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Author |
Stedmon, C.A.; Thomas, D.N.; Granskog, M.; Kaartokallio, H.; Papadimitriou, S.; Kuosa, H. |
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Title |
Characteristics of dissolved organic matter in Baltic coastal sea ice: allochthonous or autochthonous origins? |
Type |
Journal Article |
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Year |
2007 |
Publication |
Environmental Science & Technology |
Abbreviated Journal |
Environ Sci Technol |
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Volume |
41 |
Issue |
21 |
Pages |
7273-7279 |
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Keywords |
Carbon/analysis; *Humic Substances; Ice Cover/*chemistry; Nitrogen/analysis; Oceans and Seas; Spectrometry, Fluorescence |
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Abstract |
The origin of dissolved organic matter (DOM) within sea ice in coastal waters of the Baltic Sea was investigated using parallel factor (PARAFAC) analysis of DOM fluorescence. Sea ice DOM had distinctly different fluorescence characteristics than that of the underlying humic-rich waters and was dominated by protein-like fluorescence signals. PARAFAC analysis identified five fluorescent components, all of which were present in both sea ice and water. Three humic components were negatively correlated to salinity and concluded to be terrestrially derived material. Baltic Sea ice DOM was found to be a mixture of humic material from the underlying water column incorporated during ice formation and autochthonous material produced by organisms within the ice. Dissolved organic carbon (DOC) and nitrogen (DON) concentrations were correlated to the humic fluorescence, indicating that the majority of the organic carbon and nitrogen in Baltic Sea ice is bound in terrestrial humic material trapped within the ice. This has implications for our understanding of sea ice carbon cycling in regions influenced by riverine input (e.g., Baltic and Arctic coastal waters), as the susceptibility of DOM to degradation and remineralization is largely determined by its source. |
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Address |
Department of Marine Ecology, National Environmental Research Institute, University of Aarhus, Frederiksborgvej 399, 4000 Roskilde, Denmark. cst@dmu.dk |
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English |
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0013-936X |
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Notes |
PMID:18044499 |
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Call Number |
refbase @ user @ |
Serial |
12979 |
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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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Inter-Research |
Place of Publication |
Oldendorf/Luhe |
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0171-8630 |
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Notes |
Bibliogr.: 38 ref.; Marine |
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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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Inter-Research |
Place of Publication |
Oldendorf/Luhe |
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0171-8630 |
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Call Number |
refbase @ admin @ Kattner++2004 |
Serial |
745 |
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Author |
Kennedy, H.; Thomas, D.N.; Kattner, G.; Haas, C.; Dieckmann, G.S. |
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Title |
Particulate organic matter in Antarctic summer sea ice: concentration and stable isotopic composition |
Type |
Journal Article |
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Year |
2002 |
Publication |
Marine Ecology Progress Series |
Abbreviated Journal |
Mar Ecol Prog Ser |
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Volume |
238 |
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1-13 |
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Keywords |
Pom; Anarctic sea ice; ice microalgae; carbon isotopic composition |
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Abstract |
The chemical and isotopic data from sea ice collected over a wide area of the Weddell Sea, Antarctica, during the austral summer/early autumn illustrate the range of environmental conditions under which ice algae grow. A range of ice types and features were sampled including intact and layered ice floes and surface ponds. Sea ice communities were found in all these environments but the highest biomasses were found either at the base of ice floes, or in the interior of layered floes with quasi-continuous horizontal gaps at or shortly below the water level. In the layered floes, particulate organic carbon (POC) measured in the ice layer immediately overlying the gap water (280 to 6014 µmol dm?³) was in excess of what would be predicted if algal growth had occurred in a closed environment. The chemical composition of the gap water was strongly affected by biological activity in the overlying ice, which acts as a physical support for the algae retained within its matrix. The lowest range of POC (27 to 739 µmol dm?³) conformed to predictions of algal growth in a closed system and samples were collected from the interior of ice floes where there was essentially no potential for nutrient exchange. The surface ponds displayed nitrate (NO³?) exhaustion and total dissolved inorganic carbon (?CO?) reductions consistent with nutrient limited algal growth. The stable carbon isotopic composition of the particulate organic matter (POM) across all habitat types sampled (?¹³CPOC -10.0 to -27.3?) displayed a wide range but was much less variable than the range of POC concentrations might have implied. The assumption that the highest biomass of algae in sea ice will result in the most positive ?¹³CPOC values cannot be generally applied. The isotopic composition of dissolved inorganic carbon (?¹³C?CO?) in gap waters and surface ponds varied from 0.15 to 3.0? and was shown to be commensurate with the changes predicted from NO³? deficits caused by algal growth. |
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Inter-Research |
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Oldendorf/Luhe |
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0171-8630 |
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Call Number |
refbase @ admin @ Kennedy++2002 |
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746 |
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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 |
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Baltic Sea; Bothnian Bay |
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Notes |
ISI:000227720900014 |
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Call Number |
refbase @ admin @ Granskog++2004 |
Serial |
741 |
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