non degradable plastics: buried vs burnt vs floating?

Take an average plastic water bottle thrown away by the millions everyday. In developing countries they’re not generally recycled, but either buried, chucked in the sea or swept up into massive piles then burnt.

which is worse for the environment and how long is their history in each case before they break down into something that natural organisms can make use of? does that ever happen?

note to add, I’m particularly interested in what happens when burning plastics vs the other two options. My google searches on this haven’t really found hard info, in my travels through south east asia, India etc I’ve observed the massive piles of burning plastics from the water bottles that tourists drink many times…

In the west our assumption is that must be bad, but is it worse than burying and forgetting or floating in terms of the long term cycle of the plastics?

Hopefully some more knowledgeable posters will come along shortly, but burning plastics releases some volatile hydrocarbons - I’m not cognizant of the details, but I would imagine that in order of negatives:

burning > floating > burying

Burning might be the worst - breathing in that crap is not likely to be good for you.

Yeah I’m curious about this too. I’m not much of an enviornmentalist but plastics and, especially, bags have always bothered me. Southern California Harbors are just flooded with stray bags. I end up catching multiple bags at some of my fishing spots.

The question is really too vague to be answered. Bad in what respect? What type ofplastic?

Buried plastics never decay, but then neither does buried paper. On the bright side that makes it carbon neutral. Being buried it’s also doing no environmental harm either.

Floating plastics in sunlight will break down into small pieces over a period of months or years depending on the type of plastic. In the meantime they may cause some environmental problems, and are certainly unsightly. The small pieces themselves may cause problems, or they may sink to the bottom and be mineralised by microbes depending on the type of plastic. Mineralistaion releases the carbon into the air

Burning at normal temperatures also releases all the carbon into the atmosphere. It also releases a lot of particulates or soot. Depending on the type of plastic it may also release various toxic materials.

ok so lets narrow it down to PET:

huge mounds of the water bottles made from this are burnt all over developing countries. Whats the results of that in the short term local environment and longer term? How much carbon emissions is 1000 1 liter plastic bottle going to be?

what are the potential negatives from burying them? Is it true to say they NEVER decay? what not after 10,000 years? not 1,000,000 years?

Burning releases some toxic nasties, but other than that isn’t all that bad when compared to gasoline usage.

Plastics in the sea can cause harm to various sea life. When it breaks down into particulates, small zooplankton and the like will mistake it for algae and eat it. Not a great thing.

Burying plastic is pretty much benign. Its not going to decompose, but its not going to really hurt anything either. It will just sit there. Wasteful perhaps, but not really harmful.

Some of the nasties will be small hydrocarbons that are considerably larger greenhouse gases than CO2. Unlike with gasoline, they aren’t getting energy out of the deal. They are just putting more CO2 into the atmosphere for no reason at all.

I’m not debating the point, why is it bad if planckton eat it? I would have thought that breaking these things down would be a good thing. I am aware that plastic causes harm to larger sea creatures.

I agree, this is the best way to eliminate non-recycled plastic. It also serves as a miniscule carbon sink. Heck, in a few million years you could have oil or possibly coal again.

I wouldn’t put so much emphasis on carbon as a “pollutant” when burning plastics release dioxins. Any toxic chemical that accumulates in your tissues almost indefinitely seems worse than a little carbon - a whole town in the US was closed and turned into a superfund cleanup site because of dioxins in the oil they would use to keep dust down on their streets.

One of the advantages of burying plastic is that you always have the option to dig it back up later and recycle it. I’ve long held the belief that our old landfills will be seen as treasure troves some day when it becomes cost effective to dig up and re-sort everything. (Unfortunately, we all too often build golf courses and houses on top).

No doubt dioxins are bad, but I highly doubt that a large fraction of the plastics they are burning are halogenated. Mostly it will be PET, styrene and polyethylene. Spraying a street with halogenated oil is just stupid.

Burning could either be really bad or really good, depending on how it’s done. At normal temperatures (i.e. a big open fire), burning will release all sorts of unpleasant particulates and hydrocarbons and greenhouse gases. However, if you use a proper incinerator, you can take those same plastics and burn them until they’re nothing but CO2 with a few other trace compounds that aren’t so bad. That releases greenhouse gases, for sure, but I think it’s possible to run such an incinerator so that you can extract useful energy and heat as well. In which case it’s no worse that burning oil or coal, plus you’re not adding to the landfill as much.

ETA: I’m not sure what would happen to the halogen atoms after incinerating, but they wouldn’t be in anything so complex and toxic as a dioxin.

Also, standard waste incinerators these days require fuel to get as hot as they do. There are prototypes out there that don’t require additional fuel and also co-generate electricity and heat for other uses.

Plankton’s not usually the problem re: plastics. Larger marine critters such as albatross and sea turtles have major problems when they ingest plastic, often mistaking it for planktonic creatures (such as sea jellies.) I’m not sure how to quantify the problem of zooplankton themselves eating tiny plastic granules, or how much of a problem it might be.

You’re right, unless they’re burning chlorinated plastics like PVC, dioxin isn’t going to be a product.

Why not? You get measurable amounts of dioxin and other chlorinated products from incinerators:

IIRC, over 1000 degrees (can’t recall if that’s C or F,) you can be pretty assured of breaking down the dioxins, but lower temps than that will allow for their production.

I imagine it would be somewhat similar without looking in to it yet - presumably some of the stuff in smoke from PET plastics shouldn’t be breathed in, just as you don’t want to unnecessarily breathe in gasoline fumes. Does anyone have any idea what specifically you would get that you don’t want to breathe in?