Organic matter dynamics and stable isotopes for tracing sources of suspended sediment

Schindler Wildhaber, Yael and Liechti, Rahel and Alewell, Christine. (2012) Organic matter dynamics and stable isotopes for tracing sources of suspended sediment. Biogeosciences, Vol. 9, H. 1. pp. 1985-1996.

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Official URL: http://edoc.unibas.ch/dok/A6056181

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Suspended sediment (SS) and organic matter in rivers can harm brown trout Salmo trutta by impact on health and fitness of free swimming fish and siltation of the riverbed. The later results in a decrease of hydraulic conductivity and therefore smaller oxygen supply to the salmonid embryos. Additionally, oxygen demand within riverbeds will increase as the pool of organic matter increases. We assessed the temporal and spatial dynamics of sediment, carbon (C) and nitrogen (N) during the brown trout spawning season and used C isotopes as well as the C/N atomic ratio 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 sources of SS in respect of time and space. Organic matter fractions 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 precipitation 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 pasture and arable land. The fraction of SS originating from upper watershed riverbed sediment increased at all sites during high flow. Its mean fraction decreased from up- to downstream. During base flow conditions, the major sources of SS are pasture and arable land. The later increased during rainy and warmer periods probably due to snow melting and erosion processes. These modeling results support the measured increased DOC and NO3 concentrations during high flow.
Faculties and Departments:05 Faculty of Science > Departement Umweltwissenschaften > Geowissenschaften > Umweltgeowissenschaften (Alewell)
UniBasel Contributors:Schindler, Yael and Alewell, Christine
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Copernicus Publ.
Note:Publication type according to Uni Basel Research Database: Journal article
Identification Number:
Last Modified:08 Dec 2015 13:30
Deposited On:01 Feb 2013 08:41

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