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Wu X, Zhu J, He H, Konhauser KO, Li Y. Comments on "was hydrogen peroxide present before the arrival of oxygenic photosynthesis? The important role of iron(II) in the archean ocean". Redox Biol 2024; 71:103111. [PMID: 38521703 PMCID: PMC11313173 DOI: 10.1016/j.redox.2024.103111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Accepted: 02/29/2024] [Indexed: 03/25/2024] Open
Abstract
Recent research has hypothesized that hydrogen peroxide (H2O2) may have emerged from abiotic geochemical processes during the Archean eon (4.0-2.5 Ga), stimulating the evolution of an enzymatic antioxidant system in early life. This eventually led to the evolution of cyanobacteria, and in turn, the accumulation of oxygen on Earth. In the latest issue of Redox Biology, Koppenol and Sies (vol. 29, no. 103012, 2024) argued against this hypothesis and suggested instead that early organisms would not have been exposed to H2O2 due to its short half-life in the ferruginous oceans of the Archean. We find these arguments to be factually incomplete because they do not consider that freshwater or some coastal marine environments during the Archean could indeed have led to H2O2 generation and accumulation. In these environments, abiotic oxidants could have interacted with early life, thus steering its evolutionary course.
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Affiliation(s)
- Xiao Wu
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (CAS), Guangzhou, 510640, China; CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China
| | - Jianxi Zhu
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (CAS), Guangzhou, 510640, China; CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China.
| | - Hongping He
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (CAS), Guangzhou, 510640, China; CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Kurt O Konhauser
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, T6G 2E3, Canada
| | - Yiliang Li
- Department of Earth Sciences, The University of Hong Kong, Hong Kong, 999077, China.
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2
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Zhi Y, Guo Q, Xie J, Hu J, Tian SX. Direct production of molecular oxygen from carbon dioxide and helium ion collisions. Commun Chem 2023; 6:267. [PMID: 38057399 DOI: 10.1038/s42004-023-01074-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 11/22/2023] [Indexed: 12/08/2023] Open
Abstract
The prebiotic mechanism to produce molecular oxygen (O2) in carbon dioxide (CO2)-rich planetary atmospheres is of great importance in understanding astrochemical reactions and is potentially relevant to the origin of life on Earth. Here, we demonstrate that, aside from the direct productions of O2 by photodissociation and dissociative electron attachment, the low-energy ion-molecule reaction between cationic helium in solar winds and molecular CO2 is a noticeable mechanism. Branching ratios of the reaction channels are determined, and their absolute cross-sections are estimated accordingly. The present findings represent a further, indispensable step towards fully understanding the origins of atmospheric O2.
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Affiliation(s)
- Yaya Zhi
- Department of Chemical Physics, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), University of Science and Technology of China, 230026, Hefei, China
| | - Qiang Guo
- Department of Chemical Physics, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), University of Science and Technology of China, 230026, Hefei, China
| | - Jingchen Xie
- Department of Chemical Physics, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), University of Science and Technology of China, 230026, Hefei, China
| | - Jie Hu
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 230026, Hefei, China.
| | - Shan Xi Tian
- Department of Chemical Physics, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), University of Science and Technology of China, 230026, Hefei, China.
- Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, 230026, Hefei, China.
- Hefei National Laboratory, University of Science and Technology of China, 230088, Hefei, China.
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3
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Chang Y, Fu Y, Chen Z, Luo Z, Zhao Y, Li Z, Zhang W, Wu G, Fu B, Zhang DH, Ashfold MNR, Yang X, Yuan K. Vacuum ultraviolet photodissociation of sulfur dioxide and its implications for oxygen production in the early Earth's atmosphere. Chem Sci 2023; 14:8255-8261. [PMID: 37564413 PMCID: PMC10411858 DOI: 10.1039/d3sc03328g] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 07/25/2023] [Indexed: 08/12/2023] Open
Abstract
The emergence of molecular oxygen (O2) in the Earth's primitive atmosphere is an issue of major interest. Although the biological processes leading to its accumulation in the Earth's atmosphere are well understood, its abiotic source is still not fully established. Here, we report a new direct dissociation channel yielding S(1D) + O2(a1Δg/X3Σg-) products from vacuum ultraviolet (VUV) photodissociation of SO2 in the wavelength range between 120 and 160 nm. Experimental results show O2 production to be an important channel from SO2 VUV photodissociation, with a branching ratio of 30 ± 5% at the H Lyman-α wavelength (121.6 nm). The relatively large amounts of SO2 emitted from volcanic eruptions in the Earth's late Archaean eon imply that VUV photodissociation of SO2 could have provided a crucial additional source term in the O2 budget in the Earth's primitive atmosphere. The results could also have implications for abiotic oxygen formation on other planets with atmospheres rich in volcanically outgassed SO2.
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Affiliation(s)
- Yao Chang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences 457 Zhongshan Road Dalian 116023 China
| | - Yanlin Fu
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences 457 Zhongshan Road Dalian 116023 China
| | - Zhichao Chen
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences 457 Zhongshan Road Dalian 116023 China
| | - Zijie Luo
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences 457 Zhongshan Road Dalian 116023 China
- Marine Engineering College, Dalian Maritime University Liaoning 116026 China
| | - Yarui Zhao
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences 457 Zhongshan Road Dalian 116023 China
| | - Zhenxing Li
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences 457 Zhongshan Road Dalian 116023 China
| | - Weiqing Zhang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences 457 Zhongshan Road Dalian 116023 China
| | - Guorong Wu
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences 457 Zhongshan Road Dalian 116023 China
| | - Bina Fu
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences 457 Zhongshan Road Dalian 116023 China
- University of Chinese Academy of Sciences Beijing 100049 P. R. China
- Hefei National Laboratory Hefei 230088 China
| | - Dong H Zhang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences 457 Zhongshan Road Dalian 116023 China
- Hefei National Laboratory Hefei 230088 China
- Department of Chemistry, Center for Advanced Light Source Research, College of Science, Southern University of Science and Technology Shenzhen 518055 China
| | | | - Xueming Yang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences 457 Zhongshan Road Dalian 116023 China
- Hefei National Laboratory Hefei 230088 China
- Department of Chemistry, Center for Advanced Light Source Research, College of Science, Southern University of Science and Technology Shenzhen 518055 China
| | - Kaijun Yuan
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences 457 Zhongshan Road Dalian 116023 China
- University of Chinese Academy of Sciences Beijing 100049 P. R. China
- Hefei National Laboratory Hefei 230088 China
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4
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Wallner M, Jarraya M, Olsson E, Ideböhn V, Squibb RJ, Ben Yaghlane S, Nyman G, Eland JH, Feifel R, Hochlaf M. Abiotic molecular oxygen production-Ionic pathway from sulfur dioxide. SCIENCE ADVANCES 2022; 8:eabq5411. [PMID: 35984889 PMCID: PMC9390983 DOI: 10.1126/sciadv.abq5411] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 07/06/2022] [Indexed: 06/15/2023]
Abstract
Molecular oxygen, O2, is vital to life on Earth and possibly also on exoplanets. Although the biogenic processes leading to its accumulation in Earth's atmosphere are well understood, its abiotic origin is still not fully established. Here, we report combined experimental and theoretical evidence for electronic state-selective production of O2 from SO2, a chemical constituent of many planetary atmospheres and one that played an important part on Earth in the Great Oxidation Event. The O2 production involves dissociative double ionization of SO2 leading to efficient formation of the [Formula: see text] ion, which can be converted to abiotic O2 by electron neutralization or by charge exchange. This formation process may contribute substantially to the abundance of O2 and related ions in planetary atmospheres, such as the Jovian moons Io, Europa, and Ganymede. We suggest that this sort of ionic pathway for the formation of abiotic O2 involving multiply charged molecular ion decomposition may also exist for other atmospheric and planetary molecules.
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Affiliation(s)
- Måns Wallner
- University of Gothenburg, Department of Physics, Origovägen 6B, 412 58 Gothenburg, Sweden
| | - Mahmoud Jarraya
- Université de Tunis El Manar, Faculté des Sciences de Tunis, Laboratoire de Spectroscopie Atomique, Moléculaire et Applications—LSAMA, 2092 Tunis, Tunisia
- Université Gustave Eiffel, COSYS/IMSE, 5 Bd Descartes, 77454 Champs sur Marne, France
| | - Emelie Olsson
- University of Gothenburg, Department of Physics, Origovägen 6B, 412 58 Gothenburg, Sweden
| | - Veronica Ideböhn
- University of Gothenburg, Department of Physics, Origovägen 6B, 412 58 Gothenburg, Sweden
| | - Richard J. Squibb
- University of Gothenburg, Department of Physics, Origovägen 6B, 412 58 Gothenburg, Sweden
| | - Saida Ben Yaghlane
- Université de Tunis El Manar, Faculté des Sciences de Tunis, Laboratoire de Spectroscopie Atomique, Moléculaire et Applications—LSAMA, 2092 Tunis, Tunisia
| | - Gunnar Nyman
- University of Gothenburg, Department of Chemistry and Molecular Biology, Kemigården 4, 412 96 Gothenburg, Sweden
| | - John H.D. Eland
- Oxford University, Department of Chemistry, Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford OX1 3QZ, UK
| | - Raimund Feifel
- University of Gothenburg, Department of Physics, Origovägen 6B, 412 58 Gothenburg, Sweden
| | - Majdi Hochlaf
- Université Gustave Eiffel, COSYS/IMSE, 5 Bd Descartes, 77454 Champs sur Marne, France
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5
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Abstract
The large-scale dynamics of ocean oxygenation have changed dramatically throughout Earth's history, in step with major changes in the abundance of O2 in the atmosphere and changes to marine nutrient availability. A comprehensive mechanistic understanding of this history requires insights from oceanography, marine geology, geochemistry, geomicrobiology, evolutionary ecology, and Earth system modeling. Here, we attempt to synthesize the major features of evolving ocean oxygenation on Earth through more than 3 billion years of planetary history. We review the fundamental first-order controls on ocean oxygen distribution and summarize the current understanding of the history of ocean oxygenation on Earth from empirical and theoretical perspectives-integrating geochemical reconstructions of oceanic and atmospheric chemistry, genomic constraints on evolving microbial metabolism, and mechanistic biogeochemical models. These changes are used to illustrate primary regimes of large-scale ocean oxygenation and to highlight feedbacks that can act to stabilize and destabilize the ocean-atmosphere system in anoxic, low-oxygen, and high-oxygen states.
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Affiliation(s)
- Christopher T Reinhard
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, USA;
- Alternative Earths Team, Interdisciplinary Consortia for Astrobiology Research, National Aeronautics and Space Administration, Riverside, California 92521, USA
- Nexus for Exoplanet System Science (NExSS), National Aeronautics and Space Administration, Washington, DC 20546, USA
| | - Noah J Planavsky
- Alternative Earths Team, Interdisciplinary Consortia for Astrobiology Research, National Aeronautics and Space Administration, Riverside, California 92521, USA
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut 06511, USA
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6
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He H, Wu X, Xian H, Zhu J, Yang Y, Lv Y, Li Y, Konhauser KO. An abiotic source of Archean hydrogen peroxide and oxygen that pre-dates oxygenic photosynthesis. Nat Commun 2021; 12:6611. [PMID: 34785682 PMCID: PMC8595356 DOI: 10.1038/s41467-021-26916-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 10/21/2021] [Indexed: 11/29/2022] Open
Abstract
The evolution of oxygenic photosynthesis is a pivotal event in Earth's history because the O2 released fundamentally changed the planet's redox state and facilitated the emergence of multicellular life. An intriguing hypothesis proposes that hydrogen peroxide (H2O2) once acted as the electron donor prior to the evolution of oxygenic photosynthesis, but its abundance during the Archean would have been limited. Here, we report a previously unrecognized abiotic pathway for Archean H2O2 production that involves the abrasion of quartz surfaces and the subsequent generation of surface-bound radicals that can efficiently oxidize H2O to H2O2 and O2. We propose that in turbulent subaqueous environments, such as rivers, estuaries and deltas, this process could have provided a sufficient H2O2 source that led to the generation of biogenic O2, creating an evolutionary impetus for the origin of oxygenic photosynthesis.
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Affiliation(s)
- Hongping He
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640, Guangzhou, China.
- CAS Center for Excellence in Deep Earth Science, 510640, Guangzhou, China.
- University of Chinese Academy of Sciences, 100049, Beijing, China.
| | - Xiao Wu
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640, Guangzhou, China
- CAS Center for Excellence in Deep Earth Science, 510640, Guangzhou, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Haiyang Xian
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640, Guangzhou, China
- CAS Center for Excellence in Deep Earth Science, 510640, Guangzhou, China
| | - Jianxi Zhu
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640, Guangzhou, China
- CAS Center for Excellence in Deep Earth Science, 510640, Guangzhou, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Yiping Yang
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640, Guangzhou, China
- CAS Center for Excellence in Deep Earth Science, 510640, Guangzhou, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Ying Lv
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640, Guangzhou, China
- CAS Center for Excellence in Deep Earth Science, 510640, Guangzhou, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Yiliang Li
- Department of Earth Sciences, The University of Hong Kong, 999077, Hong Kong, China.
| | - Kurt O Konhauser
- Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, T6G 2E3, Canada.
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7
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Three body photodissociation of the water molecule and its implications for prebiotic oxygen production. Nat Commun 2021; 12:2476. [PMID: 33931653 PMCID: PMC8087761 DOI: 10.1038/s41467-021-22824-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 04/01/2021] [Indexed: 11/20/2022] Open
Abstract
The provenance of oxygen on the Earth and other planets in the Solar System is a fundamental issue. It has been widely accepted that the only prebiotic pathway to produce oxygen in the Earth’s primitive atmosphere was via vacuum ultraviolet (VUV) photodissociation of CO2 and subsequent two O atom recombination. Here, we provide experimental evidence of three-body dissociation (TBD) of H2O to produce O atoms in both 1D and 3P states upon VUV excitation using a tunable VUV free electron laser. Experimental results show that the TBD is the dominant pathway in the VUV H2O photochemistry at wavelengths between 90 and 107.4 nm. The relative abundance of water in the interstellar space with its exposure to the intense VUV radiation suggests that the TBD of H2O and subsequent O atom recombination should be an important prebiotic O2-production, which may need to be incorporated into interstellar photochemical models. Three-body dissociation of water, producing one oxygen and two hydrogen atoms, has been difficult to investigate due to the lack of intense vacuum ultraviolet sources. Here, using a tunable free-electron laser, the authors obtain quantum yields for this channel showing that it is a possible route to prebiotic oxygen formation in interstellar environments.
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8
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Li Q, Liu F, Lin F, Lin W, Wang X. An Organic Molecular Photocatalyst Releasing Oxygen from Water. CHEMSUSCHEM 2019; 12:4854-4858. [PMID: 31419059 DOI: 10.1002/cssc.201901899] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 08/11/2019] [Indexed: 06/10/2023]
Abstract
Artificial photosynthesis employing solar energy is one of the best means of reaching a sustainable energy cycle, in which water is oxidized to oxygen and supplies electrons for fuel generation. The development of suitable oxygen evolution materials driven by sunlight is hence the most challenging research topic in the field of photocatalysis. Herein, photocatalytic O2 production from water at a rate of 22.6 μmol h-1 was performed by using a pyrene-based organic molecule constructed through the Ullmann coupling reaction. Its significantly improved light-harvesting ability and notably accelerated separation and transfer of photogenerated charges enhanced the O2 evolution efficiency. This study highlights the structural design of organic molecules applied to photocatalytic water splitting.
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Affiliation(s)
- Qinghe Li
- State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou, 350002, P.R. China
| | - Feng Liu
- State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou, 350002, P.R. China
| | - Feng Lin
- State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou, 350002, P.R. China
| | - Wei Lin
- State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou, 350002, P.R. China
| | - Xinchen Wang
- State Key Laboratory of Photocatalysis on Energy and Environment, College of Chemistry, Fuzhou University, Fuzhou, 350002, P.R. China
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9
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10
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Direct dioxygen evolution in collisions of carbon dioxide with surfaces. Nat Commun 2019; 10:2294. [PMID: 31127109 PMCID: PMC6534623 DOI: 10.1038/s41467-019-10342-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Accepted: 04/29/2019] [Indexed: 11/18/2022] Open
Abstract
The intramolecular conversion of CO2 to molecular oxygen is an exotic reaction, rarely observed even with extreme optical or electronic excitation means. Here we show that this reaction occurs readily when CO2 ions scatter from solid surfaces in a two-step sequential collision process at hyperthermal incidence energies. The produced O2 is preferentially ionized by charge transfer from the surface over the predominant atomic oxygen product, leading to direct detection of both O2+ and O2−. First-principles simulations of the collisional dynamics reveal that O2 production proceeds via strongly-bent CO2 configurations, without visiting other intermediates. Bent CO2 provides dynamic access to the symmetric dissociation of CO2 to C+O2 with a calculated yield of 1 to 2% depending on molecular orientation. This unexpected collision-induced transformation of individual CO2 molecules provides an accessible pathway for generating O2 in astrophysical environments and may inspire plasma-driven electro- and photo-catalytic strategies for terrestrial CO2 reduction. Carbon dioxide can dissociate via different pathways depending on the amount of available energy. Here the authors investigate carbon dioxide collisions with metal substrates and observe a pathway producing molecular oxygen, which might explain the presence of oxygen in abiotic environments.
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12
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Evolved Climates and Observational Discriminants for the TRAPPIST-1 Planetary System. ACTA ACUST UNITED AC 2018. [DOI: 10.3847/1538-4357/aae36a] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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13
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14
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Arney G, Domagal-Goldman SD, Meadows VS. Organic Haze as a Biosignature in Anoxic Earth-like Atmospheres. ASTROBIOLOGY 2018; 18:311-329. [PMID: 29189040 PMCID: PMC5867516 DOI: 10.1089/ast.2017.1666] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 09/20/2017] [Indexed: 05/21/2023]
Abstract
Early Earth may have hosted a biologically mediated global organic haze during the Archean eon (3.8-2.5 billion years ago). This haze would have significantly impacted multiple aspects of our planet, including its potential for habitability and its spectral appearance. Here, we model worlds with Archean-like levels of carbon dioxide orbiting the ancient Sun and an M4V dwarf (GJ 876) and show that organic haze formation requires methane fluxes consistent with estimated Earth-like biological production rates. On planets with high fluxes of biogenic organic sulfur gases (CS2, OCS, CH3SH, and CH3SCH3), photochemistry involving these gases can drive haze formation at lower CH4/CO2 ratios than methane photochemistry alone. For a planet orbiting the Sun, at 30× the modern organic sulfur gas flux, haze forms at a CH4/CO2 ratio 20% lower than at 1× the modern organic sulfur flux. For a planet orbiting the M4V star, the impact of organic sulfur gases is more pronounced: at 1× the modern Earth organic sulfur flux, a substantial haze forms at CH4/CO2 ∼ 0.2, but at 30× the organic sulfur flux, the CH4/CO2 ratio needed to form haze decreases by a full order of magnitude. Detection of haze at an anomalously low CH4/CO2 ratio could suggest the influence of these biogenic sulfur gases and therefore imply biological activity on an exoplanet. When these organic sulfur gases are not readily detectable in the spectrum of an Earth-like exoplanet, the thick organic haze they can help produce creates a very strong absorption feature at UV-blue wavelengths detectable in reflected light at a spectral resolution as low as 10. In direct imaging, constraining CH4 and CO2 concentrations will require higher spectral resolution, and R > 170 is needed to accurately resolve the structure of the CO2 feature at 1.57 μm, likely the most accessible CO2 feature on an Archean-like exoplanet. Key Words: Organic haze-Organic sulfur gases-Biosignatures-Archean Earth. Astrobiology 18, 311-329.
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Affiliation(s)
- Giada Arney
- NASA Goddard Space Flight Center, Greenbelt, Maryland
- NASA Astrobiology Institute Virtual Planetary Laboratory, University of Washington, Seattle, Washington
| | - Shawn D. Domagal-Goldman
- NASA Goddard Space Flight Center, Greenbelt, Maryland
- NASA Astrobiology Institute Virtual Planetary Laboratory, University of Washington, Seattle, Washington
| | - Victoria S. Meadows
- NASA Astrobiology Institute Virtual Planetary Laboratory, University of Washington, Seattle, Washington
- Astronomy Department, University of Washington, Seattle, Washington
- University of Washington Astrobiology Program, Seattle, Washington
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15
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Meadows VS, Arney GN, Schwieterman EW, Lustig-Yaeger J, Lincowski AP, Robinson T, Domagal-Goldman SD, Deitrick R, Barnes RK, Fleming DP, Luger R, Driscoll PE, Quinn TR, Crisp D. The Habitability of Proxima Centauri b: Environmental States and Observational Discriminants. ASTROBIOLOGY 2018; 18:133-189. [PMID: 29431479 PMCID: PMC5820795 DOI: 10.1089/ast.2016.1589] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 09/04/2017] [Indexed: 05/21/2023]
Abstract
Proxima Centauri b provides an unprecedented opportunity to understand the evolution and nature of terrestrial planets orbiting M dwarfs. Although Proxima Cen b orbits within its star's habitable zone, multiple plausible evolutionary paths could have generated different environments that may or may not be habitable. Here, we use 1-D coupled climate-photochemical models to generate self-consistent atmospheres for several evolutionary scenarios, including high-O2, high-CO2, and more Earth-like atmospheres, with both oxic and anoxic compositions. We show that these modeled environments can be habitable or uninhabitable at Proxima Cen b's position in the habitable zone. We use radiative transfer models to generate synthetic spectra and thermal phase curves for these simulated environments, and use instrument models to explore our ability to discriminate between possible planetary states. These results are applicable not only to Proxima Cen b but to other terrestrial planets orbiting M dwarfs. Thermal phase curves may provide the first constraint on the existence of an atmosphere. We find that James Webb Space Telescope (JWST) observations longward of 10 μm could characterize atmospheric heat transport and molecular composition. Detection of ocean glint is unlikely with JWST but may be within the reach of larger-aperture telescopes. Direct imaging spectra may detect O4 absorption, which is diagnostic of massive water loss and O2 retention, rather than a photosynthetic biosphere. Similarly, strong CO2 and CO bands at wavelengths shortward of 2.5 μm would indicate a CO2-dominated atmosphere. If the planet is habitable and volatile-rich, direct imaging will be the best means of detecting habitability. Earth-like planets with microbial biospheres may be identified by the presence of CH4-which has a longer atmospheric lifetime under Proxima Centauri's incident UV-and either photosynthetically produced O2 or a hydrocarbon haze layer. Key Words: Planetary habitability and biosignatures-Planetary atmospheres-Exoplanets-Spectroscopic biosignatures-Planetary science-Proxima Centauri b. Astrobiology 18, 133-189.
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Affiliation(s)
- Victoria S. Meadows
- Astronomy Department, University of Washington, Seattle, Washington
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
| | - Giada N. Arney
- Astronomy Department, University of Washington, Seattle, Washington
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
- Planetary Systems Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland
| | - Edward W. Schwieterman
- Astronomy Department, University of Washington, Seattle, Washington
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
- NASA Postdoctoral Program, Universities Space Research Association, Columbia, Maryland
- Department of Earth Sciences, University of California at Riverside, Riverside, California
| | - Jacob Lustig-Yaeger
- Astronomy Department, University of Washington, Seattle, Washington
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
| | - Andrew P. Lincowski
- Astronomy Department, University of Washington, Seattle, Washington
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
| | - Tyler Robinson
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
- Department of Astronomy and Astrophysics, University of California, Santa Cruz, California
| | - Shawn D. Domagal-Goldman
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
- Planetary Environments Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland
| | - Russell Deitrick
- Astronomy Department, University of Washington, Seattle, Washington
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
| | - Rory K. Barnes
- Astronomy Department, University of Washington, Seattle, Washington
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
| | - David P. Fleming
- Astronomy Department, University of Washington, Seattle, Washington
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
| | - Rodrigo Luger
- Astronomy Department, University of Washington, Seattle, Washington
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
| | - Peter E. Driscoll
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
- Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington, DC
| | - Thomas R. Quinn
- Astronomy Department, University of Washington, Seattle, Washington
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
| | - David Crisp
- NASA Astrobiology Institute—Virtual Planetary Laboratory Lead Team, USA
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
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16
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Yao Y, Giapis KP. Dynamic molecular oxygen production in cometary comae. Nat Commun 2017; 8:15298. [PMID: 28480881 PMCID: PMC5424151 DOI: 10.1038/ncomms15298] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 03/07/2017] [Indexed: 11/09/2022] Open
Abstract
Abundant molecular oxygen was discovered in the coma of comet 67P/Churyumov-Gerasimenko. Its origin was ascribed to primordial gaseous O2 incorporated into the nucleus during the comet's formation. This thesis was put forward after discounting several O2 production mechanisms in comets, including photolysis and radiolysis of water, solar wind-surface interactions and gas-phase collisions. Here we report an original Eley-Rideal reaction mechanism, which permits direct O2 formation in single collisions of energetic water ions with oxidized cometary surface analogues. The reaction proceeds by H2O+ abstracting a surface O-atom, then forming an excited precursor state, which dissociates to produce O2-. Subsequent photo-detachment leads to molecular O2, whose presence in the coma may thus be linked directly to water molecules and their interaction with the solar wind. This abiotic O2 production mechanism is consistent with reported trends in the 67P coma and raises awareness of the role of energetic negative ions in comets.
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Affiliation(s)
- Yunxi Yao
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Konstantinos P Giapis
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
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17
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Pale Orange Dots: The Impact of Organic Haze on the Habitability and Detectability of Earthlike Exoplanets. ACTA ACUST UNITED AC 2017. [DOI: 10.3847/1538-4357/836/1/49] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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18
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Babechuk MG, Kleinhanns IC, Schoenberg R. Chromium geochemistry of the ca. 1.85 Ga Flin Flon paleosol. GEOBIOLOGY 2017; 15:30-50. [PMID: 27444369 DOI: 10.1111/gbi.12203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 06/20/2016] [Indexed: 06/06/2023]
Abstract
Fractionation of stable Cr isotopes has been measured in Archaean paleosols and marine sedimentary rocks and interpreted to record the terrestrial oxidation of Cr(III) to Cr(VI), providing possible indirect evidence for the emergence of oxygenic photosynthesis. However, these fractionations occur amidst evidence from other geochemical proxies for a pervasively anoxic atmosphere. This study examined the Cr geochemistry of the ca. 1.85 Ga Flin Flon paleosol, which developed under an atmosphere unambiguously oxidising enough to quantitatively convert Fe(II) to Fe(III) during pedogenesis. The paleosol shows an extreme range in Cr isotope composition of 2.76 ‰ δ53/52 Cr. The protolith greenstone (δ53/52 Cr: -0.23 ‰), the deepest weathering horizon (δ53/52 Cr: -0.15 to -0.23 ‰) and a residual corestone in the upper paleosol (δ53/52 Cr: -0.01 ‰) all exhibit Cr isotopic compositions comparable to unaltered igneous rocks. The most significant isotopic fractionation is preserved in the areas influenced by oxidative subaerial weathering (i.e. increase in Fe(III)/Fe(II)) and the greatest loss of mobile elements. The uppermost paleosol horizon is both Cr and Mn depleted and offset to significantly 53 Cr-enriched compositions (δ53/52 Cr values between +1.50 and +2.38 ‰), which is not easily modelled with the oxidation of Cr(III) and loss of isotopically heavy Cr(VI). Instead, the currently preferred model for these data invokes the open-system removal of isotopically light aqueous Cr(III) during either pedogenesis or subsequent hydrothermal/metamorphic alteration. The 53 Cr enrichment would then represent the preferential dissolution or complexation of isotopically light aqueous Cr(III) species (enhanced by lower pH conditions and possibly the presence of complexing ligands) and/or the residual signature from preferential adsorption of isotopically heavy Cr(III). Both scenarios would contradict the widely held assumption that only redox reactions of Cr can generate large magnitude isotopic fractionations and, if substantiated, non-redox isotope effects would complicate the conclusive fingerprinting of ancient atmospheric O2 from Cr isotope data alone.
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Affiliation(s)
- M G Babechuk
- Department of Geosciences, University of Tübingen, Tübingen, Germany
- Department of Geology, Trinity College Dublin, Dublin 2, Ireland
| | - I C Kleinhanns
- Department of Geosciences, University of Tübingen, Tübingen, Germany
| | - R Schoenberg
- Department of Geosciences, University of Tübingen, Tübingen, Germany
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Arney G, Domagal-Goldman SD, Meadows VS, Wolf ET, Schwieterman E, Charnay B, Claire M, Hébrard E, Trainer MG. The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth. ASTROBIOLOGY 2016; 16:873-899. [PMID: 27792417 PMCID: PMC5148108 DOI: 10.1089/ast.2015.1422] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 07/13/2016] [Indexed: 05/21/2023]
Abstract
Recognizing whether a planet can support life is a primary goal of future exoplanet spectral characterization missions, but past research on habitability assessment has largely ignored the vastly different conditions that have existed in our planet's long habitable history. This study presents simulations of a habitable yet dramatically different phase of Earth's history, when the atmosphere contained a Titan-like, organic-rich haze. Prior work has claimed a haze-rich Archean Earth (3.8-2.5 billion years ago) would be frozen due to the haze's cooling effects. However, no previous studies have self-consistently taken into account climate, photochemistry, and fractal hazes. Here, we demonstrate using coupled climate-photochemical-microphysical simulations that hazes can cool the planet's surface by about 20 K, but habitable conditions with liquid surface water could be maintained with a relatively thick haze layer (τ ∼ 5 at 200 nm) even with the fainter young Sun. We find that optically thicker hazes are self-limiting due to their self-shielding properties, preventing catastrophic cooling of the planet. Hazes may even enhance planetary habitability through UV shielding, reducing surface UV flux by about 97% compared to a haze-free planet and potentially allowing survival of land-based organisms 2.7-2.6 billion years ago. The broad UV absorption signature produced by this haze may be visible across interstellar distances, allowing characterization of similar hazy exoplanets. The haze in Archean Earth's atmosphere was strongly dependent on biologically produced methane, and we propose that hydrocarbon haze may be a novel type of spectral biosignature on planets with substantial levels of CO2. Hazy Archean Earth is the most alien world for which we have geochemical constraints on environmental conditions, providing a useful analogue for similar habitable, anoxic exoplanets. Key Words: Haze-Archean Earth-Exoplanets-Spectra-Biosignatures-Planetary habitability. Astrobiology 16, 873-899.
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Affiliation(s)
- Giada Arney
- Astronomy Department, University of Washington, Seattle, Washington, USA
- NASA Astrobiology Institute Virtual Planetary Laboratory, University of Washington, Seattle, Washington, USA
- Astrobiology Program, University of Washington, Seattle, Washington, USA
- Now at: NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
- Now at: NASA Postdoctoral Program, Universities Space Research Association, Columbia, Maryland, USA
| | - Shawn D. Domagal-Goldman
- NASA Astrobiology Institute Virtual Planetary Laboratory, University of Washington, Seattle, Washington, USA
- NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Victoria S. Meadows
- Astronomy Department, University of Washington, Seattle, Washington, USA
- NASA Astrobiology Institute Virtual Planetary Laboratory, University of Washington, Seattle, Washington, USA
- Astrobiology Program, University of Washington, Seattle, Washington, USA
| | - Eric T. Wolf
- Department of Atmospheric and Oceanic Sciences, Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, Boulder, Colorado, USA
| | - Edward Schwieterman
- Astronomy Department, University of Washington, Seattle, Washington, USA
- NASA Astrobiology Institute Virtual Planetary Laboratory, University of Washington, Seattle, Washington, USA
- Astrobiology Program, University of Washington, Seattle, Washington, USA
- Now at: NASA Postdoctoral Program, Universities Space Research Association, Columbia, Maryland, USA
- Now at: University of California at Riverside, Riverside, California, USA
- Blue Marble Institute of Science, Seattle, Washington, USA
| | - Benjamin Charnay
- Astronomy Department, University of Washington, Seattle, Washington, USA
- NASA Astrobiology Institute Virtual Planetary Laboratory, University of Washington, Seattle, Washington, USA
- Astrobiology Program, University of Washington, Seattle, Washington, USA
- Now at: Paris-Meudon Observatory, Paris, France
| | - Mark Claire
- NASA Astrobiology Institute Virtual Planetary Laboratory, University of Washington, Seattle, Washington, USA
- Blue Marble Institute of Science, Seattle, Washington, USA
- Department of Earth and Environmental Sciences, University of St Andrews, St Andrews, UK
| | - Eric Hébrard
- NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
- University of Exeter, Exeter, Devon, UK
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20
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Dissociative electron attachment to CO2 produces molecular oxygen. Nat Chem 2016; 8:258-63. [DOI: 10.1038/nchem.2427] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Accepted: 11/20/2015] [Indexed: 12/22/2022]
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21
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Harman CE, Schwieterman EW, Schottelkotte JC, Kasting JF. ABIOTIC O2LEVELS ON PLANETS AROUND F, G, K, AND M STARS: POSSIBLE FALSE POSITIVES FOR LIFE? ACTA ACUST UNITED AC 2015. [DOI: 10.1088/0004-637x/812/2/137] [Citation(s) in RCA: 150] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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22
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Lu Z, Chang YC, Yin QZ, Ng CY, Jackson WM. Photochemistry. Evidence for direct molecular oxygen production in CO₂ photodissociation. Science 2014; 346:61-4. [PMID: 25278605 DOI: 10.1126/science.1257156] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Photodissociation of carbon dioxide (CO2) has long been assumed to proceed exclusively to carbon monoxide (CO) and oxygen atom (O) primary products. However, recent theoretical calculations suggested that an exit channel to produce C + O2 should also be energetically accessible. Here we report the direct experimental evidence for the C + O2 channel in CO2 photodissociation near the energetic threshold of the C((3)P) + O2(X(3)Σ(g)(-)) channel with a yield of 5 ± 2% using vacuum ultraviolet laser pump-probe spectroscopy and velocity-map imaging detection of the C((3)PJ) product between 101.5 and 107.2 nanometers. Our results may have implications for nonbiological oxygen production in CO2-heavy atmospheres.
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Affiliation(s)
- Zhou Lu
- Department of Chemistry, University of California, Davis, CA 95616, USA
| | - Yih Chung Chang
- Department of Chemistry, University of California, Davis, CA 95616, USA
| | - Qing-Zhu Yin
- Department of Earth and Planetary Sciences, University of California, Davis, CA 95616, USA
| | - C Y Ng
- Department of Chemistry, University of California, Davis, CA 95616, USA.
| | - William M Jackson
- Department of Chemistry, University of California, Davis, CA 95616, USA.
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23
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Harman CE, Kasting JF, Wolf ET. Atmospheric production of glycolaldehyde under hazy prebiotic conditions. ORIGINS LIFE EVOL B 2013; 43:77-98. [PMID: 23695543 DOI: 10.1007/s11084-013-9332-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 04/11/2013] [Indexed: 10/26/2022]
Abstract
The early Earth's atmosphere, with extremely low levels of molecular oxygen and an appreciable abiotic flux of methane, could have been a source of organic compounds necessary for prebiotic chemistry. Here, we investigate the formation of a key RNA precursor, glycolaldehyde (2-hydroxyacetaldehyde, or GA) using a 1-dimensional photochemical model. Maximum atmospheric production of GA occurs when the CH4:CO2 ratio is close to 0.02. The total atmospheric production rate of GA remains small, only 1 × 10(7) mol yr(-1). Somewhat greater amounts of GA production, up to 2 × 10(8) mol yr(-1), could have been provided by the formose reaction or by direct delivery from space. Even with these additional production mechanisms, open ocean GA concentrations would have remained at or below ~1 μM, much smaller than the 1-2 M concentrations required for prebiotic synthesis routes like those proposed by Powner et al. (Nature 459:239-242, 2009). Additional production or concentration mechanisms for GA, or alternative formation mechanisms for RNA, are needed, if this was indeed how life originated on the early Earth.
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Affiliation(s)
- Chester E Harman
- Department of Geosciences, Penn State University, University Park, PA 16802, USA.
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24
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Photochemical Consequences of Enhanced CO2
Levels in Earth's Early Atmosphere. ACTA ACUST UNITED AC 2013. [DOI: 10.1029/gm032p0612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
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25
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Domagal-Goldman SD, Meadows VS, Claire MW, Kasting JF. Using biogenic sulfur gases as remotely detectable biosignatures on anoxic planets. ASTROBIOLOGY 2011; 11:419-41. [PMID: 21663401 PMCID: PMC3133782 DOI: 10.1089/ast.2010.0509] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We used one-dimensional photochemical and radiative transfer models to study the potential of organic sulfur compounds (CS(2), OCS, CH(3)SH, CH(3)SCH(3), and CH(3)S(2)CH(3)) to act as remotely detectable biosignatures in anoxic exoplanetary atmospheres. Concentrations of organic sulfur gases were predicted for various biogenic sulfur fluxes into anoxic atmospheres and were found to increase with decreasing UV fluxes. Dimethyl sulfide (CH(3)SCH(3), or DMS) and dimethyl disulfide (CH(3)S(2)CH(3), or DMDS) concentrations could increase to remotely detectable levels, but only in cases of extremely low UV fluxes, which may occur in the habitable zone of an inactive M dwarf. The most detectable feature of organic sulfur gases is an indirect one that results from an increase in ethane (C(2)H(6)) over that which would be predicted based on the planet's methane (CH(4)) concentration. Thus, a characterization mission could detect these organic sulfur gases-and therefore the life that produces them-if it could sufficiently quantify the ethane and methane in the exoplanet's atmosphere.
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26
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Haqq-Misra J, Kasting JF, Lee S. Availability of O(2) and H(2)O(2) on pre-photosynthetic Earth. ASTROBIOLOGY 2011; 11:293-302. [PMID: 21545266 PMCID: PMC3097080 DOI: 10.1089/ast.2010.0572] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Old arguments that free O(2) must have been available at Earth's surface prior to the origin of photosynthesis have been revived by a new study that shows that aerobic respiration can occur at dissolved oxygen concentrations much lower than had previously been thought, perhaps as low as 0.05 nM, which corresponds to a partial pressure for O(2) of about 4 × 10(-8) bar. We used numerical models to study whether such O(2) concentrations might have been provided by atmospheric photochemistry. Results show that disproportionation of H(2)O(2) near the surface might have yielded enough O(2) to satisfy this constraint. Alternatively, poleward transport of O(2) from the equatorial stratosphere into the polar night region, followed by downward transport in the polar vortex, may have brought O(2) directly to the surface. Thus, our calculations indicate that this "early respiration" hypothesis might be physically reasonable.
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Affiliation(s)
- Jacob Haqq-Misra
- Department of Meteorology, The Pennsylvania State University, University Park, PA 16802, USA.
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27
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Zhang XH, Weissbach H. Origin and evolution of the protein-repairing enzymes methionine sulphoxide reductases. Biol Rev Camb Philos Soc 2008; 83:249-57. [PMID: 18557976 DOI: 10.1111/j.1469-185x.2008.00042.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The majority of extant life forms thrive in an O2-rich environment, which unavoidably induces the production of reactive oxygen species (ROS) during cellular activities. ROS readily oxidize methionine (Met) residues in proteins/peptides to form methionine sulphoxide [Met(O)] that can lead to impaired protein function. Two methionine sulphoxide reductases, MsrA and MsrB, catalyse the reduction of the S and R epimers, respectively, of Met(O) in proteins to Met. The Msr system has two known functions in protecting cells against oxidative damage. The first is to repair proteins that have lost activity due to Met oxidation and the second is to function as part of a scavenger system to remove ROS through the reversible oxidation/reduction of Met residues in proteins. Bacterial, plant and animal cells lacking MsrA are known to be more sensitive to oxidative stress. The Msr system is considered an important cellular defence mechanism to protect against oxidative stress and may be involved in ageing/senescence. MsrA is present in all known eukaryotes and eubacteria and a majority of archaea, reflecting its essential role in cellular life. MsrB is found in all eukaryotes and the majority of eubacteria and archaea but is absent in some eubacteria and archaea, which may imply a less important role of MsrB compared to MsrA. MsrA and MsrB share no sequence or structure homology, and therefore probably emerged as a result of independent evolutionary events. The fact that some archaea lack msr genes raises the question of how these archaea cope with oxidative damage to proteins and consequently of the significance of msr evolution in oxic eukaryotes dealing with oxidative stress. Our best hypothesis is that the presence of ROS-destroying enzymes such as peroxiredoxins and a lower dissolved O2 concentration in those msr-lacking organisms grown at high temperatures might account for the successful survival of these organisms under oxidative stress.
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Affiliation(s)
- Xing-Hai Zhang
- Department of Biological Sciences, Florida Atlantic University, Boca Raton 33431, USA.
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28
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Goldblatt C, Lenton TM, Watson AJ. Bistability of atmospheric oxygen and the Great Oxidation. Nature 2006; 443:683-6. [PMID: 17036001 DOI: 10.1038/nature05169] [Citation(s) in RCA: 204] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2006] [Accepted: 08/14/2006] [Indexed: 11/09/2022]
Abstract
The history of the Earth has been characterized by a series of major transitions separated by long periods of relative stability. The largest chemical transition was the 'Great Oxidation', approximately 2.4 billion years ago, when atmospheric oxygen concentrations rose from less than 10(-5) of the present atmospheric level (PAL) to more than 0.01 PAL, and possibly to more than 0.1 PAL. This transition took place long after oxygenic photosynthesis is thought to have evolved, but the causes of this delay and of the Great Oxidation itself remain uncertain. Here we show that the origin of oxygenic photosynthesis gave rise to two simultaneously stable steady states for atmospheric oxygen. The existence of a low-oxygen (less than 10(-5) PAL) steady state explains how a reducing atmosphere persisted for at least 300 million years after the onset of oxygenic photosynthesis. The Great Oxidation can be understood as a switch to the high-oxygen (more than 5 x 10(-3) PAL) steady state. The bistability arises because ultraviolet shielding of the troposphere by ozone becomes effective once oxygen levels exceed 10(-5) PAL, causing a nonlinear increase in the lifetime of atmospheric oxygen. Our results indicate that the existence of oxygenic photosynthesis is not a sufficient condition for either an oxygen-rich atmosphere or the presence of an ozone layer, which has implications for detecting life on other planets using atmospheric analysis and for the evolution of multicellular life.
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Affiliation(s)
- Colin Goldblatt
- School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, UK.
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29
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Abstract
The early history of life on earth may have been characterized by coevolution of microbial metabolism and atmospheric composition. Metabolic developments affected the composition of the atmosphere, and the resulting changes in the atmosphere stimulated the evolution of new metabolic capabilities. The first organisms eked out an existence by deriving energy from the fermentation of organic compounds abiotically synthesized. The abiotic source was meager, however, and when autotrophy arose, life was freed from its dependence on abiotic synthesis. The expanded level of biological activity made possible by autotrophy resulted in an increased rate of burial of reduced organic matter in sea floor sediments. The resultant drain on the concentration of electron donors in the biosphere caused a decline in the hydrogen content of the atmosphere. Biological productivity was limited by the supply of reduced compounds. This paper explores the biogeochemical circulation of electron donors in the primitive anaerobic ocean, concluding that their shortage was so critical as to provide strong selective pressure for the evolution of algal photosynthesis.
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Affiliation(s)
- J C Walker
- Arecibo Observatory, National Astronomy and Ionosphere Center, Arecibo, Puerto Rico 00612, USA
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30
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Abstract
One-dimensional radiative convective and photochemical models are used to estimate the vertical temperature structure and composition of the earth's prebiotic atmosphere. Greatly enhanced CO2 levels (100-1000 times present) are required to keep the mean surface temperature above freezing in the face of decreased solar luminosity during the earth's early history. Such high CO2 partial pressures would have affected the atmospheric oxidation state by facilitating the photochemical production of soluble species including H2O2 and H2CO. Oxidation of ferrous iron in the oceans by H2O2 dissolved in rainwater should have kept the atmospheric H2 mixing ratio above 2x10(-4) and the ground-level O2 mixing ratio below 10(-11), regardless of the magnitude of the rate of volcanic release of reduced gases.
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Affiliation(s)
- J F Kasting
- NASA Ames Research Center, Moffett Field, CA 94035, USA
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31
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Abstract
Based upon arguments concerning properties of the environment and the energetics of nitrogen transformation reactions, new hypotheses regarding their evolution are presented. These hypotheses are supported by new calculations and observations germane to understanding the evolution of the nitrogen cycle. From calculations of shock production by meteor impact, we suggest that impact produced fixed nitrogen could have resulted in the entire reservoir of Earth's N2 being converted into fixed nitrogen at the end of accretion. We have significantly improved upon previous calculations of the abiotic fixation rate on the early earth and find a rate of fixation by lightning of approximately 1-3 x 10(16) molecules NO/J, which is 2 to 3 times greater than previous estimates. This strengthens the suggestion, corroborated by the predominance of a single nitrogenase enzyme, that biological nitrogen fixation may have been a late evolutionary development, after the development of an aerobic atmosphere. In addition, we show for the first time that HNO, predicted to be the main product of atmospheric photochemical reactions involving NO on the primitive Earth by photochemical models, would eventually become NO2- and NO3- after reaching the Earth's surface. Based upon microbe-environment interactions on an ecological as well as a biochemical scale we suggest that denitrification arose prior to aerobic respiration and that nitrification arose after the advent of an aerobic atmosphere. We hypothesize the following evolutionary sequence for the biological transformation of nitrogen compounds: Ammonification --> Denitrification --> Nitrification --> Nitrogen fixation.
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Affiliation(s)
- R L Mancinelli
- Solar System Exploration Branch, NASA-Ames Research Center, Moffett Field, CA 94035, USA
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Rosenqvist J, Chassefière E. Inorganic chemistry of O2 in a dense primitive atmosphere. PLANETARY AND SPACE SCIENCE 1995; 43:3-10. [PMID: 11538435 DOI: 10.1016/0032-0633(94)00202-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A simple steady-state photochemical model is developed in order to determine typical molecular oxygen concentrations for a comprehensive range of primitive abiotic atmospheres. Carbon dioxide is assumed to be the dominant constituent in these atmospheres since CO2 photodissociation may potentially result in the enhancement of the O2 partial pressure. The respective effects of the H2O content, temperature, eddy diffusion coefficient and UV flux on the results are investigated. It is shown that for any pressure at the surface, the partial pressure of molecular oxygen does not exceed 10 mbar. The peculiar case of a runaway greenhouse which has possibly taken place on Venus is qualitatively envisaged. Although O2 is basically absent in the present Venus atmosphere, a transient presence in a primitive stage cannot be ruled out. Possible mechanisms for O2 removal in such an atmosphere are reviewed. At the present stage, we think that the detection of large O2 amounts would be at least a good clue for the presence of life on an extrasolar planet.
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Affiliation(s)
- J Rosenqvist
- DESPA, Observatoire de Paris-Meudon, Meudon, France
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Kasting JF. O2 concentrations in dense primitive atmospheres: commentary. PLANETARY AND SPACE SCIENCE 1995; 43:11-13. [PMID: 11538422 DOI: 10.1016/0032-0633(94)00203-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Now that astronomers are, I understand, on the verge of detecting extrasolar planets, the question of whether such planets might be inhabited is beginning to be discussed in serious scientific circles. Specifically, astronomers such as Rosenqvist and Chassefiére (see the preceding article) are interested in whether spectroscopic measurements of free O2 in a planet's atmosphere might be used as evidence for life. As such, they have attempted to place constraints on the amount of O2 that might be found in the atmosphere of a lifeless planet or, more specifically, on a planet where oxygenic photosynthesis has not yet been invented. This question can be addressed by photochemical modeling, if one is careful about how one goes about it. The calculations presented here suggest an upper limit of approximately 10 mbar on the O2 partial pressure in a dominantly CO2 atmosphere.
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Affiliation(s)
- J F Kasting
- Department of Geosciences, Penn State University, University Park 16802, USA
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34
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HPLC and electrochemical investigations of the salt-induced peptide formation from glycine, alanine, valine and aspartic acid under possible prebiotic conditions. Inorganica Chim Acta 1993. [DOI: 10.1016/s0020-1693(00)91449-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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35
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36
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Rodrigo R, García-Álvarez E, López-González MJ, López-Moreno JJ. A nonsteady one-dimensional theoretical model of Mars' neutral atmospheric composition between 30 and 200 km. ACTA ACUST UNITED AC 1990. [DOI: 10.1029/jb095ib09p14795] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Wen JS, Pinto JP, Yung YL. Photochemistry of CO and H2O: analysis of laboratory experiments and applications to the prebiotic Earth's atmosphere. JOURNAL OF GEOPHYSICAL RESEARCH 1989; 94:14957-70. [PMID: 11538864 DOI: 10.1029/jd094id12p14957] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The role photochemical reactions in the early Earth's atmosphere played in the prebiotic synthesis of simple organic molecules was examined. We have extended an earlier calculation of formaldehyde production rates to more reduced carbon species, such as methanol, methane, and acetaldehyde. We have simulated the experimental results of Bar-Nun and Chang (1983) as an acid in the construction of our photochemical scheme and as a way of validating our model. Our results indicate that some fraction of CO2 and H2 present in the primitive atmosphere could have been converted to simple organic molecules. The exact amount is dependent on the partial pressure of CO2 and H2 in the atmosphere and on what assumptions are made concerning the shape of the absorption spectra of CO2 and H2O. In particular, the results are most sensitive to the presence or absence of absorption at wavelengths longward of 2000 angstroms. We also find that small quantities of CH4 could have been present in the prebiotic Earth's atmosphere as the result of the photoreduction of CO.
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Affiliation(s)
- J S Wen
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, USA
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Kasting JF. Theoretical constraints on oxygen and carbon dioxide concentrations in the Precambrian atmosphere. PRECAMBRIAN RESEARCH 1987; 34:205-29. [PMID: 11542097 DOI: 10.1016/0301-9268(87)90001-5] [Citation(s) in RCA: 127] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Simple (one-dimensional) climate models suggest that carbon dioxide concentrations during the Archean must have been at least 100-1000 times the present level to keep the Earth's surface temperature above freezing in the face of decreased solar luminosity. Such models provide only lower bounds on CO2, so it is possible that CO2 levels were substantially higher than this and that the Archean climate was much warmer than today. Periods of extensive glaciation during the early and late Proterozoic, on the other hand, indicate that the climate at these times was relatively cool. To be consistent with climate models CO2 partial pressures must have declined from approximately 0.03 to 0.3 bar around 2.5 Ga ago to between 10(-3) and 10(-2) bar at 0.8 Ga ago. This steep decrease in carbon dioxide concentrations may be inconsistent with paleosol data, which implies that pCO2 did not change appreciably during that time. Oxygen was essentially absent from the Earth's atmosphere and oceans prior to the emergence of a photosynthetic source, probably during the late Archean. During the early Proterozoic the atmosphere and surface ocean were apparently oxidizing, while the deep ocean remained reducing. An upper limit of 6 x 10(-3) bar for pO2 at this time can be derived by balancing the burial rate of organic carbon with the rate of oxidation of ferrous iron in the deep ocean. The establishment of oxidizing conditions in the deep ocean, marked by the disappearance of banded iron formations approximately 1.7 Ga ago, permitted atmospheric oxygen to climb to its present level. O2 concentrations may have remained substantially lower than today, however, until well into the Phanerozoic.
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Affiliation(s)
- J F Kasting
- NASA Ames Research Center, Moffett Field, CA 94035, USA
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Zahnle KJ. Photochemistry of methane and the formation of hydrocyanic acid (HCN) in the Earth's early atmosphere. ACTA ACUST UNITED AC 1986. [DOI: 10.1029/jd091id02p02819] [Citation(s) in RCA: 193] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Abstract
Tentative geochemical cycles for the pre-biologic Earth are developed by comparing the relative fluxes of oxygen, dissolved iron, and sulfide to the atmosphere and ocean. The flux of iron is found to exceed both the oxygen and the sulfide fluxes. Because of the insolubility of iron oxides and sulfides the implication is that dissolved iron was fairly abundant and that oxygen and sulfide were rare in the atmosphere and ocean. Sulfate, produced by the oxidation of volcanogenic sulfur gases, was the most abundant sulfur species in the ocean, but its concentration was low by modern standards because of the absence of the river-borne flux of dissolved sulfate produced by oxidative weathering of the continents. These findings are consistent with the geologic record of the isotopic composition of sedimentary sulfates and sulfides. Except in restricted environments, the sulfur metabolism of the earliest organisms probably involved oxidized sulfur species not sulfide.
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Affiliation(s)
- J C Walker
- Department of Atmospheric and Oceanic Science, The University of Michigan, Ann Arbor 48109, USA
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Kasting JF, Pollack JB. Effects of high CO2 levels on surface temperature and atmospheric oxidation state of the early Earth. JOURNAL OF ATMOSPHERIC CHEMISTRY 1984; 1:403-428. [PMID: 11541984 DOI: 10.1007/bf00053803] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
One-dimensional radiative-convective and photochemical models are used to examine the effects of enhanced CO2 concentrations on the surface temperature of the early Earth and the composition of the prebiotic atmosphere. Carbon dioxide concentrations of the order of 100-1000 times the present level are required to compensate for an expected solar luminosity decrease of 25-30%, if CO2 and H2O were the only greenhouse gases present. The primitive stratosphere was cold and dry, with a maximum H2O volume mixing ratio of 10(-6). The atmospheric oxidation state was controlled by the balance between volcanic emission of reduced gases, photo-stimulated oxidation of dissolved Fe+2 in the oceans, escape of hydrogen to space, and rainout of H2O2 and H2CO. At high CO2 levels, production of hydrogen owing to rainout of H2O2 would have kept the H2 mixing ratio above 2x10(-4) and the ground-level O2 mixing ratio below 10(-11), even if no other sources of hydrogen were present. Increased solar UV fluxes could have led to small changes in the ground-level mixing ratios of both O2 and H2.
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Affiliation(s)
- J F Kasting
- NASA Ames Research Center, Moffett Field, CA 94035, USA
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Ewers W. Chapter 13 Chemical Factors in the Deposition and Diagenesis of Banded Iron-Formation. IRON-FORMATION FACTS AND PROBLEMS 1983. [DOI: 10.1016/s0166-2635(08)70054-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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Levine JS, Augustsson TR, Natarajan M. The prebiological paleoatmosphere: stability and composition. ORIGINS OF LIFE 1982; 12:245-59. [PMID: 7162799 DOI: 10.1007/bf00926894] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
In the past, it was generally assumed that the early atmosphere of the Earth contained appreciable quantities of methane (CH4) and ammonia (NH3). This was the type of atmosphere believed to be the most suitable environment for chemical evolution, the nonbiological formation of complex organic molecules, the precursors of living systems. Photochemical considerations suggest that a CH4-NH3 dominated early atmosphere was probably very short-lived, if it ever existed at all. Instead, an early atmosphere of carbon dioxide (CO2) and nitrogen (N2) is favored by photochemical as well as geological and geochemical considerations. Photochemical calculations also indicate that the total oxygen column density of the prebiological paleoatmosphere did not exceed 10(-7) of the present atmospheric level.
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Abstract
The ideas of Harold Urey on the origin and evolution of the atmosphere have dominated thinking in this area for 3 decades. Recent progress in this area is reviewed, with particular emphasis on photochemical modeling studies of atmospheric evolution. Research into the paleoatmosphere can be divided into 3 distinct areas: (1) The photochemistry/chemistry of the prebiological paleoatmosphere, (2) the evolution of oxygen and the transition to an oxidizing atmosphere, and (3) the origin and evolution of ozone. Photochemical calculations indicate that the stability of a heavily reducing paleoatmosphere of CH4--NH3 was extremely shortlived, if such a prebiological atmosphere ever existed at all. A more mildly reducing early atmosphere of CO2--N2 is favored by photochemical considerations. Recent calculations of O2 in the prebiological paleoatmosphere vary from less than 10(-14) of present atmospheric level (PAL) to 10(-1) PAL. Clearly, additional work is indicated. The evolution of O3 as a function of O2 level has been investigated with increasingly detailed photochemical models that have included the photochemistry/chemistry of the oxygen, hydrogen, nitrogen, carbon, and chlorine species, as well as the effects of eddy transport, the rainout of water-soluble species, dry deposition and lightning as a source of trace atmospheric gases.
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Kasting JF, Walker JCG. Limits on oxygen concentration in the prebiological atmosphere and the rate of abiotic fixation of nitrogen. ACTA ACUST UNITED AC 1981. [DOI: 10.1029/jc086ic02p01147] [Citation(s) in RCA: 132] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Pinto JP, Gladstone GR, Yung YL. Photochemical Production of Formaldehyde in Earth's Primitive Atmosphere. Science 1980; 210:183-5. [PMID: 17741284 DOI: 10.1126/science.210.4466.183] [Citation(s) in RCA: 135] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Formaldehyde could have been produced by photochemical reactions in Earth's primitive atmosphere, at a time when it consisted mainly of molecular nitrogen, water vapor, carbon dioxide, and trace amounts of molecular hydrogen and carbon monoxide. Removal of formaldehyde from the atmosphere by precipitation can provide a source of organic carbon to the oceans at the rate of 10(11) moles per year. Subsequent reactions of formaldehyde in primeval aquatic environments would have implications for the abiotic synthesis of complex organic molecules and the origin of life.
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