Study of activity concentrations of 40 K, 238 U and 232 Th for assessment of radiation dose in agricultural soils of southwestern Nigeria

Abstract

Gamma spectrometric measurement of natural radionuclides activity concentrations by HPGe detectors was conducted in 150 agricultural soil samples collected from six states of southwestern Nigeria. The overall activity concentrations of radionuclides ranged from 15.27 to 972.00 Bqkg⁻¹ for ⁴⁰K, 0.66 to 336.19 Bqkg⁻¹ for ²³²Th and 1.32 to 123.01 Bqkg⁻¹ for ²³⁸U, with mean values of 143.95, 17.02 and 22.92 Bqkg⁻¹, respectively. The overall averages results from this study were generally lower than worldwide average value of 420, 33 and 45 Bqkg⁻¹ for ⁴⁰K, ²³⁸U and ²³²Th, respectively, thus minimal transfer to plant may be expected. The estimated radiation dose levels of the soil indicated acceptable limits for general public exposure. The radioactivity levels of ⁴⁰K, ²³²Th and ²³⁸U in the investigated agricultural soil of southwestern Nigeria are within acceptable limits. Therefore, stochastic radiological health effects of radiation exposure by farmers may not be feasible at the current moment.