Distribution, Sources And Risk Research Of Polychlorinated Biphenyl (PCBs) In Surface Sediments Of Bohai Sea

As one of the most important inland sea of China, Bohai Sea has many advantages as fishery, salt industry, oil production, port industry and tourism. With the rapid industrialization and urbanization in recent years, huge quantities of pollutants were released into the environment by human activities. The pollutants will accumulate in the sediment, and will cause some adverse effects on the environment and human health. Therefore, a comprehensive understanding of the distribution, sources and risk assessment of PCBs is of great importance in controlling the discharge of pollutants, protecting the environment and human health.This study focused on the PCBs in surface sediments of Bohai Sea. The concentration and distribution of PCBs were reported. In order to quantitatively identify the sources of PCBs, principal component analysis-multiple linear regressions (PCA-MLR) and Partial least squares regression (PLSR) were used. In order to assess the potential risk of PCBs, environmental quality standards and TEQ was used to conduct the ecological risk assessment, and health risk assessment models were used to evaluate the carcinogenic risk and non-carcinogenic risk via food ingestion. In order to minimize the uncertainties of risk assessment, a probability-based approach (Monte Carlo simulation) was successfully applied in this study. A sensitivity analysis was performed to determine the greatest effect of input variables on the risk assessment. We can improve the accuracy of the health risk assessment based on the results of sensitivity analysis. The main contents are as follows:(1) The total concentrations of PCBs (of 38 congeners,∑38PCBs) in Bohai Sea sediments were in the range of 156.5-1699.4 pg/g dw, with a mean value of 469.5 pg/g dw. Tetrachlorobiphenyl contributed 40.7% of the total concentration of PCBs, which is the highest one, followed by trichlorobiphenyl and pentachlorobiphenyl. The proportion of seven indicator PCBs was between 12.1% and 59.0%, and the concentrations of PCB52,49 and 17/18 were the highest. In all sampling sites, trichlorobiphenyl, tetrachlorobiphenyl and pentachlorobiphenyl contributed 52.3%-95.7% to the total concentration.(2) Source apportionment based on PCA-MLR indicated that the main sources of PCBs were unintentional emissions (34.2%), local sources (17.2%). atmospheric deposition (19.5%) and surface runoff (29.0%). While source apportionment based on PLSR indicated that the PCBs were mainly from unintentional emissions (73.8%) and surface runoff (26.2%).(3) The ecological risk assessment revealed that there is no potential ecological risk of PCBs in the sediment of Bohai Sea, and will not cause any adverse effects. Among four kinds of dl-PCBs, PCB 169 contributed most to the TEQ.(4) The health risk assessment indicated that there were no potential carcinogenic and non-carcinogenic risks for children, teens and adults. PCB49 and PCB52 contribute most to the total non-carcinogenic risk, and there was no significant difference between the carcinogenic risks caused by 4 dl-PCBs. Sensitivity analysis revealed that PCBs concentration (C) and exposure duration (ED) were the most sensitive parameters.