CLEAN­ING THE OCEAN

Pro­to­type of process to fil­ter the plas­tic in the Pa­cific Ocean is be­ing tested

Vocable (All English) - - Découverte - ASH­LEY COATES

Bot­tles, bags, tyres, syn­thetic fi­bres… Each year mil­lions of tons of plas­tic are poured into the ocean. Not biodegrad­able to any help­ful ex­tent, of­ten in­vis­i­ble, this rub­bish is threat­en­ing the marine fauna and pro­gres­sively en­ter­ing the food chain. To deal with this pol­lu­tion, a young Dutch­man is test­ing his in­ven­tion in the Pa­cific ocean.

In

1998, Charles Moore, an oceanog­ra­pher, was sail­ing across the North Pa­cific when he made an unwelcome discovery. “As I gazed from the deck at the sur­face of what ought to have been a pris­tine ocean, I was con­fronted, as far as the eye could see, with the sight of plas­tic,” Moore wrote in Nat­u­ral His­tory mag­a­zine. “It seemed un­be­liev­able but I never found a clear spot. In the week it took to cross the sub­trop­i­cal high, no mat­ter what time of day I looked, plas­tic de­bris was float­ing ev­ery­where – bot­tles, bot­tle caps, wrap­pers, frag­ments.” What he stum­bled on be­came known as the Great Pa­cific Garbage Patch or “Pa­cific trash vor­tex”. It is thought to be any­where be­tween the size of Texas (700,000 square kilo­me­ters) to sev­eral times that size.

2. Most of the plas­tic waste that ends up in the oceans is thought to be­come part of these “garbage patches” of rub­bish. De­scribed as a “tick­ing time bomb” by marine sci­en­tists, the Great Pa­cific Garbage Patch is be­lieved to have grown by five times in the past 10 years and will be­come a greater risk to life as the plas­tic de­grades fur­ther. It’s a prob­lem that caught the imag­i­na­tion of a then 16-year- old school­boy from the Nether­lands, Boyan Slat. “I had to do a high-school science project that year and I de­cided to re­ally ded­i­cate my­self to this is­sue. Ev­ery­body told me it would be im­pos­si­ble to clean up, the main prob­lem be­ing that the plas­tic is ex­tremely dis­persed... over a wide area.”

FIL­TER­ING OUT PLAS­TICS

3. The key idea that makes Slat’s con­cept dif­fer­ent to other schemes is the prin­ci­ple of “let­ting the sea do the work” by hav­ing ocean cur­rents run into V-shaped screens that fil­ter out small plas­tics. When the sys­tem is fully op­er­a­tional, the plas­tics

can then be loaded onto small ves­sels and taken back to land for re­cy­cling. To­day the Ocean Clean Up Foun­da­tion em­ploys more than 70 peo­ple and has around $ 30m (€ 25m) in fund­ing. But the task con­fronting Slat and his team will re­quire a great deal more than this.

4. Although it’s hard to gain ac­cu­rate data, to­day’s es­ti­mates sug­gest roughly five tril­lion pieces of plas­tic are now float­ing in our oceans. Seven mil­lion tons are dumped into the sea each year. The Ellen MacArthur Foun­da­tion es­ti­mates that the vol­ume of plas­tic waste in our oceans will out­weigh the to­tal mass of fish in the sea by 2050.

5. Hav­ing tested a pro­to­type model of its sys­tem in the North Sea last year, The Ocean Cleanup an­nounced in May that it plans to con­duct a trial in the Pa­cific later this year, and start a full cleanup op­er­a­tion there next spring. “We’re start­ing with the North Pa­cific gyre sim­ply be­cause it is the largest ac­cu­mu­la­tion of plas­tic. A third of all ocean plas­tic can be found in that area. We’ll gather data and im­prove the sys­tem con­tin­u­ously”.

6. I ask Slat what has trou­bled him the most about the sit­u­a­tion fac­ing our oceans. “Def­i­nitely the degra­da­tion,” he says. “Plas­tic doesn’t re­ally go away by it­self.” “The con­cen­tra­tion of plas­tic is rapidly in­creas­ing in the gyres. Even if you were to close off the tap, and no more plas­tic en­tered the ocean, that plas­tic would stay there, prob­a­bly for hun­dreds of years”.

7. Not only a threat to sea life, the degra­da­tion of ocean plas­tics leads to the re­lease of chem­i­cals that are known to be harm­ful to hu­mans when they en­ter the food chain. Sig­nif­i­cant de­bris can cause dam­age to ship­ping, foul up tourist sites and en­cour­age in­va­sive species. Much of our older marine waste is now break­ing down into more toxic and hard-to-re­move sub­stances, and reach­ing parts of the sea pre­vi­ously thought to be rel­a­tively pris­tine.

Seven mil­lion tons of plas­tic are dumped into the sea each year.

8. Boyan Slat has other plans as to how the foun­da­tion can help solve this prob­lem. “We might work on ways to pre­vent plas­tic get­ting into the ocean in the first place. We pub­lished a study in Na­ture back in June, show­ing that 86 per cent of the plas­tic is com­ing from Asia, and com­ing from a rel­a­tively small num­ber of rivers in those ar­eas. So, in the fu­ture, we could do some­thing there within those river mouths.”

(The Ocean Cleanup)

Boyan Slat dur­ing one of his re­search ex­pe­di­tions.

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