Vulnerability of intensively-exploited hard-rock aquifers to fluoride contamination in India: impact of global change

Abstract : A geochemical study was conducted to obtain a comprehensive understanding of fluoride concentration increase in groundwater from a crystalline (hard-rock) aquifer in a small Indian agricultural watershed, where groundwater is intensively abstracted for paddy irrigation. A reactive1-D geochemical model using PHREEQC was used to reproduce fluoride concentrations under rice paddies taking into account evaporation and return flow related to paddies and water-rock interactions processes, namely dissolution of biotite, allanite and fluoro-apatite as well as absorption onto Al and Fe-hydroxides. This model can be applied to evaluate vulnerability to high fluoride concentration for several land use and climate change scenarios.