Particulate matter and organic carbon budgets for the Gulf of Lions (NW Mediterranean)

An analysis of sedimentological, sediment trap and hydrological data was pe rformed to investigate the transport and fate of particulate matter in the Gulf of Lions. The sedimentological properties outline the major sedimentar y units of the shelf (Rhone prodelta, mid-shelf mud belt, outer shelf) and slope. The geometry of these sedimentary units and the southwestwards incre ase of particulate fluxes on the slope highlight the influence of the gener al cyclonic circulation on the dispersion of land-derived particulate matte r. Considering the known input and output terms, budgets of particulate mat ter and organic carbon in the Gulf of Lions are proposed. Inputs were river supply, atmospheric deposition and primary production; outputs were sedime nt burial and advective export on the slope. Degradation of particulate org anic carbon in the water column and at the sediment-water interface was als o estimated. Mass and POC budgets were balanced within uncertainties. Never theless, these results illustrate the difficulty in establishing budgets ba sed on elements estimated at different time scales, for which the system is not necessarily in a steady state. (C) 2000 Ifremer/CNRS/IRD/Editions scie ntifiques et medicales Elsevier SAS.