Monday, June 24, 2013

Early Biotic Phosphorus Enrichment

 A nice enough idea, but not one that I think that we can easily accept unless we can show a creditable scarcity in the primordial crust and that is not done here. More plausibly, early life was great at laying down phosphorus enrichment that it naturally collected and it simply did not release so easily.

We also note that prebiotic phosphorus was actively supplied by comet bombardment as per this paper by Macia and Henandez dated 1996. Thus it is not a new idea, but the actual enrichment is the real question which is much better solved by initial limitations of the biota itself.

Besides, once you skip the biotic aspect, everything on earth came in by way of meteorite.

Life-producing phosphorus was carried to Earth by meteorite

June 16, 2013 - Scientists may not know for certain whether life exists in outer space, but new research from a team of scientists led by a University of South Florida astrobiologist now shows that one key element that produced life on Earth was carried here on meteorites.

In an article published in the new edition of the Proceedings of the National Academies of Sciences, USF Assistant Professor of Geology Matthew Pasek and researchers from the University of Washington and the Edinburg Centre for Carbon Innovation, revealed new findings that explain how the reactive phosphorus that was an essential component for creating the earliest life forms came to Earth.

The scientists found that during the Hadean and Archean eons – the first of the four principal eons of the Earth's earliest history – the heavy bombardment of meteorites provided reactive phosphorus that when released in water could be incorporated into prebiotic molecules. The scientists documented the phosphorus in early Archean limestone, showing it was abundant some 3.5 billion years ago.

The scientists concluded that the meteorites delivered phosphorus in minerals that are not seen on the surface of the Earth, and these minerals corroded in water to release phosphorus in a form seen only on the early Earth.

The discovery answers one of the key questions for scientist trying to unlock the processes that gave rise to early life forms: Why don't we see new life forms today?

"Meteorite phosphorus may have been a fuel that provided the energy and phosphorus necessary for the onset of life," said Pasek, who studies the chemical composition of space and how it might have contributed to the origins of life. "If this meteoritic phosphorus is added to simple organic compounds, it can generate phosphorus biomolecules identical to those seen in life today."

Pasek said the research provides a plausible answer: The conditions under which life arose on the Earth billions of years ago are no longer present today.

December 1997, Volume 27, Issue 5-6, pp 459-480
Primary Sources of Phosphorus and Phosphates in Chemical Evolution
  • E. Maciá*, 
  • M. V. Hernández, 
  • J. OróIn this work we consider the role of phosphorus in chemical evolution from an interdisciplinary approach. First we briefly review the presence of this element in different cosmic sites, such as massive stellar cores, circumstellar and interstellar clouds, meteorites, lunar and Martian samples, interplanetary dust particles, cometary dust and planetary atmospheres. Thus we illustrate the fact that phosphorus seems to be, at the same time, scarce and ubiquitous in the solar system. Afterwards, by comparing the phosphorus content of our planet's main reservoirs with the amount of cometary and meteoritic matter captured by the primitive Earth, we conclude that comets may have provided a primary source for phosphorus compounds of prebiotic interest. Finally, we make a number of proposals aimed to gain observational supporting evidence to the above conclusion and other suggestions made in the article.

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