r/EPA
United States
Environmental Protection
Agency
Environmental Sciences Research
Laboratory
Research Triangle Park NC 27711
EPA 600 3-79-018
February 1979
Research and Development
Hydrocarbons in
Houston Air
lPA/600/3-79/018
r r
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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 thepu^jjc thfl?ugh the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/3-79-018
February 1979
HYDROCARBONS IN HOUSTON AIR
by
William A. Lonneman
George R. Namie
Joseph J. Bufalini
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
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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.
11
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ABSTRACT
Ambient air samples were collected in Houston downtown and industrial
areas to determine hydrocarbon composition and concentrations. Twenty-one
sampler were collected on three days of sampling: September 1, 1973, and
January 30 and April 2, 1974. The results of the detailed hydrocarbon
analyses of these samples are presented and suggest that both vehicular and
industrial sources of hydrocarbons are important. Some of these samples
were collected during periods of extremely stagnated meteorological condi-
tions. It was observed that although the total nonmethane hydrocarbons
were high, they did not exceed 10 ppmC. Measurements of nitrogen oxides
were made for some of these samples. These samples suggested that the
NMHC/NOX ratio in the Houston area was not atypical, usually ranging from
10/1 to 20/1.
This report covers a period from September 1973 to April 1974 and work
was completed as of June 1977,
111
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CONTENTS
Abstract ill
Figures VI
Tables VI
Acknowledgement vii
1. Introduction 1
2. Conclusions 3
3. Recommendations 4
4. Experimental procedures 5
5. Results and discussion 6
References 18
Appendices
A. Detailed hydrocarbon results 19
B. Meteorological evaluation of the general area 30
v
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FIGURES
Number Page
1 Geographic location of the grab samples collection
sites 8
2 Ozone profiles at the Texas CAMS//1 for the days grab
samples were collected in the Houston areas
TABLES
1 Houston Sampling Sites
2 Sum of Paraffins, Olefins, and Aromatics (ppbC) for Air
Samples Collected on September 11, 1973
3- Sum of Paraffins, Olefins, and Aromatics (ppbC) for Air
Samples Collected on January 30, 1974 14
4 Sum of Paraffins, Olefins, and Aromatics (ppbC) for Air 17
Samples Collected on April 2, 1974
vi
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ACKNOWLEDGEMENTS
The assistance and cooperation of the Texas Air Control Board is grate-
fully acknowledged. Particular appreciation is extended to Dr. Richard
Flannery for the collection of the January 30, 1974, grab samples and for the
many useful discussions concerning the general Houston area.
VII
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SECTION I
INTRODUCTION
Early in 1973 a task force consisting of several scientists from the
State of Texas Air Control Board (TACB) visited the U.S. Environmental
Protection Agency (EPA at Research Triangle Park, North Carolina) to discuss
the hydrocarbon (HC) and oxidant problems of the Houston area. In general,
their concern was the proposed use of transportation control strategy to
control HC emissions and ultimately photochemical ozone (0 ). It was the
TACB contention that this strategy would be ineffective for the Houston area
since industrial sources of hydrocarbons were more abundant than automotive
sources. Total non-methane hydrocarbons (NMHC) exceeding 10 ppmC were ex-
pected at many ground level sites throughout the industrial area. It was
suggested that the Houston atmosphere was atypical in that HC/NO ratios
X
there were much higher than in other cities and that these high ratios would
result in higher urban 0~ concentrations in Houston. It was also conjectured
that due to the high paraffin nature of the ambient HC mix, 0- lifetimes may
be longer. The data base to support these contentions was at that time sparse
and unreliable (1).
The EPA Environmental Sciences Research Laboratory (ESRL; at that time,
Chemistry and Physics Laboratory) was funding a contract with Washington State
University (WSU) for the measurement of HC composition and concentration,
along with corresponding 0 concentration, at five urban sites. Houston was
selected as one of the urban sites, and a study was commenced during the month
of October 1973. An interim report on the WSU study is available (2).
Prior to and on two occasions after the WSU study, grab samples of Houston
ambient air were collected in Tedlar bags and analyzed by the ESRL Mobile
Laboratory. Twenty-one samples were collected on the three sampling days:
September 11, 1973, January 30, 1974, and April 2, 1974. This report
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describes the results of these grab samples studies.
Also included in this report is a meteorological analysis of Houston
and the surrounding area on collection days, since meteorological conditions
affect both photochemical and dispersion characteristics of ambient air.
It would be virtually impossible to relate observed 0_ concentrations to the
NMHC found in this short, three-day sample collection program. Consequently,
the meteorological evaluation was limited to: (1) the dispersion character-
istics of the ambient air and (2) the relationship of mixing characteristics to
observed HC concentration levels.
Since these initial air sampling programs, two additional studies were
performed in the Houston area that are pertinent to the discussion in this
report. The first study consisted of a detailed one-month field sampling
program funded by EPA and conducted by WSU in July 1976 (3). The second
study was a report by Whitehead and Sievers (4), again in 1976, of high NMHC
measurements, average 8.7 ppm, observed in Jones State Forest 40 miles north
of Houston. The latter authors reported that natural HC sources in the
Houston area may be sufficient to produce 0 concentrations which exceed the
Federal 80 ppb 0~ standard. In response to this report, Seila (5) undertook
a bag sampling program on January 4-6, 1978, at sites similar to those used
by Whitehead and Sievers. Seila's results suggest HC levels at least 20
times lower than those reported by Whitehead and Sievers. The HC composition
for the most part resembled that of diluted urban air. Natural HC in these
samples consisted predominately of alpha-pinene at concentrations less than
10 ppbC.
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SECTION 2
CONCLUSIONS
These studies demonstrated that the high NMHC levels (>10 ppmC) suggested
for the Houston industrial areas were not observed. Also, industrial HC
emissions do not necessarily dominate the total NMHC, and a considerable portion
of these hydrocarbons are of vehicular origin. Finally, the HC/NO levels,
x
.although high, are not atypical when compared to other urban areas.
The results of a 3-day study cannot be termed as conclusive; however,
these results are in general agreement with the WSU measurements (2,3).
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SECTION 3
RECOMMENDATIONS
This study represented an initial effort by EPA to measure HC composition
and concentrations in the general Houston area. Since 1973 and 1974,
additional studies have been conducted in the Houston area to assess the
air quality for several pollutants including the hydrocarbons. Future EPA
programs will commence in the Houston area to test air quality simulation
models. An intricate part of this study will be an area-wide NMHC assess-
ment.
The general area of Houston represents a wide diversity of industrial
and vehicular sources. Both accountable and fugitive HC emissions are
expected to be enormous. In order to invoke viable HC control strategy, a
reliable emission inventory of all these sources is needed. Ambient air
samples for hydrocarbons representing combined emissions from these sources
will provide valid emission inventories. Therefore, studies of detailed
NMHC composition and concentration are important and should continue.
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SECTION 4
EXPERIMENTAL PROCEDURES
The gas chromatography procedure and cryogenic concentration system for
the analysis of grab samples in 1973 and 1974 are reported elsewhere (6,7).
Twenty-liter, two-mil, Tedlar P.V.F. (DuPont, Wilmington, Delaware) bags were
filled to half-capacity with a metal bellows pump (Metal Bellows, Sharon,
Massachusetts). The sample collection period ranged from 5 to 10 minutes.
The sampling time and general collection site for each sample are given in
Table I. The bags were shipped via air freight to the ESRL Mobile Laboratory
for detailed HC analysis. The sample bags were partially inflated to preserve
them during air freight shipment; however, some bags were lost in the aircraft
baggage compartments that were not adequately pressurized.
If the sample bags were received within 24 hours of collection, as in the
case of the September 11, 1973, study, NO and NO measurements were made with
a Bendix Model 8101 NO chemiluminescent analyzer. The NO and N09 compositions
X Z
were expected to change with time due to thermal oxidation of NO to NO-. The
NO value (NO + N0?), however, even after a 24-hour storage period, should be
X t-
representative of on-site ambient NO levels. The bag samples collected on
X
January 30 and April 2, 1974, were stored for 48 to 190 hours before analysis;
therefore, the NO analysis was considered unrepresentative due to N00 removal
X £.
by the bag surfaces.
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SECTION 5
RESULTS AND DISCUSSION
Sampling sites for each bag sample collected for the three studies are
shown in Figure 1. A more detailed description of sample site and sample
time are given in Table 1. As shown in the figure the vicinity chos-en for
most sampling was the ship channel area of Houston, since this is the
general location of the industrial complex. It is from this area of Houston
that maximum industrial HC emissions were expected. Since the three sampling
days are separated by months and are characterized by different meteorological
conditions, each day's results will be discussed independently.
September 11, 1973
The September 11 sampling initiated the effort to obtain information
concerning HC pollutant composition of the Houston atmosphere. These samples
were collected prior to the first WSU study (2). The results of the detailed
HC analyses for the bag samples are given in Table A-l. In this study nine
grab samples were collected. Samples H03, H04, H06, H07, and H08 were col-
lected in the vicinity of industrial activity to determine HC composition and
concentration due to these industrial sources. Sample H09 was collected on
the eastern Texas gulf coast to estimate background HC composition and con-
centration coming across the gulf. Sample HOI was collected somewhat north
of downtown Houston but should be typical of the urban HC composition. Samples
H02 and H05 were collected in the Washburn and Baytown tunnels to determine
vehicular HC composition. Using acetylene (C_H.) as a normalizing compound
and assuming that automotive sources are entirely responsible for ambient,
C~H_, ratios of individual HC and HC sums were determined for these tunnel
samples. These ratios were used to estimate the percentage of vehicular
emissions in the other samples. Since non-automotive C9H~ sources have been
identified for the Houston industrial areas, carbon monoxide (CO) measure-
ments were also used to determine vehicular factors. Results for the sum (Z)
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TABLE 1. HOUSTON SAMPLING SITES
Code
HOI
H02
H03
H04
H05
H06
H07
H08
H09
HI 2
HI 3
H14
HI 5
HI 6
H17
HIS
H21
H22
H23
H24
H25
Sampling time (C.D.T.)
1550
1445
1217
1130
1155
1310
1340
1400
1455
0650
0720
0805
0845
1020
1115
1205
0730
0800
0815
0920
0940
Location
Reagan Road at Euclid Road
Baytown Tunnel
Pasadena (TACB site)
Jacinto City (TACB site)
Washburn Tunnel
Industrial Drive
Channel View
Decker Road
Red Bluff
Minden and Dabney Streets
Jacinto City (TACB site)
Pasadena (TACB site)
Queens Road & Revere
Jacinto City (TACB site)
Pasadena site (TACB site)
Downtown Houston
Jacinto City
Industrial Drive
Jacinto Port Road
Deer Park
Pasadena
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of paraffins (P), olefins (0), and aromatics (A) ratios to both C?H and
CO are given in Table 2. Although our two tunnel samples are insufficient
to calculate a vehicular emission factor, McMurry et al. (9) in a 1975
Houston study, determined a vehicular emission factor of 8.09 + .43 for
the C2~C5 HC. This value compares well with our C^-C, EC factor of 8.32 +
0.62, determined for tunnel samples H02 and H05.
As shown in Table 2, the use of either CO or C_H. as vehicular emission
factors gave similar results of vehicular composition for samples HOI, H03,
and H04. For example, both CO and C-H. factors indicate the vehicular
fraction of sample HOI is approximately 40%. However, this is not the case
for samples H06, H07, H08, and H09. In these samples the factor ascribes
a considerably larger NMHC percentage to vehicular sources than does the
C«H factor. This factor disparity is probably traceable to background CO
CHANNELVIEW DRIVE
• TUNNEL SAMPLES
Figure 1. Geographic location of the grab sample collection sites.
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TABLE 2. SEPTEMBER 11, 1973, MEASUREMENTS
S A M P L
Component
*
ZP
*
zo
*
ZA
ZP/C2H2
ZO/C2H2
ZA/C2H2
ZP/CO
ZO/CO
ZA/CO
%P
%0
%A
NO f
N°2"
NO
X
HOI
691.5
269.5
569.8
17.4
6.4
13.6
0.36
0.13
0.28
46.5
17.1
36.4
70.0
25.0
95.0
H02
5101.
2164.
2552.
9.
4.
5.
0.
0.
0.
51.
22.
26.
1480.
320.
1800.
4
4
3
9
2
0
15
16
08
8
0
2
0
0
0
H03
244.7
71.6
135.5
27.8
8.1
15.4
0.38
0.11
0.21
54.2
16.8
30.0
15.0
20.0
35.0
H04
205.0
61.4
102.2
9.9
3.0
4.9
0.19
0.06
0.10
55.6
16.9
27.5
30.0
20.0
50.0
H05
6492
2985
3006
7
3
3
0
0
0
52
24
24
1580
380
1960
E
.1
.5
.6
.8
.6
.6
.14
.06
.06
.0
.0
.0
.0
.0
.0
H06
184.2
42.8
119.0
42.8
10.0
27.7
0.53
0.12
0.34
53.2
12.4
34.4
15.0
15.0
30.0
H07
355.3
28.4
93.6
177.6
14.2
46.8
1.62
0.13
0.43
74.4
5.9
19.6
10.0
10.0
20.0
H08
321.3
67.7
141.2
84.6
17.8
37.2
0.95
0.20
0.42
60.6
12.8
26.6
10.0
10.0
20.0
H09
89.3
15.8
92.5
52.5
9.3
54.5
0.41
0.07
0.42
45.1
8.0
46.9
5.0
15.0
20.0
*
ppbC
t
ppb
-------
and not other combustion sources. The CO concentrations for samples H06, H07,
H08, and H09, range from 0.22 to 0.35 ppm. At these levels the contribution
of natural background CO (approximately 0.10 ppm) is significant. If this
background value is removed from the observed CO concentration and the cal-
culation repeated, better agreement of vehicular percentage is obtained for
both factors.
In some areas of Houston, industrial sources of both C~H and CO may be
important. In these cases other vehicular factors such as an unreactive
paraffinic or aromatic compound could be utilized. Two such examples are
benzene and n-hexane. Kopczynski et al. (8) utilized indicator compounds
other than C^H' to determine common sources for several HC components.
Although not specifically stated, these indicator compounds served a dual role
of accounting for vehicular and non-vehicular sources, such as gasoline spillage
and evaporative emissions.
The meteorological conditions on September 11 are described in detail
in Appendix B; these conditions are usually associated with rather high
inversion layers and good vertical mixing. Consequently, low concentrations
of ground level HC were expected. Indeed low levels of total NMHC were
observed for all samples, with the exception of the urban sample HOI; which
contained 1567 ppbC. Total NMHC concentrations at the industrial sites
ranged from 346. to 530. ppbC. These concentrations are much lower than
those suggested by TACB personnel and only two to three times greater than
the background HC levels of 197 ppbC observed at the east gulf coast site
(sample H09).
Nitrogen oxide measurements were made for the sample bags, since the
storage times of these samples were >12 hrs. These results are reported in
Table 2. Previous laboratory storage studies of NO -air mixtures have shown
X
reasonable storage of NO for up to 24 hr with ^20-30% conversion of NO to N09
X ^
due to thermal oxidation. When storage times were increased, NO levels
X
decreased, a probable result of N0~ loss to the bag surface. These previous
NO storage studies suggest the NO measurements in the Houston air sample
X X
bags are reasonably accurate; however, the inaccurate NO to N0« ratios are
expected. As a point of interest, the photochemical 0 potential of
the ambient air in Houston was calculated using the standard ozone isopleths
10
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utilized for the EKMA model (10). Assuming that the morning levels of non-
methane hydrocarbon and nitrogen oxides were similar to those given in Table
2 i.e., NMHC to range from 350-1500 ppbC and NO to range from 20 to 95 ppb,
2C
the afternoon ozone maximum was calculated to exceed 80 ppb. Figure 2
represents 0 levels observed at the TACB CAMS #1 station on September 11, 1973;
such levels are lower than the 80-ppb level calculated by the isopleth method.
The differences are probably due to differences in meteorological conditions
between isopleth model and real atmosphere, and to imperfections of the isopleth
method.
Although these HC/NO ratios may be somewhat high, they are not extra-
X
ordinarily different than those found in other cities.
Vehicular hydrocarbons at the non-tunnel sites can be estimated by
comparing HC/C-H^ or EC/CO ratios from non-tunnel samples to those ratios
obtained in tunnel samples (Table 2). These comparisons are valid only if
vehicular sources are the only significant source of C-H- CO and if the tunnel
auto emissions do not differ significantly from those in the city.
Significant non-vehicular sources of paraffins, olefins, and aromatics
were observed at most sampling sites. At some of these locations, vehicular
sources can account for only 10-15% of the total NMHC. In contrast, at site
HOI, representing the urban plume, ^50% of the total HC can be attributed
to vehicular sources. These values of vehicular emission at the various sites
are in general agreement with those reported in the Westberg et al. Houston
study (3). Closely inspecting the individual components of the samples col-
lected at the industrial sites and contrasting their ratios to C H with
corresponding tunnel sample ratios suggest that the non-vehicular paraffins
compounds consist principally of the C, to C, variety. Similar inspection
of the olefin components indicates non-vehicular sources of the C to C, com-
pounds. These sample carbon components are consistent with components of
petroleum refinery type emissions. Non-vehicular sources of toluene, m-xylene
and 1,2,4 tri-methyl benzene are suggested by a similar treatment of the
aromatic compounds. Industrial sources of these aromatic compounds are cer-
tainly possible; however, it is also possible that these compounds could be
halogenated or oxygenated compounds having retention times similar to the
identified aromatic compounds.
11
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As alluded to earlier, non-vehicular sources of gasoline spillage and
gasoline evaporative emissions contribute significantly to the total NMHC
burden. A series of indicator compounds could possibly be utilized to
estimate the contribution of these sources, if the general HC composition
of the gasoline utilized during this sample period were known. Since this
information was not available, these calculations were not performed.
These few samples cannot characterize a typical atmospheric composition
for the Houston area, since meterological conditions are expected to cause
both HC compositional and concentration variations. However, from these
few samples, four conclusions can be made:
1. HC concentrations at these industrial sites do not routinely exceed 1
ppmC and depend greatly on meteorological conditions.
2. A significant percentage of the NMHC at these industrial sites resulted
from non-vehicular sources.
110
LU
0200 0400 0600 0800 1000 1200 1400 1600 1800 2000 2200 2400
TIME, hrs
Figure 2. Ozone profiles at the Texas CAMS #1 (1262 Mae Drive) for the days grab samples
were collected in the Houston area.
12
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:#
4." ! StfMfil^Be/NC** ratiosr are not atypical compared to otiliftr ^tirbatf area&'fend
significant non-vehicular HC sources were observed, significant non-
vehicular NO sources are suggested.
January 30, 1974
The purpose of the bag sample study conducted on January 30, 1974,
was to determine the effect of stable meteorological conditions on HC com-
position and concentration. Tedlar bags were sent to the TACB for sample
collection during stagnant meteorological conditions. Sample site and
identification are given in Figure 1 and Table 1. Detailed results of the
g.c. analysis of the collected samples are givne in Table A-2.
HC pollutant levels during this study appear approximately an order of
magnitude higher than those measured on September 11, 1973. This difference
is evident when the NMHC sum or the CO concentrations on the two days are
compared. Furthermore, many of the individual hydrocarbons showed corresponding
increases, suggesting similar pollution sources on both September 11 and
January 30.
A January 30 meteorological analysis revealed a high pressure system
centered directly over the Houston area. Since land-based high pressure
systems generally occur north of Houston, the NMHC levels observed in these
samples are assumed maximum or near maximum for the Houston area. The reported
wind direction during sample collection was from WSW to WNW. The wind speed
was reported < 2 mph during the entire sample collection period; however,
decreased concentrations in samples H16, H17, and H18 suggest a wind speed
increase associated with a general breakup of the inversion conditions later
in the morning. An Air Stagnation Advisory was issued at 11:00 a.m. by the
TACB. A more detailed meteorological analysis is given in Appendix B.
Shown in Table 3 are ratios of sums of paraffins, olefins, and aromatics
to both C2H2 and CO. No tunnel samples were collected during this study;
therefore, in order to estimate vehicular emission contribution, the tunnel
ratios determined during the September 11, 1973, study were used. Estimates
13
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of percentage vehicular emissions are also given in Table 3. Applying
these runnel ratios to the January 30 data demonstrates that vehicular
sources can account for 50-100% of the NMHC observed at these sample sites.
This percentage range is considerably higher than percentages measured on
September 11 and suggests that during stagnation conditions vehicular sources
contribute more significantly to NMHC emissions. This NMHC percentage
variation does not represent diminished industrial emissions during stagnant
conditions, but it does suggest that ambient HC composition can change under
different meteorological conditions. If we assume that the remaining non-
vehicular NMHC fraction is of industrial origin, concentrations exceeding
2.00 ppmC can be attributed to these sources. However, spilled and evaporated
gasoline sources must also be included in the non-vehicular fraction.
TABLE 3. JANUARY 30, 1974, MEASUREMENTS
Component H12
HI 3
SAMPLE
H14 H15 H16
HI 7
HIS
*
ZP
*
zo
*
ZP/C H
2 2
ZO/C H
ZA/C2H2
ZP/CO
zo/co
ZA/CO
%P
%0
%A
3819.2
493.6
802.0
29.9
3.9
6.3
0.74
0.10
0.16
74.6
9.7
15.7
2613.
519.
772.
9.
1.
2.
0.
0.
0.
66.
13.
19.
9
8
5
5
9
8
35
07
10
9
4
7
3945.2
781.0
1176.0
24.0
4.8
7.2
0.46
0.09
0.14
66.7
13.3
20.0
6746
991
1215
19
2
3
0
0
0
75
11
13
.7
.4
.0
.4
.9
.5
.40
.06
.07
.2
.2
.6
1752
297
799
20
3
9
0
0
0
61
10
28
.7
.7
.6
.9
.5
.5
.43
.07
.20
.7
.3
.0
2112
372
750
23
4
8
0
0
0
65
11
23
.1
.2
.8
.7
.2
.4
.56
.10
.20
.3
.6
.1
2220.8
275.9
815.0
14.6
1.8
5.4
0.42
0.05
0.15
67.0
8.3
24.7
ppbC
14
-------
,
*'"*•- jrasaxSSiia site used f^oV the collection of H03. Likewise, samples HIS and H16
were collected at the San Jacinto site used for the collection of sample H04.
In general, the compositional results of the two studies are in agreement. In
both studies, large non-vehicular emissions were observed at the Pasadena
site, and lower non-vehicular emissions were observed at the San Jacinto site.
Comparison between the Table 3 (January 30) sums of paraffins, olefins,
and aromatics ratios to C?H and CO and the Table 2 (September 11) tunnel ratios
shows additional sources of paraffins in all but one Table 3 sample (H13).
Additional sources of aromatic compounds and to a lesser extent olefinic
compound, are observed in just a few January 30 samples. This is contrary to
the industrial site samples of September 11, where significant contribution of
both olefinic and aromatic compounds were observed. In both the September 11
and January 30 samples the principal non-vehicular paraffin compounds con-
sisted of the C.-C, components.
4 o
These January 30 samples contain extremely high concentrations of methane,
ethane, and propane, observed especially in the earlier morning samples (H12,
H13, H14, and H15); A natural gas origin possibly the numerous Houston area
oil fields is the probable source. Also the abundant use of natural gas, the
principal fuel source for area electric power generation, likely gives rise
to large fugitive natural gas loss. Since these bags were stored for periods
up to 190 hours before analysis, nitrogen oxide measurements were not made.
Shown in Figure 2 are ambient 0_ values at the TACB CAMS Number 1 station
for January 30. Ozone was observed for a period of ~ 10 hr to exceed the
NAQS standard, while maximum 0 approached 110 ppb. Although this value is
high, it is lower than that expected for the stagnated January 30 conditions.
The somewhat lower temperature and decreased sunlight during January were no
doubt responsible for reduced 0 formation.
Four observations can be made from the study of January 30, 1974.
1. Even under the extreme inversion conditions of that day, total NMHC did
not exceed 10 ppmC in these areas of Houston.
15
-------
2. Industrial HC sources were significant but did not dominate the total
NMHC emissions.
3. The HC composition of samples collected at identical sites during the
September 11, 1973, and January 30, 1974, studies were similar, although
the different meteorological inversion conditions were different.
4. Since a high pressure system was centered over the Houston area on Jan-
uary 30, the NMHC levels measured in that day can be considered to be
near the maximum levels expected to occur in Houston.
April 2, 1974
Samples collected on April 2, 1974, were included in this report, even
though these samples were collected near vinyl chloride and polyvinyl chloride
plants to determine ambient levels of vinyl chloride. These sampling sites,
shown in Figure 1, were in the general collection site areas for the September
11 and January 30 studies. The HC analysis results are given in Tables 4
and A-3. The total NMHC levels for these samples were comparable to those
levels observed in the September 11 study, as shown in a comparison of
Table A-l with Table A-3 results. A general summary of the meteorological
conditions on April 2 is given in Appendix B.
16
-------
TABLE 4. APRIL 2, 1974, MEASUREMENTS
SAMPLE
*
EP
*
EO
EA
EP/C2H2
EO/C H
2 2
EA/C9H
2 2
EP/CO
EO/CO
EA/CO
%P
%0
%A
H21
469.8
351.2
256.1
17.0
12.7
9.3
0.20
0.15
0.11
43.6
32.6
23.6
H22
546.9
147.7
244.4
71.0
19.2
31.7
1.09
0.30
0.49
58.2
15.8
26.0
H23
1105.7
112.7
327.9
197.4
20.1
58.5
1.78
0.18
0.53
71.5
7.3
21.2
H24
106.4
44.1
83.1
31.3
13.0
24.4
0.19
0.08
0.15
45.6
18.9
35.5
H25
125.8
26.2
59.4
8.7
1.8
4.1
0.34
0.07
0.16
59.5
12.4
28.0
ppbC
17
-------
REFERENCES
1. Johnson, D.J., H. Tomomatsu and R.R. Wallis, Ambient Air Quality Study
Gadena Park, Texas, Texas State Department of Health, Austin, Texas,
1973, 67 pp.
2. Westberg, H., and R.A. Rasmussen, Monthly Technical Report, October
1-31, 1973, Contract Number 68-02-1232, November 20, 1973.
3. Westberg, H., K.Allwine, and E. Robinson. Measurement of Light Hydro-
carbons and Oxidant Transport-Houston Area Study 1976, EPA 600/3-78-062,
U.S. Environmental Protection Agency, Research Triangle Park, NC, 1978,
240 pp.
4. Whitehead, L., and R.K. Sievers. Background Hydrocarbon Levels in East
Texas. In: Proceedings of American Institute of Chemical Engineers 83rd
National Meeting, Houston, Texas, March, 1977.
5. Seila, R.A. Ambient Air Hydrocarbon Concentrations at W.G. Jones State
Forest, Montgomery County, Texas, EPA report, to be published.
6. Lonneman, W.A., S.K. Kopczynski, P.E. Darley, and F.D. Sutterfield. Hydro-
carbon Composition in Urban Aceas, Environ. Sci. Technol., 8_: 220, 1974.
7. Lonneman, W.A. Ozone and Hydrocarbon Measurements in Recent Oxidant
Transport Studies. In: Int. Conf. on Photochemical Oxidant Pollution
and Its Control Proceedings, EPA 600/3-77-OOla, U.S. Environmental
Protection Agency, Research Triangle Park, NC, 1977, p. 211.
8. Kopczynski, S.L., W.A. Lonneman, T. Winfield, and R. Seila. Gaseous
Pollutants in St. Louis and Other Cities. J. Air Poll. Control Assoc.,
25: 251, 1975.
9. McMurry, J.R., R. Planner, L.H. Fowler, and D. J. Johnson. Ambient
Sampling for Stationary and Mobile Source Hydrocarbons in Houston, Texas.
Proceedings of Annual Air Pollution Control Association Meeting, Boston,
Massachusetts, June, 1975, 14 pp.
10. Uses, Limitation and Technical Basis of Procedures For Quantifying
Relationships Between Photochemical Oxidants and Precursors, EPA-450/2-
77-021a, Research Triangle Park, North Carolina, February 1977.
18
-------
APPENDIX A
DETAILED HYDROCARBON RESULTS
Included in Appendix A are detailed HC species results obtained from
air samples collected in the Houston area on September 11, 1973, January
30, 1974, and April 2, 1974. Individual component concentrations for the
NMHC are given in parts per billion carbon (ppbC). The concentrations
of methane and carbon monoxide in air are in parts per million concentration
(ppm).
19
-------
TABLE A-l. DETAILED HC ANALYSIS (ppbC) OF AIR
SAMPLES COLLECTED IN HOUSTON ON SEPTEMBER 11, 1973
Compound
Ethane
Ethylene
Propane
Acetylene
Isobutane
n-Butane
Propylene
Isobutylene
trans-2-Butene
cis-2-Butene
1,3-Butadiene
Isopentane
n-Pentane
1-Pentene
2 Methyl-1-Butene
trans-2-Pentene
cis-2-Pentene
2 Methyl-2-Butene
Acetaldehyde
Cyclopentane
Isoprene
2-Methylpentane
3-Methylpentane
4 Methyl-2-Pentene
n-Hexane
1-Hexene
Unknown
trans- 3-Hexene
2,4 Dimethyl pentane
Methylcyclopentane
cis-2-Hexene
Unknown
Propionaldehyde
Acetone
3,3 Dimethylpentane
Cyclohexane
2 Methylhexane
2,3 Dimethylpentane
3 Methylhexane
1 c 3 Dimecyclopentane
2,2,4 Trimethylpentane
1 t 3 Dimecyclopentane
n-Heptane
HOI
35.1
174.7
28.0
41.9
41.5
111.3
22.5
20.8
4.1
2.5
4.1
117.8
58.5
4.8
7.1
9.4
11.4
7.9
52.3
21.8
0.0
30.4
0.0
0.0
7.2
12.7
0.0
8.0
15.3
22.5
22.9
0.0
32.0
16.2
H02
115.3
958.0
26.5
513.0
102.0
604.5
405.8
233.2
54.8
24.0
121.1
995.9
435.2
30.9
48.4
88.3
48.9
69.1
603.6
275.7
25.1
230.4
18.7
41.9
132.0
296.2
34.2
12.4
23.2
174.2
99.2
182.9
53.2
293.6
138.9
20
SAMP
H03
24.8
30.8
22.7
8.8
21.4
38.0
7.3
8.4
4.0
1.0
2.8
42.1
20.8
1.7
1.8
2.9
7.8
3.1
21.7
7.3
0.0
14.3
0.0
0.0
5.0
10.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
L E
H04
21.7
24.5
19.0
20.7
11.4
29.2
9.6
11.6
4.0
0.0
4.0
33.5
20.0
1.3
1.1
2.2
1.3
1.8
19.8
8.5
0.0
8.5
,0.0
0.0
2.1
4.7
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
H05
182.3
1362.7
82.6
829.7
259.6
729.8
512.2
412.9
67.3
30.0
133.2
1227.0
567.6
38.4
53.8
137.5
63.5
91.9
653.4
287.9
27.5
273.4
28.8
73.5
153.0
286.8
25.8
13.0
134.3
211.2
191.2
231.8
75.5
416.3
100.3
(continued)
-------
Compound
TABLE A-l. (Continued)
Sample
H06 H07 H08
H09
Ethane
Ethylene
Propane
Acetylene
Isobutane
n-Butane
Propylene
Isobutylene
trans-2-Butene
cis-2-Butene
1,3-Butadiene
Isopentane
n-Pentane
1-Pentene
2 Methyl-1-Butene
trans-2-Pentene
cis-2-Pentene
2 Methyl-2-Butene
Acetaldehyde
Cyclopentane
Isoprene
2-Methylpentane
3-Methylpentane
4 Methyl-2-Pentene
n-Hexane
1-Hexene
Unknown
trans-3-Hexene
2 , 4 Dimethyl pentane
Methylcyclopentane
cis-2-Hexene
Unknown
Propionaldehyde
Acetone
3 , 3 Dimethylpentane
Cyclohexane
2 Methylhexane
2,3 Dimethylpentane
3 Methylhexane
1 c 3 Dimecyclopentane
2,2,4 Trimethylpentane
1 t 3 Dimecyclopentane
n-Heptane
Methylcyclohexane
25.0
10.1
33.7
4.3
24.8
33.3
13.5
8.4
2.0
2.0
2.0
14.3
7.9
1.2
1.3
1.1
0.0
1.2
4.8
3.8
0.0
6.4
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
13.8
13.9
18.8
2.0
16.8
52.6
3.5
1.1
1.5
0.0
0.0
78.2
76.7
0.0
0.0
1.7
6.7
0.0
29.3
12.1
0.0
22.2
0.0
2.5
2.1
6.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
17.0
16.8
19.9
3.8
40.4
50.7
4.2
14.7
6.8
6.5
0.0
57.4
44.1
3.2
3.5
4.2
4.0
3.8
25.2
12.6
0.0
9.4
0.0
0.0
8.0
24.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
16.2
6.3
13.0
1.7
5.8
11.5
0.1
4.5
0.0
0.0
0.0
9.4
7.7
0.0
0.0
0.0
4.0
0.0
4.9
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
21
(continued)
-------
Compound
Methylcyclohexane
T oluene
n-Nonane
Ethylbenzene
p-Xylene
m-Xylene
o-Xylene
Isopropylbenzene
n-Decane
n-Propylbenzene
p-Ethyltoluene
m-Ethyl toluene
1,3,5 Trimethylbenzene
°-Ethyltoluene
1,2,4 Trimethylbenzene
Unknovm
1,2,3 Trimethylbenzene
n-Butylbenzene +
P-Diethylbenzene
m-Die thylbenz ene
Unknown
Sum of Other Unknowns
on MBMA Column
Sum of Other Unknowns
on DBMfc Column
Methane A
Carbon monoxide
TABLE
HOI
16.8
132.0
.19.9
19.8
20.0
86.1
75.1
13.5
20.4
3.8
15.5
15.5
5.7
182.9
36.6
0.0
0.0
0.0
0.0
2.01
2.04
A-l. (Continued)
SAMPLE
H02 H03
73.5
887.8
69.2
124.3
101.4
420.5
162*6-
103.6
46.6
213.6
66.1
61.0
221.6
18.3
51.2
60.0
108.0
27.6
2.05
34.0
0.0
35.6
6.4
6.7
5.0
13.0
8.8
7.3
10.1
4.5
10.9
0.0
9.6
31.8
2.3
0.0
0.0
0.0
1.77
0.65
H04
0.0
44.2
7.8
5.3
5.3
21.0
8.4
8.7
1.3
5.8
2.6
1.5
6.8
10.1
0.0
0.0
0.0
0.0
1.75
1.05
H05
100.3
1014.0
74.2
154.2
150.0
521.7
205.7
98.0
61.1
268.8
77.5
78.5
245.5
17.5
54.2
51.2
97.0
27.4
2.83
46.8
Methane and CO concentrations are expressed as parts per million (PPM)
22
-------
Compound
Toluene
n-Nonane
Ethylbenzene
p-Xylene
m-Xylene
Unknown
o-Xylene
Isopropylbenzene
n-Decane
n-Propylbenzene
p-Ethyl toluene
m-Ethyltoluene
1,3,5 Trimethylbenzene
°-Ethyltoluene
1,2,4 Trimethylbenzene
Unknown
1,2,3 Trimethylbenzene
n-Butylbenzene +
p -Diethylbenzene
m-D ie thy Ib enz ene
Unknown
Sum of Other Unknowns
on MBMA Column
Sum of Other Unknowns
on DBMA Column
Methane . ^
Carbon monoxide
TABLE A-l.
H06
39.5
4.7
2.5
4.0
10.6
8.2
4.7
10.4
0.0
1.0
2.2
2.2
7.8
15.1
0.0
36.3
0.0
0.0
1.76
0.35
(continued)
SAMP
H07
14.2
1.4
3.1
3.2
9.4
7.4
0.0
11.9
0.0
1.9
0.1
0.1
7.1
10.9
47.1
0.0
0.0
0.0
1.62
0.22
L E
H08
35.8
5.7
6.6
6.0
8.1
7.9
7.6
6.9
2.8
11.5
5.4
4.7
45.6
0.0
0.0
0.0
0.0
0.0
1.75
0.34
H09
39.3
13.8
3.9
4.6
7.5
8.9
0.0
7.0
0.0
6.0
3.8
3.9
11.0
0.0
Q.Q
0.0
0.0
0.0
1.53
0.22
The concentrations of these compounds are parts per million (PPM)
23
-------
*
TABLE A-2. DETAILED HC ANALYSIS (ppbC) OF AIR
SAMPLES COLLECTED IN HOUSTON ON JANUARY 30, 1974
Compound
Ethane
Ethylene
Propane
Acetylene
Isobutane
n-Butane
Propylene
Isobutylene
trans-2-Butene
cis-2-Butene
1,3-Butadiene
Isopentane
n-Pentane
1-Pentene
2 Methyl-1-Butene
trans-2-Pentene
cis-2-Pentene
2 Methyl-2-Butene
Acetaldehyde
Cyclopentane
Isoprene
2-Methylpentane
3-Methylpentane
4 Methyl-2-Pentene
n-Hexane
1-Hexene
Unknown
trans- 3-Hexene
2,4 Dimethyl pentane
Methylcyclopentane
cis-2-Hexene
Unknown
Propionaldehyde
Acetone
3,3 Dimethylpentane
Cyclohexane
2 Methylhexane
2,3 Dimethylpentane
3 Methylhexane
1 c 3 Dimecyclopentane
2,2,4 Trimethylpentane
1 t 3 Dimecyclopentane
n-Heptane
Methylcyclohexane
H12
283.7
143.0
247.7
127.6
158.7
827.2
88.3
47.1
18.8
18.0
7.1
641.5
277.4
14.5
24.3
45.3
17.1
39.8
53.1
169.1
112.2
13.1
101.2
5.5
13.2
11.7
36.7
79.6
18.4
19.7
10.7
19.6
45.6
48.4
71.0
26.6
118,9
56.2
71.1
260.0
H13
197.9
201.9
160.5
277.8
128.8
624.8
81.1
66.5
16.9
14.4
20.1
416.4
197.2
9.5
16.1
32.5
9.4
29.8
38.8
114.0
75.8
7.0
74.3
7.7
7.5
7.0
21.6
56.3
9.1
11.7
5.1
18.9
43.6
44.6
56.6
14.0
72.7
29.9
34.9
131.8
Sample
H14
280.8
262.8
285.6
164.1
171.9
707.4
109.3
65.0
24.7
18.0
49.3
675.4
281.1
20.8
36.3
59.5
23.1
52.6
58.1
192.8
136.2
21.3
153.3
24.2
22.0
14.1
49.3
114.7
24.9
7.9
3.7
37.1
68.1
72.1
85.0
20.7
146.8
34.9
81.3
90.0
H15
751.8
331.9
592.4
347.8
305.7
1604.1
153.9
107.0
32.2
32.0
23.0
1076.0
453.2
28.9
47.6
80.0
29.6
67.8
81.5
267.7
173.4
11.2
176.8
27.6
24.2
18.7
55.3
142.3
24.6
16. 11
8.9
42.7
76.2
74.4
119.3
28.4
157.9
66.4
60.4
229.8
H16
188.1
331.9
214.7
83.9
80.4
233.1
37.2
29.8
7.5
4.7
11.8
192.8
103.0
7.0
8.7
23.3
7.0
8.5
19.9
76.7
47.3
2.3
81.3
0.0
6.5
0.0
25.0
41.0
0.0
0,0
0.0
15.7
28.1
26.3
41.0
15.9
51.9
41.3
23.8
154.0
24 (continued)
-------
Compound
TABLE A-2. (Continued)
Sample
H17 HIS
Ethane ,
Ethylene
Propane
Acetylene
Isobutane
n-Butane
Propylene
Isobutylene
trans-2-Butene
cis-2-Butene
1,3-Butadiene
Isopentane
n-Pentane
1-Pentene
2 Methyl-1-Butene
trans-2-Pentene
cis-2-Pentene
2 Methyl-2-Butene
Acetaldehyde
Cyclopentane
Isoprene
2-Methylpentane
3-Methylpentane
4 Methyl-2-Pentene
n-Hexane
1-Hexene
Unknown
trans-3-Hexene
2,4 Dimethyl pentane
Methylcyclopentane
c is-2-Hexene
Unknown
Propionaldehyde
Acetone
3 , 3 Dimethylpentane
Cyclohexane
2 Methylhexane
2,3 Dimethylpentane
3 Methylhexane
1 c 3 Dimecyclopentane
2,2,4 Trimethylpentane
1 t 3 Dimecyclopentane
n-Heptane
Methylcyclohexane
142.8
149.9
171.2
89.1
142.9
418.9
45.2
42.7
14.8
13.0
50.6
375.0
151.4
8.0
12.0
37.8
10.0
11.7
28.1
97.5
58.7
0.0
86.9
0.0
5.7
3.2
15.2
55.5
0.0
0.0
0.0
15.6
26.1
20.2
35.2
12.3
39.1
25.1
31.1
81.3
73.6
124.3
45.7
151.8
58.6
236.3
36.4
30.7
6.7
5.5
7.2
268.8
112.8
5.9
9.4
21.7
6.0
8.1
26.8
87.8
59.6
4.4
56.5
4.2
8.7
5.6
22.0
45.2
0.0
0.0
0.0
10.2
38.9
40.9
58.4
17.4
76.1
47.9
32.9
196.8
25
(continued)
-------
Compound
Toluene
n-Nonane
Ethylbenzene
p-Xylene
m-Xylene
o-Xylene
Isopropylbenzene
n-Decane
n-Propylbenzene
p-Ethyltoluene
m-Ethyltoluene
1,3,5 Trimethylbenzene
o -Ethyltoluene
1,2,4 Trimethylbenzene
Unknown
1,2,3 Trimethylbenzene
n-Butylbenzene +
p -Diethylbenzene
m-Diethylbenzene
Unknown
Sum of Other Unknowns
on MBMA Column
Sum of Other Unknowns
on DBM^ Column
Methane .
TABLE
H12
230.8
22.1
41.9
32.7
118.4
57.8
13.9
15.8
45.2
51.6
10.0
60.6
94.8
15.4
26.8
7.15
A-2. (Continued)
Sample
H13 H14
219.1
18.1
47.0
28.4
124.6
53.2
6.3
13.1
49.2
46.6
10.0
47.0
79.4
11.7
43.0
4.64
415.0
49.2
54.6
50.0
155.8
74.3
11.0
56.3
18.8
68.4
45.2
19.3
67.8
114.5
17.8
63.5
6.46
H15
371.6
47.2
59.3
44.6
167.1
79.6
23.5
46.4
21.5
85.7
68.9
30.0
80.7
87.7
14.8
80.0
12.1
H16
187.4
11.2
39.4
29.0
101.1
50.8
44.2
33.8
6.5
34.4
50.8
16.0
39.5
124.1
9.4
67.0
4.0
Carbon monoxide 5.13 7.63 8.54 16.7 4.04
*
Methane and CO concentrations are expressed in parts per million (ppm)
t
Ethylene peaks are contaminated by the effluent from the Ethylene-Ozone
Chemiluminescent Instrument
26
-------
Compound
Toluene
n-Nonane
Ethylbenzene
p-Xylene
m-Xylene
o-Xylene
Isopropylbenzene
n-Decane
n-Propylbenzene
p-Ethyltoluene
m-Ethyltoluene
1,3,5 Trimethylbenzene
o -Ethyltoluene
1,2,4 Trimethylbenzene
Unknown
1,2,3 Trimethylbenzene
n-Butylbenzene +
p-Diethylbenzene
m-Diethylbenzene
Unknown
Sum of Other Unknowns
on MBMA Column
Sum of Other Unknowns
on DBM Column
Methane A
Carbon monoxide
TABLE A-2.
Sample
HI 7
223.3
14.9
35.3
27.8
88.8
42.0
28.6
40.8
5.9
21.4
39.3
10.0
28.5
152.8
11.1
36.0
3.50
3.76
(Continued)
H18
196.5
11.1
31.0
24.5
73.8
45.6
45.7
33.6
10.0
34.7
64.8
10.0
41.8
151.6
17.0
68.0
2.43
5.34
Ethylene peaks are contaminated by the effluent from the Ethylene-Ozone
Chemiluminescent Instrument
*
Methane and CO concentrations are expressed in parts per million (ppm).
27
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TABLE A-3. DETAILED HYDROCARBON ANALYSES (ppbC) OF AIR SAMPLES
COLLECTED IN HOUSTON ON APRIL 2, 1974
Compound
Ethane
Ethylene
Propane
Acetylene
Isobutane
n-Butane
Propylene
Isobutylene
trans-2-Butene
cis-2-Butene
1,3-Butadiene
Isopentane
n-Pentane
1-Pentene
2 Methyl-1-Butene
trans-2-Pentene
cis-2-Pentene
2 Methyl-2-Butene
Acetaldehyde
Cyclopentane
Isoprene
2-Methylpentane
3-Methylpentane
4 Methyl-2-Pentene
n-Hexane
1-Hexene
Unknown
trans-3-Hexene
2,4 Dimethyl pentane
Methylcyclopentane
cis-2-Hexene
Unknown
Propionaldehyde
Acetone
3,3 Dimethylpentane
Cyclohexane
2 Methylhexane
2,3 Dimethylpentane
3 Methylhexane
1 c 3 Dimecyclopentane
2,2,4 Trimethylpentane
1 t 3 Dimecyclopentane
n-Heptane
Methylcyclohexane
H21
274.7
105.8
27.6
35.5
53.5
17.5
21.2
4.9
3.1
7.5
80.9
44.7
1.6
2.0
11.8
3.1
3.9
34.9
14.7
0.0
19.5
0.0
3.2
13.2
0.0
0.0
0.0
9.5
6.1
2.3
5.8
6.1
6.7
4.5
S
H22
41.8
78.2
63.9
7.7
39.7
71.1
27.9
21.0
1.8
1.1
1.4
77.4
42.8
1.3
2.1
9.6
1.7
1.6
36.5
24.9
0.0
27.9
0.0
1.1
12.4
0.0
0.0
0.0
20.5
7.8
3.5
10.2
14.7
13,3
15.8
A M P L E
H23
32.7
38.0
71.6
5.6
98.8
147.7
21.2
8.7
3.2
2.6
1.6
347.8
133.9
3.0
3.7
20.9
4.7
4.1
74.3
30.3
1.0
29.3
0.0
6.2
18.5
0.0
0.0
0.0
11.1
10.3
7.0
12.5
28.2
18.7
15.0
H24
22.6
32.7
26.3
3.4
8.4
20.7
3.1
1.5
1.3
0.0
0.0
5.2
9.7
0.5
0.0
4.5
0.5
0.0
5.2
5.1
0.0
3.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
H25
17.4
10.6
21.5
14.4
7.7
31.8
4.2
1.8
0.9
0.2
20.1
10.0
0.5
0.5
5.2
2il
0.0
7.5
3.1
0.0
3.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
(continued)
28
-------
Compound
Toluene
n-Nonane
Ethylbenzene
p-Xylene
m-Xylene
o-Xylene
Isopropylbenzene
+ Styrene
n-Decane
n-Propylbenzene
p-Ethyltoluene
m-Ethyltoluene
1,3,5 Trimethylbenzene
o-Ethyltoluene
1,2,4 Trimethylbenzene
Unknown
1,2,3 Trimethylbenzene
n-Butylbenzene +
p-Diethylbenzene
m-Diethylbenzene
Unknown
Sum of Other Unknowns
on MBMA Column
Sum of Other Unknowns
on DBty Column
Methane *
Carbon monoxide
TABLE A-3.
H21
48.2
2.9
24.5
14.9
64.6
20.3
35.5
19.0
9.4
20.4
6.8
2.6
5.3
4.1
0.6
6.4
2.31
1.04
(Continued)
S A
H22
90.5
6.6
13.0
28.2
36.7
14.6
28.5
11.2
2.7
10.6
4.3
1.0
11.6
4.0
11.1
5.9
2.05
1.50
M P L E
H23
62.4
3.7
5.7
5.9
28.4
46.5
20.3
6.5
1.2
4.6
3.0
0.5
138.5
9.0
10.2
5.5
1.96
0.62
H24
22.2
0.7
5.2
3.3
11.9
3.6
26.8
4.6
0.9
1.6
2.4
0.2
3.7
3.6
17.1
2.8
1.91
0.57
H25
17.0
0.6
3.9
2.9
10.3
3.4
15.5
3.1
0.2
2.3
2.0
1.4
4.0
2.5
4.1
2.3
1.91
0.37
The concentration of these compounds are parts per million (ppm).
Ethylene peaks are contaminated by the effluent from the Ethylene-Ozone
Chemiluminescent Instrument.
29
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APPENDIX B
METEOROLOGICAL EVALUATION OF THE GENERAL AREA
INTRODUCTION
Meteorological parameters affecting the potential for air pollution
episodes in Houston, Texas, were examined for the dates September 11, 1973,
January 30, 1974, and April 2, 1974. These parameters include temperature,
moisture, and wind structure. Synoptic weather patterns were analyzed.
Stagnating high pressure systems were identified and tracks of the systems
were developed. Mixing depths and inversion layers were identified for
each day. Ventilation factors were calculated, and estimates of residence
times were made.
RESULTS AND DISCUSSION
September 11, 1973
Synoptic Description — A low pressure cell formed off the Gulf coast of Texas,
The cell moved inland as the day progressed. Skies over Houston were over-
cast the entire day, and thunderstorms developed by midday. ''Temperatures
remained steady throughout the day (range 25 -27 C). Winds remained from a
north to northeast direction with speeds averaging 10-15 mph, except in the
thunderstorm.
Mixing Depth — The mixing depth is defined as the distance from the ground
to the bottom of the first inversion. For this case the mixing depth is
very large (2000 m) and the atmosphere is considered unstable (encourages
vertical mixing). This situation indicates a good spread of pollutants
vertically. Temperature profiles are found in Figure B-l for the periods of
early morning, noon, and early evening.
Ventilation Factor — The ventilation factor is defined as the product of the
mixing depth and the average wind between the ground and the top of the mixed
layer. The average wind makes up the horizontal transport of air parcels.
30
-------
I 0600
UNSTABLE
20
0
TEMPERATURE (°C)
20
NOON
TOP OF INVERSION
THIN STABLE ~~
LAYER
BASE OF INVERSION
-20
20
TEMPERATURE (°C)
20
I ! 1800
UNSTABLE
0
TEMPERATURE (°C)
20
Figure B-1. Vertical temperature profiles, for Houston, Texas, September 11, 1973
M
-------
For September 11 the average wind from the surface to 2000 m was 12.5 m/s
2
(25 mph), which gives a ventilation factor of 25,000 m /s. For cases of high
potential for pollution episodes the ventilation factor can range from near
2 2
zero (with a surface based inversion) to 6,000 m/s. A value of 25,000 m Is
suggests a small potential for a pollution episode.
Role of Precipitation — The role of precipitation should be taken into account
(1) because of the likely effect of cleansing and (2) because of the difficulty
in calculating mixing depths that fluctuate with varying precipitation
conditions.
Residence Time —The residence time is defined as the number of days air
parcels spend in high pressure systems. Since Houston was under the
influence of a low pressure system, the residence time for September 11 is
very low.
January 30, 1974
Synoptic Description — Houston was under the influence of a very large, cold,
high pressure system located in the Ohio Valley. The track of the system is
shown in Figure B-2. The system made its way from southern Canada, dipped
east of the Rockies, moved over Texas and into the Mississipi and Ohio
Valleys. As the high pressure system showed signs of stagnation, a secondary
high pressure cell developed over central Texas and moved eastward into
northern Florida. Skies remained clear the entire day. Temperatures ranged
from 9 C in early morning to a maximum of 22 C at noon. Winds were very
light (< 3 m/s) and variable.
Mixing Depth — Temperature profiles are found in Figure B-3 for early
morning, noon, and early evening. For the early morning, the mixing
depth was very close to the surface (10 m), indicating very little vertical
mixing. The top of the inversion was located at ~ 100 m. As the day pro-
gressed, the noon time mixing depth was 65 m with the top of the inversion
at ~ 900 m, indicating increased vertical mixing. The early evening mixing
depth reached its peak at 850 m with the top of the inversion at 900 m.
Good vertical mixing is indicated for this time period. Since Houston is
in a stagnating anticyclone, the mixing depth at sunset will quickly decrease
to height similar to that of the early morning.
3:2
-------
Ventilation Factor —- Since the mixing depth and average horizontal wind
speed are very low most of the day, a small ventilation factor is determined.
This small value indicates a ]arge potential for a pollution episode. Table
B-l shows the values of the ventilation factors for the three time periods
examined.
TABLE B-l. HOUSTON, TEXAS, VENTILATION FACTORS FOR JANUARY 30, 1974
Time
0600
1200
1800
Height
(m)
10
65
850
Wind Speed
(m/s)
1.0
1.0
2.0
Height X Wind
(m2/s)
10.0
65.0
1700.0
Speed
JAN 31
0600
0600
JAN 30
0000
HOUSTON
JAN 28
1200 JAN 30
1800
JAN 31
0000
Figure B-2. Tracks of high pressure centers, for the period of Jan. 28-31, 1974.
33
-------
0600
SURFACE BASED INVERSION
TOP OF INVERSION
STABLE LAYER
20
0
TEMPERATURE (°C)
20
STABLE LAYER
I 1
NOON
TOP OF INVERSION
BASE OF INVERSION
20
0
TEMPERATURE (°C)
20
1800
STABLE LAYER
TOP OF INVERSION
BASE OF INVERSION
20 0 20
TEMPERATURE (°C)
Figure B-3. Vertical temperature profile for Houston, Texas, January 30, 1974.
34
-------
Residence Tirae — Houston was under the influence of a stagnating high
pressure system so that an estimate of 3 days for residence time would
not be unreasonable.
1974
On April 2, 1974, Houston was under the influence of a slowly moving,
low pressure cell. A cold front had developed along the cell and moved into
Houston by midday. Heavy showers preceded the front as the cloud layer
thickened. Winds were strong, from the southwest (10 m/s); after the passage
of the front, they shifted to the northwest and remained fairly strong
(8 m/s). Temperatures ranged from 26 C in midday to 17 C by early evening.
Temperature profiles were taken for early morning and early evening.
Both profiles showed the cold front. No early morning surface-^ased
inversion was found. For the early morning, the base of the inversion was
at 800 m with the top of the inversion at 1100 m. The mixing depth was
800 m. The average wind speed in the mixing layer was 5 m/s and the ven-
2
tilation factor 4000 m s (800 m X 5 m/s).
The evening temperature profile showed the same 800 m inversion base,
but a wind speed increase (~ 7.5 m/s) in the layer was noted. The ven-
2
tilation factor then was 6000 m /s. This factor represents the upper
limit for pollution potential, but no pollution problem existed. This is
perhaps due to the role precipitation plays in cleansing the atmosphere
of its pollutants.
35
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/3-79-018
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
HYDROCARBONS IN HOUSTON AIR
S. REPORT DATE
February 1979
6. PERFORMING ORGANIZATION CODE
7 AUTHOR(S)
William A. Lonneman, George Namie, and
Joseph J. Bufalini
8. PERFORMING ORGANIZATION REPORT NO.
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, North Carolina 27711
10. PROGRAM ELEMENT NO.
1AA603A
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, North Carolina 27711
13. TYPE OF REPORT AND PERIOD COVERED
In-house 9/73-4/74
14. SPONSORING AGENCY CODE
EPA/600/09
IS. SUPPLEMENTARY NOTES
16. ABSTRACT
Ambient air samples were collected in Houston downtown and industrial areas
to determine hydrocarbon composition and concentrations. Twenty-one sampler were
collected on three days of sampling: September 1, 1973, and January 30 and
April 2, 1974. The results of the detailed hydrocarbon analyses of these samples
are presented and suggest that both vehicular and industrial sources of hydrocarbons
are important. Some of these samples were collected during periods of extremely
stagnated meteorological conditions. It was observed that although the total
nontnethane hydrocarbons were high, they did not exceed 10 ppmC. Measurements of
nitrogen oxides were made for some of these samples. These samples suggested that
the NMHC/NO ratio in the Houston area was not atypical, usually ranging from
10/1 to 20/1.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
COSATl Field/Group
*Air pollution -
*Hydrocarbons
*Chemical analysis
Houston area
13B
07C
07D
13. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (This Report)
UNCLASSIFIED
21. NO. OF PAGES
44
20 SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
36
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