Radiological and chemical assessment of Uro and Kurun rock phosphates

This study investigates the natural radionuclide content of Uro and Kurun rock phosphates in western Sudan, aiming to assess their radiological and chemical safety for agricultural use. Through the application of gamma spectrometry techniques, including high-resolution gamma spectrometry, we determined the activity concentrations of uranium-238 and its decay products, which emerged as the main contributors to radioactivity in the phosphate deposits. Our findings revealed that the highest activity concentrations were present in grey-coloured rock phosphate samples. We calculated the mean activity concentrations impacted by an average agricultural application of 300 kg per hectare of untreated ground rock phosphate fertilizer, resulting in significant annual distributions of radium-226, thorium-232, and potassium-40 for both Uro and Kurun fertilizers. Moreover, external radiation exposure estimates were derived for areas where these fertilizers are applied, indicating negligible contributions to the population's terrestrial radiation exposure. However, the air exposure rates above the phosphate deposit areas exhibited a potential concern, highlighting their classification amongst high background radiation regions. Additionally, evaluations of the maximum emanation power suggested minimal contamination risk for agricultural soil due to Kurun rock fertilizer compared to unfertilized soils in Sudan.