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.