Evaluation of groundwater contamination for fluoride and nitrate in Nellore Urban Province, Southern India: a special emphasis on human health risk assessment (HHRA)

Abstract

Groundwater pollution with fluoride and nitrate is one of the most serious issues in coastal regions. Thirty-nine groundwater samples were collected in the current research region and tested for PH, TDS, and EC. Thirty-nine groundwater samples were collected in the current research region and tested for PH, TDS, EC and cations, anions, and hardness. The elevated parameters are EC, PH, TDS, and nitrates. The fluoride fell in the permissible limit in Nellore urban area, nitrate and fluoride exposure heath risk calculated by using the US EPA method. From that, the total hazard index (THI) was calculated. The fluoride total hazard index value ranges from 0.15 to 0.95 and that of average 0.45, which fell below < 1, hence no significance on children, women, and men. The nitrate is falling in excess in groundwater. The ranges are 35 mg/l to 72 mg/l, and adverse value is 47.8 mg/l. The total hazard index (THI) of nitrates fell at > 1, which indicates a harmful for the human health. The computed THI affected percentage is the children (100%), women (95%), and men (30%). The nitrate was released in water due to the industrial discharge, septic tanks, manure pools, sewer system, and rock–water interaction. The abundance of the cations and anions is Ca²⁺ > Na⁺ > Mg²⁺ > K⁺ and HCO₃⁻ > Cl⁻ > SO₄² > NO3 > F. The Gibbs diagram explains the source of the chemistry; hence, all samples fell in the rock–water interaction area.