Pore-Scale Insights into Microplastic Fiber Transport and Retention in Porous Media

Area of Science:

• Environmental Science
• Soil Science
• Materials Science

Background:

• Agricultural soils act as sinks for microplastic fibers (MPFs).
• Limited understanding exists regarding MPF transport and behavior within soil environments.
• Polypropylene microfibers (MPFs) are common environmental contaminants.

Purpose of the Study:

• To investigate the transport and retention mechanisms of microplastic fibers in soil-like porous media.
• To determine the influence of MPF dimensions and elasticity on their mobility.
• To assess how fiber entrapment affects pore-scale flow dynamics.

Main Methods:

• Utilized a microfluidic cell to simulate soil porous media.
• Tracked polypropylene microfibers (20-150 μm) under controlled flow conditions.
• Analyzed the effects of fiber size and flexibility on transport and retention.

Main Results:

• Fiber transport is highly dependent on size and flexibility.
• Fibers longer than 50 μm exhibited significant retention.
• Shorter fibers followed preferential flow paths, experiencing higher velocities.
• Trapped fibers altered pore-scale flow patterns, differing from spherical particle behavior.

Conclusions:

• Microplastic fiber behavior in porous media is complex and influenced by physical properties.
• Retention mechanisms for fibers differ from those of spherical particles.
• Even small amounts of trapped fibers can significantly impact soil hydraulic properties.
• Further research is needed to improve models predicting MPF behavior in soil systems.