greenhouse gas; Lagrangian particle dispersion model; process based biogeochemical model; stable isotope; nitrous oxide (N2O)
Ibraim Erkan, Denk Tobias, Wolf Benjamin, Barthel Matti, Gasche Rainer, Wanek Wolfgang, Zhang Shasha, Kiese Ralf, Butterbach‐Bahl Klaus, Eggleston Sarah, Emmenegger Lukas, Six Johan, Mohn Joachim (2020), Denitrification Is the Main Nitrous Oxide Source Process in Grassland Soils According to Quasi‐Continuous Isotopocule Analysis and Biogeochemical Modeling, in Global Biogeochemical Cycles
, 34(6), e2019GB006.
Ibraim Erkan, Wolf Benjamin, Harris Eliza, Gasche Rainer, Wei Jing, Yu Longfei, Kiese Ralf, Eggleston Sarah, Butterbach-Bahl Klaus, Zeeman Matthias, Tuzson Béla, Emmenegger Lukas, Six Johan, Henne Stephan, Mohn Joachim (2019), Attribution of N2O sources in a grassland soil with laser spectroscopy based isotopocule analysis, in Biogeosciences
, 16(16), 3247-3266.
Ibraim Erkan, Harris Eliza, Eyer Simon, Tuzson Béla, Emmenegger Lukas, Six Johan, Mohn Joachim (2017), Development of a field-deployable method for simultaneous, real-time measurements of the four most abundant N 2 O isotopocules, in Isotopes in Environmental and Health Studies
Harris Eliza, Henne Stephan, Hüglin Christoph, Zellweger Christoph, Tuzson Béla, Ibraim Erkan, Emmenegger Lukas, Mohn Joachim (2017), Tracking nitrous oxide emission processes at a suburban site with semicontinuous, in situ measurements of isotopic composition, in Journal of Geophysical Research: Atmospheres
, 122(3), 1850-1870.
Denk Tobias R.A., Mohn Joachim, Decock Charlotte, Lewicka-Szczebak Dominika, Harris Eliza, Butterbach-Bahl Klaus, Kiese Ralf, Wolf Benjamin (2017), The nitrogen cycle: A review of isotope effects and isotope modeling approaches, in Soil Biology and Biochemistry
Stanley Sarah (2017), New Technique Could Help Scientists Track Nitrous Oxide Sources
, AGU, Earth & Space Science News, Washington.
Nitrous oxide (N2O) is a potent greenhouse gas (GHG) and an important anthropogenic contributor to stratospheric ozone-depletion. Its atmospheric abundance increased significantly in recent decades due to the perturbation of the nitrogen cycle mainly by growing usage of mineral fertilizers and enhanced microbial production in soils. Hence, detailed knowledge of the tempo-spatial variations of N2O emissions from soils is fundamental for developing targeted mitigation strategies. Process-oriented biogeochemical soil models are increasingly used to assess N2O budgets. Their validation strategies usually aim at minimizing the error for total N2O emissions at site scale. Hence, it remains unclear if the partitioning between specific microbial processes is adequately represented in these models and if their application at larger scales is reliable. Microbial source processes of N2O, specifically between nitrification and/ or denitrification, exhibit characteristic isotopic signatures that can be used to quantify individual N2O sources. Atmospheric measurements of N2O isotopic composition may provide invaluable information for verification of individual pathways in biogeochemical models. However, up to now such measurements have been scarce and limited to low-frequency flask sampling in combination with laboratory-based mass spectrometric analysis.This project will, for the first time, conduct real-time, quasi-continuous measurements of N2O concentrations and site-specific isotopic composition at a tall tower (Beromünster), located in a rural environment on the Swiss plateau. In a “top-down” approach, using these measurements, backward Lagrangian particle dispersion modeling (FLEXPART-COSMO), and an inversion system, the source strengths of total N2O and its isotopic signatures in northern Switzerland will be determined. In a complementary “bottom-up” approach, a state of the art biogeochemical model (LandscapeDNDC) will be extended with a sub-module capable of simulating isotopic signatures of N2O emitted from soils. The model extension will be based on enrichment factors for the relevant ecosystem processes and will reflect process-specific isotopic site preferences of produced and emitted N2O. The extended LandscapeDNDC model in combination with detailed geospatial information on soil, vegetation and management will finally be used to assess site, field and regional-scale patterns of soil N2O emissions. The backward Lagrangian transport simulations will provide the link between these bottom-up estimates and the tall tower measurements and will allow checking for consistency between biogeochemistry modeling and observations and identifying weaknesses in our current understanding of the underlying processes.