Inferring the chemical parameters for the dissolution of fluoride in groundwater

Geochemical study of groundwater from 58 selected fluoride rich areas in different parts of India that includes eight states indicates that: 1. These groundwaters are alkaline in pH (7.4-8.8) and their electrical conductivity varies from 530-2,680 muS/cm and flouride concentration from 1.7-6.1 mg/l. Presence of flouride-bearing minerals in the host rocks and their interaction with water is considered to be the main cause for flouride in groundwater. 2. The decomposition, dissociation and dissolution are the main chemical processes for the occurence of flouride in groundwater. During rock-water interaction, concentration of flouride in rock, aqueous ionic species and residence time of interaction, etc. are also important parameters. 3. This study indicates that 85% groundwater samples have EC: 1,000-2,000 muS/cm, pH: 7.5-8.5, and HCO3/Ca (epm ratio): 8.0-2.3. 4. The Ca and HCO3 contents of groundwater samples have shown good correlation with flouride.