Polymers Are Forever

From: The World Without Us, by Alan Weisman (2007)

The World Without Us assumes that humans have become extinct and discusses how long it will take for nature to heal. Here is a summary of part of the chapter on plastics which I thought you might find interesting.

The North Pacific Subtropical Gyre (oceanographers call it the Great Pacific Garbage Patch) is a mid-ocean sump where nearly everything that blows into the water from half the Pacific Rim eventually ends up, spiraling slowly towards a widening horror of industrial excretion, 90% of it plastic. As of 2005, the North Pacific Gyre was nearly the size of Africa!

In 1975, the U.S. National Academy of Sciences estimated that all oceangoing vessels together dumped 8 million pounds of plastic annually. More recent research showed the world’s merchant fleet alone shamelessly tossing around 639,000 plastic containers every day. But l this is nothing compared to what was pouring from the shore. Nearly 80% of the flotsam had originally been discarded on land. Researchers calculated half a pound for every 100 square meters of debris on the surface of the water and concluded that there were 3 million tons of plastic in the gyre. There is more plastic by weight than plankton on the ocean’s surface—six times as much.

But this is only what is on the surface.

Using a trawler-type device, researchers have found little plastic pellets, plastic resin bits, called nurdles. We produce about 5.5 quadrillions of them—250 billion pounds—a year. Not only are they found everywhere in our environment, they are especially ubiquitous in the ocean. They are being found inside the transparent bodies of jellyfish and salps, the ocean’s most prolific and widely distributed filter-feeders. Like seabirds, they’d mistaken the brightly colored pellets for fish eggs, and tan ones for krill. In the sea, nurdles and other plastic fragments act both as magnets and as sponges for resilient poisons like DDT and PCB’s. Puffins, for example, eat these pellets or eat fish that have eaten other fish which have eaten the pellets, and they concentrate poisons to levels as high as one million times their normal occurrence in seawater.

There are six other major tropical oceanic gyres, all filled with swirling debris. It’s as if plastic exploded upon the world from a tiny seed after World War II and, like the Big Bang, is still expanding. Even if production stops immediately, an astounding amount of the astoundingly durable stuff is already out there. Plastic debris was now the most common surface of the world’s oceans.

How long will it last? For a long time. Like any hydrocarbon, even plastics inevitably must biodegrade, but at such a slow rate that is of little practical consequence. Plastics, however, can photodegrade much sooner. When they do so, ultraviolet solar radiation weakens plastic’s tensile strength by breaking its long, chain-like polymer molecules into shorter segments and it starts to decompose into smaller pieces. How long this will take is unknown. Plastic has only been around for about 55 years, not long enough for any of it to decompose, either on land or on sea yet.

As it decomposes, its powdery residue remains in the sea, where the filter feeders will find it in put its poisons into the global food chain. The rest will settle into the seabeds, where it may never disintegrate because of the lack of oxygen and heat.

Paper or plastic anyone?