Investigation of the effects of agricultural and mining activities on surface water and groundwater quality in the vicinity of Kesikkopru dam (Ankara and Kırsehir)

In this study, hydrogeochemical and isotopic analyses of surface water and groundwater resources located around Kesikköprü Dam were carried out. The primary aim of this study is to determine the effects of agricultural and mining activities on water resources in the study area. For that purpose, the geological, hydrological and hydrogeological structure of the region have been investigated, and the necessary findings have been presented to reveal the hydrogeochemical characteristics of the water resources in the area. Hereby, samples were taken during the wet and dry periods from 21 sample points, which were identified after the preliminary field studies. The physico-chemical parameters (electrical conductivity, pH, temperature, oxidation-reduction potential and dissolved oxygen contents) of the water samples were determined in situ, and major ion and trace element analyses and stable isotope content determinations were carried out in accredited laboratories. The results obtained were analyzed by using PhreeqC and ArcMap programs and those results were converted into necessary data and maps. The results of analysis were interpreted with the help of different diagrams. According to the results of the major ion analysis, the chemistry of the waters was shaped by the water-rock interaction, in some samples the chemical evolution took place as a result of the dissolution of the evaporites, while the existing chemical form in some other samples was acquired as a result of salinization by cation exchange. The samples are generally saturated with dolomite, calcite and aragonite minerals. According to the stable isotope contents of the waters, some samples (especially mine pit lakes and Kesikköprü Dam Lake) deviate from the Ankara Meteoric Water Line and are under the effect of evaporation. The slope of the evaporation line is compatible with the relative humidity in the region. At some sampling points, sodium, sulfate, nitrate and arsenic are above the limit values given by the World Health Organization and Turkish Regulations on Water Intended for Human Consumption. It has been determined that the use of some of the samples for drinking water purposes is undesirable. Studies have shown that the pollution in the region is mainly of agricultural and geogenic origin.