Oceanic fingerprints of continental and glacial terrestrial runoff in
Inuit Nunangat, the Canadian Arctic Archipelago
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.