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 Svalbardarchipelago to study the effect of glaciers on the marine ecosystem over the melting season. We measuredthe quantities of the dissolved nutrients that can potentially fertilize downstream waters in watercourses fedby glacier discharge and in small icebergs calved from marine-terminating glaciers in the fjord. All thesesources of freshwater had negative (diluting) or modest fertilizing effects, as the quantities of most nutrientswere lower than that in marine waters. Glacier-derived freshwater also had limited concentrations ofcarbonates derived from limestone erosion, hence mixing between fresh and saline waters created favorableconditions for the absorption of carbon dioxide from the atmosphere. This process further increased thecorrosivity of surface fjord waters creating conditions that are not suitable for some organisms that producecarbonate 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 amplifyingthe ocean acidification process caused by increasing concentrations of atmospheric carbon dioxide.