A.S. Divya¹, V.S. Joji*¹ and Dipankar Saha²

¹Department of Marine Geology and Geophysics, School of Marine Sciences, Cochin University of Sci. and Tech., Cochin – 682 016 (KL), India

²CAWTM, MRIIRS, Central Ground Water Board, Ministry of Jal Shakti, Govt. of India, Faridabad–121001(HR) India

(*Corresponding Author, E-mail: jojivsdeepam@cusat.ac.in; Orcid id- 0009-0006-4701-2158)

Abstract

The high fluoride concentration in groundwater, exceeding 1.5 mg/L in parts of Dharmapuri, Krishnagiri, Salem, and Vellore districts, poses significant public health concern. Notably, Dharmapuri district exhibits the highest fluoride levels in Tamil Nadu. Recent studies revealed that many groundwater samples from Dharmapuri district of Tamil Nadu are affected by fluoride contamination. To investigate the spatial distribution of fluoride in groundwater, hydrogeochemistry and the effect on human health, 66 water samples collected from Pullamapatti Watershed (PW) were analyzed. The samples collected from different groundwater extraction structures were analyzed for pH, EC, TDS, total hardness, alkalinity and major ions utilizing standard methods. In the case of cations, Na+ is the most prevalent, followed by Mg2+, Ca2+, and K+ and the major anions in the groundwater are ordered by proportional abundance as follows: Chloride > Bicarbonate > Sulfate > Nitrate > Fluoride. The investigation using Gibbs analysis revealed that the chief cause of groundwater contamination is rock-water interaction. Furthermore, Fluoride human health risk assessment for various age groups was performed by estimating the total hazard Index for all the collected samples. It is found that 75.7% of infants, 50% of children, and 34.28% of adults are affected by fluoride contaminated water.

Keywords: Hazard Quotient, Fluorosis, Groundwater contamination, Aquifer, Hydrochemistry