A mask thrown in the street.

(Illustration) -

Maureen McLean / Shutterstock / SIPA

  • Disposable masks are regularly discarded in nature.

    However, this new source of pollution takes more than 400 years to degrade in the environment.

  • Toulouse students decided to see what role aquatic organisms could play in its degradation.

  • They launched an experiment in the three rivers of the Pink City and in the laboratory.

Just a year ago, finding an abandoned surgical mask in a street in the Ville Rose would have been an unusual discovery.

Today, it is commonplace to see it in the gutters, which will eventually end up in the waters of the Canal du Midi or those of the Garonne.

Enough to push Toulouse students to study how the environment can act on the decomposition of these disposable objects.

Composed of layers of polypropylene, a widely used and far from biodegradable polymer, they are believed to take almost 400 years to completely disappear after being casually thrown into the environment.

A very polluting vestige of this health crisis that organisms living in aquatic environments could help, despite themselves, to degrade more quickly.

Indispensable to fight against # COVID19, # surgical #


masks risk #polluting our #soils and # rivers.

A group of students @ENSAT_INP @ UT3PaulSabatier decided to study the fate of these masks thrown into #nature: https://t.co/Vq6aOrvq6z pic.twitter.com/Ua0rbvfUb8

- Functional Ecology & Environment Laboratory (@FuncEcolEnv) November 20, 2020

"We saw that many surgical masks flourished on the sidewalks, we then asked ourselves the question of the interaction with the living, through our experience we want to know which macro or microorganisms can colonize them and how they interact with" , explains Virgile, one of the five students of the Codemasc project, carried out as part of their master's degree in “Ecosystems and Anthropization”, in partnership with the Laboratory for Functional Ecology and Environment in Toulouse.

Mini-snails on the attack

To carry out their experiment, they therefore immersed around forty masks in the waters of the Canal du Midi, the Hers and the Touch on October 20 for a period of six weeks.

But also in the laboratory, where they simulated the natural environment, while being able to control the degradation mechanisms over the same period.

They want to see if tiny aquatic snails, called physes, play a role in the loss of mass of the mask and its rate of degradation.

The latter nibble on the biofilm, a kind of layers of algae and micro-organism, which forms on the surface of the masks.

In the laboratory, adding nitrogen also increases the nutrient in the biofilm.

A snail nibbling at the biofilm covering a mask.

- Codemasc

“We did our readings and realized that there was more organic matter than we thought, microorganisms that were interested in it.

In laboratory aquariums, physes have an impact.

In nature, other parameters can also be taken into account, such as currents or UV.

With the naked eye for the moment we don't see a big difference, ”explains Aurélie, one of the other students in the project who will share her results on her blog.

At a time when there is a lot of talk about the plastic continent, through their work, the team also seeks to raise awareness about microplastics pollution, much closer to us and which could certainly be avoided.

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  • Experience

  • Recycling

  • Science

  • Toulouse

  • Coronavirus

  • Pollution

  • Planet

  • Biodiversity