International Science Community Association Research Journal of Chemical Sciences 2231 - 606X 2 1 2012 January 18 Seasonal Groundwater Quality Variation in Brazzaville, Congo 7 14 EN Matini L. 1 Department of Exact Sciences, E.N.S, University Marien Ngouabi, B.P 69 Brazzaville, CONGO Tathy C. 2 Moutou J.M. 3 > Research Paper 2011 8 29 2012 January 18 Groundwater samples collected from southwestern Brazzaville, Congo, in rainy and dry seasons of the year 2008 were analyzed for pH, electrical conductivity, total dissolved solids, calcium, magnesium, sodium, potassium, chloride, sulfate, bicarbonate, fluoride, and nitrate to assess the seasonal variation of groundwater quality. The Results of the chemical analysis indicate that groundwater was characterized by Mg-Ca-HCO facies in rainy season and Na-HCO facies in dry season. In rainy season, silicate weathering was a dominant process, controlling the groundwater chemistry, followed by carbonate weathering and ion exchange; while in dry season silicate weathering was also the prime process over the governing of the groundwater quality followed by ion exchange and carbonate weathering. Leaching is the main contributor in rainy season. Copyright@ International Science Community Association