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Quantification of Hyporheic Nitrate Removal at the Reach Scale : Exposure Times vs. Residence Times

Titelangaben

Frei, Sven ; Durejka, Stefan ; Le Lay, Hugo ; Thomas, Zahra ; Gilfedder, Benjamin Silas:
Quantification of Hyporheic Nitrate Removal at the Reach Scale : Exposure Times vs. Residence Times.
In: Water Resources Research. Bd. 55 (2019) Heft 11 . - S. 9808-9825.
ISSN 1944-7973
DOI: https://doi.org/10.1029/2019WR025540

Volltext

Link zum Volltext (externe URL): Volltext

Abstract

The rate of biogeochemical processing associated with natural degradation and transformation processes in the hyporheic zone (HZ) is one of the largest uncertainties in predicting nutrient fluxes. We present a lumped parameter model that can be used to quantify the mass loss for nitrate in the HZ operating at the scale of river reaches to the entire catchments. The model is based on using exposure times (ET) to account for the effective timescales of reactive transport in the HZ. Reach scale ET distributions are derived by removing the portion of hyporheic residence times (RT) associated with flow through the oxic zone. The model was used to quantify nitrate removal for two scenarios: (1) a 100 m generic river reach and (2) a small agricultural catchment in Brittany (France). For the field site, hyporheic RT were derived from measured in‐stream 222Rn activities and mass balance modeling. Simulations were carried out using different types of RT distributions (exponential, power law, and gamma‐type) for which ET were derived. Mass loss of nitrate in the HZ for the field site ranged from 0 to 0.45 kg day−1 depending on the RT distribution and the availability of oxygen in the streambed sediments. Simulations with power law ET distribution models only show very little removal of nitrate due to the heavy weighting toward shorter flow paths that are confined to the oxic sediments. Based on the simulation results, we suggest that using ET will likely lead to more realistic estimates for nutrient removal in river and stream networks.

Weitere Angaben

Publikationsform: Artikel in einer Zeitschrift
Begutachteter Beitrag: Ja
Zusätzliche Informationen: BAYCEER154180
Institutionen der Universität: Forschungseinrichtungen
Forschungseinrichtungen > Forschungszentren
Forschungseinrichtungen > Forschungszentren > Bayreuther Zentrum für Ökologie und Umweltforschung - BayCEER
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Geowissenschaften > Lehrstuhl Hydrologie
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Geowissenschaften > Lehrstuhl Hydrologie > Lehrstuhl Hydrologie - Univ.-Prof. Dr. Stefan Peiffer
Fakultäten
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften
Fakultäten > Fakultät für Biologie, Chemie und Geowissenschaften > Fachgruppe Geowissenschaften
Titel an der UBT entstanden: Ja
Themengebiete aus DDC: 500 Naturwissenschaften und Mathematik
500 Naturwissenschaften und Mathematik > 550 Geowissenschaften, Geologie
Eingestellt am: 24 Jan 2020 09:12
Letzte Änderung: 19 Sep 2022 12:48
URI: https://eref.uni-bayreuth.de/id/eprint/53819