Effect of mineral fertilisers application on the transfer of natural radionuclides from soil to radish (Raphanus sativus L.)

Non-controlled usage of mineral fertilisers in agriculture land of Kazakhstan is a concerning issue, due to possible contamination of the soil by radionuclides. Pot experiment of growing of R. sativus with application of mineral fertilisers was carried out under natural conditions. Two commonly used mineral fertilisers, mono-potassium phosphate and ammonium nitrate, were chosen in the frame of current research to determine the impact of mineral fertiliser on transfer of natural radionuclides from soil to R. sativus edible part. For this goal, the activity concentrations of natural radionuclides U-234, U-238, Th-230, Th-232 and Ra-226, were determined in both R. sativus edible part and the investigated soil by using alpha-particle spectrometry. The highest activity concentrations were found for R. sativus edible part growing on soil that was fertilised by mono-potassium phosphate and were equal to 174 ± 17, 134 ± 15, 62 ± 4, 15 ± 2 and 2.8 ± 0.6 Bq/kg for U-234, U-238, Th-230, Th-232 and Ra-226, respectively. The results of soil-to- R. sativus edible part transfer factor for different radionuclides varied depending on the mineral fertiliser used. For evaluation of impact during consumption of R. sativus edible part by a population of Kazakhstan, annual effective ingestion dose and excess lifetime cancer risk were determined. The highest annual effective ingestion dose was found for R. sativus edible part cultivated in mono-potassium phosphate-fertilised soil and was equal to 4.4 μSv year−1. •Addition of mono-potassium phosphate increase bioavailability of radionuclides.•Mobility of uranium isotopes is enhanced by mono-potassium phosphate.•Application of mono-potassium phosphate contributes to changes in uranium speciation.