成都经济区绵阳市部分县（区）土壤有机氯农药剖面分布特征

The vertical distribution of organochlorine pesticides in soils in the area of Mianyang City was studied using GC-ECD. The results showed that in the surface soils with 0~20cm depth, the highest concentration of HCH was observed in the farming land of Youxian District, followed by Santai County and Jiangyou City. In the surface soils with 0~5cm depth, the concentration of DDT in Santai County was significantly higher than that in other regions else. In the surface soils with 5~20cm depth, the highest concentration of DDT was observed in the farming land of Youxian District, followed by Santai County and Jiangyou City. The concentration of organochlorine pesticides decreased with depth. The residues of four isomers of the HCH were significantly different from the components in the industrial products. Generally, in the three soil cores, γ-HCH and δ-HCH had the highest and lowest percentage respectively. The mean values of p, p'-DDT/p and p'-DDE were 0.14, 0.03 and 0.59 respectively. It showed that the DDT content detected in Jiangyou City and Youxian District mainly came from the residues of past application except for Santai County where new contamination of DDT had occurred.