“We’d been taking these radar measurements of surface roughness and using them to measure wind speed, and we knew that the presence of stuff in the water alters its responsiveness to the environment,” Ruf said. The measurements have mainly been used to calculate wind speed near the eyes of hurricanes, but Ruf wondered whether they might have other uses as well. The key to the process is ocean surface roughness, which CYGNSS already measures using radar. Evans, the tracking method uses existing data from CYGNSS, a system of eight micro-satellites launched in 2016 to monitor weather near the heart of large storm systems and bolster predictions on their severity. Hurricane-tracking satellites set their sights on plastic pollutionĭeveloped by Ruf and U-M undergraduate Madeline C.
Single-point release data may also be useful to United Nations agency UNESCO, which has sponsored a task force to find new ways to track the release of microplastics into the world’s waters. The researchers are already in talks with Dutch cleanup organization The Ocean Cleanup on working together to validate the team’s initial findings. Ruf says the information could help organizations that clean up microplastics deploy ships and other resources more efficiently.
“What makes the plumes from major river mouths noteworthy is that they are a source into the ocean, as opposed to places where the microplastics tend to accumulate,” Ruf said. Often, the areas of accumulation are due to prevailing local water currents and convergence zones, with the Great Pacific Garbage Patch being the most extreme example. The researchers produced visualizations that show microplastic concentrations around the globe. “The microplastics data that has been available in the past has been so sparse, just brief snapshots that aren’t repeatable.” “It’s one thing to suspect a source of microplastic pollution, but quite another to see it happening,” Ruf said. The data also showed several brief spikes in microplastic concentration at the mouth of the Yangtze River-long suspected to be a chief source. Concentrations tend to be lower during the winter months, likely due to a combination of stronger currents that break up microplastic plumes and increased vertical mixing that drives them further beneath the water’s surface. Concentrations in the Southern Hemisphere reach their peak during its summer months of January and February. June and July, for example, are the peak months for the Great Pacific Garbage Patch, a convergence zone in the North Pacific Ocean where microplastic collect in massive quantities. The team found that global microplastic concentrations tend to vary by season, peaking in the North Atlantic and Pacific during the Northern Hemisphere’s summer months. Season changes in the Great Pacific Garbage Patch
“We’re still early in the research process, but I hope this can be part of a fundamental change in how we track and manage microplastic pollution,” said Chris Ruf, the Frederick Bartman Collegiate Professor of Climate and Space Science at U-M, principal investigator of CYGNSS and senior author on a newly published paper on the work. The technique is a major improvement over current tracking methods, which rely mainly on spotty reports from plankton trawlers that net microplastics along with their catch. The approach relies on the Cyclone Global Navigation Satellite System (CYGNSS) and can give a global view or zoom in on small areas for a high-resolution picture of microplastic releases from a single location. Now, University of Michigan researchers have developed a new way to spot ocean microplastics across the globe and track them over time, providing a day-by-day timeline of where they enter the water, how they move and where they tend to collect. The bits can harm sea life and marine ecosystems, and they’re extremely difficult to track and clean up. An estimated eight million tons of plastic trash enters the ocean each year, and most of it is battered by sun and waves into microplastics-tiny flecks that can ride currents hundreds or thousands of miles from their point of entry.
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