Occurrence and distribution of organochlorine pesticides (HCH and DDT) in sediments collected from East China Sea

Sediments used in this study were collected from different depths of eight sites in East China Sea in November 2002. The levels and distribution patterns of the selected organochlorine pesticides (OCPs =p,p'-DDT, o,p'-DDT, p,p'-DDE, p,p'-DDD, alpha-, beta-, gamma- and delta-HCH) in samples were investigated by the technique of sonication extraction followed by the analysis of gas chromatography (GC) coupled with a micro-electron capture detector (mu ECD). The concentrations of Sigma HCH and Sigma DDT in the surface sediments were in the range of <0.05-1.45 ng/g (mean 0.76 ng/g), <0.06-6.04 ng/g (mean 3.05 ng/g) based on dry weight (dw), respectively. In the vertical distributions, the Sigma HCH and Sigma DDT were in the range of <0.05-2.52 ng/g, <0.06-10.94 ng/g dw, respectively. Residues of OCPs varied significantly with different sampling sites. Sigma DDT in the surface sediments was correlated well with total organic carbon (TOC) content (r =0.71), while Sigma HCH showed no obvious correlation. The distribution showed that the sediments from the vicinity estuary or near shore had higher TOC contents, and higher OCPs concentrations. The contamination record indicated an extensive use of OCPs in the catchments from Yangtze River in the past might greatly affect the OCP residues. (C) 2005 Elsevier Ltd. All rights reserved.