The molecular formula $\ce{(CH2O)106(NH3)16H3PO4}$ appears in the wikipedia entry for "anoxic bodies of water". A quick search suggests that it represents the product of photosynthesis, or the generic starting point for breakdown of organic matter in the nitrogen cycle, in particular the process of denitrification of "organic matter". On page 271 of Ref. (1) it is suggested that it represents the structure of "marine plankton". This formula seems relatively widespread in use. Exactly what "organic matter" is this supposed to represent? What is its origin (who first proposed and perpetuated its use)?


  1. Derek E. G. Briggs (Ed.), Peter R. Crowther (Ed.). Palaeobiology II (1st Ed.). Wiley-Blackwell (March 5, 2001).
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    $\begingroup$ It seems the original work denoting elemental ratio C:N:P = 106:16:1 (aka the Redfield ratio) as the most common among marine organics is Fleming, R. H., 1940. The composition of plankton and units for reporting populations and production. Proc. Pacif. Sci. Congr., 1940, Vol. 3, pp. 535-540. Unfortunately, I wasn't unable to find a full-text document yet. $\endgroup$
    – andselisk
    Jul 30 '19 at 9:18
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    $\begingroup$ Indeed from the context isn't a molecular formula but elemental ratios, so while the body of text poses a sensible question, "molecular formula" shall be removed from the title. $\endgroup$
    – Alchimista
    Jul 30 '19 at 10:10
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    $\begingroup$ @Alchimista $\ce{CH2O}$, $\ce{NH3}$, and $\ce{H3PO4}$, are molecular formulas, suggesting they are building blocks of a larger structure. There must be a good reason why this "molecular-like formula" (if you prefer) and not an elemental ratio was reported. $\endgroup$
    – Buck Thorn
    Jul 30 '19 at 14:55
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    $\begingroup$ en.m.wikipedia.org/wiki/Redfield_ratio. See also respiration and nitrogen cycle. $\endgroup$
    – Alchimista
    Jul 31 '19 at 8:17
  • $\begingroup$ @Alchimista Thanks! Yes, I saw the wikipedia page after following up on andselisk's helpful comment. I understand now that the formula was originally a ratio. If I'd known that it would have been unecessary to pose my question. And I still haven't read the explanation for why the ratio has been recast as a molecular formula, but have some leads. $\endgroup$
    – Buck Thorn
    Jul 31 '19 at 8:31

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