The
global inventory of NO<sub><i>x</i></sub> (NO<sub><i>x</i></sub> = NO + NO<sub>2</sub>) emissions is poorly
constrained, with a large portion of the uncertainty attributed to
soil NO emissions that result from soil abiotic and microbial processes.
While natural abundance stable N isotopes (δ<sup>15</sup>N)
in various soil N-containing compounds have proven to be a robust
tracer of soil N cycling, soil δ<sup>15</sup>N-NO is rarely
quantified due to the measurement difficulties. Here, we present a
new method that collects soil-emitted NO through NO conversion to
NO<sub>2</sub> in excess ozone (O<sub>3</sub>) and subsequent NO<sub>2</sub> collection in a 20% triethanolamine (TEA) solution as nitrite
and nitrate for δ<sup>15</sup>N analysis using the denitrifier
method. The precision and accuracy of the method were quantified through
repeated collection of an analytical NO tank and intercalibration
with a modified EPA NO<sub><i>x</i></sub> collection method.
The results show that the efficiency of NO conversion to NO<sub>2</sub> and subsequent NO<sub>2</sub> collection in the TEA solution is
>98% under a variety of controlled conditions. The method precision
(1σ) and accuracy across the entire analytical procedure are
±1.1‰. We report the first analyses of soil δ<sup>15</sup>N-NO (−59.8‰ to −23.4‰) from
wetting-induced NO pulses at both laboratory and field scales that
have important implications for understanding soil NO dynamics
