Radioassay of prominent Nigerian fossil fuels using gamma and TXRF spectroscopy

Radioassay of the established fossil fuels found in Nigeria has been carried out using a combination of gamma and total reflection X-ray fluorescence (TXRF) spectrometry. Results indicate that of the three fossils, bitumen with a total of 61.54±23.93 Bq kg−1 has the highest natural radioactivity. This is followed by coal with a total of 30.48±5.29 Bq kg−1. The mean natural radioactivity 0.06±0.025 Bq kg−1 measured in the crude oil samples is quite low compared to those determined for the other two fossils. Of the three fossil fuels, coal displayed the highest potential of containing most of the elements analyzed for while bitumen and crude oil indicate As, Ca, Cr, Fe, K, Mn, Ti, V and Cr, Fe, Mn and V, respectively, at detectable levels. Most of these elements except As, Co, Cr and V are crustal or lithophilic and are therefore expected to be present at higher concentrations in coal and bitumen samples in view of their higher soil content. The elements Ni, Cu, Zn, Pb and S are fingerprint elements for crude oil and are therefore necessary to be detected in such and related bitumen samples.