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- Chierici, Melissa, 1968, et al.
(författare)
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CaCO3 saturation in the Western Arctic Ocean
- 2009
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Ingår i: Gordon Researcg Conference Polar Marine Science, 15-20 March 2009, Il Ciocco, Italy.
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Konferensbidrag (refereegranskat)
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| 5. |
- Chierici, Melissa, 1968
(författare)
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Towards an understanding of the biological forcing of CO2 in the Southern Polar Ocean.
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this project was to quantitatively investigate the mechanisms driving the oceanic carbon dioxide system and the CO2 air-sea flux in areas of different characteristics regarding water column stratification, ice cover/extent and freshwater input in the Pacific sector of the Southern Ocean. The biogeochemical transformation of carbon was evaluated from CO2 system data and information on water mass properties in the water column. Another goal was to investigate the large natural variability of the marine carbonate system in the study area, to provide basic information needed to predict the response to future changes in the CaCO3 saturation in the Southern Ocean due to changes in sea ice extent and temperature.
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| 6. |
- Fransson, Agneta, 1964, et al.
(författare)
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Continuous pCO2 measurements under the sea ice in Arctic and Antarctic waters onboard an icebreaker.
- 2007
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Ingår i: IOCCP Report from Surface Ocean Surface CO2 Variability and Vulnerabilities Workshop, 11-14th April 2007, UNESCO-IOCCP, Paris, France.. ; 7
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- High-frequency underway pCO2 measurements were successfully performed in the Arctic Ocean in 2005, and in the Antarctic Southern Ocean in 2006 onboard the Swedish I/B Oden. We traversed in both open water and heavy sea ice conditions. The seawater intake was placed at the bow of the ship at approximately 8 meters depth, which enabled immediate under ice measurements in ice covered areas. In both studies, preliminary data showed rapid changes in the pCO2 and oxygen values in the ice zones, which was related to physical fronts and changing sea-ice conditions. However, the under-ice pCO2 levels differed in the two high-latitude oceans, likely due to different ecosystem dynamics involving ice-algae versus pelagic phytoplankton production. Future participation in expeditions to Antarctic Southern Ocean, and a long-term study in the Arctic Ocean in 2007/2008 will enable us to further investigate the biogeochemical dynamics in both Polar seas.
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| 8. |
- Torstensson, Anders, et al.
(författare)
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Microalgal photophysiology and macronutrient distribution in summer sea ice in the Amundsen and Ross Seas, Antarctica
- 2018
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 13:4
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Tidskriftsartikel (refereegranskat)abstract
- Our study addresses how environmental variables, such as macronutrients concentrations, snow cover, carbonate chemistry and salinity affect the photophysiology and biomass of Antarctic sea-ice algae. We have measured vertical profiles of inorganic macronutrients (phosphate, nitrite + nitrate and silicic acid) in summer sea ice and photophysiology of ice algal assemblages in the poorly studied Amundsen and Ross Seas sectors of the Southern Ocean. Brine-scaled bacterial abundance, chl a and macronutrient concentrations were often high in the ice and positively correlated with each other. Analysis of photosystem II rapid light curves showed that microalgal cells in samples with high phosphate and nitrite + nitrate concentrations had reduced maximum relative electron transport rate and photosynthetic efficiency. We also observed strong couplings of PSII parameters to snow depth, ice thickness and brine salinity, which highlights a wide range of photoacclimation in Antarctic pack-ice algae. It is likely that the pack ice was in a post-bloom situation during the late sea ice season, with low photosynthetic efficiency and a high degree of nutrient accumulation occurring in the ice. In order to predict how key biogeochemical processes are affected by future changes in sea ice cover, such as in situ photosynthesis and nutrient cycling, we need to understand how physicochemical properties of sea ice affect the microbial community. Our results support existing hypothesis about sea-ice algal photophysiology, and provide additional observations on high nutrient concentrations in sea ice that could influence the planktonic communities as the ice is retreating.
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| 9. |
- Chierici, Melissa, 1968, et al.
(författare)
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Calcium carbonate saturation in the surface water of the Arctic Ocean: undersaturation in freshwater influenced shelves
- 2009
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Ingår i: Biogeosciences. ; 6, s. 2421-2432
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Tidskriftsartikel (refereegranskat)abstract
- In the summer of 2005, we sampled surface water and measured pH and total alkalinity (AT) underway aboard IB Oden along the Northwest Passage from Cape Farewell (South Greenland) to the Chukchi Sea. We investigated the variability of carbonate system parameters, focusing particularly on carbonate concentration [CO32-] and calcium carbonate saturation states, as related to freshwater addition, biological processes and physical upwelling. Measurements on AT, pH at 15 ºC, salinity (S) and sea surface temperature (SST), were used to calculate total dissolved inorganic carbon (CT), [CO32-] and the saturation of aragonite (ΩAr) and calcite (ΩCa) in the surface water. The same parameters were measured in the water column of the Bering Strait. Some surface waters in the Canadian Arctic Archipelago (CAA) and on the Mackenzie shelf (MS) were found to be undersaturated with respect to aragonite (ΩAr < 1). In these areas, surface water was low in AT and CT (< 1500 µmol kg-1) relative to seawater and showed low [CO32-]. The low saturation states were probably due to the likely the effect of dilution due to freshwater addition by sea ice melt (CAA) and river runoff (MS). High AT and CT and low pH, corresponded with the lowest [CO32-], ΩAr and ΩCa, observed near Cape Bathurst and along the South Chukchi Peninsula. This was linked to the physical upwelling of subsurface water with elevated CO2. The highest surface ΩAr and ΩCa of 3.0 and 4.5, respectively, were found on the Chukchi Sea shelf and in the cold water north of Wrangel Island, which is heavily influenced by high CO2 drawdown and lower CT from intense biological production. In the western Bering Strait, the cold and saline Anadyr Current carries water that is enriched in AT and CT from enhanced organic matter remineralization, resulting in the lowest ΩAr (~1.2) of the area.
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