Tracing anthropogenic nuclear activity with 129I in lake sediment

This study reports the first data of 129I fallout in Scandinavia, covering the last 80 years. The investigation is based on sediment sections from a lake in central Sweden. In addition to analysis of 129I, a combination of several radionuclides (210Pb, 137Cs and 14C) was used to establish an accurate chronology of the sediment profile. The concentration of 129I exhibits an increasing trend ( 107 to 109 atoms/g) during the last 40 years, suggesting a significant atmospheric input from the nuclear reprocessing facilities in Sellafield (UK) and La Hague (France). A peak corresponding to fallout from the Chernobyl accident (1986) is clearly distinguishable, whereas the impact of fallout from the nuclear weaponsʹ tests since the early 1950s is not distinguished.