Phosphorus fertilizers as a source of uranium in Serbian soils

Abstract

Around 1500 t of mineral fertilizers based on phosphorus are applied per annum in Serbia. It is estimated that around 210 kg of uranium (30 g/ha) are in this way introduced into the environment. Due to this fact there is a risk of exposing local population to ionizing radiation. The purpose of this article was to determine whether long-term application of phosphorus fertilizers causes increase of uranium content in arable soils. These investigations were made using field experiments that were set up on three types of soil, chemozem, smonitza and pseudogley, more than 30 years ago. Same variants of mineral nutrition were used in these experiments and all fields had parcels without application of fertilizers (controls). Soil samples were taken from two soil layers (0-30 cm and 30-60 cm) continuously in a period of five years. Statistical analysis of the results obtained indicates that significant differences exist between the control and application of phosphorus fertilizers in the layer from 0-30 cm, while no such differences were found for the layer from 30-60 cm. Physicochemical soil properties change the process of uranium migration and mobilization. Indeed the fixation of uranium by investigated soil types decreases in the following order: chemozem>smonitza»pseudogley. Since the natural content of uranium in Serbian soils is in the interval from 0.08 to 5.9 ppm, it can be concluded that the results obtained in this investigation are within natural limits. Indeed, the values obtained for total uranium content in the investigated experimental variants were in the range from 0.65 to 1.94 ppm. This finding is of great value from the aspect of environmental protection and prevention of uranium of anthropogenic origin to be incorporated in food chain.