Groundwater resources for domestic and irrigation purposes in Melong (Littoral Region, Cameroon): Hydrogeochemical constraints

Groundwater is a valuable natural resource whose quality is threatened by natural and man-made pollutants. This study aims to perform a hydrochemical characterization of groundwater resources used for domestic and irrigational activities in Melong (Littoral Cameroon). Thus, 26 subsurface water samples were collected in the dry season (six sampling points) and rainy season (seven sampling points) of the years 2019 and 2020. Physical water quality parameters were measured on the field while ionic constituents and bacteriological parameters were determined in the laboratory. The main findings revealed that the pH of the water samples was slightly acidic to neutral, fluctuating from 5.3 to 7.1; electrical conductivity ranged from 0.03 to 0.33 µS/cm and turbidity varied from 0.5 to 33.7 NTU revealing that the water is weakly mineralized. The ionic constituents were such that Ca2+ > K+ > Mg2+ > Na+ for cationic constituents while anions appeared as HCO3-> NO3- >Cl- > PO43-. The major ions fell within the acceptable limits of World Health Organisation (WHO) drinking water standards. Bacteria indicators of faecal pollution were identified in all the water samples, including Enterobacteria, Escherichia coli, Streptococcus, Salmonella, Shigella, Staphylococcus and Vibrio. This indicates an exposure of water sources to unhygienic conditions that may place consumers at risk of water-borne diseases, hence necessitating basic treatment of the water before consumption.   Key words: Hydrochemistry, Melong, groundwater quality, bacteriological analysis, Littoral Cameroon.