Abiotic Synthesis Research Articles

Pre-biotic organic matter from comets and asteroids.

Several authors have suggested that comets or carbonaceous asteroids contributed large amounts of organic matter to the primitive Earth, and thus possibly played a vital role in the origin of life. But organic matter cannot survive the extremely high temperatures (>10(4) K) reached on impact, which atomize the projectile and break all chemical bonds. Only fragments small enough to be gently decelerated by the atmosphere--principally meteors of 10(-12)-10(-6) g--can deliver their organic matter intact. The amount of such 'soft-landed' organic carbon can be estimated from data for the infall rate of meteoritic matter. At present rates, only approximately 0.006 g cm-2 intact organic carbon would accumulate in 10(8) yr, but at the higher rates of approximately 4 x 10(9) yr ago, about 20 g cm-2 may have accumulated in the few hundred million years between the last cataclysmic impact and the beginning of life. It may have included some biologically important compounds that did not form by abiotic synthesis on Earth.

Abiotic Synthesis of Amino Acids by Proton Irradiation of a Mixture of Carbon Monoxide, Nitrogen, and Water

Abstract We have shown that proton irradiation simulating the action of cosmic rays and solar flare particles formed proteinous and non-proteinous amino acids such as glycine, alanine, aspartic acid and β-alanine from a mixture of carbon monoxide, carbon dioxide, nitrogen and water. The yield of amino acids per unit energy was the highest obtained among various prebiotic energy sources used. This result suggests the possibility of the formation of amino acids from mildly reduced primitive atmospheres on the earth.

Origin of precursors of organic molecules during evaporation of meteorites and mafic terrestrial rocks

THE accretion of the Earth was characterized by high-temperature transformations of planetesimal matter during high-velocity impacts. In the final stages of the Earth's growth, up to 30% of planetesimal mass and the corresponding mass of the target were evaporated1-3. Here we look at the effect of laser-pulse heating on meteorite materials and silicates in order to simulate the vaporization which occurs during impacts and to study the chemical composition of the gases produced. In our experiments, the residual gas mixture consisted of both oxidized and reduced components: CO, CO2, SO2, H2O, H2, N2, H2S, COS, CS2, various hydrocarbons from C1 to C6, HCN and CH3CHO. In addition, we find that the composition of the gas mixtures is qualitatively similar for all samples. Our data give an idea of the chemical composition of gases that may have been released into the Earth's early atmosphere by impact devolatilization. In the gas mixtures produced by these experiments we measured weight per cents of ∼10−3 for HCN, ∼10−4 for CH3CHO and ∼10−2 for hydrocarbons. Impact vaporization is no less effective for the formation of HCN than is the formation of HCN by impact reprocessing of the atmosphere4. For the production of aldehyde and hydrocarbons, impact vaporization is even more effective. The gas mixtures formed by vaporization of silicates provide favourable conditions for abiotic synthesis of organic compounds.

Geochemical constraints on the abiotic synthesis of organic compounds in hydrothermal systems

Geochemical constraints on the abiotic synthesis of organic compounds in hydrothermal systems

Modelling of abiotic synthesis of low-molecular polyols as structural units of biological membranes

Modelling of abiotic synthesis of low-molecular polyols as structural units of biological membranes

Abiotic synthesis of nucleic acid bases by electric discharge in a simulated primitive atmosphere

Abiotic synthesis of nucleic acid bases by electric discharge in a simulated primitive atmosphere

Thermodynamics of the abiotic synthesis of aqueous organic species at high temperatures

Thermodynamics of the abiotic synthesis of aqueous organic species at high temperatures

Abiotic synthesis of organic gases and aerosols in the atmosphere of titan

Abiotic synthesis of organic gases and aerosols in the atmosphere of titan

Chemical effects of large impacts on the Earth's primitive atmosphere.

Intense bombardment of the moon and terrestrial planets approximately 3.9-4.0 x 10(9) years ago could have caused the chemical reprocessing of the Earth's primitive atmosphere. In particular, the shock heating and rapid quenching caused by the impact of large bodies into the atmosphere could produce molecules such as HCN and H2CO4 which are important precursors for the abiotic synthesis of complex organic molecules. Here we model the production of HCN and H2CO by thermochemical equilibrium and chemical kinetic calculations of the composition of shocked air parcels for a wide range of temperatures, pressures and initial compositions. For atmospheres with C/O > or = 1, our results suggest that bolide impacts cause HCN volume mixing ratios of approximately 10(-3) to 10(-5) in the impact region and global average ratios of 10(-5) to 10(-12). The corresponding H2CO mixing ratios in the impact region are 10(-7) to 10(-9); no-global mixing can occur, however, as H2CO is rapidly destroyed or rained out of the atmosphere within days to hours. Rainout to the oceans of 3-15% of the HCN produced can provide approximately (3-14) x 10(11) mol HCN per year. This is somewhat larger than other predicted sources of HCN and H2CO on the primitive Earth.

Submarine hydrothermal vents and associated gradient environments as sites for the origin and evolution of life

Submarine hydrothermal vents are the only comtemporary geological environment which may be called truly primeval; they continue to be a major source of gases and dissolved elements to the modern ocean as they were to the Archean ocean. Then, as now, they encompassed a multiplicity of physical and chemical gradients as a direct result of interactions between extensive hydrothermal activity in the Earth's crust and the overlying oceanic and atmospheric environments. We have proposed that these gradients provided the necessary multiple pathways for the abiotic synthesis of chemical compounds, origin and evolution of ‘precells’ and ‘precell’ communities and, ultimately, the evolution of free-living organisms. This hypothesis is consistent with the tectonic, paleontological, and degassing history of the earth and with the use of thermal energy sources in the laboratory to synthesize amino acids and complex organic compounds. In this paper, we expand upon the geophysical, chemical, and possible microbiological analogies between contemporary and Archean hydrothermal systems and suggest several hypotheses, related to our model for the origin and evolution of life at Archean vents, which can be tested in present-day hydrothermal systems.

The catalytic power of inorganic components in the abiotic synthesis of hydroquinone-derived humic polymers

The catalytic power of 14 inorganic materials, namely, 4 synthetic short-range ordered oxides, 4 CBD-treated clay minerals, and 6 primary minerals in the abiotic synthesis of humic acids (HA) through the oxidative polymerization of hydroquinone was investigated. The promoting effect of Mn oxide is much higher than that of short-range ordered oxides of Fe, Al and Si. The accelerating effects of montmorillonite and tephroite are highest among the respective mineral groups studied. Among all inorganic materials studied, the catalytic power of tephroite (Mn 2SiO 4) and especially Mn oxide is most striking. The Mn oxide and tephroite rapidly convert hydroquinone to HA and the IR spectra of these synthesized HA are similar to those of soil HA. Compared to the clay minerals, the transition metal-bearing primary minerals have a stronger promoting effect on the synthesis of hydroquinone-derived HA. The data obtained indicate the sequence of the catalytic power of selected short-range ordered oxides, clay minerals, and primary minerals in the formation of hydroquinone-derived HA. The powerful promoting effects of the Mn oxide and tephroite on the synthesis of HA strongly indicate that Mn-bearing oxides and silicates deserve close attention in the formation of humic substances.

Abiotic formation of oligonucleotides on basalt surfaces

The complication and further evolution of abiotic syntheses products occurred under environmental influences at the prebiological stage. From this point of view, the influence of some types of irradiation on the organic molecules adsorbed on the surfaces of volcanic rocks, appeared to be of great importance. In this connection, the effect of gamma rays on the AMP molecules adsorbed on mineral surfaces such as cinders and ashes has been studied. It has been shown that they can polymerize with the formation of oligonucleotides. The treatment of oligomers obtained by venom phosphodiesterase has shown that a polymeric product has mainly 3′–5′ and 2′–5′ bonds between nucleotides. The results obtained have been discussed from the evolutionary aspect.

The origin of the genetic code

The problem of code origin is presented in the context of increasingly complex events in the origin of life. The likely sequence of events appears to progress from abiotic synthesis of biological monomers to polymers to formation of protocells, which would be capable of competition and further evolution. We propose that rate of polymer formation was a critical controlling parameter of rate of protocell propagation. This would lead to selection of autocatalytic and mutually catalytic reactions of polymer formation. Primitive proteins would catalyze polynucleotide formation, and polynucleotides could be used as anvils of noncoded polypeptide synthesis. Proteins that could catalyze this latter reaction (assignment catalysts) would play an important role in subsequent evolution of a genetic code. Competing populations of assignment catalysts would possess very nonlinear dynamics of production of the catalysts themselves. An analysis of this dynamics shows that it has a rich family of bifurications which would provide a pathway for gradual approach to a genetic code. The selection criterion in this process would be efficiency of utilization of monomers and energy for the production of assignment catalysts.

Abiotic synthesis of organic molecules from minerals containing traces of dissolved H2O, CO2 and N2 part I: Basic principles

Oxides and silicates which crystallize in the presence of H2O, CO2 and N2, especially at high pressures, are expected to dissolve traces of these fluid components. In doing so atomic and electronic rearrangements occur between the host lattice and the dissolved molecules which lead to different solute species. These may be simply hydroxyl OH−, carbonate CO3 2− of similar ions, but other species can also form which are chemically reduced such as molecular H2, CO2 2− and CO− or oxidized such as peroxy ions, O2 2−. When the minerals containing such solute species are decompressed and cooled, they eventually become supersaturated with respect to their dissolved impurities. If the relative mobilities of the different solute species are different, diffusion and subsurface segregation lead to spatial separation: the surface and subsurface zone become enriched in the reduced species while the oxidized species remain in the bulk. Upon heating or during chemical dissolution (weathering) the reduced species contained in the surface react leading to the formation of a wide variety of H−C−O−N molecules: not only H2O, CO2 and possibly N2 but also organic molecules. No external reduced atmosphere is needed, according to this hypothesis.

Abiotic synthesis of organic molecules from minerals containing traces of dissolved H2O, CO2 and N2 part II: Experimental data

Even though a given mineral, for instance olivine, may contain only traces of dissolved H2O, CO2 and N2 the gases which evolve from its surface during heating comprise (a) highly reduced molecules such as H2, CH4, CmHn and more complex hydrocarbons, HCN and other N-bearing compounds (b) oxidized species in various degrees of oxidation from formaldehyde and CO to oxygen. These gases evolve sequentially besides H2O, CO2 and possibly N2, their relative amounts being controlled by experimental parameters such as the rate of heating. Preliminary indications of amino acids have been obtained by liquid extraction. The chemical complexity is a consequence of radical reactions between different solute species in the surface and the bulk of the mineral grains. Data for synthetic MgO and for mantle-derived olivine are presented.

Polycyclic aromatic hydrocarbons in the Murchison meteorite

More than thirty polycyclic aromatic hydrocarbons, including nine heterocyclic aromatic compounds, have been identified in solvent extracts of the Murchison meteorite by gas chromatography-mass spectrometry using bonded-phase fused silica columns. Structural isomers of several alkylated aromatic hydrocarbons, including methylpyrene and methylphenanthrene were chromatographically separated, thus allowing calculations of the amount of alkyl substituted compounds in the solvent extracts. The ratio of odd-carbon number to even-carbon number was found to be approximately 0.1. Based on these data and literature data from model pyrolysis experiments, a temperature of 1000°C is suggested for the formation of polycyclic aromatic hydrocarbons in the solar nebula or premeteoritic body. The value of 1000°C is within the range of temperatures for the condensation of the nebular material from the initial high temperature phases to the lower temperature phases at which chemical and isotopic equilibria were frozen. A simple model for the abiotic synthesis of heterocyclic compounds from simple aliphatic precursors is also presented.

On the reported optical activity of amino acids in the Murchison meteorite

In analyses of extracts from the Murchison meteorite (a carbonaceous chondrite), Engel and Nagy1 reported an excess of L-enantiomers for several protein amino acids but found that the non-protein amino acids were racemic. They suggested that the excess of L-isomers might have resulted from an asymmetric synthesis or decomposition. Their results disagree with those obtained previously2–4 and they claim this is due to improved methodology. In fact, their extraction method and analytical procedure (gas chromatography–mass spectrometry, GC–MS) was similar to those used in the original report2 of amino acids in the Murchison meteorite except that they used specific ion monitoring in the GC–MS measurements. We found the results of Engel and Nagy odd in that likely contaminants (the protein amino acids ala, leu, glu, asp and pro) were nonracemic while unlikely contaminants (isovaline and α-amino-n-butyric acid) were racemic. For example, Engel and Nagy report that the leucine is ∼90% L-enantiomer in the water-extracted sample whereas isovaline (α-methyl-α-aminobutyric acid) is racemic. It would be most unusual for an abiotic stereoselective decomposition or synthesis of amino acids to occur with protein amino acids but not with non-protein amino acids. We now show here that the explanation of terrestrial contamination is consistent with their results and is much more probable.

Comment on “Submarine hot springs: Origin of life?”] Hydrothermal vents revisited

It was gratifying to read Peter Bell's synopsis of our paper [Corliss et al., 1981] in the March 23 issue of Eos (Submarine hot springs: Origin of life?) however, in the last sentence, he wrote, ‘They note that microorganisms found in recent expeditions to the submarine hot springs of the East Pacific Rise would be evidence that the processes are still occurring.’In our final paragraph we actually said that while “events leading to the formation of complex organic compounds and “protocell” structures may still be occurring in present‐day oceanic hydrothermal systems … the complex communities of bacteria in modern oceanic environments would outcompete and consume abiotically synthesized protocells…” Modern‐day vent microbiota will probably mask or destroy any evidence for abiotic synthesis in the hydrothermal vents.

Abiotic organic synthesis in space

A model of iron meteorite formation at low temperature (250°C) in space (e.g. comets) has been experimentally investigated. A Fe(CO)5 + Ni(CO)4 + H2S gas stream was heated (180°C) between the poles of a permanent magnet. Iron-nickel alloys similar to natural meteorites were formed (Kamazit,Taenit enveloping Troilite and Pentlandit). In addition graphite and hydrocarbons were tentatively recognized. This finding is supported by technical literature on the Fischer-Tropsch synthesis where the decompositiog of metalcarbonyls in presence of H2 and NH3 at 240°C leads to hydrocarbons and primary amines. It is assumed that in a magnetic field the streaming gas-mixture might react to form some assymetric, not completely racemic compounds. Such compounds could have reached earth with impacting comets and meteorites.

Photochemical Production of Formaldehyde in Earth's Primitive Atmosphere

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.