Natural radioactivity and trace metals in crude oils: implication for health |
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| Authors: | T R Ajayi N Torto P Tchokossa A Akinlua |
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| Institution: | (1) Department of Geology, Obafemi Awolowo University, Ile-Ife, Nigeria;(2) Department of Chemistry, University of Botswana, P/Bag UB 00704, Gaborone, Botswana;(3) Department of Physics, Obafemi Awolowo University, Ile-Ife, Nigeria;(4) Department of Chemistry, Obafemi Awolowo University, Ile-Ife, Nigeria |
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| Abstract: | Crude oil samples were collected from six different fields in the central Niger Delta in order to determine their natural
radioactivity and trace element contents, with the aim of assessing the radiological health implications and environmental
health hazard of the metals, and also to provide natural radioactivity baseline data that could be used for more comprehensive
future study in this respect. The activity concentrations of the radionuclides were measured using a well, accurately calibrated
and shielded vertical cryostat, Canberra coaxial high-purity germanium (HPGe) detector system, and the derived doses were
evaluated. The metal concentrations were determined by the graphite furnace atomic absorption spectroscopic (GFAAS) method.
The radionuclides identified with reliable regularity belong to the decay series of naturally occurring radionuclides headed
by 238U and 232Th along with the non-decay series radionuclide, 40K. The averaged activity concentrations obtained were 10.52 ± 0.03 Bq kg−1, 0.80 ± 0.37 Bq kg−1 and 0.17 ± 0.09 Bq kg−1 for 40K, 238U and 232Th, respectively. The equivalent doses were very low, ranging from 0.0028 to 0.012 mSv year−1 with a mean value of 0.0070 mSv year−1. The results obtained were low, and hence, the radioactivity content from the crude oils in the Niger delta oil province
of Nigeria do not constitute any health hazard to occupationally exposed workers, the public and the end user. The concentrations
of the elements (As, Cd, Co, Fe, Mn, Ni, Se and V) determined ranged from 0.73 to 202.90 ppb with an average of 74.35 ppb
for the oil samples analysed. The pattern of occurrence of each element agreed with the earlier studies from other parts of
the Niger Delta. It was obvious from this study and previous ones that the Niger Delta oils have low metal contents. However,
despite the low concentrations, they could still pose an intrinsic health hazard considering their cumulative effects in the
environment. Also, various studies on the impact of oil spillage and activities of oil exploration and production on organisms
in the immediate environment suggest this. |
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| Keywords: | Natural radioactivity Trace metals Dose Crude oil Niger Delta |
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