Sources Of Polycyclic Aromatic Hydrocarbons In Soils Research Articles

Content, Distribution, Source Analysis, and Risk Assessment of PAHs in Arable Soils of Taiyuan

PAHs (polycyclic aromatic hydrocarbons) accumulated in arable soils have significant impacts on farmland quality and human health, which has attracted wide attention from scientists and the public. A total of 22 arable soil samples were collected from Taiyuan, an old industrial city, including three districts (industrial zones, hilly areas, and sewage irrigation area), and the contents of 21 PAHs were detected using the GC-MS method. The sources of PAHs in soils were analyzed using the diagnostic ratios (DRs) method and positive matrix factorization (PMF) model, and the soil health risks were analyzed using the incremental lifetime cancer risk (ILCR) model. The results indicated that the average concentrations of Σ21PAHs and Σ16PAHs in arable soils of Taiyuan were 934.6 ng·g-1 and 787.7 ng·g-1, respectively, which were lower than the soil pollution risk screening value of agricultural land stipulated in GB 15168-2018. 3-5 rings PAHs were the dominant components, accounting for~90% of the Σ21PAHs. Approximately 60% of sites in industrial zones, 13% in hilly areas, and 33% in the sewage irrigation area had high PAHs contents larger than 1000 ng·g-1. The spatial distribution of PAHs showed that more severe PAHs pollution in the soil occurred in industrial areas than that in the other two districts. The DRs suggested that the combustion of coals, bio-masses, and traffic emissions were the dominant sources for PAHs pollution in arable soils in Taiyuan. The simulation results of the PMF model indicated that the sources and contribution rates of PAHs in cultivated soils were coal and biomass burning sources (59%), traffic sources (22%), and coking sources (19%). The risk assessment confirmed that the arable soils in Taiyuan had high potential carcinogenic risks; thus, more attention should be paid to the PAHs pollutions in arable soils.

An improved hybrid model on source-risk of polycyclic aromatic hydrocarbon in soils of the Yangtze River Delta urban agglomeration.

The source, exposure and risks of polycyclic aromatic hydrocarbons (PAHs) in soil environments are of great importance to evaluate soil quality. However, understanding the risks of specific sources of PAHs in soils remains poorly understood. In this study, we determined the source, exposure and risks of PAHs in the Yangtze River Delta urban agglomeration. The source analysis receptor model combined with land use types significantly increased the identification of pollution sources and improved the prediction accuracy of PAH concentrations. There is a strong correlation between the measured and predicted values of high ring PAH. The correlations of BbF, InP and Pyr are 0.947, 0.896 and 0.906 respectively, which is significantly higher than the unmodified model. By combining the ecological risk assessment and health risk assessment models of PAHs, we established an improved mixed source-risk model. The PAHs in urban soils had the highest ecological risk and health risk, with risk probabilities of 56.3 % and 28.2 %, respectively. The average contamination severity index values of PAHs caused by oil combustion sources, coal combustion sources, coking furnace sources, and fuel (biomass, petroleum, and diesel) combustion sources were 0.13, 0.10, 0.16 and 0.17, respectively. The average noncarcinogenic risks of PAHs from oil combustion sources, coal combustion sources, coking furnace sources and biomass, petroleum volatilization and diesel combustion sources to children were 0.12, 0.11, 0.08 and 0.13, respectively. Approximately half of the PAH pollution risk in forestland and grassland soil were associated with the combustion of petroleum fossil fuels. This study quantitatively analyzed the contribution of different PAHs pollution sources in different land types of soils, further calculated the risks of each pollution source to the ecological environment and human health, and proposed corresponding treatment measures, which provided scientific and systematic methods and technologies for soil pollution management in other regions of the world.

Occurrence and sources of microplastics and polycyclic aromatic hydrocarbons in surface sediments of Svalbard, Arctic.

Due to the distinct environment condition and geographic location, Svalbard has been recognized as a potential pollution reservoir in the Arctic. In this study, 8 surface sediment samples were collected from two fjords in Svalbard (Kongsfjorden and Rijpfjorden) in 2017, and they were searched for microplastics and polycyclic aromatic hydrocarbons (PAHs). PAHs were also investigated in 10 soil samples of Ny-Ålesund for local anthropogenic source analysis. The level of microplastics and other anthropogenic particles ranged from not detected (ND) to 4.936 particles/kg dry weight (DW). Fiber was the only shape of the microplastics found and three polymers (polyester, rayon and cellulose) were detected, which suggested that fisheries-related debris and textile materials were possible sources of microplastics and anthropogenic particles. For PAHs, the level of ∑26PAH was 9.2ng/g to 67.1ng/g (DW), and were dominated by lnP and BghiP, indicating petroleum combustion source. Further analysis revealed that traffic emissions from cars and diesel combustion from a local power plant were major sources of PAHs in soils of Ny-Alesund, while traffic emissions from ships were the dominate source of PAHs in sediments of Kongsfjorden and Rijpfjorden. A higher level of PAHs was observed in Ny-Alesund, confirming an anthropogenic input, while transport via ocean currents might contribute to the higher abundance of microplastics in Rijpfjorden. Further research and even long-term observation of pollutants are needed to fully understand the pollution status in polar regions.

Pollution levels, sources and risk assessment of polycyclic aromatic hydrocarbons in farmland soil and crops near Urumqi Industrial Park, Xinjiang, China

This study investigated the concentration, source, and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in farmland soil and crops around the Urumqi Industrial Park in Xinjiang, China. The total concentration of 16 different PAHs in the soil (Quantity: 51) and crop (Species: onion, cabbage, coriander, beans, spinach, celery, lettuce, and sunflower) samples ranged between 2.32 and 225.11 ng/g and between 132.44 and 504.03 ng/g respectively, with average values of 39.29 ± 2.39 ng/g for the soil samples and 295.81 ± 105.00 ng/g for the crop samples. The source analysis of PAHs was performed using the positive matrix factorization and ratio method and identified the high-temperature combustion of fossil fuels, the volatilization of petroleum, coke oven emissions, and traffic emissions as main sources of PAHs in soil. The ecological risk posed by the PAHs detected in the soil samples was within a safe range. The incremental lifetime cancer risk (ILCR) value quantifies resulting from human exposure to soil containing PAH is at a safe level except for the potential carcinogenic risk to children due to ingestion exposure (ILCRs > 1.0 × 10–6). The ILCR posed by crops exceed 1.0 × 10–6 and the risk from sunflower crop was the highest. The highest ILCR values for each crop high exposed for the adult female population. These results indicate that the farmland soil and crops near the Urumqi Industrial Park have been contaminated by PAHs and require urgent remediation to minimize adverse effects of exposure to carcinogens.

Distribution and Source Apportionment of Polycyclic Aromatic Hydrocarbons in Soils at Different Distances and Depths around Three Power Plants in Bijie, Guizhou Province

In this study, 16 polycyclic aromatic hydrocarbons (PAHs) optimally controlled by the U.S. Environmental Protection Agency (EPA) were investigated. Three representative coal-fired power plants were selected as the research areas in Bijie, Guizhou Province, and 24 soil samples were collected totally from power plants at different depths and at different distances from the point pollution sources (plants). The physicochemical properties and microbial characteristics of the soil from the three power plants were also studied. The results showed that 16 PAHs were detected in all soils of the three power plants, with total concentrations ranging from 0.2 to 12.2 mg kg−1, and that PAHs in the soils were mainly 2, 3 rings with percentages ranging from 42% to 82%. The proportions of low molecular weight (LMW) PAHs were higher near the contaminated plants. Moreover, since they were easily dispersed further away with atmospheric transfer, the proportions of lighter LMW PAHs were also higher far from the point source, while the proportions of heavier high molecular weight (HMW) PAHs were higher at some distance from the point source. In addition, the distribution patterns of PAHs in the soil at different depths were slightly different because the microbial activity in the surface soil at each sampling site was greater than that in the deeper soil, and the leaching behavior of each compound was different. Finally, based on the principal component analysis (PCA) method, coal combustion is not the only source of PAHs in soils from power plants, and vehicle emissions cannot be negligible.

Source Apportionment of Soil PAHs in Lanzhou Based on GIS and APCS-MLR Model

To evaluate the pollution by polycyclic aromatic hydrocarbons (PAHs) in the surface soil of the core urban area of Lanzhou, 62 topsoil samples were collected from the area. The soil samples were analyzed for the content of 16 priority PAHs, using gas chromatography-mass spectrometry. Descriptive statistical methods were used to characterize contamination by PAHs. An absolute principal component analysis-multiple linear regression (APCS-MLR) model was applied to determine the sources of PAHs in the soil samples, and the accuracy of the model results was verified. Finally, the main influence regions of each source were determined with a geo-statistical method. The results showed that the contents of Σ16 PAHs in the surface soils of Lanzhou ranged from 1069 to 7377 μg ·kg-1, with an average of 2423 μg ·kg-1. High molecular weight PAHs (4-6 rings) were dominant, accounting for 72.81% of the Σ16 PAHs. Verification results of the APCS-MLR model showed that the measured values were in good correspondence with the predicted values, which indicated that the model had good applicability for source apportionment of soil PAHs in the study area. The main sources of PAHs in Lanzhou were traffic emissions (35.42%), petroleum emissions (29.88%), and a mixture of coal and biomass combustion (33.91%). The sources were greatly affected by human activities, and high values were mainly distributed in traffic-intensive and industrial areas. The results indicated that the sources of soil PAHs were complex and influenced by anthropogenic activities in the study area. Stringent control measures should be placed on the sources and areas of influence that contribute to soil PAHs to reduce the emissions and the level of soil pollution resulting from PAHs.

Spatial distributions and sources of PAHs in soil in chemical industry parks in the Yangtze River Delta, China

The Yangtze River Delta (YRD) is one of the fastest developing areas in eastern China and contains many chemical industry parks. The profiles and sources of polycyclic aromatic hydrocarbons (PAHs) in soil in chemical industry parks and surrounding areas in the YRD were investigated by analyzing soil samples (n = 64) were collected in the YRD and Rudong chemical park (RD), a typical chemical park in the Yangtze River Delta. The total concentrations of 19 PAHs in the YRD soil samples were 16.3–4694 ng g−1 (mean 688 ng g−1), and the total concentrations of PAHs in RD were 21.6–246 ng g−1 (mean 75.4 ng g−1). The PAHs in soil in YRD were dominated by four-ring and five-ring PAHs, and the PAHs in RD were dominated by two-ring and three-ring PAHs. It suggested that PAHs may have been supplied to soil in YRD predominantly through coal combustion and vehicle emissions, PAHs in the soil of RD may be due to the volatilization and leakage of chemical raw material. According to the different distribution characteristics of PAHs, the ratio (1.5) of (2 + 3) rings/4 rings was proposed to identify the chemical source of PAHs. The PAH isomer ratios and principal component analysis/multiple linear regression (PCA/MLRA) results indicated that PAHs concentrations in soil in the YRD and RD are mainly supplied by industrial and traffic emissions. Incremental lifetime cancer risks (ILCRs) indicated that PAHs in soil pose negligible cancer risks to children and adults, but much stronger risks to children than adults.

Contents,Sources,and Ecological Risk Assessment of Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Soils of Various Functional Zones in Yangzhou City, China

The contents and sources of 15 US EPA priority polycyclic aromatic hydrocarbons (PAHs) were analyzed in 59 surface soil samples (0-10 cm depth) collected from six functional zones, including cultural and educational area, park, residential area, vegetable garden, gas station, and industrial area, in Yangzhou City. The toxicity equivalent content of benzo[a]pyrene (TEQBaP) was adopted to assess PAH risks in soils. The results showed that the contents of Σ15PAHs in soil samples ranged from 21 to 36118 μg·kg-1, with a median value of 295 μg·kg-1. The composition of PAHs was dominated by 4-6 ring PAHs. The average contents of Σ15PAHs in various functional zones in Yangzhou City was in the order of industrial area > gas station > cultural and educational area > vegetable garden > residential area > park. Correlation analysis showed that the contents of Σ15PAHs were significantly positively correlated with the contents of both TOC (P<0.05) and BC (P<0.01) in soil samples from whole Yangzhou City. However, the contents of Σ15PAHs had no significant correlations with the contents of both TOC and BC in soil samples within each functional zone except gas station, in which the contents of Σ15PAHs had a significant correlation with those of BC (P<0.01). The results of PAH ratios showed that the sources of PAHs in soils of various functional zones were mainly from oil leakage and the combustion of oil, coal, and biomass, although there were some differences among them. The values of ΣTEQBaP of 15 PAHs ranged from 2 to 4448 μg·kg-1 in the soil samples of Yangzhou City. According to the standard value of 33 μg·kg-1 of ΣTEQBaP for 10 PAHs in the soil environmental standard of Netherland, 45.8% of soil samples exceeded the standard in Yangzhou City. The percentages of soil samples exceeding the standard of various functional zones in Yangzhou City were in the order of industrial area (70%) > gas station (60%) > cultural and educational area (55.6%) > vegetable garden (50.0%) > residential area (30%) > park (10%). Hence, in all the functional zones of Yangzhou City, there were some soil samples with potential ecological risks, which was relatively higher in industrial area and gas station, and relatively lower in residential area and park.

Cancer risk assessment of soils contaminated by polycyclic aromatic hydrocarbons in Shanxi, China

To assess the human cancer risk exposed to soil contaminated by polycyclic aromatic hydrocarbons (PAHs) in Shanxi province, China, the total 33 samples in the surface soil were collected from 11 cities, and the priority 15 PAHs were analyzed using gas chromatography-mass spectrometry after the soxhlet extraction and silica-alumina column purification. As a result, the levels of ∑15PAH in soil varied from 66.2 to 2633 ng/g dry weight (dw) with a mean of 732 ng/g dw, and seven carcinogenic PAHs made up 42–69% of the total priority PAHs and had an average value of 367 (in the range of 33.2 to 1181) ng/g dw. Accordingly, the total concentrations of benzo[a]pyrene equivalents (BaPeq) for 15 PAHs ranged from 10.3 to 358 (average 98.3) ng/g dw, and the seven carcinogenic BaPeq accounted for above 90%. Subsequently, the possible sources of PAHs in soil were identified by isomer ratios, demonstrating that the combustion contributed to the main source. Finally, the incremental lifetime cancer risks (ILCR) of soil contaminated by 15 priority PAHs were estimated using the targeted chemical-specific approach. ILCR values were considered to be greater than 1 × 10−6 in 16 of 33 sites and followed a decreasing trend of adulthood > childhood > adolescence. Subsequently, the analysis of variance was performed by average ILCR value among the 11 cities (n = 3, p < 0.01), which indicated that the potential low cancer risk significantly increased for nearby residents in two areas, including Datong and Xinzhou, with the ILCR values of 4.61 ± 1.93 and 3.92 ± 2.54 per million, respectively. Therefore, the consumption of traditional coal should be controlled and partially replaced with the alternative energy sources. And the rigorous monitoring should be termly warranted to avoid the cancer risk for human being in agricultural area of Shanxi, China.

Source identification of PAHs in soils based on stable carbon isotopic signatures

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the environment and some exhibit carcinogenic and mutagenic toxicity. Three methods have been used for identification of PAHs sources in soils, including molecular diagnostic ratios, receptor models, and stable C isotopic signatures, with stable C isotopic ratios based on δ13C values being underutilized. Isotopic fractionation effects occur after environmental transportation of PAHs such as deposition and burial. This characteristic makes this method useful in source identification. Here, we provided a comprehensive review of tracing sources of soil PAHs using stable C isotopic fingerprinting technique. Fractionation of C isotopes occurs during formation and degradation processes of PAHs, making them useful tools to trace sources of PAHs in soils. The fundamentals of δ13C measurement and compound-specific isotopic analysis to trace sources of soil PAHs are summarized. Furthermore, for the first time, the biogeochemical cycle and contamination source evaluation based on δ13C signatures for soil PAHs are proposed. In addition, radioactive C isotope and stable H isotope ratios of PAHs are also briefly introduced as supplementary techniques. In short, these methods offer much promise, but still need work to fill in knowledge gaps. Establishing a C isotopic signature database to expand the utilization of this technique for tracing PAHs in soils is needed.

Characteristics, identification, and potential risk of polycyclic aromatic hydrocarbons in road dusts and agricultural soils from industrial sites in Shanghai, China.

Road dusts and agricultural soil samples were collected from eight sites close to steel mills, chemical plants, and municipal solid waste incinerator in suburban Shanghai. Sixteen polycyclic aromatic hydrocarbons (PAHs) in the United States Environmental Protection Agency (US EPA) priority controlled list were analyzed quantitatively using GC-MS. The total PAH concentrations ranged from 0.79 to 6.2μgg-1 in road dust samples with a mean value of 2.38μgg-1 and 0.26 to 0.54μgg-1 in agricultural soils with an average of 0.36μgg-1. The most abundant individual PAHs were phenanthrene, fluoranthene, pyrene, chrysene, and benzo(b)fluoranthene in dust samples and phenanthrene, fluoranthene, chrysene, and benzo(b)fluoranthene, benzo (k) fluoranthene in soil samples. Dominant compounds were four-ring and five- to six-ring PAHs, which accounted for 41.5 and 31.5% in dusts and 33.9 and 41.1% in soils. The spatial distribution of PAHs in dusts and soils was consistent. The wind direction could affect the spatial distribution of PAHs. Organic matter contents were found to be significantly positively correlated with PAH concentrations in both dusts and soils while grain size of particles had no correlation with PAH concentrations and could not significantly influence the distribution of PAH concentrations. PAH isomer ratios showed that combustion of grass, wood, and coal was important sources of PAHs in road dusts and agricultural soils. Toxic equivalent concentrations indicated seven kinds of carcinogenetic PAHs were major toxic equivalent concentration (TEQ) contributors, accounting for 98% of TEQ, in the road dusts and agricultural soils. Incremental lifetime cancer risk (ILCR) estimation results showed that the PAHs in the dusts and soils had potential cancer risk for both children and adults only by direct ingestion exposure. The TEQ and ILCR values of PAHs in road dusts were much higher than those in soils, which suggested that PAHs in road dusts could be an important source of PAHs in soils.

Predominant organic contaminants in arboretum soil of the Botanical Garden of Moscow State University: Report 2. Specific features of vertical distribution pattern of polycyclic aromatic hydrocarbons in the profile of urbo-soddy-podzolic soil

The distribution pattern of 12 polycyclic aromatic hydrocarbons (PAHs) in the profile of the urbo–soddy–podzolic soil of the arboretum of the Botanical Garden of Moscow State University is studied. Several accumulative zones of PAHs are specified, the role of environmental factors in the accumulation of polyarenes at soil geochemical barriers is shown, the ecological role of contamination rates is evaluated, and probable sources of PAHs in soils are determined. Data on the share of polyarenes with pronounced carcinogenic properties in the PAH spectrum and their toxicity equivalent with respect to benz(a)pyrene are given.

국내 토지이용도별 토양 중 다환방향족탄화수소류(PAHs)의 농도 수준 및 분포 특성

We investigated soil contamination depending on the land use by examining the contamination levels and distribution characteristics of 16 polycyclic aromatic hydrocarbons (PAHs) in the national soil. Total PAHs (the sum of 16 PAH concentrations) and carcinogenic PAHs (the sum of seven carcinogenic PAH concentrations) were 8.50~3,437.16 µg/kg and 2.94~2,136.96 µg/kg, respectively. The concentration of benzo(a)pyrene, one of the contaminants regulated by the soil quality standard in the nation, was ND~924.73 µg/kg. Its maximum value of 924.73 µg/kg was detected in railroad (Region 3) and is approximately 13% of the standard value for Region 3 (i.e., 7 mg/kg). We also investigated the characteristics of contamination sources of PAHs in soil of the upland, forests, roads, and railroads, examining the fraction distribution of PAHs concentration by the number of benzene rings against the total PAHs concentration. The results demonstrate that the mean fraction of 4~6-ring PAHs against total PAHs concentration in soil was in the range of 51.8~80.7% with relative abundance of high-molecular PAHs, showing that the origin of contamination is under the category of combustion sources. When the molecular indices (Flu/(Flu/Pyr), Ant/(Ant+Phe), InP/(InP+BP), and BaA/ (BaA+Chr)) were applied, they were also categorized as petroleum-based combustion sources. The individual PAH concentrations in soil by the land use were grouped into Regions 1, 2, and 3, which are statistically treated and are the parts of the national category system of soil quality standard. As a result, the concentration level of 16 PAHs was 0.02~2.63 µg/kg in Region 1, 0.05~4.26 µg/kg in Region 2, and 2.36~178.27 µg/kg in Region 3. The concentration level of 6 carcinogenic PAHs was 14.2~320.4% against that of benzo(a)pyrene in Region 3 and sites of recycling waste sleepers. Considering that there were similarities among PAHs in terms of structures and toxicities, it would be recommended to review other types of carcinogenic PAHs together with benzo(a)pyrene when developing the soil quality standards in the nation.

Polycyclic aromatic hydrocarbons in soils along the coastal and estuarine areas of the northern Bohai and Yellow Seas, China

Polycyclic aromatic hydrocarbons (PAHs) and their health risks in surface soils (n = 31) collected from coastal and estuarine areas of the northern Bohai and Yellow Seas (CEANBYS), China, were investigated. Total concentrations of PAHs ranged from 6.6 × 10(1) to 9.2 × 10(2) ng g(-1) dry weight, with an average of 3.1 × 10(2) ng g(-1) dw. The locations where greater concentrations of PAHs were observed were all near factories emitting black smoke or on the edge of the urban areas. These observations are consistent with concentrations of PAHs in soils being influenced by human activities, especially industrialization and urbanization. Concentrations of PAHs were significantly correlated with concentrations of organic carbon in soils. The patterns of relative concentrations and types of PAHs observed as well as knowledge of the potential sources were consistent with the primary sources of PAHs in soils of the CEANBYS being derived from the pyrolytic processes such as combustion of fossil fuel. The incremental lifetime cancer risks of exposing to PAHs for child, youth, and adult were 1.6 × 10(-6), 1.2 × 10(-6), and 1.9 × 10(-6).

County-scale distribution of polycyclic aromatic hydrocarbons in topsoil of the Yellow River Delta Region

The Yellow River Delta (YRD) is a typical agricultural and petrochemical industrial area in China. To assess the current status of polycyclic aromatic hydrocarbons (PAHs) of soil residues, soil samples (0–15 cm) (n = 82) were collected in Bincheng District, at the geographic center of the YRD. Concentrations of 16 PAHs (∑PAHs) ranged from 181.1 to 2176.0 μg kg−1, with an average concentration of 359.8 μg kg−1, showing significant increase along a rural-urban gradient (p ≤ 0.05). The contribution of naphthalene and phenanthrene to ∑PAHs was 48.6–57.6 %, and the contribution of low molecular weight (two- and three-ring) PAHs was 56.3–66.4 % from urban to rural. The significant correlations between ∑PAHs and soil organic C and total N concentrations were observed (p ≤ 0.05), indicated soil organic C and total N can affect PAH distribution in the study area, especially for low molecular weight PAHs. Principal component and multiple linear regression analysis reveal that soil PAHs have different sources in different area. Various petroleum inputs (volatilization, vehicular and non-vehicle combustion) were the main sources of soil PAHs in the urban and suburban areas, and the main source was biomass burning in the rural. In general, most soil PAH contaminations in the study area were classified as weakly polluted. Even so, soil PAH contamination from petroleum, particularly near petrochemical production sites, deserves further attention, because lighter PAH compounds are more labile and can react with other pollutants to form more toxic derivates.

Polycyclic aromatic hydrocarbons in the surface soil of Shanghai, China: Concentrations, distribution and sources

We quantified 18 polycyclic aromatic hydrocarbons (PAHs) in 54 surface soil samples covering an area of 6400 km 2 in Shanghai. An isopleth map of total concentrations of the 18 PAHs, which was constructed using an ordinary Kriging approach with log transformed data, clarified the regional variability and identified regional hot spots in the urban and industrial areas of Shanghai. These hot spots all suffer from high PAH pollution, suggesting that local human activities (e.g., vehicular traffic, petrochemical industry and coal combustion) may be the main contributors. Coal or oil fired power plants and their locations seem to be a significant factor controlling the PAH concentrations in surface soil. The higher molecular weight PAHs are often accumulated near pollution sources and are more heterogeneous in Shanghai soil, because they are less easily transported and biodegraded than 2 ring PAHs. The total concentrations are not correlated with soil total organic carbon. We successfully applied hierarchical cluster analysis (HCA) and principal components analysis (PCA) based on a centered log ratio procedure to explore the characteristics and possible sources of soil PAHs. The high PAH contamination in the Shanghai surface soil is mainly attributed to the contribution of pyrogenic sources (vehicular traffic pollution and combustion of coal and biomass). Furthermore, we applied PAH percentages by ring number, isopleth maps of total concentrations of 18 PAHs and source diagnostic ratios of PAHs to help assign the pyrogenic sources in Shanghai soils. Such map based approaches have only rarely been applied in investigations published in Organic Geochemistry.

Occurrence and human non-dietary exposure of polycyclic aromatic hydrocarbons in soils from Shenzhen, China

Twenty eight polycyclic aromatic hydrocarbons (PAHs) were determined for a total of 203 top soil samples collected from eight different land categories in Shenzhen, China during the winter of 2007. The concentrations, compositional profile, and the potential sources of PAHs in soil were discussed. Overall, PAH pollution in the soil of Shenzhen is still in the low-end of the world after 30 years rapid urbanization. Based on that, human exposure to soil PAHs via inhalation and soil particle intake were estimated as well. The concentrations of Sigma(28)PAHs in Shenzhen soil ranged from 2.68 to 17,767 ng g(-1) (average: 546 ng g(-1)). The highest levels of PAHs were found in the traffic land (average: 2104 ng g(-1)) and the lowest concentrations were detected in forest land (average: 144 ng g(-1)) in eight land categories. PAH isomeric ratios indicated that PAHs in Shenzhen soil were mainly derived from combustion. In the current pollution levels in Shenzhen, children aged 0 to 8 were the most sensitive sub-group of exposure to PAHs (59.2 ng (kg d)(-1)), and the exposure to PAHs for males (36.2 ng (kg d)(-1)) was more serious than for females (32.7 ng (kg d)(-1)). Inhalation was the major way of non-dietary exposure (over 96%).

Application of positive matrix factorization to identify potential sources of PAHs in soil of Dalian, China

Soil derived sources of polycyclic aromatic hydrocarbons (PAHs) in the region of Dalian, China were investigated using positive matrix factorization (PMF). Three factors were separated based on PMF for the statistical investigation of the datasets both in summer and winter. These factors were dominated by the pattern of single sources or groups of similar sources, showing seasonal and regional variations. The main sources of PAHs in Dalian soil in summer were the emissions from coal combustion average (46%), diesel engine (30%), and gasoline engine (24%). In winter, the main sources were the emissions from coal-fired boiler (72%), traffic average (20%), and gasoline engine (8%). These factors with strong seasonality indicated that coal combustion in winter and traffic exhaust in summer dominated the sources of PAHs in soil. These results suggested that PMF model was a proper approach to identify the sources of PAHs in soil.

Distribution of polycyclic aromatic hydrocarbons in thirty typical soil profiles in the Yangtze River Delta region, east China

Polycyclic aromatic hydrocarbons (PAHs) were quantified in 30 soil profiles from the Yangtze River Delta Region, in east China. Relative concentrations of PAH compounds with different benzene rings and ratios of fluoranthene to fluoranthene plus pyrene and benz(a)anthracene to benz(a)anthracene plus chrysene were used to identify the possible sources of soil PAHs. Total concentrations of 15 PAHs in topsoils ranged from 8.6 to 3881 μg kg −1 with an average of 397 μg kg −1. Half of the soil samples were considered to be contaminated with PAHs (>200 μg kg −1) and two sampling sites were heavily polluted by PAHs with concentrations >1000 μg kg −1. Phenanthrene was found in soils below a depth of 100 cm in half of the sampling sites, but the detectable ratio of benzo(a)pyrene decreased sharply from 100% in topsoil to 0 in the 4th horizon.

Historical and Chemical Assessment of the Sources of PAHs in Soils at a Former Coal-Burning Power Plant, New Haven, Connecticut

Soils from the manmade island in the Mill River (New Haven, CT) where a former power plant (English Station) operated for nearly 100 years had been previously shown to contain polycyclic aromatic hydrocarbons (PAHs) at concentrations that exceed the state's Department of Environmental Protection (DEP) Remediation Standard Regulations (RSRs) numerical cleanup criteria for industrial/commercial properties. Understanding the source(s) of these PAHs was important for property development and environmental management decisions. This study was designed to assess the industrial use history of the study area and conduct detailed chemical and organic petrographic characterization of the organic matter in the site's soils, particularly the PAHs, in order to determine their likely source or sources. Historical documents revealed that the English Station property is a largely manmade island and consists of sediments dredged from the Mill River, on various occasions from the late 1800s to at least 1936, to improve navigability. Throughout this time period, and as early as 1861, a manufactured gas plant (MGP) operated immediately downriver from the English Station site. The land use in the vicinity of the site and along the Mill River historically was industrial. In 1886, the English Station property was filled sufficiently to support operations of coal and wood storage yards. In 1901, and until the 1960s, the site was used for electric power generation via separate coal-fired power plants. In the 1960s, the boilers were converted to burn residual fuel oil rather than coal and operated until they were decommissioned in 1992. Sixty-six soil samples from the site were collected and, after assessing the detailed nature of the total (extractable) petroleum hydrocarbon (TPH), a subset was further analyzed using a combination of detailed PAH “fingerprinting” and petrographic analyses. The concentration and distribution (lateral or depth) of TPH in the soils analyzed appears unrelated to either the depth or location of the samples. Five distinct hydrocarbon sources could be recognized, namely: (1) tars associated with manufactured gas production (MGP), (2) residual (high boiling) petroleums of an unspecific origin, (3) particulate coal, (4) bottom ash (clinker) associated with coal combustion, and (5) “background” hydrocarbons associated with naturally occurring organic matter (e.g., plant debris). Organic petrographic analysis generally confirmed the hydrocarbon fingerprinting characterizations and also revealed coal and coke particles associated with the MGP tars in deeper soils, suggesting they share a common or contemporaneous source. The normalized distribution of the 44 PAH analytes provided detailed fingerprints that readily distinguished the five source materials. Because of the high concentration of PAH in MGP tars, and the widespread occurrence of MGP tar in the soils studied, the source of PAH in most soils studied, even those containing various mixtures, is largely attributable to the MGP tars. The residual petroleums, which appear physically associated with MGP tar in most soils, would appear to be the second most common source of PAH in the soils studied. The PAH derived from particulate coal and bottom ash are limited to specific areas of the site. Considering the area's industrial and dredging history, along with the widespread distribution of these PAH sources in the site soils, it is evident that the dredged sediments used to construct the island property contained MGP tars and petroleum wastes discharged from historic MGP and/or other industrial operations on the Mill River. The more recent coal combustion operations on the English Station property have contributed lower amounts of PAHs in the form of particulate coal and bottom ash, but with a limited distribution. The combination of the historical information with the chemical and petrographic data provided a stronger basis to establish PAH sources than either approach would have alone. Thus, this study demonstrates the value of combining extensive historical research and appropriate contaminant assessment methods in determining the source of contamination at sites with a long operational history. As a result of this study, the property owner's request for a widespread polluted fill variance from RSR compliance with the pollutant mobility criteria was granted by the DEP.