Supply of phosphate to early Earth by photogeochemistry after meteoritic weathering

Abstract

During terrestrial differentiation, the relatively small amount of phosphorus that migrated to the lithosphere was incorporated into igneous rock, predominantly in the form of basic calcium orthophosphate (Ca 10 (PO 4 ) 6 (OH,F,Cl) 2 , apatite). Yet, the highly insoluble nature of calcium apatite presents a significant problem to those contemplating the origin of life given the foundational role of phosphate (PO 4 3- ) in extant biology and the apparent requirement for PO 4 3- as a catalyst, buffer and reagent in prebiotic chemistry. Reduced meteorites such as enstatite chondrites are highly enriched in phosphide minerals, and upon reaction with water these minerals can release phosphorus species of various oxidation states. Here, we demonstrate how reduced phosphorus species can be fully oxidized to PO 4 3- simply by the action of ultraviolet light on H 2 S/HS - . We used low pressure Hg lamps to simulate UV output from the young Sun and 31 P NMR spectroscopy to monitor the progress of reactions. Our experimental findings provide a cosmochemically and geochemically plausible means for supply of PO 4 3- that was widely available to prebiotic chemistry and nascent life on early Earth, and potentially on other planets.

UV-Induced Nanoparticles-Formation, Properties and Their Potential Role in Origin of Life

“…3− anion from phosphorus species upon ultraviolet light in the presence of H 2 S/HS − [72]. These experiments show that PO 4 3− was widely available to prebiotic chemistry and nascent life on early Earth and potentially on other planets.…”

“…The pH in the early environment might have been also stabilized by phosphate buffer similarly with our experimental arrangement. The Recent study of Ritson, Mojzsis and Sutherland demonstrates the formation of PO 4 3− anion from phosphorus species upon ultraviolet light in the presence of H 2 S/HS − [ 72 ]. These experiments show that PO 4 3− was widely available to prebiotic chemistry and nascent life on early Earth and potentially on other planets.…”

Lightning strikes as a major facilitator of prebiotic phosphorus reduction on early Earth

“…When wetted, schreibersite forms hydrous, activated phosphate capable of forming key basic organic molecules, such as glycerol phosphate, nucleosides and phosphocholine 8 , 9 , and intermediate phosphorus species, such as hypophosphite (H 2 PO 2 − ) and phosphite (HPO 3 2− ) 5 , 10 . While such intermediate phosphorous species would hinder organic reactions, they may still play an important role in the origin of life by efficiently reacting with solar ultraviolet (UV) radiation and dissolved HS − to form orthophosphate (PO 4 3− ) 11 . Thus, schreibersite is one commonly accepted source of phosphate for the terrestrial prebiotic synthesis of essential organic phosphate molecules 11 – 13 .…”

“…While such intermediate phosphorous species would hinder organic reactions, they may still play an important role in the origin of life by efficiently reacting with solar ultraviolet (UV) radiation and dissolved HS − to form orthophosphate (PO 4 3− ) 11 . Thus, schreibersite is one commonly accepted source of phosphate for the terrestrial prebiotic synthesis of essential organic phosphate molecules 11 – 13 .…”

Serpentinization as a route to liberating phosphorus on habitable worlds

“…In addition to these intrinsic sources of phosphorus, extrinsic sources such as meteorites may have delivered P to the early earth, primarily as metal phosphides [28][29][30][31][32][33]. The advantage of such a source is that the reaction of water with phosphides liberates P as the ion phosphite (HPO 3 2− ) in which the oxidation state of P is + 3 as opposed to + 5.…”