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| Titel |
New highlights of phytolith structure and occluded carbon location: 3-D X-ray microscopy and NanoSIMS results |
| VerfasserIn |
A. Alexandre, I. Basile-Doelsch, T. Delhaye, D. Borshneck, J. C. Mazur, P. Reyerson, G. M. Santos |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 3 ; Nr. 12, no. 3 (2015-02-12), S.863-873 |
| Datensatznummer |
250117811
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| Publikation (Nr.) |
 copernicus.org/bg-12-863-2015.pdf |
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| Zusammenfassung |
| Phytoliths contain occluded organic compounds called phytC. Recently, phytC
content, nature, origin, paleoenvironmental meaning and impact in the global
C cycle have been the subject of increasing debate. Inconsistencies were fed
by the scarcity of in situ characterizations of phytC in phytoliths. Here we
reconstructed at high spatial resolution the 3-D structure of
harvested grass short cell (GSC) phytoliths using 3-D X-ray microscopy. While
this technique has been widely used for 3-D reconstruction of biological
systems it has never been applied in high-resolution mode to silica
particles. Simultaneously, we investigated the location of phytC using
nanoscale secondary ion mass spectrometry (NanoSIMS). Our data evidenced
that the silica structure contains micrometric internal cavities. These
internal cavities were sometimes observed isolated from the outside. Their
opening may be an original feature or may result from a beginning of
dissolution of silica during the chemical extraction procedure, mimicking the
progressive dissolution process that can happen in natural environments. The
phytC that may originally occupy the cavities is thus susceptible to rapid
oxidation. It was not detected by the NanoSIMS technique. However,
another pool of phytC, continuously distributed in and protected by the
silica structure, was observed. Its N/C ratio (0.27) is in agreement
with the presence of amino acids. These findings constitute a basis to
further characterize the origin, occlusion process, nature and accessibility
of phytC, as a prerequisite for assessing its significance in the global C
cycle. |
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