American scientists from the University of Michigan in the course of a new study have found out how oxygen appeared in the Earth’s atmosphere. It turned out that this was due to a slowdown in the rotation of the planet.
It is known that the early Earth rotated very quickly, and a day on it lasted only a few hours. But over time, the rotation speed began to decrease due to the gravitational influence of the moon. Scientists conducted a study of the fossils, and the analysis showed that 1.4 billion years ago, a day lasted 18 hours, and 70 million years ago they were half an hour shorter than now. As a result, experts calculated that 1.8 milliseconds per century are added per day. Thus, a day in 100 years becomes longer by two milliseconds. And this has an impact on the biosphere.
The researchers drew attention to the bacteria that live in the Middle Island Gap, a natural underwater cavern on Lake Huron in North America. There is little oxygen and the water is saturated with sulfur. Moreover, these bacteria live there.
The researchers analyzed microbial mats found in Lake Huron. They are considered analogs of cyanobacteria, which caused the so-called oxygen catastrophe. By themselves, cyanobacterial mats are highly integrated prokaryotic communities, often linked by syntrophic relationships, which include photosynthetic cyanobacteria, facultative aerobes, and anaerobes.
During the study, biologists noticed that in the dark, sulfate reducers rise closer to the surface of the multilayer mat, and in light, they are replaced by photosynthetic cyanobacteria. However, the daily change of some bacteria to others does not occur instantly, taking several hours. It turns out that cyanobacteria do not have much time to “work”. And the longer the day, the more is left for the activation of the photosynthesis process and the production of oxygen.