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

Deng, Jia, McCalley, Carmody K., Frolking, Steve, Chanton, Jeff, Crill, Patrick, Varner, Ruth, Tyson, Gene, Rich, Virginia, Hines, Mark, Saleska, Scott R. and Li, Changsheng (2017) Adding stable carbon isotopes improves model representation of the role of microbial communities in peatland methane cycling. Journal of Advances in Modeling Earth Systems, 9 2: 1412-1430. doi:10.1002/2016MS000817


Author Deng, Jia
McCalley, Carmody K.
Frolking, Steve
Chanton, Jeff
Crill, Patrick
Varner, Ruth
Tyson, Gene
Rich, Virginia
Hines, Mark
Saleska, Scott R.
Li, Changsheng
Title Adding stable carbon isotopes improves model representation of the role of microbial communities in peatland methane cycling
Journal name Journal of Advances in Modeling Earth Systems   Check publisher's open access policy
ISSN 1942-2466
Publication date 2017-06-01
Year available 2017
Sub-type Article (original research)
DOI 10.1002/2016MS000817
Open Access Status File (Author Post-print)
Volume 9
Issue 2
Start page 1412
End page 1430
Total pages 19
Place of publication Hoboken, NJ United States
Publisher Wiley-Blackwell Publishing
Language eng
Abstract 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.
Formatted abstract
Climate change is expected to have significant and uncertain impacts on methane (CH4) emissions from northern peatlands. Biogeochemical models can extrapolate site-specificCH4 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 hydrogenotrophic methanogenesis (AM and HM) to CH4 production, and predicts the C isotopic signature (δ13C) 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 δ13C in emitted CH413C-CH4), a measure of the integrated effects of microbial production and consumption, and of physical transport. We also investigated the sensitivity of simulated δ13C-CH4 to C isotopic composition of substrates and, to fractionation factors for CH4 production (αAM and αHM), CH4 oxidation (αMO), and plant-mediated CH4 transport (αTP). The sensitivity analysis indicated that the δ13C-CH4 is highly sensitive to the factors associated with microbial metabolism (αAM, αHM, and αMO). 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.
Keyword Biogeochemistry
DNDC
Methane
Peatlands
Stable carbon isotope
Q-Index Code C1
Q-Index Status Provisional Code
Grant ID DE-SC0004632
1241937
1063037
2007-4547
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: HERDC Pre-Audit
Australian Centre for Ecogenomics
 
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