Changes of major ion concentrations in melting snow and terrestrial waters from northern Victoria Land, Antarctica

Abstract

Concentrations of major ions (Cl⁻, NO₃⁻, SO₄²⁻, Na⁺, K⁺, Mg²⁺, Ca²⁺) were measured in melting snow and water samples from streams and lakes in ice-free areas throughout northern Victoria Land. Most ions in snow and terrestrial water derive from the marine environment and their concentrations are extremely variable in space and time, especially in water systems without melting snow and ice. The distance from the sea, snow sublimation, changes in water inflow, evaporative concentrations, weathering and drainage processes in the catchment, nesting seabirds and aquatic microbiota are among factors which most influence ion composition variability. Comparisons with data from twelve years ago in the same lakes indicate that the warming trend detected at Terra Nova Bay station during this period did not affect the biogeochemistry of water systems. Waters from a lake which recently experienced a lowering of the water level showed a remarkable increase in SO₄²⁻ concentrations. We hypothesized that the differential mobility of sulphate salts in the Antarctic soils, the biosynthesis of sulphur compounds in the lake, and the progressive decrease of the water volume are factors involved in the increase of SO₄²⁻ concentrations.