铅锌矿区土壤重金属污染特征及污染风险评价

为研究铅锌矿区土壤重金属的环境污染特征并评价其风险，以湖南某铅锌矿区土壤为研究对象，利用X射线衍射谱(X-ray diffraction，XRD)分析土壤矿物组成，在微波消解土壤样品后采用电感耦合等离子体质谱法（ICP-MS）检测重金属浓度，利用欧洲共同体修正（BCR）法分析土壤中重金属赋存形态；最后开展了土壤重金属污染潜在环境风险评价。结果表明：矿区土壤成分主要包括石英、长石、高岭石、蒙脱石等；土壤重金属污染水平由大到小为Zn＞Pb＞Ni＞Cd＞Cu＞Cr＞As；土壤重金属中以残渣态存在所占比例最高的元素是Ni，酸可提取态比例最高的是Zn；土壤重金属的污染指数及潜在生态风险指数整体偏高，单因子污染指数最高的元素是Cd，内梅罗综合污染指数为1 472.98；环境风险系数最高的重金属元素为Cd，环境风险综合指数（RI）高达25 380.63，超过高生态风险阈值211.51倍。

Pollution Characteristics and Pollution Risk Evaluation of Heavy Metals in Soil of Lead-zinc Mining Area

In order to analyze the pollution characteristics and evaluate the pollution risk of heavy metals in soil in lead-zinc mining areas, soil samples in a lead-zinc mining area in Hunan province were collected and analyzed. The mineral compositions were analyzed by X-ray diffraction (XRD) method. The soil samples were digested by microwave digestion instrument, and then the concentration of heavy metals detected by inductively coupled plasma mass spectrometry (ICP-MS). The heavy metal forms were analyzed by method proposed by the European Communities Bureau of Reference (BCR). Finally, the heavy metal pollution potential environmental risk was assessed. The results show that the soil components mainly include quartz, feldspar, kaolinite and montmorillonite, etc. The pollution level for different heavy metals is in the order of Zn＞Pb＞Ni＞Cd＞Cu＞Cr＞As. The heavy metals have different leaching behaviors in different leaching experiments, and Ni possesses the highest proportion of residual state, while Zn has the highest proportion of acid extractable state. The pollution index and potential ecological risk index of heavy metals in soil are high on the whole. Cd possesses the highest single pollution index with the Nemerow comprehensive index of 1 472.98. Cd also possesses the highest environmental risk coefficient with the comprehensive pollution index RI of up to 25 380.63 that exceeds the high ecological risk threshold by 211.51 times.