Possible influence of hydrogen concentration on microbial methane stable hydrogen isotopic composition

摘要: Factors affecting the stable hydrogen isotopic composition (δD) of important sources microbial methane to atmosphere include oxidation, methanogenic precursor (e.g., acetate vs. CO2H2), and δD environmental water. Variations in gas concentrations or rates interspecies transfer resulting from variations organic matter degradation may also affect δD-CH4. Methane produced via CO2 reduction by laboratory cultures (Balabane et al., 1987) was about 150‰ more D-depleted than shallow marine sediments CO2H2. The dissolved concentration that culture 1 mM; whereas, methane-zone typically range between 10 100 nM Conrad, 1989). relatively greater isotope fractionation appears result incorporation into protons are intracellularly hydrogenase-catalyzed oxidation gas. As rumen basal μM (Smolenski Robinson, 1988), this mechanism explain why ruminant is (Wahlen 1990) natural sedimentary environments. This process contribute wide variation δD-CH4 observed wetlands.