Ring Priority Polycyclic Aromatic Hydrocarbons Research Articles

Levels, distribution, origins, and human health risk evaluation of polycyclic aromatic hydrocarbons in groundwater around a petroleum depot wastewater discharge point

This study is an attempt to assess the influence of the oil storage depot discharges on proximate water sources in Ibadan, southwest Nigeria. Fifteen priority polycyclic aromatic hydrocarbons (PAHs) were examined in a total of 15 water samples (10 groundwater +4 surface water samples) utilizing gas chromatography–mass spectrometry, after extraction of the waters with dichloromethane and clean-up of the extracts. Results revealed that values of overall PAHs in groundwater (GW) and surface water (SW) varied from 0.01 to 3.45 mg/L (mean = 0.42 mg/L) and 0.01 to 0.09 mg/L (mean = 0.05 mg/L), correspondingly. The highest value of ∑15 PAHs (3.45 mg/L) was observed at 24 m to the discharge point. The ring wise distribution pattern of the PAHs in collected water samples follows the order: 2–3 rings >5–6 rings >4 – ring PAHs and low molecular weight (LMW) PAHs accounted for 90.73% relative to HMW (9.27%) in groundwater samples. The diagnostic ratios suggested that the PAHs pollution in water were likely from incomplete combustion of fossil fuels, vehicle emissions and released petroleum effluents from nearby depot. The concentration of carcinogenic PAHs in GW and SW ranged from 1×10−2to 9×10−2 mg/L and 1×10−2to 7×10−2 mg/L, correspondingly, which highlights possible human health risks. The values of hazard index (HI) for the studied samples via the oral ingestion and dermal exposure pathways are less than unity, suggesting no adverse non-carcinogenic health effects. The calculated incremental lifetime cancer risk (ILCR) for adults and children are in the 10−2–10−3 range, implying noteworthy possible carcinogenic health effects to human beings, with children being the most susceptible. Correspondingly, dibenzo [a, h] anthracence (DahA) and Benzo [a] pyrene (BaP) were established to be of greater carcinogenic threats in the waters taken from the study location. The study advocates complete discontinuance of discharge release into the neighboring environment.

Bioaccumulation of polycyclic aromatic hydrocarbons in Solea solea from Bizerte and Ghar El Melh Lagoons (Tunisia) and human health risk assessment

The present study objective was to assess polycyclic aromatic hydrocarbons in Bizerte and Ghar El Melh Lagoons Solea solea and to assess the potential risk to human health from its consumption. To reach these objectives twenty fish samples from each site were collected and 15 priority polycyclic aromatic hydrocarbons (PAHs) were analyzed in their muscles using high-performance liquid chromatography with a fluorescence detector. Total PAH sole concentrations from Bizerte and Ghar El Melh Lagoons were similar or lower to those recorded in other species from other regions across the world. In the studied fish species, the 2 and 3 ring PAHs are the dominated compounds that enter to the composition of PAHs which indicates that PAHs could be principally derived from a petrogenic origin for the both studied lagoons. The human health risk by sole consumption was evaluated and revealed to exhibit no hazard to the local population health concerning PAH intakes. The findings of this biomonitoring study will help in the implementation of sustainable environmental policies for effective water pollution control and the two investigated lagoons management.

Characterization, Sources, and Health Risks of PM2.5-bound PAHs During Autumn and Winter in Luoyang City

In this study, PM2.5 samples were collected synchronously at Gaoxin and Linxiao in Luoyang City during autumn and winter (4 October 2018 to 30 January 2019). Sixteen priority polycyclic aromatic hydrocarbons (PAHs) associated with fine particulate matter were analyzed by gas chromatography mass spectrometry (GC-MS). The concentrations and composition characteristics of the PAHs on clean and polluted days were studied. Diagnostic ratio analysis and principal component analysis (PCA) were used to identify the emission sources of PM2.5-bound PAHs and the equivalent carcinogenic concentration of benzo[a]pyrene (BaP) and incremental lifetime cancer risks (ILCRs) model were applied to evaluate health risks. During the sampling period, the concentrations of PAHs at Gaoxin and Linxiao ranged 24.33-90.26 ng·m-3 and 23.81-76.99 ng·m-3, respectively. With the increase in PM2.5 pollution, PAH concentrations increase significantly (the mean PAH concentration on polluted days was approximately 1.3 times higher than during clean days). PAH profiles at different polluting levels were similar; 4-ring PAHs (43%-48%) > 5-6 ring PAHs (32%-35%) > 2-3-ring PAHs (20%-22%). Diagnostic ratios and PCA demonstrated that PAHs in the study area were mainly derived from combustion sources including coal combustion, biomass burning, and motor vehicle emissions. The coal combustion was the main pollution source in the study area (clean days=49.28%-56.38%, polluted days=49.44%-60.60%). The results of the equivalent carcinogenic concentration of benzo[a]pyrene (BaP) and ILCR model revealed that the human health risk on polluted days was higher. Moreover, the cancer risks from adult exposure to PAHs were higher than those child exposure, which has an acceptable level of risk (<10-6).

Speciation, distribution and migration pathways of polycyclic aromatic hydrocarbons in a typical underground river system in Southwest China

Water, colloid, and suspended particulate matter (SPM) samples were collected during one given year at two sites from the Laolongdong (LLD) underground river in Southwest China and analyzed for 16 priority polycyclic aromatic hydrocarbons (PAHs), dissolved organic carbon (DOC), and particulate organic carbon (POC). The concentrations of the SPM-associated, colloid-associated, freely dissolved, and dissolved organic matter (DOM)-associated PAHs varied from 202 to 1731 ng/L, 142 to 956 ng/L, 228 to 1280 ng/L, and 7.3 to 173 ng/L, respectively. The mean percentages of 4- and 5–6 ring PAHs showed increasing trends along the order of the dissolved phase, colloidal phase and particulate phase. The behavior and fate of PAHs influence by DOC and POC were examined. Overall, organic carbon was the primary factor controlling the environmental behaviors and fates of the 16 PAH species in the LLD underground river. POC in underground river has more lipophilicity to PAHs in this study. The correlation analysis suggested that the migration pathways of PAHs from the surface soil to the underground river through the sinkholes and soil seepage water both had important contribution during the rainy season. However, PAHs mainly transferred through soil seepage water in the form of dissolved PAHs during the dry season.

Spatial-temporal distribution and transport flux of polycyclic aromatic hydrocarbons in a large hydropower reservoir of Southeast China: Implication for impoundment impacts

In order to investigate the impacts of dam-related water impoundment on the spatial-temporal variations and transport of anthropogenic organic pollutants, 15 priority polycyclic aromatic hydrocarbons (PAHs) were analyzed in water samples from the Shuikou Reservoir (SKR) of the Minjiang River. The SKR was formed after the construction of the Shuikou Dam, which is the largest hydropower station in Southeast China. The water samples were collected from the backwater zone of the SKR, in both the wet and dry seasons, corresponding to the drainage and impoundment periods of water flow, respectively. The concentrations of the dissolved PAHs in surface water from the wet season (average of 161 ± 97 ng L−1) were significantly higher (ANOVA, p < 0.01) than those from the dry season (average of 43 ± 21 ng L−1). PAH concentrations in the SKR decreased from upstream (industrialized cities) to downstream (rural towns or counties), indicating high PAH loads caused by intensive urbanization effects. The high proportions of 3-ring PAHs in the wet season were from local sources via surface runoff; while the elevated proportions of 4- to 6- ring PAHs in the dry season reflected atmospheric deposition emerged of these PAHs and/or volatilization of 3-ring PAHs enhanced. Molecular diagnostic ratios of PAH isomers in multimedium and principal component analysis indicated that PAH presence in the SKR was mainly attributed to pyrogenic origin. The isomeric ratios of fluoranthene to fluoranthene plus pyrene in the wet season were homogeneous, implying that there were continuous new inputs along the riverine runoff. However, these ratios showed spatial downward trend in the dry season, indicating continued degradation of PAHs occurred along the transport path during the impoundment period. The input and output fluxes of PAHs in the SKR were 5330 kg yr−1 and 2991 kg yr−1, revealing that the reservoir retained contaminants after impoundment of the hydropower dam.

Characterization of PM2.5-Bound Polycyclic Aromatic Hydrocarbons at Two Central China Cities: Seasonal Variation, Sources, and Health Risk Assessment.

In this study, ambient PM2.5 samples were collected from October 2014 to August 2015 in urban area of Luoyang (LY) and Pingdingshan (PDS), two medium-size industrial cities in central China. Sixteen priority polycyclic aromatic hydrocarbons (PAHs) were analyzed to investigate the seasonal variation, potential pollution sources, and health risk of PAHs bound to PM2.5 (PM2.5-bound PAHs). The diagnostic ratios analysis and positive matrix fraction (PMF) model were used to identify potential sources of PM2.5-bound PAHs. The annual average concentrations of PM2.5 and PM2.5-bound PAHs were 128μgm-3 and 73ngm-3 for LY, and 119μgm-3 and 182ngm-3 for PDS, respectively, both displaying seasonal trends with higher concentrations in winter and autumn than in spring and summer. BaP equivalent concentrations were 14.4 and 16.5ngm-3 in LY and PDS, respectively. The predominant PAHs were 4-6 ring PAHs, with contribution of more than 80% at both sampling sites. PMF analysis revealed that coal combustion was the most important source of PM2.5-bound PAHs in LY and PDS, accounting for 37% and 39%, respectively, followed by traffic emissions (34% and 33% in LY and PDS, respectively). The average inhalation cancer risk (ICR) for a lifetime of 70years were 12.5 × 10-4 and 14.3 × 10-4 in LY and PDS, respectively, which were much higher than US EPA guideline limit of 10-6. The traffic source and coal combustion source contributed the highest ICR values in LY and PDS, respectively.

Distribution, sources and ecological risk assessment of PAHs in surface seawater from coastal Bohai Bay, China

The distribution, composition, potential sources and ecological risk of 16 US EPA priority polycyclic aromatic hydrocarbons (PAHs) were investigated in surface water from coastal Bohai Bay. The PAH concentrations ranged from 48.0 to 607 ng L−1 with the mean value of 267 ng L−1 in dissolved phase and 198 to 935 ng L−1 with the mean value of 424 ng L−1 in particle-associated phase, and decreased following the order: Qinhuangdao (QHD) > Caofeidian (CFD) > Huanghuagang (HHG). The 2–3 ring PAHs accounted for 79.9% to 86.2% in particle-associated phase and 65.6% to 73.2% in dissolved phase of total 16 PAHs, in which naphthalene (Nap) was the most dominant compound. The PAHs in surface seawater mainly originated from petrogenic sources according to the molecular ratios of benzo[a]anthracene/228 and fluoranthene/202. Risk quotients indicated that there was potential ecological risk for PAHs in surface seawater, especially for pyrene and fluorene.

Chemical composition and size distribution of particulate matters from marine diesel engines with different fuel oils

In this work, detailed physicochemical characteristics of particulate emissions were investigated over ranges of fuel properties, particles size distribution, chemical compositions and toxicity based on dynamometry experiments with marine diesel engines. The results indicated that lower fuel sulfur content (FSC) can decrease the specific emissions of total particle matters (PM). Organic carbon (OC) emissions were more than elemental carbon (EC), especially for 2-stroke marine diesel engine with heavy fuel oil (HFO), and carbonaceous substances were found to be load and size dependent. The suppression effect of low-sulfur light diesel fuel (LSDF/DF) for PM mass emissions was exhibited mostly in the reduction of OC and sulfate, compared with high-sulfur light diesel fuel (HSDF). PM mass emissions with low-sulfur HFO were still higher due to larger OC emissions. Emissions of 16 priority polycyclic aromatic hydrocarbons (PAHs) were highest in particle-phase PAHs, among which 3 and 4-benzene ring PAHs were predominant. Flua and Pyr were the PAHs with the highest emissions in the PM emitted from marine diesel engines. The PAHs had very high toxic equivalent, with the highest contribution of BaP and DahA. According to benzene rings number, the proportion of 5-benzene ring PAHs had the highest equivalent toxic concentration. Size distribution of PAHs had high correlations with OC and the PM with small size had higher equivalent toxicity concentration.

Polycyclic aromatic hydrocarbons in sediments and marine organisms: Implications of anthropogenic effects on the coastal environment

Intensive human activities aggravate environmental pollution, particularly in the coastal environment. Sixteen priority polycyclic aromatic hydrocarbons (PAHs) were determined in the sediments and marine species from Zhanjiang Harbor, a large harbor in China. The total PAH concentrations ranged from 151 to 453 ng/g dry weight (dw) in sediments and from 86.7 to 256 ng/g wet weight (ww) in organism tissues. High levels of PAHs occurred in the sample sites next to the estuary. A decrease in PAH levels was observed in comparison to the previous survey prior to 2012. Fish exhibited lower lipid weight normalized PAH concentrations than the other species, which may be related to their efficient metabolic transformation. Three ring PAHs dominated both in marine sediments and species, but low molecular weight PAHs exhibited higher proportions in biota than in sediments (p < 0.05). Petrogenic and pyrolytic sources both contributed to the occurrence of PAHs, and the latter became increasingly important in the study area. The ecological risk from PAHs in the sediments was relatively low (9% incidence of adverse biological effect) according to the effects-based sediment quality guideline values. Exposure to PAHs via consuming seafoods might pose a health risk to local residents. Overall, these results revealed anthropogenic activities in the coastal area have an impact on the local ecosystem.

Source contributions of Polycyclic Aromatic Hydrocarbons in soils around oilfield in the Brahmaputra Valley

Surface soils from Borholla oilfield in the upper Brahmaputra Valley in India were studied for the USEPA's 16 priority Polycyclic Aromatic Hydrocarbons (PAHs). Analysis of PAHs was carried out by high performance liquid chromatography (HPLC) system equipped with an UV detector. Seasonality in PAHs concentrations was evident and the concentrations were found to be greater in post-monsoon season. There has been a dominance of low molecular weight PAHs (80–90% of total PAHs) indicating recent deposition from combustion sources. The concentration profiles appeared in the decreasing order of 3-ring >2-ring >4-ring >5-ring >6 ring PAHs. The sources of PAHs were identified using isomer pair ratios and Principal Component Analysis-Multiple Linear Regression (PCA-MLR) and Positive Matrix Factorisation (PMF). The ratios of diagnostic pairs indicated for both pyrogenic and petrogenic input of PAHs. The PCA-MLR modelling revealed that the <16% of contribution came from petrogenic origin and the rest 85% was found to be from pyrogenic sources. The PMF model also shown that <19% of PAHs source were petrogenic origin whereas rest from pyrogenic origin. The correlations of black carbon (BC) with PAHs also supported the pyrogenic contribution. The analysis of air mass back trajectories revealed that there has been contribution of both local and distant sources, through long range transport of pollutants, which were deposited to the site.

Priority Polycyclic Aromatic Hydrocarbons (PAHs): Distribution, Possible Sources and Toxicity Equivalency in Urban Drains

Wastewater from urban areas constitutes one of the major sources of pollutants contributed to aquatic ecosystem. This study was carried out to elucidate the occurrence and possible source of US Environmental Protection Agency identified 16 priority polycyclic aromatic hydrocarbons (PAHs) in water and sediments from the urban wastewater drains in Delhi, India. A total 60 samples (water and sediment) collected during year 2011–2012, and analyzed the following USEPA methods. Water and sediment samples were extracted using liquid-liquid and ultrasonication techniques, respectively. Glass column chromatography with activated silica was used for sample extracts clean-up, followed by quantification on HPLC equipped with diode array detector at 254 nm wavelength using mixture of acetonitrule and water as mobile phase. Concentrations of total 16 PAHs (∑16PAHs) in all drain water samples ranged from 0.29–35.22 μg/L (mean ± SD, 10.83 ± 10.66 μg/L), predominated by two- and three -ring PAHs. The ∑16PAHs concentrations in all collected sediments ranged between 220–19321 μg/kg (mean±SD, 5574 ± 6820 μg/kg) dry weights. High molecular weight PAHs (≥4-ring PAHs) were dominant in sediment samples. Benzo(a)pyrene equivalent (BaPeq), a relative carcinogenic potential to the corresponding PAHs to BaP was estimated and presented. A selected number of concentration ratios of specific PAHs compounds were calculated and used to diagnose the possible sources of PAHs contamination. The diagnostic ratios reflected pyrogenic input from gasoline or diesel powered vehicular emissions as the major source of PAHs. The levels of PAHs observed in water and sediments were compared with similar studies undertaken in other regions of the world.

Distribution pattern of polycyclic aromatic hydrocarbons in particle-size fractions of coking plant soils from different depth

The concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs) in four size fractions (<2, 2-20, 20-200, >200 μm) in soils at different depth from a heavily contaminated crude benzol production facility of a coking plant were determined using GC-MS. Vertically, elevated total PAHs concentrations were observed in the soils at 3.0-4.5 m (layer B) and 6.0-7.5 m (layer C), relatively lower at 1.5-3.0 m (layer A) and 10.5-12.0 m (layer D). At all sampling sites, the silt (2-20 μm) contained the highest PAHs concentration (ranged from 726 to 2,711 mg/kg). Despite the substantial change in PAHs concentrations in soils with different particle sizes and lithologies, PAHs composition was similarly dominated by 2-3 ring species (86.5-98.3 %), including acenaphthene, fluorene, and phenanthrene. For the contribution of PAHs mass in each fraction to the bulk soil, the 20-200 μm size fraction had the greatest accumulation of PAHs in loamy sand layers at 1.0-7.5 m, increasing with depth; while in deeper sand layer at 10.5-12.0 m, the >200 μm size fraction showed highest percentages and contributed 81 % of total PAHs mass. For individual PAH distribution, the 2-3 ring PAHs were highly concentrated in the small size fraction (<2 and 2-20 μm); the 4-6 ring PAHs showed the highest concentrations in the 2-20 μm size fraction, increasing with depth. The distribution of PAHs was primarily determined by the sorption on soil organic matter and the characteristics of PAHs. This research should have significant contribution to PAH migration study and remediation design for PAHs-contaminated sites.

Sources of polycyclic aromatic hydrocarbons to sediments of the Bohai and Yellow Seas in East Asia

[1] The coasts of Bohai Sea (BS) and Yellow Sea (YS) in China support almost one-quarter of its population and provide more than one-third of the national GDP. BS and YS are downwind of the Asian continental outflow in spring and winter as influenced by the East Asian monsoon. This makes the two seas important sinks of land-based pollutants associated with the Asian continental outflow. The sixteen U.S. EPA proposed priority polycyclic aromatic hydrocarbons (PAHs) in 130 surface sediment samples collected from BS and YS were measured. Combined with our previous PAH data of 90 PM2.5 samples from the upwind areas, the sources of the PAHs in BS and YS were apportioned using positive matrix factorization (PMF) modeling. Four sources were identified: petroleum residue, vehicular emissions, coal combustion and biomass burning. Petroleum residue was the dominant contributor of PAHs in the coast of the Bohai Bay probably due to Haihe River runoff, oil leakage from ships and offshore oil fields. The contribution of vehicular emissions in BS was higher than that in YS, and the reverse was true for coal combustion and biomass burning. This difference in the source patterns in the sediments of the two seas could be attributed to the different PAH emission features of the upwind area related to demographic and economic conditions, as well as the marine geography. The ratios of selected 4–6 ring PAHs in the sediments compared well with those of the PM2.5 of the upwind areas, implicating that the particle phase PAHs in the atmosphere play an important role in the source to sink process of the pyrogenic PAHs in the region.

Distribution and mass inventory of polycyclic aromatic hydrocarbons in the sediments of the south Bohai Sea, China

Recent occurrence, distribution and mass inventories of 16 priority polycyclic aromatic hydrocarbons (PAHs) proposed by USEPA in the south Bohai Sea (BS) were studied based on the analytical data of 71 surface sediment samples. The concentrations of 16 PAHs varied from 37 to 537ngg−1 (dry weight). A clear difference was observed between the coastal Bohai Bay (CBB) and its adjacent BS (ABS) in the distribution and compositions of PAHs. The petrogenic source of phenanthrene in CBB was attributable to the industrial wastewater, fugitive fuel leakages from ships and offshore oil production. Four to six ring PAHs were predominantly from the coal and wood combustions in the whole area. The estimated PAH input to the south BS (43,000km2, 56% of BS in area) was 36.6tonyr−1, indicating that the study area was one of the important reservoirs of PAHs in world.

Polycyclic aromatic hydrocarbons in water, sediment, soil, and plants of the Aojiang River waterway in Wenzhou, China

The town of Shuitou was renowned as the leather capital of China because of its large-scale tanning industry, but the industry's lack of pollution controls has caused severe damage to the local water system. This study determined 15 priority polycyclic aromatic hydrocarbons (PAHs) in water, sediment, soil, and plant samples collected from Aojiang River and its estuary. The total PAHs ranged from 910 to 1520 ng/L in water samples. The total PAH in sediments were moderate to low in comparison with other rivers and estuaries in China, but the relative proportions of PAHs per million people are high when considering the population size associated with each watershed. Ratios of fluoranthene/pyrene and PAHs with low/high molecular weight suggest a petrogenic PAH origin. The PAH composition profile in soil was similar to that in sediment with 4-6 ring PAHs being dominant. The PAHs with 2-3 rings were the dominant species in plant leaves. There were no correlations between PAHs in soils and in plants, suggesting that PAHs accumulate in plant leaves through absorption from the air. The general observation of elevated PAH concentrations in all matrix suggests a possible contribution by the local leather industry on the PAH concentrations in the Aojiang watershed.

FATE OF POLYCYCLIC AROMATIC HYDROCARBONS DURING COMPOSTING OF OILY SLUDGE

ABSTRACT In order to assess the effectiveness of aerobic degradation with emphasis on the 16 U.S. EPA priority polycyclic aromatic hydrocarbons (PAH), oily sludge generated by a dissolved air flotation flocculation unit of a wastewater treatment plant in a petroleum refinery was amended with remediated oil‐contaminated soil and non‐mature garden waste compost 40:40:20 (wet weight) respectively. About 21 t of the mixture with a top‐layer formed by 30 cm of remediated soil was treated in a 28 m3 air‐forced reactor. The PAH concentration was monitored for 370 days. In the top‐layer, a reduction of 88 % of the total extractable PAH was measured at day 62 and a final reduction of 93 % at day 370 days. In the mixture, a reduction of 72 % in total PAH was measured at day 62, followed by fluctuation in concentration with a final measured reduction of 53 % at day 370. The analysis of individual PAH in the mixture suggested that volatilization and biodegradation are the main mechanisms responsible for the reduction of 2 ring PAH and 3–4 ring PAH, respectively. Fluctuation of 5–6 ring PAH concentrations with increase observed at the end of the period might result from a combination of the following: (i) sequestration of large PAH in the organic matrix (reducing bioavailability, biodegradability and eventually, extractability) and desorption as composting progresses; (ii) heterogeneous distribution of the stable large PAH in the mixture, thus affecting sampling. It was concluded that one‐time composting in static‐aerated biopiles with organic amendments as the sole strategy to treat oily sludge is very effective in reducing the content of 2–4 ring PAH, but it is not effective in reducing the content of 5–6 ring PAHs, even after a relatively long time span (370 d). The concentrations measured in the remediated soil that formed the top layer after 62 days of composting suggests that further relevant reduction of residual PAH (89% of total PAH and 69% of 5–6 ring PAH) can be obtained if the contaminated masses are exposed to a second thermophilic phase. This could be achieved by adding new easily biodegradable organic amendments to the contaminated masses after some months of composting, remixing and composting again for a minimum additional period of 2 months.

PAHs Contamination in Bank Sediment of the Yamuna River, Delhi, India

This study was performed to elucidate the distribution, concentration trend and possible sources of PAHs in bank sediment of river Yamuna in Delhi, India. The levels of 16 priority polycyclic aromatic hydrocarbons (PAHs) were analyzed during pre-monsoon, monsoon and post-monsoon seasons in the sediment fraction < 53 microm. Reference standards and internal standards were used for identification and quantification of PAHs by HPLC. The sum of 16 PAH compounds ranged from 4.50 to 23.53 microg/g with a mean concentration of 10.15 +/- 4.32 microg/g (dry wt.). Among 5 sites studied, the site, Income Tax Office (ITO) was found to be the hotspot attaining highest concentration. Predominance of 2-4 ring PAHs suggests a relatively recent local sources of PAHs in the study area. Moreover, molecular indices based source apportionment also illustrates pyrogenic source fingerprint of PAHs. No significant temporal trend was observed.

Polycyclic aromatic hydrocarbons in the surface soils from outskirts of Beijing, China

Surface soils from the outskirts of Beijing were analyzed for 16 priority polycyclic aromatic hydrocarbons (PAHs) using gas chromatography and mass spectrometry (GC–MS). The distribution map of total PAHs content was obtained as a contour plot. The concentration range of 16 PAHs varied by over two orders of magnitude from 0.016 μg g −1 in rural to 3.884 μg g −1 in suburban soils with the relatively standard deviation of 70.5%, showing large differences in the extent of PAHs pollution at the various sampling sites. It was notable that the concentration of BaP was 0.005–0.270 μg g −1 with a mean of 0.055 μg g −1. In general, the distribution of PAHs centered on the high molecular weight PAHs known to be carcinogenic. The 4–6 ring PAHs represented about 66% in rural samples and 70% in suburban soils of the total PAHs found. There was relatively good relationship among most of the individual PAHs and the compounds of Pyr, BaA, Flu, BbF, BaP, Chr and Ph gave strong correlation ( r > 0.8) with the sum of PAHs. The selected marked compounds, a principal component analysis (PCA) and special PAHs compound ratios (Ph/An vs Flu/Pyr; ∑ COMB ∑ EPA - PAHs ) suggest the pyrogenic origins, especially traffic exhausts, are the dominant sources of PAHs in Beijing outskirts soils.