典型流域农田土壤重金属污染特征及生态风险评价

采用野外采样和室内分析相结合的方法，以原有工业污染较严重的某流域农田表层土壤为研究对象，分析了土壤中重金属Hg，Cr，Cd，As，Pb，Cu，Zn和Mn的含量及污染特征，并采用地累积指数法和潜在生态危害指数法对农田土壤重金属污染进行了生态风险评价. 结果表明:研究区农田土壤中各元素的含量均高于背景值，仍存在一定程度的污染，其污染程度由强至弱依次为Cd＞As＞Zn＞Cu＞Pb＞Cr＞Hg＞Mn；研究区农田土壤存在较高的潜在生态风险，在8种重金属中镉的风险指数最高. 表明流域内历史工业污染对农田土壤环境仍具有一定的生态危害性. 

Pollution Characteristics and Ecological Risk Assessment of Heavy Metals in Farmland Soils of a Typical Basin

By means of field investigation and laboratory analysis, the concentrations and pollution characteristics of Hg, Cr, Cd, As, Pb, Cu, Zn and Mn in farmland surface soil from a valley which suffered serious industrial historical pollution were analyzed. The ecological risk assessment of heavy metal pollution in the farmland soil wais discussed with the methods of geoaccumulation index and potential ecological risk index. The results showed that the farmland soils in the research area were polluted by heavy metals, and their concentrations were all above the background values. The enrichment degree of heavy metals ranked as follows: Cd＞As＞Zn＞Cu＞Pb＞Cr＞Hg＞Mn. The potential ecological risk level in the farmland soils in the research area was relatively high. The potential ecological risk of Cd was highest among the eight studied heavy metals, which showed that industrial historical pollutants in the valley were harmful to the ecological environment of farmland soils in the research area.