Ocean cleaning study shows how plastic goes to Pacific Garbage Patch

A plastic item floats in the Great Pacific Garbage Patch.The cleaning of the ocean

• Millions of tons of plastic accumulate each year in the oceans, but only a small fraction of it is found on the surface.
• For years, scientists have thought that the "missing" plastic was rapidly degrading into tiny fragments after entering the ocean, then that it fell to the bottom of the ocean.
• A new study by The Ocean Cleanup, a nonprofit organization founded by Boyan Slat, 25, challenges this theory.
• The study revealed that plastics were undergoing a long journey to areas like the Great Pacific Garbage Patch, a vortex filled with garbage that is more than twice the size of Texas. Along the way, the plastic is either pushed back to the ground or sinks under the surface of the water.

• Visit the Business Insider home page for more stories.

About 8.8 million tons of plastic accumulate in the oceans each year, but it is thought that only 270,000 tons float on the surface of the ocean.

For years, most scientists have thought that "missing" plastic degrades quickly after entering the ocean, breaking down into microplastics – tiny fragments less than 5 millimeters long. These small pieces then fall to the bottom of the sea, estimated many researchers.

But this theory contradicts the observations made by researchers at The Ocean Cleanup, a non-profit organization that aims to rid the oceans of plastic. The organization was founded in 2013 by entrepreneur Boyan Slat, who was only 19 years old at the time. Slat is now 25 years old and is getting closer to his goal of cleaning up the Great Pacific Garbage Patch, an ocean vortex filled with garbage that is more than twice the size of Texas.

Read more: The huge plastic cleaning device invented by a 25-year-old man may well be recovering waste in the Great Pacific Garbage Patch. Take a look at his difficult journey.

On Thursday, The Ocean Cleanup published a study that offers an alternative explanation for why some plastic objects stay on the surface of the water while others disappear. The team discovered that rather than rapidly dissolving in microplastics, plastic objects were regularly pushed back to the ground or disappeared beneath the surface of the water.

"It's a rather upsetting point of view," Slat told Business Insider. "I think we were able to answer, or at least mention, the biggest gap in knowledge in the field of plastic pollution."

"We do not really find plastic bags or straws"

Plastic fragments found in the big Pacific dump.The cleaning of the ocean

In recent years, Ocean Cleanup researchers have found that a specific type of plastic accumulates in the landfill.

"Much of it is weathered and broken down, and some look really old," Business Insider Lawrence Lebreton, the senior author of the study, told Business Insider. "We do not really find plastic bags or straws, but we find very thick and hard plastic fragments."

The researchers found that the majority of the objects recovered in the dump in 2015 were from the 2000s. Some were much older.

This suggested that plastic objects did not disintegrate very quickly.

"It's really shocking to see pieces of plastic still floating in the 1970s," Slat said. "Just a few weeks ago, we recovered a crate that literally dates back to 1970 in Japan."

The researchers concluded that instead of falling apart, plastic objects embark on a long journey, sometimes for decades, before accumulating in large offshore areas.

The journey of plastic across the ocean

Circular cycles of plastic pollution.The cleaning of the ocean

A small part of the plastic in the ocean comes from illegal dumps, spills at sea or production facilities that release plastic debris into nearby water courses. But most of it comes from rubbish on the mainland.

Plastic waste entering the ocean sometimes accumulates along the coast, where there is no human to pick up waste. The Cocos Islands, Australia, is an example, an isolated area with few inhabitants and the highest density of plastic debris reported in the world (about 260 tonnes). On these banks, a large amount of plastic is washed away by the tide, then brought back to the same place.

This cycle ends when the plastic breaks down or spreads offshore.

The researchers found that less than 1% of the plastic that enters the ocean from the coast ends up in a gyre like the Great Pacific Garbage Patch.

When a plastic object moves into the ocean, organisms like algae or barnacles attach to it and begin to get bored – a process called "fouling". The object then sinks under the surface of the water, towards the deepest parts of the ocean.

Algae and barnacles need sunlight to survive, and this becomes rare as they sink deeper into their plastic house. Eventually, organisms can die and fall from the plastic object, allowing it to rise to the surface of the water.

Ocean Cleanup found a crate in the Great Pacific Garbage Patch dating back to the 1970s.The cleaning of the ocean

Lebreton said that thick plastic pieces often resist the weight of organisms, while thin pieces tend to lose their buoyancy. This explains why there are not many fragile straws or plastic bags in the waste pile, he said. Researchers have discovered that thin pieces of plastic can rise to the surface in deep water, but that in shallower waters they are more likely to land at the bottom of the ocean and remain there.

Clean up the big Pacific dump

Eventually, the plastic that swirls in the swirls off is degraded, but it may take some time. The researchers found that most of the plastic objects being disintegrated into microplastics were manufactured in the 1990s or earlier. When a plastic object gets degraded, the resulting microplastics tend to rain like ash toward the bottom of the ocean.

Lebreton said the waste in the Great Pacific Garbage Patch could take decades, if not centuries, to disintegrate without any intervention.

"If you stop putting plastic in the ocean or in the natural environment in general, you will still have to deal with the legacy of plastic waste," he said. "In this sense, we can truly say that the worst is yet to come."

Boyan Slat.Getty

Slat said the new study "confirms the strategy" of The Ocean Cleanup, as solving the problem of plastic pollution requires both prevention (for example, on-shore recycling efforts) and cleanup. plastic already in the water.

Slat's solution is a U-shaped floating network that captures the plastic in its crease like a giant arm. The aircraft moves slower than the ocean current through an underwater parachute that serves as an anchor. While winds and natural waves push the plastic toward the center of the U-shaped system, debris is captured by a screen that extends beneath the surface of the ocean. The collected garbage can then be towed to the coast by a boat.

If successful, the Ocean Cleanup project indicates that its device could halve the size of the garbage dump over five years.

"For me, it's not really a question of whether it's going to work, it's when it's going to work," Slat said. "I do not think we have a choice given the scale of the problem."