Occurrence and assessment of organochlorine pesticides in the agricultural topsoil of Three Gorges Dam region, China

Sixteen organochlorine pesticides (OCPs) were investigated in the 80 agricultural topsoil samples of Three Gorges Dam region, China. The concentration of OCPs ranged from 1.26 to 22.15 ng g−1, with a mean concentration 6.49 ng g−1. Dichlorodiphenyltrichloroethanes (DDTs) and hexachlorocyclohexanes (HCHs) were predominant compared to other OCPs, with mean concentrations 1.80 and 1.27 ng g−1, respectively, accounting for 28 and 20 % of the total OCPs. Ratio analysis indicated that there is new input of DDTs in this study area. However, HCHs residual was mainly from historical use and atmospheric deposition. Other OCPs were due to the historical use in the studied area. Based on the soil quality guideline, both DDTs and HCHs pollution were in the low pollution level. Cancer risk assessment indicated that OCPs concentrations in this area presented a low cancer risk level. The study can offer some reference to the land management in the Three Gorges Dam region.