Modeling methane emissions from arctic lakes: Model development and site‐level study

Journal of Advances in Modeling Earth Systems

Zeli Tan¹  Qianlai Zhuang¹ 

[1] Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, Indiana, USA

关键词: methane emissions;    arctic lake;    yedoma lake;    thermokarst lake;   

DOI  :  10.1002/2014MS000344

来源: Wiley

【 摘 要 】

Abstract

To date, methane emissions from lakes in the pan-arctic region are poorly quantified. In order to investigate the response of methane emissions from this region to global warming, a process-based climate-sensitive lake biogeochemical model was developed. The processes of methane production, oxidation, and transport were modeled within a one-dimensional sediment and water column. The sizes of ¹⁴C-enriched and ¹⁴C-depleted carbon pools were explicitly parameterized. The model was validated using observational data from five lakes located in Siberia and Alaska, representing a large variety of environmental conditions in the arctic. The model simulations agreed well with the measured water temperature and dissolved CH₄ concentration (mean error less than 1°C and 0.2 μM, respectively). The modeled CH₄ fluxes were consistent with observations in these lakes. We found that bubbling-rate-controlling nitrogen (N₂) stripping was the most important factor in determining CH₄ fraction in bubbles. Lake depth and ice cover thickness in shallow waters were also controlling factors. This study demonstrated that the thawing of Pleistocene-aged organic-rich yedoma can fuel sediment methanogenesis by supplying a large quantity of labile organic carbon. Observations and modeling results both confirmed that methane emission rate at thermokarst margins of yedoma lakes was much larger (up to 538 mg CH₄ m⁻² d⁻¹) than that at nonthermokarst zones in the same lakes and a nonyedoma, nonthermokarst lake (less than 42 mg CH₄ m⁻² d⁻¹). The seasonal variability of methane emissions can be explained primarily by energy input and organic carbon availability.

【 授权许可】

CC BY-NC-ND   
© 2015. The Authors.

Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.