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

Abstract Groundwater in the Qinghai–Tibet Plateau (QTP) is mainly distributed active layer. Rising temperatures and human activities have influenced hydrogeochemical characteristics of QTP recent years. This study investigates hydrochemistry stable isotope (δ18O δD) variations groundwater Beiluhe Basin, which located China, during a freezing–thawing period Results show chemical types are HCO3 • Cl–Na Ca Mg, converted to Cl HCO3–Na Mg freezing At different stages layer, evaporation, concentration, rock weathering control composition this region. The main ion ratio coefficients saturation indices related minerals indicate that halite, dolomite, calcite relevant components water area. isotopic results δ18O δD fluctuations lake affected by runoff, temperature, evaporation. provides scientific basis for evolution utilization high-altitude areas.