2014年7月4日金曜日

All the plastic trash in the ocean gone!

Researchers estimate the  the total amount of floating plastic debris in open ocean at 7,000 to 35,000 tons – far less than the 1 million tonnes previously estimated.


Daily Mail
2 July 2014


Plastic junk is floating widely on the world's oceans, but there is significantly less of it than expected, researchers have warned.

Researchers towed a mesh net at 141 sites to monitor floating debris.

They estimate the  the total amount of floating plastic debris in open ocean at 7,000 to 35,000 tons - far less than the 1 million tonnes previously estimated.

Such ocean pollution has drawn attention in recent years because of its potential harm to fish and other wildlife.

Andres Cozar of the University of Cadiz in Spain, an author of the study, said that's a lot less than the 1 million tons he had extrapolated from data reaching back to the 1970s.

The new estimate includes only floating debris, not plastic that may reside beneath the surface or on the ocean floor.

Of the plastic pieces caught by the ship's net, most were less than about a fifth of an inch long.

Some floating pieces start out small, like the microbeads found in some toothpastes and cosmetics or industrial pellets used to make plastic products.

Other small pieces can result when wave action breaks up larger objects, like bottle caps, detergent bottles and shopping bags.

The net turned up fewer small pieces than expected, and it will be important to figure out why, researchers said.

While the research showed plastic to be distributed widely, concentrations were highest in five areas that were predicted by ocean current patterns.

Kara Lavender Law, who studies plastic pollution at the Sea Education Association in Woods Hole, Massachusetts, said the study provides the first global estimate she knows of for floating plastic debris.

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