Seasonal Variations in Trace Metals and Anions in Surface Water of the Vaal River, South Africa: Implications for Human Health Risk Assessment

Abstract

This study monitored seasonal variations of metals and anions in the Vaal River and assessed health risks from water use. Water samples were collected over four seasons from locations spanning about 180 km and analyzed for physical and chemical properties. Concentrations of Fe, Al, and Mn exceeded World Health Organization (WHO) and South African National Standards (SANS) limits. Electrical Conductivity (EC) exceeded standards in all seasons except autumn. One-way ANOVA indicated no significant differences over seasons except for Cu, while the Kruskal Wallis test showed significant variation in Br-, Cd, and Cr. Water Quality Index (WQI) ranged from 74.6 to 255.3, indicating water quality from good to very poor, with Al and Fe as major contributors to poor quality. Human health risk assessments revealed significant non-carcinogenic and carcinogenic risks for children at all sites, with Cr identified as the primary contributor to the estimated cancer risk.