It is thought that there are greater than 14 million lots of plastic on the sea flooring
According to an estimate based on new research, there are likely at least 14 million tons of plastic parts less than 5mm wide at the bottom of the world’s oceans.
The analysis of ocean sediments from a depth of up to 3 km suggests that there could be more than 30 times as much plastic at the bottom of the world’s ocean as there is floating on the surface.
The Australian science agency CSIRO collected and analyzed cores from the ocean floor, which were taken from six remote locations about 300 km off the south coast of the country in the Great Australian Bight.
The researchers examined 51 samples and found that every gram of sediment, after excluding water weight, contained an average of 1.26 pieces of microplastic.
Microplastics are 5mm or less in diameter and are mostly the result of larger plastic objects breaking up into smaller and smaller pieces.
Containing the flood of plastic entering the world’s waterways and ocean has emerged as a major international challenge.
Dr. Denise Hardesty, a senior scientist at CSIRO and co-author of the research published in Frontiers in Marine Science, told the Guardian that finding microplastics in such a remote location and at such depth “indicates the ubiquity of plastics.” no matter where you are in the world ”.
“That means it’s in the entire water column. It gives us reason to think about the world we live in and the impact of our consumer habits on a place that is considered untouched, ”she said.
“We have to make sure that the big blue isn’t a big garbage dump. This is further evidence that we need to stop this at the source. “
The cores were drilled between 288 km and 349 km offshore at depths between 1,655 and 3,016 m in March and April 2017.
Hardesty said it was not possible to know how old the pieces of plastic were or what items they once belonged to.
But she said the shape of the pieces under a microscope suggested they were once consumer goods.
For the study, the researchers extrapolated the amount of plastic found in their core samples and from research by other organizations to conclude that up to 14.4 million tons of microplastics were on the ocean floor worldwide.
While this seems like a large number, Hardesty said it was small compared to the amount of plastic likely to end up in the ocean each year.
In September, a study estimated that between 19 and 23 million tons of plastic ended up in both rivers and oceans in 2016.
An earlier study in Science magazine estimated that around 8.5 million tons of plastic end up in the oceans each year.
Another study estimated that 250,000 tons of plastic float on the ocean’s surface.
In the latest work, the authors find that their estimate of the weight of microplastics on the ocean floor is between 34 and 57 times the weight on the surface.
Hardesty said the estimates were flawed, but were based on the best information available.
“It is useful to give people a sense of the scope and scope that we are talking about,” she said.
However, she said the amount of plastic on the ocean floor is relatively small compared to any plastic released, suggesting that deep-sea sediments are not currently a major resting place for plastics.
She said she believes the vast majority of plastics actually accumulated on the coasts. “Much more is caught on land than at sea,” she said.
Dr. Julia Reisser, marine biologist at the Oceans Institute at the University of Western Australia, has been researching plastic pollution for 15 years.
“The marine scientists were really obsessed with figuring out where the plastic was,” said Reisser, who was not involved in the study.
It took several scientific methods to understand the potential impact of plastics on ocean wildlife. Larger plastic can entangle wildlife, while microplastics and even smaller pieces can be consumed by a number of species from plankton to whales.
She said the new study was an important contribution to the global effort and hoped the deep-sea data from Australia could be combined with other efforts around the world to give future studies a more accurate picture.
Reisser has also set up a new organization to study new plastics using seaweed as a base material.
“I think the ultimate fate [of marine plastics] is the deep sea, but we are far from being in balance, ”she said.
“If we could travel a thousand years into the future, this plastic would have slowly splintered and been removed from our coast.”
Executives from more than 70 countries signed a voluntary commitment to reverse biodiversity loss in September, which included the goal of preventing plastic from entering the ocean by 2050.
Major countries that did not sign the pledge included the United States, Brazil, China, Russia, India, and Australia.