Chemical characterisation of meltwater draining from Gangotri Glacier, Garhwal Himalaya, India

Abstract

A detailed analytical study of major cations (Ca2+, Mg2+, Na+, K+) and anions (SO2-4, HCO-3, Cl-, NO-3) of meltwater draining from Gangotri Glacier was carried out to understand major ion chemistry and to get an insight into geochemical weathering processes controlling hydrochemistry of the glacier. In the meltwater, the abundance order of cations and anions varied as follows: Ca2+ > Mg2+ > K+ > Na+ and SO2-4 > HCO-3 > Cl- > NO-3, respectively. Calcium and magnesium are dominant cations while sulphate and bicarbonate are dominant anions. Weathering of rocks is the dominant mechanism controlling the hydrochemistry of drainage basin. The relative high contribution of (Ca+Mg) to the total cations (TZ+), high (Ca+Mg)/(Na+K) ratio (2.63) and low (Na+K)/TZ+ ratio (0.29) indicate the dominance of carbonate weathering as a major source for dissolved ions in the glacier meltwater. Sulphide oxidation and carbonation are the main proton supplying geochemical reactions controlling the rock weathering in the study area. Statistical analysis was done to identify various factors controlling the dissolved ionic strength of Gangotri Glacier meltwater. © Indian Academy of Sciences.