Risk assessment and sources of polycyclic aromatic hydrocarbons in agricultural soils of Huanghuai plain, China

Studies on polycyclic aromatic hydrocarbons in surface sediments of Mithi River near Mumbai, India: Assessment of sources, toxicity risk and biological impact

This study investigated the levels, sources and potential risks of 17 polycyclic aromatic hydrocarbons in surface sediment samples collected along the Mithi River of Mumbai. The concentration level of ΣPAHs found in the present study was in the range of 1206-4735 ng/g dw. The composition patterns of PAHs by ring size in sediment were surveyed which indicate the dominance of four rings followed by five and three ring PAHs. In the study it was observed that the high molecular weight PAHs (HMW PAHs) made greater contributions of 90.83% as compared to that of low molecular PAHs (LMW PAHs) contributing to 9.17% to the total PAH concentrations. Toxicity and biological risk were assessed using toxic equivalent quantity and sediment quality guideline quotient. It is feared that the pollution level of PAHs in the sediments might increase in coming times resulting in an unconspicuous risks for the environment and humans through food chains.

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.

Carcinogenic potential of PAHs in oil-contaminated soils from the main oil fields across China

The concentrations, composition profiles, and sources of polycyclic aromatic hydrocarbons (PAHs) were analyzed in 55 surface soil samples collected from four oil fields across China (Daqing, DQ; Shengli, SL; Xinjiang, XJ; and Huabei, HB). The total 16 priority PAHs concentrations of DQ, SL, XJ, and HB ranged from 857 to 27,816; 480 to 20,625; 497 to 43,210; and 12,112 to 45,325 ng/g, respectively, with means of 9160; 6394; 13,569; and 22,954 ng/g and the seven possible carcinogenic PAHs accounted for 8-25.7 % of the total PAHs. Almost all the samples were heavily contaminated, and phenanthrene, chrysene, and pyrene were the most dominant components. The PAH isomeric ratios indicated that PAHs in oil fields mainly originated from petroleum. The toxic assessment illustrated that people living and working in oil fields would suffer low carcinogenic risk, which was somehow coincided with the results of epidemiological survey on cancer incidence. It seems essential to pay more attention to the chronic human health effects of exposure to oil fields and to focus new studies on the public health field that involves a large number of people all over the world.

Quantitative analysis and health risk assessment of polycyclic aromatic hydrocarbons in edible vegetable oils marketed in Shandong of China

This work studies on the quantitative analysis and health risk assessment of polycyclic aromatic hydrocarbons (PAHs) in edible vegetable oils in Shandong, China. The concentrations of 15 PAHs in 242 samples were determined by high performance liquid chromatography coupled with fluorescence detection. The results indicated that the mean concentration of 15 PAHs in oil samples was 54.37 μg kg(-1). Low molecular weight PAH compounds were the predominant contamination. Especially, the carcinogenic benzo(a)pyrene (BaP) was detected at a mean concentration of 1.28 μg kg(-1), which was lower than the limit of European Union and China. A preliminary evaluation of human health risk assessment for PAHs was accomplished using BaP toxic equivalency factors and the incremental lifetime cancer risk (ILCR). The ILCR values for children, adolescents, adults, and seniors were all larger than 1 × 10(-6), indicating a high potential carcinogenic risk on the dietary exposed populations.

Potential sources of and ecological risks from heavy metals in agricultural soils, Daye City, China

Concentrations of eight heavy metals (arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), and zinc (Zn)) were measured in 92 topsoil samples collected from agricultural areas in Daye City to (1) assess the distribution of these heavy metals, (2) discriminate natural and anthropic contributions, and (3) identify possible sources of pollution. Mean concentrations of As, Cd, Cu, and Zn in the investigated soils were 23.8, 1.41, 105, and 159 mg kg(-1), respectively. These values were higher, in some cases by several orders of magnitude, than their corresponding background values. Estimated ecological risks, based on contamination factors and potential ecological risk indexes, were mostly low, but were considerable for As and Cd. A range of basic and multivariate statistical analyses (Pearson's correlation analysis, hierarchical cluster analysis, and principal component analysis) clearly revealed two distinct metal groups, comprising As/Cd/Cu/Zn and Cr/Ni/Hg/Pb, whose concentrations were closely associated with the distribution and pollution characteristics of industries in and around the city. Results demonstrated that As/Cd/Cu/Zn were indicators of anthropic pollution, while Cr/Hg/Ni/Pb were from parent materials. Maps of pollutant distribution compiled for the entire arable area further indicated that non-ferrous metal smelting and mining is the main source of diffuse pollution, and also showed the contribution of point source pollution to metal concentrations in agricultural topsoil. Results of this study will be useful for planning, risk assessment, and decision making by environmental managers in this region.

Occurrence, sources, and potential human health risks of polycyclic aromatic hydrocarbons in agricultural soils of the coal production area surrounding Xinzhou, China

A comprehensive investigation of the levels, distribution patterns, and sources of polycyclic aromatic hydrocarbons (PAHs) in agricultural soils of the coal production area surrounding Xinzhou, China, was conducted, and the potential human health risks associated with the levels observed were addressed. A total of 247 samples collected from agricultural soils from the area were analyzed for sixteen PAHs, including highly carcinogenic isomers. The PAH concentrations had a range of n.d. to 782ngg(-1), with a mean value of 202ngg(-1). The two-three ring PAHs were the dominant species, making up 60 percent of total PAHs. Compared with the pollution levels and carcinogenic potential risks reported in other studies, the soil PAH concentrations in the study area were in the low to intermediate range. A positive matrix factorization model indicates that coal/biomass combustion, coal and oil combustion, and coke ovens are the primary PAH sources, accounting for 33 percent, 26 percent, and 24 percent of total PAHs, respectively. The benzo[a]pyrene equivalent (BaPeq) concentrations had a range of n.d. to 476ngg(-1) for PAH7c, with a mean value of 34ngg(-1). The BaPeq concentrations of PAH7c accounted for more than 99 percent of the ∑PAH16, which suggests that seven PAHs were major carcinogenic contributors of ∑PAH16. According to the Canadian Soil Quality Guidelines, only six of the soil samples had concentrations above the safe BaPeq value of 600ngg(-1); the elevated concentrations observed at these sites can be attributed to coal combustion and industrial activities. Exposure to these soils through direct contact probably poses a significant risk to human health as a result of the carcinogenic effects of PAHs.

Potential source apportionment of polycyclic aromatic hydrocarbons in surface sediments from the middle and lower reaches of the Yellow River, China

In this work, principal component analysis/multiple linear regression (PCA/MLR), positive matrix factorization (PMF), and UNMIX model were employed to apportion potential sources of polycyclic aromatic hydrocarbons (PAHs) in surface sediments from middle and lower reaches of the Yellow River, based on the measured PAHs concentrations in sediments collected from 22 sites in November 2005. The results suggested that pyrogenic sources were major sources of PAHs. Further analysis indicated that source contributions of PAHs compared well among PCA/MLR, PMF, and UNMIX. Vehicles contributed 25.1-36.7 %, coal 34.0-41.6 %, and biomass burning and coke oven 29.2-33.2 % of the total PAHs, respectively. Coal combustion and traffic-related pollution contributed approximately 70 % of anthropogenic PAHs to sediments, which demonstrated that energy consumption was a predominant factor of PAH pollution in middle and lower reaches of the Yellow River. In addition, the distributions of contribution for each identified source category were studied, which showed similar distributed patterns for each source category among the sampling sites.

Association of soil polycyclic aromatic hydrocarbon levels and anthropogenic impacts in a rapidly urbanizing region: spatial distribution, soil-air exchange and ecological risk

The occurrence of polycyclic aromatic hydrocarbons (PAHs) in soil of the Pearl River Delta (PRD) and surrounding areas was examined on a basis of six land-use types and four geographic regions, from which the impacts of anthropogenic events on the terrestrial environment were evaluated. No significant difference in the concentrations of Σ28PAH and Σ15PAH (sums of 28 and 15 PAHs, respectively) was found among the land-use types of industry, landfill and residency. On the other hand, higher soil PAH concentrations occurred in the central PRD characterized by dense population and high urbanization level, compared to other geographic regions. Source diagnostics implicated the combustions of coal and refined petroleum as the major input sources of anthropogenic PAHs. Furthermore, low molecular weight PAHs tended to volatilize from soil to air while the opposite was prevailing for high molecular weight PAHs. The mean annual diffusive flux of Σ15PAH (852 μg m(-2)yr(-1)) from the soil to the atmosphere in the central PRD was greater than those in the PRD's periphery (195 μg m(-2)yr(-1)), West region (322 μg m(-2)yr(-1)) and East region (84.9 μg m(-2)yr(-1)), suggesting that the central PRD may have become a secondary source of PAHs to the surrounding areas. Finally, ecological risk assessment based on the classification from Maliszewska-Kordybach showed that 3.5% of soil within the central PRD was heavily contaminated by PAHs and 5.2 million residents may be subjected to high health risk.

Isolation and characterization of a newly isolated pyrene-degrading Acinetobacter strain USTB-X

The pryene-degradation bacterium strain USTB-X was newly isolated from the polycyclic aromatic hydrocarbon (PAH)-contaminated soil in Beijing Coking Plant, China. The strain was identified as Acinetobacter with respect to its 16S rDNA and morphological and physiological characteristics. The strain was Gram-negative, non-mobile, non-acid-fast, and non-spore-forming, short rods in young culture and 0.8-1.6 μm in diameter and 1.2-2.5 μm long in the stationary phase of growth. Strain USTB-X could utilize pyrene, naphthalene, fluorene, phenanthrene, benzene, toluene, ethylbenzene, ethanol, methanol, and Tween 80 as sole source of carbon and energy. The strain could produce biosurfactants which enhanced the removal of pyrene and could remove 63 % of pyrene with an initial concentration of 100 mg·L-1 in 16 days without other substrates. Based on the intermediates analyzed by gas chromatography-mass spectrometry, we also deduced the possible metabolic pathway of strain USTBX for pyrene biodegradation. Results indicated that the strain USTB-X had high potential to enhance the removal of PAHs in contaminated sites.

Assessment of occupational exposure to polycyclic aromatic hydrocarbons via involuntary ingestion of soil from contaminated soils in Lagos, Nigeria

Soils from 12 sites in Lagos area, Nigeria impacted by anthropogenic activities were extracted by ultrasonication and analysed for the concentration of 16 priority polycyclic aromatic hydrocarbons (PAHs) by gas chromatograph-mass spectrometer (GC-MS). The concentration of the sum of PAHs ranged from 0.2 to 254 μg/g at these sites. The sum benzo[a]pyrene-equivalent dose (BaPeq) at the sites ranged from 0.0 (K, forest soil) to 16.7 μg/g (C, the lubricating oil depot soil). Mean daily intake (MDI) for the composite soils samples when compared that of food revealed that some of the individual PAH in samples from sites A (Dump site), C (Depot and loading point for used for black oil), F (Dump site), G(petroleum depot), H (Roadside) and L (Car park) exceeded the recommended the recommended MDI threshold for food, indicating some risk associated with activities on these sites based on this ingestion estimate exceeded value. 8.2 × 10(-6), 7.1 × 10(-7), 1.2 × 10(-4), 4.9 × 10(-7), 7.3 × 10(-7), 1.4 × 10(-5), 7.9 × 10(-5), 4.6 × 10(-6), 3.4 × 10(-7), 2.4 × 10(-7), 2.2 × 10(-7) and 1.1 × 10(-4) estimated theoretical cancer risk (ER) for an adult with a body weight of 70 kg working on sites were composite soil samples A, B, C, D, E, F, G, H, I, J, K and L respectively were sampled. The ER from occupational exposure to surface soil based on oral ingestion were all higher than the target risk of 1 × 10(-6) for normal exposure but were all within the 1 × 10(-4) for extreme exposure for most of the sites except for site C and L. The differences in concentration and risk were related to the different activities (e.g., handling of petroleum products, open burning, bush burning) undertaken at these locations. However, it should be noted here that the resultant risk could be overestimated, since these calculations were based on an exhaustive extraction technique which may be different from uptake by the human guts (bioavailability study).

Ecological risks and potential sources of heavy metals in agricultural soils from Huanghuai Plain, China

A total of 224 agricultural soil samples from Huanghuai Plain in China were investigated for the concentrations of seven heavy metals (As, Cd, Cr, Hg, Ni, Pb, and Zn). The mean concentrations of the metals were 12, 0.17, 79, 0.04, 35, 25, and 74 mg/kg, respectively. These values are similar or slightly higher than background values in this region, except for Cd with a mean nearly twice the background value. The estimated ecological risks based on contamination factors and potential ecological risk indexes are also mostly low, but considerable for Cd and Hg. Multivariate analysis (including Pearson's correlation analysis, hierarchical cluster analysis, and principal component analysis) clearly revealed three distinct metal groups, i.e., Cr/Ni/Zn, As/Cd/Pb, and Hg, whose concentrations were closely associated with the distribution and pollution characteristics of industries in and around the plain. The main anthropogenic sources for the three metal groups were identified as atmospheric deposition, sewage irrigation/fertilizers usage, and atmospheric deposition/irrigation water, respectively. The present results are well suited for planning, risk assessment, and decision making by environmental managers of this region.

Levels, composition profiles and sources of polycyclic aromatic hydrocarbons in surface sediments from Nan'ao Island, a representative mariculture base in South China

Levels, composition profiles and sources of 16 polycyclic aromatic hydrocarbons (PAHs) in surface sediments from Nan'ao Island, one of the largest mariculture bases in South China were investigated. The total PAHs concentrations ranged from 265.49 to 951.27 ng/g (dry weight) with a mean of 515.90 ng/g, and seven possible carcinogenic PAHs accounted for 76.94% of total PAHs. Among various mariculture sections, the highest PAHs level was found in the large seaweed culture; while the lowest concentration was detected in the abandoned culture. The composition of PAHs was characterized by low molecular weight PAHs, and Phe Ant and Pyr were the dominant constituent. PAHs may be mainly originated from petroleum and combustion of biomass and coal. Risk assessments suggested that the probability of adverse effect was lower than 25% and PAHs exposure was moderately carcinogenic.

Source apportionment of polycyclic aromatic hydrocarbons in soils of Huanghuai Plain, China: comparison of three receptor models

Receptor models are useful tools to identify sources of a specific pollutant and to estimate the quantitative contributions of each source based on environmental data. This paper reports on similarities and differences in results achieved when testing three receptor models for estimating the sources of polycyclic aromatic hydrocarbons (PAHs) in soils from Huanghuai Plain, China. The three tested models are Principal Component Analysis with Multiple Linear Regression (PCA-MLR), Positive Matrix Factorization (PMF) and Unmix. Overall source contributions as well as modeled ∑PAHs concentrations compared well among models. All three models apportioned three common PAH sources: wood/biomass burning, fossil fuel combustion and traffic emission, which contributed on average 27.7%, 53.0% and 19.3% by PCA-MLR, 36.9%, 27.2% and 16.3% by PMF, and 47.8%, 21.1% and 18.3% by Unmix to the total sum of PAHs (∑PAHs), respectively. Moreover, the spatial evolution of the common sources were well correlated among models (r=0.83-0.99, p<0.001). In addition, the PMF and Unmix models allowed segregating an additional source from the fossil fuel combustion source, with 19.6% and 11.8% contributions to ∑PAHs, respectively. The current findings further validate that different receptor models provide divergent source profiles, which are mainly attributed to both the model itself and/or the underlying dataset. It is therefore generally recommended to apply multiple techniques to determine the source apportionment in order to minimize individual-method weaknesses and thereby to strengthen the conclusion.