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Influence of 15 N enrichment on the net isotopic fractionation factor during the reduction of nitrate to nitrous oxide in soil
Author(s) -
Mathieu Olivier,
Lévêque Jean,
Hénault Catherine,
Ambus Per,
Milloux MarieJeanne,
Andreux Francis
Publication year - 2007
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.2979
Subject(s) - chemistry , fractionation , nitrous oxide , denitrification , substrate (aquarium) , nitrate , stable isotope ratio , isotope , enrichment factor , nitrogen , isotope fractionation , isotopes of nitrogen , isotopic signature , environmental chemistry , isotope analysis , analytical chemistry (journal) , chromatography , ecology , heavy metals , physics , organic chemistry , quantum mechanics , biology
Nitrous oxide, a greenhouse gas, is mainly emitted from soils during the denitrification process. Nitrogen stable‐isotope investigations can help to characterise the N 2 O source and N 2 O production mechanisms. The stable‐isotope approach is increasingly used with 15 N natural abundance or relatively low 15 N enrichment levels and requires a good knowledge of the isotopic fractionation effect inherent to this biological mechanism. This paper reports the measurement of the net and instantaneous isotopic fractionation factor ( α s/p i ) during the denitrification of NO 3 −to N 2 O over a range of 15 N substrate enrichments (0.37 to 1.00 atom% 15 N). At natural abundance level, the isotopic fractionation effect reported falls well within the range of data previously observed. For 15 N‐enriched substrate, the value of α s/p iwas not constant and decreased from 1.024 to 1.013, as a direct function of the isotopic enrichment of the labelled nitrate added. However, for enrichment greater than 0.6 atom% 15 N, the value of α s/p iseems to be independent of substrate isotopic enrichment. These results suggest that for isotopic experiments applied to N 2 O emissions, the use of low 15 N‐enriched tracers around 1.00 atom% 15 N is valid. At this enrichment level, the isotopic effect appears negligible in comparison with the enrichment of the substrate. Copyright © 2007 John Wiley & Sons, Ltd.