Pollution of the water cycle by plastic: Yann Ourmières, MIO teacher-researcher (OPLC) participates in a scientific mission
On September 21, 2019, Yann Ourmières, professor and researcher at the University of Toulon, boarded the NGO Expedition 7th Continent's schooner for a one-month mission in the Mediterranean.
The mission aims to measure the presence of plastics up to 100 metres deep and in the air above the sea surface. A first!
How is this mission innovative?
What is usually done is microplastic sampling from the surface of the water. The subsurface sampling of nanoplastics is more constraining; the manipulations last nearly 8 hours so we will only be able to do one per day. This is why their presence in environmental matrices, to date, is not documented in any referenced publication. The other originality of the mission lies in the quantification and characterization of nanoplastics. This will require heavier scientific equipment. We are on the verge of opening up to new environmental knowledge.
Why did you choose to explore the Mediterranean?
The mission was initially scheduled to take place in the South Atlantic but, after reflection, we felt it was safer to start with a smaller area to test the new sampling protocols. There is no proven subsurface sampling equipment for nanoplastics, so we had to adapt, in particular, a bongo net traditionally used for plankton.
That said, the Mediterranean is not without interest. The area we have identified, between Sète, Majorca and Sardinia, has similar concentrations of plastics. There is also a frontal area between the north of the Balearic Islands and Sardinia, where bodies of water from the north and south of the western Mediterranean meet. In a few kilometres, a temperature difference of 3 to 4°C can be detected. This has an impact on the dynamics of water masses, which could indirectly impact plastic retention phenomena.
What will be your role in this scientific expedition?
The 7th Continent ship is taking on board a team of CNRS scientists to analyse the accumulation area of plastic waste. Several phenomena will be studied, such as the distribution of micro and nanoplastics in the water column, the way in which micro and nanoplastics interact with organisms and the way in which plastics are integrated into the water cycle. Our team is composed of a chemist - a recognized expert in Europe in the environmental characterization of microplastics, a biologist, CNRS research director specialized in marine microbial ecotoxicology and myself, a physicist oceanographer at the MIO laboratory, specialized in numerical ocean modelling. At the end of this mission, I will be able to make representations of the concentration of nanoplastics and their circulation not only in this area, but also, by extrapolating the results, throughout the Mediterranean. These data can be used as a documentary basis for other researchers. They will also allow us to inform and raise awareness among the general public and local decision-makers about the state of the sea.
Ten years ago, we measured the quantities of plastics to warn about its dangers. Now that we know, it is time to warn about the dangers of nanoplastics. To put figures on hypotheses, explain how they modify ecosystems. Microplastic (1 - 5 mm) is not digested a priori, as it remains mainly in the stomachs of fish. The problem is the bacteria that agglomerate around these microplastics and disperse into the body of the fish we eat. Nanoplastic (1 - 1000 nm) is more insidious. He can't see himself. And when you can't see, you're not afraid. However, the limited scientific production available to us indicates their potential presence in tissues. It is therefore assumed that there may be a direct transfer of water to organisms.
Why should atmospheric samples also be taken?
This is the latest originality of our mission. Atmospheric particulate vacuum cleaners will be installed in the ship's masts to allow us to measure plastic levels in the air and, in this way, model an air/water continuum, a mapping of marine and air currents carrying nanoplastics. This has never been done before.
Also to be read: