Evaluation of natural radioactivity and assessment of dose increase due to the use of fertilizers produced in Poland

Some types of fertilizers may contain various amounts of natural radionuclides like ²³⁸U, ²³²Th, ²²⁶Ra, ⁴⁰K (Kuzmanoviae et al. in J Radioanal Nucl Chem 331(12):5825-5834, 2022. 10.1007/s10967-022-08646-x; H Hamamo et al. in J Radioanal Nucl Chem 194(2): 331-336, 1995. 10.1007/BF02038431; M Garcia-Leon et al. in J Radioanal Nucl Chem 197(1): 173-184, 1995. 10.1007/BF02040229). In this study 16 samples of commercially available fertilizers produced in Poland were selected for preliminary radiological evaluation. The samples were measured by means of low background gamma spectrometry. The results showed high concentrations of ⁴⁰K in potassium and multinutrient fertilizers (2.3-13.8 kBq kg^-1), and relatively high concentrations of uranium and radium isotopes in phosphate fertilizers. The obtained results allowed to calculate radium equivalent activity, absorbed dose rate increase and increase in annual effective dose equivalent. (author)