January 19, 2009 (Taken from canada.com) - Bits of plastic turn parts of the ocean into a deadly "soup"
Ever wonder what happened to that candy wrapper or water bottle you accidentally dropped on the sidewalk?If you think it wound up in a garbage dump or recycling depot, think again. A lot of the plastic debris that litters city streets is flushed into sewers. From there it goes into the country's waterways and eventually winds up in the ocean.
Scientists are growing alarmed about massive floating dumps that are believed to be building up in the calm centres of the gyres in the middle of nearly all of the world's oceans.
The best-known patch, known by some as the Great Pacific Ocean Garbage Patch, consists of an estimated 100 million tonnes of plastic debris that has accumulated in the North Pacific gyre. Environmentalists call it the Pacific Trash Vortex.
It is estimated to be anywhere from 700,000 square kilometres - half the size of Quebec - up to 15 million square kilometres, depending on how it is measured. Plastic from the vortex is increasingly washing up on Hawaiian atolls and being found in the guts of seabirds and fish. An estimated 100,000 marine mammals die each year from eating or being entangled in debris - mostly plastic - in the North Pacific alone. Hence the vortex's other nickname: the Plastic Killing Fields.
Plastic in the sea doesn't biodegrade like other garbage. Instead, it slowly breaks up into tinier and tinier pieces that float on the ocean surface or sink to the sea bottom and can take years to finally reach the ocean gyres. Sailors used to fear getting stuck in gyres because the paltry wind could leave ships stranded without headway for weeks on end.
The vortexes are increasingly seen as environmental disaster zones. Plastic contains many toxic chemicals; it also soaks up other dangerous substances already present in the ocean, like carcinogenic PCBs and DDT. Eighty per cent of the plastic in the ocean gyres is believed to come from the land, while the remainder is litter from cargo ships, cruise boats and other sea vessels.
"Next time there's a rainstorm, just look at what's in the gutter," said Elaine MacDonald, a Toronto scientist with the environmental group Ecojustice Canada.
"The sewers are directly connected to our rivers and lakes."
Richard Thompson, a marine biologist at England's University of Plymouth, is one of the few scientists studying plastic in the oceans. In a landmark study in 2004, Thompson found microscopic pieces of plastic in the water that had been scooped up with plankton samples in the North Atlantic starting in the 1960s, but there was four times as much plastic in the most recent samples, coinciding with a 25-fold increase in plastic production worldwide between 1960 and 2000.
Even more alarming, the water samples were from an area of the Atlantic north of Britain that isn't even in the gyre. No one has ever studied the amount of plastic in the Atlantic gyre itself.
Thompson's studies reported other alarming findings:
- 98 per cent of dead seabirds studied in northern Europe have plastic in their stomachs.
- more than 260 animal species are known to eat or get entangled in plastic, including turtles, fish, marine mammals, even small creatures like mussels, barnacles and beach fleas.
- 10 per cent of all plastic debris eventually winds up in the sea.
Ocean currents and winds are slowly bringing all that debris to the centre of five major ocean gyres in the North and South Atlantic, North and South Pacific and the Indian Oceans, said Marieta Francis, executive director of the Algalita Marine Research Foundation, based in Long Beach, Calif.
But despite the ever-growing plastic blobs in the oceans, the Pacific gyre is the only one that has been studied.
The Algalita foundation's founder, an avid boater named Charles Moore, chanced upon the Pacific Garbage Patch during a 1997 yacht race.
"Here I was in the middle of the ocean, and there was nowhere I could go to avoid the plastic," he told the U.S. News and World Report.
The vortex was in the North Pacific gyre, where a high-pressure zone forces debris into a central area that has low currents and winds.
Moore returned with a scientific vessel to study the vortex and found up to 970,000 pieces of plastic per square kilometre in some areas. That was triple the density found in a landmark 1988 study in the western Pacific by the U.S. National Oceanic and Atmospheric Administration. That study found one area 1,000 kilometres east of Japan that had 315,000 pieces of plastic per square kilometre.
While much of the debris is large and conspicuous, most of it has disintegrated after years of washing around in the ocean.
The plastic pieces are usually five millimetres across or less - about the width of a pea - and must be scooped up in nets finer than a window screen.
"It's not quite what people think. It's like a soup," said Algalita's Francis.
In the Atlantic, the only research on plastic garbage is more than 30 years old. A survey in the northeastern Atlantic in the early 1970s found 160,000 pieces of plastic per square kilometre in some areas.
Back in Canada, the growing plastic vortexes still seem far from the official radar. At the Department of Fisheries and Oceans, oceanographer Denis Gilbert, one of Canada's leading experts on the Atlantic environment, said he'd never even heard about plastic accumulating in the Atlantic gyre.
"We have no one working on that," he said.
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