Water samples collected from three Rift Valley Lakes (Nakuru, Elementaita and Naivasha) in Kenya in June, 2002 and one lake in southern India (Kolleru) in non-monsoon and monsoon were studied in order to understand the water chemistry of the four tropical lakes. Results indicate that Lakes Nakuru and Elementaita are highly alkaline in nature compared to Lakes Naivasha and Kolleru. Sodium is the major cation while chloride and bicarbonate are the major anions contributing almost in equal proportion (48% each). Both carbonate and silicate weathering contribute to the bicarbonate content in Lake Kolleru; however silicate weathering seems to be the major contributing factor in the bicarbonate content in the Rift Valley lakes. Fluoride content was very high in the rift valley lakes.
The water chemistry of lakes Nakuru and Elementaita strongly reflects the dominance of evaporation and crystallization mechanism. However data points for lakes Naivasha and Kolleru plot to the right of the boomerang envelope - an indication that rock weathering is not the only mechanism controlling the water chemistry of these lakes.
Results obtained indicate that if the waters were in equilibrium with minerals, the waters of lakes Naivasha and Kolleru would be in equilibrium with kaolinite while that of Nakuru and Elementaita would be in the range of albite, quartz and chlorite. The carbonate system suggests that dolomite and aragonite would be the possible minerals in equilibrium in all the lakes.
Mineral solubility, carbonate and silicate weathering, water chemistry