湘江株洲-湘潭-长沙段河床沉积物重金属污染特征及生态风险评价

在湘江株洲-湘潭-长沙(长株潭)河段三地12 处采集河流沉积柱芯12 个,获得沉积物样本384 个,采用地累积指数、潜在生态危害指数等评价方法,系统分析样本中Mn、Zn、Pb、Cu、Cr、Ni等6 种重金属元素含量水平及分布变化特征,对湘江株洲-湘潭-长沙段重金属污染程度及生态风险进行评价。结果表明:湘江长株潭河流沉积物重金属变动趋势变动较大,Cu、Pb、Zn 分布有明显地域规律,Cr、Ni、Mn 分布无明显地域规律。地累积指数显示,除Ni 和Cr 外,长株潭三地都存在Pb、Cu、Zn、Mn污染,其中株洲霞湾段(ZX5-10)Pb 和Zn 达严重污染程度,Mn、Cu 等达到中度或轻度污染程度;湘潭与长沙两地湘江沉积物Pb、Zn 达到中度污染,其余重金属为轻度或偏中度污染水平。潜在生态风险指数显示,株洲段为强生态危害,湘潭段为中等生态危害,长沙段为轻微生态危害。株洲霞湾段湘江沉积物的重金属潜在生态危害应引起有关部门重视。

Pollution Characteristics and Ecological Risk Assessment of Heavy Metals in Surface Sediments in Changsha-Zhuzhou-Xiangtan Reach, Xiang Jiang River, China

The concentration and distribution characteristics of six heavy metals(Mn, Zn, Pb, Cu, Cr, Ni)were analyzed in 384 surface sedi-ments samples fromXiang Jiang River(Zhuzhou-Xiangtan-Changsha Reach, hereinafter referred to as Chang-Zhu-Tan Reach). Heavy metal pollution in the sediments from those areas were analyzed and evaluated by using geo-accumulation index method and potential ecological risk index method. The results indicated that the concentrations of heavy metals in the sediments from Chang-Zhu-Tan Reach which had dif-ferent variation trends, the distribution of 3 heavy metals(Cu, Pb and Zn)was contacted with regular geographic changes, the distribution of the other 3 heavy metals(Cr, Ni and Mn)was contacted with irregular geographic changes. According to the results by using geo-accumula-tion index, there were potentially heavy metals pollutions in Chang-Zhu-Tan Reach, and 4 kinds of metals(Pb, Cu, Zn, Mn)were arrived different degree of contaminations. There were serious pollution of Pb and Zn, mild or moderate pollution of Mn and Cu in Xiawan, Zhuzhou Reach(ZX5-10). In Xiangtan and Changsha Reach, there existed moderate pollution of Pb and Zn, mild or moderate pollution of Cu, Mn, Ni and Cr. The potential ecological risk index indicated that the degree of heavy metal pollution in the surface sediments from Zhuzhou Reach represented high ecological hazard, Xiangtan Reach represented moderate ecological hazard, Changsha Reach represented slight ecological hazard. The results suggested that attention should be paid to the potential ecological risk of Xiawan, Zhuzhou Reach(ZX5-10).