Speaker
Description
The fertilizer industry employs raw materials that naturally contain radionuclides. The processing of these materials during fertilizers production leads to the generation of by-products in which the initial radionuclide content is enhanced. One of the management practices implemented over the years has been the storage of this phosphate waste in open-air piles and ponds. Among the radionuclides present, radium-226 and uranium-238 are typically observed, together with their respective decay products including radon gas. The exposure to radon through inhalation constitutes the second leading reason for lung cancer deaths worldwide. When radon comes into contact with water bodies, it can dissolve and be transported, potentially becoming a source of exposure. Radon in waste ponds exposed to rainfall or water intrusion can be mobilized and dissolved in the water. This study focuses on radon leaching and, if applicable, the potential leaching of radium, its parent radionuclide, under irrigation conditions representative of these scenarios. The configuration of phosphate ponds is reproduced at laboratory scale using leachate columns containing phosphate waste overlying non-contaminated soil. The leachates are extracted by percolation and using soil moisture samplers at different points along the column, while the conductivity, temperature and moisture of the non-contaminated soil are continuously monitored. After sampling, the radon concentration of the leachates is determined by Liquid Scintillation Counting using a Hidex 600SL detector. The aim of this work is to examine how radon may be mobilized from phosphate residues. Its transport is studied considering both direct contact with the residues and as water moves through the underlying soil. Characterizing radon transport by leaching will enable assessment of its potential as a source of exposure and support further prediction and mitigation actions.