scholarly journals A centrifugal ice microtome for measurements of atmospheric CO<sub>2</sub> on air trapped in polar ice cores

2012 ◽  
Vol 5 (5) ◽  
pp. 7867-7897
Author(s):  
B. Bereiter ◽  
T. F. Stocker ◽  
H. Fischer
Keyword(s):  
Vacuum Chamber ◽  
Ice Cores ◽  
Magnetic Bearings ◽  
Optimized Design ◽  
Polar Ice ◽  
Trapped Air ◽  
Ice Powder ◽  
Analytical System ◽  
Replicate Measurements ◽  
Current Systems

Abstract. For atmospheric CO2 reconstructions using ice cores, the technique to release the trapped air from the ice samples is crucial for the precision and accuracy of the measurements. We present here a new dry extraction technique in combination with a new gas analytical system that together show significant improvements with respect to current systems. Ice samples (3–15 g) are pulverized using a novel Centrifugal Ice Microtome (CIM) by shaving the ice in a cooled vacuum chamber (−27 °C) in which no friction occurs due to the use of magnetic bearings. Both, the shaving principle of the CIM and the use of magnetic bearings have not been applied so far in this field. Shaving the ice samples produces finer ice powder and releases a minimum of 90% of the trapped air compared to 50%–70% when needle crushing is employed. In addition, the friction-free motion with an optimized design to reduce contaminations of the inner surfaces of the device result in a reduced system offset of about 2.0 ppmv compared to 4.9ppmv. The gas analytical part shows a factor two higher precision than our corresponding part of the previous system and all processes except the loading and cleaning of the CIM now run automatically. Compared to our previous system the new system shows a 3 times better measurement reproducibility of about 1.1 ppmv (1σ) which is similar to the best reproducibility of other systems applied in this field. With this high reproducibility, replicate measurements are not required anymore for most prospective measurement campaigns resulting in a possible output of 12–20 measurements per day compared to a maximum of 6 with other systems.

scholarly journals A centrifugal ice microtome for measurements of atmospheric CO<sub>2</sub> on air trapped in polar ice cores

2013 ◽  
Vol 6 (2) ◽  
pp. 251-262 ◽  
Author(s):  
B. Bereiter ◽  
T. F. Stocker ◽  
H. Fischer
Keyword(s):  
Vacuum Chamber ◽  
Ice Cores ◽  
Magnetic Bearings ◽  
Optimized Design ◽  
Polar Ice ◽  
Trapped Air ◽  
Ice Powder ◽  
Analytical System ◽  
Replicate Measurements ◽  
Current Systems

Abstract. For atmospheric CO2 reconstructions using ice cores, the technique to release the trapped air from the ice samples is essential for the precision and accuracy of the measurements. We present here a new dry extraction technique in combination with a new gas analytical system that together show significant improvements with respect to current systems. Ice samples (3–15 g) are pulverised using a novel centrifugal ice microtome (CIM) by shaving the ice in a cooled vacuum chamber (−27 °C) in which no friction occurs due to the use of magnetic bearings. Both, the shaving principle of the CIM and the use of magnetic bearings have not been applied so far in this field. Shaving the ice samples produces finer ice powder and releases a minimum of 90% of the trapped air compared to 50%–70% when needle crushing is employed. In addition, the friction-free motion with an optimized design to reduce contaminations of the inner surfaces of the device result in a reduced system offset of about 2.0 ppmv compared to 4.9 ppmv. The gas analytical part shows a higher precision than the corresponding part of our previous system by a factor of two, and all processes except the loading and cleaning of the CIM now run automatically. Compared to our previous system, the complete system shows a 3 times better measurement reproducibility of about 1.1 ppmv (1 σ) which is similar to the best reproducibility of other systems applied in this field. With this high reproducibility, no replicate measurements are required anymore for most future measurement campaigns resulting in a possible output of 12–20 measurements per day compared to a maximum of 6 with other systems.

scholarly journals A high-precision method for measurement of paleoatmospheric CO2 in small polar ice samples

2009 ◽  
Vol 55 (191) ◽  
pp. 499-506 ◽  
Author(s):  
Jinho Ahn ◽  
Edward J. Brook ◽  
Kate Howell
Keyword(s):  
High Precision ◽  
Ice Cores ◽  
Cold Trap ◽  
High Temporal Resolution ◽  
Mixing Ratio ◽  
Polar Ice ◽  
High Quality ◽  
Precision Method ◽  
Siple Dome ◽  
Replicate Measurements

AbstractWe describe a high-precision method, now in use in our laboratory, for measuring the CO2 mixing ratio of ancient air trapped in polar ice cores. Occluded air in ice samples weighing ∼8–15 g is liberated by crushing with steel pins at −35°C and trapped at −263°C in a cryogenic cold trap. CO2 in the extracted air is analyzed using gas chromatography. Replicate measurements for several samples of high-quality ice from the Siple Dome and Taylor Dome Antarctic ice cores have pooled standard deviations of <0.9 ppm. This high-precision technique is directly applicable to high-temporal-resolution studies for detection of small CO2 variations, for example CO2 variations of a few parts per million on millennial to decadal scales.

scholarly journals A review of the brittle ice zone in polar ice cores

2014 ◽  
Vol 55 (68) ◽  
pp. 72-82 ◽  
Author(s):  
Peter D. Neff
Keyword(s):  
Atmospheric Pressure ◽  
Accumulation Rate ◽  
Ice Core ◽  
Ice Cores ◽  
Snow Accumulation ◽  
Air Bubbles ◽  
Polar Ice ◽  
Overburden Pressure ◽  
Trapped Air ◽  
Borehole Temperatures

AbstractMaintaining ice-core quality through the brittle ice zone (BIZ) remains challenging for polar ice-core studies. At depth, increasing ice overburden pressurizes trapped air bubbles, causing fracture of cores upon exposure to atmospheric pressure. Fractured ice cores degrade analyses, reducing resolution and causing contamination. BIZ encounters at 18 sites across the Greenland, West and East Antarctic ice sheets are documented. The BIZ begins at a mean depth of 545 ± 162 m (1 standard deviation), extending to depths where ductile clathrate ice is reached: an average of 1132 ± 178 m depth. Ice ages in this zone vary with snow accumulation rate and ice thickness, beginning as young as 2 ka BP at Dye-3, Greenland, affecting ice >160 ka BP in age at Taylor Dome, Antarctica, and compromising up to 90% of retrieved samples at intermediate-depth sites. Effects of pressure and temperature on the BIZ are explored using modeled firn-column overburden pressure and borehole temperatures, revealing complex associations between firn densification and BIZ depth, and qualitatively supporting expected thinning of the BIZ at low ice temperatures due to shallower clathrate stability. Mitigating techniques for drilling, transport, sampling and analysis of brittle ice cores are also discussed.

scholarly journals CO2 measurements from polar ice cores: more data from different sites

Tellus B ◽  
1991 ◽  
Vol 43 (2) ◽  
pp. 91-96 ◽  
Author(s):  
Thomas Staffelbach ◽  
Bernhard Stauffer ◽  
Andreas Sigg ◽  
Hans Oeschger
Keyword(s):  
Ice Cores ◽  
Polar Ice

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

&lt;p&gt;The primary production, or oxygenic photosynthesis of the global biosphere, is one of the main source and sink of atmospheric oxygen (O&lt;sub&gt;2&lt;/sub&gt;) and carbon dioxide (CO&lt;sub&gt;2&lt;/sub&gt;), 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&lt;sub&gt;2&lt;/sub&gt; (&amp;#916;&lt;sup&gt;17&lt;/sup&gt;O of O&lt;sub&gt;2&lt;/sub&gt;) 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 &amp;#916;&lt;sup&gt;17&lt;/sup&gt;O of O&lt;sub&gt;2&lt;/sub&gt; 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&lt;sub&gt;2&lt;/sub&gt; were the pervasive feature of glacial periods over the last 800 ka, and (2) whether the global biosphere productivity during the &amp;#8220;lukewarm&amp;#8221; interglacials before the Mid-Brunhes Event (MBE) were lower than those after the MBE.&lt;br&gt;Here, we present an extended composite record of &amp;#916;&lt;sup&gt;17&lt;/sup&gt;O of O&lt;sub&gt;2&lt;/sub&gt; covering the last 800 ka, based on new &amp;#916;&lt;sup&gt;17&lt;/sup&gt;O of O&lt;sub&gt;2&lt;/sub&gt; 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&lt;sub&gt;2&lt;/sub&gt; 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.&lt;/p&gt;

scholarly journals Correction Of Air-content Measurements In Polar Ice For The Effect Of Cut Bubbles At The Surface Of The Sample

1990 ◽  
Vol 36 (124) ◽  
pp. 299-303 ◽  
Author(s):  
P. Martinerie ◽  
V.Ya. Lipenkov ◽  
D. Raynaud
Keyword(s):  
Finite Number ◽  
Theoretical Calculation ◽  
Ice Sheets ◽  
Ice Cores ◽  
Polar Ice ◽  
Density Data ◽  
Hydrostatic Method ◽  
Air Content ◽  
The Past ◽  
Statistical Noise

AbstractAir content (V) of polar ice has been used as an indicator of the past elevation of the ice sheets. A calculation is presented to correctVmeasurements performed on ice samples for the effect of cut bubbles at their surface. The results indicate a correction ranging from 1 to 10% for cubic ice samples with about 3 cm length. The correction depends mainly on the size of the bubbles. The theoretical calculation is experimentally verified. The statistical noise linked with the presence of a finite number of bubbles in the ice samples is evaluated. The influence of such a correction on theVprofiles measured on polar ice cores is discussed. The method in this paper can also be used for correction of ice-density data obtained by the hydrostatic method.

scholarly journals 10Be in Polar Ice and Atmospheres

1985 ◽  
Vol 7 ◽  
pp. 138-140 ◽  
Author(s):  
G.M. Raisbeck ◽  
F. Yiou
Keyword(s):  
Deposition Rate ◽  
Ice Cores ◽  
Polar Regions ◽  
High Latitudes ◽  
Accumulation Rates ◽  
Polar Ice ◽  
Polar Atmospheres ◽  
Stratospheric Aerosols

We briefly review the application of cosmogenic 10Be measurements in ice and polar atmospheres to: (i) the dating of ice cores, (ii) the deduction of past accumulation rates, (iii) information on the influx of stratospheric aerosols in polar regions, and the mechanism of incorporation of aerosols into the ice. We find that at high latitudes (&gt;74°), the 10Be deposition rate in the ice is more constant than the 10Be concentration.

scholarly journals An information-theoretic approach to extracting climate signals from deep polar ice cores

2019 ◽  
Vol 29 (10) ◽  
pp. 101105
Author(s):  
Joshua Garland ◽  
Tyler R. Jones ◽  
Michael Neuder ◽  
James W. C. White ◽  
Elizabeth Bradley
Keyword(s):  
Ice Cores ◽  
Theoretic Approach ◽  
Polar Ice ◽  
Information Theoretic ◽  
Climate Signals ◽  
Information Theoretic Approach
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