Research progress on pollution and toxic effects of microplastics in freshwater environment

By summarizing the distribution status and research progress of microplastics in the freshwater environment, the abundance, type, particle size, color, shape and influence factors of microplastics in the freshwater environment were analyzed, and the toxic of microplastics on different trophic organisms in freshwater environment ecosystem were summarized. The results showed that the microplastics distribution in the freshwater bodies was affected by human activities, hydrological characteristics, seasons and microplastics types. Freshwater with more human activities, poor hydrodynamic conditions and more precipitation was seriously polluted by microplastics, and the occurrence of microplastics with different densities was different in environmental media. The toxicity of microplastics was closely related to their concentration, particle size and type, and affected the feeding, growth and reproduction ability of aquatic organisms through the enrichment and carrying of chemical pollutants in organisms. The abundance of microplastics in the freshwater environment in China was higher than that in other countries. It was suggested to gradually carry out the investigation and monitoring of microplastics flux in the freshwater environment and river into the sea. The present microplastics research on the toxic effect at home and abroad mainly focused on phytoplankton, Daphnia magna, mussels and zebrafish, which still could not meet the requirement of the microplastics ecological and health risk assessment. It was urgent to research the microplastics toxicity effect of native organisms at different trophic levels in China, so as to provide scientific and technological support for the establishment of the microplastics environmental benchmark in the freshwater environment in the future.