北京通州某改造区土壤中DDTs和HCHs的地球化学特征及风险评价

选取北京通州环球影城附近某改造区为研究区域，共采集15件表层土壤样品，主要分析了该地区土壤中DDTs和HCHs的空间分布地球化学特征；采集垂向样品，并分析了DDTs和HCHs在土壤垂向剖面中的分布情况。表层土壤样品中大部分的DDTs和HCHs有检出，ΣDDTs的残留量为494~19615 μg·kg-1，ΣHCHs为082~1021 μg·kg-1。土壤垂向剖面分析结果表明，DDTs部分有检出，两剖面中残留量整体随深度变化不明显，但局部出现突变现象；HCHs全部检出，两剖面中残留量整体随着深度增加不断减少。参照国家相关标准对该区土壤环境整体进行评价，初步分析通州区环球影城地区土壤中残留DDTs除个别点符合二级标准外，其余都处于一级标准，残留风险较低；土壤中残留HCHs基本符合一级标准。结合不同异构体之间含量特征及分布，认为该地区局部近期可能存在HCHs输入现象。最后，对该改造区进行了健康风险评价，结果表明该区DDTs和HCHs在致癌风险和部分非致癌风险方面影响较小。

Geochemistry and Risk Assessment of DDTs and HCHs in Soil from a Renewal Area in the Tongzhou District of Beijing

A case study has been completed on the Tongzhou Universal Studios site. 15 surface soil samples in total have been collected for chemical analysis of DDTs and HCHs to reveal any spatial distribution pattern. In addition, some soil samples in two vertical profiles have been analyzed for the DDTs and HCHs concentrations and their distribution patterns. The DDTs and HCHs are detected in most of the surface soil samples, with contents of the ΣDDTs ranging from 494 μg·kg-1 to 19615 μg·kg-1, and contents of the ΣHCHs from 082 μg·kg-1 to 1021 μg·kg-1. In samples from the vertical profiles, the DDTs can only be partially detected and their concentrations are not obviously correlated to the variation of depth, while sudden change in confined depth exists; HCHs are detected in all the samples, and their overall concentration is negatively correlated to depth. Based on the national standard, an overall evaluation of soil environment in this region was conducted. The result shows that only a few samples in this area have DDTs concentration within the second order standard, and the rest within the first order standard, showing a low residual risk. The residual HCHs in soil are basically in accordance with the first order standard. According to the concentration and distribution of the different isomers, we conclude a recent HCHs input in the region. Finally, the health risk assessment in the renewal area, indicates that the HCHs and DDTs have little effect on carcinogenic risk and some non carcinogenic risks.