Hydrochemical and isotopic studies to understand quality problems in groundwater of the Niğde Province, Central Turkey
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This study seeks to decipher the hydrochemistry, recharge sources, and the possible factors controlling the chemistry of groundwater in Niğde Province of central Turkey. This was done by conducting hydrochemical, multivariate statistical, and stable isotope analysis on 37 well and spring water samples collected in the wet and dry seasons of 2016. The major ion abundance in the groundwater is in the order Ca2+ > Na+ > Mg2+ > K+ and HCO3- > SO42- > Cl-. This accounted for the dominance of Ca–SO4–HCO3 water type with other mixed water types, reflecting the geology of the area, which is predominated by carbonate lithologies. All the physico-chemical parameters generally comply with the WHO and Turkish national guideline values for drinking water except TDS, Ca2+, SO42-, NO3-, and As. The elevated amounts of TDS, SO42-, and NO3- were largely from anthropogenic sources. The studied well and spring water samples are suitable for irrigation purposes in terms of their sodium hazard, but with regard to salinity hazard, the well water samples are not suitable for irrigation purposes due to their high salinity values. Three factors that explain 85.2% of the total variance of the data point to water–rock interaction and mixing with thermal waters as the principal factors controlling the chemistry of the groundwater. Metal pollution load was significantly higher in the wet season than in the dry season with arsenic as the key contaminant (0.69–391.14 µg/L and 0.29–43.6 µg/L in the wet and dry seasons, respectively). The tritium concentrations reveal that the well waters have longer residence time and water–rock interaction than the spring waters and are thus recharged from older groundwater sources. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.