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Title: Adding stable carbon isotopes improves model representation of the role of microbial communities in peatland methane cycling

Climate change is expected to have significant and uncertain impacts on methane (CH 4) emissions from northern peatlands. Biogeochemical models can extrapolate site-specific CH 4 measurements to larger scales and predict responses of CH 4 emissions to environmental changes. However, these models include considerable uncertainties and limitations in representing CH4 production, consumption, and transport processes. To improve predictions of CH 4 transformations, we incorporated acetate and stable carbon (C) isotopic dynamics associated with CH 4 cycling into a biogeochemistry model, DNDC. By including these new features, DNDC explicitly simulates acetate dynamics and the relative contribution of acetotrophic and hydrogenotrophic methanogenesis (AM and HM) to CH 4 production, and predicts the C isotopic signature (δ 13C) in soil C pools and emitted gases. When tested against biogeochemical and microbial community observations at two sites in a zone of thawing permafrost in a subarctic peatland in Sweden, the new formulation substantially improved agreement with CH 4 production pathways and δ 13C in emitted CH 413C-CH 4), a measure of the integrated effects of microbial production and consumption, and of physical transport. We also investigated the sensitivity of simulated δ 13C-CH 4 to C isotopic composition of substrates and, to fractionationmore » factors for CH4 production (α AM and α HM), CH 4 oxidation (α MO), and plant-mediated CH 4 transport (α TP). The sensitivity analysis indicated that the δ13C-CH 4 is highly sensitive to the factors associated with microbial metabolism (α AM, α HM, and α MO). The model framework simulating stable C isotopic dynamics provides a robust basis for better constraining and testing microbial mechanisms in predicting CH 4 cycling in peatlands.« less
ORCiD logo [1] ; ORCiD logo [2] ;  [1] ; ORCiD logo [3] ; ORCiD logo [4] ; ORCiD logo [5] ;  [6] ; ORCiD logo [7] ;  [8] ;  [9] ;  [1]
  1. Univ. of New Hampshire, Durham, NH (United States). Earth Systems Research Center, Institute for the Study of Earth, Oceans and Space
  2. Rochester Institute of Technology, NY (United States). Thomas H. Gosnell School of Life Sciences
  3. Florida State Univ., Tallahassee, FL (United States). Dept. of Earth, Ocean and Atmospheric Science
  4. Department of Geological Sciences, Stockholm University, Stockholm Sweden
  5. Univ. of New Hampshire, Durham, NH (United States). Earth Systems Research Center, Institute for the Study of Earth, Oceans and Space; Univ. of New Hampshire, Durham, NH (United States). Dept. of Earth Sciences
  6. Univ. of Queensland, Brisbane (Australia). Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences
  7. The Ohio State Univ., Columbus, OH (United States). Dept of Microbiology
  8. Univ. of Massachusetts, Lowell, MA (United States). Dept. of Biological Sciences
  9. Univ. of Arizona, Tucson, AZ (United States). Dept. of Ecology and Evolutionary Biology
Publication Date:
Grant/Contract Number:
SC0004632; SC0010580
Published Article
Journal Name:
Journal of Advances in Modeling Earth Systems
Additional Journal Information:
Journal Volume: 9; Journal Issue: 2; Journal ID: ISSN 1942-2466
American Geophysical Union (AGU)
Research Org:
Univ. of Arizona, Tucson, AZ (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1363820; OSTI ID: 1393576