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Author |
Thomas, D.N.; Kattner, G.; Engbrodt, R.; Giannelli, V.; Kennedy, H.; Haas, C.; Dieckmann, G.S. |
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Title |
Dissolved organic matter in Antarctic sea ice |
Type |
Journal Article |
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Year |
2001 |
Publication |
Annals of Glaciology |
Abbreviated Journal |
Ann Glaciol |
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Volume |
33 |
Issue |
1 |
Pages |
297-303 |
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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%. |
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International Glaciological Society |
Place of Publication |
Cambridge |
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Intl. Symp. on Sea Ice and its Interaction with the Ocean, A. and B., Fairbanks, Alaska(USA), 19-23 Jun 2000, |
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ISSN |
0260-3055 |
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no |
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Call Number |
refbase @ admin @ Thomas++2001 |
Serial |
761 |
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Author |
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 |
Type |
Journal Article |
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Year |
2001 |
Publication |
Polar Biology |
Abbreviated Journal |
Polar Biol |
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Volume |
24 |
Issue |
7 |
Pages |
486-496 |
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Abstract |
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 |
Place of Publication |
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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Volume |
15 |
Issue |
6 |
Pages |
447-483 |
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Keywords |
sea ice; Arctic; Dom |
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Abstract |
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 |
Place of Publication |
Heidelberg |
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0722-4060 |
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Notes |
D |
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no |
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Call Number |
refbase @ admin @ Thomas++1995 |
Serial |
763 |
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Author |
Thomas, D.N.; Lara, R.J.; Haas, C.; Schnack-Schiel, S.B.; Dieckmann, G.S.; Kattner, G.; Nöthig, E.-M.; Mizdalski, E. |
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Title |
Biological soup within decaying summer sea ice in the Amundsen Sea, Antarctica |
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Book Chapter |
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Year |
1998 |
Publication |
Antarctic sea ice: Biological processes, interactions and variability |
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Pages |
161-171 |
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Keywords |
Marine biology; Algae; Ice composition; Pack ice; Decomposition; Ecology; Nutrient cycle; Antarctica; Amundsen Sea |
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Abstract |
In late February 1994, during the ANT XI/3 expedition of R/V Polarstern, ice cores from perennial sea ice were sampled in the Amundsen Sea in areas of dense pack ice. The ice was largely rotten, and a conspicuous feature was the occurrence of thick gaps and voids, often filled with a dark brown slush comprised of loose ice chunks and crystals. These interior ice assemblages were at depths between 1.0 and 1.5 m in 3 to 4 m thick ice floes, and had remarkably rich interior ice algal assemblages (<= 377 µg Chl a L?¹) which were in turn a food source for unusually large numbers of foraminifers (<= 1262 individuals L?¹), the calanoid copepod Stephos longipes (<= 163 individuals L?¹) and harpacticoid copepods (<= 168 individuals L?¹). Analysis of inorganic nutrients (nitrate, phosphate, ammonium, nitrite, and silicate) and dissolved organic carbon (DOC) showed that these were sites of high nutrient supply coupled with high rates of nutrient regeneration. |
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American Geophysical Union |
Place of Publication |
Washington, DC |
Editor |
Lizotte, M.P.; Arrigo, K.R. |
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Antarctic Research Series |
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Series Volume |
73 |
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0-87590-901-9 |
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no |
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Call Number |
refbase @ admin @ Thomas++1998 |
Serial |
764 |
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Author |
Thomas, D.N.; Mock, T. |
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Title |
Life in frozen veins – coping with the cold |
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Journal Article |
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Year |
2005 |
Publication |
The Biochemist |
Abbreviated Journal |
Biochemist |
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Volume |
27 |
Issue |
1 |
Pages |
12-16 |
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Keywords |
adaptation; Antarctic; Arctic; low temperature; micro-organism; sea ice |
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Abstract |
Every autumn a fundamental transition occurs in the surface waters of Polar Oceans. The surface waters of millions of square kilometres freeze to form an ice layer that varies from a few centimetres through to several metres thick, and which effectively separates the ocean from the atmosphere above. Ice made from seawater is a porous, semi-solid matrix permeated by a labyrinth of brine channels and pores, and within these a diverse microbial assemblage, including viruses, archaea, bacteria, flagellates and unicellular algae can thrive. These assemblages can reach such high abundances that the ice becomes a rich coffee colour. The microbial assemblages are in turn a rich food source for grazing proto- and zooplankton, especially in winter when food in the water column is scarce. |
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Biochemical Society |
Place of Publication |
London |
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Call Number |
refbase @ admin @ Thomas+Mock2005 |
Serial |
765 |
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