Tons of Ocean Plastic Debris has Disappeared

Researchers say that plastic islands in oceans have disappeared.

Millions of tons of plastic items end up in oceans each day. For over a decade, scientists have assumed that most of the plastic ends up as "plastic islands" that float on oceanic surface. The Great Pacific Garbage Patch is one such example of plastic debris accumulating on the surface of the ocean.

However, researchers at the University of Western Australia's Oceans Institute now said that the plastic in the ocean is disappearing into an unknown sink. Researchers have found a lower concentration of plastic waste in the water samples than other study models had predicted.

According to the team, rise of plastic production led to an increase in plastic debris in the ocean. The amount of litter going into the water bodies initially kept pace with the production of plastic. However, in the mid-1980s, the level of plastic debris in the ocean levelled-off, despite the continuous disposal of these polymers, according to a news release.

Plastic breaks down into smaller bits due to sunlight and oceanic currents. Researchers in the current study used fine mesh to catch these ultrafine particles. But, surprisingly, the plastic load in the water samples was less than predicted. The team said that plastic bits might have entered marine creatures' bodies, The Verge reported.

"There is potential," said Carlos Duarte, an oceanographer at the University of Western Australia and co-author of the study, according to The Verge, "for this plastic to enter the global ocean food web."

The samples for the study came from Spanish Circumnavigation Expedition Malaspina 2010, which was a nine-month expedition to study the effect of climate change on the world's oceans. Researchers looked at samples obtained from 3,070 ocean surface samples collected from 141 sites around the world. They found that around 88 percent of the water samples had plastic particles of varying sizes.

According to the team, the water samples had low concentration of plastic fragments that were smaller than one millimetre in diameter. Also, the concentration of plastic particles was less than expected.

The study is published in the journal Proceedings of the National Academy of Sciences (PNAS).

Microbes dwell on tiny bits of marine plastic. A recent study had found that silica-forming algae might be weighing down these plastic bits and causing them to sink.