Biogeochemical River Runoff Drives Intense Coastal Arctic Ocean CO2 Outgassing

• Published in: Geophysical Research Letters
• Main Authors: Bertin, C., Carroll, D., Menemenlis, D., Dutkiewicz, S., Zhang, H., Matsuoka, A., Tank, S., Manizza, M., Miller, C, E, Babin, M., Mangin, A., Le Fouest, V.
• Other Authors: LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Moss Landing Marine Laboratories, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Massachusetts Institute of Technology (MIT), Institute for the Study of Earth, Oceans, and Space Durham (EOS), University of New Hampshire (UNH), University of Alberta, Scripps Institution of Oceanography (SIO - UC San Diego), University of California San Diego (UC San Diego), University of California (UC)-University of California (UC), Takuvik Joint International Laboratory ULAVAL-CNRS, Université Laval Québec (ULaval)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), This work is part of the Nunataryuk project; the project has received funding under the European Union's Horizon 2020 Research and Innovation Programme under grant agreement no. 773421. This work was also funded by the Centre National de la Recherche Scientifique (CNRS, LEFE program). Part of this research was supported by Japan Aerospace Exploration Agency (JAXA) Global Change Observation Mission-Climate (GCOM-C) to AM (contract #19RT000542). This work was also supported by the NASA Earth Science Division's Interdisciplinary Science (IDS) program through an award to the Jet Propulsion Laboratory, California Institute of Technology, under contract with National Aeronautics and Space Administration (80NM0018D0004). Part of this research was supported by the Arctic Great River Observatory (ArcticGRO) to ST (contract NSF 1913888)., European Project: 773421,H2020,H2020-BG-2017-1,NUNATARYUK(2017)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry; Arctic; Arctic Ocean; Mackenzie River; Beaufort Sea; Mackenzie river
• Online Access: https://hal.science/hal-04074930; https://hal.science/hal-04074930/document; https://hal.science/hal-04074930/file/Bertin%20et%20al.%20-%202023%20-%20Biogeochemical%20River%20Runoff%20Drives%20Intense%20Coastal.pdf; https://doi.org/10.1029/2022GL102377

International audience Arctic warming alters land-to-sea fluxes of nutrients and organic matter, which impact air-sea carbon exchange. Here we use an ocean-biogeochemical model of the southeastern Beaufort Sea (SBS) to investigate the role of Mackenzie River biogeochemical discharge in modulating air-sea CO2 fluxes during 2000–2019. The contribution of six biogeochemical discharge constituents leads to a net CO2 outgassing of 0.13 TgC yr −1, with a decrease in the coastal SBS carbon sink of 0.23 and 0.4 TgC yr −1 due to riverine dissolved organic and inorganic carbon, respectively. Years with high (low) discharge promote more CO2 outgassing (uptake) from the river plume. These results demonstrate that the Mackenzie River modulates the capacity of the SBS to act as a sink or source of atmospheric CO2. Our work suggests that accurate model representation of land-to-sea biogeochemical coupling can be critical for assessing present-day Arctic coastal ocean response to the rapidly changing environment.