Geomorphological Insight of Some Ice Free Areas of Eastern Antarctica

The Schirmacher Oasis and Larsemann Hills are among the few significant ice free areas of East Antarctica that are conspicuous due to presence of more than a hundred melt water lakes each, preserving the signatures of climatic variation and deglaciation history since Last Glacial Maximum (19 to 24 ky BP) and beyond. There are evidences, recorded in the lake sediments of low lying Larsemann Hills, of marine transgression due to variation in sea level, isostatic upliftment and close vicinity of the Hills to the marine environment. The Schirmacher Oasis, on the other hand has preserved various landforms-both erosional and depositional- typical of a periglacial environment along with proglacial lakes (incorporating signals of ice-sheet dynamics) and epishelf lakes (signatures of marine influence)

Filamentous Soil Fungi from Ny-Ålesund, Spitsbergen, and Screening for Extracellular Enzymes

Soil filamentous fungi from Ny-Ålesund, Spitsbergen, were studied. A total of 30 fungal isolates were identified by morpho-taxonomy, and the identity of some morpho-taxonomically complex isolates was authenticated by ITS1-5.8S and ITS2 rDNA domain sequence similarity. The isolates belonged to 19 species under 14 genera (Acremonium, Arthrinium, Aspergillus, Cladosporium, Corynespora, Emericella, Geomyces, Mortierella, Mucor, Myrothecium, Penicillium, Phialophora, Preussia, Xylaria). To the best of our knowledge, Acremonium roseolum, Aspergillus aculeatus, Emericella nidulans, and Preussia sp. are the first northernmost records from Arctic soils. The viable fungal count in different soil samples varied from 0.5 • 104 to 2.0 • 105 g-1. Species richness in different soil samples was also calculated. Mortierella was one of the most dominant genera in Arctic soils. A temperature tolerance study was carried out for all the isolates, and representative species were screened for their extracellular enzyme activity (amylase, cellulase, phosphatase, and pectinase) at 4˚C and 20˚C. Among the 30 isolates, seven showed cellulolytic activity, two were phosphate solubilizers, three had amylolytic activity, and only one showed pectinolytic activity on solid media. CMCase (β1, 4-endoglucanase) activity was quantified in seven isolates that exhibited positive activity during preliminary screening. The records of enzyme activity for amylases, pectinases, and cellulases are the first from the fungi of Spitsbergen. The present study indicates the dominance in Ny-Ålesund of cellulolytic strains, which may serve as potent decomposers in Arctic tundra. These isolates may be used to facilitate the mineralization of cellulolytic wastes generated by human activities in colder hilly areas across the world, including the Himalayas in India.Nous avons étudié des champignons telluriques filamenteux de Ny-Ålesund, Spitzberg. Grâce à la morpho-taxonomie, nous avons identifié 30 isolats fongiques, et l’identité de certains complexes d’isolats morpho-taxonomiques a été authentifiée au moyen des similarités des séquences de domaines ITS1-5.8S et ITS2 DNAr. Les isolats relevaient de 19 espèces faisant partie de 14 genres (Acremonium, Arthrinium, Aspergillus, Cladosporium, Corynespora, Emericella, Geomyces, Mortierella, Mucor, Myrothecium, Penicillium, Phialophora, Preussia, Xylaria). Au meilleur de nos connais­sances, Acremonium roseolum, Aspergillus aculeatus, Emericella nidulans et Preussia sp. constituent les premiers enregis­trements aussi nordiques des sols arctiques. Le dénombrement viable de champignons dans différents échantillons de sol variait de 0,5 • 104 à 2,0 • 105 g-1. Nous avons également calculé la diversité des espèces prélevées dans différents échantillons de sol. Le genre Mortierella était l’un des plus dominants des sols arctiques. Nous avons étudié la tolérance à la température de tous les isolats, et des espèces représentatives ont été examinées du point de vue de l’activité enzymatique extracellulaire (amylase, cellulase, phosphatase et pectinase) à 4 ˚C et 20 ˚C. Parmi les 30 isolats, sept présentaient de l’activité cellulolytique, deux étaient des solubilisants du phosphate, trois présentaient de l’activité amylolytique et seulement un présentait de l’activité pectolytique dans le cas des solides. L’activité CMCase (β1, 4-endoglucanase) a été quantifiée dans sept isolats qui affichaient une activité positive au cours de l’examen préliminaire. Il s’agissait de la première fois que de l’activité enzymatique pour les amylases, pectinases et cellulases a été détectée dans les champignons de Spitzberg. Cette étude indique la dominance de souches cellulolytiques à Ny-Ålesund, souches qui peuvent servir de décomposeurs puissants dans la toundra arctique. Ces isolats peuvent servir à faciliter la minéralisation des déchets cellulolytiques émanant des activités humaines dans les régions montagneuses plus froides du monde entier, y compris l’Himalaya, en Inde

QuikSCAT-based momentum flux analysis over the Southern Ocean

47-54Using QuikSCAT vector winds, the seasonal and interannual variability of momentum flux were studied to explore the underlining dynamics for its modulation over the Southern Ocean (SO) during August 1999 to July 2003. The wind speed validation of ship and QuikSCAT measurements in the western Indian sector of the SO showed a bias and root mean square error of 0.3 and 1.6 m/s, respectively. On seasonal time scales, the spatial wind stress patterns reveal a basin-wide variability and the boreal summer monsoon significantly influencing it in the Indian Ocean (IO) sector. The temporal march of the momentum flux for different ocean sectors exhibit a seasonal cycle with a maximum range between 0.13 and 0.18 N/m2 during August-September and a minimum range between 0.07 and 0.11 N/m2 during December – January, with a temporal shift of ±1 month between the sectors. The atmospheric pressure gradient between tropics and high latitudes enhances the momentum flux in the IO sector during austral winter. On interannual time scales the momentum flux maps indicate a marked regional variability which is highest in IO sector and an evolution of cyclonic circulation south of 50°S during austral winter. Based on earlier studies and after a detailed examination of SST and wind stress curl fields, it is argued that orientation of the SST gradient relative to direction of wind stress drive an atmospheric response through wind stress curl and divergence modulations, which in turn dictates the intensity of momentum flux on seasonal time scales

Earth System Processes and Disaster Management

XII, 244 p. 119 illus., 92 illus. in color.onlin

Mineral analysis and geochemistry of Muehlig-Hofmannfjella granitoids, Central Drooning Maud Land, East Antarctica

Ferrosilite-fayalite bearing charnockite and biotite-hornblende bearing granite are exposed in Mühling-Hofmannfjella, central Dronning Maud Land of East Antarctica. Both are interpreted as essentially parts of a single pluton in spite of their contrasting mineral assemblages. Based on petrologic and geochemical studies, it is proposed that H2O-undersaturated parent magma with igneous crustal component that fractionated under different oxygen fugacity conditions resulted in the Mühlig-Hofmannfjella granitoids