ABSTRACT
The phosphate mining process appears to slightly disrupt natural radioisotopic patterns in groundwaters of all three aquifers. Radium concentrations in groundwaters from all three aquifers of the study area increase to the southwest, downgradient of the phosphate district. However, the oxidation-reduction potential and the ionic strength of the groundwater, directly related to its residence time within the aquifer, were identified as the major factors controlling uranium and radium-226 concentrations and activity ratios in groundwaters of the study area. In addition, groundwaters and sediments from an adjacent unmineralized area, in which radium-226 concentrations in groundwater were known to be elevated, were also studied in an attempt to better understand the hydrogeologic and geochemical factors affecting the distribution of these radionuclides. The average Ra concentration in groundwaters of all aquifers in the southern part of the study area exceeded the state and federal drinking water standard of 5pCi/l for combined activities of radium isotopes.
