Soil Radionuclide Concentration and Radiological Assessment in selected Tourist Centres in Southwest Nigeria

Abstract

The natural radioactivity in the soils ofselected tourist centres in Southwest Nigeria was determined using gamma-ray spectrometer comprising a 3” x 3”Nal(TI) detector coupled to a Camberra series 10 MCA. Twenty(20) soil samples were collected from the five tourist centres. Four soil samples each were collected from Idanre hills (ID) in OndoState, Ikogosi warmspring (IKG) in EkitiState, Erin-Ijesha (EI) waterfall in OsunState, Olumo rock (OL) in OgunState,and Old Oyo National Park (OONP) in Oyo State. The Activity Concentrations (AC) were measured in Bqkg -1 . The AC at ID ranged from below detection limit (BDL) to 41.93±4.74 for 226 Ra, BDL to 49.37±2.90 for 232 Th, and 643.27±33.36 to 2040.16±104.33 for 40 K with respective mean values of 17.55±2.01, 23.61±1.86, and 1221.90±62.9. At IKG, AC ranged from BDL to 70.43±7.76 for 226 Ra and 75.25±3.94 to 550.16±28.69 for 40 K with mean values of44.51±4.94 and 255.14±13.38 respectively while 232 Th was BDL. At EI, AC ranged from BDL to 35.32±4.18 for 226 Ra, 139.60±7.37 to 452.71±23.60 for 40 K with mean values of 10.64±0.94 and 285.55±8.81 respectively while 232 Th was BDL. At OL, AC ranged fromBDL to 87.78±10.47 for 226 Ra, 3.95±0.23 to 84.08±4.99 for 232 Th, and 528.49±27.68 to 2159.01±112.85 for 40 K with mean values of 21.94±2.57, 52.66±10.34 and 1533.63±79.82respectively. For OONP, AC ranged from BDL to 72.66±7.72 for 226 Ra, and 247.04±13.12 to 611.10±32.05 for 40 K with mean values of 22.11±2.40 and 450.93±23.33 respectively while 232 Th was BDL.The maximum and minimum Absorbed dose rate meanvalues were foundto be 111.40±10.74 in OL and 16.82±1.19 nGyh -1 in EI respectively while that of the outdoor Annual Effective Dose and the Radium equivalent values for all the study centreswere also estimated and comapared to the world limits.