石门雄黄矿周边农田土壤重金属污染及健康风险评估

湖南石门雄黄矿区环境污染及风险是当前国家环保部门和地方政府极为关注的重要环境问题之一。本研究以该矿区周边农田表层土壤为研究对象,调查分析了矿区周边农田土壤重金属污染状况及其空间分布特征,并采用美国EPA土壤健康风险模型评估了其对人体的健康风险。土壤重金属污染评价结果显示:该区土壤受到中度的As污染和Cd污染,As平均含量为80.26 mg/kg,Cd平均含量为0.55 mg/kg;Cu、Zn、Pb含量均未超过国家《土壤环境质量》的二级标准;综合污染指数显示研究区域为中度污染。美国EPA模型评估结果显示:成人和儿童的日暴露量及非致癌健康风险主要途径均为经手–口摄入,Cd对成人和儿童均不存在非致癌风险和总风险,As对儿童非致癌总风险指数为3.36,造成严重的非致癌健康威胁;经呼吸暴露的致癌风险,Cd对儿童和成人均不造成致癌健康影响,As对成人和儿童的平均致癌风险指数为3.13×10~(-4)和5.58×10~(-4),均存在显著的致癌健康风险,且As、Cd对儿童的健康威胁均高于成人。可见,该矿区周边农田土壤中As、Cd污染及其风险应加强控制与治理。

Pollution and Health Risk Assessment of Heavy Metals in Agricultural Soil Around Shimen Realgar Mine

The pollution and risk of Shimen Realgar Mine is one of the most important environmental problems, which are paid much attention by national environmental protection department and local government. The characteristics of heavy metal pollution in agricultural soil around Shimen Arsenic (As) Mine were analyzed. Moreover, the EPA soil health risk models were adopted to assess human health risk. The assessment results of soil heavy metals pollution and comprehensive pollution index showed that the soils were moderately contaminated by As and Cd. The results showed that the average contents of As, Cd were 80.26 mg/kg and 0.55 mg/kg respectively, Cu, zinc and Pb contents were below the soil environmental quality standard of secondary state. The assessment result by USEPA indicated that hand - mouth intake was the dominating risk exposure pathway of non-carcinogenic. Cd would not cause any non-carcinogenic risk for both adults and childrendidn while the total non-carcinogenic index of As for children(3.36) indicated a significant health threat. Cd would not cause carcinogenic risk of inhalation intake for adults and children while As would, and the average carcinogenic risk indexes of As for adults and children were 3.13×10-4 and 5.58×10-4 respectively. Children were more vulnerable than adults facing As and Cd threats.Thus, the risk prevention and management of As, Cd contaminated soil around the mining area should be strengthened.