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A study published in Nature estimates that the North Atlantic Ocean contains 27 million mt of nanoplastics – particles around 100 times thinner than the width of a human hair, making them the most pervasive form of marine plastic pollution. By contrast, earlier figures, excluding nanoplastics, suggested around three million mt of floating plastic. Researchers collected samples from varying depths and found that concentrations were highest near the surface at 18 mg per sq m. Polyethylene terephthalate (PET) was the most abundant polymer. Given that nanoplastics can penetrate biological membranes more readily than larger fragments, scientists warn of major risks to marine ecosystems and human health, calling for urgent limits on plastic production. (Grist)
Why does this matter? Nanoplastics, which are less than 1,000 nm across and invisible to the eye, can enter the ocean through multiple channels. For example, sunlight, ocean turbulence and temperature fluctuations cause larger plastic items to degrade into smaller particles, eventually reaching the nanoscale. Nanoplastics and larger microplastics – particles less than 5 mm across – resulting from industrial processes, washing synthetic fibres and tyre abrasion, among others, can also flow in from rivers or descend from the air. With an estimated 14 million mt of plastic leaking into the ocean every year, a figure that continues to rise, critical measures are needed now to address the problem.
The study also identified polyvinyl chloride (PVC) and polystyrene (PS) in the collected samples. However, the researchers’ estimate is likely conservative as they were unable to detect two other major classes of plastics known as polyethylene (PE) and polypropylene (PP), although it is highly probable that these also enter the ocean. The team plans further investigations to understand if these particles were obscured by other molecules in the study. They also want to determine if nanoplastics are as prevalent in oceans elsewhere.
Removing the vast amount of nanoplastics already in the ocean is impossible with current technologies. Instead, the focus must be on prevention. Recycling efforts are key, and the global market for recycled ocean plastics is gaining robust momentum. According to a Custom Market Insights report, it is expected to be worth approximately $1.9bn this year and could reach $3.5bn by 2034. Recycling efforts on land are also central to keeping plastic out of the ocean.
Beyond recycling, the world must simply use less plastic. Currently, more than 400 million mt of plastic is produced annually and could triple by 2060. Rio Tinto is playing its part in multiple ways. For example, it has swapped conventional pallet wrap for small parts transport in Western Australia, replacing it with reusable heavy-duty site boxes made from steel. It has also partnered with Canadian ice hockey team Montreal Canadiens to provide spectators with infinitely recyclable aluminium cups at their home arena, the Bell Centre. The move will likely replace 1.5 million single-use plastic cups per year, saving around 24 mt of plastic.
The next meeting to create the legally binding Plastics Treaty will take place from 5 to 14 August in Geneva, Switzerland. This will attempt to finalise the text after negotiations stalled at the previous round of talks in Busan, South Korea in late 2024. Nevertheless, at the close of that meeting, 100 countries warned there could be no treaty without a cap on plastic production, a call that was reiterated at the UN Ocean Conference in June. The world will be watching to see if this can finally be achieved in the coming weeks.