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Experimental Study on the Incipient Motion of Microplastic Particles with Different Shapes, Sizes, and Densities on a Live Sediment Bed
Summary
Researchers experimentally determined the conditions under which 65 groups of microplastic particles of varying shapes, sizes, and densities begin to move on a sediment bed, finding that after accounting for friction differences and hiding effects, microplastic motion follows the classical Shields curve used for natural sediment transport.
The present study aims to add a novel data set on the incipient motion of a broader array of microplastic particles, on a live sediment bed comprised of finer sediment grains than those used by WS19. The incipient motion of 65 microplastic particle groups, having both regular (57) and irregular (eight) shapes, are investigated experimentally in a circular flume. Regular shapes considered include spheres, circular cylinders, circular disks, square plates, cubes, square prisms, rectangular prisms, tetrahedrons, and fibers. The present data set is combined with another from the literature, and the incipient motion conditions of the collective particles are systematically analyzed. After accounting for (1) differences in static friction as well as (2) hiding-exposure effects, reasonable agreement with the classical Shields curve for the incipient motion of sediments is achieved. These results provide deeper understanding of the fundamental transport properties and patterns of microplastic particles, on which is based the development of any successful management strategies.
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