Summary: | We present and compare the dynamics (i.e., changes in standing stocks, saturation levels and concentrations) of O 2 , Ar and N 2 in landfast sea ice, collected in Barrow (Alaska), from February through June 2009. The comparison suggests that the dynamic of O 2 in sea ice strongly depends on physical processes (gas incorporation and subsequent transport). Since Ar and N 2 are only sensitive to the physical processes in the present study, we then discuss the use of O 2 / Ar and O 2 / N 2 to correct for the physical contribution to O 2 supersaturations, and to determine the net community production (NCP). We conclude that O 2 / Ar suits better than O 2 / N 2 , due to the relative abundance of O 2 , N 2 and Ar, and the lower biases when gas bubble formation and gas diffusion are maximized. We further estimate NCP in the impermeable layers during ice growth, which ranged from -6.6 to 3.6 µmol O 2 L -1 d -1 , and the concentrations of O 2 due to biological activity in the permeable layers during ice decay (3.8 to 122 µmol O 2 L -1 ). We finally highlight the key issues to solve for more accurate NCP estimates in the future.
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