![Hier klicken, um den Treffer aus der Auswahl zu entfernen](images/unchecked.gif) |
Titel |
Quantitative approach of speleothems fluorescence |
VerfasserIn |
Marine Quiers, Yves Perrette, Jérôme Poulenard, Emilie Chalmin, Morgane Revol |
Konferenz |
EGU General Assembly 2014
|
Medientyp |
Artikel
|
Sprache |
Englisch
|
Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 16 (2014) |
Datensatznummer |
250096346
|
Publikation (Nr.) |
EGU/EGU2014-11843.pdf |
|
|
|
Zusammenfassung |
In this study, we propose a framework to interpret quantitatively the fluorescence of
speleothems organic matter (OM) by the way of a bank of water-extracted organic
matter.
Due to its efficiency to described dissolved organic matter (DOM) characteritics,
fluorescence has been used to determined DOM signatures in natural systems, water
circulations, OM transfer from soils, OM evolution in soils or recently, DOM changes in
engineered treatment systems.
Fluorescence has also been used in speleothems studies, mainly as a growth indicator.
Only few studies interpret it as an environmental proxy.
Indeed, the fluorescence of OM provides information on the type of organic molecules
trapped in speleothems and their evolutions. But the most direct information given by
fluorescence is the variation of OM quantities. Actually, increase of fluorescence intensity is
generally related to an increase in OM quantity but may also be induced by calcite optical
effect or qualitative change of OM. However, analytical technics used in water environments
cannot be used for speleothem samples.
In this study we propose to give a frame to interpret quantitatively the fluorescence signal
of speleothems. 3 different samples of stalagmites from french northern Prealps were
used. To allow the quantification of the fluorescence signal, we need to measure the
fluorescence and the quantity of organic matter on the same sample. OM of speleothems
was extracted by an acid digestion method and analysed with a spectrofluorimeter.
However, it was not possible to quantify directly the OM, as the extract solvant was a
high-concentrated acid. To solve this problem, a calibration using soil extracts was
realised. Soils were chosen in order to represent the diversity of OM present in the
environment above the caves. Attention was focused on soil and vegetation types, and
landuse. Organic material was water extracted from soils and its fluorescence was also
measured. Total organic carbon was performed on the same samples. This allow
to compare the two fluorescence signals. A range of OM concentrations can be
then attributed to the speleothem signal. Fluorescence measurements were also
realised on solid samples, using the MUESLI (Muesli Uses Emission Fluorescence for
Line scanning and Imaging). Comparison with the two fluorescence signals, will
evaluate the adaptability of the concentrations range for solid measurements, generally
used.
This method offers the possibility to associate a fluorescence signal on solid speleothem,
with a non-destructive method, to an environmental range of organic carbon quantities. |
|
|
|
|
|