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PAH source fingerprints for coke ovens, diesel and, gasoline engines, highway tunnels, and wood combustion emissions
Pergamon
Atmospheric
Environment Vol. 29, No. 4, pp. 533-542, 1995 Cowrixht 0 1995 Elsevier Science Ltd Printed in &eat Britain. All rights reserved 1352-2310/95 $9.50 + 0.00
13522310(94)0027M
PAH SOURCE FINGERPRINTS FOR COKE OVENS, DIESEL AND GASOLINE ENGINES, HIGHWAY TUNNELS, AND WOOD COMBUSTION EMISSIONS NASRIN
R. KHALILI,*
PETER A. SCHEFFt
and THOMAS
M. HOLSEN*
*Pritzker Department of Environmental Engineering, Illinois Institute of Technology, Chicago, IL 60616, U.S.A.; tEnvironmenta1 and Occupational Health Sciences, University of Illinois at Chicago, School of Public Health, P.O. Box 6998, M/C 922, Chicago, IL 60680, U.S.A. (First received 10 April 1993 and injnalform
16 July 1994)
Abstract-To evaluate the chemical composition (source fingerprint) of the major sources of polyaromatic hydrocarbons (PAHs) in the Chicago metropolitan area, a study of major PAH sources was conducted during 1990- 1992. In this study, a modified high-volume sampling method (PS-1 sampler) was employed to collect airborne PAHs in both the particulate and gas phases. Hewlett Packard 5890 gas chromatographs equipped with the flame ionization and mass spectrometer detectors (GC/FID and GC/MS) were used to analyze the samples. The sources sampled were: coke ovens, highway vehicles, heavy-duty diesel engines, gasoline engines and wood combustion. Results of this study showed that two and three ring PAHs were responsible for 98,76,92,73 and 80% of the total concentration of measured 20 PAHs for coke ovens, diesel engines, highway tunnels, gasoline engines and wood combustion samples, respectively. Six ring PAHs such as indeno(l,2,3&)pyrene and benzo(ghi)perylene were mostly below the detection limit of this study and only detected in the highway tunnel, diesel and gasoline engine samples. The source fingerprints were obtained by averaging the ratios of individual PAH concentrations to the total concentration of categorical pollutants including: (a) total measured mass of PAHs with retention times between naphthalene and coronene, (b) the mass of the 20 PAHs measured in this study, (c) total VOCs, and (d) total PMlO. Since concentrations of the above categorical pollutants were different for individual samples and different sources, the (chemical composition patterns obtained for each categorical pollutant were different. T’he source fingerprints have been developed for use in chemical mass balance receptor modeling calculations. Key word index: PAH, source fingerprint, chemical mass balance.
INTRODUCTION
Polyaromatic hydrocarbons (PAHs) are formed by incomplete combust.ion or pyrolysis of organic material containing carbon and hydrogen (Jones and Leber, 1980). They are multi-ringed compounds and many are known to be carcinogenic (Lee et al., 1981; Byrne et al., 1982). Interest in the carcinogenic effects of combustion products dades back at least 200 years, when Sir Percival Pott noted an increase in scrotal cancer among chimney sweeps in London. Association of the cancer with a specific chemical contained in combustion products was strengthened in 1933 when the PAH, benzo(a)pyrene, was isolated from chimney soot (Freeman and Cattel, 1990). The continuing interest in PAHs in air is due t,o the results of laboratory studies which have found that many other PAHs are also carcinogenic (Jones and Leber, 1980; Lee et al., 1981). Although numerous researchers have measured PAH concentration:< in ambient air, very few studies link their presence to a specific source. Motor vehicles are thought to be the major source of atmospheric
PAHs in the United States, accounting for 35% of the
yearly total. Aluminum production and forest fires each contribute 17%, followed by residential wood combustion, coke manufacturing, power generation and incineration which emit 12, 11, 6 and 3% of the yearly total, respectively (Benner et al., 1989). To understand the relationship between sources of air pollution and observed air quality, a variety of efforts including development of the chemical mass balance receptor models (CMB) have been made in recent years (Scheff et al., 1984). CMB models use the chemical and physical characteristics of both gases and particles measured at sources and receptors to both identify the presence of and to quantify source contributions to the receptor (Gordon, 1988). This model consists of a least-squares solution to a set of linear equations which expresses each receptor concentration of a chemical species as a linear sum of the product of source composition and total source contributions. Input data to the model include the source composition as the fractional amount of selected species in the emissions from each source category, the receptor concentrations of the selected species and appropriate uncertainty estimates. The CMB models 533
N. R. KHALILI et al.
534
have been applied to organic species (Gordon, 1988; Kenski, 1991). Modeling with organic chemicals, however, is limited due to difficulties associated with analytical methods and the availability of reliable chemical composition data. This paper presents the results of a study conducted to determine the chemical composition of major sources of PAHs in the Chicago metropolitan area. Emissions from coke ovens, vehicles in a highway tunnel, diesel engines, gasoline engines and wood combustion were quantitatively evaluated using an optimized method for sampling and analyzing PAHs present in atmospheric aerosols and gases with a sampling time of 2-4 h (Chang, 1991).
EXPERIMENTAL DESIGN
In general, organic air pollutants can be divided into two phases according to the different sampling techniques: (1) the particulate phase, and (2) the gas phase consisting of semivolatile and volatile compounds with boiling points higher than 100°C (Tuominen et al., 1988). PAHs have a wide range of vapor pressure and a knowledge of the distribution of these compounds between gas and particulate phases is important for the development of a sampling plan (Chuang et al., 1987; Pyysalo et al., 1987; Yamasaki et al., 1982). The sampling equipment used in this study was a semivolatile high-volume sampler model PS-1 (General Metal Works Inc.). The PS-1 sampling train is designed to collect suspended airborne particulate matter on a filter and vapor phase compounds on a backup sorbent. Particles were collected on 11 cm diameter glass micro fiber filters. The gas phase PAHs were collected in a modified cartridge containing XAD-2 resin sandwiched between layers of polyurethane foam (PUF). This system was found to retain 99% of the naphththalene, the most volatile PAH measured in this study, and therefore the compound most likely to break through the sorbent during the 4 h sampling period (Khalili, 1992). The qualitative/quantitative identification of PAHs was performed using a Hewlett Packard 5890 gas chromatograph equipped with an autosampler and a flame ionization detector. To confirm the peak identification, 10% of the samples were also analyzed by a Hewlett Packard 5890 gas chromatograph equipped with a mass spectrometer detector (GC/MS). Where possible, results of this study were compared to the ratios of PAHs to indicator PAHs such as benzo(e)pyrene and benzo(a)pyrene reported in other studies. To determine the source fingerprints, measured concentrations of PAHs for each sample were normalized to the concentrations of categorical pollutants for that sample and source fingerprints were calculated by averaging the mass fractions for individual PAHs from each sample in each source category. Sampling program
A total of 19 samples from selected PAH sources in the Chicago area were collected and analyzed during 1990-1992. Five samples of emissions from urban vehicles were taken in heavily traveled tunnels during evening rush hours (4.OC-7.00 p.m.). The first tunnel sample was taken along the Kennedy Expressway and the other four tunnel samples were taken along Lower Wacker Drive at the intersection with Michigan Avenue in downtown Chicago. Five samples were collected 100 m directly downwind of a coke plant located in southeast Chicago. During sampling, there were no other operating steel making facilities near the coke plant so that the samples collected were not influenced
by other steel making processes. The coke oven samples were all obtained between 5:OOand 1O:OOp.m. Four samples of heavy-duty diesel engine emissions were obtained in a Chicago Transit Authority bus parking garage on the north side of Chicago (public transportation bus stopping facility). Diesel engine emission samples were collected on Friday and Monday mornings between 4.00 and 7.00 a.m. The two samples collected on Friday represent warm-engine emissions and two samples collected on Monday represent cold-start engine emissions. Emissions from gasoline engines were collected from a public parking garage located in downtown Chicago. Three samples that represent warm-engine operation were taken between 6:30 and 900 a.m. Two samples of emissions were collected from fireplaces, burning seasoned oak wood which is the most common type of wood burned in the Chicago area. These samples were collected on the roof of a house directly downwind of the chimney. Selected PAHs
A group of 20 PAHs were selected for analysis. They include a group of suspected carcinogens including benzo (a)pyrene, benzo(b)fluoranthene, and indeno(l,2,3,cd)pyrene. In addition the concentrations of coronene, phenanthrene, anthracene, fluoranthene, pyrene, acenaphthene, triphenylene, cyclopenta(cd)pyrene, and benzo(ghi)perylene were measured. These compounds have been found in the ambient air (Pyysalo et al., 1987), and some of them have been identified as potential tracers of PAH emissions (Ramdahl et al., 1982). Naphthalene, acenaphthylene, benzo(k)fluoranthene, chrysene, (1,2,5,6)-dibenz(ah)anthracene, and fluorene are the remaining compounds on the EPA PAH priority pollutants list and were included in the study of completeness. Benzo(e)pyrene was also included because PAH concentrations are often reported relative to it. The final compound analyzed, retene, has been suggested as a marker for coniferous wood smoke (Ramdahl, 1983). Sample preparation
Source samples were prepared for analysis within 24 h after collection. Preparation included sample extraction, volume reduction (concentration), sample cleanup, final concentration, and GC analysis. The filter and cartridge were Soxhlet extracted together for 24 h with a mixture of acetone:hexane (60:40). The extract was concentrated to 1 ml under purified N, and total extracted organics were fractionated on a silica gel cleanup column (Pyysalo et al., 1987). The selected fraction (PAH group) was collected and concentrated under purified N, gas to 0.2 ml. Treated samples were subsequently analyzed by GC/FID. The qualitative/quantitative identification of PAHs was performed using a Hewlett Packard 5890 gas chromatograph equipped with an autosampler and a flame ionization detector. To confirm the peak identification, 10% of the samples were also analyzed by a Hewlett Packard 5890 gas chromatograph equipped with a mass spectrometer detector (GC/MS). The gas chromatograph was calibrated with certified PAH standards. A master standard solution of 22 PAHs (20 PAHs, and two internal standards) was used in the GC calibration processes. Quantification of individual PAHs in the sample was determined by direct injection of a known concentration of a calibration mixture (master PAH standard) to determine area response per injected mass of each compound. In the GC analysis a 50 m Ultra-2,0.32 mm i.d. column coated with 5% methyl silicon was used with high purity helium \yith a flow rate of 1 mlmin-’ at 29o”C, as a carrier gas. A 3 ~1 sample was injected into the splitless injector at 300°C. The initial oven temperature was 50°C; after injection the oven temperature was rapidly increased to 100°C at a rate of 20”Cmin-‘, 100 to 290°C with a rate of 3°C min- 1 and held for 40 min. The FID detector was
PAH source fingerprints operated at 300°C utihzing pure air and hydrogen gas at a rate of 400 and 30 ml :min- i, respectively. The averaged value of response factors for individual PAHs (RF,) was calculated based on repeated injection of various concentrations of the master PAH standard solution. The retention times (RT,) of individual PAH compounds as well as internal standards for compound identification were also determined in the calibration processes. As a part of the quality control/quality assurance effort (QC/QA), the efficiency of each individual sampling technique and analytical procedure has been independently investigated by the addition of a known amount of internal standards to the master PAH standard solution and field samples. In general, total recovery obtained for individual PAHs in this study ranged from 80 to 95%. A detailed discussion of the recovery efficiencies is presented1 elsewhere (Khalili, 1992). The results of analysis performed on field blanks indicated an insignificant contamination level lower than the GC detection limit (i.e. lower than 0.124 ng, GC detection limit of naphthalene). The detection limit for each PAH was obtained by injecting sequentially dimted standard solutions to the GC. The instrument detection limit increased with increasing molecule weight and ranged from 0.124 to 1.42 ng, for naphthalene and coronene, respectively. PM10 and VOC samples Particulate matter (PMIO) and volatile organic compounds (VOCs) samples were simultaneously collected with each PAH sample. PM 10concentrations were measured with a medium flow (4 cfm) PM10 sampler, fitted with a Teflon filter. Proton induced X-ray emission (PIXE) and neutron activation analyses (NAA) were carried out on the filters for elemental analysis. Volatile organic compounds (VOCs) were also collected in 6 L electropolished stainless steel canisters using a constant massflow controlled bellows pump. Analysis for 57 organics plus total non-methane organic compounds (NMOC) carbon was carried out using a high resolution gas chromatograph (HRGC) fitted with a cryogenic trap and flame ionization and electron capture detectors (FID and ECD) (Wadden et al., 1991).
535 RESULTS AND DISCUSSION
The average concentrations obtained for each PAH in the emissions from the five sources studied are presented in Table 1. The fingerprints for coke ovens, highway tunnels, diesel engines, gasoline engines and wood combustion are presented in Tables 2-7. The concentrations of individual PAHs in the sampled sources in Chicago and those reported by others were normalized to those of benzo(e)pyrene and benzo(a)pyrene to ease the comparison between the results of this study and others (Tables 8 and 9). The calculated mass distributions of PAHs in different sources are shown in Table 10.
Source jingerprints Studies performed during the last decades showed that PAHs have significant variation in their composition for different combustion sources (Gordon and Bryan, 1973; Gordon, 1988; Daisey et al., 1979) and their fingerprints if available can be used in the sources identification models such as CMB receptor models. Reviewing the recent studies indicated that due to the existing differences between selected sampling techniques and/or adopted analytical procedures a great deal of inconsistency exists between reported data for PAH source fingerprints. Up to this date the important problem associated with the application of the chemical mass balance receptor models for organic air pollutants such as PAHs, has been the absence of a reliable source fingerprint. In this study efforts were made to develop the chemical composition (fingerprints) of the major sources of the PAHs in Chicago
Table 1. Average concentration (pg rnm3) of individual PAHs in sampled sources in Chicago
PAHs Naohthalene Acdnaphthyle ne Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Retene Cyclop(cd)pyrene Benz(a)anthracene Chrysene Benzo(b)fluoranthene Benzo(k)fluoranthene Benzo(e)pyrene Benzo(a)pyrene Indeno(l,2,3,cd)pyrene Dibenz(ah)anthracene Benzo(ghi)perylene Coronene
Coke oven 22.4 0.747 0.023 0.502 0.500
0.158 0.0883 0.0563 0.00957 0.00220 0.00759 0.0147 0.00477 0.00801 0.0116 0.00533 0.0011 bd
0.000690 bd
*Warm engine samples. t One measurement. bd: below the detection limit of this study.
Diesel engines* 0.386 0.464 0.566 0.651 0.472 0.251 0.0806 0.0489 0.0558 0.222 0.249 0.143 0.137 0.0977 0.130 0.302 0.250 0.170 0.108 0.025t
Tunnel 8.03 0.445 0.168 0.406 0.300 0.177 0.117 0.193 0.0787 0.100 0.0902
0.0779 0.0436 0.0412 0.0555 0.0626 0.0200 0.0147 0.0170 bd
Gasoline engines 2.46 0.0708 0.0377 0.123 0.0398 0.0388 0.0446 0.0719 0.0437 0.05 14 0.00586 0.0283 0.0330 0.0255 0.122 0.0270 bd bd 0.00918t 0.0145t
Wood combustion 0.402 1.83 0.0515 0.128 0.219 0.350 0.0959 0.100 0.0041 0.0296 0.0187 0.0328 0.0234 0.0446 0.197 0.203 bd bd bd bd
N. R. KHALILI
536
et al.
Table 2. Source composition of coke oven emission Source composition, weight percentage of categorical pollutant PAH
TPAH*
Naphthalene Acenapththylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Retene Cyclop(cd)pyrene Benz(a)anthracene Chrysene Benzo(b)fluoranthene Benzo(k)fluoranthene Benzo(e)pyrene Benzo(a)pyrene Indeno Dibenz(ah)anthracene Benzo(ghi)perylene Coronene
7.01 0.216 0.0122 0.200 0.221 0.0549 0.0425 0.0300 0.00384 0.00125 0.00524 0.00901 0.00242 0.00556 0.00734 0.00323 0.00109 bd 0.0007 bd
Total
7.82
* Source composition lene and coronene. t Source composition $ Source composition 8 Source composition
20PAHt 89.8 2.94 0.149 2.47 2.62 0.690 0.489 0.334 0.0465 0.0145 0.0558 0.0971 0.0278 0.0611 0.0839 0.0358 0.00886 bd 0.00535 bd 100
TVOCsj
TPMlO$
1.49 0.0552 0.00376 0.0459 0.0526 0.0134 0.0101 0.00657 0.00085 0.00047 0.00162 0.00222 0.00047 0.00162 0.00211 0.00081 0.0000 bd 0.00000 bd
22.6 0.763 0.0276 0.529 0.527 0.160 0.0954 0.0624 0.0100 0.00259 0.00935 0.0163 0.00533 0.00935 0.0140 0.00621 0.00134 bd 0.00081 bd
1.69
24.8
normalized to the total PAH mass with retention times between naphthanormalized to the sum of the 20 identified PAHs. normalized to the total emission of volatile organic compounds. normalized to the total emission of PM 10.
Table 3. Source composition of diesel engines Source composition, weight percentage of categorical pollutant PAH
TPAH*
Naphthalene Acenaphthylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Retene Cyclop(cd)pyrene Benz(a)anthracene Chrysene Benzo(b)fluoranthene Benzo(k)fluoranthene Bcnzo(e)pyrene Benzo(a)pyrene Indeno Dibenz(ah)athracene Benzo(ghi)perylene Coronene
0.163 0.0958 0.165 0.133 0.0958 0.0384 0.0158 0.00667 0.0119 0.0206 0.0249 0.0155 0.0143 0.00732 0.0132 0.0195 0.0265 0.00707 0.0112 0.00049
Total
0.886
* Source composition lene and coronene. t Source composition $ Source composition §Source composition
20PAHt 24.5 10.7 13.5 13.2 9.11 4.18 1.46 0.900 1.19 3.07 3.44 1.94 1.58 1.14 1.58 3.12 2.64 1.345 1.17 0.0921 100
TVOCs$
TPMlO$
0.3860 0.0688 0.0820 0.0484 0.0255 0.0143 0.00533 0.00350 0.00417 0.0132 0.0171 0.00948 0.00797 0.00769 0.00852 0.0144 0.0112 0.00777 0.00598 0.00040
1.25 0.217 0.237 0.1466 0.0741 0.0412 0.0148 0.0115 0.0130 0.0389 0.0492 0.0262 0.0192 0.0212 0.0220 0.0359 0.0225 0.0170 0.0135 0.00069
0.741
2.27
normalized to the total PAH mass with retention times between naphthanormalized to the sum of the 20 identified PAHs. normalized to the total emission of volatile organic compounds. normalized to the total emission of PMlO.
PAH source fingerprints
537
Table 4. Source composition of warm diesel engine Source composition, weight percentage of categorical pollutant PAH
TPAH*
20PAHt
TVOCsf:
TPMlO$
Naphthalene Acenaphthlylene AcenaphthLene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Retene Cyclop(cd)pyrene Benz(a)anthracene Chrysene Benzo(b)fluoranthene Benzo(k)fluoranthene Benzo(e)pyrene Benzo(a)pyrene Indeno Dibenz(ah)~anthracene Benzo(ghi)perylene Coronene
0.0387 0.0490 0.0501 0.0689 0.0495 0.0253 0.00777 0.00551 0.00617 0.0218 0.0234 0.0130 0.0111 0.00827 0.0109 0.0261 0.0193 0.0131 0.00836 0.00098
8.71 11.3 10.4 15.9 11.41 5.71 1.71 1.31 1.46 4.84 5.06 2.75 2.16 1.67 2.18 5.33 3.63 2.46 1.569 0.1841
0.0235 0.0279 0.0351 0.0391 0.0284 0.0152 0.09493 0.00290 0.00332 0.0135 0.0153 0.00886 0.00864 0.00611 0.00819 0.0189 0.0159 0.0108 0.00686 0.80081
0.0672 0.0880 0.0796 0.123 0.0885 0.0441 0.0132 0.0103 0.0114 0.0373 0.0388 0.0210 0.0162 0.0126 0.0165 0.0405 0.0271 0.0184 0.0117 0.00137
Total
0.457
0.294
0.76
*Source composition ene and coronene. t Source composition $ Source composition 4 Source composition
100
normalized to the total PAH mass with retention times between napththalnormalized to the sum of the 20 identified PAHs. normalized to the total emission of volatile organic compounds. normalized to the total emission of PMlO.
Table 5. Source composition of tunnel highway emission Source composition, weight percentage of categorical pollutant PAH
TPAH*
ZOPAH?
TVOCsj
TPMlO$
Naphthalene Acenaphthylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Retene Cyclop(cd)pyrene Benz(a)anthracene Chrysene Benzo(b)fluoranthene Benzo(k)fluoranthene Benzo(e)pyrene Benzo(a)pyrene Indeno Dibenz(ah)anthracene Benzo(ghi)perylene Coronene
2.10 0.125 0.0395 0.09 14 0.0693 0.0403 0.0230 0.0422 0.0164 0.0257 0.0198 0.0193 0.00888 0.00878 0.0112 0.0110 0.00215 0.00234 0.00367 bd
76.2 4.76 1.63 3.83 3.19 1.75 1.11 1.74 0.731 0.891 0.759 0.741 0.456 0.424 0.586 0.623 0.194 0.147 0.187 bd
0.1655 0.0125 0.00221 0.00487 0.00274 0.00226 0.00128 0.00156 0.@0083 0.00113 0.00103 0.@0080 0.@0048 0.00054 0.00074 0.00088 0.00025 O.WO24 0.00044 bd
1.88 0.125 0.0321 0.0748 0.0565
Total
2.66
* Source composition normalized lene and coronene. t Source composition normalized $ Source composition normalized 8 Source composition normalized bd: below the detection limit.
100
0.200
0.0349 0.0204 0.0307 0.0132 0.0182 0.0152 0.0144 0.00792 0.00794 0.0108 0.0114 0.00302 0.00273 0.00448 bd 2.36
to the total PAH mass with retention times between naphthato the sum of the 20 identified PAHs. to the total emission of volatile organic compounds. to the total emission of PMlO.
N. R. KHALILI
538
et al.
Table 6. Source composition of gasoline engines emission Source composition, weight percentage of categorical pollutant PAH
TPAH*
20PAHt
TVOCsS
TPMlO$
Naphthalene Acenaphthylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Retene Cyclop(cd)pyrene Benz(a)anthracene Chrysene Benzo(b)fluoranthene Benzo(k)fluoranthene Benzo(e)pyrene Benzo(a)pyrene Indeno Dibenz(ah)anthracenelj Benzo(ghi)perylene Coronene
1.59 0.0508 0.0369 0.0972 0.0622 0.0274 0.0458 0.0982 0.0370 0.0346 0.0101 0.0131 0.01538 0.01188 0.101 0.0247 bd 0.0121 0.0022 1 0.0030
55.62 2.23 1.52 4.56 5.84 1.32 3.09 8.35 2.61 1.78 0.7997 0.328 0.383 0.296 7.55 1.8441 bd 1.53 0.0532 0.0844
0.139 0.00480 0.00286 0.00907 0.00843 0.00282 0.00509 0.0124 0.00465 0.00383 0.00141 0.00134 0.00157 0.00121 0.0130 0.00315 bd 0.00187 0.00022 0.00034
0.611 0.0189 0.0159 0.0368 0.0193 0.0159 0.0159 0.0321 0.0116 0.0116 0.00306 0.00433 0.00505 0.00390 0.0318 0.00771 bd 0.00357 0.00070 0.00111
Total
2.28
0.217
0.845
100
* Source composition normalized to the total PAH mass with retention times between naphthalene and coronene. t Source composition normalized to the sum of the 20 identified PAHs. 3 Source composition normalized to the total emission of volatile organic compounds. §Source composition normalized to the total emission of PMlO. 1 Only one measurement. bd: below the detection limit.
Table 7. Source composition of wood combustion emission Source composition, weight percentage of categorical pollutant PAH
TPAH’
20PAHt
TVOCsS
TPMlQ
Naphthalene Acenaphthylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Retene Cyclop(cd)pyrene Benz(a)anthracene Chrysene Benzo(b)fluoranthene Benzo(k)fluoranthene Benzo(e)pyrene Be.nzo(a)pyrene Indeno Dibenz(ah)anthracene Benzo(ghi)pe.rylene Coronene
0.566 2.42 0.0657 0.150 0.320 0.0491 0.126 0.131 0.00612 0.0230 0.0268 0.0407 0.0313 0.06698 0.293 0.3087 bd bd bd bd
10.7 49.1 1.36 3.45 5.81 9.33 2.56 2.69 0.110 0.556 0.0498 0.883 0.627 1.18 5.22 5.39 bd bd bd bd
0.189 0.874 0.0244 0.0621 0.102 0.165 0.0457 0.0481 0.00195 0.0101 0.00880 0.0158 0.0112 0.0207 0.0917 0.0945 bd bd bd bd
0.0569 0.261 0.00731 0.0185 0.0308 0.0496 0.0136 0.0143 0.00059 0.00299 0.00265 0.00473 0.00335 0.00626 0.0276 0.0285 bd bd bd bd
Total
5.10
1.77
0.533
* Source composition normalized lene and coronene. t Source composition normalized $ Source composition normalized 0 Source composition normalized bd: below the detection limit.
100
to the total PAH mass with retention times between naphthato the sum of the 20 identified PAHs. to the total emission of volatile organic compounds. to the total emission of PMlO.
213 + 165 12 k 8.33 3.6 &-2.1 8.7 k 5.8 5.7 & 2.4 3.7 f 2.2 2.2 + 1.4 3.9 * 3.3 1.5 * 1.0 2.4 + 2.3 2.0 +_2.1 1.7 f 1.3 0.77 f 0.23 0.79 & 0.17 1.0 1.1 f 0.35 0.24 f 0.23 0.24 k 0.16 0.37 & 0.26 bd
Tunnel
28 k40 9.9 + 5.9 11 f 6.5 11 + 8.7 7.4 f 6.6 3.3 k 2.7 1.1 f 0.71 0.81 f 0.87 1.0 f 0.90 2.4 f 2.1 2.6 +_ 1.6 1.4 + 0.62 0.91 f 0.26 0.76 * 0.31 1.0 1.9 * 1.1 1.3 * 1.1 0.51 f 0.67 0.60 * 0.43 0.026
Diesel
o.Z++ 0.047tt 0.046tt
9.8 k 13 0.33 f 0.33 0.10 f 0.15 0.59 f 0.35 0.59 f 0.35 0.21 + 0.15 0.34 * 0.00 0.85 & 0.38 0.36 k 0.03 0.30 f 0.19 0.10 * 0.06 0.12 f 0.17 0.14 + 0.20 0.11 f 0.16 1.0 1.0
Gasoline
* Particulate and gas phase PAHs (this study). t- 11 Particulate phase PAHs only (Source: Benner and Gordon, 1989). ** Ratio to benzo(a)pyrene. tt Only one measurement. bd: below the detection limit of this study.
Naphthalene Acenaphthylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Retene Cyclop(cd)pyrene Benz(a)anthracene Chrysene Benzo(b)fluoranthene Benzo(k)fluoranthene Benzo(e)pyrene Benzo(a)pyrene Indeno(l,2,3,cd)pyrene Dibenz(ah)anthracene Benzo(ghi)perylene Coronene
PAHs
Chicago*
1.0 0.2-0.2 0.3-1.3 bd 0.4-2.6 0.3-1.1
1.0 1.1 * 0.9 + bd 1.6 k 0.9 * 0.5 0.4
0.2 0.3
0.6-0.9
Lincolnj Tunnel
4.6 f 2.5 1.5 f 0.3
4.5 & 1.9 6.3 k 3.3
Baltimore? Tunnel
1.0 1.2 0.8 bd 1.8 0.9
5.3 1.2 1.8
FRG§ Tunnel
bd 1.3 + 0.8
1.0 1.0 * 0.7
3.6 & 1.8 5.4 + 3.4
42 k 3
bd 2.9 + 0.9
1.0 1.0 f 0.7
2.5 * 0.9 2.7 + 1
10 * 4
Gasoline
TsuburanoT Diesel
Table 8. Ratios of PAHs to benzo(e)pyrene and benzo(a)pyrene
1.0 0.8-2.0 0.7-1.5 bd 2.0-3.0
2.9-5.5
1.0-2.0 0.6-1.7
Caldecott 11 ma Tunnel
bd bd
0.1
2.4 12 0.3 1.1 1.2 2.1 0.66 0.71 0.02 0.18 0.10 0.25 0.16 0.22 1.0 1.0 bd
0.1
0.2
1.0 0.6
1.0 3.3 0.3 0.2
6.2 7.4
Wood combustion**
Chicago Freeman
N. R. KHALILI et al.
540
Table 9. Ratios of PAHs to benzo(e)pyrene and benzo(a)pyrene Diesel*
Wood combustiont Guenther et al. (1988fi
Chicago, 1991
PAHs Naphthalene Acenaphthylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Retene Cyclop(cd)pyrene Benz(a)anthracene Chrysene Benzo(b)fluorantheneT Benzo(k)fluoranthene Beno(e)pyrene Benzo(a)pyrene Indeno(l,2,3,cd)pyrene Dibenz(ah)anthracene Benzo(ghi)perylene Coronene
28 + 40 9.9 * 5.9 11 + 6.5 11 f 8.7 7.4 f 6.6 3.3 + 2.7 1.1 f 0.71 0.81 k 0.8 1.0 + 0.90 2.4 + 2.1 2.6 k 1.6 1.4 &-0.62 0.91 f 0.2 0.76 + 0.31 1.0 1.9 * 1.1 1.3 + 1.1 0.51 f 0.67 0.60 f 0.43 0.026
Westerholm et al. Chicago, 1991 (1991)$
1966 f 88 + 159 k 87 +
2 0.71 0.6 1.3
1.2 * 3.1 + 19 f 2.0 f
1.07 1.9 0.64 1.1
2.4 12 0.3 1.1 1.2 2.1 0.66 0.71 0.02 0.18 0.10 0.25 0.16 0.22 1.0 1.0 bd bd bd bd
Fairbanks
80 12 21 20 30 1.8 3.2 5.0 6.6
Oak wood
15 4.3 6.1 5.9 1.5 1.5 2.3 1.6
3.0 1.0 1.8
0.64 1.0 0.76
0.8 1.2
0.29
*Calculated ratio to benzo(e)pyrene. t Calculated ratio to benzo(a)pyrene. JBoth gas and particulates phase PAHs were used in the calculations. Particulates and gas phase PAHs were collected on Pallflex T60A20 filters and polyurethane foam (PUF), respectively. Samples were analyzed by GC/MC. §The sampler used in this study consisted of PUF and 102 mm Teflon filter. Samples were analyzed by GC/MS. 1 Measured concentration of benzo(b,j,k)fluoranthene in the Westerholm and Guenther studies.
Table 10. Source distribution of the percentage of PAHs to the total mass of 20 PAHs
PAH* 2-ring 3-ring 4-ring 5-ring 6-ring 7-ring
Tunnel 76 16 4.3 3.1 0.38 bd
Diesel engines 8.7 56 10 18 5.2 0.18t
Gasoline engines 55 18 12 13 0.053 0.082
Coke oven 89 8.9 0.97 0.22 0.014 bd
Wood combustion 11 69 6.6 13 bd bd
* 2-ring: naphthalene; 3-ring: acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, and retene; 4-ring: fluoranthene, pyrene, benz(a)anthracene, chrysene, and triphenylene; 5-ring: cyclopenta(c,d)pyrene, benzo(b, k)fluoranthene, benzo(a, e)pyrene, dibenzo(ghi)perylene; 6-ring: indeno( 1,2,3,cd)pyrene and benzo(ghi)pyrene; 7-ring: coronene. t One measurement. bd: below the detection limit of this study.
utilizing the results of simultaneous measurements of categorical pollutants for each sample. The fingerprints for coke ovens, highway tunnels, diesel engines,
gasoline engines and wood combustion (Tables 2-7) were determined by dividing the concentration of individual measured PAH in each source sample into the measured categorical pollutants for that sample. The categorical pollutants included (a) total concentration of detected compounds with retention times between naphthalene and coronene (TPAH) (the aver-
age PAH response factor was used to convert area to mass), (b) total concentration of the 20 PAHs measured in this study (20 PAHs), (c) total concentration of VOCs, and (d) total concentration of PMlO. The source fingerprints in the tables were determined by calculating the source compositions for each source sample, and averaging the compositions for each category. Since the total PAH concentration, 20 PAHs, total VOCs, and total PM10 varied for different sources, the ratio of individual PAHs to the total
PAH source fingerprints
PAHs is different far each source. The fingerprints obtained have been successfully used in a preliminary chemical mass balance receptor modeling for PAHs in Chicago (Khalili, 1992). Mobile sources (highmwaytunnels, diesel and gasoline engines)
The six PAHs which on average had the highest concentrations in tr,affic samples were naphthalene, acenaphthylene, fluorene, phenanthrene, pyrene, and acenaphthene. In diesel engine samples, two and three ring PAHs contributed the most to the total mass. The predominant PAHs in the diesel emissions were fluorene, naphthalene, acenaphthylene, phenanthrene, and anthracene. On average the predominate PAHs in gasoline engine samlples were naphthalene, fluorene, benzo(e)pyrene, acenaphthylene, pyrene, and acenaphthene. The heavy molecular weight five and six ring PAHs were bellow the detection limits of this study for most of the samples. Coke ovens
The results of the analysis of coke oven samples indicated that two and three ring PAHs were responsible for the majority of the total measured PAHs in the coke oven area. Predominant PAHs in the coke oven emissions were naphthalene, acenaphthylene, phenanthrene, fluorene, anthracene, and fluoranthene. Total PAH concentrations averaged approximately 25 pgrne3 which is lo- 1to lo-’ of the typical concentration range of PAHs found in the working environment near coke plants (Jones and Leber, 1980). Wood combustion
The predominate PAHs in the wood smoke emission samples were acenaphthylene, naphthalene, anthracene, phenanthrene, benzo(a)pyrene, and benzo(e)pyrene. These findings agree fairly well with a study by Freeman who showed that PAHs that are produced during the pyrolysis of wood and are found in the smoke include anthracene, phenanthrene, dibenz(ah)anthracene, fluoranthene, benzo(ghi)fluoranthene, benzo(b)fluoranthene, benzo(ghi)perylene, benzo(a)pyrene, benzo(e)pyrene, cyclopenta(cd)pyrene, and some methylated substances (Freeman and Cattel, 1990). In the Freeman study a conventional high-volume sampler was used to collect airborne particulate matters on a glass fiber filter. Samples in the Freeman study were analyzed by a high performance liquid chromatograph (HPLC) system. The high concentration of coronene found by Freeman in bushfires is important since coronene is often used as a marker for motor vehicles, particularly gasoline-fueled vehicles (Freeman and Cattel, 1990). In summary the concentrations of individual PAHs in the highway tunnel, diesel engines, gasoline engines, and wood combustion samples in Chicago and those reported by others were normalized to those of
541
benzo(e)pyrene and benzo(a)pyrene to ease the comparison between the results of this study and others (Tables 8 and 9). The ratios of heavier molecular weight PAHs such as indeno(l,2,3,cd)pyrene, benzo(ghi)perylene, dibenz(ah)anthracene and coronene to benzo(e)pyrene for Chicago highway tunnel samples were similar to those reported by Benner et al. (1989). In Benner et al. (1989), suspended particulate matter was collected by using a high-volume sampler. Samples were analyzed by a liquid gas chromatography system. The ratios obtained for the gasoline and diesel engine vehicles for the Chicago study showed a good agreement with the Tsuburano data reported by Benner and Gordon. Note that Benner and Gordon did not study the concentrations of two and three ring PAHs, and comparisons are not made for those PAHs. Westerholm et al. (1991) measured the concentrations of both gas and particulate phase PAHs in the emissions from heavy-duty-diesel vehicles during transient driving conditions. Comparison indicated that calculated ratios of measured PAHs to benzo(e)pyrene for phenanthrene, anthracene, fluoranthene, and pyrene were significantly higher for data reported by Westerholm (Table 9). The observed differences are attributed to the employment of different sampling techniques and analytical methods. The concentrations of PAHs measured in the wood combustion samples in this study were normalized to benzo(a)pyrene and the calculated ratios compared to those reported for Freeman and Cattel (1990) and Guenther et al. (1988). In both the Freeman study and this study, the ratios obtained for particulate phase PAHs such as benz(a)anthracene, chrysene, benzo(b)fluoranthene, and benzo(k)fluoranthene were in good agreement. However, the ratios of PAHs to benzo(a)pyrene had much higher values in the Guenther study than those obtained in this study (Table 9). In general the ratios obtained in this study and those reported in other studies for the particulate phase PAHs were similar; however the ratios of lower molecular weight PAHs to benzo(e)pyrene had higher values for this study (Chang, 1991). Mass distribution of PAHs in different sources
The PAH phase distributions by the number of benzene rings are presented in Table 10. Low molecular weight PAHs (two and three rings) such as naphthalene (in coke ovens) and acenaphthylene (in wood combustion samples) accounted for the majority of the mass in all of the samples. Naphthalene accounted for the majority of the mass in coke oven, highway tunnel, and gasoline engine samples. Diesel engines and wood combustion samples did not have a significant concentration of naphthalene in their emissions. For wood combustion two and three ring PAHs were responsible for 70% of the total concentration of 20 PAHs. Six ring PAHs such as indeno(l,2,3-cd)pyrene and benzo(ghi)perylene were detected mostly in the highway tunnel, diesel and gasoline engine samples.
N. R. KHALILI et al.
542 CONCLUSION
AND SUMMARY
To evaluate the chemical composition of the major sources of PAHs in the Chicago metropolitan area, a study of major PAH sources was conducted during 1990-1991. The sources sampled were coke ovens, highway vehicles, diesel engines, gasoline engines and wood combustion. Results of this study were verified by comparing the ratio of measured PAHs to benzo(e)pyrene and benzo(a)pyrene with those ratios reported for other studies. This comparison showed a similarity between the ratios obtained for particulate phase PAHs. However lower molecular weight PAHs had higher values for their ratios in this study because both gas and particulate phase PAHs were measured. Two and three ring PAHs were responsible for the majority of the total PAH mass, in general 98,76,92, 73 and 80% of coke ovens, diesel engines, highway tunnels, gasoline engines and wood combustion, respectively. Source fingerprints were obtained by averaging the ratios of individual PAH concentrations divided by the measured total concentration of categorical pollutants such as total measured mass with retention times between naphthalene and coronene, the mass of 20 PAHs measured in this study, total VOCs, and total PMlO. Since concentrations of the categorical pollutants were different for individual samples, the patterns obtained for source fingerprints relative to different pollutants were different. The fingerprints presented have been used in preliminary chemical mass balance receptor modeling calculations in Chicago (Khalili, 1992). Acknowkdgements-We would like to thank Mrs Jean Graft Tetercycz from University of Illinois in Chicago, and Pao E. Chang from Illinois Institute of Technology, for their participation and time during the source sampling. We also thank the USEPA Grant R-814715-01-0 for the office of exploratory research for the partial support of this project.
REFERENCES Benner B. A., Gordon G. E. and Wise S. A. (1989) Mobile sources of atmospheric polycyclic aromatic hydrocarbons: a roadway tunnel study. Envir. Sci. Technol. 23, 1269-1277. Byrne M., Coons S., Goyer M., Harris J., Perwak J. (ADL), Cruse P., DeRosier R., Moss K and Wendt S. (Acurex) (1982) An Exposure and Risk Assessmentfor Benzo{a}pyrene and Other Pofycyclic Aromatic Hydrocarbons: Volume III. Anthracene, Acenaphthylene, Fluoranthene, Fluorene, Phenanthrene and Pyrene, pp. 4-29, EPA-440/4-85-020.
Arthur D. Little, Cambridge, Massachusetts. Chang P. E. (1991) An evaluation of PAH emissions from vehicles, coke oven and wood combustion sources. Master’s thesis, Pritzker Department of Environmental Engineering, Illinois Institute of Technology, Chicago, Illinois.
Chuang J. C., Hannan S. W. and Wilson N. K. (1987) Field comparison of polyurethane foam and XAD-2 resin for air sampling of polynuclear aromatic hydrocarbons. Envir. Sci. TechnoL 21, 798-804.
Daisey J. M., Leyko M. A. and Kneip T. J. (1979) Polynuclear Aromatic Hydrocarbons, p. 201. Ann Arbor Science, Michigan. Freeman D. J. and Cattel C. R. (1990) Wood burning as a source of atmospheric polycyclic aromatic hydrocarbons. Envir. Sci. TechnoL 24, 1581-1585.
Gordon R. J. and Bryan R. J. (1973) Patterns in airborne polynuclear hydrocarbon concentrations at four Los Angeles sites. Envir. Sci. Technol. 7, 1050-1053.. Gordon G. E. (1988) Receptor models. Envir. Sci. Technol. 22, 1132-1142.
Guenther F. R., Chesler S. N., Gordon G. E. and Zoller W. H. (1988) Residential wood combustion: a source of atmospheric polycyclic aromatic hydrocarbons. J. High Resolution Chromatogr. Chromatogr. Commun. 11,761-766. Jones P. W. and Leber P. (1980) Polynuclear Aromatic Hydrocarbons: 3rd Int. Symp. on Chemistry and Biology Carcinogenesis and Mutagenesis. Ann Arbor Science,
Michigan. Kenski D. M. (1991) Receptor modeling of volatile organic compounds in Detroit, Chicago, and Bealmount. MS. thesis, School of Public Health, University of Illinois in Chicago. Khalili N. R. (1992) Atmospheric polycyclic aromatic hydrocarbons in Chicago: characteristics and receptor modeling. Ph.D. thesis, Pritzker Department of Environmental Engineering, Illinois Institute of Technology, Chicago, Illinois. Lee M. I., Novotny M. V. and Bartle K. D. (1981) Analytical Chemistry of Polycyclic Aromatic Compounds. Academic Press, New York. Pyysalo H., Tuominen J., WickstrBm K., Skytta E. and Tikkanen L. (1987) Polycyclic organic material (POM) in urban air. Fractionation, chemical analysis and genotoxicity of particulate and vapor phases in an industrial town in Finland. Atmospheric Environment 21,1167-l 180. Ramdahl T. (1983) Polycyclic aromatic ketons in environmental samples. Envir. Sci. Technol. 17, 666-670. Ramdahl T., Becher G. and Bjgseth A. (1982). Nitrated polycyclic aromatic hydrocarbons in urban air particles. Envir. Sci. Technol. 16, 861-865.
Scheff P. A., Wadden R. A. and Allen R. J. (1984) Development and validation of chemical element mass balance for Chicago. Envir. Sci. Technol. 18, 923-931. Tuominen J.. Salomma S.. Pvvsalo H.. Skvtta E.. Tikkanen L. Nurmela T., Sorsa M.,‘Poijola V.,‘Sa& M. And Himberg K. (1988) Polynuclear aromatic compounds and genotoxicity in particulate and vapor phases of ambient air: effect of traffic, season and meteorological conditions. Envir. Sci. Technol. 22, 1228-1234.
Wadden R. A., Scheff P. A., Lin J., Lee H., Graf-Teterycz J., Keehan K.. Kenski D.. Milz S.. Holsen T. and Khalili N. (1991) Two’phase receptor modkling. Presented at the 84th Annual Meeting of the AWMA, Vancouver, BC. Westerholm R. N., Almen J., Li H., Rannug J. U., Egeback K. E. and Grlgg K. (1991) Chemical and biological characterization of particulate-semivolatile-, and gasphase associated compound in diluted heavy-duty diesel exhausts: a comparison of three different semivolatilephase samplers. Envir. Sci. Technol. 25, 322-338. Yamasaki H., Kuwata K. and Myomoto H. (1982) Effect of ambient temperature on aspects of airborne polycyclic aromatic hydrocarbons. Envir. Sci. TechnoL 16, 189-194.
Atmospheric
Environment Vol. 29, No. 4, pp. 533-542, 1995 Cowrixht 0 1995 Elsevier Science Ltd Printed in &eat Britain. All rights reserved 1352-2310/95 $9.50 + 0.00
13522310(94)0027M
PAH SOURCE FINGERPRINTS FOR COKE OVENS, DIESEL AND GASOLINE ENGINES, HIGHWAY TUNNELS, AND WOOD COMBUSTION EMISSIONS NASRIN
R. KHALILI,*
PETER A. SCHEFFt
and THOMAS
M. HOLSEN*
*Pritzker Department of Environmental Engineering, Illinois Institute of Technology, Chicago, IL 60616, U.S.A.; tEnvironmenta1 and Occupational Health Sciences, University of Illinois at Chicago, School of Public Health, P.O. Box 6998, M/C 922, Chicago, IL 60680, U.S.A. (First received 10 April 1993 and injnalform
16 July 1994)
Abstract-To evaluate the chemical composition (source fingerprint) of the major sources of polyaromatic hydrocarbons (PAHs) in the Chicago metropolitan area, a study of major PAH sources was conducted during 1990- 1992. In this study, a modified high-volume sampling method (PS-1 sampler) was employed to collect airborne PAHs in both the particulate and gas phases. Hewlett Packard 5890 gas chromatographs equipped with the flame ionization and mass spectrometer detectors (GC/FID and GC/MS) were used to analyze the samples. The sources sampled were: coke ovens, highway vehicles, heavy-duty diesel engines, gasoline engines and wood combustion. Results of this study showed that two and three ring PAHs were responsible for 98,76,92,73 and 80% of the total concentration of measured 20 PAHs for coke ovens, diesel engines, highway tunnels, gasoline engines and wood combustion samples, respectively. Six ring PAHs such as indeno(l,2,3&)pyrene and benzo(ghi)perylene were mostly below the detection limit of this study and only detected in the highway tunnel, diesel and gasoline engine samples. The source fingerprints were obtained by averaging the ratios of individual PAH concentrations to the total concentration of categorical pollutants including: (a) total measured mass of PAHs with retention times between naphthalene and coronene, (b) the mass of the 20 PAHs measured in this study, (c) total VOCs, and (d) total PMlO. Since concentrations of the above categorical pollutants were different for individual samples and different sources, the (chemical composition patterns obtained for each categorical pollutant were different. T’he source fingerprints have been developed for use in chemical mass balance receptor modeling calculations. Key word index: PAH, source fingerprint, chemical mass balance.
INTRODUCTION
Polyaromatic hydrocarbons (PAHs) are formed by incomplete combust.ion or pyrolysis of organic material containing carbon and hydrogen (Jones and Leber, 1980). They are multi-ringed compounds and many are known to be carcinogenic (Lee et al., 1981; Byrne et al., 1982). Interest in the carcinogenic effects of combustion products dades back at least 200 years, when Sir Percival Pott noted an increase in scrotal cancer among chimney sweeps in London. Association of the cancer with a specific chemical contained in combustion products was strengthened in 1933 when the PAH, benzo(a)pyrene, was isolated from chimney soot (Freeman and Cattel, 1990). The continuing interest in PAHs in air is due t,o the results of laboratory studies which have found that many other PAHs are also carcinogenic (Jones and Leber, 1980; Lee et al., 1981). Although numerous researchers have measured PAH concentration:< in ambient air, very few studies link their presence to a specific source. Motor vehicles are thought to be the major source of atmospheric
PAHs in the United States, accounting for 35% of the
yearly total. Aluminum production and forest fires each contribute 17%, followed by residential wood combustion, coke manufacturing, power generation and incineration which emit 12, 11, 6 and 3% of the yearly total, respectively (Benner et al., 1989). To understand the relationship between sources of air pollution and observed air quality, a variety of efforts including development of the chemical mass balance receptor models (CMB) have been made in recent years (Scheff et al., 1984). CMB models use the chemical and physical characteristics of both gases and particles measured at sources and receptors to both identify the presence of and to quantify source contributions to the receptor (Gordon, 1988). This model consists of a least-squares solution to a set of linear equations which expresses each receptor concentration of a chemical species as a linear sum of the product of source composition and total source contributions. Input data to the model include the source composition as the fractional amount of selected species in the emissions from each source category, the receptor concentrations of the selected species and appropriate uncertainty estimates. The CMB models 533
N. R. KHALILI et al.
534
have been applied to organic species (Gordon, 1988; Kenski, 1991). Modeling with organic chemicals, however, is limited due to difficulties associated with analytical methods and the availability of reliable chemical composition data. This paper presents the results of a study conducted to determine the chemical composition of major sources of PAHs in the Chicago metropolitan area. Emissions from coke ovens, vehicles in a highway tunnel, diesel engines, gasoline engines and wood combustion were quantitatively evaluated using an optimized method for sampling and analyzing PAHs present in atmospheric aerosols and gases with a sampling time of 2-4 h (Chang, 1991).
EXPERIMENTAL DESIGN
In general, organic air pollutants can be divided into two phases according to the different sampling techniques: (1) the particulate phase, and (2) the gas phase consisting of semivolatile and volatile compounds with boiling points higher than 100°C (Tuominen et al., 1988). PAHs have a wide range of vapor pressure and a knowledge of the distribution of these compounds between gas and particulate phases is important for the development of a sampling plan (Chuang et al., 1987; Pyysalo et al., 1987; Yamasaki et al., 1982). The sampling equipment used in this study was a semivolatile high-volume sampler model PS-1 (General Metal Works Inc.). The PS-1 sampling train is designed to collect suspended airborne particulate matter on a filter and vapor phase compounds on a backup sorbent. Particles were collected on 11 cm diameter glass micro fiber filters. The gas phase PAHs were collected in a modified cartridge containing XAD-2 resin sandwiched between layers of polyurethane foam (PUF). This system was found to retain 99% of the naphththalene, the most volatile PAH measured in this study, and therefore the compound most likely to break through the sorbent during the 4 h sampling period (Khalili, 1992). The qualitative/quantitative identification of PAHs was performed using a Hewlett Packard 5890 gas chromatograph equipped with an autosampler and a flame ionization detector. To confirm the peak identification, 10% of the samples were also analyzed by a Hewlett Packard 5890 gas chromatograph equipped with a mass spectrometer detector (GC/MS). Where possible, results of this study were compared to the ratios of PAHs to indicator PAHs such as benzo(e)pyrene and benzo(a)pyrene reported in other studies. To determine the source fingerprints, measured concentrations of PAHs for each sample were normalized to the concentrations of categorical pollutants for that sample and source fingerprints were calculated by averaging the mass fractions for individual PAHs from each sample in each source category. Sampling program
A total of 19 samples from selected PAH sources in the Chicago area were collected and analyzed during 1990-1992. Five samples of emissions from urban vehicles were taken in heavily traveled tunnels during evening rush hours (4.OC-7.00 p.m.). The first tunnel sample was taken along the Kennedy Expressway and the other four tunnel samples were taken along Lower Wacker Drive at the intersection with Michigan Avenue in downtown Chicago. Five samples were collected 100 m directly downwind of a coke plant located in southeast Chicago. During sampling, there were no other operating steel making facilities near the coke plant so that the samples collected were not influenced
by other steel making processes. The coke oven samples were all obtained between 5:OOand 1O:OOp.m. Four samples of heavy-duty diesel engine emissions were obtained in a Chicago Transit Authority bus parking garage on the north side of Chicago (public transportation bus stopping facility). Diesel engine emission samples were collected on Friday and Monday mornings between 4.00 and 7.00 a.m. The two samples collected on Friday represent warm-engine emissions and two samples collected on Monday represent cold-start engine emissions. Emissions from gasoline engines were collected from a public parking garage located in downtown Chicago. Three samples that represent warm-engine operation were taken between 6:30 and 900 a.m. Two samples of emissions were collected from fireplaces, burning seasoned oak wood which is the most common type of wood burned in the Chicago area. These samples were collected on the roof of a house directly downwind of the chimney. Selected PAHs
A group of 20 PAHs were selected for analysis. They include a group of suspected carcinogens including benzo (a)pyrene, benzo(b)fluoranthene, and indeno(l,2,3,cd)pyrene. In addition the concentrations of coronene, phenanthrene, anthracene, fluoranthene, pyrene, acenaphthene, triphenylene, cyclopenta(cd)pyrene, and benzo(ghi)perylene were measured. These compounds have been found in the ambient air (Pyysalo et al., 1987), and some of them have been identified as potential tracers of PAH emissions (Ramdahl et al., 1982). Naphthalene, acenaphthylene, benzo(k)fluoranthene, chrysene, (1,2,5,6)-dibenz(ah)anthracene, and fluorene are the remaining compounds on the EPA PAH priority pollutants list and were included in the study of completeness. Benzo(e)pyrene was also included because PAH concentrations are often reported relative to it. The final compound analyzed, retene, has been suggested as a marker for coniferous wood smoke (Ramdahl, 1983). Sample preparation
Source samples were prepared for analysis within 24 h after collection. Preparation included sample extraction, volume reduction (concentration), sample cleanup, final concentration, and GC analysis. The filter and cartridge were Soxhlet extracted together for 24 h with a mixture of acetone:hexane (60:40). The extract was concentrated to 1 ml under purified N, and total extracted organics were fractionated on a silica gel cleanup column (Pyysalo et al., 1987). The selected fraction (PAH group) was collected and concentrated under purified N, gas to 0.2 ml. Treated samples were subsequently analyzed by GC/FID. The qualitative/quantitative identification of PAHs was performed using a Hewlett Packard 5890 gas chromatograph equipped with an autosampler and a flame ionization detector. To confirm the peak identification, 10% of the samples were also analyzed by a Hewlett Packard 5890 gas chromatograph equipped with a mass spectrometer detector (GC/MS). The gas chromatograph was calibrated with certified PAH standards. A master standard solution of 22 PAHs (20 PAHs, and two internal standards) was used in the GC calibration processes. Quantification of individual PAHs in the sample was determined by direct injection of a known concentration of a calibration mixture (master PAH standard) to determine area response per injected mass of each compound. In the GC analysis a 50 m Ultra-2,0.32 mm i.d. column coated with 5% methyl silicon was used with high purity helium \yith a flow rate of 1 mlmin-’ at 29o”C, as a carrier gas. A 3 ~1 sample was injected into the splitless injector at 300°C. The initial oven temperature was 50°C; after injection the oven temperature was rapidly increased to 100°C at a rate of 20”Cmin-‘, 100 to 290°C with a rate of 3°C min- 1 and held for 40 min. The FID detector was
PAH source fingerprints operated at 300°C utihzing pure air and hydrogen gas at a rate of 400 and 30 ml :min- i, respectively. The averaged value of response factors for individual PAHs (RF,) was calculated based on repeated injection of various concentrations of the master PAH standard solution. The retention times (RT,) of individual PAH compounds as well as internal standards for compound identification were also determined in the calibration processes. As a part of the quality control/quality assurance effort (QC/QA), the efficiency of each individual sampling technique and analytical procedure has been independently investigated by the addition of a known amount of internal standards to the master PAH standard solution and field samples. In general, total recovery obtained for individual PAHs in this study ranged from 80 to 95%. A detailed discussion of the recovery efficiencies is presented1 elsewhere (Khalili, 1992). The results of analysis performed on field blanks indicated an insignificant contamination level lower than the GC detection limit (i.e. lower than 0.124 ng, GC detection limit of naphthalene). The detection limit for each PAH was obtained by injecting sequentially dimted standard solutions to the GC. The instrument detection limit increased with increasing molecule weight and ranged from 0.124 to 1.42 ng, for naphthalene and coronene, respectively. PM10 and VOC samples Particulate matter (PMIO) and volatile organic compounds (VOCs) samples were simultaneously collected with each PAH sample. PM 10concentrations were measured with a medium flow (4 cfm) PM10 sampler, fitted with a Teflon filter. Proton induced X-ray emission (PIXE) and neutron activation analyses (NAA) were carried out on the filters for elemental analysis. Volatile organic compounds (VOCs) were also collected in 6 L electropolished stainless steel canisters using a constant massflow controlled bellows pump. Analysis for 57 organics plus total non-methane organic compounds (NMOC) carbon was carried out using a high resolution gas chromatograph (HRGC) fitted with a cryogenic trap and flame ionization and electron capture detectors (FID and ECD) (Wadden et al., 1991).
535 RESULTS AND DISCUSSION
The average concentrations obtained for each PAH in the emissions from the five sources studied are presented in Table 1. The fingerprints for coke ovens, highway tunnels, diesel engines, gasoline engines and wood combustion are presented in Tables 2-7. The concentrations of individual PAHs in the sampled sources in Chicago and those reported by others were normalized to those of benzo(e)pyrene and benzo(a)pyrene to ease the comparison between the results of this study and others (Tables 8 and 9). The calculated mass distributions of PAHs in different sources are shown in Table 10.
Source jingerprints Studies performed during the last decades showed that PAHs have significant variation in their composition for different combustion sources (Gordon and Bryan, 1973; Gordon, 1988; Daisey et al., 1979) and their fingerprints if available can be used in the sources identification models such as CMB receptor models. Reviewing the recent studies indicated that due to the existing differences between selected sampling techniques and/or adopted analytical procedures a great deal of inconsistency exists between reported data for PAH source fingerprints. Up to this date the important problem associated with the application of the chemical mass balance receptor models for organic air pollutants such as PAHs, has been the absence of a reliable source fingerprint. In this study efforts were made to develop the chemical composition (fingerprints) of the major sources of the PAHs in Chicago
Table 1. Average concentration (pg rnm3) of individual PAHs in sampled sources in Chicago
PAHs Naohthalene Acdnaphthyle ne Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Retene Cyclop(cd)pyrene Benz(a)anthracene Chrysene Benzo(b)fluoranthene Benzo(k)fluoranthene Benzo(e)pyrene Benzo(a)pyrene Indeno(l,2,3,cd)pyrene Dibenz(ah)anthracene Benzo(ghi)perylene Coronene
Coke oven 22.4 0.747 0.023 0.502 0.500
0.158 0.0883 0.0563 0.00957 0.00220 0.00759 0.0147 0.00477 0.00801 0.0116 0.00533 0.0011 bd
0.000690 bd
*Warm engine samples. t One measurement. bd: below the detection limit of this study.
Diesel engines* 0.386 0.464 0.566 0.651 0.472 0.251 0.0806 0.0489 0.0558 0.222 0.249 0.143 0.137 0.0977 0.130 0.302 0.250 0.170 0.108 0.025t
Tunnel 8.03 0.445 0.168 0.406 0.300 0.177 0.117 0.193 0.0787 0.100 0.0902
0.0779 0.0436 0.0412 0.0555 0.0626 0.0200 0.0147 0.0170 bd
Gasoline engines 2.46 0.0708 0.0377 0.123 0.0398 0.0388 0.0446 0.0719 0.0437 0.05 14 0.00586 0.0283 0.0330 0.0255 0.122 0.0270 bd bd 0.00918t 0.0145t
Wood combustion 0.402 1.83 0.0515 0.128 0.219 0.350 0.0959 0.100 0.0041 0.0296 0.0187 0.0328 0.0234 0.0446 0.197 0.203 bd bd bd bd
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Table 2. Source composition of coke oven emission Source composition, weight percentage of categorical pollutant PAH
TPAH*
Naphthalene Acenapththylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Retene Cyclop(cd)pyrene Benz(a)anthracene Chrysene Benzo(b)fluoranthene Benzo(k)fluoranthene Benzo(e)pyrene Benzo(a)pyrene Indeno Dibenz(ah)anthracene Benzo(ghi)perylene Coronene
7.01 0.216 0.0122 0.200 0.221 0.0549 0.0425 0.0300 0.00384 0.00125 0.00524 0.00901 0.00242 0.00556 0.00734 0.00323 0.00109 bd 0.0007 bd
Total
7.82
* Source composition lene and coronene. t Source composition $ Source composition 8 Source composition
20PAHt 89.8 2.94 0.149 2.47 2.62 0.690 0.489 0.334 0.0465 0.0145 0.0558 0.0971 0.0278 0.0611 0.0839 0.0358 0.00886 bd 0.00535 bd 100
TVOCsj
TPMlO$
1.49 0.0552 0.00376 0.0459 0.0526 0.0134 0.0101 0.00657 0.00085 0.00047 0.00162 0.00222 0.00047 0.00162 0.00211 0.00081 0.0000 bd 0.00000 bd
22.6 0.763 0.0276 0.529 0.527 0.160 0.0954 0.0624 0.0100 0.00259 0.00935 0.0163 0.00533 0.00935 0.0140 0.00621 0.00134 bd 0.00081 bd
1.69
24.8
normalized to the total PAH mass with retention times between naphthanormalized to the sum of the 20 identified PAHs. normalized to the total emission of volatile organic compounds. normalized to the total emission of PM 10.
Table 3. Source composition of diesel engines Source composition, weight percentage of categorical pollutant PAH
TPAH*
Naphthalene Acenaphthylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Retene Cyclop(cd)pyrene Benz(a)anthracene Chrysene Benzo(b)fluoranthene Benzo(k)fluoranthene Bcnzo(e)pyrene Benzo(a)pyrene Indeno Dibenz(ah)athracene Benzo(ghi)perylene Coronene
0.163 0.0958 0.165 0.133 0.0958 0.0384 0.0158 0.00667 0.0119 0.0206 0.0249 0.0155 0.0143 0.00732 0.0132 0.0195 0.0265 0.00707 0.0112 0.00049
Total
0.886
* Source composition lene and coronene. t Source composition $ Source composition §Source composition
20PAHt 24.5 10.7 13.5 13.2 9.11 4.18 1.46 0.900 1.19 3.07 3.44 1.94 1.58 1.14 1.58 3.12 2.64 1.345 1.17 0.0921 100
TVOCs$
TPMlO$
0.3860 0.0688 0.0820 0.0484 0.0255 0.0143 0.00533 0.00350 0.00417 0.0132 0.0171 0.00948 0.00797 0.00769 0.00852 0.0144 0.0112 0.00777 0.00598 0.00040
1.25 0.217 0.237 0.1466 0.0741 0.0412 0.0148 0.0115 0.0130 0.0389 0.0492 0.0262 0.0192 0.0212 0.0220 0.0359 0.0225 0.0170 0.0135 0.00069
0.741
2.27
normalized to the total PAH mass with retention times between naphthanormalized to the sum of the 20 identified PAHs. normalized to the total emission of volatile organic compounds. normalized to the total emission of PMlO.
PAH source fingerprints
537
Table 4. Source composition of warm diesel engine Source composition, weight percentage of categorical pollutant PAH
TPAH*
20PAHt
TVOCsf:
TPMlO$
Naphthalene Acenaphthlylene AcenaphthLene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Retene Cyclop(cd)pyrene Benz(a)anthracene Chrysene Benzo(b)fluoranthene Benzo(k)fluoranthene Benzo(e)pyrene Benzo(a)pyrene Indeno Dibenz(ah)~anthracene Benzo(ghi)perylene Coronene
0.0387 0.0490 0.0501 0.0689 0.0495 0.0253 0.00777 0.00551 0.00617 0.0218 0.0234 0.0130 0.0111 0.00827 0.0109 0.0261 0.0193 0.0131 0.00836 0.00098
8.71 11.3 10.4 15.9 11.41 5.71 1.71 1.31 1.46 4.84 5.06 2.75 2.16 1.67 2.18 5.33 3.63 2.46 1.569 0.1841
0.0235 0.0279 0.0351 0.0391 0.0284 0.0152 0.09493 0.00290 0.00332 0.0135 0.0153 0.00886 0.00864 0.00611 0.00819 0.0189 0.0159 0.0108 0.00686 0.80081
0.0672 0.0880 0.0796 0.123 0.0885 0.0441 0.0132 0.0103 0.0114 0.0373 0.0388 0.0210 0.0162 0.0126 0.0165 0.0405 0.0271 0.0184 0.0117 0.00137
Total
0.457
0.294
0.76
*Source composition ene and coronene. t Source composition $ Source composition 4 Source composition
100
normalized to the total PAH mass with retention times between napththalnormalized to the sum of the 20 identified PAHs. normalized to the total emission of volatile organic compounds. normalized to the total emission of PMlO.
Table 5. Source composition of tunnel highway emission Source composition, weight percentage of categorical pollutant PAH
TPAH*
ZOPAH?
TVOCsj
TPMlO$
Naphthalene Acenaphthylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Retene Cyclop(cd)pyrene Benz(a)anthracene Chrysene Benzo(b)fluoranthene Benzo(k)fluoranthene Benzo(e)pyrene Benzo(a)pyrene Indeno Dibenz(ah)anthracene Benzo(ghi)perylene Coronene
2.10 0.125 0.0395 0.09 14 0.0693 0.0403 0.0230 0.0422 0.0164 0.0257 0.0198 0.0193 0.00888 0.00878 0.0112 0.0110 0.00215 0.00234 0.00367 bd
76.2 4.76 1.63 3.83 3.19 1.75 1.11 1.74 0.731 0.891 0.759 0.741 0.456 0.424 0.586 0.623 0.194 0.147 0.187 bd
0.1655 0.0125 0.00221 0.00487 0.00274 0.00226 0.00128 0.00156 0.@0083 0.00113 0.00103 0.@0080 0.@0048 0.00054 0.00074 0.00088 0.00025 O.WO24 0.00044 bd
1.88 0.125 0.0321 0.0748 0.0565
Total
2.66
* Source composition normalized lene and coronene. t Source composition normalized $ Source composition normalized 8 Source composition normalized bd: below the detection limit.
100
0.200
0.0349 0.0204 0.0307 0.0132 0.0182 0.0152 0.0144 0.00792 0.00794 0.0108 0.0114 0.00302 0.00273 0.00448 bd 2.36
to the total PAH mass with retention times between naphthato the sum of the 20 identified PAHs. to the total emission of volatile organic compounds. to the total emission of PMlO.
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et al.
Table 6. Source composition of gasoline engines emission Source composition, weight percentage of categorical pollutant PAH
TPAH*
20PAHt
TVOCsS
TPMlO$
Naphthalene Acenaphthylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Retene Cyclop(cd)pyrene Benz(a)anthracene Chrysene Benzo(b)fluoranthene Benzo(k)fluoranthene Benzo(e)pyrene Benzo(a)pyrene Indeno Dibenz(ah)anthracenelj Benzo(ghi)perylene Coronene
1.59 0.0508 0.0369 0.0972 0.0622 0.0274 0.0458 0.0982 0.0370 0.0346 0.0101 0.0131 0.01538 0.01188 0.101 0.0247 bd 0.0121 0.0022 1 0.0030
55.62 2.23 1.52 4.56 5.84 1.32 3.09 8.35 2.61 1.78 0.7997 0.328 0.383 0.296 7.55 1.8441 bd 1.53 0.0532 0.0844
0.139 0.00480 0.00286 0.00907 0.00843 0.00282 0.00509 0.0124 0.00465 0.00383 0.00141 0.00134 0.00157 0.00121 0.0130 0.00315 bd 0.00187 0.00022 0.00034
0.611 0.0189 0.0159 0.0368 0.0193 0.0159 0.0159 0.0321 0.0116 0.0116 0.00306 0.00433 0.00505 0.00390 0.0318 0.00771 bd 0.00357 0.00070 0.00111
Total
2.28
0.217
0.845
100
* Source composition normalized to the total PAH mass with retention times between naphthalene and coronene. t Source composition normalized to the sum of the 20 identified PAHs. 3 Source composition normalized to the total emission of volatile organic compounds. §Source composition normalized to the total emission of PMlO. 1 Only one measurement. bd: below the detection limit.
Table 7. Source composition of wood combustion emission Source composition, weight percentage of categorical pollutant PAH
TPAH’
20PAHt
TVOCsS
TPMlQ
Naphthalene Acenaphthylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Retene Cyclop(cd)pyrene Benz(a)anthracene Chrysene Benzo(b)fluoranthene Benzo(k)fluoranthene Benzo(e)pyrene Be.nzo(a)pyrene Indeno Dibenz(ah)anthracene Benzo(ghi)pe.rylene Coronene
0.566 2.42 0.0657 0.150 0.320 0.0491 0.126 0.131 0.00612 0.0230 0.0268 0.0407 0.0313 0.06698 0.293 0.3087 bd bd bd bd
10.7 49.1 1.36 3.45 5.81 9.33 2.56 2.69 0.110 0.556 0.0498 0.883 0.627 1.18 5.22 5.39 bd bd bd bd
0.189 0.874 0.0244 0.0621 0.102 0.165 0.0457 0.0481 0.00195 0.0101 0.00880 0.0158 0.0112 0.0207 0.0917 0.0945 bd bd bd bd
0.0569 0.261 0.00731 0.0185 0.0308 0.0496 0.0136 0.0143 0.00059 0.00299 0.00265 0.00473 0.00335 0.00626 0.0276 0.0285 bd bd bd bd
Total
5.10
1.77
0.533
* Source composition normalized lene and coronene. t Source composition normalized $ Source composition normalized 0 Source composition normalized bd: below the detection limit.
100
to the total PAH mass with retention times between naphthato the sum of the 20 identified PAHs. to the total emission of volatile organic compounds. to the total emission of PMlO.
213 + 165 12 k 8.33 3.6 &-2.1 8.7 k 5.8 5.7 & 2.4 3.7 f 2.2 2.2 + 1.4 3.9 * 3.3 1.5 * 1.0 2.4 + 2.3 2.0 +_2.1 1.7 f 1.3 0.77 f 0.23 0.79 & 0.17 1.0 1.1 f 0.35 0.24 f 0.23 0.24 k 0.16 0.37 & 0.26 bd
Tunnel
28 k40 9.9 + 5.9 11 f 6.5 11 + 8.7 7.4 f 6.6 3.3 k 2.7 1.1 f 0.71 0.81 f 0.87 1.0 f 0.90 2.4 f 2.1 2.6 +_ 1.6 1.4 + 0.62 0.91 f 0.26 0.76 * 0.31 1.0 1.9 * 1.1 1.3 * 1.1 0.51 f 0.67 0.60 * 0.43 0.026
Diesel
o.Z++ 0.047tt 0.046tt
9.8 k 13 0.33 f 0.33 0.10 f 0.15 0.59 f 0.35 0.59 f 0.35 0.21 + 0.15 0.34 * 0.00 0.85 & 0.38 0.36 k 0.03 0.30 f 0.19 0.10 * 0.06 0.12 f 0.17 0.14 + 0.20 0.11 f 0.16 1.0 1.0
Gasoline
* Particulate and gas phase PAHs (this study). t- 11 Particulate phase PAHs only (Source: Benner and Gordon, 1989). ** Ratio to benzo(a)pyrene. tt Only one measurement. bd: below the detection limit of this study.
Naphthalene Acenaphthylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Retene Cyclop(cd)pyrene Benz(a)anthracene Chrysene Benzo(b)fluoranthene Benzo(k)fluoranthene Benzo(e)pyrene Benzo(a)pyrene Indeno(l,2,3,cd)pyrene Dibenz(ah)anthracene Benzo(ghi)perylene Coronene
PAHs
Chicago*
1.0 0.2-0.2 0.3-1.3 bd 0.4-2.6 0.3-1.1
1.0 1.1 * 0.9 + bd 1.6 k 0.9 * 0.5 0.4
0.2 0.3
0.6-0.9
Lincolnj Tunnel
4.6 f 2.5 1.5 f 0.3
4.5 & 1.9 6.3 k 3.3
Baltimore? Tunnel
1.0 1.2 0.8 bd 1.8 0.9
5.3 1.2 1.8
FRG§ Tunnel
bd 1.3 + 0.8
1.0 1.0 * 0.7
3.6 & 1.8 5.4 + 3.4
42 k 3
bd 2.9 + 0.9
1.0 1.0 f 0.7
2.5 * 0.9 2.7 + 1
10 * 4
Gasoline
TsuburanoT Diesel
Table 8. Ratios of PAHs to benzo(e)pyrene and benzo(a)pyrene
1.0 0.8-2.0 0.7-1.5 bd 2.0-3.0
2.9-5.5
1.0-2.0 0.6-1.7
Caldecott 11 ma Tunnel
bd bd
0.1
2.4 12 0.3 1.1 1.2 2.1 0.66 0.71 0.02 0.18 0.10 0.25 0.16 0.22 1.0 1.0 bd
0.1
0.2
1.0 0.6
1.0 3.3 0.3 0.2
6.2 7.4
Wood combustion**
Chicago Freeman
N. R. KHALILI et al.
540
Table 9. Ratios of PAHs to benzo(e)pyrene and benzo(a)pyrene Diesel*
Wood combustiont Guenther et al. (1988fi
Chicago, 1991
PAHs Naphthalene Acenaphthylene Acenaphthene Fluorene Phenanthrene Anthracene Fluoranthene Pyrene Retene Cyclop(cd)pyrene Benz(a)anthracene Chrysene Benzo(b)fluorantheneT Benzo(k)fluoranthene Beno(e)pyrene Benzo(a)pyrene Indeno(l,2,3,cd)pyrene Dibenz(ah)anthracene Benzo(ghi)perylene Coronene
28 + 40 9.9 * 5.9 11 + 6.5 11 f 8.7 7.4 f 6.6 3.3 + 2.7 1.1 f 0.71 0.81 k 0.8 1.0 + 0.90 2.4 + 2.1 2.6 k 1.6 1.4 &-0.62 0.91 f 0.2 0.76 + 0.31 1.0 1.9 * 1.1 1.3 + 1.1 0.51 f 0.67 0.60 f 0.43 0.026
Westerholm et al. Chicago, 1991 (1991)$
1966 f 88 + 159 k 87 +
2 0.71 0.6 1.3
1.2 * 3.1 + 19 f 2.0 f
1.07 1.9 0.64 1.1
2.4 12 0.3 1.1 1.2 2.1 0.66 0.71 0.02 0.18 0.10 0.25 0.16 0.22 1.0 1.0 bd bd bd bd
Fairbanks
80 12 21 20 30 1.8 3.2 5.0 6.6
Oak wood
15 4.3 6.1 5.9 1.5 1.5 2.3 1.6
3.0 1.0 1.8
0.64 1.0 0.76
0.8 1.2
0.29
*Calculated ratio to benzo(e)pyrene. t Calculated ratio to benzo(a)pyrene. JBoth gas and particulates phase PAHs were used in the calculations. Particulates and gas phase PAHs were collected on Pallflex T60A20 filters and polyurethane foam (PUF), respectively. Samples were analyzed by GC/MC. §The sampler used in this study consisted of PUF and 102 mm Teflon filter. Samples were analyzed by GC/MS. 1 Measured concentration of benzo(b,j,k)fluoranthene in the Westerholm and Guenther studies.
Table 10. Source distribution of the percentage of PAHs to the total mass of 20 PAHs
PAH* 2-ring 3-ring 4-ring 5-ring 6-ring 7-ring
Tunnel 76 16 4.3 3.1 0.38 bd
Diesel engines 8.7 56 10 18 5.2 0.18t
Gasoline engines 55 18 12 13 0.053 0.082
Coke oven 89 8.9 0.97 0.22 0.014 bd
Wood combustion 11 69 6.6 13 bd bd
* 2-ring: naphthalene; 3-ring: acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, and retene; 4-ring: fluoranthene, pyrene, benz(a)anthracene, chrysene, and triphenylene; 5-ring: cyclopenta(c,d)pyrene, benzo(b, k)fluoranthene, benzo(a, e)pyrene, dibenzo(ghi)perylene; 6-ring: indeno( 1,2,3,cd)pyrene and benzo(ghi)pyrene; 7-ring: coronene. t One measurement. bd: below the detection limit of this study.
utilizing the results of simultaneous measurements of categorical pollutants for each sample. The fingerprints for coke ovens, highway tunnels, diesel engines,
gasoline engines and wood combustion (Tables 2-7) were determined by dividing the concentration of individual measured PAH in each source sample into the measured categorical pollutants for that sample. The categorical pollutants included (a) total concentration of detected compounds with retention times between naphthalene and coronene (TPAH) (the aver-
age PAH response factor was used to convert area to mass), (b) total concentration of the 20 PAHs measured in this study (20 PAHs), (c) total concentration of VOCs, and (d) total concentration of PMlO. The source fingerprints in the tables were determined by calculating the source compositions for each source sample, and averaging the compositions for each category. Since the total PAH concentration, 20 PAHs, total VOCs, and total PM10 varied for different sources, the ratio of individual PAHs to the total
PAH source fingerprints
PAHs is different far each source. The fingerprints obtained have been successfully used in a preliminary chemical mass balance receptor modeling for PAHs in Chicago (Khalili, 1992). Mobile sources (highmwaytunnels, diesel and gasoline engines)
The six PAHs which on average had the highest concentrations in tr,affic samples were naphthalene, acenaphthylene, fluorene, phenanthrene, pyrene, and acenaphthene. In diesel engine samples, two and three ring PAHs contributed the most to the total mass. The predominant PAHs in the diesel emissions were fluorene, naphthalene, acenaphthylene, phenanthrene, and anthracene. On average the predominate PAHs in gasoline engine samlples were naphthalene, fluorene, benzo(e)pyrene, acenaphthylene, pyrene, and acenaphthene. The heavy molecular weight five and six ring PAHs were bellow the detection limits of this study for most of the samples. Coke ovens
The results of the analysis of coke oven samples indicated that two and three ring PAHs were responsible for the majority of the total measured PAHs in the coke oven area. Predominant PAHs in the coke oven emissions were naphthalene, acenaphthylene, phenanthrene, fluorene, anthracene, and fluoranthene. Total PAH concentrations averaged approximately 25 pgrne3 which is lo- 1to lo-’ of the typical concentration range of PAHs found in the working environment near coke plants (Jones and Leber, 1980). Wood combustion
The predominate PAHs in the wood smoke emission samples were acenaphthylene, naphthalene, anthracene, phenanthrene, benzo(a)pyrene, and benzo(e)pyrene. These findings agree fairly well with a study by Freeman who showed that PAHs that are produced during the pyrolysis of wood and are found in the smoke include anthracene, phenanthrene, dibenz(ah)anthracene, fluoranthene, benzo(ghi)fluoranthene, benzo(b)fluoranthene, benzo(ghi)perylene, benzo(a)pyrene, benzo(e)pyrene, cyclopenta(cd)pyrene, and some methylated substances (Freeman and Cattel, 1990). In the Freeman study a conventional high-volume sampler was used to collect airborne particulate matters on a glass fiber filter. Samples in the Freeman study were analyzed by a high performance liquid chromatograph (HPLC) system. The high concentration of coronene found by Freeman in bushfires is important since coronene is often used as a marker for motor vehicles, particularly gasoline-fueled vehicles (Freeman and Cattel, 1990). In summary the concentrations of individual PAHs in the highway tunnel, diesel engines, gasoline engines, and wood combustion samples in Chicago and those reported by others were normalized to those of
541
benzo(e)pyrene and benzo(a)pyrene to ease the comparison between the results of this study and others (Tables 8 and 9). The ratios of heavier molecular weight PAHs such as indeno(l,2,3,cd)pyrene, benzo(ghi)perylene, dibenz(ah)anthracene and coronene to benzo(e)pyrene for Chicago highway tunnel samples were similar to those reported by Benner et al. (1989). In Benner et al. (1989), suspended particulate matter was collected by using a high-volume sampler. Samples were analyzed by a liquid gas chromatography system. The ratios obtained for the gasoline and diesel engine vehicles for the Chicago study showed a good agreement with the Tsuburano data reported by Benner and Gordon. Note that Benner and Gordon did not study the concentrations of two and three ring PAHs, and comparisons are not made for those PAHs. Westerholm et al. (1991) measured the concentrations of both gas and particulate phase PAHs in the emissions from heavy-duty-diesel vehicles during transient driving conditions. Comparison indicated that calculated ratios of measured PAHs to benzo(e)pyrene for phenanthrene, anthracene, fluoranthene, and pyrene were significantly higher for data reported by Westerholm (Table 9). The observed differences are attributed to the employment of different sampling techniques and analytical methods. The concentrations of PAHs measured in the wood combustion samples in this study were normalized to benzo(a)pyrene and the calculated ratios compared to those reported for Freeman and Cattel (1990) and Guenther et al. (1988). In both the Freeman study and this study, the ratios obtained for particulate phase PAHs such as benz(a)anthracene, chrysene, benzo(b)fluoranthene, and benzo(k)fluoranthene were in good agreement. However, the ratios of PAHs to benzo(a)pyrene had much higher values in the Guenther study than those obtained in this study (Table 9). In general the ratios obtained in this study and those reported in other studies for the particulate phase PAHs were similar; however the ratios of lower molecular weight PAHs to benzo(e)pyrene had higher values for this study (Chang, 1991). Mass distribution of PAHs in different sources
The PAH phase distributions by the number of benzene rings are presented in Table 10. Low molecular weight PAHs (two and three rings) such as naphthalene (in coke ovens) and acenaphthylene (in wood combustion samples) accounted for the majority of the mass in all of the samples. Naphthalene accounted for the majority of the mass in coke oven, highway tunnel, and gasoline engine samples. Diesel engines and wood combustion samples did not have a significant concentration of naphthalene in their emissions. For wood combustion two and three ring PAHs were responsible for 70% of the total concentration of 20 PAHs. Six ring PAHs such as indeno(l,2,3-cd)pyrene and benzo(ghi)perylene were detected mostly in the highway tunnel, diesel and gasoline engine samples.
N. R. KHALILI et al.
542 CONCLUSION
AND SUMMARY
To evaluate the chemical composition of the major sources of PAHs in the Chicago metropolitan area, a study of major PAH sources was conducted during 1990-1991. The sources sampled were coke ovens, highway vehicles, diesel engines, gasoline engines and wood combustion. Results of this study were verified by comparing the ratio of measured PAHs to benzo(e)pyrene and benzo(a)pyrene with those ratios reported for other studies. This comparison showed a similarity between the ratios obtained for particulate phase PAHs. However lower molecular weight PAHs had higher values for their ratios in this study because both gas and particulate phase PAHs were measured. Two and three ring PAHs were responsible for the majority of the total PAH mass, in general 98,76,92, 73 and 80% of coke ovens, diesel engines, highway tunnels, gasoline engines and wood combustion, respectively. Source fingerprints were obtained by averaging the ratios of individual PAH concentrations divided by the measured total concentration of categorical pollutants such as total measured mass with retention times between naphthalene and coronene, the mass of 20 PAHs measured in this study, total VOCs, and total PMlO. Since concentrations of the categorical pollutants were different for individual samples, the patterns obtained for source fingerprints relative to different pollutants were different. The fingerprints presented have been used in preliminary chemical mass balance receptor modeling calculations in Chicago (Khalili, 1992). Acknowkdgements-We would like to thank Mrs Jean Graft Tetercycz from University of Illinois in Chicago, and Pao E. Chang from Illinois Institute of Technology, for their participation and time during the source sampling. We also thank the USEPA Grant R-814715-01-0 for the office of exploratory research for the partial support of this project.
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Arthur D. Little, Cambridge, Massachusetts. Chang P. E. (1991) An evaluation of PAH emissions from vehicles, coke oven and wood combustion sources. Master’s thesis, Pritzker Department of Environmental Engineering, Illinois Institute of Technology, Chicago, Illinois.
Chuang J. C., Hannan S. W. and Wilson N. K. (1987) Field comparison of polyurethane foam and XAD-2 resin for air sampling of polynuclear aromatic hydrocarbons. Envir. Sci. TechnoL 21, 798-804.
Daisey J. M., Leyko M. A. and Kneip T. J. (1979) Polynuclear Aromatic Hydrocarbons, p. 201. Ann Arbor Science, Michigan. Freeman D. J. and Cattel C. R. (1990) Wood burning as a source of atmospheric polycyclic aromatic hydrocarbons. Envir. Sci. TechnoL 24, 1581-1585.
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