The Effects of Ferrous and other Ions on the Abiotic Formation of Biomolecules using Aqueous Aerosols and Spark Discharges

Abstract

It has been postulated that the oceans on early Earth had a salinity of 1.5 to 2 times the modern value and a pH between 4 and 10. Moreover, the presence of the banded iron formations shows that Fe(+2) was present in significant concentrations in the primitive oceans. Assuming the hypotheses above, in this work we explore the effects of Fe(+2) and other ions in the generation of biomolecules in prebiotic simulation experiments using spark discharges and aqueous aerosols. These aerosols have been prepared using different sources of Fe(+2), such as FeS, FeCl(2) and FeCO(3), and other salts (alkaline and alkaline earth chlorides and sodium bicarbonate at pH = 5.8). In all these experiments, we observed the formation of some amino acids, carboxylic acids and heterocycles, involved in biological processes. An interesting consequence of the presence of soluble Fe(+2) was the formation of Prussian Blue, Fe(4)[Fe(CN)(6)](3), which has been suggested as a possible reservoir of HCN in the initial prebiotic conditions on the Earth.

Primordial synthesis of amines and amino acids in a 1958 Miller H 2 S-rich spark discharge experiment

“…The volcanic apparatus differed from Miller's classic apparatus in that it utilized an aspirator that injected steam into the electric discharge chamber, simulating a volcanic eruption (1). These results, combined with the findings that aqueous aerosols in the presence of spark discharges effectively produce abiotic organic compounds (11,12), verified how readily prebiotic organics could have been synthesized on the primeval Earth in localized volcanic environments rich in lightning and steam (13,14).…”

Thermal Wet Decomposition of Prussian Blue: Implications for Prebiotic Chemistry

“…In a recent work, we demonstrated that Prussian Blue is easily formed in spark-discharge experiments using saline aerosols of ferrous salts [10]. Therefore, the formation of Prussian Blue offers a mechanism for the concentration of cyanide in the form of the ferrocyanide ion.…”

Prebiotic Synthesis of Protobiopolymers Under Alkaline Ocean Conditions

“…As a reference experiment, we used saline aerosols at pH=5.8 (Experiment 2), and as control experiments, we used aqueous aerosols of pure water at neutral pH. Details about the reference and control experiments are reported in Ruiz-Bermejo et al (2007b) and RuizBermejo et al (2007a), respectively. Five experiments for each pH value were carried out ( Fig.…”

“…A 500-ml glass reactor was filled with a gas mixture containing CH 4 :N 2 :H 2 (40:30:30), purchased from Praxair, and 5 mL of a saline solution 1.5 times the concentration of sea water [0.63 M NaCl, 0.18 M MgCl 2 , 0.015 M KCl, 0.02 M NaHCO 3 (Morse and Mackenzie 1998;Ruiz-Bermejo et al 2007b) adjusted to various pH levels: Experiment 1, pH=4 with HCl (Russell and Hall 1997). Experiment 2, reference experiment, pH=5.8 with HCl (Morse and Mackenzie 1998).…”

“…In such a case, aerosols and salts would act in synergy in the prebiotic synthesis of organic compounds. In this context, we tested the effect of saline aqueous aerosols in the formation of bioorganic compounds under plausible prebiotic conditions (Ruiz-Bermejo et al 2007b). For that test, aqueous solutions with a salinity 1.5 times the concentration of actual sea water, the likely concentration of the ancient sea, and a pH=5.8 (Knauth 2005;Morse and Mackenzie 1998) were used.…”