UNUSUAL PO-210 PB-210 RATIOS IN THE SURFACE-WATER OF THE GULF-OF-LIONS/

Concentrations of Po-210 and Pb-210 have been measured in sea water co llected in the Grand Rhone Canyon. Concentrations of Pb-210 are at sim ilar levels to those found in other Mediterranean seawater samples, an d are at the levels which would be expected in comparison with global sea water data. The same applies to the Po-210 concentrations in sampl es from below 100 m depth. Surface samples from above 100 m have Po-21 0 at levels rather higher than expected, and their Po-210/Pb-210 ratio s are about 1 or more as compared with the usual open ocean ratio of a bout 0.5. These data can be interpreted as indicating another source o f supply of Po-210 to the surface layer in addition to the normal atmo spheric input. We suggest that an episodic advective particulate input , probably originating in the output of the Rhone river and perhaps in volving resuspension of fine particulates from the bottom sediments as a result of storm conditions, is the most likely candidate for this a dditional source. (C) Elsevier, Paris.