Distributions and concentrations of PAHs in Hong Kong soils

Human health risks of polycyclic aromatic hydrocarbons in the urban soils of Nanjing, China

Polycyclic aromatic hydrocarbons (PAHs) are a major group of toxic pollutants in urban areas. We calculated the critical concentrations of PAHs in the urban soils of Nanjing, China based on a human health risk assessment. In the study area, the risk was divided into four levels and toxic equivalent values of benzo[a]pyrene (BaP_eq) corresponded to <70ngg^-1, 70-700ngg^-1, 700-7000ngg^-1, and >7000ngg^-1. By this standard, most urban areas in Nanjing fall under level II (potentially low risk), while older urban districts, commercial centers, and transportation centers exceed the critical concentration (level III) at present. Additionally, the correlations between PAH concentrations, factors associated with urbanization, and soil properties were analyzed. Population density and black carbon content were determined to be the key factors involved. Multiple linear regression models and the scenario simulation method were used to predict PAH levels in urban soils through 2030. The results indicated that the future distribution characteristics of soil BaP_eq under various scenarios were different than at present, but PAH concentrations remained stable only under the low‑carbon scenario. Therefore, the consumption of traditional fossil fuels should be controlled and replaced with alternative energy sources. In addition, the growth of traffic land use should be controlled in the southern and southwestern parts of the urban area.

Fish as a model to assess chemical toxicity in bone

Environmental toxicology has been expanding as growing concerns on the impact of produced and released chemical compounds over the environment and human health are being demonstrated. Among the toxic effects observed in organisms exposed to pollutants, those affecting skeletal tissues (osteotoxicity) have been somehow overlooked in comparison to hepato-, immune-, neuro- and/or reproductive toxicities. Nevertheless, sub-lethal effects of toxicants on skeletal development and/or bone maintenance may result in impaired growth, reduced survival rate, increased disease susceptibility and diminished welfare. Osteotoxicity may occur by acute or chronic exposure to different environmental insults. Because of biologically and technically advantagous features - easy to breed and inexpensive to maintain, external and rapid rate of development, translucent larvae and the availability of molecular and genetic tools - the zebrafish (Danio rerio) has emerged in the last decade as a vertebrate model system of choice to evaluate osteotoxicity. Different experimental approaches in fish species and analytical tools have been applied, from in vitro to in vivo systems, from specific to high throughput methodologies. Current knowledge on osteotoxicity and underlying mechanisms gained using fish, with a special emphasis on zebrafish systems, is reviewed here. Osteotoxicants have been classified into four categories according to the pathway involved in the transduction of the osteotoxic effects: activation/inhibition of membrane and/or nuclear receptors, alteration of redox condition, mimicking of bone constituents and unknown pathways. Knowledge on these pathways is also reported here as it may provide critical insights into the development, production and release of future chemical compounds with none or low osteotoxicity, thus promoting the green/environmental friendly chemistry.

Baseline concentrations and distributions of Polycyclic Aromatic Hydrocarbons in surface sediments from the Qatar marine environment

Coastal sediments in marine waters of Qatar have the potential of being contaminated by Polycyclic Aromatic Hydrocarbons (PAHs) due to extensive petroleum exploration and transportation activities within Qatar's Marine Exclusive Economic Zone. In this study, the concentration and distribution of sixteen PAHs classed as USEPA priority pollutants were measured in sediments from the eastern Qatari coast. PAHs were recovered from sediments via accelerated solvent extraction and then analyzed using Gas Chromatography-Mass Spectrometry. Total concentrations of the PAHs were in the range of 3.15-14.35μg/kg, and the spatial distribution of PAHs is evaluated in the context of sediment total organic content, depth and the grain size together with and the proximity of petroleum exploration and transportation activities. The data show that the concentrations of PAHs within the study area were in the low-range, suggesting a low risk to marine organisms and limited transfer of PAHs into the food web.

Occurrence of nitro- and oxy-PAHs in agricultural soils in eastern China and excess lifetime cancer risks from human exposure through soil ingestion

The quality of agricultural soil is vital to human health, however soil contamination is a severe problem in China. Polycyclic aromatic hydrocarbons (PAHs) have been found to be among the major soil contaminants in China. PAH derivatives could be more toxic but their measurements in soils are extremely limited. This study reports levels, spatial distributions and compositions of 11 nitrated (nPAHs) and 4 oxygenated PAHs (oPAHs) in agricultural soils covering 26 provinces in eastern China to fill the data gap. The excess lifetime cancer risk (ELCR) from the exposure to them in addition to 21 parent PAHs (pPAHs) via soil ingestion has been estimated. The mean concentration of ∑nPAHs and ∑oPAHs in agricultural soils is 50±45μg/kg and 9±8μg/kg respectively. Both ∑nPAHs and ∑oPAHs follow a similar spatial distribution pattern with elevated concentrations found in Liaoning, Shanxi, Henan and Guizhou. However if taking account of pPAHs, the high ELCR by soil ingestion is estimated for Shanxi, Zhejiang, Liaoning, Jiangsu and Hubei. The maximum ELCR is estimated at ca.10^-5 by both deterministic and probabilistic studies with moderate toxic equivalent factors (TEFs). If maximum TEFs available are applied, there is a 0.2% probability that the ELCR will exceed 10^-4 in the areas covered. There is a great chance to underestimate the ELCR via soil ingestion for some regions if only the 16 priority PAHs in agricultural soils are considered. The early life exposure and burden are considered extremely important to ELCR. Emission sources are qualitatively predicted and for areas with higher ELCR such as Shanxi and Liaoning, new loadings of PAHs and derivatives are identified. This is the first large scale study on nPAHs and oPAHs contamination levels in agricultural soils in China. The risk assessment based on this underpins the policy making and is valuable for both scientists and policy makers.

Distributions and Sources of Polycyclic Aromatic Hydrocarbons (PAHs) in Soils around a Chemical Plant in Shanxi, China

Background: Yearly the Shanxi coal chemical industry extracts many coal resources, producing at the same time many polycyclic aromatic hydrocarbons (PAHs) that are emitted as by-products of coal incomplete combustion. Methods: Sixty-six soil samples collected from 0 to 100 cm vertical sections of three different agricultural (AS), roadside (RS) and park (PS) functional soils around a chemical plant in Shanxi, China were analyzed for the presence of the 16 priority control PAHs. Results: The total concentrations (∑16PAHs) varied in a range of 35.4–116 mg/kg, 5.93–66.5 mg/kg and 3.87–76.0 mg/kg for the RS, PS and AS surface soil, respectively, and 5-ring PAHs were found to be dominant (44.4–49.0%), followed by 4-ring PAHs (15.9–24.5%). Moreover, the average value of ∑16PAHs decreased with the depth, 7.87 mg/kg (0–25 cm), 4.29 mg/kg (25–50 cm), 3.00 mg/kg (50–75 cm), 2.64 mg/kg (75–100 cm) respectively, in PS and AS soil vertical sections. Conclusions: The PAH levels in the studied soils were the serious contamination level (over 1.00 mg/kg) according to the Soils Quality Guidelines. The carcinogenic PAHs (ΣBPAHsBapeq) were approximately 14.8 times higher than the standard guideline level (0.60 mg/kg) and 90.3% of PAHs were produced by coal/wood/grass combustion processes.

Characterisation and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in soils and plants around e-waste dismantling sites in southern China

Environmental pollution due to primitive e-waste dismantling activities has been intensively investigated over the last decade in the south-eastern coastal region of China. In the present study, we investigated the distribution and composition of polycyclic aromatic hydrocarbons (PAHs) in soils and plants around e-waste recycling sites in Longtang, Guangdong province, South China. The results indicated that PAH concentrations in rhizosphere soil and non-rhizosphere soil were in the range of 133 to 626 ng/g and 60 to 816 ng/g, respectively, while PAH levels in plant tissue were 96 to 388 ng/g in shoots and 143 to 605 ng/g in roots. PAHs were enriched in rhizosphere soils in comparison with non-rhizosphere soils. The concentrations of PAHs in plant tissues varied greatly among plant cultivars, indicating that the uptake of PAHs by plants is species-dependent. Different profiles of PAHs in the soil and the corresponding plant tissue implied that PAH uptake and translocation by plants were selective.The total daily intakes of PAHs and carcinogenic PAHs through vegetables at the e-waste recycling site were estimated to be 99 and 22 ng/kg/day, respectively, suggesting that potential health risks associated with the consumption of contaminated vegetables should not be ignored.

Polycyclic aromatic hydrocarbons (PAHs) in Chinese forest soils: profile composition, spatial variations and source apportionment

Previous studies reported that forest ecosystems can play a vital role in scavenging anthropogenic polycyclic aromatic hydrocarbons (PAHs) and act as primary reservoirs of these environmental pollutants. The present study aimed to investigate the occurrence, spatial pattern and source apportionment of PAHs across Chinese background forest soils (O- & A-horizons). The 143 soils collected from 30 mountains showed significantly (p < 0.05) higher levels of ∑₁₅PAHs (ng g⁻¹ dw) in O-horizon (222 ± 182) than A-horizon (168 ± 161). A progressive increase in the levels of lighter PAHs was observed along altitudinal gradient, however heavier PAHs did not show any variations. Carbon contents (TOC & BC) of forest soils were found weakly correlated (p < 0.01) with low molecular weight (LMW)-PAHs but showed no relation with high molecular weight (HMW)-PAHs. Source apportionment results using PMF and PCA revealed that PAHs in forest soils mainly come from local biomass burning and/or coal combustion and attributed that forest soils may become a potential sink for PAHs in the region.

Distribution, sources, and potential risk of polycyclic aromatic hydrocarbons in soils from an industrial district in Shanxi, China

Concentration, composition profile, orientation distribution, sources, and potential risks of 16 polycyclic aromatic hydrocarbons (PAHs) were analyzed in 76 surface (0-25 cm) soil samples collected from the Changzhi industrial district in July 2014 using a gas chromatography mass spectrometer (GC-MS QP2010 Ultra) system. The composition patterns of the PAHs were dominated by the presence of four-ring PAHs (average 42.9%), followed by three-ring (average 25.9%), five-ring PAHs (average 25.6%), two-ring PAHs (average 5.03%), and lastly, six-ring PAHs (average 0.641%). Source apportionment of the soil PAHs was also performed by the diagnostic ratios, principal component analysis (PCA), and coefficient of divergence (CD) analysis indicated signatures of PAHs sources (including incineration, coal/wood combustion, and vehicular exhaust emission). The total concentration of 16 PAHs (∑16PAHs) found in the roadsides soils (RS) ranged from 2197 to 25,041 μg kg^-1, with an arithmetic mean value of 12,245 μg kg^-1; followed by the village soils (VS), which ranged from 2059 to 21,240 μg kg^-1, with a mean of 8976 μg kg^-1; and lastly, the agricultural soils (AS), which ranged from 794 to 16,858 μg kg^-1, with a mean of 3456 μg kg^-1. According to the numerical effect-based soils quality guidelines of Maliszewska-Kordybach, the levels of PAHs in the sampled industrial areas range from high to heavy contamination. The values of total benzo[a]pyrene toxicity equivalent values (∑Bapeq16PAHs) in the sample areas ranged from 0.087 to 3611 μg kg^-1 with an average of 969 μg kg^-1. According to the soil quality guidelines of Canada, values found in the highest range (100 μg kg^-1), which are equal to those of ∑Bapeq16PAHs found in the industrial area samples, will exert adverse biological effects. The results of this research could potentially be useful for local governments to control toxicity exposure, promote actions to alleviate PAHs contamination, and to manage human health at both work and industrial areas.

The impact of selected soil organic matter fractions on the PAH accumulation in the agricultural soils from areas of different anthropopressure

The level of 16PAH accumulation was determined in 75 soil samples collected from two agricultural regions of Poland corresponding to the smallest Polish administrative unit at the LAU 2 level. Both regions are characterised by similar territory and soil cover but different history of pollution and different pressure of anthropogenic factors. Overall accumulation of Σ16PAHs in the upper soil layer was within a wide range with the median value of 291 and 1253 μg kg^-1 for a non-contaminated and high anthropopressure region, respectively. Nearly 75 % of the total polycyclic aromatic hydrocarbon (PAH) pool was represented by high molecular four-to-six-ring compounds, deriving mainly from combustion sources. The total organic carbon (C_org) and black carbon (BC) contents were the main parameters associated with the PAH accumulation in soils, and the level of the regional anthropopressure was considered a significant factor. The strongest links of PAHs/BC (r = 0.70, p ≤ 0.05) were found in the region of high anthropopressure, characterized by a relatively high content of BC (up to 45.3 g kg^-1), which tends to heavily adsorb hydrocarbons. In a region of low influence exerted by anthropopressure, the PAH/C_org or PAH/BC relationships were not observed, which may suggest different diffuse sources of PAH origin and a dominant role of other organic matter fractions in retention of PAHs in soils.

Polycyclic aromatic hydrocarbons (PAHs) in water and sediment from a river basin: sediment-water partitioning, source identification and environmental health risk assessment

The information on concentration levels, partitioning and sources of pollutants in aquatic environment is quite necessary for pollution treatment and quality criteria. In this work, sixteen priority polycyclic aromatic hydrocarbons (PAHs) recommended by U.S. Environmental Protection Agency in the water and sediment of Yinma River Basin were firstly investigated. Among 16 individual PAHs, naphthalene was the highest average concentration in water samples as well as in sediment samples, 67.2 ng/L and 825.06 ng/g, respectively, whereas benzo(g,h,i)perylene was undetected in water samples nor in sediment samples. For three PAH compositional patterns, concentrations of light (2-3 ring) PAHs were dominant in water and sediment, accounting for 71.69 and 86.98 % respectively. The PAH partitioning in the sediment-water system was studied, results showed that PAH partitioning was in an unsteady state and tended to accumulate in the sediment. The possible sources of PAHs in water and sediment were both identified as a mixed source of petroleum and combustion. The benzo(a)pyrene equivalents (EBaP) values for PAHs in the water and sediment in some sites were relatively higher, suggesting the existence of environmental health risk.

Remediation approaches for polycyclic aromatic hydrocarbons (PAHs) contaminated soils: Technological constraints, emerging trends and future directions

For more than a decade, the primary focus of environmental experts has been to adopt risk-based management approaches to cleanup PAH polluted sites that pose potentially destructive ecological consequences. This focus had led to the development of several physical, chemical, thermal and biological technologies that are widely implementable. Established remedial options available for treating PAH contaminated soils are incineration, thermal conduction, solvent extraction/soil washing, chemical oxidation, bioaugmentation, biostimulation, phytoremediation, composting/biopiles and bioreactors. Integrating physico-chemical and biological technologies is also widely practiced for better cleanup of PAH contaminated soils. Electrokinetic remediation, vermiremediation and biocatalyst assisted remediation are still at the development stage. Though several treatment methods to remediate PAH polluted soils currently exist, a comprehensive overview of all the available remediation technologies to date is necessary so that the right technology for field-level success is chosen. The objective of this review is to provide a critical overview in this respect, focusing only on the treatment options available for field soils and ignoring the spiked ones. The authors also propose the development of novel multifunctional green and sustainable systems like mixed cell culture system, biosurfactant flushing, transgenic approaches and nanoremediation in order to overcome the existing soil- contaminant- and microbial-associated technological limitations in tackling high molecular weight PAHs. The ultimate objective is to ensure the successful remediation of long-term PAH contaminated soils.

Source and Ecological Risk Characteristics of PAHs in Sediments from Qinhuai River and Xuanwu Lake, Nanjing, China

In order to investigate the residual characteristics, sources, and ecological risk of PAHs in sediment from urban rivers, the sediments of 15 typical sites from Qinhuai River and Xuanwu Lake, which are typical urban rivers and lake, were collected from October 2015 to July 2016; the sources of PAHs in sediment were also identified by several methods. Results showed that ∑PAHs concentration in sediment ranged from 796.2 ng/g to 10,470 ng/g with an average of 2,713.8 ng/g. High molecular weight PAHs with 4-5 rings were most prominent in the sediment during all four seasons. Source characterization studies based on the analysis of diagnostic ratio (triangular plot method), cluster analysis, and positive factor matrix analysis suggested that the PAHs of Qinhuai River Basin were mainly from pyrogenic origin (biomass and coal combustion and vehicular emission), and the petroleum source also cannot be ignored (specially in summer). Most individual PAHs occasionally affect the aquatic organisms. The highest benzo[a]pyrene-equivalent doses (BaPeq dose) appear at the sites of sewage discharge and heavy traffic. So, the PAHs pollution sources of urban water body have obvious seasonal-dependent and human activities-dependent characteristics.

Spatial distribution and source apportionment of PAHs in marine surface sediments of Prydz Bay, East Antarctica

This paper reports the concentrations of polycyclic aromatic hydrocarbons (PAHs) in marine sediments sampled from Prydz Bay, East Antarctica. Total PAH concentrations ranged from 12.95 to 30.93 ng/g, with a mean of 17.99 ± 5.57 ng/g. Two- and three-ring PAHs were the most abundant compounds found at the majority of the sampling stations of Prydz Bay. Long-range atmospheric transportation was found to play an important role in determining the spatial distribution of PAHs in the sediments sampled here. However, transport by ocean currents and release from melting glaciers were also found to influence PAH distributions in the sediments of East Antarctica. The vertical migration of PAHs in sediments showed a decreasing trend with depth, with higher concentrations in the relatively shallow-water regions (<500 m) found on the Fram and Four Ladies banks compared with those of the intermediate-depth (500-1000 m) and deep-water regions (>1000 m) of the Amery Basin and associated Canyons, respectively. A Pearson correlation analysis between PAH concentrations and sediment parameters demonstrated that PAHs has poor correlations with grain size, but has positive correlation with total organic carbon, indicated complex processing during transfer to remote environments. The results of qualitative and quantitative analyses indicate that the PAHs sampled here were derived mainly from a mixture of biomass combustion, traffic emissions, and petrogenic sources.

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.

Carcinogenic and endocrine-disrupting PAHs in the aquatic ecosystem of India

The quantification studies of 17 carcinogenic and endocrine-disrupting polycyclic aromatic hydrocarbons (PAHs) in the Mithi River polluting the Mahim Creek near Mumbai were performed to understand their sources and probable ecological risk. The overall concentration level of ΣPAHs was 157.96 ± 18.99 μg L^-1, while that of carcinogenic PAHs (ΣC-PAHs) was 81.31 ± 9.75 μg L^-1, which corresponds to 51.5 % of the ΣPAHs. The source analysis of PAH pollution was made on the basis of different PAH ratios. It was observed that the probable PAH contamination was due to pyrogenic inputs arising due to the combustion of grass, wood, and coal as well as due to the combustion of diesel and gasoline. Toxicity and biological risk assessment was made using toxic equivalent quantity (TEQ) for various C-PAHs. The results of our study showed that the mean BaP concentration in the Mithi River water (8.61 μg L^-1) was above the European Directive 2008/105/EC Environmental Quality Standards (EQS) value of 0.05 μg L^-1, while the levels of benzo(k)fluoranthene (BkF) + benzo(b)fluoranthene (BbF) (21.54 μg L^-1) and benzo(g,h,i)perylene (BghiP) + indeno(1,2,3,-c,d) pyrene (InP) (18.27 μg L^-1) were significantly higher than that set by the EQS (0.03 and 0.002 μg L^-1, respectively), showing that the ecological integrity of the river and the adjoining creek is possibly at risk.

PAH contamination in Beijing's topsoil: A unique indicator of the megacity's evolving energy consumption and overall environmental quality

To improve its air quality, Beijing, the capital of China, has implemented high-cost pollution control measures mainly focused on shifting its energy mix. However, the effectiveness of these measures has long been questioned, especially given the recent problem of severe haze. The main study objectives are to achieve independent, although indirect, information on Beijing's air pollution by measuring the level of polycyclic aromatic hydrocarbon (PAH) contamination in topsoil and to examine how soil contamination reflects energy consumption. Soil sampling data from two years, 2004 and 2013, were used. The key findings are as follows: 1) although the total PAH content in the topsoil did not significantly decrease from 2004 to 2013, the composition changed considerably; 2) as of 2013, vehicle emissions replaced coal combustion as the leading source of soil PAHs, which validates the existing policy measures regarding vehicle purchasing and traffic volume; 3) the regional transport of atmospheric pollutants, as indicated by the contribution of coking sources in 2013, is not negligible; and 4) appropriate policy measures are needed to control the growing practice of burning biomass. Overall, this study demonstrates that the PAH contamination in topsoil represents an informative indicator of Beijing's energy consumption and overall environmental quality.

Distribution pattern and the risks of OPCs, PHAs and PCBs in aged refuses from landfill

Persistent organic pollutants (POPs) are the urgent risk for landfill, and should be considered before the landfill reclamation and resource. In this work, the distribution pattern of selected POPs in landfill and their ecological risks were investigated and assessed. The Σ20OCPs, Σ16PAHs and Σ19PCBs were around 157.4-329.2, 4103-19,190, and 79.1-340.3μgkg(-1) in aged refuses, with the mean value of 206.6, 8645.4, and 155.1μgkg(-1). While those in soil covers were only 6.3-75.4, 125.5-515.3 and 2.6-43.4μgkg(-1), with the mean value of 33.7, 257.7, and 24.0μgkg(-1), respectively. The maximum OPCs, PHAs and PCBs were in aged refuse with 13, 7, 10 disposal years. Whereas, the corresponding top content in soil covers were in 10, 13 and 16years, meaning that aged refuses were not the direct source for soil covers. Among 20 OCPs measured, α-HCH, δ-HCH, Dieldrin, and Endrin were presented in all aged refuses, with the mean concentration of 93.6, 52.1, 3.9 and 4.7μgkg(-1), respectively. For PAHs, PHE, FLU and PYR were the main composition, and reached to 1535, 1224, 1187μgkg(-1). The Σ7CarPAHs occupied around 33.3-49.9% of total Σ16PAHs tested, and could be used as the indictor for PAHs pollutant in landfill. PCB-5 content was around 40.7-263.3μgkg(-1) in aged refuses, and occupied around 51.5-81.8% of Σ19PCBs measured. The HCHs and DDTs in aged refuses were below the national standard GB15618-1995, and the corresponding Σ19PCBs concentrations met the standard of GB 13015-91, suggesting that aged refuse are accepted for the further utilization process.

Characterizing polycyclic aromatic hydrocarbon build-up processes on urban road surfaces

Reliable prediction models are essential for modeling pollutant build-up processes on urban road surfaces. Based on successive samplings of road deposited sediments (RDS), this study presents empirical models for mathematical replication of the polycyclic aromatic hydrocarbon (PAH) build-up processes on urban road surfaces. The contaminant build-up behavior was modeled using saturation functions, which are commonly applied in US EPA's Stormwater Management Model (SWMM). Accurate fitting results were achieved in three typical urban land use types, and the applicability of the models was confirmed based on their acceptable relative prediction errors. The fitting results showed high variability in PAH saturation value and build-up rate among different land use types. Results of multivariate data and temporal-based analyses suggested that the quantity and property of RDS significantly influenced PAH build-up. Furthermore, pollution sources, traffic parameters, road surface conditions, and sweeping frequency could synthetically impact the RDS build-up and RDS property change processes. Thus, changes in these parameters could be the main reason for variations in PAH build-up in different urban land use types.

Spatial distribution and temporal trends of farmland soil PBDEs: processes and crop rotation effects

The concentration and temporal trend of PBDEs in farmland soil during a circle of crop rotation period within an e-waste dismantling area of South China were investigated. The averaged current concentration of total PBDEs in the farmland soil was averaged 19.1 ± 20.7 ng/g dry weight, which was much lower than the PBDE level in roadside soil and in topsoil near e-waste dismantling sites. Spatial distribution of total PBDEs concentration in the study area showed higher level at the field near e-waste workshops and lower at the distanced farmland area. Soil organic carbon content was significantly correlated with concentration of BDE209 (r = 0.704, p < 0.01), but not related with the sum concentration of other PBDE compounds (r = 0.097, p > 0.1). During the whole crop rotation circle, the temporal concentration of PBDEs in the farmland soil was highest (25.3 ± 11.4 ng/g dry wt.) in April when early paddy had been transplanted for 1 or 2 weeks. When the crop rotated to autumn peanut in August and the land is turning dry, the PBDEs concentration in farmland soil reached the lowest level which was 8.1 ± 1.2 ng/g dry wt. The temporal trend of PBDEs in farmland soil was not consistent with that of atmospheric PBDEs and soil total organic carbon (TOC) content during the rotation cycle. It was concluded that the dynamics of PBDEs in the farmland soil is influenced by multiple, interacting factors, and not clearly related to neither the atmospheric deposition nor the organic carbon content of the soil, but possibly related to the micro-environmental conditions changed by crop rotation process.

Status of POPs accumulation in the Yellow River Delta: From distribution to risk assessment

The Yellow River Delta (YRD) is a large region of China with complex pollution sources and a long history of environmental deterioration. Despite this, relatively little data exists on the status of important contaminants of concern in this region. Here, we review the literature on the status of key persistent organic pollutants (POPs) of concern including organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) in the YRD. Sources, source identification methods, and spatial distribution patterns are presented. Additionally, POPs contamination levels reported in the literature were evaluated against popular regulatory limits worldwide to form a basis for overall environmental health. Our review determined that OCPs in the YRD originated mainly from current pesticide use and past agricultural pesticide application. Sources of PAHs included petrochemical inputs, coal fired plants, and wood combustion. PCB levels were impacted by the petrochemical industry as well as waste disposal of PCB containing equipment. OCPs exhibited a spatial distribution pattern that increased along the urban-rural gradient, while the opposite was seen for PAHs and PCBs. Comparisons of POPs contamination levels in the YRD with popular regulatory limits suggest that the extent of PCB contamination all mediums (sediment, soil, water, and biota) exceeded that of PAHs and OCPs. Overall pollution levels in the YRD seem to be in control; however, levels from heavily polluted point sources raise numerous concerns about the ecological health of the region and require more attention from regulatory authorities.

Concentration profiles, source apportionment and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in dumpsite soils from Agbogbloshie e-waste dismantling site, Accra, Ghana

The concentrations of eighteen (18) polycyclic aromatic hydrocarbons (PAHs), including the 16 USEPA's priority PAHs as well as two alkyl-substituted naphthalenes were determined in dumpsite soils collected from different sampling sites within the Agbogbloshie e-waste dismantling site in Accra, Ghana. Following their isolation with ultrasonic-assisted extraction technique, the concentrations of the PAHs were determined by gas chromatography mass spectrometry (GC-MS). Loss-on-ignition (LOI) method was employed for the determination of total organic carbon (TOC) of the soil samples. The mean Σ18PAHs obtained were 3006, 5627, 3046, 5555, and 7199 ng g(-1) dry weight (dw) for sampling sites A (mosque), B (dismantling site), C (residential house/police station), D (personal computer repairers' shop) and E (e-waste open burning area), respectively. In all cases, the prevalence of phenanthrene, fluoranthene and pyrene was generally observed across the sampling sites. In this study, PAHs with two to three rings and four to six rings exhibited strong positive correlations, whereas BbF and BkF showed weak positive and negative correlations with other PAHs investigated. With the exception of BbF and BkF, all the PAHs had moderate to strong positive correlations with the TOC. Benzo[a]pyrene equivalent (BaPeq) concentration is a useful indicator of the carcinogenic potency of environmental matrices and these ranged between 111 and 454 ng g(-1), which are generally below the 'safe' level of 600 ng g(-1) established for the protection of the environment and human health. Interestingly, the seven carcinogenic PAHs were the major contributors to the BaPeq concentrations accounting between 97.7 and 98.3 %. Despite the minimal risk to cancer via exposure to the investigated dumpsite soil as indicated in the present study, the prolonged exposure to these pollutants via various exposure pathways may result in increased risk to cancer over time. The application of several methodological approaches for PAH source apportionment, including the use of molecular diagnostic ratios, mostly implicated pyrogenic processes as the main sources of PAHs into the investigated dumpsite soils. Furthermore, their compositional profiles across the sampling sites also suggest similar sources of PAHs into the dumpsite soil.

Polycyclic Aromatic Hydrocarbons in Sediments and Bivalves on the Pacific Coast of Japan: Influence of Tsunami and Fire

Surface sediments and at least one edible bivalve species (Ruditapes philippinarum, Mytilus galloprovincialis, and Crassostrea gigas) were collected from each of seven intertidal sites in Japan in 2013. The sites had experienced varying levels of tsunami and fire disturbance following the major earthquake of 2011. Eight polycyclic aromatic hydrocarbons (PAHs) were identified and analyzed by gas chromatography–mass spectrometry. Total sediment PAH concentration (C_T), the sum of the average concentrations of the eight PAHs, was 21–1447 μg kg^-1-dry. Relative to the average level of one type of PAH in sediments collected around Japan in 2002 (benzo[a]pyrene = 21 μg kg^-1-dry), five of the seven sites showed concentrations significantly lower than this average in 2013. The C_Ts for the three bivalves (134–450 μg kg^-1-dry) were within the range of the previous reports (2.2–5335 μg kg^-1-dry). The data suggest that the natural disaster did not increase PAH concentrations or affect the distribution within sediment or bivalves in Tohoku district. Although PAH concentrations at the sites pose no risk to human health, the findings highlight that the observed PAH levels derive from pre- rather than post-quake processes.

Bacteria capable of degrading anthracene, phenanthrene, and fluoranthene as revealed by DNA based stable-isotope probing in a forest soil

Information on microorganisms possessing the ability to metabolize different polycyclic aromatic hydrocarbons (PAHs) in complex environments helps in understanding PAHs behavior in natural environment and developing bioremediation strategies. In the present study, stable-isotope probing (SIP) was applied to investigate degraders of PAHs in a forest soil with the addition of individually (13)C-labeled phenanthrene, anthracene, and fluoranthene. Three distinct phylotypes were identified as the active phenanthrene-, anthracene- and fluoranthene-degrading bacteria. The putative phenanthrene degraders were classified as belonging to the genus Sphingomona. For anthracene, bacteria of the genus Rhodanobacter were the putative degraders, and in the microcosm amended with fluoranthene, the putative degraders were identified as belonging to the phylum Acidobacteria. Our results from DNA-SIP are the first to directly link Rhodanobacter- and Acidobacteria-related bacteria with anthracene and fluoranthene degradation, respectively. The results also illustrate the specificity and diversity of three- and four-ring PAHs degraders in forest soil, contributes to our understanding on natural PAHs biodegradation processes, and also proves the feasibility and practicality of DNA-based SIP for linking functions with identity especially uncultured microorganisms in complex microbial biota.

Linking mobile source-PAHs and biological effects in traffic police officers and drivers in Rawalpindi (Pakistan)

The aim of this study was to evaluate the effect of traffic related polycyclic aromatic hydrocarbons (PAHs) on blood parameters of subjects, including traffic police officers (TP), drivers (DR) and control subjects (CN) with presumably different levels of exposure. We quantified the urinary 1-hydroxypyrene (1-OHPyr), α-naphthol and β-naphthol (α- and β-naph) as biomarkers of exposure to PAHs in relation with biomarkers of effect (Hb, MCV, PCV, PLT, RBCs), biomarkers of inflammation/infection (CRP, WBCs), oxidative stress (SOD) and oxidative DNA damage i.e. 8-hydroxy-2-deoxyguanosine (8-OHdG). Results showed that mean 1-OHPyr, α-naph and β-naph concentrations were significantly higher in TPs (0.98, 1.55, and 1.9µmolmol-Cr(-1), respectively, p<0.05) than CNs (0.7, 0.6; 0.67µmolmol-Cr(-1), respectively, P<0.05). Furthermore, WBC and CRP were found in higher concentrations in TPs than CNs (7.04×10(3)µL(-1) and 0.95mgL(-1) vs. 5.1×10(3)µL(-1) and 0.54mgL(-1), respectively). The urinary 8-OHdG level, a biomarker of oxidative DNA damage, was higher in TPs than both CN and DR subjects (48ngmg-Cr(-1), 24ngmg-Cr(-1) and 33ngmg-Cr(-1), respectively). Self-reported health assessment indicates that, on the basis of daily time spent in the middle of heavy traffic, TPs and DRs more frequently suffered from adverse head and respiratory symptoms. The PCA analysis evidenced the impact of traffic pollution on exposure biomarkers and DNA damage. The study suggests that traffic pollution may be associated with important health risk, in particular on the respiratory system, not only for workers exposed to traffic exhausts but also for general public. Finally, vehicular air pollution in the city of Rawalpindi should be a high-priority concern for the Pakistan Government that needs to be addressed.

Spatial Distribution of Polycyclic Aromatic Hydrocarbon (PAH) Concentrations in Soils from Bursa, Turkey

The objectives of this study were to identify regional variations in soil polycyclic aromatic hydrocarbon (PAH) contamination in Bursa, Turkey, and to determine the distributions and sources of various PAH species and their possible sources. Surface soil samples were collected from 20 different locations. The PAH concentrations in soil samples were analyzed using gas chromatography-mass spectrometry (GC-MS). The total PAH concentrations (∑12 PAH) varied spatially between 8 and 4970 ng/g dry matter (DM). The highest concentrations were measured in soils taken from traffic+barbecue+ residential areas (4970 ng/g DM) and areas with cement (4382 ng/g DM) and iron-steel (4000 ng/g DM) factories. In addition, the amounts of ∑7 carcinogenic PAH ranged from 1 to 3684 ng/g DM, and between 5 and 74 % of the total PAHs consisted of such compounds. Overall, 4-ring PAH compounds (Fl, Pyr, BaA and Chr) were dominant in the soil samples, with 29-82 % of the ∑12 PAH consisting of 4-ring PAH compounds. The ∑12 BaPeq values ranged from 0.1 to 381.8 ng/g DM. Following an evaluation of the molecular diagnostic ratios, it was concluded that the PAH pollution in Bursa soil was related to pyrolytic sources; however, the impact of petrogenic sources should not be ignored.

Lagdo Dam Flood Disaster of 2012: An Assessment of the Concentrations, Sources, and Risks of PAHs in Floodplain Soils of the Lower Reaches of River Niger, Nigeria

The concentrations of the USEPA 16 priority polycyclic aromatic hydrocarbons (PAHs) in soils of the floodplain of the lower reaches of River Niger, Nigeria, were investigated following the Lagdo Dam flood disaster of 2012. The aim was to provide information on the extent of contamination, sources, and risks of PAHs in these soils. The concentrations of Σ16 PAHs in the floodplain soils ranged from 812 to 10,700 μg kg. The benzo(a)pyrene (BaP) toxic equivalence and incremental lifetime cancer risk (ILCR) factors were used to evaluate the risk of human exposure to PAHs in these soils. The concentrations of benzo(a)pyrene carcinogenic equivalence (BaP) and benzo(a)pyrene mutagenic equivalence (BaP) ranged from not detected to 4090 μg kg and not detected to 4150 μg kg, respectively. The total ILCR for children and adults was calculated as the summation of the individual risks through the three routes of exposure, (ingestion, dermal, and inhalation of vapor or dust). The values obtained indicate that there are 6450 and 4480 chances in one million equally exposed persons to develop the risk of cancer for children and adults, respectively, which were higher than the USEPA acceptable guideline value of one cancer case in one million (10) equally exposed persons. The PAHs source evaluation, using the diagnostic ratios and principal component analysis (PCA), indicated that the major sources of PAHs in these soils were fossil fuel combustion, gas flaring, wood combustion, traffic emissions, and input from petroleum.

Removal of polycyclic aromatic hydrocarbons (PAHs) from inorganic clay mineral: Bentonite

There has been limited study of the removal of polycyclic aromatic hydrocarbons (PAHs) from inorganic clay minerals. Determining the amount of PAH removal is important in predicting their environmental fate. This study was carried out to the degradation and evaporation of PAHs from bentonite, which is an inorganic clay mineral. UV apparatus was designed specifically for the experiments. The impacts of temperature, UV, titanium dioxide (TiO2), and diethylamine (DEA) on PAH removal were determined. After 24 h, 75 and 44 % of ∑12 PAH in the bentonite were removed with and without UV rays, respectively. DEA was more effective as a photocatalyst than TiO2 during UV application. The ∑12 PAH removal ratio reached 88 % with the addition of DEA to the bentonite. It was concluded that PAHs were photodegraded at high ratios when the bentonite samples were exposed to UV radiation in the presence of a photocatalyst. At the end of all the PAH removal applications, higher evaporation ratios were obtained for 3-ring compounds than for heavier ones. More than 60 % of the amount of ∑12 PAH evaporated consisted of 3-ring compounds.

Insight into the transgenerational effect of benzo[a]pyrene on bone formation in a teleost fish (Oryzias latipes)

Recent cross-generational studies in teleost fish have raised the awareness that high levels of benzo[a]pyrene (BaP) could affect skeletal integrity in the directly exposed F0 and their F1-F2. However, no further details were provided about the causes for abnormalities on the molecular and cellular level and the persistence of such sub-organismal impairments at the transgenerational scale (beyond F2). Adult Oryzias latipes were exposed to 1μg/L BaP for 21days. The F1-F3 were examined for skeletal deformities, histopathological alterations of vertebral bodies and differential expression of key genes of bone metabolism. Significant increase of dorsal-ventral vertebral compression was evident in ancestrally exposed larvae. Histopathological analysis revealed abnormal loss of notochord sheath, a lack of notochord epithelial integrity, reduced bone tissue and decreased osteoblast abundance. A significant downregulation of ATF4 and/or osterix and a high biological variability of COL10, coupled with a significant deregulation of SOX9a/b in the F1-F3 suggest that ancestral BaP exposure most likely perturbed chordoblasts, chondroblast and osteoblast differentiation, resulting in defective notochord sheath repair and rendering the vertebral column more vulnerable to compression. The present findings provide novel molecular and cellular insights into BaP-induced transgenerational bone impairment in the unexposed F3. From the ecological risk assessment perspective, BaP needs to be regarded as a transgenerational skeletal toxicant, which exerts a far-reaching impact on fish survival and fitness. Given that basic mechanisms of cartilage/bone formation are conserved between medaka and mammals, the results may also shed light on the potential transgenerational effect of BaP on the genesis of skeletal diseases in humans.

Human Health and Ecological Risk Assessment of 16 Polycyclic Aromatic Hydrocarbons in Drinking Source Water from a Large Mixed-Use Reservoir

Reservoirs play an important role in living water supply and irrigation of farmlands, thus the water quality is closely related to public health. However, studies regarding human health and ecological risk assessment of polycyclic aromatic hydrocarbons (PAHs) in the waters of reservoirs are very few. In this study, Shitou Koumen Reservoir which supplies drinking water to 8 million people was investigated. Sixteen priority PAHs were analyzed in a total of 12 water samples. In terms of the individual PAHs, the average concentration of Fla, which was 5.66 × 10⁻¹ μg/L, was the highest, while dibenz(a,h)anthracene which was undetected in any of the water samples was the lowest. Among three PAH compositional patterns, the concentration of low-molecular-weight and 4-ring PAHs was dominant, accounting for 94%, and the concentration of the total of 16 PAHs was elevated in constructed-wetland and fish-farming areas. According to the calculated risk quotients, little or no adverse effects were posed by individual and complex PAHs in the water on the aquatic ecosystem. In addition, the results of hazard quotients for non-carcinogenic risk also showed little or no negative impacts on the health of local residents. However, it could be concluded from the carcinogenic risk results that chrysene and complex PAHs in water might pose a potential carcinogenic risk to local residents. Moreover, the possible sources of PAHs were identified as oil spills and vehicular emissions, as well as the burning of biomass and coal.

Polycyclic aromatic hydrocarbons (PAHs) in atmospheric dustfall from the industrial corridor in Hubei Province, Central China

Thirty atmospheric dustfall samples collected from an industrial corridor in Hubei Province, central China, were analyzed for 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs) to investigate their concentrations, spatial distributions, sources, and health risks. Total PAH concentrations (ΣPAHs) ranged from 1.72 to 13.17 µg/g and averaged 4.91 µg/g. High molecular weight (4-5 rings) PAHs averaged 59.67% of the ΣPAHs. Individual PAH concentrations were not significantly correlated with total organic carbon, possibly due to the semi-continuous inputs from anthropogenic sources. Source identification studies suggest that the PAHs were mainly from motor vehicles and biomass/coal combustion. The incremental lifetime cancer risks associated with exposure to PAHs in the dustfall ranged from 10(-4) to 10(-6); these indicate potentially serious carcinogenic risks for exposed populations in the industrial corridor.

Polycyclic aromatic hydrocarbons in soils from urban to rural areas in Nanjing: Concentration, source, spatial distribution, and potential human health risk

Polycyclic aromatic hydrocarbons (PAHs) have become a major type of pollutant in urban areas and their degree of pollution and characteristics of spatial distribution differ between various regions. We conducted a comprehensive study about the concentration, source, spatial distribution, and health risk of 16 PAHs from urban to rural soils in Nanjing. The mean total concentrations of 16 PAHs (∑16PAHs) were 3330 ng g(-1) for urban soils, 1680 ng g(-1) for suburban soils, and 1060 ng g(-1) for rural soils. Five sources in urban, suburban, and rural areas of Nanjing were identified by positive matrix factorization. Their relative contributions of sources to the total soil PAH burden in descending order was coal combustion, vehicle emissions, biomass burning, coke tar, and oil in urban areas; in suburban areas the main sources of soil PAHs were gasoline engine and diesel engine, whereas in rural areas the main sources were creosote and biomass burning. The spatial distribution of soil PAH concentrations shows that old urban districts and commercial centers were the most contaminated of all areas in Nanjing. The distribution pattern of heavier PAHs was in accordance with ∑16PAHs, whereas lighter PAHs show some special characteristics. Health risk assessment based on toxic equivalency factors of benzo[a]pyrene indicated a low concentration of PAHs in most areas in Nanjing, but some sensitive sites should draw considerable attention. We conclude that urbanization has accelerated the accumulation of soil PAHs and increased the environmental risk for urban residents.

Polycyclic aromatic hydrocarbons (PAHs) and their derivatives (alkyl-PAHs, oxygenated-PAHs, nitrated-PAHs and azaarenes) in urban road dusts from Xi'an, Central China

Urban road dusts are carriers of polycyclic aromatic compounds (PACs) and are therefore considered to be a major source of contamination of other environmental compartments and a source of exposure to PACs for urban populations. We determined the occurrence, composition pattern and sources of several PACs (29 alkyl- and parent-PAHs, 15 oxygenated-PAHs (OPAHs), 4 azaarenes (AZAs), and 11 nitrated-PAHs (NPAHs)) in twenty urban road dusts and six suburban surface soils (0-5cm) from Xi'an, central China. The average concentrations of ∑29PAHs, ∑4AZAs, ∑15OPAHs, and ∑11NPAHs were 15767, 673, 4754, and 885 n gg(-1) in road dusts and 2067, 784, 854, and 118 ng g(-1) in surface soils, respectively. The concentrations of most individual PACs were higher in street dusts than suburban soils, particularly for PACs with molecular weight>192 g mol(-1). The enrichment factors of individual PACs were significantly positively correlated with log KOA and log KOW, indicating an increasing deposition and co-sorption of the PACs in urban dusts with decreasing volatility and increasing hydrophobicity. Significant correlations between the concentrations of individual and sum of PACs, carbon fractions (soot and char), and source-characteristic PACs (combustion-derived PAHs and retene, etc.), indicated that PAHs, OPAHs and AZAs were mostly directly emitted from combustion activities and had similar post-emission fates, but NPAHs were possibly more intensely photolyzed after deposition as well as being emitted from vehicle exhaust sources. The incremental lifetime cancer risk (ILCR) resulting from exposure to urban dust bound-PACs was higher than 10(-6), indicating a non-negligible cancer risk to residents of Xi'an.

Spatial distribution of polycyclic aromatic hydrocarbons in soil, sediment, and combusted residue at an e-waste processing site in southeast China

The environmental pollution and health impacts caused by the primitive and crude recycling of e-waste have become urgent global issues. Guiyu, China is a major hotspot of e-waste recycling. In this study, the levels and distribution of polycyclic aromatic hydrocarbons in soil in Guiyu were determined to investigate the effect of e-waste activities on the environment and to identify possible sources of these pollutants. Sediment samples from a local duck pond, water gullies, a river tributary, and combusted residue from e-waste burning sites were also investigated. The general trend found in soil (Σ16 PAHs) was acid leaching site > duck pond > rice field > printer roller dump site > reservoir (control site) and ranged from 95.2 ± 54.2 to 5,210 ± 89.6 ng/g (dry wt). The highest average total PAH concentrations were found in combusted residues of wires, cables, and other computer electrical components located at two e-waste open burning sites (18,600 and 10,800 ± 3,940 ng/g). These were 195- and 113-fold higher than the PAH concentrations of soil at the control site. Sediment PAH concentrations ranged from 37.2 ± 6 to 534 ± 271 ng/g. Results of this study provide further evidence of significant input of PAHs to the environment attributed to crude e-waste recycling.

Distribution and source apportionment of polycyclic aromatic hydrocarbons in the surface soil of Baise, China

To estimate the distribution and sources of polycyclic aromatic hydrocarbons (PAHs) in the soils of Baise, in southwest China, soil sampling sites were selected from industry, traffic, rubbish, gas station, residential, and suburban areas for analysis of PAHs. The average concentrations of ∑16PAHs in the present study varied significantly, depending on the sampling location, and ranged from 16.8 to 6,437.0 μg/kg (dry weight basis), with a mean value of 565.8 μg/kg. PAH concentrations decreased significantly along the industry-traffic-rubbish-gas station-residential-suburban transect. The PAH profiles in the surface soil of the different areas imply that either source proximity to the sampling sites, or transport and deposition effects influenced PAH distributions. Two diagnostic ratios were selected and used to apportion PAH sources in the surface soil, and bivariate plots show general trends of covariation. Principal component analysis and multivariate linear regression were used to determine the primary sources and their contributions of PAHs to the soils. The model showed that factors 1 (coal and wood combustion) and 2 (petroleum combustion) contributed over 52.1 and 32.5% of the total source of soil PAHs, respectively. The remaining 15.4% came from evaporative and uncombusted petroleum.

Distribution of polycyclic aromatic hydrocarbons in surface sediments of lower reaches of the Don River (Russia) and their ecotoxicologic assessment by bacterial lux-biosensors

The lower Don River in the south of the European part of Russia was studied to determine the concentration, spatial distribution, and sources of 19 polycyclic aromatic hydrocarbons (PAHs) in surface sediments. Total PAH concentrations ranged from 14.2 to 529 ng/g-dw. Sedimentary PAH concentrations were higher in the delta of the Don River and in the estuaries of rivers Sal and Aksai compared to the main channel of the Don. Analysis of the PAHs sources showed that PAHs came mostly from pyrogenic sources as a result of incomplete combustion of coal. Bioluminescent bacterial sensors were used for ecotoxicological assessment of surface sediments. The surface sediments of all the investigated stations of lower reaches of the Don River were toxic and genotoxic. The maximum concentration of PAHs and the high genotoxicity effect caused by the presence of genotoxicants were found in the surface sediments of the same stations. Significant correlations between the concentrations of individual PAHs in sediments and the genotoxic effect were found. Correlation between genotoxicity of surface sediments and concentration of phenanthrene and benz(k)fluoranthene was the most significant both with and without application of metabolic activation.

Polycyclic aromatic hydrocarbons associated with total suspended particles and surface soils in Kunming, China: distribution, possible sources, and cancer risks

The concentrations, distribution, possible sources, and cancer risks of polycyclic aromatic hydrocarbons (PAHs) in total suspended particles (TSPs) and surface soils collected from the same sampling spots were compared in Kunming, China. The total PAH concentrations were 9.35-75.01 ng/m(3) and 101.64-693.30 ng/g dry weight (d.w.), respectively, in TSPs and surface soils. Fluoranthene (FLA), pyrene (PYR), chrysene (CHR), and phenanthrene (PHE) were the abundant compounds in TSP samples, and phenanthrene (PHE), fluorene (FLO), fluoranthene (FLA), benzo[b]fluoranthene (BbF), and benzo[g,h,i]perylene (BghiP) were the abundant compounds in surface soil samples. The spatial distribution of PAHs in TSPs is closely related to the surrounding environment, which varied significantly as a result of variations in source emission and changes in meteorology. However, the spatial distribution of PAHs in surface soils is supposed to correlate with a city's urbanization history, and high levels of PAHs were always observed in industry district, or central or old district of city. Based on the diagnostic ratios and principal component analysis (PCA), vehicle emissions (especially diesel-powered vehicles) and coal and wood combustion were the main sources of PAHs in TSPs, and the combustion of wood and coal, and spills of unburnt petroleum were the main sources of PAHs in the surface soils. The benzo[a]pyrene equivalent concentration (BaPeq) for the TSPs and surface soil samples were 0.16-2.57 ng/m(3) and 11.44-116.03 ng/g d.w., respectively. The incremental lifetime cancer risk (ILCR) exposed to particulate PAHs ranged from 10(-4) to 10(-3) indicating high potential of carcinogenic risk, and the ILCR exposed to soil PAHs was from 10(-7) to 10(-6) indicating virtual safety. These presented results showed that particle-bound PAHs had higher potential carcinogenic ability for human than soil PAHs. And, the values of cancer risk for children were always higher than for adults, which demonstrated that children were sensitive to carcinogenic effects of PAHs.

Characterization and risk assessment of polychlorinated biphenyls in city park soils of Xi'an, China

Polychlorinated biphenyl (PCB) concentrations in surface soil samples (0-10 cm) from 23 city parks (8 urban and 15 suburban) from Xi'an, China were presented. The average concentration of Σ7 PCBs among all the sites was 1.68 ng g(-1) dry weight. High detection frequency (100 %) of PCB 28 and PCB 52 suggested wide occurrence of PCB contaminations in Xi'an. Among these PCBs, PCB 28, 52 and 153 were the most dominant compounds (14.9 %, 39.3 % and 9.5 % of the Σ7 PCBs on average, respectively). "Urban fractionation effect" was found in Xi'An. In other words, PCB concentrations were higher in the urban city park soils than those in suburban park soils. The PCB contamination in Xi'an city park soils were at a low level based on the Dutch guideline. However, dioxin-like PCB congeners were detected from 12 parks, which indicated further investigation was urgently required in future. Furthermore, total PCB concentrations were used to evaluate the cancer risk via ingestion, dermal and inhalation and the results showed that the total cancer risk was at the very low level in this area.

Polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and dibenzofurans, and polycyclic aromatic hydrocarbons around a thermal desorption plant in China

This study was launched to establish comprehensive environmental monitoring on the levels and patterns of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and polycyclic aromatic hydrocarbons (PAHs) both in soil and ambient air around a thermal desorption plant in China. All 209 congeners of PCBs, 136 congeners of PCDD/Fs (P = 4 to 8) and 16 EPA priority PAHs were analyzed. The concentration of PCBs ranged from 20.0 to 536 ng g(-1) (or 0.077-5.27 pg WHO-TEQ g(-1)) in soil and from 972 to 991 ng Nm(-3) (or 0.245-0.374 pg WHO-TEQ Nm(-3)) in air samples, much higher than the levels in cities. A single soil sampling point could have been affected by some transfer of PCBs from the untreated soil by the fingerprint characteristics and the statistical analysis. Establishing blank values prior to the start-up of new plant is a safe and sure method to establish subsequent impacts on the environment. During the treatment of hazardous waste, strict control of all waste materials and all emissions is required.

Assessing risks to adults and preschool children posed by PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) during a biomass burning episode in Northern Thailand

To investigate the potential cancer risk resulting from biomass burning, polycyclic aromatic hydrocarbons (PAHs) bound to fine particles (PM2.5) were assessed in nine administrative northern provinces (NNP) of Thailand, before (N-I) and after (N-II) a haze episode. The average values of Σ 3,4-ring PAHs and B[a] P Equivalent concentrations in world urban cities were significantly (p<0.05) much higher than those in samples collected from northern provinces during both sampling periods. Application of diagnostic binary ratios of PAHs underlined the predominant contribution of vehicular exhaust to PM2.5-bound PAH levels in NNP areas, even in the middle of the agricultural waste burning period. The proximity of N-I and N-II values in three-dimensional (3D) principal component analysis (PCA) plots also supports this conclusion. Although the excess cancer risk in NNP areas is much lower than those of other urban area and industrialized cities, there are nevertheless some concerns relating to adverse health impacts on preschool children due to non-dietary exposure to PAHs in home environments.

Combination of Unmix and positive matrix factorization model identifying contributions to carcinogenicity and mutagenicity for polycyclic aromatic hydrocarbons sources in Liaohe delta reed wetland soils, China

Surface soils were collected from Liaohe delta, China, the largest reed wetland in the world dominated by common reed (Phragmites australis). Samples were analyzed for sixteen priority polycyclic aromatic hydrocarbons (PAHs) by GC/MS. The potential source patterns and source contributions to seven carcinogenic PAH congeners were performed by combining of Unmix and positive matrix factorization (PMF) model with the formula of toxic equivalent quantity (TEQ BaP) and mutagenic equivalent quantity (MEQ BaP), respectively. Four source categories, including petrogenic source, biomass burning, diesel emission and coal combustion, were identified by Unmix and PMF models. For both Unmix and PMF model, the mixed sources (gasoline and diesel engine emission) contributed the most to the TEQ BaP and MEQ BaP, while petrogenic source, the largest contributor for PAHs, made lower contribution to TEQ BaP and MEQ BaP. Minor source contribution difference was found between two models, which might be attributed to uncertainties model parameters and species variables. Hence, it is very essential to use combined source apportionment techniques for quantitatively identifying PAHs sources and estimated their carcinogenicity and mutagenicity.

Gridded field observations of polycyclic aromatic hydrocarbons in soils from a typical county in Shanxi Province, China

Polycyclic aromatic hydrocarbons (PAHs) were measured in 128 soil samples collected from Xiangfen County, Shanxi Province, China. Sixteen PAH congeners were identified at high concentrations (89-100 %), with the exceptions of Ace and Acy, and were used for statistical analysis. PAH concentrations ranged from 51.91 to 10,523.58 ng/g with a mean of 722.35 ng/g indicating severe pollution at the sample sites. Four-ring PAHs were predominant followed by 3- and 5-ring PAHs. Coal combustion was found to be the greatest contributor of PAHs to the local environment. An analysis of the spatial distribution of PAHs indicated the presence of relatively high concentrations in the northwest region of the county. A source identification analysis showed that Wulidun in Fencheng Town, Shangbeirong Village in Gucheng Town, and Yandian Village in Xincheng Town were the major sources of PAHs in Xiangfen County. Modeling results indicated that the distance among the sampling sites and these point sources had a large influence on the transfer of PAHs to the soils.

Effects of benzo[a]pyrene on growth, the antioxidant system, and DNA damage in earthworms (Eisenia fetida) in 2 different soil types under laboratory conditions

The aims of the present study were to compare the toxic effects of benzo[a]pyrene (BaP) and to screen for rapid and sensitive biomarkers that can be used to assess the environmental risks of BaP in earthworms in different natural soil types. The authors exposed Eisenia fetida to 2 types of soil (red soil and fluvo-aquic soil) spiked with different concentrations (0 mg kg(-1), 1 mg kg(-1), 10 mg kg(-1), 100 mg kg(-1), and 500 mg kg(-1)) of BaP for 7 d or 14 d. Benzo[a]pyrene-induced weight variation altered the activities of antioxidant enzymes (superoxide dismutase [SOD]; catalase [CAT]; and guaiacol peroxidase [POD]) and changed the content of malondialdehyde (MDA). In addition, using the comet assay, the authors determined the DNA damage in earthworms. The results revealed that the comet assay was suitable for evaluating the genotoxicity of BaP in the soil, even at the lowest examined concentration. The MDA content was the least sensitive indicator of BaP toxicity. A 3-way analysis of variance (ANOVA) was used to determine whether the soil type, exposure concentration, and duration affected the BaP toxicity. The antioxidant enzyme activities and the MDA content were shown to be significantly correlated with the exposure concentration. The percentage of weight variation (p < 0.001), CAT activity (p < 0.05), and SOD activity (p < 0.01) were significantly affected by the soil type, and the POD activity (p < 0.01), CAT activity (p < 0.001), and SOD activity (p < 0.001) were significantly affected by the exposure duration. Therefore, measuring DNA damage in earthworms is a simple and efficient means of assessing BaP genotoxicity in a terrestrial environment, and the effects of the soil type and exposure time on the other parameters that were investigated in E. fetida, which were used as responsive biomarkers, should be considered.

Combination of Unmix and PMF receptor model to apportion the potential sources and contributions of PAHs in wetland soils from Jiaozhou Bay, China

16 PAHs in Jiaozhou Bay wetland soils were analyzed by GC/MS. The potential sources and contributions were apportioned by Unmix and PMF models. The total concentrations of PAHs ranged from 176.1 to 563.3 ng/g with a mean of 345.3 ng/g. 2- and 3- rings PAHs were the dominant species accounting for 34.7-87.3% of the total PAHs. The similarities and differences of sources and contributions estimated by Unmix and PMF models were discussed. Three common sources (petrogenic source, coking oven and coal combustion) identified by two models, contributed 43.2%, 39.2% and 12.6% by Unmix and 33.5%, 29.1% and 16.0% by PMF to the total PAHs, respectively. In addition, diesel emission source (5.0%) by Unmix and a mixed source of diesel emission and natural gas burning (21.4%) by PMF were also extracted. It is essential to apply multiple source apportionment techniques to estimate potential source and contributions in further study.

Spatial distribution of heavy metal contamination in soils near a primitive e-waste recycling site

The total concentrations of 12 heavy metals in surface soils (SS, 0-20 cm), middle soils (MS, 30-50 cm) and deep soils (DS, 60-80 cm) from an acid-leaching area, a deserted paddy field and a deserted area of Guiyu were measured. The results showed that the acid-leaching area was heavily contaminated with heavy metals, especially in SS. The mean concentrations of Ni, Cu, Zn, Cd, Sn, Sb and Pb in SS from the acid-leaching area were 278.4, 684.1, 572.8, 1.36, 3,472, 1,706 and 222.8 mg/kg, respectively. Heavy metal pollution in the deserted paddy field was mainly concentrated in SS and MS. The average values of Sb in SS and MS from the deserted paddy field were 16.3 and 20.2 mg/kg, respectively. However, heavy metal contamination of the deserted area was principally found in the DS. Extremely high concentrations of heavy metals were also observed at some special research sites, further confirming that the level of heavy metal pollution was very serious. The geoaccumulation index (Igeo) values revealed that the acid-leaching area was severely polluted with heavy metals in the order of Sb > Sn > Cu > Cd > Ni > Zn > Pb, while deserted paddy field was contaminated predominately by metals in the order of Sb > Sn > Cu. It was obvious that the concentrations of some uncommon contaminants, such as Sb and Sn, were higher than principal contaminants, such as Ni, Cu, Zn and Pb, suggesting that particular attention should be directed to Sn and Sb contamination in the future research of heavy metals in soils from e-waste-processing areas. Correlation analysis suggested that Li and Be in soils from the acid-leaching area and its surrounding environment might have originated from other industrial activities and from batteries, whereas Ni, Cu, Zn, Cd, Pb, Sn and Sb contamination was most likely caused by uncontrolled electronic waste (e-waste) processing. These results indicate the significant need for optimisation of e-waste-dismantling technologies and remediation of polluted soil environment.