Probabilistic ecological risk assessment of 1,2,4-trichlorobenzene at a former industrial contaminated site
ABSTRACT Measured concentrations of 1,2,4-trichlorobenzene (1,2,4-TCB) in soil and groundwater detected in an industrial contaminated site were used to test several probabilistic options for refining site-specific ecological risks assessment, ranging from comparison of single effects and exposure values through comparison of probabilistic distributions for exposure and effects to the use of distribution based quotients (DBQs) obtained through Monte Carlo simulations. The results of the deterministic approach, which suggest that risk exceeds a level of concern for soil organisms, were influenced mainly by the presence of hot spots reaching concentrations able to affect acutely a large proportion of species, while the large majority of the area presents 1,2,4-TCB concentrations below those reported as toxic. Ground-(pore)water concentrations were compared with aquatic ecotoxicity data in orderto obtain an estimation of the potential risk for aquifers and streams in the adjacent area as well as for soil-dwelling organisms exposed via pore water. In this case, the risk is distributed over a large proportion of the site, while the local risk of hot spots was low, showing that risk characterization based exclusively on soil concentrations might be insufficient.
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ABSTRACT: The objective of the present study was to conduct a probabilistic assessment of risk posed by copper found in the coastal marine environment of China from 2005 to 2012. This was achieved by applying a tiered ecological risk assessment (ERA) approach for characterization of risks of concentrations of copper from nationwide marine water monitoring program. The results show that from 2005 to 2012 the overall trend of hazard quotients (HQs) in the coastal marine environment of China the proportion of locations that exceed a HQ of 1.0 decreased from 64% in 2005 to 31% in 2012. While this indicates an overall improvement of the environment, there still have potential ecological risks in the most of the area, especially for the major gulfs of Liaodong and Bohai Bays and Yellow River Estuary. In addition, probabilities of exceeding the toxicity threshold for 5% of species were 27.6%, 5.4%, 4.9%, 0.8%, 0.4%, 1.0%, 1.8% and 0.12% annually between 2005 and 2012, respectively. Copyright © 2015 Elsevier Ltd. All rights reserved.Marine Pollution Bulletin 02/2015; DOI:10.1016/j.marpolbul.2015.03.005 · 2.79 Impact Factor
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ABSTRACT: 1,2,4-trichlorobenzene (1,2,4-TCB) is one of the most common pollutants in landfill leachate that impacts shallow drinking groundwater quality; accordingly, the transport mechanism and capacity for remediation of this compound are important to the management of local water resource. In this study, a series of indoor experiments and analytical predictions revealed that the transportation of 1,2,4-TCB in groundwater is similar in medium sand and fine sand. Specifically, the peak time increases with distance between monitoring points and the source point, but the peak relative concentrations decrease with distance, indicating that the concentration of 1,2,4-TCB in groundwater is controlled by adsorption and biodegradation. In addition, transportation of water in a fine sand column was lower than that in a medium sand column; therefore, the adsorption and biodegradation of 1,2,4-TCB in groundwater was lower in the medium sand column. These findings demonstrate that 1,2,4-TCB in groundwater could be removed by natural degradation after about 5 years, but that other methods (permeable reactive barriers, air sparging or biosparging) should be applied in the field to shorten the remediation period and enhance water supply safety around landfill.Environmental earth sciences 08/2014; 72(3):941-948. DOI:10.1007/s12665-014-3386-3 · 1.57 Impact Factor
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ABSTRACT: The distribution of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in the surface seawater and sediment of Jincheng Bay mariculture area were investigated in the present study. The concentration of total HCHs and DDTs ranged from 2.98 to 14.87 ng L−1 and were −1, respectively, in surface seawater, and ranged from 5.52 to 9.43 and from 4.11 to 6.72 ng g−1, respectively, in surface sediment. It was deduced from the composition profile of HCH isomers and DDT congeners that HCH residues derived from a mixture of technical-grade HCH and lindane whereas the DDT residues derived from technical-grade DDT and dicofol. Moreover, both HCH and DDT residues may mainly originate from historical inputs. The hazard quotient of α-HCH, β-HCH, γ-HCH and δ-HCH to marine species was 0.030, 0.157, 3.008 and 0.008, respectively. It was estimated that the overall probability of adverse biological effect from HCHs was less than 5%, indicating that its risk to seawater column species was low. The threshold effect concentration exceeding frequency of γ-HCH, p,p′-DDD, p,p′-DDE and p,p′-DDT in sediment ranged from 8.3% to 100%, and the relative concentration of the HCH and DDT mixture exceeded their probable effect level in sediment. These findings indicated that the risk to marine benthos was high and potentially detrimental to the safety of aquatic products, e.g., sea cucumber and benthic shellfish.Journal of Ocean University of China 04/2015; 14(2). DOI:10.1007/s11802-015-2303-z · 0.38 Impact Factor