FIRN-CORE STUDY FROM THE SOUTHERN PATAGONIA ICE CAP, SOUTH-AMERICA

A shallow firn core, recovered from the southern Patagonia ice cap (elevation 2680 m a.s.l.), has been analyzed for H stable isotope composition and for major soluble chemical compounds. The temperature measurement at 13.17 m depth (bottom of the core) shows that the ice cap is temperate. The chemical profiles indicate that some soluble impurities have been partly washed out by percolation, but seasonal deuterium content variations are relatively well preserved down to the bottom of the core, which allows the net accumulation rate of the site to be calculated (1.2 m water equivalent). The mean concentrations measured in the most recent year recorded (Cl-:4.85, nssSO42-:0.65, NO3-:0.32, Na+:4.30, K+:0.64 and NH4+:0.77, in mueq.l-1) serve as a reference for the background chemical composition of precipitation at mid-southern latitudes under South Pacific meteorological conditions.