Evaluation of Natural Radoiactivity of Soil Samples in Some Selected Areas of Adamawa State, Nigeria

Evaluation of naturally, occurring radionuclides,²³⁸U,²³²Th and⁴⁰K. in the five locations of Adamawa state were carried out using gamma-ray spectrometry with well-type NaI detector to determine the natural radionuclides in the living environment and farmland soil samples to evaluate the hazards they might pose on the public. The calculated average activity concentrationsare 17.60 BqKg^-1, 5.16 BqKg^-1 and 847.24 BqKg^-1 respectively. The mean activity concentration of the radionuclides ²³⁸U, and ²³²Th in the present study are much lower than the worldwide average permissible values of 33 BqKg^-1 and 45 BqKg^-1 respectively. That of ⁴⁰K is higher than the world average value of 420 BqKg^-1. For those of the farmland soil samples, the average activity concentrations of the radionuclides: ²³⁸U, ²³²Th and ⁴⁰K were 17.95 BqKg^-1, 5.61BqKg^-1 and 891.34 BqKg^-1 respectively. It was also seenthat, the average activity concentration of ²³⁸U and ²³²Th are much lower, compared to the world allowed average of 33 BqKg^-1 and 45 BqKg^-1. In addition, that of ⁴⁰K is much higher than the world average of 420 BqKg-1. The study also revealed that the calculated of Ra_eq, absorbed dose rate and annual effective dose rate of the living environment, soil samples were found to be 90.20 BqKg^-1, 47.36 nGyh^-1 and 0.29mSvy^-1 respectively. Those of the farmland soil samples were also found to be 92.41 BqKg^-1, 49.69 nGyh^-1 and 0.3 mSvy^-1 respectively. The mean values of all the parameters are within the world average recommended safety limits. The internal commission on Radiological Protection (ICRP) has recommended the annual effective   dose equivalent limit of 1mSvy^-1 for the individual members of the public and 20mSvy-1 for the radiation workers.Therefore, it can be concluded that the present study areas are safe from radiation hazards with no harmful effects posed to the living population in the environments.