Abstract: The hydrochemistry of groundwater from aquifer AQ-2 exploited by the National Company of Water supply (NCWD) located at Pointe-Noire, south-west of Congo-Brazzaville was evaluated for drinking water. Eleven piezometers were sampled. The physical parameters (pH), Electric Conductivity (EC), Total Dissolved Solids (TDS) as well as the concentrations in major ions Ca2+, Mg2+, Na+, K+, Cl -, SO42-, HCO-3 are within the WHO prescribed limits for drinking water. Two chemical facies are predominant mixed cations HCO3 (36.36%) and Ca-Mg-HCO3 (27.27%). Water-rock interaction characterized by the dissolution of carbonates and silicates plays a primordial role in the chemical composition of the groundwater. The Na/K ratio makes it possible to classify the piezometers in three groups which were also revealed by hierarchical cluster analysis. The hydrochemical study of the aquifer AQ-2 showed that the major cations and anions, the pH, electric conductivity, the total dissolved solids, total alkalinity and the total hardness which characterize the chemical composition of the tablecloth are within the limits allowed for the drinking water according to standards WHO.
C. Tathy, L. Matini, B. Mabiala, F. Antoine and G. Moukandi Nkaya, 2010. Hydrochemistry of Groundwater in the Aquifer AQ-2 in Pointe-Noire, South-West Congo-Brazzaville. Research Journal of Applied Sciences, 5: 361-369.