Factors controlling uranium and radium isotopic distributions in groundwaters of the West-Central Florida phosphate district

The processes involved in mining of uranium-rich phosphate ore are suspect in the liberation of uranium and its decay products to groundwater. Carbonate fluorapatite, the principal-phosphate bearing mineral in phosphorites of the study area, commonly contains 50 to 200 ppm of uranium. Present along with this uranium are decay products of the uranium-238 series including long-lived daughters uranium-234 and radium-226. Of concern in this investigation were the concentrations and relative distributions of uranium and radium-226 in groundwaters and sediments of the land-pebble phosphate district of west-central Florida. Concentrations and activity ratios of uranium-238, uranium-234 and radium-226 in soils and natural waters of mined and unmined terrains were compared within the phosphate area. In addition, groundwaters and sediments from an adjacent unmineralized area, in which radium-226 concentrations in groundwater were know to be elevated, were also studied in an attempt to better understand the hydrogeologic and geochemical factors affecting the distribution of these radionuclides