Natural Radioactive Environments As Sources of Local Disequilibrium for the Emergence of Life

Autor(es)

Altair, Thiago ^{[1, 2, 3]} ; Sartori, Larissa M. ^[4] ; Rodrigues, Fabio ^[5] ; de Avellar, Marcio G. B. ^[6] ; Galante, Douglas ^{[1, 2]}

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Fis Sao Carlos, Sao Carlos - Brazil

^[2] Brazilian Ctr Res Energy & Mat CNPEM, Brazilian Synchrotron Light Lab LNLS, Av Giuseppe Maximo Scolfaro 10000, BR-13083100 Campinas, SP - Brazil

^[3] Univ Sao Paulo, Inst Quim Sao Carlos, Sao Carlos - Brazil

^[4] Univ Sao Paulo, Inst Matemat & Estat, Sao Paulo - Brazil

^[5] Univ Sao Paulo, Inst Quim, Dept Quim Fundamental, Sao Paulo - Brazil

^[6] Univ Fed Sao Paulo, Inst Ciencias Ambientais Quim & Farmaceut, Diadema - Brazil

• Tipo de documento: Artigo Científico
• Fonte: ASTROBIOLOGY; v. 20, n. 12 SEP 2020.
• Citações Web of Science: 0

Resumo

Certain subterranean environments of Earth have naturally accumulated long-lived radionuclides, such as(238)U,Th-232, and(40)K, near the presence of liquid water. In these natural radioactive environments, water radiolysis can produce chemical species of biological importance, such as H-2. Although the proposal of radioactive decay as an alternative source of energy for living systems has existed for >30 years, this hypothesis gained strength after the recent discovery of a peculiar ecosystem in a gold mine in South Africa, whose existence is dependent on chemical species produced by water radiolysis. In this study, we calculate the chemical disequilibrium generated locally by water radiolysis due to gamma radiation. We then analyze the possible contribution of this disequilibrium for the emergence of life, considering conditions of early Earth and having as reference the alkaline hydrothermal vent theory. Results from our kinetic model point out the similarities between the conditions caused by water radiolysis and those found on alkaline hydrothermal systems. Our model produces a steady increase of pH with time, which favors the formation of a natural electrochemical gradient and the precipitation of minerals with catalytic activity for protometabolism in this aqueous environment. We conclude by describing a possible free-energy conversion mechanism based on protometabolism, which could be a requisite for the emergence of life in Hadean Earth. (AU)

• Processo FAPESP: 16/08854-7 - Ambientes radioativos naturais como fontes de desequilíbrio químico local e suas potenciais implicações prebióticas
• Beneficiário: Thiago Altair Ferreira
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 16/06114-6 - O Sistema Terra e a evolução da vida durante o Neoproterozoico
• Beneficiário: Ricardo Ivan Ferreira da Trindade
• Modalidade de apoio: Auxílio à Pesquisa - Temático