%0 Journal Article
%9 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES
%A Conrad, R.
%A Claus, P.
%A Chidthaisong, A.
%A Lu, Y.
%A Scavino, A. F.
%A Liu, Y.
%A Angel, R.
%A Galand, P. E.
%A Casper, P.
%A Guérin, Frédéric
%A Enrich-Prast, A.
%T Stable carbon isotope biogeochemistry of propionate and acetate in methanogenic soils and lake sediments
%D 2014
%L fdi:010062357
%G ENG
%J Organic Geochemistry
%@ 0146-6380
%K Acetate ; Propionate ; Methane ; Organic matter ; Fermentation ; Isotope fractionation ; Anoxic soil ; Lake sediment
%K BRESIL ; THAILANDE ; CAMEROUN ; ZONE TROPICALE ; ALLEMAGNE ; CHINE ; URUGUAY ; ZONE TEMPEREE ; ETATS UNIS ; ISRAEL ; AUSTRALIE ; ZONE ARIDE ; ZONE SEMIARIDE ; TIBET ; ZONE D'ALTITUDE ; FINLANDE
%M ISI:000338967500001
%P 1-7
%R 10.1016/j.orggeochem.2014.03.010
%U https://www.documentation.ird.fr/hor/fdi:010062357
%> https://www.documentation.ird.fr/intranet/publi/2014/08/010062357.pdf
%V 73
%W Horizon (IRD)
%X 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.
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