WASHINGTON — The amount of plastic trash in the ocean doesn't seem to be growing, and environmentalists are puzzled.
A 22-year study indicates that the amount of plastic corralled by currents into a floating junkyard in the Atlantic Ocean has not increased.
"We know that global production of plastics has increased substantially over the time period" and disposal also has increased, said Kara Lavender Law of the Sea Education Association in Woods Hole, Mass.
"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 in a telephone interview.
Over the course of the study more than 64,000 individual plastic pieces were collected at 6,100 locations that were sampled, Law and colleagues report in Thursday's online edition of the journal Science.
Researchers worry about plastic in the oceans because it can endanger seabirds, turtles and other sea life which eat it, or become entangled. A floating trash field also has been reported in the Pacific Ocean.
While the researchers found significant year-to-year changes in the amount of plastic in the Atlantic, averaging over time they found no significant increase.
The annual trips to the Atlantic junkyard use plankton nets to skim the surface, collecting tiny pieces, and students then pick out the plastic pieces with tweezers.
The exact expanse of the Atlantic trash field has not been determined, Law said. It is located in the Atlantic at about the same latitude as Atlanta.
Law suggested that the plastic may be breaking unto smaller pieces and passing through the nets, or that biological growth on the plastic may be causing it to become more dense and sink into the ocean where the nets miss it.
Wind patterns and currents do not seem to have changed, she said, so the trash should still be collecting at the same place.
The research was funded by the National Science Foundation.