Hydrochemical and isotopic characteristics of surface water in the Lhasa River basin

In this study, 36 surface water samples were collected to investigate the hydrochemical and isotopic characteristics of the surface water in the Lhasa River basin using mathematical statistics, a Piper diagram, Gibbs plots, ratio graphs of ions and factor analysis. The dominance of the cations and anions in the surface water was Ca2+ > Mg2+ > Na+ > K+ and HCO3- > SO42- > Cl-. The mean concentrations of the cations and anions of the surface water were low in the study area. Human activities have a certain influence on the hydrochemical components of surface water in the study area. HCO3 center dot SO4 (SO4 center dot HCO3)-Ca center dot Mg (Mg center dot Ca) types of surface water were dominant in the study area. Water-rock interactions play a dominant role in controlling the surface water chemistry in the Lhasa River basin, mainly the weathering of silicate and carbonate, as well as the dissolution of sulfate minerals and cation exchange. Isotopic analysis indicated that the surface water was of meteoric and glacial/snow meltwater origin.