Ashley Park and Amber Watson, both juniors at Spanish Fort High School in Alabama, sent me an email after reading, "We discover what’s floating in the South Pacific." They wanted to know how trash travels in the ocean and if recycling is really the answer.

Since I’m not a plastic pollution expert, I turned to Marcus Eriksen, the co-founder of 5 Gyres, a non-profit studying garbage in the ocean, to provide some answers. Eriksen has traveled 2,600 miles across the Pacific Ocean on a raft made of 15,000 plastic bottles and regularly speaks at schools and companies across the U.S. about the effects of marine debris.

Left: Ashley Park. Right: Amber Watson, both juniors at Spanish Fort High School in Alabama.

Ashley Park & Amber Watson: What was the plastic pollution rate ten years ago? Has the rate decreased since then?

Marcus Eriksen: We're not seeing significant increases in plastic density in the North Atlantic.  Check out the work of Sea Education in the Journal of Science, where they compared 22 years of sampling the [North Atlantic] gyre.; We know there's more plastic going in [and] we think it's washing up on islands, the natural nets in the gyres: as the gyres accumulate and circulate floating debris, much of it washes ashore on islands in their path. If we turn off the tap of plastic pollution to the ocean, the gyres will rid themselves of plastic.

AP & AW: What is the condition of plastics in the ocean now?

ME: It degrades into small particles, which are more easily consumed by foragers and filter feeders. Over time, most plastic pollution will wash ashore, which is where cleanup is most practical.

AP & AW: What are the biggest threats caused by plastic pollution?

ME: Plastics absorb and release toxins, like PCBs, DDT and other hydrocarbons, into the organisms that consume them. Entanglement is also a huge issue, affecting marine mammals, seabirds, fish and turtles worldwide.

AP & AW: Is plastic being recycled more frequently and being reused more efficiently?

ME:Overall, no. For some plastics, like PET, yes. To recycle plastic efficiently it must be collected, sorted and sometimes washed before it can be remanufactured. Most products made of plastic today come from virgin petroleum, not recycled plastic.If you contact your local waste recovery center, you'll get the facts about your trash.

In most communities across the United States, plastic water bottles, soda bottles, milk jugs and detergent bottles are selected from the waste stream for recycling because they are high value plastics. The rest is either burned, buried or exported. It all comes down to economics.  For many towns and cities, it's easier to send a ton of plastic to China than to the local landfill.

Right and Below: Trash along the shore of the Azores, photo courtesy of 5 Gyres

AP & AW: Do you feel that recycling plastic would help with plastic pollution in the oceans?

ME: Sure, but the problem is recovering the waste in the world.  The best solution is not to use so much plastic for disposable products in the first place.

AP & AW: Is plastic pollution accumulating in the five major oceanic gyres?

ME: Yes. Check out for our recent observations in the five gyres.

AP & AW: Knowing that some plastics float and others sink, and that ocean waters move, how is plastic pollution distributed around the world vertically, horizontally and seasonally?

ME: Great question.  PE and HDPE float, so they are in all five gyres. PET, PVC, Polycarbonate and Polystyrene all sink, and are found in the nearshore environment, like in the sediments of river mouths.  The smallest particles can become neutrally buoyant simply by their size. Neutrally buoyant means that the particle neither sinks nor floats, it just hovers in the water column.

We find plastic throughout the water column. There is a need for new scientists to figure out the mechanisms for vertical transport, the distribution around the world and the temporal change. Maybe this could be you?

Left: A mass of tangled rope and fishing line in the North Pacific Gyre; by Lindsey Hoshaw

AP & AW: Knowing that plastic pollution photodegrades, chemically degrades, and mechanically breaks into smaller fragments, where do the smallest particles eventually go?

ME: The fate of plastic is an unanswered question. Islands are the natural nets for floating debris. Small particles may sink as they absorb POPs [persistent organic pollutants, like PCBs and DDT], or they are ingested and excreted as heavy fecal pellets, before sinking.  The fate of microplastics is unknown.

AP & AW: Knowing that plastic pollution can be a sponge for many hydrophobic pollutants, do these pollutants desorb and bioaccumulate inside fish that ingest the pollution?

ME: Yes, our colleague Chelsea Rochman is studying this using fish we collected in the South Atlantic Gyre. She has shown in the lab that fish can bioaccumulate POPs from ingested plastic. We don't know if it happens in the field [or how it affects humans that eat animals that have ingested POPs].

Thank you Ashley and Amber for your questions!

For more information about plastic in the ocean, you can also check out these organizations:

The Algalita Marine Research Foundation

Scripps Institution of Oceanography

Woods Hole Oceanographic Institute

The National Oceanic and Atmospheric Administration


About the Author: Lindsey Hoshaw is a freelance environmental journalist. Her work has appeared in The New York Times, the Boston Globe and Forbes, among others. In her spare time she moonlights as a garbologist studying people and the things they throw away. Follow her on Twitter @thegarbagegirl.

Editor’s note: The South Pacific Islands Survey is part of a larger multiyear expedition run by Pangaea Exploration, a nonprofit that investigates the health of marine life through exploration, conservation and educational outreach. The expedition focuses on marine debris, water quality, habitat conditions and overfishing in the world’s oceans. Specific emphasis is placed on the five gyres, or the five areas with the highest accumulation of plastic pollution.

The views expressed are those of the author and are not necessarily those of Scientific American.