合肥市饮用水源地沉积物重金属生态风险评价与来源解析

Ecological Risk Assessment and Source Apportionment of Heavy Metals in Sediments of Drinking Water Sources in Hefei City

选取合肥市饮用水源地董铺-大房郢水库沉积物为研究对象,在该区域采集了18个沉积物样品,分别测定了8种重金属Cr、Ni、Cu、Zn、As、Cd、Pb、Hg的质量分数。分别采用沉积物质量基准法和潜在生态风险指数法评估其污染状况及生态风险,并通过多元统计分析和正定矩阵因子模型(PMF)对其可能来源进行解析。结果表明:研究区域Cr、Ni、Cu、Pb、Zn总体质量分数较低;Cd和Hg变异系数较大且所有点位质量分数均超出安徽省土壤背景值,受人为源的影响较大;在空间分布上大房郢水库沉积物Hg、Cd平均质量分数高于董铺水库;董铺水库重金属生态风险程度从高到低依次为Hg、Cd、As、Ni、Pb、Cu、Cr、Zn,大房郢水库重金属生态风险程度从高到低依次为Hg、Cd、As、Pb、Ni、Cu、Cr、Zn,水源地Hg、Cd、As为中等生态风险,其余5种重金属生态风险水平较低。污染源解析结果表明该饮用水源地Hg、Cd、As主要来源为电厂大气污染源和农业源。

Eighteen sediment samples were collected from Dongpu-Dafangying reservoirs,the drinking water source of Hefei City,to determine the total mass fraction of eight heavy metals(Cr,Ni,Cu,Zn,As,Cd,Pb and Hg).The ecological risk of heavy metal contamination in the sediment was evaluated using sediment quality criteria and the potential ecological risk index methods,respectively.Multivariate statistical analysis and positive definite matrix factor analysis(PMF)were applied to assess the possible sources of the heavy metals.Results showed that the mass fraction of Cr,Ni,Cu,Pb and Zn in the sediments were relatively low except for Hg,Cd and As,which exceeded the environmental background values of heavy metals in soils of Anhui Province.The average mass fraction of Hg and Cd in sediments of Dafangying reservoir were higher than those of Dongpu reservoir.The heavy metal ecological risk in the sediment of Dongpu reservoir followed a descending order as:Hg,Cd,As,Ni,Pb,Cu,Cr,Zn,while Hg,Cd,As,Pb,Ni,Cu,Cr,Zn for Dafangying reservoir.Hg,Cd and As had a higher environmental risk among the eight investigated heavy metals in Hefei drinking water source.According to the source apportionment results,Hg,Cd and As in this region were mainly affected by human-made sources,which came from coal combustion in power plant as well as agricultural sources.