Chapter 9: Polymers are Forever
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 75,000 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 22-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 85
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 of the 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 Ph.D. 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 200 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. Amid twigs and seaweed fibers in his fistful of sand are a
couple of 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 30 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 20 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 20th century, Plymouth marine biologist
Alistair Hardy developed an apparatus that could be towed behind an
Antarctic expedition boat, 10 meters below the surface, to sample
krill—an ant-sized, shrimp-like 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
500 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 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 was present three decades
earlier. Especially troubling was that Hardy’s plankton recorder had
trapped all this plastic 10 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 polyethylene rings from beer six-packs; of swans and gulls strangled
by nylon nets and fishing lines; of a green sea turtle in Hawaii 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 44 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-size
quantities. Each creature promptly ingested them.
When the particles lodged in their intestines, the
resulting constipation was terminal. If they 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 sometime 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 happens 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.
“When they get as small as powder, even zooplankton will swallow them.”
Two sources of tiny plastic particles hadn’t
before occurred to Thompson. Plastic bags clog everything from sewer
drains to the gullets of sea turtles who mistake them for jellyfish.
Increasingly, purportedly biodegradable versions were available.
Thompson’s team tried them. Most turned out to be just a mixture of
cellulose and polymers. After the cellulose starch broke down,
thousands of clear, nearly invisible plastic particles remained.
Some bags were advertised to degrade in compost
piles as heat generated by decaying organic garbage rises past 100°F.
“Maybe they do. But that doesn’t happen on a beach, or in salt water.”
He’d learned that after they tied plastic produce bags to moorings in
Plymouth Harbor. “A year later you could still carry groceries in them.”
Even more exasperating was what his Ph.D. student
Mark Browne discovered while shopping in a pharmacy. Browne pulls open
the top drawer of a laboratory cabinet. Inside is a feminine cornucopia
of beauty aids: shower massage creams, body scrubs, and hand cleaners.
Several are by boutique labels: Neova Body Smoother, SkinCeuticals Body
Polish, and DDF Strawberry Almond Body Polish. Others are international
name brands: Pond’s Fresh Start, a tube of Colgate Icy Blast
toothpaste, Neutrogena, Clearasil. Some are available in the United
States, others only in the United Kingdom. But all have one thing in
common.
“Exfoliants: little granules that massage you as
you bathe.” He selects a peach-colored tube of St. Ives Apricot Scrub;
its label reads, 100% natural exfoliants. “This stuff is okay. The
granules are actually chunks of ground-up jojoba seeds and walnut
shells.” Other natural brands use grape seeds, apricot hulls, coarse
sugar, or sea salt. “The rest of them,” he says, with a sweep of his
hand, “have all gone to plastic.”
On each, listed among the ingredients are
“micro-fine polyethylene granules,” or “polyethylene micro-spheres,” or
“polyethylene beads.” Or just polyethylene.
“Can you believe it?” Richard Thompson demands of
no one in particular, loud enough that faces bent over microscopes rise
to look at him. “They’re selling plastic meant to go right down the
drain, into the sewers, into the rivers, right into the ocean.
Bite-size pieces of plastic to be swallowed by little sea creatures.”
Plastic bits are also increasingly used to scour
paint from boats and aircraft. Thompson shudders. “One wonders where
plastic beads laden with paint are disposed. It would be difficult to
contain them on a windy day. But even if they’re contained, there’s no
filter in any sewage works for material that small. It’s inevitable.
They end up in the environment.”
He peers into Browne’s microscope at a sample from
Finland. A lone green fiber, probably from a plant, lies across three
bright blue threads that probably aren’t. He perches on the countertop,
hooking his hiking boots around a lab stool. “Think of it this way.
Suppose all human activity ceased tomorrow, and suddenly there’s no one
to produce plastic anymore. Just from what’s already present, given how
we see it fragmenting, organisms will be dealing with this stuff
indefinitely. Thousands of years, possibly. Or more.”
A
In one sense, plastics have been around for
millions of years. Plastics are polymers: simple molecular
configurations of carbon and hydrogen atoms that link together
repeatedly to form chains. Spiders have been spinning polymer fibers
called silk since before the Carboniferous Age, whereupon trees
appeared and started making cellulose and lignin, also natural
polymers. Cotton and rubber are polymers, and we make the stuff
ourselves, too, in the form of collagen that comprises, among other
things, our fingernails.
Another natural, moldable polymer that closely
fits our idea of plastics is the secretion from an Asian scale beetle
that we know as shellac. It was the search for an artificial shellac
substitute that one day led chemist Leo Baekeland to mix tarry carbolic
acid—phenol—with formaldehyde in his garage in Yonkers, New York. Until
then, shellac was the only coating available for electric wires and
connections. The moldable result became Bakelite. Baekeland became very
wealthy, and the world became a very different place.
Chemists were soon busy cracking long hydrocarbon
chain molecules of crude petroleum into smaller ones, and mixing these
fractionates to see what variations on Baekeland’s first man-made
plastic they could produce. Adding chlorine yielded a strong, hardy
polymer unlike anything in nature, known today as PVC. Blowing gas into
another polymer as it formed created tough, linked bubbles called
polystyrene, often known by the brand name Styrofoam. And the continual
quest for an artificial silk led to nylon. Sheer nylon stockings
revolutionized the apparel industry, and helped to drive acceptance of
plastic as a defining achievement of modern life. The intercession of
World War II, which diverted most nylon and plastic to the war effort,
only made people desire them more.
After 1945, a torrent of products the world had
never seen roared into general consumption: acrylic textiles,
Plexiglass, polyethylene bottles, polypropylene containers, and “foam
rubber” polyurethane toys. Most world-changing of all was transparent
packaging, including self-clinging wraps of polyvinyl chloride and
polyethylene, which let us see the foods wrapped inside them and kept
them preserved longer than ever before.
Within 10 years, the downside to this wonder
substance was apparent. Life Magazine coined the term “throwaway
society,” though the idea of tossing trash was hardly new. Humans had
done that from the beginning with leftover bones from their hunt and
chaff from their harvest, whereupon other organisms took over. When
manufactured goods entered the garbage stream, they were at first
considered less offensive than smelly organic wastes. Broken bricks and
pottery became the fill for the buildings of subsequent generations.
Discarded clothing reappeared in secondary markets run by ragmen, or
were recycled into new fabric. Defunct machines that accumulated in
junkyards could be mined for parts or alchemized into new inventions.
Hunks of metal could simply be melted down into something totally
different. World War II—at least the Japanese naval and air portion—was
literally constructed out of American scrap heaps.
Stanford archaeologist William Rathje, who has
made a career of studying garbage in America, finds himself continually
disabusing waste-management officials and the general public of what he
deems a myth: that plastic is responsible for overflowing landfills
across the country. Rathje’s decades-long Garbage Project, wherein
students weighed and measured weeks’ worth of residential waste,
reported during the 1980s that, contrary to popular belief, plastic
accounts for less than 20 percent by volume of buried wastes, in part
because it can be compressed more tightly than other refuse. Although
increasingly higher percentages of plastic items have been produced
since then, Rathje doesn’t expect the proportions to change, because
improved manufacturing uses less plastic per soda bottle or disposable
wrapper.
The bulk of what’s in landfills, he says, is
construction debris and paper products. Newspapers, he claims, again
belying a common assumption, don’t biodegrade when buried away from air
and water. “That’s why we have 3,000-year-old papyrus scrolls from
Egypt. We pull perfectly readable newspapers out of landfills from the
1930s. They’ll be down there for 10,000 years.”
He agrees, though, that plastic embodies our
collective guilt over trashing the environment. Something about plastic
feels uneasily permanent. The difference may have to do with what
happens outside landfills, where a newspaper gets shredded by wind,
cracks in sunlight, and dissolves in rain—if it doesn’t burn first.
What happens to plastic, however, is seen most
vividly where trash is never collected. Humans have continuously
inhabited the Hopi Indian Reservation in northern Arizona since AD
1000—longer than any other site in today’s United States. The principal
Hopi villages sit atop three mesas with 360° views of the surrounding
desert. For centuries, the Hopis simply threw their garbage, consisting
of food scraps and broken ceramic, over the sides of the mesas. Coyotes
and vultures took care of the food wastes, and the pottery sherds
blended back into the ground they came from.
That worked fine until the mid-20th century. Then,
the garbage tossed over the side stopped going away. The Hopis were
visibly surrounded by a rising pile of a new, nature-proof kind of
trash. The only way it disappeared was by being blown across the
desert. But it was still there, stuck to sage and mesquite branches,
impaled on cactus spines.
South of the Hopi Mesas rise the 12,500-foot San
Francisco Peaks, home to Hopi and Navajo gods who dwell among aspens
and Douglas firs: holy mountains cloaked in purifying white each
winter—except in recent years, because snow now rarely falls. In this
age of deepening drought and rising temperatures, ski lift operators
who, the Indians claim, defile sacred ground with their clanking
machines and lucre, are being sued anew. Their latest desecration is
making artificial snow for their ski runs from wastewater, which the
Indians liken to bathing the face of God in shit.
East of the San Francisco Peaks are the even
taller Rockies; to their west are the Sierra Madres, whose volcanic
summits are higher still. Impossible as it is for us to fathom, all
these colossal mountains will one day erode to the sea—every boulder,
outcrop, saddle, spire, and canyon wall. Every massive uplift will
pulverize, their minerals dissolving to keep the oceans salted, the
plume of nutrients in their soils nourishing a new marine biological
age even as the previous one disappears beneath their sediments.
Long before that, however, these deposits will
have been preceded by a substance far lighter and more easily carried
seaward than rocks or even grains of silt.
Capt. Charles Moore of Long Beach, California,
learned that the day in 1997 when, sailing out of Honolulu, he steered
his aluminum-hulled catamaran into a part of the western Pacific he’d
always avoided. Sometimes known as the horse latitudes, it is a
Texas-sized span of ocean between Hawaii and California rarely plied by
sailors because of a perennial, slowly rotating high-pressure vortex of
hot equatorial air that inhales wind and never gives it back. Beneath
it, the water describes lazy, clockwise whorls toward a depression at
the center.
Its correct name is the North Pacific Subtropical
Gyre, though Moore soon learned that oceanographers had another label
for it: the Great Pacific Garbage Patch. Captain Moore had wandered
into a sump where nearly everything that blows into the water from half
the Pacific Rim eventually ends up, spiraling slowly toward a widening
horror of industrial excretion. For a week, Moore and his crew found
themselves crossing a sea the size of a small continent, covered with
floating refuse. It was not unlike an Arctic vessel pushing through
chunks of brash ice, except what was bobbing around them was a fright
of cups, bottle caps, tangles of fish netting and monofilament line,
bits of polystyrene packaging, six-pack rings, spent balloons, filmy
scraps of sandwich wrap, and limp plastic bags that defied counting.
Just two years earlier, Moore had retired from his
wood-furniture-finishing business. A lifelong surfer, his hair still
ungrayed, he’d built himself a boat and settled into what he planned to
be a stimulating young retirement. Raised by a sailing father and
certified as a captain by the U.S. Coast Guard, he started a volunteer
marine environmental monitoring group. After his hellish mid-Pacific
encounter with the Great Pacific Garbage Patch, his group ballooned
into what is now the Algita Marine Research Foundation, devoted to
confronting the flotsam of a half century, since 90 percent of the junk
he was seeing was plastic.
What stunned Charles Moore most was learning where
it came from. In 1975, the U.S. National Academy of Sciences had
estimated that all oceangoing vessels together dumped 8 million pounds
of plastic annually. More recent research showed the world’s merchant
fleet alone shamelessly tossing around 639,000 plastic containers every
day. But littering by all the commercial ships and navies, Moore
discovered, amounted to mere polymer crumbs in the ocean compared to
what was pouring from the shore.
The real reason that the world’s landfills weren’t
overflowing with plastic, he found, was because most of it ends up in
an ocean-fill. After a few years of sampling the North Pacific gyre,
Moore concluded that 80 percent of mid-ocean flotsam had originally
been discarded on land. It had blown off garbage trucks or out of
landfills, spilled from railroad shipping containers and washed down
storm drains, sailed down rivers or wafted on the wind, and found its
way to this widening gyre.
“This,” Captain Moore tells his passengers, “is
where all the things end up that flow down rivers to the sea.” It is
the same phrase geologists have uttered to students since the beginning
of science, describing the inexorable processes of erosion that reduce
mountains to dissolved salts and specks small enough to wash to the
ocean, where they settle into layers of the distant future’s rocks.
However, what Moore refers to is a type of runoff and sedimentation
that the Earth had hitherto never known in 5 billion years of geologic
time—but likely will henceforth.
During his first 1,000-mile crossing of the gyre,
Moore calculated half a pound for every 100 square meters of debris on
the surface, and arrived at 3 million tons of plastic. His estimate, it
turned out, was corroborated by U.S. Navy calculations. It was the
first of many staggering figures he would encounter. And it only
represented visible plastic: an indeterminate amount of larger
fragments get fouled by enough algae and barnacles to sink. In 1998,
Moore returned with a trawling device, such as Sir Alistair Hardy had
employed to sample krill, and found, incredibly, more plastic by weight
than plankton on the ocean’s surface.
In fact, it wasn’t even close: six times as much.
When he sampled near the mouths of Los Angeles
creeks that emptied into the Pacific, the numbers rose by a factor of
100, and kept rising every year. By now he was comparing data with
University of Plymouth marine biologist Richard Thompson. Like
Thompson, what especially shocked him were plastic bags and the
ubiquitous little raw plastic pellets. In India alone, 5,000 processing
plants were producing plastic bags. Kenya was churning out 4,000 tons
of bags a month, with no potential for recycling.
As for the little pellets known as nurdles, 5.5
quadrillion—about 250 billion pounds—were manufactured annually. Not
only was Moore finding them everywhere, but he was unmistakably seeing
the plastic resin bits trapped inside the transparent bodies of
jellyfish and salps, the ocean’s most prolific and widely distributed
filter-feeders. Like seabirds, they’d mistaken brightly colored pellets
for fish eggs, and tan ones for krill. And now God-knows-how-many
quadrillion little pieces more, coated in body-scrub chemicals and
perfectly bite-sized for the little creatures that bigger creatures
eat, were being flushed seaward.
What did this mean for the ocean, the ecosystem,
the future? All this plastic had appeared in barely more than 50 years.
Would its chemical constituents or additives—for instance, colorants
such as metallic copper—concentrate as they ascended the food chain,
and alter evolution? Would it last long enough to enter the fossil
record? Would geologists millions of years hence find Barbie doll parts
embedded in conglomerates formed in seabed depositions? Would they be
intact enough to be pieced together like dinosaur bones? Or would they
decompose first, expelling hydrocarbons that would seep out of a vast
plastic Neptune’s graveyard for eons to come, leaving fossilized
imprints of Barbie and Ken hardened in stone for eons beyond?
Moore and Thompson began consulting materials
experts. Tokyo University geochemist Hideshige Takada, who specialized
in EDCs—endocrine-disrupting chemicals, or “gender benders”—had been on
a gruesome mission to personally research exactly what evils were
leaching from garbage dumps all around Southeast Asia. Now he was
examining plastic pulled from the Sea of Japan and Tokyo Bay. He
reported that in the sea, nurdles and other plastic fragments acted
both as magnets and as sponges for resilient poisons like DDT and PCBs.
The use of aggressively toxic polychlorinated
biphenyls—PCBs—to make plastics more pliable had been banned since
1970; among other hazards, PCBs were known to promote hormonal havoc
such as hermaphroditic fish and polar bears. Like time-release
capsules, pre-1970 plastic flotsam will gradually leak PCBs into the
ocean for centuries. But, as Takada also discovered, free-floating
toxins from all kinds of sources—copy paper, automobile grease, coolant
fluids, old fluorescent tubes, and infamous discharges by General
Electric and Monsanto plants directly into streams and rivers—readily
stick to the surfaces of free-floating plastic.
One study directly correlated ingested plastics
with PCBs in the fat tissue of puffins. The astonishing part was the
amount. Takada and his colleagues found that plastic pellets that the
birds ate concentrate poisons to levels as high as 1 million times
their normal occurrence in seawater.
By 2005, Moore was referring to the gyrating
Pacific dump as 10 million square miles—nearly the size of Africa. It
wasn’t the only one: the planet has six other major tropical oceanic
gyres, all of them swirling with ugly debris. It was as if plastic
exploded upon the world from a tiny seed after World War II and, like
the Big Bang, was still expanding. Even if all production suddenly
ceased, an astounding amount of the astoundingly durable stuff was
already out there. Plastic debris, Moore believed, was now the most
common surface feature of the world’s oceans. How long would it last?
Were there any benign, less-immortal substitutes that civilization
could convert to, lest the world be plastic-wrapped evermore?
That fall, Moore, Thompson, and Takada convened at
a marine plastic summit in Los Angeles with Dr. Anthony Andrady. A
senior research scientist at North Carolina’s Research Triangle,
Andrady is from Sri Lanka, one of South Asia’s rubber-producing powers.
While studying polymer science in graduate school, he was distracted
from a career in rubber by the surging plastics industry. An 800-page
tome he eventually compiled, Plastics in the Environment, won him
acclaim from the industry and environmentalists alike as the oracle on
its subject.
The long-term prognosis for plastic, Andrady told
assembled marine scientists, is exactly that: long-term. It’s no
surprise that plastics have made an enduring mess in the oceans, he
explained. Their elasticity, versatility (they can either sink or
float), near invisibility in water, durability, and superior strength
were exactly why net and fishing line manufacturers had abandoned
natural fibers for synthetics such as nylon and polyethylene. In time,
the former disintegrate; the latter, even when torn and lost, continue
“ghost fishing.” As a result, virtually every marine species, including
whales, is in danger of being snared by great tangles of nylon loose in
the oceans.
Like any hydrocarbon, Andrady said, even plastics
“inevitably must biodegrade, but at such a slow rate that it is of
little practical consequence. They can, however, photodegrade in a
meaningful time frame.”
He explained: When hydrocarbons biodegrade, their
polymer molecules are disassembled into the parts that originally
combined to create them: carbon dioxide and water. When they
photodegrade, ultraviolet solar radiation weakens plastic’s tensile
strength by breaking its long, chain-like polymer molecules into
shorter segments. Since the strength of plastics depends on the length
of their intertwined polymer chains, as the UV rays snap them, the
plastic starts to decompose.
Everyone has seen polyethylene and other plastics
turn yellow and brittle and start to flake in sunlight. Often, plastics
are treated with additives to make them more UV-resistant; other
additives can make them more UV-sensitive. Using the latter for
six-pack rings, Andrady suggested, might save the lives of many sea
creatures.
However, there are two problems. For one, plastic
takes much longer to photodegrade in water. On land, plastic left in
the sun absorbs infrared heat, and is soon much hotter than the
surrounding air. In the ocean, not only does it stay cooled by water,
but fouling algae shield it from sunlight.
The other hitch is that even though a ghost
fishnet made from photodegradable plastic might disintegrate before it
drowns any dolphins, its chemical nature will not change for hundreds,
perhaps thousands of years.
“Plastic is still plastic. The material still
remains a polymer. Polyethylene is not biodegraded in any practical
time scale. There is no mechanism in the marine environment to
biodegrade that long a molecule.” Even if photodegradable nets helped
marine mammals live, he concluded, their powdery residue remains in the
sea, where the filter feeders will find it.
“Except for a small amount that’s been
incinerated,” says Tony Andrady the oracle, “every bit of plastic
manufactured in the world for the last 50 years or so still remains.
It’s somewhere in the environment.”
That half-century’s total production now surpasses
1 billion tons. It includes hundreds of different plastics, with untold
permutations involving added plasticizers, opacifiers, colors, fillers,
strengtheners, and light stabilizers. The longevity of each can vary
enormously. Thus far, none has disappeared. Researchers have attempted
to find out how long it will take polyethylene to biodegrade by
incubating a sample in a live bacteria culture. A year later, less than
1 percent was gone.
“And that’s under the best controlled laboratory
conditions. That’s not what you will find in real life,” says Tony
Andrady. “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 10 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 50 years is too short
a time for evolution to develop the necessary biochemistry.
“But give it 100,000 years,” says Andrady the
optimist. He was in his native Sri Lanka when the Christmas 2004
tsunami hit, and even there, after those apocalyptic waters struck,
people found reason to hope. “I’m sure you’ll find many species of
microbes whose genes will let them do this tremendously advantageous
thing, so that their numbers will grow and prosper. Today’s amount of
plastic will take hundreds of thousands of years to consume, but,
eventually, it will all biodegrade. Lignin is far more complex, and it
biodegrades. It’s just a matter of waiting for evolution to catch up
with the materials we are making.”
And should biologic time run out and some plastics remain, there is always geologic time.
“The upheavals and pressure will change it into
something else. Just like trees buried in bogs a long time ago—the
geologic process, not biodegradation, changed them into oil and coal.
Maybe high concentrations of plastics will turn into something like
that. Eventually, they will change. Change is the hallmark of nature.
Nothing remains the same.”
Copyright ©2007 by Alan Weisman. All rights reserved.
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