Dispersal and transport of microplastics in river sediments

Rivers are viewed as major pathways of microplastic transport from terrestrial areas to marine ecosystems. However, there is paucity of knowledge on the dispersal pattern and transport of microplastics in river sediments. In this study, a three dimensional hydrodynamic and particle transport modelling framework was created to investigate the dispersal and transport processes of microplastic particles commonly present in the environment, namely, polyethylene (PE), polypropylene (PP), polyamide (PA), and polyethylene terephthalate (PET) in river sediments. The study outcomes confirmed that sedimental microplastics with lower density would have higher mobility. PE and PP are likely to be transported for a relatively longer distance, while PA and PET would likely accumulate close to source points. High water flow would transport more microplastics from source points, and high flow velocity in bottom water layer are suggested to facilitate the transport of sedimental microplastics. Considering the limited dispersal and transport, the study outcomes indicated that river sediments would act as a sink for microplastic pollutants instead of being a transport pathway. The patchiness associated with the hot spots of different plastic types is expected to provide valuable information for microplastic source tracking. 0 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study established a model to investigate the dispersion and transport processes of common microplastics in river sediments, finding that lower density microplastics are more mobile and different types of plastics exhibit varying levels of mobility in sediment. The study results suggest that river sediments may act as pollution sinks for microplastics.