湘江衡阳段沉积物中铊等重金属的污染特征及其生态风险评估

湘江是我国重金属污染最重的河流之一。为了更全面了解湘江衡阳段表层沉积物重金属污染现状及其潜在生态风险,在前期相关研究基础上,分析了重金属Tl及其他4种重金属(Mn、Co、Ni和V)的含量水平和分布特征,并采用地累积指数法和潜在生态风险指数法对沉积物中重金属污染现状和潜在生态风险进行了评价。结果表明,湘江衡阳段表层沉积物中Tl和Mn有一定程度的累积和污染,其含量分别为0.12～2.09mg·kg-1和234～4580mg·kg-1。由于Tl具有较强的毒性响应,其潜在生态风险不容忽视。综合前期相关研究结果,研究区域中10种重金属总潜在生态风险指数(RI)为27.8～6266,约70%采样点具有重度生态风险,其主要风险来源于Cd和Tl。

Distribution and Risk Assessment of Thallium and Other Metals in Sediments from Hengyang Section of Xiangjiang River

Xiangjiang River is one of the highly heavy-metal polluted rivers in China. To obtain comprehensive evaluation about the pollution status of heavy metals and their potential ecological risks, the levels and distribution of thallium (Tl) and four other heavy metals (Mn, Co, Ni and V) in surface sediments from Hengyang section of Xiangjiang River were analyzed based on our previous study. The potential ecological risks of these heavy metals were calculated using index of geoaccumulation (Igeo) as well as Hakanson potential ecological risk index (RI). Results indicated that surface sediments from Hengyang Section of Xiangjiang River were polluted by Tl and Mn to some extent, with concentrations ranging from 0.12~2.09 mg·kg^-1 and 234~4 580 mg·kg^-1, respectively. Much more attention should be paid to the ecological risk from Tl due to its high toxicity. Combined with our previous study, the total RI values of 10 heavy metals in the studied area varied from 27.8~6 266, among which about 70% sampling sites exhibited high ecological risk. The ecological risk was mainly caused by Cd and Tl.