伊敏矿区排土场周围土壤中Cr、Cd形态分析及污染评价

Speciation Analysis and Pollution Evaluation of Cr and Cd in Soils Around in Yimin Mining Area

本文以呼伦贝尔伊敏矿区排土场周围土壤为研究对象,采用改进BCR法提取土壤Cr、Cd化学形态,研究不同土层深度Cr、Cd各形态含量变化规律,并采用单因子污染指数和内梅罗指数评价对该区域土壤Cr、Cd污染进行评价,为进一步研究矿区土壤重金属污染来源和土壤污染修复提供科学依据。实验结果表明:土壤中Cr各形态含量呈现残渣态>可氧化态>可还原态>弱酸提取态变化趋势,各形态含量变化均与土层深度无明显关系;土壤Cd各形态含量呈现弱酸提取态>残渣态>可氧化态>可还原态变化规律,且随着土层深度增加含量明显降低。该区域土壤中Cr残渣态所占比例大于73%,Cr元素处于较稳定状态;土壤中Cd有效态重金属所占比例大于83%,极易被动植物所吸收,潜在生物污染性较大。研究区域土壤中Cd总含量超过呼伦贝尔地区土壤背景值1.37倍,土壤已经受到Cd污染;土壤中Cr总含量接近呼伦贝尔地区土壤背景值,且Cr残渣态含量比例高,土壤未受到Cr污染。土壤中Cr和Cd单因子污染指数Pi分别为0.88和1.38,内梅罗综合指数P综分别为0.91和1.44,研究区域土壤未发生Cr污染,出现了轻微Cd污染。

The soil around the dump in Hulunbuir Yimin mining area was taken as the research object.The chemical forms of Cr and Cd in soil were extracted by improved BCR method,and the changes of Cr and Cd in different soil depths were studied.The single factor pollution index and Nemerow index were used to estimate the pollution of Cr and Cd in the soil of the region,which provided a scientific basis for further research on the source of heavy metal pollution and soil pollution remediation in the mining area.The experimental results showed that the content of Cr in soil showed a trend of residual state>oxidation state>reduction state>weak acid extraction state,and the change of each form content had no discernible relationship with soil depth.The content of various forms of Cd in soil showed dilute acid extraction state>residual state>oxidizable state>reducible state,and the content decreased significantly with the increase of soil depth.The proportion of Cr residue in the soil in this region was greater than 73%,and Cr element was in a relatively stable state.The proportion of Cd available heavy metals in the soil is more than 83%,which are easily absorbed by animals and plants and have great potential for biological pollution.The total Cd content in the soil of the study area was 1.37 times higher than that of soil background value in Hulunbuir,and the soil was polluted by Cd.The absolute content of Cr in soil was close to the background value of soil in Hulunbuir,and the proportion of Cr residue was high,and the soil was not polluted by Cr.Single factor pollution indexes pi of Cr and Cd in soil were 0.88 and1.38,respectively,and the comprehensive index p of Nemerow was 0.91 and 1.44,respectively.No Cr pollution occurred in the soil of the study area,and slight Cd pollution occurred.