scholarly journals Atmospheric oxygenation of the early earth and earth-like planets driven by competition between land and seafloor weathering

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Yasuto Watanabe ◽  
Eiichi Tajika
Keyword(s):  
Chemical Weathering ◽  
Atmospheric Oxygen ◽  
Oxygenic Photosynthesis ◽  
Biogeochemical Model ◽  
Planetary Surface ◽  
Oxygen Levels ◽  
Earth Like Planets ◽  
Continental Weathering ◽  
Continental Growth ◽  
Marine Biosphere

AbstractOxygen is a potential biosignature for terrestrial Earth-like planets. The primary source of oxygen on Earth is oxygenic photosynthesis, which may be limited by the supply of riverine phosphorus. Therefore, phosphorus supply from the chemical weathering of continents is crucial for the evolution of pO2. Chemical weathering occurs on both the continents and seafloor and stabilizes the climate, but phosphorus is only supplied by continental weathering. The amount of continental weathering relative to seafloor weathering may be critical for primary productivity and pO2. The area of continents could change as a result of continental growth and the amount of ocean mass on the planetary surface, and these factors could be very different on extrasolar Earth-like planets. Here, we investigated the effects of continental and seafloor weathering on the atmospheric oxygen levels, in terms of the Earth-like phosphorus-limited marine biosphere. We used a simple biogeochemical model and investigated a possible relationship between continental growth and atmospheric oxygen levels. We found that the atmosphere could evolve totally different redox conditions (an abrupt rise of atmospheric oxygen levels or a reducing condition to form organic haze) caused by continental growth, which changes the relative contribution of silicate weathering feedback from seafloor to continent. We also found that conditions with lower solar luminosity and a larger land fraction provided a preferable condition for the phosphorus-limited marine biosphere to produce high levels of oxygen in the atmosphere. We also found that the atmospheric oxygen level is strongly affected by the activity of the anaerobic marine microbial ecosystem. Our results suggest that the area of land on the planetary surface may be crucial for achieving high oxygen levels in a phosphorus-limited marine biosphere. These results contribute to the fundamental understanding of the general behaviors of Earth-like planets with oceans and an Earth-like marine biosphere.

A case for low atmospheric oxygen levels during Earth's middle history

2018 ◽  
Vol 2 (2) ◽  
pp. 149-159 ◽  
Author(s):  
Noah J. Planavsky ◽  
Devon B. Cole ◽  
Terry T. Isson ◽  
Christopher T. Reinhard ◽  
Peter W. Crockford ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Conceptual Framework ◽  
Environmental Conditions ◽  
Atmospheric Oxygen ◽  
Critical Factor ◽  
Planetary Surface ◽  
Surface Oxygen ◽  
Oxygen Levels ◽  
Early Diversification ◽  
Atmospheric Level

The oxygenation of the atmosphere — one of the most fundamental transformations in Earth's history — dramatically altered the chemical composition of the oceans and provides a compelling example of how life can reshape planetary surface environments. Furthermore, it is commonly proposed that surface oxygen levels played a key role in controlling the timing and tempo of the origin and early diversification of animals. Although oxygen levels were likely more dynamic than previously imagined, we make a case here that emerging records provide evidence for low atmospheric oxygen levels for the majority of Earth's history. Specifically, we review records and present a conceptual framework that suggest that background oxygen levels were below 1% of the present atmospheric level during the billon years leading up to the diversification of early animals. Evidence for low background oxygen levels through much of the Proterozoic bolsters the case that environmental conditions were a critical factor in controlling the structure of ecosystems through Earth's history.

scholarly journals Insights into the evolution of oxygenic photosynthesis from a phylogenetically novel, low-light cyanobacterium

2018 ◽  
Author(s):  
Christen L. Grettenberger ◽  
Dawn Y. Sumner ◽  
Kate Wall ◽  
C. Titus Brown ◽  
Jonathan Eisen ◽  
...  
Keyword(s):  
Atmospheric Oxygen ◽  
Evolutionary Model ◽  
Reaction Centers ◽  
Oxygenic Photosynthesis ◽  
Oxygen Production ◽  
Crown Group ◽  
Low Light ◽  
Extrinsic Proteins ◽  
Structural Parts ◽  
Life On Earth

AbstractAtmospheric oxygen level rose dramatically around 2.4 billion years ago due to oxygenic photosynthesis by the Cyanobacteria. The oxidation of surface environments permanently changed the future of life on Earth, yet the evolutionary processes leading to oxygen production are poorly constrained. Partial records of these evolutionary steps are preserved in the genomes of organisms phylogenetically placed between non-photosynthetic Melainabacteria, crown-group Cyanobacteria, and Gloeobacter, representing the earliest-branching Cyanobacteria capable of oxygenic photosynthesis. Here, we describe nearly complete, metagenome assembled genomes of an uncultured organism phylogenetically placed between the Melainabacteria and crown-group Cyanobacteria, for which we propose the name Candidatus Aurora vandensis {au.rora Latin noun dawn and vand.ensis, originating from Vanda}.The metagenome assembled genome of A. vandensis contains homologs of most genes necessary for oxygenic photosynthesis including key reaction center proteins. Many extrinsic proteins associated with the photosystems in other species are, however, missing or poorly conserved. The assembled genome also lacks homologs of genes associated with the pigments phycocyanoerethrin, phycoeretherin and several structural parts of the phycobilisome. Based on the content of the genome, we propose an evolutionary model for increasing efficiency of oxygenic photosynthesis through the evolution of extrinsic proteins to stabilize photosystem II and I reaction centers and improve photon capture. This model suggests that the evolution of oxygenic photosynthesis may have significantly preceded oxidation of Earth’s atmosphere due to low net oxygen production by early Cyanobacteria.

Global biosphere primary productivity over the last 800,000 years reconstructed from the triple-isotope composition of dioxygen trapped in polar ice cores

2021 ◽  
Author(s):  
Ji-Woong Yang ◽  
Amaëlle Landais ◽  
Margaux Brandon ◽  
Thomas Blunier ◽  
Frédéric Prié ◽  
...  
Keyword(s):  
Primary Productivity ◽  
Isotope Composition ◽  
Atmospheric Oxygen ◽  
Ice Cores ◽  
Oxygenic Photosynthesis ◽  
Time Interval ◽  
Polar Ice ◽  
Future Evolution ◽  
Glacial Stage ◽  
Glacial Periods

<p>The primary production, or oxygenic photosynthesis of the global biosphere, is one of the main source and sink of atmospheric oxygen (O<sub>2</sub>) and carbon dioxide (CO<sub>2</sub>), respectively. There has been a growing number of evidence that global gross primary productivity (GPP) varies in response to climate change. It is therefore important to understand the climate- and/or environment controls of the global biosphere primary productivity for better predicting the future evolution of biosphere carbon uptake. The triple-isotope composition of O<sub>2</sub> (Δ<sup>17</sup>O of O<sub>2</sub>) trapped in polar ice cores allows us to trace the past changes of global biosphere primary productivity as far back as 800,000 years before present (800 ka). Previously available Δ<sup>17</sup>O of O<sub>2</sub> records over the last ca. 450 ka show relatively low and high global biosphere productivity over the last five glacial and interglacial intervals respectively, with a unique pattern over Termination V (TV) - Marine Isotopic Stage (MIS) 11, as biosphere productivity at the end of TV is ~ 20 % higher than the four younger ones (Blunier et al., 2012; Brandon et al., 2020). However, questions remain on (1) whether the concomitant changes of global biosphere productivity and CO<sub>2</sub> were the pervasive feature of glacial periods over the last 800 ka, and (2) whether the global biosphere productivity during the “lukewarm” interglacials before the Mid-Brunhes Event (MBE) were lower than those after the MBE.<br>Here, we present an extended composite record of Δ<sup>17</sup>O of O<sub>2</sub> covering the last 800 ka, based on new Δ<sup>17</sup>O of O<sub>2</sub> results from the EPICA Dome C and reconstruct the evolution of global biosphere productivity over that time interval using the independent box models of Landais et al. (2007) and Blunier et al. (2012). We find that the glacial productivity minima occurred nearly synchronously with the glacial CO<sub>2</sub> minima at mid-glacial stage; interestingly millennia before the sea level reaches their minima. Following the mid-glacial minima, we also show slight productivity increases at the full-glacial stages, before deglacial productivity rises. Comparison of reconstructed interglacial productivity demonstrates a slightly higher productivity over the post-MBE (MISs 1, 5, 7, 9, and 11) than pre-MBE ones (MISs 13, 15, 17, and 19). However, the mean difference between post- and pre-MBE interglacials largely depends on the box model used for productivity reconstruction.</p>

Plants at Sub-Atmospheric Oxygen-Levels

Nature ◽  
1963 ◽  
Vol 198 (4887) ◽  
pp. 1288-1290 ◽  
Author(s):  
S. M. SIEGEL ◽  
L. A. ROSEN ◽  
C. GIUMARRO
Keyword(s):  
Atmospheric Oxygen ◽  
Oxygen Levels

scholarly journals Metabolic Activity of Human Embryos after Thawing Differs in Atmosphere with Different Oxygen Concentrations

2020 ◽  
Vol 9 (8) ◽  
pp. 2609
Author(s):  
Michal Ješeta ◽  
Andrea Celá ◽  
Jana Žáková ◽  
Aleš Mádr ◽  
Igor Crha ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Oxygen Concentration ◽  
Atmospheric Oxygen ◽  
Blastocyst Stage ◽  
Human Embryos ◽  
Total Amino Acid ◽  
Oxygen Levels ◽  
Amino Acid Turnover ◽  
Cultivation Environment

The vitrification of human embryos is more and more frequently being utilized as a method of assisted reproduction. For this technique, gentle treatment of the embryos after thawing is crucial. In this study, the balance of amino acids released to/consumed from the cultivation media surrounding the warmed embryos was observed in the context of a cultivation environment, which was with the atmospheric oxygen concentration ≈20% or with a regulated oxygen level—hysiological (5%). It is the first time that total amino acid turnover in human embryos after their freezing at post compaction stages has been evaluated. During this study, progressive embryos (developed to blastocyst stage) and stagnant embryos (without developmental progression) were analyzed. It was observed that the embryos cultivated in conditions of physiological oxygen levels (5% oxygen) showed a significantly lower consumption of amino acids from the cultivation media. Progressively developing embryos also had significantly lower total amino acid turnovers (consumption and production of amino acids) when cultured in conditions with physiological oxygen levels. Based on these results it seems that a cultivation environment with a reduced oxygen concentration decreases the risk of degenerative changes in the embryos after thawing. Therefore, the cultivation of thawed embryos in an environment with physiological oxygen levels may preclude embryonal stagnation, and can support the further development of human embryos after their thawing.

scholarly journals No evidence for high atmospheric oxygen levels 1,400 million years ago

2016 ◽  
Vol 113 (19) ◽  
pp. E2550-E2551 ◽  
Author(s):  
Noah J. Planavsky ◽  
Devon B. Cole ◽  
Christopher T. Reinhard ◽  
Charles Diamond ◽  
Gordon D. Love ◽  
...  
Keyword(s):  
Atmospheric Oxygen ◽  
Oxygen Levels

scholarly journals The oxic degradation of sedimentary organic matter 1400 Ma constrains atmospheric oxygen levels

2017 ◽  
Vol 14 (8) ◽  
pp. 2133-2149 ◽  
Author(s):  
Shuichang Zhang ◽  
Xiaomei Wang ◽  
Huajian Wang ◽  
Emma U. Hammarlund ◽  
Jin Su ◽  
...  
Keyword(s):  
Atmospheric Oxygen ◽  
Carbon Mineralization ◽  
Black Shales ◽  
Depositional Environments ◽  
Iron Speciation ◽  
North China Block ◽  
High Hydrogen ◽  
Oxygen Levels ◽  
The North ◽  
Xiamaling Formation

Abstract. We studied sediments from the ca. 1400 million-year-old Xiamaling Formation from the North China block. The upper unit of this formation (unit 1) deposited mostly below storm wave base and contains alternating black and green-gray shales with very distinct geochemical characteristics. The black shales are enriched in redox-sensitive trace metals, have high concentrations of total organic carbon (TOC), high hydrogen index (HI) and iron speciation indicating deposition under anoxic conditions. In contrast, the green-gray shales show no trace metal enrichments, have low TOC, low HI and iron speciation consistent with an oxygenated depositional setting. Altogether, unit 1 displays alternations between oxic and anoxic depositional environments, driving differences in carbon preservation consistent with observations from the modern ocean. We combined our TOC and HI results to calculate the differences in carbon mineralization and carbon preservation by comparing the oxygenated and anoxic depositional environments. Through comparisons of these results with modern sedimentary environments, and by use of a simple diagenetic model, we conclude that the enhanced carbon mineralization under oxygenated conditions in unit 1 of the Xiamaling Formation required a minimum of 4 to 8 % of present-day atmospheric levels (PAL) of oxygen. These oxygen levels are higher than estimates based on chromium isotopes and reinforce the idea that the environment contained enough oxygen for animals long before their evolution.

Reduction of acetylene by stationary cultures of free-living Rhizobium sp. under atmospheric oxygen levels

1976 ◽  
Vol 22 (7) ◽  
pp. 949-952 ◽  
Author(s):  
William R. Evans ◽  
Donald L. Keister
Keyword(s):  
Atmospheric Oxygen ◽  
Maximal Activity ◽  
Free Living ◽  
Oxygen Levels ◽  
Specific Activities ◽  
Rhizobium Sp ◽  
Oxygen Concentrations

The reduction of acetylene to ethylene by stationary (non-shaking) cultures of free-living rhizobia under atmospheric oxygen levels has been demonstrated. Under these conditions the development of the activity is inhibited by 10 mM NH4Cl and about 20% of oxygen is required for maximal activity. When the stationary cultures were shaken, oxygen concentrations of 1% and higher were found to be inhibitory. Specific activities of 20 and 40 nmol of acetylene reduced h−1 mg−1 protein were observed.

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