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«Changing Polar Regions 25th International Congress on Polar Research March 17-22, 2013, Hamburg, Germany German Society for Polar Research Edited by ...»

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Dissolved inorganic nitrogen (DIN, ammonia, nitrite and nitrate) were analyzed as an indicator for N-limitation in different soils over the vegetation period and additionally potential nitrification and N-mineralization rates were determined for giving insight into the ongoing N-cycle in the investigation sites.

Different permafrost soils on Samoylov Island in the Lena river delta were analyzed:

Polygonal tundra (Typic Aquiturbel and Typic Historthel) was characterized as water saturated organic rich soils with high C/N ratios and slightly acid pH values. The dry sandy soils of the floodplain areas (Typic Psammenorthel and Psammentic Aquorthel) were characterized by neutral pH value, a high mineral content and low water content.

DIN was generally detected in small amounts. In the water saturated polygons ammonium was present in all samples and the main element of DIN, nitrate wasn´t detectable: so the polygonal tundra can be characterized as nitrogen limited. At the soils of the beach without vegetation nitrate was enriched by the end of the vegetation period. In the sandy, but organic matter rich layers of the beach and cliff, remineralized ammonium was detectable but decreasing during the vegetation period. Nitrite was in general present in trace amounts. In soil samples ofthe floodplain areas higher nitrification potentials were measured than in the water saturated peaty soils of the polygonal tundra. The potential nitrification and Nmineralization rates were in comparison to soils in moderate climate very low.

In Samoylov Island the soils of the polygonal tundra are N-limited; in the sandy soils of floodplain required N species are available. They are provided by the slowly occurring but important process of nitrification.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 CAVE.LIFE: SCHOOLS WORKING ON LAMPENFLORA IN AN

ENGLACIAL SYSTEM (HINTERTUXER EISPALAST)

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Bridging schools and science is sometimes a hard nut to crack. However, the program Sparkling Science (based in Austria) offers best conditions for establishing those contacts. The scope of CAVELIFE is the investigation of ice caves as a glacial refugium for microbes. In order to sustain reproduction and metabolism the living communities in this harsh environment must adapt to extreme conditions such as low temperatures, low nutrient concentrations and very limited availability of liquid water.

So far, knowledge about the microbial loop in ice ecosystems such as ice caves with its various compartments (ice, melt water, sediment and ambient air) is scarce.

Moreover, most of these caves in Central Europe are subject to touristic usage which most likely provokes an impact on the original composition of the cave flora and fauna. To assess the ecological potential of those ice caves in term of biomass and metabolism (respiration, carbon production) we intend to conduct a serious of studies together with various schools from Austria and the US. Additional experiments will be subject to study the consequences of anthropogenic impact. Since ice caves are ultra-oligotrophic habitats, hence there is a specific need for the application of noninvasive techniques to detect biosignatures. With a laser application which is able to detect photosynthetic active pigments, amino and nucleic acids in ice, respectively, we intent to establish a non-invasive mode to be able to detect these molecules via a rover even in niches of the ice caves with limited access. Furthermore, the scanning mode of the laser with various applications could improve the resolution of data points substantially when compared to traditional coring and sampling. Together with schools of Innsbruck and the US we plan to describe biological communities with this modular laser system of which a portable prototype already exists. These future investigations should shade light on so far neglected ecosystems which are extremely sensitive to slight temperature changes.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 L.I.F.E. (LASER INDUCED FLUORESCENCE EMISSION) AS NONINVASIVE TOOL TO ASSESS PHOTOSYNTHETIC PIGMENTS IN ICE

ECOSYSTEMS

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Laser-induced fluorescence emission (L.I.F.E.) is an in situ laser scanning technique to detect photoautotrophic pigments such as phycoerythrin of an ice ecosystem without invasion. The sensitivity of many psychrophiles to even moderate changes in temperature, and the logistical difficulties associated with either in situ analysis or sampling makes it difficult to study microbial metabolism in ice ecosystems in a high resolution. In general, the ice habitat has to be disrupted using techniques that usually include coring, sawing and melting. Samples are also often chosen blindly, with little indication of probable biomass. The need for an in situ non-invasive, nondestructive technique to detect, localize, and sample cryosphere biomass in the field is therefore of considerable importance.

Surface communities of cold ecosystems are highly autotrophic and therefore ideal systems for L.I.F.E examinations. 532nm green lasers excite photopigments in cyanobacteria and produce multiple fluorescence signatures between 550nm and 750nm including carotenoids, phycobiliproteins which would enable a non-invasive in-situ measurement.





L.I.F.E has already been tested in remote ecosystems like Lake Untersee and Lake Fryxell (Antarctica) as well as High Arctic and Alpine glaciers, but until now no calibration was set to convert the L.I.F.E. signal into pigment concentration. Here we describe the standardization for detection of phycobiliproteins (phycoerythrine) which are found in red algae, cyanobacteria, and cryptomonads. We could relate different concentrations of phycoerythrine and also chlorophylla with a corresponding fluorescence signal. Furthermore the dependency of the L.I.F.E. signal with the depth of phycoerythrine in the ice, as well as with the concentration of sediments was analysed.

Similar methods are already used for detection of phytoplankton in liquid systems like oceans and lakes by NASA´s Airborne Oceanographic LIDAR since 1979. The possibility to use L.I.F.E. in ice ecosystems though is a novelty.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 ANWENDUNG DER SATELLITEN- UND FLUGGRAVIMETRIE FÜR

DIE SCHWEREFELDBESTIMMUNG IN DER ANTARKTIS

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Die Bestimmung des äußeren Schwerefelds der Erde ist ein Hauptaufgabe der Geodäsie. In vielen Problemstellungen -- und nicht nur in der Geodäsie -- spielen schwerefeldbezogene Größen eine wichtige Rolle. So ist das Geoid eine beste Approximation der Figur der Erde und Referenzfläche für Höhensysteme. In der Ozeanographie ist die mittlere Meeresoberflächentopographie auf das Geoid bezogen. In einer glaziologischen Anwendung wird mit Hilfe von Freibordhöhen und Dichteannahmen sowie des Geoids die Dicke von Schelfeisen abgeleitet. Globale, die längeren Wellenlängen des Schwerefelds erfassende Modelle beruhen im Wesentlichen auf Satellitenmessungen, während für höher auflösende Modelle global verteilte, terrestrische Daten hinzugefügt werden müssen. Beide Messmethoden haben in der Antarktis ihre Vor- und Nachteile. Insbesondere entsteht aufgrund der nicht exakt polaren Bahnen der dedizierten Schwerefeldsatelliten eine polare Datenlücke. Terrestrische Daten sind -- aufgrund der bekannten Bedingungen in der Antarktis -- kontinental nicht mit der notwendigen Dichte durch Bodenmessungen erfassbar. Hier stellt einzig die Fluggravimetrie eine leistungsfähige Methode zur oberflächennahen Messung von Schweredaten zur Verfügung.

In der Präsentation wird auf die Methoden der Satelliten- und Fluggravimetrie eingegangen. Die aktuellen Modelle, die insbesondere Daten der Schwerefeldmission GOCE benutzen, werden in Hinblick auf ihre Auflösung und Genauigkeit in der Antarktis untersucht. Aktuelle und geplante gravimetrische Befliegungen, die durch verschiedene polarforschende Institutionen -- unter anderem das AWI -- durchgeführt werden, werden diskutiert. Soweit möglich, werden solche Schweredaten im Rahmen der Subcommission 2.4f "Gravity and Geoid in Antarctica" der Internationalen Assoziation für Geodäsie (IAG) gesammelt und für die regionale Schwerefeldverbesserung genutzt. Schließlich soll ein sich in Planung befindliches Projekt vorgestellt werden, bei dem das neue deutsche Forschungsflugzeug HALO für eine gravimetrische Befliegung in der Antarktis genutzt werden soll. Erste Erfahrungen konnten mit diesem Flugzeug durch die Realisierung der GEOHALOMisison (Juni 2012) gesammelt werden. Schließlich werden Anwendungen in der Geodäsie und Nachbardisziplinen vorgestellt.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 A UNIQUE FINE-GRAINED SEDIMENT LAYER DEPOSITED WEST

OFF SVALBARD DURING THE INITIAL WARMING AFTER THE LAST

GLACIAL MAXIMUM (BØLLING/ALLERØD)

Kevin Schiele1; H. Christian 1 Alfred-Wegener-Institut HelmholtzHass1, Matthias Forwick2 Zentrum für Polar- und Meeresforschung, Wadden Sea Research Station, List, Germany University of Tromsø, Department of Geology, Tromsø, Norway The study aims to elucidate the processes that caused the deposition of a unique fine-grained sediment layer at the onset of the last deglacial basically along the western Svalbard margin and the western Yermak Plateau. Grain-size analyses of 11 sediment cores west and north off Svalbard and the Yermak Plateau reveal an exceptionally fine-grained sediment layer that was deposited within a relatively short period of ~300 years during the Bølling interstadial. The layer was found in cores located below the West Spitsbergen Current (WSC) that conveys Atlantic (AW) and mixed water masses northwards along the continental slope. The mixed waters are underlain by Norwegian Sea Deep Water (NSDW, water depth 1000 m). North of Svalbard the upper 500 m (sill depth) branch off and flow in easterly direction to form the Svalbard Branch of the WSC. Further north the Yermak Slope Current (YSC, water depth: 1000 to 1500 m) advects NSDW towards the Arctic Ocean where it quickly loses its signature north of the Yermak Plateau. The studied fine-grained layer reveals a sortable-silt mean grain size of 15 to 20 µm. The fineness of this layer is basically the result of a coarse-silt subpopulation between 36 and 63 µm that is absent in this layer but present throughout most of the cores. As yet the sediment layer was found in 32 sediment cores (mostly published data) from ~75°N to ~82°N at water depths ranging from ~300 m (Kveithola) to 1880 m (Yermak slope) south, west and north of Svalbard. Very low magnetic susceptibility, a distinct decrease in Caratios and slightly increased Ti-ratios are further key characteristics for the investigated layer (XRF analyses of 4 cores). AMS age determinations of another 4 cores show a doubled to ten-fold increased sedimentation rate for the period of deposition of this layer. The greatest thickness of the fine-grained layer appears in sediment cores from ~1400 to ~1500 m water depth and decreases in cores deeper than ~1600 m and cores shallower than ~1100 m water depth (except for Kveithola), respectively. Thus, the fine-grained material was transported northwards in a relatively narrow strip along the western Svalbard and Yermak slopes. The distribution and thickness of the investigated sediment layer can be linked to both, the rapid melting of the Svalbard and the Barents Sea ice sheets in response to the intense warming at the onset of the Bølling period. Since Kveithola trough is assumed to be fully deglaciated since 14.7 cal. years BP a sediment source in the adjacent Barents Sea as well as from local fjords of Spitsbergen is likely.

Reference for the oceanographic information: Schlichtholz and Houssais, 1999.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 D-MODELLIERUNG VON SCHWERE- UND MAGNETFELD-DATEN

IN NORD-VIKTORIALAND (ANTARKTIS): NEUE ERKENNTNISSE

ÜBER DAS AUSEINANDERBRECHEN GONDWANAS

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Auf der Basis verschiedener geophysikalischer Daten ist es möglich, die Struktur des Untergrunds auf verschiedensten Skalen zu untersuchen. Ein Beispiel hierfür ist die 3D-Modellierung von Schwerefeld-daten. In Nord-Viktorialand (Antarktis) sind gravimetrische Daten aus verschiedenen Quellen verfüg-bar (terrestrisch, Schiffsgravimetrie, Satellitendaten), die zur Modellierung mit dem Programm IGMAS+ genutzt werden können. Dieses Programm bietet die Möglichkeit, gemeinsam mit gravimetrischen Daten auch Magnetfelddaten zu modellieren; die entsprechenden Daten sind aus aeromagnetischen Messungen vorhanden.

Ziel der Modellierung ist es, einen Beitrag zur Klärung der Entwicklungsgeschichte der Region zu lie-fern, insbesondere hinsichtlich des Auseinanderbrechens des Großkontinents Gondwana. Erweiterte Erkenntnisse zur Struktur der Kruste können dazu Anhaltspunkte liefern.

Nach der Zusammenstellung und einer ersten Evaluierung der Daten ist es möglich, Modelle zu entwickeln, die, ausgehend von allen bekannten geologischen und geophysikalischen Informationen (z.B. geologische Grenzen, Störungen, Dichten und krusteninterne Strukturen), für einzelne Bereiche der Region die geophysikalischen Anomaliefelder bestmöglich erklären.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 FOSSIL ORGANIC MATTER IN ARCTIC PERMAFROST

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