Fallout from the 1986 Chernobyl nuclear power plant accident has made the Baltic Sea one of the most polluted marine body in the world, with respect to 137 Caesium (Cs). Radioactivity in sediments has generally declined due to decay of 137Cs over the last decades. However, 137Cs contents in subsurface sediments remain at elevated levels compared to the pre-Chernobyl accident. In particular, in the northern Baltic Sea sediments it is considered that Chernobyl fallout created a clear chronostratigraphic marker.
The Radiation and Nuclear Safety Authority (STUK) supervises radiation and nuclear safety in Finland with the purpose of protecting people and the environment from the effects of radiation. STUK measures 137Cs data in the sediments of the Baltic Sea for environmental monitoring purposes.
The Geological Survey of Finland (GTK) contacted STUK and received the data in April 2021. Acting as an EMODnet data ambassador, GTK submitted the standardised data on behalf of the data owner, to the EMODnet Geology portal. The 137Cs peak in the sedimentary record could then potentially be used to define recent sedimentation rates in the area. After this fruitful collaboration, a joint article about 137Cs in the Baltic Sea sediments was published in Sept. 2021 in the Marine Pollution Bulletin, see: Kotilainen et al., 2021, Chernobyl still with us: 137Caesium activity contents in seabed sediments from the Gulf of Bothnia, northern Baltic Sea, https://doi.org/10.1016/j.marpolbul.2021.112924.
