Estimation of Natural Radionuclide Concentrations and Heavy Metal Contents due to Bitumen Exploitation at Gbeleju-Loda, Ode-Irele, Ondo State, Southwestern Nigeria

Abstract

Bitumen exploitation has resulted in the destruction of organisms over a large expanse of land and water bodies. Thus, the aim of this present study is to collect soil and plant samples at bitumen exploitation affected areas of Gbeleju-Loda Ode-Irele, Ondo State, Southwestern Nigeria in order to estimate the natural radionuclide concentrations (40K, 238U and 232Th) using a well calibrated NaI(TI) Scintillation Radiation Detector and heavy metal contents using an Atomic Absorption Spectroscopy (AAS) machine. The results obtained for natural radionuclide contents showed that 40K were present in the range 320.46 ± 45.16 to 543.23 ± 14.08 Bqkg-1; 238U were present in the range 24.33 ± 11.41 to 32.10 ± 16.25 Bqkg-1 while 232Th were present in the range 12.36 ± 8.12 to 20.41 ± 3.50 Bqkg-1 respectively in the soil samples. The results also showed that radionuclides were present in the concentrations of 145.16 ± 12.40 to 280.35 ± 27.32 Bqkg-1 for 40K, 10.62 ± 4.91 to 22.24 ± 3.51 Bqkg-1 for 238U and 6.34 ± 5.28 to 9.58 ± 3.07 Bqkg-1 for 232Th respectively in the plant samples. The results obtained for heavy metal (elements) contents strongly indicated the adverse effect of bitumen on soil and plants as the values obtained showed that the soil cannot support plant growth and this were visual in many dying plants in the environment and farmlands.  The values obtained for natural radionuclide concentrations and heavy metal contents were higher than the values reported for several other locations while 40K values reported were higher than the world average values.