Where Has All the Plastic Gone?

We live in a society of plastics, no doubt about it. And as our insatiable appetite for plastics has increased year after year, so too has the quantity of plastics flowing into our ocean. The magnitude of this input and the ultimate resting place of ocean plastic pollution, however, remain up for debate.

In a study just published in the Proceedings of the National Academy of Sciences (PNAS), Dr. Andres Cozar and his colleagues estimate the total amount of floating plastic debris in the ocean is several orders of magnitude less than the 1 million tons extrapolated from data published by the National Academy of Sciences in the 1970s.

The question that emerges from this study is one that Dr. Richard Thompson posed in 2004: “Where is all the plastic?”

Just as there are many ways for plastics to enter the ocean, there are also many “sinks” to which plastics can find their way. Cozar notes another probable explanation for the missing plastics is micro-algae attaching to the plastics surface and causing it to sink below the surface, and wind acting on the sea surface can push plastics deep down into the mixed layer.

Another increasingly supported hypothesis is that a sizeable portion of the missing plastics could be inside marine biota—ranging in size from copepods to fishes to sea turtles to marine mammals. The ingestion of these materials is particularly troublesome since plastics adsorb contaminants from the surrounding seawater onto the sea surface, posing a toxicological threat to the organism. This, of course, is in addition to the physical blockage or piercing of animals’ digestive systems. Recently, researchers showed that arctic sea ice could be holding up to 1 trillion pieces of plastics that will become bioavailable as the ice melts over the next decade.

Regardless of where these missing plastics may rest, the solution is simple:  stop these materials from flowing into the marine environment. This means looking to rapidly industrializing nations where increasing populations and affluence are fueling a yearning for the single use disposable plastics that have been a part of our society for decades. Unfortunately, in most of these developing geographies the most basic of waste management infrastructure does not yet exist. Moreover, we must work with the most qualified and sophisticated corporations on this planet to create public-private partnerships to remedy these basic waste management needs.

There’s no single solution to ocean plastics; everyone has a role to play. I encourage everyone to join Ocean Conservancy and be part of the solution with us by participating in the International Coastal Cleanup on September 20.

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