Talk:Suess effect

carbon-12 vs. ¹²C

I was wondering what the motivation was for the alteration between these two forms. Naturally, the first time you use ¹²C, it's good to include it in parentheses (as you did), but after that the alteration still happens. (I'm referring to the general case here, e.g., ¹⁴N as well, not just ¹²C itself.) Was this deliberate? If so, why? I'm not overly concerned about this mind you, mainly curious. Ben Hocking ^{(talk|contribs)} 13:39, 19 October 2007 (UTC)

Yeah, we need to be consistent with this. It's written this way because I just started the article last night -- it's at the brain-dump stage and will need polishing, referencing and so on. Whatever you think looks best is fine: ¹²C or carbon-12. Raymond Arritt 13:45, 19 October 2007 (UTC)

Done. I went with ¹²C, although I'm considering using "Carbon-12" when it starts a sentence. What do you think about that modification? Ben Hocking ^{(talk|contribs)} 14:00, 19 October 2007 (UTC)

¹³C

The Suess effect also refers to the depletion of ¹³C which is due to the fact that plants prefer C12 to C13. See e.g. [1][2][3]. Jclerman, any reason why you have removed this in several places? --Stephan Schulz 15:15, 19 October 2007 (UTC)

I use the traditional definition by Hans and his colleagues. I've seen the C-13 effect referred, with a qualifier, as C-13 Suess effect. Jclerman 15:39, 19 October 2007 (UTC)

It seems it should still be included on this page, perhaps with that particular qualifier and its own section. Would that please everyone? (I'm too ignorant to have much of an opinion here.) Ben Hocking ^{(talk|contribs)} 15:41, 19 October 2007 (UTC)

Other acceptable definition that fits the original is not to mention c-14 but say anthropogenic admixture of. The importance of the c-14 measurements that gave origin to the concept of Suess effect was, together with Keeling's work, to alert us about the magnitude of the anthropogenic effect. Jclerman 15:59, 19 October 2007 (UTC)

Anthropogenic includes cement production and land changes also, which are depleted in c-14 but not completely. Jclerman 16:09, 19 October 2007 (UTC)

CAM values

If the discussion of photosynthetic types is relevant to the topic (Suess effect), then it should be correct. CO2 discrimination and, in consequence the carbon isotope composition values of CAM plants, vary in a wide range spanning from C4 to C3. Jclerman (talk) 05:32, 31 December 2007 (UTC)

Yes, we need more details here. I want to work in some of the data from this reference[4], e.g. Table 5.1. This article has a long way to go. Raymond Arritt (talk) 05:47, 31 December 2007 (UTC)

I don't understand why more details belong in this article rather than in ecology and geochemistry articles. The reference given appears to base the discussion on basis of isotope composition values rather than in isotope discrimination values. IMHO it is an incorrect approach that has plagued the field since studied by biologists rather than geochemists. Jclerman (talk) 10:17, 31 December 2007 (UTC)

It seem to me that isotope discrimination is one factor affecting isotope composition, and isotope composition of the plants that formed fossil fuels is one factor affecting the isotope composition of those fuels. Is that correct?--Curtis Clark (talk) 16:30, 31 December 2007 (UTC)

Yes. And the isotope compositions of the discriminated carbon depend on the isotope compositions of the respective sources of carbon (e.g., atmosphere, soil gases, etc). The observed isotope discrimination value depends on the size of the reservoir of the carbon source and on other factors that affect chemical reactions (e.g., temmperature, etc). In CAM plants the observed composition depends also on the relative proportion of C3 and C4 pathways which depends on the environment at the time of photosynthesis. Jclerman (talk) 22:28, 14 January 2008 (UTC)

¹⁴C and Isotope Fractionation

Living plants and animals do not actually have the same ratio of ¹⁴C to ¹²C as atmospheric CO₂. Just as organisms fractionate ¹³C from ¹²C, they also fractionate ¹⁴C. The magnitude of the ¹⁴C/¹²C fractionation is about twice that of the ¹³C/¹²C fractionation, because the difference in masses between ¹⁴C and ¹²C is about twice the difference in masses between ¹³C and ¹²C. An appropriate reference for this is Craig (1954) St.scholasticus (talk) 22:52, 4 May 2009 (UTC)

References

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