Montag, 21. Januar 2013, 16:30 - 18:00 iCal

N2 production pathways and methane oxidation in anoxic deep-waters of a Swiss eutrophic lake: Stable isotopic and molecular constraints - CANCELLED

Eberhard Clar-Saal (2B 204), Geozentrum, UZA II
Althanstrasse 14, 1090 Vienna

Seminar

The (isotope-) biogeochemical cycling of nitrogenous compounds and methane in the water column of a deep meromictic south-alpine lake

 

Nitrogen loading in lakes is partially mitigated by microbially mediated processes that take place in redox transition zones (RTZ) within the water column and in sediments. RTZ are also sites of methane (CH4) and nitrous oxide (N2O) production and consumption. As a result of anthropogenic activities, emissions of these greenhouse gases to the atmosphere have significantly increased over the past decades. Lake Lugano is a meromictic lake with a permanent chemocline at ~130 m, representing a hot-spot of quantitative redox-driven transformations involving dissolved inorganic N species, as well as CH4. In this presentation, I will address the metabolic pathways and rates involved in N and CH4 elimination in Lake Lugano, their variability in time and space, as well as the isotope effects associated with these pathways. I will particularly focus on reactions that have essentially been neglected in lacustrine studies thus far, namely the chemolithotrophic denitrification, the anarobic oxidation of ammonium (anammox) and the microaerobic/anaerobic oxidation of methane (AOM). I will provide molecular and isotopic evidence for the co-existence of anammox bacteria and sulfide-dependent denitrifiers in the water column, and I will discuss the biogeochemical mechanisms that underlie the observed spatial distributions of nitrate, ammonium and N2O isotopologues, respectively. Finally, I will discuss the potential of aerobic methane oxidation bacteria to survive and thrive under anaerobic conditions, with important implications for our understanding of methane cycling in the anoxic realms of stratified lakes worldwide.

 

Veranstalter

Prof. Dr. Moritz Lehman/Institute for Environmental Geoscience, University of Basel, Switzerland,

Kontakt

Walter Schenkeveld
University of Vienna
Department of Environmental Geosciences Center for Earth Sciences
+43 1 4277 53142
walter.schenkeveld@univie.ac.at

Erstellt am Dienstag, 05. März 2013, 17:18
Letzte Änderung am Dienstag, 05. März 2013, 17:18

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