丹河水系表层沉积物重金属污染及生态风险评价

采用原子吸收分光光度法和原子荧光光谱法,测定了丹河水系干流及主要支流表层沉积物中重金属（Mn、Zn、Cu、Pb、Cd、Cr、Hg、As）的含量,同时用沉积物质量基准法（SQG）和Hakanson潜在生态风险指数法,对重金属的毒性效应、污染程度及潜在生态风险进行了评价,并分析了重金属的主要来源。结果表明,丹河水系表层沉积物中Mn、Zn、Cu、Pb、Cd、Cr、Hg、As的平均含量分别为115.1、18.78、8.46、6.49、2.85、60.6、0.047、14.22mg·kg-1。Cd、As和Cr的含量介于最低效应水平（LE-L）与严重效应水平（SE-L）之间。根据SQG,丹河表层沉积物中重金属含量处于中度污染水平,可能会对河流生物产生一定的毒性效应,而Pb、Cu、Zn则尚无毒性效应。除了As和Cr之外,其他重金属元素之间均呈现较明显的正相关,表明在沉积物中这些重金属的含量具有共同的变化趋势,且具有一定的同源性。工业排污是造成丹河水质恶化的主要原因之一,也是重金属的主要来源。以山西省土壤背景值为参比进行Hakanson潜在生态风险指数评价发现,丹河水系表层沉积物呈现由强至极强的生态风险,其中Cd生态风险最大,Hg、As次之。对单个重金属的潜在生态风险系数和多个重金属的潜在生态风险指数进行分析显示,生态风险较大的样点是高平市、巴公河和水东。研究结果旨在得到单一污染物的环境影响和多种污染物的综合效应的评价结果,为丹河水系沉积物及水体重金属污染防治和决策管理提供科学依据。

Heavy Metal Pollution in the Surface Sediment of Dan River and Its Ecological Risk Assessment

The concentrations of heavy metals（Mn,Zn,Cu,Pb,Cd,Cr,Hg,As）in the surface sediment of Dan River and its main tributaries were determined by using atomic absorption spectrometry（AAS）and atomic fluorescence spectrometry（AFS）,and the toxic effects and sediment pollution assessment were conducted systematically by using Sediment Quality Guidelines（SQG）,Hakanson Potential Ecological Risk Index.Moreover,the underlying source of heavy metal was analyzed.The results indicated that the average concentrations of Mn,Zn,Cu,Pb,Cd,Cr,Hg,As were 115.1,18.78,8.46,6.49,2.85,60.6,0.047,14.22 mg·kg-1 respectively.Base on the SQG,the surface sediment in Dan River was moderately contaminated by Cd,As and Cr since their concentrations were just between lowest effect leve（lLE-L）and severe effect leve（lSE-L）values,which could be result in negative biota effects in the watersheds.Except for As and Cr,other heavy metal elements found the most obvious positive correlation.These heavy metals had a common trend and the same pollution source.Industrial waste was one of the most important anthropogenic emission sources of trace elements and an important source of heavy metals mainly.Compared to the soil background values of Shanxi,the heavy metals in Dan River sediments showed more higher ecological risk,and the ecological risk of the heavy metals,arranged from the highest to lowest pollution degree,was as follows CdHgAsPbCrCuZn.On the basis of analysis of potential ecological risk factor and ecological risk index of the heavy metals,it suggested that Gaoping City,Bagong River,Shuidong were the most polluted sites.This study would provide scientific basis for the prevention,control of pollution,and environmental management in Dan River.