title: Origin of radon concentration of Csalóka Spring in the Sopron Mountains (West Hungary).
abstract: We examined the Csalóka Spring, which has the highest radon concentration in the Sopron Mountains (West Hungary) (, yearly average of 227 ± 10 Bq L(-1)). The main rock types here are gneiss and micaschist, formed from metamorphism of former granitic and clastic sedimentary rocks respectively. The aim of the study was to find a likely source of the high radon concentration in water. During two periods (2007-2008 and 2012-2013) water samples were taken from the Csalóka Spring to measure its radon concentration (from 153 ± 9 Bq L(-1) to 291 ± 15 Bq L(-1)). Soil and rock samples were taken within a 10-m radius of the spring from debrish and from a deformed gneiss outcrop 500 m away from the spring. The radium activity concentration of the samples (between 24.3 ± 2.9 Bq kg(-1) and 145 ± 6.0 Bq kg(-1)) was measured by gamma-spectroscopy, and the specific radon exhalation was determined using radon-chamber measurements (between 1.32 ± 0.5 Bq kg(-1) and 37.1 ± 2.2 Bq kg(-1)). Based on these results a model calculation was used to determine the maximum potential radon concentration, which the soil or the rock may provide into the water. We showed that the maximum potential radon concentration of these mylonitic gneissic rocks (cpot = 2020 Bq L(-1)) is about eight times higher than the measured radon concentration in the water. However the maximum potential radon concentration for soils are significantly lower (41.3 Bq L(-1)) Based on measurements of radon exhalation and porosity of rock and soil samples we concluded that the source material can be the gneiss rock around the spring rather than the soil there. We determined the average radon concentration and the time dependence of the radon concentration over these years in the spring water. We obtained a strong negative correlation (-0.94 in period of 2007-2008 and -0.91 in 2012-2013) between precipitation and radon concentration.
authors.affiliation: Department of Atomic Physics, Eötvös Loránd University, Pázmány P. sétány 1/A, H-1117 Budapest, Hungary; Geological and Geophysical Institute of Hungary, H-1145 Budapest, Stefánia út 14, Hungary. Electronic address: freiler.agnes@mfgi.hu.
authors.forename: Ágnes
authors.initials: Á
authors.lastname: Freiler
authors.affiliation: Department of Atomic Physics, Eötvös Loránd University, Pázmány P. sétány 1/A, H-1117 Budapest, Hungary.
authors.forename: Ákos
authors.initials: Á
authors.lastname: Horváth
authors.affiliation: Geological and Geophysical Institute of Hungary, H-1145 Budapest, Stefánia út 14, Hungary.
authors.forename: Kálmán
authors.initials: K
authors.lastname: Török
authors.affiliation: Institute of Diagnostic Imaging and Radiation Oncology, University of Kaposvár, H-7400 Kaposvár, Hungary.
authors.forename: Tamás
authors.initials: T
authors.lastname: Földes
mesh_terms: D060587:Groundwater / Q000737:chemistry*; D006814:Hungary; D011834:Radiation Monitoring; D011886:Radon / Q000032:analysis*; D012588:Scintillation Counting; D012621:Seasons; D012987:Soil / Q000737:chemistry*; D013051:Spectrometry, Gamma; D014875:Water Pollutants, Radioactive / Q000032:analysis*
chemical_list: D012987:Soil; D014875:Water Pollutants, Radioactive; D011886:Radon
keywords: Emanation coefficient; Mylonitic gneiss; Radon in spring water