Investigation of Hydrogeochemical Characteristics and Quality of the Water Resources in Şiran (Gümüşhane) District Center, Turkey

The study area is located of Şiran District Center in the southwest of Gümüşhane (NE Turkey). In this study, hydrogeochemical characteristics of water resources in district center were examined and metal element contents were determined. In the study area, the basement rocks are represented by Eocene Kelkit formation, which is composed of sandstone, claystone, marl, shale and tuff, and this unit is covered unconformably by the Quaternary aged alluvium. These units form granular porous unconfined aquifers according to the hydrogeological features. The pH, specific conductance (SC) and hardness (Fr°) values of the water resources in the study area varied between 5.41-7.48, 106.9-141.3 µS/cm and 4.72-6.78 (n= 18), respectively. According to the classification of Intra-Continental Water Resources, these data show that the samples are mostly class-I and II, rarely class-III water quality characteristics. The water resources in the study area are generally classified as Ca-Mg-HCO3 type carbonated (Ca+Mg>Na+K), and generally their weak acids are more than strong acids (HCO3>SO4+Cl). In the study area, (Ca+Mg)/(SO4+HCO3) ratios indicated the effect of silicate weathering in the waters, and the Cl/(Cl+HCO3) and (Na+K)/(Na+K+Ca) ratios show that the chemistry of waters is controlled by the chemical weathering of rock-forming minerals, hence, reflect the water-rock interaction. Except for a few, the concentration of dissolved potentially toxic elements in the water samples were distributed within acceptable limits. Consequently, the hydrogeochemical results showed that the water resources in the study area were in the category of good class waters in terms of drinking water.