How many times have you seen a statement to the effect:
Plastic is designed to last forever, but is only used for a minute.
Zerowasteguy – (no link as I don’t want him to feel important)
Fortunately, there are still some scientists out there doing actual real science, and a recent paper from the Woods Hole Oceanographic Institution has looked at what happens to plastic over time.
But before that, we need to look at what plastic actually is. Essentially, all plastics are hydrocarbons, mainly composed of Hydrogen and Carbon atoms arranged in a variety of ways to make the different types of plastic we use every day.
Out in the environment, oxygen and nitrogen are added and that combination of elements is the basic set that all living things are made from – with a few other trace elements to give some variety of taste.
The basic simple takeaway is that plastics are mainly composed of two common natural elements and thus will break down like anything else in the natural world. The good news is that plastics are thus food for some organisms. While you and I might not find a polystyrene cup very appetising, there are microbes that do.
Back in 2014 researchers were asking questions about the missing 99% of plastic in the ocean. Where was it going and why?
Once the pieces of plastic in the ocean got below 1 mm in size the quantity dropped off significantly and there were almost none below 0.5 mm. Why?
Microbes eat them. The little critters have been nibbling all along but once the surface area to volume ratio is high enough, the critters have won. Scientists have found bacteria that eat PET plastic and fungi in a landfill eating polyurethane. Nature has its ways!
So what did the latest paper show about polystyrene in the ocean?
Not only that the structure of the foam breaks down but the substance of the foam “is completely photo-chemically oxidized to carbon dioxide and partially photo-chemically oxidized to dissolved organic carbon.”
Basically, the hydrocarbon-based plastic simply breaks back down into CO2 and organic carbon dissolved in water. How long does it take? This study estimates time scales of a decade to centuries but this can depend on sun, wind, waves and so on. Interestingly, little bits of the most buoyant of plastics, polystyrene foam, do not seem to be found in the plastics sieved from the ocean.
Archaeologists dig up centuries-old pieces of pottery and glass but it seems that they will not be digging up old plastic from our landfills next millennium.
Obviously this is not licence to throw your plastic trash in the sea this summer or biff it out the car window. There are innovative ways of dealing with our plastic mountain – fence posts for example. Or the plastic could be burnt to make electricity to power all JAG’s electric smug-mobiles. What a pity the Greens are against such a sensible idea.