CO2 and CH4 in sea ice from a subarctic fjord under influence of riverine input
Crabeck, O; Delille, B.; Thomas, D; Geilfus, N.-X.; Rysgaard, S; Tison, J.-L. (2014). CO2 and CH4 in sea ice from a subarctic fjord under influence of riverine input. Biogeosciences 11(23): 6525-6538. dx.doi.org/10.5194/bg-11-6525-2014 In: Gattuso, J.P.; Kesselmeier, J. (Ed.) Biogeosciences. Copernicus Publications: Göttingen. ISSN 1726-4170; e-ISSN 1726-4189, more |   |
| Authors | | Top | - Crabeck, O, more
- Delille, B., more
- Thomas, D
| - Geilfus, N.-X.
- Rysgaard, S
- Tison, J.-L., more
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| Abstract | We present the CH4 concentration [CH4], the partial 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 d18O 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 nmol L-1, which corresponds to a partial pressure ranging from 3 to 28 ppmv. This is markedly higher than the average atmospheric methane content of 1.9 ppmv. Evidently most of the trapped methane within the ice was contained inside bubbles, and only a minor portion was dissolved in the brines. The bulk ice pCO2 ranged from 60 to 330 ppmv indicating that sea ice at temperatures above -4 °C is undersaturated compared to the atmosphere (390 ppmv). This study adds to the few existing studies of CH4 and CO2 in sea ice, and we conclude that subarctic seawater can be a sink for atmospheric CO2, while being a net source of CH4. |
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