Organochlorine pesticides and polybrominated diphenyl ethers in irrigated soils of Beijing, China: Levels, inventory and fate

摘要

Limited information on the levels, inventory and fate of Organochlorine pesticides (OCPs) and Polybrominated diphenyl ethers (PBDEs) in the soils irrigated by sewage or wastewater is available. In this study, variation in concentrations, profiles and fate of OCPs and PBDEs were investigated using soil samples collected from a region irrigated by sewage, mixed water and clean water in the east of Beijing, China. No significant variation was observed among groups, except for penta-BDEs. The measured ∑OCPs and ∑PBDEs residues ranged from 6.4 to 171.2 ng g~(-1) (dw) and 501.9 to 3310.7 pg g~(-1) (dw), respectively. ∑DDTs and BDE-209 were the most abundant congeners accounting for about 76% of ∑OCPs and 93% of ∑PBDEs. Concentrations of hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethane (DDTs) and its major degradation products, and hexachlorobenzene (HCB) ranged from 1.2 to 11.4 ng g~(-1) (dw), 4.0 to 155.6 ng g~(-1) (dw) and 0.3 to 3.4 ng g~(-1) (dw), respectively. The major DDT degradation products were p,p'-DDT and p,p'-DDE. The major hexachlorocyclohexane (HCH) isomer in irrigated soils is p-HCH, reflecting its higher affinity to solids and resistance to degradation than other isomers. Both α-HCH/ β-HCH and p,p'-DDT/p,p'-DDE ratios were log-normally distributed and negatively correlated to log(∑HCHs) and log(∑DDTs), respectively, suggesting no significant recent application of OCPs. Individual BDE congeners, ∑PBDEs and ∑OCPs were significantly correlated with total organic carbon (TOC). Moreover, a good correlationship between ∑PBDEs and black carbon (BC) was obtained but not between ∑OCPs and BC. Sewage irrigation did not have obvious effect on their contaminant levels and inventory of OCPs and PBDEs.