Are we underestimating floating microplastic pollution? A quantitative analysis of two sampling methodologies

Area of Science:

• Environmental Science
• Ecotoxicology
• Analytical Chemistry

Background:

• Microplastics (MPs) are ubiquitous environmental contaminants in aquatic ecosystems.
• Accurate quantification of MPs is crucial for understanding their ecological impact.
• Sampling methodology is a critical determinant of reported MP abundance.

Purpose of the Study:

• To quantitatively compare microplastic abundance and characteristics between trawl and bulk sampling methods.
• To provide methodological recommendations for future microplastic research.
• To offer a general overview of microplastic abundance and differences based on sampling procedures.

Main Methods:

• A meta-analysis of 67 published investigations comparing trawl and bulk sampling methods for microplastics.
• Quantitative analysis of microplastic abundance, morphology, polymer types, and size ranges.
• Statistical comparison of data obtained from different sampling techniques.

Main Results:

• Bulk sampling methods reported significantly higher microplastic abundance (3500 times greater) compared to trawl methods.
• Microplastic morphological types and polymer compositions were statistically influenced by the sampling tool used.
• Trawl sampling significantly underestimated the abundance of smaller microplastic fractions.

Conclusions:

• The choice of sampling method critically affects microplastic quantification and characterization.
• Trawl methods may lead to an underestimation of microplastic pollution, particularly for smaller particles.
• Combining both bulk and trawl sampling methods is recommended for comprehensive microplastic data collection.