Talk:Methane: Difference between revisions

== High boiling point ==

Why does methane have a higher boiling point than oxygen or nitrogen, even though it is not polar and half as massive? This is not even mentioned in the article. <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/85.232.196.151|85.232.196.151]] ([[User talk:85.232.196.151|talk]]) 12:22, 21 August 2009 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->

* I'm not sure if this is a reason, but although methane has total [[electric dipole moment|dipole moment]]=0, its C-H bonds do have a small polarity (about 3%). N-N and O-O bonds in their molecules are totaly neutral. Perhaps this fact plays a role...

--[[User:Vchorozopoulos|Vchorozopoulos]] ([[User talk:Vchorozopoulos|talk]]) 20:32, 22 October 2009 (UTC)

:As both (di)oxygen and nitrogen have a double bond and p-orbitals, you may suppose their outer surface is slightly more electronegative than the s-based methane, hence more repulsion. If you start into this kind of info, the article is going to be very interesting, but very long.--[[User:Environnement2100|Environnement2100]] ([[User talk:Environnement2100|talk]]) 22:29, 22 October 2009 (UTC)

::Except dioxygen does ''not'' have a double bond in its ground state. [[User:DMacks|DMacks]] ([[User talk:DMacks|talk]]) 02:00, 23 October 2009 (UTC)

N₂, O₂ and CH₄ are all non-polar molecules. The only forces holding these molecules together and keeping them liquid are [[London dispersion force]]s. These forces are stronger between molecules that are more [[Polarizability|polarizable]] - so the reason that CH₄ remains at liquid at temperatures where N₂ and O₂ are gases is that methane is more polarisable than dinitrogen or dioxygen.

[[User:Benjah-bmm27|Ben]] ([[User talk:Benjah-bmm27|talk]]) 22:26, 22 October 2009 (UTC)

* I think the article is a needed that kind of info and not only. It doesn't matter if it'll become large. Someone may need or simply want it. That's why we are here: To provide any correct info we have and explain everything if possible.

--[[User:Vchorozopoulos|Vchorozopoulos]] ([[User talk:Vchorozopoulos|talk]]) 22:34, 28 October 2009 (UTC)

== Net lifetime ==

In the "Atmospheric methane" section there are two statements of "net lifetime" in the atmosphere:

"It has a net lifetime of about 10 years"

"a net lifetime of 8.4 years"

Which is it? Granted, 8.4 is approximately 10 but why use two different values?

Can anyone clarify, and make these consistent? <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/68.145.215.129|68.145.215.129]] ([[User talk:68.145.215.129|talk]]) 03:14, 29 November 2013 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->

:The different estimates are now covered in [[Atmospheric methane#Mean lifespan]]. -- [[User:Beland|Beland]] ([[User talk:Beland|talk]]) 07:17, 21 June 2024 (UTC)

== Methane rocket fuel can be manufactured on Mars ==

In the section on liquid methane rocket fuel there is a statement about NASA's Curiosity rover not finding any methane in the atmosphere of Mars. This statement is misleading because NASA is looking for methane on Mars as a possible biosignature of life, not as a source of fuel. Methane can be produced on Mars using carbon dioxide from the atmosphere and a small amount of hydrogen that is either brought to Mars or extracted from water sources found on Mars. The misleading statement cites an article at:

http://www.nasa.gov/mission_pages/msl/news/msl20130919.html

It should be noted that if you search the article neither the word "rocket" or the word "fuel" are present anywhere. Furthermore, Wikipedia's entry on methane already contains a section on extraterrestrial methane that covers Mars extensively. That section covers the fact that Curiosity found less than 5ppb of methane in the atmosphere and gives four different citations of that fact.

The misleading statement adds no information to the methane article and could be detrimental to readers' understanding of Mars exploration.

Why do people keep undoing my removal of this statement? <small><span class="autosigned">—&nbsp;Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[User:Scott247|Scott247]] ([[User talk:Scott247|talk]] • [[Special:Contributions/Scott247|contribs]]) 18:30, 2 July 2014 (UTC)</span></small><!-- Template:Unsigned --> <!--Autosigned by SineBot-->

:The context in the previous few sentences clearly talks about harvesting already-present methane for fuel purposes, and evidence that it does not seem to exist (in sufficient amount) is a pretty good counterpoint to that idea. Data don't care ''why'' you were originally making the measurements. The statement could be modified to include those details ("NASA's whatever-probe, looking for the methane signature of life, found only 5 ppb[that-cite], which is well below the whatever-amount that would be viable for harvesting as fuel[some-other-cite]."). Your proposal for ''manufacturing'' methane from other present materials is a different idea...one that could also be stated, with cites supporting both the process and the availability of sufficient starting materials. [[User:DMacks|DMacks]] ([[User talk:DMacks|talk]]) 19:12, 2 July 2014 (UTC)

<br>

Yes, the previous few sentences talk about harvesting. Then a misleading statement follows which cites an article that does NOT talk about harvesting. This isn't about the data, this is about intention. The citation and data do not provide evidence that anyone intended to harvest methane on Mars. It's like stating that humans need water to live and then citing a study that found the oceans are undrinkable because they contain salt. The positioning of the statement carries the implication that people were planning to drink ocean water.

[[User:Scott247|Scott247]] ([[User talk:Scott247|talk]]) 19:41, 2 July 2014 (UTC)

:To carry your analogy further, would a sentence like "the existing oceans, containing the vast majority of the water present, are undrinkable because they are salty, but fresh water is available from other sources" be reasonable? It seems like it addresses both ideas: if the topic is specifically ''fresh'' (drinkable) water, it's notable that the most obvious source of "water" is not of this type but that we do have a niche for survival via alternate sources. [[User:DMacks|DMacks]] ([[User talk:DMacks|talk]]) 19:53, 2 July 2014 (UTC)

I'm not trying to add statements to the article, I'm trying to remove one that's poorly positioned. There are equivalent statements in the Extraterrestrial methane section of the article and an explanation of methane production is already given in the Production section of the article. Are you suggesting that I should be elaborating on a redundant statement?

[[User:Scott247|Scott247]] ([[User talk:Scott247|talk]]) 20:43, 2 July 2014 (UTC)

==Assessment comment==

{{Substituted comment|length=2507|lastedit=20070508114532|comment=I have significant misgivings about the CH4 figures given in the table attributed to Houweling et al. (1999).

From reading papers such as

Nature 439, 187-191 (12 January 2006) {{!}} doi:10.1038/nature04420

Methane emissions from terrestrial plants under aerobic conditions

Frank Keppler1, John T. G. Hamilton2, Marc Bra1,3 and Thomas Röckmann1,3

This information on CH4 emissions is potentially grossly understated as plant matter is not listed as a source of methane emissions to the atmosphere. The authors reach a conclusion that CH4 emmissions of 62–236 Tg yr-1 for living plants and 1–7 Tg yr-1 for plant litter. The range forliving plants is large but even at the lower end of the range it indicates that there is a significant CH4 contribution from living plants that has not been taken into account in Houweling et al (1999).

Similarly the estimate and comment that livestock contribute 35% of the Anthropogenic Emissions may well be a considerable exaggeration of their contribution. One example from a paper by Johnson KA, Johnson DE. Department of Animal Science, Washington State University, Pullman 99164, USA. 1995 comes to the conclusion that cattle will contribute some 2% of CH4 emssions over the next 50 - 100yrs. The USDA determined some years ago that livestock emmissions in the USA represented some 0.005% of total GHG emmissions. Use the following URL reference to look at their abstract and linked papers.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?itool{{nw=}}abstractplus&db{{nw=}}pubmed&cmd{{nw=}}Retrieve&dopt{{nw=}}abstractplus&list_uids{{nw=}}8567486

Similarly recent research into CO2 natural sequestration within the oceans through remineralisation of CO2 released by life within the oceans has been overestimated by between 20 - 50% representing according to the authors approximately 3Pg/yr of CO2 finding its way into the atmosphere that has not been previously accounted for. If the ratio of CO2 to CH4 of 220:1 is maintained there is potentially another unaccounted for source of natural CH4 emissions.

Monitoring of atmospheric concentrations of CH4 were found to decline during the 1997/98? el nino event and this reduction was assigned to the fact that substantial wetland drying occured during this periond. Later ongoing research has not yet been published as the paper that contained this information was released after the 2002/03 el nino and we are now even further behind having just experienced el nino 2006/07.

--[[User:Anechidna1|Anechidna1]] 12:56, 7 May 2007 (UTC)}}

Substituted at 23:46, 29 April 2016 (UTC)

==Generation, Occurrence, and AOM sections==

The "Generation" section gives an incomplete and confusing description of the geologic production of methane in addition to a very short biological route explanation, which could be expanded. The "Occurrence" section includes information on clathrate hydrates, and is largely based on a news article discussing a newly discovered source of methane in the Arctic and the section doesn't address the other prevalent sources. Finally, there's a one sentence description of AOM, which could be expanded and moved to the biological route subsection under generation; the biological route subsection could then be split into methanogenesis and methanotrophy. I plan update these sections for my wikipedia project. --[[User:Ajohnson439|Ajohnson439]] ([[User talk:Ajohnson439|talk]]) 04:08, 16 February 2019 (UTC)

==New references for the sections: Generation, Occurrence, and AOM==

In no particular order:

Thiel, Volker (2018), Wilkes, Heinz, ed., "Methane carbon cycling in the past: insights from hydrocarbon and lipid biomarkers", ''Hydrocarbons, Oils and Lipids: Diversity, Origin, Chemistry and Fate'', Handbook of Hydrocarbon and Lipid Microbiology, Springer International Publishing, pp. 1–30, doi:10.1007/978-3-319-54529-5_6-1, ISBN 9783319545295, https://doi.org/10.1007/978-3-319-54529-5_6-1.

Reeburgh, William S. (2007). “Oceanic methane biogeochemistry”. ''Chemical Reviews''. 107 (2): 486-513. https://doi.org/10.1021/cr050362v.

Etiope, Giuseppe; Lollar, Barbara Sherwood (2013). "Abiotic methane on Earth". ''Reviews of Geophysics''. '''51''' (2): 276-99. http://dx.doi.org/10.1002/rog.20011.

Whiticar, M. J. (1999). “Carbon and hydrogen isotope systematics of bacterial formation and oxidation of methane". ''Chemical Geology''. '''161''': 291-314. https://doi.org/10.1016/S0009-2541(99)00092-3.

Serrano-Silva, N.; Sarria-Guzmán, Y.; Dendooven, L.; Luna-Guido, M. (2014). “Methanogenesis and methanotrophy in soil: a review”. ''Pedosphere''. '''24''': 291-307. http://dx.doi.org/10.1016/S1002-0160(14)60016-3.

Sirohi, S. K.; Pandey, N.; Singh, B.; Puniya, A. K. (2010). “Rumen methanogens: a review”. ''Indian J Microbiol.'' '''50''' (3): 253-262. https://doi.org/10.1007/s12088-010-0061-6.

Knittel, K.; Wegener, G.; Boetius, A. (2019), McGenity, Terry J., ed., “Anaerobic Methane Oxidizers”, ''Microbial Communities Utilizing Hydrocarbons and Lipids: Members, Metagenomics and Ecophysiology'', Handbook of Hydrocarbon and Lipid Microbiology, Springer International Publishing, pp. 1-21. https://doi.org/10.1007/978-3-319-60063-5_7-1.

Bohrmann, Gerhard; Torres, Marta E. (2006), Schulz, Horst D.; Zabel, Matthias, eds., “Gas Hydrates in Marine Sediments”, ''Marine Geochemistry'', Springer Berlin Heidelberg, pp. 481-512, https://doi.org/10.1007/3-540-32144-6_14.

Dean, J. F.et al.(2018). “Methane feedbacks to the global climate system in a warmer world”. ''Reviews of Geophysics''. '''56''': 207-250. https://doi.org/10.1002/2017RG000559.

Moore, T. A. (2012). “Coalbed methane: A review”. ''International Journal of Coal Geology''. '''101''': 36-81, http://dx.doi.org/10.1016/j.coal.2012.05.011.

--[[User:Ajohnson439|Ajohnson439]] ([[User talk:Ajohnson439|talk]]) 22:53, 22 February 2019 (UTC)

:Superb references. Thank you for your good taste. It might be worthwhile using these references in subsidiary articles, which might be in greater need of your help. Another action that I sometimes take when armed with strong secondary and tertiary references is that I ''replace'' primary references, often en masse, unless they are of historic significance. You do the readers a favor by upgrading references vs just putting more on the heap. When in doubt or if worried about removal of references, you can put the removals on the (this) talk page.--[[User:Smokefoot|Smokefoot]] ([[User talk:Smokefoot|talk]]) 23:41, 22 February 2019 (UTC)

:Thank you for the nice comments and advice, Smokefoot. I've added 10 refs only (for the required minimum for a PhD level Biogeochem course project). There may be superfluous references for a couple of sentences. I tried to choose appropriate refs, but am still unsure how the public is supposed to be able to access scientific journal articles that are not open access. Do we typically want to avoid these types of articles? Your help in minimizing refs at this point would be great. [[User:Ajohnson439|Ajohnson439]] ([[User talk:Ajohnson439|talk]]) 14:57, 11 April 2019 (UTC)

::Re I "am still unsure how the public is supposed to be able to access scientific journal articles that are not open access." That is an important question. Several answers: (1) the most authoritative references are the best, regardless of accessibility since we are aiming for trust/reliability, (2) some scholars can access them, (3) slowly but surely journals are becoming more accessible, ((4) not many readers actually want to read them anyway!). --[[User:Smokefoot|Smokefoot]] ([[User talk:Smokefoot|talk]]) 22:42, 11 April 2019 (UTC)

==Color==

If methane is colorless, then why does the [[Uranus]] article say, "Methane has prominent absorption bands in the visible and near-infrared (IR), making Uranus aquamarine or cyan in colour"? Is it colored only when it's a liquid, as in the clouds of Uranus? [[User:Eric Kvaalen|Eric Kvaalen]] ([[User talk:Eric Kvaalen|talk]]) 10:53, 4 September 2021 (UTC)

:[https://www.sciencedirect.com/science/article/pii/0019103578900921 This article] indicates an absorption for methane at 619 nm, which is in the visible range. Note that it has incredibly low oscillator strength, in both the gas phase and the liquid phase. That would be an orange-red absorption, which would correspond to a visual appearance of the complementary color of aquamarine or cyan. For our purposes on Earth, where we are either dealing with low density gases or small (relatively speaking) path lengths of liquids, the low oscillator strength makes these transitions, for all practical purposes, not visible. However, when dealing with the scale of clouds on a planetary atmosphere, the path length becomes much larger, probably in the tens or hundreds of kilometers. Per the [[Beer–Lambert law]], that huge a path length change can make a huge difference in what is, practically speaking, observable. The fact is that most compounds, barring fun quantum or symmetry effects causing transitions to become forbidden, do have absorption bands in the visible range. If those transitions are genuinely forbidden, then there will be zero oscillator strength, and no observed color. Often, though, "formally forbidden" transitions do actually show up, just with fairly weak oscillator strengths. This can happen for a lot of reasons, such as pressure effects. If you have a high pressure situation, with molecules regularly hitting each other, the slight amount of molecular deformations from those collisions will slightly change the geometry, and therefore deviate from the symmetry that caused a transition to be forbidden, thus giving a weak absorption spectrum. The article I've posted here doesn't indicate much increase in oscillator strength due to the liquid phase, so I'd say the bigger effects are higher concentration due to the condensed phase and much longer path length, both of which will give a higher absorptivity due to the Beer-Lambert law. --[[User:OuroborosCobra|OuroborosCobra]] ([[User talk:OuroborosCobra|talk]]) 17:25, 4 September 2021 (UTC)

::{{Ping|OuroborosCobra}} Thanks for the reply, which I only saw now since you didn't ping me. I can't access that article, but the title talks about the "vibrational overtone spectrum". Sounds like the absorption band at 619 nm is at around twice the frequency of one of the vibrations that cause absorption in the infrared. Or maybe thrice. I didn't know about that, but I see that Wikipedia has an article explainin' it ([[Overtone band]]). I came across an article that contains reflectivity spectra for Uranus and Neptune (Figure 1 of [https://arxiv.org/pdf/2201.04516.pdf Hazy blue worlds: A holistic aerosol model for Uranus and Neptune, including Dark Spots]), though I don't understand what the abscissa "I/F" means. You can see the absorption at 619 nm. From the text it seems that all the absorption bands one sees in Figure 1 are from methane. It talks about "k-tables" but I don't know what those are. It sounds like these absorption bands are not due to high pressure. So we can say that methane is slightly blue, but you need a long path length to see this. [[User:Eric Kvaalen|Eric Kvaalen]] ([[User talk:Eric Kvaalen|talk]]) 21:07, 12 February 2022 (UTC)

:::P.S. {{U|OuroborosCobra}}, I found what I/F means. "I" is intensity of radiation in a certain direction (like towards us), and "F" is the flux of incident radiation divided by π.[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6839776/] A surface that reflects equally in all directions and reflects all the radiation will have I/F equal to 1 in all directions. I and F may be functions of wavelength, in which case they're per unit wavelength or frequency. [[User:Eric Kvaalen|Eric Kvaalen]] ([[User talk:Eric Kvaalen|talk]]) 19:09, 14 February 2022 (UTC)

== Chemistry ==

What is it [[Special:Contributions/2405:201:AC01:3026:ED7B:46B:D2B4:C586|2405:201:AC01:3026:ED7B:46B:D2B4:C586]] ([[User talk:2405:201:AC01:3026:ED7B:46B:D2B4:C586|talk]]) 16:30, 11 December 2022 (UTC)

== New wetlands sub-section ==

I've added a short sub-section, "Wetlands" to Generation > Biological routes and added an image from the Global Methane Budget. These edits were made in collaboration with Drs Terhi Ruitta and Caroline Signori-Müller who have expertise in peatlands, as part of the [[Wikipedia:WiR/Global Systems Institute|WiR at the GSI]]. [[User:TatjanaClimate|TatjanaClimate]] ([[User talk:TatjanaClimate|talk]]) 11:14, 23 August 2023 (UTC)

== Methane ==

carbon atom bonded to four hydrogen atoms). It is a group-14 hydride [[Special:Contributions/49.145.161.229|49.145.161.229]] ([[User talk:49.145.161.229|talk]]) 03:40, 26 April 2024 (UTC)