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Schnack-Schiel, S.B.; Dieckmann, G.S.; Kattner, G.; Thomas, D.N. |
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Title |
Copepods in summer platelet ice in the eastern Weddell Sea, Antarctica |
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Journal Article |
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Year |
2004 |
Publication |
Polar Biology |
Abbreviated Journal |
Polar Biol |
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Volume |
27 |
Issue |
8 |
Pages |
502-506 |
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Abstract |
Copepods in platelet-ice layers underlying fast ice and in the water column below were studied at Drescher Inlet, eastern Weddell Sea in February 1998. Three copepod species were found: Drescheriella glacialis and Paralabidocera antarctica occurred in platelet-ice layers, while Stephos longipes was only present in the water column. The distribution of all species varied considerably between station and depth. D. glacialis dominated the platelet-ice community and occurred at all five platelet-ice sampling sites, except one, with numbers of up to 26 ind. l?¹. In contrast, P. antarctica was only found in low numbers (up to 2 ind. l?¹) at one site. The total copepod abundance in the platelet ice was not associated with algal biomass, although it was strongly correlated with high ammonium concentrations (up to 9 µM) in the interstitial water between the platelets. This is the first indirect evidence to support the hypothesis that zooplankton excretion can partly account for the high ammonium values often found in platelet-ice layers. |
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Springer-Verlag |
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Heidelberg |
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0722-4060 |
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Short note |
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no |
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Call Number |
refbase @ admin @ Schnack-Schiel++2004 |
Serial |
752 |
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Author |
Thomas, D.N.; Gleitz, M. |
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Title |
Allocation of photoassimilated carbon into major algal metabolite fractions: Variation between two diatom species isolated from the Weddell Sea (Antarctica) |
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Journal Article |
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Year |
1993 |
Publication |
Polar Biology |
Abbreviated Journal |
Polar Biol |
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Volume |
13 |
Issue |
4 |
Pages |
281-286 |
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Keywords |
carbon fixation; metabolites; biomass; Nitzschia curta; Chaetoceros; Psw; Weddell Sea |
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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. |
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Springer-Verlag |
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Heidelberg |
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0722-4060 |
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Bibliogr.: 48 ref.; Marine |
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Call Number |
refbase @ admin @ Thomas+Gleitz1993 |
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760 |
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Thomas, D.N.; Kennedy, H.; Kattner, G.; Gerdes, D.; Gough, C.; Dieckmann, G.S. |
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Title |
Biogeochemistry of platelet ice: its influence on particle flux under fast ice in the Weddell Sea, Antarctica |
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Journal Article |
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Year |
2001 |
Publication |
Polar Biology |
Abbreviated Journal |
Polar Biol |
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24 |
Issue |
7 |
Pages |
486-496 |
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An array of four sediment traps and one current meter was deployed under a well-developed platelet layer for 15 days in the Drescher Inlet in the Riiser Larsen ice shelf, in February 1998. Traps were deployed at 10 m (just under the platelet layer), 112 m (above the thermocline), 230 m (below thermocline) and 360 m (close to sea floor). There was a substantial flux of particulate organic material out of the platelet layer, although higher amounts were collected in the traps either side of the thermocline. Material collected was predominantly composed of faecal pellets containing diatom species growing within the platelet layer. The size classes of these pellets suggest they derive from protists grazing rather than from larger metazoans. Sediment trap material was analysed for particulate organic carbon/nitrogen/phosphorus (POC/PON/POP) and ?¹³CPOC (carbon isotopic composition of POC). These were compared with organic matter in the overlying platelet layer and the water column. In turn, the biogeochemistry of the platelet layer and water column was investigated and the organic matter characteristics related to inorganic nutrients (nitrate, nitrite, ammonium, silicate, phosphate), dissolved organic carbon/nitrogen (DOC/DON), pH, dissolved inorganic carbon (DIC), oxygen and ?¹³CDIC (carbon isotopic composition dissolved inorganic carbon). |
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Springer-Verlag |
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Heidelberg |
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0722-4060 |
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Call Number |
refbase @ admin @ Thomas++2001_2 |
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762 |
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Thomas, D.N.; Lara, R.J.; Eicken, H.; Kattner, G.; Skoog, A. |
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Title |
Dissolved organic matter in Arctic multi-year sea ice during winter: major components and relationship to ice characteristics |
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Journal Article |
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Year |
1995 |
Publication |
Polar Biology |
Abbreviated Journal |
Polar Biol |
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15 |
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6 |
Pages |
447-483 |
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Keywords |
sea ice; Arctic; Dom |
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Ice cores were collected between 10.03.93 and 15.03.93 along a 200 m profile on a large ice floe in Fram Strait. The ice was typical of Arctic multi-year ice, having a mean thickness along the profile of 2.56 ±0.53 m. It consisted mostly of columnar ice (83%) grown through congelation of seawater at the ice bottom, and the salinity profiles were characterized by a linear increase from 0 psu at the top to values ranging between 3 and 5 psu at depth. Distributions of dissolved organic carbon (DOC) and nitrogen (DON) and major nutrients were compared with ice texture, salinity and chlorophyll a. DOC, DON, dissolved inorganic nitrogen (DIN), NH?? and NO?? were present in concentrations in excess of that predicted by dilution curves derived from Arctic surface water values. Only NO?? was depleted, although not exhausted. High DOC and DON values in conjunction with high NH?? levels indicated that a significant proportion of the dissolved organic matter (DOM) was a result of decomposition/grazing of ice algae and/or detritus. The combination of high NH?? and NO?? points to regeneration of nitrogen compounds. There was no significant correlation between DOC and Chl a in contrast to DON, which had a positively significant correlation with both salinity and Chl a, and the distribution of DOM in the cores might best be described as a combination of both physical and biological processes. There was no correlation between DOC and DON suggesting an uncoupling of DOC and DON dynamics in multi year ice. |
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Springer-Verlag |
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Heidelberg |
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0722-4060 |
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D |
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Call Number |
refbase @ admin @ Thomas++1995 |
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763 |
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Author |
Carver, S.M.; Hulatt, C.J.; Thomas, D.N.; Tuovinen, O.H. |
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Title |
Thermophilic, anaerobic co-digestion of microalgal biomass and cellulose for H2 production |
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Journal Article |
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2011 |
Publication |
Biodegradation |
Abbreviated Journal |
Biodegradation |
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22 |
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4 |
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805-814 |
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Keywords |
Anaerobiosis; Biodegradation, Environmental; Biofuels; Biomass; Bioreactors; Cellulose/*metabolism; Chlorella vulgaris/*metabolism/microbiology; Chromatography, High Pressure Liquid; Fatty Acids, Volatile/biosynthesis; *Fermentation; *Hydrogen/metabolism; Microalgae/*metabolism/microbiology; Microbial Consortia |
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Microalgal biomass has been a focus in the sustainable energy field, especially biodiesel production. The purpose of this study was to assess the feasibility of treating microalgal biomass and cellulose by anaerobic digestion for H2 production. A microbial consortium, TC60, known to degrade cellulose and other plant polymers, was enriched on a mixture of cellulose and green microalgal biomass of Dunaliella tertiolecta, a marine species, or Chlorella vulgaris, a freshwater species. After five enrichment steps at 60 degrees C, hydrogen yields increased at least 10% under all conditions. Anaerobic digestion of D. tertiolecta and cellulose by TC60 produced 7.7 mmol H2/g volatile solids (VS) which were higher than the levels (2.9-4.2 mmol/g VS) obtained with cellulose and C. vulgaris biomass. Both microalgal slurries contained satellite prokaryotes. The C. vulgaris slurry, without TC60 inoculation, generated H2 levels on par with that of TC60 on cellulose alone. The biomass-fed anaerobic digestion resulted in large shifts in short chain fatty acid concentrations and increased ammonium levels. Growth and H2 production increased when TC60 was grown on a combination of D. tertiolecta and cellulose due to nutrients released from algal cells via lysis. The results indicated that satellite heterotrophs from C. vulgaris produced H2 but the Chlorella biomass was not substantially degraded by TC60. To date, this is the first study to examine H2 production by anaerobic digestion of microalgal biomass. The results indicate that H2 production is feasible but higher yields could be achieved by optimization of the bioprocess conditions including biomass pretreatment. |
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Department of Microbiology, Ohio State University, 484 W. 12th Ave., Columbus, OH 43210, USA. carver.84@gmail.com |
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English |
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0923-9820 |
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PMID:20878208 |
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refbase @ user @ |
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12982 |
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