Occurrence of organochlorine pesticides from typical water sources in YiXing City, Taihu Upper-River Basin, East China

This study is the first report to describe the occurrence of 18 organochlorine pesticides (OCPs) in the three typical water sources in YiXing City, Taihu Upper-River Basin, East China. The fates of the target OCPs in the Jiubin drinking water treatment plant (JTP) were also analysed. The amount of OCPs in the Hengshan (HS), Youche (YC) and Xijiu (XJ) water sources were relatively moderate, with mean concentrations of 535.6, 426.5 and 537.8 ng L¹, respectively. Hexachlorocyclohexanes (HCHs) dominated the total concentration of the OCPs making up a marked portion of the 18 OCPs. The highest levels of OCPs found in the three water sources during the study period were during the dry season. The occurrence and concentrations of these compounds were spatially dependent, and the mean concentrations of OCPs in HS, YC and XJ increased from the surface layer to the bottom layer with various percentage increases. In addition, the removal efficiencies of the OCPs from the sedimentation, filtration and disinfection in the JTP are limited. Beta-hexachlorocyclohexane (β-HCH) and heptachlor posed a cancer risk for children and adults in YiXing City, while the potential ecosystem risk of the other OCPs was relatively low in the three water sources. However, the risks posed by the OCPs due to ingestion of drinking water may still exist; therefore, special attention should be paid to source control into the JTP and advanced treatment processes for drinking water supplies should be implemented.