Scientists recently estimated, for the first time, that the North Atlantic Ocean contains millions of tons of nanoplastics. To measure it, they used a detection method that picks up the chemical markers, or smell, of trace amounts of burned plastic.
“Imagine you forget a plastic knife in the oven, and you turn it on and it starts to smell,” Dušan Materić, one of the authors of the study, told Mongabay in a video interview. “We are sampling that smell every second. For a knife in the oven, you can smell it in the house. For nanoplastics, it is traces, but our instrument can still detect it.”
Scientists have speculated that the oceans hold significant amounts of nanoplastics, tiny plastic fragments about a thousand times smaller than microplastics. But no one had managed to quantify them until now.
The research team, with scientists from both the Royal Netherlands Institute for Sea Research and the Institute for Marine and Atmospheric Research Utrecht, estimated there’s roughly 27 million metric tons of nanoplastics in just the North Atlantic Ocean.
Since nanoplastics are too small to see, the team detected the miniscule particles via their smell. Or more specifically, the smell of burned plastic.
The testing method starts with filtering seawater samples to remove larger particles. The remaining water is dried and the residue is placed in a device and slowly heated. Clean air is pumped in, and the air that exits, containing the smell of whatever has burned, is measured.
The measuring device can detect the trace chemical signatures of the burning plastic, and since different types of plastic release different compounds, it can identify what the air contains.
Before the study in the North Atlantic Ocean, the researchers used the same testing method to detect nanoplastics in environments including the Dutch Wadden Sea and the snow of the Austrian Alps. But the open ocean had not yet been tested for nanoplastics.
Some of the ocean findings were surprising. In the previous environments, the device picked up polyethylene and polypropylene, two of the most common types of plastic, used in items such as bags and food containers. But in the ocean samples, they were missing, and scientists don’t know why. Materić said it may have something to do with different chemical and physical processes in a marine environment.
“It is a big thing, to now find [nanoplastics] in the ocean environment,” Materić said, adding that until now, nanoplastics have been left out of ocean plastic budget estimates since there had never been any measurements. “We now only know it’s there. And we now need to start printing new pages of scientific discoveries.”
Banner image: Researchers Dušan Materić, left, and Helge Niemann, right, collecting water samples in the North Atlantic Ocean. Image courtesy of NIOZ.
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