published on 15 March 2021 in water
Transition paths of plastic in oceans have been identified
Sea currents and winds transport tonnes of plastic from the coast to the open sea every day and then channel it into ocean gyres, where plastic islands form. There are six floating plastic islands in the oceans: two in the Pacific, two in the Atlantic, one in the Indian Ocean and a smaller one recently spotted in the Arctic Ocean.
The paths followed by plastics and microplastics in the seas, to date little known, have been reconstructed thanks to a statistical model developed by a group of American and German researchers led by fluid dynamics physics expert Philippe Miron of the University of Miami. The research, published in Chaos analyses the transition paths along which debris is transported from the coast to the Garbage Patches in the middle of the oceans in relation to the varying strength of currents acting in subtropical areas. The researchers, who also used historical data from ocean buoys, developed a sort of map to organise ocean clean-up or prevention operations.
The mathematical model identified “a transitional channel linking the Great Pacific Garbage Patch with the coasts of Eastern Asia,” Miron explained. Confirming the “notable source of plastic pollution” originating from Asia. It also confirmed that the Indian Ocean gyre acts as a “trap” for plastics, with other significant deposits in fact found in the Bay of Bengal. In the Atlantic, however, plastics are most easily caught in the Gulf of Guinea off Africa. The South Pacific gyre is the most persistent, as the trapped plastics “are very unlikely to manage to escape”. The work of these scholars may have important implications for the ongoing work of cleaning up the oceans.