三峡库区土壤铁异化还原及其对铁形态影响

Dissimilatory iron reduction processes of soil from Three Gorges Reservoir area and its effect on chemical form of Fe

采用三峡库区紫色土和黄壤在N2覆盖下进行淹水恒温(25℃)厌氧培养,对土壤淹水铁异化还原及其对铁形态转变的影响进行研究。实验结果表明,土壤淹水厌氧培养过程,pH向中性转变,体系从氧化环境转入还原环境,黄壤氧化还原转换趋势更为明显。黄壤Fe(Ⅱ)增加趋势明显,Fe(Ⅱ)含量达到3 495.21mg/kg,紫色土为536.44mg/kg,而无菌对照土壤Fe(Ⅱ)含量无增加趋势,证实铁的异化还原过程是受微生物活动驱动。土壤铁从Res-Fe向Oxide-Fe活化,同时土壤Fe(Ⅱ)的含量与Oxide-Fe含量呈显著正相关,说明铁形态的改变是受铁的异化还原作用所导致的。

Purple soil and yellow soil from Three Gorges Reservoir area are submerged and incubated under a nitrogen atmosphere at constant temperature（25℃） to study the dissimilatory iron reduction processes and its effect on chemical form of Fe.The results show that pH and ORP decrease with the transition of soil redox condition,and it is especially obvious for yellow soil.The content of Fe（Ⅱ） increases to 3 495.21 mg/kg for yellow soil and 536.44 mg/kg for purple soil.There are no obvious changes of redox condition and Fe（Ⅱ） for sterile soil.It suggests that dissimilatory iron reduction should be driven by metabolic activity of microbe.With the transition of soil redox condition,the content of oxide-Fe increases significantly,and the content of Fe（Ⅱ） and oxide-Fe are significantly and positively correlated,which indicate that transformation of Fe speciation is the result of dissimilatory iron reduction.