Groundwater Geochemistry in the Southeastern Part of Anantapur District, Andhra Pradesh, with Special Reference to Fluoride Distribution and Its Impact on Health.

Groundwater is the major water-source for drinking and irrigation in drought-prone southeastern part of Anantapur District, Andhra Pradesh (India). Geochemically, the groundwater is characterized by alkaline nature, higher contents of Na+ over K+, Ca2+ over Mg2+ and Cl- over NO3- more or less equal amounts of HCO3- and SO4(2-), and fluoride 0.5 to 5.51 mg/L, that is ~2-5 times over the W.H.O. (2004) prescribed limit of 1.5 mg/L for drinking. Due to high F in water, this region is severely affected by endemic fluorosis. High fluoride content in groundwater is attributed to release of F- into water from F-bearing rocks in this tropical region during their weathering and partial evaporation of such water. Use of this groundwater with high F- for drinking and irrigation for dry crops led to many health problems, viz. dental and skeletal-fluorosis, and deformation of bones, manifested in both children and adults. This calls for effective regional-scale defluoridation of water in this part to bring to permissible limit prior to its use, besides adoption of methods like rainwater harvesting.