Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 13, issue 16
Biogeosciences, 13, 4659–4671, 2016
https://doi.org/10.5194/bg-13-4659-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 13, 4659–4671, 2016
https://doi.org/10.5194/bg-13-4659-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 19 Aug 2016

Research article | 19 Aug 2016

Inorganic carbon cycling and biogeochemical processes in an Arctic inland sea (Hudson Bay)

William J. Burt1,2, Helmuth Thomas1, Lisa A. Miller3, Mats A. Granskog4, Tim N. Papakyriakou5, and Leah Pengelly1 William J. Burt et al.
  • 1Department of Oceanography, Dalhousie University, Halifax, Nova Scotia, Canada
  • 2Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, British Columbia, Canada
  • 3Institute of Ocean Sciences, Fisheries and Oceans Canada, Sidney, British Columbia, Canada
  • 4Norwegian Polar Institute, Fram Centre, 9296 Tromsø, Norway
  • 5Centre for Earth Observation Science, University of Manitoba, Winnipeg, Manitoba, Canada

Abstract. The distributions of carbonate system parameters in Hudson Bay, which not only receives nearly one-third of Canada's river discharge but is also subject to annual cycles of sea-ice formation and melt, indicate that the timing and magnitude of freshwater inputs play an important role in carbon biogeochemistry and acidification in this unique Arctic ecosystem. This study uses basin-wide measurements of dissolved inorganic carbon (DIC) and total alkalinity (TA), as well as stable isotope tracers (δ18O and δ13CDIC), to provide a detailed assessment of carbon cycling processes within the bay. Surface distributions of carbonate parameters reveal the particular importance of freshwater inputs in the southern portion of the bay. Based on TA, we surmise that the deep waters in the Hudson Bay are largely of Pacific origin. Riverine TA end-members vary significantly both regionally and with small changes in near-surface depths, highlighting the importance of careful surface water sampling in highly stratified waters. In an along-shore transect, large increases in subsurface DIC are accompanied by equivalent decreases in δ13CDIC with no discernable change in TA, indicating a respiratory DIC production on the order of 100 µmol kg−1 DIC during deep water circulation around the bay.

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This study assesses the state of the carbon cycle in Hudson Bay, an ecologically important region of the Canadian Arctic. Results show that river input, sea-ice melt, biological activity, and general circulation patterns all have significant, and regionally dependent, impacts on the carbon cycle. The study also highlights the importance of detailed sampling procedures in highly stratified waters, and reveals that the deep Hudson Bay is primarily filled with waters of Pacific origin.
This study assesses the state of the carbon cycle in Hudson Bay, an ecologically important...
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