A joint Russian-German expedition was carried out from July to September 1994 on the Taimyr Peninsula, Siberia. Hydrological, cryopedological and paleogeographical permafrost studies were undertaken by scientists of the Potsdam Research Department of the Alfred Wegener Institute for Polar and Marine Research (AWI), the Institute of Polar Ecology, Kiel (IPÖ) and the Institute of Soil Sciences, Hamburg University (HH) together with Russian counterparts. The investigations are part of an ongoing German- Russian project on the Late Quaternary environmental history of Central Siberia.
Hydrological studies were carried out in the Levinson-Lessing Lake catchment (Byrranga Mountains) by the AWI group in cooperation with scientists from the AARI (Arctic and Antarctic Research Institute), St. Petersburg. The objective is to trace seasonal water and solute transport in the active layer under a variety of geomorphological settings within the lake watershed underlain by continuous permafrost. The study focuses specifically on the determination of 1) flowpaths of water in the phreatic and vadose zone of the active layer and 2) sources and sinks of active layer water (precipitation, evaporation, frozen ground, lateral flow). During summer 1994, instruments were installed in the active layer to depths of maximum thaw. In-situ bulk electrical conductivity and volumetric moisture content of the active layer were measured using time domain reflectometry (TDR). Wells and piezometers were installed to determine water table elevations in the phreatic zone and to calculate hydraulic conductivities. The chemical and isotopical composition of water from the vadose and phreatic layer, precipitation, lake and stream water will be used to infer residence times, mixing rates, flowpaths and sources of water. Further field work is planned to start in May 1995 and continue until October to obtain data for one complete cycle of the active layer (thawing, maximum thaw depth, refreezing).
2. Paleogeographical studies of permafrost were carried out in the Labaz Lake area (Taimyr lowland) by scientists from the AWI, IPÖ, HH and the Department of Geocryology, Moscow State University. The main task of the field work was to study lithological and cryogenic structures of the perennially frozen sediments of the Labaz Lake drainage area using outcrops and core drilling. Samples of organic material were taken for C14-dating in various stratigraphic horizons. In peat and sediment profiles, samples were taken for palynological, lithological, stable isotopes (oxygen-18, deuterium) and tritium analysis of ground ice. The study was complemented by soil and microbiological investigations of recent tundra soils. These results will be used for reconstruction of the vegetation history, climatic conditions and character of sedimentary and cryogenic processes in the East of the Taimyr Lowland during the Late Quaternary period. In both areas measurement of the active layer depth related to the ITEX program was started (see Frozen Ground No. 16, p. 7, for data from the Taimyr sites).
At the AWI in Potsdam, Christine Siegert has started a research project on Frozen Geochemical Barrier (FGB): Its Dynamics and Influence on Substance Flux in Permafrost Landscapes. The project is in cooperation with Vladimir E. Ostroumov, Institute of Soil Sciences and Photosynthesis, and Bjarne Holm Jakobsen, Institute of Geography, University of Copenhagen. Integrated field work at different study sites and laboratory experiments is planned.
Geochemical processes in polar and subpolar regions are strongly influenced by the near-surface permafrost table. The boundary between the seasonally thawing soil and the perennially frozen gound is an important geochemical barrier. The thermodynamic conditions at the FGB determine phase transformations of water and the presence of ice. Extremely high gradients of chemical potentials are characteristic for this boundary. As a result, the intensity of chemical substance transformation and mass transfer increases. Specific geochemical processes developing at the FGB have a great influence on soil formation and other landscape forming processes in polar and subpolar terrestrial ecosystems. The character of geochemical processes at the FGB is determined by the interaction of climatic, biotic, geomorphological, geological and geocryological factors, which have varied over geological time.
The German working group on polar geography held its meeting in Jena (12-13 May). New results of the Geoscientific Spitzbergen Expeditions 1990/92 were presented. On 14 May the Quaternary geomorphology and chronology was discussed in the field on a full-day excursion to Bad Kösen and Weimar (led by R. Mäusbacher, Jena). The next working group meeting will be in Heidelberg on 10-11 November 1995.
Submitted by Lorenz King