NORMs distribution in coastal soils and sediments of River Yobe, north-eastern Nigeria: an evaluation of the potential radiological hazards

Abstract

A preliminary study which aimed to establish a reference data on naturally occurring radioactive materials (NORMs) for River Yobe has been conducted. Soil and sediment samples were collected along the coastal areas of the river and analyzed to determine the specific activities of NORMs such as ²³⁸U, ²³²Th and ⁴⁰K. Gamma spectrometry technique using NaI (Tl) detector was employed to determine the specific activities f the natural radionuclides. The mean activity concentration in the soil samples for ²³⁸U, ²³²Th and ⁴⁰K were found to be 23±1.5, 36±2.5 and 395±9.1Bq kg⁻¹ and for the sediment samples are 60±2.6, 45±3.6 and 324±6.8Bq kg⁻¹ respectively. These values, in some cases exceed the world reference values of 30, 35 and 400 Bq kg⁻¹ for ²³⁸U, ²³²Th and ⁴⁰K respectively. Parameters of radiological hazard, were also estimated based on specific activity of the radionuclides to assess the radiological impacts due to exposure on the users of the river. The results were found to be within the worldwide recommended safety limits.

Keywords: Annual effective dose, NORMs,²³⁸U.²³²Th.⁴⁰K. River Yobe