Synthetic microfibers driven by turbidity currents: Transition from smooth bed to macro-roughness

Area of Science:

• Environmental Science
• Fluid Dynamics
• Ecotoxicology

Background:

• Turbidity currents are key in transporting microplastics (MPs) in aquatic systems.
• Microfiber (MF) transport dynamics are less understood due to their unique physical properties.
• MFs pose distinct challenges in aquatic environments compared to other MPs.

Purpose of the Study:

• To investigate microfiber transport by turbidity currents over various bedforms.
• To assess the influence of bed roughness and water depth on MF behavior.
• To develop a predictive model for microfiber transport.

Main Methods:

• Lock-exchange flume experiments were conducted.
• Experiments varied bed layer conditions (micro to macro-roughness) and water depths.
• Microfiber transport and deposition were analyzed under different flow conditions.

Main Results:

• Bed roughness and water depth significantly affect turbidity current velocity and MF accumulation.
• Despite settling tendencies, MFs traveled farther due to streamline alignment, especially smaller diameters.
• A novel non-dimensional model was developed to predict MF transport.

Conclusions:

• MF transport is complex and influenced by hydrodynamic and environmental factors.
• The developed model offers insights into microfiber fate in aquatic systems.
• This research is crucial for understanding plastic pollution dynamics.