Characteristics and Potential Risks of Microplastics in Water, Sediment, and Fish Gut from the Heavily Sediment-Laden Yellow River, China

Abstract

Microplastics in aquatic ecosystems may have adverse effects on organisms of different trophic levels, especially in rivers with complex hydrodynamic conditions and high sediment concentrations. It is still unclear how fish with different feeding habits relate to the microplastics in sediment-laden rivers,  whether there are interspecific or spatial differences in characteristics. We investigated microplastic pollution in different environmental media and the gut of various fish species along the Yellow River mainstream . Microplastics were detected in all water, sediment, and fish gut samples, with mean abundance increasing from upstream to downstream. The abundance of microplastics ingested by fish varied between 2 and 80 items/individual, depending on habitat environment and feeding habit. The highest abundance occurred in omnivorous fish, followed by zooplanktivorous fish, carnivorous fish, phytoplanktivorous fish, and herbivorous fish. The microplastics in different media were predominantly small (< 1 mm, 45.4%), fibrous (92.9%), and blue (42.8%). The chemical composition is mainly polyethylene and polypropylene. High sediment concentrations accelerated microplastic fragmentation and sedimentation, small particle size are more harm to organisms. Trace metals and impurities were enriched on microplastic surfaces. Microplastic in fish gut was considerably influenced by population and population density,and pose a potential threat to human health.

Keywords: microplastic pollution, high sediment load, aquatic environment, freshwater fish, feeding habit