Fontes de Hidrocarbonetos Policíclicos

Prévia do material em texto

<p>Environ. Sci. Technol. 1990, 24, 1581-1585</p><p>Woodburning as a Source of Atmospheric Polycyclic Aromatic Hydrocarbons</p><p>Diana J. Freeman and Frank C. R. Cattell"</p><p>Graduate School of the Environment, Macquarie University, New South Wales, 2 109, Australia</p><p>Airborne particulate matter containing polycyclic aro-</p><p>matic hydrocarbons derived from burning natural vege-</p><p>tation and paper products in a variety of ways was col-</p><p>lected and analyzed by HPLC. Similar profiles of com-</p><p>pounds resulted from most of the combustion sources that</p><p>do not involve fossil fuels and that are likely to contribute</p><p>to Sydney's atmospheric particulates. In addition, the</p><p>profiles did not change markedly as a result of reactions</p><p>occurring in the atmosphere or from reactions occurring</p><p>on the filter after collection. Concentrations of benzo-</p><p>[alpyrene and coronene were higher in the polycyclic</p><p>aromatic hydrocarbons derived from bush fires than from</p><p>other sources. Bush fires are likely to be a significant</p><p>source of exposure of the Sydney population to polycyclic</p><p>aromatic hydrocarbons.</p><p>~ ~</p><p>Introduct ion</p><p>Interest in the carcinogenic effects of combustion</p><p>products dates back at least 200 years, when Sir Percival</p><p>Pott noted an increase in scrotal cancer among chimney</p><p>sweeps in London ( I ) . Association of the cancer with a</p><p>chemical was strengthened in 1933 when the polycyclic</p><p>aromatic hydrocarbon (PAH) benzo[a] pyrene (BaP) was</p><p>isolated from chimney soot. Much of the interest in PAHs</p><p>in air since then has been focused on production from the</p><p>incomplete combustion of fossil fuels and on the single</p><p>PAH, BaP, which has been linked with cancer in labora-</p><p>tory studies and among certain occupations (2).</p><p>Much less work has been carried out to determine the</p><p>contribution of woodburning to the atmospheric burden</p><p>of PAHs, although concerns over the price and availability</p><p>of fossil fuels together with environmental concerns have</p><p>resulted in increased use of wood as a fuel in many de-</p><p>veloped countries, including Australia, since the early</p><p>1970s. Woodburning can generate high concentrations of</p><p>PAHs; total concentrations of 3000 pg m-3 and concen-</p><p>trations of 60 pg m-3 for BaP have been measured in flue</p><p>emissions from small residential stoves compared with</p><p>ambient PAH concentrations, which are usually of the</p><p>order of a few nanograms per cubic meter (3). As a result,</p><p>residential wood combustion can be a very significant</p><p>source of atmospheric aerosols containing PAHs, particu-</p><p>larly in the winter months ( 4 , 5 ) . Greenberg et al. have</p><p>shown that up to 98% of the BaP in New Jersey during</p><p>winter could arise from residential woodburning (5, 6) .</p><p>In Australia, in major cities as well as regional centers,</p><p>the impact of woodburning on air quality has been un-</p><p>derestimated in the past. In the state of New South Wales,</p><p>during 1983,193400 households (11% of the total house-</p><p>holds) used wood or another solid fuel as the major heating</p><p>source and this figure had increased to 225000 (14.6% of</p><p>houses) 2 years later (7).</p><p>In Sydney, Australia's most populous city, other im-</p><p>portant potential sources of PAHs that also do not arise</p><p>from fossil fuels are commercial and private incinerators,</p><p>combustion of domestic and garden waste in largely un-</p><p>controlled situations and, on occasions, bush fires, which</p><p>although very intermittent in nature can have a very</p><p>marked effect on air quality for periods of a few days.</p><p>Recently an estimate for the urban region of Sydney of the</p><p>contribution of burning of vegetation to air pollution has</p><p>been obtained based on carbon 14 isotope measurements.</p><p>These measurements indicate that as much as 91% of</p><p>particulate carbon arises from nonfossil fuel sources in</p><p>some leafy suburbs of Sydney, largely from the burning</p><p>of domestic litter (8). The high concentrations are con-</p><p>sistent with estimates that combustion of a tonne of plant</p><p>waste in a typical backyard burn can generate about 9 kg</p><p>of particulate matter (9). Even in the central business</p><p>district of Sydney, one-third of the carbon content of the</p><p>suspended particulate matter was of recent (i.e., nonfossil</p><p>fuel) origin, indicating the importance of wood and paper</p><p>burning within the builtup confines of the city (IO). The</p><p>only other major sources of particulate material containing</p><p>carbon in Sydney are emissions from gasoline- and die-</p><p>sel-fueled motor vehicles (11).</p><p>The purpose of this study was to examine the PAHs</p><p>produced in Sydney from burning wood and other vege-</p><p>tation and to see if the patterns of PAHs produced from</p><p>each of the nonfossil fuel sources were sufficiently similar</p><p>to each other but sufficiently different from the fossil fuel</p><p>sources to allow a source reconciliation to be carried out</p><p>on the observed proportions of PAHs in ambient air.</p><p>Exper imenta l Sect ion</p><p>Collection and Extraction of Organic Material.</p><p>Airborne particulate matter was collected on 20 X 25 cm</p><p>glass fiber filters (Pallflex Products Co.) for 30 min with</p><p>a conventional high-volume (hi-vol) sampler having a flow</p><p>of 1.0 m3/min. The glass fiber filters were equilibrated</p><p>at constant relative humidity and weighed before and after</p><p>exposure, and the collected material was extracted with</p><p>cyclohexane-methylene chloride 40:60 (100 mL) in an</p><p>ultrasonic bath for 30 min, followed by 2 X 10 min periods</p><p>with 2 X 50 mL of solvent. The crude combined extracts</p><p>were partially evaporated under vacuum in a water bath</p><p>at 40 "C. The remainder of the solvent was evaporated</p><p>under a stream of purified nitrogen at room temperature.</p><p>The sample was made to 100 pL with methylene chloride</p><p>prior to analysis.</p><p>Analysis of PAHs. The equipment used in this work</p><p>comprised a Waters HPLC system consisting of two 6000</p><p>A pumps, a U6K injector, a Model 450 variable-wavelength</p><p>optical absorbance detector set a t either 254 or 287 nm,</p><p>a radial compression module, and a radial PAH PAK</p><p>cartridge (polymeric C-18). The Model 840 data and</p><p>chromatography control station was interfaced with a</p><p>Hitachi F-1000 variable-wavelength fluorescent spectrom-</p><p>eter set a t an excitation wavelength of 300 nm and an</p><p>emission wavelength of 400 nm. Routinely, an aliquot of</p><p>20 pL was used and eluted by a linear gradient from</p><p>40:6G9010 of acetonitrile-water at a constant flow of 2.0</p><p>mL/min for 30 min. Identification of the PAHs and</p><p>calibration was effected by reference to responses of known</p><p>standards (Supelco Inc.). The validity of the PAH de-</p><p>termination in the extract was established by enrichment</p><p>with known PAHs and analysis at 254 and 287 nm. The</p><p>response ratios a t these two wavelengths were compared</p><p>with standards. In this study 10 compounds from the</p><p>standard EPA PAH mix of 16 PAHs were assayed as well</p><p>as coronene (COR). The EPA standards assayed were</p><p>fluoranthene (FLU), pyrene (PYR), benz[a]anthracene</p><p>(BaA), chrysene (CHR), benzo[b]fluoranthene (BbF),</p><p>0013-936X/90/0924-1581$02.50/0 @ 1990 American Chemical Society Environ. Sci. Technol., Vol. 24, No. 10, 1990 1581</p><p>Table 1. PAA Concentrations (rglg) of Particulate Matter from the Burning of Wood and Other Vegetation</p><p>sourceD</p><p>PAH 1 2 3 4 5 6 7 8 9 10</p><p>FLU 87.6 182 54.1 70.1 200 27.2 66.5 53.2 31.0 130</p><p>PYR 102 222 240 68.1 128 38.7 73.5 59.1 28.0 116</p><p>BaA 38.9 13.3 10.8 60.1 38.1 3.9 5.5 8.0 14.0 43.5</p><p>CHR 63.4 32.3 75.6 64.3 125 6.0 13.0 40.0 28.0 66.7</p><p>BbF 30.2 10.5 9.0 6.2 6.0 1.1 1.5 2.2 4.9 8.9</p><p>BkF 21.3 4.9 7.2 10.0 20.7 1.1 1.3 1.4 2.9 7.3</p><p>BaP 27.3 26.2 37.2 70.5 194 6.0 5.5 2.2 21.0 50.8</p><p>DbA 1.2 7.7 8.0 4.3 12.2 1.0 0.7 0.8 3.5 14.5</p><p>BghiP 5.8 11.0 6.0 10.2 8.2 1.5 1.5 2.0 3.5 14.5</p><p>IP 10.0 14.0 12.3 20.3 19.5 3.0 5.0 4.0 14.0 29.0</p><p>COR 0.7 0.7 0.6 1.0 26.0 0.1 1.3 1.2 2.8 5.9</p><p>"Sources: 1. Open wood fire burning Australian native wwd. 2. Open barbecue burning of Australian native plants. 3. Open barbecue</p><p>cooking of meat with Australian native plants as fuel. 4. Large-scale backyard bum of both native and introduced species and some</p><p>cardboard products. 5. Largescale</p><p>bush fire, consuming native plants only. 6. Leaves from Australian native vegetation burnt on an open</p><p>fire. 7. Wood from Australian native vegetation bumt on an open fire. 8. Commercial incinerator burning paper and cardboard products.</p><p>9. Cigarette mainstream and sideatream smoke. 10. Cigarette sidestream smoke.</p><p>benzo[k]fluorantbene (BkF), benzo[a]pyrene (BaP), di-</p><p>benz(a,h)anthracene (DbA), benzo[ghi]perylene (BghiP),</p><p>and indeno[cd]pyrene (IP). The more volatile PAHs were</p><p>deliberately excluded from the study since they can be</p><p>removed from the filter during collection.</p><p>Description of Combustion Types Sampled. (1)</p><p>Open Wood Fire Burning Australian Native Wood.</p><p>The domestic open wood fire consisted of a grate ap-</p><p>proximately 10 cm above the floor level upon which wood</p><p>was rested. The grate was completely open on three sides,</p><p>with the hack of the fireplace approximately 50 cm from</p><p>the rear edge of the grate. A copper hood conducted smoke</p><p>away out of the room and up the chimney. This fire</p><p>consumed approximately 10 kg of wood per hour and is</p><p>typical of fires used for heating Sydney homes.</p><p>(2) Open Barbecue Cooking of Meat with Austra-</p><p>lian Native Plants as Fuel. The burning of Australian</p><p>wood with and without meat to stimulate a barbecue took</p><p>place on a small portable cast-iron barbecue with the</p><p>supporting grid approximately 20 cm above the base plate,</p><p>and open on all four sides as well as from above.</p><p>(3) Large-Scale Backyard B u m of Both Native and</p><p>Introduced Species and Some Cardboard Products.</p><p>The large-scale backyard burn consisted of a mass of</p><p>predominantly old vegetation and some cardboard, 5 m</p><p>high and approximately 4 m wide and deep. Once the fre</p><p>had started, it was continuously fed with more vegetation</p><p>and burnt for about 2 b. This mix of vegetation and</p><p>cardboard fuels is typical of burns in the gardens of sub-</p><p>urban homes.</p><p>(4) Large-Scale Bush Fire, Consuming Native</p><p>Plants Only. The large-scale bush fire took place in a</p><p>National Park on the outskirts of Sydney and represented</p><p>total uncontrolled burning of native vegetation.</p><p>(5) Leaves and Wood from Australian Native Veg-</p><p>etation Burnt on a n Open Fire. Leaves and wood were</p><p>derived from native plants and burnt as described in (2)</p><p>above.</p><p>(6) Commercial Incinerator Burning Paper and</p><p>Cardboard Products. Thii incinerator was typical of one</p><p>employed on commercial premises. The dimensions of the</p><p>incinerator body, which consisted of a closed chamber,</p><p>were approximately 2 X 1 X 1 m3. Access to the chamber</p><p>was obtained by opening the casbiron door at ground leveL</p><p>The incinerator body was fitted with a chimney approx-</p><p>imately 5 m high.</p><p>For all of the collections the sampling period was less</p><p>than 1 h and the sampler, which was typically 3 m from</p><p>the combustion murce, was moved to ensure that sampliig</p><p>1582 Environ. Sci. Technol.. VoI. 24. No. 10. 1990</p><p>14 't iI</p><p>4</p><p>L BbF L BXF</p><p>BaP ObA BghiP IP COR</p><p>Flgure 1. Profile of PAHs from the burning of wocd and other vege-</p><p>tation.</p><p>was always from within the plume.</p><p>Results and Discussion</p><p>The PAH profiles in the emissions from various com-</p><p>bustion processes were measured and the results are shown</p><p>in Figure 1 and Table I. Results given in Figure 1 have</p><p>been normalized such that the peak for indeno[cdlpyrene</p><p>(IP) is given the value unity to facilitate comparison be-</p><p>tween samples containing different amounts of PAHs. IP</p><p>Table 11. Correlation Coefficients between Logarithmically Transformed PAH Concentrations from Different Sources</p><p>source0 1 2 3 4 5 6 7 8 9 10</p><p>1 1.000 0.813 0.831 0.868 0.578 0.845 0.767 0.785 0.769 0.728</p><p>2 1.000 0.943 0.848 0.644 0.983 0.876 0.831 0.834 0.907</p><p>3 1.000 0.873 0.678 0.949 0.818 0.800 0.846 0.876</p><p>4 LOO0 0.731 0.918 0.788 0.759 0.899 0.901</p><p>5 1.OOO 0.695 0.812 0.713 0.836 0.821</p><p>6 1.OOO 0.887 0.834 0.876 0.936</p><p>7 1.OOO 0.949 0.901 0.921</p><p>8 1.OOO 0.858 0.875</p><p>9 1.OOO 0.957</p><p>10 1.OOO</p><p>OSources: 1. Open wood fire burning Australian native wood. 2. Open barbecue burning of Australian native plants. 3. Open barbecue</p><p>cooking of meat with Australian native plants as fuel. 4. Large-scale backyard burn of both native and introduced species and some</p><p>cardboard products. 5. Large-scale bush fire, consuming native plants only. 6. Leaves from Australian native vegetation burnt on an open</p><p>fire. 7. Wood from Australian native vegetation burnt on an open fire. 8. Commercial incinerator burning paper and cardboard products.</p><p>9. Cigarette mainstream and sidestream smoke. 10. Cigarette sidestream smoke.</p><p>was chosen because it is present in reasonable quantities</p><p>and is involatile and unreactive. Although the PAH pro-</p><p>files from burning a variety of vegetation material in a</p><p>number of ways appear broadly similar, Table I does show</p><p>also that there are some significant differences.</p><p>The correspondence between the emissions from the</p><p>various sources was tested by a calculation of the corre-</p><p>lation between the logarithmically transformed PAH</p><p>concentrations for the different sources. A logarithmic</p><p>transformation was used because the concentrations more</p><p>closely fitted a log normal than a normal distribution. The</p><p>logarithmic transformation has the effect of reducing the</p><p>influence of extreme values on correlations. Table I1 shows</p><p>the correlation between the PAHs for the emission sources</p><p>in the present study. In general, correlation coefficients</p><p>between the various sources are greater than 0.8 although</p><p>the correlations between some sources and bush fires are</p><p>a little worse than this. Emissions of fluoranthene and</p><p>pyrene from cigarettes are low compared with most other</p><p>sources. This was not a significant problem for source</p><p>reconciliations of outdoor air quality, since cigarettes are</p><p>not a major source of PAHs in outdoor air and the more</p><p>volatile PAHs were not incorporated into the modeling</p><p>scheme, but it could be important for the source appor-</p><p>tionment of indoor air quality. The BaP and coronene</p><p>concentration for bush fires is high; in fact, the coronene</p><p>concentration from the bush fire is larger than that from</p><p>motor vehicles. The coronene to IP ratio is very variable</p><p>for all the sources compared with the other PAHs.</p><p>The high coronene concentration in bush fires is very</p><p>important because coronene is often used as a marker for</p><p>motor vehicles, particularly gasoline-fueled ones (12).</p><p>Although the samples for the bush fire were taken close</p><p>to a road, the high coronene concentrations cannot be</p><p>explained by contamination from motor vehicle emissions</p><p>since the particle concentration during the bush fire was</p><p>very much larger than normal and the concentration of</p><p>lead, which is an additive to gasoline in Australia, was very</p><p>low in the collected samples. Particularly large amounts</p><p>of BaP were also found in the bush-fire sample with con-</p><p>centrations of 194 pg/g compared with other collections,</p><p>which varied from 2.2 pg/g for paper incineration to 71</p><p>pg/g for the backyard burn. High concentrations of BaP</p><p>seem to arise from low-temperature combustion. The</p><p>emissions from bush fires is compatible with this inter-</p><p>pretation since the intensity of a fire can vary enormously,</p><p>and although peak temperatures in a bush fire are very</p><p>high, much of the combustion takes place at lower tem-</p><p>peratures.</p><p>The concentrations found in this study are very much</p><p>less variable than those reported by Cooke et al. (13). The</p><p>correlation coefficients, estimated similarly to those in</p><p>Table I1 for the emissions reported by Cooke et al., ranged</p><p>from -0.045 to 0.885 and averaged 0.399. The results both</p><p>in terms of concentrations and variability are, however,</p><p>much more consistent with ambient concentrations re-</p><p>ported by Sexton et al. (4 ) for Warterbury, VT, where</p><p>between 46 and 73% of the particles arose from residential</p><p>wood combustion. The major difference is that the relative</p><p>concentrations of BaP reported in the present paper are</p><p>higher by about a factor of 2.5 than those found by Sexton</p><p>et al. Relative</p><p>concentrations of BghiP and COR may also</p><p>be somewhat lower than those reported for ambient sam-</p><p>ples by Sexton et al., which is consistent with a small input</p><p>from vehicles in the ambient samples, but the difference</p><p>is not statistically significant.</p><p>(1) Degradation of PAHs. Accurate source reconcil-</p><p>iation requires that the relative amounts of PAHs do not</p><p>change markedly between emission and analysis. Changes</p><p>can occur through reactions in the atmosphere prior to</p><p>collection, or through reactions on the filter or if the</p><p>collection efficiencies are not equal for all the PAHs, as</p><p>could occur if the more volatile components were removed</p><p>from the filter.</p><p>Measurements made in the present study showed that</p><p>while up to 50% of PHE and ANT could be lost from the</p><p>filter, due to volatilization, during a 24-h sampling period</p><p>losses of the other PAHs were very much less. There was</p><p>no evidence of loss due to reactions occurring between</p><p>gases in the air and the filtered material a t the concen-</p><p>trations of ozone, nitrogen dioxide, or sulfur dioxide that</p><p>occur in Sydney air. This observation is consistent with</p><p>those of Grosjean et al. (14). To minimize errors arising</p><p>from the loss of the more volatile compounds, concentra-</p><p>tions of PHE, ANT, FLU, and PYR were not used in the</p><p>source reconciliation procedure.</p><p>PAHs bound to particles can be transported large dis-</p><p>tances although most of the particles collected in the urban</p><p>environment will originate from nearby sources. Korf-</p><p>macher et al. (15) have shown that PAHs adsorbed on fly</p><p>ash are much less susceptible to photolysis than the pure</p><p>compounds. Lunde and Bjorseth (16) have shown that</p><p>PAHs generated in the United Kingdom can be trans-</p><p>ported to Southern Norway without major degradation.</p><p>On the other hand, Kamens et al. (17, 18) showed that</p><p>rapid photolytic degradation of PAHs on wood soot can</p><p>occur with reaction half-times of less than an hour. This</p><p>would not necessarily lead to much change in the product</p><p>spectrum, however, since the removal half-times were very</p><p>similar for most of the PAHs.</p><p>If photolytic decomposition of PAHs leads to a change</p><p>in the relative amounts of each of the PAHs present there</p><p>1583 Environ. Sci. Technol., Vol. 24, NO. 10, 1990</p><p>Table 111. Relative Concentrationsa of PAHs as a Function of Time of Day</p><p>time of day</p><p>PAH 4-6 6-8 8-10 10-12 12-14 14-16 16-18 18-20</p><p>PHE 1.66 1.25 1.26 1.82 2.21 2.47 1.76 2.66</p><p>ANT 0.02 0.04 0.04 0.02 n.d. 0.04 0.04 0.05</p><p>FLU</p><p>PYR</p><p>BaA</p><p>CHR</p><p>BbF</p><p>BkF</p><p>BaP</p><p>DbA</p><p>BghiP</p><p>IP</p><p>COR</p><p>total</p><p>2.90</p><p>1.83</p><p>0.28</p><p>0.83</p><p>0.75</p><p>0.33</p><p>0.51</p><p>0.17</p><p>1.50</p><p>1.00</p><p>1.34</p><p>13.22</p><p>3.11</p><p>1.27</p><p>0.20</p><p>0.89</p><p>0.84</p><p>0.42</p><p>0.65</p><p>0.18</p><p>1.40</p><p>1.00</p><p>1.31</p><p>12.56</p><p>2.64</p><p>1.17</p><p>0.31</p><p>0.89</p><p>0.75</p><p>0.47</p><p>0.58</p><p>0.26</p><p>1.56</p><p>1.00</p><p>1.49</p><p>12.42</p><p>a All concentrations are relative to the concentration of IP.</p><p>2.38</p><p>1.71</p><p>0.24</p><p>0.82</p><p>0.78</p><p>0.47</p><p>0.53</p><p>0.20</p><p>1.49</p><p>1.00</p><p>1.20</p><p>12.67</p><p>5.75</p><p>1.32</p><p>0.21</p><p>0.64</p><p>0.89</p><p>0.36</p><p>0.50</p><p>0.29</p><p>1.04</p><p>1.00</p><p>1.21</p><p>15.43</p><p>2.24</p><p>1.13</p><p>0.18</p><p>0.58</p><p>0.62</p><p>0.20</p><p>0.42</p><p>0.18</p><p>1.33</p><p>1.00</p><p>1.31</p><p>11.71</p><p>2.61</p><p>1.31</p><p>0.30</p><p>0.73</p><p>0.71</p><p>0.29</p><p>0.47</p><p>0.24</p><p>1.00</p><p>1.00</p><p>1.50</p><p>11.99</p><p>2.84</p><p>1.31</p><p>0.18</p><p>0.87</p><p>0.72</p><p>0.31</p><p>0.44</p><p>0.26</p><p>1.15</p><p>1.00</p><p>1.20</p><p>13.03</p><p>\</p><p>1:</p><p>0 DbA</p><p>0 Pb P .- - ,E PAHxlf3</p><p>1 3.0</p><p>I I I I I t I I</p><p>4 6 8 10 12 14 16 18 20</p><p>Time - ESST (h)</p><p>Figure 2. Diurnal variation in PAH and lead concentrations during</p><p>summer.</p><p>should be a change in the relative concentrations with time</p><p>of day on a sunny summer day when insolation is high.</p><p>Samples of suspended particulate matter were collected</p><p>for 2-h periods from 4 a.m. until 8 p.m. on a typical sum-</p><p>mer day in January, when in fact most of the PAHs arise</p><p>from motor vehicles rather than burning of vegetation. As</p><p>indicated in Table 111, these measurements showed that</p><p>the total concentration of PAHs in the well-illuminated</p><p>period from 10 a.m. to 4 p.m. were lower by a factor of 2.0</p><p>than those observed between 4 a.m. and 10 a.m. and 4 p.m.</p><p>and 8 p.m. As indicated by Table 111, the ratio of con-</p><p>centrations of each of the PAHs to that of IP does not</p><p>seem to change throughout the day, suggesting that pho-</p><p>tochemical activity and other reactions do not have a major</p><p>effect on product ratios. Over the same period, as shown</p><p>in Figure 2, the particulate lead concentration, which arises</p><p>from the use of lead as an additive to gasoline, varied in</p><p>a similar manner to that of the PAHs.</p><p>Further evidence on the importance of atmospheric re-</p><p>actions in determining PAH concentration can be obtained</p><p>by comparing ambient concentrations in the winter months</p><p>with those in the summer months since removal of the</p><p>PAHs is likely to be more rapid at the higher temperatures</p><p>which occur in summer rather than winter. During the</p><p>period of the study the New South Wales Pollution Control</p><p>Commission (SPCC) collected high-volume air samples,</p><p>which were analyzed for lead (19) at a site at which we were</p><p>carrying out ambient air monitoring. As shown in Table</p><p>1584 Environ. Sci. Technol., Vol. 24, No. 10, 1990</p><p>Table I V Changes in PAH Concentration during the Year</p><p>month</p><p>January</p><p>February</p><p>March</p><p>April</p><p>May</p><p>June</p><p>July</p><p>August</p><p>September</p><p>October</p><p>November</p><p>December</p><p>pg m-3 pg m-3</p><p>0.2 22.8</p><p>0.3 24.9</p><p>0.6 33.3</p><p>0.8 49.7</p><p>1.1 81.0</p><p>1.0 85.3</p><p>0.9 64.6</p><p>0.9 35.2</p><p>0.5 35.7</p><p>0.4 44.5</p><p>0.5 30.6</p><p>0.4 22.3</p><p>lead," TSP, total PAH</p><p>ngm-3 PAH/Pb</p><p>3.56</p><p>4.25</p><p>5.72</p><p>7.79</p><p>32.2</p><p>37.5</p><p>34.2</p><p>24.3</p><p>17.3</p><p>14.9</p><p>7.30</p><p>3.69</p><p>0.018</p><p>0.014</p><p>0.010</p><p>0.010</p><p>0.029</p><p>0.037</p><p>0.038</p><p>0.027</p><p>0.035</p><p>0.037</p><p>0.015</p><p>0.009</p><p>"Lead concentrations reported by - .JW South Wa.,s State Pol-</p><p>lution Control Commission (19).</p><p>IV, the ratio of the total concentration of PAHs to lead</p><p>was 0.017 with a standard error of 0.004 for the six warm-</p><p>temperature months (October to March) compared with</p><p>a value of 0.029 for the cooler months. Burning of vege-</p><p>tation is estimated from source reconciliation to provide</p><p>6% of the PAHs in the warmer months and 24% during</p><p>the cooler months, with motor vehicles providing the bulk</p><p>of the remainder. Since vehicular traffic is fairly uniform</p><p>throughout the year, the PAH to lead concentration ratio</p><p>suggests that in the warmer months about 28 f 8% of the</p><p>PAHs could be removed from the air before collection.</p><p>This estimate is reasonably consistent with changes in the</p><p>PAH to lead ratio that were measured during the day in</p><p>summer.</p><p>The small amount of removal of PAHs that appears to</p><p>have occurred is not inconsistent with the reaction half-</p><p>times of less than an hour that have been reported for</p><p>photolytic destruction of PAHs. Hanna (20) has shown</p><p>that in a city ambient concentrations of primary pollutants</p><p>are determined largely by sources within a few kilometers,</p><p>even for unreactive pollutants.</p><p>(2). Impact of Vegetative Combustion on Atmos-</p><p>pheric PAH Levels. The contribution of PAHs derived</p><p>from combustion of vegetation depends very much on the</p><p>season. PAHs resulting from the burning of vegetation</p><p>normally make a small minor contribution to the ambient</p><p>concentration in summer but provide about 30% of the</p><p>PAHs during winter. This pattern can be distributed by</p><p>major events such as bush fires. As shown in Figure 3, a</p><p>bush fire 50 km distant from the sampling site greatly</p><p>affected suburban air by producing high concentrations</p><p>Relative mnc. Of PAH</p><p>l2 r</p><p>8 /I</p><p>0 summer profile</p><p>I Winferpmlile</p><p>?zz Bushlire influence on Summer plolile</p><p>0 Bushlire</p><p>Backvard Burn</p><p>4</p><p>2</p><p>0</p><p>FLU PVR Ban CHR BbF BkF BaP ObA BghiP IP COR</p><p>Flgure 3. Typical profiles of PAHs in amblent air.</p><p>of total suspended particulates (TSP) as well as elevating</p><p>the PAH burden, in particular for BaP, but also for FLU,</p><p>PYR, CHR, and DbA both absolutely and relative to IP.</p><p>This sample, which was collected during summer, can be</p><p>compared with the more typical summertime collection,</p><p>which is also shown. In Sydney, elevated concentrations</p><p>of particulate matter from bush fires often occur for 3 or</p><p>more days. One hush fire, therefore, could</p><p>conceivably give</p><p>rise to 5% of the total exposure to BaP over the course</p><p>of 1 year.</p><p>A normal suburban collection, unaffected by bush fires</p><p>or local combustion sources, has a large motor vehicle</p><p>component, as indicated by significant contributions of</p><p>BghiP and COR to the overall PAH profile. In wood</p><p>burns, however, the concentrations of these PAHs relative</p><p>to IP are smaller but those of FLU, PYR, BaP and DbA</p><p>are much greater. During winter, wood is burnt for do-</p><p>mestic purposes, which results in elevating the total at-</p><p>mospheric PAH burden and particularly the concentration</p><p>of BaP. This can be seen in Figure 3, which shows typical</p><p>summer and winter profiles.</p><p>In Sydney atmospheric concentrations increase during</p><p>the cooler months, not only because of the additional</p><p>sources, but also because of a combination of meteoro-</p><p>logical conditions, such as strong radiation inversions</p><p>during the night, which effectively trap low-level emissions</p><p>close to the ground and also low wind speeds occurring</p><p>during drainage flow along the river valleys. The shorter</p><p>daylight hours and reduced temperatures would also retard</p><p>volatilization and chemical destruction of PAHs. A com-</p><p>bination of these factors therefore produces higher con-</p><p>centrations of all PAHs and in particular BaP.</p><p>Conclusion</p><p>With the exception of those resulting from bush fires,</p><p>profiles of polycyclic aromatic hydrocarbons arising from</p><p>the combustion of nonfossil fuel material, which are likely</p><p>to be significant sources of particulate matter in Sydney,</p><p>are very similar to each other but different from profiles</p><p>arising from combustion of fossil fuels in motor vehicles.</p><p>Bush fires lead to high concentrations of benzo[a]pyrene</p><p>and also corouene, which is often used as an indicator of</p><p>polycyclic aromatic hydrocarbons derived from gasoline-</p><p>fueled motor vehicles. Bush fires, which are common in</p><p>the Sydney region during summer, could contribute very</p><p>significantly to exposure of the population to polycyclic</p><p>aromatic hydrocarbons in general and benzo[a]pyrene in</p><p>particular.</p><p>Registry No. COR, 191-07-1; FLU, 206-44-0; PYR, 129-00-0;</p><p>BaA, 56-55-3; CHR, 21801-9; BbF, 205-99-2; BkF, 207-08-9; BaP,</p><p>50-32-8; DbA, 53-70-3; BghiP, 191-24-2; IP, 193-39-5.</p><p>Literature Cited</p><p>(1) Pott, P. Chirurgical Obseruations; Hawes, Clarke and</p><p>Cullings: London, 1775.</p><p>(2) International Agency for Research on Cancer. Polynuclear</p><p>Aromatic ComDounds Part 1: IARC MonoeraDhs on the</p><p>Evaluation of <he Carcinogenic Risk of Cheki& to Hu-</p><p>mans, Vol32; IARC Lyon, France, 1983.</p><p>(3) Ramdahl, T.: Alfheim, I.: Rustad. S.: Olsen. T. Chemosphere</p><p>1982, I I, 601-611.</p><p>(4) Sexton, K.; Liu, K.-S.; Hayward, S. B.; Spengler, J. D.</p><p>Atmos. Enuiron. 1985,19, 1225-1236.</p><p>(5) Greenberg, A.; Darack, F.; Harkov, R.; Lioy, P.; Daisey, J.</p><p>Atmos. Enuiron. 1985, 19, 1325-1339.</p><p>(6) Harkov, R.; Greenberg, A. J. Air Pollut. Control Assoc. 1985,</p><p>35,23&243.</p><p>(7) Australian Bureau of Statistics. Cataloe No. 8212.0. 1987.</p><p>Court, J. D.; Goldeack, R.; Fer& L. M.;Plack, M. A.'Clean</p><p>Air 1981, 15, 6 1 2 .</p><p>Gamlin, L.; Price, B. New Sci. 1988, 1637, 4&51.</p><p>Williams, D. J., CSIRO, personal communication, 1987.</p><p>Milne, J. W.; Roberts, D. B.; Walker, S. J.; Williams, D. J.</p><p>In The Urban AtmosphereSydney a Case Study; Carras,</p><p>J. N.. Johnson G. M.. Eds.: CSIRO Melbourne. Australia.</p><p>19831 pp 181-197.</p><p>(12) Gordon, R. J.; Bryan, R. J. Enuiron. Sci. Technol. 1973,</p><p>(14)</p><p>(15)</p><p>7, 1050-1053.</p><p>Cooke, W. M.; Allen, J. M.; Hall, R. E. In Residential Solid</p><p>Fueb: Enuironmental Impacts and Solutions; Cooper, J.</p><p>A,, Malik, D., Eds.; Oregon Graduate Center Publications:</p><p>Beaverton. OR. 1982: no 139-163.</p><p>Grosjean, D.; F&, K::'Hmison, J. Enuiron. Sei. Technol.</p><p>1983, 17, 673-679.</p><p>Korfmacher, W. k; Wehry, E. L.; Mamantov, G.; Natusch,</p><p>D. F. S. Enuiron. Sci. Technol. 1980,14, 1094-1099.</p><p>Lunde, G.; Bjorseth, A. Nature 1977,268, 518519.</p><p>Kamens, R. M.: Perry, J. M.; Saucy, D. A,; Bell, D. A,;</p><p>Newton, D. L.; Brand, B. Environ. Int. 1985,I1,131-136.</p><p>Kamens, R. M.; Fulcher, J. N.; Zhisbi, G. Atmos. Enuiron.</p><p>1986,20,1579-1587.</p><p>New South Wales State Pollution Control Commission. Air</p><p>Qualitv Measurements in N.S.W. Annual Review 1985.</p><p>iPCC- Sydney, Australia, 1985.</p><p>Hanna, S. R. J. Air Pollut. Control Assoc. 1971,21,714-777.</p><p>Received for review May 21, 1990. Accepted June 11, 1990.</p><p>Envlron. Sci. Technol.. Vol. 24. No. 10. 1990 1585</p>