Distribution of HCHs and DDTs in soils from Beijing City, China

Concentrations of HCH isomers, DDT, and its metabolites have been measured in 63 soil samples collected in the urban area and outskirts of Beijing City. HCHs and DDTs were observed in all samples and their geometric mean levels were 5.78 and 38.21 ng g(-1), respectively. The spatial distribution of OCPs in Beijing was clearly showed by the contour map, suggesting the sites with the higher level of OCPs are located in the west and the south region and urban areas within the study regions." Furthermore, a t-test showed a significant difference of the level of some compounds between urban and outskirts areas. The temporal distribution of HCHs and DDTs suggested that the historical application of OCPs has a great effect on the residual level. The ratios of (alpha-/gamma -HCH (p,p'-DDE+p,p'-DDD)/p,p'-DDT, and o,p'-DDT/p,p'-DDT indicated the present of lindane and impure dicofol besides technical HCHs and technical DDTs in Beijing. The potential risk of HCHs and DDTs was assessed on the basis of some current guideline values for soil. The level of OCPs in our study area was compared with other studies.