(CNN) -- The massive amount of garbage in the ocean likely complicates the search for the remains of an Air France flight that went missing Monday near Brazil, oceanographers who spoke with CNN said.

Earlier this week, investigators said they had located pieces of the plane in the southern Atlantic Ocean, which might have given them clues to the origin of Air France Flight 447's crash.

But on Thursday, Brazilian officials said what they had found was nothing more than run-of-the-mill ocean trash.

This highlights a little-seen environmental problem: Scientists say the world's oceans are increasingly filled with junk -- everything from large items like refrigerators and abandoned yachts to small stuff like plastic bottles.

Much of the ocean trash is plastic, which means it won't go away for hundreds of years, if ever. And the problem has gotten so bad that soupy "garbage patches" have developed in several locations, called gyres, where ocean currents swirl.

One of them is estimated to be the size of Texas.

There are about five or six major trash-collecting gyres in the world's oceans, with the most famous located in the Pacific Ocean about midway between North America and Asia, experts said. Trash collects at these locations, where ocean currents swirl, and forms a gunk of small plastic pieces. See a map of Pacific Ocean debris »

There is not a major "trash island" near the site of the Air France plane crash in the south Atlantic, oceanographers said, but splitting currents do create a smaller area for trash to congregate.

"That area [of the crash site] has got lots of debris that's just out there, coming from Europe heading over the Americas," said Curtis Ebbesmeyer, a oceanographer and author of a book called "Flatsometrics and the Floating World." "And it's notoriously difficult to spot debris from the air."

The south Atlantic near Brazil is driven by two currents, one that pushes debris to the north, along the coast of Florida, and one that would push it to the south, perhaps all the way to the tip of South America, he said. So the plane's wreckage could span that massive area, he said.

Most debris from the crash of Air France Flight 447 would head toward Brazil and arrive within a couple of months; but wherever the remnants land, the plane debris would be difficult to distinguish from the mountains of trash that wash up on beaches every day, Ebbesmeyer said.

"The trouble is that there is so much debris on eastern Florida that's from South America. Anywhere, it's very unlikely that anyone will recover [the plane debris]," he said. "It's very likely that debris that would provide closure for loved ones would go in the Dumpster because [beachgoers] don't know what it is."

The search for signs of the Air France flight highlights what environmentalists say is a pressing issue for the world today: We produce a lot of trash that biodegrades slowly, and too much of it ends up in the ocean. Out at sea, plastics suffocate sea turtles and choke birds, which look at the bits of floating gunk as food.

Endangered sea turtles become entangled in discarded fishing line and also ingest plastic bags, like those from grocery stores, said Bamford.

"They love to eat jellyfish, and when they see a plastic bag it looks exactly like a jellyfish, basically," she said.

Still, scientists say they know relatively little about the scope of the problem and the effects that trash has on ocean life.

Finding answers to those unknowns is among the current initiatives of the National Oceanic and Atmospheric Administration, said Holly Bamford, director of the U.S. agency's marine debris program.

Enough is known about ocean trash to know that it's time to act, she said.

"It's a global problem. You can go do a collection almost anywhere and you'll probably come up with a piece of debris in your sample. The question is what all is out there and what is it doing," she said. "It's something that needs to be addressed."

About 80 percent of the trash that ends up in the ocean starts on land and is swept out to sea either from beaches or through waterways and sewer systems, according to the U.S. Environmental Protection Agency.

The garbage can make its way to the ocean via rivers from the very heart of a continent, Bamford said.

Once it hits the sea, ocean currents -- and to a lesser extent, wind -- determine where the trash goes. Since the mid-1900s, people have been making plastic, which decomposes much more slowly than other materials.

International treaties ban ship captains from dumping their trash into the sea, scientists said, but the rules are not well-enforced.

Education is the key to preventing trash from ending up in the ocean in the first place, said Peter Niiler, an oceanographer and distinguished researcher at the Scripps Institution of Oceanography.

Niiler said too little is known about the oceans, and there are gross misconceptions about their size.

"I think the [idea of an] ocean being an infinitely large thing comes from the fact that you've never been there or you don't have data from there. You don't know what's there. So you're just living on the coast and you can't hardly imagine going from North America to China," he said.

He added: "The ocean is just like land. It's part of our whole ecosystem of the whole earth. We know a great deal about land but we know very little about the oceans."

While they aren't likely to help with the plane search, volunteer groups seek to collect trash before it hits the ocean and is swept away to a garbage patch. The Ocean Conservancy says it organizes the largest of these efforts. Last year, 400,000 volunteers from 100 countries collected trash off of the beaches, preventing it from harming the ocean, said Tom McCann, a spokesman for the group.

"It's entirely preventable," he said of the problem of trash in the ocean. "It's something we can solve ourselves."

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