CS-137 AS A TRACER OF THE CATALAN CURRENT

A number of nuclear power installations located in the north-western M editerranean (NWM) area are known to enhance Cs-137 levels in various marine compartments. The nuclear fuel reprocessing plant at Marcoule ( France) has been reported to originate a significant increase of Cs-13 7 in Rhone river waters and sediments because of the discharge of low- level liquid radioactive waste. This radionuclide may be used as a tra cer of oceanographic processes in the NWM; in fact, Cs-137 Of Rhone ri ver origin has been detected in the Gulf of Lions by several authors. The results reported in this work correspond to various transect exper iments in waters of the Catalan Sea and show that: (i) surface salinit y measurements confirmed the presence of the Catalan current in the Ca p de Creus area; (ii) the 1991 Cap de Creus transect showed clearly th e presence of Cs-137 above a baseline level of 4.3 +/- 0.2 Bq . m(-3); (iii) the 1991 Cap de Salou transect showed elevated levels towards th e coast; (iv) the 1992 Cap de Creus transect showed no iv structure at all. Therefore, it was concluded that traces of Cs-137 from the Marco ule nuclear fuel reprocessing plant were transported by the Catalan cu rrent and were detectable in the Catalan Sea with a complex spatio-tem poral structure.