Enhancement of uranium 234 in springwaters of Águas da Prata, São Paulo, Brazil

Springwater samples were collected at Águas da Prata, an important spa in Sāo Paulo State, Brazil. The 238 U and 234 U isotopes were evaluated for Platina, Paiol, Villela, Prata‐Radioativa, Prata‐Nova, Boi, Vitória, and Prata‐Antiga springs. An inverse logarithmic correlation was found between 234 U/ 238 U activity ratio and 222 Rn content of the studied waters, which was related to different solution mechanisms of 222 Rn and 234 U nuclides at the rock‐water interface. A linear correlation also exists between the 234 U/ 238 U activity ratios of the studied waters and total dissolved solids, ionic strength, CO 2 partial pressure, and index of base exchange, which indicates that the enhancement of 234 U in solution increases with the degree of weathering in the aquifers. A higher 234 U/ 238 U activity ratio was found to be directly related to a higher value of dissolution rate.