内蒙古某铅锌矿区根际土壤重金属污染现状及植物富集特征研究

Current Status of Inter-root Soil Heavy Metal Pollution and Plant Enrichment Characteristics in a Typical Lead-zinc Mining Area in Inner Mongolia

铅锌矿开采带动了内蒙古地区经济的发展,然而开采过程也不可避免地导致了矿区周边的土壤和植被污染。为了给当地土壤污染修复提供理论依据,矿区周边的重金属污染状况亟须客观、准确地评价。本文以内蒙古某个铅锌矿为研究对象,调查了矿区周边不同区域土壤中重金属Zn、As和Pb的含量,使用内梅罗综合污染指数和潜在生态危害指数评价了矿区当前的污染现状,同时分析了该地区优势种植物地上部植株和地下部根系对重金属的富集和转运能力,以筛选具有土壤重金属污染修复潜力的植物。该铅锌矿区的Zn、As和Pb均显著超过风险筛选值和背景值,内梅罗综合污染指数和潜在生态危害指数污染等级都达到了最高级。原生矿Zn和Pb的含量均值分别为915.4 mg/kg和234.3 mg/kg,是风险筛选值3.1倍和1.4倍。铅锌矿的伴生矿As是该地区不可忽视的污染元素,含量范围在150.7~2915.5 mg/kg之间,平均值为712.0 mg/kg,是背景值的113.0倍、风险筛选值的28.5倍。矿区内优势种植物对Zn、As和Pb的富集量均未达到超积累植物的标准,苍耳有作为先锋植物的潜力,对Zn、As和Pb有相对较强的富集和转运能力,但较小的生物量可能会影响修复的效果和时间。研究表明,该地区铅锌矿的土壤Zn、As和Pb污染不仅需要加强工艺提取技术,实现源头上减量,还需要植被和先进人为修复材料添加的联合修复方法来尽快改善当前的污染状况。

Lead-zinc mining has driven the economic development of Inner Mongolia,however,the mining process has also inevitably led to the soil and vegetation contamination around the mining area.In order to provide a theoretical basis for local soil pollution remediation,it is urgent to objectively and accurately evaluate the heavy metal pollution situation around the mining area.Taking a lead-zinc mine in Inner Mongolia as the research object,and the contents of heavy metals such as Zn,As and Pb in the soil of different areas around the mining area were investigated.The current pollution status of the mine site was evaluated by using the Nemero composite pollution index and potential ecological hazard index.At the same time,the enrichment and transport capacity of aerial plants and underground roots of dominant plants in this area were also analyzed to screen plants with the potential for remediation of heavy metal pollution in the soil.The Zn,As and Pb in this lead-zinc mine significantly exceeded the risk screening and background values,and both the Nemerow composite pollution index and the potential ecological hazard index reached the highest pollution level.The average contents of primary ore Zn and Pb were 915.4 mg/kg and 234.3 mg/kg,respectively,which were 3.1 and 1.4 times higher than the risk screening values.The associated ore As of Pb-Zn ore was a non-negligible pollutant element in the area,with the content ranging from 150.7 to 2915.5 mg/kg,and the average value was 712.0 mg/kg,which was 113.0 times of the background value and 28.5 times of the risk screening value.The enrichment of Zn,As and Pb by dominant species plants in the mining area did not reach the standard of super-accumulated plants.The Xanthium strumarium L.had the potential to be a pioneer plant because it had relatively strong enrichment and transshipment capacity for Zn,As and Pb,but smaller biomass may affect the effectiveness and timing of restoration.The results indicated that the soil Zn,As and Pb contamination of the lead-zinc ore in this area requires not only enhanced the process extraction techniques to achieve reduction at the source,but also a combined remediation approach with vegetation and advanced anthropogenic remediation material to improve the current contamination situation as soon as possible.