典型硫化物矿尾矿区及周边土壤Cd、Cu污染及其生物有效性研究

The study of characteristics and bioavailability of Cadmium and Copper pollution in soil in typical sulfide mine tailings and surrounding area

选择典型金属硫化物矿山尾矿库及周边耕地为研究对象,系统采集尾矿下游土壤剖面样品31件。采用ICP-MS分析Cd、Cu等重金属全量,并按照BCR三步法提取土壤剖面样品Cd和Cu元素的弱酸提取态、还原提取态、氧化提取态和残渣态4种形态。运用地累积指数方法和RAC风险指数编码方法分别评价研究区土壤Cd和Cu污染程度及其生物有效性。结果表明:研究区土壤Cd和Cu污染主要为轻微-中度污染;尾矿库区Cd和Cu的RAC值均较高,显示为中等以上环境风险特征;土壤中Cd、Cu元素的形态及RAC值随着距尾矿库的距离增加及土地利用方式的变化,则表现出不同特征。总体上,Cd、Cu元素生物有效性随着距尾矿库距离增加呈现先降低后增高的趋势。

In order to prove up the accumulation characteristics and its bioavailability of Cadmium and Copper in soils around the sulfide mine tailings,a total of 31 soil profile samples in the survey region were systematically collected. The method of inductively coupled plasma mass spectrometer( ICP-MS) was adopted to analyze the elements of Cd and Cu;and the species of the heavy metals Cd and Cu in soil,BCR three-step continuous extraction method was used to analyze acid leaching state,reduced state,oxidation state and residual state. Geocumulative index method was adopted to make an evaluation on the degree of heavy metal pollution in soil;and the bioavailability of Cd and Cu was evaluated by the risk assessment code method( RAC). The results showed that the pollution levels of Cd and Cu in the soil in the study area were mainly mild to moderate. The morphology and RAC values of Cd and Cu elements in the soil showed different characteristics with the increase of the distance from the tailings pond and the change of land use. In general,the bioavailability of Cd and Cu elements in soils decreased first and then increased with the increase of distance from the tailings pond.