Spatio and temporal dynamics of microplastic fluxes within the watercourses of a peri-urban watershed

The intensity of human activity drives the leakage of plastics into the environment. However, distinguishing the impact of each land use type on the aquatic ecosystems is challenging. The fate and transfer of this pollution once it reaches the rivers is also poorly understood. This study focuses on the watercourses of a small peri-urban catchment (Avenelles, 45 km², 70 km east of Paris). It monitors the dynamics of MP fluxes during flood events as well as dry weather periods for a better understanding of the influence of hydrological conditions. Moreover, microplastics are sampled at different sub-catchments with variable land covers (intensive agriculture, forest, urban) in order to differentiate their impact. Samples were collected using the Universal Filtering Object: a plastic-free pumping system coupled with filtration in series (300 and 10 µm). In addition, sediment traps were used to capture suspended solids. Microplastic sampling was combined with different physico-chemical parameter measurements (suspended solids, flowrate, conductivity etc.). Samples underwent a pre-treatment protocol to remove the organic and mineral fractions and were analysed by Fourier transform infrared µspectroscopy (automated imaging – data treatment via siMPle software). Estimated fluxes at the outlet of the catchment are 15 to 50 times greater at wet periods in comparison to dry weather. In opposition to the outlet of the catchment containing primarily polyethylene (80 Also see: https://micro2024.sciencesconf.org/559517/document