广西某铜冶炼场地土壤污染特征及源解析

Soil contamination characteristics and source analysis of a copper smelting site in Guangxi

以广西某铜冶炼场地为研究对象,共采集土壤样品395个,测定场地特征污染pH、Pb、Cd和As含量,基于地统计反距离权重插值法研究场地重金属空间分布特征,通过地积累指数法、内梅罗综合指数法评价了不同场地深度土壤重金属污染程度,运用PMF模型对重金属进行源解析,定量化污染贡献度.结果表明:研究区土壤重金属含量较高,呈明显的块状分布,不同深度土壤As平均含量均超过土壤元素背景值,Pb、Cd和As含量高值区主要分布于场地生产区;在垂向分布特征上,Pb和Cd污染主要集中于土层0~9 m,As的污染区域分布更广更深;Pb、Cd和As均存在地质累积,随着土壤深度的增加,Pb和As累积量均呈降低趋势,Cd积累量在9~22 m土壤深度上存在上升趋势,地质积累指数大小顺序为Cd>As>Pb;研究区土壤总体呈重度污染,风险程度As>Cd>Pb;源解析结果得到4类主要污染源,分别是工业废渣源(75.4%)、矿石冶炼源(95.9%)、污水泄露源(60.4%)和化石燃料燃烧源(64.9%).研究得出的冶炼场地土壤重金属空间分布及富集特征,可为开展土壤污染治理提供理论及数据支撑.

This study took a copper smelting site in Guangxi as the research object,and a total of 395 soil samples were collected.The field work focused on analysing pH and the concentation of characteristic pollutants Pb,Cd,As,and the spatial distributions of heavy metals are investigated based on geostatistics and inverse distance weighting interpolation.This study evaluated the heavy metal pollution level in different soil depths using the geoaccumulation index and the Nemerow comprehensive index method.The PMF model was perform for source apportionment,and the pollution contributions of heavy metals were assessed.The results showed that the heavy metal content in the study area was high and had an obvious blocky distribution.The average As content in soil at different depths exceeded the background value of soil elements,and the high-value areas of Pb,Cd,and As were mainly distributed in the manufacturing area.In terms of vertical distribution characteristics,Pb and Cd pollution were mainly concentrated in the soil layer of 0~9 m,and the As pollution area was more extensive and deeper.Pb,Cd,and As all showed geological accumulation.With the increase of soil depth,the accumulation of Pb and As showed a decreasing trend,while the accumulation of Cd showed an increasing trend in the soil depth of 9~22 m.The size order of geological accumulation index was Cd>As>Pb.The overall soil in the study area was heavily polluted,and the risk level followed the order of As>Cd>Pb.The source analysis identified four main sources of pollution,which were industrial waste residue(75.4%),ore smelting(95.9%),sewage leakage(60.4%),and fossil fuel combustion(64.9%).The spatial distribution and enrichment characteristics of heavy metals in the smelting site soil obtained from the study can provide theoretical and data support for soil pollution control.