Integrated Assessment of Water Quality and Public Health Risks in the Ossah River, Southeastern Nigeria: Implications For Sustainable Water Resource Management

Abstract

Rivers in developing countries face increasing pollution pressures from anthropogenic activities, threatening water quality and public health. This study presents an integrated assessment of water quality and associated health risks in the Ossah River, southeastern Nigeria, which serves as a critical water source for domestic, agricultural, and recreational purposes. Water samples were collected from six strategic locations along the river during both dry (January-February) and wet (July-August) seasons of 2023. Physicochemical parameters including pH, temperature, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids (TDS), turbidity, and conductivity were analyzed following standard methods. Heavy metals (Pb, Cd, Cr, Ni, Fe, Zn, Cu) and microbiological indicators (total coliform, fecal coliform, E. coli) were quantified. Water quality was evaluated using Water Quality Index (WQI), Heavy Metal Pollution Index (HPI), and comparison with WHO/Nigerian drinking water standards. Health risk assessment employed USEPA models calculating hazard quotients (HQ) and carcinogenic risks. Results revealed significant seasonal and spatial variability in water quality. Mean pH (6.8±0.4) was slightly acidic, DO (4.2±1.8 mg/L) indicated moderate pollution, while BOD (8.5±3.2 mg/L) and COD (24.3±8.6 mg/L) exceeded permissible limits. Heavy metal concentrations showed lead (0.085±0.032 mg/L) and cadmium (0.012±0.005 mg/L) exceeding WHO limits at multiple locations. Microbiological analysis revealed widespread fecal contamination with mean total coliform (2,450±1,280 MPN/100mL) and E. coli (580±340 MPN/100mL) substantially exceeding safe limits. Water Quality Index values ranged from 52-78, categorizing water as "poor" to "good" depending on location and season, with downstream sites showing greater deterioration. Heavy Metal Pollution Index (mean 68.5) indicated moderate to high pollution. Health risk assessment revealed non-carcinogenic hazard quotients >1 for children for lead and cadmium through ingestion pathway, indicating unacceptable risks. Carcinogenic risk from cadmium (2.8×10⁻⁴) exceeded acceptable threshold (10⁻⁶). Microbial contamination posed immediate health threats. Urgent interventions including pollution source control, wastewater treatment infrastructure, regular monitoring, and community awareness programs are recommended.