Assessment of microplastic pollution in Atlantic Ocean based on Science and Sailing collaboration

The quasi-ubiquitous presence of microplastics has become an alarming concern due to the real and potential dangers that they pose to the environment, in particular in our oceans. Relatively well documented for the coastal environment, data from offshore Oceans remains fragmented. In every case, the fraction below 100 microns is rarely taken into account, especially due to analytical difficulties. For the first time, teams from Ifremer and University of Bordeaux have analysed the microplastic pollution thank to sampling done by the skipper during the Vendée Globe 2020 race. Its Imoca boat was equipped with a specific microplastic sampler that filtered seawater during 24 hours each day of racing on three sieves with mesh sizes of 300 µm, 100 µm and 30 µm. The interlaboratory comparison demonstrated the efficiency of analytical process developed for each size range. Furthermore, this study has revealed the microplastic omnipresence in the Atlantic Ocean with a mean concentration of 71 microplastics per m3, but also quantified the increase of particle concentration and increase of polymers diversity as the size decreased on. In parallel, a specific focus was realized on microfibers characterization and quantification present in the three size ranges. Microfibers represent a large part of anthropogenic pollution, between 78 % to 94 % of particles for 100 µm and 300 µm sieves, respectively. Interestingly, the majority of microfibers have been identified as cellulosic derivate, raising the issue of their origin and resistance as well as their potential toxicity. It appears crucial to address the smallest particle fractions and the microfibers. Finally, this study paves the way for a long term monitoring of Oceanic microplastic pollution through a strong collaboration between scientific and sailing world with the Vendée Globe 2024 as second step.