Using 137Cs measurements to detect changes in sedimentation rates in a floodplain area of northern Norway. Preliminary results of a field sampling campaign

Floodplain sediment records may provide important information on soil erosion and deposition rates over large catchments and for different time windows. In this context, the use of anthropogenic and geogenic radiotracers has recently attracted increasing attention for their ability to act as sediment markers and to reflect the environmental impacts due to variation in land use and recent climate changes. ¹³⁷Cs is one of the most employed radiotracers for sediment chronology due to its easy detectability in the environment and to its strong ability to be retained by sediments in depositional areas. ¹³⁷Cs activity in sediments reflects the temporal fallout occurred in the area and, as such, it proved to be a very effective indicator to reconstruct the trend of soil erosion and sedimentation rates during the last 6-7 decades. In this contribution, a floodplain area in northern Norway was identified as a ‘pilot site’ to explore possible anthropogenic impacts and climate change effects on deposition rates from uncultivated sites. Sediment cores collected in the area were analysed for ¹³⁷Cs content and provided evidence of Chernobyl fallout. This result made it possible to obtain information on sedimentation rates for different time windows (i.e. 1963-1986 and 1986-2024) and suggested an increase of sedimentation rates during the last 4 decades.