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

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.