Concentration de l’uranium -application aux fertilisants agricoles

Abstract

This study focuses on measuring the activity concentration of natural radionuclides in two types of agricultural soil from the Sétif region—both before and after fertilization—as well as in samples of NPK and NPKs fertilizers, using gamma spectrometry. The results show no significant variation in soil radioactivity levels following fertilization, with values ​​generally comparable to global averages for ²²⁶Ra, ²³²Th, and ⁴⁰K. In contrast, the fertilizers exhibit higher radionuclide concentrations than the soils. The study highlights a specific radioactive disequilibrium within the uranium-238 decay series—observed between ²³⁸U and ²²⁶Ra—in both the soils and the fertilizers. This disequilibrium is attributed to the processing of raw materials used in fertilizer production and, in the case of soils, to uranium input associated with the use of phosphate fertilizers. The increasing use of phosphate fertilizers and the production of phosphoric acid from phosphate rock can thus contribute to the redistribution of natural radioactivity in the environment. Regarding thorium, no significant excess was observed in the soils, whereas higher values ​​were recorded in the fertilizers.