College of Science News
Physicists explain origins of oxygen in atmosphere
New research by University of Texas at Arlington physicists sheds light on "The Great Oxidation of Earth's Atmosphere" or how oxygen developed. Understanding the development of oxygen is important for two reasons, according to Manfred Cuntz, associate professor of physics. First, understanding how the Earth's atmosphere attained its current oxygen level is crucial to understanding the origin and evolution of complex life forms. Second, knowing how oxygen developed in Earth's atmosphere will help scientists interpret the atmospheric chemistry signatures of other Earth-like planets and their potential for supporting alien life.
Cuntz, along with Physics Professor Zdzislaw Musielak and former graduate student Dipanjan Roy developed a theoretical model, published in the Nov. 20, 2009, issue of "The Astrophysical Journal Letters, " to explain the rise of oxygen that occurred about 2.4 billion years ago at a time when only very primitive life forms were able to exist.
Scientists think that the universe was created by the Big Bang almost 14 billion years ago, and its first gases were only hydrogen and helium. Early gases in Earth's atmosphere such as carbon dioxide and methane were supplied by volcanism. The level of life-supporting oxygen, created by photosynthesis, was less than one part in 100,000 of its present atmospheric level until about 2.4 billion years ago. It then jumped to about 1 percent of its present level, a 1,000-fold increase, and thereafter slowly rose to its current level.
There is a scientific debate over whether the increase occurred relatively smoothly or whether there were well-pronounced ups and downs, which scientists call "the yo-yo model." The results of the UT Arlington research clearly argue against the yo-yo model and favor a more steady increase of Earth's oxygen level.
Cuntz said the rise of the early Earth oxygen level involves a broad variety of aspects including atmospheric chemistry, geobiology and planetary science. Tools of study range from the analysis of mathematical differential equations, the focus of the work at UT Arlington, to considering analyses of ancient rocks. Stones are embedded with small pockets of gas, Cuntz said. The age of the rock, along with the gases embedded in it, provides a picture of what the atmosphere was like at that time.
This research is an example of the groundbreaking research UT Arlington professors and graduate students are engaged in as the University focuses on becoming a nationally-recognized Tier One institution.