Carbonate system evolution at the Arctic Ocean surface during autumn freeze-up

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Abstract

[1] Based on comprehensive measurements of carbonate system parameters in sea ice, brines, and surface waters across a variety of ice types in the eastern Beaufort Sea during November and December of 2007, the newly forming sea ice appeared to release CO2. Not only was pCO2 high within the ice, but high salinities and inorganic carbon concentrations in the surface waters directly below the ice and in frost flowers above the ice indicated that brines and CO2 were moving out of the ice as it was forming. In addition, relative to salinity, the ice was generally enriched in alkalinity but depleted in total inorganic carbon. These observations support the hypothesis that as sea ice forms, increasing brine concentrations and CaCO3 precipitation release CO2. However, based on this data set, we are unable to quantify the relative importance of release to the atmosphere versus to the underlying waters. In addition, a comparison of three different methods for determining pCO2 in sea ice highlights a critical need for additional methodological development.

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