The Environmental and Paleo-Environmental and Oceanic Laboratory of the CNRS and the University of Bordeaux (UMR 5805) has been working for several years on plastic contamination in the marine environment and the impact of microplastics on the health of aquatic organisms. As part of the TARA Europe campaign, the aquatic ecotoxicology team proposes to collect microplastics (1-5 mm) on the eleven largest rivers in Europe in order to evaluate and map the fluvial contributions and quantify the pollutants and the toxic load carried by these plastics towards the marine environment. This study will better assess the risks to the marine ecosystems of microplastics brought by rivers.