Toulouse. We (finally) know the reality of the plastic pollution that passes through the Garonne
Through Anthony Assemat
Published on
Three years ago, in November 2018, the CNRS (National Center for Scientific Research) of Toulouse and the Paul-Sabatier University (via the Molecular Interactions and Chemical and Photochemical Reactivity laboratory as well as the Evolution and Biological Diversity laboratory) launched the PlastiGar project, which aimed to measure and monitor plastic pollution in the Garonne, as well as its impact on biodiversity.
12 sampling sites
A project, funded by the Adour-Garonne Water Agency and the Occitanie Region, which recalls a reality: 80% of plastics found in the oceans, all over the world, Riverside and rivers. Like the Garonne.
In total, 12 sampling sites had been selected in Haute-Garonne to allow scientists to follow the accumulation of pollution in microplastics and the consequences on the contamination of fish.
Pyrenees, Agen and Toulouse metropolis
What exactly did this mission consist of? The CNRS details:
“First of all, the research team set out to characterize the pollution of microplastics in the surface waters of the Garonne and its tributaries, at 14 sites located between the Pyrenees and Agen, via the Toulouse metropolitan area. In 2019 and for four seasons, project scientists deployed nets to filter surface water to measure this pollution. Thanks to a protocol allowing rapid, robust and repeatable treatment of samples collected in the field and containing a large amount of organic matter, scientists isolated a total of 1887 particles of microplastics comprised between 0.7 and 5 mm. These microplastics consisted of polyethylene, polystyrene and polypropylene “.
One in ten fish swallow plastic
And the conclusions are final according to the scientists of the PlastiGar mission: indeed, 2% of invertebrate animals and 10% of fish present in the Garonne have ingested microplastics. “For the species studied, these results led to a mainly direct and accidental ingestion of microplastics composed of the densest polymers when they feed on the bottom of rivers,” the study continues.
The species with the strongest contaminations are invertebrates, with large predators such as dragonfly larvae and crayfish. In fish, they are mainly studs and barbel who ingest these microplastics and who are, in fact, the most contaminated.
A strong phenomenon in the Toulouse metropolitan area
Still according to the conclusions of PlastiGar, “microplastic pollution and the contamination of organisms are omnipresent in the Garonne watershed”, which represents all of the land where all the water that feeds a river flows and infiltrates. water.
A phenomenon accentuated around urbanized areas, such as Toulouse and its agglomeration, “with an increasing concentration when the flow of rivers decreased in summer”.
The Garonne in the average
However, according to scientists, the plastic pollution of the Garonne is no greater than other major French and European rivers. “This level of pollution is nothing extraordinary and is within the range of values observed”, they specify.
But the waters of the Garonne and aquatic biodiversity are not simply threatened by plastic pollution. Other dangers lie in wait… “It is necessary to understand how this pollution interacts with other forms of human pressure on biodiversity, such as habitat fragmentation, climate change and biological invasions”, end of the PlastiGar study .
.
Has this article been useful to you? Note that you can follow Actu Toulouse in the Mon Actu space. In one click, after registration, you will find all the news of your favorite cities and brands.