Trickle and Treat? The Critical Role of Marine-Terminating Glaciers as Icy Macronutrient Pumps in Polar Regions

Abstract

Nutrient supply to the coastal euphotic zone is critical in sustaining the productivity of ecosystems and provides an important feedback on the carbon cycle via stimulating the biological pump. The supply of coastal nutrients is typically thought to be dominated by terrestrial inputs and upwelling of deep ocean waters. Marine-terminating glaciers can provide nutrients via both mechanisms but the relative importance of each is dependent on complex physical–biogeochemical processes ranging from those in the glacier drainage system to the ice–ocean interface. Constraining these glacial nutrient supply processes in a remote part of the Canadian Arctic Archipelago (CAA) is the focus of a new study by Williams et al. (2021, https://doi.org/10.1029/2021JG006289). Their findings advance our understanding of the role glaciers play in polar nutrient cycling by highlighting significant shallow meltwater pumping of macronutrient-replete marine waters by CAA marine-terminating glaciers into the euphotic zone.