Electrochemical studies of iron meteorites: phosphorus redox chemistry on the early Earth

BRYANT, D. E., GREENFIELD, D., WALSHAW, R. D., EVANS, S. M., NIMMO, A. E., SMITH, C. L., WANG, L. M., PASEK, M. A. and KEE, T. P. (2009). Electrochemical studies of iron meteorites: phosphorus redox chemistry on the early Earth. International Journal of Astrobiology, 8 (1), 27-36.

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Abstract

The mineral schreibersite, (Fe,Ni)(3)P, a ubiquitous component of iron meteorites. is known to undergo anoxic hydrolytic modification to afford a range Of phosphorus oxyacids. H-phosphonic acid (H3PO3) is the principal hydrolytic product under hydrothermal conditions, as confirmed here by P-31-NMR spectroscopic studies oil shavings of the Seymchan pallasite (Magadan, Russia, 1967), but in the presence of photochemical irradiation I more reduced derivative, H-phosphinic (H3PO2) acid, dominates. The significance Of Such lower oxidation state oxyacids of phosphorus to prebiotic chemistry upon the early Earth lies with the facts that Such forms Of Phosphorus are considerably more Soluble and chemically reactive than orthophosphate, the commonly found form of phosphorus oil Earth, thus allowing nature a mechanism to circumvent the so-called Phosphate Problem. This paper describes the Galvanic corrosion of Fe3P, a hydrolytic modification pathway for schreibersite, leading again to H-phosphinic acid as the key P-containing product. We envisage this pathway to be highly significant within a meteoritic context as iron meteorites are polymetallic composites in which dissimilar metals, with different electrochemical potentials, are connected by all electrically conducting matrix. In the presence of a Suitable electrolyte medium, i.e., salt water, galvanic corrosion call take place. In addition to model electrochemical studies, we also report the first application of the Kelvin technique to map surface potentials of a meteorite sample that allows the electrochemical differentiation of schreibersite inclusions Within an Fe:Ni matrix. Such experiments, coupled with thermodynamic calculations, may allow LIS to better understand the chemical redox behaviour of meteoritic components with early Earth environments.

Item Type:	Article
Additional Information:	3rd Conference of the Astrobiology-Society-of-Britain JUL 01-04, 2008 Univ Glamorgan, Glamorgan, WALES
Research Institute, Centre or Group - Does NOT include content added after October 2018:	Materials and Engineering Research Institute > Structural Materials and Integrity Research Centre > Centre for Corrosion Technology
Identification Number:	https://doi.org/10.1017/S1473550408004345
Page Range:	27-36
Depositing User:	Ann Betterton
Date Deposited:	11 Feb 2010 16:31
Last Modified:	18 Mar 2021 10:00
URI:	https://shura.shu.ac.uk/id/eprint/1094

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