Turkey Day eco-mysteries, solved.

But if you insist on wrapping your leftovers in foil, you can reduce its impact by reusing it. Using one piece of foil three times requires about as much fossil fuel as using three pieces of plastic wrap and is less toxic to ocean life. You'd have to use that foil six times, however, before starting to break even with single-use plastic on greenhouse gas emissions and human health impacts. (You can find out more about these comparisons—and about recycled aluminum—in this column from April.)

I'm inevitably going to get rid of some food at the end of this week's debauchery. If I don't have a composter, am I better off feeding my leftover sweet potatoes to the garbage disposal or the trash can?

Tossing food down your disposal can eventually add excess nutrients to rivers and streams, changing their chemical composition and potentially harming aquatic life. If you opt for the disposal, you'll also be using a lot more water than if you chucked your waste in the trash bin—and you'll be indirectly responsible for all the metal-mining and manufacturing needed to make the appliance.

On the other hand, trucking all that garbage from your curb to a landfill uses a lot of energy. And when your trash decomposes, it will likely release more damaging greenhouse gases—namely, methane.

Composting is always best, but if that's not an option, the Lantern advised that you go ahead and use your garbage disposal under the following conditions: First, make sure that your community isn't running low on water. (To check your local status, click  here.) Second, don't put any grease or fat in the disposal. And finally, find out whether your local water-treatment plant captures methane and uses it to produce energy. If it doesn't—and your local landfill does—you may be better off tossing those mashed potatoes in the trash. (For a more detailed analysis of the disposal-landfill showdown, check out this column from 2008.)

Is there an environmental quandary that's been keeping you up at night? Send it to  ask.the.lantern@gmail.com, and check this space every Tuesday.

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