Speaker
Description
The geological structure of the Western Carpathians in Slovakia is very diverse and reflected in natural radioactivity. Slovakia is relatively rich in mineral, as well as deposit-forming occurrences of uranium and thorium ores. Likewise, many rock formations contain potassium in their basic matrix. The origin of the increased surface radioactivity may lie either in the lithogeochemical composition of the near-surface horizon with an increased content of potassium, uranium, radium, thorium and radon or in the tectonic structure, which allows the free escape of radon gas to the earth's surface thanks to faults. Two locations in Slovakia with potentially dangerous levels of natural radioactivity are described in the article. At the Kravany site in the Kozie Chrbty Mts, there are surface occurrences of uranium as a residue after insufficient environmental cleanup after uranium mining was completed. The average values of the absorbed dose rate (136.4 nGy.h-1) and the uranium concentration (8.8 ppm eU) greatly exceeded the average values for the rocks of the Western Carpathians, 63.3 nGy.h-1 and 3.3 ppm eU, respectively. The maximum measured values of 1482.6 nGy.h-1 and 223.9 ppm eU were on the order of 10- to 100-times higher than the average values. The second location is a protected natural formation – a travertine mound with an active geyser – Sivá brada near Spiš Castle. In this case, it is the yield of radioactive elements by carbonate solutions at the intersection of faults, and the cause of increased natural radioactivity is the high uranium content in solutions with a maximum of up to 43.6 ppm eU. The maximum absorbed dose rate reaches 198.2 nGy h-1. Such values at the studied locations may represent a significant health risk for residents staying here throughout the year, and this information should be considered when planning future human activities in these areas.