Studies of the transfer of radionuclides and dose rate assessments in the pasture lands located in the counties of Uppsala and Jämtland

Abstract: The study was conducted in the pastoral lands of two Counties, Uppsala and Jämtland Counties. Soil and grass samples were collected from six study areas. Two from Uppsala County: Lövstalöt and Möjsjövik, and four from Jämtland County: Backfors, Hallen, Myrviken and Vikdrolet. Milk samples were also collected from Lövstalöt (Uppsala County) and Hallen and Oviken (Jämtland County). The study aims at analyzing the presence and activity concentration of natural radionuclides and 137Cs from Chernobyl accident and determines their transfer factor from soil to grass and from grass to milk. It also describes the migration of 137Cs and the homogeneity of concerned natural radionuclides in the soil profile of the study areas. The third objective of the study was to assess in situ and laboratory outdoor dose rate in air of radionuclides in the study areas and make comparison between Counties and the methods. Higher concentrations of natural radionuclides were found in Jämtland study areas than in Uppsala due to the geological background of the area rich in natural radionuclides. But, higher concentration of 137Cs was found in Uppsala than in Jämtland due to higher anthropogenic deposition from Chernobyl accident. Activity concentrations of the radionuclides were higher than suggested by UNSCEAR. In Uppsala study areas, higher total annual effective dose rate of radionuclides were found in the laboratory measurement than in situ. A similar finding was obtained in Jämtland study areas except in Hallen. In Jämtland County, the contribution of artificial radionuclide (137Cs) was not very significant to the total annual effective dose rate and much concern could be given to the natural radionuclides dose rate assessment. In Uppsala County, however, it can be advocated that equal concerns should be given to both artificial radionuclide (137Cs) and natural radionuclide for dose rate assessment due to their significant contribution to the total annual effective dose rate estimated in the study.