Hydrochemistry and dissolved solute load of meltwater in a catchment of a cold-arid trans-Himalayan region of Ladakh over an entire melting period

The hydrochemical study of meltwater draining from a catchment dominated by snowmelt in a cold-arid trans-Himalayan region of Ladakh, India, was carried out for an entire melting season (May-September) during the year of 2010. Cation concentration in the meltwater shows a consistent trend of Ca >> Mg > Na > K for this period. Carbonate weathering has been identified as the dominant process controlling the dissolved ion chemistry of meltwater in the study area. There are indications that atmospheric aerosols contain alkaline dust, sea salt and anthropogenic aerosols like NO3 and SO4 that might have also added some solute to the system. Meltwater chemistry has been showing an intra-annual variation with highest concentration for most of the dissolved solutes during the late melt period, pointing towards the contribution of ground ice melt to the catchment runoff. The lowest concentration during the peak melt period is due to higher contribution from snow melt which has less residence time to interact with rock. Cationic denudation rate for this catchment has been estimated as 778 meq m(-2) a(-1), while the average total dissolved solids flux for early, peak and late melt period is 0.64 t day(-1), 3.02 t day(-1), 1.31 t day(-1), respectively.