Groundwater Quality Assessment and Human Health Risk Evaluation of Nitrate Contamination in a Mechanic Workshop Environment

Although groundwater remains a primary source of drinking water in many rapidly urbanizing regions, it is increasingly threatened by contamination from informal industrial activities. This study presents an integrated assessment of groundwater quality and associated human health risks in Awka South Local Government Area, Anambra State, Nigeria, with a particular focus on boreholes located near automobile mechanic workshop clusters. Most physicochemical parameters, including electrical conductivity, total dissolved solids, salinity, and heavy metals, were within acceptable limits for drinking water. However, the groundwater exhibited a strongly acidic pH (4.78) and elevated nitrate concentration (70 mg/L), exceeding the recommended guidelines. Risk assessment revealed that nitrate poses significant non-carcinogenic health risks, with hazard quotient values greater than one for both adults and children, indicating unsafe exposure levels. The acidic condition further suggests an increased potential for metal mobility and secondary contamination. Although heavy metal concentrations were generally low, the combined influence of hydrochemical conditions and nitrate contamination compromises water safety. The findings highlight the impact of anthropogenic activities on groundwater quality, particularly from automobile mechanic operations, and emphasize the need for integrated monitoring, improved waste management, and appropriate water treatment strategies.