Iodine-129, Iodine-127 and Cesium-137 in seawater from the North Sea and the Baltic Sea

In 2009, the activity concentration of 137Cs was at least 6 times higher in the Baltic Sea (37 Bq m−3) than in the North Sea (5.9 Bq m−3), due to release of 137Cs from sediments in the Baltic Sea, which were contaminated by the Chernobyl accident and - to a minor degree - the atmospheric explosions of atomic bombs. The results are discussed by comparing the results of our previous work and the current study demonstrating the continuing disequilibrium of 129I/127I atomic ratio in the environmental compartments.