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Titel |
Soils as environmental fluorescence database to explain the speleothem fluorescence signal. |
VerfasserIn |
Marine Quiers, Yves Perrette, Jérôme Poulenard, Emilie Chalmin, Morgane Revol |
Konferenz |
EGU General Assembly 2014
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 16 (2014) |
Datensatznummer |
250097023
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Publikation (Nr.) |
EGU/EGU2014-12560.pdf |
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Zusammenfassung |
In this study, we propose to use soils water-extracted organic matter (OM) as a database of
fluorescence signal, to interpret quantitatively the the fluorescence of speleothems
OM.
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.
Speleothem fluorescence can be used as an environmental proxy, to record the
past soil evolutions. Qualitative changes of OM are easily measured. However, it’s
today complicated to quantify the fluorescence signal of speleothems due to the
analytical method generally used. That’s why we propose to interpret quantitatively the
fluorescence signal of speleothems, using soil fluorescence as a database of fluorescence
signal.
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.
This soil fluorescence database will allow to interpret the past soil evolutions using
fluorescence signal as an environmental proxy. |
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