[Residues and distribution character of organochlorine pesticides in stream sediments in southwestern suburb of Nanjing].

Sediments and water samples were collected from different cross sections of 4 tributaries of Yangtze River in southwestern suburb of Nanjing city in spring 2004, and agricultural soil sample were collected also in those valleys. The residues and distribution of organochlorine pesticides in sediments from different streams were determined and the influence of soil character on organochlorine pesticides residues in sediments were studied. Result showed that accumulation of HCHs and DDTs occured significantly in the sediments and related to soil erosion. Residues of organochlorine pesticides in sediments may be influenced obviously by pH of agricultural soil in the valleys. In the alkaline soil, organic matters could be leached easily and entered the stream water and accumulated into sediments, resulting in accumulation of organochlorine pesticides adsorbed on soil organic matters in sediments. In the transfer process of materials from soil to water and sediment, constitutes of organochlorine pesticides in multiphase environmental medium were changed; usually those components easily leached from soils had higher residue levels in sediments. Meanwhile, sedimentation of soil in streams could reduce OCPs input to the Yangtze River.