Ms Lenka Hrušková (Charles University in Prague)Dr Viktor Goliáš (Charles University in Prague)
Goliáš V.1, Hrušková L.1, Lipanský T.1, Przylibski T.A.2, Procházka R.3 1Charles University in Prague, Faculty of Science, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org 2Wrocław University of Technology, Faculty of Geoengineering, Mining and Geology, email@example.com 3Lesní 1079, Dobřichovice, Czech Republic, firstname.lastname@example.org Keywords: groundwater, mineral water, springs, gamma dose rate, radon progeny Radioactive mineral waters (rich in dissolved 222Rn) are highly valued for their medical use. Therefore they have been intensively explored in last years (2005–2014) in Orlica-Sněžník dome and Krkonoše-Jizera crystalline areas. Springs of radioactive medicinal water are bound up with the Cambrian/Ordovician orthogneisses (the Krkonoše, Kowary and Jizera orthogneiss). For these purposes an exploration method has been developed as a combination of GIS (ArcMap 9.1–10.1) for the area preparation followed by field radiohydrogeochemical mapping. As basic GIS layers a geological map 1:50000, topography, airborne gamma spectrometry, linear structures from Remote Sensing were used. The field radiohydrogeochemical mapping was realized in scale 1:10000 in perspective areas selected by GIS preparation. All water manifestations (wetlands, springs, man-made objects) were measured by gamma as an indicative method. In case of positive results (increased gamma in water) the water was sampled and a passportized field record was written. The exploratory groups were equipped with sensitive field scintillometers RP-11 with RFS-05 gamma probes. The 222Rn activity in water samples was determined by the emanometric method (RP-25) at the field base. Control analysis in the laboratory by LSC (QUANTULUS) was made. Standardization of all methods is commonplace. More than 50 water sources with activity above 1500 Bq/L (i.e. "radioactive mineral waters") were found in the whole territory. The highest radon activity reaches 6215 Bq/L in case of the Michael spring near Nové Město p. Smrkem. Waters are cold (5–9.5 °C) and low-mineralized (TDS < 100 mg/L), 222Rn is the only important component. Gamma activity of fresh flow water is close to zero; it is free of the short-lived 222Rn gamma active progeny (214Pb and 214Bi). Field measuring of fresh water gamma activity growth indicates its effective age about 7 minutes only. But the gamma activity is really detectable in frequent cases where there is a slowdown in the flow and mud or sediment of organic material is created. In fact, we have a lot of evidence from the field Gamma dose rate in water reaches 4624 nGy/h. Relationship of gamma (gamma dose rate in water) and radon-in-water activity is complicated; both quantities correlate freely. It depends on the specific situation of every single spring. Generally we can say that the gamma dose rate is a function of radon-in-water activity, water velocity and flowing water volume: Dw = f(Av, v, V). Gamma method, in spite of radioactive disequilibrium, is useful for exploration of radon-rich waters in crystalline terrains on the basis of our empirical findings in the field, much better than the "blind" method.
Dr Viktor Goliáš (Charles University in Prague)
Ms Lenka Hrušková (Charles University in Prague) Dr Radek Procházka (Lesní 1079, Dobřichovice) Prof. Tadeusz Przylibski (Wrocław University of Technology) Mr Tomáš Lipanský (Charles University in Prague)