Paper Title
Analysis of U-Isotopes in Groundwaters from Aquifer Systems at São Paulo State, Brazil

Abstract
This paper describes the characterization of the natural radioactivity due to dissolved U-isotopes 238U and 234U ingroundwaters occurring in sedimentary (Bauru, Guarani, and Tubarão) and fractured rock (Serra Geral) aquifer systems in the Paraná sedimentary basin (PSB), Brazil.Based on the isotope dilution analysis, U concentration and 234U/238U activity ratio (AR) data have been utilized to deduce the proportions of groundwater masses in a mixture. Thus, this study reported a novel dataset focusing the presence of these radionuclides in selected different aquifer systems that will be used in further investigations aiming to perform approaches evaluating how mixing processes are taking place in such very important Brazilian hydrological resources. Keywords - dissolved U-238 and U-234, groundwaters, Paraná sedimentary basin, Brazilian state of São Paulo