Tectonic and radioactivity impacts of²³⁸U on groundwater-based drinking water at Gosa and Lugbe areas of Abuja, North Central Nigeria

Abstract

Tectonic contribution of activity level of 238 U in groundwater-based drinking water in Gosa and Lugbe areas of Abuja was measured using inductively coupled plasma mass spectrometry (ICP-MS). The highest activity level of 2736 μBq L −1 reported in Lugbe borehole, whereas the lowest value of 443 μBq L −1 reported at Gosa borehole. The inhabitants permanently used water from the boreholes for daily consumption. The group receives 5.55 × 10 −5 mSv of the annual collective effective dose due to 238 U in drinking water. The radiological risks of 238 U in the water samples were found to be low, typically in magnitude of 10 −7 with cancer mortality value of 1.03 × 10 −7 and morbidity value of 1.57 × 10 −7. The chemical toxicity risk of 238 U in drinking water over a lifetime consumption has a mean value of 4.0 × 10 −3 μg kg −1 day −1. It could be that the human risk due to 238 U content in groundwater supplies from ingestion may likely be the chemical toxicity of 238 U as a heavy metal rather than radiological risk. Significantly, Lugbe subsurface may have developed some fractions of granitic strata that contributed to the distribution of radioactive of 238 U in tectonically weak zones.