Transport and characterization of microplastics in inland waterways

Abstract

Microplastic pollution in floodplains and river channels in 14 locations at six sites along three rivers in Virginia was measured to test the hypotheses that microplastics concentrate in floodplains, exist as larger aggregates with other natural and synthetic particles, and may be different than ocean microplastics. The results show that (1) microplastic concentrations were generally just as high or higher in the floodplain than in the stream channel, (2) microplastics aggregated with natural sediment particles into the “heteroaggregates” predicted theoretically, (3) microplastics were larger in the floodplain than in the stream channel with a wider particle size distribution, (4) microplastic particles were 80 % fragments, 15 % spherical particles, and 5% fibers, and (5) chemically identified microplastics were composed of common packaging plastics that were heavily oxidized or hydrolyzed. The shape and chemical compositions of microplastic particles found was very similar to those observed in and around other rivers studied in the literature but different from the ocean environment. The floodplain could be used to capture river microplastics.