DFeRB和SRB对冰封期铁与硫还原的影响研究

铁硫还原对环境中碳、氮、磷等生源要素的环境地球化学行为及重金属等污染物的形态和生物有效性有重要影响,而微生物在铁硫还原过程中起关键控制作用。本文针对北方寒旱区冰封期较长的特点,采用室内模拟研究,重点探究了冰封期异化铁还原菌(Dissimilatory iron reducing bacteria,DFeRB)和硫酸盐还原菌(Sulfate reducing bacteria,SRB)介导的还原过程对铁硫行为的影响以及铁硫还原的耦合关系。结果表明,铁硫共存时,DFeRB和SRB的存在影响铁硫自身的电子传递,使铁和硫的还原过程更为复杂。DFeRB和SRB的还原倾向性存在明显差异。铁硫共存时,DFeRB更有利于铁的异化还原,DFeRB对铁的影响程度强于SRB。无论是DFeRB还是SRB,铁和还原菌同时存在时对硫酸盐还原的促进作用更强。DFeRB和SRB介导下的异化铁还原和硫酸盐还原存在明显的耦合关系,且存在显著的阶段性差异。研究表明冰封期DFeRB和SRB仍具有生物活性及还原能力,且对异化铁还原和硫酸盐还原有明显促进作用。

Effects of DFeRB and SRB on the reduction of iron-sulfur during the ice-bound period

The reduction of iron and sulfur has an important impact on the environmental geochemical behavior of carbon, nitrogen, and phosphorus as well as the species and bioavailability of pollutants such as heavy metals, while microorganisms play a key role in the iron and sulfur reduction process. Based on the characteristics of the long ice-bound period in the cold regions of northern China, this work focuses on the effects of dissimilatory iron-reducing bacteria -(DFeRB -)and sulfate-reducing bacteria(SRB)-mediated reduction processes on the behavior of iron-sulfur during the ice-bound period as well as the coupling relationship of iron-sulfur reduction using simulation studies in the laboratory. The results showed that DFeRB and SRB affected the electron transfer of iron and sulfur when both elements coexisted in the system, making the reduction process of iron and sulfur more complicated. In addition, the reduction tendencies of DFeRB and SRB were obviously different. DFeRB was more favorable for the dissimilatory reduction of iron when iron and sulfur coexisted in the system, and the effect of DFeRB on iron was stronger than that of SRB. Iron and reducing bacteria(DFeRB or SRB) promoted sulfate reduction more strongly when they existed simultaneously. Dissimilatory iron reduction and sulfur reduction mediated by DFeRB and SRB exhibited an obvious coupling relationship and a significant stage difference. DFeRB and SRB retained certain bioactivity and reducibility even during the ice-bound period, and obviously promoted the reduction process of iron and sulfur.