Isotopic Study on Saline Lakes in Antarctica

Abstract

In order to understand the origin of saline lakes in the southern Victoria Land, Soya Coast, and Vestfold Hills, the hydrogen and oxygen isotopic ratios of lake waters were measured. The relationship between the two isotopic ratios in these lakes shifted from that of meteoric water in the direction of enrichment in ^O. This suggests that these lakes are in steady state balance with respect to mass and isotopic ratios between melt-water input and kinetic evaporation. In the southern Victoria Land, it is estimated that the inflow of melt water from glaciers might have begun at 5,800 years ago in the west lobe of Lake Bonney, 1,500 years ago in the east lobe of Lake Bonney, and 1,200 years ago in the Lake Vanda, respectively, on the basis of diffusion model for the mixing between the saline layer and the fresh water layer. The relationship of Na^+/Mg^ and Cl^-/Br^- to Cl^- content indicates that the salts in these lakes might have come from sea water, except for Lake Vanda and Don Juan Pond the compositions of which cannot be explained by the direct sea water origin.