EGU2020-15588
https://doi.org/10.5194/egusphere-egu2020-15588
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

The imprint of anammox on the stable isotope compositions of nitrogen-bearing molecules

Paul Magyar1, Damian Hausherr2, Robert Niederdorfer3, Jing Wei4, Joachim Mohn4, Helmut Bürgmann3, Adriano Joss2, and Moritz Lehmann1
Paul Magyar et al.
  • 1Department of Environmental Sciences, University of Basel, Basel, Switzerland (paul.magyar@unibas.ch)
  • 2Department of Process Engineering, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
  • 3Department of Surface Waters Research and Management, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
  • 4Laboratory for Air Pollution and Environmental Technology, Empa, Swiss Federal Laboratories for Materials Testing and Research, Dübendorf, Switzerland

Stable isotope measurements of nitrogen and oxygen in nitrogen-containing molecules provide important constraints on the sources, sinks and pools of these molecules in the environment. Anammox is one of two known biological processes for converting fixed nitrogen to N2, and through its consumption of ammonium and nitrite and production of nitrate, it impacts the supply of a wide variety of fixed N molecules. Nevertheless, the isotope fractionations associated with the various anammox-associated redox reactions remain poorly constrained. We have measured the isotope effects of anammox in microbial communities enriched for the purpose of nitrogen removal from wastewater by anammox. In this system, we can replicate the ecological complexity exhibited in environmental settings, while also performing controlled experiments. We find that under a variety of conditions, the nitrogen isotope effect for the anaerobic oxidation of ammonium in this system (NH4+ to N2) is between 19‰ and 32‰, that for the reduction of nitrite (NO2 to N2) is between 7‰ and 18‰, and that for the production of nitrate (NO2 to NO3) is between -16‰ and -43‰. We propose that these ranges reflect both (1) a mixture of signals from different anammox-performing species and (2) variation of the isotope effect associated with the anammox process within a given microbial community under different conditions. We seek to understand further what factors control this variability to better interpret stable isotope measurements of N-bearing molecules in environmental settings.

How to cite: Magyar, P., Hausherr, D., Niederdorfer, R., Wei, J., Mohn, J., Bürgmann, H., Joss, A., and Lehmann, M.: The imprint of anammox on the stable isotope compositions of nitrogen-bearing molecules, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15588, https://doi.org/10.5194/egusphere-egu2020-15588, 2020