Dissimilatory iron reduction and potential methane production in Chagan Lake wetland soils with carbon addition

Dissimilatory iron reduction is increasingly becoming recognized as an influential process in freshwater sediments, coupling with carbon cycling. To evaluate the influence of organic matter addition on the reduction rates and dynamics of Fe(III) in wetland soils in Chagan Lake, soil slurry and microbial anaerobic incubation studies were conducted by adding a soluble and redox-active quinone (anthraquinone-2,6-disulphonate, AQDS), glucose and sodium pyruvate. In soil slurry experiment, glucose was added as a single doze and a pulsed input over time. Pulsed glucose addition promoted DIR, particularly in the later incubation stage. The addition of different forms of carbon significantly affected DIR in the inoculation experiment, and the addition of pyruvate increased DIR more than that of glucose in the wetland soil. The AQDS dramatically stimulated the potential DIR by 480-fold. A negative relationship was observed between pH and DIR. Besides, potential methane production was inhibited by the addition of ferrihydrite. These findings provide insight into the connection between iron and carbon input and emission.