Climate change is expected to have significant and uncertain impacts on methane (CH4) emissions from northern peatlands. Biogeochemical models can extrapolate site-specificCH(4) measurements to larger scales and predict responses of CH4 emissions to environmental changes. However, these models include considerable uncertainties and limitations in representing CH4 production, consumption, and transport processes. To improve predictions of CH4 transformations, we incorporated acetate and stable carbon (C) isotopic dynamics associated with CH4 cycling into a biogeochemistry model, DNDC. By including these new features, DNDC explicitly simulates acetate dynamics and the relative contribution of acetotrophic and hydro-genotrophic methanogenesis (AM and HM) to CH4 production, and predicts the C isotopic signature (delta C-13) 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 CH4 production pathways and delta C-13 in emitted CH4 (delta C-13-CH4), a measure of the integrated effects of microbial production and consumption, and of physical transport. We also investigated the sensitivity of simulated delta C-13-CH4 to C isotopic composition of substrates and, to fractionation factors for CH4 production (alpha(AM) and alpha(HM)), CH4 oxidation (alpha(MO)), and plant-mediated CH4 transport (alpha(TP)). The sensitivity analysis indicated that the delta C-13-CH4 is highly sensitive to the factors associated with microbial metabolism (alpha(AM), alpha(HM), and alpha(MO)). The model framework simulating stable C isotopic dynamics provides a robust basis for better constraining and testing microbial mechanisms in predicting CH4 cycling in peatlands.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/625198 |
| Date | 06 1900 |
| Creators | Deng, Jia, McCalley, Carmody K, Frolking, Steve, Chanton, Jeff, Crill, Patrick, Varner, Ruth, Tyson, Gene, Rich, Virginia, Hines, Mark, Saleska, Scott R., Li, Changsheng |
| Contributors | Univ Arizona, Dept Ecol & Evolutionary Biol, Earth Systems Research Center, Institute for the Study of Earth, Oceans and Space, University of New Hampshire; Durham New Hampshire USA, Thomas H. Gosnell School of Life Sciences, Rochester Institute of Technology, One Lomb Memorial Drive; Rochester New York USA, Earth Systems Research Center, Institute for the Study of Earth, Oceans and Space, University of New Hampshire; Durham New Hampshire USA, Department of Earth, Ocean and Atmospheric Science; Florida State University; Tallahassee Florida USA, Department of Geological Sciences; Stockholm University; Stockholm Sweden, Earth Systems Research Center, Institute for the Study of Earth, Oceans and Space, University of New Hampshire; Durham New Hampshire USA, Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences; University of Queensland; Brisbane Queensland Australia, Department of Microbiology; The Ohio State University; Columbus Ohio USA, Department of Biological Sciences; University of Massachusetts Lowell; Lowell Massachusetts USA, Department of Ecology and Evolutionary Biology; University of Arizona; Tucson Arizona USA, Earth Systems Research Center, Institute for the Study of Earth, Oceans and Space, University of New Hampshire; Durham New Hampshire USA |
| Publisher | AMER GEOPHYSICAL UNION |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | Article |
| Rights | © 2017. The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License. |
| Relation | http://doi.wiley.com/10.1002/2016MS000817 |
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