MSGID: 1:317/3 6406bdfd   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    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   
      
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   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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