Name: Why 99% of ocean plastic pollution is "missing"
Uploaded: 2021-05-16T14:21:31.000Z
Duration: 9 min
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

Between Hawaii and California,  --in an area about twice the size of Texas--

転換語

For decades, tons of our plastic debris has accumulated there because of swirling ocean

It looks like a cloudy soup: and that's because the plastic objects are spaced far

apart, and they range in size from large debris to microscopic.There are at least 4 other

garbage patches like this in the world, And after scientists discovered them, starting

They thought that this might be where a lot of the plastic ended up, out there floating

But recently, scientists brought large nets to the Great Pacific Garbage Patch, and took

a closer look at the objects they pulled out.

They found water bottles And hard hats And bottle caps 

And laundry baskets And using what they found, they were able

to calculate how much debris was in all of the garbage patches. 

There were about a few hundred thousand tons of plastics at the surface of the ocean, which

But a few hundred thousand metric tons of plastic is only about 1% of the estimated

8 million tonnes of plastic scientists believe is emitted into the ocean every year.

So scientists have been left investigating a mystery: Where does the rest of the ocean's

  This is clue number 1 in the case of the missing

plastic: a sea floor sediment sample  It was taken from the bottom of the Santa

Barbara Basin, off the coast of California. 

It represents a measure of time, from 1870 at its deepest layer of sediment, up until

But this period, from 1945 to 2009, is where the study authors were focused on. 

In these layers, the study authors found plastic fibers and fragments that were 1 millimeter

They found more and more plastic particles as the years went on, doubling every 15 years. 

That rate is nearly identical to the rate of global plastic production. 

Ss soon as you see a layer of microplastic you pass the 1950's and that's the legacy

This is Laurent Lebreton—he works at the Ocean Cleanup, and led the study of the objects

The sea sediment study looked at microplastics—particles smaller than 5 millimeters.

These either come from clothing fibers, or they are the result of larger plastics breaking

We've found these tiny particles floating throughout the ocean, And even in the guts

of the ocean's tiniest creatures, like plankton.

But the sediment study shows that  some of our plastic is likely hiding, buried

But here's another clue: This is a plastic bag, captured 2,500 meters below the surface

It's one of over 2,100 photographs taken with this deep sea camera. 

Part of the work that we're doing is to look at the impact of climate change in the Arctic.

We use towed camera surveys to look at the impact on large animals like starfish and

And while I was doing these surveys, I saw that more and more plastic debris was on the

Melanie Bergmann's research shows that large plastic objects don't just float on the

surface or degrade into microplastic — some of them sink without breaking down. 

One study found that about 50% of plastic in landfills is more dense than seawater,

which means these objects could sink on their own.

But even those other 50 percent may actually travel to the sea floor with time, because

what we see is that the debris which is floating on the ocean surface becomes colonized with

biota over time… barnacles, mussels, all sorts of different organisms… then it becomes

heavier and heavier and at certain at a certain point and then starts to sink.

Bergmann's research is difficult to replicate throughout the ocean, because of the challenge

But it suggests that some of that missing plastic might be sitting on the seafloor,

Another clue complicates the mystery, though: this plastic crate, from Taiwan.

It's one of the objects excavated during that harvest in the Great Pacific Garbage

And what struck researchers was its production date: 1971. 

When they looked at the production dates of other objects, they saw a trend: a lot of

This was a new lead: because if the majority of plastic pollution degraded into microplastic

or fell to the ocean floor, then what you'd see in garbage patches would be new plastic.

And that changed the story...the plastic that is accumulated at the surface of the ocean

The plastic we find in subtropical oceans may actually be there for decades, if not

It turns out the new plastic is far closer than the open ocean or the bottom of the deep

Lebreton's research found that plastic objects on coastlines have more recent production

This clue led scientists to think a lot of debris actually stays close to shorelines

around the world—hidden in plain sight. 

Some of that will end up in the middle of the ocean and garbage patch, but actually

a lot of it stays fairly near shore and hop from beach to beach to beach. 

Erik Van Sebille is an oceanographer, and is building an ocean model that predicts where

The completed model will be finished in 2022, but in the meantime he and his team publish

We use simulations of the ocean currents and they're a bit like weather models for the

So they tell us how the currents are moving stuff around.

And then we move that plastic with the ocean flow.

At the same time the plastic and fragment, it can degrade, organisms start growing on

it that weighs down the plastic so that it slowly starts to sink into the deeper ocean.

So in that way, we're doing like this gigantic simulation of all of the ocean, of all the

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Why 99% of ocean plastic pollution is "missing"

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