| 1. |
- Anderson, Leif G, 1951, et al.
(författare)
-
Export of calcium carbonate corrosive waters from the East Siberian Sea
- 2017
-
Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 14:7, s. 1811-1823
-
Tidskriftsartikel (refereegranskat)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 similar to 1000 mu atm, 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 CO2; 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.
|
|
| 2. |
- Anderson, Leif G, 1951, et al.
(författare)
-
Shelf-Basin interaction along the East Siberian Sea
- 2017
-
Ingår i: Ocean Science. - : Copernicus GmbH. - 1812-0784 .- 1812-0792. ; 13:2, s. 349-363
-
Tidskriftsartikel (refereegranskat)abstract
- Extensive biogeochemical transformation of organic matter takes place in the shallow continental shelf seas of Siberia. This, in combination with brine production from sea-ice formation, results in cold bottom waters with relatively high salinity and nutrient concentrations, as well as low oxygen and pH levels. Data from the SWERUS-C3 expedition with icebreaker Oden, from July to September 2014, show the distribution of such nutrient-rich, cold bottom waters along the continental margin from about 140 to 180 degrees E. The water with maximum nutrient concentration, classically named the upper halocline, is absent over the Lomonosov Ridge at 140 degrees E, while it appears in the Makarov Basin at 150 degrees E and intensifies further eastwards. At the intercept between the Mendeleev Ridge and the East Siberian continental shelf slope, the nutrient maximum is still intense, but distributed across a larger depth interval. The nutrient-rich water is found here at salinities of up to similar to 34.5, i.e. in the water classically named lower halocline. East of 170 degrees E transient tracers show significantly less ventilated waters below about 150 m water depth. This likely results from a local isolation of waters over the Chukchi Abyssal Plain as the boundary current from the west is steered away from this area by the bathymetry of the Mendeleev Ridge. The water with salinities of similar to 34.5 has high nutrients and low oxygen concentrations as well as low pH, typically indicating decay of organic matter. A deficit in nitrate relative to phosphate suggests that this process partly occurs under hypoxia. We conclude that the high nutrient water with salinity similar to 34.5 are formed on the shelf slope in the Mendeleev Ridge region from interior basin water that is trapped for enough time to attain its signature through interaction with the sediment.
|
|
| 3. |
- Ulfsbo, Adam, 1985, et al.
(författare)
-
Activity coefficients of a simplified seawater electrolyte at varying salinity (5–40) and temperature (0 and 25 °C) using Monte Carlo simulations
- 2015
-
Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 171, s. 78-86
-
Tidskriftsartikel (refereegranskat)abstract
- Mean salt activity coefficients of a simplified seawater electrolyte (Na+, Mg2+, Ca2+, Cl−, SO42−, HCO3−, CO32−) at varying salinity (5–40) and temperature (0–25 °C) were estimated by Monte Carlo (MC) simulations, and compared with Pitzer calculations. The MC simulations used experimentally determined dielectric constants of water at different temperatures, and optimal agreement with the experimental data and the Pitzer calculations was achieved by adjusting the ionic radii. The results, together with a previous study of the carbon dioxide system in sodium chloride solution by the authors, suggest that a complete Monte Carlo description of seawater activity coefficients may be achievable using the charged hard sphere approach with a very limited number of fitted parameters (effective ionic radii), in contrast to the large number of fitted parameters required for a Pitzer model.
|
|
| 4. |
- Ulfsbo, Adam, 1985, et al.
(författare)
-
Modelling organic alkalinity in the Baltic Sea using a Humic-Pitzer approach
- 2015
-
Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 168, s. 18-26
-
Tidskriftsartikel (refereegranskat)abstract
- Significant excess alkalinity, of the order of 30 μmol kg− 1 and attributed to dissolved organic matter, has recently been measured in the Baltic Sea. Chemical speciation modelling shows that the measured excess alkalinity is consistent with an organic alkalinity derived from dissolved organic carbon, assuming that this dissolved organic carbon consists entirely of terrestrial humic substances. The contribution of polydisperse material such as humic substances to titration alkalinity invalidates the assumptions on which the current definition of titration alkalinity is based. It is therefore concluded that alkalinity should currently not be one of the parameters used to characterise the CO2 system in organic-rich waters. The use of a simple relationship to estimate organic alkalinity from the dissolved organic carbon concentration is assessed for the limited Baltic Sea data set currently available.
|
|
| 5. |
- Ulfsbo, Adam, 1985, et al.
(författare)
-
Rapid Changes in Anthropogenic Carbon Storage and Ocean Acidification in the Intermediate Layers of the Eurasian Arctic Ocean: 1996-2015
- 2018
-
Ingår i: Global Biogeochemical Cycles. - : American Geophysical Union (AGU). - 0886-6236. ; 32:9, s. 1254-1275
-
Tidskriftsartikel (refereegranskat)abstract
- The extended multiple linear regression technique is used to determine changes in anthropogenic carbon in the intermediate layers of the Eurasian Basin based on occupations from four cruises between 1996 and 2015. The results show a significant increase in basin-wide anthropogenic carbon storage in the Nansen Basin (0.44-0.73 +/- 0.14 mol Cm-2.year(-1)) and the Amundsen Basin (0.63-1.04 +/- 0.09 mol C.m(-2).year(-1)). Over the last two decades, inferred changes in ocean acidification (0.020-0.055 pH units) and calcium carbonate desaturation (0.05-0.18 units) are pronounced and rapid. These results, together with results from carbonate-dynamic box model simulations and I-129 tracer distribution simulations, suggest that the accumulation of anthropogenic carbon in the intermediate layers of the Eurasian Basin are consistent with increasing concentrations of anthropogenic carbon in source waters of Atlantic origin entering the Arctic Ocean followed by interior transport. The dissimilar distributions of anthropogenic carbon in the interior Nansen and Amundsen Basins are likely due to differences in the lateral ventilation of the intermediate layers by the return flows and ramifications of the boundary current along the topographic boundaries in the Eurasian Basin.
|
|
