Radon exhalation rate and emanation factor values in relation to different soil characteristics.

The natural background radiation to humans comes both from outside the Earth (cosmic radiation) and from radioactive isotopes found on Earth (terrestrial radiation). Radionuclides of terrestrial origin are partly external exposure and partly internal exposure via ingestion and inhalation. One of the most important sources of external terrestrial radiation is soil, where the most significant isotopes found are uranium-238, uranium-235 and thorium-232, members of the decay series, and potassium-40. The soil can be classified into different types and therefore have a wide range of physical and chemical properties. These properties can influence the movement and possible accumulation of radionuclides in different soil layers. In this study, soil samples were collected from the Transdanubia region (Hungary), based on the grid network used by the JRC (European Commission's Joint Research Centre). The soil samples were analysed by gamma spectrometry to determine the Ra-226 activity concentration. The massic radon exhalation rate of the soils and the emanation factor were also determined. The aim of the study is to investigate the possible effects of the soil type on the Ra-226 activity concentration, massic radon exhalation rate and emanation factor. The average of Ra-226 activity concentration, massic radon exhalation rate and emanation factor were 29.3 Bq/kg, 29.04 mBq/kgh and 0.25, respectively. These values are similar to world averages and the results of other studies; no extreme values were found. There was observed a weak correlation between the Ra-226 activity concentration and the massic radon exhalation rate, but it was did not find any correlation between the Ra-226 concentration and emanation factor.