某高纬高寒铜矿区土壤重金属的时空变异及迁移规律研究

在收集整理高纬高寒地区某铜矿区以往监测资料和开展的动态监测研究的基础上,对近12年来研究区表层土壤重金属As、Cd、Cr、Cu、Hg、Mo、Ni、Pb和Zn的时空变异趋势进行对比分析,且定量计算了土壤重金属的累积速率。分析结果表明,堆浸场的Cd、Cu含量在尚未开始堆浸时就已超过国家土壤II级标准限值,年均增长速率又较快,因而此处土壤恶化的可能性较大,应引起足够的重视。而尾矿库和排土场处,除了Ni具有较高的超标风险外,其他元素的环境容量相对较大。堆浸场下游的表层土壤中Cr、Zn、Ni、Pb、Cr⁶⁺、Cd和Cu元素的横向迁移距离相对较短,而As、Hg和Mo元素横向迁移距离略长,更容易随堆浸液排放向下游运移。剖面土壤样品中Cu、Zn、Cr、Cd的含量随着深度的增加而降低,表土中重金属含量高于深层土壤样品,呈现出在冻土层的冻结锋面上富集的规律。

Research on the Spatiotemporal Variation and Migration Rule of Soil Heavy Metals in a High Latitude Alpine Copper Mining Area

Based on collecting and arranging the previous monitoring data and dynamic monitoring research in a high latitude alpine copper mining area, the spatiotemporal variation trends of heavy metals of As, Cd, Cr, Cu, Hg, Mo, Ni, Pb and Zn in the surface soil of the study area in the past 12 year were compared and analyzed, and the accumulation rate of heavy metals in soil was quantitatively calculated. The analytical data showed that severe attention should be paid to the large possibility of soil deterioration due to the Cd and Cu contents of the heap leaching field had exceeded the national soil level II standard limit when the heap leaching had not yet started, and the annual average growth rate was faster. Comparatively, there was large soil environmental capacity for heavy metals except Ni at tailing reservoir and dump site. The transversal migration distance of Cr, Zn, Ni, Pb, Cr6+, Cd and Cu was shorter than As, Hg and Mo at downstream of heap leaching field. Elements with longer moving distances were more likely to migrate downstream with heap leaching. The profile soil sample content of Cu, Zn, Cr and Cd decreased with the increasing of depth, and the heavy metal content in the topsoil was higher than that in the deep soil samples which shown the law of enrichment on the frozen front of permafrost.