Substantial burial of terrestrial microplastics in the Three Gorges Reservoir, China

Abstract Hydropower dams impact the transport of microplastics from rivers to ocean. The Yangtze River is a large source plastics Here, we report microplastic concentrations and compositions across range size fractions for sediment samples collected in upper lower reaches Three Gorges Dam 2008, 2015, 2019 2020. We find gradual increase abundance over time, with preferential retention small-sized (<300 μm) dam reservoir sediments. Small accounted between approximately 44 90% identified microplastics, 82% all polyethylene particles, which were dominant polymer type. Our estimate total plastic mass load sediments suggests that retains as much 8048 ± 7494 tons yr ‒1 sediments, equivalent 47 44% flux