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| Titel |
Three-dimensional fluorescence as a tool to characterize dissolved organic matters in the rhizosphere of plants cropped in soil amended with organic wastes. |
| VerfasserIn |
Tanalou Djae, Cédric Garnier, Stéphane Mounier, Matthieu Bravin, Emmanuel Doelsch |
| 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 |
250093445
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| Publikation (Nr.) |
 EGU/EGU2014-8164.pdf |
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| Zusammenfassung |
| Three-dimensional fluorescence is well known to be a powerful technique for the chemical
characterization of dissolved organic matters (DOM). The qualification of the DOM by
fluorescence intensity could then be connected to the complexation properties toward trace
metals. To characterize DOM in the context of agricultural recycling of organic wastes,
it is necessary to measure concomitantly the fluorescence properties of DOM in
organic wastes, in the bulk-soil and in the soil affected by root activities, i.e. in the
rhizosphere. Our study aimed at evaluating the specific fluorescence fingerprint
of the different pools of DOM above-cited, as well as the consequences of their
interactions on the evolution of the three-dimensional fluorescence of the initial soil
DOM.
An in-situ experiment was conducted in Reunion Island (Indian Ocean). Two plant
species, i.e. a graminaceous species the fescue (Festuca rubra) and a dicotyledonous species
the tomato (Lycopersicon esculentum), were grown on a soil where we applied two types of
organic wastes (pig manure compost and poultry manure compost) at three rates
and a mineral fertilizer. Following this experiment, the soil either adhering to the
roots (i.e. rhizosphere) or not (i.e. bulk-soil) was sampled and the soil solution
was recovered by chemical extraction. Three-dimensional fluorescence spectra as
excitation-emission matrix (EEM) plots were recorded with a spectrofluorometer (Hitachi
F4500) and the obtained 3D spectra were processed with PARAFAC decomposition
software, leading to 3 fluorescent components (terrestrial humic-type). Emission and
excitation slits were set at 2.5 nm and a scan rate of 2400 nm.min-1 was selected for the
emission monochromator. The wavelength emission range was increased sequentially
from 200 to 600 nm and the excitation wavelength from 300 to 550 nm by 5-nm
steps.
Root activities and organic wastes induced variations of DOM quality. Three fluorescent
components of terrestrial humic-type were identified. An increase in fluorescence
intensity (normalized to DOC) was observed for the three components identified in the
bulk-soil amended with organic wastes and especially for soils that have received the
highest application rate. An increase in fluorescence intensity was also noticed in the
rhizosphere compared to the bulk-soil and even more so in soil amended with the organic
wastes.
3D fluorescence spectra support relevantly this first investigation showing the
modification of the bulk-soil and the rhizosphere DOM following the application of organic
wastes. Further characterization of DOM properties and composition will be necessary to
understand the mechanisms underlying the changes in bulk-soil DOM. These first results
support the need to consider the influence of DOM quality to better evaluate the
bioavailability of trace metals in soils. |
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