基于GIS对宁夏某铜银矿区周边土壤重金属来源解析

以中卫市沙坡头区南部崾岘子沟汇水区为研究区，采用网格布点法采集0~20 cm表层土壤样品194份，对Ni、Cu、Zn、As、Ag、Cr、Cd、Hg和Pb这9种重金属元素进行含量测定，采用PMF源解析模型和IDW插值法分析重金属的来源和空间分布，利用ArcGIS空间统计分析工具进行空间自相关和聚类与异常值分析，得到土壤中重金属来源的分布区域.结果表明，研究区Hg、Ag、Cd和Pb平均值分别为背景值的20.48、3.13、2.23和1.12倍，Cd、Cu、Pb和As最大值分别为筛选值的10.92、5.52、2.03和1.39倍，污染较为严重；Cu、Cd、Pb和Hg的变异系数大小为：Cu （283.23%）>Cd （224.77%）>Pb （144.40%）>Hg （67.12%），受人类活动影响密切；PMF源解析得到4个主要污染源：自然母质源（32%）、矿业活动和交通运输综合源（17.1%）、工业活动和大气沉降综合源（40.3%）及农业活动和农田压砂综合源（10.6%），代表元素分别为Cr和Ni，As和Cu，Hg以及Cd；空间统计分析结果表明土壤重金属主要污染源为矿业活动和农业活动，污染严重的区域分布在研究区南部的矿区和研究区东部、中部和西北部的种植区.

Identification of Soil Heavy Metal Sources Around a Copper-silver Mining Area in Ningxia Based on GIS

This study area was based on the catchment area of the Yaoxianzi ditch located in the arid region of western China. A total of 194 topsoil samples of 0-20 cm depth were collected using the mesh distribution method. The contents of nine heavy metals (Ni, Cu, Zn, As, Ag, Cr, Cd, Hg, and Pb) were determined using ICP-MS. The source and spatial distribution of heavy metals were analyzed using PMF and IDW. Spatial autocorrelation and clustering and outlier analysis were performed using the Spatial Statistical Analysis tool of ArcGIS. The main sources and distribution areas of heavy metals in the soil were obtained through comprehensive analysis. In the study area, the average values of Hg, Ag, Cd, and Pb were 20.48, 3.13, 2.23, and 1.12 times the background values, and the maximum values of Cd, Cu, Pb, and As were 10.92, 5.52, 2.03, and 1.39 times the filter values, respectively. The coefficients of variation of Cu, Cd, Pb, and Hg were ordered as Cu(283.23%)>Cd(224.77%)>Pb(144.40%)>Hg(67.12%) and were closely affected by human activities. The heavy metals in the soil around mining areas came from four main sources:natural parent material (32%), the mixed source of mining activities and transportation (17.1%), the mixed source of industrial activities and atmospheric sedimentation (40.3%), and the mixed source of agricultural activity and putting sandy gravel in farmland (10.6%). Cr and Ni, As and Cu, Hg, and Cd could represent these four sources of heavy metal pollution, respectively. The main sources of soil heavy metal pollution were mining activities and agricultural activities. The heavily contaminated areas were distributed in the mining areas in the south of the study area and in the planting areas in the eastern, central, and northwestern parts of the study area.