Research ArticleATMOSPHERIC SCIENCE

Extreme enrichment in atmospheric 15N15N

See allHide authors and affiliations

Science Advances  17 Nov 2017:
Vol. 3, no. 11, eaao6741
DOI: 10.1126/sciadv.aao6741
  • Fig. 1 Isotopic composition of N2 from natural samples and laboratory experiments.

    The covariation of all three isotopic variants of N2 is shown by plotting δ30N2 versus δ29N2. Mass-dependent fractionation curves for air and high-temperature equilibrated N2 are also shown. Error bars are smaller than the data points.

  • Fig. 2 Results of laboratory electrolysis experiments demonstrating clumped-isotope reordering.

    Initial isotopologue compositions were either N2 that had been equilibrated at 800°C (circles) or pure tank N2 (triangles). Surface chemistry effects likely became dominant below ~3 mbar. Error bars are smaller than the size of the data points.

  • Fig. 3 Calculated global, annual mean outputs from the WACCM-X model (year 2001).

    (A) Temperatures, (B) species concentrations, and (C) gas-phase thermal reaction rates relevant to N–N bond rupture and formation are shown. Nonthermal effects are important in the upper atmosphere but are not included in these calculations. Photolysis reactions have been omitted from this plot.

  • Fig. 4 Applications of the Δ30 tracer.

    Using atmospheric Δ30 values to constrain the global denitrification rate (A) [the dashed line in (A) represents the current atmospheric Δ30 value] and the nitrogen sources of geologic N2 outgassing (B). Error bars are smaller than the size of the data points.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/11/eaao6741/DC1

    Supplementary Text

    fig. S1. Theoretical Δ30 values at isotopic equilibrium (Δ30,equil) as a function of temperature, from Wang et al. (7).

    fig. S2. Analytical tests of Δ30 accuracy.

    fig. S3. Changes in visible emission properties during electrolysis experiments.

    fig. S4. Modeled gross rates of bond-breaking (black symbols) and bond-making (red symbols) reactions in the electrolysis experiments.

    table S1. Isotopic data for air samples and heated gases.

    table S2. Isotopic data for biological experiments.

    table S3. Data for electrolysis experiments.

    table S4. Reactions used in the model of the electrolysis experiments.

    table S5. Data for volcanic N2 samples and end members used to derive mixing fractions fRS and fmantle.

    table S6. Results from diffusion experiment for verifying instrumental accuracy.

    References (4773)

  • Supplementary Materials

    This PDF file includes:

    • Supplementary Text
    • fig. S1. Theoretical Δ30 values at isotopic equilibrium (Δ30,equil) as a function of temperature, from Wang et al. (7).
    • fig. S2. Analytical tests of Δ30 accuracy.
    • fig. S3. Changes in visible emission properties during electrolysis experiments.
    • fig. S4. Modeled gross rates of bond-breaking (black symbols) and bond-making (red symbols) reactions in the electrolysis experiments.
    • table S1. Isotopic data for air samples and heated gases.
    • table S2. Isotopic data for biological experiments.
    • table S3. Data for electrolysis experiments.
    • table S4. Reactions used in the model of the electrolysis experiments.
    • table S5. Data for volcanic N2 samples and end members used to derive mixing fractions fRS and fmantle.
    • table S6. Results from diffusion experiment for verifying instrumental accuracy.
    • References (47–73)

    Download PDF

    Files in this Data Supplement:

Stay Connected to Science Advances

Navigate This Article