ASSESSMENT OF RADIOACTIVITY LEVELS AND TRANSFER FACTOR OF NATURAL RADIONUCLIDES AROUND IRON AND STEEL SMELTING COMPANY LOCATED IN FASHINA VILLAGE, ILE-IFE, OSUN STATE, NIGERIA

Abstract

This study assessed the radioactivity levels and transfer factor of natural radionuclides around iron and steel smelting company located in Fashina village, Ile-Ife, Osun State, Nigeria. This was with a view to evaluate the exposure rate of the study area, determine the radionuclides present and activity concentration (238U and 232Th and 40K) in the samples and evaluate the soil-to-food transfer ratio of the radionuclides. A portable survey meter with a Global Positioning System (GPS) were used for in-situ investigation and a well-calibrated NaI(Tl) detector system was used for the radioactivity measurement of the samples. A total of 38 samples comprising soil, food and water were collected at the study area (Fashina) and control area (Opa) in Osun state, Nigeria for spectrometry analysis. The soil and food samples were oven dried, pulverized and sieved while water samples were acidified with 10 mL of 11 M HCl per litre to prevent adsorption of radionuclides with the wall of the container. All the samples were then sealed and kept for at least 28 days in radon impermeable cylindrical container so as to reach secular equilibrium. The mean exposure rates in the study area were 0.14 µSv hr-1 and 0.12 µSv hr-1 for the control environment. The mean radioactivity content obtained for 238U, 232Th and 40K were 12.14 ± 4.17 Bq kg-1, 23.23 ± 7.67 Bq kg-1 and 270.14 ± 61.79 Bq kg-1 respectively in soil samples and 8.56 ± 2.80 Bq kg-1, 13.17 ± 4.48 Bq kg-1 and 89.41 ± 24.15 Bq kg-1 respectively in food samples. Similarly it was 7.64 ± 2.95 Bq L-1, 10.04 ± 3.43 Bq L-1 and 69.04 ± 15.49 Bq L-1 respectively for 238U, 232Th and 40K in water samples. The transfer factor from soil to food for 238U, 232Th and 40K were calculated from the activity concentrations of soil and food, while the means were 0.73, 0.61, and 0.39 respectively in the study area.