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Source of Gross-Alpha Radioactivity Anomalies in Recharge Wells, Central Florida Phosphate District


The central Florida phosphate industry utilizes recharge wells to mitigate withdrawals of water from the Floridan aquifer and to dewater the surficial aquifer prior to mining. From a water management point of view, these wells are efficient and serve a vital function. Recent monitoring of the radiation environment in these wells, however, casts doubts on the safety of the wells. While most of the wells conform to state and federal standards for radium, gross-alpha radiation frequently exceeds standards.

The purpose of this study was to determine the radionuclide(s) responsible for the high gross-alpha radiation and to identify a method for sampling of the recharge wells that would standardize data across the phosphate district. We found that there is, indeed, a radionuclide that causes the gross-alpha radiation to exceed standards and that sampling techniques, sample-preparation methods, and laboratory procedures grossly affect the results. This report constitutes our findings.