toggle visibility Search & Display Options

Select All    Deselect All
 |   | 
Details
  Records Links
Author Steffens, M.; Granskog, M.A.; Kaartokallio, H.; Kuosa, H.; Luodekari, K.; Papadimitriou, S.; Thomas, D.N. url  openurl
  Title Spatial variation of biogeochemical properties of landfast sea ice in the Gulf of Bothnia, Baltic Sea Type Conference Article
  Year 2006 Publication Annals of Glaciology Abbreviated Journal Ann Glaciol  
  Volume 44 Issue 1 Pages 80-87  
  Keywords Sea ice; Fast ice; Sea ice properties; Ice algae; Chlorophyll; Biogeochemistry; Nutrients (mineral); Particulate organic matter; Dissolved organic matter; Salinity; Spatial scale; Spatial variability; Horizontal patchiness; Sampling design; Brackish water; Ane; Baltic Sea; Gulf of Bothnia  
  Abstract Horizontal variation of landfast sea-ice properties was studied in the Gulf of Bothnia, Baltic Sea, during March 2004. In order to estimate their variability among and within different spatial levels, 72 ice cores were sampled on five spatial scales (with spacings of 10 cm, 2.5 m, 25 m, 250 m and 2.5 km) using a hierarchical sampling design. Entire cores were melted, and bulk-ice salinity, concentrations of chlorophyll a (Chl a), phaeophytin (Phaeo), dissolved nitrate plus nitrite (DIN) as well as dissolved organic carbon (DOC) and nitrogen (DON) were determined. All sampling sites were covered by a 5.5-23 cm thick layer of snow. Ice thicknesses of cores varied from 26 to 58 cm, with bulk-ice salinities ranging between 0.2 and 0.7 as is typical for Baltic Sea ice. Observed values for Chl a (range: 0.8-6.0 μg Chl a l-1; median: 2.9 μg Chl a l -1) and DOC (range: 37-397 μM; median: 95 μM) were comparable to values reported by previous sea-ice studies from the Baltic Sea. Analysis of variance among different spatial levels revealed significant differences on the 2.5 km scale for ice thickness, DOC and Phaeo (with the latter two being positively correlated with ice thickness). For salinity and Chl a, the 250 m scale was found to be the largest scale where significant differences could be detected, while snow depth only varied significantly on the 25 m scale. Variability on the 2.5 m scale contributed significantly to the total variation for ice thickness, salinity, Chl a and DIN. In the case of DON, none of the investigated levels exhibited variation that was significantly different from the considerable amount of variation found between replicate cores. Results from a principal component analysis suggest that ice thickness is one of the main elements structuring the investigated ice habitat on a large scale, while snow depth, nutrients and salinity seem to be of secondary importance.  
  Address (up)  
  Corporate Author Thesis  
  Publisher International Glaciological Society Place of Publication Cambridge Editor  
  Language English Summary Language English Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0260-3055 ISBN Medium  
  Area Baltic Sea; Gulf of Bothnia Expedition Conference International Symposium on Sea Ice, Dunedin (New Zealand), 5-9 Dec 2005  
  Notes Approved no  
  Call Number refbase @ admin @ Steffens++2006 Serial 754  
Permanent link to this record
 

 
Author Thomas, D.N. url  doi
openurl 
  Title Photosynthetic microbes in freezing deserts Type Journal Article
  Year 2005 Publication Trends in Microbiology Abbreviated Journal Trends Microbiol  
  Volume 13 Issue 3 Pages 87-88  
  Keywords  
  Abstract Polar deserts are not devoid of life despite the extreme low temperature and scarcity of water. Recently, patterned stone fields – caused by periglacial activity – have been surveyed in the Arctic and Antarctic. It was found that the productivity of the cyanobacteria and algae (hypoliths) that colonise the underside of the stones is strongly related to the pattern of the stones. The hypolith assemblages were in some cases as productive as lichens, bryophytes and plants that resided nearby.  
  Address (up)  
  Corporate Author Thesis  
  Publisher Elsevier Science B.V. Place of Publication Amsterdam Editor  
  Language English Summary Language English Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0966-842X ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number refbase @ admin @ Thomas2005 Serial 755  
Permanent link to this record
 

 
Author Lakaniemi, A.-M.; Hulatt, C.J.; Thomas, D.N.; Tuovinen, O.H.; Puhakka, J.A. url  doi
openurl 
  Title Biogenic hydrogen and methane production from Chlorella vulgaris and Dunaliella tertiolecta biomass Type Journal Article
  Year 2011 Publication Biotechnology for Biofuels Abbreviated Journal Biotechnol Biofuels  
  Volume 4 Issue 1 Pages 34  
  Keywords  
  Abstract BACKGROUND: Microalgae are a promising feedstock for biofuel and bioenergy production due to their high photosynthetic efficiencies, high growth rates and no need for external organic carbon supply. In this study, utilization of Chlorella vulgaris (a fresh water microalga) and Dunaliella tertiolecta (a marine microalga) biomass was tested as a feedstock for anaerobic H2 and CH4 production. RESULTS: Anaerobic serum bottle assays were conducted at 37 degrees C with enrichment cultures derived from municipal anaerobic digester sludge. Low levels of H2 were produced by anaerobic enrichment cultures, but H2 was subsequently consumed even in the presence of 2-bromoethanesulfonic acid, an inhibitor of methanogens. Without inoculation, algal biomass still produced H2 due to the activities of satellite bacteria associated with algal cultures. CH4 was produced from both types of biomass with anaerobic enrichments. Polymerase chain reaction-denaturing gradient gel electrophoresis profiling indicated the presence of H2-producing and H2-consuming bacteria in the anaerobic enrichment cultures and the presence of H2-producing bacteria among the satellite bacteria in both sources of algal biomass. CONCLUSIONS: H2 production by the satellite bacteria was comparable from D. tertiolecta (12.6 ml H2/g volatile solids (VS)) and from C. vulgaris (10.8 ml H2/g VS), whereas CH4 production was significantly higher from C. vulgaris (286 ml/g VS) than from D. tertiolecta (24 ml/g VS). The high salinity of the D. tertiolecta slurry, prohibitive to methanogens, was the probable reason for lower CH4 production.  
  Address (up) Department of Chemistry and Bioengineering, Tampere University of Technology, PO Box 541, FI-33101 Tampere, Finland. aino-maija.lakaniemi@tut.fi  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1754-6834 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:21943287; PMCID:PMC3193024 Approved no  
  Call Number refbase @ user @ Serial 12985  
Permanent link to this record
 

 
Author Lakaniemi, A.-M.; Hulatt, C.J.; Wakeman, K.D.; Thomas, D.N.; Puhakka, J.A. url  doi
openurl 
  Title Eukaryotic and prokaryotic microbial communities during microalgal biomass production Type Journal Article
  Year 2012 Publication Bioresource Technology Abbreviated Journal Bioresour Technol  
  Volume 124 Issue Pages 387-393  
  Keywords Bacteria/classification/genetics/metabolism; *Biomass; Electrophoresis, Polyacrylamide Gel; Eukaryotic Cells; Microalgae/*metabolism; Phylogeny; Polymerase Chain Reaction; Prokaryotic Cells  
  Abstract Eukaryotic and bacterial communities were characterized and quantified in microalgal photobioreactor cultures of freshwater Chlorella vulgaris and marine Dunaliella tertiolecta. The microalgae exhibited good growth, whilst both cultures contained diverse bacterial communities. Both cultures included Proteobacteria and Bacteroidetes, while C. vulgaris cultures also contained Actinobacteria. The bacterial genera present in the cultures were different due to different growth medium salinities and possibly different extracellular products. Bacterial community profiles were relatively stable in D. tertiolecta cultures but not in C. vulgaris cultures likely due to presence of ciliates (Colpoda sp.) in the latter. The presence of ciliates did not, however, cause decrease in total number of C. vulgaris or bacteria during 14 days of cultivation. Quantitative PCR (qPCR) reliably showed relative microalgal and bacterial cell numbers in the batch cultures with stable microbial communities, but was not effective when bacterial communities varied. Raw culture samples were successfully used as qPCR templates.  
  Address (up) Department of Chemistry and Bioengineering, Tampere University of Technology, Tampere, Finland. aino-maija.lakaniemi@tut.fi  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0960-8524 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:22995170 Approved no  
  Call Number refbase @ user @ Serial 12987  
Permanent link to this record
 

 
Author Stedmon, C.A.; Thomas, D.N.; Granskog, M.; Kaartokallio, H.; Papadimitriou, S.; Kuosa, H. url  openurl
  Title Characteristics of dissolved organic matter in Baltic coastal sea ice: allochthonous or autochthonous origins? Type Journal Article
  Year 2007 Publication Environmental Science & Technology Abbreviated Journal Environ Sci Technol  
  Volume 41 Issue 21 Pages 7273-7279  
  Keywords Carbon/analysis; *Humic Substances; Ice Cover/*chemistry; Nitrogen/analysis; Oceans and Seas; Spectrometry, Fluorescence  
  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.  
  Address (up) Department of Marine Ecology, National Environmental Research Institute, University of Aarhus, Frederiksborgvej 399, 4000 Roskilde, Denmark. cst@dmu.dk  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0013-936X ISBN Medium  
  Area Expedition Conference  
  Notes PMID:18044499 Approved no  
  Call Number refbase @ user @ Serial 12979  
Permanent link to this record
Select All    Deselect All
 |   | 
Details

Save Citations:
Export Records: