Talk:Carbon-14

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I think this article, though short, is complete as the radiocarbon dating article covers the magority of important facts about this. Hence I remove the stub label.--LukeSurl 14:09, 26 Mar 2005 (UTC)

I agree that it doesn't need to be called a stub, but I would like it if someone would add some information about how C14 is industrially produced. I don't know the answer myself (that's what I went to Wiki for) other wise I would add it. --Road Not Taken 09:41, 21 Jan 2006

See the article radionuclide Jclerman 17:48, 21 January 2006 (UTC)

1 carbon 14 half-life
2 box
3 Age/dating calculations
4 deletions for benefit of authors and not readers - think about this...
5 It has been noted
6 Activity
7 elevated C-14 in oil deposits
8 i'd like to see a descritption of the decay reaction from C14 to N14.
9 C-14 and DNA
10 Wrong nuclear reactions
11 A note on C14 production in geologic strata

[edit] carbon 14 half-life

I have read from different sources in the internet that the half-life for C14 is 5715 years. Yet, here in wikipedia it appears as 5730 years. Does somebody know which the correct answer is?

See [1] for the best value as determined some years ago. As far as radiocarbon dating, the difference is not relevant since raw (Libby) dates are calibrated into calendar dates as described here [2] Jclerman 03:27, 26 January 2006 (UTC)

[edit] box

COMMENTED OUT UNTIL AN EXPLANATORY CAPTION (clarifying the meaning and relationship of each one of the entries) IS WRITTEN FOR THIS BOX:

Carbon-13	[[Isotopes of Carbon\|Isotopes]] of [[Carbon]]	Carbon-15
Produced from: Nitrogen-18 Boron-14	Decay chain	Decays to: Nitrogen-14

[edit] Age/dating calculations

I removed the calculations as the Radiocarbon dating article is the place for them and already contains adiquate discussion of correct and accepted calculations. --Vsmith 01:05, 26 June 2006 (UTC)

User:Pce3@ij.net has previously tried to insert his/her simplified calculations improperly in Half life as well as creating a fork article which has been deleted per AFD, see Wikipedia:Articles for deletion/Half-life computation. Vsmith 01:12, 26 June 2006 (UTC)

[edit] deletions for benefit of authors and not readers - think about this...

When the wants of authors are placed above the needs of readers then other wikis such as the Urban dictionary will begin to take the Wikipedia's place along with the potential of financial contributions. ...IMHO (Talk) 01:17, 26 June 2006 (UTC)

[edit] It has been noted

Could a reference for this statement be included?

"It has been noted that Carbon-14 levels in oil deposits appears to be positively correlated with radioactivity in rocks surrounding the oil deposit."

Dan Watts 18:10, 5 March 2007 (UTC)

[edit] Activity

The activity of modern standard radiocarbon is about 14 disintegrations per minute (dpm) per gram carbon (ca. 230 mBq/g).

I first thought that this means that if you have one gram of Carbon-14, then 14 atoms will disintegrate per minute, but I didn't like the phrase "per gram carbon". Then I played with the numbers and clearly this is not what the statement means. Rather, it appears if you take one gram of modern standard carbon (where is that defined?), then 14 of the contained Carbon-14 atoms will disintegrate per minute. With this interpretation, the phrase "activity of modern standard radiocarbon" seems misleading. It is not really the radiocarbon that is modern standard, it is the proportion of radiocarbon in carbon that is modern standard. I'm struggling to find a better formulation. AxelBoldt 16:17, 15 April 2007 (UTC)

The relevant standard(s) is(are) defined in [3]. Please refer to them with the NIST language. If it appears incorrect to you, contact the NIST and propose your nomenclature. Jclerman 17:18, 15 April 2007 (UTC)

Well, looking at the link the phrase "modern standard radiocarbon" does not appear to be NIST nomenclature.

I have a hard time making sense of that link though; maybe our article can explain it better. Among several others, they seem to speak of "principal modern radiocarbon standard", "International Radiocarbon Dating Standard", "absolute radiocarbon standard", "Oxalic acid standard", "Oxalic acid II standard", and I don't know which, if any, of these are synonyms, and which of these our article refers to when it says "mondern radiocarbon standard". In fact, I'm even unclear what these standards are - just certain well-defined substances? Also I don't see the number 14 dpm anywhere.

Here's my current best guess: NIST prepares a certain batch of oxalic acid and declares it "standard", mainly to fix the proportion of C-14 atoms. Now if you took an amount of this oxalic acid that contains precisely 1 gram of carbon, and waited for a minute, then 14 of the C-14 atoms would have disintegrated. Is that the intended meaning of the sentence in the article? AxelBoldt 19:38, 15 April 2007 (UTC)

Yes. The wiki article is not a lab manual. Readers who want to do their own measurements can read the details in the NIST site. Also, this article doesn't need to overlap with info in the radiocarbon dating article. Jclerman 22:37, 15 April 2007 (UTC)

I agree, it's not a lab manual, but it must be self-contained and the meaning of all statements must be clear without having to guess or read obscure external sources; or else the statements are better removed. (Especially if they are unsourced, as the 14 dpm number currently is.) AxelBoldt 04:41, 18 April 2007 (UTC)

The article as it is now states the activity of the modern radiocarbon standard, but does not define it; the standard is not discussed in the radiocarbon dating article either. Jclerman, is the definition of the modern radiocarbon standard outside the scope of both this article and the radiocarbon dating article? Whosasking (talk) 05:10, 22 February 2008 (UTC)

In my opinion details about the sample used as standard and the standard activity belong to the lab and not to a general encyclopedia. For the sake of completion the one would have to describe and discuss the backround sample used as blank, the C13 graph9ite and belemnite standards, etc. Jclerman (talk) 18:52, 22 February 2008 (UTC)

If you do this calculation

dN/dt = -λN

λ = ln2 / t_1/2

= ln2/(5730*365.25*24*60) = 2.3e-10

per mole: 2.3e-10 * 6.022e23 = 1.38e14

C14 is 1ppb: 1.385e14 / 1e12 = 138.5

per gram: 138.5/12 = 11.5 disintegrations per minute

why is there a discrepancy with the "standard" answer? 129.31.72.52 17:10, 13 May 2007 (UTC)

You are asuming that the natural abundance of C-14 is 1.000 parts per trillion. Is that figure correct or it should be approx 1 pp-trillion? Jclerman 19:28, 13 May 2007 (UTC)

[edit] elevated C-14 in oil deposits

It has been noted that carbon-14 levels in oil deposits appears to be positively correlated with radioactivity in rocks surrounding the oil deposit.

I've removed this sentence form the article until it can be verified. Whosasking 20:18, 3 June 2007 (UTC)

[edit] i'd like to see a descritption of the decay reaction from C14 to N14.

thanks Wikiskimmer 07:13, 30 June 2007 (UTC)

See: http://en.wikipedia.org/wiki/Radiocarbon_dating#Basic_physics. Jclerman 08:14, 30 June 2007 (UTC)

Hmm.. that's odd. should there be two separate articles? confusing! Wikiskimmer 17:40, 30 June 2007 (UTC)

One is about dating. Jclerman 19:44, 30 June 2007 (UTC)

still, there is alot of overlap, and in the carbon 14 page the decay equation:

\mathrm{~^{14}_{6}C}\rightarrow\mathrm{~^{14}_{7}N}+ e^- + \bar{\nu}_e

is not present. when i looked for it, it did not occur to me to look for it in the article on RADIOCARBON DATING! i still say it's confusing. Wikiskimmer 06:21, 1 July 2007 (UTC)

Sectionized the article and added a Radiocarbon dating blank section with a See main tag to make the link more obvious. A brief summary could be added to the empty section, but it's all just a click away. Vsmith 14:39, 4 July 2007 (UTC)

[edit] C-14 and DNA

I would like to know if C14 present in DNA molecules could affect in some way the behaviour of this complex system of reproduction, to say, mutations.--Jorgeluismireles 01:43, 13 May 2006 (UTC)

A paragraph citing Williams, C.P. Recycling greenhouse gas fossil fuel emissions into low radiocarbon food products to reduce human genetic damage. Environmental Chemistry Letters. 2007 May 23 (online). DOI: 10.1007/s10311-007-0100-7. Retrieved on 2007-06-28., was contributed by Biochem92. The paper proposes that

...human genetic damage can be significantly reduced using low radiocarbon foods produced by growing plants in CO2 recycled from ordinary industrial greenhouse gas fossil fuel emissions...

Since the paper is recent (and hasn't had time to be reviewed by the community), and since the author of this "proposal" is in the business of selling isotopically-enriched nutritional supplements, I've moved the claims here for discussion. Does a "proposal", written by an interested party, published in Environmental Chemistry Letters, qualify for inclusion in an encyclopedia? Whosasking 01:21, 5 July 2007 (UTC)

Well, technically it looks like it has been peer-reviewed by the community (= 2+ reviewers). After all, it is published in a proper scientific journal from a reputable publisher - and that's no mean feat. It's probably fairer to say that there hasn't been time for the wider community to comment on its findings (which might take the form of comment by omission - that is, no citations for the paper). But, as far as I can tell, it has been through the peer-review mill, so it shouldn't be saying anything that's too questionable. That said, I'd have thought that other sources of radiation (ultraviolet, cosmic rays) were at least as significant (if not more so) than ingested ¹⁴C - which, after all, isn't terribly radioactive (c.f. ³²P). And some of the conclusions of the paper (e.g. regarding terrorism) are fairly bizarre. Anyway, while I must admit that my eyebrows raised when I read the section on ¹⁴C in food, I don't think your criticism of it as a "proposal" entirely holds up. It is a proper scientific paper. Still, until this subject is written about more widely (the paper's reference list doesn't appear to contain any similar works), I concur about removing it from the article. The idea simply hasn't established itself as notable. Cheers, --Plumbago 09:15, 5 July 2007 (UTC)

[edit] Wrong nuclear reactions

[Thoughtless and stupid comment removed by the author.] 147.231.12.9 14:31, 16 August 2007 (UTC)

Hi 147.231.12.9. I've responded to this back over at Radiocarbon dating. I thought I'd better leave a note here to direct any discussion to the one place. Cheers, --Plumbago 14:33, 16 August 2007 (UTC)

[edit] A note on C14 production in geologic strata

I thought it would be best for me to provide here some relevant information regarding my edit to the "Carbon-14 and fossil fuels" section, where I changed edited the last part of it to read "Presence of carbon-14 in the isotopic signature of a sample of carbonaceous material therefore indicates its possible contamination by biogenic sources or the decay of radioactive material in related geologic strata." C14 is produced in the ground by the radioactive decay of uranium and thorium. I'm sure more digging around would provide many additional references, but here are just three:

Excess carbon-14 abundances in uranium ores: Possible evidence for emission from uranium-series isotopes by D. Barker, A. J. T. Jull, and D. J. Donahue (Geophysical Research Letters, Volume 12, Issue 10, p. 737-740 [1985]) http://adsabs.harvard.edu/abs/1985GeoRL..12..737B

Carbon-14 Abundances in Uranium Ores and Possible Spontaneous Exotic Emission from U-Series Nuclides by A. J. T. Jull, D. Barker, and D. J. Donahue (Meteoritics, Vol. 20, p.676 [Dec. 1985]) http://adsabs.harvard.edu/abs/1985Metic..20..676J

14C in uranium and thorium minerals: a signature of cluster radioactivity? by R. Bonetti, et al (European Physical Journal A, Vol. 5, No. 2, 235-238 [Jun. 1999])

As you can see, geophysicist and physicists working in this particular area of study have been aware of this underground production of C14 for some time. —Preceding unsigned comment added by Greeneto (talk • contribs) 07:08, 17 October 2007 (UTC)

It is good to see that work is being done on this. At the current measurable ratio of ¹⁴C/C (~10^-15) (from Carbon-14 Abundances in Uranium Ores and Possible Spontaneous Exotic Emission from U-Series Nuclides by A. J. T. Jull, D. Barker, and D. J. Donahue(Meteoritics, Vol. 20, p.676 [Dec. 1985])http://adsabs.harvard.edu/abs/1985Metic..20..676J above) this implies that there is roughly an equal amount of uranium to carbon in the deposits (2X10^-15 ¹⁴C/U). The reactor community should be ecstatic over this news. Also, bacteria in situ couldn't reasonably affect ¹⁴C/C ratios unless there were weekend trips to the earth's surface. If these are the best references on the subject, it appears to me that labelling it an open question is more accurate. Dan Watts (talk) 18:27, 9 January 2008 (UTC)

All this is interesting, inasmuch as it's worth emphasizing that the "exotic" process being discussed in these papers is the so-called cluster decay emission of C-14 nuclei from certain nuclides of Rn and Ra. This is not the same process as spontaneous fission or induced fission, and in natural ores of U produces a good deal more C-14 than would be predicted from those other fission mechamisms. Some of these uranium daughter isotopes selectively emit C-14 nuclei as though they were alpha particles! But not C-12 or C-13. C-12 is emitted by a few other isotopes, but C-13 not by anything.

BTW, I don't understand the comment about the "reactor community" above. S B H arris 18:53, 9 January 2008 (UTC)

Considering that the referenced paper measured total ¹⁴C/U concentrations, then according to this logic, there must be ~ the same number of uranium atoms as carbon in the oil (or coal) deposits for this proposed mechanism to be the cause of the measured ¹⁴C. Dan Watts (talk) 23:12, 9 January 2008 (UTC)

I see your point, but all that supposes that C-14 stays in place, and there's no more reason to think it does, than the helium from alphas from U and Th does. A naked C-14 nucleus is going to go to gas: it will react chemically with just about anything, and I suppose will probably end up stripping O off silicate in the crust (O is the most common crustal atom) gassing out as CO. From there it may wind up in carbon deposits by whatever mechanism it is that helium winds up in natural gas at concentrations of up to 7%. And yes, almost all that He is retired alphas, because it's depleted of primordial He-3 by a factor of 100 or so. Of course, since C-14 isn't immortal but has a half life of < 6000 y, the CO carrying it will not show up as anything like 7%... S B H arris 06:59, 12 January 2008 (UTC)

It appears your understanding differs from the authors of http://adsabs.harvard.edu/abs/1985GeoRL..12..737B since the decay branching ratios of ¹⁴C they are discussing are based upon their measurement of in situ ¹⁴C. Dan Watts (talk) 22:48, 12 January 2008 (UTC)

Well, not my fault if they missed the obvious inference that the same thing will happen to C-14 nuclei created in U deposits, as happens to C-14 nuclei created in the atmosphere. Q: Which seems more likely to you: that the authors missed a mechanism, or that there really is as much uranium as carbon-12 in the average carbon deposit? You've pointed out a calculation YOU did which is inconsistant with a published paper, and contradicts known data. Okay, I pointed out a mechanism I know of, which is missed in the paper, and would tend to explain known data. Which of us is more likely to be right? If you're right, there's a mechanism missing for getting C-14 out of U deposits and into C deposits, since there surely isn't that much U in C deposits. You don't like my mechanism, even though it is strictly analogous to the way He is known to get from U deposits into C deposits. Okay, then, where's yours? S B H arris 17:41, 24 January 2008 (UTC)

I don't like your method because there is no good reason for ¹⁴C to behave like He. C is not a noble gas. It has valence electrons which can (and will) form covalent bonds. And (to answer the Q:) it seems more likely to me that there hasn't been enough time for earth's primordial ¹⁴C to disappear. I still believe that the most charitable thing to say concerning ¹⁴C in fossil fuel is that there are theories and no concensus.Dan Watts (talk) 19:31, 24 January 2008 (UTC)

C-14 produced in the atmosphere rapidly oxidizes to CO2, a fairly inert gas (as seen by its presense in natural gas, which is typically 1% CO2 or so). There's no use arguing that CO2 will react with something else in the deep earth, because it's typically present in natural gas, and that's a simple fact that you can't get away from. In U ores, you'd expect that oxygen in silicate would be the first thing C¹²⁺ would react with. So, helium production in U ores should mirror 14-CO2 production in them, and 14-CO2 in petroleum deposits should stay there with the rest of the CO2.

As for primordial C-14 still being around, you're kidding, right? How old are you assuming the Solar system is?? 4.5 B years is 775,000 half lives, and 2 raised to that power is 10^234,000, a number so gigantic it's inconceivable. If all the atoms in the universe (10^80) were C-14 that long ago, there wouldn't be a single one left by now. S B H arris 20:05, 24 January 2008 (UTC)

So, how many ¹⁴C are likely to be generated per radioactive atom, and what is the ratio of radioactive atoms to fossil fuel C atoms in the same geologic deposit? (And, yes, ¹⁴C in the oil doesn't give the earth a long history.) Dan Watts (talk) 20:40, 24 January 2008 (UTC)

Dan Watts is a young earth creationist. He assumes on the basis of Genesis in the Bible that the earth has not been in existence more than several thousand years. So here's the deal, editors, right now we have a young earth creationist systematically contaminating the Carbon-14 page with misinformation, as motivated by his belief in a religious dogma. Every edit by Watts needs to be examined thoroughly, and either corrected or removed. I would do it myself but at the time right now that I'm writing this (where I've just discovered what Watts has been doing) I don't have the time to dig into this (though I'll be coming back later on to do some further investigation). As one example of the misinformation he's put in the article is where he wrote, "measured amounts of 14C/U in uranium-bearing ores imply vast quantities of uranium, roughly half as much as the carbon in the deposits, to supply the 10-15 14C/C measured" and then gives a citation. But the citation doesn't actually back up what he wrote. Todd Greene

Paul Giem is a Seventh Day Adventist who teaches *medicine* at Loma Linda University (a Seventh Day Adventist school). Giem has never published a single research article in a professional science publication on carbon-14, radiophysics, radiometric dating, geology, or geophysics in his life. Why is Giem being cited as substantiating anything in this article? Answer: A young earth creationist has been corrupting this article with misinformation. We have some editing to do. Todd Greene —Preceding comment was added at 17:51, 25 February 2008 (UTC)

I forgot about the four tildes (I have not actively edited here in quite awhile), so I'll get that right this time. Dan Watts had added the following phrase: "although measured amounts of ¹⁴C/U in uranium-bearing ores imply vast quantities of uranium, roughly half as much as the carbon in the deposits, to supply the 10^-15 ¹⁴C/C measured." He put in this citation in support of that: "Abundances in Uranium Ores and Possible Spontaneous Exotic Emission from U-Series Nuclides" by A. J. T. Jull, D. Barker, and D. J. Donahue (Meteorics, vol. 20, Dec. 1985, p. 676). Of course, in that brief note written by them - please go read it - they clearly state that "we are left with the interpretation that ¹⁴C decay of a nuclide in the U-decay series is responsible for most of the observed ¹⁴C." Additionally, they do not say anything about the measured amounts implying any "vast quantities of uranium." As seen in discussion above, that idea is merely being imposed on the article without justification by Dan Watts. When a scientist tells you one thing, and a young earth creationist tells you something quite different yet pretends that the scientist backs up what the young earth creationist has told you, then you know that the scientist is being misrepresented. That is the case here. Greeneto (talk) 21:03, 25 February 2008 (UTC)

<outdent> Okay. Yes, we have some cleaning to do. The oldest moon rocks have been dated to 4.5 B years by 4 different methods, all giving the same answer. This either requires a malicious god to screw up the isotope ratios (for no single mechanism will make 4 processes with 4 different rates, all pop out the same number), OR else the Earth is 6 thousand years old and the moon is 4.5 billion years old. Boy, that's some set-design. Anyway, direct C-14 dating of cave deposits goes back 40,000 y at least, and tree ring data far longer than 6,000 years. You can see hundreds of thousands of snow deposit yearly-rings in ice from antarctica. A young Earth dating to a few thousand years in the face of such obvious stuff, is madness.

And look what kind of arguments I'm getting in return, by people who don't like the ideas. CO2 is not an intert case but He is? Sure, but CO2 is inert ENOUGH. It's going to difuse through dry or hot rock. It's already in natural gas, showing that this is so. I think that's pretty much the end of that argument. S B H arris 21:22, 25 February 2008 (UTC)

I haven't seen any numbers being proposed for the number of ¹⁴C nuclides/radioactive atoms or the number of radioactive atoms per C. You don't like the numbers calculated from the Jull reference, are there any quantitative values with which to replace them? Dan Watts (talk) 02:32, 3 March 2008 (UTC)

[Removed comment; article was correct after all]