Fri, Jun 21, 2019 page6

• Team searching for source of plastic in Europe’s rivers

  METICULOUS PROCESS: The Tara Fundation mission aims to understand where microplastic pollution comes from: gutters, industry, our own everyday life

  • AFP, LONDON
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  “Microbeads. A blue one — and a pink one.”

  Armed with a pair of tweezers, Jean-Francois Ghiglione examines the samples fished from London’s River Thames by scientists in search of the source of microplastic pollution.

  “We find completely different things to what we see in the oceans, for example very tiny microbeads from cosmetic products,” said Ghiglione, head bent over a magnifying glass on a ship owned by the Tara Foundation, which is conducting the study.

  From the Pacific to the Arctic Ocean, the scientific vessel has observed the omnipresence of microplastic particles, often no bigger than rice grains, in the seas of the world, but this time Tara decided to throw its nets across 10 of the 15 biggest European rivers, from the Thames to the Tiber, the Rhine to the Seine.

  About 8 million tonnes of plastic end up in the world’s oceans every year.

  Scientists long believed that ocean microplastics came from larger fragments that were broken down over time by currents, bacteria and UV light, but a growing body of research shows how the microscopic particles are already in rivers before they reach the high seas.

  The Tara mission aims to “understand where it comes from: the gutters, industry, our own everyday life,” Tara director Romain Trouble said. “It’s on our doorstep ... the biggest problem with plastic in the sea is on land.”

  Trouble said that he is convinced it is possible to “stop the leakage,” starting with getting rid of “unnecessary packaging,” but to stem the flow more effectively, the exact origin of the pollution must be found.

  For this reason, the Tara team is to cast its nets of fine mesh across 10 rivers at sites of varying salinity, upstream and downstream of big cities.

  A meticulous process in the ship’s onboard laboratory sees each piece of plastic between 1mm and 5mm picked out with tweezers, cut in two and individually placed in thousands of different tubes.

  Half of the tubes stored until November are to be used to identify the types of plastic and trace it back to the original product. The other half would allow the scientists to make a list of all the species inhabiting the “plastisphere,” an artificial habitat used as a “raft” by numerous aquatic microorganisms.

  Downstream other researchers are collecting spoons and straws left strewn on the river bank by the high tide, as biologist Leila Meistertsheim searches for crates of mussels she placed in the water a month earlier.

  “The mussels are open mouths, they swallow everything, so the idea is to use them as bio-indicators,” Meistertsheim said.

  Dissected and frozen in liquid nitrogen, the mussels are then freeze-dried to count the microplastic content in their tissue.

  A third of the molluscs collected at one site were dead. Test results are yet to determine the cause, but the sites where they were placed were undoubtedly polluted.

  “At low tide, there is a carpet of microplastics: toothbrushes, pens, straws, lollipop sticks and many objects unidentifiable with the naked eye,” Meistertsheim said. “The first time I went there, I was scared.”

  There is growing evidence to suggest microplastics can enter the human food chain.

  A WWF report has claimed the average person could swallow up to 5g of plastic a week, equivalent to a credit card.

  However, the danger of these plastics and their chemical additives for living creatures is still unknown.

  So “each piece of plastic will be analyzed by its composition, its pollution, the species living on it and the effect it has on the organisms”, Ghiglione said.

  However, the global conclusions of the 40 scientists and 12 associated laboratories would only be known in a few years, he added.

  Tara’s ship has since made its way to Hamburg, where on the River Elbe, as on the Thames, it is confronted with giant cargo traffic as it conducts its meticulous work.

  “It’s like trying to catch butterflies with a net on Place de la Concorde in Paris during rush hour,” captain Martin Hertau said.
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