A study led by Utrecht University (the Netherlands) estimates that 27 million tonnes of plastic particles smaller than one micrometre are floating in the North Atlantic.
“This estimate shows that there is more plastic in the form of nanoplastics floating in this part of the ocean than there are larger micro- or macroplastics floating in the Atlantic or even in all the oceans of the world,” said in a statement Helge Niemann, a geochemist and one of the principal authors of the article published in the journal Nature.
To reach that number, the researchers collected seawater samples in November 2020, along a voyage from the Azores to the European continental shelf. Sophie ten Hietbrink, the study’s first author, spent four weeks conducting this sampling, filtering out everything larger than one micrometre.
“By drying and heating the remaining material, we were able to measure the characteristic molecules of different types of plastic in the Utrecht laboratory, using mass spectrometry,” he explains.
The team says this is the first time a “real estimate” of the amount of nanoplastics in an ocean has been achieved. “There are some publications showing that nanoplastics are present in ocean water, but until now no estimate of the quantity has been possible,” Niemann says.
That estimate was possible through extrapolation of the results from the samples obtained at each site. The scientists believe that a large portion of all the plastic produced worldwide thus far is drifting through the oceans as tiny particles.
The presence of nanoplastics in the sea may result from the degradation of larger plastic pieces by the force of waves and solar radiation; they can reach there via rivers contaminated with these materials and can even be transported by air, as suspended particles that fall with rain.
The researchers will continue the work, especially to understand what types of plastic these nanoparticles are made of. “For example, we did not find polyethylene or polypropylene among the nanoplastics,” Niemann reveals, adding that they also intend to determine whether other oceans are affected by the same problem.
“Nanoplastics can penetrate deeply into our bodies, and now that we know they are ubiquitous in the oceans, it is to be expected that they are penetrating the entire ecosystem,” he notes.
