草原煤矿开采区土壤重金属污染分布特征及影响因子

Analysis of the influential factors and the heavy metal content distribution in the soil in prairie coal-mining regions

针对鄂尔多斯市伊金霍洛旗典型能源开发区,以土壤重金属污染为切入点,通过对土壤不同层次8种重金属质量比的分析,探讨了矿山开采对土壤重金属的影响。结果表明:煤矿开采区周边土壤重金属质量比受采矿影响较大,利用表层与深层质量比的比值Ri来表征重金属在垂直方向上的富集特点,总体上表层重金属富集显著;通过单因子指数法(Pi)、内梅罗综合污染指数法(PN)及地积累指数法对研究区域土壤重金属污染状况进行综合评价,采矿区周边土壤总体污染程度较轻,各重金属污染程度从大到小依次为镍、铜、铅、锌、镉、砷、铬、汞,铅、铜和镍,表层质量比平均值均大于当地背景值;土地利用类型对土壤重金属质量比的影响较大,利于重金属富集的土地利用类型排序为裸地、旱地、水浇地。

This paper aims to find out the impact of mining slag on the different concentration contents of the heavy metals in the soil, including their distributive regularity, the influential factors and the contamination hazards assessment. For the study purpose, we have chosen the typical Yinjinhuoluo Energy Development Zones near the city of Erdos as a case study sample. In proceeding with our study, we have chosen seven sampling sites a- round the mining area both from the surface and deep levels. In accordance with the analysis of the eight heavy metal contents of the samples, we have identified and determined that the heavy metal contents vary significantly in the soil surrounding the coal mining zone. The average results of the vertical ratio of Ri, which is characteristic for judging the distribution of such metal contents in the vertical direction, indicating that the surface heavy metal contents are greater than those in the deep levels. At the same time, we have discovered the statistical data needed for the evalu- ation of the heavy metal contamination risks. Calculating the single factor pollution index （Pi）, the Nemerow integrated pollution index （PN） and the Index of geoaccumulation （Igco） of the soil heavy metal contamination of an area through a comprehensive study, we have worked out that the area under the investigation belongs to the slightly contaminated one with the contamination degree being in the following descending order： Ni 〉 Cu 〉 Pb 〉 Zn 〉 Cd 〉 As 〉 Cr 〉 Hg. The calculation results indicate that the soil around the mining area has been polluted, with its content of Cu, Pb and Ni exceeding the standard ratio by 0. 151,0. 111 and 0. 245. Comparing the different influential factors of heavy metal contaminations, we have resorted to the Pearson correlation coeffi- cient for our analysis, whose results prove that different types of land uses have brought about profound impacts on the heavy metal contents in the soil, to be precise, the heavy metal enrichment to the soil accounts in the following descending order： bare land 〉 dry land 〉 irrigable land. In addition, the organic contents in the soil and the distance between the area under study and the high- way traffic area also influence the distribution of heavy metals to some extent.