The microplastics They form when plastic waste in the ocean is broken down by sunlight and the movement of ocean waves. These tiny patches of plastic are harmful to marine organisms and ecosystems and can be carried hundreds or thousands of miles from the source by ocean currents, making them difficult to track and remove.
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Faced with this problem, researchers from University of Michigan They’ve developed a new way to detect and track microplastics in oceans around the world over time, providing a day-to-day timeline of where they enter the water, how they move, and where they tend to accumulate.
The approach depends on Cyclone Global Navigation Satellite System (Cygnss) from NASA, a constellation of eight small satellites that measure wind speeds over Earth’s oceans and provide information on the strength of hurricanes, and can provide a global view or zoom in on small areas to get a high-resolution picture of microplastic emissions from a single location.
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This technique is a significant improvement over current monitoring methods, which mainly rely on irregular reports from fishermen who use nets to catch plankton and track microplastics alongside them.
They change with the seasons
The team found that global concentrations of microplastics tend to vary seasonally, peaking in the North Atlantic and Pacific Oceans during the northern hemisphere summer months.
June and July, for example, are the peak months for the Great Pacific Garbage Patch, a convergence region in the North Pacific where microplastics accumulate in huge quantities.
Concentrations in the Southern Hemisphere reach their peak during the summer months of January and February. Concentrations tend to decrease during the winter months, possibly due to a combination of stronger currents that break up the microplastics and greater vertical mixing that carries them deeper below the water’s surface.
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The data also showed several short spikes in the concentration of microplastics at the shutter mouth Yangtze River, which has long been suspected to be a major source of this type of pollution.
The researchers produced visualizations showing concentrations of plastic particles around the world. Areas of accumulation are often due to prevailing local streams and areas of convergence, with the Great Pacific Garbage Patch being the most extreme example.
Chris Rove, a professor of space and climate sciences at the University of Michigan and principal investigator at Cygnss, says the information could help organizations that clean up microplastics deploy ships and other resources more efficiently.
The researchers are already in talks with Dutch cleaning organization The Ocean Cleanup to work together to validate the team’s initial findings. The data may also be useful to UNESCO, which has sponsored a working group to find new ways to track the release of microplastics into the world’s waters.
*With information from the University of Michigan
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