THERMODYNAMIC MODELLING OF THE EQUILIBRIA IN LAKE BARINGO, KENYA

Abstract

The  equilibria  that  control  the  composition  of  a  lake  is  presented  using  lake Baringo,  Kenya,  as  an  example.  Lake  Baringo  (037’N,  3605’E)  lies  very  close  to the equator in the Baringo basin in the Eastern Rift Valley, Kenya. Water from the lake  was  analysed  chemically  using  standard  analytical  techniques  to  obtain  the stoichiometric concentrations of the major anions and cations. However, this does not  indicate  how  the  components  are  distributed  amongst  possible  species.  The speciation calculation was performed using the available equililbrium constants for all  the  metal  –  ligand  and  proton  –  ligand  species  identified.  At  pH  8  the composition of the water of lake Baringo was Ca2+(58.88%); CaCO3  (41.12%); Mg2+(97.33%); MgCO3(2.88%); HCO3-(98.27%) and SO42-(99.88%). Sulphate forms very weak  complexes  of  calcium  and  magnesium  and  was  excluded  from  the  model. MgHCO3+, CaHCO3+and MgSO4 were found to be minor species.