Classroom Antarctica

Science.gov (United States)

Gozzard, David

2017-01-01

Australian company Antarctica Flights runs summer sightseeing trips out of Australian capital cities to tour the Antarctic coast. The Laby Foundation of the University of Melbourne, through its "Classroom Antarctica" program, sponsored Kent Street High School science teacher, Ms Suzy Urbaniak and 18 of her students to take the trip, to…

GENOTOXICITY OF SHALLOW WATERS NEAR THE BRAZILIAN ANTARCTIC STATION "COMANDANTE FERRAZ" (EACF, ADMIRALTY BAY, KING GEORGE ISLAND, ANTARCTICA

Directory of Open Access Journals (Sweden)

Arthur José da Silva Rocha

2015-03-01

Full Text Available Series of biomonitoring surveys were undertaken weekly in February 2012 to investigate the genotoxicity of the shallow waters around the Brazilian Antarctic Station "Comandante Ferraz" (EACF. The comet assay was applied to assess the damage to the DNA of hemocytes of the crustacean amphipods Gondogeneia antarctica collected from shallow waters near the Fuel Tanks (FT and Sewage Treatment Outflow (STO of the research station, and compare it to the DNA damage of animals from Punta Plaza (PPL and Yellow Point (YP, natural sites far from the EACF defined as experimental controls. The damage to the DNA of hemocytes of G. antarctica was not significantly different between sites in the biomonitoring surveys I and II. In survey III, the damage to the DNA of animals captured in shallow waters near the Fuel Tanks (FT and Sewage Treatment Outflow (STO was significantly higher than that of the control site of Punta Plaza (PPL. In biomonitoring survey IV, a significant difference was detected only between the FT and PPL sites. Results demonstrated that the shallow waters in front of the station may be genotoxic and that the comet assay and hemocytes of G. antarctica are useful tools for assessing genotoxicity in biomonitoring studies of Antarctic marine coastal habitats.

Ice recrystallization inhibition proteins (IRIPs) and freeze tolerance in the cryophilic Antarctic hair grass Deschampsia antarctica E. Desv.

Science.gov (United States)

John, Ulrik P; Polotnianka, Renatam M; Sivakumaran, Kailayapillai A; Chew, Orinda; Mackin, Leanne; Kuiper, Micheal J; Talbot, Jonathan P; Nugent, Gregory D; Mautord, Julie; Schrauf, Gustavo E; Spangenberg, German C

2009-04-01

Antarctic hair grass (Deschampsia antarctica E. Desv.), the only grass indigenous to Antarctica, has well-developed freezing tolerance, strongly induced by cold acclimation. Here, we show that in response to low temperatures, D. antarctica expresses potent recrystallization inhibition (RI) activity that, inhibits the growth of small ice crystals into potentially damaging large ones, is proteinaceous and localized to the apoplasm. A gene family from D. antarctica encoding putative homologs of an ice recrystallization inhibition protein (IRIP) has been isolated and characterized. IRIPs are apoplastically targeted proteins with two potential ice-binding motifs: 1-9 leucine-rich repeats (LRRs) and c. 16 'IRIP' repeats. IRIP genes appear to be confined to the grass subfamily Pooideae and their products, exhibit sequence similarity to phytosulphokine receptors and are predicted to adopt conformations with two ice-binding surfaces. D. antarctica IRIP (DaIRIP) transcript levels are greatly enhanced in leaf tissue following cold acclimation. Transgenic Arabidopsis thaliana expressing a DaIRIP has novel RI activity, and purified DaIRIP, when added back to extracts of leaves from non-acclimated D. antarctica, can reconstitute the activity found in acclimated plants. We propose that IRIP-mediated RI activity may contribute to the cryotolerance of D. antarctica, and thus to its unique ability to have colonized Antarctica.

Combined Gravimetric-Seismic Crustal Model for Antarctica

Science.gov (United States)

Baranov, Alexey; Tenzer, Robert; Bagherbandi, Mohammad

2018-01-01

The latest seismic data and improved information about the subglacial bedrock relief are used in this study to estimate the sediment and crustal thickness under the Antarctic continent. Since large parts of Antarctica are not yet covered by seismic surveys, the gravity and crustal structure models are used to interpolate the Moho information where seismic data are missing. The gravity information is also extended offshore to detect the Moho under continental margins and neighboring oceanic crust. The processing strategy involves the solution to the Vening Meinesz-Moritz's inverse problem of isostasy constrained on seismic data. A comparison of our new results with existing studies indicates a substantial improvement in the sediment and crustal models. The seismic data analysis shows significant sediment accumulations in Antarctica, with broad sedimentary basins. According to our result, the maximum sediment thickness in Antarctica is about 15 km under Filchner-Ronne Ice Shelf. The Moho relief closely resembles major geological and tectonic features. A rather thick continental crust of East Antarctic Craton is separated from a complex geological/tectonic structure of West Antarctica by the Transantarctic Mountains. The average Moho depth of 34.1 km under the Antarctic continent slightly differs from previous estimates. A maximum Moho deepening of 58.2 km under the Gamburtsev Subglacial Mountains in East Antarctica confirmed the presence of deep and compact orogenic roots. Another large Moho depth in East Antarctica is detected under Dronning Maud Land with two orogenic roots under Wohlthat Massif (48-50 km) and the Kottas Mountains (48-50 km) that are separated by a relatively thin crust along Jutulstraumen Rift. The Moho depth under central parts of the Transantarctic Mountains reaches 46 km. The maximum Moho deepening (34-38 km) in West Antarctica is under the Antarctic Peninsula. The Moho depth minima in East Antarctica are found under the Lambert Trench (24

Redescription of Oswaldella antarctica (Jäderholm, 1904) (Cnidaria Hydrozoa) with notes on related species (Notes on Antarctic hydroids, I)

NARCIS (Netherlands)

Peña Cantero, A.L.; Vervoort, W.

1995-01-01

Jäderholm's type of Schizotricha antarctica, collected by the Swedish Antarctic Expedition 1901-1903, is redescribed from a syntype in the collections of the Swedish National Museum, Stockholm. The type lot of that species proved to be composite, the material best resembling Jäderholm's (1904, 1905)

New Antarctic Gravity Anomaly Grid for Enhanced Geodetic and Geophysical Studies in Antarctica.

Science.gov (United States)

Scheinert, M; Ferraccioli, F; Schwabe, J; Bell, R; Studinger, M; Damaske, D; Jokat, W; Aleshkova, N; Jordan, T; Leitchenkov, G; Blankenship, D D; Damiani, T M; Young, D; Cochran, J R; Richter, T D

2016-01-28

Gravity surveying is challenging in Antarctica because of its hostile environment and inaccessibility. Nevertheless, many ground-based, airborne and shipborne gravity campaigns have been completed by the geophysical and geodetic communities since the 1980s. We present the first modern Antarctic-wide gravity data compilation derived from 13 million data points covering an area of 10 million km 2 , which corresponds to 73% coverage of the continent. The remove-compute-restore technique was applied for gridding, which facilitated levelling of the different gravity datasets with respect to an Earth Gravity Model derived from satellite data alone. The resulting free-air and Bouguer gravity anomaly grids of 10 km resolution are publicly available. These grids will enable new high-resolution combined Earth Gravity Models to be derived and represent a major step forward towards solving the geodetic polar data gap problem. They provide a new tool to investigate continental-scale lithospheric structure and geological evolution of Antarctica.

New Antarctic Gravity Anomaly Grid for Enhanced Geodetic and Geophysical Studies in Antarctica

Science.gov (United States)

Scheinert, M.; Ferraccioli, F.; Schwabe, J.; Bell, R.; Studinger, M.; Damaske, D.; Jokat, W.; Aleshkova, N.; Jordan, T.; Leitchenkov, G.; Blankenship, D. D.; Damiani, T. M.; Young, D.; Cochran, J. R.; Richter, T. D.

2018-01-01

Gravity surveying is challenging in Antarctica because of its hostile environment and inaccessibility. Nevertheless, many ground-based, airborne and shipborne gravity campaigns have been completed by the geophysical and geodetic communities since the 1980s. We present the first modern Antarctic-wide gravity data compilation derived from 13 million data points covering an area of 10 million km2, which corresponds to 73% coverage of the continent. The remove-compute-restore technique was applied for gridding, which facilitated levelling of the different gravity datasets with respect to an Earth Gravity Model derived from satellite data alone. The resulting free-air and Bouguer gravity anomaly grids of 10 km resolution are publicly available. These grids will enable new high-resolution combined Earth Gravity Models to be derived and represent a major step forward towards solving the geodetic polar data gap problem. They provide a new tool to investigate continental-scale lithospheric structure and geological evolution of Antarctica. PMID:29326484

Beryllium-7 in Usnea antarctica Du Rietz from the Machu Picchu Antarctic Research Station

International Nuclear Information System (INIS)

Osores, Jose; Gonzales, Susana

2013-01-01

Concentrations of Be-7 in Usnea antarctica (lichen) collected during the austral summer of 2013 in the Antarctic Scientific Station 'Machu Picchu' were determined by high resolution gamma spectrometry, obtaining values between 366.5 and 515.1 Becquerels per kilogram dry weight. The analysis of variance shows no significant difference in the concentrations of Be-7 between sampling areas located at different heights. The average value of Be-7 for 2013 is significantly higher to other sampling years, except for 1996. (authors).

Transcriptomic response of the Antarctic pteropod Limacina helicina antarctica to ocean acidification.

Science.gov (United States)

Johnson, Kevin M; Hofmann, Gretchen E

2017-10-23

Ocean acidification (OA), a change in ocean chemistry due to the absorption of atmospheric CO 2 into surface oceans, challenges biogenic calcification in many marine organisms. Ocean acidification is expected to rapidly progress in polar seas, with regions of the Southern Ocean expected to experience severe OA within decades. Biologically, the consequences of OA challenge calcification processes and impose an energetic cost. In order to better characterize the response of a polar calcifier to conditions of OA, we assessed differential gene expression in the Antarctic pteropod, Limacina helicina antarctica. Experimental levels of pCO 2 were chosen to create both contemporary pH conditions, and to mimic future pH expected in OA scenarios. Significant changes in the transcriptome were observed when juvenile L. h. antarctica were acclimated for 21 days to low-pH (7.71), mid-pH (7.9) or high-pH (8.13) conditions. Differential gene expression analysis of individuals maintained in the low-pH treatment identified down-regulation of genes involved in cytoskeletal structure, lipid transport, and metabolism. High pH exposure led to increased expression and enrichment for genes involved in shell formation, calcium ion binding, and DNA binding. Significant differential gene expression was observed in four major cellular and physiological processes: shell formation, the cellular stress response, metabolism, and neural function. Across these functional groups, exposure to conditions that mimic ocean acidification led to rapid suppression of gene expression. Results of this study demonstrated that the transcriptome of the juvenile pteropod, L. h. antarctica, was dynamic and changed in response to different levels of pCO 2 . In a global change context, exposure of L. h. antarctica to the low pH, high pCO 2 OA conditions resulted in a suppression of transcripts for genes involved in key physiological processes: calcification, metabolism, and the cellular stress response. The

Geoologic controls on the architecture of the Antarctic Ice Sheet's basal interface: New results from West and East Antarctica from long range geophysics (Invited)

Science.gov (United States)

Young, D. A.; Blankenship, D. D.; Greenbaum, J. S.; Richter, T.; Aitken, A.; Siegert, M. J.; Roberts, J. L.

2013-12-01

The ice-rock interface underlying the Antarctic Ice Sheet was shaped by interactions between underlying gondwanan geology and the overlying ice sheet. The ice sheet now preserves from sedimentary infill an incredibly rugged terrain which now plays a critical role in shaping subglacial hydrology, and thus shape ice sheet behavior. This terrain can by imaged through aerogeophysical means, in particular through ice penetrating radar, while airborne potential fields measurements provide insight into the geological framework that controlled erosion. Over the post IPY era, the density of airborne coverage is only now reaching the point where small scale structure can be identified and placed in context. Of particular importance is understanding the formation of focused erosional valleys, 30-50 km wide, representing now buried subglacial fjords. After initial data from the GIMBLE project in West Antarctica, and five years of sustained long range ICECAP surveys over East Antarctica , we now have a better view of the diversity of these features. The local erosion of these valleys, often cutting through significant topographic barriers, irregularly samples the underlying geology, provided a complex story in the sediment to the Antarctic margin. These valleys now provide the subglacial conduits for significant ice sheet catchments, in particular for subglacial water, including the inland catchments of DeVicq, Thwaites, and Pine Island Glaciers in West Antarctica, and Denman Glacier, Totten Glacier, Byrd Glacier and Cook Ice Shelf in East Antarctica. We find that these features, now sometimes hundreds of kilometers inland of the modern grounding line, often nucleate on or are aligned with structure inherited from the assembly of the Antarctic continent. While many of these features currently host active outlet glaciers or their tributaries, some do not, implying avenues for ice sheet change. In West Antarctica, we find a new deep connection between the coast and interior basin

Persistent Organic Pollutants in Biotic and Abiotic Components of Antarctic Pristine Environment

Science.gov (United States)

Bhardwaj, Laxmikant; Chauhan, Abhishek; Ranjan, Anuj; Jindal, Tanu

2018-05-01

Over the past decades, research in Antarctica has built a new understanding of Antarctica, its past, present and future. Human activities and long-range pollutants are increasing on the Antarctic continent. Research on persistent organic pollutants (POPs) has been carried out internationally by several countries having their permanent research stations to explain the impact of an ever increasing range of POPs in Antarctic ecosystem. POPs have been detected in Antarctica despite its geographical isolation and almost complete absence of human settlements. The presence of POPs in different abiotic (atmosphere, water bodies, sediments, soil, sea ice) and biotic components (mosses, lichens, krill, penguins, skua, etc.) in Antarctica has been studied and documented around for decades and has either been banned or strictly regulated but is still found in the environment. This review focuses on recent research pertaining to sources and occurrence of POPs in Antarctic lake water, soil, sediment, lichen, mosses and other Antarctic marine community. This review also proposes to summarize the current state of research on POPs in Antarctica environment and draw the earliest conclusions on possible significance of POPs in Antarctica based on presently available information from related Antarctic environment.

Antarctic glossopterid diversity on a local scale: the presence of multiple megasporophyll genera, Upper Permian, Mt. Achernar, Transantarctic Mountains, Antarctica.

Science.gov (United States)

Ryberg, Patricia E; Taylor, Edith L; Taylor, Thomas N

2012-09-01

The glossopterids are a group of plants that thrived during a time of global warming similar to what is happening on the Earth today as well as the transition from archaic plant groups to the ancestors of modern groups. The diversity of the glossopterid clade is based on the megasporangiate structures assigned to the group, because the vegetative and pollen-bearing structures vary little. The presence of numerous reproductive genera from a single Upper Permian locality in the central Transantarctic Mountains provides important data on local glossopterid diversity in Antarctica. Impression/compression fossils were imaged with a Leica 5000C digital camera on a dissecting microscope or a Fujifilm FinePix S1pro digital camera. Two megasporangiate taxa are described: Scutum leiophyllum, which represents the first confirmed record of the genus in Antarctica, and Lidgettoniopsis ramulus, a new morphology consisting of a pinnate structure with oppositely attached megasporophylls. Plumsteadia ovata specimens indicate that this genus can be larger than previously recorded and illustrate the vegetative surface with a distinct midrib. The presence of a laminar, multiovulate structure and a pinnate structure at the same site indicates that local-level glossopterid diversity in Antarctica is greater than previously hypothesized. The discovery of a new megasporophyll morphology in Antarctica (confirming the presence of three distinctive morphologies on the continent) shows that Antarctic glossopterid heterogeneity is on a par with other Gondwanan continents. The diversity of the Antarctic landscape reveals that high polar latitudes can sustain a diverse ecosystem during times of global warming.

Bacterial diversity in rhizosphere soil from Antarctic vascular plants of Admiralty Bay, maritime Antarctica.

Science.gov (United States)

Teixeira, Lia C R S; Peixoto, Raquel S; Cury, Juliano C; Sul, Woo Jun; Pellizari, Vivian H; Tiedje, James; Rosado, Alexandre S

2010-08-01

The Antarctic is a pristine environment that contributes to the maintenance of the global climate equilibrium. The harsh conditions of this habitat are fundamental to selecting those organisms able to survive in such an extreme habitat and able to support the relatively simple ecosystems. The DNA of the microbial community associated with the rhizospheres of Deschampsia antarctica Desv (Poaceae) and Colobanthus quitensis (Kunth) BartI (Caryophyllaceae), the only two native vascular plants that are found in Antarctic ecosystems, was evaluated using a 16S rRNA multiplex 454 pyrosequencing approach. This analysis revealed similar patterns of bacterial diversity between the two plant species from different locations, arguing against the hypothesis that there would be differences between the rhizosphere communities of different plants. Furthermore, the phylum distribution presented a peculiar pattern, with a bacterial community structure different from those reported of many other soils. Firmicutes was the most abundant phylum in almost all the analyzed samples, and there were high levels of anaerobic representatives. Also, some phyla that are dominant in most temperate and tropical soils, such as Acidobacteria, were rarely found in the analyzed samples. Analyzing all the sample libraries together, the predominant genera found were Bifidobacterium (phylum Actinobacteria), Arcobacter (phylum Proteobacteria) and Faecalibacterium (phylum Firmicutes). To the best of our knowledge, this is the first major bacterial sequencing effort of this kind of soil, and it revealed more than expected diversity within these rhizospheres of both maritime Antarctica vascular plants in Admiralty Bay, King George Island, which is part of the South Shetlands archipelago.

Regional genetic diversity patterns in Antarctic hairgrass (Deschampsia antartica Desv.)

NARCIS (Netherlands)

van de Wouw, M.J.; Van Dijk, P.J.; Huiskes, A.H.L.

2008-01-01

Aim To determine patterns in diversity of a major Antarctic plant species, including relationships of Antarctic populations with those outside the Antarctic zone. Location Antarctic Peninsula, Maritime Antarctica, sub-Antarctic islands, Falkland Islands and South America. Methods Amplified fragment

Antarctic crabs: invasion or endurance?

Directory of Open Access Journals (Sweden)

Huw J Griffiths

Full Text Available Recent scientific interest following the "discovery" of lithodid crabs around Antarctica has centred on a hypothesis that these crabs might be poised to invade the Antarctic shelf if the recent warming trend continues, potentially decimating its native fauna. This "invasion hypothesis" suggests that decapod crabs were driven out of Antarctica 40-15 million years ago and are only now returning as "warm" enough habitats become available. The hypothesis is based on a geographically and spatially poor fossil record of a different group of crabs (Brachyura, and examination of relatively few Recent lithodid samples from the Antarctic slope. In this paper, we examine the existing lithodid fossil record and present the distribution and biogeographic patterns derived from over 16,000 records of Recent Southern Hemisphere crabs and lobsters. Globally, the lithodid fossil record consists of only two known specimens, neither of which comes from the Antarctic. Recent records show that 22 species of crabs and lobsters have been reported from the Southern Ocean, with 12 species found south of 60 °S. All are restricted to waters warmer than 0 °C, with their Antarctic distribution limited to the areas of seafloor dominated by Circumpolar Deep Water (CDW. Currently, CDW extends further and shallower onto the West Antarctic shelf than the known distribution ranges of most lithodid species examined. Geological evidence suggests that West Antarctic shelf could have been available for colonisation during the last 9,000 years. Distribution patterns, species richness, and levels of endemism all suggest that, rather than becoming extinct and recently re-invading from outside Antarctica, the lithodid crabs have likely persisted, and even radiated, on or near to Antarctic slope. We conclude there is no evidence for a modern-day "crab invasion". We recommend a repeated targeted lithodid sampling program along the West Antarctic shelf to fully test the validity of the

CEDEX research activities in Antarctica. Aquatic ecosystems in Byers Peninsula (Livingston Island, maritime Antarctica)

International Nuclear Information System (INIS)

Toro, M.; Quesada, A.; Camacho, A.; Oliva, M.; Alcami, A.; Antoniades, D.; Banon, M.; Fassnacht, S.; Fernandez-Valiente, E.; Galan, L.; Giralt, S.; Granados, I.; Justel, A.; Liu, E. J.; Lopez-Bravo, A.; Martinez-Cortizas, A.; Pla-Rabes, S.; Rastrojo, A.; Rico, E.; Rochera, C.; Van de Vijver, B.; Velazquez, D.; Villaescusa, J. A.; Vicent, W. F.

2015-01-01

Since 2001 CEDEX has taken part in many Antarctic joint research projects with different institutions from Spain and other countries, developing scientific activities in the International Camp of Byers Peninsular (Livingston Island, South Shetland Islands, Antarctica). This place was designed as an Antarctic Specially Protected Area (No.126) because the importance and value of its terrestrial and aquatic habitats. It is one of the largest ice-free areas of maritime Antarctica, with the highest diversity of environments and geological, hydrological and biological processes in the whole region, all of them in a pristine state. Byers Peninsula is considered the most significant limnological area in the Antarctic Peninsula region because it hosts a high number of lakes, ponds and streams, with an exceptional fauna and flora diversity, including the most singular, representative or endemic Antarctic species. Furthermore, the lakes sedimentary record is one of the widest and complete archives in Antarctic Peninsula region for the palaeocological and climatic study of the Holocene. Because Byers Peninsula is an Antarctic biodiversity hotspot, and it is located in one of the areas in the Earth where global warming is being more significant, it must be considered as a suitable international reference site for limnetic, terrestrial and coastal studies, and long term monitoring programmes. (Author)

Meteorites, Ice, and Antarctica

Science.gov (United States)

Cassidy, William A.

2003-08-01

Bill Cassidy led meteorite recovery expeditions in the Antarctic for fifteen years and his searches have resulted in the collection of thousands of meteorite specimens from the ice. This personal account of his field experiences on the U.S. Antarctic Search for Meteorites Project reveals the influence the work has had on our understanding of the moon, Mars and the asteroid belt. Cassidy describes the hardships and dangers of fieldwork in a hostile environment, as well as the appreciation he developed for its beauty. William Cassidy is Emeritus Professor of Geology and Planetary Science at the University of Pittsburgh. He initiated the U.S. Antarctic Search for Meteorites (ANSMET) nroject and led meteorite recovery expeditions in Antarctica in1976. His name is found attached to a mineral (cassidyite), on the map of Antarctica (Cassidy Glacier), and in the Catalog of Asteroids (3382 Cassidy). Profiled in "American Men of Science," and "Who's Who in America," he is also a recipient of The Antarctic Service Medal from the United States and has published widely in Science, Meteoritics and Planetary Science, and The Journal of Geophysical Research.

Application of a quantitative histological health index for Antarctic rock cod (Trematomus bernacchii) from Davis Station, East Antarctica.

Science.gov (United States)

Corbett, Patricia A; King, Catherine K; Mondon, Julie A

2015-08-01

A quantitative Histological Health Index (HHI) was applied to Antarctic rock cod (Trematomus bernacchii) using gill, liver, spleen, kidney and gonad to assess the impact of wastewater effluent from Davis Station, East Antarctica. A total of 120 fish were collected from 6 sites in the Prydz Bay region of East Antarctica at varying distances from the wastewater outfall. The HHI revealed a greater severity of alteration in fish at the wastewater outfall, which decreased stepwise with distance. Gill and liver displayed the greatest severity of alteration in fish occurring in close proximity to the wastewater outfall, showing severe and pronounced alteration respectively. Findings of the HHI add to a growing weight of evidence indicating that the current level of wastewater treatment at Davis Station is insufficient to prevent impact to the surrounding environment. The HHI for T. bernacchii developed in this study is recommended as a useful risk assessment tool for assessing in situ, sub-lethal impacts from station-derived contamination in coastal regions throughout Antarctica. Copyright © 2015 Elsevier Ltd. All rights reserved.

Trace-element analysis of Antarctic H chondrites: Chemical weathering and comparisons with their non-Antarctic counterparts

International Nuclear Information System (INIS)

Kwok, J.E.

1986-01-01

Large numbers of meteorites have been discovered in Antarctica over the last decade (7000 fragments probably representing over 1200 separate events). They are important for their numbers and for their complement of unique or rare specimens; they also have long terrestrial ages (up to 1,000,000 years) compared to non-Antarctic falls (usually < 200 years). We report compositional data for mobile/volatile trace elements Ag, Au, Bi, Cd, Co, Cs, In, Rb, Sb, Se, Te, Ti, U, and Zn in a suite of Antarctic H chondrites. Our data show that heavily oxidized H chondrites are leached of a portion of their trace elements and, therefore, have been chemically compromised by their stay in Antarctica. The less oxidized specimens seem to have retained their chemical integrity. We suggest possibilities for using chemical data to measure the degree of a chondrite's chemical weathering. We compare our data to that obtained previously for non-Antarctic H chondrites (Linger et al., 1986), by petrologic type (H4, H5, H6, H4-6) and shock-loading (moderately shocked facies a-c, heavily shocked facies d-f). Many statistically significant differences are found between non-Antarctic and Victoria Land, Antarctica H chondrites of each petrologic type and of shock facies d-f

Autumn Cooling of Western East Antarctica Linked to the Tropical Pacific

Science.gov (United States)

Clem, Kyle R.; Renwick, James A.; McGregor, James

2018-01-01

Over the past 60 years, the climate of East Antarctica cooled while portions of West Antarctica were among the most rapidly warming regions on the planet. The East Antarctic cooling is attributed to a positive trend in the Southern Annular Mode (SAM) and a strengthening of the westerlies, while West Antarctic warming is tied to zonally asymmetric circulation changes forced by the tropics. This study finds recent (post-1979) surface cooling of East Antarctica during austral autumn to also be tied to tropical forcing, namely, an increase in La Niña events. The recent increase in La Niña conditions forces a Rossby wave into the Southern Hemisphere that increases anticyclonic circulation over the South Atlantic. The South Atlantic anticyclone is associated with cold air advection, weakened northerlies, and increased sea ice concentrations across the western East Antarctic coast, which has increased the rate of cooling at Novolazarevskaya and Syowa stations after 1979. This enhanced cooling over western East Antarctica is tied more broadly to a zonally asymmetric temperature trend pattern across East Antarctica during autumn that is consistent with a tropically forced Rossby wave rather than a SAM pattern; the positive SAM pattern is associated with ubiquitous cooling across East Antarctica, which is not seen in temperature observations after 1979. We conclude that El Niño-Southern Oscillation-related circulation anomalies, particularly zonal asymmetries that locally enhance meridional wind, are an important component of East Antarctic climate variability during autumn, and future changes in tropical Pacific climate will likely have implications for East Antarctica.

Shifting baselines in Antarctic ecosystems; ecophysiological response to warming in Lissarca miliaris at Signy Island, Antarctica.

Science.gov (United States)

Reed, Adam J; Thatje, Sven; Linse, Katrin

2012-01-01

The Antarctic Peninsula has experienced a rapid increase in atmospheric temperature over the last 50 years. Whether or not marine organisms thriving in this cold stenothermal environment are able to cope with warming is of concern. Here, we present changes to the growth and shell characteristics of the ecologically important, small and short lived brooding bivalve Lissarca miliaris from Signy Island, Antarctica. Using material collected from the 1970's to the present day, we show an increase in growth rate and adult shell deterioration accompanied by a decrease in offspring size, associated with an increase in annual average temperatures. Critical changes to the bivalve's ecology seen today evidence the problem of a shift in baseline since the onset of warming recorded in Antarctica. These small bivalves are demonstrating ecophysiological responses to subtle warming that, provided warming continues, could soon surpass a physiological tipping point, adding to warming associated threats such as increased predatory pressure and ocean acidification.

Shifting baselines in Antarctic ecosystems; ecophysiological response to warming in Lissarca miliaris at Signy Island, Antarctica.

Directory of Open Access Journals (Sweden)

Adam J Reed

Full Text Available The Antarctic Peninsula has experienced a rapid increase in atmospheric temperature over the last 50 years. Whether or not marine organisms thriving in this cold stenothermal environment are able to cope with warming is of concern. Here, we present changes to the growth and shell characteristics of the ecologically important, small and short lived brooding bivalve Lissarca miliaris from Signy Island, Antarctica. Using material collected from the 1970's to the present day, we show an increase in growth rate and adult shell deterioration accompanied by a decrease in offspring size, associated with an increase in annual average temperatures. Critical changes to the bivalve's ecology seen today evidence the problem of a shift in baseline since the onset of warming recorded in Antarctica. These small bivalves are demonstrating ecophysiological responses to subtle warming that, provided warming continues, could soon surpass a physiological tipping point, adding to warming associated threats such as increased predatory pressure and ocean acidification.

Antarctic science

Science.gov (United States)

Summerhayes, Colin

Once upon a time, dinosaurs roamed Antarctica and swam in its seas. Since then, life evolved as the climate cooled into the ice ages. Life will no doubt continue to evolve there as the globe now warms. But nowadays, humans are having a profound and direct effect on life in Antarctica, the sub-Antarctic islands, and the surrounding Southern Ocean, which are being invaded by a wide range of alien species including microbes, algae, fungi, bryophytes, land plants, invertebrates, fish, birds, and mammals.

Antarctic news clips, 1991

Science.gov (United States)

1991-08-01

Published stories are presented that sample a year's news coverage of Antarctica. The intent is to provide the U.S. Antarctic Program participants with a digest of current issues as presented by a variety of writers and popular publications. The subject areas covered include the following: earth science; ice studies; stratospheric ozone; astrophysics; life science; operations; education; antarctic treaty issues; and tourism

Radon in Antarctica

International Nuclear Information System (INIS)

Ilic, R.; Rusov, V.D.; Pavlovych, V.N.; Vaschenko, V.M.; Hanzic, L.; Bondarchuk, Y.A.

2005-01-01

The paper reviews results of radon measurements obtained in Antarctic research stations in the last 40 years by both active and passive radon monitors. A brief description of the radon laboratory set-up in the Ukrainian Academician Vernadsky station on the Antarctic Peninsula (W 64 o 16 ' , S 65 o 15 ' ), where radon is measured by two types of etched track Rn dosimeter and 4 types of continuous radon monitoring devices is presented. Some selected results of research work are described related to: (i) analysis of radon storms, defined as an abrupt increase of 222 Rn during the occurrence of a cyclone, and its applicability for the study of the transport of air masses of continental origin to Antarctica; (ii) a study of the correlation of changes of radon concentration and geomagnetic field induced by tectonic activity and its application to predicting tectonomagnetic anomalies, and (iii) verification of a newly developed theoretical model based on noise analysis of the measured radon signal for earthquake prediction. Suggestions for future utilization of radon for basic research in Antarctica (and not only in Antarctica) conclude the contribution. conclude the contribution

Anthropogenic impacts on marine ecosystems in Antarctica.

Science.gov (United States)

Aronson, Richard B; Thatje, Sven; McClintock, James B; Hughes, Kevin A

2011-03-01

Antarctica is the most isolated continent on Earth, but it has not escaped the negative impacts of human activity. The unique marine ecosystems of Antarctica and their endemic faunas are affected on local and regional scales by overharvesting, pollution, and the introduction of alien species. Global climate change is also having deleterious impacts: rising sea temperatures and ocean acidification already threaten benthic and pelagic food webs. The Antarctic Treaty System can address local- to regional-scale impacts, but it does not have purview over the global problems that impinge on Antarctica, such as emissions of greenhouse gases. Failure to address human impacts simultaneously at all scales will lead to the degradation of Antarctic marine ecosystems and the homogenization of their composition, structure, and processes with marine ecosystems elsewhere. © 2011 New York Academy of Sciences.

45 CFR 674.4 - Restrictions on collection of meteorites in Antarctica.

Science.gov (United States)

2010-10-01

... Antarctica. 674.4 Section 674.4 Public Welfare Regulations Relating to Public Welfare (Continued) NATIONAL SCIENCE FOUNDATION ANTARCTIC METEORITES § 674.4 Restrictions on collection of meteorites in Antarctica. No person may collect meteorites in Antarctica for other than scientific research purposes. ...

Geoethical approach to mineral activities in Antarctica

Science.gov (United States)

Talalay, Pavel

2013-04-01

Antarctica is the outermost from civilization space continent. From 14.0 million km2 of surface area about 98% of Antarctica is covered by ice that averages at least 1.6 km in thickness. Geologically, the continent is the least explored in the world, and it is almost absolutely unknown what mineral resources Antarctica has as they are buried in rock that is covered by a thick ice sheet. It is thought to have large and valuable mineral deposits under the ice. This is because of what has been found in samples taken from the small areas of rock that are exposed, and also from what has been found in South Africa and South America. Up until 180 million years ago, Antarctica was a part of the Gondwanaland super continent, attached to South America, the Southern part of Africa, India and Australia, these continents then drifted apart until they reached their current positions. This leads to a possibility that Antarctica may also share some of the mineral wealth of these continents. Right now on the ice-free areas of Antarctica iron ore, chromium, copper, gold, nickel, platinum, coal and hydrocarbons have been found. The Protocol on Environmental Protection to the Antarctic Treaty, also known as the Madrid Protocol, was signed in 1991 by the signatories to the Antarctic Treaty and became law in January 1998. The Protocol provides for comprehensive protection of the Antarctic environment and associated ecosystems and includes a ban on all commercial mining for at least fifty years (this is up for review in 2041). Current climate change and melting ice in Polar Regions is opening up new opportunities to exploit mineral and oil resources. Even Antarctica's weather, ice and distance from any industrialized areas mean that mineral extraction would be extremely expensive and also extremely dangerous, the depletion of mineral recourses on the Earth can reverse banning of mining in Antarctica in future. There is no question that any resource exploitation in Antarctica will cause

Mineral resources potential of Antarctica

National Research Council Canada - National Science Library

Splettstoesser, John F; Dreschhoff, Gisela A. M

1990-01-01

.... This volume of the Antarctic Research Series results from an attempt to assemble a summary of current factual knowledge and scientific data related to issues of mineral resources in Antarctica...

Crustal heat production and estimate of terrestrial heat flow in central East Antarctica, with implications for thermal input to the East Antarctic ice sheet

Science.gov (United States)

Goodge, John W.

2018-02-01

Terrestrial heat flow is a critical first-order factor governing the thermal condition and, therefore, mechanical stability of Antarctic ice sheets, yet heat flow across Antarctica is poorly known. Previous estimates of terrestrial heat flow in East Antarctica come from inversion of seismic and magnetic geophysical data, by modeling temperature profiles in ice boreholes, and by calculation from heat production values reported for exposed bedrock. Although accurate estimates of surface heat flow are important as an input parameter for ice-sheet growth and stability models, there are no direct measurements of terrestrial heat flow in East Antarctica coupled to either subglacial sediment or bedrock. As has been done with bedrock exposed along coastal margins and in rare inland outcrops, valuable estimates of heat flow in central East Antarctica can be extrapolated from heat production determined by the geochemical composition of glacial rock clasts eroded from the continental interior. In this study, U, Th, and K concentrations in a suite of Proterozoic (1.2-2.0 Ga) granitoids sourced within the Byrd and Nimrod glacial drainages of central East Antarctica indicate average upper crustal heat production (Ho) of about 2.6 ± 1.9 µW m-3. Assuming typical mantle and lower crustal heat flux for stable continental shields, and a length scale for the distribution of heat production in the upper crust, the heat production values determined for individual samples yield estimates of surface heat flow (qo) ranging from 33 to 84 mW m-2 and an average of 48.0 ± 13.6 mW m-2. Estimates of heat production obtained for this suite of glacially sourced granitoids therefore indicate that the interior of the East Antarctic ice sheet is underlain in part by Proterozoic continental lithosphere with an average surface heat flow, providing constraints on both geodynamic history and ice-sheet stability. The ages and geothermal characteristics of the granites indicate that crust in central

Increased West Antarctic and unchanged East Antarctic ice discharge over the last 7 years

Science.gov (United States)

Gardner, Alex S.; Moholdt, Geir; Scambos, Ted; Fahnstock, Mark; Ligtenberg, Stefan; van den Broeke, Michiel; Nilsson, Johan

2018-02-01

Ice discharge from large ice sheets plays a direct role in determining rates of sea-level rise. We map present-day Antarctic-wide surface velocities using Landsat 7 and 8 imagery spanning 2013-2015 and compare to earlier estimates derived from synthetic aperture radar, revealing heterogeneous changes in ice flow since ˜ 2008. The new mapping provides complete coastal and inland coverage of ice velocity north of 82.4° S with a mean error of image pairs acquired during the daylight period. Using an optimized flux gate, ice discharge from Antarctica is 1929 ± 40 Gigatons per year (Gt yr-1) in 2015, an increase of 36 ± 15 Gt yr-1 from the time of the radar mapping. Flow accelerations across the grounding lines of West Antarctica's Amundsen Sea Embayment, Getz Ice Shelf and Marguerite Bay on the western Antarctic Peninsula, account for 88 % of this increase. In contrast, glaciers draining the East Antarctic Ice Sheet have been remarkably constant over the period of observation. Including modeled rates of snow accumulation and basal melt, the Antarctic ice sheet lost ice at an average rate of 183 ± 94 Gt yr-1 between 2008 and 2015. The modest increase in ice discharge over the past 7 years is contrasted by high rates of ice sheet mass loss and distinct spatial patters of elevation lowering. The West Antarctic Ice Sheet is experiencing high rates of mass loss and displays distinct patterns of elevation lowering that point to a dynamic imbalance. We find modest increase in ice discharge over the past 7 years, which suggests that the recent pattern of mass loss in Antarctica is part of a longer-term phase of enhanced glacier flow initiated in the decades leading up to the first continent-wide radar mapping of ice flow.

Isolation of Campylobacter spp. from Three Species of Antarctic Penguins in Different Geographic Locations.

Science.gov (United States)

García-Peña, F J; Llorente, M T; Serrano, T; Ruano, M J; Belliure, J; Benzal, J; Herrera-León, S; Vidal, V; D'Amico, V; Pérez-Boto, D; Barbosa, A

2017-03-01

The presence of Campylobacter species was studied in three Antarctic penguin species, Adélie (Pygoscelis adeliae), chinstrap (Pygoscelis antarctica) and gentoo (Pygoscelis papua). A total of 390 penguins were captured in 12 different rookeries along the Antarctic Peninsula with differences in the amount of human visitation: six colonies were highly visited [Stranger Point, King George Island (P. papua and P. adeliae); Hannah Point, Livingston Island (P. papua and P. antarctica); Deception Island (P. antarctica); and Paradise Bay, Antarctic Peninsula (P. papua)], and six colonies were rarely visited [Devil's Point, Byers Peninsula, Livingston Island (P. papua); Cierva Cove, Antarctic Peninsula (P. papua); Rongé Island (P. papua and P. antarctica); Yalour Island (P. adeliae); and Avian Island (P. adeliae)]. A total of 23 strains were isolated from penguins from nine different rookeries. Campylobacter lari subsp. lari was isolated from eight samples (seven from P. papua and one from P. adeliae); C. lari subsp. concheus from 13 (ten from P. adeliae and three from P. antarctica) and C. volucris from two samples (both from P. papua). We did not find any significant differences in the prevalence of Campylobacter spp. between the populations in highly and rarely visited areas. This is the first report of C. lari subsp. concheus and C. volucris isolation from penguins in the Antarctic region.

Antarctic aerosols - A review

Science.gov (United States)

Shaw, Glenn E.

1988-02-01

Tropospheric aerosols with the diameter range of half a micron reside in the atmosphere for tens of days and teleconnect Antarctica with other regions by transport that reaches planetary scales of distances; thus, the aerosol on the Antarctic ice represents 'memory modules' of events that took place at regions separated from Antarctica by tens of thousands of kilometers. In terms of aerosol mass, the aerosol species include insoluble crustal products (less than 5 percent), transported sea-salt residues (highly variable but averaging about 10 percent), Ni-rich meteoric material, and anomalously enriched material with an unknown origin. Most (70-90 percent by mass) of the aerosol over the Antarctic ice shield, however, is the 'natural acid sulfate aerosol', apparently deriving from biological processes taking place in the surrounding oceans.

Snow noise disturbance in Antarctic radio communications and development of mobile antenna for snow vehicle in Antarctica

Directory of Open Access Journals (Sweden)

Isao Fukushima

1997-07-01

Full Text Available Radio operators of the Japanese Antarctic Research Expedition (JARE have encountered critical radio noise disturbances caused by blizzards during oversnow travel. This noise appears to be caused by corona discharge at the edges of the vertical whip antenna. This paper describes several examples of snow noise experienced in Antarctica by JARE, the mechanism of generation of the noise, and a method of reducing the intensity of the noise. It also describes a High Effeciency Transmission Line Antenna which is small enough to mount on a snow vehicle and reduces the intensity of the snow noise.

Emerging spatial patterns in Antarctic prokaryotes.

Science.gov (United States)

Chong, Chun-Wie; Pearce, David A; Convey, Peter

2015-01-01

Recent advances in knowledge of patterns of biogeography in terrestrial eukaryotic organisms have led to a fundamental paradigm shift in understanding of the controls and history of life on land in Antarctica, and its interactions over the long term with the glaciological and geological processes that have shaped the continent. However, while it has long been recognized that the terrestrial ecosystems of Antarctica are dominated by microbes and their processes, knowledge of microbial diversity and distributions has lagged far behind that of the macroscopic eukaryote organisms. Increasing human contact with and activity in the continent is leading to risks of biological contamination and change in a region whose isolation has protected it for millions of years at least; these risks may be particularly acute for microbial communities which have, as yet, received scant recognition and attention. Even a matter apparently as straightforward as Protected Area designation in Antarctica requires robust biodiversity data which, in most parts of the continent, remain almost completely unavailable. A range of important contributing factors mean that it is now timely to reconsider the state of knowledge of Antarctic terrestrial prokaryotes. Rapid advances in molecular biological approaches are increasingly demonstrating that bacterial diversity in Antarctica may be far greater than previously thought, and that there is overlap in the environmental controls affecting both Antarctic prokaryotic and eukaryotic communities. Bacterial dispersal mechanisms and colonization patterns remain largely unaddressed, although evidence for regional evolutionary differentiation is rapidly accruing and, with this, there is increasing appreciation of patterns in regional bacterial biogeography in this large part of the globe. In this review, we set out to describe the state of knowledge of Antarctic prokaryote diversity patterns, drawing analogy with those of eukaryote groups where appropriate

Airspace: Antarctic Sound Transmission

OpenAIRE

Polli, Andrea

2009-01-01

This paper investigates how sound transmission can contribute to the public understanding of climate change within the context of the Poles. How have such transmission-based projects developed specifically in the Arctic and Antarctic, and how do these works create alternative pathways in order to help audiences better understand climate change? The author has created the media project Sonic Antarctica from a personal experience of the Antarctic. The work combines soundscape recordings and son...

Petroleum and mineral resources of Antarctica

Science.gov (United States)

Kovar, Karel; Behrendt, John Charles

1983-01-01

No known petroleum or mineral resources occur in Antarctica. The data on these subjects have been collected, mainly since the IGY (International Geophysical Year), 1957-58, as a part of other research carried out by geologists and geophysicists from a number of countries. Specific resource-related studies have not been made. Wright and Williams (1974) summarized what was known of Antarctic mineral resources a decade ago.The U.S. Geological Survey has been actively pursuing various investigations in Antarctica since 194 7. In the course of this work and that of our colleagues elsewhere in the United States and in other countries, much information relevant to petroleum and mineral resources has been obtained. Since 1976, modern state-of-the-art multichannel seismic reflection and aeromagnetic surveys by several countries over the continental margin of Antarctica have indicated thick sedimentary basins. However, no offshore drilling beneath the continental shelf has taken place since the DSDP (Deep Sea Drilling Project) holes in the Ross Sea in 1973. Geologic field investigations begun at the turn of the twentieth century have been intensified in the past two decades; most rock outcrops have been visited and samples collected. Technology to exploit resources, particularly in the Arctic, has been developing at a rapid rate, and much of it could be applied to Antarctica. As a result of the petroleum price increases of the past decade, the attention of a number of countries has turned to Antarctica, but under the policy of "voluntary restraint" adopted by the Antarctic Treaty nations, no active petroleum or mineral exploration is taking place. The Antarctic treaty countries are in the process of negotiating an Antarctic mineral resources regime that is anticipated to be completed within the next several years. Therefore it seemed timely to us to readdress the question of petroleum and mineral resources. These reports review and summarize the available information. The

Managing Human Activities in Antarctica : Should Wilderness Protection Count?

NARCIS (Netherlands)

Bastmeijer, C.J.

2005-01-01

Antarctica is often described as one of the world's last wildernesses. In harmony with this general perception, the wilderness values of Antarctica received legal status with the adoption of the Protocol on Environmental Protection to the Antarctic Treaty. Article 3(1) of the Protocol obliges each

Kordia antarctica sp. nov., isolated from Antarctic seawater.

Science.gov (United States)

Baek, Kiwoon; Choi, Ahyoung; Kang, Ilnam; Lee, Kiyoung; Cho, Jang-Cheon

2013-10-01

A Gram-staining-negative, chemoheterotrophic, yellow-pigmented, non-motile, flexirubin-negative, facultatively anaerobic bacterium, designated strain IMCC3317(T), was isolated from a coastal seawater sample from the Antarctic Penninsula. Optimal growth of strain IMCC3317(T) was observed at 20 °C, pH 8.0 and in the presence of 2-3 % NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain IMCC3317(T) belonged to the genus Kordia and was closely related to Kordia algicida OT-1(T) (96.7 % sequence similarity) and Kordia periserrulae IMCC1412(T) (96.1 % sequence similarity). The major fatty acids were 10-methyl C16 : 0 and/or iso-C16 : 1ω9c, iso-C17 : 0 3-OH, iso-C15 : 0 and anteiso-C15 : 0. The G+C content of the genomic DNA was 35.1 mol%. The strain contained menaquinone-6 (MK-6) as the respiratory quinone. The polar lipids detected in the strain were phosphatidylethanolamine and unknown aminophospholipids, aminolipids and polar lipids. On the basis of phylogenetic distinction and differential phenotypic characteristics, it is suggested that strain IMCC3317(T) ( = KCTC 32292(T) = NBRC 109401(T)) be assigned to the genus Kordia as the type strain of a novel species, for which the name Kordia antarctica sp. nov. is proposed.

Antarctic climate variability on regional and continental scales over the last 2000 years

Directory of Open Access Journals (Sweden)

B. Stenni

2017-11-01

Full Text Available Climate trends in the Antarctic region remain poorly characterized, owing to the brevity and scarcity of direct climate observations and the large magnitude of interannual to decadal-scale climate variability. Here, within the framework of the PAGES Antarctica2k working group, we build an enlarged database of ice core water stable isotope records from Antarctica, consisting of 112 records. We produce both unweighted and weighted isotopic (δ18O composites and temperature reconstructions since 0 CE, binned at 5- and 10-year resolution, for seven climatically distinct regions covering the Antarctic continent. Following earlier work of the Antarctica2k working group, we also produce composites and reconstructions for the broader regions of East Antarctica, West Antarctica and the whole continent. We use three methods for our temperature reconstructions: (i a temperature scaling based on the δ18O–temperature relationship output from an ECHAM5-wiso model simulation nudged to ERA-Interim atmospheric reanalyses from 1979 to 2013, and adjusted for the West Antarctic Ice Sheet region to borehole temperature data, (ii a temperature scaling of the isotopic normalized anomalies to the variance of the regional reanalysis temperature and (iii a composite-plus-scaling approach used in a previous continent-scale reconstruction of Antarctic temperature since 1 CE but applied to the new Antarctic ice core database. Our new reconstructions confirm a significant cooling trend from 0 to 1900 CE across all Antarctic regions where records extend back into the 1st millennium, with the exception of the Wilkes Land coast and Weddell Sea coast regions. Within this long-term cooling trend from 0 to 1900 CE, we find that the warmest period occurs between 300 and 1000 CE, and the coldest interval occurs from 1200 to 1900 CE. Since 1900 CE, significant warming trends are identified for the West Antarctic Ice Sheet, the Dronning Maud Land coast and the

Decadal Trends in Abundance, Size and Condition of Antarctic Toothfish in McMurdo Sound, Antarctica, 1972-2010

Science.gov (United States)

Ainley, David G.; Nur, Nadav; Eastman, Joseph T.; Ballard. Grant; Parkinson, Claire L; Evans, Clive W.; DeVries, Arthur L.

2012-01-01

We report analyses of a dataset spanning 38 years of near-annual fishing for Antarctic toothfish Dissostichus mawsoni, using a vertical setline through the fast ice of McMurdo Sound, Antarctica, 1972-2010. This constitutes one of the longest biological time series in the Southern Ocean, and certainly the longest for any fish. Fish total length, condition and catch per unit effort (CPUE) were derived from the more than 5500 fish caught. Contrary to expectation, length-frequency was dominated by fish in the upper half of the industrial catch. The discrepancy may be due to biases in the sampling capabilities of vertical (this study) versus benthic (horizontal) fishing gear (industry long lines), related to the fact that only large Antarctic toothfish (more than 100 cm TL) are neutrally buoyant and occur in the water column. Fish length and condition increased from the early 1970s to the early 1990s and then decreased, related to sea ice cover, with lags of 8 months to 5 years, and may ultimately be related to the fishery (which targets large fish) and changes in the Southern Annular Mode through effects on toothfish main prey, Antarctic silverfish Pleuragramma antarcticum. CPUE was constant through 2001 and then decreased dramatically, likely related to the industrial fishery, which began in 1996 and which concentrates effort over the Ross Sea slope, where tagged McMurdo fish have been found. Due to limited prey choices and, therefore, close coupling among mesopredators of the Ross Sea, Antarctic toothfish included, the fishery may be altering the trophic structure of the Ross Sea.

Marisediminicola antarctica gen. nov., sp. nov., an actinobacterium isolated from the Antarctic.

Science.gov (United States)

Li, Hui-Rong; Yu, Yong; Luo, Wei; Zeng, Yin-Xin

2010-11-01

Strain ZS314(T) was isolated from a sandy intertidal sediment sample collected from the coastal area off the Chinese Antarctic Zhongshan Station, east Antarctica (6 9° 22' 13″ S 76 ° 21' 41″ E). The cells were Gram-positive, motile, short rods. The temperature range for growth was 0-26 °C and the pH for growth ranged from 5 to 10, with optimum growth occurring within the temperature range 18-23 °C and pH range 6.0-8.0. Growth occurred in the presence of 0-6 % (w/v) NaCl, with optimum growth occurring in the presence of 2-4 % (w/v) NaCl. Strain ZS314(T) had MK-10 as the major menaquinone and anteiso-C(15 : 0), iso-C(16 : 0) and anteiso-C(17 : 0) as major fatty acids. The cell-wall peptidoglycan type was B2β with ornithine as the diagnostic diamino acid. The major polar lipids were diphosphatidylglycerol and phosphatidylglycerol. The genomic DNA G+C content was approximately 67 mol%. Phylogenetic analysis based on 16S rRNA gene sequence similarity showed that strain ZS314(T) represents a new lineage in the family Microbacteriaceae. On the basis of the phylogenetic analyses and phenotypic characteristics, a new genus, namely Marisediminicola gen. nov., is proposed, harbouring the novel species Marisediminicola antarctica sp. nov. with the type strain ZS314(T) (=DSM 22350(T) =CCTCC AB 209077(T)).

A view of the upper atmosphere from Antarctica

International Nuclear Information System (INIS)

Rycroft, M.

1985-01-01

The paper reviews the phenomena associated with the earth's upper atmosphere, as detected from field stations on the Antarctic continent. A description is given of the earth's atmosphere, including the auroral regions, the ionosphere and magnetosphere. Geospace phenomena investigated from the Antarctic are described, and include whistlers, chorus and trimpi events. The earth's geomagnetic field is measured at several Antarctic stations. Possibilities for future projects in Antarctica are also discussed. (U.K.)

Influence of Persistent Wind Scour on the Surface Mass Balance of Antarctica

Science.gov (United States)

Das, Indrani; Bell, Robin E.; Scambos, Ted A.; Wolovick, Michael; Creyts, Timothy T.; Studinger, Michael; Fearson, Nicholas; Nicolas, Julien P.; Lenaerts, Jan T. M.; vandenBroeke, Michiel R.

2013-01-01

Accurate quantification of surface snow accumulation over Antarctica is a key constraint for estimates of the Antarctic mass balance, as well as climatic interpretations of ice-core records. Over Antarctica, near-surface winds accelerate down relatively steep surface slopes, eroding and sublimating the snow. This wind scour results in numerous localized regions (Antarctica. The scour zones are persistent because they are controlled by bedrock topography. On the basis of our Dome A observations, we develop an empirical model to predict wind-scour zones across the Antarctic continent and find that these zones are predominantly located in East Antarctica. We estimate that approx. 2.7-6.6% of the surface area of Antarctica has persistent negative net accumulation due to wind scour, which suggests that, across the continent, the snow mass input is overestimated by 11-36.5 Gt /yr in present surface-mass-balance calculations.

Topographic Steering of Enhanced Ice Flow at the Bottleneck Between East and West Antarctica

DEFF Research Database (Denmark)

Winter, Kate; Ross, Neil; Ferraccioli, Fausto

2018-01-01

Hypothesized drawdown of the East Antarctic Ice Sheet through the “bottleneck” zone between East and West Antarctica would have significant impacts for a large proportion of the Antarctic Ice Sheet. Earth observation satellite orbits and a sparseness of radio echo sounding data have restricted...... investigations of basal boundary controls on ice flow in this region until now. New airborne radio echo sounding surveys reveal complex topography of high relief beneath the southernmost Weddell/Ross ice divide, with three subglacial troughs connecting interior Antarctica to the Foundation and Patuxent Ice...... Streams and Siple Coast ice streams. These troughs route enhanced ice flow through the interior of Antarctica but limit potential drawdown of the East Antarctic Ice Sheet through the bottleneck zone. In a thinning or retreating scenario, these topographically controlled corridors of enhanced flow could...

Evaluation of uranium resources in Antarctica

International Nuclear Information System (INIS)

Zeller, E.J.; Dreschhoff, G.A.M.

1980-01-01

The continent of Antarctica comprises roughly nine per cent of the total land surface of the earth and is the only large land area that has been left almost totally unexplored for uranium resources. In 1976 the first systematic uranium resource evaluation, entitled Antarctica International Radiometric Survey, was started as a part of the US Antarctic Research Program. This project was staffed jointly by scientists from the University of Kansas and the Bundesanstalt fuer Geowissenschaften und Rohstoffe of the Federal Republic of Germany. The survey has continued for three antarctic field seasons and an extension of operations for the next four years has been approved. Two areas in the Transantarctic Mountains and one part of Marie Byrd Land have been surveyed by airborne gamma-ray spectrometric methods. The work that has been conducted demonstrates clearly that radiometric surveys can be performed successfully under the rigorous climatic conditions in Antarctica, and that significant and reproducible data can be obtained. So far no substantial concentrations of uranium have been detected but deposits of thorium minerals have been found. (author)

Direct evidence of histopathological impacts of wastewater discharge on resident Antarctic fish (Trematomus bernacchii) at Davis Station, East Antarctica.

Science.gov (United States)

Corbett, Patricia A; King, Catherine K; Stark, Jonathan S; Mondon, Julie A

2014-10-15

During the 2009/2010 summer, a comprehensive environmental impact assessment (EIA) of the wastewater discharge at Davis Station, East Antarctica was completed. As part of this, histological alteration of gill and liver tissue in Antarctic Rock-cod (Trematomus bernacchii) from four sites along a spatial gradient from the wastewater outfall were assessed. All fish within 800 m of the outfall exhibited significant histological changes in both tissues. Common pathologies observed in fish closest to the outfall include proliferation of epithelial cells with associated secondary lamellar fusion in the gills and multifocal granulomata with inflammation and necrosis as well as cysts in the liver. Fish from sites >800 m from the outfall also exhibited alterations but to a lesser degree, with prevalence and severity decreasing with increasing distance from the outfall. This study highlights the value of histopathological investigations as part of EIAs and provides the first evidence of sub-lethal alteration associated with wastewater discharge in East Antarctica. Copyright © 2014 Elsevier Ltd. All rights reserved.

Antioxidant Responses Induced by UVB Radiation in Deschampsia antarctica Desv.

Directory of Open Access Journals (Sweden)

Hans Köhler

2017-05-01

Full Text Available Deschampsia antarctica Desv. is one of two vascular plants that live in the Maritime Antarctic Territory and is exposed to high levels of ultraviolet-B (UVB radiation. In this work, antioxidant physiology of D. antarctica was studied in response to UVB induced oxidative changes. Samples were collected from Antarctica and maintained in vitro culture during 2 years. Plants were sub-cultured in a hydroponic system and exposed to 21.4 kJ m-2 day-1, emulating summer Antarctic conditions. Results showed rapid and significant increases in reactive oxygen species (ROS at 3 h, which rapidly decreased. No dramatic changes were observed in photosynthetic efficiency, chlorophyll content, and level of thiobarbituric acid reactive species (MDA. The enzymatic (superoxide dismutase, SOD and total peroxidases, POD and non-enzymatic antioxidant activity (total phenolic increased significantly in response to UVB treatment. These findings suggest that tolerance of D. antarctica to UVB radiation could be attributed to its ability to activate both enzymatic and non-enzymatic antioxidant systems.

Increased West Antarctic and unchanged East Antarctic ice discharge over the last 7 years

Directory of Open Access Journals (Sweden)

A. S. Gardner

2018-02-01

Full Text Available Ice discharge from large ice sheets plays a direct role in determining rates of sea-level rise. We map present-day Antarctic-wide surface velocities using Landsat 7 and 8 imagery spanning 2013–2015 and compare to earlier estimates derived from synthetic aperture radar, revealing heterogeneous changes in ice flow since ∼ 2008. The new mapping provides complete coastal and inland coverage of ice velocity north of 82.4° S with a mean error of < 10 m yr−1, resulting from multiple overlapping image pairs acquired during the daylight period. Using an optimized flux gate, ice discharge from Antarctica is 1929 ± 40 Gigatons per year (Gt yr−1 in 2015, an increase of 36 ± 15 Gt yr−1 from the time of the radar mapping. Flow accelerations across the grounding lines of West Antarctica's Amundsen Sea Embayment, Getz Ice Shelf and Marguerite Bay on the western Antarctic Peninsula, account for 88 % of this increase. In contrast, glaciers draining the East Antarctic Ice Sheet have been remarkably constant over the period of observation. Including modeled rates of snow accumulation and basal melt, the Antarctic ice sheet lost ice at an average rate of 183 ± 94 Gt yr−1 between 2008 and 2015. The modest increase in ice discharge over the past 7 years is contrasted by high rates of ice sheet mass loss and distinct spatial patters of elevation lowering. The West Antarctic Ice Sheet is experiencing high rates of mass loss and displays distinct patterns of elevation lowering that point to a dynamic imbalance. We find modest increase in ice discharge over the past 7 years, which suggests that the recent pattern of mass loss in Antarctica is part of a longer-term phase of enhanced glacier flow initiated in the decades leading up to the first continent-wide radar mapping of ice flow.

The oldest plesiosaur (Reptilia, Sauropterygia from Antarctica

Directory of Open Access Journals (Sweden)

Alexander Wilhelm Armin Kellner

2011-06-01

Full Text Available Antarctic plesiosaurs are known from the Upper Cretaceous López de Bertodano and Snow Hill Island formations (Campanian to upper Maastrichtian, which crop out within the James Ross Basin region of the Antarctic Peninsula. Here we describe the first plesiosaur fossils from the Lachman Crags Member of the Santa Marta Formation, north-western James Ross Island. This material constitutes the stratigraphically oldest plesiosaur occurrence presently known from Antarctica, extending the occurrence of plesiosaurians in this continent back to Santonian times (86.3–83.5 Mya. Furthermore, MN 7163-V represents the first plesiosaur from this region not referable to the Elasmosauridae nor Aristonectes, indicating a greater diversity of this group of aquatic reptiles in Antarctica than previously suspected.

Biological invasions in the Antarctic: extent, impacts and implications.

Science.gov (United States)

Frenot, Yves; Chown, Steven L; Whinam, Jennie; Selkirk, Patricia M; Convey, Peter; Skotnicki, Mary; Bergstrom, Dana M

2005-02-01

Alien microbes, fungi, plants and animals occur on most of the sub-Antarctic islands and some parts of the Antarctic continent. These have arrived over approximately the last two centuries, coincident with human activity in the region. Introduction routes have varied, but are largely associated with movement of people and cargo in connection with industrial, national scientific program and tourist operations. The large majority of aliens are European in origin. They have both direct and indirect impacts on the functioning of species-poor Antarctic ecosystems, in particular including substantial loss of local biodiversity and changes to ecosystem processes. With rapid climate change occurring in some parts of Antarctica, elevated numbers of introductions and enhanced success of colonization by aliens are likely, with consequent increases in impacts on ecosystems. Mitigation measures that will substantially reduce the risk of introductions to Antarctica and the sub-Antarctic must focus on reducing propagule loads on humans, and their food, cargo, and transport vessels.

Ross Ice Shelf, Antarctic Ice and Clouds

Science.gov (United States)

1991-01-01

In this view of Antarctic ice and clouds, (56.5S, 152.0W), the Ross Ice Shelf of Antarctica is almost totally clear, showing stress cracks in the ice surface caused by wind and tidal drift. Clouds on the eastern edge of the picture are associated with an Antarctic cyclone. Winds stirred up these storms have been known to reach hurricane force.

Twenty-five years of Antarctic upper atmosphere research at Rhodes University

International Nuclear Information System (INIS)

Gledhill, J.A.

1987-01-01

South Africa, as one of the twelve signatories of the Antarctic Treaty is required to establish presence in Antarctica. In this article the past 25 years of upper atmosphere research in Antarctica, and the ionosphere programme at SANAE (South African National Antarctic Expedition) are described. The use of ionograms, Barry ionosondes, airglow photometers, oblique incidence ionograms and the digitized FM ionosonde are discussed as well as anomalous daily variations, the ionospheric effects of particle precipitation, Atmosphere Explorer-C and project ISAAC (International South Atlantic Anomaly Campaign)

Environmental contamination in Antarctic ecosystems.

Science.gov (United States)

Bargagli, R

2008-08-01

Although the remote continent of Antarctica is perceived as the symbol of the last great wilderness, the human presence in the Southern Ocean and the continent began in the early 1900s for hunting, fishing and exploration, and many invasive plant and animal species have been deliberately introduced in several sub-Antarctic islands. Over the last 50 years, the development of research and tourism have locally affected terrestrial and marine coastal ecosystems through fuel combustion (for transportation and energy production), accidental oil spills, waste incineration and sewage. Although natural "barriers" such as oceanic and atmospheric circulation protect Antarctica from lower latitude water and air masses, available data on concentrations of metals, pesticides and other persistent pollutants in air, snow, mosses, lichens and marine organisms show that most persistent contaminants in the Antarctic environment are transported from other continents in the Southern Hemisphere. At present, levels of most contaminants in Antarctic organisms are lower than those in related species from other remote regions, except for the natural accumulation of Cd and Hg in several marine organisms and especially in albatrosses and petrels. The concentrations of organic pollutants in the eggs of an opportunistic top predator such as the south polar skua are close to those that may cause adverse health effects. Population growth and industrial development in several countries of the Southern Hemisphere are changing the global pattern of persistent anthropogenic contaminants and new classes of chemicals have already been detected in the Antarctic environment. Although the Protocol on Environmental Protection to the Antarctic Treaty provides strict guidelines for the protection of the Antarctic environment and establishes obligations for all human activity in the continent and the Southern Ocean, global warming, population growth and industrial development in countries of the Southern

Chilean Antarctic Stations on King George Island

OpenAIRE

Katsutada Kaminuma

2000-01-01

The purpose of my visit to Chilean Antarctic Stations was to assess the present status of geophysical observations and research, as the South Shetland Island, West Antarctica, where the stations are located, are one of the most active tectonic regions on the Antarctic plate. The Instituto Antartico Chileno (INACH) kindly gave me a chance to stay in Frei/Escudero Bases as an exchange scientist under the Antarctic Treaty for two weeks in January 2000. I stayed in Frei Base as a member of a geol...

Dynamics of the ice mass in Antarctica in the time of warming

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V. M. Kotlyakov

2017-01-01

Full Text Available The modern age of global warming affect the general state of the Antarctic ice sheet and its mass balance. Studies of the Southern polar region of the Earth during the International Geophysical Year  (1957–1958 called the assumption of growth in the modern ice mass in East Antarctica. However, with the development of new methods, this conclusion has been questioned. At the turn of the century the study of global processes Earth started to use the satellite radar or laser altimetry and satellite gravimetry, which allows determining change of different masses on the Earth, including ice bodies. From the beginning of the XXI century, these methods have been used to calculate the continental ice balance. In our study, we analyze different data of recent years, supporting the earlier conclusion on continued growth of the ice mass in East Antarctica. How‑ ever, in West Antarctica and the Antarctic Peninsula, on the contrary, there is increased loss of ice, leveling the increased income of ice mass of in the Central Antarctica. So all in all in the modern era of global warm‑ ing, the ice mass in Antarctica appears to be decreasing despite some growth of the East Antarctic ice sheet. Fluctuations of land ice mass reflect in the sea level variations, but in comparison with the scale of the Ant‑ arctic ice sheet its contribution to sea‑level rise is not so significant. The main reason for this is that the mass accumulation in East Antarctica with significant probability prevails over the ice outflow.

The transition from diffuse to focused extension: Modeled evolution of the West Antarctic Rift system

Science.gov (United States)

Huerta, Audrey D.; Harry, Dennis L.

2007-03-01

Two distinct stages of extension are recognized in the West Antarctic Rift system (WARS). During the first stage, beginning in the Late Cretaceous, extension was broadly distributed throughout much of West Antarctica. A second stage of extension in the late Paleogene was focused primarily in the Victoria Land Basin, near the boundary with the East Antarctic craton. The transition to focused extension was roughly coeval with volcanic activity and strike-slip faulting in the adjacent Transantarctic Mountains. This spatial and temporal correspondence suggests that the transition in extensional style could be the result of a change in plate motions or impingement of a plume. Here we use finite element models to study the processes and conditions responsible for the two-stage evolution of rifting in the WARS. Model results indicate that the transition from a prolonged period of broadly distributed extension to a later period of focused rifting did not require a change in the regional stress regime (changes in plate motion), or deep mantle thermal state (impingement of a plume). Instead, we attribute the transition from diffuse to focused extension to an early stage dominated by the initially weak accreted lithosphere of West Antarctica, and a later stage that concentrated around a secondary weakness located at the boundary between the juvenile West Antarctica lithosphere and Precambrian East Antarctic craton. The modeled transition in extension from the initially weak West Antarctica region to the secondary weakness at the West Antarctic-East Antarctic boundary is precipitated by strengthening of the West Antarctica lithosphere during syn-extensional thinning and cooling. The modeled syn-extensional strengthening of the WARS lithosphere promotes a wide-rift mode of extension between 105 and ˜ 65 Ma. By ˜ 65 Ma most of the extending WARS region becomes stronger than the area immediately adjacent to the East Antarctic craton and extension becomes concentrated near the

Coastal-change and glaciological map of the Bakutis Coast, Antarctica

Science.gov (United States)

Swithinbank, Charles; Williams, Richard S.; Ferrigno, Jane G.; Seekins, B.A.; Lucchita, B.K.; Rosanova, Christine E.

1997-01-01

Changes in the area and volume of the polar ice sheets are intricately linked to changes in global climate, and the resulting changes in sea level may severely impact the densely populated coastal regions on Earth. Loss of the West Antarctic part of the Antarctic ice sheet alone could cause a sea-level rise of approximately 6 m. The potential sea-level rise after melting of the entire Antarctic ice sheet is estimated to be 65 m to 73 m. In spite of its importance, the mass balance (the net volumetric gain or loss) of the Antarctic ice sheet is poorly known; it is not known whether the ice sheet is growing or shrinking. As a result, measurement of changes in the Antarctic ice sheet was given a very high priority in recommendations by the Polar Research Board of the National Research Council (1986), by the Scientific Committee on Antarctic Research (SCAR) (1989), and by the National Science Foundation's (1990) Division of Polar Programs. An archive of early 1970's Landsat 1, 2, and 3 Multispectral Scanner (MSS) images of Antarctica and the fact that the repeat coverage with satellite images provided an excellent means of documenting changes in the coastline of Antarctica provided the impetus for carrying out a comprehensive analysis of the glaciological features of the coastal regions and changes in ice fronts of Antarctica. The project was later modified to include Landsat 4 and 5 MSS and Thematic Mapper (TM) and RADARSAT images to compare changes over a 20- to 25- year time interval and to prepare a series of 24 1:1,000,000-scale and 1 1:5,000,000-scale U.S. Geological Survey Geologic Investigations Series Maps ('I-Maps') (Williams and others, 1995; Williams and Ferrigno, 1998; and Ferrigno and others, 2002) in both paper and digital format.

The intraseasonal variability of winter semester surface air temperature in Antarctica

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Lejiang Yu

2011-02-01

Full Text Available This study investigates systematically the intraseasonal variability of surface air temperature over Antarctica by applying empirical orthogonal function (EOF analysis to the National Centers for Environmental Prediction, US Department of Energy, Reanalysis 2 data set for the period of 1979 through 2007. The results reveal the existence of two major intraseasonal oscillations of surface temperature with periods of 26–30 days and 14 days during the Antarctic winter season in the region south of 60°S. The first EOF mode shows a nearly uniform spatial pattern in Antarctica and the Southern Ocean associated with the Antarctic Oscillation. The mode-1 intraseasonal variability of the surface temperature leads that of upper atmosphere by one day with the largest correlation at 300-hPa level geopotential heights. The intraseasonal variability of the mode-1 EOF is closely related to the variations of surface net longwave radiation the total cloud cover over Antarctica. The other major EOF modes reveal the existence of eastward propagating phases over the Southern Ocean and marginal region in Antarctica. The leading two propagating modes respond to Pacific–South American modes. Meridional winds induced by the wave train from the tropics have a direct influence on the surface air temperature over the Southern Ocean and the marginal region of the Antarctic continent.

Emerging spatial patterns in Antarctic prokaryotes

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Chun Wie eChong

2015-09-01

Full Text Available Recent advances in knowledge of patterns of biogeography in terrestrial eukaryotic organisms have led to a fundamental paradigm shift in understanding of the controls and history of life on land in Antarctica, and its interactions over the long term with the glaciological and geological processes that have shaped the continent. However, while it has long been recognized that the terrestrial ecosystems of Antarctica are dominated by microbes and their processes, knowledge of microbial diversity and distributions has lagged far behind that of the macroscopic eukaryote organisms. Increasing human contact with and activity in the continent is leading to risks of biological contamination and change in a region whose isolation has protected it for millions of years at least; these risks may be particularly acute for microbial communities which have, as yet, received scant recognition and attention. Even a matter apparently as straightforward as Protected Area designation in Antarctica requires robust biodiversity data which, in most parts of the continent, remain almost completely unavailable. A range of important contributing factors mean that it is now timely to reconsider the state of knowledge of Antarctic terrestrial prokaryotes. Rapid advances in molecular biological approaches are increasingly demonstrating that bacterial diversity in Antarctica may be far greater than previously thought, and that there is overlap in the environmental controls affecting both Antarctic prokaryotic and eukaryotic communities. Bacterial dispersal mechanisms and colonization patterns remain largely unaddressed, although evidence for regional evolutionary differentiation is rapidly accruing and, with this, there is increasing appreciation of patterns in regional bacterial biogeography in this large part of the globe. In this review, we set out to describe the state of knowledge of Antarctic prokaryote diversity patterns, drawing analogy with those of eukaryote

Long-Term Variability of Surface Albedo and Its Correlation with Climatic Variables over Antarctica

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Minji Seo

2016-11-01

Full Text Available The cryosphere is an essential part of the earth system for understanding climate change. Components of the cryosphere, such as ice sheets and sea ice, are generally decreasing over time. However, previous studies have indicated differing trends between the Antarctic and the Arctic. The South Pole also shows internal differences in trends. These phenomena indicate the importance of continuous observation of the Polar Regions. Albedo is a main indicator for analyzing Antarctic climate change and is an important variable with regard to the radiation budget because it can provide positive feedback on polar warming and is related to net radiation and atmospheric heating in the mainly snow- and ice-covered Antarctic. Therefore, in this study, we analyzed long-term temporal and spatial variability of albedo and investigated the interrelationships between albedo and climatic variables over Antarctica. We used broadband surface albedo data from the Satellite Application Facility on Climate Monitoring and data for several climatic variables such as temperature and Antarctic oscillation index (AAO during the period of 1983 to 2009. Time series analysis and correlation analysis were performed through linear regression using albedo and climatic variables. The results of this research indicated that albedo shows two trends, west trend and an east trend, over Antarctica. Most of the western side of Antarctica showed a negative trend of albedo (about −0.0007 to −0.0015 year−1, but the other side showed a positive trend (about 0.0006 year−1. In addition, albedo and surface temperature had a negative correlation, but this relationship was weaker in west Antarctica than in east Antarctica. The correlation between albedo and AAO revealed different relationships in the two regions; west Antarctica had a negative correlation and east Antarctica showed a positive correlation. In addition, the correlation between albedo and AAO was weaker in the west. This

A long term strategy for Antarctic tourism : The key to decision making within the Antarctic Treaty System?

NARCIS (Netherlands)

Bastmeijer, C.J.; Maher, P.; Stewart, E.; Lück, M.

2011-01-01

The fast increase of Antarctic tourism raises various management questions. Questions relating to the safety of tourists, questions regarding the interaction between science and tourism and questions relating to direct, indirect or cumulative affects on Antarctica's environment and wilderness

Ultimate Eocene (Priabonian) Chondrichthyans (Holocephali, Elasmobranchii) of Antarctica.

Science.gov (United States)

Kriwet, Jürgen; Engelbrecht, Andrea; Mörs, Thomas; Reguero, Marcelo; Pfaff, Cathrin

2016-01-01

The Eocene La Meseta Formation on Seymour Island, Antarctic Peninsula, is known for its remarkable wealth of fossil remains of chondrichthyans and teleosts. Chondrichthyans seemingly were dominant elements in the Antarctic Paleogene fish fauna, but decreased in abundance from middle to late Eocene, during which time remains of bony fishes increase. This decline of chondrichthyans at the end of the Eocene generally is related to sudden cooling of seawater, reduction in shelf area, and increasing shelf depth due to the onset of the Antarctic thermal isolation. The last chondrichthyan records known so far include a chimeroid tooth plate from TELM 6 (Lutetian) and a single pristiophorid rostral spine from TELM 7 (Priabonian). Here, we present new chondrichthyan records of Squalus , Squatina , Pristiophorus , Striatolamia , Palaeohypotodus , Carcharocles , and Ischyodus from the upper parts of TELM 7 (Priabonian), including the first record of Carcharocles sokolovi from Antarctica. This assemblage suggests that chondrichthyans persisted much longer in Antarctic waters despite rather cool sea surface temperatures of approximately 5°C. The final disappearance of chondrichthyans at the Eocene-Oligocene boundary concurs with abrupt ice sheet formation in Antarctica. Diversity patterns of chondrichthyans throughout the La Meseta Formation appear to be related to climatic conditions rather than plate tectonics.

Complete genome sequence of Pseudomonas antarctica PAMC 27494, a bacteriocin-producing psychrophile isolated from Antarctica.

Science.gov (United States)

Lee, Jaejin; Cho, Yong-Joon; Yang, Jae Young; Jung, You-Jung; Hong, Soon Gyu; Kim, Ok-Sun

2017-10-10

Antimicrobial-producing, cold-adapted microorganisms have great potential for biotechnological applications in food, pharmaceutical, and cosmetic industries. Pseudomonas antarctica PAMC 27494, a psychrophile exhibiting antimicrobial activity, was isolated from an Antarctic freshwater sample. Here we report the complete genome of P. antarctica PAMC 27494. The strain contains a gene cluster encoding microcin B which inhibits DNA regulations by targeting the DNA gyrase. PAMC 27494 may produce R-type pyocins and also contains a complete set of proteins for the biosynthesis of adenosylcobalamin and possibly induces plant growth by supplying pyrroloquinoline quionone molecules. Copyright © 2017 Elsevier B.V. All rights reserved.

Deglacial temperature history of West Antarctica

Science.gov (United States)

Cuffey, Kurt M.; Clow, Gary D.; Steig, Eric J.; Buizert, Christo; Fudge, T.J.; Koutnik, Michelle; Waddington, Edwin D.; Alley, Richard B.; Severinghaus, Jeffrey P.

2016-01-01

The most recent glacial to interglacial transition constitutes a remarkable natural experiment for learning how Earth’s climate responds to various forcings, including a rise in atmospheric CO2. This transition has left a direct thermal remnant in the polar ice sheets, where the exceptional purity and continual accumulation of ice permit analyses not possible in other settings. For Antarctica, the deglacial warming has previously been constrained only by the water isotopic composition in ice cores, without an absolute thermometric assessment of the isotopes’ sensitivity to temperature. To overcome this limitation, we measured temperatures in a deep borehole and analyzed them together with ice-core data to reconstruct the surface temperature history of West Antarctica. The deglacial warming was 11.3±1.8∘">11.3±1.8∘11.3±1.8∘C, approximately two to three times the global average, in agreement with theoretical expectations for Antarctic amplification of planetary temperature changes. Consistent with evidence from glacier retreat in Southern Hemisphere mountain ranges, the Antarctic warming was mostly completed by 15 kyBP, several millennia earlier than in the Northern Hemisphere. These results constrain the role of variable oceanic heat transport between hemispheres during deglaciation and quantitatively bound the direct influence of global climate forcings on Antarctic temperature. Although climate models perform well on average in this context, some recent syntheses of deglacial climate history have underestimated Antarctic warming and the models with lowest sensitivity can be discounted.

Aquatic wing flapping at low Reynolds numbers: swimming kinematics of the Antarctic pteropod, Clione antarctica.

Science.gov (United States)

Borrell, Brendan J; Goldbogen, Jeremy A; Dudley, Robert

2005-08-01

We studied swimming kinematics of the Antarctic pteropod, Clione antarctica, to investigate how propulsive forces are generated by flexible oscillating appendages operating at low Reynolds numbers (10stroke of flapping consisted of distinct power and recovery phases, which were of approximately equal duration in both the upstroke and the downstroke. As pteropods ascended, the body traced a sawtooth path when viewed laterally. The magnitude of these oscillations decreased with body mass, and larger animals (operating at Re>25) exhibited gliding during the recovery phase of each half-stroke. Maximum translational and rotational accelerations of the body occurred at the initiation of each power phase, suggesting that rotational circulation, the acceleration reaction, and wake recapture may all potentially contribute to vertical force production. Individual contributions of these mechanisms cannot, however, be assessed from these kinematic data alone. During recovery phases of each half-stroke, C. antarctica minimized adverse drag forces by orienting the wings parallel to flow and by moving them along the body surface, possibly taking advantage of boundary layer effects. Vertical force production was altered through changes in the hydrodynamic angle of attack of the wing that augmented drag during the power phase of each half-stroke. At higher translational velocities of the body, the inclination of the power phase also became more nearly vertical. These results indicate that, in addition to serotonin-mediated modulation of wingbeat frequency reported previously in Clione, geometric alteration of wingbeat kinematics offers a precise means of controlling swimming forces.

Unexpected effects of climate change on the predation of Antarctic petrels

NARCIS (Netherlands)

Franeker, van J.A.; Creuwels, J.C.S.; Veer, van der W.; Cleland, S.; Robertson, G.

2001-01-01

Antarctic petrels Thalassoica antarctica on Ardery Island, Antarctica (66°S, 110°E), experienced major reductions in breeding success and breeder survival over four seasons between 1984/85 and 1996/97. In 1996 the reason was revealed. A large snowdrift covered part of the study colony on the cliffs.

Hydrogeological characteristics of aquifer near Arctowski Polish Antarctic Station on King George Island (South Shetland Islands), Antarctica

Science.gov (United States)

Krogulec, Ewa; Krogulec, Tomasz; Małecki, Jerzy; Pietrzykowski, Paweł; Dobak, Paweł

2018-06-01

During the Antarctic summer season of 2015/2016, the groundwater studies were performed in the area of Henryk Arctowski Polish Antarctic Station on King George Island (South Shetland Islands) in Admiralty Bay of Antarctica. Rock and groundwater samples were collected from 14 research excavations down to a depth of 0.8-2.5 m b.g.l. Analyses of surface waters were performed on water samples from streams, mossland, and a drinking water reservoir. The scope of hydrochemical studies comprised analyses of temperature, pH, mineralization, phosphates, nitrates, macroelements and selected microelements. Using empirical formulas, granulometric analysis of rock samples from various depths, measurements of sample moisture, and calculations of the hydraulic conductivity were performed. The groundwater is poorly mineralized, representing chloride-sulfate-bicarbonate-sodium and chloride-bicarbonate-sodium-calcium types. Studies on hydrochemical indicators show a small range of the effect of animal ecosystems on the waters; no effects of organic matter have been identified in the study area. Results of hydrogeochemical studies of waters and observations of groundwater levels in the summer season indicate groundwater recharge in a shallow groundwater circulation system, lateral inflow direction from land toward the seashore, and a low rate of rainwater infiltration. Groundwater drainage occurs through evapotranspiration and water runoff to the sea.

Results and Error Estimates from GRACE Forward Modeling over Antarctica

Science.gov (United States)

Bonin, Jennifer; Chambers, Don

2013-04-01

Forward modeling using a weighted least squares technique allows GRACE information to be projected onto a pre-determined collection of local basins. This decreases the impact of spatial leakage, allowing estimates of mass change to be better localized. The technique is especially valuable where models of current-day mass change are poor, such as over Antarctica. However when tested previously, the least squares technique has required constraints in the form of added process noise in order to be reliable. Poor choice of local basin layout has also adversely affected results, as has the choice of spatial smoothing used with GRACE. To develop design parameters which will result in correct high-resolution mass detection and to estimate the systematic errors of the method over Antarctica, we use a "truth" simulation of the Antarctic signal. We apply the optimal parameters found from the simulation to RL05 GRACE data across Antarctica and the surrounding ocean. We particularly focus on separating the Antarctic peninsula's mass signal from that of the rest of western Antarctica. Additionally, we characterize how well the technique works for removing land leakage signal from the nearby ocean, particularly that near the Drake Passage.

78 FR 54686 - Notice of Permit Applications Received under the Antarctic Conservation Act of 1978

Science.gov (United States)

2013-09-05

... the Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism... of the ongoing effort to monitor the spatial scale of human impacts in Antarctica. Samples taken near...

Parasites of the Antarctic toothfish (Dissostichus mawsoni Norman, 1937 (Perciformes, Nototheniidae in the Pacific sector of the Antarctic

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Ilya I. Gordeev

2016-06-01

Full Text Available The Antarctic toothfish (Dissostichus mawsoni Norman, 1937 is one of the main target species of commercial fisheries in the Antarctic. It is an endemic and is found along the shelf of Antarctica, as well as on the slopes of seamounts, underwater elevations and islands in the sub-Antarctic. It feeds on a variety of fish and cephalopods and can be an intermediate/paratenic host of some helminthes, whose final hosts are whales, seals, large rays and sharks. This article presents new data on toothfish infection in the Pacific sector of the Antarctic. Specimens were examined during commercial longline fishing in the Ross Sea and the Amundsen Sea in January–February 2013. Fourteen species of parasites were found using standard parasitological methods and genetic analysis.

Pricia antarctica gen. nov., sp. nov., a member of the family Flavobacteriaceae, isolated from Antarctic intertidal sediment.

Science.gov (United States)

Yu, Yong; Li, Hui-Rong; Zeng, Yin-Xin; Sun, Kun; Chen, Bo

2012-09-01

A yellow-coloured, rod-shaped, Gram-reaction- and Gram-staining-negative, non-motile and aerobic bacterium, designated strain ZS1-8(T), was isolated from a sample of sandy intertidal sediment collected from the Antarctic coast. Flexirubin-type pigments were absent. In phylogenetic analyses based on 16S rRNA gene sequences, strain ZS1-8(T) formed a distinct phyletic line and the results indicated that the novel strain should be placed in a new genus within the family Flavobacteriaceae. In pairwise comparisons between strain ZS1-8(T) and recognized species, the levels of 16S rRNA gene sequence similarity were all antarctica gen. nov., sp. nov. is proposed. The type strain of the type species is ZS1-8(T) (= JCM 17291(T) = DSM 23421(T)).

Assessing the effectiveness of specially protected areas for conservation of Antarctica's botanical diversity.

Science.gov (United States)

Hughes, Kevin A; Ireland, Louise C; Convey, Peter; Fleming, Andrew H

2016-02-01

Vegetation is sparsely distributed over Antarctica's ice-free ground, and distinct plant communities are present in each of the continent's 15 recently identified Antarctic Conservation Biogeographic Regions (ACBRs). With rapidly increasing human activity in Antarctica, terrestrial plant communities are at risk of damage or destruction by trampling, overland transport, and infrastructure construction and from the impacts of anthropogenically introduced species, as well as uncontrollable pressures such as fur seal (Arctocephalus gazella) activity and climate change. Under the Protocol on Environmental Protection to the Antarctic Treaty, the conservation of plant communities can be enacted and facilitated through the designation of Antarctic Specially Protected Areas (ASPAs). We examined the distribution within the 15 ACBRs of the 33 ASPAs whose explicit purpose includes protecting macroscopic terrestrial flora. We completed the first survey using normalized difference vegetation index (NDVI) satellite remote sensing to provide baseline data on the extent of vegetation cover in all ASPAs designated for plant protection in Antarctica. Large omissions in the protection of Antarctic botanical diversity were found. There was no protection of plant communities in 6 ACBRs, and in another 6, area was included in an ASPA that protected vegetation. Protected vegetation cover within the 33 ASPAs totaled 16.1 km(2) for the entire Antarctic continent; over half was within a single protected area. Over 96% of the protected vegetation was contained in 2 ACBRs, which together contributed only 7.8% of the continent's ice-free ground. We conclude that Antarctic botanical diversity is clearly inadequately protected and call for systematic designation of ASPAs protecting plant communities by the Antarctic Treaty Consultative Parties, the members of the governing body of the continent. © 2015 The Authors. Conservation Biology published by Wiley Periodicals, Inc. on behalf of Society

The controlled ecological life support system Antarctic analog project: Analysis of wastewater from the South Pole Station, Antarctica, volume 1

Science.gov (United States)

Flynn, Michael T.; Bubenheim, David L.; Straight, Christian L.; Belisle, Warren

1994-01-01

The Controlled Ecological Life Support system (CELSS) Antarctic Analog Project (CAAP) is a joint National Science Foundation (NSF) and NASA project for the development, deployment and operation of CELSS technologies at the Amundsen-Scott South Pole Station. NASA goals are operational testing of CELSS technologies and the conduct of scientific studies to facilitate technology selection and system design. The NSF goals are that the food production, water purification, and waste treatment capabilities which will be provided by CAAP will improve the quality of life for the South Pole inhabitants, reduce logistics dependence, and minimize environmental impacts associated with human presence on the polar plateau. This report presents an analysis of wastewater samples taken from the Amundsen-Scott South Pole Station, Antarctica. The purpose of the work is to develop a quantitative understanding of the characteristics of domestic sewage streams at the South Pole Station. This information will contribute to the design of a proposed plant growth/waste treatment system which is part of the CELSS Antarctic Analog Project (CAAP).

Intraplate Earthquakes and Deformation within the East Antarctic Craton

Science.gov (United States)

Lough, A. C.; Wiens, D.; Nyblade, A.

2017-12-01

The apparent lack of tectonic seismicity within Antarctica has long been discussed. Explanations have ranged from a lack of intraplate stress due to the surrounding spreading ridges and low absolute plate velocity (Sykes, 1978), to the weight of ice sheets increasing the vertical normal stress (Johnston, 1987). The 26 station GAMSEIS/AGAP array deployed in East Antarctica from late 2008 to early 2010 provides the first opportunity to study the intraplate seismicity of the Antarctic interior using regional data. Here we report 27 intraplate tectonic earthquakes that occurred during 2009. Depth determination together with their corresponding uncertainty estimates, show that most events originate in the shallow to middle crust, indicating a tectonic and not a cryoseismic origin. The earthquakes are primarily located beneath linear alignments of basins adjacent to the Gamburtsev Subglacial Mountains (GSM) that have been denoted as the East Antarctic rift system (Ferraccioli et al, 2011). The geophysical properties of the `rift' system contrast sharply with those of the GSM and Vostok Subglacial Highlands on either side. Crustal thickness, seismic velocity, and gravity anomalies all indicate large lateral variation in lithospheric properties. We propose the events outline an ancient continental rift, a terrain boundary feature, or a combination of the two where rifting exploited pre-existing weakness. It is natural to draw parallels between East Antarctica and the St. Lawrence depression where rifting and a collisional suture focus intraplate earthquakes within a craton (Schulte and Mooney, 2005). We quantify the East Antarctic seismicity by developing a frequency-magnitude relation, constraining the lower magnitudes with the 2009 results and the larger magnitudes with 1982-2012 teleseismic seismicity. East Antarctica and the Canadian Shield show statistically indistinguishable b-values (near 1) and seismicity rates as expressed as the number of events with mb > 4 per

Book review: The future of Antarctica

Science.gov (United States)

Behrendt, John C.

1991-01-01

A conference on Antarctica: an Exploitable Resource too Valuable to Develop? took place at the Sir Robert Menzies Centre for Australian studies at the University of London in either late 1989 or early 1990. The papers were compiled into this small book (only 104 pages of text exclusive of useful appendices containing maps, texts of the Antarctic treaty and the Convention on the regulation of Antarctic Mineral Resource Activity [CRAMRA]) which addresses the hottest issues confronting the Antarctic Treaty Consultative Parties in the early 1990’s. Some of the discussion is being overtaken by events, but fortunately, the general quality and broadness of the coverage will make the book useful to diplomats, historians, international lawyers, scientists and other environmentalists for some time to come.

Coastal-change and glaciological maps of Antarctica

Science.gov (United States)

Williams, Richard S.

2004-01-01

Changes in the area and volume of polar ice sheets are intricately linked to changes in global climate, and the resulting changes in sea level may severely impact the densely populated coastal regions on Earth. Melting of the West Antarctic part alone of the Antarctic ice sheet could cause a sea-level rise of approximately 6 meters (m). The potential sea-level rise after melting of the entire Antarctic ice sheet is estimated to be 65 m (Lythe and others, 2001) to 73 m (Williams and Hall, 1993). In spite of its importance, the mass balance (the net volumetric gain or loss) of the Antarctic ice sheet is poorly known; it is not known for certain whether the ice sheet is growing or shrinking. In a review paper, Rignot and Thomas (2002) concluded that the West Antarctic part of the Antarctic ice sheet is probably becoming thinner overall; although the western part is thickening, the northern part is thinning. Joughin and Tulaczyk (2002), based on analysis of ice-flow velocities derived from synthetic aperture radar, concluded that most of the Ross ice streams (ice streams on the east side of the Ross Ice Shelf) have a positive mass balance. The mass balance of the East Antarctic is unknown, but thought to be in near equilibrium. Measurement of changes in area and mass balance of the Antarctic ice sheet was given a very high priority in recommendations by the Polar Research Board of the National Research Council (1986), in subsequent recommendations by the Scientific Committee on Antarctic Research (SCAR) (1989, 1993), and by the National Science Foundation's (1990) Division of Polar Programs. On the basis of these recommendations, the U.S. Geological Survey (USGS) decided that the archive of early 1970s Landsat 1, 2, and 3 Multispectral Scanner (MSS) images of Antarctica and the subsequent repeat coverage made possible with Landsat and other satellite images provided an excellent means of documenting changes in the coastline of Antarctica (Ferrigno and Gould, 1987). The

The use of epilithic Antarctic lichens (Usnea aurantiacoatra and U. antartica) to determine deposition patterns of heavy metals in the Shetland Islands, Antarctica.

Science.gov (United States)

Poblet, A; Andrade, S; Scagliola, M; Vodopivez, C; Curtosi, A; Pucci, A; Marcovecchio, J

1997-11-27

Trace-metal contents were recorded for the epilithic antarctic lichens Usnea aurantiacoatra and U. antartica, sampled close to the Argentine scientific station 'Jubany' on '25 de Mayo' (King George) Island, in the Southern Shetland Archipelago (Antarctica). The corresponding heavy-metal levels have been measured through atomic absorption spectrophotometry, following internationally accepted analytical methods. The results obtained support the hypothesis that an atmospheric circulation of trace metals exists on the assessed area, and the activities developed at the different scientific stations located on this island would be a potential source of heavy metals to the evaluated environment. The geographical distribution of trace metals atmospherically transported in the area close to 'Jubany Station' was studied through the corresponding metal contents of the assessed lichens. Finally, the suitability of both analyzed lichen species, Usnea aurantiacoatra and U. antartica, as biological indicators for quantitative monitoring of airborne metals for this antarctic environment was recognized.

Photoadaptations of photosynthesis and carbon metabolism by phytoplankton from McMurdo Sound, Antarctica. I. Species-specific and community responses to reduced irradiances

International Nuclear Information System (INIS)

Rivkin, R.B.; Voytek, M.A.

1987-01-01

Irradiance-dependent rates of photosynthesis and photosynthate labeling patterns were measured for phytoplankton in McMurdo Sound, Antarctica. Species-specific and traditional whole-water techniques were used to compare the physiological responses of algae collected in a high light environment at the ice edge and from a low light environment under the annual sea ice. There were differences among species within the same sample, for the same species isolated from high and low light environments, and when species-specific responses were compared with that of the natural assemblage. For algae collected beneath the sea ice, photosynthesis generally saturated at a lower irradiance, and the light-limited region of the P vs. I relationship had a steeper slope than for the same species collected at the ice edge. Low-light-adapted algae incorporated significantly less 14 C into proteins and more into low molecular weight compounds and lipids than the same species isolated from a high light environment. Under conditions where reduced rates of protein synthesis were coupled with high rates of carbon uptake, the measurement of photosynthesis may not accurately reflect the physiological condition of the phytoplankton

Coastal-change and glaciological map of the Bakutis Coast, Antarctica: 1972-2002

Science.gov (United States)

Swithinbank, Charles; Williams, Richard S.; Ferrigno, Jane G.; Foley, Kevin M.; Rosanova, Christine E.

2003-01-01

Changes in the area and volume of the polar ice sheets are intricately linked to changes in global climate, and the resulting changes in sea level may severely impact the densely populated coastal regions on Earth. Loss of the West Antarctic part of the Antarctic ice sheet alone could cause a sea-level rise of approximately 6 m. The potential sea-level rise after melting of the entire Antarctic ice sheet is estimated to be 65 m to 73 m. In spite of its importance, the mass balance (the net volumetric gain or loss) of the Antarctic ice sheet is poorly known; it is not known whether the ice sheet is growing or shrinking. As a result, measurement of changes in the Antarctic ice sheet was given a very high priority in recommendations by the Polar Research Board of the National Research Council (1986), by the Scientific Committee on Antarctic Research (SCAR) (1989), and by the National Science Foundation's (1990) Division of Polar Programs. An archive of early 1970's Landsat 1, 2, and 3 Multispectral Scanner (MSS) images of Antarctica and the fact that the repeat coverage with satellite images provided an excellent means of documenting changes in the coastline of Antarctica provided the impetus for carrying out a comprehensive analysis of the glaciological features of the coastal regions and changes in ice fronts of Antarctica. The project was later modified to include Landsat 4 and 5 MSS and Thematic Mapper (TM) and RADARSAT images to compare changes over a 20- to 25- year time interval and to prepare a series of 24 1:1,000,000-scale and 1 1:5,000,000-scale U.S. Geological Survey Geologic Investigations Series Maps ('I-Maps') (Williams and others, 1995; Williams and Ferrigno, 1998; and Ferrigno and others, 2002) in both paper and digital format.

South African Antarctic research programme 1978-1982

CSIR Research Space (South Africa)

SASCAR

1978-12-01

Full Text Available This document provides a comprehensive review of the planned South African scientific activities in Antarctica and on the sub-Antarctic islands in the five year period starting in 1978. The scientific programmes are classified under five headings...

CEDEX research activities in Antarctica. Aquatic ecosystems in Byers Peninsula (Livingston Island, maritime Antarctica); Actividad investigadora del CEDEX en la Antartida. Ecosistemas acuaticos de la Peninsula Byers (Isla Livingston, Antartida)

Energy Technology Data Exchange (ETDEWEB)

Toro, M.; Quesada, A.; Camacho, A.; Oliva, M.; Alcami, A.; Antoniades, D.; Banon, M.; Fassnacht, S.; Fernandez-Valiente, E.; Galan, L.; Giralt, S.; Granados, I.; Justel, A.; Liu, E. J.; Lopez-Bravo, A.; Martinez-Cortizas, A.; Pla-Rabes, S.; Rastrojo, A.; Rico, E.; Rochera, C.; Van de Vijver, B.; Velazquez, D.; Villaescusa, J. A.; Vicent, W. F.

2015-07-01

Since 2001 CEDEX has taken part in many Antarctic joint research projects with different institutions from Spain and other countries, developing scientific activities in the International Camp of Byers Peninsular (Livingston Island, South Shetland Islands, Antarctica). This place was designed as an Antarctic Specially Protected Area (No.126) because the importance and value of its terrestrial and aquatic habitats. It is one of the largest ice-free areas of maritime Antarctica, with the highest diversity of environments and geological, hydrological and biological processes in the whole region, all of them in a pristine state. Byers Peninsula is considered the most significant limnological area in the Antarctic Peninsula region because it hosts a high number of lakes, ponds and streams, with an exceptional fauna and flora diversity, including the most singular, representative or endemic Antarctic species. Furthermore, the lakes sedimentary record is one of the widest and complete archives in Antarctic Peninsula region for the palaeocological and climatic study of the Holocene. Because Byers Peninsula is an Antarctic biodiversity hotspot, and it is located in one of the areas in the Earth where global warming is being more significant, it must be considered as a suitable international reference site for limnetic, terrestrial and coastal studies, and long term monitoring programmes. (Author)

Humus in some soils from Western Antarctica

Science.gov (United States)

Abakumov, E.

2009-04-01

Soils of Antarctica are well known as a thick profile soils with low amounts of humus concentrated in the upper layers - O or A horizons. Also there are specific soils of seashore landscapes which affected by penguins guano accumulation and, therefore characterized by high stocks of organic matter in solum. These two types of soils were studied during the Western Antarctica part of 53th Russian Antarctic Expedition in 2008 International Polar Year. These rote of expedition was on Polar stations "Russkaya", "Leningradskaya" and "Bellinsgausen" and also two places, not affected by polar men's - Lindsey Island and Hudson mountains (Ross Sea). Typical soils of "Russkaya" and "Leningradskaya" stations was a Cryosoils with low humus content (0,02 - 0,20 %) which was a product of lichens decaying and further humification. The humus profile was not deep and humic substances migration stopped on the 30 cm deeps maximally. Soils of Sub-Antarctica (Bellinsgausen station, King-George Island) show higher portions of humus which maximum was 3,00 % under the mosses. Humus distribution was more gradual through profile due to the higher thickness of active layer and longer period of biological activity. Soils under the penguin's beaches shows big portions of organic matter, in some cases more than 50 % to total soil mass. Humification starts in first years in cases of Sub-Antarctic guano soils and only after 3-7 years of leaching in seashore Antarctic guano-soils. Soils under the guano layers were extremely reached by nitrogen, and in some cases there were not any plants there due to toxicity of guano. This event was more typical for cold seashore soils of Antarctica. In all cases humus consists mostly of fulvic acids and low molecular non-specific organic acids. The CHA/CFA ratio in all cases were lesser than 1,0 and in more that 50 % of cases it was lesser than 0,5. The investigations conducted shows that the stocks of humus in soil of Antarctica are not estimated and till now we

The genus Bryoerythrophyllum (Musci, Pottiaceae in Antarctica

Directory of Open Access Journals (Sweden)

Sollman Philip

2015-07-01

Full Text Available Antarctic material of the genus Bryoerythrophyllum P. C. Chen was studied from all specimens present in KRAM. Bryoerythrophyllum recurvirostrum (Hedw. P. C. Chen var. antarcticum L. I. Savicz & Smirnova is treated as a distinct species: B. antarcticum (L. I. Savicz & Smirnova P. Sollman, stat. nov. Three species are now known in the Antarctic region: B. antarcticum, B. recurvirostrum and B. rubrum (Jur. ex Geh. P. C. Chen. Bryoerythrophyllum rubrum is reported for the first time from the Antarctic. It is a bipolar species. A key to the taxa is given. These species are described and briefly discussed, with notes on illustrations, reproduction, habitat, world range, distribution and elevation in Antarctica.

Melting empires? Climate change and politics in Antarctica since the International Geophysical Year.

Science.gov (United States)

Howkins, Adrian

2011-01-01

This article examines the relationship between climate change and politics in Antarctica since the International Geophysical Year of 1957-8, paying particular attention to the work of the British Antarctic Survey. Research conducted in Antarctica has played an important role in the understanding of climate change on a global scale. In turn, fears about the consequences of global climate change have radically changed perceptions of Antarctica and profoundly shaped scientific research agendas: a continent that until fifty years ago was perceived largely as an inhospitable wilderness has come to be seen as a dangerously vulnerable environment. This radical shift in perception contrasts with a fundamental continuity in the political power structures of the continent. This article argues that the severity of the threat of climate change has reinforced the privileged political position of the "insider" nations within the Antarctic Treaty System.

Estimating Antarctic Geothermal Heat Flux using Gravity Inversion

Science.gov (United States)

Vaughan, Alan P. M.; Kusznir, Nick J.; Ferraccioli, Fausto; Leat, Phil T.; Jordan, Tom A. R. M.; Purucker, Michael E.; Golynsky, A. V.; Sasha Rogozhina, Irina

2013-04-01

Geothermal heat flux (GHF) in Antarctica is very poorly known. We have determined (Vaughan et al. 2012) top basement heat-flow for Antarctica and adjacent rifted continental margins using gravity inversion mapping of crustal thickness and continental lithosphere thinning (Chappell & Kusznir 2008). Continental lithosphere thinning and post-breakup residual thicknesses of continental crust determined from gravity inversion have been used to predict the preservation of continental crustal radiogenic heat productivity and the transient lithosphere heat-flow contribution within thermally equilibrating rifted continental and oceanic lithosphere. The sensitivity of present-day Antarctic top basement heat-flow to initial continental radiogenic heat productivity, continental rift and margin breakup age has been examined. Knowing GHF distribution for East Antarctica and the Gamburtsev Subglacial Mountains (GSM) region in particular is critical because: 1) The GSM likely acted as key nucleation point for the East Antarctic Ice Sheet (EAIS); 2) the region may contain the oldest ice of the EAIS - a prime target for future ice core drilling; 3) GHF is important to understand proposed ice accretion at the base of the EAIS in the GSM and its links to sub-ice hydrology (Bell et al. 2011). An integrated multi-dataset-based GHF model for East Antarctica is planned that will resolve the wide range of estimates previously published using single datasets. The new map and existing GHF distribution estimates available for Antarctica will be evaluated using direct ice temperature measurements obtained from deep ice cores, estimates of GHF derived from subglacial lakes, and a thermodynamic ice-sheet model of the Antarctic Ice Sheet driven by past climate reconstructions and each of analysed heat flow maps, as has recently been done for the Greenland region (Rogozhina et al. 2012). References Bell, R.E., Ferraccioli, F., Creyts, T.T., Braaten, D., Corr, H., Das, I., Damaske, D., Frearson, N

Recent Aeromagnetic Anomaly views of the Antarctic continent

Science.gov (United States)

Ferraccioli, F.

2012-04-01

Antarctica is a keystone within the Gondwana and Rodinia supercontinents. However, despite intense geological research along the coastal fringes of Antarctica, the interior of the continent remains one of the most poorly understood regions on Earth. Aeromagnetic investigations are a useful tool to help disclose the structure and the evolution of continents from the Precambrian to the Cenozoic and Antarctica is no exception. Here I review a variety of aeromagnetic studies in East and West Antarctica performed since the completion of the first generation ADMAP -Antarctic Digital Magnetic Anomaly Project- in 2001. In western Dronning Maud, in East Antarctica, aeromagnetic data help delineate the extent of the Jurassic Jutulstraumen subglacial rift that is flanked by remnants of a Grenvillian-age (ca 1.1. Ga) igneous province and magmatic arc. Different magnetic signatures appear to characterize the Coats Land block but reconnaissance surveys are insufficient to fully delineate the extent and significance of the Coats Land block, a possible tectonic tracer of Laurentia within Rodinia (Loewy et al., 2011). Further in the interior of East Antarctica, a mosaic of distinct and hitherto largely unknown Precambrian provinces has recently been revealed by combining aeromagnetic and satellite magnetic data with models of crustal thickness constrained by gravity modeling and seismology (Ferraccioli et al., 2011, Nature). A major collisional suture may lie between the Archean Ruker Province and an inferred Proterozoic Gamburtsev Province but the age of final assembly of central East Antarctica remains uncertain and controversial. I favour a Grenville-age collisional event (linked to Rodinia assembly) or possibly older Paleoproteroic collision, followed by intraplate reactivation, as opposed to Neoproterozoic or Early Cambrian collision linked to East-West Gondwana assembly (Boger, 2011). New aerogeophysical surveys over Prince Elizabeth and Queen Mary Land could test this

Antarctic 20th Century Accumulation Changes Based on Regional Climate Model Simulations

Directory of Open Access Journals (Sweden)

Klaus Dethloff

2010-01-01

investigated on the basis of ERA-40 data and HIRHAM simulations. It is shown that the regional accumulation changes are largely driven by changes in the transient activity around the Antarctic coasts due to the varying AAO phases. During positive AAO, more transient pressure systems travelling towards the continent, and Western Antarctica and parts of South-Eastern Antarctica gain more precipitation and mass. Over central Antarctica the prevailing anticyclone causes a strengthening of polar desertification connected with a reduced surface mass balance in the northern part of East Antarctica.

The role of the protected area concept in protecting the world’s largest natural reserve: Antarctica

Directory of Open Access Journals (Sweden)

Kees Bastmeijer

2009-06-01

Full Text Available Should the entire Antarctic continent and the surrounding islands be recognised as a ‘protected area’ or as a continent where certain areas, just like anywhere else, may be designated as protected areas? To find an answer to this question, this paper first discusses the most important agreements and declarations on environmental protection in Antarctica. Next, these instruments are compared with the components of IUCN’s ‘protected area’ definition (2008. In the light of this overall protection of Antarctica, the instrument of designating areas as Antarctic Specially Protected Areas (ASPAs is discussed on the basis of a quick scan of 42 management plans for existing ASPAs. It is concluded that Antarctica could indeed be considered as a protected area and that the ASPA instrument is so shaped to provide specific areas with ‘extra protection’ by regulating human activities in those areas with a high level of detail. However, the continuous increase in human activities in Antarctica raises concerns with respect to the scope and completeness of the existing legal instruments. These concerns regarding the overall protection of Antarctica could become an argument for applying the ASPA instrument in respect of larger areas to ensure the comprehensive protection of at least certain parts of Antarctica. This would make the ASPA system more comparable with protected area systems in other parts of the world; however, strengthening the overall protection of Antarctica – parallel to the further development of the ‘specially’ protected area system - would be more consistent with Antarctica’s protected status as has developed since the Antarctic Treaty was signed 50 years ago.

Atmospheric CO2 concentrations and (delta)13C values across the Antarctic Circumpolar Current between New Zealand and Antarctica

International Nuclear Information System (INIS)

Longinelli, Antonio; Selmo, Enricomaria; Giglio, Federico; Langone, Leonardo; Lenaz, Renzo; Ori, Carlo

2007-01-01

Measurements of atmospheric CO 2 concentrations were repeatedly carried out on the vessel 'Italica' of the Italian National Research Program in Antarctica, during cruises from Italy to Antarctica. Discrete air samples were also collected in 4-L Pyrex flasks during these cruises in order to carry out (delta) 13 C analyses on atmospheric CO 2 . The results acquired between New Zealand and Antarctica are reported here. The mean growth rate of the CO 2 concentration from 1996 to 2003 in this area of the Southern Oceans is of about 1.8 ppmv/yr, in good agreement with NOAA/CMDL measurements. The rates of increase from cruise to cruise are rather variable. From 1996-1997 to 1998-1999 cruise the yearly growth rate is 2.75 ppmv/yr, close to the large growth rates measured in several areas and mainly related to the most severe El Nino event of the last years. The other yearly growth rates are of about 1.3 and 2 ppmv for the periods 1998-1999 to 2001-2002 and 2001-2002 to 2003-2004, respectively. The large difference between these two values is probably related to the uncertainty on the only two 2001-2002 discrete measurements of CO 2 concentration in this area. The measured (delta) 13 C values show two completely different distributions and a large interannual variability. The 1998-1999, 2002-2003, and 2003-2004 results obtained between about 55 deg S and 65 deg S across the Antarctic Polar Front show a marked negativization of up to more than 0.2% when compared to the background values. The results are related to local source regions of CO 2 , as frequently found in the Southern Ocean by several authors; the negative (delta) 13 C values are tentatively related to the possible contribution of different causes. Among them, the southward negative gradient of (delta) 13 C of the dissolved inorganic carbon, the contribution from upwelling deep waters and from subsurface processes between the Northern SubAntarctic Front and the Polar Front, and, partly, the contribution of CO 2

Challenges in protecting the wilderness of Antarctica

Science.gov (United States)

Tina Tin; Alan Hemmings

2011-01-01

Since 1998, the wilderness values of Antarctica have been among those given legal recognition under the Protocol on Environmental Protection to the Antarctic Treaty. Despite the legal obligation, on-the-ground implementation has attracted little interest. The term "wilderness" and its consequential operational implication, including the designation of...

Palaeomagnetism and K-Ar age of Mesozoic and Cenozoic igneous rocks from Antarctica

International Nuclear Information System (INIS)

Valencio, D.A.; Mendia, J.E.; Vilas, J.F.

1979-01-01

A new analysis of palaeomagnetic data for igneous rocks from Deception Island, 25 de Mayo Island (King George Island) and Cape Spring, are given. K-Ar age determinations indicate that most of the igneous samples from 25 de Mayo Island included in the palaeomagnetic study are of Late Mesozoic/Early Tertiary age. The significance of these palaeomagnetic-radiometric data on the hypothesis of oroclinal bending of the Antarctic Peninsula and on the apparent polar movement of Antarctica is discussed. The positions of palaeomagnetic poles for the Andean igneous complex indicate that there has not been any apparent post-Late Cretaceous/Early Tertiary oroclinal bending in the Antarctic Peninsula from 74 0 S to 62 0 S. A comparison of the positions of palaeomagnetic poles for Antarctica and Australia suggests that the direction of apparent polar movement relative to Antarctica reversed after the Miocene. (Auth.)

Spatial and temporal variability across life's hierarchies in the terrestrial Antarctic.

Science.gov (United States)

Chown, Steven L; Convey, Peter

2007-12-29

Antarctica and its surrounding islands lie at one extreme of global variation in diversity. Typically, these regions are characterized as being species poor and having simple food webs. Here, we show that terrestrial systems in the region are nonetheless characterized by substantial spatial and temporal variations at virtually all of the levels of the genealogical and ecological hierarchies which have been thoroughly investigated. Spatial variation at the individual and population levels has been documented in a variety of genetic studies, and in mosses it appears that UV-B radiation might be responsible for within-clump mutagenesis. At the species level, modern molecular methods have revealed considerable endemism of the Antarctic biota, questioning ideas that small organisms are likely to be ubiquitous and the taxa to which they belong species poor. At the biogeographic level, much of the relatively small ice-free area of Antarctica remains unsurveyed making analyses difficult. Nonetheless, it is clear that a major biogeographic discontinuity separates the Antarctic Peninsula and continental Antarctica, here named the 'Gressitt Line'. Across the Southern Ocean islands, patterns are clearer, and energy availability is an important correlate of indigenous and exotic species richness, while human visitor numbers explain much of the variation in the latter too. Temporal variation at the individual level has much to do with phenotypic plasticity, and considerable life-history and physiological plasticity seems to be a characteristic of Antarctic terrestrial species. Environmental unpredictability is an important driver of this trait and has significantly influenced life histories across the region and probably throughout much of the temperate Southern Hemisphere. Rapid climate change-related alterations in the range and abundance of several Antarctic and sub-Antarctic populations have taken place over the past several decades. In many sub-Antarctic locations, these

The influence of some environmental factors on cytological and biometric parameters and chlorophyll content of Deschampsia antarctica Desv. in the maritime Antarctic.

Science.gov (United States)

Parnikoza, I Yu; Loro, P; Miryuta, N Yu; Kunakh, V A; Kozeretska, I A

2011-01-01

Under the environmental conditions of the Point Thomas Oasis (King George Island, the South Shetland Islands), we studied the influence of month-long artificial treatment with fresh water, salt water, and guano solution on the biometric characteristics, chlorophyll content, as well as the nuclear area of leaf parenchymal cells and nuclear DNA content, in a maritime Antarctic aboriginal plant Deschampsia antarctica. The modeled factors induced an increase in the generative shoot height and the length of the largest leaf, but did not influence the number of flowers. Treatment with guano caused an increase in the chlorophyll a and b contents, while fresh water treatment only led to some increase in chlorophyll a. Fluctuations of physiologically significant traits, such as the nuclear area and DNA content in the leaf parenchyma cells of D. antarctica, have been traced under the influence of the studied factors. Understanding of the hierarchy of influence of these factors as well as and sensitivity of plants of this species to external agents require further investigation.

Eocene squalomorph sharks (Chondrichthyes, Elasmobranchii) from Antarctica

Science.gov (United States)

Engelbrecht, Andrea; Mörs, Thomas; Reguero, Marcelo A.; Kriwet, Jürgen

2017-10-01

Rare remains of predominantly deep-water sharks of the families Hexanchidae, Squalidae, Dalatiidae, Centrophoridae, and Squatinidae are described from the Eocene La Meseta Formation, Seymour Island, Antarctic Peninsula, which has yielded the most abundant chondrichthyan assemblage from the Southern Hemisphere to date. Previously described representatives of Hexanchus sp., Squalus weltoni, Squalus woodburnei, Centrophorus sp., and Squatina sp. are confirmed and dental variations are documented. Although the teeth of Squatina sp. differ from other Palaeogene squatinid species, we refrain from introducing a new species. A new dalatiid taxon, Eodalatias austrinalis gen. et sp. nov. is described. This new material not only increases the diversity of Eocene Antarctic elasmobranchs but also allows assuming that favourable deep-water habitats were available in the Eocene Antarctic Ocean off Antarctica in the Eocene. The occurrences of deep-water inhabitants in shallow, near-coastal waters of the Antarctic Peninsula agrees well with extant distribution patterns.

Eocene squalomorph sharks (Chondrichthyes, Elasmobranchii) from Antarctica.

Science.gov (United States)

Engelbrecht, Andrea; Mörs, Thomas; Reguero, Marcelo A; Kriwet, Jürgen

2017-10-01

Rare remains of predominantly deep-water sharks of the families Hexanchidae, Squalidae, Dalatiidae, Centrophoridae, and Squatinidae are described from the Eocene La Meseta Formation, Seymour Island, Antarctic Peninsula, which has yielded the most abundant chondrichthyan assemblage from the Southern Hemisphere to date. Previously described representatives of Hexanchus sp., Squalus weltoni , Squalus woodburnei , Centrophorus sp., and Squatina sp. are confirmed and dental variations are documented. Although the teeth of Squatina sp. differ from other Palaeogene squatinid species, we refrain from introducing a new species. A new dalatiid taxon, Eodalatias austrinalis gen. et sp. nov. is described. This new material not only increases the diversity of Eocene Antarctic elasmobranchs but also allows assuming that favourable deep-water habitats were available in the Eocene Antarctic Ocean off Antarctica in the Eocene. The occurrences of deep-water inhabitants in shallow, near-coastal waters of the Antarctic Peninsula agrees well with extant distribution patterns.

76 FR 39905 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

Science.gov (United States)

2011-07-07

... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and... ASPA 134--Cierva Point and Offshore islands, Danco Coast, Antarctica, to install boreholes and a soil... occurrence and properties, and soil properties along a latitudinal gradient on the western Antarctic...

Continent-wide risk assessment for the establishment of nonindigenous species in Antarctica

Science.gov (United States)

Chown, Steven L.; Huiskes, Ad H. L.; Gremmen, Niek J. M.; Lee, Jennifer E.; Terauds, Aleks; Crosbie, Kim; Frenot, Yves; Hughes, Kevin A.; Imura, Satoshi; Kiefer, Kate; Lebouvier, Marc; Raymond, Ben; Tsujimoto, Megumu; Ware, Chris; Van de Vijver, Bart; Bergstrom, Dana Michelle

2012-01-01

Invasive alien species are among the primary causes of biodiversity change globally, with the risks thereof broadly understood for most regions of the world. They are similarly thought to be among the most significant conservation threats to Antarctica, especially as climate change proceeds in the region. However, no comprehensive, continent-wide evaluation of the risks to Antarctica posed by such species has been undertaken. Here we do so by sampling, identifying, and mapping the vascular plant propagules carried by all categories of visitors to Antarctica during the International Polar Year's first season (2007–2008) and assessing propagule establishment likelihood based on their identity and origins and on spatial variation in Antarctica's climate. For an evaluation of the situation in 2100, we use modeled climates based on the Intergovernmental Panel on Climate Change's Special Report on Emissions Scenarios Scenario A1B [Nakićenović N, Swart R, eds (2000) Special Report on Emissions Scenarios: A Special Report of Working Group III of the Intergovernmental Panel on Climate Change (Cambridge University Press, Cambridge, UK)]. Visitors carrying seeds average 9.5 seeds per person, although as vectors, scientists carry greater propagule loads than tourists. Annual tourist numbers (∼33,054) are higher than those of scientists (∼7,085), thus tempering these differences in propagule load. Alien species establishment is currently most likely for the Western Antarctic Peninsula. Recent founder populations of several alien species in this area corroborate these findings. With climate change, risks will grow in the Antarctic Peninsula, Ross Sea, and East Antarctic coastal regions. Our evidence-based assessment demonstrates which parts of Antarctica are at growing risk from alien species that may become invasive and provides the means to mitigate this threat now and into the future as the continent's climate changes. PMID:22393003

Mass balance of the Antarctic ice sheet.

Science.gov (United States)

Wingham, D J; Shepherd, A; Muir, A; Marshall, G J

2006-07-15

The Antarctic contribution to sea-level rise has long been uncertain. While regional variability in ice dynamics has been revealed, a picture of mass changes throughout the continental ice sheet is lacking. Here, we use satellite radar altimetry to measure the elevation change of 72% of the grounded ice sheet during the period 1992-2003. Depending on the density of the snow giving rise to the observed elevation fluctuations, the ice sheet mass trend falls in the range -5-+85Gtyr-1. We find that data from climate model reanalyses are not able to characterise the contemporary snowfall fluctuation with useful accuracy and our best estimate of the overall mass trend-growth of 27+/-29Gtyr-1-is based on an assessment of the expected snowfall variability. Mass gains from accumulating snow, particularly on the Antarctic Peninsula and within East Antarctica, exceed the ice dynamic mass loss from West Antarctica. The result exacerbates the difficulty of explaining twentieth century sea-level rise.

Modelling the Antarctic Ice Sheet

DEFF Research Database (Denmark)

Pedersen, Jens Olaf Pepke; Holm, A.

2015-01-01

to sea level high stands during past interglacial periods. A number of AIS models have been developed and applied to try to understand the workings of the AIS and to form a robust basis for future projections of the AIS contribution to sea level change. The recent DCESS (Danish Center for Earth System......The Antarctic ice sheet is a major player in the Earth’s climate system and is by far the largest depository of fresh water on the planet. Ice stored in the Antarctic ice sheet (AIS) contains enough water to raise sea level by about 58 m, and ice loss from Antarctica contributed significantly...

Hydrological Controls on Ecosystem Dynamics in Lake Fryxell, Antarctica.

Directory of Open Access Journals (Sweden)

Radu Herbei

Full Text Available The McMurdo Dry Valleys constitute the largest ice free area of Antarctica. The area is a polar desert with an annual precipitation of ∼ 3 cm water equivalent, but contains several lakes fed by glacial melt water streams that flow from four to twelve weeks of the year. Over the past ∼20 years, data have been collected on the lakes located in Taylor Valley, Antarctica as part of the McMurdo Dry Valley Long-Term Ecological Research program (MCM-LTER. This work aims to understand the impact of climate variations on the biological processes in all the ecosystem types within Taylor Valley, including the lakes. These lakes are stratified, closed-basin systems and are perennially covered with ice. Each lake contains a variety of planktonic and benthic algae that require nutrients for photosynthesis and growth. The work presented here focuses on Lake Fryxell, one of the three main lakes of Taylor Valley; it is fed by thirteen melt-water streams. We use a functional regression approach to link the physical, chemical, and biological processes within the stream-lake system to evaluate the input of water and nutrients on the biological processes in the lakes. The technique has been shown previously to provide important insights into these Antarctic lacustrine systems where data acquisition is not temporally coherent. We use data on primary production (PPR and chlorophyll-A (CHLfrom Lake Fryxell as well as discharge observations from two streams flowing into the lake. Our findings show an association between both PPR, CHL and stream input.

Environmental and climate changes in Antarctica in the Geological Past

Directory of Open Access Journals (Sweden)

G. L. Leitchenkov

2014-01-01

Full Text Available In the Cretaceous time, Antarctica was characterized by subtropical and tropical climate. The Early Eocene was warmest in the Antarctic history but this Climatic Optimum terminated with a long-term cooling trend that culminated in continental-scale glaciation of Antarctica at about 34 Ma ago. There is indirect evidence that small ice caps developed within central Antarctica in the Late Eocene (42−34 Ma. From the Early Oligocene to the Middle Miocene (34−13 Ma ice sheet was wet-based and fluctuated considerably in volume, but about 14 m.y. ago it became dry-based and more stable.  Seismic data collected on the East Antarctic margin give valuable information on dynamics of the past ice sheets. These data shows that the sedimentary cover of the western Wilkes Land margin includes a giant (c. 200 000 km2 deep-water fan which formed between c. 43 and 34 Ma ago. The average rate of sedimentation in the central part of fan was 230–250 m/m.y. Active input of terrigenous sediments into deep-water denotes high-energy fluvial system within the Wilkes Land. Emergence of this fluvial system evidences earliest glaciation in the Antarctic interior which fed full-flowing rivers. The thickness of strata deposited during post-Early Oligocene glaciations on the Antarctic margin generally reflects the averaged energy of depositional environments. The thickest sediments (up to 2.0 km, i.e. almost twice more than in other parts of East Antarctic margin and inferred highest energy are seen in the central Cooperation Sea, on the central Wilkes Land margin and in the D'Urville Sea. The areas with the thickest post-Early Oligocene strata correlate with places where present-day ice discharge is highest, such as via the Lambert, Totten and Mertz/Ninnis Glaciers. The correlation points to high ice (and sediment flux in the same areas since the Early Oligocene.

75 FR 57299 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

Science.gov (United States)

2010-09-20

... Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism and... spatial scales of various types of disturbances in and around McMurdo Station, Antarctica. The sampling...

Meteorological observatory for Antarctic data collection

International Nuclear Information System (INIS)

Grigioni, P.; De Silvestri, L.

1996-01-01

In the last years, a great number of automatic weather stations was installed in Antarctica, with the aim to examine closely the weather and climate of this region and to improve the coverage of measuring points on the Antarctic surface. In 1987 the Italian Antarctic Project started to set up a meteorological network, in an area not completely covered by other countries. Some of the activities performed by the meteorological observatory, concerning technical functions such as maintenance of the AWS's and the execution of radio soundings, or relating to scientific purposes such as validation and elaboration of collected data, are exposed. Finally, some climatological considerations on the thermal behaviour of the Antarctic troposphere such as 'coreless winter', and on the wind field, including katabatic flows in North Victoria Land are described

Geochemical markers of soil anthropogenic contaminants in polar scientific stations nearby (Antarctica, King George Island).

Science.gov (United States)

Prus, Wojciech; Fabiańska, Monika J; Łabno, Radosław

2015-06-15

The organic contamination of Antarctic soils and terrestrial sediments from nearby of five polar scientific stations on King George Island (Antarctica) was investigated. Gas chromatography-mass spectrometry (GC-MS) was applied to find composition of dichloromethane extracts of soil and terrestrial sediments. The presence of geochemical markers, such as n-alkanes, steranes, pentacyclic triterpenoids, and alkyl PAHs, their distribution types, and values of their ratios indicates the predominating source of organic fossil fuels and products of their refining rather than from the natural Antarctic environment. Fossil fuel-originated compounds well survived in conditions of Antarctic climate over long times thus enabling to characterize geochemical features of source fossil fuel identified as petroleum expelled from kerogen II of algal/bacterial origins deposited in sub-oxic conditions and being in the middle of catagenesis. Both microbial activity and water leaching play an important role in degradation of terrestrial oil spills in the Antarctica climate, and petroleum alteration occurs lowly over long periods of time. Synthetic anthropogenic compounds found in terrestrial Antarctica sediments included diisopropylnaphthalenes, products of their sulfonates degradation in paper combustion, and organophosporus compounds used as retardants and plasticizers. Copyright © 2015 Elsevier B.V. All rights reserved.

Seasonal features of black carbon measured at Syowa Station, Antarctica

Science.gov (United States)

Hara, K.; Osada, K.; Yabuki, M.; Shiobara, M.; Yamanouchi, T.

2015-12-01

Black carbon (BC) is one of important aerosol constituents because the strong light absorption ability. Low concentrations of aerosols and BC let BC make insignificant contribution to aerosol radiative forcing in the Antarctica at the moment. Because of less or negligible source strength of BC in the Antarctic circle, BC can be used as a tracer of transport from the mid-latitudes. This study aims to understand seasonal feature, transport pathway, and origins of black carbon in the Antarctic coats. Black carbon measurement has been made using 7-wavelength aethalometer at Syowa Station, Antarctica since February, 2005. Mass BC concentrations were estimated from light attenuation by Weingartner's correction procedure (Weingartner et al., 2003) in this study. Detection limit was 0.2 - 0.4 ng/m3 in our measurement conditions (2-hour resolution and flow rate of ca. 10LPM). BC concentrations ranged from near detection limit to 55.7 ng/m3 at Syowa Station, Antarctica during the measurements. No trend has been observed since February, 2005. High BC concentrations were coincident with poleward flow from the mid-latitudes under the storm conditions by cyclone approach, whereas low BC concentrations were found in transport from coastal regions and the Antarctic continent. Considering that outflow from South America and Southern Africa affect remarkably air quality in the Southern Ocean of Atlantic and Indian Ocean sectors, BC at Syowa Station might be originated from biomass burning and human activity on South America and Southern Africa. Seasonal features of BC at Syowa Station shows maximum in September - October and lower in December - April. Spring maximum in September - October was obtained at the other Antarctic stations (Neumayer, Halley, South pole, and Ferraz). Although second maximum was found in January at the other stations, the maximum was not observed at Syowa Station.

Micromorphological features of the fine earth and skeletal fractions of soils of West Antarctica in the areas of Russian Antarctic stations

Science.gov (United States)

Abakumov, E. V.; Gagarina, E. I.; Sapega, V. F.; Vlasov, D. Yu.

2013-12-01

Micromorphological features of the fine earth and skeletal fractions of soils of West Antarctica forming under different conditions of pedogenesis have been studied in the areas of Russian Antarctic stations. The processes of mineral weathering and alteration of rock fragments are more pronounced in the Subantarctic soils with better developed humification and immobilization of iron compounds under conditions of surface overmoistening. The biogenic accumulative processes in the soils of King George Island result in the appearance of initial forms of humic plasma that have not been detected in the Antarctic soils in the areas of the Russkaya and Leningradskaya stations. Humus films on mineral grains are present in the soils of King George Island, and organic plasmic material is present in the ornithogenic soils under penguin guano on Lindsey Island. High-latitude Antarctic soils may contain surface concentrations of organic matter; rock fragments are covered by iron oxides and soluble salts. The formation of amorphous organic plasma takes place in the ornithogenic soils of Lindsey Island. The microprobe analysis indicates the presence of local concentrations of organic matter and pedogenic compounds not only on the surface of rock fragments but also in the fissures inside them. This analysis has also proved the translocation of guano-derived organic substances inside rock fragments through a system of fissures in the soils of Lindsey Island and the development of a network of pores inside rock fragments in the soils of King George Island.

Tracking the El Nino events from Antarctic ice core records

International Nuclear Information System (INIS)

Keskin, S.S.; Oelmez, I.

2004-01-01

Sodium and chlorine measurements were made by instrumental neutron activation analysis (INAA) on stratigraphically dated ice core samples from Byrd Station, Antarctica, for the last three centuries. The time period between 1969 and 1989 showed an enhanced impact on the Antarctic ice sheets from oceans in the form of marine aerosols. A disturbed ocean-atmosphere interface due to El Ni Southern Oscillation (ENSO) events seems to be a candidate for this observation in Antarctica. (author)

Insignificant change in Antarctic snowmelt volume since 1979

NARCIS (Netherlands)

Kuipers Munneke, P.; Picard, G.; van den Broeke, M.R.; Lenaerts, J.T.M.; van Meijgaard, E.

2012-01-01

Surface snowmelt is widespread in coastal Antarctica. Satellite-based microwave sensors have been observing melt area and duration for over three decades. However, these observations do not reveal the total volume of meltwater produced on the ice sheet. Here we present an Antarctic melt volume

Study of the active layer at the Spanish Antarctic station “Gabriel de Castilla”, Deception Island, Antarctica

International Nuclear Information System (INIS)

Pablo, M.A. de; Molina, A.; Recio, C.; Ramos, M.; Goyanes, G.; Ropero, M.A.

2017-01-01

The degradation of permanent frozen ground (permafrost) and the increase in the thickness of the active layer may be caused both by natural processes (such as global climate change) and by anthropic activity, which changes the natural environmental conditions that allow its existence, as has been widely reported to occur in the northern polar and subpolar regions. In the case of Antarctica, some scientific research stations are located in areas with permafrost, such as the Spanish Antarctic station “Gabriel de Castilla” on Deception Island. In the place where the station is located, an important increase in erosion has been observed in recent years, including the excavation of new gullies and the erosion of the coastal cliffs. In order to develop an initial analysis of the possible effects of the station on the permafrost degradation, ground temperature has been monitored since 2012 and the thickness and of the active layer and the temperature, both inside and beneath the station, have also been sporadically measured. Here we show the results and discuss how the station reduces the freezing of the ground during the winter when the station is closed and facilitates the warming of the ground during the living periods of the station in the Antarctic summer. Those initial results and conclusions make necessary to continue the study of the permafrost and the active layer in the station site by systematic monitoring of the ground temperature and the thickness of the active layer. [es

Lichensphere: a protected natural microhabitat of the non-lichenised fungal communities living in extreme environments of Antarctica.

Science.gov (United States)

Santiago, Iara F; Soares, Marco Aurélio; Rosa, Carlos A; Rosa, Luiz H

2015-11-01

We surveyed the diversity, distribution and ecology of non-lichenised fungal communities associated with the Antarctic lichens Usnea antarctica and Usnea aurantiaco-atra across Antarctica. The phylogenetic study of the 438 fungi isolates identified 74 taxa from 21 genera of Ascomycota, Basidiomycota and Zygomycota. The most abundant taxa were Pseudogymnoascus sp., Thelebolus sp., Antarctomyces psychrotrophicus and Cryptococcus victoriae, which are considered endemic and/or highly adapted to Antarctica. Thirty-five fungi may represent new and/or endemic species. The fungal communities displayed high diversity, richness and dominance indices; however, the similarity among the communities was variable. After discovering rich and diverse fungal communities composed of symbionts, decomposers, parasites and endemic and cold-adapted cosmopolitan taxa, we introduced the term "lichensphere". We hypothesised that the lichensphere may represent a protected natural microhabitat with favourable conditions able to help non-lichenised fungi and other Antarctic life forms survive and disperse in the extreme environments of Antarctica.

Combustion of available fossil-fuel resources sufficient to eliminate the Antarctic Ice Sheet

Science.gov (United States)

Winkelmann, R.; Levermann, A.; Ridgwell, A.; Caldeira, K.

2015-12-01

The Antarctic Ice Sheet stores water equivalent to 58 meters in global sea-level rise. Here we show in simulations with the Parallel Ice Sheet Model that burning the currently attainable fossil-fuel resources is sufficient to eliminate the ice sheet. With cumulative fossil-fuel emissions of 10 000 GtC, Antarctica is projected to become almost ice-free with an average contribution to sea-level rise exceeding 3 meters per century during the first millennium. Consistent with recent observations and simulations, the West Antarctic Ice Sheet becomes unstable with 600 to 800 GtC of additional carbon emissions. Beyond this additional carbon release, the destabilization of ice basins in both West- and East Antarctica results in a threshold-increase in global sea level. Unabated carbon emissions thus threaten the Antarctic Ice Sheet in its entirety with associated sea-level rise that far exceeds that of all other possible sources.

Clinical Herpes Zoster in Antarctica as a Model for Spaceflight.

Science.gov (United States)

Reyes, David P; Brinley, Alaina A; Blue, Rebecca S; Gruschkus, Stephen K; Allen, Andrew T; Parazynski, Scott E

2017-08-01

Antarctica is a useful analog for spaceflight, as both environments are remote, isolated, and with limited resources. While previous studies have demonstrated increased asymptomatic viral shedding in both the Antarctic and spaceflight environments, clinical manifestations of reactivated viral disease have been less frequently identified. We sought to identify the incidence of clinical herpes zoster from viral reactivation in the Antarctic winter-over population. Medical records from the 2014 winter season were reviewed for the incidence of zoster in U.S. Antarctic personnel and then compared to the age-matched U.S. Five cases of clinical herpes zoster occurred in the Antarctic Station population of 204 persons, for an incidence of 33.3 per 1000 person-years vs. 3.2 per 1000 person-years in the general population. Four cases were in persons under age 40, yielding an incidence of 106.7 per 1000 person-years in persons ages 30-39 compared to an incidence of 2.0 per 1000 person-years in the same U.S. age group. Immune suppression due to the stressful Antarctic environment may have contributed to the increased incidence of herpes zoster in U.S. Antarctic personnel during the winter of 2014. Working and living in isolated, confined, and extreme environments can cause immune suppression, reactivating latent viruses and increasing viral shedding and symptomatic disease. Such changes have been observed in other austere environments, including spaceflight, suggesting that clinical manifestations of viral reactivation may be seen in future spaceflight.Reyes DP, Brinley AA, Blue RS, Gruschkus SK, Allen AT, Parazynski SE. Clinical herpes zoster in Antarctica as a model for spaceflight. Aerosp Med Hum Perform. 2017; 88(8):784-788.

Unveiling the Antarctic subglacial landscape.

Science.gov (United States)

Warner, Roland; Roberts, Jason

2010-05-01

Better knowledge of the subglacial landscape of Antarctica is vital to reducing uncertainties regarding prediction of the evolution of the ice sheet. These uncertainties are associated with bedrock geometry for ice sheet dynamics, including possible marine ice sheet instabilities and subglacial hydrological pathways (e.g. Wright et al., 2008). Major collaborative aerogeophysics surveys motivated by the International Polar Year (e.g. ICECAP and AGAP), and continuing large scale radar echo sounding campaigns (ICECAP and NASA Ice Bridge) are significantly improving the coverage. However, the vast size of Antarctica and logistic difficulties mean that data gaps persist, and ice thickness data remains spatially inhomogeneous. The physics governing large scale ice sheet flow enables ice thickness, and hence bedrock topography, to be inferred from knowledge of ice sheet surface topography and considerations of ice sheet mass balance, even in areas with sparse ice thickness measurements (Warner and Budd, 2000). We have developed a robust physically motivated interpolation scheme, based on these methods, and used it to generate a comprehensive map of Antarctic bedrock topography, using along-track ice thickness data assembled for the BEDMAP project (Lythe et al., 2001). This approach reduces ice thickness biases, compared to traditional inverse distance interpolation schemes which ignore the information available from considerations of ice sheet flow. In addition, the use of improved balance fluxes, calculated using a Lagrangian scheme, eliminates the grid orientation biases in ice fluxes associated with finite difference methods (Budd and Warner, 1996, Le Brocq et al., 2006). The present map was generated using a recent surface DEM (Bamber et al., 2009, Griggs and Bamber, 2009) and accumulation distribution (van de Berg et al., 2006). Comparing our results with recent high resolution regional surveys gives confidence that all major subglacial topographic features are

76 FR 52354 - Notice of Permit Application Received Under the Antarctic Conservation Act of 1978

Science.gov (United States)

2011-08-22

... can be broken and release plastic into the ocean. (2) Fishing nets: (a) Plankton nets come in a... in ASPA 149-Cape Shirreff, Livingston Island by the Antarctic Marine Living Resources (AMLR) Program... release of a designated pollutant in Antarctica, and for the release of waste in Antarctica. NSF has...

Physical properties of aerosols at Maitri, Antarctica

Indian Academy of Sciences (India)

Measurements of the submicron aerosol size distribution made at the Indian Antarctic station, Maitri (70° 45′S, 11° 44′E) from January 10th to February 24th, 1997, are reported. Total aerosol concentrations normally range from 800 to 1200 particles cm-3 which are typical values for the coastal stations at Antarctica in ...

Towards a tipping point? Exploring the capacity to self-regulate Antarctic tourism using agent-based modelling

NARCIS (Netherlands)

Student, J.R.; Amelung, B.; Lamers, M.A.J.

2016-01-01

Antarctica attracts tourists who want to explore its unique nature and landscapes. Antarctic tourism has rapidly grown since 1991 and is currently picking up again after the recent global economic downturn. Tourism activities are subject to the rules of the Antarctic Treaty System (ATS) and the

Human Activity and Pollution in Antarctica

Science.gov (United States)

Graf, H.-F.; Shirsat, S. V.; Podzun, R.

2009-04-01

A regional climate chemistry model is used to determine the level of pollution of the Antarctic continent due to anthropogenic and natural emission of sulphur species. Based on an emission inventory for the year 2004/2005 including emissions from energy use and ground traffic at and between Antarctic research stations, flight activity, tourist and scientific ship operations, and emissions from the Mt. Erebus volcano, atmospheric concentration and deposition rates of sulphur species and black carbon were simulated at 0.5 degree resolution for the whole Antarctic continent. The biggest anthropogenic source of pollution is ship operations. These concentrate near the Antarctic Peninsula and close to the big scientific stations at Queen Maud Land and in the Ross sea area. The prevailing winds guarantee that most of the anthropogenic emissions from sources near the coast will be blown to lower latitudes and do not affect the continent. While atmospheric concentrations over vast areas remain extremely low, in some places locally concentrations and deposition rates are reached that may be detectable by in-situ measurements and give rise to concern. Especially at the Peninsula atmospheric concentrations and surface deposition of sulphur and soot are dominated by ship emissions. The largest part of shipping activity in this region is from tourist ships, a strongly increasing business. The by far biggest source of sulphur species in Antarctica is the Mt. Erebus volcano. It is also the only source that remains equally strong in polar winter. However, due to its high altitude and the long life time of SO2, especially in winter resulting in long range transport and dilution, Erebus emissions contribute relatively little to deposition of sulphur in the most anthropogenic polluted areas while they dominate the sulphur deposition in central Antarctica.

Photosynthesis in a sub-Antarctic shore-zone lichen

NARCIS (Netherlands)

Smith, V.; Gremmen, N.J.M.

2001-01-01

Photosynthetic responses to moisture, light, temperature, salinity and inorganic nitrogen fertilization are reported for a shore-zone lichen Turgidiusculum complicatulum (formerly Mastodia tesselata), a possible recent introduction to sub-Antarctic Marion Island. Optimum moisture contents for net

The use of drilling by the U.S. Antarctic program

Energy Technology Data Exchange (ETDEWEB)

Wade, M.C.; Webb, J.W.; Hedberg, W.H.

1994-08-01

This report on drilling in the Antarctic has been prepared by the U.S. National Science Foundation (NSF) to assist principal investigators and others in complying with the National Environmental Policy Act (NEPA) and the Antarctic Treaty of 1961. Implementing regulations for NEPA are spelled out in 40 CFR 1500-1508. Environmental protection under the Antarctic Treaty is addressed in the Protocol on Environmental Protection to the Antarctic Treaty (hereafter referred to as the Protocol), which was adopted by 26 countries in 1991. In the United States, responsibility for compliance with these requirements rests with the NSF Office of Polar Programs (OPP), which manages the U.S. Antarctic Program (USAP). The USAP recognizes the potentially profound impacts that its presence and activities can have on the antarctic environment. In its extensive support of operations and research in Antarctica, the USAP uses all practical means to foster and maintain natural conditions while supporting scientific endeavors in a safe and healthful manner. Reducing human impacts on the antarctic environment is a major goal of the USAP. The USAP`s operating philosophy is based on broad yet reasonable and practical assumptions concerning environmental protection. The USAP maintains three year-round stations on the continent to support scientific research. Research and associated support operations at these stations and camps sometimes involve drilling into ice, soil, or ocean sediments. In order to comply with NEPA and the Protocol, it is necessary for principal investigators and others to assess the environmental effects of drilling. This report has been prepared to assist in this process by describing various drilling technologies currently available for use in Antarctica, generally characterizing the potential environmental impacts associated with these drilling techniques, and identifying possible mitigation measures to reduce impacts.

Combustion of available fossil fuel resources sufficient to eliminate the Antarctic Ice Sheet.

Science.gov (United States)

Winkelmann, Ricarda; Levermann, Anders; Ridgwell, Andy; Caldeira, Ken

2015-09-01

The Antarctic Ice Sheet stores water equivalent to 58 m in global sea-level rise. We show in simulations using the Parallel Ice Sheet Model that burning the currently attainable fossil fuel resources is sufficient to eliminate the ice sheet. With cumulative fossil fuel emissions of 10,000 gigatonnes of carbon (GtC), Antarctica is projected to become almost ice-free with an average contribution to sea-level rise exceeding 3 m per century during the first millennium. Consistent with recent observations and simulations, the West Antarctic Ice Sheet becomes unstable with 600 to 800 GtC of additional carbon emissions. Beyond this additional carbon release, the destabilization of ice basins in both West and East Antarctica results in a threshold increase in global sea level. Unabated carbon emissions thus threaten the Antarctic Ice Sheet in its entirety with associated sea-level rise that far exceeds that of all other possible sources.

Yeast activities involved in carbon and nitrogen cycles in Antarctica

Science.gov (United States)

Antarctica and sub Antarctic regions are characterized by extreme conditions for life such as low temperatures and nutrient availability, high solar radiation and dryness, however, microorganisms from the three domains of life have been found as common inhabitants of soils and waters from those zone...

Antarctica: Arena for South American Cooperation or Conflict.

Science.gov (United States)

Child, Jack

A number of converging circumstances suggest that Antarctica may be a major object of geopolitical attention in South America in the decade to come. The Malvinas/Falklands crisis focused geopolitical attention on the South Atlantic and the chain of Southern (Austral) Islands which link the southern tip of South America to the Antarctic Peninsula.…

Protection of the wilderness and aesthetic values of Antarctica: Geographical Information Systems (GIS) as a tool

Science.gov (United States)

Rupert Summerson; Tina Tin

2011-01-01

Antarctica is designated by the Antarctic Treaty System as a "natural reserve devoted to peace and science" (http://www.ats.aq/index_e.htm). Multiple, and sometimes conflicting, values are protected. In a place where wilderness protection and certain forms of human activity are both prized, a discussion of the protection of the Antarctic wilderness...

Coastal-Change and Glaciological Map of the Palmer Land Area, Antarctica: 1947-2009

Science.gov (United States)

Ferrigno, Jane G.; Cook, Alison J.; Mathie, Amy M.; Williams, Richard S.; Swithinbank, Charles; Foley, Kevin M.; Fox, Adrian J.; Thomson, Janet W.; Sievers, Jorn

2009-01-01

Reduction in the area and volume of the two polar ice sheets is intricately linked to changes in global climate, and the resulting rise in sea level could severely impact the densely populated coastal regions on Earth. Antarctica is Earth's largest reservoir of glacial ice. Melting of the West Antarctic part alone of the Antarctic ice sheet would cause a sea-level rise of approximately 6 meters (m), and the potential sea-level rise after melting of the entire Antarctic ice sheet is estimated to be 65 m (Lythe and others, 2001) to 73 m (Williams and Hall, 1993). The mass balance (the net volumetric gain or loss) of the Antarctic ice sheet is highly complex, responding differently to different climatic and other conditions in each region (Vaughan, 2005). In a review paper, Rignot and Thomas (2002) concluded that the West Antarctic ice sheet is probably becoming thinner overall; although it is known to be thickening in the west, it is thinning in the north. The mass balance of the East Antarctic ice sheet is thought by Davis and others (2005) to be positive on the basis of the change in satellite-altimetry measurements made between 1992 and 2003. Measurement of changes in area and mass balance of the Antarctic ice sheet was given a very high priority in recommendations by the Polar Research Board of the National Research Council (1986), in subsequent recommendations by the Scientific Committee on Antarctic Research (SCAR) (1989, 1993), and by the National Science Foundation's (1990) Division of Polar Programs. On the basis of these recommendations, the U.S. Geological Survey (USGS) decided that the archive of early 1970s Landsat 1, 2, and 3 Multispectral Scanner (MSS) images of Antarctica and the subsequent repeat coverage made possible with Landsat and other satellite images provided an excellent means of documenting changes in the cryospheric coastline of Antarctica (Ferrigno and Gould, 1987). The availability of this information provided the impetus for carrying

Soils of Sub-Antarctic tundras: diversity and basic chemical characteristics

Science.gov (United States)

Abakumov, Evgeny; Vlasov, Dmitry; Mukhametova, Nadezhda

2014-05-01

Antarctic peninsula is known as specific part of Antarctica, which is characterizes by humid and relatively warm climate of so-called sub Antarctic (maritime) zone. Annual precipitation and long above zero period provides the possibility of sustainable tundra's ecosystem formation. Therefore, the soil diversity of these tundra landscapes is maximal in the whole Antarctic. Moreover, the thickness of parent material debris's is also highest and achieves a 1 or 2 meters as highest. The presence of higher vascular plants Deshampsia antarctica which is considered as one of the main edificators provides the development of humus accumulation in upper solum. Penguins activity provides an intensive soil fertilization and development of plant communities with increased density. All these factors leads to formation of specific and quite diverse soil cover in sub Antarctic tundra's. These ecosystems are presented by following permafrost affected soils: Leptosols, Lithoosols, Crysols, Gleysols, Peats and Ornhitosols. Also the post Ornhitosols are widely spreaded in subantarcic ecosystems, they forms on the penguin rockeries during the plant succession development, leaching of nutrients and organic matter mineralization. "Amphibious" soils are specific for seasonal lakes, which evaporates in the end if Australian summer. These soils have specific features of bio sediments and soils as well. Soil chemical characteristic as well as organic matter features discussed in comparison with Antacrtic continental soil in presentation.

Microbial ecology of terrestrial Antarctica: Are microbial systems at risk from human activities?

Energy Technology Data Exchange (ETDEWEB)

White, G.J.

1996-08-01

Many of the ecological systems found in continental Antarctica are comprised entirely of microbial species. Concerns have arisen that these microbial systems might be at risk either directly through the actions of humans or indirectly through increased competition from introduced species. Although protection of native biota is covered by the Protocol on Environmental Protection to the Antarctic Treaty, strict measures for preventing the introduction on non-native species or for protecting microbial habitats may be impractical. This report summarizes the research conducted to date on microbial ecosystems in continental Antarctica and discusses the need for protecting these ecosystems. The focus is on communities inhabiting soil and rock surfaces in non-coastal areas of continental Antarctica. Although current polices regarding waste management and other operations in Antarctic research stations serve to reduce the introduction on non- native microbial species, importation cannot be eliminated entirely. Increased awareness of microbial habitats by field personnel and protection of certain unique habitats from physical destruction by humans may be necessary. At present, small-scale impacts from human activities are occurring in certain areas both in terms of introduced species and destruction of habitat. On a large scale, however, it is questionable whether the introduction of non-native microbial species to terrestrial Antarctica merits concern.

High Resolution Spatial Mapping of Human Footprint across Antarctica and Its Implications for the Strategic Conservation of Avifauna

OpenAIRE

Peter, Hans-Ulrich; Pertierra, Luis R.; Hughes, Kevin A.; Vega, Greta C.; Olalla-Tárraga, Miguel Á.

2017-01-01

Human footprint models allow visualization of human spatial pressure across the globe. Up until now, Antarctica has been omitted from global footprint models, due possibly to the lack of a permanent human population and poor accessibility to necessary datasets. Yet Antarctic ecosystems face increasing cumulative impacts from the expanding tourism industry and national Antarctic operator activities, the management of which could be improved with footprint assessment tools. Moreover, Antarctic ...

Bacterial succession in Antarctic soils of two glacier forefields on Larsemann Hills, East Antarctica.

Science.gov (United States)

Bajerski, Felizitas; Wagner, Dirk

2013-07-01

Antarctic glacier forefields are extreme environments and pioneer sites for ecological succession. Increasing temperatures due to global warming lead to enhanced deglaciation processes in cold-affected habitats, and new terrain is becoming exposed to soil formation and microbial colonization. However, only little is known about the impact of environmental changes on microbial communities and how they develop in connection to shifting habitat characteristics. In this study, using a combination of molecular and geochemical analysis, we determine the structure and development of bacterial communities depending on soil parameters in two different glacier forefields on Larsemann Hills, East Antarctica. Our results demonstrate that deglaciation-dependent habitat formation, resulting in a gradient in soil moisture, pH and conductivity, leads to an orderly bacterial succession for some groups, for example Cyanobacteria, Bacteroidetes and Deltaproteobacteria in a transect representing 'classical' glacier forefields. A variable bacterial distribution and different composed communities were revealed according to soil heterogeneity in a slightly 'matured' glacier forefield transect, where Gemmatimonadetes, Flavobacteria, Gamma- and Deltaproteobacteria occur depending on water availability and soil depth. Actinobacteria are dominant in both sites with dominance connected to certain trace elements in the glacier forefields. © 2013 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Tourism in Antarctica : Increasing Diversity and the Legal Criteria for Authorisation

NARCIS (Netherlands)

Bastmeijer, C.J.

2003-01-01

Both the intensity and the diversity of tourist activities in Antarctica are increasing. Activities conducted in the Antarctic today include ski-expeditions, mountain climbing, marathons, long-distance swimming and scuba diving. In this article the question is discussed whether the Protocol on

Vigorous lateral export of the meltwater outflow from beneath an Antarctic ice shelf.

Science.gov (United States)

Garabato, Alberto C Naveira; Forryan, Alexander; Dutrieux, Pierre; Brannigan, Liam; Biddle, Louise C; Heywood, Karen J; Jenkins, Adrian; Firing, Yvonne L; Kimura, Satoshi

2017-02-09

The instability and accelerated melting of the Antarctic Ice Sheet are among the foremost elements of contemporary global climate change. The increased freshwater output from Antarctica is important in determining sea level rise, the fate of Antarctic sea ice and its effect on the Earth's albedo, ongoing changes in global deep-ocean ventilation, and the evolution of Southern Ocean ecosystems and carbon cycling. A key uncertainty in assessing and predicting the impacts of Antarctic Ice Sheet melting concerns the vertical distribution of the exported meltwater. This is usually represented by climate-scale models as a near-surface freshwater input to the ocean, yet measurements around Antarctica reveal the meltwater to be concentrated at deeper levels. Here we use observations of the turbulent properties of the meltwater outflows from beneath a rapidly melting Antarctic ice shelf to identify the mechanism responsible for the depth of the meltwater. We show that the initial ascent of the meltwater outflow from the ice shelf cavity triggers a centrifugal overturning instability that grows by extracting kinetic energy from the lateral shear of the background oceanic flow. The instability promotes vigorous lateral export, rapid dilution by turbulent mixing, and finally settling of meltwater at depth. We use an idealized ocean circulation model to show that this mechanism is relevant to a broad spectrum of Antarctic ice shelves. Our findings demonstrate that the mechanism producing meltwater at depth is a dynamically robust feature of Antarctic melting that should be incorporated into climate-scale models.

Antarctic and Southern Ocean influences on Late Pliocene global cooling

NARCIS (Netherlands)

McKay, R.; Naish, T.; Carter, L.; Riesselman, C.; Dunbar, R.; Sjunneskog, C.; Winter, D.; Sangiorgi, F.; Warren, C.; Pagani, M.; Schouten, S.; Willmott, V.; Levy, R.; DeConto , R.M.; Powell, R.D.

2012-01-01

The influence of Antarctica and the Southern Ocean on Late Pliocene global climate reconstructions has remained ambiguous due to a lack of well-dated Antarctic-proximal, paleoenvironmental records. Here we present ice sheet, sea-surface temperature, and sea ice reconstructions from the ANDRILL

Emplacement of Antarctic ice sheet mass affects circumpolar ocean flow

NARCIS (Netherlands)

Rugenstein, Maria; Stocchi, Paolo; von der Heydt, Anna; Dijkstra, Hendrik; Brinkhuis, Henk

2014-01-01

During the Cenozoic the Antarctic continent experienced large fluctuations in ice-sheet volume. We investigate the effects of Glacial Isostatic Adjustment (GIA) on Southern Ocean circulation for the first continental scale glaciation of Antarctica (~34 Myr) by combining solid Earth and ocean dynamic

Emplacement of Antarctic ice sheet mass affects circumpolar ocean flow

NARCIS (Netherlands)

Rugenstein, M.; Stocchi, P.; van der Heydt, A.; Brinkhuis, H.

2014-01-01

During the Cenozoic the Antarctic continent experienced large fluctuations in ice-sheet volume. We investigate the effects of Glacial Isostatic Adjustment (GIA) on Southern Ocean circulation for the first continental scale glaciation of Antarctica (~ 34 Myr) by combining solid Earth and ocean

Constitutive expression of DaCBF7, an Antarctic vascular plant Deschampsia antarctica CBF homolog, resulted in improved cold tolerance in transgenic rice plants.

Science.gov (United States)

Byun, Mi Young; Lee, Jungeun; Cui, Li Hua; Kang, Yoonjee; Oh, Tae Kyung; Park, Hyun; Lee, Hyoungseok; Kim, Woo Taek

2015-07-01

Deschampsia antarctica is an Antarctic hairgrass that grows on the west coast of the Antarctic peninsula. In this report, we have identified and characterized a transcription factor, D. antarctica C-repeat binding factor 7 (DaCBF7), that is a member of the monocot group V CBF homologs. The protein contains a single AP2 domain, a putative nuclear localization signal, and the typical CBF signature. DaCBF7, like other monocot group V homologs, contains a distinct polypeptide stretch composed of 43 amino acids in front of the AP2 motif. DaCBF7 was predominantly localized to nuclei and interacted with the C-repeat/dehydration responsive element (CRT/DRE) core sequence (ACCGAC) in vitro. DaCBF7 was induced by abiotic stresses, including drought, cold, and salinity. To investigate its possible cellular role in cold tolerance, a transgenic rice system was employed. DaCBF7-overexpressing transgenic rice plants (Ubi:DaCBF7) exhibited markedly increased tolerance to cold stress compared to wild-type plants without growth defects; however, overexpression of DaCBF7 exerted little effect on tolerance to drought or salt stress. Transcriptome analysis of a Ubi:DaCBF7 transgenic line revealed 13 genes that were up-regulated in DaCBF7-overexpressing plants compared to wild-type plants in the absence of cold stress and in short- or long-term cold stress. Five of these genes, dehydrin, remorin, Os03g63870, Os11g34790, and Os10g22630, contained putative CRT/DRE or low-temperature responsive elements in their promoter regions. These results suggest that overexpression of DaCBF7 directly and indirectly induces diverse genes in transgenic rice plants and confers enhanced tolerance to cold stress. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Antarctica and Global Environmental Change - Lessons from the Past Inform Climate Change Policy Today

Science.gov (United States)

Dunbar, R. B.; Scientific Team Of Odp Drilling Leg 318; Andrill Science Team

2011-12-01

Antarctic's continental ice, sea ice, and the broader Southern Ocean form a coupled and complex climate system that interacts in important yet poorly understood ways with the low and mid-latitudes. Because of its unusual sovereignty status and the fact that there is no indigenous human population, information about climate change in Antarctica penetrates the policy world less readily than findings from other regions. Yet, Antarctica's potential to impact climate change globally is disproportionately large. Vulnerable portions of the ice sheet may contribute up to 3 to 5 meters of sea level rise in the coming centuries, including significant amounts within the next 50 years. Loss of sea ice and other changes in the Southern Ocean may reduce oceanic uptake of excess atmospheric carbon dioxide, exacerbating global warming worldwide. Antarctica's impact on the Southern Hemisphere wind field is now well-established, contributing to ongoing decadal-scale perturbations in continental precipitation as well as major reorganizations of Southern Ocean food chains. Recent scientific drilling programs in the Ross Sea and off Wilkes Land, Antarctica, provide valuable insights into past climatic and biogeochemical change in Antarctica, insights of great relevance to international and national climate change policy. In this paper, we discuss polar amplification, sea level variability coupled to Antarctic ice volume, and response timescales as seen through the lens of past climate change. One key result emerging from multiple drilling programs is recognition of unanticipated dynamism in the Antarctic ice sheet during portions of the Pliocene (at a time with pCO2 levels equivalent to those anticipated late this century) as well as during "super-interglacials" of the Pleistocene. Evidence for substantially warmer ocean temperatures and reduced sea ice cover at these times suggests that polar amplification of natural climate variability, even under scenarios of relative small amounts

The late Cainozoic East Antarctic ice sheet

International Nuclear Information System (INIS)

Colhoun, E.A.

1999-01-01

A review, mainly of East Antarctic late Cainozoic (post 40 Ma) geological and geomorphological evidence, supports the hypothesis of the continuous presence of an ice sheet, of about the present size, since the late Miocene. Evidence is presented and the view advanced that, during the late Wisconsin maximum of isotope stage 2, ice was not nearly as thick or extensive over the continental shelf as required by the model of 'maximum' Antarctic glaciation. Some of the factors influencing the contribution of Antarctica to post-glacial sea-level rise are discussed. It is considered that Antarctica's contribution was probably considerably less than previously estimated. The dating of marine and freshwater sequences in the Vestfold and Bunger Hills is consistent with deglaciation around the Pleistocene Holocene boundary, after the Late Wisconsin maximum. A date of ∼25 ka BP from permafrost in the Larsemann Hills means that either the Larsemann Hills were not glaciated during the Late Wisconsin or the ice failed to erode much of the permafrost surface. The degree of weathering of rock and glacial drifts in the Vestfold, Larsemann and Bunger Hills suggests a long time for formation, perhaps considerably longer than indicated by the dated marine and freshwater sediment sequences. Cosmogenic isotope dating in the Vestfold Hills has provided equivocal ages for deglaciation. While the results could indicate deglaciation before 80 ka BP, they do not confirm such early deglaciation. If the ice cover was thin and failed to remove the previous rock exposure profile, then the assays could predate the last ice advance. Weathered iron crust fragments in the till suggest little erosion. The raised beaches of the oases are Holocene. Assuming they have been produced by post Late Wisconsin isostatic uplift and by the Holocene transgression, calculations show that the Antarctic continental ice sheet could not have been more than ∼500 m thicker in the inner shelf-coastal zone. The

Antarctic Lithosphere Studies: Progress, Problems and Promise

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Dalziel, I. W. D.; Wilson, T. J.

2017-12-01

In the sixty years since the International Geophysical Year, studies of the Antarctic lithosphere have progressed from basic geological observations and sparse geophysical measurements to continental-scale datasets of radiometric dates, ice thickness, bedrock topography and characteristics, seismic imaging and potential fields. These have been augmented by data from increasingly dense broadband seismic and geodetic networks. The Antarctic lithosphere is known to have been an integral part, indeed a "keystone" of the Pangea ( 250-185Ma) and Gondwanaland ( 540-180 Ma) supercontinents. It is widely believed to have been part of hypothetical earlier supercontinents Rodinia ( 1.0-0.75 Ga) and Columbia (Nuna) ( 2.0-1.5 Ga). Despite the paucity of exposure in East Antarctica, the new potential field datasets have emboldened workers to extrapolate Precambrian geological provinces and structures from neighboring continents into Antarctica. Hence models of the configuration of Columbia and its evolution into Rodinia and Gondwana have been proposed, and rift-flank uplift superimposed on a Proterozoic orogenic root has been hypothesized to explain the Gamburtsev Subglacial Mountains. Mesozoic-Cenozoic rifting has imparted a strong imprint on the West Antarctic lithosphere. Seismic tomographic evidence reveals lateral variation in lithospheric thickness, with the thinnest zones within the West Antarctic rift system and underlying the Amundsen Sea Embayment. Upper mantle low velocity zones are extensive, with a deeper mantle velocity anomaly underlying Marie Byrd Land marking a possible mantle plume. Misfits between crustal motions measured by GPS and GIA model predictions can, in part, be linked with the changes in lithosphere thickness and mantle rheology. Unusually high uplift rates measured by GPS in the Amundsen region can be interpreted as the response of regions with thin lithosphere and weak mantle to late Holocene ice mass loss. Horizontal displacements across the TAM

Characterising East Antarctic Lithosphere and its Rift Systems using Gravity Inversion

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Vaughan, Alan P. M.; Kusznir, Nick J.; Ferraccioli, Fausto; Leat, Phil T.; Jordan, Tom A. R. M.; Purucker, Michael E.; Golynsky, A. V. Sasha; Rogozhina, Irina

2013-04-01

Since the International Geophysical Year (1957), a view has prevailed that East Antarctica has a relatively homogeneous lithospheric structure, consisting of a craton-like mosaic of Precambrian terranes, stable since the Pan-African orogeny ~500 million years ago (e.g. Ferracioli et al. 2011). Recent recognition of a continental-scale rift system cutting the East Antarctic interior has crystallised an alternative view of much more recent geological activity with important implications. The newly defined East Antarctic Rift System (EARS) (Ferraccioli et al. 2011) appears to extend from at least the South Pole to the continental margin at the Lambert Rift, a distance of 2500 km. This is comparable in scale to the well-studied East African rift system. New analysis of RadarSat data by Golynsky & Golynsky (2009) indicates that further rift zones may form widely distributed extension zones within the continent. A pilot study (Vaughan et al. 2012), using a newly developed gravity inversion technique (Chappell & Kusznir 2008) with existing public domain satellite data, shows distinct crustal thickness provinces with overall high average thickness separated by thinner, possibly rifted, crust. Understanding the nature of crustal thickness in East Antarctica is critical because: 1) this is poorly known along the ocean-continent transition, but is necessary to improve the plate reconstruction fit between Antarctica, Australia and India in Gondwana, which will also better define how and when these continents separated; 2) lateral variation in crustal thickness can be used to test supercontinent reconstructions and assess the effects of crystalline basement architecture and mechanical properties on rifting; 3) rift zone trajectories through East Antarctica will define the geometry of zones of crustal and lithospheric thinning at plate-scale; 4) it is not clear why or when the crust of East Antarctica became so thick and elevated, but knowing this can be used to test models of

Changes in ice dynamics and mass balance of the Antarctic ice sheet.

Science.gov (United States)

Rignot, Eric

2006-07-15

The concept that the Antarctic ice sheet changes with eternal slowness has been challenged by recent observations from satellites. Pronounced regional warming in the Antarctic Peninsula triggered ice shelf collapse, which led to a 10-fold increase in glacier flow and rapid ice sheet retreat. This chain of events illustrated the vulnerability of ice shelves to climate warming and their buffering role on the mass balance of Antarctica. In West Antarctica, the Pine Island Bay sector is draining far more ice into the ocean than is stored upstream from snow accumulation. This sector could raise sea level by 1m and trigger widespread retreat of ice in West Antarctica. Pine Island Glacier accelerated 38% since 1975, and most of the speed up took place over the last decade. Its neighbour Thwaites Glacier is widening up and may double its width when its weakened eastern ice shelf breaks up. Widespread acceleration in this sector may be caused by glacier ungrounding from ice shelf melting by an ocean that has recently warmed by 0.3 degrees C. In contrast, glaciers buffered from oceanic change by large ice shelves have only small contributions to sea level. In East Antarctica, many glaciers are close to a state of mass balance, but sectors grounded well below sea level, such as Cook Ice Shelf, Ninnis/Mertz, Frost and Totten glaciers, are thinning and losing mass. Hence, East Antarctica is not immune to changes.

Can Antarctic lichens acclimatize to changes in temperature?

Science.gov (United States)

Colesie, Claudia; Büdel, Burkhard; Hurry, Vaughan; Green, Thomas George Allan

2018-03-01

The Antarctic Peninsula, a tundra biome dominated by lichens and bryophytes, is an ecozone undergoing rapid temperature shifts. Such changes may demand a high physiological plasticity of the local lichen species to maintain their role as key drivers in this pristine habitat. This study examines the response of net photosynthesis and respiration to increasing temperatures for three Antarctic lichen species with different ecological response amplitudes. We hypothesize that negative effects caused by increased temperatures can be mitigated by thermal acclimation of respiration and/or photosynthesis. The fully controlled growth chamber experiment simulated intermediate and extreme temperature increases over the time course of 6 weeks. Results showed that, in contrast to our hypothesis, none of the species was able to down-regulate temperature-driven respiratory losses through thermal acclimation of respiration. Instead, severe effects on photobiont vitality demonstrated that temperatures around 15°C mark the upper limit for the two species restricted to the Antarctic, and when mycobiont demands exceeded the photobiont capacity they could not survive within the lichen thallus. In contrast, the widespread lichen species was able to recover its homoeostasis by rapidly increasing net photosynthesis. We conclude that to understand the complete lichen response, acclimation processes of both symbionts, the photo- and the mycobiont, have to be evaluated separately. As a result, we postulate that any acclimation processes in lichen are species-specific. This, together with the high degree of response variability and sensitivity to temperature in different species that co-occur spatially close, complicates any predictions regarding future community composition in the Antarctic. Nevertheless, our results suggest that species with a broad ecological amplitude may be favoured with on-going changes in temperature. © 2017 John Wiley & Sons Ltd.

Full Waveform Adjoint Seismic Tomography of the Antarctic Plate

Science.gov (United States)

Lloyd, A. J.; Wiens, D.; Zhu, H.; Tromp, J.; Nyblade, A.; Anandakrishnan, S.; Aster, R. C.; Huerta, A. D.; Winberry, J. P.; Wilson, T. J.; Dalziel, I. W. D.; Hansen, S. E.; Shore, P.

2017-12-01

Recent studies investigating the response and influence of the solid Earth on the evolution of the cryosphere demonstrate the need to account for 3D rheological structure to better predict ice sheet dynamics, stability, and future sea level impact, as well as to improve glacial isostatic adjustment models and more accurately measure ice mass loss. Critical rheological properties like mantle viscosity and lithospheric thickness may be estimated from shear wave velocity models that, for Antarctica, would ideally possess regional-scale resolution extending down to at least the base of the transition zone (i.e. 670 km depth). However, current global- and continental-scale seismic velocity models are unable to obtain both the resolution and spatial coverage necessary, do not take advantage of the full set of available Antarctic data, and, in most instance, employ traditional seismic imaging techniques that utilize limited seismogram information. We utilize 3-component earthquake waveforms from almost 300 Antarctic broadband seismic stations and 26 southern mid-latitude stations from 270 earthquakes (5.5 ≤ Mw ≤ 7.0) between 2001-2003 and 2007-2016 to conduct a full-waveform adjoint inversion for Antarctica and surrounding regions of the Antarctic plate. Necessary forward and adjoint wavefield simulations are performed utilizing SPECFEM3D_GLOBE with the aid of the Texas Advanced Computing Center. We utilize phase observations from seismogram segments containing P, S, Rayleigh, and Love waves, including reflections and overtones, which are autonomously identified using FLEXWIN. The FLEXWIN analysis is carried out over a short (15-50 s) and long (initially 50-150 s) period band that target body waves, or body and surface waves, respectively. As our model is iteratively refined, the short-period corner of the long period band is gradually reduced to 25 s as the model converges over 20 linearized inversion iterations. We will briefly present this new high

Satellite gravity gradient views help reveal the Antarctic lithosphere

Science.gov (United States)

Ferraccioli, F.; Ebbing, J.; Pappa, F.; Kern, M.; Forsberg, R.

2017-12-01

Here we present and analyse satellite gravity gradient signatures derived from GOCE and superimpose these on tectonic and bedrock topography elements, as well as seismically-derived estimates of crustal thickness for the Antarctic continent. The GIU satellite gravity component images the contrast between the thinner crust and lithosphere underlying the West Antarctic Rift System and the Weddell Sea Rift System and the thicker lithosphere of East Antarctica. The new images also suggest that more distributed wide-mode lithospheric and crustal extension affects both the Ross Sea Embayment and the less well known Ross Ice Shelf segment of the rift system. However, this pattern is less clear towards the Bellingshousen Embayment, indicating that the rift system narrows towards the southern edge of the Antarctic Peninsula. In East Antarctica, the satellite gravity data provides new views into the Archean to Mesoproterozoic Terre Adelie Craton, and clearly shows the contrast wrt to the crust and lithosphere underlying both the Wilkes Subglacial Basin to the east and the Sabrina Subglacial Basin to the west. This finding augments recent interpretations of aeromagnetic and airborne gravity data over the region, suggesting that the Mawson Continent is a composite lithospheric-scale entity, which was affected by several Paleoproterozoic and Mesoproterozoic orogenic events. Thick crust is imaged beneath the Transantarctic Mountains, the Terre Adelie Craton, the Gamburtsev Subglacial Mountains and also Eastern Dronning Maud Land, in particular beneath the recently proposed region of the Tonian Oceanic Arc Superterrane. The GIA and GIU components help delineate the edges of several of these lithospheric provinces. One of the most prominent lithospheric-scale features discovered in East Antarctica from satellite gravity gradient imaging is the Trans East Antarctic Shear Zone that separates the Gamburtsev Province from the Eastern Dronning Maud Land Province and appears to form the

Antarctica Meta-Analysis: Psychosocial Factors Related to Long Duration Isolation and Confinement

Science.gov (United States)

Leveton, Lauren; Shea, Camille; Slack, Kelley J.; Keeton, Kathryn E.; Palinkas, Lawrence A.

2009-01-01

This meta-analysis is examining the psychological effects of wintering-over in Antarctica. As an isolated, confined, and extreme (ICE) environment, Antarctica provides invaluable opportunities to experience stressors more common to spaceflight than to the average person s everyday life. Increased prevalence of psychological symptoms, syndromes, and psychiatric disorders, as well as positive effects, are expected to be associated with various demographic and environmental factors. Implications for spaceflight are discussed. Findings from statistical review of the Antarctic articles will be shared.

Impacts of the north and tropical Atlantic Ocean on the Antarctic Peninsula and sea ice.

Science.gov (United States)

Li, Xichen; Holland, David M; Gerber, Edwin P; Yoo, Changhyun

2014-01-23

In recent decades, Antarctica has experienced pronounced climate changes. The Antarctic Peninsula exhibited the strongest warming of any region on the planet, causing rapid changes in land ice. Additionally, in contrast to the sea-ice decline over the Arctic, Antarctic sea ice has not declined, but has instead undergone a perplexing redistribution. Antarctic climate is influenced by, among other factors, changes in radiative forcing and remote Pacific climate variability, but none explains the observed Antarctic Peninsula warming or the sea-ice redistribution in austral winter. However, in the north and tropical Atlantic Ocean, the Atlantic Multidecadal Oscillation (a leading mode of sea surface temperature variability) has been overlooked in this context. Here we show that sea surface warming related to the Atlantic Multidecadal Oscillation reduces the surface pressure in the Amundsen Sea and contributes to the observed dipole-like sea-ice redistribution between the Ross and Amundsen-Bellingshausen-Weddell seas and to the Antarctic Peninsula warming. Support for these findings comes from analysis of observational and reanalysis data, and independently from both comprehensive and idealized atmospheric model simulations. We suggest that the north and tropical Atlantic is important for projections of future climate change in Antarctica, and has the potential to affect the global thermohaline circulation and sea-level change.

Health aspects of Antarctic tourism.

Science.gov (United States)

Prociv, P

1998-12-01

Increasing numbers of seaborne tourists are visiting Antarctica, with most coming from the United States (3503 in 1996-97), Germany (777), and Australia (680; cf. 356 in 1994-95 and 410 in 1995-96). The impression among travel medicine clinicians is that, each year, more prospective travelers seek advice about the health demands of this type of adventure, mostly relating to fitness for travel, exposure to extreme cold, hazards in ice and snow, and other potential health risks. This is a recent phenomenon. While a regular shipping service had been established between the Falklands and the subantarctic islands of South Georgia and the South Shetlands by 1924, the first documented tourists accompanied an Argentine expedition to the South Orkneys in 1933.1 Commercial airline flights over these islands and the Antarctic Peninsula began in 1956, from Chile, and recreational cruises to the Peninsula began in 1958. Tourist numbers subsequently grew slowly, for what was clearly an exclusive and very expensive undertaking, with few ships available for these hazardous voyages. From 1957 to 1993, 37,000 tourists visited by sea, most seeing only the Peninsula.2 The dramatic recent growth in numbers is a consequence of the collapse of the Soviet Union. The small fleet of ice-strengthened research vessels and working icebreakers, which was made redundant by withdrawal of central government support from isolated communities and military activities along the northern coast of Siberia (and from Antarctic research bases), now accounts for the bulk of charter-cruise tourism to Antarctica, at competitive prices. According to the International Association of Antarctica Tour Operators,3 7322 people traveled to Antarctica on commercially organized voyages in the 1996-97 season, and a record 10,000 shipborne visitors were expected for the 1997-98 season (November-March), traveling mainly from South America to the Peninsula on 15 ice-reinforced vessels, each carrying between 36 and 180

Antarctic marine sediments as fingerprints of pollution migration

International Nuclear Information System (INIS)

Waheed, S.; Ahmad, S.; Rahman, A.; Qureshi, I.H.

2001-01-01

Forty elements in 21 coastal marine sediment samples collected during the second Antarctic scientific expedition from 18 different sites of Brekilen area located at the coast of Antarctica were analysed by instrumental neutron activation analysis (INAA) to detect eventual pollution. Radio-assay schemes for three sets of elements after neutron irradiation and cooling were evolved to avoid matrix effects. Data have been compared with those for sediments of various stations at Antarctica and two other regions in different continents. Lower concentration of certain elements in the Antarctic sediments reflects less environmental exposition. Enrichment factors (EF) were calculated for all the elements using the earth crust as reference matrix, based on elemental values by MASON, TAYLOR and WEDEPOHL which show a normal pattern near to unity expect for Ag and Br. The data obtained could also serve as a reference point from which changes in the global environment can be studied. The quality assurance of data was performed using standard reference materials (SRMs) of a similar matrix (IAEA Marine Sediment SD-M/TM and Chinese Marine Sediment GBW 07313). (author)

Microbial ecology and biogeochemistry of continental Antarctic soils.

Science.gov (United States)

Cowan, Don A; Makhalanyane, Thulani P; Dennis, Paul G; Hopkins, David W

2014-01-01

The Antarctica Dry Valleys are regarded as the coldest hyperarid desert system on Earth. While a wide variety of environmental stressors including very low minimum temperatures, frequent freeze-thaw cycles and low water availability impose severe limitations to life, suitable niches for abundant microbial colonization exist. Antarctic desert soils contain much higher levels of microbial diversity than previously thought. Edaphic niches, including cryptic and refuge habitats, microbial mats and permafrost soils all harbor microbial communities which drive key biogeochemical cycling processes. For example, lithobionts (hypoliths and endoliths) possess a genetic capacity for nitrogen and carbon cycling, polymer degradation, and other system processes. Nitrogen fixation rates of hypoliths, as assessed through acetylene reduction assays, suggest that these communities are a significant input source for nitrogen into these oligotrophic soils. Here we review aspects of microbial diversity in Antarctic soils with an emphasis on functionality and capacity. We assess current knowledge regarding adaptations to Antarctic soil environments and highlight the current threats to Antarctic desert soil communities.

Large-scale population assessment informs conservation management for seabirds in Antarctica and the Southern Ocean: A case study of Adélie penguins

Directory of Open Access Journals (Sweden)

Colin Southwell

2017-01-01

Full Text Available Antarctica and the Southern Ocean are increasingly affected by fisheries, climate change and human presence. Antarctic seabirds are vulnerable to all these threats because they depend on terrestrial and marine environments to breed and forage. We assess the current distribution and total abundance of Adélie penguins in East Antarctica and find there are 3.5 (95% CI 2.9–4.2 million individuals of breeding age along the East Antarctic coastline and 5.9 (4.2–7.7 million individuals foraging in the adjacent ocean after the breeding season. One third of the breeding population numbering over 1 million individuals breed within 10 km of research stations, highlighting the potential for human activities to impact Adélie penguin populations despite their current high abundance. The 16 Antarctic Specially Protected Areas currently designated in East Antarctica offer protection to breeding populations close to stations in four of six regional populations. The East Antarctic breeding population consumes an average of 193 500 tonnes of krill and 18 800 tonnes of fish during a breeding season, with consumption peaking at the end of the breeding season. These findings can inform future conservation management decisions in the terrestrial environment under the Protocol on Environmental Protection to develop a systematic network of protected areas, and in the marine environment under the Convention for the Conservation of Antarctic Marine Living Resources to allow the consumption needs of Adélie penguins to be taken into account when setting fishery catch limits. Extending this work to other penguin, flying seabird, seal and whale species is a priority for conservation management in Antarctica and the Southern Ocean.

Direct measurements of the light dependence of gross photosynthesis and oxygen consumption in the ocean

Science.gov (United States)

Bailleul, B.; Park, J.; Brown, C. M.; Bidle, K. D.; Lee, S.; Falkowski, P. G.

2016-02-01

For decades, a lack of understanding of how respiration is influenced by light has been stymying our ability to quantitatively analyze how phytoplankton allocate carbon in situ and the biological mechanisms that participate to the fate of blooms. Using membrane inlet mass spectrometry (MIMS), the light dependencies of gross photosynthesis and oxygen uptake rates were measured during the bloom demises of two prymnesiophytes, in two open ocean regions. In the North Atlantic, dominated by Emiliania huxleyi, respiration was independent of irradiance and was higher than the gross photosynthetic rate at all irradiances. In the Amundsen Sea (Antarctica), dominated by Phaeocystis antarctica, the situation was very different. Dark respiration was one order of magnitude lower than the maximal gross photosynthetic rate. ut the oxygen uptake rate increased by 10 fold at surface irradiances, where it becomes higher than gross photosynthesis. Our results suggest that the light dependence of oxygen uptake in P. antarctica has two sources: one is independent of photosynthesis, and is possibly associated with the photo-reduction of O2 mediated by dissolved organic matter; the second reflects the activity of an oxidase fueled in the light with photosynthetic electron flow. Interestingly, these dramatic light-dependent changes in oxygen uptake were not reproduced in nutrient-replete P. antarctica cultures, in the laboratory. Our measurements highlight the importance of improving our understanding of oxygen consuming reactions in the euphotic zone, which is critical to investigating the physiology of phytoplankton and tracing the fate of phytoplankton blooms.

Potential ash impact from Antarctic volcanoes: Insights from Deception Island's most recent eruption.

Science.gov (United States)

Geyer, A; Marti, A; Giralt, S; Folch, A

2017-11-28

Ash emitted during explosive volcanic eruptions may disperse over vast areas of the globe posing a threat to human health and infrastructures and causing significant disruption to air traffic. In Antarctica, at least five volcanoes have reported historic activity. However, no attention has been paid to the potential socio-economic and environmental consequences of an ash-forming eruption occurring at high southern latitudes. This work shows how ash from Antarctic volcanoes may pose a higher threat than previously believed. As a case study, we evaluate the potential impacts of ash for a given eruption scenario from Deception Island, one of the most active volcanoes in Antarctica. Numerical simulations using the novel MMB-MONARCH-ASH model demonstrate that volcanic ash emitted from Antarctic volcanoes could potentially encircle the globe, leading to significant consequences for global aviation safety. Results obtained recall the need for performing proper hazard assessment on Antarctic volcanoes, and are crucial for understanding the patterns of ash distribution at high southern latitudes with strong implications for tephrostratigraphy, which is pivotal to synchronize palaeoclimatic records.

Nrf2 and regulation of the antioxidant system in the Antarctic silverfish, Pleuragramma antarctica: Adaptation to environmental changes of pro-oxidant pressure.

Science.gov (United States)

Giuliani, Maria Elisa; Benedetti, Maura; Nigro, Marco; Regoli, Francesco

2017-08-01

Despite the key importance of Nrf2-Keap1 in regulating antioxidant system in vertebrates, this system is still poorly investigated in marine species. The present study focused on the Antarctic silverfish Pleuragramma antarctica which, during the final phases of embryo development in platelet ice, is challenged by a sudden enhancement of environmental oxidative conditions associated to ice melting. Partial coding sequences were identified for Nrf2, its repressor Keap1 and for typical Nrf2-target antioxidant genes, like catalase, glutathione peroxidase isoform 1 and Cu/Zn-dependent superoxide dismutase. Compared to temperate homologues, the protein sequences showed an elevated conservation of amino acids essential for catalytic functions, while a few specific substitutions in non-essential regions may represent a molecular adaptation to improve flexibility and accessibility to active site at cold temperatures. The role of the Nrf2-Keap1 pathway in modulating the activation of antioxidant defences was demonstrated at both transcriptional and functional levels with a clear temporal increase of antioxidant protection in embryos before the hatching. Such findings confirm the importance of Nrf2 and highlight regulation of antioxidants as an adaptive strategy in P. antarctica to protect the early life stages toward the environmental changes of pro-oxidant pressure. Copyright © 2017 Elsevier Ltd. All rights reserved.

Reaching consensus on Antarctic tourism regulation : Calibrating the human-nature relationship?

NARCIS (Netherlands)

Bastmeijer, Kees; Lamers, Machiel

2012-01-01

The states that jointly manage Antarctica were not yet able to reach consensus on a number of specific management issues relating to Antarctic tourism. While recognizing that many factors influence the international decision-making process, this publication aims to explore one rarely discussed

Reaching Consensus on Antarctic Tourism Regulation - Calibrating the Human-Nature Relationship?

NARCIS (Netherlands)

Bastmeijer, C.J.; Lamers, M.A.J.

2013-01-01

The states that jointly manage Antarctica were not yet able to reach consensus on a number of specific Antarctic tourism management issues. While recognizing that many factors influence the international decision-making process, this chapter aims to explore one rarely discussed philosophical factor

IODP Expedition 318: From Greenhouse to Icehouse at the Wilkes Land Antarctic Margin

Directory of Open Access Journals (Sweden)

Adam Klaus

2011-09-01

Full Text Available Integrated Ocean Drilling Program (IODP Expedition 318, Wilkes Land Glacial History, drilled a transect of sites across the Wilkes Land margin of Antarctica to provide a long-term record of the sedimentary archives of Cenozoic Antarctic glaciation and its intimate relationships with global climatic and oceanographic change. The Wilkes Land drilling program was undertaken to constrain the age, nature, and paleoenvironment of the previously only seismicallyinferred glacial sequences. The expedition (January–March 2010 recovered ~2000 meters of high-quality middle Eocene–Holocene sediments from water depths between 400 m and 4000 m at four sites on the Wilkes Land rise (U1355, U1356, U1359, and U1361 and three sites on the Wilkes Land shelf (U1357, U1358, and U1360. These records span ~53 million years of Antarctic history, and the various seismic units (WL-S4–WL-S9 have been successfully dated. The cores reveal the history of the Wilkes Land Antarctic margin from an ice-free “greenhouse” Antarctica, to the first cooling, to the onset and erosional consequences of the first glaciation and the subsequentdynamics of the waxing and waning ice sheets, all the way to thick, unprecedented “tree ring style” records with seasonal resolution of the last deglaciation that began ~10,000 y ago. The cores also reveal details of the tectonic history of the Australo-Antarctic Gulf from 53 Ma, portraying the onset of the second phase of rifting between Australia and Antarctica, to ever-subsiding margins and deepening,to the present continental and ever-widening ocean/continent configuration.

Seismic and thermal structure of the crust and uppermost mantle beneath Antarctica from inversion of multiple seismic datasets

Science.gov (United States)

Wiens, D.; Shen, W.; Anandakrishnan, S.; Aster, R. C.; Gerstoft, P.; Bromirski, P. D.; Dalziel, I.; Hansen, S. E.; Heeszel, D.; Huerta, A. D.; Nyblade, A.; Stephen, R. A.; Wilson, T. J.; Winberry, J. P.; Stern, T. A.

2017-12-01

Since the last decade of the 20th century, over 200 broadband seismic stations have been deployed across Antarctica (e.g., temporary networks such as TAMSEIS, AGAP/GAMSEIS, POLENET/ANET, TAMNNET and RIS/DRIS by U.S. geoscientists as well as stations deployed by Japan, Britain, China, Norway, and other countries). In this presentation, we discuss our recent efforts to build reference crustal and uppermost mantle shear velocity (Vs) and thermal models for continental Antarctica based on those seismic arrays. By combing the high resolution Rayleigh wave dispersion maps derived from both ambient noise and teleseismic earthquakes, together with P receiver function waveforms, we develop a 3-D Vs model for the crust and uppermost mantle beneath Central and West Antarctica to a depth of 200 km. Additionally, using this 3-D seismic model to constrain the crustal structure, we re-invert for the upper mantle thermal structure using the surface wave data within a thermodynamic framework and construct a 3-D thermal model for the Antarctic lithosphere. The final product, a high resolution thermal model together with associated uncertainty estimates from the Monte Carlo inversion, allows us to derive lithospheric thickness and surface heat flux maps for much of the continent. West Antarctica shows a much thinner lithosphere ( 50-90 km) than East Antarctica ( 130-230 km), with a sharp transition along the Transantarctic Mountains (TAM). A variety of geological features, including a slower/hotter but highly heterogeneous West Antarctica and a much faster/colder East Antarctic craton, are present in the 3-D seismic/thermal models. Notably, slow seismic velocities observed in the uppermost mantle beneath the southern TAM are interpreted as a signature of lithospheric foundering and replacement with hot asthenosphere. The high resolution image of these features from the 3-D models helps further investigation of the dynamic state of Antarctica's lithosphere and underlying asthenosphere

Photosynthetic limitations in two Antarctic vascular plants: importance of leaf anatomical traits and Rubisco kinetic parameters.

Science.gov (United States)

Sáez, Patricia L; Bravo, León A; Cavieres, Lohengrin A; Vallejos, Valentina; Sanhueza, Carolina; Font-Carrascosa, Marcel; Gil-Pelegrín, Eustaquio; Javier Peguero-Pina, José; Galmés, Jeroni

2017-05-17

Particular physiological traits allow the vascular plants Deschampsia antarctica Desv. and Colobanthus quitensis (Kunth) Bartl. to inhabit Antarctica. The photosynthetic performance of these species was evaluated in situ, focusing on diffusive and biochemical constraints to CO2 assimilation. Leaf gas exchange, Chl a fluorescence, leaf ultrastructure, and Rubisco catalytic properties were examined in plants growing on King George and Lagotellerie islands. In spite of the species- and population-specific effects of the measurement temperature on the main photosynthetic parameters, CO2 assimilation was highly limited by CO2 diffusion. In particular, the mesophyll conductance (gm)-estimated from both gas exchange and leaf chlorophyll fluorescence and modeled from leaf anatomy-was remarkably low, restricting CO2 diffusion and imposing the strongest constraint to CO2 acquisition. Rubisco presented a high specificity for CO2 as determined in vitro, suggesting a tight co-ordination between CO2 diffusion and leaf biochemistry that may be critical ultimately to optimize carbon balance in these species. Interestingly, both anatomical and biochemical traits resembled those described in plants from arid environments, providing a new insight into plant functional acclimation to extreme conditions. Understanding what actually limits photosynthesis in these species is important to anticipate their responses to the ongoing and predicted rapid warming in the Antarctic Peninsula. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Evaluating Potential Tipping Points of Antarctic basins

Science.gov (United States)

Durand, G.; Sainan, S.; Pattyn, F.; Jourdain, N.

2017-12-01

Antarctica is currently loosing mass and its forthcoming contribution to sea-level rise could substantially increase during the coming centuries. This is essentially due to geometrical constraints, i.e., in regions where grounded ice lies on a bedrock below sea-level sloping down towards the interior of the ice sheet (retrograde slope). For such a configuration the ice sheet is considered potentially unstable, as suggested by theory. However, recent observations on accelerated grounding-line retreat and new insights in modeling Pine Island and Thwaites glaciers give evidence that such self-sustained retreat, called marine ice sheet instability (MISI), has already been on its way. Although West Antarctica appears to be the most vulnerable region for MISI occurrence, similar topographic configurations are also observed in East Antarctica, in the Wilkes Basin in particular. Therefore, evaluating the MISI potential at a pan-Antarctic scale is becoming a priority. Here, using the f.ETISh ice sheet model, an ensemble of simulations of the entire contemporary Antarctic ice sheet has been carried out. In particular, we investigate the debuttressing of ice shelves required to initiate MISI for each coastal region around Antarctica by forcing the model with realistic sub-shelf melt pulses of varying duration and amplitude. We further identify the currently grounded areas where the outlet glaciers could hardly stabilize, the Amundsen Sea Sector being the more prone to large self-sustained retreats. On the contrary, the ability of Cook and Ninnis ice shelves to recover after large perturbations and enough buttress upstream outlet glaciers tends to limit self-sustained retreat of the sector. For each basin, rates of contribution to sea-level rise are discussed together with the RCPs and time when tipping points could be reached and MISI triggered.

Multichannel Seismic Reflection Data - SCAR - Antarctic Peninsula 1987-88, SDLS CD-ROM vol 24

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — These data are stacked multichannel marine seismic reflection data recorded during 1987-88 in the Antarctic Peninsula, Antarctica, by the Japan National Oil...

Multichannel Seismic Reflection Data - SCAR - Antarctic Peninsula - 1988-1989, SDLS CD-ROM vol 25

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — These data are stacked multichannel marine seismic reflection data recorded during 1988-89 in the Antarctic Peninsula, Antarctica, by the Japan National Oil...

Contemporary reliance on bicarbonate acquisition predicts increased growth of seagrass Amphibolis antarctica in a high-CO2 world.

Science.gov (United States)

Burnell, Owen W; Connell, Sean D; Irving, Andrew D; Watling, Jennifer R; Russell, Bayden D

2014-01-01

Rising atmospheric CO2 is increasing the availability of dissolved CO2 in the ocean relative to HCO3 (-). Currently, many marine primary producers use HCO3 (-) for photosynthesis, but this is energetically costly. Increasing passive CO2 uptake relative to HCO3 (-) pathways could provide energy savings, leading to increased productivity and growth of marine plants. Inorganic carbon-uptake mechanisms in the seagrass Amphibolis antarctica were determined using the carbonic anhydrase inhibitor acetazolamide (AZ) and the buffer tris(hydroxymethyl)aminomethane (TRIS). Amphibolis antarctica seedlings were also maintained in current and forecasted CO2 concentrations to measure their physiology and growth. Photosynthesis of A. antarctica was significantly reduced by AZ and TRIS, indicating utilization of HCO3 (-)-uptake mechanisms. When acclimated plants were switched between CO2 treatments, the photosynthetic rate was dependent on measurement conditions but not growth conditions, indicating a dynamic response to changes in dissolved CO2 concentration, rather than lasting effects of acclimation. At forecast CO2 concentrations, seedlings had a greater maximum electron transport rate (1.4-fold), photosynthesis (2.1-fold), below-ground biomass (1.7-fold) and increase in leaf number (2-fold) relative to plants in the current CO2 concentration. The greater increase in photosynthesis (measured as O2 production) compared with the electron transport rate at forecasted CO2 concentration suggests that photosynthetic efficiency increased, possibly due to a decrease in photorespiration. Thus, it appears that the photosynthesis and growth of seagrasses reliant on energetically costly HCO3 (-) acquisition, such as A. antarctica, might increase at forecasted CO2 concentrations. Greater growth might enhance the future prosperity and rehabilitation of these important habitat-forming plants, which have experienced declines of global significance.

Optical observations of LIGO source GW 170817 by the Antarctic Survey Telescopes at Dome A, Antarctica

Science.gov (United States)

Hu, Lei; Wu, Xuefeng; Andreoni, Igor; Ashley, Michael C. B.; Cooke, Jeff; Cui, Xiangqun; Du, Fujia; Dai, Zigao; Gu, Bozhong; Hu, Yi; Lu, Haiping; Li, Xiaoyan; Li, Zhengyang; Liang, Ensi; Liu, Liangduan; Ma, Bin; Shang, Zhaohui; Sun, Tianrui; Suntzeff, N. B.; Tao, Charling; Udden, Syed A.; Wang, Lifan; Wang, Xiaofeng; Wen, Haikun; Xiao, Di; Su, Jin; Yang, Ji; Yang, Shihai; Yuan, Xiangyan; Zhou, Hongyan; Zhang, Hui; Zhou, Jilin; Zhu, Zonghong

2017-10-01

The LIGO detection of gravitational waves (GW) from merging black holes in 2015 marked the beginning of a new era in observational astronomy. The detection of an electromagnetic signal from a GW source is the critical next step to explore in detail the physics involved. The Antarctic Survey Telescopes (AST3), located at Dome A, Antarctica, is uniquely situated for rapid response time-domain astronomy with its continuous night-time coverage during the austral winter. We report optical observations of the GW source (GW 170817) in the nearby galaxy NGC 4993 using AST3. The data show a rapidly fading transient at around 1 day after the GW trigger, with the i-band magnitude declining from 17.23±0.13 magnitude to 17.72±0.09 magnitude in ˜ 0.8 hour. The brightness and time evolution of the optical transient associated with GW 170817 are broadly consistent with the predictions of models involving merging binary neutron stars. We infer from our data that the merging process ejected about ˜ 10^{-2} solar mass of radioactive material at a speed of up to 30% the speed of light.

A Roadmap for Antarctic and Southern Ocean Science for the Next Two Decades and Beyond

Science.gov (United States)

Kennicutt, M. C., II

2015-12-01

Abstract: Antarctic and Southern Ocean science is vital to understanding natural variability, the processes that govern global change and the role of humans in the Earth and climate system. The potential for new knowledge to be gained from future Antarctic science is substantial. Therefore, the international Antarctic community came together to 'scan the horizon' to identify the highest priority scientific questions that researchers should aspire to answer in the next two decades and beyond. Wide consultation was a fundamental principle for the development of a collective, international view of the most important future directions in Antarctic science. From the many possibilities, the horizon scan identified 80 key scientific questions through structured debate, discussion, revision and voting. Questions were clustered into seven topics: i) Antarctic atmosphere and global connections, ii) Southern Ocean and sea ice in a warming world, iii) ice sheet and sea level, iv) the dynamic Earth, v) life on the precipice, vi) near-Earth space and beyond, and vii) human presence in Antarctica. Answering the questions identified by the horizon scan will require innovative experimental designs, novel applications of technology, invention of next-generation field and laboratory approaches, and expanded observing systems and networks. Unbiased, non-contaminating procedures will be required to retrieve the requisite air, biota, sediment, rock, ice and water samples. Sustained year-round access to Antarctica and the Southern Ocean will be essential to increase winter-time measurements. Improved models are needed that represent Antarctica and the Southern Ocean in the Earth System, and provide predictions at spatial and temporal resolutions useful for decision making. A co-ordinated portfolio of cross-disciplinary science, based on new models of international collaboration, will be essential as no scientist, programme or nation can realize these aspirations alone.

First record of Babesia sp. in Antarctic penguins.

Science.gov (United States)

Montero, Estrella; González, Luis Miguel; Chaparro, Alberto; Benzal, Jesús; Bertellotti, Marcelo; Masero, José A; Colominas-Ciuró, Roger; Vidal, Virginia; Barbosa, Andrés

2016-04-01

This is the first reported case of Babesia sp. in Antarctic penguins, specifically a population of Chinstrap penguins (Pygoscelis antarctica) in the Vapour Col penguin rookery in Deception Island, South Shetlands, Antarctica. We collected peripheral blood from 50 adult and 30 chick Chinstrap penguins. Examination of the samples by microscopy showed intraerythrocytic forms morphologically similar to other avian Babesia species in 12 Chinstrap penguin adults and seven chicks. The estimated parasitaemias ranged from 0.25×10(-2)% to 0.75×10(-2)%. Despite the low number of parasites found in blood smears, semi-nested PCR assays yielded a 274 bp fragment in 12 of the 19 positive blood samples found by microscopy. Sequencing revealed that the fragment was 97% similar to Babesia sp. 18S rRNA from Australian Little Penguins (Eudyptula minor) confirming presence of the parasite. Parasite prevalence estimated by microscopy in adults and chicks was higher (24% vs. 23.3%, respectively) than found by semi-nested PCR (16% vs. 13.3% respectively). Although sampled penguins were apparently healthy, the effect of Babesia infection in these penguins is unknown. The identification of Babesia sp. in Antarctic penguins is an important finding. Ixodes uriae, as the only tick species present in the Antarctic Peninsula, is the key to understanding the natural history of this parasite. Future work should address the transmission dynamics and pathogenicity of Babesia sp. in Chinstrap penguin as well as in other penguin species, such as Gentoo penguin (Pygoscelis papua) and Adélie penguin (Pygoscelis adeliae), present within the tick distribution range in the Antarctic Peninsula. Copyright © 2016 Elsevier GmbH. All rights reserved.

Estimates of numbers of kelp gulls and Kerguelen and Antarctic ...

African Journals Online (AJOL)

Four species are regular breeders at the islands: Subantarctic skua Catharacta antarctica, kelp gull Larus dominicanus, Antarctic tern Sterna vittata and Kerguelen tern S. virgata. The latter three species currently each have populations of below 150 breeding pairs at the islands. Kelp gull numbers appear to be relatively ...

ARM West Antarctic Radiation Experiment (AWARE) Science Plan

Energy Technology Data Exchange (ETDEWEB)

Lubin, D [National Science Foundation; Bromwich, DH [Ohio State University; Russell, LM [Scripps Institution of Oceanography; Verlinde, J [The Pennsylvania State University; Vogelmann, AM [Brookhaven National Laboratory

2015-10-01

West Antarctica is one of the most rapidly warming regions on Earth, and this warming is closely connected with global sea level rise. The discovery of rapid climate change on the West Antarctic Ice Sheet (WAIS) has challenged previous explanations of Antarctic climate change that focused on strengthening of circumpolar westerlies in response to the positive polarity trend in the Southern Annular Mode. West Antarctic warming does not yet have a comprehensive explanation: dynamical mechanisms may vary from one season to the next, and these mechanisms very likely involve complex teleconnections with subtropical and tropical latitudes. The prime motivation for this proposal is that there has been no substantial atmospheric science or climatological field work on West Antarctica since the 1957 International Geophysical Year and that research continued for only a few years. Direct meteorological information on the WAIS has been limited to a few automatic weather stations for several decades, yet satellite imagery and meteorological reanalyses indicate that West Antarctica is highly susceptible to advection of warm and moist maritime air with related cloud cover, depending on the location and strength of low pressure cells in the Amundsen, Ross, and Bellingshausen Seas. There is a need to quantify the role of these changing air masses on the surface energy balance, including all surface energy components and cloud-radiative forcing. More generally, global climate model simulations are known to perform poorly over the Antarctic and Southern Oceans, and the marked scarcity of cloud information at southern high latitudes has so far inhibited significant progress. Fortunately, McMurdo Station, where the Atmospheric Radiation Measurement Facility’s (ARM’s) most advanced cloud and aerosol instrumentation is situated, has a meteorological relationship with the WAIS via circulation patterns in the Ross and Amundsen Seas. We can therefore gather sophisticated data with cloud

Expression of genes involved in energy mobilization and osmoprotectant synthesis during thermal and dehydration stress in the Antarctic midge, Belgica antarctica.

Science.gov (United States)

Teets, Nicholas M; Kawarasaki, Yuta; Lee, Richard E; Denlinger, David L

2013-02-01

The Antarctic midge, Belgica antarctica, experiences sub-zero temperatures and desiccating conditions for much of the year, and in response to these environmental insults, larvae undergo rapid shifts in metabolism, mobilizing carbohydrate energy reserves to promote synthesis of low-molecular-mass osmoprotectants. In this study, we measured the expression of 11 metabolic genes in response to thermal and dehydration stress. During both heat and cold stress, we observed upregulation of phosphoenolpyruvate carboxykinase (pepck) and glycogen phosphorylase (gp) to support rapid glucose mobilization. In contrast, there was a general downregulation of pathways related to polyol, trehalose, and proline synthesis during both high- and low-temperature stress. Pepck was likewise upregulated in response to different types of dehydration stress; however, for many of the other genes, expression patterns depended on the nature of dehydration stress. Following fast dehydration, expression patterns were similar to those observed during thermal stress, i.e., upregulation of gp accompanied by downregulation of trehalose and proline synthetic genes. In contrast, gradual, prolonged dehydration (both at a constant temperature and in conjunction with chilling) promoted marked upregulation of genes responsible for trehalose and proline synthesis. On the whole, our data agree with known metabolic adaptations to stress in B. antarctica, although a few discrepancies between gene expression patterns and downstream metabolite contents point to fluxes that are not controlled at the level of transcription.

Radio Echo Sounding (RES investigations at Talos Dome (East Antarctica: bedrock topography and ice thickness

Directory of Open Access Journals (Sweden)

I. E. Tabacco

2003-06-01

Full Text Available Radio echo sounding measurements were collected during two Antarctic expeditions to determine the ice thickness and the sub-glacial morphology of Talos Dome in the region around 72°48'S; 159°06'E (about 6400 km2 on the edge of the East Antarctic plateau adjacent to Victoria Land in the western Ross Sea sector. The increasing interest in this region is due to the fact that in this area the ice accumulation is higher than in other sites in East Antarctica. Because of this, Talos Dome could be a new site for a project of a deep ice core drilling to obtain information on climate changes near the coast of Antarctica. In this frame, the knowledge of the bedrock topography is of great importance to choose the best location for the drilling site. In this paper, airborne radio echo sounding results from two Antarctic expeditions (1997 and 1999 are presented. Bedrock topography in bi- and three-dimensions for the Talos Dome region are discussed.

Basin-scale heterogeneity in Antarctic precipitation and its impact on surface mass variability

Directory of Open Access Journals (Sweden)

J. Fyke

2017-11-01

Full Text Available Annually averaged precipitation in the form of snow, the dominant term of the Antarctic Ice Sheet surface mass balance, displays large spatial and temporal variability. Here we present an analysis of spatial patterns of regional Antarctic precipitation variability and their impact on integrated Antarctic surface mass balance variability simulated as part of a preindustrial 1800-year global, fully coupled Community Earth System Model simulation. Correlation and composite analyses based on this output allow for a robust exploration of Antarctic precipitation variability. We identify statistically significant relationships between precipitation patterns across Antarctica that are corroborated by climate reanalyses, regional modeling and ice core records. These patterns are driven by variability in large-scale atmospheric moisture transport, which itself is characterized by decadal- to centennial-scale oscillations around the long-term mean. We suggest that this heterogeneity in Antarctic precipitation variability has a dampening effect on overall Antarctic surface mass balance variability, with implications for regulation of Antarctic-sourced sea level variability, detection of an emergent anthropogenic signal in Antarctic mass trends and identification of Antarctic mass loss accelerations.

[Distribution of bacteria of Methylobacterium genus in the terrestrial biotopes of the Antarctic region].

Science.gov (United States)

Romanovskaia, V A; Rokitko, P V; Shilin, S O; Chernaia, N A; Tashirev, A B

2009-01-01

Methylotrophs distribution has been studied in the terrestrial biotopes (moss, lichen, grass, soil, sludge of lakes) on the islands of Galindez, Barkhans, Irizar, Uruguay, Jalour, Petermann, Berthelot, Cruls, King George, Corner, Skua located in the Pacific sector of the Antarctic Region, as well as in analogous biotopes on the western shore of the Antarctic peninsula Basing on a complex of diagnosis features the isolated pink-pigmented strains, which facultatively use methanol and realize the serine cycle of assimilation of one-carbon compounds, are attributed to Methylobacterium genus. Methylobacterium strains occur more often in mosses, grass Deschampsia antarctica and lichens, than in the soil and lake sludge. Some regions ofAntarctica are comparable by the number of Methylobacterium cells with the same in the regions with moderate climate. An analysis of gene sequences 16S rRNA of the Antarctic methylobacteria with those of GenBank has shown a high extent of similarity with Methylobacterium extorquens (99.4-99.7%). Notwithstanding that the strains of Methylobacterium are resistant to the broad range of extreme factors (gamma-irradiation, UV-irradiation, dehydration), the Antarctic and collection strains of the genus were sensitive to the ions of such heavy metals as Cu, Hg, Cd, Cr (10 mg/l).

Use of antarctic analogs to support the space exploration initiative

Science.gov (United States)

Wharton, Robert; Roberts, Barney; Chiang, Erick; Lynch, John; Roberts, Carol; Buoni, Corinne; Andersen, Dale

1990-01-01

This report has discussed the Space Exploration Initiative (SEI) and the U.S. Antarctic Program (USAP) in the context of assessing the potential rationale and strategy for conducting a cooperative NASA/NSF (National Science Foundation) effort. Specifically, such an effort would address shared research and data on living and conducting scientific research in isolated, confined, hostile, and remote environments. A review of the respective goals and requirements of NASA and the NSF indicates that numerous opportunities exist to mutually benefit from sharing relevant technologies, data, and systems. Two major conclusions can be drawn: (1) The technologies, experience, and capabilities existing and developing in the aerospace community would enhance scientific research capabilities and the efficiency and effectiveness of operations in Antarctica. The transfer and application of critical technologies (e.g., power, waste management, life support) and collaboration on crew research needs (e.g., human behavior and medical support needs) would streamline the USAP operations and provide the scientific community with advancements in facilities and tools for Antarctic research. (2) Antarctica is the most appropriate earth analog for the environments of the the Moon and Mars. Using Antarctica in this way would contribute substantially to near- and long-term needs and plans for the SEI. Antarctica is one of the few ground-based analogs that would permit comprehensive and integrated studies of three areas deemed critical to productive and safe operations on the Moon and Mars: human health and productivity; innovative scientific research techniques; and reliable, efficient technologies and facilities.

ADMAP-2: The next-generation Antarctic magnetic anomaly map

Science.gov (United States)

Golynsky, Alexander; Golynsky, Dmitry; Ferraccioli, Fausto; Jordan, Tom; Damaske, Detlef; Blankenship, Don; Holt, Jack; Young, Duncan; Ivanov, Sergey; Kiselev, Alexander; Jokat, Wilfried; Gohl, Karsten; Eagles, Graeme; Bell, Robin; Armadillo, Egidio; Bozzo, Emanuelle; Caneva, Giorgio; Finn, Carol; Forsberg, Rene; Aitken, Alan

2017-04-01

The Antarctic Digital Magnetic Anomaly Project compiled the first international magnetic anomaly map of the Antarctic region south of 60°S (ADMAP-1) some six years after its 1995 launch (Golynsky et al., 2001; Golynsky et al., 2007; von Frese et al., 2007). This magnetic anomaly compilation provided new insights into the structure and evolution of Antarctica, including its Proterozoic-Archaean cratons, Proterozoic-Palaeozoic orogens, Palaeozoic-Cenozoic magmatic arc systems, continental rift systems and rifted margins, large igneous provinces and the surrounding oceanic gateways. The international working group produced the ADMAP-1 database from more than 1.5 million line-kilometres of terrestrial, airborne, marine and satellite magnetic observations collected during the IGY 1957-58 through 1999. Since the publication of the first magnetic anomaly map, the international geomagnetic community has acquired more than 1.9 million line-km of new airborne and marine data. This implies that the amount of magnetic anomaly data over the Antarctic continent has more than doubled. These new data provide important constraints on the geology of the enigmatic Gamburtsev Subglacial Mountains and Prince Charles Mountains, Wilkes Land, Dronning Maud Land, and other largely unexplored Antarctic areas (Ferraccioli et al., 2011, Aitken et al., 2014¸ Mieth & Jokat, 2014, Golynsky et al., 2013). The processing of the recently acquired data involved quality assessments by careful statistical analysis of the crossover errors. All magnetic data used in the ADMAP-2 compilation were delivered as profiles, although several of them were in raw form. Some datasets were decimated or upward continued to altitudes of 4 km or higher with the higher frequency geological signals smoothed out. The line data used for the ADMAP-1 compilation were reprocessed for obvious errors and residual corrugations. The new near-surface magnetic data were corrected for the international geomagnetic reference field

Coastal-change and glaciological map of the Eights Coast area, Antarctica, 1972-2001

Science.gov (United States)

Swithinbank, Charles; Williams, Richard S.; Ferrigno, Jane G.; Foley, Kevin M.; Rosanova, Christine E.; Dailide, Lina M.

2004-01-01

Changes in the area and volume of polar ice sheets are intricately linked to changes in global climate, and the resulting changes in sea level may severely impact the densely populated coastal regions on Earth. Melting of the West Antarctic part alone of the Antarctic ice sheet could cause a sea-level rise of approximately 6 meters (m). The potential sea-level rise after melting of the entire Antarctic ice sheet is estimated to be 65 m (Lythe and others, 2001) to 73 m (Williams and Hall, 1993). In spite of its importance, the mass balance (the net volumetric gain or loss) of the Antarctic ice sheet is poorly known; it is not known for certain whether the ice sheet is growing or shrinking. In a review paper, Rignot and Thomas (2002) concluded that the West Antarctic part of the Antarctic ice sheet is probably becoming thinner overall; although the western part is thickening, the northern part is thinning. Joughin and Tulaczyk (2002), based on analysis of ice-flow velocities derived from synthetic aperture radar, concluded that most of the Ross ice streams (ice streams on the east side of the Ross Ice Shelf) have a positive mass balance. The mass balance of the East Antarctic is unknown, but thought to be in near equilibrium. Measurement of changes in area and mass balance of the Antarctic ice sheet was given a very high priority in recommendations by the Polar Research Board of the National Research Council (1986), in subsequent recommendations by the Scientific Committee on Antarctic Research (SCAR) (1989, 1993), and by the National Science Foundation's (1990) Division of Polar Programs. On the basis of these recommendations, the U.S. Geological Survey (USGS) decided that the archive of early 1970s Landsat 1, 2, and 3 Multispectral Scanner (MSS) images of Antarctica and the subsequent repeat coverage made possible with Landsat and other satellite images provided an excellent means of documenting changes in the coastline of Antarctica (Ferrigno and Gould, 1987). The

Coastal-change and glaciological map of the Saunders Coast area, Antarctica; 1972-1997

Science.gov (United States)

Swithinbank, Charles; Williams, Richard S.; Ferrigno, Jane G.; Foley, Kevin M.; Hallam, Cheryl A.; Rosanova, Christine E.

2003-01-01

Changes in the area and volume of polar ice sheets are intricately linked to changes in global climate, and the resulting changes in sea level may severely impact the densely populated coastal regions on Earth. Melting of the West Antarctic part alone of the Antarctic ice sheet could cause a sea-level rise of approximately 6 meters (m). The potential sea-level rise after melting of the entire Antarctic ice sheet is estimated to be 65 m (Lythe and others, 2001) to 73 m (Williams and Hall, 1993). In spite of its importance, the mass balance (the net volumetric gain or loss) of the Antarctic ice sheet is poorly known; it is not known for certain whether the ice sheet is growing or shrinking. In a review paper, Rignot and Thomas (2002) concluded that the West Antarctic part of the Antarctic ice sheet is probably becoming thinner overall; although the western part is thickening, the northern part is thinning. Joughin and Tulaczyk (2002), based on analysis of ice-flow velocities derived from synthetic aperture radar, concluded that most of the Ross ice streams (ice streams on the east side of the Ross Ice Shelf) have a positive mass balance. The mass balance of the East Antarctic is unknown, but thought to be in near equilibrium. Measurement of changes in area and mass balance of the Antarctic ice sheet was given a very high priority in recommendations by the Polar Research Board of the National Research Council (1986), in subsequent recommendations by the Scientific Committee on Antarctic Research (SCAR) (1989, 1993), and by the National Science Foundation?s (1990) Division of Polar Programs. On the basis of these recommendations, the U.S. Geological Survey (USGS) decided that the archive of early 1970s Landsat 1, 2, and 3 Multispectral Scanner (MSS) images of Antarctica and the subsequent repeat coverage made possible with Landsat and other satellite images provided an excellent means of documenting changes in the coastline of Antarctica (Ferrigno and Gould, 1987). The

Concentration of trace elements in feathers of three Antarctic penguins: Geographical and interspecific differences

Energy Technology Data Exchange (ETDEWEB)

Jerez, Silvia [Area de Toxicologia, Facultad de Veterinaria, Universidad de Murcia, Campus de Espinardo, 30100 Murcia (Spain); Motas, Miguel, E-mail: motas@um.es [Area de Toxicologia, Facultad de Veterinaria, Universidad de Murcia, Campus de Espinardo, 30100 Murcia (Spain); Palacios, Maria Jose; Valera, Francisco [Departamento de Ecologia Funcional y Evolutiva, Estacion Experimental de Zonas Aridas, CSIC, Carretera de Sacramento s/n, 04120 La Canada de San Urbano, Almeria (Spain); Cuervo, Jose Javier; Barbosa, Andres [Departamento de Ecologia Funcional y Evolutiva, Estacion Experimental de Zonas Aridas, CSIC, Carretera de Sacramento s/n, 04120 La Canada de San Urbano, Almeria (Spain); Departamento de Ecologia Evolutiva, Museo Nacional de Ciencias Naturales, CSIC, C/Jose Gutierrez Abascal 2, 28006 Madrid (Spain)

2011-10-15

Antarctica is often considered as one of the last pristine regions, but it could be affected by pollution at global and local scale. Concentrations of Al, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Cd and Pb were determinated by ICP-MS in feathers (n = 207 individuals) of gentoo, chinstrap and Adelie penguin collected in 8 locations throughout the Antarctic Peninsula (2006-2007). The highest levels of several elements were found in samples from King George Island (8.08, 20.29 and 1.76 {mu}g g{sup -1} dw for Cr, Cu and Pb, respectively) and Deception Island (203.13, 3.26 and 164.26 {mu}g g{sup -1} dw for Al, Mn and Fe, respectively), where probably human activities and large-scale transport of pollutants contribute to increase metal levels. Concentrations of Cr, Mn, Cu, Se or Pb, which are similar to others found in different regions of the world, show that some areas in Antarctica are not utterly pristine. - Highlights: > We study levels of trace elements in feathers of Antarctic penguins. > Eight different rookeries throughout the Antarctic Peninsula were sampled. > Interspecific (gentoo, chinstrap, Adelie) and geographical differences were tested. > Relatively high metal levels were found in areas with major human presence. > Penguin feather can be useful for metals monitoring in the Antarctic environment. - Trace element levels in feathers of three penguin species from the Antarctic Peninsula indicate the presence of pollution in certain locations.

Concentration of trace elements in feathers of three Antarctic penguins: Geographical and interspecific differences

International Nuclear Information System (INIS)

Jerez, Silvia; Motas, Miguel; Palacios, Maria Jose; Valera, Francisco; Cuervo, Jose Javier; Barbosa, Andres

2011-01-01

Antarctica is often considered as one of the last pristine regions, but it could be affected by pollution at global and local scale. Concentrations of Al, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Cd and Pb were determinated by ICP-MS in feathers (n = 207 individuals) of gentoo, chinstrap and Adelie penguin collected in 8 locations throughout the Antarctic Peninsula (2006-2007). The highest levels of several elements were found in samples from King George Island (8.08, 20.29 and 1.76 μg g -1 dw for Cr, Cu and Pb, respectively) and Deception Island (203.13, 3.26 and 164.26 μg g -1 dw for Al, Mn and Fe, respectively), where probably human activities and large-scale transport of pollutants contribute to increase metal levels. Concentrations of Cr, Mn, Cu, Se or Pb, which are similar to others found in different regions of the world, show that some areas in Antarctica are not utterly pristine. - Highlights: → We study levels of trace elements in feathers of Antarctic penguins. → Eight different rookeries throughout the Antarctic Peninsula were sampled. → Interspecific (gentoo, chinstrap, Adelie) and geographical differences were tested. → Relatively high metal levels were found in areas with major human presence. → Penguin feather can be useful for metals monitoring in the Antarctic environment. - Trace element levels in feathers of three penguin species from the Antarctic Peninsula indicate the presence of pollution in certain locations.

Microbial ecology and biogeochemistry of continental Antarctic soils

Directory of Open Access Journals (Sweden)

Don A Cowan

2014-04-01

Full Text Available The Antarctica Dry Valleys are regarded as the coldest hyperarid desert system on Earth. While a wide variety of environmental stressors including very low minimum temperatures, frequent freeze-thaw cycles and low water availability impose severe limitations to life, suitable niches for abundant microbial colonization exist. Antarctic desert soils contain much higher levels of microbial diversity than previously thought. Edaphic niches, including cryptic and refuge habitats, microbial mats and permafrost soils all harbour microbial communities which drive key biogeochemical cycling processes. For example, lithobionts (hypoliths and endoliths possess a genetic capacity for nitrogen and carbon cycling, polymer degradation and other system processes. Nitrogen fixation rates of hypoliths, as assessed through acetylene reduction assays, suggest that these communities are a significant input source for nitrogen into these oligotrophic soils. Here we review aspects of microbial diversity in Antarctic soils with an emphasis on functionality and capacity. We assess current knowledge regarding adaptations to Antarctic soil environments and highlight the current threats to Antarctic desert soil communities.

Spatial Patterns of Variability in Antarctic Surface Temperature: Connections to the Southern Hemisphere Annular Mode and the Southern Oscillation

Science.gov (United States)

Kwok, Ron; Comiso, Josefino C.; Koblinsky, Chester J. (Technical Monitor)

2002-01-01

The 17-year (1982-1998) trend in surface temperature shows a general cooling over the Antarctic continent, warming of the sea ice zone, with moderate changes over the oceans. Warming of the peripheral seas is associated with negative trends in the regional sea ice extent. Effects of the Southern Hemisphere Annular Mode (SAM) and the extrapolar Southern Oscillation (SO) on surface temperature are quantified through regression analysis. Positive polarities of the SAM are associated with cold anomalies over most of Antarctica, with the most notable exception of the Antarctic Peninsula. Positive temperature anomalies and ice edge retreat in the Pacific sector are associated with El Nino episodes. Over the past two decades, the drift towards high polarity in the SAM and negative polarity in the SO indices couple to produce a spatial pattern with warmer temperatures in the Antarctic Peninsula and peripheral seas, and cooler temperatures over much of East Antarctica.

A STUDY ON SNOW PROFILES AND SURFACE CHARACTERISTICS ALONG 6000km TRANSANTARCTIC ROUTE (Ⅰ)——THE "1990 INTERNATIONAL TRANS-ANTARCTIC EXPEDITION" GLACIOLOGICAL RESEARCH

Institute of Scientific and Technical Information of China (English)

秦大河; 任贾文

1992-01-01

Along a 5986 km route on Antarctic ice sheet from west to east, 106 snow pits with a depth ranging from 1.0—2.0 m have been dug by the first author of this paper, the Chinese member of the "1990 International Trans-Antarctic Expedition". The basic physical characteristics of the surface layer of the ice sheet on a large scale are obtained through the observations of snow profiles at these snow pits. The sastrugi shapes and major axis azimuths have also been observed or measured on the way. Analysis for these observation data shows that in West Antarctica the meltwater infiltration-congelation is obvious and the annual precipitation is larger than that in East Antarctica, which implies that climate in West Antarctica is warmer, more humid and influenced more greatly by the South Ocean than that in East Antarctica. Radiation ice-glazes frequently found in snow profiles indicate that even in East Antarctica under very low temperatures, surface "melting" occurs in summer due to the long-time solar radiatio

Time series analysis of the Antarctic Circumpolar Wave via symbolic transfer entropy

Science.gov (United States)

Oh, Mingi; Kim, Sehyun; Lim, Kyuseong; Kim, Soo Yong

2018-06-01

An attempt to interpret a large-scale climate phenomenon in the Southern Ocean (SO), the Antarctic Circumpolar Wave (ACW), has been made using an information entropy method, symbolic transfer entropy (STE). Over the areas of 50-60∘S latitude belt, information flow for four climate variables, sea surface temperature (SST), sea-ice edge (SIE), sea level pressure (SLP) and meridional wind speed (MWS) is examined. We found a tendency that eastward flow of information is preferred only for oceanic variables, which is a main characteristic of the ACW, an eastward wave making a circuit around the Antarctica. Since the ACW is the coherent pattern in both ocean and atmosphere it is reasonable to infer that the tendency reflects the Antarctic Circumpolar Current (ACC) encircling the Antarctica, rather than an evidence of the ACW. We observed one common feature for all four variables, a strong information flow over the area of the eastern Pacific Ocean, which suggest a signature of El Nino Southern Oscillation (ENSO).

Crystal structure and enzymatic properties of chalcone isomerase from the Antarctic vascular plant Deschampsia antarctica Desv.

Science.gov (United States)

Park, Sun-Ha; Lee, Chang Woo; Cho, Sung Mi; Lee, Hyoungseok; Park, Hyun; Lee, Jungeun; Lee, Jun Hyuck

2018-01-01

Chalcone isomerase (CHI) is an important enzyme for flavonoid biosynthesis that catalyzes the intramolecular cyclization of chalcones into (S)-flavanones. CHIs have been classified into two types based on their substrate specificity. Type I CHIs use naringenin chalcone as a substrate and are found in most of plants besides legumes, whereas type II CHIs in leguminous plants can also utilize isoliquiritigenin. In this study, we found that the CHI from the Antarctic plant Deschampsia antarctica (DaCHI1) is of type I based on sequence homology but can use type II CHI substrates. To clarify the enzymatic mechanism of DaCHI1 at the molecular level, the crystal structures of unliganded DaCHI1 and isoliquiritigenin-bound DaCHI1 were determined at 2.7 and 2.1 Å resolutions, respectively. The structures revealed that isoliquiritigenin binds to the active site of DaCHI1 and induces conformational changes. Additionally, the activity assay showed that while DaCHI1 exhibits substrate preference for naringenin chalcone, it can also utilize isoliquiritigenin although the catalytic activity was relatively low. Based on these results, we propose that DaCHI1 uses various substrates to produce antioxidant flavonoids as an adaptation to oxidative stresses associated with harsh environmental conditions.

Crystal structure and enzymatic properties of chalcone isomerase from the Antarctic vascular plant Deschampsia antarctica Desv.

Directory of Open Access Journals (Sweden)

Sun-Ha Park

Full Text Available Chalcone isomerase (CHI is an important enzyme for flavonoid biosynthesis that catalyzes the intramolecular cyclization of chalcones into (S-flavanones. CHIs have been classified into two types based on their substrate specificity. Type I CHIs use naringenin chalcone as a substrate and are found in most of plants besides legumes, whereas type II CHIs in leguminous plants can also utilize isoliquiritigenin. In this study, we found that the CHI from the Antarctic plant Deschampsia antarctica (DaCHI1 is of type I based on sequence homology but can use type II CHI substrates. To clarify the enzymatic mechanism of DaCHI1 at the molecular level, the crystal structures of unliganded DaCHI1 and isoliquiritigenin-bound DaCHI1 were determined at 2.7 and 2.1 Å resolutions, respectively. The structures revealed that isoliquiritigenin binds to the active site of DaCHI1 and induces conformational changes. Additionally, the activity assay showed that while DaCHI1 exhibits substrate preference for naringenin chalcone, it can also utilize isoliquiritigenin although the catalytic activity was relatively low. Based on these results, we propose that DaCHI1 uses various substrates to produce antioxidant flavonoids as an adaptation to oxidative stresses associated with harsh environmental conditions.

Gravity Maps of Antarctic Lithospheric Structure from Remote-Sensing and Seismic Data

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Tenzer, Robert; Chen, Wenjin; Baranov, Alexey; Bagherbandi, Mohammad

2018-02-01

Remote-sensing data from altimetry and gravity satellite missions combined with seismic information have been used to investigate the Earth's interior, particularly focusing on the lithospheric structure. In this study, we use the subglacial bedrock relief BEDMAP2, the global gravitational model GOCO05S, and the ETOPO1 topographic/bathymetric data, together with a newly developed (continental-scale) seismic crustal model for Antarctica to compile the free-air, Bouguer, and mantle gravity maps over this continent and surrounding oceanic areas. We then use these gravity maps to interpret the Antarctic crustal and uppermost mantle structure. We demonstrate that most of the gravity features seen in gravity maps could be explained by known lithospheric structures. The Bouguer gravity map reveals a contrast between the oceanic and continental crust which marks the extension of the Antarctic continental margins. The isostatic signature in this gravity map confirms deep and compact orogenic roots under the Gamburtsev Subglacial Mountains and more complex orogenic structures under Dronning Maud Land in East Antarctica. Whereas the Bouguer gravity map exhibits features which are closely spatially correlated with the crustal thickness, the mantle gravity map reveals mainly the gravitational signature of the uppermost mantle, which is superposed over a weaker (long-wavelength) signature of density heterogeneities distributed deeper in the mantle. In contrast to a relatively complex and segmented uppermost mantle structure of West Antarctica, the mantle gravity map confirmed a more uniform structure of the East Antarctic Craton. The most pronounced features in this gravity map are divergent tectonic margins along mid-oceanic ridges and continental rifts. Gravity lows at these locations indicate that a broad region of the West Antarctic Rift System continuously extends between the Atlantic-Indian and Pacific-Antarctic mid-oceanic ridges and it is possibly formed by two major

ARM West Antarctic Radiation Experiment (AWARE) Field Campaign Report

Energy Technology Data Exchange (ETDEWEB)

Lubin, Daniel [Univ. of California, San Diego, CA (United States). Scripps Inst. of Oceanography; Bromwich, David H [Ohio State University; Vogelmann, Andrew M [Brookhaven National Lab. (BNL), Upton, NY (United States); Verlinde, Johannes [Pennsylvania State Univ., University Park, PA (United States); Russell, Lynn M [Univ. of California, San Diego, CA (United States). Scripps Inst. of Oceanography

2017-09-15

The U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) West Antarctic Radiation Experiment (AWARE) is the most technologically advanced atmospheric and climate science campaign yet fielded in Antarctica. AWARE was motivated be recent concern about the impact of cryospheric mass loss on global sea level rise. Specifically, the West Antarctic Ice Sheet (WAIS) is now the second largest contributor to rising sea level, after the Greenland Ice Sheet. As steadily warming ocean water erodes the grounding lines of WAIS components where they meet the Amundsen and Bellingshausen Seas, the retreating grounding lines moving inland and downslope on the underlying terrain imply mechanical instability of the entire WAIS. There is evidence that this point of instability may have already been reached, perhaps signifying more rapid loss of WAIS ice mass. At the same time, the mechanical support provided by adjacent ice shelves, and also the fundamental stability of exposed ice cliffs at the ice sheet grounding lines, will be adversely impacted by a warming atmosphere that causes more frequent episodes of surface melting. The surface meltwater damages the ice shelves and ice cliffs through hydrofracturing. With the increasing concern regarding these rapid cryospheric changes, AWARE was motivated by the need to (a) diagnose the surface energy balance in West Antarctica as related to both summer season climatology and potential surface melting, and (b) improve global climate model (GCM) performance over Antarctica, such that future cryospheric projections can be more reliable.

Developmental intervals during the larval and juvenile stages of the Antarctic myctophid fish Electrona antarctica in relation to changes in feeding and swimming functions

Science.gov (United States)

Moteki, Masato; Tsujimura, Eri; Hulley, Percy-Alexander

2017-06-01

The Antarctic myctophid fish species Electrona antarctica is believed to play a key role in the Southern Ocean food web, but there have been few studies on its early life history. This study examined the developmental changes in the external morphology and osteology of E. antarctica from the early larva to juvenile stages through the transformation phase and inferred changes in its behaviour and feeding mode. Once the larvae reached 12-13 mm body length (BL), they adopted a primordial suction feeding mode along with the acquisition of early swimming capabilities. Thereafter, both swimming and feeding functions were enhanced through fin development and ossification and acquisition of elements of the jaw and suspensorium. These processes indicate that larvae transition from the planktonic to nektonic phase upon reaching 12-13 mm BL when they enhance their both swimming and feeding abilities with growth. Transformation occurred when larvae reached 19-21 mm BL with changes such as discontinuous increases in eye diameter and upper jaw length and the appearance of photophores and dense body pigmentation. Osteological development of swimming- and feeding-related structures were mostly complete after transformation. Rapid changes in external morphology and osteology during the transformation stage are most likely related to ontogenetic vertical migration into deep waters.

Antarctic new particle formation from continental biogenic precursors

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E.-M. Kyrö

2013-04-01

Full Text Available Over Antarctica, aerosol particles originate almost entirely from marine areas, with minor contribution from long-range transported dust or anthropogenic material. The Antarctic continent itself, unlike all other continental areas, has been thought to be practically free of aerosol sources. Here we present evidence of local aerosol production associated with melt-water ponds in continental Antarctica. We show that in air masses passing such ponds, new aerosol particles are efficiently formed and these particles grow up to sizes where they may act as cloud condensation nuclei (CCN. The precursor vapours responsible for aerosol formation and growth originate very likely from highly abundant cyanobacteria Nostoc commune (Vaucher communities of local ponds. This is the first time freshwater vegetation has been identified as an aerosol precursor source. The influence of the new source on clouds and climate may increase in future Antarctica, and possibly elsewhere undergoing accelerating summer melting of semi-permanent snow cover.

Antarctic new particle formation from continental biogenic precursors

Science.gov (United States)

Kyrö, E.-M.; Kerminen, V.-M.; Virkkula, A.; Dal Maso, M.; Parshintsev, J.; Ruíz-Jimenez, J.; Forsström, L.; Manninen, H. E.; Riekkola, M.-L.; Heinonen, P.; Kulmala, M.

2013-04-01

Over Antarctica, aerosol particles originate almost entirely from marine areas, with minor contribution from long-range transported dust or anthropogenic material. The Antarctic continent itself, unlike all other continental areas, has been thought to be practically free of aerosol sources. Here we present evidence of local aerosol production associated with melt-water ponds in continental Antarctica. We show that in air masses passing such ponds, new aerosol particles are efficiently formed and these particles grow up to sizes where they may act as cloud condensation nuclei (CCN). The precursor vapours responsible for aerosol formation and growth originate very likely from highly abundant cyanobacteria Nostoc commune (Vaucher) communities of local ponds. This is the first time freshwater vegetation has been identified as an aerosol precursor source. The influence of the new source on clouds and climate may increase in future Antarctica, and possibly elsewhere undergoing accelerating summer melting of semi-permanent snow cover.

Revision of Eocene Antarctic carpet sharks (Elasmobranchii, Orectolobiformes) from Seymour Island, Antarctic Peninsula.

Science.gov (United States)

Engelbrecht, Andrea; Mörs, Thomas; Reguero, Marcelo A; Kriwet, Jürgen

2017-01-01

Seymour Island, Antarctic Peninsula, was once called the 'Rosetta Stone' of Southern Hemisphere palaeobiology, because this small island provides the most complete and richly fossiliferous Palaeogene sequence in Antarctica. Among fossil marine vertebrate remains, chondrichthyans seemingly were dominant elements in the Eocene Antarctic fish fauna. The fossiliferous sediments on Seymour Island are from the La Meseta Formation, which was originally divided into seven stratigraphical levels, TELMs 1-7 (acronym for Tertiary Eocene La Meseta) ranging from the upper Ypresian (early Eocene) to the late Priabonian (late Eocene). Bulk sampling of unconsolidated sediments from TELMs 5 and 6, which are Ypresian (early Eocene) and Lutetian (middle Eocene) in age, respectively, yielded very rich and diverse chondrichthyan assemblages including over 40 teeth of carpet sharks representing two new taxa, Notoramphoscyllium woodwardi gen. et sp. nov. and Ceolometlaouia pannucae gen. et sp. nov. Two additional teeth from TELM 5 represent two different taxa that cannot be assigned to any specific taxon and thus are left in open nomenclature. The new material not only increases the diversity of Eocene Antarctic selachian faunas but also allows two previous orectolobiform records to be re-evaluated. Accordingly, Stegostoma cf. faciatum is synonymized with Notoramphoscyllium woodwardi gen. et sp. nov., whereas Pseudoginglymostoma cf. brevicaudatum represents a nomen dubium . The two new taxa, and probably the additional two unidentified taxa, are interpreted as permanent residents, which most likely were endemic to Antarctic waters during the Eocene and adapted to shallow and estuarine environments.

On the origin and evolution of Antarctic Peracarida (Crustacea, Malacostraca

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Angelika Brandt

1999-12-01

Full Text Available The early separation of Gondwana and the subsequent isolation of Antarctica caused a long evolutionary history of its fauna. Both, long environmental stability over millions of years and habitat heterogeneity, due to an abundance of sessile suspension feeders on the continental shelf, favoured evolutionary processes of preadapted taxa, like for example the Peracarida. This taxon performs brood protection and this might be one of the most important reasons why it is very successful (i.e. abundant and diverse in most terrestrial and aquatic environments, with some species even occupying deserts. The extinction of many decapod crustaceans in the Cenozoic might have allowed the Peracarida to find and use free ecological niches. Therefore the palaeogeographic, palaeoclimatologic, and palaeo-hydrographic changes since the Palaeocene (at least since about 60 Ma ago and the evolutionary success of some peracarid taxa (e.g. Amphipoda, Isopoda led to the evolution of many endemic species in the Antarctic. Based on a phylogenetic analysis of the Antarctic Tanaidacea, Sieg (1988 demonstrated that the tanaid fauna of the Antarctic is mainly represented by phylogenetically younger taxa, and data from other crustacean taxa led Sieg (1988 to conclude that the recent Antarctic crustacean fauna must be comparatively young. His arguments are scrutinized on the basis of more recent data on the phylogeny and biodiversity of crustacean taxa, namely the Ostracoda, Decapoda, Mysidacea, Cumacea, Amphipoda, and Isopoda. This analysis demonstrates that the origin of the Antarctic fauna probably has different roots: an adaptive radiation of descendants from old Gondwanian ancestors was hypothesized for the isopod families Serolidae and Arcturidae, an evolution and radiation of phylogenetically old taxa in Antarctica could also be shown for the Ostracoda and the amphipod family Iphimediidae. A recolonization via the Scotia Arc appears possible for some species, though it is

A 50-year record of platinum, iridium, and rhodium in Antarctic snow: volcanic and anthropogenic sources.

Science.gov (United States)

Soyol-Erdene, Tseren-Ochir; Huh, Youngsook; Hong, Sungmin; Hur, Soon Do

2011-07-15

Antarctic snow preserves an atmospheric archive that enables the study of global atmospheric changes and anthropogenic disturbances from the past. We report atmospheric deposition rates of platinum group elements (PGEs) in Antarctica during the last ∼ 50 years based on determinations of Pt, Ir, and Rh in snow samples collected from Queen Maud Land, East Antarctica to evaluate changes in the global atmospheric budget of these noble metals. The 50-year average PGE concentrations in Antarctic snow were 17 fg g(-1) (4.7-76 fg g(-1)) for Pt, 0.12 fg g(-1) (pollution for Pt and probably for Rh since the 1980s, which may be attributed to the increasing emissions of these metals from anthropogenic sources such as automobile catalysts and metal production processes.

Toxicity of fuel-contaminated soil to Antarctic moss and terrestrial algae.

Science.gov (United States)

Nydahl, Anna C; King, Catherine K; Wasley, Jane; Jolley, Dianne F; Robinson, Sharon A

2015-09-01

Fuel pollution is a significant problem in Antarctica, especially in areas where human activities occur, such as at scientific research stations. Despite this, there is little information on the effects of petroleum hydrocarbons on Antarctic terrestrial biota. The authors demonstrate that the Antarctic mosses Bryum pseudotriquetrum, Schistidium antarctici, and Ceratodon purpureus, and the Antarctic terrestrial alga Prasiola crispa are relatively tolerant to Special Antarctic Blend (SAB) fuel-contaminated soil (measured as total petroleum hydrocarbons). Freshly spiked soils were more toxic to all species than were aged soils containing degraded fuel, as measured by photosynthetic efficiency (variable fluorescence/maximum fluorescence [Fv/Fm]), pigment content, and visual observations. Concentrations that caused 20% inhibition ranged from 16,600 mg/kg to 53,200 mg/kg for freshly spiked soils and from 30,100 mg/kg to 56,200 mg/kg for aged soils. The photosynthetic efficiency of C. purpureus and S. antarctici was significantly inhibited by exposure to freshly spiked soils with lowest-observed-effect concentrations of 27,900 mg/kg and 40,400 mg/kg, respectively. Prasiola crispa was the most sensitive species to freshly spiked soils (Fv/Fm lowest-observed-effect concentration 6700 mg/kg), whereas the Fv/Fm of B. pseudotriquetrum was unaffected by exposure to SAB fuel even at the highest concentration tested (62,900 mg/kg). Standard toxicity test methods developed for nonvascular plants can be used in future risk assessments, and sensitivity data will contribute to the development of remediation targets for petroleum hydrocarbons to guide remediation activities in Antarctica. © 2015 SETAC.

Precipitation Modeling over the Greenland and Antarctic Ice Sheets and the Relationship to the Surface Mass Balance and Climate

Science.gov (United States)

Bromwich, David H.; Chen, Qui-Shi

2005-01-01

Atmospheric numerical simulation and dynamic retrieval method with atmospheric numerical analyses are used to assess the spatial and temporal variability of Antarctic precipitation for the last two decades. First, the Polar MM5 has been run over Antarctica to study the Antarctic precipitation. With a horizontal resolution of 60km, the Polar MM5 has been run for the period of July 1996 through June 1999 in a series of short-term forecasts from initial and boundary conditions provided by the ECMWF operational analyses. In comparison with climatological maps, the major features of the spatial distribution of Antarctic precipitation are well captured by the Polar MM5. Drift snow effects on redistribution of surface accumulation over Antarctica are also assessed with surface wind fields from Polar MM5 in this study. There are complex divergence and convergence patterns of drift snow transport over Antarctica, especially along the coast. It is found that areas with large drift snow transport convergence and divergence are located around escarpment areas where there is large katabatic wind acceleration. In addition, areas with large snow transport divergence are generally accompanied by areas with large snow transport convergence nearby, indicating that drift snow transport is of local importance for the redistribution of the snowfall

Antarctic Ice-Sheet Mass Balance from Satellite Altimetry 1992 to 2001

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Zwally, H. Jay; Brenner, Anita C.; Cornejo, Helen; Giovinetto, Mario; Saba, Jack L.; Yi, Donghui

2003-01-01

A major uncertainty in understanding the causes of the current rate of sea level rise is the potential contributions from mass imbalances of the Greenland and Antarctic ice sheets. Estimates of the current mass balance of the Antarctic ice sheet are derived from surface- elevation changes obtained from 9 years of ERS - 1 & 2 radar altimeter data. Elevation time-series are created from altimeter crossovers among 90-day data periods on a 50 km grid to 81.5 S. The time series are fit with a multivariate linear/sinusoidal function to give the average rate of elevation change (dH/dt). On the major Rome-Filchner, Ross, and Amery ice shelves, the W d t are small or near zero. In contrast, the ice shelves of the Antarctic Peninsula and along the West Antarctic coast appear to be thinning significantly, with a 23 +/- 3 cm per year surface elevation decrease on the Larsen ice shelf and a 65 +/- 4 cm per year decrease on the Dotson ice shelf. On the grounded ice, significant elevation decreases are obtained over most of the drainage basins of the Pine Island and Thwaites glaciers in West Antarctica and inland of Law Dome in East Antarctica. Significant elevation increases are observed within about 200 km of the coast around much of the rest of the ice sheet. Farther inland, the changes are a mixed pattern of increases and decreases with increases of a few centimeters per year at the highest elevations of the East Antarctic plateau. The derived elevation changes are combined with estimates of the bedrock uplift from several models to provide maps of ice thickness change. The ice thickness changes enable estimates of the ice mass balances for the major drainage basins, the overall mass balance, and the current contribution of the ice sheet to global sea level change.

Perspective: Strategic challenges of tourism development and governance in Antarctica: taking stock and moving forward

NARCIS (Netherlands)

Lamers, M.A.J.; Liggett, D.; Amelung, B.

2012-01-01

Antarctic tourism has grown rapidly in volume and diversified into an ever wider range of activities, transport modes and destinations. Antarctica is a global commons, which limits the range of options for regulating tourism development. This configuration has raised concerns and debates among

Spirometry Changes in Cold Climatic Conditions of Antarctica.

Science.gov (United States)

Udaya, Iyamanda B; Laxmi, Chettangada C; Abhishekh, Hulegar A; Raju, Trichur R; Sathyaprabha, Talakad N

2015-01-01

Pulmonary function is one of the important physiological measures that is known to be affected during the changes in the altitude. There is dearth of literature on changes in the pulmonary function variables in the cold climate conditions of Antarctica. We carried out spirometry before, during and after one year stay at Antarctica in members of the Indian expedition. Spirometry was carried out on 23 members of the XXVI Indian Scientific Expedition to Antarctica at baseline, after six months of expedition and at the end of one year, using standard guidelines. The tests were carried out indoor in temperature controlled laboratory. The pulmonary function test parameters did not vary across the period. Although, both forced vital capacity (FVC) and forced expiratory volume in first second (FEV1) showed a decreasing trend but did not attain any statistical significance. However, peak expiratory flow (PEFR) rate was reduced significantly. Our study did not show consistently significant change in the pulmonary function parameters in the members of the Indian Antarctic expedition.

Morphological effects on the water balance of Antarctic foliose and fruticose lichens

NARCIS (Netherlands)

Huiskes, A.H.L.; Gremmen, N.J.M.; Francke, J.W.

1997-01-01

Uptake and loss of water by six lichen species from the Argentine Islands, Antarctic Peninsula, were studied in their natural habitat and in laboratory studies. Under field conditions, during a period of rain, uptake of moisture ranged from 15% d w h(-1) for Usnea antarctica to almost 90% for

Two Antarctic penguin genomes reveal insights into their evolutionary history and molecular changes related to the Antarctic environment.

Science.gov (United States)

Li, Cai; Zhang, Yong; Li, Jianwen; Kong, Lesheng; Hu, Haofu; Pan, Hailin; Xu, Luohao; Deng, Yuan; Li, Qiye; Jin, Lijun; Yu, Hao; Chen, Yan; Liu, Binghang; Yang, Linfeng; Liu, Shiping; Zhang, Yan; Lang, Yongshan; Xia, Jinquan; He, Weiming; Shi, Qiong; Subramanian, Sankar; Millar, Craig D; Meader, Stephen; Rands, Chris M; Fujita, Matthew K; Greenwold, Matthew J; Castoe, Todd A; Pollock, David D; Gu, Wanjun; Nam, Kiwoong; Ellegren, Hans; Ho, Simon Yw; Burt, David W; Ponting, Chris P; Jarvis, Erich D; Gilbert, M Thomas P; Yang, Huanming; Wang, Jian; Lambert, David M; Wang, Jun; Zhang, Guojie

2014-01-01

Penguins are flightless aquatic birds widely distributed in the Southern Hemisphere. The distinctive morphological and physiological features of penguins allow them to live an aquatic life, and some of them have successfully adapted to the hostile environments in Antarctica. To study the phylogenetic and population history of penguins and the molecular basis of their adaptations to Antarctica, we sequenced the genomes of the two Antarctic dwelling penguin species, the Adélie penguin [Pygoscelis adeliae] and emperor penguin [Aptenodytes forsteri]. Phylogenetic dating suggests that early penguins arose ~60 million years ago, coinciding with a period of global warming. Analysis of effective population sizes reveals that the two penguin species experienced population expansions from ~1 million years ago to ~100 thousand years ago, but responded differently to the climatic cooling of the last glacial period. Comparative genomic analyses with other available avian genomes identified molecular changes in genes related to epidermal structure, phototransduction, lipid metabolism, and forelimb morphology. Our sequencing and initial analyses of the first two penguin genomes provide insights into the timing of penguin origin, fluctuations in effective population sizes of the two penguin species over the past 10 million years, and the potential associations between these biological patterns and global climate change. The molecular changes compared with other avian genomes reflect both shared and diverse adaptations of the two penguin species to the Antarctic environment.

Glacier extent in sub-Antarctic Kerguelen archipelago from MIS 3 period: Evidence from 36Cl dating

Science.gov (United States)

Jomelli, Vincent; Schimmelpfennig, Irene; Favier, Vincent; Mokadem, Fatima; Landais, Amaelle; Rinterknecht, Vincent; Brunstein, Daniel; Verfaillie, Deborah; Legentil, Claude; Aumaitre, Georges; Bourlès, Didier L.; Keddadouche, Karim

2018-03-01

Documenting sub-Antarctic glacier variations during the local last glacial maximum is of major interest to better understand their sensitivity to atmospheric and oceanic temperature changes in conjunction with Antarctic ice sheet changes. However, data are sparse because evidence of earlier glacier extents is for most sub-Antarctic islands located offshore making their observation complex. Here, we present 22 cosmogenic 36Cl surface exposure ages obtained from five sites at Kerguelen to document the glacial history. The 36Cl ages from roche moutonnee surfaces, erratics and boulders collected on moraines span from 41.9 ± 4.4 ka to 14.3 ± 1.1 ka. Ice began to retreat on the eastern part of the main island before 41.4 ± 4.4 ka. Slow deglaciation occurred from ∼41 to ∼29 ka. There is no evidence of advances between 29 ka and the Antarctic Cold Reversal (ACR) period (∼14.5-12.9 ka) period. During the ACR, however, the Bontemps and possibly Belvedere moraines were formed by the advance of a Cook Ice Cap outlet glacier and a local glacier on the Presque Ile Jeanne d'Arc, respectively. This glacier evolution differs partly from that of glaciers in New Zealand and in Patagonia. These asynchronous glacier changes in the sub-Antarctic region are however in agreement with sea surface temperature changes recorded around Antarctica, which suggest differences in the climate evolution of the Indo-Pacific and Atlantic sectors of Antarctica.

PROFILE: Environmental Impact Assessment Under the National Environmental Policy Act and the Protocol on Environmental Protection to the Antarctic Treaty.

Science.gov (United States)

Ensminger; McCold; Webb

1999-07-01

/ Antarctica has been set aside by the international community for protection as a natural reserve and a place for scientific research. Through the Antarctic Treaty of 1961, the signing nations agreed to cooperate in protecting the antarctic environment, in conducting scientific studies, and in abstaining from the exercise of territorial claims. The 1991 signing of the Protocol on Environmental Protection to the Antarctic Treaty (Protocol) by representatives of the 26 nations comprising the Antarctic Treaty Consultative Parties (Parties) significantly strengthened environmental protection measures for the continent. The Protocol required ratification by each of the governments individually prior to official implementation. The US government ratified the Protocol by passage of the Antarctic Science, Tourism, and Conservation Act of 1997. Japan completed the process by ratifying the Protocol on December 15, 1997. US government actions undertaken in Antarctica are subject to the requirements of both the Protocol and the US National Environmental Policy Act (NEPA). There are differences in the scope and intent of the Protocol and NEPA; however, both require environmental impact assessment (EIA) as part of the planning process for proposed actions that have the potential for environmental impacts. In this paper we describe the two instruments and highlight key similarities and differences with particular attention to EIA. Through this comparison of the EIA requirements of NEPA and the Protocol, we show how the requirements of each can be used in concert to provide enhanced environmental protection for the antarctic environment. NEPA applies only to actions of the US government; therefore, because NEPA includes certain desirable attributes that have been refined and clarified through numerous court cases, and because the Protocol is just entering implementation internationally, some recommendations are made for strengthening the procedural requirements of the Protocol

A new albedo parameterization for use in climate models over the Antarctic ice sheet

NARCIS (Netherlands)

Kuipers Munneke, P.|info:eu-repo/dai/nl/304831891; van den Broeke, M.R.|info:eu-repo/dai/nl/073765643; Lenaerts, J.T.M.|info:eu-repo/dai/nl/314850163; Flanner, M.G.; Gardner, A.S.; van de Berg, W.J.|info:eu-repo/dai/nl/304831611

2011-01-01

A parameterization for broadband snow surface albedo, based on snow grain size evolution, cloud optical thickness, and solar zenith angle, is implemented into a regional climate model for Antarctica and validated against field observations of albedo for the period 1995–2004. Over the Antarctic

Generation of terrestrial radiation database in the Larsemann Hills, Antarctica

International Nuclear Information System (INIS)

Pal, Rupali; Dhabekar, Bhushan; Jose, Jis Romal; Chinnaesakki, S.; Bakshi, A.K.; Datta, D.; Pradeepkumar, K.S.

2018-01-01

Natural background radiation in the environment includes terrestrial radiation, cosmic radiation from space and air activity due to radon/thoron. It is known that cosmic contribution increases near the poles. The terrestrial component is largely due to 232 Th and 238 U series and 40 K. BARC under the cosmic ray dosimetry project with National Centre for Antarctic and Ocean Research (NCAOR) has taken up measurement of natural background radiation at Larsemann Hills, Antarctica. The project includes generation of baseline data on terrestrial radioactivity in water, soil and rock and estimation of cosmic ray doses. Extensive radiation surveys were carried out by the BARC team in the 35 th and 36 th expedition in and around Larsemann hills in East Antarctica where the third Indian station 'Bharati' is situated. This paper presents mapping of terrestrial radiation levels in Antarctica which will help in strengthening the background radiation database and develop a Radiation Informatics System (RIS)

Strategic Thinking for the Antarctic Environment: The Use of Assessment Tools in Governance

NARCIS (Netherlands)

Lamers, M.A.J.; Liggett, D.; Tin, T.

2014-01-01

The Antarctic Treaty System has established the strategic vision of Antarctica as a natural reserve, set aside for peace and science in the interest of all of humankind. However, the strategic focus that is implied by the notion of a stable, long-term institutional arrangement is not reflected in

Velocities of antarctic outlet glaciers determined from sequential Landsat images

Science.gov (United States)

MacDonald, Thomas R.; Ferrigno, Jane G.; Williams, Richard S.; Lucchitta, Baerbel K.

1989-01-01

Approximately 91.0 percent of the volume of present-day glacier ice on Earth is in Antarctica; Greenland contains about another 8.3 percent of the volume. Thus, together, these two great ice sheets account for an estimated 99.3 percent of the total. Long-term changes in the volume of glacier ice on our planet are the result of global climate change. Because of the relationship of global ice volume to sea level (± 330 cubic kilometers of glacier ice equals ± 1 millimeter sea level), changes in the mass balance of the antarctic ice sheet are of particular importance.Whether the mass balance of the east and west antarctic ice sheets is positive or negative is not known. Estimates of mass input by total annual precipitation for the continent have been made from scattered meteorological observations (Swithinbank 1985). The magnitude of annual ablation of the ice sheet from calving of outlet glaciers and ice shelves is also not well known. Although the velocities of outlet glaciers can be determined from field measurements during the austral summer,the technique is costly, does not cover a complete annual cycle,and has been applied to just a few glaciers. To increase the number of outlet glaciers in Antarctica for which velocities have been determined and to provide additional data for under-standing the dynamics of the antarctic ice sheets and their response to global climate change, sequential Landsat image of several outlet glaciers were measured.

Coastal-change and glaciological map of the Trinity Peninsula area and south Shetland Islands, Antarctica: 1843-2001: Chapter A in Coastal-change and glaciological maps of Antarctica

Science.gov (United States)

Ferrigno, Jane G.; Cook, Alison J.; Foley, Kevin M.; Williams, Richard S.; Swithinbank, Charles; Fox, Adrian J.; Thomson, Janet W.; Sievers, Jorn

2006-01-01

Foundation's (1990) Division of Polar Programs. On the basis of these recommendations, the U.S. Geological Survey (USGS) decided that the archive of early 1970s Landsat 1, 2, and 3 Multispectral Scanner (MSS) images of Antarctica and the subsequent repeat coverage made possible with Landsat and other satellite images provided an excellent means of documenting changes in the coastline of Antarctica (Ferrigno and Gould, 1987). The availability of this information provided the impetus for carrying out a comprehensive analysis of the glaciological features of the coastal regions and changes in ice fronts of Antarctica (Swithinbank, 1988; Williams and Ferrigno, 1988). The project was later modified to include Landsat 4 and 5 MSS and Thematic Mapper (TM) [and in some areas Landsat 7 Enhanced Thematic Mapper Plus (ETM+)], RADARSAT images, and other data where available, to compare changes that occurred during a 20- to 25- or 30-year time interval (or longer where data were available, as in the Antarctic Peninsula). The results of the analysis are being used to produce a digital database and a series of USGS Geologic Investigations Series Maps (I–2600) consisting of 23 maps at 1:1,000,000 scale and 1 map at 1:5,000,000 scale, in both paper and digital format (Williams and others, 1995; Williams and Ferrigno, 1998; Ferrigno and others, 2002).

East Antarctic rifting triggers uplift of the Gamburtsev Mountains

Science.gov (United States)

Ferraccioli, F.; Finn, Carol A.; Jordan, Tom A.; Bell, Robin E.; Anderson, Lester M.; Damaske, Detlef

2011-01-01

The Gamburtsev Subglacial Mountains are the least understood tectonic feature on Earth, because they are completely hidden beneath the East Antarctic Ice Sheet. Their high elevation and youthful Alpine topography, combined with their location on the East Antarctic craton, creates a paradox that has puzzled researchers since the mountains were discovered in 1958. The preservation of Alpine topography in the Gamburtsevs may reflect extremely low long-term erosion rates beneath the ice sheet, but the mountains’ origin remains problematic. Here we present the first comprehensive view of the crustal architecture and uplift mechanisms for the Gamburtsevs, derived from radar, gravity and magnetic data. The geophysical data define a 2,500-km-long rift system in East Antarctica surrounding the Gamburtsevs, and a thick crustal root beneath the range. We propose that the root formed during the Proterozoic assembly of interior East Antarctica (possibly about 1 Gyr ago), was preserved as in some old orogens and was rejuvenated during much later Permian (roughly 250 Myr ago) and Cretaceous (roughly 100 Myr ago) rifting. Much like East Africa, the interior of East Antarctica is a mosaic of Precambrian provinces affected by rifting processes. Our models show that the combination of rift-flank uplift, root buoyancy and the isostatic response to fluvial and glacial erosion explains the high elevation and relief of the Gamburtsevs. The evolution of the Gamburtsevs demonstrates that rifting and preserved orogenic roots can produce broad regions of high topography in continental interiors without significantly modifying the underlying Precambrian lithosphere.

Evaluation of DNA dosimetry to assess ozone-mediated variability of biologically harmful radiation in Antarctica

NARCIS (Netherlands)

George, AL; Peat, HJ; Buma, AGJ

In this study we investigated the use of a DNA dosimeter to accurately measure changes in ultraviolet B radiation (UVBR; 280-315 nm) under Antarctic ozone hole conditions. Naked DNA solution in quartz tubes was exposed to ambient solar radiation at Rothera Research Station, Antarctica, between

PERSPECTIVE How committed are we to monitoring human impacts in Antarctica?

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Hughes, Kevin A.

2010-12-01

Under the Antarctic Treaty System, environmental monitoring is a legal obligation for signatory nations and an essential tool for managers attempting to minimize local human impacts, but is it given the importance it merits? Antarctica is a vast frozen continent with an area around 1.5 times that of Europe (14 000 000 km2), but the majority of its terrestrial life is found on multiple outcrops or 'islands' of ice-free coastal ground, with a combined area of ~6000 km2, equivalent to four times that of Greater London (Tin et al 2009). The biological communities of these ice-free terrestrial habitats are dominated by a small number of biological groups, primarily mosses, lichens, microinvertebrates and microorganisms. They include many endemic species, while birds and marine mammals use coastal areas as breeding sites (Chown and Convey 2007). Figure 1 Figure 1. Map of the Antarctic Treaty area (south of latitude 60°S) showing the locations of year-round and seasonal stations built on rock or permanent ice (i.e. ice sheets or ice shelves). Data on station locations were taken from the Council of Managers of National Antarctic Programs website (COMNAP 2010). There is evidence to suggest that although these stations are registered on the COMNAP list, a number of stations are not regularly occupied or in use (see United Kingdom et al 2006, p 9). Since the influx of national scientific research programmes and infrastructure that accompanied the International Geophysical Year (1957-1958), Antarctica's habitats have been encroached upon increasingly by human activities. Over 120 research stations have been built (~75 currently operational) with the great majority located on ice-free coastal ground to allow ease of access by ship. (Headland 2009, COMNAP 2010). Construction of cargo and personnel landing and handling facilities, station buildings, airport infrastructure, roads and fuel storage areas have, to varying degrees, destroyed native vegetation and terrestrial fauna

Stable isotopes and Antarctic moss banks: Plants and soil microbes respond to recent warming on the Antarctic Peninsula

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Royles, Jessica; Amesbury, Matthew; Ogée, Jérôme; Wingate, Lisa; Convey, Peter; Hodgson, Dominic; Griffiths, Howard; Leng, Melanie; Charman, Dan

2014-05-01

The Antarctic Peninsula is one of the most rapidly warming regions on Earth, with air temperature increases of as much as 3°C recorded since the 1950s. However, the longer-term context of this change is limited and existing records, largely relying on ice core data, are not suitably located to be able to trace the spatial signature of change over time. We are working on a project exploiting stable isotope records preserved in moss peat banks spanning 10 degrees of latitude along the Antarctic Peninsula as an archive of late Holocene climate variability. Here we present a unique time series of past moss growth and soil microbial activity that has been produced from a 150 year old moss bank at Lazarev Bay, Alexander Island (69°S), a site at the southern limit of significant plant growth in the Antarctic Peninsula region. These moss banks are ideal archives for palaeoclimate research as they are well-preserved by freezing, generally monospecific, easily dated by radiocarbon techniques, and have sufficiently high accumulation rates to permit decadal resolution. We use accumulation rates, cellulose δ13C and fossil testate amoebae to show that growth rates, assimilation and microbial productivity rose rapidly in the 1960s, consistent with temperature change, although recently may have stalled, concurrent with other evidence. The increase in biological activity is unprecedented in the last 150 years. Along with work completed on Signy Island (60°S), in the South Orkney Islands, in which we used carbon isotope evidence to show recent climate-related enhancement of CO2 assimilation and peat accumulation rates in Antarctica, the observed relationships between moss growth, microbial activity and climate suggests that moss bank records have the potential to test the regional expression of temperature variability shown by instrumental data on the Antarctic Peninsula over centennial to millennial timescales, by providing long-term records of summer growth conditions

Antarctic snow and global climate

International Nuclear Information System (INIS)

Granberg, H.B.

2001-01-01

Global circulation models (GCM) indicate that global warming will be most pronounced at polar regions and high latitudes, causing concern about the stability of the Antarctic ice cap. A project entitled the Seasonal Snow in Antarctica examined the properties of the near surface snow to determine the current conditions that influence snow cover development. The goal was to assess the response of the snow cover in Queen Maud Land (QML) to an increased atmospheric carbon dioxide content. The Antarctic snow cover in QML was examined as part of the FINNARP expeditions in 1999 and 2000 which examined the processes that influence the snow cover. Its energy and mass balance were also assessed by examining the near surface snow strata in shallow (1-2 m) pits and by taking measurements of environmental variables. This made it possible to determine if the glacier is in danger of melting at this northerly location in the Antarctic. The study also made it possible to determine which variables need to change and by how much, for significant melting to occur. It was shown that the Antarctic anticyclone creates particular conditions that protect the snow cover from melting. The anticyclone brings dry air from the stratosphere during most of the year and is exempt from the water vapour feedback. It was concluded that even a doubling of atmospheric carbon dioxide will not produce major snow melt runoff. 8 refs

Mollusc shells as archival indicators of metal contamination in the Australian antarctic marine environment

International Nuclear Information System (INIS)

Simpson, R.D.

2000-01-01

Full text: Although considered by many to be a pristine environment past activities in Antarctica have caused localised contamination. In particular, the practice of disposing of station waste in open tips adjacent to the seashore has caused heavy metals to migrate to the marine environment. Times have changed and these practices are no longer permitted. Under international agreements, such as the Protocol on Environmental Protection to the Antarctic Treaty System, operators are now required to clean-up these sites so long as the act of clean-up does not cause greater environmental harm than leaving them where they are. The Australian Antarctic Division has embarked on a program to develop techniques for clean-up and remediation of disused waste disposal sites and is also developing techniques for monitoring the environment to ensure that clean-up does not cause greater environmental harm. The Antarctic clam, Laternula elliptica, is common in near shore sediments around the entire coast of Antarctica. It is a filter feeder that extracts suspended sediments from the water column and has been suggested as a candidate for mussel watch-type monitoring in Antarctica. Contaminants in waste disposal tips in Antarctica are likely to be mobilised in pulses caused by the seasonal flush of melting snow as it passes through the contaminated material. As a filter feeder Laternula will be exposed to the highest concentrations of contaminants while they remain in suspension. If contaminants are sequestered into the shells of the bivalve and if their levels in the shell can be analysed in relation to the annual growth rings then they may prove to be a useful archive of past environmental contamination. Specimens of Laternula were exposed to known concentrations of copper and cadmium under aquarium conditions in Antarctica to understand accumulation and depuration rates in the soft tissues. This information is used to assist interpretation of concentrations in animals collected

Plant and Bird Presence Strongly Influences the Microbial Communities in Soils of Admiralty Bay, Maritime Antarctica

Science.gov (United States)

Teixeira, Lia C. R. S.; Yeargeau, Etienne; Balieiro, Fabiano C.; Piccolo, Marisa C.; Peixoto, Raquel S.; Greer, Charles W.; Rosado, Alexandre S.

2013-01-01

Understanding the environmental factors that shape microbial communities is crucial, especially in extreme environments, like Antarctica. Two main forces were reported to influence Antarctic soil microbes: birds and plants. Both birds and plants are currently undergoing relatively large changes in their distribution and abundance due to global warming. However, we need to clearly understand the relationship between plants, birds and soil microorganisms. We therefore collected rhizosphere and bulk soils from six different sampling sites subjected to different levels of bird influence and colonized by Colobanthus quitensis and Deschampsia antarctica in Admiralty Bay, King George Island, Maritime Antarctic. Microarray and qPCR assays targeting 16S rRNA genes of specific taxa were used to assess microbial community structure, composition and abundance and analyzed with a range of soil physico-chemical parameters. The results indicated significant rhizosphere effects in four out of the six sites, including areas with different levels of bird influence. Acidobacteria were significantly more abundant in soils with little bird influence (low nitrogen) and in bulk soil. In contrast, Actinobacteria were significantly more abundant in the rhizosphere of both plant species. At two of the sampling sites under strong bird influence (penguin colonies), Firmicutes were significantly more abundant in D. antarctica rhizosphere but not in C. quitensis rhizosphere. The Firmicutes were also positively and significantly correlated to the nitrogen concentrations in the soil. We conclude that the microbial communities in Antarctic soils are driven both by bird and plants, and that the effect is taxa-specific. PMID:23840411

Plant and bird presence strongly influences the microbial communities in soils of Admiralty Bay, Maritime Antarctica.

Science.gov (United States)

Teixeira, Lia C R S; Yeargeau, Etienne; Balieiro, Fabiano C; Piccolo, Marisa C; Peixoto, Raquel S; Greer, Charles W; Rosado, Alexandre S

2013-01-01

Understanding the environmental factors that shape microbial communities is crucial, especially in extreme environments, like Antarctica. Two main forces were reported to influence Antarctic soil microbes: birds and plants. Both birds and plants are currently undergoing relatively large changes in their distribution and abundance due to global warming. However, we need to clearly understand the relationship between plants, birds and soil microorganisms. We therefore collected rhizosphere and bulk soils from six different sampling sites subjected to different levels of bird influence and colonized by Colobanthus quitensis and Deschampsia antarctica in Admiralty Bay, King George Island, Maritime Antarctic. Microarray and qPCR assays targeting 16S rRNA genes of specific taxa were used to assess microbial community structure, composition and abundance and analyzed with a range of soil physico-chemical parameters. The results indicated significant rhizosphere effects in four out of the six sites, including areas with different levels of bird influence. Acidobacteria were significantly more abundant in soils with little bird influence (low nitrogen) and in bulk soil. In contrast, Actinobacteria were significantly more abundant in the rhizosphere of both plant species. At two of the sampling sites under strong bird influence (penguin colonies), Firmicutes were significantly more abundant in D. antarctica rhizosphere but not in C. quitensis rhizosphere. The Firmicutes were also positively and significantly correlated to the nitrogen concentrations in the soil. We conclude that the microbial communities in Antarctic soils are driven both by bird and plants, and that the effect is taxa-specific.

Plant and bird presence strongly influences the microbial communities in soils of Admiralty Bay, Maritime Antarctica.

Directory of Open Access Journals (Sweden)

Lia C R S Teixeira

Full Text Available Understanding the environmental factors that shape microbial communities is crucial, especially in extreme environments, like Antarctica. Two main forces were reported to influence Antarctic soil microbes: birds and plants. Both birds and plants are currently undergoing relatively large changes in their distribution and abundance due to global warming. However, we need to clearly understand the relationship between plants, birds and soil microorganisms. We therefore collected rhizosphere and bulk soils from six different sampling sites subjected to different levels of bird influence and colonized by Colobanthus quitensis and Deschampsia antarctica in Admiralty Bay, King George Island, Maritime Antarctic. Microarray and qPCR assays targeting 16S rRNA genes of specific taxa were used to assess microbial community structure, composition and abundance and analyzed with a range of soil physico-chemical parameters. The results indicated significant rhizosphere effects in four out of the six sites, including areas with different levels of bird influence. Acidobacteria were significantly more abundant in soils with little bird influence (low nitrogen and in bulk soil. In contrast, Actinobacteria were significantly more abundant in the rhizosphere of both plant species. At two of the sampling sites under strong bird influence (penguin colonies, Firmicutes were significantly more abundant in D. antarctica rhizosphere but not in C. quitensis rhizosphere. The Firmicutes were also positively and significantly correlated to the nitrogen concentrations in the soil. We conclude that the microbial communities in Antarctic soils are driven both by bird and plants, and that the effect is taxa-specific.

Using Gravity Inversion to Estimate Antarctic Geothermal Heat Flux

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Vaughan, Alan P. M.; Kusznir, Nick J.; Ferraccioli, Fausto; Leat, Phil T.; Jordan, Tom A. R. M.; Purucker, Michael E.; (Sasha) Golynsky, A. V.; Rogozhina, Irina

2014-05-01

New modelling studies for Greenland have recently underlined the importance of GHF for long-term ice sheet behaviour (Petrunin et al. 2013). Revised determinations of top basement heat-flow for Antarctica and adjacent rifted continental margins using gravity inversion mapping of crustal thickness and continental lithosphere thinning (Chappell & Kusznir 2008), using BedMap2 data have provided improved estimates of geothermal heat flux (GHF) in Antarctica where it is very poorly known. Continental lithosphere thinning and post-breakup residual thicknesses of continental crust determined from gravity inversion have been used to predict the preservation of continental crustal radiogenic heat productivity and the transient lithosphere heat-flow contribution within thermally equilibrating rifted continental and oceanic lithosphere. The sensitivity of present-day Antarctic top basement heat-flow to initial continental radiogenic heat productivity, continental rift and margin breakup age has been examined. Recognition of the East Antarctic Rift System (EARS), a major Permian to Cretaceous age rift system that appears to extend from the continental margin at the Lambert Rift to the South Pole region, a distance of 2500 km (Ferraccioli et al. 2011) and is comparable in scale to the well-studied East African rift system, highlights that crustal variability in interior Antarctica is much greater than previously assumed. GHF is also important to understand proposed ice accretion at the base of the EAIS in the GSM and its links to sub-ice hydrology (Bell et al. 2011). References Bell, R.E., Ferraccioli, F., Creyts, T.T., Braaten, D., Corr, H., Das, I., Damaske, D., Frearson, N., Jordan, T., Rose, K., Studinger, M. & Wolovick, M. 2011. Widespread persistent thickening of the East Antarctic Ice Sheet by freezing from the base. Science, 331 (6024), 1592-1595. Chappell, A.R. & Kusznir, N.J. 2008. Three-dimensional gravity inversion for Moho depth at rifted continental margins

Unexpectedly high ultrafine aerosol concentrations above East Antarctic sea-ice

Science.gov (United States)

Humphries, R. S.; Klekociuk, A. R.; Schofield, R.; Keywood, M.; Ward, J.; Wilson, S. R.

2015-10-01

The effect of aerosols on clouds and their radiative properties is one of the largest uncertainties in our understanding of radiative forcing. A recent study has concluded that better characterisation of pristine, natural aerosol processes leads to the largest reduction in these uncertainties. Antarctica, being far from anthropogenic activities, is an ideal location for the study of natural aerosol processes. Aerosol measurements in Antarctica are often limited to boundary layer air-masses at spatially sparse coastal and continental research stations, with only a handful of studies in the sea ice region. In this paper, the first observational study of sub-micron aerosols in the East Antarctic sea ice region is presented. Measurements were conducted aboard the ice-breaker Aurora Australis in spring 2012 and found that boundary layer condensation nuclei (CN3) concentrations exhibited a five-fold increase moving across the Polar Front, with mean Polar Cell concentrations of 1130 cm-3 - higher than any observed elsewhere in the Antarctic and Southern Ocean region. The absence of evidence for aerosol growth suggested that nucleation was unlikely to be local. Air parcel trajectories indicated significant influence from the free troposphere above the Antarctic continent, implicating this as the likely nucleation region for surface aerosol, a similar conclusion to previous Antarctic aerosol studies. The highest aerosol concentrations were found to correlate with low pressure systems, suggesting that the passage of cyclones provided an accelerated pathway, delivering air-masses quickly from the free-troposphere to the surface. After descent from the Antarctic free troposphere, trajectories suggest that sea ice boundary layer air-masses travelled equator-ward into the low albedo Southern Ocean region, transporting with them emissions and these aerosol nuclei where, after growth, may potentially impact on the region's radiative balance. The high aerosol concentrations and

Upper Mantle Seismic Anisotropy Beneath West Antarctica from Shear Wave Splitting Analysis of POLENET/ANET Data

Science.gov (United States)

Accardo, N.; Wiens, D. A.; Hernandez, S.; Aster, R. C.; Nyblade, A.; Anandakrishnan, S.; Huerta, A. D.; Wilson, T. J.

2011-12-01

We constrain azimuthal anisotropy in the Antarctic upper mantle using shear wave splitting parameters obtained from teleseismic SKS, SKKS, and PKS phases recorded at 30 broad-band seismometers deployed in West Antarctica, and the Transantarctic Mountains as a part of POLENET/ANET. The first seismometers were deployed in late 2007 and additional seismometers were deployed in 2008 and 2009. The seismometers generally operate year-round using solar power, insulated boxes, and either rechargeable AGM or primary lithium batteries. We used an eigenvalue technique to linearize the rotated and shifted shear wave particle motions and determine the best splitting parameters. Robust windows around the individual phases were chosen using the Teanby cluster-analysis algorithm. We visually inspected all results and assigned a quality rating based on factors including signal-to-noise ratios, particle motions, and error contours. The best results for each station were then stacked to get an average splitting direction and delay time. The delay times range from 0.33 to 1.33 s, but generally average about 1 s. We conclude that the splitting results from anisotropy in the upper mantle, since the large splitting times cannot be accumulated in the relatively thin crust (20-30 km) of the region. Overall, fast directions in West Antarctica are at large angles to the direction of Antarctic absolute plate motion in either hotspot or no-net rotation frameworks, showing that the anisotropic fabric does not result from shear associated with the motion of Antarctica over the mantle. The West Antarctic fast directions are also much different than those found in East Antarctica by previous studies. We suggest that the East Antarctic splitting results from anisotropy frozen into the cold cratonic continental lithosphere, whereas West Antarctic splitting is related to Cenozoic tectonism. Stations within the West Antarctic Rift System (WARS), a region of Cenozoic extension, show fast directions

Broadband seismic deployments in East Antarctica: IPY contribution to monitoring the Earth’s interiors

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Masaki Kanao

2014-06-01

Full Text Available “Deployment of broadband seismic stations on the Antarctica continent” is an ambitious project to improve the spatial resolution of seismic data across the Antarctic Plate and surrounding regions. Several international collaborative programs for the purpose of geomonitoring were conducted in Antarctica during the International Polar Year (IPY 2007-2008. The Antarctica’s GAmburtsev Province (AGAP; IPY #147, the GAmburtsev Mountain SEISmic experiment (GAMSEIS, a part of AGAP, and the Polar Earth Observing Network (POLENET; IPY #185 were major contributions in establishing a geophysical network in Antarctica. The AGAP/GAMSEIS project was an internationally coordinated deployment of more than 30 broadband seismographs over the crest of the Gambursev Mountains (Dome-A, Dome-C and Dome-F area. The investigations provide detailed information on crustal thickness and mantle structure; provide key constraints on the origin of the Gamburtsev Mountains; and more broadly on the structure and evolution of the East Antarctic craton and subglacial environment. From GAMSEIS and POLENET data obtained, local and regional seismic signals associated with ice movements, oceanic loading, and local meteorological variations were recorded together with a significant number of teleseismic events. In this chapter, in addition to the Earth’s interiors, we will demonstrate some of the remarkable seismic signals detected during IPY that illustrate the capabilities of broadband seismometers to study the sub-glacial environment, particularly at the margins of Antarctica. Additionally, the AGAP and POLENET stations have an important role in the Federation of Digital Seismographic Network (FDSN in southern high latitude.

New aerogeophysical views of crustal architecture in the Recovery frontier of East Antarctica

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Ferraccioli, Fausto; Forsberg, Rene; Jordan, Tom; Matsuoka, Kenichi; Olsen, Arne; King, Owen; Ghidella, Marta

2014-05-01

East Antarctica is the least known continent on Earth, despite being regarded as a keystone in Gondwana, Rodinia and possibly Columbia supercontinents. Significant progress has however been made in recent years in the exploration of East Antarctica using airborne geophysical techniques. Spurred by the International Polar Year major collaborative aerogeophysical campaigns have been performed over the Wilkes Subglacial Basin, the Aurora Subglacial Basin and the Gamburtsev Subglacial Mountains. Analyses of these recent datasets is providing fundamental new glimpses into the crustal architecture in interior East Antarctica, as well as several new interpretations regarding its linkages with tectonic and geodynamic evolution from the Precambrian to the Mesozoic. Here we present the first results of a major reconnaissance aerogeophysical survey over the largely unexplored Recovery ice stream catchment in East Antarctica, flown during the IceGRAV 2012-13 field season, as part of a new international Danish, Norwegian, UK and Argentine collaboration. Over 29,000 line km of new radio-echo sounding, laser altimetry, gravity and magnetic data were acquired using a British Antarctic Survey Twin Otter. We will focus primarily on presenting the new potential field datasets and discuss the anomaly patterns seen in aeromagnetic anomaly maps, free air, Bouguer and isostatic residual maps. The aerogeophysical datasets we will present provide a new foundation to address a cascade of open questions regarding this part of East Antarctica, including: i) Where are and what is the nature of the major tectonic boundaries separating the Coast block, the Shackleton Range and the Dronning Maud Land crustal provinces? Specifically is there new geophysical evidence in support of a Pan-African age suture zone in the Shackleton Range linked to Gondwana assembly?; ii) is there evidence in support of an older Grenvillian-age orogenic belt, extending across the interior of East Antarctica?; Or, is

Coastal-change and glaciological map of the Ronne Ice Shelf area, Antarctica, 1974-2002

Science.gov (United States)

Ferrigno, Jane G.; Foley, K.M.; Swithinbank, C.; Williams, R.S.; Dalide, L.M.

2005-01-01

(MSS) images of Ant-arctica and the subsequent repeat coverage made possible with Landsat and other satellite images provided an excellent means of documenting changes in the coastline of Antarctica (Ferrigno and Gould, 1987). The availability of this information provided the impetus for carrying out a comprehensive analysis of the glaciological features of the coastal regions and changes in ice fronts of Antarctica (Swithinbank, 1988; Williams and Ferrigno, 1988). The project was later modified to include Landsat 4 and 5 MSS and Thematic Mapper (TM) (and in some areas Landsat 7 Enhanced Thematic Mapper Plus (ETM+)), RADARSAT images, and other data where available, to compare changes during a 20- to 25- or 30-year time interval (or longer where data were available, as in the Antarctic Peninsula). The results of the analysis are being used to produce a digital database and a series of USGS Geologic Investigations Series Maps (I-2600) consisting of 23 maps at 1:1,000,000 scale and 1 map at 1:5,000,000 scale, in both paper and digital format (Williams and others, 1995; Williams and Ferrigno, 1998; Ferrigno and others, 2002) (available online at http://www.glaciers.er.usgs.gov).

Spatial and Temporal Antarctic Ice Sheet Mass Trends, Glacio-Isostatic Adjustment, and Surface Processes from a Joint Inversion of Satellite Altimeter, Gravity, and GPS Data

Science.gov (United States)

Martin-Espanol, Alba; Zammit-Mangion, Andrew; Clarke, Peter J.; Flament, Thomas; Helm, Veit; King, Matt A.; Luthcke, Scott B.; Petrie, Elizabeth; Remy, Frederique; Schon, Nana;

ICE VELOCITY MEASUREMENT IN EAST ANTARCTICA FROM 1960s TO 1980s BASED ON ARGON AND LANDSAT IMAGERY

Directory of Open Access Journals (Sweden)

R. Li

2017-09-01

Full Text Available Ice flow velocity is a vital parameter for estimating the ice mass balance of glaciers in Antarctica. Especially long time serial observation of the surface velocity is of great significance to assessing the relationship between Antarctic ice materials and global climate change. However, the existing research on Antarctic ice velocity based on remote sensing data since 1970s due to the harsh climate in Antarctica. This paper presents an ice flow velocity estimating method includes image pre-processing, geometric model reconstruction, image ortho-rectification and feature matching by using ARGON images token in 1963 and Landsat images collected form 1973 to 1989.Considering the temporal-spatial distributions of ARGON images and Landsat images in Antarctica, two different methods respectively based on ortho-photos pair and Non-Ortho photos are adopted in this paper. More specifically, when there exist two stereo pairs taken in different time in the glacier region, after being ortho-rectified, the stereo pairs can be used to calculate ice flow velocity based on feature matching method. Otherwise, a parallax decomposition method that separates the effect of the terrain relief from the ice flow motion is applied when there only exists one stereo pair with a certain time interval. With this method, glacier surface velocity is available in the glacier region lacked enough stereo pairs. The methods mentioned above for estimating ice flow velocity are applied in Totten, Amery and Fimbul, etc. in eastern Antarctica. Furthermore, a 1960-80s ice flow speed map in the main glaciers of East Antarctica is produced for the first time.

Origins of native vascular plants of Antarctica: comments from a historical phytogeography viewpoint.

Science.gov (United States)

Mosyakin, S L; Bezusko, L G; Mosyakin, A S

2007-01-01

The article provides an overview of the problem of origin of the only native vascular plants of Antarctica, Deschampsia antartica (Poaceae) and Colobanthus quitensis (Caryophyllaceae), from the viewpoint of modern historical phytogeography and related fields of science. Some authors suggested the Tertiary relict status of these plants in Antarctica, while others favour their recent Holocene immigration. Direct data (fossil or molecular genetic ones) for solving this controversy is still lacking. However, there is no convincing evidence supporting the Tertiary relict status of these plants in Antarctica. Most probably D. antarctica and C. quitensis migrated to Antarctica in the Holocene or Late Pleistocene (last interglacial?) through bird-aided long-distance dispersal. It should be critically tested by (1) appropriate methods of molecular phylogeography, (2) molecular clock methods, if feasible, (3) direct paleobotanical studies, (4) paleoclimatic reconstructions, and (5) comparison with cases of taxa with similar distribution/dispersal patterns. The problem of the origin of Antarctic vascular plants is a perfect model for integration of modern methods of molecular phylogeography and phylogenetics, population biology, paleobiology and paleogeography for solving a long-standing enigma of historical plant geography and evolution.

Planetary geomorphology field studies: Iceland and Antarctica

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Malin, M. C.

1984-01-01

Field studies of terrestrial landforms and the processes that shape them provide new directions to the study of planetary features. These studies, conducted in Iceland and in Antarctica, investigated physical and chemical weathering mechanisms and rates, eolitan processes, mudflow phenomena, drainage development, and catastrophic fluvial and volcanic phenomena. Continuing investigations in Iceland fall in three main catagories: (1) catastrophic floods of the Jokulsa a Fjollum, (2) lahars associated with explosive volcanic eruptions of Askja caldera, and (3) rates of eolian abrasion in cold, volcanic deserts. The ice-free valleys of Antarctica, in particular those in South Victoria Land, have much is common with the surface of Mars. In addition to providing independent support for the application of the Iceland findings to consideration of the martian erosional system, the Antarctic observations also provide analogies to other martian phenomena. For example, a family of sand dunes in Victoria Valley are stabilized by the incorporation of snow as beds.

Reaction of chlorine nitrate with hydrogen chloride and water at Antarctic stratospheric temperatures

Science.gov (United States)

Tolbert, Margaret A.; Rossi, Michel J.; Malhotra, Ripudaman; Golden, David M.

1987-01-01

Laboratory studies of heterogeneous reactions important for ozone depletion over Antarctica are reported. The reaction of chlorine nitrate (ClONO2) with H2O and HCl on surfacers that simulate polar stratospheric clouds are studied at temperatures relevant to the Antarctic stratosphere. The gaseous products of the resulting reactions, HOCl, Cl2O, and Cl2, could readily photolyze in the Antarctic spring to produce active chlorine for ozone depletion. Furthermore, the additional formation of condensed-phase HNO3 could serve as a sink for odd nitrogen species that would otherwise scavenge the active chlorine.

The application of the wilderness concept in Antarctica and Svalbard : A comparison of the respective regulatory systems

NARCIS (Netherlands)

Neumann, Antje

2016-01-01

The wilderness values of Antarctica receive explicit legal protection under the Environmental Protocol to the Antarctic Treaty. However, different opinions exist, on the one hand, as regards the precise meaning of the wilderness concept at the international and national level and, on the other hand,

Report on field research of the Spanish Antarctic Campaign 2014/15: a cooperative international research project with the 56th Japanese Antarctic Research Expedition

Directory of Open Access Journals (Sweden)

Sakae Kudoh

2015-07-01

Full Text Available A study on the limnological and ecological characteristics of maritime Antarctic lakes on Byers Peninsula, Livingstone Island, South Shetland Islands, West Antarctica, was conducted by the Spanish Antarctic Research Campaign during the 2014/15 season, in cooperation with the research program of the 56th Japanese Antarctic Research Expedition. Limnological surveys of three hillside lakes and three lagoons near beaches were conducted under conditions of heavy snow cover. Soils and biological samples in the catchment areas of the lakes and lagoons were also collected and analyzed. The hillside lakes were covered by thick ice and snow, which maintained winter water conditions in the lakes, such as irreversible stratification, oxygen depletion of bottom water, very weak underwater light conditions, etc., even in mid-January, although swimming zooplankton were abundant. Water samples were also collected in coastal lagoons and streams, an environment in which birds and marine mammals transport materials through the aquatic system.

Past Penguin Colony Linkages to Climate Change and Catastrophic Volcanism on the Northern Antarctic Peninsula

Science.gov (United States)

Roberts, S. J.; Monien, P.; Foster, L. C.; Loftfield, J.; Schnetger, B.; Pearson, E. J.; Hocking, E. P.; Fretwell, P.; Ireland, L.; Ochyra, R.; Haworth, A.; Allen, C. S.; Brumsack, H. J.; Bentley, M.; Hodgson, D.

2016-12-01

Recent warming and reductions in sea-ice in some parts of Antarctica are thought to be having a negative impact on populations of `ice-dependent' penguin species (e.g., Emperor, Adélie) that feed at the sea-ice edge because populations of `ice-avoiding'/more `adaptable' species (e.g., Gentoo, Chinstrap) have remained stable or increased, and some Adélie colonies located in areas of sea-ice expansion have increased. This hypothesis is based on short observational records and limited subfossil evidence, but has not been tested over longer, mid-late Holocene, timescales on the Antarctic Peninsula. Between 1950-1997, the northern Antarctic Peninsula was one of the most rapidly warming regions in the Southern Hemisphere and, over the last 30 years, the largest breeding population of Gentoo penguins in Antarctica on Ardley Island, north-western Antarctic Peninsula, has increased. We tracked past changes in the Ardley Island penguin colony size by comparing detailed biogeochemical analysis of an 8,500-year Ardley Lake sediment profile with past records of penguin presence, climate and sea-ice extent across the Antarctic Peninsula and found that the colony also responded positively during some local-regionally warmer parts of the late Holocene. However, at least three large volcanic eruptions from nearby Deception Island had a devastating impact on the colony between 7000-2000 years ago, with colony recovery taking up to 800 years following the most disruptive period of volcanic activity c. 5500-5000 years ago.

Modeling Antarctic Ice Sheet retreat in warm climates: a historical perspective.

Science.gov (United States)

Pollard, D.; Deconto, R. M.; Gasson, E.

2016-12-01

Early modeling of Antarctic Ice Sheet size vs. climate focused on asymmetry between retreat and growth, with much greater warming needed to cause retreat from full ice cover, due to Height Mass Balance Feedback and albedo feedback. This led to a long-standing model-data conflict, with models needing 1000 to2000 ppmv atmospheric CO2 to produce retreat from full size, vs. proxy data of large ice fluctuations despite much lower CO2 since the Miocene.Subsequent modeling with marine ice physics found that the West Antarctic Ice Sheet could undergo repeated warm-period collapses with realistic past forcing. However, that yields only 3 to 7 m equivalent sea-level rise above modern, compared to 10 to 20 m or more suggested by some geologic data. Large subglacial basins in East Antarctica could be vulnerable to the same processes,but did not retreat in most models due to narrower and shallower sills.After recent modifications, some ice sheet models were able to produce warm-period collapse of major East Antarctic basins, with sea-level rise of up to 15 m. The modifications are (i) hydrofracturing by surface melt, and structural failure of ice cliffs, or (ii) numerical treatment at the grounding line. In these models, large retreat occurs both for past warmintervals, and also for future business-as-usual scenarios.Some interpretations of data in the late Oligocene and Miocene suggest yet larger fluctuations, between 50 to 100% of modern Antarctic size. That would require surface-melt driven retreat of some terrestrial East Antarctic ice, despite the hysteresis issue raised above. A recent study using a coupled climate-ice sheet model found that with a finer climate gridand more frequent coupling exchange, substantial retreat of terrestrial Antarctica can occur with 500 to 840 ppmv CO2, much lower than in earlier models. This will allow meaningful interactions between modeling and deeper-time geologic interpretations since the late Oligocene.

Pseudonotohymena antarctica n. g., n. sp. (Ciliophora, Hypotricha), a New Species from Antarctic Soil.

Science.gov (United States)

Park, Kyung-Min; Jung, Jae-Ho; Min, Gi-Sik; Kim, Sanghee

2017-07-01

A new soil ciliate, Pseudonotohymena antarctica n. g., n. sp., from King George Island, Antarctica, is described based on live observation, protargol impregnation, and its 18S rRNA gene. The new genus Pseudonotohymena is morphologically similar to the genus Notohymena Blatterer and Foissner in the following characteristics: 18 fronto-ventral-transverse cirri, a flexible body, undulating membranes, dorsomarginal kineties, and the number of cirri in the marginal rows. However, Pseudonotohymena differs from Notohymena particularly in the dorsal ciliature, that is, in possessing a nonfragmented dorsal kinety (vs. fragmented). In addition, the molecular phylogenetic relationship of the new species differs from that of Notohymena species. On the basis of the morphological features, the genetic data, and morphogenesis, we establish P. antarctica n. g., n. sp. In addition, the cyst morphology of this species is described. © 2016 The Author(s) Journal of Eukaryotic Microbiology © 2016 International Society of Protistologists.

Protection of Antarctic microbial communities – ‘out of sight, out of mind’

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Hughes, Kevin A.; Cowan, Don A.; Wilmotte, Annick

2015-01-01

Recent advances in molecular biology techniques have shown the presence of diverse microbial communities and endemic species in Antarctica. Endemic microbes may be a potential source of novel biotechnologically important compounds, including, for example, new antibiotics. Thus, the scientific and biotechnological value of Antarctic terrestrial microbial habitats can be compromised by human visitation to a greater extent than previously realized. The ever-increasing human footprint in Antarctica makes consideration of this topic more pressing, as the number of locations known to be pristine habitats, where increasingly sophisticated cutting-edge research techniques may be used to their full potential, declines. Examination of the Protected Areas system of the Antarctic Treaty shows that microbial habitats are generally poorly protected. No other continent on Earth is dominated to the same degree by microbial species, and real opportunities exist to develop new ways of conceptualizing and implementing conservation of microbial biogeography on a continental scale. Here we highlight potential threats both to the conservation of terrestrial microbial ecosystems, and to future scientific research requiring their study. PMID:25762992

Combined ground-based and satellite remote sensing of atmospheric aerosol and Earth surface in the Antarctic

Science.gov (United States)

Chaikovsky, Anatoli; Korol, Michail; Malinka, A.; Zege, E.; Katsev, I.; Prikhach, A.; Denisov, S.; Dick, V.; Goloub, P.; Blarel, L.; Chaikovskaya, L.; Lapyonok, A.; Podvin, T.; Denishchik-Nelubina, N.; Fedarenka, A.; Svidinsky, V.

2016-01-01

The paper presents lecture materials given at the Nineteenth International Conference and School on Quantum Electronics "Laser Physics and Applications" (19th ICSQE) in 2016, Sozopol, Bulgaria and contains the results of the 10-year research of Belarusian Antarctic expeditions to study the atmospheric aerosol and Earth surface in Antarctica. The works focus on the studying variability and trends of aerosol, cloud and snow characteristics in the Antarctic and the links of these processes with the long range transport of atmospheric pollutants and climate changes.

Surface reflectance of Antarctic bryophytes and protection from UV and visible light

International Nuclear Information System (INIS)

Robinson, S.A.; Wasley, J.; Turnbull, J.

2000-01-01

Full text: As well as determining the amount of solar radiation available for photosynthesis, the surface reflectance and absorptance characteristics of plants are their first defence against damaging effects of solar radiation. The solar spectrum can be damaging to plants in many ways. At shorter wavelengths, UV-B (280-320 nm) radiation can cause lesions in nucleic acid and proteins. Excess levels of visible radiation (400-750) can cause photoinhibition whilst high absorbtance of longer wavelengths (>750) leads to increases in temperature that can be detrimental in some environments. The adaptation of surface reflectance properties of vascular plants to particular environments are well known in some ecosystems. For example in desert ecosystems pubescent leaf surfaces that increase reflectance are common and have been demonstrated to be important to protection from photoinhibition. The epidermal characteristics of some plants are also known to change in absorptance, due to the accumulation of specific compounds. For example flavonoids which are effective screens against UV-B radiation, increase upon exposure to UV-B radiation. In this study we surveyed the natural variability in surface reflectance in mosses growing in continental Antarctica. Antarctica is experiencing large increases in incident UV-B radiation due to reductions in concentrations of stratospheric ozone. Additionally over the summer months (November January), when moss is exposed to direct sunlight, levels of visible solar radiation are also high, increasing the likelihood of photoinhibitory damage in moss. Our aim in this study is to describe the natural variability in the surface reflectance characteristics of moss, such that we have a baseline with which to assess future changes in response to changes in global climate, and imposed experimental treatments, and also to develop hypotheses with respect to how mosses have adapted to the cold and arid antarctic environment. Variability in surface

Crustal thickness of Antarctica estimated using data from gravimetric satellites

Science.gov (United States)

Llubes, Muriel; Seoane, Lucia; Bruinsma, Sean; Rémy, Frédérique

2018-04-01

Computing a better crustal thickness model is still a necessary improvement in Antarctica. In this remote continent where almost all the bedrock is covered by the ice sheet, seismic investigations do not reach a sufficient spatial resolution for geological and geophysical purposes. Here, we present a global map of Antarctic crustal thickness computed from space gravity observations. The DIR5 gravity field model, built from GOCE and GRACE gravimetric data, is inverted with the Parker-Oldenburg iterative algorithm. The BEDMAP products are used to estimate the gravity effect of the ice and the rocky surface. Our result is compared to crustal thickness calculated from seismological studies and the CRUST1.0 and AN1 models. Although the CRUST1.0 model shows a very good agreement with ours, its spatial resolution is larger than the one we obtain with gravimetric data. Finally, we compute a model in which the crust-mantle density contrast is adjusted to fit the Moho depth from the CRUST1.0 model. In East Antarctica, the resulting density contrast clearly shows higher values than in West Antarctica.

Antarctic climate and ice-sheet configuration during the early Pliocene interglacial at 4.23 Ma

Science.gov (United States)

Golledge, Nicholas R.; Thomas, Zoë A.; Levy, Richard H.; Gasson, Edward G. W.; Naish, Timothy R.; McKay, Robert M.; Kowalewski, Douglas E.; Fogwill, Christopher J.

2017-07-01

The geometry of Antarctic ice sheets during warm periods of the geological past is difficult to determine from geological evidence, but is important to know because such reconstructions enable a more complete understanding of how the ice-sheet system responds to changes in climate. Here we investigate how Antarctica evolved under orbital and greenhouse gas conditions representative of an interglacial in the early Pliocene at 4.23 Ma, when Southern Hemisphere insolation reached a maximum. Using offline-coupled climate and ice-sheet models, together with a new synthesis of high-latitude palaeoenvironmental proxy data to define a likely climate envelope, we simulate a range of ice-sheet geometries and calculate their likely contribution to sea level. In addition, we use these simulations to investigate the processes by which the West and East Antarctic ice sheets respond to environmental forcings and the timescales over which these behaviours manifest. We conclude that the Antarctic ice sheet contributed 8.6 ± 2.8 m to global sea level at this time, under an atmospheric CO2 concentration identical to present (400 ppm). Warmer-than-present ocean temperatures led to the collapse of West Antarctica over centuries, whereas higher air temperatures initiated surface melting in parts of East Antarctica that over one to two millennia led to lowering of the ice-sheet surface, flotation of grounded margins in some areas, and retreat of the ice sheet into the Wilkes Subglacial Basin. The results show that regional variations in climate, ice-sheet geometry, and topography produce long-term sea-level contributions that are non-linear with respect to the applied forcings, and which under certain conditions exhibit threshold behaviour associated with behavioural tipping points.

Lithospheric Structure of Antarctica and Implications for Geological and Cryospheric Evolution

Science.gov (United States)

Wiens, Douglas; Heeszel, David; Sun, Xinlei; Lloyd, Andrew; Nyblade, Andrew; Anandakrishnan, Sridhar; Aster, Richard; Chaput, Julien; Huerta, Audrey; Hansen, Samantha; Wilson, Terry

2013-04-01

Recent broadband seismic deployments, including the AGAP/GAMSEIS array of 24 broadband seismographs over the Gamburtsev Subglacial Mountains (GSM) in East Antarctica and the POLENET/ANET deployment of 33 seismographs across much of West Antarctica, reveal the detailed crust and upper mantle structure of Antarctica for the first time. The seismographs operate year-around even in the coldest parts of Antarctica, due to novel insulated boxes, power systems, and modified instrumentation developed in collaboration with the IRIS PASSCAL Instrument Center. We analyze the data using several different techniques to develop high-resolution models of Antarctic seismic structure. We use Rayleigh wave phase velocities at periods of 20-180 s determined using a modified two-plane wave decomposition of teleseismic Rayleigh waves to invert for the three dimensional shear velocity structure. In addition, Rayleigh wave group and phase velocities obtained by ambient seismic noise correlation methods provide constraints at shorter periods and shallower depths. Receiver functions provide precise estimates of crustal structure beneath the stations, and P and S wave tomography provides models of upper mantle structure down to ~ 500 km depth along transects of greater seismic station density. The new seismic results show that the high elevations of the GSM are supported by thick crust (~ 55 km), and are underlain by thick Precambrian continental lithosphere that initially formed during Archean to mid-Proterozoic times. The absence of lithospheric thermal anomalies suggests that the mountains were formed by a compressional orogeny during the Paleozoic, thus providing a locus for ice sheet nucleation throughout a long period of geological time. Within West Antarctica, the crust and lithosphere are extremely thin near the Transantarctic Mountain Front and topographic lows such as the Bentley Trench and Byrd Basin, which represent currently inactive Cenozoic rift systems. Slow seismic

Accelerated ice-sheet mass loss in Antarctica from 18-year satellite laser ranging measurements

Directory of Open Access Journals (Sweden)

Shuanggen Jin

2016-02-01

Full Text Available Accurate estimate of the ice-sheet mass balance in Antarctic is very difficult due to complex ice sheet condition and sparse in situ measurements. In this paper, the low-degree gravity field coefficients of up to degree and order 5 derived from Satellite Laser Ranging (SLR measurements are used to determine the ice mass variations in Antarctica for the period 1993–2011. Results show that the ice mass is losing with -36±13 Gt/y in Antarctica, -42±11 Gt/y in the West Antarctica and 6±10 Gt/y in the East Antarctica from 1993 to 2011. The ice mass variations from the SLR 5×5 have a good agreement with the GRACE 5×5, GRACE 5×5 (1&2 and GRACE (60×60 for the entire continent since 2003, but degree 5 from SLR is not sufficient to quantify ice losses in West and East Antarctica, respectively. The rate of ice loss in Antarctica is -28±17 Gt/y for 1993-2002 and -55±17 Gt/y for 2003-2011, indicating significant accelerated ice mass losses since 2003. Furthermore, the results from SLR are comparable with GRACE measurements.

Constraining the Antarctic contribution to interglacial sea-level rise

Science.gov (United States)

Naish, T.; Mckay, R. M.; Barrett, P. J.; Levy, R. H.; Golledge, N. R.; Deconto, R. M.; Horgan, H. J.; Dunbar, G. B.

2015-12-01

Observations, models and paleoclimate reconstructions suggest that Antarctica's marine-based ice sheets behave in an unstable manner with episodes of rapid retreat in response to warming climate. Understanding the processes involved in this "marine ice sheet instability" is key for improving estimates of Antarctic ice sheet contribution to future sea-level rise. Another motivating factor is that far-field sea-level reconstructions and ice sheet models imply global mean sea level (GMSL) was up to 20m and 10m higher, respectively, compared with present day, during the interglacials of the warm Pliocene (~4-3Ma) and Late Pleistocene (at ~400ka and 125ka). This was when atmospheric CO2 was between 280 and 400ppm and global average surface temperatures were 1- 3°C warmer, suggesting polar ice sheets are highly sensitive to relatively modest increases in climate forcing. Such magnitudes of GMSL rise not only require near complete melt of the Greenland Ice Sheet and the West Antarctic Ice Sheet, but a substantial retreat of marine-based sectors of East Antarctic Ice Sheet. Recent geological drilling initiatives on the continental margin of Antarctica from both ship- (e.g. IODP; International Ocean Discovery Program) and ice-based (e.g. ANDRILL/Antarctic Geological Drilling) platforms have provided evidence supporting retreat of marine-based ice. However, without direct access through the ice sheet to archives preserved within sub-glacial sedimentary basins, the volume and extent of ice sheet retreat during past interglacials cannot be directly constrained. Sediment cores have been successfully recovered from beneath ice shelves by the ANDRILL Program and ice streams by the WISSARD (Whillans Ice Stream Sub-glacial Access Research Drilling) Project. Together with the potential of the new RAID (Rapid Access Ice Drill) initiative, these demonstrate the technological feasibility of accessing the subglacial bed and deeper sedimentary archives. In this talk I will outline the

‘Antarctica – A Wilderness Continent for Science : The ‘Public’s Dream’ as a Mission Impossible?’

NARCIS (Netherlands)

Bastmeijer, Kees; Tin, Tina

2014-01-01

The Consultative Parties to the Antarctic Treaty have frequently declared their collective ambition to manage Antarctica “in the interest of all mankind”. However, the concrete implications of these declarations are not clear. As part of an international research project, the authors asked people

A 25-year Record of Antarctic Ice Sheet Elevation and Mass Change

Science.gov (United States)

Shepherd, A.; Muir, A. S.; Sundal, A.; McMillan, M.; Briggs, K.; Hogg, A.; Engdahl, M.; Gilbert, L.

2017-12-01

Since 1992, the European Remote-Sensing (ERS-1 and ERS-2), ENVISAT, and CryoSat-2 satellite radar altimeters have measured the Antarctic ice sheet surface elevation, repeatedly, at approximately monthly intervals. These data constitute the longest continuous record of ice sheet wide change. In this paper, we use these observations to determine changes in the elevation, volume and mass of the East Antarctic and West Antarctic ice sheets, and of parts of the Antarctic Peninsula ice sheet, over a 25-year period. The root mean square difference between elevation rates computed from our survey and 257,296 estimates determined from airborne laser measurements is 54 cm/yr. The longevity of the satellite altimeter data record allows to identify and chart the evolution of changes associated with meteorology and ice flow, and we estimate that 3.6 % of the continental ice sheet, and 21.7 % of West Antarctica, is in a state of dynamical imbalance. Based on this partitioning, we estimate the mass balance of the East and West Antarctic ice sheet drainage basins and the root mean square difference between these and independent estimates derived from satellite gravimetry is less than 5 Gt yr-1.

Characterization of bacterial consortia for its use in bioremediation of gas-oil contaminated antarctic soils

International Nuclear Information System (INIS)

Ruberto, L.; Vazquez, S.; Mestre, C.; Nogales, B.; Christie-Oleza, J.; Bosch, R.; Mac Cormack, W. P.

2009-01-01

Success of bio augmentation of chronically-contaminated soils is controversial, mainly because the inocula are frequently unable to establish in the matrix under bioremediation. In Antarctica, the environmental conditions and the restriction for the introduction of non-autochthonous organisms (imposed by the Antarctic Treaty) prevent inoculation with foreign bacteria. (Author)

Antarctic glaciation caused ocean circulation changes at the Eocene-Oligocene transition.

Science.gov (United States)

Goldner, A; Herold, N; Huber, M

2014-07-31

Two main hypotheses compete to explain global cooling and the abrupt growth of the Antarctic ice sheet across the Eocene-Oligocene transition about 34 million years ago: thermal isolation of Antarctica due to southern ocean gateway opening, and declining atmospheric CO2 (refs 5, 6). Increases in ocean thermal stratification and circulation in proxies across the Eocene-Oligocene transition have been interpreted as a unique signature of gateway opening, but at present both mechanisms remain possible. Here, using a coupled ocean-atmosphere model, we show that the rise of Antarctic glaciation, rather than altered palaeogeography, is best able to explain the observed oceanographic changes. We find that growth of the Antarctic ice sheet caused enhanced northward transport of Antarctic intermediate water and invigorated the formation of Antarctic bottom water, fundamentally reorganizing ocean circulation. Conversely, gateway openings had much less impact on ocean thermal stratification and circulation. Our results support available evidence that CO2 drawdown--not gateway opening--caused Antarctic ice sheet growth, and further show that these feedbacks in turn altered ocean circulation. The precise timing and rate of glaciation, and thus its impacts on ocean circulation, reflect the balance between potentially positive feedbacks (increases in sea ice extent and enhanced primary productivity) and negative feedbacks (stronger southward heat transport and localized high-latitude warming). The Antarctic ice sheet had a complex, dynamic role in ocean circulation and heat fluxes during its initiation, and these processes are likely to operate in the future.

Chilean Antarctic Stations on King George Island

Directory of Open Access Journals (Sweden)

Katsutada Kaminuma

2000-07-01

Full Text Available The purpose of my visit to Chilean Antarctic Stations was to assess the present status of geophysical observations and research, as the South Shetland Island, West Antarctica, where the stations are located, are one of the most active tectonic regions on the Antarctic plate. The Instituto Antartico Chileno (INACH kindly gave me a chance to stay in Frei/Escudero Bases as an exchange scientist under the Antarctic Treaty for two weeks in January 2000. I stayed in Frei Base as a member of a geological survey group named "Tectonic Evolution of the Antarctic Peninsula" which was organized by Prof. F. Herve, University of Chile, from January 05 to 19,2000. All my activity in the Antarctic was organized by INACH. During my stay in Frei Base, I also visited Bellingshausen (Russian, Great Wall (China and Artigas (Uruguay stations. All these stations are located within walking distance of Frei Base. King Sejong Station (Korea, located 10km east from Frei Base, and Jubany Base (Argentine, another 6km south-east from King Sejong Station, were also visited with the aid of a zodiac boat that was kindly operated for us by King Sejong Station. All stations except Escudero Base carry out meteorological observations. The seismological observations in Frei Base are operated by Washington State University of the U. S. monitoring of earthquake activity and three-component geomagnetic observations are done at King Sejong and Great Wall stations. Earth tide is monitored at Artigas Base. Continuous monitoring of GPS and gravity change are planned at King Sejong Station in the near future. Scientific research activities of each country in the area in the 1999/2000 Antarctic summer season were studied and the logistic ability of all stations was also assessed for our future international cooperation.

Estimating Past Temperature Change in Antarctica Based on Ice Core Stable Water Isotope Diffusion

Science.gov (United States)

Kahle, E. C.; Markle, B. R.; Holme, C.; Jones, T. R.; Steig, E. J.

2017-12-01

The magnitude of the last glacial-interglacial transition is a key target for constraining climate sensitivity on long timescales. Ice core proxy records and general circulation models (GCMs) both provide insight on the magnitude of climate change through the last glacial-interglacial transition, but appear to provide different answers. In particular, the magnitude of the glacial-interglacial temperature change reconstructed from East Antarctic ice-core water-isotope records is greater ( 9 degrees C) than that from most GCM simulations ( 6 degrees C). A possible source of this difference is error in the linear-scaling of water isotopes to temperature. We employ a novel, nonlinear temperature-reconstruction technique using the physics of water-isotope diffusion to infer past temperature. Based on new, ice-core data from the South Pole, this diffusion technique suggests East Antarctic temperature change was smaller than previously thought. We are able to confirm this result using a simple, water-isotope fractionation model to nonlinearly reconstruct temperature change at ice core locations across Antarctica based on combined oxygen and hydrogen isotope ratios. Both methods produce a temperature change of 6 degrees C for South Pole, agreeing with GCM results for East Antarctica. Furthermore, both produce much larger changes in West Antarctica, also in agreement with GCM results and independent borehole thermometry. These results support the fidelity of GCMs in simulating last glacial maximum climate, and contradict the idea, based on previous work, that the climate sensitivity of current GCMs is too low.

Mercury accumulation in sediments and seabird feathers from the Antarctic Peninsula

International Nuclear Information System (INIS)

Calle, Paola; Alvarado, Omar; Monserrate, Lorena; Cevallos, Juan Manuel; Calle, Nastenka; Alava, Juan José

2015-01-01

Highlights: • We assessed mercury bioaccumulation in seabirds in the Antarctic Peninsula. • Levels of Hg were higher in gentoo penguins & brown skuas than chinstrap penguins. • Mercury BMF in the brown skua/penguins relationship was higher than 1. • Long-range environmental transport is the likely mercury route in Antarctic. - Abstract: In an effort to assess the impact of mercury in the Antarctic Peninsula, we conducted ecotoxicological research in this region during the summer of 2012 and 2013. The objectives were to assess: (a) mercury levels in sediment samples; (b) mercury accumulation in Antarctic seabird feathers: Catharacta lonnbergi (brown skua), Pygoscelis papua (gentoo penguin) and Pygoscelis antarctica (chinstrap penguin); and (c) biomagnification (BMF predator/prey) and biota sediment accumulation (BSAF skuas/sediment) factors. Mercury concentrations in sediment were relatively low. Mercury concentrations were significantly higher in brown skuas and gentoo penguins than in chinstrap penguins (2012), and significantly higher in brown skuas than in both penguins (2013). BMF indicated 2–7.5 times greater mercury levels in brown skuas than in penguins. BSAF values suggested an apparent temporal decrease of 18.2% of this ratio from 2012 to 2013. Long-range environmental transport is the likely route of entry of mercury into the Antarctic Peninsula

Cytogenetic, cellular, and developmental responses in antarctic sea urchins (Sterechinus neumayeri) following laboratory ultraviolet-B and ambient solar radiation exposures

International Nuclear Information System (INIS)

Anderson, S.; Hoffman, J.; Wild, G.; Bosch, I.; Karentz, D.

1993-01-01

Increasing ultraviolet-B radiation as a consequence of springtime ozone depletion, could harm antarctic ecosystems. This study uses several techniques for studying genotoxic effects to evaluate UV-B effects in sea urchins from Antarctica. 6 refs., 2 figs

Exploring the effect of East Antarctic ice mass loss on GIA-induced horizontal bedrock motions

Science.gov (United States)

Konfal, S. A.; Whitehouse, P. L.; Hermans, T.; van der Wal, W.; Wilson, T. J.; Bevis, M. G.; Kendrick, E. C.; Dalziel, I.; Smalley, R., Jr.

2017-12-01

Ice history inputs used in Antarctic models of GIA include major centers of ice mass loss in West Antarctica. In the Transantarctic Mountains (TAM) region spanning the boundary between East and West Antarctica, horizontal crustal motions derived from GPS observations from the Antarctic Network (ANET) component of the Polar Earth Observing Network (POLENET) are towards these West Antarctic ice mass centers, opposite to the pattern of radial crustal motion expected in an unloading scenario. We investigate alternative ice history and earth structure inputs to GIA models in an attempt to reproduce observed crustal motions in the region. The W12 ice history model is altered to create scenarios including ice unloading in the Wilkes Subglacial Basin based on available glaciological records. These altered ice history models, along with the unmodified W12 ice history model, are coupled with 60 radially varying (1D) earth model combinations, including approximations of optimal earth profiles identified in published GIA models. The resulting model-predicted motions utilizing both the modified and unmodified ice history models fit ANET GPS-derived crustal motions in the northern TAM region for a suite of earth model combinations. Further south, where the influence of simulated Wilkes unloading is weakest and West Antarctic unloading is strongest, observed and predicted motions do not agree. The influence of simulated Wilkes ice unloading coupled with laterally heterogeneous earth models is also investigated. The resulting model-predicted motions do not differ significantly between the original W12 and W12 with simulated Wilkes unloading ice histories.

Chlorinated biphenyls and pesticides in migrating and resident seabirds from East and West Antarctica.

Science.gov (United States)

Corsolini, Simonetta; Borghesi, Nicoletta; Ademollo, Nicoletta; Focardi, Silvano

2011-11-01

The unhatched eggs of the following seabirds were analyzed to quantify PCBs, hexachlorobenzene (HCB), α-, β-, γ-, δ-hexachlorocyclohexanes (HCHs), o,p' and p,p' isomers of DDT, DDD and DDE: resident Adèlie (Pygoscelis adèliae, ADPE) and Emperor (Aptenodytes forsteri, EMPE) penguins, migrating snow petrel (Pagodroma nivea, SNPT) and South Polar skua (Catharacta maccormicki, SPSK) from the Ross Sea (East Antarctica); and migrating Brown skua (Catharacta antartica, BRSK) and resident ADPE from the Brainsfield Strait (West Antarctica). The general aims were to evaluate the contaminant accumulation in eggs of migrating and resident species in the two study areas, and to compare levels in penguins and skuas nesting in East and West Antarctica. PCB congener and HCH and DDT isomer profiles were also assessed. Comparisons were evaluated using seven PCB congeners (IUPAC nos. 28, 52, 101, 118+149, 138, 153, and 180), p,p'-DDE, ΣDDTs, and ΣHCHs. Higher contaminant concentrations were detected in migrating seabirds (South polar skua and brown skua)>sub-Antarctic species (snow petrel)>Antarctic species (penguins) from both the sampling sites, suggesting contamination events at lower latitudes for those birds migrating northward. HCHs showed the lowest concentrations in all species (from 0.03±0.03 ng/g wet wt in SPSK to 1.81±1.23 ng/g wet wt in ADPE from West Antarctica), and PCBs were the most abundant contaminants (from 4.34±2.15 ng/g wet wt. in EMPE to 53.41±19.61 ng/g wet wt. in brown skua). Among pesticides, it is relevant the detection of p,p'-DDT in Adèlie penguin from West Antarctica and in both species of skua; the detection of this pesticide can confirm its actual use in certain malaria-endemic countries from where it is transferred through the long range transport to the polar regions. Contaminants did not show any significant temporal trend during a ten year time span, from 1994/95 to 2004/05, in organisms collected in East Antarctica and they did not

The Signature of Southern Hemisphere Atmospheric Circulation Patterns in Antarctic Precipitation.

Science.gov (United States)

Marshall, Gareth J; Thompson, David W J; van den Broeke, Michiel R

2017-11-28

We provide the first comprehensive analysis of the relationships between large-scale patterns of Southern Hemisphere climate variability and the detailed structure of Antarctic precipitation. We examine linkages between the high spatial resolution precipitation from a regional atmospheric model and four patterns of large-scale Southern Hemisphere climate variability: the southern baroclinic annular mode, the southern annular mode, and the two Pacific-South American teleconnection patterns. Variations in all four patterns influence the spatial configuration of precipitation over Antarctica, consistent with their signatures in high-latitude meridional moisture fluxes. They impact not only the mean but also the incidence of extreme precipitation events. Current coupled-climate models are able to reproduce all four patterns of atmospheric variability but struggle to correctly replicate their regional impacts on Antarctic climate. Thus, linking these patterns directly to Antarctic precipitation variability may allow a better estimate of future changes in precipitation than using model output alone.

Mercury accumulation in sediments and seabird feathers from the Antarctic Peninsula.

Science.gov (United States)

Calle, Paola; Alvarado, Omar; Monserrate, Lorena; Cevallos, Juan Manuel; Calle, Nastenka; Alava, Juan José

2015-02-28

In an effort to assess the impact of mercury in the Antarctic Peninsula, we conducted ecotoxicological research in this region during the summer of 2012 and 2013. The objectives were to assess: (a) mercury levels in sediment samples; (b) mercury accumulation in Antarctic seabird feathers: Catharacta lonnbergi (brown skua), Pygoscelis papua (gentoo penguin) and Pygoscelis antarctica (chinstrap penguin); and (c) biomagnification (BMF predator/prey) and biota sediment accumulation (BSAF skuas/sediment) factors. Mercury concentrations in sediment were relatively low. Mercury concentrations were significantly higher in brown skuas and gentoo penguins than in chinstrap penguins (2012), and significantly higher in brown skuas than in both penguins (2013). BMF indicated 2-7.5 times greater mercury levels in brown skuas than in penguins. BSAF values suggested an apparent temporal decrease of 18.2% of this ratio from 2012 to 2013. Long-range environmental transport is the likely route of entry of mercury into the Antarctic Peninsula. Copyright © 2014 Elsevier Ltd. All rights reserved.

In vitro immunobiological activity of an Antarctic streptomyces polysaccharide

International Nuclear Information System (INIS)

Toshkova, R.; Yossifova, L.; Gardeva, E.; Zvetkova, E.; Ivanova, V.

2010-01-01

Antarctic Streptomyces sp. 1010, were obtained from sea water samples (Livingston Island, Antarctica), during the Third Bulgarian Antarctic Scientific Expedition (1994-1995). The ecophysiological methods for isolation and characterization of these active, cold-adapted, Gram-positive microorganisms (psychrophiles) in morphological, phenotypic, genetic and taxonomic aspects, have been earlier reported. In this study, a new extracellular polysaccharide (heteropolysaccharide) has been isolated and purified from cultured broth of the Antarctic Streptomyces sp. 1010. The monosaccharide content of the Antarctic streptomyces heteropolysaccharide has been examined by TLC and GC/MS. The mitogenic and immuno potential properties of the purified Antarctic Streptomyces polysaccharide (ASMP) have been studied in vitro - in the short-term cultures of human peripheral blood mononuclear cells (hPBMCs - lymphocytes and monocytes) and mouse spleen lymphocytes (mouse splenocytes - mSps). The results obtained show that ASMP has a double lectin-like effect on the proliferative activity of hPBMCs: similar to this of Con A on the lymphoid cells (preliminary T-lymphocytes) and to the effect of LPS on the mononuclear from monocyte-macrophage lineage. Expressed as proliferative index (PI), the mitogenic response of mSps to the in vitro influence of ASMP was also higher than PI in the negative, as well as in the positive controls (mSps, cultured in the presence of PHA, Con A and LPS). The new Antarctic Streptomyces' heteropolysaccharide examined could be useful in the future as an immunomodulative biologically active substance and its extracellular production may contribute to the development of thermobiochemistry, immunomodulative drug therapy and immunopharmaceutical industry. (authors)

NASA-ISRO synthetic aperture radar (NISAR) for temporal tracking of iceberg calving events in the Antarctica

Science.gov (United States)

Jawak, S. D.; Luis, A. J.

2017-12-01

Estimating mass loss of the Antarctic ice sheet caused by iceberg calving is a challenging job. Antarctica is surrounded by a variety of large, medium and small sized ice shelves, glacier tongues and coastal areas without offshore floating ice masses. It is possible to monitor surface structures on the continental ice and the ice shelves as well as calved icebergs using NASA-ISRO synthetic aperture radar (NISAR) satellite images in future. The NISAR, which is planned to be launched in 2020, can be used as an all-weather and all-season system to classify the coastline of Antarctica to map patterns of surface structures close to the calving front. Additionally, classifying patterns and density of surface structures distributed over the ice shelves and ice tongues can be a challenging research where NISAR can be of a great advantage. So this work explores use of NISAR to map surface structures visible on ice shelves which can provide advisories to field teams. The ice shelf fronts has been categorized into various classes based on surface structures relative to the calving front within a 30 km-wide seaward strip. The resulting map of the classified calving fronts around Antarctica and their description would provide a detailed representation of crevasse formation and dominant iceberg in the southern ocean which pose a threat to navigation of Antarctic bound ships.

Tailoring Peptidomimetics Antifreeze Protein from Exotic Antarctic Marine

International Nuclear Information System (INIS)

Mohd Basyaruddin Abdul Rahman; Azren Aida Asmawi; Emilia Abdulmalek

2016-01-01

Antifreeze proteins (AFPs) are synthesized by various cold-adapted organisms to enable them to survive in subzero environment. The unique role of AFPs recently attracted enormous interest to develop them as commercial products. In this work, we have studied the antifreeze activity of short helical protein fragments (peptides) instead of the entire antifreeze protein of Antarctic yeast Glaciozyma antarctica. Several short peptide segments were designed according to amino acid sequence of helical region of AFP-1 G.antarctica, which are assumed to be involved in its antifreeze activity. We have demonstrated that short peptide segments derived from yeast AFP possess antifreeze activity and result in modification of the ice crystals growth rates and habits. This strategy has enabled the preparation of short AFP with high antifreeze activity in large amount of quantities at a low cost further opens the chance of developing the commercial potentials of AFPs.(author)

Vertical structure of Antarctic tropospheric ozone depletion events: characteristics and broader implications

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A. E. Jones

2010-08-01

Full Text Available The majority of tropospheric ozone depletion event (ODE studies have focussed on time-series measurements, with comparatively few studies of the vertical component. Those that exist have almost exclusively used free-flying balloon-borne ozonesondes and almost all have been conducted in the Arctic. Here we use measurements from two separate Antarctic field experiments to examine the vertical profile of ozone during Antarctic ODEs. We use tethersonde data to probe details in the lowest few hundred meters and find considerable structure in the profiles associated with complex atmospheric layering. The profiles were all measured at wind speeds less than 7 ms⁻¹, and on each occasion the lowest inversion height lay between 10 m and 40 m. We also use data from a free-flying ozonesonde study to select events where ozone depletion was recorded at altitudes >1 km above ground level. Using ERA-40 meteorological charts, we find that on every occasion the high altitude depletion was preceded by an atmospheric low pressure system. An examination of limited published ozonesonde data from other Antarctic stations shows this to be a consistent feature. Given the link between BrO and ODEs, we also examine ground-based and satellite BrO measurements and find a strong association between atmospheric low pressure systems and enhanced BrO that must arise in the troposphere. The results suggest that, in Antarctica, such depressions are responsible for driving high altitude ODEs and for generating the large-scale BrO clouds observed from satellites. In the Arctic, the prevailing meteorology differs from that in Antarctica, but, while a less common effect, major low pressure systems in the Arctic can also generate BrO clouds. Such depressions thus appear to be fundamental when considering the broader influence of ODEs, certainly in Antarctica, such as halogen export and the radiative influence of ozone-depleted air masses.

Skin hydration, microrelief and greasiness of normal skin in Antarctica.

Science.gov (United States)

Tsankov, N; Mateev, D; Darlenski, R

2018-03-01

The skin is the primary defence of the human body against external factors from physical, chemical, mechanical and biologic origin. Climatic factors together with low temperature and sun radiation affect the skin. The effect of climatic conditions in Antarctica on healthy skin has not been previously addressed. The aim of this study was to evaluate the changes in the skin hydration, greasiness and microrelief due to the extreme climatic environmental factors during the stay of the members of the Bulgarian Antarctic expedition. Fifty-nine Caucasian healthy subjects, 42 men and 17 women with mean age 50.9 years (27-68), were enrolled. The study was performed in five consecutive years from 2011 to 2016 at the Bulgarian Antarctic base camp at Livingston Island. The study protocol consisted of two parts: study A: duration of 15 days with measurement of skin physiology parameters on a daily basis, and study B: five measurements at baseline and at days 14, 30, 45 and 50 upon arrival in Antarctica. We measured three biophysical parameters related to skin physiology at cheek skin by an impedance measuring device. No statistically significant difference between parameters at the different measurement points. There is a variation in skin hydration reaching its lower point at day 11 and then returning to values similar to baseline. Initially, an increase in skin greasiness was witnessed with a sharp depression at day 11 and final values at day 15 resembling the ones at baseline. An increase, although not statistically significant, in skin roughness was observed in the first 15 days of the study. Study B showed no statistically significant variances between values of the three parameters. Our studies show the pioneer results of the effect of Antarctic climate on human skin physiology. © 2017 European Academy of Dermatology and Venereology.

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

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S. Albani

2012-04-01

Full Text Available 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.

Precipitation regime influence on oxygen triple-isotope distributions in Antarctic precipitation and ice cores

Science.gov (United States)

Miller, Martin F.

2018-01-01

The relative abundance of 17O in meteoric precipitation is usually reported in terms of the 17O-excess parameter. Variations of 17O-excess in Antarctic precipitation and ice cores have hitherto been attributed to normalised relative humidity changes at the moisture source region, or to the influence of a temperature-dependent supersaturation-controlled kinetic isotope effect during in-cloud ice formation below -20 °C. Neither mechanism, however, satisfactorily explains the large range of 17O-excess values reported from measurements. A different approach, based on the regression characteristics of 103 ln (1 +δ17 O) versus 103 ln (1 +δ18 O), is applied here to previously published isotopic data sets. The analysis indicates that clear-sky precipitation ('diamond dust'), which occurs widely in inland Antarctica, is characterised by an unusual relative abundance of 17O, distinct from that associated with cloud-derived, synoptic snowfall. Furthermore, this distinction appears to be largely preserved in the ice core record. The respective mass contributions to snowfall accumulation - on both temporal and spatial scales - provides the basis of a simple, first-order explanation for the observed oxygen triple-isotope ratio variations in Antarctic precipitation, surface snow and ice cores. Using this approach, it is shown that precipitation during the last major deglaciation, both in western Antarctica at the West Antarctic Ice Sheet (WAIS) Divide and at Vostok on the eastern Antarctic plateau, consisted essentially of diamond dust only, despite a large temperature differential (and thus different water vapour supersaturation conditions) at the two locations. In contrast, synoptic snowfall events dominate the accumulation record throughout the Holocene at both sites.

Invited review: climate change impacts in polar regions: lessons from Antarctic moss bank archives.

Science.gov (United States)

Royles, Jessica; Griffiths, Howard

2015-03-01

Mosses are the dominant plants in polar and boreal regions, areas which are experiencing rapid impacts of regional warming. Long-term monitoring programmes provide some records of the rate of recent climate change, but moss peat banks contain an unrivalled temporal record of past climate change on terrestrial plant Antarctic systems. We summarise the current understanding of climatic proxies and determinants of moss growth for contrasting continental and maritime Antarctic regions, as informed by 13C and 18O signals in organic material. Rates of moss accumulation are more than three times higher in the maritime Antarctic than continental Antarctica with growing season length being a critical determinant of growth rate, and high carbon isotope discrimination values reflecting optimal hydration conditions. Correlation plots of 13C and 18O values show that species (Chorisodontium aciphyllum / Polytrichum strictum) and growth form (hummock / bank) are the major determinants of measured isotope ratios. The interplay between moss growth form, photosynthetic physiology, water status and isotope composition are compared with developments of secondary proxies, such as chlorophyll fluorescence. These approaches provide a framework to consider the potential impact of climate change on terrestrial Antarctic habitats as well as having implications for future studies of temperate, boreal and Arctic peatlands. There are many urgent ecological and environmental problems in the Arctic related to mosses in a changing climate, but the geographical ranges of species and life-forms are difficult to track individually. Our goal was to translate what we have learned from the more simple systems in Antarctica, for application to Arctic habitats. © 2014 John Wiley & Sons Ltd.

Morphological variation and taxonomic interpretation in the moss genus Bryum in Antarctica

OpenAIRE

Seppelt,Rodney D.; Kanda,Hiroshi

1986-01-01

The potential for morphological variation in Antarctic species of Bryum is evaluated and related to problems associated with taxonomic interpretation based on specimens from the Soya Coast, Mac. Robertson Coast, Vestfold Hills and Knox Coast. B. argenteum HEDW. Has been positively determined for Continental Antarctica from six localities on the Soya Coast and from Ross Island, southern Victoria Land. Specimens from the Vestfold Hills and Knox Coast considered with some reservation as this spe...

Increase in penguin populations during the Little Ice Age in the Ross Sea, Antarctica.

Science.gov (United States)

Hu, Qi-Hou; Sun, Li-Guang; Xie, Zhou-Qing; Emslie, Steven D; Liu, Xiao-Dong

2013-01-01

Penguins are an important seabird species in Antarctica and are sensitive to climate and environmental changes. Previous studies indicated that penguin populations increased when the climate became warmer and decreased when it became colder in the maritime Antarctic. Here we determined organic markers in a sediment profile collected at Cape Bird, Ross Island, high Antarctic, and reconstructed the history of Adélie penguin colonies at this location over the past 700 years. The region transformed from a seal to a penguin habitat when the Little Ice Age (LIA; 1500-1800 AD) began. Penguins then became the dominant species. Penguin populations were the highest during ca. 1490 to 1670 AD, a cold period, which is contrary to previous results in other regions much farther north. Different responses to climate change may occur at low latitudes and high latitudes in the Antarctic, even if for same species.

Climate Proxies: An Inquiry-Based Approach to Discovering Climate Change on Antarctica

Science.gov (United States)

Wishart, D. N.

2016-12-01

An attractive way to advance climate literacy in higher education is to emphasize its relevance while teaching climate change across the curriculum to science majors and non-science majors. An inquiry-based pedagogical approach was used to engage five groups of students on a "Polar Discovery Project" aimed at interpreting the paleoclimate history of ice cores from Antarctica. Learning objectives and student learning outcomes were clearly defined. Students were assigned several exercises ranging from examination of Antarctic topography to the application of physical and chemical measurements as proxies for climate change. Required materials included base and topographic maps of Antarctica; graph sheets for construction of topographic cross-sectional profiles from profile lines of the Western Antarctica Ice Sheet (WAIS) Divide and East Antarctica; high-resolution photographs of Antarctic ice cores; stratigraphic columns of ice cores; borehole and glaciochemical data (i.e. anions, actions, δ18O, δD etc.); and isotope data on greenhouse gases (CH4, O2, N2) extracted from gas bubbles in ice cores. The methodology was to engage students in (2) construction of topographic profiles; (2) suggest directions for ice flow based on simple physics; (3) formulate decisions on suitable locations for drilling ice cores; (4) visual ice stratigraphy including ice layer counting; (5) observation of any insoluble particles (i.e. meteoritic and volcanic material); (6) analysis of borehole temperature profiles; and (7) the interpretation of several datasets to derive a paleoclimate history of these areas of the continent. The overall goal of the project was to improve the students analytical and quantitative skills; their ability to evaluate relationships between physical and chemical properties in ice cores, and to advance the understanding the impending consequences of climate change while engaging science, technology, engineering and mathematics (STEM). Student learning outcomes

Crustal thickness of Antarctica estimated using data from gravimetric satellites

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M. Llubes

2018-04-01

Full Text Available Computing a better crustal thickness model is still a necessary improvement in Antarctica. In this remote continent where almost all the bedrock is covered by the ice sheet, seismic investigations do not reach a sufficient spatial resolution for geological and geophysical purposes. Here, we present a global map of Antarctic crustal thickness computed from space gravity observations. The DIR5 gravity field model, built from GOCE and GRACE gravimetric data, is inverted with the Parker–Oldenburg iterative algorithm. The BEDMAP products are used to estimate the gravity effect of the ice and the rocky surface. Our result is compared to crustal thickness calculated from seismological studies and the CRUST1.0 and AN1 models. Although the CRUST1.0 model shows a very good agreement with ours, its spatial resolution is larger than the one we obtain with gravimetric data. Finally, we compute a model in which the crust–mantle density contrast is adjusted to fit the Moho depth from the CRUST1.0 model. In East Antarctica, the resulting density contrast clearly shows higher values than in West Antarctica.

Coastal-Change and Glaciological Map of the Northern Ross Ice Shelf Area, Antarctica: 1962-2004

Science.gov (United States)

Ferrigno, Jane G.; Foley, Kevin M.; Swithinbank, Charles; Williams, Richard S.

2007-01-01

Programs. On the basis of these recommendations, the U.S. Geological Survey (USGS) decided that the archive of early 1970s Landsat 1, 2, and 3 Multispectral Scanner (MSS) images of Antarctica and the subsequent repeat coverage made possible with Landsat and other satellite images provided an excellent means of documenting changes in the coastline of Antarctica (Ferrigno and Gould, 1987). The availability of this information provided the impetus for carrying out a comprehensive analysis of the glaciological features of the coastal regions and changes in ice fronts of Antarctica (Swithinbank, 1988; Williams and Ferrigno, 1988). The project was later modified to include Landsat 4 and 5 MSS and Thematic Mapper (TM) images (and in some areas Landsat 7 Enhanced Thematic Mapper Plus [ETM+] images), RADARSAT images, and other data where available, in order to compare changes that occurred during a 20- to 25- or 30-year time interval (or longer where data were available, as in the Antarctic Peninsula). The results of the analysis are being used to produce a digital database and a series of USGS Geologic Investigations Series Maps (I?2600) (Williams and others, 1995; Williams and Ferrigno, 1998; Ferrigno and others, 2002) (available online at http://www.glaciers.er.usgs.gov).

How committed are we to monitoring human impacts in Antarctica?

OpenAIRE

Hughes, Kevin

2010-01-01

Under the Antarctic Treaty System, environmental monitoring is a legal obligation for signatory nations and an essential tool for managers attempting to minimize local human impacts, but is it given the importance it merits? Antarctica is a vast frozen continent with an area around 1.5 times that of Europe (14 000 000 km2), but the majority of its terrestrial life is found on multiple outcrops or 'islands' of ice-free coastal ground, with a combined area of ~6000 km2, equivalent to four t...

Mars weathering analogs - Secondary mineralization in Antarctic basalts

Science.gov (United States)

Berkley, J. L.

1982-01-01

Alkalic basalt samples from Ross Island, Antarctica, are evaluated as terrestrial analogs to weathered surface materials on Mars. Secondary alteration in the rocks is limited to pneumatolytic oxidation of igneous minerals and glass, rare groundmass clay and zeolite mineralization, and hydrothermal minerals coating fractures and vesicle surfaces. Hydrothermal mineral assemblages consist mainly of K-feldspar, zeolites (phillipsite and chabazite), calcite, and anhydrite. Low alteration rates are attributed to cold and dry environmental factors common to both Antarctica and Mars. It is noted that mechanical weathering (aeolian abrasion) of Martian equivalents to present Antarctic basalts would yield minor hydrothermal minerals and local surface fines composed of primary igneous minerals and glass but would produce few hydrous products, such as palagonite, clay or micas. It is thought that leaching of hydrothermal vein minerals by migrating fluids and redeposition in duricrust deposits may represent an alternate process for incorporating secondary minerals of volcanic origin into Martian surface fines.

Antarctic climate and ice-sheet configuration during the early Pliocene interglacial at 4.23 Ma

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N. R. Golledge

2017-07-01

Full Text Available The geometry of Antarctic ice sheets during warm periods of the geological past is difficult to determine from geological evidence, but is important to know because such reconstructions enable a more complete understanding of how the ice-sheet system responds to changes in climate. Here we investigate how Antarctica evolved under orbital and greenhouse gas conditions representative of an interglacial in the early Pliocene at 4.23 Ma, when Southern Hemisphere insolation reached a maximum. Using offline-coupled climate and ice-sheet models, together with a new synthesis of high-latitude palaeoenvironmental proxy data to define a likely climate envelope, we simulate a range of ice-sheet geometries and calculate their likely contribution to sea level. In addition, we use these simulations to investigate the processes by which the West and East Antarctic ice sheets respond to environmental forcings and the timescales over which these behaviours manifest. We conclude that the Antarctic ice sheet contributed 8.6 ± 2.8 m to global sea level at this time, under an atmospheric CO2 concentration identical to present (400 ppm. Warmer-than-present ocean temperatures led to the collapse of West Antarctica over centuries, whereas higher air temperatures initiated surface melting in parts of East Antarctica that over one to two millennia led to lowering of the ice-sheet surface, flotation of grounded margins in some areas, and retreat of the ice sheet into the Wilkes Subglacial Basin. The results show that regional variations in climate, ice-sheet geometry, and topography produce long-term sea-level contributions that are non-linear with respect to the applied forcings, and which under certain conditions exhibit threshold behaviour associated with behavioural tipping points.

Relative motions of the Australian, Pacific and Antarctic plates estimated by the Global Positioning System

Science.gov (United States)

Larson, Kristine M.; Freymueller, Jeff

1995-01-01

Global Positioning System (GPS) measurements spanning approximately 3 years have been used to determine velocities for 7 sites on the Australian, Pacific and Antarctic plates. The site velocities agree with both plate model predictions and other space geodetic techniques. We find no evidence for internal deformation of the interior of the Australian plate. Wellington, New Zealand, located in the Australian-Pacific plate boundary zone, moves 20 +/- 5 mm/yr west-southwest relative to the Australian plate. Its velocity lies midway between the predicted velocities of the two plates. Relative Euler vectors for the Australia-Antarctica and Pacific-Antarctica plates agree within one standard deviation with the NUVEL-1A predictions.

Genetic signature of Last Glacial Maximum regional refugia in a circum-Antarctic sea spider

Science.gov (United States)

Soler-Membrives, Anna; Linse, Katrin; Miller, Karen J.; Arango, Claudia P.

2017-10-01

The evolutionary history of Antarctic organisms is becoming increasingly important to understand and manage population trajectories under rapid environmental change. The Antarctic sea spider Nymphon australe, with an apparently large population size compared with other sea spider species, is an ideal target to look for molecular signatures of past climatic events. We analysed mitochondrial DNA of specimens collected from the Antarctic continent and two Antarctic islands (AI) to infer past population processes and understand current genetic structure. Demographic history analyses suggest populations survived in refugia during the Last Glacial Maximum. The high genetic diversity found in the Antarctic Peninsula and East Antarctic (EA) seems related to multiple demographic contraction-expansion events associated with deep-sea refugia, while the low genetic diversity in the Weddell Sea points to a more recent expansion from a shelf refugium. We suggest the genetic structure of N. australe from AI reflects recent colonization from the continent. At a local level, EA populations reveal generally low genetic differentiation, geographically and bathymetrically, suggesting limited restrictions to dispersal. Results highlight regional differences in demographic histories and how these relate to the variation in intensity of glaciation-deglaciation events around Antarctica, critical for the study of local evolutionary processes. These are valuable data for understanding the remarkable success of Antarctic pycnogonids, and how environmental changes have shaped the evolution and diversification of Southern Ocean benthic biodiversity.

The contents and distributions of cadmium, mercury, and lead in Usnea antarctica lichens from Solorina Valley, James Ross Island (Antarctica).

Science.gov (United States)

Zvěřina, Ondřej; Coufalík, Pavel; Barták, Miloš; Petrov, Michal; Komárek, Josef

2017-12-11

Lichens are efficient and cost-effective biomonitors of the environment. Their geographic distribution together with their slow growth rate enable investigation of the deposition patterns of various elements and substances. In this research, levels of cadmium, lead, and mercury in Usnea antarctica lichens in the area of James Ross Island, Antarctica, were investigated. The lichens were microwave-digested, and the metals were determined by means of atomic absorption spectrometry with graphite furnace and a direct mercury analyzer. Median total contents of Cd, Hg, and Pb were 0.04, 0.47, and 1.6 mg/kg in whole lichens, respectively. The bottom-up distributions of these metals in the fruticose lichen thalli were investigated, and it was revealed that the accumulation patterns for mercury and lead were opposite to that for cadmium. The probable reason for this phenomenon may lie in the inner structure of thalli. The total contents of metals were comparable with those published for other unpolluted areas of maritime Antarctica. However, this finding was not expected for mercury, since the sampling locality was close to an area with some of the highest mercury contents published for Antarctic lichens. In short, lichens proved their usability as biological monitors, even in harsh conditions. However, the findings emphasize the need to take into account the distributions of elements both in the environment and in the lichen itself.

Meteorological observatory for Antarctic data collection; L`Osservatorio per l`acquisizione dei dati meteorologici in Antartide

Energy Technology Data Exchange (ETDEWEB)

Grigioni, P.; De silvestri, L. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dip. Ambiente; Della Vedova, A.M. [Istituto Nazionale di Geofisica, P.N.R.A., Rome (Italy)

1996-12-31

In the last years, a great number of automatic weather stations was installed in Antarctica, with the aim to examine closely the weather and climate of this region and to improve the coverage of measuring points on the Antarctic surface. In 1987 the Italian Antarctic Project started to set up a meteorological network, in an area not completely covered by other countries. Some of the activities performed by the meteorological observatory, concerning technical functions such as maintenance of the AWS`s and the execution of radio soundings, or relating to scientific purposes such as validation and elaboration of collected data, are exposed. Finally, some climatological considerations on the thermal behaviour of the Antarctic troposphere such as `coreless winter`, and on the wind field, including katabatic flows in North Victoria Land are described.

77 FR 35431 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

Science.gov (United States)

2012-06-13

... activities in Antarctica and designation of certain animals and certain geographic areas a requiring special... Weddell seals, a prominent Antarctic apex predator associated with fast ice, has been intensively studied..., then released. In addition, the applicant plans to salvage parts of dead animals encountered and remove...

Trace metals in Antarctica related to climate change and increasing human impact.

Science.gov (United States)

Bargagli, R

2000-01-01

Metals are natural constituents of the abiotic and biotic components of all ecosystems, and under natural conditions they are cycled within and between the geochemical spheres--the atmosphere, lithosphere, hydrosphere, and biosphere--at quite steady fluxes. In the second half of the twentieth century, the huge increase in energy and mineral consumption determined anthropogenic emissions of several metals exceeding those from natural sources, e.g., volcanoes and windborne soil particles. In the Northern Hemisphere, the biogeochemical cycles of Pb, Cd, Zn, Cu, and other metals were significantly altered, even in Arctic regions. On the contrary, available data on trace metal concentrations in abiotic matrices from continental Antarctica, summarized in this review, suggest that the biogeochemical cycle of Pb is probably the only one that has been significantly altered by anthropogenic emissions in Antarctica and elsewhere in the Southern Hemisphere, especially in the period 1950-1975. Environmental contamination by other metals from anthropogenic sources in Antarctica itself can generally only be detected in snow samples taken within a range of a few kilometers or several hundred meters from scientific stations. Local metal pollution from human activities in Antarctica may compromise studies aimed at assessing the biogeochemical cycle of trace elements and the effects of global climate change. Thus, this review focuses on concentrations of metals in atmospheric particulate, snow, surface soils, and freshwater from the Antarctic continent and surface sediments and seawater from the Southern Ocean, which can plausibly be regarded as global background values of trace elements. These baselines are also necessary in view of the construction of new stations, the expansion of existing facilities to support research, and the growth of tourism and fisheries. Despite difficulties in making comparisons with data from other remote areas of the world, concentrations of trace metals

A multivariate analysis of Antarctic sea ice since 1979

Energy Technology Data Exchange (ETDEWEB)

Magalhaes Neto, Newton de; Evangelista, Heitor [Universidade do Estado do Rio de Janeiro (Uerj), LARAMG - Laboratorio de Radioecologia e Mudancas Globais, Maracana, Rio de Janeiro, RJ (Brazil); Tanizaki-Fonseca, Kenny [Universidade do Estado do Rio de Janeiro (Uerj), LARAMG - Laboratorio de Radioecologia e Mudancas Globais, Maracana, Rio de Janeiro, RJ (Brazil); Universidade Federal Fluminense (UFF), Dept. Analise Geoambiental, Inst. de Geociencias, Niteroi, RJ (Brazil); Penello Meirelles, Margareth Simoes [Universidade do Estado do Rio de Janeiro (UERJ)/Geomatica, Maracana, Rio de Janeiro, RJ (Brazil); Garcia, Carlos Eiras [Universidade Federal do Rio Grande (FURG), Laboratorio de Oceanografia Fisica, Rio Grande, RS (Brazil)

2012-03-15

Recent satellite observations have shown an increase in the total extent of Antarctic sea ice, during periods when the atmosphere and oceans tend to be warmer surrounding a significant part of the continent. Despite an increase in total sea ice, regional analyses depict negative trends in the Bellingshausen-Amundsen Sea and positive trends in the Ross Sea. Although several climate parameters are believed to drive the formation of Antarctic sea ice and the local atmosphere, a descriptive mechanism that could trigger such differences in trends are still unknown. In this study we employed a multivariate analysis in order to identify the response of the Antarctic sea ice with respect to commonly utilized climate forcings/parameters, as follows: (1) The global air surface temperature, (2) The global sea surface temperature, (3) The atmospheric CO{sub 2} concentration, (4) The South Annular Mode, (5) The Nino 3, (6) The Nino (3 + 4, 7) The Nino 4, (8) The Southern Oscillation Index, (9) The Multivariate ENSO Index, (10) the Total Solar Irradiance, (11) The maximum O{sub 3} depletion area, and (12) The minimum O{sub 3} concentration over Antarctica. Our results indicate that western Antarctic sea ice is simultaneously impacted by several parameters; and that the minimum, mean, and maximum sea ice extent may respond to a separate set of climatic/geochemical parameters. (orig.)

Aerobiology Over Antarctica - A New Initiative for Atmospheric Ecology.

Science.gov (United States)

Pearce, David A; Alekhina, Irina A; Terauds, Aleks; Wilmotte, Annick; Quesada, Antonio; Edwards, Arwyn; Dommergue, Aurelien; Sattler, Birgit; Adams, Byron J; Magalhães, Catarina; Chu, Wan-Loy; Lau, Maggie C Y; Cary, Craig; Smith, David J; Wall, Diana H; Eguren, Gabriela; Matcher, Gwynneth; Bradley, James A; de Vera, Jean-Pierre; Elster, Josef; Hughes, Kevin A; Cuthbertson, Lewis; Benning, Liane G; Gunde-Cimerman, Nina; Convey, Peter; Hong, Soon Gyu; Pointing, Steve B; Pellizari, Vivian H; Vincent, Warwick F

2016-01-01

The role of aerial dispersal in shaping patterns of biodiversity remains poorly understood, mainly due to a lack of coordinated efforts in gathering data at appropriate temporal and spatial scales. It has been long known that the rate of dispersal to an ecosystem can significantly influence ecosystem dynamics, and that aerial transport has been identified as an important source of biological input to remote locations. With the considerable effort devoted in recent decades to understanding atmospheric circulation in the south-polar region, a unique opportunity has emerged to investigate the atmospheric ecology of Antarctica, from regional to continental scales. This concept note identifies key questions in Antarctic microbial biogeography and the need for standardized sampling and analysis protocols to address such questions. A consortium of polar aerobiologists is established to bring together researchers with a common interest in the airborne dispersion of microbes and other propagules in the Antarctic, with opportunities for comparative studies in the Arctic.

On the Atmospheric Correction of Antarctic Airborne Hyperspectral Data

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Martin Black

2014-05-01

Full Text Available The first airborne hyperspectral campaign in the Antarctic Peninsula region was carried out by the British Antarctic Survey and partners in February 2011. This paper presents an insight into the applicability of currently available radiative transfer modelling and atmospheric correction techniques for processing airborne hyperspectral data in this unique coastal Antarctic environment. Results from the Atmospheric and Topographic Correction version 4 (ATCOR-4 package reveal absolute reflectance values somewhat in line with laboratory measured spectra, with Root Mean Square Error (RMSE values of 5% in the visible near infrared (0.4–1 µm and 8% in the shortwave infrared (1–2.5 µm. Residual noise remains present due to the absorption by atmospheric gases and aerosols, but certain parts of the spectrum match laboratory measured features very well. This study demonstrates that commercially available packages for carrying out atmospheric correction are capable of correcting airborne hyperspectral data in the challenging environment present in Antarctica. However, it is anticipated that future results from atmospheric correction could be improved by measuring in situ atmospheric data to generate atmospheric profiles and aerosol models, or with the use of multiple ground targets for calibration and validation.

Isolation and Characterization of Phenanthrene Degrading Bacteria from Diesel Fuel-Contaminated Antarctic Soils

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Alejandro Gran-Scheuch

2017-08-01

Full Text Available Antarctica is an attractive target for human exploration and scientific investigation, however the negative effects of human activity on this continent are long lasting and can have serious consequences on the native ecosystem. Various areas of Antarctica have been contaminated with diesel fuel, which contains harmful compounds such as heavy metals and polycyclic aromatic hydrocarbons (PAH. Bioremediation of PAHs by the activity of microorganisms is an ecological, economical, and safe decontamination approach. Since the introduction of foreign organisms into the Antarctica is prohibited, it is key to discover native bacteria that can be used for diesel bioremediation. By following the degradation of the PAH phenanthrene, we isolated 53 PAH metabolizing bacteria from diesel contaminated Antarctic soil samples, with three of these isolates exhibiting a high phenanthrene degrading capacity. In particular, the Sphingobium xenophagum D43FB isolate showed the highest phenanthrene degradation ability, generating up to 95% degradation of initial phenanthrene. D43FB can also degrade phenanthrene in the presence of its usual co-pollutant, the heavy metal cadmium, and showed the ability to grow using diesel-fuel as a sole carbon source. Microtiter plate assays and SEM analysis revealed that S. xenophagum D43FB exhibits the ability to form biofilms and can directly adhere to phenanthrene crystals. Genome sequencing analysis also revealed the presence of several genes involved in PAH degradation and heavy metal resistance in the D43FB genome. Altogether, these results demonstrate that S. xenophagum D43FB shows promising potential for its application in the bioremediation of diesel fuel contaminated-Antarctic ecosystems.

Is there a distinct continental slope fauna in the Antarctic?

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Kaiser, Stefanie; Griffiths, Huw J.; Barnes, David K. A.; Brandão, Simone N.; Brandt, Angelika; O'Brien, Philip E.

2011-02-01

The Antarctic continental slope spans the depths from the shelf break (usually between 500 and 1000 m) to ˜3000 m, is very steep, overlain by 'warm' (2-2.5 °C) Circumpolar Deep Water (CDW), and life there is poorly studied. This study investigates whether life on Antarctica's continental slope is essentially an extension of the shelf or the abyssal fauna, a transition zone between these or clearly distinct in its own right. Using data from several cruises to the Weddell Sea and Scotia Sea, including the ANDEEP (ANtarctic benthic DEEP-sea biodiversity, colonisation history and recent community patterns) I-III, BIOPEARL (BIOdiversity, Phylogeny, Evolution and Adaptive Radiation of Life in Antarctica) 1 and EASIZ (Ecology of the Antarctic Sea Ice Zone) II cruises as well as current databases (SOMBASE, SCAR-MarBIN), four different taxa were selected (i.e. cheilostome bryozoans, isopod and ostracod crustaceans and echinoid echinoderms) and two areas, the Weddell Sea and the Scotia Sea, to examine faunal composition, richness and affinities. The answer has important ramifications to the link between physical oceanography and ecology, and the potential of the slope to act as a refuge and resupply zone to the shelf during glaciations. Benthic samples were collected using Agassiz trawl, epibenthic sledge and Rauschert sled. By bathymetric definition, these data suggest that despite eurybathy in some of the groups examined and apparent similarity of physical conditions in the Antarctic, the shelf, slope and abyssal faunas were clearly separated in the Weddell Sea. However, no such separation of faunas was apparent in the Scotia Sea (except in echinoids). Using a geomorphological definition of the slope, shelf-slope-abyss similarity only changed significantly in the bryozoans. Our results did not support the presence of a homogenous and unique Antarctic slope fauna despite a high number of species being restricted to the slope. However, it remains the case that there may be

Permafrost warming and vegetation changes in continental Antarctica

International Nuclear Information System (INIS)

Guglielmin, Mauro; Dalle Fratte, Michele; Cannone, Nicoletta

2014-01-01

Continental Antarctica represents the last pristine environment on Earth and is one of the most suitable contexts to analyze the relations between climate, active layer and vegetation. In 2000 we started long-term monitoring of the climate, permafrost, active layer and vegetation in Victoria Land, continental Antarctica. Our data confirm the stability of mean annual and summer air temperature, of snow cover, and an increasing trend of summer incoming short wave radiation. The active layer thickness is increasing at a rate of 0.3 cm y −1 . The active layer is characterized by large annual and spatial differences. The latter are due to scarce vegetation, a patchy and very thin organic layer and large spatial differences in snow accumulation. The active layer thickening, probably due to the increase of incoming short wave radiation, produced a general decrease of the ground water content due to the better drainage of the ground. The resultant drying may be responsible for the decline of mosses in xeric sites, while it provided better conditions for mosses in hydric sites, following the species-specific water requirements. An increase of lichen vegetation was observed where the climate drying occurred. This evidence emphasizes that the Antarctic continent is experiencing changes that are in total contrast to the changes reported from maritime Antarctica. (paper)

Carbon isotope geothermometry of graphite-bearing marbles from Central Dronning Maud Land, East Antarctica

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Wand, U.; Muehle, K.

1988-01-01

In order to estimate the peak metamorphic temperatures in high-grade regional metamorphic marbles from central Dronning Maud Land (East Antarctica), 13 C/ 12 C isotope ratios have been measured for coexisting carbonate and graphite pairs. The δ 13 C values of carbonates (calcite ± dolomite) and graphite vary from -0.1 to +4.6 permill (PDB) and from -3.3 to +1.7 permill, respectively. The isotopic fractionation between carbonate and graphite ranges from 2.9 to 4.0 permill and is similar to the Δ 13 C (carb-gr) values observed in other East Antarctic and non-Antarctic granulite-facies marbles. The metamorphic temperatures calculated using the equation of VALLEY and O'NEIL (1981) for calcite-graphite pairs are predominantly in the range 700 0 - 800 0 C (x n=5 ± s = 730 0 ± 30 0 C) and agree well with metamorphic temperatures derived from mineral chemical studies in this East Antarctic region. (author)

Kiloniella antarctica sp. nov., isolated from a polynya of Amundsen Sea in Western Antarctic Sea.

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Si, Ok-Ja; Yang, Hye-Young; Hwang, Chung Yeon; Kim, So-Jeong; Choi, Sun-Bin; Kim, Jong-Geol; Jung, Man-Young; Kim, Song-Gun; Roh, Seong Woon; Rhee, Sung-Keun

2017-07-01

A taxonomic study was conducted on strain soj2014T, which was isolated from the surface water of a polynya in the Antarctic Sea. Comparative 16S rRNA gene sequence analysis showed that strain soj2014T belongs to the family Kiloniellaceae and is closely related to Kiloniella spongiae MEBiC09566T, 'Kiloniella litopenaei' P1-1T and Kiloniella laminariae LD81T (98.0 %, 97.8 % and 96.2 % 16S rRNA gene sequence similarity, respectively). The DNA-DNA hybridization values between strain soj2014T and closely related strains were below 28.6 %. The G+C content of the genomic DNA of strain soj2014T was 45.5 mol%. The predominant cellular fatty acids were summed feature 8 (composed of C18 : 1ω6c/C18 : 1ω7c, 57.0 %) and summed feature 3 (composed of C16 : 1ω6c/C16 : 1ω7c, 23.5 %). Strain soj2014T was Gram-stain-negative, slightly curved, spiral-shaped, and motile with a single polar flagellum. The strain grew at 0-30 °C (optimum, 25 °C), in 1.5-5.1 % (w/v) NaCl (optimum, 2.1-2.4 %) and at pH 5.5-9.5 (optimum, 7.5-8.0). It also had differential carbohydrate utilization traits and enzyme activities compared with closely related strains. Based on these phylogenetic, phenotypic and chemotaxonomic analyses, strain soj2014T represents a distinct species, separable from the reference strains, and is, therefore, proposed as a novel species, Kiloniella antarctica sp. nov. The type strain is soj2014T (=KCTC 42186T=JCM 30386T).

Seismic Investigations of the Crust and Upper Mantle Structure in Antarctica and Madagascar

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Ramirez, Cristo

In the three studies that form this dissertation, seismic data from Antarctica and Madagascar have been analyzed to obtain new insights into crustal structure and mantle flow. Until recently, there have been little seismic data available from these areas for interrogating Earth structure and processes. In Antarctica, I analyzed datasets from temporary deployments of broadband seismic stations in both East and West Antarctica. In Madagascar, I analyzed data from a temporary network of broadband stations, along with data from three permanent stations. The seismic data have been processed and modeled using a wide range of techniques to characterize crust and mantle structure. Crustal structure in the East Antarctic Craton resembles Precambrian terrains around the world in its thickness and shear wave velocities. The West Antarctic Rift System has thinner crust, consistent with crustal thickness beneath other Cretaceous rifts. The Transantarctic Mountains show thickening of the crust from the costal regions towards the interior of the mountain range, and high velocities in the lower crust at several locations, possibly resulting from the Ferrar magmatic event. Ross Island and Marie Byrd Land Dome have elevated crustal Vp/Vs ratios, suggesting the presence of partial melt and/or volcaniclastic material within the crust. The pattern of seismic anisotropy in Madagascar is complex and cannot arise solely due to mantle flow from the African superplume, as previously proposed. To explain the complex pattern of anisotropy, a combination of mechanisms needs to be invoked, including mantle flow from the African superplume, mantle flow from the Comoros hotspot, small scale upwelling in the mantle induced by lithospheric delamination, and fossil anisotropy in the lithospheric mantle along Precambrian shear zones.

The origin of platyrrhines: An evaluation of the Antarctic scenario and the floating island model.

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Houle, A

1999-08-01

This paper evaluates whether 1) protoplatyrrhines could have migrated to South America via Antarctica, and 2) the floating island model is a plausible transoceanic mode of dispersal for land vertebrates like protoplatyrrhines. Results show that Eocene Antarctica and Australia supported large and dense forests, and that the Antarctic fauna was comprised of many species of vertebrates, including placental and marsupial land mammals. However, no primate remains have ever been reported from these continents. Antarctica and South America were connected until the Middle Eocene (i.e., after the oldest Asian anthropoids), but two major water barriers existed between Antarctica and Asia since the Early Eocene. The Eocene and Oligocene water gap separating Africa and Antarctica was excessively large. Thus, all scenarios involving an Antarctic route have been rejected. The African scenario is difficult to falsify because only one water barrier existed, both paleowinds and paleocurrents were favorable, and Paleogene African anthropoids show phylogenetic affinities to platyrrhines. I tested whether a journey on a hypothetical floating island over the Paleogene Atlantic Ocean exceeds the survival limit of a genetically viable group of animals such as protoplatyrrhines. Studies of water deprivation suggest that they could have been able, with a body weight averaging 1 kg, to survive without water for at least 13 days. I have used the present Atlantic Ocean as a model for the velocity of Paleogene paleowinds and paleocurrents. Considering winds as the key accelerating force of floating islands, the Paleogene Atlantic water barrier could have been crossed, in the most conservative scenario, in 8 days at 50 Mya, 11 days at 40 Mya, and 15 days at 30 Mya. In order to survive a transoceanic journey, however, protoplatyrrhines had to be preadapted to strong seasonal variations in water availability in their original (African) environment. Once on the sea, their brains would have

Monitoring of Antarctic moss ecosystems using a high spatial resolution imaging spectroscopy

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Malenovsky, Zbynek; Lucieer, Arko; Robinson, Sharon; Harwin, Stephen; Turner, Darren; Veness, Tony

2013-04-01

The most abundant photosynthetically active plants growing along the rocky Antarctic shore are mosses of three species: Schistidium antarctici, Ceratodon purpureus, and Bryum pseudotriquetrum. Even though mosses are well adapted to the extreme climate conditions, their existence in Antarctica depends strongly on availability of liquid water from snowmelt during the short summer season. Recent changes in temperature, wind speed and stratospheric ozone are stimulating faster evaporation, which in turn influences moss growing rate, health state and abundance. This makes them an ideal bio-indicator of the Antarctic climate change. Very short growing season, lasting only about three months, requires a time efficient, easily deployable and spatially resolved method for monitoring the Antarctic moss beds. Ground and/or low-altitude airborne imaging spectroscopy (called also hyperspectral remote sensing) offers a fast and spatially explicit approach to investigate an actual spatial extent and physiological state of moss turfs. A dataset of ground-based spectral images was acquired with a mini-Hyperspec imaging spectrometer (Headwall Inc., the USA) during the Antarctic summer 2012 in the surroundings of the Australian Antarctic station Casey (Windmill Islands). The collection of high spatial resolution spectral images, with pixels about 2 cm in size containing from 162 up to 324 narrow spectral bands of wavelengths between 399 and 998 nm, was accompanied with point moss reflectance measurements recorded with the ASD HandHeld-2 spectroradiometer (Analytical Spectral Devices Inc., the USA). The first spectral analysis indicates significant differences in red-edge and near-infrared reflectance of differently watered moss patches. Contrary to high plants, where the Normalized Difference Vegetation Index (NDVI) represents an estimate of green biomass, NDVI of mosses indicates mainly the actual water content. Similarly to high plants, reflectance of visible wavelengths is

Contrasting patterns in lichen diversity in the continental and maritime Antarctic

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Singh, Shiv Mohan; Olech, Maria; Cannone, Nicoletta; Convey, Peter

2015-09-01

Systematic surveys of the lichen floras of Schirmacher Oasis (Queen Maud Land, continental Antarctic), Victoria Land (Ross Sector, continental Antarctic) and Admiralty Bay (South Shetland Islands, maritime Antarctic) were compared to help infer the major factors influencing patterns of diversity and biogeography in the three areas. Biogeographic patterns were determined using a variety of multivariate statistical tools. A total of 54 lichen species were documented from Schirmacher Oasis (SO), 48 from Victoria Land (VL) and 244 from Admiralty Bay (AB). Of these, 21 species were common to all areas. Most lichens from the SO and VL areas were microlichens, the dominant genus being Buellia. In AB, in contrast, many macrolichens were also present and the dominant genus was Caloplaca. In SO and VL large areas lacked any visible lichen cover, even where the ground was snow-free in summer. Small-scale diversity patterns were present in AB, where the number of species and genera was greater close to the coast. Most species recorded were rare in the study areas in which they were present and endemic to Antarctica.

Persistent organic pollutants (POPs) in the atmosphere of coastal areas of the Ross Sea, Antarctica: Indications for long-term downward trends.

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Pozo, Karla; Martellini, Tania; Corsolini, Simonetta; Harner, Tom; Estellano, Victor; Kukučka, Petr; Mulder, Marie D; Lammel, Gerhard; Cincinelli, Alessandra

2017-07-01

Passive air samplers were used to evaluate long-term trends and spatial distribution of trace organic compounds in Antarctica. Duplicate PUF disk samplers were deployed at six automatic weather stations in the coastal area of the Ross sea (East Antarctica), between December 2010 and January 2011, during the XXVI Italian Scientific Research Expedition. Among the investigated persistent organic compounds, Hexachlorobenzene was the most abundant, with air concentrations ranging from 0.8 to 50 pg m -3 . In general, the following decreasing concentration order was found for the air samples analyzed: HCB > PeCB > PCBs > DDTs > HCHs. While HCB concentrations were in the same range as those reported in the atmosphere of other Antarctic sampling areas and did not show a decline, HCHs and DDTs levels were lower or similar to those determined one or two decades ago. In general, the very low concentrations reflected the pristine state of the East Antarctica air. Backward trajectories indicated the prevalence of air masses coming from the Antarctic continent. Local contamination and volatilization from ice were suggested as potential sources for the presence of persistent organic pollutants in the atmosphere. Copyright © 2017 Elsevier Ltd. All rights reserved.

Distributional records of Antarctic fungi based on strains preserved in the Culture Collection of Fungi from Extreme Environments (CCFEE Mycological Section associated with the Italian National Antarctic Museum (MNA

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Laura Selbmann

2015-07-01

Full Text Available This dataset includes information regarding fungal strains collected during several Antarctic expeditions: the Italian National Antarctic Research program (PNRA expeditions “X” (1994/1995, “XII” (1996/1997, “XVII” (2001/2002, “XIX” (2003/2004, “XXVI” (2010/2011, the Czech “IPY Expedition” (2007–2009 and a number of strains donated by E. Imre Friedmann (Florida State University in 2001, isolated from samples collected during the U.S.A. Antarctic Expeditions of 1980-1982. Samples, consisting of colonized rocks, mosses, lichens, sediments and soils, were collected in Southern and Northern Victoria Land of the continental Antarctica and in the Antarctic Peninsula. A total of 259 different strains were isolated, belonging to 32 genera and 38 species, out of which 12 represented new taxa. These strains are preserved in the Antarctic section of the Culture Collection of Fungi from Extreme Environments (CCFEE, which represents one of the collections associated with the Italian National Antarctic Museum (MNA, Section of Genoa, Italy, located at the Laboratory of Systematic Botany and Mycology, Department of Ecological and Biological Sciences (DEB, Tuscia University (Viterbo, Italy. The CCFEE hosts a total of 486 Antarctic fungal strains from worldwide extreme environments. Distributional records are reported here for 259 of these strains. The holotypes of the 12 new species included in this dataset are maintained at CCFEE and in other international collections: CBS-KNAW Fungal Biodiversity Centre (Utrecht, Netherlands; DBVPG, Industrial Yeasts Collection (University of Perugia, Italy; DSMZ, German Collection of Microorganisms and Cell Cultures (Brunswick, Germany; IMI, International Mycological Institute (London, U.K..

Annually-resolved temperature reconstructions of the past 2000 years from Dome-Fuji, East Antarctica

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Motizuki, Yuko; Takahashi, Kazuya; Nakai, Yoichi; Motoyama, Hideaki

2016-04-01

We present annually-resolved temperature and SST reconstructions of the past 2000 years based on water (oxygen and deuterium) isotope measurement on a shallow ice core drilled in 2010 at Dome Fuji station, East Antarctica. These time series records will be an essential contribution to the PAGES 2k project from sparse data area in Antarctica. Dome Fuji station is located on a summit of Dronning Maud Land at an altitude of 3810 m a.s.l. (above sea level) (77o19'01'' S, 39o42'12'' E) in East Antarctica. The 10 m depth mean snow temperature at Dome Fuji is -57.3oC1). The inland area around Dome Fuji has been recognized to be especially unique: The snow and ice there contain much stratospheric information. The direct evidence for this comes from tritium contents originated from the nuclear bomb tests in the 1960s; the tritium fallout at the Dome Fuji site is outstandingly high among 16 snow pit samples widely collected over Antarctica2). To date the concerned Dome Fuji ice core, we applied volcanic signature matching to transfer the West Antarctic Ice Sheet (WAIS) Divide ice core chronology constructed by annual layer counting as used in the study by Sigl et al. (2014)3). In our presentation, we confine ourselves to discuss the oscillation periodicity that we observed in the oxygen isotope record in our data: The periods of approximately 10, 20, and 200 years were found. We will present the time series analyses for this in detail, and will discuss the origin of this periodicity. References: 1) Kameda, T., Motoyama, H., Fujita, S., and Takahashi, S.: "Past temporal and spatial variability of surface mass balance at Dome Fuji", East Antarctica, by the stake method from 1995 to 2006, J. Glaciol., 54, 107-116, 2008. 2) Fourre, E., Jean-Baptiste, P., Dapoigny, A., Baumier, D., Petit, J.-R., and Jouzel, J.: "Past and recent tritium levels in Arctic and Antarctic polar caps", Earth Planet. Sc. Lett., 245, 56-64, 2006. 3) Sigl, M., J. McConnell, M. Toohey, M. Curran, S. Das, R

Results of SPM sun photometer measurements at Mirny Antarctic station (58-60th RAE)

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Kabanov, Dmitry M.; Prakhov, Aleksander N.; Radionov, Vladimir F.; Sakerin, Sergey M.

2015-11-01

The SPM portable sun photometer observations in the wavelength range of 0.34-2.14 μm are performed at Mirny Antarctic station since fall 2013. The data obtained are used to calculate the aerosol optical depth (AOD) and water vapor content of the atmosphere. The sun photometer intercalibration results and statistical characteristics of interdiurnal and seasonal variations in spectral AOD of the atmosphere are discussed. Estimates of interannual variations in the atmospheric AOD in the region of Mirny station and in the coastal zone of Antarctica are presented. The global background level of AOD of the Antarctic atmosphere is noted to be still about 0.02 at the wavelength of 0.5 μm.

The infauna of three widely distributed sponge species (Hexactinellida and Demospongiae) from the deep Ekström Shelf in the Weddell Sea, Antarctica

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Kersken, Daniel; Göcke, Christian; Brandt, Angelika; Lejzerowicz, Franck; Schwabe, Enrico; Anna Seefeldt, Meike; Veit-Köhler, Gritta; Janussen, Dorte

2014-10-01

Due to their high abundance and large body size sponges have a central position in Antarctic zoobenthos, where they form the most extensive sponge grounds of the world. Though research on Antarctic benthos communities is quite established, research on sponge-associated infauna communities is scarce. We analyzed associated infauna of fifteen individuals of the sponge species Mycale (Oxymycale) acerata Kirkpatrick, 1907 (Demospongiae: Mycalina), Rossella antarctica Carter, 1872 and R. racovitzae Topsent, 1901 (both Hexactinellida: Lyssacinosida). Samples were collected from the deep Ekström Shelf at 602 m in the South-Eastern Weddell Sea, Antarctica, during the ANT XXIV-2 (SYSTCO I) expedition of RV Polarstern. The number of species, α- and β-diversity and the significantly different species composition of infauna communities related to sponge species were calculated, the latter via cluster analysis. The sponge-associated infauna consisted of five phyla: Foraminifera, Nematoda, Polychaeta, Mollusca and Arthropoda. In total 11,463 infaunal specimens were extracted and we found at least 76 associated species. Highest values of α-diversity were calculated for a sample of R. antarctica with a Shannon-Index of 1.84 and Simpson-Index of 0.72 respectively. Our results of the cluster-analysis show significant differences between infauna communities and a unique species composition for single sponge species. Polychaetes of the genus Syllis Lamarck, 1818 were numerous in M. acerata and genera like Pionosyllis Malmgren, 1867 and Cirratulus Lamarck, 1801 were numerous in R. antarctica. Individuals of the amphipod species Seba cf. dubia Schellenberg, 1926 were often found in R. antarctica and R. racovitzae while Colomastix fissilingua Schellenberg, 1926 was frequent in samples of M. acerata. Molluscs were present in M. acerata and R. antarctica but absent in R. racovitzae.

The ocean's role in polar climate change: asymmetric Arctic and Antarctic responses to greenhouse gas and ozone forcing.

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Marshall, John; Armour, Kyle C; Scott, Jeffery R; Kostov, Yavor; Hausmann, Ute; Ferreira, David; Shepherd, Theodore G; Bitz, Cecilia M

2014-07-13

In recent decades, the Arctic has been warming and sea ice disappearing. By contrast, the Southern Ocean around Antarctica has been (mainly) cooling and sea-ice extent growing. We argue here that interhemispheric asymmetries in the mean ocean circulation, with sinking in the northern North Atlantic and upwelling around Antarctica, strongly influence the sea-surface temperature (SST) response to anthropogenic greenhouse gas (GHG) forcing, accelerating warming in the Arctic while delaying it in the Antarctic. Furthermore, while the amplitude of GHG forcing has been similar at the poles, significant ozone depletion only occurs over Antarctica. We suggest that the initial response of SST around Antarctica to ozone depletion is one of cooling and only later adds to the GHG-induced warming trend as upwelling of sub-surface warm water associated with stronger surface westerlies impacts surface properties. We organize our discussion around 'climate response functions' (CRFs), i.e. the response of the climate to 'step' changes in anthropogenic forcing in which GHG and/or ozone-hole forcing is abruptly turned on and the transient response of the climate revealed and studied. Convolutions of known or postulated GHG and ozone-hole forcing functions with their respective CRFs then yield the transient forced SST response (implied by linear response theory), providing a context for discussion of the differing warming/cooling trends in the Arctic and Antarctic. We speculate that the period through which we are now passing may be one in which the delayed warming of SST associated with GHG forcing around Antarctica is largely cancelled by the cooling effects associated with the ozone hole. By mid-century, however, ozone-hole effects may instead be adding to GHG warming around Antarctica but with diminished amplitude as the ozone hole heals. The Arctic, meanwhile, responding to GHG forcing but in a manner amplified by ocean heat transport, may continue to warm at an accelerating rate.

Lichens as biomonitors with special reference to Antarctica

International Nuclear Information System (INIS)

Chipev, Nesho

2002-01-01

Lichens are effective biomonitors of metal deposition. Lichens are slow growing and assimilate metals at a rapid rate but release them at a low rate. Metal concentrations in lichen thalli have been shown to correlate with atmospheric levels. Lichens have been first used as bioaccumulative indicators in relation to point emission sources. Lichens have also been used to assess deposition patterns and heavy metal burdens for larger scale monitoring purposes. There are two problems to be kept in mind if lichens are to be effectively used as biomonitors. The first one is concerned with the chemical analyses. Results are more useful when background elemental levels are obtained. The choice of analytical method will depend on the purpose of the respective survey. Instrumental neutron activation analysis (INAA), atomic absorption spectrometry (AAS), Inductively coupled plasma emission spectrometry (ICP-ES) and epithermal neutron activation analysis (ENAA) are among the most commonly used methods. The second problem arises from the variability of lichens. Sources of variability include intra-individual variation, intra-species variation and variation due to microhabitat, locality or edaphic factors. Apart from individual variation, many of these sources of variation can be overcome by careful and thoughtful sampling and analysis of the selected species. Lichens and mosses are the only vegetation in Antarctica. The absence of air pollution in Antarctica suggests that lichens can be used as biomonitors of pollution at small scales around research bases. However, the unpolluted Antarctic environment presents opportunity for baseline studies on heavy metal bioaccumulation. Bioaccumulation in Antarctic lichens can allow a larger (global) scale insight into the airborne heavy metal circulation and deposition. Both high precision analytical methods and biological studies will be needed. (author)

Atmospheric Boundary Layer Dynamics Near Ross Island and Over West Antarctica.

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Liu, Zhong

The atmospheric boundary layer dynamics near Ross Island and over West Antarctica has been investigated. The study consists of two parts. The first part involved the use of data from ground-based remote sensing equipment (sodar and RASS), radiosondes, pilot balloons, automatic weather stations, and NOAA AVHRR satellite imagery. The second part involved the use of a high resolution boundary layer model coupled with a three-dimensional primitive equation mesoscale model to simulate the observed atmospheric boundary layer winds and temperatures. Turbulence parameters were simulated with an E-epsilon turbulence model driven by observed winds and temperatures. The observational analysis, for the first time, revealed that the airflow passing through the Ross Island area is supplied mainly by enhanced katabatic drainage from Byrd Glacier and secondarily drainage from Mulock and Skelton glaciers. The observed diurnal variation of the blocking effect near Ross Island is dominated by the changes in the upstream katabatic airflow. The synthesized analysis over West Antarctica found that the Siple Coast katabatic wind confluence zone consists of two superimposed katabatic airflows: a relatively warm and more buoyant katabatic flow from West Antarctica overlies a colder and less buoyant katabatic airflow from East Antarctica. The force balance analysis revealed that, inside the West Antarctic katabatic wind zone, the pressure gradient force associated with the blocked airflow against the Transantarctic Mountains dominates; inside the East Antarctic katabatic wind zone, the downslope buoyancy force due to the cold air overlying the sloping terrain is dominant. The analysis also shows that these forces are in geostrophic balance with the Coriolis force. An E-epsilon turbulence closure model is used to simulate the diurnal variation of sodar backscatter. The results show that the model is capable of qualitatively capturing the main features of the observed sodar backscatter. To

Retrospective biomonitoring of chemical contamination in the marine coastal environment of Terra Nova Bay (Ross Sea, Antarctica) by environmental specimen banking.

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Grotti, Marco; Pizzini, Sarah; Abelmoschi, Maria Luisa; Cozzi, Giulio; Piazza, Rossano; Soggia, Francesco

2016-12-01

Antarctica offers a good opportunity to investigate planetary-scale pollution and climate change, and provides baseline values for contaminants such as Trace Elements (TEs) and Persistent Organic Pollutants (POPs). Literature data on contaminant levels in the Antarctic environment indicate that long-range atmospheric transport is the primary pathway by which pollutants from surrounding continents are carried to this pristine environment. However, local contamination sources represented by the scientific stations are also not negligible. Climate change and global warming are altering the global budget of anthropogenic contaminants and their monitoring in Antarctica ecosystems is very important to protect the global environment. In this work, eighty specimens of Adamussium colbecki (Smith, 1902), a benthic Antarctic scallop, collected from 1996 to 2009 and stored in the Antarctic Environmental Specimen Bank, were analyzed to quantify TEs and POPs, including polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs) and polycyclic aromatic hydrocarbons (PAHs). Metals concentrations were not affected by anthropogenic contributions, highlighting a natural accumulation with the age of the organism. Similarly, no temporal trend was found for PCNs, PCBs and PAHs. However, specimens collected during the summer 1997-98 showed enhanced concentration levels of PCBs and PAHs that could refer to a local anthropogenic source of contamination. Copyright © 2016 Elsevier Ltd. All rights reserved.

Occurrence of arbuscular mycorrhizal fungi on King George Island, South Shetland Islands, Antarctica.

Science.gov (United States)

Barbosa, Marisângela V; Pereira, Elismara A; Cury, Juliano C; Carneiro, Marco A C

2017-01-01

Arbuscular mycorrhizal fungi make up an important ecological niche in ecosystems, and knowledge of their diversity in extreme environments is still incipient. The objective of this work was to evaluate the density and diversity of arbuscular mycorrhizal fungi in the soil of King George Island in the South Shetland Islands archipelago, Antarctica. For that, soil and roots of Deschampsia antarctica were collected at the brazilian research station in Antarctica. The spore density, species diversity and mycorrhizal colonization in the roots were evaluated. There was a low density of spores (27.4 ± 17.7) and root mycorrhizal colonization (6 ± 5.1%), which did not present statistical difference. Four species of arbuscular mycorrhizal fungi were identified, distributed in two genera: three species of the genus Glomus (Glomus sp1, Glomus sp2 and Glomus sp3) and one of the genus Acaulospora, which was identified at species level (Acaulospora mellea). Greater soil diversity was verified with pH 5.9 and phosphorus concentration of 111 mg dm-3, occurring two species of genus Glomus and A. mellea. Based on literature data, this may be the first record of this species of Acaulospora mellea in Antarctic soils, colonizing D. antarctica plants.

Air-sea interaction regimes in the sub-Antarctic Southern Ocean and Antarctic marginal ice zone revealed by icebreaker measurements

Science.gov (United States)

Yu, Lisan; Jin, Xiangze; Schulz, Eric W.; Josey, Simon A.

2017-08-01

This study analyzed shipboard air-sea measurements acquired by the icebreaker Aurora Australis during its off-winter operation in December 2010 to May 2012. Mean conditions over 7 months (October-April) were compiled from a total of 22 ship tracks. The icebreaker traversed the water between Hobart, Tasmania, and the Antarctic continent, providing valuable in situ insight into two dynamically important, yet poorly sampled, regimes: the sub-Antarctic Southern Ocean and the Antarctic marginal ice zone (MIZ) in the Indian Ocean sector. The transition from the open water to the ice-covered surface creates sharp changes in albedo, surface roughness, and air temperature, leading to consequential effects on air-sea variables and fluxes. Major effort was made to estimate the air-sea fluxes in the MIZ using the bulk flux algorithms that are tuned specifically for the sea-ice effects, while computing the fluxes over the sub-Antarctic section using the COARE3.0 algorithm. The study evidenced strong sea-ice modulations on winds, with the southerly airflow showing deceleration (convergence) in the MIZ and acceleration (divergence) when moving away from the MIZ. Marked seasonal variations in heat exchanges between the atmosphere and the ice margin were noted. The monotonic increase in turbulent latent and sensible heat fluxes after summer turned the MIZ quickly into a heat loss regime, while at the same time the sub-Antarctic surface water continued to receive heat from the atmosphere. The drastic increase in turbulent heat loss in the MIZ contrasted sharply to the nonsignificant and seasonally invariant turbulent heat loss over the sub-Antarctic open water.Plain Language SummaryThe icebreaker Aurora Australis is a research and supply vessel that is regularly chartered by the Australian Antarctic Division during the southern summer to operate in waters between Hobart, Tasmania, and Antarctica. The vessel serves as the main lifeline to three permanent research stations on the

Balance of the West Antarctic Ice Sheet

Science.gov (United States)

2002-01-01

For several decades, measurements of the West Antarctic Ice Sheet showed it to be retreating rapidly. But new data derived from satellite-borne radar sensors show the ice sheet to be growing. Changing Antarctic ice sheets remains an area of high scientific interest, particularly in light of recent global warming concerns. These new findings are significant because scientists estimate that sea level would rise 5-6 meters (16-20 feet) if the ice sheet collapsed into the sea. Do these new measurements signal the end of the ice sheet's 10,000-year retreat? Or, are these new satellite data simply much more accurate than the sparse ice core and surface measurements that produced the previous estimates? Another possibility is that the ice accumulation may simply indicate that the ice sheet naturally expands and retreats in regular cycles. Cryologists will grapple with these questions, and many others, as they examine the new data. The image above depicts the region of West Antarctica where scientists measured ice speed. The fast-moving central ice streams are shown in red. Slower tributaries feeding the ice streams are shown in blue. Green areas depict slow-moving, stable areas. Thick black lines depict the areas that collect snowfall to feed their respective ice streams. Reference: Ian Joughin and Slawek Tulaczyk Science Jan 18 2002: 476-480. Image courtesy RADARSAT Antarctic Mapping Project

Ocean acidification changes the structure of an Antarctic coastal protistan community

Science.gov (United States)

Hancock, Alyce M.; Davidson, Andrew T.; McKinlay, John; McMinn, Andrew; Schulz, Kai G.; van den Enden, Rick L.

2018-04-01

Antarctic near-shore waters are amongst the most sensitive in the world to ocean acidification. Microbes occupying these waters are critical drivers of ecosystem productivity, elemental cycling and ocean biogeochemistry, yet little is known about their sensitivity to ocean acidification. A six-level, dose-response experiment was conducted using 650 L incubation tanks (minicosms) adjusted to a gradient in fugacity of carbon dioxide (fCO2) from 343 to 1641 µatm. The six minicosms were filled with near-shore water from Prydz Bay, East Antarctica, and the protistan composition and abundance was determined by microscopy during 18 days of incubation. No CO2-related change in the protistan community composition was observed during the initial 8 day acclimation period under low light. Thereafter, the response of both autotrophic and heterotrophic protists to fCO2 was species-specific. The response of diatoms was mainly cell size related; microplanktonic diatoms ( > 20 µm) increased in abundance with low to moderate fCO2 (343-634 µatm) but decreased at fCO2 ≥ 953 µatm. Similarly, the abundance of Phaeocystis antarctica increased with increasing fCO2 peaking at 634 µatm. Above this threshold the abundance of micro-sized diatoms and P. antarctica fell dramatically, and nanoplanktonic diatoms ( ≤ 20 µm) dominated, therefore culminating in a significant change in the protistan community composition. Comparisons of these results with previous experiments conducted at this site show that the fCO2 thresholds are similar, despite seasonal and interannual differences in the physical and biotic environment. This suggests that near-shore microbial communities are likely to change significantly near the end of this century if anthropogenic CO2 release continues unabated, with profound ramifications for near-shore Antarctic ecosystem food webs and biogeochemical cycling.

Remote sensing and skywave digital communication from antarctica.

Science.gov (United States)

Bergadà, Pau; Deumal, Marc; Vilella, Carles; Regué, Joan R; Altadill, David; Marsal, Santi

2009-01-01

This paper presents an overview of the research activities undertaken by La Salle and the Ebro Observatory in the field of remote sensing. On 2003 we started a research project with two main objectives: implement a long-haul oblique ionospheric sounder and transmit the data from remote sensors located at the Spanish Antarctic station Juan Carlos I to Spain. The paper focuses on a study of feasibility of two possible physical layer candidates for the skywave link between both points. A DS-SS based solution and an OFDM based solution are considered to achieve a reliable low-power low-rate communication system between Antarctica and Spain.

Constraining the Antarctic contribution to global sea-level change: ANDRILL and beyond

Science.gov (United States)

Naish, Timothy

2016-04-01

Observations, models and paleoclimate reconstructions suggest that Antarctica's marine-based ice sheets behave in an unstable manner with episodes of rapid retreat in response to warming climate. Understanding the processes involved in this "marine ice sheet instability" is key for improving estimates of Antarctic ice sheet contribution to future sea-level rise. Another motivating factor is that far-field sea-level reconstructions and ice sheet models imply global mean sea level (GMSL) was up to 20m and 10m higher, respectively, compared with present day, during the interglacials of the warm Pliocene (~4-3Ma) and Late Pleistocene (at ~400ka and 125ka). This was when atmospheric CO2 was between 280 and 400ppm and global average surface temperatures were 1 to 3°C warmer, suggesting polar ice sheets are highly sensitive to relatively modest increases in climate forcing. Such magnitudes of GMSL rise not only require near complete melt of the Greenland Ice Sheet and the West Antarctic Ice Sheet, but a substantial retreat of marine-based sectors of East Antarctic Ice Sheet. Recent geological drilling initiatives on the continental margin of Antarctica from both ship- (e.g. IODP; International Ocean Discovery Program) and ice-based (e.g. ANDRILL/Antarctic Geological Drilling) platforms have provided evidence supporting retreat of marine-based ice. However, without direct access through the ice sheet to archives preserved within sub-glacial sedimentary basins, the volume and extent of ice sheet retreat during past interglacials cannot be directly constrained. Sediment cores have been successfully recovered from beneath ice shelves by the ANDRILL Program and ice streams by the WISSARD (Whillans Ice Stream Sub-glacial Access Research Drilling) Project. Together with the potential of the new RAID (Rapid Access Ice Drill) initiative, these demonstrate the technological feasibility of accessing the subglacial bed and deeper sedimentary archives. In this talk I will outline the

Re-searching the land of penguins: Antarctica

International Nuclear Information System (INIS)

Pal, Rupali; Dhabekar, Bhushan

2017-01-01

This article is a narrative describing the activities and valuable experiences of the authors during their 35 Antarctic Expedition. The interest and dedication of Indian scientists who participate in these expeditions every year for the quest of science and excellence is undeterred by the extreme living conditions and hardships faced on the icy continent. In this expedition, the authors conducted extensive surveys for radiation mapping in and around the 'Bharati' station, Antarctica and have collected several samples of water, soil and rock for analysis. These are being probed for their radioactivity content using various analytical techniques. A scientific report based on the outcomes and observations will be published in the near future. (author)

Antarctica and the strategic plan for biodiversity

Science.gov (United States)

Chown, Steven L.; Brooks, Cassandra M.; Terauds, Aleks; Le Bohec, Céline; van Klaveren-Impagliazzo, Céline; Whittington, Jason D.; Butchart, Stuart H. M.; Coetzee, Bernard W. T.; Collen, Ben; Convey, Peter; Gaston, Kevin J.; Gilbert, Neil; Gill, Mike; Höft, Robert; Johnston, Sam; Kennicutt, Mahlon C.; Kriesell, Hannah J.; Le Maho, Yvon; Lynch, Heather J.; Palomares, Maria; Puig-Marcó, Roser; Stoett, Peter; McGeoch, Melodie A.

2017-01-01

The Strategic Plan for Biodiversity, adopted under the auspices of the Convention on Biological Diversity, provides the basis for taking effective action to curb biodiversity loss across the planet by 2020—an urgent imperative. Yet, Antarctica and the Southern Ocean, which encompass 10% of the planet’s surface, are excluded from assessments of progress against the Strategic Plan. The situation is a lost opportunity for biodiversity conservation globally. We provide such an assessment. Our evidence suggests, surprisingly, that for a region so remote and apparently pristine as the Antarctic, the biodiversity outlook is similar to that for the rest of the planet. Promisingly, however, much scope for remedial action exists. PMID:28350825

Antarctica and the strategic plan for biodiversity.

Directory of Open Access Journals (Sweden)

Steven L Chown

2017-03-01

Full Text Available The Strategic Plan for Biodiversity, adopted under the auspices of the Convention on Biological Diversity, provides the basis for taking effective action to curb biodiversity loss across the planet by 2020-an urgent imperative. Yet, Antarctica and the Southern Ocean, which encompass 10% of the planet's surface, are excluded from assessments of progress against the Strategic Plan. The situation is a lost opportunity for biodiversity conservation globally. We provide such an assessment. Our evidence suggests, surprisingly, that for a region so remote and apparently pristine as the Antarctic, the biodiversity outlook is similar to that for the rest of the planet. Promisingly, however, much scope for remedial action exists.

Italian research on Antarctic atmosphere: 1st workshop. Ricerche italiane sull'atmosfera antartica: 1o workshop

Energy Technology Data Exchange (ETDEWEB)

Colacino, M. (ed.); Giovannelli, G. (ed.); Stefanutti, L. (ed.)

1989-01-01

The papers and reports, presented at this 1st workshop on 'Italian research on antarctic atmosphere', deal with several main topics: meteorology and climatology, aerosol and tropospheric clouds, planetary boundary layer, chemical-physic stratospheric property, aeronomy. They define the stage of development of Italian research in this area after 3 years of activity in Antarctica.

Personality Testing in Antarctic Expeditioners: Cross Cultural Comparisons and Evidence for Generalizability

Science.gov (United States)

Musson, D. M.; Sandal, G. M.; Harper, M. L.; Helmreich, R. L.

Antarctica provides an ideal environment in which to study human behaviour under conditions of isolation and confinement. Such research is currently being conducted through several national Antarctic research programs, with the subject pool for these investigations necessarily consisting of individuals from multiple nationalities. Cross-cultural research has shown, however, that psychological traits and individual values may vary significantly between national and ethnic groups. Until now, there has been an implicit assumption that Antarctic personnel are essentially similar from one national program to another and that therefore findings from any one nation's Antarctic program should generalize to another, as well as to other domains such as spaceflight. We believe that it is necessary to validate this assumption through empirical research. This objective of this analysis was to determine the degree of similarity between the psychological testing profiles of Antarctic research personnel from different national Antarctic programs, and to determine the degrees of similarity or difference of these personnel to a normative population. METHODS In separate studies, Antarctic personnel from Australia (n=57), Norway (=37), and Great Britain (n=145) were administered the Personal Characteristics Inventory (PCI) before departing to Antarctica. The PCI is a battery consisting of 11 psychological scales designed to assess specific traits related to achievement and interpersonal competence that have been shown to be particularly salient to human performance under stressful and complex conditions. For comparative normative data, a group of 441 U.S. undergraduate students were also administered the PCI. Due to historical reasons, researchers in this study used 2 versions of the PCI, and only 9 of the 11 scales were directly equivalent. RESULTS For the three national Antarctic groups (Australia, Norway, and Great Britain), no significant variation was found between group mean

A meta-analysis of human disturbance impacts on Antarctic wildlife.

Science.gov (United States)

Coetzee, Bernard W T; Chown, Steven L

2016-08-01

Evidence-based assessments are increasingly recognized as the best-practice approach to determine appropriate conservation interventions, but such assessments of the impact of human disturbance on wildlife are rare. Human disturbance comprises anthropogenic activities that are typically non-lethal, but may cause short- and/or longer-term stress and fitness responses in wildlife. Expanding human activity in the Antarctic region is of particular concern because it increases the scope and potential for increased human disturbance to wildlife in a region that is often thought of as relatively untouched by anthropogenic influences. Here, we use a meta-analytical approach to synthesise research on human disturbance to wildlife over the last three decades in the Antarctic and sub-Antarctic region. We combine data from 62 studies across 21 species on the behavioural, physiological and population responses of wildlife to pedestrian, vehicle and research disturbances. The overall effect size indicated a small, albeit statistically significant negative effect of disturbance (-0.39; 95% CI: -0.60 to -0.18). Negative effects were found for both physiological and population responses, but no evidence was found for a significant impact on wildlife behavioural responses. Negative effects were found across pedestrian, vehicle and research disturbances. Significant and high among-study heterogeneity was found in both disturbance and response sub-groups. Among species, it remains unclear to what extent different forms of disturbance translate into negative population responses. Most current guidelines to limit wildlife disturbance impacts in Antarctica recommend that approaches be tailored to animal behavioural cues, but our work demonstrates that behavioural changes do not necessarily reflect more cryptic, and more deleterious impacts, such as changes in physiology. In consequence, we recommend that pedestrian approach guidelines in the Antarctic region be revisited. Due to the high

Modeling the Thermal Interactions of Meteorites Below the Antarctic Ice

Science.gov (United States)

Oldroyd, William Jared; Radebaugh, Jani; Stephens, Denise C.; Lorenz, Ralph; Harvey, Ralph; Karner, James

2017-10-01

Meteorites with high specific gravities, such as irons, appear to be underrepresented in Antarctic collections over the last 40 years. This underrepresentation is in comparison with observed meteorite falls, which are believed to represent the actual population of meteorites striking Earth. Meteorites on the Antarctic ice sheet absorb solar flux, possibly leading to downward tunneling into the ice, though observations of this in action are very limited. This descent is counteracted by ice sheet flow supporting the meteorites coupled with ablation near mountain margins, which helps to force meteorites towards the surface. Meteorites that both absorb adequate thermal energy and are sufficiently dense may instead reach a shallow equilibrium depth as downward melting overcomes upward forces during the Antarctic summer. Using a pyronometer, we have measured the incoming solar flux at multiple depths in two deep field sites in Antarctica, the Miller Range and Elephant Moraine. We compare these data with laboratory analogues and model the thermal and physical interactions between a variety of meteorites and their surroundings. Our Matlab code model will account for a wide range of parameters used to characterize meteorites in an Antarctic environment. We will present the results of our model along with depth estimates for several types of meteorites. The recovery of an additional population of heavy meteorites would increase our knowledge of the formation and composition of the solar system.

The sources and composition of humus in some soils of West Antarctica

Science.gov (United States)

Abakumov, E. V.

2010-05-01

Original data on humus-forming substances and their elemental and biochemical compositions in Antarctic soils are discussed. Mosses, lichens, algae, remains of higher vascular plants, and penguin guano of two types differ considerably in their chemical compositions. This leads to significant differences in the formation of humic substances in plant materials themselves in the course of their transformation. However, no significant differences in the composition of humus in the fine earth of soils developing under different humus-forming materials have been revealed, which may be related to the extremely low rates of humification. Significant differences between the soils of Antarctic landscapes proper and the soils of the Subantarctic King George Island are only observed in the humus enrichment with nitrogen. The soils of Antarctica are low-humus soils with the humate-fulvate or fulvate types of humus.

Aerobiology over Antarctica – a new initiative for atmospheric ecology

Directory of Open Access Journals (Sweden)

David Anthony Pearce

2016-02-01

Full Text Available The role of aerial dispersal in shaping patterns of biodiversity remains poorly understood, mainly due to a lack of coordinated efforts in gathering data at appropriate temporal and spatial scales. It has been long known that the rate of dispersal to an ecosystem can significantly influence ecosystem dynamics, and that aerial transport has been identified as an important source of biological input to remote locations. With the considerable effort devoted in recent decades to understanding atmospheric circulation in the south polar region, a unique opportunity has emerged to investigate the atmospheric ecology of Antarctica, from local to continental scales. This concept note identifies key questions in Antarctic microbial biogeography and the need for standardized sampling and analysis protocols to address such questions. A consortium of polar aerobiologists is established to bring together researchers with a common interest in the airborne dispersion of microbes and other propagules in the Antarctic, with opportunities for comparative studies in the Arctic.

LEP Events, TLE's, and Q-bursts observed from the Antarctic

Science.gov (United States)

Moore, R. C.; Kim, D.; Flint, Q. A.

2017-12-01

ELF/VLF measurements at Palmer Station, McMurdo Station, and South Pole Station, Antarctica are used to detect lightning-generated ELF/VLF radio atmospherics from around the globe and to remote sense ionospheric disturbances in the Southern hemisphere. The Antarctic ELF/VLF receivers complement a Northern hemisphere ELF/VLF monitoring array. In this paper, we present our latest observational results, including a full statistical analysis of conjugate observations of lightning-induced electron precipitation and radio atmospherics associated specifically with the transient luminous events known as gigantic jets and sprites.

Natural products mediating ecological interactions in Antarctic benthic communities: a mini-review of the known molecules.

Science.gov (United States)

Núñez-Pons, L; Avila, C

2015-07-01

Out of the many bioactive compounds described from the oceans, only a small fraction have been studied for their ecological significance. Similarly, most chemically mediated interactions are not well understood, because the molecules involved remain unrevealed. In Antarctica, this gap in knowledge is even more acute in comparison to tropical or temperate regions, even though polar organisms are also prolific producers of chemical defenses, and pharmacologically relevant products are being reported from the Southern Ocean. The extreme and unique marine environments surrounding Antarctica along with the numerous unusual interactions taking place in benthic communities are expected to select for novel functional secondary metabolites. There is an urgent need to comprehend the evolutionary role of marine derived substances in general, and particularly at the Poles, since molecules of keystone significance are vital in species survival, and therefore, in structuring the communities. Here we provide a mini-review on the identified marine natural products proven to have an ecological function in Antarctic ecosystems. This report recapitulates some of the bibliography from original Antarctic reviews, and updates the new literature in the field from 2009 to the present.

Glacial isostatic stress shadowing by the Antarctic ice sheet

Science.gov (United States)

Ivins, E. R.; James, T. S.; Klemann, V.

2005-01-01

Numerous examples of fault slip that offset late Quaternary glacial deposits and bedrock polish support the idea that the glacial loading cycle causes earthquakes in the upper crust. A semianalytical scheme is presented for quantifying glacial and postglacial lithospheric fault reactivation using contemporary rock fracture prediction methods. It extends previous studies by considering differential Mogi-von Mises stresses, in addition to those resulting from a Coulomb analysis. The approach utilizes gravitational viscoelastodynamic theory and explores the relationships between ice mass history and regional seismicity and faulting in a segment of East Antarctica containing the great Antarctic Plate (Balleny Island) earthquake of 25 March 1998 (Mw 8.1). Predictions of the failure stress fields within the seismogenic crust are generated for differing assumptions about background stress orientation, mantle viscosity, lithospheric thickness, and possible late Holocene deglaciation for the D91 Antarctic ice sheet history. Similar stress fracture fields are predicted by Mogi-von Mises and Coulomb theory, thus validating previous rebound Coulomb analysis. A thick lithosphere, of the order of 150-240 km, augments stress shadowing by a late melting (middle-late Holocene) coastal East Antarctic ice complex and could cause present-day earthquakes many hundreds of kilometers seaward of the former Last Glacial Maximum grounding line.

Abundance and breeding distribution of seabirds in the northern part of the Danco Coast, Antarctic Peninsula

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Mariana A. Juáres

2013-02-01

Full Text Available Seabird abundances and breeding distribution have the potential to serve as ecological indicators. The western Antarctic Peninsula is one of the three sites in the world with the greatest increases in local temperature during the last 50 years. The aim of this study was to monitor the distribution and abundance of breeding populations of seabirds in the northern sector of the Danco Coast, north-west of the Antarctic Peninsula, during the breeding season 2010/11. The birds were the Wilson′s storm petrel (Oceanites oceanicus, South Polar skua (Stercorarius maccormicki, kelp gull (Larus dominicanus, Antarctic tern (Sterna vittata, snowy sheathbill (Chionis alba, chinstrap penguin (Pygoscelis antarctica, southern giant petrel (Macronectes giganteus, gentoo penguin (Pygoscelis papua, Cape petrel (Daption capense and Antarctic shag (Phalacrocorax bransfieldensis. Annual breeding population growth increased in pygoscelids, southern giant petrel and sheathbill, and for the remaining species, breeding population trends were stable. Given that seabird populations can provide valuable information on the conditions of their feeding and nesting environments, this study highlights the need to maintain basics monitoring studies.

Effects of iron limitation on photosynthesis and carbohydrate metabolism in the Antarctic diatom Chaetoceros brevis (Bacillariophyceae)

NARCIS (Netherlands)

van Oijen, T; van Leeuwe, MA; Gieskes, WWC; de Baar, HJW

Iron, one of the structural elements of organic components that play an essential role in photosynthesis and nitrogen assimilation of plants, is available at extremely low concentrations in large parts of the Southern Ocean's surface waters. We tested the hypothesis that photosynthesis is the

Reproductive output of mosses under experimental warming on Fildes Peninsula, King George Island, maritime Antarctica

OpenAIRE

Casanova-Katny, A.; Torres-Mellado, G. A.; Eppley, S. M.

2016-01-01

BACKGROUND: Mosses dominate much of the vegetation in the Antarctic, but the effect of climatic change on moss growth and sexual reproduction has scarcely been studied. In Antarctica, mosses infrequently produce sporophytes; whether this is due to physiological limitation or an adaptive response is unknown. We studied the effect of experimental warming (with Open Top Chambers, OTCs) on sporophyte production on Fildes Peninsula, King George Island for four moss species (Bartramia patens, Henne...

An emission inventory of sulfur from anthropogenic sources in Antarctica

Directory of Open Access Journals (Sweden)

S. V. Shirsat

2009-05-01

Full Text Available This paper presents first results of a comprehensive emission inventory of chemical species from anthropogenic activities (power generation, vehicles, ships and aircraft in Antarctica, covering the 2004–2005 period.

The inventory is based on estimated emission rates of fuel consumption provided by some of the Antarctic research stations. Since the emission sources have different modes of operation and use a variety of fuel, the emission flux rate of chemical species is calculated by multiplying the fuel consumption value with the density of fuel and appropriate emission factors. A separate inventory is prepared for each anthropogenic emission source in Antarctica.

Depending on the type of operation, emission rates of SO₂, and BC (Black Carbon, from shipping only have been calculated using the above technique. However, only results of SO₂ emissions from each source are presented here. Emission inventory maps of SO₂ depicting the track/path taken by each mobile source are shown. The total annual SO₂ is 158 Mg from power generation and vehicle operations, 3873 Mg from ships and 56 Mg from aircraft for 2004–2005 and these values undergo strong seasonality following the human activity in Antarctica. Though these figures are small when compared to the emissions at most other regions of the world, they are an indication that human presence in Antarctica leads to at least local pollution. The sources are mainly line and point sources and thus the local pollution potentially is relatively strong.

Direct gravimetric determination of aerosol mass concentration in central antarctica.

Science.gov (United States)

Annibaldi, Anna; Truzzi, Cristina; Illuminati, Silvia; Scarponi, Giuseppe

2011-01-01

In Antarctica, experimental difficulties due to extreme conditions have meant that aerosol mass has rarely been measured directly by gravimetry, and only in coastal areas where concentrations were in the range of 1-7 μg m(-3). The present work reports on a careful differential weighing methodology carried out for the first time on the plateau of central Antarctica (Dome C, East Antarctica). To solve problems of accurate aerosol mass measurements, a climatic room was used for conditioning and weighing filters. Measurements were carried out in long stages of several hours of readings with automatic recording of temperature/humidity and mass. This experimental scheme allowed us to sample from all the measurements (up to 2000) carried out before and after exposure, those which were recorded under the most stable humidity conditions and, even more importantly, as close to each other as possible. The automatic reading of the mass allowed us in any case to obtain hundreds of measurements from which to calculate average values with uncertainties sufficiently low to meet the requirements of the differential weighing procedure (±0.2 mg in filter weighing, between ±7% and ±16% both in aerosol mass and concentration measurements). The results show that the average summer aerosol mass concentration (aerodynamic size ≤10 μm) in central Antarctica is about 0.1 μg m(-3), i.e., about 1/10 of that of coastal Antarctic areas. The concentration increases by about 4-5 times at a site very close to the station.

Unexpectedly high ultrafine aerosol concentrations above East Antarctic sea ice

Directory of Open Access Journals (Sweden)

R. S. Humphries

2016-02-01

Full Text Available Better characterisation of aerosol processes in pristine, natural environments, such as Antarctica, have recently been shown to lead to the largest reduction in uncertainties in our understanding of radiative forcing. Our understanding of aerosols in the Antarctic region is currently based on measurements that are often limited to boundary layer air masses at spatially sparse coastal and continental research stations, with only a handful of studies in the vast sea-ice region. In this paper, the first observational study of sub-micron aerosols in the East Antarctic sea ice region is presented. Measurements were conducted aboard the icebreaker Aurora Australis in spring 2012 and found that boundary layer condensation nuclei (CN3 concentrations exhibited a five-fold increase moving across the polar front, with mean polar cell concentrations of 1130 cm−3 – higher than any observed elsewhere in the Antarctic and Southern Ocean region. The absence of evidence for aerosol growth suggested that nucleation was unlikely to be local. Air parcel trajectories indicated significant influence from the free troposphere above the Antarctic continent, implicating this as the likely nucleation region for surface aerosol, a similar conclusion to previous Antarctic aerosol studies. The highest aerosol concentrations were found to correlate with low-pressure systems, suggesting that the passage of cyclones provided an accelerated pathway, delivering air masses quickly from the free troposphere to the surface. After descent from the Antarctic free troposphere, trajectories suggest that sea-ice boundary layer air masses travelled equatorward into the low-albedo Southern Ocean region, transporting with them emissions and these aerosol nuclei which, after growth, may potentially impact on the region's radiative balance. The high aerosol concentrations and their transport pathways described here, could help reduce the discrepancy currently present between

Unexpectedly high ultrafine aerosol concentrations above East Antarctic sea ice

Science.gov (United States)

Humphries, R. S.; Klekociuk, A. R.; Schofield, R.; Keywood, M.; Ward, J.; Wilson, S. R.

2016-02-01

Better characterisation of aerosol processes in pristine, natural environments, such as Antarctica, have recently been shown to lead to the largest reduction in uncertainties in our understanding of radiative forcing. Our understanding of aerosols in the Antarctic region is currently based on measurements that are often limited to boundary layer air masses at spatially sparse coastal and continental research stations, with only a handful of studies in the vast sea-ice region. In this paper, the first observational study of sub-micron aerosols in the East Antarctic sea ice region is presented. Measurements were conducted aboard the icebreaker Aurora Australis in spring 2012 and found that boundary layer condensation nuclei (CN3) concentrations exhibited a five-fold increase moving across the polar front, with mean polar cell concentrations of 1130 cm-3 - higher than any observed elsewhere in the Antarctic and Southern Ocean region. The absence of evidence for aerosol growth suggested that nucleation was unlikely to be local. Air parcel trajectories indicated significant influence from the free troposphere above the Antarctic continent, implicating this as the likely nucleation region for surface aerosol, a similar conclusion to previous Antarctic aerosol studies. The highest aerosol concentrations were found to correlate with low-pressure systems, suggesting that the passage of cyclones provided an accelerated pathway, delivering air masses quickly from the free troposphere to the surface. After descent from the Antarctic free troposphere, trajectories suggest that sea-ice boundary layer air masses travelled equatorward into the low-albedo Southern Ocean region, transporting with them emissions and these aerosol nuclei which, after growth, may potentially impact on the region's radiative balance. The high aerosol concentrations and their transport pathways described here, could help reduce the discrepancy currently present between simulations and observations of

Biogeographical note on Antarctic microflorae: Endemism and cosmopolitanism

Directory of Open Access Journals (Sweden)

Waqar Azeem Jadoon

2013-11-01

Full Text Available This study deals with the biogeography of Antarctic microflora (Antarctica acts as best model to study microbial biogeography such as cyanobacteria and selected halophiles with special emphasis on Halomonas variabilis and Bacillus licheniformis. Halophiles are known to be resistant not only to salt stress, but also to extreme temperature, pressure, and aridity and they are capable of surviving in harsh environments such as polar regions, deep-sea habitats, and deserts. Many microbes are known to be resistant to hostile environmental conditions, and are capable of surviving in harsh environments. Our group has isolated 444 strains belonging to 28 genera of halophiles from various environments around the world. The 16S rRNA gene sequences revealed that many of the isolated strains from geographically distant habitats having different environmental conditions, were closely related to each other, with some strains possessing 100% identical sequences. Organisms possessing survival mechanism such as spore formation are usually ubiquitous. The genus Halomonas is represented by potentially endemic strains and the ubiquitous H. variabilis, while spore-forming B. licheniformis showed cosmopolitan distribution. One potentially endemic (moderate endemicity that is regional and/or continental distribution strain was reported from Syowa station, East Antarctica, and Mario Zucchelli station, West Antarctica, which are geographically separated by 3000 km. Moreover, 15 strains having 100% similarity with B. licheniformis were considered cosmopolitans. The results of this work provide support for the middle-ground model that some microbes have moderate endemicity and others have cosmopolitan distribution. These results will contribute to a greater understanding of microbial biogeography with special emphasis on Antarctica.

Geothermal Heat Flux and Upper Mantle Viscosity across West Antarctica: Insights from the UKANET and POLENET Seismic Networks

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O'Donnell, J. P.; Dunham, C.; Stuart, G. W.; Brisbourne, A.; Nield, G. A.; Whitehouse, P. L.; Hooper, A. J.; Nyblade, A.; Wiens, D.; Aster, R. C.; Anandakrishnan, S.; Huerta, A. D.; Wilson, T. J.; Winberry, J. P.

2017-12-01

Quantifying the geothermal heat flux at the base of ice sheets is necessary to understand their dynamics and evolution. The heat flux is a composite function of concentration of upper crustal radiogenic elements and flow of heat from the mantle into the crust. Radiogenic element concentration varies with tectonothermal age, while heat flow across the crust-mantle boundary depends on crustal and lithospheric thicknesses. Meanwhile, accurately monitoring current ice mass loss via satellite gravimetry or altimetry hinges on knowing the upper mantle viscosity structure needed to account for the superimposed glacial isostatic adjustment (GIA) signal in the satellite data. In early 2016 the UK Antarctic Network (UKANET) of 10 broadband seismometers was deployed for two years across the southern Antarctic Peninsula and Ellsworth Land. Using UKANET data in conjunction with seismic records from our partner US Polar Earth Observing Network (POLENET) and the Antarctic Seismographic Argentinian Italian Network (ASAIN), we have developed a 3D shear wave velocity model of the West Antarctic crust and uppermost mantle based on Rayleigh and Love wave phase velocity dispersion curves extracted from ambient noise cross-correlograms. We combine seismic receiver functions with the shear wave model to help constrain the depth to the crust-mantle boundary across West Antarctica and delineate tectonic domains. The shear wave model is subsequently converted to temperature using a database of densities and elastic properties of minerals common in crustal and mantle rocks, while the various tectonic domains are assigned upper crustal radiogenic element concentrations based on their inferred tectonothermal ages. We combine this information to map the basal geothermal heat flux variation across West Antarctica. Mantle viscosity depends on factors including temperature, grain size, the hydrogen content of olivine and the presence of melt. Using published mantle xenolith and magnetotelluric

Age-related environmental gradients influence invertebrate distribution in the Prince Charles Mountains, East Antarctica.

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Czechowski, Paul; White, Duanne; Clarke, Laurence; McKay, Alan; Cooper, Alan; Stevens, Mark I

2016-12-01

The potential impact of environmental change on terrestrial Antarctic ecosystems can be explored by inspecting biodiversity patterns across large-scale gradients. Unfortunately, morphology-based surveys of Antarctic invertebrates are time-consuming and limited by the cryptic nature of many taxa. We used biodiversity information derived from high-throughput sequencing (HTS) to elucidate the relationship between soil properties and invertebrate biodiversity in the Prince Charles Mountains, East Antarctica. Across 136 analysed soil samples collected from Mount Menzies, Mawson Escarpment and Lake Terrasovoje, we found invertebrate distribution in the Prince Charles Mountains significantly influenced by soil salinity and/or sulfur content. Phyla Tardigrada and Arachnida occurred predominantly in low-salinity substrates with abundant nutrients, whereas Bdelloidea (Rotifera) and Chromadorea (Nematoda) were more common in highly saline substrates. A significant correlation between invertebrate occurrence, soil salinity and time since deglaciation indicates that terrain age indirectly influences Antarctic terrestrial biodiversity, with more recently deglaciated areas supporting greater diversity. Our study demonstrates the value of HTS metabarcoding to investigate environmental constraints on inconspicuous soil biodiversity across large spatial scales.

Fuel oil and dispersant toxicity to the Antarctic sea urchin (Sterechinus neumayeri).

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Alexander, Frances J; King, Catherine K; Reichelt-Brushett, Amanda J; Harrison, Peter L

2017-06-01

The risk of a major marine fuel spill in Antarctic waters is increasing, yet there are currently no standard or suitable response methods under extreme Antarctic conditions. Fuel dispersants may present a possible solution; however, little data exist on the toxicity of dispersants or fuels to Antarctic species, thereby preventing informed management decisions. Larval development toxicity tests using 3 life history stages of the Antarctic sea urchin (Sterechinus neumayeri) were completed to assess the toxicity of physically dispersed, chemically dispersed, and dispersant-only water-accommodated fractions (WAFs) of an intermediate fuel oil (IFO 180, BP) and the chemical dispersant Slickgone NS (Dasic International). Despite much lower total petroleum hydrocarbon concentrations, physically dispersed fuels contained higher proportions of low-to-intermediate weight carbon compounds and were generally at least an order of magnitude more toxic than chemically dispersed fuels. Based on concentrations that caused 50% abnormality (EC50) values, the embryonic unhatched blastula life stage was the least affected by fuels and dispersants, whereas the larval 4-armed pluteus stage was the most sensitive. The present study is the first to investigate the possible implications of the use of fuel dispersants for fuel spill response in Antarctica. The results indicate that the use of a fuel dispersant did not increase the hydrocarbon toxicity of IFO 180 to the early life stages of Antarctic sea urchins, relative to physical dispersal. Environ Toxicol Chem 2017;36:1563-1571. © 2016 SETAC. © 2016 SETAC.

My IGY in Antarctica

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Bentley, Charles

2012-01-01

Dr Charles Bentley is the A.P. Crary Professor Emeritus of Geophysics, Department of Geology and Geophysics, University of Wisconsin-Madison. Dr. Bentley joined the Arctic Institute of North America in 1956 to participate in International Geophysical Year (IGY)-related activities in the Antarctic. He wintered over consecutively in 1957 and 1958 at Byrd Station, a station in the interior of West Antarctica that housed 24 men each winter - 12 Navy support people and 12 civilian scientists/technicians. During the austral summers, he also participated in over-snow traverses, first as co-leader, then leader (the other coleader went home after the first year). These traverses consisted of six men and three vehicles, and lasted several months. These traverses covered more than 1609 kilometers (1000 miles) of largely unmapped and unphotographed terrain. During these traverses, connections to Byrd Station were by radio (daily, when the transmission conditions were good enough) and roughly every 2 weeks by resupply flight.

Temporal and spatial variabilities of Antarctic ice mass changes inferred by GRACE in a Bayesian framework

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Wang, L.; Davis, J. L.; Tamisiea, M. E.

2017-12-01

The Antarctic ice sheet (AIS) holds about 60% of all fresh water on the Earth, an amount equivalent to about 58 m of sea-level rise. Observation of AIS mass change is thus essential in determining and predicting its contribution to sea level. While the ice mass loss estimates for West Antarctica (WA) and the Antarctic Peninsula (AP) are in good agreement, what the mass balance over East Antarctica (EA) is, and whether or not it compensates for the mass loss is under debate. Besides the different error sources and sensitivities of different measurement types, complex spatial and temporal variabilities would be another factor complicating the accurate estimation of the AIS mass balance. Therefore, a model that allows for variabilities in both melting rate and seasonal signals would seem appropriate in the estimation of present-day AIS melting. We present a stochastic filter technique, which enables the Bayesian separation of the systematic stripe noise and mass signal in decade-length GRACE monthly gravity series, and allows the estimation of time-variable seasonal and inter-annual components in the signals. One of the primary advantages of this Bayesian method is that it yields statistically rigorous uncertainty estimates reflecting the inherent spatial resolution of the data. By applying the stochastic filter to the decade-long GRACE observations, we present the temporal variabilities of the AIS mass balance at basin scale, particularly over East Antarctica, and decipher the EA mass variations in the past decade, and their role in affecting overall AIS mass balance and sea level.

Brucella antibody seroprevalence in Antarctic seals (Arctocephalus gazella, Leptonychotes weddellii and Mirounga leonina).

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Jensen, Silje-Kristin; Nymo, Ingebjørg Helena; Forcada, Jaume; Hall, Ailsa; Godfroid, Jacques

2013-09-03

Brucellosis is a worldwide infectious zoonotic disease caused by Gram-negative bacteria of the genus Brucella, and Brucella infections in marine mammals were first reported in 1994. A serosurvey investigating the presence of anti-Brucella antibodies in 3 Antarctic pinniped species was undertaken with a protein A/G indirect enzyme-linked immunosorbent assay (iELISA) and the Rose Bengal test (RBT). Serum samples from 33 Weddell seals Leptonychotes weddelli were analysed, and antibodies were detected in 8 individuals (24.2%) with the iELISA and in 21 (65.6%) with the RBT. We tested 48 southern elephant seal Mirounga leonina sera and detected antibodies in 2 animals (4.7%) with both the iELISA and the RBT. None of the 21 Antarctic fur seals Arctocephalus gazella was found positive. This is the first report of anti-Brucella antibodies in southern elephant seals. The potential impact of Brucella infection in pinnipeds in Antarctica is not known, but Brucella spp. are known to cause abortion in terrestrial species and cetaceans. Our findings suggest that Brucella infection in pinnipeds is present in the Antarctic, but to date B. pinnipedialis has not been isolated from any Antarctic pinniped species, leaving the confirmation of infection pending.

Technical procedures for aeromagnetic surveys in Antarctica during the Italian expeditions (1988-1992

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D. Damaske

1994-06-01

Full Text Available For most of Antarctica, the geophysical data now available are those of aeromagnetic surveys performed there from 1950 to 1960. Until 1984, the inaccurate positioning and insufficient monitoring of geomagnetic time variations allowed the investigation of the geomagnetic residual field only along profiles. The Ganovex IV aeromagnetic survey, performed by BGR-USGS over the Ross Sea and the Northern Victoria Land, and the geophysical investigations of BAS on the Southern Antarctic peninsula and the Ronne ice shelf region corresponds to the recent advancement of these techniques in Antarctica. The first experiments of aeromagnetic measurements, during the Italian expeditions in Antarctica were made during the 1988-1989 field season. Some geomagnetic helicopter borne profiles were accomplished with a Proton Precession Magnetometer (PPM in the Terra Nova Bay-Gerlache Inlet area. In the 1989-1990 ItaliAntartide expedition some profiles were flown over the suture between the Wilson and Bower terranes, in Northern Victoria Land. During the 1991-1992 expedition, in cooperation with researchers of BGR (Bundesanstalt fur Geowissenschaften und Rohstoffe of Hannover, the GITARA I (German ITalian Aeromagnetic Rescarch Antarctica program, as part of the LIRA (Litospheric Investigation in the Ross Sea Area project, was carried out. The investigated area lies between the latitudes 74°18' S and 75°18' S and the longitudes 160°30' E and 164°30'E and it corresponds to a portion of the North Victoria Land, located between the Eisenhower Range and the, DrygaIski Ice Tongue. The survey was made with a Cesium vapour magnetometer. The positioning system was of the “Range-Range” type, it consisted of three transmitters (beacons, installed inside the investigated area and located with GPS measurements. The line spacing was 4.4 km, with tie lines every 22 km. The survey covered an area of 6500 km2 . Four PPM base stations for the determination of the time variation

Global thermal niche models of two European grasses show high invasion risks in Antarctica.

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Pertierra, Luis R; Aragón, Pedro; Shaw, Justine D; Bergstrom, Dana M; Terauds, Aleks; Olalla-Tárraga, Miguel Ángel

2017-07-01

The two non-native grasses that have established long-term populations in Antarctica (Poa pratensis and Poa annua) were studied from a global multidimensional thermal niche perspective to address the biological invasion risk to Antarctica. These two species exhibit contrasting introduction histories and reproductive strategies and represent two referential case studies of biological invasion processes. We used a multistep process with a range of species distribution modelling techniques (ecological niche factor analysis, multidimensional envelopes, distance/entropy algorithms) together with a suite of thermoclimatic variables, to characterize the potential ranges of these species. Their native bioclimatic thermal envelopes in Eurasia, together with the different naturalized populations across continents, were compared next. The potential niche of P. pratensis was wider at the cold extremes; however, P. annua life history attributes enable it to be a more successful colonizer. We observe that particularly cold summers are a key aspect of the unique Antarctic environment. In consequence, ruderals such as P. annua can quickly expand under such harsh conditions, whereas the more stress-tolerant P. pratensis endures and persist through steady growth. Compiled data on human pressure at the Antarctic Peninsula allowed us to provide site-specific biosecurity risk indicators. We conclude that several areas across the region are vulnerable to invasions from these and other similar species. This can only be visualized in species distribution models (SDMs) when accounting for founder populations that reveal nonanalogous conditions. Results reinforce the need for strict management practices to minimize introductions. Furthermore, our novel set of temperature-based bioclimatic GIS layers for ice-free terrestrial Antarctica provide a mechanism for regional and global species distribution models to be built for other potentially invasive species. © 2017 John Wiley & Sons Ltd.

The occurrence and development of peat mounds on King George Island (Maritime Antarctic

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Jerzy Fabiszewski

2014-01-01

Full Text Available On King George Island, South Shetlands Islands, a type of peat formation has been discovered which has not previously been reported from the Antarctic. These formations are in shape of mounds up to 7x 15 m in area, with a peat layer of about I m thick. About twenty five cm below the surface there is a layer of permanently frozen peat. The mounds are covered by living mosses (Polytrichum alpinum and Drepanocladus uncinatus, Antarctic hair grass (Deschampsia antarctica and lichens. Erosion fissures occurring on the surface are evidence of contemporary drying and cessation of the mound's growth. The initial phase of the development of the mounds began with a community dominated by Calliergidium austro-stramineum and Deschampsia antarctica, and their further development has been due to peat accumulation formed almost entirely by Calliergidium. The location of the mounds is near a penguin rookery, which clearly conditioned the minerotrophic character of these formations, as compared with the "moss peat banks" formed by Chorisodontium aciphyllum and Polytrichum al-pestre. Moreover, the peat mounds differ from the latter in several ways, e.g. rate of growth and floristic composition. Radiocarbon dating of peat from the base of one mound gave an age of 4090±60 years B.P. This suggests that the age of the tundra on King George Island is about 5000-4000 years.

ADMAP-2: The second generation Antarctic crustal magnetic anomaly map.

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Ferraccioli, F.; Golynsky, A.; Golynsky, D.; Young, D. A.; Eagles, G.; Damaske, D.; Finn, C.; Aitken, A.; von Frese, R. R. B.; Ghidella, M. E.; Kim, H. R.; Hong, J.

2017-12-01

ADMAP-2 is the second generation crustal magnetic anomaly compilation for the Antarctic region south of 60°S. It was produced from more than 3.5 million line-km of near-surface terrestrial, airborne and marine magnetic observations collected since the International Geophysical Year 1957/58 through 2013. The data were edited, IGRF corrected, profile levelled and gridded at a 1.5-km interval on a polar stereographic projection using the minimum curvature technique. Given the ubiquitous polar cover of snow, ice and sea water, the magnetic anomaly compilation offers important constraints on the global tectonic processes and crustal properties of the Antarctic. It also links widely separated areas of outcrop to help unify disparate geologic studies, and provides insights on the lithospheric transition between Antarctica and adjacent oceans, as well as the geodynamic evolution of the Antarctic lithosphere in the assembly and break-up of the Gondwana, Rodinia, and Columbia supercontinents and key piercing points for reconstructing linkages between the protocontinents. The magnetic data together with ice-probing radar and gravity information greatly facilitate understanding the evolution of fundamental large-scale geological processes such as continental rifting, intraplate mountain building, subduction and terrane accretion processes, and intraplate basin formation.

Re-Evaluation of Geomagnetic Field Observation Data at Syowa Station, Antarctica

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K Takahashi

2013-05-01

Full Text Available The Japanese Antarctic Research Expedition has conducted geomagnetic observations at Syowa Station, Antarctica, since 1966. Geomagnetic variation data measured with a fluxgate magnetometer are not absolute but are relative to a baseline and show drift. To enhance the importance of the geomagnetic data at Syowa Station, therefore, it is necessary to correct the continuous variation data by using absolute baseline values acquired by a magnetic theodolite and proton magnetometer. However, the database of baseline values contains outliers. We detected outliers in the database and then converted the geomagnetic variation data to absolute values by using the reliable baseline values.

The use of Antarctic analogs for the Space Exploration Initiative

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Roberts, Barney; Lynch, John T.

1991-01-01

Potential approaches to the use of the Antarctic as an analog to the lunar and Mars planetary surface segments of the SEI are reviewed. It is concluded that a well-planned and sustained program of ground-based research and testing in environments analogous to the moon and Mars is a rational method for reducing the risks associated with human space missions. Antarctica may provide an ideal setting for testing critical technologies (habitat design, life support, and advanced scientific instrumentation), studying human factors and physiology, and conducting basic scientific research similar to and directly relevant to that planned for the SEI.

Revised East-West Antarctic plate motions since the Middle Eocene

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Granot, R.; Cande, S. C.; Stock, J.; Damaske, D.

2010-12-01

The middle Cenozoic (43-26 Ma) rifting between East and West Antarctica is defined by an episode of ultraslow seafloor spreading in the Adare Basin, located off northwestern Ross Sea. The absence of fracture zones and the lack of sufficient well-located magnetic anomaly picks have resulted in a poorly constrained kinematic model (Cande et al., 2000). Here we utilize the results from a dense aeromagnetic survey (Damaske et al., 2007) collected as part of GANOVEX IX 2005/06 campaign to re-evaluate the kinematics of the West Antarctic rift system since the Middle Eocene. We identify marine magnetic anomalies (anomalies 12o, 13o, 16y, and 18o) along a total of 25,000 km of the GPS navigated magnetic profiles. The continuation of these anomalies into the Northern Basin has allowed us to use the entire N-S length of this dataset in our calculations. A distinct curvature in the orientation of the spreading axis provides a strong constraint on our calculated kinematic models. The results from two- (East-West Antarctica) and three- (Australia-East Antarctica-West Antarctica) plate solutions agree well and create a cluster of rotation axes located south of the rift system, near the South Pole. These solutions reveal that spreading rate and direction, and therefore motion between East and West Antarctica, were steady between the Middle Eocene and Early Oligocene. Our kinematic solutions confirm the results of Davey and De Santis (2005) that the Victoria Land Basin has accommodated ~95 km of extension since the Middle Eocene. This magnetic pattern also provides valuable constraints on the post-spreading deformation of the Adare Basin (Granot et al., 2010). The Adare Basin has accommodated very little extension since the Late Oligocene (<7 km), but motion has probably increased southward. The details of this younger phase of motion are still crudely constrained.

Tectonic and erosion-driven uplift in the Gamburtsev Subglacial Mountains of East Antarctica

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Ferraccioli, Fausto; Jordan, Tom; Watts, Tony; Bell, Robin; Jamieson, Stewart; Finn, Carol; Damaske, Detlef

2014-05-01

Understanding the mechanisms leading to intraplate mountain building remains a significant challenge in Earth Sciences compared to ranges formed along plate margins. The most enigmatic intraplate mountain range on Earth is the Gamburtsev Subglacial Mountains (GSM) located in the middle of the Precambrian East Antarctic Craton. During the International Polar Year, the AGAP project acquired 120,000 line km of new airborne geophysical data (Bell et al., 2011, Science) and seismological observations (Hansen et al., 2010, EPSL) across central East Antarctica. Models derived from these datasets provide new geophysical perspectives on crustal architecture and possible uplift mechanisms for the enigmatic GSM (Ferraccioli et al., 2011, Nature). The geophysical data define a 2,500-km-long Paleozoic to Mesozoic rift system in East Antarctica surrounding the GSM. A thick high-density lower crustal root is partially preserved beneath the range and has been interpreted as formed during the Proterozoic assembly of East Antarctica. Rifting could have triggered phase/density changes at deep crustal levels, perhaps restoring some of the latent root buoyancy, as well as causing rift-flank uplift. Permian rifting is well-established in the adjacent Lambert Rift, and was followed by Cretaceous strike-slip faulting and transtension associated with Gondwana break-up; this phase may have provided a more recent tectonic trigger for the initial uplift of the modern GSM. The Cretaceous rift-flank uplift model for the Gamburtsevs is appealing because it relates the initiation of intraplate mountain-building to large-scale geodynamic processes that led to the separation of Greater India from East Antarctica. It is also consistent with several geological and geophysical interpretations within the Lambert Rift. However, recent detrital thermochrology results from Oligocene-Quaternary sediments in Prydz Bay (Tochlin et al., 2012, G3) argue against the requirement for major Cretaceous rift

Zhongshania antarctica gen. nov., sp. nov. and Zhongshania guokunii sp. nov., gammaproteobacteria respectively isolated from coastal attached (fast) ice and surface seawater of the Antarctic.

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Li, Hui-Juan; Zhang, Xi-Ying; Chen, Chun-Xiao; Zhang, Yan-Jiao; Gao, Zhao-Ming; Yu, Yong; Chen, Xiu-Lan; Chen, Bo; Zhang, Yu-Zhong

2011-09-01

Two Gram-negative, motile, aerobic, catalase- and oxidase-positive, rod-shaped strains, designated ZS5-23(T) and ZS6-22(T), were respectively isolated from Antarctic coastal attached (fast) ice and surface seawater samples. Both strains could grow at 4-35 °C (optimum 30 °C) and in the absence of NaCl. Analyses of 16S rRNA gene sequences revealed that strains ZS5-23(T) and ZS6-22(T) were closely related to each other (99.0 % sequence similarity) and belonged to the class Gammaproteobacteria, with their closest relatives being Spongiibacter and Melitea species (93.1-94.3 % sequence similarity). The predominant cellular fatty acids in both strains were C₁₇:₁ω8c, C₁₇:₀ and summed feature 3 (C₁₆:₁ω7c and/or iso-C₁₅:₀ 2-OH). Genomic DNA G+C contents of strains ZS5-23(T) and ZS6-22(T) were 51.5 and 51.8 mol%, respectively. The DNA-DNA relatedness between strains ZS5-23(T) and ZS6-22(T) was 50.9 %. Strains ZS5-23(T) and ZS6-22(T) could be differentiated from each other and from Spongiibacter and Melitea species by differences in a number of phenotypic properties. Based on the data presented, strains ZS5-23(T) and ZS6-22(T) represent two novel species in a new genus in the class Gammaproteobacteria, for which the names Zhongshania antarctica gen. nov., sp. nov. (the type species) and Zhongshania guokunii sp. nov. are proposed. The type strain of Zhongshania antarctica is ZS5-23(T) ( = KACC 14066(T)  = CCTCC AB 209246(T)) and that of Zhongshania guokunii is ZS6-22(T) ( = KACC 14532(T)  = CCTCC AB 209247(T)).

Tethered balloons for radio detection of ultra high energy cosmic neutrinos in Antarctica

Energy Technology Data Exchange (ETDEWEB)

Besson, D. [Department of Physics and Astronomy, University of Kansas, Lawrence 66045, KS (United States); Dagkesamanskii, R.; Kravchenko, E. [Radio Astronomy Observatory LPI RAS, Pushchino 142290, Moscow Region (Russian Federation); Kravchenko, I., E-mail: ikrav@cern.ch [Department of Physics and Astronomy, University of Nebraska, Lincoln, 68588, NE (United States); Zheleznykh, I. [Institute for Nuclear Research RAS, Moscow 117312 (Russian Federation)

2012-01-11

We present a brief overview of experimental efforts in Antarctica to search for radio pulses from electron-hadron cascades produced by cosmic ultrahigh-energy neutrinos in Antarctic ice. Thus far, the essential features (energy thresholds, effective recording volumes, etc.) of Antarctic neutrino radio experiments can be classified according to the deployment scheme employed: either (1) on the surface of the glacier - RAMAND-type, (2) in holes in the ice at depths of several hundred meters - RICE-type or (3) on board of a stratospheric balloon at an altitude of 40 km - ANITA-type. We herein propose an alternative possibility, namely to use tethered balloons for placing the radio antennas at modest (compared to ANITA) altitudes above the ice surface (1-2 km). This configuration of antennas will reduce (as compared to ANITA) the energy threshold for detection of neutrinos and increase the observation time.

Tethered balloons for radio detection of ultra high energy cosmic neutrinos in Antarctica

International Nuclear Information System (INIS)

Besson, D.; Dagkesamanskii, R.; Kravchenko, E.; Kravchenko, I.; Zheleznykh, I.

2012-01-01

We present a brief overview of experimental efforts in Antarctica to search for radio pulses from electron-hadron cascades produced by cosmic ultrahigh-energy neutrinos in Antarctic ice. Thus far, the essential features (energy thresholds, effective recording volumes, etc.) of Antarctic neutrino radio experiments can be classified according to the deployment scheme employed: either (1) on the surface of the glacier - RAMAND-type, (2) in holes in the ice at depths of several hundred meters - RICE-type or (3) on board of a stratospheric balloon at an altitude of 40 km - ANITA-type. We herein propose an alternative possibility, namely to use tethered balloons for placing the radio antennas at modest (compared to ANITA) altitudes above the ice surface (1-2 km). This configuration of antennas will reduce (as compared to ANITA) the energy threshold for detection of neutrinos and increase the observation time.

Life form and water source interact to determine active time and environment in cryptogams: an example from the maritime Antarctic.

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Schlensog, Mark; Green, T G Allan; Schroeter, Burkhard

2013-09-01

Antarctica, with its almost pristine conditions and relatively simple vegetation, offers excellent opportunities to investigate the influence of environmental factors on species performance, such information being crucial if the effects of possible climate change are to be understood. Antarctic vegetation is mainly cryptogamic. Cryptogams are poikilohydric and are only metabolically and photosynthetically active when hydrated. Activity patterns of the main life forms present, bryophytes (10 species, ecto- and endohydric), lichens (5 species) and phanerogams (2 species), were monitored for 21 days using chlorophyll a fluorescence as an indicator of metabolic activity and, therefore, of water regime at a mesic (hydration by meltwater) and a xeric (hydration by precipitation) site on Léonie Island/West Antarctic Peninsula (67°36'S). Length of activity depended mainly on site and form of hydration. Plants at the mesic site that were hydrated by meltwater were active for long periods, up to 100 % of the measurement period, whilst activity was much shorter at the xeric site where hydration was entirely by precipitation. There were also differences due to life form, with phanerogams and mesic bryophytes being most active and lichens generally much less so. The length of the active period for lichens was longer than in continental Antarctica but shorter than in the more northern Antarctic Peninsula. Light intensity when hydrated was positively related to the length of the active period. High activity species were strongly coupled to the incident light whilst low activity species were active under lower light levels and essentially uncoupled from incident light. Temperatures were little different between sites and also almost identical to temperatures, when active, for lichens in continental and peninsular Antarctica. Gradients in vegetation cover and growth rates across Antarctica are, therefore, not likely to be due to differences in temperature but more likely to

Ocean acidification changes the structure of an Antarctic coastal protistan community

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A. M. Hancock

2018-04-01

Full Text Available Antarctic near-shore waters are amongst the most sensitive in the world to ocean acidification. Microbes occupying these waters are critical drivers of ecosystem productivity, elemental cycling and ocean biogeochemistry, yet little is known about their sensitivity to ocean acidification. A six-level, dose–response experiment was conducted using 650 L incubation tanks (minicosms adjusted to a gradient in fugacity of carbon dioxide (fCO2 from 343 to 1641 µatm. The six minicosms were filled with near-shore water from Prydz Bay, East Antarctica, and the protistan composition and abundance was determined by microscopy during 18 days of incubation. No CO2-related change in the protistan community composition was observed during the initial 8 day acclimation period under low light. Thereafter, the response of both autotrophic and heterotrophic protists to fCO2 was species-specific. The response of diatoms was mainly cell size related; microplanktonic diatoms ( >  20 µm increased in abundance with low to moderate fCO2 (343–634 µatm but decreased at fCO2  ≥  953 µatm. Similarly, the abundance of Phaeocystis antarctica increased with increasing fCO2 peaking at 634 µatm. Above this threshold the abundance of micro-sized diatoms and P. antarctica fell dramatically, and nanoplanktonic diatoms ( ≤  20 µm dominated, therefore culminating in a significant change in the protistan community composition. Comparisons of these results with previous experiments conducted at this site show that the fCO2 thresholds are similar, despite seasonal and interannual differences in the physical and biotic environment. This suggests that near-shore microbial communities are likely to change significantly near the end of this century if anthropogenic CO2 release continues unabated, with profound ramifications for near-shore Antarctic ecosystem food webs and biogeochemical cycling.

Evidence for differences in the thermal histories of Antarctic and non-Antarctic H chondrites with cosmic-ray exposure ages less than 20 Ma

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Sears, Derek W. G.; Benoit, Paul; Batchelor, J. David

1991-01-01

Antarctic H chondrites show a different range of induced thermoluminescence properties compared with those of H chondrites that have fallen elsewhere in the world. Recent noble gas data of Schultz et al. (1991) show that this difference is displayed most dramatically by meteorites with cosmic-ray exposure ages less than 20 Ma, and they confirm that the differences cannot be attributed to weathering or to the presence of a great many fragments of an unusual Antarctic meteorite. Annealing experiments on an H5 chondrite, and other measurements on a variety of ordinary chondrites, have shown that induced TL properties are sensitive to the thermal histories of the meteorities. It is concluded that the events(s) that released the less than 20 Ma samples, which are predominantly those with exposure ages of 8 + or - 2 Ma, produced two groups with different thermal histories, one that came to earth several 100,000 years ago and that are currently only found in Antarctica, and one that is currently falling on the earth.

Diversity of bacteria producing pigmented colonies in aerosol, snow and soil samples from remote glacial areas (Antarctica, Alps and Andes)

Science.gov (United States)

González-Toril, E.; Amils, R.; Delmas, R. J.; Petit, J.-R.; Komárek, J.; Elster, J.

2008-04-01

Four different communities and one culture of pigmented microbial assemblages were obtained by incubation in mineral medium of samples collected from high elevation snow in the Alps (Mt. Blanc area) and the Andes (Nevado Illimani summit, Bolivia), from Antarctic aerosol (French station Dumont d'Urville) and a maritime Antarctic soil (King George Island, South Shetlands, Uruguay Station Artigas). Molecular analysis of more than 200 16S rRNA gene sequences showed that all cultured cells belong to the Bacteria domain. The phylogenetic comparison with the currently available rDNA database allowed the identification of sequences belonging to Proteobacteria (Alpha-, Beta- and Gamma-proteobacteria), Actinobacteria and Bacteroidetes phyla. The Andes snow culture was the richest in bacterial diversity (eight microorganisms identified) and the maritime Antarctic soil the poorest (only one). Snow samples from Col du midi (Alps) and the Andes shared the highest number of identified microorganisms (Agrobacterium, Limnobacter, Aquiflexus and two uncultured Alphaproteobacteria clones). These two sampling sites also shared four sequences with the Antarctic aerosol sample (Limnobacter, Pseudonocardia and an uncultured Alphaproteobacteria clone). The only microorganism identified in the maritime Antarctica soil (Brevundimonas sp.) was also detected in the Antarctic aerosol. The two snow samples from the Alps only shared one common microorganism. Most of the identified microorganisms have been detected previously in cold environments (Dietzia kujamenisi, Pseudonocardia Antarctica, Hydrogenophaga palleronii and Brebundimonas sp.), marine sediments (Aquiflexus balticus, Pseudomonas pseudoalkaligenes, Pseudomonas sp. and one uncultured Alphaproteobacteria), and soils and rocks (Pseudonocardia sp., Agrobactrium sp., Limnobacter sp. and two uncultured Alphaproteobacetria clones). Air current dispersal is the best model to explain the presence of very specific microorganisms, like those

Absorption of ultraviolet radiation by antarctic phytoplankton

Energy Technology Data Exchange (ETDEWEB)

Vernet, M.; Mitchell, B.G. (Univ. of California-San Diego, La Jolla (United States))

1990-01-09

Antarctic phytoplankton contain UV-absorbing compounds that may block damaging radiation. Compounds that absorb from 320-340 nm were observed in spectral absorption of both particulates and in methanol extracts of the particulates. The decrease in the total concentration of these UV compounds with respect to chlorophyll a, as measured by the ratio of in vitro absorption at 335 nm to absorption at 665 nm is variable and decreases with depth. We observed up to 5-fold decrease in this ratio for samples within the physically mixes surface layer. The absorption of UV radiation in methanol extracts, which peaks from 320 to 340 nm, may be composed of several compounds. Shifts in peak absorption with depth (for example, from 331 nm at surface to 321 nm at 75 m), may be interpreted as a change in composition. Ratios of protective yellow xanthophylls (diadinoxanthin + diatoxanthin) to photosynthetic fucoxanthin-like pigments have highest values in surface waters. As these pigments also absorb in the near UV, their function might extend to protection as well as utilization of UV radiation for photosynthesis. We document strong absorption in the UV from 320-330 nm for Antarctic marine particulates. Below this region of the solar energy spectrum, absolute energy levels of incident radiation drop off dramatically. Only wavelengths shorter than about 320 nm will be significantly enhanced due to ozone depletion. If the absorption we observed serves a protective role for phytoplankton photosynthesis, it appears the peak band is in the region where solar energy increases rapidly, and not in the region where depletion would cause significant variations in absolute flux.

Testing oils in antarctic soils

International Nuclear Information System (INIS)

Leufkens, D.

2001-01-01

The resident seals, whales and penguins in Antarctica's Ross Sea region have only environmentally friendly ways of getting around. In contrast, wherever humans go in the Antarctic and whatever they do, be it research, tourism or fishing, they need fuel for their planes, icebreaker ships, land vehicles and generators. Because of this, petroleum hydrocarbons are the most likely source of pollution in the Antarctic. Accidental oil spills often occur near scientific stations, where storage and refuelling of aircraft and vehicles can result in spills. Spills also occur as a consequence of drilling activities. Dr Jackie Aislabie, a microbiologist from the New Zealand government's research company Landcare Research, is leading a program aimed at understanding how oil spills impact on Antarctic soils. The properties of pristine soils were compared with oil-contaminated soil at three locations: Scott Base, Marble Point and in the Wright Valley at Bull Pass. Soils in the Scott Base area are impacted by the establishment and continuous habitation of the base over 40 years, and a hydrocarbon-contaminated site was sampled near a former storage area for drums of mixed oils. Soil sampled from Marble Point was taken from near the old Marble Point camp, which was inhabited from 1957 to about 1963. Oil stains were visible on the soil surface, and are assumed to have been there for more than 30 years. The samples selected for analysis from the Wright Valley came from a spill site near Bull Pass that occurred during seismic bore-hole drilling activities in 1985. The contamination levels ranged from below detection to just over 29,000 μg/g of soil. Descriptions and analyse results are included into a Geographic Information System and associated soils database

Testing and data reduction of the Chinese Small Telescope Array (CSTAR) for Dome A, Antarctica

International Nuclear Information System (INIS)

Zhou Xu; Wu Zhenyu; Jiang Zhaoji; Hu Jingyao; Li Qisheng; Ma Jun; Wang Jiali; Wu Jianghua; Yan Jun; Cui Xiangqun; Gong Xuefei; Liu Genrong; Xia Lirong; Yuan Xiangyan; Zhai Fengxiang; Zhang Ru; Feng Longlong; Wang Lifan; Zhu Zhenxi

2010-01-01

The Chinese Small Telescope Array (CSTAR) is the first Chinese astronomical instrument on the Antarctic ice cap. The low temperature and low pressure testing of the data acquisition system was carried out in a laboratory refrigerator and on the 4500 m Pamirs high plateau, respectively. The results from the final four nights of test observations demonstrated that CSTAR was ready for operation at Dome A, Antarctica. In this paper, we present a description of CSTAR and the performance derived from the test observations.

Emperors in hiding: when ice-breakers and satellites complement each other in Antarctic exploration.

Science.gov (United States)

Ancel, André; Cristofari, Robin; Fretwell, Peter T; Trathan, Phil N; Wienecke, Barbara; Boureau, Matthieu; Morinay, Jennifer; Blanc, Stéphane; Le Maho, Yvon; Le Bohec, Céline

2014-01-01

Evaluating the demographic trends of marine top predators is critical to understanding the processes involved in the ongoing rapid changes in Antarctic ecosystems. However, the remoteness and logistical complexity of operating in Antarctica, especially during winter, make such an assessment difficult. Satellite imaging is increasingly recognised as a valuable method for remote animal population monitoring, yet its accuracy and reliability are still to be fully evaluated. We report here the first ground visit of an emperor penguin colony first discovered by satellite, but also the discovery of a second one not indicated by satellite survey at that time. Several successive remote surveys in this coastal region of East Antarctica, both before and after sudden local changes, had indeed only identified one colony. These two colonies (with a total of ca. 7,400 breeding pairs) are located near the Mertz Glacier in an area that underwent tremendous habitat change after the glacier tongue broke off in February 2010. Our findings therefore suggest that a satellite survey, although offering a major advance since it allows a global imaging of emperor penguin colonies, may miss certain colony locations when challenged by certain features of polar ecosystems, such as snow cover, evolving ice topology, and rapidly changing habitat. Moreover our survey shows that this large seabird has considerable potential for rapid adaptation to sudden habitat loss, as the colony detected in 2009 may have moved and settled on new breeding grounds. Overall, the ability of emperor penguin colonies to relocate following habitat modification underlines the continued need for a mix of remote sensing and field surveys (aerial photography and ground counts), especially in the less-frequented parts of Antarctica, to gain reliable knowledge about the population demography and dynamics of this flagship species of the Antarctic ecosystem.

Emperors in hiding: when ice-breakers and satellites complement each other in Antarctic exploration.

Directory of Open Access Journals (Sweden)

André Ancel

Full Text Available Evaluating the demographic trends of marine top predators is critical to understanding the processes involved in the ongoing rapid changes in Antarctic ecosystems. However, the remoteness and logistical complexity of operating in Antarctica, especially during winter, make such an assessment difficult. Satellite imaging is increasingly recognised as a valuable method for remote animal population monitoring, yet its accuracy and reliability are still to be fully evaluated. We report here the first ground visit of an emperor penguin colony first discovered by satellite, but also the discovery of a second one not indicated by satellite survey at that time. Several successive remote surveys in this coastal region of East Antarctica, both before and after sudden local changes, had indeed only identified one colony. These two colonies (with a total of ca. 7,400 breeding pairs are located near the Mertz Glacier in an area that underwent tremendous habitat change after the glacier tongue broke off in February 2010. Our findings therefore suggest that a satellite survey, although offering a major advance since it allows a global imaging of emperor penguin colonies, may miss certain colony locations when challenged by certain features of polar ecosystems, such as snow cover, evolving ice topology, and rapidly changing habitat. Moreover our survey shows that this large seabird has considerable potential for rapid adaptation to sudden habitat loss, as the colony detected in 2009 may have moved and settled on new breeding grounds. Overall, the ability of emperor penguin colonies to relocate following habitat modification underlines the continued need for a mix of remote sensing and field surveys (aerial photography and ground counts, especially in the less-frequented parts of Antarctica, to gain reliable knowledge about the population demography and dynamics of this flagship species of the Antarctic ecosystem.

Inter-annual variability of surface ozone at coastal (Dumont d'Urville, 2004–2014 and inland (Concordia, 2007–2014 sites in East Antarctica

Directory of Open Access Journals (Sweden)

M. Legrand

2016-07-01

Full Text Available Surface ozone has been measured since 2004 at the coastal East Antarctic site of Dumont d'Urville (DDU, and since 2007 at the Concordia station located on the high East Antarctic plateau. This paper discusses long-term changes, seasonal and diurnal cycles, as well as inter-annual summer variability observed at these two East Antarctic sites. At Concordia, near-surface ozone data were complemented by balloon soundings and compared to similar measurements done at the South Pole. The DDU record is compared to those obtained at the coastal site of Syowa, also located in East Antarctica, as well as the coastal sites of Neumayer and Halley, both located on the coast of the Weddell Sea in West Antarctica. Surface ozone mixing ratios exhibit very similar seasonal cycles at Concordia and the South Pole. However, in summer the diurnal cycle of ozone is different at the two sites with a drop of ozone in the afternoon at Concordia but not at the South Pole. The vertical distribution of ozone above the snow surface also differs. When present, the ozone-rich layer located near the ground is better mixed and deeper at Concordia (up to 400 m than at the South Pole during sunlight hours. These differences are related to different solar radiation and wind regimes encountered at these two inland sites. DDU appears to be the coastal site where the impact of the late winter/spring bromine chemistry is the weakest, but where the impact of elevated ozone levels caused by NOx snow emissions from the high Antarctic plateau is the highest. The highest impact of the bromine chemistry is seen at Halley and Neumayer, and to a lesser extent at Syowa. These three sites are only weakly impacted by the NOx chemistry and the net ozone production occurring on the high Antarctic plateau. The differences in late winter/spring are attributed to the abundance of sea ice offshore from the sites, whereas those in summer are related to the topography of East Antarctica that promotes

Penguin Proxies: Deciphering Millennial-Scale Antarctic Ecosystem Change using Amino Acid Stable Isotope Analysis.

Science.gov (United States)

Michelson, C.; McMahon, K.; Emslie, S. D.; Patterson, W. P.; McCarthy, M. D.; Polito, M. J.

2017-12-01

The Southern Ocean ecosystem is undergoing rapid environmental change due to ongoing and historic anthropogenic impacts such as climate change and marine mammal harvesting. These disturbances may have cascading effects through the Antarctic food webs, resulting in profound shifts in the sources and cycling of organic matter supporting higher-trophic organisms, such as penguins. For example, bulk stable isotope analyses of modern and ancient preserved penguin tissues suggest variations in penguin feeding ecology throughout the Holocene with dramatic isotopic shifts in the last 200 years. However, it is not clear whether these isotopic shifts resulted from changes at the base of the food web, dietary shifts in penguins, or some combination of both factors. Newly developed compound-specific stable nitrogen isotope analysis of individual amino acids (CSIA-AA) may provide a powerful new tool to tease apart these confounding variables. Stable nitrogen isotope values of trophic amino acids (e.g., glutamic acid) increase substantially with each trophic transfer in the food web, while source amino acid (e.g., phenylalanine) stable nitrogen isotope values remain relatively unchanged and reflect ecosystem baselines. As such, we can use this CSIA-AA approach to decipher between baseline and dietary shifts in penguins over time from modern and ancient eggshells of Pygoscelis penguins in the Antarctic Peninsula and the Ross Sea regions of Antarctica. In order to accurately apply this CSIA-AA approach, we first characterized the trophic fractionation factors of individual amino acids between diet and penguin consumers in a long-term controlled penguin feeding experiment. We then applied these values to modern and ancient eggshells from the Antarctic Peninsula and Ross Sea to evaluate shifts in penguin trophic dynamics as a function of climate and anthropogenic interaction throughout much of the Holocene. This work develops a cutting edge new molecular geochemistry approach

Research of remote control for Chinese Antarctica Telescope based on iridium satellite communication

Science.gov (United States)

Xu, Lingzhe; Yang, Shihai

2010-07-01

Astronomers are ever dreaming of sites with best seeing on the Earth surface for celestial observation, and the Antarctica is one of a few such sites only left owing to the global air pollution. However, Antarctica region is largely unaccessible for human being due to lacking of fundamental living conditions, travel facilities and effective ways of communication. Worst of all, the popular internet source as a general way of communication scarcely exists there. Facing such a dilemma and as a solution remote control and data transmission for telescopes through iridium satellite communication has been put forward for the Chinese network Antarctic Schmidt Telescopes 3 (AST3), which is currently under all round research and development. This paper presents iridium satellite-based remote control application adapted to telescope control. The pioneer work in China involves hardware and software configuration utilizing techniques for reliable and secure communication, which is outlined in the paper too.

The behaviour of residual contaminants at a former station site, Antarctica

International Nuclear Information System (INIS)

Webster, Jenny; Webster, Kerry; Nelson, Peter; Waterhouse, Emma

2003-01-01

Minor contamination by metals, phosphorus, and fuel products were found at a former research station site in Antarctica. - In 1994, New Zealand's only mainland Antarctic base, Vanda Station, was removed from the shores of Lake Vanda, in the McMurdo Dry Valleys region of southern Victoria Land, Antarctica. Residual chemical contamination of the station site has been identified, in the form of discrete fuel spills, locally elevated Pb, Zn, Ag and Cd concentrations in soil and elevated Cu, Ni, Co and phosphate concentrations in suprapermafrost fluids in a gully formerly used for domestic washing water disposal. Pathways for contaminant transfer to Lake Vanda, potential environmental impacts and specific remediation/monitoring options are considered. While some contaminants (particularly Zn) could be selectively leached from flooded soil, during a period of rising lake level, the small area of contaminated soils exposed and low level of contamination suggests that this would not adversely affect either shallow lake water quality or the growth of cyanobacteria. Phosphate-enhanced growth of the latter may, however, be a visible consequence of the minor contamination occurring at this site

Comprehensive analysis of an Antarctic bacterial community with the adaptability of growth at higher temperatures than those in Antarctica.

Science.gov (United States)

Hosoi-Tanabe, Shoko; Zhang, Hongyan; Zhu, Daochen; Nagata, Shinichi; Ban, Syuhei; Imura, Satoshi

2010-06-01

To investigate the adaptability to higher temperatures of Antarctic microorganisms persisting in low temperature conditions for a long time, Antarctic lake samples were incubated in several selection media at 25 degrees C and 30 degrees C. The microorganisms did not grow at 30 degrees C; however, some of them grew at 25 degrees C, indicating that the bacteria in Antarctic have the ability to grow at a wide range of temperatures. Total DNA was extracted from these microorganisms and amplified using the bacteria-universal primers. The amplified fragments were cloned, and randomly selected 48 clones were sequenced. The sequenced clones showed high similarity to the alpha-subdivision of the Proteobacteria with specific affinity to the genus Agrobacterium, Caulobacter and Brevundimonas, the ss-subdivision of Proteobacteria with specific affinity to the genus Cupriavidus, and Bacillus of the phylum Firmicutes. These results showed the presence of universal genera, suggesting that the bacteria in the Antarctic lake were not specific to this environment.

Design of a seismo-acoustic station for Antarctica

Science.gov (United States)

Contrafatto, Danilo; Fasone, Rosario; Ferro, Angelo; Larocca, Graziano; Laudani, Giuseppe; Rapisarda, Salvatore; Scuderi, Luciano; Zuccarello, Luciano; Privitera, Eugenio; Cannata, Andrea

2018-04-01

In recent years, seismological studies in Antarctica have contributed plenty of new knowledge in many fields of earth science. Moreover, acoustic investigations are now also considered a powerful tool that provides insights for many different objectives, such as analyses of regional climate-related changes and studies of volcanic degassing and explosive activities. However, installation and maintenance of scientific instrumentation in Antarctica can be really challenging. Indeed, the instruments have to face the most extreme climate on the planet. They must be tolerant of very low temperatures and robust enough to survive strong winds. Moreover, one of the most critical tasks is powering a remote system year-round at polar latitudes. In this work, we present a novel seismo-acoustic station designed to work reliably in polar regions. To enable year-round seismo-acoustic data collection in such a remote, extreme environment, a hybrid powering system is used, integrating solar panels, a wind generator, and batteries. A power management system was specifically developed to either charge the battery bank or divert energy surplus to warm the enclosure or release the excess energy to the outside environment. Finally, due to the prohibitive environmental conditions at most Antarctic installation sites, the station was designed to be deployed quickly.

Gene expression changes governing extreme dehydration tolerance in an Antarctic insect

Science.gov (United States)

Teets, Nicholas M.; Peyton, Justin T.; Colinet, Herve; Renault, David; Kelley, Joanna L.; Kawarasaki, Yuta; Lee, Richard E.; Denlinger, David L.

2012-01-01

Among terrestrial organisms, arthropods are especially susceptible to dehydration, given their small body size and high surface area to volume ratio. This challenge is particularly acute for polar arthropods that face near-constant desiccating conditions, as water is frozen and thus unavailable for much of the year. The molecular mechanisms that govern extreme dehydration tolerance in insects remain largely undefined. In this study, we used RNA sequencing to quantify transcriptional mechanisms of extreme dehydration tolerance in the Antarctic midge, Belgica antarctica, the world’s southernmost insect and only insect endemic to Antarctica. Larvae of B. antarctica are remarkably tolerant of dehydration, surviving losses up to 70% of their body water. Gene expression changes in response to dehydration indicated up-regulation of cellular recycling pathways including the ubiquitin-mediated proteasome and autophagy, with concurrent down-regulation of genes involved in general metabolism and ATP production. Metabolomics results revealed shifts in metabolite pools that correlated closely with changes in gene expression, indicating that coordinated changes in gene expression and metabolism are a critical component of the dehydration response. Finally, using comparative genomics, we compared our gene expression results with a transcriptomic dataset for the Arctic collembolan, Megaphorura arctica. Although B. antarctica and M. arctica are adapted to similar environments, our analysis indicated very little overlap in expression profiles between these two arthropods. Whereas several orthologous genes showed similar expression patterns, transcriptional changes were largely species specific, indicating these polar arthropods have developed distinct transcriptional mechanisms to cope with similar desiccating conditions. PMID:23197828

The internal layering of Pine Island Glacier, West Antarctica, from airborne radar-sounding data

DEFF Research Database (Denmark)

Karlsson, Nanna Bjørnholt; Rippin, David; Vaughan, David

2010-01-01

This paper presents an overview of internal layering across Pine Island Glacier, West Antarctica, as measured from airborne-radar data acquired during a survey conducted by the British Antarctic Survey and the University of Texas in the 2004/05 season. Internal layering is classified according...... to type (continuous/discontinuous/missing) and the results compared with InSAR velocities. Several areas exhibit disruption of internal layers that is most likely caused by large basal shear stresses. Signs of changes in flow were identified in a few inter-tributary areas, but overall the layering...

Eocene relatives of cod icefishes (Perciformes: Notothenioidei) from Seymour Island, Antarctica

DEFF Research Database (Denmark)

Bieńkowska-Wasiluk, Małgorzata; Bonde, Niels Christensøn; Møller, Peter Rask

2013-01-01

Fragmentary skull bones and vertebra from the Upper Eocene La Meseta Formation on Seymour (Marambio) Island, Antarctic Peninsula have been described as gadiform fishes, informally named “Mesetaichthys”. Here we describe jaws as Mesetaichthys jerzmanskae n. g. and n. sp., and refer this taxon...... to the perciform suborder Notothenioidei. This group is almost unknown as fossils. Similarities to the living, ‘primitive’ nototheniid Dissostichus eleginoides are indicated in the dentition. Gadiform evolution in the Paleocene-Eocene, and the possibility of a correlation between the origin and evolution...... of notothenioids in connection with the deterioration of the climate in Antarctica during the Late Eocene-Oligocene is discussed....

Interlaboratory comparison of {sup 10}Be concentrations in two ice cores from Central West Antarctica

Energy Technology Data Exchange (ETDEWEB)

Woodruff, Thomas E., E-mail: woodruft@purdue.edu [PRIME Laboratory, Purdue University, West Lafayette, IN 47907 (United States); Welten, Kees C. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Caffee, Marc W. [PRIME Laboratory, Purdue University, West Lafayette, IN 47907 (United States); Nishiizumi, Kunihiko [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)

2013-01-15

To improve sample processing efficiency for cosmogenic radionuclide measurements in samples from the West Antarctic Ice Sheet Divide core, two chemical lines, one at Purdue University and one at University of California, Berkeley, are being used. Sections from two shallow ice cores from West Antarctica were processed at each lab, while all {sup 10}Be accelerator mass spectrometry measurements were performed at PRIME Lab, Purdue University. Duplicate samples gave {sup 10}Be results that are identical to within the AMS measurement uncertainties of 2-3%.

The Antarctica component of postglacial rebound model ICE-6G_C (VM5a) based on GPS positioning, exposure age dating of ice thicknesses, and relative sea level histories

Science.gov (United States)

Argus, Donald F.; Peltier, W. R.; Drummond, R.; Moore, Angelyn W.

2014-07-01

A new model of the deglaciation history of Antarctica over the past 25 kyr has been developed, which we refer to herein as ICE-6G_C (VM5a). This revision of its predecessor ICE-5G (VM2) has been constrained to fit all available geological and geodetic observations, consisting of: (1) the present day uplift rates at 42 sites estimated from GPS measurements, (2) ice thickness change at 62 locations estimated from exposure-age dating, (3) Holocene relative sea level histories from 12 locations estimated on the basis of radiocarbon dating and (4) age of the onset of marine sedimentation at nine locations along the Antarctic shelf also estimated on the basis of 14C dating. Our new model fits the totality of these data well. An additional nine GPS-determined site velocities are also estimated for locations known to be influenced by modern ice loss from the Pine Island Bay and Northern Antarctic Peninsula regions. At the 42 locations not influenced by modern ice loss, the quality of the fit of postglacial rebound model ICE-6G_C (VM5A) is characterized by a weighted root mean square residual of 0.9 mm yr-1. The Southern Antarctic Peninsula is inferred to be rising at 2 mm yr-1, requiring there to be less Holocene ice loss there than in the prior model ICE-5G (VM2). The East Antarctica coast is rising at approximately 1 mm yr-1, requiring ice loss from this region to have been small since Last Glacial Maximum. The Ellsworth Mountains, at the base of the Antarctic Peninsula, are inferred to be rising at 5-8 mm yr-1, indicating large ice loss from this area during deglaciation that is poorly sampled by geological data. Horizontal deformation of the Antarctic Plate is minor with two exceptions. First, O'Higgins, at the tip of the Antarctic Peninsula, is moving southeast at a significant 2 mm yr-1 relative to the Antarctic Plate. Secondly, the margins of the Ronne and Ross Ice Shelves are moving horizontally away from the shelf centres at an approximate rate of 0.8 mm yr-1, in

Occurrence of Legacy and New Persistent Organic Pollutants in Avian Tissues from King George Island, Antarctica.

Science.gov (United States)

Kim, Jun-Tae; Son, Min-Hui; Kang, Jung-Ho; Kim, Jeong-Hoon; Jung, Jin-Woo; Chang, Yoon-Seok

2015-11-17

Legacy and new persistent organic pollutants (POPs), including polychlorinated naphthalenes (PCNs), Dechlorane Plus (DPs) and related compounds (Dechloranes), hexabromocyclododecanes (HBCDs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs), were analyzed in avian tissue samples from King George Island, Antarctica. The avian species consisted of the Gentoo penguin (Pygoscelis papua), the Adelie penguin (Pygoscelis adeliae), the South polar skua (Stercorarius maccormicki), and the Brown skua (Stercorarius antarcticus). HBCDs were detected in all samples and ranged from 1.67-713 pg/g-lipid. In the penguin samples, the concentrations of PCNs ranged from 0.69-2.07 ng/g-lipid, whereas those in the skua samples ranged from 7.41-175 ng/g-lipid. The levels of Dechloranes ranged from 0.60-1.30 ng/g-lipid in the penguin samples and from 6.57-47.4 ng/g-lipid in the skua samples. The concentrations and congener distributions of OCPs and PCBs were similar to the results of previous reports. The three new POPs were detected in all samples, and this study was one of the first reports on the occurrence of these pollutants in the Antarctic biota. Because Antarctica is one of the most pristine places on Earth, the detection of new POPs in the Antarctic birds, especially penguins, is direct evidence of the long-range transport of pollutants. Furthermore, the concentration ratios of the penguin to the skua samples (BMFs-p) were greater than 1 in most legacy and new POPs, and the BMFs-p values of the new POPs were comparable to those of some OCPs, suggesting a possibility of biomagnification. Despite the small sample size, the results of this study identified POP contamination of the Antarctic avian species and long-range transport and biomagnification of HBCDs, Dechloranes, and PCNs.

Application of ground-penetrating radar at McMurdo Station, Antarctica

Energy Technology Data Exchange (ETDEWEB)

Stefano, J.E.

1992-01-01

Argonne National Laboratory initiated a site investigation program at McMurdo Station, Antarctica, to characterize environmental contamination. The performance and usefulness of ground-penetrating radar (GPR) was evaluated under antarctic conditions during the initial site investigation in January 1991. Preliminary surveys were successful in defining the contact between reworked pyroclastic material and in the prefill, undisturbed pyroclastics and basalts at some sites. Interference from radio traffic at McMurdo Station was not observed, but interference was a problem in work with unshielded antennas near buildings. In general, the results of this field test suggest that high-quality, high-resolution, continuous subsurface profiles can be produced with GPR over most of McMurdo Station.

Application of ground-penetrating radar at McMurdo Station, Antarctica

Energy Technology Data Exchange (ETDEWEB)

Stefano, J.E.

1992-05-01

Argonne National Laboratory initiated a site investigation program at McMurdo Station, Antarctica, to characterize environmental contamination. The performance and usefulness of ground-penetrating radar (GPR) was evaluated under antarctic conditions during the initial site investigation in January 1991. Preliminary surveys were successful in defining the contact between reworked pyroclastic material and in the prefill, undisturbed pyroclastics and basalts at some sites. Interference from radio traffic at McMurdo Station was not observed, but interference was a problem in work with unshielded antennas near buildings. In general, the results of this field test suggest that high-quality, high-resolution, continuous subsurface profiles can be produced with GPR over most of McMurdo Station.

Application of ground-penetrating radar at McMurdo Station, Antarctica

International Nuclear Information System (INIS)

Stefano, J.E.

1992-01-01

Argonne National Laboratory initiated a site investigation program at McMurdo Station, Antarctica, to characterize environmental contamination. The performance and usefulness of ground-penetrating radar (GPR) was evaluated under antarctic conditions during the initial site investigation in January 1991. Preliminary surveys were successful in defining the contact between reworked pyroclastic material and in the prefill, undisturbed pyroclastics and basalts at some sites. Interference from radio traffic at McMurdo Station was not observed, but interference was a problem in work with unshielded antennas near buildings. In general, the results of this field test suggest that high-quality, high-resolution, continuous subsurface profiles can be produced with GPR over most of McMurdo Station

Genetic and Molecular Epidemiological Characterization of a Novel Adenovirus in Antarctic Penguins Collected between 2008 and 2013.

Directory of Open Access Journals (Sweden)

Sook-Young Lee

Full Text Available Antarctica is considered a relatively uncontaminated region with regard to the infectious diseases because of its extreme environment, and isolated geography. For the genetic characterization and molecular epidemiology of the newly found penguin adenovirus in Antarctica, entire genome sequencing and annual survey of penguin adenovirus were conducted. The entire genome sequences of penguin adenoviruses were completed for two Chinstrap penguins (Pygoscelis antarctica and two Gentoo penguins (Pygoscelis papua. The whole genome lengths and G+C content of penguin adenoviruses were found to be 24,630-24,662 bp and 35.5-35.6%, respectively. Notably, the presence of putative sialidase gene was not identified in penguin adenoviruses by Rapid Amplification of cDNA Ends (RACE-PCR as well as consensus specific PCR. The penguin adenoviruses were demonstrated to be a new species within the genus Siadenovirus, with a distance of 29.9-39.3% (amino acid, 32.1-47.9% in DNA polymerase gene, and showed the closest relationship with turkey adenovirus 3 (TAdV-3 in phylogenetic analysis. During the 2008-2013 study period, the penguin adenoviruses were annually detected in 22 of 78 penguins (28.2%, and the molecular epidemiological study of the penguin adenovirus indicates a predominant infection in Chinstrap penguin population (12/30, 40%. Interestingly, the genome of penguin adenovirus could be detected in several internal samples, except the lymph node and brain. In conclusion, an analysis of the entire adenoviral genomes from Antarctic penguins was conducted, and the penguin adenoviruses, containing unique genetic character, were identified as a new species within the genus Siadenovirus. Moreover, it was annually detected in Antarctic penguins, suggesting its circulation within the penguin population.

Stable isotopes of carbon dioxide in the marine atmosphere along a hemispheric course from China to Antarctica

Science.gov (United States)

Chen, Qingqing; Zhu, Renbin; Xu, Hua

2013-12-01

During the 24th Chinese Antarctic Expedition, the air samples were collected at 10:00 and 22:00 (local time) along the track of ship “Xuelong” from Shanghai Harbor, China to Antarctica. Carbon dioxide (CO2) concentrations and its isotopic compositions were measured in these samples. Mean CO2 concentration at 22:00 (419.4 ± 27.1 ppmv) was higher than that at 10:00 (392.7 ± 20.0 ppmv), whereas δ13C-CO2 values at 22:00 (-8.58 ± 0.47‰) were lower than those at 10:00 (-8.23 ± 0.49‰), indicating that the 13C/12C ratio might be associated with the photosynthesis and respiration of terrestrial or marine organisms during the diurnal cycle. Overall the mean δ13C- and δ18O-CO2 were -8.39 ± 0.51‰ and 0.03 ± 1.39‰, respectively, from 30°N to 69°S, and the δ13C significantly negatively correlated with δ18O-CO2. A small but progressive increase in δ13C values with increasing latitudes southward was in good agreement with the expected trend. The enhanced CO2 concentrations occurred in the atmosphere close to Eurasia continent, Philippines, Malaysia and Indonesia, and the δ13C oscillations agreed well with anthropogenic pollution. In the range of 30°S-50°S, CO2 concentrations were generally low with relatively stable δ13C and δ18O values. In Antarctic Convergence Zone, a great difference of δ13C occurred between 10:00 and 22:00, and atmospheric CO2 was significantly depleted in 13C at 22:00. Our results indicated that the isotopic compositions of CO2 in the marine atmosphere might be a sensitive indicator for the strength of CO2 source and sink from the ocean.

ACCURACY ASSESSMENT OF RECENT GLOBAL OCEAN TIDE MODELS AROUND ANTARCTICA

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J. Lei

2017-09-01

Full Text Available Due to the coverage limitation of T/P-series altimeters, the lack of bathymetric data under large ice shelves, and the inaccurate definitions of coastlines and grounding lines, the accuracy of ocean tide models around Antarctica is poorer than those in deep oceans. Using tidal measurements from tide gauges, gravimetric data and GPS records, the accuracy of seven state-of-the-art global ocean tide models (DTU10, EOT11a, GOT4.8, FES2012, FES2014, HAMTIDE12, TPXO8 is assessed, as well as the most widely-used conventional model FES2004. Four regions (Antarctic Peninsula region, Amery ice shelf region, Filchner-Ronne ice shelf region and Ross ice shelf region are separately reported. The standard deviations of eight main constituents between the selected models are large in polar regions, especially under the big ice shelves, suggesting that the uncertainty in these regions remain large. Comparisons with in situ tidal measurements show that the most accurate model is TPXO8, and all models show worst performance in Weddell sea and Filchner-Ronne ice shelf regions. The accuracy of tidal predictions around Antarctica is gradually improving.

Accuracy Assessment of Recent Global Ocean Tide Models around Antarctica

Science.gov (United States)

Lei, J.; Li, F.; Zhang, S.; Ke, H.; Zhang, Q.; Li, W.

2017-09-01

Due to the coverage limitation of T/P-series altimeters, the lack of bathymetric data under large ice shelves, and the inaccurate definitions of coastlines and grounding lines, the accuracy of ocean tide models around Antarctica is poorer than those in deep oceans. Using tidal measurements from tide gauges, gravimetric data and GPS records, the accuracy of seven state-of-the-art global ocean tide models (DTU10, EOT11a, GOT4.8, FES2012, FES2014, HAMTIDE12, TPXO8) is assessed, as well as the most widely-used conventional model FES2004. Four regions (Antarctic Peninsula region, Amery ice shelf region, Filchner-Ronne ice shelf region and Ross ice shelf region) are separately reported. The standard deviations of eight main constituents between the selected models are large in polar regions, especially under the big ice shelves, suggesting that the uncertainty in these regions remain large. Comparisons with in situ tidal measurements show that the most accurate model is TPXO8, and all models show worst performance in Weddell sea and Filchner-Ronne ice shelf regions. The accuracy of tidal predictions around Antarctica is gradually improving.

Surface Flux Measurements at King Sejong Station in West Antarctica

Science.gov (United States)

Choi, T.; Lee, B.; Lee, H.; Shim, J.

2004-12-01

The Antarctic Peninsula is important in terms of global warming research due to pronounced increase of air temperature over the last century. The first eddy covariance system was established and turbulent fluxes of heat, water vapor, CO2 and momentum have been measured at King Sejong Station (62 \\deg 13øØS, 58 \\deg 47øØW) located in the northern edge of the Antarctic Peninsula since December in 2002. Our objectives are to better understand the interactions between the Antarctic land surface and the atmosphere and to test the feasibility of the long-term operation of eddy covariance system under extreme weather conditions. Various lichens cover the study area and the dominant species is Usnea fasciata-Himantormia. Based on the analyses on turbulent statistics such as integral turbulence characteristics of vertical velocity (w) and heat (T), stationarity test and investigation of correlation coefficient, they follow the Monin-Obukhov similarity and eddy covariance flux data were reliable. About 50 % of total retrieved sensible heat flux data could be used for further analysis. We will report on seasonal variations of energy and mass fluxes and environmental variables. In addition, factors controlling these fluxes will be presented. Acknowledgement: This study was supported by ¡rEnvironmental Monitoring on Human Impacts at the King Sejong Station, Antarctica¡_ (Project PP04102 of Korea Polar Research Institute) and ¡rEco-technopia 21 project¡_ (Ministry of Environment of Korea).

Biogeochemical and microbial variation across 5500 km of Antarctic surface sediment implicates organic matter as a driver of benthic community structure

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Deric R Learman

2016-03-01

Full Text Available Western Antarctica, one of the fastest warming locations on Earth, is a unique environment that is underexplored with regards to biodiversity. Although pelagic microbial communities in the Southern Ocean and coastal Antarctic waters have been well studied, there are fewer investigations of benthic communities and most have a focused geographic range. We sampled surface sediment from 24 sites across a 5,500 km region of Western Antarctica (covering the Ross Sea to the Weddell Sea to examine relationships between microbial communities and sediment geochemistry. Sequencing of the 16S and 18S rRNA genes showed microbial communities in sediments from the Antarctic Peninsula (AP and Western Antarctica (WA, including the Ross, Amundsen, and Bellingshausen Seas, could be distinguished by correlations with organic matter concentrations and stable isotope fractionation (total organic carbon; TOC, nitrogen, and δ13C. Overall, samples from the AP were higher in nutrient content (TOC, nitrogen, and NH4+ and communities in these samples had higher relative abundances of operational taxonomic units (OTUs classified as the diatom, Chaetoceros, a marine cercozoan and four OTUs classified as Cytophaga or Flavobacteria. As these OTUs were strongly correlated with TOC, the data suggests the diatoms could be a source of organic matter and the Bacteroidetes and cercozoan are grazers that consume the organic matter. Additionally, samples from WA have lower nutrients and were dominated by Thaumarchaeota, which could be related to their known ability to thrive as lithotrophs. This study documents the largest analysis of benthic microbial communities to date in the Southern Ocean, representing almost half the continental shoreline of Antarctica, and documents trophic interactions and coupling of pelagic and benthic communities. Our results indicate potential modifications in carbon sequestration processes related to change in community composition, identifying a

Challenges for understanding Antarctic surface hydrology and ice-shelf stability

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Kingslake, J.; Bell, R. E.; Banwell, A. F.; Boghosian, A.; Spergel, J.; Trusel, L. D.

2017-12-01

It is widely hypothesized that surface meltwater can contribute to ice mass loss in Antarctica through its impact on ice-shelf stability. Meltwater potentially expedites ice-shelf calving by flowing into and enlarging existing crevasses, and could even trigger ice-shelf disintegration via stresses generated by melt ponds. When ice shelves collapse, the adjacent grounded ice accelerates and thins, which contributes to sea-level rise. How these mechanisms mediate the interactions between the atmosphere, the ocean and the ice sheet is the subject of long-standing research efforts. The drainage of water across the surface of the Antarctic Ice Sheet and its ice shelves is beginning to be recognized as another important aspect of the system. Recent studies have revealed that surface meltwater drainage is more widespread than previously thought and that surface hydrological systems in Antarctica may expand and proliferate this century. Contrasting hypotheses regarding the impact of the proliferation of drainage systems on ice-shelf stability have emerged. Surface drainage could deliver meltwater to vulnerable area or export meltwater from ice shelves entirely. Which behavior dominates may have a large impact on the future response of the Antarctic Ice Sheet to atmospheric warming. We will discuss these recent discoveries and hypotheses, as well as new detailed studies of specific areas where hydrological systems are well developed, such as Amery and Nimrod Ice Shelves. We will highlight analogies that can be drawn with Greenlandic (near-)surface hydrology and, crucially, where hydrological systems on the two ice sheets are very different, leading to potentially important gaps in our understanding. Finally, we will look ahead to the key questions that we argue will need to be if we are to determine the role Antarctic surface hydrology could play in the future of the ice sheet. These include: Where does meltwater pond today and how will this change this century? What

Direct observations of the Antarctic Slope Current transport at 113°E

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Peña-Molino, B.; McCartney, M. S.; Rintoul, S. R.

2016-10-01

The Antarctic Slope Current (ASC), defined here as the region of westward flow along the continental slope off Antarctica, forms the southern limb of the subpolar gyres. It regulates the exchange of water across the shelf break and provides a path for interbasin westward transport. Despite its significance, the ASC remains largely unobserved around most of the Antarctic continent. Here we present direct velocity observations from a 17 month current meter moored array deployed across the continental slope between the 1000 and the 4200 m isobaths, in the southeastern Indian Ocean near 113°E. The observed time-mean flow consists of a surface-intensified jet associated with the Antarctic Slope Front (ASF) and a broader bottom-intensified westward flow that extends out to approximately the 4000 m isobath and is strongest along the upper slope. The time-mean transport of the ASC is -29.2 Sv. Fluctuations in the transport are large, typically exceeding the mean by a factor of 2. They are mainly due to changes in the northward extent of the current over the lower slope. However, seasonal changes in the wind also drive variations in the transport of the ASF and the flow in the upper slope. Both mean and variability are largely barotropic, thus invisible to traditional geostrophic methods.

Seasonal variations and vertical features of aerosol particles in the Antarctic troposphere

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Keiichiro Hara

2010-12-01

Full Text Available Tethered balloon-borne aerosol measurements were carried out at Syowa Station, Antarctica during the 46th Japanese Antarctic Research Expedition. CN concentration had a maximum in the summer, whereas the number concentrations of fine particles (D_p>0.3 μm and coarse particles (D_p>2.0 μm increased during the winter-spring. The range of CN concentration was 30-2200 cm^ near the surface (surface-500 m and 7-7250 cm^ in the lower free troposphere (>1500 m. During the austral summer, higher CN concentration was often observed in the lower free troposphere. Frequent appearance of higher CN concentration in the free troposphere relative to the surface measurements strongly suggests that new particle formation in the Antarctic regions occurs in the lower free troposphere. Single particle analysis indicated that most of the aerosol particles during the winter were composed of Mg-enriched sea-salt particles originated from sea-salt fractionation on the sea-ice and their modified particles by NO_3^ and SO_4^. This suggests that sea-salt fractionation on sea-ice and modification of sea-salt particles were affected greatly by aerosol hygroscopicity during the winter. Antarctic haze layer was observed not only in the boundary layer but also in the lower free troposphere.

Expedition to the Antarctic Peninsula in the 2012-2013 campaign with participation of the CIEMAT; Expedicion a la Peninsula Antartica en la campana 2012-2013 con participacion del CIEMAT

Energy Technology Data Exchange (ETDEWEB)

Schmid, T.; Lopez Martinez, J.; Duran Valsero, J. J.; O' Neill, T.

2013-07-01

Antarctica is the most remote, hostile and uninhabited continent on Earth. It is key to understand how our planet works and the impact we have on it. The Antarctic has many unique geological, glaciological and biological features. Its environment and its biological communities have a limited natural capacity for recovery from the alterations they undergo and therefore can be easily and irreversibly damaged. This is why the Antarctic Treaty and, in particular, the Protocol on Environmental Protection of the Antarctic Treaty (the Madrid Protocol) pay special attention to these matters. In this context, the effects of climate change and also the growing pressure of human activities, including scientific research and tourist visits, are reason for this attention. (Author)

Energetic electron precipitation characteristics observed from Antarctica during a flux dropout event

Science.gov (United States)

Clilverd, Mark A.; Cobbett, Neil; Rodger, Craig J.; Brundell, James B.; Denton, Michael H.; Hartley, David P.; Rodriguez, Juan V.; Danskin, Donald; Raita, Tero; Spanswick, Emma L.

2013-11-01

from two autonomous VLF radio receiver systems installed in a remote region of the Antarctic in 2012 is used to take advantage of the juxtaposition of the L = 4.6 contour, and the Hawaii-Halley, Antarctica, great circle path as it passes over thick Antarctic ice shelf. The ice sheet conductivity leads to high sensitivity to changing D region conditions, and the quasi constant L shell highlights outer radiation belt processes. The ground-based instruments observed several energetic electron precipitation events over a moderately active 24 h period, during which the outer radiation belt electron flux declined at most energies and subsequently recovered. Combining the ground-based data with low and geosynchronous orbiting satellite observations on 27 February 2012, different driving mechanisms were observed for three precipitation events with clear signatures in phase space density and electron anisotropy. Comparison between flux measurements made by Polar-orbiting Operational Environmental Satellites (POES) in low Earth orbit and by the Antarctic instrumentation provides evidence of different cases of weak and strong diffusion into the bounce loss cone, helping to understand the physical mechanisms controlling the precipitation of energetic electrons into the atmosphere. Strong diffusion events occurred as the bounce loss cone. Two events had a factor of about 3 to 10 times more >30 keV flux than was reported by POES, more consistent with strong diffusion conditions.

A great earthquake in the Antarctic plate on 25 March 1998

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Yoko Tono

1998-07-01

Full Text Available A great earthquake occurred in the Antarctic Plate at 03h 12m 24.7s (UT on 25 March 1998. The location and magnitude of the earthquake determined by United States Geological Survey are as follows : 62.876°S, 149.712°E, 10km depth m_b 6.8,M_s 8.0. In response to a request for earthquake information from Syowa Station (69°00′S, 39°35′E to Dumont d'Urville Station of France (66°40′S, 140°01′E, the station leader reported that all wintering members in the station felt a quake and something on the shelf in the building fell down. The intensity at the station was estimated to be III∿IV by the intensity scale of Japanese Meteorological Agency. This earthquake is the first great earthquake of magnitude 8 recorded in the Antarctic Plate since IGY of 1957 and the first earthquake felt in Antarctica except for volcanic earthquakes.

Understanding and protecting the world's biodiversity: the role and legacy of the SCAR programme "Evolution and Biodiversity in the Antarctic".

Science.gov (United States)

di Prisco, Guido; Convey, Peter; Gutt, Julian; Cowan, Don; Conlan, Kathleen; Verde, Cinzia

2012-12-01

Current global changes are prompting scientists and governments to consider the risk of extinction of species inhabiting environments influenced by ice. Concerted, multidisciplinary, international programmes aimed at understanding life processes, evolution and adaptations in the Polar Regions will help to counteract such an event by protecting polar life and ecosystems. There is a long tradition of international scientific cooperation in Antarctica that provides a strong foundation for such approaches. While basic understanding is emerging, we still largely lack predictive biological models, and need to achieve further integration amongst biological and non-biological disciplines. The ongoing SCAR Science Research Programme, "Evolution and Biodiversity in the Antarctic (EBA)" has successfully carried out its crucial role of providing an overarching umbrella for SCAR research in Life Sciences. Now is the time for aiming to progress beyond this important role, and the Antarctic biology community is proposing two programmes, focussed on distinct but complementary aspects of polar biology and working across marine, freshwater and terrestrial environments: "State of the Antarctic Ecosystem (AntEco)", and "Antarctic Thresholds--Ecosystem Resilience and Adaptation (AnT-ERA)". These programmes are the legacy of EBA, and they are key to understanding and protect Antarctic biodiversity. Copyright © 2012 Elsevier B.V. All rights reserved.

Exploration of Gamburtsev Subglacial Mountains, East Antarctica: Background and Plans for the Near Future

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Talalay, Pavel; Sun, Youhong; Zhao, Yue; Li, Yuansheng; Cao, Pinlu; Xu, Huiwen; Zheng, Zhichuan; Wang, Rusheng; Zhang, Nan; Markov, Alexey; Yu, Dahui; Fan, Xiaopeng; Hu, Zhengyi; Yang, Cheng; Gong, Da; Hong, Jialing; Liu, Chunpeng; Han, Junjie; Yu, Chengfeng; Wang, Lili

2014-05-01

The Gamburtsev Subglacial Mountains (GSM), located in the central part of East Antarctica, were discovered by the Soviet team of the 3rd Complex Antarctic Expedition in 1958-1959. The GSM has highly dissected Alpine topography reaching maximum elevations of 3000 m and are completely covered by over 600 m of ice and snow. The mechanism driving uplift of the young-shaped GSM in the middle of the old East Antarctic Shield is unknown. With only limited constraints available on the topography, geology, and lithospheric structure, the origin of the GSM has been a matter of considerable speculation. The latest interpretation suggested that the GSM were formed during Permian and Cretaceous (roughly 250-100 Ma ago) due to the combination of rift-flank uplift, root buoyancy and the isostatic response. Later on, the Antarctic Ice Sheet covered the range and protected it from erosion. However, this theory cannot explain lack of erosion process during many millions years in between uplifting and beginning of glaciation. The next step of the GSM exploration focuses on the direct observation of ice sheet bed by drilling. In order to penetrate into subglacial bedrock in the GSM region the development activity already has been started in China. Drilling operations in Antarctica are complicated by extremely low temperature at the surface and within ice sheet, by ice flow, the absence of roads and infrastructures, storms, winds, snowfalls, etc. All that are the reasons that up to the present moment bedrock cores were never obtained at inland of Antarctica. It is proposed to use cable-suspended drilling technology in which an armored cable with a winch is used instead of a pipe-string to provide power to the down-hole motor system and to retrieve the down-hole unit. It is assumed to choose the drill site with the ice thickness at most of 1000 m and to pierce into the mountain slope to a depth of few meters. Proposed borehole construction includes five following steps: (1) dry core

Spatially Extensive Standardized Surveys Reveal Widespread, Multi-Decadal Increase in East Antarctic Adélie Penguin Populations.

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Southwell, Colin; Emmerson, Louise; McKinlay, John; Newbery, Kym; Takahashi, Akinori; Kato, Akiko; Barbraud, Christophe; DeLord, Karine; Weimerskirch, Henri

2015-01-01

Seabirds are considered to be useful and practical indicators of the state of marine ecosystems because they integrate across changes in the lower trophic levels and the physical environment. Signals from this key group of species can indicate broad scale impacts or response to environmental change. Recent studies of penguin populations, the most commonly abundant Antarctic seabirds in the west Antarctic Peninsula and western Ross Sea, have demonstrated that physical changes in Antarctic marine environments have profound effects on biota at high trophic levels. Large populations of the circumpolar-breeding Adélie penguin occur in East Antarctica, but direct, standardized population data across much of this vast coastline have been more limited than in other Antarctic regions. We combine extensive new population survey data, new population estimation methods, and re-interpreted historical survey data to assess decadal-scale change in East Antarctic Adélie penguin breeding populations. We show that, in contrast to the west Antarctic Peninsula and western Ross Sea where breeding populations have decreased or shown variable trends over the last 30 years, East Antarctic regional populations have almost doubled in abundance since the 1980's and have been increasing since the earliest counts in the 1960's. The population changes are associated with five-year lagged changes in the physical environment, suggesting that the changing environment impacts primarily on the pre-breeding age classes. East Antarctic marine ecosystems have been subject to a number of changes over the last 50 years which may have influenced Adélie penguin population growth, including decadal-scale climate variation, an inferred mid-20th century sea-ice contraction, and early-to-mid 20th century exploitation of fish and whale populations.

Spatially Extensive Standardized Surveys Reveal Widespread, Multi-Decadal Increase in East Antarctic Adélie Penguin Populations.

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Colin Southwell

Full Text Available Seabirds are considered to be useful and practical indicators of the state of marine ecosystems because they integrate across changes in the lower trophic levels and the physical environment. Signals from this key group of species can indicate broad scale impacts or response to environmental change. Recent studies of penguin populations, the most commonly abundant Antarctic seabirds in the west Antarctic Peninsula and western Ross Sea, have demonstrated that physical changes in Antarctic marine environments have profound effects on biota at high trophic levels. Large populations of the circumpolar-breeding Adélie penguin occur in East Antarctica, but direct, standardized population data across much of this vast coastline have been more limited than in other Antarctic regions. We combine extensive new population survey data, new population estimation methods, and re-interpreted historical survey data to assess decadal-scale change in East Antarctic Adélie penguin breeding populations. We show that, in contrast to the west Antarctic Peninsula and western Ross Sea where breeding populations have decreased or shown variable trends over the last 30 years, East Antarctic regional populations have almost doubled in abundance since the 1980's and have been increasing since the earliest counts in the 1960's. The population changes are associated with five-year lagged changes in the physical environment, suggesting that the changing environment impacts primarily on the pre-breeding age classes. East Antarctic marine ecosystems have been subject to a number of changes over the last 50 years which may have influenced Adélie penguin population growth, including decadal-scale climate variation, an inferred mid-20th century sea-ice contraction, and early-to-mid 20th century exploitation of fish and whale populations.

Observations of atmospheric lead-210 over the Atlantic Ocean and Antarctica during the FINNARP-1999/2999 Expedition

International Nuclear Information System (INIS)

Paatero, J.; Virkkula, A.; Hillamo, R.; Koponen, I.

2002-01-01

Physical and chemical properties of the atmosphere were measured in November-December 1999 onboard the Russian research vessel Akademik Fedorov over the Atlantic Ocean between the English Channel and the coast of Antarctica. After the cruise the measurements were continued in January 2000 at the Finnish research station Aboa (73 deg. 03'S, 13 deg. 25'W, 470 m above sea level) in Dronning Maud Land, Antarctica. The location of the station is about 170 km inland from the coast of Weddell Sea. The study is part of the Finnish Antarctic Research Programme (FINNARP) financed by the Academy of Finland. The observed 210 Pb activity concentrations in the air varied between 24 and 790 μBq/m 3 during the cruise between the English Channel and Cape town. The highest values were recorded close ( 210 Pb activity concentrations varied between 3 . At the research station Aboa the observed values varied between 3 . Between 6 and 11 January 2000 the air masses at Aboa originated from central regions of Antarctica according to the trajectory calculations made with the NORA Hysplit model. The concentrations were below detection limit between 11 and 14 January. These samples were connected to the air masses originating from the South Atlantic Ocean. Between 14 and 20 January air masses came to Aboa mainly from easterly direction from coastal and inland regions of the Antarctica. (LN)

Antarctic Mass Loss from GRACE from Space- and Time-Resolved Modeling with Slepian Functions

Science.gov (United States)

Simons, F. J.; Harig, C.

2013-12-01

The melting of polar ice sheets is a major contributor to global sea-level rise. Antarctica is of particular interest since most of the mass loss has occurred in West Antarctica, however updated glacial isostatic adjustment (GIA) models and recent mass gains in East Antarctica have reduced the continent-wide integrated decadal trend of mass loss. Here we present a spatially and temporally resolved estimation of the Antarctic ice mass change using Slepian localization functions. With a Slepian basis specifically for Antarctica, the basis functions maximize their energy on the continent and we can project the geopotential fields into a sparse set of orthogonal coefficients. By fitting polynomial functions to the limited basis coefficients we maximize signal-to-noise levels and need not perform smoothing or destriping filters common to other approaches. In addition we determine an empirical noise covariance matrix from the GRACE data to estimate the uncertainty of mass estimation. When applied to large ice sheets, as in our own recent Greenland work, this technique is able to resolve both the overall continental integrated mass trend, as well as the spatial distribution of the mass changes over time. Using CSR-RL05 GRACE data between Jan. 2003 and Jan 2013, we estimate the regional accelerations in mass change for several sub-regions and examine how the spatial pattern of mass has changed. The Amundsen Sea coast of West Antarctica has experienced a large acceleration in mass loss (-26 Gt/yr^2). While mass loss is concentrated near Pine Island and Thwaites glaciers, it has also increased along the coast further towards the Ross ice shelf.

Impact of Antarctic mixed-phase clouds on climate.

Science.gov (United States)

Lawson, R Paul; Gettelman, Andrew

2014-12-23

Precious little is known about the composition of low-level clouds over the Antarctic Plateau and their effect on climate. In situ measurements at the South Pole using a unique tethered balloon system and ground-based lidar reveal a much higher than anticipated incidence of low-level, mixed-phase clouds (i.e., consisting of supercooled liquid water drops and ice crystals). The high incidence of mixed-phase clouds is currently poorly represented in global climate models (GCMs). As a result, the effects that mixed-phase clouds have on climate predictions are highly uncertain. We modify the National Center for Atmospheric Research (NCAR) Community Earth System Model (CESM) GCM to align with the new observations and evaluate the radiative effects on a continental scale. The net cloud radiative effects (CREs) over Antarctica are increased by +7.4 Wm(-2), and although this is a significant change, a much larger effect occurs when the modified model physics are extended beyond the Antarctic continent. The simulations show significant net CRE over the Southern Ocean storm tracks, where recent measurements also indicate substantial regions of supercooled liquid. These sensitivity tests confirm that Southern Ocean CREs are strongly sensitive to mixed-phase clouds colder than -20 °C.

Lipids and pigment-protein complexes of photosynthetic apparatus of Deschampsia antarctica Desv. plants under UV-B radiation

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Svietlova N. B.

2012-01-01

Full Text Available Aim. To investigate structural and functional modifications of major components of photosynthetic membranes of endemic antarctic species D. antarctica under UV-B radiation. Methods. For quantitative determination of photosynthetic membrane components we used Arnon’s method (for chlorophylls and carotenoids; separation of carotenoids was carried out by Merzlyak’s method; polar lipids were isolated by Zill and Harmon method in modification of Yakovenko and Mihno; glycolipids separation and identification we carried out by Yamamoto method; and sulfoquinovosyl diacylglycerol content was determined by Kean method. The separation, disintegration and determination of pigment-protein complexes of chloroplasts were carried out by Anderson method. Authenticity of differences between the mean arithmetic values of indices was set after the Student criterion. Differences were considered as reliable at p 0.05. Results. We determined structural and functional changes in lipids, carotenoids and pigment-protein complexes at the photosyntetic apparatus level in D. antarctica plants under UV-B radiation. Conclusions. Adaptation of D. antarctica plants to UV-B radiation is accompanied by a cascade of physiological and biochemical rearrangements at the level of photosynthetic apparatus, manifested as the changes in pigment, lipid and pigment-protein complexes content

Persistent organochlorines in high-Antarctic fish; Persistente chlororganische Verbindungen in hochantarktischen Fischen

Energy Technology Data Exchange (ETDEWEB)

Zimmermann, S.

1997-11-01

24 chlorinated hydrocarbons from different classes (PCB, HCH, DDT, Chlordane, Hexachlorobenzene and Octachlorostyrene) were analyzed in four species of high-Antarctic fish (Aethotaxis mitopteryx, Pleuragramma antarcticum, Trematomus lepidorhinus, and Chinodraco myersi). The concentrations were in the order of 1 {mu}g/kg wet weight or 10 {mu}g/kg lipid weight, respectively. Highest concentrations were measured for HCB in all species. The species showed different distribution patterns for the organochlorines studied. Compared with concentrations in fish from other regions the organochlorine levels measured in Antarctic fish are rather low. It is unlikely that the burden of organochlorines will cause any toxic effects in high-Antarctic fish yet. Nevertheless, with regard to the sensitive Antarctic ecosystem, even small concentrations carry a high risk of harm for Antarctic life. Environmental pollution in Antarctica should be observed with a monitoring program using standardized methods. For this purpose, the fish species studied are very useful as bioindicators for organochlorine contamination. (orig.) [Deutsch] 24 persistente Chlorkohlenwasserstoffe verschiedener Schadstoffgruppen (PCB, HCH, DDT, Chlordan, Hexachlorbenzol und Octachlorstyrol) wurden in vier hochantarktischen Fischarten (Aethotaxis mitopteryx, Pleuragramma antarcticum, Trematomus lepidorhinus und Chionodraco myersi). Die Konzentrationen der nachgewiesenen Schadstoffe im Ganzfisch liegen jeweils in der Groessenordnung von 1 {mu}g/kg Feuchtgewicht bzw. 10 {mu}g/kg Lipidgewicht mit erheblichen Schwankungen je nach Schadstoff und Art. Die Spezies zeigen artspezifische Schadstoffverteilungsmuster. Die Konzentrationen sind gegenueber denen in Fischen aus Gebieten mit staerkerem zivilisatorischem Einfluss eher niedrig. Die Fremstoffbelastungen der hochantarktischen Fische fuehren wahrscheinlich noch nicht zu messbaren toxischen Effekten bei den Fischen. Dennoch geht von den Schadstoffen in Hinblick auf das

Antifouling activity in some benthic Antarctic invertebrates by "in situ" experiments at Deception Island, Antarctica.

Science.gov (United States)

Angulo-Preckler, Carlos; Cid, Cristina; Oliva, Francesc; Avila, Conxita

2015-04-01

Competition for space is a remarkable ecological force, comparable to predation, producing a strong selective pressure on benthic invertebrates. Some invertebrates, thus, possess antimicrobial compounds to reduce surface bacterial growth. Antimicrobial inhibition is the first step in avoiding being overgrown by other organisms, which may have a negative impact in feeding, respiration, reproduction … The in situ inhibition of bacterial biofilm was used here as an indicator of antifouling activity by testing hydrophilic extracts of twelve Antarctic invertebrates. Using two different approaches (genetics and confocal techniques) different levels of activity were found in the tested organisms. In fact, differences within body parts of the studied organisms were determined, in agreement with the Optimal Defense Theory. Eight out of 15 extracts tested had negative effects on fouling after 28 days submerged in Antarctic waters. Thus, although chemical defenses may be quite species-specific in their ecological roles, these results suggest that different chemical strategies exist to deal with space competition. Copyright © 2015 Elsevier Ltd. All rights reserved.

Regional geology mapping using satellite-based remote sensing approach in Northern Victoria Land, Antarctica

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Pour, Amin Beiranvand; Park, Yongcheol; Park, Tae-Yoon S.; Hong, Jong Kuk; Hashim, Mazlan; Woo, Jusun; Ayoobi, Iman

2018-06-01

Satellite remote sensing imagery is especially useful for geological investigations in Antarctica because of its remoteness and extreme environmental conditions that constrain direct geological survey. The highest percentage of exposed rocks and soils in Antarctica occurs in Northern Victoria Land (NVL). Exposed Rocks in NVL were part of the paleo-Pacific margin of East Gondwana during the Paleozoic time. This investigation provides a satellite-based remote sensing approach for regional geological mapping in the NVL, Antarctica. Landsat-8 and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) datasets were used to extract lithological-structural and mineralogical information. Several spectral-band ratio indices were developed using Landsat-8 and ASTER bands and proposed for Antarctic environments to map spectral signatures of snow/ice, iron oxide/hydroxide minerals, Al-OH-bearing and Fe, Mg-OH and CO3 mineral zones, and quartz-rich felsic and mafic-to-ultramafic lithological units. The spectral-band ratio indices were tested and implemented to Level 1 terrain-corrected (L1T) products of Landsat-8 and ASTER datasets covering the NVL. The surface distribution of the mineral assemblages was mapped using the spectral-band ratio indices and verified by geological expeditions and laboratory analysis. Resultant image maps derived from spectral-band ratio indices that developed in this study are fairly accurate and correspond well with existing geological maps of the NVL. The spectral-band ratio indices developed in this study are especially useful for geological investigations in inaccessible locations and poorly exposed lithological units in Antarctica environments.

Influence of Meteorological Regimes on Cloud Microphysics Over Ross Island, Antarctica

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Glennon, C.; Wang, S. H.; Scott, R. C.; Bromwich, D. H.; Lubin, D.

2017-12-01

The Antarctic provides a sharp contrast in cloud microphysics from the high Arctic, due to orographic lifting and resulting strong vertical motions induced by mountain ranges and other varying terrain on several spatial scales. The Atmospheric Radiation Measurement (ARM) West Antarctic Radiation Experiment (AWARE) deployed advanced cloud remote sensing equipment to Ross Island, Antarctica, from December 2015 until January 2016. This equipment included scanning and zenith radars operating in the Ka and X bands, a high spectral resolution lidar (HSRL), and a polarized micropulse lidar (MPL). A major AWARE objective is to provide state-of-the-art data for improving cloud microphysical parameterizations in climate models. To further this objective we have organized and classified the local Ross Island meteorology into distinct regimes using k-means clustering on ERA-Interim reanalysis data. We identify synoptic categories producing unique regimes of cloud cover and cloud microphysical properties over Ross Island. Each day of observations can then be associated with a specific meteorological regime, thus assisting modelers with identifying case studies. High-resolution (1 km) weather forecasts from the Antarctic Mesoscale Prediction System (AMPS) are sorted into these categories. AMPS-simulated anomalies of cloud fraction, near-surface air temperature, and vertical velocity at 500-mb are composited and compared with ground-based radar and lidar-derived cloud properties to identify mesoscale meteorological processes driving Antarctic cloud formation. Synoptic lows over the Ross and Amundsen Seas drive anomalously warm conditions at Ross Island by injecting marine air masses inland over the West Antarctic Ice Sheet (WAIS). This results in ice and mixed-phase orographic cloud systems arriving at Ross Island from the south to southeast along the Transantarctic Mountains. In contrast, blocking over the Amundsen Sea region brings classical liquid-dominated mixed-phase and

Variations of the Antarctic Circumpolar Current (ACC) in the Kerguelen Sector during the Last Deglaciation : sedimentological and geochemical evidences

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Bout-Roumazeilles, V.; Beny, F.; Mazaud, A.; Michel, E.; Crosta, X.; Davies, G. R.; Bory, A. J. M.

2017-12-01

High-resolution sedimentological and geochemical records were obtained from two sediment cores recovered by the French R/V Marion Dufresne during the INDIEN-SUD-ACC cruises near the sub-Antarctic Kerguelen Islands (49°S). This area is ideal to record past oceanic and atmospheric changes in the Southern Ocean because they are currently located in the northern branch of the Antarctic Circumpolar Current and under the direct influence of Southern Hemisphere Westerly wind belt. This study focuses on the last termination, with specific emphasis on the impact of severe climatic events (Heinrich Stadial 1, Antarctic Cold Reversal, Younger Dryas) onto the ocean-atmospheric exchange. Results indicates that most of the sediment is derived from the Kerguelen Plateau, characterized by high smectite content. Periodically, a minor contribution of Antarctica is noticeable. In particular, illite variations suggest fast and short northward incursions of Antarctic Bottom Water, probably formed in the Prydz Bay during the last glaciation. Grainsize repartition combined to magnetic parameters show a southward migration of the ACC and the fronts associated from the beginning of the deglaciation, which is consistent with Southern Hemisphere climate variations. On the opposite, it highlights an asynchronous decrease of the ACC strength, with a large drop during the Antarctic Cold Reversal when atmospheric CO2 increase was slowed down. Thus, at least in the studied area, the ACC strength and the Antarctic Climate were not synchronous during the last deglaciation.

The Effects of Interactive Stratospheric Chemistry on Antarctic and Southern Ocean Climate Change in an AOGCM

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Li, Feng; Newman, Paul; Pawson, Steven; Waugh, Darryn

2014-01-01

Stratospheric ozone depletion has played a dominant role in driving Antarctic climate change in the last decades. In order to capture the stratospheric ozone forcing, many coupled atmosphere-ocean general circulation models (AOGCMs) prescribe the Antarctic ozone hole using monthly and zonally averaged ozone field. However, the prescribed ozone hole has a high ozone bias and lacks zonal asymmetry. The impacts of these biases on model simulations, particularly on Southern Ocean and the Antarctic sea ice, are not well understood. The purpose of this study is to determine the effects of using interactive stratospheric chemistry instead of prescribed ozone on Antarctic and Southern Ocean climate change in an AOGCM. We compare two sets of ensemble simulations for the 1960-2010 period using different versions of the Goddard Earth Observing System 5 - AOGCM: one with interactive stratospheric chemistry, and the other with prescribed monthly and zonally averaged ozone and 6 other stratospheric radiative species calculated from the interactive chemistry simulations. Consistent with previous studies using prescribed sea surface temperatures and sea ice concentrations, the interactive chemistry runs simulate a deeper Antarctic ozone hole and consistently larger changes in surface pressure and winds than the prescribed ozone runs. The use of a coupled atmosphere-ocean model in this study enables us to determine the impact of these surface changes on Southern Ocean circulation and Antarctic sea ice. The larger surface wind trends in the interactive chemistry case lead to larger Southern Ocean circulation trends with stronger changes in northerly and westerly surface flow near the Antarctica continent and stronger upwelling near 60S. Using interactive chemistry also simulates a larger decrease of sea ice concentrations. Our results highlight the importance of using interactive chemistry in order to correctly capture the influences of stratospheric ozone depletion on climate

Neumayer III and Kohnen Station in Antarctica operated by the Alfred Wegener Institute

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Christine Wesche

2016-08-01

Full Text Available The Alfred Wegener Institute operates two stations in Dronning Maud Land, Antarctica. The German overwintering station Neumayer III is located on the Ekström Ice Shelf at 70°40’S and 08°16’W and is the logistics base for three long-term observatories (meteorology, air chemistry and geophysics and nearby research activities. Due to the vicinity to the coast (ca. 20 km from the ice shelf edge, the Neumayer III Station is the junction for many German Antarctic expeditions, especially as the starting point for the supply traverse for the second German station Kohnen. The summer station Kohnen is located about 600 km from the coast and 750 km from Neumayer III Station on the Antarctic plateau at 75°S and 00°04’E. It was erected as the base for the deep-drilling ice core project, which took place between 2001 and 2006. Since then Kohnen Station is used as a logistics base for different research projects.

Ice core evidence for secular variability and 200-year dipolar oscillations in atmospheric circulation over East Antarctica during the Holocene

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Delmonte, B. [Laboratoire de Glaciologie et de Geophysique de l' Environnement (LGGE-CNRS), Saint Martin d' Heres (France); Department of Environmental Sciences, University Milano-Bicocca (Italy); Department of Geological Sciences, University of Siena (Italy); Petit, J.R.; Krinner, G. [Laboratoire de Glaciologie et de Geophysique de l' Environnement (LGGE-CNRS), Saint Martin d' Heres (France); Maggi, V. [Department of Environmental Sciences, University Milano-Bicocca (Italy); Jouzel, J. [Laboratoire des Sciences du Climat et de l' Environnement, UMR CEA-CNRS, Saclay (France); Udisti, R. [Chemistry Department, University of Florence (Italy)

2005-05-01

Two Holocene ice core records from East Antarctica (Vostok and EPICA-Dome C) were analysed for dust concentration and size distribution at a temporal resolution of 1 sample per {proportional_to}50 years. A series of volcanic markers randomly distributed over the common part of the ice cores (from 9.8 to 3.5 kyear BP) ensures accurate relative dating ({+-}33 years). Dust-size records from the two sites display oscillations structured in cycles with sub-millennial and secular scale frequencies that are apparently asynchronous. The power spectra of the composite sum ({sigma}) of the two dust-size records display spectral energy mostly for 150- to 500-year periodicities. On the other hand, the 200-year band is common to both records and the 200 year components of the two sites are out-of-phase (100-year lead or lag) over {proportional_to}5.5 kyear, a phenomenon also reflected by a significant (>99% conf. lev.) band in the power spectra of the composite difference ({delta}) of the two size records. During long-range transport, mineral dust originating from the Southern Hemisphere continents is graded to a variable extent depending on the altitude and duration of atmospheric transport. Relatively coarse dust is associated with air mass penetration from the middle-lower troposphere and conversely relatively fine dust with upper troposphere air masses or the influence of subsidence over the Antarctic plateau, a hypothesis already proposed for the changes that occurred during the Last Glacial Maximum to Holocene transition (Delmonte et al. 2004b). Moreover, we assume that the overall fluctuation of air mass advection over Antarctica depends on the meridional pressure gradient with respect to low latitudes, i.e. the Antarctic Oscillation (AAO). We therefore suggest a regional variability in atmospheric circulation over East Antarctica. The 150-500 year power spectrum of the composite ({sigma}) parameter represents the long term variability of the AAO, imprinted by secular

A comparison of the present and last interglacial periods in six Antarctic ice cores

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V. Masson-Delmotte

2011-04-01

Full Text Available We compare the present and last interglacial periods as recorded in Antarctic water stable isotope records now available at various temporal resolutions from six East Antarctic ice cores: Vostok, Taylor Dome, EPICA Dome C (EDC, EPICA Dronning Maud Land (EDML, Dome Fuji and the recent TALDICE ice core from Talos Dome. We first review the different modern site characteristics in terms of ice flow, meteorological conditions, precipitation intermittency and moisture origin, as depicted by meteorological data, atmospheric reanalyses and Lagrangian moisture source diagnostics. These different factors can indeed alter the relationships between temperature and water stable isotopes. Using five records with sufficient resolution on the EDC3 age scale, common features are quantified through principal component analyses. Consistent with instrumental records and atmospheric model results, the ice core data depict rather coherent and homogenous patterns in East Antarctica during the last two interglacials. Across the East Antarctic plateau, regional differences, with respect to the common East Antarctic signal, appear to have similar patterns during the current and last interglacials. We identify two abrupt shifts in isotopic records during the glacial inception at TALDICE and EDML, likely caused by regional sea ice expansion. These regional differences are discussed in terms of moisture origin and in terms of past changes in local elevation histories, which are compared to ice sheet model results. Our results suggest that elevation changes may contribute significantly to inter-site differences. These elevation changes may be underestimated by current ice sheet models.

Multi-decadal survival of an Antarctic nematode, Plectus murrayi, in a -20°C stored moss sample.

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Kagoshima, H; Kito, K; Aizu, T; Shin-i, T; Kanda, H; Kobayashi, S; Toyoda, A; Fujiyama, A; Kohara, Y; Convey, P; Niki, H

2012-01-01

It is not clear for how long Antarctic soil nematodes might tolerate freezing. Samples of the Antarctic moss, Bryum argenteum, were collected on 1 October 1983 at Langhovde, Soya coast, eastern Antarctica and were stored at -20°C. After 25.5 years of storage, living nematodes were recovered from the samples and were identified as Plectus murrayi by morphological examination and nucleotide sequencing of ribosomal RNA loci. The nematodes can grow and reproduce in a water agar plate with bacteria (mainly Pseudomonas sp.) cultured from the moss extract. They showed freezing tolerance at -20°C and -80°C and their survival rate after exposure to -20°C, but not -80°C, was increased if they were initially frozen slowly at a high sub-zero temperature. They also showed some ability to tolerate desiccation stress.

Cosmic and solar gamma-ray x-ray and particle measurements from high altitude balloons in Antarctica

International Nuclear Information System (INIS)

Lin, R.P.

1990-01-01

For measurements of cosmic and solar gamma-rays, hard X-rays, and particles, Antarctica offers the potential for very long, 10--20 day, continuous, twenty-four-hour-a-day observations, with balloon flights circling the South Pole during austral summer. For X-ray/gamma-ray sources at high south latitude the overlying atmosphere is minimized, and for cosmic ray measurements the low geomagnetic cutoff permits entry of low rigidity particles. The first Antarctic flight of a heavy (∼2400 lb.) payload on a large (11.6x10 6 cu. ft.) balloon took place in January, 1988, to search for the gamma-ray lines of 56 Co produced in the new supernova SN 1987A in the Large Magellanic Cloud. The long duration balloon flights presently planned from Antarctica include those for further gamma-ray/hard X-ray studies of SN 1987A and for the NASA Max '91 program for solar flare studies

Assessment of Antarctic moss health from multi-sensor UAS imagery with Random Forest Modelling

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Turner, Darren; Lucieer, Arko; Malenovský, Zbyněk; King, Diana; Robinson, Sharon A.

2018-06-01

Moss beds are one of very few terrestrial vegetation types that can be found on the Antarctic continent and as such mapping their extent and monitoring their health is important to environmental managers. Across Antarctica, moss beds are experiencing changes in health as their environment changes. As Antarctic moss beds are spatially fragmented with relatively small extent they require very high resolution remotely sensed imagery to monitor their distribution and dynamics. This study demonstrates that multi-sensor imagery collected by an Unmanned Aircraft System (UAS) provides a novel data source for assessment of moss health. In this study, we train a Random Forest Regression Model (RFM) with long-term field quadrats at a study site in the Windmill Islands, East Antarctica and apply it to UAS RGB and 6-band multispectral imagery, derived vegetation indices, 3D topographic data, and thermal imagery to predict moss health. Our results suggest that moss health, expressed as a percentage between 0 and 100% healthy, can be estimated with a root mean squared error (RMSE) between 7 and 12%. The RFM also quantifies the importance of input variables for moss health estimation showing the multispectral sensor data was important for accurate health prediction, such information being essential for planning future field investigations. The RFM was applied to the entire moss bed, providing an extrapolation of the health assessment across a larger spatial area. With further validation the resulting maps could be used for change detection of moss health across multiple sites and seasons.

Using visible reflectance spectroscopy to reconstruct historical changes in chlorophyll a concentration in East Antarctic ponds

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Qianqian Chen

2013-12-01

Full Text Available The visible reflectance spectroscopy (VRS and chlorophyll a concentration were determined in three sediment profiles collected from East Antarctica to investigate the potential application of VRS in reconstructing historical changes in Antarctic lake primary productivity. The results showed that the appearance of a trough at 650–700 nm is an important marker for chlorophyll a concentration and can therefore be used to distinguish the sedimentary organic matter source from guano and algae. The measured chlorophyll a content had significant positive correlations with the trough area between 650 and 700 nm, and no distinct trough was found in the sediments with organic matter completely derived from guano. Modelling results showed that the spectra spectrally inferred chlorophyll a content, and the measured data exhibit consistent trends with depth, showing that the dimensionless trough area can serve as an independent proxy for reconstructing historical fluctuations in the primary production of Antarctic ponds. The correlation of phosphorus (P with measured and inferred chlorophyll a contents in ornithogenic sediments near penguin colonies indicates that the change in primary productivity in the Antarctic ponds investigated was closely related to the amount of guano input from these birds.

Site-Specific Variability in the Chemical Diversity of the Antarctic Red Alga Plocamium cartilagineum

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Ryan M. Young

2013-06-01

Full Text Available Plocamium cartilagineum is a common red alga on the benthos of Antarctica and can be a dominant understory species along the western Antarctic Peninsula. Algae from this region have been studied chemically, and like “P. cartilagineum” from other worldwide locations where it is common, it is rich in halogenated monoterpenes, some of which have been implicated as feeding deterrents toward sympatric algal predators. Secondary metabolites are highly variable in this alga, both qualitatively and quantitatively, leading us to probe individual plants to track the possible link of variability to genetic or other factors. Using cox1 and rbcL gene sequencing, we find that the Antarctic alga divides into two closely related phylogroups, but not species, each of which is further divided into one of five chemogroups. The chemogroups themselves, defined on the basis of Bray-Curtis similarity profiling of GC/QqQ chromatographic analyses, are largely site specific within a 10 km2 area. Thus, on the limited geographical range of this analysis, P. cartilagineum displays only modest genetic radiation, but its secondary metabolome was found to have experienced more extensive radiation. Such metabogenomic divergence demonstrated on the larger geographical scale of the Antarctic Peninsula, or perhaps even continent-wide, may contribute to the discovery of cryptic speciation.

Regionally Optimized GRACE Processing and Inter-comparison on the Antarctic Ice Sheet

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Mohajerani, Y.; Velicogna, I.; Sutterley, T. C.; Rignot, E. J.

2017-12-01

The Antarctic ice sheet is losing mass at an accelerating rate, with a sea level contribution that changed from 0.08mm/yr from 1992 to 2001 to 0.4mm/yr from 2002 to 2011. While most of this contribution comes from West Antarctica, Totten Glacier has the largest discharge of ice in East Antarctica, with a sea level rise potential of 3.9 m. Furthermore, the drainage basin of Totten Glacier, along the neighboring Moscow University Glacier are below sea level, extending hundreds of kilometers inland. Therefore, obtaining regional estimates of both western and eastern Antarctic basins are of critical importance. The GRACE (Gravity Recovery and Climate Experiment) satellite has been providing mass balance time-series from geoid changes since 2002. Several mascon and harmonic GRACE solutions are available from different processing centers. Here, we evaluate the various solutions across the ice sheet and a new set of regionally optimized mascons to study the mass balance of Totten and Moscow University glaciers. We obtain a trend of -16.5±4.1Gt/yr with an acceleration of -2.0±1.8Gt/yr2 for the two glaciers for the period April 2002 to December 2016 using the Ivins et al (2013) GIA model (errors include leakage, GIA, and regression errors). We compare the results with the Mass Budget Method that combines ice discharge (D) and surface mass balance (SMB) from two models: 1) RACMO2.3, and 2) MAR3.6.4. MBM/RACMO2.3 shows the best agreement with the GRACE estimates. Within the common period from April 2002 to December 2015, the MBM/RACMO2.3 and MAR3.6.4 results are -15.6±1.8Gt/yr and -6.7±1.5Gt/yr respectively, while the GRACE time-series has a trend of -14.8±2.7 Gt/yr. We extend the study to the Getz Ice Shelf, the third largest ice shelf in West Antarctica after Ronne and Ross West ice shelves. We compare our gravity-derived mass estimates, the mass budget estimates, and the volume changes from altimetry data to compare the estimates and obtain a multi-sensor assessment

Elemental composition of Usnea sp lichen from Potter Peninsula, 25 de Mayo (King George) Island, Antarctica

International Nuclear Information System (INIS)

Bubach, Débora; Catán, Soledad Perez; Di Fonzo, Carla; Dopchiz, Laura

2016-01-01

Several pollutants, which include metals, are present in the Antarctic atmosphere, snow, marine and terrestrial organisms. This work reports the elements incorporated by Usnea sp thalli in Potter Peninsula, 25 de Mayo (King George) Island, South Shetlands, Antarctica. Geological origin was analyzed as possible sources of elements. For this purpose, correlations were done using a geochemical tracer, principal component analysis and enrichment factors were computed. Lithophile elements from particulate matter were present in most of the sampling sites. Bromine, Se and Hg showed the highest enrichment factors suggesting other sources than the particulate matter. Mercury values found in Usnea sp were in the same range as those reported for Deception Island (South Shetlands) and remote areas from the Patagonia Andes. - Highlights: • Hg enrichment factor was higher in ASPA than in human settlements area. • The elemental composition in Usnea sp from Antarctica reflected the human influence. • Bromine, Ca, Sr, Se, Fe, Hg and K contents indicated origins natural and anthropic. • The data will be considered as baselines for Potter Peninsula, King George Island. - This study provides recent element contents in Usnea sp from Potter Peninsula, South Shetland Islands, Antarctica. Some of them are the first concentration reported by Argentina.

A first approach to calculate BIOCLIM variables and climate zones for Antarctica

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Wagner, Monika; Trutschnig, Wolfgang; Bathke, Arne C.; Ruprecht, Ulrike

2018-02-01

For testing the hypothesis that macroclimatological factors determine the occurrence, biodiversity, and species specificity of both symbiotic partners of Antarctic lecideoid lichens, we present a first approach for the computation of the full set of 19 BIOCLIM variables, as available at http://www.worldclim.org/ for all regions of the world with exception of Antarctica. Annual mean temperature (Bio 1) and annual precipitation (Bio 12) were chosen to define climate zones of the Antarctic continent and adjacent islands as required for ecological niche modeling (ENM). The zones are based on data for the years 2009-2015 which was obtained from the Antarctic Mesoscale Prediction System (AMPS) database of the Ohio State University. For both temperature and precipitation, two separate zonings were specified; temperature values were divided into 12 zones (named 1 to 12) and precipitation values into five (named A to E). By combining these two partitions, we defined climate zonings where each geographical point can be uniquely assigned to exactly one zone, which allows an immediate explicit interpretation. The soundness of the newly calculated climate zones was tested by comparison with already published data, which used only three zones defined on climate information from the literature. The newly defined climate zones result in a more precise assignment of species distribution to the single habitats. This study provides the basis for a more detailed continental-wide ENM using a comprehensive dataset of lichen specimens which are located within 21 different climate regions.

What Controls the Size of the Antarctic Ozone Hole?

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Bhartia, P. K. (Technical Monitor); Newman, Paul A.; Kawa, S. Randolph; Nash, Eric R.

2002-01-01

The Antarctic ozone hole is a region of extremely large ozone depletion that is roughly centered over the South Pole. Since 1979, the area coverage of the ozone hole has grown from near zero size to over 24 Million square kilometers. In the 8-year period from 1981 to 1989, the area expanded by 18 Million square kilometers. During the last 5 years, the hole has been observed to exceed 25 Million square kilometers over brief periods. We will review these size observations, the size trends, and the interannual variability of the size. The area is derived from the area enclosed by the 220 DU total ozone contour. We will discuss the rationale for the choice of 220 DU: 1) it is located near the steep gradient between southern mid-latitudes and the polar region, and 2) 220 DU is a value that is lower than the pre- 1979 ozone observations over Antarctica during the spring period. The phenomenal growth of the ozone hole was directly caused by the increases of chlorine and bromine compounds in the stratosphere. In this talk, we will show the relationship of the ozone hole's size to the interannual variability of Antarctic spring temperatures. In addition, we will show the relationship of these same temperatures to planetary-scale wave forcings.

Variations of snow accumulation rate in Central Antarctica over the last 250 years

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A. A. Ekaykin

2017-01-01

Full Text Available The present-day global climate changes, very likely caused by anthropogenic activity, may potentially present a serious threat to the whole human civilization in a near future. In order to develop a plan of measures aimed at elimination of these threats and adaptation to these undesirable changes, one should deeply understand the mechanism of past and present (and thus, future climatic changes of our planet. In this study we compare the present-day data of instrumental observations of the air temperature and snow accumulation rate performed in Central Antarctica (the Vostok station with the reconstructed paleogeographic data on a variability of these parameters in the past. First of all, the Vostok station is shown to be differing from other East Antarctic stations due to relatively higher rate of warming (1.6 °C per 100 years since 1958. At the same time, according to paleogeographic data, from the late eighteenth century to early twenty-first one the total warming amounted to about 1 °C, which is consistent with data from other Antarctic regions. So, we can make a conclusion with high probability that the 30-year period of 1985–2015 was the warmest over the last 2.5 centuries. As for the snow accumulation rate, the paleogeographic data on this contain a certain part of noise that does not allow reliable concluding. However, we found a statistically significant relationship between the rate of snow accumulation and air temperature. This means that with further rise of temperature in Central Antarctica, the rate of solid precipitation accumulation will increase there, thus partially compensating increasing of the sea level.

Before the freeze: otoliths from the Eocene of Seymour Island, Antarctica, reveal dominance of gadiform fishes (Teleostei).

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Schwarzhans, Werner; Mörs, Thomas; Engelbrecht, Andrea; Reguero, Marcelo; Kriwet, Jürgen

2017-01-01

The first record of fossil teleostean otoliths from Antarctica is reported. The fossils were obtained from late Early Eocene shell beds of the La Meseta Formation, Seymour Island that represent the last temperate marine climate phase in Antarctica prior to the onset of cooling and subsequent glaciation during the late Eocene. A total of 17 otolith-based teleost taxa are recognized, with 10 being identifiable to species level containing nine new species and one new genus: Argentina antarctica sp. nov., Diaphus? marambionis sp. nov., Macruronus eastmani sp. nov., Coelorinchus balushkini sp. nov., Coelorinchus nordenskjoeldi sp. nov., Palimphemus seymourensis sp. nov., Hoplobrotula? antipoda sp. nov., Notoberyx cionei gen. et sp. nov. and Cepola anderssoni sp. nov. Macruronus eastmani sp. nov. is also known from the late Eocene of Southern Australia, and Tripterophycis immutatus Schwarzhans, widespread in the southern oceans during the Eocene, has been recorded from New Zealand, southern Australia, and now Antarctica. The otolith assemblage shows a typical composition of temperate fishes dominated by gadiforms, very similar at genus and family levels to associations known from middle Eocene strata of New Zealand and the late Eocene of southern Australia, but also to the temperate Northern Hemisphere associations from the Paleocene of Denmark. The Seymour Island fauna bridges a gap in the record of global temperate marine teleost faunas during the early Eocene climate maximum. The dominant gadiforms are interpreted as the main temperate faunal component, as in the Paleocene of Denmark. Here they are represented by the families Moridae, Merlucciidae (Macruroninae), Macrouridae and Gadidae. Nowadays Gadidae are a chiefly Northern Hemisphere temperate family. Moridae, Macruroninae and Macrouridae live today on the lower shelf to deep-water or mesopelagically with Macruroninae being restricted to the Southern Ocean. The extant endemic Antarctic gadiform family

Bacterial diversity of autotrophic enriched cultures from remote, glacial Antarctic, Alpine and Andean aerosol, snow and soil samples

Science.gov (United States)

González-Toril, E.; Amils, R.; Delmas, R. J.; Petit, J.-R.; Komárek, J.; Elster, J.

2009-01-01

Four different communities and one culture of autotrophic microbial assemblages were obtained by incubation of samples collected from high elevation snow in the Alps (Mt. Blanc area) and the Andes (Nevado Illimani summit, Bolivia), from Antarctic aerosol (French station Dumont d'Urville) and a maritime Antarctic soil (King George Island, South Shetlands, Uruguay Station Artigas), in a minimal mineral (oligotrophic) media. Molecular analysis of more than 200 16S rRNA gene sequences showed that all cultured cells belong to the Bacteria domain. Phylogenetic comparison with the currently available rDNA database allowed sequences belonging to Proteobacteria Alpha-, Beta- and Gamma-proteobacteria), Actinobacteria and Bacteroidetes phyla to be identified. The Andes snow culture was the richest in bacterial diversity (eight microorganisms identified) and the marine Antarctic soil the poorest (only one). Snow samples from Col du Midi (Alps) and the Andes shared the highest number of identified microorganisms (Agrobacterium, Limnobacter, Aquiflexus and two uncultured Alphaproteobacteria clones). These two sampling sites also shared four sequences with the Antarctic aerosol sample (Limnobacter, Pseudonocardia and an uncultured Alphaproteobacteriaclone). The only microorganism identified in the Antarctica soil (Brevundimonas sp.) was also detected in the Antarctic aerosol. Most of the identified microorganisms had been detected previously in cold environments, marine sediments soils and rocks. Air current dispersal is the best model to explain the presence of very specific microorganisms, like those identified in this work, in environments very distant and very different from each other.

The Impacts of 3-D Earth Structure on GIA-Induced Crustal Deformation and Future Sea-Level Change in the Antarctic

Science.gov (United States)

Powell, E. M.; Hay, C.; Latychev, K.; Gomez, N. A.; Mitrovica, J. X.

2017-12-01

Glacial Isostatic Adjustment (GIA) models used to constrain the extent of past ice sheets and viscoelastic Earth structure, or to correct geodetic and geological observables for ice age effects, generally only consider depth-dependent variations in Earth viscosity and lithospheric structure. A et al. [2013] argued that 3-D Earth structure could impact GIA observables in Antarctica, but concluded that the presence of such structure contributes less to GIA uncertainty than do differences in Antarctic deglaciation histories. New seismic and geological evidence, however, indicates the Antarctic is underlain by complex, high amplitude variability in viscoelastic structure, including a low viscosity zone (LVZ) under West Antarctica. Hay et al. [2016] showed that sea-level fingerprints of modern melting calculated using such Earth models differ from those based on elastic or 1-D viscoelastic Earth models within decades of melting. Our investigation is motivated by two questions: (1) How does 3-D Earth structure, especially this LVZ, impact observations of GIA-induced crustal deformation associated with the last deglaciation? (2) How will 3-D Earth structure affect predictions of future sea-level rise in Antarctica? We compute the gravitationally self-consistent sea level, uplift, and gravity changes using the finite volume treatment of Latychev et al. [2005]. We consider four viscoelastic Earth models: a global 1-D model; a regional, West Antarctic-like 1-D model; a 3-D model where the lithospheric thickness varies laterally; and a 3-D model where both viscosity and lithospheric thickness vary laterally. For our Last Glacial Maximum to present investigations we employ ICE6g [Peltier et al., 2015]. For our present-future investigations we consider a melt scenario consistent with GRACE satellite gravity derived solutions [Harig et al., 2015]. Our calculations indicate that predictions of crustal deformations due to both GIA and ongoing melting are strongly influenced by 3-D

Climate Change at the Poles: Research Immersion Experience at Bellingshausen, Antarctica

Science.gov (United States)

Alexeev, V. A.; Repina, I. A.; Baeseman, J. L.; Fernandoy, F.; Bart, S.

2010-12-01

We brought a party of 15 scientists, graduate students, and educators to King George Island, the largest of the South Shetland Islands, just off the Antarctic Peninsula, for an international workshop on Antarctica and global climate change in January 2010. Participants included professors, young scientists and graduate students from the Obukhov Institute of Atmospheric Physics, the University of Maryland, the University of Wisconsin, and the Michigan Technological University. Lindsay Bartholomew, an education and outreach specialist at the Museum of Science and Industry in Chicago connected the workshop via video and Internet with an audience of museum visitors. Scientists living and working at Bellingshausen, including Hans-Ulrich Peter, an eminent ecologist from Jena University (Germany), and Bulat Movlyudov (Institute of Geography, Moscow), a distinguished glaciologist, participated in the workshop. Field trips led by Peter and Movlyudov and others were made by day and lectures were held by night. Professors and graduate students made cutting-edge presentations on such subjects as permafrost, glaciology, and global climate models. Three workshop teams conducted field research projects at the foot of the Bellingshausen Dome icecap - two on carbon cycling and one on permafrost. Major funding sources for the workshop included the Russian Foundation for Basic Research (Russia), Wilderness Research Foundation (USA), NSF, University of Wisconsin at Stevens Point, Alfred Wegener Institute (Germany) and Museum for Science and Industry (Chicago). INACH, the Chilean Antarctic Institute, and IAU, the Uruguayan Antarctic Institute, provided air charter services. On King George Island, our group was billeted at Russia’s Bellingshausen science station.

New Crustal Boundary Revealed Beneath the Ross Ice Shelf, Antarctica, through ROSETTA-Ice Integrated Aerogeophysics, Geology, and Ocean Research

Science.gov (United States)

Tinto, K. J.; Siddoway, C. S.; Bell, R. E.; Lockett, A.; Wilner, J.

2017-12-01

Now submerged within marine plateaus and rises bordering Antarctica, Australia and Zealandia, the East Gondwana accretionary margin was a belt of terranes and stitched by magmatic arcs, later stretched into continental ribbons separated by narrow elongate rifts. This crustal architecture is known from marine geophysical exploration and ocean drilling of the mid-latitude coastal plateaus and rises. A concealed sector of the former East Gondwana margin that underlies the Ross Ice Shelf (RIS), Antarctica, is the focus of ROSETTA-ICE, a new airborne data acquisition campaign that explores the crustal makeup, tectonic boundaries and seafloor bathymetry beneath RIS. Gravimeters and a magnetometer are deployed by LC130 aircraft surveying along E-W lines spaced at 10 km, and N-S tie lines at 55 km, connect 1970s points (RIGGS) for controls on ocean depth and gravity. The ROSETTA-ICE survey, 2/3 completed thus far, provides magnetic anomalies, Werner depth-to-basement solutions, a new gravity-based bathymetric model at 20-km resolution, and a new crustal density map tied to the 1970s data. Surprisingly, the data reveal that the major lithospheric boundary separating East and West Antarctica lies 300 km east of the Transantarctic Mountains, beneath the floating RIS. The East and West regions have contrasting geophysical characteristics and bathymetry, with relatively dense lithosphere, low amplitude magnetic anomalies, and deep bathymetry on the East Antarctica side, and high amplitude magnetic anomalies, lower overall density and shallower water depths on the West Antarctic side. The Central High, a basement structure cored at DSDP Site 270 and seismically imaged in the Ross Sea, continues beneath RIS as a faulted but coherent crustal ribbon coincident with the tectonic boundary. The continuity of Gondwana margin crustal architecture discovered beneath the West Antarctic Ice Sheet requires a revision of the existing tectonic framework. The sub-RIS narrow rift basins and

Coherency Between Volume Transport in the Antarctic Circumpolar Current and Southern Hemisphere Winds

Science.gov (United States)

Makowski, Jessica; Chambers, Don; Bonin, Jennifer

2013-04-01

Previous studies have suggested that ocean bottom pressure (OBP) can be used to measure the transport variability of the Antarctic Circumpolar Current (ACC). The OBP observations from the Gravity Recovery and Climate Experiment (GRACE) will be used to calculate transport along the 150°E longitude choke point, between Antarctica and Australia. We will examine whether zonally averaged wind stress, wind stress curl, or local zonal winds are more coherent with zonal mass transport variability. Preliminary studies suggest that seasonal variation in transport across 150°E is more correlated with winds along and north of the northern front of the ACC: the Sub Tropical front (STF). It also appears that interannual variations in transport along 150°E are related to wind variations south of the STF and centered south of the Sub Antarctic Front (SAF). We have observed a strong anti-correlation across the SAF, in the Indian Ocean, which suggests wind stress curl may also be responsible for transport variations. Preliminary results will be presented.

Tardigrade eggs and exuviae in Antarctic lake sediments: insights into Holocene dynamics and origins of the fauna

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Sandra J. MCINNES

2007-09-01

Full Text Available The preservation of tardigrade eggs and exuviae in Antarctic lake sediments provided an opportunity to assess post-glacial colonisation and Holocene tardigrade dynamics on the southern continent. Tardigrade eggs were recovered from five lakes, two from the maritime Antarctic and three from continental Antarctica. Eggs were identified from the following species: Dactylobiotus cf. ambiguus, Macrobiotus furciger, Macrobiotus blocki, Minibiotus weinerorum and Acutuncus antarcticus. Other, unornamented eggs were also observed. The preservation of some of these eggs in exuviae allowed identification to at least genus. Significant variations were observed in egg abundance within the sediment of each lake, and in one lake a species (Dactylobiotus cf. ambiguus became locally extinct, probably as the result of penguin-associated eutrophication. Tardigrades generally did not become abundant for a considerable period after the lakes’ formation. The presence of an in-part endemic fauna is consistent with slow colonisation from Antarctic sources rather than wind transport from extra-continental sites. Tardigrade eggs appear to be abundant in high-latitude lake sediments, and greater use could be made of these records when evaluating tardigrade dynamics during the Holocene.

A 40-year accumulation dataset for Adelie Land, Antarctica and its application for model validation

Energy Technology Data Exchange (ETDEWEB)

Agosta, Cecile; Favier, Vincent [UJF-Grenoble 1 / CNRS, Laboratoire de Glaciologie et de Geophysique de l' Environnement UMR 5183, Saint Martin d' Heres (France); Genthon, Christophe; Gallee, Hubert; Krinner, Gerhard [CNRS / UJF-Grenoble 1, Laboratoire de Glaciologie et de Geophysique de l' Environnement UMR 5183, Saint Martin d' Heres (France); Lenaerts, Jan T.M.; Broeke, Michiel R. van den [Utrecht University, Institute for Marine and Atmospheric Research Utrecht (Netherlands)

2012-01-15

The GLACIOCLIM-SAMBA (GS) Antarctic accumulation monitoring network, which extends from the coast of Adelie Land to the Antarctic plateau, has been surveyed annually since 2004. The network includes a 156-km stake-line from the coast inland, along which accumulation shows high spatial and interannual variability with a mean value of 362 mm water equivalent a{sup -1}. In this paper, this accumulation is compared with older accumulation reports from between 1971 and 1991. The mean and annual standard deviation and the km-scale spatial pattern of accumulation were seen to be very similar in the older and more recent data. The data did not reveal any significant accumulation trend over the last 40 years. The ECMWF analysis-based forecasts (ERA-40 and ERA-Interim), a stretched-grid global general circulation model (LMDZ4) and three regional circulation models (PMM5, MAR and RACMO2), all with high resolution over Antarctica (27-125 km), were tested against the GS reports. They qualitatively reproduced the meso-scale spatial pattern of the annual-mean accumulation except MAR. MAR significantly underestimated mean accumulation, while LMDZ4 and RACMO2 overestimated it. ERA-40 and the regional models that use ERA-40 as lateral boundary condition qualitatively reproduced the chronology of interannual variability but underestimated the magnitude of interannual variations. Two widely used climatologies for Antarctic accumulation agreed well with the mean GS data. The model-based climatology was also able to reproduce the observed spatial pattern. These data thus provide new stringent constraints on models and other large-scale evaluations of the Antarctic accumulation. (orig.)

Detection of Evolutionarily Distinct Avian Influenza A Viruses in Antarctica

Science.gov (United States)

Vijaykrishna, Dhanasekaran; Butler, Jeffrey; Baas, Chantal; Maurer-Stroh, Sebastian; Silva-de-la-Fuente, M. Carolina; Medina-Vogel, Gonzalo; Olsen, Bjorn; Kelso, Anne; Barr, Ian G.; González-Acuña, Daniel

2014-01-01

ABSTRACT Distinct lineages of avian influenza viruses (AIVs) are harbored by spatially segregated birds, yet significant surveillance gaps exist around the globe. Virtually nothing is known from the Antarctic. Using virus culture, molecular analysis, full genome sequencing, and serology of samples from Adélie penguins in Antarctica, we confirmed infection by H11N2 subtype AIVs. Their genetic segments were distinct from all known contemporary influenza viruses, including South American AIVs, suggesting spatial separation from other lineages. Only in the matrix and polymerase acidic gene phylogenies did the Antarctic sequences form a sister relationship to South American AIVs, whereas distant phylogenetic relationships were evident in all other gene segments. Interestingly, their neuraminidase genes formed a distant relationship to all avian and human influenza lineages, and the polymerase basic 1 and polymerase acidic formed a sister relationship to the equine H3N8 influenza virus lineage that emerged during 1963 and whose avian origins were previously unknown. We also estimated that each gene segment had diverged for 49 to 80 years from its most closely related sequences, highlighting a significant gap in our AIV knowledge in the region. We also show that the receptor binding properties of the H11N2 viruses are predominantly avian and that they were unable to replicate efficiently in experimentally inoculated ferrets, suggesting their continuous evolution in avian hosts. These findings add substantially to our understanding of both the ecology and the intra- and intercontinental movement of Antarctic AIVs and highlight the potential risk of an incursion of highly pathogenic AIVs into this fragile environment. PMID:24803521

Concordia, Antarctica, seismic experiment for the International Polar Year (CASE-IPY

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Alessia Maggi

2014-06-01

Full Text Available The CASE-IPY project, part of the larger POLENET initiative of geophysical observations for the International Polar Year, was built on our extensive experience of running seismological stations in Antarctica, both on rock sites (Dumont d’Urville station, and directly on the ice plateau (Concordia station. For CASE-IPY, we deployed 8 temporary seismic stations on the Antarctic plateau: 3 situated near Concordia itself (starting 2008, and the other 5 regularly spaced between Concordia and Vostok (2010-2012, following the maximum in ice topography. The technical problems we have encountered in our field deployments were essentially due to a combination of extreme environmental conditions and isolation of deployment sites. The 3 stations near Concordia were used as test sites to experiment different solutions, and to converge on a design for the 5 main stations. Results from the nearest stations, which transmit data regularly to Concordia, are very promising. The data recorded by our stations will be distributed widely in the scientific community. We expect them to be exploited essentially for structural studies involving Antarctica itself (its ice-cap, crust and lithosphere via receiver functions, noise correlation, and surface-wave tomography, but also for studies of the Earth’s core.

Overview and Assessment of Antarctic Ice-Sheet Mass Balance Estimates: 1992-2009

Science.gov (United States)

Zwally, H. Jay; Giovinetto, Mario B.

2011-01-01

Mass balance estimates for the Antarctic Ice Sheet (AIS) in the 2007 report by the Intergovernmental Panel on Climate Change and in more recent reports lie between approximately ?50 to -250 Gt/year for 1992 to 2009. The 300 Gt/year range is approximately 15% of the annual mass input and 0.8 mm/year Sea Level Equivalent (SLE). Two estimates from radar altimeter measurements of elevation change by European Remote-sensing Satellites (ERS) (?28 and -31 Gt/year) lie in the upper part, whereas estimates from the Input-minus-Output Method (IOM) and the Gravity Recovery and Climate Experiment (GRACE) lie in the lower part (-40 to -246 Gt/year). We compare the various estimates, discuss the methodology used, and critically assess the results. We also modify the IOM estimate using (1) an alternate extrapolation to estimate the discharge from the non-observed 15% of the periphery, and (2) substitution of input from a field data compilation for input from an atmospheric model in 6% of area. The modified IOM estimate reduces the loss from 136 Gt/year to 13 Gt/year. Two ERS-based estimates, the modified IOM, and a GRACE-based estimate for observations within 1992 2005 lie in a narrowed range of ?27 to -40 Gt/year, which is about 3% of the annual mass input and only 0.2 mm/year SLE. Our preferred estimate for 1992 2001 is -47 Gt/year for West Antarctica, ?16 Gt/year for East Antarctica, and -31 Gt/year overall (?0.1 mm/year SLE), not including part of the Antarctic Peninsula (1.07% of the AIS area). Although recent reports of large and increasing rates of mass loss with time from GRACE-based studies cite agreement with IOM results, our evaluation does not support that conclusion

[Microbiological analysis of terrestrial biotopes of the Antarctic region].

Science.gov (United States)

Tashirev, A B; Romanovskaia, V A; Rokitko, P V; Shilin, S O; Chernaia, N A; Tashireva, A A

2010-01-01

Microbiological analysis has been made of 120 samples from biotopes of the western coast of the Antarctic peninsula (Rasmussen cope, Tuxen cope, Waugh mountain), Argentine archipelago islands (Galindez, Skua, Corner, Barchans, Irizar, Uruguay, Cluls, Three Little Pigs, King-George), as well as neighbouring islands (Petermann--on the north, a group of Jalour islands--on the east, Berthelot--on the south-east); and more remote islands (Darboux, Lippmann, Booth). It was found out that the total number of chemoorganotrophic aerobic microorganisms was 10(6) - 10(8) cells/g of soil, that was by 2-3 orders lower than in the regions with temperate climate. One can observe a tendency of decreasing the quantity of chemoorganotrophic microorganisms in the Antartic biotopes (cells/g of a sample) in the following order: soil (1 x 10(7) - 8 x 10(8)), underground part of moss (1 x 10(6) - 5 x 10(7)), grass Deschampsia antarctica (10(6) - 10(8), slit of fresh-water reservoir (10(5) - 10(7)), ground part of moss (10(3) - 10(6)), lichens (10(3) - 10(6)). Representatives of several phylogenetic lines: Proteobacteria (genera Pseudomonas, Methylobacterium, Enterobacter), Firmicutes (genera Bacillus, Staphylococcus), Actinobacteria (genera Brevibacterium, Actinomyces, Streptomyces) have been found in the Antarctic samples. As a rule, genera of bacteria found in the Antarctic Region are widely distributed in different regions of the Earth with temperate climate. Microorganisms similar to the species Exophiala nigra (Issatsch.) Haats et de Hoog 1999, which was first detected 100 years ago by Academician B.L. Isachenko in the Arctic region water, were also isolated from biofilms on vertical rocks of the Galindez Island as well as from the soil of the Irizar Island.

The Future of the United States Antarctic Program

Science.gov (United States)

Thom, J. E.; Weidner, G. A.; Lazzara, M. A.; Knuth, S. L.; Cassano, J. J.

2009-04-01

The last three decades have seen Antarctic surface meteorological observations augmented by an increasing number of automated weather stations (AWS). Since 1980, the University of Wisconsin-Madison has managed an expanding array of AWS in Antarctica that are funded through the United States' National Science Foundation. The AWS network began with six stations and has grown to approximately 60 stations. The majority of the AWS use a custom electronics package designed in the 1970s and modified over approximately 20 years. However, dramatic changes in the electronics industry have led the UW-Madison to transition its AWS to commercial-off-the-shelf (COTS) components capable of integrating on-station storage, varied sensors, multiple data telemetry options, and a flexible operating system. Among the important technical issues arising from adopting a COTS-based AWS system are limited temperature certification for Antarctic conditions; non-standard integration of the varied telecommunications equipment; potentially inflexible data acquisition schemes; and frequent product upgrades, changes, and obsolescence. The UW-Madison presents the current status of its AWS system; its recent experience with new data loggers, sensors, and communication options; and its attempts to obtain a standardized AWS. The intent is to encourage the development of a forum where groups can document their experiences with varied AWS systems in the extreme polar climate. Recent events have added another challenge within the United States Antarctic Program, as it has become clear that budgetary and logistic limitations will drastically impact the AWS program. With logistical costs playing a bigger factor in funding AWS operations, international coordination and cooperation will be important in deploying and maintaining the AWS networks (such as GCOS) that are critical to monitoring the world's climate.

Black carbon at a coastal Antarctic station (Syowa Station: seasonal variation and transport processes

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Keiichiro Hara

2010-12-01

Full Text Available Measurement of atmospheric black carbon (BC was carried out at Syowa Station Antarctica (69゜00′S, 39゜35′E from February 2004 until January 2007. The BC concentration at Syowa Station ranged from below detection to 176 ng m^. Higher BC concentrations were observed frequently from April until October. Increase of BC concentration may be associated with poleward flow due to the approach of a cyclone and or blocking event during winter-spring. The BC-rich air masses traveled through the lower troposphere from the Atlantic and Indian Oceans to Syowa (Antarctic coast. During the summer (November-February, the BC concentration showed a diurnal variation together with surface wind speed and increased in the presence of katabatic wind from the Antarctic continent. Considering the low BC source strength over the Antarctic continent, the higher BC concentration in the continental air (katabatic wind might be caused by long range transport of BC via the free troposphere from mid- and low- latitudes. The seasonal variation of BC at Syowa Station had a maximum in July-September, while at the other coastal stations (Halley, Neumayer, and Ferraz and a continental station (Amundsen-Scott, the maximum occurred in October. This difference may result from different transport pathways, significant contribution of source regions and scavenging of BC by precipitation during the transport from the source regions. During the austral summer, long-range transport of BC via the free troposphere is likely to make an important contribution to the ambient BC concentration along the Antarctic coasts.

Geodetic antenna calibration test in the Antarctic environment

Science.gov (United States)

Grejner-Brzezinska, A.; Vazquez, E.; Hothem, L.

2006-01-01

TransAntarctic Mountain DEFormation (TAMDEF) Monitoring Network is the NSF-sponsored OSU and USGS project, aimed at measuring crustal motion in the Transantarctic Mountains of Victoria Land using GPS carrier phase measurements. Station monumentation, antenna mounts, antenna types, and data processing strategies were optimized to achieve mm-level estimates for the rates of motion. These data contributes also to regional Antarctic frame definition. Significant amount of data collected over several years allow the investigation of unique aspects of GPS geodesy in Antarctica, to determine how the error spectrum compares to the mid-latitude regions, and to identify the optimum measurement and data processing schemes for Antarctic conditions, in order to test the predicted rates of motion (mm-level w.r.t. time). The data collection for the TAMDEF project was initiated in 1996. The primary antenna used has been the Ashtech L1/L2 Dorne Margolin (D/M) choke ring. A few occupations involved the use of a Trimble D/M choke ring. The data were processed using the antenna calibration data available from the National Geodetic Survey (NGS). The recent developments in new antenna designs that are lighter in weight and lower in cost are being considered as a possible alternative to the bulkier and more expensive D/M choke ring design. In November 2003, in situ testing of three alternative models of L1/L2 antennas was conducted at a site located in the vicinity of McMurdo Station, Antarctica (S77.87, E166.56). The antenna models used in this test were: Ashtech D/M choke ring, Trimble D/M choke ring, Trimble Zephyr, and the NovAtel GPS-702. Two stations, spaced within 30 meters, were used in the test. Both had the characteristics similar to the stations of the TAMDEF network, i.e., the UNAVCO fixed-height, force-centered level mounts with a constant antenna offset were used, ensuring extreme stability of the antenna/ mount/pin set up. During each of the four 3-day test data collection

Levels and pattern of polybrominated diphenyl ethers in eggs of Antarctic seabirds: Endemic versus migratory species

Energy Technology Data Exchange (ETDEWEB)

Yogui, G.T. [Geochemical and Environmental Research Group, College of Geosciences, Texas A and M University, 833 Graham Road, College Station, TX 77845 (United States)], E-mail: gtyogui@ocean.tamu.edu; Sericano, J.L. [Geochemical and Environmental Research Group, College of Geosciences, Texas A and M University, 833 Graham Road, College Station, TX 77845 (United States)], E-mail: jsericano@gerg.tamu.edu

2009-03-15

Chinstrap and gentoo penguins are endemic species that live year round south of the Antarctic Convergence. South polar skua is a migratory seabird that can be observed in Antarctica during the breeding season (i.e., austral summer). This study compares concentration and pattern of polybrominated diphenyl ethers (PBDEs) in eggs of seabirds breeding at King George Island, Antarctic Peninsula. PBDEs in south polar skua eggs are approximately 20 times higher than in penguin eggs suggesting that skuas are more exposed to contaminants during the non-breeding season when they migrate to waters of the northern hemisphere. The pattern of PBDE congeners also differs between south polar skua and penguin eggs. The latter exhibited a pattern similar to that found in the local biota. In contrast, the congener pattern in south polar skua eggs suggests that birds breeding at King George Island may winter in the northwestern Pacific Ocean. - Skua and penguin eggs collected at King George Island have different concentration and pattern of PBDEs.

Levels and pattern of polybrominated diphenyl ethers in eggs of Antarctic seabirds: Endemic versus migratory species

International Nuclear Information System (INIS)

Yogui, G.T.; Sericano, J.L.

2009-01-01

Chinstrap and gentoo penguins are endemic species that live year round south of the Antarctic Convergence. South polar skua is a migratory seabird that can be observed in Antarctica during the breeding season (i.e., austral summer). This study compares concentration and pattern of polybrominated diphenyl ethers (PBDEs) in eggs of seabirds breeding at King George Island, Antarctic Peninsula. PBDEs in south polar skua eggs are approximately 20 times higher than in penguin eggs suggesting that skuas are more exposed to contaminants during the non-breeding season when they migrate to waters of the northern hemisphere. The pattern of PBDE congeners also differs between south polar skua and penguin eggs. The latter exhibited a pattern similar to that found in the local biota. In contrast, the congener pattern in south polar skua eggs suggests that birds breeding at King George Island may winter in the northwestern Pacific Ocean. - Skua and penguin eggs collected at King George Island have different concentration and pattern of PBDEs

Snow precipitation at four ice core sites in East Antarctica: provenance, seasonality and blocking factors

Energy Technology Data Exchange (ETDEWEB)

Scarchilli, Claudio [ENEA, Rome (Italy); Universita degli studi di Trieste, Trieste (Italy); Frezzotti, Massimo; Ruti, Paolo Michele [ENEA, Rome (Italy)

2011-11-15

Snow precipitation is the primary mass input to the Antarctic ice sheet and is one of the most direct climatic indicators, with important implications for paleoclimatic reconstruction from ice cores. Provenance of precipitation and the dynamic conditions that force these precipitation events at four deep ice core sites (Dome C, Law Dome, Talos Dome, and Taylor Dome) in East Antarctica were analysed with air mass back trajectories calculated using the Lagrangian model and the mean composite data for precipitation, geopotential height and wind speed field data from the European Centre for Medium Range Weather Forecast from 1980 to 2001. On an annual basis, back trajectories showed that the Atlantic-Indian and Ross-Pacific Oceans were the main provenances of precipitation in Wilkes Land (80%) and Victoria Land (40%), respectively, whereas the greatest influence of the ice sheet was on the interior near the Vostok site (80%) and in the Southwest Ross Sea (50%), an effect that decreased towards the coast and along the Antarctic slope. Victoria Land received snowfall atypically with respect to other Antarctica areas in terms of pathway (eastern instead of western), seasonality (summer instead of winter) and velocity (old air age). Geopotential height patterns at 500 hPa at low (>10 days) and high (2-6 days) frequencies during snowfall cycles at two core sites showed large positive anomalies at low frequencies developing in the Tasman Sea-Eastern Indian Ocean at higher latitudes (60-70 S) than normal. This could be considered part of an atmospheric blocking event, with transient eddies acting to decelerate westerlies in a split region area and accelerate the flow on the flanks of the low-frequency positive anomalies. (orig.)

An Antarctic research outpost as a model for planetary exploration.

Science.gov (United States)

Andersen, D T; McKay, C P; Wharton, R A; Rummel, J D

1990-01-01

During the next 50 years, human civilization may well begin expanding into the solar system. This colonization of extraterrestrial bodies will most likely begin with the establishment of small research outposts on the Moon and/or Mars. In all probability these facilities, designed primarily for conducting exploration and basic science, will have international participation in their crews, logistical support and funding. High fidelity Earth-based simulations of planetary exploration could help prepare for these expensive and complex operations. Antarctica provides one possible venue for such a simulation. The hostile and remote dry valleys of southern Victoria Land offer a valid analog to the Martian environment but are sufficiently accessible to allow routine logistical support and to assure the relative safety of their inhabitants. An Antarctic research outpost designed as a planetary exploration simulation facility would have great potential as a testbed and training site for the operation of future Mars bases and represents a near-term, relatively low-cost alternative to other precursor activities. Antarctica already enjoys an international dimension, an aspect that is more than symbolically appropriate to an international endeavor of unprecedented scientific and social significance--planetary exploration by humans. Potential uses of such a facility include: 1) studying human factors in an isolated environment (including long-term interactions among an international crew); 2) testing emerging technologies (e.g., advanced life support facilities such as a partial bioregenerative life support system, advanced analytical and sample acquisition instrumentation and equipment, etc.); and 3) conducting basic scientific research similar to the research that will be conducted on Mars, while contributing to the planning for human exploration. (Research of this type is already ongoing in Antarctica).

Diversity structure of culturable bacteria isolated from the Fildes Peninsula (King George Island, Antarctica): A phylogenetic analysis perspective.

Science.gov (United States)

González-Rocha, Gerardo; Muñoz-Cartes, Gabriel; Canales-Aguirre, Cristian B; Lima, Celia A; Domínguez-Yévenes, Mariana; Bello-Toledo, Helia; Hernández, Cristián E

2017-01-01

It has been proposed that Antarctic environments select microorganisms with unique biochemical adaptations, based on the tenet 'Everything is everywhere, but, the environment selects' by Baas-Becking. However, this is a hypothesis that has not been extensively evaluated. This study evaluated the fundamental prediction contained in this hypothesis-in the sense that species are structured in the landscape according to their local habitats-, using as study model the phylogenetic diversity of the culturable bacteria of Fildes Peninsula (King George Island, Antarctica). Eighty bacterial strains isolated from 10 different locations in the area, were recovered. Based on phylogenetic analysis of 16S rRNA gene sequences, the isolates were grouped into twenty-six phylotypes distributed in three main clades, of which only six are exclusive to Antarctica. Results showed that phylotypes do not group significantly by habitat type; however, local habitat types had phylogenetic signal, which support the phylogenetic niche conservatism hypothesis and not a selective role of the environment like the Baas-Becking hypothesis suggests. We propose that, more than habitat selection resulting in new local adaptations and diversity, local historical colonization and species sorting (i.e. differences in speciation and extinction rates that arise by interaction of species level traits with the environment) play a fundamental role on the culturable bacterial diversity in Antarctica.

Geospatial variability of soil CO2-C exchange in the main terrestrial ecosystems of Keller Peninsula, Maritime Antarctica.

Science.gov (United States)

Thomazini, A; Francelino, M R; Pereira, A B; Schünemann, A L; Mendonça, E S; Almeida, P H A; Schaefer, C E G R

2016-08-15

Soils and vegetation play an important role in the carbon exchange in Maritime Antarctica but little is known on the spatial variability of carbon processes in Antarctic terrestrial environments. The objective of the current study was to investigate (i) the soil development and (ii) spatial variability of ecosystem respiration (ER), net ecosystem CO2 exchange (NEE), gross primary production (GPP), soil temperature (ST) and soil moisture (SM) under four distinct vegetation types and a bare soil in Keller Peninsula, King George Island, Maritime Antarctica, as follows: site 1: moss-turf community; site 2: moss-carpet community; site 3: phanerogamic antarctic community; site 4: moss-carpet community (predominantly colonized by Sanionia uncinata); site 5: bare soil. Soils were sampled at different layers. A regular 40-point (5×8 m) grid, with a minimum separation distance of 1m, was installed at each site to quantify the spatial variability of carbon exchange, soil moisture and temperature. Vegetation characteristics showed closer relation with soil development across the studied sites. ER reached 2.26μmolCO2m(-2)s(-1) in site 3, where ST was higher (7.53°C). A greater sink effect was revealed in site 4 (net uptake of 1.54μmolCO2m(-2)s(-1)) associated with higher SM (0.32m(3)m(-3)). Spherical models were fitted to describe all experimental semivariograms. Results indicate that ST and SM are directly related to the spatial variability of CO2 exchange. Heterogeneous vegetation patches showed smaller range values. Overall, poorly drained terrestrial ecosystems act as CO2 sink. Conversely, where ER is more pronounced, they are associated with intense soil carbon mineralization. The formations of new ice-free areas, depending on the local soil drainage condition, have an important effect on CO2 exchange. With increasing ice/snow melting, and resulting widespread waterlogging, increasing CO2 sink in terrestrial ecosystems is expected for Maritime Antarctica. Copyright �

The effects of greenhouse gases on the Antarctic ozone hole in the past, present, and future

Science.gov (United States)

Newman, P. A.; Li, F.; Lait, L. R.; Oman, L.

2017-12-01

The Antarctic ozone hole is primarily caused by human-produced ozone depleting substances such as chlorine-containing chlorofluorocarbons (CFCs) and bromine-containing halons. The large ozone spring-time depletion relies on the very-cold conditions of the Antarctic lower stratosphere, and the general containment of air by the polar night jet over Antarctica. Here we show the Goddard Earth Observing System Chemistry Climate Model (GEOSCCM) coupled ocean-atmosphere-chemistry model for exploring the impact of increasing greenhouse gases (GHGs). Model simulations covering the 1960-2010 period are shown for: 1) a control ensemble with observed levels of ODSs and GHGs, 2) an ensemble with fixed 1960 GHG concentrations, and 3) an ensemble with fixed 1960 ODS levels. We look at a similar set of simulations (control, 2005 fixed GHG levels, and 2005 fixed ODS levels) with a new version of GEOSCCM over the period 2005-2100. These future simulations show that the decrease of ODSs leads to similar ozone recovery for both the control run and the fixed GHG scenarios, in spite of GHG forced changes to stratospheric ozone levels. These simulations demonstrate that GHG levels will have major impacts on the stratosphere by 2100, but have only small impacts on the Antarctic ozone hole.

Spatial Variability of Perchlorate along a Traverse Route from Zhongshan Station to Dome A, East Antarctica

Science.gov (United States)

Jiang, S.; Cole-Dai, J.; Li, Y.; An, C.

2016-12-01

Snow deposition and accumulation on the Antarctic ice sheet preserve records of climatic change, as well as those of chemical characteristics of the environment. Chemical composition of snow and ice cores can be used to track the sources of important substances including pollutants and to investigate relationships between atmospheric chemistry and climatic conditions. Recent development in analytical methodology has enabled the determination of ultra-trace levels of perchlorate in polar snow. We have measured perchlorate concentrations in surface snow samples collected along a traverse route from Zhongshan Station to Dome A in East Antarctica to determine the level of atmospheric perchlorate in East Antarctica and to assess the spatial variability of perchlorate along the traverse route. Results show that the perchlorate concentrations vary between 32 and 200 ng kg-1, with an average of 104.3 ng kg-1. And perchlorate concentration profile presents regional variation patterns along the traverse route. In the coastal region, perchlorate concentration displays an apparent decreasing relationship with increasing distance inland; it exhibits no apparent trend in the intermediate region from 200 to 1000 km. The inland region from 1000 to 1244 km presents a generally increasing trend of perchlorate concentration approaching the dome. Different rates of atmospheric production, dilution by snow accumulation and re-deposition of snow-emitted perchlorate (post-depositional change) are the three possible factors influencing the spatial variability of perchlorate over Antarctica.

Vitamin D Supplementation and Immune Response to Antarctic Winter

Science.gov (United States)

Zwart, S. R.; Mehta, S. K.; Ploutz-Snyder, R.; Bourbeau, Y.; Locke, J. P.; Pierson, D. L.; Smith, Scott M.

2011-01-01

Maintaining vitamin D status without sunlight exposure is difficult without supplementation. This study was designed to better understand interrelationships between periodic cholecalciferol(vitamin D3) supplementation and immune function in Antarctic workers. The effect of 2 oral dosing regimens of vitamin D3 supplementation on vitamin D status and markers of immune function were evaluated in people in Antarctica with no ultraviolet light exposure for 6 mo. Participants were given a 2,000-IU (50 g) daily (n=15) or 10,000-IU (250 g) weekly (n=14) vitamin D3 supplement for 6 mo during a winter in Antarctica. Biological samples were collected at baseline and at 3 and 6 mo. Vitamin D intake, markers of vitamin D and bone metabolism, and latent virus reactivation were determined. After 6 mo the mean (SD) serum 25-hydroxyvitamin D3 concentration increased from 56 plus or minus 17 to 79 plus or minus 16 nmol/L and 52 plus or minus 10 to 69 plus or minus 9 nmol/L in the 2,000-IU/d and 10,000-IU/wk groups (main effect over time P less than 0.001). Participants with a greater BMI (participant BMI range = 19-43 grams per square meter) had a smaller increase in 25-hydroxyvitamin D3 after 6 mo supplementation (P less than 0.05). Participants with high serum cortisoland higher serum 25-hydroxyvitamin D3 were less likely to shed Epstein-Barr virus in saliva (P less than 0.05). The doses given raised vitamin D status in participants not exposed to sunlight for 6 mo, and the efficacy was influenced by baseline vitamin D status and BMI. The data also provide evidence that vitamin D, interacting with stress, can reduce risk of latent virus reactivation during the winter in Antarctica.

Photosynthesis and Bioconversion

International Nuclear Information System (INIS)

Broda, E.

1983-01-01

This text summarises a talk held by Engelbert Broda at a conference on non-convential energy sources. The talk about photosynthesis and bioconversion is devided in 6 sections: the great physicist and photosynthesis; the influence of photosynthesis on the biosphere (in the past, present and future); the light reactions in photosynthesis; the dark reactions in photosynthesis; bioconversion; respiration and photorespiration. (nowak)

Validation of Airborne FMCW Radar Measurements of Snow Thickness Over Sea Ice in Antarctica

Science.gov (United States)

Galin, Natalia; Worby, Anthony; Markus, Thorsten; Leuschen, Carl; Gogineni, Prasad

2012-01-01

Antarctic sea ice and its snow cover are integral components of the global climate system, yet many aspects of their vertical dimensions are poorly understood, making their representation in global climate models poor. Remote sensing is the key to monitoring the dynamic nature of sea ice and its snow cover. Reliable and accurate snow thickness data are currently a highly sought after data product. Remotely sensed snow thickness measurements can provide an indication of precipitation levels, predicted to increase with effects of climate change in the polar regions. Airborne techniques provide a means for regional-scale estimation of snow depth and distribution. Accurate regional-scale snow thickness data will also facilitate an increase in the accuracy of sea ice thickness retrieval from satellite altimeter freeboard estimates. The airborne data sets are easier to validate with in situ measurements and are better suited to validating satellite algorithms when compared with in situ techniques. This is primarily due to two factors: better chance of getting coincident in situ and airborne data sets and the tractability of comparison between an in situ data set and the airborne data set averaged over the footprint of the antennas. A 28-GHz frequency modulated continuous wave (FMCW) radar loaned by the Center for Remote Sensing of Ice Sheets to the Australian Antarctic Division is used to measure snow thickness over sea ice in East Antarctica. Provided with the radar design parameters, the expected performance parameters of the radar are summarized. The necessary conditions for unambiguous identification of the airsnow and snowice layers for the radar are presented. Roughnesses of the snow and ice surfaces are found to be dominant determinants in the effectiveness of layer identification for this radar. Finally, this paper presents the first in situ validated snow thickness estimates over sea ice in Antarctica derived from an FMCW radar on a helicopterborne platform.

Laboratory study of nitrate photolysis in Antarctic snow

DEFF Research Database (Denmark)

Berhanu, Tesfaye A.; Meusinger, Carl; Erbland, Joseph

2014-01-01

in Antarctic snow. I. Observed quantum yield, domain of photolysis, and secondary chemistry," J. Chem. Phys. 140, 244305 (2014)]) is to characterize nitrate photochemistry and improve the interpretation of the nitrate ice core record. Naturally occurring stable isotopes in nitrate (15N, 17O, and 18O) provide...... additional information concerning post-depositional processes. Here, we present results from studies of the wavelength-dependent isotope effects from photolysis of nitrate in a matrix of natural snow. Snow from Dome C, Antarctica was irradiated in selected wavelength regions using a Xe UV lamp and filters....... The irradiated snow was sampled and analyzed for nitrate concentration and isotopic composition (δ 15N, δ 18O, and Δ 17O). From these measurements an average photolytic isotopic fractionation of 15ε = (- 15 ± 1.2)‰ was found for broadband Xe lamp photolysis. These results are due in part to excitation...

Empirical estimation of present-day Antarctic glacial isostatic adjustment and ice mass change

Science.gov (United States)

Gunter, B. C.; Didova, O.; Riva, R. E. M.; Ligtenberg, S. R. M.; Lenaerts, J. T. M.; King, M. A.; van den Broeke, M. R.; Urban, T.

2014-04-01

This study explores an approach that simultaneously estimates Antarctic mass balance and glacial isostatic adjustment (GIA) through the combination of satellite gravity and altimetry data sets. The results improve upon previous efforts by incorporating a firn densification model to account for firn compaction and surface processes as well as reprocessed data sets over a slightly longer period of time. A range of different Gravity Recovery and Climate Experiment (GRACE) gravity models were evaluated and a new Ice, Cloud, and Land Elevation Satellite (ICESat) surface height trend map computed using an overlapping footprint approach. When the GIA models created from the combination approach were compared to in situ GPS ground station displacements, the vertical rates estimated showed consistently better agreement than recent conventional GIA models. The new empirically derived GIA rates suggest the presence of strong uplift in the Amundsen Sea sector in West Antarctica (WA) and the Philippi/Denman sectors, as well as subsidence in large parts of East Antarctica (EA). The total GIA-related mass change estimates for the entire Antarctic ice sheet ranged from 53 to 103 Gt yr-1, depending on the GRACE solution used, with an estimated uncertainty of ±40 Gt yr-1. Over the time frame February 2003-October 2009, the corresponding ice mass change showed an average value of -100 ± 44 Gt yr-1 (EA: 5 ± 38, WA: -105 ± 22), consistent with other recent estimates in the literature, with regional mass loss mostly concentrated in WA. The refined approach presented in this study shows the contribution that such data combinations can make towards improving estimates of present-day GIA and ice mass change, particularly with respect to determining more reliable uncertainties.

Leadership in politics and science within the Antarctic Treaty

Directory of Open Access Journals (Sweden)

John R. Dudeney

2012-04-01

Full Text Available For over 50 years the Antarctic has been governed through the Antarctic Treaty, an international agreement now between 49 nations of whom 28 Consultative Parties (CPs undertake the management role. Ostensibly, these Parties have qualified for their position on scientific grounds, though diplomacy also plays a major role. This paper uses counts of policy papers and science publications to assess the political and scientific outputs of all CPs over the last 18 years. We show that a subset of the original 12 Treaty signatories, consisting of the seven claimant nations, the USA and Russia, not only set the political agenda for the continent but also provide most of the science, with those CPs producing the most science generally having the greatest political influence. None of the later signatories to the Treaty appear to play a major role in managing Antarctica compared with this group, with half of all CPs collectively producing only 7% of the policy papers. Although acceptance as a CP requires demonstration of a substantial scientific programme, the Treaty has no formal mechanism to review whether a CP continues to meet this criterion. As a first step to addressing this deficiency, we encourage the CPs collectively to resolve to hold regular international peer reviews of their individual science programmes and to make the results available to the other CPs.

The diversity, extracellular enzymatic activities and photoprotective compounds of yeasts isolated in Antarctica

Directory of Open Access Journals (Sweden)

Aline B. M Vaz

2011-09-01

Full Text Available The diversity of yeasts collected from different sites in Antarctica (Admiralty Bay, King George Island and Port Foster Bay and Deception Island and their ability to produce extracellular enzymes and mycosporines were studied. Samples were collected during the austral summer season, between November 2006 and January 2007, from the rhizosphere of Deschampsia antarctica, ornithogenic (penguin guano soil, soil, marine and lake sediments, marine water and freshwater from lakes. A total of 89 isolates belonging to the following genera were recovered: Bensingtonia, Candida, Cryptococcus, Debaryomyces, Dioszegia, Exophiala, Filobasidium, Issatchenkia (Pichia, Kodamaea, Leucosporidium, Leucosporidiella, Metschnikowia, Nadsonia, Pichia, Rhodotorula, and Sporidiobolus, and the yeast-like fungi Aureobasidium, Leuconeurospora and Microglossum. Cryptococcus victoriae was the most frequently identified species. Several species isolated in our study have been previously reported to be Antarctic psychophilic yeasts, including Cr. antarcticus, Cr. victoriae, Dioszegia hungarica and Leucosporidium scottii. The cosmopolitan yeast species A. pullulans, C. zeylanoides, D. hansenii, I. orientalis, K. ohmeri, P. guilliermondii, Rh. mucilaginosa, and S. salmonicolor were also isolated. Five possible new species were identified. Sixty percent of the yeasts had at least one detectable extracellular enzymatic activity. Cryptococcus antarcticus, D. aurantiaca, D. crocea, D. hungarica, Dioszegia sp., E. xenobiotica, Rh. glaciales, Rh. laryngis, Microglossum sp. 1 and Microglossum sp. 2 produced mycosporines. Of the yeast isolates, 41.7% produced pigments and/or mycosporines and could be considered adapted to survive in Antarctica. Most of the yeasts had extracellular enzymatic activities at 4ºC and 20ºC, indicating that they could be metabolically active in the sampled substrates.

Aves, Charadriiformes, Scolopacidae, Limosa haemastica, (Linnaeus, 1758: First record from South Shetland Islands and Antarctic Peninsula, Antarctica

Directory of Open Access Journals (Sweden)

Juares, M. A.

2010-01-01

Full Text Available We report herein the southernmost record of the Hudsonian Godwit (Limosa haemastica, at two localities inthe Antarctic: Esperanza/Hope Bay (January 2005 and 25 de Mayo/King George Island (October 2008. On both occasionsa pair of specimens with winter plumage was observed.

The Antarctic permafrost as a testbed for REMS (Rover Environmental Monitoring Station-Mars Science Laboratory)

Science.gov (United States)

Esteban, B.; Ramos, M.; Sebastián, E.; Armiens, C.; Gómez-Elvira, J.; Cabos, W.; de Pablo, M. A.

2009-04-01

The present climatic characteristics of Mars favor the presence of extense permafrost areas in this lonely planet. Therefore environmental parameters that are included in Martian Rover missions are also used for monitoring thermal soil surface evolution in order to study the permafrost active layer thickness and the energy balance in the soil-atmosphere boundary limit layer. The REMS (Rover Environmental Monitoring Station) is an environmental station designed by the Centro de Astrobiología (CAB- Spain) with the collaboration of national and international partners (CRISA/EADS, UPC and FMI), which is part of the payload of the MSL (Mars Science Laboratory) NASA mission to Mars (http://mars.jpl.nasa.gov/msl/overview/). This mission is expected to be launched in the final months of 2009, and mainly consists of a Rover, with a complete set of scientific instruments; the Rover will carry the biggest, most advanced suite of instruments for scientific studies ever sent to the Martian surface. Five sensors compose the REMS instrument: ground (GT-REMS) and air temperatures, wind speed and direction, pressure, humidity and ultraviolet radiation (UV-REMS). A simplified setup of the REMS was deployed on Antarctica in the surroundings of the Spanish Antarctic Stations on Livingston and Deception Islands (Maritime Antarctica), where the permafrost distribution is well-known. The aim of the experiment was to check REMS's sensors response against hard environmental conditions and calibrates their measures with standard Antarctic devices. The experimental apparatuses included some standard meteorological and thermopiles sensors corresponding to the REMS. All the sensors are mounted in a 1.8 m mast and include a Pt100 air temperature sensor with shield solar protection on the mast top, a Kipp and Zonnen CNR1 net radiometer for measuring infrared (5-50 μm) and short wave solar (305-2800 nm) radiation at 1.5 m high, GT-REMS sensor and its amplification box at 0.7 m high and finally

Antibiotic resistance in Escherichia coli strains isolated from Antarctic bird feces, water from inside a wastewater treatment plant, and seawater samples collected in the Antarctic Treaty area

Science.gov (United States)

Rabbia, Virginia; Bello-Toledo, Helia; Jiménez, Sebastián; Quezada, Mario; Domínguez, Mariana; Vergara, Luis; Gómez-Fuentes, Claudio; Calisto-Ulloa, Nancy; González-Acuña, Daniel; López, Juana; González-Rocha, Gerardo

2016-06-01

Antibiotic resistance is a problem of global concern and is frequently associated with human activity. Studying antibiotic resistance in bacteria isolated from pristine environments, such as Antarctica, extends our understanding of these fragile ecosystems. Escherichia coli strains, important fecal indicator bacteria, were isolated on the Fildes Peninsula (which has the strongest human influence in Antarctica), from seawater, bird droppings, and water samples from inside a local wastewater treatment plant. The strains were subjected to molecular typing with pulsed-field gel electrophoresis to determine their genetic relationships, and tested for antibiotic susceptibility with disk diffusion tests for several antibiotic families: β-lactams, quinolones, aminoglycosides, tetracyclines, phenicols, and trimethoprim-sulfonamide. The highest E. coli count in seawater samples was 2400 cfu/100 mL. Only strains isolated from seawater and the wastewater treatment plant showed any genetic relatedness between groups. Strains of both these groups were resistant to β-lactams, aminoglycosides, tetracycline, and trimethoprim-sulfonamide.In contrast, strains from bird feces were susceptible to all the antibiotics tested. We conclude that naturally occurring antibiotic resistance in E. coli strains isolated from Antarctic bird feces is rare and the bacterial antibiotic resistance found in seawater is probably associated with discharged treated wastewater originating from Fildes Peninsula treatment plants.

Circum-Antarctic Shoreward Heat Transport Derived From an Eddy- and Tide-Resolving Simulation

Science.gov (United States)

Stewart, Andrew L.; Klocker, Andreas; Menemenlis, Dimitris

2018-01-01

Almost all heat reaching the bases of Antarctica's ice shelves originates from warm Circumpolar Deep Water in the open Southern Ocean. This study quantifies the roles of mean and transient flows in transporting heat across almost the entire Antarctic continental slope and shelf using an ocean/sea ice model run at eddy- and tide-resolving (1/48°) horizontal resolution. Heat transfer by transient flows is approximately attributed to eddies and tides via a decomposition into time scales shorter than and longer than 1 day, respectively. It is shown that eddies transfer heat across the continental slope (ocean depths greater than 1,500 m), but tides produce a stronger shoreward heat flux across the shelf break (ocean depths between 500 m and 1,000 m). However, the tidal heat fluxes are approximately compensated by mean flows, leaving the eddy heat flux to balance the net shoreward heat transport. The eddy-driven cross-slope overturning circulation is too weak to account for the eddy heat flux. This suggests that isopycnal eddy stirring is the principal mechanism of shoreward heat transport around Antarctica, though likely modulated by tides and surface forcing.

On the Size of the Antarctic Ozone Hole

Science.gov (United States)

Newman, Paul A.; Nash, Eric R.; Kawa, S. Randolph

2002-01-01

The Antarctic ozone hole is a region of extremely large ozone depletion that is roughly centered over the South Pole. Since 1979, the area coverage of the ozone hole has grown from near zero size to over 24 Million sq km. In the 8-year period from 1981 to 1989, the area expanded by 18 Million sq km. During the last 5 years, the hole has been observed to exceed 25 Million sq km over brief periods. In the spring of 2002, the size of the ozone hole barely reached 20 Million sq km for only a couple of days. We will review these size observations, the size trends, and the interannual variability of the size. The area is derived from the area enclosed by the 220 DU total ozone contour. We will discuss the rationale for the choice of 220 DU: 1) it is located near the steep gradient between southern mid-latitudes and the polar region, and 2) 220 DU is a value that is lower than the pre-1979 ozone observations over Antarctica during the spring period. The phenomenal growth of the ozone hole was directly caused by the increases of chlorine and bromine compounds in the stratosphere. In this talk, we will show the relationship of the ozone hole's size to the interannual variability of Antarctic spring temperatures. In addition, we will show the relationship of these same temperatures to planetary-scale wave forcings.

A Record of Holocene Paleoclimate Evolution from Robertson Bay, Victoria Land, Antarctica

Science.gov (United States)

Riesselman, C. R.; Truax, O.; Wilson, G. S.; Parker, R. L.; Yoo, K. C.; Lee, J. I.; Levy, R. H.; Mckay, R. M.

2017-12-01

Regionally representative records of how Antarctica responded to the transition from the Last Glacial Maximum into the Holocene are an essential component of understanding the processes by which the Antarctic cryosphere responds to a changing climate. Here, we present a high-resolution record of Holocene Antarctic paleoclimate evolution from a previously unstudied section of the Victoria Land margin. In 2015 the Korea Polar Research Institute collected a 571 cm sediment core, GC57, from Robertson Bay, a protected embayment west of Cape Adare and adjacent to the outlet glaciers of the Transantarctic Mountains. Using diatom assemblages, bulk sediment geochemistry, and the magnetic properties of GC57, we aim to reconstruct the response of the East Antarctic Ice Sheet to warming associated with deglaciation and the Holocene climatic optima at the interface between the Ross Sea and the Southern Ocean. Our multiproxy approach allows us to study sea ice extent, seasonality, ocean stratification and circulation, and primary productivity from the mid-Holocene (7,400 14C year BP) to the present. A sea-ice associated diatom assemblage indicative of summer sea surface temperatures below 0˚C dominates the basal section of GC57. Although diatoms are well preserved, the unit is characterized by low wt% biogenic silica (average 9%) and a high concentration of magnetic minerals, indicating that biogenic production persisted despite substantial terrigenous input into the bay. A rapid transition at 4708 14C yr BP is identified by a steep increase in wt% BSi (average 13%), a decrease in magnetic minerals, and a subtle assemblage change towards sea-ice associated diatoms with slightly warmer temperature tolerances. The novel ramped pyrolosis 14C dating methodology allows us to date the carbon fixed concurrent with deposition and generate a robust age model for GC57 with an accuracy previously difficult to achieve given the uncertainties associated with dating bulk acid insoluble

Neutron activation analysis on sediments from Victoria Land, Antarctica. Multi-elemental characterization of potential atmospheric dust sources

International Nuclear Information System (INIS)

Baccolo, G.; Maggi, V.; Baroni, C.; Clemenza, M.; Motta, A.; Nastasi, M.; Previtali, E.; University of Milano-Bicocca, Milan; Delmonte, B.; Salvatore, M.C.

2014-01-01

The elemental composition of 40 samples of mineral sediments collected in Victoria Land, Antarctica, in correspondence of ice-free sites, is presented. Concentration of 36 elements was determined by instrumental neutron activation analysis, INAA. The selection of 6 standard reference materials and the development of a specific analytical procedure allowed to reduce measurements uncertainties and to verify the reproducibility of the results. The decision to analyze sediment samples from Victoria Land ice-free areas is related to recent investigations regarding mineral dust content in the TALos Dome ICE core (159deg11'E; 72deg49'S, East Antarctica, Victoria Land), in which a coarse local fraction of dust was recognized. The characterization of Antarctic potential source areas of atmospheric mineral dust is the first step to identify the active sources of dust for the Talos Dome area and to reconstruct the atmospheric pathways followed by air masses in this region during different climatic periods. Principal components analysis was used to identify elements and samples correlations; attention was paid specially to rare earth elements (REE) and incompatible/compatible elements (ICE) in respect to iron, which proved to be the most discriminating elemental groups. The analysis of REE and ICE concentration profiles supported evidences of chemical weathering in ice-free areas of Victoria Land, whereas cold and dry climate conditions of the Talos Dome area and in general of East Antarctica. (author)

Annually resolved southern hemisphere volcanic history from two Antarctic ice cores

Science.gov (United States)

Cole-Dai, Jihong; Mosley-Thompson, Ellen; Thompson, Lonnie G.

1997-07-01

The continuous sulfate analysis of two Antarctic ice cores, one from the Antarctic Peninsula region and one from West Antarctica, provides an annually resolved proxy history of southern semisphere volcanism since early in the 15th century. The dating is accurate within ±3 years due to the high rate of snow accumulation at both core sites and the small sample sizes used for analysis. The two sulfate records are consistent with each other. A systematic and objective method of separating outstanding sulfate events from the background sulfate flux is proposed and used to identify all volcanic signals. The resulting volcanic chronology covering 1417-1989 A.D. resolves temporal ambiguities about several recently discovered events. A number of previously unknown, moderate eruptions during late 1600s are uncovered in this chronology. The eruption of Tambora (1815) and the recently discovered eruption of Kuwae (1453) in the tropical South Pacific injected the greatest amount of sulfur dioxide into the southern hemisphere stratosphere during the last half millennium. A technique for comparing the magnitude of volcanic events preserved within different ice cores is developed using normalized sulfate flux. For the same eruptions the variability of the volcanic sulfate flux between the cores is within ±20% of the sulfate flux from the Tambora eruption.

Functional ecology of an Antarctic Dry Valley

Science.gov (United States)

Chan, Yuki; Van Nostrand, Joy D.; Zhou, Jizhong; Pointing, Stephen B.

2013-01-01

The McMurdo Dry Valleys are the largest ice-free region in Antarctica and are critically at risk from climate change. The terrestrial landscape is dominated by oligotrophic mineral soils and extensive exposed rocky surfaces where biota are largely restricted to microbial communities, although their ability to perform the majority of geobiological processes has remained largely uncharacterized. Here, we identified functional traits that drive microbial survival and community assembly, using a metagenomic approach with GeoChip-based functional gene arrays to establish metabolic capabilities in communities inhabiting soil and rock surface niches in McKelvey Valley. Major pathways in primary metabolism were identified, indicating significant plasticity in autotrophic, heterotrophic, and diazotrophic strategies supporting microbial communities. This represents a major advance beyond biodiversity surveys in that we have now identified how putative functional ecology drives microbial community assembly. Significant differences were apparent between open soil, hypolithic, chasmoendolithic, and cryptoendolithic communities. A suite of previously unappreciated Antarctic microbial stress response pathways, thermal, osmotic, and nutrient limitation responses were identified and related to environmental stressors, offering tangible clues to the mechanisms behind the enduring success of microorganisms in this seemingly inhospitable terrain. Rocky substrates exposed to larger fluctuations in environmental stress supported greater functional diversity in stress-response pathways than soils. Soils comprised a unique reservoir of genes involved in transformation of organic hydrocarbons and lignin-like degradative pathways. This has major implications for the evolutionary origin of the organisms, turnover of recalcitrant substrates in Antarctic soils, and predicting future responses to anthropogenic pollution. PMID:23671121

Polychaeta Orbiniidae from Antarctica, the Southern Ocean, the Abyssal Pacific Ocean, and off South America.

Science.gov (United States)

Blake, James A

2017-01-12

The orbiniid polychaetes chiefly from Antarctic and subantarctic seas and off South America are described based on collections of the National Museum of Natural History and new material from surveys conducted by the United States Antarctic Program and other federal and privately funded sources as well as participation in international programs. A total of 44 species of Orbiniidae distributed in 10 genera are reported from the Pacific Ocean and waters off South America and Antarctica. Twenty-one species are new to science; one species is renamed. Berkeleyia heroae n. sp., B. abyssala n. sp., B. weddellia n. sp.; B. hadala n. sp., Leitoscoloplos simplex n. sp., L. plataensis n. sp., L. nasus n. sp., L. eltaninae n. sp., L. phyllobranchus n. sp., L. rankini n. sp., Scoloplos bathytatus n. sp., S. suroestense n. sp., Leodamas hyphalos n. sp., L. maciolekae n. sp., L. perissobranchiatus n. sp., Califia bilamellata n. sp., Orbinia orensanzi n. sp., Naineris antarctica n. sp., N. argentiniensis n. sp., Orbiniella spinosa n. sp., and O. landrumae n. sp. are new to science. A new name, Naineris furcillata, replaces N. chilensis Carrasco, 1977, a junior homonym of N. dendtritica chilensis Hartmann‑Schröder, 1965, which is raised to full species status. Leodamas cochleatus (Ehlers, 1900) is removed from synonymy and redescribed. A neotype is established for Leodamas verax Kinberg, 1966, the type species. A general overview of Leodamas species is provided. The Leitoscoloplos kerguelensis (McIntosh, 1885) complex is reviewed and partially revised. Definitions of the genera of the Orbiniidae are updated to conform to recently described taxa. Several new synonymies are proposed following a reexamination of previously described type specimens. The morphological characters used to identify and classify orbiniids are reviewed. The biogeographic and bathymetric distributions of the South American and Southern Ocean orbiniid fauna are reviewed.

An Ensemble Analysis of Antarctic Glacial Isostatic Adjustment and Sea Level

Science.gov (United States)

Lecavalier, B.; Tarasov, L.

2016-12-01

Inferences of past ice sheet evolution that lack any uncertainty assessment (implicit or explicit), have little value. A developing technique for explicit uncertainty quantification of glacial systems is Bayesian calibration of models against large observational data-sets (Tarasov et al., 2012). The foundation for a Bayesian calibration of a 3D glacial systems model (GSM) for Antarctica has recently been completed (Briggs et al., 2013; 2014; Briggs and Tarasov, 2013). Bayesian calibration thoroughly samples model uncertainties against fits to observational data to generate a probability distribution for the Antarctic Ice Sheet deglaciation with explicit and well-defined confidence intervals. To have validity as a complete inference of past ice sheet evolution, Bayesian calibration requires a model that "brackets reality".Past work has shown the GSM to have likely inadequate range of grounding line migration in certain sectors as well as persistent ice thickness biases in topographically complex regions (Briggs et al., 2014). To advance towards full calibration, these deficiencies are being addressed through a number of model developments. The grounding line scheme has been revised (Pollard and DeConto, 2012), the horizontal resolution is increased to 20 km, and boundary conditions are updated. The basal drag representation now includes the sub-grid treatment of the thermo-mechanical impacts of high basal roughness. Parametric uncertainties in basal drag for regions that are presently marine have been re-evaluated. The impact of past changes in ocean temperature on sub ice shelf melt is explicitly incorporated in the current ocean forcing parametric scheme. Uncertainties in earth rheology are also probed to robustly quantify uncertainties affiliated with glacial isostatic adjustment. The ensemble analysis of the Antarctic glacial system provides dynamical bounds on past and present Antarctica glacial isostatic adjustment and sea level contributions. This research

Antarctic sea ice increase consistent with intrinsic variability of the Amundsen Sea Low

Science.gov (United States)

Turner, John; Hosking, J. Scott; Marshall, Gareth J.; Phillips, Tony; Bracegirdle, Thomas J.

2016-04-01

We investigate the relationship between atmospheric circulation variability and the recent trends in Antarctic sea ice extent (SIE) using Coupled Model Intercomparison Project Phase 5 (CMIP5) atmospheric data, ECMWF Interim reanalysis fields and passive microwave satellite data processed with the Bootstrap version 2 algorithm. Over 1979-2013 the annual mean total Antarctic SIE increased at a rate of 195 × 103 km2 dec-1 (1.6 % dec-1), p 4.0 % dec-1) has been in the Ross Sea sector. Off West Antarctica there is a high correlation between trends in SIE and trends in the near-surface winds. The Ross Sea SIE seasonal trends are positive throughout the year, but largest in spring. The stronger meridional flow over the Ross Sea has been driven by a deepening of the Amundsen Sea Low (ASL). Pre-industrial control and historical simulations from CMIP5 indicate that the observed deepening of the ASL and stronger southerly flow over the Ross Sea are within the bounds of modeled intrinsic variability. The spring trend would need to continue for another 11 years for it to fall outside the 2 standard deviation range seen in 90 % of the simulations.

Seasonal trophic ecology of the dominant Antarctic coral Malacobelemnon daytoni (Octocorallia, Pennatulacea, Kophobelemnidae).

Science.gov (United States)

Servetto, N; Rossi, S; Fuentes, V; Alurralde, G; Lagger, C; Sahade, R

2017-09-01

Antarctic ecosystems present highly marked seasonal patterns in energy input, which in turn determines the biology and ecology of marine invertebrate species. This relationship is stronger at lower levels of the food web, while upper levels may be less dependent on primary production pulses. The pennatulid Malacobelemnon daytoni, is one of the most abundant species in Potter Cove, Antarctica. In order to assess its trophic ecology and energetic strategies, its biochemical (carbohydrates, proteins and lipids), Fatty Acid (FA) and Stable Isotope (SI) (δ 15 N and δ 13 C) compositions were studied over a year-round period. The FA and SI profiles suggest an omnivorous diet and opportunistic feeding strategy for the species. These results, together with biochemical analysis (higher lipid and carbohydrate concentration observed in July and October 2009), support the hypothesis that resuspension events may be an important source of energy, reducing the seasonality of food depletion periods in winter. The evidence presented here gives us a better insight into the success that this species has in Potter Cove and under the current environmental changes experienced by the Antarctic Peninsula. Copyright © 2017 Elsevier Ltd. All rights reserved.

Phosphatase activity in Antarctica soil samples as a biosignature of extant life

Science.gov (United States)

Sato, Shuji; Itoh, Yuki; Takano, Yoshinori; Fukui, Manabu; Kaneko, Takeo; Kobayashi, Kensei

Microbial activities have been detected in such extreme terrestrial environments as deep lithosphere, a submarine hydrothermal systems, stratosphere, and Antarctica. Microorganisms have adapted to such harsh environments by evolving their biomolecules. Some of these biomolecules such as enzymes might have different characteristics from those of organisms in ordinary environments. Many biosignatures (or biomarkers) have been proposed to detect microbial activities in such extreme environments. A number of techniques are proposed to evaluate biological activities in extreme environments including cultivation methods, assay of metabolism, and analysis of bioorganic compounds like amino acids and DNA. Enzyme activities are useful signature of extant life in extreme environments. Among many enzymes, phosphatase could be a good indicator of biological activities, since phosphate esters are essential for all the living terrestrial organisms. In addition, alkaline phosphatase is known as a typical zinc-containing metalloenzyme and quite stable in environments. We analyzed phosphatase activities in Antarctica soil samples to see whether they can be used as biosignatures for extant life. In addition, we characterized phosphatases extracted from the Antarctica soil samples, and compared with those obtained from other types of environments. Antarctica surface environments are quite severe environments for life since it is extremely cold and dry and exposed to strong UV and cosmic rays. We tried to evaluate biological activities in Antarctica by measuring phosphatase activities. Surface soil samples are obtained at the Sites 1-8 near Showa Base in Antarctica during the 47th Japan Antarctic exploration mission in 2005-6. Activities of acid phosphatase (ACP) and alkaline phosphatase (ALP) are measured spectrophotometrically after mixing the powdered sample and p-nitrophenyl phosphate solution (pH 6.5 for ACP, pH 8.0 for ALP). ALP was characterized after extraction from soils with

Spectral Discrimination of Vegetation Classes in Ice-Free Areas of Antarctica

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María Calviño-Cancela

2016-10-01

Full Text Available Detailed monitoring of vegetation changes in ice-free areas of Antarctica is crucial to determine the effects of climate warming and increasing human presence in this vulnerable ecosystem. Remote sensing techniques are especially suitable in this distant and rough environment, with high spectral and spatial resolutions needed owing to the patchiness and similarity between vegetation elements. We analyze the reflectance spectra of the most representative vegetation elements in ice-free areas of Antarctica to assess the potential for discrimination. This research is aimed as a basis for future aircraft/satellite research for long-term vegetation monitoring. The study was conducted in the Barton Peninsula, King George Island. The reflectance of ground patches of different types of vegetation or bare ground (c. 0.25 m 2 , n = 30 patches per class was recorded with a spectrophotometer measuring between 340 nm to 1025 nm at a resolution of 0.38 n m . We used Linear Discriminant Analysis (LDA to classify the cover classes according to reflectance spectra, after reduction of the number of bands using Principal Component Analysis (PCA. The first five principal components explained an accumulated 99.4% of the total variance and were added to the discriminant function. The LDA classification resulted in c. 92% of cases correctly classified (a hit ratio 11.9 times greater than chance. The most important region for discrimination was the visible and near ultraviolet (UV, with the relative importance of spectral bands steeply decreasing in the Near Infra-Red (NIR region. Our study shows the feasibility of discriminating among representative taxa of Antarctic vegetation using their spectral patterns in the near UV, visible and NIR. The results are encouraging for hyperspectral vegetation mapping in Antarctica, which could greatly facilitate monitoring vegetation changes in response to a changing environment, reducing the costs and environmental impacts of

Aerosols in King George Island (Antarctic peninsula) using PIXE and alpha spectrometry

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Dias da Cunha, K.; Medeiros, G.; Leal, M.A.; Lima, C.; Dalia, K.C.

2009-01-01

The aim of this study was to characterize the airborne particles and particles deposited in the recent snow samples collected at King George Island (Admiralty Bay) in order to evaluate the possible local sources of airborne particles and the aerosol transport from South America to Antarctic at sea level. Airborne particles samples were collected using a cascade impactor and cyclones at several sampling points at Admiralty Bay. Airborne particles were also collected during the ship travel from Rio de Janeiro to Antarctica. The recent snow samples and aerosols collected at several sampling points at Admiralty Bay were analyzed by PIXE for the determination of the elemental mass concentration. Snow samples were analyzed by alpha spectrometry to determine the 232Th, 228Th, 238U and 234U concentrations in snow. The Mass Median Aerodynamic Diameter of airborne particles was determined. The results suggest that there is a correlation between the aerosol samples and the particles deposited in the snow, but the elemental mass distributions are not equal. The snow elemental concentration can be used as an indicator of the elements present in the aerosols. The local aerosol sources (natural and anthropogenic) have been considered to characterize the aerosol transport to Antarctic, mainly King George Island. The main aerosol sources are the marine spray, weathering of local rocks and anthropogenic sources, as the diesel burning in the island. Besides the local aerosol sources the transport of airborne particles from south Atlantic to Antarctic is an important source of airborne particles at King George Island. (author)

Seasonal variations and vertical features of aerosol particles in the Antarctic troposphere

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K. Hara

2011-06-01

Full Text Available Tethered balloon-borne aerosol measurements were conducted at Syowa Station, Antarctica during the 46th Japanese Antarctic expedition (2005–2006. The CN concentration reached a maximum in the summer, although the number concentrations of fine particles (D_p>0.3 μm and coarse particles (D_p>2.0 μm increased during the winter–spring. The CN concentration was 30–2200 cm⁻³ near the surface (surface – 500 m and 7–7250 cm⁻³ in the lower free troposphere (>1500 m. During the austral summer, higher CN concentration was often observed in the lower free troposphere, where the number concentrations in fine and coarse modes were remarkably lower. The frequent appearance of higher CN concentrations in the free troposphere relative to continuous aerosol measurements at the ground strongly suggests that new particle formation is more likely to occur in the lower free troposphere in Antarctic regions. Seasonal variations of size distribution of fine-coarse particles show that the contribution of the coarse mode was greater in the winter–spring than in summer because of the dominance of sea-salt particles in the winter–spring. The number concentrations of fine and coarse particles were high in air masses from the ocean and mid-latitudes. Particularly, aerosol enhancement was observed not only in the boundary layer, but also in the lower free troposphere during and immediately after Antarctic haze events occurring in May, July and September.

Novel flame retardants (N-FRs), polybrominated diphenyl ethers (PBDEs) and dioxin-like polychlorinated biphenyls (DL-PCBs) in fish, penguin, and skua from King George Island, Antarctica.

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Wolschke, Hendrik; Meng, Xiang-Zhou; Xie, Zhiyong; Ebinghaus, Ralf; Cai, Minghong

2015-07-15

Persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), are frequently detected in biota from Antarctica, whereas no data are available for their replacements, such as novel flame retardants (N-FRs). This study presented the occurrence of several N-FRs, PBDEs, and PCBs in tissue samples of an Antarctic rock cod (Trematomus bernacchii), a young gentoo penguin (Pygoscelis papua), and a brown skua (Stercorarius antarcticus) collected from King George Island. The total concentrations of N-FRs (ΣN-FRs; mean: 931 pg/g dry weight (dw)) were comparable to PBDEs (Σ8PBDEs; 681 pg/gdw), which were much lower than PCBs (ΣDL-PCBs; 12,800 pg/gdw). Overall, skua contained two to three orders of magnitude higher contamination than penguin and fish. In the future, more attention should be focused on the fate of N-FRs in Antarctica, where usages have increased since PBDEs were banned. To our knowledge, this is the first report of N-FRs in biota from Antarctica. Copyright © 2015. Published by Elsevier Ltd.

Combined ice core and climate-model evidence for the collapse of the West Antarctic Ice Sheet during Marine Isotope Stage 5e.

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Steig, Eric J.; Huybers, Kathleen; Singh, Hansi A.; Steiger, Nathan J.; Frierson, Dargan M. W.; Popp, Trevor; White, James W. C.

2015-04-01

It has been speculated that collapse of the West Antarctic Ice Sheet explains the very high eustatic sea level rise during the last interglacial period, marine isotope stage (MIS) 5e, but the evidence remains equivocal. Changes in atmospheric circulation resulting from a collapse of the West Antarctic Ice Sheet (WAIS) would have significant regional impacts that should be detectable in ice core records. We conducted simulations using general circulation models (GCMs) at varying levels of complexity: a gray-radiation aquaplanet moist GCM (GRaM), the slab ocean version of GFDL-AM2 (also as an aquaplanet), and the fully-coupled version of NCAR's CESM with realistic topography. In all the experiments, decreased elevation from the removal of the WAIS leads to greater cyclonic circulation over the West Antarctic region. This creates increased advection of relatively warm marine air from the Amundsen-Bellingshausen Seas towards the South Pole, and increased cold-air advection from the East Antarctic plateau towards the Ross Sea and coastal Marie Byrd Land. The result is anomalous warming in some areas of the East Antarctic interior, and significant cooling in Marie Byrd Land. Comparison of ice core records shows good agreement with the model predictions. In particular, isotope-paleotemperature records from ice cores in East Antarctica warmed more between the previous glacial period (MIS 6) and MIS 5e than coastal Marie Byrd Land. These results add substantial support to other evidence for WAIS collapse during the last interglacial period.