Rates of fixation by lightning of carbon and nitrogen in possible primitive atmospheres

Chameides, W. L.; Walker, James C. G.

doi:10.1007/bf00931483

Cited by 141 publications

(86 citation statements)

References 30 publications

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“…Theoretically-predicted yields of HCN and NO for lightning-produced shocks in a one-bar atmosphere. The N z partial pressure is 0.9 bar; the rest of the atmosphere varies in composition from 0 2 tO CH 4 (after Chameides and Walker, 1981). heating in lightning or impacts (Chameides and Walker, 1981;Fegley et al, 1986;Stribling and Miller, 1987). If methane was present at the part per million level or higher, HCN could also have been produced by reactions of ionosphericallyderived N atoms with the by-products of methane photolysis (Zahnle, 1986).…”

Section: B Effect Of Co Reactions In the Oceanmentioning

confidence: 98%

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Bolide impacts and the oxidation state of carbon in the Earth's early atmosphere

Kasting

1990

Origins Life Evol Biosphere

253

170

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A one-dimensional photochemical model was used to examine the effect of bolide impacts on the oxidation state of Earth's primitive atmosphere. The impact rate should have been high prior to 3.8 Ga before present, based on evidence derived from the Moon. Impacts of comets or carbonaceous asteroids should have enhanced the atmospheric CO/CO2 ratio by bringing in CO ice and/or organic carbon that can be oxidized to CO in the impact plume. Ordinary chondritic impactors would contain elemental iron that could have reacted with ambient CO2 to give CO. Nitric oxide (NO) should also have been produced by reaction between ambient CO2 and N2 in the hot impact plumes. High NO concentrations increase the atmospheric CO/CO2 ratio by increasing the rainout rate of oxidized gases. According to the model, atmospheric CO/CO2 ratios of unity or greater are possible during the first several hundred million years of Earth's history, provided that dissolved CO was not rapidly oxidized to bicarbonate in the ocean. Specifically, high atmospheric CO/CO2 ratios are possible if either: (1) the climate was cool (like today's climate), so that hydration of dissolved CO to formate was slow, or (2) the formate formed from CO was efficiently converted into volatile, reduced carbon compounds, such as methane. A high atmospheric CO/CO2 ratio may have helped to facilitate prebiotic synthesis by enhancing the production rates of hydrogen cyanide and formaldehyde. Formaldehyde may have been produced even more efficiently by photochemical reduction of bicarbonate and formate in Fe(++)-rich surface waters.

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Section: B Effect Of Co Reactions In the Oceanmentioning

confidence: 98%

“…NO PRODUCTION RATE NO would also have been produced in impacts by shock heating of ambient N2 and CO2 (Chameides and Walker, 1981;Fegley et al, 1986). This process can be simulated with various degrees of complexity.…”

Section: Production Of Co and No By Impactsmentioning

confidence: 99%

Bolide impacts and the oxidation state of carbon in the Earth's early atmosphere

Kasting

1990

Origins Life Evol Biosphere

253

170

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“…Several workers have shown that lightning (Chameides and Walker 1981) or bolide impacts (Fegley et al 1986;Chyba and Sagan 1992) can produce modest amounts of HCN from strong shock heating in CO-N 2 -H 2 O atmospheres. Yields are about three orders of magnitude larger in methane-ammonia atmospheres, and three orders smaller if the atmosphere is mostly CO 2 rather than CO.…”

Section: After the Moon-forming Impactmentioning

confidence: 99%

Earth's Earliest Atmospheres

Zahnle¹,

Schaefer²,

Fegley³

2010

Cold Spring Harbor Perspectives in Biology

233

157

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Earth is the one known example of an inhabited planet and to current knowledge the likeliest site of the one known origin of life. Here we discuss the origin of Earth's atmosphere and ocean and some of the environmental conditions of the early Earth as they may relate to the origin of life. A key punctuating event in the narrative is the Moon-forming impact, partly because it made Earth for a short time absolutely uninhabitable, and partly because it sets the boundary conditions for Earth's subsequent evolution. If life began on Earth, as opposed to having migrated here, it would have done so after the Moon-forming impact. What took place before the Moon formed determined the bulk properties of the Earth and probably determined the overall compositions and sizes of its atmospheres and oceans. What took place afterward animated these materials. One interesting consequence of the Moon-forming impact is that the mantle is devolatized, so that the volatiles subsequently fell out in a kind of condensation sequence. This ensures that the volatiles were concentrated toward the surface so that, for example, the oceans were likely salty from the start. We also point out that an atmosphere generated by impact degassing would tend to have a composition reflective of the impacting bodies (rather than the mantle), and these are almost without exception strongly reducing and volatile-rich. A consequence is that, although CO-or methane-rich atmospheres are not necessarily stable as steady states, they are quite likely to have existed as long-lived transients, many times. With CO comes abundant chemical energy in a metastable package, and with methane comes hydrogen cyanide and ammonia as important albeit less abundant gases.

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“…Several workers have shown that lightning (Chameides and Walker 1981) or bolide impacts (Fegley et al 1986, Fegley and Prinn 1989, Chyba and Sagan 1992 have a shielding effect that protects the methane and ammonia from rapid destruction by UV (Sagan and Chyba 1997). Titan's atmosphere is often regarded as chemically analogous to early Earth but the comparison is strained because its atmosphere is too cold for oxygen (the element)…”

Section: After the Moon-forming Impactmentioning

confidence: 99%

Earth's Earliest Atmosphere

Zahnle

2006

Elements

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Earth is the one known example of an inhabited planet and to current knowledge the likeliest site of the one known origin of life. Here we discuss the origin of Earth's atmosphere and ocean and some of the environmental conditions of the early Earth as they may relate to the origin of life. A key punctuating event in the narrative is the Moon-forming impact, partly because it made Earth for a short time absolutely uninhabitable, and partly because it sets the boundary conditions for Earth's subsequent evolution. If life began on Earth, as opposed to having migrated here, it would have done so after the Moon-forming impact. What took place before the Moon formed determined the bulk properties of the Earth and probably determined the overall compositions and sizes of its atmospheres and oceans. What took place afterward animated these materials.One interesting consequence of the Moon-forming impact is that the mantle is devolatized, so that the volatiles subsequently fall out in a kind of condensation sequence. This ensures that the volatiles are concentrated toward the surface so that, for example, the oceans were likely salty from the start. We also point out that an atmosphere generated by impact degassing would tend to have a composition reflective of the impacting bodies (rather than the mantle), and these are almost without exception strongly reducing and volatile-rich. A consequence is that, although CO-or methane-rich atmospheres are not necessarily stable as steady states, they are quite likely to have existed as long-lived transients, many times. With CO comes abundant chemical energy in a metastable package, and with methane come hydrogen cyanide and ammonia as important albeit less abundant gases.

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Rates of fixation by lightning of carbon and nitrogen in possible primitive atmospheres

Cited by 141 publications

References 30 publications

Bolide impacts and the oxidation state of carbon in the Earth's early atmosphere

Bolide impacts and the oxidation state of carbon in the Earth's early atmosphere

Earth's Earliest Atmospheres

Earth's Earliest Atmosphere

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