Posted by: Saving Water SA (Cape Town, South Africa) – partnered with Water Rhapsody conservation systems – 14 May 2010
Tiny variations in the isotopic composition of silver in meteorites and Earth rocks are helping scientists put together a timetable of how our planet was assembled, beginning 4.568 billion years ago.
Results of a new study, funded by the National Science Foundation (NSF) and published this week in the journal Science, indicate that water and other key volatiles may have been present in at least some of Earth’s original building blocks, rather than acquired later from comets, as some scientists have suggested.
“These results have significant implications for our understanding of the processes that accompanied accretion and formation of the proto-Earth, and the means by which volatile-rich materials like water were acquired,” says Stephen Harlan, program director in NSF’s Division of Earth Sciences. “Water may have been present since very early in the history of our planet.”
Compared to the solar system as a whole, Earth is depleted in volatile elements, such as hydrogen, carbon, and nitrogen, which likely never condensed on planets formed in the inner, hotter, part of the solar system.
Earth is also depleted in moderately volatile elements, such as silver.
“A big question in the formation of the Earth is when this depletion occurred,” says paper co-author Richard Carlson of the Carnegie Institution for Science in Washington, D.C. “That’s where silver isotopes can really help.” Continue reading