Publications de Robert Vincent Schwefel

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

Alfred Johny Wüest, Robert Vincent Schwefel, Beat Mueller

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 an ...

American Society of Limnology and Oceanography2020

Oxygen consumption in seasonally stratified lakes decreases only below a marginal phosphorus threshold

Alfred Johny Wüest, Robert Vincent Schwefel

Areal oxygen (O-2) consumption in deeper layers of stratified lakes and reservoirs depends on the amount of settling organic matter. As phosphorus (P) limits primary production in most lakes, protective and remediation efforts often seek to reduce P input. ...

Springer Nature2019

Using small-scale measurements to estimate hypolimnetic oxygen depletion in a deep lake

Alfred Johny Wüest, Damien Bouffard, Robert Vincent Schwefel

Low oxygen concentrations in lakes and reservoirs are an ongoing environmental concern, particularly in light of increasing anthropogenic activity and climate change. Oxygen depletion processes in lakes are still not completely understood and a variety of ...

American Society of Limnology and Oceanography2018

Oxygen depletion in Lake Geneva

Robert Vincent Schwefel

Low oxygen concentrations remain a global concern for the ecological health of lakes. High nutrient inputs and climate-induced changes in stratification and mixing are anthropogenic threats which largely impact aquatic oxygen budgets and overall ecosystem ...

EPFL2017

Scaling oxygen microprofiles at the sediment interface of deep stratified waters

Alfred Johny Wüest, Damien Bouffard, Robert Vincent Schwefel, Miki Hondzo

Dissolved oxygen microprofiles at the sediment-water interface of Lake Geneva were measured concurrently with velocities 0.25 to 2m above the sediment. The measurements and scaling analyses indicate dissolved oxygen fluctuations and turbulent fluxes in exc ...

American Geophysical Union2017

Oxygen depletion in stratified lakes - why shallow and deep lakes react differently

Alfred Johny Wüest, Robert Vincent Schwefel

Oxygen is the most important element in natural waters for any higher aquatic life, such as fish. As with humans, almost all members of aquatic ecosystems need oxygen to breathe. Building on this, treatment of drinking water is easier for oxic than for ano ...

2016

Effects of climate change on deepwater oxygen and winter mixing in a deep lake (Lake Geneva): Comparing observational findings and modeling

Alfred Johny Wüest, Damien Bouffard, Robert Vincent Schwefel, Adrien Gaudard

Low concentrations of dissolved oxygen remain a global concern regarding the ecological health of lakes and reservoirs. In addition to high nutrient loads, climate-induced changes in lake stratification and mixing represent additional anthropogenic menace ...

American Geophysical Union2016

Effects of climate change on deep-water oxygen and winter mixing in a deep lake (Lake Geneva)

Alfred Johny Wüest, Damien Bouffard, Robert Vincent Schwefel

Oxygen is the most important dissolved gas for lake ecosystems. Because low oxygen concentrations are an ongoing problem in many parts of the oceans and numerous lakes, oxygen depletion processes have been intensively studied over the last decades and were ...

2016

Impact of deepwater mixing on hypoxia in Lake Geneva

Alfred Johny Wüest, Damien Bouffard, Robert Vincent Schwefel

Lake Geneva is recovering from its eutrophic past but no significant trend in the areal hypolimnetic oxygen depletion rate has been observed over the last 30 years. Due to the large depth of 309 m, the lake is not mixed completely every winter which can le ...

2015

Sediment oxygen uptake in Lake Geneva

Alfred Johny Wüest, Damien Bouffard, Robert Vincent Schwefel

Between 1960 and 1980, the trophic state of Lake Geneva (situated between France and Switzerland) has changed from oligotrophic to eutrophic. Since then, the areal hypolimnetic oxygen demand of 1.31 gm-2 d-1 is now the highest measured in Switzerland and l ...

2014