北河流域土壤重金属污染风险评价及影响因素分析

Risk Assessment and Impact Factor Analysis of Soil Heavy Metal Pollution in Baihe River Basin

土壤重金属污染的风险评价及影响因素研究是环境管理的重要基础工作。本文基于GIS和地统计学,采用潜在生态风险指数法和概率克里格法等研究了四川北河流域土壤Hg、As、Pb、Cr污染状况及影响因素。结果表明,Hg是该流域土壤4种元素中生态风险最大的致险元素,其余3个元素的生态风险等级均为轻微;综合考虑4种元素的潜在生态风险均为轻微。区内土壤Hg的生态风险最大,土壤As、Pb、Cr的生态风险等级均为轻微。综合4个元素全部样点的潜在生态风险均为轻微。区内土壤Hg、Pb和Cr呈条带状或团块状由东向西逐渐增加,而As分布则相反;西北部土壤Hg超标概率最大（0.25~0.55）。5种母质的Pb和Cr含量差异显著（P〈0.05）。潮土Hg、Pb显著高于其它3种土壤。土壤p H值与4种重金属含量呈极显著相关（P〈0.01）。村庄和工业用地的Hg和Pb含量明显高于水田和园地（P〈0.05）。

Risk assessment and impact factor analysis of heavy metal pollution is key step in soil quility management. Based on GIS and geostatistics,the pollution risk evaluation of soil Hg,As,Pb,Cr and identification of their impact factors in the Baihe River Basin,Sichuan were conducted in this paper. According to the background values of Soil Environmental Quality Standard in China,Hg was the crucial factor for the eclogical risk of soils,and As,Pb and Cr demonstrated slight eclogical risk. Moreover,all soil sample points showed slight potential ecological risks. In the basin,the concentrations of Hg,Pb and Cr showed zonal increase from east to west; on the contrary,As concentrations decreased from east to west. The probability of soil Hg concentrations exceeding the criterion of class Ⅱof Soil Environmental Quality Standard was 0. 25- 0. 55 in the northwest. The concentrations of Pb and Cr demonstrated significant differences in the soils from the various parent materials（ P 〈0. 05）. The Hg amd Pb concentrations in Fluvo-aquic soils were higher those in yellow earth,purple soil and paddy soil（ P〈 0. 05）. The concentrations of the four heavy metals displayed highly significant relationships with soil p H（ P〈 0. 01）. The concentrations of soil Hg and Pb in village and industrial lands showed obviously higher than those in paddy field and garden plot.