SOURCE DETERMINATION OF NITROUS OXIDE BASED ON NITROGEN AND OXYGEN ISOTOPE TRACING: DEALING WITH OXYGEN EXCHANGE

Journal
METHODS IN ENZYMOLOGY, VOL 46: RESEARCH ON NITRIFICATION AND RELATED PROCESSES, PT B
ISSN
0076-6879
Date Issued
2011
Author(s)
Kool, Dorien M.
van Groenigen, Jan Willem
DOI
10.1016/B978-0-12-386489-5.00006-3
Abstract
Source determination of nitrous oxide (N(2)O) from soils has so far been complicated by methodological constraints: the frequently used (15)N tracer method could not differentiate between pathways related to nitrification, that is, nitrifier nitrification (NN), nitrifier denitrification (ND), and nitrification-coupled denitrification (NCD). To overcome this problem, a dual isotope method using both (15)N and (18)O was proposed. However, O exchange between nitrogen oxides and water has been found to disturb such a method. We here explain in detail a novel dual isotope method that allows to quantify O exchange in denitrification and to differentiate N(2)O production from NN, ND, NCD, and fertilizer denitrification (FD). The method has already been applied to a range of soils with good success. Potential of and scope for further improvement of the method are discussed.