scholarly journals O Registro de Isótopos Estáveis de Hidrogênio em Testemunhos de Gelo da Ilha Rei George, Antártica

2000 ◽  
Vol 27 (2) ◽  
pp. 87
Author(s):  
FRANCISCO ADOLFO FERRON ◽  
JEFFERSON CARDIA SIMÕES
Keyword(s):  
Isotopic Exchange ◽  
Isotopic Fractionation ◽  
Ice Cores ◽  
Isotopic Ratios ◽  
King George Island ◽  
The West ◽  
Water Percolation ◽  
Stable Isotopic ◽  
Ice Field ◽  
The Antarctic

The hydrogen stable isotopic record in four ice cores drilled on King George Island ice field (to the west of the Antarctic Peninsula) are examined. Isotopic composition variations are strongly homogenized, exceptly in the few upper meters of cores drilled above 650-m of elevation. Intensive melting followed by water percolation throughout the snow and firn pack lead to isotopic exchange and consequently strong homogenization. A stratigraphic profile showing several ice layers and a water table detected in the glacier strengthen this hypothesis. Isotopic ratios decrease with elevation, reflecting the strong melting and isotopic fractionation in lower areas.

Ice cores and climatic change

1977 ◽  
Vol 280 (972) ◽  
pp. 143-168 ◽  
Keyword(s):  
Ice Sheets ◽  
Ice Cores ◽  
Ice Age ◽  
Isotopic Ratios ◽  
Temperature Profiles ◽  
Physical Processes ◽  
Similar Relation ◽  
Stable Isotopic ◽  
Last Ice Age ◽  
Glacial Periods

The paper deals primarily with the use of stable isotopic ratios to determine the former climate of ice sheets. Studies of temperature profiles throughout ice sheets have shown that for at least several thousand years, changes of isotopic δ ratios have been proportional to changes of surface temperatures; this relationship is discussed in terms of the physical processes involved. It is considered reasonable to use a similar relation for earlier periods in Antarctica, but in Greenland the relation may have varied with time. When determining past climates from the isotopic record, allowances have to be made for changes in the flow and thickness of ice sheets during major glacial periods. These factors are considered in relation to major ice cores from Vostok and Byrd stations in Antarctica and from Camp Century in Greenland. Vostok is the simplest case glaciologically, Camp Century the most complex. On purely glaciological grounds it appears that the ice age gave way to present-day climates some 10 000 ± 1000 a B.P., the coldest period being 20 000 + 3000 a B.P., when the climate in Antarctica was 6-8 °C colder than at present. Glaciological data suggest a duration of 50 000 to 100 000 years for the last ice age. Before this period, climates in Greenland and Antarctica appear to have been around 2-3 °C warmer than at present.

Sulphur and oxygen isotope signatures of dissolved sulphate in freshwater from King George Island, Antarctic Peninsula

2021 ◽  
pp. 1-3
Author(s):  
Yeongmin Kim ◽  
Insung Lee ◽  
Bernhard Mayer ◽  
Guebuem Kim ◽  
Jong Ik Lee ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Antarctic Peninsula ◽  
Ice Cores ◽  
Ion Concentration ◽  
King George Island ◽  
Antarctic Region ◽  
Isotopic Signatures ◽  
Natural Processes ◽  
Sulphur Cycling ◽  
The Antarctic

The sulphate ion (SO42-) is one of major species in freshwater as well as seawater, originating from various natural and anthropogenic processes (Krouse & Mayer 2000). Compared to the Northern Hemisphere, where human activities affect the sulphate concentration and isotopic signatures, the contribution of anthropogenic sulphate is likely to be negligible in freshwater and ice cores in the Antarctic region (Patris et al. 2002). This means that the sulphur and oxygen isotope compositions of the dissolved sulphate could hint at information on the sources, formation and deposition due to various natural processes and sulphur cycling in the Antarctic region, especially for the dissolved sulphate in surface waters such as ponds and creeks (Patris et al. 2000, Kim et al. 2017). Here we report the ion concentration and sulphur and oxygen isotope compositions of the dissolved sulphate in freshwater from King George Island in the Antarctic Peninsula, which provide implications regarding the sources of the dissolved sulphate and the sulphur cycling in the Antarctic region.

scholarly journals Air Temperature and Snow Accumulation in the Antarctic Peninsula During the Past 50 Years (Abstract)

1988 ◽  
Vol 11 ◽  
pp. 207-207 ◽  
Author(s):  
David A. Peel ◽  
Robert Mulvaney
Keyword(s):  
Antarctic Peninsula ◽  
Accumulation Rate ◽  
Ice Sheet ◽  
Ice Cores ◽  
Snow Accumulation ◽  
The West ◽  
Climate Type ◽  
The Past ◽  
The Antarctic ◽  
Noise Factors

Trends in climate affecting the West Antarctic ice sheet may be detected first in the Antarctic Peninsula region. Although the area contains the most comprehensive weather records for any part of Antarctica, reliable snow-accumulation data are lacking.Mainly as a result of the large snow-accumulation rate in the region (typically in the range 4.0–10.0 kg m−2 a−1), stratigraphie evidence of climate derived from ice cores can be resolved in much greater detail than is possible over most of the continent. Ice cores have been drilled at two sites, representing the extremes of climate type encountered in the region. A 133 m core has been obtained from Dolleman Island (70°35.2′S, 60°55.5′W) to represent the continental-type climate of the Weddell coast region, and an 87 m core has been obtained from the Palmer Land plateau (74°01′S, 70°38′W) to represent the more maritime regime of the west coast and central areas. Replicated cores were obtained at both sites in order to assess the contribution of local noise factors to the climatic signal preserved in the cores. Climatic trends during the period 1938–86 have been assessed on the basis of stable-isotope analysis of the top 47 m of the Palmer Land core and of the top 32 m of the Dolleman Island core.A statistical analysis of derived profiles of mean annual δ18O and accumulation rate indicates that the local noise factors at these sites are sufficiently small that data averaged over periods as short as 5 years should reveal climatic shifts at the level of 0.2% and 5% respectively. These changes are much smaller than trends that have actually occurred during the past 50 years.The most notable trend over the past 30 years is an increase of more than 30% in the snow-accumulation rate that has occurred in parallel with an overall temperature increase of 0.06°C/a during the same period. Increases of similar magnitude can be inferred from studies in East Antarctica, and may be related to a significant increase in precipitation rate that has been documented recently at mid-to high-latitude stations in the Northern Hemisphere. The finding may have relevance to studies of the possible consequences of a CO2-induced climate change. More extensive accumulation time series are now required from Antarctica, if satisfactory models of the long-term balance of the ice sheet are to be derived.

scholarly journals Air Temperature and Snow Accumulation in the Antarctic Peninsula During the Past 50 Years (Abstract)

1988 ◽  
Vol 11 ◽  
pp. 207 ◽  
Author(s):  
David A. Peel ◽  
Robert Mulvaney
Keyword(s):  
Antarctic Peninsula ◽  
Accumulation Rate ◽  
Ice Sheet ◽  
Ice Cores ◽  
Snow Accumulation ◽  
The West ◽  
Climate Type ◽  
The Past ◽  
The Antarctic ◽  
Noise Factors

Trends in climate affecting the West Antarctic ice sheet may be detected first in the Antarctic Peninsula region. Although the area contains the most comprehensive weather records for any part of Antarctica, reliable snow-accumulation data are lacking. Mainly as a result of the large snow-accumulation rate in the region (typically in the range 4.0–10.0 kg m−2 a−1), stratigraphie evidence of climate derived from ice cores can be resolved in much greater detail than is possible over most of the continent. Ice cores have been drilled at two sites, representing the extremes of climate type encountered in the region. A 133 m core has been obtained from Dolleman Island (70°35.2′S, 60°55.5′W) to represent the continental-type climate of the Weddell coast region, and an 87 m core has been obtained from the Palmer Land plateau (74°01′S, 70°38′W) to represent the more maritime regime of the west coast and central areas. Replicated cores were obtained at both sites in order to assess the contribution of local noise factors to the climatic signal preserved in the cores. Climatic trends during the period 1938–86 have been assessed on the basis of stable-isotope analysis of the top 47 m of the Palmer Land core and of the top 32 m of the Dolleman Island core. A statistical analysis of derived profiles of mean annual δ18O and accumulation rate indicates that the local noise factors at these sites are sufficiently small that data averaged over periods as short as 5 years should reveal climatic shifts at the level of 0.2% and 5% respectively. These changes are much smaller than trends that have actually occurred during the past 50 years. The most notable trend over the past 30 years is an increase of more than 30% in the snow-accumulation rate that has occurred in parallel with an overall temperature increase of 0.06°C/a during the same period. Increases of similar magnitude can be inferred from studies in East Antarctica, and may be related to a significant increase in precipitation rate that has been documented recently at mid-to high-latitude stations in the Northern Hemisphere. The finding may have relevance to studies of the possible consequences of a CO2-induced climate change. More extensive accumulation time series are now required from Antarctica, if satisfactory models of the long-term balance of the ice sheet are to be derived.

scholarly journals Photolytic control of the nitrate stable isotope signal in snow and atmosphere of East Antarctica and implications for reactive nitrogen cycling

2009 ◽  
Vol 9 (3) ◽  
pp. 12559-12596 ◽  
Author(s):  
M. M. Frey ◽  
J. Savarino ◽  
S. Morin ◽  
J. Erbland ◽  
J. M. F. Martins
Keyword(s):  
Isotopic Exchange ◽  
Isotopic Fractionation ◽  
Ice Cores ◽  
Skin Layer ◽  
Reactive Nitrogen ◽  
Lab Experiments ◽  
15N Enrichment ◽  
Oxygen Stable Isotopes ◽  
Significant Enrichment ◽  
Isotopic Signal

Abstract. The nitrogen (δ15N) and triple oxygen (δ17/18O) isotopic composition of nitrate (NO3−) was measured year-round in the atmosphere and snow pits at Dome C (DC, 75.1° S, 123.3° E), and in surface snow on a transect between DC and the coast. Snow pit profiles of δ15N (δ18O) in NO3− show significant enrichment (depletion) of >200 (<40) ‰ compared to the isotopic signal in atmospheric NO3−, whereas post-depositional fractionation in Δ17O(NO3−) is small, allowing reconstruction of past shifts in tropospheric oxidation pathways from ice cores. Assuming a Rayleigh-type process we find in the DC04 (DC07) pit fractionation factors ε of −50±10 (−71±12) ‰, 6±3 (9±2) ‰ and 1±0.2 (2±0.6) ‰, for δ15N, δ18O and Δ17O, respectively. A photolysis model reproduces ε for δ15N within the range of uncertainty at DC and for lab experiments reported by Blunier et al. (2005), suggesting that the current literature value for photolytic isotopic fractionation in snow is significantly underestimated. Depletion of oxygen stable isotopes is attributed to photolysis followed by isotopic exchange with water and hydroxyl radicals. Conversely, 15N enrichment of the NO3− fraction in the snow implies 15N depletion of emissions. Indeed, δ15N in atmospheric NO3− shows a strong decrease from background levels (4.4±6.8‰) to −35.1‰ in spring followed by recovery during summer, consistent with significant snow pack emissions of reactive nitrogen. Field and lab evidence therefore suggest that photolysis dominates fractionation and associated NO3− loss from snow in the low-accumulation regions of the East Antarctic Ice Sheet (EAIS). The Δ17O signature confirms previous coastal measurements that the peak of atmospheric NO3− in spring is of stratospheric origin. After sunrise photolysis drives then redistribution of NO3− from the snowpack photic zone to the atmosphere and a snow surface skin layer, thereby concentrating NO3− at the surface. Little NO3− is exported off the EAIS plateau, still snow emissions from as far as 600 km inland can contribute to the coastal NO3− budget.

scholarly journals High-resolution ice-core stable-isotopic records from Antarctica: towards interannual climate reconstruction

2005 ◽  
Vol 41 ◽  
pp. 63-70 ◽  
Author(s):  
David P. Schneider ◽  
Eric J. Steig ◽  
Tas Van Ommen
Keyword(s):  
Large Scale ◽  
Ice Core ◽  
Multiple Linear Regression Model ◽  
Ice Cores ◽  
The United States ◽  
Seasonal Temperature ◽  
Stable Isotopic ◽  
Isotopic Records ◽  
The Antarctic ◽  
Ice Core Records

AbstractIce-core records are a key resource for reconstructing Antarctic climate. However, a number of physical processes preclude the simple interpretation of ice-core properties such as oxygen isotopic ratios in terms of climate variables like temperature or sea-level pressure. We show that well-dated, sub-annually resolved stable-isotopic records from the United States International Trans-Antarctic Scientific Expedition (US-ITASE) traverses and other sources have a high correlation with local seasonal temperature variation. However, this temporal relationship cannot be simply extended to quantitative interannual resolution reconstructions of site temperature. We suggest that a consistent and important target for ice-core calibrations is a composite of annual mean temperature records from Antarctic weather stations, which covaries strongly with the dominant mode (from principal component analysis) of temperature variability in the Antarctic. Significant correlations with this temperature index are found with individual ice-core records, with a composite of the ice cores, and through a multiple linear regression model with the ice cores as predictors. These results imply that isotopic signals, like the instrumental temperature mode itself, have a strong response to large-scale atmospheric circulation variability, which in the Antarctic region is dominated by the Southern Annular Mode.

scholarly journals Quantum Genetic Terrain Algorithm (Q-GTA): A Technique to Study the Evolution of the Earth Using Quantum Genetic Algorithm

Proceedings ◽  
2019 ◽  
Vol 46 (1) ◽  
pp. 26
Author(s):  
Pranjal Sharma ◽  
Ankit Agarwal ◽  
Bhawna Chaudhary
Keyword(s):  
Genetic Algorithm ◽  
Isotopic Fractionation ◽  
Volcanic Eruptions ◽  
Temperature Characteristic ◽  
Isotopic Ratios ◽  
Mantle Lithosphere ◽  
Monitoring Networks ◽  
Temperature Changes ◽  
Quantum Genetic Algorithm ◽  
The Earth

In recent years, geologists have put in a lot of effort trying to study the evolution of Earth using different techniques studying rocks, gases, and water at different channels like mantle, lithosphere, and atmosphere. Some of the methods include estimation of heat flux between the atmosphere and sea ice, modeling global temperature changes, and groundwater monitoring networks. That being said, algorithms involving the study of Earth’s evolution have been a debated topic for decades. In addition, there is distinct research on the mantle, lithosphere, and atmosphere using isotopic fractionation, which this paper will take into consideration to form genes at the former stage. This factor of isotopic fractionation could be molded in QGA to study the Earth’s evolution. We combined these factors because the gases containing these isotopes move from mantle to lithosphere or atmosphere through gaps or volcanic eruptions contributing to it. We are likely to use the Rb/Sr and Sm/Nd ratios to study the evolution of these channels. This paper, in general, provides the idea of gathering some information about temperature changes by using isotopic ratios as chromosomes, in QGA the chromosomes depict the characteristic of a generation. Here these ratios depict the temperature characteristic and other steps of QGA would be molded to study these ratios in the form of temperature changes, which would further signify the evolution of Earth based on the study that temperature changes with the change in isotopic ratios. This paper will collect these distinct studies and embed them into an upgraded quantum genetic algorithm called Quantum Genetic Terrain Algorithm or Quantum GTA.

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