Evaluation of aqueous geochemistry of fluoride enriched groundwater

Abstract

High fluoride (F−) groundwater causes fluorosis which might at severe stages lead to deformation of bones, bilateral lameness. The concentration of F− ranged from 0.4 to 4.8 mg/L. This study suggests that high HCO3− and Na+ in alkaline medium along with water–rock interaction plays important role in enrichment of F− in groundwater. Na-HCO3 is the dominant water type followed by Ca-HCO3 suggesting dominance of Na+, Ca2+ and HCO3− ions in groundwater. Factor analysis of water quality parameters suggests that four principal components account for 74.66% of total variance in the dataset. Factor 1 shows higher positive loading for pH, HCO3− negative loading for F−, Ca2+, SO42− depicting ion-exchange and HCO3 dominant water type responsible for F enrichment in groundwater. Saturation index for selected minerals suggests that most of the samples are oversaturated with calcite and undersaturated with fluorite. Calcite precipitation leads to the removal of Ca2+ from solution thus allowing more fluorite to dissolve. These released Ca2+ ions combine with CO32− ions to further enhance the precipitation of CaCO3.