Geochemical characterization and risk implications of groundwater for irrigation and drinking around the agrarian metropolis of southeastern Nigeria
摘要
This study examines the hydrochemical characteristics and health implications of groundwater in Abakaliki metropolis, southeastern Nigeria, where fractured shales of the Asu River Group form the main aquifer. The aim is to evaluate groundwater quality for drinking and irrigation purposes and assess potential health risks linked to trace metals. Twenty-four groundwater samples were analyzed using standard physicochemical methods, with results interpreted through water quality indices, hydrochemical facies classification, and health risk models. Arsenic (0.428–3.947 mg/L) and lead (0.001–0.05 mg/L) concentrations exceeded World Health Organization (WHO) limits, posing significant health risks, especially for vulnerable groups. Hydrochemical facies were dominated by alkaline earths over alkali metals and weak acids over strong acids, with ionic order: HCO3− + CO32− > Mg2+ > Na+ + K+ > Cl− > Ca2+ > SO42−. Pollution indices showed no severe contamination; however, the total hazard index indicated potential chronic toxicity, with arsenic and manganese as leading contributors (As > Mn > Cd > Pb > Zn > Fe > Cu > Ni). Irrigation suitability parameters, including sodium adsorption ratio (SAR) and magnesium adsorption ratio (MAR), suggested that most water sources are suitable for agriculture, though elevated MAR in some samples may impair soil structure and crop yields. The observed contamination reflects both natural geogenic inputs and anthropogenic influences, including agricultural runoff and poor waste disposal. In conclusion, while groundwater is largely adequate for irrigation, untreated consumption poses serious public health risks. Mitigation strategies, including water treatment, stricter waste management, and regular monitoring, are strongly recommended to safeguard safe groundwater use.