SELF-PURIFICATION PROCESS OF THE BALTIC SEA FROM 137 Cs RADIONUCLIDE in 1986-2006

Analysis of self-purification process from 137 Cs in the Baltic Sea after Chernobyl Power Plant (ChPP) accident is carried out. The beginning of this process took place in 1989-1990 when its concentration became homogenous in the surface waters. The self-purification occurred irregular, having some leap of 137 Cs concentration in 1995, 1999, 2002, 2004 when experimental results exceeded theoretical one. Last time the annualy average 137 Cs concentration was (42±4) Bq/m 3 in 2006. This result is in the good agreement with