TY  - JOUR
AU  - Lewicka-Szczebak, Dominika
AU  - Well, Reinhard
AU  - Bol, Roland
AU  - Gregory, Andrew S.
AU  - Matthews, G. Peter
AU  - Misselbrook, Tom
AU  - Whalley, W. Richard
AU  - Cardenas, Laura M.
TI  - Isotope fractionation factors controlling isotopocule signatures of soil-emitted $N_2O$ produced by denitrification processes of various rates
JO  - Rapid communications in mass spectrometry
VL  - 29
IS  - 3
SN  - 0951-4198
CY  - New York, NY
PB  - Wiley Interscience
M1  - FZJ-2015-01768
SP  - 269 - 282
PY  - 2015
AB  - RATIONALEThis study aimed (i) to determine the isotopic fractionation factors associated with N2O production and reduction during soil denitrification and (ii) to help specify the factors controlling the magnitude of the isotope effects. For the first time the isotope effects of denitrification were determined in an experiment under oxic atmosphere and using a novel approach where N2O production and reduction occurred simultaneously.METHODSSoil incubations were performed under a He/O2 atmosphere and the denitrification product ratio [N2O/(N2 + N2O)] was determined by direct measurement of N2 and N2O fluxes. N2O isotopocules were analyzed by mass spectrometry to determine δ18O, δ15N and 15 N site preference within the linear N2O molecule (SP). An isotopic model was applied for the simultaneous determination of net isotope effects (η) of both N2O production and reduction, taking into account emissions from two distinct soil pools.RESULTSA clear relationship was observed between 15 N and 18O isotope effects during N2O production and denitrification rates. For N2O reduction, diverse isotope effects were observed for the two distinct soil pools characterized by different product ratios. For moderate product ratios (from 0.1 to 1.0) the range of isotope effects given by previous studies was confirmed and refined, whereas for very low product ratios (below 0.1) the net isotope effects were much smaller.CONCLUSIONSThe fractionation factors associated with denitrification, determined under oxic incubation, are similar to the factors previously determined under anoxic conditions, hence potentially applicable for field studies. However, it was shown that the η18O/η15N ratios, previously accepted as typical for N2O reduction processes (i.e., higher than 2), are not valid for all conditions. Copyright © 2014 John Wiley & Sons, Ltd.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000346974000006
C6  - pmid:26411625
DO  - DOI:10.1002/rcm.7102
UR  - https://juser.fz-juelich.de/record/188370
ER  -