Caesium-137 in the Eastern Mediterranean - impact sources and marine pathways

The dispersion of super(137)Cs is evaluated in the wide area of the Eastern Mediterranean (Aegean Sea, Cyprus Sea, Levantine Sea, Ionian Sea, Adriatic Sea) and in the Black Sea adjacent to the Northeastern Mediterranean with respect to the impact sources. Additionally, the time evolution of super(137)Cs is evaluated in the Aegean and Cyprus Sea with regard to the possible future installation of a nuclear power plant in Akuyu at the Turkish coast of the Southeastern Mediterranean. The impact source of radioactive pollution in the Northeastern Mediterranean has been defined as the mouth of Dardanelles in the North Aegean Sea. As the Aegean Sea is adjacent by its north part to the Black Sea through the Straits of Dardanelles, the Black Sea water mass enters the Aegean Sea via surface current circulation during the water exchange procedure between the two basins. The super(137)Cs levels detected till April 1986 were due to worldwide fallout and varied between 2.3-2.9 Bq m" super(3) from the southern to the northern part of the Aegean Sea. The respective values of the Cyprus Sea, the Libyan Sea and the Levanten Basin were lower. Considering the generic inventory of super(137)Cs in the Black Sea - Aegean Sea during 1993, the average concentration of super(137)Cs in sea water in the Black Sea varied up to 130 Bq m" super(3). The respective value in the mouth of Dardanelles was 120 plus or minus 8 Bq m" super(3), whereas the estimated mean value for the Aegean Sea was 20.7 plus or minus 14.7 Bq m" super(3) (maximum of 9.3 plus or minus . 4.2 Bq m' super(3) has been excluded). This value was quite high, compared to the pre-accident levels 2.6 plus or minus 0.3 Bq m" super(3) or to the respective value for the Ionian Sea 9.2 plus or minus 2.5 Bq m" super(3). The observed values in the Cyprus Sea, the Libyan Sea and the Levanten Basin were significantly lower. Considering the radioactive pollution of the Black Sea from the Chernobyl deposition, the mouth of Dardanelles has been the impact source of the soluble artificial radionuclides, which remain in the water column for a reasonable time and and are transported and distributed by the water mass exchanging. Thus, we assume that a more or less predictable amount of super(137)Cs is discharged to the Aegean Sea, Eastern Mediterranean, during the purification processes of the Black Sea through the Dardanelles channel and dispersed to the South-Western Aegean Sea via surface current circulation with respect to the sinkin