Heavy Metals Concent...

Groundwater remains the primary source of drinking water in many Nigerian urban centres, yet its quality is increasingly threatened by rapid urbanisation and anthropogenic activities. This study assessed the concentration of selected heavy metals and evaluated the Heavy Metal Pollution Index (HPI) of groundwater sources in Aba metropolis, Abia State, Nigeria. A total of forty (40) borehole water samples were collected across four local government areas: Aba North, Aba South, Osisioma Ngwa, and Obingwa, during both the dry and wet seasons. Samples were analysed for iron (Fe), copper (Cu), zinc (Zn), lead (Pb), cadmium (Cd), chromium (Cd) and cobalt (Co) using Atomic Absorption Spectrophotometry following standard APHA procedures. The results were compared with World Health Organization (WHO) guideline values, and groundwater suitability was evaluated using the HPI model. Findings revealed that Pb, Cu, and Zn concentrations across all sampling points were largely within WHO permissible limits, indicating minimal health risk from these metals. However, elevated iron concentrations exceeding the recommended limit (0.3 mg/L) were recorded in several locations, particularly in Osisioma and Obingwa LGAs, suggesting geogenic influence and possible infrastructure-related contributions. Heavy metals such as Cr, Cd and Co were not detected across all samples. The computed HPI values ranged from 0.001 to 0.10, far below the critical threshold of 100, confirming that groundwater in Aba metropolis is generally unpolluted by heavy metals. The study underscores the relative safety of groundwater in the area while highlighting the need for continuous monitoring to prevent future degradation.