Enormous floating barrier will corral ocean trash | Science News for Students

Enormous floating barrier will corral ocean trash

Critics question whether it will do much good
Oct 8, 2018 — 6:45 am EST
a computer generated image of what the Ocean Cleanup system will look like floating in the North Pacific

This computer rendering shows what the 600-meter-long (2,000-foot) Ocean Cleanup system will look like floating in the North Pacific. Currents will push on the boom to form a u-shape. The system is designed to trap bits of plastic that boats can collect later.

The Ocean Cleanup

Watch out, ocean trash! On September 8, a project to scoop plastic debris from the ocean launched its first phase from Alameda, Calif. Called  Ocean Cleanup, its creators claim it that by 2040 can remove 90 percent of the plastic in the Great Pacific Garbage Patch. If true, that would be a lot of plastic.

When researchers visited the that so-called garbage patch back in 2015, they estimated that it covered some 1.6 million square kilometers (620,000 square miles). That’s an area twice the size of Texas.

Boyan Slat first proposed Ocean Cleanup’s system in a 2012 TED talk. At the time, he was just 18 years old. The Dutch-born inventor’s system consists of many floating tubes. Known as booms, they form a long, snaking line. This barrier will collect floating plastic trash so people can come by and retrieve it. People have donated more than $30 million to fund the project, based in Delft, the Netherlands.

Not everyone, however, thinks it’s a great idea. Some researchers worry the project could harm ocean life. There’s also the issue of the targets’ size. Ocean Cleanup is designed to capture pieces of plastic ranging from a few millimeters in diameter to tens of meters across, such as fishing nets. In fact, bits smaller than half a centimeter across — so-called microplastics — make up the majority of ocean plastic. The project has not been designed to catch such small bits.

Critics also worry the project will take attention and money away dealing with the root cause of this pollution: too much plastic waste in the first place.

plastic debris from the ocean waters
Much ocean plastic is in bits too tiny for Ocean Cleanup to catch. But when team members went to the great Pacific garbage patch in 2015, they found that more than 90 percent of the plastic garbage, by mass, is in pieces larger than 5 centimeters (2 inches). Here’s some of that debris.
The Ocean Cleanup

Ready for launch

Laurent Lebreton is Ocean Cleanup’s lead oceanographer. He led a study of the Great Pacific Garbage Patch. This is an infamous collection of trash in the Pacific Ocean. The trash collects in a vast ocean swirl known as the North Pacific gyre.

A new study estimates that this patch includes about 1.8 trillion pieces of debris. Buoyant plastics, such as polyethylene (Pah-lee-ETH-eh-leen) and polypropylene (Pah-lee PRO-puh-leen), dominate. Most are pieces smaller than half a centimeter (0.2 inch) across. But by mass, most of the bits of plastic —90 percent — are pieces 5 centimeters or bigger.

Lebreton’s team shared its findings March 22 in Scientific Reports.

It’s those larger pieces that Ocean Cleanup has been designed to snag. Its line of floating booms 600 meters (almost 2,000 feet) long will drift on the water, driven by winds, waves and ocean currents. Currents will naturally push the line of booms into a u-shape. And that will corral plastic debris as it travels. Beneath the surface, the booms drag a 3-meter-long (10-foot) skirt. This net will let only the tiniest bits of plastic escape.

Solar-powered lights, satellite antennas and other equipment show boats where the booms are. These features should help prevent boats from colliding with the booms. They’ll also help project scientists track where the floating system is. Periodically, boats will go out to the booms and ferry home much of the plastic it’s holding for recycling.

A line of test booms, called “System 001,” launched September 8. Ocean Cleanup has also tested parts of the system in the North Sea and off the California coast. After two weeks of testing off California, System 001 will head to the North Pacific gyre, Lebreton says. If all goes well, it should arrive within five weeks of the launch date. “We’re hoping to bring the first plastic back before the end of the year,” he says.

Ocean Cleanup plans to eventually have about 60 such systems. With the full fleet deployed, the group says, it should be able to remove 50 percent of the plastic in the patch within five years. By 2040, it hopes to have eliminated 90 percent — by weight.  

a picture of System 001 in the ocean near Alameda California
Ocean Cleanup teams put together System 001 in Alameda, Calif., a few weeks before the launch.
The Ocean Cleanup

New ecosystems

Plastic is bad for the environment. But no one knows whether the boom-and-cleanup system itself might pose any harm.

Ocean Cleanup hired an outside group to investigate how the system might affect marine life. Its report, published in July, found no reasons for serious concern. But it did note one small concern: Sea turtles might be drawn to the system and then eat the trash.

There are many other issues the report didn’t cover, says Kim Martini. She’s a physical oceanographer at Sea-Bird Scientific. This Seattle-based company makes tools to measure ocean properties. Martini wrote about Ocean Cleanup in January 2017 for the oceanography blog Deep Sea News. In her piece, she listed some worries. For example, the booms’ sweeping net could gather marine hitchhikers, from algae to barnacles and other kinds of critters. They could add drag to the system and change how well it performs, she says.

Also unknown, she says, is whether herding the plastic will cause new, tiny ecosystems to form amidst the trash. This could possibly attract even more wildlife to the area that the system might then scoop up by accident.

Another big issue, Martini says, is that there’s no evidence yet that the system can actually collect much plastic. The latest California trial will be the first real test of how well the system may works.

Marcus Eriksen also doubts the system will collect as much plastic as Ocean Cleanup’s team claims. He’s an environmental scientist at 5 Gyres Institute. This is a nonprofit in Los Angeles, Calif. Eriksen worked with Lebreton worked on a 2014 study of ocean plastic. It estimated that there are 5 trillion bits of ocean plastic worldwide. But many of these bits quickly leave the surface, they reported in the journal PLOS ONE.

A lot of the debris washes ashore, gets shredded or sinks, Eriksen says. So many of the small particles would end up below the project’s 3-meter-deep skirt. Meanwhile, new particles are always entering the ocean. That’s why 5 Gyres and other conservation groups are focused on prevention, not cleanup. Persuading people to use less plastic in the first place is the best way to reduce ocean trash, Eriksen says.

Every effort helps

The Ocean Cleanup team says its project is meant to work together with such prevention measures. For now, it’s worth trying to remove whatever is already floating near the surface, they argue.

Whatever the result of their new tests, some groups are applauding Ocean Cleanup for raising awareness of the ocean’s plastic trash problem.

“I love how passionate people are about the Ocean Cleanup project,” says Adam Lindquist. He’s director of the Healthy Harbor Initiative in Baltimore, Md. His group installed a pair of water wheels at two river mouths in his city’s Inner Harbor area. Anchored to the ocean floor, the floating are have booms and skirts much like those on the Ocean Cleanup system. The two wheels are nicknamed Mr. Trash Wheel and Professor Trash Wheel. In four and a half years, they’ve scooped up some 900 tons of debris — ranging from contact lenses to mattresses. This was all trash kept out of the ocean.

“Any tech that’s removing plastics from the ocean is a good thing,” Lindquist says. But the bigger value in such programs will be their “getting people to take the problem more seriously, so that we can move toward real solutions.” In other words, stopping plastic from entering the ocean in the first place.

Power Words

(for more about Power Words, click here)

algae     Single-celled organisms, once considered plants (they aren’t). As aquatic organisms, they grow in water. Like green plants, they depend on sunlight to make their food.

antenna     (plural: antennae) In biology: Either of a pair of long, thin sensory appendages on the heads of insects, crustaceans and some other arthropods. (in physics) Devices for picking up (receiving) electromagnetic energy.

blog     Short for web log, these internet posts can take the form of news reports, topical discussions, opinionated rants, diaries or photo galleries.

conservation     The act of preserving or protecting something. The focus of this work can range from art objects to endangered species and other aspects of the natural environment.

current     A fluid — such as of water or air — that moves in a recognizable direction.

debris     Scattered fragments, typically of trash or of something that has been destroyed. Space debris, for instance, includes the wreckage of defunct satellites and spacecraft.

diameter     The length of a straight line that runs through the center of a circle or spherical object, starting at the edge on one side and ending at the edge on the far side.

drag     A slowing force exerted by air or other fluid surrounding a moving object.

ecosystem     A group of interacting living organisms — including microorganisms, plants and animals — and their physical environment within a particular climate. Examples include tropical reefs, rainforests, alpine meadows and polar tundra. The term can also be applied to elements that make up some an artificial environment, such as a company, classroom or the internet.

environment     The sum of all of the things that exist around some organism or the process and the condition those things create. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature and humidity (or even the placement of components in some electronics system or product).

gyre     (as in the ocean) A ringlike system of ocean currents that rotate clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere. Many of the biggest, most persistent gyres have become collection sites for floating long-lived trash, especially plastic.

marine     Having to do with the ocean world or environment.

mass     A number that shows how much an object resists speeding up and slowing down — basically a measure of how much matter that object is made from.

microplastic     A small piece of plastic, 5 millimeters (0.2 inch) or smaller in size. Microplastics may have been produced at that small size, or their size may be the result of the breakdown of water bottles, plastic bags or other things that started out larger.

oceanography     (adj. oceanographic ) The branch of science that deals with the physical and biological properties and phenomena of the oceans. People who work in this field are known as oceanographers.

Pacific     The largest of the world’s five oceans. It separates Asia and Australia to the west from North and South America to the east.

particle     A minute amount of something.

physical     (adj.) A term for things that exist in the real world, as opposed to in memories or the imagination. It can also refer to properties of materials that are due to their size and non-chemical interactions (such as when one block slams with force into another).

plastic     Any of a series of materials that are easily deformable; or synthetic materials that have been made from polymers (long strings of some building-block molecule) that tend to be lightweight, inexpensive and resistant to degradation.

polyethylene     A plastic made from chemicals that have been refined (produced from) crude oil and/or natural gas. The most common plastic in the world, it is flexible and tough. It also can resist radiation.

polypropylene     The second most common plastic in the world. It is tough and durable. Polypropylene is used in packaging, clothing and furniture (such as plastic chairs).

satellite     A moon orbiting a planet or a vehicle or other manufactured object that orbits some celestial body in space.

sea     An ocean (or region that is part of an ocean). Unlike lakes and streams, seawater — or ocean water — is salty.

Texas     The second largest state in the United States, located along the southern border with Mexico. It is about 1,270 kilometers (790 miles) long and covers an area of 696,000 square kilometers (268,581 square miles).

trillion     A number representing a million million — or 1,000,000,000,000 — of something.

waste     Any materials that are left over from biological or other systems that have no value, so they can be disposed of as trash or recycled for some new use.

Citation

Journal: L. Lebreton et al. Evidence that the Great Pacific Garbage Patch is rapidly accumulating plasticScientific Reports. Published online March 22, 2018. doi:10.1038/s41598-018-22939-w.

M. Eriksen et al. Plastic pollution in the world’s oceans: More than 5 trillion plastic pieces weighing over 250,000 tons afloat at seaPLOS ONE. Published online December 10, 2014. doi:10.1371/journal.pone.0111913.

Further Reading