Advances in soil organic nitrogen research by mass spectrometry and synchrotron techniques

Autor: Leinweber, Peter; Kruse, Jens; Kiersch, Kristian
In:

Transfers and Transformations: Our Evolving Biosphere

Autor: Joint Conference of the Canadian Society of Soil Science & Canadian Society of Agronomy
Seite: 118 - 118
Jahr: 2010

Einordung:
Institut: Professur Bodenkunde

Abstract:
The speciation of organic nitrogen (N) compounds in soil and related environmental samples is still a challenge for soil chemistry. While limitations in 15 N nuclear magnetic resonance (NMR) spectroscopy were mentioned (Smernik & Baldoch 2005) synchrotron-based X-ray absorption near-edge structure (XANES) spectroscopy at the N K-edge became a powerful new tool in soil organic N research (Leinweber et al. 2010). Applied in conjunction with pyrolysis-field ionization mass spectrometry (Py-FIMS), N-XANES provided unequivocal evidence for up to 30 to 40% of non-protein N in soil clay fractions. Since much of this N occurred in heterocyclic compounds research efforts were undertaken to uncover various possible pathways for the formation of heteroaromatic N compounds in soils. It will be highlighted that Dr. Huang and co-workers (Dept. Soil Science, University of Saskatchewan) used Py-FIMS and N-XANES to identify N-heteroaromatics which were formed by abiotically catalyzed Maillard reactions in soil environments. Native heteroaromatic N (uracil) compounds can be transformed microbially, and this will be demonstrated by recent Py-FIMS and N-XANES results. Ongoing research looks at vegetation fire impacts to soil organic N. In order to improve the methods and data evaluation we studied the thermal degradation of peptides and quantified the proportion of “artificial” N heterocycles formed during Py-FIMS. Finally, examples will be given for the different sensitivity of Py-FIMS and N-XANES in the detection of heterocycles formed during real fire events in ecosystems.
References: Leinweber, P., J. Kruse, A. Gillespie, F.L. Walley, K.-U. Eckhardt, R.I.R. Blyth, T. Regier. 2010. Nitrogen compounds in dissolved and solid environmental samples. In: B. Singh, M. Gräfe (editors) Advances in understanding soil environments by application of synchrotron-based techniques. Developments in Soil Science 34. Elsevier. (2010) pp. 255-288. Smernik, R.J. and Baldock, J.A. 2005. Does solid-state 15 N NMR spectroscopy detect all soil organic nitrogen? Biogeochemistry, 75, 507−528.

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