HYDROGEOCHEMICAL MODELING OF WATERS IN MOGAN AND EYMIR LAKES SPECIAL ENVIRONMENTAL-PROTECTION AREA, ANKARA, TURKEY

On the basis of water-rock interactions, hydrogeochemical characterist ics of spring, stream, wetland, and lake waters in the Mogan and Eymir Lakes special environmental protection area of Turkey were modeled us ing a reaction-path simulation method. Geochemical characteristics of surface waters, mineralogical sources of ion concentrations in the spr ings, mixing, and evaporation/dilution relationships between the compo sitions of input flows and the lakes and between the compositions of i nflows and wetlands were quantitatively determined. Major ion distribu tions in spring water reflect mineralogical characteristics of the lit hologies that have been traversed by related springs before reaching t he surface. Mixing and evaporation/dilution calculations show that app roximately 41 to 83% of the ion concentrations in the Mogan Lake is pr ovided by groundwater and the remaining is supplied by streams. In add ition to the mixing, cation exchange and carbon dioxide (CO2) outgasin g reactions are also required to obtain the observed lake composition. Chemistry of the wetland waters provided by Mogan Lake by way of grou ndwater and the regulator canal is primarily controlled by CO2 ingasin g and exchange reactions. Small amounts of dilution by other sources a re also required. The majority of ion concentrations in Eymir Lake wat er, on the other hand, is supplied by the wetland area. Ion concentrat ion contributions of groundwater from other areas to the Eymir Lake ar e calculated to be approximately 8 to 59% of the total input. Silica p recipitation, exchange, and evaporation are the effective processes in the production of Eymir Lake water concentrations. In general, the ra nges of model results are consistent with those of hydrological data.