Modeling methane emissions from arctic lakes: Model development and site‐level study. (11th April 2015)

• Record Type: Journal Article
• Authors: Tan, Zeli; Zhuang, Qianlai; Walter Anthony, Katey
• Is Part Of: Journal of advances in modeling earth systems. Volume 7:Number 2(2015:Jun.)
• Page Start: 459
• Page End: 483
• Publication Date: 2015-04-11
• Subjects: Geological modeling -- Periodicals; Climatology -- Periodicals; Geochemical modeling -- Periodicals; 551.5011
• DOI: 10.1002/2014MS000344
• Languages: English
• ISSNs: 1942-2466

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>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 <sup>14</sup>C‐enriched and <sup>14</sup>C‐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 CH<sub>4</sub> concentration (mean error less than 1°C and 0.2 μM, respectively). The modeled CH<sub>4</sub> fluxes were consistent with observations in these lakes. We found that bubbling‐rate‐controlling nitrogen (N<sub>2</sub>) stripping was the most important factor in determining CH<sub>4</sub> 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 CH<sub>4</sub> m<sup>−2</sup> d<sup>−1</sup>) than that at nonthermokarst zones in the same lakes and a nonyedoma, nonthermokarst lake (less than 42 mg CH<sub>4</sub> m<sup>−2</sup> d<sup>−1</sup>). The seasonal variability of methane emissions can be explained primarily by energy input and organic carbon availability.</p> </abstract>