TY - JOUR
T1 - Revisiting HCN formation in Earth's early atmosphere
AU - Tian, Feng
AU - Kasting, J. F.
AU - Zahnle, K.
N1 - Funding Information:
We thank 3 anonymous reviewers for their constructive comments. F.T. thanks Dr. R.V. Yelle for helpful discussions on HCN chemistry in Titan's atmosphere and Dr. V. Veronique for help with HCN photolysis cross sections. F.T. and O.B.T. are partially supported by NASA Award# NNX10AR17G .
PY - 2011/8/15
Y1 - 2011/8/15
N2 - Using a new photochemical model, the HCN chemistry in Earth's early atmosphere is revisited. We find that HCN production in a CH4-rich early atmosphere could have been efficient, similar to the results of a previous study (Zahnle, 1986). For an assumed CH4 mixing ratio of 1000ppmv, HCN surface deposition increases from 2×109cm-2s-1 at fCO2=3% to more than 1×1010cm-2s-1 (30Tg/yr) at fCO2=0.3% and 1%. These conditions may well have applied throughout much of the Archean eon, 3.8-2.5Ga. Prior to the origin of life and the advent of methanogens, HCN production rates would likely have been at 1×107cm-2s-1 or lower, thereby providing a modest source of HCN for prebiotic synthesis.
AB - Using a new photochemical model, the HCN chemistry in Earth's early atmosphere is revisited. We find that HCN production in a CH4-rich early atmosphere could have been efficient, similar to the results of a previous study (Zahnle, 1986). For an assumed CH4 mixing ratio of 1000ppmv, HCN surface deposition increases from 2×109cm-2s-1 at fCO2=3% to more than 1×1010cm-2s-1 (30Tg/yr) at fCO2=0.3% and 1%. These conditions may well have applied throughout much of the Archean eon, 3.8-2.5Ga. Prior to the origin of life and the advent of methanogens, HCN production rates would likely have been at 1×107cm-2s-1 or lower, thereby providing a modest source of HCN for prebiotic synthesis.
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U2 - 10.1016/j.epsl.2011.06.011
DO - 10.1016/j.epsl.2011.06.011
M3 - Article
AN - SCOPUS:79960557435
SN - 0012-821X
VL - 308
SP - 417
EP - 423
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
IS - 3-4
ER -