Insights into oxygen transport and net community production in sea ice from oxygen, nitrogen and argon concentrations

• Published in: Biogeosciences
• Main Authors: J. Zhou, B. Delille, F. Brabant, J.-L. Tison
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2014
• Subjects: Ecology; QH540-549.5; Life; QH501-531; Geology; QE1-996.5; Barrow; Sea ice; Alaska
• Online Access: https://doi.org/10.5194/bg-11-5007-2014; https://doaj.org/article/cdb2ece31c604343a5ec89e12806e993

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.