 |
| Titel |
Soil organic carbon can be up-taken by plant roots and stored in plant biosilica: NanoSIMS and isotopic labeling evidences |
| VerfasserIn |
Anne Alexandre, Guaciara M. Santos, Jerôme Balesdent, Isabelle Basile-Doelsch, Daniel Borschneck, Patrick Cazevieille, Claire Chevassus-Rosset, Emmanuel Doelsch, Araks Harutyunyan, Laurent Lemee, Jean-Charles Mazur, Paul Reyerson, Patrick Signoret |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250108979
|
| Publikation (Nr.) |
 EGU/EGU2015-8824.pdf |
|
|
|
|
|
| Zusammenfassung |
| Plant biosilica particles called phytoliths contain occluded organic compounds (phytC). Over
the last few years, phytC content, nature, origin, paleoenvironmental meaning and impact in
the global C cycle has been the subject of increasing debate[1, 2]. Inconsistencies in phytC
quantification were fed by the scarcity of in-situ characterization of phytC in phytoliths and
by inadequate extraction methods[3]. Very recently, 14C-AMS analyses of soil organic matter
(SOM), amendments, plant tissues, atmospheric CO2 and phytolith samples, evidenced that a
small but significant pool of phytC is not photosynthetic but derived from old SOM[4,5].
From there, several investigations were started to go further into the characterization
of phytC and the mechanisms in play behind old SOM absorption by plant roots
and old SOM occlusion in plant biosilica. Here, we first reconstruct at high spatial
resolution the 3-dimentional location of phytC and its C/N signature using 3D X-ray
microscopy and Nano-scale Secondary Ion Mass Spectrometry (NanoSIMS). A
pool of phytC appears homogeneously distributed in the silica structure and its
C:N estimate is in the range of amino acid signatures[6]. Then, we use 13C and
15N-labelled amino acids monitored from an hydroponic solution to grass roots,
stems, leaves and phytoliths to evidence that amino acids are absorbed as such
by the roots and are concentrated in phytC rather than in the plant tissues. These
findings strengthen and complement the 14C evidences. Both of them dissuade
attempts to use phytC as a proxy of plant C. Further, they open new avenues of
investigation regarding the processes which drive SOM mobilization by plant uptake,
for a better understanding of soil/plant interactions involved in the terrestrial C
cycle.
[1] Santos et al. 2010. Radiocarbon 52:113
[2] Santos et al. 2012. Biogeosci. 9:1873
[3] Corbineau et al. 2013 R. Paleobot. Palyn. 197: 179
[4] Reyerson et al. 2013 AGU Fall meeting 2013 (1803125)
[5] Santos et al. 2014 AGU Fall meeting 2014 (B51A-0011)
[6] Alexandre, et al., 2014. Biogeosci. Discuss. 11, 14699Â:14727. |
|
|
|
|
|
|