https://reasonandscience.catsboard.com/t1556-the-earth-s-atmosphere
ASTRONOMICAL ORIGINS OF LIFE Steps Towards Panspermia Edited by F. HOYLE and N.e. WICKRAMASINGHE page 105
The oldest surviving rocks have oxidation states that are indicative of an oxidising rather than a reducing atmosphere, at any rate at the time when the rocks condensed.
The oxidation state of Hadean magmas and implications for early Earth’s atmosphere
1 DECEMBER 2011
Selected Hadean zircons (having chemical characteristics consistent with crystallization specifically from mantle-derived melts) suggest oxygen fugacities similar to those of Archaean and present-day mantle-derived lavas as early as ~4,350 Myr before present. These results suggest that outgassing of Earth’s interior later than ~200 Myr into the history of Solar System formation would not have resulted in a reducing atmosphere.
http://sci-hub.ren/https://www.nature.com/articles/nature10655
Leslie Orgel wrote:
Recent investigations indicate the earth's atmosphere was never as reducing as Urey and Miller presumed. 7
Precambrian atmospheric oxygen: evidence in the sedimentary distributions of carbon, sulfur, uranium, and iron
12 April 1976
In general, we find no evidence in the sedimentary distributions of carbon, sulfur, uranium, or iron, that an oxygen-free atmosphere has existed at any time during the span of geological history recorded in well preserved sedimentary rocks. 8
‘the sedimentary distributions of carbon, sulfur, uranium, and ferric and ferrous iron depend greatly upon ambient oxygen pressure and should reflect any major change in proportion of oxygen in the atmosphere or hydrosphere. The similar distributions of these elements in sedimentary rocks of all ages are here interpreted to indicate the existence of a Precambrian atmosphere containing much oxygen.’
‘we know of no evidence which proves orders-of-magnitude differences between Middle Archaean and subsequent atmospheric compositions, hydrospheric compositions, or total biomasses.’
A non-hostile climate was prerequisite for the evolution of life as we know it. Was there liquid water? Was there crust on which life could take hold? Earth’s habitable surface today is certainly different than it was 4.6 Bya when it first condensed out of our Sun’s dusty, rotating nebula. We have very little remaining evidence of Earth’s crust during its first 500 million years — just a handful of hardy zircon grains from the Jack Hills conglomerate in western Australia. Despite their tiny size, locked within each zircon’s crystal lattice is a remarkable record of events back 4.4 Bya. Their chemistry, detected by ion beams just a few microns wide, suggest they formed as part of buoyant crust and in the presence of liquid water. 9
![atmosphere - The earth's atmosphere JvPeuYx](https://i.imgur.com/JvPeuYx.png)
We live in a unique environment. Earth is the only planet we know of that has an oxygen-rich atmosphere, as well as a hydrosphere, and both oceanic and continental crust, which combine to sustain complex life 4
The assumption of an oxygen-free atmosphere has also been rejected on theoretical grounds. The ozone layer around planet earth consists of a thin but critical blanket of oxygen gas in the upper atmosphere. This layer of oxygen gas blocks deadly levels of ultraviolet radiation from the sun. Without oxygen in the early atmosphere, there could have been no ozone layer over that early earth. Without an ozone layer, all life on the surface of planet earth would face certain death from exposure to intense ultraviolet radiation. Furthermore, the chemical building blocks of proteins, RNA and DNA, would be quickly annihilated because ultraviolet radiation destroys their chemical bonds. It doesn't matter if these newly formed building blocks are in the atmosphere, on dry ground, or under water. 1
So we have a major dilemma. The products of the Miller-Urey experiments would be destroyed if oxygen was present, and they would be destroyed if it wasn't! This "catch 22" has been noted by evolutionist and molecular biologist Michael Denton:
"What we have then is a sort of 'Catch 22' situation. If we have oxygen we have no organic compounds, but if we don't we have none either."
Even if the building blocks of life could survive the effects of intense ultraviolet radiation and form life spontaneously, the survival of any subsequent life forms would be very doubtful in the presence of such heavy ultraviolet light. Ozone must be present to protect any surface life from the deadly effects of ultraviolet radiation from the sun.
The Earth’s Atmospheric Conditions Are Favorable to Life:
The surface gravity of Earth is critical to its ability to retain an atmosphere friendly to life. If Earth’s gravity were stronger, our atmosphere would contain too much methane and ammonia. If our planet’s gravity were weaker, Earth wouldn’t be able to retain enough water. As it is, Earth’s atmosphere has a finely calibrated ratio of oxygen to nitrogen—just enough carbon dioxide and adequate water vapor levels to promote advanced life, allow photosynthesis (without an excessive greenhouse effect), and to allow for sufficient rainfall. 2
Our atmosphere contains the right proportions of gases that are absolutely essential for life. Some of those gases, by themselves, are deadly. But because air contains safe proportions of these gases, we can breathe them without harm.
Visible light is also incredibly fine-tuned for life to exist Though visible light is only a tiny fraction of the total electromagnetic spectrum coming from the sun, it happens to be the "most permitted" portion of the sun's spectrum allowed to filter through the our atmosphere. All the other bands of electromagnetic radiation, directly surrounding visible light, happen to be harmful to organic molecules, and are almost completely absorbed by the atmosphere. The tiny amount of harmful UV radiation, which is not visible light, allowed to filter through the atmosphere is needed to keep various populations of single cell bacteria from over-populating the world (Ross; reasons.org). The size of light's wavelengths and the constraints on the size allowable for the protein molecules of organic life, also seem to be tailor-made for each other. This "tailor-made fit" allows photosynthesis, the miracle of sight, and many other things that are necessary for human life. These specific frequencies of light (that enable plants to manufacture food and astronomers to observe the cosmos) represent less than 1 trillionth of a trillionth (10^-24) of the universe's entire range of electromagnetic emissions. Like water, visible light also appears to be of optimal biological utility (Denton; Nature's Destiny).
Distance of the earth from the sun : Malcolm Bowden says, "If it were 5% closer, then the water would boil up from the oceans and if it were just 1% farther away, then the oceans would freeze, and that gives you just some idea of the knife edge we are on."
The carbon dioxide level in atmosphere If greater: runaway greenhouse effect would develop. If less: plants would be unable to maintain efficient photosynthesis
Oxygen quantity in atmosphere If greater: plants and hydrocarbons would burn up too easily. If less: advanced animals would have too little to breathe
Nitrogen quantity in atmosphere If greater: too much buffering of oxygen for advanced animal respiration; too much nitrogen fixation for support of diverse plant species.
If less: too little buffering of oxygen for advanced animal respiration; too little nitrogen fixation for support of diverse plant species.
Atmospheric pressure: If too small: liquid water will evaporate too easily and condense too infrequently; weather and climate variation would be too extreme; lungs will not function. If too large: liquid water will not evaporate easily enough for land life; insufficient sunlight reaches planetary surface; insufficient uv radiation reaches planetary surface; insufficient climate and weather variation; lungs will not function
Atmospheric transparency:If smaller: insufficient range of wavelengths of solar radiation reaches the planetary surface. If greater: too broad a range of wavelengths of solar radiation reaches planetary surface
stratospheric ozone quantity:If smaller: too much uv radiation reaches planet’s surface causing skin cancers and reduced plant growth . If larger: too little uv radiation reaches planet’s surface causing reduced plant growth and insufficient vitamin production for animals
The Oxygen Problem
http://xwalk.ca/origin.html
The atmospheric conditions proposed by Oparin, Haldane and Urey were radically different from what presently exists. Because oxygen destroys the chemical building blocks of life, they speculated that the early earth had an oxygen-free atmosphere.
However, in the last twenty years, evidence has surfaced that has convinced most atmospheric scientists that the early atmosphere contained abundant oxygen.
In the 1970's Apollo 16 astronauts discovered that water is broken down into oxygen and hydrogen gas in the upper atmosphere when it is bombarded by ultraviolet radiation. This process, called photo dissociation, is an efficient process which would have resulted in the production of large quantities of oxygen in a relatively short time. Studies by the astronauts revealed that this process is probably a major source of oxygen in our current atmosphere. 2 H2O + uv Radiation -- H2 (hydrogen gas) + O2 (oxygen gas)
The assumption of an oxygen-free atmosphere has also been rejected on theoretical grounds. The ozone layer around planet earth consists of a thin but critical blanket of oxygen gas in the upper atmosphere. This layer of oxygen gas blocks deadly levels of ultraviolet radiation from the sun.9 Without oxygen in the early atmosphere, there could have been no ozone layer over that early earth. Without an ozone layer, all life on the surface of planet earth would face certain death from exposure to intense ultraviolet radiation. Furthermore, the chemical building blocks of proteins, RNA and DNA, would be quickly annihilated because ultraviolet radiation destroys their chemical bonds.10 It doesn't matter if these newly formed building blocks are in the atmosphere, on dry ground, or under water.11,12,13
So we have a major dilemma. The products of the Miller-Urey experiments would be destroyed if oxygen was present, and they would be destroyed if it wasn't! This "catch 22" has been noted by evolutionist and molecular biologist Michael Denton:
"What we have then is a sort of 'Catch 22' situation. If we have oxygen we have no organic compounds, but if we don't we have none either."
Even if the building blocks of life could survive the effects of intense ultraviolet radiation and form life spontaneously, the survival of any subsequent life forms would be very doubtful in the presence of such heavy ultraviolet light. Ozone must be present to protect any surface life from the deadly effects of ultraviolet radiation from the sun.
Finally, the assumption that there was no oxygen in the early atmosphere is not borne out by the geologic evidence. Geologists have discovered evidence of abundant oxygen content in the oldest known rocks on earth.
Again, Michael Denton:
"Ominously, for believers in the traditional organic soup scenario, there is no clear geochemical evidence to exclude the possibility that oxygen was present in the Earth's atmosphere soon after the formation of its crust."
All of this evidence supports the fact that there was abundant oxygen on the early earth.
Ammonia and Methane Short Lived
The assumption of an atmosphere consisting mainly of ammonia, methane, and hydrogen, has also been seriously questioned. In the 1970's scientists concluded that ultraviolet radiation from the sun, as well as simple "rainout," would eliminate ammonia and methane from the upper atmosphere in a very short time.16 In 1981, Atmospheric scientists from NASA concluded that:
"the methane and ammonia-dominated atmosphere would have been very short lived if it ever existed at all."
http://bio-complexity.org/ojs/index.php/main/article/view/BIO-C.2013.1/BIO-C.2013.1
if atmospheric levels of oxygen rise much above 21%, spontaneous combustion of carbon compounds becomes an increasing danger [22: p. 34]. The fact that oxygen levels sufficient to support high levels of metabolism by air-breathing organisms do not at the same time support spontaneous conflagrations is clearly a coincidence of great relevance for terrestrial life.
http://adsabs.harvard.edu/abs/2004NCimC..27...99F
The details on the origin of nitrogen, which exists so abundantly in the Earth's atmosphere, are missing.
http://www.bestbiblescience.org/ol1.htm
Our current atmosphere consists primarily of oxygen (21%) and nitrogen (78%) and is called oxidizing because of chemical reactions produced by oxygen. For example, iron is oxidized to form iron oxide or rust.
The presence of oxygen in a hypothetical primordial atmosphere poses a difficult problem for notions of self-assembling molecules. If oxygen is present, there would be no amino acids, sugars, purines, etc. Amino acids and sugars react with oxygen to form carbon dioxide (CO2) and water.
Because it is impossible for life to evolve with oxygen, evolutionists theorize an early atmosphere without oxygen. This departs from the usual evolutionary theorizing where a uniformistic view is held (i.e. where processes remain constant over vast stretches of time). In this case the present is NOT the key to the past.
Instead, they propose a "reducing" (called thus because of the chemical reactions) atmosphere which contains free hydrogen. Originally, they postulated an atmosphere consisting of carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), ammonia (NH3), free hydrogen and water vapor. Newer schemes exclude ammonia and methane.
There is a problem if you consider the ozone (O3) layer which protects the earth from ultraviolet rays. Without this layer, organic molecules would be broken down and life would soon be eliminated. But if you have oxygen, it prevents life from starting. A "catch-22" situation (Denton 1985, 261-262):
Atmosphere with oxygen => No amino acids => No life possible!
Atmosphere without oxygen => No ozone => No life possible!
In must be noted at this point that the existence of a reducing atmosphere is theoretical and does not rely on physical evidence. To the contrary, there are geological evidence for the existence of an oxidizing atmosphere as far back as can be determined. Among these are the precipitation of limestone (calcium carbonate) in great quantities, the oxidation of ferrous iron in early rocks (Gish 1972, 8)and the distribution of minerals in early sedimentary rocks (Gish 1984T).
http://www.livescience.com/39938-earth-had-oxygen-earlier.html
Oxygen may have filled Earth's atmosphere hundreds of millions of years earlier than previously thought, suggesting that sunlight-dependent life akin to modern plants evolved very early in Earth's history, a new study finds.
The findings, detailed in the Sept. 26 issue of the journal Nature, have implications for extraterrestrial life as well, hinting that oxygen-generating life could arise very early in a planet's history and potentially suggest even more worlds could be inhabited around the universe than previously thought, the study's authors said.
It was once widely assumed that oxygen levels remained low in the atmosphere for about the first 2 billion years of Earth's 4.5-billion-year history. Scientists thought the first time oxygen suffused the atmosphere for any major length of time was about 2.3 billion years ago in what is called the Great Oxidation Event. This jump in oxygen levels was almost certainly due to cyanobacteria — microbes that, like plants, photosynthesize and exhale oxygen.
However, recent research examining ancient rock deposits had suggested that oxygen may have transiently existed in the atmosphere 2.6 billion to 2.7 billion years ago.
The new study pushes this boundary back even further, suggesting Earth's atmosphere became oxygenated about 3 billion years ago, more than 600 million years before the Great Oxidation Event. In turn, this suggests that something was around on the planet to put that oxygen in the atmosphere at this time.
"The fact oxygen is there requires oxygenic photosynthesis, a very complex metabolic pathway, very early in Earth's history," said researcher Sean Crowe, a biogeochemist at the University of British Columbia in Vancouver. "That tells us it doesn't take long for biology to evolve very complex metabolic capabilities." [7 Theories on the Origin of Life]
Ancient oxygen reactions
Crowe and his colleagues analyzed levels of chromium and other metals in samples from South Africa that could serve as markers of reactions between atmospheric oxygen and minerals in Earth's rocks. They looked at both samples of ancient soil and marine sediments from about the same time period — 3 billion years ago.
The researchers focused on the different levels of chromium isotopes within their samples. Isotopes are variants of elements; all isotopes of an element have the same number of protons in their atoms, but each has a different number of neutrons — for instance, each atom of chromium-52 has 28 neutrons, while atoms of chromium-53 have 29.
When atmospheric oxygen reacts with rock — a process known as weathering —heavier chromium isotopes, such as chromium-53, often get washed out to sea by rivers. This means heavier chromium isotopes are often depleted from soils on land and enriched in sediments in the ocean when oxygen is around. These proportions of heavier chromium were just what were seen in the South African samples. Similar results were seen with other metals, such as uranium and iron, that hint at the presence of oxygen in the atmosphere.
"We now have the chemical tools to detect trace atmospheric gases billions of years ago," Crowe told LiveScience.
'Almost certainly biological'
All in all, the researchers suggest atmospheric oxygen levels 3 billion years ago were about 100,000 times higher than what can be explained by regular chemical reactions in Earth's atmosphere. "That suggests the source of this oxygen was almost certainly biological," Crowe said.
"It's exciting that it took a relatively short time for oxygenic photosynthesis to evolve on Earth," Crowe added. "It means that it could happen on other planets on Earth, expanding the number of worlds that could've developed oxygenated atmospheres and complex oxygen-breathing life."
Future research can look for similarly aged rocks from other places, both on and outside Earth, to confirm these findings. "Research could also look at earlier rocks," Crowe said. "Chances are, if there was oxygen 3 billion years ago, there was likely oxygen production sometime before as well. How far back does it go?"
http://www.scientificamerican.com/article/origin-of-oxygen-in-atmosphere/
"What it looks like is that oxygen was first produced somewhere around 2.7 billion to 2.8 billion years ago. It took up residence in atmosphere around 2.45 billion years ago," says geochemist Dick Holland, a visiting scholar at the University of Pennsylvania. "It looks as if there's a significant time interval between the appearance of oxygen-producing organisms and the actual oxygenation of the atmosphere."
So a date and a culprit can be fixed for what scientists refer to as the Great Oxidation Event, but mysteries remain. What occurred 2.45 billion years ago that enabled cyanobacteria to take over? What were oxygen levels at that time? Why did it take another one billion years—dubbed the "boring billion" by scientists—for oxygen levels to rise high enough to enable the evolution of animals?
Most important, how did the amount of atmospheric oxygen reach its present level? "It's not that easy why it should balance at 21 percent rather than 10 or 40 percent," notes geoscientist James Kasting of Pennsylvania State University. "We don't understand the modern oxygen control system that well."
http://www.dailytech.com/Scientists+Show+Evidence+of+How+Earth+Got+Its+Oxygen/article31853.htm
Researchers even have a good idea of where algae got their photosynthesis genes. Describes geobiology Professor Woodward Fischer of the California Institute of Technology (CalTech), "Water-oxidizing or water-splitting photosynthesis was invented by cyanobacteria approximately 2.4 billion years ago and then borrowed by other groups of organisms thereafter. Algae borrowed this photosynthetic system from cyanobacteria, and plants are just a group of algae that took photosynthesis on land, so we think with this finding we're looking at the inception of the molecular machinery that would give rise to oxygen."
http://www.reasonablefaith.org/the-teleological-argument-and-the-anthropic-principle
For example, CO2 has the property, unique among gases, of having at ordinary temperatures about the same concentration of molecules per unit volume in water as in air. This enables CO2 to undergo perpetual exchange between living organisms and their environment so that it is everywhere available for photosynthesis and thereby for molecular synthesis. The element N, on the other hand, is a rare element on Earth, but it does makeup 80% of the earth's atmosphere, which is a unique stroke of fortune for Earth's living organisms.
The reason for the abundance of oxygen in the atmosphere is the presence of a very large number of organisms which produce oxygen as a byproduct of their metabolism.// that's exactly right. These organisms are called cyanobacteria. And their capabilities are nothing more than astounding. They are one of the oldest bacteria that live on earth, estimates in scientific literature are 3 to 3,5 billion years. No cyanobacteria, no oxygen, no higher life forms. These cyanobacteria have incredibly sophisticated enzyme proteins and metabolic pathways, like the electron transport chains in photosynthesis, ATP synthase motors, circadian clock, the photosynthetic light reactions, carbon concentration mechanism, and transcriptional regulation, they produce binded nitrogen through nitrogenase, a highly sophisticated mechanism to bind nitrogen, used as a nutrient for plant and animal growth. The Nitrogen cycle is a lot more complex than the carbon cycle. Nitrogen is a very important element. It makes up almost 80% of our atmosphere, and it is an important component of proteins and DNA, both of which are the building blocks of animals and plants. Therefore without nitrogen, we would lose one of the most important elements on this planet, along with oxygen, hydrogen, and carbon. There are a number of stages to the nitrogen cycle, which involve breaking down and building up nitrogen and it’s various compounds.There is no real starting point for the nitrogen cycle. It is an endless cycle.Potential gaps in the system cannot be reasonably bypassed by inorganic nature alone.It must have a degree of specificity that in all probability could not have been produced by chance. A given function or step in the system may be found in several different unrelated organisms. The removal of any one of the individual biological steps will resort in the loss of function of the system. The data suggest that the nitrogen cycle may be irreducibly interdependent based on the above criteria. No proposed neo-Darwinian mechanisms can explain the origin of such a system.Without cyanobacteria - no fixed nitrogen is available.Without fixed nitrogen, no DNA, no amino-acids, no protein can be synthesized.Without DNA, no amino-acids, protein, or cyanobacteria are possible. So that's an interdependent system.
New study: Oxygenic photosynthesis goes back three billion years
http://www.uncommondescent.com/intelligent-design/new-study-oxygenic-photosynthesis-goes-back-three-billion-years/
An international team of scientists has published an article in Nature magazine, suggesting that oxygen began accumulating in the atmosphere at least three billion years ago. The team’s findings raise a troubling question for Darwinian evolutionists: how did the exquisitely complex metabolism of oxygenic photosynthesis arise so soon after the dawn of life?
An oxygen concentration of 0.03% might not sound like much, but it’s at least 10 times higher than most scientists had previously expected. As the Nature article explains, the new finding radically revises the old picture:
It is widely assumed that atmospheric oxygen concentrations remained persistently low (less than 10^−5 [0.00001] times present levels) for about the first 2 billion years of Earth’s history. The first long-term oxygenation of the atmosphere is thought to have taken place around 2.3 billion years ago, during the Great Oxidation Event. Geochemical indications of transient atmospheric oxygenation, however, date back to 2.6–2.7 billion years ago… Overall, our findings suggest that there were appreciable levels of atmospheric oxygen about 3 billion years ago, more than 600 million years before the Great Oxidation Event and some 300–400 million years earlier than previous indications for Earth surface oxygenation. (Square brackets mine – VJT.)
When did oxygenic photosynthesis evolve?
Cyanobacteria (pictured above), also known as blue-green bacteria, are believed to have been the earliest organisms to engage in oxygenic photosynthesis, as plants and algae do. Under aerobic conditions, cyanobacteria are capable of performing the process of water-oxidizing photosynthesis by coupling the activity of two protein complexes, known as photosystem (PS) II and I, in a chain of events known as the Z-scheme. These protein complexes are located in the thylakoid (“pouch-like”) membrane of plants, algae, and cyanobacteria. The diagrams below illustrate what’s going on. First, here’s a schematic diagram, showing what a humble cyanobacterium looks like on the inside. The thylakoid membrane is shown in the diagram:
The ozone-oxygen cycle is the process by which ozone is continually regenerated in the Earth's stratosphere, all the while converting ultraviolet radiation (UV) into heat.
Most of the ozone production occurs in the tropical upper stratosphere and mesosphere. The total mass of ozone produced per day over the globe is about 400 million metric tons. The global mass of ozone is relatively constant at about 3 billion metric tons, meaning the Sun produces about 12% of the ozone layer each day.Ozone plays a beneficial role by absorbing most of the biologically damaging ultraviolet sunlight (called UV-B), allowing only a small amount to reach the Earth's surface. Ozone thus plays a key role in the temperature structure of the Earth's atmosphere. Without the filtering action of the ozone layer, more of the Sun's UV-B radiation would penetrate the atmosphere and would reach the Earth's surface.
In the atmosphere, Oxygen is freed by the process called photolysis. This is when high energy sunlight breaks apart oxygen-bearing molecules to produce free oxygen. One of the most well-known photolysis it the ozone cycle. O2 oxygen molecule is broken down to atomic oxygen by the ultraviolet radiation of sunlight. This free oxygen then recombines with existing O2 molecules to make O3 or ozone. This cycle is important because it helps to shield the Earth from the majority of harmful ultraviolet radiation turning it to harmless heat before it reaches the Earth’s surface.
The longer ultraviolet waves that penetrate the ozone layer are responsible for sunburn and suntan, skin cancers. They are also essential to good health, since they cause vitamin D to be formed in the body, and help in the accumulation of calcium and phosphorus. All of these substances are vital to the formation and maintenance of healthy teeth and bones.
Oxygen supports all complex (multicellular) life on our planet. However, there are good scientific reasons to believe there was no free O2 when the Earth formed about 4.6 billion years ago. This is because oxygen likes to form stable oxides with many other elements such as hydrogen, carbon, sulfur, and iron. An iron oxide you may be very familiar with is rust, and another common molecule that contains oxygen is water! Any free O2 in contact with these elements would react in a relatively short time and, therefore, disappear from the atmosphere, unless it was replenished. Evidence from sediments formed before 2.5 billion years ago supports this theory. They contain rounded grains of minerals like pyrite - an iron sulfide with the chemical formula FeS. You may know pyrite by its common name of fool's gold. Because their rounded shapes show that they must have become smooth during transport in flowing water, such as a river, they are known as ‘detrital’ minerals. These detrital grains are unstable in the presence of oxygen - the FeS molecule would quickly break down into an iron oxide and sulfate. So, our oxygen-intolerant mineral grains are rounded, showing that they were tossed around in a stream at the surface of the Earth, and thus, expose to the atmosphere. This good evidence for Earth’s early atmosphere having no free O2 - otherwise, these detrital minerals would never be preserved in the sedimentary rock record!
All this changed at about 2.4 billion years ago and, to the best of our knowledge, it happened very suddenly. Instead of detrital grains of unstable minerals geologists observe that most common sediments, such as sandstones, contain an abundance of sand grains coated with iron oxides (rust). Their sudden appearance, and the knowledge that oxygen production during photosynthesis is a pivotal biological process, has led geologists and geobiologists to coin the term ‘Great Oxidation Event’ or GOE. This event is also marked by the peak production of iron-bearing sediments known as the Banded Iron Formations (BIF). These are literally mountains of iron oxides that are being mined for steel-making.
The geochemical changes we see at the GOE could happen with just a small amount oxygen, perhaps as little as 0.01% of what we have today. It very likely took another 2 billion or so years to reach levels of 21% that support air-breathing animals. Exactly why atmospheric oxygenation took so long is not known but it is likely due to feedbacks in the way biology interacts with the atmosphere-ocean-rock system. The time lag can be explained if iron and other reduced minerals in rocks acted as an oxygen ‘buffer’. Such a lag would also have allowed early life to develop mechanisms to adapt to oxygen’s toxic effects and to develop metabolisms that make use of its incredible chemical properties. Still, understand how this all works is one of the great outstanding puzzles in the Earth sciences.
We know that free oxygen is a byproduct of the splitting of water during oxygenic photosynthesis. This requires a sophisticated light-harvesting system that can capture high-energy photons in the spectrum of visible light. Today, this is not only found in green plants but in more primitive organisms such algae and cyanobacteria. Paleontology and genetics tell us that the cyanobacteria are the most ancient group that is capable of oxygenic photosynthesis.
You would not be reading this article were it not for the remarkable properties of oxygen. This is why understanding why we have an atmosphere with exactly the right amount to support intelligent beings is such a tantalizing problem.
Geologists have followed this abiogenesis theory for a number of years. Initially, geologists were very optimistic that we would find buried in those lowest rock layers of (*Editor’s note: Several times it appears that the terms “biogenesis” and “abiogenesis” are used almost interchangeably. I have checked the videotape for this section and can state with certainty that the gentlemen are quoted correctly, which does not discount the possibility that they may have misspoken.)the earth—this bathtub ring, if you will, from this reducing atmosphere—this very much different atmosphere. And even as much as 20 years ago, geologists were claiming that those rocks really did prove the absence of oxygen in this very unusual condition.
Over the last 20 years though, geologists have more carefully studied those lower rock layers of the earth called the Precambrian strata and they have concluded generally that those oldest rocks are very rich in oxygen. For example, one of the oldest sedimentary rocks described and discovered by geologists on the earth has banded iron formation, and the major element in this rock is not iron, but is oxygen. And there are very many oxygen-rich rocks buried in the earth.
In fact, geologists have recently discovered sulfate deposits, sulfur and oxygen combined together and not sulfur combined with a metal such as lead or zinc. And geologists have discovered these oxidized iron deposits. Evidence of oxidation like soil development and many things are causing the evolutionists to question the whole reducing atmosphere scenario.
Carbon dioxide makes up less than one percent of the atmosphere. What good is such a small amount? Without it, plant life would die. That small amount is what plants need to take in, giving off oxygen in return. Humans and
animals breathe in the oxygen and exhale carbon dioxide. An increasing percentage of carbon dioxide in the atmosphere would tend to be harmful to humans and animals. A decreasing percentage could not support plant life. What a marvelous, precise, self-sustaining cycle has been arranged for plant, animal, and human life! 3 In addition to being a protective shell, the atmosphere keeps the warmth of the earth from being lost to the coldness of space. And the atmosphere is itself kept from escaping by the earth's gravitational pull. That gravity is just strong enough to accomplish this, but not so strong that our freedom of movement is hampered.
Assuming that the planetary atmosphere was not so reducing as to allow NH3 to be a major component of the atmosphere, the only known abiotic sources of fixed inorganic nitrogen would have included lightning, bolide impacts and possibly hydrothermal reactions in a reduced environment. At most, these reactions would have delivered approximately 1 Tmol yr−1; a flux that would have constrained CO2 fixation to less than 0.1% of modern values
Electrons, life and the evolution of Earth's oxygen cycle
2008 May 16
Assuming that the planetary atmosphere was not so reducing as to allow NH3 to be a major component of the atmosphere, the only known abiotic sources of fixed inorganic nitrogen would have included lightning, bolide impacts and possibly hydrothermal reactions in a reduced environment. At most, these reactions would have delivered a flux that would have constrained CO2 fixation to less than 0.1% of modern values. 5 That is, the initial reduction of Nitrogen Gas N2 to Ammonium NH4+ is at the expense of the oxidation of organic carbon to inorganic carbon, ( nitrogen fixation can be thought of as a type of respiratory pathway; however, unlike other respiratory pathways, it consumes rather than produces energy. ) while the oxidation of NH4+ to Nitrate NO3− is coupled to the reduction of inorganic carbon to organic matter and the reduction of NO−3 to N2 is coupled to the oxidation of organic matter to inorganic carbon. All the three pathways are related to oxygen;
The destructive effect of oxygen, ultraviolet radiation from the sun and the short duration of an optimal atmosphere for their production, makes it unlikely that significant quantities of viable nucleotides and amino acids could ever accumulate in the primitive ocean. 6
1) http://www.ideacenter.org/contentmgr/showdetails.php/id/838
2. http://crossexamined.org/four-ways-the-earth-is-fine-tuned-for-life/
3) https://groups.google.com/forum/#!msg/talk.origins/6QlVBAGD_GY/00aLE8_XpC8J
4. http://www.sciencealert.com/volcanoes-shaped-life-on-earth
5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2606772/
6. http://xwalk.ca/origin.html
7. http://nideffer.net/proj/Hawking/early_proto/orgel.html
8. http://sci-hub.ren/http://www.nrcresearchpress.com/doi/abs/10.1139/e76-119#.WpiFmh3waUk
9. https://www.nature.com/scitable/knowledge/library/earth-s-earliest-climate-24206248
Further reading:
http://www.scientificpsychic.com/etc/timeline/atmosphere-composition.html
http://en.wikipedia.org/wiki/Ozone-oxygen_cycle
http://www.universetoday.com/61080/oxygen-cycle/
http://www.ozonelayer.noaa.gov/science/basics.htm
http://science.howstuffworks.com/dictionary/physics-terms/ultraviolet-radiation-info.htm
A Big Problem for Naturalistic Explanations of Life's Origins: Zircon Shows Oxygen Present in the Early Earth
http://www.evolutionnews.org/2011/12/post_34053831.html
Last edited by Otangelo on Sun May 15, 2022 10:40 am; edited 27 times in total