Fluoride distribution and groundwater hydrogeochemistry for drinking, domestic and irrigation in an area interfaced near Brahmaputra floodplain of North-Eastern India

Abstract Prevalence of fluoride mobilization and effect on groundwater quality at an area (Rangia) interfaced near Brahmaputra floodplain in North-Eastern region of India was examined for drinking, domestic and irrigation purposes. Groundwater samples were collected from tube-well during the pre-monsoon (PM), monsoon (M), and post-monsoon (POM) seasons and were further analyzed for various water quality parameters. Results showed that the pH of groundwater varies from almost neutral to slight alkaline condition. Further, EC, TDS, and total hardness results showed that almost all samples of three season comes within the permissible limit. In PM and POM, the concentration variation trend was observed as: HCO3− > Na+ > Ca2+ > Mg2+ > Cl− > SO42− > F− > K+ while in M season; HCO3− > Ca2+ > Na+ > Mg2+ > Cl− > SO42− > F− > K+ was observed. The base-exchange indices showed 93.3%, 73.3%, and 100% in PM, M, and POM, respectively, belonging to Na+ – HCO3− type. Other parameters, viz. water quality index, SAR value, RSC value, %Na, Kelly’s index, base-exchange and meteoric genesis indices and Gibbs ratio were also calculated. The results of three season groundwater quality parameters suggets that the maximum samples were found suitable for drinking, domestic and irrigation.