pah source fingerprints for coke ovens, diesel and, gasoline engines, highway tunnels, and wood...

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

534 N. R. KHALILI et al.

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:OO and 1O:OO p.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 com- pleteness. 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 535

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 effici- ency 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 insignifi- cant 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 molecu- le 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 com-

pounds (VOCs) samples were simultaneously collected with each PAH sample. PM 10 concentrations 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. Ana- lysis for 57 organics plus total non-methane organic compounds (NMOC) carbon was carried out using a high resolution gas chromatograph (HRGC) fitted with a cryo- genic trap and flame ionization and electron capture detectors (FID and ECD) (Wadden et al., 1991).

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 Coke oven Diesel

engines* Tunnel Gasoline engines

Wood combustion

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

22.4 0.747 0.023 0.502

0.386 0.464 0.566 0.651 0.472 0.251 0.0806 0.0489

0.500 0.158 0.0883 0.0563 0.00957 0.0558 0.00220 0.222 0.00759 0.0147 0.00477 0.00801 0.0116 0.00533 0.0011

bd 0.000690

bd

0.249 0.143 0.137 0.0977 0.130 0.302 0.250 0.170 0.108 0.025t

8.03 2.46 0.445 0.0708 0.168 0.0377 0.406 0.123 0.300 0.0398 0.177 0.0388 0.117 0.0446 0.193 0.0719 0.0787 0.0437 0.100 0.05 14 0.0902 0.00586 0.0779 0.0283 0.0328 0.0436 0.0330 0.0234 0.0412 0.0255 0.0555 0.122 0.0626 0.0270 0.0200 bd 0.0147 bd 0.0170 0.00918t

bd 0.0145t

0.402 1.83 0.0515 0.128 0.219 0.350 0.0959 0.100 0.0041 0.0296 0.0187

0.0446 0.197 0.203

bd bd bd bd

*Warm engine samples. t One measurement. bd: below the detection limit of this study.


Table 2. Source composition of coke oven emission

Source composition, weight percentage of categorical pollutant

PAH TPAH* 20PAHt TVOCsj TPMlO$

Naphthalene 7.01 89.8 1.49 22.6 Acenapththylene 0.216 2.94 0.0552 0.763 Acenaphthene 0.0122 0.149 0.00376 0.0276 Fluorene 0.200 2.47 0.0459 0.529 Phenanthrene 0.221 2.62 0.0526 0.527 Anthracene 0.0549 0.690 0.0134 0.160 Fluoranthene 0.0425 0.489 0.0101 0.0954 Pyrene 0.0300 0.334 0.00657 0.0624 Retene 0.00384 0.0465 0.00085 0.0100 Cyclop(cd)pyrene 0.00125 0.0145 0.00047 0.00259 Benz(a)anthracene 0.00524 0.0558 0.00162 0.00935 Chrysene 0.00901 0.0971 0.00222 0.0163 Benzo(b)fluoranthene 0.00242 0.0278 0.00047 0.00533 Benzo(k)fluoranthene 0.00556 0.0611 0.00162 0.00935 Benzo(e)pyrene 0.00734 0.0839 0.00211 0.0140 Benzo(a)pyrene 0.00323 0.0358 0.0008 1 0.00621 Indeno 0.00109 0.00886 0.0000 0.00134 Dibenz(ah)anthracene bd bd bd bd Benzo(ghi)perylene 0.0007 0.00535 0.00000 0.00081 Coronene bd bd bd bd

Total 7.82 100 1.69 24.8

* 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. $ Source composition normalized to the total emission of volatile organic compounds. 8 Source composition normalized to the total emission of PM 10.

Table 3. Source composition of diesel engines


PAH TPAH* 20PAHt TVOCs$

Naphthalene 0.163 24.5 0.3860 Acenaphthylene 0.0958 10.7 0.0688 Acenaphthene 0.165 13.5 0.0820 Fluorene 0.133 13.2 0.0484 Phenanthrene 0.0958 9.11 0.0255 Anthracene 0.0384 4.18 0.0143 Fluoranthene 0.0158 1.46 0.00533 Pyrene 0.00667 0.900 0.00350 Retene 0.0119 1.19 0.00417 Cyclop(cd)pyrene 0.0206 3.07 0.0132 Benz(a)anthracene 0.0249 3.44 0.0171 Chrysene 0.0155 1.94 0.00948 Benzo(b)fluoranthene 0.0143 1.58 0.00797 Benzo(k)fluoranthene 0.00732 1.14 0.00769 Bcnzo(e)pyrene 0.0132 1.58 0.00852 Benzo(a)pyrene 0.0195 3.12 0.0144 Indeno 0.0265 2.64 0.0112 Dibenz(ah)athracene 0.00707 1.345 0.00777 Benzo(ghi)perylene 0.0112 1.17 0.00598 Coronene 0.00049 0.0921 0.00040

Total 0.886 100 0.741

TPMlO$

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

2.27


t Source composition normalized to the sum of the 20 identified PAHs. $ Source composition normalized to the total emission of volatile organic compounds. §Source composition normalized to the total emission of PMlO.


Table 4. Source composition of warm diesel engine


PAH TPAH* 20PAHt TVOCsf: TPMlO$

Naphthalene 0.0387 8.71 0.0235 0.0672 Acenaphthlylene 0.0490 11.3 0.0279 0.0880 AcenaphthLene 0.0501 10.4 0.0351 0.0796 Fluorene 0.0689 15.9 0.0391 0.123 Phenanthrene 0.0495 11.41 0.0284 0.0885 Anthracene 0.0253 5.71 0.0152 0.0441 Fluoranthene 0.00777 1.71 0.09493 0.0132 Pyrene 0.00551 1.31 0.00290 0.0103 Retene 0.00617 1.46 0.00332 0.0114 Cyclop(cd)pyrene 0.0218 4.84 0.0135 0.0373 Benz(a)anthracene 0.0234 5.06 0.0153 0.0388 Chrysene 0.0130 2.75 0.00886 0.0210 Benzo(b)fluoranthene 0.0111 2.16 0.00864 0.0162 Benzo(k)fluoranthene 0.00827 1.67 0.00611 0.0126 Benzo(e)pyrene 0.0109 2.18 0.00819 0.0165 Benzo(a)pyrene 0.0261 5.33 0.0189 0.0405 Indeno 0.0193 3.63 0.0159 0.0271 Dibenz(ah)~anthracene 0.0131 2.46 0.0108 0.0184 Benzo(ghi)perylene 0.00836 1.569 0.00686 0.0117 Coronene 0.00098 0.1841 0.80081 0.00137

Total 0.457 100 0.294 0.76

*Source composition normalized to the total PAH mass with retention times between napththal- ene and coronene.

t Source composition normalized to the sum of the 20 identified PAHs. $ Source composition normalized to the total emission of volatile organic compounds. 4 Source composition normalized to the total emission of PMlO.

Table 5. Source composition of tunnel highway emission


PAH TPAH* ZOPAH? TVOCsj TPMlO$

Naphthalene 2.10 76.2 Acenaphthylene 0.125 4.76 Acenaphthene 0.0395 1.63 Fluorene 0.09 14 3.83 Phenanthrene 0.0693 3.19 Anthracene 0.0403 1.75 Fluoranthene 0.0230 1.11 Pyrene 0.0422 1.74 Retene 0.0164 0.731 Cyclop(cd)pyrene 0.0257 0.891 Benz(a)anthracene 0.0198 0.759 Chrysene 0.0193 0.741 Benzo(b)fluoranthene 0.00888 0.456 Benzo(k)fluoranthene 0.00878 0.424 Benzo(e)pyrene 0.0112 0.586 Benzo(a)pyrene 0.0110 0.623 Indeno 0.00215 0.194 Dibenz(ah)anthracene 0.00234 0.147 Benzo(ghi)perylene 0.00367 0.187 Coronene bd bd

Total 2.66 100

0.1655 1.88 0.0125 0.125 0.00221 0.0321 0.00487 0.0748 0.00274 0.0565 0.00226 0.0349 0.00128 0.0204 0.00156 0.0307 0.@0083 0.0132 0.00113 0.0182 0.00103 0.0152 0.@0080 0.0144 0.@0048 0.00792 0.00054 0.00794 0.00074 0.0108 0.00088 0.0114 0.00025 0.00302 O.WO24 0.00273 0.00044 0.00448

bd bd

0.200 2.36


t Source composition normalized to the sum of the 20 identified PAHs. $ Source composition normalized to the total emission of volatile organic compounds. 8 Source composition normalized to the total emission of PMlO. bd: below the detection limit.


Table 6. Source composition of gasoline engines emission


PAH TPAH* 20PAHt TVOCsS TPMlO$

Naphthalene 1.59 55.62 0.139 0.611 Acenaphthylene 0.0508 2.23 0.00480 0.0189 Acenaphthene 0.0369 1.52 0.00286 0.0159 Fluorene 0.0972 4.56 0.00907 0.0368 Phenanthrene 0.0622 5.84 0.00843 0.0193 Anthracene 0.0274 1.32 0.00282 0.0159 Fluoranthene 0.0458 3.09 0.00509 0.0159 Pyrene 0.0982 8.35 0.0124 0.0321 Retene 0.0370 2.61 0.00465 0.0116 Cyclop(cd)pyrene 0.0346 1.78 0.00383 0.0116 Benz(a)anthracene 0.0101 0.7997 0.00141 0.00306 Chrysene 0.0131 0.328 0.00134 0.00433 Benzo(b)fluoranthene 0.01538 0.383 0.00157 0.00505 Benzo(k)fluoranthene 0.01188 0.296 0.00121 0.00390 Benzo(e)pyrene 0.101 7.55 0.0130 0.0318 Benzo(a)pyrene 0.0247 1.8441 0.00315 0.00771 Indeno bd bd bd bd Dibenz(ah)anthracenelj 0.0121 1.53 0.00187 0.00357 Benzo(ghi)perylene 0.0022 1 0.0532 0.00022 0.00070 Coronene 0.0030 0.0844 0.00034 0.00111

Total 2.28 100 0.217 0.845


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


PAH TPAH’

Naphthalene 0.566 Acenaphthylene 2.42 Acenaphthene 0.0657 Fluorene 0.150 Phenanthrene 0.320 Anthracene 0.0491 Fluoranthene 0.126 Pyrene 0.131 Retene 0.00612 Cyclop(cd)pyrene 0.0230 Benz(a)anthracene 0.0268 Chrysene 0.0407 Benzo(b)fluoranthene 0.0313 Benzo(k)fluoranthene 0.06698 Benzo(e)pyrene 0.293 Be.nzo(a)pyrene 0.3087 Indeno bd Dibenz(ah)anthracene bd Benzo(ghi)pe.rylene bd Coronene bd

Total 5.10

20PAHt TVOCsS TPMlQ

10.7 0.189 0.0569 49.1 0.874 0.261

1.36 0.0244 0.0073 1 3.45 0.0621 0.0185 5.81 0.102 0.0308 9.33 0.165 0.0496 2.56 0.0457 0.0136 2.69 0.0481 0.0143 0.110 0.00195 0.00059 0.556 0.0101 0.00299 0.0498 0.00880 0.00265 0.883 0.0158 0.00473 0.627 0.0112 0.00335 1.18 0.0207 0.00626 5.22 0.0917 0.0276 5.39 0.0945 0.0285

bd bd bd bd bd bd bd bd bd bd bd bd

100 1.77 0.533


t Source composition normalized to the sum of the 20 identified PAHs. $ Source composition normalized to the total emission of volatile organic compounds. 0 Source composition normalized to the total emission of PMlO. bd: below the detection limit.

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Table 9. Ratios of PAHs to benzo(e)pyrene and benzo(a)pyrene

Diesel* Wood combustiont

Guenther et al. (1988fi Westerholm et al.

PAHs Chicago, 1991 (1991)$ Chicago, 1991 Fairbanks Oak wood

Naphthalene 28 + 40 2.4 Acenaphthylene 9.9 * 5.9 12 Acenaphthene 11 + 6.5 0.3 Fluorene 11 f 8.7 1.1 Phenanthrene 7.4 f 6.6 1966 f 2 1.2 80 15 Anthracene 3.3 + 2.7 88 + 0.71 2.1 12 4.3 Fluoranthene 1.1 f 0.71 159 k 0.6 0.66 21 6.1 Pyrene 0.81 k 0.8 87 + 1.3 0.71 20 5.9 Retene 1.0 + 0.90 0.02 30 Cyclop(cd)pyrene 2.4 + 2.1 1.2 * 1.07 0.18 1.8 1.5 Benz(a)anthracene 2.6 k 1.6 3.1 + 1.9 0.10 3.2 1.5 Chrysene 1.4 &- 0.62 19 f 0.64 0.25 5.0 2.3 Benzo(b)fluorantheneT 0.91 f 0.2 2.0 f 1.1 0.16 6.6 1.6 Benzo(k)fluoranthene 0.76 + 0.31 0.22 Beno(e)pyrene 1.0 1.0 3.0 0.64 Benzo(a)pyrene 1.9 * 1.1 1.0 1.0 1.0 Indeno(l,2,3,cd)pyrene 1.3 + 1.1 bd 1.8 0.76 Dibenz(ah)anthracene 0.51 f 0.67 bd Benzo(ghi)perylene 0.60 f 0.43 bd 0.8 0.29 Coronene 0.026 bd 1.2

*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

Diesel Gasoline Wood PAH* Tunnel engines engines Coke oven combustion

2-ring 76 8.7 55 89 11 3-ring 16 56 18 8.9 69 4-ring 4.3 10 12 0.97 6.6 5-ring 3.1 18 13 0.22 13 6-ring 0.38 5.2 0.053 0.014 bd 7-ring bd 0.18t 0.082 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


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 (highmway tunnels, 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- 1 to 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 pro- duced 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 Free- man 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

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. Sam- ples 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 West- erholm (Table 9). The observed differences are at- tributed 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 Guen- ther 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.


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 parti- cipation and time during the source sampling. We also thank the USEPA Grant R-814715-01-0 for the office of explo- ratory 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.

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