137Cs vertical distribution at the deep basins of the North and Central Aegean Sea, Greece

Large volume seawater samples were collected for the determination of Cs-137 concentration along with depth in the deep basins of North and Central Aegean Sea. The vertical Cs-137 distribution showed maximum concentration at the bottom of the basins, while the minimum values corresponded to the intermediate layer, where Levantine water exists. The surface Cs-137 activity is found to lie between the two limits and is originated from the Black Sea waters. The typical oceanographic advection-diffusion balance model is modified to a diffusion-settling-decay balance model to better understand the vertical distribution and variation of the Cs-137 concentration in the deep basins. In addition, the diffusivity of each basin, as well as the settling speed of particulate Cs-137 is also estimated. The results are compared with theoretical approach as well as with previous data. (C) 2014 Elsevier Ltd. All rights reserved.