曝气对河流沉积物中重金属Cu,Pb,Zn和Cd释放的影响

采用模拟实验研究了长春市伊通河沉积物中重金属Cu,Pb,Zn和Cd在曝气条件下的释放规律, 利用Tessier连续萃取法分析曝气前后沉积物中重金属的形态变化. 结果表明, 4种重金属的释放速率和过程各不相同, Zn的释放速率远远小于Pb和Cd, Cu在整个实验过程中浓度变化缓慢. Pb和Zn在曝气一段时间后均出现再吸附或共沉降现象. 所研究样品的金属释放出现峰值时间较快, 存在着较大的生态风险性. 沉积物中的重金属经过曝气后也由原来相对稳定的存在形态逐渐向生物易于吸收的结合态转化, 增加了重金属的生物毒性.

Effect of Aeration on Heavy Metals Cu,Pb,Zn and Cd Release from River Sediment

Effect of aeration on the release of Cu,Pb,Zn and Cd from the sediment of the(Yitong) River in Changchun was studied by simulation experiment,and the morphological changes of the heavy metals before and after aeration in sediment were analyzed too.The results show that the solubilisation kinetics of Cu,Pb,Zn and Cd differ from one metal to another,Zn release is more slowly than those of Pb and Cd,and the concentration of Cu in solution changes slightly.The re-adsorption or co-precipitation processes of Pb and Zn occur after a period of aeration.The concentration peaks of the heavy metals in the solutions appeare more rapidly,which means that the sediment has more ecological risks.The heavy metals in the sediment change from more stable forms to those easily assimilated by microorganisms,which increases the heavy metals toxicity to them.