Variation and reason analysis of groundwater hydrochemical characteristics in Beiluhe Basin, Qinghai-Tibet Plateau during a freezing-thawing period

Groundwater in the Qinghai-Tibet Plateau (QTP) is mainly distributed in the active layer. Rising temperatures and human activities have influenced the hydrogeochemical characteristics of the QTP in recent years. This study investigates the hydrochemistry and stable isotope (delta O-18 and delta D) variations of the groundwater in the Beiluhe Basin which is located in the QTP of China during a freezing-thawing period of the active layer. Results show the chemical types of the groundwater are mainly HCO3 center dot Cl-Na center dot Ca center dot Mg, which are converted to Cl center dot HCO3-Na center dot Ca center dot Mg during the freezing period of the active layer. At different stages of the freezing-thawing period of the active layer, evaporation, concentration, and rock weathering control the chemical composition of the groundwater in this region. The main ion ratio coefficients of groundwater and the saturation indices of related minerals in groundwater indicate that halite, dolomite, and calcite control the relevant chemical components of water in the study area. The stable isotopic results show that delta O-18 and delta D fluctuations in the lake water and the groundwater are mainly affected by groundwater runoff, temperature, and evaporation. This study provides the scientific basis for groundwater evolution and utilization in high-altitude areas.

Automated summary

This study investigates the hydrochemistry and stable isotope variations of groundwater in the Beiluhe Basin in the Qinghai-Tibet Plateau during a freezing-thawing period. The results show that the chemical composition of groundwater is influenced by evaporation, concentration, and rock weathering. The stable isotopic results indicate that groundwater runoff, temperature, and evaporation affect the fluctuations of isotopic composition in the groundwater.