Nitrate Contamination in the Groundwater and Associated Human Health Risk Assessment for Gaya District, Bihar, India

The study pertains to nitrate concentration in groundwater resources of the Gaya district, Bihar, India and its related health risk to the local population. Groundwater serves as the principal source of drinking water in the area. 40 representative groundwater samples were collected and analyzed for nitrate and other water quality parameters. The concentration of Nitrate (NO₃^-) in the groundwater of Gaya district varied from 1.62 to 155.6 mg/L and exceeded the Bureau of Indian Standards (BIS) permissible limits for drinking water in 30% of the samples. The elevated nitrate levels were predominantly attributed to agricultural activities. To evaluate the human health risks associated with groundwater, Hazard Quotient for nitrate (HQ_nitrate) were calculated using the United States Environmental Protection Agency method. The mean HQ_nitrate values were estimated to be 1.03, 0.89 and 1.65 for the male, female and child populace, respectively depicting considerable risk to male and child populace. In 67.5% of the samples, HQ_nitrate for children exceeded the safety threshold of 1. The study advocates significant health risks, especially to children in many parts of Gaya district due to high concentrations of nitrate in the groundwater. Judicial use of nitrogen-based fertilizers is suggested to prevent further contamination of groundwater. The concentrations of nitrate showed significant spatial variations Nitrate concentrations exceeded the drinking water standards in 30% of samples. Nitrate in groundwater may be attributed to agricultural sources. Hazard Quotients indicated substantial health risks, especially impacting children.