It’s teeming everywhere – the notorious microplastics even float in the air above the oceans, researchers report. The tiny fragments of plastic waste are thrown up by the surface of the water and can then be spread by the wind for days. As a result, the microplastics can penetrate into remote marine areas particularly easily, threatening the ecosystems there and entering the food chain, say the scientists.
Everyone knows the ugly signature of civilization: garbage is lying around in many places or bobbing on the banks of the waters. Plastic materials are particularly problematic because they no longer disappear completely from nature. They just disintegrate into smaller and smaller pieces until they are referred to as microplastics. This does not reduce the problem – on the contrary: the tiny particles are ingested by many living things, including ourselves, as has been shown in numerous studies. In the body of the organisms, the foreign bodies can then cause damage in various ways and also accumulate in the food chain. The entire potential threat can only be guessed at so far, say experts.
Allele full of plastic crumbs
It is also clear that the problem is enormous, because the environment is teeming with microplastics. According to studies, the tiny particles bob up and down in the oceans, accumulate in the soil and even reach the most remote places: Microplastics have been discovered in the deep sea, in the water and on the ice of the Arctic and in mountain regions. But how does the microplastic get to such remote places that are not directly affected by human pollution? In addition to spreading via ocean currents, transport through the atmosphere also plays a role, studies have already shown. According to this, the microplastic is whirled into the air and distributed on the land by the wind and carried into the water. So far, studies have only shown plastic aerosols in the air over land and in coastal areas and have shown the importance of the entry from the air into the water.
However, the researchers led by senior author Assaf Vardi from the Weizmann Institute of Science in Rehovot are now making it clear that there is also atmospheric propagation from water. The results are based on investigations of samples obtained with the research vessel “Tara” on a research voyage through the North Atlantic. For their investigations, the scientists attached a device for capturing aerosols to the top of the mast of the sailing ship. In addition, they recorded the microplastics in the water of the study regions as well as the ocean currents and wind conditions on the Tara research trip.
Blown up from the surface
As the team reports, the microscopic examinations also showed high amounts of common plastics such as polystyrene, polyethylene and polypropylene in aerosol samples from the remote sea areas during the trip. “We were surprised to find a non-trivial amount over seemingly pristine water,” says Vardi. As the researchers explain, it is apparently microplastic that was blown up and transported from the sea surface by the wind. Comparisons with the microplastics in the water of the sampling regions confirmed this explanation.
According to the researchers’ calculations, the microplastic floating above the ocean has a considerable potential for spreading: it can remain in the air for days and be transported over long distances by the wind. In addition to ocean currents, this is another mechanism for the particles to spread to regions that are far away from civilization, say the scientists.
When traveling through the air, the microplastic could even exacerbate its harmful potential: “As soon as microplastic is in the atmosphere, it dries out and is exposed to UV light as well as atmospheric components with which it interacts chemically,” says first author Miri Trainic from Weizmann Institute of Science. “This means that the particles that fall back into the ocean could be even more harmful or toxic than before for the marine life.” Her colleague Vardi adds: “In addition, some of these plastic particles become breeding grounds for potentially dangerous bacteria, so they can can become a means of transport for the microbes after they go up into the air ”.
As the researchers emphasize, their study has now shown the atmospheric spread of marine microplastics – the significance of the problem should now be examined more closely. “The actual amount of microplastics in the ocean aerosols is almost certainly greater than what our measurements have shown, since our detection methods could not detect particles below a size of a few micrometers,” says Trainic. These particularly light nanoparticles could travel further through the air and thus particularly threaten the ecosystems and food chains, the researchers conclude with concern.
Source: Weizmann Institute of Science, specialist article: Communications Earth and Environment, doi: 10.1038 / s43247-020-00061-y