Determination of the Distribution of Gamma Emitting Radionuclides in Abeokuta using an In-Situ Gamma Spectrometric System

Abstract

In all ground formations, naturally occurring radionuclides, such as 40K, 226Ra and 232Th and their decay products exist as trace levels. In this study, in-situ gamma spectrometry, which consists of a NaI(Tl) detector, a portable shield 4 cm thick and 17.5 cm deep which was filled with lead shots and a mobile stand has been used to measure different components of environmental radioactivity around Abeokuta, capital of Ogun State, Southwestern Nigeria. Results from the study shows that 40K, 226Ra and 232Th has a mean of 469.28 ± 4.09, 65.11± 0.27 and 558.93 ± 6.61 Bq/kg correspondingly. Calculated values for absorbed dose rate are as follows: 451.27 nGy/h for the mean, 86.76 nGy/h for the lowest, and 1635.92 nGy/h for the highest. The mean value of the yearly effective dosage is 0.99 mSv/y, with low value of 0.22 mSv/y and high value of 4.22 mSv/y. The minimum value exceeds the maximum value. Based on the findings of this investigation, one may draw the conclusion that the comparatively high activity concentration level of the city can be attributed to the unexpectedly high concentrations that were found at some sites.