混合菌对表层沉积物中重金属形态及生物有效性的影响

采用改进的Tessier连续萃取法对表层沉积物中重金属(内源体系:Fe、Mn、Cu、Zn和Pb;外源体系:掺杂Cu、Zn和Pb后的Fe、Mn、Cu、Zn和Pb)一定时间(45d)内的形态分布进行分析,探讨了混合菌对体系中重金属形态及生物有效性的影响。混合菌的加入促进了沉积物中Fe向可交换态、碳酸盐结合态的转变,Fe的生物有效性显著提高;混合菌的掺杂导致了Mn向稳定态的移动,体系中Mn的各形态除可交换态含量均有所提高,且混合菌可以提高Mn的生物有效性;混合菌的存在增加了内源体系中Zn的铁锰氧化态稳定性,外源体系中混合菌的添加促进了其活化作用,与混合菌前33d降低金属有效性相矛盾;混合菌加入使内源体系中Pb残渣态和外源体系中有机质结合态升高,与混合菌加大Pb的有效性不吻合;混合菌可导致内源体系Cu的铁锰氧化物含量增加和铁锰氧化物态下降、Cu的生物有效性提高,而外源体系中前Cu的碳酸盐结合态上升,混合菌降低了Cu生物有效性。

Impacts of Mixed Bacteria on the Fraction of Heavy Metals and Their Bioavailability in the Surface Sediment

The distribution of heavy metals（Fe,Mn,Cu,Zn and Pb） was analyzed through modified sequential extraction procedure during a period of 45days in the native system and exogenous system in the surface sediment mixed with Cu,Zn and Pb respectively,which was estimated to investigate the impacts of mixed bacteria on the fraction of heavy metals and their bioavailability.The results showed that the participation of mixed bacteria in sediment promoted the transition of Fe changing into the exchangeable fraction and carbonate-bound fraction,meanwhile the bioavailability of Fe significantly increased;the doping of mixed bacteria led the shifting of Mn to the stable fraction,an increasing apart from in exchangeable Mn was observed in the system,the bioavailability of Mn was improved also;the existence of mixed bacteria increased the stability of Fe/Mn-oxides fraction of Zn in the native system,the activation of Zn existing in the exogenous system was promoted,which was in contradiction with its performance of the first 33 days;mixed bacteria increasing the residual fraction of Pb in the native system and its organically-bound contents in the exogenous system was not inosculation with the role that mixed bacteria can increase the validity of Pb;in the native system,mixed bacteria increased the contents of Fe/Mn oxidation of Cu and its bioavailability while declined its Fe/Mn-oxides fraction,while in the exogenous system,mixed bacteria increased the carbonate-bound fraction of Cu but lowered its bioavailability.