonyls, carboxylic acids, and, in
the presence of oxides of nitrogen, peroxyacyl nitrates. Thus, information on the
atmospheric chemistry of unsaturated oxygenates is important in the context of
assessing the role and impact of biogenic hydrocarbon emissions.
We have measured ozone reaction rate constants for a number of unsaturated
alcohols, esters and carbonyls. Using these rate constants together with
structure-reactivity relationships, rate constants have been estimated for the reaction of
the hydroxyl radical with the unsaturated biogenic oxygenates of interest. From these
kinetic data, estimates could be made of the atmospheric lifetimes for a number of
unsaturated alcohols, esters and carbonyls. Wc have also investigated, in laboratory
experiments carried out under conditions that are relevant to the atmosphere, the
oxidation of the unsaturated alcohols cis-3-hexen-l-ol, 3-buten-l-oI, and ally! alcohol.
Two types of experiments have been performed, one involving sunlight irradiations of
unsaturated alcohol-NO mixtures and the other involving the reaction of ozone with
the unsaluialed alcohol in the dark. Carbonyl and peroxyacyl nitrate products of the
alcohol-NO reaction in sunlight have been identified and their concentrations
measured. Peroxypropionyl nitrate (1TN, CH3CH2C(O)00N02) was a major product of
cis-3-hexen-l-ol and accounted for 14-20% of the initial NO. Atmospheric persistence
of unsaturated alcohols and implications for the formation of propanal and I'PN from
biogenic emissions of cis-3-hexen-l-ol will be discussed.
851
-------
Atmospheric Chemistry and Fate of C2-C5 Peroxyacyl Nitrates
Daniel Grosjean, Eric Grosjean, and Edwin L Williams III
DGA, Inc.
4526 Telephone Road, Suile 205
Ventura, CA 93003
Peroxyacyl nitrates, RC(0)00N0- (PANS), aie of major importance in
atmospheric chemistry. They have also received attention as toxic air contaminants:
the several PANs studied so far aie eye irritants, mutagenic and phylotoxie. While the
simplest compound, PAN (CI l-(.'(0)OONO,), has been studied in detail, little is known
regarding the ambient concentrations, atmospheric persistence and atmospheric fate of
higher molecular weight PANs.
In this study, we have investigated twelve saturated and unsaturated aliphatic
PANs, R = CH,(PAN),GH5,C,H: (2 isomers), C.H, (4 isomas), CH; = CH-, CH; =
QCH,)-, CH, = C(C2H,)- and CH,CH = CH-. These compounds have been
synthesized in the liquid phase, prepared in-situ by sunlight irradiation of NO-carbonyl
mixtures (e.g.. (H_, = C(C-H:i)C:(0)00N0, from NO and 2-ethvlacroIein), measured at
ppb levels by electron capture gas chromatography, and characterized using a number
of chemical and physical diagnostic tests. Thermal decomposition, a major loss process
for all PANs in the atmosphere (RC03N0. -* RC03 + NO,) has been studied at
ambient temperature and 1 aim. of air. Other removal processes studied include
reactions with OH, and, for the unsaturated PANs. reaction with ozone. These removal
processes will be discussed with respect to the persistence of PANs in the atmosphere.
852
-------
Comparison of Ambient Ratios of NMHCs and CO to NOx with
Emission Inventory Values for Atlanta
I'inio
U.S. EPA
Research Triangle Park, NC 27711
M. Somerville
METI
Research Triangle Park, NC 27709
Ratios of NMHCs and CO (o NOx obtained during the 1990 Atlanta Ozone
Precursor Study are compared to values predicted by emissions inventories. Ambient
data and emissions inventory values for the early morning rush hour are used
following methods originally adapted for the Los Angeles Air Shed by Fujita et al.
(JAW.VIA, 42, pp. 264-276, 1992.) A number of factors which could alTect the
conclusions of ambient data-emissions inventory reconciliation studies such as the
photochemical processing of emissions, transport from background areas and the
effectiveness of pollution contiol devices are discussed. Results from these analyses
are qualitatively consistent with other studies from the Los Angeles air basin and the
Lake Michigan air quality region, indicating an underprediction of these ratios by the
emissions inventories compared to ambient data.
853
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Intentionally Blank Page
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SESSION 20:
RUSSIAN AIR POLLUTION STUDIES
-------
Intentionally Blank Page
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MEASUREMENT OF TOXIC POLLUTANTS IN RUSSIA
CITIES AND THEIR EFFECT ON HUMAN HEALTH
Dr.Emma Bezuglaya
Voeikov Main Geophysical
Observatory,
Karbishsva 7, 194018
St.Petersburg, Russia
ABSTRACT
This paper includes the results of measurements of
concentration benz(a)pyrene, benzine, phenol and formaldehyde in
Russian cities for 1992. The effect of meteorological conditions is
shown. This presentation includes discussion of the effects of
annual means concentrations toxic pollutants on the number of cases
of adult population of cancer tumours cases for 47 cities of former
USSR for period of 1986-1990.
INTRODUCTION
The national network of air po'lnricn (AP; in Russia assess
concentrations of not only widespread pollutants, but also many
toxic pollutants.
To assess benz(a)pyrene (BP) concentrations, dust is collected
on aerosol filters 3 times cf day during a month and analysed.
Phenol and other pollutant concentrations are assessed by sampling
20 min. Methods to assess concentrations of pollutants are given in
Guidance (1991).
To estimate the degree of AP in a city the measured values of
pollutant concentrations are compared with air quality criteria -
maximum permissible concentrations for Russia (MFC) or WHO
standards.
RESULTS OF MEASUREMENTS
The data of the benz(a)pyrene (BP), benzine, phenol and
formaldehyde mean concentrations and number of measured stations
in Russia for 1992 are given in Table 1. The mean concentration of
BP for all cities of Russia is 3 times higher, of benzine 3.6 times
higher than WHO standards, of formaldehyde 3 times higher, of
phenol 1.1 times higher than MPC. These concentrations for 5 years
(1988-1992) are increased in many biggest cities of Russia (Fig.1)
(Annual Report, 1993).
It was important to take into consideration the effect of
meteorological conditions in spread of benz(a)pyrene. The most
unfavourable conditions for spreading pollutants are observed in
the Eastern Siberia and particulary ir. the Trans-Baikal area. In
this areas with high air pollution potential the mean
concentrations of BP are more than twice as high as in the rest of
part of Russia (Fig.2).
The formaldehyde concentrations are higher near high ways in
summer month under high solar radiation intensivity. In all biggest
cities (more 500 thousand population) the relationship between
annual mean formaldehyde concentration and latitude of place is
rather clear. Correlation factor equals 0.62.
857
-------
EFFECT OF AIR POLLUTION ON HUMAN HEAI.TH
This research has been supported by the Research Support
Scheme of the Central European University.
To study the effect of air pollution on human health, the
annual mean concentrations of different pollutants have been used
for 47 cities for the period of 1936-1990 from Annual Reports
(1987, 198?., I9R9, 1990, 1991) published by Main Geophysical
Observatory.
For statistical analysis there were chosen cities where the
data are available fcr the recent 3 years and where the regular
measurement results for each month of the year during 3 years or
more are available on benz(a)py~ene or formaldehyde or phenol
concentrations since, as is well known, it affects considerably the
morbidity with cancer diseases.
From 1932 in the USSR the complex program "ASIS-Health" 'ASIS
is automated state information system;, existed. To carry out the
work, the data of this information system kindly provided to me
Dr . Yu.A.Ahrcsimova, and from Protection of environment (1989) are
usee on the number cf cancer tumours cases (NCTC) for the above 47
ci t ies.
The data were not used for the cities located in the area os
Chernobyl A?P influence where the effect of radiation pollution can
prove to be higher than that of chemical air pollution.
An important problem in studying the dependence of human
morbidity en air pollution is establishing a complex air pollution
index (API} which would characterize the real state of pollution
by many pollutants. API has been developed by Bezuglaya and others
( 159".) . It is calculated from the mean concentration of the i-th
pollutant (x), the daily mean KPC and the class of danger o- each
pollutant.
n x
J (n} = I J. = £ i } (1)
i=l M?C
C. is coefficient allowing to reduce the degree of air pollution by
the i-th pollutant to the degree cf air pollution by sulphur
dioxide; C, is equal 1.5, 1.3. 1.0 and 0.9 fox 1, 2, 3 and 4 class
of dancer.
API sums up the above annual mean concentrations cf 5 harmful
pollutants determining the basic contribution to air pollution
level, including ben7; ( a) pvrene, formaldehyde, phenol and others.
As a result of joint statistical analysis of the data on the
N'CTC and API for 1986-1990 reliable conclusions were drawn on the
effect of air pollution cn morbidity. The factor of correlation
between these values in different years was 0.42-0.69, for the
whole period Q.60^0.07 (Table 2).
Table 2 also demonstrates that the coefficient b related with
API is stable. In all variants of calculation "b" changed within
0.11-0.13. This points to the fact that the increase of air
pollution is followed by the increase of the NCTC. The regression
equation has the following form:
» = 1.80 t 0.11 3 (2)
858
-------
The type of deper.denceis is shewn In Fig.3.
The lower limit of the number of cases of morbidity is almost
the same for each year. The minimum NCTC increases clearly with API
growth. Therefore Cur each year we selected cases related to the
lower limit (41 cases' and ftoxa these data the regression equation
was calculated. The correlation proved to be very high, r = 0.934.
In the. absence; of ether harmful effects the NCTC cases caused by
air pollution can be estimated from formula
N„., = 0.14 J (3)
From this equation one can assume that at J = 10 the rainijziunt
number of cases of diseases would equal 1.4 per 1000 men and at I
= 2C it would double.
One can assess the values of API at which one case of cancer
would appear. Tt 1s scuai 7.14. APT is a total air pollution by 5
pollutants. Therefore- or.e cane of disease is observed when MPC is
exceeded cn the average for these v pollutants by 42; only.
The conclusions were checked against independent material of
27 cities fcr 1590. The results ox checking show that the error of
diseases is 29?..
For 17 cities fcr which necessary information on API and
morbidity was available for 5 years there were calculated trends
of these values. The decrease in the NCPC was hardly observed
:0.6V. when air pollution decreased by 5%. I c is evident that the
decrease in the number of diseases as a result of reduction in air
pollution level dees r.ot occur immediately. The consequences of
high air pollution in cities would show up as the NCTC from now
over many years.
Considerable contribution to the high level of urban air
pollution is made by mean BP concentrations. For cities under study
the contribution of BP to the total API is 25-70-5. It is beleeved
that BP and other carcinogenic pollutants against the background of
the general high level of air pollution determine the number cf
cancer cases. However the probahi 3 i ty i s high of diseases under the
effect of formaldehyde, phenol and other toxic pollutants present
in the atmosphere.
Comparison of the USA technique (W.F.Hunt and others, 1985 1
for the risk assessing and actual data on the NCT cases in Russian
cities shows the good agreement. The sum of the risk estimates has
been calculated on the basis of the US risk assessment (RA) data
[E.Anderson, 1982) and air pollution concentrations for this
obtained from the real results of observations from the 47 cities
of Russia and the data on malignant rumour cases (N.) for the above
47 cities. The relationship between the mean US risk assessment
(RA) and malignant tumour cases in Russian cities is good (Fig.4).
At high pollution levels one can forecast the increase of
probability of up to 5 cases of cancer diseases per 10C0
inhabitants from 17% at API > 10 to 32% at API > 20.
CONCLUSIONS
1. The mean concentrations of toxic pollutants in Russian
cities are high and are. increased in many biggest cities for 5
-------
year. The moast unfavourable conditions for spreading pollutants
are observed in the Eastern Siberia with high air pollution
potential,
2. Conclusions have been drawn as a result of statistical
analysis of data on the number of cancer cases and AP levels for
1S86-1990 in 74 cities. The factor of correlation between APT and
morbidity is 0.60+0.07. The possibility of estimating the minimum
of cases of diseases is shown. The error of estimating the number
of cases of diseases is 29?. The contribution of BaP to the total
API is 25-70%.
REFERENCES
1. Guidance on air pollution monitoring; Gidrcmeteoizdat,
Leningrad, 1991; p 693.
2. Annual Report on the stare of air pollution of cities of Russia,
1992; E.Yu.Bezugiaya, Ed.; Main Geophysical Observatory,
St.Petersburg, 1S93; p 314.
3. Annual Report on the state of air pollution of cities and
industrial centers of the Soviet Union. 1990; E.Yu.Bezuglaya,
Ed.; Main Geophysical Observatory. Leningrad, 1991; V.l, p 374.
4. Protection of environment and raticnal use of natural resources
in the USSR; Finances and Statistics, Moscow, 1989; p 174.
5. Bezuglaya,E.Yu., Shchutskaya,A.3 . , Smirnova,I.V.; Air pollution
index and interpretation of measurements of toxic pollutant
conrcntrations;
6. Hunt.W.F., Faoro.R.B., Curran,T.C. et al; Estimated Cancer
Incidence Pates for Selected Toxic Air Pollutants Using Ambient
Air Pollution Data; US EPA, Reserch Triangle Park, Ncth
Carolina, 1935.
7. Anderson, E.; Quantitative Approaches in Use in the United
States to Assess Cancer Risk, Paper presented at the Workshop on
Quantitative Estimation of Risk to Human Health from Chemicals
in Rome, Italy, or. July 13, 1982.
860
-------
Table 1. Number of stations (N) and pollutant concentrations
(x,ug/m!) and maximum permissible concentrations (MPC) in
the Russian cities
Pollutant
N
X
Stand,
deviat.
Standard
| max
Ci ty
BP
327
0.003
0.005
0.001(WHO)
0.086
Bratsk
Benzine
54
90
95
2 5{WHO)
0.28
Podolsk
Formalde-
hyde
248
9
9.7
3(MPC)
28
Lipetsk
Phenol
221
3.3
3.2
3(MPC)
12
Usclve-
Sibirs'koye
fable 2. Results of statistical analysis of the relationship
between cancer tumour cases and API
Year
a
i a
b
i b
r
r' 1
R
19B6
1.59
1.06
0.11
0.03
C. 69
0.48
22
1987
1.47
1.17
0.13
0.03
0.58
0. 34
31
1988
1 .86
0.98
0.11
0.02
0.65
0.42
39
1989
1.93
1.25
0.11
0.04
0.42
0.18
40
1990
1 . 58
1.16
0.11
0.02
0.66
0.43
45
For the
whole period
1.80
1. il
C. 11
0.01
0.60
0.36
180
From
averages
1.67
1 .00
C . 12
0.02
0.62
0 .38
4 1
K61
-------
X
i C
, r
19U<3 IfldO
Fig.l. Annual means of phenol concentrations (x, yg/m'; in some
cities: 1 - Krasnodar, 2 - Magnitogorsk, 3 - Novokuznetsk,
4 - Tomsk
i
ton *?F
tljh HP?
Fig. 2. Mean concentrations (x * 10', \ig/cf*') of her.zapyrene in
groups of cities situated in different zones of meteo-
rological air pollution potential (APP): low APP, high A.PP
862
-------
API
I
a a
API
Fig.3. The relationship between the number of cancer tumours cases
(N) and API: a) 1990; b) from averages for 1986-1990
863
-------
The rslati onship between the mean US risk assessment (RA
and malignant tumour cases (N) 1983, 1590
8(54
-------
EXAMINATION OP ATMOSPKKRIC DIFFUSION CALCULATING SCHEMES
UNDER EXPERIMENTAL DATA
Sergey A. Groirov,
institute cf Global Climate and Ecology,
20-8 Glebovskaya St., Moscow, 107238 Russia.
Veronica A.Ginzburg.
Moscow State University,
Moscow, Kussia
ABSTRACT
Application of atmospheric diffusion models for calculation a
pollution level of air is immediately related to scttisf yiny oi re
coived aata. Evaluation of oot.eiJ.ned results by field and regular
measurements gives the possibility to postulate that relative dif-
ferences of values are decreased if averaging period grows. Kf» pro-
needed the first investigation phase of air pollution diffusion
model which are used in studies of background monitoring data analy-
sis and evaluations oi environmental pollution irora local sources.
Basic model formula realizes analytical equation in Gaussian ap-
proach with dispersion parameters by Brigg's approximation. Calcu-
lating scheme and program were modified according to experiment- con-
ditions. The wind-tunnel experimental measurements of diffusion were
used for study in the case of floor roughness surface. The compari-
son shows a good correspondence oi results.
INTRODUCTION
A great part of modern investigations of the dangerous pollutant
influence are devoted to people's health and natural ecosystem
stability. However, the measuring the concentration in real
atmosphere is a very laborious and time-consuming task. One of the
perspective ways of the estimation and prediction of pollution level
is creation and using of dispersion models simulating the processes
in the boundary atmospheric layer (BI'Lj .
Unfortunately, theoretic formulas of atmospheric diffusion
nodels and methods of paraznetrization cannot give a fully adequate
sicture of real situation. The most of them requires considerable
idaptation before being applied to regulatory practice. One of the
/ays of model examination is a comparison of the model results and
.he data of field or laboratory experiments.
Generally, there are two model types used in practice for
:alcular.ion of concentration fields from different sources. One of
hem is based on analytical solution of semi-emp.- rical turbulence
iffusion equations and uses different application forms of
.iffusion coefficients and mean velocity. Another one is based on
he statistic approaches. In this case the estimated pollutant
oncentration from sources depends on the application of dispersion
arameters for Gaussian plume models.
The number of such Caussian type models wore presented in
iterature [1,2,3]. Now such model schemes are adopted to regular
3ing in ecological investigation with the aim of determination oi
mg-term industry-made impact on environment in Russia.
The purpose of our study was to examine of atmospheric diffusion
il dilating schemes based on the Gaussian model according to
cperimental data. We were interested to know how this calculating
-------
scheme could simulate the concentration tram sources of different
height and at what distance we could receive closer results by data
o£ natural experiment.
STUOT D3TAIL
Experimental Data
The results of the experiment made in the Environmental Sciences
Research Laboratory, BPA were used as a data on natural experiment.
This research was conducted in meteorological wind tunnel of EPR's
Fluid Modeling Facility. In this tunnel a near-equilibrium boundary
layer with nominal depth of 1 m was produced. It allowed to provide
an equivalence of full-scale boundary layer with a scale ratio of
1250:1. Specific characteristics and results of this experiment were
described in [4,5] .
The certain stack heights and concentration profiles were chosen
to examine diffusion model: for stack height of 80 itot the
longitudinal profile of ground level concentration (GLC) and lateral
profiles of GLC and on height of 120 nun at distances of 625, 1250
and 2500 mm from the source and vertical profiles at the same
distances; for stack height of 160 mm the same are but at the
different distances from the source (825, 1650 and 3300 mm) and, in
addition, the longitudinal profile at the height of 120 mn.
The results received from experimental data were converted
according to real atmosphere using the scale ratio of bpl (1:1250).
Model detail
We investigated the Gaussian diffusion model which are widely
applied in practice. It is the most simple scheme for calculation of
the plume diffusion from the stack and it needs the small set of in-
put data. At the same time it allows to use different conditions of
atmospheric stability by set of dispersion parameters according to
Pasguill classes and frequency function of wind velocity and direc-
tion. Gaussian models are based on the assumption of normal distri-
bution of the pollutants across the plume. The main equation of used
model for the elevated point source is following:
C(w,-sn,
where C - estimated concentration; Q - source flow rate; U -
mean wind velocity; o , o - the dispersion parameters in horizontal
ar.d vertical directions; H is the stack height.
This equation was written under the condition that plume axis i:
directed along the wind velocity vector. We used foxinulas lor dis-
persion parameters recommended by [1] in this model (Table.1):
ax bx
a = - ;
-------
of 200 m are presented in Table 1.
Good results of comparison of GLC axe received tor longitudinal
profile estimated under Pasquill stability category D. However, if
we compare the convergence of calculated and measured results for
longitudinal profile of glc and at the height of ISO m one of the
last case is better.
Fig. 1 shows plots of measured and estimated concentrations tor
C and D stability types for chosen lateral profiles. Estimated lat-
eral profiles for both stability categories quite exactly draw the
shape of measured concentration plots but their numerical values are
different. The best accordance of estimated and measured data arc
observed for lateral concentration profile at the distance of 4125.0
m from the source and at the height of 150 m under stability class
D. Generally, measured values agree with estimated on the surface
much worth than at heights for lateral profiles. The best results
for higher profiles are received for neutral stratification of flow
(class DS.
For vertical profiles convergence of results is better at
heights more then 140-160 m under stability class D for any distance
from the source and the best is at the distance more than 2000 m. in
our study we received the best correspondence between measurement
and estimated concentrations at height. This results are differed
from those presented in [1]. As the results of our study we also de-
tected that investigated model simulated diffusion at the middle ana
far distances better than near the source (Fig.2).
CONCLUSIONS
Investigation of used Gaussian diffusion model has been made tor
definition of its widely application in practice. The results of
this study showed that this model described better the diffusion at
height and at middle and far distances from source. Of course, the
physical experiment which was made in artificial wind tunnel
couldn't represent ail diversity of atmospheric conditions. Ill addi-
tion, any model is only idealization of reality and it is necessary
to verify model parameters according to local conditions of applica-
tions .
One has to use climatic frequency functions of wind velocity and
atmospheric stability for model application in ecological studying
practice. On this case errors of measured wind values, climatic av
erages and uncompleted definition of the source feature contribute
to the final common error values of concentration. From this point
of view it is necessary to make an estimation of model sensitivity
to different types of errors.
Presented study shows the influence of calculating scheme of
diffusion to the final results only. We plane to make a more complex
evaluation of different error influence on results which could be
used in ecological expertize.
3EFERHNCES
1. Hanna,S.R. Review of atmospheric diffusion models for regulatory
applications, WMO Tech.Rep. No. 501, 1983; 72 pp.
I. Niemeier,L.Kr. A practical guide for atmospheric pollution
calculation, WMO Tech.Rep. No. 610, 1987; 32 pp.
!. Byzova,N.L., Garger,E.K., Ivanov,V.N.; Experimental atmospheric
diffusion studies and pollution dispersion calculations;
Hydrometeoizdat: Leningrad, 1931; 278 pp.
Thompson,R.S., Snyder,w.H.; Dispersion from a source upwind of a
three-dimensional hill of moderate elope.; Appendix_C: Data
867
-------
report EPA Complex Terrain Model Development Fourth Milestone
Report; K PA-6 00 - 3 - 84 -1 "1 0; U.S. Environment a J protect ion Agency:
Scsearch Triangle Park, 1984; 46 pp.
h. i.awson, K . ti. , Snyder, w.H., Thompson, K . S . ftrmnn . Knvi .con 1989 2.,
321-331.
Table i. The ser. of values for equation (2) according to
Paoguili'R stability class.
Paaquiil'o stability class C D
0 . 08
0. 06
0 . 0001
0.0015
Table 2. The statistics ot relative deviations for different
proiiies under the Pasquill's stability classes
C (upper value) and D.
Profiler. Average Median St. dev. Extremes
Longitudina
1,
GLC
3
. 20
0
.48
42 ,
.55
103
.05;
161
.£6
0
. 61
0.
.89
0,
.13
0
.67;
1
.25
Longitudinal,
0
. 62
0
. 64
0
.05
0
.53;
0
. 6 7
z-150
m
0
. 24
0
. 21
0,
. 25
-0
. LO;
0
.65
Ij3 t e r a 1, G
I..C
-0
. 58
_ 2
. 96
49
. 3 6
-82
.45;
314
.85
x=2ono
m
0.
. 89
0
.83
0.
. B3
-0
. 59;
6
.15
Lateral,
150
in
-0.
. 05
0
.45
1,
.53
-8,
.10;
0
.68
x-- 2 0 0 0
in
-0 .
.45
0 .
. 0002
L ,
.35
-7 ,
.12;
0,
. 27
Lateral, C-
LC
- 2.
. 58
0
. 10
9
. 39
-60
. 34 ;
0
. 57
X=4000
m
0 .
. 05
0 .
.68
2 ,
, 11
-12
• 91 ;
0 ,
.79
Lateral, z=
15 C
m
-0 .
.60
0
.26
2 .
.75
16
.29;
0
.60
x=4000
m
-1.
24
-0.
.31
2
.93
- 17,
. 94;
0.
.06
Vertical,
1.
, 11
-0
.23
48 ,
,31
-221
.06;
253
.71
X---1000
n
-0.
.49
0.
.76
0,
. 53
- 0 ,
.54;
1.
. 09
verti cal,
0 .
. 07
0.
. 31
0
.67
. 09;
0,
,70
x=2000
m
0 .
.32
0 .
,41
0 .
. 44
-0
.41 ;
0 .
,90
vertical,
0 .
.49
0 .
. 52
0.
. 12
0
.09;
0 .
.64
X 4000
m
0.
.18
0 ,
, 18
0 .
,36
-0,
.40;
0.
,77
a
b
0.11
0 . 08
0.0001
0.000 2
868
-------
Lataral profilaa of aatiftatad and .."Lataral prof of mmtimmtmd and nRiiurad
¦aiurtd concantrat ion at diat. 2062.6m /*,. qXc at diat. 2062.5 m
(a
~ »CHI witl^ C
-*¦ ¦cHi witH o ^
¦* CHJ m«jl*L|r»d 9*i5r
/;
/. j V:
' V
*
; *
•an ¦
L ;
1 *
. - Uu_!
-309 see -lee e 10
Y, .m
J. l_; a—I jU i J
200 360
- aCHI with: C
aCHX witH O
: I
''"CHl"maai«Drad
j 1
•: 1
e.iin /
h /
i 1 / .
Vxn
Ml
Ida 200 360
-.300 -200 -1
a
Lataral prcf of aatimatad and maaaurad : •> aCHI witH
— aCHI with
»CHl witt
1 maa'aC
* CHI maasC
0. 113
e. oe
a. 06
609 -460 -200 9 206 400 600
-280 0 209 490 60
600 -488
:entrations fo^C ^solid^ine) a"d ineasurecl (star line)
ses for: (a) x^2000 m and 2=lso m- lonn1"5' ®tability
00 m and z=0;
-------
6',
T
UERTCD. r«lCFi -
yERTCC,.r.*iC& 3
-lie
Rellftic® efauiatlon of,medium di«t»nc«
• ¦tifn«?«a concBntrition 6g maa»urid
r«lOH -
... - f: VERTMC. r«lC
R«JUitiu«, d«ui«tion jxT fmr dJL«t*rc«.
tsYTmAii«d conciniratlon du ffli«turid
UERTFD.r«lCH :
¦f YERTF3.r«ICW -
0.78
1,26 f"
e.25
Fig. 2. vertical, profiles ot relative deviations of estimated
and measured values for C (dashed line) and D (solid line) stability
classes for: x=1000 m (a), x-2000 m ) and X--4000 m (c) .
870
-------
Background Pollution of the Atmosphere:
The Multi-Year Observation in Russia
/•'. Rovinsky
Institute of Global Climate and Ecology
The observations on the integrated background monitoring program at a
network of stations in biosphere reserves embracing a considerable part of the
Eurasian continent began late in the seventies in the former USSR. The atmospheric
part of the programme envisages daily evaluation of sulfur and nitrogen compounds,
ozone, heavy metals (Pb, Cd, Hg, Cu, Zn, etc.), organochloride and pulyatomalic
compounds. The same compositions of the components are evaluated in precipitation
samples.
The spatial distribution of background concentrations for the most of pollutants
is irregular: a decrease could be observed eastwards and northwards, and the
concentrations are significantly lower in the mountain areas also. This regularity is
mostly distinct for pollutants of fuel-power cycle - sulfur and nitrogen dioxides,
benzpyrene, Pb; as for DDT and HCCH the regularity is weaker.
The time-related daily and seasonal variations are present. These variations are
connected both with power source volumes and atmospheric processes.
Multi-year trends demonstrate that during the last decade the mean annual
sulfur dioxide, benzpyrene and Pb concentrations are 2-4 times lower in the western
and central parts of (he European territory of Russia and they practically do not
change over the southern Russia and Siberia, and the DDT concentrations
monotonously decrease with time.
The assessment of the anthropogenic, heavy metals contribution (Pb, Cd, As,
Cu, V) in background pollution of the atmosphere was obtained with the help of
the geochemical relations methods. This value changes from 20-50% lor the
continental regions up to 70-98% in the western part of the former USSR (more
urbanized).
The mulu'-year statistical data on background pollution of the precipitation
and their acidity demonstrate that noted irregularities for the atmosphere in the whole
are characteristic for the precipitation, as well.
As it is shown bv the multi-year observation data, the background pollution of
the atmosphere endure the anthropogenic influence over large-scale territories.
871
-------
Methods of Studying Sources in the Boundary
Atmospheric Layer of the Background Areas
V. Egorov
Institute of Global Climate and Ecology
The data on major sources required for assessment and prediction of ozone
variation in the boundary atmospheric layer and their effects on environmental
objects. The most important sources of ozone input in the lower atmospheric layers arc
photochemical reactions and transport from upper atmospheric layers, advection of
ozone and its precursors.
The method of the simultaneous measurements of ozone in the chamber
volume filling by ambient air and in the outdoor atmosphere was applied to study the
effect of photochemical ozone production in the atmosphere of the background areas.
The material used as chamber shell was inert with respect to heterogeneous ozone sink
and transparent for solar radiation.
The results of carried-out observations indicate of ozone concentration
exceeding in chamber from 10 to 100 percent in the Berezinsky reserve area (Belarus)
in the daytime (July) caused by its photochemical production in comparison with
ozone content level in the outdoor air.
Used technique allows to estimate the upper boundary of ozone content in
the air is caused its photochemical sources in the observation area.
The effect of air transport and possible photochemical ozone production on its
content level in boundary atmospheric layer was investigated with help of ozone
gradient measurements method and meteorological parameters (air temperature, speed
and direction of wind). For this purpose was using captive balloon (v-800 m5)with the
hasket containing measuring instruments.
The results of the measurements carried out in the background area of
Kurakaya district, their comparison with existing data in world literature on type of
vertical ozone distribution in the lower atmospheric layers indicate of dominant effect
of ozone convcctive input in the near surface layer for the upper atmospheric layers
during observation period (June - August).
K72
-------
APPLICABILITY OF TRAJECTORY ANALYSIS FOR AIR BACKGROUND
MONITORING NETWORK OPTIMIZATION
Sergey G.Paramonov
institute of Global Climate and Ecology,
20b Glebovskaya St., 107258 Moscow, Russia
ABSTRACT
At present time four air background, monitoring stations working
over European part of Russia. A number of pollutants' concentrations
in the surface layer of air are measured by these stations
constantly. The level of observed concentrations depends on the
lifetime of substances in the atmosphere and the anthropogenic
emission sources density over the path "source-receptor". The areas
whose emission influences to the pollutants' concentrations in the
fixed receptor site were estimated with help of a back-trajectory
model. The model permits us to calculate five-day back trajectories
according to ageostrophical relations between fields of wind and
pressure.
The trajectory calculations for Russian background monitoring
stations started in July 1989 and since that time are executed
everyday. Database of more then 6000 trajectories are collected. All
trajectories were classified and statistics of long-range transport
were estimated. On the basis of this data, the areas of polluted air
parcel's path were determined for each monitoring station for the
periods one, three and five days. The areas have a complex shape and
are extended backward along the prevailing air transport direction.
Additionally there are territories where the areas around different
stations intersect each other. In the same time there are a vast
territories, pollution transport from which isn't under observation
of the existing monitoring network; the considerable parts of the
North-Bast European Russia, Kola peninsula, West Ural are among
them. The named regions need additional air pollution monitoring
station organized.
INTRODUCTION
The estimation of territory's size which could be representative
for air pollution observations in one local site is one of the
speculative questions in air background monitoring. This territory
will be obviously different in every determine case due to
peculiarities of pollutant's emission field, surface roughness,
neteorological conditions. It may be suggested that the territory
trill vary for different pollutants characterized by their lifetime
In the atmosphere. And the shorter lifetime of specific pollutant,
;he more monitoring station are need for air pollution observation
iver the test region. The task of territory's size determination
ibserved by one stationary air background monitoring station (BMS)
lay be solved on the base of air parcels trajectories' analysis.
The method of trajectory analysis is well-studied and widespread
or investigation of the pollution transport to or from fixed site,
ut only the few works consider a vast data bases (about 102-103
rajectories) , for exan^xle the study by J.M.Miller devoting to
rctic trajectories' climatology (Miller, 1981). In Europe and
ussia there almost have no investigations of similar nature with
ong-term trajectory data sets. The appreciable trajectory model was
reated in institute of Global Climate and Ecology by Dr. Gromov
873
-------
(Paramonov, Gromov, 1992S . The modal permit to calculate back
trajectories oi axt parcels two times a day from or to any place in
tin..' Northern Hemisphere. The input data are taken from Moscow
Meteorological Center undded fields lor standard pleasure levels.
Trajectories are calculated, tor not more then live-day period,
considering that the longer its duration, the less trajectory
accuracy.
Permanent calculations of five-day back trajectories started for
every former USSR air background monitoring station ir. July 1989.
The period oi study in this work was taken from the beginning of Uio
calculations up to September 1992. The total quantity of
trajectories used in the work adds up to 0200, 61% of which talis
within an warm season. The sites of EMS location are presented in
Fig.1. For statistical procedure a year was divided into two seasons
- cold (October-March) and warm (Apri1-September) .
TRAJECTORY ANALYSIS
Climatology of Back Trajectories.
Every trajectory was assigned to a category according to the
direction of air flow. The horizon was divided into eight 4h-degree
sectors by standard meteorological manner. The ciassit'icative
criteria for the curved trajectories, crossing the sectors'
borderline vac the trajectory presence in the definite sector more
then, half of an ait parcel's transporting time. The percentage of.
trajectories' directions are shown in Table .1. The North west and
West trajectories' directions prevail tor all BMS in both warm and
cold seasons . The total average frequency of these directions rans
to f>0% in warm and fc
-------
observed air pollution levels, contour lines were drawn, which
outlined the areas from whom air parcel may reach the BMS for one,
three and five days. Generalized outlines around all air monitoring
stations situated over European Russia are represented in Fig.i for
warm and cold seasons. As may be seen from this figure the results
of the observations for the concentrations of the pollutants with a
lifetime more then three days are subjected to emission from almost
all Europe: from France to the Ural mountains. The seasonal
variations mainly spread to marine territories where there are no
emission sources. As to pollutants with life-time of less then one
day BMS are subjected to emission from Baltic countries, Ukraine,
Kazakhstan and Central part of European Russia in the warm season.
In the cold season one need add influence of the emission from
Central Europe and Scandinavian countries. During the year emission
of pollutants with short life-time from extensive area of European
Russia from the left bank of Volga to the Western Urals isn't under
observation by existing air background monitoring stations.
The outlines around separate BMS may vary from year to year.
Sometimes yearly variation of areas within the outlines may exceed
30% (Fig.2, 1989 and 1990). As it is seen from Fig.2, variation
mainly takes place in Eastern parts of contours, information about
air pollution from where is interesting for Russia. This region of
variability is common to all considered BMS.
Network optimization
The territories under observation by separate background
monitoring stations intersect each other and the longer the life-
time of the pollutant, the larger an area of intersection. Thus the
area of intersection of at least a couple of BMB inspected territory
up to 85-95% for the pollutants with life-time from three to five
days, in this case one or two BMS will be enough to monitor the same
area which is now under observation by four stations for proposes of
long-range pollution transport monitoring. So Oka-Terrace and
Astrakhan may be suggested as such stations. As may be seen if one
compares Fig.1 and Fig.3, the outlines around four air monitoring
stations and around Oka-Terrace BMS are closely allied. The
difference takes place only in South part of the one-day contour. If
this contour is added to Astrakhan's one the total outline will be
similar to the outline surrounding all the four Russian BMS. Taking
into account typical distances from BMS to the one-five-day area's
boundaries in every sector one may choose a site to put an
additional monitoring station to inspect the North-East part of
European Russia. The best place for additional BMS may be situated
in triangle between cities Syktyvkar, Perm and Vyatka.
CONCLUSIONS
First results in trajectory climatology over European Russia
*ere worked out. This investigation is proceeding now and the new
-.rajectory data sets are added to existing ones. The applicability
)f using trajectory analysis for background monitoring network
jptimization has been demonstrated.
LEFERKNCES
. Miller, J.M. Atmnf;, Rnvj rnn . 1981 OS, 1401-1405 .
Paramonov, S.; Gromov S. vpnt-nik NfAgkrivriky-igri rini vprait-pl-a
¦Sg.r.geography 1992 £, 3 11. (in Russian)
875
-------
Table 1. The percentage of directions of 5-day back
trajectories from Russian air monitoring
stations.
Warn season Cold season
Year N
NF.
E
SE
s;v w
NW
Year
N
;cf
F
SF
5
SW
W
NW
Cer.
trai-?
orest i
BMS
89
g
1
Q
15
3
10 31
24
69-90
i"
-
1
0
2
3
32
33
SO
21
12
n
5/
5
5 24
21
90-91
11
3
2
3
9
11
29
32
Si
17
0
0
13
19
10 27
20
91-92
11
c
0
3
5
1C
26
40
92.
13
4
5
O
O
4
15 29
22
Oka
-Terrace BMS
89
J o
d
.*•
24
ti
^ o;
.j w..
39-90
-
1
'j
0
6
29
45
90
1c
11
6
J
G
£ 24
90-91
^ w
3
3
5
~
11
23
35
91
i. V
2
4
15
c
14 SC-
93
91-92
14
3
0
9
P
9
21
39
¦i. 0
c
_ 4.
C
ll 20
ul ~ :¦
Dr.e?. ?.
M3
Dl
'
J w
\ 0
19
r.
U 1?
22
90 91
1
'•N
-7
; ic
d
1 3
30
92
:.3
c
c
.-C
A 5 *.;
25
raKfcan
91-92
SMS
4
£
11
11
42
>~;C
12
12
ic
- r
2 13
2 b
89-90
B
0
r
1
4
33
S3
90
3
13
7
.
4 IS
36
90-91
11
6
5
4
c
9
29
32
91
24
fi
29
4.
2
3 c-
26
91 92
19
f
0
6
4
6
15
35
92
26
_ iC
¦ r
11
4
3 3
21
Tacle 2. Averaged in 45° soccers trajectories' sneer! <:03km/cay;.
'hssji season
Cold season
Oay
s \"
XF
E
53
£
sw
W W
ME
F,
3t
S
3W
w
XV
Oen^ral
-sorest El»
2
¦*
0 'i
0.2
0. 3
0
0
0. 7
0.5
0.9 0. 3
i.l
0. 5
0.4
0. 2
0.6
0. 6
1. 2
1.2
.-1
u
... *
0 3
0. 3
A
«_/
c.
0. 4
0. 4
0.9 0.9
0. 9
0. 3
0. 3
3 3
0.5
0. 0
•j r
1.1
j. 5
0. 2
0.2
0
3
0.3
0.3
0.6 0.9
0. 5
0. i
0. 2
0! 4
r
0. 5
2
> 1.:
OXa-Ter
~*ce
3MS
j.
0. 9
0. 3
0.3
0. 3
0. 6
0. ¦ 0."
* f*.
0 5
0. 4
0.2
0."
n 1
1 r.
i. • .
3
0. 5
0. 2
0.3
0
4
¦r "
•V - ^
C. 4
0. 5 0.5
s
6's
0.3
0.4
0. 3
H A
i . V
1.:
D
C. 4
0 3
0. 4
"J
3
C. 2
0 3
0.5 0.3
0.5
0. 3
0. 3
0.3
0. 3
Q. 4
0.-7
>1.;
Worcnei
3"S
1
o.e
0.3
0.7
"T
0. c
0 <=
r n 0
0. R
0. 3
0. s
0. f,
0. 7
C:
1.
3
^. 0
0.2
r.
C. "
0.7
0. 7 0.3
0. 7
0. 3
4
0. 3
0.1
5
0.5
0.2
0.2
c
3
0.2
0. 5
0.5 0.8
C. 6
0.2
0. 3
0. 3
0.2
0. 4
0. 6
>1.
Astrakhan BMS
1
0. e.
0. 4
0.5
r
0
0. 0
3. 2
0.0 0.6
C. 6
0.3
0. 4
0. 3
0. 3
0.3
1.1
1.
3
0.4
0. 3
0. 4
c
4
0.2
0.2
0. 3 0.5
o.e
0. 2
0.3
0.2
0. 2
0. 2
0.3
1.
5
. 4
1
0. 3
c
2
>./.
0. 1
0. 3 0. n
C.f
0. 3
0. 2
0. 1
w . i'.
0.5
H76
-------
Wsrm season XW
#|||®«ii^
Co'o season
\s ^ :v^v^:v^N
Imm^^^W^Oka-Teiracs BMS
N^v<5^^®(SSSs®i«ig^* Wororicz rifO '/.'A
N. i'/l -.
* Att rakhcr. BMSSK-:
Figure 1. Areas controlled by Russian background monitoring stations 'or
pollutants with different lifetime.
87?
-------
Warm season
1S92
1991 n
1990
1989
Figure 2. Year variations of the outer boundaries of five-day back trojecior :s
from Oka-Terrace BMS in the warn season from 19S9 to 1991.
Warm
''/wmfr
Poliu
>5 days
3-5 days
1-3 davs
:i da}
Figure 3. Areas controlled by Oka-Terr
different lifetime.
ice BMS for the pollnin::!? -.vitii
878
-------
LONG-RANGE MODEL FOR ATMOSPHERIC POLLUTION ANALYSIS
OF BACKGROUND TERRITORIES
Sergey A.Grontov,
Institute of Global Climate and Ecology,
2 0-B Glebovskaya St., Moscow, 107258 Russia.
ABSTRACT
Goals of GEMS station's measurement data analysis appear to
evaluate inputs of regional sources into long-term background
atmospheric pollution level and to investigate its seasonal or
multi-year changes. Lagrangian model is supposed to study
atmospheric pollutant transport. It is based on 5-days backward
trajectories calculated from ageostrophical wand-pressure relations
using meteorological data of Moscow World Meteorological Center. The
two-layer barotropic model of BPL included to estimate such
parameters as transporting averaged wind, turbulence coefficient and
exchange with upper layers. Pollutant advection is simulated as
moving of separate "puffs" along trajectory. Lateral diffusion is
applied as a Gaussian approach. The vertical diffusion equation is
solved numerically taking into account the BPL's results and dry
deposition which depends on seasonal features. Time-depending
decrease of concentrations by first order chemical reactions ie used
when transformation of pollutants exists. Wet deposition is
simulated by the same manner when cloudiness or precipitation takes
place. The results are concentrations and depositions in each point
for a chosen time interval. The model had been tested on analytical
evaluations of long-range environmental background concentration of
sulphur dioxide over former USSR' European territory.
INTRODUCTION
Mathematical modelling of air pollution transport is one of the
most perspective methods in the field of geographical and
geophysical investigations in ecology. It allows to create a basis
for forecasting in the natural environmental pollution and for
analysis of influence of accepting economic decisions.
The task of long-range transport modelling is to determine a
changes of pollutant concentrations and output flux intensity from
atmosphere under the influence of emission, diffusion,
transformation, deposition and washout.
Generally, regional-continental air pollution models must be
comprehensive the number of requirements without dependance on model
construction:
1. to accept a lot of emitting sources;
2. to follow a pollutant moving for hundreds or thousands
lilometers while taking into account a temporal atmospheric flow
nstability;
3. to use spatial and time-depending averaging manners of
leasurement and emission data;
4. to include a processes of chemical transformation and
emoving of pollutants from the atmosphere.
Any different types, forms and variants appear inside common
odel structure realizing the modeler' theoretical approaches and
ompramise decisions in satisfaction of requirements on accuracy,
879
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fullness, spatial accuracy, available, input information and computer
calculation effectiveness.
The operational models for estimating of transboundary pollution
flux had been constructed in both Meteorological Synthetic Centres
or EME? [1,2]. Another method of mathematical solution was
demonstrated by Praiun arid Cristensen 131. A statistical approach to
long term modelling was used by A.Venkatram f41 .
Our way of model creation is determined by practical goals of
its applications: to use model in regional - scale analyzing and
forecasting ol atmospheric pollution, to evaluate download pollutant
flows, to investigate a possible "source-receptor" relationships and
to reach calculating efficiency.
MDD2L DETAIL
The physical approximation principles of the suggested model are
the following:
1. Trace matter moves in changing wind field which could be
estimated from data on geopotential analysis. The transport paths
can be determined according to air parcel trajectories within lower
troposphere.
2. Source's plume is approximated by set of moving independent
portions of emission ("puff") which are injected at one moment. The
cloud amount is equal t.o emitted mass from continuous source for
limited time interval.
3.The influences of deposition, transformation and washout are
determined as a "living-time" functions and described by set of
parameters depended on meteorological an geographical conditions.
4. The pollutant concentration and deposition on the earth
surface are calculated for receptor point from which a backward
trajectory have been restored.
5. The value ot concentration is estimated as a sum of ones
produced by trajectory's crossing area sources lor orxe trajectory
time period.
The suggested model is classified as Lagrangian receptor
oriented. This approach allows to divi'de advect.ion and diffusion
processes during t.he solving of atmospheric substance balance
equation. General suppose of this way is: a smaller diffusion
processes place on large scale transport of pollutant masses ny
atmospheric flows.
The realization of the above principles went along the way oi
creating the block aggregated software package. The later gives a
possibility to write programs of different parts step-by-step or to
improve it without, touching others.
Independent vertical moving velocity of trace gases and aerosols
can be neglected for long range transport movements. The
differential equation oi local concentration change is solved
according to coordinate system restored in centre of laterally
moving puffs from each source fixed on trajectory and applying to
diffusion, source intensity {Q> and sinks due to washout (W), dry
deposition and chemical transformation (R) processes:
Al two dimensional Lanlacian, jCt- and - lateral and vertical
i.urbulenL diffusion coefficients.
The equation solution is found under the suppose that local
8S0
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concentration change is the result of separate influences:
C(x.^ i t) -- ZL On Pt (x,y. i,tj P. {*,?»)£.(*») >1* (U) (2) ,
P - functions of spreading (1,2) and removing (x,w); - the time
of puff moving from source N to receptor point along the trajectory.
The basis of puff travel determination is submodel of 5 days
backward trajectory calculation according to ageostrophical
relations of wind and pressure fields [5]. Estimations of trajectory
point coordinates are proceeded with 1 hour step using real
aerologies] and meteorological data analyzed and received from
Moscow world Meteorological Center. The calculating algorithm allows
to correct wind fields between terms of analyzed data reception.
The two-layer barotropic model of boundary planetary layer
(BPL)[6] is included as counting block. The BPL parameters are
determined by synoptic processes and are calculated from analyzed
meteorological data. Such parameters as averaged wind at pollutant
transport layer, turbulence coefficient profile and speed of
exchange with upper troposphere layers are estimated with help of
BPL model.
The boundary conditions for solving of iaterai diffusion
equation is the pollutant absence toward the longest distances.
Under the assumptions on semi-uniform lateral turbulent diffusion
and relationship of lateral dispersion parameter ( <7 ) and Lui'bulent
diffusion coefficient the corresponded function is following:
4 * ih->exp(-&) !3!-
- R - distance from puff centre to point (x,y).
Parametrizating formula of ( C ) is used as suggested in [7]
according to measurements during the periods of long-range transport
studies. This paramelrization approach is strongly valid for flat
territory only.
Vertical diffusion equation is solved numerically by taking into
account the BPL, mode] results and following boundary conditions: dry
deposition of pollutant on the surface as a function depended on
seasonal variations and upward transboundary flow at the top. The
later is proportional to the upward wind component calculated from
BPL model. The temporal and spatial variation of diffusions! and
depositing parameters need to bo taken into account under long-term
and long-range modelling. The BPL model is used in order to include
its influence. In addition, Lhe quality evaluations of role played
by surface type, insolation, seasonal and local meteorological
conditions show: the parametrizacion of large-scale surface
differences and seasonal deposition velocity variation is necessary
in the first Is] . Using the large-scale averaged data on surface
roughness and calculated value of dynamic velocity parameter we
assumed that dry deposition velocity can be as following:
K (h) -- Vlt [X,) I t - 4-] 1 <4 >.
¦Zs equal to 1 meter where Lhe most of data was obtained, h height
jf constant vertical flow layer, x. - Karman constant. Internal year
variation is defined by set of seasonal values.
The transport layer was divided into different thickness
sublayers. Using the varying vertical step does complicate, the
•alcuiaring procedures and need more counting time. However, as
-©ported in (8J including the additional levels into lower part of
881
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BPL allows for ix decrease in pollutant mass disbalance.
The Crank -Nikolson algorithm was used tor numeric integrating ot
finite-difference equation. The time step was limited by following
condition:
&t< nu« [2 (Sz)y)C, ] (5!_
The investigation of numerical solution features under
influences of turbulent diffusion coefficient profile and dry
deposition was carried out. We found more intensive vertical
spreading than according to analytical solution [l] (Fig.i). It
seems to be more adequate because of uniform diffusion condition is
rarer. The including of dry deposition leads to closer results. The
moving toward uniform, distribution appears to accompany movement
away from the source.
The exponential decrease of concentrations by first order
chemical reactions is used when transformation of nonconservativo
pollutants is estimated. We had tried to include the processes of
wet deposition by rainfall. It is simulated by the same manner when
cloudiness or precipitation takes place at the transport layer if it
is defined from meteorological analysis. The seasonal changes of
emission was taken into account.
The results of calculations are vertical profiles of pollutant-
concentrations, wet and dry deposition sums in the receptor point
during fixed time period:
fa H
= {{ - ey{-A«Ai)]Jc/AjAyj)«x (6>
o
The following order of calculations established for each
receptor point during single time interval of trajectory analysis
(for region the procedure is repeated for each chosen point during
same time interval):
1. The b-dayc backward trajectory line is restored. The
turbulent diffusion coefficient, BPL height and related parameters
is determined in trajectory points;
2. The set of emission sources is found by searches after each
time travel period (for example, after 3 hours) in vicinity of
trajectory points;
3. The heavy cloudiness or rainfall existing is analyzed along
the trajectory;
4. The values of lateral and vertical diffusion, chemical
transformation (if needed) and wet deposition are calculated;
5. The concentration and deposition are counted for receptor
point as a sum of particular values from each source.
Averaging of calculated values is produced after accumulation of
data for a longer time period.
The model will be used for analytical evaluations of long-range
environmental background pollution over former USSR European
territory. We was tested its applicability on calculation in
conditions of stable west flows over Europe during summer (July) and
winter (January) seasons without wet removal. Meteorological
information was obtained from base of Moscow World Meteorological
Center as regular net fields. The distribution of emission was
chosen as a square grid cell net of sulphur uptake. The modelling
results for summer situation is shown on Fig.2.
S82
-------
We compared calculated values of sulphur dioxide with measured
on background monitoring station over European part cf former USSR
in same conditions (according to trajectory analysis). This data are
in Table i. The exceeded calculated values may be explained by
enormous influence of nearest sources and, hence, not enough good
acceptance of emission data. Moreover, we cannot include here a
washout processes due to lack of data.
CONCLUSION
Presented model was created for analysis of background
atmospheric pollution according to long range transport. It includes
the main processes which exist m lower troposphere and change the
pollutant concentration, it is obvious that this model is not as
perfect as a number of others. We shall impi-ove it by using better
parametrization, good initial ana input data acceptance.
REFERENCES
1. Izrael, U.A.; Kikhailova, G.K.; Pressman, a.y. nni-i«Hy
-i Nank SgqR 1980 2iii, 848-852.
2. Kliassen, A.; Saltbones, J. fttmo.i, B.md ron1983 JLZ, 14S7
1473 .
3. Prahm, L.P.; Christensen, 0. a Rppl Met-enr 1977 X£, 896-910.
4. Venkatram, A. At-mns Rnvi rnn 1986 2H, 13 17-1324.
5. Paramonov, S.; Gromov s. Vesc.oik Mnnk n vr.Vrogn I in i vers i r pf a
6 lordanov, D.; Syrakov, D.; Djolov, G. nri'g gor-»phy« gpi«
1981 2, 10-22.
7. Heffter, J.L., Taylor, A.D., Ferber, G.J.; A Regional-
continental scale transport, diffusion and deposition model, NOAA
Tech.Memo. ERL-ARL-50; 1975, 28 pp.
8. Veltisheva, N.S. Mpfsnmlnfjiya rj i rlr-nl ng iyn 1900 2., 42 -49.
Table J. Statistical parameters of measured concentration and
calculated values for background monitoring station during west
large scale flows.
Parameters
Background station
(mkg/m1)
Berezina
Oka-Terrace
preila
Central-Forest
Average (6)
0.99
0.91
2.97
1.06
Stand, dev.
1.14
0.74
2.58
1 .09
Maximum
3 . 2
3.4
L0.9
4 . 28
Coef.variat.
114 .8
81 . 8
86 .6
103 . .1.
Calculated
b0 .
95.
10.
8 .
-------
s
Fig.l. Vertical spreading function profiles after 24 (I),
72 (II) and 120 hours (III) without dry deposition (1)
and with Vj = 1 cm/sec (2);
a) numeric solution; b)analytical solution [i~]
Leningrad
- x \ "N
mm
Av P/#Mosco^ 11
' i l \\a H \t)/
Minsk
Kharkov
Fig.2. Field of calculated sulphur dioxide concentrations over
European part of FSU due to summer west flow (measurement sites
in reserves: 1 - Berezina, 2 - Oka-Terrace, 3 - Preila, 4 - Central Forest).
8X4
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SESSION 21:
ENVIRONMEN TAL TOBACCO SMOKE
-------
Intentionally Blank Page
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REAL-TIME MONITORING OF POLYCYCLIC AROMATIC
HYDROCARBONS AND RESPIRABLE SUSPENDED PARTICLES FROM
ENVIRONMENTAL TOBACCO SMOKE IN A HOME
Wayne Ott\ Nancy K. Wilson. Neil Klepeis, and Paul Switzer
*Atrr.osphe.ric Research and Exposure Assessment Laboratory
U.S. Environmental Protection Agency
Research Triuigle Park, N.C. 27711
and Department of .Statistics
Stanford University, Stanford, CA 94305
ABSTRACT
Real-time measurement of polycydic aromatic hydrocarbons (PAH) on fine particles was
evaluated in a home with environmental tobacco smoke (TITS) as a source. The PAS lOOOi PAH
monitor (CcoChem Technologies, Inc., West Hills, CA) is based on photoelectric ionization of surface
PAH. loss of the photoelectrons. and subsequent measurement of the remaining positively changed
particles in a filter electrometer. Cigarettes were smoked in the living room of a small house, with the
time scries of PAH concentrations logged with high time resolution using a Langan DataBear LI5 data
logger. Respirable suspended particles
-------
relatively large irradiator unit and a sensitive electrometer, an instantaneous da lection of PAH is
possible. Niixsner (1986) examined the respond characteristics of ;!ie sensor to different PAH to
determine if there is a preference in charge due to the molecular structure of the PAH. Observing the
normalized concentration of charged particles at different particle sizes, he found a quantitative linear
relationship between the surface area and the photoelectric activity. The correlation coefficient
between the PAH amount (at the surface; and photoelectric activity was above r = 0.998 (n = 8
measurements! , indicating that the ser.sor signal reflects ihe amount of PAH present. He concluded
that the PAS methodology allowed for continuous, sensitive (under ng/m'} in i/rn-monitoring of four-
and-higher-ring PAH. As iong as the PAH are enriched in sub-monolaycrs, which is usually the case in
combustion situations, the method yielded quantitative information on the amount of adsorbed PAH.
Niessner and Walendzik (19X9) examined the response of the PAS monitor to cigarette smoke. They
found that the PAS results correlated we'll (r - 0.94, n = 20) with ber.zoialpyrene (BaP) concentration,
which was determined independently by in situ synchronous fhionmetry on Tl.C. plates. The absolute
lower detection limit was about 50 pg.
Wilson ei al. (in press) compared readings from the commercially available PAS lOOOi monitor
(EcoChem Technologies, Inc., West Hills, California} with 12 integrated measurements of PAH
collected by a pump-driven sampler in homes and offices with smokers. The collection device
included an annular denucler to remove vapor-phase PAH, a 2.5 um impactor to remove coarse
particles, and an XAD-2 resin cartridge to collect any PAH vaporized from the. particles on the filter
during sampling. The integrated monitors operated over an X-'n period with a sampling volume of 20
L/min. anc the filter and resin were extracted with dichloromethnne, with the extract analyzed by gas
chromatography/mass spectrometry (GC/MS). Comparison of the PAS lOOOi with the integrated
samples showed that the results were highly correlated (R: = 0.985). They found the instrument easy to
operate, nigged for use in field settings, stable, and reliable. It had a low limit of detection (around 10
ng/nv) and was highly sensitive to variations in concentrations in indoor settings. They recommended
replacement of the electrostatic precipitator (ESP) with a straight stainless steel tube, since the ESP is
not needed for indoor and ambient aerosols. The PAS lOOOi used in the present study was modified in
this manner, and a newer mode!, the PAS 1002i. is now available front the manufacturer.
Rcspirable Suspended Particle (RSP) Monitor
The. piezobalance originally was developed to monitor RSP levels in occupied buildings m
Japan, because Japanese law reqni-es measurement of RSP levels several times each day in stores,
offices, apartments, and other buildings. The theory, performance characteristics, size selectivity, and
history of its design are four.d in papers by Olin, Sent, aod Christer.son (1970). Olir. and Sem (1971),
Carpenter and Brenchley (1972), Daley (1974), Daley and Lundgren (1975). Sem. Tsurubayashi, and
Hon*.ma (1977) found, over the range of 5(1-5,500 pg/nv, that readings from 11 piezobalances were
generally within +10% and always withir, +15^. The TSI Model 8510 piezohalance is a portable
instrument designed for measuring the mass concentration of fine particles with a ?.5 (.im outpoint.
METHODOLOGY
Real-time concentration readings from the PAS '.QLHli PAH monitor with the ESP removed
were compared with successive 2-mimne average concentrations from two Mode! 8510 piezobalances
in the living room of a home. Two different types of cigarettes were smoked: a regular Marlboro
filter cigarette (Experiment A) and a University of Kentucky research cigarette reference No. 2R1
(Experiment B). The instruments were collocated on a stand 0.5 m above the floor of the living room
but were not connected to a common intake port: the intake poits weie within 0.5 in of each other. In
each experiment, two cigarettes of the same type were smoked sequentially one after another. The time
series of concentrations from the two piezobalances were recorded manually every 2 minutes from the
888
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instrument's digital display, while the concentrations from the PAH monitor were recorded
electronically at 10-secor.d intervals using a Lar.gan L15 DataBear data logger (Langan Products, Inc.,
San Francisco, California). The DataBear data logger was attached to a Macintosh lis: persona!
computer that displays the concentrations on its color monitor in real time. At the end of the
experiments, the data generated by the PAH monitor were downloaded into the Macintosh computer.
The home -- a single-story, two-bedroom, one-bathroom structure -- was 606 ft" (56.3 nr) with
a volume of 139 m\ The area of the living room was 15! ft" (-1.28 nr), and its volume was 35.7 m'.
During the experiments, the adjoining door to the kitchen was open 2"; the adjoining door to the
bedroom was open 2"; and the front door of the home, which opens into the living room, wax closed.
One window in the living room was closed and the other was opened 6" to give a higher than usual
ventilation rate for wintertime to enable the experiments to be completed within a reasonable time.
RESULTS
Comparing the two piezobalances with each other for the Marlboro cigarette in Experiment A
(Figure l, top) shows that the resulting regression line has a slope of nearly unity (RSP2/RSP1 slope =
1.12) with R2 = 0.86 [n = 49), indicating that readings from the two piezobalances are correlated with
each other and have little bias. A similar regression of the PAH readings versus one piezobalance
(Figure 1. bottom) shows a high correlation (K~ = 0.88, n = 50). but the PAH/RSP slope = 0.0138. This
result indicates that the PAH readings are correlated with the RSI' readings and that the PAH
concentrations for the Marihoro filter cigarette are about 1.38% of the R.SP concentrations.
For the Kentucky 2R1 cigarette (Figure 2, top), Experiment B also shows good agreement
between the two piezobalances (RSP2/RSP1 = 1.11) and a high correlation (R2 = 0.88: n = 38). Two
outlier data points above 700 ug/nv have been excluded from the regression, because random outliers
often occur during the "source-on" period in chamber experiments (Furraw, 1994). Occasional
deviations between the two piezobalances are not surprising for two-minute averages, since the
instruments are next to each other but are cot connected to a common sampling intake. The regression
analysis of the PAH readings versus both piezobalances (Figure 2. bottom) shows a moderate
correlation (R: = 0.66: n = 32), and the PAH/RSP slope = 0.006. Thus, for the Kentucky 2R1 research
cigarettes, the PAH readings are moderately correlated with the RSP readings, and the observed PAH
concentrations are about 0.6% of the R.SP concentrations.
The much iower value of the PAH/RSP ratio for the Kentucky 2R1 research cigarettes than for
lie Marlboro cigarettes is consistent with the relative slopes of the regression lines, which have a ratio
if 0.0138/C.006 = 2.3. Comparison of the source strengths from the two types of cigarettes indicated
hat both types emitted about the same amount of PAH, but that the R.SP emission was about 2.3 times
ugher for the research cigarette than for the Marlboro filter cigarette.
:onclusions
This study indicates that a real-time PAH monitor using a photoelectric aerosol sensor (PAS)
an generate concentration time series mat are useful for measuring effective air exchange rates and
valuating indoor air quality models. In experiments with cigarette smoke as a source, the PAH
•onitor showed a high correlation with RSP concentrations measured using a piezobalance. The.
milaritv in PAH levels measured by the PAS but the difference in RSP concentrations for two types
(cigarettes (a Marlboro filter versus a Kentucky Research 2R1) indicate that the PAH monitor is
eusuring a particular subspecies of the particles, as it should be. and is not just responding ro changes
the mass concentration. The broad sensitivity range of the PAH monitor spanned three orders of
agnitudc, and its ruggedness and reliability suggest it is well suited for exposure model de%elopment
889
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and validation experiments in homes nnd other locations. Because the instrument is relatively small
and can be adapted tor bauery operation, it can also be used ir. xoior vehicle exposure field studies.
DISCLAIMER AND ACKNOWLEDGEMENT
This paper has been reviewed ir. accordance with the U.S. Environmental Protection Agency's
peer and administrative review policies and approved for presentation and publication. Mention of
trade names or commercial products does not constitute endorsement or recommendation for use. This
research wis supported in pari by the Tobacco Related Disease Research Program (Grain No.
2RT027") of the University of California.
REFERENCES
Byrtschcr, H. and Schmiat-Ott A. (19S4) "Surface i-nr.camcm of Scot Panicles in PhotoelectriCiilly Active Trace
Species," Science of the Tefal Environment, Vol 36, p. 2?3.
Carpenter, T.E., and Brenchley, D.L. (1972) "A Piezoelectric Inr.pacicr for Aerosol Monitoring," American
Industrial Hygiene Association Journal, Vol. 33, p. 51)3.
Daley. l'.S. (1974) "The Use of Piezoelectric Crystals in the Determination of Particulate Mass Concentrations ir.
Air," Ph.D. Thesis. University of Florida. Gainesville, FL
Daley, P.S., anci I.undgren, DA. i197S) "The Performance of Piezoelectric Crystal Sensors Used to Determine
Acroso! Muss Concentrations." American Industrial Hygiene Association Journal. Vol 36, pp. 518-532.
Funaw, E. (1994) personal communication on April 15, University of Las Vegas, Las Vegai. NV.
Niessncr, R, (1986) "Tne Chemical Response of the Photo-Electric Aerosol Sensor (PAS) to Different Aerosol
Systems," Journal of Aerosol Science, Vol. 12, No. 4. pp. 705-714.
Niessncr, R, Robers, W., and Wilbririg, P. (19S9) 'l aboratory Experiments en the Determination ofPolycvclic
Aromatic Hydrocarbon Coverage of Submicrometcr Particles by Laser-Induced Aerosol Photoemission.'
Anaiytical Chermtiy, Vol. 61, pp. 320-325.
Niessncr R. and WaleiuUik. G. (19591 "The Photoelectric Aerosol Sensor as a Fast-Responding ar.d Sensitive
Detection System for Cigarette Smoke Analysis," Presenilis 7. Analytical Ciwn'istrv, Vol. 333, pp. 129-133.
Ott. W„ Lungan, L , and Swiuer. P. (199?! "A Tims Series Model for Cigarette Smokinj Activity Patterns:
Model Validation for Carbon Monoxide and Respirahic Panicles ir. a Chamber and an Automobile," Journal of
Exposure Analysis and Environmental Epidemiciojy. Vol. 2, No. 2, pp. 175-200.
Olin. J.Cj. and Sem, G.J. (1971) "Piezoelectric Microbalancc far Monitoring the Mass Concentration of Suspended
Particles," Aimsspherie Environment, Vol 5. pp. 653-668
Olin. J.fi., Sem. G.J.. and O.ristenson, D.I.. C1970) "Piezoelectric-Electrostatic Aerosol Mass Concentration
Monitor," American Industrial Hygiene Association Journal, pp. 791-800.
Sem. G.J., ar.d Tsurubayashi. K. (1975) "A New Mass Sensor tor R:spirable Dust Measurement," American
Industrial Hygiene Association Joumai, pp. 79',-300.
Sem. G.J. Tsuiubaya.-hi, K., aito Homma, G.J. (1977) "Performanceof ihe Piezoelectric Microbalancc Respirabk
Aeroso; Sensor," American Industrial Hygiene Association Journal, Vol. 3S, pp. 580-588.
Wilson, N, Barbour. R K , Chr.ana. J.C., end Mtikund, R (in press) 'Evaluation of a Real-Time Monitor for Fine
Partxlc-Bound PAH in Air." Pohcyciic Aromatic Conwcitnds.
890
-------
400
300
200
RSP 1 vs. RSP 2
100
2C0
300
400
0
RSP 1 Concentration (ug/m3)
x 40
o
30
20 (-
PAH vs. RSP 1 PAH vs. RSP 2
100
200
0
300
400
RSP Concentration (ug/m3)
ure 1. Comparison of two piezobalances (RSP 1 and RSP 2) and comparison of FAH
and one piezobalance for the Marlboro filter cigarettes (Experiment A).
891
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1.400
RSF 1 vs. RSP
Not inc
_ 1,2DD
§• 1.000
2C0
400 600 800 1,000
RSP 1 Concentration (ug/m3)
1.200
1,400
50
at
30
ca
—i
20
10
PAH vs. RSP 1 Not Inc! PAH vs. RSP 2 Not Incl
0
0
200
400
600
1.000 1,200 1,400
RSP 1 Concentration (ug/m3)
Figure 2. Comparison of two piezobalances (RSP 1 and RSP 2) and comparison of
and one piezobalance for the Kentucky Researcn 2R1 cigarettes {Experime
892
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Measurement of Environmental Tobacco Smoke
Frank E. Jones
Consultant
32 Orchard Way South
Potomac, MD 20854
ABSTRACT.
A review of some measurements of environmental tobacco smoke
(ETS) is summarized. After several definitions, ETS is briefly
discussed and measurements of exposure to ETS are reviewed. Benzene
in smoking is discussed, including the quotation: "Smoking is by far
the largest anthropogenic source of background exposure to benzene."
Proxies, surrogates, tracers, and markers as indicators of ETS in both
personal and indoor space monitoring are treated.
INTRODUCTION.
Smoke from cigarettes, cigars, and pipes is one of the most
prevalent sources of pollution of air of particular concern indoors in
the workplace, in the hone, in restaurants, in public buildings, in
buses, on trains, etc. Pollutants from cigarette smoking are by far
the most prevalent of smoking pollutants. In this paper we shall
summarize a review (1) of some measurements of environmental tobacco
smoke.
DEFINITIONS
Environmental Tobacco Smoke.
Environmental tobacco smoke (ETS) is tobacco smoke in the
environment, to which smokers and nonsmokers (also referred to as
involuntary smokers and passive smokers) are exposed.
Mainstream Smoke.
Mainstream smoke (MS) is the complex mixture that exits from the
mouthpiece of a burning cigarette and is drawn through the tobacco
into the smoker's mouth when a puff is inhaled by the sir.oker.
Sidestream Smoke.
Sidestream smoke (SS) is the smoke emitted by the burning tobacco
between puffs (2).
ETS originates at the lighted tip of the cigarette, and exposure
Ls greatest in the proximity of the smoker (2). ETS exists in two
jhases: 1) the vapor phase; 2) the particulate phase. It is the only
source of nicotine in the environment (3). It can be a substantial
contributor to the level of indoor pollution concentrations of:
1) benzene
2) acrolein
3) N-nitrosamine
4) carbon monoxide
5) respirable particles.
Sidestream smoke contains greater amounts (than mainstream smoke)
f:
893
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1) nicotine
2) benzene
3) carbon monoxide
4) N-nitrosamine
5) ammonia
6) 2-naphthylamine
7) 4-aminobiphenyl
8) bcnz(a)anthracene
9) benz(o)pyrinc.
Sidestream smoke contains more free nicotine in the vapor phase
than does mainstream smoke.
MEASUKEMENT OF EXPOSURE TO FTS
Use of Diffusion Denuder Samplers.
Eatough et al. (4) used diffusion denuder samplers to collect
gas-phase acids and bases separately from particle-phase acids and
bases present in ETS. ETS was sampled from a 10-m3 unventialted
chamber in the initial experiment; a 30-rv unventilated chamber was
constructed and used for all subsequent chamber experiments. The
environmental chambers consisted of Teflon bags with Teflon sampling
manifolds at the bottom of the bag.
A cylindrical and/or annular diffusion denuder (with 0.8M
benzenesulfonic acid solution) was used to sample the atmosphere in
the environmental chamber for 1 to 4 hours. In some experiments, a
total hydrocarbon analyzer was used to monitor changes in gas phase
organic compounds.
The results indicated that the following gas-phase compounds raay
be unique to ETS in an indoor environment and may be suitable tracers
of tobacco smoke:
1) nicotine
2) 3-ethenylpyridine
3) myosmine
4) nitrous acid
5) pyridine.
EFFECTS OF TWEMl'Y-SCX ACTIVITIES.
In a controlled study, Wallace et al. (5) determined the effects
of each of 20 activities on personal exposure, indoor air
concentrations, and exhaled breath for volatile organic chemicals.
Two of the activities were:
1) tobacco smoking
2) passive smoking.
The breath levels of benzene and styrene in cigarette smokers'
breath were found to be about 5 to 10 times the level for nonsmokers
or pipe and cigar smokers.
The major source of exposure to benzene and styrene is mainstrean
tobacco smoke (6). Indoor levels of these two compounds in the
cigarette smokers' homes were slightly elevated.
The measurements of exhaled breath were useful in detecting
exposures from smoking that otherwise would not have been detected.
BENZEKE IK SMOKING.
Benzene is produced in the largest volume of any chemical that
has been causally linked to cancer in humans (7,8). In addition,, it
is a by-product of various combustion processes including the
894
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combustion of cigarettes. Approximately 8.5 billion kg of benzene is
emitted annually in the U.S. alone (9).
We quote now from a review of toxicology (10):
"Benzene is widely regarded as the most dangerous hydrocarbon
used in industry today. It is rapidly absorbed upon ingestion,
inhalation, or skin contamination and has a particular affinitiy for
nerve tissue Because of its toxic potential, benzene has been
banned as an ingredient in products intended for use in the home."
The Total Exposure Assessment Methodology (TEAK) studies (8)
found that benzene levels averaged 2 times higher in air people
breathe (personal air) than concentrations in outdoor air. Exposure
to benzene concentrations indoors was found to be greater than
exposure to the benzene level near gasoline stations in most cases
(9) . !LSmgking_is_by_far jthe_ largest^ anthropogenic source of
background exposure to benzene" (7).
It has been reported that smokers had benzene levels in expired
air 2 to 10 times higher than those of r.onsmokers (11). Also,
nonsmokers who lived with smokers or came in contact with smokers had
elevated levels of benzene in their breaths (11). About 3 times more
benzene is taken in daily by average smokers (20 cigarettes per day)
from smoking than from their exposure to background benzene
contamination.
NICOTINE
Intercomparison of sampling Techniques for Nicotine in Indoor
Environments.
An intercomparison of sampling techniques for nicotine in indoor
environments was made by Caka et al. (12). The sampling systems
studied used filter packs, annular denuders, sorbent beds, and passive
samplers. The intercomparison evaluated the precision and equivalency
of each of the techniques. Determinations were made of both airborne
gaseous nicotine and particulate-phase nicotine.
The four laboratories participating in the study v/ere: 1) a group
from Brigham Young U.; a group from Harvard U.; a group form the R.J.
Reynolds Company; and a group from the University of Massachusetts
Medical School and Yale U. The sampling techniques were: an annular
diffusion denuder; a filter pack sampling system; 2 passive sampling
devices; a Tenax semi-real-time sampler; a minianr.ular denuder; a
Millipore cassette; an XAD-IV sampler; a stainless steel diffusion
sampler; and an active sampler.
Determinations of total nicotine using the various sampling
systems were generally in good agreement. There was agreement among
samplers for determination of nicotine in the gas phase. The
precision of particulate-phase nicotine data was poor. Loss of
Darticulate-phase nicotine to the gas phase occurred in a filter pack
sampling system, and nicotine was lost from particles.
'ROXIES, SURROGATES, TRACERS, AND MARKERS.
A number of proxy, or surrogate, constituents have been
nvestigated in a number of studies as indicators of environmental
obacco smoke in both personal and indoor space monitoring. They have
Iso been referred to as markers or tracers. No single marker has
uantified accurately the exposure to each of the constituents of
moke over the wide range of environmental settings in which smoking
ccurs (2).
Markers should be chosen because of their accuracy in estimating
xposure and because of their relevance for the health outcome of
-------
interest (2). An ideal marker should be unique (or nearly unique) to
tobacco smoke, should be a constjtuuent of tobacco that is present, in
sufficient quantity that it can be measured even at low levels of ETS,
and should stand in constant ratio across brands ot cigartettes to
other tobacco smoke constituents or contaminants of interest (3).
Nicotine appears to be a promising tracer for ETS because of its
specificity for tobacco and its presence in relatively high
concentrations in tobacco smoke (?.). At a practical level, the
technology for measuring nicotine levels is available and accurate.
Nicotine volatilizes during dilution of sidestream smoke, so that it
occurs almost exclusively in the vapor phase (2). Almost all of the
nicotine shifts from the particulate phase in mainstream smoke and
sidestream smoke to the vapor phase in ETS (3). Tobacco is the only
source of nicotine, so the Nicotiana alkaloid is a specific indicator
for tobacco smoke pollution (3).
Identification of a Group of Potential Tracers of ETS.
The objective of a study by Benner et al. (13) was the detailed
chemical characterization of both the gas-phase and the particulate-
phase constituents of environmental tobacco smoke in order to identify
a group of potential tracers that would meet the National Academy of
Sciences recommended criteria:
1) uniqueness
2) ease of measurement
3) similarity in emission rates for different tobaccos
4) consistent ratios to ETS compounds of interest.
The characterization of particulate-phase ETS was described and
recommendations were made of several potential tracers which were
identified.
Based on the experimental results, the following particulate-
phase components of ETS were proposed as possible tracers:
1) nicotine and related compounds
2) solanesol
3) sterols and sterenes.
Other Potential Tracers and Markers.
Ogden and Kaiolo (14) concluded from their experiments that of
all the potential tracers that had been suggested for quantifying ETS
particulate concentrations in indoor environments, solanesol appeared
to be the best candidate; although more work needed to be done before
solanesol could be used as a routine tracer of ETS.
Chuang et al. (15) found in a field study that there were good
correlations between nicotine and quinoline and between nicotine and
isoquinoline. They recommended that quinoline and isoquinoline,
instead of nicotine, be used as ETS markers.
CONCLUSIONS.
Environmental tobacco smoke (ETS) exists in the vapor phase and
the particulate phase. It is the only source of nicotine in the
environment and is a substantial contributor to the level of indoor
pollution concentrations of benzene, carbon monoxide, and other
compounds.
The major source of exposure to benzene and styrene is mainstrea
smoke. The breath levels of benzene in cigarette smokers' breath wer
about E> to 10 times the level for nonsmokers or pipe and cigar
smokers. Nonsmokers who lived with snokers or came in contact with
smokers had elevated levels of benzene in their breaths. Average
896
-------
smokers (20 cigarettes per day) take in about three times more benzene
daily from smoking than from their exposure to background benzene
contamination. Again, "Smoking is by far the largest anthropogenic
source of background exposure to benzene."
A number of proxy, or surrogate, constituents have been measured
in a number of studies as indicators of environmental tobacco smoke in
both personal and indoor space monitoring. Nicotine appears to be a
promising tracer of ETS because of its specificity for tobacco and its
presence in relatively high concentrations in tobacco smoke. Nicotine
and related compounds, solanesol, and sterols and sterenes have been
proposed as possible tracers. Quinoline and isoquinoline have been
recommended as KTS markers, rather than nicotine.
REFERENCES
1. Jones, F.E.; Toxic Organic Vapors in the Workplace; Lewis
Publishers: Boca Raton, FL, 1994; pp 105-126.
2. The Health Consequences of Involuntary Smoking; A Report of
the Surgeon General. U.S. Department of Health and Human
Services, 1986.
3. Environmental Tobacco Smoke. Measuring Exposure and
Assessing Health Effects; National Research Council.
Washington, DC: National Academy Press, 1986.
4. Eatough, D.J.; Benner, C.L.; Bayona, J.M.; Richards, G.;
Lamb, J.D.; Lewis, E.A.; and Hansen, L.D. Environ. Sci.
Technol ¦ 1989 23, 679-687.
5. Wallace, L.A.; Pellizzari, E.D.; Hartwell, T.D.; Davis, V. ;
Michael, L.C.; and Whitir.ore, R.W. Environ. Res. 1989 50, 37-55.
6. Wallace, L.A.; Pellizzari, E.D.; Hartwell, T.D, ; Perritt, K.;
and Zigenfus, S. Arch. Environ. Health 1987 42, 272-279.
7. Hattemer-Frey, H.A.; Travis, C.C.; Land, M.L. Environ. Res.
1990 53, 221—232.
8. U.S. Environmental Protection Agency; National Emission
Standards for Hazardous Air Pollutants: Regulation of
Benzene, Fed. Res. 49f110):23¦478-23.455 (1984).
9. SRI International, Directory of Chemical Producers U. S.,
1987, 1988.
10. Bryson, P.D.; Comprehensive Review in Toxicology, 2nd ed.;
Aspen Publishers, Inc.: Rockville, MD, 1989; p 158.
11. Benzene: Occurrence in Drinking Water, Food, and Air; U.S.
Environmental Protection Agency: Washington, DC, 1983.
12. Caka, F.M.; Eatough, D.L.; Lewis, E.A.; Tang, H.; Hammond,
S.K.; Leadorer, B.P.; Koutrakis, P.; spengler, J.D.; Fasano,
A.; McCarthy, J.; Ogden, K.W.; and Lewtas, J. Environ. Sci.
Technol¦ 1989 23, 1148-1154.
.3. Benner, C.L.; Bayona, J.M.; Caka, P.M.; Tang, H; Lewis, L.;
Crawford, J.; Lamb, J.D.; Lee, M.L.; Lewis, E.A.; Hansen,
L.D.; and Eatough, D.J. Environ. Sci. Technol. 1989, 23.
688-699.
4. Ogden, M.K.; and Maiolo, K.C. Environ. Sci. Technol. 1989,
23, 4 29-435.
5. Chuang, J.C.; Mack, G.A.; Kuhlman, M.R.; and Wilson, N.K.
Atnos. Environ. 1991, 25B, 369-380.
897
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A Comparison of Smoking and Ncn-Smokir.g Areas
Private Homes and Bingo Halls
by
R.W. Bell, R.E. Chapman, B.D. Kruscbel and M.J. Spencer
Science and Technology Dranch. Onra/io Ministry of Environment and Energy
|4a Fir, 2 St Clwr Avenue Wtis*, Toronto, Ontario M4V 1LS
During the past 3 years, personal exposure studies were carried out in Windsor
and Hamilton as part of the "Cities of the Nineties'" program by the Ontario Ministry of
Environment and Energy. During these studies, airborne concentrations of 56 carbonyls
and other volatile organic compounds (VOCs) and 8 selected airborne trace metals were
measured. Since people usually spend less than 10/5 of their time outdoors and the main
objective of these studies was to obtain personal exposure profiles, these studies examined
the personal and general air quality in a variety of microenvironments including different
homes, offices, m/hotels, vehicles, garages and a variety of communal places such as
several bingo halls, a cafeteria, a retirement home, a swimming pool and a gymnasium.
Samples were also gathered during the volunteers' commuting to and from work.
When and where ever possible, personal air sampling was the preferred method of
Sampling with tile samplers being carried by the- volunteers during their regular day.
When this was not feasible nor practical, sampling was carried out in the major
microenvironments in which the volunteers lived, travelled and worked. For each
volunteer, a 24 hour "snapshot" personal air quality profile was compiled and together
with their time activity diary for these 24 hours, an exposure profile was computed.
Depending upon the compound class, the air was sampled at flow rates ranging
from 5 millilitres to 25 litres per minute and all samples were either acquired within the
volunteers' "breathing zone" or at a height of 1.5 metres in their microenvironments.
Throughout the study, concurrent outdoor sampling was conducted at the volunteers'
homes and if possible, at their offices. For determining volatile organic compound
concentrations in air, three-stage adsorption cartridge samples were used and these were
subsequently analyzed by thermal desorption and cryro-focusing at the head of a column
of a GC/FID-MSD (gas chromatograph fitted with flame ionization and mass selective
detectors) system. For the carbonyls, the sampling and analytical method involved the
derivitization with DNI'H (2,4-dinitrophenyl hydrazine) followed by HPLC separation and
detection of the hydrazone products. For (he trace metals, exposed Whatman 41 filters
were digested in a weak (5^) nitric acid and the extract was then analyzed by 1CP-MS
(inductively coupled plasma - mass spectrometry).
Environmental tobacco smoke (ETS) is aii important source of many of these
compounds and has been identified as the major, if not the leading cause of many indoor
air quality problems. During these studies, a questionnaire was given to each of the
volunteers and the answers allowed a correlation with smoking. Although our studies dealt
with only a small portion of the more than 4,700 identified ETS components, the results
indicated that isoprene would be an excellent marker or indicator for general air quality in
these microenvironments. This feature was highlighted during our investigations of bingo
halls: a place that allows potentially large exposures to ETS and a place where patrons can
spend many hours each day, several days a week. Differences between smoking and non-
smoking areas were more evident in the bingo halls than in the other settings and isoprene
was clearly seen in all situations as a primary gaseous component of F,TS.
898
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Windsor Personal Air Quality Study
Median Concentrations (at Home)
HSOttJdoor* Indi»Oft; : .Von-Sun'ikiri^ Hiuttocrs : Smntinp.
(IL2Satnpfe3) (22IIo««) (14iloa«s)
Windsor Personal Air Quality Study
Median Concentrations (Indoors)
80
'A !'
H Office H§M/HoEels I Mingo Hulls
(43 SanipJts) (17 Samples) ('39 S&ssples)
For die Windsor study, the
volunteers were all involved with
cither the academia, the government
or other environmental agencies.
For Hamilton, the volunteers were
randomly selected. In both studies,
the volunteers usually had 1 week
notice before samples were taken.
The volunteers tended to make their
homes more presentable during
sampling times and this was very
obvious from the Windsor results as
the isoprene concentrations in the
"Smoking" and "Non-Smoking"
homes were similar. In Hamilton,
there were definitive differences in
the isoprene, formaldehyde and
acetaldehyde concentrations; all
major constituents of ETS.
During one 24-hour period, 1
carbonyl, 1 trace metal and 7 VOC
samples were acquired in the
smoking section and 1 carbonyl, !
trace metal and 4 VOC samples were
acquired in the non-smoking section
of a very large (= 17,000 square
feet) bingo hall in Windsor. 1'his
bingo hall accommodated = 400
people regularly and from the data,
isoprene was shown to be a very
good air quality indicator for ETS.
Hamilton Personal Air Quality Study
Median Concentrations (at Uomc)
3D
IO
w i
J- ,«? J ^ .*¦> .v
,<**
/
I^Ou!,loo*? ISindoors : Noa-SmoIn;v. M Indoor* : Smoking
(4g&unp!esi (31 Hema) <2S Hwnet)
* Uii - M JC*nM
Avtrrtgc AiHx>rne Contaminant Ccj»cci!tiai:o:js
a
£> *
Claane's. Waxoa. fits.
« *
,, /
t/J
1;!/ eocrora
<•
c m
£*
1 »
c
yr,"
~.j ETS
* * ' Srnokir-S Section' " "*
A Bjys ({«.. :»V*g4ux
-------
Median Concentration Values: Windsor and Hamilton Personal Exposure Studies
1
j Airborne
| Compounds
Hamilton at Home
Windsor at Ilome
"Windsor - Indoors
Out
HNS
l!Sk
Out
HNS
HSk
Ofc
Bgo
1
j Isoprene
0.3
2.0
5.9
( 3.0
4.4
0.9
2.6
S6.3
i
1 Tricblorouiethanc
0.1
0.6
l.i
1.0
5.4
1.2
1.9
14.4
|
j Benzene
1.4
2.5
3.1
2.0
2.5
2.6
2.8
4.3
16.2
i
j Toluene
5.6
12.5
•7.5
6.9 J 11.9
25.0
8.4
9.5
50.2
Tetrachloroethene
0.3
t.O
0.9
0.9
0.6
3.3
i.4
0.7
2.6
j Formaldehyde
3.7
19.:
56.0
2.0
31.4
14.1
31.8
79.0
| Acetaldchyde
2.3-
1M
16.8
?..o
19.4
22.5
5.5
*.9.5
31.5
I
| Acrolein
3.9
6.3
5.0
I - n
73
0.3
2.7
:o.2
J Acetone
-
3.4 j 17.-7
26.0
*.0.6
10.2
4.0
Cadmium
0.7
0.4
0.3
0.6
0.4
0.3
0.4
2.5
4.:
Chromium
1.7
1.3
1.7
j .3
1.3
1.7
0.8
4.5
2.6
Manganese
33.6
4.0
A. 6
16.7
4.0
4.6
4.7
7.7
7.2
1 .t'iid
30.0
5.6
5.7
10.6
5.6
5.7
7.6
11.7
'M.6
Numhw of Sumples\
Homes
VOCs
48
32
25
112
22
U
43
17
39
Carbonyls
11
6
5
49
22
12
18
3
4
Trace Metals
31
15
15
46
22
15
17
3
4
Concentration Units: Volatile Organic* and Carbonyl - pfc'm3: Trace Metals - jjg/m3
insufficient data (eompmsnd detected »o fewer than 20*3- of the samples)
Out - Outdoors; HNS - Indoors Home. Non-Smoking; HSk - Indoors Home, Smoking
Ofc - Office; M'll - Motets and Hotels: Bgo - Bingo Ilalls
The outdoor samples were acquired either at the volunteers' homes or near their
offices. For the indoor samples, the average concentrations for the various airborne
compounds for each home were computed.
The Windsor information will be available in greater detail during the summer of
1994 when the Ontario Ministry of linvironment and Energy will be releasing the
following 9 reports on the Windsor Air Quality Study: Executive Summary, Emission
Inventory, Ambient Fixed Network Monitoring, Specialized Mobile. Air Monitoring,
Personal Exposure Survey. Soil and Garden Produce, Mathematical Modelling and Source
Apportionment, Health Effects Assessment and the Plain Language Summary.
-------
SESSION 22:
ANALYSIS OF POLAR
VOLATILE ORGANIC COMPOUNDS
-------
Intentionally Blank Page
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GC-MS Analysis of the Exhaled Breath Matrix
Joacium D. IHe.il and Andrew li. l.indstrom
Atmospheric Research and Exposure Assessment Laboratory
U.S. EPA
Research Triangle Park, NC
"Die organic components of the exhaled brealh matrix are considered
a non-invasive "window" into the blood gases. These compounds reflect normal
biogenic function, direct exposure to pollutants, and metabolites of such exposure,
(liven appropriate analysis and interpretation of the data, the organic fingerprint of (he
exhaled breath can become an important exposure and health assessment tool.
Standard gas chromalography-niass spectrometry (GC-MS) methods for measurement
of volatile organic compounds ill ambient air are not well suited to the breath matrix
due to the high carbon dioxide and moisture content and the wide variety and
concentration ranges of potential analytes. This paper presents a set of three
complementary analytical methods for GC-MS analysis specifically designed for
measuring Co. and VOCs in the exhaled brealh matrix. Example chroraatograms and
the performance of the methods will be discussed.
903
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Deactivating SUMMA Canisters for Collection and Analysis of
Polar Volatile Organic Compounds in Air
David Slwlow, Paul Sih'is, Andrew Schuyler, and Joe Slauffer
Restek Corporation
Uclleiontc, l'A
Joachim Plcit
AREAL (MD-44)
U.S. EPA
Research Triangle Park. NC
Michael Holdren
Handle Memorial institute
Columbus, Oil
SUMMA canisters are commonly used »s the collection medium for
whole air samples for the measurement of a variety of volatile organic compounds
(VOCs). The interior electropolished surface is inert for most non-polar compounds
even at trace levels, however, certain polar species (PVOCs) exhibit reduced
recoveries after storage. A surface deactivation process, referred to as
Silcosteel, has been developed wherein the interior of the canister is coated with a thin
layer of fused silica. Iri addition to the silica layer, a variety of chemical deactivations
can be used to increase the inertness of the surface for specific classes of VOCs.
Canisters with the standard electropolishcd interior surfaces were tested and compared
to those treated with the Silcosteel process and various deactivation layers. This paper
presents an explanation of the process and the results of the comparisons with
particular emphasis on the storage stability and minimum deteciible limits for PVOCs.
904
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CLEANLINESS OF COMMON AIR SAMPLING SORBENTS
FOR APPLICATION TO PHENOLIC COMPOUNDS MEASUREMENT
USING SUPERCRITICAL FLUID EXTRACT ION
James R. Bowyer
ManTech Environmental Technology, Inc., Research Triangle Park, NC 27709
Joachim D. Pleil
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
ABSTRACT
The trace-level measurement of phenolic compounds in the ambient air is complicated
by the acidic and polar nature of the compounds especially during recovery from the sampling
medium. Recently, supercritical fluid extraction (SFE) has been proposed as an alternative
extraction method to Soxhlet extraction or thermal desorption to achieve more efficient
recoveries. For such methodology to become practical, the candidate sorbents must first be
tested for stability and cleanliness under SFE conditions. This paper describes exploratory
research results of background contamination tests and cleanup properties of some common air
sampling sorbent media with respect to future application to phenolic compounds monitoring.
INTRODUCTION
SFE offers the following advantages over more traditional extraction methods such as
Soxhlet: 1) less expensive in terms of solvent purchase and disposal, 2) less harmful to the
environment, 3) less time consuming in sample preparation, and 4) equivalent or better
recoveries to traditional methods. It is for these and other desirable characteristics that SFE has
become an increasingly popular alternative to other extraction techniques.1"5 It is also makes an
attractive alternative means of cleaning and extracting sorbents used in air monitoring.
This work describes preliminary results of clean up properties and contaminants in these
sorbents. Also investigated were the effects of storage and exposure to ozone6 7.
EXPERIMENTAL PROCEDURE
Sorbents
The sorbents used in this work were Tenax-GC, Tenax-GR (Alltech Assoc., Inc.,
Deerfield, IL), XAD-2, and Carboxen 563 (Supelco, Bellefonte, PA). For SFE extractions the
following amounts of each sorbent were used: Tenax-GC, 0.2g; Tenax-GR, 0.4g; XAD-2, 0.4g;
Carboxen 563 , 0.6g. For Soxhlet extractions the following amounts of sorbent were used:
Tenax-GC, 0.6g; Tenax-GR, l.Og; XAD-2, 2.0g; Carboxen 563, l.Og.
SFE conditions
Extractions were performed using a system that included two Isco pumps (models 260D
and I00D), a Lee Scientific oven (model 501), stainless steel tubing, and deactivated fused silica
restrictors (Polymicro Technologies, Phoenix, AZ). A sample of each sorbent was placed in a
905
-------
clean 1 mL stainless steel extraction cartridge and extracted using 5% methanol (MeOH)/carbon
dioxide (COJ (v/v) at 50° C and 6000 psi. Each sorbent was statically extracted for 30 minutes
then dynamically for 0.5 -1.5 hours with collection of extracted material over 30 minute
intervals during this time. Flowrates of the supercritical fluid were approximately 1 mL/min.
Collection was in vials containing 2-3 mL of methylene chloride (MeClj). These solutions were
Chen reduced to a final volume of approximately 1 mL with a N2 flow.
Soxhlet conditions
Sorbent samples were weighed and placed in cleaned cellulose extraction thimbles. The
thimbles were then loaded in the Soxhlet extractors and the extractors were charged with 200
mL of extraction solvent. 5% ether/hexane (v/v) was used for the Tenax-GC and Tenax-GR
sorbents and McC12 was used for XAD-2 and Carboxen 563. The Soxhlet extractors were then
allowed to run for 16-18 hours: after which the solvent was rotary evaporated down to 3-4 mL
and then transferred to an evaporation vial for final reduction to 1 mL with a N, flow.
Analysis by GC/MS
Once the samples were blown down to 1 mL, an internal standard of 4,4'-dibromo-
1,1'biphenyl was added at a concentration of 1 ng/fiL. A 1-jtL aliquot was then inject into a
Hewlett-Packard GC/MS (HP5S90/HP5971A, respectively) equipped with an XTI-5 column
(Restek, Bellefonte, PA, 30 m, 0.25-mm i.d.,0.25-jxm d.f., catalog # 12223).
Temporal and chemical stability
Once the sorbents were cleaned, the SFE cartridges were sealed and allowed to remain
sealed for 4 weeks. This was done to determine if the sorbents remained clean once they were
extracted. At the end of this 4-week period the sorbents were once again extracted by SFE as
in the original clean up extraction above and the extract analy7£d.
Chemical stability was investigated by exposing the sorbents to ozone and extracting them
using SFE as above. The ozone exposure was 115 ppb for 18.5 hours at a flowrate of 1.3
L'min. with a relative humidity of 48-52% for the Tenax-GC. and Tenax-GR. For the XAD-2
and Carboxen 563, ozone exposure was 115 ppb for 16.0 hours at 1.5 L/min.with a relative
humidity of 40-509c. Again, the extracts were analyzed by GC/MS as above.
RESULTS
Initial "Clean-up" Extractions
As expected, analysis of the SFE and Soxhlet extracts from Tenax-GC, Tenax-GR, and
Carboxen 563 revealed significant amounts of impurities in the first sequential extracts.
However, the third sequential SFE extracts and the second sequential Soxhlet extracts showed
no detectable impurity except a consistent phthalate ester component. This compound was found
in all sorbents at varying levels but was greatly reduced with each subsequent extraction. It
should be noted that it was much easier and quicker to reach this level of "cleanliness" using
SFE (1.5-2 hours) than Soxhlet extraction (16-18 hours).
Analysis of the XAD-2 extracts revealed that this particular lot was surprisingly clean
given past experience with XAD-2. Previously, XAD-2 was repeatedly extracted but still
retained significant amounts of impurities. The impurities detected were the phthalate ester as
9(16
-------
in the other sorbents and an acid ester. The acid ester was only observed in the Soxhlet extract.
Subsequent extractions reduced the amount of these compounds in each extract.
During these initial clean-up extractions, it was noted that the hexane/ether mixture added
significantly to the background signal. Therefore, higher purity hexane was purchased and the
problem was eliminated.
The following observations were made after comparing the chromatograms of the
sequential SFE and Soxhlet extracts for the various sorbents.
Tenax-GC
• There were four primary contaminants associated with this sorbent. Two were
common to both the SFE and Soxhlet extracts and of the other two, one was found
in each.
Tenax-GR
• There were ten primary contaminants and they were components of both the SFE and
Soxhlet extracts at about the same relative levels.
XAD-2
• There were only two primary contaminants and one was associated with the SFE
extract and the other was associated with the Soxhlet extract.
Carboxen 563
• There were nine primary contaminants and only one was associated with the SFE
extract. The other eight were associated with the Soxhlet extract.
Temporal and Ozone Stability
Comments below pertain to chromatograms obtained from analysis of SFE extracts of
sorbent sealed for 4 weeks then extracted (•) and sorbent exposed to ozone then extracted (O).
Tenax-GC
o
Tenax-GR
Comparison of the third sequential extract before sealing and the first extraction after
being sealed revealed that there was no residual contaminants except for the ever
present phthalate ester mentioned above. Also, after a second extraction this peak
also became negligible.
Exposure to ozone did produce artifacts from the degradation of the Tenax-GC which
could be problematic if ambient measurements of compounds such as benzaldehyde
and acetophenone were being performed.
Comparison of the third sequential extract before sealing and the first extraction after
being sealed revealed that there was no residual contaminants except the phthalate
ester. Again this was removed completely after the second extraction.
90?
-------
o Only two artifacts were formed from exposure to ozone and at levels lower than for
Tenax-GC and did not include benzaldehyde nor acetophenone.
XAD-2 and Carboxen 563
• Comparison of the extracts before and after sealing showed no change in the sorbent.
o No effect on the sorbents was noted and no artifacts were extracted.
CONCLUSIONS
The following conclusions can be drawn from this preliminary study:
0 Since the two extraction methods can extract different components from the sorbents,
whichever method is used for clean up should also be used for the extraction of the
sample collected on the sorbent.
0 Tenax-GR is preferable to Tenax-GC because of its greater stability in O).
O XAD-2 and Carboxen 563 may be preferable to either Tenax type because of their
ease of cleaning and stability in Oj. Comparison of their collection and recovery
efficiencies to those of Tenax GC and GR will help determine this.
0 For preparation of small amounts of sorbents such as sorbent cartridges, SFE would
be preferable to Soxhlet extraction in terms of time and handling ease. A cartridge
could be filled, cleaned, used, extracted, and possibly reused, all without having to
remove and handle the sorbent thus minimizing the chance of contamination and
sample loss.
DISCLAIMER
The information in this document has been funded wholly or in part by the United Slates
Environmental Protection Agency under Contract No. 68-DO-0106 to ManTech Environmental
Technology, Inc. It has been subjected to Agency review and approved for publication.
Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
REFERENCES
1. Hawthorne, S.B. 1990. Analytical-Scale Supercritical Fluid Extraction. Anal. Chem.
62:633A-642A.
2. Hawthorne, S.B.,Miller, D.J., Langenfeld, J.J., Burford, M.D. 1992. Analytical-Scale
Extraction of Environmental Samples Using Supercritical Fluids. ACS Symposium
Series 508. Washington, DC: American Chemical Society.
3. Wright, B.W., Wright, C.W., Gale, R.W., Smith, R.D. 1987. Anal. Chem. 59:38-44.
908
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4. Chester, T.L., Pinkston, J.D., Raynie, D.E. 1992. Supercritical Fluid Chromatography
and Extraction. Anal. Chem. 64:153R-170R.
5. Engelhardt, H., Gross, A. 1991. Supercritical Fluid Extraction. Trends Anal. Chem.
10:64-71.
6. Pellizzari, E., Demian, B., Krost, K. 1984. Sampling of Organic Compounds in the
Presence of Reactive Inorganic Gases with Tcnax GC. Anal. Chem. 56:793-798.
7. Bunch, J.E., Pellizzari, E.D. 1979. Evaluation of Chromatographic Sorbents Used in
Air Pollution Studies. J. Chromatography. 186:811-829.
909
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Collection of Ambient Air Phenols Using an Anion Exchange Membrane
Marcia Nishioka and Hazel Burkholder
Batlclle Memorial Institute
Columbus, OH 43201-2693
Scott Reynolds and Nydia Burdick
SC Department of Health and Environmental Control
Columbia, SC,'
Joachim Ple.il
U.S. EPA
Research Triangle Park, NC
We have previously demonstrated the feasibility of collecting vapor phase
ambient air phenols by reversible chemical reaction with a solid sorbent. This sorbent,
similar to XAD-2, consists of a styrene divinylbenzene polymeric backbone with
chemically bound quaternary amine functional groups and exchangeable anion. The
smallest mesh siz.e used (21X1-400 mesh, 37-75 pars diameter) provided the highest
collection efficiency for diverse phenols at sampling rates of 100 mL/min. Detection
limits were about 1 ppbv (-7 //g/rrr).
We report here enhanced detection limits for ambient phenols using an anion
exchange membrane that allows high collection efficiency at 10 L/min sampling rate.
The membrane consists of 5 pan particles of the anion exchange resin enmeshed in a
Teflon microfibril matrix. This membrane is similar to "Empore" membranes, with the
addition of the anion exchange capacity. Sampling is accomplished using a 10.5 cm
(diameter) membrane and a General Metal Works PS-1 sampler. A Teflon-coated glass
fiber filter, spiked with dcutercd phenols, and placed ahead of the membrane, is used
to deliver these surrogate recovery standards to the membrane during the sampling.
Following sampling, membranes are shaken gently in an acidified mixture of methanol
and dichloromcthane. The extract is derivatized with BSTFA and analyzed using either
GC/FID or KI GC/MS. Analytical methodology allows detection at the 0.02 ppbv level
for 12 hrs of sampling (~ 0.1 wg/m3).
910
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Controlled Desorption Trap (CDT): A Water Management Technique
for Quantitative Analysis of Polar VOCs in Ambient Air
Sharon Keiss and Dick Jesser
Graseby/Nufcch
Durham, NC 27703-9000
Compendium Method TO-14 details the analysis of Volalilc Organic
Compounds (VOCs) in ambient air using cryogenic preconccnlration Cor sample
enrichment. These (race level organics require preconccnlration of volumes greater
than 50ml to provide a sufficient sample mass to an analytical detector.
When working with high humidity sample volumes of 50ml and gtualcr, water
management becomes critical. Compendium Method TO-14 specifics the Nalion™
semi-pcrmeablc membrane to reduce water vapor in (he sample stream during
cryogenic concentration. The same mechanism responsible for this effective
dehydration of the sample compromises tecoveiies of polar species. Consequently,
alternate water management techniques arc necessary when polar compounds are
analyzed.
The CDT is effective as a water management techniques since it allows
volatile organics, collected on a primary cryotrap, to vaporize at a temperature that
limits the partial pressure of water vapor. Temperature control of the cryotrap and the
total volume of the desorption gas are essentia? parameters in optimizing CDT. A
secondary cryotrapping step is necessary to refocus the slowly desorbed sample
prior to injection lo a GC or GC/MS.
The analytical system consists of the Grascby/Nutech 3550A Cryogenic
Concentrator, the 354A C.'ryofocusing Accessory and the HI' 5y?l GC/MS. Some of
the classes of compounds investigated using this application include alcohols, ketones
and ethers.
The effectiveness of the CDT will be compared with analyses using (a) no
water management and (b) the Nation dryer.
911
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A Comparison of Concentration Techniques tor the Analysis of
Polar Compounds in Canister Samples
1). li. C.ardin andJ.T. Deschenes
Knicch Laboratory Automation
950 Enchanted Way #101
Simi Valley, CA 93065
The analysis of Polar Volatile Organic Compounds (PVOCs) in ambient air
bv GC/MS requires sample preconcentration to achieve U.l ppb detection limits.
Necessary sample, volumes can exceed 300 cc resulting in the co-collection of
approximately 3-6 td of water, depending on the humidity of the sample. This
much water will degrade column performance and will cause signal attenuation in
bcnchtop mass spectrometers making quantification of target analvtes difficult.
Although most of the water vapor can be eliminated by passing the sample through a
Nafion Dryer, such an approach usually results in loss of the polar VOC fraction in
the sample due to passive and/or active interaction with the dryer.
Two 3-Stagc preconccntraton techniques have been previously reported which
allow both polar and non-polar VOCs to be quantified by eliminating most of the
water before injection into a GC/MS. These techniques, namely Automated
2-Dimensional Chromatography (A2DC) and Microscale Purge & Trap (MP&T), both
eliminate water and CO, in the sample before GC/MS injection to improve detection
limits and quantitation accuracy.
A concentration system utilizing yet a third water management technique called
Cold Trap Dehydration (CTD) will be presented. Using this technique, water can be
subtantiallv eliminated without loss of polar VOCs of interest. C02 is also eliminated
before GC/MS injection resulting in superior chromatographic performance and a more
consistent GC/MS response for the extremely light VOCs. The prcconccntralor uses
the same hardware trapping configuration for Cold Trap Dehydration as it does for
Automated 2-Dimensional Chromatography and Microscale Purge & Trap, and can
select any one of the three applications under software control. To determine which
approach is best for TO 14 and CAAA Title III compounds, all three water
management procedures will be examined and compared. Data will he presented
showing detection limits and %RSD's from the analysis of PVOCs in canisters using
the 3-stage Entech 2000/2016CM Automated preconcentration system and au HP 5972
GC/MS.
912
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SESSION 23:
SEMI-VOLATILE ORGANIC COMPOUNDS
-------
Intentionally Blank Page
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Method Validation Program for the Long Duration Sampling of
PCDDs/PCDFs in Ambient Air
Bruce E. Maisel, Gary T. Hunt, and Marilyn P. Hoyt
ENSR Consulting and Engineering
Ac Ion, MA 01720
Newt Howe and I.ouis Scarj'o
Connecticut Department of Environmental Protection
Hartford, CT
A method validation program was completed to assess the technical viability
of extended, long duration sampling periods (15- and 30-day) for the collection of
PCDDs/PCDFs in ambient uir in lieu of the 48-hour sampling periods typically
employed. This long duration approach, if successful, would provide measurements
data more representative of average ambient PCDDs/PCDFs levels on an annual basis,
and hence provide enhanced support of the 1.0 pg/m3 annua! ambient standard for
PCDDs/PCDFs (expressed as 1987 EPA toxic equivalents) required by Connecticut
regulation.
The method validation program utilized nine collocated "PUF" samplers which
were operated for 15-day and 30-day periods during each of two seasonal monitoring
campaigns (winter and summer). Each "PUF1' sampler was outfitted with a Teflon
coaled glass fiber filter and polyurethanc foam (PUF) cartridge for the collection of
particulate-associated and vapor phase PCDDs/PCDFs, respectively.
Samples were analyzed using high resolution gas chromatography/high
resolution mass spectrometry (HRGC/HRMS) based on EPA Method 8290. Each
"PUP' cartridge consisted of two foam halves; the top half PUF and filter were
analyzed as a single sample separately from the bottom half PUF section. This
approach provided an assessment of analyte breakthrough using the sampling system
for large sample volumes of approximately 4,(XX) mJ and 8,000 m3 for the 15-day and
30-day sampling periods,
respectively.
915
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Effect of Combustion Temperature 011 the Atmospheric Stability of
Folychlorinated Dibenzo-p-dioxins and Dibcnzofurans
David M. 1'ennise and Richard M. Kamens
Department of Environmental Sciences anil Engineering
I Iniversity of North Carolina
Chapel Hill. NC 27599-74(X)
Atmospheric emissions of polychlorinated dibenzo-p-dioxins and
dibenzot'urans (PCDDs and PCDFs) are likely to increase in the future due to an
increase in municipal and hazardous waste incineration. There is little information
regarding the atmospheric stability of PCDDs and I'CDFs. In this study PCDDs and
PCDFs were generated from the combustion of a mixture of pentachlorophenol,
polyvinyl chloride pipe shavings, and wood chips treated with pentachlorophenol.
These emissions were injected into outdoor Teflon film chambers and aged in sunlight
under typical atmospheric conditions. Incineration experiments were conducted using
'low temperature'' combustion (4(XJ-47()°C range) and "high temperature" combustion
(670-800°C range). Concentrations of PCDDs and PCDFs were determined over time
by collecting both particulate and vapor phase samples. These compounds were found
to exist primarily in the particulate phase. Based on previous results with
polybrominated dioxins and fuians, we expect particulate phase PCDDs and PCDFs to
slowly degrade over periods of hours in the "low temperature" experiments. However,
in "high temperature" experiments, we expect particulate phase I'CDD and PCDF
emissions to be stable. Differences in the morphology and chemical composition of the
combustion particles generated can explain the differences in the Atmospheric
stability of particle associated organics produced from the "low temperature" and "high
temperature" experiments. Previous results show that incinerators operating near 450°C
can generate particulate phase brominated dioxins and iurans and PAH emissions with
atmospheric half-lives of 1-2 hours. These observations also indicate that the
corresponding emissions from incinerators operating near 8(X)°C will have much
longer half-lives, allowing for the possibility of long distance transport. If the same
observations ate made for PCDDs and PCDFs, this dependence on combustion
temperature must be considered when evaluating the potential exposure to toxic
organic compounds emitted from waste incinerators.
916
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Modeling the Mass Transfer of Semi-Volatile Organics
in Combustion Aerosols
Jay R. Odum and Richard M. Kamens
Department of Bnvironmcntal Sciences and Lnginccring
University of North Carolina
Chapel Hill, NC 27599-7400
The atmospheric transport" and fate of airborne organic compounds are highly
dependent upon which phase or phases (i.e., gas or particle or gas/particle) the
compound exists. Semi-volatile organics partition into both gas and particle phases and
this partitioning is a function of the compound's vapor pressure, liie amount of
available surface area, and the ambient temperature. Over the last 10 years, efforts to
predict atmospheric semi-volatile partitioning have been primarily hased on
equilibrium theory (June 1977: Pankow 1987, 1991. 1992; Bidclman 1986, 1988).
However, recent discoveries in this area suggest that full partitioning equilibrium may
rarely be achieved in (he atmosphere. Therefore dynamic mass transfer models, rather
than equilibrium models, may be better suited to predict semi-volatile partitioning.
Recently Rounds and Pankow (ES&T 1990, 1993) developed a radial
pore-diffusion model to simulate the muss transfer of semi-volatile organics in and out
of combustion aerosols. Preliminary results from their model and other recent
discoveries suggest that many types of combustion aerosols may be coated with a
liquid organic layer and that diffusion of semi-volatile organic* through this layer
impedes rapid mass transfer of these compounds. Therefore a radial diffusion model
was developed to describe the mass transfer of semi-volatile organics into and out of
combustion aerosols. The model combustion aerosol consists of a solid carbon core
that is surrounded by a viscous, liquid-like, organic layer. Diffusion takes place
only within the organic layer and is controlled by mass transfer at the particle surface.
Modeling of semi-volatiles requires the tuning of two separate parameters: a diffusion
coefficient and a surface mass transfer coefficient. Preliminary testing of the model on
the uptake of dcuterated pyrene by diescl exhaust aerosol at 25rC suggests that
diffusion coefficients for PAH are on the order of 10":5 cm2/sec and that surface
mass transfer coefficients for pyrene are on the order of 10"' cm'see.
917
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Experimental Observations of Non-Equilibrium Gas-Particle
Partitioning of PAHS in an Outdoor Smog Chamber
Dana L. Coe and Richard M. Kamtns
Department of Environmental Sciences and Engineering
University of North Carolina
Chapel Hill, North Carolina 27599-7400
To study non-equilibrium gas-particle partitioning of various PAHs,
three specially designed smog chamber experiments were conducted (October 1993,
January 1994, and February 1994). Automobile diescl exhaust was injected for live
minutes into a 190 nr Teflon film chamber and allowed to age during the night at
temperatures below 15 degrees Celsius. A large denuder system was utilized during
the injection period in order to remove PAH vapors from the injection stream. Thus,
PAH-laden particles were observed id off-gas in the near absence of vapor phase
PAHs during the initial stages of the- 8-hour experiments. The large denuder was
designed as a parallel plate system, made of activated charcoal impregnated filters. It
was characterized to remove greater than 90% of PAH vapors from the diesel injection
system. During the experiments, air samples were collected in the chamber at
twenty-minute intervals for the first two hours, and hourly thereafter. The sampling
system consisted of an XAD-4 coated annuIaT denuder, followed by a quartz-fiber
filter, which is then followed by a second annular denuder. Sample extracts were
analyzed on Hewlett-Packard GC/MS. Results from these experiments are compared to
output from a radial diffusion computer model, detailed in another paper ("Modeling
the Mass Transfer of Semi-Volatile Organics in Combustion Aerosols" by Jay K.
Odum and Richard M. Kamens).
918
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Use of the Phenanthrene to Benzo(e)pyrene Ambient Air Ratio as an
Indicator for the Source of Polycyclic Aromatic Hydrocarbons
Andre Germain, Sonia Ringuette and Jean Tremblay.
Environment Canada, Environmental Protection Service, Quebec Region
1179 de Bleury Street,
Montreal (Quebec)
Canada
H3B 3H9
ABSTRACT
Polycyclic Aromatic Hydrocarbons (PAH) arc emitted by many industrial, domestic and
natural sources. In 1990, the principal sources of PAH for the Province of Quebec were
primary aluminum smelters (858 t), residential heating with wood (162 t), forest fires
(148 t) and transportation (33 t). A sampling program was developed to measure PAH
levels in ambient air at different locations influenced by these sources. The highest
concentrations of PAH in ambient air (470 ng/m3 geometric mean) were measured near
primary aluminum smellers using Horizontal Stud Soderberg technology. Areas influenced
by wood heating (157 ng/mJ winter geometric mean) and transportation (80 ng/rn"' geometric
mean) had lower total PAH concentrations. Ratios of ambient air concentration for
phenanthrene/benzo(e)pvrene were lower in samples collected in the surroundings of the
primary aluminum smelters (7-14), whereas high ratios were observed for residential
heating with wood and transportation (20-45). The use of this ratio was found to be a good
indicator for PAH originating from primary aluminum smelters.
INTRODUCTION
In 1989, Environment Canada began a sampling program to characterize the ambient air
levels of polycyclic aromatic hydrocarbons (PAH) and to use the data obtained to assess
their toxicity, as defined by the Canadian Environmental Protection Act (CEPA). This
program was done in parallel with an estimate of their releases to the Canadian
environment. During the summer of 1991, many forest fires occured in the Province of
Quebec, including some that were of concern for the population living near the shore of the
St. Lawrence River estuary in the city of Baie Comeau. In addition to the danger (ires
represent, concerns regarding the impact of those fires on air quality were expressed.
Polycyclic aromatic hydrocarbons were measured, in cooperation with the Quebec Ministry
of the environment and wildlife (MEF) and the city of Baie Comeau. High levels of PAH
were measured but could not be attributed to forest fires (Naturam, 1991). In order to
confirm this, additional sampling was undertaken during winter when forest fires had
ceased. Again, high PAH values were measured, fn order to identify the origin of PAH,
ratios between compounds can be looked at (Daisey et ah, 1986; Lavalin, 1988). We
examined different ratios for the locations at which we sampled. The areas surveyed were
919
-------
influenced by activities from industrial sources (mainly aluminum smelters using different
electrolysis technologies), residential wood heating, forest fires, and traffic.
EXPERIMENTAL
Ambient air sampling was carried out using a General Metal Works model GMWI^-
2000 II High Volume Air Sampling System, modified as per Environment Canada
specifications [e.g. addition of Polyuretbane foam (PUF) cannister and dry gas meter]
(Dann, 1987). Cleaned teflon-impregnated glass fiber filters (Pallflex Emfab Teflon Coated
Glass Fibre TX40H120WW; 8 x 10 in.) and cylindrical polyuretbane foam (9x15 cm) were
used to collect PAH in two particulate and gazeous phases.
The samples were collected at different locations and seasons every 6th day over a
24-h period, in accordance with the National Air Pollution Sampling Network (NAPS).
Samples were sent to laboratory in a cooler at 4° C and stored at -20° C until analysis.
Filters and PUF were spiked with seven (7) deuterated compounds [Ds-naphlhalene; D10-
Acenaphtene; D,0- Anthracene; Din-Pyrene; Dl2-Benz(a)anthracene; D12-Benzo(a)pyrene; D,,-
Benzo(ghi)perylene] before soxhlet extraction for 18-h with benzene and cyclohexane
respectively. Extracts were passed through a 20-cm silica gel clean-up column and analysed
with a Hewlett Packard model HP-5971 MSD GC-MS in Selected Ion Monitoring (SIM)
mode, a SPB-5 (Supelco) fused silica capillary column (30 m x 0.32 mm i.d.) and
temperature programming (80° C to 300° C). Quantification was done using an internal
standard (Dm-Fluoranthene) (Novalab, 1992).
RESULTS
Table 1 presents geometric means (g.m.) of the different PAII measured in ambient
air in the Province of Quebec. Highest concentrations of total PAH were measured in
Jonquiere (457 ng/m3, g.m.) and Shawinigan (263 ng/iir, g.in.), where aluminum smelters
using the Horizontal Stud Soderberg (HSS) process are located. Baie Comeau, near which
forest fires occured during the summer of 1991, had the third highest geometric mean
(165 ng/m3). There is also an aluminum complex in Baie Comeau using the Vertical Stud
Soderberg (VSS; 2/3 of its production capacity) and Pre-baked (PB; 1/3 of its production
capacity) processes. Based on stack sampling and measurements of fugitive emission, the
estimated PAH emissions for these processes (HSS, VSS and PB) are 2.05, 0.23 and
0.0013 kg/tonne of aluminum produced (LGL, 1993). In a residential area or Montreal
(R.l).P.), total PAH concentration in ambient air was found to be 102 ng/m3 (g.m.),
whereas in Sept-Ues, the concentration was found to be 69 ng/m3 (g.m.). These two areas
are known to be impacted by residential wood heating. These values were in the same
range as those measured at a station located 100 m off two major highways, in Montreal
(D & D; 79 ng/m3 g.m.).
The measurement made by Environment Canada in Jonquiere showed high ambient
air PAH concentrations were measured when the sampling station was downwind of the
aluminum smelter for most of the day (I^avalin, 1992; Germain and Bisson, 1992). It was
found that ratios of the different compounds with respect to benzo(c)pyrene [B(e)P] were
920
-------
of the same order of magnitude for the samples collected at the roof vents of the aluminum
smelter (Houle, 1986) located in Jonquiere and for the daily ambient air results when total
PAH were elevated (> 1000 ng/m3). The phenanthrene/B(e)P ratios were 2.7 (n - 3) and
6.2 (n = 45) respectively. Similar ratios were observed at stations near aluminum smellers
in Shawinigan (4.8; n = 14) and Baie Comeau (8.0; n = 7) when total PAH where greater
than 1000 rig/m3.
In residential area5 of Montreal CR.D.P.) and Sept-Des, influenced by residential
wood heating, the phenanthrene/B(e)P ratio calculated with the mean concentrations are
greater (21,2 and 45.1 respectively) than those observed in areas influenced by aluminum
smelters. A similar ratio (41.7) is also observed for the data obtained from the Montreal
station (D & I)) representing heavy traffic.
In Baie Comeau, the results from individual samples seem to indicate that high total
PAH levels in ambient air were measured when the sampling station was downwind of the
aluminum smelter whereas lower levels were more associated with wood combustion (either
residential or forest fires).
Two other ratios were examined: fiuoranthene to pyrene and fluorene to pyrene.
Based on the ratios calculated with the geometric mean of those compounds,
fluorene/pyrene ratios calculated for areas influenced by aluminum smelters ranged from
0.1 to 0.5, whereas they ranged from 1.1 to 1.4 in those areas where transportation and
wood burning are predominant. The fluoranthene/pyrene ratios did not show large
differences, ranging from 1.3 to 1.6 (stations near aluminum smelters) and from 1.0 to 1.3
(transportation and wood burning).
CONCLUSION
Hie levels of PAH in ambient air are strongly dependent on the source of emissions.
The use of the phenanthrene/B(e)P ratio can be used to indicate If PAH measured in
ambient air originate from an aluminum smelter, but they can not be used to discriminate
between residential wood burning or traffic. TTie fluorene/pyrene ratio may represent
another alternative for identifing the origin of PAH. In both cases, collection of air
samples must be done with filter and PUF, in order to retain phenanthrene, fluorene,
fiuoranthene and pyrene which are present mainly in the gaseous phase.
ACKNOWLEDGBMENTS
This work would not have been possible without the participation of a number of
people, including personal from MEF, and field operators. Special thanks are due to Tom
Dann from Environment Canada, for his valuable contribution in the project.
921
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REFERENCES
Daiscy, J.M.; Cheney, J.L; Lioy, P.J. JAPCA 1986 3*5:17-30.
Dann, T.;. Sampling of Polycyclic Aromatic Hydrocarbons in Ambient Air. Environment
Canada, Pollution Measurement Division, Technology Development & Technical Services
Branch, River Road Environmental Technology Centre, Ottawa, Ontario. Unpublished
Report. 1987. 13 p.
Germain, A.; Bisson, M.; "Mesure d'hydrocarbures aromatiques polycycliques dans 1'air
ambiant au Quebec (Canada)," in Proceedings of the 5th Conference on Toxic Substances,
Montreal, April 1-2,1992. pp 47-57.
Houle, G. Mise au point d'une mithode d'ichantiUonnagepour la mesure des hydrocarbures
aromatiques polycycliques (HAP) provenant de sources fixes. Quebec Ministry of the
Environment, Air Control Branch, 1988. 29 p. + appendices.
Lavalin. Inventaire des sources d'hydrocarbures aromatiques polycycliques au Quebec.
Report prepared for Environment Canada, Quebec Region, Montreal. 1988.
Lavalin. PAH Levels in Ambient Air in Quebec: Fall 1990-Winter 1991 Sampling Program.
Prepared for Environment Canada, Quebec Region. 1992. Unpublished Report.
LGL (Lalonde, Girouard, Letendre and Associates). PAH Emissions into the Canadian
Environment -1990. Prepared for Environment Canada, Quebec Region, Montreal. 1993.
Naturam. Rhultats de la campagne d'ichantiUonnage d'air d Baie Comeau suite aux
incendies forestiers de fete 1991. Report prepared for the City of Beau Comeau. 1991.
24 p.
Novalab. Determination des teneurs en hydrocarbures aromatiques polycycliques dans I'air
ambiant de Baie Comeau, Beauharnois, Jonquiire et Shawinigan. Report submitted to
Environment Canada, Quebec Region, Montreal. 1992.
922
-------
Table 1. PAH geometric mean concentrations (ng/m*) for different locations in Quebec (Canada).
Jon-
Shawi-
Baie
Beau-
Later-
Cap-
Montreal
Montreal
Sept
quiere
nigan
Comeau
haraois
riere
Madeleine
(D & D)
(RDP)
lies
Number of samples
121
62
39
30
7
16
21
31
24
Sampling period
89-93
89-93
91-93
91-93
1991
89-90
1991
89-90
90-91
Acenaphthylene
2.9
2.4
0.5
0.8
0.1
8.9
3.1
7.8
2.6
Acenaphthene
8.7
3.8
6.3
2
0.1
0.6
1.5
2.1
0.6
Fluorvne
11.2
4.1
5.7
3.6
0.1
14.4
6.2
9.3
5.4
Phenanthrene
104.7
52.5
47.9
26.3
0.4
51.3
30.2
30.9
23.4
Anthracene
4.3
5.1
4.1
2.2
0.1
3.6
2.6
4.4
4.0
Fluoranthene
74.1
41.7
24.0
15.1
0.2
9.8
6.2
9.8
6.5
Pyrene
51.3
31.6
15.1
10.2
0.1
10
5.5
7.6
4.8
Benzo(a)Fluorene
8.7
5.0
1.9
1.4
0.1
1.9
0.9
1.7
1.4
Benzo(b)fluonene
2.7
1.8
1.1
0.8
0.0
0.4
0.3
0.7
0.5
Benzo(gh i)fluoranthene
3.2
2.1
1.0
0.8
0.0
1.4
0.8
1.0
0.7
Denz(a)anthracene
7.2
3.2
1.7
1.0
0.0
0.7
0.4
1.1
0.7
Clirysene
24.6
12.6
7.6
5.9
0.1
4.2
1.2
2.5
1.3
7,12-DlmethyIbenzanthracene
0
0
0
0
0
0
0
Bcnzo(b+k)fluoraothene
34.7
15.8
8.5
6.9
0.1
4.1
1.7
3.5
1.4
Benzo(e) pyrene
14.8
6.6
3.3
2.9
0.1
2.3
0.7
1.5
0.5
Benzo(a)pyrene
5.1
2.0
1.7
0.6
0
0.3
0.4
0.8
0.4
Perylene
1.4
0.5
0.7
0.1
0
0.1
0.3
0.8
0.1
3-Methylcholanthrene
0
0
0
0
0
0
0
0
0
Indeno(l,2,3-cd)pyrene
5.7
2.7
1.1
0.9
0.1
1.5
0.4
1.3
0.4
Dibenz(a,h)anthracene
1.8
0.6
0.3
0.2
0
0.6
0.3
0.6
0.1
Benzo(b)chrysene
1.1
0.1
0.1
0.0
0
0.3
0
0.3
0.1
Benzo(ghi) perylene
5.7
3.0
1.5
1.1
0.1
2.0
0.8
1.2
0.3
Anthauthrene
0.6
0.1
0.1
0.1
0
0
0.4
0.6
0.1
Coronene
1.6
0.4
0.0
0.4
0
1.0
0.8
0.7
0.3
Dibenzo(a ,i) pyrene
0
0
0
0
0
0
0
0
0
Total PAH
457
263
166
105
13
162
79
102
69
-------
Table 2. Summary of ratios calculated with geometric mean
of ambient air PAH results.
Phe/BeP1
Fluot/Pyr*
Fluo/Pyr3
Jonquiere
7.1
1.5
0.2
Shawinigan
7.8
1.3
0.1
Baie-Comeau
14.5
1.6
0.4
Beauharnois
9.1
1.5
0.4
Laterriere
4.7
1.6
0.5
Cap-Madeleine
21.9
1.0
1.4
Montreal (D&D)
41.7
1.1
1.1
Montreal (RDF)
21.2
1.3
1.2
Sept-lies
45.1
1.3
1.1
1: Phenanthrenc/Benzofe)pyrene
2: Fluoranthene/Pyrene
3: Fluorenc/Pyrene
924
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Polycyclie Aromatic Hydrocarbons in House Dust
and Track-In Suil in an Eight-Home Study
Jam ( Chuang, Patrick J. Callahan, Vanessa Katona,
and Sydney M. Gordon
Batiellc
505 King Avenue
Columbus, Ohio 43201-2693
Robert G. Lewis and Nancy K. Wilson
Atmospheric Research and Exposure Assessment Laboratory
U.S. EPA
Research Triangle Park, NC 27711
The analytical method to determine polycyclic aromatic hydrocarbons (PAH)
in house dust and soil samples was validated. The method consists of sonication with
10 ml, of hexanc (C6) for two 30-minutc extractions, and analysis of the Cfi extract by
gas chromatography.'mass spectrometry (GC/MS). An eight-home pilot field study was
conducted in Columbus Ohio before and aflet the 1992/1993 heating season to obtain
concentration profiles of PAH in house dust and track-in soil, and to determine
whether track-in ol outdoor soil residues is an important source of PAH in house dust.
A total of 1 y I'AH, ranging from 2-ring naphthalene to 7-ring coronene, was
monitored. The sum of the concentrations of all target PAII in the house dust samples
evaluated in this study ranged from 41 to 580 ppm and from 25 to 310 ppm in the
samples collected during October 1992 and April 1993. Higher conciliations were
observed in entiy way suil samples and the sums of the concentrations of target PAH
ranged from 68 to 4000 ppm and 58 to 5500 ppm in samples collected before
(October 1992) and after (April 199.3) the winter heating season, respectively. The
sum of the concentrations of PAH in the pathway soil samples varied from 3.0 to 1200
ppm in samples collected before the heating season. The sum of the concentrations of
PAH ranged from 0.58 to 610 ppm and from 0.63 to 63 ppm in pathway soil and
foundation soil samples collected after the heating season, respectively. The
concentrations of most 4- to 6-ring PAH, the sum of all target PAH, and the sum of
PAH that arc probable carcinogens in house dust correlated well with the
corresponding levels in the enlryway soil. However, there was no correlation
between the PAH concentrations in house dust, and in pathway soil, nor was any
relationship found between house dust and foundation soil.
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SESSION 24:
GENERAL PAPERS
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Future Research Directions for the Great Waters Program
Melissa W. McCullough
OAOPS
U.S. EPA
Research Triangle Park, NC 27711
The J 990 Report to Congress contained Section 112(m), requiring the
assessment of the deposition of air pollutants to the Great Lakes, Lake Ciiamplain,
Chesapeake Bay and coastal waters. This program, called the Great Waters program, is
required to have a report to Congress in three years and every two years thereafter.
The first Report to Congress is to be released this spring (paper by Amy Vasu is
describing the report).
With the completion of the first Great Waters report and the ensuing
discussions within the Agency, it is now appropriate to assess the future needs and
direction of the program. We know now where we stand in terms of the state of the
knowledge, and what kinds of efforts are needed to provide a comprehensive picture
of atmospheric deposition of toxics to aquatic ecosystems. Given that the problem is a
vastly complex one, and that research in this area is extremely expensive, the Agency
must now determine where efforts are best spent to collect the most important
information to meet the mandate of Section l!2(m) of the Clean Air Act.
The Agency is working on a program strategy to target those most-effective
efforts. This paper will describe the strategy and the rationale for its design.
929
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Scientific Findings and Regulatory Recommendations of the
1993 Great Waters Report to Congress
Amy Vcisu
U.S. EPA
OAOPS
Research Triangle Park, NC 27711
As a requirement of Section 112(m) of the 1990 Clean Air Act, the
Enviionmonlal Protection Agency (EPA) must submit a report to Congress on the
deposition ot air pollutants to the Great Lakes, Lake Charaplain, Chesapeake Bay, and
coastal waters (i.e., "the Great Waters") by November 15, 1993 and every two years
thereafter. The 1993 report to Congress includes scientific, findings on the following:
(1) human health and environmental effects associated with deposited air pollutants,
(3) atmospheric loadings of pollutants to the Great Waters, and (3) sources of the
pollutants being deposited to the Great Waters. Findings of the report indicate that
significant adverse effects on human health and wildlife have been caused by
exposure, especially through fish consumption, to persistent chemicals that
bioaccumulatc. Atmospheric deposition is shown to be a major contributor of mercury,
PCBs, and other persistent chemicals that bioaccumulate. Emissions from local as well
as distant sources may contribute to pollutant loadings to water bodies. The scientific
findings provide support for the regulatory recommendations of the report. These
recommendations include taking actions under the Clean Air Act (e.g., early
completion of emission standards for sources of Great Waters pollutants) and under
other Federal authorities (e.g., the Federal Insecticide, Fungicide, and Rodcnticide
Act), and continuing research efforts in areas where critical data gaps exist.
930
-------
Laser-Induced Photofragmentation/Photoionization Spectrometric Detection
of NO, N02, HN03 and CH3N02 Under Atmospheric Conditions
J.B. Simconsson, C.W. Lemire and R.C. Sausa
US Army Research Laboratory, AMSRL-WT-PC
Aberdeen Proving Ground, Maryland 21005-51)66
ABSTRACT
leaser-induced photofragmentation/photoionization (Pi-VPI) spectrometry has been explored as a
technique for measuring trace levels of nitrogen oxides under sub-atmospheric conditions. The
technique employs tunable radiation near 226 nm to perform the photofragmcntation and subsequent
photoionization of NO fragments generated in the probe region, and a miniature pair of electrodes for
nonselective (total) ion detection. Optimum signal-to-noise conditions were determined and the
results demonstrate the feasibility of nonselective detection of the NO* ions. Limits of detection are
1 ppbv, 22 ppbv, 5 ppbv and 220 ppbv for NO, N02, HNO, and CH,NO„ respectively.
INTRODUCTION
Current measurement methods for nitrogen oxide species consist of chemiluminescence
spectrometry, absorption spectrometry and a variety of filter and denuder collection techniques HJ.
For measurements requiring very high sensitivities (pptv), photofragmentation/iaser-indnced
fluorescence (PF/LIF) techniques have been developed that allow near real time monitoring of NO,
NO, and HN03 at pptv levels (2-4). Despite the analytical capabilities of the PF/UF approaches, the
techniques are considerably more complex than conventional approaches and are therefore impractical
for routine applications.
Since 1979, laser-induced ionization has been recognized as a potentially powerful method for
trace determinations of atmospheric species (5.6). However undesirable aspects of laser-induced
ionization measurements, including relatively high laser intensities and sometimes persistent
nonresonant background ionization signals, have inhibited the development of the method.
Photofragmcntation methods are especially effective for monitoring oxides of nitrogen since
most of the compounds share a common functionality, N02, which is readily removed by absorption
of ultraviolet radiation (A.<250 nm). Species that have been determined by photofragmentation
approaches include HNO, (by OH L1F) £21. NO, (by NO LIF) (4) and various nitroorganics (by NO
onization) (7-10). Previously we demonstrated that a photofragmentation/photoionization (PF/PI)
ipproach is feasible when the samples are present in a molecular beam and a time-of-flight mass
spectrometer is used for ion detection £7}. The selectivity of the PF/PI approach when using 226 nrn
adiation was evidenced by virtually exclusive ionization of NO relative to any other species. Tne
malytical selectivity was such that nonselective ion detection was proposed as a simplification to the
nethod.
In the current approach, nitric oxide (NO) is detected directly by a 1+1 resonance-enhanced
lultiphoton ionization (RE.VIPI) process via the AJ2+<-XJn transition at 226 nm. Other nitrogen
xides are detected using a photofragmentation/photoionization (PF/PI) approach where the laser is
irst used to fragment the parent molecule and then probe the resulting fragments. Nitrogen dioxide
W)2), nitric acid (UNO,) and other nitrocompounds all share the NO, functionality which is
fficiently fragmented at 226 nm. Following fragmentation, the NO, or N02' fragments absorb
lother photon at 226 nm and predissociate to produce NO, which is detected by the REMPI process
ascribed above. Due to the high efficiency of the individual fragmentation processes and the
lotoionization at 226 nm, the PF/PI approach can easily be accomplished with only modest pulse
931
-------
energies (on the order of |iD.
We have investigated the analytical utility of PF/PI detection of atmospheric nitrogen oxides
at near ambient conditions. Studies have been performed to determine the optimum conditions for
PF/PI measurements and to evaluate analytical figures of merit for NO, N02. HNO, and CH3N02.
Measurements have been performed up to atmospheric pressure employing total ion detection.
Results of tlie PF/PI studies are compared to similar PF/L1F approaches to illustrate the relative
merits of the methods.
EXPERIMENTAL
An excimcr-pumpcd dye laser system with frequency doubling (Lumonics, HYPER EX-400,
HYPER DYE-300 and HYPER TRAK-1000) was used to provide up to 100 nJ pulses at 226 nm.
The laser output was directed using prisms to the photolysis/ionization sampling cell. Focusing of
the laser was accomplished using a 250 mm lens external to the cell. The photolysis cell consisted
of a six arm stainless steel cross with arm diameters of 4 cm. Quartz windows mounted on the cell
provided optical access to the center of the cell where two planar electrodes served as ion/electron
detectors. The electrodes, laboratory constructed from stainless steel sheets, were each approximately
1.5 cm2 in area and were separated by 0.A3 cm. Electrical contact to the electrodes (used for biasing
and for signal collection) was accomplished through a plate mounted to one of the arms on the cell.
Collection voltages ranged from 0 to 800 V.
Samples were prepared by serial dilution of standard gases (NO. NO, in air or N2) or were
sampled as trace species at their room temperature vapor pressures (HNO„ CHjNOs) in buffer gases
(air, N2). Samples were flowed through the photolysis cell to prevent build-up of photolysis
products. Sample flows were nominally 500 cc/min. The photolysis cell volume was estimated to be
350 cc.
Signals from the detection electrodes were amplified using a current amplifier (Keithley 427,
gain 10® V/A, time constant 0.01 ms) and then sampled by a boxcar averager. The signals were also
viewed in real-time on a digital oscilloscope. The output of the boxcar was acquired by a personal
computer for storage and subsequent data analysis. Analytical sensitivity determinations were
performed using a boxcar gate of 15 us with 100 shot averaging at 10 Hz laser repetition rate.
RESULTS
In previous studies of the PF/PI approach at low pressure, selective ionization of the NO
fragment was observed at 226 nm for a wide variety of compounds (2). The high selectivity
observed in that study suggested extension of the PF/PI method to higher pressures with nonselective
ion detection, since mass selective detection was apparently unnecessary at reduced pressures. In the
present studies, fragment ionization spectra were recorded at near atmospheric pressure conditions
with nonselective ion detection. The excitation spectra for NO and NO, exhibit numerous rotational
lines belonging to the A2£"<-XJn band of NO. Ionization spectra for NO generated from HN03 and
CH3N02 also show similar features confirming the production of NO fragments. It is noteworthy thai
there is sufficient spectral resolution to distinguish individual rotational lines of NO, which is an
important criterion for the PF/PI technique to be useful at near atmospheric pressures. As there is no
ma.ss selectivity in the ion detection step, the selectivity of the method depends directly on optical
selectivity provided by the laser. The current results indicate that the use of low laser pulse energies
enables sensitive and selective detection of ambient nitrogen oxides with a minimum of nonresonant
background ionization signals at 226 nm.
To determine the optimum experimental conditions for the PF/PI technique as applied to
ambient measurements, parametric studies of the signal-to-noise ratio (SNR) as functions of the
measurement cell pressure and voltage were performed. A plot of the SNR as a function of the
measurement cell pressure shows a maximum in the near 100 torr indicating an optimum pressure
932
-------
region for analytical measurements. Over the pressure range studied (10-760 torr, constant mixing
ratio), the measured noise is relatively stable and the SNR is dominated by changes in the signal
magnitude. At higher pressures, the signa! is suppressed by quenching. At lower pressures, the
observed signals are reduced by sample dilution.
A similar study of the SNR as a function of the detection electrode voltage was performed.
Plots of the data for NO and NO, (at a constant mixing ratio) are characterized by a saturation curve
which indicates that the SNR reaches a maximum value above 400 V. The saturation behavior
suggests that at 400 V the electrode voltage is sufficient to collect all available ions/electrons
produced within the electrode spacing before they are lost to attachment and/or recombination
processes (5). It is worth noting that the optimum conditions determined in the present study are
characteristic of the experimental parameters employed and it is therefore likely that different
optimum conditions will he realized fnr different electrode spacings, different focal characteristics of
the laser, etc.
In previous studies of the PF/PI approach applied at low pressure, limits of detection (LODs)
ranged from 8 ppbv for NO and 240 ppbv for NO, to ppmv for larger nitroaromatics ill. In the
present study, LODs of 1 ppbv for NO, 22 ppbv for NO,, 5 ppbv for HNO, and 220 ppbv for
CH,N02 (signal-to-noise of 3) have been obtained at the optimized experimental conditions (100 torr
and 400 V). From the results of the current study, there appears to be an order of magnitude
improvement in the LODs over the low pressure results Q), although improvements in sensitivity
should be weighed against potential losses in selectivity. Alternatively, the simplicity of nonselective
ion detection and freedom from high vacuum apparatus are also important advantages in favor of the
current PF/PI technique.
It is worthwhile to compare the results of the current study with those obtained using similar
PF/LIF approaches. The best LODs (signal-to-noise of 3) reported for NO, NO,, HNO, and CH,NO,
using PF/LIF techniques are 5 pptv QL 15 pptv (4]. 30 pptv <21 and 2 ppbv fl I), respectively. Both
and two-color excitation PF/LIF approaches have been employed with emphasis placed on the two-
color approaches for NO and N02 in recent years (3.4). For NO and N02, it has been observed that
the one-color excitation PF/LIF is approximately one order of magnitude less sensitive than the two-
color approach, primarily due to the "white" fluorescence background which is a limiting noise in the
one-color approach. For comparison, the PF/PI technique (as employed in the current studies)
employs a single laser as both the photolysis and ionization source and is not susceptible to laser
scatter and/or "white" fluorescence noises.
A direct comparison of the results of this study employing PF/PI with those employing LIF
indicates that the two methods are similar in performance. In the case of NO, the most appropriate
Comparison of the PF/PI and LIF methods is with the one-color LIF measurements of NO at 226 nin,
as the PF/PI technique only uses a single laser source. The LOD for NO is 1 ppbv for PF/PI (10 sec
integration) and 50 pptv for one-color LIF (1 min integration) 112). These sensitivities (LODs) are
nearly within an order of magnitude and are likely to be even closer for similar integration times. In
the case of NO?, the PF/LIF result is approximately 3 orders of magnitude lower than the PF/PI
result, however, the PF/LIF measurement makes use of three lasers, one as a laser photolytic
converter and two for the two-color excited LIF measurement.
Tropospheric nitric acid levels have been measured using an ArF excited PL/LIF approach
'_2j. Papenbrock and Stuhl have reported an LOD of 30 pptv which compares with 5 ppbv observed
ising ihc PF/PI approach. It should be noted, however, that the ultimate sensitivity of the PF/LIF
ncthud was evaluated using an integration period of 1 hour (compared to 10 s for PF/PI), which
mplies that similar integration periods would lead to more similar sensitivities.
As the PF/PI sensitivity for HNO, is higher relative to that of N02, it is of interest to
peculate on the fragmentation/ionization mechanism for HNO, at 226 nm. If it is assumed that the
iroduction of NO from HNO, occurs exclusively by way of N02 fragmentation followed by N02
redissociation, the sensitivity for HNO, should not be higher than for NO,. As the sensitivity is in
ict higher, this suggests that another PF/PI mechanism is operative for this compound. In recent
-------
studies of the 193 nm photolysis of UNO,, Kenner et al. have determined that the production of
OH(A) fragments proceeds by way of an intermediate species rather than direct photolysis £13}.
Based on energy and spin conservation requirements, they have concluded that the intermediate is
triplet HONO.
From studies of the photodissociation of HN03 at 248 nm, Schiffman and coworkers have
suggested two possible mechanisms by which HNO, is fragmented to produce NO, one of which
produces NO directly from the parent, the other through the HONO intermediate (14). They contend
that both of these pathways are possible at wavelengths less than 250 nm. These proposed
mechanisms suggest that the high sensitivity of UNO, may be due to the direct phntolytic production
of NO or the production and subsequent photolysis of the IIONO intermediate rather than N02. The
different PF/PI sensitivities for HNO, and N02 can therefore be rationalized by different rovibrational
distributions of NO(X) resulting from the photolysis of HNO, or HONO versus the predissociation of
NOj at 226 nm, respectively.
The PF/PI technique has been demonstrated in this study using a variety of odd nitrogen
compounds including NO, NO,, HNO, and CH,N02. Although it is obviously well suited to
measuring NOx (NO + NO,), it may also be a potentially effective way to measure total odd nitrogen,
NO,. Current methods for measuring NO„ emphasize the use of standard chemiluminescencc
technology in combination with catalytic reduction of odd nitrogen to NO using Au or Mo catalysts.
The techniques are sensitive but can suffer significant interferences from non-odd nitrogen
compounds leading to erroneously high measurements (1.15). The PF/PI technique is highly selective
and will not suffer interferences from those same compounds.
One of the most abundant atmospheric nitrogen oxide compounds is N20 and it was of
interest as to whether it could be detected using the PF/PI approach. As the troposphcrie levels of
N20 are generally higher than N0„, sensitivity to this compound would represent a significant
interference for determinations of odd nitrogen compounds. Although fairly high concentrations of
N20 were sampled (>500 ppmv), no detectable NO* ion signals were observed. Based on the known
spectroscopy of N20 in this wavelength region, it is not surprising that ion signals were not observed.
According to Herzherg (16). and Sponer and Bonner (17). absorption in this region is dominated by
predissociation of the molecule to N2 and O. Lack of sensitivity to this compound at high
concentrations indicates that N20 will not interfere with PF/PI measurements of NOx and/or NO, at
typical tropospheric levels.
The PF/PI method possesses important analytical features that are well-suited to atmospheric
monitoring applications. The present technique is sensitive, as evidenced by the low ppbv LODs
demonstrated By virtue of the low laser pulse energies employed and the high spectral resolution of
the dye laser output, the technique possesses excellent selectivity for NO, NO, and N02
functionalities with minimal nonresonant background ionizations. Furthermore, by using a single
laser tuned to 226 nm and a simple photolysis cell with total ion collection, the PF/PI apparatus is
easily implemented since it does not require multiple lasers or stringent geometric considerations
which arc necessary when optical detection approaches are used (e.g. LIF). By employing a 10 sec-
integration time, the PF/PI technique is able to detect low ppbv levels in virtual real-time and thus is
competitive with other conventional methods used for NOx monitoring applications.
CONCLUSIONS
We have demonstrated a PF/PI approach used to determine trace levels of nitrogen oxide
compounds. The technique employs a laser operating at 226 nm that selectively excites and ionizes
NO molecules by a 1+1 REMPI process via the A2£*<-XJn band. The laser is simultaneously used
to fragment larger odd nitrogen species, which at 226 nm results in the production of NO
photofragments that can be detected by the same REMPI process. Thus, one laser can accomplish
simultaneous detection of NO, NO,, HN03 and other nitrogen oxide species. Presently the LODs
extend to the low ppbv for NO, N02 and HNO} with sub-ppbv LODs anticipated. The technique is
934
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well-suited to NOx determinations and has excellent potential for measuring NOy. Although the
technique is sensitive to a wide range of nitrogen oxides, it is insensitive to N20.
Acknowledgements: Support from the ARL/NRC Postdoctoral Research Associateship Program (JBS
and GWL), the Independent Laboratory Initiated Research (ILIR) Award (RCS) and the PIF/OSD
Capital Investment Program (RCS) is gratefully acknowledged.
References
]. J.E. Sickles; Gaseous Pollutants; J.O. Nriagu, Ed.; Wiley and Sons, New York, 1992, pp. 51-
128.
2. Th. Papcnbrock, F. Stuhl, K.P. MUller and J. Rudolph, J. Atmos. Chem. 15, 369-379, 1992.
3. J.D. Bradshaw, M.O. Rodgers, S.T. Sandholm, S.KeSheng and D.D. Davis, J. Geophvs. Res.
90 (D7), 12861-12X73, 1985.
4. S.T. Sandholm, J.D. Bradshaw, K.S. Dorris, M.O. Rodgers and D.D. Davis, J. Geophvs. Res.
95 (D7), 10155-10161, 1990.
5. J.H. Brophy and C.T. Rettner, Optics Letters 4, 337-339, 1979.
6. Assessment of Techniques for Measuring Tropospheric N^Ov, NASA Conference Publication
2292, 1983.
7. G.W. Lemire, J.B. Simconsson and R.C. Sausa, Analytical Chemistry 65, 529-533, 1993.
8. J.B. Simeonsson, G.W. Lemire and R.C. Sausa, to appear in Proceedings of the SPIH/AWMA
International Symposium on Optical Sensing for Environmental Monitoring, 1993.
9. J.B. Simeonsson, G.W. Lemire and R.C. Sausa, Analytical Chemistry. 1994 (in press).
10. A. Clark, R.M. Deas, C. Kosmidis, K.W.D. Ledingham, A. Marshall, J. Sander and R.P.
Singhal, to appear in Proceedings of Sensors 2: Technology, Systems and Applications, 1993.
11. J. Schendel, R. Hohmann and E.L. Wehry, Appl. Spectrosc. 41(4), 640-644, 1987.
12. J.D. Bradshaw, M.O. Rodgers and D.D. Davis, Applied Optics 21(14), 2493-2500, 1982.
.3. R.D. Kenner, F. Rohrer, Th. Papcnbrock and F. Stuhl, J. Phvs. Cliem. 90, 1294-1299, 1986.
4. A. Schiffman, D.D. Nelson, Jr., and D.J. Nesbitt, J. Chem. Phvs. 98, 6935, 1993.
5. D.W. Fahey, G. Hiibler, D.D. Parrish, E.J. Williams, R.B. Norton, B.A. Ridley, H.B. Singh,
S.C. Liu and F.C. Fehsenfeld, J. Geophvs. Res. 91 (D9), 9781-9793, 1986.
5. G. Herzberg; Electronic Spectra of Polyatomic Molecules; Van Nostrand Reinhold Company,
1966, pp. 505-507.
93 *
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H. Spoiler and L.G. Bonner, J. Chem. Phvs. 8, 33, 1939.
936
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Measurement of the Effects of Moisture Distribution
on the Transport Properties of Radon and Other
Soil Contaminants in EPA's Soil Chamber
by: Ronald B. Mosley
U.S. Environmental Protection Agency
Air and Energy Engineering Research Laboratory
Research Triangle Park, NC 27711
Richard Snoddy and
Samuel A. Brubaker, Jr.
Acurex Environmental Corp.
P.O. Box 13109
Research Triangle Park, NC 27709
ABSTRACT
Measurements of both diffusive and advective transport of SFt
used as a tracer in EPA's soil chamber are reported. These studies
involve measurements of the times-of-flight of a tracer gas along
different paths in the soil to determine the uniformity of the soil
and the moisture distribution. It is observed that values of
permeability computed from the measurement of total flow are not
consistent with permeabilities determined from the time-of-flight
measurements. The reason for this discrepancy is not understood.
INTRODUCTION
Significant health risks are associated with radon and other
soil-gas-borne contaminants that enter the indoor environment. In
an effort to develop better methods to reduce these risks, EPA is
studying the physical mechanisms by which soil gas contaminants
migrate through the soil and enter buildings. It is v/idely
accepted that advective flow is the dominant mechanism by which
radon and other soil gas contaminants enter buildings.
Consequently, it is important to understand how the properties of
soils influence these processes. The present measurements were
performed in EPA's soil chamber. While radon distribution in the
soil has been measured and reported in the past, the current
measurements use a tracer gas in order to look at specific
properties of the soil. Both diffusive and advective transport of
SF6 was studied to investigate the effects of moisture distribution
This paper has been reviewed in accordance with the U.S.
Environmental Protection Agency's peer and administrative review
policies and approved for presentation and publication.
937
-------
on the transport rates. SF6, used as a tracer, served as a
surrogate for a contaminant gas and was used to evaluate the degree
of uniformity of the transport properties of the soil. These
measurements are important because both the diffusion coefficient
and the permeability for gaseous migration in soils depend strongly
on the distribution of moisture in the soil.
EQUIPMENT AND EXPERIMENTAL DESIGN
The soil chamber has dimensions of 2 x 2 x 4 m, with 4 m being
the length. The chamber, described elsewhere, (1,2) was designed
to simulate an infinitely long cylindrical cavity buried 1 m below
the surface of the soil. The cylinder attempts to simulate the
infinite geometry by using guard ends to isolate the measurements
in the central region of the soil from the edge effects introduced
by the chamber walls at the ends of the cylinder. The finite
dimensions in the direction transverse to the axis of the cylinder
can be accounted for by imposing the appropriate boundary
conditions (3). Twenty-three recirculating probes for collecting
gas samples as well as for measuring temperature and pressure are
distributed in the central plane 2 m high and 4 m long. These
probes are arranged in rows at five different depths in the soil.
All the measurements and calculations discussed here relate to this
measurement plane. Four vertical moisture measurement tubes arc
offset from the measurement plane. A Troxler's Sentry 200-AP unit
is used to measure moisture over the entire depth of the soil. The
approach is to inject SFC into the probes, one at a time, and
measure the time required for it to be advectively transported to
the central collection tube. A fixed volume (about 10 cm3) of SFe
was injected into a probe followed by an injection of sufficient
air to flush the SFe from the probe. The arrival of the SF6 was
detected by a Miran Infrared detector. A Miran 203 Specific Vapor
Analyzer and sometimes an additional Miran 1A-CVF were used. The
time was determined by the arrival of the peak of the pulse. By
comparing the times-of-flight for symmetrically located points, the
uniformity of the transport properties of the soil can be judged.
These data will also test the validity of mathematical models (4).
ADVECTTVE FTjOW
A mathematical expression for the time-of-flight of an air
parcel along a flow streamline using the geometry of the soil
chamber was presented by Mosley (4):
where t is the tirae-of-flight along a streamline (min), n is the
dynamic viscosity of the soil gas (kg m 1 s"') , h is the depth of the
cylinder in the soil (m) , k is the soil permeability (m2) , Pe is the
applied pressure (Pa), b is the radius of the cylinder (m), and I
is the distance (in multiples of h) horizontally from the cylinder
1(25+ (£2-l) t-^+cos-1!
93 X
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to where the streamline intersects the surface of the soil. This
expression applies when the diffusion is negligible in comparison
to advective flow. The approach for the experiment is to inject a
puff of SF6 at numerous points within the measurement plane and
measure the time required for its arrival at the central collection
tube of the chamber. These measured times will be used to test the
validity of equation (1) . The intent was to flow at a sufficiently
high rate that the contributions from diffusion could be ignored.
These measurements were performed at 19 of the 2 3 probes. The
measured times are given in Table 1. Equation (1) consistently
ovcrpredicts the times-of-flight by a factor of 3 - 4 when using a
value of permeability that correctly predicts the total flow rate.
Since the absolute values of tines predicted by equation (1)
do not agree with the measurements, ratios of measured times are
compared for pairs of probes that are symmetrically located
relative to the collection tube. It is reasoned that air parcels
travelling from symmetrically located probes will traverse
comparable distances in soils with similar moisture contents.
Therefore, the times should be comparable. For a more quantitative
analysis, a very simple model is considered. If the probe were
considered a cylindrical source with small radius located in an
infinite uniform medium, the velocity resulting from an applied
pressure would be (5)
where v is the velocity (m s !) and r is the radius of the cylinder
(m) . The time-of-flight along a flow line would then be given by
integrating the reciprocal of the velocity
For the pairs described above, the ratios of the times vary like
the squares of the ratios of the distances. These ratios along
with their percent differences are shown in Table 2. The percent
differences are all within the expected errors of measurement.
This result suggests that the permeability and moisture
distribution are largely independent of horizontal position.
Suppose we now plot all the measured timer, as a function of the
square of the distance between the injection point and the
collection point. These results are shown in Fig. 1. While these
data are quite scattered, it can be seen that they tend to separate
into two groups. Probes at the bottom of the chamber where the
moisture is high tend to lie along a straight line near the upper
edge of the data, while much of the remaining data tend to lie on
a lover line with smaller slope. This result should not be
surprising since the permeability is known to vary with moisture
content. Fig. 2 shows an empirical fit of the sane data to a
kP.
<2)
2-|i
(3)
939
-------
product of distance squared and a power of the moisture content at
the injection probe. It was found that an exponent of 0.75
provided the best fit. The coefficient of determination, R3, is
0.98, indicating a relatively good fit. The regression slope
(1342.7) yields an estimate for the permeability of 9.62 x 10'11 m2.
This value of k is three times larger than was inferred (3.17 x
10'11 in2) by earlier measurements of total flow and also by
measurements with point permeability probes (1). In fact, if this
were the correct value of permeability, equation (1) would give a
much better prediction. The moisture dependence represented in
Fig. 3 could be interpreted as the reciprocal of an effective
permeability averaged over the migration path.
DIFFUSIVE FliCJW
The inability of equation (1) to predict the migration times,
naturally leads to the question of whether diffusion was really
negligible. After considering that diffusion might not be
negligible after all, diffusion measurements were performed for 14
of the previous 19 probes. These measurements were performed in a
manner similar to the advective measurements except no flow was
induced. A puff of SFs was injected into each probe, and the time
required to arrive at the central tube was measured. Once again
suppose that the probe represents a point source in a plane. The
solution for the diffusion problem is given by Crank (6) as
where A is a measure of the amount of gas injected, and D is the
moisture dependent diffusion coefficient. The Miran detector will
see the passing puff as a pulse with a peak. The time required for
the arrival of the peak can be computed by differentiating equation
(4), equating the derivative to zero, and solving for the time
corresponding to the maximum in the concentration curve. This
process yields
where t(ax represents the time at which the peak of the pulse
arrives at the collection tube (min). Motivated by a model by
Rogers and Nielson (7) for the dependence of diffusion coefficient
on soil moisture, Fig. 3 plots the diffusion times as a function of
rf exp(3s + 6s7) . The coefficient of determination, R2, for the
regression curve is (0.99). Since these data represent probes from
all regions of the measurement plane, they not only show good
agreement with the Rogers and Nielson model, but also suggest that
the soil and the moisture distribution within the soil are fairly
uniform in the horizontal direction. Using the slope (425.8) of
the regression curve in Fig. 3, the effective diffusion coefficient
is computed to be 9.1 x 10"G m2 s'1 near the surface of the soi] and
940
-------
4.48 x 10fi ra? s 1 near the lower row of probes. These values can
be compared with previously measured values of 1.2 x 10"6 and 8.8
x 10"B raz s"1 (8) .
DISCUSSION AND CONCLUSIONS
While the measurements of the diffusion rate of SFfi seem in
reasonable agreement with other measurements and with an accepted
model for its dependence on moisture, the time-of-flight
measurenents associated with advective flow seem to imply a larger
permeability (9.6 x 1CT11 hi2) than is required to describe the total
rate of flow (3.17 x 10"" m2) . The reason for this discrepancy is
not presently known. Diffusion taking three times as long as
advective flow might suggest that diffusion is negligible, but this
conclusion is not certain. It is possible that the time-of-flight
depends more sensitively on the shape of the streamlines than does
the integrated flow. Neither equation (1) nor equation (3)
accounts rigorously for the shape of the stream!ines for the
boundary conditions associated with the soil chamber. A rigorous
calculation in this case will require a numerical solution to both
the velocity and the integrated time.
REFERENCES
1. Mosley, R.B., Snoddy, R., and Brubaker, S.A.,Jr. Measurements
of soil permeability and pressure fields in EPA's soil-gas
chamber. Presented at the 1993 International Radon Conference,
Denver, CO, September 20-22, 1993.
2. Menetrez, M.Y., Mosley, R.B., Snoddy, R., Ratanaphruks, K. ,
and Brubaker, S.A., Jr. Evaluation of radon movement through
soil and foundation substructures. Presented at the 1993
International Symposium on Measurement of Toxic and Related
Air Pollutants, Durham, NC, May 4-7, 1993.
3. Mosley, R.B. An analytical solution to describe the
pressure/flow relationship in EPA's soil-gas chamber.
Presented at the 1993 International Symposium on Measurement
of Toxic and Related Air Pollutants, Durham, NC, May 4-7,
1993.
4. Mosley,R.B. A simple model for describing radon migration and
entry into houses. In: Cross, F.T., ed., Indoor Radon and Lung
Cancer: Reality or Myth?; Part 1, Battelle Press, Columbus,
OH, v. 1, pp. 337-356, 1992.
5. Hughes, W.F. and Brighton, J.A. Schauin's Outline of Theory and
Problems of Fluid Dynamics. McGraw-Hill Book Company, New
York, NY, 1967.
6. Crank, J. The Mathematics of Diffusion, Oxford University
Press, Ely House, London, 1975.
7. Rogers, V.C. and Nielson, K.K. Correlation of Florida soil-gas
permeabilities with grain size, moisture, and porosity. EPA-
600/8-91-039 (NTIS PB91-211904), June 1991.
8. Nazaroff, W.W, Lewis, S.R., Doyle, S.K., Moed, B.A., and Nero,
A.V. Experiments on pollutant transport from soil into
residential basements by pressure-driven airflow. Environ.
Sci. Technol. v. 21, no. 5, pp. 459 - 465, 1987.
941
-------
Table 1
Probe
*
Time measurements for
diffusion and convection.
Radial Diff
distance time
Convec
time
(m)
(m)
(m)
(min)
(min)
1
-1.543
0.435
1.621
1321
541.5
2
-0.511
0.435
0.713
a
a
3
-1.031
0.935
1.031
750
256.5
4
-1.543
1.462
1.631
2611
1468
5
-0.511
1.463
0.735
a
a
6
-0.264
0.277
0.367
173
46
7
-0.257
0.935
0.257
a
23
8
0.007
0.435
0.498
279
78
9
0. 260
0.935
0.260
a
26
10
0.262
0.677
0.366
169
45
11
0.513
0.435
0.713
a
a
12
-0.251
1. 182
0.353
183
54
13
0.013
1.562
0.629
576
376.5
14
0.261
1. 191
0. 367
210
56
15
0.518
1.465
0.743
a
a
16
0.999
0.945
0.999
752
261
17
1. 2 59
0.400
1.356
905
406
18
1.763
0.695
1. 779
2050
730
19
1.761
0.435
1.830
a
699. 5
20
1.284
1.462
1.368
2438
1107
21
1.769
1.462
1.847
a
1656
22
1.770
1.207
1.791
a
1009
23
1. 764
0.900
1.764
2100
7 64
Measurements were not performed.
Table 2
Probe
Comparison of ratios of time
and distance squared for
symmetrically located pairs
of probes.
i
j
(ti/t,)
(Ci/r,)'
% diff
1
17
1.334
1.429
7
1
19
0.774
0.784
1
6
10
1.011
1.005
0.6
7
9
0.868
0.971
11
12
14
0.9732
0.9257
5
4
20
1.326
1.422
7
4
21
0.882
0.7799
12
1800-1
c
c
1600-
tr
1400-
O
c.
1200-
c
1000-
800-
>
ft
600-
¥
400-
200-
<
0-
r m )
Fig. 1 Plot of time vs distance squared.
2 Plot of time vsthe product of distance
squared and moisture to 0.75 power.
^ 3000
I 2500
- 1500-
2 1000-
r ' exp(3s + 6s 7) (m 2)
Fig. 3 Plot of time vsthe product of diaancf
squared and the exponential factor i
the Roger's model.
942
-------
Comparison of Soil Permeability Measurements Using
Probes of Different Sizes and Geometries
by: Ronald B. Mosley
U.S. Environmental Protection Agency
Air and Energy Engineering Research Laboratory
Research Triangle Park, NC 27711
Richard Snoddy and
Samuel A. Brubaker, Jr.
Acurex Environmental Corp.
P.O. Box 13109
Research Triangle Park, NC 27709
Joseph Brown
Dept.of Civil Engineering
North Carolina A&T State University
1601 E. Market Street
Greensboro, NC 27411
ABSTRACT
The traditional method of measuring soil permeability to air
movement uses localized probes of varying size and geometry to
collect and measure the total flow passing through the probe over
a range of applied pressures. The permeability is typically
extracted from the measured flow/pressure relationship using a
derived solution to an idealized geometry that frequently does not
match the reality of the probe. This study compares side-by-side
measurements of soil permeability for a number of probes with
different geometries and relative sizes. A comparison of results
is discussed in terms of appropriate shape factors based on
geometrical differences. Attention is focused on the limit in
which the traditional approximations for short cylindrical probes
break down. It is suggested that the product of length and shape
factor in expressing flow for a very short cylindrical probe is
better approximated by an equivalent sphere with nearly equal
surface area.
INTRODUCTION
In order to measure the permeability of soil to air flow, it
is necessary to insert soma type of instrumentation into the soil.
Most in situ measurements involve inserting some type of
cylindrical tube with gas entry orifices into the soil and
measuring the rate of gas flow resulting from a given applied
pressure. Probes vary from tubes with an open end to closed tubes
This paper has been reviewed in accordance with the U.S
Environmental Protection Agency's peer and administrative review
policies and approved for presentation and publication.
943
-------
with a short section having numerous holes in the side for gas
entry. While both cylindrical and spherical geometries have been
used to represent the conditions for these measurements, few
details have been published on the assumptions used or the analyses
perfoi-med to evaluate these measurements. Researchers at Lawrence
Berkeley Laboratory (LBI,) (1-3) have provided some details about
the analysis of their probes. KPA's soil chamber contains 23 small
cylindrical probes made of fritted brass. While these probes were
designed primarily for collecting samples of soil gas for measuring
radon concentration, tracer gas concentration, or other soil
contaminants, they will also be used for local permeability
measurements. The need to develop geometrical shape factors for
analyzing the data from these probes prompted the current studies.
DEVELOPMENT OF EQUATIONS
Probes used for measurements can be simulated by the
idealization of a simple geometry for which mathematical solutions
are obtained. We will discuss cases of both cylinders and spheres.
First consider a cylinder buried in a semi-infinite block of soil
with a specified pressure difference relative to the air at the
soil surface. The approach will be to express the pressure/flow
relationship in terms of a geometrical shape factor that can be
computed from mathematical solutions for advective flow in a porous
medium. This relationship for cylinders can be expressed as
where Q is the flow rate (in3 s ') , Sc is the geometrical shape factor
(dimensionless} , L is the length of the cylinder (m) , k is the soil
permeability to air flow (m2) , |ji is the dynamic viscosity of the
soil gas (kg m"1 s1), and Ap is the applied pressure (Pa). An
expression for Sc, obtained from Hahne and Grigull (4), is given by
where r is the cylinder radius (m) , and h is the depth of the
cylinder below the surface of the soil (m). This approximation is
valid when h z. 2.5r and L >> r. While these conditions are easily
met, the standard probes used for in situ permeability measurements
frequently violate the second condition. The length of the
perforated section is usually not large compared to the probe
radius. It is readily seen that equation (2) becomes invalid as L
approaches r (the sign becomes negative). The short probes in the
soil chamber approach this limit and consequently gives rise to the
present concern relating to short probes. Because equation (2)
does not apply in the limit of short cylindrical probes, it is
Q = S^ L— AP
" V-
(1)
(2)
944
-------
be!ieved that the short probes can be better approximated by
appropriately chosen equivalent spheres. Spheres have been chosen
as an alternative representation for short cylinders because
mathematical solutions are available for spheres buried in a semi-
infinite medium (1), and because of the similarity between
equations (1) and (3) .
The relationship for spherical geometry is given by
(3)
where Ss is the shape factor for spherical geometry
(dimensionless), and r is the radius of the sphere (m). The shape
factor is given by (1)
1 -r/h'
A comparison of equations (1) and (3) indicates that the two
geometries would be equivalent if LSC = rS5. Intuitively, one would
expect this condition to apply most readily when the surface areas
of the sphere and cylinder are nearly equal.
MEASUREMENTS
In order to investigate the influence of the shape factor of
the probe on measured permeability, a number of spherical and
cylindrical probes of various sizes have been studied. The
dimensions of the cylinders are listed in Table 1, while the
dimensions of the spheres are given in Table 2. These studies were
performed by placing the probes in soil contained in a large
barrel. The permeability of the soil was varied by adding water to
the soil. The moisture profile in the soil was measured using a
Troxler Sentry 200-AP soil moisture monitor. While the expressions
for the shape factors given above do not apply rigorously for these
studies because of the finite volume of soil, they are reasonable
approximations and provide good relative comparisons of the
different geometries. It is the relative comparison that is
stressed in this presentation.
Each probe was constructed to have a highly porous surface to
ensure no significant pressure drop associated with penetration
through the surface of the probe. The spherical probes were
constructed from wire mesh, while some cylinders were made of wire
mesh and some were constructed from commercial well points. To
eliminate uncertainty introduced by pressure drop in the flow
lines, two lines were installed in each probe: one was used to
measure the flow, while the other was used to measure the static
pressure in the probe. The roles of these two lines were inter-
changed to confirm that there was no difference in the results.
945
-------
Measurements of pressure and flow rate are illustrated for
four cylinders in Fig. 1. Similar curves for four spheres are
shown in Fig. 2. As indicated in equations (1) and (3), the slopes
of the regression curves in these two figures contain both the
permeability of the soil and the geometrical shape factor. The
slopes of the regression curves of Figs. 1 and 2 are shown in
Table 1. The slopes of the regression curves in Fig. 2,
corresponding to spheres, are plotted as a function of (rS) _1 in
Fig. 3. A similar plot for the curves in Fig.l, corresponding to
cylinders, are shown in Fig. 4. According to equations (1) and
(3), these data could be combined to give a single composite curve
which is shown without the outlier data in Fig. 5. The slopes of
the regression curves in Fig. 5 yield values for permeability of
3.70 x 10 11 and 2.76 x lO"'1 m2, corresponding to the dry and wet
conditions, respectively. To determine the reasonableness of this
apparent change in permeability, we first consider the manner in
which the moisture was added to the soil. The first set of
measurements was performed after the soil had been packed dry with
no compaction other than hand patting. The soil was then flooded
with water from the bottom of the barrel until it was fully
saturated. The water was then allowed to drain out the bottom of
the barrel. Previous observations with this soil indicate that the
density increases by at least 10% through this process. The
porosity can be assumed to decrease by about the same amount. In
addition to having decreased porosity, the soil also retains a
significant amount of water that fills additional pores, resulting
in further reduction of the permeability. A quantitative estimate
of the change in permeability can be obtained from a model due to
Rogers and Nielson (5). According to this model, the ratio of soil
permeabilities in the two different states would be
Tr r (~12 t/V-m/J) (5)
2
-------
very close together. As can be seen from Table 1, C5 computed frosi
equation (1) would lie on the negative horizontal axis and both
values for C6 would have been significantly above the upper curve.
Using the idea of an equivalent sphere clearly gives a much better
representation for these short cylinders.
CONCLUSIONS
Since equation (2) is an approximation, it clearly breaks down
when the cylinder becomes sufficiently short. This has been
demonstrated in the cases of cylinders C5 and C6. It was shown
that an adequate substitute for the shape factor can bo developed
using an equivalent sphere of comparable surface area. A more
rigorous relationship between the surface areas of equivalent
cylinders and spheres could be developed on an empirical basis.
REFERENCES
1. Nazaroff, w.w. and Sextro, R.G. Techniques for measuring the
indoor s Rn source potential of soil. Environ. Sci. Techno],
V. 23: p. 451 - 458, 1989.
2. Garbesi, K., Sextro, R.G., and Nazaroff, W.W. A dynamic
pressure technique for estimating permeability and anisotropy
of soil to air flow over a scale of several meters, Lawrence
Berkeley Laboratory: Berkeley, CA, LBL-32723. 1992.
3. Fisk, W.J., Modera, M.P., Sextro, R.G., et al. Radon entry
into basements: approach, experimental structures, and
instrumentation of the snail Structures Project, Lawrence
Berkeley Laboratory: Berkeley, CA, LBL-31864. 1992.
4. Hahne, E. and Grigull, U. Forrofaktor und formwiderstand der
stationaren mehrdimensionalen warmeleitung. J. Heat Mass
Transfer, 18, 751 -767, 1975.
5. Rogers, V.C. and Nielson, K.K. correlation of Florida soil-
gas permeabilities with grain size, moisture, and porosity.
EPA-600/8-91-039 (NTIS: PB91-211904), June 1991.
Table 1. Characteristics of cylindrical probes
ID
CYLINDERS
L/r
(LS)'
DRY
/ A P'
)(10b
(m)
(m)
(m •)
(Pa m 3
CI
0.0166
0.330
19.8
1.16
7.31
C2
0.0117
0.254
21 .7
1.66
10.4
C3
0.0166
0.0508
3.05
3.20
22.4
C4
0.0117
0.0556
4 .76
4. 18
23.5
C5
0.0442
0.0476
1.08
-0.117
13.4
C6
0.0348
0.0584
1.68
1.32
13 .4
WET
. AP-
0
>(10'-'
(Pa m ¦' s)
9.49
13.4
30
32
17
17
947
-------
Table 2. Characteri6fci.es of spherical
probes
SPHERES
DRY
WET
ID
r
(rS) 1
{---)(1.0s)
<**)
(m)
(m 1)
(Pa m'3 s)
(Pa m"
SI
0.0372
1.84
11.4
15.1
S2
0.0299
2.36
13.9
18.4
S3
0.0211
3 .48
15.6
20.2
S4
0.O187
3.98
21.0
26.6
S 30-
Flowrate(10'5m3s"')
Fig. 2 Pressure vsflow for spherical probes.
5 3
Flow rate (10 m s
. 1 Pressure vsflow for cylindrical
probes..
T i 1 1 i r
0 0.5 1 1 5 2 2.5 3 3.5 4
(Shape factorx radius)*1, m'
Fig. 3 Plot of the regression slopesfrom
Fig. 2 vsthe reciprocal of rS.
35-
30-
wet
Q.
25-
3 15-
dry
o
1
3
2
4
5
(Shape factor x length) 1, m 1
Fig. 4 Plot of the regresaon do pes from
Fig. 1 vsthe reciprocal of LS.
i ' i i . ; i ;
0 0.5 1 1.5 2 2 5 3 3 5 4 4.J
(Shape factor x length) ~1, m
Fig. 5 Composite plot of the slopes from Fi
1 arid 2 vsthe reciprocal of LS oriS.
948
-------
Test Methods for Evaluating Reformulated Fuels
Michael C. Crnudace
PetroSpec, Inc.
60 Wells Avenue
Newton, MA (12159
The U.S. Environmental Proteclion Agency (EPA) introduced regulations in the
1989 Clean Air Act Amendment governing the reformulation of gasoline and dicsel
fuels lo improve air quality. These statutes drove the need for a fast and accurate
method for analyzing product composition, especially aromatic and oxygenate content.
The current method, gas chromatography, is slow, expensive, non portable, and
requires a trained chemist to perform the analysis. The new mid-infrared spectroscopic
method uses light to identify and quantify the different components in fuels.
Each individual fuel component absorbs a specific wavelength of light depending on
the molecule's unique chemical structure. The quantity of light absorbed is
proportional to the concentration of that fuel component in the mixture. The
mid-infrared instrument has significant advantages; it is easy to use, rugged, portable,
fully automated and cost effective. It can be used to measure multiple oxygenate or
aromatic components in unknown fuel mixtures. Regulatory agencies have begun using
this method in field compliance testing; petroleum refiners and marketers use it to
monitor compliance, product quality and blending accuracy.
949
-------
Peculiarity of Toxic Metals Emission Measurements
at Wastewater Treatment Plants
Vladimir Kogan and i'.dward Torres
County Sanitation Districts of Orange County. California (CSDOC)
108-14 Ellis Ave.
Fountain Valley. CA 92728-8127
Toxic metals emission can have a profound effect on the results of a facility's
health risk assessment, because of the extremely high unit cancer risks or hazard index
values of many metals.
The testing of metals emission at Publicly Owned Treatment Works (POTWs)
offer significant challenges due to the specifics of emissions from wastewater
treatment processes. Among these specifics are low concentrations of compounds of
interest, high air flow rates, and the fact that most of the metals considered
as toxics may be present in the plant's influent wastewater. It often makes the results
of the testing very difficult for proper evaluation.
CSDOC conducted extensive air- and liquid-phase source testing to characterize
toxic metals emission from the treatment processes at our two large wastewater
treatment plants. The presented paper describes the methods of sampling used, results
of the testing and their affect on the facilities' health risk assessments. A significant
part of the paper is devoted to a discussion concerning the sources of uncertainties in
testing results, including the effect of metals concentration in ambient air. Methods for
the handling and evaluation of results below the detection limit is also discussed.
950
-------
An Assessment of I^ow Emission Sewer Systems for Industry
Reese H, Howie, Charles J. Ztikar, and Parag Hiria
Alpha-Gamma Technologies. Inc.
900 Ridgefield
Raleigh, NC 27609
The U.S. EPA is currently developing air emission standards to control (he
emissions of hazardous air pollutants (HAI's) from industrial wastewater sources.
These new emission standards will require maximum achievable control technology
(MACT) which represents the most stringent level of control that is practically
achieved. A variety of emission control techniques are capable of meeting MACT
criteria, therefore, these standards provide some flexibility in selecting a strategy to
reduce HAP emissions froin wastewater sources.
Emission control techniques that allow facilities to maximize the use of
existing capital equipment in sewer and prctrcatment systems may offer a more cost
effective approach in complying with MACT standards. Water seals and covers can be
installed on existing sewer and prctrcatment systems and are capable of achieving
MACT emission control standards. The purpose of (his assessment was to;
1) identify emission suppression techniques that minimize the release of
volatile organic HAI's and other organic pollutants from industrial sewers and
prctrcatment systems;
2) characterize the applicability, design criteria, and technical issues
associated with the use of each suppression technique identified; and
3) relate the significance of these emission suppression techniques to
current and future federal air emission standards for wastewater sources.
The assessment indicated that industrial facilities ate currently using a variety
of techniques for minimizing emissions from sewer and pretrealment systems. In
addition, safety concerns have been expressed with the use of emission suppression
techniques. Some techniques allow volatile organic emissions to accumulate within an
enclosed space and create potential fire or explosion hazards. These hazards are
minimized when current safety practices and safeguards are implemented and
maintained.
Common .suppression techniques applied to sewer systems include: installing
above ground hard pipe sewers; installing water seals on process drains and sewer
ventilation pipes; creating surcharged sewer lines; and creating negative pressure sewer
951
-------
lines. Aji inci easing trend of using above ground hard pipe sewers at facilities
was noted. This technique is favored because it allows the development of an
inlegiated cnviiuiiwentul strategy to comply with multimedia standards.
Common suppression techniques applied to pretreatment systems include: using
purge gases for fixed roof structures; installing floating tool's for storage tanks and
oil-water separators; and installing floating membranes for large surface
impoundments. No trends of favoring the use of any one emission suppression
technique were observed for pretreatment systems.
Based on this assessment, sufficient information on individual control
techniques is available. However, little guidance is available for selecting and applying
alternative emission control techniques to reduce air emissions from an entire sewer
and pretreatment system.
-------
An Odor Control Study at Bissell Point Wastewater Treatment Plant
Jon F. Bergenthal Robert T. Jorgen John R. Gibbons
Sverdrup Civil, Inc.
13723 Riverport Dr.
Maryland Heights, MO 63043
ABSTRACT
The Metropolitan St. Louis Sewer District's Bissell Point Treatment Plant has been in operation since
1970. Odor complaints from the vicinity of the plant have occurred yearly, primarily from June to
September. The purpose of this study was to identify the sources of odors, determine the odor-causing
constituents and their emission rates, and recommend a phased plan that leads to the abatement of
objectionable odors from the Bissell Point Treatment Plant. Fn addition, the recommended plan addresses
Missouri Department of Natural Resource's (MoDNR) rules relating to odor emission, U.S. EPA's
pending Hazardous Air Pollutant standards, and MoDXR's pending plan on achieving VOC reductions
mandated by the Clean Air Act Amendments of 1990.
INTRODUCTION'
The Metropolitan St. Louis Sewer District's Bissell Point Treatment Plant currently receives an
average of 1H mgd of wastewater from a 57,000 acre service area covering the northern and eastern
parts of the City of St. Louis, and portions of North St. Louis County. Over half of the treatment plant's
influent BOD5 and TSS loadings result from industrial sources.
The number of odor complaints has increased since the new secondary treatment facilities began
to be brought on-line in October 1992. Two significant odor episodes occurred on December 14, 1992
and February 4. 1993. resulting in over 100 odor complaints. These episodes were apparently related
to the operation of the new trickling filters.
The Bissell Point Treatment Plant is a secondary treatment facility located adjacent to the
Mississippi River on East Grand Avenue. Land use around the facility is primarily industrial and
Dommercial. The closest residential areas are located 0.3 miles west of the treatment plant's fence line.
Wastewater and residuals treatment at the Bissell Point plant consists of the following operations:
nfluent Screening, Influent Pumping, Grit Removal. Comminution, Preaeration. Primary Settling,
1rimary Effluent Pumping, Trickling Filters, Aeration, Final Settling, Secondary Sludge Thickening.
Sludge Dewatering, Sludge Incineration, and Ash Handling.
>DOR AND VOC/HAP SOURCES AND EMISSION RATES
A variety of historical information relative to odor and VOC emissions at the Bissell Point
reatment Plant was researched including:
• Odor complaint records from 1983 to 1993
Qualitative odor sampling data from June 1982
• Gas and liquid-phase hydrogen sulfide (H?S) sampling data from Summer 1985
• Plant Influent VOC analysis from September 12, 1985
Liquid-phase H,S sampling data from 1990
• QUAD scrubber performance test data from Summer 1993
A file of odor complaint records spanning the years 1983 to 1993 was reviewed. All complaints
sre registered between the months of June and August, with the exception of the major odor episodes
l December 14, 1992 and February 4, 1993. In a few instances, descriptive information regarding the
lor was recorded; "septic", "sewage", "sour", and "burnt" smells were noted. Many of the complaints
sre from a residential neighborhood located southwest of the plant. During the December 14, 1992
isode, most complaints were from locations within 1 mile to the north and west of the plant.
953
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Sampling Plan and Methods
A summary of the sampling plan is presented in Table 1. Odor sampling was conducted on
September 15 and again on September 21,1993. These days were chosen for the dry weather conditions,
relatively warm wastewater and ambient air temperatures, and river stage low enough to have only a
minimal impact on the influent wastewater characteristics.
On each day, two samples were collected at each location (with four grab samples and one
24-hour composite of the treatment plant influent being the exception). At the preparatory and primary
treatment facilities, samples were collected between the hours of 8:00 a.m. and 10:30 a.m., and again
between the hours of 2:30 p.m. and 5:00 p.m. Samples at other locations were collected in late morning,
and again in the late afternoon or early evening hours.
Several different sampling techniques were used depending on the nature of the odor emission
source, and are described in the following paragraphs.
A ir Samp!es_fr o_m Building Spaces. Samples of air from building spaces, or die headspace
above water surfaces, were collected by use of an integrated sampler; see Figure 1. A vacuum pump
was used to pull u vacuum in the sampler, thereby causing the Tedlar® sample collection bag to expand
and fill with air drawn from the odor source through Teflon® tubing. The bag, thus conditioned, was
then deflated, and a second sample collected in the bag over a period of approximately 1 to 2 minutes.
1 he bag was then sealed and transported to the laboratory for analysis within a 24-hour period. Sulfur-
bearing compounds were identified through Gas Chromatography/Flame Photometric Detection (GC/FPD)
using modified CARB Mediod 16. Certain samples, as defined in the sampling plan, were also analyzed
by Gas Cliromatography/Mass Spectrometry (GC/'MS) to identify and quantify the 20 largest peaks, using
modified Kl'A Method TO-14. Ammonia was measured on site using Sensirlyne® tubes.
Air Samples from Liquid Surfaces. Samples from sources characterized as emissions from a
water surface were taken by use of a Sumnia® passivated AISI Type 304 stainless steel flux chamber:
see Figure 1. Compressed zero air was fed tlirough Teflon® tubing and swept through the flux chambei
at a measured rate for a period long enough to reach equilibrium. A sample of the off gas was thcr
collected in a Tedlar® bag via Teflon# tubing from the flux chamber. The bag, thus conditioned. wa!
then deflated, and a second sample collected in the bag. The bag was then sealed and transported to th<
laboratory for analysis within a 24-hour period, as defined above.
Wastewater Samples. Samples of influent and effluent wastewater streams were collected ii
40-ml glass vials with Teflon® caps, cooled to 4UC, and transported to the laboratory for analysis
I.iquid samples were analyzed for VOC/HAP purgeables by 1:PA Method 624.
Sampling Results
Ten (10) sulfur compounds and twenty-two (22) VOC/HAP compounds were detected :
significant levels; see Table 1. In addition to the specific VOCs listed, various higher molecular weigl
(9 to 12 carbon) branched alkunes and alkyl benzenes were identified in the emissions from varioi
treatment processes.
Ammonia never exceeded 0.3 ppm, and was most often at concentrations of less than 0.1 ppr
Ammonia does not appear to be a significant odor contributor at the Bissell Point plant.
A high concentration of carbonyl sulfide (COS) was detected in the incinerator stack gas. Tl:
compound has an odor similar U) hydrogen sulfide (rotten eggs) at concentrations above 1 ppm. ,
concentrations below 1 ppm, COS smells like "gunpow:der, fireworks, carbamate, and burnt rubber"1
Emission Rates
Table 2 contains the calculated emission rates for the morning and afternoon of September i
1993, Tabic 3 contains the same information but for the morning and afternoon of September 21, 19'.
The emission rates are listed by sampling locations (sources) and individual compounds. As the r
tables show, the first five compounds have the highest emission rates and contribute to odors at a vv
variety of sources. The most significant odor causing compounds appear to be hydrogen sulfi
dimethyl sulfide, and methyl niercaptan. Carbonyl sulfide appears to be a significant odor-caus
-------
compound primarily at the incinerator stack.
Non-sulfur odorous compounds, such as ammonia and various volatile organics (e.g., toluene,
acetone, methylene chloride), were detected in the off gas from various treatment units. However, these
compounds were detected at relatively iow concentrations.
At 10:30 a.m. on September 21, a hauled-in waste was received at the plant that contained large
quantities of dimethyl sulfoxide. Under certain conditions, the dimethyl sulfoxide degrades and forms
dimethyl sulfide. As the September 21 afternoon data shows, the dimethyl sulfide emission rate as
measured al the inlet to the QUAD scrubbers was 219,2 lb/day. Higher than normal releases of dimethyl
sulfide were also noted at the primary settling tanks and aeration tanks. It is likely that the severe odor
episodes of December 14, 1092 and February 4. 1993 resulted from similar releases of dimethyl sulfide
as a result of haulcd-in wastes.
Comparison of emission rates from various sources was achieved by normalizing the emission
rate data in terms of odor units per second. An odor unit is defined as 1 cubic meter of air at the
threshold concentration. Thus, a concentration of 1 odor unit per cubic meter is the level at which you
can just smell an odorous compound. To convert the mass emission rates (lb/day) for each odorous gas
to emission rates in odor units per second, the following conversion was made (Equation 1):
lh 1 m1 • X • y . 1 (I)
OdorUnir io6
To determine the number of pounds per odor unit, the following calculation was made (Equation 2):
OdorUnits lb day lb
— = • : : (2J
second day 86,400 see OdorUnil
vhere
X = Odor threshold of compound in ppm. v/v
Y Odorous gas density, ib/m3
he total emission rate in odor units per second (last column of Tables 2 and 3) for each source is the
jm of the individual emission rates for each odorous compound in odor units per second. Although this
ichmque may not account for the synergistic or antagonistic effects of combinations of odorous
impounds, it was considered to be conservative for this study.
aseline Odor Dispersion Modeling
Emission rates of odorous compounds were not sufficient by themselves to assess the significance
' the odor sources. The manner in which these emissions are dispersed between the sources and
:eptors must also be considered. For this study, a computerised odor dispersion model was used to
terniine how the odors from each source impact the community. This allowed each of the odor sources
be categorized as either a major, moderate, or minor odor source. In addition, the dispersion model
•ved as a basis for evaluating various odor control scenarios.
Isonleth Man for a Worst-Case Odor Emission Scenario. Figure 2 shows odor concentration
pleths for worst-case emission rates from a day when special waste was hauled in at the Bisscll Point
;atment Plant (with fence line) and the surrounding area. In this scenario, the entire receptor grid (3
es by 3 miles) is covered with an objectionable odor since the 1 odor unit/cubic meter isopleth is
'ond the boundary of the grid. To avoid obfuseation of the isopleth data as a result of cluttering, the
hast odor concentration shown on this map is 74 odor units/cubic meter. More isopleth maps are
rented later which reflect the results of implementing various control strategies that should bring the
it into compliance with applicable odor regulations.
-------
Ranking of the Odor Sources
To determine the relative contribution of each source to the total odor burden, a culpability
analysis was performed. Based on the results of this modeling, each odor source was ranked as either
"major" (contribution > 30%), "moderate" (10% < contribution < 30%), and "minor"
(contribution < 10%). The following odor source ranking was established:
Major Minor
•Primary Settling Tank Weirs •Influent Pump Station
•Trickling Filters *Grit Tanks (water surface)
•Grit Building
Moderate •Comminutor Building
•Grit Tank Weirs •Primary Settling Tanks
•Preacration Tanks • Trickling Filter Pump Station
•Sludge FMdg. Ventilation Air •Aeration Basins
•Incinerator Stack "Final Settling Tanks
•Ash Settling Basin "Sludge Wells Ventilation Air
•Thickener Building Ventilation Air
VOC/HAP Emissions
One of the objectives of this project was to assess the plant's status relative to Volatile Organii
Compound (VOC) and Hazardous Air Pollutant (HAP) emissions. A combination of modeling and ai
sampling was used to determine the VOC/HAP emission rates.
For estimating the emissions from wastewater treatment processes, the Bay Area Sewuge Toxic
Emissions (BASTB v3.0) model was used. BASTH is a genera) fate model, and estimates variou
pathway losses (e.g., volatilization, sorption, and biodegradation) for 26 VOCs. Sverdrup has extende
the applicability of BASTE by adding several more VOCs that were detected at Bissell Point The mod<
allows for analysis of complex treatment configurations including split flows, recycle streams, an
biological processes.
Table 4 is a summary of VOC/HAP emission rates. For each compound, the emissions estimate
by BASTF- for wastewater treatment processes are listed, along with the emissions measured from t}
sludge processing operations. The total of the wastewater and sludge emissions for each compound a
listed in the third column of numbers; the fourth column denotes those compounds that are classified
HAPs. The data indicate a total of 23.3 tons of volatile organics emitted per year, with the majority
emissions coming from the wastewater treatment processes, it should be noted that limited VOC/H/
air sampling data trom the wastewater treatment processes collected during this study indicate that t
BASTE model predictions are conservative.
EVALUATION OF ALTERNATIVE ODOR CONTROL SCENARIOS
The degree of control necessary is defined in the Missouri Department of Natural Resourc
(MoDNR) odor control regulation for the St. Louis Metropolitan Region (10CSR 10-5.160) wh
requires that2:
No person shall emit odorous matter that will cause an objectionable odor (in this study > 1 o
unit/cubic meter):
• on or adjacent to residential, recreational, institutional, retail sales, hotel or educational premises
• on or adjacent to industrial premises when air containing such odorous matter is diluted with
twenty or more volumes of odor-free air (for this study, the odor concentration at an adjacent
industrial site may therefore be 20 odor units/cubic meter); or
• on or adjacent to premises other than those described above when air containing such odorous mi
is diluted with four or more volumes of odor-free air (for this study, the odor concentration at t
sites may therefore be 4 odor units/cubic meter).
!n addition, the City of St. Louis (where the Bissell Point plant is located) has an odor coi
regulation that differs slightly from the MoDNR rule3. In the City regulation, the ! odor unit/cubic n
limit applies to property zoned as residential. The four-to-one dilution applies to commercially z>
956
-------
property, and a 19-to-l dilution applies lo premises zoned for industrial use. The City's regulation
defines an odor as objectionable if 50 percent or more of a panel of at least 5 persons can perceive the
odor in a properly diluted sample.
To meet the above regulatory requirements, alternative odor control scenarios were developed to
control the major and moderate odor sources identified in this study. Control of minor sources would
only be considered if the alternatives for control of odors from major and moderate sources were
insufficient to resolve the odor problem a', the plant. The odor control scenarios were then
evaluated/modeled to determine the decree of control necessary to bring the plant into compliance with
the odor regulations.
The baseline odor control scenario assumes current conditions, i.e., wastewater loadings and odor
emissions will remain at present levels, dimethyl sulfoxide hauled-in waste will no longer be fed
upstream of the primary settling tanks, trickling filters will be covered and ventilation air scrubbed, and
incinerator afterburner controls will be used.
In a stepwise fashion, each odor control option was modeled and the isopleth maps were
compared with the regulatory odor concentration requirements to determine compliance. Figure 3 shows
that with all currently planned controls in place, odor regulation compliance is achieved on the nearest
industrial site vvirh an odor concentration of less than 20 odor units per cubic meter, but at the nearest
residential, retail, and hotel .sites, odor concentrations are between 4 ami 7 odor units per cubic meter.
Thus, additional controls are necessary to comply with the odor regulations.
As determined in the odor source ranking, the primary tank weirs are the largest uncontrolled
odor source and contributor to off-site receptors. Using the estimated emission rate from the primary
weirs with controls, the dispersion model was run again, resulting in a odor concentration isopleth map
'Figure 4). With the addition of primary weir controls, the plant still produces odor concentrations
greater than 1 odor unit/cubic meter at the residential, hotel, gas station, and restaurant sites und thus,
idditional controls are necessary.
The remaining control options address the odor sources ranked as moderate sources. Figure 5
hows that the resulting odor concentrations at the restaurant, hotel, gas station, and residential receptors
re 1.0 odor unit/cubic meter with the addition of grit weir, preaeration, and sludge building controls,
i summary of the plant's compliance status with the odor regulations under various odor control
oenarios is presented in Table 5.
J2COMMENDED ODOR CONTROL PLAN
The following recommendations were selected for the first phase of odor control at the Bissell
>int I'reannent Plant:
• Implement controls at each of the two major odor sources identified in this study (trickling filters
and primary settling tank weirs)
• Implement partial controls at several of the moderate odor sources (grit tanks, preaeration tanks,
and incinerator stack), where such controls have small implementation costs,
• Develop and implement an effective hauled-in waste stiategy. especially for wastes containing
dimethyl sulfoxide.
• Continue good O & M practices by cleaning out-of-scrvicc tanks as soon as possible and
removing sludge and scum from the primary settling tanks on a regular basis.
lur Control at Major Odor Sources
Trickling Filters. The trickling filters were identified as the most significant odor source at the
ltment plant. At the present time, covers are being added that should allow for the containment and
lection of the majority of odors for treatment in the existing QUAD scrubbers. The odor
centrations in the feed to the scrubbers varies depending on season, weather conditions (dry or wet
tlher), and the nature of hauled-in waste being received at the plant on any particular day. Control
he sodium hypochlorite (NaOCl) feed to the scrubbers is being enhanced to handle a wide range of
rous trickling filter off-gas.
-------
Primary_.SettIingX'*J,J= 30%), moderate (10% < contribution to receptors > 30%), minor (contribution to receptors <
10%). Two major odor sources were identified: 1) primary settling tank weirs; and 2) trickling filter
Based on this ranking, several odor control scenarios were developed and evaluated. With tl
implementation of all controls, the model predicted that the plant would meet the odor regulation.
A phased odor control implementation plan was developed for the Bissell Point plant. With t
implementation of all odor control recommendations, VOC/'HAP emission reductions from the plant we
estimated to be 20%.
RF.FERENCKS
1. Polgar, L.G ; Duffee, R.A. "Odor Characteristics of Mixtures of Sulfur Compounds limit
from the Viscose Process1', at the 68th Annual Meeting of the Air Pollution Cont
Association, Boston. Massachusetts, paper £75-55.2, 13 pages.
2. MoDNR 10 CSR 10-5.160 Control of Odors in the Ambient Air.
3. St. I.ouis City Ordinance 59.270 Section 20 Control of Odors in the Ambient Air.
-------
Table 1. Sulfur and VOC'HAP compounds detected at the Bisseil Point Treatment Plant.
I>tected Su|lurjlom doun ds
hydrogen sulfide
Ciirbonyl sulfide
rnefhyl mereiipL-n
dimethyl sulfide
carton disulfide
dimethyl disulfide
thiophene
>-methyl Ihiophene
ir»ohij(yl inercaplijii
elhyl melhy) sulfide
Detected VOC7HAH Compounds
ncelone dichlorobenzenc methylene chloride
benzene ethnnol styrene
oirbon disulfide ethyl methyl benzene tetrachloroefhene
carbonyl sulfide ethylbenzcnc ietrahvdrofiiran
chlorobcnzcne isopropanol toluene
chloroform methyl ethyl ketone trichloroethanc
trichlorocthcne
trichioroffuoromcthane
tnmethylbenzene
m & p-xylcnes
o-xylenc
959
-------
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960
-------
Table 4, Bissell f'oint Treatment Plailt VOC*/l 1A11 emission rates.
Emission Rate, tons/vear
Wastewater
S'uc'kc
CoiiKioum?
Treatment
Treatment
Total
HAP
Acetone
c.:>3
0.45
M*
Benzene
0.J2
0.06
0.18
0.18
Carbon disulfide
0.63
0.14
0.77
0.77
Oirbonvl sulfide
0.00
2.18
2.18
2.1$
Ch.'orobenzcne
DOS
-0 01
IS 08
o.os
Chloroform
0.8!
<0 01
0 81
o.ai
DichJoroben/ene
0.15
0.0!
0.16
0.16
Dimeili>l -ilfide
<0.01
0.31
0.3!
Dimethyl disulfide
"-UUI
<0.01
1 mercaptari
<0.01
0.37
0.37
__
Methylene chloride
3.24
o.tn
3.27
3.27
Slyrene
0.0?
0.04
0.00
(J .Do
Tetraehloroethcne
0.44
0.03
0.47
0.47
Tctrahydrcfuran
0.03
0.00
0.0.i
Toluene
4.79
0.54
5.33
5.33
Trie iiloroetl nine
0.00
0,:>3
0.03
0.03
Vrichlnroethene
Oil
o.o:
0.1!
o.n
Trie h lo ro fl uc rem etfi a nc
0.00
0.02
0.02
Trimet.iylbenzcne
2.43
0.05
2,1 H
..
Xylenes
0.65
0.0S
0.73
0.73
1 o(al
IS SO
4.46
23.26
14.81
able 5. Compliance status with St. Louis City odor regulation.
Control Potions
Eliminate Special Waste
I7iukliii£ Filler C''overs
neinerntor Afterburners
'rirn;irv Weir Controls
»rit Weir Controls
'reaeration Controls
¦lurigc Bidg. Controls
=• in compliance with the current odor regulations for the St Louis Metropolitan Region
- out of compliance wi'Ji ehe current odor regulations for the St. I.ouis Metropolitan Region
dieted value is out of compliance, but because of the model';; margin of error, the actu.il value could be ii: cojnpiiar.ee
;dicted value ;> ir. compliance, bet uecause of die model's marp.n of error, the actual value could be out of compliance
Industrial
Yes
Yes
Yes
Yes
Yes
Receptor Type
Commercial
No
No
No'
Yes"
Y'cs"
Residential
No
No
No*
No'
Yes"
961
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Odor Control
Advantages
Disadvantages
Technology
Packed Bed
•
Handles variations in odor
• High chemical costs
Scrubber
concentrations well
• Maintenance of chemical feed
•
Moderately efficient at VOC
systems
removal
• Maintenance of bed (fouling}
•
Small size
• Maintenance of wale: distribution
system (plugging)
• Chemical carryover
• Higher AP (fan operating costs)
Mist-type Scrubber
•
Relatively small size
• Moderately high chemical costs
•
Low AP (fan operating costs)
• Less responsive to variations in
•
No bed maintenance
odor conceotra:ion
• Less efficient at VOC removal
• Chemical feed system maintenance
• Nozzle maintenar.ee
• Compressed air system
• Chemical carryover
Biofilter
•
Fairly responsive to changes in odor
• Periodic bed replacement
concentrations
• Moisture and pH control
•
High VOC removal
requirements
•
Minimal chemical feed costs
• Larger space requirements
•
Minimal chemical feed systems to
• Higher AP (far. operating costs)
maintain
• No containable process parameters
•
No chemical carryover
• Potential cold-weather performance
deterioration
Tabic 7. Effect of recommended odor controls on plant VQC emissions.
Source
Uncontrolled VOC
Hmis-iion Rate (fpv"*
C'oitUcV.cd VOC
Emission Rate (U)v}
Grit Tanks
2.53
I 61
Prcacration/Infiucnt Channe!
2.05
0.49
Piiinarv Sailing Tankt
1 16
0.6S
Trickling Filters
11 6R
'.2.55
Incinerators
3.C3
0.30
AH Others
2.80
2.93
Total
23 26
18.56
962
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Integrated Sampler
Flux Chamber
ure 1. Photograph of rhe Integrated Sampler and the FUik Chamber
-------
Ton L,~ I 3 i.i
«y.? >s'»? a*.?
r "K/;. "i --r^/W-OT
\ •.. i . j*'-!I 'iii • < J «
d)
from Or Ig In
B&2 I6&? \6i? ?D/i7
" ' '.'/A
:7,^«
j/-
i i f,' I—
X Dls teicfi ( n) * r o t C'
-2«TC -1936 -JOB -930 «ju oJ i«62
i^43C. .i9M -'<00 -5-3?>
'"jIS. 2P6?
r/.w-'TTT*
KSM_:
*fccsu
'VU -14-S3
56? ? iw«: isxi'
Figure 2 Bissell Point and vicinity odor bepfeth maps s) with special h£jlrd-in wa«tc: b) wiui »i;
currcaUy planned odor cor.uoh unpkmtntta, c) with ill currently p!aof.ed and primiry weir odor
controls; and d) with 311 currently planned ind recommended odor cocjtoIs impltme^tei.
964
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POSTER SESSION
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Intentionally Blank Page
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Air Pollution Monitoring
in the Republic of Latvia
by
I.Lyuiko, R.Dubrovskaya
Environment Pollution Observation Centre
Latvian Hydrometeorological Agency
I9,K.Valdemara street, LV-1010 Riga, Latvia
First investigations ot the air pollution in Latvia wore started by the
Hydrometcorological Agency in 1968 in Riga. The surveys and preliminary
results, information available on (he pollution sources, knowledge of
climatic and meteorological peculiarities of the Republic's regions
formed the basis for the foundation of a national air pollution observation
service in 1972.
Currently the system of observations covers 9 cities (20 posts) with
emissions of maximum concentrations from industrial sources and roads
{Fig. 1, 2, 3), as well as recreation zones.
The list of substances to be under observations is specified taking into
account the amount and composition of emissions into the atmosphere.
Simultaneously with the air samplings, meteorological variables (wind
direction and speed, humidity and temperature of the air, atmospheric
phenomena) arc measured at the posts.
The most wide-spread admixtures encompass solid substances, sulphur
dioxide, nitrogen dioxide, carbon oxide, phenol, formaldehyde, ammonia,
aromatic hydrocarbons, hydrogen chloride, hydrogen sulphide and metals
(zinc, cadmium lead, copper).
Samplings are made by aspiration of some volume of the air through an
absorber filled with liquid or solid absorbent, which collects a substance, or
through an aerosol filter, which traps particles the air contains. For the
laboratory analyses, physico-chemical methods are used:
photocolorimetry, atomic absorbtion, spectrophotometry, gas
chromatography. The annual data base averages about 70,000 units .
Key principles of observations made in the Republic are:
¦ regularity of observations
- complexity of observations
- unity of sampling and analysis methods.
The Latvian national service is in the opinion that the hydrometeorological
service is responsible for both, environmental pollution and
hydrometeorological obseivations thai provides for integrated monitoring.
The service has the only real systematic and standard observational network
in the Republic.
967
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This enables the observational network to serve the main targets in the air
pollution monitoring:
- assessment ot pollution levels;
- determination of the tendencies in the pollution level under the influence of
human activities and meteorological conditions;
- possibility to produce short-and long-term forecasts ot variations in the air
quality;
- possibility to warn concerned organizations of sudden changes in the air
pollution level;
- comparison of the air pollution levels over different regions of the
Republic.
The long-term compatible observational data series allowed to determine
characteristics of the air pollution to be taken into consideration in building
objects of national economy, general planning of towns and settlements to
minimize impact on the atmospheric air.
To get more information on the air pollution, to further investigations ot
regional pollution in order to support socio-economical sector in our
Republic, and to warn of the transfer of pollutants from accidental emissions,
episodical and tinder-plume surveys are carried out in addition to standard
observations.
The data of observations show, that formaldehyde , nitrogen dioxide , phenol
and ammonia highly contribute to the air pollution over the Republic's towns.
Notwithstanding a decreasing tendency recorded in the emissions . a
marked reduction has not been observed in the air pollution with particulated
matter, sulphur dioxide, carbon oxide and nitrogen dioxide.
To estimate the air pollution level, indirect methods are also run, including
precipitation chemical composition and snow pollutant content
determinations.
Precipitation chemical composition is analyzed to measure contributions of
local emitting sources and admixtures transfer with the air masses.
In 1989 precipitation quality monitoring network was established in the
Republic, and in 1981 snow cover observations began (Fig.4). The
samples taken are analyzed to measure Ca+2, K+, Na+, NH'4, S02-4, CI-,
NO3, pH, specific electric conductivity. Monitoring of precipitation and
atmospheric chemical compositions is carried out at the station for
transboundary pollutants transfer observations at Rucava. The programm of
works follows the EMEP recommendations. Methods for chemical
analyses have been worked out at the Norwegian Institute for Air
Research (NILU).
968
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Atrnosphnric aerosols (sulphate, ammonium, nitrate) sampled annually
number 150-200. Samples oi atmospheric precipitation (sulphate, pH,
sodium, calcium) amount to 100-150 and of atmospheric air (sulphate
dioxide, nitrogen dioxide) - 150-200 units/year.
Since 1992 air samples have been taken to measure volatile organic
compounds (VOC), and since 1993 ketone and aldehyde measurements
made. Chemical analyses have been carried out by N1LU.
With respect to pollution assessments at the EMEP stations, density data of
fallouts of nitrogen and sulphur compounds arc the most significant (Fig.5).
Within the EMEP programm, an International Meteorological Synthesizing
Centre (MSC-V) makes model based calculations of transboundary
transfer, fallouts and concentrations of harmful substances in Latvia. In
turn, the Republic provides for MSC-V annual data on harmful
substances emissions.
Iri 1992-1993 Latvia prepared and submitted information to join GAW WMO
Prospects in the development of the atmospheric pollution observation
service envisage establishing control over ozone concentrations and
greenhouse gases (carbon dioxide, methane, nitrous oxide,
chlorofiuorohydrocarbons).
Such observations must be accompanied by the activities of the Latvian
Environmental Protection Committee directed towards keeping of National
Cadastre of anthropogenic emissions from the sources, drawing up,
carrying-out and up-dating of a national programme, that contains
measures to mitigate implications of climate change by solving the issues of
antropogenic impact and promoting adaptation to climate change.
The National service of the air pollution observations is now facing
objective difficulties of formation:
- in order to meet the public wish to have one ' supermarket" to serve the
demands for a more wide ecological information, and the necessity to
systemize current and past information on observations, creation ol a
national data bank is an essential aspect in the work to be carried out: at
the same time there is serious shortage of computers and data
processing software:
- in view of the importance of observation and research products, public
interest in ecology, and of an increasing demand for various consultations
for decision - making in economic activities, running of approved scientific
methods for the assessment and verification of the results available
before their publication is of great importance. That's why training of Latvian
specialists is necessary to up-grade scientific potential.
969
-------
(n order to put to effoc-t WMO strategy and policy, as well as thn main tasks
of the Service and possibilities to take pari in the wofri-wide climate and
nature-protective activities, one of the greatest difficulties is linked with a low
technical level of monitoring:
- lack of modern instruments and sampling equipment (automated
included);
- lack of modern methods for the determination and analysis of harmful
substances to be used in routine work and in emergency situations;
- lack of modern scientific criteria of harmful and extremely dangerous
levels of the air pollution.
These are the main directions in the development of the Latvian air
pollution monitoring system on the basis of modern international
achievements.
Fig.1. Air Pollution Observations Over the Republic of Latvia
Valmlera
'entspit:
Jupmats
J&keLpUs
LC3LV2
V d I /
m OOSERVATIONS NUMUER.TH0U3
ri tMiyswrny oe hahmum. sous i anci-s\
J THOUS.T /YEAR 1992
070
-------
Fic.2. Density of Harmful Substances Emissions, 1992
VCNTSPILS
VALMIERA
REZEKNE
OLAINE
IIEPAJA
JURMALA
jEKABPILS
DAUCAVPILS
j ~ t/ycar/ km 2
B kg/year/ 1 inh.
0 100 200 300 400 500 600
Fig.3. Harmful Substances Emissions into the Atmosphere, 1992
(% OF THE TOTAL)
21.9
1.6.,
2.2
n DAUGAVPILS
El JEKABPILS
@ JURMALA
•J/ : ¦'
DLIEPAIA
fen
D OLAINE
O REZEKNE
0 RICA
B VALMIERA
¦ VCNTSPILS
0 OTHERS
60.5
971
-------
Fig.4. Precipitation Pollution Observation Network
Vaimiera
DnnspjtB
zoson
Stand*
Aiukcnp
jurma'a
RIGA
^ - Balozl
Alzputo
nfckAbpas
RUC»UA
~augatfpfls
FTtFClPITATlON POLLUTION OBSERVATION
v' STATIONS
• SHOW I'OUJU T ION OUSEBVA1IQN SI AT IONS
0 STATIONS OF IWTCGHATLD MONITORING
Ftc.5. Fallouts Density ( g/m2), Station Rucava
}~ 1989Q 199013 1991 O 1992a 1993|
SULPHUR COMPOUNDS
NITROGEN COMPOUNDS
972
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({valuation of the Effects of Humidity oil the Transfer of
C2-C10 Hydrocarbons from Cylinders
Ron Bousquel and Ron Brundc
ManTech Environmental Technology Incorporated
Research Triangle Park. NC 27709
Wc prepare complex mixtures of VOCs in 1.5 liter high pressure cylinders.
These cylinders arc used as proficiency lest samples. Audit materials of this type arc
usually prepared in humidified SL'MMA™ polished canisters. Wc compared the
lucoveiy of high molecular weight compounds in humidified canisters and high
pressure 1.5 liter cylinders. A high pressure 1.5 liter cylinder containing C2-C10
hydrocarbons at the 5 ppbv level was prepared by diluting a master cylinder
containing these compounds at the 50 ppbv level. The contents of this small cylinder
were used to prepare a humidified SUMMA polished canister. The relative humidity of
the canister was approximately 50 percent and the final pressure was about 45 psia.
Both the 1.5 liter cylinder and the canister were analyzed and compared lo a
calibration curve prepared using the master cylinder. Recoveries for high molecular
weight compounds in the humidified canister were greater, and closer to the theoretical
values than in the 1.5 liter cylinder used to prepare the canister. This may happen
because the contents were properly delivered from the small cylinder lo the canister
but that humidity was needed to deliver the higher molecular weight compounds lo the
detector.
The information is this abstract has been funded wholly by the U.S. EPA. II
has been subjected to Agency review and approved for submission to the A&WMA.
-------
Compound Break-through Comparison on Different Trapping Materials
Wendy L. Ballard
Sharon P. Reiss
Richard A. Jesser
Graseby-Nutech
4022 Stirrup Creek Drive, Suite 325
Durham,NC 27703-9000
ABSTRACT
Many air analysis techniques require concentrating volatile organic compounds from asample
stream onto a trap for subsequent detection. The aim is to convert a large sample volume at low
concentration lo a small injection volume at higher concent ration. Small injection volumes are more
suitable for analytical techniques such asGC/MS. Sample concentration accomplishes two important
functions for analysis. It concentrates the sample to introduce asufficicnt mass of analytes to available
detectors and reduces the volume to one which can be managed by the analytical system. In whole air
analysis this is accomplished during the analytical procedure using some type oftrap. The trapping
technique must therefore retain the compounds throughout the concentration event without significant
loss due to rhigration of anaiytes through the trap. As regulatory limits for toxic compound exposure
are lowered, the ability to trap larger sample volumes in analysis has increased importance.
Sample concentration has been performed using adsorbent and cryogenic trapping for many
years. When a targeted compound migrates completely through the trap prior to the completion of the
concentration period it is referred to as break-through. The purpose here is to examine break-through a:
a function of sample volume for a number of compounds representative of current demands. Data
presented will help define limiting factors and provide comparative information for various traps.
INTRODUCTION
Lowering detection limits and obtaining both consistent andaccurate results for a growing
number of compounds are some of the challenges facing the analytical chemist in ambient air analysis.
Trapping a larger volume of sample is one approach to this problem. The ideal trap will hold
compounds of multiple characteristics over the entire sampling period, trap 100%ofthe sample target
compounds, release ! 00% of the sample compounds without altering them and itself be unchanged in
effectiveness after multiple uses. In reality the effectiveness of a trap is often limited to a specific
compound group, subject to break-through of compounds, effected by humidity and concentration of
the sample and effected by rate and volume of sample introduction. This study focuses on break-
through characteristics as a function ofvolume for several traps. The compound set chosen is meant t
represent a variety of compounds characteristic in ambient air analysis. The study does not evaluate
the effects of humidity, temperature, or combined trapping techniques. Other relevant literature is
sparse or prepared many years ago with other applications as the focus. Some studies have focused o
field collection of source level samples.
BODY
Three different types of adsorbent traps and the cry otrap were evaluated for recoveries of four
representative compounds. The cryotrap is a well known arid widely utilized trapping technique in th
air analysis field. It consists of fifteen and one half inches of eighth inch diameter Nickel tubing. T!
middle four and one half inches are filled with nun-silanizcd glass beads (60/80 mesh) obstructed at
either end with glass wool (l-'igure 1). The tubing is coiled around a heater which is then wrapped in
-------
tape. The thermocouple is placed for optimum temperature readout of the trap and wrapped in place.
This is then encased in a chamber which provides cooling space for the liquid nitrogen.
For consistency, each trap was configured identically and the amount by weight of each
adsorbent was measured. This was accomplished hy weighing the Nickel tubing before and after
introduction ofthesorbent. The gran: weight of the sorberit used is recorded on Figure I. Each trap
was checked after packing to assure that a SOml/min flow was achievable. Data was collected using a
Nutech mode! 853.') configured with an 11P589011/5971 GC/M.S(Fig;ire2).
Benzene, chloroform, and acetone gas standards were made by iniectinga calculated volume of
neat standard into three separate static dilution bottles. The standard concentration in the static dilution
bottles was calculated to introduce lOOngofeach compound ina200ul injection volume of gas. The
standards were stored at X degrees until usage. Prior to analysis the standards wore heated in an oven to
45C then removed and allowed to equilibrate to room temperature.
Ethane was purchased at a 10.1 ppm concentration and was introduced by loop injection
technique. Using a 5.5ml volume loop in the loop pathway of the 85 33, 68ng of ethane were introduced
to the trap. This technique did not allow for a direct injection therefor aii recoveries were based on the
initial 12.5m! lie volume injection. The two traps that managed to trap ethane showed consistent
results and it can be extrapolated that the traps held the entire iSKngofethane with no break-through on
the initial and subsequent injections.
For each trap a direct injection was acquired in order to establish an expected response. Direct
injections were made through injection port 2 of the 8533 by-passing the trap. A cry ofocusscr was used
to focus the standard on the head of the column prior to injection. The GC was programmed to
optimize detection for each compound specifically.
After establishing the expected response, the remaining injections were made through injection
port 1 onto the trap. Each injection was followed by a given volume of helium introduced through a
mass flow controller at 50m!/min. After the given volume was collected, the trap was rfesorbed and
refocassed on the head of the column by tliecryofocusser. The desorption time for each trap was
optimized to allow a.'l of the introduced compound to be released. Desorption temperatures used were
those recommended bythe manufacturer.
Each compound was individually introduced to the four traps to evaluate the trap performance.
To understand the responses we will iook briefly at the functional theories of each trap. The premise by
which thecryotrap works is somewhat different than that of the adsorbents. As the kinetic energy of the
molecules is minimized due to temperature, weak Van der Wals forces are formed with the surface area
if the glass beads Upon heating compounds revolatilizeand continue to pass through the trap leaving
io residue behind and leaving the trap fully intact for the next usage.
While the efficiency of adsorbent traps can be enhanced by using a cooling mechanism, the
idsorbent itself functions to retain '.he compound on the trap. Various adsorbents are more or less
ffcctive depending on the properties of the compounds and the adsorbent itself. Sorberit materials arc
lassified by mesh size, indicating the particle size. A mesh size of60/80 means that a screen with 60
vires per inch contains holes big enough for all sorbent particles to pass through and an 80 wires per
-ich screen is too small for the so: bent particles to pass through. Soibents are often characterized by
leir pore size and surface area. Each sorbent has a structure that contains openings into which
ompounds, if not higher than the pore size can move into. The greater.surtace area available for
impounds to interact with the sorbent, the greater the likelihood that tiie compound will form a weak
rmdaria be retained on the sorbent material. This may serve as an effective trapping mechanism so
ngasall the compound can be removed. Some compounds may form bonds that are harder to break
an others. The stronger liic interaction between the sorbent and the com pound, the more energy input
needed to remove the compound. Carbon based sorbents such as carbon molecular sieve have a
gherdesorption temperature because they hold tightly to compounds.
Sorbents are commonly known to release "artifacts". Artifacts can be compounds leftover from
cvious sample runs that have not been removed during desorption or rccondi'ioning of the trap.
975
-------
Residual compounds can interact with sample matrix compounds held in close proxinvy by the sorbent
structure or with the sorbent materia' itself. Utah desorption temperatures encourage these interactions.
Other artifacts are by-products fronr. repeatedly heating the sorbent and can increase as the trap ages.
The flow can be restricted by sorbents with small particle size because of decreased air space in
the trap. Tunneling is another flow problem that can sometimes occur with sorbem materials and
reduce the trap efficiency. This happens when the sample stream follows a route through the sorbent
particles rather than flowing evenly through the entire trap. Using a narrow diameter tubing as well as
consistently packing the trapean reduce the chances of this type ofproblcni.
The graphhuw! carbon blacks ofCarbopak™-B are designed for trapping C4-C8 compounds as
we'.! as large molecules such as polychlorinatcd biphenyis. The entire surface of the adsorbent
partic les(<»0\8O mesh) are available for interactions by dispersion or I .ondon forces. The large surface
area(K20m'7g) and smalt pore size of CarbostcvcTMS-111, a beaded carbon molecular sieve, make it
particularly well suited for Hupping small :nolecuiessuch as the C2 hydrocarbons. Carbopak"M and
Carbosieve'" adsorbents typically need higher desorption temperatures than Tenax®. Tenax-TA® is a
synthetic, porous polymeric material used for trapping semi-volatile and volatile organic compounds.
'I he volati le compounds chosen in this study represent some of liw most common compound
sets analyzed for today. Ethane is a very light hydrocarbon found on the ozone precursor hst and one of
the most challenging to capture. A common organic solvent, acetone, represents the polar compounds.
Chloroform is a halogenated hydrocarbon found on the TO 1-1 compound list. The aromatic
hydrocarbon benzene is one of the BTEX compounds. T> pical umbientsamples range from less than
0.2npbvas high as 1 OOpnbv. The majority however fa!• between 0.2 and 2(>ppbv. Assuming a 2pphv
ambient air sample is to be analyzed, a five hundred milli liter vol time collected on a trap would
introduce 3.2ng benzene. 4.9ngchioroform, 1.2 ng ethane, and 2.4 ngacetone on the trap.
CONCLUSIONS
Reviewing '.he data we find that thecryotrap performed optimally for all challenge compounds
(Graph/Tabie I). This is so because the trap does not depend primarily on the characteristics and
interactions oft he sorbent and compound, but on the temperature. The trap has a minimal desorption
lime and temperature to retrieve all compounds. There is no concern for carryover or artifacts from the
cryotrap.
Carbopak™ B trap showed consistent results for benzene up to two liters. Acetone began to
break-through after 500ml and chloroform recoveries were a: 86 % a; 100ml and continued to drop until
1 OOOtni where they stabilised at27% recovery of compound from the trap (Graph 'Table 21. It is not
surprising that ethane was not retained by the ".rap at all since it is designed for heavier hydrocarbons,
Carbosieveu,S-lll trapped both ethane and benzene very effect: veiy. Acetone responses were
consistently at 70%and could not he improved by longer desorption time or raising the desorption
temperature (Graph/Table 3). Chloroform had unexpectedly low recoveries This may be a reflection o
compound decomposition rather than break-through.
Tenax® is the final sorbent evaluated in this study (Graph/Table 4). Tenaxfli1 showed break-
through on all challenge compounds i:i this stud\. Ethane, being the lightest was not trapped at all.
Acetone and chloroform recoveries were good for a lOOmi volume sample. Benzene recoveries were
good to a volume of 1250ml after which so me break-through occurred. TenaxfP is frequently used in
combination with other sorben'.s because of its low break-through volumes for compounds.
This study succeeded in characterizinftthe performance ofsome currently available sorbentsas
trapping materials for sample concentration prior to analysis. For the purposes ofthis study, the
cryotrap was able to perform for all compounds up to a two liter sample volume. Other studies could
develop the sorbent (rap by using lower'err.peratures for trapping and by combining sorbent materials.
Analysts interested in a specific compound set may use this information to determine an appropriate
sorbent material or trapping technique in analysis.
976
-------
FIGURE 1
DIAGRAM OF TRAP
15.1/2" l*ngtfi of
118" NIcMe tubing 4.5" Sorbent Matarial
0.5" 0.5"
Glass Wool Glass Woo!
Tenax-TA® -115 mg
Carbopak B -151 mg
Csrbosieve S-lll - 320 mg
Model 8533 Universal Sample Concentrator FFGURE 2
JlVQCtlOtt
Port #1 Caltwatio-i G*s
•Pr.
Sample
Loop
V1
Carrier 1
OC
V5
Cryolrap
V3
OC
977
-------
GRAPH 1:
Cl
B.
120% T
100%
80% J-
50%
40%
i
i
20% !
Compound Recoveries on the Cryotrap
•100ng Benzene |
- 100ng Chloroform'
•G8ng Ethane i
- 100ng Acetone j
0% i
Direct
inject
12.5m) 100ml 250m) 500ml
Purge Volume on Trap
1000ml
2000m!
TABLE 1:
Area Response
Benzene
Chloroform
Ethnne
Acetone
l>rect irject j
1 TfiTlQ","*! «
12639754 14262944 '
1X1C20S
5257G&4
1443S*J34
Hdiurr ^unje volume of trap
_ SCmi . 100-r,'. _2dOti! SDOml
14479S4S" ~ 10000692 "'14343571'" T290376T
1?O45S?0 12R6O750 130S?45G
5426G92 to25*ja2 5G01048
KOOOG6S 1473b222 14104519
_ 10CCrrl
~ 13751994~
125036?6
tfCossea
14647264
1380970!
12347471
Percent Recovery
Helium Pj-ge volume of trap
Z*ccljn[cct_
125-n'
bCrrl
1CGr.»
SCOrnl
100Crrl
2C00m!
Benzene
iou% t
113%
110%
1-.9%
117%
102%
ioe%
109%
ChlorykJt in
10C% j
1&i%
134%
103%
1C4%
100%
90*
Ethane
— i
100%
—
im
105%
107%
107%
Acetone
iook
112%
113"fc
r,b%
110%
114%
10?%
-------
GRAPH 2:
Compound Recoveries on Carbopak B
J
lOCr^ 8«vsrw
iMoy fhofc'otn
lOim: 90£m. 'OCCmi 20Can;:
I than* i»iw* Ca-!x*;.»k t> is v-jdy Pi.tfie Vctur* o Tiap
waaitflP 3i'C
Orsoffi l*''ip ?r>WC
TABLE 2:
Area Response
He'um Purge volurre of t*a p
C'rect inject j 12.5m' _ _ ICOrrl _ 250mi 500m!
Benzene 11540443 | 12440 7/6 12C21514 — 11991914
Chloroform 100'6C/9 j 9&S354 / 86tt!5/4 /GS32 O 6379318
Acelonp {5990033 • G474?06 lOf.15236 102774*1 SP?4?>*7
1030ml ^?OOOfr£
121248CS 12C71391
26132b1
7475362
27b141g
814076
Percent Recovery
Benzene
Chloroform
Acetone
Direct inject
10C%
100%
"00%
12 5irl
'OOm:
i Purg* volume of trap
25Crn! 500ml
1000ml
107%
95%
95%
1C3%
86%
1CC%
77%
103%
'03%
7C%
96%
104%
26%
75%
Ethane is not reamed on Carbopak B in this study.
Load tump: 31 *C
Desort) t«np: 250'C
979
-------
GRAPH 3:
120% r
i
Compound Recoveries on Carbosieve S-IIJ
£ I\\
> 80% \
8 i \
a 90% | \
c I \
® i \
a 40% | N
a I
O- I
20% | -
. ; ¦—*— I00ng Benzene |
\ 100ng Chloroform |
\ - : ¦ ¦ "68ng Ethane j
A :—©—100r.g Acetone I
0% J-
Direct
inject
Load Temp: 31CC
Desorb temp: 270°C
12 5mi 100ml 500ml 1000ml 2000ml
Purge Volume on Trap
TABLE 3:
Area Response
Heiicm Purge volume of trap
_Djrect mject . *2.5fn1 25QtiI_ 5C0ml
Benzene i1C£G244 11654433 1133*743 — H241S62
Chloroform 9775740 *35C24* 1199745
Ethane —- i 5476503 55432fi7 5490S75 542263'.
Acetone '.08674 06 «4255>.® 7707658 BCC7399 S021018
_ lOOCrrjl 2000ml
12452 <*37 1 0350312
5107689
7947109
Percent Recovery
Benjene
Chloiolorm
Ethane
Acetone
Heliurr. Purge vciume c' trap
•cd in;«rc:
12.5-al
100ml
__ ..250ml
50CfT'._
lOOOrri _
2000mJ
103%
| 105%
102%
—
101%
112%
93%
100*
14%
'.2%
—
—
*C0%
99%
100%
99%
95%
100%
i 7 f%
/0%
73%
73%
72%
67%
Load terr.p: 31*C
Dgsorb temp* 270*C
980
-------
GRAPH 4:
Compound Recoveries on Tenax®
%
o
o
0>
100ng Benzene
100ng Chloroform
100ng Aceione
\
100m,
Direct inject
Load (emp: 33°C
Desorb lemp: 200"C
Ethane is not retained on Tenax® in this study.
500ml
Purge Volume on Trap
1250ml
2000ml
Area Response
Helium Purge vc^mo of tis^
Direct ir.jfrct
12.5ml
lOCm.'
250m,
500n!
100Chi
125Cknl __
1500nl
2XK>nl__
Benzene
13*9/58
1261 UfcSJ
—
1223lx>3
Ti7zsw~
i:yw7se'
TO2'"'
Chlu/x>Jo»m
1060S4S9
10390862
103663C5
S1S7952
7168075
131139
—
AcHcrv?
1040S4?9
t0682373
107C2240
330062c
781457
-
Benzene
Ctifcroform
Acetone
Qredjnject
"" '100%'"
130%
12.6m'
" 112%"
S0%
103%
Percent Recovery
Heli j-n Pj'je veiurte of bap
_ _?5Gm; _ _50Gml JOQ&rt
1%
100%
se%
1C3%
77%
32%
105%
63%
8%
1253ml
103*
JSOOnL
73%
20COrnf
18%'"
98 i
-------
Evaluation of Modifications to the Tekmar™ 5010 for the
Analysis of Indoor Air Pollutants on Multisorbent Tubes
John W. Duncan
ManTech Environmental Technology Incorporated
Research Triangle Park, NC 27709
Solid sorbents, such as Tenax™, may be used for the collection
of complex chemical pollutants. The pollutants are desorbed from the tenax at the head
of a GC column and analyzed by various detectors. Tenax and other sorbents may be
packed into tubes of various sizes and shapes. Because we provide quality assurance
support to a wide variety of projects, our equipment must be adaptable to may sample
types. The Tekmar™ 5010 automatic desorber has furnace sizes capable of desorbing
seven inch tubes of 5/8 inch and 1/4 inch diameter. Desorbing other, multisorbent bed
tubes thai are eight inches long requires a modification to the furnace cap. We have
designed and buill a replacement cap for the 1/4 inch furnace that allows the Tekmar
5010 to desorb the eight inch multisorbent bed tubes. The modification is simple
enough to be performed by small machine shops. This modification increases the
flexibility of existing equipment. Details of the modifications are provided along with
an evaluation of its performance.
The information in this abstract has been funded wholly by [he U.S. EPA. It
has been subjected to Agency review and approved for submission to the A&WMA
982
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Evaluation of Storage Conditions for Indoor Air Pollutants on
Solid Sorbents in UHP Helium Purged Mylar™ Packs
John W. Duncan and Frederic J. Mixson
ManTcch Linvironmcntal Technology Incorporated
Research Triangle Park, NC 27709
Solid sorbents. such as Tcnax™, may be used for the collection
of complex chemical pollutants. The pollutants are desorbed from the lenax at the head
of a GC column and analyzed by various detectors. Many laboratories pack Tcnax into
glass tubes of various sizes and shapes. Shipping and storage of both clean and used
Tcnax cartridges are problematical due to the fragility of the glass tubes. This
laboratory provides audit materials for a wide variety of projects, and an optimum
shipping and storage system will maintain sample integrity and protect against
breakage. Sealing cartridges in a Mylar™ package purged and slightly pressurized
with ultra high purity helium provides an inert environment, and helps to maintain
sample integrity. The sealed package also provides a protective bubble-like
environment perfect for shipping. The preparation method is described and the results
of stability studies reported for important indoor air pollutants when compared to
traditional storage methods.
The information in this abstract has been funded wholly by the U.S. lil'A. It
has been subjected to Agency review and approved for submission to the A&WMA.
983
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Environmental and Occupational Exposures to PAH In the Czech Republic:
Personal Exposure Monitoring Coupled with HFLC/Time-Programmed Fluorescence Detection
Ron W. Williams
Karen E. Hattaway
Integrated Laboratory Systems
P.O. Box 12199
RTP, NC 27712
Randall R. Watts
Joellen Lewtas
US Environmental Protection Agency
MD-68A
RTP, NC 27711
ABSTRACT
The US Environmental Protection Agency has collaborated with health researchers in the Czech
Republic to determine polynuclear aromatic hydrocarbon (PAH) exposures for populations in highly
polluted environments and in various occupations. These investigations used personal exposure monitors
(PEMs) that were developed to allow separate and simultaneous collection of fine particles, vapor phase
nicotine and vapor phase organics. Samples were extracted and analyzed for 16 priority PAHs by
optimized HPLC coupled with time-programmed fluorescence detection. Nicotine analysis was
performed using capillary gas chromatography with nitrogen-phosphorous detection. Personal exposure
monitoring periods of up to 24 continuous hours were conducted for: 1) Teplice and Prachatice
policemen, who spent a major portion of their day outdoors: 2) open-pit coal miners: 3) health
researchers working in a laboratory; and 4) coke oven workers. Total particle-bound PAHs ranged
from 1.5 iigfnP for the health researchers to 52 ng/m3 for the topside coke oven workers. Vapor phase
PAH concentrations also varied greatly depending on occupation and ranged from 0.6 pig/m3 for city
policemen to 261 ftg/m3 for the coke oven workers. Carcinogenic PAHs, which were predominantly
found associated with particulate matter (>90%), typically included benzo(a)anthracene, chrysene, and
benzo(a)pyrene.
INTRODUCTION
The Northern Bohemia area of the Czech Republic has been heavily polluted from source;
associated with the industrial and residential uses of high-sulfur brown coal1. This coal, found in
abundance in the region, is used in coal-fired power plants, chemical processing sites and for busines
and residential heating. Fossil fuel contribution from mobile sources as well as pollution from coal am
other emissions have resulted in Czech Republic concerns over possible human exposures to hazardou
agents such as PAHs. Czech scientists associated with the Teplice District Institute of Hygiene hav
been working with the US Environmental Protection Agency in efforts to quantify personal exposure
to PAHs in the Teplice District of Northern Bohemia2. This site, centrally located in an area of heav
coal mining and utilization offered opportunities to evaluate personal sampling methodologies an
investigate the relationship between PAH exposures and selected occupations.
984
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STUDY DESIGN
Four occupational groups were personally evaluated for PAH exposures. Groups consisted of:
1) Teplice coal miners, 2) Teplice and Prachatice policemen, 3) Teplice health researchers, and 4)
Ostrava coke oven battery workers. Coal miners monitored were involved in open pit mining of the
high sulfur brown coal. Their main duties involved mechanical repair of large, outdoor, conveyor belts
that moved excavated coal from extraction points to transportation and storage sites. A noted feature
of these open pit mines were in-ground coal fires which continually bum. The combustion emissions
from these point sources fill and often envelope the open pits (bowls) and therefore inversion-like
episodes occur. A group of Teplice policemen were involved in the study. These were largely
involved in foot patrol of the central business district (CBD) of the town of Teplice. It was postulated
that monitored individuals would be exposed lo coal combustion emission products associated with
heavy industrialization and residential heating along with mobile source emissions from automobiles and
buses. Emission control devices on most automobiles and buses, upon visual observation, did not
appear to retard pollutant emission. Prachatice policemen, who live in a relatively pristine area of
Southern Bohemia were also monitored as a control group where PAH concentrations were presumed
to be near background levels. Health researchers associated wiui the Teplice District Institute of
Hygiene were monitored for PAH exposures. These individuals were involved in laboratory research
as well as project management and were generally indoors. They were postulated as being exposed to
urban air similar to that encountered by the Teplice policemen but at levels reduced by the modifying
effects of being indoors.
The fourth occupational group monitored did not reside in the Teplice mining district. These
were coke oven battery workers from a site in Ostrava. This group was selected due to known PAH
exposure among coke oven workers and as a means to evaluate the samplers ability to collect PAHs
under high concentration conditions. Larry car drivers (outdoor-topsidc workers), pushing machine
helpers (outdoor-lower level workers), and quench car drivers (outdoor-ground level workers) were
monitored. Larry car drivers are highly exposed individuals involved in dispensing coal charges into
open and venting oven portals. Combustion emissions, constantly being released by the 24 hour/day
coking process results in a thick fog of coal combustion emissions at the top of the coke oven battery.
Pushing machine workers are involved in forcing the processed coke from the furnace using a large
mechanical ram. This is conducted at the base of the oven (side) where point sources, and the emission
plumes, are considerably less than atop the coke ovens. Quench car drivers are involved in
transportation of coke extruded by the pushing machine to quench stations where cooling and particulate
suppression procedures are conducted. This operation is generally conducted at ground level using
motorized carts or conveyor assemblies.
PAHs, collected using battery powered personal exposure monitors (PEMs), would be collected
ind extracted for analysis. Sample collection would consist of periods from 8-24 continuous hours with
simultaneous capture of both particle and vapor phase PAHs. Vapor phase nicotine, resulting from
;nvironmental tobacco smoke (UTS), would be collected to investigate cigarette smoke contribution to
otal PAH levels. Dichloromethane extraction would be utilized to extract PAHs from collected
esplrable particulate matter (RSP) and macroreticular resin (XAD-2). Solvent exchanged extracts
vould then be analyzed using high performance liquid chromatography equipped with a PAH specific
nalytical column as well as time-programmable fluorescence detection. Vapor phase nicotine, collected
s a stoichiometrically bound reaction product with sodium bisulfate, would be extracted and then
nalyzed using capillary gas chromatography with nitrogen-phosphorous detection.
IATERIALS AND METHODS
Personal exposure monitors (PEMs) consisted of an inert, modular designed inlet, impactor,
Iter pack, and resin chamber assembly connected to a lightweight sampling pump. Detail about this
;vice has previously been reported2-3. In brief, a Teflon coated aluminum inlet was utilized to collect
trticulate matter and focus particles >2.5 ptm onto a coated impactor surface to remove it from the
•>S'.5
-------
sample to be analyzed. The RSP stream was then forced into a three-stage Teflon filter pack. The first
filter stage, consisting of a 2.5 cm Teflon impregnated glass fiber filter (TIGF), was used to collect
particle phase PAHs. The second and third stages contained identically prepared sodium bisulfate TIGF
filters used in vapor phase nicotine collection. The mechanism by which nicotine is collected in this
manner along with extraction and analysis procedure using this technique has been reported2,4. Vapor
phase PAHs, pulled into the filter pack, but not collected at this point, pass through a 2.5 gram bed of
styrcne-divmyl benzene (XAD-2) where retention occurred.
PEMs were individually issued to each respondent after sampling rate calibration was performed.
At the end of each collection period, PEMs were recovered, final sampling rate determined, and filter
and XAD-2 samples recovered. A sampling log was utilized to document the effort as well as note any
irregularities. Filter samples, PAH and nicotine separately, were transferred into light protected
borosilicate vials equipped with Teflon lined closures while XAD-2 units were sealed using Teflon
screw caps designed specifically to seal the PEM's resin chambers. All collected samples were returned
to the Health Effects Research Laboratory (US EPA, RTP, NQ for extraction and analysis.
PAHs collected upon TIGF filters were extracted using three (sequential) 7 ml portions of
dichloromethane (DCM) added to the vials containing each filter. Each extraction period consisted of
10 minutes of sonication at 25°C. Extract from each attempt was ultimately pooled, filtered through
a 0.45 (im Teflon, and volume reduced to 10 ml using nitrogen evaporation. Vapor phase PAHs
collected upon the XAD-2 resin were extracted using 25 ml of DCM. This was performed by "eluting"
DCM through the actual resin chamber used to collect the sample. The resin chamber (made from
Teflon) was designed to accommodate just such a procedure. This flow-through extraction technique
minimizes possible XAD-2 contamination from laboratory and field artifacts by not having to remove
the resin from the collection device to permit solvent extraction and analyte recovery. Extract from
each resin chamber was individually captured into borosilicate tubes, filtered through 0.45 ftm Teflon,
and solvent normalized to 10 ml using nitrogen evaporation. Portions of the filter and XAD-2 extracts
were then solvent exchanged into 100% acetonitrile to accommodate reverse phase HPLC analysis of
the PAHs. Nicotine, collected using the sodium bisulfate treated filters, was recovered using procedures
referenced earlier. Bound nicotine was released from the sodium bisulfate using sequential treatments
of 5% ethanol followed by basification (10N NaOH). The resulting nicotine free base was then
extracted into an organic layer of ammoniated n-heptane. Portions of this phase for each nicotine
sample were individually transferred into autosampler vials for capillary gas chromatography.
PAH analysis using time-programmed fluorescence analysis was conducted using procedures
discussed in depth elsewhere2,4. This procedure involves use of a PAH-speeific reverse phase HPLC
column to optimize resolution between the 16 Priority PAHs. These PAHs are listed in Table I.
Time-programmed fluorescence analysis is a technique that utilizes the optimum individual (or group)
excitation and emission wavelengths for the PAH of interest. This technique has been found, in ouj
hands, to be almost 3 orders of magnitude more sensitive that capillary GC-flame ionization detection
Because optimized detection is utilized, interferences from species of non-interest present in the extract
are greatly minimized.
RESULTS
A comparison of particle phase and vapor phase PAHs collected for the Teplice Distrk
respondents is presented in Figure 1. These graphs reveal that vapor phase PAHs (like naphthalcm
phenanthrcne, anthracene, etc) account for the majority of the total PAHs detected in the Teplic
district. This was true for all of the Teplice occupations monitored. The Teplice miners were expose
to the highest overall levels observed with some individuals exposed to as much as 10.3 ^g/m5 of tot
PAH with less than 0.5 pg/m3 of this accounted for by particle phase PAH. While the numbers •
individuals sampled were too small to allow a statistical comparison between the groups (n=3-
patterns were observable. The Teplice health researchers were determined to be the least expose
This was not unexpected due to the amount of times these individuals spent indoors daily. It was al
expected that the Teplice policemen, monitored in January, would have exposures greater than the heal
986
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institute workers but less than the miners. Note that when these same policemen where monitored in
March, at the end of the winter inversions, PAH concentrations fell 2-3 fold. We have observed this
phenomenon in other studies at this site. Prachatice policemen, presumed to have little PAH exposure
due to the lack of heavy industrialization in Southern Bohemia, were found to have the highest level
detected (10.9 /ig/m3 of total PAHj Vapor phase PAHs dominated this result. Investigation of this site
revealed that while little industrialization is present in Prachatice, there is a high occurrence of
residential heating using coal in this mountainous town. This source is believed responsible for the
majority of PAH exposure.
Carcinogenic PAHs were predominantly observed to be collected in the particle phase. This is
detailed also in Figure 1. Carcinogenic PAH exposures follow the same ranking as that observed for
total PAH (Teplice miners>Teplice policemen>Teplice health researchers). Species such as
benzo(a)anthracene, chrysene, and benzo(a)pyrene were observed in the highest concentrations of the
particle phase carcinogens. Teplice miners were determined to be exposed to levels ranging from 90-
340 ng/m3. Note that carcinogenic levels detected for the Teplice policemen fell to those of the
Prachatice policemen control group during a March retest at the end of winter inversions.
Coke oven workers, an occupational group known to have an epidemiologically investigated rate
of cancer, were exposed to as much as 30 fold higher PAH concentrations than the Teplice citizens
(Figure 2). Larry car workers (like respondent #10) performing an 8 hour shift atop the coke oven
battery, had monitored levels of over 300 /xg/m3 total PAH. Patterns between the various worker
assignments typify the examples included here (24 total workers were monitored at the site). Topside
workers, like the larry car drivers, are exposed to much higher levels than workers whose jobs arc
performed on the side or ground level of the coke oven plant (pushing machine or quench car workers).
This is mainly due to the way in which coal is processed into coke and the point source emissions that
result. The PEM utilized to collect PAHs (and the high particulate matter levels observed at the plant)
had no detectable problems with filter overloading or vapor phase breakthrough of the XAD-2 resin at
the concentrations encountered.
Nicotine, as a marker of environmental tobacco smoke (ETS), was monitored for all of the
Teplice study groups to determine the level of PAH contribution from this source. ETS was not
observed to heavily influence any measurement of PAH (Figure 3). Nicotine concentrations, noted by
the + symbols and solid lines in the figure, did not appear to follow any pattern of observed PAH level
for monitored respondents. This result probably indicates that PAH contribution from ETS sources are
inconsequential to those from the other sources in this study (like coal combustion or mobile sources)
when a highly polluted environment is monitored.
CONCLUSION
The PEM system utilized was determined to successfully monitor particle and vapor phase PAHs
as well as vapor phase nicotine. Collection periods of 8-24 hours were utilized at both high as well as
low analyte concentrations. Vapor phase PAHs were observed to be in much higher concentrations than
the particle phase PAHs with most carcinogens collected upon filters. Coke oven workers were
determined to be highly exposed with respect to the Teplice citizens. Teplice citizens, working in
outdoor situations, are more likely to be exposed as compared to those working indoors.
VCKNOWLEDGMENTS
This work was supported by US EPA contract# 68D-300096 with Integrated Laboratory Systems.
)ISCLA1MER
This report, nor data presented therein, does not necessarily reflect EPA policy.
987
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REFERENCES
1. Kotesovec, F., Jclinke, R. and Srara, 'R.-,Preliminary Proposal for a Research Project "Impact of
Environmental Pollution on the Health of Population at the District ofTeplice, Czech Republic", District
Institute of Hygiene, 416 65 Teplicc, Czech Republic.
2. Watts, R.;Lewtas,J.; Stevens, R.;Hartlage, T.;Pinto, J.;Miskova, l.;Benes, I.;Kotesovec, F.;Sram,
R.;Williams, R; Hattaway, K. Int. I. Environ. Anal. Chem. (In press, 1994).
3. Williams, R.,Brooks, L., et al., "Field test and laboratory evaluation of a lightweight, modular
designed, personal sampler for human biomarker studies," in Proceedings of the 1992 U.S.
EPA/A&WMA International Symposium on Measurement of Toxic and Related Air Pollutants,
EPA/600/R-92/131, 1992, 188-194.
4. Williams, R.;Collier, A.;Lewtas, J. Indoor Environment 1993 2, 98-104.
5. Williams, R.;Mearcs, J.; Brooks, L.;Watts, R.;Lemieux, P. Int. J. Environ. Anal Chem. 1994 54,
299-314.
988
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Table I. Priority PAH quantified using HPLC
1. Naphthalene
9. Ben?:o(a)anthracene
2. Acenaphthylene
10. Cbiysene
j 3. Acenaphthene
11. Benzo(b)fluoranthene
I 4. Fluorene
12. Benzo(k)fluoranthene
I 5. Phenanthxene
13. Benzo(a)pyrene
1 6. Anthracene
14. Dibcnzo(a,h)anthracene
[ 7. Fluoranthene
15. Benzo(g,h,i)perylene
8. Pyrene
16. Indcno(l,2,3-cd)pyrene
Compare Total FAHs
Compare Carcinogenic PAHs
ng/Cu-M
(thomaads)
ij
wW
T«p.
htf.
Pwch*fco»
T«pik»
P«lk»
B^CUlM
to I Ml
°t(Tti\CA 7tptC*
Pole* wIl*
Jtitf aii. M
¦1 Partides FZZ XAD
Figure 1. Personal sampler: particle filter compared to XAD for PAH.
989
-------
350
10, 12. larry car driver
300
250
200
. push machine operator/
100
8. quench car driver
Sample No.
H BaP E3 Total PAH E2 Carcinogenic PAH
Figure 2. Personal monitoring of coke oven workers for PAH exposures.
Teplice
Police
60-
Teplice police
£ 40-
30 -
Teplice miners
O)
Teplice
Inst Hyg.
Jan. 9
Jan. 8
Jan. 9
Mar. 9
+ Nicotine ng/cu,m. ® Part. carc. PAH ng/20cu.m.
¦ Part, tot. PAH ng/20 cu.m. ' Part. + XAD tot. PAH ng/cu.m.
Figure 3. Personal sampler comparison of nicotine and PAH
990
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Evaluation of the Transfer Efficiency of High Molecular Weight
Hydrocarbons Using Various Types of Regulators
Ron Housquet
ManTech Environmental Technology Incorporated
Research Triangle Park, NC 27709
We prepare complex mixtures of VOCs in 1.5 liter high pressure cylinders.
These cylinders arc used as proficiency test samples. We also provide a regulator with
those samples supplied lo participants in the PAMS network. Diffeient regulator types
from various suppliers were evaluated for cleanliness, recovery efficiency
and our ability lo reclcan them for use with compounds in the parts per billion range.
All regulators were alternately attached to the same cylinder containing UUP nitrogen.
For each regulator, about 50(1 millimeters of nitrogen that had passed through it were
cold (rapped and analyzed by GC'MS. The number of chromatographic peaks and total
area was recorded. All regulators were then made dirty by attaching to a 20 ppmv
source of VOCs and purging the regulator. The regulators were then cleaned by-
purging with UHP nitrogen. This nitrogen was analyzed as before and the number of
peaks and area was noted. All cylinders were attached to a source of 50 ppbv C2-C10
hydrocarbons and evaluated for relative recovery. Low dead volume, highly polished,
single stage regulators proved to be the regulator of choice for our purposes.
The information in this abstract has been funded wholly by the U.S. lil'A. It
has been subjected to Agency review and approved for submission ?o the A&WMA.
991
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Simplified Preparation of TOW and Title III Air Toxic Standards
Using a Windows Software Package and Dynamic Dilution Schemes
U.li. Cur din and E.A. Galuustian
Entech Laboratory Automation
950 (inchanted Way #101
Simi Valley, CA 93065
The preparation of Air Toxic standards in the laboratory can be performed
using several methods. These include injection of purge and trap standards, static
dilution from pure compounds, and dynamic dilution from NIST traceable standards.
Sialic dilution and dynamic dilution arc the preferred choices as they keep high
methanol concentrations from being introduced into the T014 SUMMA passivated
sample containers (methanol is a TITLE 111 target compound). Using static and
dynamic dilution, standards can be created accurately with the ilexibility to add new
compounds to a laboratory's list of target analytes at a very low cost.
Using static and dynamic dilution in the laboratory to prepare standards
containing 40 to 80 target analytes requires performing complex, time consuming
calculations. To simplify manually performed calculations, corrections for room
temperatures and barometric pressures are sometimes ignored, which can add to the
error in performing these calculations. In addition, mass flow controllers are assumed
to be correct rather than trying to manually determine and implement correction
factors for each flow channel using multipoint calibrations.
A software package running under Windows has been developed that makes
calculating dilution parameters for even complex mixtures fast and simple. Compound
parameters such arc name, molecular weight, boiling point, and density arc saved in a
data base for later .access. Gas and liquid mixtures can be easily defined and saved as
an inventory item, with preparation screens that calculate appropriate transfer volumes
of each analyte. These mixtures can be utilized by both the static and dynamic dilution
analysis windows to calculate proper flow rates and injection volumes for obtaining
requested concentrations. A particularly useful approach for making accurate polar
VOC standards will be presented.
992
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Results from the August 1993 DOAS Evaluation in Baytown, Texas
Charles P. Conner
ManTech Environmental Technology Inc.
Research Triangle Park, NC
Lee Ann H. Byrd
Office of Air Quality, Planning, and Standards
U.S. EPA
Research Triangle Park, NC
Frank F. McFlroy and Robert K. Stevens
Atmospheric Research and Exposure Assessment Laboratory
U.S. EPA
Research Triangle Park, NC
An EPA-sponsored field study lo further evaluate DOAS technology took place
in Baytown, Texas in August, 1993. The goals of the study were to evaluate
calibration and audit procedures and lo further evaluate DOAS performance in an area
with potentially high pollution levels. The gases being measured were uzone, nitrogen
dioxide, and sulfur dioxide. Two separate DOAS systems were operated
simultaneously using nearly identical air paths. Two sets of conventional point
measurement monitors were operated at the site to provide EPA-approved reference
concentration measurements. Hourly-average concentration measurements were
recorded from all measurement systems, Intercomparisons of the various data sets have
been carried out. Excellent agreement between the two DOAS systems and between
the two point measurement systems was seen. The agreement between the DOAS and
point measurement systems varied from excellent to poor, depending upon the gas
being measured. The quality of the correlations between the two fundamentally
different techniques was dependent upon the homogeneity of the air mass. When
nearby sources were present, the pollutant plume at the monitoring site was narrow
enough to differentially affect the two types of monitors. Thus the different techniques
measured different concentrations and the data correlations were degraded.
993
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Effects of Using Nafion® Dryer on Hydrocarbons Analyzed from
Canisters by Modified EPA Method TO-14
John C. Sagebiel and Barbara Zielinska
Desert Research Institute, P.O. Box 60220, Reno, NV 89506-0220
ABSTRACT
Hydrocarbons in the range of C2 to C12 were analyzed from SUMMA-polished stainless stee!
canisters by cryogenic preconcentration, desorption with boiling water and high-resolution capillary-
column gas chromatography with flame ionization detection. Eight samples taken inside a highway tunnel
were analyzed with and without a Nafion® dryer (Perma Pure Products, Inc.). The membrane
successfully removed water and polar species like methanol and ethanol, however, it also removed a
significant amount of the olefins and aromatics and lowered the total measured ppbC by 10-15%. The
paraffins seemed to be less influenced by the membrane. Several other peaks were noted to appear when
using the membrane. We therefore do not recommend using this type of water-removing device when
performing sepciated hydrocarbon analyses.
INTRODUCTION
Water removal membranes are used extensively prior to cryogenic preconcentration in the analysis
of hydrocarbons by EPA Method TO-14 (US HP A, 19881), which recommends the use of such devices
and states that there is "no substantial loss of targeted VOCs..." when using such devices. However,
there has been little discussion in the literature of the effects of these devices when analyzing for total
non-methane hydrocarbons (TNMHC) (Cochran I9872; Coutant and Keigley 19883, Pieil, et al. 19874).
We report here on some preliminary work assessing the effects of the Nafion® dryer (Perma Pure
Products, Inc.) conducted as part of a larger study.
EXPERIMENTAL METHODS
Sample Collection
Samples were collected as part of a study to measure on-road vehicle emissions (Pierson, et al.
19945). The samples reported on here were collected in the Tuscarora Mountain Tunnel on the
Pennsylvania Turnpike in south-centra! Pennsylvania. During this study eleven sampling periods of one
hour were conducted to determine emission rates from on-road motor vehicles. By selecting various
times of day and days of the week, a range of fleet composition (and thus exhaust species profiles) were
obtained. In this study the fleet composition ranged from 20 to 94% light-duty spark-ignition vehicles
with the remainder of the fleet consisting primarily of heavy-duty diesel trucks. For the lighter
hydrocarbons (those generally analyzed out of canisters) there was little difference between the light- and
heavy-duty vehicles (Sagebiel, et al. 19946, Zielinska, et al. 19947). There was considerable atmospheric
moisture during the sampling periods with an average relative humidity of 85%, thus we were concerned
that the moisture would influence the analysis.
Whole air samples were collected in SUMMA-passivated canisters by means of an active pumpec
sampling system designed to fill the canister to about one atmosphere above ambient pressure at the em
of the sampling period. For more details on the collection and methods of the tunnel study, sec I'icrsor
et al. 1994 and Zielinska, et al. 19947.
Sample Analysis
The samples presented in this paper were analyzed twice: once with the Nafion® dryer and one
without In either case the methods of analysis was identical except for the dryer. The method employe
is a modified EPA method TO-14, the details of which are given in Zielinska, et al. 19947. Briefly,
sample aliquot was transferred by use of a vacuum system to a freeze-out loop made fro
chromatographic-grade stainless steel tubing packed with 60/80 mesh deactivated glass beads. The lo<
994
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was cooled by immersion in liquid oxygen The trap was then flash-heated with hot water and via a
rotary valve switched to transfer the condensed NMHC into the gas chromatograph for analysis. The
chromatographic column used was a 60 m long J&W DB-1 fused silica capillary column with a 0.32 mm
inside diameter and 1 |jm phase thickness. To help the chromatographic system deal with the extra
moisture, an approximately I m long section of 0.53 mm id deactivated fused silica tubing was used as a
pre-column. The larger diameter prevented an ice plug from blocking the column. The oven temperature
program was: -50° C for 2 min., to 220° C at 6° C per min, The GC/FID response was calibrated in
ppbC, using N1ST Standard Reference Material (SRM) 1805 (254 ppb of benzene in nitrogen). Since
this column did not provide complete separation of the C2 and C3 hydrocarbons a second
chromatographic run on a J&W GS-Q column was used to obtain values for these light hydrocarbons.
Since the GS-Q is unaffected by water, no attempt was made to remove water prior to this analysis.
Thus the results presented here are for the C4 and above compounds only
RESULTS AND DISCUSSION
The Nafion® dryer has been reported previously (Cochran 19872; Coutant and Keigley 19883;
Pieil, et al. 1987*) to be effective at removing water and other polar compounds without adversely
affecting the major components in the sample. However, in the present study we were quantifying
approximately 160 hydrocarbons species, many of which were present in small quantities. The TNMHC
quantities in these samples ranged from approximately 100 to over 400 ppbC (Table 1), which are among
the lowest concentrations seen in highway tunnel measurement, and is even lower than would typically be
seen in ambient air measurement in urban areas. As a result, a larger volume of air had to be transferred
to the freeze-out loop and subsequently a larger amount of atmospheric moisture. This extra moisture
presented a problem and resulted in the loss of resolution for some compounds. However, after assessing
the effect of the Nafion® dryer we decided not to use it for the tunnel project
The effect of the Nafion® dryer on the major groups of hydrocarbons is presented in Table 1.
The paraffins were generally less affected than were the other groups The non-HC grouping consists of
oxygenated, chlorinated, and other compounds found in the sample. These are generally strongly
removed by the dyer, as is expected. One sample (EPR9) suffered significant losses from all three groups
of compounds. This is an unusual case and may not be representative of the effect of the dryer.
Some selected compounds from sample EPLI are presented in Tabic 2. These are grouped the
same as Table 1, and are in order of highest concentration to lowest Again, the paraffins are influenced
very little, while some of the olefinic species are influenced very strongly. Among the aromatics, it
appears that those with higher molecular weight are affected more than lower molecular weight
compunds. It is apparent that the effect of the dyer is different for different compounds and that some
compounds are very strongly affected.
As it can be seen from Table 1, the Nafion® dryer also lowered the TNMHC concentration by 10-
20%. While this may not be a large amount, it is significant, and since there are alternative methods to
jsing a dtyer, we recommend that an assessment be made of the effect of the dyer before it is employed
or analysis of speciated hydrocarbons in air.
INCLUSIONS
We have presented here some preliminary results on the assessment of the effects of a Nafion®
ryer on the non-methane hydrocarbons determined by a modified EPA Method TO-14 Based on these
ndings, we do not recommend the use of this or similar drying membranes for speciated hydrocarbon
etennination.
995
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REFERENCES
1. U.S. Environmental Protection Agency (1988). Method TO14: Determination of Volatile Organic
Compounds (VOCs) in Ambient Air Using Using SUMMA Polished Canister Sampling and Gas
Chromatographic (GC) Analysis In Compendium of Methods for the Determination of Toxic
Organic Compounds in Ambient Air. EPA/600/4-89/017. Office of Research and Development,
U.S. Environmental Protection Agency, Research Triangle Park, NC.
2. Cochran, J.W. (1987). Selective water removal in purge/GC analysis of volatile aromatics in aqueous
samples. J. High Res Chrom. 10, 573-575.
3. Coutant, R.W., and G.W. Keigley (1988). An alternative method for gas chromatographic
determination of volatile organic compounds in water. Anal. C.hem. 60, 2536-2537.
4. Pieil, J.D., K.D. Oliver and W.A. McClenny (1987). Enhanced performance of Nafion dryers in
removing water from air samples prior to gas chromatographic analysis. JAPCA 37, 244-248.
5. Pierson, W.R., AAV. Gertier, N.F. Robinson, J.C. Sagebiel, B. Zielinska, G.A. Bishop, D.H. Stedman,
R.B. Zweidinger and W.D. Ray (1994). Real-World Automotive Emissions—Summary of Studies
in the Fort McHenry and Tuscarora Mountain Tunnels. Submitted to Atmos. Environ.
6. Sagebiel, J.C., B. Zielinska, W.R Pierson, and AW Gertier (1994) Real-world emissions of organic
species from motor vehicles. Atmos. Environ., submitted
7. Zielinska, B., J. Sagebiel, G Harshfield, A.W. Gertier, and W.R. Pierson (1994). Volatile organic
compounds up to C20 range emitted from motor vehicles: Measurement methods. Atmos.
Environ., submitted.
996
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Table I. Results of analyses with and without the Nafion® dryer. Values are ppbC for each group and
total non-methand hydrocarbon (TNMHC)
Totals
Without
With
%Drop
EPLl
Paraffins
39.78
41,07
-3%
Oicfins
27,35
11.65
57%
Aromatics
27.4?
26.35
4%
TNMHC
94.6
79.07
16%
Other non-HC
88,03
36.23
59%
EPL2
Paraffins
1X1.04
160.12
12%
Olefins
51.57
33.53
35%
Aromaiics
137.75
121.06
12%
TNMHC
370.36
314.71
15%
Other non-HC
16.1.41
57.08
65%
EPL3
Paraffins
53.19
40.19
24%
Olefins
18.94
15.03
21%
Aromaiics
39.48
32.77
17%
TNMHC
111.61
87,99
21%
Oiher non-HC
124.43
48.19
61%
EPL4
Paraffins
212.51
196.07
8%
Olefins
66.28
49.55
25%
Aromatics
184.44
164.26
11%
TNMHC
463.23
409.88
12%
Other non-HC
137.57
48.46
65%
EPL5
Paraffins
149.32
134.57
10%
Olefins
38.91
25.55
34%
Aromatics
126.21
115.88
8%
TNMHC
314.44
276.00
12%
Other non-HC
62.56
34.97
44%
EPH1
Paraffins
54.36
43.94
19%
Olefins
13.60
11.06
19%
Aromatics
33.51
29.46
12%
TNMHC
101.47
84.46
17%
Other non-HC
62.5
16.48
74%
EPR9
Paraffins
324.53
173.68
46%
Olefins
97,47
43.63
55%
Aromatics
279.68
137.86
44%
TNMHC
701.68
375.17
47%
Other non-HC
186.00
25.67
86%
EPR10
Paraffins
109.23
79.34
27%
Olefins
32,84
17,48
47%
Aromatics
84.17
65.88
22%
TNMHC
226.24
162 70
28%
Other non-HC
60.36
18.59
69%
•JOTES:
% Drop ~ (without Nation® - with Nafion®)/Wilhout Nation®
"Other non-HC" category is a grouping of oxygenated, chlorinated and other compounds found in these samples.
Since these were not individually calibrated for, the results are relative only.
997
-------
Table 2. Effect of Nafiors dryer on selected compounds from EPL1. Note the significantly larger
drop for the olefins over the other groups.
Without
With
% Drop
Paraffins
Isopentane
4.28
4.37
-2%
2-MePentane
2.69
2.37
12%
n-Butane
2.42
2.33
4%
n-IIexane
2.38
2.13
11%
n-Pentane
2.08
1.91
8%
Olefins
2-Me-2-Butene
7.55
0.31
96%
2-Me-l-Pentene
3.94
0.81
79%
1 Butene+iButylcne
3.93
3.32
16%
4-Me-l-Pentcnc
1.65
1.69
-2%
1,3-Butadiene
1.52
1.20
21%
Cyclohexene
1.47
0.34
77%
t-2-Pentcne
0.47
0.35
26%
2-Me-l-Butcnc
0.37
0.20
46%
Aromatics
Benzene
4.63
4.38
5%
Toluene
7.56
6.83
10%
EtBenzene
1.07
0.99
7%
m/p-Xylene
4.07
3.93
3%
Styrene
0.80
0.74
8%
o-Xylene
2.25
2.04
9%
nPropBenzene
0.45
0.39
13%
998
-------
Statistical Distributions of Airborne PCB and Pesticide Concentrations
Measured at Regional Sites on the Great Lakes.
Donald F. Gatz, Clyde W. Sweet, Ilora Busu, and Karen S. Harlin.
Illinois Slate Water Survey
2204 Griffith Dr.
Champaign, Illinois 61820
ABSTRACT
The purpose of this paper is to report results of testing measured concentrations of total PCBs
and ten chlorinated pesticides in air and precipitation in the Great Lakes area for goodness-of-fit to
the lognormal distribution. Samples were collected at sites on Lakes Superior, Michigan, Erie, and
Ontario in 1991-1993. With very few exceptions, distributions of concentrations in the gas and
particle phases and in precipitation were not significantly different from lognormal.
INTRODUCTION
Concentrations of total PCBs and ten chlorinated pesticides have been measured in air and
precipitation over periods of 20-33 months at four regionally-representative locations in the bi-
national Integrated Atmospheric Deposition Network (IADN) on the Great Lakes. The purpose of the
measurements is to provide information needed to estimate atmospheric deposition of toxic materials
to the lakes. It is useful to know whether the measured concentrations conform to standard statistical
distributions, both to describe pollutant concentrations in air or in precipitation, as well as to guide
summarization and future uses of such data.
The lognormal distribution has frequently been found to describe the distribution of common
criteria air pollutants (1). However, relatively few measurements have been made of such non-criteria
pollutants as PCBs and chlorinated pesticides, and their dominant distributional model is not well
established.
The purpose of this paper is to report results of testing the observed distributions for goodness of
fit to the standard lognormal distribution.
METHODS
Sampling sites are shown in Figure 1. Data used in this paper were derived from samples
collected at sites located at Eagle Harbor, Michigan, on Lake Superior, at Sleeping Bear Dunes
National Lakeshore, on Lake Michigan; at Sturgeon Point on Lake Erie; and at Point Petre, Ontario,
on Lake Ontario. Canadian scientists also collect samples on Burnt Island in Lake Huron, but data
from that site are not examined here. Twenty-four hour samples of airborne particles and vapor were
:.oIlectcd at 12-day intervals on glass fiber filters and vapor traps of polyurethane foam (PUF) or
KAD-2 resin, using modified high volume samplers. Twenty-eight day precipitation samples were
;ollecied using wet-only samplers with stainless steel sampling surfaces and a heated enclosure
:ontaining an XAD-2 absorption column. The XAD and PUF sorbents and the glass fiber filters
vere Soxhlt-extracted for 24 hours with 1:1 hexane/acetone, concentrated by rotary evaporation, and
hen cleaned and fractionated by column chromatography with silica gel. Fractions eluting from the
999
-------
silica column were analyzed for 103 PCB congeners and ten pesticides using GC/ECD (2, 3).
logarithms of the measured concentrations in air and precipitation were tested for normality by the
IJlliefors variation of the nonparametric Kolmogorov-Smirnov test using SYSTAT statistical
software.
RESULTS
Results of the tests of goodness-of-fit to a lognormal distribution are given in Table 1. Very few
distributions were found to be statistically different from the lognormal distribution at the 1% or 5%
levels. In at least one case (gas-phase HCB al the Sleeping Bear site; see Figure 2), a single
questionable data point appears to have been the cause of the significant probability.
Figure. 2 shows distributions of four selected compounds plotted as blank-corrected
concentrations on a log,,, scale vs. percentile on a probability scale. Lognormally-distributed
concentrations will appear as a straight line on such a plot. The lowest concentrations shown may
have percentile values of 10-30%, or even higher. This was the result of blank subtraction reducing
the net concentrations of many samples to zero, which cannot be plotted on a log scale. These plots
also show the limit of detection (LOD), which is defined as the mean matrix-specific field blank
(over all sites) plus three standard deviations.
It is clear from the distribution plots that, consistent with the statistical goodness-of-fit tests, the
concentrations of most compounds display a close approximation to straight lines in the gas-phase,
the particle-phase, and in precipitation. The upper and lower tails of the distributions show occasional
deviations from straight lines. Upper-tail deviations may signal strong local sources, as in the case of
gamma-HCH (Lindane) at the Sleeping Bear site (Figure 2), where occasional use in local orchards is
suspected. Co-elution interferences are another possibility. Deviations at the lower tails are more
frequent, and are probably related to the vagaries of the blank correction procedure at low-
concentrations.
While a detailed comparison of concentrations between sites and between gas, particle, and
precipitation phases is beyond the scope of this paper, it is worthwhile to point out some obvious
features. For most of the compounds analyzed in this work, including those shown in Figure 2, gas-
phase concentrations exceed those of the particle phase, sometimes substantially. CJas-particIc
partitioning is known to be a function of the vapor pressure of the compound.
Variations in concentration between sampling sites are also apparent. Typically, the Sturgeon
Point (Lake Erie) and Point Petre (Lake Ontario) sites experience the higher concentrations. Some
compounds demonstrate, that they are well-mixed in the atmosphere by showing little variation
between sampling sites, particularly in the gas phase; HCB is a good example (Figure 2).
CONCLUSIONS
Gas-phase, particle-phase, and precipitation concentrations of field-blank-corrected total I'CBs
and the ten pesticides examined in this paper were found to be not statistically different from the
lognormal distribution in nearly every case at four Great Lakes sampling sites.
ACKNOWLEDGEMENTS
This paper would not have been possible without the diligent efforts of all those who collected
the samples in the field, sometimes under adverse conditions, and those who analyzed them in the
laboratory. Sherman Bauer provided timely computer help. This work was supported by the U.S.
Environmental Protection Agency (EPA), Great Lakes National Program Office, under Contract No.
GL995476-01-1.
1000
-------
DISCLAIMER
This paper has not been subjected to EPA policy review and should not be construed to represent
the policies of the agency. Mention of any product name does not constitute endorsement.
REFERENCES
1. Taylor, JA.; Jakeman, A.J.; Simpson, W.R. Atmos. Environ. 1986 20, 1781-1789.
2. Basu, I., Harlin, K.S., Sweet, C.W. AOAC International 107th Annual Meeting, July 1993,
Washington, D.C., Abstract #233.
3. Sweet, C.W., Basu, I., Harlin, K.S. "Toxic organics and trace metals in air and precipitation at
the U.S. IADN stations," in Proceedings of the 1993 Annual Meeting of the A&WMA,
Air & Waste Management Association, Pittsburgh, 1993; paper 93-RP-l37.03.
1001
-------
Table. 1. Probabilities given by the Lillicfors variantion of the nonpiirametric Kolmogorov-Smirnov lest
that concentrations of airborne toxic organic compounds are lognoraially-distributed. Values in bold
face indicate instances where the hypothesis may be rejected at the 1% significance level, or better,
based on a Bonferroni-adjusted critical probability of 0.01/44 --- 0.00023 for 44 comparisons. The
corresponding critical probability for 5% significance is 0.00114. Probabilities are not given for N<10.
a) Gas phase.
Compound
Eagle
N
Harbor
Prob
Pt. Petre
N Prob
Steeping Bear
N Prob
Sturgeon Pt. No. significant at:
N Prob 1% 5%
aloha- Cblorciane
gamma-Chlordane
DDD
DDE
DDT
Dieldrin
HCB
alptia-HCH
gamtr,a-HCH
trans-Nor.achlor
Total PCBs
34
34
49
72
52
74
73
84
84
34
78
0.38745
0.17086
0.07481
0.044S0
0.30595
0.77336
1.00000
1.00000
0.00648
0.10899
0.17912
33 0.67741
33 0.54109
49 0.80145
59 0.76009
67 0.19071
72 0.21752
60 0.00136
80 0.99444
80 0.05912
32 0.80774
78 0.01352
37
37
46
54
54
56
55
57
56
36
55
0.13609
0.00309
0.47444
0.394C6
0.36634
0.54467
0.00000
0.34531
0.00046
0.17317
0.06992
38 0.56710 0
38 0.90097 0
51 0.28694 0
52 0.93G99 0
54 0.21648 0
18 0.10328 0
51 0.24681 1
59 0.18584 0
59 0.00434 0
38 0.33968 0
54 0.93863 0
Totals 1
b) Particle phase.
Eagle Harbor Pt. Petre Sleeping Bear Sturgeon Pt. No. significant at:
Compound
N
Prob
N
Prob
N
Prob
N
Prob
1%
5%
alpha-Chlordane
6
0.21111
5
—
5
7
...
0
0
gamma-Chlordane
18
0.00022
13
0.34872
12
0.43474
14
0.47063
1
1
DDD
11
1.00000
5
—
5
—
11
0.36180
0
0
DDE
22
0.20316
20
0.04092
16
0.30222
17
0.83685
0
0
DDT
19
0.80166
25
0.55681
11
0.95210
17
0.10187
0
0
Dieldrin
14
0.57388
14
0.48382
13
1.00000
12
1.00000
0
0
HCB
24
0.00751
18
0.16842
14
0.82408
17
0.22970
0
0
alpha-HCH
18
1.00000
14
0.82046
10
0.06632
10
0.47319
0
0
gamma-HCH
19
0.76274
21
0.33913
11
1.00000
14
0.18308
0
0
trans-Nonachlor
20
0.91907
12
0.98615
10
1.00000
12
1.00000
0
0
Total PCBs
26
0.00740
25
0.63075
13
0.07375
17
0.92447
0
0
Totals
1
1
c) Precipitation.
Compound
Eagle
N
Harbor
Prob
Pt. Petre
N Prob
Sleeping Bear
N Prob
Sturgeon Pt. No. significant at:
N Prob 1% 5%
alpha-Chlordane
gamma Chlordane
DDD
DDE
DDT
Dieldrin
HCB
alpha-HCH
gamma-HCH
trarvsNonachlor
Total PCBs
17
17
5
28
19
29
32
28
27
14
37
0.51924
0.28085
0.32772
0.47176
1.00000
0.93477
0.24376
0.69745
0.89574
1.00000
14 0.62704
8
26 0.24768
23 0.12388
28 0.58466
28 0.57274
30 0.24458
27 0.98416
13 0.18950
32 0.59908
12
15
6
17
20
18
22
18
17
12
22
1.00000
0.72697
0.07842
1.00000
0.52451
0.52539
0.19583
0.14638
0.86128
0.21214
16 0.09071
10 0.88316
25 1.00000
20 0.99457
24 0.58326
24 0.01840
22 0.53775
18 0.88656
10 0.22915
25 0.71791
Totals
1002
-------
i | Masier S^tion
^Eurnl JsfanC
wc v;B
\J
Figure 1. 1ADN sampling site locations.
1003
-------
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Stability of Reduced Sulphur Compounds
in Whole Air Samplers
Quang Tran and You-Zhi Tang
BOVAR CONCORD Environmental
2 Tippcit Road
Toronto, Ontario, Canada, M31I 2V2
ABSTRACT
Reduced sulphur compounds can cause odour nuisance problems associated with kn'ft mill
and sewage treatment operations. Accurate and reliable determination of reduced sulphur
compounds is often required, but ir is a challenging task due to the reactivity of reduced sulphur
species and consequent difficulties in collection and storage of air samples. Several whole air
samplers were evaluated for storage of reduced sulphur compounds at concentrations of 100 ppb
(Tedlar bag only), 1 ppm and 10!) ppm. Severe losses of 11-2S and mercaptans were found in
samples collected in electro-polished stainless steel canisters, although these canisters have been
proven suitable for many volatile organic compounds. The losses of more volatile species were
less severe than less volatile ones in Teflon vials, and glass and silanized glass bottles with
Teflon-lined septum caps. In general, COS, (?S2, CH^SCH,, and OI^SSOH., were more stable
than II2S and mercaptans, and the reduced sulphur compounds were more stable in the Tedlar
bag than in other sample containers.
INTRODUCTION
Reduced sulphur compounds are important constituents in the sulphur cycle between
hydrosphere, lithosphcrc, biosphere ar.d atmosphere.1 Certain reduced sulphur compounds, such
as hydrogen sulphide (I I2S), methyl mercaptan (Cl-I-jSH or MeSH) and ethyl mercaptan (C2H«SH
or EtSH), dimethyl sulphide (CH-,SCH3 or DMS) and dimethyl disulphide (CH3SSCH3 or
DMDS), can cause odour nuisance problems normally associated with emissions from kraft mill
and sewage treatment operations." Therefore, measurements of reduced sulphur compounds in
air are necessary for studies on sulphur chemistry and the environment, and are specifically
required for certain cases of air quality assessments.3 However, accurate, and reliable
determination of reduced sulphur compounds is a challenging task, mainly due to the reactivity
of reduced sulphur species and consequent difficulties in collection a/id storage of air samples
containing these compounds.
A number of analytical methods (references 2, 3 and as cited in reference 4) have been
applied for determination of reduced sulphur compounds in air. On-site direct measurement
provides the most reliable results, and is suitable for process monitoring. However, the method
is limited by field conditions and requirement for skilled field personnel capable of operating the
on-site analyzers. It is also expensive or not feasible for large scale environmental studies,
especially those conducted in remote areas or requiring simultaneous multi-location monitoring.
Field sampling followed by laboratory analysis of samples collected from different sites affords
the possibility of a full scale environmental impact assessment, but may suffer from poorer data
quality caused by degradation of instable sulphur species during sample storage.
1005
-------
Several whole air samplers were evaluated for storage of reduced sulplmr compounds at
concentrations of 1(X) ppm, 1 ppm and 1(X) ppb in air. Initial test results arc reported in this
paper.
EXPERIMENTAL SECTION
Supplies and Instrumentation
Sample Containers. The whole air samplers evaluated included 10-LTedlar® bags (with
stainless steel inlet and septum ports) from SKC Inc., Eighty Four, PA (referred as Tedlar bag),
2.8-L Summa® canisters from Scientific Instrumentation Specialists, Moscow, ID (SIS canister),
a 1.7-L elcctro-pollshed canister from KBU Environmental Technologies Inc., Hamilton, ON
(KBU canister), and 0.85-L electro-polished canisters from Biospherics Research Corp., Hillsboro,
OR (BRC canister). Other containers, including 30 mL Teflon vials (Oak Ridge FEP Centrifuge
tubes, Nalge Company, Rochester, NY) with ETFE (Tefzel, i.e. ethylene-tetrafluoroethylene)
scaling cap assembly, and 60-mL (2 oz) amber screw cap glass bottles with Tcflon-lincd septa
(Supelco, Ir.c., Bellefonte. PA), were also tested. Some glass bottles were used without further
treatment while others were deactivated with Supelco Sylon-CT solution (5%
dimethyldiehlorosilane in toluene). All sample containers had never been used.
Chemicals niul gases. The reduced sulphur gas standards were prepared from a gas
mixture (101 ±2 ppm H2S, i06±2 ppm COS, 104±2 ppm MeSH, 84.0x1.7 ppni EtSH, and 110±2
ppm CS, in N-,) from Maiheson Gas Products Canada, Whitby, ON, and DMS (99-t%) and
DMDS (99%), both from Aldrich Chemical Company, Inc., Milwaukee. WI. Ultra high purity
helium used as the carrier gas, ' zero gas" hydrogen and air used for the flame photometric
detector (FPD), raid the ultra dry air used for preparation of gas standards, were all from linde
Division, Union Carbide Canada Limited, Toronto, ON.
Analytical Instrumentation. An Hewlett Packard (Palo Alto, CA) HP5890 Gas
Chrorr.utograph (GC) equipped with an FPD and a 75 m x 0.53 mm x 3.0 pm D1S-624 column
(J&W Scientific, Folsom. CA) and an HP5890 Series II Plus GC equipped with an I IP 5972 mass
selective detector (MSD) and a 60 m x 0.32 mm x 1.8 pm DB-624 column were used for sample
analysis. Gas samples were, injected with a Hamilton #1725 (0.25-ml.) gastight syringe (Reno,
NE'j. Complete GC resolution of the 7 test compounds was achieved with a temperature program
as follows: 40X for 1 min, 5°C/inin to 80°C and 25"'C/min to 200°C. The helium flow rates for
the megaboie and capillary columns were ca. 10 mL/tnin and 1 niL/min, respectively. The
chrornatograms obtained with the GC/MSD and GC/FPD are shown in Figure i.
Procedures
All sample containers, with the exception of the Tedlar bags, were evacuated to -100 kPa
with a vacuum pump (PN. 7411-70, Canadawide Scientific Ltd.. Toronto, ON). New canisters
came from manufacturers/suppliers under vacuum and were evacuated again in our laboratory
without other treatment procedures. Previous experience in our laboratory indicated that
conditioning of canisters with moisturized air resulted in severe losses of H,S and mcTcaptans.
After thorough flushing of the regulator, the 100-ppm gas standard (H2S, COS, MeSI I, litSIi and
CS;; was used to fill ?. Tedlar hag spiked with 3 pi. of DMS and 3.7 ul- of DMDS to prepare
a standard containing the 7 sulphur compounds at ca. 100 ppm. One SIS canister was filled with
the gas standard from the 100 ppm Tedlar bag to atmospheric pressure, and slightly pressurized
by adding 500 mL of the same gas standard to the canister using a 50-mL gas tight glass syringe
(B-D Multifit). One Teflon vial was filled with 60 mL of the 100-ppm bag standard.
1006
-------
Appropriate volumes of the KK)-ppm hag standard were injected into other sample
containers, which were then filled with air to prepare gas standards at ca. 1 ppm. The canisters
(SIS, KBU, and BRC) were filled with air lo 20 psi; die glass bottle, sihu:i/.cd gluss bottle. and
Teflon vial were filled with air to double volumes of their nominal capacities; the Tedlar bag was
filled to volume (10 L). A 100-ppb standard in the Tedlar bag was prepared with proper dilution
of the 100-ppm Tedlar bag standard
The g;is standards were analyzed within 15 minutes of preparation and during the
following days us:ng the GC/FPD antlGC/MSD. The analytical relative standard deviations were
15% and 10% for the GC/FPD and GC./MSD, respectively. To access the sample stability, the
analytical results of the 1-ppm and 100-ppm samples were compared, respectively, with the
results of the 1-ppm ar.d 100-ppm Tedlar bag standards, whose initial values jpon preparation
were assigned as 100 in Tables I, 2 and 3.
RESULTS AND DISCUSSION
Non-Conventional Sample Containers
The silanized or nor,-silanized glass bottles and Teflon vials used in this study were not
containers regularly used for air sampling. They were made of different materials and the
physical and chemical properties of their inner surfaces differed from those of the conventional
air samplers. They were therefore tested for comparison with the commonly used air sample
containers. Compared to canisters whose metal inner surfaces, though deactivated, might act as
a catalyst for the reactive reduced sulphur species, the glass and Teflon surfaces might provide
the possibility of reducing sample losses during storage. However, the test results did not suggest
apparent advantages of using tiiese containers for sampling reduced sulphur compounds in air.
In general, the lo»scs of H0.S and COS were less severe than the other 5 compounds in
these ton-conventional sampler containers. Within 24 hours, the concentrations of MeSI 1, RtSlI,
DMS, CS? and DMDS in the glass bottle and Teflon vials were reduced to less than 25% of the
original values, with the exception of MeSH in the glass bottle. The silanized glass bottle was
better than the other three containers for MeSH, F.tSH and DMS. The magnitudes of decrease
were similar for samples at 1 ppm and 100 ppm levels in Teflon vials. Concentrations of MeSH,
EtSH, D.\1S. CS, and DMDS in all these containers further decreased with time, most to less
than i% after 12 days of storage (Table I). It appeared that the stability of the test compounds
were related to their volatility.
Canisters
The storage stabilities of reduced sulphur compounds in canisters were apparently
different and also varied with different canisters (Table 2). It was obvious that the stability of
the test compounds ir. canisters were more dependent on their reactivity rather than volatility.
SIS Canister. At 1 ppm level, at least 70% of H.;S, MeSH and EtSH vanished once
prepared in the SIS canister and the concentrations of these compounds further decreased with
time to less than 5%. No significant losses were observed for other four compounds. At 100
ppm, all 7 compounds were relatively stable.
BRC Canister. H2S, MeSH and EtSH practically disappeared upon introduction into the
BRC canisters. The concentrations of the other four compounds decreased with time.
KBU Canister. This sampler appeared to be even worse than the BRC canister. In
addition to ll^S, MeSH and HtSH, DMS was also eliminated upon entering the canister.
1007
-------
Tedhir Any
li was observed that when reduced sulphur compounds at 100 ppb were prepared in the
biig, losses up to 30% occurred. By comparison with the COS response, it was certain that losses
ot 10% occurred for H2S when the 1-ppm bar. was prepared and it is why the. initial value for
H?S is listed as 90 in Table 3. The losses throughout the storage period of the 1-ppm bag were
not significant for most compounds. The storage losses of the less volatile compounds were
slightly greater than the more volatile ones (except H2S), suggesting the losses were likely due
to .surface adsorption. This was similar to the observation with glass bottles and Teflon vials.
Losses of the 100-ppb sample were 5% to 40% more seveTe than the 1-ppm one, while the losses
of 100-ppni sampie were not obvious during the test period.
CONCLUSIONS
Although the Ted'nr bag also suffered from sample losses, it was the most favourable
device fo: whole air sampling of reduced sulphur compounds.
KLIL'ULNCL.S
1. Lovelock, J.F,.; Maggs, R.J.; Rasmussen, R.A. Nature 1972 237, 452-453.
2. Oshr, K; Duncan, D.W. Pulp & Paper Canada 1978 79(12). T340-T342.
3. Odor Threshold for Chemical with Established Occupational Health Standards, American
industrial Hygiene Association, Akron, ON, 1989.
4. Kelly, T.J.; Gaffnsy, J.S.; Phillips, M.F. Tanner, R.L. Anal. Chem. 1983 55, 138-140.
Table I. Stabilities of reduced sulphur compounds in non-conventional air samplers
JUS
COS
MeSH
EtSH
DMS
cs2
DMDS
SiUmi'/.cd pluss (I ppm)
Within 15 minutes
107
87
97
90
101
110
93
1 day
91
93
95
93
54
30
5
2 days
90
100
90
83
30
15
1
12 days
30
50
10
<1
<1
<1
<1
Glass bottle (1 ppai)
Within 15 minutes
91
110
106
78
87
79
91
1 day
95
89
70
25
24
20
1
2 days
85
84
50
17
14
7
<1
12 days
20
30
<1
<1
<1
<1
<1
Tcilon vial (1 ppm)
Within 15 minuws
96
79
90
87
77
109
67
1 day
73
56
15
15
8
2
5
2 days
60
43
6
5
3
1
1
12 days
1
I..A
o
6
3
<1
<1
<1
<1
Tef.ar vir.l (100 p;in)
within 15 mir.uus
111
91
104
103
91
87
93
1 day
77
72
16
16
10
12
10
2 days
67
54
13
12
13
5
5
12 tlavs
50
6
<1
<1
<1
<1
<1
1008
-------
'['able 2. Stabilities of reduced sulphur compounds in canisters
H,,S
COS
MeSH EtSH
DMS
SIS canister (100 ppm}
HMDS
Wilhin 15 minutes
95
107
99
93
103
89
92
1 clay
96
85
87
89
84
84
83
2 days
103
81
74
62
78
62
61
12 days
98
78
64
68
71
77
84
SIS canister (1 ppm)
Wilhin 15 minutes
28
95
30
30
97
93
102
1 day
17
86
23
15
105
95
97
2 days
2
76
6
7
125
111
121
12 days
<1
64
3
2
82
S5
87
BKC canister (1 ppm)
W:ihin 15 minutes
1-1
98
9
19
80
95
89
1 day
4
S6
3
7
81
82
icy
2 days
<1
67
1
2
83
82
88
12
-------
GC/FPD
7
L Hydrogen sulphide
2. Carbonyl sulphide 6
3. Methyl mercaptan
4. Ethyl mercaptao
5. Dimethyl sulphide |
6. Carbon disulphidc I'
7. Dimethyl disulphidc
)<
;i
Time
GC/MSD
Figure 1. GC/FPD and GC/MSD chromatograms of 7 reduced sulphur compounds
1010
-------
A New Vapor and Gas Test Atmosphere Generator
with Broad Concentration and Flow Output Capabilities
J.K. McGee, P A. Evansky, D Terrell, and L.C. Walsh
ManTech Environmental Technology Inc., P.O. Box 12313, Research Triangle Park, NC 27709
D.W. Davies and D.L. Casta
U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Abstract
IT is poster describes a dynamic flow vapor generate thai can produce v«por fes* atmcspftorcs of bo'h pure
compounds or fixtures with concentrations ranging from pats per billion (ppb) to percent, within the lirrHing
constraint cf the saturated vapor pressune(s). Test atmosphere fiow rates can be varied frorrr 2 Lymin to ever 100 U
min.Trie generator consols of h puri^-suppl^d .'iquM ev?jp:)mfor coij|)(f?I to a unique OLtnuf control st'oHon rhf?
oitfpjf control scctfc.'i allows e.Jhcr nil or u Irustk.'n cf the (jenorntor v.ipnr output !o he? mixed with ?;ie diluting a-'
suopiy. Metering of a fraction of tte generator vapor output Is accomplished with a mass f'ow controller thai reojfres
only 0.0S atm pressure lo actuate to :ts ful' sca.'e flow- With a simpi9 modification, the gcneratccan a'so prepare
gas lesf atmospheres.
Introduction
Laburnfonss thai ana'y/o ambient air directly or perform onvirormental chamber skidies nr-ed to fx? ,iWe to
prepare a w:de range of volatile crcjanic compound (VOC) atmospheres for calibration or lest. Multiple vapor
generation methods are frequently required.
Vapor Generation Methods
3 LarpvU Raff
{2 -»100 * I'mn)
o Efw^toCcrerr.c}
Primary Slantfs-d
CJ F;tmnfy Slr»ndQ*3
DisndvantagAS
u Ou- ntM °-cn^*\,
O Cannot Caic.bto M^ss Esta-cv
Corcvhafart
O Carry* "-cdusn &t* Ccrnot F'Cdu:o Steady CX*put
cl M-ftco"* potent VimjMc
1 Cr.-no? P.'cduro VUtco-po"*
VixlUtW3
10 tCO 1 10 100 tCCG t '0
ppb ppm percent
Concentration Range Produced,
at 5 L Minute/Air Flow Rate
1011
-------
We havu developed a simple, rn'.iafcle apparatus U> safely split the output of dynamic vapor generators, aid extend
the lowest stable output concentration by three orders of magnitude.
Although the uoparatus ck's:qn is gener;c, and able to t>e coupied to most vapor generator, first applications have
been with the "j-tube" liquid evaporator for use in inhalation exposure chambers.
Vapor Generation Methods
Diffusion Tube
Permeation Tube
t
-------
The generation system may be operated in Ihrot: '>.'i<1opcnck."it morios, io allow none, nM, or pari of the vapor
output to te directed to the chamber.
Mode #1, Bypass. No vapor flow to chamber
Bypass motle aHcws yrncntnr output tc ho n^'rkty rrHitfxl hiio and away fr>m !tn? onvltrnmenfaf chamber main arr flow It is used
during startup and shu^D-vr to keepcharr.bercc-tcentfa: o~ risf and %. curves as sharp as possible.
Output Row Control Section
TcEx-auet -y j
ScLfcU ¦
Mods #2, Total Flew. All vaocr llcw gees to chamber
Tbtal flow mode te used
-------
Mode #3. Spi t Pow. Part of vapor f'.ow goes to chamber.
Sp'H F'ow Is iciPij fo' VOC 1qp<3 of 5 ng/rnln > 5 nj.'T'.n to tho r.hfjT.hor olr supply (5 ncj/min into 5 Urrtn total gos flow gives
100-6C0 pals-per-^'ltort (ppb] tor most VOCs). Excess VOC tbw rate t very small (0 3 g'hrj and easily scrubbed using smal1
charcoal filler units.
Output Flow Contra! Section
V«!
MFC
Mess cto*
Trie cho'cs between opern'jng n Total Flow or Flow modes depends upon the liquid flow rate needed to
produce the desired cc*:entratlon. At fiow rates of less than 5mg/mln, uneven evaporation may lead to
oscii'ations in the measured vapcr concentrators, and operation In Total Flow mode may not be practical.
in this case, Ita Iky.iid f.ow fate and generator temperature should be increased to a level that gives an even
evaporation rate, a new generator concentration should be calcu'atcd, and the portion of the total generator
output reauired to give the desired chambe' concentration should be determined.
Alter ai inUil warn-up period In Bypass mode, Split Flow operation is begun, using the following steps;
• Close the Internal solenoid of the mass flow controller
• Adjust the mass flow controller setpoim to the desired setting.
• Open the output cortro1 sect:on needle valve fully.
• Tun the output cont'd section 3-way ba'l valve to direct the generator output to Sp'it Flow operation mode.
• Turn ttie generator ouput 3-way ball valve to direct vapor llow from Ihe Bypass mode to the Split Flow mode.
• Pressurize the generator to 0.05 atm pressure by adjustment of the needle valve
• Open the mass flow contro"er Internal solenoid valve to begin vapor flow to the environmental chamber.
T^ere are several advantages of splitting generator outout flow using a mass flow controller, es compared to
rotameters or other devices:
• Row rates are net affected by changes in supply gas temperalye and pressure.
• Precise, automated cortrcl of desired flow rate.
• Mass flew contrc'ler may be heated to 70 'C.
1014
-------
Very low head pressures arc required to ar.hisve full-scale flows, so vapor conrin*is&lfor> is not p. problem.
Percent Maximum Flow Rate Versus Supply Gas Head Pressure
lor TYLAN FC 280 Mass Flow Controllers
(all are unmodified stock, except 0-5 Umln #2)
100
90
c-o.oi 77
l/mlr / J
BO
0-5 l/mnl?
'modi'ted
7C
90
bO
30
20
10
0.
Supply Gas Head Pressure, Atm
By a simple modification of tfte output flov/ control section, gas test agents atmospheres can also be prepared;
Mode #4, Gas Metering. Compressed gas sources mnlerecf to cfcambsr.
Oytindens are plumbed to mass Ho# cortroMer -iet; the rema rde.'of the generation system Is unused h's operate mode.
Vapor Qenerator
Output Plow Control Section
..i
) 015
-------
Results and Discussion
• 1 here a*e currently \ 1 copies of tnis 5eroration system des'gn opening In 4 laboratories.
• Tha o'.dos* haft boon in serv'co sir.::c 1990.
• They have oeen used tc prepare test atmcsphe*es of 'he 'oHcwtng chem'cals:
¦ Vapor
• fi-Bnlnnol
• n Butyl Acetate
• Carbon Disulfide
• Chloro'orm
• Methanol
• Methyl f-Fkilyi Fthor
• Mx lures o' Dirrotby' S jccfrate. Dfmc^yl Glutamic, and Dimethyl Ad:pale
• f/fxtures o' Chlorc'orm and Trichloroethylene
• Toluene
• Tfichbroo'.hy!nn9
• m-Xylcne
¦ Gas
• Phosphlre
• Vapor concentrations prnduced ranguc from ppb tc percent, In chambers vary'ng in size from 1.7 to 422 L.
Conception output has oroven tc be stab'e and reliable in each mode of operation.
• For a!' studies. calculated concentrations were based 01 gravimetric calibrations o' generator and output corirol
section gas Hows, and either svot tost or dry gas melor caiibiattor. ct chamber air How rates.
• Measured concentrations were made w'th Indeperdertiy cai!brated infrared spectrophotometers or gas
chromatcgraphs.
• Agreement boUvnnn calculated and inr'asured c.oncontralirns was wilhh 10% for {>'r»cst evcy hjh; larger oners
were traced tn altered chanbe v'j flow re'i^s <-aus'jd by sbi'tcd orifice plat? colorations or chamber leaks.
Conclusions
• Generation system operation is simple and stralghtforwa-d in alt modes.
• Output flow contrci system is applicable to extending lowest stabie concentrations of oth9r dynamic generators.
• Srna"
-------
Air Monitoring at Alert in the High Arctic: Results of
One Year of Monitoring of Organochiorine Compounds and PAH
D. loom and L. Barrie
Atmospheric Environment Service
4905 Duffcrin Street
Downsview, Ontario M3H 5T4
P. Fellin and D. Dougherty
Concord Environmental
2 Tippet Road
Toronto, Ontario M3H 2V2
/). Muir, D. Grift, I., l.orkhart, and Ft. iUUick
Freshwater Institute
Dept. of Fisheries and Oceans
501 University Crescent
Winnipeg, Manitoba R3T 2N6
In January 1992, an air toxics sampler was set up at Alert, on Northern
Hllcsmcrc Island in the Canadian Arctic (82.5° N, 62.3" W) as part of an arctic air
toxics monitoring and assessment program. Since then, three more sites were added to
the network: Tagish, Yukon Territory near Whitehorse, Dunai Island in the former
Soviet Union, and Cape Dorset on Baffin Island. Organochlorincs (OCs) and PAHs
were sampled weekly to deteimine the types, concentrations and vapour-particle
relationships. High volume samplers with a 10 micrometre size selective inlet were
used with a collection cartridge consisting of glass fibre filter(s) for particulates
followed by two 20 cm diameter 5 cm thick polyurethane foam plugs for vapours,
with a weekly sample volume of approximately 11,000 m3. Samples were analyzed by
gas chromatography using electron capture detection and confirmation by GC/MS.
This paper will focus on selected compounds for 1992 at Alert: a volatile OC
hcxachlorobenzene, a semi-volatile OC DDT, and the PAIIs pyrene, benzo(e) and
benzo(a) pyrene. We will present annual average concentrations as well as weekly
integrated values to look for potential seasonal variation through temporal profiles and
their distribution between the particle and gas phases.
101?
-------
Laboratory Preparation of DNPH Derivatives of Carbonyl Compounds on
Sep-Pak™ Cartridges for Quality Assurance Purposes
R1ta M. Narrell
ManTech Environmental Technology Incorporated
P.O. Box 12313, 2 Triangle Drive
Research Triangle Park, NC 27709
ABSTRACT
Aldehydes and ketones are receiving increased attention both as
hazardous substances and as pronot.ers in the photochemical formation of
ozone in the atmosphere (1). They enter the atmosphere in the exhaust
of motor vehicles and other equipment using hydrocarbon and alcohol
fuels. Formaldehyde, the most prevalent aldehyde, is widely used as a
preservative, a textile treatment agent, and an intermediate in the
manufacture of urea formaldehyde and phenol-formaldehyde resins. Figure
1 (1,2) shows fornaldehyde concentration ranges for several types of
environments. Waters Sep-Pak* BNPH-Silica cartridges are convenient,
reproducible sanpling devices for quantifying aldehydes and ketones in
gases, including air. These cartridges trap the compounds by reacting
their with the DNPH, 2,4 Dinitrophenylhydrazine, on the cartridge (see
Figure 2) to form stable hydrazone derivatives. Derivatives are later
elutcd and analyzed by HPLC. Cartridges spiked in the laboratory are
used for quality assurance and instrument performance verification.
INTRODUCTION
Our laboratory prepares derivatized carbonyl compounds on Sep-Pak*
DNPH-Silica cartridges at requestor specified concentrations and
combinations for a variety of projects. This is accomplished by direct
application of aliquots of stock solutions onto the cartridges. Levels
are usually no greater than 75" of the DNPH loading on the cartridge
and are within established limits (3,4,5). Procedures for spiking
cartridges and preliminary analyses results are summarized in this
report.
EXPERIMENTAL
The solutions used to spike cartridges are quantitatively prepared
by a successive dilution technique using acetonitrile and 100 ml
voluTptric flasks. Using a syringe needle, both polyethylene filters
(See Figure 3) in the cartridge are pierced and calculated volumes of
these solutions, in microliters, are then injected onto the top of the
DNPri-Silica bed. I'he DhPH-carbonyl derivatives are eluted using
acetonitrile and the extracts analyzed by HPLC.
RESULTS
Figure 4 compares micrograms spiked for formaldehyde, acetaldehyde,
and acetcre to the concentrations found when a group of the cartridges
were extracted and analyzed, froir. this graph the relationship appears
to be linear for the 3 compounds examined. As more data becomes
1018
-------
available more extensive curve fitting may be carried out. figure 5
shows a graphic representation of the % difference between spiked
concentrations and HP1.C analysis values for each cartridge. With the
exception of acetone, the majority of of the values fall within our
current control limits of if- 25 %.
Contamination due to unintentional exposure of cartridges to
aldehyde and ketone sources can be a problem. Laboratory air often
holds high concentrations of acetone, in particular. This problem may
be alleviated by removing acetone sources from the spiking area and/or
modifying overall usage of acetone in the laboratory when cartridges
are being spiked. If not properly cleaned, glassware and syringes hold
the potential for contamination. Labeling inks, adhesives, and
packaging containers are also possible sources of contamination. In
some instances, acetonitrile may contain traces of aldehydes and
ketones, especially acetone. 10ug/l. of an aldehyde or ketone in
acetonitrile adds 0.1 ug ON'PH derivative per cartridge to background
values. If it is unacceptable for a particular application, the
supplier should bo contacted and/or- the acetonitrile purified (6).
Figure 5 shows micrograms found but not spiked for a group of
cartridges.
ACKNOWLEDGMENTS
The author acknowledges all those persons involved in the
independent analyses of the cartridges whose data was used in this
report.
REFERENCES
1. Committee on Aldehydes, Board of Toxicology and Environmental
Hazards, National Council, Formaldehyde and Other Aldehydes-,
National Academy Press, Washington, DC, 1981.
2. Tejada, S.B. " Evaluation of Silica Gel Cartridges Coated In Situ
With Acidified 2,4• Dirntrophenylhydrazine for Sampling of Aldehydes
and Ketones In Air", Intern. J. t'nviron. Chem. 1986, 26, 167-185.
3. Waters Scp-Pak" DNPH-Silica Cartridge, Care and Use Manual,
Millipore Corporation, Waters Chromatography Division: Mil ford, MA:
1992.
4. Wirberry, W.T. Jr, N.T. Murphy, and R.M. Riggan. "Method T0-1I" 1n
Compendium of Methods for the Determination of Toxic Organics in
Ambient Air. EPA/600/4-89/017, U.S. Environmental Protection
Agency, Research Triangle Park, NC. 1988.
5. Riggin, R.K. . Technical Assistance Document For Sampling and
Analysis of Toxic Organic Compounds in Ambient Air. EPA-600/4-84-
C41, U.S. Environmental Protection Agency, Research Triangle Park,
NC, 1984.
6. ASTM Method E111; Standard Test Method for Trace Quantities of
Carbonyl Compounds with 2,4-Diniirophenylhydra/ine.
1010
-------
Residential
Indoor Air
Contaminated
Workplace Air
Rural
Outdoor
Air
¦ Urban
Outdoor Air
Diluted Auto
Exhaust
Emissions
| J—iiiii rij~~— 1—it rifq—"*—'l ' i—r-rrrrrj 1—t—t iit iij 1—!—i twit)
10
100 1000 10000
Figure 1. Ranges of Formaldehyde Concentrations, PPBV.
NH,
Carbony4. Compound
HK'
HO,
[HI
,KO,
>
NO,
214-ElnUmi->bory|hyrira*,'ie
(DNPH)
NO,
OHPH Dorival'.va
(a hydraTnno}
-t-
Figure 2. Oerivatization Equation.
1020
-------
Lusr connector —-
— DNPH-Sifica
L»or
<4 connecter
Figure 3. Cutwav Vierf cf Sep-Plk* OE'H-Stnea Cartridges
ft
z
0
%
Formaldehyde, Acetaldehyde., Acetone
10. e
s.er
i
e.e-
i
?.e-
i
6.fit
j
5.IU
l
4.Or
3.0 [¦
2 ,0 ••
t.ei
!
y.eU
-
-1.0
o i
4 a
0
i—r1:
.t.B 3.0 S.0 7.0 9.H
8.0 2.a 4.a s.b s.a 10.0
MICROGRAMS SPIKED
FORWII.BEHVBE •- rtClrrtLBEHTOE -•0-- ACETONE
figure 4. Ce«f>*Wson of Hitrsgram Spiked to H-.crugr,imi Famd in HPIC Analysis of Cartridge Extracts.
1021
-------
1S3.B
148.0 -
130.0
1
110.8
lee.y
9e.b
8b.0
ve .o
EsB ,H
56.6
4b. 0
38 ,B
ZE.0
18.8
B .8
-la.e
Formaldehydej Acetaldehyde, Acetone
c c
x°x x
0 x x iv xx
X. — r.. 3 Xw _
Vxf3- ^ x ?• Ig/
„XDy x U 0 X X'X
* X_ „ X X
-2fl.fi "r ^ fi
-23.0 1 'JO ~ X '
-ia.e t
-50.8 ' - - - -1 i - — -¦ - - i- - - - - -J. -
0.0 18.8 2a.a 38.13 40.9 58.0 63.a
CARTRIDGE NUMBER
—X— FOTmAI.BfHVDF. — 0— ACETrtLDEHVSr. ftCKTOHF
5. % Differences Between
Calculated Spiked Concentrations and Analysis Valyes.
Forma 1dehyde , Aceta1dehyde, Acetone
l.S-
' 1 ¦
CARTRIDGE NUMBER
FOBMALBRHDE ACfTAOEHVDS ¦¦¦<>¦- ACETONE
Figure C. Micrograms Found but no'. Spiked.
1022
-------
Experimental Studies of an Ethanol-Air Flow Subjected to UV Light
Timothy A. Spaedv.r
Applied Research Laboratory
The Pennsylvania State University
P.O. Box 30
State College, PA 16804
The photolytic destruction of cthanol in air streams illuminated vvilh high
purity quartz low-pressure mercury lamps was investigated. A gas tight composite 316
stainless steel and acrylic reactor loop was constructed which allowed for doping
ambient air with cthanol, and circulating it past the lamps. Lthanol concentration
measurements were recorded when only one 40 watt lamp was illuminated, and again
when three 40 watt lamps were illuminated. It was determined that by increasing the
aclinic flux from 40 watts to 120 watts the overall rate constant for ethanol inciea.sed
from 8.25E-5 s'1 to 1.06E-3 s'1 when corrected for wall loss. Organic chemical
intermediates were formed by this process, and depended upon the actinic flux and the
residence time in the reactor loop. Finally, it was determined the 7.2mW/CFM of 185
nm radiation increased the kinetic rate constant by over two orders of magnitude.
1023
-------
Determination of Test Methods for Interior Architectural Coatings
Donald A. Whiiaker, l-inda S. Sheldon, and Jeffrey T. Keever
Reseaich Triangle Institute
Reseaich Triangle Park, NC 27709
A'iren L Nagdxi
ICf Incorporated
Fairfax, VA 22(B)
Pauline Johnston
Office of Air and Radiation
U.S. EPA
Washington, L)C 20460
Numerous building and consumer products used in indoor environments emit
VOCs. The U.S. EPA has undertaken a project to analyze VOC emissions from
various types of indoor products to determine which types of products result in
the greatest overall exposures to pollutants indoors. Critical 10 this project are
appropriate techniques to evaluate emissions of total and specific VOCs from these
sources. During 1992, the Research Triangle Institute (RTI) evaluated seven methods
for determining the VOC emissions from interior architectural coatings - specifically
interior alkyd and latex paints. Current work has involved a more detailed evaluation
of three of the seven methods with the final result being the development of lest
methods for the determination of volatile and scmi-volatilc organic compounds and
aldehydes from interior latex and alkyd paints.
The methods evaluated during this study were bulk product analysis by direct
injection onto a GC'MS, emissions testing using 52 L small stainless steel chambers
and ASTM standard methods for total volatiles and water content. Twelve interior
paints made by two major paint manufacturers were chosen for testing. The paints
represented three floss types (liar, semi-gloss, and gloss) and six color groups. This
paper discusses the analytical test methods and results.
Although the research described was funded by the U.S. EPA (Contract No.
6&-D2-0131). it has not been subjected to the required peer review and does not
necessarily reflect the views of the Agency and no official endorsement should be
inferred.
1024
-------
An Improved DNPH Cartridge Aldehyde Sampler
for 3-Dav Unattended Sampling
D.I1. Carclin and F..A. Gulvuilian
Entcch Laboratory Automation
950 Enchanted Way #101
Simi Valley. CA 93065
Title I of the 1990 Clean Air Act Amendment requires monitoring of all
compounds suspected of contributing to ozone formation in urban atmospheres.
Included in the list of suspected agent.'! arc aldehydes and ketones, with formaldehyde
being of particular interest due to its toxicity and normally higher concentrations.
Monitoring of the aldehydes and ketones during high ozone periods will be performed
by collecting eight 3-hour samples daily, seven days a week using samplers operating
unattended. The aldehydes and ketones will be sampled by passing ambient air
through Dinitrophenylhydrazinc (DNPH) cartridges allowing later recovery and
analysis in a laboratory.
A new aldchydc/kctone sampler is presented that conforms to the requirements
and QA/QC set forth by Federal, State, and Local monitoring agencies. The
32-position sampler allows up to 4 days of unattended sampling if spikes and
duplicates arc not utilized. To improve OA, 3-days of sampling can be scheduled
allowing one duplicate and one spike to be obtained every 24 hours in addition to Che
eight ambient air samples. Two sampler positions left unused cari them be analyzed
as field blanks. To provide for the simultaneous collection of samples and spikes or
duplicates, two 2000 seem electron mass How controllers are used to control the 1
l/min required flow rates. An onboard microcomputer both controls the MFC's and
records their actual flow rates for later downloading to a Windows based software
package for reporting. Programming and data retrieval can be performed using a local
PC system running under Windows"'1 or by a remote system using a modem.
Provisions are made for continuously adding a surrogate standard for added quality
assurance for both field sampling and laboratory extraction and analysis. An ozone
scrubber is utilized which reduces sample losses on the cartridge due to oxidation of
the carbonyl-DKPH complex. Default sampling protocols are provided, although a
llcxible Windows based editor allows considerable user modification to the sample
collection scheme. Field data and software will be presented showing precision and
practical advantages.
1025
-------
Intentionally Blank Page
-------
SUBJECT INDEX
acetaldehyde, 94, 19(5*, 204*, 771
acetone, 94, 196% 204*. 771
acid,
aerosols, 65*, 66, 76*, 77*, 763,
769*
deposition, 390
dicarboxylic, 639*
formic, 770*
gas phase organic, 639*
monocarboxylic, 639*
Mountain Acid Deposition
Monitoring Program, 72
organic, 639*, 770*, 771, 781
acidic sui.jtc, 65*, 66
acidity,
cloud water, 372, 378
historical aerosol, 436*
acrylonitrile, 517
adsorbent bed concentration
enhancement, 55
adsorbent sampling, 598
adsorbent trapping, 974
adsorbent tubes, 615
Aerometric Information and Retrieval
System (AIRS), 129, 277
aerosol concentrations, 646
aerosol deposition velocities, 13
aerosol dispersion tool, 21
aerosol, historical acidity, 436*
aerosol neutralization, 77*
aerosol particles, 638*
aerosol profiles, 541
aerosol transport and diffusion model,
21
aerosols, 3K4, 390, 637*
acid, 65*. 66, 76*, 77", 763, 769*
combustion, 917*
secondary, 652*
volcanic, 396
aerospace operations, 319
air exchange rate, 791
air mass sectors, 372
air masses, 384
air monitoring, risk-based, 740
air stripper emissions, 326
air trajectory, 873
aircraft sampling, 13
airsheds, in New Hampshire, 646
albedo, cloud, 371*, 378
alcohols, 851*, 911*
aldehydes, 83*, 84, 94, 196*, 197*,
204*, 211, 470, 770*, 771. 804,
851*, 1018, 1025*
alkyd paints, 1024*
ambient air database, 277
ambient data, 177, 282*
ambient ozone, 418
ambient sampling, 149, 164, 173, 195*,
217, 425*, 60S, 699, 721*, 740,
910*, 919
ammonia, 517, 523
ammonium bisulfate, 583
analyzers, elemental, 339
anion exchange membrane, 910*
anthropogenic chlorine, 396
anthropogenic hydrocarbons, 684*
anthropogenic pollution, 378, 871*
anthropogenic source, 893
Appalachian Mountains, 459
Arctic air toxics monitoring and
assessment, 1017
area source emissions, 7
Arizona,
Mcadvicw, 76*
Phoenix, 739*
aromatic, compounds, 405, 576, 994
Atlanta ozone precursor study, 282*,
283, 853*
atomic emission detector, 598
atmospheric deposition, 21, 72
* Indicates abstract.
1027
-------
atmospheric dispersion models, 7
atmospheric simulation, 21
atmospheric stability, 1
Auburn Tower, 464, 470
audit,
limits. 477
materials, 489
procedures, 993*
auto-GC, 148% 149, 164, 187, 496,
723*
automated carbonyl sampling, 198
automated cloud collection system, 72
automated cryogenic system, 192*
automated gas chromatographic systems
(auto-GC), 723*
automated preconcentration system,
912*
automated sequential sampling, 198
back trajectory analysis, 372, 384, 873,
879
background interferences. 92*
background monitoring, 724, 871*.
872', 873, 879
badges, passive organic vapor, 723*
Baytown, Texas, 993*
benzene, 857, 893
bcnzo(n)anthraccnc, 984
ben7.o(a)pyrene, 857, 984
benzo(e)pyrene, 919
biogenic,
compounds, 686*
emissions, 454*, 847*, 851*
hydrocarbons, 684*, 851*
bisulfatc. 583
blood gases, 903*
boundary atmospheric layer, 872*
boundarv-laycr meteorological profilers,
262
Brazil, petrochemical facilities in, 517
breath matrix, 903*
buildings,
characterization, 817, 823*
healthy, 797
large, 810, 817, 823*
ventilation systems, 817
built-in preconcentrator, 720*
bus emissions, 640
calculating schemes, 865
calculations.
mass balance emission, 318
source test calculations, 362*
California,
Fresno, 296
Los Angeles free-radical study, 541
Canadian Research on Exposure
Assessment Modeling program, 762*
cancerous tumors, 857
canisters,
cleaning, 655*, 656, 694*, 696*
passivated, 615
sampling, 83*, 184*. 205, 211, 283,
326, 655*, 656, 664, 685*, 686*.
687, 695*, 696*, 752*, 847*,
904*, 912*, 973*, 994, 1005
SUMMA canisters, 655*, 664, 684*,
685*, 686*, 687, 694*, 695",
696*, 724. 752*, 777*, 904*.
973*, 994
surface deactivation, 904*
capillary GC, 624, 631*, 632*, 714,
720*. 994
carbon,
adsorption system, 326
elemental, 652*
organic, 339
carbon dioxide, 817, 850*. 903*
carbon monoxide, 523, 529, 756, 791,
849*, 853*
carbonaceous-based triple adsorbent
traps, 30, 55
carbonyl compounds, in industrialized
areas, 94
carbonyl sampler, 211
carbonyl sampling, 84, 198
carbonyls, 84, 92*, 93*. 94, 135, 195*,
197*, 198, 204*, 205, 211, 217, 470,
739*, 777*, 804, 851*, 898, 1018
vertical profiles of, 470
carpet residues, 832
* Indicates abstract.
1028
-------
cartridges,
2,4-dinitrophenyIhydrazine (DNP1I),
195*. 196*, 204*, 1018, 1025*
PUF, 915*
sequential air, 93*
silica, 195*, 196', 204*, 1018
sorbent sample, 823*
CASTNET, 72, 78*, 92*, 722*, 111"
catalyzed flame ionization detector
(CFID). 339
charcoal filtration, 804
charcoal tubes, 84
chemical mass balance (CMU) method,
282*. 283
chemiluminescence instrumentation,
229, 235*
chemiiumincscencc monitors, 405
Chesapeake Bay sites, 638', 929*
chlorine, anthropogenic, 396
chromatography,
gas (GQ, 29*, 30, 111, 119, 129,
148*, 149, 164, 186*, 187, 326,
315, 339, 348, 496, 517, 597, 598,
615, 624, 631*, 632*. 699, 714,
720*, 722*, 723*, 823*, 847*.
903*, 912*, 915*, 994, 1017
high-performance liquid (HPLC), 92*
chromium,
hexavalcnt, 78*
VI emissions, 319
chryscnc, 984
cigarette smoke, 887, 893, 898
citizen-based survey, 459
Clean Air Status and Trends Network
(CASTNET), 72, 78*, 92*, 722*,
111*
CASTNet Air Toxics Monitoring
Program (CATMP), 92*, 722*,
777*
cleaning,
canister, 655*, 656, 694*, 696*
effects on indoor air quality, 797
climate, regional change, 371*, 378,
390
closed cycle coolers, 128*
cloud albedo, 371*, 378
cloud characteristics, 371*
cloud collection, automated system, 72
cloud microstructurc, 378
cloud reflectivity, 390
cloud water acidity, 372, 378
cloud water deposition, 78*
cloud water ion concentration, 384
cloud water monitoring program, 78*
clotid water sampling program, in
CASTNET, 78*
cloud-climate feedback mechanisms,
371*
CMB method, 282*, 283
Coastal Oxidant Assessment for
Southeast Texas (COAST), 173,
631*, 632*, 714
cold trap dehydration, 912*
Cologne, Germany, 523
combustion,
aerosols, 917*
residential wood, 849*
sources, 348
temperature dependence, 916*
commercial instrumentation, 235*
compliance tests, 477
computer systems, 362*
Connecticut, Wallingford, 94
continuous air monitors, 740
control technology, maximum
achievable (MACT), 588, 720*, 951*
controlled desorption trap, 911*
converters,
NO, , 235*
photolytic, 228*
coolers, closed cycle, 128*
cooling, Peltier, 149, 187
cryogen, 149
cryogenic, automated system, 192*
cryogenlcss ozone precursor system,
185*
cryotrapping, 597*, 723*, 911*, 974
cylinder gases, multicomponent, 508
cylinders, small high-pressure. 489
cylindrical probes, 943
Czech Republic, pollution in, 984
* Indicates absiract.
1029
-------
data,
ambient, 177, 282*
censoring, 503
collection, effects of temperature,
563
handling analysis, 496
interpretation techniques, 306, 496
meteorological, 245
PAMS, 306
statistical evaluations, 503
upper air meteorological, 270, 274*
validation, 129
database.
ambient air, 277
PAMS, 277
dehydration, cold trap, 912*
denuder systems, 417*. 425*
glass honeycomb, 426
Harvard/EPA Annular Denuder
System (HEADS), 426
selective collection system, 425*
deposition,
acid, 390
aerosol velocities, 13
atmospheric, 21, 72
cloud water, 78*
dry, 637*
Mountain Acid Deposition
Monitoring Program, 72
derivatization, 598
dermal exposure, 832
desorption,
controlled, 911*
thermal, 30, 598, 615, 624, 631*,
632*, 823*, 982*
detection limits, 503
detection systems, lightweight-standoff
chemical agent, 535
dctcctOTS,
catalyzed flame ionization (CF1D),
339
electron capture, 598, 1017
flame ionization (FID), 119, 129,
186*, 699, 714, 847*, 994
oxygen-flame ionization (O-FID),
339
thermionic ionization (TID), 339
dicarboxylic acid, 639*
dicsel emissions, 640
diesel fuels, 949*
diffusion, 937
diffusion denuder, 417*
diffusion model,
aerosol, 21
radial, 917*
dilution,
dynamic, 502, 992*
static, 992*
2,4-dinitrophenylhy drazi nc (DN PH),
cartridges, 195*, 196*, 204*, 1018,
1025*
substrates, 197*
direct trace analysis, 614*
dislodgeable residue, 832
dispersion,
aerosol dispersion tool, 21,
Gaussian, 1
modeling, 7, 953
diurnal measurements, 296
diurnal patterns, 755*
diurnal variations, 646, 769*
DNPH,
cartridges, 195*, 196*, 204*, 1018,
1025*
substrates, 197*
dry deposition, 637*
dust,
house, 925*
indoor exposure, 797
dynamic dilution, 502, 992*
dynamic flow vapor generator, 1011
dynamic mass transfer models, 917*
ecosystems, high-elevation, 78*
eddy correlation method, 13
electrochemical measurement, of ozone,
416*
electrochemical sensors, 416*
electron capture detector, 598, 1017
elemental analyzer, 339
elemental carbon, 652*
elcvational variations, 646
emission calculation method, mass
balance, 319
emission detector, atomic. 598
* Indicates abstract.
1030
-------
emission inventory, 455*, 458*
emission preprocessor system, 458*
emission rate. VOCs, 1
emission suppression techniques, 951*
emission lesl inelhod, extractive, 588
emissions,
air stripper, 326
area source, 7
biogenic, 454*, 847", 851*
bus, 640
chromium VI, 319
diesel, 640
evaporative gasoline, 709
exhaust, 709. 756
fossil fuel, 390
fugitive, 363
highway mobile, 456*, 457"
link-based, 457*
metal, 950*
mobile, 456*, 457*
uncertainties, 442
enhanced ozone monitoring (1<()M)
regulations, 103, 111, 119, 205, 211,
306,
environmental tobacco smoke (ETS),
887, 893, 898
equation testing, 7,
equivalent sphere, 943
esters, 851*
ethanol, 1023*
ethers, 685*, 911*
Eulerian air quality model, 637*
evaporative gasoline emissions. 709
exchange, anion, 910*
exchange rate, air, 791
exhaled breath matrix, 903*
exhaust emissions, 709, 756
exposure,
dermal, 832
indoor dust, 797
personal, 416*, 417*. 437*, 984
extraction, supercritical fluid, 905
extractive emission test method, 588
extractive Fl'lK, 588
feedback mechanisms, cloud-climate,
371*
fcncelinc air monitoring, 363,
filter pack system, glass honeycomb
denuder, 426
filtered noise field ion trap mass
spectrometry, 614*
filtration, charcoal, 804
fixed monitoring stations, 756
flame ionization detector (FID), 119,
129, 186*, 699, 714, 847*, 994
catalyzed (CFID), 339
floor residues, vinyl, 832
foam, polyurethane, 838, 915*
forest plants, ozone injury to, 459
formaldehyde, 83*, 93*, 94, 1964,
197*, 204*, 211, 217, 437*, 770*.
771, 857, 1018. 1025*
formic acid, 770*
fossil fuel emissions, 390
Fourier transform infrared (FTIR)
spectrometry, 1, 508, 517, 523. 529,
563, 583, 588, 714
Fourier transform microwave
spectrometer (FTMS), 551, 562*
Fourier transform spectrometer (FTS),
535
frec-radical study, in Los Angeles, 541
Fresno, (California, 296
FTIR spectrometry, 1, 517, 523, 529,
563, 583, 588. 714
fuels,
diescl, 949*
fossil, 390
gasoline, 949*
reformulated. 949*
fugitive emissions, 363
gas chromatography (GQ, 29*, 43, 30.
Ill, 119, 129. 148*, 149, 164. 186*,
187, 326, 315, 339, 348, 496, 517,
597. 598, 615, 624, 631*, 632*. 699,
714, 720*, 722*, 723*. 823*, 847*,
903*, 912*. 915*, 994, 1017
gas cliromatography/mass spectrometry
(GC/MS), 30, 315, 348, 517, 597*,
720*, 722*, 823*, 847*, 903*, 912*,
915*, 1017
• Indicates anstraci.
1031
-------
gas phase organic acid, 639*
gas phase reactions- 770*, 781
gas transfer system, 489
gases,
blood, 903*
multicomponent cylinder, 508
organic pollutant gases, 576
protocol, 483, 508
trace analysis, 551
volatile organic, 149
gasoline, 949*
evaporative emissions, 709
Gaussian dispersion. 1
Gaussian model, 865
Germany,
Cologne, 523
industrial sites in, 523
glass honeycomb denuder,Tiller pack
system, 426
Grand Canyon, 76*
Great I-akcs, 929', 930*. 999
Great Waters program, 929", 930*
greenhouse warming, 390
ground-based meteorological systems,
" 254
ground-based remote profilers, 245
ground-based remote sensors, 270
hand press, 832
1 larvard/EPA Annular Denuder System
(HF.ADS), 426
health hazards, 94, 709, 781, 80-1, 857,
930% 950*
healthy buildings, 797
heavy metals, 871"
herbicides, 838
hexavalent chromium, 319
high-elevation ecosystems, 78*
high-performance liquid
cliromatography (HPLC), 92*
highway mobile emissions, 456*. 457*
highway performance monitoring
system, 457*
historical aerosol acidity, 436*
house dust, 925*
Houston, Texas, 164
Houston-Port Arthur. Texas. 173
HPLC, 92*
humidity, effects of, 973*
Hybrid Single-Particle Lagrangian
Integrated Trajectories (HY-SPLIT),
372
hydrocarbons, 148*, 149, 173, 185*,
576, 684*, 685', 714, 733, 804,
850*, 973*, 991*, 994
biogenic, 684", 851*
non-methane, 296
volatile. 148*, 283
1/M programs, 456"
impactors,
micro-orifice, 638*
virtual, 424"
indoor air pollutants, 437*. 770*, 771,
781, 791, 797, 810. 817, 824, 887,
893, 898, 982*, 983*, 1024*
indoor dust exposure, 797
industrial sites, 517, 755*, 951*
in Germany, 523
industrial wastewater sources. 951 *
indusliiali'/xd areas, caibonvl
compounds in, 94
inorganic particulates, 426
inspection and maintenance (l/M)
programs, 456*
instrument siting. 262
instrumentation,
chemiluminescence, 229, 235*
commercial, 235*
portable analytical, 29*. 30, 55,
surface meteorological, 245
instrumentation issues, NO,
measurements, 227*
interferences, 405. 425*
background, 92*
interlaboratory comparison. 173
inventory,
emission, 455*, 458*
ozone, 458*
ion concentration, cloud water, 384
ion trap mass spectrometer, 699
* Indicates snstrnct.
103?.
-------
ketones, 84, 94, 196', 204*, 685*. 771,
851*, 911*, 1018, 1025*
Lake Michigan, 13, 83*
Lake Michigan Oxidant Study, 83*
iargc-building characterization, 817.
823*
large-buildings study, 810
latex paint, 771, 1024*
Latvia, air pollution in, 967
Lewisite, 598
lidar systems, 541
lightweight-standoff chemical agent
detection system, 535
link-based emissions, 457*
liquid chromatography, high-
performance (HPLC), 92*
Los Angeles free-radical study, 541
low-level measurements, 503, 598,
614*, 615, 624, 721*, 905
MACr, 588, 720*, 951*
mass balance emission calculation
method, 319
mass spectrometry (MS), 30, 315, 348,
517, 597*, 614*, 615, 624, 714,
720*, 722*, 823*, 847*, 903*, 912*,
915*, 1017
mass spectroscopy, 30
mass transfer, dynamic models, 917*
maximum achievable control
technology (MACT), 588, 720*,
951*
Meadview, Arizona, 76*
measurement,
anomalies, 405, 425*,
diurnal, 296
low-level, 503, 598, 614*, 615. 624,
721*, 905
NO?, 227*
ozone, 993*
satellite, 396
membrane, anion exchange, 910*
mercaptan, 1005
metals,
emissions, 950*
heavy, 871*
meteorological data, 245
upper air, 270, 274*
meteorological monitoring
requirements, 245
meteorological remote sensing, 254
meteorological systems,
ground-based, 254
upper air, 245
methane, 523, 529
methanol, 331
method detection limits, 503
method validation program, 915*
methylene diphenyl diisocyanate
(MDI), 361*
Mexico City, 755*, 756
micro gas chromatograph, 55
micro-orifice impactors. 638*
microwave spectra, 551, 562*
military spectroscopic sensors, 535
mobile emissions, 456*, 457*
mobile profiling system, 541
mobile sources, 457*, 709, 756
MOBILF5 model, 283
MOBILE5a model, 456*
modeling,
dispersion, 7, 953
dynamic mass transfer, 917*
Hulerian air quality, 637*
exposure assessment program in
Canada, 762*
Gaussian, 865
photochemical grid, 277, 441*
radial diffusion model, 917*
receptor, 282*, 283
regional particulate model, 637*
screening models, 7
modem-operated gas chromatography,
43,
moisture,
distribution, 937
effects of humidity, 973*
soil, 943
molecular beam FTMS, 562*
molecular sieve, 84
* Indicates absiract.
1033
-------
monitoring,
background, 724, 871*, 872*, 873,
879
CASTNET ait toxics program, 92*,
722*, 777*
cloud water, 78*
enhanced ozone regulations, 103,
111, 119, 205, 211, 306
fencelinc air, 363
fixed stations, 756
highwav performance system
(HPMS), 457*
meteorological, 245
Mountain Acid Deposition
Monitoring Program, 72
network. 229,
noncryogenic continuous system,
192*
ozone, 103, 111, 119, 128*, 187,
192*, 205, 211. 306. 416*, 417*,
418, 437*, 442 464, 763
Photochemical Assessment
Monitoring Stations (PAMS), 103,
111, 119, 128*, 129, 135, 142,
196*, 197*. 211, 245, 254, 274',
277, 282*, 295*, 306, 733
remote, 43
risk-based air, 740
monitors,
chcmilumincsccncc, 405
continuous air, 740
saturation, 640
ultraviolet ozone, 405
monocarboxylic acid, 639*
Mount Mitchell, North Carolina, 371*,
372, 378, 384, 390
Mount Pinatubo, 396
Mount Washington, New Hampshire,
646
Mountain Acid Deposition Monitoring
Program, 72
mountain air pollution, 459
Mountains, Appalachian, 459
multi-canister/multi-curlridge sampler,
205
multicomponent cylinder gases, 508
multisorbent tubes, 982*
national parks, ambient ozone in, 418
neutralization, aerosol, 77*
New Hampshire airsheds, 646
nicotine, 893
nitrogen compounds, 227*, 235*, 871*
nitrogen oxides, 227*, 228*, 229, 236,
416*, 425*, 529, 576. 733, 770*,
781, 853*, 931, 993*
nitrogen, UHP, 991*
NO, soil flux, 236
nonattainment areas, ozone, 103, 111,
245, 277, 464, 733
noncryogenic continuous monitoring
system, 192*
non-methane hydrocarbons (NMHC),
296
non-mcthane organic compounds
(NMOC), 184*, 192*, 283, 339
non-polar YOCs, 614*, 615
non-urban environments, 227*
North Carolina, 236
Mount Mitchell, 371*, 372, 378, 384,
390
Raleigh, 470
Raleigh-Durham, 464
Urban Airshed Model, 441*, 442,
454*, 455*, 456*. 457*, 458*
NO, specialion, 425*
NO, converters, 235*
NO, measurements, instrumentation
issues, 227*
NO, total reactive nitrogen compounds,
227*, 235*
odor control, 953
odor incident sampler, 363
odor sampling, 953
odor sources, 953
olefins, 994
open-path FTIR, 1. 517. 523, 529, 563
organic acids, 639*, 770*, 771, 781
particulate phase, 639*, 781
organic carbon, 339
* Indicates abstract.
1034
-------
organic compounds, 917*
in (he workplace, 723*
non-methane, 184*, 192*, 283
semivolatile, 29*, 424*, 915*, 916*,
917*, 918*, 919, 925*
toial gaseous non-methane, 339
total iion-methanc, 184*. 192*, 283
organic gases, volatile, 149
organic pollutant gases. 576
organic vapor badges, passive, 723*
organics, oxygenated. 684*
organochlorines, 1017
oriented strand board sources, 361*
outdoor air NO, speciation, 425*
oxidants, 781
Lake Michigan Oxidant Study, 83*
oxygen-flume ionization detector
(O-FID), 339
oxygenated organics, 684*
oxygenates, unsaturated, 851*
ozonation, 804
o/ont,
ambient, 418
compounds, 770*, 771, 781, 871*
concentrations, 646, 762*
control, 103
electrochemical measurement of,
416*
formation, 1018
injury to forest plan's, 459
inventories, 458*
lidai, 541
measurements, 993*
monitoring, 103, 111, 119, 128*,
187, 192*, 205, 211, 306, 416*,
417*. 418, 437*, 442, 464,763
nonattainnient areas, 103, 111. 245,
277, 464, 733
photochemical, 1018
precursors, 128*. 142, 148*, 149,
164, 185*, 186*, 187, 192*, 205,
211, 229, 277, 282*. 283, 295*,
496, 631*, 632*, 739*, 853*
profiles, 541
reactive chemistry, 771
scrubbers, 197*, 405, 1025*
ultraviolet monitors, 405
variation, 872*
PAHs, 778", 871", 887, 918*, 919
925*, 984, 1017
paints,
alkyd, 1024*
latex, 771, 1024*
PAMS, 103, 111, 119, 128*, 129, 135,
142, 196*, 197*, 211, 245, 254,
274*, 277, 282*, 295*. 306, 733
paraffins, 994
particle mass concentration, 797
particles,
aerosol, 638*
particulate phase organic acids, 639*.
781
particulates,
inorganic, 426
regional model, 637*
passivaled canisters, 615
passive organic vapor badges, 723*
passive samplers, 418, 424*, 437*,
762*
patterns,
diurnal, 755*
spatial, 762*, 763
speciation, 296
temporal, 762*, 763
PCBs, 999
PCDDs, 915*, 916*
PCI)I s, 915*, 916*
Peltier cooling, 149, 187,
Pennsylvania,
Philadelphia, 639*, 640, 652*, 763.
769*
Pittsburgh, 66
Uniontovvn, 66
performance evaluation, 489
permeability, soil, 937, 943
peroxyacyl nitrates, 852*
personal exposure, 416*, 417*, 437*.
984
pesticides, 832, 838, 999
petrochemical facilities, 517
phenanthrene, 919
phenols, 857, 905, 910*
Philadelphia, Pennsylvania, 639*, 640,
652*, 763, 769*
Phoenix, Arizona, 739*
* indicates absrraci.
1035
-------
Photochemical Assessment Monitoring
Stations (I'AMS), 103, 111, 119,
128s, 129, 135, 142, 196*, 211,
245, 254, 274*, 282*, 295% 733
data uses, 306
database, 277
objectives, 277, 306
requirements, 197*
photochemical grid models. 277, 441*
photochemical ozone formation. 1018
photofiagmentalion/pholoionization
spectrometry, 931
photolysis-assisted pollution analysis,
576
photolytic converters, 228*
phthalates, 778*
pilot plant, waste isolation, 687, 724
Pittsburgh, Pennsylvania, 66
platform, real-time analytical, 598
PM? „ 652", 755*, 769*, 77S*, 838
PMU, 436*, 640, 652*, 755*, 769*,
778*
polar VOCs, 517, 551, 562*, 614*.
615, 685*. 771, 903*. 904*, 905,
910*. 911*, 912*, 992*, 994
polychlorinated bipbenyls (PCBs), 999
polychlorinated dibenz-o-p-dioxins
(PCDDs), 915*, 916*
polychlorinated dibenzofurans (I'CDFs),
915*, 916*
polycyclic aromatic hydrocarbons
(PAHs), 778*, 871*, 887, 918*, 919,
925*, 984, 1017
polyurelhanc foam, 838, 915*
portable analysis methods, 29*, 43,
portable analytical instrumentation, 29*,
30, 55,
portable environmental sample
concentrator, 55
portable gas chromatograph, 29*, 43,
55, 326
preconcentration. 119
automated system, 912*
built-in, 720*
precursors, ozone, 128*, 142, 148*,
149, 164, 185*, 186*, 187, 192*,
205, 211, 229, 277, 282*, 283, 295*,
496, 631*, 632*. 739*, 853*
preprocessor, emission system, 458*
principal component analysis. 384
probes, cylindrical, 943
profilers,
boundary-layer meteorological, 262
ground-based remote, 245
radar. 254, 262, 274*.
remote, 245
wind, 262, 274*
profiles,
aerosol, 541
mobile, 541
ozone, 541
roadway, 283
temporal, 1017
temporal allocation, 455*
vertical profiles of carbonyls, 470
programmable field sampler, 752*
protocol gases, 483, 508
PUF cartridges, 915*
quality assurance, 119, 135, 142, 149,
270, 458*, 477, 483, 489, 502, 529,
640, 739", 752*
quality control, 122*, 739*
quantitation limits, 503
radar profilers, 254, 262, 274*
radial diffusion model, 917*
Radio Acoustic Sounding Systems
(RASS), 254, 262, 274* '
radiocarbons, 849", 850*
radon, 817, 937
Raleigh. North Carolina, 470
Raleigh-Durham, North Carolina. 464
randomized minimization search
technique, 396
* Indicates abstract.
1036
-------
reactive nitrogen compounds (N0y),
227*, 235*
real-lime analytical platform, 598
receptor modeling, 282*, 2X3
reduced sulfur compounds. 10()5
refinery plant, 523
reflectivity, cloud, 390
reformulated fuels, 949*
regional climate change, 371*, 378, 390
regional cloud albedo, 371*
regional particulate model, 637*
regional reference laboratory, 142
regulations, enhanced ozone monitoring
(ROM). 103, 111, 119, 205, 211,306
remote monitoring, 43
remote profilers, 245
remote sensing, 254, 396
remote sensors, 274*
ground-based, 270
residential sources of indoor air
pollution, 824
residential wood combustion, 849*
residues,
carpel, S32
dislodgeable, 832
vinyl floor, 832
risk-based air monitoring, 740
roadway profiles, 283,
rotational spectroscopy, 551
rural sites, 227*, 236, 372, 638*
Russia, air pollution in, 857, 871", 873,
879
sample cartridges, sorbent, 823*
sample preparation methods, 331
samplers,
odor incident, 363
passive, 418, 424*, 437*, 762*
programmable field, 752*
sequential air, 217
sequential cartridge, 93*
sampling,
adsorbent, 598
aircraft, 13
ambient, 149, 164, 173, 195*, 217..
425*, 608, 699, 721*, 740, 910*.
919
automated carbonyl, 198
automated sequential, 198
canister, 83*, 184*, 205, 211,
283, 326, 655*, 656, 664, 685*,
686*. 687, 695", 696*, 752*,
847*, 904*, 912*, 973*, 994, 1005
carbonyl, 84, 198, 211
cloud water, 78*
in sparsely populated areas, 43
multi-canister/multi-cartridge. 205
odor, 953
sequential, 198
surface. 832
VOL'S, 1
whole air, 1, 974, 1005
sampling and analysis information aids,
315
sampling and analysis methods, 315,
348, 354, 361*, 363, 608, 739*,
823*
satellite measurements, 396
saturation monitor, 640
sci ceiling models, 7
scrubbers, ozone, 872*
secondary aerosols, 652*
selective denuder collection system,
425*
semivolatile organic compounds, 29*,
424*, 915*, 916*, 917*, 918*, 919,
925*
sensing, remote, 254, .396
sensitivity studies, 442
sensors,
electrochemical, 416*
ground-based remote, 270
military spectroscopic, 535
remote, 274*
sequential air samplers, 217
sequential cartridge sampler, 93*
sewer systems, 951*
shape factor, 943
"sick room" problem, 781
sideslreuii) smoke, 893
silica cartridges, 195*, 196*, 204*.
1018
siting guidance. 262
small high-pressure cylinders, 489
smog chamber experiments, 918*
' Indicates abstract.
1037
-------
smoke.
cigarette, 887. 893, 898
environmental tobacco, 887, 893, 898
sideslrcam, 893
tobacco, 887, 893, 898
smoking. 778*, 887, 893. 898
SODAR systems. 254, 270
soil,
contaminants, 937
(lux, of NO, 236
moisture, 943
permeability. 937, 943
solid soibents. 982*, 983*
sorbent sample cartridges, 823*
sorbent trapping, 597*
sorbents, solid, 928*, 983*
SOund Detection And Ranging
(SODAR) systems, 254, 270
source test calculations, 362*
sources,
combustion, 348
industrial wastewater, 951*
mobile, 457*, 709, 756
odor. 953
oriented strand board, 361*
residential indoor air pollution, 824
stationary, 315, 331, 339
wastewater sources, 951*
sparsely populated areas, sampling in,
43
spatial characterization, 652*
spatial patterns. 762*, 763
spatial trends, 72,
spatial variation, 65*. 769*, 810
speciation patterns, 296
spectrometry,
filtered noise field ion trap mass.
614*
Fourier transform (ITS), 535
Fourier transform infrared (I'TIR),
583, 588, 714
Fourier transform microwave
(FTMS), 551. 562*
ion trap mass, 699
mass (MS), 30, 315, 348, 517, 597*,
614*, 615, 624, 714, 720*, 722*,
823*, 847*, 903*, 912*, 915*,
1017
photofragmentation/photoionization,
931
spectroscopy, rotational, 551
stability evaluation, 508
standards preparation, 992*
State Implementation IMan (SI11), 441*
static dilution, 992*
stationary sources, 315, 331, 339
statistical data evaluations, 503
Stratospheric Aerosol and Gas
Experiment (SAGE) 11, 396
street canyon, 640
substrates. 2,4-dinitrophenvllivdrazinc
(DNPH). 197*
sulfate, 637*, 652*, 763
acidic, 65", 66
sulfur compounds, 685*. 871*. 1005
sulfur dioxide, 437*, 993*
sulfur-containing pollutants. 576
SUMMA canisters, 655*, 664, 684*,
685*, 686*, 687, 694*, 695*, 696*,
724, 752*, 777*, 904*, 973*, 994
supercritical fluid extraction, 905
suppression techniques, emission, 951*
surface deactivation, in canisters, 904*
surface meteorological instrumentation,
245
surface sampling, 832
surrogates, 893
surveys, citizen-based, 459
SW-846 Method 0010, 331
SW-846 Method 0030, 354
TCE. 326
Teflon fibers, 583
temperature,
combustion, 916*
effects on data collection. 563
temporal allocation profiles, 455*
temporal characterization, 652*
temporal patterns, 762*. 763
temporal profiles, 1017
temporal trends, 72
temporal variation, 236, 755*, 810
terpenes, 686*
test method, extractive emission, 588
* lihl'.tfiius snsirael.
1058
-------
Texas,
Baytown, 993*
Coastal Oxidant Assessment for
Southeast Texas (CX)AST), 173,
631*, 632*, 714
Houston, 164. 173
thermal desorption, 30, 598, 615, 624,
631*, 632*, 823*, 982*
thermionic ionization detector (TID),
339
time-of-flight, 937
Title fII air toxics, 608
TO]4 method, 502. 685*, 687, 694*,
695*, 696*, 720*, 724, 777*, 911*,
992*, 994
tobacco smoke, 887, 893, 898
total gaseous non-methane organic
compounds (TflNMOC), 339
total non-methane organic compounds
(TN.VIOC). 184*, 192", 283
total reactive nitrogen compounds
(NOv), 227*, 235*
trace analysis, direct, 614*
trace gas analysis, 551
tracer decay method, 791
tracers, 791, 893
trajectory,
air, 873
back, 372, 3S4, 873, 879
Hybrid Single-Particle liigrangian
Integrated Trajectories (HY-
SPLIT), 372
transfer efficiency, 832, 991*
transfer systems, gas, 489
transfer velocities, 13
transmissometcr system. 535
transport, influence of, 77*
transport model, aerosol, 21
transuranic mixed waste, 687, 724
trapping,
adsorbent 974
carbonaceous-based triple adsorbent,
30, 55
cold trap dehydration, 912*
controlled desorption, 911*
cryotrapping. 597*, 723*. 911*, 974
ion, 699
sorbenl, 597*
trends,
spatial, 72
temporal, 72
trichlorocthylene (TCE), 326
tubes,
adsorbent, 615
charcoal, 84
multisorbent, 982*
tumors, cancerous, 857
UHP nitrogen, 991*
ultraviolet ozone monitors, 405
uncertainties, emission, 442
Uniontown, Pennsylvania, 66
United States Army, 535
unsaturated oxygenates, 851*
unstructured grid, 21
upper air meteorological data. 270,
274*
upper air meteorological systems, 245
urban airshed models, in North
Carolina, 441*, 442, 454*. 455*,
456*, 457*, 458"
urban sites, 65*, 229, 262, 441*, 442,
454*, 455*, 456*, 457*, 458*, 464,
470, 523, 638*. 639*, 652*, 722*,
756, 762", 763, 769*, 857
validation,
of data, 129
method, 915*
vanadium. 638*
vapor generation methods, 1011
variations,
diurnal, 646, 769*
clevational, 646
spatial, 65*, 769*, 810
temporal, 236, 755*. 810
ventilation systems, in buildings, 817
vinyl floor residues, 832
virtual impactor, 424*
VMT projections, 455*
volatile hydrocarbons, 148*, 283
* Indicates abstract.
1039
-------
volatile organic compounds (VOCs),
30, 43, 128', 129, 135, 142, 205,
282*, 348, 454*, 489, 597*, 615,
624, 631*, 664, 686*, 687, 709,
721*. 722*, 724, 733, 739*. 777*,
781, 804, 823*, 824, 847*, 850*.
898, 903, 973*, 974. 991*. 1024*
emission rate, 1
non-polar, 614*, 615
polar, 517, 551, 562*. 614*, 615.
685*, 771, 903*, 904*, 905, 910*,
911*, 912*. 992*, 994
sampling, 1
volatile organic gases (VOGs). 149
volcanic aerosol, 396
VOST methodology, 354
Wallinglord, Connecticut, 94
warming, greenhouse, 390
waste isolation pilot plant, 687, 724
waste, transuranic mixed. 687, 724
wastewater sources, 951*
wastewater treatment plants, 950*, 953
water management systems, 119, 128*,
624, 911*
whole air sampling and analysis, 1.
974, 1005
wind profilers, 262, 274*
wood combustion, residential, 849*
* Indicates abstract.
1040
-------
AUTHOR INDEX
Adams. Michael F., 361
Adams, Nancy FI., 503
Alkezweeny, A.J., 13
Allen, G„ 76
Allen, G.A., 65, 652, 769
Allen, George, 755, 763
Allen, George A., 646
Allen, Mark K„ 205
Almasi, Elizabeth, 597, 720
Ames, Paul R., 363
Anderson, J.B., 72
Anderson, John, 396
Andresen, U., 562
Aneja, Viney P., 236, 470
Arsenauit, J., 196
Azaroil, Lcnore S., 426
Bacon, D.P., 21
Bai, Rongpo, 228
Bailey, Stephen A., 149
Bajza, Charles, 319
Baker, Mark D„ 361
Baker, Robert D., 92
Ballard, Wendy L., 974
Burnett, Alex, 173
Barrie, L., 1017
Basu, llora, 999
Baumgardencr, Ralph, 72
Bennett, Jon L„ 326
Bell, R.W., 898
Berg tin thai, Jon F„ 953
Berry, MA., 797
Bezuglava, F.mma, 857
Billick. B„ 1017
Binkowski, Francis S., 637
Biria, Parag, 951
Blanchard, F.T., 204
Boehler, William F., 363
Booth, Matthew M., 722
Boothe, Laura, 458
Boris, P., 21
Housqiiet, Ron, 489, 973, 991
Bousquct, Ronald, 135
Bouvicr, F.., 196
Bowser, J.J., 72, 78
Bowyer, James K., 905
Boybeyi, Z., 21
Bradshaw, John, 228
Bradshaw, John D.. 227
Brainaii, Robert S., 425
Brande, Ron, 489, 973
Brande, Ronald, 135
Broadway, G., 187
Broder, Irvine, 762
Brook, J.R., 77
Brown. Joseph, 943
Brubaker, Samuel A., Jr., 937, 943
Brunelli, Peter 149
Bruns, Mark W., 55
Bufalini, Joseph J., 804
Burdick, Nydia, 910
Burkholder. Hazel, 910
Burns, K.L., 378
Burns, K. l.cc, 372
Burris, Rebecca H., 496
Btirsey, Joan T., 331, 348, 354
Burton, R.M., 65, 424, 652, 769
Burton, Robert, 763
Byrd, Lee .Ann B., 993
Callahan, Patrick J., 614. 925
Camaiin, David E., 832, 838
Campo-Pavelka, Jocttc, 363
Cardin, D.B., 185, 502, 694, 695, 752,
912, 992, 1025
Carlcy. Robert J.. 699
Carney, K.R., 29
Carter, Ray R, Jr., 1
Castillejos, Margarita, 755
Chafli'n, Charles T„ 1
Chandler, Victoria, 458
Chang, Ben, 296
Chapman, R.E, 898
Chaung, Jane C., 925
1041
-------
Chaurushia, Ashok, 319
Chen, Jianping, 699
Chen, Pamela U., 496
Childers, Jeffrey W., 529
Clay, Frank R., 362
Clayton, Russ, 810
Coc, Dana L., 918
Coe, David, 186
Cole, E.C., 797
Collins, John F., 282
Conner, Charles P., 993
Conner. Teri L., 282, 283
Connolly. Michael V., 849
Cooncy, Walter, 142
Coppedge, Easter A., 508
Corse, E.W., 204
Costa, D.L., 1011
Crawford, Robert J., 664
Crescenti, Gennaro H., 245
Crist, Howard, 135, 489
Ctoudace, Michael C., 949
Crow, Walt L., 496
Crow, Walter L., 173
Crowley, R., 196
Crume, C.C:., 656, 721
Cure, William W„ 454
Currie, J., 436
Dang, R., 615
Das, Mita, 470
Dattncr, S.L., 847
Davies, D.W., 1011
Davis, Michael F., 1
Dayton, Dave-Paul, 339
Dciningcr, C.K., 384
Deschenes, J.T., 185, 502. 695,
752, 912
Dhannasena. H.P., 29
Dindal, Amy B., 30
Divila, F., 638
Dorosz-Stargardt, Oeraldinc, 103
Dorval, Rick K„ 535
Dougherty, D., 1017
Dowler, Oscar L., 483
Drago, Ron, 148
Drcizlcr, H., 562
Duhrovskaya, R., 967
Duncan, John, 489
Duncan, John W„ 982, 983
Dunlop, Michelle R., 296
Dunn, T., 21
Dyes. Timothy S., 274
Eatough, Delbert J., 781
Edgerton, E.S., 72, 78
Edgerton, F.ric S., 777
Edwards, Pat G.. 496
Egorov. V., 872
Ehrmann, U., 29
Elam, David L., 664
Ellenson, W„ 847
Ellis, J.R., 94
Engel, James R., 535
Erdman, Ted, 111, 142
Evansky, P.A, 1011
Farag. lhab H., 733
Fateley, William G., 1
Fellin, P., 1017
Fernandcs, Carmo, 84
Fernandez, Carmo, 739
Fernandcz-Bremauntz, Adrian, 756
Figueroa, Cristiana M., 326
Fitz-Simons. Terence. 306
Flures, Miguel, 418
Fortmann, Roy, 810
Frank-Supka, Linda, 687, 724
Frederick, George L., 254
Freeman, R.R., 656, 721
Froechtenigt, Joseph F., 7
Fuerst, Robert G., 348, 354
Fujita, Eric M., 173
Fung, Kochy, 195, 723
Galamb, Anne S., 457
Galoustian, E.A., 695, 992, 1025
Gut/, Donald F., 999
Gay, Bruce W„ 804
Gay nor, John, 541
Gaynor, John E, 263
Geiio, Paul W„ 832
Gerald, Nash O., 103, 277
Germain, Andre, 919
Gcyh, AS., 417
Gibbons, John R„ 953
Gibich, John, 164, 173, 496, 631, 632
Ginzburg, Veronica A, 865
Gobcl, M. Jeffrey, 464
1042
-------
Godfrey, Janice, 442
Goff, Douglas R., 173
Gold, Diane, 755
Gorczynski, J.E., Jr., 436
Gordon. Sydney M, 608, 614, 925
Graves, Robert S, 464
Grccnha'gh. Mary E„ 740
Gregorski, D.F., 94
Grift, B.. 1017
Gromov, Sergey A., 865, 879
Grosjean, Daniel, 197, 437, 851, 852
Grosjean, f-ric, 197, 437, 851, 852
Grovcnstcin, J.D., 378, 390
Grovenstcin, John D., 372
Gunn, Kevin N., 791
Guo, Zhishi, 791
Guylon, Jim, 84, 739
Hall, R.M., 797
Rainmaker. Robert M., 1
Hammarstrand, Kent G., 55
Hanst, Philip L, 576
flardesty, R. Michael, 5-11
Harding, H. Jac, 832, 838
Harlin, Karen S., 999
Harlos, David P., 777
Harrcll, Rita M„ 1018
Harris, S., 196
Harshfield, G„ 714
Haltaway, Karen E., 984
Hauze, W.J, 714
Hayes, Carl, 755
Hays, Melinda J., 608
He, D„ 436
Hornby, James B, 306
Henry, Ronald C., 282
Herdman, Ralph D, 2112
Hernandez, Mauricio, 755
Higgins, Cecil E., 30
Highsmith, V. Ro.ss, 810
Hill, Kenneth M, 363
Hill, L. Bruce, 646
Hincs, Avis P., 483
Ho, Y-I,, 21
Hoberecht, H., 615
Holbrook. Benny D, 236
Holdren, Michael, 904
Holdren, Michael W., 83
Holland, John, 489
Ilolman, Sheila C., 455
Hopkins, Brian K., 470
Hopkins, M„ 196
Howie, Reese H., 951
Hoyt, Marilyn P., 915
Hoyt, Steven D., 173
Hudgens. li.r:.. 405
Htiey, Norman A., 7
Hunt, Gary T, 915
Irancta, P, 196
Jackson, Merrill D„ 315, 331, 339, 354
Jakubowski, Edward M, 598
Jenkins, Roger A, 30
Jcsser. Dick, 911
Jcsscr, Richard, 192
Jesser, Richard A., 974
Jeuken, A.B.M.. 77
Johnson, Benjamin T., 92
Johnson, Lairy D., 315, 331, 348. 354
Johnston, Pauline, 1024
Jones, Frank E., 893
Jorgen, Robert T„ 953
Kagann, Robert II, 517
Kamens, Richard M, 916, 917. 918
Kang, Jiangshi, 699
Kanniganti, Rohini, 348
Kantz, Marcus, 142
Karoly, William J„ 361
Katona, Vanessa, 925
Kcever, Jeffrey T., 823, 1024
Kelly, Thomas J., 83. 198, 229, 608
Kemp, Mary G, 111
Kenny, Donald V, 614
Kirshen, Norman, 186, 597, 720
Kita. Dieter, 235
Kleindicnst, T.E., 204. 405
Klepeis. Neil, 887
Klouda, G.A, 847
Klouda, (ieorge A, 849, 850
Knowles, G, 196
Kogan, Vladimir, 950
Koutiakis, P., 65, 417, 424, 652, 769
Koutrakis, Petros, 426, 639, 762, 763,
771
Krasncc, Joseph. 696
Krelschmer. U, 562
1043
-------
Krosl, Kenneth H., 583
Kruschcl, B.D., 898
Kulp, Russell N., 817
Lamp, Torsten, 523
Lander, Neil J., 43
Landis, Dwight A., 93
Lane, Dennis D., 1
Lapurga, Natividad, 184
Larscn, Linda, 111
Lattia, Frank G„ 598
Lawrence, Joy, 639
Lawrimorc, Jay H., 470
I.awson. Douglas R., 173
Lay, I-ori T., 588
Leair, Joseph. 205
Lee, Cheng P., 84
Lee, Cheng Peler, 739
Leese, K.E., 797
Lemirc, G.W.. 931
Lesion, Alan R., 149
Lewis, C.W., 847
Lewis, Charles W., 282, 850
Lewis, Laura, 781
Lewis, Robert G„ 832, 838, 925
Lcwtas, Joclicn, 984
Li, Wen-Whai, 740
Liang, Chris S-K... 763
Lindsey, (Carles G. (Lin), 274
Lindstroni, Andrew B., 903
Linenberg, Amos. 43
Lioy, Paul J., 770
Liu, L-J. Sally, 762
Liu, Shili. 699
Lockhart, L., 1017
Logan, Thomas J., 508
Lunneman, W.A., 119, 204, 847
Lonneman, William A., 173, 283
Lonneman, William G., 470
Lopez, Kimberly, 111
Lopez, Robert II., 724
Lovas, F.J., 551
Lumpkin, Thomas, 640
Lunderville, Dennis R., 733
Lyulko, 1., 967
Ma, Cheng Yu, 30
Madden, Steven C„ 296
Mainga, A.M., 29
Maiscl, Bruce F... 915
Manuszak, Thomas L., 464
Marotz, Glen A., 1
Marshall, Tim L., 1
Maitin, Charles I-., 173
Martin, D., 196
McClenny, William A., 128. 583
McCoicle, M.D., 21
.McCullough, Melissa W., 929
McDonnell, William, 755
McDonough, Susan, 817
McElroy, F.F., 405
McElroy, Frank F., 993
McGaughcy, James K, 331, 354
McGee, J.K., 1011
McMurry, P.H., 76
Mceks, Sarah A., 804
Meincrs, Gregory C., 687
Menetrez, Marc Y., 817
Merrill, Raymond G., 331, 339,
348, 354
Mcssncr, Michael J.. 508
Midgett. M.R., 508
Miller, Edward, 205
Milliron, Jacquclyn J., 296
Mitchell, William, 135, 489
Mitchell, William J., 477, 483
Mixson, Frederic J., 983
Mohan, Krishnan R., 709
Mohnen, V.A., 78
Mohnen, Volker, 72
Moreno, Richard L., 348
Morton, Brian J., 459
Moslcy, Ronald B., 937, 943
Muir. D„ 1017
Mukund, R., 608
Mulik, J., 417
Mulik, James D., 426
Murdoch, Robert W., 508
Murphy, M.J., 94
Murray, George C., 470
Murray, George C., Jr., 464
Murray, Thomas P., 470
Nagda, Niren l_, 1024
Nelson, C.J., 810
Ncvcs, Neuza, 517
Nicholson, Brock M„ 441
Nishioka, Marcia, 910
1044
-------
Noel, Thomas M, 713
Norow/i. Behshad M., 456
Odurn, Juy R., 917
Ogle, Larry, 164, 496, 631, 632
Ogle, Larry D,, 173
Oi, Allen, 111, 142
Ollison. W.M., 4(15
Ollison. Will M, 416
Ondov, J.M., 638
Oil, Wayne. 887
Overton, E.B.. 29
Ozkaynak, Haluk, 778
Pan, Li, 416
Paramonov, Sergey G„ 873
Pardee, Michael A., 211
Parmar, Sucha, 739
Parmar, Suclia S., 84
Parzygnat, Barbara A.B., 277
Patterson, Dwight L., 217
Pau. Jimmy C, 148
Paul, Donald (5., 598
Peckham, S.B., 21
Pennisc, David M., 916
Penrose, William R., 41.6
Philipp, Stephanie B., 339
Phillips, Breda, 640
Pinto, J.P., 853
Pleasant, Mike, 640
Pleil, Joachim, 904, 910
Plcil, Joachim D„ 903, 905
Pollack, Albert J.. 198
Poore, Michael, 184
Poore, Michael \V., 296
Price. J.H., 714
Price, James H., 173
Price, Jim, 496
Purdue, r^arry, 148
Pyle, Bobby," 817
Oi, Chunming, 733
Ouinn, T.L., 638
Radenhcimer, Paul. 164, 496, 631, 632
Rasmusseu, R.A., 173, 847
Rasmusscn, Rei A., 655, 684, 686, 850
Ray, John /)., 418
Reagan. James, 148
Reiss, Richard. 771
Reiss, Sharon, 192, 911
Reiss, Sharon P., 974
Reynolds, Scott, 910
Khodcrick, George 850
Rice, Joann, 129
Riese, Charles E., 254
Ringuclte, Sonia, 919
Robargc, Wayne P., 236
Roberts, Dwight F., 722
Rovinsky, F., 871
Rowe, Newt, 915
Rozacky, Kenneth W., 173
Russwurm, George, 563
Russwurm, George M.. 529
Ryan, P. Barry, 771
Sagebiel, J., 714
Sagebiel, John C., 994
Sams, R.L., 551
Sams, Robert L., 850
Sanborn, Paul A,, 733
Sanchez, David C, 817
Sandholm, Scott, 228
Sandhulm, Scott T., 227
Sarma, R.A., 21
Sausa. R.C.. 931
Saxena, P.. 76
Saxena, V.K., 371, 372, 378.
390, 396
Scarfo, L.J., 94
Scnrfo, Louis 915
Schcffe, Richard D., 295
Schumacher, Philip M. 198
Schuyler, Andrew, 904
Scclcy, I., 187
Sella, Robert L., 283
Serrano, Paulina, 755
Shankar, Uma, 637
Sheetz, L.H., 714
Sheldon, Linda, 823
Sheldon, Linda S., 1024
Shelow, David. 904
Shores, Richard 508
Silvis, Paul, 90-1
Simeonsson, J.B., 931
Sioutas, C. 424
Sioutas, Constanlinos, 426
1045
-------
Siseauaw. Dick, 142
Skcen, J. Todd, 30
Smith, Deborah L., 198
Smith, Richard N., 198
Smyth. Scott, 228
Snoddy, Richard, 937, 943
Somervillc, M., 853
Spaedei, Timothy A., 1023
Sparks, Leslie E., 824
Speizcr, Frank, 755
Spcnccr, M.J.. 898
Spcnglcr, J.D., 77
Spongier, John D., 778
Spictr, Chesler W., 229
Staiiffer, Joe, 904
Stevens, R.K., 847
Stevens, Robert K.. 850, 993
Stilh, J.L., 13
Stone, Charles L., 838
Sirallon, Fied, 470
Sireib, Ellen W.. 477
Stuart, James D„ 699
Suenram, R.D., 551
Suggs, Jack, 135, 489
Suggs, Jack C. 477
SuivH.I1., 65, 652, 769
Suh, Helen, 763
Suh, Helen H., 66
Sweet, Clyde W„ 999
Switzcr, l'aul, 887
Tang, You-Zhi, 1005
Teitz, Avi, 111
Teilz. Avraham, 142
Templeman, Brian D., 270
Terrell. D„ 1011
Thompson, Edgar L., Jr., 529
Thomson,, C, 562
Thomson, M. Stacey, 425
Thurston, George D., 436
Tibbetts, Sarah J., 771
Tichcnor, Bruce A., 791, 824
Tilton, Beverly E., 804
Timin. Brian S., 442
Tipler, A., 187
Tiplcr, Andrew, 615, 624
T(x>m, IX, 1017
Torres, Edward, 950
Tran, Quang, 1005
Tremblay. Jean, 919
Turpin, B.J., 76
Ubcrna, E., 714
Ugarova, Luda, 84
Ulman, J.C., 378
Ulman, James C, 372
Underwood. Margaret A., 496
van Ilaren, Gunther, 523
Vasu, Amy, 930
Vaughan, William M, 563
Villas Boas. Felipe, 517
Wagoner, Denny E., 331
Waldman, Jed M., 763
Walsh, L.C., 1011
Waller, T„ 196
Wang, H., 685
Ward, Gerald F„ 229
Wardrup, Kris, 781
Washburn, Stephen T., 740
Watts, Randall R., 984
Weber, Konradin. 523
Weicherl, Bradley A, 92
Weidcmann, Johannes, 523
WciscL Clifford I'.. 709
Whitaker, Donald A., 1024
Williams, Edwin L. Ill, 852
Williams, Ron W., 984
Williamson, Ashley, 817
Wilson, Nancy K, 887, 925
Wilson, W.E., 652, 769
Wilson. William E, 763, 770
Wincgar, E.D., 656
Wincgar, Erie D.. 721
Wirislow, Michael G., 92, 722
Wisbith, Anthony S., 687
Wolfe, Daniel, 541
Wolfson, J.M., 417
Wolfson, J. Mikhail, 426
Wu, Qiuaii-Fu, 687, 724
Xue, Jianping, 778
Yoong. Matthias J., 211
Young, S., 21
1046
-------
Zack, J., 21
Zdenka, Michael P., 66
Zhang, Junfcng, 770
Zhao, Yanzeng, 541
Zieglcr, Gary S., 254
Zielinska, B., 714
Zielinsku, Barbara, 994
Zimmcr, Robert A., 687, 724
Zukon Charles J., 951
Zwicker, Judith O., 563
1047
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