The life cycle of plastic is becoming more and more detailed. Thursday, January 5, 2023, scientists National Center for Scientific Research (CNRS) He presented a life cycle diagram in Toulouse plastics and microplastics On the surface of the earth. Global evolution takes into account the movement of particles between land, air and sea. This study involved an entire French team, including scientists from the Toulouse Earth Sciences and Environmental Laboratory (GET/OMP) and the Functional Ecology and Environmental Laboratory.
Jeroen Sonke is the coordinator and scientist of the project CNRS. in an interview Independent Opinionhe explains the background of these first results published in the journal Microplastics and Nanoplastics.
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How did you become interested in the life cycle of microplastics?
We’ve been hearing a lot about microplastics on the surface of the ocean for a decade. And today there are many experts who study this issue. We have even started research on the presence of microplastics in the atmosphere. Each is specialized in their skills. Once we wanted to make an integral juice of the life cycle of plastic particles found on the Earth’s surface, in the atmosphere and in the oceans. Thus, we synthesized the observations we made in the last ten to fifteen years.
What are these first published results?
We looked at the question: how much plastic and microplastic is in the ocean? We always hear what’s floating on the surface, and there are efforts to clean the surface, but how many are inside? How much plastic is in marine sediments? Because plastics break down and fall to the bottom of the water. One of the novelties of the research is that we find that there are 100 times more plastic and microplastic in the water than on the surface. And it puts things into perspective.
Do you have numbers to communicate?
Proof by the numbers: one million tons have been found on the surface, 82 million tons in the deep ocean, and about 110 million tons in sediments. It’s interesting because now we know the amount of plastics produced since the 1950s, 8,000 million tons. There are 200 million in the marine environment, which is 3% of what has been produced so far.
You created a diagram, how does it translate?
Research covers issues revolving around the oceans, but also at ground level as well as atmospheric deposition. And we created a mathematical model from all these numbers that we put together. With this model, we are able to make predictions, in particular we can calculate the timescales on which plastics released into the Earth’s environment break down, are transported to the ocean, and on which timescales they reach the atmosphere to be deposited elsewhere.
What exactly do we find in the oceans?
What we see is that in the coastal sediments we find a lot of macro-plastics, bottles of all sizes. And in deep sea sediments, up to 10,000 km deep, we find microplastics instead. After that, it breaks down in coastal areas, but not to forget all the products that use microplastics, such as cosmetics. Already, a quarter of plastic pollution in the terrestrial environment comes from microplastics. It is then carried to the ocean along with the rains and rivers.
So how does this plastic life cycle work?
We see that even if we stop polluting today or in the very near future, the plastic cycle is not over, it continues. Plastic will degrade, break down and be recycled for millennia. It also teaches us that it is good to clean the surface of the oceans, but we will have to attack the terrestrial environment. Because the pollution first starts there and then goes to the oceans. The ground level needs to be cleared.
What’s next for research?
Solutions are available: improve recycling, reduce production and use. But this is on the right track. There are some places where it will be easier than others. But in terms of research, we are still on the atmospheric side. We are currently mapping the real-world microplastics in the air around the planet. This first mathematical model remains quite rudimentary. I would like to adapt it to simulate different types of plastic more realistically. We also know that plastics are increasingly breaking down into nano-plastics, which is interesting to us. But we need a lot of observations.
More information can be found on the CNRS website.
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