不同重金属离子对异化铁(Ⅲ)还原过程的影响

Effects of different heavy metals on dissimilatory iron reduction

以水稻土土壤浸提液作微生物接种液,人工合成的F e(OH)3为唯一电子受体,测定了厌氧培养过程中F e(Ⅱ)浓度的变化,探讨了添加Cu2+,Zn2+,Pb2+,Cd2+,Hg2+和A s5+对铁还原过程的影响及添加不同浓度Cu2+和Hg2+对F e(Ⅱ)浓度的影响,并以土壤中添加不同浓度的Cu2+试验作为对比。结果表明,不同重金属对异化铁还原影响不同,在同一浓度的几种重金属中,Cu2+和Hg2+对异化铁还原抑制最强;不同浓度Cu2+和Hg2+对异化铁还原有不同程度的抑制,主要表现在增加异化铁还原发生前的时间,减慢异化铁还原的速率,当Cu2+和Hg2+浓度增加到一定程度时异化铁还原几乎不发生;水稻土中含有大量铜时,铁还原也会被抑制;添加外源氧化铁可以减轻铜对水稻土铁还原的影响。

In this study,paddy soil water-extraction was incubated anaerobically as inoculum in a mixed culture containing ferrihydrite as sole electron acceptor,the concentrations of Fe（ Ⅱ ） were measured during incubation to assess effects of adding Cu^2＋ ,Zn^2＋ ,Pb^2＋ ,Cd^2＋ ,Hg^2＋ and As^2＋ on dissimilatory iron reduction and observe effects of adding different concentrations of Cu^2＋ and Hg^2＋ on the change of Fe（ Ⅱ ） concentrations. At the same time,different doses of Cu^2＋ were added in paddy soil to compare. The results showed that different heavy metals affected dissimilatory iron reduction differently,at the same concentration,Cu^2＋ and Hg^2＋ restrained dissimilatory iron reduction most. With the increase of the concentrations of Cu^2＋ and Hg^2＋ ,the time before iron reduction increased and the rate of iron reduction decreased. When the contents of Cu^2＋ and Hg^2＋ reached certain level,there was little dissimilatory iron reduction. When there was a large content of copper in soil, iron reduction were restrained too. The restriction of Copper to iron reduction was weakened when the ferric oxide was added to the copper contamination soil.