Soil characteristics and abundance of archaea in samples from the Ross Sea Region, Antarctica

The objective of this study was to examine the presence and diversity of Archaea within mineral and ornithogenic soils from 12 locations across the Ross Sea region. Archaea were not abundant but DNA sufficient for producing 16S rRNA gene clone libraries was extracted from 18 of 51 soil samples, from four locations. A total of 1452 clones were analysed by restriction fragment length polymorphism and assigned to 43 operational taxonomic units from which representatives were sequenced. Archaea were primarily restricted to coastal mineral soils which showed a predominance of Crenarchaeota belonging to group 1.1b (>99% of clones). These clones were assigned to six clusters (A through F), based on shared identity to sequences in the GenBank database. Ordination indicated that soil chemistry and water content determined archaeal community structure. This is the first comprehensive study of the archaeal community in Antarctic soils and as such provides a reference point for further investigation of microbial function in this environment.

Granulometry, biogenic silica content, magnetic susceptibility and bulk densities of ODP Site 188-1165

The Prydz Bay area is a key region for studying and understanding the history of the eastern Antarctic Continental Ice Sheet (O'Brien, Cooper, Richter, et al., 2001, doi:10.2973/odp.proc.ir.188.2001). Ocean Drilling Program (ODP) Site 1165 is situated in a water depth of 3357 m on the continental rise offshore from Prydz Bay and lies in front of the outlet for the Lambert Glacier-Amery Ice Shelf system that today drains 22% of East Antarctica. The site was drilled into mixed pelagic and hemipelagic sediments from the southwestern side of the Wild Drift. The drift is an elongate sediment body formed by the interaction of sediment supplied from continental shelf and slope with westward-flowing bottom currents. The sedimentary sequence is characterized by alternations between a generally gray to dark gray facies and a green to greenish gray facies. The greenish facies are structureless diatom-bearing clays with common bioturbation and larger amounts (>15%-20%) of biogenic silica, dispersed clasts, and lonestones than the dark gray facies, which are mostly less bioturbated clay with some silt laminations (Shipboard Scientific Party, 2001, doi:10.2973/odp.proc.ir.188.103.2001). High-quality advanced piston corer and extended core barrel cores containing nearly complete sections of middle Miocene to early Pliocene age allow a detailed characterization of sedimentary cycles and can provide indications for ice advances of the Lambert Glacier system into Prydz Bay, for the extent of sea ice, and for changes in oceanic circulation. The purpose of this work is to provide a data set of coarse-fraction mass percentage (>63, >125, and >250 µm) and biogenic silica content measured on sediments of late Miocene to early Pliocene age drilled at Site 1165. Additionally, high-resolution records of magnetic susceptibility (MS) and gamma ray attenuation (GRA) bulk density are presented. These shipboard data sets were edited postcruise. Furthermore, I provide a high-resolution dry bulk density record that is derived from GRA bulk density and can be used for the calculation of mass accumulation rates. These sedimentological and physical parameters will be used in future work to understand the depositional pattern of alternating biogenic and terrigenous sediments that was observed at Site 1165 (Shipboard Scientific Party, 2001, doi:10.2973/odp.proc.ir.188.103.2001).

Surface water properties, phytoplankton composition and photosynthesis rates of Amundsen Sea sites

The phytoplankton community composition and productivity in waters of the Amundsen Sea and surrounding sea ice zone were characterized with respect to iron (Fe) input from melting glaciers. High Fe input from glaciers such as the Pine Island Glacier, and the Dotson and Crosson ice shelves resulted in dense phytoplankton blooms in surface waters of Pine Island Bay, Pine Island Polynya, and Amundsen Polynya. Phytoplankton biomass distribution was the opposite of the distribution of dissolved Fe (DFe), confirming the uptake of glacial DFe in surface waters by phytoplankton. Phytoplankton biomass in the polynyas ranged from 0.6 to 14 µg Chl a / L, with lower biomass at glacier sites where strong upwelling of Modified Circumpolar Deep Water from beneath glacier tongues was observed. Phytoplankton blooms in the polynyas were dominated by the haptophyte Phaeocystis antarctica, whereas the phytoplankton community in the sea ice zone was a mix of P. antarctica and diatoms, resembling the species distribution in the Ross Sea. Water column productivity based on photosynthesis versus irradiance characteristics averaged 3.00 g C /m**2/d in polynya sites, which was approximately twice as high as in the sea ice zone. The highest water column productivity was observed in the Pine Island Polynya, where both thermally and salinity stratified waters resulted in a shallow surface mixed layer with high phytoplankton biomass. In contrast, new production based on NO3 uptake was similar between different polynya sites, where a deeper UML in the weakly, thermally stratified Pine Island Bay resulted in deeper NO3 removal, thereby offsetting the lower productivity at the surface. These are the first in situ observations that confirm satellite observations of high phytoplankton biomass and productivity in the Amundsen Sea. Moreover, the high phytoplankton productivity as a result of glacial input of DFe is the first evidence that melting glaciers have the potential to increase phytoplankton productivity and thereby CO2 uptake, resulting in a small negative feedback to anthropogenic CO2 emissions.

Documentation of Vernagtferner from the 17th century

Five paintings and sketches of the advances of the Vernagtferner in the 17th century are presented, four of which have recently been re-discovered in the Tyrolean archives. The view of the glacier in the year 1601 is the oldest known picture of an alpine glacier up to now. The pictures are discussed together with the written informations with regard to the extent of the glacier advances and the out bursts of the ice dammed lakes.

Verlauf der Ausaperung des Stubacher Sonnblickkees im Haushaltsjahr 1989/90

By making the photogrammetric monoplotting-procedure operational, this new method is now applicable for the documentation of glacial snow depletion. In a time series taken in summer 1990 monoplotting was the first time used for terrestrial survey of a glacier. The monoplotting-procedure, the terrestrial photodocumentation and the geodetic evaluation are described. The results from the Stubacher Sonnblickkees are presented in tabular form as well as in a series of thematic maps. A comparison of monoplotting and aerophotogrammetric survey confirms the suitability of the monoplotting-procedure for the mapping of glacial snow depletion.

Radionuclides in ice cores I and II from Vernagferner, Austria

Fission product (90Sr-90Y, 137Cs, total beta) and 21OPb-210Po activities were measured in core samples from the temperate vernagtferner (3150 m altitude, Oetztal Alps, Austria). The results show that the investigated fission products are transported with water resulting from melting processes, and are sorbed on dust or dirt horizons. These products are, therefore, not suited for dating temperate glaciers. 210Pb is also transported with water and displaced from its original deposition. However, despite large fluctuations, the specific activity of 210Pb decreases with depth, and can be used to estimate accumulation rates and the age of the ice. The average annual accumulation rate amounts to about 80 cm water equivalent, and the deepest sample (81 m i.e. ab. 65 m w. e.) was deposited in the beginning of this century. These results agree with data obtained from other observations on this glacier and show that the 210Pb_method is suitable to date temperate glaciers, if the ice cores cover a time interval of about 100 years (i.e. ab. 4 half-lives of 210Pb). The surface activity of 210Pb was found to be 5 ± 1 dpm per kg of ice in agreement with other locations in the Alps and with measurements of fresh snow.