Strontium Isotopic Signature of Groundwater from Adamantina Aquifer, Bauru Basin, Brazil

Using 87Sr/86Sr ratios and the geochemistry of groundwater we were able to identify different hydrochemical facies in the Adamantina aquifer, Bauru Basin (Brazil). Samples from shallow wells show Cl-NO3-Ca-Mg water with low pH due to natural and anthropogenic recharge. The 87Sr/86Sr ratios are greatest in the shallower parts of the aquifer (0.7134) and decrease with increasing well screen interval depth. The nitrate concentration gradually decreases with depth and aquifer pH increases, HCO3 predominates as the main anion, and the groundwater becomes saturated with respect to calcite, with average 87Sr/86Sr ratios of 0.708694 at depth.