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SUMMARY:Quantifying tidally-driven benthic oxygen exchange across permeabl
 e sediments: An aquatic eddy correlation study
DTSTART:20141104T161500
DTEND:20141104T171500
DTSTAMP:20260406T171710Z
UID:e45e8d6d8cc5e003cecc0d395a06e5ee189806b4bac5560287dc45a7
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr Daniel McGinnis\, Institute F.-A. Forel\, Faculty of Scienc
 e\, University of Geneva\, CH\nAbstract:\nPermeable sediments make up vast
  areas of coastal seas\, and represent areas of intense oxygen\, carbon an
 d nutrient turnover. However\, sediment-water column exchange is difficult
  to resolve using traditional measurement techniques.In this study\, we us
 e a combination of aquatic eddy correlation\,in situ microprofiles\, and b
 enthic chamberto investigate tidally-driven benthic oxygen dynamics in Nor
 th Sea permeable sediments. Oscillating bottom current velocities above th
 e sediment led to variations in the benthic oxygenfluxby a factor of 25. T
 he observed tidally-driven oxygen fluxes were reproduced using a simple 1-
 D model linking the bottom water turbulence to the sediment porewater adve
 ction represented as an apparent diffusivity. The 25 timesoxygen flux vari
 ability results from deeper sediment oxygen penetration and increasedoxyge
 n storage during high velocities\, which is then utilized during low flow 
 periods. The study highlights that the benthic hydrodynamics\, sediment pe
 rmeability and subsequent oscillation of porewater redox conditions are al
 l critical parameters determining the oxygen fluxin permeable sediments. W
 e discuss how these parameters may be affected by changing climate forcing
 \, and possible reasons for increasing instances of low oxygen levels in t
 he North Sea bottom waters.Short biography:\nDr McGinnis completed his PhD
 in 2003 in Civil and Environmental Engineering at Virginia Tech (USA)\, wh
 ere he studied lakes and reservoirs\, particularly management and restorat
 ion (and often mitigation). He spent considerable time at Eawag in Kastani
 enbaum during his PhD\, and continued with a postdoc studying benthic boun
 dary mixing and processes at the sediment-water interface and greenhouse g
 as transport. Slowly\, his research took him into oceanography and arctic 
 research at GEOMAR (Kiel\, Germany) and University of Southern Denmark (Od
 ense\, DK). From May 2013 – July 2014\, he received a senior scientist f
 ellowship at IGB in Berlin\, Germany where he studied benthic transport\, 
 sediment fluxes and carbon turnover in lakes. From September 2014\, he wil
 l begin as Assistant Professor in physical limnology at the University of 
 Geneva\, Institute F.-A. Forel\, Faculty of Science.
LOCATION:GR A3 31 http://plan.epfl.ch/?room=GR%20A3%2031
STATUS:CONFIRMED
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