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On the potential of δ 18 O and δ 15 N to assess N 2 O reduction to N 2 in soil
Author(s) -
Decock C.,
Six J.
Publication year - 2013
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1111/ejss.12068
Subject(s) - chemistry , isotope , biogeochemical cycle , nitrous oxide , stable isotope ratio , analytical chemistry (journal) , environmental chemistry , physics , organic chemistry , quantum mechanics
Summary Enhancing microbial reduction of the potent greenhouse gas nitrous oxide ( N 2 O ) to N 2 could be a promising strategy to mitigate emissions from soils, but N 2 O reduction rates are currently neither well understood nor quantified. It has been suggested that the importance of N 2 O reduction to N 2 could be estimated from relationships between δ 18 O and δ 15 N when N 2 O production and reduction occur simultaneously. We assessed the robustness of such relationships by using simple simulation models and experimental data for various scenarios, including open versus closed system isotope dynamics and collection of N 2 O fluxes over time with and without refreshing the headspace between sampling. We found that relationships between δ 18 O and δ 15 N vary dramatically with experimental conditions (such as headspace gas concentration and sampling scheme) and open versus closed system isotope dynamics, irrespective of N 2 O reduction rate. Therefore, we conclude that the simple relationships between δ 18 O and δ 15 N currently used are not robust indicators of N 2 O reduction to N 2 and strongly discourage graphical interpretations of δ 18 O and δ 15 N to determine N 2 O reduction. We recommend the development of more advanced process‐based isotope models that take into account open versus closed system isotope dynamics, experimental conditions, isotope values of precursors and other biogeochemical controls on δ 15 N and δ 18 O of N 2 O to estimate N 2 O reduction rates more reliably from natural abundance isotope values of N 2 O .