Glacial drivers of marine biogeochemistry indicate a future shift to more corrosive conditions in an Arctic fjord

Plain Language Summary. During summer 2016, we surveyed a glacier fjord in the Svalbard archipelago to study the effect of glaciers on the marine ecosystem over the melting season. We measured the quantities of the dissolved nutrients that can potentially fertilize downstream waters in watercourses fed by glacier discharge and in small icebergs calved from marine-terminating glaciers in the fjord. All these sources of freshwater had negative (diluting) or modest fertilizing effects, as the quantities of most nutrients were lower than that in marine waters. Glacier-derived freshwater also had limited concentrations of carbonates derived from limestone erosion, hence mixing between fresh and saline waters created favorable conditions for the absorption of carbon dioxide from the atmosphere. This process further increased the corrosivity of surface fjord waters creating conditions that are not suitable for some organisms that produce carbonate shells. Future glacier retreat will change both the fjord circulation and the freshwater properties. These modifications are expected to further increase the corrosivity of surface waters, locally amplifying the ocean acidification process caused by increasing concentrations of atmospheric carbon dioxide.