Assessment of Naturally Occurring Potentially Harmful Elements in Groundwater and Surface Water and Their Possible Health Impacts on Humans: A Case Study from Beaufort West, Western Cape Province, South Africa

The objective of this study was to assess the geochemical composition of both groundwater and surface water in the Beaufort West region, South Africa, to quantify concentration levels of naturally occurring potentially harmful elements (NOPHEs) and evaluate their associated human health risks. Twenty-three water samples were collected, including 19 from groundwater (windpump) and 4 from surface water (river and dam) sources. The results revealed that several NOPHEs in both groundwater and surface water exceeded the World Health Organisation (WHO) and South African National Standards (SANS) guideline limits. In groundwater, elevated concentrations were observed for Zn (508 mg/L), Na+ (392 mg/L), K+ (14.4 mg/L), U (35.9 mg/L), Fe (0.4 mg/L), SO₄2⁻ (615 mg/L), Cl⁻ (538 mg/L), NO₃⁻ (95 mg/L), and F⁻ (3 mg/L), while surface water samples showed elevated Na+ (388 mg/L), Fe (1.1 mg/L), SO₄2⁻ (744 mg/L), Cl⁻ (558 mg/L), Zn (10.6 mg/L), and Mg2+ (75.3 mg/L). Multivariate statistical analyses (Spearman correlation, PCA, and HCA) revealed that NOPHE enrichment in groundwater is primarily controlled by local bedrock geology through water–rock interactions, with additional contributions from anthropogenic sources, including agriculture and waste discharge. The dominant hydrochemical facies, Na-Cl–SO₄-HCO₃ and Na-Ca-Mg-HCO₃-SO₄ in groundwater, and Ca-Mg-Na-HCO₃ in surface water, indicate processes of mineral dissolution, evaporation, and ion exchange. Health risk assessment revealed that non-carcinogenic risks (HQ > 1) from NO₃⁻, F⁻, Fe, As, and U exceeded safe limits for children, while NO₃⁻, F⁻, and Fe posed risks to adults and infants. Carcinogenic risk from As and U (CR > 1 × 10⁻4) also exceeded acceptable limits in most groundwater samples, particularly for children. Overall, the findings highlight significant groundwater quality concerns in Beaufort West. Regular water monitoring, treatment interventions, and sustainable land-use management are recommended to reduce exposure risks and protect public health.