Fluoride health risks and index-based scaling and corrosiveness potency assessment of groundwater in a peri-urban area in Ghana using multimethod techniques

In Ghana, the health risk associated with F⁻ in groundwater has been well researched, but mostly in the northern parts, with very scant information in the southern parts. The corrosiveness and scaling evaluations in Ghana are generally not prioritized in groundwater quality assessments. These affect the country and other developing countries, in the scope of groundwater monitoring and management practices towards the attainment of Sustainable Development Goals (SDGs) 6 and 9. To add to the ongoing discussions on these global issues of groundwater, the study assesses the F⁻ health risk, corrosiveness and scaling potential of groundwater using hazard quotient (HQ) and index (HI) of F⁻, Langelier saturation index (LSI), Puckorius scaling index (PSI), Ryznar stability index (RSI), Larson-Skold index (L-SI), and aggressive index (AI) for corrosiveness and scaling evaluations. These were complemented by factor analysis, predictive modeling, sensitivity analysis, and spatial mapping. The Fluoride Risk Index (FRI) indicates that 17% and 24% of the area have high and moderate F⁻ risks, respectively. The Hazard quotient (HQ) and hazard indices (HI) are the same and reveal 59% and 48% of the area is at F⁻ health risk for children and adults, respectively. The dissolution of biotite, fluorapatite, and cryolite is the most likely source of the F⁻. The prediction model, however, performed poorly and revealed no predictors of the F⁻ in the area. Fluoride health risk zones are within the Asuotwene and Tenbibian catchments. The LSI, RSI, RSC, CSMR, and AI indicate that the groundwater in the area has corrosive potency. The L-SI indicated the highest scaling potential (92%). The prediction models for LSI, L-SI, RSI, AI, and PSI performed well with R² values > 0.75. Calcium, pH, and HCO₃⁻ are the most sensitive parameters to these indices, except for CSMR. The metallic water supply, storage, and plumbing systems within Asuotwene, Tenbibian, Osiem, and Kukuruntumi would require regular monitoring, maintenance, and replacement to ensure the safe and sustainable use of the groundwater within these catchments.