[Effect of iron oxide addition on hydrogen, carbon dioxide and methane geneses in paddy soil]

Paddy soil is an important contributor for atmospheric methane. The methanogenesis is related to the production of acetate, hydrogen and carbon dioxide during the decomposition of organic matter under anaerobic conditions. As electron acceptors, iron (III) oxides can effectively compete with electrons in the transformation of organic matter into methane. Its mechanism maybe relates to the consumption of H2 and CO2. After added ferrihydrite and lepidocrocite, the H2, CO2 and CH4 were determined during the anaerobic incubation of slurries at 25 degrees C for 105 days. The results indicated that the addition of ferrihydrite and lepidocrocite could greatly decrease the concentration of H2, CO2 and CH4, and ferrihydrite had a stronger effect than lepidocrocite. In this system, the balance of organic-C was disturbed, CH4-C and CO2-C were reduced, but the CO3(2-)-C fixed by slurry was greatly increased.