Spatial variability and temporal trends of HCH and DDT in soils around Beijing Guanting Reservoir, China.

Spatial variability and temporal trends in concentrations of the organochlorine pesticides (OCPs), hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT), in surface soils around Beijing Guanting Reservoir (GTR) were studied in 2003 and 2007. Concentrations of the two OCPs in soils around GTR were generally less than reference values set by the Chinese government for the protection of agricultural production and human health. Among the OCPs, β-HCH and p, p'-DDE were the two predominant compounds. This result indicates that the HCH and DDT residues in soils were primarily from historical use. Based on kriging, a spatial distribution of HCH and DDT around the GTR was observed. Spatial variability indicated how HCH and DDT had been applied and been distributed in the past. Between 2003 and 2007, concentrations of HCH and DDT decreased more rapidly in orchard soils than those in fallow soils.