Conrad R., Claus P., Chidthaisong A., Lu Y., Scavino A. F., Liu Y., Angel R., Galand P. E., Casper P., Guérin Frédéric, Enrich-Prast A. (2014). Stable carbon isotope biogeochemistry of propionate and acetate in methanogenic soils and lake sediments. Organic Geochemistry, 73, p. 1-7. ISSN 0146-6380.
Titre du document
Stable carbon isotope biogeochemistry of propionate and acetate in methanogenic soils and lake sediments
Année de publication
2014
Auteurs
Conrad R., Claus P., Chidthaisong A., Lu Y., Scavino A. F., Liu Y., Angel R., Galand P. E., Casper P., Guérin Frédéric, Enrich-Prast A.
Source
Organic Geochemistry, 2014,
73, p. 1-7 ISSN 0146-6380
In anoxic environments, degradation of organic matter (OM) results in strong fractionation of carbon isotopes, with formation of C-13-depleted CH4. Propionate and acetate are important products of OM fermentation. Propionate is further fermented to acetate. Acetate is a direct precursor of CH4, the remainder usually being produced from H-2-mediated CO2 reduction. There is a paucity of data for the turnover of acetate and, even more so, propionate. We therefore analyzed the d 13C values of organic carbon, propionate, acetate and the methyl (Me) group of acetate (acetate-Me) during the production of CH4 in anoxic incubations of various flooded and non-flooded soils and various lake sediments. Incubation in the presence of CH3F, which inhibits CH4 production from acetate, allowed exclusion of isotope effects during aceticlastic methanogenesis. Despite the variation inherent in the wide diversity of sample type and origin, the data collectively showed that the d C-13 value of acetate was only marginally different (-2 +/- 5%) from that of OM, while propionate was depleted in C-13 relative to total acetate (-6 +/- 5 parts per thousand). Acetate-Me was generally depleted in C-13 relative to total acetate (- 8 +/- 5%). Thus, isotopic enrichment factors during the degradation of OM to total propionate and acetate were much smaller than those during hydrogenotrophic and aceticlastic methanogenesis or the intramolecular difference in d 13C between the carboxyl (CO2H) and Me of acetate, so that the d C-13 value of OM may be used as a proxy when data for acetate are not available.
Plan de classement
Sciences du milieu [021]
;
Hydrologie [062]
;
Géologie et formations superficielles [064]
Description Géographique
BRESIL ; THAILANDE ; CAMEROUN ; ZONE TROPICALE ; ALLEMAGNE ; CHINE ; URUGUAY ; ZONE TEMPEREE ; ETATS UNIS ; ISRAEL ; AUSTRALIE ; ZONE ARIDE ; ZONE SEMIARIDE ; TIBET ; ZONE D'ALTITUDE ; FINLANDE
Localisation
Fonds IRD [F B010062357]
Identifiant IRD
fdi:010062357