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    重庆秀山西北部农田土壤重金属生态健康风险评价

    Ecological and health risk assessment of heavy metals in farmland soil of northwest Xiushan, Chongqing

    • 摘要: 为了解矿业活动较多的重庆秀山县西北部农田土壤重金属污染状况,采集了表层土壤样品386件,分析测定As、Cd、Cr、Cu、Hg、Ni、Pb、Zn、Mn等9种重金属元素,采用地累积指数法、潜在生态危害指数法和健康风险评估模型,对该区土壤重金属污染程度、生态风险和健康风险进行评估。结果表明,该区农田土壤9种重金属平均值都高于重庆市土壤背景值,呈现不同程度的积累;Cd、Hg明显超出国家农用地土壤污染风险筛选值,超标率分别为75.2%和44.6%。土壤中Hg污染较严重,处于中污染或重污染状态,Mn、As、Cd总体呈轻污染,其余重金属基本无污染。生态风险评价显示,Hg、Cd为主要生态危害元素,Hg以强、很强和极强风险为主,Cd以中等风险为主。人体健康风险评价显示,儿童更易受到重金属污染威胁,重金属对成人不具有非致癌风险,对儿童具有非致癌风险,As、Cr是主要非致癌因子;成人致癌风险在可接受范围内,个别土壤样对儿童具有致癌风险,As致癌风险最大。

       

      Abstract: In order to understand the heavy metal pollution of farmland soil in northwest Xiushan, Chongqing, with quite a lot of mining activities, the authors collected 386 surface soil samples, analyzed and determined the concentrations of As, Cd, Cr, Cu, Hg, Ni, Pb, Zn and Mn and evaluated the soil heavy metal pollution level, the ecological risk and health risk by using the geological accumulation index, potential ecological hazard index and health risk assessment model. The results show that the average values of 9 heavy metals in the surrounding soil of Xiushan mining area are higher than the soil background values of Chongqing, showing different degrees of accumulation effect. The concentrations of Cd and Hg significantly exceed the risk screening values for soil contamination of agricultural land, with the over-standard rates of 75.2% and 44.6% respectively. In the soil, Hg pollution is relatively serious, and its pollution level is medium pollution or heavy pollution, Mn, As and Cd are generally light pollution, and the remaining heavy metals are basically pollution-free. The potential ecological hazard index shows that Hg and Cd are the main ecological hazard elements, Hg ecological risk is mainly strong to extremely strong, and Cd ecological risk is mainly medium. The heavy metal health risk assessment results show that children are more susceptible to the heavy metal pollution. There are no significant non-carcinogenic risks for adults, children however show significant non-carcinogenic effect, and As and Cr are major non-carcinogenic factors. The carcinogenic risks for adults are acceptable, individual soil samples have carcinogenic effect on children, and As has a relatively higher carcinogenesis risk.

       

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