It is 35 times more plastic than it is thought to be floating on the surface, the study suggests.
The researchers say the work is the first global estimate of microplastics – pieces of plastic that have been cut into smaller pieces by elements that are smaller than 5 millimeters (0.19 inches) – along the coast.
Using a robotic submarine, the team collected sea sediment samples from six locations up to 3000 m (9,800 ft) deep in the Great Australian Stirling Byte, 380 kilometers (236 miles) off the coast of South Australia.
Analysis of the 51 samples taken revealed that there was an average of 1.26 microplastic fragments per gram of silt. Researchers say it’s 25 times more microplastics than previous cold-sea studies.
“The deep sea is also vulnerable to the problem of plastic pollution,” said Justin Barrett of CSIRO Oceans and Atmosphere, who led the study.
“Plastic pollution that ends up in the ocean spoils and breaks down, ending up as microplastics,” he said. “The results show that microplastics are actually sinking to the bottom of the ocean.”
Dr Research Nis Hardsty, principal research scientist and co-author of the study, said he was “surprised by observing high microplastic loads at such a remote location.”
Research shows that plastics can accumulate on the shore by being submerged by a water column or by transporting microplastics deep underwater into an underwater valley.
“Our research has shown that the ocean is a sink for ocean microplastics.” “By recognizing where and how much microplastic there is, we get a better picture of the extent of the problem.”
The main samples were taken in March and April 2017 in the ths depth range of 1,655 m (5,400 ft) to 3,062 m (10,000 ft). The researchers then scaled back their data from the coast of Australia to obtain a global estimate of the weight of microplastics in the deep sea silt and reached an estimate of 14.4 million metric tons. – The estimates they make are accurate because the location was remote and away from urban population centers.
While their findings show a large amount of microplastics on the coast, researchers say it is a fraction of the total amount of plastic that is dumped into the world’s oceans each year.
And researchers say most of the plastic dumped into the ocean ends up on the beach instead of the sea surface or floor.
The results show that it is more urgent than ever to find effective solutions to prevent plastic pollution and reduce the use of plastics in general before they reach the oceans.
“This will also help in reporting waste management strategies and creating opportunities for behavioral change and preventing plastics and other waste from entering our environment,” he said. “Government, industry and the community need to work together so that we can significantly reduce the amount of waste in our beaches and seas.”
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