Temperature limitation of hydrogen turnover and methanogenesis in anoxic paddy soil

Abstract

The shift of incubation temperature in anoxic paddy soil from 30°C to 15°C resulted in a reversible decrease of the methane production rate and of the H2 steady state partial pressure. Only at 30°C but not at 17°C, total CH4 production rates were enhanced by the addition of H2, acetate, or cellulose compared to the control. Apparent activation energies which were calculated from the temperature dependence of CH4 production were higher in presence than in absence of excess H2. Decrease of temperature caused a decrease of the H2 turnover rate constant and of the Gibbs free energy of H2‐dependent methanogenesis, and also resulted in a smaller contribution of H2 to total methanogenesis. However, H2‐dependent methanogenesis was significantly stimulated by excess H2 and slightly inhibited by acetate at low as well as high temperature. The results show that H2‐producing bacteria were limited by temperature to a greater extent than the methanogens so that the methanogenic microbial community in paddy soil was limited by the supply of H2. At low as well as high temperatures, excess H2 apparently enabled part of the methanogenic community to shift from acetate‐dependent to H2‐dependent CH4 production. At low temperature, excess H2 had only this effect, but with increasing temperature, excess H2 additionally stimulated total methanogenic activity and eventually even growth.

Water level, vegetation composition, and plant productivity explain greenhouse gas fluxes in temperate cutover fens after inundation

“…The temperature dependency of methane production and emission was previously described by the Arrhenius function or its logarithmic form (Conrad et al, 1987;Schütz et al, 1990;Daulat and Clymo, 1998;Kim et al, 1998):…”

Combination of photoacoustic detector with gas diffusion probes for the measurement of methane concentration gradients in submerged paddy soil

“…Microcosms of rice paddy soil were prepared from air-dried soil sampled in rice fields at the Italian Rice Research Institute in Vercelli in 1991 (Conrad et al, 1987). The soil properties were described earlier (Schtitz et al, 1989).…”

Effect of Temperature on Carbon and Electron Flow and on the Archaeal Community in Methanogenic Rice Field Soil

“…Most studies indeed have found a slightly higher contribution of acetate, suggesting that homoacetogenesis is involved in the fermentation of the saccharides (12,51,73). It is also assumed that the fraction of hydrogenotrophic methanogenesis decreases at low temperature, as the pathway of carbon and electron flow changes, when the temperature of the rice field soil (4,16,18), as well as of the lake sediment (56,57), is shifted. Several authors demonstrated the existence of psychrotolerant homoacetogens which compete with methanogens for H 2 at low temperatures (17,33,34,45).…”

“…From these factors temperature is recognized as one of the most important (31, 53, 58). Temperature not only has an effect on the methane production itself but also has an effect on the decomposition of organic materials from which the methanogenic substrates are produced (4,16,32,58,68).…”

“…From these factors temperature is recognized as one of the most important (31, 53, 58). Temperature not only has an effect on the methane production itself but also has an effect on the decomposition of organic materials from which the methanogenic substrates are produced (4,16,32,58,68).The most important precursors of CH 4 in anoxic rice field soil are acetate and H 2 /CO 2 , which theoretically contribute Ͼ67 and Ͻ33%, respectively, when polysaccharides are anaerobically degraded (11). Most studies indeed have found a slightly higher contribution of acetate, suggesting that homoacetogenesis is involved in the fermentation of the saccharides (12,51,73).…”