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Oceanic fingerprints of continental and glacial terrestrial runoff in Inuit Nunangat, the Canadian Arctic Archipelago
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  • Birgit Rogalla,
  • Susan E. Allen,
  • Manuel Colombo,
  • Paul G. Myers,
  • Kristin J. Orians
Birgit Rogalla
University of British Columbia

Corresponding Author:[email protected]

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Susan E. Allen
University of British Columbia
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Manuel Colombo
Woods Hole Oceanographic Institution
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Paul G. Myers
University of Alberta
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Kristin J. Orians
University of British Columbia
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Abstract

Arctic river discharge and terrestrial runoff are observed, and forecasted to continue, changing dramatically due to climate change. Rising temperatures and an acceleration of the hydrological cycle are increasing discharge, causing permafrost thaw, glacial melt, and a shift to a groundwater-dominated system. These changes are funnelled to coastal regions of the Arctic Ocean where the implications for the distributions of nutrients and biogeochemical components are unclear. In this study, we investigate the impact of terrestrial runoff on marine biogeochemistry in Inuit Nunangat (the Canadian Arctic Archipelago) — a key pathway for transport and modification of waters from the Arctic Ocean to the North Atlantic — using sensitivity experiments from 2002-2020 with an ocean model of manganese (Mn). The micronutrient Mn traces terrestrial runoff and the modification of geochemical constituents of runoff during transit. The heterogeneity in Arctic river composition creates distinct oceanic fingerprints of influence: continental runoff influences the southwestern Archipelago, glacial runoff dominates the northeast, and their influence overlaps in central Parry Channel. Glacial runoff carries micronutrients southward from Nares Strait in the late summer and may help support long phytoplankton blooms in the Pikialasorsuaq polynya. Enhanced glacial runoff may increase micronutrients delivered downstream to Baffin Bay, accounting for up to 18% of Mn fluxes seasonally and 6% annually. These findings highlight how climate induced changes to terrestrial runoff impact the geochemical composition of the marine environment, and will help to predict the extent of these impacts as a result of ongoing alterations of the Arctic hydrological cycle.