An alternative approach to efficiency tracking in thorium determination in fertilizers by alpha spectrometry

Fertilizers play a key role in increasing crop yield per unit land answering the growing demand for food production. However, excessive or improper use of fertilizers can lead to several environmental issues including soil contamination. One of the known contaminants attributed to fertilizers are radionuclides. The goal of this study was to determine the concentration of thorium isotopes in several types of commonly used fertilizers produced in Poland. The methodology included the use of an alternative tracer (namely ²²⁸Th) to evaluate chemical recovery. The correctness of the proposed method was confirmed by analyzing certified reference materials. The obtained results showed that the activity concentration of ²³²Th was ranged from <0.34 Bq kg^-1 for nitrogenous fertilizer up to 97 ± 22 Bq kg^-1 for pure phosphate fertilizer.