A Study of Fluoride Contamination in the Aquifer Along ‘Sari Su’ and Zengimar Plains, West Azerbaijan, Iran - Implications for Sustainable Water Infrastructure

The hydrochemical behaviour and health implications of the aquifer contaminated by fluoride Along Sari Su (Yellow Water), northern West Azerbaijan province, Iran, is investigated in this paper. It uses, 60 water samples, including groundwater from deep and shallow wells, springs, qanats, and surface water, collected in October 2022. Fluoride concentrations ranged from 0.39 to 9.89 mg/L, with over 50% of samples exceeding the World Health Organization (WHO) guideline of 1.5 mg/L. Comparative analyses revealed that deep wells exhibited the highest fluoride levels, likely due to prolonged water–rock interactions and longer residence times within the aquifer. Hydrochemical analysis using bivariate plots revealed dominant processes including carbonate dissolution, ion exchange, and silicate weathering. Multivariate techniques, Factor Analysis, identified three latent factors: geogenic fluoride mobilisation, anthropogenic nitrate input, and secondary ion interactions. Temporal comparison with 2007 data showed an eightfold increase in fluoride intensity across monitored sites. Spatial mapping highlighted high-risk zones along the Sari Su River, where elevated fluoride coincided with vegetation stress. Health risk classification indicated that 33.3% of samples exceeded 4 mg/L, posing severe skeletal fluorosis risks. These findings underscore the vulnerability of groundwater systems and the need for targeted treatment and resilient infrastructure.