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Half a billion metric tons of plastic waste is unaccounted for

Although the billions of tons of plastic products produced over the last half-century (called by many the “Plastic Age”) have drastically changed the way we live for the better, the plastic waste that found its way into the environment is posing major challenges for nature. 

According to a new study led by Kyushu University, about 25.3 million metric tons of plastic may have entered our oceans and almost two-thirds of this amount cannot be properly monitored. Even more alarmingly, this could be only the tip of the plastic-waste iceberg, with another 540 million metric tons of mismanaged plastic waste still trapped on land (the equivalent of approximately 10 percent of all the plastic manufactured so far).

While scientists have been investigating the oceans’ surfaces and beaches to determine how much plastic waste has reached the oceans, massive amounts of ocean plastics are most probably well below the surface, hidden by the reach of scientific observation if using common sampling equipment.

“To assess the amount and whereabouts of plastic waste in the Earth’s oceans, we have to consider the whole process from their birth to burial, starting with emission from rivers into the ocean and continuing with their transportation and fragmentation into pieces,” said study lead author Atsuhiko Isobe, a professor of Physical Oceanography at Kyushu University.

Together with his research team, Professor Isobe created models that simulate these processes, by using satellite-data to investigate the movements of the plastic particles, as well as a massive amount of data about global plastic-debris emissions going back to 1961.

Their results suggest that large plastics and microplastics floating on the ocean surface each account for only about three percent of all ocean plastics. While a similar amount of microplastics was estimated to be on the beaches, 23 percent of the ocean plastic waste was larger plastic litter spread on the shores.

According to the simulations, the remaining two-thirds of ocean plastic may be in locations that make it impossible to monitor, such as the seafloor. However, compared to ocean plastics, the amount of mismanaged plastic waste on land which could find its way into ecosystems and oceans in the future could be twenty times larger. Being indecomposable in nature, this half a billion metric tons of plastic may likely outlive us and many other species.

Further investigations are needed to locate these plastics and build efficient methods of disposing them. “That’s going to be a Herculean task. Few advancements have been made so far in the field of ‘terrestrial plastics’ due to the lack of observation methods,” concluded Professor Isobe.

The study is published in the journal Science of the Total Environment.

By Andrei Ionescu, Staff Writer

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