Activity concentration and transfer factors of natural and artificial radionuclides in the Swedish counties of Uppsala and Jämtland

The study was performed in two areas of Sweden respectively with high natural radioactivity background (County of Jämtland), and high Cs deposition area deriving from Chernobyl fallout (County of Uppsala). Aims of the study were the calculation of activity concentration and transfer factors for all 6 radionuclides in the two areas and analysis of influence of soil characteristics on radionuclides behavior. In both the locations 25 centimeters depth soil cores were collected together with grass samples. After analysis with HPGe detector results showed as expected high levels of deposition of Cs in Uppsala area and high natural radionuclides activities in Jämtland. Nevertheless the highest activity value within all the radionuclides was found for K in Skogsvallen, which is part of Uppsala County. In the comparison between our results and those from previous studies, Th and K average activities appeared in the range of other countries, while differences were found for activity of U, which appeared markedly higher if compared to literature. Transfer factors found in our study for all the natural radionuclides were generally higher in respect to literature, whereas the opposite values resulted from cesium TF values. Comparison between the main natural radionuclides suggested that natural radioactivity background seems to be mainly due to U. From our results available phosphorus content in the soil seemed to have the lowest influence on the behavior of all the radionuclides, compared with other soil parameters. Furthermore Möjsjövik, one of Uppsala sampling sites, showed a different behavior from all the other sampling sites, probably due to differences in soil characteristics.