Source and Vertical Distribution of Organochlorine Pesticide Residues in Soils from a Typical Chemical Industrial Area

Concentrations of organochlorine pesticides(OCPs) were investigated in surface and deep soils from a typical chemical industrial area in Beijing.Results indicated that average concentrations of HCHs and DDXs were 5,470 ng/g and 2,110 ng/g respectively,much higher than the concentrations in agricultural and urban soils,which indicated that industrial area had been polluted by OCPs,with high OCPs concentration located at the production workshop and storage of the former pesticide plant.Principal component analysis and Kendall correlation analysis were used to explore the source and influencing factors of OCPs,results showed that DDT pollution is a mix of technical DDT and Dicofol while HCHs pollution input is only due to technical HCH sources.pH and TOC have no obvious effect on OCPs distribution.OCPs concentration in deep soils from the former pesticide plant were very high,OCPs concentrations in deep soils from other factories also were much higher than those in agricultural deep soils,which indicated the deep soils in industrial area were polluted by OCPs.Concentrations of HCHs and DDTs in most sampling sites tended to decrease gradually from topsoil to bottom layer while there were some slight fluctuations in decreasing process in some sampling sites.Due to disturbance of soils from the industrial area,the regularity of OCPs vertical distribution was not obvious.