AMMONIUM, ALKALINE AND ALKALINE-EARTH ELEMENT DETERMINATION IN ANTARCTIC LAKE WATERS, FLOWING MELT WATERS AND SNOW

Concentrations of lithium, sodium, potassium, magnesium and calcium were measured by ion-chromatography in samples collected in different sites during the 1989/90 Italian expedition in Antarctica. Sea waters, lake waters, flowing melt waters and snow were considered. In addition ammonium was determined in all the samples whenever the chromatographic separation of adjacent sodium and ammonium peaks was feasible. For each element the observed intervals of concentrations (shown in brackets) were: Snow (concentrations in muM units): Li(not detectable);Na(3-22);NH4(0.3-13); K(0.2-1); Mg(0.4-2); Ca(0.3-1). Lake and melt waters (in mM units): Li([0.4-4]X10(-3));Na(0.1-6);K(0.01-0.3);Mg(0.01-0.6);Ca(0.006-0.6). The lowest concentrations were found in melt waters. Sea waters (in mM units): Li([22-27]X10(-3)); Na(418-472); K(8.7-10); Mg(49-56); Ca(9.2-11). The above data represent the intervals of variability due to the non-homogeneity of composition among the sampling sites; for sea water, they include the water column depth effect. Correlations were searched for between relative concentrations of the analytes for the different natures of the samples in order to distinguish the origin of salt content both in snow and meltwater from marine aerosols and other environmental sources.