Concentrations and accumulation features of organochlorine pesticides in the Baiyangdian Lake freshwater food web of North China.

Organochlorine pesticides (OCPs), such as hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT), are ubiquitous anthropogenic environmental contaminants. They are persistent, broad-spectrum toxicants that accumulate in the food web with potential risks to the ecosystem and human health. HCHs were the predominant contaminants in Baiyangdian Lake, North China. Concentrations of HCHs and DDTs ranged from 58 to 563 ng/g lipid weight (lw) and 21 to 401 ng/g lw, respectively, for aquatic biota samples. The highest levels of HCHs and DDTs were observed in muscles of yellow catfish. The mean concentrations of OCPs were 4.6 ng/L for water, 95 ng/g dry weight (dw) for aquatic plants, and 14 ng/g dw for sediments. Among the isomers and metabolites, alpha-HCH and p,p'-1,1-di(p-chlorophenyl)-2,2-dichloroethylene (p,p'-DDE) were the predominant congeners in biota samples. Correlations between log lipid-normalized concentrations of HCHs and DDTs and trophic levels (TLs) based on analysis of stable isotopes of nitrogen confirmed that persistent organic pollutants were magnified in the Baiyangdian Lake food web. Significant positive relationships were found for alpha-HCH and p,p'-DDT and their trophic magnification factors, which were 1.6 and 1.7, respectively. These results provide evidence of biomagnification of persistent organic pollutants (POPs) in freshwater food webs.