scholarly journals Ice core evidence for atmospheric oxygen decline since the Mid-Pleistocene transition

2021 ◽  
Vol 7 (51) ◽  
Author(s):  
Yuzhen Yan ◽  
Edward J. Brook ◽  
Andrei V. Kurbatov ◽  
Jeffrey P. Severinghaus ◽  
John A. Higgins
Keyword(s):  
Atmospheric Oxygen ◽  
Ice Core

scholarly journals Planetary fertility during the past 400 ka based on the triple isotope composition of O<sub>2</sub> in trapped gases from the Vostok ice core

2012 ◽  
Vol 8 (5) ◽  
pp. 1509-1526 ◽  
Author(s):  
T. Blunier ◽  
M. L. Bender ◽  
B. Barnett ◽  
J. C. von Fischer
Keyword(s):  
Isotope Exchange ◽  
Isotope Composition ◽  
Atmospheric Oxygen ◽  
Ice Core ◽  
Fractionation Process ◽  
Factors Affecting ◽  
Mass Independent Fractionation ◽  
Oxygen Cycle ◽  
Steady State Model ◽  
O2 Production

Abstract. The productivity of the biosphere leaves its imprint on the isotopic composition of atmospheric oxygen. Ultimately, atmospheric oxygen, through photosynthesis, originates from seawater. Fractionations during the passage from seawater to atmospheric O2 and during respiration affect δ17O approximately half as much as δ18O. An "anomalous" (also termed mass independent) fractionation process changes δ17O about 1.7 times as much as δ18O during isotope exchange between O2 and CO2 in the stratosphere. The relative rates of biological O2 production and stratospheric processing determine the relationship between δ17O and δ18O of O2 in the atmosphere. Variations of this relationship thus allow us to estimate changes in the rate of O2 production by photosynthesis versus the rate of O2–CO2 isotope exchange in the stratosphere. However, the analysis of the 17O anomaly is complicated because each hydrological and biological process fractionates δ17O and δ18O in slightly different proportions. In this study we present O2 isotope data covering the last 400 ka (thousand years) from the Vostok ice core. We reconstruct oxygen productivities from the triple isotope composition of atmospheric oxygen with a box model. Our steady state model for the oxygen cycle takes into account fractionation during photosynthesis and respiration by the land and ocean biosphere, fractionation during the hydrologic cycle, and fractionation when oxygen passes through the stratosphere. We consider changes of fractionation factors linked to climate variations, taking into account the span of estimates of the main factors affecting our calculations. We find that ocean oxygen productivity was within 20% of the modern value throughout the last 400 ka. Given the presumed reduction in terrestrial oxygen productivity, the total oxygen production during glacials was likely reduced.

scholarly journals Anomalous flow below 2700 m in the EPICA Dome C ice core detected using δ<sup>18</sup>O of atmospheric oxygen measurements

2007 ◽  
Vol 3 (1) ◽  
pp. 63-93 ◽  
Author(s):  
G. B. Dreyfus ◽  
F. Parrenin ◽  
B. Lemieux-Dudon ◽  
G. Durand ◽  
V. Masson-Delmotte ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Northern Hemisphere ◽  
Marine Sediment ◽  
Atmospheric Oxygen ◽  
Ice Core ◽  
The Core ◽  
Sediment Records ◽  
Ice Core Record ◽  
Orbital Precession ◽  
Oxygen Measurements

Abstract. While there are no indications of mixing back to 800 000 years in the EPICA Dome C ice core record, comparison with marine sediment records shows significant differences in the timing and duration of events prior to stage 11 (~430 ka, thousand of years before 1950). A relationship between the isotopic composition of atmospheric oxygen (δ18O of O2, noted δ18Oatm) and daily northern hemisphere summer insolation has been observed for the youngest four climate cycles. Here we use this relationship with new δ18O of O2 measurements to show that anomalous flow in the bottom 500 m of the core distorts the duration of events by up to a factor of 2. By tuning δ18Oatm to orbital precession we derive a corrected thinning function and present a revised age scale for the interval corresponding to Marine Isotope Stages 11–20 in the EPICA Dome C ice core. Uncertainty in the phasing of δ18Oatm with respect to insolation variations in the precession band limits the accuracy of this new agescale to ±6 kyr (thousand of years). The previously reported ~30 kyr duration of interglacial stage 11 is unchanged. In contrast, the duration of stage 15.1 is reduced by a factor of 2, from 31 to 16 kyr.

Leaf hydraulic design influences the development of isotope gradients in leaves, but are there subsequent effects on isotopes of atmospheric oxygen?

2021 ◽  
Author(s):  
Margaret Barbour
Keyword(s):  
Water Movement ◽  
Atmospheric Oxygen ◽  
Ice Core ◽  
Experimental Studies ◽  
Leaf Water ◽  
Isotope Enrichment ◽  
Terrestrial Plants ◽  
Considerable Uncertainty ◽  
Modelling Framework ◽  
Hydraulic Design

&lt;p&gt;Leaf water becomes enriched in heavier isotopes during transpiration, with the degree of enrichment dependent on evaporative conditions. However, there has been considerable uncertainty regarding the importance of gradients in isotope enrichment within leaves (i.e. a P&amp;#233;clet effect).&amp;#160; That is, experimental studies show that evidence is approximately equally divided between the P&amp;#233;clet effect being important and being irrelevant for leaves. Our recent work demonstrates a link between the hydraulic design of leaves and the presence or otherwise of a P&amp;#233;clet effect.&amp;#160; That is, with prior knowledge of the pathways of water movement through leaves, the most appropriate modelling framework can be selected and uncertainty in interpretation and prediction reduced.&lt;/p&gt;&lt;p&gt;Reducing uncertainty is important because the H&lt;sub&gt;2&lt;/sub&gt;&lt;sup&gt;18&lt;/sup&gt;O composition of leaves is passed on to oxygen atoms in O&lt;sub&gt;2&lt;/sub&gt; and CO&lt;sub&gt;2&lt;/sub&gt; so terrestrial plants strongly influence isotopic composition of the atmosphere. Of particular interest is the interpretation of the Dole effect, the oxygen isotopic imbalance between atmospheric O&lt;sub&gt;2&lt;/sub&gt; and seawater.&amp;#160; The ice core record of the Dole effect has been interpreted as an integrative proxy for the global balance between terrestrial and oceanic productivity, or more recently as an indication of the migration of terrestrial productivity towards and away from the equator.&amp;#160; Both interpretations depend on highly uncertain leaf water isotope enrichment models. In light of the link between leaf hydraulic design and the P&amp;#233;clet effect, should we expect differences between species in the &lt;sup&gt;18&lt;/sup&gt;O of O&lt;sub&gt;2&lt;/sub&gt; produced by photosynthesis?&amp;#160; Do we need to reinterpret the Dole effect?&lt;/p&gt;

Sequence of events at high resolution during deglaciations over the last 800ka from the EDC ice core

2021 ◽  
Author(s):  
Antoine Grisart ◽  
amaelle landais ◽  
barbara stenni ◽  
ilaria crotti ◽  
valérie masson delmotte ◽  
...  
Keyword(s):  
High Resolution ◽  
Isotopic Composition ◽  
Elemental Composition ◽  
Water Cycle ◽  
Atmospheric Oxygen ◽  
Ice Core ◽  
Ice Cores ◽  
Climatic Conditions ◽  
Low Latitude ◽  
Sequence Of Events

&lt;p&gt;The EPICA Dome C (EDC) ice core has been drilled from 1996 to 2004. Its study revealed a unique 800 ka long continuous climatic record including 9 deglaciations. Ice cores contain numerous proxies in the ice and in the air trapped in bubbles (chronological constraints, greenhouse gases concentration, local temperature proxies, mid to low latitude climate proxies). Here, we focus on information provided by the isotopic (and elemental) composition of water and oxygen archived in both ice and gas matrix. On one hand, the water isotopic composition brings information on past temperatures and water cycle re-organizations:&amp;#160;&amp;#160; d&lt;sup&gt;18&lt;/sup&gt;O or dD records past temperature, whereas the combination of d&lt;sup&gt;18&lt;/sup&gt;O with dD or d&lt;sup&gt;17&lt;/sup&gt;O provide information on the past water cycle organization through d-excess and &lt;sup&gt;17&lt;/sup&gt;O-excess linked to climatic conditions of the evaporative regions. On the other hand, the elemental composition of oxygen expressed in the O&lt;sub&gt;2&lt;/sub&gt;/N&lt;sub&gt;2&lt;/sub&gt; ratio provides key information for orbital dating over the last 800 ka in complement with the isotopic composition of atmospheric oxygen (d&lt;sup&gt;18&lt;/sup&gt;O of O&lt;sub&gt;2&lt;/sub&gt; or d&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;atm&lt;/sub&gt;) which is related as well to the low latitude water cycle.&lt;/p&gt;&lt;p&gt;In this study, we present new high resolution records of water isotopes (d&lt;sup&gt;18&lt;/sup&gt;O, d-excess and &lt;sup&gt;17&lt;/sup&gt;O-excess) as well as high resolution measurements of O&lt;sub&gt;2&lt;/sub&gt;/N&lt;sub&gt;2&lt;/sub&gt; and d&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;atm&lt;/sub&gt; over the last 9 deglaciations on the EDC ice core. We first use the high resolution records of O&lt;sub&gt;2&lt;/sub&gt;/N&lt;sub&gt;2&lt;/sub&gt; and d&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;atm&lt;/sub&gt; to improve absolute dating constrain over the glacial terminations and discuss the link between orbital forcing and climate variations recorded in the EDC ice core. In a second part, we use d-excess, &lt;sup&gt;17&lt;/sup&gt;O-excess and d&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;atm&lt;/sub&gt; to constrain the relative chronology of high vs low latitude climatic events at sub-millennial scale over past deglaciations.&lt;/p&gt;

scholarly journals Anomalous flow below 2700 m in the EPICA Dome C ice core detected using δ<sup>18</sup>O of atmospheric oxygen measurements

2007 ◽  
Vol 3 (2) ◽  
pp. 341-353 ◽  
Author(s):  
G. B. Dreyfus ◽  
F. Parrenin ◽  
B. Lemieux-Dudon ◽  
G. Durand ◽  
V. Masson-Delmotte ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Northern Hemisphere ◽  
Marine Sediment ◽  
Atmospheric Oxygen ◽  
Ice Core ◽  
The Core ◽  
Sediment Records ◽  
Ice Core Record ◽  
Orbital Precession ◽  
Oxygen Measurements

Abstract. While there are no indications of mixing back to 800 000 years in the EPICA Dome C ice core record, comparison with marine sediment records shows significant differences in the timing and duration of events prior to stage 11 (~430 ka, thousands of years before 1950). A relationship between the isotopic composition of atmospheric oxygen (δ18O of O2, noted δ18Oatm) and daily northern hemisphere summer insolation has been observed for the youngest four climate cycles. Here we use this relationship with new δ18O of O2 measurements to show that anomalous flow in the bottom 500 m of the core distorts the duration of events by up to a factor of 2. By tuning δ18Oatm to orbital precession we derive a corrected thinning function and present a revised age scale for the interval corresponding to Marine Isotope Stages 11–20 in the EPICA Dome C ice core. Uncertainty in the phasing of δ18Oatm with respect to insolation variations in the precession band limits the accuracy of this new agescale to ±6 kyr (thousand of years). The previously reported ~30 kyr duration of interglacial stage 11 is unchanged. In contrast, the duration of stage 15.1 is reduced by a factor of 2, from 31 to 16 kyr.

scholarly journals Planetary fertility during the past 400 ka based on the triple isotope composition of O<sub>2</sub> in trapped gases from the Vostok ice core

2012 ◽  
Vol 8 (1) ◽  
pp. 435-479
Author(s):  
T. Blunier ◽  
M. L. Bender ◽  
B. Barnett ◽  
J. C. von Fisher
Keyword(s):  
Isotope Composition ◽  
Atmospheric Oxygen ◽  
Ice Core ◽  
Co2 Exchange ◽  
Slight Reduction ◽  
Fractionation Process ◽  
Factors Affecting ◽  
Steady State Model ◽  
Mass Dependent ◽  
O2 Production

Abstract. The productivity of the biosphere leaves its imprint on the isotopic composition of atmospheric oxygen. Ultimately atmospheric oxygen, through photosynthesis, originates from seawater. Fractionations during the passage from seawater to atmospheric O2 and during respiration are mass dependent, affecting δ17O about half as much as δ18O. An "anomalous" (also termed mass independent) fractionation process changes δ17O about 1.7 times as much as δ18O during isotope exchange between O2 and CO2 in the stratosphere. The relative rates of biological O2 production and stratospheric processing determine the relationship between δ17O and δ18O of O2 in the atmosphere. Variations of this relationship thus allow us to estimate changes in the rate of mass dependent O2 production by photosynthesis vs. the rate of mass independent O2-CO2 exchange in the stratosphere. However, the analysis of the 17O anomaly is complicated because each hydrological and biological process influencing δ17O and δ18O fractionates 17O and 18O in slightly different proportions. In this study we present oxygen data covering the last 400 kyr from the Vostok ice core. We reconstruct oxygen productivities from the triple isotope composition of atmospheric oxygen with a box model. Our steady state model for the oxygen cycle takes into account fractionation during photosynthesis and respiration of the land and ocean biosphere as well as fractionation when oxygen passes through the stratosphere. We consider changes of fractionation factors linked to climate variations taking into account the span of estimates of the main factors affecting our calculations. We find that ocean oxygen productivity was likely elevated relative to modern during glacials. However, this increase probably did not fully compensate for a reduction in land ocean productivity resulting in a slight reduction in total oxygen production during glacials.

Oxygen-to-nitrogen ratios in 1.5-million-year-old ice cores from Allan Hills Blue Ice Areas: implications for the long-term atmospheric oxygen concentrations

2020 ◽  
Author(s):  
Yuzhen Yan ◽  
Michael Bender ◽  
Edward Brook ◽  
Heather Clifford ◽  
Preston Kemeny ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Atmospheric Oxygen ◽  
Ice Core ◽  
Ice Cores ◽  
The Past ◽  
Gas Trapping ◽  
Rate Of Decline ◽  
Gas Loss ◽  
Oxygen Concentrations

&lt;p&gt;Gases preserved in ice cores provide a potential direct archive for atmospheric oxygen. Yet, oxygen-to-nitrogen ratios in ice cores (expressed as &amp;#948;O&lt;sub&gt;2&lt;/sub&gt;/N&lt;sub&gt;2&lt;/sub&gt;) are modified by a number of processes related to gas trapping and gas losses in the ice. Such complications have long hindered the use of ice core &amp;#948;O&lt;sub&gt;2&lt;/sub&gt;/N&lt;sub&gt;2&lt;/sub&gt; to derive true atmospheric oxygen concentrations. Recently, a persistent decline in &amp;#948;O&lt;sub&gt;2&lt;/sub&gt;/N&lt;sub&gt;2&lt;/sub&gt;, observed in four different ice cores (GISP2, Vostok, Dome F, and EDC), is interpreted to reflect decreasing atmospheric O&lt;sub&gt;2&lt;/sub&gt; concentrations over the late Pleistocene (Stolper et al., 2016). The rate of &amp;#948;O&lt;sub&gt;2&lt;/sub&gt;/N&lt;sub&gt;2&lt;/sub&gt; change is -8.4&amp;#177;0.2 &amp;#8240;/Myr (1&amp;#963;). Using new measurements made on EDC samples stored at -50 &amp;#176;C and therefore free from gas loss, Extier et al (2018) confirms the decrease in &amp;#948;O&lt;sub&gt;2&lt;/sub&gt;/N&lt;sub&gt;2&lt;/sub&gt; with a slope of -7.0&amp;#177;0.6&amp;#8240;/Myr (1&amp;#963;).&lt;/p&gt;&lt;p&gt;Here, we present new &amp;#948;O&lt;sub&gt;2&lt;/sub&gt;/N&lt;sub&gt;2&lt;/sub&gt; measurements made on 1.5-million-year-old blue ice cores from Allan Hills Blue Ice Areas, East Antarctica. We use argon-to-nitrogen ratios (&amp;#948;Ar/N&lt;sub&gt;2&lt;/sub&gt;) in the ice to correct for the fractionations during bubble close-off and gas losses. In those processes, &amp;#948;Ar/N&lt;sub&gt;2&lt;/sub&gt; is fractionated in a fashion similar to &amp;#948;O&lt;sub&gt;2&lt;/sub&gt;/N&lt;sub&gt;2&lt;/sub&gt; (Huber et al., 2006; Severinghaus and Battle, 2006). Paired &amp;#948;O&lt;sub&gt;2&lt;/sub&gt;/N&lt;sub&gt;2&lt;/sub&gt;-&amp;#948;Ar/N&lt;sub&gt;2&lt;/sub&gt; values measured from the same sample were classified into three different time slices: 1.5 Ma (million years old), 950 ka, and 490 ka. Between 950 ka and 490 ka, we observe a decline in &amp;#948;O&lt;sub&gt;2&lt;/sub&gt;/N&lt;sub&gt;2&lt;/sub&gt; similar to that observed in the aforementioned deep ice cores. This observation gives us confidence in the validity of the Allan Hills blue ice &amp;#948;O&lt;sub&gt;2&lt;/sub&gt;/N&lt;sub&gt;2&lt;/sub&gt; records. Between 1.5 Ma and 950 ka, however, there is no statistically significant trend in ice core &amp;#948;O&lt;sub&gt;2&lt;/sub&gt;/N&lt;sub&gt;2&lt;/sub&gt;. Our results show a surprising lack of variability from 1.5 to 0.95 Ma; even during the past ~0.9 Ma, the rate of decline was very slow.&lt;/p&gt;

Phanerozoic Oxygen

2017 ◽  
Author(s):  
Donald Eugene Canfield
Keyword(s):  
Oxygen Consumption ◽  
Organic Carbon ◽  
Sea Level ◽  
Time Scale ◽  
Atmospheric Oxygen ◽  
Sea Level Change ◽  
Oxygen Production ◽  
Level Change ◽  
History Of ◽  
Geologic Processes

This chapter discusses the modeling of the history of atmospheric oxygen. The most recently deposited sediments will also be the most prone to weathering through processes like sea-level change or uplift of the land. Thus, through rapid recycling, high rates of oxygen production through the burial of organic-rich sediments will quickly lead to high rates of oxygen consumption through the exposure of these organic-rich sediments to weathering. From a modeling perspective, rapid recycling helps to dampen oxygen changes. This is important because the fluxes of oxygen through the atmosphere during organic carbon and pyrite burial, and by weathering, are huge compared to the relatively small amounts of oxygen in the atmosphere. Thus, all of the oxygen in the present atmosphere is cycled through geologic processes of oxygen liberation (organic carbon and pyrite burial) and consumption (weathering) on a time scale of about 2 to 3 million years.

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