Polymers Are Forever
By Alan Weisman
May 24, 2007, 08:47
Alarming tales of a most prevalent and problematic substance
THE PORT OF PLYMOUTH in southwestern England is no longer listed among the scenic towns of the British Isles, although prior to World War II it would have qualified. During six nights of March and April 1941, Nazi bombs destroyed seventy-five thousand buildings in what is remembered as the Plymouth Blitz. When the annihilated city center was rebuilt, a modern concrete grid was superimposed on Plymouth’s crooked cobbled lanes, burying its medieval past in memory.
But the main history of Plymouth lies at its edge, in the natural harbor formed at the confluence of two rivers, the Plym and the Tamar, where they join the English Channel and the Atlantic Ocean. This is the Plymouth from which the Pilgrims departed; they named their American landfall across the sea in its honor. All three of Captain Cook’s Pacific expeditions began here, as did Sir Francis Drake’s circumnavigation of the globe. And, on December 27, 1831, H.M.S. Beagle set sail from Plymouth Harbor, with twenty-two-year-old Charles Darwin aboard.
University of Plymouth marine biologist Richard Thompson spends a lot of time pacing Plymouth’s historic edge. He especially goes in winter, when the beaches along the harbor’s estuaries are empty—a tall man in jeans, boots, blue windbreaker, and zippered fleece sweater, his bald pate hatless, his long fingers gloveless as he bends to probe the sand. Thompson’s doctoral study was on slimy stuff that mollusks such as limpets and winkles like to eat: diatoms, cyanobacteria, algae, and tiny plants that cling to seaweed. What he’s now known for, however, has less to do with marine life than with the growing presence of things in the ocean that have never been alive at all.
Although he didn’t realize it at the time, what has dominated his life’s work began when he was still an undergraduate in the 1980s, spending autumn weekends organizing the Liverpool contingent of Great Britain’s national beach cleanup. In his final year, he had 170 teammates amassing metric tons of rubbish along eighty-five miles of shoreline. Apart from items that apparently had dropped from boats, such as Greek salt boxes and Italian oil cruets, from the labels he could see that most debris was blowing east from Ireland. In turn, Sweden’s shores were the receptacles for trash from England. Any packaging that trapped enough air to protrude from the water seemed to obey the wind currents, which in these latitudes are easterly.
Smaller, lower-profile fragments, however, were apparently controlled by currents in the water. Each year, as he compiled the team’s annual reports, Thompson noticed more and more garbage that was smaller and smaller amid the usual bottles and automobile tires. He and another student began collecting sand samples along beach strand lines. They sieved the tiniest particles of whatever appeared unnatural, and tried to identify them under a microscope. This proved tricky. Their subjects were usually too small to allow them to pinpoint the bottles, toys, or appliances from which they sprang.
He continued working the annual cleanup during graduate studies at Newcastle. Once he completed his PhD and began teaching at Plymouth, his department acquired a Fourier Transform Infrared Spectrometer, a device that passes a microbeam through a substance, then compares its infrared spectrum to a database of known material. Now he could know what he was looking at, which only deepened his concern.
“Any idea what these are?” Thompson is guiding a visitor along the shore of the Plym River estuary, near where it joins the sea. With a full moonrise just a few hours off, the tide is out nearly two hundred meters, exposing a sandy flat scattered with bladderwrack and cockle shells. A breeze skims the tidal pools, shivering rows of reflected hillside housing projects. Thompson bends over the strand line of detritus left by the forward edge of waves lapping the shore, looking for anything recognizable: hunks of nylon rope, syringes, topless plastic food containers, half a ship’s float, pebbled remains of polystyrene packaging, and a rainbow of assorted bottle caps. Most plentiful of all are multicolored plastic shafts of cotton ear-swabs. But there are also the odd little uniform shapes he challenges people to identify. Among twigs and seaweed fibers in his fistful of sand are a couple dozen blue and green plastic cylinders about two millimeters high.
“They’re called nurdles. They’re the raw materials of plastic production. They melt these down to make all kinds of things.” He walks a little farther, then scoops up another handful. It contains more of the same plastic bits: pale blue ones, greens, reds, and tans. Each handful, he calculates, is about 20 percent plastic, and each holds at least thirty pellets.
“You find these things on virtually every beach these days. Obviously they are from some factory.”
However, there is no plastic manufacturing anywhere nearby. The pellets have ridden some current over a great distance until they were deposited here—collected and sized by the wind and tide.
IN THOMPSON’S LABORATORY AT THE UNIVERSITY of Plymouth, graduate student Mark Browne unpacks foil-wrapped beach samples that arrive in clear zip-lock bags sent by an international network of colleagues. He transfers these to a glass separating funnel, filled with a concentrated solution of sea salt to float off the plastic particles. He filters out some he thinks he recognizes, such as pieces of the ubiquitous colored ear-swab shafts—to check under the microscope. Anything really unusual goes to the FTIR Spectrometer.
Each takes more than an hour to identify. About one-third turn out to be natural fibers such as seaweed, another third are plastic, and another third are unknown—meaning that they haven’t found a match in their polymer database, or that the particle has been in the water so long its color has degraded, or that it’s too small for their machine, which analyzes fragments only to twenty microns—slightly thinner than a human hair.
“That means we’re underestimating the amount of plastic that we’re finding. The true answer is we just don’t know how much is out there.”
What they do know is that there’s much more than ever before. During the early twentieth century, Plymouth marine biologist Alistair Hardy developed an apparatus that could be towed behind an Antarctic expedition boat, ten meters below the surface, to sample krill—the ant-sized, shrimplike invertebrate on which much of the planet’s food chain rests. In the 1930s, he modified it to measure even smaller plankton. It employed an impeller to turn a moving band of silk, similar to how a dispenser in a public lavatory moves cloth towels. As the silk passed over an opening, it filtered plankton from water passing through it. Each band of silk had a sampling capacity of five hundred nautical miles. Hardy was able to convince English merchant vessels using commercial shipping lanes throughout the North Atlantic to drag his Continuous Plankton Recorder for several decades, amassing a database so valuable he was eventually knighted for his contributions to marine science.
He took so many samples from around the British Isles that only every second one was analyzed. Decades later, Richard Thompson realized that the ones that remained stored in a climate-controlled Plymouth warehouse were a time capsule containing a record of growing contamination. He picked two routes out of northern Scotland that had been sampled regularly: one to Iceland, one to the Shetland Islands. His team pored over rolls of silk reeking of chemical preservative, looking for old plastic. There was no reason to examine years prior to World War II because until then plastic barely existed, except for the Bakelite used in telephones and radios, appliances so durable they had yet to enter the waste chain. Disposable plastic packaging hadn’t yet been invented.
By the 1960s, however, they were seeing increasing numbers of increasing kinds of plastic particles. By the 1990s, the samples were flecked with triple the amount of acrylic, polyester, and crumbs of other synthetic polymers than had been present three decades earlier. Especially troubling was that Hardy’s plankton recorder had trapped all this plastic ten meters below the surface, suspended in the water. Since plastic mostly floats, that meant they were seeing just a fraction of what was actually there. Not only was the amount of plastic in the ocean increasing, but ever smaller bits of it were appearing—small enough to ride global sea currents.
Thompson’s team realized that slow mechanical action—waves and tides that grind against shorelines, turning rocks into beaches—were now doing the same to plastics. The largest, most conspicuous items bobbing in the surf were slowly getting smaller. At the same time, there was no sign that any of the plastic was biodegrading, even when reduced to tiny fragments.
“We imagined it was being ground down smaller and smaller, into a kind of powder. And we realized that smaller and smaller could lead to bigger and bigger problems.”
He knew the terrible tales of sea otters choking on poly-ethylene rings from beer six-packs; of swans and gulls strangled by nylon nets and fishing lines; of a green sea turtle in Hawai’i dead with a pocket comb, a foot of nylon rope, and a toy truck wheel lodged in its gut. His personal worst was a study on fulmar carcasses washed ashore on North Sea coastlines. Ninety-five percent had plastic in their stomachs—an average of forty-four pieces per bird. A proportional amount in a human being would weigh nearly five pounds.
There was no way of knowing if the plastic had killed them, although it was a safe bet that, in many, chunks of indigestible plastic had blocked their intestines. Thompson reasoned that if larger plastic pieces were breaking down into smaller particles, smaller organisms would likely be consuming them. He devised an aquarium experiment, using bottom-feeding lugworms that live on organic sediments, barnacles that filter organic matter suspended in water, and sand fleas that eat beach detritus. In the experiment, plastic particles and fibers were provided in proportionately bite-sized quantities. Each creature promptly ingested them.
When the particles lodged in their intestines, the resulting constipation was terminal. But if the pieces were small enough, they passed through the invertebrates’ digestive tracts and emerged, seemingly harmlessly, out the other end. Did that mean that plastics were so stable that they weren’t toxic? At what point would they start to naturally break down—and when they did, would they release some fearful chemicals that would endanger organisms some time far in the future?
Richard Thompson didn’t know. Nobody did, because plastics haven’t been around long enough for us to know how long they’ll last or what will happen to them. His team had identified nine different kinds in the sea so far, varieties of acrylic, nylon, polyester, polyethylene, polypropylene, and polyvinyl chloride. All he knew was that soon everything alive would be eating them.
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