A story in today's New York Times warns that scientists estimate five or more vast swaths of trash exist in oceans worldwide. Plastic and other human detritus are pervasive throughout the oceans, but gyres, whirl-pooled areas of swirling water currents, bring the trash together in large, floating bunches. The best known of these toxic gyres is the Pacific Garbage Patch, estimated at twice the size of Texas and floating about 1,000 miles off the coast of California.
Old fishing nets, bottle caps, light bulbs and other garbage fill in the patch, but the plastics that make up the majority of ocean trash are particularly damaging. Plastics take an estimated 1,000 years to decompose in a landfill. When exposed to sun and water in the ocean, they appear to decompose at a much faster rate, but actually just break down into tiny "nurdles" and microscopic particles that fish ingest.
Even more troubling are the toxic chemicals such as DDT and PCBs that plastic readily absorbs. When plankton and small fish swallow tiny plastic bits, they ingest the attached chemicals. Smaller marine animals are in turn eaten by larger ones, and the toxic chemicals pile on up the food chain in a process called bioaccumulation. Journalist Marla Cone's 2006 book Silent Snow describes this process in disturbing detail, as it relates to indigenous people living in the Arctic who subsist on high-food-chain animals such as seal. As the "kings" of the food chain we've become, human beings are at risk of absorbing high levels of toxins accumulated by animals living in polluted environments.
Author Alan Weisman's chapter on nurdles in his 2007 book The World Without Us offers a detailed view of the lifespan of plastic.
The positive side of this sobering news is that awareness breeds action. With the Obama administration taking steps to regulate our treatment of the oceans (see yesterday's post), scientists have a better chance of finding an audience for their discoveries and warnings.