Hydrogeochemical and multivariate statistical approaches to investigate the characteristics of groundwater quality in fluoride-enriched hard rock region in Tirupathur district of Tamil Nadu, India

Abstract

Fluoride pollution is a major issue worldwide, posing health risks such as dental and skeletal uorosis. This study was conducted in uoride 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 uoride was found to be 4 mg/L in the summer season in Vellakuttai region of Vaniyambadi taluk. The spatial distribution of uoride in groundwater during the monsoon season indicates that it is mostly leached from uoride-bearing minerals. The study aims to investigate the hydrogeochemical process and mechanism in uencing groundwater chemistry. The Piper and Gibbs diagrams has been carried out to illustrate the rock-water interaction and anthropogenic sources that contribute to the NaHCO 3 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 t indices, that con rms the variation in regional groundwater quality caused by various physicochemical characteristics. This study also aims to provide the con rmation of exploratory data analysis in groundwater quality using structural equation modeling. IntroductionGroundwater is the main source of fresh water in arid and semi-arid regions and is used for domestic, agricultural, and industrial activities. One-third of the worldwide population depends upon groundwater (Choubin et al. 2019;Li et al. 2021). Groundwater contamination majorly occurs due to anthropogenic and geogenic activities. The two inorganic ions arsenic and uoride in groundwater due to geogenic formation were identi ed as deleterious to human health. Of which uoride plays a dominant role than arsenic (Sajil Kumar et al. 2014). The range of uoride in groundwater, surface water, and seawater is 67 mg/L, < 0.1 mg/L, and 1.2-1.4 mg/L respectively (Yadav et al. 2019). According to World Health Organization, the permissible limit of uoride concentration in drinking water is not more than 1.5 mg/L (WHO 2022). The presence of uoride in drinking water reduces dental decay but an excessive level can lead to dental and skeletal uorosis, stooped backs, crooked hands and legs, blindness (Ayoob and Gupta 2006;Guissouma et al. 2017; Yadav et al. 2019). Due to activities such as the use of fertilizers in agricultural activity, industrial discharges, and municipal waste on land lls groundwater gets contaminated with uoride content. Other than anthropogenic activities uoride enters into groundwater through the dissolution of the hard rock region, which has compl...

Analysing the factors influencing groundwater quality using the Leachate Pollution Index (LPI), Heavy Metal Pollution Index (HPI), and Partial Least Squares - Structural Equation Modelling (PLS-SEM) in the vicinity of an open dumping yard in Saduperi, Vellore, Tamil Nadu, India.

“…The variables that are being observed consist of both dependent and independent datasets. SEM study establishes a direct relationship between independent and dependent variables (Nagaraj and Masilamani 2023). The previous studies made by (Huang et al 2019;Wang et al 2021) show the impact of climate change and vegetation on the temporal variability of hydrological parameters within a watershed and the correlation between water quality and land use types in the vicinity of a reservoir.…”