WATCH: How sunlight degrades marine plastics

What happens to plastic products that end up in the ocean, left to weather in the sun? A group of researchers set out to look at how this process plays out on a chemical level.

Some of that waste gets concentrated into gyres, or massive systems of rotating ocean currents, said Aron Stubbins, a professor at Northeastern University. The Great Pacific Garbage Patch, for example, is located inside one of them.

In sun-drenched tropical and subtropical gyres, sunlight slowly degrades floating plastics, a process that can both break these products up into smaller pieces and cause them to dissolve, which, he said, releases organic molecules into the water.

To better understand what happens when those plastics dissolve, Stubbins and his colleagues cut up three different types of plastic and separated those pieces into quartz flasks filled with sea water. All of the flasks were placed under “a scientific sunbed” of ultraviolet light, but half of them were wrapped in foil to simulate dark conditions, he said. They also had control samples with no plastics at all.

When the team examined the dissolved organic matter that leached into the light-exposed water over time, they identified hundreds of different chemical products across the three flasks.

What’s still at question is whether and how these compounds are affecting the marine ecosystem. One possibility is that these chemical products could influence the chemistry of the microlayer that exists between the water and the atmosphere, Stubbins said. His team is continuing to look into how marine microbes may be affected, too.

“Because we're dealing with these dissolved molecules, we're thinking more about microbial life, and that microbial life underpins the ecology, the food webs — everything in the ocean,” he added.

This post was produced by Bella Isaacs-Thomas, Megan McGrew, Molly Finnegan and Jackie Hai.

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