环境条件变化下汾河水库沉积物中重金属形态分布特征及潜在生态风险评价

对汾河水库沉积物中重金属的污染特征和潜在生态风险评价结果表明:汾河水库沉积物中Cd含量为11.42±2.84mg/kg,高于中国湖泊底泥重金属含量背景值。沉积物中Cd的单项潜在生态风险系数远大于其它重金属,高达2346.57,具有极强的生态危害性;而Zn、Cr和Cu只显示出轻微的生态危害性,故Cd是导致汾河水库沉积物中重金属的潜在生态风险增强的主要贡献者。室内模拟沉积物经历好氧和厌氧等环境条件下,并用EDTA铵盐溶液单一提取法和BCR连续提取法分别研究了汾河水库沉积物中Cd、Zn、Cr和Cu等重金属的形态分布特征;结果表明:在好氧条件下,Cd的形态分布特征变化最为明显,具有潜在环境效应的Cd含量所占总量的比例上升至52.15%;用EDTA单一提取法测定结果表明:生物有效态Cd含量占总量的比例(B/T)在好氧处置后最高,达30.37%;上述试验结果进一步证明了沉积物中Cd具有强烈的潜在生态风险和较高的生物有效性。

The Impact of the Redox Conditions on the Speciation of the Heavy Metals in the Sediment of the Fenhe Reservoir and Their Assessments of the Potential Ecological Risk

The research on the pollution characteristics and the assessments of the potential ecological risk of the heavy metals in the superficial sediment of the Fenhe reservoir showed that the concentrations of Cd is 11.42±2.84mg/kg,higher than that of the background value in lake sediment in China;the potential ecological risk index(RI) of Cd in the superficial sediment reached to 2346.57,which was higher than other heavy metals such as Cr,Cu and Zn.The high content of Cd implied its serious ecological risk.The influence of the redox conditions on the speciation and bioavailability of the heavy metals were investigated by the BCR sequential extraction and EDTA single extraction respectively.The results of the experiment showed that the speciation and bioavailability of the heavy metals in the superficial sediment were changed after having been underwent reductive or oxidative condition.The change of the speciation of the different fraction of Cd was the most obvious than other heavy metals,and the percentage of its fractions which have potential environmental effect had been increased to 52.15%.The EDTA single extraction experiment showed that the percentage of the bioavailable fraction of Cd in sediment was the highest(30.37%),when the sediment was in oxidative conditions.The above extraction experimental results could further prove the fact that the Cd showed very high ecological risk.