itrogen Isotopes

NITROGEN INFORMATION UNDER CONSTRUCTION

Nitrogen has two naturally occurring stable isotopes (¹⁴N and ¹⁵N). For studies of stable isotope biogeochemistry we measure the ratio of ¹⁵N to ¹⁴N in samples of interest, expressed relative to the ratio in a standard of known isotopic composition, such as atmospheric air (¹⁵N/¹⁴N = 0.0036765 ^{(1) (2)}).

The d¹⁵N values of terrestrial nitrogen samples typically range from -25 to +30 per mil (parts per thousand) relative to air⁽³⁾.

Isotope	Atomic mass (ma/u)	Natural abundance (atom %)
14N	14.003074002	99.632
15N	15.00010897	0.368

See the page on the Isotopes of Nitrogen
and the centered on N.

⁽¹⁾From Table 9-1, p. 154, of David P. Mattey, 1997, Gas source mass spectrometry: isotopic composition of lighter elements, pages 154-170 in Robin Gill (editor), Modern Analytical Geochemistry, Longman (UK).

⁽²⁾The uncertainty in this value is much larger than the precision with which we can measure relative ratios, which is one reason for the use the "delta" notation; page 32 in Robert E. Criss, 1999, Principles of Stable Isotope Distribution, Oxford University Press.

⁽³⁾From Figure 2-29, p. 113, of Arthur H. Brownlow, 1996, Geochemistry, Prentice-Hall.