V3I2P43

Toxic Metal Contamination and Drinking-Water Safety in Domestic Borehole Water of Opukuma , Bayelsa State, Nigeria

Iwalokun Joseph Adebowale^1*, Paaru moses and Richard Otayoor Abalist²

Abstract

This study evaluated the physicochemical characteristics and heavy metal contamination of groundwater from five boreholes in Opokuma, Kolokuma/Opokuma LGA, Bayelsa State, Nigeria, to assess drinking-water suitability and potential health risks. In-situ parameters showed low mineralization (EC: 30–44 µS/cm; TDS: 16–22 mg/L) and slightly acidic conditions (pH: 5.74–6.30). Heavy metals revealed severe contamination: cadmium ranged from 0.073 ± 0.001 to 0.957 ± 0.006 mg/L and lead from 0.599 ± 0.001 to 1.777 ± 0.001 mg/L, far exceeding WHO limits (0.003 and 0.01 mg/L, respectively). Arsenic exceeded guidelines at two sites (0.016 ± 0.001 and 0.160 ± 0.002 mg/L), while nickel marginally exceeded the limit at one site (0.084 ± 0.001 mg/L). Iron was extremely elevated across all boreholes (13.09–22.17 mg/L). Chromium, copper, zinc and mercury were within guideline limits. Index-based assessments classified all boreholes as unsuitable for drinking (WQI: 4557–20123; HPI: 4558–20128). Non-carcinogenic health risk was substantial (HI: 12.26–34.91), driven mainly by Cd and Pb. Multivariate analyses indicated combined geogenic and localized anthropogenic controls on metal distribution. Untreated groundwater in Opokuma poses serious public health risks due to toxic metal contamination. It is recommended that routine monitoring, provision of alternative safe water sources, and point-of-use metal removal technologies be implemented to mitigate exposure.

Keywords:

Groundwater quality; Heavy metals; Drinking-water safety; Health risk assessment; Water Quality Index (WQI); Heavy Metal Pollution Index (HPI).