Mineral particles and their role in oxygenating the Earth's atmosphere


Date:
March 6, 2023
Source:
University of Leeds
Summary:
Mineral particles played a key role in raising oxygen levels in the
Earth's atmosphere billions of years ago, with major implications
for the way intelligent life later evolved, according to new
research.


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FULL STORY ========================================================================== Mineral particles played a key role in raising oxygen levels in the
Earth's atmosphere billions of years ago, with major implications for
the way intelligent life later evolved, according to new research.


==========================================================================
Up to now, scientists have argued that oxygen levels rose as the result of photosynthesis by algae and plants in the sea, where oxygen was produced
as a by-product and released into the atmosphere.

But a research team at the University of Leeds say the photosynthesis
theory does not fully explain the increase in oxygen levels.

In a paper published today (Monday, March 6) in the journalNature
Geoscience, the researchers argue that when the algae and plants died,
they would have been consumed by microbes, a process that takes oxygen
from the atmosphere.

As a result, the amount of atmospheric oxygen was a balance between
what was produced through photosynthesis and what was lost as a result
of decomposition of the dead plant and algae.

To enable the atmospheric oxygen levels to get higher, the scientists
say the process of decay must have been slowed or halted. This happened
through what is known as mineral-organic carbon preservation, where
minerals in the oceans, particularly iron particles, bind onto the dead
algae and plants and inhibit their decay and decomposition.

The overall result is that oxygen levels were able to increase unhindered.

Caroline Peacock, Professor of Biogeochemistry in the School of Earth
and Environment at Leeds who led the research, said: "Scientists have
known for many years that mineral particles can bind with dead algae
and plants, making them less susceptible to attack by microbes and
shielding them from the decay process, but whether mineral particles
helped fuel the rise of atmospheric oxygen had never been tested."
The researchers set about testing their theory against known geological
events when levels of mineral particles were likely to have been higher,
for example, when the continents formed, resulting in a greater landmass
from which minerals -- including particles of iron -- would have blown
or been washed into the oceans.

For example, the Great Oxidation Event 2.4 billion years ago saw a spike
in oxygen levels in the atmosphere. This coincided with the gradual
formation of the continents, which would have caused a greater quantity
of mineral particles to flow into the oceans.

Dr Mingyu Zhao, formerly at Leeds but now at the Chinese Academy of
Sciences in Beijing, performed the study. He said: "The increase in
mineral particles in the oceans would have reduced the rate at which
algae was being decomposed.

This had a major impact on oxygen levels, allowing them to rise."
The increase in atmospheric oxygen had major ramifications for the
development of life. It resulted in the evolution of increasingly complex organisms, which moved from inhabiting water to living on land.

For Professor Peacock, the study not only brings greater understanding
to the way the Earth's atmosphere became oxygenated, it also gives a
glimpse of the conditions that are necessary for complex life to develop
on other planets.

She said: "Our investigation is providing a new understanding of how the Earth's atmosphere became oxygen rich, which eventually enabled complex
life forms to evolve.

"That is giving us an important insight into the conditions that need
to exist on other planets for intelligent life to develop.

"The existence of water on a planet is only part of the story. There
needs to be dry land to provide a source of mineral particles that will eventually end up in the oceans."
* RELATED_TOPICS
o Plants_&_Animals
# Marine_Biology # Extreme_Survival # Botany
o Earth_&_Climate
# Atmosphere # Geomagnetic_Storms # Oceanography
o Fossils_&_Ruins
# Origin_of_Life # Fossils # Charles_Darwin
* RELATED_TERMS
o Ozone o Earth's_atmosphere o Structure_of_the_Earth o
Timeline_of_evolution o Carbon_dioxide o Oxygen o Methane
o Earth

========================================================================== Story Source: Materials provided by University_of_Leeds. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Mingyu Zhao, Benjamin J. W. Mills, William B. Homoky, Caroline L.

Peacock. Oxygenation of the Earth aided by mineral-organic
carbon preservation. Nature Geoscience, 2023; DOI:
10.1038/s41561-023-01133-2 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/03/230306143427.htm

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