Total Priority Polycyclic Aromatic Hydrocarbons Concentrations Research Articles

High levels of Polycyclic Aromatic Hydrocarbons in the Date Mussel (Lithophaga lithophaga) from Bizerte coast (northern Tunisia): Sources and human health risk implications

The date mussel Lithophaga lithophaga is protected by law in Tunisia. Still, illegal consumption of this luxury seafood has increased over time due to high demand and high prices, which have made the species regularly available in the seafood market of Bizerte, putting wild stocks at risk of decline. To raise public awareness of the risks to human health associated with the consumption of this bivalve, 16 priority polycyclic aromatic hydrocarbons (PAHs) were quantified in the soft tissue of the species, which was collected from two sites of high fishery pressure in the bay and lagoon of Bizerte. Total PAHs concentrations differ significantly between the studied sites ranging from 0.45 to 546.05 μg g−1 d.w., and were associated with port activity and the petroleum industry. The benzo(a)pyrene toxic equivalent factor and excess cancer risk showed both high values exceeding permissible limits in the polluted site. These findings provide valuable information regarding the distribution of PAHs in mussels from wild ecosystems that could be useful to prevent consumer intoxication and improve awareness against illegal harvesting of this species.

Spatial modeling and source identification of PAHs in soils and roadside dusts from Hangzhou, a new first-tier megcity of China

Soil (n = 100) and roadside dust (n = 97) samples across a new first-tier megacity (Hangzhou, East China) were collected to systematically survey the spatial patterns and sources of 16 priority Polycyclic aromatic hydrocarbons (PAHs). The total PAH (Σ16PAH) concentrations in the surface soils exhibited an average of 329 ± 168 ng/g with a range of 67.7–2950 ng/g. 45 % of soils suffered from the weak - heavy PAH contaminations. By contrast, the average concentration of Σ16PAHs in roadside dusts was approximately three times higher than that found in the soils. Within both soil and dust samples, PAHs with a high molecular weight (HMW, 4–6 rings) were the dominant homologs. Spatial lag models revealed that industrial and traffic-related variables significantly influenced the spatial distribution of PAHs in dusts. Furthermore, a positive matrix factorization model indicated that Σ16PAHs in soils and dusts mainly derived from coal-related production/combustion and automobile exhaust emission (65.0 % and 77.9 %, respectively). The isotopic composition analysis conducted on heavily polluted samples further demonstrated that HMW PAHs in these soils and dusts predominantly originated from coal processing and liquid fossil fuel combustion. Overall, the findings of this study suggest that the intensive urban construction and human activities strongly stimulated PAH accumulations in soils and dusts during the rapid urbanization of Hangzhou.

Polycyclic aromatic hydrocarbons in suspended particulate matter of a region influenced by agricultural activities in northeast Brazil

Suspended particulate matter (SPM) samples were collected in rainy (2016) and dry (2017) seasons from the Japaratuba River in Northeast Brazil and analyzed the concentration of 16 priority polycyclic aromatic hydrocarbons (PAHs). The results were applied to measure the seasonal variations, spatial distributions, and source apportionment in the estuarine SPM systems. The seasonal variation in total PAHs was not statistically significant, although the highest levels were found in the rainy season, where the total PAHs concentrations in the Japaratuba River ranged from 71 to 1598 ng g−1, with a mean value of 453 ng g−1. In the dry season, the concentrations ranged from 65 to 459 ng g−1, with a mean value of 257 ng g−1. The composition profiles of PAHs at different sites were not significant. At most sampling sites, 5-ring and 6-ring compounds (indeno(1,2,3-cd)pyrene, dibenzo(a,h)anthracene, and benzo(g,h,i)perylene) were the most abundant components, followed by 2-ring and 3-ring compounds (naphthalene and phenanthrene). The use of diagnostic ratios (DR) and principal component analysis (PCA) showed that the PAHs mainly originated from pyrogenic sources. Ecological risk assessment indicated that the PAHs could cause moderate impacts on organisms, suggesting the need for preventive measures.

Effects of architecture structure on volatile organic compound and polycyclic aromatic hydrocarbon diffusion in Singapore's Integrated Transport Hubs

Millions of passengers wait for buses at Integrated Transport Hubs (ITH) daily in metropolitan cities. Environmental exposure and associated risk for passengers is of great public concern. In this study, eight volatile organic compounds (VOCs) and the 16 EPA priority polycyclic aromatic hydrocarbons (PAHs) were analyzed in airborne samples collected from indoor waiting areas (Indoor) and bus parks of nine Singapore ITH, which comprises of two types of architectural structure (i.e., fully sheltered and open/partially enclosed). The median concentrations of total VOCs (TVOCs), total gaseous PAHs (TgPAHs) and total airborne particles-adsorbed PAH (TpPAHs) concentrations in Indoor were 30.42 μg/m3, 18.99 ng/m3 and 1.38 ng/m3; respectively. A strong correlation (r ≥ 0.75, p < 0.001) was observed between Indoor and bus parks air compounds. The “Indoor” to bus park pollutant concentration ratio (I/B ratio) showed lower values in the bus interchanges with fully sheltered bus parks (TVOCs: 0.98; TgPAHs: 0.76; TpPAHs: 0.71) than those with open/partially enclosed ones (TVOCs: 1.28; TgPAHs: 1.31; TpPAHs: 0.90). This result suggests that fully sheltered structure may cause the accumulation of air pollutants. The daily VOC and PAH exposure for commuters were further estimated by considering inhalation and dermal doses using Monte Carlo simulation (n = 100,000). Overall, the result showed that the risk is still within international guideline values. In sum, the effect of architecture structure on the migration of air pollutants should be taken into consideration in future transport hub design to reduce pollutant exposure to commuters.

Polycyclic Aromatic Hydrocarbons and Potentially Toxic Elements in Soils of the Vicinity of the Bulgarian Antarctic Station “St. Kliment Ohridski” (Antarctic Peninsula)

The investigation conducted was dialed to quantitative and qualitative evaluation of 15 priority polycyclic aromatic hydrocarbons (PAHs) and Potentially Toxic Elements (Cu, Pb, Zn, Cd, Ni, and Cr) is soils and cryoconites on “St. Kliment Ohridski” Antarctic station territory and its vicinities. Estimation of benzo(a)pyrene (BaP)–equivalents, PAHs and different PAHs isomer pair ratios were used for identification of general toxicity, nature and origin of individual PAHs and their groups. Total concentrations of PAHs in BaP–equivalents showed, that ∑15PAH of all selected points was higher than the threshold concentration (20 μg × kg−1–Russian environmental legislation) for benzo(a)pyrene. Different PAHs isomer ratios showed the natural (petrogenic) source of PAHs at all soils examples (except Cryosol Toxic Transportic). The maximum content among potentially toxic elements was recorded for Zn (75.7 mg × kg−1 at L26), the minimum for Cd (0.201 mg × kg−1 at L1A). Average concentrations of potentially toxic elements are generally lower compared to the results of previous studies. Application of Igeo index, characterizes the majority of the studied soils as unpolluted or practically unpolluted. Data obtained indicates that there is no current critical anthropogenic load on the environmental components of the landscapes investigated.

Soil PAHs contamination effect on the cellular and subcellular organelle changes of Phragmites australis Cav.

The concentrations of ∑16 priority polycyclic aromatic hydrocarbons (PAHs) for soils, roots, and above-ground parts of reed (Phragmites australis Cav.) were determined on different monitoring plots located near the city of Kamensk-Shakhtinsky, southern Russia, where historically received industrial sewage and sludge. The total PAHs concentration in monitoring soil plots was significantly higher than those in the background site which situated at the distance of 2km from the contamination source. Accordingly, the maximum accumulation was found for phenanthrene and chrysene among the 16 priority PAHs in most of the plant samples collected in the impact zone. The effects of PAHs' pollution on changes of Phragmites australis Cav. cellular and subcellular organelles in the studied monitoring sites were also determined using optical and electron microscopy, respectively. The obtained data showed that increasing of PAHs contamination negatively affected the ultrastructural changes of the studied plants. Phragmites australis Cav. showed a high level of adaptation to the effect of stressors by using tissue and cell levels. In general, the detected alterations under the PAHs effect were possibly connected to changes in biochemical and histochemical parameters as a response for reactive oxygen species and as a protective response against oxidative stress. The obtained results introduce innovative findings of cellular and subcellular changes in plants exposed to ∑16 priority PAHs as very persistent and toxic contaminants.

Determination of Polycyclic Aromatic Hydrocarbons (PAHs) in the Brackish Water and Sediments of Citarum Irrigation System, Pakis Jaya, Karawang, Indonesia

Fifteen priority polycyclic aromatic hydrocarbons (PAHs) were determined in the sediments and brackish water of Citarum Irrigation System (CIS), Pakis Jaya, Karawang Regency. The samples were analyzed with liquid-liquid extraction for brackish water and Soxhlet Extraction for sediments. The final concentration of PAHs was determined with Gas Chromatography-Mass Spectrometry (GC-MS) and the origins of PAHs were identified through diagnostic ratios method. The total PAH concentrations ranged from 1782 to 2386.88 ng/L in water and from 113 to 405 ng/g dry weight (dw) in sediments. The concentration of total PAHs in sediment was lower than the SQG effects range-low (3442 ng/g). High molecular weight of PAHs dominated both in sediments and water. The origins of PAHs in the sediment and water-based on diagnostic ratios were from petrogenic and pyrogenic sources including petroleum, petroleum combustion, and combustion of organic materials. Overall, environmental conditions in the Citarum irrigation system and its river mouth was moderate level of PAHs contamination.

Distribution Characteristics and Source Analysis of Polycyclic Aromatic Hydrocarbons in Salinized Farmland Soil from the Oil Mining Area of the Yellow River Delta

Eighty-nine soil samples were collected from the Binzhou oil mining area of the Yellow River Delta (including 83 farmland soil samples and 6 soil samples from an oil extraction area). A total of 16 US-EPA priority polycyclic aromatic hydrocarbons (PAHs) were measured by gas chromatography-mass spectrometry (GC-MS). Principal component analysis (PCA) and positive matrix factorization (PMF) were employed to investigate potential source apportionment of PAHs in the farmland soil. The total PAH concentrations ranged from 31.5 μg·kg-1 to 1399.4 μg·kg-1 (dry weight) with an arithmetic mean concentration of 119.4 μg·kg-1. The characteristics of PAHs showed that 4- to 6-ring PAHs were slightly dominant in this study area, and most of the PAHs were significantly correlated (P<0.01), which indicates that the sources of the PAHs had some similarities in this sampling area. Source apportionment results derived from two different models were similar, indicating that the sources of PAHs were coal combustion, biomass combustion, fossil fuel combustion, and diesel combustion. The results of the PMF were more detailed, with the following four factors being identified:gasoline combustion (24.05%), diesel combustion (6.17%), low-temperature pyrolysis processes (60.67%), and coal combustion (9.11%).

Polycyclic aromatic hydrocarbons in sediments of the Amazon River Estuary (Amapá, Northern Brazil): Distribution, sources and potential ecological risk

The distribution, sources and potential ecological risk of priority polycyclic aromatic hydrocarbons (PAHs) in sediment from the Amazon River Estuary (Macapá and Santana, Amapá, Northern Brazil) were investigated. The total PAHs concentration (∑PAH) ranged from 22.2 to 158.9 ng g−1 dw (mean value 49.4 ng g−1 dw). PAHs levels in the study area were relatively low than those in nearby areas and other coastal zones worldwide, and could be considered as baseline for PAHs in Amazonic sediments. PAHs ratios and the statistical analysis showed that fossil fuel and biomass combustions, primarily from local sources, were the dominant PAHs origins. The potential ecological risk was assessed on the basis of the sediment quality guidelines, and it was found that PAHs in the sediments of the Amazon River Estuary do not cause adverse effects on living organisms; however, the abundance of naphthalene and the presence of dibenzo[a,h]anthracene and benzo[a]pyrene deserve more attention.

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.

Polycyclic aromatic hydrocarbon in urban soils of an Eastern European megalopolis: distribution, source identification and cancer risk evaluation

Abstract. This study explores qualitative and quantitative composition of 15 priority polycyclic aromatic hydrocarbons (PAHs) in urban soils of some parkland, residential and industrial areas of the large industrial centre of Saint Petersburg (Russian Federation) in Eastern Europe. The aim of the study was to test the hypothesis on the PAH loading differences among urban territories with different land use scenarios. Benzo(a)pyrene toxic equivalency factors (TEFs) were used to calculate BaPeq in order to evaluate carcinogenic risk of soil contamination with PAHs. Results of the study demonstrated that soils within residential and industrial areas are characterized by common loads of PAHs generally attributed to high traffic activity in the city. Considerable levels of soil contamination with PAHs were noted. Total PAH concentrations ranged from 0.33 to 8.10 mg kg−1. A larger portion of high-molecular-weight PAHs along with determined molecular ratios suggest the predominance of pyrogenic sources, mainly attributed to combustion of gasoline, diesel and oil. Petrogenic sources of PAHs have a significant portion and define the predominance of low-molecular-weight PAHs associated with petroleum, such as phenanthrene. Derived concentrations of seven carcinogenic PAHs as well as calculated BaPeq were multiple times higher than reported in a number of other studies. The obtained BaPeq concentrations of the sum of 15 PAHs ranged from 0.05 to 1.39 mg kg−1. A vast majority of examined samples showed concentrations above the safe value of 0.6 mg kg−1 (CCME, 2010). However, estimated incremental lifetime risks posed to the population through distinct routes of exposure were in an acceptable range. One-way ANOVA results showed significant differences in total PAHs and the sum of seven carcinogenic PAH concentrations as well as in levels of FLU, PHE, FLT, PYR, BaA, CHR, BbF, BaP and BPE among parkland, residential and industrial land uses, suggesting the influence of the land use factor.

Bioaccumulation and cancer risk of polycyclic aromatic hydrocarbons in leafy vegetables grown in soils within automobile repair complex and environ in Uyo, Nigeria.

Using gas chromatography-mass spectrometry and an incremental lifetime cancer risks (ILCRs) assessment model, the bioaccumulation and cancer risk of 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs) in leafy vegetables (Vernonia amygdalina and Lasianthera africanum) grown in soils within an automobile repair complex environment in Uyo, Nigeria was studied. The total PAHs concentrations recorded for soils ranged from 0.02 to 1.77mg/kg. The highest level of 1.77mg/kg was recorded for soils from the main automobile repair complex (site 1). Low molecular weight (LMW) PAHs were predominant although some high molecular weight (HMW) PAHs suites (0.04mg/kg of chrysene and 0.04 of benzo[k]fluoranthene) were also found in site 1. The leafy vegetables accumulated PAHs were mostly LMW. Accumulation levels were similar but the extent of PAH uptake in vegetables was species dependent as V. amygdalina accumulated more (0.81mg/kg). The bioaccumulation factors (BaFs) calculated ranged from 0.22 to 0.63 for L. africanum, and 0.18 to 0.55 for V. amygdalina in site 1 where high PAH levels were recorded in soil. Pearson correlation coefficient analysis revealed a strong positive relation between the PAH content of soil and the amount accumulated by L. africanum (r=0.5) and V. amygdalina (r=0.8) at p=0.05. The vegetable's potential to bioaccumulate PAHs is indicative of their use as good bioindicators for PAH contamination in soil. Only two of the USEPA possible human carcinogenic PAHs were detected, and carcinogenic risk assessment based on occupational exposures to soil particles by adults revealed that the total risk level (7.17×10-5) contribution from incidental soil ingestion, dermal contact, and soil particle dust inhalation slightly exceed the USEPA acceptable limits (< 1.00×10-5). There is a need for public education on consumption of vegetables grown in and around automobile repair complexes across Nigeria.

Water-soluble and organic extracts of airborne particulate matter induce micronuclei in human lung epithelial A549 cells

The in vitro genotoxic effects of organic and water-soluble fractions of airborne particulate matter (PM10) with the cytokinesis blocked micronucleus (MN) test in human alveolar carcinoma cells A549 were investigated. Samples were collected in three different sites of São Paulo State, Brazil, and fifteen soluble metals and the sixteen EPÁs priority polycyclic aromatic hydrocarbons (PAH) were chemically determined. PAHs prevailing were fluoranthene and benzo(ghi)perylene. In the water-soluble extracts, highest concentration of metals was found for zinc, iron, and copper in all places of collection. Although PM10 concentration in all samples was in the range of 33.5–110.1μg/m3, lower than 120μg/m3 (limit established by São Paulo State’s legislation for PM10 in 24h), MN results showed that of the 24 samples analyzed, five organic and seven water-soluble extracts presented a significant increase in MN frequency. The frequency of MN correlates with the total PAH concentration of the three sites investigated, and the concentration of PM10 is correlated with the biological effect in two of them. For the water-soluble fraction, all the sites presented a relation between the PM10 concentration and the MN frequency. Again, the genotoxic response showed a correlation with the total concentration of water-soluble metals in two of the three sites. Our results confirm the importance of the soluble fraction of PM10 to the genotoxic effect of airborne PM even at low concentration of water-soluble compounds. Thus, together with chemical analysis, the implementation of the MN protocol for both organic and water-soluble fraction biological monitoring could be used as a strategy in a routine air-quality monitoring program, complementing other usual analyses for air pollution control and protection of populations.

Polycyclic aromatic hydrocarbon contamination in a highly vulnerable underground river system in Chongqing, Southwest China

The concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs) were investigated in the water, sediment and topsoil of the Laolongdong underground river system (LURS) of Chongqing, Southwest China. The total concentrations of PAHs ranged from 81.5 to 8089ng/L in water, from 58.2 to 1070ng/g in sediment, and from 277 to 3301ng/g in topsoil. These levels of PAHs are relatively low compared to other karst areas. Low molecular weight (LMW) PAHs were dominant in water, sediment, topsoil samples, and high molecular weight (HMW) PAHs were more common in topsoil and sediment. The high levels of LMW PAHs in groundwater and sediment suggested relatively recent local sources of PAHs that were transported into the aquifer via wastewater discharge and surface water leakage. The similar composition of PAHs in topsoil and sediment samples suggested that the sediment originated from topsoil and that PAHs in sediment and topsoil had similar origins. The source of PAHs contamination was diagnosed by using PAH isomer ratios and a principal component analysis (PCA) method. The results indicated that PAHs mainly originated from vehicles, coal combustion and petrogenic sources. Significant correlations of PAHs with total organic carbon (TOC) in topsoil and sediment indicated that TOC was an important factor affecting PAHs content.

Polycyclic aromatic hydrocarbon concentrations, compositions, sources, and associated carcinogenic risks to humans in farmland soils and riverine sediments from Guiyu, China

The concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs) were measured in 23 farmland soil samples and 10 riverine sediment samples from Guiyu, China, and the carcinogenic risks associated with PAHs in the samples were evaluated. Guiyu is the largest electronic waste (EW) dismantling area globally, and has been well known for the primitive and crude manner in which EWs are disposed, such as by open burning and roasting. The total PAH concentrations were 56–567 ng/g in the soils and 181–3034 ng/g in the sediments. The Shanglian and Huamei districts were found to be more contaminated with PAHs than the north of Guiyu. The soils were relatively weakly contaminated but the sediments were more contaminated, and sediments in some river sections might cause carcinogenic risks to the groundwater system. The PAHs in the soils were derived from combustion sources, but the PAHs in the sediments were derived from both combustion and petroleum sources.

Parent and halogenated polycyclic aromatic hydrocarbons in farmed cockroaches and implications for human exposure

Medicinal insects have been widely used to cure human diseases for ages. Nevertheless, knowledge about the toxic chemicals accumulated in medicinal insects and their effects on human health was insufficient. In the present study, sixteen priority polycyclic aromatic hydrocarbons (PAHs) and nine halogenated PAHs (HPAHs) were determined in farmed medicinal cockroaches to address this issue. Total concentrations of PAHs in young nymphs, old nymphs, and adults ranged from 162 to 1025, 252 to 967, and 267 to 1168ng/g, respectively. Levels of the sum of HPAHs varied from 0.84 to 9.17, 1.86 to 5.21, and 1.01 to 8.60ng/g for young nymphs, old nymphs, and adults, respectively. The daily intake and excess cancer risk of PAHs and HPAHs were calculated for people who take cockroach-related drugs. Our results indicated that females and children have slightly higher exposure levels from the perspectives of gender and age, respectively. The estimated excess cancer risk of PAHs and HPAHs were both lower than the priority risk level (10-4), indicating a low potential carcinogenic risk with the medicinal cockroach consumption.

Particle-bound PAHs quantification using a 3-stages cascade impactor in French indoor environments

Cascade Impactor is a powerful sampling method to collect airborne particles as a function of their size. The 3-stages Cascade Impactor used in this study allowed to sample simultaneously particles with aerodynamic diameter Dae > 10 μm, 2.5 μm < Dae < 10 μm, 1 μm < Dae < 2.5 μm and Dae < 1 μm. Once collected individual concentrations of the 16 US-EPA priority Polycyclic Aromatic Hydrocarbons (PAHs) bound to particles were quantified for 8 different indoor environments located in Strasbourg area in France. All the heavy PAHs owning between 4 and 6 aromatic rings were detected in all of the 8 sampling sites. The total PAHs concentration varied from 0.44 to 2.09 ng m−3 for a low-energy building school and a smoking apartment, respectively. Results revealed also that high molecular weight PAHs were mainly associated to the finest particles. Our data are consistent with those measured elsewhere in European indoor environments.

Determination and Source Identification of Polycyclic Aromatics Hydrocarbons in Karaj River, Iran

Sixteen priority polycyclic aromatic hydrocarbons (PAHs) were measured in six stations in Karaj River, which is the main resource of drinking water in Tehran. The single PAHs concentrations ranged from not detected to 2,327.8 ng L(-1), with a mean value of 31.5 ng L(-1). The total PAHs concentrations ranged from 25.6, in the spring, to 4,040.3 ng L(-1), in the summer. PAHs concentrations in different sampling stations were similar (p = 0.33-0.99), but strong relationships were detected between seasonal variations and total PAHs, BaP equivalent and carcinogen PAHs concentration (p = 0.010-0.037). Results showed that carcinogen PAHs comprised 7 %-92 % of detected PAHs in different sampling stations. The concentration of benzo(a)pyrene, as an indicator, was lower than the permissible limit of the World Health Organization; however, in some samples, carcinogen PAHs concentrations were higher than the permissible limits of the European Union and USA Environmental Protection Agency regulations for drinking water.

Polycyclic Aromatic Hydrocarbons in drinking water of Tehran, Iran

Distribution and seasonal variation of sixteen priority polycyclic aromatic hydrocarbons (PAHs) were investigated in the drinking water of Tehran, the capital of Iran. Detected single and total PAHs concentrations were in the range of 2.01-38.96 and 32.45-733.10 ng/L, respectively, which were quite high compared to the values recorded in other areas of the world. The average occurrence of PAHs with high molecular weights was 79.55%; for example, chrysene occurred in 60.6% of the samples, with a maximum concentration of 438.96 ng/L. In addition, mean carcinogen to non-carcinogen PAHs ratio was 63.84. Although the concentration of benzo[a]pyrene, as an indicator of water pollution to PAHs, was lower than the guideline value proposed by World Health Organization (WHO) as well as that of Iranian National Drinking Water Standards for all of the samples, the obtained results indicated that carcinogen PAHs present in the drinking water of Tehran can cause threats to human health.

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.