SEA OF TRASH

Not even oceanographers can tell us exactly how much floating scruff is out there; oceanographic research is simply too expensive and the ocean too varied and vast. In 2002, Nature magazine reported that during the 1990s, debris in the waters near Britain doubled; in the Southern Ocean encircling Antarctica the increase was a hundredfold. And depending on where they sample, oceanographers have found that between 60 and 95 percent of today’s marine debris is made of plastic.

Plastic gets into the ocean when people throw it from ships or leave it in the path of an incoming tide, but also when rivers carry it there, or when sewage systems and storm drains overflow. Despite the Ocean Dumping Reform Act, the US still releases more than 850 billion gallons of untreated sewage and storm runoff every year, according to a 2004 EPA report. Comb the Manhattan waterfront and you will find, along with the usual windrows of cups, bottles and plastic bags, what the EPA calls “floatables”, those “visible buoyant or semibuoyant solids” that people flush into the waste stream like cotton swabs, condoms, tampon applicators and dental floss.

The Encyclopedia of Coastal Processes predicts that plastic pollution “will incrementally increase through the 21st century” because “the problems created are chronic and potentially global, rather than acute and local or regional as many would contemplate”. The problems are chronic because, unlike the marine debris of centuries past, commercial plastics do not biodegrade in seawater. Instead, they persist, accumulating over time, much as certain emissions accumulate in the atmosphere. The problems are global because the sources of plastic pollution are far-flung but also because, like emissions riding the winds, pollutants at sea can travel.

In 2001 a peer-reviewed scientific journal called The Marine Pollution Bulletin published a study, whose undramatic title, “A Comparison of Plastic and Plankton in the North Pacific Central Gyre,” belied its dramatic findings. The lead author—a sailor, environmentalist, organic farmer, self-trained oceanographer and onetime furniture repairman named Charles Moore—went trawling in the North Pacific convergence zone about 800 miles west of San Francisco and found seven times as much plastic per square kilometer as any previous study.

“As I gazed from the deck at the surface of what ought to have been a pristine ocean,” Moore later wrote in an essay for Natural History, “I was confronted, as far as the eye could see, with the sight of plastic. It seemed unbelievable, but I never found a clear spot.” An oceanographic colleague of Moore’s dubbed this floating junk yard “the Great Pacific Garbage Patch,” and despite Moore’s efforts to suggest different metaphors—”swirling sewer”, “superhighway of trash”—”Garbage Patch” appears to have stuck.

The Garbage Patch wasn’t merely a cosmetic problem, nor merely a symbolic one, Moore contended. For one thing, it was a threat to wildlife. Scientists estimate that every year at least a million seabirds and 100,000 marine mammals and sea turtles die when they entangle themselves in debris or ingest it. Plastic polymers, as has long been known, absorb hydrophobic chemicals, including persistent organic pollutants, or POPS, like dioxin, PCBs and DDT. Highly controlled in the US but less so elsewhere, such substances are surprisingly abundant at the ocean’s surface.

By concentrating these free-floating contaminants, Moore worried, particles of plastic could become “poison pills”. He also worried about toxins in the plastic itself—phthalates, organotins—that have been known to leach out over time. Once fish or plankton ingest these pills, Moore speculated, poisons both in and on the plastic would enter the food web. And since such toxins concentrate, or “bioaccumulate,” in fatty tissues as they move up the chain of predation—so that the “contaminant burden” of a swordfish is greater than a mackerel’s and a mackerel’s greater than a shrimp’s— this plastic could be poisoning people too.

In the scientific community, Moore’s work is somewhat controversial. Even marine biologists who share his alarm have misgivings about the sensationalism around the Garbage Patch. Since the plastic debris in the North Pacific convergence zone is spread out unevenly across millions of miles of ocean, and since most of it is fragmentary, flowing through the water column like dust through air, the Garbage Patch bears little resemblance to a floating junkyard. But it is, numerous scientists assure, very much for real.
-DONOVAN HOHN (New York Times)