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

Concentrations of major ions (Cl-, NO3-, SO42-, Na+, K+,Mg2+, Ca2+) where measure in melting snow and water samples from stream and lakes in ice-free areas throughout northern Victoria Land. Most ions in snow and terrestrial water are derived from the marine environment and their concentrations are extremely variable in species 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 catchment, nesting seabirds and aquatic microbiota are among factors which most influence ion composition variability. Comparison with data from twelve years ago in the same lakes indicates that the warming trend detected in Terra Nova Bay station during this period did not affect the biogeochemistry of water systems. Water 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.