14 
Figure 5: 
Annual Co-60 discharges from 
local nuclear facilities into the 
Baltic Sea 1999-2006. 
Figure 6: 
Annual Cs-137 discharges from 
local nuclear facilities into the 
Baltic Sea 1999-2006. 
if r.^,^ ^ 
Bq 
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10 & 
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deposition were 137 Cs and 134 Cs. The total 
input of 137 Cs from Chernobyl to the Baltic 
Sea has been estimated at 4,700 TBq. The 
post-Chernobyl river discharges of 137 Cs were 
estimated in the Marina Balt Study at 300 
TBq, thus comprising 6-7% of the total input. 
The second most important source is global 
fallout from the atmospheric nuclear weapons 
tests carried out during the late 1950s and 
early 1960s. The predominant radionuclides in 
the consequent global fallout were 137 Cs and 
90 Sr, in an activity ratio of about 1.6. During 
the late 1990s the decay-corrected amounts 
of weapons-test 137 Cs and 90 Sr in the Baltic 
Sea have been evaluated at 800 and 500 
TBq, respectively.