Geophysical survey of groundwater potential and radioactivity assessment of soil depth lithology for drinking water-quality determination

Abstract

This research work evaluates the groundwater aquifer potential and radioactivity levels of the soil lithology depth of Agbor in Delta State Nigeria. Three geophysical surveys were conducted using vertical electrical sounding. The results show that the formation of the studied area has curve types KH, AA, and AH. Analysis of the layer thickness, resistivity, and transmissivity proposed specific layers to have the best aquifer thickness and depth with an average water table of 30.1 m. The assessment of the activity concentrations of 40K, 226Ra, and 232Th in the lithology was carried out using sodium iodide [Na(TI)] detector. The mean activity concentration of 40K, 226Ra, and 232Th are 254.0 ± 62.7 Bqkg− 1, 17.0 ± 5.7 Bqkg− 1, and 14.2 ± 5.0 Bqkg− 1, respectively. These values obtained were all below world permissible limits and compared well with the values reported in some part of the world. The estimated radiological risk parameters examined are radium equivalent (Raeq), annual gonadal equivalent dose (AGED), external hazard index (Hin), internal hazard index (Hex), representative index $$\left( {{I_\gamma }} \right),$$ absorbed dose rate (D), annual effective dose equivalent (AEDE), indoor and outdoor, and excess lifetime cancer risk (ELCR), and the mean values obtained were 56.9 mSvy− 1, 189.3 mSvy− 1, 0.2, 0.2, 0.4 Bqkg− 1, 27.6 $$~\eta Gy{h^{ - 1}},$$ 135.3 mSvy− 1, 33.8 µSvy− 1 and 0.12 × 10− 3, respectively, and are all below their recommended permissible limits. The radioactivity concentration levels obtained in the soil are low, and hence, the radioactivity level in the water aquifer will be low and drinking it will not cause any radiological health detriment.