煤矸石堆存区周边土壤重金属污染特征及风险评价

Heavy Metal Pollution Characteristics and Risk Evaluation of Soil Around Coal Gangue Stockpile Area

为探究长期堆存煤矸石中重金属在周边盛行风向土壤里的分布特征及潜在风险,以宁夏枣泉煤矿煤矸石堆存区周边土壤为研究对象,对煤矸石堆存区周边盛行风向土壤中5种重金属(Cu、Zn、Pb、Cr、Mn)总量及重金属赋存形态特征进行深入分析,开展了土壤重金属生物活性分析及评价。结果表明:由于煤矸石的长期堆放、风力、雨水淋溶等,堆存区边缘处重金属(Zn、Pb和Mn)含量较高,且随着距离的增大呈下降趋势;相关性分析中土壤pH值与Zn、Pb含量呈极显著负相关性,与Mn含量呈显著负相关性,与Pb和Cr的可交换态呈显著负相关性,总氮(TN)与Cu的有机质结合态呈极显著负相关性,与残渣态呈极显著正相关性;RAC评价结果表明Pb在土壤中具有较高风险水平,其余重金属潜在风险水平较低。

In order to explore the distribution characteristics and potential risks of heavy metals in long-term storage of coal gangue in the surrounding soil. This study selected the prevailing wind direction soil around the coal gangue stockpile area of the Ningxia Zaoquan coal mine as the research object. The total concentrations and speciation characteristics of 5 kinds of heavy metals(Cu, Zn, Pb, Cr, Mn) in the object soil were analyzed. Meanwhile, the bioactivity of heavy metals was also analyzed and evaluated. The result shows that the concentrations of heavy metals(Zn, Pb and Mn) are high at the edge of the stockpile area due to the long-term storage of coal gangue, wind and rainwater leaching, and decrease with the increase of distance from the stockpile area. The soil pH value has an extremely significant negative correlation with the concentration of total content of Zn and Pb, the commuting states of Pb and Cr, the organic matter binding states of TN and Cu, and the extremely significant positive correlation with the residue state of TN and Cu, respectively. Meanwhile, there is a significant negative correlation between the concentration of total Mn and pH value. The RAC evaluation results show that all the heavy metals except Pb have a low potential risk for soil.