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| Titel |
Hydrological controls on dissolved organic carbon exports from a - French
Pyrenean - mountainous peatland |
| VerfasserIn |
Thomas Rosset, Laure Gandois, Jean-Marc Antoine, Roman Teisserenc, Stephane Binet |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250145254
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| Publikation (Nr.) |
 EGU/EGU2017-9176.pdf |
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| Zusammenfassung |
| At the catchment scale, peatlands disproportionally contribute to dissolved organic carbon
(DOC) exports to surface waters. Rare attempts have been made to quantify and characterize
these exports from mountainous peatlands where topography induce intense climatic
events. The specific DOC contribution from the peatland has been tracked using
fDOM (fluorescence of dissolved organic matter) sensors deployed both upstream
and downstream of a mountainous (1340m) peatland in the Pyrenees. These high
frequency (30 min) measurements have been coupled with water level, discharge and
meteorological survey in order to identify controlling factors on DOC concentrations and
fluxes.
This study highlights strong hydrological controls on DOC concentrations and fluxes at the
outlet of the peatland, especially during short and intense events of flood. Mass flux ranges
are highly variable, averaged at 52g.h−1 for low flows periods and reaching 3.5kg.h−1 during
extreme hydrological events. From September 2014 to March 2015, 75% of the DOC
mass flux transited during 39 different flood events which represent 40% of the
timescale.
Water table levels fluctuates in the [0, - 45] cm range. During the high flow
events, the highest DOC concentrations are associated with a narrow range of water
table levels [-9, -15] cm. The relations between runoff and concentration during
flood events showed two hysteretic behaviours: counter clockwise for floods with a
maximum runoff inferior to 30 L.s−1 clockwise for events with a superior runoff,
(DOC maximum concentration seems to be diluted by overflow from the upstream
watershed). When considering the topographical watershed, a specific flux of 0.76 g C
.m−2.yr−1 can be estimated. When reported to the peatland area, it reaches 32.3 g C
.m−2.yr−1. During hot moments of short and intense floods, peatlands constitute
hot spots of DOC exports to the surface waters in this mountainous watershed. |
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