Mapping Microplastic Movement: A Phase Diagram to Predict Nonbuoyant Microplastic Modes of Transport at the Particle Scale

Environmental Science & Technology, Journal Year: 2024, Volume and Issue: unknown

Published: Sept. 28, 2024

Microplastics pose numerous threats to aquatic environments, yet understanding their transport mechanisms remains limited. Drawing from natural sediment research provides valuable insights address this knowledge gap. One key dimensionless number used describe is the stage, referring ratio between flow shear velocity and particle settling velocity. However, variations in physical properties, such as shape density, raise concerns about applicability of existing theories microplastics. To challenge, we employed a modeling approach, examining 24 different nonbuoyant microplastic particles turbulent open channel flow. Utilizing 3D tracking, total 720 trajectories were recorded analyzed. Microplastic exhibited modes akin sediments, including rolling/sliding, saltation, suspension. The stage strongly correlated with these modes, well mean forward position water column. Notably, emerged critical factor influencing dynamics. Due lower velocity, fibers tended stay closer surface velocities compared spheres. Based on laboratory results, new phase diagram for microplastics introduced analogous an sediments.

Language: Английский

Numerical plastic transport modelling in fluvial systems: Review and formulation of boundary conditions

Water Research, Journal Year: 2024, Volume and Issue: 273, P. 122947 - 122947

Published: Dec. 18, 2024

In recent years, it has become clear that plastic pollution poses a significant threat to aquatic environments and human health. Rivers act as entry points for land-based waste, while certain fraction of entrained plastics is carried into marine environments. As such, the accurate modelling transport processes in riverine systems plays crucial role developing adequate remediation strategies. this paper, we review two main multiphase flow numerical approaches used modelling, comprising Lagrangian Transport Models (LTMs) Eulerian (ETMs). Although LTMs ETMs can be regarded complementary equivalent approaches, focus on trajectories individual particles, whereas represent behaviour particles terms their mass or volume concentrations. Similar results are expected, our shows models yet improved, specifically with respect formulation implementation boundary conditions, interactions channel bed, river bank, free surface, well biota. We anticipate an these conditions will allow better representation different modes, including bed load, suspended surface load. Finally, provide suggestions future research directions, novel threshold detachment plastics, hope inspire community, thereby triggering new developments rapidly advancing field modelling.

Language: Английский