View of earth and atmosphere, rising and falling oxygen levels
Twice in the Earth, the oxygen concentration in the atmosphere has increased rapidly. Details were still unclear about it. A new method now allows a look back - and proves baffling fluctuations of the vital connection. If you are interested in chrome ore buyers, you should have a look here
Great Oxidation Event geoscientists call the two events that have changed drastically from about 2.4 billion and 750 million years ago, the Earth's atmosphere. Suddenly rose respectively to the oxygen concentration - but the details of this for the emergence of life fundamentally important processes have so far not known.
Thanks to a new method, it is an international research team now managed to take a closer look at the history of the atmosphere. Robert Frei of the University of Copenhagen and his colleagues studied iron-rich sedimentary rocks from different places of the earth that is up to three billion years old. Frei's team analyzed the composition of the chrome isotopes in the rock and found that the oxygen isotopes reflect the content of the atmosphere.
The relationship, the researchers explain this: When the oxygen content increases the air reacts in the rock contained manganese to manganese oxide. This walk of electrons in the sediment adjacent to the chrome atoms of manganese. The way their electrons stripped atoms oxidize it easier to be dissolved in rain water and washed out. However, this happens when washing isotope chrome-53 were more likely than with chrome-52. The isotope ratio therefore allows conclusions about the oxygen content of air at the time, were included as the iron-bearing sediments of rock.
Surprising oxygen Delle
The analysis of samples from around the world brought a surprise, the researchers report in the journal Nature. Before 1.9 billion years, namely the oxygen levels dropped suddenly to values that were as low as before the first Great Oxidation Event. The level corresponding to a hundredth of the oxygen present in the atmosphere by around 21 percent. This, the researchers conclude that the first Great Oxidation Event triggered no gradual increase in oxygen concentration in the atmosphere.
Besides, the analysis also documented a direct relationship between high oxygen levels and a cooler climate. More oxygen made it possible for organisms, consume more CO2, "said Frei. As a result, it has become colder, because the concentration of the greenhouse gas fell. "We hope that the results help to understand the complex processes involved in climate change better."
