ND ISOTOPES AS TRACERS IN WATER COLUMN PARTICLES - THE WESTERN MEDITERRANEAN-SEA

Measurements of Nd isotopic ratios in sediment trap materials are reported on samples obtained from the western Mediterranean Sea margin (Gulf of Lions). Trap samples from two different seasons were examined. For the summer-autumn series (October), the fluvial inputs are relatively weak, and the Saharan aerosol influence is clearly identified in the particles trapped in the surface water (0-100 m). Isotopic ratios can be explained by a mixture of low values, corresponding to Saharan detrital aerosol particles, with higher radiogenic ratios similar to values reported earlier for the Mediterranean watermass, which are carried by biogenic particulate components. On the other hand, bottom layers are more probably invaded by particles coming from the shelf and the neighbouring rivers. For the winter-spring series (March), high particle fluxes coming from the distant Rhône river and advected along the shelf and margin by ocean currents, are the dominant component in the surface and intermediate trap-samples. However, the near-bottom particulate flux and the sediments reflect the more local river signature. © 1990.