137Cs activity distribution in the Lithuanian coastal waters of the Baltic Sea

The main Cs-137 accumulation zone in the study area was found to be located at depths below the 50-metre isobath, i.e. below the layer of hydrodynamic activity. In coastal waters not influenced by the fresh water discharge from the Curonian Lagoon, (CS)-C-137 occurs mostly in soluble form. The particulate Cs-137 activity concentration in the marine area affected by Curonian Lagoon water can make up 10% of the total Cs-137 activity concentration. The circulation model was developed to assess the distribution of artificial radionuclides in Lithuanian territorial waters. The model was validated on the basis of data acquired during the measurement campaign in the Lithuanian part of the Baltic Sea and the Curonian Lagoon in the years 1999-2001. The model enables the Cs-137 activity concentration to be simulated as a passive admixture (error within c. 15%).