The Great Pacific Ocean Garbage Patch
Not all garbage ends up at the dump. A river, 2)sewer or beach can't catch everything the rain washes away, either. In fact, Earth's largest 3)landfill isn't on land at all.
The Great Pacific Garbage Patch stretches for hundreds of miles across the North Pacific Ocean, forming a 4)nebulous, floating 5)junk yard on the 6)high seas. It's the 7)poster child for a worldwide problem: plastic that begins in human hands yet ends up in the ocean, often inside animals' stomachs or around their necks. This marine debris has 8)sloshed into the public spotlight recently, thanks to growing media coverage as well as scientists and explorers who are increasingly visiting the North Pacific to see plastic pollution in action.
A Galaxy of Garbage
The Great Pacific Garbage Patch has sometimes been described as a “trash island,” but that's a 9)misconception, says Holly Bamford, director of 10)NOAA's Marine Debris Program. If only things were that simple. “We could just go out there and 11)scoop up an island,” Bamford says. “If it was one big mass, it would make our jobs a whole lot easier.”http://www.24en.com 爱思英语网
Instead, it's like a galaxy of garbage, 12)populated by billions of smaller trash islands that may be hidden underwater or spread out over many miles. That can make it 13)maddeningly difficult to study—Bamford says we still don't know how big the garbage patch is, despite the 14)oft-cited claim that it's as big as Texas.
Problems Begin from Plastic
While there's still much we don't understand about the garbage patch, we do know that most of it's made of plastic. And that's where the problems begin.http://www.24en.com 爱思英语网
Unlike most other trash, plastic isn't 15)biodegradable—i.e., the 16)microbes that break down other substances don't recognize plastic as food, leaving it to float there forever. Sunlight does eventually “17)photodegrade” the 18)bonds in plastic 19)polymers, reducing it to smaller and smaller pieces, but that just makes matters worse. The plastic still never goes away; it just becomes 20)microscopic and may be eaten by tiny marine organisms, entering the food chain.
About 80 percent of debris in the Great Pacific Garbage Patch comes from land, much of which is plastic bags, bottles and various other consumer products. 21)Free-floating fishing nets make up another 10 percent of all marine litter. The rest comes largely from recreational 22)boaters, 23)offshore 24)oil rigs and large cargo ships, which drop about 10,000 steel shipping containers into the sea each year, full of things like hockey gloves, computer monitors, 25)resin 26)pellets and 27)LEGOs. But despite such diversity—and plenty of metal, glass and rubber in the garbage patch—the majority of material is still plastic, since most everything else sinks or biodegrades before it gets there.
Three Main Problems
Marine debris threatens environmental health in several ways. Here are the main ones:
28)Entanglement: The growing number of abandoned plastic fishing nets is one of the greatest dangers from marine debris, Bamford says. The nets entangle seals, sea turtles and other animals in a phenomenon known as “29)ghost fishing,” often drowning them. With more fishermen from developing countries now using plastic for its low cost and high durability, many abandoned nets can continue fishing on their own for months or years.http://www.24en.com 爱思英语网
Virtually any marine life can be endangered by plastic, but sea turtles seem especially 30)susceptible. In addition to being entangled by fishing nets, they often swallow plastic bags, mistaking them for 31)jellyfish, their main prey.http://www.24en.com 爱思英语网
Small surface debris: Plastic resin pellets are another common piece of marine debris; the tiny, industrial-use 32)granules are shipped 33)in bulk around the world, melted down at manufacturing sites and 34)remolded into commercial plastics. Being so small and plentiful, they can easily get lost along the way, washing through the 35)watershed with other plastics and into the sea.
36)Albatross parents leave their chicks on land in Pacific islands to go 37)scour the ocean surface for food, namely protein-rich fish eggs. These are small dots 38)bobbing just below the surface, and look unfortunately similar to resin pellets. Well-meaning albatrosses scoop up these pellets—along with other floating trash such as cigarette lighters—and return to feed the indigestible plastic to their chicks, which eventually die of starvation or 39)ruptured organs.
Photodegradation: As sunlight breaks down floating debris, the surface water thickens with 40)suspended plastic bits. This is bad for a couple of reasons. First, Bamford says, is plastic's “inherent 41)toxicity”: It often contains 42)colorants and chemicals like 43)bisphenol-A, which studies have linked to various environmental and health problems, and these toxins may 44)leach out into the seawater. Plastic has also been shown to absorb pre-existing organic pollutants like 45)PCBs from the surrounding seawater, which can enter the food chain—along with BPA and other inherent toxins—if the plastic bits are accidentally 46)ingested by marine life.
Things that We Can Do
The discoverer of the Great Pacific Garbage Patch, Capt. Charles Moore, once said a cleanup effort “would bankrupt any country and kill wildlife in the nets as it went.” “He makes a really good point there,” Bamford says. “It's very difficult.” Still, NOAA conducts 47)flyovers to study the garbage patch, and two research teams recently sailed there to collect debris and water samples. Meanwhile, the international 48)Project Kaisei team also recently spent ime in the garbage patch, studying its contents in hopes of eventually recycling them or turning them into fuel.http://www.24en.com 爱思英语网
Ultimately, more plastic recycling and wider use of biodegradable materials is the best hope for controlling these garbage patches, Bamford says, but that's an 49)uphill battle.
“We need to turn off the taps at the source. We need to educate people on the proper disposal of things that do not break up, like plastics,” she says. “Opportunities for recycling have to increase, but, you know, some people buy three bottles of water a day. As a society, we have to get better at reusing what we buy.”