Water quality and human health risk assessment of nitrate in the SAO watershed (West, Cameroon)

Water is a vital resource for food, agricultural and electrification needs. These needs, combined with population growth and water availability issues, contribute to the high demand for this natural resource, with the corollary of anthropogenic pollution, which degrades its quality. In this context, the present work aims to characterize water quality and assess its suitability for drinking and agricultural purposes using various indices. A total of 25 surface and groundwater samples were collected from the study area. These samples were subsequently analyzed using the HPLC ion chromatography method on a Dionex ICS-1100 to determine chemical parameters, including pH, TDS, Ca2+, Mg2+, Na+, K+, Cl–, SO42−, HCO3–, and NO3–. The pH levels are sometimes acidic and sometimes basic, which is not suitable for human consumption and exceeds the WHO standard. The order of dominant ions is Na+ > Ca2+ > Mg2+ > K+ > NH4+ and NO3− > Cl− > SO42− > F− > HCO3− > PO43−. Water in the research area acquires mineralization through a variety of natural geochemical processes, such as weathering, dissolution, ion exchange processes, and human activity. PCA and various ion ratios reveal that water mineralization is characteristic of anthropogenic impacts and biogeochemical processes. The pollution index indicates that the entire study area is subject to pollution. Nitrate pollution indices reveal that the water sample tests are unsuitable and can cause methemoglobinemia or blue baby syndrome. The water of the study area is suitable for irrigation for almost all types of crops, with a possibility of limited sodium hazards.