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Alfred Johny Wüest

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Related publications (118)

Page 4 of 6

Effects of alpine hydropower operations on primary production in a downstream lake

Alfred Johny Wüest, Beat Mueller

During the past century, the construction of hydropower dams in the watershed of Lake Brienz has significantly altered the dynamics of turbidity, which has important implications for lake productivity. To assess these effects, we measured in situ carbon as ...

Birkhauser Verlag Ag2007

The entire lifetime of a distinct double‑diffusive staircase in crater Lake Nyos, Cameroon

Alfred Johny Wüest

Lake Nyos, a deep crater lake, located in the north-west of Cameroon, was permanently stratified below 50 m depth due to subaquatic sources supplying warm, salty and CO2- enriched water into the deepest reaches. The high CO2 content in these source waters ...

2022

Do Microscopic Organisms Feel Turbulent Flows?

Alfred Johny Wüest

Microscopic organisms in aquatic environments are continuously exposed to a variety of physical and chemical conditions. Traditionally, it is accepted that due to their small size the physiology of microscopic organisms is not affected by the moving fluid ...

Amer Chemical Soc2009

MERIS observations of phytoplankton blooms in a stratified eutrophic lake

Alfred Johny Wüest

The use of spaceborne medium resolution imaging spectrometers with neural network algorithms has proven a large potential for application with optically complex inland waters. We make use of this approach to investigate the bio-physical dynamics in a eutro ...

Elsevier Science Inc2012

Convection in Lakes

Alfred Johny Wüest, Damien Bouffard

Lakes and other confined water bodies are not exposed to tides, and their wind forcing is usually much weaker compared to ocean basins and estuaries. Hence, convective processes are often the dominant drivers for shaping mixing and stratification structure ...

2019

Methane sources and sinks in Lake Kivu

Alfred Johny Wüest, Natacha Pasche

Unique worldwide, Lake Kivu stores enormous amounts of CH4 and CO2. A recent study reported that CH4 concentrations in the lake have increased by up to 15% in the last 30 years and that accumulation at this rate could lead to catastrophic outgassing by sim ...

Amer Geophysical Union2011

Lake Baikal deepwater renewal mystery solved

Alfred Johny Wüest

Deepwater renewal by intrusions and turbulent diffusion in Lake Baikal is very effective despite the enormous depth of up to 1642 m and the permanently stable stratification below similar to 300 m depth. Temperature time series recorded at the bottom of a ...

Amer Geophysical Union2008

Boundary mixing in lakes: 2. Combined effects of shear- and convectively induced turbulence on basin-scale mixing

Alfred Johny Wüest

A detailed comparison of results from a numerical three-dimensional hydrostatic lake model with high-resolution observations of the vertical structure of the turbulent bottom boundary layer (BBL) in a medium-size lake (Lake Alpnach, Switzerland) is provide ...

Amer Geophysical Union2011

Variable sediment oxygen uptake in response to dynamic forcing

Alfred Johny Wüest

Seiche-induced turbulence and the vertical distribution of dissolved oxygen above and within the sediment were analyzed to evaluate the sediment oxygen uptake rate (J(O2)), diffusive boundary layer thickness (delta(DBL)), and sediment oxic zone depth (z(ma ...

American Society of Limnology and Oceanography2010

Interface structure and flux laws in a natural double-diffusive layering

Alfred Johny Wüest

The diffusive regime of double-diffusive convection generates staircases consisting of thin high-gradient interfaces sandwiched between convectively mixed layers. Simultaneous microstructure measurements of both temperature and conductivity from the stairc ...

Amer Geophysical Union2013

Intermittent oxygen flux from the interior into the bottom boundary of lakes as observed by eddy correlation

Alfred Johny Wüest

Turbulent oxygen transport from the overlying stratified water column into the bottom boundary layer (BBL) on the slope of a medium-sized lake was investigated using the eddy correlation (EC) technique. The seicheinduced oscillatory flow of the BBL, with a ...

American Society of Limnology and Oceanography2008

Characterisation of the subaquatic groundwater discharge that maintains the permanent stratification within Lake Kivu; East Africa

Alfred Johny Wüest

Warm and cold subaquatic groundwater discharge into Lake Kivu forms the large-scale density gradients presently observed in the lake. This structure is pertinent to maintaining the stratification that locks the high volume of gases in the deepwater. Our re ...

Public Library of Science2015

LeXPLORE: A floating laboratory on Lake Geneva offering unique lake research opportunities

Alfred Johny Wüest, Damien Bouffard, Natacha Pasche, Sébastien Lavanchy, Sébastien Manuel Lavanchy

Environmental sciences depend heavily on observational data. Successful studies of ecological processes in lakes require in-situ data that cover the relevant temporal scales from milliseconds to entire seasons. Temporal and spatial coverage requirements re ...

2021

Scaling oxygen microprofiles at the sediment interface of deep stratified waters

Alfred Johny Wüest, Damien Bouffard, Robert Vincent Schwefel

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

Effects of oligotrophication on primary production in peri-alpine lakes

Alfred Johny Wüest

During the second half of the 20th century untreated sewage released from housing and industry into natural waters led to a degradation of many freshwater lakes and reservoirs worldwide. In order to mitigate eutrophication, wastewater treatment plants, inc ...

American Geophysical Union2013

Fate of rising methane bubbles in stratified waters: How much methane reaches the atmosphere?

Alfred Johny Wüest

[ 1] There is growing concern about the transfer of methane originating from water bodies to the atmosphere. Methane from sediments can reach the atmosphere directly via bubbles or indirectly via vertical turbulent transport. This work quantifies methane g ...

Amer Geophysical Union2006

Current status and strategic way forward for long-term management of Lake Kivu (East Africa)

Alfred Johny Wüest, Natacha Pasche

Lake Kivu is one of the African Great Lakes lying in the Albertine Rift. It provides livelihoods to 5.7 million people living in the two riparian countries of the Democratic Republic of the Congo and the Republic of Rwanda. Lake Kivu is currently experienc ...

Elsevier Sci Ltd2023

Comparing effects of oligotrophication and upstream hydropower dams on plankton and productivity in perialpine lakes

Alfred Johny Wüest

In recent decades, many perialpine lakes have been affected by oligotrophication due to efficient sewage treatment and by altered water turbidity due to upstream hydropower operations. Such simultaneous environmental changes often lead to public debate on ...

Amer Geophysical Union2007

Differential Heating Drives Downslope Flows that Accelerate Mixed-LayerWarming in Ice-Covered Waters

Alfred Johny Wüest, Damien Bouffard, Hugo Nicolás Ulloa Sánchez

In ice-covered lakes, penetrative radiation warms fluid beneath a diffusive boundary layer, thereby increasing its density and providing energy for convection in a diurnally active, deepening mixed layer. Shallow regions are differentially heated to warmer ...

2019

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

Alfred Johny Wüest, Beat Mueller

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. ...

American Society of Limnology and Oceanography2010