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

A detailed survey of a high Arctic glacier fjord (Kongsfjorden, Svalbard) was carried out insummer 2016, close to the peak of the meltwater season, in order to identify the effects of glacier runoffon nutrient distributions and the carbonate system. Short-term weather patterns were found to exert astrong influence on freshwater content within the fjord. Freshwater inputs from glacier runoff and icemeltwater averaged (±SD) low nitrate (1.85 ± 0.47 ?M; 0.41 ± 0.99 ?M), orthophosphate (0.07 ± 0.27 ?M;0.02±0.03 ?M), dissolved organic carbon (27±14 ?Min glacier runoff), total alkalinity (708±251 ?mol kg-1;173 ± 121 ?mol kg-1), and dissolved inorganic carbon (622 ± 108 ?mol kg-1; 41 ± 88 ?mol kg-1), as well as amodest silicate concentration (3.71 ± 0.02 ?M; 3.16 ± 5.41 ?M). pCO2 showed a nonconservative behavioracross the estuarine salinity gradient with a pronounced undersaturation in the inner-fjord, leading to strongCO2 uptake from the atmosphere. The combined effect of freshwater dilution and atmospheric CO2absorption was the lowering of aragonite saturation state to values that are known to negatively affect marinecalcifiers (?Ar, 1.07). Glacier discharge was therefore a strong local amplifier of ocean acidification. Futureincreases in discharge volume and the loss of marine productivity following the retreat of marine-terminatingglaciers inland are both anticipated to further lower ?Ar within inner-fjord surface waters. This shiftmay be partially buffered by an increase in the mean freshwater total alkalinity as the fractional importance oficeberg melt to freshwater fjord inputs declines and runoff increases.