First real-time isotopic characterisation of N2O from chemodenitrification. (15th December 2019)

• Record Type: Journal Article
• Authors: Wei, Jing; Ibraim, Erkan; Brüggemann, Nicolas; Vereecken, Harry; Mohn, Joachim
• Is Part Of: Geochimica et cosmochimica acta. Volume 267(2019)
• Page Start: 17
• Page End: 32
• Publication Date: 2019-12-15
• Subjects: Chemodenitrification -- Nitrous oxide -- Site preference -- Nitrite -- Lignin derivatives; Geochemistry -- Periodicals; Meteorites -- Periodicals; Géochimie -- Périodiques; Météorites -- Périodiques; Geochemie; Astrochemie; Electronic journals; 551.905
• DOI: 10.1016/j.gca.2019.09.018
• Languages: English
• ISSNs: 0016-7037

Abstract

Graphical abstract: Abstract: Chemodenitrification can be a substantial abiotic source of nitrous oxide (N2 O) in soil. The isotopic signature of N2 O from this process could support source partitioning, but it is currently unknown in sufficient detail. In this study, we determined the isotopic composition of N2 O, produced by the reaction of nitrite (NO2 − ) with lignin, four lignin derivatives, and three types of soils, online with a quantum cascade laser absorption spectrometer (QCLAS). We present the first dataset of continuous measurements of δ 15 N bulk (δ 15 N bulk ≡ (δ 15 N α + δ 15 N β )/2), δ 18 O, and site preference (SPN2O, SPN2O ≡ δ 15 N α − δ 15 N β ) of N2 O from chemodenitrification in both chemical assays and soils. Considerable amounts of N2 O were produced by chemical reduction of NO2 −, indicating that chemodenitrification could dominate N2 O emission in NO2 − -rich environments. The values of SPN2O varied by more than 20‰ in the reactions of sodium nitrite with organic substances. Contrary to the common assumption that SPN2O values are constant for a distinct N2 O source process, our results reveal a considerable shift in SPN2O over time for most experiments. The large SPN2O variability might be explained by the multiple pathways with hyponitrous acid or nitramide as N2 O precursors. These findings provide important new information to improve our understanding about the dependency of N2 O isotopic signatures on N2 O production processes.