| Sumario: | The study was performed in two areas of Sweden respectively with high natural radioactivity
background (County of Jämtland), and high 137Cs 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 137Cs in Uppsala area and high natural radionuclides activities in Jämtland.
Nevertheless the highest activity value within all the radionuclides was found for 40K in
Skogsvallen, which is part of Uppsala County.
In the comparison between our results and those from previous studies, 232Th and 40K average
activities appeared in the range of other countries, while differences were found for activity of
238U, 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 238U.
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.
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