THE DISPERSION OF CS-137 IN THE AEGEAN SEA

The radiological regime of the Aegean Sea until 1986 was characterized by the impact of world wide fallout. The levels of Cs-137 measured in the Aegean Sea, during 1984-1985 varied within 2.58+/-0.27 Bq m(-3). Since 1986, the impact of the radioactive contamination from the Chern obyl nuclear accident resulted in an increase of Cs-137 levels in sea water of up to one order of magnitude. The Chernobyl ''total caesium'' deposition (Cs-137 + Cs-134) in the Aegean Sea has been estimated to be approximately 800 TBq (2/3 of which was Cs-137). Besides that, the North Aegean Sea is exposed to the influence of the Black Sea discharg es to the Sea of Marmaras through the straits of Dardanelles. As it ha s been shown elsewhere, the predicted total Cs-137 outflow from the Bl ack Sea into the Sea of Marmaras is 247 TBq. In the present study, the preliminary results of determinations of Cs-137 concentrations in sur face sea water in selected regions in the Aegean Sea, during 1993, are evaluated with consideration of the sources of pollution. Taking into account the horizontal circulation of water mass from the Marmaras Se a to the Aegean Sea an effort is made to assess the impact of Cs-137 d ischarging to the Aegean Sea as a result of purification processes in the Black Sea through the Marmaras Sea and Dardanelles straits.