August 20, 2009
Ocean Plastics Break Down Faster Than Expected
Some types of plastics break down faster than previously thought.
Contrary to the commonly held belief that plastic takes 500 to 1,000 years to decompose, researchers now report that some types of plastic begin to break down in the ocean within one year, releasing potentially toxic bisphenol A (BPA) and other chemicals into the water.
“Plastics in daily use are generally assumed to be quite stable,” chemist Katsuhiko Saido of Nihon University in Japan said in a press release. “We found that plastic in the ocean actually decomposes as it is exposed to the rain and sun and other environmental conditions, giving rise to yet another source of global contamination that will continue into the future.” Saido presented the work Wednesday at the American Chemical Society meeting in Washington, D.C.
Alan Weisman's book The World Without Us has a section in it that'll give you a deeper appreciation for the scale of the ocean plastic pollution problem. If some of the plastics break down more rapidly releasing toxic chemicals then we have an even bigger problem with them.
But are there actual measurements of the levels of these chemicals in the ocean? I'm just somewhat skeptical of the long-term stability of random organic compounds (especially non-chloro, non-fluoro carbons) in the ocean environment. It's a soup of metal and halogen ions, together with some dissolved oxygen, and also churning and ultraviolet exposure at the surface. Not to mention all the microorganisms. I'd expect most molecules that are CxHxOx (and you can include S, N, and P for that matter, but bisphenol A is just carbon hydrogen and oxygen) to be transformed into CO2, H2O, and/or various salts, in the geologic blink of an eye.
I guess the point is - I very readily believe that plastics break down more rapidly than previously thought, but we also want to know how rapidly the breakdown products themselves break down.
I still don't get the relevance of what happens to the old plastic if no humans are still alive.
Isn't this rich? First plastics were bad because they supposedly didn't decompose, meaning the dolphins would be strangled by thousand-year old nets. Now it turns out plastics do decompose, meaning there is no long-term problem of floating garbage accumulation - but it's still bad, since the homeopathic levels of mildly unpleasant chemicals released in this way seem to bother the conscience of the environmentalist.
Humans are such a plague on the planet, they can't ever do well, can't they?
Thankfully, there are no naturally occurring toxic chemicals added to the ocean that dwarf by a factor of a million human added chemicals.
Ha ha ha.
Yeah, remember that once upon a time oxygen was a toxic chemical that destroyed almost all the life in the oceans. Environmentalists sometimes seem to want to bring about a stasis that is the antithesis of the real world.
A geological blink of the eye is much longer than a human life span.
We know these things do not break down instantly because one can go out into the middle of the Pacific Ocean and find lots of plastics under the surface.
The bigger problem isn't the plastics you can see. Plastics break into smaller pieces due to waves pounding. One of the concerns is that they get taken up by microscopic organisms and displace digestible organic materials in their digestive machinery.
I do not think they are saying all types of plastics break down.
If plastic lasts tens of thousands of years it also lasts decades and centuries.
"We know these things do not break down instantly because one can go out into the middle of the Pacific Ocean and find lots of plastics under the surface."
What, do you want to live in an SF novel?
"One of the concerns is that they get taken up by microscopic organisms and displace digestible organic materials in their digestive machinery."
Because, you know, organisms never naturally encounter any materials they can't digest, and so don't have any mechanisms for expelling them.
I remember reading that book (Mutant 59) when I was a kid. It came to mind when I saw this topic. I'm glad someone else remembered it.
If people keep dumping plastic into the environment, eventually things will evolve to eat it. I suspect microorganisms will start with the short oligomers and work there way back to longer chain polymers. This might even be a good way to artificially evolve such organisms, starting them on a diet of dimers, trimers, etc.