Hydrochemical evolution, geospatial groundwater quality and potential health risks associated with intake of nitrate via drinking water: case of Gboko agricultural district, central Nigeria

Elevated nitrate concentration in groundwater used for domestic purposes can pose a health hazard to humans. This study is aimed at determining the hydrochemical characteristics, and evaluating nitrate contamination, and assessment of nitrate health risk in Gboko district, Nigeria. A total of 50 groundwater samples were collected from shallow wells and analyzed for various physicochemical parameters. Nitrate concentration ranged from 0.02 to 156.85 mg/l and a mean value of 26.50 mg/l, and 26% of the groundwater samples have concentration above the guideline value (50 mg/l) for drinking water. Nitrate sources in groundwater of the area included application of nitrogen-based fertilizer, sanitary facility, and sewage. Hazard quotient via oral ingestion (HQ oral ) for adult and children has mean values of 0.43 and 0.83 respectively while the hazard quotient via dermal exposure (HQ dermal ) has mean values of 0.002 and 0.0031 for adults and children respectively. Hazard index (HI) for adults ranged from 0.0003 to 2.4317 with a mean of 0.4419, and HI for children ranged from 0.0006 to 4.592 with a mean value of 0.8344. The results showed that children are at more risk than adults in consuming nitrate contaminated groundwater. Proper groundwater planning, development, and management are required to ensure the supply of potable groundwater.