VERTICAL PARTICLE FLUXES IN THE LIGURIAN SEA

Since 1987, we have monitored the vertical flux of particles regularly at two time-series stations in the Ligurian Sea. Automated sediment t raps were used to collect samples at several depths, particularly at 8 0-100 m, 200 m and 1000 m. Vertical particle fluxes are relatively low in this open ocean region. In the upper 200 m, the annual mass flux w as 30 to 34 g m-2 y-1, and total carbon flux ranged from 5.1 to 7.6 g m-2 y-1. The export production (i.e. POC flux at 200 m) was 4.0 g m-2 y-1. Fluxes varied substantially over time, their patterns being relat ed to both the seasonality of the physical environment (water column m ixing in winter) and biological activity (spring phytoplankton bloom). Important quantitative and qualitative changes with depth were observ ed. The organic C:N atom ratio increased with depth (from 7.5 to 9.4), which indicates a rapid degradation of biogenic material.