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| Titel |
Sediment source detection by stable isotope analysis, carbon and nitrogen content and CSSI in a small river of the Swiss Plateau |
| VerfasserIn |
Yael SchindlerWildhaber, Christine Alewell, Axel Birkholz |
| 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 |
250088796
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| Publikation (Nr.) |
 EGU/EGU2014-2949.pdf |
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| Zusammenfassung |
| Suspended sediment (SS) and organic matter in rivers can harm the fauna by affecting health
and fitness of free swimming fish and by causing siltation of the riverbed. The temporal and
spatial dynamics of sediment, carbon (C) and nitrogen (N) during the brown trout spawning
season in a small river of the Swiss Plateau were assessed and C isotopes as well as the C/N
atomic ratio were used to distinguish autochthonous and allochthonous sources of organic
matter in SS loads. The visual basic program IsoSource with 13Ctot and 15N as input isotopes
was used to quantify the temporal and spatial sources of SS. We determined compound
specific stable carbon isotopes (CSSI) in fatty acids of possible sediment source areas to the
stream in addition and compared them to SS from selected high flow and low flow
events.
Organic matter concentrations in the infiltrated and suspended sediment were highest
during low flow periods with small sediment loads and lowest during high flow periods with
high sediment loads. Peak values in nitrate and dissolved organic C were measured during
high flow and high rainfall, probably due to leaching from pasture and arable land. The
organic matter was of allochthonous sources as indicated by the C/N atomic ratio and
δ13Corg.
Organic matter in SS increased from up- to downstream due to an increase in sediment
delivery from pasture and arable land downstream of the river. While the major sources of SS
are pasture and arable land during base flow conditions, SS from forest soils increased during
heavy rain events and warmer winter periods most likely due to snow melt which triggered
erosion.
Preliminary results of CSSI analysis of sediment source areas and comparison to SS of
selected events indicate that differences in d13C values of individual fatty acids are too small
to differentiate unambiguously between sediment sources. |
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