Analysis of the hydrogeological conditions in Bulgaria in connection with the radon potential

Abstract

Natural radon (222Rn) is a radioactive noble gas that occurs in every rock or soil due to the content of radium (226Ra), part of the 238U family, in the lithosphere. Different types of rocks and soils possess different 226Ra content and different permeability. Radon has high mobility and is driven by diffusion and convection with the soil gas throughout connected and water-unsaturated pores and/or cracks in permeable rocks and soils. Therefore, the radon potential of the area could depend on hydrogeology and its particular settings. The study deals with the general characteristics of the groundwater depths in Bulgaria based on the published since 1960’s sources. After analysis of the collected data several distinct regions have been elaborated based on different depth of the groundwater table regarding lithological, tectonic and geomorphological conditions. In addition, zones for screening assessment of groundwater table influence of radon potential have been precised.