Occurrence and remediation of naturally occurring radioactive materials in Nigeria: a review

Abstract

It is commonly believed that radioactive pollution originates mainly from anthropogenic activities, yet studies have revealed that naturally occurring radioactive materials account for over 80% of human exposure to ionizing radiation. In particular, reports suggest that severe health risks are associated with exposure to elevated concentrations of radioactive materials such as potassium 40K, uranium 238U and 235U, and thorium 232Th. Few reviews address the occurrence, risk assessment, and potential remediation strategies of radioactive pollution in Nigerian environments. In waters, concentration as high as 2.42 ± 0.28 Bq/L has been reported in rivers, which is much higher than the radionuclide permissible level of 1 Bq/L. In soils, activity concentrations of gamma-emitting radioactive materials are higher than the worldwide average crustal values. In air, the absorbed dose rates are also often higher, of 86.44 nGy hr−1, than acceptable limits of 60 nGy hr−1. The level of radionuclides is indicative of the type and mineral composition of the parent rocks. Advances in remediation technologies suggest that electroremediation, bioremediation, and adsorption are the most efficient approaches for decontamination.