TAGRA 2025

This study presents an integrated geologic, petrographic and hydrogeochemical assessment of groundwater resources in the Waru area of Apo (FCT), Abuja, North-Central Nigeria. The objective was to characterize lithological units, evaluate groundwater chemistry, determine heavy metal concentrations and assess potential environmental and health implications. Field mapping and petrographic analyses established migmatite, granite gneiss, biotite gneiss and anatectic granite as the dominant basement lithologies, with deformation features such as joints, folds and quartz veins promoting groundwater circulation and enhancing aquifer vulnerability. Twenty-two groundwater samples obtained from streams, hand-dug wells and boreholes were analysed using Atomic Absorption Spectroscopy in order to quantify major cations, anions and trace metals. The concentrations of chromium (0.046–0.236 mg/L), cadmium (0.034–0.121 mg/L) and lead (0.003–0.023 mg/L) exceed World Health Organization (WHO) and Nigerian Standard for Drinking Water Quality statutory limits in several locations, indicating localized contamination. Hydrochemical evaluation revealed Na–SO4, and Na–Mg–SO₄ water types, which reflect dominant ion-exchange processes, sulphate dissolution and contributions from rock weathering. Application of Nemerow’s Pollution Index, Contamination Factor and Pollution Load Index indicated low-to-moderate pollution levels in most samples, although localized anomalies were observed particularly in areas proximal to abattoir and domestic waste zones. Elevated trace-metal values correlate with both geogenic release from basement rock weathering and anthropogenic inputs associated with abattoir effluent, agricultural practices and waste disposal. The health implications of observed Cr, Cd and Pb levels include carcinogenic and neurotoxic risks, especially for vulnerable populations dependent on shallow wells. The study underscores the need for improved groundwater monitoring, stricter regulation of abattoir waste disposal and the provision of safer potable-water alternatives in rapidly expanding peri-urban settlements of Abuja.