Hydrochemical characteristics of meltwater draining from Pindari glacier, Kumaon Himalaya

A detailed geochemical study of the Pindari glacier meltwaters has been car ried out to assess the major ion chemistry and solute acquisition processes at high altitude. Electrical conductivity of the meltwater ranges from 69 to 207 muS cm(-1). Analytical result shows that bicarbonate and sulphate ar e sub-equally dominant anions, accounting for 49% and 50% of the total anio ns respectively in equivalent unit. In equivalent unit, calcium is found to be the most dominating cation (74%) followed by magnesium (20%) potassium (3.5%) and sodium (2.5%). Ca-SO4-HCO3 is the dominating hydrochemical facie s in Pindari glacier meltwater. High contribution of calcium and magnesium to the total cations (90-95%), high (Ca+Mg)/HCO3 and (Ca+Mg)/(Na+K) ratio i ndicate that the composition of meltwater draining from Pindari glacier is largely controlled by carbonate weathering and partly by silicate weatherin g. High concentration of sulphate and average C-ratio (HCO3/HCO3+SO4) value of 0.49 suggests that coupled reactions, involving carbonate dissolution a nd protons derived primarily though not exclusively from the oxidation of s ulphide minerals, largely control bulk meltwater composition. Low concentra tions of dissolved ions were observed in the early ablation (May and July) seasons, while the late ablation seasons (September and October) are marked by increased concentrations of observed species.