Individual Polynuclear Aromatic Hydrocarbons Research Articles

Airborne Polycyclic Aromatic Hydrocarbons in Suspended Particulates from the Urban Atmosphere of Rijeka, Croatia

Besides earlier occasional campaigns, the systematic measurements of polynuclear aromatic hydrocarbons (PAHs) in total suspended particulates (TSP) started only in 2001, while in 2006 the analyses were switched to PAHs in PM10. The annual concentrations of PAHs are following the general declining trend with other combustion pollutants as SO2. Although PM10 formed approximately 44% of TSP for the 2006 year and multi-year periods (2001–2005 and 2007–2010), the fraction of PAHs in PM10 /TSP ratio was in the range between 17% for Phe to 80% to BbF + BkF (66% for BaP). The winter to summer ratio (W/S) of individual PAH concentration is almost doubled in TSP (range: 5.2 for Phe to 21.2 for BaP) relative to PM10 (range: 2.7 for Phe to 13.5 for BaP). PAHs profiles indicate diesel vehicles as principal sources of PAHs, with the occasional contribution of metal smelters and wood combustion in winter.

Navigation Activities Assessment on the Variations of Polynuclear Aromatic Hydrocarbons, River Nile, Egypt

The River Nile is considered the most important sources of fresh water for Egypt, supplying all agricultural, cultural needs (drinking water and other civilization uses), industry, and river navigation for transport and tourism ships and boat. Polynuclear aromatic hydrocarbons (PAHs) compounds are considered an important class of hazardous environmental contaminants because some exhibit carcinogenic or mutagenic properties. PAHs can be divided according to the number of rings into low and high molecular weights PAHs. The low molecular weights consist of two and three aromatic rings (LPAHs). While the high molecular weight consists of tetra-, penta and hexa- aromatic rings (HPAHs). Four to six ring PAHs is highly mutagenic and carcinogenic while two or three ring PAHs are less mutagenic but can be highly toxic. The concentrations of PAHs in the river water at the area of El-Qanater El-Khairiya and El-Waraq was determined in order to assess the anthropogenic chemical inputs from navigation activities of; touistic ships sailing and passenger transportation as well as to assess the weathering effect on the PAHs concentrations. Water samples were selected from ten sites from the main River Nile, Dameitta Branch, Rosetta Branch, El-Rahyaha El-Nassery, and El-Rahyaha El-Menofy in October 2010. Quantification of PAHs using high performance liquid chromatography technique was carried out. Concentration and spatial distribution of individual PAHs of the reference 16 PAHs listed by the United States Environmental Protection Agency (US-EPA) were investigated in surface water of the study area. The sources of 16 PAHs (pyogenic and perterogic) were achieved using both PAHs distribution and molecular indices based on ratios of selected PAHs concentrations. Total PAHs ranged from 620- 1049 μg/l with an average of 794 μg/l. The highest value of total PAHs found in Dameitta Branch while the lowest one found in El-Rahyaha El-Nassery. The summation of LPAHs ranged from 1.3- 10.1 μg/l, while the summation of HPAHs ranged from 615- 1047 μg/l. The contamination in the study area was shown to be either pyrogenic or mixed pyrogenic and petrogenic. It was found that the PAHs in the study area were mainly derived from combustion coming from the traffics, heating system and run off. Meanwhile, the sources of pollution include petroleum-derived hydrocarbons which contributed to minor inputs. The obtained values can be considered to possess serious health hazards to both human health and all living organisms.

Distribution and sources of polynuclear aromatic hydrocarbons in Mangrove surficial sediments of Deep Bay, China

Twelve sediment samples collected from three transects of mangrove swamp of Deep Bay, Shenzhen, China, were determined for polynuclear aromatic hydrocarbons (PAHs). The total PAHs concentrations ranged from 237 to 726 ng g −1 dry weight, and showed strong correlation with total organic carbon (TOC), clay content and Pb concentrations. The highest PAHs concentrations were found in the samples from mangrove sediments. Overall, PAHs in Deep Bay sediment were lower than those in other developed areas. The biological effect due to PAHs alone in Deep Bay is expected to be low, based on the comparisons of individual and total PAHs concentrations determined in the sediment with those in USEPA sediment quality guidelines. Four and five-ring compounds dominated the PAHs composition pattern profiles. Principal component analysis (PCA) was applied to further investigate the source of PAHs. The PAH sources of Deep Bay mangrove swamp were suggested to be primarily combustion of fossil fuel, especially leaded-gasoline exhaust.

Concentrations of Some Lipophilic Chemicals in Fresh Water May Be Underestimated by Conventional Dichloromethane Extraction

Abstract A re-analysis of water samples collected to determine the occurrence of lipophilic organochlorine chemicals, total polychlorinated biphenyls (PCBs) and polynuclear aromatic hydrocarbons (PAHs) in six tributaries to Lake Ontario in 1997 to 1998 has shown relatively high concentrations of some of those chemicals in extracts of chromic acid-digested water after the water had been extracted at neutral pH. For organochlorine chemicals and PCBs the effect was dramatic—for some tributaries the sums of concentrations of the chemicals in the acidic extracts over all sampling dates were larger than the sums of concentrations of the chemicals in the (neutral) water plus suspended solids fraction that had been determined previously. In addition, some chemicals were found in the acidic extracts that were not found in the prior extracts of (neutral) water plus suspended solids. Although some individual PAHs were found at relatively high concentrations in the acidic extracts compared to extracts of (neutral) water plus suspended solids, in general the phenomenon was not significant for total PAHs. The implication of our finding is that conventional dichloromethane extraction of neutral (filtered) water and the suspended solids phases can significantly underestimate the concentrations of some lipophilic chemicals such as chlorinated hydrocarbons and PCBs in fresh water, leading to an underestimation of their loadings to aquatic ecosystems. However, it should be noted that the biological availability of chemicals that are only extractable after rigorous extraction of the water may be doubtful.

Decreased Release of PAHs from Soils as a Result of Field Bioremediation

In this study, the relationship between the release characteristics of contaminants from soil and the biodegradability of the contaminants was evaluated. The soils used were from a large-scale field site. A batch rate of release procedure was used to quantify the release of polynuclear aromatic hydrocarbons (PAHs) from manufactured gas plant site soils before and during bioremediation in a field land treatment unit (LTU). This evaluation assessed the performance of the field-scale LTU with respect to changes in the soil PAH concentrations and to changes in chemical release parameters. The practical implications of the evaluation are discussed. During 147 days of LTU operations, the concentrations of specific PAHs were reduced 39–93%. ROR studies were conducted on LTU soil samples obtained at Days 0, 58, 72, and 147 of treatment. As a result of 147 days of treatment in the LTU, the fraction of a PAH released rapidly (F) had decreased for 8 of 10 PAHs, and the value of k2 (the first-order rate constant describing slow release) had decreased for 5 of 10 PAHs. There were no increases in F or k2 for any of the PAHs as a result of treatment in the field LTU. The results indicated that (1) only a fraction of the total concentration of the individual PAHs in the LTU samples was readily available to be released from the soil; (2) the remainder was released at a much slower rate; and (3) the mass of PAH released from the LTU soils to the aqueous phase decreased considerably. In addition, the fraction of the chemical released rapidly (F) for the Day 0 soil sample provided a reasonable prediction of the extent of PAH loss during 147 days of biological treatment in the field LTU.

On the Correlation of CO and PAH Emissions from the Combustion of Pulverized Coal and Waste Tires

Results are presented on the correlation of the emissions of carbon monoxide (CO) and polynuclear aromatic hydrocarbons (PAH) from the combustion of pulverized bituminous coal and tire-derived fuel. The particle size cuts of coal and tire crumb were 63−75 and 180−212 μm, respectively. Combustion experiments were conducted in laboratory-scale facilities under controlled conditions. The relation between CO and PAH species in the combustion effluent was investigated at drop-tube furnace gas temperatures, in the range of 1000−1300 °C, and several fuel mass loadings in the furnace, expressed in terms of bulk equivalence ratios in the range of 0.7−2.4. Up to 60 two−seven ring PAH compounds were detected by capillary gas chromatography−mass spectrometry (GC−MS) techniques. Results showed that both CO and PAH emission yields increased with increasing bulk equivalence ratio (in the aforementioned range) at a fixed gas temperature. The CO and especially the PAH yields from tire-derived fuel were much higher than those from coal, but the relative amounts of individual PAH components were remarkably similar in the combustion effluent of the two fuels. At fixed bulk equivalence ratios, however, as the furnace gas temperature increased the PAH yields from both fuels decreased drastically, while the CO yields increased. At the highest temperature tested herein (1300 °C), the effluent of the combustion of both fuels was practically devoid of PAHs [at a detection limit of 0.7 μg of a PAH component/g of fuel burnt]. Reasons for the observed increase in CO with temperature are discussed. CO2 and NOx emission yields were also monitored, and the results are reported herein.

Multi-phase partitioning and co-solvent effects for polynuclear aromatic hydrocarbons (pah) in authentic petroleum- and creosote-contaminated soils

The residual oil phase, present at substantial levels in hydrocarbon-contaminated soils, was found to be the principal medium for retention of polynuclear aromatic hydrocarbons (PAH). Using authentic petroleum and creosote-contaminated soils containing 2–6% w/w solvent extractable matter, individual PAH were shown to exist in the oil phase at values between 84 and 95% w/w of the total mass of each compound in the system, with the exception of naphthalene (70% w/w). Evaluation of the phase partitioning of PAH in creosote-contaminated soil confirmed that PAH were predominantly in the creosote oil phase, with substantially lower proportions associated with soil organic matter and soil water. In the aqueous phase, solubility enhancement was observed for PAH with the degree of enhancement more evident for the hydrophobic PAH. A normalised solubility enhancement factor (ESF’) was derived to illustrate the combined effect of increased PAH solubility in the aqueous phase. Values of log ESF’ varied from −4.97 (naphthalene) to 0.09 (benzo[ghi]perylene). The findings suggest limitations exist for successful remediation of PAH contamination in the soils evaluated and indicate that the focus of remediation must be on the residual oil phase if total PAH are to be removed.

Detection of DNA-reactive metabolites in serum and their tissue distribution in mice exposed to multiple doses of carcinogen mixtures: role in human biomonitoring.

Our previous studies suggested that body fluids such as serum can serve as a novel surrogate for DNA-containing tissues to overcome the major limiting factor of tissue availability in human biomonitoring assessments. We have now examined the detectability of DNA-reactive metabolites (DRMs) in the serum and tissues of male C57BL/6 mice administered up to 10 i.p. injections on alternate days of individual polynuclear aromatic hydrocarbons (PAHs) or a mixture containing 0.01, 0.1, 1.0 and 5.0 mg/kg body wt each of benzo[a]pyrene (BP), cyclopenta[cd]pyrene (CPP) and benzo[k]fluoranthene (BF) in 200 microl sunflower oil. Four hours after the last dose, blood serum was separated and incubated with salmon testes DNA (st-DNA). 32P-Postlabeling of the st-DNA showed essentially the same adduct pattern as found in the tissue DNA, indicating that DRMs of the PAHs used were presumably sequestered and accumulated in the serum proteins. Serum DRMs were detectable at all doses tested following exposure to a mixture of BP, CPP and BF, with varying degrees of detection of the individual PAHs. At doses > or = 1 mg/kg, CPP was more potent than BP and BF in producing serum DRMs as well as tissue DNA adducts. At lower doses, however, BP was more potent. Serum DRMs were enhanced 7-20 times when the animals received 1 mg/kg each of these PAHs in the form of a mixture as compared with individual PAHs, however, tissue DNA adduction was enhanced to a lesser degree (1.5- to 2-fold). Results from these studies suggest that: (i) DNA adduction by a particular carcinogen can be significantly higher when administered in the form of a mixture than administered individually; (ii) DNA-reactive metabolites can be detected by 32P-postlabeling in the serum of animals treated with environmentally significant doses of an artificial carcinogen mixture. This approach has implications for human biomonitoring and offers an advantage because this obviates the need to acquire human tissue DNA, a major obstacle in population biomonitoring studies.

High Performance Liquid Chromatography (HPLC) of Coal Liquefaction Process Streams Using Normal-Phase Separation with Diode Array Detection

A method is described for a normal-phase separation and quantification of polynuclear aromatic hydrocarbons (PAHs) using high performance liquid chromatography (HPLC) coupled with UV-diode array detection. The method employed takes advantage of the inherent capabilities of a «charge-transfer» normal-phase HPLC column (Holstein, W. Chromatographia 1981, 14, 468), the Hypersil PAH-2 column (Keystone Scientific, Inc., Bellefonte, PA), and the ability of the diode array detector to provide UV spectra for each eluting compound having chromophores in the UV range which allows for separation, identification, and quantification in the normal phase of individual PAHs. Elaborate sample preparations, which in the past have accompanied determination and separation of individual PAHs, can be avoided for the analysis of PAHs in either extracts of natural samples or complex fuel mixtures. The potential for this method was demonstrated by the separation and quantification of five well-studied coal liquefaction process stream samples. PAHs having from two rings up to nine rings, along with their isomers and alkylated derivatives, were separated and quantified using this method. Clear differences were observed among liquefaction process streams due, in large part, to differences in feed coals and process conditions

Quantitative Evaluation of Selective Fluorescence Quenchers for Polynuclear Aromatic Hydrocarbons

In this investigation, nitromethane, nitrobenzene, and are evaluated for their class selectivity and efficiency as fluorescence quenchers of polynuclear aromatic hydrocarbons (PAHs). Conditional Stern-Volmer quenching constants are utilized for qualitative and quantitative evaluation at known quencher concentration and fluorescence excitation and emission wavelengths. From these measurements, nitromethane is determined to be the most selective quencher for alternant PAHs, 1,2,4-trimethoxybenzene is somewhat less selective for nonalternant PAHs, and nitrobenzene is an effective but nonselective quencher. The utility of this technique is demonstrated by application to a complex coal tar sample after separation of the individual PAH components by microcolumn liquid chromatography.

Incidence of adverse biological effects within ranges of chemical concentrations in marine and estuarine sediments

Matching biological and chemical data were compiled from numerous modeling, laboratory, and field studies performed in marine and estuarine sediments. Using these data, two guideline values (an effects range-low and an effects range-median) were determined for nine trace metals, total PCBs, two pesticides, 13 polynuclear aromatic hydrocarbons (PAHs), and three classes of PAHs. The two values defined concentration ranges that were: (1) rarely, (2) occasionally, or (3) frequently associated with adverse effects. The values generally agreed within a factor of 3 or less with those developed with the same methods applied to other data and to those developed with other effects-based methods. The incidence of adverse effects was quantified within each of the three concentration ranges as the number of cases in which effects were observed divided by the total number of observations. The incidence of effects increased markedly with increasing concentrations of all of the individual PAHs, the three classes of PAHs, and most of the trace metals. Relatively poor relationships were observed between the incidence of effects and the concentrations of mercury, nickel, total PCB, total DDT and p,p′-DDE. Based upon this evaluation, the approach provided reliable guidelines for use in sediment quality assessments. This method is being used as a basis for developing National sediment quality guidelines for Canada and informal, sediment quality guidelines for Florida.

Long range long term transport and decay of PAHs in a semiarid coastal area of Argentina

The transport and decay processes of environmental PAHs (Polynuclear Aromatic Hydrocarbons) are important in defining the exposures and risks which they may pose to organisms and man. In southeastern Patagonia, at about 42° S, westerly winds are very active in long range transport of top soil dust and air suspended particulate matter, a phenomenon which is similar to what occurs in other semi‐desert areas of the world. The transport of air suspended particulate around a small town at the atlantic coast of Patagonia was studied by means of a net of continuous monitors (dust gauges and high volume samplers) during 5.5 years. The sampling stations were located at various distances up to about 25 km of a single industrial source which emits PAHs as well as inorganic fluorides at about a constant, continuous and known rate. The concentration of 16 PAHs as well as inorganic F in the dust and in the air, and the rates of advective mass transport per unit of wind erosive power were recorded. The long term analysis of these variables (6‐month moving average regression models) confirms that the emission and dispersion systems have been in relative steady condition during the last years. This simple spatial and temporal situation allows the computation of average long term decay rates of several individual PAHs, by comparing the distribution and transport patterns of these compounds with that of inorganic F‐, which is used as a conservative tracer. A box model of unit angular volumes of the atmosphere centered at the emission source was fitted to the profiles of PAH and F‐concentration at increasing distance from the source. An algorithm to relate spatial rates of decay and transport with temporal rates of decay of several PAHs, based on their known emission rates at the source, is presented. Some PAHs of low molecular weight (<200) were observed to be transported more efficiently than F‐ or heavier PAHs. Environmental decay rates vary from 0.059 g/g/day (Anthracene) to ‐0.62 g/g/day (Fluoranthene), which correspond to half‐lives of 11.5 and 1.1 days respectively. The average half‐life of a group of 12 PAHs investigated is 4.33 days.

Synergistic activity of polynuclear aromatic hydrocarbon mixtures as aryl hydrocarbon (Ah) receptor agonists

The relative potencies of benzo[ a]pyrene and a complex mixture of polynuclear aromatic hydrocarbons (PAHs) produced as by-products of manufactured gas plant (MGP) residues as inducers of hepatic microsomal ethoxyresorufin O-deethylase (EROD) activity were determined in the B6C3F1 mouse. The ED 50 values for the induction response were 78 and 65 mg/kg for benzo[ a]pyrene and the MGP-PAH mixture, respectively. Analysis of the MGP-PAH mixture indicated that benzo[ a]pyrene and other compounds containing four or more rings and which are known to induce EROD activity were only present as trace components of this mixture. A comparison of the EROD induction potencies of benzo[ a]pyrene and the MGP-PAH mixture showed that the mixture was approximately 706 times more potent than expected based on its benzo[ a]pyrene content (0.17%). This induced P-450 activity could significantly increase the metabolism of the carcinogenic PAHs and thereby modulate the overall carcinogenicity of the mixture. The apparent synergistic activity of the MGP-PAH mixture was further investigated by comparing the activities of this mixture and benzo[ a]pyrene for several other aryl hydrocarbon (Ah) receptor-mediated responses including (i) induction of hepatic CYP1A1 mRNA levels, (ii) transformation of the rat cytosolic Ah receptor to a complex which binds to a dioxin responsive element, (iii) induction of EROD activity and (iv) antiestrogenicity in MCF-7 human breast cancer cells, and (v) inhibition of the splenic plaque-forming cell (PFC) response to both T cell-dependent and independent antigens in B6C3F1 mice. For the EROD and CYP1A1 mRNA induction and cytosolic transformation activities and immunosuppressive effects, the MGP-PAH mixture was approximately 100–900 times more potent as an Ah receptor agonist than expected based on its benzo[ a]pyrene content. The synergistic activity was lower (19-fold) for the antiestrogenic response in MCF-7 cells. The reason for the synergistic effects of the MGP-PAH mixture were not due to contamination of the mixture by 2,3,7,8-tetrachlorodibenzo- p-dioxin and related compounds and the results suggest that the enhanced potency of the mixture is due to unknown interactions between the individual PAHs present in the mixture.

Concentration profiles of arsenic, cadmium, chromium, copper, lead, mercury, nickel, zinc, vanadium and polynuclear aromatic hydrocarbons (PAH) in forest soil beside an urban road

A relatively busy road with a load of 3200 vehicles per day has since 1961 run through the Aplerbecker Forest near the town of Dortmund in West Germany. In October 1991 the soil in the forest (brown earth) was examined for the metals arsenic, cadmium, chromium, copper, lead, mercury, nickel, vanadium, zinc and for fifteen polynuclear aromatic hydrocarbons (EPA). It was established that — with the exception of arsenic, chromium, copper and mercury —the concentrations of all the heavy metals under investigation and of the individual PAH substances present in the forest soil decreased exponentially as the distance from the road increased. It was also established that the background concentration of the PAHs and the metals were reached after 3–5 m and 5–10 m, respectively. The concentration of lead and cadmium in the soil at the edge of the road is five times higher than that in the natural forest soil whereas chromium, nickel, vanadium and zinc show a twofold to fourfold increase in contamination. In the soil lying directly at the roadside edge, contaminations were found of up to 2 mg Cd/kg, 64 mg Cr/kg, 34 mg Cu/kg, 0.12 mg Ni/kg, 32 mg Ni/kg, 245 mg Pb/kg, 51 mg V/kg and 241 mg Zn/kg. The PAH concentrations in the road edge soil were higher by a factor of up to a 100 compared to those in the forest soil further away from the road (benzo[a]pyrene, factor 70) and were measured as follows: 22 ppm naphthalene, 6.3 ppm phenanthrene, 3.7 ppm anthracene, 32 ppm chrysene, 20 ppm benzo[a]pyrene and 43 ppm benzo[g,h,i]perylene. In this paper, the thick vegetation structure of the forest and its barrier effect on airborne hazardous substances will he discussed as a reason for the heavy accumulation of the metals and, above all, of that of the PAHs detected in the roadside soil.

Concentrations and deposition fluxes of polynuclear aromatic hydrocarbons and heavy metals in the dated sediments of a rural english lake

Deposition fluxes have been estimated from concentrations of 12 polynuclear aromatic hydrocarbons (PAHs) and six heavy metals measured in sediment cores from Esthwaite Water, a rural English lake. Atmospheric deposition is a major source of PAHs and heavy metals (Cd, Cu, Pb, and Zn) to the lake, so trends in the core may indicate the long-term record of changes in the atmospheric loading of these pollutants. The cores were dated radiometrically and pollutant trends studied since about 1820. PAH fluxes began to increase from stable background levels around the turn of the century (4.1 μg ΣPAH per gram dry weight, 287 ng ΣPAH per centimeter squared per year), rising to maximum inputs between 1950 and 1970 (42.0 μg/g, 2,954 ng/cm2 per year). The deposition flux of PAHs has decreased steadily since then and is now less than half the maximum (18.0 μg/g, 1,238 ng/cm2 per year). In recent sediments (1900-1970), the relative proportions of individual PAHs making up the ΣPAH burden have remained virtually unchanged, with fluoranthene, pyrene, and benzo[ghi]perylene the most abundant compounds. However, perylene, a biogenically produced PAH, dominates the mixture in the sediments older than 1890. Cadmium, Cu, Ni, Pb, and Zn concentrations in the Esthwaite sediments broadly follow the same temporal trends as the PAHs, with varying peak inputs between 1925 and 1975. Concentrations in the modern (surface) sediments are now lower than in recent decades, with ΣPAH, Cd, and Pb showing the greatest reduction. However, fluxes of these contaminants to surface sediments are still greater than those deposited before 1840.

The long-term persistence of polynuclear aromatic hydrocarbons (PAHs) in an agricultural soil amended with metal-contaminated sewage sludges

Polynuclear aromatic hydrocarbon (PAH) data are presented from a long-term field experiment in which soil plots were amended with single additions of sewage sludges over 20 years ago. Five sludges, each containing a different concentration of PAHs and enriched with different heavy metals (Cu, Cr, Ni or Zn), were applied to five soil plots in 1968. This increased soil PAH concentrations substantially, but by 1972 some plots had lost up to 60% of the PAHs applied. By 1989, losses had increased to about 90%. Individual PAHs have behaved differently with compound persistence a function of molecular weight. Half-lives for the compounds in soil increased from < 2 years for naphthalene to > 16 years for coronene. It is argued that biological degradation is the most important loss mechanism for PAHs in this soil. Overall, calculated half-lives are significantly longer than those previously reported under experimental conditions. The implications of this are discussed. Slower PAH degradation was observed in the plot amended with the Ni-rich sludge; by 1989, 35% of the applied PAHs was still detectable in the soil. This may be indicative of long-term heavy metal interference in microbial processes.

Chromatographic Assay of Polynuclear Aromatic Hydrocarbons in Refined Mineral Oils Applied as Dispersing Agents for Herbicides

Abstract Representative refined mineral oil samples-crude petroleum straight-run distillates-potentially used in the manufacture of crop protection products were analyzed by isocratic and gradient high-performance liquid chromatography (HPLC) to investigate their trace polynuclear aromatic hydrocarbons (PAH) content. Liquid-liquid extraction followed by size-exclusion column chromatography has been employed to isolate the fraction containing PAHs with more than two fused rings from the oils studied. The identity of individual PAHs has been confirmed by comparing the UV and fluorimetric detector signals with those of reference standards. The level of extracted PAHs in the oil samples is discussed with respect to their physical and chemical properties.

Liquid chromatographic method with fluorescence detection for the determination of polycyclic aromatic hydrocarbons in environmental samples

A method for the determination of some polynuclear aromatic hydrocarbons (PAHs) in water samples and air filters is presented. Samples were extracted with light petroleum-diethyl ether (85 + 15) and the extracts were concentrated before analysis. Reversed-phase liquid chromatography with fluorescence detection was applied to separate and determine the PAHs. Recoveries of individual PAHs from spiked water samples were 0.16–0.27 ng ml −1. Detection limits in the picogram range were obtained for each compound.

Determination of polynuclear aromatic hydro-carbons and mononitrated derivatives in air and diesel particulates

A method is described for the determination of three- to six-ring polynuclear aromatic hydro-carbons (PAHs) and mononitrated PAHs (nitro-PAHs) in particulate matter. The procedure includes Soxhlet extraction followed by fractionation using gel filtration chromatography and normal-phase liquid chromatography with an aminosilane stationary phase. The resulting fractions were separated by capillary gas chromatography (GC) into individual PAHs and nitro-PAHs which were detected by a flame-ionization detector and a thermal energy analyzer, respectively. Commercially available standards were used for quantification. Individual peak assignments were confirmed by using both mass spectral and retention index data obtained through computerized capillary GC-mass spectrometry. Several samples were processed, including a certified diesel particulate reference material supplied by the National Bureau of Standards for the purpose of evaluating analytical methods. This method may also be applicable in the determination of certain carbonyl PAHs.

Polynuclear aromatic hydrocarbons in an agricultural soil: Long-term changes in profile distribution

Soil profile samples collected from the same plot at Rothamsted Experimental Station in southeast England in 1893, 1944 and 1987 have been analysed for polynuclear aromatic hydrocarbons (PAHs). The total PAH burden of the plough layer (0–23 cm) has increased approximately four- to five-fold since the 1890s, with some compounds (notably benzo(b)fluoranthene, benzo(a)pyrene and pyrene) showing substantially greater increases. Average rates of increase in the plough layer for individual PAHs in the Rothamsted plots over the century since c. 1890 vary between 0.01 and 0.67 mg m−2 year−1. It is concluded that atmospheric deposition from natural sources has been augmented in recent years by regional fallout of anthropogenically-generated PAHs derived from the combustion of fossil fuels.The total PAH content of the 1893 Rothamsted samples was similar to that observed in soils from contemporary isolated/rural locations in the UK and showed little surface enrichment. By 1987 the surface soil at Rothamsted had been enriched in all PAH compounds measured by a factor of between 1.3 (acenaphthalene) and over 20 (benzo(a)pyrene). Increases in the PAH content of the 23–46 cm subsurface layer indicate migration of PAHs from the plough layer. Net average annual migration rates ranged from 0.01–0.14 mg m−2 year−1 for individual PAHs, and the rate appeared to be primarily a function of the plough layer PAH content, rather than physical/chemical properties of the individual compounds. This suggests particle-bound translocation as the dominant mechanism of PAH migration.