Atmospheric micro- and nanoplastics pollute the ocean

It is estimated that by 2040 the level of plastic pollution could reach 80 million metric tons per year. Plastic particles have now been detected in virtually all spheres of the environment, for example in bodies of water, soil and air. Via ocean currents and rivers, the tiny plastic particles can even reach the depths of the Arctic, Antarctica or the oceans. A new global study has now shown that wind, too, can transport these particles over great distances – and much faster than water: in the atmosphere, they can travel from their point of origin to the farthest corners. of the planet in no time. days. In the journal Nature Reviews Earth and Environment, an international team of researchers – including experts from the Alfred Wegener Institute, the Institute for Advanced Sustainability Studies in Potsdam and the GEOMAR Helmholtz Center for Ocean Research in Kiel – describes how microplastic finds its way through the atmosphere and how it is then transported.

Today, between 0.013 and 25 million metric tons of micro- and nanoplastics per year are transported thousands of kilometers by sea air, snow, spray and fog, crossing countries, continents and oceans. This estimate was made by an international team of 33 researchers, including experts from the Alfred Wegener Institute, the Helmholtz Center for Polar and Marine Research (AWI), the Potsdam Institute for Advanced Sustainability Studies ( IASS) and the GEOMAR Helmholtz Center for Ocean Research. Research in Kiel.

“Air is a much more dynamic medium than water,” says co-author Dr. Melanie Bergmann of AWI. “As a result, micro- and nanoplastics can penetrate the most remote and still largely untouched regions of our planet much faster.” Once there, the particles could affect the surface climate and the health of local ecosystems. For example, when these darker particles settle on snow and ice, they affect ice-albedo feedback, reducing their ability to reflect sunlight and promoting melting. Likewise, darker patches of seawater absorb more solar energy, warming the ocean more. And in the atmosphere, microplastic particles can serve as condensation nuclei for water vapor, producing effects on cloud formation and, in the long run, on the climate.

How do plastic particles enter the atmosphere?

First by human activities. Particles produced by road traffic tires and brakes or by exhaust gases from industrial processes rise into the atmosphere where they are transported by the winds. However, according to the overall study, there is also evidence to suggest that a significant number of these particles are transported by the marine environment. Early analyzes indicate that microplastics from the coastal zone are also ending up in the ocean through eroded beach sand. The combination of spray, wind and waves forms air bubbles in the water containing microplastics. When the bubbles burst, the particles end up in the atmosphere. As such, transport to remote and even polar regions could be due to the combination of atmospheric and maritime transport.

Therefore, it is important to understand the interactions between the atmosphere and the ocean, in order to determine what sizes of particles are transported and in what quantities. The atmosphere primarily transports small microplastic particles, making it a much faster transport route that can lead to significant deposition in a wide range of ecosystems. As Melanie Bergmann explains: “We need to integrate micro- and nanoplastics into our air pollution measurements, ideally on an international scale as part of global networks.” To that end, first author Deonie Allen and Bergmann began collecting samples of microplastics from air, seawater, and ice during a Polarstern expedition to the Arctic last year. last.

Joining forces to understand the microplastic cycle

Understanding and characterizing the cycles of microplastics between the ocean and the atmosphere will require joint efforts. In this regard, in the study, the team of researchers led by first authors Deonie Allen and Steve Allen of the University of Strathclyde, Glasgow, outlines a comprehensive strategy to create a transparent and intercomparable database on the flow of micro- and nanoplastic between the ocean and the atmosphere. “There are so many aspects of the emissions, transport and effects of microplastics in the atmosphere that we still don’t fully understand,” says co-author Professor Tim Butler of the IASS. “This publication reveals the gaps in our knowledge and presents a roadmap for the future.”

Two dedicated working groups of the Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP) prepared the study. According to study co-author and GESAMP member Professor Sylvia Sander of GEOMAR: “The study clearly shows that a full understanding of the ocean and the effects of human influences on it cannot be achieved. only by networking researchers and their data. The great challenges of our time are global. Therefore, we must seek answers to pressing questions with as comprehensive and international expertise as possible. This cannot can only be done by working together. GESAMP is a conglomeration of eleven organizations belonging to the United Nations. Its objective is to arrive at a multidisciplinary and scientific understanding of the marine environment. To date, the network has already collaborated with more of 500 experts from countries around the world on a series of questions.

Micro- and nanoplastics in the air are also important for human health. In a recently published British study, microplastics were detected in the lungs of 11 out of 13 living humans. “This is yet another reason why we need to incorporate plastic into air quality monitoring programs,” Bergmann points out. In order to reduce plastic pollution of the environment, the production of new plastic should also be successively reduced on the basis of an international treaty, as Bergmann and other experts recently demanded in a letter to the newspaper. Science.

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