Contamination of the southern Baltic Sea with 137Cs and 90Sr over the period 2000–2004

Changes of the 137Cs activity concentrations in the southern Baltic Sea waters were investigated over the period 2000–2004 and distribution of the 90Sr concentrations was determined in 2004. In the discriminated period further decrease of 137Cs concentrations was observed. The average activity concentration of 137Cs declined from 59.4 Bq/m3 in 2000 to 45.1 Bq/m3 in 2004. The greatest changes of 137Cs activities occurred in 2003 as a consequence of the medium-size inflow of a saline waters from the North Sea. This inflow affected 137Cs activities as well as its distribution in the Baltic Sea. Changes in 90Sr activity concentrations proceeded at much slower rate. The average activity concentration of 90Sr was equal to 8.7 Bq/m3 in 2004. The annual fluvial 137Cs fluxes from the Vistula river were also estimated. In 2000, the 137Cs load from Vistula was of an order of 0.15 TBq/year, and in 2004 0.05 TBq/year.