某尾矿库土壤重金属污染情况检测与环境风险评价

Detection and environmental risk assessment of heavy metal contamination of soil in a tailings pond

本研究基于电感耦合等离子体质谱检测技术,探究不同样品前处理方法对土壤中重金属定量的影响,建立了一种准确快速的土壤重金属污染筛查方法。该法采用硝酸-盐酸提取法以盐酸:硝酸=3:1溶液浸提重金属,能够稳定提取易挥发性的砷(回收率95%~105%)。采用该筛查方法对某尾矿库场地不同空间位点土壤样品中的铜、铅、镍、砷、镉5种重金属元素进行定量检测,以评估该尾矿库重金属分布情况及污染风险。结果表明该尾矿库内存在不同程度的Pb、As和Cd污染,并且单因子污染指数和内梅罗综合指数均指示存在As的重度污染。其次污染情况还表现出水平和垂直方向上的分布趋势,尾矿库入口和中段污染程度较高而末段污染程度低;土壤表层(0~0.5m)重金属检出值较低而深层(0.5~4.0m)检出值较高。以上结果说明该尾矿库存在严重的重金属污染,并且污染可能在降雨等因素作用下扩大范围和深度,提高治理难度,因此因及时采取措施对已污染区域进行整治。

In this study,based on the inductively coupled plasma mass spectrometry(ICP-MS)detection technique,the effects of different sample pretreatment methods on the quantification of heavy metals in soil were investigated.An accurate and rapid screening method for soil heavy metal contamination was developed.This method employed a nitric acid-hydrochloric acid extraction procedure,utilizing a hydrochloric acid to nitric acid ratio of 3:1,to leach heavy metals.It was capable of stably extracting the volatile arsenic with a recovery rate of 95%-105%.Using this screening approach,we quantified five heavy metal elements,namely Cu,Pb,Ni,As,and Cd,in soil samples from different spatial points of a particular tailings storage facility to assess the distribution and contamination risk of heavy metals within it.The results revealed that there were varying degrees of Pb,As,and Cd contamination in the facility.Both the single pollution index and the Nemerow comprehensive index indicated severe arsenic contamination.Moreover,the contamination showed both horizontal and vertical distribution trends,the entrance and middle sections of the tailings facility were more heavily polluted than the end section.Additionally,the surface soil layers(0-0.5m)exhibited lower heavy metal detection values compared to the deeper layers(0.5-4.0m).These findings highlight the serious heavy metal contamination present in the tailings storage facility.Given the potential for pollution to expand in scope and depth due to factors such as rainfall,remediation becomes more challenging.Therefore,timely measures should be taken to address the affected areas.