西南某煤矿区土壤重金属污染特征及人群健康风险评价

Contamination characteristics and health risk assessment of soil heavy metals in a coal mine area in Southwest China

目的探讨西南某煤矿区土壤重金属污染特征及人群健康风险。方法于2014年4—8月采集西南某煤矿区土壤,测定其重金属元素Pb、Cd、Hg、As、Cu的含量。采用潜在生态风险指数法、地积累指数法对土壤生态环境质量进行评价,结合美国环保署人体暴露健康风险评价法对土壤重金属健康暴露风险进行评价。结果除Pb、Hg、As外,研究区土壤中Cd、Cu的平均含量均超过贵州省土壤背景值,分别是背景值的1.02、3.33倍。研究区土壤中5种重金属潜在生态风险指数(RI)平均为91.36,整体处于Ⅰ级轻微生态风险,Cd和Hg是造成土壤重金属污染的潜在生态风险因子。地积累指数评价表明,研究区土壤Cu污染最严重,Pb、Hg、As尚不构成土壤污染。健康风险评价结果表明,儿童和成人日暴露剂量均值均为Cu>Pb>As>Cd>Hg,经口摄入是儿童和成人非致癌健康风险和致癌健康风险的主要途径。Cd对儿童的致癌风险指数(CRn)为3.06×10-6,可能存在致癌风险;对成人的CRn为4.94×10-7,不存在致癌风险。As对儿童的CRn为1.24×10-4,存在致癌风险;对成人的CRn为1.79×10-5,可能存在一定的致癌风险。As对区域非致癌健康风险(HI)和致癌健康风险(CRtotal)的贡献率最高。结论本研究区土壤重金属整体处于轻微生态风险,Cu、Cd、Hg是土壤污染治理的重点,应防范As的暴露风险,加强预防重金属经口摄入暴露途径对健康的影响。

Objective To understand the contamination characteristics and health risk of heavy metals in soil of a coal mine area in Southwest China. Methods From April to August 2014,the contents of heavy metals,such as Pb,Cd,Hg,As and Cu,were measured in the soils of a coal mining area in Southwest China. Potential ecological risk index method and geoaccumulation index method were applied to evaluate soil quality,combined with the human exposure health risk assessment method recommended by Environmental Protection Agency(USEPA) to evaluate health risk of heavy metals in soil. Results In addition to Pb,Hg and As,the average contents of Cd and Cu among five heavy metals tested all exceeded the soil background value of Guizhou province,which were 1.02 and 3.33 times as high as those of background values respectively. The average potential ecological risk index RI in the investigated area was 91.36,overall level revealed light ecological risk,Cd and Hg were the potential ecological risk factors inducing heavy metal contamination in soil;The evaluation of land accumulation index indicated that Cu presented the most seriously contamination in soil of the investigated area,Hg and As in soil presented no contamination. The mean exposure dose of children and adults ranked as Cu>Pb>As>Cd>Hg,hand-mouth ingestion was the main route of non-carcinogenic health risk and carcinogenic health risk in children and adults.The carcinogenic risk(CRn) of Cd for children was 3.06×10-6,which might have cancer risk;For adults,the CRnwas 4.94×10-7,which had no cancer risk.The CRnof As was 1.24 ×10-4 for children and 1.79 ×10-5 for adults,which had carcinogenic risk for children and might be carcinogenic for adults respectively. As presented the highest contribution rate of non-carcinogenic health risk and total carcinogenic risk in the investigated area. Conclusion Heavy metals in soil in the investigated area reveals light ecological risk as a whole. Cu,Cd and Hg should be the focus of soil contamination control,and the exposure risk of As should be prevented,and the countermeasures to prevent health impact induced by exposure to heavy metals through hand-mouth route should be strengthened.