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A 270 cm long sediment sequence was recovered with a piston corer from east lobe Bonney, Taylor Valley, Antarctica, and characterized according to its sedimentological, mineralogical, and geochemical properties. It is the first record of such length recovered from east lobe Bonney. The sediment core is mainly composed of halite crystals of different sizes, water, and a relatively low and stable proportion of clastic particles. Although the sediment surface was probably disturbed by the coring process and absence or low contents of organic material or carbonates hampers the establishment of a robust chronology by radiocarbon dating, the core probably contains at least several hundred years of information about the history of the lake and the Bonney basin. Variations in halite crystal sizes and amount as well as variations in the composition of clastic material can be related to past lake level changes and evaporation cycles. [ABSTRACT FROM AUTHOR]

Abstract: We investigated the vertical structure of physicochemical properties in 27 lakes at Skarvsnes and Langhovde, Syowa Oasis, East Antarctica, from December 2003 to February 2004. The lakes were classified into three types based on their origin and geographical characteristics: non-marine relic lakes, marine relic and lotic lakes, and marine relic and lentic lakes. We describe the physicochemical characteristics of each lake type. When the non-marine relic lakes were partly covered with ice, the water column was stratified beneath the ice. In the non-marine relic lakes, during the season with no ice cover, physicochemical parameters were uniform throughout the water column, probably due to frequent vertical mixing induced by wind force and thermal convection within the shallow basins. Similarly, in marine relic and lotic lakes, lake waters appeared to be completely mixed because of a large inflow of meltwater from glaciers and outflow to other lakes and the coastal sea. In the marine relic and lentic lakes, except for Lake Himebati-ike, the lake water was vertically stratified with a strong halocline. In Lakes Suribati-ike and Hunazoko-ike, salinity was very high (up to 20%) due to evapoconcentration. Lake Suribati-ike is a meromictic lake, with a monimolimnion developed below 10m water depth. [Copyright &y& Elsevier]