Carbon monoxide consumption and production by wetland peats

Wetland peats were analyzed for their potential to consume and produce carbon monoxide (CO) under aerobic and anaerobic conditions. Kinetic and functional characteristics of anaerobic CO consumption were compared with those of methanogenesis. Inhibitors of methanogenesis and sulfate reduction decreased the rate of CO consumption by 30 and 20%, respectively, suggesting that methanogens and sulfate reducers played secondary roles in CO uptake. Low concentrations of nitrate (0.2 mM) stimulated CO uptake, while high concentrations (20 mM) were partially inhibitory. Sulfate (20 mM), ferric iron (60 μmol cm−3), and acetate (10 mM) had no effect on CO consumption. Formate and glucose (10 mM) temporarily stimulated net CO and H2 production. Aerobic incubations of previously anaerobic peat stimulated transient CO production. Kinetic analysis of anaerobic CO consumption by two sediment types (organic peat and mineral silt) showed that maximum potential uptake velocities (Vmaxp) in each sediment were similar, 1–2 nmol CO cm−3 sediment h−1, with apparent half saturation constants (Kapp) ranging from 5 to 37 nM CO. Anaerobic CO consumption may limit CO accumulation in wetland peats and sediments, thereby affecting CO emissions. Understanding the role and characteristics of wetland CO consumption may help explain current and future patterns in wetland CO dynamics.