表层沉积物重金属生态风险评价——以郑州市东风渠为例

Ecological Risk Assessment for Heavy Metal in Surface Sediments——Taking of Dongfeng River in Zhengzhou as an Example

选择绿藻“水华”污染严重的郑州市东风渠金水段表层沉积物作为研究对象,采用消解法、电感耦合等离子体质谱法(ICP-MS)分析沉积物中Cd、Pb、Ni、Cu、Cr、Zn含量,采用原子荧光光谱法(AFS)分析Hg和As含量,运用Hakanson潜在生态风险指数法评价沉积物中8种重金属的生态风险。研究发现:1)沉积物中Hg、Cd、Pb、Zn含量超过土壤质量二级标准,超标倍数分别为1.71倍、0.85倍、2.94倍、0.09倍,Pb超标倍数最大。2)8种重金属平均潜在生态风险中,Hg为强生态风险,对潜在生态风险指数(E_(RI))的平均贡献率为56.1%,是主要的致险因子;Cd为中等生态风险,对E_(RI)的平均贡献率为28.5%;其他重金属为轻微生态风险。结果表明:郑州市东风渠金水段表层沉积物中的重金属具有潜在的生态危害性。对污泥养分进行间接利用,避免产生二次污染,是改善生态环境、促进环境良性循环的良策。

The surface sediments in Jinshui section of Dongfeng River in Zhengzhou city,which is seriously polluted by green algae"water bloom",are selected as the research object.The contents of Cd,Pb,Ni,Cu,Cr and Zn in the sediments are analyzed by digestion method and Inductively Coupled Plasma-Mass Spectrometry(ICP-MS),the contents of Hg and As are analyzed by Atomic Fluorescence Spectrometry(AFS),and the ecological risks of 8 heavy metals in the sediments are evaluated by Hakanson potential ecological risk index method.The results are as follows:1)The contents of Hg,Cd,Pb and Zn in the sediments exceed the secondary standard of soil quality,and the exceeding multiples are1.71 times,0.85 times,2.94 times and 0.09 times respectively,with Pb exceeding the maximum.2)Among the average potential ecological risks of 8 heavy metals,Hg is a strong ecological risk,with an average contribution rate of 56.1%to the potential ecological risk index(E_(RI)),which is the main risk factor;Cd is a moderate ecological risk,with an average contribution rate of 28.5%to E_(RI);other heavy metals are slight ecological risks.The results show that the heavy metals in the surface sediments of Jinshui section of Dongfeng River in Zhengzhou have potential ecological hazards.Indirect utilization of sludge nutrients to avoid secondary pollution is the good strategy to improve the ecological environment and promote a virtuous cycle of the environment.