Written by Chris Ruf
Plastic is the most common type of debris floating in the world’s oceans. Waves and sunlight break much of it down into smaller particles called microplastics – fragments less than 5 millimeters across, roughly the size of a sesame seed.
To understand how microplastic pollution is affecting the ocean, scientists need to know how much is there and where it is accumulating. Most data on microplastic concentrations comes from commercial and research ships that tow plankton nets – long, cone-shaped nets with very fine mesh designed for collecting marine microorganisms.
But net trawling can sample only small areas and may be underestimating true plastic concentrations. Except in the North Atlantic and North Pacific gyres – large zones where ocean currents rotate, collecting floating debris – scientists have done very little sampling for microplastics. And there is scant information about how these particles’ concentrations vary over time.