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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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Buoyant microplastics in freshwater sediments - How do they get there?
Marziye Molazadeh1, Fan Liu1, Laura Simon-Sánchez2
1Aalborg University, Section of Civil and Environmental Engineering, Department of the Built Environment, Thomas Manns Vej 23, 9220 Aalborg Øst, Denmark.
The Science of the Total Environment
|December 1, 2022
Summary
Stormwater treatment ponds trap microplastics (MPs) in sediments, with uneven distribution. Their accumulation correlates with organic matter, suggesting MPs are retained, preventing downstream pollution.
Area of Science:
- Environmental Science
- Environmental Chemistry
- Water Quality Management
Background:
- Microplastics (MPs) are emerging environmental pollutants.
- Stormwater treatment ponds are designed to mitigate pollution entering natural environments.
- Understanding MP fate in these systems is crucial for environmental protection.
Purpose of the Study:
- To investigate microplastic accumulation in stormwater treatment pond sediments.
- To quantify MP abundance, distribution, and characteristics.
- To elucidate MP transport and deposition mechanisms within the pond.
Main Methods:
- Analysis of 13 sediment samples for microplastics down to 10 μm.
- Characterization of MP polymer types (e.g., polypropylene, polyethylene).
- Computational Fluid Dynamics (CFD) modeling of MP transport.
Main Results:
- Average MP abundance: 11.8 μg kg-1 (mass) and 44,383 item kg-1 (number).
- Uneven MP distribution (up to two orders of magnitude variation).
- Buoyant MPs constituted the majority of mass (95.4%) and number (83.5%).
- MP content correlated with organic matter and silt, not spatial location.
- CFD modeling indicated advection and dispersion drive MP-sediment contact.
Conclusions:
- Stormwater treatment ponds can retain microplastics, reducing downstream aquatic pollution.
- Accurate MP quantification requires numerous, well-distributed sediment subsamples.
- MP deposition is influenced by sediment properties rather than spatial patterns.
- Transport mechanisms like advection and dispersion are key to MP settling in ponds.
