Organochlorine pesticides in sediments of Laizhou Bay and its adjacent rivers, North China

Organochlorine pesticides (HCHs, DDTs and HCB) have been investigated in sediments of Laizhou Bay and its adjacent rivers. The average concentrations of HCHs, DDTs and HCBs are 0.09 ng/g dw, 0.59 and 0.05 for marine sediments and 0.55, 8.6 and 1.1 for riverine sediments, respectively. Laizhou Bay is less contaminated by HCHs and DDTs in comparison with other coastal regions around the world, including the other two biggest bays in Bohai Sea. Fresh input of lindane and dicofol-type DDT were found in several riverine sites. Relatively strong TOC-dependence of HCB distribution in the entire studied area suggested no point source existed and/or water sediment equilibrium achieved. No significant difference of alpha/gamma-HCH ratios have been observed between marine and riverine sediments. However, o,p'-DDT/p,p'-DDT ratios varied largely between the two regions. (C) 2011 Elsevier Ltd. All rights reserved.