A new study has produced the first quantitative estimate of nanoplastic concentrations in the ocean, revealing that particles smaller than one micrometer may account for a substantial portion of the long-missing plastic waste in the North Atlantic. The findings mark the first time a nanoplastic detection method has been successfully deployed across open-ocean conditions.
The team collected seawater from 12 locations in the North Atlantic, between the Azores and the European continental shelf. After removing particles larger than one micrometer, they analyzed the remaining material using thermal-desorption proton-transfer-reaction mass spectrometry (TD-PTR-MS) – a method sensitive to volatile organic compounds, adapted here to detect polymer-specific signals in filtered marine particulates.
From these data, the authors extrapolate that between 11 and (roughly) 27 million metric tons of nanoplastics – primarily polyethylene terephthalate, polystyrene, and polyvinyl chloride – are suspended in the North Atlantic Ocean. This far exceeds the estimated mass of larger floating plastic debris in all the world’s oceans combined.
“Until now, nanoplastics have been extremely difficult to detect in seawater,” said Helge Niemann, senior author of the study, in a press release. “But with this approach, we can start to quantify what’s really out there.”
While larger plastic fragments are commonly tracked using net trawls and satellite imaging, nanoplastics – defined as particles between 0.01 and 1 µm – are too small for conventional sampling. The TD-PTR-MS method enabled detection limits as low as 0.01 µg L⁻¹, allowing for ocean-scale estimation. The nanoplastics are thought to originate from the breakdown of macroplastics under UV radiation, as well as from atmospheric fallout, riverine input, and wastewater runoff.
The results provide a plausible solution to the “missing plastic paradox” – the observation that global plastic production vastly exceeds what can be accounted for in surface ocean surveys. “These particles are small enough to be taken up by plankton, bacteria, and even cross biological membranes,” Niemann noted. “Their presence in the ocean has potential implications across the entire food web, including human consumers.”
The team plans to extend its work to other ocean basins and to refine methods for detecting additional polymers, including polyethylene and polypropylene, which may have been masked in the current study. However, the authors stress that mitigation is not feasible at this scale.
“The nanoplastics that are there can never be cleaned up,” Niemann stated. “So an important message from this research is that we should at least prevent the further pollution of our environment with plastics.”
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