Sunday, February 28, 2010

Pacific Garbage Patch is Hawai'i-bound

When anything slips out of the Great Pacific Garbage Patch, say hello. Because chances are it ends up on a Hawaii beach.

Teams of researchers have been working on the fate of marine debris in both the Atlantic and Pacific.

(Image: This Laysan albatross chick died with its belly full of plastic, some of which may have been picked up by its parents in the Great Pacific Garbage Patch. A lesson about controlling the flow of plastic debris into the marine environment.)

“In the North Pacific, Hawai'i is the final destination of marine debris,” said Nikolai Maximenko, a senior researcher with the International Pacific Research Center, and the University of Hawai'i's School of Ocean and Earth Science and Technology.

He reported last week from the American Geophysical Union 2010 Ocean Sciences Meeting in Portland, Oregon.

As we understand it, when trash gets lost or dumped off fishing boats, falls off big ships or washes into the ocean from the shore in the North Pacific, it begins a nearly endless transit around the ocean on a vast current system.

A large amount of that trash slowly moves toward the interior of the the North Pacific Current, and eventually gets trapped in the immense field of garbage in the eastern North Pacific, between Hawai'i and California.

And when currents and winds drive anything out of that system, it tends to get swept south and westward. The only thing in its way at that point is the 1,400-mile-long Hawaiian archipelago.

So our Hawaiian reefs and beaches get trashed with tangles of rope and net, plastic tubes from Japanese oyster farms, bottles, multicolored cigarette lighters, and endless fields of tiny bits of unidentifiable plastic.

A research program in the Atlantic, involving thousands of graduate students, reported on 6,100 plankton net tows in that ocean. They found that 62 percent of the nets contained plastic—64,000 pieces of plastic. Most of it, 83 percent, was found in the central latitudes, between 22 and 38 degrees north, said Kara Lavender Law, Oceanography Faculty Scientist of the Sea Education Association at Woods Hole, Massachusetts.

Another Woods Hole faculty scientist, Giora Proskurowski, said that while researchers have towed nets through the water for hundreds of miles, no one knows just how much of that stuff is out there, in part because any amount of wind or wave causes much of the debris to mix deep into the upper layers of the ocean. There, it doesn't show up in surface-towed plankton nets.

If you do a tow on a dead calm day, the stuff floats to the surface and you get a lot. If you tow when there's any kind of weather, the results under-represent reality, he said.

Law said that the majority of the smaller bits of plastic are not identifiable as to their source, unless they are bits of fishing line or industrial plastic pellets. Some plastic debris is denser that seawater and sinks to the bottom, where its impacts have not been well studied.

© Jan TenBruggencate 2010

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