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Cited by 51Paleontology and Stratigraphy of FossilsEarth Systems and Cosmic EvolutionGeological and Geochemical Analysis

EarthN: A New Earth System Nitrogen Model

Open access
Johnson, Benjamin W., Goldblatt, Colin·2018·Geochemistry, Geophysics, Geosystems
DOI 10.1029/2017gc007392
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Abstract

The amount of nitrogen in the atmosphere, oceans, crust, and mantle have important ramifications for Earth's biologic and geologic history. Despite this importance, the history and cycling of nitrogen in the Earth system is poorly constrained over time. For example, various models and proxies contrastingly support atmospheric mass stasis, net outgassing, or net ingassing over time. In addition, the amount available to and processing of nitrogen by organisms is intricately linked with and provides feedbacks on oxygen and nutrient cycles. To investigate the Earth system nitrogen cycle over geologic history, we have constructed a new nitrogen cycle model: EarthN. This model is driven by mantle cooling, links biologic nitrogen cycling to phosphate and oxygen, and incorporates geologic and biologic fluxes. Model output is consistent with large (2‐4x) changes in atmospheric mass over time, typically indicating atmospheric drawdown and nitrogen sequestration into the mantle and continental crust. Critical controls on nitrogen distribution include mantle cooling history, weathering, and the total Bulk Silicate Earth + atmosphere nitrogen budget. Linking the nitrogen cycle to phosphorous and oxygen levels, instead of carbon as has been previously done, provides new and more dynamic insight into the history of nitrogen on the planet.

AI snapshot

Written from the paper’s full text.

TL;DR

EarthN is a box model of Earth’s nitrogen cycle coupling biologic and geologic fluxes over 4.5 Ga, including atmosphere, ocean, sediments, crust, and mantle. It predicts dynamic N redistribution: early net mantle outgassing and atmospheric growth, followed by atmospheric drawdown after oxygenic photosynthesis and the GOE, with modern atmospheric mass strongly controlled by total bulk-silicate-Earth N.

Key findings

  • The nominal run reproduces modern atmospheric and estimated mantle N masses well: model atmosphere 3.92 vs literature 4 ×10¹⁸ kg N; mantle 12 vs 24 ± 16 ×10¹⁸ kg N; continental crust 1.8 vs 1.7–2.7 ×10¹⁸ kg N; total ocean sediments 1.2 vs 0.41 ± 0.2 ×10¹⁸ kg N (Table 4).
  • In all runs, 4.5–2.8 Ga is characterized by net mantle outgassing and atmospheric growth due to high mantle temperatures and inefficient export production; after oxygenic photosynthesis, atmospheric N is drawn down into sediments, and at the GOE increased weathering and nutrient delivery enhance drawdown via N-fixation.
  • Monte Carlo simulations (n = 1000) that result in a 1 PAN modern atmosphere are most consistent with a total bulk-silicate-Earth N budget of ∼4–6 PAN; the mantle tends to saturate at 4–4.75 PAN, and is the dominant N carrier for total N budgets below 6–7 PAN, while the atmosphere dominates at higher values.
  • Model output is higher than literature estimates for outgassing and subduction, and somewhat underestimates N-fixing, nitrification, and denitrification; the authors suggest the latter may partly reflect the lack of continental biologic N-cycling in the model.

Methods

  • Box model reservoirs: atmosphere; three shallow ocean boxes (low-latitude, high-latitude, shelf); deep ocean; reactive shelf and deep sediments; non-reactive shelf and deep sediments; and geologic reservoirs (mantle, oceanic crust, continental crust). It tracks N as N₂, NO₃⁻, and NH₄⁺, plus PO₄, O₂, K, ⁴⁰K, ⁴⁰Ar, and ³⁶Ar. Biogeochemical fluxes follow Fennel et al. [2005] with updates; geologic fluxes are driven by mantle cooling after Korenaga [2010] and Padhi et al. [2012]; O₂ history is prescribed, and oxygenic photosynthesis evolves at the nominal run.
  • Runs are for 4.5 Ga after a 10 Myr spin-up, using Matlab’s ode15s solver with relative error tolerance 1 × 10⁻⁷ and maximum step size 10⁶ years. Nominal starting conditions are total N of 4.8 PAN, with 80% in the atmosphere and 20% in the mantle (main text; Appendix B describes 4.5 PAN and 82% atmospheric). Monte Carlo simulations (n = 1000) vary upwelling, oxygenic photosynthesis start time, plate tectonics start time, weathering timescale, and hydrothermal flow rate.

Limitations

  • Stated: the model lacks continental ecosystems/continental biologic N-cycling, has simple hydrothermal treatment of oceanic crust, omits intra-plate/hotspot volcanism, does not distinguish upper/transition/lower mantle, omits mantle redox evolution and isotopes, assumes f_Ncgarc = 0.5, excludes abiotic N-fixing, does not model a specific eukaryote productivity increase, and does not capture continental growth/orogenic variations or continental lithospheric roots/cratonic K storage. It also overestimates modern atmospheric ⁴⁰Ar/³⁶Ar by about 1.5-fold and underestimates continental crust K.
  • Stated: results “should not be taken as gospel, dogma, or actuality”; many Hadean and Archean parameters are poorly constrained, and matching constraints required tuning to specific parameters (e.g., low starting atmospheric mass, 5% starting N in the atmosphere, constant net subduction of 10%, and high 50 Sv hydrothermal circulation) to reproduce 1 PAN at 3.46 Ga and 0.5 PAN at 2.7 Ga while ending at 1 PAN modern.
  • Evident from the text: modeled biologic and geologic fluxes show discrepancies from literature estimates, and the model’s simplified treatment of continental N cycling, mantle structure/redox, and isotopes limits direct comparison with the rock record.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1029/2017gc007392

Cites

83 of 83 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 77 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    The nominal run has 3.25 PAN in the mantle at modern.

    “The nominal run has 3.25 PAN in the mantle at modern.”
    Quote in the paperNot a substantial claim
  • Findingreasoning

    At the GOE, an increase in weathering drives a spike in productivity and further atmospheric draw-down due to enhanced N-fixing.

    “At the GOE, an increase in weathering drives a spike in productivity and further atmospheric draw-down due to enhanced N-fixing.”
    • Also stated in: § 4 Conclusions · plain
      “At the Great Oxidation Event, increased weathering and nutrient delivery enhances export production, which in turn enhances atmospheric drawdown via N-fixation.”
    Quote in the paperSubstantial claim
  • Findingown data

    NH4+ is the dominant bioavailable N species in the ocean before oxygenic photosynthesis.

    “First, and unsurprisingly, NH + 4 is the dominant bioavailable N species in the ocean, and PO 3- 4 remains high (∼ 1 -3 µM) before oxygenic photosynthesis.”
    Quote in the paperNot a substantial claim
  • Findingreasoning

    NH4+ and NO3- are at about the same concentration in the Proterozoic.

    “Third, NH + 4 and NO - 3 are at about the same concentration in the Proterozoic.”
    Quote in the paperSubstantial claim
  • Findingreasoning

    Biologic N fluxes are low prior to oxygenic photosynthesis due to lower overall productivity and burial.

    “Biologic N fluxes (Fig. 7) are low prior to oxygenic photosynthesis, due to lower overall productivity and burial.”
    Quote in the paperSubstantial claim
  • May combine two claims. 47
  • Classified as probably not a substantial claim. 22
  • Borderline: one of the tests for a substantial claim is unclear. 1
  • The quote only partly states this claim. 2

  • May combine two claims.

    Findingown data

    While the nominal run reproduces modern N distribution well, there are discrepancies between modeled biologic and geologic fluxes and estimates of these fluxes from the literature.

    “While the nominal run reproduces modern N distribution well, there are discrepancies between modeled biologic and geologic fluxes and estimates of these fluxes from the literature (Fig. 4).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning

    At about 1.6 Ga, the mantle and atmosphere have equal N budgets, and the mantle continues to increase at the expense of all other reservoirs until the present day.

    “At about 1.6 Ga, the mantle and atmosphere have equal N budgets, and the mantle continues to increase at the expense of all other reservoirs until the present day.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingcitation

    There is a small oxygen oasis in the shelf ocean box, which is consistent with evidence for localized oxic conditions prior to widespread oxygenation at the GOE.

    “We also note that there is a small oxygen oasis in the shelf ocean box, which is consistent with evidence for localized oxic conditions prior to widespread oxygenation at the GOE [Anbar et al., 2007]”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Anbar et al., 2007

      Not checked in the free run.

  • May combine two claims.

    Findingreasoning

    Coincident with and caused by the appearance of oxygenic photosynthesis, the atmosphere is drawn down, with an increase in all the geologic N reservoirs.

    “Then, coincident with, and caused by, the appearance of oxygenic photosynthesis, the atmosphere is drawn down, with an increase in all the geologic N reservoirs.”
    • Also stated in: § 4 Conclusions · plain
      “After the evolution of oxygenic photosynthesis, atmospheric N is immediately drawn down and sequestered in sediments due to increased export production.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning

    The balance between NH4+ and NO3- in the Proterozoic is the result of O2 levels and depends on the O2 forcing scheme, which sets Proterozoic O2 levels at 1% of modern.

    “This balance is the result of O 2 levels, and so is dependent on our O 2 forcing scheme, which sets Proterozoic O 2 levels at 1% of modern.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning

    The model somewhat underestimates N-fixing, nitrification, and denitrification.

    “The model somewhat underestimates N-fixing, nitrification, and denitrification.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingnone given

    Deep ocean sediments increase most quickly, with continental crust and the mantle increasing more slowly.

    “Deep ocean sediments increase most quickly, with continental crust and the mantle increasing more slowly.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The increase in burial is reflected in the increase in N in ocean sediments and in all biologic N fluxes.

    “The increase in burial is reflected in the increase in N in ocean sediments and in all biologic N fluxes (Fig. 4).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingcitation

    The nominal run's mantle N value is somewhat lower than but within the estimated mantle N budget from Johnson and Goldblatt [2015] of 7 ± 4 PAN.

    “The mantle value, specifically, 436 is somewhat lower, but within the estimated mantle N budget from Johnson and Goldblatt 437 [2015], which is 7 ± 4 PAN.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Johnson and Goldblatt [2015]

      Not checked in the free run.

  • May combine two claims.

    Findingnone given

    The model output reproduces the K content of the mantle well, but underestimates the continental crust concentration.

    “While the model output reproduces the K content of the mantle well, it underesti-796 mates the continental crust concentration.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingnone given

    Nominal model runs result in net atmospheric drawdown over time, which is consistent with geochemical proxies.

    “Nominal model runs result in net atmospheric drawdown over time, which is consistent with geochemical proxies.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Findingnone given

    There are a number of controls on N history, including appearance of oxygenic photosynthesis, mantle cooling, and N in subduction zones.

    “There are a number of controls on N history, including appearance of oxygenic photosynthesis, mantle cooling, and N in subduction zones.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning

    The model with these parameters can reproduce the constraints of 1 PAN at 3.46 Ga and a 0.5 PAN atmosphere at 2.7 Ga but still result in a 1 PAN modern atmosphere.

    “The model with these parameters can 573 reproduce the constraints of 1 PAN at 3.46 Ga [Marty et al., 2013] and a 0.5 PAN atmo-574 sphere at 2.7 Ga [Som et al., 2012[Som et al., , 2016] ] but still result in a 1 PAN modern atmosphere.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Marty et al., 2013

      Not checked in the free run.

    • cites Som et al., 2012, 2016

      Not checked in the free run.

  • May combine two claims.

    Findingcitation

    The constant subduction efficiency run results in more N in the atmosphere than the mantle, contradicting estimates of N distribution on Earth today.

    “In addition, this run results in more N in the atmosphere than the mantle, contradicting estimates of N distribution on Earth today [Johnson and Goldblatt, 2015].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Johnson and Goldblatt, 2015

      Not checked in the free run.

  • Borderline on S3 (load-bearing), S4 (based): unclear from the text.

    Findingnone given

    Even in this case, there is still a 1.75 PAN atmosphere at 2.8 Ga, when oxygenic photosynthesis evolves.

    “Even in this case, there is still a 1.75 PAN atmosphere at 2.8 Ga, when oxygenic photo-576 synthesis evolves.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Findingnone given

    The atmosphere undergoes a dynamic evolution.

    “The atmosphere undergoes a dynamic evolution.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingreasoning

    On average, the atmosphere starts out with greater than modern mass, then decreases, likely due to the evolution of oxygenic photosynthesis.

    “On average, the atmosphere starts out with 620 greater than modern mass, then decreases, again likely due to the evolution of oxygenic”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingreasoning

    The main change in N-history occurs at the GOE, driven by increased weathering, nutrient supply, and enhanced biologic productivity.

    “Overall, the main change in N-history occurs at the GOE, driven 556 by increased weathering, nutrient supply, and enhanced biologic productivity.”
    Quote in the paperSubstantial claim

  • May combine two claims. The quote only partly states this claim.

    Findingreasoning

    The mantle N content increases with increasing total N content, but tends to saturate at about 4.5 PAN.

    “The mantle N content also increases with increasing total content, but tends to”
    • Also stated in: § 4 Conclusions · plain
      “The mantle tends to saturate at 4-4.75 PAN.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The initiation of plate tectonics does not affect the overall pattern, nor does it greatly affect the distribution of N between various reservoirs.

    “The initiation of plate tectonics does not affect the overall pattern, nor does it greatly effect the distribution of N between various reservoirs.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingreasoning

    The mantle is the dominant N carrier for total N budgets below 6-7 PAN, while the atmosphere is dominant at higher values.

    “The mantle is the dominant N carrier for total N budgets below 6-7 PAN, while the atmosphere is dominant at higher values.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Findingnone given

    The model has to increase hydrothermal circulation from 5 to 50 Sv, which limits PO4^3- and in turn limits atmospheric drawdown via N-fixing.

    “We also have to increase hydrothermal circulation from 5 to 50 Sv, which limits PO 3- 4 and 572 in turn limits atmospheric drawdown via N-fixing.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Mantle N for runs that result in a 1 PAN atmosphere average 4 PAN, but are variable.

    “Mantle N for runs that result in a 1 PAN atmosphere average 4 PAN, but are variable.”
    Quote in the paperNot a substantial claim

  • May combine two claims. The quote only partly states this claim.

    Findingown data

    Runs that result in a 1 PAN atmosphere start with a ~2 PAN atmosphere at 4.5 Ga and are drawn down in the late Archean.

    “Runs that result in a 1 PAN atmosphere start with a ∼ 2 PAN atmosphere at 4.5 Ga”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingnone given

    Deep sediments and continental crust increase as well.

    “Net drawdown occurs after oxygenic photosynthesis evolves, and deep sediments and continental crust increases as well.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingnone given

    The EarthN model reproduces the current distribution of N in the atmosphere (1 PAN) and the mantle (>3 PAN).

    “one that reproduces the current distribution of N in the atmosphere 429 (1 PAN) and the mantle (>3 PAN).”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The whole mantle equilibrated with the atmosphere during the magma ocean phase.

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    Biologic productivity and activity is the gate-keeper between the atmosphere and the solid Earth.

    “Biologic productivity and activity is the gate-keeper between the atmosphere and the solid Earth.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Crystalline N in altered crust is more likely to be carried into the mantle, whereas sedimentary N tends to return to the atmosphere at subduction zones.

    “to be carried into the mantle, whereas sedimentary N tends to return to the atmosphere at subduction zones [Fischer et al., 2002;Elkins et al., 2006;Halama et al., 2014].”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Fischer et al., 2002

      Not checked in the free run.

    • cites Elkins et al., 2006

      Not checked in the free run.

    • cites Halama et al., 2014

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Previous modelling efforts found little change (<1%) in atmospheric N2 over at least the Phanerozoic and possibly the majority of Earth history.

    “These studies found that there was little change (< 1%) in atmospheric N 2 over at least the Phanerozoic [Berner, 2006] and possibly the majority of Earth history [Zhang and Zindler, 1993].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Berner, 2006

      Not checked in the free run.

    • cites Zhang and Zindler, 1993

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation

    The solid Earth may hold the majority of the planet's N budget.

    “Recent work has challenged the notion that N is primarily an atmospheric species, and instead the solid Earth may actually hold the majority of the planet's N budget [Marty, 2012;Halliday, 2013;Johnson and Goldblatt, 2015;Barry and Hilton, 2016;Mallik et al., 2018].”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Marty, 2012

      Not checked in the free run.

    • cites Halliday, 2013

      Not checked in the free run.

    • cites Johnson and Goldblatt, 2015

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Previous Earth system models implicitly have biologic processing, but none so far explicitly model the behavior of organisms.

    “Previous Earth system models implicitly have biologic processing [e.g., Stüeken et al., 2016], but none so far actually explicitly model the behavior of organisms.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Stüeken et al., 2016

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    N and C may not behave similarly in subduction zones because N is likely found primarily as NH4+ geologically and C as organic C or CO3.

    “Sediment-only geologic N models also assume N and C behave similarly in subduction zones, which may not be true as N is likely found primarily as NH + 4 geologically and C as organic C or CO 2- 3 .”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    Previous whole-Earth modeling maintained a steady-state upper mantle by recycling surface N and lower mantle N, but this approach is incomplete because surface N is subducted as NH4+ and the mantle as a whole is likely not layered.

    “In addition, previous whole-Earth modeling [Tolstikhin and Marty, 1998] maintained a steady-state upper mantle, in terms of Nisotopes and concentration, by recycling of sedimentary and sea-water-sourced N from the surface and N from the lower mantle entrained in plumes.This approach is incomplete, as, again, surface N is subducted to the mantle as NH + 4 and it is likely that the mantle as a whole”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Tolstikhin and Marty, 1998

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    The proportion of subducted material driven off the slab is determined by mantle temperature: higher temperature means less material goes into the mantle, and lower temperature means more material goes into the mantle.

    “The proportion that is driven off the slab is determined by mantle temperature: higher temperature means less material goes into the mantle, and lower temperature means more material goes into the mantle.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Elkins et al., 2006

      Not checked in the free run.

    • cites Mitchell et al., 2010

      Not checked in the free run.

    • cites Zelenski et al., 2012

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Comparison to noble gases is not valid at subduction boundaries because N is mostly found as NH4+ in subducted sediments and oceanic crust.

    “Additionally, while comparison to noble gases is valid for outgassing of oxidized magmas [Libourel et al., 2003], this comparison is not valid at subduction boundaries, as N is mostly found as NH + 4 in subducted sediments [Bebout and Fogel, 1992] and oceanic crust [Busigny et al., 2011].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Bebout and Fogel, 1992

      Not checked in the free run.

    • cites Busigny et al., 2011

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Recent work using glacial tills as a proxy for upper continental crust through time suggests a secular increase in crustal N during the Precambrian.

    “For example, recent work using glacial tills as a proxy for upper continental crust through time suggest a secular increase in crustal N during the Precambrian [Johnson and Goldblatt, 2017].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Johnson and Goldblatt, 2017

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    There is not agreement on the exact level of O2 in the Proterozoic, but generally the maximum estimates are no greater than 10% of modern.

    “There is not agreement on the exact level of O 2 in the Proterozoic [Lyons et al., 2014;Planavsky et al., 2014;Reinhard et al., 2016;Zhang et al., 2016], but generally the maximum estimates are no greater than 10% of modern.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Lyons et al., 2014

      Not checked in the free run.

    • cites Planavsky et al., 2014

      Not checked in the free run.

    • cites Reinhard et al., 2016

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationreasoning

    Either subduction of N is not as efficient as described in the model and recycling into the mantle is less, or literature estimates of subduction and outgassing are too low.

    “This indicates that either subduction 475 of N is not as efficient as we describe, and recycling into the mantle is less, or literature 476 estimates of subduction and outgassing are too low.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationnone given

    Weathering and the Great Oxidation event cause atmospheric draw-down.

    “• Weathering and the Great Oxidation event cause atmospheric draw-down”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Study design and conductcitation

    Subducted fraction is a hyperbolic tangent fit to data from modern geothermal gradients and subducted fluxes at three modern subduction zones, and can vary between 0.1 and 1.

    “Subducted fraction is a hyperbolic tangent fit to the data from modern geothermal gradients and subducted fluxes at three modern subduction zones [Elkins et al., 2006;Mitchell et al., 2010;Zelenski et al., 2012], and can vary between 0.1 and 1:”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Elkins et al., 2006

      Not checked in the free run.

    • cites Mitchell et al., 2010

      Not checked in the free run.

    • cites Zelenski et al., 2012

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The Earth has gone through periods of orogenic activity and periods of quiescence with variable passive margin extent.

    “It is well known that the Earth has gone through periods of orogenic activity and periods of quiescence [e.g., Condie, 2013] with variable passive margin extent [Bradley, 2008], and these variations are not captured in our model.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Condie, 2013

      Not checked in the free run.

    • cites Bradley, 2008

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    The mantle likely has an enormous capacity for N, which likely exceeds its actual content at any given time.

    “As discussed in Li et al. [2013] and Johnson and Goldblatt [2015], the mantle likely has an enormous capacity for N, which likely exceeds its actual content at any given time.”
    • Also stated in: § 3.3 Investigating unknown nitrogen distribution: Monte Carlo simulations 585 · hedged
      “Previous work has estimated that 616 the mantle has an enormous capacity for N, and could possibly contain many 10s of PAN 617 [Li et al., 2013;Smith et al., 2014;Johnson and Goldblatt, 2015].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Li et al., 2013

      Not checked in the free run.

    • cites Smith et al., 2014

      Not checked in the free run.

    • cites Johnson and Goldblatt, 2015

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Navarro-González et al. [2001] suggests 2.1 × 10^10 mol yr^-1 could be fixed abiotically by lightning.

    “For example, Navarro-González et al. [2001] suggests 2.1 × 10 10 mol yr -1 could be fixed abiotically by lightning, while the minimum N-fixing we calculate is 2.9 × 10 11 mol yr -1 .”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Navarro-González et al. [2001]

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Redox changes with depth in the mantle have important effects on N solubility in mantle minerals.

    “There are redox changes with depth in the mantle [e.g.Frost and Mc-Cammon, 2008], which have important effects on N solubility in mantle minerals [Li et al., 2013[Li et al., , 2016]].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Frost and Mc-Cammon, 2008

      Not checked in the free run.

    • cites Li et al., 2013

      Not checked in the free run.

    • cites Li et al., 2016

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The EarthN model does not distinguish between the upper mantle, transition zone, and lower mantle.

    “In addition, we do not distinguish between the upper mantle, transition zone, and lower mantle.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationnone given

    Total, non-core N and plate tectonics exert strong control on atmospheric mass.

    “• Total, non-core N and plate tectonics exert strong control on atmospheric mass”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductreasoning

    The EarthN model includes both collision of marginal marine sediments and subduction zone processing fluxes, but they are only very general.

    “While we do have both of these fluxes in our model, they are only very general.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Atmospheric N is biologically fixed and then subsequently added to the continents either via collision of marginal marine sediments or incorporation from subduction zone processing, with a total crust N content of 0.5-0.67 PAN.

    “Atmospheric N is biologically fixed and then subsequently added to the continents either via collision of marginal marine sediments or incorporation from subduction zone processing, with a total crust N content of 0.5-0.67PAN.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Johnson and Goldblatt, 2017

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The EarthN model does not explicitly treat intra-plate or hot spot volcanism.

    “We note that there is no explicit treatment of intra-plate, or hot spot, volcanism in the model.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Nitrogen isotopes in granites indicate a biologic source, which could be from subducted material.

    “Nitrogen isotopes in granites indicate a biologic source [Boyd, 2001;Johnson and Goldblatt, 2017], which could be from subducted material.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Boyd, 2001

      Not checked in the free run.

    • cites Johnson and Goldblatt, 2017

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductcitation

    Redox, pH, and distribution between fluids and melt may have effects on subducted fraction that are not considered in the model.

    “While temperature is assumed to have a first-order effect in our model, redox [Libourel et al., 2003;Li et al., 2016], pH [Mikhail and Sverjensky, 2014], and distribution between fluids and melt [Li et al., 2015;Mallik et al., 2018], may all have effects which are not considered here.”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Libourel et al., 2003

      Not checked in the free run.

    • cites Mikhail and Sverjensky, 2014

      Not checked in the free run.

    • cites Mallik et al., 2018

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Studies have shown that redox, temperature/pressure, distribution of N between fluid and melt, and pH also exert control over N speciation and retention in the mantle.

    “Studies have shown that redox [Li et al., 2013], temperature/pressure [Li and Keppler, 2014], distribution of N between fluid and melt [Mallik et al., 2018], and pH [Mikhail and Sverjensky, 2014] also exert control over N speciation and retention in the mantle.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Li et al., 2013

      Not checked in the free run.

    • cites Li and Keppler, 2014

      Not checked in the free run.

    • cites Mallik et al., 2018

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    There is a discord between modern geochemical data suggesting net ingassing of the atmosphere through time and either net outgassing or atmospheric stability since the Archean.

    “As mentioned in the introduction, there is a discord between modern geochecmi-559 cal data suggesting net ingassing of the atmosphere through time [Busigny et al., 2011; 560 Nishizawa et al., 2007;Barry and Hilton, 2016] and either net outgassing [Som et al., 2012, 561 2016] or atmospheric stability since the Archean [Marty et al., 2013].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Busigny et al., 2011

      Not checked in the free run.

    • cites Nishizawa et al., 2007

      Not checked in the free run.

    • cites Barry and Hilton, 2016

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The EarthN model does not model a specific increase in productivity due to the evolution of eukaryotes.

    “We do not, however, model a specific increase in productivity due to the evolution of eukaryotes, which might be expected to enhance biologic N-cycling [e.g., Zerkle and Mikhail, 2017, and references therein].”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    Higher K-content in the crust would lead to more 40Ar in the crust, through storage after radioactive decay of 40K, and would then lower the atmospheric Ar-ratio.

    “Higher K-content in the crust would lead to more 40 Ar in the 793 crust, through storage after radioactive decay of 40 K, and would then lower the atmospheric 794 Ar-ratio.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    Lower atmospheric mass in the past cannot be specifically ruled out by the model output, but such lower mass would present a number of interesting implications.

    “Lower atmospheric mass in the past cannot be specifically ruled out by our model 578 output, but such lower mass would present a number of interesting implications.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    Net subduction and outgassing at mid-ocean ridges tend to balance each other, while N-fixing is limited by PO4^3- availability.

    “This is because net subduction and outgassing at mid-ocean ridges tend to balance each other, while N-fixing is limited by PO 3- 4 availability.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Study design and conductnone given

    Weathering is simply proportional to concentration in the model, and does not take into account either differences in weathering due to biologic activity or continental growth over time.

    “Weathering is simply proportional to concen-797 tration in the model, and does not take into account either differences in weathering due 798 to biologic activity or continental growth over time.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    It is possible that the slight overestimate of atmospheric 40Ar/36Ar is due in part to the model underestimating K concentration in the continental crust.

    “It is possible that 791 this slight overestimate is due in part to the model underestimating K concentration in the 792 continental crust (Fig. C.1).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The interaction of these different factors in geologic evolution could have had a large effect on N cycling over Earth history.

    “The interaction of these different factors in geologic evolution could have had a large effect on N cycling over Earth history [Mikhail and Howell, 2016].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Mikhail and Howell, 2016

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    The rate at which organisms can fix N is not enough to outpace overall outgassing, so at higher total N budgets, N accumulates in the atmosphere.

    “That is, the rate at which organisms can fix N is not enough to outpace overall outgassing, thus at higher total N budgets, N accumulates in the atmosphere.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The EarthN model does not consider the effects of continental lithospheric roots or cratonic mass, which could serve to store K for long periods during Earth history.

    “In addition, we do not consider the effects of continental lithospheric 801 roots or cratonic mass, which could serve to store K for long periods during Earth history.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given

    This behavior also depends on how much temperature actually controls N volatilization at subduction zones.

    “This behavior also depends on how much temperature actually controls N volatilization at subduction zones.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Study design and conductnone given

    The EarthN model does not thoroughly parameterize mantle evolution.

    “In addition, the EarthN model does not thoroughly parameterize mantle evolution”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationnone given

    If Earth had less than a one PAN atmosphere, there would need to be 10^-2.2 bars of CO2, and even more with less.

    “If the Earth had less than a 582 one PAN atmosphere, there would need to be 10 -2.2 bars of CO 2 , and even more with less”
    Quote in the paperNot a substantial claim
65 of 65

  • The authors state this as an assumption.

    The N:P ratio in the ocean will always move towards Redfield (16:1).

    “The proportion of F oldN to F newN depends, in part, on the N:P ratio, which we assume will always move towards Redfield (i.e., 16:1).”

  • The authors state this as an assumption.

    Productivity was 1000 times less efficient before the evolution of oxygenic photosynthesis.

    “We also assume productivity (P) was 1000 times less efficient before the evolution of oxygenic photosynthesis:”

  • The authors state this as an assumption.

    Nitrogen remineralization and burial occur in Redfield ratio (16:1) compared to phosphate.

    “Nitrogen remineralization and burial is assumed to be in Redfield ratio (i.e.,16:1) compared to PO 3- 4 .”

  • The authors state this as an assumption.

    Subducted species instantly homogenize into the mantle (there are no separate mantle domains).

    “It is assumed that they instantly homogenize into the mantle (i.e., there are no separate mantle domains).”

  • The authors state this as an assumption.

    Half of N released from subducted materials is outgassed at arcs and half is incorporated into the continental crust (f_Ncgarc = 0.5).

    “For N, f Ncgarc is set to 0.5.That is, half of N released from subducted materials is outgassed at arcs and half is incorporated into the continental crust.This value, 0.5, is an assumption in our model.”

  • The authors state this as an assumption.

    90% of all species are partitioned to the melt during partial melting, with 10% remaining in the residual.

    “We assume 90% of all species are partitioned to the melt during partial melting (K dist ), with 10% remaining in the residual.”

  • The authors state this as an assumption.

    Temperature has a first-order effect on the proportion of subducted material driven off the slab in the model.

    “While temperature is assumed to have a first-order effect in our model, redox [Libourel et al., 2003;Li et al., 2016], pH [Mikhail and Sverjensky, 2014], and distribution between fluids and melt [Li et al., 2015;Mallik et al., 2018], may all have effects which are not considered here.”

  • The authors state this as an assumption.

    Biologic N-fixing could operate throughout the model run.

    “instead assume biologic N-fixing could operate throughout the model run”

  • The authors state this as an assumption.

    The entire mantle experienced a magma ocean phase.

    “We assume the entire mantle experienced 425 a magma ocean phase.”

  • The authors state this as an assumption.

    The whole mantle equilibrated with the atmosphere during the magma ocean phase.

    “This assumes the whole mantle equilibrated during the atmosphere during the magma ocean phase.”
10 of 10

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • A model can be constructed where pN2 declines after the GOE if burial of organic nitrogen increased.

    “On the other hand, a model can be constructed where pN2 declines after the GOE if burial of organic nitrogen increased (142).”

    From The Archean atmosphere (2020) · cites this paper as [142]

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Atmospheric argon equation omits weathering input

    Major

    Weathered argon is said to enter the atmosphere, but the stated atmospheric equation for both argon isotopes includes only air-sea exchange and arc outgassing.

  • Continental-growth equation sends argon into the crust

    Major

    The text says all argon released from subducted material is outgassed, whereas equation (36) assigns both argon isotopes a flux into the continental crust.

  • Mantle outgassing formula uses 10% of crust production instead of ten times

    Major

    The text says the mantle mass involved in crust genesis is ten times the crust produced, but equation (40) multiplies crust production by the partial-melt fraction of 10%. The two prescriptions differ by a factor of 100 before the partitioning factor is applied.

  • Nitrification oxygen half-saturation has conflicting values

    Major

    The nitrification description assigns the oxygen half-saturation constant a value of 20 μM, whereas Table 2 gives 283 nM for the same constant.

  • Nominal run has two different total nitrogen budgets

    Major

    The nominal starting conditions specify 4.8 PAN, while the appendix says 4.5 PAN was chosen as the total budget for the nominal run.

  • Production timescale is listed with inverse-time units

    Minor

    The text defines τ prod as a timescale of 0.5 years, but Table 2 gives its units as yr−1. These are incompatible units for the same parameter.

  • Mantle saturation is reported as both 4.5 and 3 PAN

    Minor

    The discussion places mantle saturation at 4.5 PAN, but the Figure 9 caption describes the mantle saturating at 3 PAN.

7 of 7

Cites

Flagged first, then by citations

Research works printed but not linked: 4

  1. 10.2138/am-2015-5363 · DOI
  2. Delwiche C., 1977, Energy relations in the global nitrogen cycle, Ambio, 106
  3. Garcia H., 2014, Dissolved inorganic nutrients (phosphate, nitrate, silicate), World Ocean Atlas, 4, 25
  4. Gruber N., 2008, The marine nitrogen cycle: Overview and challenges, Nitrogen in the Marine Environment, 2, 1

Cited by

Sorted by citations

Related

Authors
Johnson, B. W., & Goldblatt, C.
Affiliations
University of Colorado Boulder (US)
Corresponding author
Johnson, Benjamin W.
ORCID
Venue
Geochemistry, Geophysics, Geosystems
Publisher
American Geophysical Union (AGU)
Published
2018-08
Volume
19
Issue
8
Pages
2516-2542
ISSN
1525-2027 (ISSN-L)
DOI
10.1029/2017gc007392
OpenAlex
W2798926696
Semantic Scholar
e383f39f8d6442339308aff0a0bdd21333be6fb3
Cited by
51
References
83
Citations by year
2026: 3 · 2025: 8 · 2024: 7 · 2023: 7 · 2022: 4 · 2021: 7 · 2020: 8 · 2019: 4 · 2018: 2
FWCI
3.86
Type
journal article
Language
en
Open access
Licence
Locations
  • Geochemistry Geophysics Geosystems (publishedVersion)
  • EarthArXiv (California Digital Library) (submittedVersion)
  • arXiv (Cornell University) (submittedVersion)
  • CU Scholar (University of Colorado Boulder) (submittedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion)
  • OSF Preprints (OSF Preprints) (submittedVersion)
  • arXiv (Cornell University)
Funders
  • National Science Foundation (EAR ‐ 1725784)
  • Natural Sciences and Engineering Research Council of Canada
Topics
  • Physical Sciences › Earth and Planetary Sciences › Paleontology › Paleontology and Stratigraphy of Fossils
  • Physical Sciences › Earth and Planetary Sciences › Atmospheric Science › Earth Systems and Cosmic Evolution
  • Physical Sciences › Earth and Planetary Sciences › Geophysics › Geological and Geochemical Analysis
Keywords
nitrogen cycling, Earth system modeling, atmospheric nitrogen, mantle cooling, oxygen cycle, nitrogen balance, weathering

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-10.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-10.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

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