| 1. |
- Anderson, Leif G, 1951, et al.
(författare)
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Variability in river runoff distribution in the Eurasian Basin of the Arctic Ocean
- 2004
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Ingår i: Journal of Geophysical Research-Oceans. - 0148-0227. ; 109:C1
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Tidskriftsartikel (refereegranskat)abstract
- The distribution of freshwater within the Arctic Ocean and its export from it are intimately involved in climate and climate change processes both within and outside the Arctic Ocean. River runoff in the Arctic Ocean constitutes a major part of the Arctic Ocean freshwater budget. Within the Arctic Ocean, variability in the distribution of river runoff will be reflected in the location of the cold halocline that isolates the sea ice from the warm Atlantic Layer. Outside the Arctic Ocean, such variability will impact on the salinity of North Atlantic waters (Great Salinity Anomaly) and on deep convection areas of the North Atlantic Ocean, and thereby potentially on global thermohaline circulation. Rivers entering the Arctic Ocean have high levels of total alkalinity that contribute significantly to the total alkalinity of the surface Polar Mixed Layer. We exploit total alkalinity data to trace river runoff in the surface Polar Mixed Layer and to observe variability in the river runoff distribution in the Eurasian Basin over the period 1987-2001. The river runoff front changed from a position over the Gakkel Ridge in 1987 and 1991 to over the Lomonosov Ridge in 1996, and returned to a midpoint between the two ridges in 2001. Wind field changes as characterized by the Arctic Oscillation index are considered to be a major factor in determining ice and surface water flow. We note a correlation with 4-6 years delay between changes in river runoff distribution and the Arctic Oscillation index. We show that the delay can be inferred from a geostrophic flow calculation.
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| 2. |
- Kaltin, Staffan, et al.
(författare)
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A rapid method for determination of total dissolved inorganic carbon in seawater with high accuracy and precision
- 2005
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Ingår i: Marine Chemistry. ; 96:1-2, s. 53-60
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Tidskriftsartikel (refereegranskat)abstract
- A rapid method for determination of total dissolved inorganic carbon (CT) in seawater with high accuracy and precision has been developed. The method is based on continuous gas extraction of acidified seawater that is pumped through an extraction chamber at a constant flow rate. The purged carbon dioxide is determined with a NDIR gas analyser. A high accuracy was achieved by continually shifting between sample and a certified reference material in 2-min intervals. The method was compared with the current standard, the coulometric technique. Seawater samples having CT-concentrations between 1950 and 2160 μmol kg−1 were analysed and the results for the two methods showed good correlation (linear regression equalled CTcoul=1.0011*CTNDIR−4.28,R2=0.99994). Precision was comparable, with the method presented having a standard deviation of 0.05% and the coulometric having 0.08%. However the proposed method is faster than the coulometric method having a rate of about 12 samples per hour using a sample volume of less than 50 ml. Furthermore the hazardous chemicals associated with the coulometric technique are not needed.
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| 3. |
- Kaltin, Staffan, et al.
(författare)
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Uptake of atmospheric carbon dioxide in Arctic shelf seas: evaluation of the relative importance of processes that influence pCO2 in water transported over the Bering–Chukchi Sea shelf
- 2005
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Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 94:1-4, s. 67-79
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Tidskriftsartikel (refereegranskat)abstract
- The uptake of atmospheric carbon dioxide in the water transported over the Bering–Chukchi shelves has been assessed from the change in carbon-related chemical constituents. The calculated uptake of atmospheric CO2 from the time that the water enters the Bering Sea shelf until it reaches the northern Chukchi Sea shelf slope (1 year) was estimated to be 86±22 g C m−2 in the upper 100 m. Combining the average uptake per m3 with a volume flow of 0.83×106 m3 s−1 through the Bering Strait yields a flux of 22×1012 g C year−1. We have also estimated the relative contribution from cooling, biology, freshening, CaCO3 dissolution, and denitrification for the modification of the seawater pCO2 over the shelf. The latter three had negligible impact on pCO2 compared to biology and cooling. Biology was found to be almost twice as important as cooling for lowering the pCO2 in the water on the Bering–Chukchi shelves. Those results were compared with earlier surveys made in the Barents Sea, where the uptake of atmospheric CO2 was about half that estimated in the Bering–Chukchi Seas. Cooling and biology were of nearly equal significance in the Barents Sea in driving the flux of CO2 into the ocean. The differences between the two regions are discussed. The loss of inorganic carbon due to primary production was estimated from the change in phosphate concentration in the water column. A larger loss of nitrate relative to phosphate compared to the classical ΔN/ΔP ratio of 16 was found. This excess loss was about 30% of the initial nitrate concentration and could possibly be explained by denitrification in the sediment of the Bering and Chukchi Seas.
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