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Author Mock, T.; Dieckmann, G.S.; Haas, C.; Krell, A.; Tison, J.-L.; Belem, A.L.; Papadimitriou, S.; Thomas, D.N. url  openurl
  Title Micro-optodes in sea ice: a new approach to investigate oxygen dynamics during sea ice formation Type Journal Article
  Year 2002 Publication Aquatic Microbial Ecology Abbreviated Journal Aquat Microb Ecol  
  Volume 29 Issue 3 Pages (down) 297-306  
  Keywords Fragilariopsis cylindrus; Oxygen; Methods; Micro-optodes; Sea ice; Biogeochemistry; Diatoms; Algae; Chlorophyll; Photosynthesis; Salinity effects; Sea water; Marine ecosystems; Chlorophylls; Dissolved oxygen; Gases; Epontic environment; Electrodes; Sensors; Brines; Ice-water interface; Ice formation; Bacillariophyceae  
  Abstract Oxygen micro-optodes were used to measure oxygen dynamics directly within the microstructure of sea ice by freezing the sensors into the ice during its formation. The experiment was conducted in a 4 m³ mesocosm filled with artificial seawater and inoculated with a unialgal culture of the common Antarctic ice diatom Fragilariopsis cylindrus (Bacillariophyceae) to a final chlorophyll a (chl a) concentration of 11 µg 1?¹. Ice growth was initiated 7 d after inoculation by reducing the air temperature to -10 plus or minus 2 degree C and terminated 17 d later. The final ice thickness was 27 cm. One optode was frozen into grease ice and 2 others into the skeletal layer of the growing ice sheet. Increasing oxygen concentrations during ice crystal formation at the water surface and the ice-water interface revealed a strong inclusion of oxygen, which was either physically trapped and/or the result of photosynthesising diatoms. The major portion of oxygen was present as gas bubbles due to super-saturation as a result of increasing salinity and oxygen production by diatoms. An increase in salinity due to a concurrent decrease in ice temperatures during subsequent sea ice development reduced the maximum concentration of dissolved oxygen within brine. Thus, dissolved oxygen concentrations decreased over time, whereas gaseous oxygen was released to the atmosphere and seawater. The sensors are a significant advance on more conventional microelectrodes, because the recordings can be temperature and salinity compensated in order to obtain precise measurements of oxygen dynamics with regard to total (dissolved and gaseous) and dissolved oxygen in sea ice. Optodes do not consume oxygen during measuremnet over a long period under extreme conditions, which is another advantage for long-term deployment in the field.  
  Address  
  Corporate Author Thesis  
  Publisher Inter-Research Place of Publication Oldendorf/Luhe Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0948-3055 ISBN Medium  
  Area Expedition Conference  
  Notes Marine Approved no  
  Call Number refbase @ admin @ Mock++2002 Serial 749  
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Author Thomas, D.N.; Kattner, G.; Engbrodt, R.; Giannelli, V.; Kennedy, H.; Haas, C.; Dieckmann, G.S. url  openurl
  Title Dissolved organic matter in Antarctic sea ice Type Journal Article
  Year 2001 Publication Annals of Glaciology Abbreviated Journal Ann Glaciol  
  Volume 33 Issue 1 Pages (down) 297-303  
  Keywords  
  Abstract It has been hypothesized that there are significant dissolved organic matter (DOM) pools in sea-ice systems, although measurements of DOM in sea ice have only rarely been made. The significance of DOM for ice-based productivity and carbon turnover therefore remains highly speculative. DOM within sea ice from the Amundsen and Bellingshausen Seas, Antarctica, in 1994 and the Weddell Sea, Antarctica, in 1992 and 1997 was investigated. Measurements were made on melted sea-ice sections in 1994 and 1997 and in sea-ice brines in 1992. Dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) concentrations in melted ice cores were up to 1.8 and 0.78 mM, respectively, or 30 and 8 times higher than those in surface water concentrations, respectively. However, when concentrations within the brine channel/pore space were calculated from estimated brine volumes, actual concentrations of DOC in brines were up to 23.3 mM and DON up to 2.2 mM, although mean values were 1.8 and 0.15 mM, respectively. There were higher concentrations of DOM in warm, porous summer second-year sea ice compared with colder autumn first-year ice, consistent with the different biological activity supported within the various ice types. However, in general there was poor correlation between DOC and DON with algal biomass and numbers of bacteria within the ice. The mean DOC/DON ratio was 11, although again values were highly variable, ranging from 3 to highly carbon-enriched samples of 95. Measurements made on a limited dataset showed that carbohydrates constitute on average 35% of the DOC pool, with highly variable contributions of 1–99%.  
  Address  
  Corporate Author Thesis  
  Publisher International Glaciological Society Place of Publication Cambridge Editor Intl. Symp. on Sea Ice and its Interaction with the Ocean, A. and B., Fairbanks, Alaska(USA), 19-23 Jun 2000,  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0260-3055 ISBN Medium  
  Area Expedition Conference  
  Notes Conference Approved no  
  Call Number refbase @ admin @ Thomas++2001 Serial 761  
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Author Granskog, M.A.; Virkkunen, K.; Thomas, D.N.; Ehn, J.; Kola, H.; Martma, T. url  openurl
  Title Chemical properties of brackish water ice in the Bothnian Bay, the Baltic Sea Type Journal Article
  Year 2004 Publication Journal of Glaciology Abbreviated Journal J Glaciol  
  Volume 50 Issue 169 Pages (down) 292-302  
  Keywords Dependent Solute Redistribution; Dissolved Organic Matter; Phase Boundary; Sulfate; Binding; Summer; Oxygen; Core; Gulf  
  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.  
  Address Granskog: Univ Helsinki, Dept Phys Sci, Div Geophys, FIN-00014 Helsinki, Finland  
  Corporate Author Thesis  
  Publisher International Glaciological Society Place of Publication Cambridge Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0022-1430 ISBN Medium  
  Area Baltic Sea; Bothnian Bay Expedition Conference  
  Notes ISI:000227720900014 Approved no  
  Call Number refbase @ admin @ Granskog++2004 Serial 741  
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Author Thomas, D.N.; Gleitz, M. url  openurl
  Title Allocation of photoassimilated carbon into major algal metabolite fractions: Variation between two diatom species isolated from the Weddell Sea (Antarctica) Type Journal Article
  Year 1993 Publication Polar Biology Abbreviated Journal Polar Biol  
  Volume 13 Issue 4 Pages (down) 281-286  
  Keywords carbon fixation; metabolites; biomass; Nitzschia curta; Chaetoceros; Psw; Weddell Sea  
  Abstract Distribution of photoassimilated carbon into major metabolite classes differed between two Antarctic diatom species, Nitzschia curta and a small unicellular Chaetoceros sp.. Time course uptake studies (over 54 h) revealed that¹?C allocation appeared to be equilibrated after approximately 8 h at light saturated photosynthesis. During short term dark periods (6 h), polysaccharides as well as low-molecular-weight compounds were catabolised to sustain protein synthesis in the dark, whilst lipid reserves were not mobilised for this process. Experiments with these two species were conducted at 0 and -1.5 degree C, although no difference in the distribution of radiolabel was measured between the two temperatures. It is hypothesised that under near-optimal conditions fast growing species are characterised by a high carbon turnover associated with a rapid flow of newly assimilated carbon into polymeric compound classes. On the other hand, slower growing species (such as N. curta) may store a significant amount of surplus carbon in the low-molecular-weight metabolite fraction. Species specific preferences were observed when comparing the accumulation of radiolabel into the lipid pools.  
  Address  
  Corporate Author Thesis  
  Publisher Springer-Verlag Place of Publication Heidelberg Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0722-4060 ISBN Medium  
  Area Expedition Conference  
  Notes Bibliogr.: 48 ref.; Marine Approved no  
  Call Number refbase @ admin @ Thomas+Gleitz1993 Serial 760  
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Author Granskog, M.A.; Kaartokallio, H.; Kuosa, H.; Thomas, D.N.; Ehn, J.; Sonninen, E. url  doi
openurl 
  Title Scales of horizontal patchiness in chlorophyll a, chemical and physical properties of landfast sea ice in the Gulf of Finland (Baltic Sea) Type Journal Article
  Year 2005 Publication Polar Biology Abbreviated Journal Polar Biol  
  Volume 28 Issue 4 Pages (down) 276-283  
  Keywords  
  Abstract Horizontal variation of first-year landfast sea ice properties was studied in the Gulf of Finland, the Baltic Sea. Several scales of variation were considered; a number of arrays with core spacings of 0.2, 2 and 20 m were sampled at different stages of the ice season for small-scale patchiness. Spacing between these arrays was from hundreds of meters to kilometers to study mesoscale variability, and once an onshore–offshore 40-km transect was sampled to study regional scale variability. Measured variables included salinity, stable oxygen isotopes (δ18O), chlorophyll a (chl-a), nutrients and dissolved organic carbon. On a large scale, a combination of variations in the under-ice water salinity (ice porosity), nutrient supply and the stage of ice development control the build-up of ice algal biomass. At scales of hundreds of meters to kilometers, there was significant variability in several parameters (salinity, chl-a, snow depth and ice thickness). Analyses of the data from the arrays did not show evidence of significant patchiness at scales <20 m for algal biomass. The results imply that the sampling effort in Baltic Sea ice studies should be concentrated on scales of hundreds of meters to kilometers. Using the variations observed in the study area, the estimate for depth-integrated algal biomass in landfast sea ice in the Gulf of Finland (March 2003) is 5.5±4.4 mg chl-a m-2.  
  Address Granskog: Arctic Centre, University of Lapland, P.O. Box 122, 96101 Rovaniemi, Finland  
  Corporate Author Thesis  
  Publisher Springer-Verlag Place of Publication Heidelberg Editor  
  Language English Summary Language English Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0722-4060 ISBN Medium  
  Area Baltic Sea; Gulf of Finland Expedition Conference  
  Notes Approved no  
  Call Number refbase @ admin @ Granskog++2005 Serial 739  
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