Tuesday, January 11, 2011

Oxygen Free Oceans Wrought Changes on Early Earth

by Joshua Hill

Geologists at the University of California, Riverside, have discovered chemical evidence that indicates Earth’s ancient oceans were not only oxygen-free, but also contained large quantities of hydrogen sulphide in some areas.

“We are the first to show that ample hydrogen sulfide in the ocean was possible this early in Earth’s history,” said Timothy Lyons, a professor of biogeochemistry and the senior investigator in the study, which appears in the February issue of Geology. “This surprising finding adds to growing evidence showing that ancient ocean chemistry was far more complex than previously imagined and likely influenced life’s evolution on Earth in unexpected ways – such as, by delaying the appearance and proliferation of some key groups of organisms.”

Hydrogen sulphide traditionally was believed to arise as a result of a process which saw oxygen weathering rocks, resulting in sulphate, which in turn was washed into the oceans where bacteria then convert the sulphate into hydrogen sulphide. Read More