Hydrogeochemical investigation and fluoride levels in lakes: a comprehensive health risk assessment.

Abstract

The study investigates the key hydrogeochemical relationships between salts and ions, their spatial distribution, sources of occurrence, and the non-malignant health effects associated with fluoride contamination risk in the lakes of Rajasthan, India, considering a cluster of 18 lakes. The findings highlight the significant influence of both anthropogenic activities and natural lithology on these lakes, which serve as crucial sources of potable and domestic water supply. Water quality parameters such as BOD, pH, Fe, Mn²⁺, PO₄^3-, F-, and HCO₃ exceeded the permissible limits set by the WHO. Correlation analysis revealed positive associations, whereas the dissemination of F^– resulted in low to moderate correlation at p < 0.005 with TDS (R² = 0.37), bicarbonate, HCO₃^– (R² = 0.42), EC (R² = 0.3654), Na⁺ (R² = 0.39), Ca²⁺ (R² = 0.49), TH (R² = 0.29), Mg²⁺ (R² = 0.45), Al³⁺ (R² = 0.42). The piper diagram showed that the lakes exhibit an alkaline nature, with Ca–HCO3 (68.5%) and Ca–Mg–HCO3 (17.5%) as the dominant hydrogeochemical compositions with high pH, high bicarbonate ions, and elevated levels of Mg²⁺ and SO₄^2- ions. The values of HQI are ranging from 0.34 to 24.67 for infants (age 0–2 years), from 0.22 to 16.67 for children (age 3–11 years), from 0.18 to 12.675 for teenagers (age 12–19 years) and from 0.14 to 11.34 for adults (age 20–65 years). The study area, including regions like Udaipur, Jodhpur, Alwar, Ajmer, and Udaipur, showed that approximately 52% of the population falls within Category F2 (Fluoride concentrations between 0.5 mg/L and 1.5 mg/L).