International team of scientists discover clue to delay of life on Earth

In today’s high-oxygen world, molybdenum is the most abundant transition metal in the oceans. That is because the primary source of molybdenum to the ocean is the reaction of oxygen with molybdenum-bearing minerals in rocks. So the hypotheses rode on the idea that the amount of molybdenum in the oceans should track the amount of oxygen. To test that idea, Scott, Lyons and Anbar examined rock samples from ancient seafloors by dissolving them in a cocktail of acids and analyzing the rock for molybdenum content using a mass spectrometer. Many of these analyses were carried out using state-of-the art instrumentation in the W. M. Keck Foundation Laboratory for Environmental Biogeochemistry at Arizona State University. The scientists found significant evidence for a molybdenum-depleted ocean relative to the high levels measured in modern, oxygen-rich seawater.

By studying Earth’s ancient oceans, atmosphere and biology we can test how well we understand the modern environment, according to Anbar. “Our molybdenum hypothesis was inspired by the theory that biology in the oceans today is often starved for a different metal – iron – and that the lack of iron in parts of the oceans affects the transfer of the greenhouse gas carbon dioxide from the atmosphere to the ocean” he says. “The idea that metal deficiency in the oceans can affect the entire planet is very powerful. Here, we are exploring the limits of that idea by seeing if it can solve ancient puzzles. These new findings strengthen our confidence that it can.”

Anbar, Lyons and Scott were joined in the research by A. Bekker of the Carnegie Institution of Washington, D.C.; Y. Shen of the University du Quebec a Montreal; S.W. Poulton of Newcastle University, Newcastle upon Tyne, United Kingdom; and X. Chu of the Chinese Academy of Sciences, Beijing, China. The research was supported by grants from the U.S. National Science Foundation Division of Earth Sciences and the NASA Astrobiology Program.

This new publication in Nature follows on the heels of two related papers published in Science last September by Anbar, Lyons, Scott and other colleagues: http://clas.asu.edu/newsevents/newsreleases/2007/oxygenwhiff_09272007.htm

ASU SOURCE:
Ariel Anbar,
480-965-0767

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Iqbal Pittalwala,
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ASU MEDIA CONTACTS:
Jenny Green,
Department of Chemistry and Biochemistry
http://chemistry.asu.edu/
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Arizona State University
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