Abstract
AbstractA detailed survey of a high Arctic glacier fjord (Kongsfjorden, Svalbard) was carried out in summer 2016, close to the peak of the meltwater season, in order to identify the effects of glacier runoff on nutrient distributions and the carbonate system. Short‐term weather patterns were found to exert a strong influence on freshwater content within the fjord. Freshwater inputs from glacier runoff and ice meltwater averaged (±SD) low nitrate (1.85 ± 0.47 μM; 0.41 ± 0.99 μM), orthophosphate (0.07 ± 0.27 μM; 0.02 ± 0.03 μM), dissolved organic carbon (27 ± 14 μM in glacier runoff), total alkalinity (708 ± 251 μmol kg−1; 173 ± 121 μmol kg−1), and dissolved inorganic carbon (622 ± 108 μmol kg−1; 41 ± 88 μmol kg−1), as well as a modest silicate concentration (3.71 ± 0.02 μM; 3.16 ± 5.41 μM). pCO2 showed a nonconservative behavior across the estuarine salinity gradient with a pronounced undersaturation in the inner‐fjord, leading to strong CO2 uptake from the atmosphere. The combined effect of freshwater dilution and atmospheric CO2 absorption was the lowering of aragonite saturation state to values that are known to negatively affect marine calcifiers (ΩAr, 1.07). Glacier discharge was therefore a strong local amplifier of ocean acidification. Future increases in discharge volume and the loss of marine productivity following the retreat of marine‐terminating glaciers inland are both anticipated to further lower ΩAr within inner‐fjord surface waters. This shift may be partially buffered by an increase in the mean freshwater total alkalinity as the fractional importance of iceberg melt to freshwater fjord inputs declines and runoff increases.
Highlights
The Arctic is a hotspot for the effects of climate change
The earliest hydrological survey (NYA1) was conducted during the phase of snow melting while the six oceanographic surveys of the pHinS project were carried out shortly after the annual peak in TAIR and when snow had completely disappeared from the fjord
Experimental results showed a sharper than calculated ΩAr decrease at low salinities, with a significant ΩAr/S correlation (r2 = 0.80), confirming the trend evidenced in similar fjords elsewhere in Svalbard (Ericson et al, 2019; Fransson et al, 2015)
Summary
The Arctic is a hotspot for the effects of climate change. Atmospheric temperatures are rising 2–3 times faster than other areas around the globe, resulting in loss of sea‐ice coverage of 26% in July and 35% in August between 1979 and 2016 (Onarheim et al, 2018), a retreat of most marine‐terminating glaciers and a loss of glacier and ice sheet volume (Meredith et al, 2019). Journal of Geophysical Research: Biogeosciences alteration of fjord‐scale circulation (Straneo et al, 2011; Torsvik et al, 2019), water column structure (Meire et al, 2017; Sejr et al, 2017), the carbonate system (Fransson et al, 2015; Meire et al, 2015), nutrient concentrations (Kanna et al, 2018; Meire et al, 2016), and light availability to support primary production (Halbach et al, 2019; Murray et al, 2015) These perturbations potentially affect the metabolism of microbes and the structure of coastal plankton communities (Cauvy‐Fraunié & Dangles, 2019; Matsuno et al, 2020) by changing the availability of resources that sustain primary production or instigating changes in the foraging behavior of higher organisms (Arendt et al, 2011; Arimitsu et al, 2012; Lydersen et al, 2014). The intrusion of CO2 rich waters from the Atlantic Ocean (Luo et al, 2016) and the formation of brine (Anderson et al, 2010) further act to increase the CO2 content of the Arctic Ocean (Terhaar et al, 2020)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
