The Arctic polluted by microplastics
The study published in Science Advances was carried out after Tara's expeditions around the world and more particularly in the Arctic. It turns out that despite the low population density in this region of the world, the Greenland and Barents Seas (the northern part of the North Atlantic) accumulate large quantities of plastic debris, brought by ocean currents. This is a real disaster for this still virgin and remote ecosystem.
In previous studies, Andrés Cózar's research team had shown that each of the five oceanic gyres acts as a huge convergence zone for floating plastic debris. A more recent study also indicated that densely populated semi-enclosed seas, such as the Mediterranean, could also be areas of significant accumulation of plastic debris. The Arctic Ocean, which is far from inhabited areas, has not been affected by this accumulation of microplastics until now.
A 5 month sampling period
During the Tara Oceans expedition, the schooner had been sampling around the Arctic basin and sampling microplastics for five months to produce a world map of the plastic pollution floating. "Plastic concentrations in Arctic waters were low, as we expected, but we discovered an area north of the Greenland and Barents Seas with relatively high levels", comments Andrès Cózar. "There is a continuous transport of floating waste from the North Atlantic, and the Greenland and Barents Seas are a dead end for these plastics, carried to the pole by ocean currents and forced to remain on the surface."
The foundation estimates that several hundred tonnes of floating plastic debris are trapped in the surface waters of this area. It consists of nearly 300 billion pieces, mostly rice-sized fragments, and perhaps even more. Since the debris is not only in the surface water, but also in the deep ocean.
Plastic pollution from the North Atlantic
With the increase in maritime activity in this remote area, plastic is now available from local sources. But most of the plastic found in the Arctic Ocean comes from the large-scale transport of waste from the densely populated North Atlantic coasts generated by ocean currents.
This plastic transfer towards the poles is linked to the meridional overturning circulation in the Atlantic, a "conveyor belt" known until now to redistribute heat from the warmest latitudes towards the poles.
To reach this conclusion, the team used data from more than 17,000 drifting buoys, floating in the ocean surface and tracked by satellite. "What is really worrying is that we can follow this plastic to the approaches to Greenland and into the Barents Sea directly from the coasts of north-western Europe, the UK and the east coast of the US. It is our plastic waste that ends up there", says van Sebille of the Grantham Institute at Imperial College London.
Plastic pollution is invading the planet
Humanity has only been using plastic for a few decades, but pollution generated in marine environments is already a global problem - clear proof that humans have the capacity to alter our planet. "The sea has no boundaries," stresses Maria Luiza Pedrotti of the CNRS, " plastic pollution generated in one place can contaminate other isolated areas, with devastating effects on a pristine ecosystem such as the Arctic. This area forms a cul-de-sac, a dead end where currents leave debris on the surface. We may be witnessing the formation of another global wastebasket, without fully understanding the risks to local flora and fauna."
"The results of this study underline the importance of minimizing and better managing plastic waste at its source by industry, households, communities and states, because once it reaches the ocean, its destination and impacts become uncontrollable" says Romain Troublé, director of the Tara Expeditions Foundation.
A team composed of 12 institutions from 8 countries
The study team, led by Professor Andrés Cózar of the University of Cádiz in Spain, is composed of 12 institutions from 8 countries : tara Expeditions Foundation (France), King Abdullah University of Science and Technology (Saudi Arabia), CNRS (France), Imperial College London (United Kingdom), Lake Basin Action Network (Japan), University of the Balearic Islands, the Higher Council for Scientific Research (CSIC), Spain), the Sorbonne University, the University of Aarhus (Denmark), the University of Utrecht (Netherlands), Harvard University (USA), the Basque Science Foundation IKERBASQUE (Spain) and the Expert Technology Centre for Marine and Food Innovation AZTI (Spain).
