Oxygen isotopic analysis of nitrous oxide (N2O) is increasingly used to study its sources and production pathways. However, O exchange between 18O-enriched H2O and (de)nitrification intermediates may disturb the 18O isotopic signal of N2O and complicate data interpretation in such methodology (Kool et al., Rap. Comm. Mass Spec. submitted). We set up a series of experiments to identify and quantify such O exchange in soil. For this purpose, we employed a novel 15N and 18O labeling approach: we incubated soils with different combinations of 15N labeled NH4+ and NO3-, and 18O labeled H2O and 18O labeled NO3-. O exchange appeared to be present and significant in all three soils studied. The extent of O exchange was different for the three soils, but in all soils appeared to stabilize at an equilibrium. We conclude that though the extent of O exchange differs between soil types, it is significant in most soil ecosystems. It will therefore interfere with interpretation of 18O-N2O analyses for N2O source determination. O stable isotopes can provide a useful tool in studying N transformations, but analyses should yet be used with caution while the presence and extent of O exchange are still unclear
|Title of host publication||Proceedings of the 2007 International Annual Meetings ASA-CSSA-SSSA ASA, New Orleans, LA. November 3-9, 2007|
|Publication status||Published - 2007|
|Event||The 2007 International Annual Meetings ASA-CSSA-SSSA ASA - New Orleans, United States|
Duration: 3 Nov 2007 → 9 Nov 2007
|Conference||The 2007 International Annual Meetings ASA-CSSA-SSSA ASA|
|Period||3/11/07 → 9/11/07|
Kool, D. M., van Groenigen, J. W., Wrage, N., & Oenema, O. (2007). Source determination of N2O: the use and limitations of O isotopic analyses. In Proceedings of the 2007 International Annual Meetings ASA-CSSA-SSSA ASA, New Orleans, LA. November 3-9, 2007 (pp. 289-2). s.n..