Groundwater Vulnerability and Health Risk Assessment of Heavy Metal Contamination in Ikot Abasi, Niger Delta, Nigeria

Abstract

Groundwater is the main source of domestic water in the Niger Delta, but oil exploration and poor waste management have threatened its quality. Ikot Abasi, in Akwa Ibom State, is a hydrogeologically vulnerable coastal community with limited data on groundwater contamination. Groundwater samples were collected from four sites during wet and dry seasons and analyzed for 14 heavy metals and physicochemical parameters. Water Quality Index, Piper/Durov plots, PCA, HCA, and the U.S. EPA Human Health Risk Assessment model were applied. Aquifer vulnerability was assessed using DRASTIC-GIS. Concentrations of Pb (1.18–2.18 mg/L), Cd (0.083–0.110 mg/L), Ni (0.40–0.81 mg/L), Fe (1.99–4.01 mg/L), As (0.013–0.040 mg/L), and CN (0.050–0.160 mg/L) all exceeded WHO and SON limits. PCA identified two sources: PC1 (55%) linked to anthropogenic activities from artisanal refining and industry, and PC2 (23%) to geogenic weathering. HCA showed sites A and B as hotspots, while even the control site exceeded safe limits, indicating regional contaminant migration. Health risk assessment revealed high non-carcinogenic and carcinogenic risks for Pb, Cd, and As via ingestion. Groundwater in Ikot Abasi is unsafe for drinking due to combined anthropogenic and natural contamination. Urgent actions including monitoring, enforcement, alternative water supply, and remediation are recommended to protect public health and achieve SDG 3 and 6 in the community.