Hydrogeochemical and Multivariate statistical approaches to investigate the characteristics of groundwater quality in fluoride enriched hard rock region in Tirupathur district of Tamilnadu, India

Abstract

Abstract Fluoride pollution is a major issue worldwide, posing health risks such as dental and skeletal fluorosis. This study was conducted in fluoride enrichment hard rock regions of Vaniyambadi and Ambur talks in Tirupathur district, Tamilnadu. 480 groundwater samples were collected from May 2021 to April 2022 and grouped as Summer, Southwest monsoon, Northeast monsoon, and Winter. Maximum concentration of fluoride was found to be 4 mg/L in the summer season in Vellakuttai region of Vaniyambadi taluk. The spatial distribution of fluoride in groundwater during the monsoon season indicates that it is mostly leached from fluoride-bearing minerals. The study aims to investigate the hydrogeochemical process and mechanism influencing groundwater chemistry. The Piper and Gibbs diagrams has been carried out to illustrate the rock-water interaction and anthropogenic sources that contribute to the NaHCO3 and NaCl-type waters, respectively. Multivariate statistical analysis such HCA, PCA, MLR and SEM has been carried out to determine the groundwater quality. HCA analysis manifests the nature and sources of groundwater through Q-mode and R-mode analysis. PCA plays a role in eliminating the factors that associates with TDS for better development of the MLR model. The results of the MLR model provides higher accuracy in detecting the contamination factors associated with the environment and natural rocks. SEM revealed the goodness of fit indices, that confirms the variation in regional groundwater quality caused by various physicochemical characteristics. This study also aims to provide the confirmation of exploratory data analysis in groundwater quality using structural equation modeling.