Washington (AFP)

On the tiny Inaccessible Island, aptly named in the middle of the South Atlantic, most plastic bottles washed ashore were probably dumped by Chinese merchant ships, a study released on Monday concludes.

This work is further evidence that the islands of floating plastic waste in the midst of the oceans, which are raising awareness among the general public, come less from bottles and other single-use items thrown into the wild and streams. by consumers, and more by the fishing and shipping industries, which release tons of plastic at sea.

The authors of the article in the American journal PNAS collected and compared thousands of wastes during visits to the small island in 1984, in 2009 and 2018. The island is located on the gyre of the South Atlantic, c that is, a whirlwind of currents on an oceanic scale that concentrates in the middle what are called "waste vortices".

While initially most of the bottles on Inaccessible Island had inscriptions showing that they came from South America, carried by currents from the shores to 3,000 kilometers to the west, in 2018 three-quarters came from Asia, especially from China.

Many of these PET bottles were crushed with the screw cap as is done on the boats to save space, says lead author Peter Ryan of Cape Town University in South Africa. The dates of manufacture were recent, 90% in the two previous years, excluding that they traveled from the Asian coast, hence the trip takes rather three to five years.

And as the number of Asian fishing vessels has been stable since the 1990s, while the number of Asian and mainly Chinese merchant ships has increased significantly in the Atlantic, the researchers conclude that all these bottles come from merchant ships, which get rid of them instead of bringing them back as waste on land.

"There is no other explanation: they come from boats and not land," says Peter Ryan to AFP. "Part of the merchant fleet seems to be responsible, and apparently it is the Asian fleet".

- Fishing waste -

It is therefore necessary to distinguish two types of marine pollution.

On the one hand, beaches around major urban centers. The plastic found there comes from the ribs: bottles, bags and plastic packaging. But these light objects flow easily and are less carried away by the currents.

Farther into the oceans, waste vortices contain fragments of objects of uncertain origin, as well as articles used by the merchant navy and fishing vessels: not only the bottles consumed on board, but also nets, ropes, buoys, crates, helmets, floats ....

"This is a cause of poorly known pollution," says Peter Ryan.

The large Pacific waste vortex is half made up of fishing nets (in bulk), estimates a team that published a study last year in Scientific Reports.

Oceanographer Laurent Lebreton, one of the authors of this study, says that the figure often quoted that 80% of plastic pollution comes from land does not make the difference between coasts and high seas.

He says he found huge piles of fishermen's nets in the Pacific called "fish aggregating devices" to attract fish.

"Often they do not recover and lose them, we found several tons," said Laurent Lebreton, of the organization The Ocean Cleanup, to AFP.

"Everyone is talking about saving the oceans by stopping plastic bags, straws and single-use packaging - that's important, but when we go out into the ocean, it's not necessarily what we find, "says the researcher.

© 2019 AFP