engleski

Usage of Tritium, δ D, δ 18O and Chemical Data in the Hydrogeological Investigation of the Karstic Area - Lička Jasenica

Traditional investigations of groundwater resources in karstic areas usually utilize geological, hydrogeological and water quality data in order to establish a conceptual model for the investigated aquifer. Sometimes, such data are not always fully available. In order to overcome these obstacles the combined hydrogeological and geochemical approach was used for a conceptual model of the investigated karstic aquifer. In August and November 2007 and April 2008, water samples were collected from two springs: Veliko vrelo and Malo vrelo. Prior to taking groundwater samples, EC, TDS, T and pH were measured. Water samples were analyzed by LabAlliance ion chromatographer (concentrations of major anions) and Perkin Elmer AAS (concentrations of major cations) at the Croatian Geological Survey. The &#948; 18O and &#948; D were analyzed by using the CO2 equilibration and the zinc reduction method at the Joanneum Institute, Graz. Tritium activity in water samples was measured at the Ruđer Bošković Institute by a gas proportional counting (GPC) technique. From water sample (50 ml), CH4 is obtained by reaction of water with aluminium carbide at 150°C. Purified CH4 is then used as a counting gas in a multi-wire GPC. The lowest tritium activity that can be distinguished from the background, i.e., the limit of detection is 1.9 TU. According to the chemical composition the spring waters belong to the Ca-HCO3 hydrochemical type. Total dissolved solids, EC, T and &#948; 18O and &#948; D show that on both springs have the same catchments area. The lowest value of 3H was measured on Veliko vrelo in 08-2007 (<2.4 T.U.) during hydrological minimum and on Malo vrelo in 11-2007 (<2.4 T.U.) during hydrological medium. The highest values of 3H were measured on both springs during hydrological maximum. The tritium indicated that the delay response of the Malo vrelo comparing to the Veliko vrelo.

hydrogeology; hydrogeochemistry; karstic aquifer; isotopes

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