Aug. 16, 1999 MINNEAPOLIS / ST. PAUL -- Given enough heat and pressure, a naturally occurring iron-nickel alloy can produce methane that looks, for all practical purposes, as if it was produced from organic matter, according to work by researchers at the University of Minnesota and Oak Ridge National Laboratory. If the process, which the researchers conducted in the lab, should occur in Earth's crust, it could mean a source for methane other than digestion or decomposition of dead organic matter. The work is published in the Aug. 13 issue of Science.
The researchers call their process abiogenic--i.e., not connected with biological processes--methane formation. Most methane is thought to be produced when dead organic matter decays through the action of microbes or by heat-induced decomposition. Other means to produce methane in the laboratory exist, but Michael Berndt, a senior research associate in geology and geophysics at the University of Minnesota and coauthor of the Science paper, said he believes the newly discovered process could be an important means of generating methane in nature--specifically, under conditions of heat and pressure found deep in the Earth's oceanic crust.
"We're making no guesses as to the percentage of methane that may come from this source," said Berndt. "But our study shows that some methane thought to have been produced by bacteria may actually have been produced abiogenically."
Developed by Berndt and Juske Horita of the chemical and analytical sciences division of Oak Ridge National Laboratory, the new process produces methane from bicarbonate ions and hydrogen at temperatures up to 400 degrees C. The catalyst for the conversion was an iron-nickel alloy found in certain parts of the oceanic crust. Berndt said the methane produced was chemically difficult to distinguish from organically produced methane.
As for its significance, he said he would leave that to other scientists.
"Knowing where methane comes from puts us in a better position to find it," he said. "The one thing for sure is that methane can no longer be assumed to come solely from organic decay."
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