AQUEOUS GEOCHEMISTRY OF MAJOR CONSTITUENTS IN THE ALPH RIVER AND TRIBUTARIES IN WALCOTT BAY, VICTORIA LAND, ANTARCTICA

Two geochemical surveys of the major constituents of the Alph River, situated in Walcott Bay, Victoria Land, were undertaken in the austral summer of 1987-88. At the same time, tributaries and the runoff from various glaciers were investigated. The Alph River has an average total dissolved solids (TDS) concentration of 63.5 mg l-1, approximately half that of average world river water. The chemical composition is dominated by Na+ and HCO3-. Glacial melt waters have very low TDS but chemical weathering over the course of a few kilometres causes solute concentrations in the tributaries to exceed those of the Alph River. The compositon of the streams is variable, but often Ca2+ is the principal cation. Enrichment factor and mass balance calculations indicate that the salts in the Alph River and its tributaries have a substantial non-marine component. Chemical weathering of calcite, mirabilite, gypsum and halite contribute solutes to the aquatic system. A "Gibbs Plot" [TDS versus Na:(Na+Ca) weight ratio] indicates that water samples from direct glacial runoff fall outside the world water envelope. They have low solute levels but enhanced Ca2+ concentrations, resulting from the aeolian deposition and subsequent dissolution of calcitic material.