Groundwater Quality, Contamination Sources, and Human Health Risk in Aba Industrial Area, Abia State

Groundwater is the primary water supply source for households in peri-industrial areas of Aba in Abia State within Nigeria's South East geopolitical zone, yet the proximity of major industrial activities involving chemical use, waste generation, and effluent disposal creates complex contamination risks that have not been comprehensively characterised in terms of spatial distribution, source attribution, or human health risk magnitude. This study investigates groundwater quality, contamination sources, and human health risk in the Aba industrial area using hydrogeochemical analysis, pollution source characterisation, and health risk assessment frameworks. Water samples from 48 boreholes and hand-dug wells distributed across industrial, peri-industrial, and control residential zones were collected and analysed for physicochemical parameters, major ions, heavy metals (lead, chromium, cadmium, arsenic, mercury), and microbiological indicators during dry and wet seasons. Multivariate statistical analysis including principal component analysis and hierarchical cluster analysis was applied to identify dominant hydrogeochemical processes and pollution source groupings. Health risk assessment followed the USEPA framework, computing carcinogenic and non-carcinogenic risk indices for exposure pathways of ingestion, dermal contact, and inhalation. Results identify three distinct contamination signatures in groundwater: tannery-associated chromium and organic pollution plumes centred on Ariaria; general industrial effluent contamination characterised by elevated biochemical oxygen demand and nitrate; and diffuse microbiological contamination linked to septic infrastructure failures across the study area. Carcinogenic risk from chromium ingestion exceeds acceptable levels for 34 percent of sampled wells. The study provides a spatially resolved contamination assessment that closes an important evidence gap for regulatory action. Keywords: groundwater quality, contamination, health risk, Aba, South East Nigeria.