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TEMPE, Ariz. Scientists from around the world have reconstructed changes in Earths ancient ocean chemistry during a broad sweep of geological time, from about 2.5 to 0.5 billion years ago. They have discovered that a deficiency of oxygen and the heavy metal molybdenum in the ancient deep ocean may have delayed the evolution of animal life on Earth for nearly 2 billion years.
The findings, which appear in the March 27 issue of Nature, come as no surprise to Ariel Anbar, one of the authors of the study and an associate professor at Arizona State University with joint appointments in the Department of Chemistry and Biochemistry and the School of Earth and Space Exploration in the College of Liberal Arts and Sciences. The study was led by Clint Scott, a graduate student at University of California Riverside. Scott works with Timothy Lyons, a professor of biogeochemistry at UCR who is a long-time collaborator of Anbars and also an author of the paper.
Clints data are an important new piece in a puzzle weve been trying to solve for many years, says Anbar. Tim and I have suspected for a while that if the oceans at that time were oxygen deficient they should also have been deficient in molybdenum. Weve found evidence of that deficiency before, at a couple of particular points in time. The new data are important because they confirm that those points were typical for their era.
Molybdenum is of interest to Anbar and others because it is used by some bacteria to convert the element nitrogen from a gas in the atmosphere to a form useful for living things a process known as nitrogen fixation. Bacteria cannot fix nitrogen efficiently when they are deprived of molybdenum. And if bacteria cant fix nitrogen fast enough then eukaryotes a kind of organism that includes plants, pachyderms and people are in trouble because eukaryotes cannot fix nitrogen themselves at all.
If molybdenum was scarce, bacteria would have had the upper hand, con
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| Contact: Nikki Staab nstaab@asu.edu 480-727-9329 Arizona State University Source:Eurekalert |