Distribution and sources of organochlorine pesticides in sediments from typical catchment of the Yangtze River, China.

Residues of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) and their environmental risks in surface sediments collected from the rivers and lakes in Yangtze River Catchment of Wuhan, China, are investigated in this paper. Based on dry weight (dw), the concentrations of Sigma HCH (alpha-, beta-, and gamma-HCH) and Sigma DDT (p p'-DDT, o p'-DDT, p p'-DDE, p p'-DDD) in sediments ranged from 0.10 to 21.10 ng g(-1) (mean, 4.03 ng g(-1) dw) and 0.79 to 35.61 ng g(-1) dw (average, 6.93 ng g(-1) dw), respectively. Compared with some published guideline values of organochlorine pesticides (OCPs) in sediments, the concentrations of HCHs were at safe levels while the DDT residues would pose adverse biological effects in this studied catchment. The distribution of OCPs in sediments indicated that the input of tributaries was an important factor for OCP residues in the mainstream of the Yangtze River. Levels of OCPs in the sediments were influenced by total organic carbon contents, clay contents, water contents, and pH values of sediments. The present study suggested that historical usage of technical HCH and DDT was the main reason for OCP residues in the sediments from both rivers and lakes. Furthermore, the composition of OCPs reflected additional sources of the holding usage of lindane and fresh inputs of dicofol mixture in this region.