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| Titel |
Physical controls on the storage of methane in landfast sea ice |
| VerfasserIn |
J. Zhou, J.-L. Tison, G. Carnat, N.-X. Geilfus, B. Delille |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1994-0416
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| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 8, no. 3 ; Nr. 8, no. 3 (2014-06-03), S.1019-1029 |
| Datensatznummer |
250116163
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| Publikation (Nr.) |
 copernicus.org/tc-8-1019-2014.pdf |
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| Zusammenfassung |
| We report on methane (CH4) dynamics in landfast sea ice, brine and
under-ice seawater at Barrow in 2009. The CH4 concentrations in
under-ice water ranged from 25.9 to 116.4 nmol L−1sw,
indicating a supersaturation of 700 to 3100% relative to the atmosphere.
In comparison, the CH4 concentrations in sea ice ranged from 3.4 to
17.2 nmol L−1ice and the deduced CH4 concentrations in
brine from 13.2 to 677.7 nmol L−1brine. We investigated the processes underlying the difference in CH4 concentrations between
sea ice, brine and under-ice water and suggest that biological controls
on the storage of CH4 in ice were minor in comparison to the physical
controls. Two physical processes regulated the storage of CH4 in our
landfast ice samples: bubble formation within the ice and sea ice
permeability. Gas bubble formation due to brine concentration and solubility decrease favoured the
accumulation of CH4 in the ice at the beginning of ice growth. CH4
retention in sea ice was then twice as efficient as that of salt; this also
explains the overall higher CH4 concentrations in brine than in the
under-ice water. As sea ice thickened, gas bubble formation became less
efficient, CH4 was then mainly trapped in the dissolved state. The
increase of sea ice permeability during ice melt marked the end of CH4
storage. |
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