Assessment of groundwater hydrogeological processes, isotopic composition, and associated health risks of the Banaz (Usak) Basin, Turkey.

The study area covers the Banaz (Usak) basin located in the Aegean Region in the western part of Turkey. Metamorphic, sedimentary, ultramafic, and volcanic rocks are dominant in the basin. The groundwaters in the study area are used for domestic, irrigational, and industrial purposes. Hence, the groundwater chemistry and major geochemical processes in the region were determined. The dominance of major elements was of the order of Ca²⁺ > Mg²⁺ > Na⁺ > K⁺ and HCO₃^- > CO₃^- > Cl^- > SO₄^2-. Piper, Durov, Chadha, and Radial plots identified generally Ca²⁺-Mg²⁺-HCO₃^- type waters as the dominant types of water in this area. In terms of physical parameters in the basin, the waters are suitable for drinking. However, arsenic content in Yesilyurt and Corum settlements exceeds the limit values of drinking water standards. In addition, the ammonium value is high in the water sample in the Corum region. Isotope contents in water samples from 2008 to 2023 were evaluated in the study area. The waters in the basin are of meteoric origin according to their stable isotope content. Tritium content in the plain waters indicates recent recharge. Additionally, for children, As and U elements were identified as risky with oral intake and As with dermal contact.