Fluoride enrichment in groundwater and its association with other chemical ingredients using GIS in the Arjunanadi River basin, Southern India: Implications from improved water quality index and health risk assessment

The Sustainable Development Goal (SDG) 6 declares that water and hygiene are available for everyone. In the Arjunanadi River basin of southern India, 94 geo-labelled water samples are gathered from open and bore wells. Quality variables such TDS, pH, EC, Ca2+, Mg2+, Na+, K+, HCO3- , Cl- NO3- SO42- and F- are tested. The pH ranges from 7.12 to 8.28 with an average of 7.59. None of the samples exceed the acceptable limits. The fluoride concentration ranges from 0.1 mg/L to 2.5 mg/L with the mean value of 1.13 mg/L. The Piper diagram shows that the predominant (58%) water samples have secondary salinity followed by 21% (n=20) of samples have primary salinity, and 11% (n=10) of samples have secondary alkalinity. In Gibbs diagram, almost all the samples fall in the rock-water interaction facies. Fluoride shows a negative correlation with pH, bicarbonate, calcium, nitrate, and sulphate and a positive correlation with EC, TDS, sodium, potassium and magnesium. Improved Water Quality Index (IWQI) shows that 60 samples (ca.599 km(2)) have good quality, and 34 samples (ca.537 km(2)) posses poor quality water for drinking throughout the study area. The fluoride distribution shows, 27 samples (ca.173 km(2)) exceed the values of 1.5 mg/L for drinking and 73 samples (ca.963 km(2)) are suitable for drinking. The fluoride-enriched water from 66% of samples are risk to infants, teens, and women, and 53% of samples are risk to men through the oral (drinking) and dermal (showering) pathways. This study suggests eco-friendly measures to enhance groundwater quality and assist the local community in sustainable groundwater management techniques to achieve sustainable development for betterment of the society with the help of government authorities.