scholarly journals The Influence On Atmospheric Composition of Volcanic Eruptions as Derived From Ice-Core Analysis

1985 ◽  
Vol 7 ◽  
pp. 125-129 ◽  
Author(s):  
C.U. Hammer
Keyword(s):  
Ice Core ◽  
Ice Sheets ◽  
Ice Cores ◽  
Volcanic Eruptions ◽  
Atmospheric Composition ◽  
Core Analysis ◽  
Polar Ice ◽  
Ice Caps ◽  
The Past ◽  
Polar Ice Sheets

Polar ice cores offer datable past snow deposits in the form of annual ice layers, which reflect the past atmospheric composition. Trace substances in the cores are related to the past mid-tropospheric impurity load, this being due to the vast extent of the polar ice sheets (or ice caps), their surface elevations and remoteness from most aerosol sources. Volcanic eruptions add to the rather low background impurity load via their eruptive products. This paper concentrates on the widespread influence on atmospheric impurity loads caused by the acid gas products from volcanic eruptions. In particular the following subjects are discussed: acid volcanic signals in ice cores, latitude of eruptions as derived by ice-core analysis, inter-hemispheric dating of the two polar ice sheets by equatorial eruptions, volcanic deposits in ice cores during the last glacial period and climatic implications.

scholarly journals The Influence On Atmospheric Composition of Volcanic Eruptions as Derived From Ice-Core Analysis

1985 ◽  
Vol 7 ◽  
pp. 125-129 ◽  
Author(s):  
C.U. Hammer
Keyword(s):  
Ice Core ◽  
Ice Sheets ◽  
Ice Cores ◽  
Volcanic Eruptions ◽  
Atmospheric Composition ◽  
Core Analysis ◽  
Polar Ice ◽  
Ice Caps ◽  
The Past ◽  
Polar Ice Sheets

Polar ice cores offer datable past snow deposits in the form of annual ice layers, which reflect the past atmospheric composition. Trace substances in the cores are related to the past mid-tropospheric impurity load, this being due to the vast extent of the polar ice sheets (or ice caps), their surface elevations and remoteness from most aerosol sources. Volcanic eruptions add to the rather low background impurity load via their eruptive products. This paper concentrates on the widespread influence on atmospheric impurity loads caused by the acid gas products from volcanic eruptions. In particular the following subjects are discussed: acid volcanic signals in ice cores, latitude of eruptions as derived by ice-core analysis, inter-hemispheric dating of the two polar ice sheets by equatorial eruptions, volcanic deposits in ice cores during the last glacial period and climatic implications.

scholarly journals Application of AMS 14C Dating to Ice Core Research

Radiocarbon ◽  
1995 ◽  
Vol 37 (2) ◽  
pp. 637-641 ◽  
Author(s):  
A T. Wilson
Keyword(s):  
Ice Core ◽  
Ice Sheets ◽  
Ice Cores ◽  
Unexpected Result ◽  
Polar Ice ◽  
14C Dating ◽  
The Past ◽  
Accelerator Mass Spectrometer ◽  
Polar Ice Sheets ◽  
Ams 14C Dating

I describe here the use of the accelerator mass spectrometer (AMS) sublimation technique to 14C-date polar ice cores. An unexpected result of this work has been to extend the understanding of how polar ice sheets entrap and record the past composition of the Earth's atmosphere. This work has led to the discovery of a new phenomenon in which CO2 and other greenhouse gases can be entrapped in cold (never melted) polar ice sheets.

scholarly journals Post-drilling recrystallization of the Byrd Station deep ice core and its relevance to current and future deep-core drilling on polar ice sheets

1994 ◽  
Vol 20 ◽  
pp. 231-236
Author(s):  
A.J. Gow
Keyword(s):  
Ice Core ◽  
Ice Sheets ◽  
Ice Cores ◽  
The United States ◽  
Polar Ice ◽  
Thin Sections ◽  
Full Extent ◽  
Drill Site ◽  
Polar Ice Sheets ◽  
Highly Strained

Cores of highly strained ice recovered from depths of 1200–1800 m at Byrd Station in 1967–68 have been found to have recrystallized while in storage in the United States. Such recrystallization, inferred to have occurred when temperatures in the storage facility rose above about – 14°C, would not have been discovered if thin sections of the cores had not been prepared and photographed at the drill site within hours of pulling the cores to the surface. It was only after new sections of the long stored cores were compared with the original sections that the full extent of recrystallization was revealed. The recrystallized structure emulates in both texture and fabric those observed in naturally annealed ice in the bottom 350 m at Byrd Station. It is concluded that polar ice cores should be stored at temperatures of –20°C or colder in order to inhibit or minimize post-drilling recrystallization.

scholarly journals A Review of the Microstructural Location of Impurities in Polar Ice and Their Impacts on Deformation

2021 ◽  
Vol 8 ◽  
Author(s):  
Nicolas Stoll ◽  
Jan Eichler ◽  
Maria Hörhold ◽  
Wataru Shigeyama ◽  
Ilka Weikusat
Keyword(s):  
Deformation Behaviour ◽  
Ice Core ◽  
Measurement Techniques ◽  
Ice Sheets ◽  
Ice Cores ◽  
Holistic Approach ◽  
Triple Junctions ◽  
Polar Ice ◽  
Theoretical Approaches ◽  
Polar Ice Sheets

Insoluble and soluble impurities, enclosed in polar ice sheets, have a major impact on the deformation behaviour of the ice. Macro- and Micro-scale deformation observed in ice sheets and ice cores has been retraced to chemical loads in the ice, even though the absolute concentration is negligible. And therefore the exact location of the impurities matters: Allocating impurities to specific locations inside the ice microstructure inherently determines the physical explanation of the observed interaction between chemical load and the deformational behaviour. Both, soluble and non-soluble impurities were located in grain boundaries, triple junctions or in the grain interior, using different methods, samples and theoretical approaches. While each of the observations is adding to the growing understanding of the effect of impurities in polar ice, the growing number of ambiguous results calls for a dedicated and holistic approach in assessing the findings. Thus, we here aim to give a state of the art overview of the development in microstructural impurity research over the last 20 years. We evaluate the used methods, discuss proposed deformation mechanisms and identify two main reasons for the observed ambiguity: 1) limitations and biases of measurement techniques and 2) the physical state of the analysed impurity. To overcome these obstacles we suggest possible approaches, such as the continuous analysis of impurities in deep ice cores with complementary methods, the implementation of these analyses into established in-situ ice core processing routines, a more holistic analysis of the microstructural location of impurities, and an enhanced knowledge-transfer via an open access data base.

scholarly journals Post-drilling recrystallization of the Byrd Station deep ice core and its relevance to current and future deep-core drilling on polar ice sheets

1994 ◽  
Vol 20 ◽  
pp. 231-236 ◽  
Author(s):  
A.J. Gow
Keyword(s):  
Ice Core ◽  
Ice Sheets ◽  
Ice Cores ◽  
The United States ◽  
Polar Ice ◽  
Thin Sections ◽  
Full Extent ◽  
Drill Site ◽  
Polar Ice Sheets ◽  
Highly Strained

Cores of highly strained ice recovered from depths of 1200–1800 m at Byrd Station in 1967–68 have been found to have recrystallized while in storage in the United States. Such recrystallization, inferred to have occurred when temperatures in the storage facility rose above about – 14°C, would not have been discovered if thin sections of the cores had not been prepared and photographed at the drill site within hours of pulling the cores to the surface. It was only after new sections of the long stored cores were compared with the original sections that the full extent of recrystallization was revealed. The recrystallized structure emulates in both texture and fabric those observed in naturally annealed ice in the bottom 350 m at Byrd Station. It is concluded that polar ice cores should be stored at temperatures of –20°C or colder in order to inhibit or minimize post-drilling recrystallization.

scholarly journals Acidity of Polar Ice Cores in Relation to Absolute Dating, Past Volcanism, and Radio–Echoes

1980 ◽  
Vol 25 (93) ◽  
pp. 359-372 ◽  
Author(s):  
C. U. Hammer
Keyword(s):  
Ice Core ◽  
Ice Cores ◽  
Volcanic Eruptions ◽  
Electrical Current ◽  
Polar Ice ◽  
Initial Current ◽  
Simple Method ◽  
High Acidity ◽  
Polar Ice Sheets ◽  
Absolute Dating

Abstract A simple method is described for detecting annual stratification of ice cores, and layers of high acidity due to violent volcanic eruptions in the past. The method is based on a relationship between the H3O+ concentration (pH) of melted samples and the electrical current between two brass electrodes moved along the cleaned ice-core surface. The “conductivity” is explained in terms of the initial current in the build-up of space charges. Acidity and current profiles are shown through layers deposited soon after historically well-known volcanic eruptions, such as Katmai, a.d. 1912, Tambora, a.d. 1815, Laki, a.d. 1783, Hekla, a.d. 1104, and Thera (Santorin) c. 1400 b.c. High-acidity layers seem to be the cause for the internal radio-echo layers in polar ice sheets.

Coupled artefact production of methane, ethane, and propane in polar ice cores

2020 ◽  
Author(s):  
Jochen Schmitt ◽  
James Lee ◽  
Jon Edwards ◽  
Edward Brook ◽  
Thomas Blunier ◽  
...  
Keyword(s):  
Ice Core ◽  
Empirical Relation ◽  
Ice Cores ◽  
Underlying Mechanism ◽  
Extraction Methods ◽  
Isotopic Signature ◽  
Atmospheric Composition ◽  
Last Interglacial ◽  
Polar Ice ◽  
The Past

<p>Air inclusions trapped in polar ice provide unique records of the past atmospheric composition ranging from key greenhouse gases to short-lived trace gases like ethane and propane. Provided the analyzed species concentrations and their isotopic fingerprints accurately reflect past atmospheric composition, valuable constraints can be put onto biogeochemical cycles. However, it is already known that not all drill sites or specific time intervals are equally suitable to derive artefact-free gas records; e.g., CO<sub>2</sub> data from Greenland ice is overprinted by CO<sub>2</sub> ‘in situ’ production due to impurities in the ice, and only the cleaner Antarctic ice allows to reconstruct past atmospheric CO<sub>2</sub>.</p><p>Until recently, CH<sub>4</sub> artefacts in polar ice were only detected on melt affected samples or for short spikes related to exceptional impurity deposition events (Rhodes et al 2013). However, careful comparison of CH<sub>4</sub> records obtained using different extraction methods revealed disagreements among Greenland CH<sub>4</sub> records and initiated targeted experiments.</p><p>Here, we report experimental findings of CH<sub>4</sub> artefacts occurring in dust-rich sections of Greenland ice cores. The artefact production happens during the melt extraction step (‘in extractu’) of the classic wet extraction technique and typically reaches 20 ppb in dusty stadial ice which causes erroneous reconstructions of the interhemispheric CH<sub>4</sub> difference and strongly affects the hydrogen isotopic signature of CH<sub>4</sub> (Lee et al. 2020). The measured CH4 excess is proportional to the amount of mineral dust in the ice. Knowing the empirical relation between produced CH4 and the dust concentration of a sample allows a first-order correction of existing CH4 data sets and to revise previous interpretations.</p><p>To shed light on the underlying mechanism, we analyzed samples for other short-chain alkanes ethane (C<sub>2</sub>H<sub>6</sub>) and propane (C<sub>3</sub>H<sub>8</sub>). The production of CH<sub>4</sub> was always tightly accompanied with C<sub>2</sub>H<sub>6</sub> and C<sub>3</sub>H<sub>8</sub> production at amounts exceeding the past atmospheric background levels derived from low-dust samples. Independent of the produced amounts, CH<sub>4</sub>, C<sub>2</sub>H<sub>6</sub>, and C<sub>3</sub>H<sub>8</sub> were produced in molar ratios of roughly 16:2:1, respectively. The simultaneous production at these ratios does not point to an anaerobic methanogenic origin which typically exhibits methane-to-ethane ratios of >>100. Such alkane patterns are indicative of abiotic degradation of organic matter as found in sediments.</p><p>We found this specific alkane pattern not only for dust-rich samples but also for samples that were affected by surface melting from the last interglacial (NEEM ice core) with low dust concentrations. This implies that the necessary precursor is an impurity also present in low-dust ice and the step leading to the production of the alkanes could then be activated when a sufficient boundary condition is met for the production, e.g. by melt/refreeze of surface snow.</p>

scholarly journals How well can we parameterize past accumulation rates in polar ice sheets?

1997 ◽  
Vol 25 ◽  
pp. 418-422 ◽  
Author(s):  
Eric J. Steig
Keyword(s):  
Accumulation Rate ◽  
Order Approximation ◽  
Ice Core ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Ice Cores ◽  
Accumulation Rates ◽  
Polar Ice ◽  
Polar Ice Sheets ◽  
First Order Approximation

An important component of models of the cryosphere is the calculation of accumulation rates over polar ice sheets. As a first-order approximation, many models rely on the assumption that temperature is the main controlling factor for precipitation. However, compilation of available ice-core data, including a new core from Taylor Dome, East Antarctica, suggests that precipitation is significantly decoupled from temperature for a large proportion of both the Greenland and Antarctic ice sheets. While the estimated glacial-to-interglacial change in temperature does not differ greatly among ice cores from each ice sheet, the estimated change in accumulation rate varies by more than a factor of 2. A simple vapor-pressure parameterization gives reasonable estimates of accumulation in the ice-sheet interior, but this is not necessarily the case close to the ice-sheet margin, where synoptic weather systems are important.

scholarly journals How well can we parameterize past accumulation rates in polar ice sheets?

1997 ◽  
Vol 25 ◽  
pp. 418-422 ◽  
Author(s):  
Eric J. Steig
Keyword(s):  
Accumulation Rate ◽  
Order Approximation ◽  
Ice Core ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Ice Cores ◽  
Accumulation Rates ◽  
Polar Ice ◽  
Polar Ice Sheets ◽  
First Order Approximation

An important component of models of the cryosphere is the calculation of accumulation rates over polar ice sheets. As a first-order approximation, many models rely on the assumption that temperature is the main controlling factor for precipitation. However, compilation of available ice-core data, including a new core from Taylor Dome, East Antarctica, suggests that precipitation is significantly decoupled from temperature for a large proportion of both the Greenland and Antarctic ice sheets. While the estimated glacial-to-interglacial change in temperature does not differ greatly among ice cores from each ice sheet, the estimated change in accumulation rate varies by more than a factor of 2. A simple vapor-pressure parameterization gives reasonable estimates of accumulation in the ice-sheet interior, but this is not necessarily the case close to the ice-sheet margin, where synoptic weather systems are important.

scholarly journals Acidity of Polar Ice Cores in Relation to Absolute Dating, Past Volcanism, and Radio–Echoes

1980 ◽  
Vol 25 (93) ◽  
pp. 359-372 ◽  
Author(s):  
C. U. Hammer
Keyword(s):  
Ice Core ◽  
Ice Cores ◽  
Volcanic Eruptions ◽  
Electrical Current ◽  
Polar Ice ◽  
Initial Current ◽  
Simple Method ◽  
High Acidity ◽  
Polar Ice Sheets ◽  
Absolute Dating

AbstractA simple method is described for detecting annual stratification of ice cores, and layers of high acidity due to violent volcanic eruptions in the past. The method is based on a relationship between the H3O+concentration (pH) of melted samples and the electrical current between two brass electrodes moved along the cleaned ice-core surface. The “conductivity” is explained in terms of the initial current in the build-up of space charges. Acidity and current profiles are shown through layers deposited soon after historically well-known volcanic eruptions, such as Katmai, a.d. 1912, Tambora, a.d. 1815, Laki, a.d. 1783, Hekla, a.d. 1104, and Thera (Santorin)c. 1400 b.c. High-acidity layers seem to be the cause for the internal radio-echo layers in polar ice sheets.

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