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Researchers use satellites to track ocean microplastics from space

Environmentalists have been raising awareness about the problems caused by microplastics in the oceans — tiny pieces of plastic which can harm marine animals and damage ecosystems. But it’s hard to say how widespread the issue is, as it’s difficult to track all of the plastic in the ocean.

Now, researchers are using a NASA satellite to track how plastics move throughout the ocean. The Cyclone Global Navigation Satellite System (CYGNSS) is a set of eight small satellites that was, as the name suggests, designed to track hurricanes and to understand the formation of storms. But researchers at the University of Michigan realized they could use data from the satellite system to both track microplastics on a global scale and to zoom into specific areas to get high-resolution data.

“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 senior author Chris Ruf.

Illustration of one of the eight CYGNSS satellites in orbit above a hurricane.
Illustration of one of the eight CYGNSS satellites in orbit above a hurricane. NASA

The satellites were already measuring the roughness of the ocean surface as part of their hurricane monitoring job. Ruf and his colleagues realized they could take this existing data and identify areas that looked smoother than they should, given the wind speed. This correlates well with the presence of microplastic, letting them track this issue globally.

“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. “So I got the idea of doing the whole thing backward, using changes in responsiveness to predict the presence of stuff in the water.”

The results show that the concentration of microplastics changes with the seasons, and converges in places like the infamous Great Pacific Garbage Patch. They also found a high concentration of microplastics at the mouth of the Yangtze River, the longest river in Asia. This area had previously been thought to be a primary source of microplastics, but this new evidence shows the problem in action.

“It’s one thing to suspect a source of microplastic pollution, but quite another to see it happening,” Ruf said. “The microplastics data that has been available in the past has been so sparse, just brief snapshots that aren’t repeatable.”

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