某铀尾矿库周围农田土壤重金属污染潜在生态风险评价

Potential Ecological Risk Assessment of Heavy Metals Contamination in Farmland Soils near an Uranium Tailings Pond

为能够定量评价铀尾矿库周围农田土壤重金属污染程度及其潜在生态危害性,采用Hakanson潜在生态风险指数法对土壤中重金属进行综合污染评价。结果表明,铀尾矿库周围部分农田土壤中重金属Cd、Ni、As、Cu、Hg、Zn含量存在积累和超标情况,尤以Cd的污染最严重,Ni、As次之;Pb、Cr含量能够满足标准限值要求。潜在生态风险评价结果显示,铀尾矿库周围农田土壤重金属潜在生态风险较高,主要潜在生态风险因子为Cd,其次是Hg、As,Cr、Pb、Ni、Cu、Zn并不构成潜在生态风险。铀尾矿库周围农田土壤中较高水平的Cd在构成环境污染的同时,也构成了较严重的生态危害,应加强对重金属Cd、Hg的生态风险防治。

The potential ecological risk index（ RI）,as the quantitative diagnostic tools,were used to evaluate the contamination situation of various heavy metals（ Cd,Hg,Ni,Zn,Cu,As,Pb and Cr） in paddy soils near an uranium tailings pond. The results showed that some heavy metals such as Cd,Ni,As,Cu,Hg,zinc elements contents were accumulated in farmland soil and the farmland soil was polluted according to common soil assessment standards. It was also discovered that the contamination level of the farmland soil polluted by Cd was most serious especially,followed by Ni and As. Pb and Cr elements contents in the soils could meet the requirements of standard limit. The assessment results by RI showed that the ecological risk of heavy metals in the farmland soil surrounding the tailings was high and the main factor caused the ecological hazard was cadmium,followed by Hg and As. The other heavy metals such as Cr,Pb,Ni,Cu,Zn elements did not constitute a potential ecological risk. The ecological risk of heavy metals such as Cr,Pb,Ni,Cu and zinc elements were in low level. This study suggested that higher levels of Cd element in the soil not only constituted environmental pollution,but also constituted a serious ecological hazard. The ecological risk prevention and control of Cd and Hg elements should be strengthen.