The distribution of organochlorine pesticides (OCPs) in surface sediments of Bohai Sea Bay, China.

The residues of organochlorine pesticides (OCPs) in 19 surface sediments of Bohai Sea Bay were determined in this study. Total OCP concentration in surface sediment ranged from 9.01 to 18.04 ng/g dry weight, with a mean concentration of 12.50 ng/g. These findings are in the mid-range of pesticide concentrations compared to those reported in other regions worldwide. DDTs and HCHs were the predominant species. The α-HCH/β-HCH ratios and the predominant γ-HCH indicate that the technical HCH contamination was due mainly to historical usage, although there appeared to be a fresh input of lindane. The results from (DDD + DDE)/ΣDDTs and DDD/DDE calculations suggest that the usage of DDT in agricultural activities was not terminated, and the historical/fresh inputs of DDT in these areas could be more easily degraded into DDD under an anoxic condition. PCA implies that the recent usage of DDT could serve as important fresh input sources for OCPs.