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Title: Modeling the impediment of methane ebullition bubbles by seasonal lake ice

Microbial methane (CH 4) ebullition (bubbling) from anoxic lake sediments comprises a globally significant flux to the atmosphere, but ebullition bubbles in temperate and polar lakes can be trapped by winter ice cover and later released during spring thaw. This "ice-bubble storage" (IBS) constitutes a novel mode of CH 4 emission. Before bubbles are encapsulated by downward-growing ice, some of their CH 4 dissolves into the lake water, where it may be subject to oxidation. We present field characterization and a model of the annual CH 4 cycle in Goldstream Lake, a thermokarst (thaw) lake in interior Alaska. We find that summertime ebullition dominates annual CH 4 emissions to the atmosphere. Eighty percent of CH 4 in bubbles trapped by ice dissolves into the lake water column in winter, and about half of that is oxidized. The ice growth rate and the magnitude of the CH 4 ebullition flux are important controlling factors of bubble dissolution. Seven percent of annual ebullition CH 4 is trapped as IBS and later emitted as ice melts. In a future warmer climate, there will likely be less seasonal ice cover, less IBS, less CH 4 dissolution from trapped bubbles, and greater CH 4 emissionsmore » from northern lakes.« less
Authors:
; ; ; ;
Publication Date:
Grant/Contract Number:
#DE-NT0005665
Type:
Published Article
Journal Name:
Biogeosciences (Online)
Additional Journal Information:
Journal Name: Biogeosciences (Online); Journal Volume: 11; Journal Issue: 23; Journal ID: ISSN 1726-4189
Publisher:
European Geosciences Union
Sponsoring Org:
USDOE
Country of Publication:
Germany
Language:
English
OSTI Identifier:
1197863