What does it take to reduce the levels of microplastics in the oceans?

At today’s rate, in 2040 microplastics in the oceans can increase by 2.6 times

We need very ambitious reduction targets and radical industrial change to reduce microplastic pollution in the oceans. But even by substantially cutting plastic production and reducing the amount in the sea, plastic polymer fragments smaller than 5 millimeters will continue to float on the surface for many decades.

This does not mean that intervention is useless. “Plastic is now everywhere in the environment and the ocean is no exception. While our findings show that microplastics will be present in the oceans beyond the turn of the century, stabilizing their levels is the first step towards elimination,” explains Zhenna Azimrayat Andrews, first author of a study published in Environmental Research Letters that provides a useful perspective for the negotiations on the global plastic treaty that are ongoing under the auspices of the UN. Last year, a study calculated that at today’s rate of production and pollution, in 2040 microplastics in the oceans can increase by 2.6 times.

The study that will show the real extent of microplastic pollution

How can we at least stabilize microplastics in the oceans?

The team analyzed 8 plastic reduction scenarios, calculating their actual impact on ocean microplastic levels up to 2100. The bad news is that no ambitious trajectory can eliminate this type of pollution relatively quickly. Why?

The models developed and tested in this study take into account the interaction between microplastics and marine biology, in particular, the tendency of fragments to form agglomerations with phytoplankton or with excrement produced by zooplankton. The amount of microplastics and their properties tend to make these agglomerations float, slowing their descent into the lower parts of the water column. The more they remain on the surface, the more the plastic fragments are likely to enter the trophic chains, that is, to be ingested by fish and other marine life, in turn, consumed by man.

Taking this dynamic into account, the researchers have established that to stabilize the levels of microplastics in the oceans it is necessary to reduce plastic pollution by 5% per year globally. But even the most ambitious trajectories take several decades to shoot them down. For example, by reducing pollution by 20% per year, even after 2100 microplastics would remain on the surface of the oceans. And, in any case, they would accumulate on the seabed and in the ocean depths, where their impact is still largely unknown.

“There can never be a complete removal of microplastics from all depths of the ocean, we just have to live with it now,” Azimrayat Andrews points out. “But the current global production of plastic pollution is so large that even an annual reduction of 1% in pollution would make a big difference overall”.

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