New research on the Rulung Glacier in Ladakh shows that Himalayan glaciers are not only frozen reserves of freshwater but also active chemical systems. The study examined meltwater from four sites during the ablation period in 2023 and 2024 and found that rising temperatures and faster glacier melt are intensifying interaction between meltwater and rocks below and around the ice. This can alter water chemistry in streams that feed the Indus river basin.
The meltwater was dominated by alkaline freshwater conditions. Its pH values ranged from 7.75 to 8.16, while Total Dissolved Solids stayed below 500 mg/L at all sampled locations, placing it within the desirable drinking water category. The water initially acquired ions from carbonate-rich metamorphic rocks near the glacier snout, including gneiss, schist and calcite-bearing formations. As it moved through subglacial paths, streams and lakes, longer water-rock interaction, mineral oxidation, carbonate and silicate dissolution, sediment transport and changing discharge further modified its chemistry.
Scientists warned that prolonged warming and glacier retreat may expose fresh rock surfaces, enhance oxidation reactions and potentially increase trace metals downstream. Moderate minerals such as calcium and bicarbonate can support buffering and nutrients, but higher sediment, salts or trace elements may affect aquatic habitats, irrigation suitability, soil quality and drinking-water treatment needs. The case highlights why glacier monitoring must include water quality, not only ice loss and river discharge.