Changes in Circulation and Particle Scavenging in the Amerasian Basin of the Arctic Ocean over the Last Three Decades Inferred from the Water Column Distribution of Geochemical Tracers

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Grenier, Mélanie, François, Roger, Soon, Maureen, Rutgers van der Loeff, Michiel, Yu, Xiaoxin, Valk, Ole, Not, Christelle, Moran, S. Bradley, Edwards, R. Lawrence, Lu, Yanbin, Lepore, Kate, Allen, Susan
• Other Authors: Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS), University of British Columbia (UBC), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung = Alfred Wegener Institute for Polar and Marine Research = Institut Alfred-Wegener pour la recherche polaire et marine (AWI), Helmholtz-Gemeinschaft = Helmholtz Association, University of Minnesota Twin Cities (UMN), University of Minnesota System
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry; Arctic; Arctic Ocean; Climate change; Ice; permafrost; Sea ice
• Online Access: https://hal.science/hal-03805804; https://hal.science/hal-03805804/document; https://hal.science/hal-03805804/file/Grenier-etal_230Th-231Pa-eNd_Arctic-AmerasianBasin_JGR_19.pdf; https://doi.org/10.1029/2019JC015265

International audience Since the 1980-1990s, international research efforts have augmented our knowledge of the physical and chemical properties of the Arctic Ocean water masses, and recent studies have documented changes. Understanding the processes responsible for these changes is necessary to be able to forecast the local and global consequences of these property evolutions on climate. The present work investigates the distributions of geochemical tracers of particle fluxes and circulation in the Amerasian Basin and their temporal evolution over the last three decades (from stations visited between 1983 and 2015). Profiles of 230-thorium (230 Th) and 231-protactinium (231 Pa) concentrations and neodymium isotopes (expressed as ε Nd) measured in the Amerasian Basin prior to 2000 are compared to a new, post-2000s data set. The comparison shows a large scale decrease in dissolved 230 Th and 231 Pa concentrations, suggesting intensification of scavenging by particle flux, especially in coastal areas. Higher productivity and sediment resuspension from the shelves appear responsible for the concentration decrease along the margins. In the basin interior, increased lateral exchanges with the boundary circulation also contribute to the decrease in concentration. This study illustrates how dissolved 230 Th and 231 Pa, with ε Nd support, can provide unique insights not only into changes in particle flux but also into the evolution of ocean circulation and mixing. Plain Language Summary The Arctic Ocean is one of the oceanic regions most affected by climate change. The increasing summer retreat of sea ice allows greater atmosphere-ocean exchanges and light penetration, while land-ocean exchanges are expected to increase, due to enhanced continental erosion (notably through permafrost thawing and increased river flow). These changes are driven by climate and in turn impact the climate. This study aims at assessing possible shifts in oceanic circulation and particle fluxes resulting from these climate-driven changes in ...