CO2 and CH4 in sea ice from a subarctic fjord under influence of riverine input

Crabeck, O. and Delille, B. and Thomas, D. and Geilfus, N.-X. and Rysgaard, S. and Tilson, J.-L. (2014) CO2 and CH4 in sea ice from a subarctic fjord under influence of riverine input. Biogeosciences, 11 (23). pp. 66525-6538. DOI: 10.5194/bg-11-6525-2014

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We present the CH4 concentration [CH4], the par- tial pressure of CO2 (pCO2) and the total gas content in bulk sea ice from subarctic, land-fast sea ice in the Kapisillit fjord, Greenland. Fjord systems are characterized by freshwater runoff and riverine input and based on $\delta$18O data, we show that >30\% of the surface water originated from periodic river input during ice growth. This resulted in fresher sea-ice layers with higher gas content than is typical from marine sea ice. The bulk ice [CH4] ranged from 1.8 to 12.1 nmolL�1, which corresponds to a partial pressure ranging from 3 to 28ppmv. This is markedly higher than the average atmo- spheric methane content of 1.9ppmv. Evidently most of the trapped methane within the icewas contained inside bubbles, and only a minor portion was dissolved in the brines. The bulk ice pCO2 ranged from 60 to 330ppmv indicating that sea ice at temperatures above �4 �C is undersaturated com- pared to the atmosphere (390 ppmv). This study adds to the few existing studies of CH4 and CO2 in sea ice, and we con- clude that subarctic seawater can be a sink for atmospheric CO2, while being a net source of CH4.

Item Type: Article
Subjects: Research Publications
Departments: College of Natural Sciences > School of Ocean Sciences
Date Deposited: 24 Jul 2015 02:14
Last Modified: 23 Sep 2015 02:51
ISSN: 1726-4170
URI: http://e.bangor.ac.uk/id/eprint/4850
Identification Number: DOI: 10.5194/bg-11-6525-2014
Publisher: European Geosciences Union (EGU)
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