Scientists and researchers from the University of Michigan have developed an innovative method to use satellite data from the National Aeronautics and Space Administration (Nasa) to track the movement of tiny pieces of plastic in the ocean.
Microplastics are formed when plastic trash in the ocean breaks down from the sun's rays and the motion of ocean waves. These small flecks of plastic are harmful to marine organisms and ecosystems. Microplastics can be carried hundreds or thousands of miles away from the source by ocean currents, making it difficult to track and remove them, according to Nasa. As of now, the main source of information about the location of microplastics comes from fisher boat trawlers that use nets to catch plankton and, unintentionally, microplastics.
The new technique relies on data from Nasa's Cyclone Global Navigation Satellite System (CYGNSS), a constellation of eight small satellites that measures wind speeds above Earth's oceans and provides information about the strength of hurricanes. CYGNSS also uses radar to measure ocean roughness, which is affected by several factors, including wind speed and debris floating in the water.
Working backwards, the team at the University of Michigan looked for places where the ocean was smoother than expected given the wind speed, which they thought could indicate the presence of microplastics. They then compared those areas to observations and model predictions of where microplastics congregate in the ocean.
The scientists found that microplastics tended to be present in smoother waters, demonstrating that CYGNSS data can be used as a tool to track ocean microplastic from space. The findings of this research were published online in IEEE Transactions of Geoscience and Remote Sensing earlier this month.
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. June and July, for example, are the peak months for the Great Pacific Garbage Patch, a convergence zone in the North Pacific Ocean where microplastics collect in massive quantities, an official release from the university explains.
This data also showed several brief spikes in microplastic concentration at the mouth of the Yangtze River— which has been long suspected to be a chief source, the release adds. “It’s one thing to suspect a source of microplastic pollution, but quite another to see it happening,” said Chris Ruf, the Frederick Bartman Collegiate Professor of Climate and Space Science at U-M, principal investigator of CYGNSS. “The microplastics data that has been available in the past has been so sparse, just brief snapshots that aren’t repeatable.”
Ruf adds that the information could help organizations that clean up microplastics deploy ships and other resources more efficiently. The researchers, for instance, are already in talks with Dutch cleanup organization The Ocean Cleanup on working together to validate the team’s initial findings, the release explains.