Appraising groundwater/surface water quality and health risk assessment from nitrate contamination in the urban city of Bafoussam, Cameroon, Central Africa

• More than 80% of the population depend mainly on groundwater and surface water for drinking and domestic purposes • Rock-water interactions and anthropogenic activities are the two main factors controlling water chemistry • 16% of the samples had nitrate content above WHO recommended standards for drinking water • More than 80% of groundwater had high microbial loads • Pollution was found to be concentrated in the densely populated parts of the city Urbanization poses a significant threat to the major cities of developing countries, leading to increased pressure on the demand and quality of potable water. Groundwater and surface water are principally relied on due to an inadequate municipal water supply. This study evaluated the quality and contamination of groundwater and surface water (n = 50) in the urban city of Bafoussam. The abundance of the ions followed the trend; Na + >Ca 2+ >Mg 2+ >K + (mg/l) for cations, and HCO 3 − >NO 3 − >Cl − >SO 4 2− >NO 2 − >F − (mg/l) for anions. The main hydrogeochemical facies included Ca-Mg-HCO 3 , Na-K-HCO 3 , Na-K-Cl, and Ca-Mg-Cl-SO 4 , indicating that rock-water interaction, mineral weathering, and ion exchange were the primary hydrogeochemical processes influencing the water chemistry in the area. Results from WQI indicated that all the water was of good quality. PCA, HCA, and spatial element distribution maps revealed the presence of NO 3 − pollution in densely populated areas with NO 3 − concentrations as high as 167 mg/l in some water samples. NPI classified about 12% of water as having significant nitrate pollution. High loads of Escherichia Coli, Enterococci, and Total Coliforms were observed in 80% of the water samples, confirming anthropogenic pollution mainly from point sources such as leachates from pit toilets, waste dump sites, poultry farms, piggeries, and sewage disposal. The health hazard of NO 3 − estimated using the USEPA HHRA model showed CDI level ranges of 0-0.76 for adults and 0-11 for children. The Hazard quotient (HQ NO3 ) was >1, showing about 30% of the younger population is at higher risk of chronic toxicity from excess nitrate ingestion.