Integrated Water Quality and Human Health Risk Assessment in Diobu, Port Harcourt, Rivers State, Nigeria

Abstract

Urban water resources in the Niger Delta are increasingly impacted by rapid urbanisation, inadequate waste management, and diffuse anthropogenic inputs. This study evaluated the integrated physicochemical quality and non-carcinogenic human health risks associated with domestic water sources in Diobu, Port Harcourt, Rivers State, Nigeria. Water samples from surface water, borehole groundwater, and harvested rainwater were collected during the dry and wet seasons and analysed using standard methods, including in situ measurements and flame Atomic Absorption Spectrophotometry. The pH ranged from 5.6 to 6.8, indicating slightly acidic conditions, while electrical conductivity (54–268 µS/cm) and total dissolved solids (33–176 mg/L) remained within World Health Organisation guideline limits. Turbidity was highest in surface waters, with values up to 5.2 NTU. Iron concentrations (0.48–0.82 mg/L) exceeded the guideline value of 0.30 mg/L at several locations, while lead (0.010–0.021 mg/L) and cadmium (0.002–0.006 mg/L) showed localised exceedances. Chromium, nickel, zinc, and copper occurred at comparatively lower concentrations below their respective guideline thresholds. Seasonal assessment revealed significantly higher concentrations of iron, lead, cadmium, and nickel during the dry season compared to the wet season (p < 0.05). Estimated daily intake values for all metals were below reference doses for both adults and children. Individual hazard quotient values were less than unity; however, cumulative hazard index values indicated acceptable non-carcinogenic risk for adults (HI = 0.62) but potential health concern for children (HI = 1.30), reflecting increased vulnerability due to combined metal exposure. Although overall water quality was moderate, the findings underscore the need for routine monitoring and improved urban water management to minimise long-term health risks, particularly for children in densely populated Niger Delta communities.