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The ocean is full of tiny plastic particles – we found a way to track them with satellites

Plastic fragments washed onto Schiavonea beach in Calabria, Italy, in a 2019 storm. Alfonso Di Vincenzo/KONTROLAB /LightRocket via Getty Images

The ocean is full of tiny plastic particles – we found a way to track them with satellites

Plastic fragments washed onto Schiavonea beach in Calabria, Italy, in a 2019 storm. Alfonso Di Vincenzo/KONTROLAB /LightRocket via Getty Images

The ocean is full of tiny plastic particles – we found a way to track them with satellites

Plastic fragments washed onto Schiavonea beach in Calabria, Italy, in a 2019 storm. Alfonso Di Vincenzo/KONTROLAB /LightRocket via Getty Images

The ocean is full of tiny plastic particles – we found a way to track them with satellites

Plastic fragments washed onto Schiavonea beach in Calabria, Italy, in a 2019 storm. Alfonso Di Vincenzo/KONTROLAB /LightRocket via Getty Images

Annual global production of plastic has increased every year since the 1950s, reaching 359 million metric tons in 2018. Much of it ends up in open, uncontrolled landfills, where it can wash into river drainage zones and ultimately into the world’s oceans.

Plastic fragments washed onto Schiavonea beach in Calabria, Italy, in a 2019 storm. Alfonso Di Vincenzo/KONTROLAB /LightRocket via Getty Images

Christopher Ruf, University of Michigan

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.

Two people lower conical nets off a research ship into the water.

Researchers deploy plankton sampling nets in Lake Michigan. NOAA, CC BY-SA

To address these questions, University of Michigan research assistant Madeline Evans and I developed a new way to detect microplastic concentrations from space using NASA’s Cyclone Global Navigation Satellite System. CYGNSS is a network of eight microsatellites that was launched in 2016 to help scientists predict hurricanes by analyzing tropical wind speeds. They measure how wind roughens the ocean’s surface – an indicator that we realized could also be used to detect and track large quantities of microplastics.

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