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SUMMARY:Stratification features in lakes: temperature stratification\, mer
 omixis\, and thermobaric stratification
DTSTART:20131015T161500
DTEND:20131015T171500
DTSTAMP:20260408T025812Z
UID:d7a57ff47a29d53b2ce602962c8435ae515f252283e4951c0bd6b346
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof.  Bertram Boehrer\, Helmholtz Centre for Environmental R
 esearch - UFZ\, Limnophysics\, Magdeburg (DE)\nAbstract:\nMany lakes show 
 a vertical stratification of their water masses at least for some extended
  time periods. Density differences in water bodies facilitate an evolution
  of chemical differences with many consequences for living organisms in la
 kes. Temperature and dissolved substances contribute to density difference
 s. Thermal stratification can be established during the warm season\, if a
  lake is sufficiently deep. On the contrary\, during the cold period\, sur
 face cooling forces vertical circulation of water masses.\nHowever\, gradi
 ents of dissolved substances may be sustained for periods much longer than
  one annual cycle. Such lakes do not experience full overturns. Photosynth
 esis in the upper water body and subsequent decomposition of organic mater
 ial in the deeper layers of a lake can sustain a gradient of dissolved sub
 stances. Three more biogeochemical cycles\, namely\, calcite precipitation
 \, iron cycle\, and manganese cycle\, are known for sustaining meromixis. 
 The presentation will close with some examples of thermobaric stratificati
 on\, i.e. the rare case where pressure effects control the thermal stratif
 ication of freshwater lakes.Dr Bertram Boehrer leads the Limnophysics Grou
 p at the Helmholtz Centre for Environmental Research – UFZ in Magdeburg 
 (Germany). He also teaches at the Faculty for Physics and Astronomy at the
  University of Heidelberg (Germany). He is physicist by training and has g
 raduated with a master’s thesis from the University of Heidelberg on the
  internal waves in Lake Constance and a PhD thesis from The Univ. of Weste
 rn Australia on convection. In the 1990s and early 2000s\, he had dedicate
 d his work to the pressing environmental concerns of lakes coming into exi
 stence in open pit mines of former East Germany. Recent scientific publica
 tions comprise quantifications of lake stratification such as thermobaric 
 effects\, meromixis\, consequences of chemical transformations and global 
 change for the stratification and deep recirculation of lakes.
LOCATION:GR A3 31 http://plan.epfl.ch/?room=GR%20A3%2031
STATUS:CONFIRMED
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