Organochlorine pesticides in the surface water and sediments from the Peacock River Drainage Basin in Xinjiang, China: a study of an arid zone in Central Asia

Fourteen surface water and nine surface sediment samples were collected from the Peacock River and analyzed for organochlorine pesticides (OCPs) by gas chromatograph-electron capture detector (GC-ECD). All the analyzed organochlorine pesticides, except o,p (')-DDT, were detected in sediments from the Peacock River; but in the water samples, only beta-HCH, HCB, p,p (')-DDD, and p,p (')-DDT were detected at some sites. The ranges for total OCPs in the water and sediments were from N.D. to 195 ng l (-aEuro parts per thousand 1) and from 1.36 to 24.60 ng g (-aEuro parts per thousand 1), respectively. The only existing HCH isomer in the water, beta-HCH, suggested that the contamination by HCHs could be attributed to erosion of the weathered agricultural soils containing HCHs compounds. Composition analyses showed that no technical HCH, technical DDT, technical chlordanes, endosulfans, and HCB had been recently used in this region. However, there was new input of gamma-HCH (lindane) into the Peacock River. The most probable source was water flowing from Bosten Lake and/or agricultural tailing water that was returned directly into the Peacock River. DDT compounds in the sediments may be derived mainly from DDT-treated aged and weathered agricultural soils, the degradation condition was aerobic and the main product was DDE. HCB in the sediment might be due to the input from Bosten Lake and the lake may act as an atmospheric deposition zone. There was no significant correlation between the concentrations of OCPs (including aHCH, aDDT, chlordanes, endosulfans, HCB and total OCPs) and the content of fine particles (< 63 mu m). The concentrations of OCPs were affected by salinity.