why does plastic take so long to decompose

Most plastic is manufactured from petroleum the end product of of once-living organisms. Petroleum's main components come from lipids that were first assembled long ago in those organisms' cells. So the question is, if petroleum-derived plastic comes from biomaterial, why doesn't it biodegrade? A crucial manufacturing step turns petroleum into a material unrecognized by the organisms that normally break organic matter down. Most plastics are derived from propylene, a simple chemical component of petroleum. When heated up in the presence of a catalyst, individual chemical units monomers of propylene link together by forming extremely strong carbon-carbon bonds with each other. This results in polymers long chains of monomers called polypropylene. "Nature doesn't make things like that," said Kenneth Peters, an organic geochemist at Stanford University, "so organisms have never seen that before. "
The organisms that decompose organic matter the ones that start turning your apple brown the instant you cut it open "have evolved over billions of years to attack certain types of bonds that are common in nature," Peters told Life's Little Mysteries. "For example, they can polysaccharides to get sugar. They can chew up wood. But they see a polypropylene with all its carbon-carbon bonds, and they don't normally break something like that down so there aren't metabolic pathways to do it," he said. But if all you have to do to make propylene subunits turn into polypropylene is heat them up, why doesn't nature ever build polypropylene molecules? According to Peters, it's because the carbon-carbon bonds in polypropylene require too much energy to make, so nature chooses other alternatives for holding together large molecules. "It's easier for organisms to synthesize peptide bonds than carbon-carbon bonds," he said.


Peptide bonds, which link carbon to nitrogen, are found in proteins and many other organic molecules. Environmentalists might wonder why plastic manufacturers don't use peptide bonds to build polymers rather than carbon-carbon bonds, so that they'll biodegrade rather than lasting forever. Unfortunately, while peptide bonds would produce plastics that biodegrade, they would also have a very short shelf life. "It's an issue of 'you can't have your cake and eat it too,'" said Jim Coleman, chief scientist at the US Geological Survey Energy Resources Program. "When you buy a plastic jar of mayonnaise, you want [the jar] to last a few months. " You don't want it to start decomposing before you've finished the mayo inside. Peters explained that some disposable plastic products which don't need a very long shelf life are synthesized with peptide bonds in their chemical composition. "But a carbon-carbon linkage will be more stable, so it depends on what people are trying to make. " Got a question? This e-mail address is being protected from spambots. You need javascript enabled to view it This e-mail address is being protected from spambots. You need javascript enabled to view it This e-mail address is being protected from spambots. You need javascript enabled to view it This e-mail address is being protected from spambots. You need javascript enabled to view it This e-mail address is being protected from spambots. You need javascript enabled to view it This e-mail address is being protected from spambots. You need javascript enabled to view it This e-mail address is being protected from spambots. You need javascript enabled to view it This e-mail address is being protected from spambots. You need javascript enabled to view it This e-mail address is being protected from spambots.


You need javascript enabled to view it This e-mail address is being protected from spambots. You need javascript enabled to view it and we'll crack it This e-mail address is being protected from spambots. You need javascript enabled to view it. Follow Natalie Wolchover on Twitter @ How long Does it really take plastic to decompose?! For 20 years I have avoided this question because I knew the answer would destroy my favourite post kayaking tradition - eating 100lbs of hand cut fries covered in squeeky Quebec cheese curds and smothered in thick, dark gravy. б If youБre not familiar, this French Canadian delicacy is known as Poutine. And itБs amazing. And the absolute best Poutine is found at roadside chip trucks that serve said poutine in a plastic styrofoam container, with a plastic lid, in a plastic bag with a plastic fork and disposable napkin. And when youБve spent the 5 whole minutes it takes to eat this God given treat, the container, lid, bag and fork end up in an overflowing garbage can where it will be trucked to a landfill б - not a recycling plant - and sit and sit and sit for 100 years, 1,000 yearsБ forever? So you can understand why I didnБt really want to know how long it takes plastic to biodegrade because the truth would render this joyful activity a little less so - until. I couldnБt really avoid it (check out for more on my БawakeningБ). But I figured if I could face the truth about plastic, you could too. And hereБs the thing - decomposition, compostability, biodegradability - is largely dependent on microbes, tiny organisms that are invisible to the naked eye. б Despite their teenie size, these guys play an enormous role in cleaning up our planet, but because plastic is made up of compounds that donБt naturally occur in nature, microbes turn their nose up at plastic,. б б Plastic does not decompose. ever!


Which means, according to, plastic does not decompose, biodegrade or compost, rather it just breaks down into smaller and smaller plastic pieces. "Plastics don't biodegrade like organic matter, which means they can't be converted by living organisms into useful compounds for life. Instead, they photodegrade, a process by which photons from the sun's rays pulverize the plastic polymers until they are broken into individual molecules. " (, clogging our landfills and even leaching toxins into our water table. Great, so microbes canБt eat plastic, therefore plastic is bad, right? Ish. б Ish you say? б WhatБs this ishБ please explain. б Well, you see, plasticБs inability to biodegrade is definitely problematic, but just refers to everything from the steering wheel of your car to the grocery bag you used to drag home those delicious organic berries (and that 10 pound sack of cheesies). In fact, some would argue that the plastic used in car manufacturing actually provides a net benefit to the environment because it is lighter than steel and makes cars more fuel efficient and therefore burns less fossil fuels. Grocery bags, plastic wrap, sandwich bags, ziplock bags and produce bags are more troubling because they are typically used once - maybe twice - and then discarded, where - as previously established - they will wind up in a landfill or somewhere out in the wilderness where they will never biodegrade. б And this begs the question that we - the consumers - must face. б Is the ease of use of plastics like grocery bags, styrofoam containers or disposable forks really worth the cost? б Now you know that those single use plastics cannot decompose, what are you going to do about it?

  • Views: 5

why does the us import and export oil
why does my dog have a rash on his belly
why does methanol have a low boiling point
why does matter need to be recycled
why does lemon juice turn brown when heated