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

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 for K, 0.66 to 336.19 Bqkg for Th and 1.32 to 123.01 Bqkg for U, with mean values of 143.95, 17.02 and 22.92 Bqkg, respectively. The overall averages results from this study were generally lower than worldwide average value of 420, 33 and 45 Bqkg for K, U and Th, 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 K, Th and U 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.