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Author |
Granskog, M.A.; Virkkunen, K.; Thomas, D.N.; Ehn, J.; Kola, H.; Martma, T. |
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Title |
Chemical properties of brackish water ice in the Bothnian Bay, the Baltic Sea |
Type |
Journal Article |
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Year |
2004 |
Publication  |
Journal of Glaciology |
Abbreviated Journal |
J Glaciol |
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Volume |
50 |
Issue |
169 |
Pages |
292-302 |
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Keywords |
Dependent Solute Redistribution; Dissolved Organic Matter; Phase Boundary; Sulfate; Binding; Summer; Oxygen; Core; Gulf |
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Abstract |
The behavior of majors, δ18O, dissolved organic carbon (DOC) and trace elements was studied during the initial freezing of low-saline water (3 practical salinity units) in a freezing experiment. Samples were also collected from first-year sea ice from pack ice in the Bothnian Bay, northern Baltic Sea. During initial ice formation, the major-ion ratios in sea ice indicated variable behavior, with some ions showing relative enrichment (sulfate, calcium and magnesium), conservative behavior (sodium) or relative depletion (potassium) compared to sea water at the same salinity DOC, iron and aluminum showed enrichment in the ice, while zinc was depleted to salinity. Lead was detected in surface snow-ice layers only, implying atmospheric accumulation. First-year sea ice, with a variable growth and thermal history, showed behavior for major ions similar to that observed in new ice. However, for trace elements the picture was much more complicated, most likely due to active secondary processes such as atmospheric supply and biological activity. Ice growth has a potential impact on the chemical budgets and cycling of some elements, especially those which are selectively rejected/retained during sea-ice formation, particularly in the shallow parts of the Bothnian Bay covered with a land-fast ice cover. |
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Address |
Granskog: Univ Helsinki, Dept Phys Sci, Div Geophys, FIN-00014 Helsinki, Finland |
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Publisher |
International Glaciological Society |
Place of Publication |
Cambridge |
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ISSN |
0022-1430 |
ISBN |
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Area |
Baltic Sea; Bothnian Bay |
Expedition |
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Conference |
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Notes |
ISI:000227720900014 |
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no |
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Call Number |
refbase @ admin @ Granskog++2004 |
Serial |
741 |
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Author |
Haas, C.; Thomas, D.N.; Bareiss, J. |
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Title |
Surface properties and processes of perennial Antarctic sea ice in summer |
Type |
Journal Article |
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Year |
2001 |
Publication |
Journal of Glaciology |
Abbreviated Journal |
J Glaciol |
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Volume |
47 |
Issue |
159 |
Pages |
613-625 |
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Keywords |
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Abstract |
Ice-core and snow data from the Amundsen, Bellingshausen and Weddell Seas, Antarctica, show that the formation of superimposed ice and the development of seawater-filled gap layers with high algal standing stocks is typical of the perennial sea ice in summer. The coarse-grained and dense snow had salinities mostly below 0.1ppt. A layer of fresh superimposed ice had a mean thickness of 0.04-0.12 m. Gap layers 0.04-0.08 m thick extended downwards from 0.02 to 0.14 m below the water level. These gaps were populated by diatom standing stocks up to 439 ?g L?¹ chlorophyll a. We propose a comprehensive heuristic model of summer processes, where warming and the reversal of temperature gradients cause major transformations in snow and ice properties. The warming also causes the reopening of incompletely frozen slush layers caused by flood-freeze cycles during winter. Alternatively, superimposed ice forms at the cold interface between snow and slush in the case of flooding with negative freeboard. Combined, these explain the initial formation of gap layers by abiotic means alone. The upward growth of superimposed ice above the water level competes with a steady submergence of floes due to bottom and internal melting and accumulation of snow. |
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Publisher |
International Glaciological Society |
Place of Publication |
Cambridge |
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ISSN |
0022-1430 |
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Notes |
IPØ/Tvärrminne |
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no |
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Call Number |
refbase @ admin @ Haas++2001 |
Serial |
742 |
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Author |
Gleitz, M.; Rutgers v d Loeff, M.; Thomas, D.N.; Dieckmann, G.S.; Millero, F.J. |
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Title |
Comparison of summer and winter inorganic carbon, oxygen and nutrient concentrations in Antarctic sea ice brine |
Type |
Journal Article |
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Year |
1995 |
Publication |
Marine Chemistry |
Abbreviated Journal |
Mar Chem |
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Volume |
51 |
Issue |
2 |
Pages |
81-91 |
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Keywords |
dissolved oxygen; inorganic compounds; summer; winter; nutrients (mineral); Antarctic zone; sea ice; brines; carbon; chemical composition; Psw; Weddell Sea; polar zones; polar regions; nutrients |
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Abstract |
During summer (January 1991) and winter (April 1992) cruises to the southern Weddell Sea (Antarctica), brine samples were collected from first year sea ice and analysed for salinity, temperature, dissolved oxygen and major nutrient concentrations. Additionally, the carbonate system was determined from measurements of pH and total alkalinity. During winter, brine chemical composition was largely determined by seawater concentration in the course of freezing. Brine temperatures ranged from -1.9 to -6.7 °C. Precipitation of calcium carbonate was not observed at the corresponding salinity range of 34 to 108. Removal of carbon from the total inorganic carbon pool (up to 500 µmol Ct kg?¹) was related to reduced nutrient concentrations, indicating the presence of photosynthetically active ice algal assemblages in the winter sea ice. However, nutrient and inorganic carbon concentrations did generally not reach growth limiting levels for phytoplankton. The combined effect of photosynthesis and physical concentration resulted in O? concentrations of up to 650 µmol kg?¹. During summer, brine salinities ranged from 21 to 41 with most values >28, showing that the net effect of freezing and melting on brine chemical composition was generally slight. Opposite to the winter situation, brine chemical composition was strongly influenced by biological activity. Photosynthetic carbon assimilation resulted in a Ct depletion of up to 1200 µmol kg?¹, which was associated with CO? (aq) exhaustion and O? concentrations as high as 933 µmol kg?¹. The concurrent depletion of major nutrients generally corresponded to uptake ratios predicted from phytoplankton biochemical composition. Primary productivity in summer sea ice is apparently sustained until inorganic resources are fully exhausted, resulting in brine chemical compositions that differ profoundly from those of surface waters. This may have important implications for pathways of ice algal carbon acquisition, carbon isotope fractionation as well as for species distribution in the open water phytoplankton. |
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Publisher |
Elsevier Science B.V. |
Place of Publication |
Amsterdam |
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Series Volume |
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Edition |
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ISSN |
0304-4203 |
ISBN |
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Notes |
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no |
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Call Number |
refbase @ admin @ Gleitz++1995 |
Serial |
733 |
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Author |
Gleitz, M.; Thomas, D.N. |
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Title |
Physiological responses of a small Antarctic diatom (Chaetoceros sp.) to simulated environmental constraints associated with sea-ice formation |
Type |
Journal Article |
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Year |
1992 |
Publication |
Marine Ecology Progress Series |
Abbreviated Journal |
Mar Ecol Prog Ser |
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Volume |
88 |
Issue |
2-3 |
Pages |
271-278 |
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Keywords |
plant physiology; abiotic factors; temperature effects; salinity effects; irradiance; sea ice; growth; photosynthesis; Chaetoceros; Psw; Weddell Sea; simulation |
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Abstract |
The physiological responses of a small unicellular Chaetoceros species, isolated from the Weddell Sea, Antarctica, to changes in temperature, salinity and irradiance simulating those that occur during new-ice formation were investigated. The combination of increased salinity, increased quantum irradiance and decreased temperature significantly reduced growth and photosynthetic rates compared to the control, although cellular metabolism was not inhibited. The cells retained the capacity to photoacclimate, which was observed in the variations in cellular chlorophyll a concentrations and carbon allocation patterns. In terms of photosynthesis, a doubling of quantum irradiance apparently compensated for the adverse effects of increased salinity and lowered temperature. It is thus hypothesized that at least some species of the late season phytoplankton population survive incorporation into ice and continue to photosynthesize and grow under the extreme conditions encountered during sea-ice formation. |
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Corporate Author |
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Thesis |
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Publisher |
Inter-Research |
Place of Publication |
Oldendorf/Luhe |
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Summary Language |
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Original Title |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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ISSN |
0171-8630 |
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Notes |
Bibliogr.: 38 ref.; Marine |
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no |
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Call Number |
refbase @ admin @ Gleitz+Thomas1992 |
Serial |
735 |
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Author |
Kattner, G.; Thomas, D.N.; Haas, C.; Kennedy, H.; Dieckmann, G.S. |
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Title |
Surface ice and gap layers in Antarctic sea ice: highly productive habitats |
Type |
Journal Article |
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Year |
2004 |
Publication |
Marine Ecology Progress Series |
Abbreviated Journal |
Mar Ecol Prog Ser |
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Volume |
277 |
Issue |
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Pages |
1-12 |
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Keywords |
Antarctic sea ice; Gap layers; Biogeochemistry; Particulate organic matter; Dissolved organic matter; Chlorophyll a; Nutrients |
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Abstract |
Biogeochemical investigations of the upper layers of sea ice were made on layered summer ice floes collected from the Weddell Sea, Antarctica, from mid-February to March 1997. The surface layers had a clearly defined bottom layer immediately overlying a gap filled with seawater. Generally the gap covered rotten sea ice below. Using differences in algal biomass, mostly in the bottom layer of the surface ice overlying the gap, the floes were classified as low, moderate or high biomass. In addition, a floe with a re-frozen gap layer was studied. In the floes with the highest biomass, particulate organic carbon (POC) and nitrogen (PON) reached concentrations of up to 6000 µMC and 600 µMN in the bottom layer. In the upper part of the surface ice layer and the gap water, particulate and dissolved organic matter concentrations (POM, DOM) were clearly lower. High concentrations of POM were generally accompanied by high values of DOM although POM values generally exceeded DOM. All C and N contents of organic matter were significantly correlated. In gap waters, POM was low but still clearly higher than in the surrounding seawater, whereas DOM was in the range of seawater concentrations. Most POC/PON and C/chlorophyll a ratios pointed to an actively growing algae community, whereas the higher and more variable DOC/DON ratios reflected the various sources influencing DOM composition. Nitrate and silicate closely followed the signature of salinity, reaching in some gap water samples values similar to seawater concentrations. In some samples, in particular from the upper part of the surface ice layer, nitrate was totally exhausted. The distribution of the regenerated nutrients ammonium and phosphate was totally different from that of nitrate and silicate, reaching values of up to 15.9 and 9.08 µM, respectively. The bottom ice layer of the floe with the re-frozen gap layer had a high biomass similar to that of the high-biomass ice floe. DOC concentrations were lower, and DON maximum was not clearly linked with DOC maximum, but instead was associated with high ammonium and phosphate concentrations. The significant correlations between POM and DOM as well as between nitrate and silicate and between the regenerated nutrients ammonium and phosphate indicate that the gap-layer floes are semi-enclosed, highly productive habitats that still maintain high biomass during freezing. They are ubiquitous in the Antarctic pack-ice zone and important features that support high algae standing stocks. |
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Corporate Author |
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Thesis |
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Publisher |
Inter-Research |
Place of Publication |
Oldendorf/Luhe |
Editor |
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Summary Language |
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Original Title |
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ISSN |
0171-8630 |
ISBN |
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Notes |
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no |
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Call Number |
refbase @ admin @ Kattner++2004 |
Serial |
745 |
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