Occurrence and distribution of organochlorine pesticides (OCPs) in surface sediments of the Bohai Sea, China

Fifty-five surface sediment samples covering virtually the entire Bohai Sea (Bohai) were analyzed for organochlorine pesticides (OCPs), in order to provide the extensive information of recent occurrence levels, distribution, possible sources and potential biological risk of these compounds in this area. Concentrations of total dichlorodiphenyltrichloroethanes (DDTs) and hexachlorocyclohexanes (HCHs) in Bohai ranged widely from 0.24 to 5.67 ng g−1 (mean 1.36 ± 0.93 ng g−1) and 0.16 to 3.17 ng g−1 (mean 0.83 ± 0.57 ng g−1), respectively. High concentrations of DDTs were observed in the coastal areas especially at the isolated sites neighboring the harbor or port regions. The recent DDT inputs could be mainly attributed to the agricultural activity (e.g. dicofol), wastewater of chemical plants and the usage of antifouling paint. The distribution pattern of HCHs was different from that of DDTs due to their different physical–chemical properties and amounts of production and usage in the past. (DDE + DDD)/DDT ratios indicated that the degradation of the parent DDT occurred significantly. The contributions of previous and current inputs of pesticides in the coastal areas were distinguished by means of principal component analysis, suggesting that the recent usage of DDT and technical chlordane could serve as important fresh input sources for OCPs. DDTs and chlordanes are the two-main species of OCPs with more ecotoxicological concern in Bohai.