[Occurrence Characteristics and Influencing Factors of Microplastics in Surface Water, Sediments, and Benthic Macroinvertebrates in Huangbai River].

Microplastics are emerging as a novel environmental contaminant and pose a substantial threat to riverine ecosystems. This research focused on the Huangbai River, employing field sampling, laboratory experiments, and statistical analyses during April and July 2023. The objective of this study was to clarify the magnitude of microplastic contamination in surface water, sediment, and the benthic macroinvertebrate community. The findings indicated that the average abundance of microplastics in surface water was （7.33±4.66） n·L^-1, primarily consisting of fibrous and dark-colored particles with sizes ranging from 100 to 1 000 μm. In surface water, the prevalence of microplastics during the summer exceeded that observed in the spring season. The microplastics within the sediment exhibited an average abundance of （1.47±0.65） n·g^-1, primarily constituted by fiber and fragment-shaped particles, both black and colored, with sizes ranging from 100 to 1 000 μm. Benthic macroinvertebrates demonstrated an average microplastic abundance of （1.99±1.25） n·ind^-1 and （20.45±20.57） n·g^-1 in spring and（1.93±1.38） n·ind^-1 and （24.93±32.1） n·g^-1 in summer, respectively, featuring predominantly fiber-shaped particles, encompassing both black and colored particles, with sizes below 500 μm. A significant correlation was discerned between the characteristics of microplastics within organisms and their ambient environment. Redundancy analysis （RA） revealed a positive correlation between the abundance of microplastics in filter-feeding organisms and the concurrent presence of microplastics in the water during both spring and summer. In the case of shredders, microplastic abundance exhibited a positive correlation with flow velocity in spring and manifested a positive association with sedimentary microplastic abundance in summer. In spring, the abundance of microplastics in predators exhibited a negative correlation with water temperature, while in scrapers, microplastic abundance correlated positively with water depth. In conclusion, this study indicated the widespread contamination of microplastics in surface water, sediment, and benthic macroinvertebrates in the Huangbai River, underscoring that the ingestion of microplastics by benthic macroinvertebrates was influenced by various factors, including their feeding habits and environmental conditions.