Individual Polyaromatic Hydrocarbons Research Articles

Dietary exposure to polyaromatic hydrocarbons of the Hong Kong population

Polyaromatic hydrocarbons (PAHs) are ubiquitous in the environment and food. The Joint FAO/WHO Expert Committee on Food Additives concluded 13 individual PAHs are carcinogenic and genotoxic in vitro and in vivo. Food is recognized as the main source of exposure to PAHs for adult non-smokers, which contributed to more than 90% of total exposure. In this study, 300 food samples were collected in Hong Kong, analysed the levels of 16 European Union priority PAHs, the dietary exposure to these PAHs by the local adult population from these food items, and the associated health risk. The most predominant detectable PAH was chrysene (CHR) (14.4%), followed by benzo[c]fluorene (11.2%), benzo[a]anthracene (BaA) (10.6%) and benzo[b]fluoranthene (BbFA) (7.8%). The dietary exposures for average consumers of benzo[a]pyrene (BaP) and PAH4 (sum of BaP, CHR, BaA and BbFA) were 0.13–0.90 and 1.4–4.2 ng/kg bw/day respectively for lower and upper bound approaches. Cereal and its products contributed more than 50% to BaP and PAH4 for average consumers in a lower-bound approach. The margin of exposure (MOE) approach was used to assess the health risks of consumers. The calculated MOE values for both BaP and PAH4 of the average and high consumers (90th percentile) were >50,000, indicating a low concern for the health of the Hong Kong population.

Dietary exposure to polyaromatic hydrocarbons of the Hong Kong population

Polyaromatic hydrocarbons (PAHs) are ubiquitous in the environment and food. The Joint FAO/WHO Expert Committee on Food Additives concluded 13 individual PAHs are carcinogenic and genotoxic in vitro and in vivo. Food is recognized as the main source of exposure to PAHs for adult non-smokers, which contributed to more than 90% of total exposure. In this study, 300 food samples were collected in Hong Kong, analysed the levels of 16 European Union priority PAHs, the dietary exposure to these PAHs by the local adult population from these food items, and the associated health risk. The most predominant detectable PAH was chrysene (CHR) (14.4%), followed by benzo[c]fluorene (11.2%), benzo[a]anthracene (BaA) (10.6%) and benzo[b]fluoranthene (BbFA) (7.8%). The dietary exposures for average consumers of benzo[a]pyrene (BaP) and PAH4 (sum of BaP, CHR, BaA and BbFA) were 0.13–0.90 and 1.4–4.2 ng/kg bw/day respectively for lower and upper bound approaches. Cereal and its products contributed more than 50% to BaP and PAH4 for average consumers in a lower-bound approach. The margin of exposure (MOE) approach was used to assess the health risks of consumers. The calculated MOE values for both BaP and PAH4 of the average and high consumers (90th percentile) were >50,000, indicating a low concern for the health of the Hong Kong population.

How do zeolite-templated carbons grow?

Major insights into the formation mechanism of zeolite-templated carbons (ZTCs) were achieved via a thorough ex situ kinetic study of the hybrid (carbon/zeolite) and carbon materials. In depth characterization of the chemical, electrical, textural, and morphological properties of the materials allowed us to draw a precise picture of the key steps of the ZTC formation. An in situ time resolved GC study enabled us to achieve complementary insights into the ethylene consumption and hydrogen production during ZTC synthesis. Three stages could be disclosed: nucleation, growth and condensation. During nucleation, individual polyaromatic hydrocarbons (PAHs) develop through the aromatization of ethylene. These PAHs present high spin concentration and react upon zeolite dissolution, leading to unstructured carbon particles of undefined morphology. These carbons feature persistent radicals. During growth, the PAHs evolve to form more complex rylene-type molecules. Typical structural, textural, and morphological features of ZTCs start to emerge during this second stage. The evolution of electrical conductivity of hybrid materials indicates partial condensation of PAHs throughout the zeolite crystals leading to their connection. The carbon materials achieved during the second stage can be described as composites of ZTCs and randomly reacted PAHs. Condensation, which is importantly induced by heat treatment, triggers full connection of the ZTC network. Textural, morphological, structural, and electrical features develop, which result directly from zeolite templating. Final ZTCs feature carbonyl functionalization, which is inherent to the zeolite dissolution step and probably results from radical quenching with water.

Bacteria and fungi mediated degradation of poly aromatic hydrocarbons and effect of surfactant Tween-80

ABSTRACT Microorganisms (17 bacteria and 3 fungi) isolated from crude oil-contaminated soils were evaluated for degradation of five polyaromatic hydrocarbons (PAHs), both in the absence (-T80) and the presence of surfactant Tween-80 (+T80) at a 10 mg L−1 concentration of each PAH. Results of the heat map and Tukey HSD revealed that highest PAH degradation was observed by Kocuria rosea in +T80 treatment. Degradation (%) of individual PAH (-T80, +T80) was naphthalene: 96.6, 98.9; fluorene: 93.8, 95.1; phenanthrene: 58.1, 70.9; anthracene: 19.9, 32.5 and pyrene: 13.8, 54.7, respectively. Tukey HSD further revealed that all three fungi Trichoderma atroviride, Aspergillus nidulans and Aspergillus sydowii showed almost similar degradation of selected PAH. Based on degradation ability, consortia of K. rosea and A. sydowii were used for PAH degradation at 10, 50 and 100 mg L−1 in the presence of Tween-80. Results suggested that PAH degradation slowed down with the increase in the concentration. PAH degradation products phthalic acid and anthrone or phenanthrene-9,10 oxide or 9-phenanthrol were identified as a product of degradation. Bacterial strain Arthrobacter pascens, Pseudomonas aeruginosa, Bacillus megaterium, Bacillus sp., Bacillus niacini and Bacillus siamensis showed high fluorescence diacetate (FDA) hydrolase activity, whilst A. pascens, K. rosea, Pseudomonas sp. and B. niacini showed a significant soluble protein content.

Synthesis of highly efficient asphalt-based carbon for adsorption of polycyclic aromatic hydrocarbons and diesel from emulsified aqueous phase

This work reports the syntheses of an inexpensive and efficient asphalt-derived mesoporous carbon (AdMC) as an adsorbent. The adsorbent was activated with potassium hydroxide to increase its surface area and then characterized by SEM–EDS, FT-IR, and BET. The adsorption properties of AdMC were evaluated for the adsorptive removal of eleven Poly Aromatic Hydrocarbons (PAHs) and diesel from water samples. The prepared AdMC showed very high surface areas and high micropore volumes equal to 2316 m2/g and 1.2 cm3/g, respectively. Various experimental conditions influencing the adsorption capacity of eleven PAHs and diesel were investigated. At high concentrations, PAHs and diesel solubility in water is very low. Hence, samples were emulsified with a surfactant, and then maximum adsorption capacity was investigated. Adsorption profile of individual PAHs was examined using gas chromatography/mass spectrometry analysis followed by liquid–liquid extraction. Total hydrocarbon removal was studied using a total organic analyzer. Asphalt-derived mesoporous sorbent showed an extreme ability to remove PAHs and diesel (average adsorption capacity of 166 mg/g for individual PAHs and diesel (maximum capacity of 1600 mg/g). The experimental results fitted the Langmuir model with a correlation efficiency of 0.9853. The results obtained for both adsorbents also matched to pseudo-second-order kinetics, suggesting that the adsorption of PAHs and diesel is chemical, monolayer, and homogeneous process.

Effects of multi-component mixtures of polyaromatic hydrocarbons and heavy metal/loid(s) on Nrf2-antioxidant response element (ARE) pathway in ARE reporter-HepG2 cells.

Exposure to polyaromatic hydrocarbons (PAHs) and heavy metal/loid(s) has been demonstrated to induce an oxidative stress response in mammalian cells. The combined effect of PAHs and heavy metal/loid(s) on the oxidative stress response has not been reported extensively. The Nrf2 antioxidant response pathway plays an important role in cellular antioxidant defense against oxidative stress-induced cell damage. In this study, we have determined the combined effect of four PAHs (benzo[a]pyrene (B[a]P), naphthalene (Nap), phenanthrene (Phe) and pyrene (Pyr)) and three heavy metal/loid(s) (arsenic (As), cadmium (Cd) and lead (Pb)) on the Nrf2 antioxidant pathway using the ARE reporter-HepG2 cell line. The mixture study was carried out for binary, ternary, quaternary and seven-component combinations of PAHs and heavy metal/loid(s). Initially, individual dose responses for the PAHs (B[a]P, Nap, Phe and Pyr) and heavy metal/loid(s) (As, Cd and Pb), as well as their respective concentrations that induced an induction ratio of 1.5 (ECIR1.5), were determined. The luciferase assay system was used to quantify the induction of the Nrf2 antioxidant pathway. The individual dose response study showed that both PAHs and heavy metal/loid(s) activated the Nrf2 antioxidant pathway in ARE reporter-HepG2 cells. Among these chemicals, Cd was the most potent inducer, followed by B[a]P and As. Based on the individual dose response findings, PAHs and heavy metal/loid(s) were mixed at equipotent ratios using a fixed concentration ratio, and the effects of the mixtures of PAHs and heavy metal/loid(s) (binary to seven-component) on the Nrf2 antioxidant pathway were determined. The mixture effects were predicted by using the concentration addition (CA) model. Overall, the results showed that the multi-component mixtures of PAHs and heavy metal/loid(s) induced an oxidative stress response in ARE reporter-HepG2 cells, and that the CA model is an appropriate model to predict the interaction effect of these selected mixtures. A human cell line-based reporter gene assay system was successfully used to determine the mixture effects of two groups of common contaminants on oxidative stress response pathway.

Butyltins, polyaromatic hydrocarbons, organochlorine pesticides, and polychlorinated biphenyls in sediments and bivalve mollusks in a mid-latitude environment from the Patagonian coastal zone.

Butyltins (BTs), polyaromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), and polychlorinated biphenyls (PCBs) were assessed in a mid-latitude environment of the Patagonian coast, distant from significant pollutant sources. Bioaccumulation processes through bottom sediment resuspension were suggested by BTs level (expressed as ng of tin [Sn] g(-1) dry wt) found in surface sediment (<limit of detection [LOD]-166.5 ng [Sn] g(-1) dry wt) and bivalve mollusks (29.4-206.0 ng [Sn] g(-1) dry wt); whereas imposex incidence was only 15% in the gastropod Pareuthria plumbea collected near a harbor. Low hydrocarbon pollution was found in sediments and bivalves with ∑PAHs(16) ranging from <LOD to 94.9 ng g(-1) dry weight and from <LOD to 54.9 ng g(-1) dry weight, respectively. Values were typical of locations distant from pollutant sources and showed different compositional patterns for both substrates. However, concentrations for some individual PAHs in sediments were found over the threshold effect level. On average, ΣPCB did not exceed the sediment quality guidelines being 0.57 ± 0.88 ng g(-1) dry weight in sediments and 0.41 ± 0.26 ng g(-1) dry weight in bivalves. Average ΣOCPs in sediments were 0.53 ± 0.34 ng g(-1) dry weight and ranged from <LOD to 0.22 ng g(-1) dry weight in bivalves, showing a different pattern and suggesting a different accumulation pathway as was found for PAHs. Although both discrete and atmospheric sources can be considered for PAHs, organochlorines pollution was clearly related to atmospheric global transport, indicating that in the studied area, OCPs and PCBs experience permanent or temporal deposition during their migration to southern zones.

Evaluation of the levels of reactive di-carbonyl compounds and polyaromatic hydrocarbons in processed Atlantic horse mackerel (Trachurus trachurus)

Trachurus trachurus (locally called kote in Western Nigeria) is a table fish. During processing like poaching and smoking, fish come in contact with water, smoke and high temperatures, which may interfere with the nutrient contents and are potential sources of reactive di-carbonyl compounds (RDCs) and polyaromatic hydrocarbons (PAHs). This study was therefore conducted to determine the level of RDCs and PAHs in raw and processed Trachurus trachurus fillet; skin, head and bones (SHB). Fish samples were prepared by poaching and smoking (charcoal and wood). RDCs and levels of 5 individual PAHs including fluorene, phenanthrene, anthracene, benz(a)anthracene and naphthalene were determined in raw, poached and smoked (charcoal and wood) Trachurus trachurus using standard methods. Results indicated that all processing methods significantly increased (p < 0.05) levels of RDCs and PAHs in the fillet and SHB. In conclusion, the study demonstrated that charcoal smoke processing produced the lowest levels of RDCs and PAHs in kote fillet and SHB.

Toxic equivalency factor and statically analysis of carcinogenic micro air pollutants in urban soil at the northern part of India

The objective of the present study was to ascertain contamination levels of soils with micro air pollutants (MAPs), toxic equivalency factor and statically analysis of carcinogenic MAPs, distribution behavior and human exposure during summer and winter round the year. The average MAP concentration were found to be 18.99 and 4.94, whereas concentration of 16 individual MAPs were found to vary between 0.03 and 199.23 μg/g and 0.009 and 29.4 μg/g, during summer and winter seasons, respectively. The average concentration of carcinogenic and low carcinogenic MAPs during summer and winter were found to be 5.2 and 31.20, 2.2 and 6.5, 4.75 respectively. The average ratio of low carcinogenic to carcinogenic MAPs was found to be 1:6 during summer and 1:3 during winter at most of the intercepts. It was also observed that five-ringed MAPs were in higher concentration than two-ringed MAPs in almost two seasons at most of the intercepts. Dib(a,h)A and B(a)P were the two individual polyaromatic hydrocarbons found in the highest concentration at almost all the intercepts in two seasons. It was also observed that the total potential carcinogenic MAP concentration was quite high (86%) in comparison to low carcinogenic MAPs (16%) at most of the intercepts within the city round the year.

Bioremediation of a tropical clay soil contaminated with diesel oil

The removal of polyaromatic hydrocarbons (PAH) in tropical clay soil contaminated with diesel oil was evaluated. Three bioremediation treatments were used: landfarming (LF), biostimulation (BS) and biostimulation with bioaugmentation (BSBA). The treatment removal efficiency for the total PAHs differed from the efficiencies for the removal of individual PAH compounds. In the case of total PAHs, the removal values obtained at the end of the 129-day experimental period were 87%, 89% and 87% for LF, BS and BSBA, respectively. Thus, the efficiency was not improved by the addition of nutrients and microorganisms. Typically, two distinct phases were observed. A higher removal rate occurred in the first 17 days (P-I) and a lower rate occurred in the last 112 days (P-II). In phase P-I, the zero-order kinetic parameter (μg PAH g−1 soil d−1) values were similar (about 4.6) for all the three treatments. In P-II, values were also similar but much lower (about 0.14). P-I was characterized by a sharp pH decrease to less than 5.0 for the BS and BSBA treatments, while the pH remained near 6.5 for LF. Concerning the 16 individual priority PAH compounds, the results varied depending on the bioremediation treatment used and on the PAH species of interest. In general, compounds with fewer aromatic rings were better removed by BS or BSBA, while those with 4 or more rings were most effectively removed by LF. The biphasic removal behavior was observed only for some compounds. In the case of naphthalene, pyrene, chrysene, benzo[k]fluoranthene and benzo[a]pyrene, removal occurred mostly in the P-I phase. Therefore, the best degradation process for total or individual PAHs should be selected considering the target compounds and the local conditions, such as native microbiota and soil type.

Evaluation of surface sediment contamination by polycyclic aromatic hydrocarbons in colony Z3—(Patos Lagoon, Brazil)

This paper describes the extraction and analysis of Polyaromatic Hydrocarbons (PAHs) in five points of the Patos Lagoon Estuary. These points were in the area named “colony Z3”, which is a craft fishermen community in Pelotas City (southern Brazil). Samples were collected in July of 2007, and the concentrations of 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs) were determined by gas chromatography coupled to a mass spectrometry detector (GC/MS). The PAH concentrations ranged from 4.7 to 112.5 µg kg − 1 dry weight. Sediment samples with the highest PAH concentrations appeared at point 2, which is a pier. The correlation between the total organic material (TOM) and the total PAH concentration suggests that TOM plays an important role in controlling the PAH levels in sediments. According to the observed ratios of individual PAHs, the contamination in the studied areas originated both from high-temperature pyrolytic processes and petrogenic sources. The levels of PAHs at the studied sites in the Z3 colony (Patos Lagoon) were low enough that they should not exert adverse biological effects.

Assaying Baseline Status of Particulate Laden Polyaromatic Hydrocarbon for a Grass Root Level Industrial Project

A study of particulate laden polyaromatic hydrocarbon was conducted at 13 selected locations in a 10 km radial distance of a proposed site for a grass root level industry. Suspended particulate matter samples were continuously monitored for 24 h over a period of 3 months. The Polyaromatic Hydrocarbons (PAHs) were extracted from the particulate samples and analysed using Gas Chromatograph-Mass Spectrometer. Limit of Quantification was also established for individual PAHs. Coal combustion and traffic emission were the major contributors for PAHs in the region. The relative contribution of 2, 3, 4, 5, and 6 ring PAHs in particulates of different sampling sites was also investigated and it is observed that 4 ring (29.76%) and 5 ring (29.06%) compounds are prominent in the particulates measured in the region.

Charcoal emissions as a source of CO and carcinogenic PAH in mainstream narghile waterpipe smoke

Burning charcoal is normally placed atop the tobacco to smoke the narghile waterpipe. We investigated the importance of charcoal as a toxicant source in the mainstream smoke, with particular attention to two well-known charcoal emissions: carbon monoxide (CO) and polyaromatic hydrocarbons (PAH). CO and PAH yields were compared when a waterpipe was machine smoked using charcoal and using an electrical heating element. The electrical heating element was designed to produce spatial and temporal temperature distributions similar to those measured using charcoal. With a popular type of ma’ assel tobacco mixture, and using a smoking regimen consisting of 105 puffs of 530 ml volume spaced 17 s apart, it was found that approximately 90% of the CO and 75–92% of the 4- and 5-membered ring PAH compounds originated in the charcoal. Greater than 95% of the benzo( a)pyrene in the smoke was attributable to the charcoal. It was also found that the relative proportions of individual PAH species, the “PAH fingerprint”, of the mainstream smoke were highly correlated to those extracted from the unburned charcoal ( R 2 > 0.94). In contrast, there was no correlation between the PAH fingerprint of the electrically heated and charcoal-heated conditions ( R 2 < 0.02). In addition to inhaling toxicants transferred from the tobacco, such as nicotine, “tar”, and nitrosamines, waterpipe smokers thus also inhale large quantities of combustion-generated toxicants. This explains why, despite the generally low temperatures attained in the narghile tobacco, large quantities of CO and PAH have been found in the smoke.

Toxic effects of some major polyaromatic hydrocarbons found in crude oil and aquatic sediments on Scenedesmus subspicatus

The green alga, Scenedesmus subspicatus was exposed for 7 days to a series of PAHs (polyaromatic hydrocarbons) of increased molecular weight from two to five rings [naphthalene (Nap), anthracene (Ant), phenanthrene (Phe), pyrene (Pyr) and benzo(a)pyrene (BaP)]. The toxicity measured as population growth inhibition by individual PAH to the S. subspicatus followed the order: BaP>Pyr>Ant>Phe>Nap. These results confirmed that the toxicity potential of PAHs seems to be strongly influenced by their physico-chemical properties (aqueous solubility, K ow, coefficient of volatilization, etc.) and the conditions of algae culture (light, presence of nitrate ions, etc.). Consequently, Nap, Phe and Ant having low K ow values and low coefficient of volatilization values were less toxic than BaP with the highest k ow value, indicating for example why Nap with the lowest EC 50 value was nearly 2×10 5 times lower than that of BaP. Moreover, nitrate ions seemed to act directly on the degree of hydroxylated radical reactivity of PAHs, since BaP always remained the most toxic of the compounds tested. The results were also agreed with the QSAR model for toxicity prediction of PAHs to many aquatic organisms.

Fate of polyaromatic hydrocarbons in the pyrolysis of industrial waste oils

Four different waste oils have been pyrolyzed using an experimental bench scale pyrolysis unit at 600 °C under atmospheric pressure and the polyaromatic hydrocarbons (PAHs) have been analyzed in the valuable liquid fraction. After the appropriate digestion and extraction procedures, the individual PAHs were quantified in each case by HPLC–UV. Toxicity of the PAHs mixture obtained in the liquid fraction resulting from the pyrolysis of machine waste oil, automotive waste oil, hydraulic waste oil and cutting waste oil as well as the PAHs profile are compared and discussed.

Natural attenuation/phytoremediation in the vadose zone of a former industrial sludge basin.

The natural attenuation of polyaromatic hydrocarbons (PAHs) in the vadose zone of a naturally revegetated former industrial sludge basin (0.45 ha) was examined. This was accomplished by comparing the concentration of 16 PAH contaminants present in sludge collected below the root zone of plants with contaminants present at 3 shallower depths within the root zone. Chemical analysis of 240 samples from 60 cores showed the average concentration of total and individual PAHs in the 0-30 cm, 30-60 cm, and bottom of the root zone strata were approximately 10, 20, and 50%, respectively, of the 16, 800 ppm average total PAH concentration in deep non-rooted sludge. Statistically significant differences in average PAH concentrations were observed between each strata studied and the non-rooted sludge except for the concentrations of acenaphthene and chrysene present at the bottom of the root zone in comparison to sludge values. The rooting depth of the vegetation growing in the basin was dependent on both vegetation type and plant age. Average rooting depths for trees, forbs (herbaceous non-grasses), and grasses were 90, 60, and 50 cm, respectively. The deepest root systems observed (100-120 cm) were associated with the oldest (12-14 year-old) mulberry trees. Examination of root systems and PAH concentrations at numerous locations and depths within the basin indicated that plant roots and their microbially active rhizospheres fostered PAH disappearance; including water insoluble, low volatility compounds, i.e. benzo(a)pyrene and benzo(ghi)perylene. The reduced concentration of PAHs in the upper strata of this revegetated former sludge basin indicated that natural attenuation had occurred. This observation supports the concept that through appropriate planting and management practices (phytoremediation) it will be possible to accelerate, maximize, and sustain natural processes, whereby even the most recalcitrant PAH contaminants (i.e. benzo(a)pyrene) can be remediated over time.

Conductance calculations through stacks of polyaromatic hydrocarbons

Polyaromatic hydrocarbons (PAH) can be synthesized in many different sizes. They form self-assembled stacks of molecules which could be utilized in nanoelectronics applications. In this work we study stacks of PAH contacted to multichannel metallic leads. The conductance is calculated using the Landauer formula for the neutral and alkali doped stacks of PAH. We show that in the non-resonance tunneling limit the conductance is linearly related to the size of the individual PAH. A simple expression is shown to approximately describe the dependence of the conductance on the number of molecules in a stack as well as the inter-molecular interaction.

Phytoremediation of Soils Contaminated with Wood Preservatives: Greenhouse and Field Evaluations

ABSTRACT Phytoremediation was evaluated as a potential treatment for the creosote-contaminated surface soil at the McCormick and Baxter (M&B) Superfund Site in Portland, Oregon. Soil at the M&B site is contaminated with pentachlorophenol (PCP) and polyaromatic hydrocarbons (PAHs). Eight individual PAH compounds (containing four to six aromatic rings) were included in the investigation. Greenhouse and field studies were carried out using perennial ryegrass (Lolium perenne). The following three treatments were compared in both studies: T1 = planted-amended soil; T2 = unplanted-amended soil; and T3 = unplanted-unamended soil. The amendments were mineral nutrients and dolomite, which was used to raise the acidic pH of the soil. Contaminant concentrations in the soil were measured initially and at regular intervals for several months. In the greenhouse study, the concentrations of certain contaminants decreased as a function of time. Thus, PCP, fluoranthene, pyrene, chrysene, and benzo(k)fluoranthene appeared to undergo biodegradation in all of the treatments. On the other hand, certain larger molecular weight PAHs were relatively recalcitrant. These “recalcitrant PAHs” included benzo(b)fluoranthene, benzo(a)pyrene, benzo(g,h,i)perylene and indeno(1,2,3-cd)pyrene. Statistical methods were used to compare the concentrations of the more easily biodegraded contaminants in treatments T1, T2, and T3. The statistical analysis was facilitated by normalizing the contaminant concentrations relative to the sum of the recalcitrant PAHs in the same sample. Thus, ratios were created that could be compared directly to benchmark values indicative of the contaminant at the beginning of the study. In the greenhouse study, statistically significant differences between T1 and T2, across all treatment times, were obtained for fluoranthene, pyrene, and chrysene (p ≤0.05), suggesting enhanced rhizosphere biodegradation for these compounds. Significant differences between T2 and T3 were obtained for pyrene (p ≤0.03), indicating that nutrients stimulated the biodegradation of this contaminant. Although the greenhouse study was carried out with a well-mixed soil sample from the M&B site, an extremely uneven distribution of contaminants was encountered in the field study. The resulting scatter in the field data made comparisons difficult, and treatment-specific effects observed in the greenhouse study were not statistically significant in the field study. However, analysis of the normalized data from the field revealed the same time-dependent decreases in contaminant concentration as observed in the greenhouse study.

PAH source fingerprints for coke ovens, diesel and, gasoline engines, highway tunnels, and wood combustion emissions

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(1,2,3- cd)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 PM10. 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. The source fingerprints have been developed for use in chemical mass balance receptor modeling calculations.

Determination of Polyaromatic Hydrocarbons in the Gas Phase of Air

Polyaromatic hydrocarbons (PAH) were isolated from the gas phase of air by sorption on the Separon CHN polymeric sorbent and quantitated by capillary gas chromatography using flame ionization detection. The conditions for PAH desorption from the sorbent were examined. Hexane, giving desorption recoveries of 90-100%, was the most efficient eluent. The recovery was found independent of the amount of PAH sorbed over a wide region. Analyte losses associated with the removal of eluent were investigated. Based on the experimental results, a procedure was developed for the determination of PAH in the gaseous phase of air and tested on field samples. When 5 m3 volumes of air are sampled, the limits of determination of the individual PAH are from 10 to 20 ng/m3.