Temporal trend of organic chlorinated pesticides residues in soils of orchard, Beijing

With barren and vegetable soils as control, in 1993 and 2003, the concentrations of Organic Chlorinated Pesticides (OCPs) were measured in topsoils of a selected orchard in Beijing, which was divided into old and new orchard groups, according to the different cultivation history. The results indicated that OCPs (HCHs and DDTs) degraded greatly in the 20 years after the prohibition of their usage. And the levels of total DDTs and HCHs in the old orchard were significantly higher (P0.05) than those in the new. Moreover, the residual levels of HCHs and DDTs in the orchard were higher than those in barren and vegetable soils (P0.05). The pollution potential was assessed on the basis of environmental limits of the greenfood production area in China. New orchard was suitable for the production of greenfood, while old orchard was not suitable, due to relatively higher DDT and HCH pollution.