Ferrocyanide survival under near ultraviolet (300–400 nm) irradiation on early Earth

Todd, Zoe R.; Lozano, Gabriella G.; Kufner, Corinna L.; Sasselov, Dimitar; Catling, David C.

doi:10.1016/j.gca.2022.08.012

Cited by 5 publications

(7 citation statements)

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“…Once the H 2 escapes, the surface temperature would drop to ∼300 K (Figure 6), and over longer timescales, the carbonate-silicate cycle might settle on even colder climates because impact ejecta promotes CO 2 sequestration (Kadoya et al 2020). In this cold climate, cyanide stockpiled into salts could be released as HCN or CN − into water bodies on land because of rehydration, volcanic or impact heating (Patel et al 2015;Sasselov et al 2020), or UV exposure (Todd et al 2022). Liberation of cyanide could enable the prebiotic schemes that make RNA.…”

Section: Origin-of-life Setting and Stockpiling Of Cyanidesmentioning

confidence: 99%

Origin-of-life Molecules in the Atmosphere after Big Impacts on the Early Earth

Wogan,

Catling,

Zahnle

et al. 2023

Planet. Sci. J.

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The origin of life on Earth would benefit from a prebiotic atmosphere that produced nitriles, like HCN, which enable ribonucleotide synthesis. However, geochemical evidence suggests that Hadean air was relatively oxidizing with negligible photochemical production of prebiotic molecules. These paradoxes are resolved by iron-rich asteroid impacts that transiently reduced the entire atmosphere, allowing nitriles to form in subsequent photochemistry. Here we investigate impact-generated reducing atmospheres using new time-dependent, coupled atmospheric chemistry and climate models that account for gas-phase reactions and surface catalysis. The resulting H2-, CH4-, and NH3-rich atmospheres persist for millions of years, until the hydrogen escapes to space. The HCN and HCCCN production and rainout to the surface can reach 109 molecules cm−2 s−1 in hazy atmospheres with a mole ratio of CH4/CO2 > 0.1. Smaller CH4/CO2 ratios produce HCN rainout rates of <105 molecules cm−2 s−1 and negligible HCCCN. The minimum impactor mass that creates atmospheric CH4/CO2 > 0.1 is 4 × 1020–5 × 1021 kg (570–1330 km diameter), depending on how efficiently iron reacts with a steam atmosphere, the extent of atmospheric equilibration with an impact-induced melt pond, and the surface area of nickel that catalyzes CH4 production. Alternatively, if steam permeates and deeply oxidizes the crust, impactors of ∼1020 kg could be effective. Atmospheres with copious nitriles have >360 K surface temperatures, perhaps posing a challenge for RNA longevity, although cloud albedo can produce cooler climates. Regardless, postimpact cyanide can be stockpiled and used in prebiotic schemes after hydrogen has escaped to space.

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Section: Origin-of-life Setting and Stockpiling Of Cyanidesmentioning

confidence: 99%

Origin-of-life Molecules in the Atmosphere after Big Impacts on the Early Earth

Wogan,

Catling,

Zahnle

et al. 2023

Planet. Sci. J.

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“…Our model assumes that the volume of the lake is not changing and that ferrocyanide does not have the opportunity to precipitate out of solution. In cases where evaporation occurs, ferrocyanide can precipitate as various salts and potentially accumulate and stockpile in this manner (see Toner and Catling 26 and Sasselov et al 23 for further discussion). In the planetary scenario, it is likely that there will be depth-dependent variations in the concentrations of ferrocyanide as cyanide rains out to form ferrocyanide, UV light is acting to degrade ferrocyanide near the surface, further reactions are occurring in the aqueous medium, and precipitation is occurring to allow complexes to come out of solution.…”

Section: ■ Resultsmentioning

confidence: 99%

“…Ferrocyanide can store and stockpile cyanide, 23 which can then be liberated later through, e.g., thermal processing. 4 In addition, ferrocyanide has been shown to be useful for the prebiotic synthesis of the building blocks of life via reductive homologation of hydrogen cyanide.…”

Section: ■ Introductionmentioning

confidence: 99%

Favorable Environments for the Formation of Ferrocyanide, a Potentially Critical Reagent for Origins of Life

Todd,

Wogan,

Catling

2024

ACS Earth Space Chem.

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Cyanide and its derivatives play important roles in prebiotic chemistry through a variety of possible mechanisms. In particular, cyanide has been shown to allow for the synthesis of ribonucleotides and amino acids. Although dissolved hydrogen cyanide can be lost as a gas or undergo hydrolysis reactions, cyanide can also potentially be stored and stockpiled as ferrocyanide (Fe(CN) 6 −4), which is more stable. Furthermore, ferrocyanide aids in some prebiotic synthetic reactions. Here, we investigate the formation rates and yields of ferrocyanide as a function of various environmental parameters, such as the pH, temperature, and concentration. We find that ferrocyanide formation rates and yields are optimal at slightly alkaline conditions (pH 8−9) and moderate temperatures (≈20−30 °C). Given the wide range of possible lake environments likely available on early Earth, our results help to constrain the environmental conditions that would favor cyanide-and ferrocyanide-based prebiotic chemistries. We construct lake box models and find that ferrocyanide may be able to form and reach significant concentrations for prebiotic chemistry on the time scale of years under favorable conditions.

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“…Meanwhile, strongly reducing atmospheres induced by large and more reducing impactors might favor the accumulation of critical bases for the synthesis reactions. Water bodies with high evaporation rates on land could also favor molecular condensation ( Pérez-Fernández et al, 2022 ), but would be confronted with photodegradation processes ( Cleaves, 2008 ; Todd et al, 2022 ).…”

Section: Discussionmentioning

confidence: 99%

Evaluating the abiotic synthesis potential and the stability of building blocks of life beneath an impact-induced steam atmosphere

Zhang

Jiang

et al. 2023

Front. Microbiol.

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A prerequisite for prebioticIf applicable, check your taxonomy and/or nomenclature carefully to avoid any errors that may invalidate it. chemistry is the accumulation of critical building blocks of life. Some studies argue that more frequent impact events on the primitive Earth could have induced a more reducing steam atmosphere and thus favor widespread and more efficient synthesis of life building blocks. However, elevated temperature is also proposed to threaten the stability of organics and whether life building blocks could accumulate to appreciable levels in the reducing yet hot surface seawater beneath the steam atmosphere is still poorly examined. Here, we used a thermodynamic tool to examine the synthesis affinity of various life building blocks using inorganic gasses as reactants at elevated temperatures and corresponding steam pressures relevant with the steam-seawater interface. Our calculations show that although the synthesis affinity of all life building blocks decreases when temperature increases, many organics, including methane, methanol, and carboxylic acids, have positive synthesis affinity over a wide range of temperatures, implying that these species were favorable to form (>10–6 molal) in the surface seawater. However, cyanide and formaldehyde have overall negative affinities, suggesting that these critical compounds would tend to undergo hydrolysis in the surface seawaters. Most of the 18 investigated amino acids have positive affinities at temperature <220°C and their synthesis affinity increases under more alkaline conditions. Sugars, ribose, and nucleobases have overall negative synthesis affinities at the investigated range of temperatures. Synthesis affinities are shown to be sensitive to the hydrogen fugacity. Higher hydrogen fugacity (in equilibrium with FQI or IW) favors the synthesis and accumulation of nearly all the investigated compounds, except for HCN and its derivate products. In summary, our results suggest that reducing conditions induced by primitive impacts could indeed favor the synthesis/accumulation of some life building blocks, but some critical species, particularly HCN and nucleosides, were still unfavorable to accumulate to appreciable levels. Our results can provide helpful guidance for future efforts to search for or understand the stability of biomolecules on other planets like Mars and icy moons. We advocate examining craters formed by more reducing impactors to look for the preservation of prebiotic materials.

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Ferrocyanide survival under near ultraviolet (300–400 nm) irradiation on early Earth

Cited by 5 publications

References 47 publications

Origin-of-life Molecules in the Atmosphere after Big Impacts on the Early Earth

Origin-of-life Molecules in the Atmosphere after Big Impacts on the Early Earth

Favorable Environments for the Formation of Ferrocyanide, a Potentially Critical Reagent for Origins of Life

Evaluating the abiotic synthesis potential and the stability of building blocks of life beneath an impact-induced steam atmosphere

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