CoChat
Sign Up
Cited by 277Atmospheric chemistry and aerosolsPaleontology and Stratigraphy of FossilsAstro and Planetary Science

The DOI matches its Crossref record; 122 of the 123 references it cites were found in a registry or an index.

Photochemistry of methane and the formation of hydrocyanic acid (HCN) in the Earth's early atmosphere

Zahnle, Kevin J.·1986·Journal of Geophysical Research: Atmospheres
DOI 10.1029/jd091id02p02819
Open this paper in CoChat — free account

Abstract

The photochemistries of methane and HCN are discussed in the context of the primitive terrestrial atmosphere, using a detailed numerical model. In the absence of abundant O 2, absorption of solar EUV (λ < 1023Å) by N 2 provides a large thermospheric source of atomic nitrogen. Methane is oxidized cleanly and efficiently, provided CO 2 is more abundant than CH 4. Otherwise, a large fraction of the methane present is polymerized, forming alkanes in the troposphere and polyacetylenes and nitriles in the upper atmosphere. The combination of low O 2, high N 2, and moderately high levels of CO 2 would have made the ancient terrestrial atmosphere a favorable environment for the production of HCN from CH 4. Once formed, HCN is rather long‐lived; it is removed from the atmosphere either by direct photodissociation at Ly α (∼100 years) or by rainfall (∼10 years). Chemical loss would have been unimportant. Owing to its stability, transport of HCN from the top to the bottom of the atmosphere can be efficient; nevertheless, our results are sensitive to the assumed eddy diffusion profile. For small amounts of methane a small constant fraction of order 0.1% to 1% of the carbon in the methane is returned to the surface as hydrocyanic acid rain. For larger methane sources exceeding a critical value of order 10 11 molecules cm−2 s−1 (corresponding to ƒ(CH 4) of order 10−4–10−3), rainout of HCN increases abruptly to more than 10% of the carbon supplied as methane, limited by the primary production of N. Under favorable conditions, hydrolysis of HCN could have supported atmospheric NH 3 mixing ratios approaching 1 ppm.

Overview

Integrity signals

Registry

Crossref · 10.1029/jd091id02p02819

Cites

122 of 122 references verified0 citation errors · 0 not checkable

Statistics

Recomputing p-values needs the paper’s full text.

Verification

Claims the paper makes

This paper’s full text isn’t openly available, so its claims and self-check weren’t run. The registry and citation checks still apply.

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?

Citations

Cites

Flagged first, then by citations

1 of the 123 references couldn’t be matched to a known paper.

Research works printed but not linked: 6

  1. Barassin J., 1974, Etude cinètique des réaction entre l'oxygèn et les dérivés chlores du methane, Bull. Soc. Chim. France, 1
  2. Chang S., 1983, Origin and Evolution of Earth's Earliest Biosphere
  3. Huebner W. F., 1980, A model of comet comae, Astrophys. J., 238, 763
  4. Oró J., 1981, Cyanide in Biology
  5. Shu F., 1982, The Physical Universe
  6. Walker J. C. G., 1977, Evolution of the Atmosphere

Cited by

Sorted by citations

See all 277

Related

See all

Metadata

Authors
Zahnle, K. J.
Corresponding author
Zahnle, Kevin J.
ORCID
Zahnle, Kevin J.
Venue
Journal of Geophysical Research: Atmospheres
Publisher
American Geophysical Union (AGU)
Published
1986-02-20
Volume
91
Issue
D2
Pages
2819-2834
ISSN
0148-0227 (ISSN-L)
DOI
10.1029/jd091id02p02819
OpenAlex
W1965198394
Cited by
276
References
123
Citations by year
2026: 10 · 2025: 18 · 2024: 13 · 2023: 7 · 2022: 18 · 2021: 10 · 2020: 16 · 2019: 20 · 2018: 17 · 2017: 7 · 2016: 11 · 2015: 11 · 2014: 6 · 2013: 8 · 2012: 4
FWCI
4.19
Type
journal article
Language
en
Open access
closed
Licence
onlinelibrary.wiley.com/termsAndConditions#vor (vor, 9710 d)
Locations
Journal of Geophysical Research Atmospheres (publishedVersion)
Topics
  • Physical Sciences › Earth and Planetary Sciences › Atmospheric Science › Atmospheric chemistry and aerosols
  • Physical Sciences › Earth and Planetary Sciences › Paleontology › Paleontology and Stratigraphy of Fossils
  • Physical Sciences › Earth and Planetary Sciences › Space and Planetary Science › Astro and Planetary Science
Keywords
methane photochemistry, hydrogen cyanide, early Earth atmosphere, atomic nitrogen, methane oxidation, polyacetylene, nitriles, atmospheric transport, turbulent diffusion, ammonia, carbon cycle, CO2 abundance

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.

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.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review