Radon in the groundwater of Muehlviertel (Upper Austria)

In the occurrence areas of selected crystalline rocks - mainly granites - the Radon-222 content of groundwater has been investigated. The results show a significant correlation with the Uranium concentrations in the rocks. The Uranium concentrations were between 1 and 15 ppm, while the Radon-222 concentrations were between 0.2 and 719.5 Bq/l. To identify Radon-decreasing effects like degasification and admixture of surface water, CO2 partial pressures and Oxygen-18 in water samples were determined and the local hydrological situation has been taken under consideration. Samples which showed clear evidence of Radon-decreasing effects were excluded from further evaluation because they would not represent the full empiric potential of Radon emanation in the aquifer. In combination with geological maps, petrologic information and airborne radiometry, Radon-222 analyses in groundwater can provide important data for Radon potential mapping. The significance of the groundwater Radon analyses can be improved by supplementary hydrochemical and hydrological isotope investigations. (orig.)