曝气方式对底泥重金属释放的影响

The Influence of Different Aeration Modes on the Release of Heavy Metals in Sediments

曝气是解决水体溶解氧亏缺的主要技术。但曝气后泥水界面溶解氧的变化使得界面处流量流动和物质循环发生改变,沉积的营养盐和重金属会重新释放出来。以扬州市真州镇有机污染水体为研究对象,曝气深度为控制变量,研究不同曝气方式下底泥重金属释放规律。野外试验结果表明,底泥中不同的重金属对曝气的响应也不同,Cd随铁锰共沉淀后底泥Cd出现增加现象,Cu和Fe释放对pH变化敏感,Zn和Pb释放则是H^(+)和共沉淀共同影响结果。从底泥修复效果来看,浅层曝气有利于底泥中重金属释放,减轻底泥重金属污染,修复效果更好。曝气时游离于水体中含氮胶体絮凝沉降于底泥中;而底泥表层氧化物吸磷量远小于厌氧释磷量。

Aeration is one of the ecological restoration techniques to solve the water bodies affected by hypoxia.However,dissolved oxygen variations in water will change energy flow and mass balance of solid-liquid interfaces,which lead to resuspension release of heavy metals adsorbed bottom sediments.Taking an organic polluted water body in Zhenzhou District of Yangzhou City as research topic,the aeration depth as the control variable,this paper studies the release law of heavy metals from bottom sediments under different aeration modes.The results of field experiments show that different heavy metals in the sediments have different responses to aeration.Cd increases with the co-precipitation of Fe and Mn.The release of Cu and Fe is sensitive to the change of pH,while the release of Zn and Pb is coordination effect of H^(+)and co-precipitation of Fe and Mn.From the sediment remediation effect,shallow aeration is conducive to the release of heavy metals of sediments,reduce the heavy metal pollution in sediments.The remediation effect of shallow aeration is better than that of deep aeration.During aeration,nitrogen-containing colloid in water flocculates and settles in sediments.However,the amount of phosphorus absorbed by the oxides in the sediment surface is far less than the amount of anaerobic phosphorus released.