On 21 September 2019, Yann Ourmières, a teacher-researcher at the University of Toulon, boarded the schooner of the NGO Expedition 7th Continent for a month-long mission in the Mediterranean.
The aim of the mission is to measure the presence of plastics at depths of up to 100 metres and in the air above the surface of the sea. It's a first!
How is this mission innovative?
What is usually done is to take samples of microplastics from the surface of the water. Subsurface sampling of nanoplastics is more restrictive; the manipulations last nearly 8 hours, so we can only do one per day. This is why their presence in environmental matrices has not yet been documented in any referenced publication. The other original aspect of the mission is the quantification and characterisation of nanoplastics. This will require heavier scientific equipment. We are on the threshold of a new environmental knowledge.
Why did you choose to explore the Mediterranean?
The mission was initially planned to take place in the South Atlantic but, after some thought, we decided it would be 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 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 zone between the north of the Balearic Islands and Sardinia, where water masses from the north and south of the western Mediterranean meet. In just a few kilometres, there can be a temperature difference of 3 to 4°C. This has an impact on the dynamics of the water masses, which could themselves have an indirect impact on plastic retention phenomena.
What will your role be on this scientific expedition?
The boat 7th Continent is taking a team of CNRS scientists on board to analyse the area where plastic waste accumulates. 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 role of plastic in the water cycle. Our team is made up of a chemist - a recognised expert in Europe in the environmental characterisation of microplastics, a biologist and CNRS research director specialising in marine microbial ecotoxicology and myself, a physical oceanographer at the MIO laboratory, specialising 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. This data will serve as a documentary basis for other researchers. It will also enable us to inform and raise awareness among the general public and local decision-makers about the state of the sea.
Ten years ago, we were measuring the quantities of plastics to warn of their dangers. Now that we know, it's time to warn about the dangers of nanoplastics. We need to put numbers to hypotheses and explain how they are changing ecosystems. Microplastics (1 - 5 mm) are not digested a priori, as they remain mainly in the stomachs of fish. The problem lies with the bacteria that agglomerate around these microplastics, which are then dispersed in the bodies of the fish we eat. Nanoplastics (1 - 1000 nm) are more insidious. It cannot be seen. And when you can't see it, you don't fear it. However, the limited scientific evidence available indicates their potential presence in tissues. It is therefore assumed that they can be transferred directly from water into organisms.
Why are atmospheric samples also taken?
This is the last original aspect of our mission. Atmospheric particle aspirators will be installed in the ship's masts to enable us to measure the levels of plastics in the air and thus model an air/water continuum, a map of marine and air currents carrying nanoplastics. This has never been done before.
Read also:
Article UTLN : http://www.univ-tln.fr/Un-oceanographe-de-l-UTLN-traque-dechets-plastiqu…
FB : https://www.facebook.com/Expedition7eContinent/
Website : http://www.septiemecontinent.com/