Source, Characterization and Analysis Methodology of Microplastics in River Sediment: A Literature Review

Abstract

Microplastic pollution has gained global attention as an emerging environmental issue considering ambiguity, chemical inertness, and adverse impact. This study illustrates significant sources of microplastics and their pathways to the river sediment. Degradation and biofouling- two concrete terms related to the fate of microplastics in the aquatic environment are briefly explained in this study. Moreover, this study summarizes the outcomes and methodologies of some peer-reviewed articles on microplastics in river sediment. The result indicates great geographical variation in the concentration of microplastics around the globe. High concentration of microplastics was recorded in Wen- Rui Tang river, China, with an average abundance of 32947±15342 items/kg, whereas in the Qin river, the concentration of microplastics ranges from 0 to 97 items/kg only. Fibers, transparent and small-sized microplastics are predominant in shape, color, and size, respectively, in most studies. In terms of chemical composition, Polyethylene (PE) and/or Polypropylene (PP) are the dominant types of microplastics. However, a wide variation in technical approaches for microplastic analysis is observed in various studies. This study includes comparative discussion on different sampling methods and tools, benefits and drawbacks of various chemicals used for digestion and density separation, as well as ease and difficulties of different spectroscopy. Last but not least, some recommendations are proposed in the conclusion of this study for the advancement of research on microplastics in the future.