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| Titel |
Unravelling the enigmatic origin of calcitic nanofibres in soils and caves: purely physicochemical or biogenic processes? |
| VerfasserIn |
S. Bindschedler, G. Cailleau, O. Braissant, L. Millière, D. Job, E. P. Verrecchia |
| 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 ; 11, no. 10 ; Nr. 11, no. 10 (2014-05-27), S.2809-2825 |
| Datensatznummer |
250117425
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| Publikation (Nr.) |
 copernicus.org/bg-11-2809-2014.pdf |
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| Zusammenfassung |
| Calcitic nanofibres are ubiquitous habits of secondary calcium carbonate
(CaCO3) accumulations observed in calcareous vadose environments.
Despite their widespread occurrence, the origin of these nanofeatures remains
enigmatic. Three possible mechanisms fuel the debate: (i) purely
physicochemical processes, (ii) mineralization of rod-shaped bacteria, and
(iii) crystal precipitation on organic templates. Nanofibres can be either
mineral (calcitic) or organic in nature. They are very often observed in
association with needle fibre calcite (NFC), another typical secondary
CaCO3 habit in terrestrial environments. This association has
contributed to some confusion between both habits, however they are truly two
distinct calcitic features and their recurrent association is likely to be an
important fact to help understanding the origin of nanofibres. In this
paper the different hypotheses that currently exist to explain the
origin of calcitic nanofibres are critically reviewed. In addition to this, a
new hypothesis for the origin of nanofibres is proposed based on the fact
that current knowledge attributes a fungal origin to NFC. As this feature and
nanofibres are recurrently observed together, a possible fungal origin for
nanofibres which are associated with NFC is investigated. Sequential
enzymatic digestion of the fungal cell wall of selected fungal species
demonstrates that the fungal cell wall can be a source of organic nanofibres.
The obtained organic nanofibres show a striking morphological resemblance
when compared to their natural counterparts, emphasizing a fungal origin for
part of the organic nanofibres observed in association with NFC. It is
further hypothesized that these organic nanofibres may act as templates for
calcite nucleation in a biologically influenced mineralization process,
generating calcitic nanofibres. This highlights the possible involvement of
fungi in CaCO3 biomineralization processes, a role still poorly
documented. Moreover, on a global scale, the
organomineralization of organic nanofibres into calcitic nanofibres might be
an overlooked process deserving more attention to specify its impact on the
biogeochemical cycles of both Ca and C. |
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