Comparison of two pump-based systems for sampling small microplastics (>10 μM) in coastal waters

Area of Science:

• Environmental Science
• Marine Biology
• Analytical Chemistry

Background:

• Microplastics (MPs) are pervasive environmental pollutants with potential harm to aquatic life.
• Limited data exists on the abundance and characteristics of smaller microplastics (<300 μm) in marine environments.
• Standardized sampling methods are crucial for accurate microplastic assessment.

Purpose of the Study:

• To compare the efficacy of two filter pump devices, AAU-UFO and KCD, for sampling small microplastics (>10 μm).
• To analyze the concentration and composition of microplastics in the Gulf of Bothnia.
• To contribute to harmonizing microplastic sampling methodologies.

Main Methods:

• Coastal water sampling at six sites in the Gulf of Bothnia using both AAU-UFO and KCD filter pumps.
• Analysis of microplastic concentration and composition using FPA-μFTIR imaging.
• Characterization of microplastic size, shape, and polymer type.

Main Results:

• Both AAU-UFO and KCD pumps yielded comparable median microplastic concentrations (117-162 MP/m³).
• Fragments were the predominant microplastic shape, with polyester, polyethylene, and polypropylene being the most common polymers.
• Microplastics smaller than 300 μm constituted over 90% of the total microplastic abundance, with concentrations significantly higher than previously reported using manta nets.

Conclusions:

• Both AAU-UFO and KCD filter pumps are effective and comparable for sampling small microplastics (>10 μm) in coastal waters.
• The study highlights the critical importance of sampling microplastics <300 μm for accurate environmental monitoring.
• Findings support the harmonization of microplastic sampling techniques for improved risk assessment and management strategies.