Discharge of 137Cs and 90Sr by Finnish rivers to the Baltic Sea in 1986-1996

The total amounts of Cs-137 and Sr-90 transported from Finland by rivers into the Gulf of Finland, Gulf of Bothnia and Archipelago Sea since 1986 were estimated. The estimates were based on long-term monitoring of Cs-137 and Sr-90 ill river and other surface waters and on the statistics of water discharges from Finnish rivers to the above sub-areas of the Baltic Sea. The total amounts of Cs-137 and Sr-90 removed from Finland into the Baltic Sea during 1986-1996 were estimated to be 65 and 10 TBq, respectively. The results show that, although the deposition of Cs-137 was much higher than that of Sr-90 after the Chernobyl accident, the amount of Cs-137 removed from Finland is only six times as high as that of Sr-90. This emphasizes the importance of Sr-90 while considering radiation doses from surface waters and Cs-137 while estimating doses via pathways from catchment soil, lake sediments and biota after a fallout situation. (C) 2001 Elsevier Science Ltd. All rights reserved.