Evidence of Freezing Pressure in Sea Ice Discrete Brine Inclusions and Its Impact on Aqueous-Gaseous Equilibrium

Crabeck, O. ORCID: https://orcid.org/0000-0003-1882-9303, Galley, R. J., Mercury, L., Delille, B., Tison, J. L. and Rysgaard, S. (2019) Evidence of Freezing Pressure in Sea Ice Discrete Brine Inclusions and Its Impact on Aqueous-Gaseous Equilibrium. Journal of Geophysical Research: Oceans, 124 (3). pp. 1660-1678. ISSN 2169-9275

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Sea ice in part controls surface water properties and the ocean-atmosphere exchange of greenhouse gases at high latitudes. In sea ice, gas exists dissolved in brine and as air bubbles contained in liquid brine inclusions or as bubbles trapped directly within the ice matrix. Current research on gas dynamics within the ocean-sea ice-atmosphere interface has been based on the premise that brine with dissolved air becomes supersaturated with respect to the atmosphere during ice growth. Based on Henry's law, gas bubbles within brine should grow when brine reaches saturation during cooling, given that the total partial pressure of atmospheric gases is above the implicit pressure in brine of 1 atm. Using high-resolution light microscopy time series imagery of gas bubble evolution inside discrete brine pockets, we observed bubbles shrinking during cooling events in response to the development of freezing pressure above 3 atm. During warming of discrete brine pockets, existing bubbles expand and new bubbles nucleate in response to depressurization. Pressure variation within these inclusions has direct impacts on aqueous-gaseous equilibrium, indicating that Henry's law at a constant pressure of 1 atm is inadequate to assess the partitioning between dissolved and gaseous fractions of gas in sea ice. This new evidence of pressure build-up in discrete brine inclusions controlling the solubility of gas and nucleation of bubbles in these inclusions has the potential to affect the transport pathways of air bubbles and dissolved gases within sea ice-ocean-atmosphere interface and modifies brine biochemical properties.

Item Type: Article
Uncontrolled Keywords: brine,bubble,gas,o2, ar, n2,pressure,sea ice,geophysics,forestry,oceanography,aquatic science,ecology,water science and technology,soil science,geochemistry and petrology,earth-surface processes,atmospheric science,space and planetary science,earth and planetary sciences (miscellaneous),palaeontology,sdg 14 - life below water ,/dk/atira/pure/subjectarea/asjc/1900/1908
Faculty \ School: Faculty of Science > School of Environmental Sciences
UEA Research Groups: Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
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Depositing User: LivePure Connector
Date Deposited: 29 Mar 2019 14:30
Last Modified: 21 Oct 2022 22:33
URI: https://ueaeprints.uea.ac.uk/id/eprint/70378
DOI: 10.1029/2018JC014597

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