Measurements of Seasonal Variations of Radioactivity Distributions in Riverine Soil Sediment of Ado-Odo Ota, South-West Nigeria: Probabilistic Approach Using Monte Carlo

Abstract

The radioactivity levels were measured using a hand-held gamma-ray survey meter and NaI (Tl) based gamma spectroscopy to evaluate the seasonal variation of radioactivity levels in the riverine area of Ado-Odo Ota. The measured iso-dose map reported higher gamma dose rate of 79 nGy/h, approximately 34% higher than the world average of 59 nGy/h. The values for U-238, Th-232 and K-40 activity levels ranged between 29.9 and 21.6; 103.2 and 31.2; 802.2 and 233.5 with mean values of 26.1, 55.6 and 499.3 Bq/kg, respectively. According to the mean, 5th and 95th percentiles of the probabilities using the Monte Carlo simulation, the Radium equivalent activities and the absorbed dose rates are within their respective recommended limits of 370 Bq/kg and 84 nGy/h. This study could be used to monitor dose rates and radiological risks for the areas covering the small area (Ado-Odo Ota) to the larger area (West African Region) as baseline data.

Spatial Distribution of Gamma Dose Rates and Radioactivity Levels in Some Parts of Iju Community in Ado-Odo Ota, Ogun State

“…The implication here is that the zone is a spot where the majority of the community gather for different purposes daily. The values of the gamma dose rate for these hot spots are comparable with the values obtained by [7] and [9], respectively. The values are slightly above the recommended values according to [4], [10]- [11].…”

“…Thirteen (13) stations were calculated across the inquiry territory. As advised by the manufacturer, the instrument is given a 15-minute to stabilize and balance out before starting the estimating portion of the research to ensure accurate results [7], [9]. Every station's GPS ranges, or coordinates, were noted.…”

“…The converted field data acquired are presented in Tables 2 and also presented in Table2are the activity concentrations of naturally occurring radionuclides, dose rates, longitudes, latitudes and elevation acquired from Iju community. The results of 238 U, 232-Th and 40-K activity levels are discussed in different Figures below and compared with the International standard levels[1],[9]. Conversion Factor…”

Assessment of Radiation Levels and Potential Radiological Hazards in the Soils of Riruwai Mining Area, North-Western Nigeria

“…The amount of radioactivity in the soil is affected not only by soil type and usage but also by seasonal variations [16]. It has been reported that radionuclide concentrations are found to be higher in the dry season compared to the wet season [17]. Mining has been identified as a possible source of naturally occurring radionuclide exposure.…”