大宝山尾矿库区水体重金属污染特征及生态风险评价

为阐明大宝山槽对坑尾矿坝水体中重金属的污染特征,分析了过滤水、悬浮物和沉积物中重金属的含量,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程度进行评价.结果表明,水体中ρ(Cu)、ρ(Zn)、ρ(Cd)和ρ(Pb)分别高达7.228、41.190、0.178和0.377 mg/L,其中pH和E_h(氧化还原电位)是影响重金属含量的重要因素.悬浮物和沉积物中重金属沿河流断面呈相似的空间分布规律,Cu和Cd污染较为严重.从尾矿库N1采样点至河流下游N4采样点处,重金属沿水流方向呈现溶解态向悬浮态和沉积态迁移特征,而Cu的迁移行为有所不同.据地累积指数法的评价结果,各重金属I_geo(地累积指数)顺序为Cu>Cd>Zn>Pb,Cu和Cd的I_geo平均值分别为4.552和1.605,属重度污染和偏中污染.潜在生态风险指数法评价表明,各重金属危害程度为Cu>Cd>Pb>Zn,Cu和Cd的E_ri(潜在生态危险系数)平均值分别为193.3和143.0,均属强生态危害级别.两种方法均表明Cu和Cd为主要风险元素.该研究区域的RI(生态危害指数)为163.1～576.6,平均值为356.6,属强生态危害级别,相关部门应采取相应措施,加强对该区域污染防治和风险管理. 

Pollution Characteristics and Potential Ecological Risks of Heavy Metals in Water of Tailing Zone in Dabaoshan Mine, Guangdong Province, China

In order to explore the pollution characteristics of heavy metals in the tailing zone of Dabaoshan Mine, the concentrations of Cu, Zn, Cd and Pb in the filtered water,suspension and sediments were measured,and the pollution statuses in the sediments were assessed by geoaccumulation index(I_geo) and Hankanson potential ecological risk index(RI). The results showed that the environmental problem was related tomulti-metal pollution of Cu, Zn, Cd and Pb, in which pH and E_h were the main factors influencing heavy metal concentrations in the water system. The dissolved Cu, Zn, Cd and Pb were found as high as 7.228, 41.190, 0.178 and 0.377 mg/L, respectively. The concentrations of suspended and deposited heavy metals had the similar spatial distribution, which decreased gradually along the river except in the lower reaches, and the Cu and Cd pollution were more serious. Besides, the migration characteristics were dissolved state to suspended and deposited state along the river from sample site N1 to N4, except for Cu. Furthermore, the pollution in the sediments was in order of Cu>Cd>Zn>Pb using I_geo, in which the values of Cu and Cd were 4.552 and 1.605, respectively. Similarly, the ecological risk of heavy metals was in order of Cu>Cd>Pb>Zn from the RI, and the valuesof Cu and Cd were 193.3 and 143.0, respectively, suggesting a strong ecological risk. The study area has become a strong potential ecological risk region, with the average potential ecological risk index being 356.6(ranging from 163.1 to 576.6), indicating that necessary measures should be implemented to strengthen pollution prevention and risk management.