Deep ice as a geochemical reactor: insights from iron speciation and mineralogy of dust in the Talos Dome ice core (East Antarctica)

Abstract. Thanks to its insolubility, mineral dust is considered a stable proxy in polar ice cores. With this study we show that below an ice-depth of 1000 m, the Talos Dome ice core (Ross Sea sector of East Antarctica) presents evident and progressive signs of post-depositional processes affecting the mineral dust records. We applied a suite of established and cutting edge techniques to investigate the properties of dust present in the Talos Dome ice core, ranging from concentration and grain-size to elemental-composition and Fe-mineralogy. Results show that through acidic/oxidative weathering, the conditions of deep ice at Talos Dome promote the dissolution of specific minerals and the englacial formation of others, deeply affecting dust primitive features. The expulsion of acidic atmospheric species from ice-grains and their concentration in localized environments is likely the main process responsible for englacial reactions and is related with ice re-crystallization. Deep ice can be seen as a "geochemical reactor" capable of fostering complex reactions which involve both soluble and insoluble impurities. Fe-bearing minerals can efficiently be used to explore such transformations.

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Deep ice as a geochemical reactor: insights from iron speciation and mineralogy of dust in the Talos Dome ice core (East Antarctica)

The Cryosphere ◽

10.5194/tc-15-4807-2021 ◽

2021 ◽

Vol 15 (10) ◽

pp. 4807-4822

Author(s):

Giovanni Baccolo ◽

Barbara Delmonte ◽

Elena Di Stefano ◽

Giannantonio Cibin ◽

Ilaria Crotti ◽

...

Keyword(s):

Ross Sea ◽

Mineral Dust ◽

Ice Core ◽

Ice Cores ◽

East Antarctica ◽

Main Process ◽

Polar Ice ◽

Atmospheric Species ◽

Depositional Processes ◽

Fe Mineralogy

Abstract. Thanks to its insolubility, mineral dust is considered a stable proxy in polar ice cores. With this study we show that the Talos Dome ice core (TALDICE, Ross Sea sector of East Antarctica) displays evident and progressive signs of post-depositional processes affecting the mineral dust record below 1000 m deep. We apply a suite of established and cutting-edge techniques to investigate the properties of dust in TALDICE, ranging from concentration and grain size to elemental composition and Fe mineralogy. Results show that through acidic/oxidative weathering, the conditions of deep ice at Talos Dome promote the dissolution of specific minerals and the englacial formation of others, affecting primitive dust features. The expulsion of acidic atmospheric species from ice grains and their concentration in localized environments is likely the main process responsible for englacial reactions. Deep ice can be seen as a “geochemical reactor” capable of fostering complex reactions which involve both soluble and insoluble impurities. Fe-bearing minerals can efficiently help in exploring such transformations.

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High-resolution mineral dust and sea ice proxy records from the Talos Dome ice core

Climate of the Past ◽

10.5194/cp-9-2789-2013 ◽

2013 ◽

Vol 9 (6) ◽

pp. 2789-2807 ◽

Cited By ~ 18

Author(s):

S. Schüpbach ◽

U. Federer ◽

P. R. Kaufmann ◽

S. Albani ◽

C. Barbante ◽

...

Keyword(s):

Southern Ocean ◽

Sea Ice ◽

Ross Sea ◽

Transport Model ◽

Mineral Dust ◽

Ice Core ◽

Ice Cores ◽

Last Interglacial ◽

The Holocene ◽

Proxy Records

Abstract. In this study we report on new non-sea salt calcium (nssCa2+, mineral dust proxy) and sea salt sodium (ssNa+, sea ice proxy) records along the East Antarctic Talos Dome deep ice core in centennial resolution reaching back 150 thousand years (ka) before present. During glacial conditions nssCa2+ fluxes in Talos Dome are strongly related to temperature as has been observed before in other deep Antarctic ice core records, and has been associated with synchronous changes in the main source region (southern South America) during climate variations in the last glacial. However, during warmer climate conditions Talos Dome mineral dust input is clearly elevated compared to other records mainly due to the contribution of additional local dust sources in the Ross Sea area. Based on a simple transport model, we compare nssCa2+ fluxes of different East Antarctic ice cores. From this multi-site comparison we conclude that changes in transport efficiency or atmospheric lifetime of dust particles do have a minor effect compared to source strength changes on the large-scale concentration changes observed in Antarctic ice cores during climate variations of the past 150 ka. Our transport model applied on ice core data is further validated by climate model data. The availability of multiple East Antarctic nssCa2+ records also allows for a revision of a former estimate on the atmospheric CO2 sensitivity to reduced dust induced iron fertilisation in the Southern Ocean during the transition from the Last Glacial Maximum to the Holocene (T1). While a former estimate based on the EPICA Dome C (EDC) record only suggested 20 ppm, we find that reduced dust induced iron fertilisation in the Southern Ocean may be responsible for up to 40 ppm of the total atmospheric CO2 increase during T1. During the last interglacial, ssNa+ levels of EDC and EPICA Dronning Maud Land (EDML) are only half of the Holocene levels, in line with higher temperatures during that period, indicating much reduced sea ice extent in the Atlantic as well as the Indian Ocean sector of the Southern Ocean. In contrast, Holocene ssNa+ flux in Talos Dome is about the same as during the last interglacial, indicating that there was similar ice cover present in the Ross Sea area during MIS 5.5 as during the Holocene.

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Snow Stratigraphic Studies At Dome C, East Antarctica: An Investigation Of Depositional and Diagenetic Processes

Annals of Glaciology ◽

10.3189/s0260305500002846 ◽

1982 ◽

Vol 3 ◽

pp. 239-242 ◽

Cited By ~ 6

Author(s):

J. M. Palais ◽

I. M. Whillans ◽

C. Bull

Keyword(s):

Ice Sheets ◽

Ice Cores ◽

Snow Accumulation ◽

East Antarctica ◽

Polar Ice ◽

Depositional Processes ◽

Diagenetic Processes ◽

Snow Stratigraphy ◽

Stratigraphic Record ◽

Polar Ice Sheets

The increased interest in past climatic changes, as revealed by studies of long ice cores from polar ice sheets, has stressed the need for a better understanding of the development of the stratigraphic record preserved in these cores. This paper presents some results of surface investigations at Dome C (74°30'S, 123°10'E), East Antarctica, carried out in austral summers 1978-79 and 1979-80. An explanation is presented of the snow stratigraphy, in terms of depositional and post-depositional processes, that is supported by detailed accumulation measurements at stakes and by snow-pit studies. Temporal and areal variability of snow accumulation are investigated to determine how representative the results interpreted from a single core might be for the Dome C region. Finally, the reliability of several stratigraphic methods for defining annual layers is assessed.Snow-pit studies show that major depositional features are preserved with depth. Visible annual strata at Dome C are composed of thin, hard crusts overlying thicker layers of soft to medium-hard snow. Low density depth-hoar layers, when they occur, are usually found below the thin, hard crusts. Depth profiles of gross 8-radioactivity and of microparticles concentration exhibit annual cyclicity which, together with the detailed visible stratigraphy, can be used to assign dates to the layers.

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Snow Stratigraphic Studies At Dome C, East Antarctica: An Investigation Of Depositional and Diagenetic Processes

Annals of Glaciology ◽

10.1017/s0260305500002846 ◽

1982 ◽

Vol 3 ◽

pp. 239-242 ◽

Cited By ~ 28

Author(s):

J. M. Palais ◽

I. M. Whillans ◽

C. Bull

Keyword(s):

Ice Sheets ◽

Ice Cores ◽

Snow Accumulation ◽

East Antarctica ◽

Polar Ice ◽

Depositional Processes ◽

Diagenetic Processes ◽

Snow Stratigraphy ◽

Stratigraphic Record ◽

Polar Ice Sheets

The increased interest in past climatic changes, as revealed by studies of long ice cores from polar ice sheets, has stressed the need for a better understanding of the development of the stratigraphic record preserved in these cores. This paper presents some results of surface investigations at Dome C (74°30'S, 123°10'E), East Antarctica, carried out in austral summers 1978-79 and 1979-80. An explanation is presented of the snow stratigraphy, in terms of depositional and post-depositional processes, that is supported by detailed accumulation measurements at stakes and by snow-pit studies. Temporal and areal variability of snow accumulation are investigated to determine how representative the results interpreted from a single core might be for the Dome C region. Finally, the reliability of several stratigraphic methods for defining annual layers is assessed. Snow-pit studies show that major depositional features are preserved with depth. Visible annual strata at Dome C are composed of thin, hard crusts overlying thicker layers of soft to medium-hard snow. Low density depth-hoar layers, when they occur, are usually found below the thin, hard crusts. Depth profiles of gross 8-radioactivity and of microparticles concentration exhibit annual cyclicity which, together with the detailed visible stratigraphy, can be used to assign dates to the layers.

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The impact of glacier retreat from the Ross Sea on local climate: Characterization of mineral dust in the Taylor Dome ice core, East Antarctica

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2016.03.035 ◽

2016 ◽

Vol 444 ◽

pp. 34-44 ◽

Cited By ~ 13

Author(s):

S.M. Aarons ◽

S.M. Aciego ◽

P. Gabrielli ◽

B. Delmonte ◽

J.M. Koornneef ◽

...

Keyword(s):

Ross Sea ◽

Mineral Dust ◽

Ice Core ◽

East Antarctica ◽

Glacier Retreat ◽

Local Climate ◽

The Impact

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Interpreting last glacial to Holocene dust changes at Talos Dome (East Antarctica): implications for atmospheric variations from regional to hemispheric scales

Climate of the Past Discussions ◽

10.5194/cpd-8-145-2012 ◽

2012 ◽

Vol 8 (1) ◽

pp. 145-168 ◽

Cited By ~ 2

Author(s):

S. Albani ◽

B. Delmonte ◽

V. Maggi ◽

C. Baroni ◽

J.-R. Petit ◽

...

Keyword(s):

Ross Sea ◽

Atmospheric Transport ◽

Spatial Scales ◽

Ice Core ◽

Ice Cores ◽

East Antarctica ◽

Deposition Flux ◽

Stable Water Isotopes ◽

Dust Deposition ◽

Last Glacial

Abstract. Central East Antarctica ice cores preserve stratigraphic records of mineral dust originating from remote sources in the Southern Hemisphere, and represent useful indicators of climatic variations on glacial-interglacial time scales. The peripheries of the East Antarctic Ice Sheet, where ice-free areas with the potential to emit dust exist, have been less explored from this point of view. Here we present a new profile of dust deposition flux and grain size distributions from an ice core drilled at Talos Dome (Northern Victoria Land, East Antarctica), where there is a significant input of dust from proximal Antarctic ice-free areas. We analyze dust and stable water isotopes variations from the Last Glacial Maximum to the Late Holocene, and compare them to the EPICA Dome C profiles from Central East Antarctica. The smaller glacial-interglacial variations at Talos Dome compared to Dome C, and a distinctive decreasing trend during the Holocene, characterize the TALDICE dust profile. By deciphering the composite dust signal from both remote and local sources, we show the potential of this combined proxy of source activity and atmospheric transport to give information on both regional and larger spatial scales. In particular, we show how a regional signal, which we related to the deglaciation history of the Ross Sea embayment, can be superimposed to the broader scale glacial-interglacial variability that characterizes other Antarctic sites.

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Interpreting last glacial to Holocene dust changes at Talos Dome (East Antarctica): implications for atmospheric variations from regional to hemispheric scales

Climate of the Past ◽

10.5194/cp-8-741-2012 ◽

2012 ◽

Vol 8 (2) ◽

pp. 741-750 ◽

Cited By ~ 41

Author(s):

S. Albani ◽

B. Delmonte ◽

V. Maggi ◽

C. Baroni ◽

J.-R. Petit ◽

...

Keyword(s):

Ross Sea ◽

Atmospheric Transport ◽

Spatial Scales ◽

Ice Core ◽

Ice Cores ◽

East Antarctica ◽

Deposition Flux ◽

Stable Water Isotopes ◽

Dust Deposition ◽

Last Glacial

Abstract. Central East Antarctic ice cores preserve stratigraphic records of mineral dust originating from remote sources in the Southern Hemisphere, and represent useful indicators of climatic variations on glacial-interglacial time scales. The peripheries of the East Antarctic Ice Sheet, where ice-free areas with the potential to emit dust exist, have been less explored from this point of view. Here, we present a new profile of dust deposition flux and grain size distributions from an ice core drilled at Talos Dome (TALDICE, Northern Victoria Land, East Antarctica), where there is a significant input of dust from proximal Antarctic ice-free areas. We analyze dust and stable water isotopes variations from the Last Glacial Maximum to the Late Holocene, and compare them to the EPICA Dome C profiles from central East Antarctica. The smaller glacial-interglacial variations at Talos Dome compared to Dome C and a distinctive decreasing trend during the Holocene characterize the TALDICE dust profile. By deciphering the composite dust signal from both remote and local sources, we show the potential of this combined proxy of source activity and atmospheric transport to give information on both regional and larger spatial scales. In particular, we show how a regional signal, which we relate to the deglaciation history of the Ross Sea embayment, can be superimposed to the broader scale glacial-interglacial variability that characterizes other Antarctic sites.

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Methanesulphonic acid movement in solid ice cores

Annals of Glaciology ◽

10.3189/172756404781814645 ◽

2004 ◽

Vol 39 ◽

pp. 540-544 ◽

Cited By ~ 13

Author(s):

Barbara T. Smith ◽

Tas D. Van Ommen ◽

Mark A. J. Curran

Keyword(s):

Diffusion Coefficient ◽

Biological Activity ◽

Sea Ice ◽

Diffusion Mechanism ◽

Ice Core ◽

Ice Cores ◽

East Antarctica ◽

The Core ◽

Central Value

AbstractMethanesulphonic acid (MSA) is an important trace-ion constituent in ice cores, with connections to biological activity and sea-ice distribution. Post-depositional movement of MSA has been documented in firn, and this study investigates movement in solid ice by measuring variations in MSA distribution across several horizontal sections from an ice core after 14.5 years storage. The core used is from below the bubble close-off depth at Dome Summit South, Law Dome, East Antarctica. MSA concentration was studied at 3 and 0.5 cm resolution across the core widths. Its distribution was uniform through the core centres, but the outer 3 cm showed gradients in concentrations down to less than half of the central value at the core edge. This effect is consistent with diffusion to the surrounding air during its 14.5 year storage. The diffusion coefficient is calculated to be 2 ×10–13 m2 s–1, and the implications for the diffusion mechanism are discussed.

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Reconstructing Antarctic snow accumulation using nitrogen isotopes of nitrate

10.5194/egusphere-egu21-672 ◽

2021 ◽

Author(s):

Pete D. Akers ◽

Joël Savarino ◽

Nicolas Caillon ◽

Mark Curran ◽

Tas Van Ommen

Keyword(s):

Nitrogen Isotopes ◽

Full Range ◽

Ice Core ◽

Ice Cores ◽

Snow Accumulation ◽

East Antarctica ◽

Accumulation Rates ◽

Sea Levels ◽

Antarctic Snow ◽

Parallel Reconstruction

Precise Antarctic snow accumulation estimates are needed to understand past and future changes in global sea levels, but standard reconstructions using water isotopes suffer from competing isotopic effects external to accumulation. We present here an alternative accumulation proxy based on the post-depositional photolytic fractionation of nitrogen isotopes (d15N) in nitrate. On the high plateau of East Antarctica, sunlight penetrating the uppermost snow layers converts snow-borne nitrate into nitrogen oxide gas that can be lost to the atmosphere. This nitrate loss favors 14NO3- over 15NO3-, and thus the d15N of nitrate remaining in the snow will steadily increase until the nitrate is eventually buried beneath the reach of light. Because the duration of time until burial is dependent upon the rate of net snow accumulation, sites with lower accumulation rates have a longer burial wait and thus higher d15N values. A linear relationship (r2 = 0.86) between d15N and net accumulation-1 is calculated from over 120 samples representing 105 sites spanning East Antarctica. These sites largely encompass the full range of snow accumulation rates observed in East Antarctica, from 25 kg m-2 yr-1 at deep interior sites to >400 kg m-2 yr-1 at near coastal sites. We apply this relationship as a transfer function to an Aurora Basin ice core to produce a 700-year record of accumulation changes. Our nitrate-based estimate compares very well with a parallel reconstruction for Aurora Basin that uses volcanic horizons and ice-penetrating radar. Continued improvements to our database may enable precise independent estimates of millennial-scale accumulation changes using deep ice cores such as EPICA Dome C and Beyond EPICA-Oldest Ice.

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Climate dependent contrast in surface mass balance in East Antarctica over the past 216 ka

Journal of Glaciology ◽

10.1017/jog.2016.85 ◽

2016 ◽

Vol 62 (236) ◽

pp. 1037-1048 ◽

Cited By ~ 4

Author(s):

F. PARRENIN ◽

S. FUJITA ◽

A. ABE-OUCHI ◽

K. KAWAMURA ◽

V. MASSON-DELMOTTE ◽

...

Keyword(s):

Mass Balance ◽

Ice Core ◽

Ice Cores ◽

East Antarctica ◽

Surface Mass Balance ◽

Last Interglacial ◽

Surface Mass ◽

The Past ◽

Water Stable Isotope ◽

Global Mean Sea Level

ABSTRACTDocumenting past changes in the East Antarctic surface mass balance is important to improve ice core chronologies and to constrain the ice-sheet contribution to global mean sea-level change. Here we reconstruct past changes in the ratio of surface mass balance (SMB ratio) between the EPICA Dome C (EDC) and Dome Fuji (DF) East Antarctica ice core sites, based on a precise volcanic synchronization of the two ice cores and on corrections for the vertical thinning of layers. During the past 216 000 a, this SMB ratio, denoted SMBEDC/SMBDF, varied between 0.7 and 1.1, being small during cold periods and large during warm periods. Our results therefore reveal larger amplitudes of changes in SMB at EDC compared with DF, consistent with previous results showing larger amplitudes of changes in water stable isotopes and estimated surface temperature at EDC compared with DF. Within the last glacial inception (Marine Isotope Stages, MIS-5c and MIS-5d), the SMB ratio deviates by up to 0.2 from what is expected based on differences in water stable isotope records. Moreover, the SMB ratio is constant throughout the late parts of the current and last interglacial periods, despite contrasting isotopic trends.

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