How Does Your Plastic Bag Get Into the Ocean?

Even if you're far inland, the trash you discard can end up as plastic pollution at sea.

If you live hundreds of miles away from the coast, it probably never occurs to you that the plastic bag or cup lid that you toss into the gutter might make its way into the Atlantic or the Pacific. But somewhere between 40,000 and 110,000 metric tons of plastic waste generated by Americans ends up in the ocean, according to a groundbreaking study published earlier this year in the journal Science.

It's difficult to pinpoint where all that refuse originates, and researchers think that much or most of it probably comes from the nation's densely-populated coastlines. But there's also evidence that the nation's inland waterways serve as a conduit for plastic to travel thousands of miles into the oceans.

"The ocean is always downstream," explained Nicholas Mallos, a conservation biologist and ocean debris expert for the Washington, DC-based Ocean Conservancy.

When the conservancy has staged cleanup campaigns along inland waterways far from the ocean, they found large amounts of plastic in rivers and lakes, Mallos said. In addition to littering, "We've often seen illegal dumping of trash in rural areas, and that includes a lot of plastic." A 2009 effort by the conservancy found aquatic waste, much of it plastic items, in 45 states and the District of Columbia.

While researchers have documented the vast floating gyres of plastics and other human trash floating in the world's oceans, there's been relatively little attention paid to plastic in rivers, streams and lakes.

"To my knowledge no one has studied particular routes, with the exception of places like L.A. and Baltimore Harbor where there are trash containment measures in place to prevent debris in rivers from entering the ocean," said Kara Lavender Law, an oceanographer who is principal researcher for the Sea Education Association. "But we don't know what fraction of this waste originated close to the coast versus far inland."

The few studies that exist, however, suggest that it may be a huge problem. A 2011 study of two southern California urban rivers found that that every square meter of water contained from 125 to 819 pieces larger than 4.75 millimeters. A 2013 survey of the Meuse River, which flows 575 miles through France, Belgium and the Netherlands to the North Sea, found that it contained 70,000 pieces of plastic per square meter of water, about 500 of which were roughly an inch or bigger in size.

The studies indicate that most of the plastic pollution in rivers consists of microplastics -- tiny fragments that form when big pieces of plastic waste are exposed to sunlight. Microplastic is easily ingested by marine life, both in rivers and eventually in the ocean. A study published in June found that even microscopic zooplankton, which are a food source for ocean animals, are consuming microplastics at an alarming rate.

Besides plastic trash, recent research suggests that lakes and rivers are polluted with an even more insidious form of plastic -- tiny strands of petroleum-based fabrics such as polyester and nylon, some just a fraction of a millimeter in diameter, which are shed by clothing made from synthetic fabrics when it is laundered. Because the fibers are so tiny, they are washed down drains into sewers and slip through filtering systems in wastewater management plants.

Researchers who used fine mesh nets to strain water from Lake Michigan found more than 19,000 strands per square kilometer during a yet-unpublished 2013 study, the Chicago Tribune reported in February. Scientists believe that the fibers are swallowed by fish and other marine animals, and probably become lodged in their bodies, along with toxic chemicals and bacteria that have been absorbed by the fibers.

If there's any positive takeaway in this, it's that you can do something, at least on a personal level, to reduce the amount of plastic that goes into the oceans. "Put trash and recycling where it goes," said Jenna Jambeck, an associate professor of environmental engineering at the University of Georgia. "Use reusable items -- bags, cups and bottles -- to reduce waste generation."

Finally, Jambeck urges people to pick up litter along or in waterways, and log it with a phone app called the Marine Debris Tracker. The data your provide can help scientists to get a better handle on the aquatic trash problem.

Out To Sea

Our oceans have a pollution problem. Over a decade ago, the North Pacific Gyre was discovered harboring untold tons of plastic trash, and quickly became known as the "Great Pacific Garbage Patch." It was a shocking wake-up call to the world which showed that even the most remote corners of the global were not immune to our throw-away culture. There are five main gyres in Earth's oceans. In January, members of the ocean advocacy group 5 Gyres set out to chart the North Atlantic Gyre. They're suspicion: that the world's water was more polluted than anyone knew, and that a "Great Atlantic Garbage Patch" was lurking somewhere between the U.S. Virgin Islands and Bermuda. But no one had ever looked for it before.

First Trawl

No sooner had the first trawling net been raised from the water than the crew's worst fears were confirmed: plastic. The material's pervasiveness struck Stiv Wilson who, as he says, "began the cruise an independent journalist, and ended it a board member of 5 Gyres." "If you look for it, you will find plastic everywhere, in or out of the gyres," Wilson said. "If you go two miles off the coast of San Francisco and trawl you will find it. It's denser in the gyres, but it's everywhere."

Sampling by Hand

Most of the brown gunk in this image is natural. It's sargassum algae, which gives the North Atlantic Gyre its other name: Sargasso Sea. But the white flecks researchers are reaching for are chunks of plastic floating near the surface. Contrary to what many people think, ocean "garbage patches" are really more like thin stews of pollution. All shapes and sizes of plastic trash hang in the water column, sometimes very spread out, sometimes arranged by wind patterns into dense lines that extend to the horizon.

The Big Stuff

During nearly 40 trawls of the North Atlantic Gyre taken throughout the trip, the net never came up empty. "We got plastic every single time," Wilson said. This pile of garbage was hauled out of the water by hand over the course of about 40 minutes. "This was just two people using crappy pool nets to scoop stuff up," Wilson said. "We got 10 percent of all the stuff in the water, maybe."

The Little Stuff

In amongst small-fry lanternfish are blue flecks of plastic, and even a few BB-sized pellets of "nurdles" -- bits of virgin plastic that fell off a freighter or were washed down a river and into the ocean before they were ever made into a product. "As I like to say, 'shit rolls downhill, and at the very bottom of the hill are the oceans,'" Wilson said. Major rivers like the Columbia and the Mississippi can carry huge amounts of plastics into the oceans, where they remain permanently. Once in the open ocean, plastic may be mistaken for food by fish like the lanternfish. Scientists don't know how often this happens, but they worry that chemicals trapped in plastic could leach into animal tissues and begin a slow march up the food web. Sea birds, large ocean predators -- even people -- may be having this stuff for lunch without even knowing it.

Plastic Reef

Along for the ride was Dutch artist Maarten vanden Eynde (left), who is collecting material to build a reef 40 meters long by 10 meters wide (131 x 33 feet) out of plastic removed from the ocean. He was not disappointed. The expedition collected 876 pounds of plastic, some of it from beaches in the Virgin Islands and Bermuda, but mostly from the open ocean. That included what Stiv Wilson called "his favorite piece of plastic" (right) -- a small fleck with the word "from" still visible, looking like a fractured message from whoever discarded it.

A Losing Battle?

Hauling plastic out of the oceans by hand is never going to work. Wilson said that for the time it takes to fill a freighter with junk, several times that much will be dumped into the sea through everyday human activity. "It's growing at an alarming rate," he said, though he admitted that no one's really sure how much plastic is dumped every year, or how much makes its way to the gyres.

What's Next?

Like the name says, the goal of 5 Gyres is to explore all five of Earth's main ocean gyres. So far the North Atlantic and Pacific gyres are the only ones to have been extensively surveyed. But Wilson said that his colleagues have found plastic in the Indian Ocean gyre during a recent preliminary cruise. "The problem is growing at an alarming rate," he said. The only way to stop it is a dramatic reduction of the plastic we use today, especially single-use items like coffe cup lids, grogery bags, and soda straws. "You're not seeing car bumpers out there," Wilson said. "It sounds trite, but really what's needed is a grassroots effort to reduce our addiction to single-use plastics."