Julien’s work is focused and the presence, source and fate of nanoparticles in the environment. To achieve his goal, he is developing innovative coupled analytical and experimental methods to characterize the different properties specific to nanoparticles (size, size distribution, shape, surface, etc.) and their evolution at the natural interfaces specific to the Land-to-Sea continuum, such as soils, estuary and floe. Since 2015, Julien has been particularly interested in nanoplastics in the environment and the challenges related to the plastic pollution. He is currently co-supervising several PhD students and Post-Docs on this multi-disciplinary theme and is leading several national and international projects on nanoparticles and nanoplastics. One of the specific Julien’s attention is the ability of the nanoscale materials to transport contaminants and reciprocally to use this “Trojan Horse” property to trace their source and fate in the environment.