Occurrence and distribution of organochlorine pesticides (DDT and HCH) in sediments from the middle and lower reaches of the Yellow River, China.

Sediments used in this study were selected from 23 stations in the middle and lower reaches of the Yellow River and its tributaries in November 2005. The levels and distribution patterns of 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 analysis of gas chromatography coupled with micro-electronic capture detector. Concentration of OCPs in the sediments from the Yellow River ranged from 0.05 to 5.03 ng g(-1) (mean, 1.02 ng g(-1)) for summation operatorDDT, 0.09-12.89 ng g(-1) (mean, 1.08 ng g(-1)) for summation operatorHCH. The concentration distribution of summation operatorDDT and summation operatorHCH varied significantly with different sampling station, indicating their different contamination sources. Composition analyses demonstrated that residues of DDTs in sediments came from the previous inputs of organochlorine pesticides, while beta-HCH and gamma-HCH significantly dominated in the sediments for HCHs.