Physical structure of epishelf lakes of the southern Bunger Hills, East Antarctica

Epishelf lakes, positioned between ice-free areas and floating ice shelves or glaciers, are unusual tidal, but largely freshwater, environments found in both the Arctic and the Antarctic. The greatest concentration of these lakes is in the Bunger Hills, East Antarctica (66degreesS, 100degreesE). We present and discuss temperature and salinity profiles for five epishelf lakes from this region, most of which show unusual properties. White Smoke Lake is fresh and cold (<0.1degreesC) throughout; Lake Pol'anskogo has two basins, one fresh and cold, the other saline and warm; 'Southern' Lake is cold and saline at depth; Transkriptsii Gulf has a deep, warm saline layer; and 'Northern' Lake is relatively warm throughout. The structures of these lakes can be explained in terms of a simple model in which the isolated saline water evident in three of the lakes entered the basins through the connection to the marine waters during periods of reduced freshwater input. By dating these marine incursions, periods of reduced melt, presumably due to colder temperatures, can be determined.