Activity concentration and radiological impact assessment of 226Ra, 228Ra and 40K in drinking waters from (OML) 30, 58 and 61 oil fields and host communities in Niger Delta region of Nigeria

This paper presents the concentrations of naturally occurring radionuclides (226Ra, 228Ra and 40K) measured in hand dug wells, boreholes and river waters collected from three oil mineral leases (OML) 30, 58 & 61 oil and gas fields onshore of the Niger delta, using gamma spectroscopy. Fifty-four water samples from the three sources of drinking water supply were collected within the oil fields and host communities and three water samples from a control site. The results showed average activity concentrations of 226Ra, 228Ra and 40K as 8.9 ± 1.0, 8.1 ± 0.9 and 39.8 ± 3.3 respectively for hand dug wells, 4.4 ± 0.8, 4.6 ± 0.5 and 28.5 ± 3.0 for borehole water and 8.2 ± 1.0, 6.7 ± 0.7 and 32.1 ± 3.5 for river water respectively. These 226Ra, 228Ra and 40K average are well above the WHO permissible levels of 1.0, 0.1 and 10 BqL−1 respectively and also above the control values. Although the hazard indices calculated are still within their tolerable levels, the estimated committed effective dose due to intake of the sampled water for all the four age groups considered are far above the ICPR 0.1 mSvyr−1 maximum permissible limit. The result indicates some level of water pollution in the studied area.

► The concentration of natural radioactive series nuclides varies widely within oil fields and from one oil field to another in the OML30.
► The radionuclide activity concentrations in most water samples are higher than world average values.
► Calculated hazard indices and committed effective dose to assess the potential radiological health risk in samples are well above their permissible limit.
► The sources of water in these oil fields have been polluted and may cause some health hazard to the public users.