Water-Rock Interactions in the Bauru Aquifer System - São Paulo State, Brazil

The study focuses on the assessment of mineral saturation indexes using data of physicochemical analysis of groundwater samples from different units of the Bauru Aquifer System, in the State of São Paulo, Brazil. The analysis revealed that calcite (CaCO3) undersaturated waters dominate in the aquifer, but eventually groundwater reaches saturation with respect to this mineral. The majority of water samples are supersaturated with quartz, SiO2, and undersaturated with amorphous silica, SiO2(am). In the equilibrium diagrams, the samples are predominantly concentrated in the stability fields of the kaolinite and montmorillonite, which indicates that these mineral phases are the most probable sinks for Si and Al derived from weathered aluminosilicates.