Determination of fluoride ion concentration in the salt pans of Vedaranyam, Nagapattinam district, India

This manuscript deals with the fluoride ion concentration, and electrical conductivity of various samples collected from Vedaranyam salt pan located at Nagapattinam District in India. It has an extent of 8800 acres, and lies at 10.3721° N latitude and 79.8503° E longitude. This salt pan is 90 km away from Thanjavur City and 43 km away from Nagapattinam. Pan samples were collected from Vedaranyam salt pan, among which 7 samples were saline water samples, and the remaining two were salt and pan soil samples. In this study, the amount of fluoride present in saline water samples, salt and pan soil of Vedaranyam salt pan were tested. In the brine samples, fluoride ion concentration gradually increased, and during crystallization it declined. This change in concentration of fluoride ion was aptly supported by electrical conductance values. The samples were collected in the summer season for eight days during April 2011. Analysis of fluoride in the samples were performed by Zirconyl-alizarin method. The concentration of fluoride was measured in the range of 0.8 ppm to 1.2 ppm which was available within the permissible limit of WHO recommendations. The decrease in the value of fluoride ion concentration in the salt from pan naturally protects humans from fluorosis. During crystallization considerable amount of fluoride (0.8 ppm) got settled into the pan soil. At the same time the available fluoride (1.0 ppm) is essential to prevent dental caries.