DISTRIBUTION OF LOW-LEVEL NATURAL RADIOACTIVITY IN A POPULATED MARINE REGION OF THE EASTERN MEDITERRANEAN SEA

The levels of natural radioactivity have been evaluated in the water column of an eastern Mediterranean region (Saronikos Gulf), with respect to the relevant environmental parameters. A novel methodology was used for the determination of natural radionuclides, which substitutes the time-consuming radiochemical analysis, based on an in situ sample preconcentration using ion-selective manganese fibres placed on pumping systems. With regard to the results obtained, 238U-series radionuclides were found at the same level or lower than those observed previously in Mediterranean regions indicating the absence of techno-logically enhanced naturally occurring radioactive material (TENORM) activities in the area. Similar results were observed for the 232Th-series radionuclides and 40K in the water column in comparison with the relevant literature on the Mediterranean Sea. The calculated ratios of 238U—232Th and 40K—232Th verified the lack of TENORM contribution in the Saronikos Gulf. Finally, a rough estimation was attempted concerning the residence times of fresh water inputs from a treat-ment plant of domestic wastes (Waste Water Treatment Plant of Psitalia) showing that fresh waters need a maximum of 15.7+7.6 d to be mixed with the open sea water