快速城市化区域河网沉积物重金属污染风险评价与管控对策

为研究快速城市化区域河网沉积物重金属污染特征和生态风险,调查了研究区域具有代表性的5条河道,共采集了19份表层(0～10 cm)沉积物样品,重点分析Cd、As、Pb、Cr、Cu、Zn、Ni和Hg共8种重金属的含量,并评价其生物毒害效应、污染水平和生态风险.结果表明,8种重金属的含量范围分别为:0.29～3.33、6.10～42.40、20.50～149.00、19.60～196.00、15.40～437.00、69.10～560.00、15.80～86.70和0.04～0.61 mg·kg~(-1),其中Cd、Cu和Zn平均含量分别为研究区背景值的28.40、7.20和5.80倍,超当地背景值,情况较为显著.8种重金属含量水平多位于沉积物物质基准值TEC-PEC之间,产生生物毒害效应的可能性不容忽视,63.16%的点位平均可能效应浓度商Q值大于0.5,表明大部分点位中重金属的复合污染已经对底栖生物产生了毒害效应;地累积指数和潜在生态危害评价认为Cd、Cu和Zn的污染水平和生态风险较高,其中Cd对评价结果的贡献率最高.基于以上分析认为,研究区域沉积物重金属污染风险水平较高,其中Cd毒性较大且污染显著,值得重点关注,研究区域重金属污染防治和管理应针对Cd展开.

Risk assessment and management of heavy metals in river sediments from the rapid urbanization region of China

To explore the pollution characteristics and ecological risks of heavy metals in river sediments from a rapid urbanization area in South China, five representative watercourses were selected, and 19 surface (0~10 cm) sediment samples were collected to analyze the concentrations of heavy metals including Cd, As, Pb, Cr, Cu, Zn, Ni, and Hg, pollution levels, toxic effects and ecological risks respectively were then evaluated. The results show that the concentration of the eight heavy metals were in the ranges of 0.29~3.33, 6.10~42.40, 20.50~149.00, 19.60~196.00, 15.40~437.00, 69.10~560.00, 15.80~86.70 and 0.04~0.61 mg·kg^-1, and the average concentrations of Cd, Cu, and Zn was respectively 28.40, 7.20, and 5.80 times of the background level in the soil of Guangdong Province. Cd, Cu, and Zn were the major pollution factors. The levels of heavy metals were mostly located in the TEC-PEC value of consensus-based sediment quality guidelines. thus, the possibility of biological toxicity effects cannot be ignored. the mean probable effect concentration quotient of 63.16% of samples were greater than 0.5, which illustrated that the combined pollution of heavy metals had caused biological toxic effects. The geo-accumulation index and potential ecological risks index indicated that the pollution levels and ecological risks of Cd, Cu and Zn were higher than other heavy metals, and Cd had the highest contribution to the evaluation results. Based on the above analysis, it was considered that the heavy metal pollution risks of sediments in the research area were high.Cd showed the highest biological toxicity and was the main pollution factor in the studied area to bring attention. Effective prevention measures and managements should be taken for improving the ecological environment.