Affiliations: [a] Department of Environment Studies, Panjab University, Chandigarh, India | [b] Department of Environmental Sciences, Central University of Himachal Pradesh, Dharamshala, India
Abstract: Increased human influence has warmed the atmosphere, ocean and land thereby resulting in widespread and rapid changes in the atmosphere, ocean, cryosphere and biosphere (IPCC, 2021). High altitude lakes are generally small and quite sensitive to natural and anthropogenic perturbations. The present work is a preliminary work to investigate different hydro chemical processes and factors that controls the geochemistry of a high altitude lake, Lam Lake (dal) and its consecutive six lakes flowing through the Chamba district, Himachal Pradesh. Two hundred and eighty (n=280) water samples were collected in the year 2017 during the pre-monsoon and post-monsoon season. The anion concentration for all the seven lakes followed the trend HCO3- > NO3- > Cl- > SO42- > PO43- whereas the order of cation concentrations was Ca2+> Mg2+> Na+> K+ for both the seasons. Less EC of the water samples shows its serene nature. Components of bicarbonate (HCO3-) were found to be the major anion whereas calcium (Ca2+) was found to be the major cation present in the lakes. Piper Plot and Durov plot indicated Ca2+ – HCO3- as the major hydrogeochemical facies with comparatively less contribution from Mg2+–HCO3- type. The dominance of Ca2+ – HCO3- over Mg2+– HCO3- reflects the possibility of the natural order of dominance in the geology of the catchment area. The low Na+ + K+/TZ+ (total cations) ratios and the high Ca2+ + Mg2+/TZ+ (total cations) and (Ca2+ + Mg2+)/(Na+ + K+) ratios showed dominance of carbonate weathering. The average carbon ratios during pre-monsoon and post-monsoon were found to be 0.97 and 0.98, respectively, suggesting that proton is primarily derived from the oxidation of sulphide involving carbonate dissolution. The baseline data generated for a high-altitude lake shows that weathering and erosion during monsoonal precipitation and snow melt runoff during ablation season are the main sources of the chemical composition of lake water. Further to trace the imprints of climate change and seasonal variations in the high-altitude lakes, long term monitoring is recommended along with isotopic tracer techniques.
Keywords: High-altitude lake, Hydrochemistry, Geochemistry, Weathering, Major ions
