 |
| Titel |
Progress in quantifying rates and product ratios of microbial denitrification using stable isotope approaches |
| VerfasserIn |
Reinhard Well, Caroline Buchen, Anette Giesemann, Dominika Lewicka-Szczebak, Lena Rohe, Heinz Flessa |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250114586
|
| Publikation (Nr.) |
 EGU/EGU2015-15376.pdf |
|
|
|
|
|
| Zusammenfassung |
| Although it is known since long that microbial denitrification plays a central role in N cycling
in soils due to loss of nutrient N, emissions of N2O and lowering of N leaching, few data at
the field scale are available due to the difficulty in measurement. In recent years, stable
isotope signatures of N2O such as δ18O, average δ15N (δ15Nbulk) and 15N site preference
(SP = difference in δ15N between the central and peripheral N positions of the asymmetric
N2O molecule) have been used to constrain the atmospheric N2O budget and to characterize
N2O turnover processes including N2O production and reduction by microbial denitrification.
However, the use of this approach to study N2O dynamics in soils requires knowledge of
isotope fractionation factors for the various partial processes involved, e.g. N2O production
by nitrification or fungal/bacterial denitrification, and N2O reduction by bacterial
denitrification.
Here we present recent progress on the principles of isotope fractionation modeling
to estimate N2O reduction and on the role of microbial groups and their specific
impact on isotope values. Moreover, we report and discuss approaches to determine
isotope values of produced N2O prior to its reduction as well as enrichment factors of
N2O reduction. Finally, a variety of results from lab and field studies will be shown
were N2O reduction estimates by isotope fractionation modeling are validated by
independent measurements using 15N tracing or He/O2 incubations. Methodical
improvements to increase sensitivity of the 15N tracing approach will be briefly
addressed.
We conclude that up to now SP of soil-emitted N2O proved to be suitable to constrain the
product ratio of denitrification if N2O fluxes are dominated by bacterial denitrification.
Although this approach is not yet precise enough for robust quantification of N2 fluxes,
improved precision can be obtained in future, if further progress in understanding the control
of fractionation factors of production and reduction and identifying N2O formation by
processes other than bacterial denitrification is achieved.
References:
Rohe, L., Anderson, T.-H., Braker, G., Flessa, H., Giesemann, A., Lewicka-Szczebak, D,
Wrage-Mönnig, N., Well, R. (2014) Dual isotope and isotopomer signatures of nitrous oxide
from fungal denitrification - a pure culture study. Rapid communications in mass
spectrometry, 28, 1893-1903.
Lewicka-Szczebak D, Well R, Köster JR, Fuß R, Senbayram M, Dittert K, Flessa H
(2014) Experimental determinations of isotopic fractionation factors associated with N2O
production and reduction during denitrification in soils. Geochim Cosmochim Acta
134:55-73
Lewicka-Szczebak D, Well R, Bol R, Gregory AS, Matthews GP, Misselbrook TH,
Whalley WR, Cardenas L M (2015) Isotope fractionation factors controlling isotopocule
signatures of soil-emitted N2O produced by denitrification processes of various rates. Rapid
Comm Mass Spectrometry 29:269-282 |
|
|
|
|
|
|