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| Titel |
Organic matter dynamics and stable isotope signature as tracers of the sources of suspended sediment |
| VerfasserIn |
Y. Schindler Wildhaber, R. Liechti, C. Alewell |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 9, no. 6 ; Nr. 9, no. 6 (2012-06-04), S.1985-1996 |
| Datensatznummer |
250007113
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| Publikation (Nr.) |
 copernicus.org/bg-9-1985-2012.pdf |
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| Zusammenfassung |
| Suspended sediment (SS) and organic matter in rivers can harm brown
trout Salmo trutta by affecting the 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.
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 of pasture and arable land downstream of the river.
The mean fraction of SS originating from upper watershed riverbed sediment decreased
from up to downstream and increased during high flow at all measuring sites along
the course of the river. During base flow conditions, the major sources of SS are
pasture, forest and arable land. The latter increased during rainy and warmer winter
periods, most likely because both triggered snow melt and thus erosion. The measured increase in DOC
and nitrate concentrations during high flow support these
modeling results. Enhanced soil erosion processes on pasture and arable
land are expected with increasing heavy rain events and less snow during
winter seasons due to climate change. Consequently, SS and organic matter in the river will increase,
which will possibly affect brown trout negatively. |
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