scholarly journals Dating of an East Antarctic ice core (GV7) by high resolution chemical stratigraphies

2021 ◽  
Author(s):  
Raffaello Nardin ◽  
Mirko Severi ◽  
Alessandra Amore ◽  
Silvia Becagli ◽  
Francois Burgay ◽  
...  
Keyword(s):  
Environmental Changes ◽  
18Th Century ◽  
Accumulation Rate ◽  
Ice Core ◽  
Methanesulfonic Acid ◽  
Oxygen Isotopic Composition ◽  
Snow Accumulation ◽  
Sea Salt ◽  
The Core ◽  
History Of

Abstract. Ice core dating is the first step for a correct interpretation of climatic and environmental changes. In this work, we release a stratigraphic dating of the uppermost 197 m of the 250 m deep GV7(B) ice core (drilling site, 70°41’S, 158°52’E, 1950 m a.s.l.) with a sub-annual resolution. Chemical stratigraphies of NO3−, MSA (methanesulfonic acid), non-sea salt SO42−, sea-salt ions and the oxygen isotopic composition (δ18O) were used in the annual layer counting upon the identification of a seasonal profile in their records. Different procedures were tested and thanks to the volcanic history of the core, obtained in previous works, an accurate age-depth correlation was obtained for the period 1179–2009 CE. Once the dating of the core was finalized, the annual mean accumulation rate was evaluated throughout the analyzed 197 m of the core, obtaining an annually resolved history of the snow accumulation on site in the last millennium. A small, yet consistent, rise in accumulation rate was found for the last 830 years since the middle of the 18th century.

scholarly journals Dating of the GV7 East Antarctic ice core by high-resolution chemical records and focus on the accumulation rate variability in the last millennium

2021 ◽  
Vol 17 (5) ◽  
pp. 2073-2089
Author(s):  
Raffaello Nardin ◽  
Mirko Severi ◽  
Alessandra Amore ◽  
Silvia Becagli ◽  
Francois Burgay ◽  
...  
Keyword(s):  
Environmental Changes ◽  
18Th Century ◽  
Accumulation Rate ◽  
Seasonal Pattern ◽  
Ice Core ◽  
Methanesulfonic Acid ◽  
Snow Accumulation ◽  
Sea Salt ◽  
Last Millennium ◽  
Annual Layer

Abstract. Ice core dating is the first step for a correct interpretation of climatic and environmental changes. In this work, we release the dating of the uppermost 197 m of the 250 m deep GV7(B) ice core (drill site, 70∘41′ S, 158∘52′ E; 1950 m a.s.l. in Oates Land, East Antarctica) with a sub-annual resolution. Chemical records of NO3-, MSA (methanesulfonic acid), non-sea-salt SO42- (nssSO42-), sea-salt ions and water stable isotopes (δ18O) were studied as candidates for dating due to their seasonal pattern. Different procedures were tested but the nssSO42- record proved to be the most reliable on the short- and long-term scales, so it was chosen for annual layer counting along the whole ice core. The dating was constrained by using volcanic signatures from historically known events as tie points, thus providing an accurate age–depth relationship for the period 1179–2009 CE. The achievement of the complete age scale allowed us to calculate the annual mean accumulation rate throughout the analyzed 197 m of the core, yielding an annually resolved history of the snow accumulation on site in the last millennium. A small yet consistent rise in accumulation rate (Tr = 1.6, p<0.001) was found for the last 830 years starting around mid-18th century.

scholarly journals Investigation of the 18O Content of a 100 m Ice Core From the Ronne Ice Shelf, Antarctica

1988 ◽  
Vol 10 ◽  
pp. 43-47 ◽  
Author(s):  
W. Graf ◽  
O. Reinwarth ◽  
H. Moser ◽  
W. Stichler
Keyword(s):  
Flow Model ◽  
Accumulation Rate ◽  
Ice Core ◽  
Snow Accumulation ◽  
Two Dimensional ◽  
Ice Shelf ◽  
Short Term ◽  
The Core ◽  
Two Dimensional Flow ◽  
Field Season

A 100 m ice core from the Ronne Ice Shelf, drilled during the 1983-84 field season, was dated by isotopic stratigraphy, using the well-known seasonal variation in the 18O content in firn and ice; the layers at a depth of 89 m are probably 400 years old. Layer thicknesses deduced from the 18O profile indicate short-term variations of the snow-accumulation rate over the last 400 years. The area of deposition of the material recovered with the core is estimated by a two-dimensional flow model and by the 18O content of the core, which decreases from –27.5‰ in the upper part of the core to –32.0‰ at 89 m depth.

scholarly journals A 2700-year annual timescale and accumulation history for an ice core from Roosevelt Island, West Antarctica

2019 ◽  
Vol 15 (2) ◽  
pp. 751-779 ◽  
Author(s):  
Mai Winstrup ◽  
Paul Vallelonga ◽  
Helle A. Kjær ◽  
Tyler J. Fudge ◽  
James E. Lee ◽  
...  
Keyword(s):  
Sea Ice ◽  
Accumulation Rate ◽  
Ice Core ◽  
Snow Accumulation ◽  
Accumulation Rates ◽  
West Antarctica ◽  
Sea Ice Extent ◽  
Amundsen Sea ◽  
The Core ◽  
Accumulation History

Abstract. We present a 2700-year annually resolved chronology and snow accumulation history for the Roosevelt Island Climate Evolution (RICE) ice core, Ross Ice Shelf, West Antarctica. The core adds information on past accumulation changes in an otherwise poorly constrained sector of Antarctica. The timescale was constructed by identifying annual cycles in high-resolution impurity records, and it constitutes the top part of the Roosevelt Island Ice Core Chronology 2017 (RICE17). Validation by volcanic and methane matching to the WD2014 chronology from the WAIS Divide ice core shows that the two timescales are in excellent agreement. In a companion paper, gas matching to WAIS Divide is used to extend the timescale for the deeper part of the core in which annual layers cannot be identified. Based on the annually resolved timescale, we produced a record of past snow accumulation at Roosevelt Island. The accumulation history shows that Roosevelt Island experienced slightly increasing accumulation rates between 700 BCE and 1300 CE, with an average accumulation of 0.25±0.02 m water equivalent (w.e.) per year. Since 1300 CE, trends in the accumulation rate have been consistently negative, with an acceleration in the rate of decline after the mid-17th century. The current accumulation rate at Roosevelt Island is 0.210±0.002 m w.e. yr−1 (average since 1965 CE, ±2σ), and it is rapidly declining with a trend corresponding to 0.8 mm yr−2. The decline observed since the mid-1960s is 8 times faster than the long-term decreasing trend taking place over the previous centuries, with decadal mean accumulation rates consistently being below average. Previous research has shown a strong link between Roosevelt Island accumulation rates and the location and intensity of the Amundsen Sea Low, which has a significant impact on regional sea-ice extent. The decrease in accumulation rates at Roosevelt Island may therefore be explained in terms of a recent strengthening of the ASL and the expansion of sea ice in the eastern Ross Sea. The start of the rapid decrease in RICE accumulation rates observed in 1965 CE may thus mark the onset of significant increases in regional sea-ice extent.

scholarly journals Sensitivity of chemical species to climatic changes in the last 45 kyr as revealed by high-resolution Dome C (East Antarctica) ice-core analysis

2004 ◽  
Vol 39 ◽  
pp. 457-466 ◽  
Author(s):  
Roberto Udisti ◽  
Silvia Becagli ◽  
Silvia Benassai ◽  
Martine De Angelis ◽  
Margareta E. Hansson ◽  
...  
Keyword(s):  
High Resolution ◽  
Environmental Changes ◽  
Accumulation Rate ◽  
Ice Core ◽  
Chemical Species ◽  
Climatic Changes ◽  
Snow Accumulation ◽  
Last Deglaciation ◽  
Temperature Trends ◽  
Chemical Profiles

AbstractTo assess the cause/effect relationship between climatic and environmental changes, we report high-resolution chemical profiles of the Dome C ice core (788m, 45 kyr), drilled in the framework of the European Project for Ice Coring in Antarctica (EPICA). Snow-concentration and depositional-flux changes during the last deglaciation were compared with climatic changes, derived by δD profile. Concentration and temperature profiles showed an anticorrelation, driven by changes in source intensity and transport efficiency of the atmospheric aerosol and by snow accumulation-rate variations. The flux calculation allowed correction for accumulation rate. While sulphate and ammonium fluxes are quite constant, Na+, Mg2+ and Ca2+ underwent the greatest changes, showing fluxes respectively about two, three and six times lower in the Holocene than in the Last Glacial Maximum. Chloride, nitrate and methanesulphonic acid (MSA) also exhibited large changes, but their persistence depends on depositional and post-depositional effects. The comparison between concentrations and δD profiles revealed leads and lags between chemical and temperature trends: Ca2+ and nitrate preceded by about 300 years the δD increase at the deglaciation onset, while MSA showed a 400 year delay. Generally, all components reached low Holocene values in the first deglaciation step (18.0–14.0 kyr BP), but Na+, Mg2+ and nitrate show changes during the Antarctic Cold Reversal (14.0– 12.5 kyr BP).

scholarly journals 200 years of isotope and chemical records in a firn core from Hercules Névé, northern Victoria Land, Antarctica

1999 ◽  
Vol 29 ◽  
pp. 106-112 ◽  
Author(s):  
B. Stenni ◽  
R. Caprioli ◽  
L. Cimino ◽  
C. Cremisini ◽  
O. Flora ◽  
...  
Keyword(s):  
Accumulation Rate ◽  
Ice Core ◽  
Volcanic Eruptions ◽  
Snow Accumulation ◽  
The Core ◽  
Victoria Land ◽  
Chemical Profiles ◽  
The 19Th Century ◽  
Calculated Average ◽  
Firn Core

AbstractA 42.2 m firn core was collected at the Hercules Névé plateau (100 km inland and 2960 m a.s.L), northern Victoria Land, during the 1994-95 Italian Antarctic Expedition. Chemical (Cl–, NO3–, SO42–’; δ18O δ18O δ18O; m-2a-1) and isotope (5180) analyses were performed to evaluate the snow-accumulation rate at this site. Tritium measurements were performed in the upper part of the core to narrow down the dating of the core.High nssSO42- concentrations seem to be related to some explosive volcanic eruptions, such as Tambora (AD 1815) and the preceding event called "Unknown" (AD 1809), Coseguina (AD 1835), Makjan (AD 1861), Krakatoa (AD 1883) and Tarawera (AD 1886).A comparison between the seasonal variations observed in the isotope and chemical profiles was carried out in order to reduce the dating uncertainty, using the tritium and the volcanic markers as time constraints. A deposition period of 222 years was determined.The 3 year smoothed «5180 profile shows more negative values from the bottom of the core (dated AD 1770) throughout the 19th century, suggesting "cooler" conditions, in agreement with other East Antarctic ice-core records! Subsequently, a general increase in δ180-values is observed.The calculated average snow-accumulation rates between the above-mentioned time markers are 111-129 kg m-2a-1.

scholarly journals A 485 year record of atmospheric chloride, nitrate and sulfate: results of chemical analysis of ice cores from Dyer Plateau, Antarctic Peninsula

1995 ◽  
Vol 21 ◽  
pp. 182-188 ◽  
Author(s):  
Jihong Cole Dai ◽  
Lonnie G. Thompson ◽  
Ellen Mosley-Thompson
Keyword(s):  
Sea Water ◽  
Accumulation Rate ◽  
Linear Regression Analysis ◽  
Ice Core ◽  
Ice Cores ◽  
Snow Accumulation ◽  
Sea Salt ◽  
Volcanic Emissions ◽  
Data Set ◽  
Snow Chemistry

Detailed ionic analyses of Dyer Plateau snow show that major soluble impurities in snow consist of sodium (Na+), chloride (Cl−), nitrate (NO3−), sulfate (SO42−), and acidity (H+). The ratios of Na+ to Cl− concentrations are close to that of sea water, indicating little or no fractionation of sea-salt aerosols. The analyses of core sections from three sites along a 10 km transect show that local spatial variation of snow chemistry in this area is minimal and that temporal (decadal, inter-annual and sub-annual) variations in snow chemistry are very well preserved.Anion analyses of the upper 181 m section of two 235 m ice cores yield a data set of 485 years (1505-1989) of annual snow accumulation and fluxes of Cl−, NO3−, and non-sea-salt (nss) SO42−. No significant long-term trends are observed in any of the anion fluxes. This is consistent with other Antarctic ice-core records showing no significant anthropogenic atmospheric pollution in the high southern latitudes. Linear regression analysis shows that Cl− flux is independent of snow-accumulation rate. Significant positive correlations are found between accumulation rate and both NO3− flux and background nss-SO42− flux. These results suggest that dry deposition is primarily responsible for air-to-ground Cl− flux while wet deposition dominates the NO3− and nss-SO42− flux (≥90% and ≥75%, respectively). The nss-S042− fluxes provide a chronology of explosive volcanic emissions reaching the Antarctic region for the past 485 years.

scholarly journals Chronological characteristics for snow accumulation on Styx Glacier in northern Victoria Land, Antarctica

2020 ◽  
Vol 66 (260) ◽  
pp. 916-926
Author(s):  
Yalalt Nyamgerel ◽  
Yeongcheol Han ◽  
Songyi Kim ◽  
Sang-Bum Hong ◽  
Jeonghoon Lee ◽  
...  
Keyword(s):  
Ross Sea ◽  
Accumulation Rate ◽  
Ice Core ◽  
Methanesulfonic Acid ◽  
Open Water ◽  
Water Area ◽  
Snow Accumulation ◽  
Atmospheric Conditions ◽  
Sea Ice Extent ◽  
Firn Core

AbstractUnder the potential to reconstruct the past climatic and atmospheric conditions from a deep ice core in the coastal Antarctic site (Styx Glacier), an 8.84 m long firn core (73°50.975′ S, 163°41.640′ E; 1623 m a.s.l.) was initially studied to propose a reliable age scale for the local estimation of snow accumulation rate. The seasonal variations of δ18O, methanesulfonic acid (MSA) and non-sea-salt sulfate (nssSO42–) were used for the firn core dating and revealed 25 annual peaks (from 1990 to 2014) with volcanic sulfate signal. The observed declining trend in annual accumulation rate with a mean value of 146 ± 60 kg m–2 a–1 is likely to be linked to the changes of sea-ice extent in the Ross Sea region. Moreover, the temporal variation of the annual mean δ18O, an annual flux of MSA and nssSO42– also likely to be under the influence of ice-covered and open water area. This study suggests a potential to recover past changes in an oceanic environment and will be useful for the interpretation of the long ice core drilled at the same site.

scholarly journals Methanesulfonic acid (MSA) migration in polar ice: Data synthesis and theory

2017 ◽  
Author(s):  
Matthew Osman ◽  
Sarah B. Das ◽  
Olivier Marchal ◽  
Matthew J. Evans
Keyword(s):  
Transport Model ◽  
Accumulation Rate ◽  
Ice Core ◽  
Methanesulfonic Acid ◽  
Snow Accumulation ◽  
Polar Ice ◽  
Impurity Transport ◽  
Phase Alignment ◽  
Wide Range ◽  
Soluble Impurity

Abstract. Methanesulfonic acid (MSA; CH3SO3H) in polar ice is a unique proxy of marine primary productivity, synoptic atmospheric transport, and regional sea ice behavior. However, MSA can be mobile within the firn and ice matrix, a post-depositional process that is well known but poorly understood and documented, leading to uncertainties in the integrity of the MSA paleoclimatic signal. Here, we use a compilation of 22 ice core MSA records from Greenland and Antarctica and a model of soluble impurity transport in order to comprehensively investigate the vertical migration of MSA from summer layers, where MSA is originally deposited, to adjacent winter layers in polar ice. The shallowest depths of MSA migration reported in our compilation vary over a wide range (~ 2 m to 400 m), and our analysis suggests that these depths are positively correlated with snow accumulation rate and negatively correlated with ice concentration of Na+ (typically the most abundant cationic sea salt). Although the considered soluble impurity transport model provides a useful mechanistic framework for studying MSA migration, it remains limited by inadequate constraints on key physicochemical parameters, most notably, the diffusion coefficient of MSA in cold ice (DMS). We derive a simplified version of the model, which includes DMS as the sole parameter, in order to illuminate aspects of the migration process. Using this model, we show that the progressive phase alignment of MSA and Na+ concentration peaks observed along a high-resolution West Antarctic core is most consistent with 10–12 m2 s-1 

scholarly journals An ice-core record over the last two centuries from Penny Ice Cap, Baffin Island, Canada

2002 ◽  
Vol 35 ◽  
pp. 29-35 ◽  
Author(s):  
Kumiko Goto-Azuma ◽  
Roy M. Koerner ◽  
David A. Fisher
Keyword(s):  
Environmental Changes ◽  
Ice Core ◽  
Sea Salt ◽  
Ice Age ◽  
Baffin Island ◽  
Ion Chemistry ◽  
Sea Ice Extent ◽  
The Core ◽  
Ice Cap ◽  
Ice Core Record

AbstractIn order to reconstruct climatic and environmental changes in the Canadian Arctic, an 85 m deep ice core drilled in 1995 on Penny Ice Cap, Baffin Island, was analyzed for ions and δ18O. In addition to the core, snow-pit samples collected in 1994 and 1995 were also analyzed. Elution of ions caused by summer melting was observed in the pits. Due to the heavy summer melting on this ice cap, seasonal variations of ion chemistry and δ18O were not always present in the core. Comparisons of this core with a previously reported core drilled 2.5 maway show that the noise contained in single annual time series is 40–50% for ions and 25% for δ18O. the ice-core data, however, provide us with a reasonable proxy record of climatic and environmental changes during the last two centuries on better than a decadal basis. Sulfate and nitrate concentrations started to increase around 1900 and 1960, respectively, due to anthropogenic influx transported from the industrialized regions in North America. Sea-salt concentrations began to increase around the mid-19th century and were elevated throughout the 20th century. This trend of sea-salt concentrations is similar to that of melt percentage, which is a measure of summer temperature. Warming after the Little Ice Age would have reduced the sea-ice extent and led to the elevated sea-salt concentrations on Penny Ice Cap.

scholarly journals Investigation of the 18O Content of a 100 m Ice Core From the Ronne Ice Shelf, Antarctica

1988 ◽  
Vol 10 ◽  
pp. 43-47
Author(s):  
W. Graf ◽  
O. Reinwarth ◽  
H. Moser ◽  
W. Stichler
Keyword(s):  
Flow Model ◽  
Accumulation Rate ◽  
Ice Core ◽  
Snow Accumulation ◽  
Two Dimensional ◽  
Ice Shelf ◽  
Short Term ◽  
The Core ◽  
Two Dimensional Flow ◽  
Field Season

A 100 m ice core from the Ronne Ice Shelf, drilled during the 1983-84 field season, was dated by isotopic stratigraphy, using the well-known seasonal variation in the 18O content in firn and ice; the layers at a depth of 89 m are probably 400 years old. Layer thicknesses deduced from the 18O profile indicate short-term variations of the snow-accumulation rate over the last 400 years. The area of deposition of the material recovered with the core is estimated by a two-dimensional flow model and by the 18O content of the core, which decreases from –27.5‰ in the upper part of the core to –32.0‰ at 89 m depth.

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