Aspects of weathering and solute acquisition processes controlling chemistry of sub‐Alpine proglacial streams of Garhwal Himalaya, India

摘要

An analytical study of major cations and anions of the proglacial streams of Garhwal Himalaya has been carried out to assess the weathering and geochemical processes in high altitude river basins. Calcium and magnesium are the major cations, and bicarbonate and sulphate are the most dominant anions in these waters. A high correlation among HCO, Ca and Mg, a relatively high contribution of (Ca+Mg) to the total cations (TZ) and high (Ca+Mg&;Na+K) ratio indicate carbonate weathering could be the primary source of the dissolved ions. Carbonic acid weathering is the major proton-producing reaction in the Alaknanda River, while in the Bhagirathi River it is the coupled reaction which controls the solute acquisition processes. To know the geochemical factors controlling the chemical nature of water, R-mode factor analysis on major ion data from Ganga headwater streams has been performed. Factor 1 in the Alaknanda River is explicitly a bicarbonate factor showing strong loading of EC, Ca, Mg, HCO and TDS. In the Bhagirathi River Factor 1 explains the sulphide dissolution and silicate weathering and Factor 2 explains carbonate weathering. Wide downstream variations are observed in the total dissolved solids (TDS) and total suspended matter (TSM) in the headwater streams of the Ganga. Quartz and feldspar are the common detrital minerals, and kaolinite and illite the common clay minerals in the suspended sediment. Copyright © 2002 John Wiley & Sons, Ltd.