Vertical distribution of pollutants in soils of a former organochlorine pesticide manufacturing field.

Soil cores were collected and analyzed from the different functional regions of a former organochlorine pesticide manufacturing field to understand the vertical distribution characteristics of HCHs and DDTs in soils.The detection results showed that concentrations of HCHs and DDTs peaked at susface or subsurface horizons and decreased with an increasing depth.There were some slight fluctuations in the decreasing curves in some layers.The results indicated that the levels of organochlorine pesticides in the deep soil layers of the studied site were lower than the detection limit,so the pollutants had an unlikely risk to contaminate the underground water.The analysis of the composition of the pollutants demonstrated that the concentration of DDT in soils was lower than its metabolites,DDD and DDE.β-HCH predominated the HCHs isomers.The pesticide residues during the production period were the major contributor of pollutant accumulation in the soils.The analysis showed that there was a significant correlation between soil organic matter content and the concentrations of organochlorine pesticides in soils of the southwest experimental plant area,which suggested that organic carbon was an important factor for the distribution of OCPs in the soils of the studied field.