白银东大沟水体和底泥中重金属污染评价

Contamination situation and evaluation of heavy metal pollution in water and sediments of Dongdagou area,Baiyin

为了给白银东大沟河道生态治理和底泥处理风险评价提供科学参考,分析了东大沟水体中Cu、Pb、Zn、Cd、As、Hg和底泥中Cr、Zn、Pb、Cu、Cd、Hg重金属的含量水平、分布特征及含量变化趋势,并采用内梅罗综合指数法和潜在生态风险指数法分别对水体和沉积底泥中的重金属污染累积程度、潜在风险进行评价。研究结果表明,东大沟水体中6种重金属平均含量在0.005 7～4.796 0 mg/L之间,其含量大小依次为Zn>Cu>Cd>Pb>As>Hg。随水流方向,水体中As含量表现为升高趋势,其余重金属含量则呈显著降低趋势。底泥中6种重金属平均含量在(61.6～5 999.3)×10-6之间,其含量大小依次为Zn>Pb>Cu>Cd>Cr>Hg。东大沟河段底泥中的重金属含量有起伏,但整体表现为随水流方向含量显著降低的趋势。参照相关评价标准,东大沟水体的主要重金属污染物为Cu、Pb、Zn、Cd,其单因子污染程度Cd>Pb>Zn>Cu,综合指数评价表明东大沟水体存在不同程度的污染;底泥主要重金属污染物为Cd、Hg、Pb、Cu,为复合污染,其生态危害风险程度Cd>Hg>Pb>Cu>Zn>Cr,潜在生态风险指数评价表明东大沟大部分河段底泥潜在生态风险指数为严重。

In order to provide scientific reference for the ecological control of the water and the risk assessment of sediment treatment, the authors analyzed the content level, the distribution characteristics and the content change trend of heavy metals such as Cu, Pb, Zn, Cd, As and Hg in water and Cr, Zn, Pb, Cu, Cd and Hg in sediments. The Nemerow Index and the Potential Ecological Risk Index were used to evaluate the accumulation degree and potential risk of heavy metal pollution in water bodies and sediments. The results show that the average content of six heavy metals in water is in the range of 0.005 7~4.796 0 mg/L, and the content exhibits the order of Zn>Cu>Cd>Pb>As>Hg. The content of As in the water body shows an increasing trend with water flow, while the other heavy metals content in water decreases obviously with the water flow. The average content of six heavy metals in the sediments is in the range of ( 61.6 ~5 999.3)×10 ^-6 , with the order of Zn>Pb>Cu>Cd>Cr>Hg. The content of heavy metals in the sediments of the river sections has undulating changes, but the overall change trend is that the content of heavy metals in the sediments decreases obviously with flowing water. The main heavy metal pollutants in Dongdagou water are Cu, Pb, Zn and Cd, and the single factor pollution degree is in order of Cd>Pb>Zn>Cu. The Dongdagou water evaluated by the Nemerow Index shows that there are different degrees of polluted water in the river. The contaminations in sediments are heavy metal pollutants Cd, Hg, Pb and Cu, and the degree of ecological risk is in order of Cd>Hg>Pb>Cu>Zn>Cr. The evaluation of the sediments in Dongdagou by using the Potential Ecological Risk Index shows that the total potential ecological risk index of the sediments in the whole section of Dongdagou is serious.