21. Feb, 2016

Cleaning up the plastic soup

Plastic soup  refers  to the  immense quantities of plastic drifting  in  superficial layers of the oceans. Areas where plastic soup accumulates and circulates in large circles are the gyri.  Gyri are slow currents driven mostly  by Westerly winds and influenced by  the Coriolis  effect  causing  a bend  of 20-45° to the right, on the northern hemisphere. On the southern hemisphere the gyre moves counter clockwise. There are two notorious gyri in the Pacific: the North Pacific Gyre and South Pacific Gyre (see picture above). The North Pacific Gyre is also  known as the  ‘great garbage patch’,  because of its accumulation of large quantities of plastic.  Its estimated to  consist of  100.000 billion  tons of garbage. Mostly larger pieces, but also smaller pieces.  The smaller pieces pulverize under the influence  of salt water and photo degradation, and enter the food chain  of marine mammals, fishes, tortoises and the albatros. These high density particles  are difficult to spot with the naked eye and can sink  to lower layers of the oceans.

A  Dutch  organization master minded by Boyan Slatan and several  hydrodynamic engineers from  the Technical University of Delft started an ambitious project to clean up the garbage patches.  Basic elements are long distance barrier segments floating in the sea, and a central platform collecting the garbage. They focus on the North Pacific where about 1/3 of all oceanic plastic is concentrated in an area between Hawaii and California. The project  has now  entered a new testing stage. Engineers are currently installing a scale model of the Ocean Cleanup Array in an offshore basin at the world-renowned Maritime Research Institute Netherlands (MARIN).