August 20, 2010

Experts Puzzled Over “˜Missing’ Plastic Trash In Ocean

Environmentalists are mystified over the of results of a 22-year study published Thursday, which finds that the amount of plastic trash corralled by Atlantic ocean currents has remained steady for more than two decades.

"We know that global production of plastics has increased substantially over the time period" said Kara Lavender Law of the Sea Education Association in Massachusetts

Disposal also has increased, she added.

"If there is more plastic trash it's hard to believe more is not making it into the ocean. There is missing plastic out there," she said during an interview with the Associated Press.

More than 64,000 individual plastic pieces were collected at 6,100 sampled locations over the course of the study, said Law and her colleagues in a report published in the journal Science.

Experts worry about plastic accumulating in the oceans because it can endanger various forms of sea life that consume or become entangled in the trash.  

A floating junkyard known as the Great Pacific Garbage Patch has also has been reported in the Pacific Ocean hundreds of miles off the southern California coast.

In the current study, scientists did observe substantial year-over-year changes in the amount of plastic in the Atlantic Ocean, but over time they found no significant increase in the average amount of plastic trash.

The researchers made yearly trips to the Atlantic trash field, using plankton nets to skim and gather tiny pieces of material from the ocean's surface. Students then used tweezers to separate the plastic components.

Although the precise area of the Atlantic trash field has not yet been established, the junkyard is located at roughly the same latitude as Atlanta, Georgia, Law said.

The plastic may be disintegrating into smaller pieces and passing through the nets, she hypothesized.  Or, perhaps biological growth may be causing the plastic to become denser, forcing it to sink below the surface beyond the reach of the nets, she said.

There does not appear to be any changes in wind patterns or currents that would explain the study's findings, so the trash should still be collecting at the same place, she added.

The study, funded by the National Science Foundation, was published in Thursday's online edition of the journal Science.  An abstract can be viewed at http://www.sciencemag.org/cgi/content/abstract/science.1192321v1.


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