In the middle of the reeds, a piece of red plastic encysts in the earth around the roots of the plants. Upstream of the Tancarville bridge, near the mouth of the Seine (north-west of France), the waste carried by the river has penetrated the thickness of the bank.
This one has a story. The EF56308 label it bears attests to this: the piece of plastic “was thrown away on September 26, 2018” in Rouen, 70 kilometers upstream from the river estuary.
Romain Tramoy is formal: it was he who released him after having duly listed him more than four years ago.
The scientist, a geologist specializing in sediments, has been conducting unprecedented experiments for years to study the crazy life of plastics in the Seine, and to understand not only how many end up there, but also where they come from and how they travel, or not, to ‘at the sea.
Its results are alarming: certainly, there are proportionally few large plastics (more than 5 mm) in the Seine, given the 16 million inhabitants of the basin. But these are tossed about by the currents for sometimes years, without always reaching the English Channel, creating in the estuary “a machine for manufacturing micro-plastics”.
“In a country like France, where it is organized, and where the sewage system works – except for overflows linked to storms for example – we find much less plastic in the rivers than in countries without collection, and with steep gorges, as in Southeast Asia for example”, he told AFP along a bank strewn with waste in Yville-sur-Seine.
But the waste “stays there for years” going “from one bank to the other”. “No waste goes to the sea in a linear way,” says the researcher in paleo-climatology at the University of Paris-Est-Créteil. “They go up and down several times with the tide.”
Plastics, “you find them everywhere, macro, micro, even nano…”
– 100 to 200 tons per year –
The Seine has its source on the plateau of Langres in the Côte d’Or and flows into Le Havre after having watered the feet of the Eiffel Tower and Rouen.
Mr. Tramoy goes to several sites to identify the waste, whether on the bank of Yville, downstream from Rouen, in the loops of the Seine dear to the Impressionists, or along a landscape of Normandy bocage.
There are so-called “accumulation” sites, “real waste collection centers”, and other “dynamic” sites where waste “leaves and arrives every day”.
Sometimes, he “tags” the plastics in fluorescent pink or yellow, to find them perhaps one day elsewhere.
One day in February, on a stony bank, we can make out the different incoming waves. In the “leashes” of branches and driftwood abandoned by the tides, various pieces mingle that Romain Tramoy has rightly labeled in the past.
Detergent bottles, cans, yogurt pots, candy bags, lids, sandals… a Prévert-style inventory of modern consumption.
The experiments of his team between 2017 and 2020 have established that on the Seine, “100 to 200 tonnes of plastic per year arrive at the sea”, much less than his initial assumptions.
– From one bank to another –
The Seine is in fact cleaned, in particular by the Vinci Construction Maritime et Fluvial group, which has been cleaning 66 km of banks for 40 years with cleaning vessels. 26 floating dams are spread over the river as well as the Marne. And associations are picking up on the bank.
Nevertheless, there are still some. To track them, Romain Tramoy has placed “nets” in Rouen at the exit of “storm overflows” where the surplus sewer passes after the rains. The contents are washed, dried, weighed and listed in his laboratory.
“There are about twenty different plastics, and two types of waste: those from the road, such as plastic bottles or cigarette butts from the sewers, and those from the toilets,” he says.
In the net near the Jeanne d’Arc Bridge in Rouen between April 14 and May 23, 2022, 44% of the weight of dried waste is wipes, the scourge of wastewater treatment plants.
– Archaeologist –
Like an Anthropocene archaeologist, the researcher uses recurring products to date flows. One of his favorite markers is “the tube of microlax”, a laxative drug often flushed down the toilet, found in abundance. This allows dating “almost like carbon 14” thanks to the expiry dates of the tube.
At Chapelle Gravenchon, at a place called Petitville near the petrochemical plants, the road winds between flat fields and Norman farms. Reedbeds line the towpaths.
There, the researcher discovered an astonishing area, regularly flooded in winter, where a very dense stock of corks, lighters, cotton swabs mixed with snail shells or small plant waste is concentrated, all in the process of fragmentation. .
“In 2018, we took a square meter of soil in this area, there were 20,000 different pieces of debris weighing a total of 4 kilos, including 10,000 new industrial plastic pellets”. The equivalent of “decades of accumulation”.
An earthworm pushes its way through a plastic cylinder. A head of “Kiki”, a famous doll from the 1980s, sports a green moss hairstyle. Plastic is part of nature.
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#Seine #amazing #journey #plastic #waste
