Thermodynamic control on chemical weathering of river bedrock at the Aba and Qamdo in Kaschin-beck disease region, eastern Tibet Plateau

Groundwater is the main source of water for living and agriculture in an area. To investigate the relationship between water environment and Kaschin-beck disease (KBD), we collected published data on water samples (data from the KBD areas of Aba Prefecture, Qamdo area, the Yellow River Basin region and the non-KBD area of the Yangtze River Basin region) for thermodynamic simulations to further analyze the hydrogeochemical properties. The analysis results show that: (1) The groundwater in Aba Prefecture and Qamdo area is weakly alkaline. (2) The groundwater type in Aba Prefecture and Qamdo area is Ca-HCO3− type. (3) The average concentration of cations Mg2+and Ca2+ can be expressed as Yellow River Basin > Yangtze River Basin > Aba Prefecture > Qamdo area. The average concentration of cation Na+and anion Cl− can be expressed as Yellow River Basin > Qamdo area > Yangtze River Basin>Aba Prefecture. The value of TDS can be expressed as Yellow River Basin > Qamdo area > Yangtze River Basin > Aba Prefecture. This may indicate that there is no direct relationship between KBD and water environment. (4) The dissolution of calcite and dolomite in quartzite controls the change of element content of water. (5) Analysis of the Gibbs distribution shows that most of the elements in the groundwater of the KBD areas (Aba Prefecture, Qamdo area and the Yelllow River Basin region) and non-KBD area (the Yangtze River Basin region) majorly come from rock weathering. (6) The overall quality of groundwater is good, the salinity is low, and it is suitable for agricultural irrigation.