## N$_2$O isotope approaches for source partitioning of N$_2$O production and estimation of N$_2$O reduction – validation with the $^{15}$N gas-flux method in laboratory and field studies

### Lewicka-Szczebak, Dominika ; Lewicki, Maciej Piotr ; Well, Reinhard

**Citable Link (URL):**http://resolver.sub.uni-goettingen.de/purl?gs-1/17686

##### Journal Article (Published version)

##### First published (peer reviewed)

Biogeosciences 2020; 17(22) p.5513-5537

##### Abstract

The approaches based on natural abundance N$_2$O stable isotopes are often applied for the estimation of mixing proportions between various N$_2$O-producing pathways as well as for estimation of the extent of N$_2$O reduction to N$_2$. But such applications are associated with numerous uncertainties; hence, their limited accuracy needs to be considered. Here we present the first systematic validation of these methods for laboratory and field studies by applying the $^{15}$N gas-flux method as the reference approach.
Besides applying dual-isotope plots for interpretation of N$_2$O isotopic data, for the first time we propose a three dimensional N2O isotopocule model based on Bayesian statistics to estimate the N$_2$O mixing proportions and reduction extent based simultaneously on three N$_2$O isotopic signatures (δ$^{15}$N, δ$^{15}$N$^{\text{SP}}$, and δ$^{18}$O). Determination of the mixing proportions of individual pathways with N2O isotopic approaches often appears imprecise, mainly due to imperfect isotopic separation of the particular pathways. Nevertheless, the estimation of N$_2$O reduction is much more robust, when applying an optimal calculation strategy, typically reaching an accuracy of N$_2$O residual fraction determination of about 0.15.

##### Sponsor:

Open-Access-Publikationsfonds 2020

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