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Geobiology: November 2011


Follow the Uranium

Researchers from NAI's Arizona State University Team and NASA's Exobiology Program have developed a novel geochemical tool that compares the partitioning of uranium isotopes from seawater into carbonates. A decrease of uranium in seawater is indicative of a lack of oxygen (anoxia) in the ocean.

For the first time ever, this approach has revealed the quantitative levels of dissolved oxygen in ancient oceans at the time of Earth's largest mass extinction, known as the end-Permian mass extinction, 252 million years ago. Many leading scientific theories on the cause of this catastrophe are based on the assumption of a long-term existence of ocean anoxia before the extinction event itself.

The study began by obtaining a core sample of carbonate rock collected in Dawen in Southern China. This location is known to physically correlate with the Permian-Triassic boundary. The investigators focused upon the strata around the so-called "Extinction Horizon," or, the "moment" of the mass extinction. This study has quantified the amount of oxygen across the extinction event in the ancient global oceans. Most critically, it revealed that ocean anoxia existed for a much shorter period of time (~10,000 years) before the extinction event than was previously estimated (>100,000 years). This new insight greatly constrains possible explanations for the cause of the mass extinction event. The team's paper is published in a recent issue of PNAS.

Source: NAI Newsletter

Scouting for Astrobiology

When Dr. Eric Boyd of the NAI's Montana State University Team goes searching for evidence of what extra-terrestrial life might look like, he heads to Norris Geyser Basin in Yellowstone National Park. On Saturday the 24th of September Dr. Boyd was joined by the Webelos of Packs 524 and 552 of Livingston, Montana, with the goal of finding out what life might look like on another planet.

Dr. Boyd began the expedition by explaining some basic background on what Yellowstone is, how the Yellowstone area was formed, and some basic safety instructions on walking through a geothermal area as well as instructions on using the laser guns and pH strips he had brought for the Webolos. It was time to go 'Alien Hunting'.

The Scouts started their hunt at Echinus Geyser by first testing the temperature of the spring with their lasers. They were surprised to find that the temperature was between 156 and 166 degrees Fahrenheit; everybody agreed that it was way too hot for most life to survive. However the Scouts noted that the deep reds, oranges and faint greens associated with the spring seemed to indicate that life is present. At the outflow of the geyser the Scouts tested a sample of the spring water, sampled by Dr. Boyd, and found that it had a pH of between 3 and 4, a very acidic and extreme environment when compared to the boys drinking water which was pH 7.

The boys took their results to Dr. Boyd, who indicated that they were correct in believing that the spring was acidic, but that we should consider how life is thriving in such high temperature and acid conditions. Then Dr. Boyd shared with the boys why NASA scientists study geysers such at this: the iron-rich habitat at Echinus can be considered to be an Earth analog for what might be present on Mars since it is known that the red planet is rich in iron and has had hot springs in its distant past.
"The Boys learned how to look at a spring and based on visual observations, predict the pH and temperature of the spring as well as how the organisms were making a living. Such imaginative thinking is truly the cornerstone of NASA's astrobiology exploration program - in essence identifying patterns and using this to predict an outcome. Through iteration, such as what the Scouts experienced today in the Norris Geyser Basin, we refine our predictions and culminate in understanding" said Boyd. "The collective ideas that this group of youngsters generated about how life survives in extreme environments and the enthusiasm that the students had for NASA-supported science was impressive. I look forward to seeing how this group of young men progress through their Scout Program and their academic education."

The boys left the park with fond memories of red iron-eating bugs, black caldrons filled with mud, and pools of life that had found a way to survive in extreme environments. "What a wonderful opportunity Yellowstone National Park provides each of us to learn about the natural world that surrounds each and every one of us." said Boyd.

Source: NAI Newsletter

Join us for the next NAI Director's Seminar! Please RSVP if your site will be joining.

Date/Time: Monday, November 28, 2011 11:00AM Pacific

Presenter: John Peters (Montana State University)

Abstract: Iron-sulfur proteins are ubiquitous and catalyze a number of reactions important to metabolic energy transformations and carbon and nitrogen fixation. The similarities between iron-sulfur motifs within proteins and minerals are too strong to be coincidental and as such relating the properties of iron-sulfur minerals and iron-sulfur clusters in proteins is a powerful approach for understanding the transition form the nonliving to the living Earth and the emergence of biology. Our most recent work has revealed that complex cofactors in biology are synthesized in complicated metabolic pathways that have evolved stepwise. Individual steps in the biosynthetic pathways strongly are analogous to mechanisms responsible for tuning prebiotic mineral reactivity including "ligand accelerated catalysis" and "organic nesting". Insights into the origin and evolution of iron-sulfur enzymes and links to the RNA World will be presented.

For more information and participation instructions: http://astrobiology.nasa.gov/nai/seminars/detail/198

Source: NAI Newsletter