Distribution Characteristics Of Organochlorine Pesticides In Western Songnen Plain, China

Concentrations of hexachlorocyclohexane (BHC) metabolites and dichlorodiphenyltrichloroethane (DDT) derivatives in the soil, runoff from paddy and dry land as well. as mallard eggs in western Songnen Plain were invesdgated. The concentrations of BHC and DDT in soil and runoff were low and beta-BHC accountin gfor 73.5%-99.5% of the total BHC concentrations was the main metabolite of BHC in runoff, and four metabolites descended in the order; beta>alpha>gamma>delta. DDT is still used locally as p, p'-DDT was detected in the study area. Dissoluble fraction was the dominant form of metabolites and derivatives, and the particle size of suspended substance had significant effect on the pesticide residues in runoff. There were organochlorine pesticides (OCPs) accumulated in the mallard eggs in Songnen Plain, and the residue levels of OCPs were at the same order of magnitude as that in topsoil and suspended substance, but one order of magnitude higher than that of runoff and return flow in farmland. For organism, especially benthon, DDT concentrations posed low ecological risk, while BHC had potential ecological risk in suspended substance of return flow in paddy field.