Major ion chemistry and assessment of weathering processes of the Patsio glacier meltwater, Western Himalaya, India

Major ion chemistry of meltwater draining from Patsio glacier was carried out between 2010 and 2012 to understand the meltwater chemistry and geochemical processes controlling hydrogeochemistry of the study area. Among the anions, bicarbonate is the major anion on average accounting for 52.5 % in 2010, 58.5 % in 2011 and 58.9 % in 2012 of the total anions (TZ⁻). Sulphate is the next dominant anion after bicarbonate on average accounting for 45.9 % in 2010, 36.3 % in 2011 and 39.8 % in 2012 of the total anions (TZ⁻). On the other hand, calcium is the major cation on average accounting for 71.9 % in 2010, 70.3 % in 2011 and 72.5 % in 2012 of the total cations (TZ⁺). The comparatively higher contribution of (Ca + Mg) to the total cations (TZ⁺), high value of (Ca + Mg)/((Na + K), good positive correlation between Ca-HCO₃ and low value of (Na + K)/TZ⁺ for all 3 years indicate that carbonate weathering is a dominant geochemical process controlling meltwater chemistry of the study area. The average Na/Cl and K/Cl ratios in the meltwater draining from Patsio glacier are much higher than marine aerosols indicating comparatively minor contribution from atmospheric precipitation to the chemical composition of meltwater of the study area. The average pCO₂ (effective CO₂ pressure) values of the meltwater of study area are higher than the atmospheric pCO₂ showing disequilibrium with respect to atmosphere and open system weathering. Statistical analysis (correlation matrix and factor analysis) was applied for identification of different factors controlling hydrochemistry of the Patsio glacier meltwater.