Hanspeter Zöllig has been awarded the 2016 Otto Jaag Water Protection Prize for his dissertation entitled “Electrolysis for the Treatment of Stored Source-Separated Urine”, which examined how electrolysis can be employed to recover nitrogen from urine. The prize recognises excellent PhD theses and masters dissertations in the fields of water protection and hydrology. Read more
Direct sensing of total alkalinity profile in a stratified lake
We demonstrate the direct detection of a total alkalinity depth profile through the use of an integrated thin layer electrochemical modulation instrument which acts as an alkalinity sensor. The technique uses a chemically selective proton pump that alters the concentration of hydrogen ions in the thin layer sample. As the proton pump releases hydrogen ions the resulting pH is recorded at the pH probe placed directly opposite the thin sample gap. This results in an acid-base titration that takes place directly in the thin layer sample and therefore obviates the need for traditional sample manipulation. Collected samples from a stratified lake were assessed with this alkalinity probe to record a total alkalinity profile, indicating a substantial increase from 2.59 to 4.11 mM with depth. Results of the new method were in excellent agreement with titration alkalinity data, and offer the potential for autonomous on site measurements of this key parameter.
Effects of climate change on deepwater oxygen and winter mixing in a deep lake (Lake Geneva): Comparing observational findings and modeling
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 resulting in decreased deepwater oxygen levels. The analysis of 43 years of monitoring data from Lake Geneva shows no decreasing trend neither in the areal hypolimnetic mineralization rate nor in the extent of hypoxia. Instead, hypoxic conditions are predominantly controlled by deep mixing in winter and much less by the trophic variations over the past decades. To reproduce winter mixing, the one-dimensional hydrodynamic model SIMSTRAT was specially adapted to deep lakes and run for several climate scenarios. The simulations predicted a decrease in the maximum winter mixing depth from an average of ∼172 m for 1981–2012 to ∼136 m and ∼127 m in response to predicted atmospheric temperatures between 2045–2076 and 2070–2101 according to Intergovernmental Panel on Climate Change scenarios. Concurrently, events with complete homogenization of temperature and oxygen in winter will decrease by ∼50%. Consequently, the hypolimnetic oxygen concentrations will significantly decrease. These results demonstrate that changes in deep mixing can have stronger impact than eutrophication on the deepwater oxygen levels of oligomictic lakes.
Schwefel,R.; Gaudard,A.; Wüest,A.; Bouffard,D. (2016) Effects of climate change on deepwater oxygen and winter mixing in a deep lake (Lake Geneva): Comparing observational findings and modeling, Water Resources Research, 52(11), 8811-8826, doi:10.1002/2016WR019194, Institutional Repository
The intricacies of Lake Kivu and of the methane stored in its deep waters could easily keep an entire research institute busy. Our research aims at creating the knowledge needed to support a sustainable and safe exploitation of the methane resource.
Wastewater is a source of antibiotic resistant bacteria.
We study their dissemination in the aquatic environment, and strategies to remove them.
Drilliing sediment cores (~600.000 years) from the highly alkaline Lake Van in Anatolia to reveal the climate history.
Lakes store large amounts of heat. To what extent can this heat be used to replace the use of fossil fuels or electricity for heating and cooling purposes?