渭河陕西段表层沉积物重金属污染特征及潜在风险

Heavy Metal Pollution Characteristics and Potential Ecological Risk in Surface Sediment of Shaanxi Segment of the Weihe River

为了解渭河陕西段表层沉积物重金属的污染特征,采用ICP-MS分析了13个采样断面表层沉积物中As、Cd、Cr、Cu、Mn、Ni、Pb和Zn 8种重金属的含量,并对其来源和生态风险进行了评价。结果表明:渭河陕西段8种重金属的平均含量顺序依次为Mn>Zn>Cr>Cu>Ni>Pb>As>Cd;除Ni外的其余7种重金属的平均含量均超过陕西省A层土壤背景值。各断面表层沉积物重金属的潜在生态风险指数(RI)介于111.4~7 043.7,其中23.1%的断面有极强生态风险,46.2%的断面为中等生态风险,其余为轻微生态风险。Cd污染最为严重,对各断面的潜在生态风险介于较强生态风险与极强生态风险之间,对RI的贡献平均为85.2%;其余7种重金属在所有断面均属于轻微生态危害。渭河陕西段表层沉积物As、Cd、Cu和Zn主要为工业与农业来源;Cr和Ni主要为自然来源;Pb和Mn与城市污水和交通污染来源有关。

In order to understand the pollution characteristics of heavy metals in surface sediments of Shaanxi segment of the Weihe River,the concentrations of 8 heavy metals including As,Cd,Cr,Cu,Mn,Ni,Pb and Zn in surface sediments of 13 sampling section were analyzed by inductively coupled plasma mass spectrometry（ICP-MS） and their potential ecological risks were evaluated.The results indicated that the average concentration level of heavy metals in sediments followed the order：Mn 〉Zn 〉 Cr〉 Cu〉 Ni〉 Pb〉 As 〉 Cd.The concentrations of 8 heavy metals,except Ni,were above the corresponding soil background values for Shaanxi.The potential ecological risk indexes（RI） of 8 heavy metals at all sampling sites were between111.4 and 7 043.7,including 23.1% sampling sites posed serious potential ecological risk,46.2% sampling sites posed moderate potential ecological risk,and the rest sampling sites posed low potential ecological risk for the River.Cd,which potential ecological risk was from higher potential ecological risk to serious potential ecological risk and contributed 85.2% of the total potential ecological risk,was found as the most polluted heavy metal in the River.The rest of 7 heavy metals all posed a low potential ecological risk at all sampling sites of the River.Source analysis suggested that,As,Cd,Cu and Zn are derived from the industrial and agricultural sources,Cr and Ni are derived from the Natural sources,Pb and Mn are derived from urban sewage and vehicle pollution sources.