FLUOROSIS

The problem of high fluoride in groundwater has now become one of the most important toxicological and geoenvironmental issues in India. During the last 3 decades high fluoride concentration in water resources resulting in the disease called "Fluorosis" is being highlighted considerably throughout the world. The dominant rock types of the region are biotite hornblende gneiss and Charnockite. In the places of rock dominance with apatite especially in pegmatite, granite and charnockite, the fluoride concentrations are higher. So the hydrogeochemistry of the groundwater in these two dominant aquifers of the region indicate the behavior of the fluoride ion in them. Geochemical studies reveal the variations in the (H4SiO4/HCO3), (F/Alkali) and (F/Ca+Mg) molal ratios and the ionic strength of the groundwater in the aquifers. The correlation and statistical analysis show that the concentration of ions in the BHG is lesser due to the frequent flushing take place there. Fluoride concentration is generally lower than prescribed limit in most of the groundwater samples, except few areas where the F concentration is >1.5 ppm. In some places groundwater needs fluoridation to enhance fluoride levels in groundwater. The study reveals that the fluoride concentration is controlled by the lithology of the area.