Can someone suggest a reference (-s) describing results of radiocarbon dating of soil organic fractions (mainly humins as the most stable fraction, e.g. Pessenda et al., 2001)?
you can look at Pessenda et al 2006 or Tonneijck et al 2008 - both published in Radiocarbon, among several pubs in this area. But the reliability of wet chemical oxidation techniques for use as indices of OM stability has been a topic of intense debate in the biogeochemistry and soil science communities over the last decade (see von Lützow et al 2008 JPNSS, Kleber 2010 Environmental Chemistry and Schmidt et al 2011 Nature for further discussions)
Thank you for your suggestions. Please let me answer you after I got familiar with these pubs. I found almost all of them.
After a short study of the references about radiocarbon dating of SOM and its fractions I was quite surprised because of the lack of consensus in this matter (see Martin and Johnson, 1995; Schaetzl and Anderson, 2005). There is no common opinion about which sequence of the OM fractions is correct: fulvic acid - humic acid - humin or fulvic acid - humin - humic acid (see e.g. Kononova, 1966; Dalsgaard, Odgaard, 2001; Pessenda et al., 2001) and therefore which fraction would give the oldest age (humic acid, humin acid or humin?) (see e.g. a review by Rice, 2001 for comparison).
I'll be thankful for further suggestions.
The very use of these fractions to separate OM of different ages/mean residence time is in itself questioned these days. If you are starting a new project, I would strongly advice you against going this route (chem separation). These extraction techniques are notoriously unreliable in terms of what they are extracting and have been discredited because the extraction procedure itself affects the nature of the organic matter that is separated. I think you should think about using other least-destructive techniques for SOM fractionation - i.e. physical or density based separation techniques coupled with some form of spectroscopy. If you haven't seen it already, see Kogel-Knabner 2000, organic geochemistry as a starting point to look at alternative techniques
Thank you for your time and hints. I have found prof. Kogel-Knabner's profile on the ResearchGate.
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