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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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Extraction of microplastics from sediment matrices: Experimental comparative analysis
Mel Constant1, Gabriel Billon2, Noémie Breton2
1Univ. Lille, Institut Mines-Télécom, Univ. Artois, Junia, ULR 4515 - LGCgE, Laboratoire de Génie Civil et géo-Environnement, F-59000 Lille, France.
Journal of Hazardous Materials
|July 15, 2021
Summary
Extracting microplastics from sediments is challenging. Sodium iodide (NaI) shows promise for dense polymers, but a universal method for all microplastic types and sediments is still needed.
Area of Science:
- Environmental Science
- Analytical Chemistry
- Polymer Science
Background:
- Microplastics (<5 mm) are widespread pollutants in marine and terrestrial environments.
- Separating microplastics from sediment and soil matrices presents significant analytical challenges.
- Standardized methods for microplastic extraction are lacking, hindering comparability of research findings.
Purpose of the Study:
- To evaluate the efficiency of various extracting solutions (ESs) and isolation methods (IMs) for microplastic separation from sediments.
- To identify optimal protocols for different polymer types (low and high density) and sediment characteristics.
- To address the need for improved and comparable microplastic monitoring techniques.
Main Methods:
- Tested 18 combinations of six extracting solutions (oil, water, oil-in-water, NaCl, oil-in-NaCl, NaI) and three isolation methods (hand stirring, centrifugation, aeration).
- Evaluated extraction efficiencies for fine and coarse sediments with low (PE, PE-ABS) and high density polymers (PET, PES, PA).
- Assessed extraction rates for different microplastic shapes (pellets, fragments, fibers).
Main Results:
- Isolation methods did not significantly impact extraction efficiency.
- Most ESs achieved good extraction (84 ± 17%) for light polymers, except oil.
- Sodium iodide (NaI) demonstrated the highest efficiency (71 ± 17%) for dense polymers.
- Fiber extraction efficiency was lower than pellets and fragments across tested ESs.
- Overall extraction efficiencies were lower than literature values, with issues in collecting floating plastics.
Conclusions:
- No single robust protocol exists for extracting all microplastic types and forms from fine sediments.
- NaI is effective for dense polymers, while other solutions work for lighter ones.
- Further research is needed to account for particle interactions and electrostatic properties for improved microplastic extraction methods.
