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

Melanie Grenier, Roger François, Maureen Soon, Michiel Rutgers van der Loeff, Xiaoxin Yu, Ole Valk, Christelle Not, S. Bradley Moran, R. Lawrence Edwards, Yanbin Lu, Kate Lepore, Susan E. Allen

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

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 (230Th) and 231-protactinium (231Pa) concentrations and neodymium isotopes (expressed as εNd) 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 230Th and 231Pa 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 230Th and 231Pa, with εNd support, can provide unique insights not only into changes in particle flux but also into the evolution of ocean circulation and mixing.

Original languageEnglish (US)
Pages (from-to)9338-9363
Number of pages26
JournalJournal of Geophysical Research: Oceans
Volume124
Issue number12
DOIs
StatePublished - Dec 1 2019

Bibliographical note

Funding Information:
We wish to acknowledge the assistance of the officers and crew of the USCG , the CCGS , , , and the R/V during the research expeditions. Jay Cullen, Philippe Tortell, and Kristina Brown are also acknowledged for their implication in the scientific managing of the 2015 cruise. We are grateful to Pascal Guillot, Thomas Linkowski, and Cris Seaton (Quebec‐Ocean and ArcticNet) for their technical support at sea. We thank Cheng Kuang for her great help during the cruise preparation and on‐board and Isabelle Baconnais for sampling at sea. We also acknowledge, on the one hand, Vivian Lai and Dominique Weis (Pacific Centre for Isotopic and Geochemical Research, EOAS) and, on the other hand, Stephanie Mounic and Mathieu Benoit (Centre National de la Recherche Scientifique, GET) for their technical support on the ICP‐MS and on the TIMS, respectively. Finally, we thank the two anonymous reviewers whose insightful comments and suggestions helped to improve the manuscript. The Canadian Arctic GEOTRACES project was funded by the Canadian research program NSERC CCAR. M. Grenier was supported by a European Union's Horizon 2020 research and innovation programme (Marie Skłodowska‐Curie action, Grant Agreement 657853). Christelle Not was supported by Natural Sciences and Engineering Research Council of Canada research funds awarded to Claude Hillaire‐Marcel and the Fonds Québécois de la Recherche sur la Nature et les Technologies from GEOTOP. The data set reported in the tables is available on the GEOTRACES International Data Assembly Centre ( www.bodc.ac.uk/geotraces/data/ ). Healy Sir Wilfrid Laurier Amundsen Louis St‐Laurent Polarstern

Funding Information:
We wish to acknowledge the assistance of the officers and crew of the USCG Healy, the CCGS Sir Wilfrid Laurier, Amundsen, Louis St-Laurent, and the R/V Polarstern during the research expeditions. Jay Cullen, Philippe Tortell, and Kristina Brown are also acknowledged for their implication in the scientific managing of the 2015 cruise. We are grateful to Pascal Guillot, Thomas Linkowski, and Cris Seaton (Quebec-Ocean and ArcticNet) for their technical support at sea. We thank Cheng Kuang for her great help during the cruise preparation and on-board and Isabelle Baconnais for sampling at sea. We also acknowledge, on the one hand, Vivian Lai and Dominique Weis (Pacific Centre for Isotopic and Geochemical Research, EOAS) and, on the other hand, Stephanie Mounic and Mathieu Benoit (Centre National de la Recherche Scientifique, GET) for their technical support on the ICP-MS and on the TIMS, respectively. Finally, we thank the two anonymous reviewers whose insightful comments and suggestions helped to improve the manuscript. The Canadian Arctic GEOTRACES project was funded by the Canadian research program NSERC CCAR. M. Grenier was supported by a European Union's Horizon 2020 research and innovation programme (Marie Sk?odowska-Curie action, Grant Agreement 657853). Christelle Not was supported by Natural Sciences and Engineering Research Council of Canada research funds awarded to Claude Hillaire-Marcel and the Fonds Qu?b?cois de la Recherche sur la Nature et les Technologies from GEOTOP. The data set reported in the tables is available on the GEOTRACES International Data Assembly Centre (www.bodc.ac.uk/geotraces/data/).

Publisher Copyright:
©2019. The Authors.

Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.

Keywords

  • Amerasian Basin
  • Arctic Ocean
  • lateral exchanges
  • particle flux
  • radioisotopes
  • temporal evolution

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