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Oxygen formation in Earth water

  1. Oct 14, 2016 #1
    I always wondered why they say water and photons created the first microbes which later evolved and produced oxygen which filled our oceans and atmosphere. So how could have water existed without oxygen? I tried to look up and came up with different explanations, but it doesn't make sense.
     
  2. jcsd
  3. Oct 14, 2016 #2

    Evo

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    You need to read about stromatolites.

    from the link below

    Bacteria, including the photosynthetic cyanobacteria, were the only form of life on Earth for the first 2 billion years that life existed on Earth. Stromatolites are layered mounds, columns, and sheet-like sedimentary rocks. They were originally formed by the growth of layer upon layer of cyanobacteria, a single-celled photosynthesizing microbe that lives today in a wide range of environments ranging from the shallow shelf to lakes, rivers, and even soils. Cyanobacteria are prokaryotic cells (the simplest form of modern carbon-based life) in that they lack a DNA-packaging nucleus.

    Although simple, cyanobacteria were ultimately responsible for one of the most important "global changes" that the Earth has undergone. Being photosynthetic, cyanobacteria produce oxygen as a by-product. Photosynthesis is the only major source of free oxygen gas in the atmosphere. As stromatolites became more common 2.5 billion years ago, they gradually changed the Earth's atmosphere from a carbon dioxide-rich mixture to the present-day oxygen-rich atmosphere. This major change paved the way for the next evolutionary step, the appearance of life based on the eukaryotic cell (cell with a nucleus).

    http://www.indiana.edu/~geol105b/images/gaia_chapter_10/stromatolites.htm
     
    Last edited: Oct 14, 2016
  4. Oct 15, 2016 #3
    Totally agree with that. But they needed water to survive. Hence H2O, then how? o.o
    idk if im wrong here..
     
  5. Oct 15, 2016 #4

    Evo

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    That appears to be something that is unknown, there are some theories. I will do more searching for you later today, I was unable to come up with much earlier, just the usual theories, comets, asteroids... That may be the best we have at this time.

    http://www.livescience.com/33391-where-did-water-come-from.html
     
  6. Oct 15, 2016 #5

    davenn

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    I think you will find that the microbes just added the oxygen content to the atmosphere as stated in that link @Evo gave.
    There's no reason to suggest that the microbes existed BEFORE the oceans, which is what you are suggesting

    So do you have any links to back up your "they say" claim ?


    Dave
     
  7. Oct 15, 2016 #6
    Thanks.. :)
     
  8. Oct 15, 2016 #7
    Hi sup? I don't really remember. I watched some documentaries and googled up some stuffs. I'll try to look for that and send it to you.
     
  9. Oct 15, 2016 #8

    davenn

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    no prob's :smile:

    it's just a really good idea to give links (reliable ones) to claims
    you will find that "they say" doesn't really cut the mustard on the forum


    and btw ... welcome to PF


    Dave
     
    Last edited by a moderator: Oct 15, 2016
  10. Oct 15, 2016 #9
    th
    thanks bro
     
  11. Oct 15, 2016 #10
    The role of stromatolites in the oxygenation of earth is a "yes, but..." story. I have a couple hundred papers that show the complexity of the problem. I was, and am, more concerned with astrobiology and the origin of life and my experience in molecular paleontology is with a Jurassic and younger earth. I'll post a few of the papers now. The first has a nice chart showing some major biogeochemical changes in the early earth. Significant is that there is a huge burst in C-13 associated with stromatolites.

    Global Biogeochemical Changes at Both Ends of the Proterozoic: Insights from Phosphorites
    ASTROBIOLOGY Volume 10, Number 2, 2010 a Mary Ann Liebert, Inc. DOI: 10.1089=ast.2009.0360

    Availability of O2 and H2O2 on Pre-Photosynthetic Earth
    ASTROBIOLOGY Volume 11, Number 4, 2011 a Mary Ann Liebert, Inc. DOI: 10.1089/ast.2010.0572

    Stromatolites in the *3400 Ma Strelley Pool Formation, Western Australia: Examining Biogenicity
    from the Macro- to the Nano-Scale
    ASTROBIOLOGY Volume 10, Number 4, 2010 a Mary Ann Liebert, Inc. DOI: 10.1089=ast.2009.0423

    The case for a Neoproterozoic Oxygenation Event: Geochemical evidence and biological consequences
    http://www.geosociety.org/gsatoday/archive/21/3/article/i105

    The Proterozoic Record of Eukaryotes
    http://paleobiol.geoscienceworld.or...fb61c21509908b70a1215f50&keytype2=tf_ipsecsha

    Tropical laterites, life on land, and the history of atmospheric oxygen in the Paleoproterozoic
    http://geology.gsapubs.org/content/30/6/491.full.pdf

    Were kinetics of Archean calcium carbonate precipitation related to oxygen concentration?
    http://geology.gsapubs.org/content/24/2/119.full.pdf+html

    Oxygen in the Precambrian atmosphere: An evaluation of the geological evidence
    http://geology.gsapubs.org/content/10/3/141.full.pdf+html

    This is a decent start, I think.




     
  12. Oct 15, 2016 #11
    https://arxiv.org/pdf/1011.2710v1.pdf
    Formation of early water oceans on rocky planets

    Lindy E-T, the author of that paper, showed that enough water could be carried in the primordial dust and survived the accretionary phases such that the earth had enough water in its earliest stages to account for the water that is now here. Asteroids, meteorites and comets aren't needed to account for the original ocean volume.
    Occam's origin of the Moon Nature Geoscience 6, 996–998 (2013) doi:10.1038/ngeo2026
    "Following almost three decades of some certainty over how the Moon was formed, new geochemical measurements have thrown the planetary science community back into doubt. We are either modelling the wrong process, or modelling the process wrong." Should ()new theories of the moon's origin become a new thread, I'll post some links.

    I put there for the cautionary advice that applies to all systems modelling, especially when many proxies are used in place of the reaL deal.
     
  13. Oct 15, 2016 #12

    jim mcnamara

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    @CapnGranite
    Astrobiology seems to behind a paywall, specifically the first article: DOI: 10.1089=ast.2009.0360
    Since there are several of these, $US 51.00 for each one. Geosociety.org papers - same thing.

    @D H - are there any open access "seminal" papers on oxygenation of the Early atmosphere, that are comparable? I am assuming you can see these.
     
  14. Oct 15, 2016 #13

    Evo

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    I think what cookiemonster is asking is simply "where did the first water on earth come from? Perhaps we should just stick with that question. :smile: @CapnGranite I think a couple of papers you attempted to link might have more detail than the article I linked.
     
  15. Oct 15, 2016 #14
    http://news.nationalgeographic.com/news/2014/10/141030-starstruck-earth-water-origin-vesta-science/
    Mystery of Earth's Water Origin Solved
    Instead of arriving later by comet impact, Earth's waters have likely existed since our planet's birth.
    "The study shows that Earth's water most likely accreted at the same time as the rock," said Marschall.

    This is the only unlocked paper/article I have on the computer.

    While this isn't open-access, Science magazine is in many libraries. This is one of the most recent papers on the origin of the earth's water.
    http://science.sciencemag.org/content/sci/346/6209/623.full.pdf
    Early accretion of water in the inner solar system from a carbonaceous chondrite–like source
    ABSTRACT:
    Determining the origin of water and the timing of its accretion within the inner solar system is important for understanding the dynamics of planet formation. The timing of water accretion to the inner solar system also has implications for how and when life emerged on Earth. We report in situ measurements of the hydrogen isotopic composition of the mineral apatite in eucrite meteorites, whose parent body is the main-belt asteroid 4 Vesta. These measurements sample one of the oldest hydrogen reservoirs in the solar system and show that Vesta contains the same hydrogen isotopic composition as that of carbonaceous chondrites. Taking into account the old ages of eucrite meteorites and their similarity to Earth’s isotopic ratios of hydrogen, carbon, and nitrogen, we demonstrate that these volatiles could have been added early to Earth, rather than gained during a late accretion event.
    "Our findings cannot preclude a late addition of water for Earth with a carbonaceous chondrite–like D/H, but the observation indicates that a late addition of water is not necessary"
     
  16. Oct 15, 2016 #15

    Evo

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    Thank you. I think this probably won't satisfy CookieMonster's question of how water could have formed (H2O) if there was no oxygen present to create the water. Was there oxygen present when the earth formed and the water was created or was that not necessary, this is where it really gets out of my realm of armchair reading.

    I know one of you knows the answer.
     
  17. Oct 15, 2016 #16
    The water existed as ice before the earth was formed.

    http://www.cosmos.esa.int/documents...oloS.pdf/6e43745b-f365-4c8c-811c-e679c5fd1a54
    Interstellar Water Ice Formation: A laboratory perspective

    That was in
    http://www.cosmos.esa.int/web/herschel/water-in-the-universe-from-clouds-to-oceans
    WATER IN THE UNIVERSE: FROM CLOUDS TO OCEANS
    The conference covered all astrophysical aspects of water, including the water trail, from the formation of water in molecular clouds to water on planetary bodies, including in our own solar system; water as a probe of physics and and chemistry; and water in nearby to water in extragalactic and high redshift sources.


     
  18. Oct 18, 2016 #17
    Sorry, I can't make any sense of this. Do I understand that the question is why/how oxygen atoms were originally present on Earth as it emerged from the condensing solar system cloud?

    Of course there were oxygen atoms (almost all of them chemically combined of course), lots and lots of them. Our parent supernova(e) plus its parent sun(s) produced elements eventually up to the transuranics, including Pm and Tc, though not all of them in the same concentrations and not all of them lasting long. Oxygen, Si, and Fe were among the commonest (surprise) and in the eventual settling out of various substances, Si and O wound up in the crust in huge proportions. However, there also were fair amounts of H, S, Li, Na, C and the whole alphabet soup, enough that only traces of free O2 or O3 ever existed, and that transiently when it did. But water was fairly plentiful and so were various other hydroxides and hydroxyl compounds. We call such things oceans, right?

    The problem was not where the O atoms (in compounds) came from; they were there. The problem was where the free oxygen came from, because O2 is so reactive. That was where photosynthesis came in, and after it had been going for a while, given the plentiful quantities of CO2 and H2O to work on, we wound up with lots of O2.

    So OK, I'm stupid; what's the mystery?
     
  19. Oct 18, 2016 #18
    It might help to add, that if we look at any sort of chemical mess in a mud-and-rock ball such as early Earth, with all sorts of compounds being mixed up in heat and cold and radiation and what not (no life yet!) the range of reactions that we might expect, and the mutual co-precipitations and crystallisations would ensure that all sorts of compounds would form, change and re-form, always favouring the most stable forms under reigning conditions and equilibria. Hence plenty of H2O, NH3, CO2, SiO2 and so on.

    Right?
     
  20. Oct 18, 2016 #19
    This explanation about life force generating free oxygen ignores the fact that more than 90% of the CO2 on our planet is locked up in rocks by nonliving force. All that locked up CO2 was in the atmosphere early on in Earth's history. The rocks have the truth and it has not yet been discovered by science so a little humility, please.
     
  21. Oct 18, 2016 #20
    Depending on the redox conditions as the earth was in that early stage of differentiation and degassing, chemical species were forming and disappearing. Jon Richfield has is correct, as I see it, but it was a bit more complex. I'm not so sure that O2 increases in the atmosphere came from the rise of bacteria alone. After the initial, and probable high S and CO2 period, there is evidence that degassing and reactions shifted that environment to one favorable for stable O2. At the same time, stromatolites and free-floating bacteria added to the atmospheric oxygen.
    There is a a lack of humility in saying " All that locked up CO2 was in the atmosphere early on in Earth's history."
     
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