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Updated: Jul 15, 2025
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Sampling, Sorting, and Characterizing Microplastics in Aquatic Environments with High Suspended Sediment Loads and Large Floating Debris
Published on: July 28, 2018
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Investigations on microplastic infiltration within natural riverbed sediments
Mirco Mancini1, Simona Francalanci1, Lorenzo Innocenti1
1Department of Civil and Environmental Engineering, University of Florence, Via S. Marta 3, 50139 Florence, Italy.
The Science of the Total Environment
|September 23, 2023
Summary
Riverbed sediment characteristics, not hydraulic load or time, primarily control microplastic (MP) infiltration depth. MP size relative to sediment grain size is key for understanding MP transport in freshwater systems.
Area of Science:
- Environmental Science
- Environmental Chemistry
- Geosciences
Background:
- Rivers act as significant pathways for microplastic (MP) transport to marine environments.
- MP interaction with riverbed sediments is known, but factors influencing their mobility in the hyporheic zone remain unclear.
Purpose of the Study:
- To investigate how different sediment sizes affect the mobility of common microplastics (Polyethylene terephthalate spheres/ellipsoids, polystyrene fragments, polyamide fibers).
- To determine the influence of hydraulic loads and time scales on microplastic infiltration and distribution within riverbed sediments.
Main Methods:
- Experimental investigation of microplastic mobility in various sediment layers.
- Controlled application of different hydraulic loads (HL) and time scales (t).
- Analysis of microplastic distribution and maximum infiltration depth within sediment cores.
Main Results:
- The ratio of microplastic diameter to sediment grain size is the primary factor governing MP infiltration.
- Maximum MP infiltration depth was independent of hydraulic load and time.
- Hydraulic load influenced the percentage of MPs penetrating the surface layer and their distribution within the first 10-15 cm.
- No MPs were found below 20-25 cm, with only PET spheres detected at these depths.
Conclusions:
- A model based on suffusion theory can predict maximum microplastic infiltration depth.
- Understanding the geometrical and hydrodynamic properties of riverbed sediments is crucial for characterizing MP transport in freshwater systems.
