沼泽产甲烷能力和途径差异的机制

Mechanisms of Variation of Potential and Pathway of Methane Production in Mires

土壤中甲烷的形成有 2条途径 :乙酸发酵和H2 /CO2 还原。比较而言 ,乙酸发酵产甲烷的能力强于H2 /CO2 还原。在特定环境中 ,何种产甲烷途径占优势取决于底物尤其是活性有机碳含量 ,而新形成的有机碳尤为重要。活性有机碳含量丰富的沼泽 ,甲烷主要由乙酸发酵形成 ,因此产甲烷能力较强。导致沼泽产甲烷能力异同的原因就是有效底物含量差异 ,从而使不同类型沼泽环境中产甲烷菌菌种不同 。

There exist two pathways for methane formation in mires,which are acetate fermentation and H 2/CO 2 reduction.In principle,the process of acetate fermentation driven by acetoclastic methanogens can produce much more methane than that of H 2/CO 2 reduction driven by H 2/CO 2 utilizing methanogens.In some specific environments,which one will play a more important role in bacterial methane formation depends on the content of active or labile organic carbon,especially newly fixed organic compounds such as root exudates.Mires,e.g.marsh,fen and swamp,rich in active/labile organic carbon,will produce much more methane through acetate fermentation and mires,such as bog, poor in active organic carbon,will form and emit less methane through H 2/CO 2 reduction.The reason why there exist differences in the dominant pathway and amount of methane formed in different types of mires is that the type of methanogens has changed because of changes in the concentration of acetate or H 2 and temperature and so on in mire porewater.