OXYGEN STABLE ISOTOPES AND CHLORIDE CONCENTRATION IN THE SURFACE WATERS OF TAYLOR VALLEY LAKES, ANTARCTICA, DURING THE PAST 40 YEARS
For this study oxygen isotope and chloride data for the several meters of water below the ice on each lake are compiled. These data include depth profiles from: Lake Bonney lobes and Lake Fryxell from summer 1972, Lake Fryxell from summer 1991, Lake Hoare from summer 1994, all three lakes from summer 2002, Lake Hoare from summer 2005, and all three lakes from January 2012. The oxygen stable isotope composition of the three lakes differ by lake due to in-stream fractionation within each basin (i.e., enrichment by evaporation) and the glacial source water isotopic signature (i.e., isotopically lighter glacial melt water further inland from Ross Sea and/or from different source areas within a glacier). During the last forty years, the surface waters of the Taylor Valley lakes have become isotopically lighter but the chloride concentration has not decreased from dilution as a result of the drastically increased water levels. In this presentation we address how stream flow during a season influences isotopic and element composition of these lakes, and how the isotopic time series is a response to changing climates and melt regimes.