Determination of radionuclide concentration of landfill at Eliozu, Port Harcourt, Rivers State

Abstract

A survey of the radionuclide concentration from landfill around Eliozu in Port- Harcourt Area of River State was carried out. This study assessed the level of terrestrial gamma radiation and associated dose rates from the naturally occurring radionuclides; ²³²Th, ²³⁸U and ⁴⁰K. 10 soil and 10 water samples collected from the respective reclaimed part of the Eliozu landfill were analyzed using the gamma-ray spectrometry NaI (Tl) detector system. The mean activity concentration for soil was found to be 27.41 ± 9.97 Bq/kg for ²³⁸U, 19.27 ± 8.14 Bq/Kg for ²³²Th and 326.08 ± 66.74 Bq/Kg for ⁴⁰K.The average specific activity concentration obtained for ²³⁸U, ²³²Th, ⁴⁰K for the water samples were 7.92 ± 2.69 Bq/l, 6.96 ± 2.37 Bq/l and 24.77 ± 8.33 Bq/l. Absorbed dose rates in air outdoors were calculated to be between the range of 23.53 nGy.h⁻¹ and 50.39 nGy.h⁻¹ with a mean of 38.17 ±12.45 nGy.h⁻¹ for soil and between the range of 6.62 nGy.h⁻¹ and 10.71 nGy.h⁻¹ with a mean9.03±3.07 nGy.h⁻¹ for water. This value is lesser than the world-averaged of 55 nGy.h⁻¹for soil. Inhabitants around the landfill are subjected to equivalent radiation exposure (effective dose rate) ranging between 0.2061 and 0.4414 mSv.y⁻¹ with a mean of 0.3344±0.1091 mSv.y⁻¹ and ranging between 0.0580 and 0.0938 mSv.y⁻¹ with a mean of 0.0791±0.0269 mSv.y⁻¹ for soil and water. The results comparable to those reported for environment in Nigeria and the World is relatively high due to the presence of medical wastes co-disposed with other wastes in these areas. The results indicated that the observed radiation dose of the terrestrial soils and water from Eliozu reclaimed landfill is minimal and seem to have no high exposure for either inhabitant in and around the landfills.

Keywords: Absorbed dose, effective dose, natural radioactivity, medical waste, landfill, γ-ray spectrometry