B-+plastic+bag+decomposition


 * How long does it take for plastic garbage bags to decompose in a landfill site? **
 * Zoe Stein, 13 October**

- Plastic garbage bags have only been around for 50 years so there is no first-hand evidence of their decomposition rate

- A **Respirometry Test** is a test done to speed up the decomposition rate of things like banana peels and newspapers by adding microbe-rich compost to them in aerated vessels. -The microorganisms then assimilate the sample producing carbon dioxide. - The carbon dioxide level is an indicator of the amount of degradation - The problem with using this test for plastic garbage bags is that no carbon dioxide is found to be produced, meaning they do not undergo decomposition

- Plastic garbage bags, or any plastic bags for that matter, are made of **polyethylene**, a man-made polymer - Microorganisms don’t recognize this as food, so polyethylene is not biodegradable - Polyethylene //is// **photodegradable** though: - With the sun’s ultraviolet radiation, polyethylene’s polymer chains slowly become more and more brittle until they crack into smaller chains - This means the chains will become smaller and smaller and will eventually fragment into microscopic granules - These microscopic granules may be extremely tiny, but they are toxic, polluting waterways, soil, wildlife and drinking water

- The lifespan for polyethylene in plastic bags is not known; - Estimations for its lifespan are varying between 500 and 1000 years, but it is also still predicted that they will never fully decompose - **Biopolymers**- biodegradable polymers that are being studied as a significant replacement for polyethylene

- Polyethylene is the most common form of **polystyrene** - Polystyrene is an inexpensive, colorless, hard plastic that can take any mould when heated - Though polystyrene is recyclable, it takes such a long time to biodegrade that it is more of a form of pollution - Polystyrene is an **aromatic hydrocarbon**, and complete oxidation results in water vapour and carbon dioxide. Every other carbon is attached to a phenyl (benzene) group

**Sources** Aromatic Hydrocarbons. (2007). //Accessscience//. Retrieved October 11, 2010, from [] Lapidos, Juliet. (2010). //Slate//. Retrieved from [] Oxidation Processes. (2007). //Accessscience//. Retrieved October 11, 2010, from [] //Polymers.// (2007). Accessscience. Retrieved October 11, 2010, from __ [] __ //Replacing plastic bags//. (n.d.). Retrieved from []