Assessment of two non-invasive techniques for measuring turbulent benthic fluxes in a shallow lake
2024
Breton, Felipe | Calabro-Souza, Guilherme | Lorke, Andreas | Dubois, Philippe | Jodeau, Magali | Moilleron, Régis | Vinçon-Leite, Brigitte | Jan, Jiří | Borovec, Jakub | Lemaire, Bruno, J. | ISBB, Biology Centre CAS | University of South Bohemia | Laboratoire Eau Environnement et Systèmes Urbains (LEESU) ; École des Ponts ParisTech (ENPC)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12) | Laboratoire d'Hydraulique Saint-Venant / Saint-Venant laboratory for Hydraulics (LHSV) ; École des Ponts ParisTech (ENPC)-EDF R&D (EDF R&D) ; EDF (EDF)-EDF (EDF) | Technical University of Kaiserslautern (TU Kaiserslautern) | Hydrosystèmes continentaux anthropisés : ressources, risques, restauration (UR HYCAR) ; Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) | AgroParisTech | École des Ponts ParisTech | AgroParisTech | OSU EFLUVE | Jihočeská Univerzita (République Tchèque) | Ministère de l'agriculture tchèque | Ministère de l'environnement tchèque
International audience
Mostrar más [+] Menos [-]Inglés. Benthic fluxes refer to the exchange rates of nutrients and other compounds between the water column and the sediment bed in aquatic ecosystems. Their quantification contributes to our understanding of aquatic ecosystem functioning. Near-bed hydrodynamics plays an important role at the sediment-water interface, especially in shallow lakes, but it is poorly considered by traditional measuring techniques of flux quantification, such as sediment incubations. Thus, alternative sampling techniques are needed to characterize key benthic fluxes under in-situ hydrodynamic conditions. This study aimed to evaluate the performance of two promising methods: relaxed eddy accumulation (REA) and mass transfer coefficient (MTC). We applied them in a hyper-eutrophic shallow lake to measure the fluxes of ammonium, phosphate, iron, and manganese ions. For the first time, REA revealed hourly nutrient flux variations, indicating a strong lake biogeochemical dynamics at short time-scales. Daily average fluxes are of similar orders of magnitude for REA and MTC for ammonium (24 and 42 mmol m2 d-1), manganese (1.0 and 0.8), and iron (0.8 and 0.7) ions. They are one order of magnitude higher than fluxes estimated from sediment incubations, due to the difficulty in reproducing in-situ oxygen and hydrodynamic conditions in the laboratory. Although the accuracy of both techniques needs to be improved, the results revealed their potential: REA follows the short-term biogeochemical dynamics of sediments, while MTC could be widely used for lake monitoring because of its simpler implementation.
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