Hydrogeochemistry and fluoride contamination in the hard rock terrain of central Telangana, India: analyses of its spatial distribution and health risk

Groundwater is the primary source for drinking uses in the hard rock terrain of central Telangana, India, where most of the people rely on it for daily uses. Therefore, this study was carried out to comprehend the fluoride contamination and its associated health risk assessment to local dwellers. For this study, 54 groundwater samples were collected from bore wells and hand pumps in the study region and were analysed for fluoride and other physicochemical parameters. The results indicated by statistical mean values of Na+, Ca2+, Mg2+ and K+ are 182.14, 59.79, 23.90 and 3.74 mg/L, respectively, while HCO32-, Cl-, SO42- and NO3 are 236.1, 230.8, 167.7 and 81.9 mg/L, respectively. The fluoride concentration ranged from 0.8 to 4.2 mg/L, with a mean of 2.21 mg/L. Eighty-one percent of the groundwater samples exceeded the World Health Organization's water quality limit of 1.5 mg/L for fluoride. Piper trilinear diagram (PTD) signifies that groundwater quality in the study region is characterized by Na+-Cl-, Ca2+-Mg2+-Cl- and Na+-HCO3--Cl- hydrochemical water types. Gibbs diagrams indicate that all the major ion chemistry of the groundwater in the study region is controlled by rock-water interactions, while evaporation plays a minor role. The health risk assessment results revealed that the associated hazard quotient (HQ) for the age range of 6 to 12 months within about 100% of the study area exceeded the acceptable HQ limits of 1. Furthermore, the HQ for age categories 6-11 years, 11-16 years and 16-18 years within 96.2, 68.5 and 50%, respectively, of the study locations were larger than 1. Results also indicate that age group 6 to 12 months was most prone to health risks in the study region. Therefore, in the study region, people should be taken necessary actions to abolish the groundwater contamination to protect the local dweller's health.