Volcanic processes and synthesis of simple organic compounds on primitive Earth


Development of the models of organic compounds evolution on the primitive Earth based on the continuity principle [1] is of particular interest for the study of the origins of life, and any proposed model should not be contradictory from the viewpoint ofevolutional planetology and chemistry. At present it is usually assumed that in the monomer synthesis the major energy sources were the ultra-violet solar radiation, electric discharges and shock waves. The concentrations of organic compounds in the primitive ocean that have been formed by the ultra-violet solar radiation have been estimated. The concentrations obtained scatter over a wide range. Sagan [2] assumes that 1% solution of amino acids and oxi-acids could be formed in 109 years. Abelson [3] drew attention to the H C N hydrolysis processes which result the formation of N H 4 O H and HCOOH. Assuming that the primitive ocean volume was 1022 ml, the author has obtained the highly diluted solution of H C N (10 4 M). In this case the stationary concentrations of amino acids will prove to be on the order of about 10-6 M. On the other hand Hull [4] showed that taking photochemical destruction processes into account, stationary concentrations of organic compounds in the primitive ocean would be much too low (i0 12 M). The problem on photodestruction of organic molecules in the primitive Earth's atmosphere should be solved more generally based on the vertical transfer in the atmosphere. If it is assumed that nitrogen and argon are the main components of the primitive atmosphere and carbon dioxide and water concentrations do not exceed the up-to-date values then the ozone concentration is about 10-2 from the concentration available. It means that absorption in the region 1700 A 3000 was insignificant and the ultraviolet radiation flux with 2 ~ 3000 /~ was equalled to ~ 1015 cm2 sec1. The flux with 2 ~ 1700 A is 5 9 1011 cm2 sec1, respectively. Energy range of the ultraviolet radiation with these wavelengths is 7.3 ev 4.13 ev. As known energies of the most important bonds in organic chemistry have the following values [t7]; C -C : 8.4 ev; C O : 7.4 ev; O H : 4.8 ev; C H : 4.3 ev; N M : 4.1 ev; C O : 3.7 ev; C-C: 6.4 ev, etc. It is easily to see that the ultraviolet radiation of the Sun should destruct molecules synthesized due to the long wave UV, of the shock waves and electric discharges. The molecule lifetime in the atmosphere from generation to photodestruction can be estimated by the order of magnitude as follows: r destr. 1 0(pa' where ~ is the photodissociation section, ~o is the photon flux, 0 quantum

DOI: 10.1007/BF00927931

7 Figures and Tables

Cite this paper

@article{Mukhin1976VolcanicPA, title={Volcanic processes and synthesis of simple organic compounds on primitive Earth}, author={L . M . Mukhin}, journal={Origins of life}, year={1976}, volume={7}, pages={355-368} }