| Summary: | The primary source of 137Cs in Norway is the Chernobyl accident, and several decades after the accident, there is still a substantial amount in the environment. The area of Hattfjelldal, within the catchment area of the river Vefsna, is situated in the southern parts of the county Nordland, which was especially affected. In the present work, soil samples were taken from two different sites, Nerlifjellet and Groalia in the area of Hattfjelldal, based on knowledge about the relatively high activity of 137Cs in this area and the differences in soil composition. The samples from the two soil types were analysed to investigate any differences in distribution of 137Cs, binding and mobility of 137Cs as well as stable 133Cs, and if any differences could be connected to differences in soil components. The soil was collected using a soil corer and divided based on the top 3 cm and visible layers. For Groalia, the 0-3 cm layer was further divided based on a visible mineral layer (2-3 cm) and an organic layer (0-2cm). The soil layers from Nerlifjellet were characterized with 13- 97% organic material, compared to Groalia with 5-40%. The pH was similar dissimilar. A grain size analysis for the layers with an organic matter content of < 20% show that the mineral soil in Nerlifjellet consist of mainly sand (73%) while the mineral soil from Groalia mainly consisted of silt (39-57%). The activity concentration of 137Cs was identified to be 200-900 Bq/kg dry soil from Nerlifjellet, depending on the soil layer, while for the soil from Groalia it was 36-1300 Bq/kg. The activity density per cm of 137Cs in the soil from Nerlifjellet was identified to be 1.0-1.1 Bq/m2 per cm, depending on the soil layer. For the soil from Groalia, the activity density of 137Cs per cm was 0.19-6 Bq/m2 per cm. For the soil from Nerlifjellet, 137Cs were more evenly distributed through the soil core than for the soil from Groalia, where 137Cs were mainly found in the upper 3 cm of the soil core (86%). Based on this, 137Cs seem to be more mobile in the ...
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