Billions of years ago, the dense mat of cyanobacteria, the first life on earth, photosynthesis.. But scientists are still convinced why they triggered two transformative oxygenation events that transformed the Earth from a hypoxic planet into an oxygen-rich world where complex organisms could evolve and diversify. did not.
Researchers have now identified key factors that may have spurred the release of oxygen produced by microorganisms. It is the slowdown of the Earth’s rotation that began about 2.4 billion years ago. The Earth spins faster than it did on a newborn planet, completing turns in just a few hours, but slowly slowing over hundreds of millions of years. When the length of the day reaches a certain threshold (perhaps during these important oxygenation periods), the longer the sunlight, the more oxygen molecules are concentrated in the region (in the bacterial mat). May jump from to low concentration areas (atmosphere). , According to a new study.
Scientists have recently given clues to this link Sink hole Located at the bottom of Lake Huron. Lake Huron, adjacent to Michigan in the United States and Ontario in Canada, is one of the largest freshwater lakes in the world. The lake’s Middle Island sinkhole is 300 feet (91 meters) in diameter and about 80 feet (24 meters) below the surface. three, sulfur-Abundant water nourishes colorful microbes that breed in hypoxic environments, like the earliest forms of the planet. Bacteria did.
The chilly depths of the sinkhole are home to two types of microorganisms: purple cyanobacteria, which produce oxygen by photosynthesis and seek sunlight, and white bacteria, which consume sulfur and release sulfate. Microbes compete for position all day long, and sulfur-eating bacteria cover purple neighbors in the morning and evening, blocking access to the sun by the purple microbes. However, when the sunlight is strongest, white microbes can avoid the light and move deep into the sinkhole, leaving the purple cyanobacteria unobstructed, thereby photosynthesizing and releasing oxygen.
There may have been similar competition between microbial communities billions of years ago, and the exposure of oxygen-producing bacteria to sunlight was hampered by neighboring microbial communities, researchers wrote in a study. ing. Then, as the number of days on Earth increased, oxygen makers gained more time in the sun and released more oxygen into the atmosphere.
“I realized that there is a fundamental link between the dynamics of light and the release of oxygen, and that the link is based on the physics of molecular diffusion,” said the region of high concentration of molecules due to thermal changes. When moving from to low concentrations, the lead author of the study states. Judith Kratt, a research scientist at the Max Planck Institute for Marine Microbiology in Bremen, Germany.
“Even if the same amount of oxygen is produced in an hour, a shorter day means less oxygen escapes from the mat,” Kratt told Live Science in an email.
Today, the Earth completes a complete rotation around its axis once every 24 hours, but more than 4 billion years ago, researchers reported that the day lasted only about 6 hours.For billions of years, the earth’s continuous dance Month It slowed the rotation of the planet through a process known as tidal friction. As the Earth spins, the Moon (and, to a lesser extent, the Sun) attracts the Earth’s oceans. Research co-author Brian Albic, a professor of global environmental science at the University of Michigan’s Faculty of Letters, said the ocean would stretch and bulge from the center of the globe, drawing energy from spins and slowing it down. Science and art.
This slowdown is modest, but over the hundreds of millions of years, hours of additional sunlight have been added. Arbic emailed Live Science.
“Tidal friction continues to slow down the speed — days will continue to grow over geological time,” Arbic said.
Breath of fresh air
Researchers have modeled scenarios that alter the photoperiod and oxygen escape route from the microbial mat. When they compared the model with an analysis of competing microbial mats sampled from the Middle Island sinkhole, they found confirmation of their predictions: photosynthetic bacteria released more oxygen as the days went on. ..
This is not due to more photosynthesis by the microorganisms. Research co-author Arjun Chenne, a research scientist at the Leibniz Tropical Ocean Research Center in Bremen, said that the longer duration of sunlight meant that more oxygen escaped from the mat in a single day. Said the body.
“This subtle separation of oxygen release from sunlight is at the heart of the mechanism,” Chennu said in a statement.
The Earth’s atmosphere was formed after the planets were formed and cooled about 4.6 billion years ago, and was mostly composed of hydrogen sulfide, methane, and carbon dioxide (CO2). This is 200 times more CO2 than the current atmosphere.by Smithsonian Environmental Research Center..
Following the Great Oxidation Event (GOE) about 2.4 billion years ago and the Neoproterozoic Oxygenization event about 2 billion years later, everything has changed and atmospheric oxygen has reached levels of about 21% of what it is today. These two oxygenation events were previously associated with the activity of photosynthetic cyanobacteria, and this new evidence suggests that another factor may have been daytime on Earth. A microbial mat that acts “in parallel with other previously proposed propulsion of oxygenation,” said Kratt.
The findings were published in the journal on August 2nd. Nature Geoscience..
Originally published in Live Science.
The slowdown of the Earth’s rotation caused an oxygen surge
https://www.livescience.com/early-earth-rotation-increase-oxygen.html The slowdown of the Earth’s rotation caused an oxygen surge