某化工厂爆炸场地土壤污染物的分布特征及风险评估

以某发生爆炸事故的有机化工厂遗留地块为研究对象，运用单因子指数法、综合污染指数法和HJ 25.3—2019《建设用地土壤污染风险评估技术导则》中推荐的风险评估模型，对场地的污染程度和健康风险进行评价，并基于人体健康风险评估，提出目标污染物的风险控制值。结果表明:土壤中的超标污染物为1，1，2-三氯乙烷、氯苯和1，4-二氯苯，主要富集于研究区中部及西北部下层土壤（2~8 m）中。单因子污染指数结果表明:3种有机物在下层土壤中存在不同程度的污染，其中氯苯的污染程度最为严重。综合污染指数结果表明:表层土壤未污染，部分下层土壤的综合污染程度呈重度污染水平。健康风险评价结果表明:研究区中部及西北部下层土壤的致癌风险和危害商超出可接受阈值，主要暴露风险来自氯苯和1，4-二氯苯等气态污染物的室内吸入途径。风险控制值计算结果表明:污染物的风险控制值远低于最大检出值，选择分层计算的风险控制值作为修复目标值时，可有效减少污染治理量。

DISTRIBUTION CHARACTERISTICS AND RISK ASSESSMENT OF SOIL POLLUTANTS IN AN EXPLOSION SITE OF A CHEMICAL PLANT

With an abandoned land area after an explosion accident in an organic chemical plant as the research subject, the soils at different depths were evaluated using the single-factor pollution index, and comprehensive pollution index, as well as the risk assessment model recommended in the Technical Guidelines for Soil Pollution Risk Assessment of Construction Land, HJ 25.3-2019. Further, we evaluated the pollution degree and health risk of the site, and proposed risk control values of pollutants based on human health risk assessment. The results showed that excessive pollutants in the soil comprised 1,1,2-trichloroethane, chlorobenzene and 1,4-dichlorobenzene, which were mainly concentrated in the central and northwest subsoil (2 to 8 meters deep) of the study area. The results of the single-factor pollution index assessment showed that these three organic compounds displayed different degrees of pollution in the subsoil, with chlorobenzene as the most serious pollutant. The results of the comprehensive pollution index assessment showed that the topsoil was not polluted, whereas the comprehensive pollution degree of some areas in the subsoil was severe. The health risk assessment results showed that the cancer risks and hazard quotient in the central and northwest subsoil of the study area exceeded the acceptable threshold. The primary exposure risk came from the indoor inhalation pathway of gaseous pollutants, such as chlorobenzene and 1,4-dichlorobene. The calculation results of the risk control value showed that the risk control value of pollutants was far lower than the maximum detection value. When the risk control value calculated by layers was selected as the repair target value, the amount of pollution could be effectively reduced.