RESUMEN
Assessment of activity levels of radionuclides that exist in soil, granite, and charnockite rock samples is very crucial because it exhibits an enhanced elemental concentration of uranium (U) and thorium (Th) contributing higher natural background activity than usual in the environment and it may cause health risk to human health through the external and internal exposure. This study determined the radioactivity levels of 238U, 232Th, and 40K radionuclides in soil, granite, and charnockite rock samples collected from selected fields in Ekiti State, Nigeria using Caesium iodide CsI(Tl) scintillation gamma spectrometer. It also evaluated indices of the radiological parameters consisting of radium equivalent activity (Raeq), absorbed dose rate (DR), annual effective dose equivalent (AEDE), internal hazard index (Hin), and excess lifetime cancer risk (ELCR). The calculated average activity concentrations of 238U, 232Th, and 40K are 30.40 ± 0.71 Bq kg-1, 3.31 ± 0.05 Bq kg-1, and 222.25 ± 14.72 Bq kg-1, respectively, which were lower than their respective world average values. Comparatively, potassium concentrations in these collected samples have a higher value than concentrations of uranium and thorium (40K > 238U > 232Th). All the evaluated values of the radiological parameters (except DR) of the appraised radionuclides were below the global permissible limits. The granite rocks, charnockite rocks, and soils from Ekiti State in Nigeria do not pose any hazardous risk to humans, but continued monitoring is necessary when these materials are used as building materials, which cause long-term radiation exposure.
RESUMEN
In this present study, the activity concentration of the naturally occurring radionuclides 238U, 232Th and 40K have been measured in commonly used chemical fertilizers for agriculture by using gamma-ray spectrometry with NaI (TI) detector. Radiological hazard parameters have been calculated for samples. The mean specific activity concentration of the 238U, 232Th and 40K is 176, 5.75 and 4136 Bq kg-1, respectively. Particularly, the mean value of 238U, as well as 40K, is higher than the world recommended value. Also, the average value of radium equivalent activity is 503 Bq kg-1 and the absorbed dose rate (DR) is 282.93 nGyh-1, which is greater than the permissible limit, whereas the annual effective dose rate (AEDR) is 0.316 mSvy-1, which is lower than the world recommended value. Therefore, collected fertilizer samples significantly increase the activity concentration of natural radionuclides in the agricultural soils. Multivariate statistical techniques such as Pearson correlation and factor analysis are carried out for radioactive variables to understand the existing relationship between them. From obtained results reveals that these fertilizer samples increases the probability of adverse health effects due to natural radioactivity.
