Assessment of groundwater quality with special emphasis on fluoride contamination: a case study in Thar Desert, Pakistan

Abstract

Safe drinking water is inaccessible for about 1.1 billion people globally. This study scrutinizes the physicochemical characteristics, pollution sources, suitability for drinking and agricultural purposes, and associated health risks of groundwater in the Thar Desert of Pakistan. Groundwater collected from 15 villages was analyzed for physical and chemical contaminants We found that a significant number of sampled wells exceeded the World Health Organization’s (WHO) guidelines for various contaminants: F⁻ in 9 wells, Cl⁻ in 12 villages, SO₄²⁻ in 10 villages, and NO₃⁻ in 11 wells. The groundwater was predominantly classified as Na⁺ > Ca²⁺ > Mg²⁺ > K⁺ and Cl⁻ > SO₄²⁻ > HCO₃⁻ > NO₃⁻ > F⁻. Elevated concentrations of F⁻ (0.24–29.9 mg/L), Cl⁻ (20.6–8310 mg/L), NO₃⁻ (2.73–196 mg/L), and SO₄²⁻ (7.74–1158 mg/L) exceeded WHO safe limits in most samples. Factor analysis identified both geogenic and anthropogenic activities as significant contributors to the observed groundwater chemistry. Based on the water quality index, 87% of samples were unsuitable for drinking, and a non-carcinogenic risk assessment deemed groundwater from 80% of the sites unacceptable for adults and entirely unsuitable for infants. Our findings indicate a high risk of F⁻ and NO₃⁻ exposure for Thar Desert inhabitants. To ensure safe water consumption, we propose community-level implementation of treatment methods like distillation, reverse osmosis, and electrodialysis. Our study elucidates an urgent need for multi-stakeholder efforts toward sustainable water resource management and effective remediation. Implementing our proposed interventions and ongoing monitoring will be vital for protecting this vulnerable population's health and wellbeing.