engleski

Characterisation of groundwater by stable isotopes and tritium in Croatia

Tracer methods are useful for investigating groundwater travel times and recharge rates, as well as analysis of an impact on groundwater quality. Today the most prevalent tracer methods for analysis and dating of relatively young groundwater are environmental and man-made tracers. The combination of tracer methods and groundwater flow path analysis allows for even better results. The measurements of man-made tracers have not yet come into widespread application in Croatia. The most frequently used tracers were the stable isotopes and tritium. Stable isotopes of oxygen (δ18O) and hydrogen (δ2H) mainly were used as indicators of recharge condition. Tritium (3H) was used for defining relative groundwater age. In one case the stable isotope composition in the karst groundwater and precipitation samples in the western Croatia was analysed and a mean residence time of groundwater was calculated using lumped parameter approach. Protection of groundwater is of fundamental importance due to its use as drinking water, for the industrial needs, irrigation and to its importance for groundwater-dependent ecosystems. Croatia has implemented EU directives (Nitrate Directive, Water Framework Directive and Groundwater Directive) into national legislation. Different protection measures have been introduced to protect groundwater and surface waters. Knowledge about the groundwater age can contribute to better supervision of the effectiveness of protection measures. The first step in analyzing the groundwater age in Croatia was a map creation based on existing data of relative groundwater age. This paper presents the results of the analysis of the data on the composition of stable isotopes and tritium concentrations in groundwater at approximately 100 sites collected during long-term researches. The isotope content shows that researched groundwater is mainly young water. The groundwater originates from recent precipitation. Groundwater older than 50 years is mostly accumulated in semi-confined aquifers of intergranular porosity in northern Croatia and (sub)thermal groundwater.

stable isotopes ; tritium ; groundwater age ; hydrogeology ; Croatia

nije evidentirano