Mapping Microplastics Around the World with NASA Satellites

Category Health

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University of Michigan researchers found a way to track microplastics in the world's oceans using NASA satellites to accurately detect and monitor these particles. This technique will significantly help in ocean remediation and cleanup efforts.

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Ocean plastics have become a major source of concern for evironmental conservationists and public health professionals in recent years, and there hasn't been a good way to track how these plastics are moving or their concentrations. But now, researchers from the University of Michigan have developed an ingenious way to track the ebb and flow of these microplastics around the world thanks to NASA satellites.

Large pieces of plastic break down into microplastics due to chemical and physical processes

Microplastics are the remnant pieces of larger plastics that have disintegrated over time due to chemical and physical processes, and are typically measured as less than 5mm in size. The underlying plastic compounds remain intact even as the plastic fiber or particle gets physically smaller, and plastics do not chemically decompose.

This makes them especially hard to track, even as the potential long-term health concerns for marine and animal life that ingest them, including humans, especially pressing. But how do you map the location of a patch of 5mm plastic particles in the ocean when 70% of the planet is covered in water? .

Microplastics have the same effect on marine life as ingesting plastic pollutants

That is the challenge that University of Michigan (UM) marine engineer Yulin Pan and his colleagues set out to solve, and with the help of NASA's Cyclone Global Navigation Satellite System (CYGNSS), it looks like they've found a real, effective mapping solution that can significantly help in ocean remediation and cleanup efforts.

"In general, there are insufficient data about microplastics concentration in the ocean," Pan said, according to Scientific American. "That is one of the reasons that we really want a remote sensing technique, to have a general understanding." .

Microplastics are able to absorb pollutants while in the ocean

This is especially needed since the current method, trawling the ocean with nets to detect microplastic levels, is tragicomically insufficient to the scope of the problem. The solution that the CYGNSS researchers developed, described in a new paper in Scientific Reports, takes a much wider view than an ocean-going trawler, instead taking a 300-mile satellite's-eye view of the problem.

Originally designed to track wind over the oceans to help scientists better understand how hurricanes form and predict their development, CYGNSS data provided a key insight for the researchers in 2021, who saw that data from the system showed an unexpected smoothness in the waves of an area of the Pacific Ocean they were not expecting.

The University of Michigan researchers developed a technique by using the CYGNSS satellite that can track these microplastics concentrations around the world

This area of smoothness was later found to line up with the location of the Great Pacific Garbage Patch, and they were able to find other plastic concentrations in a similar fashion but were unable to figure out what was creating the smoothness they were seeing.

"The original idea for this detection technique really arose from a related technique that's used with satellites to track oil spills," UM Climate and Space Professor Christopher Ruf said last year. "They do that by looking at how the presence of the oil suppresses the roughness of the ocean, so we just expanded on that idea." .

More than 8 million tons of plastic ends up in the ocean each year

"The wind over the water causes these little ripples and you can easily see them with radars and satellites," Ruf added. "We looked at how windy it was using other satellite measurements and predicted from that how rough the surface should be, and then we made direct measurements of how rough it actually was with those satellites.\n .

Step two was to use reflective materials like leaves or particles on the ocean surface, like a foam cup floating on the surface, to create a very different reflection. Pan and the team hoped that these materials will have a different effect than the smoothness of the plastic patches, and when they compared the two sets of data, they showed that their hope had been fulfilled. Microplastic collections show up as a reduction in the roughness of the CYGNSS data, and the team showed that they can use CYGNSS to accurately detect and track these microplastics patches around the world.

NASA satellites can measure patterns of the ocean's surface to indicate the presence of microplastics

In the same paper, the team showed that over a three-month study period in 2021, they were able to use the satellite system to accurately track the movement of the Great Pacific Garbage Patch from satellites.

"Our approach shows that a global satellite-based portfolio of synthetic aperture radars can be the way in the future for researchers and policymakers to get a better global perspective on the variable and dynamic trajectories of microplastics in global oceans," Pan said.

The CYGNSS system itself is made up of 8 small, low-altitude satellites that were launched in orbit in late 2016, and is designed to provide better, more comprehensive wind speed data for hurricane prediction and understanding than could be obtained by a network of larger, geosynchronous satellites. But the new application of CYGNSS that Pan and his team have developed could be just as, if not more, impactful in the long term.

As plastic pollution continues to spread around the world and more and more microplastics end up in our environment, the importance of being able to track the size, shape and movement of these particles, and the responsibility of cleaning them up, is only growing. This new detection method developed by Pan and his team is a major step in being able to better track, monitor and ultimately mitigate the microplastic crisis before it gets even worse.

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