EPA-600/3-77-080
        1977                                                     Ecological Research Series

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                                                          Office of Research and Development
                                                   , -  •  O.S. EwNFdMRSWtil f*reteeffro Ageney
                                                Researclr Triangle Park, North Carolina  27711

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                RESEARCH REPORTING SERIES

Research reports of the Office of Research and Development, U S. Environmental
Protection Agency, have been grouped into nine series  These nine broad cate-
gories were established to facilitate further development and  application of en-
vironmental technology  Elimination of traditional grouping  was  consciously
planned to foster technology transfer and a maximum interface in related fields
The nine series are-

      1   Environmental  Health Effects Research
      2   Environmental  Protection Technology
      3   Ecological Research
      4   Environmental  Monitoring
      5   Socioeconomic Environmental Studies
      6   Scientific and Technical Assessment Reports (STAR)
      7   Interagency Energy-Environment Research and  Development
      8   "Special" Reports
      9   Miscellaneous Reports

This report has been assigned to the ECOLOGICAL RESEARCH series. This series
describes research on the effects of pollution on humans, plant and animal spe-
cies, and materials Problems  are assessed for their long- and short-term influ-
ences Investigations include formation, transport, and pathway studies to deter-
mine the fate of pollutants and their effects  This work provides the technical basis
for setting standards to minimize undesirable changes in living organisms in the
aquatic, terrestrial, and atmospheric environments
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.

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                                             EPA-600/3-77-080
                                             August  1977
           AEROSOL RESEARCH BRANCH
          ANNUAL REPORT FY 1976/76A
                  Edited by
   William E. Wilson and Christine Danskin
 Atmospheric Chemistry and Physics Division
 Environmental Sciences Research Laboratory
Research Triangle Park, North Carolina  27711
 ENVIRONMENTAL SCIENCES RESEARCH LABORATORY
     OFFICE OF RESEARCH AND DEVELOPMENT
    U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, NORTH CAROLINA  27711
             T ~ '         -. •• f

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                                 DISCLAIMER

     This report has been reviewed by the Environmental Sciences Research
Laboratory, U.S. Environmental Protection Agency, and approved for
publication.  Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
                                     ii

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                                  ABSTRACT

     The research program of the Aerosol Research Branch includes research
grants and contracts at institutions in many parts of the United States, in
addition to an intramural program.  The purpose of these projects is to
study the chemical and physical properties of aerosols, identify the mecha-
nisms of aerosol formation and removal, and conduct experiments to measure
these rates.
     The results of the research are being used (1) to establish the contri-
bution of the various sources to the ambient atmospheric aerosol loading,
(2) to characterize urban, natural, and primary and secondary aerosols,  (3)
to develop quantitative descriptions of the generation and removal rates
associated with each major aerosol source and sink, (4) to quantify the
effects of aerosol on atmospheric chemical reactions, and (5) as a scientific
basis for recommending regulatory actions concerned with air quality
improvements.
     In addition to base funding through EPA's Office of Research and Develop-
ment, the Aerosol Research Branch (ARB) also receives funds from the Federal
Interagency Energy/Environment Research and Development Program.  This pro-
gram is coordinated by the Office of Energy, Minerals, and Industry, Dr.
Steven Gage, Deputy Assistant Administrator.  The tasks conducted by ARB
under this program relate to the transport and fate of pollutants associated
with energy sources.
     Tasks funded by the Energy/Environment program are not described in this
report but are listed by title and principal investigator.  The FY 1976/76A
annual report of the energy program is found in EPA Report 600/7-77-076,,
                                    iii

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                               CONTENTS
Abstract	,  »	

Abbreviated Functional Statements   	    ix

Acknowledgements 	     x

     1.   Introduction 	     1

     2.   Summary of Aerosol Research Branch Fiscal Year
          1976 Program by Project	     2

     3.   Project Reports

          A.   ATMOSPHERIC PROCESSES AND EFFECTS

               1.   Aerosol Formation, Growth, and Removal

               Formation of Atmospheric Aerosols—Parametric
                 Measurement of Submicron Atmospheric Aerosols,
                 by K.T. Whitby	     4

               To Investigate the Atmospheric Contribution of
                 Biogenic Sulfur  to the Urban Load of Sulfur
                 Aerosols, by D.R.  Hitchcock 	     8

               Experimental Study of Aerosol Formation
                 Mechanisms in a  Controlled Atmosphere, by
                 D.L. Fox	    11

               Formation of Atmospheric Aerosols—Smog
                 Chamber Research,  by K.T. Whitby	    13

               Smog Chamber Study of Sulfur Dioxide Oxidation
                 and Aerosol Formation Mechanisms, by W.C. Kochmond.    14

               Study of Vapor Pressure of Systems Forming
                 Atmospheric Aerosols, by G. Brown 	    16

               Formation of Atmospheric Aerosols—Size
                 Distribution Models for Atmospheric Aerosols,
                 by K.T. Whitby	    17

               Aerosol Dynamics, by J.R. Brock 	    24

               Biogenic Emission  of Aerosol Precursors, by
                 L.L. Spiller	    28

               Metal Sulfite Complexes, by D. Lawing	    29

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2.   Aerosol Characterization and Sources

Sources and Trace Metals in Urban Aerosols.
  Sub-Task Title:  Urban, Non-urban, and Marine
  Aerosol Studies, by J.W. Winchester 	    31

Relationship of the Smog Aerosol to Pollution
  Sources, by S.K. Friedlander	    36

A Study of the Identify and Sources of
  Atmospheric Aerosols, by R.G. Draftz  	    38

Analysis of Air Pollutants by Mass Spectroscopy,
  by A.L. Crittenden	    40

Chemical Characterization of Model Aerosols,
  by D. Mendenhall	    42

Sources and Trace Metals in Urban Aerosols.
  Sub-Task Title:  Aerosols Properties Relevant to
  Health Effects, by J.W. Winchester  	    46

Aerosol Sources Program, by R.K. Patterson   	    50

Aerosol Microscopy, by J. Gerhard 	    51

Field Expedition to Phoenix, AZ, by J.L. Durham ...    52

Analytical Support for Aerosol Studies, by
  R.K. Patterson	    53

3.   Visibility and Radiation Effects

Optical Effects of Atmospheric Aerosol, by
  A.P. Waggoner	    55

4.   Heterogeneous Reactions

The Role of Gas-Solid Interactions in Air
  Pollution, by H.S. Judeikis	    58

Structure and Reactivity of Adsorbed Oxides  of
  Sulfur and Other Small Sulfur-Containing
  Molecules, by J.H. Lunsford	    62

Structure and Reactivity of Adsorbed Oxides
  of Sulfur, by J.H. Lunsford	    65

Reactions of Sulfur Dioxide in Aerosols, by
  D.M. Himmelblau	    69

Mass Transport Models, by J.H. Overton	    70
                      vz

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     5.    Technique Development

     Formation of Atmospheric Aerosols—Nonideal
       Characteristics of Impactors, by K.T. Whitby  ...    76

     Sources and Trace Metals in Urban Aerosols.
       Sub-Task Title:  Development and Application
       of Analytical Sampling Techniques, by J.W. Winchester  78

     Formation of Atmospheric Aerosols—Development
       of a Sulfur Aerosol Analyzer, by K.T. Whitby  ...    82

     Simultaneous Comparison of the EAA and the
       Diffusion Battery for Atmospheric Aerosol, by
       J. Bricard	    83

     Determination of Sulfate Ion Concentrations in
       Human and Animal Serum using High Pressure Liquid
       Chromatography, by L.L. Spiller 	    84

     Comparison Study of Data Collected with the
       Dichotomous and High-Volume Samplers, by
       T. McCarthy	    85

     A Cyrogenic Procedure for Concentrating Rating
       Trace Gases in the Atmosphere, by L.L. Spiller. .  .    86

     Collection of Atmospheric N0~ by Treated
       Filters, by L.L. Spiller	    87

     Instrumentation for Monitoring Meteorological
       Data, by L.L. Spiller	    88

     Improvement of "Streaker" Technique for Automated
       Appendices Collection and Analysis of Aerosols,
       by W. Nelson	    89

B.   AUTO EXHAUST CATALYST PROGRAM

     Roadway Aerosol Studies during General Motors
       Sulfate Dispersion Study, by E.S. Macias  	    91

     Formation of Atmospheric Aerosols—Aerosol Size
       Distributions and Concentrations Measured During
       the General Motors Sulfate Study, by K.T. Whitby   .    94

     Sources and Trace Metals in Urban Aerosols.
       Sub-Task Title:  Freeway Aerosol Studies, by
       J.W. Winchester   	   100

     Dynamics of Automotive Sulfate, by J.R. Brock ....   104
                           VII

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               The General Motor-Environmental Protection Agency
                 Sulfate Dispersion Experiment in October 1975
                 at the General Motor, Milford Test Track, by
                 L.L. Spiller	   106

               Atmospheric Behavior of Catalyst-Generated
                 Aerosols from Source to Receptor, by J.L. Durham   .   107
Appendices
     A.   List of ARE Projects funded by the Federal Interagency
          Energy/Environment Research and Development Program
          (Titles and Principal Investigator)	   Ill

     B.   Publications, Presentation, and Theses Listing 	   113

     C.   Publications, Presentations, and Theses Listing Index  .  .   127
                                    Vlll

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                 .. ABBREVIATED FUNCTIONAL  STATEMENTS

     The Environmental Sciences Research Laboratory (ESRL) conducts research
programs in the physical sciences to detect, define, and quantify the effects
of air pollution on urban, regional, and global atmospheres, and the sub-
sequent impact on air and water quality and land use.  ESRL is responsible
for the planning, implementation, and management of research and development
programs designed to quantitate the relationships between emissions of
pollutants from all types of sources, air quality, and atmospheric effects.
ESRL also plans, implements, and manages a research and development program
to provide needed techniques and instrumentation for the measurement and
characterization of pollutants in the ambient air and in the emissions from
all types of sources.  ESRL's research and development program consists of
grants, contracts,  and in-house work.

     The Atmospheric Chemistry and Physics Division (ACPD) conducts research
programs (1) to characterize the chemical and physical properties of ambient
air pollutants and (2) to relate quantitatively the chemical and physical
properties of emissions from mobile, stationary, and natural sources to the
effects on air and water quality and land use.  ACPD also develops techniques
and instrumentation for the measurement and characterization of gaseous and
aerosol pollutants.

     The Aerosol Research Branch (ARB) studies the chemical and physical
properties of aerosols, identifies the mechanisms of aerosol formation and
removal, and conducts experiments to measure these rates.  The properties
of atmospheric aerosols are related to health and welfare effects for the
purpose of selective control of pollutant sources.
                                    ix

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                           ACKNOWLEDGEMENTS
     The program of the Aerosol Research Branch is under the scientific
direction of A.P. Altshuller, Director,  Environmental Sciences Research
Laboratory.  EPA funds are provided through OALWU, Thomas Murphy, DAA
(Transport and Transformation Program) and OHEE, Delbert Earth, DAA
(Catalyst Program).  Federal Interagency Energy/Environment Research and
Development Program funds (Project MISTT) are provided through OEMI, Steven
Gage, DAA.  We also thank Robert Papetti and Deran Pashayan, OALWU, and
Greg D'Alessio, OEMI, for management support.
                                    x

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                         1.  INTRODUCTION

     The Aerosol Research Branch (ARE),  as part of the Environmental
Sciences Research Laboratory of the U.S. Environmental Protection Agency,
administers an extramural research program consisting of grants and contracts
at institutions in many parts of the United States.  In addition to the
extramural program, ARE conducts a modest in-house program.  Since the major
responsibility of ARB is to conduct an extramural research program, the
in-house program is designed to support the extramural program.  It has three
major functions:  1) to provide rapid-response capability to respond to
agency needs, 2) to test out concepts prior to establishing extramural pro-
grams, and 3) to maintain the scientific competence of the EPA project
officers.  It is considered extremely important that the scientific competence
and reputation of ARB's project officers be such that grant and contract
principal investigators consider them as scientific peers rather than funding
clerks.
     This progress report presents results of tasks active during fiscal
years 1976 and 1976A.  The reports have been classified into projects as
shown in the Summary of Aerosol Research Branch Fiscal 1976 Program by
Project.  ARB tasks funded through the Federal Interagency Energy/Environment
Research and Development Program are listed by Title and Principal Investi-
gators in the Appendix.  The Appendix also includes a Publications, Presenta-
tions, and Thesis Listing.   The Publications List includes only EPA funded
research authored by the investigators funded through the Aerosol Research
Branch.  Following the listing is an Authors Index.  To find a particular
author's work in the Publications List first find the author's name in the
Index and then turn to the Publications List.

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              2.  SUMMARY OF AEROSOL RESEARCH BRANCH
                  FISCAL YEAR 1976 PROGRAM BY PROJECT
Project MISTT  (Midwest Interstate Sulfur Transformation and Transport)

     A study of pollutant transformations and removal during atmospheric
transport over various scale lengths.
          Urban scale (50 km):  Tracer and portable chamber studies.
          Power plant plumes (250 km):  Aircraft measurements.
          Urban plumes (500 km):  Aircraft and ground measurements.
          Blobs (2000 km):   Weather Service visibility reports and a ground
               network of 14 stations extending from eastern Kansas to
               New England.
          Model Development and Data Analysis.

     Funded by the Federal Interagency Energy/Environment Research and
Development Program through USEPA, ORD, OEMI.  Program Element 1NE625.

Auto-Exhaust Catalyst Program

     Determination of chemical and physical properties of sulfuric acid
aerosol produced by automobile catalysts.

     Funded by USEPA, ORD,  OHEE.  Program Element 1AA601.

Atmospheric Processes and Effects

     Aerosol Formation, Growth and Removal.  Identification of physical and
chemical mechanisms for aerosols processes in the atmosphere, measurement
of important rate constants, and development of models for formation, growth
and removal of atmospheric aerosols.

     Aerosol Characterization and Sources.  The utilization of physical
properties, elemental and chemical analyses, and microscopy for the charac-
terization of atmospheric aerosols and the use of this information to
determine the primary and secondary source contributions to urban pollution.

     Visibility and Radiation Effects.  Measurement of pertinent aerosol
properties and determination of relationships between concentration, com-
position, size and effects.

     Heterogeneous Reactions.  Measurement of the rates and mechanisms of
reactions involving gases with surfaces or condensed phases.

     Technique Development.  Development of new instruments or techniques
required for the aerosol research program.

     Funded by USEPA, ORD, OALWU.  Program Element 1AA603 and 1AD712.

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               A.   ATMOSPHERIC PROCESSES AND EFFECTS
     1.   Aerosol Formation, Growth, and Removal.  Identification of
physical and chemical mechanisms for aerosols processes in the atmosphere,
measurement of important rate constants, and development of models for
formation, growth and removal of atmospheric aerosols.
   Funded by USEPA, ORD, OALWU.  Program Element 1AA603 and 1AD712.

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1.   Task Title:   Formation of Atmospheric Aerosols  -  Parametric Measurement
     of Submicron Atmospheric Aerosols

2.   Objective:

          To develop and validate a method for calculating the submicron
     size distribution of atmospheric aerosols from  three integral  measure-
     ments on the aerosol, namely, concentration nuclei  count, electric
     charger current, and the response of an integrating nephelometer.

3.   Institution:  University of Minnesota, Minneapolis, Minnesota
     Investigator:  K.T. Whitby

4.   EPA Project Officer:  W.E. Wilson

5.   Progress:

          Studies by G.M. Sverdrup were conducted in order to determine how
     many aerosol parameters must be measured to adequately specify the
     number, surface, and volume weightings of a submicron atmospheric  aerosol
     size distribution.   A constraint placed upon the  instrumentation was
     that all instruments must operate in a continuous mode.   This  eliminated
     the need for bag samples in order to accommodate  instruments'  long
     sampling periods.

          A minimum of three instruments (e.g., condensation nuclei counter,
     aerosol charger, and nephelometer)'are necessary  to obtain significant
     information about the entire submicron size spectrum.  Figure  1 shows
     the sensitivities of the three instruments as a function of particle
     size for a family of size distributions.  The areas under the  three
     curves are equal to the total number concentration  (N), the total  current
     from the charged aerosol (I) and the aerosol light  scattering  coefficient
     (bsp).  The nuclei  counter and aerosol charger  sensitivities were
     experimentally determined.  The nephelometer sensitivity was calculated
     from Mie theory.

          The submicron  size distribution was determined by calculating the
     expected values of N, I, and bsp, using a bimodal log-normal size  distri-
     bution model.  Three of the log-normal function parameters were held
     fixed while the other three were varied. The difference  between the
     theoretical  and  measured  values of N,  I, and bsp were minimized until
     these  differences  were  within  the  instrument uncertainty for  all  three
     instruments.

           Figure  2  shows  plots  of a comparison between  the size  distributions
     obtained  from  the  minimization procedure and the measured  size.   The
     difference  in  total  number concentration is  zero due to  the minimization.
     The  difference in  total surface  concentration  is 0.4%,  in  total volume
     13%.   These  differences are  due  to  instrument  uncertainty.

6.   Publications,  Presentations,  Theses:

     1.    Sverdrup, G.M.   Parametric  Measurement of Submicron Atmospheric
     Aerosols.   Ph.D. Thesis.   Submitted  to:  Mechanical  Engineering Depart-
     ment,  University of Minnesota.   November  1976.

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7.    Plans:
     1.    The procedures developed In this task will  be applied to data
     acquired during the 1976 summer MISTT projects.   The results will be
     compared with actual size distributions measured with the Minnesota
     Aerosol  Analyzing System.

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1.    Task Title:   Investigate the Atmospheric Contribution  of Biogenic
                  Sulfur to the Urban Load of Sulfur Aerosols
2.    Objective:

          To investigate the atmospheric contribution of biogenic  sulfur
     to the urban load of sulfur aerosols.

3.    Institution:  Hitchcock Associates
     Investigator:   Diane Hitchcock

4.    EPA Project Officer:  L.L. Spiller

5.    Progress:

          The existence of "natural"  biogenic sulfur contributions to the
     atmosphere  has been recognized  for  some time,  but estimates  of the
     strength of these natural  sources or their distribution is  virtually
     unknown.  Little useful information exists for assessing the  claim
     that biogenic S sources can contribute significantly to the  load of
     gaseous or  particulate S in urban sites, or to the non-urban  load
     ("background"  level).

          Many biological processes  produce volatile sulfur compounds, and
     may be responsible for biogenic  S emission.  The most  important of
     these processes appears to be the metabolism of the bacterial sulfate
     reducers—chiefly of the species Desulfovibrio desulfuricans.  These
     organisms are obligate anaerobes and inhabit aquatic environments
     where oxygen is absent.  They use dissolved sulfate as a source of
     oxygen in the oxidation of available organic matter, producing H?S
     as a metabolic by-product.

          H?S production by bacterial sulfate reducers may  proceed at an
     extremely rapid rate under suitable conditions.  Field studies and
     laboratory  experiments show that rates of 50 to 100 metric  tons per
     km^ per yr  may be common in suitable habitats.  But no quantitative
     data exist, and very few measurements have been made of atmospheric
     sulfides near sites where sulfate reduction is active.

          Included are preliminary results of a field study designed to
     survey the  distribution of atmospheric biogenic sulfur compounds near
     sites where they are produced.

          Atmospheric reactive sulfides  and sulfur  dioxide  were  measured in
     a tidal marsh near Morehead City, North Carolina.  AgNOo and LiOH
     impregnated mi Hi pore filters were  used for collecting the  samples,
     and analyzing for elemental S by means of X-ray fluorescence spectro-
     scopy.  Sample collection intervals of 12, 6,  and 4 hours were synchro-
     nized with  tidal movements in order to observe the relationship between
     exposure of the heavily organic H^S-rich muds  at low tide,  and the level
     of sulfide in the atmosphere.  Similarly synchronized 12 and 6-hour
     samples were collected at a control site, a two-story building roof top
     on the shore of Bogue Sound, approximately 1.5 miles from the marsh site.

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         Sulfide levels in the marsh averaged 4.6 ppb over the  13-day field
    study.  A strong dependence on the tidal  cycle was revealed by the 4-hour
    samples taken at successive high and low  tides.  Sulfide  was rarely
    detected during high tide, and did not exceed 2 ppb.   Low-tide levels
    ranged from 2 to 57 ppb and averaged 10 ppb.   The highest levels  were
    observed at night when local  wind movements were minimal.  At night,
    the 10-tide sulfide levels averaged 5.5 m sec-1.   Attempts  to detect
    sulfides in the air at the control site were  generally unsuccessful.
    Of 26 12-hour samples, only 4 showed detectable levels of sulfides, and
    these did not exceed 1.5 ppb. (Fig. 1)

         A second set of measurements was made in November to determine
    whether biogenic S is present in the atmosphere at sites  where no f^S-rich
    muds are exposed during the tidal cycle,  but  where reducing sediments
    occur under water.  Measurements were made for 24 and  6-hour intervals
    at 3 sites, 25 to 30 miles from any sources of anthropogenic SOp.  One
    of these sites is at the Coast Guard Station  at Bogue  Inlet on Bogue Banks,
    and the others are a few miles north on White Oak River.   Sulfide-rich
    muds occur at both the latter sites, but  are  never exposed  by the tide.
    No sulfide-rich muds occur near the Coast Guard site,  but some exist
    inside the sound.  (Water from the sound  passes through the inlet four
    times daily, and it may contain h^S derived from bottom sediments).
    The results showed higher levels of atmospheric sulfur than originally
    anticipated, with sulfide levels ranging  from 0.5 to  nearly 5 ppb; S0£
    ranged from below detection limits to over 20 ppb. The means were
    1.5 to 1.9 ppb sulfide:  4.5 to 4.8 ppb SOp.   Wind speeds were usually
    very high, and temperatures abnormally cold for this  time of year. The
    atmospheric S is biogenic, and we infer that  it is derived  from the
    marine muds near the monitoring sites, although fresh-water swamps in
    surrounding woods cannot be ruled out.

6.  Publications, Presentation, and Theses:  None.

7.  Plans:

    1.  This survey will be repeated and extended with the following changes
    in measurement procedures:
    a)  sulfide measurements with durations from one to two hours; b) measure-
    ments of S0£ by means of a Meloy #FA-285  at best possible sensitivity
    (1 ppb), with short integration time (2 sec.); c) measurement of ozone
    and possibly other potential  oxidizers.

    2.  Studies will be conducted at the same sites as in  1976  and at a new
    site.  The new site will be a brackish water  site further inland, with
    little tidal flushing and less sea water  sulfate.

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 16

 14

 12

 10
         DAY
NIGHT
                                  V/i
                  LOW TIDE
                  HIGH TIDE
Figure 1.   (Note  - These numbers are  5  ppp.,  0,15 ppb and 1.4  ppb)
                             10

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!•    Task Title:   Experimental  Study of Aerosol  Formation Mechanisms in
     a Controlled Atmosphere.

2.    Objective:

          To conduct experiments in a large outdoor chamber to obtain data
     for modeling purposes on  aerosol formation  mechanisms from chemical
     systems containing sulfur.

3.    Institution:  University  of North Carolina  at Chapel Hill, Chapel
     Hill, North Carolina
     Investigator:  D.L. Fox

4.    EPA Project Officer:  J.L. Durham

5.    Progress:

          An investigation of  photochemical systems containing hydrocarbons,
     oxides of nitrogen, and sulfur dioxide has  been conducted with the use
     of a long-path infrared (LPIR) -fourier transform spectrometer (FTS).
     This instrument has been  successfully operated in situ in the outdoor
     chamber and has provided  the analytical capability to measure gas
     phase product concentrations of some species not ordinarily measured
     in smog chamber experiments (e.g., formic acid and peroxyacyl nitrate).
     In propylene, NO^and S02 systems, SOp oxidation increases during the
     N0-N02 crossover region;  the same region where modeling predicts an
     increased flux of free radicals to be present.  Computer modeling of
     these systems has been improved by knowledge of the product concentra-
     tions measured through the course of an experiment by the LPIR-FTS
     system.

          In the presence of sunlight, sulfur dioxide in ambient air will
     be oxidized to form sulfuric acid aerosol.   One mechanism in this
     conversion process is thought to be hydroxyl radical (OH) attack on
     S02, which results in the formation of H2S04 vapor.  Then the acid
     vapor either condenses on existing particles or nucleation of new
     particles occurs in the presence of water vapor.  Results from the
     outdoor chamber show the  occurrence of both of these gas-to-particle
     conversion mechanisms under certain conditions.  When S02 in background
     air is subjected to sunlight of variable intensity, fluctuations in the
     condensation nuclei count correspond to variations in sunlight intensity
     caused by clouds temporarily blocking the sun.  Measurements of particle
     size distribution as a function of time, show the formation of fine
     particles as the intensity of sunlight increases rapidly.  These observa-
     tions are consistent with the hypothesized  OH attack on S02-  Hydroxyl
     radical concentrations will vary with changes in light intensity.  When
     S02 concentrations are changing very slowly with time, the conversion
     rate is primarily dependent on fluctuations in OH concentration.

          The activity of H2S04 in the gas phase controls the pathway for  gas-
     to-particle conversion.  At a certain level of activity H2S04 will
     nucleate even in the presence of existing particle surface area.  This
     phenomena has been observed with rapid changes in sunlight.
                                     11

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          Aerosol  samples have been  collected on  glass  fiber and membrane
     filters, and  elemental  analysis of the collected particles  have been
     performed using X-ray fluorescence.   The X-ray fluorescence data and
     the data from an electrical  aerosol  analyzer allow estimation of the
     composition of the evolving  aerosol  as a function  of time,  relative
     humidity and  other parameters  of interest.   Comparison of the mass
     of sulfur appearing in the aerosol  particles with  that lost from the
     gas phase also is an aid in  the determination of the sulfur budget for
     the environmental system.  Since X-ray fluorescence is non-destructive,
     further analysis of the same samples is possible,  thus providing a
     reference against which results of other methods can be compared.

6.   Publications. Presentation and  Theses:

     1.   Fox, D.L., J.E. Sickles,  M.R.  Kuhlman,  P.C. Reist and W.E. Wilson.
     1975.  Design and Operating  Parameters for  a Large Ambient Aerosol
     Chamber.  J.  Air Poll.  Cont. Assoc.   25:1049-1053.

     2.   Fox, D.L., M.R. Kuhlman and P.C. Reist.  1976.  Sulfate Aerosol
     Formation Under Conditions of Variable Light Density.   Proceedings
     of International Conference  on  Colloids and Interfaces.  Academic Press.
     In Press.

     3.   Reist, P.C., W. Marlow and G.  Dwiggins.  1976.  Aspects of the
     Performance of the Electrical  Aerosol Analyzer Under Nonideal Conditions.
     0. Aerosol Sci.  In Press.

     4.   Wright,  R.S.  1976.  M.S.  Thesis.  Feasibility Study for the
     Use of a Long-Path Infrared Spectrometer in an Outdoor Chamber.

     5.   Dwiggins, G.A.  1976.  M.S. Thesis. The Effect of Trace Gaseous
     Constituents  in the Air on Data from the Electrical Aerosol Size Analyzer.

7.   Plans:

     1.   To continue studies in outdoor chamber on sulfate aerosol formation.

     2.   An exploring wire generator will be used for studies of the effect
     of pre-existing nuclei on aerosol growth.
                                   12

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1.  Task Title:  Formation of Atmospheric Aerosols - Smog Chamber Research.

2.  Objective:

         To study the formation and growth of aerosols formed from the photo-
    oxidation of mixtures of SCL,  hydrocarbons, and NO .
                               £                      X

3.  Institution:  University of Minnesota, Minneapolis, Minnesota
    Investigator:  K.T. Whitby

4.  EPA Project Officer:  W.E. Wilson

5.  Progress

         Studies by Kittelson and his students have been  made of mixtures
    of NC + NO + S02 in the University of Minnesota's 18  m3 smog chamber.

         Analysis of hydrocarbon + NO + S02 experiments has shown a very
    close coupling between aerosol and chemical behavior.  Disappearance
    of NO and onset of 03 formation are accompanied by a  sudden increase in
    the rate of aerosol formation  and a broadening of the aerosol size dis-
    tribution.
                                                                      3
         Measurements have been made by Kwok of wall losses in the 18m  smog
    chamber.  Under typical sampling conditions the bag surface-to-volurae-,
    ratio is 2.2 m- , and the first order wall loss constant is 0,19 hr." .

         The chamber lights were upgraded to double the current light intensity

    Of kdNO£ = °'2 min" '


6.  Publications, Presentations, Theses:

    1.  Kwok, Kui-Chiu.  1975.  Coagulation and Wall Losses in a Smog Chamber.
    M.S. Thesis.  Mechanical Engineering Department, University of Minnesota, MN.

    i.  Kocmond, W.C., D.B. Kittelson, J.L. Yang and K.L, Demerjian.  1975.   Study
    of Aerosol Formation in Photochemical Air Pollution.   EPA-650/13-75-007.

    3.  Kocmond, W.C., D.B. Kittelson, J.L. Yang, K.L. Demerjian and K.T, Whitby.
    1975.   Aerosol  Formation in Simple Photochemical Systems.   Environ.  Sci. and
    Tech.

    4.  Kocmond, W.C., D.B. Kittelson, J.L. Yang and K.L. Demerjian.  Determination
    of Formation Mechanisms and Composition of Photochemical  Aerosols.  Calspan
    Corp.,  Buffalo, NY.  August 31, 1973.
    5.   Clark, W.E.  and K.T.  Whitby.   1975,   Measurement of Aerosols by the
    Photochemical  Oxidation of S02 in Air.

7.  Plans:  1.  To write papers and reports.
Photochemical  Oxidation of S02 in Air.   J.  Colloid Interface  Sci.   51:477-490.
                                       13

-------
1.  Task Title:  Smog Chamber Study of Sulfur Dioxide Oxidation and Aerosol
    Formation Mechanisms.

2.  Objective:

         To assess the SOg oxidation rates and mechanisms under varying ambient
    environments.

         To investigate chemical  and aerosol  behavior under homogeneous photo-
    oxidation conditions.

         To study surface  and droplet catalytic effects on S02 oxidation as
    might be expected under in-cloud transformation and power plant plume
    conditons.

3.  Institution:  Calspan
    Investigator:  W.C. Kocmond
                   J.Y. Yang

4.  EPA Project Officer:  B. Dimetriades

5.  Progress:

         The Calspan smog  chamber facility consists of a cylindrical  chamber,
    30 feet (9.14 meters)  in diameter and 30  feet (9.14 meters) high, enclosing
    a volume of 20,800 ft^ (590m3).  The inner chamber surface is coated with a
    fluoroepoxy-type urethane, which has surface energy and reactivity properties
    comparable to those of FEP Teflon.  Illumination within the chamber is provided
    by 28.6kw of fluorescent blacklight and sunlamps installed inside 24 lighting
    modules and arranged in eight vertical channels attached to the wall of the
    chamber.  Measured light intensity, using the k^ [N02] method reported by
    Stedman and Niki (1973), is k^ ^ 0.35 min~^.  Varying light intensities  can
    be provided by selectively turning off some of the light modules and lamps.
    Air purification within the chamber is accomplished by recirculating the
    air through a series of absolute and activated carbon filters.

         To date over 60 experiments have been conducted using systems ranging
    from S02 in clean air, to irradiations of auto exhaust + NOX + S02-  A
    number of preliminary  experiments have also been performed using the laboratory
    cloud + SOg system.  Numerous tests were  conducted to examine aerosol collection
    methods and sulfate analysis techniques.   From an analysis of the smog chamber
    aerosol and chemistry  data, the following points can be made:

         1.  The S02 photooxidation rate in hydrocarbon + NOX polluted air
    is accelerated over that for the S02 + clean air systems, and generally lies
    in the range of 1 to 3% hr-1.  Results of sulfate analysis show that the S02
    photooxidation rate during the accelerated growth period is about 2.3% hr-1
    for the propylene + NOX + S02 system, and approximately 1.5% hr-1 for the
    cyclohexene + NOX + S02 system.

         2.  Total aerosol production is greatly accelerated in the propylene
    or cyclohexene + NOX + S02 reaction systems over that observed for the HC
    + NOX system alone.  The measured maximum rate of aerosol formation was 20
    times greater for the propylene + NOX + S02 test mix compared to the propylene
    + NOX system without S02-  Comparison of the aerosol volume production data
    in these two systems suggests that organic aerosol formation may be

                                       14

-------
     enhanced due to the presence of S02-

          3.   For the auto exhaust + 862 experiments, the average photooxidation rate
     of S02 as determined from chemical analysis was about the same for all experiments,
     with or without combustion nuclei.  In these experiments, however, a HC/NOX ratio
     of about 6:1 was used and NO disappearance did not occur in less than about six
     hours.  During this lengthy period, any effects of the combustion nuclei on
     subsequent aerosol formation presumable would have been obscured.  Additional
     tests of shorter duration are recommended to permit the determination of RSQ^
     after NO oxidation is completed and appreciable ozone has been formed.  Ratios
     of HC/NOX of about 15:1 will be needed to significantly accelerate the NO
     oxidation process.

          4.   Initial particle concentrations were an order of magnitude higher for
     the auto exhaust tests using leaded fuel in comparison to tests with non-leaded
     fuel.  Once irradiation was started, the maximum particle concentration and rate
     of aerosol production were also higher for the leaded fuel cases.

          5.   The chemical (barium perchlorate titrations) and aerosol (EAA data)
     methods for determining R$QO were only comparable during the initial stages of
     the auto exhaust experiments.  Later, the EAA analysis was higher, suggesting
     that the aerosols thus formed were of a mixed nature (i.e. organics, nitrates
     and sulfates).

          6.   The largest amount of light-scattering aerosol was formed in the
     leaded fuel auto exhaust experiments.

          7.   Procedures have been established for producing realistic clouds within
     the Calspan smog chamber for studies of in-cloud $02 to sulfate transformation.

          8.   Efforts directed toward obtaining reliable aerosol samples and
     establishing usable analysis procedured for determining sulfate content are
     still in progress.  Plans for the immediate future call for aerosol sampels to
     be analyzed for total sulfur at EPA using X-ray fluorescence and liquid ion
     chromatography.  A portion of each sample will also be analyzed at Calspan
     using the barium perchlorate titration technique.

          9.   Auto exhaust + S02 and in-cloud S02 to sulfate transformation
     studies will be resumed when reliable sampling and analysis procedures are
     developed and verified.

6.   Publications, Presentations and Theses:  None.

7.   Plans:

     1.   To study reaction rates of sulfur dioxide with auto exhaust and water
     droplets.
                                          15

-------
1.  Task Title:   Study of Vapor Pressures  of Systems  Forming Atmospheric  Aerosols

2.  Objective:

         To measure basic physical  properties of  certain  multicomponent  fluid
    mixtures along the equilibrium  phase  separation curves.  The  systems  chosen
    are those involved in the formation of secondary  atmospheric  aerosols,  witn
    particular emphasis on the sulfuric acid-water mixture.

3.  Institution:  Clark College, Atlanta,  Georgia
    Investigator:  G. Brown

4.  EPA Project Officer:  W.E. Wilson

5.  Progress:  The laboratory for this  project has been constructed  and  is
    essentially complete.  The apparatus  is designed  to determine the total
    vapor pressure over bulk fluid  mixtures by both capacitance manometer
    and ion gauge measurements.

         The composition of the vapor  above the bulk  mixtures  is  determined
    with the use of a time-of-flight mass  spectrometer.   If the  initial
    chemical composition of the samples is not significantly effected by
    chemical reactions, this latter measurement can be converted  to  equilibrium
    partial pressures for the various  constituents of the mixtures,  thereby
    determining the boiling- and dew-point curves for the mixtures.   The tempera-
    ture of the mixture samples is  controlled to  within  approximately 1° C  in
    the range from -60° to + io°C.

         Data are being taken on the sulfuric acid-water  system.

6.  Publications, Presentations, Theses:   None

7.  Plans:

    1.  To continue data collection and study of the  sulfuric  acid-water system.

    2.  When sufficient data on this mixture has been compiled,  to perform
        similar measurements on mixtures  containing  HC1  and HN03.
                                       16

-------
1.   Task Title:   Formation of Atmospheric Aerosols - Size Distribution
     Models for Atmospheric Aerosol,

2.   Objective:

          To develop better multimodal  models to describe the thousands of
     atmospheric size distributions  measured in the atmosphere during the
     past few years.

          To develop useful categories  for concentration, size distributions,
     etc.

3.   Institution:  University of Minnesota, Minneapolis, Minnesota
     Investigator:  K.T. Whitby

4.   EPA Project Officer:  W.E. Wilson

5.   Progress:

          Evidence from a variety of field studies suggests that atmospheric
     aerosols are in general multimodal, with two to three modes being
     observable.  The mass or volume distribution is usually bimodal with
     a minimum observed in the l-to-3-um diameter range.  The particles
     larger than a few microns originate from natural or man-made mechanical
     processes.  The mechanically produced particles are hereafter called
     "coarse particles."  The particles smaller than a few microns arise
     predominantly from condensation processes and are called "fine particles."
     The predominant man-made source of these fine particles is combustion
     or the condensation of chemical  or photochemical reaction products on
     nuclei from combustion.

          The fine particle range may also show two distinct modes.  For
     example, a trimodal size distribution was measured 30 m from the road-
     way during the GM Sulfate Study (Figure 1).  A distinct first mode was
     indicated because the source (catalyst-equipped cars) emitted most of
     the aerosol in the 0.02 ym nuclei  mode, and the accumulation mode (middle
     mode) was relatively small because the background on this day was
     very low.

          The first mode, in the vicinity of 0.02 ytn diameter, results pri-
     marily from the direct emission of primary particles from combustion.
     The second submicron mode, in the  0.15 to 0.8 ym range by volume, is
     the result of either the coagulation of primary particles or the con-
     densation of reaction products  or  water on primary particles.  The
     third mode, or coarse particle  mode, consists of mechanically produced
     aerosols with the upper size limited by classification due to sedimenta-
     tion.  There appears to be very little exchange of mass under most
     conditions between the fine and coarse particle ranges in the atmosphere.

          Most mass is inserted in the  distribution either through the
     accumulation mode or through the coarse particle mode.  Only under
     unusual circumstances near large sources of combustion aerosol (such as
     a freeway, or in a plume from a stack) is appreciable mass injected
     directly into the nuclei mode (Figure 2).
                                   17

-------
Size Distribution Models for Source Related and Urban Atmospheric Aerosols

     Atmospheric volume, mass and chemical  size distributions can be fitted
by three independent log-normal  distributions.

     This procedure has been applied to a large number of size distributions
measured with the Minnesota Aerosol Analyzing System (MAAS),   After examininq
this data in some detail, the distributions were grouped into six categories
(Table I):

Clean Background
Observed only in large clean air masses
Several hours away from combustion sources
No nuclei mode
VAC < 2Mm3/cm3

Average Background
Mixture of Clean Background, small amounts  of aged urban plumes and local
  combustion aerosol
Small nuclei mode
VAC a 5um3/Cm3
VCP independent of VAC and dependent on local sources of dust

Background + Aged Urban Plumes
Average Background + a strong plume from a  major urban area
Small nuclei mode determined by local combustion sources
VAC similar to that in an average urban area
VCP determined by local sources of dust

Background + Local Sources
Strong local combustion sources increase VAN to the urban concentrations
   of = 0,6 without much increase in VAC over background
Distribution is very dependent on nature of sources

Urban Average
Nuclei mode determined by local  sources, primarily automobiles
Accumulation mode determined primarily by aged aerosol from the general
  area; VAC = 30 on the average
Coarse particle mode determined by local sources

Urban + Sources
Strong local sources of combustion aerosol, (e,g, automobiles) increase both
  nuclei and accumulation modes
Coarse particle mode is influenced by the nature of the source: fine particle
  and coarse particle sources are usually unrelated
Concentration is widely variable in time

     The size distributions for which the parameters are tabulated in Table I
are plotted in Figure 3 and 4,  A typical size distribution measured in the
Labadie coal-fired power olant plume, located in St, Louis, is also shown
in Figure 4.  Although both background and  plume aerosol distributions usually
have small nuclei and coarse particle modes, most of the aerosol mass is in
the accumulation mode.
                                 18

-------
     Except for the clean background and Labadie plume distributions, the
volume of aerosol in the coarse particle mode is relatively constant at
about 30 ym3/cm3 (Table I, Figure 3,4).  The accumulation mode volume is
more closely related to anthropogenic contributions than is the coarse
particle mode.

     The nuclei mode is an indicator of close (less than 1/2 hour transport
time) sources of combustion aerosol except in those cases where photo-
chemically produced nuclei may be observed in relatively clean air (e.g.,
small accumulation mode).  Number concentrations of about 105/cm3 of nuclei
of size less than 0.01 ym have been observed in the Labadie plume during
the summer of 1976, which are apparently due to homogeneous reactions in the
plume.

     The formation rate of new nuclei in a coal-fired power plant plume is
only about 3.5 nuclei per cm3-sec.  These nuclei contained an insignificant
amount of mass compared to the mass that condensed directly on the particles
in the accumulation mode during the aerosol growth in the same plume.

General Mode Characteristics of the Physical Size Distribution

     From modal characterization of the variety of aerosol size distributions,
the following general conclusions have been reached:

1.   Nuclei mode.  For very fresh combustion aerosols from clean combustion
(e.g., along a freeway), the geometric mean diameter by number (DGN) is about
0.01 ym.  For more aged aerosols, DGN may approach 0.02 ym.  The geometric
standard deviation (SG) is usually between 1.5 and 1.7.  Except for well-aged
aerosols (e.g., away from sources on the earth's surface or well above the
earth's surface), the nuclei mode accounts for most of the aerosol number and
hence the Aitken nuclei count.

2.   Accumulation mode.  Average geometric standard deviation by volume (SGV)
=2.0 and average geometric mean diameter by volume (DGV) = 0.34 ym.  Also,
aged aerosols have a somewhat greater SGV than fresh aerosols; the range
being from 1.8 for fresh aerosols to 2.2 for well-aged aerosols.  In
well-aged aerosols the nuclei mode disappears into the accumulation mode by
coagulation and then the Aitken nuclei count becomes equal to the number
of particles in the accumulation mode within the experimental error of the
measurements (about + 30%).  This situation appears to be the normal condition
at altitudes greater than about 200 m, and at the surface more than 30 km
from sources of combustion aerosol.

3.   Coarse particle (CP) mode.  The average geometric standard deviation by
volume of the coarse particle mode (SGV) = 2.3, and the average geometric
mean diameter by volume (DGV) = 5 ym.  The log-normal distribution parameters
are more variable for the coarse particle mode than for the accumulation and
nuclei modes; values of DGV having been observed between 3.5 and 25 ym.  The
mass concentration in the CP mode varies from a few to several hundred yg/m3.

     An examination of the relationship between the volume of coarse particles
(VCP) and the geometric mean size of the coarse particle mode (DGVCP) shows
that DGVCP is nearly constant up to VCP = 30 ym3/cm3 and equal to about 5 ym.
Above 5 ym, DGVCP increases linearly with VCP.
                                   19

-------
6.   Publications, Presentation.  Theses:

     1.    Whitby, K.T.   Modeling  of Atmospheric  Aerosol  Size  Distribution.
     Report on Grant #R800971,  Sampling and Analysis  of  Atmospheric  Aerosols.
     Submitted to:  Atmos.  Aerosol  Res. Sec.,  Div.  of Chem. and  Phys.,
     Air Pollution Control  Office,  Environmental  Protection Agency,  May  1975.

     2.    Whitby, K.T.  and  B.K. Cantrell.   Size  Distribution  and Concentra-
     tion of Atmospheric Aerosols.   Presented  at:   82nd  Annual Meeting  of
     the AIChE, August 30,  1976.

     3.    Whitby, K.T.   Physical  Characterization  of  Aerosols.   Presented
     at:  8th Materials Research  Symposium, National  Bureau of Standards,
     September 21, 1976.

7.   Plans:

     1.    To develop modal  parameters  using the  latest data bases:   the
     1975 EPA trailer data  from Glasgow,  MO, the 1975 St.  Louis  urban
     plume data, and the 1976  Labadie  power plant  data.

     2.    Improved fitting  procedures  are being  developed  that can  be used
     as  part of a routine data  reduction  package.
                                     20

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                              O1 NILFORO PROUJNG GROUNDS
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                            LECTRICAL AEROSOL ANAUYZER>
                                              DP(/lm)
Figure 1.  Trimodal  volume distribution measured 30 m from the roadway
            during  the General Motors  Sulfate Study, October,  1975.   The
            bars are  actual data.   Solid lines are the fitted  log-normal

            distributions.
                                    CHEMICAL CONVERSION
                                    OF GASES TO LOU
                                    VOLATILITY VAPORS
                                          *
                                                     I
                                    CONDENSATION GROWTH
                                      OF NUCLEI
                                     PARTICLE DIAMETER, MICROMETER
                 TRANSIENT NUCLEI OR.
                 AITKEN NUCLEI RANGE
                      ACCUMULATION
                        RANGE
                            -FINE PARTICLES
                                   MECHANICALLY GENERATED
                                     AEROSOL RANGE
                                                            COARSE PARTICLES
 Figure 2.  Schematic of  the principal mechanisms  of  formation  and

             removal  of a  trimodal atmospheric  aerosols  size  distribution.

-------
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                 I              T
           .BACKGROUND AEROSOLS

             	 Urban Plume Influenced

             	Background Average
             	Auto Influenced
             	 Clean Background
    Q.
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Figure 3.  Volume size distributions of four background model aerosols.

           Note that except for  the CLEAN BACKGROUND,  the volume in the

           coarse particle mode  is about the same.
                     70 —




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 URBAN AEROSOLS

	 Urban

	Urban Auto
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	 Lobadie Power
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                                 Urban
                                       .abadie Plume
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                                            Influenced

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Figure  4.   Volume size distributions of two model urban aerosol distributions
            and a typical  size distribution measured in the plume  of the Labadie
            coal fired power plant on 8-14-1974,.   The power plant  plume has only
            the accumulation mode.

-------
1 •   Task Title:  Aerosol  Dynamics.

2.   Objectives:

         To study theoretical  aspects  of aerosol  phenomena and develop a compre-
    hensive model for the evolution of the size and composition distributions of
    the atmospheric aerosol.

3.   Institution:   University  of Texas, Austin,  Texas
    Investigator:  J.R,  Brock

4.   EPA Project Officer:   J.L.  Durham

5.   Progress:

         The various rate processes which alter the composition and concentration
    of urban particulate  matter may be summarized by the following relationships:
   (rate of change in  }          /rate of change due)     (rate of change
   Jcomposition of somes  =  -    [to advection      J   + *to convection and
   Ssize fraction of   I                                    [^dispersion
   Durban aerosol     J                                                      •
-------
with deposition processes appearing as boundary conditions.  Episode conditions
are marked by well  defined mixing heights and small, cyclical  advective drainage
flows.  This permits a volume averaging procedure for eq. (2)  in which dis-
persion and dry deposition appear explicitly in a lumped parameter for removal
rate.  The small, cyclical drainage flows suggested also the feasibility of a
Lagrangian cell method in the simulation.

    The input and transport of aerosol in a single cell was studied as it
traversed the urban and surrounding areas of Denver at the rate of the drainage
flow,.  Fig. 1 presents the moments (mass concentration, number concentration,
and  scat) of the calculated size distribution of the Denver aerosol for a
two-day wintertime pollution episode as described by the volume average of eq. 2
in which the cell begins its traverse at Denver's southern edge.  In the
calculation of bscat, the refractive index of the aerosol at 500 nm is taken
as (1.55-0.221).

    A marked diurnal variation can be seen during the first day with a rapid
decrease in the evening hours as the cell moves out of the city by following
the drainage flows down the Platte River valley.  Flow reversal the next day
allows transport of the cell (now containing aged aerosol) once again over the
city with resultant build-up of aerosol concentration.

    The values of the various moments in Fig. 1 are all within the range of
experimental observations.  Thus, these quantities are all based through eq. (2)
on independent estimates of the primary source emission rates.  Figure 2
shows the mass density function at 12-hour intervals.  Again the bimodal
forms, the quantitative variation of the density function, and the locations
of modes and saddlepoint are in apparent agreement with typical episode measure-
ments for the various times (cell locations) shown.  The presentation of the
rate distributions of the various processes in Fig. 3 illustrates the power of
a rigorous numerical model of the atmospheric aerosol.  The importance of all
the processes - coagulation, condensation (in this case sulfuric acid resulting
from the ozone-olefin-S02 reaction), deposition, primary source input - may
easily be studied in terms of their rates in the growth equation.

    The fine particle mode grows mainly by coagulation and primary source
input and is diminished by deposition (Fig. 3).  The coarse particle mode
grows mainly by primary source input with a minor contribution from coagulation
(turbulent, gravitational, and Brownian coagulation are all considered), and
is strongly diminished by deposition.  Although this model represents a large
simplification of typical episode conditions, it provides valuable insight into
the aerosol  dynamics.  It has provided useful predictions about the mechanisms
of particle growth and visibility effects discussed elsewhere.

    The volume average of eq. (2) has been used to explain why the mass density
functions of urban aerosols are multimodal.  Apart from the explanation based
on two major size classes associated with primary source inputs, we wished to
determine if multi-modality could result from other processes  as well  (Figs.
4, 5 and 6).  Fig.  4 indicates the test mass density function  resulting from
elimination of all  aerosol processes except input of primary sources which
were purposely chosen to give the uniform mass density functions displayed.
Fig.  5, showing a sharply peaked unimodal  function, results from addition of
the processes of coagulation and dry deposition to the primary source  input
of Fig. 4.  Finally, a marked bimodal from results if condensation with Kelvin
cut off, coagulation, dry deposition and primary source input  are all  included
in the evolution equation (Figure 6).  Primary-source size distributions, modified
                                      25

-------
    by coagulation and deposition,  undoubtedly are  the  principal  causal  agents in
    the production of the currently reported  multimodal  densities (Figure 2).
    However, additional  hither to unobserved  modes  may  exist for  the atmospheric
    aerosol  owing to secondary aerosol  production,  particularly  in  those cases
    where condensable substances  and aerosol  form a "pollution cloud"   (Figure 6)


6,   Publications, Presentations,  Theses:

    1,  P.B. Middleton and J.R, Brock.   1976,   Simulation  of Aerosol  Kinetics.
    J. Colloid and Interface Sci.  59:249.

    2.  J.R. Brock,   1974.  Repartition de  la Charge d'Espace aer Voisinage
    d'un  Faisceau de Particules.   C.R.  Acad Sc.  Paris 287.

    3.  J.R. Brock and W.H.  Marlow,  Charged  Aerosol Particles and  Air Pollution.
    1975.  Environ.  Letters.  10:53-67.

    4.  W.H. Marlow and  J.R. Brock.  1975.  Unipolar Charging of  Small  Aerosol
    Particles.  J. Colloid and Interface Sci.   50:32-38.

    5.  P.B. Middleton and J.R. Brock.   Studies  in  Aerosol  Dynamics:   The Denver
    Field Study Symposium.  Environ, Monitoring  Series.   EPA,

    6.  Middleton, P.B.  and J.R.  Brock.  1976.  On  the  Multimodality of Density
    Functions of Pollutant Aerosols.  Atmos,  Environ. 10.

    7.  P.B. Middleton and J.R. Brock.   Dynamic  Model for  Urban  Particulate
    Pollution.  Submitted to:  Atmos.  Environ.

    8.  Brock, J.R.  and  R. Drake.  Coagulation of Aerosols.  Symposium on Aerosol
    A Science and Technology.  Natl. A.I.Ch.E. Meeting,  Atlantic  City, NJ,
    August,  1976.

7.   Plans:

         1.   Complete the computer program  to permit atmospheric  aerosol
    simulation for very general meteorological conditions  directly according
    to eq.  (2).  The first application of  this  program will be  the simulation
    of the aerosol growth processes for the city of Phoenix to permit testing
    of various control strategies.

         2.   To permit the solution of eq.  (1) for the  composition distribution
    of the atmospheric aerosol.  This will  permit us to simulate  the chemical
    transformations which occur in the atmospheric aerosol.
                                     26

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               24      36
              HOURS

        NUMBER, CC~' X 10*  o
        MASS, GRAMS X 10""  +
        BSCAT, I/CM X IO'7  *
                                          Figure 1.  Moments of  calculated
                                                     size distribution  of
                                                     Denver aerosol for a two
                                                     day wintertime pollution
                                                     episode in  Lagrangian cell
                                                     traversing  city with
                                                     cyclical  drainage  flows.
                                          Figure  2.  Mass density function of
                                                     Denver  aerosol for two day
                                                     wintertime pollution episode
                                                     in Lagrangian cell travers-
                                                     ing city with cyclical
                                                     drainage flows.
HOO
                   10°
              DIAMETER, U,M

             TIME 1200 HOURS

       DISTRIBUTION,  P_C/CC

       TOTAL RATE ,
       COAGULATION

       DEPOSITION ,
       SOURCES,
PG/CC-ScC X 10 '

PS/CC-SEC X I0"!
            *•
PG*:C-SEC x io"=  x
PGAX-SEC X I0~9  X
/-,-s
                                          Figure  3. Rate  distributions of
                                                     various processes  shaping
                                                     size  distribution  during
                                                     two day wintertime pollution
                                                     episode for city of Denser.
       CONDENSATION, °G/CC-SEC X 10
                          -8
                                    27

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1.  Task Title:   Biogenic Emission  of  Aerosol  Precursors

2.  Objective:

         To determine the contribution of  naturally  occuring bacterial  sources
    to the total  atmospheric sulfur load.   Select monitoring sites  showing
    good promise  of biogenic sulfur production with  a  "clean"  reference site
    nearby.

         To monitor atmospheric sulfur levels  at selected  sites  along with
    meteorological  data.   (Wind speed, wind direction  and  temperature).

         To correlate sulfur levels with natural cycles  (tides,  day/night
    and seasonal).

3.  Institution:   EPA-ERC, ESRL-ARB
    Investigators:   L.L.  Spiller; N. Schmidt,  Gilles Kay,  G. DeJong,
                    R. Reardon, G.  Namie.  (student  aids)

4.  EPA Project  Officer:   W.E.  Wilson

5.  Progress:

         (a)  A  method of collection of volatile sulfur  compounds  using
    selective filters treated with  various silver salts  and  (OH-)  anions
    was tested for temperature and  humidity effects  on collection  efficiency.
    AgNOs treated filters were selected for H2S absorbtion and Li OH treated
    filters for  S02 absorbtion.  X-ray fluorescence  is used  for  analysis.
    (b) Further  laboratory testing  will be done on  these filters to determine
    performance  limits regarding air temperature,,  humidity, flow  rate,
    selectivity,  and sulfur load extremes  and  to compare XRF non-destructive
    analysis with other destructive wet methods of  higher  accuracy but  greater
    costs.  (D.F. Natusch Method),   (c) Design instruments  and  interface
    circuitry to support environmental studies anticipated in  the  near  future.
    Future tests  will be made at selected  sites using  a  higher flow rate for
    shorter sampling time or, a much more  accurate  analytical  method must  be
    used.  Currently we are using XRF  with measurements  at .06 um/cm2 or ,46  ppb.

6.  Publications, Presentations, Thesis:

         Presented before the Division of  Environmental  Chemistry, American
    Chemical Society.  New Orleans, LA, March  20-25, 1977.  Biogenic
    Sulfides in the Atmosphere Over a  North Carolina Tidal Marsh.

7.  Plans:

         To develop specially treated  filters  to  selectively absorb different
    volatile sulfur compounds.

         To collect laboratory data on:  collection efficiency,  effects of
    temperature, humidity, various  volatile sulfur  selectivities,  and  ease
    and accuracy of analysis at low levels.

         To develop a field collection system with  high  portability.
                                      28

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1.  Task Title:   Metal Sulfite Complexes

2.  Objective:

         To determine the existence and kinetices  of metal  sulfite  complex
    formation.

         To devise methods for the determination of these complexes  if
    they are found to exist.

3.  Investigator:  D. Lawinq  (Student Aide)

4.  EPA Project Officer:  J.L. Durham

5.  Progress:

         Initially, the metal  salt studied was  FeCl- in solution with
    Na2$0    The resulting solution was analyzed spectrophotometrically
    over a wavelength range of 600-400 nanometers.  The complex, if
    formed, could not be isolated from the ionized species  with this
    method.

         The next metal used  was Copper in the  form of CuCl2» Cuprous
    Chloride.  Literature research indicated that such a suffite complex
    would break down due to hydrolysis in neutral  solutions.   To
    present this from happening, HC1 was added  to the solutions at
    a molar concentration equal to the SO- concentration.

         The absorption spectra still revealed  no well-defined peaks
    from 800 to 200 nanometers.  Oxidation of the Copper ion  was one
    possible explanation of the transience of any complex formed.

6.  Publications, Presentation, Theses:  None

7.  Plans:

         To undertake similar experiments with  vanadium salts.
                                 29

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              A.   ATMOSPHERIC PROCESSES AND EFFECTS
     2.    Aerosol Characterization and Sources.   The utilization of physical
properties, elemental and chemical analyses, and microscopy for the charac-
terization of atmospheric aerosols and the use of this information to
determine the primary and secondary source contributions to urban pollution..
   Funded by USEPA, ORD, OALWU.  Program Element 1AA603 and 1AD712.
                                  30

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1.    Task Title:   Sources and Trace Metals in Urban Aerosols

2.    Sub-Task Title:   Urban, Non-urban,  and Marine Aerosol  Studies.

3.    Objectives:

          Apply developed sample collection and PIXE analysis techniques
     to studies on urban, non-urban, and marine aerosols.

4.    Institution:    Department of Oceanography, Florida State University
                    Tallahassee, Florida  32306
     Investigator:  John W.  Winchester

5.    EPA Project Officer:  Ronald K. Patterson

6.    Progress:

          Under this sub-task title eight major studies were  performed.
     Each study used the Florida State University Tandem Van  de Graaff
     Accelerator and Proton  Induced X-Ray Emission to analyze for trace
     elements in collected aerosols.
          Study 1.   Size fractionated aerosols,
                    in St. Louis during August,
were collected
study show that:
using the Battelle
1973.  The results
impactor,
of this
          1.   Particle size distributions of S, Cl,  K.  Ca, Ti,  V,  Mn,  Fe,
          Cu, Zn, Br, and Pb can be measured in samples  from 0.7 m^ of  air
          collected over 12-hour intervals at 1 liter/min flow rate, with
          precision of single analyses generally 10-30%, except  near the
          nanogram detection limit.
          2.   Some elements, e.g.  Ca, Fe, Ti,  K, show a tendency for
          highest concentrations in air measured in  largest particle size
          fractions, and the pattern of distribution  of  concentration with
          size is relatively invariant.  Predominantly dispersion source
          processes may account for their entry into  the atmosphere.
          3.   Other elements, e.g. S, Pb, Zn,  have  substantial  proportions
          of their atmospheric concentrations on smallest particles and
          show greater variability  in particle  size  distribution patterns,
          suggesting aerosol formation processes of  vapor condensation  at
          high or low temperatures.
          4.   During 16-22 August  1973 an atmospheric change occurred
          from a period of low speed and mostly southerly air flow, with
          evident haze and air pollution, to higher  speed and westerly
          shifting to easterly air  flow, with improved visibility and air
          quality.  The change was  associated with drops in concentrations
          of Ti, Fe, Ca, K, and S but not Zn or Pb at the south  site.and
          Ti but not the other elements at the  central site.  Transport of
          air pollution from industrial sources south of the city is indicated.
          5.   The central site showed diurnal  variations during the first
          period where concentrations of Ti, Fe, Ca,  K,  and S were  higher
          in samples taken from midnight to noon than in those from noon to
          midnight.  Variations were greatest for intermediate sized particles.
                                  31

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     Study 2.  Time sequence samples, using the Jensen-Nelson "Streaker,"
were collected simultaneoulsy at 25 sites in St. Louis during August,
1975.  From this study, correlations of elemental  concentrations in
the air with time (2 hr. resolution) and location, plus inter-element
time correlations at a single site, inferences can be made about the
transport of elemental constituents from pollution and natural sources,
as well as gas-to-particle transformations of certain elements, such
as sulfur.

     Study 3.  Fractionated aerosols were collected in north Florida
by using a Battelle impactor.  Size-specific aerosol  removal processes
can be evaluated by sampling urban, forest, and coastal locations, and
by choosing approximately 48-hour sample-averaging intervals.

It was found that elements contained in the largest particles, especially
those of >4ym, display the greatest degree of average concentration
difference between sites, a result suggesting short atmospheric residence
times and the importance of local dispersion sources  and atmospheric
cleansing processes in regulating the particle concentrations in air.
Elements contained in particles of <2ym diameter showed little average
concentration difference between sites unless they were regulated by
large-scale sources and transport processes.  Sulfur in the smallest
particles showed a marked constancy of concentration, but it may be
modified in the largest particle size ranges in relation to proximity
to the seacoast.  No evidence was found for dependence of particulate
sulfur concentrations on local pollution sources.

     Study 4.  Size fractionated aerosols were collected in Miami,
Florida.  Miami provided an opportunity to observe elemental con-
stituents of the aerosol as it may be modified from the predominately
marine atmosphere background by urban nonindustrial activity.

Major sources of the elements are the tropospheric land-derived particles
and added sea spray particles carried by prevailing southeasterly
winds, soil dust constituents raised by human activity in the city,
automotive emissions that contain lead and halogen elements, and
emissions from stationary combustion sources that include oil- and
gas-fired power plants and refuse incinerators.

This study was undertaken to evaluate the relative importance of these
major sources for 14 elemental constituents.

     Study 5.  A data set from Bermuda, consisting of ten size frac-
tioned distribution measurements of marine aerosol, was used in a 2-
component model to resolve tropospheric from sea surface derived trace
elements.

     Study 6.  Samples were collected in Bolivia, central Brazil, and
Argentina, using Battelle cascade impactors, Jensen-Nelson "Streakers"
and total particulate filters.  These samples were collected for
comparisons with data from the North American continent and for use in
transport models.
                              32

-------
          Study 7.   As  an example  of the  application  of  the  PIXE  analysis
     technique to the study of sulfur and related  trace  elements  from
     non-urban locations, comparisons were made  between  results from a
     remote continental  station in the Southern  Hemisphere,  Chacaltaya
     Mountain, near LaPaz, Bolivia, and a mid-ocean station  in  the  Atlantic
     of the Northern Hemisphere,  at Bermuda.   Size fractionated samples
     were collected at  both sites.

          Study 8.   Biased data set averaging  has  been used  to  examine
     aerosol elemental  composition data for air  mass  directional  effects.
     Samples collected  in north Florida during spring and summer  1973
     were influenced by local  and  remote  continental  sources and  additionally
     by maritime sources when  air  flow was southerly. Judgements of air
     movements during the collection of 32 5-stage cascade impactor samples
     were made by examination  of daily surface weather maps, 3-hourly
     surface winds  in Tallahassee, and semi-diurnal balloon  soundings  to
     1524 meters.  Averages of elemental  abundances as a function of
     particle size, determined by  proton-induced X-ray emission,  PIXE, were
     computed for a 14-sample  set  biased  toward  marine air flow conditions
     and for a 6-sample set biased toward continental air flow, excluding
     12 additional  samples where air flow characteristics were  variable  or
     periods of very low wind  speed were  experienced. By regarding Fe to be
     of continental origin in  all  samples, qualitative indications  of
     provenance were observed.

7.    Publications:

     1.   J.W. Winchester, D.L. Meinert,  J.W.  Nelson, T.B. Johansson,  R.E.
          Van Grieken,  C.Q. Orsini, H.C.  Kaufmann  and K.R. Akselsson.  In:
          Proc.  2nd Intl. Conf.  Nucl. Methods in  Environmental Res.,
          Columbia, MO, July,  1974, USERDA Conf-740701,  pp.  385-394.

     2.   J.O. Pilotte, J.W. Nelson and J.W.  Winchester.  Application  of
          multi-station Time Sequence Aerosol  Sampling and Proton Induced
          X-Ray Emission Analysis  Techniques  to  the St.  Louis Regional Air
          Pollution Study for  Investigating Sulfur-Trace Metal  Relationships.
          In:  Proc. ERDA X and Gamma Ray Symposium,  Ann Arbor, MI, May
          19-21, 1976 (Conf. 760539).

     3.   T.B. Johansson, R.E. Van Grieken and J.W. Winchester.   Elemental
          Abundance Variation  with Particle Size in North Florida Aerosols.
          Journal of Geophysical  Research.  1976.  81:1039-1046.

     4.   K.A. Hardy, K.R. Akselsson, J.W. Nelson  and J.W. Winchester.
          Elemental Constituents  of Miami Aerosol  as  a Function of  Particle
          Size.  Environmental Science and Technology.   1976.  10:176.

     5.   D.L. Meinert and J.W. Winchester.  Chemical Relationships in the
          North Atlantic Marine Aerosol.   Journal  of  Geophysical  Research.
          (In Press)
                                  33

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     6.    L.C.S.  Boueres,  F.  Adams,  J.W.  Winchester,  C.Q.  Orsini,  J.W.
          Nelson, T.A.  Cahill and D.R.  Lawson.   Sulfur  and Heavy Metals
          in South American Urban and  Non-urban  Atmospheres.   In:   Proc.  of
          the World Meteorological Organization  Technical  Conference  on
          Atmospheric Pollution  Measurement Techniques,  Gothenburg, Sweden,
          October 11-15, 1976.   Conf.  Proc.   (In Press)

     7.    J.W. Winchester.   Sulfur and Trace Metal  Relationships in Non-urban
          and Marine Aerosols Studies  Using Proton  Induced X-Ray Emission.
          Nuclear Instruments and Methods.   (In  Press)

     8.    T.B. Johansson,  R.E. Van Grieken  and J.W. Winchester.  Marine
          Influence on Aerosol Composition  in the Coastal  Zone.  Journal
          de Recherches Atmospheriques.  1974, pp.  762-776.
8.   Plans:
          This grant is completed.   A final  report is  forthcoming.
                                  34

-------
  100
   50 .
5  so
Q.
   •to
              16'
JO1
10
                           Figure 4.  Mass density resulting
                                     from only input of pri-
                                     mary sources.  Primary
                                     sources input rates
                                     chosen to yield a
                                     rectangular density.
                                     100% units = lOOpg/cc
   100
                                            !0
                                                   Figure 5. Unimodal mass density
                                                             resulting from  input
                                                             of primary sources  of
                                                             Fig. 4 coagulation,
                                                             and deposition.
  100
   0'	-I-	II I I Illl	1	1 I I I lilt	I I  I I I i ill  I  1 I I I nil
                                                   Figure  6.  A bimodal mass density
                                                              resulting from input
                                                              of primary source of
                                                              Fig.  4 plus coagulation,
                                                              deposition, and conden-
                                                              sation, including the
                                                              Kelvin term for varia-
                                                              tion of vapor pressure
                                                              with curvature.
                   OIRHETEB. [jn

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    1.  Task Title:   Relationship of the Smog Aerosol  to Pollution Sources

    2.  Objective;

             To develop experimental  and theoretical methods  for relating the
        properties  of the pollution aerosol  to the  characteristics of emission
        sources.

    3-  Institution:   California Institute of Technology, Pasadena
        Investigator:  S.K.  Fried!ander

    4.  EPA Project  Officer:   VI.E.  Wilson

    5.  Progress:

             Homogeneous nucleation in ambient urban air was  documented by
    watching time  profiles of condensation nuclei and  carbon  monoxide before
    and after changes from daylight savings  time  to standard  time.  An increase
    in condensation  nuclei occurred soon after sunrise both before and after
    the time change,  while the CO increase tended to be shifted  an hour along with
    anthropogenic  activity;  therefore, some  homogeneous nucleation occurs soon
    after sunrise.

             Quantitative experiments were conducted using a  60  m3 Teflon reac-
    tor.  The bag  was filled with ambient air of  varied aerosol  loadings.  The
    air in the bag was doped with S02, NOX,  and propylene to  facilitate formation
    of sulfate aerosol by homogeneous gas phase reactions. Reaction rates  varied
    from 0.288 ppb S02/hour to 144.0 ppb SO^/hour by varying  the concentrations
    of reactants from near ambient  levels to levels higher than  ambient.  Experi-
    mental results  indicate that homogeneous nucleation becomes  more important
    as rates of aerosol  production  increase  and initial aerosol  loadings decrease.

             A theoretical model has been developed which predicts the relative
    amounts of aerosol accumulating on new and original particles as functions
    of time, aerosol  formation rate and amount of pre-existing aerosol.  The
    evolution of the size distribution of the initial  aerosol as a result of
    condensational  growth can also be calculated:   agreement  with experimentation
    is very good.

             The distribution of aerosol nitrate  compounds with  respect to  par-
    ticle size is  also under study.  A new technique has been developed for the
    measurement of aerosol nitrate deposited on the stages of an impactor.   The
    method has been  applied to the aerosol collected with the low pressure
    impactor at various locations in and around Los Angeles.   Preliminary
    results indicate a bimodal distribution  of nitrate with respect to particle
    size.

6.  Pub 1 i ca t_1_ons_,  P res en ta ti ons. Th es es:

    1.   Heisler,  S.L. and S.K. Friedlander, Growth Mechanisms for Urban Aerosol
    Particles.  In:   Proceedings of the International  Colloquium on Drops and
    Bubbles, California Institute of Technology-JPL.   August  1974, Vol. II, p.553.

    2.   Grosjean,  D. and S.K. Friedlander.   Gas-to-Particle  Distribution Factors
    for Organic and  Other Pollutants in Los  Angeles.   J. Air  Poll. Control  Assoc.
                                   36

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    3.    Grosjean,  D.   1975.   Solvent  Extraction  and Organic Carbon Determination
    in  Atmospheric  Particulate Matter:  The Organic Extraction-Organic Carbon
    Analyzer (OE-OCA)  Technique.   Anal. Chem.   47(6):797-805.

    4.    Roberts, P.T.  and  S.L.  Friedlander.   1976.  Analysis of Sulfur in
    Deposited Aerosol  Particles  by Vaporization and Flame Photometric Detection.
    Atmos.  Environ,  10:403.

    5.    Roberts, P.T.  and  S.K.  Friedlander.   1976.  Photochemical Aerosol
    Formation S09,  1-Heptene,  and NO   in  Ambient  Air   Environ. Sci. and Technol.
    10:573.     *                   x

    6.    Heisler, S.L.  and  S.K.  Friedlander   1976.  Gas-to-Particle Conversion
    in  Photochemical  Smog:   Growth Laws and Mechanisms for Organics  Atmos.
    Environ.  10:215.

    7.    Friedlander,  S.K.   Gas-to-Particle Conversion:  A Key Problem in Air
    Pollution.  Presented at:   The Research Directors'  Conference, California
    Institute of Technology-Industrial Associates, Pasadena, CA  April 19,  1976.

    8.    Friedlander,  S.K.   Gas-to-Particle Conversion.  Presented at:  The
    Department of Meteorology  Seminar  Series,  University of California, Los
    Angeles, CA April  21,  1976.

    9.    Flagan, R.C.  and S.K. Friedlander Particulate Formation  in Pulverized
    Coal  Combustion -  A Review  Presented at:   The AIChE National  Meeting,  Atlantic
    City, NJ  August 31,  1976.

   10.    Friedlander,  S.K.   Fundamentals  of Gas-to-Particle Conversion - A
    Review.  Presented at:   The AIChE  National Meeting, Atlantic City, NJ
    August 31, 1976.

   11.    Roberts, P.T., Gas-to-Particle Conversion:  Sulfur Dioxide in a Photo-
    chemical ly Reactive System  Ph.D.  Thesis   California  Institute of Technology,
    Pasadena, CA May 1975.

   12.    Heisler, S.L.   Gas-to-Particle Conversion in  Photochemical Smog:   Growth
    Laws  and Mechanisms for Organics   Ph.D. Thesis  California Institute of
    Technology, Pasadena, CA  July 1975.

7.   Plans:

    1.  To analyze  data and conduct additional experiments involving simultaneous
    formation of organic and sulfate  aerosols. Previous work on this grant
    indicates that  condensable organic products tend to accumulate in larger
    size  ranges than sulfates  because  of  the  Kelvin effect.  By using a low
    pressure impactor it will  be determined whether simultaneous condensation
    of  organics and sulfates results  in a larger  average size for  sulfate con-
    taining aerosols than condensation of sulfates alone.

    2.   Experiments to determine the  effect of different types of  sources
    including the marine aerosol, NO   pollution and agricultural fertilizers on
    particle size distribution will Be continued.
    3.   Low pressure impactor  data collected  durinp the Santa Monica Freeway
    Sulfuric Acid Aerosol Project will be analyzed.  The  freeway and background
    data will be compared to permit estimation of the  sulfur distribution with
    respect to  particle size in primary  automobile emissions.


                                   37

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1-   Task Title:   A Study of the Identity and Sources  of Atmospheric Aerosols.

2.   Objective:

          To develop and apply optical  and electron  microscopy procedures
     for the identification and characterization of  atmospheric aerosols.

3.   Institution:   I IT Research Institute, Chicago,  Illinois
     Investigator:  R.6. Draftz

4.   EPA Project  Officer:  J.L. Durham

5.   Progress:

     1.    In November 1975, I IT Research Institute and the EPA conducted an
     airborne dust sampling study in Maricopa County,  AZ, to  characterize the
     types and sources of suspended dust impacting on  the city of Phoenix.
     The purpose  of this study was to discover whether high suspended dust
     concentrations in the city are due to particles transported from
     surrounding  deserts or from local  sources.

          Suspended dust samples were collected with a network of hi-volume
     filters and  impactors located in and outside of Phoenix.   These fixed
     monitoring  sites were supplemented with dust samples collected with an
     EPA helicopter at heights from 30  to 500 meters.

          Dust concentrations measured  with hi-volume  filters  averaged
     200 pg/m3  for samples located 3 to 20 meters above ground level and
     130 ug/m3  for samples measured 30  to 500 meters above ground.   Therefore,
     dust concentrations decreased with height.

          The dust particles were identified by optical and electron micro-
     scopy.   The  majority of particles  contributing  to high dust concentrations
     were minerals -- feldspars, quartz, calcite, mica, and clays.   Carbon-
     aceous  particles from auto exhaust and rubber tire particles were also
     present as  minor components in every sample, even those  collected in
     sparsely populated rural areas.

          The size, composition, and concentrations  of these  particles, com-
     bined with  meteorological data, indicate that the particle sources were
     predominately local to the sampling sites.   Vehicular traffic and
     farming are  judged to be the primary contributors to the  high dust
     concentrations in Phoenix.  Particles from industrial sources were
     insignificant.

     2.    Aerosols were collected in powerplant and  urban plumes emanating
     from St. Louis, MO, during July and August, 1975.  The samples were
     collected at various distances and altitudes with an instrumented
     aircraft.   Polarized light and electron microscopy were  used to identify
     the types of aerosols formed and transported in the plume.

          Sulfuric acid or ammonium sulfate was the  major, respirable com-
     ponent found in every sample.  Minerals, flyash and a very unusual
     carbonaceous aerosol were minor components of each sample.  These samples
                                   38

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     provided the first direct evidence of sulfuric acid in urban and power-
     plants and also provided proof that they are transported at distances
     of up to 200 miles.

6.   Publications, Presentations,  Theses:

     1.   Microscopical Analysis  of Aerosols Transported from St. Louis.
     Presented at:  American Chemical  Society Meeting, New York City, NY,
     April, 1976.

     2.   Aircraft Collection and  Microscopical  Analysis of Ambient Aerosols
     from Urban Atmospheres.  Air  Pollution Control Association Meeting,
     Portland, OR, June, 1976.

     3.   Comparison of Elemental  and  Microscopical Analyses of Atmospheric
     Aerosols.  American Chemical  Society Meeting, New York City, NY,
     April, 1976.

     4.   Similarities of Atmospheric  Aerosols from Four Major U.S. Cities.
     Eighth Aerosol Technology Meeting, Research Triangle Park, NC, October,
     1975.

     5.   Morphology of Airborne  Dust  in Maricopa County, Arizona.   In
     preparation for presentation  at:   the 1977 AAAS Symposium on Denver
     Dust, Denver, CO, February,  1977.

7.   Plans:

     1.   A new filter/impactor substrate has been discovered which may permit
     non-destructive analysis of  atmospheric aerosols by microscopy, X-ray
     spectroscopy and chemical analysis.  The present substrates are not  com-
     patible for all analyses, therefore increasing the number of samples  that
     must be collected to obtain  a reliable and complete characterization  of
     aerosols.  Laboratory tests  and limited field trials will be performed
     to evaluate the suitability  of this substrate for multiple non-destructive
     analyses.

     2.   Microscopical image analysis will be developed to permit quantita-
     tive measurement of aerosol  size  and concentration for total samples,  as
     well as for individual  particle types within a sample.  Polarized light,
     UV fluorescence, dispersion  and chemical staining by optical microscopy
     will be explored as methods  to enhance aerosol discrimination and detection.
     Backscattered electron and micro  X-ray emission imaging will be applied
     to submicron aerosols as a means  of performing particle size by aerosol
     type.
                                   39

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1.  Task Title:  Analysis of Air Pollutants by Mass Spectroscopy.

2.  Objective:

         To examine the usefulness of high-resolution mass  spectroscopy without
    prior chemical separations in determining the composition  of the organic
    portion of the atmospheric aerosol.

         To investigate the composition  of real  aerosol  samples at various urban
    sites.

3.  Institution:  University of Washington, Seattle, Washington
    Investigator:  A.L. Crittenden

4.  EPA Project Officer:  R. Patterson

5.  Progress:

         High-resolution mass spectroscopy was shown to  be  a useful  means of
    characterizing the organic fraction  of the urban aerosol.   Quantitative
    accuracy was limited, particularly  for compounds of  low abundance.  Some
    ambiguities were found in the assignment of origins  of  ions formed in the
    mass spectrometer.

         Major constituents of fine particles in urban atmospheres are sulfuric
    acid or sulfates, and hydrocarbons.   Other compounds that  can  be detected
    include phenols, aromatic carboxylic acids (and possibly esters) and aliphatic
    dibasic acids.  Evidence was found  of several other  difunctional compounds,
    including nitrate or nitrite species.

         Strong evidence was found for  the presence in some urban  aerosols of
    compounds reported by others as products of the oxidation  of toluene in
    smog chamber reactions.  Less evidence was found for products  of the
    oxidation of terpenes.

         A few samples of automobile exhaust particulates have been analyzed.
    The occurrence of benzoic acid and  the benzol ion in mass  spectra appear to
    be possible indicators of automotive contribution to the organic components.

         Results for a large number of  compounds are provided  for  88 aerosol
    samples collected at sites located  in the greater Los Angeles, Seattle,
    St. Louis and Denver Areas.

6.  Publications, Presentations, Theses:

    1.  Crittenden, A.L.  Analyses of Air Pollutants by  Mass Spectroscopy.
    EPA-600/3-76-093, U.S. Environmental Protection Agency, Research Triangle
    Park, NC, 1976.  287pp.

    2.  Schuetzle, D., A.L. Crittenden  and R.J. Charlson.  1973.  Application
    of Computer Controlled High Resolution Mass Spectrometry to the Analysis
    of Air Pollutants.  J. Air Poll. Control Assoc.  23:704.

    3.  Schuetzle, D., D.R. Cronn, A.L.  Crittenden and R.J. Charlson.  1975.
    Molecular Composition of Secondary Aerosol and Its Possible Origin.  Environ.
    Sci. Technol.  9:838.
                                      40

-------
    4.   Knights,  R.L.,  D.R.  Cronn  and  A.L.  Crittenden;   Diurnal  Patterns  of
    Several  Components  of Urban Participate Air Pollution.   Presented  at:
    The Pittsburgh Conf.  on  Analytical  Chemistry and  Applied Spectroscopy,
    Cleveland,  OH, March  1975,

    5.   Cronn,  D.R.   1975.   Analysis of Atmospheric Aerosols by  High-Resolu-
    tion Mass Spectrometry.   Thesis  to be  submitted to:   University  of Washington,  WA.
7.   Plans:
         Project terminated and reported  in:

    Crittenden, A.L.   Analysis  of Air Pollutants  by  Mass  Spectroscopy.   EPA-
    600/3-76-093, U.S.  Environmental  Protection Agency,  Research  Triangle
    Park, NC, 1976.   287pp.
                                      41

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1.  Task Title:  Chemical  Characterization of Model  Aerosols

2.  Objective:

        To identify the molecular structure of components  of  aerosols formed
    from individual hydrocarbons under simulated atmospheric  conditions,

        To relate aerosol  constituents to the type of  aerosol  precursor and
    chemical reaction.

3.  Institution:  Battelle-Columbus Laboratories, Columbus, Ohio
    Investigators:  David  Mendenhall,  P.M. Jones, C.J.  Riggle, A.D.  Graffeo,
                    D.F. Miller, W.E.  Schwartz

4.  EPA Project Officer:  R.K.  Patterson

5.  Progress:

         Model aerosols were generated by irradiating  individual  hydrocarbons,
    toluene and 1-heptene  in air in the presence of NOX or NOX/S02-   The  collected
    aerosols were subjected to  analysis by mass spectrometry  and chromatographic
    techniques, both with  and without  chemical derivatization.  The  organics
    associated with the vapor phase were collected with a  chromatographic adsorbant
    trap and analyzed by gas chromatography with mass  spectrometric  detection.

         The organic species associated with 1-heptene  aerosol reaction products
    were tentatively identified as n-hexaldehyde, cyclohexanol (or an n-hexenol),
    and'1-heptene epoxide.   The aerosol from 1-heptene  revealed over 130  peaks
    on direct mass spectral  analysis in a heated probe  (Figure 1).   The high
    molecular weight products are evidently formed by  condensation  of fragments
    from individual 1-heptene molecules.

         The gas-phase  species  from toluene include compounds tentatively iden-
    tified as simple transformation products of the hydrocarbon (Figure 2).
    Analysis of the aerosol  from toluene, after derivatization with  a trimethyl-
    silylating reagent, revealed a number of more highly oxidized products whose
    structures were inferred from m/e  values of their  parent  ions (Figure 3).

         The products observed  had undergone little or no  oxidative  degradation,,
    and a considerable  degree of ring  substitution had  taken  place.   Minor
    differences were observed between  toluene/NOx and  toluene/NOx/S02.   No
    organic sulfur-containing compounds were detected.   All major products were
    common to both experiments.  Of the nine major products - Benzaldehyde,
    Nitrophenol, Nitrotoluene (3 isomersLand Nitrocresols (4 isomers); eight
    contain a nitro group.

         In the toluene/NOx/S02 system, an additional  major product  formed which
    appears to be a polar  compound of molecular weight  122.   This compound doesn't
    contain sulfur, and its mass spectrum is consistent with  that of methyl-p-
    benzoquinone, but has  not been verified with a standard.

         The Ames test  for mutagencity was carried out with  unfractionated
    aerosols from both  1-heptene and toluene.  No carcinogenic properties were
    revealed in any of the aerosol samples tested.
                                       42

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6.  Publications, Presentations,  Theses:

    1.   G.D.  Mendenhall,  P.M.  Jones,  A.P.  Graffeo,  W.E.  Schwartz  and  W.E.  Wilson.
    The Composition of Certain Atmospheric Aerosols,   In:   171st  American  Chemical
    Society Meeting, New  York, NY,  April  1976.

    2.   W.E.  Schwartz, P.W.  Jones,  D.F.  Miller  and  G.D.  Mendenhall.   Organic
    Composition of Model  Aerosols.   California   Air Environment.   In  Press.

7.  Plans:

    The project has been  terminated and  reported in:

    Schwartz, W.E.  Chemical  Characterization of Model  Aerosols.   EPA-650/3-74-011
    U.S.  Environmental Protection Agency,  Research  Triangle Park, North  Carolina.
    1974.  130pp.

    Schwartz, W.E., G.D.  Mendenhall,  P.W.  Jones, C.J.  Riggle,  A.P. Graffeo and
    D.F.  Miller.  Chemical  Characterization of  Model Aerosols.  EPA-600/3-76-
    085,  U.S. Environmental  Protection Agency,  Research Triangle  Park, North
    Carolina.  1976.  80pp.
                                        43

-------
                                                           "11' i' i'
         60 80 100 20 40  60 80 200 20 40 60 80 300 20  40 60 80 400 20 40 60  80 500 20 40 60 80 600
                                       M/E
   FIGURE  1.  CHEMICAL IONIZATION MASS SPECTRUM  OF 1-HEPTENE AEROSOL
                 (SAMPLE  M599).   SUCCESSIVE SPECTRA RECORDED  AS PROBE
                TEMPERATURE  RAISED FROM 25 TO 200  C
100-

90-

80-

TO-
30-

20-

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 0
                                                                     TOLUENE/NO,,
                                                                     VAPORS
     10  20  30  40  50
     Spectrum Number
                    60  70  80  90  100 110 \2Q 130 140 150  160 170 180 190 300 210  220 230 240 250 260 270
   FIGURE 2.   METHANE IONIZATION GC-MS ANALYSIS OF  VAPOR PHASE
                ORGANIC COMPOUNDS ASSOCIATED WITH TOLUENE/NOx
                AEROSOL
                                     44

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1.  Task Title:  Sources and Trace Metals in Urban Aerosols.

2.  Sub-Task Title:  Aerosol Properties Relavent to Health  Effects.

3.  Objectives:

         Design experiments which apply sensitive X-Ray analysis techniques to
    the measurement of aerosols related to human respiratory  uptake  and deposition,

4.  Institution:  Department of Oceanography, Florida  State University
    Investigator:  John W.  Winchester

5.  EPA Project Officer:  Ronald K.  Patterson

6.  Progress:

         The particle size  distribution of lead, bromine, chlorine and calcium
    in exhaled aerosols from a human subject breathing normally polluted air
    was measured using proton induced X-Ray emission (PIXE) analysis.   This
    experiment in the respiratory deposition of aerosols utilized two  similar
    air sampling devices, one for sampling the ambient air  directly  and one
    into which the subject  supplied  all  the air from his exhaled breath.
    Both devices were operated by a  vacuum pump which  drew  air at a  constant
    rate by means of critical flow orifices.  The sampling  devices used 5
    and 6 stage Battelle-type cascade impactors, which operated at flow rates
    of 12 liters per minute and 1 liter per minute, and gave  resolution down
    to 0.5 and 0.25 -pm diameter, respectively, on the impaction stages.  Two
    aerosol  sources were employed:  chalk dust generated by blackboard erasers
    and lead halide aerosols generated by an automobile operating at idling
    speed in a semienclosed space near the subject.  Three  experiments were
    conducted using the two sources  separately and combined.   Using  PIXE analysis
    Ca, Pb,  Br, and Cl  were easily measured in samples collected over  a ten-
    minute interval.

         Figure 1 is a plot of the apparent respiratory deposition fraction for
    calcium, lead, bromine  and chlorine.   A similar pattern is shown for all
    elements, with a minimum deposition well under 50% in the region of 0.5um
    diameter (aerodynamic equivalent for unit density  spheres) and deposition
    well over 50% for both  smaller and larger particles.  In  this study fea-
    sibility was demonstrated for direct determinations of  trace element
    respiratory depositions in human subjects breathing aerosols at  ambient
    air concentrations.

         Another study under this sub-task title utilized the data from the
    above study and a Los Angeles freeway study to calculate  the fraction of
    atmospheric lead expected to be deposited in the respiratory tract as
    a function of particle size for the upwind and downwind freeway  sites.
    The calculation indicates the qualitative finding that  differences in
    a particle size distribution combined with differences  in the efficiency
    of respiratory deposition may determine the overall magnitude of lead
    deposition by aerosol inhalation.  Emperical deposition curves for
    pulmonary, tracheobronchial, and nasopharyngial regions published  by
    the Task Group on Lung Dynamics, were used to estimate  the extent and
    location of lead aerosol deposition, based on the measured Los Angeles
    size distributions (Figure 2).  For individual upwind and downwind sites,
    respectively, total lead deposition summed over all particle sizes are


                                      46

-------
    33% and 35% for pulmonary, 5,4% and 5.7% for tracheobronchial ,  and 9.3% and
    7.5% for nasopharyngeal regions; these values do not indicate  significant
    differences in total deposition of lead with aerosol age.   However, within
    particle size classes the differences were significant, and these were
    expected to be linked with the points of deposition within the  lung.

7.  Publications:

    1.  G.G. Desaedeleer, J.W. Winchester, and K.R.  Akselsson.  Monitoring
    Aerosol Elemental Composition in Particle Size Fractions for Predicting
    Human Respiratory Uptake.  Nuclear Instruments and Methods (In  Press).

    2.  G.G. Desaedeleer and J.W. Winchester.  Trace Metal  Analysis of
    Atmospheric Aerosol Particle Size Fractions in Exhaled Human Breath,
    Environmental Science and Technology, Vol. 9, October, 1975, pp.971-972.
8.  Plans:
         This grant is complete.   A final  report is  forthcoming.
                                     47

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1.   Task Title:  Aerosol  Sources Program

2.   Objective:  To collect ambient aerosols with the goal  of identifying
                aerosol  sources through wind-directional  sampling and
                sensitive analysis techniques.

3.   Institution:  EPA, Aerosol  Research Branch

4.   EPA Project Officer:   Ronald K.  Patterson

5.   Progress:   Samples were collected in Miami, St.  Louis,and Pittsburgh
    between May and July, 1975.  Modified Battelle type samplers were
    operated by an Aerosol Research  Branch designed  wind-directional
    programmer which operates up to  four (4) selectable wind sectors
    with two degree resolution.  Florida State  University Streaker
    samplers were also used and both types of samples were analyzed
    by Proton-induced X-Ray Emission at Florida State.

         A report on the  Miami  and St.  Louis analysis results was
    prepared for OAQPS (Tom Pace) in October, 1975.   The final draft
    report on the data analysis and  interpretation of the Miami results
    is being prepared under EPA Contract #68-02-2406 by Dr. Kenneth A.
    Hardy, Florida International University.  St. Louis and Pittsburgh
    data reduction and interpretation will begin next month under the
    same contract.

6.   Publications, Presentations, and Theses:  None

7.   Plans:  Prepare reports on  St. Louis and Pittsburgh results by July, 1977,
                                     50

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1-   Task^ Title:  Aerosol Microscopy

2.   Objective:

         To carry out research studies of the structure, composition and
    sources of pollutant aerosol  particles and other environmental  studies
    that may be assigned through  the use of electron-optical  and optical
    X-ray analytical methods.

3.   Institution:  Environmental  Protection Agency, ESRL, ARB, Research
                  Triangle Park,  North Carolina.
    Investigator:  J. Gerhard

4.   EPA Project Officer:  J. Gerhard

5.   Progress:

         The following more recent tasks are completed:  Tampa Aerosol Study;
    Texas Dust Storm Study; Iron  Foundry, Utah Study; Cal-Nevada Study;
    Asbestos in Building Materials and Respiraton Filter Deposit examinations.

6,   Publications, Presentations,  Thesis:  None

7.   Plans:

         Written reports of the analytical results of all future studies
    will be distributed to all interested personnel  as expediently as possible,
                                     51

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4.

5.
    Task Title;   Field Expedition  to  Phoenix, Arizona

    Objective:

        To determine the importance of  dust transported from the surrounding
    deserts on  the mass loadings measured  in the Phoenix area,
    Institutions:
    Investigators
                   ARE -  ESRL           Jack L. Durham
                   AMAD - ESRL          Ken Scherer
                   EPA -  LV             Jeff Van Ee
                    IIT Research  Institute - Richard Snow, Jean Graf, and
                    Ronald Draftz.
                    P. Durham, J.  Frazier, and L. Quinn  (EPA student aids)
    EPA Project Officer:   Jack  L. Durham

    Progress:

        During November,  1975,  airborne and ground-level dust samples were
    collected  for the  purpose of characterizing the types and sources of
    suspended  dust impacting Phoenix.  Wind profile measurements were also
    made.
        Dust concentrations  measured with  hi -volume filters averaged 203
    for samplers  located  30  to  20 meters above ground level.  Dust concentrations
    ranged from 130  ug/m^ to 30 yg/m3 measured 30 to 500 meters above ground
    level.  The dust concentrations decreased with height.

        The dust  particles were identified by optical and electron microscopy.
    The majority  of  particles contributing to the high dust concentrations were
    minerals -- feldspars, quartz, calcite, mica, and clays.  Carbonaceous
    particles from auto exhuast and rubber tire particles were also present as
    minor components in every samples,  even those collected in sparsely populated
    rural areas.

        The size, composition,  and concentrations of these dust particles,
    combined with meteorological data,  indicate that the particle souces
    were predominantly local  to the sampling sites.  Vehicular traffic, and to
    some extent farming,  are judged to  be  the primary contributors to the high
    dust concentrations in Phoenix.  Particles from industrial sources were
    insignificant.

6.  Publications  ana Presentations:

    1.  Graf, J., R.H. Snow, J.L. Durham,  and K.L. Scherer.  Morphology of
        Airborne  Dust in  Marcopia County,  Arizona.  Presented at:  AAAS
        Meeting,  Denver,  February 1977.  To be published in Proceedings.

    2.  Suck, S., E. Upchurch, and J.  Brock.  Dust Transport in Maricopa
        County, Arizona.   Presented at  AAAS Meeting, Denver, February 1977,
        To be published in Proceedings.
    3.  Graf, J., R.H.  Snow, and R.G.  Draftz.   Aerosol
        Phoenix, Arizona.   (EPA-600/3-77-015  February,
        Institute, Chicago).  136 pages.

7.  PIans:   Project is  complete.
                                                       Sampling  and  Analysis
                                                       1977).   IIT Research
                                   52

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1.   Task Title:  Analytical  Support for Aerosol  Studies

2.   Objective:

          Provide or arrange  for the analysis of ambient aerosol  samples
     collected in the field and adapted existing analytical  analysis
     techniques to aerosol samples.

3.   Institution:  Environmental Protection Agency, Aerosol  Research Branch
     Investigator:  R.K. Patterson; Joe Frazier and Kevin Peterson(Student Aids)

4.   EPA Project Officer:  Ronald K. Patterson

5.   Progress:

          An ion chromatograph was installed and modified with an automatic
     sampling system.  This system is being used to determine the SO];, SOo,
     NO^, NOJ}, Br~, Cl~, NH^, Na+,and K+ content in ambient aerosols.

          Progress is being made on determining the organic carbon content
     of fractionated ambient  aerosols using a temperature programmable
     furnace and a flame ionization detector system.  The major setback
     in this effort has been  finding a collection medium which does not
     interfer with the analysis.

          Other analytical techniques such as Proton-induced X-Ray Emission
     and Computerized High Resolution Mass Spectrometry have been evaluated
     through grants.

6.   Publications, Presentations. Theses:  See Winchester and Crittenden grants.

7.   Plans:

     1.   Release RFP for an  "Analytical Support for Aerosol Studies" contract,
     in order to relieve our  equipment of approved routine techniques.

     2.   Continue to research our ion chromatography capabilities as they
     relate to ambient aerosols.

     3.   Continue to pursue  a suitable technique for determining organic
     carbon in fractionated ambient aerosol samples.
                                  53

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               A.  ATMOSPHERIC PROCESSES AND EFFECTS
     3.    Visibility and Radiation Effects.   Measurement of pertinent
aerosol  properties and determination of relationships between concentration,
composition, size and effects.
   Funded by USEPA, ORD, OALWU.  Program Element 1AA603 and 1AD712.
                                  54

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1.   Task Title:   Opticle Effects of Atmospheric Aerosol

2.   Objective:

          To develop experimental and analytic techniques for understanding
     sources of aerosol particles and their integral  optical  effects.

3.   Institution:   University of Washington, Seattle, Washington
     Investigator:  A. P. Waggoner

4.   EPA Project Officer:  T.G.  Ellestad

5.   Progress:

          Condensed water interacts with aerosol particles in ways that
     depend on  the molecular nature of the particles.  Using  this interaction,
     instruments were designed that measure the scattering behavior as a
     function of relative humidity to determine the molecular form of SO^
     when it is present as a major constituent of the fine particle mass.
     $04 (as H2S04 or
     US haze, and
     the time.
                            was found to dominate midcontinent rural
             was found present as acid sulfate approximately one half
     These results were obtained at a single site near St. Louis in 1973,
and at three sites in rural Michigan, Missouri and Arkansas in 1975.
An instrument was constructed to facilitate making these measurements.
The form of the sulfate aerosol (salt or acid) was shown to be related
to long range transport in that marine tropical air from South and East
was predominately acidjand air from the North and West was predominately
salt.

     The almost continuous SQq domination at all three sites indicates
that the rural haze is the product of a multitude of sources covering
an area larger than one SO^ removal/SOo oxidation distance.  These
results have direct bearing on such suojects as S0£ control via tall
stacks or via scrubbers, and the sources of rural and urban $04.

     Experimental measurements have been made of SC^ oxidation rate in
solution with Q£ and 0^ under a range of temperatures and pH.   The
study showed that the rates of conversion of S02 to $04 measured in
plumes are consistent with 03 solution oxidation rates which should
exist in warm clouds.

Publications:

1.   Larson, T.V., R.J. Charlson, E.J. Knudson, G.D. Christian and H.H.
Harrison.  1975.  The Influence of a SOo Point Source on the Rain
Chemistry of a Single Storm in the Puget Sound Region.  Water  Air and
Soil Poll.  4.

2.   Vanderpol, A.M., F.D. Carsey, D.S. Covert, R.J. Charlson  and A. P.
Waggoner.  1975.  Aerosol Chemical Parameters and Air Mass Character
in the St. Louis Region.  Science, 190: (7 Nov).
                              55

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3.   Waggoner, A.P., A.H.  Vanderpol,  R.J.  Charlson,  T.V.  Larsen,  L.
Granat and C. Tragardh.   1976.   Sulfate as a Cause of Tropospheric
Haze.  Nature.  261(13 May).

4.   Porch, W.M., D.S. Ensor, R.J.  Charlson.   1975.   Visibility of
Distant Mountains as a Measure of Background Aerosol  Pollution.  Applied
Optics.  14.

5.   Weiss, R.V., A.P. Waggoner, R.J.  Charlson,  N.C.  Ahlquist.   Sulfate
Aerosol:  Its Geographical Extent.   Science.   In Press.

6.   Bolin, B., R.J. Charlson.   1976.   On the Role of the Tropospheric
Sulfur Cycle in the Short-Wave Radiative Climate of the  Earth.   AMBIO.
5(2).

7.   Covert, D.S., R.J.  Charlson, R.  Rasmussen,  H. Harrison.   1975.
Atmospheric Chemsitry and Air Quality.  Reviews  of Geophysics and
Space Physics.  13(3).

8.   Scheutzle, D., D. Cronn, A.L.  Crittenden and R.J. Charlson.   1975.
Molecular Composition of Secondary Aerosol and Its Possible Origin.
Env. Sci. and Tech.  9(9).

Plans:

1.   To conduct field experiments in the Oregon-Washington area this
fall to define the magnitude of impact and help  identify sources  of urban
and rural aeroso^ in this region.

2.   Laboratory and field experiments are being  designed to investigate
the role of urban emissions in altering the nature and persistence of
high humidity hazes and fogs.  Data to be examined include the:  relation-
ships between the aerosol concentration of Pb, S0|,  Fe and optical
absorption to determine the source and nature of materials that may cause
heating of air aloft and altering stability; role of long range transport,
RH, temperature, incidence of rainfall along trajectory  as these  affect
S0| acid/salt character of the aerosol; character of visibility distri-
butions from airports and other sources as a function of site location
to determine the causes of reduced visibility.
                              56

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               A.  ATMOSPHERIC PROCESSES AND EFFECTS
     4.   Heterogeneous Reactions.   Measurement of the rates and mechanisms
of reactions involving gases with surfaces or condensed phases.
   Funded by USEPA, ORD, OALWU.  Program Element 1AA603 and 1AD712.
                                  57

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1.  Task litie:  The Role of Gas-Solid Interactions in Air Pollution,

2.  Objective:

         To assess the importance of heterogeneous  surface reactions of gas-
    eous pollutants such as S02 with constituents of urban aerosols and ground
    level surfaces in the urban environment,

3.  Institution:   The Aerospace Corporation,  Los Angeles,  California
    Investigator:  H, Judeikis

4.  EPA Project Officer:  J.L. Durham

5.  Progress:

         Measurements have been made on the capacities for S02  removal  over
    various solids (Table 1).   The dependency of reactivities  and capacities
    on various experimental conditions have been examined  and  surface  reaction
    products have been analyzed.  Measured capacities ranged from several
    tenths of a gram of S0£ removal  per gram  of solid for  materials such as
    MgO and MnO (particularly for humidified  reaction mixtures)-to several
    milligrams of $03 per gram of solid for materials such as  charcoal.
    Both reactivities and capacities were found to  be generally independent
    of S02, 02, and total pressures.  Reactivities  were found  to be generally
    independent of relative humidity; capacities were not.  Capacities
    measured with humidified reaction mixtures were frequently  an order of
    magnitude greater than those found for dry mixtures.   X-ray photoelectron
    (ESCA) and wet chemical techniques identified sulfate  as the only  sulfur-
    containing surface reaction product.

         Laboratory measurements have been made of  deposition  velocities for
    S02 at ground level surfaces (Table II).   The apparatus used accounts  for
    gas-phase mass transport of S02  so that obtained values are due solely to
    the physical  and/or chemical processes responsible for SO^  removal  at  the
    surface.  Here also, removal was found to accur via capacity limited
    reactions.  Results show the dependencies of reactivities  and capacities on
    S02, O^, total pressure, and relative humidity  were qualitatively  similar
    to those discribed above.

         Also examined was the potential role of additional environmental
    factors on S02 removal.  Pre-treatment of selected solids  with dilute  am-
    monia (or NaOH) was found to enhance initial reactivities  by a factor  of
    approximately 5, while pre-treatment with dilute ^804 (HC1) reduced
    initial reactivities by one order of magnitude.

         In order to remove soluble sulfates, several solids were washed with
    distilled water after their reactivity toward SO? was  completely expended
    (footnote 3 of Table 1).  This treatment  restored initial  reactivities
    within experimental error, thus suggesting that precipitation could restore
    the reactivity of ground-level surfaces in the  actual  environment.

6.  Publications, Presentations, Theses:
    1.  Judeikis, H.S.  Heterogeneous Removal of 502 ^rom tne Atmosphere.
    Presented at:  8th Aerosol Technology Meeting, Chapel Hill, NC, October
    6-8, 1975.

                                     58

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2.   Judeikis, H.S. and T.B.  Stewart.   1976.   Laboratory Measurement of SCL
Deposition Velocities on Selected Building Materials and Soils.   Atmos.
Environ.   10:769.

3.   Judeikis, H.S.  Heterogeneous Interactions of Atmospheric SCL.
Presented at:  Workshop on the Chemistry of Atmospheric Sulfur,
Philadelphia, PA,   October 12-14, 1976.

Plans:

1.   To complete and publish  work on S02 in SOp-O^-Np-HpO mixtures.

2.  Begin studies on the addition of ammonia and/or hydrocarbon + NO  to
the reaction mixtures.                                             x
                                  59

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     Table I.  Reactivities and Projected Atmospheric Rates for
                    Heterogeneous Removal of SO-
                                                           SO_ Removal
                                                              %/hour
                                _ _ _
                                1.0 x 10"3                     32
                                        -4
  ;_v^o                          5. 5 x 10                      18
                                        -4
Mojave Fly Ash                 5. 0x10                      16
A12O3                          4. 0 x 10"4                     13
MnO2                           3.0 x 10"4                     10
Pb02                           7.0 x 10"5                      3
Charcoal                       3. 0 x 10"5                      1
NaCl                           3.0 x 10"6                      0. 1
MnCl,                        <1.0xlO"6                     <0.03
                   3                     6
River Bend Fly Ash           <1.0xlO                      <0.03
 <£  is the fraction of SO_-solid collisions that lead to SO_ removal.

 Projected atmospheric removal rates assuming an urban aerosol loading
 of 100 //g/m  having the same reactivity as the indicated solid.
3
 Measurements on this material as received indicated a high sulfate
 content and low reactivity.  Experiments on the same material after
 washing with distilled water to remove soluble sulfates gave a
 reactivity comparable to that measured for Mojave Fly Ash.
4
 20-30%  uncertainty

 The data is  for metal exposure to  SO,,.  With prolonged exposures,
 the reactivities gradually diminish and ultimately approach zero,
 indicating  S0»  removal occurs  by  capacity limited reactions.
                                    60

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           Table II.  Deposition Velocities for SO- Removal
         .                          -                   Deposition Velocity
Material                          	             	cm/sec	
           3                             -4
Cement -I                     3.2 x 10                      2. 5
                  3                     -4
Ready Mix Cement              2.6x10                      2.0
Exterior Stucco - I              2.3xlO"4                     1.8
Cement - H3                    2.0xlO"4                     1.6
Exterior Stucco - II3            1. 1 x 10"4                     0.86
Adobe Clay Soil                 8.4xlO"5                     0.66
Sandy Loam Soil                8.3x10"                      0.65
                                        -6
Asphalt                         5. 1 x 10                       0. 04
 Roman numerals indicate different sources for the materials used.
  is the  fraction of SO_-solid collisions that  lead to SO_ removal.
                       £                              Lt
3
 Cured.
                                    61

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1.  Task Title:  Structure and Reactivity of Adsorbed Oxides of Sulfur and
Other Small Sulfur-Containing Molecules.

2.  Objectives:

         To determine the structure and reactivity of adsoroed oxidos of sul-
fur and other small sulfur-containing molecules which nay exist on atmos-
pheric aerosols.

3.  Institution:  Texas A&M University, College Station,  Texas
    Investigator:  J.H. Lunsford

4.  EPA Project Officer:  J.L. Durham

5.  Progress:

         It has been observed that under rather mild conditions, sulfur dioxide
undergoes a variety of surface reactions.   One such reaction occurs between
S02 and magnesium oxide.  On the basis of spectroscopic data, it is evident
that sulfite ions are readily formed on the surface, and  that except at elevated
temperatures of more than 200°C, it is not possible to oxidize these to the
sulfate form with molecular oxygen.  A limited number of  these sulfite ions
may, however,  be photochemically oxidized to SO; ions on  the surface of mag-
nesium oxide in the presence of adsorbed water vapor and  oxygen or nitrous
oxide.

         The reaction between H?S and molecular oxygen or air was carried
out at 25°C over magnesium oxide, MnNaY and NaY zeolites, and amorphous
silica-alumina.  The surface products, as determined by X-ray photoelectron
spectroscopy (XPS) and electron paramagnetic resonance (EPR) spectroscopy,
were different on each of the surfaces.  On magnesium oxide sulfide ions2
elemental sulfur, and sulfite ions were observed,  as well as S,~ and S20~
ions.   Only elemental sulfur was formed on the zeolite samples, and no
reaction products were detected on the amorphous silica-alumina.  Clearly,
it is  difficult to form 504 from HUS at moderate temperatures using molecular
oxygen as an oxidizing agent.

         Although these experiments indicate the difficulty in oxidizing a
reduced form of sulfur to sulfate ions, it is possible to do so provided
the correct catalyst is used. The oxidation of S02 has been catalyzed, for
example, by manganese ions in aqueous solution.  SO- may  be oxidized to
sulfate ions by hydrated Mn2+ ions in MnNaY zeolites and  on amorphous
silica alumina.

         Nitrogen dioxide has been found to be a more effective oxidizing
agent than molecular oxygen.  At pressures of several torr, N02 is capable
of oxidizing S0? to S07  at 25°C on the surface of silica gel and amorphous
silica alumina.  Nearly monolayer coverages are obtained  after several hours
of reaction.  The XPS spectrum of the S(2p) and N(2p) lines for sulfur and
nitrogen on the surface of silica gel and in ammonium sulfate are depicted
in Figure 1.
                                    62

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5.  Progress (cont'd):

         Results show that the radical  anions So and S^O  were also formed as
    by-products of the  reaction on magnesium oxide.   It appears that elemental
    sulfur from the Claus reaction, probably in the  form of S~> reacts with
    lattice oxide ions  of MgO yielding S?0".  The same ion could also be
    formed by ultraviolet irradiation of adsorbed COS or CSp.

         The formation  of H9S~ was detected using EPR spectroscopy.  This ion
    may be produced by  the Tow temperature reactions of hLS with trapped elec-
    trons on the surface of MgO.  The EPR spectrum was previously attributed
    to the HpS" ion; however, using sulfur-33 labelled FLS, we demonstrated
    that the paramagnetic molecule contained two non-equivalent sulfur atoms.

6.  Publications, Presentations, and Thesis:

    1.  M.J. Lin and J.H. Lunsford.  1975.  Photooxidation of Sulfur Dioxide
    on the Surface of Magnesium Oxide.   J. Phys. Chem.  79:892-897.

    2.  M.J. Lin and J.H. Lunsford.  1976.  Electron Paramagnetic Resonance
    Evidence for the Formation of S90~ on Magnesium Oxide.  J. Phys. Chem.
    80:635-639.                    ^

    3.  M.J. Lin and J.H. Lunsford.  1976.  An EPR Study of H9S ~ on Magnesium
    Oxide.  J. Phys.  Chem.  80:2015-2018.                   ^ L

    4.  M.J. Lin.  Structure and Reactivity of Sulfur-Containing Molecules
    Adsorbed on Magnesium Oxide.  Ph.D. Dissertation, Texas A&M University, TX.

7.  Plans:

    1.  To investigate the formation of sulfate ions on surfaces, starting
    with reduced forms  of sulfur and oxidizing agents such as molecular
    oxygen, ozone and nitrogen dioxide.

    2.  To emphasize the quantitative aspects of these surface reactions.
                                        63

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 10.0 -
 7.5
 5.0-
•o
 x
to
Z
O
O
 2.5-
40.0
30.0
20.0
 10.0
                                        U.Or
      J	I	I	L
                                        13.0 -
                                        12.0-
                                        10.0
     174      170      166                   406     402     398
                          BINDING  ENERGY  (,v)
    Figure  1.  S(2p) and  N(ls) photoelectron lines  from (a) silica  gel
    exposed to S02 and N02  and (b) (NH4)2$04.
                                      64

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1•    Task Title:   Structure and Reactivity of Adsorbed Oxides  of Sulfur.

2.    Objective:

          To develop photoelectron and infrared spectroscopy as  a technique
     for studying oxides of sulfur on aerosols.

          To determine the mechanism for the oxidation of S02  to SO,  on
     surfaces.

          To identify ions such as S^O" which may be produced  during  the
     photochemical reaction of H?S wfth S02 on magnesium oxide.

3.    Institution:  Texas A & M University, College Station,  Texas
     Investigator:  J.H. Lunsford

4.    EPA Project Officer:  J.L. Durham

5.    Progress:

          The past year has been devoted to photoelectron studies of  sulfur
     species on pure oxides, collecting flyash samples from the  River Bend
     Power Plant, and collecting atmospheric aerosols which  were near the
     Labadie Power Plant in St. Louis.  In order to identify surface  species
     by photoelectron spectroscopy, the energy of the emitted  photoelectron
     must be converted into a binding energy for sulfur.  This is not a
     simple problem since most of the samples of interest are  insulators
     ana cnarring effects become serious.   By employing a standard of gold
     evaporated onto the samples, along with an electron flood gun, binding
     energies with an error less than ±0.5 eV have been obtained.  It has
     also been necessary to develop computer programs for smoothing and
     deconvolution of the data.

          A study of S02 and hLO adsorbed on MgO/Mg(OH)2 confirms our
     earlier conclusions, basea on infrared spectra, that surface sulfite
     ions are formed at 23°C.  The deconvoluted photoelectron  spectrum of
     this species is compared with the spectrum of elemental sulfur,  Sg,
     in Fig. la and Ib.  Heating the sample in 02 at elevated  temperatures
     (200°C) was required for the oxidation of surface sulfite ions to
     sulfate ions.

          The Riverbend flyash sample revealed that most of the  sulfur exists
     on the surface as sulfate ions (Fig.  2a).  A number of other elements
     were detected in a broader scan of the flyash.

          An unsmoothed spectrum from an aerosol sample collected in  St.
     Louis shows that two types of sulfur are present; one is  a  sulfate
     ion and the other resembles an inorganic sulfide ion or an  aromatic
     sulfide (Fig. 2b).  The samples also contained nitrogen in  the form
     of ammonium ions, which is consistent with the results  of other
     laboratories.

          Limited progress has been made in determining the  mechanism for
     the oxidation of S02 to SO^ on surfaces.  In stack gases, NO  may be


                                     65

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the oxidant rather than CL.   In an effort to investigate this possibility
SCL and NCL were sequentially adsorbed or coadsorbed on MgO, and the
surface spears were identified by infrared and ohotoelectron spectroscopy.
Preliminary results indicate that the adsorption of SO- first (yielding
surface sulfite ions), followed by gxposure to NCL resulted in the
partial oxidation to SO* ions at 25 C; however, coadsorption did not
yield a more oxidized fo>m of sulfur.  This may be explained by the fact
that NOp adsorbs as ions which are not capable of oxidizing SCL, whereas,
molecular NCL oxidizes the surface sulfite to sulfate ions.  As indicated
previously, molecular oxygen is not capable of oxidizing sulfite ions at
room temperature.
     SCL and H0 were found to react at
25°C
                                            on magnesium oxide, forming
a parama"gnetic'~species which has been identified at S^O".  Hyperfine
splitting due to sulfur-33 was used to confirm the identification.  The
previously studied S,~ ion is also formed.  Thus the Glaus reaction
yields elemental sulfur in the form of S?, S.,...Sfi, ...S  molecules.
The Sp molecules react with surface oxide ions, forming SLO".  This
requires a degassed MgO surface for its formation, but it is stable
presence of air.
                                                                    ion
                                                                    in the
Publications, Presentations, Theses:

1.  A paper is scheduled to appear in the Journal of Physical Chemistry.

2.  A review of the literature on adsorbed oxides of sulfur has been
completed and will be published.

Plans:

1. To develop photoelectron spectroscopy as a technique for studying
atmospheric aerosols and for following in the laboratory the oxidation
of SCL on surfaces.

2.  To focus on the mode of oxidation of SCL to SCL or SCH on surfaces
by investigating the reactions which occur Tn thin aqueous films on metal
oxide surfaces.  Silica and alumino silicates will be investigated using
both CL and NpO as oxidants.  On pure surfaces it is anticipated that
the oxidation reactions will be slow; however, introducing transition
metal ions should catalyze the reactions.  Work will continue on the sur-
face analysis of atmospheric aerosols.
                              66

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   169.0        168.0         167.0       166.0        165.0        164.0        163.0        162.0




                                   BINDING ENERGY IN EV




Figure 1. Photoelectron spectra of sulfur 2p: (A) elemental sulfur, Sg, (B) 863  ions on MgO.
                                               67

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                                              COUNTS/CHANNEL
o -n
3 '
o -u
K :r

|s
2 o
o o

3 D
-^
  CD
  O
  r+

  S

  O
   c_

   -*l
   c
   -1

   NJ

   T3
   Crt

   O
   o
   03

   3-
   CD


   CO

   O
   Q.

   o
   tc
   Q.
   en
S
            en
            in
            en
            to
—  169.0
                                                                      — 169.1
                                               161.6
                                                     68

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1.  Task Title:  Reactions of Sulfur Dioxide in Aerosols.

2.  Objective:

         To measure the extent of reaction of sulfur dioxide in aerosols,
    particularly as influenced by PH and various catalysts.

3.  Institution:  The University of Texas at Austin, Austin, Texas
    Investigator:  D.M. Himmelblau

4.  EPA Project Officer:   J.L. Durham

5.  Progress:

         Various models have been set up to represent the  mass transfer and
    reactions of sulfur dioxide with aerosol particles.   Reaction rate coeffi-
    cients have been calculated based on the available literature.  However,
    due to the varying set-ups of previous investigators,  it is difficult  to
    predict reaction rate coefficients for the experiments to be carried
    out in this investigation.  About four orders of magnitude difference  have
    been determined from one experiment to another from  the  articles in the
    literature.

         A reaction tube has been set up with adjustable residence times so
    that the reactions of sulfur dioxide with the aerosols can be measured
    under controlled conditions.  Particle size distributions have been
    measured for two aerosol generators and various supplementary parts of
    tne equipment have been assembled.

         Since the amount of sulfur that is accumulated  in the aerosol par-
    ticles is so small, radioactive sulfur-35 will be used to determine the
    overall transfer to the aerosol particles.

6.  Publications and Presentations, Theses:  None

7.  Plans:

    1.   To complete the assembly of all the experimental apparatus.

    2.   To test the individual components.

    3.   To calibrate the various pieces of equipment.

    4.   To establish that aerosols of known size can be  transmitted  through
        the reaction section and caught in the sampling  filter without
        substantial losses.

    5.   To estimate the reaction rate coefficients by using  radioactive sulfur
        dioxide.
                                       69

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1.  Task Title;   Mass Transport Models

2.  Objective:

    Develop a mathematical  model  of the  absorption  of  S0?  by  water  and  compare
    with experimental results.

3.  Institution:   Northrop  Services. Inc.,  RTF,  NC.
    Investigator:   John Overton

4.  EPA Project  Officer:  J.L,  Durham

5.  Progress:  In  order to  model  the absorption  of  a gas by a liquid, several
    factors must  be taken into  consideration:   (1)  diffusion  or  transport
    processes within the  aerosol, (2) transport  of  gas through the  gas-liquid
    interface, (3)  the chemistry of the  species  within the liquid.

         The absorption of  S0£  (at ppm concentrations) by  pure water is a
    very simple  system with respect to the  above factors.   This  is  because
    only a few products are formed in the water  by  the S02 and only one (rever-
    sable) kinetic  equation is  necessary to describe the significant chemical
    reactions.  Further,  this reaction is sufficiently fast in both directions
    to be considered instantaneous; i.e. equilibrum maintained point wise  within
    the liquid.   The reaction is:
             S02£    2    H30+ + HS03-

    where S02P   is the liquid phase SOp  (^503).
         Because of the chemical  equilibrium, and the  fact  that
    «[HS03~] (for tne particular experimental  conditions considered  the  con-
    centration, [HS03~], wnicl1 makes up over 99% of the dissolved  $03, approximately
    satisfies the molecular diffusion equation  without chemical  reaction  terms.
    i.e.,
           a[HS03-]

    D = diffusion coefficient.

         The effect of the chemistry is taken into account by the gas-liquid
    interface boundary condition.   This condition is that the current, J, at
    the interface is,
            = _ D 3[HS03-]   =    k {[S02g] - H[S02£]
                     3X

    where

          k = a mass transfer coefficient,
          H = Henry's law constant
     [S02^]i = interface value of [502^1

     [S02g]  = gas phase value of S02-
                                       70

-------
                                                         -          p
    assuming charge neutrality one finds  that [S02«-]  =  K'1   [HS03~] :
    K = chemical equilibrium constant.  Thus, at  the  interface,
         The experimental  data simulated  is  for  a  bulk  water  system  and was
    taken from P.P.  Terraglio and R.M.  Manganelli, The  Absorption  of Atmospheric
    Sulfur Dioxide by Water Solution's, JAPCA,  17(6), June  1967..

         In the experiment, 20 Petri  dishes,  each  with  water  to the  same  level,
    were placed in a chamber.  S02 was  introduced  into  the  chamber and kept  at
    a constant level.  Approximately  every six minutes  a  dish was  removed  and
    analysed for the quantity of dissolved SC^,  Thus a set of data, dissolved
    S02 versus time, was  obtained.  For purposes of the model, the essence of
    the experimental setup is illustrated in  Figure 1.

         Numerical simulations of the model  are  compared  to the experimental
    data in Figure 2.  The diffusion  coefficient (D)  and  transfer  coefficient
    (k) were varied  to produce the best fit.  The  values  used for  the  plots
    in Figure 2 are  D = 1.5 x 10~4cm2/sec and k  =  ,75 cm/sec, (D is  too high
    by a factor of 10, which indicates  mixing in the liquid by means other
    than molecular diffusion).

         Assuming the water thickness = 1  urn, D  =  10~5  cm2/sec, and  R  = 1,
    an insight into  the relative importance  of  the factors  that would  be
    important in aerosols was obtained.  Figure  3  is a  plot of the fractional
    saturation concentration of HSOs" in  the  interface  and  in the  liquid  as
    a function of time.  As can be seen,  for  times greater  than 10~2 second.
    the surface and  average values are  essentially the  same.   This behavior
    indicates a nearly spatially uniform  distribution of HS03~.  Tn-is  condition
    is equivalent to an infinite diffusion coefficient.  Thus the  major
    factors to be considered are the  chemistry  and the  resistance  to transport
    through the air-liquid interface.

6.  Publications, Presentations and Theses:   None

7.  Plans:

         The physics and chemistry of liquid  aerosols are,in  general,  much
    more complex than indicated by the  model  presented  here.   Thus,  models
    and programs that can handle more complicated  cases are being  developed.
                                        71

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AIR
WATER
                                            J = -K([S02 ] - H  '  [S02£])
                                                               SURFACE OF WATER
                                                    3C
                                                    — = 0  (current = 0)
                                                         •^-BOTTOM OF CONTAINER
                                Figure  1  .
                                   72

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               GAS PHASE SO2 = 0.81 ug/m"
    GAS PHASE S02 -- 2.54 ug/-,V3
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           GAS PHASE SO2 = 5.54 yg/m
          HOURS



GAS PHASE S02 = 8.73 -
     .0
                 .5         1.0

                   HOURS
          HOURS
                                                                            1.5
                                               i  i  i  i   i i  i—rn—rr~l
  Figure   2.    SIMULATION OF THE  ABSORPTION OF S02 BY WATER (EXPERIMENT: +;


                SIMULATION: - )
                                      73

-------
                                    LOG (time)
     1.0-
IX
  *
 X
                                         GAS-LIQUID
                                         INTERFACE VALUE
                                         AVERAGE VALUE
                                    O   AVERAGE
                                         WITH D = co
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                                                                         -6
                                                                         -7
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                              .3     .4      .5      .6
                                    TIME (sec)
            Figure  3.  FRACTION OF SURFACE AND AVERAGE CONCENTRATIONS OF
                      DISSOLVED S02  (:  HSO^) IN H20 OF DEPTH  =  1 y
                                       74

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               A.  ATMOSPHERIC PROCESSES AND EFFECTS
     5.    Technique Development.  Development of new instruments or
techniques required for the aerosol research program.
   Funded by USEPA, ORD, OALWU.  Program Element 1AA603 and 1AD712,
                                  75

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1-  Task Title:  Formation of Atmospheric Aerosols  -  Nonideal  Characteristics
    of Impactors.

2.  Objective:

         To study the nonideal  characteristics  of single-stage and  cascade impactors
    that are important for their correct application  in  aerosol  sampling.   Both
    laboratory and commercial  impactors have been studied.

3.  Institution:  University of Minnesota, Minneapolis,  Minnesota
    Investigator:  K.T.  Whitby

4.  EPA Project Officer:  W.E.  Wilson

5.  Progress:

         In a thesis study by A.K.  Rao, the performance  of  the impactor stages
    was found to be significantly affected by the nature of the  aerosol  and the
    collection surface.   With dry,  solid surfaces or  dry, solid  aerosols,  bounce
    and blowoff was severe.  Liquid aerosols or liquid-coated  collector surfaces
    were close to the Marple theory in behavior.   Glass  fiber  filter media surfaces
    reduced bounce, but significantly changed the impactor  characteristics.  Whatman
    filter paper collection surfaces did not reduce particle bounce appreciably.

         Experimental studies of slotted impactors  by Willeke  show  that they per-
    form with a sharpness of cut close to the theoretically predicted  value,if
    used unaer the conditions of the numerical  mode.   Sideways flow entrance
    and impaction onto a fibrous surface may change the  collection  efficiency
    considerably (Figure 1).

6.  Publications, Presentations, Theses:

    1.  Rao, A.K.  An Experimental  Study of Inertia!  Impactors.   Ph.D.
    Thesis.  Mechanical  Engineering Department, University  of  Minnesota, MN,
    June  1975.

    2.  Rao, A.K. and K.T. Whitby.   Nonideal Collection  Characteristics of
    Single-Stage and Cascade Impactors.  Accepted by  Am, Ind.  Hyg.  Assoc.  J.
    1976.

    3.  Willeke, K. and J.J. McFeters.  1975.  The Influence of Flow Entry and
    Collecting Surfaces on the Impaction Efficiency of Inertial  Impactors,
    J. Colloid Interface Sci.  53:121-127.

    4.  Marple, V.A. and K. Willeke.  Inertial  Impactors:  Theory,  Design and
    Use.   In:  Fine Particles:  Aerosol Generation, Measurement, Sampling, and
    Analysis  (6.Y.H. Liu, ed.), pp. 411-446, Academic Press, New York,  1976.

    5.  Will eke, K. 1975.  Performance of the Slotted Impactor.   Am. Ind.
    Hyg. Assoc. J.  36:683-691.
                                       76

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7.   Plans:
         Work on the nom'deal  behavior of impactors  and  cyclone  samplers  will
    continue in the Particle Technology Laboratory under the direction  of
    Dr.  B.Y.ri.  Liu.
                                      77

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                       100

                       90-

                       80-

                       70-

                       60

                       50

                       40

                       30
                       20
                         /
                        10-
  i   i    i   i    i   r
	ARB POLYETHYLENE STICKY FILM
	DOWCORNING OIL-COATED
    GLASS PLATE
	GLASS FIBER FILTER
    (GELMAN TYPE A)
	 GLASS PLATE
 O IIOpmPSL
 O 0794pm PSL
 A 0 790pm PSL
   
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1.  Task Title:  Sources and Trace Metals  in  Urban  Aerosols

2.  Sub-Task Title:   Development and Application  of Analytical  and  Sampling
                     Techniques

3.  Objectives:

         To develop  a sensitive elemental  analysis  and  sampling technique
    capable of handling very small  samples.

4.  Institution:  Department of Oceanography, Florida  State  University
                  Tallahassee, Florida"  32306
    Investigator:  John W.  Winchester

5.  EPA Project Officer:  Ronald K. Patterson

6.  Progress:

        The Jensen-Nelson sampler (Streaker") was developed  and has
    been applied successfully to various aerosol  studies.  The  samples
    consist of strips of 0.4um pore size Nuclepore  filter  firmly
    attached to frames.  The sampler is  simply a  siiding-sucking ori-
    fice moved by a  clock motor at the rate  of 1  mm/hr along the length
    of the filter so as to draw about 1  liter/min of air through a
    continuously-moving 2 mm x 5 mm rectangular area of the  filter.
    The device is positioned in the field so  that the  air  is drawn
    upward from the  under-side of the filter  thereby excluding  particles
    30 urn and larger.

        In the analysis laboratory, the  sample is moved automatically
    for successive bombardments by a stepping motor drive  with  electric
    control.  The analysis techniques used on these samples  are Proton-
    Induced X-Ray Emission (PIXE) and Proton  Elastic Scattering Analysis
    (PESA) which yield elemental composition  using  the proton beam  of a
    Van de Graaff accelerator.  Under routine PIXE  analysis  conditions,
    85 bombardments, corresponding to a  week  of sampling time are currently
    performed in four hours of accelerator time.   Other combinations of
    filter pore size, orifice area, and  orifice speed  can  be introduced.
    For urban atmospheres, however, the  loading obtained with the above-
    mentioned design is optimum:  giving routine  detecting limits in the
    order of 10 - 100 ng/nP for sulfur and heavier  elements  by  PIXE; and
    sensitivity sufficient to measure lighter elements by  PESA.

        For both PIXE and PESA analyses, the  proton beam is  collimated
    to a rectangular area of 2 mm x 5 mm and  inside the streak.  The X-
    rays or the scattered protons are detected at backward angle and
    give rise to a pulse-height spectrum resolvable into the individual
    elements in the  sample.  With this arrangement, the time resolution
    is 2 hours.

        New collection surfaces for the  Battelle-type  cascade impactor
    were designed so that size fractionated  aerosol samples  could be
    analyzed by PIXE and PESA techniques.   For special  sampling needs
    two larger stages were designed for  the  Battelle sampler which  allows
    the collection of 16.0, 8.0, 4.0, 2.0, 1.0, 0.5, 0.25, and  <0,25ym
    particles.


                                    79

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        Proton-induced X-ray emission  analysis  has  been  shown to  be  a
    fast, inexpensive, reliable,  and convenient method for  routine multi-
    elemental  trace analysis.   The  major component  procedures of  such  an
    analysis are sample preparation, bombardment, and analysis of pulse-
    height spectra.  To meet the  dual  goals  of  a rapid and  an unambiguous
    analytical  technique, each  of the  component procedures  must be opti-
    mized.  As  part of this grant sub-task title, a status  report was
    written on  the optimization of  PIXE  pulse-height  spectra analysis.
    This analysis was based on  a  model of the radiation  environment  in
    which an energy dispersive  detector  is placed in  PIXE analysis;  and
    on the intrinsic characteristics of  the  detector.  The  present model
    has been coded in the Fortran program, REX. The  parameters of the
    model are sought using a least  squares minimization.

7.  Publications:

    1.  J.W. Nelson, B, Jensen, G.G. Desaedeleer, K.R. Akselsson, and
    J.W. Winchester.  1976.  Automatic Time  Sequence  Filter Sampling
    of Aerosols for Rapid Multi-element  Analysis by Proton  Induced
    X-Ray Emission.  Advances  in  X-Ray Analysis.  19:415-425.

    2.  H.C. Kaufmann, K.R. Akselsson, and W,J, Courtney.   1976,  REX:
    A Computer  Program for PIXE Spectrum Resolution of Aerosols,
    Advances in X-Ray Analysis.  19:355-366.

    3.  B. Jensen and J,W. Nelson.  Novel Air Sampling Apparatus  for
    Elemental Analysis.  In:  Proc. 2nd  Intl , Conf.  Nucl , Methods in
    Environ. Res., Columbia, MO,  July  1974,  Report Issued  October,  1975.

    4.  T.B. Johansson, R.E. Van  Grieken, J.W,  Nelson, and  J,W. Winchester.
    1975.  Elemental Trace Analysis of Small Samples  of  Proton-Induced
    X-Ray Emission.  Anal, Chem.  47:855-860.

    5.  J.W. Nelson and D.L. Meinert.  1975,  Proton  Elastic Scattering
    Analysis-A  Complement to Proton-Induced  X-Ray Emission  Analysis  of
    Aerosols.   Advances in X-Ray  Analysis.   18:598-605.

    6.  J.W. Nelson, J.W. Winchester and R.  Akselsson,   Aerosol Composition
    Studies Using Accelerator Proton Bombardmen.  In:  Proc. 3rd  Conf.
    on Appl. Small Accelerators,  Vol.  1, CONF-741040-P1 , USERDA,  Denton,
    Texas, October 1974.

    7.  R. Akselsson, J.W. Nelson,  and J.W.  Winchester.   1975.  Proton
    Scattering  for Analysis of Atmospheric Particulate Matter.  Bull.  Am.
    Phys. Soc., 20:155 and Conf.  Proc.  (In Press).

    8.  H.C. Kaufmann and R. Akselsson.   1975.   Non-Linear  Least  Squares
    Analysis of Proton-Induced X-Ray Emission  Data. Advances in X-Ray
    Analysis.  18:353-361.
                                    80

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    9.   R.E.  Van Grieken, T,B.  Johansson,  K.R.  Akelsson,  J.W,  Winchester,
    J.W.  Nelson, and K.R. Chapman,   1976.   Geophysical  applicability  of
    Aerosol  Size Distribution Measurements Using  Cascade  Impactors  and
    Proton Induced X-Ray Emission,   Atmospheric Environment.   10:571-576.

   10.   T.B.  Johansson, R.E.  Van Grieken,  J.W,  Nelson,  and  J.W.  Winchester.
    1975.  Element Trace Analysis of Small  Samples  by Proton-Induced  X-Ray
    Emission,  Analytical Chemistry, 97:855.

   11.   T.B.  Johansson, R.E.  Van Grieken and  J.W,  Winchester,   Interpretation
    of Aerosol  Trace Metal  Particle Size Distribution.   In:   Proc.  2nd InH.
    Conf. Nucl.  Methods in Environ. Res.,  Columbia, MO, July,  1974.   Report
    Issued October, 1975.
8.  Plans:
         This grant is complete.   A final  report  is  forthcoming.
                                   81

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1.  Task Title:  Formation of Atmospheric Aerosols - Development of a Sulfur
    Aerosol  Analyzer.

2.  Objective:

         To  develop an instrument to continuously measure aerosol  sulfur at
    ambient  atmospheric concentrations using a commerical flame photometric
    elector and  a newly developed pulsed electrostatic precipitator.

3.  Institution:  University of Minnesota, Minneapolis,  Minnesota
    Investigator:  K.T. Whitby

4.  EPA Project Officer:  W.E. Wilson

5.  Progress:

         An  instrument which combines a pulsed electrostatic precipitator
    and a flame photometric detector to measure ambient  sulfur aerosols has
    been developed.  A laboratory version of the instrument is currently
    operating and will be used to measure sulfur aerosol concentrations in
    the Los Angeles freeway study.  The present instrument configuration
    will detect sulfur aerosols down to T-Z yg/m^ as sulfur.  A heater
    located upstream of the instrument will be used to discriminate between
    sulfuric acid and other sulfur aerosols.

6.  Publications, Presentations, Theses:

    1.  Kittelson, D.B., R.I. McKenzte, B.Y.H. Liu, D.Y.H. Pui and F.D. Dorman.
    Natrottal Bureau of Standards/University of Minnesota Stflfur Particle Analyzer
    Project,  EPA-IA6-P5-0684, PfBS/EPA Energy/Environment Project, semi-annual
    report from NBS to EPA Off fee or Energy, Minerals.,, and Industry.  Washington,
    D.C.,  Z0460
                                       82

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1.  Task Title:  Simultaneous Comparison of the Electrical  Aerosol  Analyzer
    and the Diffusion Battery for Atmospheric Aerosol.

2,  Objec'cives:  To make simultaneous performance evaluations of the
    Electrical Aerosol Analyzer (EAA) and the diffusion battery (DB) while
    sampling atmospheric aerosol.

3.  Institution:  University of Paris
    Investigator:  J. Bricard

4.  bPA Project Officer:  T. Ellestad

5.  Progress:

         In preparation for making size distribution measurements with
    diffusion  battery and condensation nuclei counter (CNC),  the CNC's response
    as a function of particle size was studied with sodium chloride nuclei
    produced by a Liu generator.  Contrary to the existing literature, the
    CuC response showed a marked dependence on particle size  below 0.06 ym
    diameter.   The phenomenon was observed both for expansion-release counters
    using water as the condensing fluid and for continuous-flow counters
    employing  Duty! alcohol.  This finding has important implications
    beyond size distribution reduction from diffusion batteries:  previous
    estimates  of coagulation coefficients, nucleation rates,  and other ultra-
    fine aerosol behavior may need revision.

6.  Publications, Presentations, and Thesis:  None

7,  Plans:

    1.  Compare performances of the EAA and the diffusion battery on
        laboratory-generated aerosol.

    2.  Compare size distributions of atmospheric aerosol as  measured by
        the EAA and the diffusion battery.
                                     83

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1.   Task Title:  Determination of Sulfate Ion  Concentrations  in  Human  and
                  Animal  Serum using High Pressure  Liquid Chromatography

2.   Objective:

          To develop a simple means of measuring  human  and animal  serum
     sulfate concentrations in subjects which  have  been exposed to aerosol
     sulfate and sulfite  pollution.

          To determine if increased exposure to aerosol sulfates  necessarily
     results in  an increased sulfate concentration  in blood serum or if
     other reactions occur.

          These  projects  are being done in cooperation  with Dr. E. Sawicki.

3-   Institution:   Environmental  Protection Agency, ESRL, ARB
     Investigator:  L.L.  Spiller and R.F. Reardon (student aid)

4.   EPA Project Officer:  W.E. Wilson

5.   Progress:

          The serum sample is dialyzed using Fisher dialysis tubing (cat.
     no. 8-667D).   This is done to prevent the  large proteins  in  the serum
     from damaging the column of the chromatograph.  Other methods for
     removing these proteins have changed the  results of the analysis.

          The sample is analyzed for sulfate on the high pressure liquid
     chromatograph (hPLC).

          A blank  made from the deionized water used in dialysis  is run on
     the HPLC.

          A first attempt at analyzing human and  rabbit serums have yielded
     results which were well within the range  of  expected values  and were
     very promising.

6.   Publication,  Presentation, Theses:  None

7.   Plans:

          Current plans include analysis of samples which have been "spiked"
     with very high levels of Na^SC^ ^$03 and  NaNO£  in order to determine
     the efficiency of the procedure and to see if  the  serum proteins react
     in any way with the added ions.
                                  84

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1-  Task Title:  Comparison study of data collected  with the  dichotomous
                 and high-volume samplers.

2-  Objective:  To meet the requirements for a masters thesis and  to
                establish a data base from which the Aerosol  Research  Branch
                can make recommendations to other agencies  and interested
                individuals regarding the use of these samplers.

3.  Institution:  University of North Carolina, School of Public Health,
                  Chapel Hill
    Investigator:  Tim McCarthy (student aid).

4.  EPA Project Officer:  W.E. Wilson

5.  Progress:  Samples were collected from January through  March,  1977,  on  the
    roof of the EPA Monitoring station (Cameo Bldg.) in downtown Durham.  The
    dichotomous samples have been analyzed and the analysis of the hivol
    samples are in progress.

6.  Publications, Presentations, and Theses:  None

7.  Plans:  To complete comparison study by July, 1977.
                                     85

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1.   Task Title:  A Cyrogenic Procedure for Concentrating Rating  Trace
                  Gases in the Atmosphere

2.   Objective:

          To determine the distribution, atmospheric loading,  sources and
     sinks of halogenated compounds;  the effect of fluorocarbons  on the
     depletion of ozone.

3.   Institution:  EPA-ERC, ESRL-ARB
     Investigator:  L.L. Spiller,  M.  Miller

4.   EPA Project Officer:  W.E. Wilson

5.   Progress:

          Detection of small  concentrations of gaseous air pollutants has
     been achieved by the use of the  fourier transformer spectrometer,
     nitrogen-colled photo-detectors  and infrared paths of 400 meters or
     more.  For measurement of many of the trace gases on the  ambient air,
     a detection sensitivity of 10~10 atmos. or better required.   To
     achieve such low detection, the  pollutants have to be concentrated by
     separating them from the nitrogen, oxygen and water vapor.   Cyrogenic
     condensation followed by distillation thus appeared to be the most
     feasible technique for concentrating pollutants.   Results were obtained
     on 14 days between January and July 1975.

          Fluorocarbon -11 values  ranged from about 1.3 x 10"    atmos. at
     RTP, NC to 8 x 10-10 atmos. at New York City.

6.   Publications, Presentations,  Theses:

          Infrared Measurement of Fluorocarbons, Carbon Tetrachloride,
     Carbonyl Sulfide, and Other Atmospheric Trace Gases, APCA Journal, 25,
     No. 12, December 1975, pages  1220-1226.

7.   Plans:

          To develop defining techniques for fluorocarbon F-ll,  F-12, and
     F-114 determination.
                                 86

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1.    Task Title:   Collection of Atmospheric NO,, by Treated Filters

2.    Objective:

          Develop a simple and inexpensive method of measuring ambient
     N0? levels  in the atmosphere.

3.    Institution:  EPA-ERC, ESRL-ARB
     Investigator:  L.L. Spiller and G.L.  Kay (student aid)

4.    EPA Project Officer:  W.E. Wilson

5.    Progress:

          The lab setup has made use of an N02 permeation tube, a tempera-
     ture bath,  and a bendix N02 analyzer to similate ambient NO^ concentrations
     and measure filter efficiency.

          Treat  a specific type filter with a f^-absorbing solution.   Allow
     the solution to dry onto the filter.

          Place  the treated filter in a filter holder and use a critical
     orifice followed by a vacuum pump to draw a specific flow rate of air
     through the treated filter.

          After  exposing the filter, analyze the concentration of N02  on
     the filter  using a quick and accurate method such as ion chromatography.

          To date, using only the Bendix analyzer, an efficiency of 94-93%
     in N02 pickup has been observed using a Fisher 9-802 cellulose filter,
     a triethanolamine-Sodium methoxide-5% Guaiacol solution, a humidity
     range of 20-60%, and a flow rate of 350-380 cc/minute.  These results
     have not been confirmed using the ion chromatograph analysis.

6.    Publications, Presentations, Theses:   None

7.    Plans:

          Current plans involve confirming the efficiency by use of ion
     chromatography, increasing the efficiency of the filter system to 100%.

          To increase the flow rate.

          To maintain high efficiency, and reduce the amount of guaiacol  in
     the treatment solution (the guaiacol  interferes with ion chromatography
     analysis).
                                 87

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1.  Task Title:  Instrumentation for Monitoring Meteorological  Data

2.  Objective:

         To develop a portable electronic systems  to  monitor wind  speed,
    wind direction, and temperature.

         To develop systems to control  pollutant samplers  as a  function
    of meteorological parameters.

3.  Institution:   EPA-ERC, ESRL-ARB
    Investigators:   L.L,  Spiller  and G.  DeJong (student aid)

4.  EPA Project Officer:   W.E. Wilson

5.  Program:

         A digitally programmed instrument to monitor wind speed/direction
    and to selectively control up to 4 different environmental  samplers
    was built and is being used in field  projects.  Circuitry to interface
    a digital tape  recorder (used by the  power industry to monitor power
    demand) to existing meteorological  instruments  is being developed.
    The recorder can store over 30 days of continuous time related data
    on 3 channels,  which  can be easily transferred  to a computer.   This
    will save much  time and error involved in manually transferring data
    from strip charts to computer punch cards.

6.  Publications, Presentations, Theses:   None

7.  Plans:

         Portable AC power generators, along with  an  AC line regulator  will
    be installed in the EPA mobile laboratory.  These generators will  enable
    tne van to be used for monitoring atmospheric  sulfur at locations  of
    high biogenic activity which are remote from human disturbances.  Low
    sulfur fuels will be used in the generators.  A Meloy  Model SA-285
    Sulfur Gas Analyzer,  which is capable of monitoring at 1 to 2  ppb
    levels, will  be used.
                                      88

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1.  Task Title:  Improvement of "Streaker"  Technique  for Automated  Collection
    and Analysis of Aerosols.

2.  Objective:

        To develop a new, More effective "streaker"  technique including
    separation  of aerosols into coarse and  fine fractions.

        To intercompare streaker collections - PIXE  analysis  with  other
    analytical  techniques.

3.  Institution:  Florida State University, Tallahasse, Florida
    Investigators:  W.  Nelson, J. Winchester, J.  Oenson

4.  i:PA Project Officer:  W.E. Wilson

5.  Progress:

        A circular, 2-stage streaker which  uses an impaction  stage  followed
    by a filter to give separate collection of fine  and coarse particles has
    been constructed and is being tested.  The series Nucleopore technique
    to obtain 2-stage particle size resolution is also being  tested.   Streaker
    results from the G,M. Sulfate Study have been compared with  those of the
    EPA dichotomous sampler.  Satisfactory  agreement (5% or better) was
    found for measurement of automobile-generated sulfate.

6.  Plans:

        Tests will be made to determine the adequacy of using the Nucleopore
    filter as a critical orifice to provide flow control.

        FSU will participate in an EPA sponsored intercomparison of aerosol
    measurement methods in West Virginia during Spring-1977.

7.  Publications, Presentations, and Thesis:  None
                                    89

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                 B.  AUTO-EXHAUST CATALYST PROGRAM
     Determination of chemical and physical properties of sulfuric acid
aerosol produced by automobile catalysts.
         Funded by USEPA, ORD, OHEE.  Program Element 1AA601.
                                   90

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"I-   Task Title:   Roadway Aerosol  Studies  During General  Motors  Sulfate
                 Dispersion Study

2.   Objective:

         To determine the mass flow rate  of particulate  sulfur  during
the GM Sulfate  study and derive the percent of fuel  sulfur converted to
aerosol sulfur.

3>   Institution:   Washington University,  St.  Louis,  Missouri
    Investigators:  E.S. Macias,  R.A.  Fletcher, J.D.  Husar and  R.B.  Husar

4.   EPA Project Officer:  L.L. Spiller

5.   Progress:

         The fine particulate sulfur concentration was determined 15 m
from the road,  at five different heights.  The win velocity profile  was
measured at three heights.  Samples were  collected at 30 min.  intervals
using TWO MASS  samplers.  Particulate sulfur was determined by  the flash
vaporization-flame photometric detection  method.  Samples taken before
and after the test track runs were used to correct for background sulfate
and determine the automobile contribution.

       The flow rate per unit length of the roadway (Q/L) was  calculated
from the fine particulate sulfur concentration as a function of: height
C  (z); and the component of the velocity profile perpendicular to the
roadway U(z), according to the following integral:
               Q/L  =    \    Cs(z)U(z) dz
       The average emission rate per car/unit length of roadway can be
calculated by dividing flow rate by traffic density.  The particulate
sulfur flow rate from the roadway averaged over the entire experiment
was 6.0 ± 1.2 yg/m/sec.  For the traffic density of this experiment,
1.52 cars/sec, the particulate sulfur-emission rate per car was 4.0 ±
0.8 g/m (6.4 ± 1.6 mg/mile).  This emission rate corresponds to a
13 ± 3% conversion of the fuel sulfur emitted as particulate sulfur
using the known fuel-sulfur content and estimated fuel consumption rate.

Publications and Presentati ons:

1.  Macias, E.S., R.A. Fletcher, J.D. Husar and R.B. Husar.  1976.
Dispersion and Mass Flow Rate of Particulate Sulfur from Catalyst-Equipped
Cars.  In:  The GM/EPA Sulfate Dispersion Experiment:  Selected EPA
Research Papers.  EPA-600/3-76-035,  p.81.

2.  Wilson, W.E. , L.L. Spiller, T.G. Ellestad, P.O. LaMother, J.G. Dzubay,
R.K. Stevens, E.S. Macias, R.A. Fletcher, J.D. Husar, R.B. Husar,
K.T. Whitby,,D.B. Kittelson, and B.K. Cantrell.  GM Sulfate Dispersion
Experiment:  Summary of EPA Measurements.  J. of Air Poll. Control Assoc.
In Press.

                             91

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    3.   Macias,  E.S.,  R.A.  Fletcher,  J.D.  Husar  and R.B. Husar.  Dispersion
    and Mass Flow Rate of Participate Sulfur  from Catalyst-Equipped Cars.
    Presented at:  Symposium on  the GM/EPA Sulfate Dispersion Experiment,
    Research Triangle  Park,  NC   April  12,  1976.

    4.   Macias,  E.S.,  R.A.  Fletcher,  J.D.  Husar  and R.B. Husar.  Particulate
    Sulfur Emission Rate  from a  Simulated  Freeway.  Presented at:  American
    Chemical Society Meeting, San  Francisco,  CA,  August 31, 1976.
7.   Plans:
         This  task is  complete.
                                 92

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-------
1.   Task Title:  Formation of Atmospheric Aerosols - Aerosol  Size Distri-
     butions and Concentrations Measured During the General  Motors Sulfate
     Study.

2.   Objective:

          To collect data on catalyst-equipped cars during October, 1975.

3.   Institution:  University of Minnesota, Minneapolis, Minnesota
     Investigator:  K.T.  Whitby

4.   EPA Project Officer:  L.L. Spiller

5.   Progress:

          GM and the EPA conducted a freeway simulation study  at the GM
     Hi!ford Proving Ground using only catalytic converter-equipped cars.
     During the study nearly 900 aerosol size distribution measurements
     were made,  both on and off the test track.  At the same time, sulfate
     and other measurements were also being taken.

          For measurements on the track, a 1975 four-door sedan was equipped
     with an optical particle counter, electrical analyzer,  condensation
     nuclei counter, and filter sulfate samplers.  Samples were collected
     over an 18-sec. period into an automated grab bag, where  the sample
     was held for the two minutes required for the measurement cycle of the
     in situ analyzers.  Measurements were also collected with a similar
     in situ measuring system, as well as with a dichotomous sampler from
     an EPA mobile laboratory located about 30 m from the roadway.

          The log-normal  fitting procedure was used to characterize all of
     the size distributions.  The amount contributed by the  cars during the
     test period was obtained by subtracting the averages of the background
     aerosol size distributions before and after the test period from the
     average during the test period (Table I).

          The average volumes added to the nuclei and accumulation modes for
     the car and EPA van were determined, and in both cases, about 70% of
     the aerosol volume is added to the nuclei mode (Table II).

          Background aerosol volume size distributions measured during the
     test show three distinct modes with mean sizes of approximately 0.03,
     0.24, and 6.0 ym (Figure 1).  Aerosol distributions measured during
     the run, both on and off the track, also exhibit three modes.  Those
     at 0.24 and 6.0 remain essentially unchanged while the smaller mode con-
     tains more volume than the background aerosol, and now has a mean size
     of about 0.02 ym (Figure 2).  The exact amount of the increase in
     volume of the smallest mode was greatly dependent on meteorological
     parameters.  The volume increase varied from about 20 ym3/cm3, when
     the wind direction was parallel to the track', to 2 ym3/cm3, when the
     wind blew across the track (Figure 3).  On days when the wind was
     parallel to the track, approximately 1/3 to 1/2 of the increase in
     volume during the test runs over background appeared in the 0.24 ym mode.
     No significant increase for the 0.24 ym mode was noted when the wind
     blew across the track.

                                  94

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 Conclusions:

 1.    Difference distributions  calculated by taking the
 the  average size distributions during the test and the
 ground distributions before and after the test suggest
 aerosol  volume (and hence mass) is  emitted in the size
 0.1  _m.
                                                        difference  between
                                                        average  of  the  back-
                                                        that most of the
                                                        range smaller than
      The geometric mean diameter by volume of this nuclei  mode aerosol  is
 about 0.02 ym.   Figure 1  compares the size distribution of aerosol  measured
 during the test period of GM Run 15 with the background.   It is clear
 that the size distribution of the accumulation mode (center mode)  and coarse
 particle mode (right-hand mode)  have not changed significantly.  It is  also
 clear that the nuclei  mode (left-hand mode) is contributed almost  entirely
 by the cars on the roadway.

      When the wind blows  across  the roadway (short aging  time), most of the
 aerosol  contributed by the cars  is smaller than 0.1  ym.  When the  wind  blows
 along the roadway (long aging time), coagulation transfers 1/3 to  1/2 of the
                                     urn size range (Figure 3).  Therefore,
                                     0.01 to 0.1 pm size range to the 0.1 to
                                     after emission and dilution at the  tail
 aerosol  to the  mode  in  the  0.1  to 1
 most  of  the aerosol  growth  from the
 1  um  range occurs  in the  atmosphere
 pipe.
2.    The highest contributions observed on the track were during GM Run 12
on  October 23 when the average wind direction during the run was 181°, or
the wind was blowing almost directly down the track (Table 1).  The total
fine particle volume (VFP) contribution for GM Run 12 is 3.35 ym3/cm3 at
the trailer and 37.1 ym3/cm3 as measured
           for comparison.  During Run 7
7 is shown
at 197°.
by the car on the
the wind was from
inside lane.   Run
the southwest,
3.   The arithmetic average over the 12 GM runs for which data can be
averaged for the trailer gives means of 1.49 and 0.63 ym3/cm3 for AVAN and
AVAC respectively, or a total fine particle contribution of 2.12.  A
somewhat comparable average for AVAN for the car is 7.00 ym3/cm3.

4.   When the wind was blowing almost directly across the track, values of
VAN measured in the car were significantly higher on the downwind side.
For example, for GM Run 4, wind W-SW, the average values on the downwind
leg near the track were VAN - 10.1, compared to an upwind value of 4.32
ym3/cm3.

5.   The geometric mean diameter by volume for the aerosol as emitted by the
cars is about 0.02 ym.  When the wind was directly parallel to the roadway,
as it was for GM Run 12, coagulation increased the mean size to about 0.04,
and significant mass was transferred to the accumulation mode.

6.   Correlation of particle sulfur measurements with fine particle volume
show that, within the accuracy of the measurements, the particle sulfur
can be accounted for by assuming that the aerosol is sulfuric acid in
equilibrium with water vapor.
                                   95

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Publications, Presentations, Theses:

1.  Whitby, K.T., D.B. Kittelson, B.K.  Cantrell,  N.J.  Barsic and D.F.
Dolan.   Aerosol Size Distributions and  Concentrations  Measured During
the General Motors Proving Grounds Sulfate Study.   EPA-600/3-76-035.
April  1976.

2.  Ibid., Submitted to:   Environ. Sci.  Tech.   November  1976.

Plans:
1.  To conduct a roadway study in Los Angeles during October
in order to measure aerosols, gases and particle chemistry.
1976
                             96

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                            Table I



            Typical and High Average Aerosol Volumes

               Measured by the Car and EPA Trailer
Measurement
Background
Test
Difference
a
VAN
.07
.05
.10
= 15

b
VAC
10.
8.
17.
12.
2
43
2
2


VAN
1
4
2
22
.96
.56
.35
.9


VAC
10
9
18
26
.4
.79
.3
.6


AVAN
1.
4.
2.
22.
88
51
25
7


AVAC
0
1
1
14
.2
.36
.10
.4
c
AVFP
2.08
5.87
3.35
37.1
Trailer GM 7



Car GM 7



Trailer GM 12



Car GM 12



    a)  Volume in the Aitken nuclei mode, ym /cm


                                       3   3
    b)  Volume in accumulation mode, ym /cm


                                                     3   3
    c)  Fine particle volume = AVFP = AVAN + AVAC, ym /cm
                            Table II



            Average Volumes Added to the Nuclei Mode

          (AVAN) and the Accumulation Mode  (AVAC) for

            the Car Outside Compared to the EPA Van



           AVAN    AVAC    AVTOT    AVAN/AVATOT
Car
EPA Van
8.57
1.49
3.62
0.63
12.19
2.12
.70
.70
           (All volumes in ym /cm )
                                97

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           reee
                                                          109
Figure 1. Example of a distinctly  trimodal volume size distribution
          measured by the EPA  trailer in situ aerosol instruments
          during GMPG Run 15 on  10/29/75.   The size ranges measured
          by each instrument are shown.   Note the excellent matching
          between the instruments  where  they overlap.  The geometric
          mean sizes and geometric standard deviations are typical
          of those measured during the test periods.
                       DURING RUN 10/29/75
                    —	 BACKGROUND AFTER RUN 10/29/79
                                                10
                                                        100
                                   DP(/im)
  Figure 2. Trimodal model distributions measured  by the EPA trailer
            during GMPG Run 15 on 10/29/75.   The model distributions
            were obtained by fitting  the data shown in Figure 1.  Note
            that during the test the  accumulation  and coarse particle
            modes (center and right-hand modes) have not changed
            significantly from the  background conditions.  On the other
            hand, practically all of  the volume of the nuclei mode  (left-
            hand mode) is contributed by the cars  on the roadway.
                                 98

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            E
            a.
            Q.
            Q
                               ill - 1 -- ! I | N ll| - 1 - 1
                                DIFFERENCE DISTRIBUTIONS
                                  RUN - BKGND
                                      A GMPG 12 ON 10-23-75
                                         WDIR'186'
                                        GMPG 10 ON 10-21-75
                                         WOIR -226°
                0 003
                      0 01
                          0 03
                               01
                                    03
Figure 3.  Shown are different distributions calculated  from averages
           of  the size distributions  measured by the car on  the
           roadway during the indicated runs and measurements of
           background aerosol made before and after the  test period.
           Included in the figure are the volume (V),  (V), mean
           geometric size (DPG), and  geometric standard  deviation for
           the resulting modes.  These are based on a  fit  of the
           difference data using the  log-normal fitting  procedures.
                                    99

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1.  Task Title:  Sources and Trace Metals in Urban Aerosols.

2.  Sub-Task Title:  Freeway Aerosol  Studies

3.  Objectives:

         Design a measurement program capable of determining  trace aerosol  pollutants
    along roadways which can be used  to evaluate:  time nariation patterns  of elements
    analyzed; area and height dependence; extent of mixing with local  and regional
    components of aerosol  pollutants; and baseline assessment along an urban freeway.

4.  Institution:  Department of Oceanography, Florida State University
                  Tallahassee, Florida  32306
    Investigator:  John W.  Winchester

5.  EPA Project Officer:  Ronald K.  Patterson

6.  Progress:

         Jensen-Nelson samplers ("Streakers") were placed at  five locations along a
    roadway running through a residential neighborhood in Tallahassee, Florida.   Four
    samplers were located  around a nearby house, and one was  located inside the  house.
    Samplers 1 and 2 were  located 7 meters from the roadway,  and 2 to  5 meters above
    the ground, respectively.  Sampler 3 was 7 meters from the roadway, behind a hedge.
    Sampler 4 was 24 meters from the  roadway and 15 meters away from an adjacent sam-
    pler (#5), which was located inside a closed, air conditioned house. All  samplers
    were collected continuously over  a one-week period on 0.4pm pore size Nuclepore
    filter strips.  The Streaker samples were analyzed by Proton induced X-Ray Emission
    (PIXE) techniques.  Each 2-hour sample collected by each  Streaker  underwent  85
    separate analyses.  The X-Ray spectra were fitted by computer and  reduced for S,~"""~
    Cl, K, Ca, Fe, Br, and  Pb, with sensitivities between 10-100ng.

         Time variations over 2-hour  sampling periods showed  daily variations in
    Pb, Br, Fe, and Ca.  Pb and Br gave constant ratios (0.235 ± 0.069) and were
    correlated with traffic patterns.  Fe and Ca variations followed the Pb and  Br
    patterns and were thought to be generated from roaddust mechanically disturbed
    by automotive traffic.   Sulfur and chloride did not show  diurnal variation.
    Chlorine concentrations were generally quite low except in sea breezes.

         Table I presents  the mean concentrations and standard deviations for the
    elements determined at the five sampling locations.  Locations 1 and 2  correlate
    well and show little height differentiation.  Location 3  shows the effects of
    filtration by the hedge.  Location 4 shows lower aerosol  concentrations because
    of diffusion.  Location 5 shows low concentrations for all elements except
    potassium,which is being generated inside the house.

         Aerosol analysis of short sampling periods allows one to make conclusions
    on the behavior of trace elements in the atmosphere and their potential effects
    on human receptors.  Elemental concentrations as a function of time and diurnal
    variation patterns give evidence  of local emissions (in this case  for automotive
    emissions), and their relationships to human activity.  Because of the  short
    sampling times, some of this study's data show large variations which indicate
    aerosol input from other sources  and/or meteorological effects.  Therefore,  the
    prediction of pollutant uptake by inhalation has to be assessed in conjunction
    with the following considerations:  a.) the occurrence of the elements  over short


                                       100

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    time periods, representative of human exposure;  b)  the exposure  of humans
    relative to the cycles of their daily activity.   The results  of  this  study
    have been applied to a predictive model  to show  the consequences of a
    proposed widening of the roadway.

            In another study under this sub-task title, PIXE analysis was used  to
    assess the aerosol sulfur baseline along an urban freeway.   In September
    1974, before the 1975 vehicles equipped  with catalytic emission  control
    devices were in use, a sampling plan was developed  which used six Battelle-
    type cascade impactors to fractionate aerosols collected during  five  selected
    2-hour intervals, near the San Diego Freeway in  Los Angeles,   these impactors
    were operated simultaneously on three towers at  2 and 7 meters above  road
    level, 35 meters upwind, and 35 meters downwind  of the traffic lanes.  Par-
    ticles as a function of time were sampled continuously for  100 hours  from
    three 7-meter heights using time-series  "Streaker"  filter samplers with two-
    hour time resolution.  All samplers were analyzed for S, Cl,  K,  Ca, Fe, Br,
    and Pb using PIXE analysis.

            Table 2 shows results from the first sampling period, 1530-1730,
    Thursday, 12 September 1974,  Clearly the freeway is a major  source of lead,
    not sulfur.  Streaker data show parallel fluctuation in sulfur at all three
    sites, downwind and upwind of the freeway.  This supports the hypothesis that
    particulate sulfur is non-automotive in  origin.

            The abundance of lead permits a  prediction  of the expected increase  in
    elevation of particulate sulfur concentrations along roadways when non-catalytic
    automobiles burning leaded gasoline are  replaced by catalytic automobiles
    burning non-leaded fuel.  If the following information is available . prediction
    of sulfate increases will be more effective.

    (1)  The relative contents of lead in gasoline now and of sulfur in gasoline
    to be used with catalytic converters.  As a national average, both values are
    about 0.05% by weight.

    (2)  The relative emission factors for lead and  sulfate aerosol  from  automotive
    sources.

    (3)  The relative particle size distributions of present automotive lead aerosol
    and catalytic sulfate aerosol; their response to relative humidity, particle
    coagulation during aging, and other atmospheric  effects,

7.   Publications and Presentations:

    1.  G.G. Desaedeleer, J.W. Winchester, J.O, Pillotte, J.W,  Nelson, and
    H.A. Moffitt.  Proton Induced X-Ray Emission Analysis of Roadway Aerosol
    Time Sequence Filter Samples For Pollution Control  Strategy.   JAEA
    Conference Proceedings, Vienna, Austria, March,  1976.  (In  Press).

    2.  K.R. Akselsson, K.A. Hardy, G.G. Desaedeleer, J.W. Winchester, W.W. Berg,
    T.B. VanderWood, J.W. Nelson.  1976.  X-Ray Techniques For  Aerosol Sulfur
    Baseline Assessment Along An Urban Freeway.  Advances in X-Ray Analysis ,19:415-425,

8.   Plans:  This grant is complete and final report  will be forthcoming.
                                      101

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                           Sampling Sites
                              TABLE I
     Weekly mean values and standard deviation  of  the  distribution -
expressed in ng/m  and in % (standard deviation/mean value)  respectively
of S, Cl, K, Ca, Fe, Br and Pb concentrations measured over  one week
in two hours sampling periods.

Element
(ng/m3)
                                                              3
        S     725.±360.(49.7)      689.±383.(55.6)      743.±441.(59.4)
        Cl    482.±591.(123.)      414.±587.(142.)      380.±534.(154.)
        K     <58.± 22.(37.9)      <50.±  16.(32.0)      <54.± 25.(46.3)
        Ca    288.±253. (87.8)      247.±143 . (57.9)      172.±115.(66.9)
        Fe    156+143.(91.0 )      147.±  88.(59.9)      126.± 75.(59.5)
        Br    104.±64.(61.5)        87.+  46.(52.9)       61.± 30.(49.2)
        Pb    450.±240.(52.6)      387.±179.(46.3)      285.±134.(47.0)
                      4                      5
          S     432.+ 280. (64.8)      236.±144.(61,0)
          Cl    233.±339.(146.)      111.±109.(98.2)
          K     <52.±  60.(115.)     <203.±287. (141.)
          Ca      92.+  63. (68.5)      <36.±  43. (119.)
          Fe      81.±  47.(58.0)       26.±  40.(154.)
          Br      38.±  16.(42.1)       15.±   7.(46.4)
          Pb    174.±  80.(46.0)       63.+  28.(44.4)
                                    102

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                              TABLE TT




 Sulfur and lead concentrations found at Freeway Sites, A, C, D,
Stage
6*
5
4
3
2
1
Size Range
<0.25
0.25-0.50
0.5-0.50
1.0-2.0
2.0-4.0
4.0-
A
1640
207
117
105
90
75
3
S ng/m
C
1680
205
211
124
102
67
3
Pb ng/m
D
1790
308
288
147
99
76
A
95
46
29
26
26
21
C
1410
145
189
237
216
40
D
1200
277
176
246
198
61
*Figures for stage 6 are not corrected for filter efficiency.
                                103

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1.  Task Title:   Dynamics of Automotive  Sulfate  Emissions.

2.  Objective:

         To apply an aerosol  dynamic  model  to estimate  the  size  and  composition
    of ultrafine sulfuric acid aerosols  generated  by  catalyst-equipped  automo-
    biles.
3.  Institution:   University of Texas,  Austin,  Texas
    Investigators:   J.R.  Brock, K.  de  Bower,  and  S.H,
                                  Suck
4.   EPA Project Officer:   J.L.  Durham

5.   Progress:

         A numerical  model (see Task) has been  applied  to  represent dispersion
    and advection of sulfate aerosol  from automobiles  on a ten  lane expressway
    for winds  perpendicular and parallel  to the expressway.   The  automotive
    sulfate aerosol  interacts through coagulation  with  the ambient aerosol.
    In addition, the size distribution changes  with  humidity.   Through use of
    a reactive dispersion model termed EPOSOD,  we  have  also studied the
    reaction of the  sulfate highway plume with  ambient  levels  of  ammonia for
    very stable meteorological  conditions (Figure  1).

6.   Puolications , Presentations, Thesis :
        Suck, S.H.
        Emissions.
        1976.
K. de Bower and J.R.  Brock.   Dynamics of Automotive Sulfate
A.C.S. Symposium on Automotive Sulfate Emissions, August
    Plans:
        This task is complete.
                                     104

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OO'OfrZ
00'OOZ
                                                                          00'0
                                      '(a)DO1O/Wa
                                     105

-------
1.   Task Title:   The General  Motor-Environmental  Protection Agency
                  Sulfate Dispersion Experiment in October 1975 at the
                  General Motor,  Milford Test Track

2.   Objective:

          To measure roadside  sulfate exposures from a fleet of 100
     percent-catalyst-equipped vehicles.

3.   Institution:  EPA-ERC, ESRL-ARB
     Investigator:  L.L.  Spiller, M. Miller

4.   EPA Project Officer:  W.E.  Wilson

5.   Progress:

          EPA investigators measured for sulfates, sulfuric acid,  sulfur
     dioxide and particle size at towers and in mobile laboratories at
     several distances just off the test track.  It has been established
     that most  of the aerosol  mass emitted from the air injection  catalyst
     equipped vehicles was in  the form of ultrafine sulfur aerosol in
     the size range between 0.01  and 0.1 ym.  The  background measurements
     before and after operation of the vehicle fleet and the ultrafine
     sulfur-containing aerosol was almost completely absent.

          Sulfuric acid was measured inside the equipped vehicle while
     it was running in the test track.  More than  two-thirds of the sulfate
     emitted by the vehicle was measured as sulfuric acid 20 meters off
     the test track.

6.   Publications, Presentations, Theses:

     General Motors Sulfate Dispersion Experiment:  Summary of EPA
       Measurements
7.   Plans:
          Test is completed and results evaluated.
                                106

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1 •   Task Title:   Atmospheric Behavior of Catalyst-Generated Aerosols  from
    Source to Receptor.

2.   Objective:

         To predict the  deposition efficiencies of sulfuric acid  aerosols
    (0.01 to 10  pm) in the lungs,

3.   Institution:  ARB-ESRL
    Investigator:  J.L.  Durham and R. Orr (Student Aide)

4.   EPA Project  Officer:  W,E.  Wilson

5.   Progress:

         Catalyst-equipped automobiles emitted sulfuric acid, which nucleates
    and forms sulfuric acid solution droplets in the atmosphere.   Whitby made
    measurements of the  roadway size distribution during  the GM-EPA experiment
    (November 1975).  He found a mode in the volume distribution  with a mean
    geometric diameter of 0.033 urn and geometric standard deviation of 1.6.
    Such small sizes of sulfuric acid solution droplpt.s could exhibit growth
    and lung deposition  behavior that is different from chat of larger droplets
    Calculations of growth were performed for which it, was assumed that the
    final size of an inhaled droplet is determined by the dry mass of sulfuric
    acid and the Kelvin  equation (which relates vapor pressure to surface
    curvature).   The relative humidity of the lungs was taken to  be 99%.  The
    deposition was calculated for the nasopharnyx (NP), tracheobronchial (TB),
    and pulmonary (P) compartments using the ICRP values  for a tidal  volume
    of 1450 cm3.

         Typical values  are given in Table 1 for the final size and acid
    normality of ambient sulfuric acid solution droplets  (rh = 50%) that
    are inhaled  (rh = 99%).

         For the value of 0.035 um (n the roadway gmd), the concentration  is
    lowered from lli^ in  atmosphere (rh = 50%) to 1N_ in the lungs  (rh  = 99%).
    The final concentration of smaller diameters will be  greater.  Ambient
    droplets with diameters greater than about 0.5 pm will have concentrations
    of about 0.2N_ in the lungs.  Thus, it should be expected that fresh
    roadway sulfuric acid droplets will have a concentration of 4-25  times
    greater than aged aerosol.

         For Whitby's measurements, the dry sulfuric acid mass distribution
    as a function of solution droplet size is shown in Figure 1 for relative
    humidities of 50% and 99%.   Although the increase in  relative humidity
    causes the droplets  to grow, there is little effect on the lung deposition,
    as can be seen in Table 2.

         Because the sensitive tissue of the pulmonary is the receptor of
    these sulfuric acid  droplets, immediate action is warrented to define  the
    extent on health hazard.
                                     107

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6,  Publications, Presentations,  and  Thesis:

         This work was  presented  at the  ACS  San  Francisco,  October,  1976
    A full  report will  be published in  the ORD series.

7.  Plans:   Project is  complete.
                                    108

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           TABLE 1.   Concentration of Droplets  and Dilution  Factors
Mass H.,50,
                                                 Growth Factor ct=
Relative Humidity = 50%    Relative Humidity = 99%      Radius at 99%    Dilution
in droplet, g.
ID'18
1C'17
ID'16
ID'15
ID'14
ID'13
Radius* , um
0.0073
0.016
0.035
0.075
0.16
0.35
Mortality
13
12
11
11
11
11
Radius*,pm
0.010
0.027
0.070
0.18
0.42
1.0
Normality**
S
2
1
0.8
0.6
0.5
Radius at 50"o
1.4
1.7
2.0
2.4
2.7
2.9
Factor
0.13
0.20
0.12
0.072
0.051
0.041
                                           109

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TABLE 2.   Deposition calculated from the 99f^ and 50% relative
          humidity sulfuric acid dry mass distributions.
                                           Dry_Mas.s H2sn.t,  mg/m3

      Relative Humidity:                       99%         50%

      0.01  ym < D < 10 ym

              Total inhaled                   20          20
              Pulmonary deposition             10          12
              Tracheabronchial  deposition       1           1
              Nasopharynx deposition           2           0

                      Total deposition        13          13



      D < 0.1  ym

              Total  inhaled                   13         11
              Pulmonary deposition              7           9
              Tracheabronchial  deposition       1            1
              Nasophyarynx  deposition           0           0

                      Total  deposition         8         10
                                  no

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                              APPENDIX A

            ARB Projects funded by the Federal Interagency
          Energy/Environment Research and Development Program
PROJECT MISTT

     Direction of MISTT Field Studies, by W.E. Wilson

     Management of MISTT, by W.E. Wilson 	
     Aircraft Monitoring and Analysis for an Aerosol
       Characterization Study in St. Louis, by D.L. Blumenthal .
     Project MISTT Field Program, by R.B. Husar
     Formation of Atmospheric Aerosols—Aerosol Characteristics
       Measured at Glasgow, MO and in the St. Louis Urban Plume
       during the Summer 1975, by K.T. Whitby  	 ,
     Formation of Atmospheric Aerosols—Coal Fired Power Plant
       Plume Studies in St. Louis, Summer 1976, by K.T. Whitby .

     Project MISTT - Synoptic Scale Haziness and Air Pollution,
       by R.B. Husar 	

     Processing and Analysis of Project MISTT Data, by
       R.B. Husar  	

     St. Louis Plume Study - Halocarbon and Hydrocarbon
       Measurements, by R.A. Rasmussen 	
     Application of Statistical and Mathematical Methods
       to Air Pollution Problems, by J.H. Overton  . . .
     Atmospheric Boundary Layer Measurements in Project
       MISTT; MISTT-II, by B. Hicks  	 ,
     Field Sampling and Analysis of Airborne Particulate
       Material in Conjunction with MISTT, by P.T. Cunningham

     Formation of Atmospheric Aerosols—Aerosols Produced
       by Combustion, by K.T. Whitby 	
     Aerosol Formation and Removal in Plumes, by J.R. Brock  .  .

     Mobile Laboratory Operations in Support of Project MISTT,
       July-August 1975, by T.G. Ellestad  	
     Gas Calibration Support for 1976 MISTT Summer Field Program,
       July 1976, by T.G. Ellestad   	
                                  Ill

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Data Processing Support for 1976 Summer Field Program,
  July 1976, by K. Fuchs  	
Relationships among Ground-level Sulfate Concentrations,
  Visibility Reduction, and Meteorological Conditions,
  by D. Fondario  	
Mesoscale Sulfate Concentration Study, by R.K. Patterson
                             112

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                               APPENDIX B

         PUBLICATIONS, PRESENTATIONS, AND THESIS LISTING INDEX
 1970
1.  Ensor, D.S. and A.P. Waggoner.  1970.  Angular Truncation Error in the
    Integrating Nephelometer.  Atmos. Environ.  4:481-487.

1971

2.  Brock, J.  1971.  On Size Distributions of Atmospheric Aerosols.
    Atmos. Envir.  5:833-841.

3.  Brock, J.  1971.  Models for Asymptotic Size Distributions for Atmospheric
    Aerosols.  J.  of  Colloid and Interface Sci.  37:907-911.

4.  Ensor, D.S., W.M. Porch, M.J.  Pilat  and R.J. Charlson.  1971.  Influence
    of Atmospheric Aerosol  on Albedo.  J. Applied Meteor.  10:1300-1306.

5.  Friedlander, S.K.   1971.  The  Characterization of Aerosols Distributed
    with Respect to Size and Chemical Composition.   J. Aerosol Sci.  2:331.

6.  Waggoner,  A.P. and  R.J. Charlson.  1971.  Stimulating the Color of
    Polluted Air.  Applied  Optics.  10:957.

7.  Zeigler, C.S., R.J. Charlson and S.H. Forler.  1971.  Mt. Rainier:  Now
    You See  It, Now You Don't.  Weatherwise.  24:115-119.

1972

8.  Brock, J.  1972.   Condensational Growth  of Atmospheric Aerosols.  J.  of
    Colloid  and Interface  Sci.  39:32-36.

9.  Charlson,  R.J., D.S. Covert, Y. Tokiwa  and P.K.  Mueller.  1972.  Multi-
    wavelength Nephelometer Measurements in Los Angeles  Smog Aerosol III:
    Comparison to  Light Extinction by NO .  J. Colloid and Interface Sci.
    39:260-265.                          *

10.  Covert,  D.S.,  R.J.  Charlson and N.C. Ahlquist.   1972.  A Study of  the
    Relationship  of Chemical  Composition and  Humidity to Light Scattering
    by Aerosols.   J.  Applied Meteor.   11:968-976.

11.  Ensor, D.S.,  R.J. Charlson, N.C. Ahlquisti K.T.  Whitby, R.B.  Husar  and
    B.Y.H. Liu.   1972.  Multiwavelength  Nephelometer Measurements in Los
    Angeles  Smog 'I:   Comparison of Calculated and Measured Light  Scattering.
    J. Colloid and Interface  Sci.   39:242-251.

12.  Harrison,  H.,  J.  Herbert  and A. Waggoner.  1972. Mie Theory  Computations
     of Lidar and  Nephelometric Scattering Parameter  for  Power-Lav Aerosols.
     Applied  Optics.   11:2880-2885.

13.   Husar,  R.B.   1972.   On the Formation of Photochemical Aerosols.  In:
     Proceedings of International Workshop on Nucleation Theory  and its
     Applications.  Atlanta, GA, April 10-12,  1972.

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14.  Husar, R.B., K.T. Whitby,  B.  Liu and N.  Barsic.   1972.   The Minnesota
     Aerosol Analyzing System used in the Pasadena Smog Project.  J. Colloid
     and Interface Sci.  39:211-224.

15.  Judeikis, H.S. and S.  Siegel.  1972.  Particle-Catalyzed Oxidation of
     Atmospheric Pollutants.   The  Aerospace Corp.   El Segundo, CA.
     ATR-73(7256)-l.

16.  Lin, M.J., D.P. Johnson and J.H. Lunsford.   1972.   The  EPR Spectra of
     COS" and CS~ on Magnesium Oxide.  Chem.  Phys. Letters.   15:412-414.

17.  Miller, M.S., S.K. Friedlander and G.M.  Hidy.  1972.  A Chemical
     Element Balance for the Pasadena Aerosol.   J. Colloid Interface Sci.
     39:165-176.

18.  Schoonheydt, R.A. and J.H. Lunsford.  1972.  An Electron Paramagnetic
     Resonance Study of SO" on Magnesium Oxide.   J. Phys.  Chem.  76:323-328.

19.  Schoonheydt, R.A. and J.H. Lunsford.  1972.  Infrared Spectroscopic
     Investigation of the Adsorption and Reactions of SO,,  and MgO.  J.
     Catal.  26:261-265.

20.  Thielke, J.F., R.J. Charlson, J.W. Winter,  N.C.  Ahlquist, K.T. Whitby,
     R.B. Husar and B.Y.H.  Liu.  1972.  Multiwavelength Nephelometer
     Measurements in Los Angeles Smog Aerosols  II:  Correlation with Size
     Distributions, Volume Concentrations and Broad Band Light Scattering.
     J. Colloid and Interface Sci.  39:252-259.

21.  Waggoner, A.P., N.C. Ahlquist and R.J. Charlson.  1972.  Measurement:
     of the Aerosol Total Scatter-Backscatter Ratio.   Applied Optics.
     11:2886-2889.

22.  Waggoner, A.P., R.J. Charlson and N.C. Ahlquist.  1972.  Comment on
     "On the Brown Color of Atmospheric Haze" by H. Horvath.  Atinos. Environ.
     6:143-144.

23.  Whitby, K.T., R.B. Husar and B.Y.H. Liu.  1972.   The Aerosol Spectra of
     Los Angeles Smog.  J.  Colloid and Interface Sci.  39:177-204.

24.  Whtiby, K.T., B.Y.H. Liu and R.B. Husar.  1972.   Physical Mechanisms
     Covering the Dynamics of Los Angeles Smog Aerosols.  J. Colloid and
     Interface Sci.  39:136-164.

25.  Wilson, W.E., W.E. Schwartz and G.W. Kinzer.   Haze Formation:  Its
     Nature and Origin.  EPA-CPA 70-Neg. 172, U.S. Environmental Protection
     Agency, RTP, NC, 1972.  71pp.

1973

26.  Anderson, J.A., D.L. Blumenthal and G.J. Sem.  Characterization of
     Denver's Urban Plume Using an Instrumented Aircraft.   Brown Cloud of
     Denver.  The Denver Air Pollution Study, Proceedings of a Symposium.
     EPA,  RTP, NC,  1973.
                                   114

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27.  Bhardwaja, O.S.,  R.J. Charlson, A.P. Waggoner and N.C. Ahlquist.  1973.
     Rayleigh Scattering Coefficients of Freon-12, Freon-22, and CO,, Relative
     to that of Air.  Applied Optics.  12:135-136.

28. ' Brock, J.   1973.   Comments of Theories of Aerosol Charging.  J. of
     Colloid and Interface Sci.  39:418-420.

29.  Brock, J.  and M.S. Wu.  1973.  Field Changing of Aerosols.  J. of
     Colloid and Interface Sci.  45:106-114.

30.  Crow, L.W.  Airflow Study Related to EPA Field Monitoring Program
     Denver Metropolitan Area Nov., 1973.  In:  Denver Air Pollution Study-
     1973.  EPA-600/9-76-007a.  (1:3-29), U.S. Environmental Protection
     Agency, RTP, NC,  1976.

31.  Frank, R., C.E. McJilton and R.J. Charlson.  Sulfur Oxides and Particles:
     Effects on Pulmonary Physiology in Man and Animals.  Presented at:
     Conference on Health Effects of Air Pollutants, NAS, Washington, D.C.,
     Oct. 3-5,  1973.

32.  Friedlander, S.K., 1973.  Chemical Element Balances and Identification
     of Air Pollution Sources.  Environ. Sci. Tech.  7:235-240.

33.  Hedgpeth,  H., S.  Siegel, T.B. Stewart and H.S. Judeikis.  1973.
     Cylindrical Flow Reactor for the Study of Heterogeneous Reactions of
     Possible  Importance in Polluted Atmospheres.  The Aerospace Corp.
     El Segundo, CA, ATR-73(7256)-4.  21pp.

34.  Heisler,  S.L., S.K. Friedlander and R.B. Husar.  1973.  The Relationship
     of Smog Aerosol Size and Chemical Element Distributions to Source
    .Characteristics.   Atmos. Environ.  7:633-649.

35.  Johansson, T.B.,  J.W. Nelson, R.E. Van Grieken, K.R. Chapman and J.W.
     Winchester.  Elemental Composition of North Florida Aerosol Size
     Fractions.  In:  American Chemical Society 166th National Meeting.
     Chicago, August 26-31, 1973.  Abstract COLL 059.

36.  Johansson, T.B.,  J.W. Nelson, R.E. Van Grieken and J.W. Winchester.
     1973.  Elemental Analysis of Aerosol Size Fractions by Proton Induced
     X-Ray Emission.  In:  Transactions, American Nuclear Society.  17:103.

37.  Jones, P.W.  The Analysis of Ambient Denver Air for Organic Vapors
     Including Carcinogenic POM Compounds.  In:  Denver Air Pollution Study
     1973.  EPA-600/9-76-007a.  (1:31-50), U.S. Environmental Protection
     Agency, RTP, NC,  1976.

38.  Judeikis,  H.S. and S. Siegel.  1973.  Efficiency of Gas-Wall Reactions
     in a Cylindrical Flow Reactor.  The Aerospace Corp.  El Segundo, CA.
     ATR-73(7256)-2.

39.  Judeikis,  H.S. and S. Siegel.  1973.  Particle-Catalyzed Oxidation of
     Atmospheric Pollutants.  Atmos. Environ.  7:617-631.
                                   115

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40.  Lin, 'C., M.B.  Baker and R.J.  Charlson.   1973,   Absorption Coefficient
     of Atmospheric Aerosol:  A Method for Measurement.   Applied Optics.
     12:1356-1363.

41.  Lunsford, J.H. and D.P. Johnson.   1973.   Electron Paramagnetic Resonance
     Study of S" Formed on Magnesium Oxide.   J.  Phys.  Chem.   58:2079-2083.

42.  McJilton, C.,  R.  Frank and R.J. Charlson.   1973.   The Role of Relative
     Humidity in the Synergistic Effect of SOI Aerosol Mixture on the Lung.
     Science.  182(4111):503-504.

43.  Middleton, P.B. and J.R. Brock.  1973.   The Denver Brown Cloud.  In:
     Denver Air Pollution Study-1973.   EPA-600/9-76-007a.  (1:101-140),  U.S.
     Environmental  Protection Agency,  RTP, NC, 1976.

44.  Miller, D.F.,  W.E. Schwartz,  J.L. Gemma  and A.  Levy.  Haze Formation:
     Its Nature and Origin.  EPA-650/3-75-010, U.S.  Environmental Protection
     Agency, RTP, NC,  1973.

45.  Miller, D.F.,  W.E. Schwartz,  P.W. Jones, P.W.  Joseph, C.W. Spicer,
     C.J. Riggle and A. Levy.  Haze Formation:   Its  Nature and Origin.
     EPA-650/3-74-002, U.S. Environmental Protection. Agency,  RTP, NC,
     1973.

46.  Porch, W.M., D.S. Ensor, R.J. Charlson and  J.  Heintzenberg.  1973.   Blue
     Moon:  Is this a Property of Background  Aerosol?  Applied Optics.
     13:34-36.

47.  Russell, P.A.  and C.O. Ruud.   1973.  An  Analysis of Particulates From
     the Denver Urban Plume Using Scanning Electron Microscopy and Energy
     Dispersive X-Ray Spectrometry.  In:  Denver Air Pollution Study-1973.
     EPA-600/9-76-007a.  (1:165-182),  U.S. Environmental Protection Agency,
     RTP, NC, 1976.

48.  Stewart, T.B.   1973.   Positive Displacement Gas Circulating Pump.  The
     Aerospace Corp.  El Segundo,  CA.   ATR-73(7256)-3.  7pp.

49.  Stewart, T.B.   1973.   Positive Displacement of Gas Circulating Pump.
     Rev. Sci. Instrum.  44:1144.

50.  Taarit, B.Y. and J.H. Lunsford.  1973.   Electron Paramagnetic Resonance
     Evidence for the Formation of SO" by the Oxidation of SO" on MgO.  J.
     Phys. Chem.  77:1365-1367.

51.  VanGrieken, R.E., T.B. Johansson, J.W. Nelson and J.W. Winchester.
     Charged Particles in Elemental Analysis: X-Ray Emission and Elastic
     Scattering.  In:  American Chemical Society 166th National Meeting,
     Chicago, August 26-31, 1973.  Abstract NUCL021.

52.  Waggoner, A.P.  The Brown Cloud of Denver.   In:  The Denver Air
     Pollution Study,  Proceedings of a Symposium.   EPA-600/9-76-007b,
     U.S. Environmental Protection Agency, RTP,  NC,  1973.  (In Press)
                                  116

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53.  Waggoner, A.P., M.B. Baker and R.J. Charlson.  1973.  Optical Absorption
     by Atmospheric Aerosols.  Applied Optics.  12:896.

1974

54.  Akselsson, R. , C. Orsini, D.L. Meinert, T.B. Johansson, R.E. Van Grieken,
     H.C. Kaufman, K.R. Chapman, J.W. Nelson and J.W. Winchester.  1974.
     Application of Proton Induced X-Ray Emission Analysis to the St. Louis
     Regional Air Pollution Study.  Advances in X-Ray Analysis.  18.

55.  Blumenthal, D.L., J.A. Anderson and G.J,. Sem.  1974.  Characterization
     of Denver's Urban Plume Using an Instrumented Aircraft.  APCA Paper
     74-266.  Denver, CO.

56.  Brock, J. and N. Marlow.  1974.  Calculations of Bipolar Charging of
     Aerosols.  J. of Colloid and Interface Sci.  51:23-31.

57.  Brock, J. and N. Marlow.  1974.  Charged Aerosol Particles and Air
     Pollution.  Environ. Letters.

58.  Brock, J., J. Bricard, G. Madelaine and M. Pourprix.  1974.  Repartition
     de las Charge d'Espace Au Voisinage d'un Faisieau de Particules.  C.R.
     Acad. Sc. Paris.  278:1974.

59.  Charlson, R.J., W.M. Porch, A.P. Waggoner and N.C. Ahlquist.  1974.
     Background Aerosol Light Scattering Characteristics:  Nephelometric
     Observations at Mauna Loa Observatory Compared with Other Remote
     Locations.  Tellus.  26(3):345-360.

60.  Charlson, R.J., A.H. Vanderpol, A.P. Waggoner, D.S. Covert and N.C.
     Ahlquist.  1974.  Sulfuric Acid.  Ammonium Sulfate Aerosol:  Optical
     Detection in the St. Louis Region.  Science.  184(4133):156-158.

61.  Grosjean, D. and S.K. Friedlander.  1974.  Gas-Particle Distribution
     Factors for Organic and Other Pollutants in  the Los Angeles Atmosphere.
     Submitted to:  APCA J.

62.  Hedgpeth, H., S. Siegel, T.B. Stewart and H.S. Judeikis.  1974.
     Cylindrical Flow Reactor for the Study of Heterogeneous Reactions of
     Possible  Importance in Polluted Atmospheres. . Rev. Sci. Instrum.
     45:344.

63.  Husar, R.B., D.L. Blumenthal, J. Anderson and W.E. Wilson.  The
     Urban Plume of St. Louis.  Proc. Div. of Environmental Chemistry, ACS.
     Los Angeles, CA, March 28-April 5, 1974.

64.  Jensen, B. and J.W. Nelson.  Novel Aerosol Sampling Apparatus for
     Elemental Analysis.  In:  Proc. Conf. Nucl. Techniques in Environ.
     Research.  Columbia, MO, July 29-31, 1974.

65.  Johansson, T.B., R.E. Van Grieken and J.W. Winchester.  1974.  Inter-
     pretation of Aerosol Trace Metal Particle Size Distributions.  In:
     Proc. Conf. Nucl. Techniques in Environ. Research.  Columbia, MO,
     July 29-31, 1974.


                                   117

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66.  Johansson, T.B., R.E. Van Grieken and J.W.  Winchester.   1974.  Marine
     Influences on Aerosol Composition in the Coastal Zone.   J.  De Recherches
     Atmos.  14 pp.

67.  Lunsford, J.H.  Structure and Reactivity of Adsorbed Oxides of Sulfur.
     EPA-650/3-74-006, U.S. Environmental Protection Agency,  RTF, NC, 1974.

68.  Nelson, J.W., I. Williams, T.B.  Johansson,  R.E. Van Grieken, K.R.
     Chapman and J.W. Winchester.  Elemental Analysis of Aerosols Using Proton
     Scattering.  In:  IREE Trans. Nucl.  Sci., NS-21:  618-621,  February 1974.

69.  Rao, K.V. and J.H. Lunsford.  1974.   An Electron Paramagnetic Resonance
     Study of SOI and SOT Ions on Vanadium Oxide Supported on Silica Gel.
     J. Phys. Chem.  78:649-651.

70.  Stewart, T.B. and J.S. Judeikis.  1974.  Measurement of  Spatial Reactant
     and Product Concentrations in a Flow Reactor Using Laser-Induced
     Fluorescence.  Rev. Sci. Instrum.  45:1542.

71.  Van Grieken, R.E., T.B. Johansson and J.W.  Winchester.   1974.  Trace
     Metal Fractionation Effects Between Sea Water and Aerosols  from Bubble
     Bursting.  J. De Recherches Atmos.  11 pp.

72.  Winchester, J.W., D.L. Meinert,  J.W. Nelson, T.B. Johansson, R.E. Van
     Grieken, C. Orsini, H.C. Kaufman" and R. Akselsson.  Trace Metals in
     the St. Louis Aerosol.  In:  Proc. Conf. Nucl. Techniques in Environ.
     Research.  Columbia, MO, July 29-31, 1974.

1975

73.  Blumenthal, D.L. and W.H. White.  The Stability and Long Range Transport
     of Ozone or Ozone Precursors.  1975.  APCA Paper No. 75-07.4.  Boston, MA.

74.  Davidson, C.I., S.K. Friedlander and S.V. Bering.  The Deposition of
     Pb-Containing Particles from the Los Angeles Atmosphere.  In:  Proceedings
     of the Intnl. Conf. on Environ.  Sensing and Assessment.   Las Vegas, NV,
     1975.  Vol. 1.  3 pp.

75.  Desaedeleer, G.G. and J.W. Winchester.  1975.  Trace Metal  Analysis of
     Atmospheric Aerosol Particle Size Fractions in Exhaled Human Breath.
     Environ. Sci. and Tech.  9:971-972.

76.  Desaedeleer; G.G., J.W. Winchester,  R. Akselsson, K.A.  Hardy and J.W.
     Nelson.  Bromine and Lead Relationships with Particle Size  and Time
     Along an Urban Freeway.  In:  Proceedings of the International Nuclear
     and Atomic Activation Analysis Conference on Analytical Chemistry in
     Nuclear Technology.  Oak Ridge,  TN,  October 14-16, 1975.

77.  Draftz, R.G.  Similarities of Atmospheric Aerosols from Four Major
     U.S. Cities.  Presented at:  Eighth Aerosol Technology Meeting.  RTP,
     NC, October 1975.

78.  Durham, J.L., W.E. Wilson, T.G.  Ellestad, K. Willeke and K.T. Whitby,,
     1975.  Comparison of Volume and Mass Distributions for Denver Aerosols.
     Atmos. Environ.  9(8):717-722.

                                   118

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79.  Fox, D.L., J.E. Sickles, M.R. Kuhlman' and P.C. Reist.  1975.  Design
     and Operating Parameters for a Large Ambient Aerosol Chamber.  APCA J.
     25(10):1050-1053.

80.  Gartrell, G. and S.K. Friedlander.  1975.  Relating Particulate Pollu-
     tion to Sources:  The 1972 California Aerosol Characterization Study.
     Atmos. Environ.  9:279-298.

81.  Gillani, N.V. and R.B. Husar.  Mathematical Modeling of Air Pollution -
     A Parametric Study.  Presented at:  Proc. Second Federal Conference
     on the Great Lakes.  Argonne, 1L, March 25-27, 1975.

82.  Grosjean, D. and S.K. Friedlander.  1975.  Gas-to-Particle Distribution
     Factors for Organic and Other Pollutants in Los Angeles.  J. Air Poll.
     Control Assoc.  25(10):1038-1044.

83.  Husar, R.B.  Fine Particulate Standard:  An Assessment of the need
     and an attempt of its formulation.  Presented at:  Proc. ASME Air
     Pollution Div., Fourth Annual Symp.  St. Louis, MO, March 24-25, 1975.

84.  Husar, J.D., R.B. Husar and P.K. Stubits.  1975.  Determination of
     Sub-Microgram Amounts of Atmospheric Particulate Sulfur.  Anal. Chem.
     47 (12)-.2062-2065.

85.  Husar, R.B. and W.R. Shu.  1975.  Thermal Analyses of the Los Angeles
     Smog Aerosol.  J. Applied Meteor.  14(8):1558-1565.

86.  Johansson, T.B., R.E. Van Grieken, J.W. Nelson and J.W. Winchester.
     1975.  Elemental Trace Analysis of Small Samples by Proton Induced
     X-Ray Emission.  Anal. Chem.  47(6):855-859.

87.  Lin, M.J. and J.H. Lunsford.  1975.  Photooxidation of Sulfur Dioxide
     on the Surface of Magnesium Oxide.  J. Phys. Chem.  79:892-897.

88.  Nelson, J.W.  1975.  Application of Proton Induced X-Ray Emission
     Analysis to the St. Louis Regional Air Pollution Study.  Advances in
     X-Ray Analysis.  18:588.

89.  Nelson, J.W. and D.L. Meinert.  1975.  Proton Elastic Scattering
     Analysis-A Complement to Proton Induced X-Ray Emission Analysis of
     Aerosols.  Advances in X-Ray Analysis.  18:598.

90.  Nelson, J.W.  1975.  Automatic Time Sequence Filter Sampling of Aerosols
     for Rapid Multi-element Analysis by Proton Induced X-Ray Emission.
     Advances in X-Ray Analysis.  19:403.

91.  Nelson, J.W.  1975.  X-Ray Techniques for Aerosol Sulfur Baseline
     Assessment Along an Urban Freeway.  Advances in X-Ray Analysis.
     19:415.

92.  Vanderpol, A.H., F.D. Carsey, D.S. Covert, R.J. Charlson and A.P.
     Waggoner.  1975.  Aerosol Chemical Parameters and Air Mass Character
     in the St. Louis Region.  Science.  190.
                                   119

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 93.   Van Grieken,  R.E.,  T.B.  Johansson,  J.W. Winchester  and L.A.  Odom.
      1975.   Micro-Determination  of  Zirconium-Hafnium Ratios in  Zircons  by
      Proton Induced  X-Ray  Emission.  Anal.  Chem.   275:343-348.

 94.   Vaughan,  W.M.,  R.  Sperling, N.V.  Gillani  and  R.B. Husar.   Horizontal
      SOo Mass  Flow. Rate  Measurements in  Plumes:  A Comparison of  Correlation
      Spectrometer  Data with  a Dispersion and Removal Model.  In:   Proc.
      68th Annual Meeting,  APCA.  Boston,  MA, June  1975.

 95.   Winchester, J.W.   1975.   The Ocean  as  a Source of Particulate Matter.
      Nat'l  Acad. Sci. Report.   (In  Press).

 96.   Winchester, J.W.  Approaches to Evaluating Dry Deposition  of Atmospheric
      Aerosol Pollutants  onto Lake Surfaces.  In:   Proc.  First Specialty
      Symposium on  Atmospheric Contribution  to  the  Chemistry of  Lake Waters.
      Internat. Assoc. Great  Lakes Res.   September  28-October 2, 1975.

 1976

 97.   Akselsson, K.R., K.A. Hardy, G.G. Desaedleer,  J.W.  Winchester, W.W.
      Berg,  T.B. Vandervood and J.W. Nelson.  1976.  X-Ray  Techniques for
      Aerosol Sulfur  Baseline Assessment  Along  an Urban Freeway.  Advances
      in X-Ray  Analysis.   19:415-425.

 98.   Boueres,  L.C.S., F. Adams,  J.W. Winchester, C.Q. Orsini, J.W. Nelson,
      T.A. "Cahill and D.R.  Lawsen.   Sulfur and  Heavy Metals in South American
      Urban  and Nonurban Atmospheres.   Presented at: The World  Meteorological
      Organization  Technical  Conference on Atmospheric Pollution Measurement
      Techniques.  Gothenburg,  Sweden,  October  11-15, 1976.

 99.   Brock, J.  1976.   Simulation of Aerosol Kinetics.   J. of Colloid and
      Interface Sci.   54:249-264.

100.   Brock, J.  1976.   Studies in Aerosol Dynamics: The Denver Brown Cloud.
      Environmental Monitoring Series,  EPA.   (In Press).

101.   Brock, J.  1976.   Simulation of Aerosol Dynamics.   EPA Ecological
      Research  Series.   (In Press).

102.. Brock, J.  1976.   The Houston  Urban Plume Study.  EPA Ecological
      Research  Series.   (In Press).

103.   Brock, J., K. DeBower and S. Suck.   Dynamics  of Automotive Sulfate
      Emissions.  In:  Proceedings of A.C.S. Symposium  on Automotive Sulfat-3
      Emissions. August 1976.

104.   Brock, J. and P.B.  Middleton.   1976.  Dynamic Model for Urban Particu-
      late Pollution.  Submitted to: Atmos. Environ.

105.   Cunningham, P.T.  and S.A. Johnson.   1976.  Spectroscopic Observation
      of Acid Sulfation  Atmospheric  Particulate Samples.   Science.  191:77-79.

106.   Dannevik, W.P., S.  Frisella, L.  Granat and R.B. Husar.   S02 Deposition
      Measurements  in the St. Louis  Region.   Preprint:   Third  Symp. on Atmos-
      pheric Turbulence, Diffusion  and  Air Quality, AMS,  Raleigh, NC,
      October 19-22,  1976.

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107.  Desaedeleer, G.G., J.W. Winchester and K.R. Akselsson.  Monitoring
      Aerosol Elemental Composition in Particle Size Fractions for Predicting
      Human Respiratory Uptake.  Presented at:  International Conference on
      Particle Induced X-Ray Emission and its Analytical Application.  Lund,
      Sweden, August 23-26, 1976.

108.  Desaedeleer, G.G., J.W. Winchester, J.O. Pillotte, J.W. Nelson and H.A.
      Moffett.  Proton Induced X-Ray Emission Analysis of Roadway Aerosol
      Time Sequence Filter Samples for Pollution Control Strategy.  In:  IAEA
      Conference Proceedings.  Vienna, March 1976.

109.  Draftz, R.G.  Microscopical Analysis of Aerosols Transported from
      St. Louis.  Presented at:  American Chemical  Society Meeting.  New York,
      NY, April 1976.

110.  Draftz, R.G.  Aircraft Collection and Microscopical Analysis of Ambient
      Aerosols from Urban Atmospheres.  Presented at:  Air Pollution Control
      Assoc. Meeting.  Portland, OR, June 1976.

111.  Draftz, R.G.  Comparison of Elemental and Microscopical Analysis of
      Atmospheric Aerosols.  Presented at:  American Chemical Society Meeting.
      New York City, NY, April 1976.

112.  Draftz, R.G.  Morphology of Airborne Dust in  Maricopa  County, Arizona
      in preparation for presentation at the 1977 AAAS Symposium on Denver
      Dust.  Denver, CO, February 1977.

113.  Farmer, W.M. and J.O. Hornkohl.  Environmental Aerosol Measurements
      Using an Airborne Particle Morphokinetometer.  EPA-600/3-76-087, U.S.
      Environmental Protection Agency, RTP, NC, 1976.

114.  Gillani, N.V. and R.B. Husar.  Analytical-Numerical Model for Mesoscale
      Transport, Transformation and Removal of Air  Pollutants.  In:  Proc.
      7th Technical Meeting on Air Pollution Modeling and its Applications.
      NATO/CCMS.  Airlie, VA, September 7-10, 1976.

115. • Gillani, N.V. and R.B. Husar.  Mesoscale Model for Pollutant Transport,
      Transformation and Ground Removal.  Preprint:  Third Symp. on Atmospheric
      Turbulence, Diffusion and Air Quality, AMS, Raleigh, NC, October 19-22,
      1976.

116.  Gillani, N.V. and R.B. Husar.  Synoptic Scale Haziness Over Eastern
      U.S. and its Long Range Transport.  Invited Paper:  Proc. 4th National
      Conf. of Fire G Forest Meteorology, SAF/AMS,  St. Louis, MO, November
      1976.

117.  Graf, J., R.H. Snow and R.G. Draftz.  Field Air Sampling Study-Phoenix,
      Arizona.  EPA Ecological Research Series.   (In Press).

•118.  Hardy, K.A., R. Akselsson, J.W. Nelson and J.W. Winchester.  1976.
      Elemental Constituents of Miami Aerosol as Function of Particle Size.
      Environ. Sci. and Tech.  10(2):176-182.

119.  Husar, R.B.   1976.  Therman Analysis of Aerosols.  J. of Thermal
      Analysis.  10(2).

                                    121

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120.  Husar, R.B.   Determination of Ambient H^SO^ and its ammonium salts by
      'in situ'  aerosol thermal analysis.   In:   Proc. Symp.  on Radiation in
      the Atmosphere,  Garmisch-Partenkirchen.   Germany,  August 19-28,  1976.

121.  Husar, R.B.,  N.V. Gillani and J.D.  Husar.   A Study of  Long Range Trans-
      port from Visibility Observations,  Trajectory Analysis and Local Air
      Pollution Monitoring Data.  In:   Proc. 7th Technical Meeting on Air
      Pollution Modeling and its Applications.   NATO/CCMS.  Airlie, VA,
      September 7-10,  1976.

122.  Husar, R.B.,  N.V. Gillani, J.D.  Husar and C.C. Paley.   Large Scale
      Haziness Over Midwestern and Eastern U.S.   Presented at:  Symp.  on
'      Radiation in the Atmosphere, Garmisch-Partenkirchen.  Germany,
      August 19-28, 1976.

123.  Husar, R.B.,  N.V. Gillani, J.D.  Husar, C.C. Paley and  P.N. Turcu.  Long
      Range Transport  of Pollutants Observed Through Visibility Contour Maps,
      Weather Maps and Trajectory Analysis.  Preprint:  Third Symp. on
      Atmospheric Turbulence, Diffusion and Air Quality, AMS.  Raleigh, NC,
      October 19-22, 1976.
                                                                   1
124.  Husar, R.B.,  N.V. Gillani and J.D.  Husar.   Particulate Sulfur Formation
      in Power Plant,  Urban and Regional Plumes.  In:  Proc. Symp. on Aerosol
      Science and Technology, 82nd Nat'l Meeting of AIChE.  Atlantic City, NJ,
      August 30-September 1, 1976.

125.  Husar, R.B.,  J.D. Husar, S.B. Fuller, W.H. White,  J.A. Anderson, W.M,.
      Vaughan and W.E. Wilson.  1976.   Sulfur Budget in Large Plumes:   Pollutant
      Flow Rate Measurements in the St. Louis Region.  Submitted to Science.

126.  Husar, R.B.,  J.D. Husar, N.V. Gillani, S.B. Fuller, W.H. White,  J.A.
      Anderson, W.M. Vaughan and W.E.  Wilson.   Pollutant Flow Rate Measurement
      in Large Plumes:  Sulfur Budget  in Power Plant and Area Source Plumes
      in the St. Louis Region.  In:  Proc. American Chemical Society Meeting
      (Div. of Environmental Chemistry).   New York, NY,  April 1976.

127.  Husar, J.D., R.B. Husar, E.S. Macias, W.E. Wilson, J.L. Durham,  W.K.
      Shepherd and J.A. Anderson.  1976.   Particulate Sulfur Analysis:
      Application to High Time Resolution Aircraft, Sampling in Plumes.  Atmos.
      Environ.  10:591.

128.  Husar, J.D., E.S. Macias and R.B. Husar.  High Sensitivity Flame Photo-
      metric Particulate Sulfur Analysis.  In:  Proc. American Chemical
      Society Meeting  (Div. of Environmental Chemistry).  New York, NY,
      April 1976.

129.  Husar, R.B., E.S. Macias and W.P. Dannevik.  Measurement of Dispersion
      with a Fast Response Aerosol Detector.  Preprint:  Third Symp. on
      Atmospheric Turbulence, Diffusion and Air Quality, AMS.  Raleigh, NC,
      October 19-22,. 1976.

130.  Husar, R.B., D.E. Patterson, C.C. Paley and N.V. Gillani.  Ozone in Hazy
      Air Masses.  Presented at:  Internationl Conference on Photochemical
      Oxidant and its  Control.   (EPA)  Raleigh, NC, September 12-17, 1976.
                                     122

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131.  Husar, R.B., D.E. Patterson, W.H. White, D.L. Blumenthal and T.B. Smith.
      1976.  Three-Dimensional Distribution of Air Pollutants in the Los Angeles
      Basin:  Average vertical profiles at Hawthorne, El Monte, Ontario and
      Riverside.  Submitted to:  J. Applied Meteor.

132.  Husar, R.B. and W.H. White.  1976.  On the Color of the Los Angeles
      Smog.  Atmos. Environ.  10(3):199-204.

133.  Johansson, T.B., R.E. Van Grieken and J.W. Winchester.  1976.  Elemental
      Abundance Variation with Particle Size-in North Florida Aerosols.  J.
      of Geophysical Research.  81(6):1039-1046.
                            •

134.  Judeikis, H.S. and T.B. Stewart.  1976.  Laboratory Measurement of SO,,
      Deposition Velocities in Selected Building Materials and Soils.  Aero-
      space report No. ATR-76(7498)-l.

135.  Judeikis, H.S. and T.B. Stewart.  1976.  Laboratory Measurement of
      Heterogeneous Interactions of S0_.  Submitted to:  Atmos. Environ.

136.  Judeikis, H.S. and T.B. Stewart.  1976.  Lab Measurement of S02 Deposition
      Velocities on Selected Building Materials and Solids.  Atmos. Environ.
      10:769.

137.  Kaufman, H.C., K.R. Akselsson and W.J. Courtney.  1976.  A Computer
      Program for PIXE Spectrum Resolution of Aerosols.  Advances in X-Ray
      Analysis.  19:355-366.

138.' Lamb, B.K. and F.H. Shair.  1976.  A Limit Model for Determining the
      Impact of Rural Power Plant Emissions Relative to Urban Emissions Upon
      Urban Air Quality:  Part 1.  Model Description and Consideration of
      Long-term Impacts.  Atmos. Environ.   (In Press).

139.  Lin, M.J. and J.H. Lunsford.  1976.  Electron Paramagnetic Resonance
      Evidence for the Formation of S-0~ on Magnesium Oxide.  J. Phys. Chem.
      80:635-639.

140.  Lin, M.J. and J.H. Lunsford.  1976.  An EPR Study of H_S ~ on Magnesium
      Oxide.  J. Phys. Chem.  80:2015-2018.

141.  Macias, E.S.  1976.  Atmospheric Aerosol Sulfur and Mass Concentration.
      St. Louis, MO, August and September 1975.  (In Press).

142.  Macias, E.S., R.A. Fletcher, J.D. Husar and R.B. Husar.  1976.  Particu-
      late Sulfur Emission Rate from a Simulated Freeway.  In:  The General
      Motors/EPA Sulfate Dispersion Experiment.  EPA-600/3-76-035, U.S.
      Environmental Protection Agency, RTP, NC, 1976.  145 pp.

143.  Macias, E.S., R. Fletcher, J.D. Husar and R.B. Husar.  Particulate
      Sulfur Emission Rate from a Simulated Freeway.  In:  Proc. of Div.
      of Environmental Chemistry, American Chemical Society.  San Francisco,
      CA, August 29-September 3, 1976.

144.  Macias, E.S. and R.B. Husar.  1976.  Atmospheric Particulate Mass
      Measurement with "Two MASS" Beta Attenuation Mass Monitor.  Environ.
      Sci. and Tech.  10:904.


                                    123

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145.  Macias, E.S. and R.B.  Husar.   A Review of Atmospheric Particulate Mass
      Measurement via the Beta Attenuation Technique.   In:   Proc.  of the
      Symposium on Fine Particles.   Minneapolis, MN, May 28-30,  1975.

146.  Macias, E.S. and R.B.'Husar.   1975.   High Resolution  on-Line Aerosol
      Mass Measurement by the Beta  Attenuation Technique.   In:   Proc.  of the
      Second International Conference on Nuclear Methods in Environmental
      Research, Vogt, J.R. (ed.)  U.S.  ERDA, Columbia,  MO.

147.  McSweeney, A.  A Diffraction  Technique to Measure Size Distribution
      of Large Airborne Particles.   EPA-600/3-76-073,  U.S.  Environmental
      Protection Agency, RTP, NC, 1976.

148.  Meinert, D.L. and J.W. Winchester.  1976.  Chemical Relationships in
      the North Atlantic Marine Aerosol.  Submitted to:  J. Geophysical
      Research.

149.  Miller, D.F.  Smog Chamber  Studies of Photochemical Aerosol-Precursor
      Relationships.  EPA-600/3-76-080, U.S Environmental Protection Agency,
      RTP, NC, 1976.

150.  Nelson, J.W., B. Jensen, G.G. Desaedeleer, K.R.  Akselsson and J.W.
      Winchester.  1976.  Automatic Time Sequence Filter Sampling of Aerosols
      for Rapid Multi-Element Analysis by Proton-Induced X-Ray  Emission.
      Advances in X-Ray Analysis.   19:415-425.

151.  Orsini, C.Q., H.C. Kaufmann,  K.R. Akselsson, J.W. Winchester and J.W.
      Nelson.  Variation of Elemental Composition with Particle Size in the
      St. Louis Aerosol.  Presented at:  The International  Conference on
      Particle Induced X-Ray Emission and its Analytical Applications.  Lund,
      Sweden, August 23-26,  1976.

152.  Pilotte, J.O., J.W. Nelson  and J.W.  Winchester.   Application of,
      Multi-Station Time Sequence Aerosol Sampling and Proton Induced X-Ray
      Emission Analysis Techniques  to the St. Louis Regional Air Pollution
      Study for Investigating Sulfur-Trace Metal Relationships.   In:  Proceedings
      of ERDA Symposium on X- and Gamma-Ray Sources and Applications.   Ann
      Arbor, MI, May 19-21,  1976.

153.  Rasmussen, R.A.  1976.  Surface Ozone Observations in Rural and Remote
      Areas.  J. of Occupational  Medicine.  18(5):346-349.

154.  Rasmussen, R.A., R.B.  Chatfield and W.M. Holdren.  Transport of Hydro-
      carbon and Oxidant Chemistries Observed at a Rural Mid-West Site.
      Submitted for publication in:  Proc. of Symp. on the  Non-Urban Tropospheric
      Condition.  Miami Beach, FL,  November 10-12, 1976.

155.  Rasmussen, R.A., E. Robinson  and R. Chatfield.   An Assessment of the
      Lower Tropospheric Continental Ozone Budget.  Submitted for publication
      in:  Proc. Int. Conf. on Photochemical Oxidant Pollution and Its
      Control.  Section on Causes of Urban, Suburban and Non-Urban Oxidant
      Pollution.  Raleigh, NC, September 12-17, 1976.

156.  Richards, J.R., D.L. Fox and  R.C. Reist.  1976.   The  Influence of
      Molecular Complexes on the Photo-Oxidation of Sulfur Dioxide.  Atmos.
      Environ.  10:211-217.

                                     I? A

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157.   Roberts, P.T. and S.K. Friedlander.   1976.   Photochemical Aerosol
      Formation SCU, 1-Heptene,  and NO  in Ambient Air.  Environ.  Sci.  and
      Tech.   10(6):573-580.           X

158.   Roberts, P.T. and S.K. Friedlander'.   1976.   Analysis of Sulfur in
      Deposited Aerosol Particles by Vaporization and Flame Photometric
      Detection.  Atmos. Environ.  10:403-408.

159.   Schwartz, W.E., G.D. Mendenhall, P.W. Jones, C.J. Riggle, A.P. Graffeo
      and D.F. Miller.  Chemical Characterization of Model Aerosols.
      EPA-600/3-76-085, U.S. Environmental Protection Agency, RTP, NC,  1976.

160.   Schwartz, W.E., P.W. Jones, C.J. Riggle,  D.F. Miller and W.E. Wilson.
      1976.   Organic Characterization of Cyclohexene/NO  Aerosol.   Environ.
      Sci. and Tech.  (In Press).

161.   Sheline, J., R. Akselsson and J.W. Winchester.  Trace Element Similarity
      Groups in North Florida Spanish Moss:  Evidence for Direct Up Take of
      Aerosol Particles.  J. of Geophysical Research.  81(6):1047-1050.

162.   Van Grieken, R.E., T.B. Johansson, K.R. Akselsson, J.W. Winchester,
      J.W. Nelson and K.R. Chapman.  1976.  Geophysical Applicability of
      Aerosol Size Distribution Measurements Using Cascade Impactors and
      Proton Induced X-Ray Emission.  Atmos. Environ.  10:571-576.

163.   Waggoner, A.P., A.H. Vanderpol, R.J. Charlson, T.V. Larson,  L. Granat
      and C. Tragardh.  1976.  Sulfate as a Cause of Tropospheric Haze.
      Nature.  261:120-122.

164.   Weiss, R.E., A.P. Waggoner, R.J. Charlson and N.C. Ahlquist.  Sulfate
      Aerosol, It's Geographic Extent.  1976.  Science.  (In Press).

165.   Wesely, M.L., B.B. Hicks, W.P. Dannevik,  S.,Frisella and R.B. Husar.
      1976.   An Eddy-Correlation Measurement of Particulate Deposition from
      the Atmosphere.  Submitted to:  Atmos. Environ.

166.   Whitby, K.T., B. Cantrell, R.B. Husar, N.V. Gillani, J.A. Anderson,
      D.L. Blumenthal, W.E. Wilson, Jr., Ibid;  W.E. Wilson, Jr., R.J. Charlson,
      R.B. Husar, K.T. Whitby and D.L. Blumenthal.  Paper No. 76-30-06.
      69th Annual Meeting of Air Pollution Control Assoc.  Portland, OR.

167.   Whitby, K.T., B.C. Cantrell, R.B. Husar,  N.V. Gillani, J.A.  Anderson,
      D.L. Blumenthal and W.E. Wilson.  Aerosol Formation in a Coal Fired
      Power Plant Plume.  In:  Proc. American Chemical Society Meeting -(Div.
      of Environmental Chemistry).  New York, NY, April 1976.

168.   White, W.H., J.A. Anderson, D.L. Blumenthal, R.B. Husar, N.V. Gillani,
      S.B. Fuller, K.T. Whitby and W.E. Wilson.  Formation of Ozone and
      Light-Scattering Aerosols in the St. Louis Urban Plume.  In:  Proc.
      American Chemical Society Meeting, (Div.  of Environmental Chemistry).
      New York, NY, April 1976.
                                     125

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169.  White, W.H., J.A.  Anderson,  D.L.  Blumenthal,  R.B.  Husar,  N.V. Gillani,
      S.B. Fuller and W.E. Wilson.  1976.   Formation and Transport of Secondary
      Air Pollutants:  Ozone and Aerosols  in the St. Louis Urban Plume.   <
      Science.  194(4261):187-189.

170.  White, W.H..and R.B. Husar.   1976.   A Lagrangian Model of the Pasadena
      Smog Aerosol.  J.  Air Poll.  Control  Assoc.  26(l):32-35.

171.  White, W.H. and R.B. Husar.   1976.   Comments  on Chu & Seinfeld paper -
      "Formulation and Initial Application of a Dynamic Model for Urban
      Aerosols."  Atmos. Environ.   10:85.

172.  Wilson, W.E., R.J. Charlson, R.B. Husar, K.T. Whitby and D. Blumenthal.
      Sulfates in the Atmosphere.   In:   Proc. 69th  Annual Meeting of Air
    - Pollution Control Ass'n.  Protland,  OR, June  27-July 1, 1976.

173.  Wilson, W.E., R.B. Husar, K.T. Whitby, D.B. Kittelson and W.H. White.
      Chemical Reactions in Power  Plant Plumes.  In:  Proc. American Chemical
      Society Meeting, (Div. of Environmental Chemistry).  New York, NY,
      April 1976.

174.  Winchester, J.W.  Assessing  Air Pollution Particulate Fallout Potential
      for Water Pollution in Lake  Michigan.  In:  Proceedings of the Second
      Federal Conference on the Great Lakes.  Interagency Committee on
      Marine Science and Engineering of the Federal Council for Science and
      Technology.  August 17, 1976.

175.  Winchester, J.W.  Sulfur and Trace Metal Relationships in Non-urban
      and Marine Aerosols Studied  Using Proton Induced X-Ray Emissions.
      Presented at:  International Conference on Particle Induced X-Ray
      Emission and its Analytical  Applications.  Lund, Sweden,  August 23-26,,
      1976.                                          .              .       .

176.  Winchester, J.W. and J.W. Nelson. Non-urban Sulfur Aerosol Studies.
      Technical Progress Report December 1975-August 1976.  EPA Grant No.
      R803887, U.S. Environmental  Protection Agency, RTF, NC.  (Contract
      J.W. Winchester for reprints.).
                                    126

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                              APPENDIX C

          PUBLICATIONS,  PRESENTATIONS, AND THESIS LISTING INDEX


 1.   Adams,  F.                98

 2.   Ahlquist,  N.C.           10, 11, 20, 21, 22, 27, 59, 60,  164

 3.   Aksellsson,  R.           54, 72, 76, 97, 107, 118, 137,  150, 151,  161,  162

 4.   Anderson.  J.A.           26, 55, 63, 125, 126, 127, 166,  167, 168,  169

 5.   Baker.  M.B.              40, 53

 6.   Barsic, N.              14

 7.   Berg, W.W.              97

 8.   Bhardwaja. O.S.          27

 9.   Blumenthal,  D.L.         26, 55, 63, 73, 131, 166, 167,  168, 169,  172

10.   Boueres, L.C.S.          98

11.   Brlcard. J.              58

12.   Brock,  J.R.              2, 3, 8, 28, 29, 43, 56, 57, 58, 99, 100,  101,
                              102, 103, 104

13.   Cahill, T.A.             98

14.   Cantrell,  B.             166, 167

15.   Carsey, F.D.             92

16.   Cahpman. K.R.            35, 54, 68, 162

17.   Charlson,  R.J.           4, 6, 7, 9, 10, 11, 20, 21, 22,  27, 31, 40, 42,
                              46, 53, 59, 60, 92, 163, 164,  166,  172

18.   Chatfield, R.B.          154, 155

19.   Courtney.  W.J.           137

20-   Covert. D.S.             9, 10, 60, 92

21.   Crow, L.W.              30

22.   Cunningham,  P.T.         105

23.   Dannevik.  W.P.           106, 129, 165

24.   Davidson,  C.J.           74
                                 127

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25.    DeBower,  K.              103

26.    Desaedeleer.  G.G.        75, 76, 97, 107, 108, 150

27.    Draftz.  R.G.             77, 109, 110, 111, 112, 117

28.    Durham,  J.L.             78, 127

29.    Ellestad, T.G.           78

30.    Ensor,  D.S.              1, 4, 11, 46

31.    Farmer,  U.M.             113

32.    Fletcher, R.A.           142, 143

33.    Forler.  S.H.             7

34.    Fox,  D.L.               79, 156

35.    Frank.  R.               31, 42

36.    Friedlander.  S.K.        5, 17, 32, 34, 61, 74, 80, 82, 157, 158

37.    Friscella. S.            106, 165

38.    Fuller,  S.B.             125, 136, 168, 169

39.    Gartrell. G.             80

40.    Gemma,  J.L.              44

41.    Graf, J.                 117

42.    Graffeo.  A.P.            159

43.    Granat,  L.              106, 163

44.    Grosjean. D.             61, 82

45.    Gillani.  N.V.            81, 94, 114, 115, 116, 121, 122, 123, 124, 130,
                              166, 167, 168, 169

46.    Hardy,  K.A.              76, 97, 118

47.    Harrison, H.             12

48.    Hedgpeth. H.             33, 62

49.    Heintzenberg,  J.         46

50.    Heisler,  S.L.            34

51.    Herbert.  J.              12
                                  128

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52.    Hering.  S.V.             74

53.    Hicks.  B.B.              165

54.    Hidy.  G.M.               17

55.    Holdren. W.M.            154

56.    Hornkohl.  J.O.           113

57.    Husar,  J.D.              84, 121, 122, 123, 124, 125,  126,  127,  128,
                              142, 143

58.    Husar.  R.B.              11, 13, 14, 20, 23, 24, 34, 63,  81,  83, 84,
                              85, 94, 106, 114, 115, 116, 119,  120, 121,
                              122, 123

59.    Jensen,  B.               64, 150

60.    Johansson,  T.B.          35, 36, 51, 54, 65, 66, 68, 71,  72,  86, 93,
                              133, 162

61.    Johnson, P.P.            16, 41

62.    Johnson, S.A.            105

63.    Jones,  P.M.              37, 45, 159, 160

64.    Joseph,  P.M.             45

65.    Judeikis,  H.S.           15, 33, 38, 39, 62, 70, 134,  135,  136

66.    Kaufman, H.C.            54, 72, 137, 151

67.    Kinzer.  G.W.             25

68.    Kittelson.  D.B.          173

69.    Kuhlman, M.R.            79

70.    Lamb,  B.K.               138

71.    Larson,  T.V.             163

72.    Lawsen,  D.R.             98

73.    Levy.  A.                44, 45

74-    Lin. M.J.                16, 87, 139, 140

75.    Lin, C.                  40

76.    Lunsford,  J.H.           16, 18, 19, 41, 50, 67, 69, 87,  139, 140
                                  129

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 77.    Liu.  B.Y.H.              11, 14, 20, 23, 24
 78.    Macias.  E.S.             127, 128, 129, 141, 142, 143,  144,  145,  146
 79.    Madelaine, G.            58
 80.    Marlow,  N.               56, 57
 81.    McJilton. C.E.           31, 42
 82.    McSweeney, A.            147
 83.    Meinert, D.L.            54, 72, 89, 148
 84.    Mendenhall. G.D.         159
 85.    Mlddleton, P.B.          43, 104
 86.    Miller.  P.P.             44, 45, 149, 159, 160
 87.    Miller.  M.S.             17
 88.    Moffett, H.A.            108
 89.    Mueller, P.K.            9
 90.    Nelson.  J.W.             35, 36, 51, 54, 64, 68, 72, 76, 86, 88,  89, 90,
                               91, 97, 98, 108, 118, 150, 151, 152, 162,  176
 91.    Odom.  L.A.               93
 92.    Orsini,  C.Q.             54, 72, 98, 151
 93.    Paley, C.C.              122, 123, 130
 94.    Patterson, D.E.          130, 131
 95.    Pilat, M.J.              4
 96.    Pillotte, J.O.           108, 152
 97.    Porch. W.M.              4, 46, 59
 98.    Pourprix, M.             58
 99.    Rao,  K.V.                69
100.    Rasmussen, R.A.          153, 154, 155
101.    Reist, P.C.              79, 156
102.    Richards. J.R.           156
103.    Rlggle.  C.J.             45, 159, 160
                                  130

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104.    Roberts,  P.T.            157, 158
105.    Robinson,  E.             155
106.    Russell.  P.A.            47
107.    Ruud,  C.O.               47
108.    Schoonheydt,  R.A.        18, 19
109.    Schwartz.  N.E.           25, 44, 45, 159, 160
110.    Sem,  G.J.                26, 55
111.    Shair, F.H.              138
112.    Sheline,  J.              161
113.    Shepherd,  U.K.           127
114.    Shu,  VI.R.                85
115.    Sickles.  J.E.            79
116.    Siegel,  S.               15, 33, 38, 39, 62
117.    Smith. T.B.              131
118.    Snow, R.H.               117
119.    Sperling,  R.             94
120.    Spicer,  C.W.             45
121.    Stewart.  T.B.            33, 48, 49, 62, 70, 134, 135, 136
122.    Stubits.  P.K.            84
123.    Suck, S.                 103
124.    Taarit,  B.Y.             50
125.    Thielke,  J.F.            20
126.    Tokiwa.  Y.               9
127.    Tragardh,  C.             163
128.    Turcu, P.N.              123
129.    Vanderpol, A.H.          60, 92, 163
130.    Vanderwood.  T.B.         97
                                   131

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131.    Van  Grieken, R.E.        35, 36,  51,  54, 65, 66, 68, 71, 72, 86, 93,
                               133, 162

132.    Vaughan. W.M.            94, 125, 126

133.    Waggoner, A.P.           1, 6, 12,  21,  22, 27, 52, 53, 59, 60, 92,
                               163, 164

134.    Weiss.  R.E.              164

135.    Wesely. M.L.             165

136.    Whitby, K.T.             11, 14,  20,  23, 24, 78, 166, 167, 168, 172,  173

137.    White,  U.H.              73, 125, 126,  131, 132, 168, 129, 170, 171,  173

138.    Willeke, K.              78

139.    Williams. I.             68

140.    Wilson. W.E.             25, 63,  78,  125, 126, 127, 160, 166, 168, 169,
                               172, 173

141.    Winchester, J.W.         35, 36,  51,  54, 65, 66, 68, 71, 72, 75, 76,  86, 93,
                               95, 96,  97,  98, 107, 108, 118, 133, 148, 150,
                               151, 152,  161, 162, 174, 175, 176

142.    Winter, J.W.             20

143.    Uu,  M.S.                 29

144.    Zeigler, C.S.            7
                                  132

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                                   TECHNICAL REPORT DATA
                            (Please read Instructions on the reverse before completing)
1. REPORT NO.
  EPA-600/3-77-080
                                                           3. RECIPIENT'S ACCESSION>NO.
4. TITLE ANDSUBTITLE
  AEROSOL RESEARCH  BRANCH, ANNUAL REPORT FY1976/76A
             5. REPORT DATE
                  August  1977
                                                           6. PERFORMING ORGANIZATION CODE
7 AUTHOR(S)
                                                           8. PERFORMING ORGANIZATION REPORT NO.
  W.E. Wilson  and C.  Danskin, editors
9. PERFORMING ORGANIZATION NAME AND ADDRESS
  Environmental  Sciences Research Laboratory - RTF, NC
  Office of  Research and Development
  U.S. Environmental Protection Agency
  Research  Triangle Park, NC  27711
             1O. PROGRAM ELEMENT NO.
                1AA603,  1AD712,  1AA601
             11. CONTRACT/GRANT NO.
 12. SPONSORING AGENCY NAME AND ADDRESS
  Environmental  Sciences Research Laboratory - RTP, NC
  Office of Research and Development
  U.S. Environmental Protection Agency
  Research Triangle Park, NC  27711	
             13. TYPE OF REPORT AND PERIOD COVERED
             	Final	
             14. SPONSORING AGENCY CODE
                   EPA/600/09
 15.SUPPLEMENTARY NOTES/v complementary report,  EPA-600/7-77-076, describes  research
           activities funded by the Energy/Environment program.
 16. ABSTRACT

       The  research program of the Aerosol Research Branch  includes research grants and
  contracts at  institutions in many  parts of the United States,  in addition to an
  intramural program.  The purpose of  these projects is to  study the chemical and
  physical  properties of aerosols, identify the mechanisms  of  aerosol formation and
  removal,  and  conduct experiments to  measure these rates.

       The  results of the research are being used (1) to  establish the contribution of
  the various sources to the ambient atmospheric aerosol  loading,  (2) to characterize
  urban, natural,  and primary and secondary aerosols, (3) to develop quantitative
  descriptions  of  the generation and removal rates associated  with each major aerosol
  source and sink, (4) to quantify the effects of aerosol on atmospheric chemical
  reactions, and (5) as a scientific basis for recommending regulatory actions
  concerned with air quality improvements.

        The research  projects  funded  under EPA's base program are described.
17.
                                KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
                                              b.lDENTIFIERS/OPEN ENDED TERMS  C. COSATI Field/Group
   *Air pollution
   *Aerosols
   ^Research projects
                             13B
                             07D
18. DISTRIBUTION STATEMENT
        RELEASE TO PUBLIC
                                              19. SECURITY CLASS (ThisReport!
                                                 UNCLASSIFIED
                           21. NO. OF PAGES
                                143
20. SECURITY CLASS (Thispage)
   UNCLASSIFIED
                                                                         22. PRICE
EPA Form 2220-1 (9-73)
                                            133

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