Application of radium and radon isotopes in studies of groundwater supply to rivers and to coastal regions

The objective of the present study is to serve as a guide to researchers who want to employ isotopes of radium (²²⁸Ra, ²²⁶Ra, ²²⁴Ra, ²²³Ra) and radon (²²²Rn) as natural tracers in studies involving groundwater discharge to coastal regions (Submarine Groundwater Discharge, SGD) and to rivers and water bodies. Hydrogeological studies using such tracers are lacking in Brazil. Potential reasons are the need of specific knowledge, expertise and equipment. The reader will find in this paper a brief description of the methods used to measure Ra and Rn isotopes and the basic foundations that guide these application. (author)