Chernobyl & the marine environment : The radiological impact in context

by Pavel Povinec, Scott Fowler, and Murdoch Baxter I he Chernobyl nuclear accident in April 1986 had a significant impact on both the terrestrial and marine environments. The total activity of the nuclear debris released was so high (1-2.10 becquerel) that the radioactive fallout distributed widely after the accident actually dominated anthropogenic environmental levels in various parts of the world. Concentrations of anthropogenic radionuclides generally vary from region to region, according to the location and magnitude of the different sources of contamination. The main global contribution to marine radioactivity, as in the terrestrial environment, is still from fallout from nuclear tests in the atmosphere, particularly during the 1950s and 1960s. However, in some regions, like the Irish and North Seas, the concentrations of anthropogenic radionuclides (e.g. caesium-137 and plutonium239) in the marine environment have been significantly influenced by discharges (e.g. from European reprocessing plants). On the other hand, the Baltic and Black Seas have been the seas most affected by the Chernobyl accident. In all these latter regions the spatial and temporal trends in the concentrations of anthropogenic radionuclides have been quite dynamic. They are a result of changing source terms and marine processes, including horizontal and vertical transport in seawater, marine sedimentation, resuspension from sediment and biological uptake, and food-chain transfer.