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Plastic is a huge problem in the oceans, but engineers and research groups are working on how to deal with it. Hank describes some of the leading proposed solutions.

Hosted by: Hank Green
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Hank: Since it was invented over a century ago, plastic has become an established part of human life. It’s built into our houses, our vehicles, our food containers, our clothing, and unfortunately, our oceans.

It’s a really big, bad problem -- but there are some solutions that might help. An estimated 4-12 million metric tons of plastic washes into the oceans every year, and this debris causes lots of problems. Marine animals get physically tangled in larger waste, and hundreds of species ingest smaller bits of plastic, mistaking it for food, or accidentally swallowing it, which can kill them. Plus, some plastics contain harmful substances like bisphenol-A, PCBs, phthalates, and flame retardants that can leach into the ecosystem and move up the food chain.

It can take hundreds of years for plastic to fully degrade, and because microplastic is about the same size as a lot of the plants and animals living in the water column, it’s extremely difficult to filter out. Ocean currents send a lot of this garbage to one of five patches, or gyres, in the Pacific, Atlantic, and Indian Oceans. The Great Pacific Garbage Patch, for example, is twice the size of Texas, and lives somewhere between California and Hawaii.

Researchers estimate that combined, these five patches contain anywhere from 500,000 to 200 million tons of plastic. So one option would be to start cleaning up the ocean by targeting these monstrosities. Like the Ocean Cleanup project, developed by Boyan Slat when he was a teenager. After many research expeditions, Slat came up with a giant V-shaped prototype. Each arm of the V is a floating boom with a trailing, submerged screen designed to passively collect debris using ocean currents. As water moves through these long, floating barriers, lighter-than-water plastic gets caught in front of the barriers. Meanwhile, the screens under the surface catch smaller submerged plastics, while sea life can safely swim beneath the screens. From there, plastics get funneled toward the center of the collector, where a central platform extracts, stores, and eventually recycles it back on land.

The Ocean Cleanup project hopes to deploy a smaller-scale model off the coast of Japan later this year, to test things like the barrier’s durability and efficiency in real-life conditions. But some oceanographers worry how Slat’s system will affect sea life, and how unmanned stations will withstand brutal ocean storms.

Others are trying to find the best places to set up plastic removers. Researchers from Imperial College London found that it could be more effective to recapture debris closer to shore, before currents can carry it to the middle of the ocean, where it’s harder to collect. They ran a series of computer simulations using a model of 29 hypothetical floating trash collectors, or sinks, similar to the ones proposed by Slat. Their model took into account things like ocean currents, where the trash was coming from, and the distribution of phytoplankton and other marine life.

When they ran the simulations with the sinks in different test locations, they found that placing the sinks in certain offshore areas -- mostly off the coasts of China and Indonesia -- would remove about 31 percent of all ocean plastic by 2025. The sinks would catch plastics as they entered the ocean, as well as debris swept along by currents. Meanwhile, models of sinks deployed around the Pacific garbage patch only cut trash by about 17 percent. Plus, the simulations showed that sinks closer to the shore -- as opposed to the open ocean -- had less of an impact on marine life.

But even if these methods work, and make a significant dent in sea trash, new plastic is always coming in. Australia’s national science agency recently completed a massive three-year study of ocean trash and estimated the world doubles its plastic production every decade. That’s probably why, at least for now, many experts agree the best solution is to just stop all that plastic from getting into the water in the first place.

About 80% of ocean trash comes from land, and most of it consists of water bottles and plastic packaging. And there are ways to reduce that trash: things like being less dependent on plastics, making sure waste is disposed of properly, and putting up catch nets around storm drains. No matter how we do it, cleaning up the oceans will be hard. But by preventing as much plastic as possible from getting into the oceans in the first place, and by collecting as much as we can of what does get in, we might be able to make some progress.

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