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View Diary: Towards Zero Emissions: The Methane Cycle   (43 comments)

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  •  OK. Explain the chemistry to me ... (1+ / 0-)
    Recommended by:
    dotcommodity

    ...when I was in college, some of the dopier guys on weed or, more dangerously, booze, used to light their farts through their jeans for a quick blast of greenish-yellow flame. I don't know if anybody is still dumb enough to do this except on Jackass, but my question is: does the methane cause more atmospheric trouble in its...er...pristine state, or after it's been torched?

    •  I'm not sure there's a definitive answer (2+ / 0-)
      Recommended by:
      trashablanca, dotcommodity

      I know who to ask, though. I'll get back to you.

      In the meantime, and I'm sure you've seen this, I can give Al Franken's take on the matter:

      From Lies and the Lying Liars Who Tell Them

      I want to draw you a word picture of a lagoon you may remember from Gilligan's Is­land, where a caged lion or an Indian in a canoe might wash up just to get that week's episode rolling. This lagoon is a rectangle the size of three football fields, lined with 40-mil high-density polyethyl­ene and filled, to a depth of thirty feet, with pig shit.

      Now imagine that, at the bottom of the lagoon, pebbles have punctured the liner, allowing the liquefied pig shit to seep under and ferment. A bubble is growing. The polyethylene liner rises like a creature from the brown lagoon. It breaks the surface, spilling a pungent stew of untreated feces and urine into a nearby creek. An undocumented Guatemalan worker is ordered to puncture the liner with a shotgun blast. Retching, he fires. The swollen liner re­treats into the fetid depths. Mission accomplished.

      The next day, however, one of the most magnificent sights in all of nature, a shit geyser, explodes into the afternoon sky. Those working nearby watch the pillar rise ten, then twenty, then thirty feet above the lagoon. It is as though the Earth itself is afflicted with a virulent case of projectile diarrhea.

      Hold that image in your mind.

    •  Don't Know Much About Chemistry (3+ / 0-)
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      trashablanca, A Siegel, chapter1

      One CH4 combusts to one C02 and two H2Os.  

      Over a century, one CO4 is 23 times more "warming" than one CO2.

      CO4 is usually removed from the atmosphere by reaction - OH, hydroxyl, which may be produced when a cosmic ray strikes a molecule of water vapor:
      CH4 + - OH → - CH3 + H2O

      Hydroxyl, - OH reaction in the troposphere cycles CO4 in 9.6 years.  Minor sinks are soil (160 year cycle) and stratospheric loss by reaction with - OH, - Cl and - O1D in the stratosphere (120 year cycle) for an average methan cycle in the atmosphere of 8.4 years.

      Or so says Wikipedia.

      Solar is civil defense. Video of my small scale solar experiments at http://solarray.blogspot.com/2006/03/solar-video.html

      by gmoke on Mon May 07, 2007 at 09:31:54 PM PDT

      [ Parent ]

      •  Actually (0+ / 0-)

        Tropospheric OH comes mostly from photolysis of formaldehyde and HONO in combination with the ozone reaction with alkenes.  The rest of your comment is mostly correct.

        •  Eh??? (0+ / 0-)

          Primary OH source is O1D (from photolysis of ozone) and water.  Formaldehyde (which comes mostly from methane oxidation) may be significant in the upper troposphere.  HONO may be important in high NOx regions near the surface, especially shortly after sunrise. Ozone and alkenes may be important in regions with high ozone and alkene loadings (but it depends on alkene).  All that said, ozone and water is where the bulk of the action is.

          •  It is a source (0+ / 0-)

            but I don't think it is the primary one in the troposphere.  In the stratosphere you are right.  But, tropospheric ozone is actually not the biggest source of tropospheric OH.  The realization of that has been fairly recent.  I think that is the way it is in the latest version of Atmospheric Chemistry by Finlayson-Pitts, and Pitts anyways.

            •  I think you might want to double check (0+ / 0-)

              I'm sure F-P&P (or Seinfeld and Pandis, or Jacob) don't say that!

              •  It takes (0+ / 0-)

                wavelengths below 300 nm to produce 1DO.  That happens a lot in the stratosphere, but ozone protects us down here.  Most ozone photolysis in the lower troposphere is 3PO which is not high enough in energy to abstract hydrogen from water.  It is not that important for this discussion though.  I am sure you will agree that most of it does not come from cosmic rays, unless  you are counting sunlight.

              •  You are right (0+ / 0-)

                In that overall in the atmosphere (1D)O from ozone is the most important source when you include the upper troposphere and stratosphere, and that is what counts for the overall lifetime of methane.

                •  Tell you what (0+ / 0-)

                  Take any surface data set and see for yourself. Even at the surface JO1D is high enough to dominate production for normal amounts of ozone.  HOx is easy even though there are a gazillion reactions because you can assume it's at steady state.  If you need a mechanism just ask. If the UCR in your handle refers to UC Riverside, ask F-P herself.

                  (BTW, the relative contribution of formaldehyde, acetone, and peroxides compared to ozone/water is largest in the UT: it's very dry up there.  Stratosphere is drier, of course, but there's even less in the way of OVOC, peroxides up there)

                  •  Just checked FP+P (0+ / 0-)

                     It says that (1D)O dominates in the remote regions and is important in polluted areas.  I take that to mean it does not dominate there.  I was wrong to omit that reaction as a source of OH.  It is important.  Thanks for the correction.  btw, FP is at UCI now, not UCR and has been there for some time.  I based my statements on comments I heard from a professor at UCR about polluted air and the dominant sources of OH.  Also, an additional source we did not cover is HO2 + NO, a reaction we happen to be doing at the moment and even H2O2 photolysis which we are using to indirectly produce HO2.  Air pollution gets quite complicated doesn't it?

      •  CH4, not CO4 (1+ / 0-)
        Recommended by:
        chapter1

        Mother Nature bats last.

        by pigpaste on Mon May 07, 2007 at 09:50:30 PM PDT

        [ Parent ]

    •  lighting farts through jeans is not dangerous, (2+ / 0-)
      Recommended by:
      BruceMcF, dotcommodity

      ethanol fumes notwithstanding. It's the kind of entertainment, like storytelling and playing the piano, that will become more popular in the future, when low-energy recreation will replace TV, Sunday drives, etc.

      Mother Nature bats last.

      by pigpaste on Mon May 07, 2007 at 10:00:53 PM PDT

      [ Parent ]

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