Particle Fluxes and Transport Proceses Along the Continental Margins and in Deep Sea Environments.

Assessing processes involved in particle dynamics in the marine environment is an important step in order to understand the role of oceans in the global cycle of carbon and related elements. The sinking of particles represents one of the most important processes of exchange from the upper to deep ocean, and the export of organic carbon, produced by phytoplankton in the photic layers, gives the estimation of the efficiency of the biological pump. In the framework of several national and international projects, vertical fluxes of particulate matter and their biogenic components were analysed in the Adriatic and Ionian seas and in the Sicily strait, below the photic layer and near the bottom to define the principal processes affecting the dynamics of suspended matter in the open sea and along the continental margins. In open seas, the pool of particulate organic carbon is mainly determined by autotrophic production occurring in the upper layer of the water column, supported by the seasonal mixing, deep convection events and coastal-offshore exchange. The export of particles depends on production, consumption and decomposition controlled by physical and biological processes with high seasonal and interannual variability. Near the sea floor, advective transport and resuspension of bottom sediment influence the fluxes. In the Southern Adriatic, the Bari Canyon is an efficient conduit in delivering suspended sediment from the continental shelf to the deep basin.