Hydrogeochemical and isotopic characterization of groundwater at Žitný Island (SW Slovakia) Z. Ženišová, P. P. Povinec, A. Šivo, R. Breier, M. Richtáriková, A. D ˇ uric ̌ ková and A. L’uptáková ABSTRACT Hydrogeochemical investigations and spatial variations studies on the distribution of water isotopes and radiocarbon in the groundwater of Žitný Island (Rye Island) were carried out. Žitný Island represents the largest groundwater reservoir in Central Europe (about 10 Gm 3 ). The chemical composition of the groundwater of Žitný Island depends mainly on the chemical composition of Danube water, as well as on the length of its infiltration from the Danube River. The groundwater is characterized by potamogenic mineralization, and its chemical composition is influenced by anthropogenic contamination. Sub-surface water profiles showed enriched δ 18 O levels up to around 20 m water depth, and depleted values for deeper waters. The observed isotopic composition of the groundwater is similar to Danube water, suggesting that the Danube River is the main source of the Žitný Island groundwater. The core of the sub-surface 14 C profile represents contemporary groundwater with 14 C values above 80 pMC. Z. Ženišová A. D ˇ urič ková Department of Hydrogeology, Faculty of Natural Sciences, Comenius University, 842 15 Bratislava, Slovakia P. P. Povinec (corresponding author) A. Šivo R. Breier M. Richtáriková Department of Nuclear Physics and Biophysics, Faculty of Mathematics, Physics and Informatics, Comenius University, 842 15 Bratislava, Slovakia E-mail: povinec@fmph.uniba.sk A. L’uptáková Slovak Hydrometeorological Institute, 833 15 Bratislava, Slovakia Key words | carbon-13, carbon-14, groundwater, oxygen-18, Slovakia, Žitný Island INTRODUCTION Hydrogeochemical and isotope studies of groundwater have been carried out in the past with the aim to better under- stand its origin, formation, dynamics, climatic impacts, its vulnerability and protection against anthropogenic impacts in the world (Gonfiantini et al. ; Kendall & McDonnell ; Aggarwal et al. a, b), and specifically in Central Europe (Rank et al. ; Deák ; Povinec et al. ; Schiavo et al. ). Recently, new geostatistical tools have been developed to integrate isotope data into a relational database covering also hydrogeology and hydrochemistry of groundwater. Using geographical information system, it has been possible to create temporal-spatial isotope maps of groundwater (Bowen et al. ; Aggarwal & Araguás- Araguás ). Isotope data together with hydrographic data have been used for better characterization of specific groundwater regions, for studying groundwater ages, infiltration areas, recharging characteristics of groundwater reservoirs, impact of climatic changes and a danger of groundwater contamination (Vitvar et al. ; Ockenden et al. ; Szczucinska ; de la Torre et al. ). These have been important studies for the protection and sustainable exploi- tation of groundwater from the long-term perspective. Although several isotope hydrology studies were carried out in Central Europe (Rank et al. , , ; Deák ; Vitvar et al. ; Miljevic ´ et al. ), including Slova- kia (Malík et al. ; Michalko ; Franko et al. , ; Povinec et al. ), information on temporal and spatial groundwater variations, and specifically isotope depth profiles, have been missing. Development of an iso- tope groundwater database for Central Europe is underway which will identify regions with limited data sets, where new sampling campaigns and isotope analysis will be carried out. It is believed that with recently 929 © IWA Publishing 2015 Hydrology Research | 46.6 | 2015 doi: 10.2166/nh.2015.187 Downloaded from http://iwaponline.com/hr/article-pdf/46/6/929/370618/nh0460929.pdf by guest on 09 November 2023