Sea Ice CO 2 Dynamics Across Seasons: Impact of Processes at the Interfaces

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: van Der Linden, F., Tison, Jean-Louis, Champenois, W., Moreau, S., Carnat, Gautiher, Kotovitch, M., Fripiat, François, Deman, F., Roukaerts, A., Dehairs, Frank, Wauthy, S., Lourenço, Antonio, Vivier, Frédéric, Haskell, T., Delille, Bruno
• Other Authors: Unité d'Océanographie Chimique, Interfacultary Center for Marine Research (MARE), Université de Liège-Université de Liège, Laboratoire de Glaciologie Bruxelles, Université libre de Bruxelles (ULB), Norwegian Polar Institute, Vrije Universiteit Brussel (VUB), Développement Instrumental et Techniques Marines (DITM), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Processus et interactions de fine échelle océanique (PROTEO), Callaghan Innovation, Antarctica New Zealand, Belgian Science Policy, Fonds De La Recherche Scientifique ‐ FNRS
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2020
• Subjects: Antarctica; air‐sea ice fluxes; carbon dioxide; sea ice; trophic status; biofilm; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Antarc*; McMurdo Sound; Sea ice
• Online Access: https://hal.science/hal-03035303; https://hal.science/hal-03035303/document; https://hal.science/hal-03035303/file/JGR%20Oceans%20-%202020%20-%20Van%20der%20Linden%20-%20Sea%20Ice%20CO2%20Dynamics%20Across%20Seasons%20Impact%20of%20Processes%20at%20the%20Interfaces.pdf; https://doi.org/10.1029/2019jc015807

International audience Winter to summer CO 2 dynamics within landfast sea ice in McMurdo Sound (Antarctica) were investigated using bulk ice pCO 2 measurements, air‐snow‐ice CO 2 fluxes, dissolved inorganic carbon (DIC), total alkalinity (TA), and ikaite saturation state. Our results suggest depth‐dependent biotic and abiotic controls that led us to discriminate the ice column in three layers. At the surface, winter pCO 2 supersaturation drove CO 2 release to the atmosphere while spring‐summer pCO 2 undersaturation led to CO 2 uptake most of the time. CO 2 fluxes showed a diel pattern superimposed upon this seasonal pattern which was potentially assigned to either ice skin freeze‐thaw cycles or diel changes in net community production. In the ice interior, the pCO 2 decrease across the season was driven by physical processes, mainly independent of the autotrophic and heterotrophic phases. Bottom sea ice was characterized by a massive biomass build‐up counterintuitively associated with transient heterotrophic activity and nitrate plus nitrite accumulation. This inconsistency is likely related to the formation of a biofilm. This biofilm hosts both autotrophic and heterotrophic activities at the bottom of the ice during spring and may promote calcium carbonate precipitation.