EESS talk on "Interactions of cyanobacterial blooms with energy fluxes across the air-water interface in lakes"

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Event details

Date and time 01.06.2021 12:1513:00  
Place and room
ZOOM
Online https://epfl.zoom.us/j/84677261593
Speaker Dr Andreas Lorke, Professor, Environmental Physics Group, Koblenz University-Landau, DE
Category Conferences - Seminars
Abstract:
Wind-induced water motions are an important physical characteristic of lakes and play a vital role in their ecology and biogeochemistry. Yet little is known about the controls on momentum transfer from wind to water and its interaction with biochemical characteristics of the water surface at low wind speed. Cyanobacterial blooms are harmful phenomena that negatively affect water quality, human and animal health. Colony-forming Microcystis is one of the most important and ubiquitous genera that can suddenly accumulate at water surfaces, forming surface scum. We studied the processes of scum formation and its response to wind-generated turbulence in a laboratory mesocosm. We observed a strong reduction of momentum transfer from wind to water with a growing scum layer. The presence of the scum increased the threshold wind speed for the onset of flow and reduced flow velocities that were generated by wind speeds above that threshold. This effect was likely caused by the presence of a film of surface-active material at the water surface (surface microlayer), which is related to the presence of Microcystis. We hypothesize that the surface microlayer plays an important, yet largely unexplored role both in Microcystis surface scum development and in energy fluxes across the air-water interface in aquatic ecosystems. In my talk, I will highlight recent results and discuss future research directions.

Short biography:
Professor Lorke is a physicist with a research focus on environmental fluid mechanics and physical limnology. In his lab, which was founded in 2008 at the University of Koblenz-Landau, the research focuses on how water flows in aquatic ecosystems are generated, how they interact with organisms, transport material and affect biogeochemical cycling. The lab's interdisciplinary research projects range from analyses of individual swimming organisms to the quantification of global biogeochemical cycles. With the findings, the lab contribute to the understanding of how water systems are affected by global change and how water resources management can be improved to provide sustainability and to maintain biodiversity.

Practical information

  • General public
  • Free
  • This event is internal

Organizer

  • EESS - IIE

Tags

Environmental fluid dynamics physical limnology cyanobacterial blooms turbulence water quality surface microlayer

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