 |
| Titel |
Tree-ring cellulose exhibits several distinct intramolecular 13C signals |
| VerfasserIn |
Thomas Wieloch, Ina Ehlers, David Frank, Arthur Gessler, Michael Grabner, Jun Yu, Jurgen Schleucher |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250150281
|
| Publikation (Nr.) |
 EGU/EGU2017-14723.pdf |
|
|
|
|
|
| Zusammenfassung |
| Stable carbon isotopes are a key tool in biogeosciences. Present applications including
compound-specific isotope analysis measure 13C/12C ratios (δ13C) of bulk material or of
whole molecules. However, it is well known that primary metabolites also show
large intramolecular 13C variation – also called isotopomer variation. This variation
reflects 13C fractionation by enzyme reactions and therefore encodes metabolic
information. Furthermore, δ13C must be considered an average of the intramolecular 13C
distribution.
Here we will present (1) methodology to analyse intramolecular 13C distributions of
tree-ring cellulose by quantitative 13C NMR (Chaintreau et al., 2013, Anal Chim Acta, 788,
108-113); (2) intramolecular 13C distributions of an annually-resolved tree ring chronology
(Pinus nigra, 1961-1995); (3) isotope parameters and terminology for analysis of
intramolecular isotope time series; (4) a method for correcting for heterotrophic C
redistribution.
We will show that the intramolecular 13C distribution of tree-ring cellulose shows large
variation, with differences between isotopomers exceeding 10‰Ṫhus, individual 13C
isotopomers of cellulose constitute distinct 13C inputs into major global C pools such as
wood and soil organic matter. When glucose units with the observed intramolecular 13C
pattern are broken down along alternative catabolic pathways, it must be expected
that respired CO2 with strongly differing δ13C will be released; indicating that
intramolecular 13C variation affects isotope signals of atmosphere-biosphere C exchange
fluxes. taking this variation into account will improve modelling of the global C
cycle.
Furthermore, cluster analysis shows that tree-ring glucose exhibits several independent
intramolecular 13C signals, which constitute distinct ecophysiological information channels.
Thus, whole-molecule 13C analysis likely misses a large part of the isotope information
stored in tree rings. As we have shown for deuterium (Ehlers et al., 2015, PNAS, 112, 15585),
intramolecular isotope signals allow tracing plant acclimation over centuries, and
intramolecular 13C distributions will also improve our understanding of 13C signatures of
global C fluxes. |
|
|
|
|
|
|