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Polymers Are Forever
Alan Weisman, Orion Magazine
Alarming tales of a most prevalent and problematic substance
…”Plastics haven’t been around long enough for microbes to develop the enzymes to handle it, so they can only biodegrade the very-low-molecular-weight part of the plastic”-meaning, the smallest, already broken polymer chains. Although truly biodegradable plastics derived from natural plant sugars have appeared, as well as biodegradable polyester made from bacteria, the chances of them replacing the petroleum-based originals aren’t great.
“Since the idea of packaging is to protect food from bacteria,” Andrady observes, “wrapping leftovers in plastic that encourages microbes to eat it may not be the smartest thing to do.”
But even if it worked, or even if humans were gone and never produced another nurdle, all the plastic already produced would remain-how long?
“Egyptian pyramids have preserved corn, seeds, and even human parts such as hair because they were sealed away from sunlight with little oxygen or moisture,” says Andrady, a mild, precise man with a broad face and a clipped, persuasively reasonable voice. “Our waste dumps are somewhat like that. Plastic buried where there’s little water, sun, or oxygen will stay intact a long time. That is also true if it is sunk in the ocean, covered with sediment. At the bottom of the sea, there’s no oxygen, and it’s very cold.”
He gives a clipped little laugh. “Of course,” he adds, “we don’t know much about microbiology at those depths. Possibly anaerobic organisms there can biodegrade it. It’s not inconceivable. But no one’s taken a submersible down to check. Based on our observations, it’s unlikely. So we expect much-slower degradation at the sea bottom. Many times longer. Even an order of magnitude longer.”
An order of magnitude-that’s ten times-longer than what? One thousand years? Ten thousand?
No one knows, because no plastic has died a natural death yet. It took today’s microbes that break hydrocarbons down to their building blocks a long time after plants appeared to learn to eat lignin and cellulose. More recently, they’ve even learned to eat oil. None can digest plastic yet, because fifty years is too short a time for evolution to develop the necessary biochemistry.
Alan Weisman’s article in this issue is an abridged excerpt from his book “The World Without Us,” published by St. Martin’s Press in July, 2007 and used by permission. He lives in Tucson and teaches at the University of Arizona.
Excellent article on a subject that’s seldom reported on.
Related from the Guardian (May 16): small town in Devon has become the first place in Europe to turn its back on plastic shopping bags
Frenetic lifestyle puts the boots to leisurely strolls
If it seems sometimes that the pace of life has quickened, rest assured that it has — by about 10 per cent over the last decade.
We can thank Richard Wiseman, a professor of psychology at the University of Hertfordshire in England, for quantifying the unquantifiable. He did it by comparing the time it took pedestrians in cities around the world to walk 60 feet (18.3 metres) in a 1994 study with recorded times of city dwellers traversing the identical length of unobstructed pavement today.
The results show that on average we move at about 3.5 mph (5.6 km per hour), or 10 per cent faster than in the early 1990s, an increase Wiseman attributed to a frenetic lifestyle driven by technology and 24-hour availability.
“The psychology is basically that people’s walking pace is determined by how much they think they’re in a hurry; how quickly they think they should be doing things,” he said. “What’s amazing is that these days, you press send on an e-mail and, if someone hasn’t responded in 10 minutes, you think: ‘Where are they?’ “
Not surprisingly, the pace in the so-called Asian Tigers has quickened the most, with pedestrians in Singapore walking 30 per cent faster than a decade ago, covering the distance in a mere 10.4 seconds; and in Guangzhou (China) 20 per cent faster, in 10.94 seconds.
(11 May 2007)