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Source: BBC News Online (via UASR)
Date: Sept 9, 1998
Scientists have been explaining how they have discovered a living example of how life may have first formed.
The site of their discovery is a hot spring more than 9,000ft under the Atlantic Ocean where a volcanic vent pours out hydrogen and provides conditions for the very earliest forms of life to thrive.
The experts say life may even now be springing into existence there now.
When life first appeared on earth 3.5 billion years ago the planet had no oxygen.
It has long been believed that hydrogen was the key then to unlocking the door of life.
The discovery of the hydrogen "black smoker" in the Rainbow hydrothermal field on the North Atlantic ridge has now provided the first concrete evidence to support the theory.
Microbes that feed on hydrogen have been found before in the hot water around hydrothermal vents, but never in a place with so much potential for life.
The Rainbow smoker, 3,500m deep and 200m wide, produces large quantities of the gas which is given off as a result of seawater reacting with rock dredged up from deep below the Earth's surface.
Major breakthrough
Scientists investigating the origins of life on Earth and possibly on other planets see the discovery as a major breakthrough.
Professor Joe Cann from the University of Leeds said: "Hydrogen has been a hot suspect for the origin of life and now we have a place in the modern world where life could originate and perhaps is originating now."
Life probably started with organic chemicals forming into amino acids, the basic components of living things, from which the first hydrogen-consuming microbes emerged.
But Prof Cann said any of these microbes being newly created around the Rainbow vent would instantly be snapped up by other higher forms of life that teem around black smokers.
Describing the findings for the first time at the British Association Festival of Science at Cardiff University, Prof Cann said: "The most primitive organisms on earth are hydrogen oxidising microbes.
"That's why we think life originated in a hot hydrogen environment. Now the discovery of this hydrogen-spewing black smoker makes the theory much more plausible."
It was a British scientist, Chris German, from the Southampton Oceanography Centre, who first spotted the plume of high temperature water that led scientists to the smoker.
A French submersible dived down and discovered the vent in the summer of last year.
Source: Carnegie Institute (via UASR)
Date: Sept 23, 1998
New high-pressure research by scientists at the Carnegie Institution 's Geophysical Laboratory, announced in this week's Nature magazine, reveals that unexpected chemical reactions occur in deep hydrothermal vents of the sea reactions that may have played a key role in the origin of life.
Jay Brandes, Bob Hazen, and their Geophysical Lab colleagues in Washington, D.C. report that one of the necessary first steps for life to begin the conversion of nitrogen to ammonia may have occurred readily in deep ocean vents. Nitrogen is an essential ingredient of amino acids and nucleic acids. But molecular nitrogen, N2, is relatively inert and unlikely to have given rise to the first vital signs of life. Most scientists believe instead that nitrogen in a more reduced, reactive form, i.e., ammonia, or NH3, was required. How did nitrogen, then, become ammonia?
Brandes and colleagues suggest that the most likely sites for ammonia production to occur were in the early Earth's crust and in hydrothermal vents, where iron-bearing minerals act as catalysts. The group conducted experiments investigating what happens when nitrogen, both as N2 and as its oxidized forms, NO2 and NO3 (all forms presumed to be present in the ancient oceans), react with iron oxides, iron sulphides, and basalt at high temperatures and pressures. Basalt is the predominant rock type at ocean ridge systems, and iron sulfides and oxides are ubiquitous in hydrothermal vents.
Using iron sulfides, they found that at 500C, up to 89% of the nitrogen converted to NH3 within 15 minutes! Iron oxide converted up to 46% of the nitrogen to ammonia, while powdered basalt converted up to 20% under these conditions. Reduction of N2, the largest reservoir of nitrogen on Earth, was slower but still resulted in up to 17% conversion to ammonia within 24 hours. The ammonia is stable, they found, to temperatures up to 800C, but only nitrogen gas survives temperatures above that temperature. Thus, N2 or its oxidized forms would have provided raw materials for an important and plentiful source of ammonia in the ancient oceans, perhaps providing oases of NH3 for the production of amino acids and nucleic acids in early life forms.
Brandes and coauthors point to two important conclusions, in addition to the unexpectedly high production of ammonia. The observation that ammonia does not survive at temperatures above 800C indicates that nitrogen on the Earth's surface would have been present only as nitrogen gas (N2) during the early phase of the Earth's development, when asteroid bombardments raised the surface temperature well above 800C. Thus, the ammonia necessary for the origins of life must have been generated after the initial formation of the Earth.
A second important conclusion of the work relates to a long-standing problem regarding the early atmosphere, known as the early faint-sun paradox. The radiation output of the Sun has increased gradually over the past several billion years. During the Earth's formation, the Sun 's radiant energy does not appear to have been sufficient to maintain liquid oceans unless, that is, a significant amount of a greenhouse gas was present to trap the Sun's energy and keep the planet warm. Ammonia is one of the most efficient greenhouse gases. If the oceans maintained a steady production of ammonia from hot vents, that ammonia would have also enriched the atmosphere through water-gas exchange at the ocean's surface, perhaps resolving the paradox.
Surprisingly, this research does little to settle an ongoing debate regarding the most probable site of life's origins. The prevailing paradigm for almost half a century has been that life began near the ocean's surface, bathed in sunlight. The rival hypothesis, that life arose near deep hydrothermal vents, is now being investigated at the Geophysical Laboratory and several other labs around the world. The present work demonstrates that high concentrations of ammonia might occur near vents, possibly making them sites for some interesting pre -life chemistry. But this ammonia will spread throughout the ocean and enter the atmosphere as well, thus providing a source of reduced nitrogen for almost any conceivable origin environment.
The Carnegie Institution, through its Geophysical Laboratory and Department of Terrestrial Magnetism co-located in upper northwestern Washington, D.C., is a member of NASA's new Astrobiology Institute, an effort to blend astronomy, biology, chemistry, and physics in the search to identify and understand the origins of life in the universe . NASA funded the research reported here.
The experiments were conducted at the Geophysical Laboratory using a technique developed years ago by Lab director emeritus Hatten S. Yoder, Jr. for the study of the origins of basalt. The nitrogen, water, and minerals are encapsulated in small gold containers and then subjected to high pressures and temperatures in Yoder's high -pressure apparatus. Capsules are opened and ammonia yields are determined by wet chemical techniques.
The Geophysical Lab, led by its new director, Wesley T. Huntress, Jr. (who arrives in October), is one of five departments of the Carnegie Institution of Washington, a nonprofit organization devoted to advanced research and education in the physical and biological sciences. The institution's president is the biologist Maxine F. Singer.
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