褐土中铁的氧化还原与碳素转化

摘要

A Dissimilatory iron reduction,an important microbial process of the degradation of organic matter in anaerobic environment,is closely related to mineralization of organic carbon.Samples of cinnamon soil were prepared into slurry and then incubated anaerobically in dark or under illumination,to study effect of illumination on iron oxides reduction.Water soluble inorganic carbon and total water soluble carbon were analyzed simultaneously to explore relationship between anaerobic redox of iron oxides and carbon transformation under illumination in cinnamon soil.Results show that 55.31％ of the free iron oxides in the soil could be reduced anaerobically under dark regime,and only 38.90％ could under illumination.As Fe(Ⅱ) produced anaerobically could be oxidized by oxygen generated by photosynthesis of cyanobacteria,the reduction rate of free iron oxides was found to be lowered to 7.95％ after 40 days of anaerobic incubation under illumination.The content of soluble total carbon and soluble inorganic carbon increased by 69％ and 246％,respectively,after 40 days of anaerobic incubation in dark,while they both displayed a rising-and-then-declining trend during anaerobic incubation under illumination.When the 40 days of incubation ended soluble total carbon and inorganic carbon was found only 47％ and 70％ higher,respectively,than it was at the beginning of the incubation The content of soluble total carbon was closely related to the content of 0.5 mol L-1 HCl extractable iron,while the content of soluble inorganic carbon was to the content of Fe(Ⅱ) in the soil under the incubation.%采用泥浆厌氧恒温培养的方法,研究了光照对旱作褐土中氧化铁的厌氧还原过程的影响,探讨了土壤中铁氧化物的还原-氧化过程与碳素转化的关系.结果表明,旱作褐土中游离铁氧化物的55.31％可在厌氧避光条件下发生还原,厌氧光照条件下游离铁氧化物的还原率最大仅为38.90％,还原产生的Fe(Ⅱ)可能被蓝细菌中的鱼腥蓝细菌属光合过程产生的氧氧化,40 d培养后其游离铁氧化物还原率低至7.95％.厌氧避光条件下培养40 d后土壤中水溶性总碳、无机碳含量分别增加了69％和246％,厌氧光照条件下水溶性总碳和无机碳则呈现先增加后降低的趋势,40 d培养后仅为反应前的47％和70％.水溶性总碳和无机碳含量分别与Fe(T)和Fe(Ⅱ)含量呈极显著线性正相关关系.