Spatial distribution of microbial methane production pathways in temperate zone wetland soils: Stable carbon and hydrogen isotope evidence

摘要: The identity and distribution of substrates that support CH4 production in wetlands is poorly known at present. Organic compounds are the primary methanogenic precursor all depths within anoxic wetland soils; however, microbial processes by which these ultimately converted to uncertain. Based on stable isotope measurements ΣCO2 extracted from soil porewaters two temperate zone wetlands, we present evidence a systematic spatial pathways can exist certain anoxic, organic-rich soils. acetate fermentation pathway favored shallow subsurface, while methanogenesis reduction CO2 with H2 becomes more predominant older, less reactive peat depth. This account for many reported emission characteristics particular, their sensitivity changes productivity, temperature, hydrology. These factors play an important role controlling short-term supply labile fermentive methanogens subsurface where most intense occurs. Predominance CO2-reduction depth may help explain reports semifossil age lower layers.