Date-prints macroplastics - Microlax packagings

Inventory of Microlax packaging collected in the Seine estuary showing date-prints. Rivers are a major transport pathways for plastics from land into the ocean. At the land-ocean interface, estuaries are very specific hydrodynamic systems. However, very little is known about the transport dynamic of plastics in estuaries. Tidal regimes, winds and the mixing of fresh and salt water make the transfer dynamic of plastics complex and nonlinear. Microlax packagings were systematically investigated in different riverbanks of the Seine estuary to identify the share of “old” and “fresh” litter transiting through the estuary toward the ocean. Results show that up to 70% of Microlax were “old” plastic items probably related to the meandering dynamic of the river at large time and space scales, and hydrodynamic conditions at smaller scales. This contributes together to increase the residence time of plastics into the estuary up to decades with numerous transport, deposit and remobilization cycles. It finally may results in the fragmentation of macroplastics into microplastics well before they reach the ocean.