Levels and chiral signatures of organochlorine pesticides in urban soils of Yinchuan, China.

In this study, residual level and enantiomeric composition of typical organochlorine pesticides (OCPs) were surveyed in urban soils of Yinchuan, China. The median levels of summation Sigma HCHs and summation Sigma DDTs were 0.852 and 2.24 ng/g, respectively, which suggested little risk for ecological environment and human health in the study area. Both chiral alpha-HCH and o,p'-DDT displayed the non-racemic signatures in all samples. The isomer ratios of summation Sigma HCHs and summation Sigma DDTs combined with enantiomer fractions (EFs) of alpha-HCH and o,p'-DDT, suggested that contamination source of HCHs derived from historical HCHs (including technical HCHs and Lindane) and that of DDTs originated from old source with the usage of mixed technical DDTs and dicofol.