Microplastics are present in the marine atmosphere even in remote parts of the world. These tiny particles come from land sources but are also re-emitted into the atmosphere from the sea, a seemingly new finding made by researchers at the University of Oldenburg.
The scientists analysed air samples taken from various sites along the Norwegian coast all the way up to the Arctic region. The results have now been published in the scientific journal Nature Communications.
“With our study, we present data on the mass load of different types of plastic in the marine atmosphere for the first time,” said Isabel Goßmann, a doctoral candidate at the University of Oldenburg’s Institute for Chemistry and Biology of the Marine Environment (ICBM). The research team collected the samples during an expedition with the Research Vessel Heincke in 2021. The northernmost destination was Bear Island, the most southerly island of the Svalbard archipelago which lies halfway between the mainland and the archipelago’s largest island, Spitsbergen. The team used two different devices to collect air samples. The devices actively pumped in air and were mounted on the bow of the research vessel at a height of twelve metres.
Different types of plastic found
The scientists analysed the air samples using pyrolysis-gas chromatography-mass spectrometry. They identified and quantified the different types of plastics in the atmosphere through thermal degradation and selective analysis. They then performed model calculations and reconstructed the sources and distribution paths of the particles, each of which is just a few thousandths of a millimetre in size.
The analysis revealed the omnipresence of polyester particles. Polyethylene terephthalate particles were also detected in all samples, which presumably entered the atmosphere in the form of textile fibres. Other plastic present included polypropylene polycarbonate and polystyrene. Another major source of microplastics confirmed by the study is tyre wear particles, the tiny debris abraded from tires during driving and especially braking. The researchers measured concentrations of up to 37.5 nanograms of microplastics per cubic metre of air. “These pollutants are ubiquitous. We find them even in remote polar regions,” Goßmann stressed.
A rarely studied phenomenon
Until now, little was known about microplastics pollution levels including tyre wear particles in the marine atmosphere. “There are only a handful of studies on the concentration of these pollutants in the air,” said team leader Scholz-Böttcher. “Our model calculations indicate that the microplastics in the marine atmosphere come from direct sources on the land as well as from the sea,” she added. The team posits that plastic particles floating near the sea surface enter the atmosphere via sea spray and bursting air bubbles produced during stormy weather, for example.
Ships are also a source
Microplastics find their way into seawater via rivers, but also through the atmosphere – particles are washed out of the atmosphere by rain, for example. Another potential source is ship traffic: in an earlier study, a team led by Scholz-Böttcher demonstrated that in the open North Sea, the paint and coatings used on ships is the main source of microplastics.
This latest study also found that air samples contained chemicals such as polyurethanes and epoxy resins typically used in paints and coatings for ships.