scholarly journals New methods for measuring atmospheric heavy noble gas isotope and elemental ratios in ice core samples

2018 ◽  
Vol 32 (10) ◽  
pp. 801-814 ◽  
Author(s):  
Bernhard Bereiter ◽  
Kenji Kawamura ◽  
Jeffrey P. Severinghaus
Keyword(s):  
Noble Gas ◽  
Ice Core ◽  
Elemental Ratios ◽  
Core Samples ◽  
New Methods ◽  
Noble Gas Isotope

scholarly journals The influence of layering and barometric pumping on firn air transport in a 2-D model

2018 ◽  
Vol 12 (6) ◽  
pp. 2021-2037 ◽  
Author(s):  
Benjamin Birner ◽  
Christo Buizert ◽  
Till J. W. Wagner ◽  
Jeffrey P. Severinghaus
Keyword(s):  
Dispersion Model ◽  
Noble Gas ◽  
Ice Core ◽  
Transport Processes ◽  
Air Transport ◽  
Atmospheric Composition ◽  
Elemental Ratios ◽  
Barometric Pumping ◽  
Kinetic Fractionation ◽  
D Model

Abstract. Ancient air trapped in ice core bubbles has been paramount to developing our understanding of past climate and atmospheric composition. Before air bubbles become isolated in ice, the atmospheric signal is altered in the firn column by transport processes such as advection and diffusion. However, the influence of low-permeability layers and barometric pumping (driven by surface pressure variability) on firn air transport is not well understood and is not readily captured in conventional one-dimensional (1-D) firn air models. Here we present a two-dimensional (2-D) trace gas advection–diffusion–dispersion model that accounts for discontinuous horizontal layers of reduced permeability. We find that layering or barometric pumping individually yields too small a reduction in gravitational settling to match observations. In contrast, when both effects are active, the model's gravitational fractionation is suppressed as observed. Layering focuses airflows in certain regions in the 2-D model, which acts to amplify the dispersive mixing resulting from barometric pumping. Hence, the representation of both factors is needed to obtain a realistic emergence of the lock-in zone. In contrast to expectations, we find that the addition of barometric pumping in the layered 2-D model does not substantially change the differential kinetic fractionation of fast- and slow-diffusing trace gases. Like 1-D models, the 2-D model substantially underestimates the amount of differential kinetic fractionation seen in actual observations, suggesting that further subgrid-scale processes may be missing in the current generation of firn air transport models. However, we find robust scaling relationships between kinetic isotope fractionation of different noble gas isotope and elemental ratios. These relationships may be used to correct for kinetic fractionation in future high-precision ice core studies and can amount to a bias of up to 0.45 °C in noble-gas-based mean ocean temperature reconstructions at WAIS Divide, Antarctica.

scholarly journals The influence of layering and barometric pumping on firn air transport in a 2D model

2017 ◽  
Author(s):  
Benjamin Birner ◽  
Christo Buizert ◽  
Till J. W. Wagner ◽  
Jeffrey P. Severinghaus
Keyword(s):  
Dispersion Model ◽  
Noble Gas ◽  
Ice Core ◽  
Transport Processes ◽  
Air Transport ◽  
Atmospheric Composition ◽  
Elemental Ratios ◽  
Barometric Pumping ◽  
Kinetic Fractionation ◽  
2D Model

Abstract. Ancient air trapped in ice core bubbles has been paramount to developing our understanding of past climate and atmospheric composition. Before air bubbles become isolated in ice, the atmospheric signal is altered in the firn column by transport processes such as advection and diffusion. However, the influence of impermeable layers and barometric pumping (driven by surface pressure variability) on firn air transport is not well understood and cannot be captured in conventional 1-dimensional firn air models. Here we present a 2-dimensional (2D) trace gas advection-diffusion-dispersion model that accounts for discontinuous horizontal layers of reduced permeability. We find that layering and barometric pumping individually yield too small a reduction in gravitational settling to match observations. In contrast, a combination of both effects more strongly suppresses gravitational fractionation. Layering locally focuses airflows in the 2D model and thus amplifies the dispersive mixing resulting from barometric pumping. Hence, the representation of both factors is needed to obtain a more natural emergence of the lock-in zone. Moreover, we find that barometric pumping in the layered 2D model does not substantially change the differential kinetic fractionation of fast and slow diffusing trace gases, which is observed in nature. This suggests that further subgrid-scale physics may be missing in the current generation of firn air transport models. However, we find robust scaling relationships between kinetic isotope fractionation of different noble gas isotope and elemental ratios. These relationships may be used to correct for kinetic fractionation in future high precision ice core studies.

Antarctic ice core samples: culturable bacterial diversity

2013 ◽  
Vol 164 (1) ◽  
pp. 70-82 ◽  
Author(s):  
Sisinthy Shivaji ◽  
Zareena Begum ◽  
Singireesu Soma Shiva Nageswara Rao ◽  
Puram V. Vishnu Vardhan Reddy ◽  
Poorna Manasa ◽  
...  
Keyword(s):  
Bacterial Diversity ◽  
Ice Core ◽  
Core Samples

New notions of Vikulovskaya series reservoir model in the area of Krasnoleninskoye field (Western Siberia)

2020 ◽  
pp. 66-74
Author(s):  
T. G. Isakova ◽  
T. F. Diakonova ◽  
A. D. Nosikova ◽  
D. S. Savchenko ◽  
N. I. Korobova ◽  
...  
Keyword(s):  
Western Siberia ◽  
Parameters Estimation ◽  
Well Logs ◽  
Reservoir Model ◽  
New Model ◽  
Core Samples ◽  
New Methods

Detailed lithological, sedimentological, petrophysical studies of columns and core samples of Vikulovskaya series were performed. On the basis of researches the new model of a reservoir was made and new methods of volumetric parameters estimation based on well logs were established.

scholarly journals An automated GC-C-GC-IRMS setup to measure palaeoatmospheric δ<sup>13</sup>C-CH<sub>4</sub>, δ<sup>15</sup>N-N<sub>2</sub>O and δ<sup>18</sup>O-N<sub>2</sub>O in one ice core sample

2013 ◽  
Vol 6 (8) ◽  
pp. 2027-2041 ◽  
Author(s):  
P. Sperlich ◽  
C. Buizert ◽  
T. M. Jenk ◽  
C. J. Sapart ◽  
M. Prokopiou ◽  
...  
Keyword(s):  
Ice Core ◽  
Gold Catalyst ◽  
Isotope Ratios ◽  
Core Sample ◽  
Ion Source ◽  
Resolving Power ◽  
Published Data ◽  
Core Samples ◽  
Stable Conditions ◽  
Ch4 And N2o

Abstract. Air bubbles in ice core samples represent the only opportunity to study the mixing ratio and isotopic variability of palaeoatmospheric CH4 and N2O. The highest possible precision in isotope measurements is required to maximize the resolving power for CH4 and N2O sink and source reconstructions. We present a new setup to measure δ13C-CH4, δ15N-N2O and δ18O-N2O isotope ratios in one ice core sample and with one single IRMS instrument, with a precision of 0.09, 0.6 and 0.7‰, respectively, as determined on 0.6–1.6 nmol CH4 and 0.25–0.6 nmol N2O. The isotope ratios are referenced to the VPDB scale (δ13C-CH4), the N2-air scale (δ15N-N2O) and the VSMOW scale (δ18O-N2O). Ice core samples of 200–500 g are melted while the air is constantly extracted to minimize gas dissolution. A helium carrier gas flow transports the sample through the analytical system. We introduce a new gold catalyst to oxidize CO to CO2 in the air sample. CH4 and N2O are then separated from N2, O2, Ar and CO2 before they get pre-concentrated and separated by gas chromatography. A combustion unit is required for δ13C-CH4 analysis, which is equipped with a constant oxygen supply as well as a post-combustion trap and a post-combustion GC column (GC-C-GC-IRMS). The post-combustion trap and the second GC column in the GC-C-GC-IRMS combination prevent Kr and N2O interferences during the isotopic analysis of CH4-derived CO2. These steps increase the time for δ13C-CH4 measurements, which is used to measure δ15N-N2O and δ18O-N2O first and then δ13C-CH4. The analytical time is adjusted to ensure stable conditions in the ion source before each sample gas enters the IRMS, thereby improving the precision achieved for measurements of CH4 and N2O on the same IRMS. The precision of our measurements is comparable to or better than that of recently published systems. Our setup is calibrated by analysing multiple reference gases that were injected over bubble-free ice samples. We show that our measurements of δ13C-CH4 in ice core samples are generally in good agreement with previously published data after the latter have been corrected for krypton interferences.

scholarly journals Concept and Testing of a Remotely Operated Vehicle-Mountable Inductive Electrothermal Polar Under-Ice Corer

2017 ◽  
Vol 51 (6) ◽  
pp. 33-43 ◽  
Author(s):  
Narayanaswamy Vedachalam ◽  
Arumugam Vadivelan ◽  
Arunachalam Umapathy ◽  
Munusamy Murugesan ◽  
Gopal Durai ◽  
...  
Keyword(s):  
Ice Core ◽  
Input Power ◽  
Design Development ◽  
Polar Ice ◽  
Remotely Operated Vehicle ◽  
Element Analysis ◽  
Ice Shelves ◽  
Core Samples ◽  
Inner Diameter ◽  
Aided Design

AbstractIce core samples from the polar ice shelves contain valuable paleo-climatic records and information for understanding the unique polar under-ice ecosystem. This paper describes the finite element analysis-aided design, development, and qualification of a 63-mm-inner diameter, 250-mm-long variable power underwater remotely operated vehicle-mountable inductive ice corer (IIC) for collecting ice core samples beneath the polar ice shelves. It is determined that, with the IIC operating with an input power of 1,000 W at 30 kHz, it is possible to have an ice penetration rate of 14 mm/min and obtain an ice core of 51 mm in diameter. The experimental results are found to comply with the numerical model with an accuracy of 95%.

scholarly journals The Community Firn Model (CFM) v1.0

2020 ◽  
Author(s):  
C. Max Stevens ◽  
Vincent Verjans ◽  
Jessica M.D. Lundin ◽  
Emma C. Kahle ◽  
Annika N. Horlings ◽  
...  
Keyword(s):  
Climate Model ◽  
Noble Gas ◽  
Regional Climate ◽  
Ice Core ◽  
Ice Cores ◽  
Elevation Change ◽  
Model Framework ◽  
Modular Model ◽  
Surface Elevation Change ◽  
Air Diffusion

Abstract. Models that simulate evolution of polar firn are important for several applications in glaciology, including converting ice-sheet elevation-change measurements to mass change and interpreting climate records in ice cores. We have developed the Community Firn Model (CFM), an open-source, modular model framework designed to simulate numerous physical processes in firn. The modules include firn densification, heat transport, meltwater percolation and refreezing, water-isotope diffusion, and firn-air diffusion. The CFM is designed so that new modules can be added with ease. In this paper, we first describe the CFM and its modules. We then demonstrate the CFM's usefulness in two model applications that utilize two of its novel aspects. The CFM currently has the ability to run any of 13 previously published firn-densification models, and in the first application we compare those models' results when they are forced with regional climate model outputs for Summit, Greenland. The results show that the models do not agree well (spread greater than 10 %) when predicting depth-integrated porosity, firn age, or trend in surface-elevation change trend. In the second application, we show that the CFM's coupled firn-air and firn-densification models can simulate noble-gas records from an ice core better than a firn-air model alone.

Constraining ice core chronologies with 39Ar and 81Kr

2021 ◽  
Author(s):  
Florian Ritterbusch ◽  
Jinho Ahn ◽  
Ji-Qiang Gu ◽  
Wei Jiang ◽  
Giyoon Lee ◽  
...  
Keyword(s):  
Sample Size ◽  
Half Life ◽  
Earth Science ◽  
Noble Gas ◽  
Ice Core ◽  
Ice Cores ◽  
High Mountain ◽  
National Academy Of Sciences ◽  
Geophysical Research ◽  
Mountain Glaciers

&lt;p&gt;Paleoclimate reconstructions from ice core records can be hampered due to the lack of a reliable chronology, especially when the stratigraphy is disturbed and conventional dating methods cannot be readily applied. The noble-gas radioisotopes &lt;sup&gt;81&lt;/sup&gt;Kr and &lt;sup&gt;39&lt;/sup&gt;Ar can in these cases provide robust constraints as they yield absolute, radiometric ages. &lt;sup&gt;81&lt;/sup&gt;Kr (half-life 229 ka) covers the time span of 50-1300 ka, which is particularly relevant for polar ice cores, whereas &lt;sup&gt;39&lt;/sup&gt;Ar (half-life 269 a) with a dating range of 50-1800 a is suitable for high mountain glaciers. For a long time the use of &lt;sup&gt;81&lt;/sup&gt;Kr and &lt;sup&gt;39&lt;/sup&gt;Ar for dating of ice samples was hampered by the lack of a detection technique that can meet its extremely small abundance at a reasonable sample size.&lt;/p&gt;&lt;p&gt;Here, we present &lt;sup&gt;81&lt;/sup&gt;Kr and &lt;sup&gt;39&lt;/sup&gt;Ar dating of Antarctic and Tibetan ice cores with the detection method Atom Trap Trace Analysis (ATTA), using 5-10 kg of ice for &lt;sup&gt;81&lt;/sup&gt;Kr and 2-5 kg for &lt;sup&gt;39&lt;/sup&gt;Ar. Recent advances in further decreasing the sample size and increasing the dating precision will be discussed. Current studies include &lt;sup&gt;81&lt;/sup&gt;Kr dating in shallow ice cores from the Larsen Blue ice area, East Antarctica, in order to retrieve climate signals from the last glacial termination. Moreover, an &lt;sup&gt;39&lt;/sup&gt;Ar profile from a central Tibetan ice core has been obtained in combination with layer counting based on isotopic and visual stratigraphic signals. The presented studies demonstrate how &lt;sup&gt;81&lt;/sup&gt;Kr and &lt;sup&gt;39&lt;/sup&gt;Ar can constrain the age range of ice cores and complement other methods in developing an ice core chronology.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;[1] Z.-T. Lu, Tracer applications of noble gas radionuclides in the geosciences, Earth-Science Reviews 138, 196-214, (2014)&lt;br&gt;[2] C. Buizert, Radiometric &lt;sup&gt;81&lt;/sup&gt;Kr dating identifies 120,000-year-old ice at Taylor Glacier, Antarctica, Proceedings of the National Academy of Sciences, &lt;strong&gt;111&lt;/strong&gt;, 6876, (2014)&lt;/p&gt;&lt;p&gt;[3] L. Tian, &lt;sup&gt;81&lt;/sup&gt;Kr Dating at the Guliya Ice Cap, Tibetan Plateau, Geophysical Research Letters, (2019)&lt;/p&gt;&lt;p&gt;http://atta.ustc.edu.cn&lt;/p&gt;

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