The project has been designed to provide reliable data on concentrations, fluxes and chemical species of trace elements entering and leaving the Gironde estuary due to different hydrological situations. The existing, well-working long-term monitoring of Cd-pollution along the main tributary will be intensified and completed. It will then monitor-the fluxes of 11 eco-toxic trace elements (As, Sb, Cr, Ni, Cu, Zn, Cd, Hg, Mo, Sn, Pb) into the Gironde by all relevant tributaries, ensuring improved localisation and evaluation of individual sources. Emphasis will be laid on a detailed characterisation of the species of these elements along the complete salinity gradient, considering contrasting hydrological situations and especially the different zones of the stable turbidity maximum. This will provide essential information on the trace element distribution and transformation due to the fundamentally changing milieus in the continuum river-estuary-coast. It will also improve our understanding of mechanisms and processes responsible for the fixation and remobilization of pollutants in these eco-systems. Due to an interdisciplinary scientific co-operation, the project will complete the analytical programme of an eco-toxicity study on the possibility of re-cultivating mussels in the estuary. This co-operation represents the great opportunity to characterise the bio-accumulation of trace elements under real conditions of food production.