Published on : 29/08/2022 – 00:29
Tara’s schooner was on the Gambia River last week. The opportunity to take the very first samples of micro-plastics in an African river. For the foundation, it is also one of the last stages of the mission on marine microbiomes, following leaving Lorient in October 2020.
From our correspondent in Banjul, Milan Berckmans
Aboard the Tara Océan Foundation boat, Jean-François Gighlione, CNRS researcher at the microbial oceanography laboratory in Banyuls-sur-Mer, throws a large net into the water. ” So there, we have the manta net, it’s a net with a size of 330 microns, it’s half a millimeter, approximately “, explains the researcher.
After regarding ten minutes on the surface of the water, the funnel-shaped net rises. At its end, a cylindrical box that should capture micro-plastics for 10,000 liters of water. ” You can see the water inside the collector, there, well, I’ve been sampling all over the world for years, and once you open this collector, you don’t really have any surprises fact, we will inevitably find plastic “says Jean-François Gighlione.
Inside the boat, the microplastics expert takes us to a small laboratory. Here, water samples taken from the Gambia River are scrutinized with a magnifying glass to detect the smallest bit of plastic, which is then isolated for further analysis. These plastics, as well as the water collected, will be used for numerous research projects in France, Europe, the United States, but also in Africa.
First observation for Jean-François Gighlione: while the most polluted waters contain between 100 and 200 micro-plastics per 10,000 liters of water, the waters of the Gambia River contain less. But this waste has not yet been fragmented. ” Here, we found regarding twenty at the estuary, and when we went to Kaur, which is further up the river, we found two. It shows that maybe the fragmentation hasn’t had time to happen yet. »
Also aboard the boat, Famara Jarju represents the Gambian Maritime Authority. For him, the data collected is essential for his country. ” The river is really central for us, we need to better understand what is happening there: the level of salinity, the amount of micro-plastics. This will help Gambians to know what kind of activities they should do in the river. »
With the passage of the Tara Foundation, this is the very first time that data on micro-plastics has been collected from the Gambia River. But as Jean-François Ghiglione explains, the samplings carried out in four places of the river as well as in the estuary are only the beginning, to be able to really interpret these data, it will be necessary to return and carry out other samplings in the future. .
After two years around South America and Africa, Tara’s mission on marine microbiomes will end in October, with a return to her home port of Lorient. In the meantime, the crew will carry out its last scientific stage in Dakar, with another study of micro-plastics – in particular – of the Senegal River.
