Evaluation of groundwater quality using pollution index of groundwater (PIG) and non-carcinogenic health risk assessment in part of the Gangetic Basin

The aim of this study was to evaluate groundwater fitness for domestic and irrigational use in Unnao district of Uttar Pradesh, India. For this study, block wise (n = 16) groundwater samples were collected, and measured parameters were analyzed using the pollution index of groundwater (PIG), various irrigational indices, and graphical techniques. The results of this study suggested that most of the parameters were within the prescribed limits of WHO and BIS, excluding F− (0.4 to 2.6 mg L−1) and Fe2+ (0.1 to 1.7 mg L−1). Concentrations of total dissolved solids (TDS) were exceeded the desirable limit (> 500 mg L−1) in 43.75% of samples at some sites. The Gibbs plot revealed that groundwater chemistry was governed by rock-water interaction in the region, especially silicate weathering. The Piper plot suggested that Ca2+-HCO3− is dominant hydrochemical facies in the area followed by mixed Ca2+-Na+-HCO3−type, Na+-Cl− type, and Na+-HCO3− type. PIG evaluation revealed that the contribution of F− and Fe2+ in groundwater degradation is high in comparison to other elements in the region, about 18.75% samples showed low pollution, while about 6.25% samples shows moderate pollution, and 6.25% samples reflected high pollution. The human health risk (HHR) assessment finding suggested that children (mean: 1.36) are more vulnerable than adults (mean: 1.01). Sodium absorption ration (SAR), Residual sodium carbonate (RSC), and Permeability index (PI) indicated that most of the groundwater was suitable for irrigation, whereas, Magnesium hazard ration (MHR) and Potential salinity (PS) indices suggested that only 37.5% and 56.25% of the samples were suitable for irrigational use, respectively. This regional study would help in decision making for stakeholders and relevant authorities in the execution of groundwater management and remediation plans in the area.