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    内蒙古废弃钨钼矿区周围土壤重金属污染生态环境评价及成因分析

    Eco-environmental assessment and genetic analysis of heavy metal pollution in the soil around the abandoned tungsten-molybdenum mine area in Inner Mongolia

    • 摘要: 为研究内蒙古赤峰市废弃钨钼矿区周围土壤重金属污染特征、潜在生态风险及成因分析,共采集83份表层土壤样品和6个土壤钻孔。采用ArcGIS空间插值分析方法研究As、Cd、Cr、Cu、Ni、Pb、Mo和Zn的空间分布,构建重金属扰动指数函数研究重金属受人类活动的污染程度,利用地累积指数法验证矿区周围土壤重金属污染程度,通过相关性分析判断重金属来源并讨论污染成因。结果表明:矿区周围土壤As、Cd、Cu、Pb、Zn和Mo平均含量明显高于矿区周边背景值,高含量主要分布尾矿库周围,主要来源为矿山采选活动;Cr和Ni基本无污染,主要来源为母岩风化。通过重金属扰动指数函数计算发现:采用区域背景值对矿区周围进行重金属污染评价夸大了矿山采选活动对矿区周围土壤重金属的污染,矿区周围土壤重金属污染是由于天然重金属富集和采矿活动共同作用下的“双驱动模式”导致,尾矿库周围土壤重金属污染程度随着与尾矿库水平距离的增加和深度的加大而逐渐降低。降水量丰富程度是影响重金属迁移能力的关键因素,该矿处于降水量匮乏地区,尾矿库对周围土壤重金属污染范围有限,对生态环境影响轻微。

       

      Abstract: In order to study the heavy metal pollution characteristics, potential ecological risks and causes of the soil in the abandoned tungsten and molybdenum mine area in Chifeng City, Inner Mongolia, the authors collected 83 surface soil samples and 6 soil borehole samples. The spatial distribution of As, Cd, Cr, Cu, Ni, Pb, Mo and Zn was studied by ArcGIS spatial interpolation analysis. Heavy metal disturbance index was constructed to study the anthropogenic pollution degree. The geo-accumulation index method was used to verify the pollution degree of heavy metals in the mining area. The correlation analysis was used to judge the sources of heavy metals and discuss the causes of pollution. The results show that the average content of As, Cd, Cu, Pb, Zn and Mo in the soil around mining area is obviously higher than the background value around the mining area, and the high content is mainly distributed around the tailings pond, and the main source is mining activities of the mine. Cr and Ni are basically pollution-free, and the main source is the weathering of the parent rock. Through the calculation of the heavy metal disturbance index function, it is found that the use of regional background values to evaluate heavy metal pollution around the mining area exaggerates the pollution of heavy metals by the mining activities of the mine. The heavy metal pollution in the soil around the mining area is caused by the "double-drive mode"under the combined action of natural heavy metal enrichment and mining activities. The degree of heavy metal pollution in the soil around the tailings pond gradually decreases with the increase of the horizontal distance from the tailings pond and the increase of the depth. At the same time, the richness of precipitation is a key factor affecting the migration capacity of heavy metals. However, the mine is located in an area where precipitation is scarce, which makes the tailing pond exhibit a limited range of heavy metal pollution in the surrounding soil and slight impact on the ecological environment.

       

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