添加氧化铁对水稻土中H2、CO2和CH4形成的影响

水稻土是甲烷产生的重要源地．厌氧条件下甲烷的形成与有机质厌氧降解产生的乙酸、H2和CO2有关．氧化铁作为电子受体可有效地竞争有机质向甲烷的转化，其抑制作用机理可能与乙酸、H2和CO2的有效消耗有关．通过向水稻土泥浆中添加无定形氧化铁和纤铁矿．分别测定了25℃厌氧恒温培养105d过程中的H2、CO2和CH4的浓度变化．结果表明，添加无定形氧化铁及纤铁矿可导致H2浓度显著降低；无定形氧化铁对H2消耗的影响明显大于纤铁矿；添加不同氧化铁对CO2浓度的影响与H2浓度的变化有相同的趋势；添加氧化铁能显著抑制水稻土中甲烷形成，并导致有机碳的转移发生变化，使得CH4—C显著降低，气相中CO2—C量减少，而由土壤泥浆固定的CO3^2-—C量显著增加．

Effect of iron oxide addition on hvdrogen, 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.