某金属冶炼企业土壤As污染特征及潜在生态风险评价

以某金属冶炼企业原址用地土壤为研究对象，采用单因子污染指数法、地累积指数法、潜在生态危害指数法探讨土壤As污染累积、潜在生态风险和空间分布特征。结果表明：研究区土壤采样点位超标率为98.85%，2.5~14.0 m深度范围土壤As污染较重、潜在生态风险较高，尤以6.0~10.0 m深度范围内相对最高。从As污染成因看，0~1.0 m深度范围土壤As污染主要受企业生产活动影响；1.0~14.0 m深度范围土壤As污染除受企业生产活动影响外，还与大量回填的含As较高的硫铁矿渣、极强碱性土壤环境、土壤渗透性有关。从As污染空间分布特征看，垂直方向上As污染浓度在0~10.0 m深度范围内随深度增加呈升高趋势，地表10.0 m以下随深度增加呈下降趋势。水平方向上，地表以下5.0、10.0、12.0 m剖面深度处As污染羽分布随深度增加呈增大趋势，12.0 m以下呈减小趋势。土壤As污染分层评价结果与地表以下特定剖面深度处土壤As污染评价结果一致性较好，土壤As污染较重的区域潜在生态风险亦相对较高。可见，采用单因子污染指数法、地累积指数法、潜在生态危害指数法综合评价土壤As污染与潜在生态风险，具有较高的可靠性。

As Pollution Characteristics and Potential Ecological Risk Assessment in Soil at a Metal Smelting Enterprise

Taking the soil of the original site of a metal smelting enterprise as the research object,the single factor pollution index method,geo-accumulation index method and potential ecological risk index method were used to discuss the accumulation,potential ecological risk and spatial distribution characteristics of As pollution in soil.The results showed that the percentage of the points exceeding the standard was 98.85%,As pollution and potential ecological risk in soil were relatively high from 2.5 to 14.0 meters in vertical,especially in depth of 6.0 to 10.0 meters.There was a certain degree of cumulative pollution of As in soil from 0 to 1.0 meters below the surface,which was mainly affected by the production activities of enterprise.As pollution in soil from 1.0 to 14.0 meters was not only affected by the production activities of the enterprise,but also closely related to other factors,such as the iron sulfide slag with high As content,extremely alkaline soil environment and soil permeability.The concentration of As increased from the depth of 0 to 10.0 meters,and decreased below 10.0 meters.The distribution of As pollution plumes in depth of 5.0,10.0 and 12.0 meters below the surface increased with the increase of depth,while the distribution of As pollution plumes decreased below 12.0 meters horizontally.The stratified assessment results of As pollution in soil were in good consistent with the assessment results of As pollution at a specific section depth,the ecological risk was also higher in the heavily polluted regions.It could be seen that the evaluation results of As pollution and potential ecological risk in soil were relatively reliable by using single factor pollution index method,geo-accumulation index method and potential ecological risk index method.