scholarly journals High-precision dual-inlet IRMS measurements of the stable isotopes of CO<sub>2</sub> and the N<sub>2</sub>O / CO<sub>2</sub> ratio from polar ice core samples

2014 ◽  
Vol 7 (11) ◽  
pp. 3825-3837 ◽  
Author(s):  
T. K. Bauska ◽  
E. J. Brook ◽  
A. C. Mix ◽  
A. Ross
Keyword(s):  
Isotopic Composition ◽  
High Precision ◽  
Water Vapor Pressure ◽  
Ice Core ◽  
Ice Cores ◽  
Mass Spectrometric Method ◽  
Polar Ice ◽  
Mixing Ratios ◽  
Core Samples ◽  
Oxygen Isotopic

Abstract. An important constraint on mechanisms of past carbon cycle variability is provided by the stable isotopic composition of carbon in atmospheric carbon dioxide (δ13C-CO2) trapped in polar ice cores, but obtaining very precise measurements has proven to be a significant analytical challenge. Here we describe a new technique to determine the δ13C of CO2 at very high precision, as well as measuring the CO2 and N2O mixing ratios. In this method, ancient air is extracted from relatively large ice samples (~400 g) with a dry-extraction "ice grater" device. The liberated air is cryogenically purified to a CO2 and N2O mixture and analyzed with a microvolume-equipped dual-inlet IRMS (Thermo MAT 253). The reproducibility of the method, based on replicate analysis of ice core samples, is 0.02‰ for δ13C-CO2 and 2 ppm and 4 ppb for the CO2 and N2O mixing ratios, respectively (1σ pooled standard deviation). Our experiments show that minimizing water vapor pressure in the extraction vessel by housing the grating apparatus in a ultralow-temperature freezer (−60 °C) improves the precision and decreases the experimental blank of the method to −0.07 ± 0.04‰. We describe techniques for accurate calibration of small samples and the application of a mass-spectrometric method based on source fragmentation for reconstructing the N2O history of the atmosphere. The oxygen isotopic composition of CO2 is also investigated, confirming previous observations of oxygen exchange between gaseous CO2 and solid H2O within the ice archive. These data offer a possible constraint on oxygen isotopic fractionation during H2O and CO2 exchange below the H2O bulk melting temperature.

scholarly journals High precision dual-inlet IRMS measurements of the stable isotopes of CO<sub>2</sub> and the N<sub>2</sub>O/CO<sub>2</sub> ratio from polar ice core samples

2014 ◽  
Vol 7 (7) ◽  
pp. 6529-6564 ◽  
Author(s):  
T. K. Bauska ◽  
E. J. Brook ◽  
A. C. Mix ◽  
A. Ross
Keyword(s):  
Isotopic Composition ◽  
Water Vapor Pressure ◽  
Ice Core ◽  
Ice Cores ◽  
Spectrometric Method ◽  
Mass Spectrometric Method ◽  
Polar Ice ◽  
Mixing Ratios ◽  
Core Samples ◽  
Oxygen Isotopic

Abstract. An important constraint on mechanisms of past carbon cycle variability is provided by the stable isotopic composition of carbon in atmospheric carbon dioxide (δ13C-CO2) trapped in polar ice cores, but obtaining very precise measurements has proven to be a significant analytical challenge. Here we describe a new technique to determine the δ13C of CO2 at exceptional precision, as well as measuring the CO2 and N2O mixing ratios. In this method, ancient air is extracted from relatively large ice samples (~ 400 grams) with a dry-extraction "ice-grater" device. The liberated air is cryogenically purified to a CO2 and N2O mixture and analyzed with a micro-volume equipped dual-inlet IRMS (Thermo MAT 253). The reproducibility of the method, based on replicate analysis of ice core samples, is 0.02‰ for δ13C-CO2 and 2 ppm and 4 ppb for the CO2 and N2O mixing ratios, respectively (1-sigma pooled standard deviation). Our experiments show that minimizing water vapor pressure in the extraction vessel by housing the grating apparatus in a ultra-low temperature freezer (−60 °C) improves the precision and decreases the experimental blank of the method. We describe techniques for accurate calibration of small samples and the application of a mass spectrometric method based on source fragmentation for reconstructing the N2O history of the atmosphere. The oxygen isotopic composition of CO2 is also investigated, confirming previous observations of oxygen exchange between gaseous CO2 and solid H2O within the ice archive. These data offer a possible constraint on oxygen isotopic fractionation during H2O and CO2 exchange below the H2O bulk melting temperature.

scholarly journals Post-coring entrapment of modern air in polar ice cores collected near the firn-ice transition: evidence from CFC-12 measurements in Antarctic firn air and shallow ice cores

2010 ◽  
Vol 10 (1) ◽  
pp. 1631-1657 ◽  
Author(s):  
M. Aydin ◽  
S. A. Montzka ◽  
M. O. Battle ◽  
M. B. Williams ◽  
W. De Bruyn ◽  
...  
Keyword(s):  
Ice Core ◽  
Ice Cores ◽  
Trace Gas ◽  
Gas Composition ◽  
Physical Processes ◽  
Polar Ice ◽  
Air Samples ◽  
Mixing Ratios ◽  
Core Samples ◽  
History Of

Abstract. In this study, we report the first measurements of CFC-12 (CCl2F2) in air extracted from shallow ice cores along with firn air CFC-12 measurements from three Antarctic sites. The firn air data are consistent with the known atmospheric history of CFC-12. In contrast, the ice core samples collected near the firn-ice transition exhibit anomalously high CFC-12 levels. Together, the ice core and firn air data provide evidence for presence of modern air entrapped in shallow ice core samples. We propose that this is due to closure of open pores after drilling, entrapping modern air and resulting in elevated CFC-12 mixing ratios. Our measurements reveal the presence of open porosity below the depth at which firn air samples can be collected and demonstrate how the composition of bubble air in shallow ice cores can be altered during the post-drilling period through purely physical processes. These results have implications for investigations involving trace gas composition of bubbles in shallow ice cores.

scholarly journals EBSD analysis of subgrain boundaries and dislocation slip systems in Antarctic and Greenland ice

Solid Earth ◽  
2017 ◽  
Vol 8 (5) ◽  
pp. 883-898 ◽  
Author(s):  
Ilka Weikusat ◽  
Ernst-Jan N. Kuiper ◽  
Gill M. Pennock ◽  
Sepp Kipfstuhl ◽  
Martyn R. Drury
Keyword(s):  
Basal Slip ◽  
Plastic Anisotropy ◽  
Ice Core ◽  
Ice Cores ◽  
Dislocation Slip ◽  
Slip Systems ◽  
Polar Ice ◽  
Electron Backscattered Diffraction ◽  
Depth Level ◽  
Core Samples

Abstract. Ice has a very high plastic anisotropy with easy dislocation glide on basal planes, while glide on non-basal planes is much harder. Basal glide involves dislocations with the Burgers vector b = 〈a〉, while glide on non-basal planes can involve dislocations with b = 〈a〉, b = [c], and b = 〈c + a〉. During the natural ductile flow of polar ice sheets, most of the deformation is expected to occur by basal slip accommodated by other processes, including non-basal slip and grain boundary processes. However, the importance of different accommodating processes is controversial. The recent application of micro-diffraction analysis methods to ice, such as X-ray Laue diffraction and electron backscattered diffraction (EBSD), has demonstrated that subgrain boundaries indicative of non-basal slip are present in naturally deformed ice, although so far the available data sets are limited. In this study we present an analysis of a large number of subgrain boundaries in ice core samples from one depth level from two deep ice cores from Antarctica (EPICA-DML deep ice core at 656 m of depth) and Greenland (NEEM deep ice core at 719 m of depth). EBSD provides information for the characterization of subgrain boundary types and on the dislocations that are likely to be present along the boundary. EBSD analyses, in combination with light microscopy measurements, are presented and interpreted in terms of the dislocation slip systems. The most common subgrain boundaries are indicative of basal 〈a〉 slip with an almost equal occurrence of subgrain boundaries indicative of prism [c] or 〈c + a〉 slip on prism and/or pyramidal planes. A few subgrain boundaries are indicative of prism 〈a〉 slip or slip of 〈a〉 screw dislocations on the basal plane. In addition to these classical polygonization processes that involve the recovery of dislocations into boundaries, alternative mechanisms are discussed for the formation of subgrain boundaries that are not related to the crystallography of the host grain.The finding that subgrain boundaries indicative of non-basal slip are as frequent as those indicating basal slip is surprising. Our evidence of frequent non-basal slip in naturally deformed polar ice core samples has important implications for discussions on ice about plasticity descriptions, rate-controlling processes which accommodate basal glide, and anisotropic ice flow descriptions of large ice masses with the wider perspective of sea level evolution.

scholarly journals An improved method for delta <sup>15</sup>N measurements in ice cores

2008 ◽  
Vol 4 (1) ◽  
pp. 149-171 ◽  
Author(s):  
F. S. Mani ◽  
P. Dennis ◽  
W. T. Sturges ◽  
R. Mulvaney ◽  
M. Leuenberger
Keyword(s):  
High Precision ◽  
Climate Changes ◽  
Ice Core ◽  
Ice Cores ◽  
Atmospheric Nitrogen ◽  
Nitrogen Gas ◽  
Last Glacial Period ◽  
Temperature Changes ◽  
Core Samples ◽  
The Last Glacial

Abstract. The use of isotopic ratios of nitrogen gas (δ15N) trapped in ice cores as a paleothermometer to characterise abrupt climate changes is becoming a widespread technique. The versatility of the technique could be enhanced, for instance in quantifying small temperature changes during the last glacial period in Antarctic ice cores, by using high precision methods. In this paper, we outline a method for measuring δ15N to a precision of 0.006\\permil (1σ, n=9) from replicate ice core samples. The high precision results from removing oxygen, carbon dioxide and water vapour from the air extracted from ice cores. The advantage of the technique is that it does not involve correction for isobaric interference due to CO+ ions. We also highlight the importance of oxygen removal from the sample, and how it influences δ15N measurements. The results show that a small amount of oxygen in the sample can be detrimental to achieving an optimum precision in δ15N measurements of atmospheric nitrogen trapped ice core samples.

scholarly journals A sublimation technique for high-precision measurements of δ<sup>13</sup>CO<sub>2</sub> and mixing ratios of CO<sub>2</sub> and N<sub>2</sub>O from air trapped in ice cores

2011 ◽  
Vol 4 (2) ◽  
pp. 1853-1892 ◽  
Author(s):  
J. Schmitt ◽  
R. Schneider ◽  
H. Fischer
Keyword(s):  
High Precision ◽  
Ice Core ◽  
Stable Carbon Isotope ◽  
Ice Cores ◽  
Glass Tube ◽  
Isotope Ratio Mass Spectrometry ◽  
Vacuum Sublimation ◽  
Mixing Ratios ◽  
Trapped Air ◽  
Organic Sample

Abstract. In order to provide high precision stable carbon isotope ratios (δ13CO2 or δ13C on CO2) from small bubble and clathrate ice core samples we developed a new method based on vacuum sublimation extraction of the CO2 and gas chromatography-isotope ratio mass spectrometry (GC-IRMS). In a first step the trapped air is quantitatively released from ~30 g of ice and CO2 together with N2O are separated from the bulk air components and stored in a miniature glass tube. In an off-line step, the extracted sample is introduced into a helium carrier flow using a minimised tube cracker device. Prior to measurement, N2O and organic sample contaminants are gas chromatographically separated from CO2. Pulses of a CO2/N2O mixture are admitted to the tube cracker and follow the path of the sample through the system. This allows an identical treatment and comparison of sample and standard peaks. The ability of the method to reproduce δ13C from bubble and clathrate ice is verified on different ice cores. We achieve reproducibilities for bubble ice between 0.05‰ and 0.07‰ and for clathrate ice between 0.05‰ and 0.09‰ (dependent on the ice core used). A comparison of our data with measurements on bubble ice from the same ice core but using a mechanic extraction device shows no significant systematic offset. In addition to δ13C, the CO2 and N2O mixing ratios can be volumetrically derived with a precision of 2 ppmv and 8 ppbv, respectively.

scholarly journals A sublimation technique for high-precision measurements of δ<sup>13</sup>CO<sub>2</sub> and mixing ratios of CO<sub>2</sub> and N<sub>2</sub>O from air trapped in ice cores

2011 ◽  
Vol 4 (7) ◽  
pp. 1445-1461 ◽  
Author(s):  
J. Schmitt ◽  
R. Schneider ◽  
H. Fischer
Keyword(s):  
High Precision ◽  
Ice Core ◽  
Stable Carbon Isotope ◽  
Ice Cores ◽  
Glass Tube ◽  
Isotope Ratio Mass Spectrometry ◽  
Mixing Ratios ◽  
Trapped Air ◽  
Organic Sample ◽  
Mechanical Extraction

Abstract. In order to provide high precision stable carbon isotope ratios (δ13CO2 or δ13C of CO2) from small bubbly, partially and fully clathrated ice core samples we developed a new method based on sublimation coupled to gas chromatography-isotope ratio mass spectrometry (GC-IRMS). In a first step the trapped air is quantitatively released from ~30 g of ice and CO2 together with N2O are separated from the bulk air components and stored in a miniature glass tube. In an off-line step, the extracted sample is introduced into a helium carrier flow using a minimised tube cracker device. Prior to measurement, N2O and organic sample contaminants are gas chromatographically separated from CO2. Pulses of a CO2/N2O mixture are admitted to the tube cracker and follow the path of the sample through the system. This allows an identical treatment and comparison of sample and standard peaks. The ability of the method to reproduce δ13C from bubble and clathrate ice is verified on different ice cores. We achieve reproducibilities for bubble ice between 0.05 ‰ and 0.07 ‰ and for clathrate ice between 0.05 ‰ and 0.09 ‰ (dependent on the ice core used). A comparison of our data with measurements on bubble ice from the same ice core but using a mechanical extraction device shows no significant systematic offset. In addition to δ13C, the CO2 and N2O mixing ratios can be volumetrically derived with a precision of 2 ppmv and 8 ppbv, respectively.

scholarly journals A method for analysis of vanillic acid in polar ice cores

2015 ◽  
Vol 11 (2) ◽  
pp. 227-232 ◽  
Author(s):  
M. M. Grieman ◽  
J. Greaves ◽  
E. S. Saltzman
Keyword(s):  
Biomass Burning ◽  
Vanillic Acid ◽  
Ice Core ◽  
Ice Cores ◽  
Reversed Phase ◽  
Polar Ice ◽  
Core Samples ◽  
Wide Range ◽  
Polar Ice Sheets ◽  
Arctic Ice

Abstract. Biomass burning generates a wide range of organic compounds that are transported via aerosols to the polar ice sheets. Vanillic acid is a product of conifer lignin combustion, which has previously been observed in laboratory and ambient biomass burning aerosols. In this study a method was developed for analysis of vanillic acid in melted polar ice core samples. Vanillic acid was chromatographically separated using reversed-phase liquid chromatography (HPLC) and detected using electrospray ionization–triple quadrupole mass spectrometry (ESI-MS/MS). Using a 100 μL injection loop and analysis time of 4 min, we obtained a detection limit of 77 ppt (parts per trillion by mass) and an analytical precision of ±10%. Measurements of vanillic acid in Arctic ice core samples from the Siberian Akademii Nauk core are shown as an example application of the method.

scholarly journals Post-coring entrapment of modern air in some shallow ice cores collected near the firn-ice transition: evidence from CFC-12 measurements in Antarctic firn air and ice cores

2010 ◽  
Vol 10 (11) ◽  
pp. 5135-5144 ◽  
Author(s):  
M. Aydin ◽  
S. A. Montzka ◽  
M. O. Battle ◽  
M. B. Williams ◽  
W. J. De Bruyn ◽  
...  
Keyword(s):  
Ice Core ◽  
Ice Cores ◽  
Trace Gas ◽  
Gas Composition ◽  
Accumulation Rates ◽  
Physical Processes ◽  
Air Samples ◽  
Mixing Ratios ◽  
Core Samples ◽  
History Of

Abstract. In this study, we report measurements of CFC-12 (CCl2F2) in firn air and in air extracted from shallow ice cores from three Antarctic sites. The firn air data are consistent with the known atmospheric history of CFC-12. In contrast, some of the ice core samples collected near the firn-ice transition exhibit anomalously high CFC-12 levels. Together, the ice core and firn air data provide evidence for the presence of modern air entrapped in the shallow ice core samples that likely contained open pores at the time of collection. We propose that this is due to closure of the open pores after drilling, entrapping modern air and resulting in elevated CFC-12 mixing ratios. Our results reveal that open porosity can exist below the maximum depth at which firn air samples can be collected, particularly at sites with lower accumulation rates. CFC-12 measurements demonstrate that post-drilling closure of open pores can lead to a change in the composition of bubble air in shallow ice cores through purely physical processes. The results have implications for investigations involving trace gas composition of bubbles in shallow ice cores collected near the firn-ice transition.

scholarly journals A method for analysis of vanillic acid in polar ice cores

2014 ◽  
Vol 10 (4) ◽  
pp. 2805-2820 ◽  
Author(s):  
M. M. Grieman ◽  
J. Greaves ◽  
E. S. Saltzman
Keyword(s):  
Biomass Burning ◽  
Vanillic Acid ◽  
Ice Core ◽  
Ice Cores ◽  
Reversed Phase ◽  
Polar Ice ◽  
Core Samples ◽  
Wide Range ◽  
Polar Ice Sheets ◽  
Arctic Ice

Abstract. Biomass burning generates a wide range of organic compounds that are transported via aerosols to the polar ice sheets. Vanillic acid is a product of conifer lignin combustion, which has previously been observed in laboratory and ambient biomass burning aerosols. In this study a method was developed for analysis of vanillic acid in melted polar ice core samples. Vanillic acid was chromatographically separated using reversed phase LC and detected using electrospray triple quadrupole mass spectrometry (ESI-MS/MS). Using a 100 μL injection loop and analysis time of 4 min, we obtained a detection limit (S : N = 2) of 58 ppt (parts per trillion by mass) and an analytical precision of ±10 %. Measurements of vanillic acid in Arctic ice core samples from the Siberian Akademii Nauk core are shown as an example application of the method.

scholarly journals A new CF-IRMS system for quantifying stable isotopes of carbon monoxide from ice cores and small air samples

2010 ◽  
Vol 3 (5) ◽  
pp. 1307-1317 ◽  
Author(s):  
Z. Wang ◽  
J. E. Mak
Keyword(s):  
Carbon Monoxide ◽  
Stable Isotopes ◽  
Ice Core ◽  
Isotope Analysis ◽  
Ice Cores ◽  
Isotope Ratio Mass Spectrometry ◽  
Vacuum Extraction ◽  
Air Samples ◽  
Mixing Ratios ◽  
Core Samples

Abstract. We present a new analysis technique for stable isotope ratios (δ13C and δ18O) of atmospheric carbon monoxide (CO) from ice core samples. The technique is an online cryogenic vacuum extraction followed by continuous-flow isotope ratio mass spectrometry (CF-IRMS); it can also be used with small air samples. The CO extraction system includes two multi-loop cryogenic cleanup traps, a chemical oxidant for oxidation to CO2, a cryogenic collection trap, a cryofocusing unit, gas chromatography purification, and subsequent injection into a Finnigan Delta Plus IRMS. Analytical precision of 0.2‰ (±1δ) for δ13C and 0.6‰ (±1δ) for δ18O can be obtained for 100 mL (STP) air samples with CO mixing ratios ranging from 60 ppbv to 140 ppbv (~268–625 pmol CO). Six South Pole ice core samples from depths ranging from 133 m to 177 m were processed for CO isotope analysis after wet extraction. To our knowledge, this is the first measurement of stable isotopes of CO in ice core air.

Sign in / Sign up

Export Citation Format

Share Document