Title: Natural radionuclides in Niger delta sedimentary organic rock samples

Authors: Akinsehinwa Akinlua; Josephine Omolara Fagbemi; F.O.I. Asubiojo; Nelson Torto

Addresses: Fossil Fuels and Environmental Geochemistry Group, Department of Chemistry, Obafemi Awolowo University, Ile-Ife, Nigeria ' Department of Chemistry, Obafemi Awolowo University, Ile-Ife, Nigeria ' Department of Chemistry, Obafemi Awolowo University, Ile-Ife, Nigeria ' Department of Chemistry, Rhodes University, Grahamstown, South Africa

Abstract: Thirty sedimentary organic rock samples were collected at different depths from three oil wells in the Niger Delta. The natural radionuclides in the samples were measured in order to determine their geochemical significance and radiological effect. The radionuclides were measured using gamma spectrometric technique. Natural occurring radionuclides identified were uranium, thorium and potassium. The average activity concentrations obtained were 2441.65±753.00, 28.31±8.83 and 14.49±4.46 Bq/kg for ⁴⁰K, ²³²Th and ²³⁸U, respectively. The equivalent doses calculated from activity concentrations of the radionuclides ranged from 0.69-1.25, 0.89-1.18, and 1.19-1.38 mSv/year for Meji, Malu and Mefa oil wells, respectively. These values are slightly higher than the normal background radiation value of 1 mSv/year. The background radiation of ⁴⁰K detected in these samples was high, the absorbed dose rate and equivalent dose was slightly high, which could pose intrinsically radiological health hazard because of their cumulative radiological effect in the environment.

Keywords: natural radionuclides; sedimentary rock; oil wells; Niger delta; absorbed dose rate; low radiation; background radiation; radiological health hazards; cumulative effect.

DOI: 10.1504/IJLR.2014.060908

International Journal of Low Radiation, 2014 Vol.9 No.3, pp.169 - 180

Received: 19 Nov 2012
Accepted: 16 Apr 2013
Published online: 22 Oct 2014 *

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