Variations of chemical features in a monsoon glacier watershed, southeastern Tibet Plateau

Abstract

The pH, EC (electric conductivity), d 18 O and major ions in melt water, precipitation, runoff and groundwater samples which were collected in Baishui basin were analyzed. Based on chemical analysis, the characteristic variations are analyzed in this paper. The melt water, precipitation, runoff and groundwater were Ca 2? /Mg 2? /HCO 3-type with similar ion compositions but showed different ion concentrations. Normally the content is high in groundwater and runoff water but low in melt water and precipitation. From the upper basin glacier downward, there was a general increasing trend for the total ion concentrations in basin. HCO 3 -and Ca 2? accounted for more than 80 % of total ions in samples, indicating that ions mainly came from limestone and water typical of carbonate solution water. Water-rock interaction is the significant contributor to water geochemistry. The concentration of inorganic ion in melt water had an obvious diurnal variation with temperature change. The d 18 O values increases with the altitude decrease; the similarity of d 18 O in runoff and groundwater samples was due to their frequent transformation in karst regions.