北京市郊再生水灌区土壤有机氯农药垂向分布特征

在北京市郊再生水灌区采用正三角型布点法进行了3个钻孔的采样工作,钻孔间隔为1m,从表层开始每隔0.5m取一个样,3个钻孔共36组样品,同时采集钻孔附近的灌溉水及地下水,分别测试了土壤的理化参数及其土壤、灌溉水及地下水中9种有机氯农药的质量分数。测试结果表明：表层土壤是有机氯农药的主要残留层,表层土壤中检出的DDTs和BHCs质量分数较高,分别为2814.21ng·kg^-1和1130.41ng·kg^-1,但均符合土壤环境质量一级标准,残留污染程度较轻;其他层位以七氯和艾氏剂为主要检出物,最高质量分数分别为1286.19ng·kg^-1和781.23ng·kg^-1;其中艾氏剂未在表层土壤中检出;灌区内未检出的γ-BHC和（DDE＋DDD）/DDT的计算值为1.80,都说明近期内没有新污染源的输入;检出的有机氯农药在土壤剖面上的迁移能力有HEP〉ALD〉BHCs〉DDTs〉HCB,与地下水中检出的规律一致。

Verticle distribution of organochlorine pesticides in reclaimed water irrigation area in Beijing suburbs

Using triangular distribution method,three profiles were drilled in reclaimed water irrigation area of Beijing suburbs.The interval of each drill hole is 1 m.Soil samples were collected from the surface to 5.5 m with an interval of 0.5 m.There were 36 soil samples in total.At the same time,the irrigation water and groundwater samples were collected.The physical and chemical parame-ters of soil and concentrations of nine organochlorine pesticides in topsoil,irrigation water and groundwater were determined in the lab.The results showed that the topsoil is the major residual layer for organochlorine pesticide.The detected concentrations of DDTs and BHCs were 2 814.21 ng·kg-1 and 1 130.41 ng·kg-1,respectively,which still meet the first standard of environmental quality of soil.,Heptachlor and aldrin were the main contaminants found in other layers,the highest concentrations were 1 286.19 ng·kg-1 and 781.23 ng·kg-1,respectively.Aldrin was not detected in topsoil.γ-BHC was not detected and the value of（DDE＋DDD）/DDT was 1.80.This indicated that there was no contaminant input from the new contamination recently.The migration ability of organochlo-rine pesticides detected in profiles was in an order of HEPALDBHCsDDTsHCB,which is consistent with their detection fre-quency in groundwater.