Chapter 21 - Geostatistical Studies for Evaluation of Fluoride Contamination in Part of Dharmapuri District, South India

Abstract

Accurate information on fluoride distribution in groundwater and geochemical knowledge with spatial information on geology and climate are necessary to understand the source/cause, type, and level of fluoride contamination. The research presented here aims to evaluate fluoride contamination through various statistical analyses in the Nallampalli Block of Tamil Nadu, India. The Nallampalli Block is mostly covered by hard-rock terrain and demarcated as one of the fluoride contaminated zones in Tamil Nadu. This is mainly due to the occurrence of various rock types containing fluoride-bearing minerals. The fluoride content of the groundwater originates from the dissolution of fluoride-bearing minerals from the bed rock. For research purposes, groundwater samples from 34 locations of the Nallampalli Block were analyzed for pre and postmonsoon seasons. The frequency analyses of seasonal spatial variations, variations in relation to other ions, and geological traverses were carried out to evaluate fluoride contamination in the study area. In the premonsoon period about 31% of the block represented a risk zone for high fluoride concentrations in groundwater, whereas in the postmonsoon period the risk zone area decreased to 29%. The results revealed that the nearly 50% of the groundwater samples had high fluoride contamination, which exceeds the permissible limit. The results of this study will provide a better understanding of high fluoride concentrations in groundwater in an attempt to develop management plans for creating deep bedrock groundwater. In addition, these results can be used for developing a cost-effective treatment for high fluoride groundwater.