Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 7, issue 11
Biogeosciences, 7, 3893-3900, 2010
https://doi.org/10.5194/bg-7-3893-2010
© Author(s) 2010. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 7, 3893-3900, 2010
https://doi.org/10.5194/bg-7-3893-2010
© Author(s) 2010. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 29 Nov 2010

Research article | 29 Nov 2010

Stable carbon isotope fractionation during methanogenesis in three boreal peatland ecosystems

P. E. Galand1,2, K. Yrjälä3, and R. Conrad4 P. E. Galand et al.
  • 1UPMC Univ Paris 06, Observatoire Océanologique, 66651 Banyuls-sur-Mer, France
  • 2CNRS, FRE 3350, Laboratoire d'écogéochimie des environnements benthiques (LECOB), Observatoire Océanologique, 66650 Banyuls-sur-Mer, France
  • 3Dept. of Biological and Environmental Sciences, General Microbiology, University of Helsinki, 00014 Helsinki, Finland
  • 4Max-Planck-Institute for Terrestrial Microbiology, Karl-von-Frisch-Str.10, 35043 Marburg, Germany

Abstract. The degradation of organic matter to CH4 and CO2 was investigated in three different boreal peatland systems in Finland, a mesotrophic fen (MES), an oligotrophic fen (OLI), and an ombrotrophic peat (OMB). MES had similar production rates of CO2 and CH4, but the two nutrient-poor peatlands (OLI and OMB) produced in general more CO2 than CH4. δ13C analysis of CH4 and CO2 in the presence and absence methyl fluoride (CH3F), an inhibitor of acetoclastic methanogenesis, showed that CH4 was predominantly produced by hydrogenotrophic methanogenesis and that acetoclastic methanogenesis only played an important role in MES. These results, together with our observations concerning the collective inhibition of CH4 and CO2 production rates by CH3F, indicate that organic matter was degraded through different paths in the mesotrophic and the nutrient-poor peatlands. In the mesotrophic fen, the major process is canonical fermentation followed by acetoclastic and hydrogenotrophic methanogenesis, while in the nutrient-poor peat, organic matter was apparently degraded to a large extent by a different path which finally involved hydrogenotrophic methanogenesis. Our data suggest that degradation of organic substances in the oligotrophic environments was incomplete and involved the use of organic compounds as oxidants.

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