Radioactivity level and toxic elemental concentration in groundwater at Dei-Dei and Kubwa areas of Abuja, north-central Nigeria

Abstract

Abstract The activity concentrations of uranium and toxic elements in Dei-Dei borehole, Kubwa borehole, Water Board and hand-dug well water samples in Abuja area were measured using inductively coupled plasma mass spectrometry (ICP-MS) system. The results obtained were used to calculate human radiological risk over lifetime consumption by the inhabitants in the area. The activity concentrations of 238 U in all the water supplies for drinking ranges from 0.849 mBq L −1 to 2.699 mBq L −1 with the highest value of 2.699 mBq L −1 noted at Dei-Dei borehole whereas the lowest value of 0.849 mBq L −1 was noted in Kubwa borehole. The highest annual effective dose from natural 238 U in all the water samples was found in Dei-Dei borehole with a value of 8.9×10 −5 mSv y −1 whereas the lowest value was noted in Kubwa borehole with a value of 2.8×10 −5 mSv y −1 . The radiological risks for cancer mortality were found distinctly low, with the highest value of 1.01×10 −7 reported at Dei-Dei borehole compared to Kubwa borehole with a value of 3.01×10 −8 . The cancer morbidity risk was noted higher in Dei-Dei borehole with a value of 1.55×10 −7 whereas lower value of 4.88×10 −9 was reported in Kubwa borehole. The chemical toxicity risk of 238 U in drinking water over a lifetime consumption has a value of 0.006 μg kg −1 day −1 in Dei-Dei borehole whereas lower value of 0.002 μg kg −1 day −1 was found in Kubwa borehole. Measured lead (Pb) and chromium (Cr) concentrations reported higher in Water Board compared to Dei-Dei and Kubwa borehole samples. Significantly, this study inferred that the 238 U concentrations originate from granitic strata of the tectonic events in the area; thus, there was a trend of diffusion towards north to south and re-deposition towards Dei-Dei area.