“microplastics are found everywhere in the Atlantic Ocean”

Fabrice Amedeo has set off again for the Everest of the seas. The Angevin skipper took the start of his third Vendée Globe. For several years, he has combined his races with oceanographic campaigns. On November 10, at the start of the largest sailing race around the world, solo, non-stop and without assistance, he took on board a microplastic sensor in partnership with two laboratories from the University of Bordeaux. It's already been five years and a few races, including the 2020 Vendée Globe abandoned in the 40^e roaring, that scientists from the Epoc Unit (Oceanic and Continental Environment and Paleoenvironments) and the Institute of Chemistry and Biology of Membranes and Nano-Objects (CBMN) are associated with the sailor carrying this heavy investment of around 200 000 euros.

The sensor, placed under the keel, is equipped with 300, 100 and 30 micrometer filters which allow different sizes of plastic particles to be trapped and brought up into the cockpit. The route, admittedly truncated in 2020, allowed Bordeaux researchers to carry out a very precise grid of the Atlantic Ocean. Researchers from Epoc, CBMN and Ifremer in Nantes can now take stock of the progress. The 53 samples from 2020, from the size of a hair to that of a mite invisible to the naked eye, were analyzed. They will soon be the subject of a scientific publication.

Cellulose fibers

The first lesson in this long-term collective investigation is that plastic is everywhere, “the finer the plastic particles, the more abundant they are”. This is on average one particle per cubic meter of water (1,000 liters) in a 300 micron (µ) filter, 7/m³ in a 100 to 300 µ filter, 63/m³ in a 30 to 100 µ filter. For Jérôme Cachot, research professor in aquatic ecotoxicology for Epoc, “we hypothesized that we would find more microplastics near the European coasts of the more polluted, more developed Northern Hemisphere, and near the gyres – these large whirlpools. ocean water. In fact, it's more homogeneous. There are relatively few microplastics but they are found everywhere, they are even in the high seas.”

Another surprise was nestled in these large volumes of filtered salt water. Many cellulose fibers have been identified, and also in areas far from the coast. According to researchers, they come from wastewater discharged for example by the textile and paper industries and perhaps even cigarette filters. “These microfibers are colored, this cellulose does not come from wood but comes from human activity, they are not the same polymers,” emphasizes Jérôme Cachot.

“We still have the Pacific and Indian Oceans to sample”

South Seas objective

The two research units, under the supervision of Bordeaux INP, the CNRS and the University of Bordeaux, assiduously follow the journey of their skipper in the service of science. They place their hopes in these new filters that the sailor changes every day and which they themselves brought last October 30 to the technicians of the boat moored in the port of Sables-d'Olonne. “We still have the Pacific and Indian Oceans to sample. The South Seas are of particular interest to us. These are places little known to the scientific community because they are little covered by oceanographic campaigns,” explains the professor. And commercial ships do not go below 35^e south parallel.

Fabrice Amedeo's Imoca also has Argo floats on board, a sensor to measure CO₂salinity, ocean temperature, and another to measure and map marine biodiversity from environmental DNA. “In Antarctica, the water is more homogeneous because it is governed by a circumpolar current. These environmental DNA sensors can make it possible to detect species that we do not know. »