Carbon monoxide consumption and production by wetland peats

Abstract

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 Wmol cm 3Q ), and acetate (10 mM) had no effect on CO consumption. Formate and glucose (10 mM) temporarily stimulated net CO and H P 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 (V mxp ) in each sediment were similar, 1^2 nmol CO cm 3Q sediment h 3I , with apparent half saturation constants (K pp ) 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. z

Occurrence of Carbon Monoxide during Organic Waste Degradation

“…18 CO is both consumed and produced by methanogenic, acetogenic, and sulfate-reducing bacteria, with transient pulses of CO formed in anaerobic reactors after organic C loading. 18 It was speculated that CO was formed abiotically from substrates such as porphyrin, polyphenols, aromatic acids, and methionine precursors. 18 Cell suspensions of acetate-grown methanogenic bacteria produce CO concentrations up to 15,000 ppm, in contrast to the estimated chemical equilibrium concentration of 100 ppm.…”

“…18 It was speculated that CO was formed abiotically from substrates such as porphyrin, polyphenols, aromatic acids, and methionine precursors. 18 Cell suspensions of acetate-grown methanogenic bacteria produce CO concentrations up to 15,000 ppm, in contrast to the estimated chemical equilibrium concentration of 100 ppm. 19 The CO production was coupled to the exergonic formation of CH 4 from CO 2 and H 2 .…”

“…The experiments support the theory of methanogens being the producers of CO in the aerobic experiments during intermittent oxygen loading, as stated by others. 18,19 Field Scale. The two locations with windrow composting that were surveyed represent grab samples from different seasons and with a different number of measurements and are, thus, meant for illustration.…”

Anaerobic Metabolism: Linkages to Trace Gases and Aerobic Processes

“…Carbon monoxide is converted to CH 4 , but the physiological role this substrate plays is uncertain (Vogels et ah, 1988). Rich and King (1999) measured maximum potential uptake velocities of 1-2 nmol CO cm -3 sediment h _1 in anaerobic soils, but the response to amendments of S0 4 ", Fe(III), and the methanogen inhibitor bromoethanesulfonic acid (BES), suggested that no more than 30% of the oxidation activity was due to methanogens. Methanogens degrade chlorinated pollutants and have been used for bioremediation (Fathepure and Boyd, 1988;Mikesell and Boyd, 1990).…”

Hydrologic Significance of Carbon Monoxide Concentrations in Ground Water

“…Rich and King (1999) showed that a pattern of CO production and subsequent consumption was observed when vials containing wetland peat were amended with oxygen. To a lesser extent, this effect was observed with other electron acceptors such as nitrate and sulfate.…”