Discerning The Geological And Geochemical Controls On Mobilization Of Fluoride In Groundwater And Assessing Associated Human Health Hazards Of A Fluoride Endemic District Of West Bengal, India

Abstract

Fluoride is one of the persistent groundwater pollutants that affect a large number of people across the globe. Consumption of groundwater with fluoride content above the WHO permissible limits can be of several types, including crippling, fluorosis. Fluoride contamination is an endemic problem of the district of Birbhum, West Bengal. A substantial population of the district consumes groundwater having fluoride above the statutory levels which makes it vulnerable to fluorosis. Geological, geochemical, and structural controls on the buildup and mobilization of fluoride in the groundwater were investigated. In addition, health hazards, arising out of consumption of fluoride laden groundwater, were evaluated through the calculation of the Total Hazard Quotient (THQ). This was further used to delineate zones. Dominant alkaline water conditions, along with high bicarbonate content, promote the dissolution of fluoride from fluoride-bearing minerals, in addition to aiding the release of fluoride through substitution. Increased rock-water interaction and low hydraulic conductivity further exacerbate the condition. A strong control of lineaments on the mobilization of fluoride could be inferred through geospatial analysis.