Assessment of groundwater quality during dry season in Southeastern Brazzaville, Congo.

ABSTRACT

Groundwater samples collected from southeastern Brazzaville, Congo, during July 2008 (dry season) were analyzed for pH, Electrical Conductivity (EC), Total Dissolved Solids (TDS), Calcium (Ca2+), Magnesium (Mg2+), sodium (Na+) , Potassium (K+), Chloride (Cl-), Sulfate (SO4 2-), Bicarbonate (HCO3 -), Fluoride (F-) and Nitrate (NO3 -) using standard procedures (APHA, 1985). The results revealed that all the groundwater samples were below the limits, accordingly to the WHO standards (2004). Except pH of the samples were below the limit (6.5 to 8.5). EC of all the samples were below 300μS/cm. A comparison of the groundwater quality in relation to drinking water quality standards revealed that pH is the disqualifying parameter. The correlation studies and R-mode factor analysis were carried out on the hydrochemical data set. Factor analysis has revealed the factors controlling the hydrochemistry of the groundwater. Four principal factors were extracted by using Kaiser normalization (1) dissolution of magnesium bearing minerals; (2) mineralization; (3) dissolution of calcium-bearing minerals (silicate and carbonate) (4) impact of domestic waste water and septic tank.