PLUTONIUM IN THE BALTIC-SEA

For assessment of plutonium in the Baltic Sea, plutonium has been studied in precipitation, water, sediments and macroalgae (Fucus sp.). Data collected over 25 years are available. The major source of plutonium in the Baltic Sea is fallout from nuclear tests. The Chernobyl accident contributed very little to the overall activity concentrations of Pu-239+240 but the contribution of Pu-238 and Pu-241 was more significant. In certain parts and adjacent areas of the Baltic Sea, European reprocessing facilities have given a significant contribution of all plutonium isotopes. In the Baltic Sea the major fraction of plutonium is rapidly associated with sediments and only 1% is present in the water column. Scavenging processes other than association with Fe/Mn oxyhydroxides are most important. The long-term residence compartment indicate a residence time of 8-10 years.