清淤底泥处置中添加粉煤灰/炉渣对重金属生物有效性及毒性的影响

在清淤底泥中添加碱性粉煤灰、燃煤炉渣进行钝化处理后,通过浸出毒性实验、重金属形态分级实验及植物生长实验对底泥基质中重金属的活性及生物有效性进行了研究.结果表明:清淤底泥中添加粉煤灰、燃煤炉渣等碱性物质后显著降低了底泥基质中可溶态重金属含量,其中,交换态、有机结合态Pb、Zn所占比例显著降低;碱性物质的加入缓解了重金属的浸出危害,钝化底泥基质中粉煤灰、炉渣对Cu的稳定率可达90.34%~96.88%;与此同时也抑制了底泥中重金属在植物体内的富集与迁移,降低了重金属的生物有效性.相关性分析表明,底泥基质中交换态重金属含量、浸出浓度、植物茎叶中重金属含量及植物根伸长抑制率之间存在显著正相关关系(p0.01).

The effect of fly ash and alkaline slag on the heavy metals bioavailability and toxicity of dredged sediment

Alkaline fly ash and slag were added to immobilize the heavy metals in dredged sediment. The redistributions and bioavailability of heavy metals in stabilized sediment were determined by the leaching experiment, Tessier fraction distribution experiment and pot experiment. Results show that after adding fly ash and alkaline slag, the content of exchangeable fraction of heavy metals reduced. The percentage of exchangeable fraction and organic fraction of Pb,Zn decreased significantly in stabilized sediments in comparison to sediment control treatment. The alkaline materials reduced the leaching potential and bioavailability of heavy metals. the immobilization efficiency of Cu in stabilized sediments were as high as 90.34%~96.88%, and the heavy metal concentrations in alfalfa overground parts of stabilized sediment treatments were much lower than those of control. There was significant interaction between pH, available heavy metal content, leaching concentration, and heavy metal concentration in the plants (p<0.01).