Topsoil dichlorodiphenyltrichloroethane and polychlorinated biphenyl concentrations and sources along an urban-rural gradient in the Yellow River Delta

摘要

The Yellow River Delta(YRD) is a typical agricultural and petrochemical industrial area of China.To assess the current status of soil dichlorodiphenyltrichloroethane(DDT) and polychlorinated biphenyls(PCB) residues,topsoil samples(0-15 cm)(n = 82) were collected in Bincheng District,at the geographic center of the YRD.The total concentrations of six DDT homologues were within 3.3-3819 μg/kg,with a mean concentration of 191 μg/kg,showing significant increase along urban-rural gradient.Soil concentrations of seven indicator PCBs in the area ranged from non-detectable to 87.0 μg/kg,dominated by heavily chlorinated PCBs(PCB-101 and-118).Soil PCBs concentrations were significantly greater in urban than suburban and rural areas.Principal component and multiple linear regression analysis suggest that 86.4% of soil DDTs originate from past DDT usage,and 13.6% originate from dicofol application.Soil PCBs most likely originate from the petrochemical industry(77.1%),municipal solid waste disposal(16.5%),local commercial PCB homologues usage(5.2%),and long-range atmospheric deposition(1.2%).In general,soil DDTs pollution was classified as low level,and mean PCBs concentrations were below the severe contamination classification range.Because PCB-118 is a dioxin-like congener,monitoring and remediation is advised to assess and reduce negative environmental and human health effects from soil DDTs and dioxin-like congeners in the study area.