Hypolimnetic oxygen consumption by sediment-based reduced substances in former eutrophic lakes

Beat Mueller, Martin Schmid, Alfred Johny Wüest
Amer Soc Limnology Oceanography, 2010
Article

We quantified the areal hypolimnetic mineralization rate (AHM; total areal hypolimnetic oxygen depletion including the formation of reduced substances) in two formerly eutrophic lakes based on 20 yr of water-column data collected during oligotrophication. The upward diffusion of reduced substances originating from the decomposition of organic matter in the sediment was determined from pore-water profiles and related to the time of deposition. More than 80% of AHM was due to degradation of organic matter in the water column (including sediment surface) and diffusion of reduced substances from sediment layers younger than 10 yr. Sediments older than 10 yr, including the eutrophic past, accounted for similar to 15% of AHM. This "old'' contribution corresponds to a 20-43% fraction of the total sediment-based AHM. The contribution from old sediment layers to AHM is expected to be even lower in lakes with deeper hypolimnia (> 12 m). In summary, oxygen consumption in stratified hypolimnia is controlled mainly by the present lake productivity. As a result, technical lake management measures, such as oxygenation, artificial mixing, or sediment dredging, cannot efficiently decrease the flux of reduced substances from the sediment.

À propos de ce résultat

Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.

Concepts associés

Chargement

Publications associées

Chargement

Beat Mueller, Martin Schmid, Alfred Johny Wüest
Amer Soc Limnology Oceanography, 2010
Article

Résumé

Official source

https://infoscience.epfl.ch/record/186894?ln=fr

À propos de ce résultat

Concepts associés (15)

Concepts associés

Chargement

Publications associées (27)

Chargement

Afficher plus

Publications associées

Chargement

Lac

vignette|Le lac de Vaivre à Vesoul (Haute-Saône). vignette|Lac dans le parc national de Sequoia (États-Unis). vignette|Lac nahuel Huapi en Bariloche (Argentine). vignette|Le lac Hiidenvesi en Lohja (F

Eutrophisation

thumb|upright=1.6|Les fertilisants utilisés pour les cultures (phosphore et azote) dopent la croissance des plantes et des algues dans le ru jouxtant le champ cultivé. En France et en Europe, la mise

Matière organique

vignette|Le bois est essentiellement composé de matière organique (lignine et cellulose principalement), très dense en carbone. La matière organique (parfois abrégée MO) est la matière fabriquée par

Hypolimnetic Oxygen Depletion in Eutrophic Lakes

Beat Mueller, Alfred Johny Wüest

The oxygen-consuming processes in the hypolimnia of freshwater lakes leading to deep-water anoxia are still not well understood, thereby constraining suitable management concepts. This study presents data obtained from 11 eutrophic lakes and suggests a model describing the consumption of dissolved oxygen (O-2) in the hypolimnia of eutrophic lakes as a result of only two fundamental processes: O-2 is consumed (i) by settled organic material at the sediment surface and (ii) by reduced substances diffusing from the sediment. Apart from a lake's productivity, its benthic O-2 consumption depends on the O-2 concentration in the water overlying the sediment and the molecular O-2 diffusion to the sediment. On the basis of observational evidence of long-term monitoring data from 11 eutrophic lakes, we found that the areal hypolimnetic mineralization rate ranging from 0.47 to 1.31 g of O-2 m(-2) d(-1) (average 0.90 +/- 0.30) is a function of (i) a benthic flux of reduced substances (0.37 +/- 0.12 g of O-2 m(-2) d(-1)) and (ii) an O-2 consumption which linearly increases with the mean hypolimnion thickness (z(H)) up to similar to 25 m. This model predicting and interpreting the response of lakes and reservoirs to restoration measures. has important implications for predicting and interpreting the response of lakes and reservoirs to restoration measures.

Amer Chemical Soc2012

Chargement

Organic carbon mass accumulation rate regulates the flux of reduced substances from the sediments of deep lakes

Martin Schmid, Robert Vincent Schwefel, Bernhard Wehrli, Alfred Johny Wüest

The flux of reduced substances, such as methane and ammonium, from the sediment to the bottom water (Fred) is one of the major factors contributing to the consumption of oxygen in the hypolimnia of lakes and thus crucial for lake oxygen management. This study presents fluxes based on sediment porewater measurements from different water depths of five deep lakes of differing trophic states. In meso- to eutrophic lakes Fred was directly proportional to the total organic carbon mass accumulation rate (TOC-MAR) of the sediments. TOC-MAR and thus Fred in eutrophic lakes decreased systematically with increasing mean hypolimnion depth (zH), suggesting that high oxygen concentrations in the deep waters of lakes were essential for the extent of organic matter mineralization leaving a smaller fraction for anaerobic degradation and thus formation of reduced compounds. Consequently, Fred was low in the 310 m deep meso-eutrophic Lake Geneva, with high O2 concentrations in the hypolimnion. By contrast, seasonal anoxic conditions enhanced Fred in the deep basin of oligotrophic Lake Aegeri. As TOC-MAR and zH are based on more readily available data, these relationships allow estimating the areal O2 consumption rate by reduced compounds from the sediments where no direct flux measurements are available.

European Geosciences Union2017

Chargement

Hypolimnetic oxygen depletion rates in deep lakes: Effects of trophic state and organic matter accumulation

Beat Mueller, Robert Vincent Schwefel

This study investigated the consumption of oxygen (O-2) in 11 European lakes ranging from 48 m to 372 m deep. In lakes less than similar to 100 m deep, the main pathways for O-2 consumption were organic matter (OM) mineralization at the sediment surface and oxidation of reduced compounds diffusing up from the sediment. In deeper lakes, mineralization of OM transported through the water column to the sediment represented a greater proportion of O-2 consumption. This process predominated in the most productive lakes but declined with decreasing total phosphorous (TP) concentrations and hence primary production, when TP concentrations fell below a threshold value of similar to 10 mg P m(-3). Oxygen uptake by the sediment and the flux of reduced compounds from the sediment in these deep lakes were 7.9-10.6 and 0.6-3.6 mmol m(-2) d(-1), respectively. These parameters did not depend on the lake's trophic state but did depend on sedimentation rates for the primarily allochthonous or already degraded OM. These results indicate that in lakes deeper than similar to 100 m, mineralization of autochthonous OM is mostly complete by the time of sedimentary burial. This explains why hypolimnetic O-2 concentrations improve more rapidly following TP load reduction in deeper lakes relative to shallower lakes, where larger sediment-based O-2 consumption by settled OM and release of reduced substances may inhibit the restoration of hypolimnetic O-2 concentrations.

2020

Chargement

Afficher plus