This study investigates the water quality of surface and groundwater sources in Manoka Island and the Wouri estuary (Youpwé), areas significantly impacted by urbanization, industrial activities, and agriculture. Physicochemical parameters (pH, EC, TDS, temperature, and salinity) were measured on-site, and 50 samples (13 boreholes, 29 hand-dug wells, and 8 surface water) were analyzed for major ions using inductively coupled plasma mass spectrometry (ICP-MS). Additionally, 30 samples were tested for biological contaminants, specifically Escherichia coli and Salmonella, using the membrane filtration techniques. Results showed pH between 6.70 and 7.20, EC ranging from 7 to 29,400 μS/cm, and TDS between 4 and 14,100 mg/L. Dominant water types were Na-Cl (76%), Mixed Ca-Mg-Cl (10%), and Ca-Cl (14%). The water chemistry was mainly influenced by precipitation (56%), rock weathering (28%), and evaporation (16%). While most parameters met WHO guidelines for drinking water quality, high TDS, EC, ammonium, potassium, and nitrate levels were concerning. Water Quality Index (WQI) classified 28% of samples as excellent, but 24% as unsuitable for drinking. Microbiological analysis revealed contamination, with E. coli present in 26.7% of samples, Salmonella in 23.3%, and both pathogens in 13.3%. Hand-dug wells contributed to 70% of pathogen-positive samples, highlighting urgent water quality and safety concerns.

 

Key words: Geochemistry, water quality, physicochemical parameters, Wouri estuary.