ANTARCTIC SALINE LAKES - STABLE ISOTOPIC RATIOS, CHEMICAL COMPOSITIONS AND EVOLUTION

About 90 saline and fresh water lakes as well as glaciers and their melt waters from the ice-free areas of the Soya Coast, the Vestfold Hills and the Southern Victoria Land of Antarctica have been analyzed for hydrogen and oxygen isotopic ratios. These results and the chemical compositions so far published indicate four types of saline lakes. 1. (1) Three saline lakes on the beaches of the first two areas which still are receiving sea water as the major inflow. 2. (2) Other lakes of these two areas which are isolated from sea water inflow. The isotopic ratios of their waters are higher and are plotted farther to the right of the meteoric water line, on the δD vs δ18O diagram, with increasing salinity. This is because the higher the salinity of a lake, the lake is ice free for a longer period of year, and thus the lake water is more significantly affected by the isotopic effect of evaporation from liquid water. 3. (3) Lake Bonney in the Taylor Valley of the Southern Victoria Land. The west and east lobes of this lake chemically are stratified but only the east lobe shows stratification in the isotopic ratios. Both lobes started as shallow saline lakes similar to some of the saline lakes classified in (2). Fresh water flooding into the lakes and subsequent diffusion mixing formed the present features. By solving diffusion equations under certain assumptions the evolutionary history of Lake Bonney was modeled. 4. (4) Lake Vanda and Don Juan Pond in the Wright Valley of the Southern Victoria Land. Lake Vanda is strongly stratified in both the salinity and isotopic ratios and seems to have a similar evolution history to east lobe of Lake Bonney. Chemical composition of the lakes in (2) and (3) differs variously from that of sea water but can be interpreted by different degrees of low temperature concentration of sea water by evaporation or freeze-drying. On the other hand, the high concentration of Ca2+ relative to Mg2+ and Na+ in the lakes of the Wright Valley cannot be interpreted by this way. © 1979.