Export of calcium carbonate corrosive waters from the East Siberian Sea

Abstract

Abstract. The Siberian shelf seas are areas of extensive biogeochemical transformation of organic matter, both of marine and terrestrial origin. This in combination with brine production from sea ice formation results in a cold bottom water of relative high salinity and partial pressure of carbon dioxide (pCO 2 ). Data from the SWERUS-C3 expedition compiled on the icebreaker Oden in July to September 2014 show the distribution of such waters at the outer shelf, as well as their export into the deep central Arctic basins. Very high pCO 2 water, up to ∼ 1000 µatm, was observed associated with high nutrients and low oxygen concentrations. Consequently, this water had low saturation state with respect to calcium carbonate down to less than 0.8 for calcite and 0.5 for aragonite. Waters undersaturated in aragonite were also observed in the surface in waters at equilibrium with atmospheric CO 2 ; however, at these conditions the cause of undersaturation was low salinity from river runoff and/or sea ice melt. The calcium carbonate corrosive water was observed all along the continental margin and well out into the deep Makarov and Canada basins at a depth from about 50 m depth in the west to about 150 m in the east. These waters of low aragonite saturation state are traced in historic data to the Canada Basin and in the waters flowing out of the Arctic Ocean north of Greenland and in the western Fram Strait, thus potentially impacting the marine life in the North Atlantic Ocean.

Pteropods counter mechanical damage and dissolution through extensive shell repair

“…The near absence of sea ice during the winter months at Stations 22, 23 and 28 further accounts for persistently supersaturated waters throughout the year. In contrast, the East Greenland Current, exporting Arctic waters, is cold with a low saturation state 33 . In addition, the presence of sea ice at Station 18 further modifies carbonate chemistry in sub-sea ice waters, decreasing Ω Ar over the winter months 26 , meaning Station 18 was likely close to saturation or undersaturated with respect to aragonite during the winter of 2011/2012.…”

Two Decades of Ocean Acidification in the Surface Waters of the Beaufort Gyre, Arctic Ocean: Effects of Sea Ice Melt and Retreat From 1997–2016

“…This was due to a decrease in SIM content in the surface sea waters, while the mean MW remained rather constant since 2003. As the residence time of Arctic surface water is about 10 years (Ekwurzel et al, 2001), the massive freshwater input from multiyear sea ice melt between 2005 and 2007 gradually moved out of the surface layer into deeper layers of the Beaufort Gyre region or to downstream regions (Anderson et al, 2017;McPhee, 2013;Proshutinsky et al, 2009;Qi et al, 2017). Even though summer sea ice coverage has continued to retreat, dilution by SIM should be much smaller now as thinner young sea ice is melting rather than thick multiyear ice (Haas et al, 2008;Hunke & Bitz, 2009;Kwok et al, 2009;Maslanik et al, 2007).…”

Net Community Production and Carbon Exchange From Winter to Summer in the Atlantic Water Inflow to the Arctic Ocean

“…Ocean CO 2 uptake, as an effect of increased atmospheric CO 2 due to the increased emission of CO 2 from human activities (e.g., burning of fossil fuel, deforestation), is causing ocean acidification (OA) in the Arctic Ocean (e.g., AMAP, 2013AMAP, , 2018. In addition, reported release of methane and CO 2 from the Siberian shelves may also contribute to OA in the Arctic (e.g., Semiletov et al, 2012;Anderson et al, 2017;Qi et al, 2017). With continued warming, freshening and changes to primary production, the rate of ocean acidification is expected to increase (AMAP, 2013(AMAP, , 2018).…”