Transport of 137CS, 241AM and Pu isotopes in the Curonian Lagoon and the Baltic Sea

Activities of (CS)-C-137, Am-241 and (PU)-P-239,240 were analyzed with special emphasis on better understanding of radionuclide transport from land via the Neman River estuaries to the Baltic Sea and behavior in the marine environment. Although activity concentrations of Cs-137 in water samples collected the Baltic Sea were almost 100 times higher as compared to the Curonian Lagoon, its activities in the bottom sediments were found to be comparable. Activity (238)pu/Pu-239,Pu-240 and atom Pu-240/Pu-239 ratios indicated a different contribution of the Chernobyl-originated Pu to the suspended particulate matter (SPM) and bottom sediments. The largest amount of the Chernobyl-derived Pu was found in the smallest suspended matter particles of 0.2-1 mu m in size collected in the Klaipeda Strait in 2011-2012. The decrease of characteristic activity (238)pu/Pu-239,Pu-240 and atom Pu-240/Pu-239 ratios towards the global fallout ones in surface soil and the corresponding increase of plutonium (Pu) ratios in the suspended particulate matter and bottom sediments have indicated that the Chernobyl-derived Pu, primarily deposited on the soil surface, was washed out and transported to the Baltic Sea. Behavior of Am-241 was found to be similar to that of Pu isotopes. (C) 2013 Elsevier Ltd. All rights reserved.