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Sample records for antarctic dry valley

  1. Functional ecology of an Antarctic Dry Valley

    OpenAIRE

    Chan, Yuki; Joy D Van Nostrand; Zhou, Jizhong; Pointing, Stephen B.; Farrell, Roberta L.

    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 ...

  2. Testing a Mars science outpost in the Antarctic dry valleys

    Science.gov (United States)

    Andersen, D. T.; Mckay, C. P.; Wharton, R. A.; Rummel, J. D.

    1992-01-01

    Field research conducted in the Antarctic has been providing insights about the nature of Mars in the science disciplines of exobiology and geology. Located in the McMurdo Dry Valleys of southern Victoria Land (160 deg and 164 deg E longitude and 76 deg 30 min and 78 deg 30 min S latitude), research outposts are inhabited by teams of 4-6 scientists. It is proposed that the design of these outposts be expanded to enable meaningful tests of many of the systems that will be needed for the successful conduct of exploration activities on Mars. Although there are some important differences between the environment in the Antarctic dry valleys and on Mars, the many similarities and particularly the field science activities, make the dry valleys a useful terrestrial analog to conditions on Mars. Three areas have been identified for testing at a small science outpost in the dry valleys: (1) studying human factors and physiology in an isolated environment; (2) testing emerging technologies (e.g. innovative power management systems, advanced life support facilities including partial bioregenerative life support systems for water recycling and food growth, telerobotics, etc.); and (3) conducting basic scientific research that will enhance understanding of Mars while contributing to the planning for human exploration. It is suggested that an important early result of a Mars habitat program will be the experience gained by interfacing humans and their supporting technology in a remote and stressful environment.

  3. Spatial modelling of wetness for the Antarctic Dry Valleys

    Directory of Open Access Journals (Sweden)

    Glen Stichbury

    2011-03-01

    Full Text Available This paper describes a method used to model relative wetness for part of the Antarctic Dry Valleys using Geographic Information Systems (GIS and remote sensing. The model produces a relative index of liquid water availability using variables that influence the volume and distribution of water. Remote sensing using Moderate Resolution Imaging Spectroradiometer (MODIS images collected over four years is used to calculate an average index of snow cover and this is combined with other water sources such as glaciers and lakes. This water source model is then used to weight a hydrological flow accumulation model that uses slope derived from Light Detection and Ranging (LIDAR elevation data. The resulting wetness index is validated using three-dimensional visualization and a comparison with a high-resolution Advanced Land Observing Satellite image that shows drainage channels. This research demonstrates that it is possible to produce a wetness model of Antarctica using data that are becoming widely available.

  4. Antarctic Dry Valley Streams and Lakes: Analogs for Noachian Mars?

    Science.gov (United States)

    Head, James; Marchant, David

    2013-04-01

    Recent climate models suggest that Noachian Mars may have been characterized by a "cold and icy", rather than a "warm and wet" climate. Noachian valley networks and open basin lakes have been cited as key evidence for a "warm and wet" early Mars. We investigate fluvial and lacustrine processes in the Mars-like Antarctic McMurdo Dry Valleys (MDV) to assess whether such processes, which take place in the absence of pluvial activity and with mean annual temperatues (MAT) well below zero, can serve as informative proxies for Noachian Mars. In contrast to temperate climates, fluvial processes in the MDV (and thus a host of weathering, erosion and transport processes there) are severely limited by the lack of rainfall. The limited sources of meltwater provide very local streams and hyporheic zones, serving to concentrate chemical weathering processes and biological ecosystems. The horizontally stratified hydrologic system means that localized meltwater is constrained to flow in a very shallow and narrow aquifer perched on top of the ice table aquiclude. Lakes and ponds in temperate areas are largely of pluvial origin and characterized by abundant vegetation, large drainage basins and higher order streams delivering rainwater. In contrast, the hyperarid, hypothermal conditions in the MDV mean that there is no rainfall, water sources are limited primarily to meltwater from the surface of cold-based glaciers, and drainage into lakes is seasonal and highly variable, being related to changing and sluggish response to surface ice hypsometry, itself a function of changing climate. Lake surface fluctuations are caused by imbalances between meltwater input and sublimation from the lake surface ice and this sensitive balance tends to magnify even minor climate signals. Where does the lakewater come from and under what conditions is excess meltwater produced to cause modifications in their levels? The dominant means of supply (meltwater) and loss (ablation) are clearly seasonally

  5. Resource Limitations on Soil Microbial Activity in an Antarctic Dry Valley

    DEFF Research Database (Denmark)

    Sparrow, Asley; Gregorich, Ed; Hopkins, David; Novis, P; Elberling, Bo; Greenfield, L.G.

    2011-01-01

    Although Antarctic dry valley soils function under some of the harshest environmental conditions on the planet, there is significant biological activity concentrated in small areas in the landscape. These productive areas serve as a source of C and N in organic matter redistributed to the......, when that constraint is alleviated, the organisms are able to access a pool of stored C that they could not metabolize before. The effects of added C and N substrates on respiration rates under laboratory conditions were more rapid and significant than the response rates measured in situ. Because the...

  6. Microbial ecology of extreme environments: Antarctic dry valley yeasts and growth in substrate limited habitats

    Science.gov (United States)

    Vishniac, H. S.

    1981-01-01

    The multiple stresses temperature, moisture, and for chemoheterotrophs, sources of carbon and energy of the Dry Valley Antarctica soils allow at best depauperate communities, low in species diversity and population density. The nature of community structure, the operation of biogeochemical cycles, the evolution and mechanisms of adaptation to this habitat are of interest in informing speculations upon life on other planets as well as in modeling the limits of gene life. Yeasts of the Cryptococcus vishniacil complex (Basidiobiastomycetes) are investigated, as the only known indigenes of the most hostile, lichen free, parts of the Dry Valleys. Methods were developed for isolating these yeasts (methods which do not exclude the recovery of other microbiota). The definition of the complex was refined and the importance of nitrogen sources was established as well as substrate competition in fitness to the Dry Valley habitats.

  7. Granitoids of the Dry Valleys area, southern Victoria Land : geochemistry and evolution along the early Paleozoic Antarctic Craton margin

    International Nuclear Information System (INIS)

    Field relationships and geochemistry indicate granitoid plutons of the Dry Valleys area comprise at least three petrogenetically distinct suites. The older Dry Valleys 1a (DV1a) suite, comprising the Bonney, Catspaw, Denton, Cavendish, and Wheeler Plutons and hornblende-biotite orthogneisses, and Dry Valleys 1b (DV1b) suite, comprising the Hedley, Valhalla, St Johns, Dun, Calkin, and Suess Plutons, biotite granitoid dikes and biotite orthogneisses, were emplaced before prominent swarms of Vanda mafic and felsic dikes. Both the DV1a and DV1b suites are time transgressive, with older intrusions in each suite being emplaced during the later stages of deformation of the Koettlitz Group. Younger granitoids that postdate the majority of the Vanda dikes include: the Dry Valleys 2 (DV2) suite, comprising the Pearse and Nibelungen Plutons plus several smaller, unnamed plugs; and the Harker, Swinford, Orestes, and Brownworth Plutons with identical field relationships and enclaves but distinct chemistries. Chemical characteristics and limited Rb-Sr isotopic dating indicate plutonism before c. 500 Ma was dominated by the Cordilleran I-type DV1a suite, inferred to have developed during melting above a west-dipping subduction zone along the Antarctic Craton margin. The chemical characteristics of the DV1b suite indicate large-scale melting of a quartzo-feldspathic protolith lacking residual plagioclase, but containing refractory garnet. Potential DV1b suite source rocks include metamorphosed immature sediments, possibly underplated along the subduction zone associated with DV1a magmatism, or older granitoid orthogneisses. Major DV1b plutonism at 490 Ma marks the end of subduction-related plutonism in southern Victoria Land. Younger DV2 alkali-calcic, Caledonian I-type plutonism is inferred to have formed in response to uplift and extension between 480 and 455 Ma. Lack of DV2 suite correlatives and Vanda mafic and felsic dikes in northern Victoria Land suggests significantly

  8. Microbial responses to carbon and nitrogen supplementation in an Antarctic dry valley soil

    DEFF Research Database (Denmark)

    Dennis, P. G.; Sparrow, A. D.; Gregorich, E. G.;

    2013-01-01

    organic carbon concentration, indicating efficient conversion of soil organic carbon into microbial biomass and rapid turnover of soil organic carbon. The ELFA concentrations increased significantly in response to carbon additions, indicating that carbon supply was the main constraint to microbial...... activity. The large ELFA concentrations relative to soil organic carbon and the increases in ELFA response to organic carbon addition are both interpreted as evidence for the soil microbial community containing organisms with efficient scavenging mechanisms for carbon. The diversity of the ELFA profiles......The soils of the McMurdo Dry Valleys are exposed to extremely dry and cold conditions. Nevertheless, they contain active biological communities that contribute to the biogeochemical processes. We have used ester-linked fatty acid (ELFA) analysis to investigate the effects of additions of carbon and...

  9. Phosphatase Activities of Endolithic Communities in Rocks of the Antarctic Dry Valleys.

    Science.gov (United States)

    Banerjee; Whitton; Wynn-Williams

    2000-01-01

    Phosphorus is scarce in Beacon Sandstone of the McMurdo Dry Valleys, Antarctica, and any input from precipitation is minimal. In endolithic microbial communities recycling of P by the action of phosphatases may therefore be important. The phosphatase activities of three different types of endolithic communities in the McMurdo Dry Valley, Antarctica, were studied in the laboratory. The dominant phototrophs were Chroococcidiopsis, mixed Gloeocapsa and Trebouxia, and Trebouxia. Bacteria were also visually conspicuous in the latter two communities, and the Trebouxia in both cases formed a lichenized association with fungal hyphae. In each case marked phosphomonoesterase (PMEase) activity was found in assays with 4-methylumbelliferyl phosphate (MUP) or p-nitrophenyl phosphate as substrate, and phosphodiesterase activity with bis-p-nitrophenyl phosphate as substrate. The pH optimum of PMEase (assayed at 0.5 pH intervals) of the Chroococcidiopsis, Gloeocapsa-Trebouxia, and Trebouxia communities was 9.5, 5.5, and 8.0, respectively. These values are similar for aqueous extracts of the respective rocks (pH 9.2, 6.2, 7.5). All three communities showed significantly higher PMEase activity at 5 degrees than 1 degrees C, and the first two also showed much higher activity at 5 degrees than 10 degrees C. All three communities also showed slightly lower activity in the light (7 µmol photon m(-2) s(-1)) than the dark; this was found with all substrates and substrate concentrations. Prior exposure of a moistened sample to light for 2 h led to a reduction in activity even when the subsequent assay was done in the dark. The rate of PMEase activity (using 100 µM MUP) in the Gloeocapsa-Trebouxia and Trebouxia communities was approximately linear with time up to 24 h, whereas the Chroococcidiopsis community showed a marked decrease after 6 h. At least part of this was due to retention of the 4-methylumbelliferone (MU) hydrolysis product. In spite of the assays being conducted on a whole

  10. Kilometer-thick ice-sheets in the northern mid-latitudes of Mars in the Amazonian: Analogs from the East Antarctic Ice Sheet and the Dry Valleys

    Science.gov (United States)

    Head, James W.; Marchant, David R.

    2008-09-01

    Introduction. The strong geomorphic similarities between lobate deposits on the northwest flank of the Tharsis Montes [1,2, 12-13] and along the dichotomy boundary between 30° and 50° [3] with terrestrial cold-based glaciers and glacial deposits has led to new hypotheses for geologically recent (Amazonian-age) low and mid-latitude glaciation on Mars [1,4]. A common theme among many of these studies has been to identify individual landscape elements on Mars and match them with terrestrial counterparts from cold polar deserts on Earth [5,6]. Here, we use the documented long-term history of outlet and alpine glaciers along the East Antarctic Ice Sheet in the Dry Valleys of Antarctica as a suitable analog for glaciation along the martian dichotomy boundary. As a guiding principle we note that, just as for terrestrial glacial landsystems, the most recent ice-related deposit/feature along the dichotomy boundary on Mars need not reflect the maximum in ice volume and/or ice configuration. The Antarctic Dry Valleys (ADV). A terrestrial analog for cold-based glaciation across steppedbedrock topography. To a first order, the large-scale bedrock geomorphology of the Antarctic Dry Valleys (Transantarctic mountain rift-margin upwarp) approximates the martian dichotomy boundary: the valleys occur within, and dissect, a series of broad, coast-facing escarpments (total relief of up to 3000 m) separated by isolated inselbergs. In the middle Miocene, sometime between 14.8 and 12.5 Ma [7, 8], all but the highest mountains in the Dry Valleys were overrun by a major expansion of East Antarctic ice. During this time, ice spilled across bedrock escarpments and flowed out across low-lying valleys toward the continental shelf. A modern-day counterpart for the maximum-overriding stage is seen inland of the ADV, where glacier ice still overrides stepped bedrock topography (Fig. 1). Ice expansion was triggered when the Antarctic cryosphere transitioned from relatively warm and wet (fostering

  11. Spring thaw ionic pulses boost nutrient availability and microbial growth in entombed Antarctic Dry Valley cryoconite holes.

    Science.gov (United States)

    Telling, Jon; Anesio, Alexandre M; Tranter, Martyn; Fountain, Andrew G; Nylen, Thomas; Hawkings, Jon; Singh, Virendra B; Kaur, Preeti; Musilova, Michaela; Wadham, Jemma L

    2014-01-01

    The seasonal melting of ice entombed cryoconite holes on McMurdo Dry Valley glaciers provides oases for life in the harsh environmental conditions of the polar desert where surface air temperatures only occasionally exceed 0°C during the Austral summer. Here we follow temporal changes in cryoconite hole biogeochemistry on Canada Glacier from fully frozen conditions through the initial stages of spring thaw toward fully melted holes. The cryoconite holes had a mean isolation age from the glacial drainage system of 3.4 years, with an increasing mass of aqueous nutrients (dissolved organic carbon, total nitrogen, total phosphorus) with longer isolation age. During the initial melt there was a mean nine times enrichment in dissolved chloride relative to mean concentrations of the initial frozen holes indicative of an ionic pulse, with similar mean nine times enrichments in nitrite, ammonium, and dissolved organic matter. Nitrate was enriched twelve times and dissolved organic nitrogen six times, suggesting net nitrification, while lower enrichments for dissolved organic phosphorus and phosphate were consistent with net microbial phosphorus uptake. Rates of bacterial production were significantly elevated during the ionic pulse, likely due to the increased nutrient availability. There was no concomitant increase in photosynthesis rates, with a net depletion of dissolved inorganic carbon suggesting inorganic carbon limitation. Potential nitrogen fixation was detected in fully melted holes where it could be an important source of nitrogen to support microbial growth, but not during the ionic pulse where nitrogen availability was higher. This study demonstrates that ionic pulses significantly alter the timing and magnitude of microbial activity within entombed cryoconite holes, and adds credence to hypotheses that ionic enrichments during freeze-thaw can elevate rates of microbial growth and activity in other icy habitats, such as ice veins and subglacial regelation zones

  12. The ecological dichotomy of ammonia-oxidizing archaea and bacteria in the hyper-arid soils of the Antarctic Dry Valleys

    OpenAIRE

    Magalhães, Catarina M.; Machado, Ana; Frank-Fahle, Béatrice; Lee, Charles K; Cary, S. Craig

    2014-01-01

    The McMurdo Dry Valleys of Antarctica are considered to be one of the most physically and chemically extreme terrestrial environments on the Earth. However, little is known about the organisms involved in nitrogen transformations in these environments. In this study, we investigated the diversity and abundance of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in four McMurdo Dry Valleys with highly variable soil geochemical properties and climatic conditions: Miers Valley, Upper Wright Va...

  13. Characterization of 15 selected coccal bacteria isolated from Antarctic rock and soil samples from the McMurdo-Dry Valleys (South-Victoria Land)

    Science.gov (United States)

    Siebert, J.; Hirsch, P.; Friedmann, E. I. (Principal Investigator)

    1988-01-01

    Approximately 1500 cultures of microorganisms were isolated from rocks and soils of the Ross Desert (McMurdo-Dry Valleys). From these, 15 coccoid strains were chosen for more detailed investigation. They were characterized by morphological, physiological and chemotaxonomical properties. All isolates were Gram-positive, catalase-positive and nonmotile. Six strains showed red pigmentation and could be identified as members of the genera Micrococcus (M. roseus, M. agilis) or Deinococcus. In spite of their coccoid morphology, the remaining nine strains had to be associated with coryneform bacteria (Arthrobacter, Brevibacterium), because of their cell wall composition and G+C ratios. Most of the strains were psychrotrophic, but one strain was even obligately psychrophilic, with a temperature maximum below 20 degrees C. Red cocci had in vitro pH optima above 9.0 although they generally originated from acid samples. Most isolates showed a preference for sugar alcohols and organic acids, compounds which are commonly known to be released by lichens, molds and algae, the other components of the cryptoendolithic ecosystem. These properties indicate that our strains are autochthonous members of the natural Antarctic microbial population.

  14. The ecological dichotomy of ammonia-oxidizing archaea and bacteria in the hyper-arid soils of the Antarctic Dry Valleys

    Directory of Open Access Journals (Sweden)

    Catarina Maria Magalhães

    2014-09-01

    Full Text Available The McMurdo Dry Valleys of Antarctica are considered to be one of the most physically and chemically extreme terrestrial environments on the Earth. However, little is known about the organisms involved in nitrogen transformations in these environments. In this study, we investigated the diversity and abundance of ammonia-oxidizing archaea (AOA and bacteria (AOB in four McMurdo Dry Valleys with highly variable soil geochemical properties and climatic conditions: Miers Valley, Upper Wright Valley, Beacon Valley and Battleship Promontory. The bacterial communities of these four Dry Valleys have been examined previously, and the results suggested that the extremely localized bacterial diversities are likely driven by the disparate physicochemical conditions associated with these locations. Here we showed that AOB and AOA amoA gene diversity was generally low; only four AOA and three AOB operational taxonomic units (OTUs were identified from a total of 420 AOA and AOB amoA clones. Quantitative PCR analysis of amoA genes revealed clear differences in the relative abundances of AOA and AOB amoA genes among samples from the four Dry Valleys. Although AOB amoA gene dominated the ammonia-oxidizing community in soils from Miers Valley and Battleship Promontory, AOA amoA gene were more abundant in samples from Upper Wright and Beacon Valleys, where the environmental conditions are considerably harsher (e.g., extremely low soil C/N ratios and much higher soil electrical conductivity. Correlations between environmental variables and amoA genes copy numbers, as examined by redundancy analysis (RDA, revealed that higher AOA/AOB ratios were closely related to soils with high salts and Cu contents and low pH. Our findings hint at a dichotomized distribution of AOA and AOB within the Dry Valleys, potentially driven by environmental constraints.

  15. Characterization of chasmoendolithic community in Miers Valley, McMurdo Dry Valleys, Antarctica.

    Science.gov (United States)

    Yung, Charmaine C M; Chan, Yuki; Lacap, Donnabella C; Pérez-Ortega, Sergio; de Los Rios-Murillo, Asuncion; Lee, Charles K; Cary, S Craig; Pointing, Stephen B

    2014-08-01

    The Antarctic Dry Valleys are unable to support higher plant and animal life and so microbial communities dominate biotic ecosystem processes. Soil communities are well characterized, but rocky surfaces have also emerged as a significant microbial habitat. Here, we identify extensive colonization of weathered granite on a landscape scale by chasmoendolithic microbial communities. A transect across north-facing and south-facing slopes plus valley floor moraines revealed 30-100 % of available substrate was colonized up to an altitude of 800 m. Communities were assessed at a multidomain level and were clearly distinct from those in surrounding soils and other rock-inhabiting cryptoendolithic and hypolithic communities. All colonized rocks were dominated by the cyanobacterial genus Leptolyngbya (Oscillatoriales), with heterotrophic bacteria, archaea, algae, and fungi also identified. Striking patterns in community distribution were evident with regard to microclimate as determined by aspect. Notably, a shift in cyanobacterial assemblages from Chroococcidiopsis-like phylotypes (Pleurocapsales) on colder-drier slopes, to Synechococcus-like phylotypes (Chroococcales) on warmer-wetter slopes. Greater relative abundance of known desiccation-tolerant bacterial taxa occurred on colder-drier slopes. Archaeal phylotypes indicated halotolerant taxa and also taxa possibly derived from nearby volcanic sources. Among the eukaryotes, the lichen photobiont Trebouxia (Chlorophyta) was ubiquitous, but known lichen-forming fungi were not recovered. Instead, fungal assemblages were dominated by ascomycetous yeasts. We conclude that chasmoendoliths likely constitute a significant geobiological phenomenon at lower elevations in granite-dominated Antarctic Dry Valley systems. PMID:24671755

  16. The Distribution and Identity of Edaphic Fungi in the McMurdo Dry Valleys

    Directory of Open Access Journals (Sweden)

    Lisa L. Dreesens

    2014-07-01

    Full Text Available Contrary to earlier assumptions, molecular evidence has demonstrated the presence of diverse and localized soil bacterial communities in the McMurdo Dry Valleys of Antarctica. Meanwhile, it remains unclear whether fungal signals so far detected in Dry Valley soils using both culture-based and molecular techniques represent adapted and ecologically active biomass or spores transported by wind. Through a systematic and quantitative molecular survey, we identified significant heterogeneities in soil fungal communities across the Dry Valleys that robustly correlate with heterogeneities in soil physicochemical properties. Community fingerprinting analysis and 454 pyrosequencing of the fungal ribosomal intergenic spacer region revealed different levels of heterogeneity in fungal diversity within individual Dry Valleys and a surprising abundance of Chytridiomycota species, whereas previous studies suggested that Dry Valley soils were dominated by Ascomycota and Basidiomycota. Critically, we identified significant differences in fungal community composition and structure of adjacent sites with no obvious barrier to aeolian transport between them. These findings suggest that edaphic fungi of the Antarctic Dry Valleys are adapted to local environments and represent an ecologically relevant (and possibly important heterotrophic component of the ecosystem.

  17. Salts in the dry valleys of Antartica

    Science.gov (United States)

    Gibson, E. K., Jr.; Presley, B. J.; Hatfield, J.

    1984-01-01

    The Dry Valleys of Antarctica are examples of polar deserts which are rare geological features on the Earth. Such deserts typically have high salinities associated with their closed-basin waters and on many surficial materials throughout them. In order to examine the possible sources for the salts observed in association with the soils in the Dry Valleys. The chloride and bromide concentrations of the water leachates from 58 soils and core samples were measured. The Cl/Br ratio for seawater is 289 and ratios measured for most of the 58 soils studied (greater than 85% of the soils studied) was larger than the seawater ratio (ratios typically were greater than 1000 and ranged up to 50,000). The enrichment in Cl relative to Br is strong evidence that the alts present within the soils were derived from seawater during ordinary evaporation processes, and not from the deposition of Cl and Br from aerosols or from rock weathering as has often been suggested.

  18. Revisiting Sustainable Development of Dry Valleys in Hengduan Mountains Region

    Institute of Scientific and Technical Information of China (English)

    TANG Ya; XIE Jiasui; SUN Hui

    2004-01-01

    Dry valleys are a striking geographic landscape in Hengduan Mountains Region and are characterized by low rainfall, desert type of vegetation and fragile environment. Past efforts and resources have been concentrated mainly on rehabilitation of degraded ecosystem and fragile environment,particularly reforestation, while socio-economic development has been largely overlooked. Despite successes in pocket areas, the overall trend of unsustainability and environmental deterioration are continuing. It is important to understand that uplift of the Tibetan Plateau is the root cause of development of dry valleys, and development and formation of dry valleys is a natural process. Human intervention has played a secondary role in development of dry valleys and degradation of dry valleys though human intervention in many cases has speeded up environmental degradation of the dry valleys. It is important to understand that dry valleys are climatic enclaves and an integrated approach that combines rehabilitation of degraded ecosystems and socio-economic development should be adopted if the overall goal of sustainable development of dry valleys is to be achieved. Promotion of niche-based cash crops, rural energy including hydropower, solar energy, biogas and fuelwood plantation is recommended as the priority activities.

  19. Zeolite Formation and Weathering Processes in Dry Valleys of Antartica: Martian Analogs

    Science.gov (United States)

    Gibson, E. K., Jr.; Wentworth, S. J.; McKay, D. S.; Socki, R. A.

    2004-01-01

    Terrestrial weathering processes in cold-desert climates such as the Dry Valleys of Antarctica may provide an excellent analog to chemical weathering and diagenesis of soils on Mars. Detailed studies of soil development and the chemical and mineralogical alterations occurring within soil columns in Wright Valley, Antarctica show incredible complexity in the upper meter of soil. Previous workers noted the ice-free Dry Valleys are the best terrestrial approximations to contemporary Mars. Images returned from the Pathfinder and Spirit landers show similarities to surfaces observed within the Dry Valleys. Similarities to Mars that exist in these valleys are: mean temperatures always below freezing (-20 C), no rainfall, sparse snowfall-rapidly removed by sublimation, desiccating winds, diurnal freeze-thaw cycles (even during daylight hours), low humidity, oxidative environment, relatively high solar radiation and low magnetic fields . The Dry Valley soils contain irregular distributions and low abundances of soil microorganisms that are somewhat unusual on Earth. Physical processes-such as sand abrasion-are dominant mechanisms of rock weathering in Antarctica. However, chemical weathering is also an important process even in such extreme climates. For example, ionic migration occurs even in frozen soils along liquid films on individual soil particles. It has also been shown that water with liquid-like properties is present in soils at temperatures on the order of approx.-80 C and it has been observed that the percentage of oxidized iron increases with increasing soil age and enrichments in oxidized iron occurs toward the surface. The presence of evaporates is evident and appear similar to "evaporite sites" within the Pathfinder and Spirit sites. Evaporites indicate ionic migration and chemical activity even in the permanently frozen zone. The presence of evaporates indicates that chemical weathering of rocks and possibly soils has been active. Authogenic zeolites have

  20. Chemistry and Mineralogy of Antarctica Dry Valley Soils: Implications for Mars

    Science.gov (United States)

    Quinn, J. E.; Golden, D. C.; Graff, T. G.; Ming, D. W.; Morris, R. V.; Douglas, S.; Kounaves, S. P.; McKay, C. P.; Tamppari, L, K.; Smith, P. H.; Zent, A. P.; Archer, P. D., Jr.

    2011-01-01

    The Antarctic Dry Valleys (ADV) comprise the largest ice-free region of Antarctica. Precipitation almost always occurs as snow, relative humidity is frequently low, and mean annual temperatures are about -20 C. The ADV soils have previously been categorized into three soil moisture regimes: subxerous, xerous and ultraxerous, based on elevation and climate influences. The subxerous regime is predominately a coastal zone soil, and has the highest average temperature and precipitation, while the ultraxerous regime occurs at high elevation (>1000 m) and have very low temperature and precipitation. The amounts and types of salts present in the soils vary between regions. The nature, origin and significance of salts in the ADV have been previously investigated. Substantial work has focused on soil formation in the ADVs, however, little work has focused on the mineralogy of secondary alteration phases. The dominant weathering process in the ADV region is physical weathering, however, chemical weathering has been well documented. The objective of this study was to characterize the chemistry and mineralogy, including the alteration mineralogy, of soils from two sites, a subxerous soil in Taylor Valley, and an ultraxerous soil in University Valley. The style of aqueous alteration in the ADVs may have implications for pedogenic processes on Mars.

  1. Mineralogy of Antarctica Dry Valley Soils: Implications for Pedogenic Processes on Mars

    Science.gov (United States)

    Quinn, J. E.; Ming, D. W.; Morris, R. V.; Douglas, S.; Kounaves, S. P.; McKay, C. P.; Tamppari, L, K.; Smith, P. H.; Zent, A. P.; Archer, P. D., Jr.

    2010-01-01

    The Antarctic Dry Valleys (ADVs) located in the Transantarctic Mountains are the coldest and driest locations on Earth. The mean annual air temperature is -20 C or less and the ADVs receive 100mm or less of precipitation annually in the form of snow. The cold and dry climate in the ADVs is one of the best terrestrial analogs for the climatic conditions on Mars [2]. The soils in the ADVs have been categorized into three soil moisture zones: subxerous, xerous and ultraxerous. The subxerous zone is a coastal region in which soils have ice-cemented permafrost relatively close to the surface. Moisture is available in relatively large amounts and soil temperatures are above freezing throughout the soil profile (above ice permafrost) in summer months. The xerous zone, the most widespread of the three zones, is an inland region with a climate midway between the subxerous and ultraxerous. The soils from this zone have dry permafrost at moderate depths (30-75cm) but have sufficient water in the upper soil horizons to allow leaching of soluble materials. The ultraxerous zone is a high elevation zone, where both temperature and precipitation amounts are very low resulting in dry permafrost throughout the soil profile. The three moisture regime regions are similar to the three microclimatic zones (coastal thaw, inland mixed, stable upland) defined by Marchant and Head.

  2. Cold adaptive traits revealed by comparative genomic analysis of the eurypsychrophile Rhodococcus sp. JG3 isolated from high elevation McMurdo Dry Valley permafrost, Antarctica.

    Science.gov (United States)

    Goordial, Jacqueline; Raymond-Bouchard, Isabelle; Zolotarov, Yevgen; de Bethencourt, Luis; Ronholm, Jennifer; Shapiro, Nicole; Woyke, Tanja; Stromvik, Martina; Greer, Charles W; Bakermans, Corien; Whyte, Lyle

    2016-02-01

    The permafrost soils of the high elevation McMurdo Dry Valleys are the most cold, desiccating and oligotrophic on Earth. Rhodococcus sp. JG3 is one of very few bacterial isolates from Antarctic Dry Valley permafrost, and displays subzero growth down to -5°C. To understand how Rhodococcus sp. JG3 is able to survive extreme permafrost conditions and be metabolically active at subzero temperatures, we sequenced its genome and compared it to the genomes of 14 mesophilic rhodococci. Rhodococcus sp. JG3 possessed a higher copy number of genes for general stress response, UV protection and protection from cold shock, osmotic stress and oxidative stress. We characterized genome wide molecular adaptations to cold, and identified genes that had amino acid compositions favourable for increased flexibility and functionality at low temperatures. Rhodococcus sp. JG3 possesses multiple complimentary strategies which may enable its survival in some of the harshest permafrost on Earth. PMID:26637477

  3. 77 FR 60477 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2012-10-03

    ... amended by the Antarctic Science, Tourism and Conservation Act of 1996, has developed regulations for the... ASPA 116-New ] College Valley, Cape Bird, ASPA 121-Cape Royds, and ASPA 124-Cape Crozier to collect... these habitats with those identified in the Dry Valleys. Location ASPA 116-New College Valley, Cape...

  4. 1:250,000-scale geology of the Dry Valley Hydrographic Area, Nevada and California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This dataset consists of digital geologic data for the Dry Valley Hydrographic area, Nevada and California. It was compiled from individual 1:250,000-scale geologic...

  5. Soil Geochemical Control Over Nematode Populations in Bull Pass, McMurdo Dry Valleys, Antarctica

    Science.gov (United States)

    Poage, M. A.; Barrett, J. E.; Virginia, R. A.; Wall, D. H.

    2005-12-01

    The McMurdo Dry Valleys occupy the largest ice-free region of Antarctica and are characterized by climatic conditions among the most extreme on Earth. Despite the harsh environmental conditions, some soils of the dry valleys host simple low-diversity ecosystems dominated by microbes and several taxa of metazoans, predominantly nematodes. Distributions, abundance, and diversity of these biota appear to be related to the highly variable soil geochemistry (pH, conductivity, nitrate, sulfate, chloride) of the dry valleys. Bull Pass is a glacially carved valley within the dry valleys. An ancient lake margin near the valley floor creates a continuous gradient spanning the full range of geochemical parameters found across the entire McMurdo Dry Valleys system. This unique setting provides the opportunity to systematically investigate the soil geochemical control on local biodiversity and establish, on the spatial scale of hundreds of meters, correlations between nematode populations and individual geochemical parameters that have application at the regional scale. We measured soil geochemistry and nematode population data from a 1500-meter transect across this ancient lake margin. There were significant negative correlations between live nematode abundance and concentrations of soil nitrate, sulfate and chloride as well as total soil salinity, consistent with recent laboratory experiments showing strong salinity inhibition of nematode survival. A logistical regression analysis based on a compilation of published datasets from across the dry valleys was designed to calculate the probably of live nematode populations occurring given a particular soil chemistry, using the dataset from the Bull Pass transect as a case study to field-test the model. Small-scale chemical and biological gradients can provide insights on the distribution of soil biota at much larger regional scales.

  6. SLOPE LITHOLOGIC PROPERTY, SOIL MOISTURE CONDITION AND REVEGETATION IN DRY-HOT VALLEY OF JINSHA RIVER

    Institute of Scientific and Technical Information of China (English)

    XIONG Dong-hong; ZHOU Hong-yi; YANG Zhong; ZHANG Xin-bao

    2005-01-01

    The dry-hot valley of the Jinsha River is one of the typical eco-fragile areas in Southwest China, as well as a focus ofrevegetation study in the upper and middle reaches of the Changjiang River. Due to its extremely dry and hot climate, severely degraded vegetation and the intense soil and water loss, there are extreme difficulties in vegetation restoration in this area and no great breakthrough has ever been achieved on studies of revegetation over the last several decades. Through over ten years' research conducted in the typical areas-the Yuanmou dry-hot valley, the authors found that the lithologic property is one of the crucial factors determining soil moisture conditions and vegetation types in the dry-hot valley, and the rainfall infiltration capability is also one of the key factors affecting the tree growth. Then the revegetation zoning based on different slopes was conducted and revegetation patterns for different zones were proposed.

  7. Hyperinflation of surfaces in lower Beacon Valley, Dry Valleys, Antarctica: new process and new clues about fluctuations of Taylor Glacier

    Science.gov (United States)

    Sletten, R. S.; Hallet, B.; Hagedorn, B.; Stone, J.

    2009-12-01

    Soil inflation in dry environments is a common occurrence in areas where extensive desert pavements overlie silt-size particles of eolian origin. Another type of surface inflation, which we term hyperinflation, has been documented in the Dry Valleys where fines drop into contraction cracks that annually open and close 0.5 to 1.5 cm. Particles of local or eolian origin that are smaller than the crack opening can fall into the cracks,. We have cored over 30 m into such a hyperinflated surface in lower Beacon Valley. Large clasts several cm to over 10 m are suspended on top of the finer sediments leading to the characteristic rocky surface of Beacon Valley. These processes have been active over at least several million years based on cosmogenic 10 Be and 26 Al profiles with depth. This new hyperinflation has much in common with the progressive addition of ice into the permafrost in Siberia forming the classic edoma or ice-wedge complexes. We propose that these “sand-wedge complexes” form in a similar way but are only sand because liquid water seldom forms in sufficient amounts to fill the contraction cracks in the hyperarid Beacon Valley. Furthermore, our analysis of a 10-m core collected earlier reveal historical waxing and waning of the Taylor Glacier over lower Beacon Valley in the past several million years; one of these incursions of ice may be responsible for the formation of buried glacial ice found in middle Beacon Valley. We are currently processing our 30-m core and believe that this will improve definition of the extent and chronology of Taylor Glacier advances.

  8. Diversity and ecological ranges of plant species from dry inter-Andean valleys

    DEFF Research Database (Denmark)

    Quintana, Catalina

    animals, but unfortunately only very few botanical studies have been carried out in these areas. This thesis intends to shed light on the vegetation of the Dry Ecuadorean Inter-Andean Valleys in four chapters, each with a different focus. 1) A review paper that summarizes all scientific knowledge of...... Ecuadorian dry inter-Andean valleys vegetation, including information related to the physical settings as well as to the vegetation and flora of the valleys. 2) This chapter unveils the influence of disturbance, water availability and low temperature in shaping species composition and occurrence. We found...... that there were significant, contrasting patterns between life forms (trees, herbs and shrubs) and that combining trees and shrubs in one broad category confound patterns and ecological processes. 3) This paper demonstrates that 70% of species collected in Ecuadorian DIAVs are shared amongst dry...

  9. Surface layer response to topographic solar shading in Antarctica's dry valleys

    Science.gov (United States)

    Katurji, Marwan; Zawar-Reza, Peyman; Zhong, Shiyuan

    2013-11-01

    The effects of topographic shading on local flow transitioning and atmospheric surface layer properties are investigated using observational data from the Miers Valley, one of the dry valleys of Antarctica. A unique data set was collected during a 9 day period in the summer of 2012 using an eddy covariance system and a sound detection and ranging that provided vertical profiles of wind and turbulence characteristics in the surface layer and the lower part of the boundary layer within the Miers Valley. This data set is ideal for investigating the dynamics of flow transitioning due to topographic shading, without the atmosphere experiencing complete darkness. The lack of atmospheric humidity, soil moisture, and surface vegetation in the dry valleys creates an atmosphere within which the microclimatic responses are amplified, and as a result, the valley atmosphere is extremely sensitive to solar radiation. The entire measured valley boundary layer (up to 250 m above ground level) feels the transition from an unstable to a stable stratification as the surface temperature drops by 10°C in response to the topographic shading. Wavelet analysis reveals the dynamics of flow deceleration, stagnation, and oscillations as the flow transitions from an unstable to a stable boundary layer. The larger air mass (along valley) scales to the longer terrain fetch, and as the shade is cast over the valley, it retains some of the longer wavelengths of the flow. The cross-valley component influenced by the slopes is quicker to adjust to short-period oscillations and takes around three more hours before it couples with the oscillatory pattern of the along-valley flow.

  10. Pothole and channel system formation in the McMurdo Dry Valleys of Antarctica: New insights from cosmogenic nuclides

    Science.gov (United States)

    Middleton, Jennifer L.; Ackert, Robert P.; Mukhopadhyay, Sujoy

    2012-11-01

    Large pothole and channel features (˜15 m deep, ˜30 m wide) carved into the Beacon Sandstone in the upland Dry Valleys of Antarctica have been used to infer catastrophic subglacial flooding beneath an expanded East Antarctic Ice Sheet that overran the Transantarctic Mountains during the mid-Miocene. Though the age and erosion rates of these geomorphic features have not been quantified, preservation of the potholes and channels has been attributed to negligible erosion under consistent polar desert conditions since the retreat of the ice sheet at ˜14 Ma. We present cosmogenic 21Ne and 10Be data from samples collected along vertical transects of pothole and channel walls, as well as from intervening benches, within Battleship Promontory in the Convoy Range and within Sessrumnir Valley in the Western Asgard Range to constrain their exposure history. Measurements of fissiogenic 136Xe are used to estimate a nucleogenic 21Ne concentration in the Beacon Sandstone of 7.7±2.4×106 atoms g-1 and to correct our 21Ne data for this component. Sample concentrations of cosmogenic 21Ne and 10Be are significantly lower than previously measured in the regional bedrock and reveal steady state erosion rates ranging from 99 to 171 cm Ma-1 in Battleship Promontory and from 59 to 383 cm Ma-1 in Sessrumnir Valley. Continuous exposure at such erosion rates would remove 8-54 m of bedrock over a 14 Ma period, a length scale similar to the features themselves, and suggests that these systems could have formed primarily through subaerial erosive processes. Alternatively, if the features formed subglacially in the Miocene, then a complex erosion and exposure history must have occurred to prevent the accumulation of cosmogenic nuclides to levels higher than those observed. Either prolonged and extensive ice cover of these features prior to 2 Ma, or a threefold increase in erosion rates during the Plio-Pleistocene could produce the 21Ne and 10Be concentrations measured here. Ultimately, all

  11. A novel Antarctic microbial endolithic community within gypsum crusts.

    Science.gov (United States)

    Hughes, Kevin A; Lawley, Blair

    2003-07-01

    A novel endolithic microbial habitat is described from a climatically extreme site at Two Step Cliffs, Alexander Island, Antarctic Peninsula (71 degrees 54'S, 68 degrees 13'W). Small endolithic colonies (endolithic communities are less extensive than those of the Dry Valleys, continental Antarctica, probably owing to only recent deglaciation (<7000 year ago). PMID:12823188

  12. Cosmogenic 3He concentrations in ancient flood deposits from the Coombs Hills, northern Dry Valleys, East Antarctica: interpreting exposure ages and erosion rates

    Science.gov (United States)

    Margerison, H. R.; Phillips, W. M.; Stuart, F. M.; Sugden, D. E.

    2005-01-01

    In situ produced cosmogenic 3He analyses provide independent support for the model of a stable, hyper-arid polar climate persisting in East Antarctica since the mid-Miocene and provide quantitative constraints on long-term rates of erosion within the Dry Valleys. In the Coombs Hills area, a series of cobble-size boulders form mega-ripples with wavelengths of approximately 50 m. Their topographic position and association with features characteristic of scabland, such as stripped, corrugated bedrock surfaces, indicate the boulders were deposited by subglacial floodwaters. Such outburst flooding could only have occurred during overriding of the northern Dry Valleys by a greatly expanded East Antarctic ice sheet. Timing of the overriding episode has been previously assigned to 14.8 to 13.6 Ma by correlation with volcanic ash deposits dated by 40Ar/39Ar in the Asgard Range of the Dry Valleys. Cosmogenic 3He concentrations in clinopyroxene from Ferrar dolerite boulders are consistent with 8.6 to 10.4 Ma exposure, calculated using scaling factors appropriate for Antarctica and assuming zero erosion. These are among the oldest surface exposure dates yet measured on Earth, but are not however consistent with the 40Ar/39Ar chronology used to define the age of the landscape due to unconstrained levels of erosion. Erosion rates of 0.03-0.06 m Ma-1 are necessary to have produced the measured boulder exposure age if they were deposited at 14.8 Ma. These are less than half the steady-state erosion rate derived from cosmogenic 3He in the nearby bedrock surfaces (0.17 m Ma-1) and testify to the extreme stability of the landscape.

  13. Abundance, Distribution and Cycling of Organic Carbon and Nitrogen in University Valley (McMurdo Dry Valleys of Antarctica) Permafrost Soils with Differing Ground Thermal and Moisture Conditions: Analogue to C-N Cycle on Mars

    Science.gov (United States)

    Faucher, B. F.; Lacelle, D. L.; Davila, A. D.; Pollard, W. P.; McKay, C. P. M.

    2016-05-01

    High elevation McMurdo Dry Valleys of Antarctica are key Mars analogue sites. Our investigation focuses on the link between ground ice origin, distribution and cycling of organic carbon and nitrogen in University Valley, and its soil habitability.

  14. Part 2: Sedimentary geology of the Valles, Marineris, Mars and Antarctic dry valley lakes

    International Nuclear Information System (INIS)

    Detailed mapping of the layered deposits in the Valles Marineris, Mars from high-resolution Viking orbiter images revealed that they from plateaus of rhythmically layered material whose bases are in the lowest elevations of the canyon floors, and whose tops are within a few hundred meters in elevation of the surrounding plateaus. Four hypotheses for the origin of the layered deposits were considered: that they are eolian deposits; that they are remnants of the same material as the canyon walls; that they are explosive volcanic deposits; or that they were deposited in standing bodies of water. There are serious morphologic objections to each of the first three. The deposition of the layered deposits in standing bodies of water best explains their lateral continuity, horizontality, great thickness, rhythmic nature, and stratigraphic relationships with other units within the canyons. The Martian climatic history indicated that any ancient lakes were ice covered. Two methods for transporting sediment through a cover of ice on a martian lake appear to be feasible. Based on the presently available data, along with the theoretical calculations presented, it appears most likely that the layered deposits in the Valles Marineris were laid down in standing bodies of water

  15. Diversity patterns, environmental drivers and changes in vegetation composition in dry inter-Andean valleys

    DEFF Research Database (Denmark)

    Quintana, Catalina; Girardello, Marco; Barfod, Anders;

    2016-01-01

    Aims We studied diversity, patterns of endemism and turnover of vegetation composition in dry inter-Andean valleys (DIAVs) where little is known about the influence of the abiotic drivers controlling plant species composition and occurrences, and the life forms that contribute most to α- and β......-diversity correlated with latitude? (iii) what are the major environmental drivers controlling spatial patterns in species composition and occurrence? Methods We established 63 transects of 5 × 100 m in areas with DIAV vegetation, impacted as little as possible by human activities. In each transect, all mature trees...

  16. Airborne bacterial populations above desert soils of the McMurdo Dry Valleys, Antarctica.

    Science.gov (United States)

    Bottos, Eric M; Woo, Anthony C; Zawar-Reza, Peyman; Pointing, Stephen B; Cary, Stephen C

    2014-01-01

    Bacteria are assumed to disperse widely via aerosolized transport due to their small size and resilience. The question of microbial endemicity in isolated populations is directly related to the level of airborne exogenous inputs, yet this has proven hard to identify. The ice-free terrestrial ecosystem of Antarctica, a geographically and climatically isolated continent, was used to interrogate microbial bio-aerosols in relation to the surrounding ecology and climate. High-throughput sequencing of bacterial ribosomal RNA (rRNA) genes was combined with analyses of climate patterns during an austral summer. In general terms, the aerosols were dominated by Firmicutes, whereas surrounding soils supported Actinobacteria-dominated communities. The most abundant taxa were also common to aerosols from other continents, suggesting that a distinct bio-aerosol community is widely dispersed. No evidence for significant marine input to bioaerosols was found at this maritime valley site, instead local influence was largely from nearby volcanic sources. Back trajectory analysis revealed transport of incoming regional air masses across the Antarctic Plateau, and this is envisaged as a strong selective force. It is postulated that local soil microbial dispersal occurs largely via stochastic mobilization of mineral soil particulates. PMID:24121801

  17. Nearing the cold-arid limits of microbial life in permafrost of an upper dry valley, Antarctica.

    Science.gov (United States)

    Goordial, Jacqueline; Davila, Alfonso; Lacelle, Denis; Pollard, Wayne; Marinova, Margarita M; Greer, Charles W; DiRuggiero, Jocelyn; McKay, Christopher P; Whyte, Lyle G

    2016-07-01

    Some of the coldest and driest permafrost soils on Earth are located in the high-elevation McMurdo Dry Valleys (MDVs) of Antarctica, but little is known about the permafrost microbial communities other than that microorganisms are present in these valleys. Here, we describe the microbiology and habitable conditions of highly unique dry and ice-cemented permafrost in University Valley, one of the coldest and driest regions in the MDVs (1700 m above sea level; mean temperature -23 °C; no degree days above freezing), where the ice in permafrost originates from vapour deposition rather than liquid water. We found that culturable and total microbial biomass in University Valley was extremely low, and microbial activity under ambient conditions was undetectable. Our results contrast with reports from the lower-elevation Dry Valleys and Arctic permafrost soils where active microbial populations are found, suggesting that the combination of severe cold, aridity, oligotrophy of University Valley permafrost soils severely limit microbial activity and survival. PMID:27323892

  18. Subsurface imaging reveals a confined aquifer beneath an ice-sealed Antarctic lake

    DEFF Research Database (Denmark)

    Dugan, H. A.; Doran, P. T.; Tulaczyk, S.;

    2015-01-01

    Liquid water oases are rare under extreme cold desert conditions found in the Antarctic McMurdo Dry Valleys. Here we report geophysical results that indicate that Lake Vida, one of the largest lakes in the region, is nearly frozen and underlain by widespread cryoconcentrated brine. A ground penet...

  19. Late Pleistocene ice-shelf, valley-glacier and ice-sheet interactions on Alexander Island, Antarctic Peninsula: implications for climatic and ice-volume changes

    Science.gov (United States)

    Davies, Bethan; Hambrey, Michael; Glasser, Neil; Smellie, John; Carrivick, Jonathan; Bentley, Michael

    2014-05-01

    Recent rapid warming across the Antarctic Peninsula has resulted in ice-sheet thinning, dramatic ice-shelf collapse, acceleration of ice-flow velocities and widespread glacier recession. Reconstructing past rates, volumes and magnitudes of cryospheric change, particularly with respect to the former configuration of ice sheets and ice shelves, and their response to changing oceanic and climatic regimes, is vital in providing a context for this change, in order to improve predictions of future ice-sheet behaviour, and to provide glacio-isostatic adjustment corrections for gravimetric measurements of contemporary ice loss. This research aimed to investigate valley glacier and ice-shelf interactions during the Last Glacial Maximum (LGM) and Holocene Epoch across George VI Sound and Alexander Island, western Antarctic Peninsula, an area with a well-preserved but poorly dated record. We identify four principal stratigraphic units: (1) a high-elevation drift with Alexander Island erratics only (interpreted as recording older advances of ice from the interior of the island), (2) a lower-elevation drift with exotic Palmer Land erratics (interpreted as ice-shelf moraine, representing incursions of George VI Ice Shelf onto Ablation Point Massif), (3) multiple overlapping sequences of valley glacier moraine and ice-shelf moraine, presumed to be Holocene in age, and (4) more recent processes and units, including frozen epishelf lakes, slope processes and alluvial fans. On-going cosmogenic nuclide dating on these sediments (in progress; 25 10Be exposure ages) has the potential to unlock the complex history and interactions of ice streams, valley glaciers and ice shelves in this area. This work will also provide the first long-term record of sea-level indicators, allowing the first estimates of glacial unloading, rates of uplift and ice-sheet thinning to be calculated. The Holocene record of the ice shelf, preserved in the younger ice-shelf moraines and in the overlapping

  20. The Vanda Dike Swarm, Dry Valleys, Antarctica II: Geochemistry and Geochronology

    Science.gov (United States)

    Harpp, K. S.; Bray, B.; Geist, D.; Garcia, M. O.

    2014-12-01

    One of the most spectacular features of the Dry Valleys of Antarctica is the Vanda Dikes, an exceptionally well exposed swarm of >600 Cambro-Ordovician dikes emplaced near the end of the Ross Orogeny. Whereas their compositions range from mafic to felsic, they are primarily bimodal, with few intermediate compositions between 56 and 66 wt.% SiO2; mafic dikes vary from calc-alkaline to shoshonitic. The suite of dikes exhibits 87Sr/86Sr from 0.704-0.711 and 143Nd/144Nd from 0.51217-0.51242; the wide range of Nd isotopic ratios may reflect variable degrees of assimilation of the subcontinental lithospheric mantle inherited during Proterozoic crustal generation and the Ross Orogeny. The mafic dikes have a subduction-related trace element signature and we propose they originated as melts of the subcontinental lithospheric mantle. The siliceous suite is characterized by elevated 87Sr/86Sri and an average Nd model age (τDM) of 1444 Ma, suggesting that the silica-rich dikes were generated by melting of or contamination by a Neoproterozoic crustal source, followed by variable fractional crystallization and further continental crust contamination. Analysis of zircons by CA-TIMS U-Pb geochronology reveals that the dikes were emplaced in a narrow time window, from 491 to 495 ± 0.3 Ma, which falls between emplacement of a synorogenic pluton (DV1) and extension-related plutons (DV2). Thus, we conclude that the dikes were intruded during the transition of the Ross Orogeny from collision to extension. During orogenic uplift and collapse, decompression melting of the subcontinental lithospheric mantle was initiated, resulting in the emplacement of the Vanda Dike Swarm. Because there is a strong correlation between dike age and latitude, the dikes can be used to map the progress of the collision-extension transition during the Ross Orogeny across the Dry Valleys.

  1. Granitoids of the Dry Valleys area, southern Victoria Land, Antarctica : plutons, field relationships, and isotopic dating

    International Nuclear Information System (INIS)

    Detailed mapping throughout much of the Dry Valleys area indicates the region is underlain by 15 major granitoid plutons and numerous smaller plugs and dikes. Intrusive relationships of these plutons and dikes indicate repeated intrusion of superficially similar granitoids at different times. Sufficient internal lithologic variation occurs within individual plutons, to allow correlation with several of the previously defined granitoid units based on lithologic character. Consequently, previous subdivision schemes based on lithology are no longer tenable and are here replaced with a subdivision scheme based on the identification of individual plutons. The elongate, concordant Bonney, Denton, Cavendish, and Wheeler Plutons, which range in composition between monzodiorite and granodiorite, are the oldest relatively undeformed plutons in the Dry Valleys area. Each pluton is characterised by flow alignment of K-feldspar megacrysts, hornblende, biotite, and mafic enclaves. Field relationships and radiometric dating indicate these are deep-level plutons, emplaced synchronous with upper amphibolite facies metamorphism of the adjacent Koettlitz Group between 589 and 490 Ma ago. Elongate, discordant plutons of equigranular homogeneous biotite granodiorite and granite (Hedley, Valhalla, St Johns, Suess) were subsequently emplaced by stoping at a relatively high crustal level at 490 Ma. These eight plutons are cut by numerous swarms of Vanda mafic and felsic porphyry dikes. The ovoid, discordant, high level Pearse, Nibelungen, Orestes, Brownworth, Swinford, and Harker Plutons, emplaced between c. 486 and 477 Ma, display mutually crosscutting relationships with the youngest of the Vanda dikes. These younger plutons range in composition between monzonite and granite. Some are characterised by K-feldspar megacrystic textures superficially similar to some of the oldest concordant plutons. (author). 57 refs.; 2 tabs.; 4 figs

  2. A New Xeromorphic Species of Clusia (Clusiaceae) from Dry Valleys of Northern Peru

    DEFF Research Database (Denmark)

    Gustafsson, Mats

    2010-01-01

    Clusia magnoliiflora M. H. G. Gust. is described as new for the Clusiaceae. It grows in dry scrub in the river valleys of the Marañón and its tributaries in northern Peru, a kind of habitat that harbors very few Clusia species. The species is distinct on account of its extremely thick, obovate...

  3. Dry extraction of 14C02 and 14C0 from Antarctic ice

    NARCIS (Netherlands)

    Roijen, J.J. van; Bintanja, R.; Borg, R. van den; Broeke, M.R. van den; Jong, A.F.M. de; Oerlemans, J.

    1994-01-01

    A dry extraction method was used to obtain trapped CO, of 2-5 kg ice samples from a blue ice zone in East Antarctica. In situ produced 14C was also extracted in 14C0, and 14C0 concentrations at a ratio of 3.4 f 0.9. Correction of trapped 14C0, from in situ resulted in ice dates in the range 5-15 ka.

  4. Bridging dry spells for maize cropping through supplemental irrigation in the Central Rift Valley of Ethiopia

    Science.gov (United States)

    Muluneh Bitew, Alemayehu; Keesstra, Saskia; Stroosnijder, Leo

    2015-04-01

    Maize yield in the Central Rift Valley of Ethiopia (CRV) suffers from dry spells at sensitive growth stages. Risk of crop failure makes farmers reluctant to invest in fertilizer. This makes the CRV food insecure. There are farms with well-maintained terraces and Rain Water Harvesting (RWH) systems using concrete farms ponds. We tested the hypothesis that in these farms supplemental irrigation with simultaneous crop intensification might boost production of a small maize area sufficient to improve food security. Intensification includes a higher plant density of a hybrid variety under optimum fertilization. First we assessed the probability of occurrence of dry spells. Then we estimated the availability of sufficient runoff in the ponds in dry years. During 2012 (dry) and 2013 (wet) on-farm field research was conducted with 10 combinations of supplemental irrigation and plant density. The simplest was rainfed farming with 30,000 plants ha-1. The most advanced was no water stress and 75,000 plants ha-1. Finally we compared our on-farm yield with that of neighbouring farmers. Because 2013 was a wet year no irrigation was needed. Our long term daily rainfall (1970-2011) analysis proves the occurrence of dry spells during the onset of the maize (Belg months March and April). In March there is hardly enough water in the ponds. So, we advise later sowing. Starting from April available water (runoff from a 2.2 ha catchment) matches crop water requirement (for 0.5 ha maize). Significant differences between grain and total biomass yield were observed between rainfed and other irrigation levels. However, since the largest difference is only 12%, the investment in irrigation non-critical drought years is not worth the effort. There was also a limited effect (18-22%) of increasing plant density. So, we advise not to use more than 45,000 plants ha-1. The grain yield and total biomass difference between farmers own practice and our on-farm research was 101% and 84% respectively

  5. Antarctic Astrobiology

    Science.gov (United States)

    McKay, Christopher P.

    2003-01-01

    Stars may be cold and dry today but there is compelling evidence that earlier in its history Mars did have liquid water. This evidence comes from the images taken from orbital spacecraft. The dry valleys of Antarctica comprise the largest ice-free region on that continent. The valleys are a cold desert environment with mean annual temperatures of -20 C. The lakes in the dry valleys of Antarctica provide an example of the physical processes that can maintain large bodies of liquid water under mean annual temperatures well below freezing. Biologically these lakes are also important analogs because of the plankton and benthic communities of microorganisms that thrive there. Life could have existed in lakes on Mars an ecological similar conditions.

  6. Rodent consumption by Philodryas psammophidea (Serpentes: Colubridae), from the inter-andean dry valleys of central Bolivia

    OpenAIRE

    Quinteros-Muñoz, Oliver; Peñaranda, Diego A.; Navarro, Freddy

    2010-01-01

    In May 18, 2009 we found an adult female of Philodryas psammophidea (930 mm SVL), at a side of a crop field in the Tabacal valley (18º23'7.42" S – 64º38'7.88" W, 2015 m), Narciso Campero province southern Cochabamba, Bolivia. Ecologically, this valley belongs to the Inter-Andean Dry Forests of Bolivia. In the stomach of the snake probably killed by a settler, there was an adult female of Graomys domorum (Phyllotini; Sigmodontidae), a native rodent species widely distributed in the r...

  7. Rodent consumption by Philodryas psammophidea (Serpentes: Colubridae, from the inter-andean dry valleys of central Bolivia

    Directory of Open Access Journals (Sweden)

    Quinteros-Muñoz, Oliver

    2010-12-01

    Full Text Available In May 18, 2009 we found an adult female of Philodryas psammophidea (930 mm SVL, at a side of a crop field in the Tabacal valley (18º23'7.42" S – 64º38'7.88" W, 2015 m, Narciso Campero province southern Cochabamba, Bolivia. Ecologically, this valley belongs to the Inter-Andean Dry Forests of Bolivia. In the stomach of the snake probably killed by a settler, there was an adult female of Graomys domorum (Phyllotini; Sigmodontidae, a native rodent species widely distributed in the region.

  8. Controls and variability of solute and sedimentary fluxes in Antarctic and sub-Antarctic Environments

    Science.gov (United States)

    Zwolinski, Zbigniew

    2015-04-01

    The currently prepared SEDIBUD Book on "Source-to-Sink Fluxes in Undisturbed Cold Environments" (edited by Achim A. Beylich, John C. Dixon and Zbigniew Zwolinski and published by Cambridge University Press) is summarizing and synthesizing the achievements of the International Association of Geomorphologists` (I.A.G./A.I.G.) Working Group SEDIBUD (Sediment Budgets in Cold Environments), which has been active since 2005 (http://www.geomorph.org/wg/wgsb.html). The book comprises five parts. One of them is part about sub-Antarctic and Antarctic Environments. This part "Sub-Antarctic and Antarctic Environments" describes two different environments, namely oceanic and continental ones. Each part contains results of research on environmental drivers and rates of contemporary solute and sedimentary fluxes in selected sites. Apart from describing the environmental conditions of the whole continent of Antarctica and sub-Antarctic islands (Zb.Zwolinski, M.Kejna, A.N.Lastochkin, A.Zhirov, S.Boltramovich) this part of the book characterizes terrestrial polar oases free from multi-year ice and snow covers (Zb.Zwolinski). The detailed results of geoecological and sedimentological research come from different parts of Antarctica. Antarctic continental shelf (E.Isla) is an example of sub-Antarctic oceanic environment. South Shetlands, especially King George Island (Zb.Zwolinski, M.Kejna, G.Rachlewicz, I.Sobota, J.Szpikowski), is an example of sub-Antarctic terrestrial environment. Antarctic Peninsula (G.Vieira, M.Francelino, J.C.Fernandes) and surroundings of McMurdo Dry Valleys (W.B.Lyons, K.A.Welch, J.Levy, A.Fountain, D.McKnight) are examples of Antarctic continental environments. The key goals of the Antarctic and sub-Antarctic book chapters are following: (i) identify the main environmental drivers and rates of contemporary solute and sedimentary fluxes, and (ii) model possible effects of projected climate change on solute and sedimentary fluxes in cold climate environments

  9. Rainfall infiltration on hilly slopes under various lithology and its effect on tree growth in the dry-hot valley

    Institute of Scientific and Technical Information of China (English)

    YANG; Zhong; XIONG; Donghong; ZHOU; Hongyi; ZHANG; Xinbao

    2003-01-01

    Revegetation is very difficult in dry-hot valleys in China. Rainfall infiltration capability on hilly slopes is one of the key factors determining soil moisture conditions and tree growth in the dry-hot valley. Low rainfall infiltration often results in soil drought on slopes under the dry-hot valleys climate. Rainfall infiltration capability varies greatly with the difference of slope lithologic porosity. The infiltration rates of five lithologic slope-types, Schist Slope, Grit Slope, Gravel Slope, the slightly eroded Mudstone Slope and the intensively eroded Mudstone Slope, are 1.40-8.67, 6.33, 0.69-2.20, 0.6-1.3 and 0.03-0.63 mm/min, respectively. With its viscid compact soil body and low infiltration capability which causes little infiltrating rainfall, mudstone slope can afford little effective supply to soil water and leads to serious drought of soil in dry seasons, resulting in cessation of growth or even wide-spread death of trees due to physiological damage for the excessive deficit of water in dry season and also the low productivity of stands. Hence, it is extremely difficult to restore vegetation on this type of slope. The other four lithologic slope-types, however, with well-developed soil crevice, high infiltration capability and thus more infiltrating rainfall, can afford more available soil water supply and the trees on them can obtain better growth and relatively higher productivity, compared with those on Mudstone Slope. Revegetation in dry-hot valleys is controlled by the soil moisture conditions of different slope-types, and it can be implemented by relying on the dominative life-form plant species, the suitable spatial arrangement of different life-forms of arbor-shrub-herb species, and the establishment of ecological community relationship between vegetation and soil moisture in habits. On the other hand, ground making measures for forestation and the runoff-collecting engineering measures to increase the rainfall infiltration are the major

  10. McMurdo Dry Valleys, Antarctica - A Mars Phoenix Mission Analog

    Science.gov (United States)

    Tamppari, L. K.; Anderson, R. M.; Archer, D.; Douglas, S.; Kounaves, S. P.; McKay, C. P.; Ming, Douglas W.; Moore, Q.; Quinn, J. E.; Smith, P. H.; Stroble, S.; Zent, A. P.

    2010-01-01

    The Phoenix mission (PHX; May 25 - Nov. 2, 2008) studied the north polar region of Mars (68deg N) to understand the history of water and potential for habitability. Phoenix carried with it a wet chemistry lab (WCL) capable of determining the basic solution chemistry of the soil and the pH value, a thermal and evolved-gas analyzer capable of determining the mineralogy of the soil and detecting ice, microscopes capable of seeing soil particle shapes, sizes and colors at very high resolution, and a soil probe (TECP) capable of detecting unfrozen water in the soil. PHX coincided with an international effort to study the Earth s polar regions named the International Polar Year (IPY; 2007-2008). The best known Earth analog to the Martian high-northern plains, where Phoenix landed, are the McMurdo Dry Valleys (MDV), Antarctica (Fig. 1). Thus, the IPY afforded a unique opportunity to study the MDV with the same foci - history of water and habitability - as PHX. In austral summer 2007, our team took engineering models of WCL and TECP into the MDV and performed analgous measurements. We also collected sterile samples and analyzed them in our home laboratories using state-of-the-art tools. While PHX was not designed to perform biologic analyses, we were able to do so with the MDV analog samples collected.

  11. Audiomagnetotelluric Data and Preliminary Two-Dimensional Models from Spring, Dry Lake, and Delamar Valleys, Nevada

    Science.gov (United States)

    McPhee, Darcy K.; Chuchel, Bruce A.; Pellerin, Louise

    2008-01-01

    This report presents audiomagnetotelluric (AMT) data along fourteen profiles in Spring, Delamar, and Dry Lake Valleys, and the corresponding preliminary two-dimensional (2-D) inverse models. The AMT method is a valuable tool for estimating the electrical resistivity of the Earth over depth ranges from a few meters to less than one kilometer, and it is important for revealing subsurface structure and stratigraphy within the Basin and Range province of eastern Nevada, which can be used to define the geohydrologic framework of the region. We collected AMT data by using the Geometrics StrataGem EH4 system. Profiles were 0.7 - 3.2 km in length with station spacing of 50-400 m. Data were recorded in a coordinate system parallel to and perpendicular to the regional geologic-strike direction with Z positive down. We show AMT station locations, sounding curves of apparent resistivity, phase, and coherency, and 2-D models of subsurface resistivity along the profiles. The 2-D inverse models are computed from the transverse electric (TE), transverse magnetic (TM), and TE+TM mode data by using a conjugate gradient, finite-difference method. Preliminary interpretation of the 2-D models defines the structural framework of the basins and the resistivity contrasts between alluvial basin-fill, volcanic units, and carbonate basement rocks.

  12. Microbial diversity of cryptoendolithic communities from the McMurdo Dry Valleys, Antarctica.

    Science.gov (United States)

    de la Torre, José R; Goebel, Brett M; Friedmann, E Imre; Pace, Norman R

    2003-07-01

    In the McMurdo Dry Valleys of Antarctica, microorganisms colonize the pore spaces of exposed rocks and are thereby protected from the desiccating environmental conditions on the surface. These cryptoendolithic communities have received attention in microscopy and culture-based studies but have not been examined by molecular approaches. We surveyed the microbial biodiversity of selected cryptoendolithic communities by analyzing clone libraries of rRNA genes amplified from environmental DNA. Over 1,100 individual clones from two types of cryptoendolithic communities, cyanobacterium dominated and lichen dominated, were analyzed. Clones fell into 51 relatedness groups (phylotypes) with > or =98% rRNA sequence identity (46 bacterial and 5 eucaryal). No representatives of Archaea were detected. No phylotypes were shared between the two classes of endolithic communities studied. Clone libraries based on both types of communities were dominated by a relatively small number of phylotypes that, because of their relative abundance, presumably represent the main primary producers in these communities. In the lichen-dominated community, three rRNA sequences, from a fungus, a green alga, and a chloroplast, of the types known to be associated with lichens, accounted for over 70% of the clones. This high abundance confirms the dominance of lichens in this community. In contrast, analysis of the supposedly cyanobacterium-dominated community indicated, in addition to cyanobacteria, at least two unsuspected organisms that, because of their abundance, may play important roles in the community. These included a member of the alpha subdivision of the Proteobacteria that potentially is capable of aerobic anoxygenic photosynthesis and a distant relative of Deinococcus that defines, along with other Deinococcus-related sequences from Antarctica, a new clade within the Thermus-Deinococcus bacterial phylogenetic division. PMID:12839754

  13. Habitat Range of two Alpine Medicinal Plants in a Trans-Himalayan Dry Valley, Central Nepal

    Institute of Scientific and Technical Information of China (English)

    Bharat Babu SHRESTHA; Pramod Kumar JHA

    2009-01-01

    Understanding of the habitat range of threatened Himalayan medicinal plants which are declining in their abundance due to high anthropogenic disturbances is essential for developing conservation strategies and agro-technologies for cultivation. In this communication, we have discussed the habitat range of two alpine medicinal plants, Aconitum naviculare (Briihl) Stapf and Neopierorhiza scrophulariiflora (Pennel) Hong in a trans-Himalayan dry valley of central Nepal, Manang district. They are the most prioritized medicinal plants of the study area in terms of ethnomedicinal uses. A. naviculare occurs on warm and dry south facing slopes between 4090-4650 m asl along with sclerophyllous and thorny alpine scrubs, while N. serophulariiflora is exclusively found on cool and moist north facing slope between 4o0o and 4400 m asl where adequate water is available from snow melt to create a suitable habitat for this wetland dependent species. The soil in rooting zone of the two plants differs significantly in organic carbon (OC), organic matter (OM), total nitrogen (N) and carbon to nitrogen (C/N) ratio. Due to cool and moist condition of N. scrophulariiflora habitat, accumulation of soil OC is higher, but soil N content is lower probably due to slow release from litter, higher leaching loss and greater retention in perennial live biomass of the plant. The C/N ratio of soil is more suitable in A. navuculare habitat than that of N scrophulariiflora for N supply. Warm and sunny site with N rich soft can be suitable for cultivation of A. naviculare, while moist and cool site with organic soil for N. scrophulariiflora. The populations of both the plants are fragmented and small. Due to collection by human and trampling damage by livestock, the population of A. naviculare was found absent in open areas in five of the six sampling sites and it was confined only within the bushes of alpine scrubs. For N. serophulariiflora, high probability of complete receding of small glaciers may

  14. X-ray Amorphous Phases in Antarctica Dry Valley Soils: Insight into Aqueous Alteration Processes on Mars?

    Science.gov (United States)

    Ming, D. W.; Morris, R. V.; Rampe, E. B.; Quinn, J. E.; Graff, T. G.

    2015-12-01

    The Chemistry and Mineralogy (CheMin) instrument onboard the Mars Curiosity rover has detected abundant amounts (approx. 25-30 wt. %) of X-ray amorphous materials in a windblown deposit (Rocknest) and in a sedimentary mudstone (Cumberland and John Klein) in Gale crater. On Earth, X-ray amorphous components are common in soils and sediments, but usually not as abundant as detected in Gale crater. One hypothesis for the abundant X-ray amorphous materials on Mars is limited interaction of liquid water with surface materials, kinetically inhibiting maturation to more crystalline phases. The objective of this study was to characterize the chemistry and mineralogy of soils formed in the Antarctica Dry Valleys, one of the driest locations on Earth. Two soils were characterized from different elevations, including a low elevation, coastal, subxerous soil in Taylor Valley and a high elevation, ultraxerous soil in University Valley. A variety of techniques were used to characterize materials from each soil horizon, including Rietveld analysis of X-ray diffraction data. For Taylor Valley soil, the X-ray amorphous component ranged from about 4 wt. % in the upper horizon to as high as 15 wt. % in the lowest horizon just above the permafrost layer. Transmission electron microscopy indicated that the presence of short-range ordered (SRO) smectite was the most likely candidate for the X-ray amorphous materials in the Taylor Valley soils. The SRO smectite is likely an aqueous alteration product of mica inherited from granitic materials during glaciation of Taylor Valley. The drier University Valley soil had lower X-ray amorphous contents of about 5 wt. % througout the profile. The X-ray amorphous materials in University Valley are attributed to nanoparticles of TiO2 and possibly amorphous SiO2. The high abundance of X-ray amorphous materials in Taylor Valley is surprising for one of the driest places on Earth. These materials may have been physically and chemical altered during

  15. Estimates of natural ground-water discharge and characterization of water quality in Dry Valley, Washoe County, West-Central Nevada, 2002-2003

    Science.gov (United States)

    Berger, David L.; Maurer, Douglas K.; Lopes, Thomas J.; Halford, Keith J.

    2004-01-01

    The Dry Valley Hydrographic Area is being considered as a potential source area for additional water supplies for the Reno-Sparks area, which is about 25 miles south of Dry Valley. Current estimates of annual ground-water recharge to Dry Valley have a considerable range. In undeveloped valleys, such as Dry Valley, long-term ground-water discharge can be assumed the same as long-term ground-water recharge. Because estimating ground-water discharge has more certainty than estimating ground-water recharge from precipitation, the U.S. Geological Survey, in cooperation with Washoe County, began a three-year study to re-evaluate the ground-water resources by estimating natural ground-water discharge and characterize ground-water quality in Dry Valley. In Dry Valley, natural ground-water discharge occurs as subsurface outflow and by ground-water evapotranspiration. The amount of subsurface outflow from the upper part of Dry Valley to Winnemucca and Honey Lake Valleys likely is small. Subsurface outflow from Dry Valley westward to Long Valley, California was estimated using Darcy's Law. Analysis of two aquifer tests show the transmissivity of poorly sorted sediments near the western side of Dry Valley is 1,200 to 1,500 square feet per day. The width of unconsolidated sediments is about 4,000 feet between exposures of tuffaceous deposits along the State line, and decreases to about 1,500 feet (0.5 mile) west of the State line. The hydraulic gradient east and west of the State line ranges from 0.003 to 0.005 foot per foot. Using these values, subsurface outflow to Long Valley is estimated to be 50 to 250 acre-feet per year. Areas of ground-water evapotranspiration were field mapped and partitioned into zones of plant cover using relations derived from Landsat imagery acquired July 8, 2002. Evapotranspiration rates for each plant-cover zone were multiplied by the corresponding area and summed to estimate annual ground-water evapotranspiration. About 640 to 790 acre-feet per

  16. Identifying elements in rocks from the Dry Valleys desert (Antarctica) by ion beam proton induced X-ray emission

    International Nuclear Information System (INIS)

    In some zones of Antarctica's cold and dry desert, the extinction of cryptoendolithic microorganisms leaves behind inorganic traces of microbial life. The extinction of these microorganisms is considered to be the best terrestrial analogue of the disappearance of possible life on early Mars. In the present study, sandstone rock samples from several sites of the Dry Valleys known to harbour endolithic microorganisms, as well as samples with microbial fossils, were analysed by proton induced X-ray emission (PIXE). Our findings suggest significant differences in major element concentrations among the different zones within the same sample. In some sample fractions, these differences could be considered as traces of the microbial origin. However, other samples reveal contamination produced by allochthonous minerals of abiogenetic origin

  17. Continuous Nanoclimate Data (1985-1988) from the Ross Desert (McMurdo Dry Valleys) Cryptoendolithic Microbial Ecosystem

    Science.gov (United States)

    McKay, Christopher P.; Nienow, James; Meyer, Michael A.; Friedmann, E. Imre

    1993-01-01

    We have collected year-round nanoclimate data for the cryptoendolithic microbial habitat in sandstones of the Ross desert, Antarctica, obtained with an Argos satellite data system. Data for two sites in the McMurdo Dry Valleys are available: Linnaeus Terrace, January 1985 to June 1988, and Battleship Promontory, 1986-1987. The focus of this research is ecological, and hence year-round environmental data have been obtained for the ambient environment as well as for conditions within the rock. Using data from the summer, we compare the conditions inside the rock to the outside weather. This demonstrates how the rock provides a shelter for the endolithic microbial community. The most important property of the rock is that it absorbs the summer sunlight, thereby warming up to temperatures above freezing. This warming allows snowmelt to seep into the rock, and the moisture level in the rocks can remain high for weeks against loss to the dry environment.

  18. Nutrient treatments alter microbial mat colonization in two glacial meltwater streams from the McMurdo Dry Valleys, Antarctica.

    Science.gov (United States)

    Kohler, Tyler J; Van Horn, David J; Darling, Joshua P; Takacs-Vesbach, Cristina D; McKnight, Diane M

    2016-04-01

    Microbial mats are abundant in many alpine and polar aquatic ecosystems. With warmer temperatures, new hydrologic pathways are developing in these regions and increasing dissolved nutrient fluxes. In the McMurdo Dry Valleys, thermokarsting may release both nutrients and sediment, and has the potential to influence mats in glacial meltwater streams. To test the role of nutrient inputs on community structure, we created nutrient diffusing substrata (NDS) with agar enriched in N, P and N + P, with controls, and deployed them into two Dry Valley streams. We found N amendments (N and N + P) to have greater chlorophyll-a concentrations, total algal biovolume, more fine filamentous cyanobacteria and a higher proportion of live diatoms than other treatments. Furthermore, N treatments were substantially elevated in Bacteroidetes and the small diatom, Fistulifera pelliculosa. On the other hand, species richness was almost double in P and N + P treatments over others, and coccoid green algae and Proteobacteria were more abundant in both streams. Collectively, these data suggest that nutrients have the potential to stimulate growth and alter community structure in glacial meltwater stream microbial mats, and the recent erosion of permafrost and accelerated glacial melt will likely impact resident biota in polar lotic systems here and elsewhere. PMID:26940086

  19. Analysis of vegetation dynamics and phytodiversity from three dry deciduous forests of Doon Valley, Western Himalaya, India

    Directory of Open Access Journals (Sweden)

    Gautam Mandal

    2014-09-01

    Full Text Available The present study aimed to analyze the vegetation dynamics and plant diversity from the dry deciduous forests of Doon Valley. Species richness, regeneration, and change in community composition of these forests were studied and change was noticed with Shorea robusta as the main dominant species, and Mallotus philippensis, Syzygium cumini, and Ehretia laevis as codominant tree species in all communities. The highest species richness and diversity rates were found to be increased with the decrease in tree density and basal area. The high Importance Value Index recorded in Thano (>150 indicates that the S. robusta forest is progressing toward the culmination stage, whereas the lower IVI values (100 and 150 in the other two sites (Selaqui – Jhajra and Asarori signify the heavy disturbance of these sites and further establishment of alien invasive species such as Cassia tora, Cassia occidentalis, Lantana camara, Urena lobata, Ipomoea carnea, Sida acuta, and Solanum torvum.

  20. Comments on the Regional Climate Variability Driven by Foehn Winds in the McMurdo Dry Valleys, Antarctica

    CERN Document Server

    Sienicki, Krzysztof

    2013-01-01

    The main objection to Speirs, McGowan, Steinhoff and Bromwich work arises from the lack of analyses of the probability distribution functions of underlying processes leading to wind formation of which velocities are measured by automated weather stations and reported in the paper. Mathematically a rigorous definition of calculating the correlation coefficient (Pearson product-moment correlation coefficient) of averages does not exist. Therefore the authors numbers as given in Table II represent a set of randomly calculated figures. The authors suggestion in relation to a few of these random numbers that some of them have statistical significance at the 95% level is erroneous since no relationship exists between correlation coefficient of averages and statistical significance. Therefore Speirs et al. main conclusion that the - SAM is found to significantly influence foehn wind frequency at McMurdo Dry Valleys is unfounded.

  1. Soil erosion risk evaluation using GIS in the Yuanmou County,a dry-hot valley of Yunnan, China

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Soil erosion is a major threat to sustainable agriculture. Evaluating regional erosion risk is increasingly needed by national and in-ternational environmental agencies. This study elaborates a model (using spatial principal component analysis [SPCA]) method for the evaluation of soil erosion risk in a representative area of dry-hot valley (Yuanmou County) at a scale of 1:100,000 using a spatial database and GIS. The model contains seven factors: elevation, slope, annual precipitation, land use, vegetation, soil, and population density. The evaluation results show that five grades of soil erosion risk: very low, low, medium, high, and very high. These are divided in the study area, and a soil erosion risk evaluation map is created. The model may be applicable to other areas of China because it utilizes spatial data that are generally available.

  2. Late-glacial and Holocene history of the dry forest area in the south Colombian Cauca Valley

    Science.gov (United States)

    Berrío, Juan Carlos; Hooghiemstra, Henry; Marchant, Robert; Rangel, Orlando

    2002-10-01

    Two sedimentary cores with pollen, charcoal and radiocarbon data are presented. These records document the Late-glacial and Holocene dry forest vegetation, fire and environmental history of the southern Cauca Valley in Colombia (1020 m). Core Quilichao-1 (640 cm; 3° 6N, 76° 31W) represents the periods of 13 150-7720 14C yr BP and, following a hiatus, from 2880 14C yr BP to modern. Core La Teta-2 (250 cm; 3° 5N, 76° 32W) provides a continuous record from 8700 14C yr BP to modern.Around 13 150 14C yr BP core Quilichao-1 shows an active Late-glacial drainage system and presence of dry forest. From 11 465 to 10 520 14C yr BP dry forest consists mainly of Crotalaria, Moraceae/Urticaceae, Melastomataceae/Combretaceae, Piper and low stature trees, such as Acalypha, Alchornea, Cecropia and Celtis. At higher elevation Andean forest comprising Alnus, Hedyosmum, Quercus and Myricachanged, with extensive open grass vegetation indicative of dry climatic conditions. This event may coincide with the change to cool and dry conditions in the second part of the El Abra stadial, an equivalent to the Younger Dryas. From 8850 climatic conditions relative to the present, these prevailing up to 2880 dry forest reached maximum expansion. Dry forest was gradually replaced by grassy vegetation, reaching maximum expansion around 2300

  3. USING INTERNAL RADIO TRANSMITTERS TO DETERMINE THE BEHAVIORAL RESPONSE OF BULLFROGS, RANA CATESBEIANA, TO SEASONAL POND DRYING IN THE WILLAMETTE VALLEY, OREGON

    Science.gov (United States)

    We implanted radio tags in adult bullfrogs from three ponds located in a Willamette Valley game reserve to determine their behavior and habitat use as the ponds dried during late summer. We used radio telemetry and a Global Position System (GPS) to locate and record the position ...

  4. 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.

  5. 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. PMID:24782842

  6. Rodent consumption by Philodryas psammophidea (Serpentes: Colubridae), from the Inter-andean Dry Valleys of Central Bolivia

    OpenAIRE

    Quinteros Muñoz, Oliver; Peñaranda, Diego A.; Navarro, Freddy

    2010-01-01

    In May 18, 2009 we found an adult female of Philodryas psammophidea (930 mm SVL), at a side of a crop field in the Tabacal valley (18º23’7.42” S – 64º38’7.88”W, 2015 m), Narciso Campero province southern Cochabamba, Bolivia. Ecologically, this valley belongs to the Inter-Andean Dry Forests of Bolivia. In the stomach of thesnake probably killed by a settler, therewas an adult female of Graomys domorum (Phyllotini; Sigmodontidae), a native rodent species widely distributed in the region....

  7. Laser Induced Fluorescence Imaging: Searching for Organics from the Dry Valleys of Queen Maud Land Antarctica to the Regolith and Ices of Mars

    Science.gov (United States)

    Storrie-Lombardi, M. C.; Sattler, B.; Muller, J.-P.; Fisk, M.; Cousins, C.; Dartnell, L.

    2009-04-01

    Laser induced fluorescence imaging using excitation in ultraviolet (UV) wavelengths has been proposed as a nondestructive astrobiological rapid survey tool to search for amino and nucleic acids [1], microbial life [2], and polycyclic aromatic hydrocarbons (PAHs) deep in the Mars regolith [3, 4]. However, the technique is easily adapted to search for complex biomolecular targets using longer wavelength sources [5]. Of particular interest is the ability of excitation at 532 nm to detect photosynthetic pigments in cyanobacteria-dominated microbial communities populating the ice of alpine, Arctic, and Antarctic lakes, glaciers, and ice sheets [6-8]. During the months of November and December 2008 we tested the technique as part of an extended international, interdisciplinary field campaign in the Dry Valleys of Schirmacher Oasis and Lake Untersee, Queen Maud Land, Antarctica. In this paper we review our recent laboratory experiments on the use of UV excitation for detection of PAHs doped on Mars analogue soils [9] and chasmo- and epilithic lichen communities within basaltic Iceland lavas. We present for the first time the results of our field experiments conducted during the Tawani 2008 International Antarctic Expedition for in situ detection and quantification of photosynthetic biomass in the ice caps of annual and perennially ice-covered Antarctic lakes. We discuss the advantages of using a nondestructive rapid survey photonic tools such as laser induced fluorescence imaging that can be easily implemented from lander, rover, airborne, or orbital platforms. The techniques presented can be utilized to monitor the microbial potential of large, critical ecosystems on Earth, or to facilitate the remote or manned search for organics and photosynthetic life on any terrestrial planet. References 1. Storrie-Lombardi, M.C., Hug, W.F., McDonald, G.D., Tsapin, A.I., and Nealson, K.H. 2001. Hollow cathode ion lasers for deep ultraviolet Raman spectroscopy and fluorescence imaging

  8. Using micro-isotopic approaches to evaluate the origin and emplacement mechanism of the Basement Sill, Dry Valleys, Antarctica

    Science.gov (United States)

    Davidson, J. P.; Jerram, D.; Petford, N.; Marsh, B.

    2005-12-01

    Isotopic fingerprinting of mineral phases in volcanic rocks has been successfully employed recently to track magma evolution and to identify populations from different sources. Integration of this approach with textural characterisation allows chemical evolution to be integrated with physical changes (growth, nucleation, mixing). In plutonic rocks this approach has been shown to be valid, despite the potential for isotopic re-equilibration during more protracted cooling than volcanic rocks. In fact, the degree of isotopic reequilibration can be used to constrain the cooling rate of the rock, which, in turn, relates to the emplacement history. At the Rum layered mafic intrusion, NW Scotland, isotopically distinct plagioclase cores and rims suggest relatively rapid cooling (at the scale of an individual layer) of the order 0.1°C per year, consistent with sill-like emplacement. The origin of isotopic variation is consistent with growth from a progressively contaminated magma prior to transport and deposition. The Basement Sill of the Dry Valleys Complex, Antarctica, contains an opx-rich tongue claimed to be emplaced as a crystal mush into a crystal-poor magmatic envelope. Given the broadly similar dimensions and compositions of the Rum Intrusion and Basement Sill we expect to be able to use micro-isotopic analyses of cumulus plagioclase crystals in the opx tongue to a) determine whether the magmatic source is the same as the rest of the sill, b) constrain the effects of contamination during crystal growth and emplacement and c) constrain cooling pathways

  9. Antarctic Miocene Climate

    Science.gov (United States)

    Ashworth, A. C.; Lewis, A. R.

    2013-12-01

    Fossils from Antarctic Miocene terrestrial deposits, coupled with stratigraphic, geochemical and paleontological data from marine boreholes, provide new insights into the climatic history of the continent. During the Miocene, ice caps coalesced to form ice sheets and vegetated surfaces gave way to barren expanses. The cryospheric changes especially have global climatic implications. The fossil data consists of diatoms, pollen and spores, and macroscopic remains of plants, ostracods, insects, molluscs and a fish. Plant fossils include wood and leaves of Nothofagus (southern beech), seeds of several vascular plants, including Ranunculus (buttercup), Hippuris (mare's-tail) and Myriophyllum (watermilfoil), megaspores of Isoetes (quillwort), and moss species. The insect chitin consists of larval head capsules of Chironomidae (midges) and exoskeletal parts of Coleoptera (beetles). The molluscs include freshwater gastropods and bivalves. The majority of these taxa are likely descendants of taxa that had survived on the continent from the Paleogene or earlier. Even though early Miocene glaciations may have been large, the climate was never cold enough to cause the extinction of the biota, which probably survived in coastal refugia. Early Miocene (c. 20 Ma) macrofossils from the McMurdo Dry Valleys (77°S) support palynological interpretations from the Cape Roberts and ANDRILL marine records that the upland vegetation was a shrub tundra. Mean summer temperature (MST) in the uplands was c. 6°C and possibly higher at the coast. The climate was wet, supporting mires and lakes. By the mid-Miocene, even though the climate continued to be wet. MST was c. 4°C which was too cold to support Nothofagus and most vascular plant species. Stratigraphic evidence indicates that the time between the Early and Mid-Miocene was a time of repeated ice advances and retreats of small glaciers originating from ice caps. At c. 14 Ma there appears to have been a modal shift in climate to

  10. Nitrogen Mineralization of Prunings of Six N2-Fixing Hedgerow Species in a Dry Valley of the Jinsha River

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A litterbag experiment of 12 weeks was conducted to study nitrogen mineralization process of prunings of six nitrogen-fixing hedgerow species in a dry valley of the Jinsha River. Prunings were incorporated into soil or used as mulch. The results indicated that pruning N of the six hedgerow species was mineralized fast in the first week and then decreased slowly in the rest of the study period. When prunings were incorporated into soil, the amount of nitrogen mineralized by the end of the first week accounted for 69.9%, 58.2%, 54.5%,43.0%, 29.6% and 20.6% of the total N in prunings of Desmodium rensonii, Tephrosia candida, Leucaena leucocuphala, Albizia yunnanensis, Acacia dealbata, and Acacia mearnsii, respectively. When prunings of L. leucocephala were used as mulch materials, the amount of nitrogen mineralized in the first week was 16.2% less than that of prunings incorporated into soil. The mineralization pattern of pruning N could be simulated by an exponent model Nt% = N01% (1 - exp(-k1t))+ N02% (1 - exp(-k2t)) where Nt% is cumulative mineralized N in time t, N01% and N02 % are readily and less readily mineralizable N in prunings,respectively, and k1 and k2 are rate constants. A half-life period of pruning nitrogen mineralization could ~ be determined by this model. The nitrogen content in the pruning residues decreased quickly in the first week but fluctuated thereafter. The initial C/N ratio was negatively related to the mineralization rate of prunings.``

  11. Early performance of Pinus radiata provenances in the earthquake-ravaged dry river valley area of Sichuan, southwest China

    Institute of Scientific and Technical Information of China (English)

    Huiquan Bi; Rongwei Li; Zongxing Wu; Quan Huang; Qianli Liu; Yongli; Zhou Yun Li

    2013-01-01

    A provenance experiment involving five native provenances and an Australian landrace of Pinus radiata (D. Don) was established over three sites in the dry river valley area of Sichuan, southwest China in 2004 in order to select the most suitable provenance for environmental planting on the dry, steep and degraded slopes to reduce soil erosion. Although with much lower soil moisture supply and mean minimum temperatures in winter compared to P. radiata provenance trials estab-lished elsewhere in the world, these sites are within the working limits of the species defined by previous climate modelling and matching. Be-cause of the difficult site conditions and severe natural disturbances after the experiment was established, mortality was high across the three sites in comparison to provenance trials in other countries. The average mor-tality rate among the provenance by replicate planting units over the three sites varied from 16% to 76% four years after planting, and from 40%to 88%five years after planting . The repeated measurements of tree size over time were analysed using multilevel linear mixed models to derive growth curves for the mean, median, the 75th and the 90th percen-tiles of the size distribution of each provenance at each site. There were significant site effects on tree growth, but no significant interactions between site and provenance was detected. Among the six provenances, Cambria was the best performer in diameter, height and stem volume growth across all sites. The better than average and the best trees of this provenance, as represented by the 75th and 90th percentiles of the nomi-nal stem volume distribution, were significantly larger than the Austra-lian landrace, Año Nuevo, and the two island provenances, Guadalupe and Cedros. Monterey was overall the second best performer behind Cambria. The Australian landrace, Guadalupe and Año Nuevo had simi-lar performances in general. Cedros was significantly and consistently inferior to all other

  12. Morphogenesis of Antarctic Paleosols: Martian Analogue

    Science.gov (United States)

    Mahaney, W. C.; Dohm, J. M.; Baker, V. R.; Newsom, Horton E.; Malloch, D.; Hancock, R. G. V.; Campbell, Iain; Sheppard, D.; Milner, M. W.

    2001-11-01

    Samples of horizons in paleosols from the Quartermain Mountains of the Antarctic Dry Valleys (Aztec and New Mountain areas) were analyzed for their physical characteristics, mineralogy, chemical composition, and microbiology to determine the accumulation and movement of salts and other soluble constituents and the presence/absence of microbial populations. Salt concentrations are of special interest because they are considered to be a function of age, derived over time, in part from nearby oceanic and high-altitude atmospheric sources. The chemical composition of ancient Miocene-age paleosols in these areas is the direct result of the deposition and weathering of airborne-influxed salts and other materials, as well as the weathering of till derived principally from local dolerite and sandstone outcrops. Paleosols nearer the coast have greater contents of Cl, whereas near the inland ice sheet, nitrogen tends to increase on a relative basis. The accumulation and vertical distribution of salts and other soluble chemical elements indicate relative amounts of movement in the profile over long periods of time, in the order of several million years. Four of the six selected subsamples from paleosol horizons in two ancient soil profiles contained nil concentrations of bacteria and fungi. However, two horizons at depths of between 3 and 8 cm, in two profiles, yielded several colonies of the fungi Beauveria bassiana and Penicillium brevicompactum, indicating very minor input of organic carbon. Beauveria bassiana is often reported in association with insects and is used commercially for the biological control of some insect pests. Penicillium species are commonly isolated from Arctic, temperate, and tropical soils and are known to utilize a wide variety of organic carbon and nitrogen compounds. The cold, dry soils of the Antarctic bear a close resemblance to various present and past martian environments where similar weathering could occur and possible microbial populations

  13. Anthropogenic Impacts on the Sediment Flux in the Dry-hot Valleys of Southwest China-an Example of the Longchuan River

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yue; LU Xixi; HUANG Ying; ZHU Yunmei

    2004-01-01

    The sediment flux data, measured from a dry-hot valley of the Longchuan River, a tributary of the lower Jinsha River, were analyzed with Mann-Kendall test, Seasonal Mann-Kendall test and Sen's test. In both the upper reaches (Xiaohekou) and the lower reaches (Xiaohuangguayuan), the sediment fluxes showed a significant increase from 1970 to 2001, despite the fact that the water discharge did not change significantly during the period and numerous reservoir constructions which contribute to the trap of sediment. This can be attributed to the intensification of human activities, especially the activities related to land surface disturbances such as deforestation and afforestation, expansion of agriculture land, and road constructions. This increase is more significant in the lower reaches of the river observed at the place of Xiaohuangguayuan due to the dry-hot climate. The profound increase in sediment flux has significant implications for effective management of the sedimentation problems of the on-going Three Gorges Reservoir.

  14. Adapting to climate change for food security through supplementary irrigation and changing sowing dates in the Rift Valley dry lands of Ethiopia

    Science.gov (United States)

    Muluneh Bitew, Alemayehu; Stroosnijder, Leo; keesstra, Saskia

    2015-04-01

    Studies on climate impacts and related adaptation strategies are increasingly becoming important to counteract the negative effects of climate change. In Ethiopia, climate change is likely to affect crop yields negatively. However, quantitative evidence is lacking about the ability of farm level adaptation options to offset negative impacts on food security. The MarkSimGCM weather generator was used to generate projected daily rainfall and temperature data originally taken from ECHAM5 general circulation model and ensemble mean of six models under A2 (high) and B1 (low) emission scenarios. We validated the FAO AquaCrop model and subsequently used it to predict maize yields and explore three adaptations options. Increasing plant density has the least effect on maize yield so that the density that is currently used by 'good' farmers (30,000) is recommended. The optimum level of supplemental irrigation (SI), in combination with this plant density, is application of SI when the percentage of soil water depletion reached 75% of the maximum available water in the root zone. In the future, dry spells during the Belg season increase and this has a negative effect on maize production. The predicted lower maize production due to the changing rainfall is only partly compensated by the expected increase in CO2 concentration. The shifting of sowing period of maize from the current Belg season (mostly April or May) to the first month of Kiremt season (June) can offset the predicted yield reduction caused by climate change. SI has a marginal effect in good rainfall years but using 94-111 mm of SI can avoid total crop failure in drought years. Hence, SI is an interesting option to improve food security in the Rift Valley dry lands of Ethiopia. Key words: Adaptation; Climate change; Central Rift Valley; Dry spell; Supplemental irrigation.

  15. Late glacial and Holocene history of the dry forest area in south Colombian Cauca Valley from sites Quilichao and la Teta

    International Nuclear Information System (INIS)

    Two sedimentary cores with records of pollen and charcoal content within a chronology provided by radiocarbon are presented from the southern Cauca Valley in Colombia (1020 m). These records document the late glacial and Holocene dry forest vegetation, fire and environment history. Specifically, core Quilichao -1 (640 cm; 3 degrade 6' N, 76 degrade 31' W) represents the periods of 13/150-7720 14C yr BP and following a hiatus from 2880 14C yr BP to recent. Core la Teta - 2 (250 cm; 3 degrade 5' N, 76 degrade 32' W) provides a record from 8700 14C yr BP around 13/150 214C yr BP Quilichao shown an active late glacial drainage system and presence of dry forest. From 11/465-10/520 14C yr BP dry forest consists mainly of Crotalaria Moraceae Urticaceae, Melastomataceae, Piper and low stature trees, such as Acalypha, Alchornea, Cecropia and Celtis. At higher elevation on the slopes Andean forest with Quercus, Hedyosmum, Myrica and Alnus are common

  16. Life Detection and Characterization of Subsurface Ice and Brine in the McMurdo Dry Valleys Using an Ultrasonic Gopher: A NASA ASTEP Project

    Science.gov (United States)

    Doran, P. T.; Bar-Cohen, Y.; Fritsen, C.; Kenig, F.; McKay, C. P.; Murray, A.; Sherrit, S.

    2003-01-01

    Evidence for the presence of ice and fluids near the surface of Mars in both the distant and recent past is growing with each new mission to the Planet. One explanation for fluids forming springlike features on Mars is the discharge of subsurface brines. Brines offer potential refugia for extant Martian life, and near surface ice could preserve a record of past life on the planet. Proven techniques to get underground to sample these environments, and get below the disruptive influence of the surface oxidant and radiation regime, will be critical for future astrobiology missions to Mars. Our Astrobiology for Science and Technology for Exploring Planets (ASTEP) project has the goal to develop and test a novel ultrasonic corer in a Mars analog environment, the McMurdo Dry valleys, Antarctica, and to detect and describe life in a previously unstudied extreme ecosystem; Lake Vida (Fig. 1), an ice-sealed lake.

  17. Isolation and Characterization of Microsatellite Loci for Hibiscus aridicola (Malvaceae, an Endangered Plant Endemic to the Dry-Hot Valleys of Jinsha River in Southwest China

    Directory of Open Access Journals (Sweden)

    Kaiyun Guan

    2011-09-01

    Full Text Available Hibiscus aridicola (Malvaceae is an endangered ornamental shrub endemic to the dry-hot valleys of Jinsha River in southwest China. Only four natural populations of H. aridicola exist in the wild according to our field investigation. It can be inferred that H. aridicola is facing a very high risk of extinction in the wild and an urgent conservation strategy is required. By using a modified biotin-streptavidin capture method, a total of 40 microsatellite markers were developed and characterized in H. aridicola for the first time. Polymorphisms were evaluated in 39 individuals from four natural populations. Fifteen of the markers showed polymorphisms with two to six alleles per locus; the observed heterozygosity ranged from 0.19 to 0.72. These microsatellite loci would be useful tools for population genetics studies on H. aridicola and other con-generic species which are important to the conservation and development of endangered species.

  18. Ciliated protozoa of two antarctic lakes: analysis by quantitative protargol staining and examination of artificial substrates

    Science.gov (United States)

    Kepner, R. L. Jr; Wharton, R. A. Jr; Coats, D. W.; Wharton RA, J. r. (Principal Investigator)

    1999-01-01

    Planktonic and artificial substrate-associated ciliates have been identified in two perennially ice-covered antarctic lakes of the McMurdo Dry Valleys. Abundances estimated by quantitative protargol staining ranged from < 5 to 31690 cells l-1, levels that are comparable to those previously obtained using other methods. Nineteen ciliate taxa were identified from these lakes, with the most frequently encountered genera being Plagiocampa, Askenasia, Monodinium, Sphaerophrya and Vorticella. The taxonomic findings compare favorably with those of previous investigators; however four previously unreported genera were observed in both Lakes Fryxell and Hoare. The variability in the depth distributions of ciliates in Lake Fryxell is explained in terms of lake physicochemical properties and ciliate prey distributions, while factors related to temporal succession in the Lake Hoare assemblage remain unexplained. Local marine or temperate zone freshwater habitats are a more likely source than the surrounding dry valleys soils for present ciliate colonists in these lakes. Although the taxonomic uncertainties require further examination, our results suggest that ciliate populations in these antarctic lakes undergo significant fluctuations and are more diverse than was previously recognized.

  19. [Characteristics of carbon sequestration and apparent stability of new sequestered carbon in forested torrid red soil at dry-hot valley].

    Science.gov (United States)

    Tang, Guo-Yong; Li, Kun; Sun, Yong-Yu; Zhang, Chun-Hua

    2012-02-01

    Great concerns about potential for carbon (C) sequestration in forested soil and the stability of the sequestered C have been exerted under the background of global climate change. Organic C density in soil and in soil physical and biochemical fractions at various stages (1991, 1997, 2003 and 2010) in Acacia auriculiformis stand afforested in 1991 were investigated at Dry-Hot Valley via density fractionation and acid hydrolysis. The results showed that organic C density at surface (0-15 cm) and subsurface (15-30 cm) soil layers was 1.40 kg x m(-2) and 0.99 kg x m(-2) after 19 years of afforestation, respectively. The annual C sequestration rates of surface and subsurface soil layers were 37.89 g x (m2 x a)(-1) and 16.84 g x (m2 x a)(-1) during 1991-2010, respectively, and the sequestration was accelerating. The ratio of organic C in heavy fraction to in surface soil was 71.44% in 2003, which was significantly higher than that in 2010 (67.99%). The recalcitrant carbon index (I(RC)) in light fraction was significantly higher than that in heavy fraction at surface or subsurface layers in 2003, but both decreased with aging of plantation, especially I(RC) in light fraction. Approximately 57% - 70% of new sequestered C was protected by physical mechanism and 33-49 percent was biochemical recalcitrant C during the stage from 12 to 19 years after afforestation. The results reveal that forested torrid red soil at Dry-Hot Valley may have a considerable capability of C sequestration. The biochemical stability of physically protected C is lower than the unprotected. Both the stability, however, decreases with the plantation age. PMID:22509596

  20. Antarctic lakes (above and beneath the ice sheet): Analogues for Mars

    Science.gov (United States)

    Rice, J. W., Jr.

    The perennial ice covered lakes of the Antarctic are considered to be excellent analogues to lakes that once existed on Mars. Field studies of ice covered lakes, paleolakes, and polar beaches were conducted in the Bunger Hills Oasis, Eastern Antarctica. These studies are extended to the Dry Valleys, Western Antarctica, and the Arctic. Important distinctions were made between ice covered and non-ice covered bodies of water in terms of the geomorphic signatures produced. The most notable landforms produced by ice covered lakes are ice shoved ridges. These features form discrete segmented ramparts of boulders and sediments pushed up along the shores of lakes and/or seas. Sub-ice lakes have been discovered under the Antarctic ice sheet using radio echo sounding. These lakes occur in regions of low surface slope, low surface accumulations, and low ice velocity, and occupy bedrock hollows. The presence of sub-ice lakes below the Martian polar caps is possible. The discovery of the Antarctic sub-ice lakes raises possibilities concerning Martian lakes and exobiology.

  1. Antarctic snow and global climate

    International Nuclear Information System (INIS)

    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

  2. 西南地区的干热河谷及其森林培育%The dry-hot valleys and forestation in southwest china

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The dry-hot valleys (DHV) are located mainly in the deeply incised valleys along the upper streams of several international and domestically rivers, like Yangtz, Zhu, Lanchang, Hong, and Nu rivers. This paper briefly described the reasons of formation of DHV from view of climate and geographical conditions, and by referring to great deal of documents, analyzed the historical case and present status of the vegetations in DHV. The environment in DHV is facing the serious vulnerable period in the history due to its nature situation of half-year dry period, fragile geological structure and shallow soil, and its social situation of over dense population and over farming. The primary vegetation is broad leaf forest and it was denuded in the history. The current local vegetation is the degraded secondary vegetation: savanna and succulent thorny shrub. Since the environmental situation in valley influenced directly the water body of river, the soil erosion control and re-vegetation in DHV is the most urgent task in the process of environmental harness along the rivers. Quite a few pilot research projects have been carried out.on demonstrating new silviculture techniques for re-vegetation in DHV, but there still exist great difficulties in carrying out large-scale afforestation engineering.%干热河谷主要分布于长江、珠江、澜沧江、红河和怒江等国内和国际性河流的上游深切河谷地段。本文对干热河谷形成的地理和气候原因进行了阐述,并通过引证大量文献,分析了干热河谷植被的历史情况和现状。由于干热河谷地区的地质结构不稳定、土层浅薄、人口膨胀、过度耕种,尤其长达半年的旱季等原因,导致该地区的生态环境处于极端的脆弱阶段。当地的原始植被为常绿阔叶林和落叶阔叶林,但均遭到严重的破坏。现有植被为次生的稀树草坡和肉质化刺灌木。由于干热河谷的植被情况直接影响河流水体的质量

  3. Underestimated endemic species diversity in the dry inter-Andean valley of the Río Marañón, northern Peru: An example from Mimosa(Leguminosae, Mimosoideae)

    OpenAIRE

    Särkinen, T E; Marcelo-Peña, J L; Yomona, A D; Simon, M. F.; Pennington, T P; Hughes, C E

    2011-01-01

    Molecular phylogenies which include multiple accessions of species and near complete taxon sampling can be an important tool for estimating species diversity when used in combination with traditional morphology-based taxonomy. Here we use a densely sampled plastid gene tree for a morphologically complex group within the legume genus Mimosa (sect. Batocaulon ser. Andinae) to improve estimates of species limits and diversity in the poorly known dry inter-Andean valley of the Río Marañón, northe...

  4. Improved High-Quality Draft Genome Sequence of the Eurypsychrophile Rhodotorula sp. JG1b, Isolated from Permafrost in the Hyperarid Upper-Elevation McMurdo Dry Valleys, Antarctica.

    Science.gov (United States)

    Goordial, Jacqueline; Raymond-Bouchard, Isabelle; Riley, Robert; Ronholm, Jennifer; Shapiro, Nicole; Woyke, Tanja; LaButti, Kurt M; Tice, Hope; Amirebrahimi, Mojgan; Grigoriev, Igor V; Greer, Charles; Bakermans, Corien; Whyte, Lyle

    2016-01-01

    Here, we report the draft genome sequence of Rhodotorula sp. strain JG1b, a yeast that was isolated from ice-cemented permafrost in the upper-elevation McMurdo Dry Valleys, Antarctica. The sequenced genome size is 19.39 Mb, consisting of 156 scaffolds and containing a total of 5,625 predicted genes. This is the first known cold-adapted Rhodotorula sp. sequenced to date. PMID:26988035

  5. Testing oils in antarctic soils

    International Nuclear Information System (INIS)

    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

  6. Miocene Antarctic Terrestrial Realm

    Science.gov (United States)

    Ashworth, A. C.; Lewis, A.; Marchant, D. R.

    2009-12-01

    The discovery of several locations in the Transantarctic Mountains that contain macrofossils and pollen is transforming our understanding of late Cenozoic Antarctica. The most southerly location is on the Beardmore Glacier (85.1°S) about 500 km from the South Pole. The environment was an active glacial margin in which plants, insects and freshwater mollusks inhabited the sand and gravel bars and small lakes on an outwash plain. In addition to leaves and wood of dwarf Nothofagus (Southern Beech) shrubs, achenes of Ranunculus (Buttercup), in situ cushion growth forms of mosses and a vascular plant, the assemblages contains various exoskeletal parts of carabid and curculionid beetles and a cyclorrhaphan fly, the shells of freshwater bivalve and gastropod species and a fish tooth. Initially the deposits were assigned a Pliocene age (3.5 Ma) but a mid- to early Miocene age is more probable (c. 14 - 25 Ma) based on correlation of fossil pollen from the deposits with 39Ar/40Ar dated pollen assemblages from the McMurdo Dry Valleys locations. The oldest location within the Dry Valleys also involved an active ice margin but was part of a valley system that was completely deglaciated for intervals long enough for thick paleosols to develop. The Friis Hills fossil deposits of the Taylor Valley region (77.8°S) are at least 19.76 Ma based on the 39Ar/40Ar age of a volcanic ash bed. The valley floor during the non-glacial phases had poorly-drained soils and the extensive development of mossy mires. Wood and leaves of Nothofagus are abundant in lacustrine deposits. The silts of shallow fluvial channels contain abundant megaspores and spiky leaves of the aquatic lycopod Isoetes (Quillwort). Fossils of beetles are also present in these deposits. During the glacial phases, proglacial lakes were surrounded by dwarfed, deciduous Nothofagus shrubs. The youngest fossils recovered from the Dry Valleys are from the Olympus Range (77.5°S) with an age of 14.07 Ma. The environment was an

  7. New insights into the origin and evolution of Lake Vida, McMurdo Dry Valleys, Antarctica — A noble gas study in ice and brines

    Science.gov (United States)

    Malone, Jessica L.; Castro, M. Clara; Hall, Chris M.; Doran, Peter T.; Kenig, Fabien; McKay, Chris P.

    2010-01-01

    Unlike other lakes in the McMurdo Dry Valleys, Antarctica, Lake Vida has a thick (~ 19 m) ice cover sealing a liquid brine body of unusually high salinity (~ 245 g/L) from the atmosphere. To constrain the conditions under which the atypical Lake Vida ice cover formed and evolved, 19 ice samples were collected down to a depth of ~ 14 m, together with three brine samples trapped in the ice at ~ 16 m for analysis of helium, neon, argon, krypton, and xenon concentrations. The broad pattern of noble gas concentrations for Lake Vida samples is fundamentally different from that of air saturated water (ASW) at 0 °C and an elevation of 340 m for salinities of 0 (ice) and 245 g/L (brine). Overall, ice samples are enriched in He and depleted in Ne with saturation relative to ASW averages of 1.38 and 0.82, respectively, and strongly depleted in Ar, Kr, and Xe with relative saturations of 0.10, 0.06, and 0.05, respectively. By contrast, brine samples are generally depleted in He and Ne (relative saturation averages of 0.33 and 0.27, respectively) but enriched in Ar, Kr, and Xe, with relative saturation averages of 1.45, 3.15, and 8.86, respectively. A three-phase freezing partitioning model generating brine, ice and bubble concentrations for all stable noble gases was tested and compared with our data. Measured brine values are best reproduced for a salinity value of 175 g/L, a pressure of 1.1 atm, and a bubble volume of 20 cm 3 kg -1. Sensitivity tests for ice + bubble samples show an ideal fit for bubble volumes of ~ 1-2 cm 3 kg -1. Our results show that the conditions under which ice and brine formed and evolved at Lake Vida are significantly different from other ice-covered lakes in the area. Our brine data suggest that Lake Vida may be transitioning from a wet to a dry-based lake, while the ice + bubble data suggest at least partial re-equilibration of residual liquid with the atmosphere as ice forms at the top of Lake Vida ice cover.

  8. Microbiology and Geochemistry of Antarctic Paleosols

    Science.gov (United States)

    Mahaney, W. C.; Malloch, D.; Hancock, R. G. V.; Campbell, I. B.; Sheppard, D.

    2000-08-01

    Samples of ancient soils from horizons in paleosols from the Quartermain Mountains (Aztec and New Mountain areas of the Antarctic Dry Valleys) were analyzed for their chemical composition and microbiology to determine the accumulation and movement of salts and other soluble constituents. The salt concentrations are of special interest because they are considered to be a function of age, derived in part from nearby oceanic and high altitude atmospheric sources. The geochemistry of ancient Miocene-age paleosols in these areas is the direct result of the deposition and weathering of till, derived principally from dolerite and sandstone source rock, in association with airborne-influxed salts. Paleosols nearer the coast have greater contents of chlorine, and farther inland near the Inland Ice Sheet, nitrogen tends to increase on a relative basis. The accumulation and vertical distribution of salts and other soluble chemical elements indicate relative amounts of movement in the profile over long periods of time, to the order of several million years. Iron, both in total concentration and in the form of various extracts, indicates it can be used as a geochronometer to assess the buildup of goethite plus hematite over time in the paleosols. Trends for ferrihydrite, a partially soluble Fe-hydroxide, shows limited profile translocation that might be related to the movement of salt. Six of the eight selected subsamples from paleosol horizons in three soil profiles contained nil concentrations of bacteria and fungi. However, two horizons at depths of between three to eight centimeters yielded several colonies of the fungi Beauveria bassiana and Penicillium spp., indicating some input of organic carbon. Beauveria bassiana is often reported in association with insects and is used commercially for the biological control of some insect pests. Penicillium species are commonly isolated from Arctic, temperate and tropical soils and are known to utilize a wide variety of organic

  9. Contribution of Soil Fauna to Foliar Litter-Mass Loss in Winter in an Ecotone between Dry Valley and Montane Forest in the Upper Reaches of the Minjiang River.

    Directory of Open Access Journals (Sweden)

    Yan Peng

    Full Text Available Litter decomposition during winter can provide essential nutrients for plant growth in the subsequent growing season, which plays important role in preventing the expansion of dry areas and maintaining the stability of ecotone ecosystems. However, limited information is currently available on the contributions of soil fauna to litter decomposition during winter in such ecosystems. Therefore, a field experiment that included litterbags with two different mesh sizes (0.04 mm and 3 mm was conducted to investigate the contribution of soil fauna to the loss of foliar litter mass in winter from November 2013 to April 2014 along the upper reaches of the Minjiang River. Two litter types of the dominant species were selected in each ecosystem: cypress (Cupressus chengiana and oak (Quercus baronii in ecotone; cypress (Cupressus chengiana and clovershrub (Campylotropis macrocarpa in dry valley; and fir (Abies faxoniana and birch (Betula albosinensis in montane forest. Over one winter incubation, foliar litter lost 6.0%-16.1%, 11.4%-26.0%, and 6.4%-8.5% of initial mass in the ecotone, dry valley and montane forest, respectively. Soil fauna showed obvious contributions to the loss of foliar litter mass in all of the ecosystems. The highest contribution (48.5%-56.8% was observed in the ecotone, and the lowest contribution (0.4%-25.8% was observed in the montane forest. Compared with other winter periods, thawing period exhibited higher soil fauna contributions to litter mass loss in ecotone and dry valley, but both thawing period and freezing period displayed higher soil fauna contributions in montane forest. Statistical analysis demonstrated that the contribution of soil fauna was significantly correlated with temperature and soil moisture during the winter-long incubation. These results suggest that temperature might be the primary control factor in foliar litter decomposition, but more active soil fauna in the ecotone could contribute more in litter

  10. Antarctic research today

    International Nuclear Information System (INIS)

    With the appetite for living and dead natural resources, the political and economical interest concerning the Antarctic increases throughout the world. There are three interrelated main subjects accounting for the international interest: The shelf tectonic puzzle of the original continent of Gondwana, where the Antarctic is situated in the centre, between Australia, South Africa and South America, and the hopes concerning the existence of mineral resources under the ice of the Antarctic are based thereon. The Antarctic forms the biggest unified living space of the world. (orig.)

  11. 77 FR 23766 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2012-04-20

    ... amended by the Antarctic Science, Tourism and Conservation Act of 1996, has developed regulations for the... Protected Areas (ASPA's), The applicant plans to enter ASPA 116-New College Valley, Cape Bird; ASPA 121-Cape... imagery will used for further scientific analysis. Location ASPA 116-New College Valley, Cape Bird;...

  12. 77 FR 41809 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2012-07-16

    .... 95-541), as amended by the Antarctic Science, Tourism and Conservation Act of 1996, has developed... Island, ASPA 116--New College Valley, Caughley Beach, Cape Bird, Ross Island, ASPA 121--Cape Royds, ASPA...--New College Valley, Caughley Beach, Cape Bird, Ross Island, ASPA 121--Cape Royds, ASPA...

  13. Searching for eukaryotic life preserved in Antarctic permafrost

    Science.gov (United States)

    Onofri, Silvano; Zucconi, Laura; Selbmann, Laura; Ripa, Caterina; Frisvad, Jens Christian; Guglielmin, Mauro; Turchetti, Benedetta; Buzzini, Pietro

    Permafrost is defined as a soil remaining at 0 C or below throughout two or more consecutive years. Mainly present in polar areas, it occurs in all ice-free areas of Continental Antarc-tica. With the evidences of the possible presence of water ice below the surface of Mars and Moon, permafrost is now considered a possible reservoir of prokaryotic and eukaryotic spores outside the Earth. Cultivable fungi and yeasts have been isolated from Antarctic permafrost collected at different depths (233, 316 and 335 cm) in the McMurdo Dry Valleys, the largest ice-free area in Antarctica, and identified with cultural, physiological and molecular methods. Filamentous fungi belonged to the genera Penicillium, Eurotium, Cladosporium, Alternaria, Engyodonthium, Cordiceps, Rhizopus, Aureobasidium, whereas yeasts belonged to the genera Cryptococcus and Sporidiobolus. Penicillia were the most represented, and the most frequently recorded species were Penicillium palitans and P. chrysogenum. Most of the species found have been already recorded in Antarctic ecosystems as well as in other cold habitats (Onofri et al., 2007); for Eurotium amstelodami and Cryptococcus stepposus these are the first isolations in Antarctica. All the filamentous fungal isolates can be defined as mesophilic having optimal growth temperatures at 20-25 C and poor growth at 0 C after prolonged incubation. All the yeast isolates grew within a wide range of temperature (from 4 to 25 C). The molecular anal-yses based on the ITS rDNA sequences, for filamentous fungi, and on D1/D2 domain of LSU rRNA gene and ITS sequences for yeasts, revealed that these genotypes do not deviate from the global gene pool of microorganisms commonly spreading worldwide at present. Annual mean permafrost temperature (MAPT) in the sampling area was -18.8 C in 2008, with daily fluctuations lower than 1 C/day at 1 m of depth, but less 0.5 C/year at the depth of 17 m (Guglielmin pers. com.), and maximum thaw depth not exceeding 1 m

  14. Microbial biomass and basal respiration in Sub-Antarctic and Antarctic soils in the areas of some Russian polar stations

    Directory of Open Access Journals (Sweden)

    E. Abakumov

    2014-03-01

    Full Text Available Antarctica is the unique place for pedological investigations. Soils of Antarctica have been studied intensively during the last century. Antarctic logistic provides the possibility to scientists access the terrestrial landscapes mainly in the places of polar stations. That is why the main and most detailed pedological investigations were conducted in Mc Murdo Valleys, Transantarctic Mountains, South Shetland Islands, Larsemann hills and Schirmacher Oasis. Investigations were conducted during the 53rd and 55th Russian Antarctic expeditions on the base of soil pits and samples collected in Sub-Antarctic and Antarctic regions. Soils of diverse Antarctic landscapes were studied with aim to assess the microbial biomass level, basal respiration rates and metabolic activity of microbial communities. The investigation conducted shows that soils of Antarctic are quite different in profile organization and carbon content. In general, Sub-Antarctic soils are characterized by more developed humus (sod organo-mineral horizons as well as the upper organic layer. The most developed organic layers were revealed in peat soils of King-George Island, where its thickness reach even 80 cm. These soils as well as soils under guano are characterized by the highest amount of total organic carbon (TOC 7.22–33.70%. Coastal and continental soils of Antarctic are presented by less developed Leptosols, Gleysols, Regolith and rare Ornhitosol with TOC levels about 0.37–4.67%. The metabolic ratios and basal respiration were higher in Sub-Antarctic soils than in Antarctic ones which can be interpreted as result of higher amounts of fresh organic remnants in organic and organo-mineral horizons. Also the soils of King-George island have higher portion of microbial biomass (max 1.54 mg g−1 than coastal (max 0.26 mg g−1 and continental (max 0.22 mg g−1 Antarctic soils. Sub-Antarctic soils mainly differ from Antarctic ones in increased organic layers thickness and total

  15. Separate origins of ice-binding proteins in antarctic chlamydomonas species.

    Directory of Open Access Journals (Sweden)

    James A Raymond

    Full Text Available The green alga Chlamydomonas raudensis is an important primary producer in a number of ice-covered lakes and ponds in Antarctica. A C. raudensis isolate (UWO241 from Lake Bonney in the McMurdo Dry Valleys, like many other Antarctic algae, was found to secrete ice-binding proteins (IBPs, which appear to be essential for survival in icy environments. The IBPs of several Antarctic algae (diatoms, a prymesiophyte, and a prasinophyte are similar to each other (here designated as type I IBPs and have been proposed to have bacterial origins. Other IBPs (type II IBPs that bear no resemblance to type I IBPs, have been found in the Antarctic Chlamydomonas sp. CCMP681, a putative snow alga, raising the possibility that chlamydomonad IBPs developed separately from the IBPs of other algae. To test this idea, we obtained the IBP sequences of C. raudensis UWO241 by sequencing the transcriptome. A large number of transcripts revealed no sequences resembling type II IBPs. Instead, many isoforms resembling type I IBPs were found, and these most closely matched a hypothetical protein from the bacterium Stigmatella aurantiaca. The sequences were confirmed to encode IBPs by the activity of a recombinant protein and by the matching of predicted and observed isoelectric points and molecular weights. Furthermore, a mesophilic sister species, C. raudensis SAG49.72, showed no ice-binding activity or PCR products from UWO241 IBP primers. These results confirm that algal IBPs are required for survival in icy habitats and demonstrate that they have diverse origins that are unrelated to the taxonomic positions of the algae. Last, we show that the C. raudensis UWO241 IBPs can change the structure of ice in a way that could increase the survivability of cells trapped in the ice.

  16. Separate origins of ice-binding proteins in antarctic chlamydomonas species.

    Science.gov (United States)

    Raymond, James A; Morgan-Kiss, Rachael

    2013-01-01

    The green alga Chlamydomonas raudensis is an important primary producer in a number of ice-covered lakes and ponds in Antarctica. A C. raudensis isolate (UWO241) from Lake Bonney in the McMurdo Dry Valleys, like many other Antarctic algae, was found to secrete ice-binding proteins (IBPs), which appear to be essential for survival in icy environments. The IBPs of several Antarctic algae (diatoms, a prymesiophyte, and a prasinophyte) are similar to each other (here designated as type I IBPs) and have been proposed to have bacterial origins. Other IBPs (type II IBPs) that bear no resemblance to type I IBPs, have been found in the Antarctic Chlamydomonas sp. CCMP681, a putative snow alga, raising the possibility that chlamydomonad IBPs developed separately from the IBPs of other algae. To test this idea, we obtained the IBP sequences of C. raudensis UWO241 by sequencing the transcriptome. A large number of transcripts revealed no sequences resembling type II IBPs. Instead, many isoforms resembling type I IBPs were found, and these most closely matched a hypothetical protein from the bacterium Stigmatella aurantiaca. The sequences were confirmed to encode IBPs by the activity of a recombinant protein and by the matching of predicted and observed isoelectric points and molecular weights. Furthermore, a mesophilic sister species, C. raudensis SAG49.72, showed no ice-binding activity or PCR products from UWO241 IBP primers. These results confirm that algal IBPs are required for survival in icy habitats and demonstrate that they have diverse origins that are unrelated to the taxonomic positions of the algae. Last, we show that the C. raudensis UWO241 IBPs can change the structure of ice in a way that could increase the survivability of cells trapped in the ice. PMID:23536869

  17. Potential extinction of Antarctic endemic fungal species as a consequence of global warming

    Energy Technology Data Exchange (ETDEWEB)

    Selbmann, Laura, E-mail: selbmann@unitus.it [Department of Ecological and Biological Sciences (DEB), Universita degli Studi della Tuscia, Largo dell' Universita, 01100 Viterbo (Italy); Isola, Daniela; Fenice, Massimiliano; Zucconi, Laura [Department of Ecological and Biological Sciences (DEB), Universita degli Studi della Tuscia, Largo dell' Universita, 01100 Viterbo (Italy); Sterflinger, Katja [Department of Biotechnology, Austrian Center of Biological Resources and Applied Mycology (ACBR), University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Wien (Austria); Onofri, Silvano [Department of Ecological and Biological Sciences (DEB), Universita degli Studi della Tuscia, Largo dell' Universita, 01100 Viterbo (Italy)

    2012-11-01

    Cryomyces spp. are fungi adapted to the harsh conditions of the McMurdo Dry Valleys in the Antarctic. The structure of their cell wall is one of the main factors for their uncommon ability to survive external stressors. The cells are, in fact, embedded in a thick and strongly melanised cell wall encrusted with black rigid plaques giving a supplementary protection and making them practically impregnable and refractory even to commercial enzymes including chitinases and glucanases. The Antarctic fungus Lecanicillium muscarium CCFEE 5003, able to produce an arsenal of lytic enzymes, including chitinases and glucanases, is known for its ability to degrade the cell walls of different food spoiling and opportunistic fungi as well as plant pathogenic Oomycota. Active cells of Cryomyces spp. were cultivated in dual culture with the mycoparasitic fungus both in liquid and solid media. Light microscope observations revealed that the cell walls of Cryomyces were heavily decayed. This resulted in the release of protoplasts. Hyphae penetration was evident with both scanning and transmission electron microscope observations. Due to its ecological amplitude (i.e. temperature growth range 0-28 Degree-Sign C), the parasitic fungus could easily expand its area of distribution as a consequence of global warming by invading new areas towards the interior of the continent. The establishment of interactions with organisms living at present in border ecosystems may lead to extinction of extremely specialized and poorly competitive entities. -- Highlights: Black-Right-Pointing-Pointer We studied interactions among Antarctic fungi to evaluate the effects of global warming. Black-Right-Pointing-Pointer Cryomyces spp. was parasitized and killed by Lecanicillum muscarium in co-cultures. Black-Right-Pointing-Pointer L. muscarium lythic activities may have intriguing and new applications. Black-Right-Pointing-Pointer L. muscarium may expand its area of distribution as a consequence of global

  18. Potential extinction of Antarctic endemic fungal species as a consequence of global warming

    International Nuclear Information System (INIS)

    Cryomyces spp. are fungi adapted to the harsh conditions of the McMurdo Dry Valleys in the Antarctic. The structure of their cell wall is one of the main factors for their uncommon ability to survive external stressors. The cells are, in fact, embedded in a thick and strongly melanised cell wall encrusted with black rigid plaques giving a supplementary protection and making them practically impregnable and refractory even to commercial enzymes including chitinases and glucanases. The Antarctic fungus Lecanicillium muscarium CCFEE 5003, able to produce an arsenal of lytic enzymes, including chitinases and glucanases, is known for its ability to degrade the cell walls of different food spoiling and opportunistic fungi as well as plant pathogenic Oomycota. Active cells of Cryomyces spp. were cultivated in dual culture with the mycoparasitic fungus both in liquid and solid media. Light microscope observations revealed that the cell walls of Cryomyces were heavily decayed. This resulted in the release of protoplasts. Hyphae penetration was evident with both scanning and transmission electron microscope observations. Due to its ecological amplitude (i.e. temperature growth range 0–28 °C), the parasitic fungus could easily expand its area of distribution as a consequence of global warming by invading new areas towards the interior of the continent. The establishment of interactions with organisms living at present in border ecosystems may lead to extinction of extremely specialized and poorly competitive entities. -- Highlights: ► We studied interactions among Antarctic fungi to evaluate the effects of global warming. ► Cryomyces spp. was parasitized and killed by Lecanicillum muscarium in co-cultures. ► L. muscarium lythic activities may have intriguing and new applications. ► L. muscarium may expand its area of distribution as a consequence of global warming. ► Extinction of threatened species previously living in confined niches may occur.

  19. Micro-hole and multigrain quartz luminescence dating of Paleodeltas at Lake Fryxell, McMurdo Dry Valleys (Antarctica), and relevance for lake history

    DEFF Research Database (Denmark)

    Berger, G.W.; Doran, P.T.; Thomsen, Kristina Jørkov

    2013-01-01

    Valley, and the boundaries of the proposed LGM ice-damned Glacial Lake Washburn. The timing of these high lake levels has depended on 14C chronologies of algal layers within relict lacustrine deltas. To provide additional geochronometric data for the post-LGM lake-level history, we applied photon......Relict (perched) lacustrine deltas around the perennially ice-covered lakes in the Taylor Valley, Antarctica, imply that these lakes were up to 40 times larger in area than at present since the last glacial maximum (LGM). These deltas have been used to constrain ice-margin positions in Taylor......-stimulated-luminescence (PSL) sediment dating to polymineral fine silt and sand-size quartz from 7 perched-delta and 3 active delta sites of different elevations along 3 major meltwater streams entering Lake Fryxell. Our PSL dating of 4 quartz-sand samples from core tops in the seasonal ice-free moat of Lake Fryxell...

  20. Closed basin brine evolution and the influence of Ca-Cl inflow waters : Death Valley and Bristol Dry Lake California, Qaidam Basin, China, and Salar de Atacama, Chile

    OpenAIRE

    Lowenstein, T. K.; Risacher, François

    2009-01-01

    Diagenetic-hydrothermal brines, here called "hydrothermal Ca-Cl brines," have compositions that reflect interactions between groundwaters and rocks or sediments at elevated temperatures. Hydrothermal Ca-Cl brines reach the surface by convection-driven or topographically driven circulation, and discharge as springs or seeps along fault zones to become important inflow waters in many tectonically active closed basins. Case studies from (1) Qaidam Basin, China, (2) Death Valley, California, (3) ...

  1. Sustaining dry surfaces under water

    DEFF Research Database (Denmark)

    Jones, Paul R.; Hao, Xiuqing; Cruz-Chu, Eduardo R.;

    2015-01-01

    Rough surfaces immersed under water remain practically dry if the liquid-solid contact is on roughness peaks, while the roughness valleys are filled with gas. Mechanisms that prevent water from invading the valleys are well studied. However, to remain practically dry under water, additional...... mechanisms need consideration. This is because trapped gas (e.g. air) in the roughness valleys can dissolve into the water pool, leading to invasion. Additionally, water vapor can also occupy the roughness valleys of immersed surfaces. If water vapor condenses, that too leads to invasion. These effects have...... not been investigated, and are critically important to maintain surfaces dry under water.In this work, we identify the critical roughness scale, below which it is possible to sustain the vapor phase of water and/or trapped gases in roughness valleys – thus keeping the immersed surface dry. Theoretical...

  2. 76 FR 58049 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2011-09-19

    .... 95-541), as amended by the Antarctic Science, Tourism and Conservation Act of 1996, has developed... Island (ASPA 105), New College Valley, Cape Bird (ASPA 116), Cape Royds (ASPA 121), Arrival Heights (ASPA... College Valley, Cape Bird, ASPA 121-Cape Royds, ASPA 122-Arrival Heights, ASPA 124-Cape Crozier, ASPA...

  3. Sugars in Antarctic aerosol

    Science.gov (United States)

    Barbaro, Elena; Kirchgeorg, Torben; Zangrando, Roberta; Vecchiato, Marco; Piazza, Rossano; Barbante, Carlo; Gambaro, Andrea

    2015-10-01

    The processes and transformations occurring in the Antarctic aerosol during atmospheric transport were described using selected sugars as source tracers. Monosaccharides (arabinose, fructose, galactose, glucose, mannose, ribose, xylose), disaccharides (sucrose, lactose, maltose, lactulose), alcohol-sugars (erythritol, mannitol, ribitol, sorbitol, xylitol, maltitol, galactitol) and anhydrosugars (levoglucosan, mannosan and galactosan) were measured in the Antarctic aerosol collected during four different sampling campaigns. For quantification, a sensitive high-pressure anion exchange chromatography was coupled with a single quadrupole mass spectrometer. The method was validated, showing good accuracy and low method quantification limits. This study describes the first determination of sugars in the Antarctic aerosol. The total mean concentration of sugars in the aerosol collected at the "Mario Zucchelli" coastal station was 140 pg m-3; as for the aerosol collected over the Antarctic plateau during two consecutive sampling campaigns, the concentration amounted to 440 and 438 pg m-3. The study of particle-size distribution allowed us to identify the natural emission from spores or from sea-spray as the main sources of sugars in the coastal area. The enrichment of sugars in the fine fraction of the aerosol collected on the Antarctic plateau is due to the degradation of particles during long-range atmospheric transport. The composition of sugars in the coarse fraction was also investigated in the aerosol collected during the oceanographic cruise.

  4. Antarctic ozone depletion

    International Nuclear Information System (INIS)

    Antarctic ozone depletion is most severe during the southern hemisphere spring, when the local reduction in the column amount may be as much as 50 percent. The extent to which this ozone poor air contributes to the observed global ozone loss is a matter of debate, but there is some evidence that fragments of the 'ozone hole' can reach lower latitudes following its breakup in summer. Satellite data show the seasonal evolution of the ozone hole. A new dimension has been added to Antarctic ozone depletion with the advent of large volcanic eruptions such as that from Mount Pinatubo in 1991. (author). 5 refs., 1 fig

  5. 岷江上游干旱河谷旱地土壤斥水性特征初步研究%Preliminary Study on the Characteristics of Soil Repellency in the Dry Valley of Minjiang River

    Institute of Scientific and Technical Information of China (English)

    秦纪洪; 赵利坤; 孙辉; 李沙

    2012-01-01

    土壤斥水性是土壤颗粒不易被水滴浸润的现象,对土壤水分特征曲线、土壤溶质运移、土壤优先流、土壤导水率以及地表径流和土壤侵蚀等具有重要影响。研究结果表明,3月份岷江上游干旱河谷0-5cm土层具斥水性的土壤在空间上的分布概率约为34%,其中强度斥水性土壤分布比例为5%;在时间分布上,土壤斥水性主要表现在7月,轻度以下斥水性概率为91%,强度以上斥水性概率为58%;从各粒级土壤斥水性的研究结果来看,斥水性与土壤粒级呈显著负相关,粒级越小,土壤斥水性越高。因此,岷江上游干旱河谷旱地土壤斥水性具有明显的时空分布差异,并且粒级越小土壤斥水性越强,7月份土壤表层的土壤斥水性强度与分布比例高。这可能是导致干旱河谷严重水土流失、土壤砂砾化的一个重要原因。%Soil water repellency is a widespread hydrologic phenomenon in different soils all over the world,and its implications encompass hysteresis of the water retention curve,unstable wetting fronts with fingered flow,reduced infiltration capacity as compared to wettable soils,and accelerated hillslope runoff and erosion.The results show that probability of 0-5 cm layer of soil with slight and strong repellency is about 34% in total,of which soil with strong water repellency is 5% in the dry valley of Minjiang River in March.In July,the probability of soil with slight and strong repellency is 91%,in which 58% is strong water repellent soil.The results also show that soil water repellency is significantly negatively related to the ratio of soil particle size.It can be concluded that there are apparently temporal and spatial variability for soil water repellency and water repellent soil distribution in the dry valley of Minjiang River.A higher ratio of strong soil water repellency exhibits in July of monsoon in topsoil,and in soil with higher proportion of fine fraction,which may be one of

  6. Dynamics of Bactrocera dorsalis in Jujube Orchards in Dry Hot Valley of Yuanmou%桔小实蝇在干热河谷区元谋枣园年发生动态研究

    Institute of Scientific and Technical Information of China (English)

    杨子祥; 沙毓沧; 王玖瑞; 刘海刚; 张德; 马开华; 杨建花; 段曰汤

    2013-01-01

    Bactrocera dors alls is one of the important insect pests harm Ziziphus mauritiana Lam. cv. Liuxiang and Ziziphus jujube, cv Jinsixiaozao in the dry hot valley. The text conduct a comprehensive analysis on the annual dynamics survey, climatic factors, food resources and host plants of Bactrocera dorsalis adult in the typical dry-hot valley of Yuanmou. The results show that the Bactrocera dorsalis in Ziziphus mauritiana Lam. cv. Liuxiang trap significantly higher than Ziziphus jujube, cv Jinsixiaozao; Bactrocera dorsalis adults in Ziziphus mauritiana Lam. cv. Liuxiang and Ziziphus jujube, cv Jinsixiaozao have one (August), two (February and August) peak, the peak period is basically consistent with fruit maturity; the monthly mean temperature, monthly rainfall and food source host plants are the main factors of population fluctuations. To master the changes in the population dynamics of Bactrocera dorsalis by two kinds of Zaoyuan monitoring, can timely provide a theoretical basis for Bactrocera dorsalis control period.%桔小实蝇[Bactrocera dorsalis (Hendel)]是危害干热河谷区台湾青枣(Ziziphus mauritiana Lam.cv.Liuxiang)和金丝小枣(Ziziphus Jujube.cv Jinsi-xiaozao)的重要害虫之一.对典型干热河谷气候区云南元谋台湾青枣和金丝小枣园桔小实蝇成虫的年发生动态进行调查,并就气候因子及食源寄主植物进行综合分析.结果表明:台湾青枣园桔小实蝇诱捕量明显高于金丝小枣园;桔小实蝇成虫在金丝小枣、台湾青枣上分别拥有1个(8月)、2个(2、8月)发生高峰期,高峰期与果实成熟期基本吻合;月均温、月降雨量和食源寄主植物是种群变动的主要因子.通过两种枣园桔小实蝇的监测,掌握种群动态的变化,可为适时制定桔小实蝇防治时期提供理论依据.

  7. Species composition and diversity characteristics of Quercus franchetii communities in dry-hot valley of Jinsha River%金沙江干热河谷锥连栎群落物种组成与多样性特征

    Institute of Scientific and Technical Information of China (English)

    刘方炎; 王小庆; 李昆; 孙永玉; 张志翔; 张春华

    2012-01-01

    金沙江干热河谷元谋段残存的锥连栎群落中植物种类组成较为简单,共发现68种植物,隶属于35科60属,其中,禾本科、蝶形花科、菊科、唇形科等科植物占有较大优势;从植物生活型和功能型来看,群落内以草本植物和多年生植物数量居多,分别占所有植物种类的58.8%和63.2%.不同类型群落中,除了扭黄茅始终为各群落中最为重要的优势种之外,同一草本植物在不同群落中的作用和地位存在较大差异;群落物种多样性及相似性程度较为低下,其Shannon-Weiner指数在1.7~2.6之间,且与群落受干扰程度存在较大关联.%Species composition and diversity characteristics of different Quercus franchetii communities in dry-hot valley of Jinsha River were studied based on the plots data. The results showed that there was a simple plant species composition in remained Q. franchetii communities in Jinsha River dry-hot valley of YuanMou section. In communities,68 plant species were found,which belong to 35 families 60 genera,and Poaceae,Papilionaceae, Asteraceae,and Lamiaceae plants had a large advantage; in the plant life form and functional type,the majority of the plants within communities were herbs and perennials,which occupied respectively 58. 8% and 63. 2%. In Q. franchetii communities , excepted that Heteropogon contortus was eventually the most important dominant species, the same herb in different communities were quite different in the role and status. Simultaneously,Q. franchetii communities had lower species diversity and similarity,and Shannon-Weiner index was between 1. 7 and 2. 6,which was correlated with the degree of disturbance of communities.

  8. Damage Escape and Repair in Dried Chroococcidiopsis spp. from Hot and Cold Deserts Exposed to Simulated Space and Martian Conditions

    Science.gov (United States)

    Billi, Daniela; Viaggiu, Emanuela; Cockell, Charles S.; Rabbow, Elke; Horneck, Gerda; Onofri, Silvano

    2011-01-01

    The cyanobacterium Chroococcidiopsis, overlain by 3mm of Antarctic sandstone, was exposed as dried multilayers to simulated space and martian conditions. Ground-based experiments were conducted in the context of Lichens and Fungi Experiments (EXPOSE-E mission, European Space Agency), which were performed to evaluate, after 1.5 years on the International Space Station, the survival of cyanobacteria (Chroococcidiopsis), lichens, and fungi colonized on Antarctic rock. The survival potential and the role played by protection and repair mechanisms in the response of dried Chroococcidiopsis cells to ground-based experiments were both investigated. Different methods were employed, including evaluation of the colony-forming ability, single-cell analysis of subcellular integrities based on membrane integrity molecular and redox probes, evaluation of the photosynthetic pigment autofluorescence, and assessment of the genomic DNA integrity with a PCR-based assay. Desiccation survivors of strain CCMEE 123 (coastal desert, Chile) were better suited than CCMEE 134 (Beacon Valley, Antarctica) to withstand cellular damage imposed by simulated space and martian conditions. Exposed dried cells of strain CCMEE 123 formed colonies, maintained subcellular integrities, and, depending on the exposure conditions, also escaped DNA damage or repaired the induced damage upon rewetting.

  9. Modelling the Antarctic Ice Sheet

    DEFF Research Database (Denmark)

    Pedersen, Jens Olaf Pepke; Holm, A.

    2015-01-01

    Science) Antarctic Ice Sheet (DAIS) model (Shaffer 2014) is forced by reconstructed time series of Antarctic temperature, global sea level and ocean subsurface temperature over the last two glacial cycles. In this talk a modelling work of the Antarctic ice sheet over most of the Cenozoic era using the......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 to...... DAIS model will be presented. G. Shaffer (2014) Formulation, calibration and validation of the DAIS model (version 1), a simple Antarctic ice sheet model sensitive to variations of sea level and ocean subsurface temperature, Geosci. Model Dev., 7, 1803‐1818...

  10. Antarctic Tourism and Maritime Heritage

    OpenAIRE

    Basberg, Bjørn L.

    2010-01-01

    Maritime activities in the Antarctic region date back to the eighteenth century. They evolved from exploration and discoveries to commercial enterprises, especially sealing, whaling and fishing. Antarctic tourism is a much more recent phenomenon, developing mainly from the 1950s and 1960s. Today over 40,000 tourists visit the Antarctic annually, most of them on cruise ships. This essay reviews the historical development of this tourism. The focus is on how maritime heritage has been treated a...

  11. Antarctic science preserve polluted

    Science.gov (United States)

    Simarski, Lynn Teo

    Geophysicists are alarmed at the electromagnetic pollution of a research site in the Antarctic specifically set aside to study the ionosphere and magnetosphere. A private New Zealand communications company called Telecom recently constructed a satellite ground station within the boundaries of this Site of Special Scientific Interest (SSSI), protected since the mid-1970s. The placement of a commercial facility within this site sets an ominous precedent not only for the sanctity of other SSSIs, but also for Specially Protected Areas—preserves not even open to scientific research, such as certain penguin rookeries.The roughly rectangular, one-by-one-half mile site, located at Arrival Heights not far from McMurdo Station, is one of a number of areas protected under the Antarctic treaty for designated scientific activities. Many sites are set aside for geological or biological research, but this is the only one specifically for physical science.

  12. Effect of Land Use on Soil Enzyme Activity in Dry-Hot Valley%不同土地利用方式对干热河谷地区土壤酶活性的影响

    Institute of Scientific and Technical Information of China (English)

    薛萐; 李占斌; 拳鹏; 郑郁

    2011-01-01

    [Objective] The study of soil enzyme activity on land use is of importance for exploration of the soil quality evolution and its evaluation during the revegetation in Jinsha river dry-hot valley region. [Method] Seven kinds of land use types with the same altitude at valleys in downstream of Jinsha river in Ningnan county, Sichuan was chosen as subject, aiming at reveal the changes in soil enzyme activity under wet/dry alternate conditions through experimental and statistical analysis. [Result] The results showed that different land use types significantly influenced the enzyme activity. Soil urease, saccharase, phosphatase, cellulose behaved the same change. Compared to other land use, a higher enzyme was found in Camptotheca acuminata, followed by grassland and Albizzia julibrissin, the lowest in Zanthoxylum bungeanum, Zea mays, Saccharum sinense and Mortis alba. No significant change was observed in catalase activity and the lower value was found in Zea mays, Morus alba, Saccharum sinense than other land use. Different changes were observed in polyphenol oxidase from other enzymes, and the Morus alba and Albizzia julibrissin corresponded the highest value. With a exception of polyphenol oxdiase, enzymes with the same land use at wet season were higher than that in dry season. Correlation analysis showed a significant relation among saccharase, urease, phosphatase, and catalase, also related with soil fertility indicators, therefore soil enzyme could be useful for reflecting soil fertility. Soil enzyme index (SEI) can objectively and fully evaluate the change in soil enzyme, the SEI changed with an order of Camptotheca acuminata > Albizzia julibrissin >grassland> Zea mays >Zanthoxylum bungeanum >Saccharum sinense > Morus alba, and the SEI in wet season was higher than dry season. [Conclusion] The significant difference was observed in different land use types owing to special factors such as framing environment and species composition. In order to

  13. Resistance of Antarctic black fungi and cryptoendolithic communities to simulated space and Martian conditions

    OpenAIRE

    Onofri, S.; Barreca, D.; Selbmann, L.; D. Isola; E. Rabbow; Horneck, G.; de Vera, J.P.P.; Hatton, J.; Zucconi, L.

    2008-01-01

    Dried colonies of the Antarctic rock-inhabiting meristematic fungi Cryomyces antarcticus CCFEE 515, CCFEE 534 and C. minteri CCFEE 5187, as well as fragments of rocks colonized by the Antarctic cryptoendolithic community, were exposed to a set of ground-based experiment verification tests (EVTs) at the German Aerospace Center (DLR, Köln, Germany). These were carried out to test the tolerance of these organisms in view of their possible exposure to space conditions outside of the International...

  14. Mantle domain and segmentation at the Australian-Antarctic Ridge

    Science.gov (United States)

    Park, S. H.; Langmuir, C. H.; Lin, J.; Kim, S.; Hahm, D.; Michael, P. J.; Scott, S. R.; Sims, K. W. W.

    2014-12-01

    The Australian-Antarctic ridge (AAR) is the largest unexplored expanse of the global mid-ocean ridges. Using the Korean Icebreaker Araon, we carried out a multi-disciplinary study of two segments (KR1 and KR2) of intermediate spreading AAR in three expeditions from 2011 to 2013. KR1, a 300-km-long supersegment located in the center of AAR, has large transform faults at its two ends, only small 3rd and 4th order offsets between the transforms, and no overlapping spreading centers. Nonetheless there are large variations in axial morphology from axial high to rift valley, as well as large changes in chemical and Pb isotopic composition. The KR2 segment is located about 200 km northwest of KR1 and connected to it by the Balleny transform. KR2 is a 180 km-long 1st order segment bounded by two transforms and consists of a western segment with axial high and an eastern segment with rift valley. Along-axis geochemical variations indicate that the magma flux and ridge morphology of are influenced by changing mantle composition on a fine scale, and thus magma transport to the crust must occur at multiple locations along this single segment. Both the KR1 and KR2 segments are on the Pacific side of the Australian-Antarctic-Discordance, long considered as the boundary between Pacific and Indian mantle. However, isotopic and trace elements data of these segments differ from samples from the Pacific-Antarctic Ridge, so flow of Pacific mantle into Indian mantle bounded by the Australian-Antarctic-Discordance is no longer supported.

  15. Origin and Phylogeny of Microbes Living in Permanent Antarctic Lake Ice.

    Science.gov (United States)

    Gordon, D. A.; Priscu, J.; Giovannoni, S.

    2000-04-01

    A BSTRACTThe phylogenetic diversity of bacteria and cyanobacteria colonizing sediment particles in the permanent ice cover of an Antarctic lake was characterized by analyses of 16S rRNA genes amplified from environmental DNA. Samples of mineral particles were collected from a depth of 2.5 m in the 4-m-thick ice cover of Lake Bonney, McMurdo Dry Valleys, Antarctica. A rRNA gene clone library of 198 clones was made and characterized by sequencing and oligonucleotide probe hybridization. The library was dominated by representatives of the cyanobacteria, proteobacteria, and Planctomycetales, but also contained diverse clones representing many other microbial groups, including the Acidobacterium/Holophaga division, the Green Non-Sulfur division, and the Actinobacteria. Six oligonucleotide probes were made for the most abundant clades recovered in the library. To determine whether the ice microbial community might originate from wind dispersal of the algal mats found elsewhere in Taylor Valley, the probes were hybridized to 16S rDNAs amplified from three samples of terrestrial cyanobacterial mats collected at nearby sites, as well as to bacterial 16S rDNAs from the lake ice community. The results demonstrate the presence of a diverse microbial community dominated by cyanobacteria in the lake ice, and also show that the dominant members of the lake ice microbial community are found in terrestrial mats elsewhere in the area. The lake ice microbial community appears to be dominated by organisms that are not uniquely adapted to the lake ice ecosystem, but instead are species that originate elsewhere in the surrounding region and opportunistically colonize the unusual habitat provided by the sediments suspended in lake ice. PMID:12035096

  16. Biodiversity and biogeography of Antarctic and sub-Antarctic mollusca

    Science.gov (United States)

    Linse, Katrin; Griffiths, Huw J.; Barnes, David K. A.; Clarke, Andrew

    2006-04-01

    For many decades molluscan data have been critical to the establishment of the concept of a global-scale increase in species richness from the poles to the equator. Low polar diversity is key to this latitudinal cline in diversity. Here we investigate richness patterns in the two largest classes of molluscs at both local and regional scales throughout the Southern Ocean. We show that biodiversity is very patchy in the Southern Ocean (at the 1000-km scale) and test the validity of historical biogeographic sub-regions and provinces. We used multivariate analysis of biodiversity patterns at species, genus and family levels to define richness hotspots within the Southern Ocean and transition areas. This process identified the following distinct sub-regions in the Southern Ocean: Antarctic Peninsula, Weddell Sea, East Antarctic—Dronning Maud Land, East Antarctic—Enderby Land, East Antarctic—Wilkes Land, Ross Sea, and the independent Scotia arc and sub Antarctic islands. Patterns of endemism were very different between the bivalves and gastropods. On the basis of distributional ranges and radiation centres of evolutionarily successful families and genera we define three biogeographic provinces in the Southern Ocean: (1) the continental high Antarctic province excluding the Antarctic Peninsula, (2) the Scotia Sea province including the Antarctic Peninsula, and (3) the sub Antarctic province comprising the islands in the vicinity of the Antarctic Circumpolar Current.

  17. Ecuadorian antarctic act

    International Nuclear Information System (INIS)

    To develop research in this continent involves to take communion with earth where the cold pole of the planet is located, the stormiest sea of the world surround it and where the capricious continental and geographical distribution permits the pass of meteorological violent and continuous systems. The Ecuador, in execution of the acquired commitments like Full Member of the System of the Antarctic Treaty, carried out the VII Expedition to the White Continent with an extensive program of scientific investigation in the field of: Sciences of Life, Sciences of the Earth and Atmospheric Sciences, so much in the environment of the Pacific Southeast, the Drake Pass, Bransfield Strait and the nearby ecosystems antarctic to Point Fort William in the Greenwich Island, site where the Ecuadorian station Pedro Vicente Maldonado is located. The scientific articles, result of the fruitful work of national investigator is consigned in this fourth edition. This publication constitutes our contribution to the world in the knowledge, understanding and handling of the marvelous White Continent from the middle of our planet, Ecuador

  18. 77 FR 26048 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2012-05-02

    .... 95-541), as amended by the Antarctic Science, Tourism and Conservation Act of 1996, has developed..., Caughley Beach, Cape Bird; ASPA 117--Avian Island; ASPA 121--Cape Royds; ASPA 124--Cape Crozier; ASPA 125... Island; ASPA 116--New College Valley, Caughley Beach, Cape Bird; ASPA 117--Avian Island; ASPA 121--...

  19. 76 FR 61117 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2011-10-03

    .... 95-541), as amended by the Antarctic Science, Tourism and Conservation Act of 1996, has developed... Heights, Ross Island (ASPA 122), Backdoor Bay, Cape Royds (ASPA 157), and New College Valley, Cape Bird... Bird (ASPA 116). Dates November 11, 2011 to December 31, 2011. Nadene G. Kennedy, Permit...

  20. 75 FR 21045 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2010-04-22

    .... 95-541), as amended by the Antarctic Science, Tourism and Conservation Act of 1996, has developed... values to examine diets, and for mercury (Hg). All capture bird will be released. Location: ASPA 102..., ASPA 115-Lagotellerie Island, Marguerite Bay, ASPA 116-New College Valley, Caughley Beach, Cape...

  1. 元谋干热河谷区森林消长与生态环境变化研究%Studies on the Increase and Decrease of Forest Area and Eco- environmental Change in Yuanmou Dry-hot Valley

    Institute of Scientific and Technical Information of China (English)

    张建平; 王道杰; 杨忠; 李勇

    2001-01-01

    In Yuanmou dry-hot valley, the forest cover rate is respectively 12.8% in 1950(In the early 1950s, above 2 000 m of the altitude in Liangshan area, there distributed Pinus yunnanensis forest, the forest cover rate reached 60%~70%. Between 1 500~2 000 m,still distributed tract Pinus yunnanensis forest.), 6.3% in 1973 (Because of the serious destruction during the periods of the “Great Leap” and “Cultural Revolution”, the forest area reduced greatly), 5.2% in 1985 (After 1978,because of the need of economic development, the forest was felled again) and 5.8% in 1993 (After 1985, energetically plant trees, the forest cover rate increased slightly). The human socio-economic activity (felled trees and plant trees) is the main cause of increase and decrease of forest area. The increase and the decrease of the forest area is the key of the eco-environment changes to good or bad condition (The decrease of forest area caused eco-environment worse. The drought and flood are gradually serious and the land desertification developed). Against forest decrease and eco-environment deterioration some countermeasures have been proposed to recover forest vegetation and improve eco-environment, i.e, strengthen young trees management and tending, close hills to facilitate afforestation and change slope cultivated land to afforestation; formulate favourable policy; rationally dispose tree species; use water-saving technique in afforestation .%在元谋干热河谷区,森林覆盖率1950年为12.8%、1973年为6.3%、1985年降至5.2%、1993年升至5.8%。而人类的社会、经济活动,是导致森林面积消长的主要原因。森林面积增减,是生态环境向良性或恶性方向转变的关键所在,针对森林减少和生态环境恶化的原因提出了恢复森林植被改善生态环境的对策。

  2. DEWFALL AS A WATER SOURCE FREQUENTLY ACTIVATES THE ENDOLITHIC CYANOBACTERIAL COMMUNITIES IN THE GRANITES OF TAYLOR VALLEY, ANTARCTICA(1).

    Science.gov (United States)

    Büdel, Burkhard; Bendix, Jörg; Bicker, Fritz R; Allan Green, T G

    2008-12-01

    Endolithic photosynthetic microorganisms like cyanobacteria and algae are well known from savannas and deserts of the world, the high Arctic, and also Antarctic habitats like the Dry Valleys in the Ross Dependency. These endolithic microbial communities are thought to be at the limits of life with reported ages in the order of thousands of years. Here we report on an extensive chasmoendolithic cyanobacterial community inside granite rocks of Mt. Falconer in the lower Taylor Valley, Dry Valleys. On average, the cyanobacterial community was 4.49 ± 0.95 mm below the rock surface, where it formed a blue-green layer. The community was composed mainly of the cyanobacterium Chroococcidiopsis sp., with occasional Cyanothece cf. aeruginosa (Nägeli) Komárek and Nostoc sp. Mean biomass was 168 ± 44 g carbon · m(-2) , and the mean chl a content was 24.3 ± 34.2 mg · m(-2) . In situ chl fluorescence measurements-a relative measure of photosynthetic activity-showed that they were active over long periods each day and also showed activity the next day in the absence of any moisture. Radiocarbon dating gave a relatively young age (175-280 years) for the community. Calculations from microclimate data demonstrated that formation of dew or rime was possible and could frequently activate the cyanobacteria and may explain the younger age of microbial communities at Mt. Falconer compared to older and less active endolithic microorganisms reported earlier from Linnaeus Terrace, a higher altitude region that experiences colder, drier conditions. PMID:27039856

  3. Wonder Valley

    OpenAIRE

    Hillyard, William

    2013-01-01

    You might have passed through here, maybe. Thought you'd stick to the blue roads, hit the casinos of Vegas by the back way. As you blew through this nowhere corner of the Mojave Desert you might have noticed the rat-trap shacks rotting into the sparse hardscrabble of greasewood scrub. And you'd have thought, "What the hell is this place?" Wonder Valley. Out here, thousands of dilapidated cabins crumble into the desert, each one 12 by 20, an outhouse out back. They sit on a grid of five acre p...

  4. Fine-scale Spatial Pattern Typical Vegetation at the Dry Minjiang River Valley%岷江干旱河谷中心地段植被微尺度空间格局特征

    Institute of Scientific and Technical Information of China (English)

    王晶; 包维楷

    2011-01-01

    微尺度景观格局是景观生态学的一个研究热点.干旱河谷是横断山区一类特殊的生态系统类型,生态脆弱,生态退化潜在风险大.选择四川茂县两河口典型样地干旱河谷微尺度景观格局进行研究.研究表明,样地上分布的景观类型多样,斑块类型有19个,植被景观总斑块达3 383个,以基质分布为主,植被斑块状镶嵌其中,主要以中生性耐旱植物为主,植被覆盖度为42.25%.植被景观类型大部分为豆科类灌丛景观,整个景观由川甘亚菊、刺蓬、瓦松、茂汶韭、狗尾草、小角柱花、侧柏、臭椿、滇柏、卷柏、元宝枫、岷江柏景观斑块控制.植被景观分布特征为,帚菊斑块面积最大且分布均匀,小马鞍羊蹄甲斑块最大且聚集度最高,狗尾草斑块破碎化程度最大,蚊子草斑块多样性程度最大,小角柱花多样性程度最小且分布最散.通过空间自相关性分析,研究区植物分布呈现较高的正相关性和空间聚集性,在尺度2m×2m空间自相关值最大,未来干旱河谷区微尺度空间格局研究尺度在这个尺度较适宜.%The dry Minjiang river valley is a special kind of cross-sectional type of ecological system, with its ecological fragility, the potential risks of degradation. We analyzed land cover categories(20 m ×20 m of extent and 1 mm of resolution) and images of vegetation index in MAO county. This study showed that the landscape diversity in the experimental plots are significant with 19 patch types and total 3 383 patches of vegetation. The regional distribution was matrix-based, patchy mosaic of vegetation in which endogenous drought-tolerant plants predominated. The vegetation coverage is 42. 25%. Most of the vegetation in the landscape are shrub legumes, the vegetation types include Pertya phylicoides, Sophora viciifolia Hance ,Ajania potaninii, Herba Euphorbiae Milii, W. Stnophylla, Iudigofera lenticellata,Orostachys fimbriatus,Bauhiniafaberi var

  5. 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

  6. Towers for Antarctic Telescopes

    Science.gov (United States)

    Hammerschlag, R. H.; Bettonvil, F. C. M.; Jägers, A. P. L.; Nielsen, G.

    To take advantage of the exceptional seeing above the boundary layer on Antarctic sites, a high-resolution telescope must be mounted on a support tower. An open transparent tower of framework minimizes the upward temperature-disturbed airflow. A typical minimum height is 30m. The tower platform has to be extremely stable against wind-induced rotational motions, which have to be less than fractions of an arc second, unusually small from a mechanical engineering viewpoint. In a traditional structure, structural deflections result in angular deflections of the telescope platform, which introduce tip and tilt motions in the telescope. However, a structure that is designed to deflect with parallel motion relative to the horizontal plane will undergo solely translation deflections in the telescope platform and thus will not degrade the image. The use of a parallel motion structure has been effectively demonstrated in the design of the 15-m tower for the Dutch Open Telescope (DOT) on La Palma. Special framework geometries are developed, which make it possible to construct high towers in stories having platforms with extreme stability against wind-induced tilt. These geometric solutions lead to constructions, being no more massive than a normal steel framework carrying the same load. Consequently, these lightweight towers are well suited to difficult sites as on Antarctica. A geometry with 4 stories has been worked out.

  7. Evolution and ecology of antarctic sponges

    OpenAIRE

    Vargas Ramirez, Sergio

    2012-01-01

    Sponges are abundant and species-rich in Antarctic waters, and play important roles in the benthic ecosystems of the continent. The taxonomy of Antarctic sponges is, to some extent, well established, yet the phylogenetic relationships of this fauna remain unknown. Here, the first contributions to the knowledge of the evolution of Antarctic sponges are presented. A molecular phylogeny for the common Antarctic shelf glass sponge genus Rossella is provided. Based on nuclear and mitochondrial mar...

  8. Evolution and controlling factors of vertical hole in Yuanmou Dry-hot Valley%元谋干热河谷竖井的演化与控制因素

    Institute of Scientific and Technical Information of China (English)

    王磊; 邓青春; 张斌; 刘辉; 刘刚才; 罗明良; 舒成强

    2015-01-01

    The vertical hole is a special kind of piping landforms;it is the disastrous environmental problem that cannot be ignored under the background of large-scale soil erosion. The development of vertical hole indicates the lateral erosion of gully,so that it has a huge impact on shoulder line shape of gully. It is very important to study the evolution and formation of vertical holes for understanding the mechanics of lateral and backward erosion of gully. Based on the investigations of vertical holes at Shadi Village of Yuanmou Dry-hot Valley,they can be divided into germination period,expanding period,complete period,broken period and residual period. There are significant differences between plane shape and cross-sectional shape of vertical hole at different developmental stage. The ver-tical hole of complete period is the most representative stage,the changes of long axis,short axis and the depth of vertical holes are in the range between 0. 75~3. 29 m,1. 01~2. 84 m,1. 98~10. 26 m;the ratio of long axis and short axis is between 0 . 3~3 . 1 . The morphology and developmental process are mainly controlled by the factors of precipitation and surface runoff,structure,soil properties,terrain and vegetation etc. This paper not only contributes to the understanding of the formation and evolution of the vertical hole,but also provides scientific guidance for treatment of engineering geological hazard prevention and monitoring of gully erosion.%竖井是一种特殊的潜蚀地貌类型,是大规模土壤侵蚀背景下不容忽视的灾害性环境问题。竖井的发育是冲沟侧蚀后退的一种方式,对冲沟沿线形态影响巨大,研究其成因和演化过程对认识冲沟的侧蚀和后退机制具有很大的参考价值。基于对元谋干热河谷沙地村竖井群的实地考察和测量,将竖井的发育划分为萌芽期、扩张期、完整期、破碎期和残夷期5个阶段,不同发育阶段其平面形态与剖面形态具有显著的

  9. Antarctic Ozone Hole, 2000

    Science.gov (United States)

    2002-01-01

    Each spring the ozone layer over Antarctica nearly disappears, forming a 'hole' over the entire continent. The hole is created by the interaction of some man-made chemicals-freon, for example-with Antarctica's unique weather patterns and extremely cold temperatures. Ozone in the stratosphere absorbs ultraviolet radiation from the sun, thereby protecting living things. Since the ozone hole was discovered many of the chemicals that destroy ozone have been banned, but they will remain in the atmosphere for decades. In 2000, the ozone hole grew quicker than usual and exceptionally large. By the first week in September the hole was the largest ever-11.4 million square miles. The top image shows the average total column ozone values over Antarctica for September 2000. (Total column ozone is the amount of ozone from the ground to the top of the atmosphere. A relatively typical measurement of 300 Dobson Units is equivalent to a layer of ozone 0.12 inches thick on the Earth's surface. Levels below 220 Dobson Units are considered to be significant ozone depletion.) The record-breaking hole is likely the result of lower than average ozone levels during the Antarctic fall and winter, and exceptionally cold temperatures. In October, however (bottom image), the hole shrank dramatically, much more quickly than usual. By the end of October, the hole was only one-third of it's previous size. In a typical year, the ozone hole does not collapse until the end of November. NASA scientists were surprised by this early shrinking and speculate it is related to the region's weather. Global ozone levels are measured by the Total Ozone Mapping Spectrometer (TOMS). For more information about ozone, read the Earth Observatory's ozone fact sheet, view global ozone data and see these ozone images. Images by Greg Shirah, NASA GSFC Scientific Visualization Studio.

  10. Amino Acids as a Source of Organic Nitrogen in Antarctic Endolithic Microbial Communities

    Science.gov (United States)

    McDonald, G. D.; Sun, H. J.

    2002-12-01

    In the Antarctic Dry Valleys, cryptoendolithic microbial communities occur within porous sandstone rocks. Current understanding of the mechanisms of physiological adaptation of these communities to the harsh Antarctic environment is limited, because traditional methods of studying microbial physiology are very difficult to apply to organisms with extremely low levels of metabolic activity. In order to fully understand carbon and nitrogen cycling and nutrient uptake in cryptoendolithic communities, and the metabolic costs that the organisms incur in order to survive, it is necessary to employ molecular geochemical techniques such as amino acid analysis in addition to physiological methods. Low-molecular-weight biomolecules such as amino acids can be used as tracers of carbon and nitrogen uptake and loss by microbial communities living in solid-state matrices such as rock or sediment. We have measured the concentrations and D/L ratios for several amino acids as a function of depth in a large sandstone boulder. Concentrations of both free and bound amino acids decrease by more than two orders of magnitude from the surface to the visible base of the community (approximately 1.2 cm depth), while the D/L ratios of the amino acids increase from near zero to 0.2 or greater over the same depth interval. We interpret these data as an indication that one or more community members are selectively scavenging L-amino acids as the amino acids are transported through the rock by intermittently percolating meltwater. This is consistent with the known preference of lichens for amino acids as nitrogen sources rather than inorganic nitrogen under conditions of nutrient limitation. It is not yet clear whether there is also a contribution to amino acid uptake from heterotropic bacteria associated with the cryptoendolithic community. The increase in D/L ratios with depth observed in the rock is too great to be attributable solely to the natural occurrence of D-amino acids in bacteria

  11. Biomarkers and Microbial Fossils In Antarctic Rocks

    Science.gov (United States)

    Wierzchos, J.; Ascaso, C.

    Lithobiontic microbial communities living within Antarctic rocks are an example of survival in an extremely cold and dry environment. Any unfavourable change in ex- ternal conditions can result in the death and disappearance of microscopic organisms, and this may be followed by the appearance of trace biomarkers and microbial fossils. The extinction of these microorganisms in some zones of the Ross Desert, probably provoked by the hostile environment, might be considered a good terrestrial analogue of the first stage of the disappearance of possible life on early Mars. Granite samples from maritime Antarctica (Granite Harbour) and sandstone rocks from the continental Ross Desert were collected with the aim of searching for biomarkers and microbial fossils at the microscopic level of observation. To this end, a novel in situ applica- tion of scanning electron microscopy with backscattered electron imaging was com- bined with the simultaneous use of X-ray energy dispersive spectroscopy techniques. Our findings confirm the existence of inorganic biomarkers in the form of physico- chemically bioweathered minerals within the granitic rocks. The presence of Fe-rich diagenetic minerals, such as iron hydroxide nanocrystals and biogenic clays around chasmoendolithic hyphae and bacterial cells was also observed. Others biomarkers, including inorganic deposits such as calcium oxalates and silica accumulations, are clear signs of endolithic microorganism activity. The interior of the sandstone rocks (Ross Desert, Mt. Fleming) reveal the presence of microbial fossils of algae and other endolithic microorganisms. These microbial fossils, detected for the first time within Antarctic rocks, contain well preserved and morphologically distinguishable relics of ultrastructural cytoplasm elements, such as cell walls, chloroplast membranes, and oc- casionally, pyrenoids and traces of organic matter. These structures are similar to those observed in live cells also found in Antarctic

  12. The response of the East Antarctic ice-sheet to the evolving tectonic configuration of the Transantarctic Mountains

    Science.gov (United States)

    Kerr, Andrew; Huybrechts, Philippe

    1999-12-01

    ranges, such as the Dry Valleys and Victoria Land. The development of independent ice centres in the latter regions and the overriding of these ice centres by the main ice-sheet is very sensitive to the timing of surface uplift and the particular climate profile of the period. Conversely, the ice-surface profile across the central ranges is similar under widely different climates. The limitations of such a study stem from the necessarily schematic bedrock elevations input to the model and simplifications within the models. At present, insufficiently detailed modelling of the impact of troughs on ice-sheet dynamics means this paper is necessarily speculative. However, this work points to the importance of the outlet troughs on ice-sheet dynamics, rather than simply the rising surface elevations of the Transantarctic Mountains along the rift margin upwarp.

  13. Feeding repellence in Antarctic bryozoans

    Science.gov (United States)

    Figuerola, Blanca; Núñez-Pons, Laura; Moles, Juan; Avila, Conxita

    2013-11-01

    The Antarctic sea star Odontaster validus and the amphipod Cheirimedon femoratus are important predators in benthic communities. Some bryozoans are part of the diet of the asteroid and represent both potential host biosubstrata and prey for this omnivorous lysianassid amphipod. In response to such ecological pressure, bryozoans are expected to develop strategies to deter potential predators, ranging from physical to chemical mechanisms. However, the chemical ecology of Antarctic bryozoans has been scarcely studied. In this study we evaluated the presence of defenses against predation in selected species of Antarctic bryozoans. The sympatric omnivorous consumers O. validus and C. femoratus were selected to perform feeding assays with 16 ether extracts (EE) and 16 butanol extracts (BE) obtained from 16 samples that belonged to 13 different bryozoan species. Most species (9) were active (12 EE and 1 BE) in sea star bioassays. Only 1 BE displayed repellence, indicating that repellents against the sea star are mainly lipophilic. Repellence toward C. femoratus was found in all species in different extracts (10 EE and 12 BE), suggesting that defenses against the amphipod might be both lipophilic and hydrophilic. Interspecific and intraspecific variability of bioactivity was occasionally detected, suggesting possible environmental inductive responses, symbiotic associations, and/or genetic variability. Multivariate analysis revealed similarities among species in relation to bioactivities of EE and/or BE. These findings support the hypothesis that, while in some cases alternative chemical or physical mechanisms may also provide protection, repellent compounds play an important role in Antarctic bryozoans as defenses against predators.

  14. NNSS Soils Monitoring: Plutonium Valley (CAU 366)

    International Nuclear Information System (INIS)

    The U.S. Department of Energy (DOE) National Nuclear Security Administration (NNSA), Nevada Site Office (NSO), Environmental Restoration Soils Activity has authorized the Desert Research Institute (DRI) to conduct field assessments of potential sediment transport of contaminated soil from Corrective Action Unit (CAU) 366, Area 11 Plutonium Valley Dispersion Sites Contamination Area (CA) during precipitation runoff events.

  15. The carbon stable isotope biogeochemistry of streams, Taylor Valley, Antarctica

    International Nuclear Information System (INIS)

    Highlights: ► δ13C-DIC reported from McMurdo Dry Valleys, Antarctica, streams. ► Stream water δ13CPDB values range −9.4‰ to +5.1‰, largely inorganic in character. ► Atmospheric exchange is the dominant control on δ13C-DIC. - Abstract: The McMurdo Dry Valleys region of Antarctica is the largest ice-free region on the continent. This study reports the first C stable isotope measurements for dissolved inorganic C present in ephemeral streams in four dry valleys that flow for four to twelve weeks during the austral summer. One of these valleys, Taylor Valley, has been the focus of the McMurdo Dry Valleys Long-Term Ecological Research (MCM-LTER) program since 1993. Within Taylor Valley, numerous ephemeral streams deliver water to three perennially ice-covered, closed-basin lakes: Lake Fryxell, Lake Hoare, and Lake Bonney. The Onyx River in the Wright Valley, the longest river in Antarctica, flows for 40 km from the Wright Lower Glacier and Lake Brownworth at the foot of the glacier to Lake Vanda. Streamflow in the McMurdo Dry Valley streams is produced primarily from glacial melt, as there is no overland flow. However, hyporheic zone exchange can be a major hydrogeochemical process in these streams. Depending on landscape position, these streams vary in gradient, channel substrate, biomass abundance, and hyporheic zone extent. This study sampled streams from Taylor, Wright, Garwood, and Miers Valleys and conducted diurnal sampling of two streams of different character in Taylor Valley. In addition, transect sampling was undertaken of the Onyx River in Wright Valley. The δ13CPDB values from these streams span a range of greater than 14‰, from −9.4‰ to +5.1‰, with the majority of samples falling between −3‰ and +2‰, suggesting that the C stable isotope composition of dissolved C in McMurdo Dry Valley streams is largely inorganic in character. Because there are no vascular plants on this landscape and no groundwater input to these streams

  16. Antarctic tourism and the maritime heritage

    OpenAIRE

    Basberg, Bjørn L.

    2008-01-01

    Maritime activity in the Antarctic region goes back to the 18th Century. It evolved from exploration and discoveries to commercial activities, especially sealing and whaling. Antarctic tourism is a more recent phenomenon, developing gradually from the 1960s. Today, more than 20.000 tourists visit the Antarctic annually – mostly on cruise ships. The paper reviews the historical development of these activities. The main focus is on how the maritime heritage has been dealt with an...

  17. Tectonics of the Nazca-Antarctic plate boundary

    Science.gov (United States)

    Anderson-Fontana, Sandra; Larson, Roger L.; Engeln, Joseph F.; Lundgren, Paul; Stein, Seth

    1987-01-01

    A new bathymetric chart of part of the Chile transform system is constructed, based mainly on an R/V Endeavor survey from 100 deg W to its intersection with the East Ridge of the Juan Fernandez microplate. A generally continuous lineated trend can be followed through the entire region, with the transform valley being relatively narrow and well-defined from 109 deg W to approximately 104 deg 30 min W. The fracture zone then widens to the east, with at least two probable en echelon offsets to the south at 104 deg and 102 deg W. Six new strike-slip mechanisms along the Chile Transform and one normal fault mechanism near the northern end of the Chile Rise, inverted together with other plate-motion data from the eastern portion of the boundary, produce a new best-fit Euler pole for the Nazca-Antarctic plate pair, providing tighter constraints on the relative plate motions.

  18. Biologically relevant physical measurements in the ice-free valleys of southern Victoria Land: soil temperature profiles and ultraviolet radiation

    Science.gov (United States)

    Nienow, J. A.; Meyer, M. A.; Friedmann, E. I. (Principal Investigator)

    1986-01-01

    As part of the ongoing comprehensive study of the cryptoendolithic microbial community in the ice-free valleys of southern Victoria Land, thermal properties of the soil and the ultraviolet radiation regime were measured. Although soil temperature profiles have been measured in the ice-free valleys (e.g., Cameron et al. 1970; Cameron 1972), these are the first such data from higher elevations. This is apparently the first time the ultraviolet radiation regime has been measured in the Antarctic.

  19. Antarctic skuas recognize individual humans.

    Science.gov (United States)

    Lee, Won Young; Han, Yeong-Deok; Lee, Sang-Im; Jablonski, Piotr G; Jung, Jin-Woo; Kim, Jeong-Hoon

    2016-07-01

    Recent findings report that wild animals can recognize individual humans. To explain how the animals distinguish humans, two hypotheses are proposed. The high cognitive abilities hypothesis implies that pre-existing high intelligence enabled animals to acquire such abilities. The pre-exposure to stimuli hypothesis suggests that frequent encounters with humans promote the acquisition of discriminatory abilities in these species. Here, we examine individual human recognition abilities in a wild Antarctic species, the brown skua (Stercorarius antarcticus), which lives away from typical human settlements and was only recently exposed to humans due to activities at Antarctic stations. We found that, as nest visits were repeated, the skua parents responded at further distances and were more likely to attack the nest intruder. Also, we demonstrated that seven out of seven breeding pairs of skuas selectively responded to a human nest intruder with aggression and ignored a neutral human who had not previously approached the nest. The results indicate that Antarctic skuas, a species that typically inhabited in human-free areas, are able to recognize individual humans who disturbed their nests. Our findings generally support the high cognitive abilities hypothesis, but this ability can be acquired during a relatively short period in the life of an individual as a result of interactions between individual birds and humans. PMID:26939544

  20. Geophysical Characteristics of the Australian-Antarctic Ridge

    Science.gov (United States)

    Kim, S. S.; Lin, J.; Park, S. H.; Choi, H.; Lee, S. M.

    2014-12-01

    Between 2011 and 2013, the Korea Polar Research Institute (KOPRI) conducted three consecutive geologic surveys at the little explored eastern ends of the Australian-Antarctic Ridge (AAR) to characterize the tectonics, geochemistry, and hydrothermal activity of this intermediate spreading system. Using the Korean icebreaker R/V Araon, the multi-disciplinary research team collected bathymetry, gravity, magnetics, and rock and water column samples. In addition, Miniature Autonomous Plume Recorders (MAPRs) were deployed at wax-core rock sampling sites to detect the presence of active hydrothermal vents. Here we present a detailed analysis of a 300-km-long supersegment of the AAR to quantify the spatial variations in ridge morphology and robust axial and off-axis volcanisms. The ridge axis morphology alternates between rift valleys and axial highs within relatively short ridge segments. To obtain a geological proxy for regional variations in magma supply, we calculated residual mantle Bouguer gravity anomalies (RMBA), gravity-derived crustal thickness, and residual topography for seven sub-segments. The results of the analyses revealed that the southern flank of the AAR is associated with shallower seafloor, more negative RMBA, thicker crust, and/or less dense mantle than the conjugate northern flank. Furthermore, this north-south asymmetry becomes more prominent toward the KR1 supersegment of the AAR. The axial topography of the KR1 supersegment exhibits a sharp transition from axial highs at the western end to rift valleys at the eastern end, with regions of axial highs being associated with more magma supply as indicated by more negative RMBA. We also compare and contrast the characteristics of the AAR supersegment with that of other ridges of intermediate spreading rates, including the Juan de Fuca Ridge, Galápagos Spreading Center, and Southeast Indian Ridge west of the Australian-Antarctic Discordance, to investigate the influence of ridge-hotspot interaction on

  1. Dry Mouth

    Science.gov (United States)

    Dry mouth is the feeling that there is not enough saliva in your mouth. Everyone has a dry mouth once in a while - if they are nervous, ... under stress. But if you have a dry mouth all or most of the time, it can ...

  2. Assessment of trace metals in droppings of Adélie penguins (Pygoscelis adeliae) from different locations of the Antarctic Peninsula area

    Institute of Scientific and Technical Information of China (English)

    Jos E Celis; Winfred Espejo; Ricardo Barra; Daniel Gonzalez-Acua; Francisca Gonzalez; Solange Jara

    2015-01-01

    In recent decades, polar regions of the planet have witnessed an increase in human presence. Antarctica is considered one of the most pristine regions of the world, but it could be affected by pollution owing to anthropogenic activities, particularly in the Antarctic Peninsula. Human presence can increase the levels of some trace metals in Antarctic environments, an issue that needs to be evaluated. To acquire data of trace metal contamination in the Antarctic Peninsula region, concentrations (dry weight) of Cd, Pb, As, Cu, Hg and Zn in fresh excrement of Adélie penguins were determined by atomic absorption spectrophotometry. During the 2012/2013 austral summer, samples were collected from four important nesting sites on the Antarctic Peninsula:Arctowski Base, Kopaitic Island (both sites in the northern Antarctic Peninsula), Yalour Island and Avian Island (both sites in the southern Antarctic Peninsula). Data showed that Adélie penguin excreta had significantly higher levels (mg·kg-1) of As, Cd, Hg, Pb and Cu at Arctowski Base and Kopaitic Island, both sites that have major anthropogenic activities that probably contributed to increased metal levels. The levels of trace metals in Adélie penguins were similar to those reported in excreta of Antarctic species in previous studies, and lower than those in excreta of other Antarctic animals. Data suggest that metals ingested by these penguin species that feed in the sea, end up in terrestrial ecosystems.

  3. Environmental radioactivity in the antarctic station

    International Nuclear Information System (INIS)

    Study about environmental radioactivity in the Peruvian antarctic station Machu Pichu they were carried out during the last three periods to the southern summer. The objective of the project it is to evaluate environmental component in order to elaborate a study it base on the levels background radioactivity and artificial in the antarctic region

  4. Novel long-chain anteiso-alkanes and anteiso-alkanoic acids in Antarctic rocks colonized by living and fossil cryptoendolithic microorganisms

    Science.gov (United States)

    Matsumoto, G. I.; Friedmann, E. I.; Watanuki, K.; Ocampo-Friedmann, R.

    1992-01-01

    Saponified extracts of rock samples colonized by cryptoendolithic microbial communities from the McMurdo Dry Valleys of Southern Victoria Land, Antarctica, were separated into hydrocarbon and fatty acid fractions by silica gel column chromatography. Hydrocarbons and methyl esters of fatty acids were analyzed by capillary gas chromatography-mass spectrometry. Unusually, a suite of long-chain anteiso-alkanes (a-C20 to a-C30) and anteiso-alkanoic acids (a-C20 to a-C30) were detected in many samples, together with straight-chain, branched and/or cyclic and acyclic isoprenoid compounds. These novel compounds are probably derived from unidentified heterotrophic bacteria or symbiotic processes in a unique microbial community in the Antarctic cold desert and suggest the occurrence of a special biosynthetic pathway. Long-chain anteiso-alkanes are probably formed through microbial decarboxylation of corresponding anteiso-alkanoic acids. They may serve as new biomarkers in environmental and geochemical studies.

  5. Valley polarization in bismuth

    Science.gov (United States)

    Fauque, Benoit

    2013-03-01

    The electronic structure of certain crystal lattices can contain multiple degenerate valleys for their charge carriers to occupy. The principal challenge in the development of valleytronics is to lift the valley degeneracy of charge carriers in a controlled way. In bulk semi-metallic bismuth, the Fermi surface includes three cigar-shaped electron valleys lying almost perpendicular to the high symmetry axis known as the trigonal axis. The in-plane mass anisotropy of each valley exceeds 200 as a consequence of Dirac dispersion, which drastically reduces the effective mass along two out of the three orientations. According to our recent study of angle-dependent magnetoresistance in bismuth, a flow of Dirac electrons along the trigonal axis is extremely sensitive to the orientation of in-plane magnetic field. Thus, a rotatable magnetic field can be used as a valley valve to tune the contribution of each valley to the total conductivity. As a consequence of a unique combination of high mobility and extreme mass anisotropy in bismuth, the effect is visible even at room temperature in a magnetic field of 1 T. Thus, a modest magnetic field can be used as a valley valve in bismuth. The results of our recent investigation of angle-dependent magnetoresistance in other semi-metals and doped semiconductors suggest that a rotating magnetic field can behave as a valley valve in a multi-valley system with sizeable mass anisotropy.

  6. Underwater Optics in Sub-Antarctic and Antarctic Coastal Ecosystems

    Science.gov (United States)

    Huovinen, Pirjo; Ramírez, Jaime; Gómez, Iván

    2016-01-01

    Understanding underwater optics in natural waters is essential in evaluating aquatic primary production and risk of UV exposure in aquatic habitats. Changing environmental conditions related with global climate change, which imply potential contrasting changes in underwater light climate further emphasize the need to gain insights into patterns related with underwater optics for more accurate future predictions. The present study evaluated penetration of solar radiation in six sub-Antarctic estuaries and fjords in Chilean North Patagonian region (39–44°S) and in an Antarctic bay (62°S). Based on vertical diffuse attenuation coefficients (Kd), derived from measurements with a submersible multichannel radiometer, average summer UV penetration depth (z1%) in these water bodies ranged 2–11 m for UV-B (313 nm), 4–27 m for UV-A (395 nm), and 7–30 m for PAR (euphotic zone). UV attenuation was strongest in the shallow Quempillén estuary, while Fildes Bay (Antarctica) exhibited the highest transparency. Optically non-homogeneous water layers and seasonal variation in transparency (lower in winter) characterized Comau Fjord and Puyuhuapi Channel. In general, multivariate analysis based on Kd values of UV and PAR wavelengths discriminated strongly Quempillén estuary and Puyuhuapi Channel from other study sites. Spatial (horizontal) variation within the estuary of Valdivia river reflected stronger attenuation in zones receiving river impact, while within Fildes Bay a lower spatial variation in water transparency could in general be related to closeness of glaciers, likely due to increased turbidity through ice-driven processes. Higher transparency and deeper UV-B penetration in proportion to UV-A/visible wavelengths observed in Fildes Bay suggests a higher risk for Antarctic ecosystems reflected by e.g. altered UV-B damage vs. photorepair under UV-A/PAR. Considering that damage repair processes often slow down under cool temperatures, adverse UV impact could be

  7. Carbonate Deposition on Antarctic Shelves

    Science.gov (United States)

    Frank, T. D.; James, N. P.; Malcolm, I.

    2011-12-01

    Limestones associated with glaciomarine deposits occur throughout the geologic record but remain poorly understood. The best-described examples formed during major ice ages of the Neoproterozoic and Late Paleozoic. Quaternary analogs on Antarctic shelves have received comparatively little study. Here, we report on the composition, spatial distribution, and stratigraphic context of carbonate sediments contained in piston cores from the Ross Sea. The goals of this work are to (1) document the nature and distribution of carbonate sediments on the Ross Sea continental shelf and (2) examine temporal relationships to Quaternary glaciation. Results will be used to develop criteria that will improve understanding of analogous deposits in the ancient record. All carbonate-rich intervals in piston cores from the Ross Rea, now housed at the Antarctic Marine Geology Research Facility at Florida State University, were examined and described in detail. Sediment samples were disaggregated and sieved into size fractions before description with paleontological analysis carried out on the coarsest size fraction (>250 microns). Carbonate-rich sediments are concentrated in the northwestern Ross Sea, along the distal margins of Mawson and Pennell Banks. Calcareous facies include a spectrum of lithologies that range from fossiliferous mud, sand, and gravel to skeletal floatstone-rudstone and bafflestone. Floatstone-rudstone and bafflestone is most abundant along western-facing slopes in areas protected from the Antarctic Coastal Current. Sand-prone facies dominate the tops of banks and mud-prone, often spicultic, facies occur in deeper areas. The carbonate factory is characterized by a low-diversity, heterozoan assemblage that is dominated by stylasterine hydrocorals, barnacles, and bryozoans. Molluscs and echinoids are present but not abundant. Planktic and benthic foraminifera are ubiquitous components of the sediment matrix, which is locally very rich in sponge spicules. Biota rarely

  8. Silicon Valley Ecosystem

    Institute of Scientific and Technical Information of China (English)

    Joseph Leu

    2005-01-01

    @@ It is unlikely that any industrial region of the world has received as much scrutiny and study as Silicon Valley. Despite the recent crash of Internet and telecommunications stocks,Silicon Valley remains the world's engine of growth for numerous high-technology sectors.

  9. Rift Valley Fever Virus

    Science.gov (United States)

    Rift Valley fever virus (RVFV) is a mosquito-transmitted virus or arbovirus that is endemic in sub-Saharan Africa. In the last decade, Rift Valley fever (RVF) outbreaks have resulted in loss of human and animal life, as well as had significant economic impact. The disease in livestock is primarily a...

  10. Processing of Antarctic Meteorites at NASA/Johnson Space Center

    Science.gov (United States)

    Satterwhite, C. E.; McBridge, K. M.; Harrington, R. S.; Righter, K.

    2011-01-01

    Since the beginning of the Antarctic Search for Meteorites (ANSMET) program in 1976, over 18,000 meteorites have been processed in the Meteorite Processing Lab at Johnson Space Center in Houston, TX. The first step is to renumber the meteorites from field tag number to generic number and log all the information into the meteorite database. Initial processing involves drying the meteorites in a nitrogen glove box for 24 to 48 hours, photographing, measuring, weighing and writing an exterior description. Next step is to break the meteorite and obtain a good representative sample that will be sent to the Smithsonian institution for classification. Once all the processing is done and the meteorites have been classified, the information is published in the Antarctic meteorite newsletter. The newsletter is published twice yearly and is sent electronically to researchers around the world and is also available on line. Researchers are asked to fill out a request form. The bulk of this paper relates to the researcher's request for meteorite samples.

  11. Denitrification in the Antarctic stratosphere

    Science.gov (United States)

    Salawitch, R. J.; Gobbi, G. P.; Wofsy, S. C.; Mcelroy, M. B.

    1989-01-01

    Rapid loss of ozone over Antarctica in spring requires that the abundance of gaseous nitric acid be very low. Precipitation of particulate nitric acid has been assumed to occur in association with large ice crystals, requiring significant removal of H2O and temperatures well below the frost point. However, stratospheric clouds exhibit a bimodal size distribution in the Antarctic atmosphere, with most of the nitrate concentrated in particles with radii of 1 micron or greater. It is argued here that the bimodal size distribution sets the stage for efficient denitrification, with nitrate particles either falling on their own or serving as nuclei for the condensation of ice. Denitrification can therefore occur without significant dehydration, and it is unnecessary for temperatures to drop significantly below the frost point.

  12. Dry Eye

    Science.gov (United States)

    ... in thyroid disease when the eye protrudes forward; cosmetic surgery, if the eyelids are opened too widely. Frequently ... disease when the eye protrudes forward or after cosmetic surgery if the eyelids are opened too widely, dry ...

  13. Role of the meiobenthos in Antarctic ecosystems

    OpenAIRE

    Vanhove, S.; Wittoeck, J; Beghyn, M.; Van Gansbeke, D.; Van Kenhove, A.; Coomans, A.; Vincx, M.

    1997-01-01

    To date meiobenthic research remained a big white spot in the systematic-ecological work on Antarctic zoobenthos. Therefore the relative importance of the meiofauna (organisms within the size range of 38-1000µm) in the Antarctic benthic community has been assessed by a combined field ecology and experimental approach. This was done in two contrasting conditions, e.g. the deep sea and low subtidal, where as to the depth of the water column the benthic characteristics were, respectively, indire...

  14. 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.

  15. century drying

    Science.gov (United States)

    Cook, Benjamin I.; Smerdon, Jason E.; Seager, Richard; Coats, Sloan

    2014-11-01

    Global warming is expected to increase the frequency and intensity of droughts in the twenty-first century, but the relative contributions from changes in moisture supply (precipitation) versus evaporative demand (potential evapotranspiration; PET) have not been comprehensively assessed. Using output from a suite of general circulation model (GCM) simulations from phase 5 of the Coupled Model Intercomparison Project, projected twenty-first century drying and wetting trends are investigated using two offline indices of surface moisture balance: the Palmer Drought Severity Index (PDSI) and the Standardized Precipitation Evapotranspiration Index (SPEI). PDSI and SPEI projections using precipitation and Penman-Monteith based PET changes from the GCMs generally agree, showing robust cross-model drying in western North America, Central America, the Mediterranean, southern Africa, and the Amazon and robust wetting occurring in the Northern Hemisphere high latitudes and east Africa (PDSI only). The SPEI is more sensitive to PET changes than the PDSI, especially in arid regions such as the Sahara and Middle East. Regional drying and wetting patterns largely mirror the spatially heterogeneous response of precipitation in the models, although drying in the PDSI and SPEI calculations extends beyond the regions of reduced precipitation. This expansion of drying areas is attributed to globally widespread increases in PET, caused by increases in surface net radiation and the vapor pressure deficit. Increased PET not only intensifies drying in areas where precipitation is already reduced, it also drives areas into drought that would otherwise experience little drying or even wetting from precipitation trends alone. This PET amplification effect is largest in the Northern Hemisphere mid-latitudes, and is especially pronounced in western North America, Europe, and southeast China. Compared to PDSI projections using precipitation changes only, the projections incorporating both

  16. Dry cell battery poisoning

    Science.gov (United States)

    Batteries - dry cell ... Acidic dry cell batteries contain: Manganese dioxide Ammonium chloride Alkaline dry cell batteries contain: Sodium hydroxide Potassium hydroxide Lithium dioxide dry cell batteries ...

  17. 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

  18. Blitzen Valley Management Plan

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The 64,000 acre Blitzen Valley unit of Malheur National Wildlife Refuge is not producing enough wildlife to meet the refuge's migratory bird objectives. The area...

  19. Geometry of Valley Growth

    CERN Document Server

    Petroff, Alexander P; Abrams, Daniel M; Lobkovsky, Alexander E; Kudrolli, Arshad; Rothman, Daniel H

    2011-01-01

    Although amphitheater-shaped valley heads can be cut by groundwater flows emerging from springs, recent geological evidence suggests that other processes may also produce similar features, thus confounding the interpretations of such valley heads on Earth and Mars. To better understand the origin of this topographic form we combine field observations, laboratory experiments, analysis of a high-resolution topographic map, and mathematical theory to quantitatively characterize a class of physical phenomena that produce amphitheater-shaped heads. The resulting geometric growth equation accurately predicts the shape of decimeter-wide channels in laboratory experiments, 100-meter wide valleys in Florida and Idaho, and kilometer wide valleys on Mars. We find that whenever the processes shaping a landscape favor the growth of sharply protruding features, channels develop amphitheater-shaped heads with an aspect ratio of pi.

  20. 76 FR 9849 - Comprehensive Environmental Evaluations for Antarctic Activities

    Science.gov (United States)

    2011-02-22

    .... SUPPLEMENTARY INFORMATION: Article 3 of Annex I to the Protocol on Environmental Protection to the Antarctic... Comprehensive Environmental Evaluations for Antarctic Activities SUMMARY: The Department of State gives notice of the availability of two draft Comprehensive Environmental Evaluations (CEEs) for...

  1. Colorful drying.

    Science.gov (United States)

    Lakio, Satu; Heinämäki, Jyrki; Yliruusi, Jouko

    2010-03-01

    Drying is one of the standard unit operations in the pharmaceutical industry and it is important to become aware of the circumstances that dominate during the process. The purpose of this study was to test microcapsulated thermochromic pigments as heat indicators in a fluid bed drying process. The indicator powders were manually granulated with alpha-lactose monohydrate resulting in three particle-size groups. Also, pellets were coated with the indicator powders. The granules and pellets were fluidized in fluid bed dryer to observe the progress of the heat flow in the material and to study the heat indicator properties of the indicator materials. A tristimulus colorimeter was used to measure CIELAB color values. Color indicator for heat detection can be utilized to test if the heat-sensitive API would go through physical changes during the pharmaceutical drying process. Both the prepared granules and pellets can be used as heat indicator in fluid bed drying process. The colored heat indicators give an opportunity to learn new aspects of the process at real time and could be exploded, for example, for scaling-up studies. PMID:20039220

  2. Dry Cleaning

    OpenAIRE

    Shirley, Lindsey; Weller, Chanae

    2010-01-01

    Despite its name, commercial dry cleaning is not actually a “dry” process. Clothes are immersed in a solvent, most commonly perchlorethylene (perc), instead of in water. Perc or other similar solvents are effective in the removal of oil and grease-based stains without damaging or shrinking sensitive fabrics, unlike a regular detergents and fabric softeners.

  3. Meteorological observatory for Antarctic data collection

    International Nuclear Information System (INIS)

    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

  4. The Antarctic cryptoendolithic ecosystem - Relevance to exobiology

    Science.gov (United States)

    Friedmann, E. I.; Ocampo-Friedmann, R.

    1984-01-01

    Cryptoendolithic microorganisms in the Antarctic desert live inside porous sandstone rocks, protected by a thin rock crust. While the rock surface is abiotic, the microclimate inside the rock is comparatively mild. These organisms may have descended from early, pre-glaciation Antarctic life forms and thus may represent the last outpost of life in a gradually deteriorating environment. Assuming that life once arose on Mars, it is conceivable that, following the loss of water, the last of surviving organisms withdrew to similar insulated microenvironments. Because such microscopic pockets have little connection with the outside environment, their detection may be difficult. The chances that the Viking lander could sample cryptoendolithic microorganisms in the Antarctic desert would be infinitesimal.

  5. First geomagnetic measurements in the Antarctic region

    Science.gov (United States)

    Raspopov, O. M.; Demina, I. M.; Meshcheryakov, V. V.

    2014-05-01

    Based on data from literature and archival sources, we have further processed and analyzed the results of geomagnetic measurements made during the 1772-1775 Second World Expedition by James Cook and the 1819-1821 overseas Antarctic Expedition by Russian mariners Bellingshausen and Lazarev. Comparison with the GUFM historical model showed that there are systematic differences in the spatial structure of both the declination and its secular variation. The results obtained can serve as a basis for the construction of regional models of the geomagnetic field for the Antarctic region.

  6. Climate Change Influences on Antarctic Bird Populations

    Science.gov (United States)

    Korczak-Abshire, Małgorzata

    2010-01-01

    Rapid changes in the major environmental variables like: temperature, wind and precipitation have occurred in the Antarctic region during the last 50 years. In this very sensitive region, even small changes can potentially lead to major environmental perturbations. Then the climate change poses a new challenge to the survival of Antarctic wildlife. As important bioindicators of changes in the ecosystem seabirds and their response to the climate perturbations have been recorded. Atmospheric warming and consequent changes in sea ice conditions have been hypothesized to differentially affect predator populations due to different predator life-history strategies and substantially altered krill recruitment dynamics.

  7. Valley-contrasting orbital angular momentum in photonic valley crystals

    CERN Document Server

    Chen, Xiaodong; Dong, Jianwen

    2016-01-01

    Valley, as a degree of freedom, has been exploited to realize valley-selective Hall transport and circular dichroism in two-dimensional layered materials. On the other hand, orbital angular momentum of light with helical phase distribution has attracted great attention for its unprecedented opportunity to optical communicagtions, atom trapping, and even nontrivial topology engineering. Here, we reveal valley-contrasting orbital angular momentum in all-dielectric photonic valley crystals. Selective excitation of valley chiral bulk states is realized by sources carrying orbital angular momentum with proper chirality. Valley dependent edge states, predictable by nonzero valley Chern number, enable to suppress the inter-valley scattering along zigzag boundary, leading to broadband robust transmission in Z-shape bend without corner morphological optimization. Our work may open up a new door towards the discovery of novel quantum states and the manipulation of spin-orbit interaction of light in nanophotonics.

  8. [Anatomical and nutrient features of plant leaves in Yuanjiang savanna valley].

    Science.gov (United States)

    Song, Fuqiang; Cao, Kunfang

    2005-01-01

    Due to rain shadow effect, the valleys in southwestern China mountainous areas have hot and dry climate, and savanna or semi-savanna vegetations occur on the slopes of these valleys. Yuanjiang dry-hot valley is such a valley, which has a distinct dry season of about six months from November to next April. This paper studied the anatomical and nutrient features of the leaves of twenty plant species, including those on upland soils and hilly slopes. The results showed that compared with the species on upland soil and the rain forest, the leaves of the plants from savanna showed more xeromorphic features, such as thicker leaf thickness, greater leaf mass per area (LMA), smaller ratios of spongy/palisade tissues (S:P) and higher stomatal density (SD), which mainly came from the more severe drought in Yuanjiang savanna valley. Seven plant species in the savanna valley showed a shortage of nutrients in their leaves, and the leaf nutrient content was in order of 1.3% > Ca > N > K > 1% > Mg > P > S. Savanna had lower leaf mineral element concentrations than rain forest, but higher than other dry forests, including Asian heath forest and Bana forest. The differences in leaf nutrient concentrations between Yuanjiang valley savanna and other dry forests were mainly ascribed to the difference of soil nutrient contents, while those between valley savanna and rainforest were largely determined by the different plant biology. It could be concluded that the leaves of plant species in Yuanjiang savanna valley not only had obvious xeromorphic features, but also were deficit in nutrients. PMID:15852953

  9. Drying apparatus

    International Nuclear Information System (INIS)

    Particulate material, eg. fuel pellets for a nuclear reactor, is moved along a spiral path during drying by vibration of the path structure. Preferred apparatus comprises a hollow cone with a conical flight defining a path of travel having an inlet for the material and an outlet. The cone is heated by a radiant heater within the cone which itself is vibrated or oscillated about column. A cone provides an air space in which air can circulate and leave by convection through chimney. The flight may have a pile providing a fibrous surface for engaging the material. (author)

  10. Contrasting Arctic and Antarctic sea ice temperatures

    Science.gov (United States)

    Vancoppenolle, Martin; Raphael, Marilyn; Rousset, Clément; Vivier, Frédéric; Moreau, Sébastien; Delille, Bruno; Tison, Jean-Louis

    2016-04-01

    Sea ice temperature affects the sea ice growth rate, heat content, permeability and habitability for ice algae. Large-scale simulations with NEMO-LIM suggest large ice temperature contrasts between the Arctic and the Antarctic sea ice. First, Antarctic sea ice proves generally warmer than in the Arctic, in particular during winter, where differences reach up to ~10°C. Second, the seasonality of temperature is different among the two hemispheres: Antarctic ice temperatures are 2-3°C higher in spring than they are in fall, whereas the opposite is true in the Arctic. These two key differences are supported by the available ice core and mass balance buoys temperature observations, and can be attributed to differences in air temperature and snow depth. As a result, the ice is found to be habitable and permeable over much larger areas and much earlier in late spring in the Antarctic as compared with the Arctic, which consequences on biogeochemical exchanges in the sea ice zone remain to be evaluated.

  11. Relevance of antarctic microbial ecosystems to exobiology

    Science.gov (United States)

    Mckay, Christopher P.

    1993-01-01

    Antarctic microbial ecosystems which provide biological and physical analogs that can be used in exobiology are studied. Since the access to extraterrestrial habitats is extremely difficult, terrestrial analogs represent the best opportunity for both formulation and preliminary testing of hypothesis about life. Antarctica, as one of few suitable environments on earth is considered to be a major locus of progress in exobiology.

  12. The East Antarctic Ice Sheet and the Gamburtsev Subglacial Mountains (Invited)

    Science.gov (United States)

    Bell, R. E.; Studinger, M.; Ferraccioli, F.; Damaske, D.; Finn, C.; Braaten, D. A.; Fahnestock, M. A.; Jordan, T. A.; Corr, H.; Elieff, S.; Frearson, N.; Block, A. E.; Rose, K.

    2009-12-01

    Models of the onset of glaciation in Antarctica routinely document the early growth of the ice sheet on the summit of the Gamburtsev Subglacial Mountains in the center of the East Antarctic Craton. While ice sheet models replicate the formation of the East Antarctic ice sheet 35 million years ago, the age, evolution and structure of the Gamburtsev Mountains remain completely unresolved. During the International Polar Year scientists from seven nations have launched a major collaborative program (AGAP) to explore the Gamburtsev Subglacial Mountains buried by the East Antarctic ice sheet and bounded by numerous subglacial lakes. The AGAP umbrella is a multi-national, multi-disciplinary effort and includes aerogeophysics, passive seismology, traverse programs and will be complimented by future ice core and bedrock drilling. A major new airborne data set including gravity; magnetics; ice thickness; SAR images of the ice-bed interface; near-surface and deep internal layers; and ice surface elevation is providing insights into a more dynamic East Antarctica. More than 120,000 km of aerogeophysical data have been acquired from two remote field camps during the 2008/09 field season. AGAP effort was designed to address several fundamental questions including: 1) What role does topography play in the nucleation of continental ice sheets? 2) How do tectonic processes control the formation, distribution, and stability of subglacial lakes? The preliminary analysis of this major new data set indicated these 3000m high mountains are deeply dissected by a dendritic system. The northern margin of the mountain range terminates against the inland extent of the Lambert Graben. Evidence of the onset of glaciation is preserved as cirques and U shaped valleys along the axis of the uplifted massifs. The geomorphology reflects the interaction between the ice sheet and the Gamburtsev Mountains. Bright reflectors in the radar data in the deep valleys indicate the presence of water that has

  13. Neogene kinematic history of Nazca-Antarctic-Phoenix slab windows beneath Patagonia and the Antarctic Peninsula

    Science.gov (United States)

    Breitsprecher, Katrin; Thorkelson, Derek J.

    2009-01-01

    The Patagonian slab window is a subsurface tectonic feature resulting from subduction of the Nazca-Antarctic spreading-ridge system (Chile Rise) beneath southern South America. The geometry of the slab window had not been rigorously defined, in part because of the complex nature of the history of ridge subduction in the southeast Pacific region, which includes four interrelated spreading-ridge systems since 20 Ma: first, the Nazca-Phoenix ridge beneath South America, then simultaneous subduction of the Nazca-Antarctic and the northern Phoenix-Antarctic spreading-ridge systems beneath South America, and the southern Phoenix-Antarctic spreading-ridge system beneath Antarctica. Spreading-ridge paleo-geographies and rotation poles for all relevant plate pairs (Nazca, Phoenix, Antarctic, South America) are available from 20 Ma onward, and form the mathematical basis of our kinematic reconstruction of the geometry of the Patagonia and Antarctic slab windows through Neogene time. At approximately 18 Ma, the Nazca-Phoenix-Antarctic oceanic (ridge-ridge-ridge) triple junction enters the South American trench; we recognize this condition as an unstable quadruple junction. Heat flow at this junction and for some distance beneath the forearc would be considerably higher than is generally recognized in cases of ridge subduction. From 16 Ma onward, the geometry of the Patagonia slab window developed from the subduction of the trailing arms of the former oceanic triple junction. The majority of the slab window's areal extent and geometry is controlled by the highly oblique (near-parallel) subduction angle of the Nazca-Antarctic ridge system, and by the high contrast in relative convergence rates between these two plates relative to South America. The very slow convergence rate of the Antarctic slab is manifested by the shallow levels achieved by the slab edge (< 45 km); thus no point on the Antarctic slab is sufficiently deep to generate "normal" mantle-derived arc-type magmas

  14. Breathing Valley Fever

    Centers for Disease Control (CDC) Podcasts

    2014-02-04

    Dr. Duc Vugia, chief of the Infectious Diseases Branch in the California Department of Public Health, discusses Valley Fever.  Created: 2/4/2014 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 2/5/2014.

  15. Silicon Valley's Turnaround

    Institute of Scientific and Technical Information of China (English)

    Joseph Leu

    2006-01-01

    @@ During Silicon Valley's dramatic economic growth fueled by the Internet boom and business investment in information technology, employment in the region's high-tech sec tor tripled between 1995 and 2000. The economic boom gave rise to many new firms,drawing em ployees into high-tech jobs from other regions and other industries.

  16. Silicon Valley Policy

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Silicon Valley is home to the most dynamic industries in the California economy. These industries--the high-tech sector--are driven by innovation, and each new wave of innovation is usually led by creative entrepreneurs starting new firms.

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

    International Nuclear Information System (INIS)

    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).

  18. Temperature, lithosphere-asthenosphere boundary, and heat flux beneath the Antarctic Plate inferred from seismic velocities

    Science.gov (United States)

    An, Meijian; Wiens, Douglas A.; Zhao, Yue; Feng, Mei; Nyblade, Andrew; Kanao, Masaki; Li, Yuansheng; Maggi, Alessia; Lévêque, Jean-Jacques

    2015-12-01

    We estimate the upper mantle temperature of the Antarctic Plate based on the thermoelastic properties of mantle minerals and S velocities using a new 3-D shear velocity model, AN1-S. Crustal temperatures and surface heat fluxes are then calculated from the upper mantle temperature assuming steady state thermal conduction. The temperature at the top of the asthenosphere beneath the oceanic region and West Antarctica is higher than the dry mantle solidus, indicating the presence of melt. From the temperature values, we generate depth maps of the lithosphere-asthenosphere boundary and the Curie temperature isotherm. The maps show that East Antarctica has a thick lithosphere similar to that of other stable cratons, with the thickest lithosphere (~250 km) between Domes A and C. The thin crust and lithosphere beneath West Antarctica are similar to those of modern subduction-related rift systems in East Asia. A cold region beneath the Antarctic Peninsula is similar in spatial extent to that of a flat-subducted slab beneath the southern Andes, indicating a possible remnant of the Phoenix Plate, which was subducted prior to 10 Ma. The oceanic lithosphere generally thickens with increasing age, and the age-thickness correlation depends on the spreading rate of the ridge that formed the lithosphere. Significant flattening of the age-thickness curves is not observed for the mature oceanic lithosphere of the Antarctic Plate.

  19. Dry Mouth or Xerostomia

    Science.gov (United States)

    ... or Xerostomia Request Permissions Print to PDF Dry Mouth or Xerostomia Approved by the Cancer.Net Editorial ... a dry mouth. Signs and symptoms of dry mouth The signs and symptoms of dry mouth include ...

  20. Zinder: a city running dry.

    Science.gov (United States)

    Price, T

    1993-01-01

    In the West African Sahel lies the old Hausa city of Zinder, Niger. Since the last few decades, it has constantly faced considerable population growth (19,300-119,8000 between 1960 and 1980) while its acute problems with the water supply are increasing. The dry regional climate compounds the problems. In the past, Zinder was a trade center between northern and sub-Saharan Africa as well as being the colonial capital of Niger (1911-26). Its economic and political position has fallen greatly with independence. Lower than average rainfall and the disastrous droughts of the 1970s and 1980s have seriously diminished the region's economic base, e.g., the average annual rainfall in 1930-60 was 535 mm, but by the 1980s, it was only 355 mm. Zinder sits on an elevated, rocky hill which is encircled by dry river valleys and there are no major permanent bodies of water in the vicinity. Impenetrable layers of stone prevent the digging of wells within the city, so the city depends on wells in nearby valleys. The reduced rainfall hinders replenishment of the aquifer, resulting in a drop in the availability of water for daily consumption from 6500 to 3500 sq m. Per capita water consumption in Zinder is much lower than the national average (55 1/day vs. about 100 1/day). The drought in 1992 caused per capita consumption to fall to 29 1/day, just barely above the minimal standards for private use in urban areas of 20 1/person/day. To further compound the problem, 20 villages in Zinder's environs, some villages with a population of 5000, people, rely on the same water system. Zinder serves as a refuge for the regional population in drought years and during the yearly dry season. Promised international financing cannot resolve Zinder's problems at a realistic cost. PMID:12287010

  1. Does Antarctic glaciation cool the world?

    Directory of Open Access Journals (Sweden)

    A. Goldner

    2012-07-01

    Full Text Available In this study we compare the simulated climatic impact of adding the Antarctic Ice Sheet to the "Greenhouse World" of the Eocene and removing the Antarctic Ice Sheet from the Modern world. The Modern surface temperature anomaly (ΔT induced by Antarctic Glaciation ranges from −1.22 to −0.18 K when CO2 is dropped from 2240 to 560 ppm, whereas the Eocene ΔT is nearly constant at −0.3 K. We calculate the climate sensitivity parameter S[Antarctica] which is defined as the change in surface temperature (ΔT divided by the change in radiative forcing (ΔQAntarctica imposed by prescribing the glacial properties of Antarctica. While the ΔT associated with the imposed Antarctic properties is relatively consistent across the Eocene cases, the radiative forcing is not. This leads to a wide range of S[Antarctica], with Eocene values systematically smaller than Modern.

    This differing temperature response in Eocene and Modern is partially due to the smaller surface area of the imposed forcing over Antarctica in the Eocene and partially due to the presence of strong positive sea-ice feedbacks in the Modern. The system's response is further mediated by differing shortwave cloud feedbacks which are large and of opposite sign operating in Modern and Eocene configurations. A negative cloud feedback warms much of the Earth's surface as a large ice sheet is introduced in Antarctica in the Eocene, whereas in the Modern this cloud feedback is positive and acts to enhance cooling introduced by adding an ice sheet. Because of the importance of cloud feedbacks in determining the final temperature sensitivity of the Antarctic Ice Sheet our results are likely to be model dependent. Nevertheless, these model results show that the radiative forcing and feedbacks induced by the Antarctic Ice Sheet did not significantly decrease global mean surface temperature across

  2. Onset and role of the Antarctic Circumpolar Current

    OpenAIRE

    Barker, P. F.; Threshers Barn, Whitcott Keysett, Clun, Shropshire SY7 8QE, UK; Filippelli, G. M.; Department of Earth Sciences, Indiana University-Purdue University Indianapolis (IUPUI), Indianapolis, IN 46202-5132, USA; Florindo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Martin, E. E.; Department of Geological Sciences, University of Florida, Gainesville, FL 32611-2120, USA; Howard, D. S.; Department of Earth & Environmental Sciences, University of Rochester, Rochester, NY 14611, USA

    2007-01-01

    For some time, onset of the Antarctic Circumpolar Current (ACC) was considered to have caused or stabilised full Antarctic glaciation. Recently, however, the importance of the ACC in this role has been questioned. In order to understand the relationship between the ACC and Antarctic glaciation, and thence the importance of ocean circulation to palaeoclimate, we need to determine the development history of both processes. To this end, we summarise all published estimates of ACC ons...

  3. Relative Changes in Krill Abundance Inferred from Antarctic Fur Seal

    OpenAIRE

    Tao Huang; Liguang Sun; John Stark; Yuhong Wang; Zhongqi Cheng; Qichao Yang; Song Sun

    2011-01-01

    Antarctic krill Euphausia superba is a predominant species in the Southern Ocean, it is very sensitive to climate change, and it supports large stocks of fishes, seabirds, seals and whales in Antarctic marine ecosystems. Modern krill stocks have been estimated directly by net hauls and acoustic surveys; the historical krill density especially the long-term one in the Southern Ocean, however, is unknown. Here we inferred the relative krill population changes along the West Antarctic Peninsula ...

  4. On the Atmospheric Correction of Antarctic Airborne Hyperspectral Data

    OpenAIRE

    Martin Black; Andrew Fleming; Teal Riley; Graham Ferrier; Peter Fretwell; John McFee; Stephen Achal; Alejandra Umana Diaz

    2014-01-01

    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 reflectan...

  5. Surface influence on the marine and coastal Antarctic atmosphere

    OpenAIRE

    Valkonen, Teresa

    2013-01-01

    The Antarctic region plays an important role in the global climate system, and it contributes to the future of global climate through changes in regional factors, such as sea ice, atmospheric circulation patterns and moisture distribution. The aim of this thesis is to improve the understanding of the influence of the Earth surface on the marine and coastal Antarctic atmosphere. The thesis outlines the characteristics of typical phenomena of the Antarctic environment both near the surface and ...

  6. Encouraging Advances Made by Chinese Scientists in Antarctic Research

    Institute of Scientific and Technical Information of China (English)

    Zhang Qingsong

    2003-01-01

    @@ Chinese scientists began involving in the Antarctic research in 1980. As the first step, some 40 Chinese scientists were sent to Antarctic stations of Australia and other countries during the period from 1980 to 1984. Then,China established two Antarctic stations of its own, and purchased an icebreaker, enabling China to carry on its own independent research program both on land and at sea.

  7. Terrestrial age dating of antarctic meteorites

    International Nuclear Information System (INIS)

    During the last three antarctic field seasons, US and Japanese teams have collected several thousand meteorites. The terrestrial age of these objects is of interest because such knowledge enables the setting of lower bounds on the lower age of the ice sheet, provides information about ice movement, and aids understanding of the accumulation mechanism of the meteorites. Terrestrial ages can be established by measuring the decay of radioactive species produced by bombardment of cosmic rays while the objects are in space. After entering the Earth's atmosphere the meteorites essentially are completely shielded from cosmic rays. The radioactive products that exist at saturation values in space then decay exponentially toward zero activity. By the end of 1980, data will be established on 150 to 200 selected samples. With that large a data base we should have a fairly clear picture of the terrestrial age distribution of antarctic meteorites

  8. [Taxonomical status of the psychrotolerant Antarctic microorganisms].

    Science.gov (United States)

    Romanovskaia, V A; Gladka, G V; Tashireva, A A; Tashirev, A B

    2013-01-01

    The aerobic chemoorganotrophic bacteria, dominating in soils and phytocenosis of the Antarctic Region, on combination of morphological and biochemical properties belong to several taxons of Bacteria domain. Gram-negative strains 3189, 3415 (fam. Halomonadaceae, Halomonas sp.) and 3088, 3468, 3469 (fam. Moraxellaceae, Psychrobacter sp.) belong to phylum Proteobacteria, to class Gammaproteobacteria. Gram-negative strains 3294 3392 (Rhizobiales, fam. Methylobacteriaceae, Methylobacterium sp.) relate to class Alphaproteobacteria of this phylum. Gram-positive strains 3179, 3275, 3470, 3471 (fam. Microbacteriaceae, Cryobacterium sp.), 3054, 3058, 3411 (fam. Corynebacteriaceae, Corynebacterium sp.) and 3194, 3398 (fam. Micrococcaceae, Micrococcus sp.) relate to phylum Actinobacteria, class Actinobacteria. Thus, the psychrophilic and psychrotolerant Antarctic bacteria (aerobic chemoorganotrophic) isolated from phytocenosis and soils of polar region are characterized by wide taxonomic variety. PMID:24450178

  9. Green valley galaxies

    Directory of Open Access Journals (Sweden)

    Salim S.

    2014-01-01

    Full Text Available The “green valley” is a wide region separating the blue and the red peaks in the ultraviolet-optical color magnitude diagram, first revealed using GALEX UV photometry. The term was coined by Christopher Martin (Caltech, in 2005. Green valley highlights the discriminating power of UV to very low relative levels of ongoing star formation, to which the optical colors, including u−r, are insensitive. It corresponds to massive galaxies below the star-forming, “main” sequence, and therefore represents a critical tool for the study of the quenching of star formation and its possible resurgence in otherwise quiescent galaxies. This article reviews the results pertaining to (predominantly disk morphology, structure, environment, dust content and gas properties of green valley galaxies in the local universe. Their relationship to AGN is also discussed. Attention is given to biases emerging from defining the “green valley” using optical colors. We review various evolutionary scenarios and we present evidence for a new one, the quasi-static view of the green valley, in which the majority (but not all of galaxies currently in the green valley were only partially quenched in the distant past and now participate in a slow cosmic decline of star formation, which also drives down the activity on the main sequence, presumably as a result of the dwindling accretion/cooling onto galaxy disks. This emerging synthetic picture is based on the findings from Fang et al. (2012, Salim et al. (2012 and Martin et al. (2007, as well as other results.

  10. Revitalizing the Mahoning Valley

    OpenAIRE

    T F Buss; Vaughan, R J

    1987-01-01

    For nearly a decade, since the closing of its steel mills, the Mahoning Valley in northeast Ohio has pursued a traditional development strategy, based upon large capital subsidies, to attract new or support existing businesses. These policies have failed. As a result, local business leaders have questioned the foundations of traditional policy and have developed an alternative strategy that involves a far broader set of state and local programs in the development process. The new strategy aim...

  11. Antarctic terrestrial ecosystems: responses to environmental change

    OpenAIRE

    Convey, Peter

    2006-01-01

    The consequences of climate change are exciting considerable concern worldwide. Parts of Antarctica are facing the most rapid rates of anthropogenic climate change currently seen on the planet. This paper sets out to introduce contemporary ecosystems of the Antarctic, and the factors that have influenced them and their biodiversity over evolutionary timescales. Contemporary climate change processes significant to terrestrial biota, and the biological consequences of these changes seen t...

  12. Isotopic heterogeneity of East Antarctic mantle

    International Nuclear Information System (INIS)

    Isotopic heterogeneity of deep garnet-bearing mantle xenolytes of East Antarctics is studied to analyze the mechanisms of geochemical heterogeneity occurrence in the Earth mantle. Analysis of isotope data for the system 143Nd/144Nd - Sm/Nd permitted ascertaining the time of the last thermal impact on the mantle material (108-35 bill. years) for certain nodules, which is close to the age of ultra base alkali magmatism intrusion

  13. Photosynthesis in Antarctic sea ice diatoms

    OpenAIRE

    Mock, Thomas

    2003-01-01

    This thesis was conducted to apply new techniques for measuring photosynthesis in Antarctic sea ice diatoms. A systematic approach of investigations was applied to obtain precise measurements of photosynthesis under natural conditions in the field from which questions were derived for further analysis in the laboratory. In situ measurements with the tracer 14C through the entire thickness of a young sea ice floe revealed that algae are able to actively assimilate dissolved inorganic carbon un...

  14. Oil Pollution in the Antarctic Terrestrial Environment

    OpenAIRE

    Hughes, Kevin; Stallwood, Bethan

    2006-01-01

    Fuel oil has been extensively relied upon as an energy source since the earliest discovery and exploration of Antarctica. During this time oil spills have occurred, particularly around established research stations, which have had a negative impact on the terrestrial environment. Recently developed bioremediative technology, using indigenous Antarctic hydrocarbon-degrading bacteria, may be used to assist in cleaning up existing oil-contaminated land

  15. Satellite magnetic anomalies of the Antarctic crust

    Directory of Open Access Journals (Sweden)

    D. E. Alsdorf

    2000-06-01

    Full Text Available Spatially and temporally static crustal magnetic anomalies are contaminated by static core field effects above spherical harmonic degree 12 and dynamic, large-amplitude external fields. To extract crustal magnetic anomalies from the measurements of NASA's Magsat mission, we separate crustal signals from both core and external field effects. In particular, we define Magsat anomalies relative to the degree 11 field and use spectral correlation theory to reduce them for external field effects. We obtain a model of Antarctic crustal thickness by comparing the region's terrain gravity effects to free-air gravity anomalies derived from the Earth Gravity Model 1996 (EGM96. To separate core and crustal magnetic effects, we obtain the pseudo-magnetic effect of the crustal thickness variations from their gravity effect via Poisson's theorem for correlative potentials. We compare the pseudo-magnetic effect of the crustal thickness variations to field differences between degrees 11 and 13 by spectral correlation analysis. We thus identify and remove possible residual core field effects in the Magsat anomalies relative to the degree 11 core field. The resultant anomalies reflect possible Antarctic contrasts due both to crustal thickness and intracrustal variations of magnetization. In addition, they provide important constraints on the geologic interpretation of aeromagnetic survey data, such as are available for the Weddell Province. These crustal anomalies also may be used to correct for long wavelength errors in regional compilations of near-surface magnetic survey data. However, the validity of these applications is limited by the poor quality of the Antarctic Magsat data that were obtained during austral Summer and Fall when south polar external field activity was maximum. Hence an important test and supplement for the Antarctic crustal Magsat anomaly map will be provided by the data from the recently launched Ørsted mission, which will yield coverage

  16. PSEUDO MAGNETIC ANOMALIES IN THE ANTARCTIC SEA

    OpenAIRE

    マツモト, タケシ; カミヌマ, カツタダ; Takeshi, MATSUMOTO; Katsutada, Kaminuma

    1988-01-01

    Pseudo magnetic anomaly in the Antarctic Sea has been calculated using the gravity data derived from altimetric geoid. Comparison of the pseudo magnetic anomaly thus calculated with the theoretical magnetic anomaly predicted from topography has been made with respect to the large fracture zones composed of short-wavelength ridges and troughs in the Southeastern Pacific, which shows that these two anomalies coincide well with each other. Gravity anomaly calculated from topography only also coi...

  17. Tephrochronology : Methodology and correlations, Antarctic Peninsula Area

    OpenAIRE

    Molén, Mats

    2012-01-01

    Abstract Methods for tephrochronology are evaluated, in the following way: Lake sediments <500 years old from three small Antarctic lakes were analysed for identification of tephras. Subsamples were analysed for a) grain size, and identification and concentration of volcanogenic grains, b) identification of tephra horizons, c) element abundance by EPMA WDS/EDS and LA-ICP-MS, and d) possible correlations between lakes and volcanoes. Volcanogenic minerals and shards were found all through th...

  18. 元谋干热河谷坡面径流蓄积过程中的面源污染物变化%Change of Non-Point Pollutant During the Accumulation Process of Slope Runoff in the Dry-Hot Valley in Yuanmou County

    Institute of Scientific and Technical Information of China (English)

    王建文; 王克勤; 任占远; 陈全芳

    2012-01-01

    在元谋干热河谷选择严重干扰退化草地、采取“封禁”和“封禁+等高反坡阶”植被自然恢复草地,布设集水系统对3种草地的径流进行拦截和蓄积,并对2008年雨季和之后的地表径流总氮、总磷和化学需氧量浓度进行测定,结果表明:自然恢复植被能大量减少坡面径流和泥沙产生量,进而大幅度减少面源污染物的输出.坡面径流收集过程对径流拦截和沉砂过程中面源污染物的浓度有较大的削减作用,径流从沉砂池进入蓄水设备,使总氮和总磷浓度分别削减46.63%和38.08%,地表径流在蓄水设备中贮存会使径流中的面源污染物浓度得到进一步削减,证明水土流失防治措施在削减面源污染物输出中有显著作用.%The 'grazing closure' and 'grazing closure + anti-slope contour stairs' measures integrated with water harvesting engineering were conducted on 3 types of severely degraded meadows to intercept and gather runoff in Yuanmou dry-hot valley in order to promote the natural recovery of the grass vegetation. The total nitrogen content (TN) , total phosphorous content (TP) , and chemical oxygen demand (COD) of the slope runoff in the rainy season and later on in the dry season of 2008 were determined. The results showed that restoration of the natural vegetation could greatly reduce the slope runoff and soil erosion, so as to greatly reduce the output of non-point pollutant. The slope runoff collection process included runoff interception and sand sedimentation that could significantly reduce the concentration of the non-point pollutants. It was showed by the study that the concentration of TN and TP was deducted by 46. 63% and 38. 08% respectively in the course while the runoff flowed from the sand setting pound into the impounding basin. The concentration of the non-point pollutants in the runoff water storage system could be further reduced, so it was demonstrated that the soil and water erosion

  19. New and rare cephalopods from the Antarctic waters

    OpenAIRE

    Kubodera,Tsunemi/Okutani,Takeshi

    1986-01-01

    Three species of Antarctic cephalopods, Grimpoteuthis antarctica n. sp., male specimens of Megaleledone senoi TAKI and Gonatus antarcticus LONNBERG are described with some considerations to their systematic status.

  20. Dating Antarctic soils using atmosphere-derived 10Be and nitrate

    International Nuclear Information System (INIS)

    Because they are slow forming, Antarctic soils have the potential to yield considerable climatic information from the past c.20 m.y. However, these soils have proved difficult to date absolutely by conventional means. Here we present a novel approach to the problem, based on atmosphere-derived 10Be and nitrate contents. In situations where medium to long term deposition rates can be reasonably estimated from ice core data, the total nitrate inventory in an Antarctic soil can place constraints on its formation age. 10Be radioactive decay may then be used, assuming steady state equilibrium, to further refine the age profile. We have applied such models to a complex soil from the Taylor Valley region in South Victoria Land, deriving an overall nitrate inventory age of c. 18 Ma, and 10Be decay ages for the upper and middle layers of c.15 and c.17 Ma, respectively. These results are consistent with the >10 Ma age of the soil deduced from stratigraphic and geomorphological information. (author). 28 refs., 4 figs., 2 tabs

  1. Measurements of 36Cl in Antarctic meteorites and Antarctic ice using a Van de Graaff accelerator

    International Nuclear Information System (INIS)

    Cosmic-ray produced 36Cl(tsub(1/2) = 3.0 X 105 years) has been measured in four Antarctic meteorites and one sample of Antarctic ice using a tandem Van de Graaff accelerator as an ultrasensitive mass spectrometer with the extremely low background level of 36Cl/Cl -16. Results from this ion counting technique (applied here to extraterrestrial materials for the first time) are used to support a two-stage irradiation model for the Yamato-7301and Allan Hills-76008 meteorites and to show a long terrestrial age (0.7 +- 0.1 m.y.) for Allan Hills-77002. Yamato-7304 has a terrestrial age of less than 0.1 m.y. The 36Cl content of the Antarctic ice sample from the Yamato Mountain area implies that the age of the ice cap at this site is less than one 36Cl half-life. (Auth.)

  2. 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

  3. Skip spawning as a reproductive strategy in Antarctic fish species: the Antarctic silverfish (Pleuragramma antarctica) case study

    OpenAIRE

    Eva Pisano; Stuart Hanchet; Marino Vacchi

    2015-01-01

    The Antarctic silverfish Pleuragramma antarctica (Notothenioidei, Nototheniidae) is the most abundant pelagic fish inhabiting the frigid Antarctic coastal waters. It plays relevant roles in the local ecosystems, where it is often considered a keystone species connecting lower and upper trophic levels within the coastal marine food web. Despite its ecological relevance, and although many aspects of the Antarctic silverfish biology have already been elucidated, knowledge on important components...

  4. The ARM West Antarctic Radiation Experiment (AWARE)

    Science.gov (United States)

    Lubin, Dan; Bromwich, David; Vogelmann, Andrew; Verlinde, Johannes; Russell, Lynn

    2016-04-01

    West Antarctica is one of the most rapidly warming regions on Earth, and its changing climate in both atmosphere and ocean is linked to loss of Antarctic ice mass and global sea level rise. The specific mechanisms for West Antarctic Ice Sheet (WAIS) warming are not fully understood, but are hypothesized to involve linkage between moisture from Southern Ocean storm tracks and the surface energy balance over the WAIS, and related teleconnections with subtropical and tropical meteorology. This present lack of understanding has motivated a climate science and cloud physics campaign jointly supported by the US National Science Foundation (NSF) and Department of Energy (DOE), called the Atmospheric Radiation Measurement Program (ARM) West Antarctic Radiation Experiment (AWARE). The DOE's second ARM Mobile Facility (AMF2) was deployed to McMurdo Station on Ross Island in November 2015 and will operate through December 2016. The AMF2 includes (1) cloud research radars, both scanning and zenith, operating in the Ka- and X-bands, (2) high spectral resolution and polarized micropulse lidars, and (3) a suite of shortwave and longwave broadband and spectral radiometers. A second suite of instruments is deployed at the WAIS Divide Ice Camp on the West Antarctic plateau during December 2015 and January 2016. The WAIS instrument suite provides (1) measurement of all surface energy balance components, (2) a polarized micropulse lidar and shortwave spectroradiometer, (3) microwave total water column measurement, and (4) four times daily rawinsonde launches which are the first from West Antarctica since 1967. There is a direct linkage between the WAIS instrument suite and the AMF2 at McMurdo, in that air masses originating in Southern Ocean storm tracks that are driven up over the WAIS often subsequently descend over the Ross Ice Shelf and arrive at Ross Island. Preliminary data are already illustrating the prevalence of mixed-phase clouds and their role in the surface energy balance

  5. Ethno-Botanical Study of Medicinal Plants of Paddar Valley of Jammu and Kashmir, India

    OpenAIRE

    Gupta, Sushil Kumar; Sharma, Om Prakash; Raina, Narinder Singh; Sehgal, Sandeep

    2013-01-01

    The Paddar Valley, historically known as Sapphire Valley situated in Kishtwar district, is a prime landmark in the Jammu region of J&K state and is known for its rich cultural and plant diversity because of diverse habitats such as rivers, streams, meadows and steep mountain slopes. The area is located in the dry temperate region comprising typical vegetation which disappears completely on the eastern slopes, dominated by a variety of economical species which play an important role in the rur...

  6. Effects of Habitat Heterogeneity on Early Growth of Quercus franchetii Natural Regeneration Seedlings in the Jinsha River Dry-hot Valley%生境异质性对金沙江干热河谷锥连栎天然更新幼苗早期生长的影响

    Institute of Scientific and Technical Information of China (English)

    刘方炎; 张志翔; 王小庆; 李昆; 孙永玉; 张春华

    2011-01-01

    Quercus franchetii forest is one of the very important natural vegetations in dry-hot valley of the Jinsha River. China. Now it is very difficult for seedling natural regeneration because of serious habitat fragmentation resulting from bad climatic environment and long-term serious human disturbance. Seedlings in the Q. Franchetii forest are mainly located at low land covered by litter (LLCL), flat ground covered by litter (FGCL), terrace along water ditch (TAWD) and grassland in gentle slope (GGS). To know the seedling growth characteristics in different microhabitats and the best microhabitat for seedlings to settle down in natural forests, the characteristics of the four microhabitats were investigated, and the morphological characteristics, biomass allocation and survival status of the seedlings growing in different micro-habitats were studied comparatively. The results showed that there were obviously different among 4 microhabitats in depth of soil and defoliation, and surface soil water content in different seasons, especially in dry season. Of number of seedlings, LLCL > TAWD > FGCL > GGS. Of seedling morphologic characteristics, significant differences were mainly in seedling height, main root length and specific leaf area (SLA), while slight differences in basal diameter and number of leaves. The seedlings growing in LLCL and GGS respectively had the maximum and the minimum values of seedling height, basal diameter, main root length and number of leaves. Of SLA, LLCL > TAWD > FGCL > GGS. There were extremely significant differences among different microhabitats in dry biomasses of seedlings, aboveground and underground parts, ratios of root and stem. Of ratio of root andstem, GGS > TAWD > FGCL > LLCL, and of dry biomass of seedlings, LLCL > FGCL > TAWD > GGS. There was obviously different among different microhabitats in survival status of the seedlings in dry season, and the dead seedlings and stem- or leaf-withered seedlings occupied 69.2%~95.2%. The

  7. Geoethical Approach to Antarctic Subglacial Lakes Exploration

    Science.gov (United States)

    Talalay, Pavel; Markov, Alexey; Sysoev, Mikhail

    2014-05-01

    Antarctic subglacial aquatic environment have become of great interest to the science community because they may provide unique information about microbial evolution, the past climate of the Earth, and the formation of the Antarctic ice sheet. Nowadays it is generally recognized that a vast network of lakes, rivers, and streams exists thousands of meters beneath Antarctic Ice Sheets. Up to date only four boreholes accessed subglacial aquatic system but three of them were filled with high-toxic drilling fluid, and the subglacial water was contaminated. Two recent exploration programs proposed by UK and USA science communities anticipated direct access down to the lakes Ellsworth and Whillans, respectively, in the 2012/2013 Antarctic season. A team of British scientists and engineers engaged in the first attempt to drill into Lake Ellsworth but failed. US research team has successfully drilled through 800 m of Antarctic ice to reach a subglacial lake Whillans and retrieve water and sediment samples. Both activities used hot-water drilling technology to access lakes. Hot water is considered by the world science community as the most clean drilling fluid medium from the present point of view but it cannot solve environmental problems in total because hot-water even when heated to 90 °C, filtered to 0.2 μm, and UV treated at the surface could pick up microorganisms from near-surface snow and circulate them in great volume through the borehole. Another negative impact of hot-water circulation medium is thermal pollution of subglacial water. The new approach to Antarctic subglacial lakes exploration is presented by sampling technology with recoverable autonomous sonde which is equipped by two hot-points with heating elements located on the bottom and top sides of the sonde. All down-hole sonde components will be sterilized by combination of chemical wash, HPV and UV sterilization prior using. At the beginning of the summer season sonde is installed on the surface of the

  8. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Español Eye Health / Eye Health A-Z Dry Eye Sections What Is Dry Eye? Causes of Dry ... Eye Diagnosis Dry Eye Treatment What Is Dry Eye? Written by: Kierstan Boyd Reviewed by: Devin A ...

  9. Social Networks in Silicon Valley

    Institute of Scientific and Technical Information of China (English)

    Joseph Leu

    2006-01-01

    @@ Social network is a dominant, distinguishing characteristic of Silicon Valley. Because innovation entails coping with a high degree of uncertainty,such innovation is particularly dependent on networks.

  10. Session: Long Valley Exploratory Well

    Energy Technology Data Exchange (ETDEWEB)

    Tennyson, George P. Jr.; Finger, John T.; Eichelberger, John C.; Hickox, Charles E.

    1992-01-01

    This session at the Geothermal Energy Program Review X: Geothermal Energy and the Utility Market consisted of four presentations: ''Long Valley Exploratory Well - Summary'' by George P. Tennyson, Jr.; ''The Long Valley Well - Phase II Operations'' by John T. Finger; ''Geologic results from the Long Valley Exploratory Well'' by John C. Eichelberger; and ''A Model for Large-Scale Thermal Convection in the Long Valley Geothermal Region'' by Charles E. Hickox.

  11. Synthetic River Valleys

    Science.gov (United States)

    Brown, R.; Pasternack, G. B.

    2011-12-01

    The description of fluvial form has evolved from anecdotal descriptions to artistic renderings to 2D plots of cross section or longitudinal profiles and more recently 3D digital models. Synthetic river valleys, artificial 3D topographic models of river topography, have a plethora of potential applications in fluvial geomorphology, and the earth sciences in general, as well as in computer science and ecology. Synthetic river channels have existed implicitly since approximately the 1970s and can be simulated from a variety of approaches spanning the artistic and numerical. An objective method of synthesizing 3D stream topography based on reach scale attributes would be valuable for sizing 3D flumes in the physical and numerical realms, as initial input topography for morphodynamic models, stream restoration design, historical reconstruction, and mechanistic testing of interactions of channel geometric elements. Quite simply - simulation of synthetic channel geometry of prescribed conditions can allow systematic evaluation of the dominant relationships between river flow and geometry. A new model, the control curve method, is presented that uses hierarchically scaled parametric curves in over-lapping 2D planes to create synthetic river valleys. The approach is able to simulate 3D stream geometry from paired 2D descriptions and can allow experimental insight into form-process relationships in addition to visualizing past measurements of channel form that are limited to two dimension descriptions. Results are presented that illustrate the models ability to simulate fluvial topography representative of real world rivers as well as how channel geometric elements can be adjusted. The testing of synthetic river valleys would open up a wealth of knowledge as to why some 3D attributes of river channels are more prevalent than others as well as bridging the gap between the 2D descriptions that have dominated fluvial geomorphology the past century and modern, more complete, 3D

  12. Distribution of glacial deposits, soils, and permafrost in Taylor Valley, Antarctica

    Science.gov (United States)

    Bockheim, J.G.; Prentice, M.L.; McLeod, M.

    2008-01-01

    We provide a map of lower and central Taylor Valley, Antarctica, that shows deposits from Taylor Glacier, local alpine glaciers, and grounded ice in the Ross Embayment. From our electronic database, which includes 153 sites from the coast 50 km upvalley to Pearse Valley, we show the distribution of permafrost type and soil subgroups according to Soil Taxonomy. Soils in eastern Taylor Valley are of late Pleistocene age, cryoturbated due to the presence of ground ice or ice-cemented permafrost within 70 cm of the surface, and classified as Glacic and Typic Haploturbels. In central Taylor Valley, soils are dominantly Typic Anhyorthels of mid-Pleistocene age that have dry-frozen permafrost within the upper 70 cm. Salt-enriched soils (Salic Anhyorthels and Petrosalic Anhyorthels) are of limited extent in Taylor Valley and occur primarily on drifts of early Pleistocene and Pliocene age. Soils are less developed in Taylor Valley than in nearby Wright Valley, because of lesser salt input from atmospheric deposition and salt weathering. Ice-cemented permafrost is ubiquitous on Ross Sea, pre-Ross Sea, and Bonney drifts that occur within 28 km of the McMurdo coast. In contrast, dry-frozen permafrost is prevalent on older (???115 ky) surfaces to the west. ?? 2008 Regents of the University of Colorado.

  13. Silicon Valley Lifestyle

    Institute of Scientific and Technical Information of China (English)

    Joseph Leu

    2005-01-01

    @@ As we embrace the rapid developments of the new media age,competitiveness in the field of internet and computer technology is an increasingly crucial factor in stimulating new business,jobs and new industry in the region.Accelerating advancements in new media,internet,software and computer technologies offer new commercial opportunities and sources of economic revenue. Silicon Valley has been a model of the new age since its existence.While the dream place not only has a unique business model,but also has a very special lifestyle.

  14. 77 FR 5403 - Conservation of Antarctic Animals and Plants

    Science.gov (United States)

    2012-02-03

    ... From the Federal Register Online via the Government Publishing Office NATIONAL SCIENCE FOUNDATION 45 CFR Part 670 Conservation of Antarctic Animals and Plants AGENCY: National Science Foundation. ACTION: Final rule. SUMMARY: Pursuant to the Antarctic Conservation Act of 1978, The National...

  15. Biological studies in the Antarctic waters: A review

    Digital Repository Service at National Institute of Oceanography (India)

    Dhargalkar, V.K.

    stream_size 12 stream_content_type text/plain stream_name Proc_Workshop_Antarct_Stud_1990_407.pdf.txt stream_source_info Proc_Workshop_Antarct_Stud_1990_407.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset=ISO...

  16. Laboratory study of nitrate photolysis in Antarctic snow

    DEFF Research Database (Denmark)

    Berhanu, Tesfaye A.; Meusinger, Carl; Erbland, Joseph;

    2014-01-01

    Atmospheric nitrate is preserved in Antarctic snow firn and ice. However, at low snow accumulation sites, post-depositional processes induced by sunlight obscure its interpretation. The goal of these studies (see also Paper I by Meusinger et al. [" Laboratory study of nitrate photolysis in Antarc...... reproduce the stable isotopic composition of nitrate found in Antarctic snow profiles. © 2014 Author(s)....

  17. How much snow falls on the Antarctic ice sheet?

    Directory of Open Access Journals (Sweden)

    C. Palerme

    2014-02-01

    Full Text Available Climate models predict Antarctic precipitation to increase during the 21st century, but their present day Antarctic precipitation differs. A fully model-independent climatology of the Antarctic precipitation characteristics, such as snowfall rates and frequency, is needed to assess the models, but was not available so far. Satellite observation of precipitation by active spaceborne sensors has been possible in the polar regions since the launch of CloudSat in 2006. Here we use CloudSat products to build the first multi-year model-independent climatology of Antarctic precipitation. The mean snowfall rate from August 2006 to April 2011 is 171 mm yr−1 over the Antarctic ice sheet north of 82° S. The ECMWF ERA Interim dataset agrees well with the new satellite climatology.

  18. Emerging spatial patterns in Antarctic prokaryotes

    Directory of Open Access Journals (Sweden)

    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

  19. Fast recession of a West Antarctic glacier

    OpenAIRE

    Rignot, EJ

    1998-01-01

    Satellite radar interferometry observations of Pine Island Glacier, West Antarctica, reveal that the glacier hinge-line position retreated 1.2 ± 0.3 kilometers per year between 1992 and 1996, which in turn implies that the ice thinned by 3.5 ± 0.9 meters per year. The fast recession of Pine Island Glacier, predicted to be a possible trigger for the disintegration of the West Antarctic Ice Sheet, is attributed to enhanced basal melting of the glacier floating tongue by warm ocean waters.

  20. Automatic focusing system of BSST in Antarctic

    Science.gov (United States)

    Tang, Peng-Yi; Liu, Jia-Jing; Zhang, Guang-yu; Wang, Jian

    2015-10-01

    Automatic focusing (AF) technology plays an important role in modern astronomical telescopes. Based on the focusing requirement of BSST (Bright Star Survey Telescope) in Antarctic, an AF system is set up. In this design, functions in OpenCV is used to find stars, the algorithm of area, HFD or FWHM are used to degree the focus metric by choosing. Curve fitting method is used to find focus position as the method of camera moving. All these design are suitable for unattended small telescope.

  1. Longitudinal surface structures (flowstripes on Antarctic glaciers

    Directory of Open Access Journals (Sweden)

    N. F. Glasser

    2011-11-01

    Full Text Available Longitudinal surface structures (''flowstripes'' are common on many glaciers but their origin and significance are poorly understood. In this paper we present observations of the development of these longitudinal structures from four different Antarctic glacier systems (the Lambert Glacier/Amery Ice Shelf area, outlet glaciers in the Ross Sea sector, ice-shelf tributary glaciers on the Antarctic Peninsula, and the onset zone of a tributary to the Recovery Glacier Ice Stream in the Filchner Ice Shelf area. Mapping from optical satellite images demonstrates that longitudinal surface structures develop in two main situations: (1 as relatively wide flow stripes within glacier flow units and (2 as relatively narrow flow stripes where there is convergent flow around nunataks or at glacier confluence zones. Our observations indicate that the confluence features are narrower, sharper, and more clearly defined features. They are characterised by linear troughs or depressions on the ice surface and are much more common than the former type. Longitudinal surface structures within glacier flow units have previously been explained as the surface expression of localised bed perturbations but a universal explanation for those forming at glacier confluences is lacking. Here we propose that these features are formed at zones of ice acceleration and extensional flow at glacier confluences. We provide a schematic model for the development of longitudinal surface structures based on extensional flow that can explain their ridge and trough morphology as well as their down-ice persistence.

  2. Interhemispheric coupling and warm Antarctic interglacials

    Directory of Open Access Journals (Sweden)

    P. B. Holden

    2009-12-01

    Full Text Available Ice core evidence indicates that even though atmospheric CO2 concentrations did not exceed ~300 ppm at any point during the last 800 000 years, East Antarctica was at least ~3–4 °C warmer than pre-industrial (CO2 ~280 ppm in each of the last four interglacials. During the previous three interglacials, this anomalous warming was short lived (~3 000 years and apparently occurred before the completion of Northern Hemisphere deglaciation. Hereafter, we refer to these periods as "Warmer than Present Transients" (WPTs. We here present transient 800 kyr simulations using the intermediate complexity model GENIE-1 which suggest that WPTs could be explained as a consequence of the meltwater-forced slowdown of the Atlantic Meridional Overturning Circulation (AMOC during glacial terminations. It is well known that a slowed AMOC would increase southern Sea Surface Temperature (SST through the bipolar seesaw. Observational data supports this hypothesis, suggesting that the AMOC remained weak throughout the terminations preceding WPTs, strengthening rapidly at a time which coincides closely with peak Antarctic temperature. In order to investigate model and boundary condition uncertainty, we additionally present three ensembles of transient GENIE-1 simulations across Termination II (135 000 to 124 000 BP and three snapshot HadCM3 simulations at 130 000 Before Present (BP. These simulations together reproduce both the timing and magnitude of WPTs, and point to the potential importance of an albedo feedback associated with West Antarctic Ice Sheet (WAIS retreat.

  3. Solar power for an Antarctic rover

    Science.gov (United States)

    Lever, J. H.; Ray, L. R.; Streeter, A.; Price, A.

    2006-03-01

    Sensors mounted on mobile robots could serve a variety of science missions in Antarctica. Although weather conditions can be harsh, Antarctic snowfields offer unique conditions to facilitate long-distance robot deployment: the absence of obstacles, firm snow with high albedo, and 24 h sunlight during the summer. We have developed a four-wheel-drive, solar-powered rover that capitalizes on these advantages. Analyses and field measurements confirm that solar power reflected from Antarctic snow contributes 30-40% of the power available to a robot consisting of a five-side box of solar panels. Mobility analyses indicate that the 80 kg rover can move at 0.8 m s-1 during clear sky conditions on firm snow into a 5 m s-1 headwind, twice the speed needed to achieve the design target of 500 km in 2 weeks. Local winter tests of the chassis demonstrated good grade-climbing ability and lower than predicted rolling resistance. Tests of the completed robot occurred in Greenland in 2005.

  4. Extremophiles in an Antarctic Marine Ecosystem

    Directory of Open Access Journals (Sweden)

    Iain Dickinson

    2016-01-01

    Full Text Available Recent attempts to explore marine microbial diversity and the global marine microbiome have indicated a large proportion of previously unknown diversity. However, sequencing alone does not tell the whole story, as it relies heavily upon information that is already contained within sequence databases. In addition, microorganisms have been shown to present small-to-large scale biogeographical patterns worldwide, potentially making regional combinations of selection pressures unique. Here, we focus on the extremophile community in the boundary region located between the Polar Front and the Southern Antarctic Circumpolar Current in the Southern Ocean, to explore the potential of metagenomic approaches as a tool for bioprospecting in the search for novel functional activity based on targeted sampling efforts. We assessed the microbial composition and diversity from a region north of the current limit for winter sea ice, north of the Southern Antarctic Circumpolar Front (SACCF but south of the Polar Front. Although, most of the more frequently encountered sequences  were derived from common marine microorganisms, within these dominant groups, we found a proportion of genes related to secondary metabolism of potential interest in bioprospecting. Extremophiles were rare by comparison but belonged to a range of genera. Hence, they represented interesting targets from which to identify rare or novel functions. Ultimately, future shifts in environmental conditions favoring more cosmopolitan groups could have an unpredictable effect on microbial diversity and function in the Southern Ocean, perhaps excluding the rarer extremophiles.

  5. CHAMP Magnetic Anomalies of the Antarctic Crust

    Science.gov (United States)

    Kim, Hyung Rae; Gaya-Pique, Luis R.; vonFrese, Ralph R. B.; Taylor, Patrick T.; Kim, Jeong Woo

    2003-01-01

    Regional magnetic signals of the crust are strongly masked by the core field and its secular variations components and hence difficult to isolate in the satellite measurements. In particular, the un-modeled effects of the strong auroral external fields and the complicated- behavior of the core field near the geomagnetic poles conspire to greatly reduce the crustal magnetic signal-to-noise ratio in the polar regions relative to the rest of the Earth. We can, however, use spectral correlation theory to filter the static lithospheric and core field components from the dynamic external field effects. To help isolate regional lithospheric from core field components, the correlations between CHAMP magnetic anomalies and the pseudo magnetic effects inferred from gravity-derived crustal thickness variations can also be exploited.. Employing these procedures, we processed the CHAMP magnetic observations for an improved magnetic anomaly map of the Antarctic crust. Relative to the much higher altitude Orsted and noisier Magsat observations, the CHAMP magnetic anomalies at 400 km altitude reveal new details on the effects of intracrustal magnetic features and crustal thickness variations of the Antarctic.

  6. Antarctic Porifera database from the Spanish benthic expeditions

    OpenAIRE

    Pilar Rios; Javier Cristobo

    2014-01-01

    The information about the sponges in this dataset is derived from the samples collected during five Spanish Antarctic expeditions: Bentart 94, Bentart 95, Gebrap 96, Ciemar 99/00 and Bentart 2003. Samples were collected in the Antarctic Peninsula and Bellingshausen Sea at depths ranging from 4 to 2044 m using va­rious sampling gears.The Antarctic Porifera database from the Spanish benthic expeditions is unique as it provides in­formation for an under-explored region of the Southern Oc...

  7. 27 CFR 9.58 - Carmel Valley.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Carmel Valley. 9.58... Carmel Valley. (a) Name. The name of the viticultural area described in this section is “Carmel Valley.” (b) Approved maps. The approved maps for determining the boundary of the Carmel Valley...

  8. Evolution of collapse valleys in karst - examples from the Carpatho-Balkanides of Serbia

    Science.gov (United States)

    Petrović, Aleksandar S.; Ćalić, Jelena; Spalević, Aleksandra; Pantić, Marko

    2016-04-01

    Development of valleys in karst is an issue which has not been sufficiently studied in karst surface morphology. THESE valleys are long linear forms whose orthogonal projections resemble normal valleys, but most of their characteristics are strongly influenced by karst process. In largest number of relevant references, this subject is either only briefly mentioned or completely lacking. This paper presents the examples of a particular type of valley in karst formed by cave ceiling collapse close to the topographical surface. Karst of the Carpatho-Balkanides in eastern Serbia is characterized by uneven spatial distribution in several large massifs, but also in a large number of relatively small outcrops (patches and belts), which enable the development of contact karst and fluviokarst. Many morphological elements are of fluvial origin, subsequently modified by karst process. Collapse valleys occur mostly at the downstream contacts (where a seasonal watercourse leaves limestones) or in karst/limestone belts. In the first phase, which is visible on the example of the Radovanska Reka, the river course sinks to the swallets in the riverbed and forms a blind valley. After sinking, the water flows through the tunnel cave, while largest part of the valley remains above the cave. The bottom of the dry valley is dissected by deep dolines, reaching almost to the cave roof. In this part of the study, the area was scanned by a multistation Leica Nova MS 50 (resolution 20 cm @ 10 m). In the second phase, the doline bottoms reach the cave ceilings which develop holes at certain points, as it is case at the Zamna River valley. These hollows tend to enlarge with time, and the surface of the cave ceiling is reduced. The third, final phase is characterised by collapse of larger segments of cave ceilings. Only the natural bridges remain, as the remnants of former caves (e.g. in the Vratna River valley, Ravna Reka valley). These parts of valleys in karst are usually narrow, steep

  9. Different adaptations of Chinese winter-over expeditioners during prolonged Antarctic and sub-Antarctic residence

    Science.gov (United States)

    Chen, Nan; Wu, Quan; Li, Hao; Zhang, Tao; Xu, Chengli

    2016-05-01

    Prolonged residence in Antarctica is characterized by exposure to isolated, confined, and extreme (ICE) environment. Winter-over expeditioners at research stations often exhibit a complex of psychophysiological symptoms, which varied by stations and sociocultural backgrounds. To understand the different patterns of psychophysiological responses provoked by environmental stress, we conducted a longitudinal assessment of mood and endocrine function in two groups of Chinese expeditioners who were deployed to sub-Antarctic (Great Wall Station, 62°S, N = 12) and Antarctic (Zhongshan Station, 66°S, N = 16) from December 2003 to 2005. Measures of mood, thyroid function, the levels of plasma catecholamine, and circulating interleukins were obtained at departure from China, mid-winter (Antarctica), end of winter (Antarctica), and return to China, respectively. The Zhongshan Station crew experienced significant increases in fatigue, anger, tension, confusion, and decrease in free thyroxine (FT4), norepinephrine (NE), and epinephrine (E) during the winter, increase in thyrotropin (TSH) and total triiodothyronine (TT3) when returning, whereas their counterparts at Great Wall Station only experienced increased TT3 after deployment. Moreover, compared with the Great Wall Station crew, the Zhongshan Station crew exhibited greater increase in anger, greater decrease in FT4, total thyroxine (TT4), NE and E over the winter, and greater increase in TSH when returning. Chinese expeditioners who lived and worked at the Antarctic station and the sub-Antarctic station for over a year showed different change patterns in mood and endocrine hormones. Negative mood and endocrine dysfunction were positively associated with the severity of environment. The study is a supplement to scientific knowledge on psychophysiological variation under ICE environment, which has certain applied value for the development of preventive countermeasures or interventions.

  10. Dry mouth during cancer treatment

    Science.gov (United States)

    Chemotherapy - dry mouth; Radiation therapy - dry mouth; Transplant - dry mouth; Transplantation - dry mouth ... Some cancer treatments and medicines can cause dry mouth. Symptoms you may have include: Mouth sores Thick ...

  11. Accelerating optimization by tracing valley

    Science.gov (United States)

    Li, Qing-Xiao; He, Rong-Qiang; Lu, Zhong-Yi

    2016-06-01

    We propose an algorithm to accelerate optimization when an objective function locally resembles a long narrow valley. In such a case, a conventional optimization algorithm usually wanders with too many tiny steps in the valley. The new algorithm approximates the valley bottom locally by a parabola that is obtained by fitting a set of successive points generated recently by a conventional optimization method. Then large steps are taken along the parabola, accompanied by fine adjustment to trace the valley bottom. The effectiveness of the new algorithm has been demonstrated by accelerating the Newton trust-region minimization method and the Levenberg-Marquardt method on the nonlinear fitting problem in exact diagonalization dynamical mean-field theory and on the classic minimization problem of the Rosenbrock's function. Many times speedup has been achieved for both problems, showing the high efficiency of the new algorithm.

  12. Mississippi River Valley alluvial aquifer

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set represents the extent of the Mississippi River Valley alluvial aquifer in the states of Missouri, Kentucky, Tennessee, Arkansas, Mississippi, and...

  13. The History of Silicon Valley

    Institute of Scientific and Technical Information of China (English)

    Joseph Leu

    2005-01-01

    @@ Just as Manchester was once the center for indus trial progress, the microelectronics industry also has a heartland. Silicon Valley is located in a thirty by ten miles strip between San Francisco and San Jose,California.

  14. Social Networks in Silicon Valley

    Institute of Scientific and Technical Information of China (English)

    Joseph; Leu

    2006-01-01

      Social network is a dominant, distinguishing characteristic of Silicon Valley. Because innovation entails coping with a high degree of uncertainty,such innovation is particularly dependent on networks.……

  15. The Drentsche Aa valley system

    International Nuclear Information System (INIS)

    This thesis is composed of five papers concerned with Late Quaternary geology and geomorphology of the Aa valley system. The correlation and chronostratigraphic position of the layers have been established by radiocarbon dating. (Auth.)

  16. RailroadValleySpringfish_CH

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — These data identify the areas where final critical habitat for the Railroad Valley springfish (Crenichthys nevadae) occur. The irrigation ditch that is on the north...

  17. Summertime wind climate in Yerevan: valley wind systems

    Science.gov (United States)

    Gevorgyan, Artur

    2016-05-01

    1992-2014 wind climatology analysis in Yerevan is presented with particular focus given to the summertime thermally induced valley wind systems. Persistence high winds are observed in Yerevan during July-August months when the study region is strongly affected by a heat-driven plain-plateau circulation. The local valley winds arrive in Yerevan in the evening hours, generally, from 1500 to 1800 UTC, leading to rapid enhancement of wind speeds and dramatic changes in wind direction. Valley-winds significantly impact the local climate of Yerevan, which is a densely populated city. These winds moderate evening temperatures after hot and dry weather conditions observed during summertime afternoons. On the other hand, valley winds result in significantly higher nocturnal temperatures and more frequent occurrence of warm nights (tn90p) in Yerevan due to stronger turbulent mixing of boundary layer preventing strong surface cooling and temperature drop in nighttime and morning hours. The applied WRF-ARW limited area model is able to simulate the key features of the observed spatial pattern of surface winds in Armenia associated with significant terrain channeling, wind curls, etc. By contrast, ECMWF EPS global model fails to capture mesoscale and local wind systems over Armenia. However, the results of statistical verification of surface winds in Yerevan showed that substantial biases are present in WRF 18-h wind forecasts, as well as, the temporal variability of observed surface winds is not reproduced adequately in WRF-ARW model.

  18. VEGETATION INVENTORY OF BALABANDERE VALLEY

    OpenAIRE

    Erol, Ulvi Erhan

    2009-01-01

    Balabandere Valley where Belgrad forest and Bosphorus meet in the easterly orientation of the forest has a very important ecological wealth within the greater Istanbul manucipality. The area, in which this study was conducted, has a potantial to become an outdoor recreation laboratory in and around Istanbul city. Balabandere valley and its vicinity can as well be described as a conservation zone with its cultural and ecological landscaoe history. It harbors a very crucial watershed for the ci...

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

    Directory of Open Access Journals (Sweden)

    Jerzy Fabiszewski

    2014-02-01

    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.

  20. Resistance of Antarctic black fungi and cryptoendolithic communities to simulated space and Martian conditions.

    Science.gov (United States)

    Onofri, S; Barreca, D; Selbmann, L; Isola, D; Rabbow, E; Horneck, G; de Vera, J P P; Hatton, J; Zucconi, L

    2008-01-01

    Dried colonies of the Antarctic rock-inhabiting meristematic fungi Cryomyces antarcticus CCFEE 515, CCFEE 534 and C. minteri CCFEE 5187, as well as fragments of rocks colonized by the Antarctic cryptoendolithic community, were exposed to a set of ground-based experiment verification tests (EVTs) at the German Aerospace Center (DLR, Köln, Germany). These were carried out to test the tolerance of these organisms in view of their possible exposure to space conditions outside of the International Space Station (ISS). Tests included single or combined simulated space and Martian conditions. Responses were analysed both by cultural and microscopic methods. Thereby, colony formation capacities were measured and the cellular viability was assessed using live/dead dyes FUN 1 and SYTOX Green. The results clearly suggest a general good resistance of all the samples investigated. C. minteri CCFEE 5187, C. antarcticus CCFEE 515 and colonized rocks were selected as suitable candidates to withstand space flight and long-term permanence in space on the ISS in the framework of the LIchens and Fungi Experiments (LIFE programme, European Space Agency). PMID:19287532

  1. Changes in the West Antarctic ice sheet

    International Nuclear Information System (INIS)

    The portion of the West Antarctic ice sheet that flows into the Ross Sea is thinning in some places and thickening in others. These changes are not caused by any current climatic change, but by the combination of a delayed response to the end of the last global glacial cycle and an internal instability. The near-future impact of the ice sheet on global sea level is largely due to processes internal to the movement of the ice sheet, and not so much to the threat of a possible greenhouse warming. Thus the near-term future of the ice sheet is already determined. However, too little of the ice sheet has been surveyed to predict its overall future behavior

  2. Joint Antarctic School Expedition - An International Collaboration for High School Students and Teachers on Antarctic Science

    Science.gov (United States)

    Botella, J.; Warburton, J.; Bartholow, S.; Reed, L. F.

    2014-12-01

    The Joint Antarctic School Expedition (JASE) is an international collaboration program between high school students and teachers from the United States and Chile aimed at providing the skills required for establishing the scientific international collaborations that our globalized world demands, and to develop a new approach for science education. The National Antarctic Programs of Chile and the United States worked together on a pilot program that brought high school students and teachers from both countries to Punta Arenas, Chile, in February 2014. The goals of this project included strengthening the partnership between the two countries, and building relationships between future generations of scientists, while developing the students' awareness of global scientific issues and expanding their knowledge and interest in Antarctica and polar science. A big component of the project involved the sharing by students of the acquired knowledge and experiences with the general public. JASE is based on the successful Chilean Antarctic Science Fair developed by Chile´s Antarctic Research Institute. For 10 years, small groups of Chilean students, each mentored by a teacher, perform experimental or bibliographical Antarctic research. Winning teams are awarded an expedition to the Chilean research station on King George Island. In 2014, the Chileans invited US participation in this program in order to strengthen science ties for upcoming generations. On King George Island, students have hands-on experiences conducting experiments and learning about field research. While the total number of students directly involved in the program is relatively small, the sharing of the experience by students with the general public is a novel approach to science education. Research experiences for students, like JASE, are important as they influence new direction for students in science learning, science interest, and help increase science knowledge. We will share experiences with the

  3. Organic carbon in Antarctic snow: spatial trends and possible sources

    Digital Repository Service at National Institute of Oceanography (India)

    Antony, R.; Mahalinganathan, K.; Thamban, M.; Nair, S.

    Organic carbon records in Antarctic snow are sparse despite the fact that it is of great significance to global carbon dynamics, snow photochemistry, and air–snow exchange processes. Here, surface snow total organic carbon (TOC) along with sea...

  4. A Comparative Study of Antarctic Arctic and Himalayan Ice

    Directory of Open Access Journals (Sweden)

    R. C. Pathak

    1989-07-01

    Full Text Available Arctic, Antarctic and inaccessible lofty regions of Himalayas,which are geographically diverse areas and have been a constant source of inspiration, envisages a challenging field of study 'by early adventurers and scientists of the world. Characteristics of ice obtained at Arctic and Antarctic do not possess similar properties. Even thesalient properties of snow and ice of western and central Himalayas vary due to its differing free water content. A study has been carriedout based on recent Antarctic Expedition by Indian scientists and the data gathered along litha-tectonic regions of Himalayas and their characteristics have been compared, wkich brings out stratigraphic and metamorphic characteristics of the ice and snow. In the present paper,an analysis of the ice and snow properties of Arctic, Antarctic and Himalayan regions has been presented.

  5. Climate Prediction Center (CPC) Daily Antarctic Oscillation Index

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Antarctic Oscillation (AAO) is a leading teleconnection pattern in the Southern Hemisphere circulation. It is calculated as the first Empirical Orthogonal...

  6. Field experiment on impacts of grass belt length on characteristics of sediment yields and transport rates for gullies in Jinsha dry-hot valley region%沟床草被对干热河谷冲沟产沙特性影响的野外模拟试验

    Institute of Scientific and Technical Information of China (English)

    杨丹; 熊东红; 张宝军; 郭敏; 郑学用; 张素

    2015-01-01

    金沙江干热河谷冲沟极为发育,水土流失强烈,严重威胁着该区的生态安全和社会经济发展。为探明植被影响径流过程、促进沟床稳定的机理,该研究采用野外放水冲刷试验,研究分析了沟床草被带长度对径流产输沙过程和特征的影响,旨在探明沟床草被影响下径流含沙量和输沙率时空变化规律。结果表明:1)增大草被带长度可有效降低冲沟径流泥沙含量,改变径流泥沙含量的时空分布特征。泥沙含量在时间上呈指数递减趋势,在冲沟径流运动方向上呈增大趋势。沟床草被带越长,泥沙含量在时间上波动性越弱,递减趋势越明显;随沟床草被带长度的增大,径流泥沙含量在沟床径流运动方向上的增大趋势有减缓现象;此外,当草被带长度增加到8 m以后,进一步增加草被带长度对减小径流泥沙含量效果不显著,而对照小区和4 m草被带小区泥沙含量均显著高于草被带长度≥8 m的小区,说明8 m草被带是降低径流泥沙含量的较好配置长度;2)沟床草被带对径流输沙率有减小作用。当草被带长度<8 m时,径流输沙率高于草被带>8 m的小区,且在时间上呈先增大后急剧减小而后趋于稳定的变化趋势。当草被带长度≥8 m时,径流输沙率在时间上表现出微弱的降低趋势。试验冲沟径流输沙率均值在空间上沿径流运动方向自冲沟上游至其下游表现出增大趋势,但草被带长度对输沙率在冲沟径流运动方向上的增大过程有较大影响。该研究为植被措施控制冲沟侵蚀提供理论依据。%Permanent gully is well developed in Jinsha Dry-hot valley region in China. The ravine density of this region can be up to 7.4 km/km2 with the maximum soil erosion modulus 1.64×104 t/(km2·a). Gully erosion seriously threatens the ecological security and social-economic development of the region. Vegetation

  7. Fundamental differences between Arctic and Antarctic ozone depletion

    OpenAIRE

    Solomon, Susan; Haskins, Jessica; Ivy, Diane J.; Min, Flora

    2014-01-01

    Fundamental differences in observed ozone depletion between the Arctic and the Antarctic are shown, clarifying distinctions between both average and extreme ozone decreases in the two hemispheres. Balloon-borne and satellite measurements in the heart of the ozone layer near 18−24 km altitude show that extreme ozone decreases often observed in the Antarctic ozone hole region have not yet been measured in the Arctic in any year, including the unusually cold Arctic spring of 2011. The data provi...

  8. Perspectives on the economic history of the Antarctic region

    OpenAIRE

    Basberg, Bjørn L.

    2005-01-01

    This paper starts out by indicating how the economic history of the Antarctic could be conceptualized, given the peculiarities of the continent and the region (no permanent population, no sovereignty in a traditional sense, extreme remoteness, rigorous climate etc.). Second, it describes the main industries throughout Antarctic history. Third, it examines the quantitative data available on economic activity in the region, suggests how we should proceed to analyse the economic a...

  9. Holocene subsurface temperature variability in the eastern Antarctic continental margin

    OpenAIRE

    Kim, J. H.; X. Crosta; Willmott, V.; Renssen, H.; J. Bonnin; Helmke, P.; Schouten, S.; Sinninghe Damsté, J.S.

    2012-01-01

    We reconstructed subsurface (similar to 45-200 m water depth) temperature variability in the eastern Antarctic continental margin during the late Holocene, using an archaeal lipid-based temperature proxy (TEX86 L). Our results reveal that subsurface temperature changes were probably positively coupled to the variability of warmer, nutrient-rich Modified Circumpolar Deep Water (MCDW, deep water of the Antarctic circumpolar current) intrusion onto the continental shelf. The TEX86 L record, in c...

  10. Wind profile radar for study of Antarctic air circulation

    International Nuclear Information System (INIS)

    After a brief discussion of meteorological methods used in the Antarctic, the paper gives an outline of a coordinated international research project whose objective is to set up a wind profiler radar station that would give meteorologists information regarding Antarctic atmospheric dynamics useful in their investigation of the causes and effects of the hole in the ozone layer. The radar instrumentation is to provide continuous readings of wind velocity at varying altitudes above the polar continent

  11. Obliquity-paced Pliocene West Antarctic ice sheet oscillations

    OpenAIRE

    Naish, T.; Antarctic Research Centre, Victoria University of Wellington, Kelburn Parade, PO Box 600, Wellington 6012, New Zealand; Powell, R.; Department of Geology & Environmental Geosciences, Northern Illinois University, DeKalb, Illinois 60115, USA.; Levy, R.; ANDRILL Science Management Office, University of Nebraska-Lincoln, Lincoln, USA; Wilson, G.; University of Otago, Department of Geology, PO Box 56, Leith Street, Dunedin, Otago 9001, New Zealand; Scherer, R.; Department of Geology & Environmental Geosciences, Northern Illinois University, DeKalb, Illinois 60115, USA.; Talarico, F.; Universita` di Siena, Dipartimento di Scienze delle Terra, Via Laterina 8, I-53100 Siena, Italy; Krissek, L.; Ohio State University, Department of Geological Sciences, 275 Mendenhall Lab, 125 South Oval Mall, Columbus, Ohio 43210, USA; Niessen, F.; Alfred Wegener Institute, Department of Geosciences, Postfach 12 01 6, Am Alten Hafen 26, D-27515 Bremerhaven, Germany; Pompilio, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia; Wilson, T.; Ohio State University, Department of Geological Sciences, 275 Mendenhall Lab, 125 South Oval Mall, Columbus, Ohio 43210, USA; Carter, L.; Antarctic Research Centre, Victoria University of Wellington, Kelburn Parade, PO Box 600, Wellington 6012, New Zealand; DeConto, R.; Department of Geosciences, 233 Morrell Science Centre, University of Massachusetts, Amherst, Massachusetts 01003-9297, USA; Huybers, P.; Department of Earth and Planetary Sciences, Harvard University, Massachusetts 02138, USA; McKay, R.; Antarctic Research Centre, Victoria University of Wellington, PO Box 600, Wellington - New Zealand; Pollard, D.; Earth and Environmental Systems Institute, 2217 Earth-Engineering Science Bldg, University Park, PA 16802, USA

    2009-01-01

    Thirty years after oxygen isotope records frommicrofossils deposited in ocean sediments confirmed the hypothesis that variations in the Earth’s orbital geometry control the ice ages1, fundamental questions remain over the response of the Antarctic ice sheets to orbital cycles2. Furthermore, an understanding of the behaviour of the marine-based West Antarctic ice sheet (WAIS) during the ‘warmer-than- present’ early-Pliocene epoch (̃5–3Myr ago) is needed to better constrain the possibl...

  12. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Uveitis Focus On Pediatric Ophthalmology Education Center Oculofacial Plastic Surgery Center Laser Surgery Education Center Redmond Ethics Center Global Ophthalmology ... Eye Risk Dry Eye Diagnosis Dry Eye Treatment What Is ...

  13. A Bivalve Proxy for Neogene Antarctic Shelf Marine Environments

    Science.gov (United States)

    Clark, N. A.; Williams, M.; Quilty, P. G.; Leng, M. J.; Zalasiewicz, J. A.; Smellie, J.; Dowsett, H. J.

    2012-12-01

    The Neogene shallow-marine successions of the Antarctic Peninsula and of the East Antarctic region preserve rich assemblages of bivalve molluscs. These bivalve molluscs provide a detailed record of palaeoseasonality in the chemical signature and morphology of their shells that can be used to assess sea temperatures and sea ice extent for the Antarctic shelf during the Pliocene. Analyses identify the following. 1) Neogene bivalves from James Ross Island, Antarctic Peninsula, comprise material of late Miocene through to late Pliocene age. Results identify warm (ca. 3-10 °C) early Pliocene sea temperatures, and cooler late Pliocene sea temperatures (ca. 0-4 °C), and flag a cooling trend which is consistent with the evolution of polar climate through this interval. 2) Neogene bivalves from the Larsemann Hills, East Antarctic, identify generally warmer than present sea temperatures (ca. 0-11 °C) in the early Pliocene consistent with data from other fossil groups of this age, including dolphins and silicoflagellates. The new data may provide significant ground truth for climate models assessing the Southern Ocean and Antarctic shelf climate.

  14. Transcriptomics and comparative analysis of three antarctic notothenioid fishes.

    Directory of Open Access Journals (Sweden)

    Seung Chul Shin

    Full Text Available For the past 10 to 13 million years, Antarctic notothenioid fish have undergone extraordinary periods of evolution and have adapted to a cold and highly oxygenated Antarctic marine environment. While these species are considered an attractive model with which to study physiology and evolutionary adaptation, they are poorly characterized at the molecular level, and sequence information is lacking. The transcriptomes of the Antarctic fishes Notothenia coriiceps, Chaenocephalus aceratus, and Pleuragramma antarcticum were obtained by 454 FLX Titanium sequencing of a normalized cDNA library. More than 1,900,000 reads were assembled in a total of 71,539 contigs. Overall, 40% of the contigs were annotated based on similarity to known protein or nucleotide sequences, and more than 50% of the predicted transcripts were validated as full-length or putative full-length cDNAs. These three Antarctic fishes shared 663 genes expressed in the brain and 1,557 genes expressed in the liver. In addition, these cold-adapted fish expressed more Ub-conjugated proteins compared to temperate fish; Ub-conjugated proteins are involved in maintaining proteins in their native state in the cold and thermally stable Antarctic environments. Our transcriptome analysis of Antarctic notothenioid fish provides an archive for future studies in molecular mechanisms of fundamental genetic questions, and can be used in evolution studies comparing other fish.

  15. Effect of Antarctic solar radiation on sewage bacteria viability

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, K.A. [National Environment Research Council, Cambridge (United Kingdom). British Antarctic Survey

    2005-06-01

    The majority of coastal Antarctic research stations discard untreated sewage waste into the near-shore marine environment. However, Antarctic solar conditions are unique, with ozone depletion increasing the proportion of potentially damaging ultraviolet-B (UV-B) radiation reaching the marine environment. This study assessed the influence of Antarctic solar radiation on the viability of Escherichia coli and sewage microorganisms at Rothera Research Station, Adelaide Island, Antarctic Peninsula. Cell viability decreased with increased exposure time and with exposure to shorter wavelengths of solar radiation. Cell survival also declined with decreasing cloud cover, solar zenith angle and ozone column depth. However, particulates in sewage increased the persistence of viable bacteria. Ultraviolet radiation doses over Rothera Point were highest during the austral summer. During this time, solar radiation may act to partially reduce the number of viable sewage-derived microorganisms in the surface seawater around Antarctic outfalls. Nevertheless, this effect is not reliable and every effort should be made to fully treat sewage before release into the Antarctic marine environment. (author)

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

    Directory of Open Access Journals (Sweden)

    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.

  17. Irrigation channels of the Upper Rhone valley (Switzerland). Geomorphological analysis of a cultural heritage

    Science.gov (United States)

    Reynard, Emmanuel

    2016-04-01

    The Upper Rhone valley (Canton of Valais, Switzerland) is characterised by dry climatic conditions that explain the presence of an important network (about 800 km) of irrigation channels - called Bisses in the French-speaking part of the canton or Suonen in the German-speaking area - dating back to the Middle Ages. This network constitutes a cultural heritage and during the last 30 years these agricultural infrastructures have sparked a renewed interest for tourist and cultural reasons. Indeed, the paths along the channels are used as tourist trails and several abandoned channels have been renovated for tourist use. Based on an inventory of the Bisses/Suonen of Valais, the proposed communication has three aims: (1) to analyse the geomorphological context (morphometric analysis, structural geomorphology, main processes) of various types of channels and to show the impact of the geomorphological context on the building techniques; (2) to identify particularly active processes along the channels; (3) to classify the Bisses/Suonen according to their geomorphological value and to their geomorphological sensitivity, and to propose managing measures. Structural and climatic conditions influence the geomorphological context of the channels. In a structural point of view, irrigation channels are developed in three main contexts: (1) in the Aar Massif crystalline basement; (2) in the limestone and marl cover nappes of the Helvetic Alps; (3) in the metamorphic cover nappes of the Penninic domain. The Rhone River valley is boarded by two high mountain ranges: the Penninic Alps in the South and the Bernese Alps in the North. Because of rain shadow effects, the climate is relatively dry and, between Brig and Martigny, annual rainfall is not more than 600 mm at 500 m ASL and 800 mm at 1600 m ASL. Nevertheless, due to important vertical precipitation gradients annual rainfall totals are high at high altitudes. On the southern facing tributary valleys, the dry climatic conditions

  18. Screening on DHA-producing Antarctic bacteria N- 6 and its cultural conditions

    Institute of Scientific and Technical Information of China (English)

    Zhang Botao; Miao Jin-lai; Hui Hanxing; Wang Qing

    2006-01-01

    In Antarctic, the geography and climate differs from those in other places,and the bacteria there have adapted well to the environment there. Two hundred strains of bacteria were isolated from the sea ice in Antarctica. The bacteria were screened for DHA by means of GC, with fish oil as the standard. Seven strains containing DHA or EPA were obtained, among which the strain of No. N-6 was outstanding. And the component of DHA was identified by GC-MS. The relative content of DHA in N-6 was 8.72%, and total lipids in dry bacteria was 22.54%. The effects of some factors, including temperature, salinity and pH value, on the growth and DHAcontent of strain N-6 were studied. The results show that the DHA-content is relatively high when in low temperature and high pH, and the bacterium is psychrophilic, alkalophilic.

  19. Development of a regional glycerol dialkyl glycerol tetraether (GDGT)-temperature calibration for Antarctic and sub-Antarctic lakes

    Science.gov (United States)

    Foster, Louise C.; Pearson, Emma J.; Juggins, Steve; Hodgson, Dominic A.; Saunders, Krystyna M.; Verleyen, Elie; Roberts, Stephen J.

    2016-01-01

    A regional network of quantitative reconstructions of past climate variability is required to test climate models. In recent studies, temperature calibration models based on the relative abundances of sedimentary glycerol dialkyl glycerol tetraethers (GDGTs) have enabled past temperature reconstructions in both marine and terrestrial environments. Nevertheless, to date these methods have not been widely applied in high latitude environments due to poor performance of the GDGT-temperature calibrations at lower temperatures. To address this we studied 32 lakes from Antarctica, the sub-Antarctic Islands and Southern Chile to: 1) quantify their GDGT composition and investigate the environmental controls on GDGT composition; and 2) develop a GDGT-temperature calibration model for inferring past temperatures from Antarctic and sub-Antarctic lakes. GDGTs were found in all 32 lakes studied and in 31 lakes branched GDGTs (brGDGTs) were the dominant compounds. Statistical analyses of brGDGT composition in relation to temperature, pH, conductivity and water depth showed that the composition of brGDGTs is strongly correlated with mean summer air temperature (MSAT). This enabled the development of the first regional brGDGT-temperature calibration for use in Antarctic and sub-Antarctic lakes using four brGDGT compounds (GDGT-Ib, GDGT-II, GDGT-III and GDGT-IIIb). A key discovery was that GDGT-IIIb is of particular importance in cold lacustrine environments. The addition of this compound significantly improved the model's performance from r2 = 0.67, RMSEP-LOO (leave-one-out) = 2.23 °C, RMSEP-H (h-block) = 2.37 °C when applying the re-calibrated global GDGT-temperature calibration to our Antarctic dataset to r2 = 0.83, RMSEP-LOO = 1.68 °C, RMSEP-H = 1.65 °C for our new Antarctic calibration. This shows that Antarctic and sub-Antarctic, and possibly other high latitude, palaeotemperature reconstructions should be based on a regional GDGT-temperature calibration where specific

  20. Biological Iron Isotopic Fractionations in Antarctic Endolithic Microbial Communities

    Science.gov (United States)

    Sun, H.; Beard, B. L.; Johnson, C. M.; Nealson, K. H.

    2002-12-01

    In the McMurdo Dry Valleys, cryptoendolithic microorganisms under sandstone surfaces secrete oxalic acid to leach iron oxides from the rock. A translucent surface rock layer is necessary to trsansmit sufficient sunlight to support photosynthetic primary production and long-term survival. Part of the mobilized iron is re-deposited on the rock surface as a protective crust; the rest accumulates below the colonized zone. We report here that this weathering process results in redistribution of the iron isotopes, with the microbial zone being enriched in heavy isotopes relative to the rock crust and the accumulation zone. In a simulated laboratory experiment to understand the cause for this isotopic effect, hematite was incubated in 5 mM oxalic acid under light. Analysis of the initial dissolved iron showed that the dissolution in itself could not reproduce the isotopic shifts observed in the rock. Presumably, equilibrium isotopic fractionation between Fe(II) and Fe(III) species is the cause, as both are produced from oxalate-promoted dissolution of iron oxides. Subsequently, microorganisms would recycle oxalate for carbon nutrient and as a result destroy iron oxalate complexes. Without chelation, the ferric iron, which is isotopically heavier, would precipitate first and the ferrous iron later as they are transported downward through the circumneutral endolithic environment, effectively achieving a physical separation of the different isotopes. On Mars, if endolithic microorganisms had occurred and then became extinct as the planet dried and cooled, their iron isotopic biosignatures might be well preserved because subsequent reworking of iron would be unlikely without liquid water.

  1. Coordinated Analyses of Antarctic Sediments as Mars Analog Materials Using Reflectance Spectroscopy and Current Flight-Like Instruments for CheMin, SAM and MOMA

    Science.gov (United States)

    Bishop, Janice L.; Franz, Heather B.; Goetz, Walter; Blake, David F.; Freissinet, Caroline; Steininger, Harald; Goesmann, Fred; Brinckerhoff, William B.; Getty, Stephanie; Pinnick, Veronica T.; Mahaffy, Paul R.; Dyar, M. Darby

    2013-01-01

    Coordinated analyses of mineralogy and chemistry of sediments from the Antarctic Dry Valleys illustrate how data obtained using flight-ready technology of current NASA and ESA missions can be combined for greater understanding of the samples. Mineralogy was measured by X-ray diffraction (XRD) and visible/ near-infrared (VNIR) reflectance spectroscopy. Chemical analyses utilized a quadrupole mass spectrometer (QMS) to perform pyrolysis-evolved gas analysis (EGA) and gas chromatography-mass spectrometry (GC/MS) both with and without derivatization, as well as laser desorption-mass spectrometry (LD/MS) techniques. These analyses are designed to demonstrate some of the capabilities of near-term landed Mars missions, to provide ground truthing of VNIR reflectance data acquired from orbit by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on MRO and to provide detection limits for surface- operated instruments: the Chemistry and Mineralogy (CheMin) and Sample Analysis at Mars (SAM) instrument suites onboard Mars Science Laboratory (MSL) and the Mars Organic Molecule Analyzer (MOMA) onboard ExoMars-2018. The new data from this study are compared with previous analyses of the sediments performed with other techniques. Tremolite was found in the oxic region samples for the first time using the CheMin-like XRD instrument. The NIR spectral features of tremolite are consistent with those observed in these samples. Although the tremolite bands are weak in spectra of these samples, spectral features near 2.32 and 2.39 micrometers could be detected by CRISM if tremolite is present on the martian surface. Allophane was found to be a good match to weak NIR features at 1.37-1.41, 1.92, and 2.19 micrometers in spectra of the oxic region sediments and is a common component of immature volcanic soils. Biogenic methane was found to be associated with calcite in the oxic region samples by the SAM/EGA instrument and a phosphoric acid derivative was found in the anoxic

  2. Central-north China precipitation as reconstructed from the Qing dynasty: Signal of the Antarctic Atmospheric Oscillation

    Science.gov (United States)

    Wang, Huijun; Fan, Ke

    2005-12-01

    Based on the long-term Central-north China precipitation (CNCP) time series reconstructed from the Qing Dynasty Official Document, the relationship between CNCP and the Antarctic Atmospheric Oscillation (AAO) in June-July is examined. The analysis yields a (significant) negative correlation of -0.22. The signal of AAO in CNCP is further studied through analyses of the atmospheric general circulation variability related to AAO. It follows that AAO-related variability of convergence and convection over the tropical western Pacific can exert impact on the circulation condition and precipitation in north China (actually, the precipitation in the Yangtze River Valley as well) through atmospheric teleconnection known as the East Asia-Pacific (or Pacific-Japan) teleconnection wave pattern. There is also an AAO-connected wave train in the vorticity field at high troposphere over Eurasia, providing an anti-cyclonic circulation in central-north China favorable to the decline of precipitation in positive phase of AAO.

  3. Iron isotope geochemistry in the Antarctic cryptoendolithic microbial ecosystem

    Science.gov (United States)

    Sun, H.

    2002-05-01

    The stable isotope composition of iron is a potentially powerful tracer of biogeochemical cycles because iron is ubiquitous, it is required by all organisms, and it is resistant to alterations during diagenesis. Here we report evidence of biological iron isotope fractionation in the weathering process of sandstone in McMurdo Dry Valleys, Antarctica, caused by the cryptoendolithic lichen-dominated microbial community that live below the rock surface. The fungi secrete oxalic acid, which under the sunlight reduces and dissolves the iron in the colonized zone. The mobilized iron diffuses to the rock surface and the rock interior below the organisms where it is re-oxidized. This leaching process is shown to prefer lighter isotopes of iron, leaving the colonized layer enriched in del 56Fe by as much 0.8 per mil. Had endolithic microorganisms occurred on Mars as commonly believed, they might have left similar iron biosignatures, well preserved in rocks because of the absence of subsequent aqueous activities.

  4. Modelling photochemistry in alpine valleys

    Directory of Open Access Journals (Sweden)

    G. Brulfert

    2005-01-01

    Full Text Available Road traffic is a serious problem in the Chamonix Valley, France: traffic, noise and above all air pollution worry the inhabitants. The big fire in the Mont-Blanc tunnel made it possible, in the framework of the POVA project (POllution in Alpine Valleys, to undertake measurement campaigns with and without heavy-vehicle traffic through the Chamonix and Maurienne valleys, towards Italy (before and after the tunnel re-opening. Modelling is one of the aspects of POVA and should make it possible to explain the processes leading to episodes of atmospheric pollution, both in summer and in winter. Atmospheric prediction model ARPS 4.5.2 (Advanced Regional Prediction System, developed at the CAPS (Center for Analysis and Prediction of Storms of the University of Oklahoma, enables to resolve the dynamics above a complex terrain. This model is coupled to the TAPOM 1.5.2 atmospheric chemistry (Transport and Air POllution Model code developed at the Air and Soil Pollution Laboratory of the Ecole Polytechnique Fédérale de Lausanne. The numerical codes MM5 and CHIMERE are used to compute large scale boundary forcing. This paper focuses on modelling Chamonix valley using 300-m grid cells to calculate the dynamics and the reactive chemistry which makes possible to accurately represent the dynamics in the Chamonix valley (slope and valley winds and to process chemistry at fine scale. The summer 2003 intensive campaign was used to validate the model and to study chemistry. NOy according to O3 reduction demonstrates a VOC controlled regime, different from the NOx controlled regime expected and observed in the nearby city of Grenoble.

  5. Modelling photochemistry in alpine valleys

    Directory of Open Access Journals (Sweden)

    G. Brulfert

    2005-03-01

    Full Text Available Road traffic is a serious problem in the Chamonix Valley, France: traffic, noise and above all air pollution worry the inhabitants. The big fire in the Mont-Blanc tunnel made it possible, in the framework of the POVA project (POllution in Alpine Valleys, to undertake measurement campaigns with and without heavy-vehicle traffic through the valley, towards Italy (before and after the tunnel re-opening. Modelling in POVA should make it possible to explain the processes leading to episodes of atmospheric pollution, both in summer and in winter.

    Atmospheric prediction model ARPS 4.5.2 (Advanced Regional Prediction System, developed at the CAPS (Center for Analysis and Prediction of Storms of the University of Oklahoma, enables to resolve the dynamics above a complex terrain.

    This model is coupled to the TAPOM 1.5.2 atmospheric chemistry (Transport and Air POllution Model code developed at the Air and Soil Pollution Laboratory of the Ecole Polytechnique Fédérale de Lausanne.

    The numerical codes MM5 and CHIMERE are used to compute large scale boundary forcing.

    Using 300-m grid cells to calculate the dynamics and the reactive chemistry makes possible to accurately represent the dynamics in the valley (slope and valley winds and to process chemistry at fine scale.

    Validation of campaign days allows to study chemistry indicators in the valley. NOy according to O3 reduction demonstrates a VOC controlled regime, different from the NOx controlled regime expected and observed in the nearby city of Grenoble.

  6. Antarctic Single Frames = Frame Level Records of Antarctica Photos: 1946 - 2000

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Aerial photographs of Antarctica from the United States Antarctic Resource Center (USARC) and the British Antarctic Survey (BAS) are maintained in this collection....

  7. Valley evolution by meandering rivers

    Science.gov (United States)

    Limaye, Ajay Brian Sanjay

    Fluvial systems form landscapes and sedimentary deposits with a rich hierarchy of structures that extend from grain- to valley scale. Large-scale pattern formation in fluvial systems is commonly attributed to forcing by external factors, including climate change, tectonic uplift, and sea-level change. Yet over geologic timescales, rivers may also develop large-scale erosional and depositional patterns that do not bear on environmental history. This dissertation uses a combination of numerical modeling and topographic analysis to identify and quantify patterns in river valleys that form as a consequence of river meandering alone, under constant external forcing. Chapter 2 identifies a numerical artifact in existing, grid-based models that represent the co-evolution of river channel migration and bank strength over geologic timescales. A new, vector-based technique for bank-material tracking is shown to improve predictions for the evolution of meander belts, floodplains, sedimentary deposits formed by aggrading channels, and bedrock river valleys, particularly when spatial contrasts in bank strength are strong. Chapters 3 and 4 apply this numerical technique to establishing valley topography formed by a vertically incising, meandering river subject to constant external forcing---which should serve as the null hypothesis for valley evolution. In Chapter 3, this scenario is shown to explain a variety of common bedrock river valley types and smaller-scale features within them---including entrenched channels, long-wavelength, arcuate scars in valley walls, and bedrock-cored river terraces. Chapter 4 describes the age and geometric statistics of river terraces formed by meandering with constant external forcing, and compares them to terraces in natural river valleys. The frequency of intrinsic terrace formation by meandering is shown to reflect a characteristic relief-generation timescale, and terrace length is identified as a key criterion for distinguishing these

  8. The safety band of Antarctic ice shelves

    Science.gov (United States)

    Fürst, Johannes Jakob; Durand, Gaël; Gillet-Chaulet, Fabien; Tavard, Laure; Rankl, Melanie; Braun, Matthias; Gagliardini, Olivier

    2016-05-01

    The floating ice shelves along the seaboard of the Antarctic ice sheet restrain the outflow of upstream grounded ice. Removal of these ice shelves, as shown by past ice-shelf recession and break-up, accelerates the outflow, which adds to sea-level rise. A key question in predicting future outflow is to quantify the extent of calving that might precondition other dynamic consequences and lead to loss of ice-shelf restraint. Here we delineate frontal areas that we label as `passive shelf ice’ and that can be removed without major dynamic implications, with contrasting results across the continent. The ice shelves in the Amundsen and Bellingshausen seas have limited or almost no `passive’ portion, which implies that further retreat of current ice-shelf fronts will yield important dynamic consequences. This region is particularly vulnerable as ice shelves have been thinning at high rates for two decades and as upstream grounded ice rests on a backward sloping bed, a precondition to marine ice-sheet instability. In contrast to these ice shelves, Larsen C Ice Shelf, in the Weddell Sea, exhibits a large `passive’ frontal area, suggesting that the imminent calving of a vast tabular iceberg will be unlikely to instantly produce much dynamic change.

  9. Iodine monoxide in the Antarctic snowpack

    Directory of Open Access Journals (Sweden)

    U. Platt

    2009-11-01

    Full Text Available Recent ground-based and space borne observations suggest the presence of significant amounts of iodine monoxide in the boundary layer of Antarctica, which are expected to have an impact on the ozone budget and might contribute to the formation of new airborne particles. So far, the source of these iodine radicals has been unknown. This paper presents long-term measurements of iodine monoxide at the German Antarctic research station Neumayer, which indicate that the snowpack is the main source for iodine radicals. The measurements have been performed using multi-axis differential optical absorption spectroscopy (MAX-DOAS. Using a coupled atmosphere-snowpack radiative transfer model, the comparison of the signals observed from scattered skylight and from light reflected by the snowpack yields several ppb of iodine monoxide in the upper layers of the sunlit snowpack throughout the year. Snow pit samples from Neumayer Station contain up to 700 ng/l of total iodine, representing a sufficient reservoir for these extraordinarily high IO concentrations.

  10. Iodine monoxide in the Antarctic snowpack

    Directory of Open Access Journals (Sweden)

    U. Frieß

    2010-03-01

    Full Text Available Recent ground-based and space borne observations suggest the presence of significant amounts of iodine monoxide in the boundary layer of Antarctica, which are expected to have an impact on the ozone budget and might contribute to the formation of new airborne particles. So far, the source of these iodine radicals has been unknown. This paper presents long-term measurements of iodine monoxide at the German Antarctic research station Neumayer, which indicate that high IO concentrations in the order of 50 ppb are present in the snow interstitial air. The measurements have been performed using multi-axis differential optical absorption spectroscopy (MAX-DOAS. Using a coupled atmosphere – snowpack radiative transfer model, the comparison of the signals observed from scattered skylight and from light reflected by the snowpack yields several ppb of iodine monoxide in the upper layers of the sunlit snowpack throughout the year. Snow pit samples from Neumayer Station contain up to 700 ng/l of total iodine, representing a sufficient reservoir for these extraordinarily high IO concentrations.

  11. Responses of Antarctic Oscillation to global warming

    Science.gov (United States)

    Feng, S.

    2015-12-01

    The Antarctic Oscillation (AAO) is the major annular mode dominates the spatiotemporal variability of the atmospheric circulation in the Southern Hemisphere. This study examined the sensitivity of AAO to future warming by analyzing the outputs of 34 state-of-the-art climate models participating in phase 5 of the Coupled Model Intercomparion Project (CMIP5). The model simulations include the stabilized (RCP4.5) and business as usual (RCP8.5) scenarios as well as the idealized 1% per year increase in atmospheric CO2 to quadrupling (1pctCO2) and an instantaneous quadrupling of CO2 (abrupt4xCO2). We show that the CMIP5 models on average simulate increases in the AAO in every season by 2100 under the RCP4.5 and RCP8.5 scenarios. However, due to the impacts of ozone, aerosol and land use changes, the amplitudes of the projected changes in AAO to future climate scenarios are quit different on different seasons. After the impact of ozone, aerosol and land use changes were removed; it was found that the impact of greenhouse gases (GHGs) on AAO is similar on all seasons. The increases of AAO are accelerating following the increase of GHGs. Our results are also consistent with the simulations of 1pctCO2 and abrupt4xCO2.

  12. Ionospheric irregularities at Antarctic using GPS measurements

    Indian Academy of Sciences (India)

    Sunita Tiwari; Amit Jain; Shivalika Sarkar; Sudhir Jain; A K Gwal

    2012-04-01

    The purpose of this work is to study the behaviour of the ionospheric scintillation at high latitude during geomagnetically quiet and disturbed conditions which is one of the most relevant themes in the space weather studies. Scintillation is a major problem in navigation application using GPS and in satellite communication at high latitudes. Severe amplitude fading and strong scintillation affect the reliability of GPS navigational system and satellite communication. To study the effects of the ionospheric scintillations, GPS receiver installed at Antarctic station Maitri (Geog. 70.76°S; 11.74°E) was used. The data is collected by using GISTM 4004A, NOVATEL’S GPS receiver during March 2008. Studies show that percentage occurrence of phase scintillation is well correlated with geomagnetic activity during the observation period. The result also shows that very intense scintillations can degrade GPS based location determination due to loss of lock of satellites. These findings indicate that the dependence of scintillations and irregularity occurrence on geomagnetic activity is associated with the magnetic local time (MLT). Large number of patches are reported and their activity depends on the magnetic activity index.

  13. Automated detection of Antarctic blue whale calls.

    Science.gov (United States)

    Socheleau, Francois-Xavier; Leroy, Emmanuelle; Pecci, Andres Carvallo; Samaran, Flore; Bonnel, Julien; Royer, Jean-Yves

    2015-11-01

    This paper addresses the problem of automated detection of Z-calls emitted by Antarctic blue whales (B. m. intermedia). The proposed solution is based on a subspace detector of sigmoidal-frequency signals with unknown time-varying amplitude. This detection strategy takes into account frequency variations of blue whale calls as well as the presence of other transient sounds that can interfere with Z-calls (such as airguns or other whale calls). The proposed method has been tested on more than 105 h of acoustic data containing about 2200 Z-calls (as found by an experienced human operator). This method is shown to have a correct-detection rate of up to more than 15% better than the extensible bioacoustic tool package, a spectrogram-based correlation detector commonly used to study blue whales. Because the proposed method relies on subspace detection, it does not suffer from some drawbacks of correlation-based detectors. In particular, it does not require the choice of an a priori fixed and subjective template. The analytic expression of the detection performance is also derived, which provides crucial information for higher level analyses such as animal density estimation from acoustic data. Finally, the detection threshold automatically adapts to the soundscape in order not to violate a user-specified false alarm rate. PMID:26627784

  14. Prospects for surviving climate change in Antarctic aquatic species

    Directory of Open Access Journals (Sweden)

    Peck Lloyd S

    2005-06-01

    Full Text Available Abstract Maritime Antarctic freshwater habitats are amongst the fastest changing environments on Earth. Temperatures have risen around 1°C and ice cover has dramatically decreased in 15 years. Few animal species inhabit these sites, but the fairy shrimp Branchinecta gaini typifies those that do. This species survives up to 25°C daily temperature fluctuations in summer and passes winter as eggs at temperatures down to -25°C. Its annual temperature envelope is, therefore around 50°C. This is typical of Antarctic terrestrial species, which exhibit great physiological flexibility in coping with temperature fluctuations. The rapidly changing conditions in the Maritime Antarctic are enhancing fitness in these species by increasing the time available for feeding, growth and reproduction, as well as increasing productivity in lakes. The future problem these animals face is via displacement by alien species from lower latitudes. Such invasions are now well documented from sub-Antarctic sites. In contrast the marine Antarctic environment has very stable temperatures. However, seasonality is intense with very short summers and long winter periods of low to no algal productivity. Marine animals grow slowly, have long generation times, low metabolic rates and low levels of activity. They also die at temperatures between +5°C and +10°C. Failure of oxygen supply mechanisms and loss of aerobic scope defines upper temperature limits. As temperature rises, their ability to perform work declines rapidly before lethal limits are reached, such that 50% of populations of clams and limpets cannot perform essential activities at 2–3°C, and all scallops are incapable of swimming at 2°C. Currently there is little evidence of temperature change in Antarctic marine sites. Models predict average global sea temperatures will rise by around 2°C by 2100. Such a rise would take many Antarctic marine animals beyond their survival limits. Animals have 3 mechanisms for

  15. Complex Geodetic Research in Ukrainian Antarctic Station "Academician Vernadsky" (Years 2002 - 2005, 2013-2014)

    Science.gov (United States)

    Tretyak, Kornyliy; Hlotov, Volodymyr; Holubinka, Yuriy; Marusazh, Khrystyna

    2016-06-01

    In this paper is given an information about complex geodetic research in Ukrainian Antarctic station "Academician Vernadsky". Research were carried by Lviv polytechnic scientists, during Antarctic expeditions in years 2002 - 2005, 2013, 2014. Main objectives of the studies were: (a) study of the islands glaciers surface volumes changes in Antarctic archipelago and Antarctic Peninsula using terestrial laser scaning and digital terrestrial stereophotogrammetry survey; (b) investigation of Penola strain tectonic fault, using the results of precise GNSS observations.

  16. On the Linkage between Antarctic Surface Water Stratification and Global Deep-Water Temperature

    OpenAIRE

    Keeling, R.F.; Visbeck, Martin

    2011-01-01

    The suggestion is advanced that the remarkably low static stability of Antarctic surface waters may arise from a feedback loop involving global deep-water temperatures. If deep-water temperatures are too warm, this promotes Antarctic convection, thereby strengthening the inflow of Antarctic Bottom Water into the ocean interior and cooling the deep ocean. If deep waters are too cold, this promotes Antarctic stratification allowing the deep ocean to warm because of the input of North Atlantic D...

  17. The spatial extent and dynamics of the Antarctic Cold Reversal

    Science.gov (United States)

    Pedro, Joel B.; Bostock, Helen C.; Bitz, Cecilia M.; He, Feng; Vandergoes, Marcus J.; Steig, Eric J.; Chase, Brian M.; Krause, Claire E.; Rasmussen, Sune O.; Markle, Bradley R.; Cortese, Giuseppe

    2016-01-01

    Antarctic ice cores show that a millennial-scale cooling event, the Antarctic Cold Reversal (14,700 to 13,000 years ago), interrupted the last deglaciation. The Antarctic Cold Reversal coincides with the Bølling-Allerød warm stage in the North Atlantic, providing an example of the inter-hemispheric coupling of abrupt climate change generally referred to as the bipolar seesaw. However, the ocean-atmosphere dynamics governing this coupling are debated. Here we examine the extent and expression of the Antarctic Cold Reversal in the Southern Hemisphere using a synthesis of 84 palaeoclimate records. We find that the cooling is strongest in the South Atlantic and all regions south of 40° S. At the same time, the terrestrial tropics and subtropics show abrupt hydrologic variations that are significantly correlated with North Atlantic climate changes. Our transient global climate model simulations indicate that the observed extent of Antarctic Cold Reversal cooling can be explained by enhanced northward ocean heat transport from the South to North Atlantic, amplified by the expansion and thickening of sea ice in the Southern Ocean. The hydrologic variations at lower latitudes result from an opposing enhancement of southward heat transport in the atmosphere mediated by the Hadley circulation. Our findings reconcile previous arguments about the relative dominance of ocean and atmospheric heat transports in inter-hemispheric coupling, demonstrating that the spatial pattern of past millennial-scale climate change reflects the superposition of both.

  18. Relative changes in krill abundance inferred from Antarctic fur seal.

    Directory of Open Access Journals (Sweden)

    Tao Huang

    Full Text Available Antarctic krill Euphausia superba is a predominant species in the Southern Ocean, it is very sensitive to climate change, and it supports large stocks of fishes, seabirds, seals and whales in Antarctic marine ecosystems. Modern krill stocks have been estimated directly by net hauls and acoustic surveys; the historical krill density especially the long-term one in the Southern Ocean, however, is unknown. Here we inferred the relative krill population changes along the West Antarctic Peninsula (WAP over the 20th century from the trophic level change of Antarctic fur seal Arctocephalus gazella using stable carbon (δ(13C and nitrogen (δ(15N isotopes of archival seal hairs. Since Antarctic fur seals feed preferentially on krill, the variation of δ(15N in seal hair indicates a change in the proportion of krill in the seal's diets and thus the krill availability in local seawater. For the past century, enriching fur seal δ(15N values indicated decreasing krill availability. This is agreement with direct observation for the past ∼30 years and suggests that the recently documented decline in krill populations began in the early parts of the 20th century. This novel method makes it possible to infer past krill population changes from ancient tissues of krill predators.

  19. The Antarctic ozone depletion caused by Erebus volcano gas emissions

    Science.gov (United States)

    Zuev, V. V.; Zueva, N. E.; Savelieva, E. S.; Gerasimov, V. V.

    2015-12-01

    Heterogeneous chemical reactions releasing photochemically active molecular chlorine play a key role in Antarctic stratospheric ozone destruction, resulting in the Antarctic ozone hole. Hydrogen chloride (HCl) is one of the principal components in these reactions on the surfaces of polar stratospheric clouds (PSCs). PSCs form during polar nights at extremely low temperatures (lower than -78 °C) mainly on sulfuric acid (H2SO4) aerosols, acting as condensation nuclei and formed from sulfur dioxide (SO2). However, the cause of HCl and H2SO4 high concentrations in the Antarctic stratosphere, leading to considerable springtime ozone depletion, is still not clear. Based on the NCEP/NCAR reanalysis data over the last 35 years and by using the NOAA HYSPLIT trajectory model, we show that Erebus volcano gas emissions (including HCl and SO2) can reach the Antarctic stratosphere via high-latitude cyclones with the annual average probability Pbarann. of at least ∼0.235 (23.5%). Depending on Erebus activity, this corresponds to additional annual stratospheric HCl mass of 1.0-14.3 kilotons (kt) and SO2 mass of 1.4-19.7 kt. Thus, Erebus volcano is the natural and powerful source of additional stratospheric HCl and SO2, and hence, the cause of the Antarctic ozone depletion, together with man-made chlorofluorocarbons.

  20. Antarctic ecosystems as models for extraterrestrial surface habitats

    Science.gov (United States)

    Wynn-Williams, D. D.; Edwards, H. G. M.

    2000-09-01

    Surface habitats in Antarctic deserts are near the limits of life on Earth and resemble those hypothesized for early Mars. Cyanobacteria dominate the transient riverbeds, stromatolitic sediments in ice-covered lakes, and endolithic communities in translucent rock. There is still no direct evidence of photosynthetic life on early Mars, but cyanobacteria are amongst the earliest microbes detectable in the fossil record for analogous habitats on Earth. Key biomolecules persist in Antarctic microbial habitats, even after extinction by excessive low temperatures, desiccation and UV-B stress within the Ozone Hole. Pigments (or their fossil residues), such as chlorophyll and the UV-protectants scytonemin, carotene and quinones, are good biomarkers. To show not only their presence but also their micro-spatial distribution in situ, we describe the use of FT-Raman spectroscopy with 1064 nm excitation to avoid autofluorescence from the pigments. We report not only the diversity of biomolecules that we have diagnosed from their unique Raman spectra of Antarctic cyanobacterial communities, but also their functional stratification in endolithic communities. Our analyses of Antarctic habitats show the potential of this remote, non-intrusive technique to probe for buried biomolecules on future Mars missions and in Antarctic Lake Vostok, >4 km beneath the Central Ice Sheet, with implications for the putative analogous sub-ice ocean on Europa.

  1. Drying and energy technologies

    CERN Document Server

    Lima, A

    2016-01-01

    This book provides a comprehensive overview of essential topics related to conventional and advanced drying and energy technologies, especially motivated by increased industry and academic interest. The main topics discussed are: theory and applications of drying, emerging topics in drying technology, innovations and trends in drying, thermo-hydro-chemical-mechanical behaviors of porous materials in drying, and drying equipment and energy. Since the topics covered are inter- and multi-disciplinary, the book offers an excellent source of information for engineers, energy specialists, scientists, researchers, graduate students, and leaders of industrial companies. This book is divided into several chapters focusing on the engineering, science and technology applied in essential industrial processes used for raw materials and products.

  2. 27 CFR 9.154 - Chiles Valley.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Chiles Valley. 9.154... Chiles Valley. (a) Name. The name of the viticultural area described in this section is “Chiles Valley.” (b) Approved maps. The appropriate maps for determining the boundary of the Chiles...

  3. Dry etching for microelectronics

    CERN Document Server

    Powell, RA

    1984-01-01

    This volume collects together for the first time a series of in-depth, critical reviews of important topics in dry etching, such as dry processing of III-V compound semiconductors, dry etching of refractory metal silicides and dry etching aluminium and aluminium alloys. This topical format provides the reader with more specialised information and references than found in a general review article. In addition, it presents a broad perspective which would otherwise have to be gained by reading a large number of individual research papers. An additional important and unique feature of this book

  4. Changes in discharge and solute dynamics between a hillslope and a valley-bottom intermittent streams

    Science.gov (United States)

    Bernal, S.; Sabater, F.

    2011-10-01

    We investigated differences on stream water flux as well as on chloride, carbon and nitrogen dynamics between two semiarid nested catchments, one at the hillslope and the other one at the valley-bottom. The two streams were intermittent, yet only the valley-bottom stream was embraced by a riparian forest and a well-developed alluvium with highly conductive coarse sediments. We found that stream water flux decreased by more than 40% from the hillslope to the valley-bottom during hydrological transition periods (from dry-to-wet and from wet-to-dry conditions), coinciding with periods when stream-to-aquifer fluxes prevailed. During the hydrological transition period, stream export of chloride, nitrate, and dissolved organic carbon decreased 34-97% between the hillslope and the valley-bottom catchments. There was a strong correlation between monthly differences in stream discharge and in stream Cl- export between the two catchments. In contrast, monthly differences in stream export for bio-reactive solutes were only partially explained by stream discharge. In annual terms, stream nitrate export from the valley-bottom catchment (0.32 ± 0.12 kg N ha-1 yr-1 - average ± standard deviation) was 30-50% lower than from the hillslope catchment (0.56 ± 0.32 kg N ha-1 yr-1). Although the riparian forest could be an extra source of organic matter to the valley-bottom stream, the annual export of dissolved organic carbon was similar between the two catchments (1.8 ± 1 kg C ha-1 yr-1). Our results suggested that stream hydrology was a strong driver of stream solute export during the hydrological transition period, and that hydrological retention in the alluvial zone could contribute to reduce stream water and solute export under semiarid conditions in the valley-bottom stream.

  5. Constraining Subsurface Structure and Composition Using Seismic Refraction Surveys of Proglacial Valleys in the Cordillera Blanca, Peru

    Science.gov (United States)

    Glas, R. L.; Lautz, L.; McKenzie, J. M.; Mark, B. G.; Baker, E. A.; Aubry-Wake, C.; Somers, L. D.; Wigmore, O.

    2015-12-01

    As tropical glaciers rapidly recede in response to climate change, the storage and discharge of groundwater will play an increasing role in regulating river baseflow, particularly during the dry season, when stream flow is currently sustained predominantly by glacial melt. Little is understood regarding the hydrogeologic processes controlling base flow characteristics of low-gradient proglacial valleys of the Cordillera Blanca in Northwestern Peru, which has the world's highest density of tropical glaciers. To better understand the processes of groundwater storage and discharge in proglacial meadows, we completed seismic refraction surveys in three representative valleys of the Cordillera Blanca range: the Quilcayhuanca, Yanamarey, and Pachacoto valleys. The locations of survey transects were chosen based on locations of previous sediment core sampling, GPR lines, and quantification of groundwater-surface water interaction derived from dye and temperature tracing experiments. The seismic surveys consisted of 48 vertical component geophones with 2.5 m spacing. Across the three representative valleys a total of 15 surveys were conducted, covering a distance of 1800 m in cross, down, and oblique-valley directions. Preliminary interpretation of the seismic refraction data indicates a maximum imaging depth of 16 m below land surface, and a transition from glacio-lacustrine sediments to buried saturated talus at a depth of 6 m in the Quilcayhuanca valley. The organic-rich glacio-lacustrine sediments in the Yanamarey valley have seismic velocities ranging from 300 to 800 m/s and are >16 m in thickness at mid- valley. Weathered metasedimentary bedrock in the Pachacoto valley was imaged at ~5 m below the valley surface, exhibiting a p-wave velocity of 3400 m/s. The knowledge of hydrogeologic structure derived from seismic refraction surveys will provide crucial boundary conditions for future groundwater models of the valleys of the Cordillera Blanca.

  6. The Future of Silicon Valley

    Institute of Scientific and Technical Information of China (English)

    Joseph Leu

    2006-01-01

    @@ By the end of 1984, Silicon Valley was going through the down cycle fol lowing the PC boom. A hundred PC companies wanted just 10 percent of the market, wanting to strike it rich, as rich as the Apple IPO (Initial Public Of fering) -the Google celebrity IPO of its day.

  7. Introduction of hydrogen vehicles in Kathmandu Valley. A clean and sustainable way of transportation

    Energy Technology Data Exchange (ETDEWEB)

    Ale, B.B. [Department of Mechanical Engineering, Pulchowk Campus, Institute of Engineering, Tribhuvan University (Nepal); Bade Shrestha, S.O. [Department of Mechanical and Aeronautical Engineering, Western Michigan University, 1903 West Michigan Avenue, Kalamazoo, MI 49008 (United States)

    2009-06-15

    Air quality of Kathmandu Valley, the capital of Nepal, was one of the worse among the big cites in the world. The air quality situation was becoming more critical due to the substantial increase in the conventional fueled vehicles in the valley each year. The bowl-like topography and generally low speeds of wind during the dry seasons create poor dispersion conditions, augmenting the air pollution problem further. The pollution is expected to quadruple by 2020 from the 2005 level in as business as usual scenario. The main source of the pollution in the valley is motor vehicle emissions. The paper highlights the different level of air pollution and emission reductions by introducing hydrogen fuel vehicles in Kathmandu Valley. The entire fleet of vehicles in the valley can be fueled by hydrogen produced from the national hydroelectricity of Nepal using only less than 50% of its surplus energy. This will reduce about 700,000 tonnes of carbon emission in the valley in 2020. In addition, production of hydrogen using the surplus hydroelectricity of Nepal will improve load factor of the grid, and save a substantial amount of hard currency used to import the petroleum fuel in the country. As Nepal is one of the most hydropower potential countries in the world, with a 80,000 MW potential capacity, hydrogen production is renewable, sustainable and pollution free. (author)

  8. Antarctic DNA moving forward: genomic plasticity and biotechnological potential.

    Science.gov (United States)

    Martínez-Rosales, Cecilia; Fullana, Natalia; Musto, Héctor; Castro-Sowinski, Susana

    2012-06-01

    Antarctica is the coldest, driest, and windiest continent, where only cold-adapted organisms survive. It has been frequently cited as a pristine place, but it has a highly diverse microbial community that is continually seeded by nonindigenous microorganisms. In addition to the intromission of 'alien' microorganisms, global warming strongly affects microbial Antarctic communities, changing the genes (qualitatively and quantitatively) potentially available for horizontal gene transfer. Several mobile genetic elements have been described in Antarctic bacteria (including plasmids, transposons, integrons, and genomic islands), and the data support that they are actively involved in bacterial evolution in the Antarctic environment. In addition, this environment is a genomic source for the identification of novel molecules, and many investigators have used culture-dependent and culture-independent approaches to identify cold-adapted proteins. Some of them are described in this review. We also describe studies for the design of new recombinant technologies for the production of 'difficult' proteins. PMID:22360528

  9. Terrestrial 81Kr-Kr ages of Antarctic meteorites

    International Nuclear Information System (INIS)

    The production rate of 38Ar in meteorites-P(38)-has been determined, as a function of the sample's chemical composition, from 81Kr-Kr exposure ages of four eucrite falls. The cosmogenic 78Kr/83Kr ratio is used to estimate the shielding dependence of P(38). From the ''true'' 38Ar exposure ages and the apparent 81Kr-Kr exposure ages of nine Antarctic eucrite finds, terrestrial ages are calculated. The distribution of terrestrial ages of Allan Hills meteorites is discussed. Meteorites from this blue ice field have two sources: Directly deposited falls and meteorites transported to the Allan Hills inside the moving Antarctic ice sheet. During the surface residence time meteorites decompose due to weathering processes. The weathering ''half-life'' is about 1.6 x 105 a. From the different age distributions of Allan Hills and Yamato meteorites, it is concluded that meteorite concentrations of different Antarctic ice fields need different explanations. (author)

  10. Depletion in Antarctic ozone and associated climatic change

    International Nuclear Information System (INIS)

    Perhaps the most significant discovery in the atmospheric sciences in the last decade has been the observation of large decreases in ozone. These losses in ozone occur during austral spring, and from 1979 the severity of the depletion increased non-monotonically until September of 1987 when the lowest column ozone amounts ever recorded were observed in Antarctica. While the surprising ozone hole in the remote icy continent of Antarctica emphasizes the potential importance and complexity of processes in the high latitude stratosphere, it also motivated this study on the nature of greenhouse effect on polar climate due to perturbations in column ozone amount in association with observed increases in other trace gases in the Antarctic atmosphere. The authors have examined the potential climatic effects of changes in the concentration of greenhouse gases on thermal structure of the Antarctic atmosphere using both steady-state and time-dependent climate models. When the authors incorporate the greenhouse effect of increases in methane, nitrous oxide, carbon dioxide and chlorofluorocarbons in association with decrease in ozone at the levels of maximum concentration in their radiative flux computations for the Antarctic region, the net result is a surface warming which is in fair agreement with that inferred from mean Antarctic temperature series. Further, the stratospheric cooling due to the ozone hole phenomenon is not only restricted to low and middle stratosphere but also extends deep into the upper Antarctic stratosphere, particularly in the beginning of November. In view of this, it is possible that the polar stratospheric warming phenomenon associated with planetary wave events could be significantly disturbed by ozone depletion in the Antarctic atmosphere, leading to appreciable perturbations in the general circulation

  11. Antarctic Porifera database from the Spanish benthic expeditions

    Directory of Open Access Journals (Sweden)

    Pilar Rios

    2014-04-01

    Full Text Available The information about the sponges in this dataset is derived from the samples collected during five Spanish Antarctic expeditions: Bentart 94, Bentart 95, Gebrap 96, Ciemar 99/00 and Bentart 2003. Samples were collected in the Antarctic Peninsula and Bellingshausen Sea at depths ranging from 4 to 2044 m using va­rious sampling gears.The Antarctic Porifera database from the Spanish benthic expeditions is unique as it provides in­formation for an under-explored region of the Southern Ocean (Bellingshausen Sea. It fills an information gap on Antarctic deep-sea sponges, for which there were previously very few data.This phylum is an important part of the Antarctic biota and plays a key role in the structure of the Antarctic marine benthic community due to its considerable diversity and predominance in different areas. It is often a dominant component of Southern Ocean benthic communities.The quality of the data was controlled very thoroughly with GPS systems onboard the R/V Hesperides and by checking the data against the World Porifera Database (which is part of the World Register of Marine Species, WoRMS. The data are therefore fit for completing checklists, inclusion in biodivers­ity pattern analysis and niche modelling. The authors can be contacted if any additional information is needed before carrying out detailed biodiversity or biogeographic studies.The dataset currently contains 767 occurrence data items that have been checked for systematic reliability. This database is not yet complete and the collection is growing. Specimens are stored in the author’s collection at the Spanish Institute of Oceanography (IEO in the city of Gijón (Spain. The data are available in GBIF.

  12. Antarctic Porifera database from the Spanish benthic expeditions.

    Science.gov (United States)

    Rios, Pilar; Cristobo, Javier

    2014-01-01

    THE INFORMATION ABOUT THE SPONGES IN THIS DATASET IS DERIVED FROM THE SAMPLES COLLECTED DURING FIVE SPANISH ANTARCTIC EXPEDITIONS: Bentart 94, Bentart 95, Gebrap 96, Ciemar 99/00 and Bentart 2003. Samples were collected in the Antarctic Peninsula and Bellingshausen Sea at depths ranging from 4 to 2044 m using various sampling gears. The Antarctic Porifera database from the Spanish benthic expeditions is unique as it provides information for an under-explored region of the Southern Ocean (Bellingshausen Sea). It fills an information gap on Antarctic deep-sea sponges, for which there were previously very few data. This phylum is an important part of the Antarctic biota and plays a key role in the structure of the Antarctic marine benthic community due to its considerable diversity and predominance in different areas. It is often a dominant component of Southern Ocean benthic communities. The quality of the data was controlled very thoroughly with GPS systems onboard the R/V Hesperides and by checking the data against the World Porifera Database (which is part of the World Register of Marine Species, WoRMS). The data are therefore fit for completing checklists, inclusion in biodiversity pattern analysis and niche modelling. The authors can be contacted if any additional information is needed before carrying out detailed biodiversity or biogeographic studies. The dataset currently contains 767 occurrence data items that have been checked for systematic reliability. This database is not yet complete and the collection is growing. Specimens are stored in the author's collection at the Spanish Institute of Oceanography (IEO) in the city of Gijón (Spain). The data are available in GBIF. PMID:24843257

  13. Topological spin and valley pumping in silicene.

    Science.gov (United States)

    Luo, Wei; Sheng, L; Wang, B G; Xing, D Y

    2016-01-01

    We propose to realize adiabatic topological spin and valley pumping by using silicene, subject to the modulation of an in-plane ac electric field with amplitude Ey and a vertical electric field consisting of an electrostatic component and an ac component with amplitudes and . By tuning and , topological valley pumping or spin-valley pumping can be achieved. The low-noise valley and spin currents generated can be useful in valleytronic and spintronic applications. Our work also demonstrates that bulk topological spin or valley pumping is a general characteristic effect of two-dimensional topological insulators, irrelevant to the edge state physics. PMID:27507592

  14. Antarctic Ozone Hole on September 17, 2001

    Science.gov (United States)

    2002-01-01

    Satellite data show the area of this year's Antarctic ozone hole peaked at about 26 million square kilometers-roughly the size of North America-making the hole similar in size to those of the past three years, according to scientists from NASA and the National Oceanic and Atmospheric Administration (NOAA). Researchers have observed a leveling-off of the hole size and predict a slow recovery. Over the past several years the annual ozone hole over Antarctica has remained about the same in both its size and in the thickness of the ozone layer. 'This is consistent with human-produced chlorine compounds that destroy ozone reaching their peak concentrations in the atmosphere, leveling off, and now beginning a very slow decline,' said Samuel Oltmans of NOAA's Climate Monitoring and Diagnostics Laboratory, Boulder, Colo. In the near future-barring unusual events such as explosive volcanic eruptions-the severity of the ozone hole will likely remain similar to what has been seen in recent years, with year-to-year differences associated with meteorological variability. Over the longer term (30-50 years) the severity of the ozone hole in Antarctica is expected to decrease as chlorine levels in the atmosphere decline. The image above shows ozone levels on Spetember 17, 2001-the lowest levels observed this year. Dark blue colors correspond to the thinnest ozone, while light blue, green, and yellow pixels indicate progressively thicker ozone. For more information read: 2001 Ozone Hole About the Same Size as Past Three Years. Image courtesy Greg Shirah, GSFC Scientific Visualization Studio, based on data from the TOMS science team

  15. Viral distribution and activity in Antarctic waters

    Science.gov (United States)

    Guixa-Boixereu, Núria; Vaqué, Dolors; Gasol, Josep M.; Sánchez-Cámara, Jaime; Pedrós-Alió, Carlos

    Variability in abundance of virus-like particles (VLP), VLP decay rates and prokaryotic mortality due to viral infection were determined in three Antarctic areas: Bellingshausen Sea, Bransfield Strait and Gerlache Strait, during December 1995 and February 1996. VLP abundance showed very small spatial variability in the three areas (7×10 6-2×10 7 VLP ml -1). VLP abundance, on the other hand, decreased one order of magnitude from the surface to the bottom, in two stations where deep vertical profiles were sampled. Low seasonal variability in VLP abundance was found when comparing each area separately. Diel VLP variability was also very low. VLP abundance showed the lowest values when solar irradiation was maximal, in two of the three stations where diel cycles were examined. Viral decay rates (VDR) were determined using KCN in two kinds of experiments. Type 1 experiments were performed in 6 stations to determine viral decay. Type 2 experiments were carried out in 2 stations to examine the influence of temperature and organic matter concentration on viral decay. VDR was not influenced by these parameters. Prokaryotic mortality due to viral infection was always higher than that due to bacterivores in the stations where both factors of prokaryotic mortality were measured. Viral infection accounted for all the prokaryotic heterotrophic production in Bellingshausen Sea and Gerlache Strait and for half of the prokaryotic heterotrophic production in Bransfield Strait. These high values of prokaryotic mortality due to viral infection are difficult to reconcile in nature, and more work is necessary to determine the mechanisms involved in the disappearance of viruses.

  16. Perspective with Landsat Overlay: Antelope Valley, California

    Science.gov (United States)

    2000-01-01

    Antelope Valley is bounded by two of the most active faults in California: the Garlock fault, which fronts the distant mountains in this view, and the San Andreas fault, part of which is seen bounding the mountains in the left foreground. In this view, Antelope Valley is in the foreground, the Tehachapi Mountains form the left skyline, and ranges within the southernmost Sierra Nevada form the right skyline. Antelope Valley is directly north of Los Angeles and is the westernmost part of the Mojave Desert. It is a closed basin. Stream flow here ends at Rosamond and Rogers dry lakes, which appear bright white. Dry lakes like these are common where tectonic activity raises and lowers parts of the Earth's crust, and thus the topographic surface, faster than stream flow can fill depressions with water, and then overflow and cut escape channels to other basins and eventually to the sea. The Sierra Nevada, the Tehachapi, and other mountains generally to the west create a rain shadow desert here. Thus, the area definitely has the active tectonics and low rainfall combination that leads to closed basin topography.This perspective view was generated by draping a Landsat satellite image over a preliminary topographic map from the Shuttle Radar Topography Mission. Shading of the SRTM elevation model was added to enhance topographic appearance. Landsat has been providing visible and infrared views of the Earth since 1972. SRTM elevation data matches the 30 meter resolution of most Landsat images and will substantially help in analyses of the large and growing Landsat image archive.The elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three

  17. Rapid Drying Concrete

    OpenAIRE

    ECT Team, Purdue

    2015-01-01

    One of the essential problems that are faced during construction is the drying of concrete and the presence of moisture which affects floor coverings that need to be placed. The rapid-drying characteristic in Aridusâ concrete allows for the quick reduction of moisture vapor that travels through the concrete pores of the concrete.

  18. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Health Find an Ophthalmologist Academy Store Eye Health A-Z Symptoms Glasses & Contacts Tips & Prevention News Ask an Ophthalmologist Español Eye Health / Eye Health A-Z Dry Eye Sections What Is Dry Eye? Causes ...

  19. Hydrochemical characteristic of different modifications of Antarctic waters

    Science.gov (United States)

    Batrak, K. V.

    2008-06-01

    The report considers the distribution of several hydrochemical components (dissolved oxygen, mineral phosphorus, dissolved silicon, and nitrate nitrogen) depending on the disposition of different structural water modifications constituting the unified Antarctic structural type. It is shown that the character of the silicon distribution in the waters of the South Polar zone is mainly determined by large-scale circulation features. The distribution of mineral phosphorus and nitrate nitrogen is characterized by a certain patchiness related to the photosynthesis intensity. An attempt was made to follow the supply and transformation of dissolved silicon, nitrates, and phosphates in the Antarctic.

  20. Stable isotopic biogeochemistry of carbon and nitrogen in a perennially ice-covered Antarctic lake

    Science.gov (United States)

    Wharton, R. A. Jr; Lyons, W. B.; Des Marais, D. J.; Wharton RA, J. r. (Principal Investigator)

    1993-01-01

    Lake Hoare (77 degrees 38' S, 162 degrees 53' E) is an amictic, oligotrophic, 34-m-deep, closed-basin lake in Taylor Valley, Antarctica. Its perennial ice cover minimizes wind-generated currents and reduces light penetration, as well as restricts sediment deposition into the lake and the exchange of atmospheric gases between the water column and the atmosphere. The biological community of Lake Hoare consists solely of microorganisms -- both planktonic populations and benthic microbial mats. Lake Hoare is one of several perennially ice-covered lakes in the McMurdo Dry Valleys that represent the end-member conditions of cold desert and saline lakes. The dry valley lakes provide a unique opportunity to examine lacustrine processes that operate at all latitudes, but under an extreme set of environmental conditions. The dry valley lakes may also offer a valuable record of catchment and global changes in the past and present. Furthermore, these lakes are modern-day equivalents of periglacial lakes that are likely to have been common during periods of glacial maxima at temperate latitudes. We have analyzed the dissolved inorganic carbon (DIC) of Lake Hoare for delta 13C and the organic matter of the sediments and sediment-trap material for delta 13C and delta 15N. The delta 13C of the DIC indicates that 12C is differentially removed in the shallow, oxic portions of the lake via photosynthesis. In the anoxic portions of the lake (27-34 m) a net addition of 12C to the DIC pool occurs via organic matter decomposition. The dissolution of CaCO3 at depth also contributes to the DIC pool. Except near the Canada Glacier where a substantial amount of allochthonous organic matter enters the lake, the organic carbon being deposited on the lake bottom at different sites is isotopically similar, suggesting an autochthonous source for the organic carbon. Preliminary inorganic carbon flux calculations suggest that a high percentage of the organic carbon fixed in the water column is

  1. Assessment of surface water quality of inland valleys for cropping in SW Nigeria

    Science.gov (United States)

    Aboyeji, O. S.; Ogunkoya, O. O.

    2015-07-01

    Inland valley agro-ecosystems which are a category of wetlands have potential for sustainable crop production relative to uplands. A major challenge to their utilisation in the study area is their heterogeneity in hydrology, morphology, soil types and agro-economy. The study assessed the surface water quality of three typologies of the agro-ecosystems—amphitheatre-like valley-heads (Am), valley-side (VS), and low depression (LD)—for cropping. Surface water of six sites were sampled during the wet and dry seasons. The physicochemical properties and metal concentrations of the samples were analysed. Descriptive statistics and water quality indices were used to assess the suitability of the waters of the agro-ecosystems for cropping. Results showed that the valleys have neutral to slightly alkaline waters. Values of physicochemical parameters are generally within the acceptable range for cropping. The concentration of major cations varied across the inland valley types, but exhibited similar characteristics within each valley. The dominance of the major cations is in the order of Na > Ca > K > Mg. ANOVA results indicated that there is no significant difference in the concentration of heavy metals across the valleys (F = 2.044, p = 0.138, α = 0.05). Generally, most of the physicochemical parameters and trace metals have low concentrations and are non-toxic to plants. Values of water quality indices (sodium adsorption ratio, soluble sodium percentage, total dissolved solids and permeability index) indicated that the concentrations of minerals in waters across the valley typologies are generally within permissible limits for cropping.

  2. Characterising Antarctic and Southern Ocean Lithosphere with Magnetic and Gravity Imaging of East Antarctic Rift Systems

    Science.gov (United States)

    Vaughan, A. P.; Kusznir, N. J.; Ferraccioli, F.; Jordan, T. A.; Purucker, M. E.; Golynsky, A. V.; Rogozhina, I.

    2012-12-01

    Since the International Geophysical Year (1957), a view has prevailed that the lithospheric structure of East Antarctica is relatively homogeneous, forming a geological block of largely cratonic nature, consisting of a mosaic of Precambrian terranes, stable since the Pan-African orogeny ~500 million years ago. Recent recognition of a continental-scale rift system cutting the East Antarctic interior indicates that this is incorrect, and has crystallised an alternative view of much more recent geological activity with important implications for tectonic reconstructions and controls on ice sheet formation and stability. The newly defined East Antarctic Rift System 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 pioneered by Golynsky & Golynsky indicates that further rift zones may extend the East Antarctic Rift System into widely distributed extension zones within the continent. We have carried out a pilot study, using a newly developed gravity inversion technique with existing public domain satellite data, which shows that East Antarctica consists of distinct crustal thickness provinces with anomalously thick areas separated by thin, possibly rifted crust and overall high average thickness. Understanding the nature of crustal thickness in East Antarctica is critical because: 1) Better understanding of crustal thickness in Antarctica, especially along the ocean-continent transition (OCT), will make it possible to improve the plate reconstruction fit between Antarctica, Australia and India in Gondwana and also refine constraints on how and when these continents separated; 2) crustal thickness provinces can be used to aid supercontinent reconstructions and provide new assessments of the influence of basement architecture and mechanical properties on rifting processes; 3) tracking rift zones through

  3. Persistent organohalogen contaminant burdens in Antarctic krill (Euphausia superba) from the eastern Antarctic sector: A baseline study

    International Nuclear Information System (INIS)

    A baseline for persistent organohalogen compound (POC) accumulation in the Antarctic keystone species, Antarctic krill (Euphausia superba) has been established for a 50 deg. longitudinal range of the eastern Antarctic sector. Samples of adult krill, caught from 12 sites distributed between 30 deg. and 80 deg. E (60-70 deg. S), were analysed for > 100 organohalogen compounds including chlorinated pesticides, polychlorinated biphenyls (PCBs), polybrominated organic compounds and polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs). Organochlorine pesticides dominated measured krill contaminant burdens with hexachlorobenzene (HCB) as the single most abundant compound quantified. Krill HCB concentrations were comparable to those detected at this trophic level in both the Arctic and temperate northwest Atlantic, lending support for the hypothesis that HCB will approach global equilibrium at a faster rate than other POCs. Para, para'-dichlorodiphenylethene (p,p'-DDE) was detected at notable concentrations. Measurements of DDT and its degradation products provide an important baseline for monitoring the temporal and geographical influence of renewed, DDT usage for malaria-control in affected southern hemisphere countries. In contrast to the Arctic, PCBs did not feature prominently in contaminant burdens of Antarctic krill. The major commercial polybrominated diphenyl ether (PBDE) congeners -99 and -47 were quantified at low background levels with clear concentration spikes observed at around 70 deg. E , in the vicinity of modern, active research stations. The likelihood that local anthropogenic activities are supplementing low PBDE levels, delivered otherwise primarily via long range environmental transport, is discussed. The suspected naturally occurring brominated organic compound, 2,4,6-tribromoanisole (TBA), was a ubiquitous contaminant in all samples whereas the only PCDD/Fs quantifiable were trace levels of octachlorodibenzo-p-dioxin (OCDD) and 1,2,3

  4. Antarctic Pumpdown---a New Geoengineering Concept for Capturing and Storing Atmospheric Carbon Dioxide

    Science.gov (United States)

    Beget, J. E.

    2014-12-01

    Growing concentrations of carbon dioxide in the atmosphere are increasing global temperatures. This is projected to impact human society in negative ways. Multiple geoengineering approaches have been suggested that might counteract problems created by greenhouse warming, but geoengineering itself can be problematic as some proposed methods would pose environmental risks to the oceans, atmosphere, and biosphere. I propose a new approach that would remove CO2 from the atmosphere and store it in the cryosphere. Carbon dioxide would be captured by seeding the atmosphere over a designated small region of central Antarctica with monoethanolamine (MEA), a well known compound commonly used for CO2 capture in submarines and industrial processes. Monoethanolamine captures and retains carbon dioxide until it encounters water. Because MEA crystals are stable when dry, they would fall from the atmosphere just in the local area where the seeding is done, and they would be naturally buried by snowfalls and preserved in the upper parts of the East Antarctic Ice Sheet, where thawing does not occur. The carbon dioxide removed from the atmosphere by this process could reside safely in this geologic reservoir for thousands of years, based on known flow characteristic of the ice sheet. Also, carbon dioxide stored in this way could be recovered in the future by drilling into the ice sheet to the frozen storage zone. The CO2 Antarctic Pumpdown (CAP) concept could potentially be used to stabilize or reduce the amount of carbon dioxide in the atmosphere, and then to store the carbon dioxide safely and inexpensively in a stable geologic reservoir

  5. Dry well cooling device

    International Nuclear Information System (INIS)

    A plurality of blowing ports with introduction units are disposed to a plurality of ducts in a dry well, and a cooling unit comprising a cooler, a blower and an isolating valve is disposed outside of the dry well. Cooling air and the atmosphere in the dry well are mixed to form a cooling gas and blown into the dry well to control the temperature. Since the cooling unit is disposed outside of the dry well, the maintenance of the cooling unit can be performed even during the plant operation. In addition, since dampers opened/closed depending on the temperature of the atmosphere are disposed to the introduction units for controlling the temperature of the cooling gas, the temperature of the atmosphere in the dry well can be set to a predetermined level rapidly. Since an axial flow blower is used as the blower of the cooling unit, it can be contained in a ventilation cylinder. Then, the atmosphere in the dry well flowing in the ventilation cylinder can be prevented from leaking to the outside. (N.H.)

  6. Drying plant waste

    International Nuclear Information System (INIS)

    Under the repository storage conditions of Eram and Konrad, waste packages designed for permanent storage must not contain or release freely mobile liquids, except for the minimum residues attainable by reasonable efforts or unavoidable. In accordance with a directive issued by the German Federal Ministry for the Environment (BMU), waste conditioning must be carried out so as to minimize waste volumes and, if possible, on the site where the waste arises. Liquid waste is conditioned most effectively by drying. At the present time, various different processes for drying liquid waste are employed as reflected by the state of the art: The Robe process; roller drying; the RDA process; Favorit; in-drum drying; and HPA liquid waste drying with make-up feed. The HPA process offers these advantages: Drying under atmospheric conditions, which means high level of dryness (freely mobile and releasable water is removed); the residual water content is 10%; isothermal drying by hot air, which produces monoliths guaranteeing high strength of the final product and maximum volume reduction by simple process technology; there is no local superheating; contamination hazards are minimized by drying in the repository storage package; consequently, there is no filling step, and vapors are collected separately; the level of automation is high, e.g. with fully automated control from a shielded control console with video monitoring capability; the high standard of documentation allows instant process visualization throughout the drying process along with easy process control; high flexibility is achieved in mobile and stationary plants, respectively, with the added possibility of service functions being provided; modular small compact versions are also available. (orig.)

  7. A stable isotope reconnaissance of groundwater resources in the Kathmandu Valley, Nepal

    International Nuclear Information System (INIS)

    Groundwater, surface water, spring water, and precipitation obtained during the monsoon season in the Kathmandu Valley of central Nepal were analysed for the stable environmental isotopes oxygen-18 (18O) and deuterium (2H). The distributions of the isotopes in the hydrologic cycle suggest that valley groundwaters have different origins. The Kathmandu Valley is a tectonic basin in the middle hill region of Nepal, 80 km south of the crest of the Himalayan Mountains. The 600 km2 bowl-like valley contains more than 400 m of lacustrine and fluvial sediments. The elevation of the relatively flat valley floor is roughly 1300 m. Steep hills surrounding the valley rise generally to 1600 m, and to a maximum of 2760 m. The small mountain reservoirs that supplied 80% of the drinking water for the city of Kathmandu (population exceeds 200 000) no longer meet demand during the dry season. New production wells show high levels of dissolved iron (> 2 mg/L) and high acidity (pH 18O and δ2H. The isotopically lightest sample was -10.4 and -74, and the heaviest was -6.9 and -55. Light surface waters originating in northern and southern uplands plot near the world meteoric water line. Waters with intermediate values, groundwater in the northern area of the valley and several small rivers, plot along a possible evaporation or mixing line. The heaviest waters, collected from a small river flowing from the east, groundwater in the centre of the valley, and deep groundwater containing natural gas in the southwestern area of the valley, all have signatures similar to those reported from the first range of the Himalayan uplift, roughly 1000 m lower in elevation. A volume weighted composite sample of rain water collected in the city of Kathmandu from August 22 to September 12, 1986 had values of -8.0 and -58. One overnight storm produced more than 10 cm of rain with values of -1.8 and -6. It is assumed that large variations between individual precipitation events are naturally averaged to

  8. The Owens Valley solar array

    International Nuclear Information System (INIS)

    Solar microwave emission contains essential information for the study of the coronal magnetic structure of active regions and of thermal and nonthermal flare electrons. To exploit this potential requires BOTH imaging and spectroscopy with sufficient resolution to resolve spatial and spectral features. The VLA provides excellent solar imaging (when in the C and D configurations) but inadequate spectral coverage. The existing Owens Valley system has excellent spectral coverage but imaging that is adequate only for very simple sources. The Owens Valley system is currently undergoing an expansion, which when completed in October 1990 will provide a SOLAR-DEDICATED 5 antenna array (10 baselines). By using frequency-synthesis, this will provide a significant imaging capability in addition to its current spectral coverage

  9. Magic nuclei in superheavy valley

    OpenAIRE

    Bhuyan, M.; Patra, S. K.

    2011-01-01

    An extensive theoretical search for the proton magic number in the superheavy valley beyond $Z=$82 and corresponding neutron magic number after $N=$126 is carried out. For this we scanned a wide range of elements $Z=112-130$ and their isotopes. The well established non-relativistic Skryme-Hartree-Fock and Relativistic Mean Field formalisms with various force parameters are used. Based on the calculated systematics of pairing gap, two neutron separation energy and the shell correction energy f...

  10. Local scaling characteristics of Antarctic surface layer turbulence

    Directory of Open Access Journals (Sweden)

    S. Basu

    2010-03-01

    Full Text Available Over the past years, several studies have validated Nieuwstadt's local scaling hypothesis by utilizing turbulence observations from the mid-latitude, nocturnal stable boundary layers. In this work, we probe into the local scaling characteristics of polar, long-lived stable boundary layers by analyzing turbulence data from the South Pole region of the Antarctic Plateau.

  11. Evaluating Wind Power Potential in the Spanish Antarctic Base (BAE)

    International Nuclear Information System (INIS)

    The objective of the work is to model wind field in the surroundings of the Spanish Antarctic Base (BAE in the following). The need of such a work comes from the necessity of an energy source able to supply the energy demand in the BAE during the Antarctic winter. When the BAE is in operation (in the Antarctic summer) the energy supply comes from a diesel engine. In the Antarctic winter the base is closed, but the demand of energy supply is growing up every year because of the increase in the number of technical and scientific machines that remain in the BAE taking different measurements. For this purpose the top of a closed hill called Pico Radio, not perturbed by close obstacles, has been chosen as the better site for the measurements. The measurement station is made up with a sonic anemometer and a small wind generator to supply the energy needed by the sensors head heating of the anemometer. This way, it will be also used as a proof for the suitability of a wind generator in the new chosen site, under those special climatic conditions.(Author) 3 refs

  12. Recent Rapid Regional Climate Warming on the Antarctic Peninsula

    Science.gov (United States)

    Vaughan, D. G.; Marshall, G. J.; Connolley, W. M.; Parkinson, C.; Mulvaney, R.; Hodgson, D. A.; King, J. C.; Pudsey, C. J.; Turner, J.

    2002-12-01

    The Intergovernmental Panel on Climate Change (IPCC) confirmed that global warming was 0.6 ñ 0.2 degrees C during the 20th Century and cited increases in greenhouse gases as a likely contributor. But this average conceals the complexity of observed climate change, which is seasonally biased, decadally variable and geographically patchy. In particular, over the last 50 years three high-latitude areas have undergone recent rapid regional (RRR) warming ? substantially more rapid than the global mean. We discuss the spatial and temporal significance of RRR warming in one area, the Antarctic Peninsula. New analyses of station records show no ubiquitous polar amplification of global warming but significant RRR warming on the Antarctic Peninsula. We investigate the likelihood that this could be amplification of a global warming, and use climate-proxy data to indicate that this RRR warming on the Antarctic Peninsula is unprecedented over the last two millennia and unlikely to be a natural mode of variability. We can show a strong connection between RRR warming and reduced sea-ice duration in an area on the west of the Antarctic Peninsula, but here we cannot yet distinguish cause and effect. Thus for the present we cannot determine which process causes the RRR warming, and until the mechanism initiating and sustaining it is understood, and is convincingly reproduced in climate models, we lack a sound basis for predicting climate change in this region over the coming century.

  13. Pioneering work of CAS researchers in Antarctic expedition

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ The first observatory at Dome A On 12 January, China scientific expedition to Antarctica succeeded for a second time in climbing up to Dome A, the highest Antarctic icecap peak. A similar feat was made by Chinese scientists about three years ago in January 2005, leaving first human footprints there.

  14. 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 dynami

  15. Occurrence of a taurine derivative in an antarctic glass sponge.

    Science.gov (United States)

    Carbone, Marianna; Núñez-Pons, Laura; Ciavatta, M Letizia; Castelluccio, Francesco; Avila, Conxita; Gavagnin, Margherita

    2014-04-01

    The n-butanol extract of an Antarctic hexactinellid sponge, Anoxycalyx (Scolymastra) joubini, was found to contain a taurine-conjugated anthranilic acid, never reported so far either as a natural product or by synthesis. The compound was inactive against human cancer cells in an in vitro growth inhibitory test, and also showed no antibacterial activity. PMID:24868857

  16. An Antarctic Circumpolar Current driven by surface buoyancy forcing

    Science.gov (United States)

    Hogg, Andrew McC.

    2010-12-01

    Simulations of an idealised, but eddy-resolving, channel model of the Antarctic Circumpolar Current (ACC) are used to investigate the sensitivity of ACC transport to wind and surface buoyancy forcing. The results are consistent with theoretical predictions of the eddy-saturated limit, where transport is independent of wind stress. In this parameter regime, buoyancy forcing provides the primary control over ACC transport.

  17. Molecular evolution of hemoglobins of Antarctic fishes (Notothenioidei)

    NARCIS (Netherlands)

    Stam, W.T.; Beintema, J.J; D Avino, R.; Tamburrini, M.; di Prisco, G.

    1997-01-01

    Amino acid sequences of alpha- and beta-chains of human hemoglobin and of hemoglobins of coelacanth and 24 teleost fish species, including 11 antarctic and two temperate Notothenioidei, were analyzed using maximum parsimony. Trees were derived for the alpha- and beta-chains separately and for tandem

  18. Maneuver simulation model of an experimental hovercraft for the Antarctic

    Science.gov (United States)

    Murao, Rinichi

    Results of an investigation of a hovercraft model designed for Antarctic conditions are presented. The buoyancy characteristics, the propellant control system, and simulation model control are examined. An ACV (air cushion vehicle) model of the hovercraft is used to examine the flexibility and friction of the skirt. Simulation results are presented which show the performance of the hovercraft.

  19. 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.)

  20. Antarctic Cenozoic climate history from sedimentary records: ANDRILL and beyond.

    Science.gov (United States)

    McKay, R M; Barrett, P J; Levy, R S; Naish, T R; Golledge, N R; Pyne, A

    2016-01-28

    Mounting evidence from models and geological data implies that the Antarctic Ice Sheet may behave in an unstable manner and retreat rapidly in response to a warming climate, which is a key factor motivating efforts to improve estimates of Antarctic ice volume contributions to future sea-level rise. Here, we review Antarctic cooling history since peak temperatures of the Middle Eocene Climatic Optimum (approx. 50 Ma) to provide a framework for future initiatives to recover sediment cores from subglacial lakes and sedimentary basins in Antarctica's continental interior. While the existing inventory of cores has yielded important insights into the biotic and climatic evolution of Antarctica, strata have numerous and often lengthy time breaks, providing a framework of 'snapshots' through time. Further cores, and more work on existing cores, are needed to reconcile Antarctic records with the more continuous 'far-field' records documenting the evolution of global ice volume and deep-sea temperature. To achieve this, we argue for an integrated portfolio of drilling and coring missions that encompasses existing methodologies using ship- and sea-ice-/ice-shelf-based drilling platforms as well as recently developed seafloor-based drilling and subglacial access systems. We conclude by reviewing key technological issues that will need to be overcome. PMID:26667911

  1. 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 AND-1

  2. Properties of pears dried with different drying processes.

    OpenAIRE

    Guiné, Raquel; Barroca, Maria João; Lopes, Paulo; Silva, Vitor; Lima, Maria João; Ferreira, Dulcineia

    2010-01-01

    Pears of S. Bartolomeu variety have been used over the years in Portugal to produce a traditional dried pear using the cheapest practice with environmental friendly characteristics: open-sun drying. However, the obvious disadvantages concerning the drying efficiency and safety of the dried product have been an incentive to design or improve solar drying methods as an alternative to the traditional one. The present work has tested three types of drying processes...

  3. Is there a distinct continental slope fauna in the Antarctic?

    Science.gov (United States)

    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

  4. Dry electrodes for electrocardiography

    International Nuclear Information System (INIS)

    Patient biopotentials are usually measured with conventional disposable Ag/AgCl electrodes. These electrodes provide excellent signal quality but are irritating for long-term use. Skin preparation is usually required prior to the application of electrodes such as shaving and cleansing with alcohol. To overcome these difficulties, researchers and caregivers seek alternative electrodes that would be acceptable in clinical and research environments. Dry electrodes that operate without gel, adhesive or even skin preparation have been studied for many decades. They are used in research applications, but they have yet to achieve acceptance for medical use. So far, a complete comparison and evaluation of dry electrodes is not well described in the literature. This work compares dry electrodes for biomedical use and physiological research, and reviews some novel systems developed for cardiac monitoring. Lastly, the paper provides suggestions to develop a dry-electrode-based system for mobile and long-term cardiac monitoring applications. (topical review)

  5. Dry eye syndrome

    Science.gov (United States)

    ... workplace (wind, air conditioning) Sun exposure Smoking or second-hand smoke exposure Cold or allergy medicines Dry eye ... helpful steps include: DO NOT smoke and avoid second-hand smoke, direct wind, and air conditioning. Use a ...

  6. What Is Dry Eye?

    Medline Plus

    Full Text Available ... about eye health and preserving your vision. Privacy Policy Related The link between seasonal allergens and dry ... Academy Financial Relationships with Industry Medical Disclaimer Privacy Policy Terms of Service For Advertisers For Media Ophthalmology ...

  7. Dry Skin (Xerosis)

    Science.gov (United States)

    ... skin may have cracks that resemble a dry lake bed. Inflammation of the areas may lead to ... free creams or ointments Preparations containing alpha-hydroxy acids such as glycolic acid or lactic acid Creams ...

  8. Dry Skin Relief

    Science.gov (United States)

    ... resources Meet our partners Español Donate Diseases and treatments Acne and rosacea Bumps and growths Color problems Contagious skin diseases Cosmetic treatments Dry / sweaty skin Eczema / dermatitis Hair and scalp ...

  9. Freeze drying method

    International Nuclear Information System (INIS)

    The present invention provides methods and apparatus for freeze drying in which a solution, which can be a radioactive salt dissolved within an acid, is frozen into a solid on vertical plates provided within a freeze drying chamber. The solid is sublimated into vapor and condensed in a cold condenser positioned above the freeze drying chamber and connected thereto by a conduit. The vertical positioning of the cold condenser relative to the freeze dryer helps to help prevent substances such as radioactive materials separated from the solution from contaminating the cold condenser. Additionally, the system can be charged with an inert gas to produce a down rush of gas into the freeze drying chamber to also help prevent such substances from contaminating the cold condenser

  10. Dry Mouth (Xerostomia)

    Science.gov (United States)

    ... teeth from decay It prevents infection by controlling bacteria and fungi in the mouth It makes it ... drinks often. Avoid drinks with caffeine, such as coffee, tea, and some sodas. Caffeine can dry out ...

  11. [Little Dry Creek Drainage

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Map of the drainage boundary, direction of flow, canals and ditches, and streets for the drainage study plan and profile for Little Dry Creek sub area in the North...

  12. What Is Dry Eye?

    Medline Plus

    Full Text Available ... close my eyes when I sleep? Feb 10, 2016 Cortisone Shot and Dry Eye Aug 30, 2015 ... Media Ophthalmology Job Center © American Academy of Ophthalmology 2016 Our Sites EyeWiki International Society of Refractive Surgery ...

  13. Eliminating cracking during drying

    OpenAIRE

    Jin, Qiu; Tan, Peng; Schofield, Andrew B.; Xu, Lei

    2013-01-01

    When colloidal suspensions dry, stresses build up and cracks often occur - a phenomenon undesirable for important industries such as paint and ceramics. We demonstrate an effective method which can completely eliminate cracking during drying: by adding emulsion droplets into colloidal suspensions, we can systematically decrease the amount of cracking, and eliminate it completely above a critical droplet concentration. Since the emulsion droplets eventually also evaporate, our technique achiev...

  14. GELATIN DRYING PROCESS

    OpenAIRE

    Silva, E A; I. Neitzel; L.H.M. Silva

    2001-01-01

    In one of the stages of the gelatin production process, a highly concentrated solution of gel is cooled and extruded to form gelatin noodles, which are then laid on a drying belt. Gelatin is a molecular colloid that is not porous under these drying conditions, and as a consequence, water migration occurs solely by diffusive processes. To achieve a commercial standard of dryness, the dependence of the diffusion coefficient as a function of temperature is used. This set of circumstances favors ...

  15. COLOUR DEVELOPMENT ON DRYING

    OpenAIRE

    Roger B Keey

    2005-01-01

    The drying of wet materials induces a number of physico-chemical changes in the product, often reflected in colour. For dried products sold on appearance, like certain grades of wood, the extent of colour development is highly significant in terms of the material’s end-use. Until recently, colour was normally assessed by eye, but the availability of convenient spectrophotometers has provided industrial users with a means of quantitative description of colour. Examples from wood technolo...

  16. Acoustoconvection Drying of Meat

    Science.gov (United States)

    Zhilin, A. A.; Fedorov, A. V.

    2016-03-01

    The dynamics of moisture extraction from meat samples by the acoustoconvection and thermoconvection methods has been investigated. To describe the dynamics of moisture extraction from meat, we propose a simple relaxation model with a relaxation time of 8-10 min in satisfactorily describing experimental data on acoustoconvection drying of meat. For thermoconvection drying the relaxation time is thereby 30 and 45 min for the longitudinal and transverse positions of fibers, respectively.

  17. Evaluation of the biological toxicity of lfuorine in Antarctic krill

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ling; LU Xiaoqi; WANG Zhangmin; QIN Liqiang; LIN Zhiqin; YUAN Linxi; ZHANG Wen; YIN Xuebin

    2014-01-01

    Antarctic krill is a potentially nutritious food source for humans, but lfuorine (F) toxicity is a matter of concern. To evaluate the toxicity of F in Antarctic krill, 30 Wistar rats were divided into three groups with different dietary regimens:a control group, a krill treatment group (150 mg·kg-1 F), and a sodium lfuoride (NaF) treatment group (150 mg·kg-1 F). After three months, F concentrations in feces, plasma, and bone were determined, and the degree of dental and skeletal lfuorosis was assessed. The F concentrations in plasma and bone from the krill treatment group were 0.167 0±0.020 4 mg.L-1 and 2 709.8±301.9 mg·kg-1, respectively, compared with 0.043 8±0.005 5 mg·L-1 and 442.4±60.7 mg·kg-1, respectively, in samples from the control group. Concentrations of F in plasma and bone in the krill treatment group were higher than in the control group, but lower than in the NaF treatment group. The degree of dental lfuorosis in the krill treatment group was moderate, compared with severe in the NaF treatment group and normal in the control group. The degree of skeletal lfuorosis did not change signiifcantly in any group. These results showed that the toxicity of F in Antarctic krill was lower than for an equivalent concentration of F in NaF, but it was toxic for rats consuming krill in large quantities. To conclude, we discuss possible reasons for the reduced toxicity of F in Antarctic krill. The present study provides a direct toxicological reference for the consideration of Antarctic krill for human consumption.

  18. Evidence for widespread endemism among Antarctic micro-organisms

    Science.gov (United States)

    Vyverman, Wim; Verleyen, Elie; Wilmotte, Annick; Hodgson, Dominic A.; Willems, Anne; Peeters, Karolien; Van de Vijver, Bart; De Wever, Aaike; Leliaert, Frederik; Sabbe, Koen

    2010-08-01

    Understanding the enormous diversity of microbes, their multiple roles in the functioning of ecosystems, and their response to large-scale environmental and climatic changes, are at the forefront of the international research agenda. In Antarctica, where terrestrial and lacustrine environments are predominantly microbial realms, an active and growing community of microbial ecologists is probing this diversity and its role in ecosystem processes. In a broader context, this work has the potential to make a significant contribution to the long-standing debate as to whether microbes are fundamentally different from macroorganisms in their biogeography. According to the ubiquity hypothesis, microbial community composition is not constrained by dispersal limitation and is solely the result of species sorting along environmental gradients. However, recent work on several groups of microalgae is challenging this view. Global analyses using morphology-based diatom inventories have demonstrated that, in addition to environmental harshness, geographical isolation underlies the strong latitudinal gradients in local and regional diversity in the Southern hemisphere. Increasing evidence points to a strong regionalization of diatom floras in the Antarctic and sub-Antarctic regions, mirroring the biogeographical regions that have been recognized for macroorganisms. Likewise, the application of molecular-phylogenetic techniques to cultured and uncultured diversity revealed a high number of Antarctic endemics among cyanobacteria and green algae. Calibration of these phylogenies suggests that several clades have an ancient evolutionary history within the Antarctic continent, possibly dating back to 330 Ma. These findings are in line with the current view on the origin of Antarctic terrestrial metazoa, including springtails, chironomids and mites, with most evidence suggesting a long history of geographic isolation on a multi-million year, even pre-Gondwana break-up timescale.

  19. Resonant valley filtering of massive Dirac electrons

    OpenAIRE

    Moldovan, D.; Masir, M. Ramezani; Covaci, L.; Peeters, F. M.

    2013-01-01

    Electrons in graphene, in addition to their spin, have two pseudospin degrees of freedom: sublattice and valley pseudospin. Valleytronics uses the valley degree of freedom as a carrier of information similar to the way spintronics uses electron spin. We show how a double barrier structure consisting of electric and vector potentials can be used to filter massive Dirac electrons based on their valley index. We study the resonant transmission through a finite number of barriers and we obtain th...

  20. At-Sea Distribution and Prey Selection of Antarctic Petrels and Commercial Krill Fisheries.

    Science.gov (United States)

    Descamps, Sébastien; Tarroux, Arnaud; Cherel, Yves; Delord, Karine; Godø, Olaf Rune; Kato, Akiko; Krafft, Bjørn A; Lorentsen, Svein-Håkon; Ropert-Coudert, Yan; Skaret, Georg; Varpe, Øystein

    2016-01-01

    Commercial fisheries may impact marine ecosystems and affect populations of predators like seabirds. In the Southern Ocean, there is an extensive fishery for Antarctic krill Euphausia superba that is projected to increase further. Comparing distribution and prey selection of fishing operations versus predators is needed to predict fishery-related impacts on krill-dependent predators. In this context, it is important to consider not only predators breeding near the fishing grounds but also the ones breeding far away and that disperse during the non-breeding season where they may interact with fisheries. In this study, we first quantified the overlap between the distribution of the Antarctic krill fisheries and the distribution of a krill dependent seabird, the Antarctic petrel Thalassoica antarctica, during both the breeding and non-breeding season. We tracked birds from the world biggest Antarctic petrel colony (Svarthamaren, Dronning Maud Land), located >1000 km from the main fishing areas, during three consecutive seasons. The overall spatial overlap between krill fisheries and Antarctic petrels was limited but varied greatly among and within years, and was high in some periods during the non-breeding season. In a second step, we described the length frequency distribution of Antarctic krill consumed by Antarctic petrels, and compared this with results from fisheries, as well as from diet studies in other krill predators. Krill taken by Antarctic petrels did not differ in size from that taken by trawls or from krill taken by most Antarctic krill predators. Selectivity for specific Antarctic krill stages seems generally low in Antarctic predators. Overall, our results show that competition between Antarctic petrels and krill fisheries is currently likely negligible. However, if krill fisheries are to increase in the future, competition with the Antarctic petrel may occur, even with birds breeding thousands of kilometers away. PMID:27533327

  1. At-Sea Distribution and Prey Selection of Antarctic Petrels and Commercial Krill Fisheries

    Science.gov (United States)

    Descamps, Sébastien; Tarroux, Arnaud; Cherel, Yves; Delord, Karine; Godø, Olaf Rune; Kato, Akiko; Krafft, Bjørn A.; Lorentsen, Svein-Håkon; Ropert-Coudert, Yan; Skaret, Georg; Varpe, Øystein

    2016-01-01

    Commercial fisheries may impact marine ecosystems and affect populations of predators like seabirds. In the Southern Ocean, there is an extensive fishery for Antarctic krill Euphausia superba that is projected to increase further. Comparing distribution and prey selection of fishing operations versus predators is needed to predict fishery-related impacts on krill-dependent predators. In this context, it is important to consider not only predators breeding near the fishing grounds but also the ones breeding far away and that disperse during the non-breeding season where they may interact with fisheries. In this study, we first quantified the overlap between the distribution of the Antarctic krill fisheries and the distribution of a krill dependent seabird, the Antarctic petrel Thalassoica antarctica, during both the breeding and non-breeding season. We tracked birds from the world biggest Antarctic petrel colony (Svarthamaren, Dronning Maud Land), located >1000 km from the main fishing areas, during three consecutive seasons. The overall spatial overlap between krill fisheries and Antarctic petrels was limited but varied greatly among and within years, and was high in some periods during the non-breeding season. In a second step, we described the length frequency distribution of Antarctic krill consumed by Antarctic petrels, and compared this with results from fisheries, as well as from diet studies in other krill predators. Krill taken by Antarctic petrels did not differ in size from that taken by trawls or from krill taken by most Antarctic krill predators. Selectivity for specific Antarctic krill stages seems generally low in Antarctic predators. Overall, our results show that competition between Antarctic petrels and krill fisheries is currently likely negligible. However, if krill fisheries are to increase in the future, competition with the Antarctic petrel may occur, even with birds breeding thousands of kilometers away. PMID:27533327

  2. RESEARCH REGARDING THE MELLIFEROUS CHARACTHERISTICS OF LABIATES FROM XEROPHILE MEADOWS FROM DANUBE VALLEY

    OpenAIRE

    NICOLETA ION

    2013-01-01

    The xerophile meadows in the Danube Valley are dry meadows, located at a great distance from the Danube and with underground waters at greater depth. Their floral composition is characterized by a small number of species pertaining to both mezoxerophiles and to xerophiles, yet the highest percentage is covered by xerophile species, which are characterized by their small foliage surface, the very narrow and tough limb, and acute porosity etc.In the floral composition of these species, the gram...

  3. Autochthonous "Bjelovars dried cheese"

    Directory of Open Access Journals (Sweden)

    Slavko Kirin

    2006-12-01

    Full Text Available «Dried cheese» is in autochthonous group of Bjelovar region cheeses which is still produced in rural domestic scale. The name of cheese originates from production procedure - drying for longer or shorter period in airy place after which the cheese is smoked, or is smoked only without drying. This type of cheese is produced in whole central region of Croatia which includes Međimurje, Podravina, Bilogora; Moslavina, Posavina and region around the capital. The aim of this paper is to describe and determine sensory, chemical and microbiological composition to determine its characteristics and production standards. As standards for sensory properties following characteristics can be used: a Outer shape: dimensions: diameter: 140-145 mm, height: 58-61 mm, mass: 700-750 g, equal, rounded shape, smooth skin, equal colour; b Consistency: easily cut, elastic, soft; c Cut: nicely combined white body, few improper holes of equal size; d Odour: pleasant milky acid odour, fairly smoky; e Taste: Fairly milky acidic taste, medium salty, fairly smoky taste. Depending on fat in dry matter content and water content in non fat dry matter, analyzed samples can be characterized as quarter fat, soft and semidry cheese. Higher acidity and saltiness was determined in some samples, microbiological analyses has shown that the most common contaminants are yeasts and moulds.

  4. Unmanned aerial optical systems for spatial monitoring of Antarctic mosses

    Science.gov (United States)

    Lucieer, Arko; Turner, Darren; Veness, Tony; Malenovsky, Zbynek; Harwin, Stephen; Wallace, Luke; Kelcey, Josh; Robinson, Sharon

    2013-04-01

    The Antarctic continent has experienced major changes in temperature, wind speed and stratospheric ozone levels during the last 50 years. In a manner similar to tree rings, old growth shoots of Antarctic mosses, the only plants on the continent, also preserve a climate record of their surrounding environment. This makes them an ideal bio-indicator of the Antarctic climate change. Spatially extensive ground sampling of mosses is laborious and time limited due to the short Antarctic growing season. Obviously, there is a need for an efficient method to monitor spatially climate change induced stress of the Antarctic moss flora. Cloudy weather and high spatial fragmentation of the moss turfs makes satellite imagery unsuitable for this task. Unmanned aerial systems (UAS), flying at low altitudes and collecting image data even under a full overcast, can, however, overcome the insufficiency of satellite remote sensing. We, therefore, developed scientific UAS, consisting of a remote-controlled micro-copter carrying on-board different remote sensing optical sensors, tailored to perform fast and cost-effective mapping of Antarctic flora at ultra-high spatial resolution (1-10 cm depending on flight altitude). A single lens reflex (SLR) camera carried by UAS acquires multi-view aerial photography, which processed by the Structure from Motion computer vision algorithm provides an accurate three-dimensional digital surface model (DSM) at ultra-high spatial resolution. DSM is the key input parameter for modelling a local seasonal snowmelt run-off, which provides mosses with the vital water supply. A lightweight multispectral camera on-board of UVS is collecting images of six selected spectral wavebands with the full-width-half-maximum (FWHM) of 10 nm. The spectral bands can be used to compute various vegetation optical indices, e.g. Difference Vegetation Index (NDVI) or Photochemical Reflectance Index (PRI), assessing the actual physiological state of polar vegetation. Recently

  5. Agricultural water and energy use in the Senegal River Valley

    Science.gov (United States)

    Masiyandima, M. C.; Sow, A.

    2015-12-01

    Assessment of the productivity of irrigation water is important measuring the performance of irrigation schemes especially in water scarce areas. Equally important for performance is the energy cost of providing water for irrigation. Sahel irrigation schemes are dependent on pumping water from rivers into a network of gravity operated channels. In the Senegal River valley in Senegal the cost of pumping water and for irrigation has been estimated to be 20-25% of total rice production costs. Irrigation schemes in the valley are characterized by low water productivity. We analysed rice production, irrigation water use and energy use for supplying irrigation water at Pont Gendarme, Ndiawar and Ngallenka MCA irrigation schemes in the Senegal River valley. For the 2013 rainfall season the mean yield ranged between 6 and 8t ha-1. Dry season yield ranged between 1.7 and 6.8t ha-1. Energy use for irrigation in the Ndiawar irrigation scheme was 8kg MJ-1 and 6.4kg MJ-1 in the 2013 and 2014 rainfall seasons respectively. In 2014 (rainfall season) energy productivity of irrigation water was 8.5, 8.0 and 16.4 kg MJ-1 at Ngallenka MCA, Ndiawar and Pont Gendarme respectively. Dry season (2014) energy productivity at Ndiawar and Pont Gendarme was 3.4 and 11.2kg MJ-1 respectively. Productivity of irrigation water was similar for all schemes (0.37kg m-3 at Pont Gendarme, 0.42kg m-3 at Ngallenka MCA, and 0.41kg m-3 Ndiawar). Energy use for the supply of irrigation water in the rainfall season ranged from 403 to 1,002MJ ha-1. Dry season irrigation energy use was 589MJ ha-1 Pont Gendarme and 331MJ ha-1 at Ndiawar. Reducing water use in these schemes through better water management will result in lower production costs and increased margins for the farmers. The observations from 2013 - 2014 highlight the importance of using both water and energy productivity to assess performance of irrigation schemes.

  6. GELATIN DRYING PROCESS

    Directory of Open Access Journals (Sweden)

    E.A. Silva

    2001-12-01

    Full Text Available In one of the stages of the gelatin production process, a highly concentrated solution of gel is cooled and extruded to form gelatin noodles, which are then laid on a drying belt. Gelatin is a molecular colloid that is not porous under these drying conditions, and as a consequence, water migration occurs solely by diffusive processes. To achieve a commercial standard of dryness, the dependence of the diffusion coefficient as a function of temperature is used. This set of circumstances favors the appearance of sharp concentration gradients inside the gel. In a numerical simulation of the drying process these characteristics create difficult conditions for use of the traditional methods for solution of time-dependent partial differential equation models. This paper evaluates an implementation of the boundary element method to determine surface conditions of the gelatin particle.

  7. Drying of Concrete

    DEFF Research Database (Denmark)

    Hansen, Kurt Kielsgaard; Geiker, Mette Rica; Nygaard, Peter Vagn; Kjeldsen, Ane Mette

    Estimated and measured relative humidity (RH) change during drying are compared for two concretes, 1: w/c=0.46 and 2: w/(c+0.5fa+2sf)=0.50. The estimations were undertaken by means of the Swedish program TorkaS 1.0. Measurements were performed by RH-sensors type Humi-Guard. Drying of 150 mm thick...... samples from sides at 60% RH and 22 °C took place from 4 to 56 days after casting. At the end of the drying period the measured RH was about 4% lower than the estimated RH at 1/5th depth from the exposed surface for both concretes. In the middle of the samples, the measured RH of concretes 1 and 2 were 2...

  8. Magnetically responsive dry fluids.

    Science.gov (United States)

    Sousa, Filipa L; Bustamante, Rodney; Millán, Angel; Palacio, Fernando; Trindade, Tito; Silva, Nuno J O

    2013-08-21

    Ferrofluids and dry magnetic particles are two separate classes of magnetic materials with specific niche applications, mainly due to their distinct viscosity and interparticle distances. For practical applications, the stability of these two properties is highly desirable but hard to achieve. Conceptually, a possible solution to this problem would be encapsulating the magnetic particles but keeping them free to rotate inside a capsule with constant interparticle distances and thus shielded from changes in the viscosity of the surrounding media. Here we present an example of such materials by the encapsulation of magnetic ferrofluids into highly hydrophobic silica, leading to the formation of dry ferrofluids, i.e., a material behaving macroscopically as a dry powder but locally as a ferrofluid where magnetic nanoparticles are free to rotate in the liquid. PMID:23831769

  9. Talc as a Substitute for Dry Lubricant (an Overview)

    Science.gov (United States)

    Abdulkareem, Suleiman; Orkuma, Gideon I.; Apasi, Adaokoma A.

    2011-01-01

    All metal surfaces, irrespective of their surface integrity, appear as a series of peaks and valleys under close examination. The objective of lubrication is to separate these peaks and valleys so that contact is avoided in metal to metal, hence greatly reduce or eliminate wear. A lubricant may be gas, liquid, semi-solid, or solid that permits free action of mechanical devices and prevents damage by abrasion and seizing of metal or other components through unequal expansion caused by heat. Among the solid (dry) lubricants includes: graphite, glass, boron nitride, polytetrafluoroethene (PTFE-Teflon), molybdenum disulfide, tungsten disulfide, lime, talc, etc. Solid (dry) lubricants differ significantly from liquid lubricants, in that liquid lubricants reduce friction due to their fluidity and viscosity. However, solid lubricants have neither of these properties but they are still capable of reducing friction and wear in metal. In this work, the study of the property characteristics of talc as a substitute for graphite in dry lubrication (an overview) was carried out and reported in this paper.

  10. Relative Changes in KrillAbundance Inferred from Antarctic Fur Seal

    OpenAIRE

    Huang, T.; Sun, L; Stark, John M.; Wang, Y.; Cheng, Z.; Yang, Q.; Sun, S.

    2011-01-01

    Antarctic krill Euphausia superba is a predominant species in the Southern Ocean, it is very sensitive to climate change, and it supports large stocks of fishes, seabirds, seals and whales in Antarctic marine ecosystems. Modern krill stocks have been estimated directly by net hauls and acoustic surveys; the historical krill density especially the long-term one in the Southern Ocean, however, is unknown. Here we inferred the relative krill population changes along the West Antarctic Peninsula ...

  11. Mitochondrial plasticity in response to changing abiotic factors in Antarctic fish and cephalopods

    OpenAIRE

    Strobel, Anneli

    2013-01-01

    Antarctic species possess very low metabolic rates and poor capacities to change their physiological state, thus making them extremely vulnerable to changing environmental conditions. Mitochondria are a key element in shaping whole organism energy turnover and functional capacity. In my study, the effects of rising temperature and increased seawater PCO2 on the energy metabolism were compared between various nototheniids from sub-Antarctic and cold-temperate and Antarctic waters, and between ...

  12. Do Antarctic fish like it hot? What energy allocation can tell us about distribution shifts

    OpenAIRE

    Sandersfeld, Tina; Davison, William; Lamare, Miles D.; Richter, Claudio; Knust, Rainer

    2014-01-01

    Despite evidence for distribution shifts of single species and ecosystem changes as a reaction to global warming, little is known about the underlying processes. As a consequence of warming waters in the Southern Ocean, shifts in species distribution are expected with sub-Antarctic species migrating southward to high-Antarctic waters, while species from temperate regions might intrude sub-Antarctic areas. Species distribution and abundance are driven by reproduction and somatic growth, which ...

  13. Sensitivity of Antarctic fish to ocean warming - an energy budget approach

    OpenAIRE

    Sandersfeld, Tina

    2015-01-01

    Like the Arctic, the Antarctic region hosts some of the hot spots of climatic change. At the western Antarctic Peninsula, alterations of air and water temperature, pH, salinity and sea-ice regime were reported and associated shifts in species abundance and changes in food web structure have already become evident. In contrast, for most high-Antarctic regions, no climate related changes have yet been found. However, future temperature increases are also projected for these areas. Ocean warming...

  14. A physically-based statistical forecast model for the middle-lower reaches of the Yangtze River Valley summer rainfall

    Institute of Scientific and Technical Information of China (English)

    FAN Ke; WANG HuiJun; CHOI YoungJean

    2008-01-01

    A new approach to forecast the middle-lower reaches of the Yangtze River Valley summer rainfall in June-August (JJA) is proposed in this paper. The year-to-year increment of the middle-lower reaches of the Yangtze River Valley is forecasted and hence the summer precipitation could be predicted. In this paper, DY is defined as the difference of a variable between the current year and the preceding year (year-to-year increment). YR denotes the seasonal mean precipitation rate of the middle-lower reaches of the Yangtze River Valley summer rainfall. After analyzing the atmospheric circulation anomalies in winter and spring that were associated with the DY of YR, six key predictors for the DY of YR have been identified. Then the forecast model for the DY of YR is established by using the multi-linear regression method. The predictors for the DY of YR are Antarctic Oscillation, the meridional wind shear between 850hPa and 200hPa over the Indo-Australian region, and so on. The prediction model shows a high skill for the hindcast during 1997-2006, with the average relative root mean square error is at 18%. The model can even reproduce the upward and downward trends of YR during 1984-1998 and 1998-2006. Considering that the current operational forecast models of the summer precipitation over the China region have the average forecast scores at 60%-70% and that the prediction skill for the middle-lower reaches of Yangtze River Valley summer precipitation remains quite limited up to now, thus this new approach to predict the year-to-year increment of the summer precipitation over the Yangtze River Valley (and hence the summer precipitation itself) has the potential to significantly increase the operational forecast skill of the summer precipitation.

  15. Valley-dependent band structure and valley polarization in periodically modulated graphene

    Science.gov (United States)

    Lu, Wei-Tao

    2016-08-01

    The valley-dependent energy band and transport property of graphene under a periodic magnetic-strained field are studied, where the time-reversal symmetry is broken and the valley degeneracy is lifted. The considered superlattice is composed of two different barriers, providing more degrees of freedom for engineering the electronic structure. The electrons near the K and K' valleys are dominated by different effective superlattices. It is found that the energy bands for both valleys are symmetric with respect to ky=-(AM+ξ AS) /4 under the symmetric superlattices. More finite-energy Dirac points, more prominent collimation behavior, and new crossing points are found for K' valley. The degenerate miniband near the K valley splits into two subminibands and produces a new band gap under the asymmetric superlattices. The velocity for the K' valley is greatly renormalized compared with the K valley, and so we can achieve a finite velocity for the K valley while the velocity for the K' valley is zero. Especially, the miniband and band gap could be manipulated independently, leading to an increase of the conductance. The characteristics of the band structure are reflected in the transmission spectra. The Dirac points and the crossing points appear as pronounced peaks in transmission. A remarkable valley polarization is obtained which is robust to the disorder and can be controlled by the strain, the period, and the voltage.

  16. The South Atlantic in the Fine-Resolution Antarctic Model

    Directory of Open Access Journals (Sweden)

    D. P. Stevens

    Full Text Available The geographical area covered by the Fine-Resolution Antarctic Model (FRAM includes that part of the South Atlantic south of 24°S. A description of the dynamics and thermodynamics of this region of the model is presented. Both the mean and eddy fields in the model are in good agreement with reality, although the magnitude of the transients is somewhat reduced. The heat flux is northward and in broad agreement with many other estimates. Agulhas eddies are formed by the model and propagate westward into the Atlantic providing a mechanism for fluxing heat from the Indian Ocean. The confluence of the Brazil and Falkland currents produces a strong front and a large amount of mesoscale activity. In the less stratified regions to the south, topographic steering of the Antarctic circumpolar current is important.

  17. On the manoeuvering simulation of an Antarctic hovercraft

    Science.gov (United States)

    Murao, R.; Nojiri, T.

    Since 1981 an experimental hovercraft for the Antarctic has been tested in Japan's Antarctic station Syowa. During tests on the ice field near Syowa station, it was experienced that the yaw response of this craft is very sensitive to certain ice conditions. In this report, we deal with course keeping of the craft in relative crosswinds and with the maneuvering simulation while turning. Maneuvering at large yaw angle is required to generate the effective centripetal force in turning. The trajectories based on pulse steering are obtained. The course stability is very dependent upon the friction between skirts and ground, and generally not good on smooth flat ice. It is shown, however, that the rudder automatic control provides good course stability independent of ice conditions. The trajectories obtained from the simulation show that the use of a combination of rudder control and puff ports produces quick turning.

  18. The 1988 Antarctic ozone depletion - Comparison with previous year depletions

    Science.gov (United States)

    Schoeberl, Mark R.; Stolarski, Richard S.; Krueger, Arlin J.

    1989-01-01

    The 1988 spring Antarctic ozone depletion was observed by TOMS to be substantially smaller than in recent years. The minimum polar total ozone values declined only 15 percent during September 1988, compared to nearly 50 percent during September 1987. At southern midlatitudes, exceptionally high total ozone values were recorded beginning in July 1988. The total integrated southern hemispheric ozone increased rapidly during the Austral spring, approaching 1980 levels during October. The high midlatitude total ozone values were associated with a substantial increase in eddy activity as indicated by the standard deviation in total ozone in the zonal band 30-60 deg S. Mechanisms through which the increased midlatitude eddy activity could disrupt the formation of the Antarctic ozone hole are briefly discussed.

  19. Ozone depletion - Ultraviolet radiation and phytoplankton biology in Antarctic waters

    Science.gov (United States)

    Smith, R. C.; Prezelin, B. B.; Baker, K. S.; Bidigare, R. R.; Boucher, N. P.; Coley, T.; Karentz, D.; Macintyre, S.; Matlick, H. A.; Menzies, D.

    1992-01-01

    The near-50-percent thinning of the stratospheric ozone layer over the Antarctic, with increased passage of mid-UV radiation to the surface of the Southern Ocean, has prompted concern over possible radiation damage to the near-surface phytoplankton communities that are the bases of Antarctic marine ecosystems. As the ozone layer thinned, a 6-week study of the marginal ice zone of the Bellingshousen Sea in the austral spring of 1990 noted sea-surface and depth-dependent ratios of mid-UV irradiance to total irradiance increased, and mid-UV inhibition of photosynthesis increased. A 6-12 percent reduction in primary production associated with ozone depletion was estimated to have occurred over the course of the present study.

  20. Antarctic springtime ozone depletion computed from temperature observations

    Science.gov (United States)

    Rosenfield, Joan E.; Schoeberl, Mark R.; Newman, Paul A.

    1988-01-01

    An observationally based, mechanistic dynamical model is used to simulate the decline of total ozone during September and October for the years 1979 through 1986. Vertical velocities derived from observed stratospheric temperature changes and computed radiative heating rates are used to advect an ozone mixing ratio profile during the Antarctic spring period. An early August 1982 Syowa balloonsonde ozone profile is used to initialize the computations. The model reasonably simulates the September and October changes in total ozone, considering the uncertainties in the observed data and the radiative heating. The simulated decline is found to be very sensitive to the choice of initial ozone profile and to small changes in the radiative heating. The results of this study suggest that the dynamical hypothesis of the Antarctic ozone depletion is both quantitatively credible and consistent with the observed temperature changes.

  1. Antarctic sea ice: Its development and basic properties

    International Nuclear Information System (INIS)

    The author reports investigations on sea ice properties carried out during a number of expeditions into the Weddell Sea, Antarctica. The results provide important baseline data, against which possible changes in the Antarctic sea ice cover as induced by climatic changes can be compared. This paper concentrates on results dealing with the textural properties and the ice thickness distributions of Antarctic sea ice. In addition, the author looks at the contribution of meteoric ice (snow ice) to the sea ice cover by means of δ18O measurements. While changes in extent and thickness are to be expected as a result of possible climatic warming, they propose that the amount of snow ice will serve as an additional indicator of such changes

  2. Results and perspectives of tectonomagnetic investigations in the Western Antarctic

    Directory of Open Access Journals (Sweden)

    Ihor O. Chobotok

    2009-06-01

    Full Text Available The results of long-term (1998-2005 yrs. tectonomagnetic investigations in the Western Antarctic near the location
    of Ukrainian Antarctic Station «Academic Vernadsky» are reviewed. The peculiarities of the Earth’s
    anomalous magnetic field and its dynamic temporal variations (tectonomagnetic anomalies were studied using
    the newly founded tectonomagnetic polygon. Near the Argentine Archipelago intensive tectonomagnetic effects
    up to -2.8 nT/year were determined. Their spatial-temporal structure agrees with tectonic structure elements. We
    suggest that the nature of such effects is caused by a piezomagnetic effect under the influence of stretching tectonic
    forces (few bars per year in sub-latitudinal direction. Perspectives of tectonomagnetic investigations in the
    region are discussed.

  3. Enjoy Samba Carnival in Happy Valley

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    On July3,the Yanjing Beer 2009 Beijing Happy Valley Mayan Carnival was grandly opened.The carnival will last for almost two months until August 30.With support from Yanjing Beer,Happy Valley is able to provide an authentic Brazilian festival including hot music and dancing,

  4. Vernal Pool Distribution - Central Valley, 2005 [ds650

    Data.gov (United States)

    California Department of Resources — "Great Valley Vernal Pool Distribution", originally mapped by Bob Holland, 2005. This dataset contains vernal pool areas mapped over Califorina's Central Valley,...

  5. Remote Antarctic feeding ground important for east Australian humpback whales

    OpenAIRE

    Constantine, R.; Steel, D.; Allen, J.; Anderson, M; Andrews, O.; Baker, C.; Beeman, P.; Burns, D.; Charrassin, J. B.; Childerhouse, S.; Double, M; Ensor, P.; Franklin, T; Franklin, W; Gales, N.

    2014-01-01

    Understanding the dynamics of population recovery is particularly complex when an organism has multiple, remote breeding and feeding grounds separated by one of the longest known migration routes. This study reports on the most comprehensive assessment of humpback whale (Megaptera novaeangliae) movements between remote Antarctic waters south of New Zealand and east Australia (EA), and the migratory corridors and breeding grounds of Australia and Oceania. A total of 112 individual whales were ...

  6. Cyclone formation and development in the Antarctic Prydz Bay

    Institute of Scientific and Technical Information of China (English)

    解思梅; 梅山; 刘克威; 魏立新

    2002-01-01

    Using meteorological data of field observation in 1990~ 2000 , especially polar orbit highresolution NOAA satellite cloud maps received from the Antarctic expedition vessel since 1997, the formation and development of the Prydz Bay cyclone are studied in this paper. Some new viewpoints are suggested such as: when surround-polar cyclone enters the Prydz Bay, it can also intensify and develop in summer; cyclone can also develop in the easterlies in this bay. These view points revise old uncomplete view point that the Prydz Bay is a burial ground of cyclone, and also further consummate formation-development theory of surround-cyclone in the Antarctic westerlies and cyclone in the Antarctic easterlies. In this paper, the mechanism of ice-air-sea interaction in the Prydz Bay is studied, and the physical process of cyclone formation-development is explained. By use of wholly dynamic transportation method, an energy exchange case of a cyclone, which explosively developed after entering the Prydz Bay, is calculated. In the open water area, momentum flux is - 2.205 N/m2, sensible heat flux is 486.69 W/m2, and latent heat flux is 261.84 W/m2. It is larger than values of westerlies burst over the Pacific. The heat transferred from ocean to atmosphere in form of sensible and latent heat promotes cyclone development rapidly. In this case wind force was as strong as 12 grade, with 10 minutes average wind speed of 38 m/s, and instantaneous wind speed of 100 m/s which broke the wind speed record of 96 m/s in the Antarctic (Wendler and Kodama).

  7. Obliquity-paced Pliocene West Antarctic ice sheet oscillations

    Science.gov (United States)

    Naish, T.; Powell, R.; Levy, R.; Wilson, G.; Scherer, R.; Talarico, F.; Krissek, L.; Niessen, F.; Pompilio, M.; Wilson, T.; Carter, L.; DeConto, R.; Huybers, P.; McKay, R.; Pollard, D.; Ross, J.; Winter, D.; Barrett, P.; Browne, G.; Cody, R.; Cowan, E.; Crampton, J.; Dunbar, G.; Dunbar, N.; Florindo, F.; Gebhardt, C.; Graham, I.; Hannah, M.; Hansaraj, D.; Harwood, D.; Helling, D.; Henrys, S.; Hinnov, L.; Kuhn, G.; Kyle, P.; Laufer, A.; Maffioli, P.; Magens, D.; Mandernack, K.; McIntosh, W.; Millan, C.; Morin, R.; Ohneiser, C.; Paulsen, T.; Persico, D.; Raine, I.; Reed, J.; Riesselman, C.; Sagnotti, L.; Schmitt, D.; Sjunneskog, C.; Strong, P.; Taviani, M.; Vogel, S.; Wilch, T.; Williams, T.

    2009-01-01

    Thirty years after oxygen isotope records from microfossils deposited in ocean sediments confirmed the hypothesis that variations in the Earth's orbital geometry control the ice ages, fundamental questions remain over the response of the Antarctic ice sheets to orbital cycles. Furthermore, an understanding of the behaviour of the marine-based West Antarctic ice sheet (WAIS) during the 'warmer-than-present' early-Pliocene epoch (???5-3 Myr ago) is needed to better constrain the possible range of ice-sheet behaviour in the context of future global warming. Here we present a marine glacial record from the upper 600 m of the AND-1B sediment core recovered from beneath the northwest part of the Ross ice shelf by the ANDRILL programme and demonstrate well-dated, ???40-kyr cyclic variations in ice-sheet extent linked to cycles in insolation influenced by changes in the Earth's axial tilt (obliquity) during the Pliocene. Our data provide direct evidence for orbitally induced oscillations in the WAIS, which periodically collapsed, resulting in a switch from grounded ice, or ice shelves, to open waters in the Ross embayment when planetary temperatures were up to ???3??C warmer than today and atmospheric CO 2 concentration was as high as ???400 p.p.m.v. (refs 5, 6). The evidence is consistent with a new ice-sheet/ice-shelf model that simulates fluctuations in Antarctic ice volume of up to +7 m in equivalent sea level associated with the loss of the WAIS and up to +3 m in equivalent sea level from the East Antarctic ice sheet, in response to ocean-induced melting paced by obliquity. During interglacial times, diatomaceous sediments indicate high surface-water productivity, minimal summer sea ice and air temperatures above freezing, suggesting an additional influence of surface melt under conditions of elevated CO2. ??2009 Macmillan Publishers Limited. All rights reserved.

  8. Natural thermoluminescence of Antarctic meteorites and related studies

    Science.gov (United States)

    Benoit, Paul H.; Sears, Derek W. G.

    1998-01-01

    The natural thermoluminescence (TL) laboratory's primary purpose is to provide data on newly recovered Antarctic meteorites that can be included in discovery announcements and to investigate the scientific implications of the data. Natural TL levels of meteorites are indicators of recent thermal history and terrestrial history, and the data can be used to study the orbital/radiation history of groups of meteorites (e.g., H chondrites) or to study the processes leading to the concentration of meteorites at certain sites in Antarctica. An important application of these data is the identification of fragments, or "pairs" of meteorites produced during atmospheric passage or during terrestrial weathering. Thermoluminescence data are particularly useful for pairing within the most common meteorite classes, which typically exhibit very limited petrographic and chemical diversity. Although not originally part of the laboratory's objectives, TL data are also useful in the identification and classification of petrographically or mineralogically unusual meteorites, including unequilibrated ordinary chondrites and some basaltic achondrites. In support of its primary mission, the laboratory also engages in TL studies of modern falls, finds from hot deserts, and terrestrial analogs and conducts detailed studies of the TL properties of certain classes of meteorites. These studies include the measurement of TL profiles in meteorites, the determination of TL levels of finds from the Sahara and the Nullarbor region of Australia, and comparison of TL data to other indicators of irradiation or terrestrial history, such as cosmogenic noble gas and radionuclide abundances. Our current work can be divided into five subcategories, (a) TL survey of Antarctic meteorites, (b) pairing and field relations of Antarctic meteorites, (c) characterization of TL systematics of meteorites, (d) comparison of natural TL and other terrestrial age indicators for Antarctic meteorites, and for meteorites

  9. Testing olfactory foraging strategies in an Antarctic seabird assemblage

    OpenAIRE

    Nevitt, G A; Reid, K; Trathan, P.

    2004-01-01

    Procellariiform seabirds (petrels, albatrosses and shearwaters) forage over thousands of square kilometres for patchily distributed prey resources. While these birds are known for their large olfactory bulbs and excellent sense of smell, how they use odour cues to locate prey patches in the vast ocean is not well understood. Here, we investigate species-specific responses to 3-methyl pyrazine in a sub-Antarctic species assemblage near South Georgia Island (54degrees00' S, 36degrees00' W). Pyr...

  10. Ecological and Pharmacological Activities of Antarctic Marine Natural Products.

    Science.gov (United States)

    Avila, Conxita

    2016-06-01

    Antarctic benthic communities are regulated by abundant interactions of different types among organisms, such as predation, competition, etc. Predators are usually sea stars, with omnivorous habits, as well as other invertebrates. Against this strong predation pressure, many organisms have developed all sorts of defensive strategies, including chemical defenses. Natural products are thus quite common in Antarctic organisms with an important ecological and pharmacological potential. In this paper, the chemical defenses of the Antarctic organisms studied during the ECOQUIM and ACTIQUIM projects, as well as their pharmacological potential, are reviewed. For the ecological defenses, predation against the sea star Odontaster validus is analyzed and evaluated along depth gradients as well as considering the lifestyle of the organisms. For the pharmacological activity, the anticancer, anti-inflammatory, and antibacterial activities tested are evaluated here. Very often, only crude extracts or fractions have been tested so far, and therefore, the natural products responsible for such activities remain yet to be identified. Even if the sampling efforts are not uniform along depth, most ecologically active organisms are found between 200 and 500 m depth. Also, from the samples studied, about four times more sessile organisms possess chemical defenses against the sea star than the vagile ones; these represent 50 % of sessile organisms and 35 % of the vagile ones, out of the total tested, being active. Pharmacological activity has not been tested uniformly in all groups, but the results show that relevant activity is found in different phyla, especially in Porifera, Cnidaria, Bryozoa, and Tunicata, but also in others. No relationship between depth and pharmacological activity can be established with the samples tested so far. More studies are needed in order to better understand the ecological relationships among Antarctic invertebrates mediated by natural products and

  11. Atmospheric near surface nitrate at coastal Antarctic sites

    OpenAIRE

    D. Wagenbach; Legrand, M; Fischer, H.; Pichlmayer, F.; E. W. Wolff

    1998-01-01

    Records of atmospheric nitrate were obtained by year-round aerosol sampling at Neumayer and Dumont D'Urville stations, located in the Atlantic and Pacific sector of coastal Antarctica, respectively. Where possible, evaluation of the nitrate records is mainly based on concurrently measured radioisotopes (10Be, 7Be, 210Pb) as well as δ15N in nitrate nitrogen. Observations made at these (and two other coastal Antarctic sites [Savoie et al., 1993]) reveal a uniform nitrate background near 10 ng m...

  12. Ultraviolet radiation response of two heterotropy Antarctic marine bacterial

    International Nuclear Information System (INIS)

    Two Antarctic marine bacterial strains, were exposed to different irradiance of ultraviolet (UV) solar radiation using several experimental protocols and interferential filters. Results showed that both, UV-A and UV-B radiation produce deleterious effects on two tested bacterial strains. The mortality values under UVB treatments were higher than those observed under UVA treatments. UVvi strain proved to be more resistant to UV radiation than the UVps strain. (author)

  13. Antarctic sea ice losses drive gains in benthic carbon drawdown.

    Science.gov (United States)

    Barnes, D K A

    2015-09-21

    Climate forcing of sea-ice losses from the Arctic and West Antarctic are blueing the poles. These losses are accelerating, reducing Earth's albedo and increasing heat absorption. Subarctic forest (area expansion and increased growth) and ice-shelf losses (resulting in new phytoplankton blooms which are eaten by benthos) are the only significant described negative feedbacks acting to counteract the effects of increasing CO2 on a warming planet, together accounting for uptake of ∼10(7) tonnes of carbon per year. Most sea-ice loss to date has occurred over polar continental shelves, which are richly, but patchily, colonised by benthic animals. Most polar benthos feeds on microscopic algae (phytoplankton), which has shown increased blooms coincident with sea-ice losses. Here, growth responses of Antarctic shelf benthos to sea-ice losses and phytoplankton increases were investigated. Analysis of two decades of benthic collections showed strong increases in annual production of shelf seabed carbon in West Antarctic bryozoans. These were calculated to have nearly doubled to >2x10(5) tonnes of carbon per year since the 1980s. Annual production of bryozoans is median within wider Antarctic benthos, so upscaling to include other benthos (combined study species typically constitute ∼3% benthic biomass) suggests an increased drawdown of ∼2.9x10(6) tonnes of carbon per year. This drawdown could become sequestration because polar continental shelves are typically deeper than most modern iceberg scouring, bacterial breakdown rates are slow, and benthos is easily buried. To date, most sea-ice losses have been Arctic, so, if hyperboreal benthos shows a similar increase in drawdown, polar continental shelves would represent Earth's largest negative feedback to climate change. PMID:26394097

  14. Antarctic Ice Sheet and Radar Altimetry: A Review

    OpenAIRE

    Frédérique Rémy; Soazig Parouty

    2009-01-01

    International audience Altimetry is probably one of the most powerful tools for ice sheet observation. Our vision of the Antarctic ice sheet has been deeply transformed since the launch of the ERS1 satellite in 1991. With the launch of ERS2 and Envisat, the series of altimetric observations now provides 19 years of continuous and homogeneous observations that allow monitoring of the shape and volume of ice sheets. The topography deduced from altimetry is one of the relevant parameters reve...

  15. The Antarctic - the wild card in the global climate

    International Nuclear Information System (INIS)

    The overview gives an account of studies of snowfall, ice melting and formation and water flow patterns in the Antarctic during the present global warming period. It also gives a survey of the ice area in the region. The sea water warming is dramatic and a large floating glacier seems to be decomposing which is disrupting the oceanographic and ecological relations in the region and globally and is significantly influencing the global climate

  16. Blue and fin whale acoustics and ecology off Antarctic Peninsula

    OpenAIRE

    Sirovic, Ana

    2006-01-01

    Blue (Balaenoptera musculus) and fin whales (B. physalus) in the Southern Ocean were subjects of extensive whaling industry during the twentieth century. Their current population numbers remain low, making population monitoring using traditional visual surveys difficult. Both blue and fin whales produce low frequency, regularly repeated calls and are suitable for acoustic monitoring. Eight, continuously recording acoustic recorders were deployed off the Western Antarctic Peninsula (WAP) betwe...

  17. Is the species flock concept operational? The Antarctic Shelf case

    OpenAIRE

    Guillaume Lecointre; Nadia Améziane; Marie-Catherine Boisselier; Céline Bonillo; Frédéric Busson; Romain Causse; Anne Chenuil; Arnaud Couloux; Jean-Pierre Coutanceau; Corinne Cruaud; Cédric d'Udekem d'Acoz; Chantal De Ridder; Gael Denys; Agnès Dettaï; Guy Duhamel

    2013-01-01

    There has been a significant body of literature on species flock definition but not so much about practical means to appraise them. We here apply the five criteria of Eastman and McCune for detecting species flocks in four taxonomic components of the benthic fauna of the Antarctic shelf: teleost fishes, crinoids (feather stars), echinoids (sea urchins) and crustacean arthropods. Practical limitations led us to prioritize the three historical criteria (endemicity, monophyly, species richness) ...

  18. 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 274bp 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. PMID:26874670

  19. Acclimation and thermal tolerance in Antarctic marine ectotherms

    OpenAIRE

    Peck, L.S.; Morley, S.A.; Richard, J.; Clark, M.S.

    2014-01-01

    Antarctic marine species have evolved in one of the coldest and most temperature-stable marine environments on Earth. They have long been classified as being stenothermal, or having a poor capacity to resist warming. Here we show that their ability to acclimate their physiology to elevated temperatures is poor compared with species from temperate latitudes, and similar to those from the tropics. Those species that have been demonstrated to acclimate take a very long time to do so, with Antarc...

  20. Josephson π state induced by valley polarization

    Science.gov (United States)

    Wang, Jun; Yang, Y. H.; Chan, K. S.

    2014-02-01

    We theoretically explore possible π-state Josephson junctions made from graphene-like two-dimensional materials (G) with the honeycomb lattice structure. It is shown that the valley polarization in the G sheet could lead to a 0-π state transition of the Josephson junction because of the valley-singlet Cooper pairs acquiring a nonzero momentum. When the valley-mixing scattering exists in the interfaces of the junction due to lattice mismatch, an odd-frequency valley-triplet supercurrent flows in the system even though the G sheet is fully valley polarized, and the supercurrent is characterized by a rapid atomic-scale oscillation with a periodicity of three lattice constants.

  1. Effect of the drying cycle on dried tile mechanical strength

    Energy Technology Data Exchange (ETDEWEB)

    Amoros, J.L.; Sanchez, E.; Cantavella, V.; Monzo, M.; Jarque, J.C. [Universitat Jaume I, Castellon (Spain). Inst. de Tecnologia Ceramica; Timellini, G. [Centro Ceramico, Bologna (Italy); Leak, N. [British Ceramic Research Association, Stoke-on-Trent (United Kingdom)

    2002-07-01

    The study shows that the industrial ceramic tile drying rate enormously affects dried tile mechanical strength. Tiles dried in an industrial facility were used to determine the variation of dried tile mechanical strength with storage time in a moisture-free container. Dried tile mechanical strength rose with storage time under these conditions. Under the most favourable conditions, dry mechanical strength increased by up to 60% of the starting value. The reason for the rise in mechanical strength is attributed to the relaxation of stresses that develop during fast industrial drying. The effect of the drying cycle on mechanical strength is interpreted on the basis of tile dimensional changes with temperature and moisture content during drying. This assumption was confirmed by laboratory experiments in a dilatometer. (orig.)

  2. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Tips & Prevention News Ask an Ophthalmologist Patient Stories Español Eye Health / Eye Health A-Z Dry Eye ... Cause Nighttime Glare? Sep 12, 2014 Leer en Español: ¿Qué Es el Ojo Seco? Find an Ophthalmologist ...

  3. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Get ophthalmologist-reviewed tips and information about eye health and preserving your vision. Privacy Policy Related The link between seasonal allergens and dry eye Apr 27, 2015 Choosing Wisely When It Comes to Eye Care, Part 5 Mar 19, 2013 Eye Makeup Safety ...

  4. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Glasses & Contacts Tips & Prevention News Ask an Ophthalmologist Español Eye Health / Eye Health A-Z Dry Eye ... Help Itchy Eyes Aug 18, 2014 Leer en Español: ¿Qué Es el Ojo Seco? Find an Ophthalmologist ...

  5. Dry Skin (Xerosis)

    Science.gov (United States)

    ... resources Meet our partners Español Donate Diseases and treatments Acne and rosacea Bumps and growths Color problems Contagious skin diseases ... Dry skin public SPOT Skin Cancer™ Diseases and treatments Acne and rosacea Bumps and growths Color problems Contagious skin diseases ...

  6. What Is Dry Eye?

    Medline Plus

    Full Text Available ... large volume of tears, overwhelming the tear drainage system. These excess tears then overflow from your eye. Next   Causes of Dry ... Newsletter Get ophthalmologist-reviewed tips and information about eye health and preserving your vision. Privacy ...

  7. Dry eye syndrome

    Science.gov (United States)

    ... second-hand smoke exposure Cold or allergy medicines Dry eye can also be caused by: Heat or chemical burns Previous eye surgery A rare autoimmune disorder in which the glands that produce tears are destroyed ( Sjögren's syndrome )

  8. On the Atmospheric Correction of Antarctic Airborne Hyperspectral Data

    Directory of Open Access Journals (Sweden)

    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.

  9. Extreme phenotypic plasticity in metabolic physiology of Antarctic Demosponges

    Directory of Open Access Journals (Sweden)

    Simon Anthony Morley

    2016-01-01

    Full Text Available Seasonal measurements of the metabolic physiology of four Antarctic demosponges and their associated assemblages, maintained in a flow through aquarium facility, demonstrated one of the largest differences in seasonal strategies between species and their associated sponge communities. The sponge oxygen consumption measured here exhibited both the lowest and highest seasonal changes for any Antarctic species; metabolic rates varied from a 25% decrease to a 5.8 fold increase from winter to summer, a range which was greater than all 17 Antarctic marine species (encompassing 8 phyla previously investigated and amongst the highest recorded for any marine environment. The differences in nitrogen excretion, metabolic substrate utilisation and tissue composition between species were, overall, greater than seasonal changes. The largest seasonal difference in tissue composition was an increase in CHN (Carbon, Hydrogen and Nitrogen content in Homaxinella balfourensis, a pioneer species in ice-scour regions, which changed growth form to a twig-like morph in winter. The considerable flexibility in seasonal and metabolic physiology across the Demospongiae likely enables these species to respond to rapid environmental change such as ice-scour, reductions in sea ice cover and ice-shelf collapse in the Polar Regions, shifting the paradigm that polar sponges always live life in the slow lane. Great phenotypic plasticity in physiology has been linked to differences in symbiotic community composition, and this is likely to be a key factor in the global success of sponges in all marine environments and their dominant role in many climax communities.

  10. Phylogenetic position of Antarctic Scalpelliformes (Crustacea: Cirripedia: Thoracica)

    Science.gov (United States)

    Linse, Katrin; Jackson, Jennifer A.; Fitzcharles, Elaine; Sands, Chester J.; Buckeridge, John S.

    2013-03-01

    The phylogenetic relationships of seven Antarctic barnacle species, one verrucomorph and six scalpelliforms from the Scotia, Weddell and Ross seas were investigated using DNA sequences from two nuclear genes (18 S and 28 S) and one mitochondrial gene (COI), with a combined total length of 3,151 base pairs. Analyses of these new sequences, together with those of previously published ibliform, lepadiform, scalpelliform, balanomorph and verrucomorph species, confirm that the Scalpelliformes are not monophyletic. Bayesian and maximum likelihood analyses consistently recovered a monophyletic group which comprised Ornatoscalpellum stroemii (Sars) and the Southern Ocean scalpellomorphs; Arcoscalpellum sp. from the Weddell Sea, Arcoscalpellum africanum from Elephant Island, A. bouveti from Bouvet Island, the circum-Antarctic Litoscalpellum discoveryi, Litoscalpellum sp. from Shag Rocks and Scalpellum sp. from the Falkland Trough. We also used multiple fossil constraints in a relaxed clock Bayesian framework to estimate divergence times for the 18 S+28 S phylogeny. Our results indicate a mid Cretaceous divergence for the Weddell Sea Arcoscalpellum sp, followed by a late Cretaceous divergence from the North Atlantic O. stroemii. Subsequent to this, the Antarctic scalpellomorphs began to radiate at the Cretaceous-Tertiary boundary. Monophyly within the scalpellid genera Arcoscalpellum, Litoscalpellum and Scalpellum was strongly rejected by all loci. Our results show incongruence between taxonomy and molecular systematics and highlight the need for more species to be sequenced as well as taxonomic revisions to resolve uncertainties in the phylogenetic relationships of the stalked barnacles.

  11. Antarctic birds (Neornithes during the Cretaceous-Eocene times

    Directory of Open Access Journals (Sweden)

    C. Tambussi

    2007-12-01

    Full Text Available Antarctic fossil birds can be confidently assigned to modern orders and families, such as a goose-like anseriform, two loon-like and a seriema-like, all recorded before the K/T boundary at the López de Bertodano Fomation. Also, the discovery of a ratite and a phororhacids from the uppermost levels of the Submeseta Allomember (Late Eocene, suggests that West Antarctica was functional to dispersal routes obligate terrestrial birds. Representatives of Falconiformes Polyborinae, Ciconiiformes, Phoenicoteriformes, Charadriiformes, Pelagornitidae and Diomedeidae constitute the non-penguin avian assemblages of the Eocene of La Meseta Formation. Fifthteen Antarctic species of penguins have been described including the oldest penguin of West Antarctica, Croswallia unienwillia. The Anthropornis nordenskjoeldi Biozone (36.13 and 34.2 Ma, Late Eocene is characterized by bearing one of the highest frequencies of penguin bones and the phospatic brachiopod Lingula., together with remains of Gadiforms, sharks and primitive mysticete whales. Anthropornis nordenskjoeldi, Delphinornis gracilis, D. arctowski, Archaeospheniscus lopdelli, and Palaeeudyptes antarcticus are exclusively of the La Meseta Formation. Anthropornis nordenskjoeldi was evidently the largest penguin recorded at the James Ross Basin, whereas Delphinornis arctowski is the smallest, and include one of the worldwide highest morphological and taxonomic penguin diversity living sympatrically. The progressive climate cooling of the Eocene could have affected the penguin populations, because of climatic changes linked with habitat availability and food web processes. However, there is not available evidence about Antarctic penguins' evolution after the end of the Eocene.

  12. A transcriptome resource for the Antarctic pteropod Limacina helicina antarctica.

    Science.gov (United States)

    Johnson, Kevin M; Hofmann, Gretchen E

    2016-08-01

    The pteropod Limacina helicina antarctica is a dominant member of the zooplankton assemblage in the Antarctic marine ecosystem, and is part of a relatively simple food web in nearshore marine Antarctic waters. As a shelled pteropod, Limacina has been suggested as a candidate sentinel organism for the impacts of ocean acidification, due to the potential for shell dissolution in undersaturated waters. In this study, our goal was to develop a transcriptomic resource for Limacina that would support mechanistic studies to explore the physiological response of Limacina to abiotic stressors such as ocean acidification and ocean warming. To this end, RNA sequencing libraries were prepared from Limacina that had been exposed to a range of pH levels and an elevated temperature to maximize the diversity of expressed genes. RNA sequencing (RNA-seq) was conducted on an Illumina NextSeq500 which produced 339,000,000 150bp paired-end reads. The de novo transcriptome was produced using Trinity and annotation of the assembled transcriptome resulted in the identification of 81,229 transcripts in 137 KEGG pathways. This RNA-seq effort resulted in a transcriptome for the Antarctic pteropod, Limacina helicina antarctica, that is a major resource for an international marine science research community studying these pelagic molluscs in a global change context. PMID:27157132

  13. Metagenomic Analysis of Bacterial Communities of Antarctic Surface Snow

    Directory of Open Access Journals (Sweden)

    Anna Lopatina

    2016-03-01

    Full Text Available The diversity of bacteria present in surface snow around four Russian stations in Eastern Antarctica was studied by high throughput sequencing of amplified 16S rRNA gene fragments and shotgun metagenomic sequencing. Considerable class- and genus-level variation between the samples was revealed indicating a presence of inter-site diversity of bacteria in Antarctic snow. Flavobacterium was a major genus in one sampling site and was also detected in other sites. The diversity of flavobacterial type II-C CRISPR spacers in the samples was investigated by metagenome sequencing. Thousands of unique spacers were revealed with less than 35% overlap between the sampling sites, indicating an enormous natural variety of flavobacterial CRISPR spacers and, by extension, high level of adaptive activity of the corresponding CRISPR-Cas system. None of the spacers matched known spacers of flavobacterial isolates from the Northern hemisphere. Moreover, the percentage of spacers with matches with Antarctic metagenomic sequences obtained in this work was significantly higher than with sequences from much larger publically available environmental metagenomic database. The results indicate that despite the overall very high level of diversity, Antarctic Flavobacteria comprise a separate pool that experiences pressures from mobile genetic elements different from those present in other parts of the world. The results also establish analysis of metagenomic CRISPR spacer content as a powerful tool to study bacterial populations diversity.

  14. Estrutura do componente arbóreo e características edáficas de dois fragmentos de floresta estacional decidual no vale do rio Araguari, MG, Brasil Tree layer structure and soil characteristics of two deciduous dry forests in the Araguari river valley, Minas Gerais State, Brazil

    Directory of Open Access Journals (Sweden)

    Ariane de Souza Siqueira

    2009-03-01

    Full Text Available Este trabalho investigou a estrutura do componente arbóreo e as características edáficas de duas florestas deciduais (doravante Funil 1 e Funil 2 localizadas no vale do rio Araguari, Triângulo Mineiro. Foram demarcadas 60 parcelas de 10×20 m em cada área. Todas as árvores com circunfer��ncia a 1,30 m de altura >15 cm foram amostradas. Para o estudo do solo foram realizadas análises físicas e químicas de 20 amostras de cada ambiente. Para verificar possíveis relações entre as características do solo e a distribuição das espécies foram realizadas análises de correspondência canônica (CCA. Funil 1 apresentou densidade de 1695 ind./ha e área basal total de 16,25 m²/ha. Foram amostradas 64 espécies, 49 gêneros e 32 famílias nesse ambiente. Funil 2 apresentou densidade de 937,5 ind./ha, área basal total de 14,02 m²/ha e total de 46 espécies, 39 gêneros e 22 famílias. O índice de diversidade de Shannon foi de 2,76 (Funil 1 e 2,59 (Funil 2, sendo a equabilidade semelhante para os dois ambientes (J' = 0,66. As análises químicas evidenciaram fortes semelhanças entre os solos estudados. Em contraste, houve diferença considerável dos parâmetros físicos desses solos. A umidade dos solos de Funil 1 e 2 variou ao longo do ano (ANOVA F = 367,67; gl = 3; p This study aimed to analyze the vegetation structure and soil characteristics of two deciduous forests, hereafter referred to as Funil 1 and Funil 2, located in the Araguari river valley, Triângulo Mineiro region. Sixty 10×20 m plots were laid out in each forest. All trees with a minimum circumference of 15 cm at 1.30 m above ground were sampled. Soil samples were collected from 20 plots in each forest. Canonical correspondence analysis (CCA was used to check relationships between species distribution and soil characteristics. Funil 1 had a density of 1695 ind./ha and basal area of 16.25 m²/ha. A total of 64 species, 49 genera and 32 families were found in the area

  15. Geomorphological record of transformations of upland river valley bottoms at variable rate of gully erosion (case study: Wieprz River valley in Roztocze)

    Science.gov (United States)

    Kociuba, Waldemar

    2014-06-01

    In the upland geosystems of the moderate climate zone, any change in the conditions of functioning of a catchment causes a response of the system involving variable dynamics of fluvial processes (Gregory, Walling 1973; Schumm 1977, 1981; Kostrzewski, Szpikowski 2003; Świeca, Kociuba 2007). In the conditions of low anthropopressure, the direction and intensity of the processes modelling the valley bottom are determined by environmental factors, i.e. the geology and lithology of sediments, and land relief, and climate-driven factors, i.e. precipitation and groundwater supply determining water and sediment discharge rate (Froehlich 1982; Kostrzewski et al. 1994; Krzemień 1999; Dearing, Jones 2003, Meybeck et al. 2003; Kociuba et al. 2003; Świeca, Kociuba 2007; Rodzik et al. 2008). In the conditions of strong anthropopressure, the processes of transformation of the valley bottom can be largely accelerated due to disturbances in the stability of the catchment’s environmental conditions. Their geomorphological ef fects are manifested in changes in the channel shape (in the plan and cross profile), and in the modelling of the zone outside the channel, as a result of both flood and delluvial sediment deposition, particularly in the mouth zones of dry valleys and erosional dissections (Bork 1989; Rodzik et al. 2008; Brown 2009). Transformations of valley landforms resulting from changes in natural conditions and anthropopressure on the valley system can be traced based on the example of the meridional part of the Roztocze section of the Wieprz River valley (Fig. 1) - a typical medium-sized upland river of the moderate climate zone (Rodzik et al. 2008). The modern relief of the alluvial plain of the Roztocze fragment of the Wieprz River valley results from complex morphogenetic processes (Kociuba, Brzezińska-Wójcik 2002; Kociuba, Superson 2004). The primary morphostructural features developed with the contribution of tectonic movements in the Neogene and Early

  16. Dissolved black carbon in Antarctic lakes: Chemical signatures of past and present sources

    Science.gov (United States)

    Khan, Alia L.; Jaffé, Rudolf; Ding, Yan; McKnight, Diane M.

    2016-06-01

    The perennially ice-covered, closed-basin lakes in the McMurdo Dry Valleys, Antarctica, serve as sentinels for understanding the fate of dissolved black carbon from glacial sources in aquatic ecosystems. Here we show that dissolved black carbon can persist in freshwater and saline surface waters for thousands of years, while preserving the chemical signature of the original source materials. The ancient brines of the lake bottom waters have retained dissolved black carbon with a woody chemical signature, representing long-range transport of black carbon from wildfires. In contrast, the surface waters are enriched in contemporary black carbon from fossil fuel combustion. Comparison of samples collected 25 years apart from the same lake suggests that the enrichment in anthropogenic black carbon is recent. Differences in the chemical composition of dissolved black carbon among the lakes are likely due to biogeochemical processing such as photochemical degradation and sorption on metal oxides.

  17. Isolation of selenium organic species from antarctic krill after enzymatic hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Siwek, Mariana; Galunsky, Boris [Technical University Hamburg-Harburg, Institute of Biotechnology II, Hamburg (Germany); Niemeyer, Bernd [GKSS Research Centre, Institute for Coastal Research, Geesthacht (Germany); University of the Federal Armed Forces Hamburg, Institute of Thermodynamics, Hamburg (Germany)

    2005-02-01

    Total selenium content and its distribution in the soluble and insoluble protein-bound fractions obtained after aqueous extraction of antarctic krill samples were determined. About 26% of the total selenium (2.4 {mu}g g{sup -1} dry weight) was found in the supernatant; the rest was in the pellet. Isolation of low molecular selenium-containing fractions was also performed by enzymatic digestion of the protein, followed by size-exclusion chromatography in conjunction with atomic absorption spectrometry. From the applied various proteinases (pronase E, subtilisin Carlsberg, trypsin, chymotrypsin, proteinase and proteinase N from Bacillus subtilis and Novo 0.6 MPX enzyme), the treatment with pronase E led to best recovery of selenium. About 96% of the total Se was found in the hydrolysate, mainly in low molecular weight fractions. Eighty percent of the Se species were in fractions with molecular weights in the range of amino acids and short peptides. High-performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC-ICP-MS) allowed the identification of selenomethionine and the assumption that selenocystine or its derivatives were the main species in these fractions. (orig.)

  18. Climate Variability and Water-Regulation Effects on Surface Water and Groundwater Interactions in California's Central Valley

    Science.gov (United States)

    Munoz-Arriola, F.; Dettinger, M. D.; Hanson, R. T.; Faunt, C.; Cayan, D. R.

    2011-12-01

    California's Central Valley is one of the most important agricultural areas in the world and is highly dependent on the availability and management of surface water and groundwater. As such, it is a valuable large-scale system for investigating the interaction of climate variability and water-resource management on surface-water and groundwater interactions. In the Central Valley, multiple tools are available to allow scientists to understand these interactions. However, the full effect of human activities on the interactions occurring along the Aquifer-Soil-Plant-Atmosphere continuum remains uncertain. Two models were linked to investigate how non-regulated (natural conditions) and regulated (releases from dams) surface-water inflows from the surrounding contributing drainage areas to the alluvial plains of the Central Valley affects the valley's surface-water supply and groundwater pumpage under different climate conditions. The Variable Infiltration Capacity (VIC) macroscale (surface) hydrologic model was used to estimate the non-regulated streamflow. The U.S. Geological Survey's recently developed Central Valley Hydrologic Model (CVHM) was used to route both the regulated and non-regulated streamflow to the Central Valley and simulate the resulting hydrologic system. The CVHM was developed using MODFLOW's Farm Process (MF-FMP) in order to simulate agricultural water demand, surface-water deliveries, groundwater pumpage, and return flows in 21 water-balance subregions. As such, the CVHM simulates conjunctive use of water, providing a broad perspective on changes in the water systems of the Valley. Inflows from the contributing mountain watersheds are simulated in CVHM using the streamflow-routing package for the 1961-2003 time period. In order to analyze the affect of climate variability, dry and wet years were identified from below the 10th and above the 90th percentiles, respectively, in a multi-decadal time series (1961-2003) of surface-water inflows. The

  19. Spray Drying Processing: granules production and drying kinetics of droplets

    International Nuclear Information System (INIS)

    Spray drying is a unit operation very common in many industrial processes. For each particular application, the resulting granulated material must possess determined properties that depend on the conditions in which the spray drying processing has been carried out, and whose dependence must be known in order to optimize the quality of the material obtained. The large number of variables that influence on the processes of matter and energy transfer and on the formation of granular material has required a detailed analysis of the drying process. Over the years there have been many studies on the spray drying processing of all kind of materials and the influence of process variables on the drying kinetics of the granulated material properties obtained. This article lists the most important works published for both the spray drying processing and the drying of individual droplets, as well as studies aimed at modeling the drying kinetics of drops. (Author)

  20. Study on drying rate in contact drying with flexible screen

    Institute of Scientific and Technical Information of China (English)

    王伟宏; 陆仁书; 张显权

    2000-01-01

    The moisture contents (MC) of popular veneers were tested in Composition Board Laboratory of Northeast Forestry University by contact drying with flexible screen. The influence factors considered included temperature, initial moisture contents (IMC), and veneer thickness. Veneer-drying laws under different hot press conditions were analyzed. The results showed that the drying rate increased with temperature rising. 160℃ was considered to be more efficient than 140℃ and 180℃ because excessive high temperature has no significant contribution to drying rate. IMC had significant effect on drying rate. The veneer with high IMC had a higher drying rate at above fiber saturation point (FSP) and a lower drying rate at below FSP, compared to the veneer with low IMC. Average drying rate also varied with thickness in power law.

  1. Microwave drying of radwaste

    International Nuclear Information System (INIS)

    This paper briefly discusses how the microwave investigation began, what the investigators did and what the initial results indicate. Initial scoping tests using a 450 watt Sanyo microwave oven followed by experiments conducted with a 2 1/2 kilowatt microwave unit showed that resins could be dried without decomposing when temperature was kept below 2500F, and that volume reduction of at least two was possible. These tests show that microwave drying is easy and cost effective. Future plans are to put together a 30 kilowatt microwave unit which will be large enough to handle 5000 cubic feet of resin a year operating at about 60% capacity factor. Temperature measurements will be made with a probe. The unit will consist of condensers, water cooled stirrers, microwave power supply and engineering tanks which will cost anywhere from $$350,000 to $500,000

  2. An unusually dry story

    Directory of Open Access Journals (Sweden)

    Srinivas Rajagopala

    2015-01-01

    Full Text Available We present a middle-aged woman with a prior history of central nervous system (CNS demyelinating disorder who presented with an acute onset quadriparesis and respiratory failure. The evaluation revealed distal renal tubular acidosis with hypokalemia and medullary nephrocalcinosis. Weakness persisted despite potassium correction, and ongoing evaluation confirmed recurrent CNS and long-segment spinal cord demyelination with anti-aquaporin-4 antibodies. There was no history of dry eyes or dry mouth. Anti-Sjogren′s syndrome A antigen antibodies were elevated, and there was reduced salivary flow on scintigraphy. Coexistent antiphospholipid antibody syndrome with inferior vena cava thrombosis was also found on evaluation. The index patient highlights several rare manifestations of primary Sjogren′s syndrome (pSS as the presenting features and highlights the differential diagnosis of the clinical syndromes in which pSS should be considered in the Intensive Care Unit.

  3. Dry alcohol production plant

    Directory of Open Access Journals (Sweden)

    Stanković Mirjana S.

    2003-01-01

    Full Text Available The IGPC Engineering Department designed basic projects for dry alcohol production plant, using technology developed in the IGPC laboratories. Several projects were completed: technological, machine, electrical, automation. On the basis of these projects a production plant with a capacity of 40 m3/y was manufactured, at "Zorka Pharma", Šabac in 1995-1996. The product meets all quality demands, as well as environmental regulations. The dry alcohol production process is fully automatized. There is no waste in the process, neither gaseous, nor liquid. The chosen process provides safe operation according to temperature regime and resistance in the pipes, air purification columns and filters. Working at increased pressure is suitable for evaporation and condensation at increased temperatures. The production process can be controlled manually, which is necessary during start-up, and repairs.

  4. Results of environmental monitoring in the Kinta Valley and Cameron Highland areas

    International Nuclear Information System (INIS)

    The environmental radioactivity of the Kinta Valley and the Cameron Highlands show relative high values of gamma and alpha radiation. Both types of radiation are strongly related to meteorological conditions. In the Kinta Valley the average environmental values for Ra-222 are I 00 Bq/m sup 3 air. The monitoring chart shows a sinus shaped curve of the Radon 222 daughter concentration (EER = energy equivalent radon concentration). The concentration levels differ by I 0 times from a low in the late afternoon (around 18:00) and a high with the sunrise in the early morning (around 7:00). In the Kinta Valley and at the Pangkor island the observed interval is 24-hours. In the Kinta Valley three different surveys each of one week length showed, that the daily fluctuations exists over the whole year and doe not depend on rainy or dry seasons.. In the Cameron Highlands the outdoor radioactivity varies much faster than in the valley. There wash-out and building up periods during and between rain falls control external gamma and alpha concentration. Immediately after wash-out local gamma values can rise to 10 μSv/hour near the ground. It is concluded that the radioactivity concentration in the air is controlled by the building up time of the Rn 222 (around two hours) and the Rn 220 progeny (around 12 hours). An equilibrium factor of around 0.2 to 0.3 shows that full equilibrium is never reached in the air system. The calculation of the yearly external exposure is only possible with the knowledge of the local monitored concentration curve. A first calculation of the external dose rate for the persons living in the Kinta Valley was made. The calculations suggest dose rates between 5 and 15 mSv per year. High effective doses rates are expected film inhalation of indoor Radon progeny concentrations and from ingestion of contaminated food. (author)

  5. PECULIARITIES OF DRY FRICTION

    OpenAIRE

    Каgаn Mikhail Lazarevich; Antonov Viktor Ivanovich; Belov Viktor Anatolevich

    2012-01-01

    Some peculiarities of dry friction that represent the outcomes of several well-known physical phenomena but that are insufficiently accurately and simply explained in the scientific literature, are analyzed in this paper. The authors research into the reasons for the oscillation of strings of bowed string instruments in furtherance of the laws of mechanics; they also explain differences in the sound produced by strings of bowed and plucked instruments; they study the reasons for t...

  6. Dry Eye Syndrome

    Directory of Open Access Journals (Sweden)

    Mohammad-Ali Javadi

    2011-01-01

    Full Text Available Our understanding of keratoconjunctivitis sicca (KCS, also known as dry eye syndrome, has been changed over recent years. Until lately, the condition was thought to be merely due to aqueous tear insufficiency. Today, it is understood that KCS is a multifactorial disorder due to inflammation of the ocular surface and lacrimal gland, neurotrophic deficiency and meibomian gland dysfunction. This change in paradigm has led to the development of new and more effective medications.

  7. The hydrological regime of a forested tropical Andean valley

    Directory of Open Access Journals (Sweden)

    K. E. Clark

    2014-07-01

    Full Text Available The hydrology of tropical mountain catchments plays a central role in ecological function, geochemical and biogeochemical cycles, erosion and sediment production, and water supply in globally important environments. There have been few studies quantifying the seasonal and annual water budgets in the montane tropics, particularly in cloud forests. We investigated the water balance and hydrologic regime of the Kosñipata Valley (basin area 164.4 km2 over the period 2010–2011. The valley spans over 2500 m in elevation in the eastern Peruvian Andes and is dominated by tropical montane cloud forest with some high elevation puna grasslands. Catchment wide rainfall was 3028 ± 414 mm yr−1, calculated by calibrating Tropical Rainfall Measuring Mission (TRMM 3B43 rainfall with rainfall data from 9 meteorological stations in the valley. Cloud water input to streamflow was 316 ± 116 mm yr−1 (~10% of total inputs, calculated from an isotopic mixing model using deuterium excess (Dxs and δD of waters. Field stream flow was measured in 2010 by recording height and calibrating to discharge. River runoff was estimated to be 2796 ± 126 mm yr−1. Actual evapotranspiration (AET was 909 ± 182 mm yr−1, determined using the Priestley and Taylor – Jet Propulsion Laboratory (PT-JPL model. The overall water budget was balanced within 10%. Relationships between monthly rainfall and river runoff follow an anti-clockwise hysteresis through the year, with a persistence of high runoff after the end of the wet season. The size of the soil- and shallow ground-water reservoir is most likely insufficient to explain sustained dry season flow. Thus, the observed hysteresis in rainfall-runoff relationships is best explained by sustained groundwater flow in the dry season, which is consistent with the water isotope results that suggest persistent wet season sources to stream flow throughout the year. These results demonstrate the importance of transient groundwater

  8. Mitochondrial Acclimation Capacities to Ocean Warming and Acidification Are Limited in the Antarctic Nototheniid Fish, Notothenia rossii and Lepidonotothen squamifrons

    OpenAIRE

    Strobel, Anneli; Graeve, Martin; Poertner, Hans O.; Mark, Felix C

    2013-01-01

    Antarctic notothenioid fish are characterized by their evolutionary adaptation to the cold, thermostable Southern Ocean, which is associated with unique physiological adaptations to withstand the cold and reduce energetic requirements but also entails limited compensation capacities to environmental change. This study compares the capacities of mitochondrial acclimation to ocean warming and acidification between the Antarctic nototheniid Notothenia rossii and the sub-Antarctic Lepidonotothen ...

  9. 78 FR 66074 - Notice of Permit Applications Received Under the Antarctic Conservation Act of 1978 (Pub. L. 95-541)

    Science.gov (United States)

    2013-11-04

    ... the Antarctic Conservation Act of 1978 (Pub. L. 95-541), as amended by the Antarctic Science, Tourism..., Technology, Engineering, and Mathematics) STEM educational purposes. The gathered materials would be used to create lesson plans about Antarctic Exploration that focus on science, technology, engineering...

  10. Irrigation channels of the Upper Rhone valley (Switzerland). Geomorphological analysis of a cultural heritage

    Science.gov (United States)

    Reynard, Emmanuel

    2016-04-01

    The Upper Rhone valley (Canton of Valais, Switzerland) is characterised by dry climatic conditions that explain the presence of an important network (about 800 km) of irrigation channels - called Bisses in the French-speaking part of the canton or Suonen in the German-speaking area - dating back to the Middle Ages. This network constitutes a cultural heritage and during the last 30 years these agricultural infrastructures have sparked a renewed interest for tourist and cultural reasons. Indeed, the paths along the channels are used as tourist trails and several abandoned channels have been renovated for tourist use. Based on an inventory of the Bisses/Suonen of Valais, the proposed communication has three aims: (1) to analyse the geomorphological context (morphometric analysis, structural geomorphology, main processes) of various types of channels and to show the impact of the geomorphological context on the building techniques; (2) to identify particularly active processes along the channels; (3) to classify the Bisses/Suonen according to their geomorphological value and to their geomorphological sensitivity, and to propose managing measures. Structural and climatic conditions influence the geomorphological context of the channels. In a structural point of view, irrigation channels are developed in three main contexts: (1) in the Aar Massif crystalline basement; (2) in the limestone and marl cover nappes of the Helvetic Alps; (3) in the metamorphic cover nappes of the Penninic domain. The Rhone River valley is boarded by two high mountain ranges: the Penninic Alps in the South and the Bernese Alps in the North. Because of rain shadow effects, the climate is relatively dry and, between Brig and Martigny, annual rainfall is not more than 600 mm at 500 m ASL and 800 mm at 1600 m ASL. Nevertheless, due to important vertical precipitation gradients annual rainfall totals are high at high altitudes. On the southern facing tributary valleys, the dry climatic conditions

  11. Nitramine Drying & Fine Grinding Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Nitramine Drying and Fine Grinding Facility provides TACOM-ARDEC with a state-of-the-art facility capable of drying and grinding high explosives (e.g., RDX and...

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

    Science.gov (United States)

    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

  13. Soil Water Contents of Different Vegetation Types in the Ecotone between Dry-hot Valleys and Mountain Forest in the Upper Reaches of the Minjiang River%岷江上游山地森林/干旱河谷交错带几种植被类型土壤含水量研究

    Institute of Scientific and Technical Information of China (English)

    胡天钧; 周义贵; 冯毅; 宋鹏

    2011-01-01

    The soil water content is an important mark of the soil quality. It affects not only the physicochemical properties hut also distribution and absorption of mineral nutrients of plant, and at the same time it has the influence on the change of soil heat flux. The drying method and cutting-ring method were used to determine the physical properties of soil, and emphasis was to know the change of 0 - 40cm soil water content under different vegetation types in this area. Through determining soil water content in April, July, September and November, the results showed that the soil water content reached maximum value in September under the same vegetation types except the shrub land, and displayed positive correlation with the rainy season of this area, under the shrub land it continued to increase from April to November in 2007. In the same month,the status of soil water content under different vegetation types was: secondary forest 〉 Populus mixed with Salix 〉 shrub land 〉 needle-broad leaved mixed forest 〉 black locust forest 〉 steep waste land 〉 fiat waste land 〉 Cupressus chengiana forest, but in September and November, the soil water content under the shrub land was more than that under the other vegetation types.%采用烘干法和环刀法对土壤物理性质进行了测定,目的是为了重点了解岷江上游山地森林/干旱河谷交错带的不同植被类型下0~40cm土壤含水量的变化。经过2007年4月、7月、9月、11月四个不同时期的测定,结果表明:同一植被类型下(除灌木林地)土壤含水量9月份的最大,与当地的雨季呈现同增同减的关系,而灌木林地下的呈现从4月到11月的持续增加的变化。在同一月份中,不同植被下的土壤含水状况为:次生林地〉杨柳混交林地〉灌木林地〉针阔混交林地〉刺槐林地〉陡荒地〉平荒地〉岷江柏林地的变化关系,但是在9月和11月中,灌木林地下的

  14. Law 16.518 Antarctic Treaty: approve the protocols about Environment protection and annex s

    International Nuclear Information System (INIS)

    The treaty Antarctic in their appendix C in its articles is about the elimination of residuals by means of its removal of the area of having Treated Antarctic among them radioactive materials, planning of the wastes, communication treatment and exam of the plans of treatment of wastes, treatment proceeding prevention of sea contamination ,discharge of hydrocarbons petroliferous, discharge of liquid noxious substances

  15. Living resources of Antarctic India's contribution to exploration and future plans for exploration

    Digital Repository Service at National Institute of Oceanography (India)

    Parulekar, A.H.

    stream_size 7 stream_content_type text/plain stream_name Proc_Workshop_Antarct_Stud_1990_459.pdf.txt stream_source_info Proc_Workshop_Antarct_Stud_1990_459.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset...

  16. 78 FR 51213 - Notice of Permits Issued Under the Antarctic Conservation Act of 1978

    Science.gov (United States)

    2013-08-20

    ... Antarctic Science, Tourism and Conservation Act of 1996, (16 U.S.C 2401 et seq.), and Article 7 of the... Antarctic Science, Tourism and Conservation Act of 1996, (16 U.S.C 2401 et seq). SUMMARY: On March 31,...

  17. Escherichia coli out in the cold: Dissemination of human-derived bacteria into the Antarctic microbiome.

    Science.gov (United States)

    Power, Michelle L; Samuel, Angelingifta; Smith, James J; Stark, Jonathon S; Gillings, Michael R; Gordon, David M

    2016-08-01

    Discharge of untreated sewage into Antarctic environments presents a risk of introducing non-native microorganisms, but until now, adverse consequences have not been conclusively identified. Here we show that sewage disposal introduces human derived Escherichia coli carrying mobile genetic elements and virulence traits with the potential to affect the diversity and evolution of native Antarctic microbial communities. We compared E. coli recovered from environmental and animal sources in Antarctica to a reference collection of E. coli from humans and non-Antarctic animals. The distribution of phylogenetic groups and frequency of 11 virulence factors amongst the Antarctic isolates were characteristic of E. coli strains more commonly associated with humans. The rapidly emerging E. coli ST131 and ST95 clones were found amongst the Antarctic isolates, and ST95 was the predominant E. coli recovered from Weddell seals. Class 1 integrons were found in 15% of the Antarctic E. coli with 4 of 5 identified gene cassette arrays containing antibiotic resistance genes matching those common in clinical contexts. Disposing untreated sewage into the Antarctic environment does disseminate non-native microorganisms, but the extent of this impact and implications for Antarctic ecosystem health are, as yet, poorly understood. PMID:27179324

  18. Standing crop and growth rates of net phytoplankton and nanoplankton in Antarctic waters

    Digital Repository Service at National Institute of Oceanography (India)

    Goes, J.I.; Fondekar, S.P.; Parulekar, A.H.

    stream_size 16 stream_content_type text/plain stream_name Proc_Workshop_Antarct_Stud_1990_419.pdf.txt stream_source_info Proc_Workshop_Antarct_Stud_1990_419.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset...

  19. UPREGULATION OF STRESS ASSOCIATED GENES IN THE OVERWINTERING STAGES OF THE ANTARCTIC MIDGE, BELGICA ANTARCTICA

    Science.gov (United States)

    We have investigated the molecular basis of stress resistance in the midge Belgica antarctica, the largest known free-living animal to adapt to a terrestrial existence on the Antarctic continent. Prevalent in specific locations throughout the Antarctic peninsula, this insect has a two-year life cyc...

  20. Ganges Valley Aerosol Experiment: Science and Operations Plan

    Energy Technology Data Exchange (ETDEWEB)

    Kotamarthi, VR

    2010-06-21

    emissions; and dust. The extended AMF deployment will enable measurements under different regimes of the climate and aerosol abundance—in the wet monsoon period with low aerosol loading; in the dry, hot summer with aerosols dispersed throughout the atmospheric column; and in the cool, dry winter with aerosols confined mostly to the boundary later and mid-troposphere. Each regime, in addition, has its own distinct radiative and atmospheric dynamic drivers. The aircraft operational phase will assist in characterizing the aerosols at times when they have been observed to be at the highest concentrations. A number of agencies in India will collaborate with the proposed field study and provide support in terms of planning, aircraft measurements, and surface sites. The high concentration of aerosols in the upper Ganges Valley, together with hypotheses involving several possible mechanisms with direct impacts on the hydrologic cycle of the region, gives us a unique opportunity to generate data sets that will be useful both in understanding the processes at work and in providing answers regarding the effects of aerosols on climate in a region where the perturbation is the highest.

  1. Changes in discharge and solute dynamics between a hillslope and a valley-bottom intermittent streams

    Directory of Open Access Journals (Sweden)

    S. Bernal

    2011-10-01

    Full Text Available We investigated differences on stream water flux as well as on chloride, carbon and nitrogen dynamics between two semiarid nested catchments, one at the hillslope and the other one at the valley-bottom. The two streams were intermittent, yet only the valley-bottom stream was embraced by a riparian forest and a well-developed alluvium with highly conductive coarse sediments. We found that stream water flux decreased by more than 40% from the hillslope to the valley-bottom during hydrological transition periods (from dry-to-wet and from wet-to-dry conditions, coinciding with periods when stream-to-aquifer fluxes prevailed. During the hydrological transition period, stream export of chloride, nitrate, and dissolved organic carbon decreased 34–97% between the hillslope and the valley-bottom catchments. There was a strong correlation between monthly differences in stream discharge and in stream Cl export between the two catchments. In contrast, monthly differences in stream export for bio-reactive solutes were only partially explained by stream discharge. In annual terms, stream nitrate export from the valley-bottom catchment (0.32 ± 0.12 kg N ha−1 yr−1 – average ± standard deviation was 30–50% lower than from the hillslope catchment (0.56 ± 0.32 kg N ha−1 yr−1. Although the riparian forest could be an extra source of organic matter to the valley-bottom stream, the annual export of dissolved organic carbon was similar between the two catchments (1.8 ± 1 kg C ha−1 yr−1. Our results suggested that stream hydrology was a strong driver of stream solute export during the hydrological transition period, and that hydrological retention in the alluvial zone could contribute to reduce stream water and solute export under semiarid conditions in the valley-bottom stream.

  2. 76 FR 22746 - Conecuh Valley Railway, LLC-Acquisition and Operation Exemption-Conecuh Valley Railroad Co., Inc.

    Science.gov (United States)

    2011-04-22

    ... Surface Transportation Board Conecuh Valley Railway, LLC--Acquisition and Operation Exemption--Conecuh Valley Railroad Co., Inc. Conecuh Valley Railway, LLC (CVR), a noncarrier, has filed a verified notice of exemption under 49 CFR 1150.31 to acquire from Conecuh Valley Railroad Co., Inc. (COEH), and to...

  3. Dry Processing Instant Photographic Systems

    Directory of Open Access Journals (Sweden)

    R. Hradaynath

    1985-01-01

    Full Text Available The technology, photographic characteristics, applications, advantages, limitations and possible lines of advancement of dry processing instant photographic systems viz. dry silver halide systems, diffusion transfer reversal materials, photothermographic systems, dry film peel-apart photoresists, photopolymers for holographic recording. thermoplastic recording systems and electrophotographic  systems have been discussed.

  4. Factors influencing the variations of PM10 aerosol dust in Klang Valley, Malaysia during the summer

    Science.gov (United States)

    Juneng, Liew; Latif, Mohd Talib; Tangang, Fredolin

    2011-08-01

    The associations between the variations of PM10 concentration during summer monsoon dry seasons over the Klang Valley, Malaysia and the local meteorological factors, synoptic weather conditions as well as the regional hotspots number were examined based on simple multiple linear regression analysis. The regressive relationships established, suggest that the variation of PM10 in Klang Valley was governed significantly by all of the examined factors. Local meteorological conditions are among those factors which governed the largest day-to-day variations of PM10 concentration in the Klang Valley areas during the dry season. When augmented by synoptic meteorological variables and foreign emission sources, a remarkable increase in the explained variance was apparent. On the other hand, domestic burning sources only had a minimal impact on PM10 fluctuations. Important synoptic weather patterns which influence the air pollution variations were also identified. These synoptic conditions include the strengthening of the summer monsoon southwesterly winds over the equatorial area. In addition, the formation of cyclonic circulation, associated with typhoon formation over the north-west Pacific and the South China Sea as well as over the Bay of Bengal, are found to have had a profound impact on PM10 variations over the Malaysian region through the modulation of regional moisture distributions.

  5. Synchronicity between ice retreat and phytoplankton bloom in circum-Antarctic polynyas

    Science.gov (United States)

    Li, Yun; Ji, Rubao; Jenouvrier, Stephanie; Jin, Meibing; Stroeve, Julienne

    2016-03-01

    Phytoplankton in Antarctic coastal polynyas has a temporally short yet spatially variant growth window constrained by ice cover and day length. Using 18-year satellite measurements (1997-2015) of sea ice and chlorophyll concentrations, we assessed the synchronicity between the spring phytoplankton bloom and light availability, taking into account the ice cover and the incident solar irradiance, for 50 circum-Antarctic coastal polynyas. The synchronicity was strong (i.e., earlier ice-adjusted light onset leads to earlier bloom and vice versa) in most of the western Antarctic polynyas but weak in a majority of the eastern Antarctic polynyas. The west-east asymmetry is related to sea ice production rate: the formation of many eastern Antarctic polynyas is associated with strong katabatic wind and high sea ice production rate, leading to stronger water column mixing that could damp phytoplankton blooms and weaken the synchronicity.

  6. Climate Change Impacts in the sub-Antarctic Islands Technical Report N.2 of ONERC

    International Nuclear Information System (INIS)

    Difficult to apprehend as a whole, the polar regions constitute the Arctic to the North, an ocean surrounded by emerged lands, and the Antarctic to the South, a continent bordered by the Austral Ocean where a belt of sub Antarctic islands lies. Climate change impacts on sub Antarctic islands are varied, direct and indirect: glacier retreat, more favourable conditions for introduced species, marine biodiversity modification, etc. This report discusses the French, British, Australian, South African and New Zealand sub Antarctic islands, the climatic evolutions and the resulting impacts, focused especially on biodiversity. The Observatoire National sur les Effets du Rechauffement Climatique and the International Polar Foundation have been joined in this endeavour by the French polar institute Paul-Emile Victor, the administration of the French Southern and Antarctic Lands (TAAF in French) and the International Union for the Conservation of Nature. (authors)

  7. Non isothermal drying process optimisation - Drying of clay tiles

    Science.gov (United States)

    Vasić, M.; Radojević, Z.

    2015-11-01

    In our previous studies we have developed a model for determination of the variable effective diffusivity and identification of the exact transition points between possible drying mechanisms. The next goal was to develop a drying regime which could in advance characterize the real non isothermal process of drying clay tiles. In order to do this four isothermal experiments were recorded. Temperature and humidity were maintained at 350C / 75%; 450C / 70%; 450C / 60% and 500C / 60%; respectively in each experiment. All experimentally collected data were analyzed and the exact transition points between possible drying mechanisms were detected. Characteristic drying period (time) for each isothermal drying mechanism was also detected. The real, non-isothermal drying process was approximated by 5 segments. In each of these segments approximately isothermal drying condition were maintained. Temperature and humidity of the drying air, in the first four segments, was maintained on the same level as in recorded isothermal experiments while in the fifth segment, it were maintained at 700C / 40%. The duration of the first four segments were calculated from the diagrams Deff - t respectively for each experiment. The clay tile in experiment five was dried without cracking using the proposed non isothermal drying regime.

  8. Meie ingel Silicon Valleys / Raigo Neudorf

    Index Scriptorium Estoniae

    Neudorf, Raigo

    2008-01-01

    Ettevõtluse Arendamise Sihtasutuse esinduse töölepanekust USAs Silicon Valleys räägib esinduse juht Andrus Viirg. Vt. ka: Eestlasi leidub San Franciscos omajagu; Muljetavaldav karjäär; USAga ammune tuttav

  9. Meie mees Silicon Valleys / Kertu Ruus

    Index Scriptorium Estoniae

    Ruus, Kertu, 1977-

    2007-01-01

    Ilmunud ka: Delovõje Vedomosti 5. dets. lk. 4. Peaminister Andrus Ansip avas Eesti Ettevõtluse Sihtasutuse esinduse Silicon Valley pealinnas San Joses. Vt. samas: Ränioru kliima on tehnoloogiasõbralik; Andrus Viirg

  10. Alluvial Boundary of California's Central Valley

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This digital dataset defines the extent of the alluvial deposits in the Central Valley of California and encompasses the contiguous Sacramento, San Joaquin, and...

  11. Safety Plan: Minnesota Valley National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This station safety plan should be viewed as a working tool for all employees of Minnesota Valley NWR. It contains information and instructions for emergencies,...

  12. Burrowing Owl - Palo Verde Valley [ds197

    Data.gov (United States)

    California Department of Resources — These burrowing owl observations were collected during the spring and early summer of 1976 in the Palo Verde Valley, eastern Riverside County, California. This is...

  13. Vegetation - San Felipe Valley [ds172

    Data.gov (United States)

    California Department of Resources — This Vegetation Map of the San Felipe Valley Wildlife Area in San Diego County, California is based on vegetation samples collected in the field in 2002 and 2005...

  14. Characterization of bacterial communities in lithobionts and soil niches from Victoria Valley, Antarctica.

    Science.gov (United States)

    Van Goethem, Marc W; Makhalanyane, Thulani P; Valverde, Angel; Cary, Stephen C; Cowan, Don A

    2016-04-01

    Here we provide the first exploration of microbial diversity from three distinct Victoria Valley edaphic habitats, namely lithobionts (hypoliths, endoliths) and surface soils. Using a combination of terminal restriction fragment length polymorphism (T-RFLP) analysis and 16S rRNA gene amplicon pyrosequencing we assess community structure and diversity patterns, respectively. Our analysis revealed that habitat type (endolithic versus hypolithic versus surface soils) significantly influenced bacterial community composition, even though dominant phyla such as Actinobacteria (41% of total reads) were common to all samples. Consistent with previous surveys in other Dry Valley ecosystems, we found that lithobionts were colonized by a few highly dominant phylotypes (such asGemmatimonasandLeptolyngbya). Our analyses also show that soil bacteria were more diverse and evenly distributed than initially expected based on previous evidence. In contrast to total bacteria, the distribution of Cyanobacteria was not strongly influenced by habitat type, although soil- and endolith-specific cyanobacterial lineages were found. The detection of cyanobacterial lineages in these habitats appears to be influenced by the dispersal of aquatic inocula from lacustrine communities or benthic mats which are abundant in Victoria Valley. Together, our results provide insights into the phylogenetic variation and community structure across niche habitats in Victoria Valley. PMID:26946500

  15. Valley-protected backscattering suppression in silicon photonic graphene

    CERN Document Server

    Chen, Xiao-Dong

    2016-01-01

    In this paper, we study valley degree of freedom in all dielectric silicon photonic graphene. Photonic band gap opening physics under inversion symmetry breaking is revisited by the viewpoint of nonzero valley Chern number. Bulk valley modes with opposite orbital angular momentum are unveiled by inspecting time-varying electric fields. Topological transition is well illustrated through photonic Dirac Hamiltonian. Valley dependent edge states and the associated valley-protected backscattering suppression around Z-shape bend waveguide have been demonstrated.

  16. Climate-dependent evolution of Antarctic ectotherms: An integrative analysis

    Science.gov (United States)

    Pörtner, Hans O.

    2006-04-01

    The paper explores the climate-dependent evolution of marine Antarctic fauna and tries to identify key mechanisms involved as well as the driving forces that have caused the physiological and life history characteristics observed today. In an integrative approach it uses the recent concept of oxygen and capacity limited thermal tolerance to identify potential links between molecular, cellular, whole-organism, and ecological characteristics of marine animal life in the Antarctic. As a generalized pattern, minimization of baseline energy costs, for the sake of maximized growth in the cold, appears as one over-arching principle shaping the evolution and functioning of Antarctic marine ectotherms. This conclusion is supported by recent comparisons with (sub-) Arctic ectotherms, where elevated levels of energy turnover result at unstable, including cold temperatures, and are related to wide windows of thermal tolerance and associated metabolic features. At biochemical levels, metabolic regulation at low temperatures in general, is supported by the cold compensation of enzyme kinetic parameters like substrate affinities and turnover numbers, through minute structural modifications of the enzyme molecule. These involve a shift in protein folding, sometimes supported by the replacement of individual amino acids. The hypothesis is developed that efficient metabolic regulation at low rates in Antarctic marine stenotherms occurs through high mitochondrial densities at low capacities and possibly enhanced levels of Arrhenius activation energies or activation enthalpies. This contrasts the more costly patterns of metabolic regulation at elevated rates in cold-adapted eurytherms. Energy savings in Antarctic ectotherms, largely exemplified in fish, typically involve low-cost, diffusive oxygen distribution due to high density of lipid membranes, loss of haemoglobin, myoglobin and the heat shock response, reduced anaerobic capacity, large myocytes with low ion exchange activities

  17. Antarctic marine bacteria versus UV-B irradiation

    International Nuclear Information System (INIS)

    The most important stages of knowledge development in Antarctic marine microbiology, from the beginning of this century, were reviewed and systematized. Multi-annual studies from 1978 to 1988 demonstrated a great variation in total and saprophytic bacterial numbers at different sites in the Antarctic. These sites included inshore waters (Admiralty Bay), open ocean waters (Drake Passage and Bransfield Strait), and the vicinity of pack-ice in Scotia Sea. Bacterial biomass, which is highly comparable to that of other organisms, combined with many times shorter bacterial generation time, (in case of saprophytic population it amounts to 17.5 h), must have profound consequences for cold marine ecosystems of the Antarctic. Higher numbers of bacteria were found in open surface waters, down to 75 m. High transparency of oceanic offshore waters causes that UV radiation (280-400 nm) penetrates to biologically effective depths to about 50 m. The UV-B sensitivity of 25 Antarctic bacterial strains from the following various habitats: coastal waters, krill stomach, krill feaces, water ice edge, water below ice and sea ice was examined. The strains were irradiated in UV-B transparent cuvettes on an optical bench with artificial UV-B (290 nm; 1.21 W. m-2 ] during 10 hours in temperature 4oC. ATP (adenosine triphosphate), number of bacterial cells, lethal effect of UV-B and survival of bacteria, total bacterial number, biovolume and changes in biochemical/physiological properties have been estimated. The results indicated a high interspecific variability in the sensitivity against UV-B. The ATP content show at the beginning of irradiation an increase (reaching typical for individual species maximum, at 0.5 to 4 hours) and afterwards a decrease to the level above zero (also characteristic of species). We hypothesize that first anabolic processes and after that catabolic processes are destroyed by UV. Survival of the bacterial strains ranged between 0 and 3.2%. Among 25 bacterial

  18. Sediment fluxes of an Antarctic palaeo-ice stream system

    Science.gov (United States)

    Hogan, Kelly; Larter, Robert; Smith, James; Hillenbrand, Claus-Dieter

    2016-04-01

    New marine-geophysical data (multibeam bathymetry, high-resolution acoustic profiles) acquired in 2014 have been integrated with heritage multichannel seismic-reflection and deep-tow boomer profiles from Anvers-Hugo Trough, western Antarctic Peninsula. From these datasets we have identified seismic facies relating to ice-stream advance and flow, ice-stream retreat, and post-glacial sedimentation processes. We identify multiple subglacial seismic units forming MSGL and other streamlined landforms at a variety of size scales. This may be indicative of multiple generations of ice-flow through the confluent ice-stream system. We also calculate the sediment volumes of a series of grounding-zone wedges (GZWs) located on the outer and mid-shelf that were produced during several stillstands in the trough as the grounded ice margin retreated through the system during deglaciation around c. 15-13 ka (from published core chronologies). Based on these volumes we consider the likely rates of subglacial sediment delivery by the Anvers Trough palaeo-ice stream and compare these to inferred flux rates from other palaeo- and modern Antarctic ice streams. In addition, we map the post-glacial glacimarine sediment package in the trough. Large mapped sediment thicknesses of this unit across the trough are consistent with high post-glacial sediment accumulation rates reported from cores acquired in the Anvers-Hugo Trough system. Previous authors have attributed this to exceptionally high primary productivity in a calving-bay re-entrant settings produced as ice retreated across the shelf on this part of the Antarctic margin.

  19. Performance of carrot genotypes at two Jequitinhonha Valley sites

    Directory of Open Access Journals (Sweden)

    Gustavo Antônio Mendes Pereira

    2015-12-01

    Full Text Available The successful commercial use of carrot depends on the choice of cultivars that are well-adapted to soil and climate conditions at the cultivation site and on good consumer acceptance. The objective of this study was to evaluate the performance of carrot cultivars grown in autumn-winter in two towns with different climatic characteristics, in the High Jequitinhonha Valley, MG, Brazil. The experiments were conducted on the Rio Manso farm, in the town of Couto de Magalhães de Minas and on Campus JK at UFVJM, in the town of Diamantina, Minas Gerais, Brazil. Six carrot cultivars (Brasília, Nantes, Kuronan, Esplanada, Planalto and Tornado were evaluated using a randomized complete block design with three replicates. The following morpho-agronomic characteristics were evaluated 100 days after sowing: shoot height, root length, root dry matter, total dry matter, harvest index, commercial yield and total yield root. The most suitable cultivars in Diamantina were Planalto, Tornado and Kuronan, and the cultivatar Planalto was the best suited to Couto de Magalhães de Minas. The agronomic performance of the cultivars was higher in Couto de Magalhães de Minas for the majority of the study variables, resulting in a higher total yield and commercial root yield. The climatic and soil conditions of Diamantina induced flowering in most cultivars, causing a loss to the commercial yield in autumn-winter cultivation.

  20. Prospects for surviving climate change in Antarctic aquatic species

    OpenAIRE

    Peck Lloyd S

    2005-01-01

    Abstract Maritime Antarctic freshwater habitats are amongst the fastest changing environments on Earth. Temperatures have risen around 1°C and ice cover has dramatically decreased in 15 years. Few animal species inhabit these sites, but the fairy shrimp Branchinecta gaini typifies those that do. This species survives up to 25°C daily temperature fluctuations in summer and passes winter as eggs at temperatures down to -25°C. Its annual temperature envelope is, therefore around 50°C. This is ty...

  1. Temperature-dependent enthalpy of oxygenation in Antarctic fish hemoglobins

    DEFF Research Database (Denmark)

    Fago, A.; Wells, R.M.G.; Weber, Roy E.

    1997-01-01

    (logP(50) vs 1/T) of D. mawsoni hemoglobin indicates that the enthalpy of oxygenation (slope of the plot) is temperature dependent and that at high temperatures oxygen-binding becomes less exothermic. Nearly linear relationships were found in the hemoglobins of the other two species. The data were...... literature data for the enthalpy of oxygenation in Antarctic fish hemoglobins derives from the use of the nonintegrated (linearized) form of the van't Hoff equation over different temperature ranges. The general assumption that a low heat of oxygenation in hemoglobins from polar animals represents an...

  2. 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

  3. Cryptococcus friedmannii, a new species of yeast from the Antarctic

    Science.gov (United States)

    Vishniac, H. S.

    1985-01-01

    Cryptococcus friedmannii Vishniac sp. nov. from an Antarctic cryptoendolithic community is a psychrophilic basidioblastomycete characterized by cream-colored colonies of cells with smooth, layered walls, budding monopolarly, producing amylose and extracellular proteinase, utilizing nitrate and D-alanine (inter alia) as nitrogen sources and L-arabinose, arbutin, cellobiose, D-glucuronate, maltose, melezitose, salicin, soluble starch, trehalose, and D-xylose as carbon sources. This species differs from all other basidiomycetous yeasts in possessing the following combination of characters: amylose production (positive), assimilation of cellobiose (positive), D-galactose (negative), myo-inositol (negative), D-mannitol (negative), and sucrose (negative).

  4. Session: Hot Dry Rock

    Energy Technology Data Exchange (ETDEWEB)

    Tennyson, George P. Jr.; Duchane, David V.; Ponden, Raymond F.; Brown, Donald W.

    1992-01-01

    This session at the Geothermal Energy Program Review X: Geothermal Energy and the Utility Market consisted of four presentations: ''Hot Dry Rock - Summary'' by George P. Tennyson, Jr.; ''HDR Opportunities and Challenges Beyond the Long Term Flow Test'' by David V. Duchane; ''Start-Up Operations at the Fenton Hill HDR Pilot Plant'' by Raymond F. Ponden; and ''Update on the Long-Term Flow Testing Program'' by Donald W. Brown.

  5. Solar assisted drying of surimi

    International Nuclear Information System (INIS)

    Solar-energy drying system appears increasingly to be attractive as commercial propositions. Surimi can be defined as a wet concentrate of muscle that is mechanically de boned; water washed and mixes with cryoprotectant for a good frozen shelf life. Facilities during surimi process and stirage such as electric power are lack in the developed countries. As a result surimi powder was introduced two decade ago. In this study surimi will be converted to powder using solar and oven dried methods. Solar drying system and oven will be used to dry surimi to less than 10%. Drying curves for surimi will be obtained in the lab

  6. Biofuels Drying Process Efficiency Research

    Directory of Open Access Journals (Sweden)

    Osvaldas Šlepikas

    2014-02-01

    Full Text Available The paper deals with biofuel drying process efficiency opportunities.Research was carried out with a special stand and performingexperiments. Experimental rig consists of an ultrasonic generator,ultrasonic transducer, a drying chamber and the humidity,temperature gauge. Tests were used for wood pellets. During theexperiment, they were irrigated with water, dried with hot air andadditionally exposed to different frequency ultrasonic vibrations.The tests results have showed that the convective drying processis combined with the ultrasonic vibrations, the drying time isreduced, which means a positive impact on the ultrasonic process.Studies have confirmed that the effectiveness of convectivedrying method combined with operating ultrasonic vibrationsincreases.

  7. In search of human-associated bacterial pathogens in Antarctic wildlife: report from six penguin colonies regularly visited by tourists.

    Science.gov (United States)

    Bonnedahl, Jonas; Broman, Tina; Waldenström, Jonas; Palmgren, Helena; Niskanen, Taina; Olsen, Björn

    2005-08-01

    We investigated the potential role of Antarctic tourism in the introduction of human-associated pathogens into Antarctic wildlife. We collected and analyzed 233 fecal samples from eight bird species. The samples were collected at six localities on the Antarctic Peninsula, which often is visited by tourists. Every sample was investigated for pathogens of potential human origin: Campylobacter jejuni, Salmonella spp., and Yersina spp. None of these bacteria was found. Our data suggest that the tourism industry so far has achieved its goal of not introducing pathogens into the Antarctic region. There is, however, an urgent need to further investigate the situation in areas closer to permanent Antarctic settlements. PMID:16201212

  8. Dry reforming of hydrocarbon feedstocks

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Yatish T. [Norfolk State University; Gardner, Todd H. [U.S. DOE

    2014-09-25

    Developments in catalyst technology for the dry reforming of hydrocarbon feedstocks are reviewed for methane, higher hydrocarbons and alcohols. Thermodynamics, mechanisms and the kinetics of dry reforming are also reviewed. The literature on Ni catalysts, bi-metallic Ni catalysts and the role of promoters on Ni catalysts is critically evaluated. The use of noble and transitional metal catalysts for dry reforming is discussed. The application of solid oxide and metal carbide catalysts to dry reforming is also evaluated. Finally, various mechanisms for catalyst deactivation are assessed. This review also examines the various process related issues associated with dry reforming such as its application and heat optimization. Novel approaches such as supercritical dry reforming and microwave assisted dry reforming are briefly expanded upon.

  9. Solar drying and agribusiness

    Directory of Open Access Journals (Sweden)

    Sebastiana del Monserrate Ruiz Cedeño

    2016-07-01

    Full Text Available Agribusinesses are the livelihoods of rural populations, but when production increase, many products are damaged and lose their commercial value due to lack of conservation treatments at a local level. Agricultural production represents the foundation of economic development of the province of Manabi. A significant level of agricultural products is lost due to lack of conservation technologies. Solar drying is a way of conserving by dehydration of some products such as: vegetables, fruits, aromatic and medicinal plants. This can be achieved by a process of proper conservation that is conducive to reduce losses using technologies easy to build, as are the different types of solar dryers which are already used in different parts of the South American region. This article proposes to introduce solar-drying technology in agricultural areas of the province of Manabi. And thereby achieve the regaining of different products that today are lost, incorporating new and attractive, marketable lines based on agricultural products naturally dehydrated with a high nutritionalvalue, capable of contributing to human health not only in the province but also in the country.

  10. Dry EEG Electrodes

    Directory of Open Access Journals (Sweden)

    M. A. Lopez-Gordo

    2014-07-01

    Full Text Available Electroencephalography (EEG emerged in the second decade of the 20th century as a technique for recording the neurophysiological response. Since then, there has been little variation in the physical principles that sustain the signal acquisition probes, otherwise called electrodes. Currently, new advances in technology have brought new unexpected fields of applications apart from the clinical, for which new aspects such as usability and gel-free operation are first order priorities. Thanks to new advances in materials and integrated electronic systems technologies, a new generation of dry electrodes has been developed to fulfill the need. In this manuscript, we review current approaches to develop dry EEG electrodes for clinical and other applications, including information about measurement methods and evaluation reports. We conclude that, although a broad and non-homogeneous diversity of approaches has been evaluated without a consensus in procedures and methodology, their performances are not far from those obtained with wet electrodes, which are considered the gold standard, thus enabling the former to be a useful tool in a variety of novel applications.

  11. Anti-inflammatory activity in selected Antarctic benthic organisms

    Directory of Open Access Journals (Sweden)

    Juan eMoles

    2014-07-01

    Full Text Available Antarctic benthos was prospected in search for anti-inflammatory activity in polar benthic invertebrates, in two different geographical areas: deep-bottoms of the Eastern Weddell Sea and shallow-waters of the South Shetland Islands. A total of 36 benthic algae and invertebrate species were selected to perform solubility tests in order to test them for anti-inflammatory activity. From these, ethanol extracts of ten species from five different phyla resulted suitable to be studied in cell macrophage cultures (RAW 264.7. Cytotoxicity (MTT method and production of inflammatory mediators (prostaglandin E2, leukotriene B4, interleukin-1 were determined at three extract concentrations (50, 125, 250 g/mL. Bioassays resulted in four different species showing anti-inflammatory activity corresponding to three sponges: Mycale (Oxymycale acerata, Isodictya erinacea, and I. toxophila; and one hemichordate: Cephalodiscus sp. These results show that Antarctic sessile invertebrates may have great value as a source of lead compounds with potential pharmaceutical applications.

  12. Study on ecological structures of coastal lakes in Antarctic continent

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Coastal region on the Antarctic continent, where it is under the influences both of ocean and ice sheet, as well as frequent human activities, could be considered as a fragile zone in Antarctic ecological environment. There are many lakes in coastal region, showing much differences from each other in physical-chemical features because of individual evolutionary history in their geographical environments, and suffering from different outside factors, such as climate changes and precipitation. Thus, it results in respective biological distribution and ecological structure in lakes. The present paper reports the results from the studies of chemical components, species distributions and community structures, which mainly consisted of planktons in lakes in the Vestfold Hills (68°38'S, 78°06'E), and the Larsemann Hills (69°30'S, 76°20'E), East Antarctica. It also treats the biological diversities and nutrient relationships of these different types of lakes. So as to provide more scientific basis for monitoring of climate changes and environmental protection in Antarctica.

  13. Snow surface microbiome on the High Antarctic Plateau (DOME C.

    Directory of Open Access Journals (Sweden)

    Luigi Michaud

    Full Text Available The cryosphere is an integral part of the global climate system and one of the major habitable ecosystems of Earth's biosphere. These permanently frozen environments harbor diverse, viable and metabolically active microbial populations that represent almost all the major phylogenetic groups. In this study, we investigated the microbial diversity in the surface snow surrounding the Concordia Research Station on the High Antarctic Plateau through a polyphasic approach, including direct prokaryotic quantification by flow cytometry and catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH, and phylogenetic identification by 16S RNA gene clone library sequencing and 454 16S amplicon pyrosequencing. Although the microbial abundance was low (<10(3 cells/ml of snowmelt, concordant results were obtained with the different techniques. The microbial community was mainly composed of members of the Alpha-proteobacteria class (e.g. Kiloniellaceae and Rhodobacteraceae, which is one of the most well-represented bacterial groups in marine habitats, Bacteroidetes (e.g. Cryomorphaceae and Flavobacteriaceae and Cyanobacteria. Based on our results, polar microorganisms could not only be considered as deposited airborne particles, but as an active component of the snowpack ecology of the High Antarctic Plateau.

  14. Antarctic environmental specimen bank. A tool for chemical monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Soggia, F.; Dalla Riva, S.; Abelmoschi, M.L.; Frache, R. [Genoa Univ., Genoa (Italy). Dipt. di Chimica e Chimica Industriale

    2000-02-01

    The work illustrates the project on Antarctic Environmental Specimen Bank (BCAA), which is an integral part of the Italian project on the micropollutants chemistry (sector on chemical contamination of the Italian Antarctic Research program, PNRA), begun in 1994 when the BCAA was installed in the department of chemistry and industrial chemistry (Genoa University, Italy). Its objective underlines an emphasis on environmental chemistry and the establishment of baselines similar to the approaches followed by the other environmental specimen banks, begun at the end of Sixties with the aim of long-term storage of representative environmental specimens in order to study the presence and the evolution of dangerous substances, but focus on the chemical characterization of samples. [Italian] Il lavoro illustra le finalita' del Progetto su una Banca Campioni Ambientali Antartici (BCAA), che e' parte integrante del progetto Chmica dei microinquinannti del Settore Contaminazione chimica del Programma Nazionale di ricerche in Antartide (ONRA), nata nel 1994 presso il dipartimento di chimicia e chimica industriale dell'universita' di Genova. A differenza di altri progetti internazionali che enfatizzano gli aspetti biologici, ecologici e medici, il progetto BCAA enfatizza la chimica ambientale.

  15. Antarctic Radio Frequency Albedo and Implications for Cosmic Ray Reconstruction

    CERN Document Server

    Besson, D Z; Sullivan, M; Allison, P; Barwick, S W; Baughman, B M; Beatty, J J; Belov, K; Bevan, S; Binns, W R; Chen, C; Chen, P; Clem, J M; Connolly, A; De Marco, D; Dowkontt, P F; DuVernois, M; Goldstein, D; Gorham, P W; Grashorn, E W; Hill, B; Hoover, S; Huang, M; Israel, M H; Javaid, A; Kowalski, J; Learned, J; Liewer, K M; Matsuno, S; Mercurio, B C; Miki, C; Mottram, M; Nam, J; Naudet, C J; Nichol, R J; Palladino, K; Romero-Wolf, A; Ruckman, L; Saltzberg, D; Seckel, D; Shang, R Y; Stockham, M; Varner, G S; Vieregg, A G; Wang, Y

    2013-01-01

    From an elevation of ~38 km, the balloon-borne ANtarctic Impulsive Transient Antenna (ANITA) is designed to detect the up-coming radio frequency (RF) signal resulting from a sub-surface neutrino-nucleon collision. Although no neutrinos have been discovered thus far, ANITA is nevertheless the only experiment to self-trigger on radio frequency emissions from cosmic-ray induced atmospheric air showers. In the majority of those cases, down-coming RF signals are observed via their reflection from the Antarctic ice sheet and back up to the ANITA interferometer. Estimating the energy scale of the incident cosmic rays therefore requires an estimate of the fractional power reflected at the air-ice interface. Similarly, inferring the energy of neutrinos interacting in-ice from observations of the upwards-directed signal refracting out to ANITA also requires consideration of signal coherence across the interface. By comparing the direct Solar RF signal intensity measured with ANITA to the surface-reflected Solar signal ...

  16. Antarctic winter mercury and ozone depletion events over sea ice

    Science.gov (United States)

    Nerentorp Mastromonaco, M.; Gårdfeldt, K.; Jourdain, B.; Abrahamsson, K.; Granfors, A.; Ahnoff, M.; Dommergue, A.; Méjean, G.; Jacobi, H.-W.

    2016-03-01

    During atmospheric mercury and ozone depletion events in the springtime in polar regions gaseous elemental mercury and ozone undergo rapid declines. Mercury is quickly transformed into oxidation products, which are subsequently removed by deposition. Here we show that such events also occur during Antarctic winter over sea ice areas, leading to additional deposition of mercury. Over four months in the Weddell Sea we measured gaseous elemental, oxidized, and particulate-bound mercury, as well as ozone in the troposphere and total and elemental mercury concentrations in snow, demonstrating a series of depletion and deposition events between July and September. The winter depletions in July were characterized by stronger correlations between mercury and ozone and larger formation of particulate-bound mercury in air compared to later spring events. It appears that light at large solar zenith angles is sufficient to initiate the photolytic formation of halogen radicals. We also propose a dark mechanism that could explain observed events in air masses coming from dark regions. Br2 that could be the main actor in dark conditions was possibly formed in high concentrations in the marine boundary layer in the dark. These high concentrations may also have caused the formation of high concentrations of CHBr3 and CH2I2 in the top layers of the Antarctic sea ice observed during winter. These new findings show that the extent of depletion events is larger than previously believed and that winter depletions result in additional deposition of mercury that could be transferred to marine and terrestrial ecosystems.

  17. Why does the Antarctic Peninsula Warm in climate simulations?

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Xin; Hall, Alex [University of California, Department of Atmospheric and Oceanic Sciences, PO BOX 951565, Los Angeles, CA (United States); Boe, Julien [University of California, Department of Atmospheric and Oceanic Sciences, PO BOX 951565, Los Angeles, CA (United States); CNRS/CERFACS, URA 1875, Toulouse (France)

    2012-03-15

    The Antarctic Peninsula has warmed significantly since the 1950s. This pronounced and isolated warming trend is collectively captured by 29 twentieth-century climate hindcasts participating in the version 3 Coupled Model Intercomparison Project. To understand the factors driving warming trends in the hindcasts, we examine trends in Peninsula region's atmospheric heat budget in every simulation. We find that atmospheric latent heat release increases in nearly all hindcasts. These increases are generally anthropogenic in origin, and account for about 60% of the ensemble-mean warming trend in the Peninsula. They are driven primarily by well-understood features of the anthropogenic intensification of global hydrological cycle. As sea surface temperature increases, moisture contained in atmospheric flows increases. When such flows are forced to ascend the Peninsula's topography, enhanced local latent heat release results. The mechanism driving the warming of the Antarctic Peninsula is therefore clear in the models. Evidence for a similar mechanism operating in the real world is seen in the increasing snow accumulation rates inferred from ice cores drilled in the Peninsula. However, the relative importance of this mechanism and other processes previously identified as potentially causing the observed warming, such as the recent sea ice retreat in the Bellingshausen Sea, is difficult to assess. Thus the relevance of the simulated warming mechanism to the observed warming is unclear, in spite of its robustness in the models. (orig.)

  18. Stratospheric column NO2 measurements from three Antarctic sites

    Science.gov (United States)

    Keys, J. G.; Johnston, P. V.

    1988-01-01

    The significance of stratospheric odd-nitrogen compounds in Antarctic ozone depletion studies has prompted an increase in Antarctic activities. Although several species are being studied, work has concentrated on the acquisition of NO2 data. Ground-based measurements of stratospheric column NO2 have been made at Arrival Heights, Antarctica, since spring 1982, with some gaps in the data base. Additional data has been acquired since February 1986 at Pole Station and Halley Bay, thus providing a chain of stations across the continent. The technique used is that of absorption spectroscopy in several wavelength regions, although here only those measurements are reported in the 430 to 450 nm region where strongly structured absorption been determined experimentally. However, theory features due to NO2 are identified in scattered sunlight in the zenith sky. Operation of a moon-tracking system at Arrival Heights has provided some additional data during the polar night. Previous analyses have shown that the NO2 column observed from the ground is strongly influenced by the season, and by the location of the site with respect to that of the polar vortex. The column amount correlates strongly with stratospheric temperature at about 70 mbar. The present data set further illustrates these features, and demonstrates both the strengths and qualifications apparent in the technique.

  19. Valley Hall Effect in Two-Dimensional Hexagonal Lattices

    Science.gov (United States)

    Yamamoto, Michihisa; Shimazaki, Yuya; Borzenets, Ivan V.; Tarucha, Seigo

    2015-12-01

    Valley is a quantum number defined for energetically degenerate but nonequivalent structures in energy bands of a crystalline material. Recent discoveries of two-dimensional (2D) layered materials have shed light on the potential use of this degree of freedom for information carriers because the valley can now be potentially manipulated in integrated 2D architectures. The valleys separated by a long distance in a momentum space are robust against external disturbance and the flow of the valley, the valley current, is nondissipative because it carries no net electronic current. Among the various 2D valley materials, graphene has by far the highest crystal quality, leading to an extremely long valley relaxation length in the bulk. In this review, we first describe the theoretical background of the valley Hall effect, which converts an electric field into a valley current. We then describe the first observation of the valley Hall effect in monolayer MoS2. Finally, we describe experiments on the generation and detection of the pure valley current in monolayer and bilayer graphene, achieved recently using the valley Hall effect and inverse valley Hall effect. While we show unambiguous evidence of a pure valley current flowing in graphene, we emphasize that the field of "valleytronics" is still in its infancy and that further theoretical and experimental investigations are necessary.

  20. Drying Spirulina with Foam Mat Drying at Medium Temperature

    OpenAIRE

    Aji Prasetyaningrum; Mohamad Djaeni

    2012-01-01

    Spirulina is a single cell blue green microalgae (Cyanobacteria) containing many Phytonutrients (Beta-carotene, Chlorophyl, Xanthophyl, Phyocianin) using as anti-carcinogen in food. Producing dry spirulina by quick drying process at medium temperature is very important to retain the Phytonutrient quality. Currently, the work is still challenging due to the gel formation that block the water diffusion from inside to the surface.  This research studies the performance of foam-mat drying on prod...

  1. Dry aging of beef; Review.

    Science.gov (United States)

    Dashdorj, Dashmaa; Tripathi, Vinay Kumar; Cho, Soohyun; Kim, Younghoon; Hwang, Inho

    2016-01-01

    The present review has mainly focused on the specific parameters including aging (aging days, temperature, relative humidity, and air flow), eating quality (flavor, tenderness and juiciness), microbiological quality and economic (shrinkage, retail yields and cost) involved beef dry aging process. Dry aging is the process where beef carcasses or primal cuts are hanged and aged for 28 to 55 d under controlling environment conditions in a refrigerated room with 0° to 4 °C and with relative humidity of 75 to 80 %. However there are various opinions on dry aging procedures and purveyors of such products are passionate about their programs. Recently, there has been an increased interest in dry aging process by a wider array of purveyors and retailers in the many countries. Dry aging process is very costly because of high aging shrinkage (6 to15 %), trims loss (3 to 24 %), risk of contamination and the requirement of highest grades meat with. The packaging in highly moisture-permeable bag may positively impact on safety, quality and shelf stability of dry aged beef. The key effect of dry aging is the concentration of the flavor that can only be described as "dry-aged beef". But the contribution of flavor compounds of proteolysis and lipolysis to the cooked dry aged beef flavor is not fully known. Also there are limited scientific studies of aging parameters on the quality and palatability of dry aged beef. PMID:27200180

  2. 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. PMID:25079555

  3. A preliminary study of trace metals and porphyrins in excreta of Gentoo penguins (Pygoscelis papua) at two locations of the Antarctic Peninsula Estudio preliminar de metales traza y porfirinas en heces de pingüinos Papua (Pygoscelis papua) en dos localidades de la península Antártica

    OpenAIRE

    Celis, J; S. Jara; D González-Acuña; Barra, R.; W Espejo

    2012-01-01

    Even though concentrations of most chemical elements in Antarctic ecosystems are very low as compared to other world's areas, their increasing time trends, as a consequence of the strong population growth and industrial development in countries of the Southern Hemisphere, could be affecting some vulnerable endemic species such as penguins. Concentrations (dry weight) of arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb) and porphyrins (copro-, uro- and proto-) were determined in feces of ...

  4. Artificial Warthog Burrows Used to Sample Adult and Immature Tsetse (Glossina spp) in the Zambezi Valley of Zimbabwe

    OpenAIRE

    Hargrove, John W.; Muzari, M. Odwell

    2015-01-01

    Background The biology of adult tsetse (Glossina spp), vectors of trypanosomiasis in Africa, has been extensively studied – but little is known about larviposition in the field. Methodology/Principal Findings In September-November 1998, in the hot-dry season in Zimbabwe’s Zambezi Valley, we used artificial warthog burrows to capture adult females as they deposited larvae. Females were subjected to ovarian dissection and were defined as perinatal flies, assumed to have entered burrows to larvi...

  5. How is water availability related to the land use and morphology of an inland valley wetland in Kenya?

    Science.gov (United States)

    Böhme, Beate; Becker, Mathias; Diekkrüger, Bernd; Förch, Gerd

    2016-06-01

    Small inland valley wetlands contribute substantially to the livelihoods of rural communities in East Africa. Their conversion into farmland is driven by water availability. We quantified spatial-temporal dynamics of water availability in a headwater wetland in the humid zone of Kenya. Climatic conditions, soil moisture contents, groundwater levels and discharge data were monitored. A land-use map and a digital elevation model of the valley bottom were created to relate variations in soil moisture to dominant land uses and valley morphology. Upland crops occupied about a third of the wetland area, while approximately a quarter of the wet, central part of the valley bottom was designated for flood-tolerant taro, grown either by itself or in association or in rotation with upland crops. Finally, natural vegetation was found in 3% of the mapped area, mainly in sections with nearpermanent soil saturation. The HBV rainfall-runoff model's overestimation of stream discharge during the long dry season of the hydrological year 2010/2011 can be explained by the strong seasonal impact of water abstraction on the wetland's water balance. Our study vividly demonstrates the necessity of multi-method approaches for assessing the impact of management practices on water availability in valley bottom wetlands in East Africa.

  6. 36Cl and 53Mn in Antarctic meteorites and 10Be-36Cl dating of Antarctic ice

    International Nuclear Information System (INIS)

    Cosmic-ray-produced 53Mn (tsub(1/2)=3.7x106 years) has been measured in twenty Antarctic meteorites by neutron activation analysis. 36Cl (tsub(1/2)=3.0x105 years) has been measured in fourteen of these objects by tandem accelerator mass spectrometry. Cosmic ray exposure ages and terrestrial ages of the meteorites are calculated from these results and from gases. 14C (tsub(1/2)=5740 years) and 26Al(tsub(1/2)=7.2x105 years) data. The terrestrial ages range from 3x104 to 5x105 years. Many of the L3-Allan Hills chrondrites seem to be a single fall based on these results. In addition, 10Be (tsub(1/2)=1.6x106 years) and 36Cl have been measured in six Antarctic ice samples. The first measurements of 10Be/36Cl ratios in the ice core samples demonstrate a new dating method for ice. (orig.)

  7. Model studies of the effects of global warming and Antarctic sea ice changes on Antarctic and global climates

    International Nuclear Information System (INIS)

    The authors discuss the results obtained in three experiments by changing the global ocean temperatures and the concentration and distribution of Antarctic sea ice in a General Circulation Model of July climate, with a view to determining the local and global impacts of Antarctic sea ice variations alone, as distinct with those coupled with global scale temperature changes which may be associated with global warming. In all cases there were significant changes in the upward flux of sensible heat over the sea ice zone associated with the reductions of sea ice. The response of weaker westerlies between 40 and 65 degree S was common to all three experiments. Their analyses suggest that a significant proportion of this is a response to the change in sea ice concentration alone. (Not surprisingly, further north of this region most of the changes induced in the wind structure in the global forcing experiment can be seen as due unambiguously to the differential changes in ocean temperatures.). This weakening of the westerlies means there is less mechanical forcing of the ocean in this region. From this they suggest that when consideration is given to the possible impact of feedbacks not considered in these experiments, sea ice changes alone, and particularly those in the Southern Hemisphere, have the potential to induce changes on a hemispheric scale

  8. The experience of the Antarctic Seismic Data Library System (SDLS) as a hub for researchers in antarctic crustal studies.

    Science.gov (United States)

    Diviacco, Paolo; Wardell, Nigel

    2010-05-01

    The SDLS was created in April 1991 under the auspices of the Scientific Committee on Antarctic Research to provide open access to Antarctic multichannel seismic-reflection data (MCS) for use in cooperative research projects. The SDLS operates under the mandates of the Antarctic Treaty System, by which all institutions that collect MCS data in Antarctica must submit their MCS data to the SDLS. The SDLS has library branches worldwide at which researchers may view and study the MCS data. MCS data are submitted to the SDLS within 4 years of collection and remain in the library under SDLS guidelines until 8 years after collection. Thereafter, the data go to World Data Centers or equivalents for unrestricted use. The SDLS offers a clearing house, based at Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS) where data are processed when needed and georeferenced, so that the end user can be provided with usable, although basic, post-stack seismic sections. Re-processing of data is beyond the scope of the SDLS, so that if a researcher is interested in reviewing pre-stack data he/she must resort to the data owner. So far 228,000 km of seismic data have been made public in all sectors of the Antarctic region. To augment the concept of physical repositories where data can be accessed by researchers travelling to one of the branches or from where data could be copied to digital media and sent to users, in 2003 it was decided to develop a web interface where data could be searched for and accessed directly. At that moment no previous non-commercial experience was available in this data field, so that the system was designed from scratch. Several technologies were introduced, tested, and after a period of use, reviewed and tuned. Particular attention was devoted to the seismic data viewing facility, which was tailored to the needs of a community with specific practices and legacies. Seismic data are sensitive data that are very important for the E&P industry, so

  9. Convective drying of sludge cake

    Science.gov (United States)

    Chen, Jianbo; Peng, Xiaofeng; Xue, Yuan; Lee, Duujong; Chu, Chingping

    2002-08-01

    This paper presented an experimental study on convective drying of waste water sludge collected from Beijing GaoBeiDian Sewage Treatment Plant, particularly on the correlation between the observed shrinkage dynamics of sludge cake and the drying curve. During the initial stage of drying the process resembles to that of a particulate bed, in which moisture diffuses and evaporates at the upper surface. Conventional drying theory assuming a diffusion-evaporating front interprets this period of drying. Consequently, owing to the very large shrinkage ratio of the dried cake, cracks emerges and propagates on and within the cake body, whence inducing evaporating channel that facilitates the water removal. This occurrence compensates the reduction of surface area for evaporation, whence extending the constant-rate period during the test. Afterwards, the cracks meet with each other and form isolated cake piles, while the subsequent drying occur mainly within these piles and the conventional theory fails. The transition between the drying on a plain cake layer and that on the isolated piles demonstrates the need to adopt distinct descriptions on these two regimes of drying for the sludge cake.

  10. Drying of a model soil

    Science.gov (United States)

    Faure, P.; Coussot, P.

    2010-09-01

    Drying experiments have been carried out with model soils made of different pastes filling granular packings. A detailed information concerning the time evolution of the water saturation distribution inside the sample was obtained from magnetic resonance imaging measurements. This study makes it possible to understand the physical origin of the drying characteristics of these materials. The drying curves exhibit a constant-rate period (CRP) and a falling-rate period (FRP) but the relative durations of these periods depend on the paste structure. With a kaolin suspension the CRP lasts down to very low water densities and is associated with a homogeneous drying of the paste throughout the sample. With a bentonite suspension the CRP is shorter and the drying in the FRP results from a complex process involving fractures progressing downward through the pasty matrix. With a gel the CRP period is even shorter and the drying in the FRP results from the progression of a dry front through the packing as a result of the shrinkage of the gel matrix. This provides an overview of the main possible processes at work when drying a soil as a function of its components along with some practical means for slowing down drying from soils.

  11. Analysis of Mining-induced Valley Closure Movements

    Science.gov (United States)

    Zhang, C.; Mitra, R.; Oh, J.; Hebblewhite, B.

    2016-05-01

    Valley closure movements have been observed for decades in Australia and overseas when underground mining occurred beneath or in close proximity to valleys and other forms of irregular topographies. Valley closure is defined as the inward movements of the valley sides towards the valley centreline. Due to the complexity of the local geology and the interplay between several geological, topographical and mining factors, the underlying mechanisms that actually cause this behaviour are not completely understood. A comprehensive programme of numerical modelling investigations has been carried out to further evaluate and quantify the influence of a number of these mining and geological factors and their inter-relationships. The factors investigated in this paper include longwall positional factors, horizontal stress, panel width, depth of cover and geological structures around the valley. It is found that mining in a series passing beneath the valley dramatically increases valley closure, and mining parallel to valley induces much more closure than other mining orientations. The redistribution of horizontal stress and influence of mining activity have also been recognised as important factors promoting valley closure, and the effect of geological structure around the valley is found to be relatively small. This paper provides further insight into both the valley closure mechanisms and how these mechanisms should be considered in valley closure prediction models.

  12. Comparative recruitment success of pine provenances (Pinus sylvestris, Pinus nigra) under simulated climate change in the Swiss Rhone valley

    Science.gov (United States)

    Richter, Sarah; Moser, Barbara; Ghazoul, Jaboury; Wohlgemuth, Thomas

    2010-05-01

    Low elevation Scots pine forests of European inner-alpine dry valleys may potentially disappear under continued climate warming, largely in response to increased warming and drought effects. In the upper Rhone valley, the driest region in Switzerland, increased Scots pine mortality in mature forest stands and sparse tree establishment after a large-scale forest fire already give evidence for ongoing climate change. Furthermore, vegetation models predict a decline of Scots pine (Pinus sylvestris) and Pubescent oak (Quercus pubescens) even under a moderate temperature increase of 2-3°C. A decline of tree species in the region may lead to a transition from forest to a steppe-like vegetation. Such a change is of considerable concern for both biodiversity and natural hazard protection. Although changing climate conditions affect all life stages of a tree, its most vulnerable stage is recruitment. We tested P. sylvestris and P. nigra seedlings to simulated temperature increase and water stress, using seeds from the upper Rhone valley, Switzerland (CH), and from Peñyagolosa, Spain (ES). The experiment was located outdoors at the bottom of the Rhone Valley. Treatments consisted of factorial combinations of 3 precipitation regimes (‘wet spring-wet summer', ‘dry spring-dry summer' and ‘wet spring-dry summer') and 3 soil heating levels (+0 °C, +2.5 °C, +5 °C). Automatically operated shelters intercepted natural rainfall and different precipitation regimes were simulated by manual irrigation. We found significantly lower germination rates under dry conditions compared to wet conditions, whereas soil temperature affected germination rates only for P. nigra and when elevated by 5°C. Contrastingly, an increase of soil temperatures by 2.5 °C already caused a substantial decrease of survival rates under both ‘dry spring-dry summer' and ‘wet spring-dry summer' conditions. Precipitation regime was more important for survival than temperature increase. Seasonality of

  13. Advanced dry and dry--wet cooling towers

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, B. M.

    1977-09-01

    Although progressive restrictions on the use of fresh water for power plant cooling and the growing use of dry cooling is anticipated in many regions of the country, the transition to this form of cooling will occur slowly unless improved technology leads to lower cost systems. The need for supplemental power during periods of warm weather contribute to the high cost of dry cooling and have led to greater emphasis on combined dry and wet cooling. Experimental and demonstration programs are underway at several locations in the U.S. to develop new systems which will hopefully reduce the cost of dry and wet/dry systems and/or the need for supplemental power. If any of the projected improvements of these advanced systems can be developed to the point of commercial availability, the use of dry cooling would be greatly increased and many of the secondary benefits will be realized. These include greater freedom to take advantage of existing transmission corridors, multiple plants on presently water-limited sites and mine mount sites in water-limited regions. The more promising advanced concepts under study are reviewed and appraised as to their likelihood of having a significant impact on the future use of dry (including dry/wet) cooling.

  14. Drying Spirulina with Foam Mat Drying at Medium Temperature

    Directory of Open Access Journals (Sweden)

    Aji Prasetyaningrum

    2012-10-01

    Full Text Available Spirulina is a single cell blue green microalgae (Cyanobacteria containing many Phytonutrients (Beta-carotene, Chlorophyl, Xanthophyl, Phyocianin using as anti-carcinogen in food. Producing dry spirulina by quick drying process at medium temperature is very important to retain the Phytonutrient quality. Currently, the work is still challenging due to the gel formation that block the water diffusion from inside to the surface.  This research studies the performance of foam-mat drying on production of dry spirulina. In this method the spirulina was mixed with foaming agent (glair/egg albumen, popular as white egg at 2.5% by weight at air velocity 2.2 m/sec. Here, the effect of spirulina thickness and operational temperature on drying time and quality (Beta-carotene and color were observed. The drying time was estimated based on the measurement of water content in spirulina versus time. Result showed that the thicker spirulina, the longer drying time. Conversely, the higher operational temperature, faster drying time. At thickness ranging 1-3 mm and operational temperature below 70oC, the quality of spirulina can fit the market requirement

  15. Quality assurance of the solar UV network in the Antarctic

    Science.gov (United States)

    Lakkala, K.; Redondas, A.; Meinander, O.; Torres, C.; Koskela, T.; Cuevas, E.; Taalas, P.; Dahlback, A.; Deferrari, G.; Edvardsen, K.; Ochoa, H.

    2005-08-01

    Measuring ultraviolet radiation in the Antarctic region, where weather conditions are extremely challenging, is a demanding task. Proper quality control of the measurements and quality assurance of the data, which are the basis of all scientific use of data, has to be especially well planned and executed. In this paper we show the importance of proper quality assurance and describe the methods used to successfully operate the NILU-UV multichannel radiometers of the Antarctic network stations at Ushuaia, 54°S, and Marambio, 64°S. According to our experience, even though multichannel instruments are supposed to be rather stable as a function of time, severe drifts can occur in the sensitivity of the channels under these harsh conditions. During 2000-2003 the biggest drifts were 35%, both at Ushuaia and Marambio, with the sensitivity of the channels dropping at different rates. Without proper corrections in the data, this would have seriously affected the calculated UV dose rates. As part of the quality assurance of the network a traveling reference NILU-UV, which was found to be stable, was used to transfer the desired irradiance scale to the site NILU-UV data. Relative lamp tests were used to monitor the stability of the instruments. Each site NILU-UV was scaled channel by channel to the traveling reference by performing solar comparisons. The method of scaling each channel separately was found to be successful, even though the differences between the raw data of the site NILU-UV and the reference instruments were, before the data correction, as much as 40%. After the correction, the mean ratios of erythemally weighted UV dose rates measured during the solar comparisons in 2000-2003 between the reference NILU-UV and the site NILU-UV were 1.007 +/- 0.011 and 1.012 +/- 0.012 for Ushuaia and Marambio, respectively, when the solar zenith angle varied up to 80°. These results make possible the scientific use of NILU-UV data measured simultaneously at quite different

  16. A Maturing Tephra Record in the West Antarctic Ice Sheet

    Science.gov (United States)

    Dunbar, N. W.; Kurbatov, A.; McIntosh, W. C.

    2011-12-01

    Tephra layers found in many Antarctic ice cores range from sub-centimeter thick, visible layers to cryptotephra consisting of sparse, fine-grained (Takahe, tephra from which have also been recognized in the marine record (Hillenbrand et al., 1988). A well-defined ash layer is found at a depth of between 190.37-190.39 m depth in the WAIS Divide core, containing 20 um ash shards that are chemically correlated to the the Pleaides volcanoes, in northern Victoria Land. This tephra layer correlates to one found in a Siple Dome (B) ice core (97.2 to 97.7 m depth) and in the Taylor Dome ice core (79.2 m depth). Deeper parts of the WAIS Divide ice core correspond to a time interval of abundant regional volcanism, represented by the large number of visible dust bands and cloudy layers in the core (A. Orsi, pers. comm., 2010). A distinct "visible brown layer" at a depth of 1586.363 m. (8.279 Ky BP preliminary age) is very likely to be from a major eruption of the West Antarctic volcano Mt. Takahe (8.2±5.4 , Wilch et al., 1999). This layer is found at a depth of 503.58-503.87 m in the Siple Dome A core (SMDA) corresponding to 8.167-8.181 Ky before 1950, and almost certainly to a visible layer identified and analyzed in the Byrd ice core at 788 m (Palais et al., 1988). A visible double layer at 1741.246 m (9.57 KyBP preliminary age) may correspond to a very distinct tephra layer in the SDMA core at a depth of around 550 m (corresponding to an age of around 9.7 Ky before 1950). This layer is derived from the West Antarctic stratovolcano, Mt. Berlin. In the segment of WAIS Divide ice core between 2251 and 2557 m depth (15.2 to 20.6 preliminary age), numerous dust bands and cloudy layers are reported in the ice. This corresponds to the age of ice in the Byrd Core that contained many volcanic layers (Gow and Williamson, 1971), and also an interval in the SDMA where numerous distinct tephra layers associated with highly explosive eruptions of Mt. Berlin were found. Detailed

  17. Potential genesis and implications of calcium nitrate in Antarctic snow

    Science.gov (United States)

    Mahalinganathan, Kanthanathan; Thamban, Meloth

    2016-04-01

    Among the large variety of particulates in the atmosphere, calcic mineral dust particles have highly reactive surfaces that undergo heterogeneous reactions with atmospheric acids contiguously. The association between nssCa2+, an important proxy indicator of mineral dust, and NO3-, a dominant anion in the Antarctic snowpack, was analysed. A total of 41 snow cores ( ˜ 1 m each) that represent snow deposited during 2008-2009 were studied along coastal-inland transects from two different regions in East Antarctica - the Princess Elizabeth Land (PEL) and central Dronning Maud Land (cDML). Correlation statistics showed a strong association (at 99 % significance level) between NO3- and nssCa2+ at the near-coastal sections of both PEL (r = 0.74) and cDML (r = 0.82) transects. Similarly, a strong association between these ions was also observed in snow deposits at the inland sections of PEL (r = 0.73) and cDML (r = 0.84). Such systematic associations between nssCa2+ and NO3- are attributed to the interaction between calcic mineral dust and nitric acid in the atmosphere, leading to the formation of calcium nitrate (Ca(NO3)2) aerosol. Principal component analysis revealed common transport and depositional processes for nssCa2+ and NO3- both in PEL and cDML. Forward- and back-trajectory analyses using HYSPLIT model v. 4 revealed that southern South America (SSA) was an important dust-emitting source to the study region, aided by the westerlies. Particle size distribution showed that over 90 % of the dust was in the range < 4 µm, indicating that these dust particles reached the Antarctic region via long-range transport from the SSA region. We propose that the association between nssCa2+ and NO3- occurs during the long-range transport due to the formation of Ca(NO3)2 rather than to local neutralisation processes. However, the influence of local dust sources from the nunataks in cDML and the contribution of high sea salt in coastal PEL evidently mask such association in the

  18. Variability of Antarctic Sea Ice 1979-1998

    Science.gov (United States)

    Zwally, H. Jay; Comiso, Josefino C.; Parkinson, Claire L.; Cavalieri, Donald J.; Gloersen, Per; Koblinsky, Chester J. (Technical Monitor)

    2001-01-01

    The principal characteristics of the variability of Antarctic sea ice cover as previously described from satellite passive-microwave observations are also evident in a systematically-calibrated and analyzed data set for 20.2 years (1979-1998). The total Antarctic sea ice extent (concentration > 15 %) increased by 13,440 +/- 4180 sq km/year (+1.18 +/- 0.37%/decade). The area of sea ice within the extent boundary increased by 16,960 +/- 3,840 sq km/year (+1.96 +/- 0.44%/decade). Regionally, the trends in extent are positive in the Weddell Sea (1.5 +/- 0.9%/decade), Pacific Ocean (2.4 +/- 1.4%/decade), and Ross (6.9 +/- 1.1 %/decade) sectors, slightly negative in the Indian Ocean (-1.5 +/- 1.8%/decade, and strongly negative in the Bellingshausen-Amundsen Seas sector (-9.5 +/- 1.5%/decade). For the entire ice pack, small ice increases occur in all seasons with the largest increase during autumn. On a regional basis, the trends differ season to season. During summer and fall, the trends are positive or near zero in all sectors except the Bellingshausen-Amundsen Seas sector. During winter and spring, the trends are negative or near zero in all sectors except the Ross Sea, which has positive trends in all seasons. Components of interannual variability with periods of about 3 to 5 years are regionally large, but tend to counterbalance each other in the total ice pack. The interannual variability of the annual mean sea-ice extent is only 1.6% overall, compared to 5% to 9% in each of five regional sectors. Analysis of the relation between regional sea ice extents and spatially-averaged surface temperatures over the ice pack gives an overall sensitivity between winter ice cover and temperature of -0.7% change in sea ice extent per K. For summer, some regional ice extents vary positively with temperature and others negatively. The observed increase in Antarctic sea ice cover is counter to the observed decreases in the Arctic. It is also qualitatively consistent with the

  19. The lakes of the Jordan Rift Valley

    International Nuclear Information System (INIS)

    This paper presents a summary of the proceedings of a workshop on the Lakes of the Jordan Rift Valley that was held in conjunction with the CRP on The Use of Isotope Techniques in Lake Dynamics Investigations. The paper presents a review of the geological, hydrogeological and physical limnological setting of the lakes in the Jordan Rift Valley, Lake Hula, Lake Kinneret and the Dead Sea. This is complemented by a description of the isotope hydrology of the system that includes the use of a wide range of isotopes: oxygen-18, deuterium, tritium, carbon-14, carbon-13, chlorine isotopes, boron-11 and helium-3/4. Environmental isotope aspects of the salt balances of the lakes, their palaeolimnology and biogeochemical tracers are also presented. The scope of application of isotopic tracers is very broad and provides a clear insight into many aspects of the physical, chemical and biological limnology of the Rift Valley Lakes. (author)

  20. Generalized drying curves in conductive/convective paper drying

    Directory of Open Access Journals (Sweden)

    O.C. Motta Lima

    2000-12-01

    Full Text Available This work presents a study related to conductive/convective drying of paper (cellulose sheets over heated surfaces, under natural and forced air conditions. The experimental apparatus consists in a metallic box heated by a thermostatic bath containing an upper surface on which the paper samples (about 1 mm thick are placed. The system is submitted to ambient air under two different conditions: natural convection and forced convection provide by an adjustable blower. The influence of initial paper moisture content, drying (heated surface temperature and air velocity on drying curves behavior is observed under different drying conditions. Hence, these influence is studied through the proposal of generalized drying curves. Those curves are analyzed individually for each air condition exposed above and for both together. A set of equations to fit them is proposed and discussed.

  1. Stably Stratified Flow in a Shallow Valley

    Science.gov (United States)

    Mahrt, L.

    2016-07-01

    Stratified nocturnal flow above and within a small valley of approximately 12-m depth and a few hundred metres width is examined as a case study, based on a network of 20 sonic anemometers and a central 20-m tower with eight levels of sonic anemometers. Several regimes of stratified flow over gentle topography are conceptually defined for organizing the data analysis and comparing with the existing literature. In our case study, a marginal cold pool forms within the shallow valley in the early evening but yields to larger ambient wind speeds after a few hours, corresponding to stratified terrain-following flow where the flow outside the valley descends to the valley floor. The terrain-following flow lasts about 10 h and then undergoes transition to an intermittent marginal cold pool towards the end of the night when the larger-scale flow collapses. During this 10-h period, the stratified terrain-following flow is characterized by a three-layer structure, consisting of a thin surface boundary layer of a few metres depth on the valley floor, a deeper boundary layer corresponding to the larger-scale flow, and an intermediate transition layer with significant wind-directional shear and possible advection of lee turbulence that is generated even for the gentle topography of our study. The flow in the valley is often modulated by oscillations with a typical period of 10 min. Cold events with smaller turbulent intensity and duration of tens of minutes move through the observational domain throughout the terrain-following period. One of these events is examined in detail.

  2. Market opportunities for solar drying

    International Nuclear Information System (INIS)

    One of the most promising applications for solar heating is the drying of agricultural products. The drying of agricultural products requires large quantities of low temperature air, in many cases, on a year-round basis. Low cost air-based collectors can provide heated air at solar collection efficiencies of 30 to 70%. In 1998/1999 a study was commissioned to better understand the technical and economic potential for solar drying of agricultural products in the world. The practical potential for solar drying was then determined for 59 crops and 22 regions. The world market for solar drying can be divided into three market segments: 1) mechanical drying T50 deg. C; 3) sun drying. The most promising market for solar drying is generally market segment 1. For this segment the potential amount of energy displaced by solar is in between 216 770 PJ (World-wide). For Western Europe this potential is estimated between 23 88 PJ and for Eastern Europe between 7 and 13 PJ. A different market introduction strategy is required for each market segment. A total of 13 combinations of crops and regions are selected that appear to have the highest practical potential for solar drying. In the Netherlands a programme of activities was carried out by Ecofys and other organisations, to identify and develop the market potential for solar (assisted) drying of agricultural products. A promotional campaign for the use of renewable energy in the (promising) flower bulb sector is planned on a short-term basis to speed up market developments. It can be concluded that there is a large market for solar drying in the World as well as in Europe. (au)

  3. Hidden Tales of the Bujang Valley

    OpenAIRE

    Maznah Wan Omar; Syakirah Mohammed; Razanawati Nordin; Alauyah Johari; Syazliyati Ibrahim

    2010-01-01

    Legends thrive, but there is little tangible evidence about dozens of Malay kingdoms, which are said to have flourished long before the emergence of Melaka in the late 14th century. The Bujang Valley in South Kedah, for one, is Malaysia’s richest archaeological site. The valley is the guardian of countless hidden tales which are waiting to be unveiled. Here, the beliefs of the Malay ancestors were centred upon nature and the spirits which permeate every aspect of their lives. These beliefs ha...

  4. Measured compaction for 24 extensometers in the Central Valley

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This digital dataset contains the compaction data for 24 extensometers used for observations in the Central Valley Hydrologic Model (CVHM). The Central Valley...

  5. Goldstone-Apple Valley Radio Telescope System Theory of Operation

    Science.gov (United States)

    Stephan, George R.

    1997-01-01

    The purpose of this learning module is to enable learners to describe how the Goldstone-Apple Valley Radio Telescope (GAVRT) system functions in support of Apple Valley Science and Technology Center's (AVSTC) client schools' radio astronomy activities.

  6. Evapotranspiration Input Data for the Central Valley Hydrologic Model (CVHM)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This digital dataset contains monthly reference evapotranspiration (ETo) data for the Central Valley Hydrologic Model (CVHM). The Central Valley encompasses an...

  7. Is It Flu, or Is It Valley Fever?

    Science.gov (United States)

    ... https://medlineplus.gov/news/fullstory_160138.html Is It Flu, or Is It Valley Fever? Potentially fatal infection is found in ... often-overlooked infection, and about 160 die from it, the society says. "Valley fever is underdiagnosed in ...

  8. Dry wall Kras 2011

    Directory of Open Access Journals (Sweden)

    Domen Zupančič

    2012-01-01

    Full Text Available Despite the modesty of hiska, they show a simple understanding of corbelling technique. One could say they are all examples of human landscape cultivation. Although there is no evident common line when comparing all types of hiska, the cunning eye may observe one shared feature: the positioning of the entrance. More or less all the documented shelters have south or south-western facing entrances. The burja is a cold northerly wind; from the south (Adriatic Sea the winds are warmer. When resting, the setting sun is taken as a sign of the ending of the working day and a reward for the whole day’s efforts. Entrances are the only openings to these structures, and they should serve as well as possible - to watch over the crops, to wait when hunting, to enjoy the calm of evening light, to breathe the sea wind.The syntax of the architectural language of layering stone and shaping the pattern of the landscape remain an inventive realisation of spatial ideas from the past until today. Not only ideas of shaping space - these ideas are basic interventions in the natural habitat which contribute to survival. Culture and an awareness of its values are the origins of local development and reasonable heritage preservation. The next step are tutorial days with workshops on how to build dry stone structures, walls and other stone architecture, as the DSWA organisation in the UK is doing.

  9. Sessile nanofluid droplet drying.

    Science.gov (United States)

    Zhong, Xin; Crivoi, Alexandru; Duan, Fei

    2015-03-01

    Nanofluid droplet evaporation has gained much audience nowadays due to its wide applications in painting, coating, surface patterning, particle deposition, etc. This paper reviews the drying progress and deposition formation from the evaporative sessile droplets with the suspended insoluble solutes, especially nanoparticles. The main content covers the evaporation fundamental, the particle self-assembly, and deposition patterns in sessile nanofluid droplet. Both experimental and theoretical studies are presented. The effects of the type, concentration and size of nanoparticles on the spreading and evaporative dynamics are elucidated at first, serving the basis for the understanding of particle motion and deposition process which are introduced afterward. Stressing on particle assembly and production of desirable residue patterns, we express abundant experimental interventions, various types of deposits, and the effects on nanoparticle deposition. The review ends with the introduction of theoretical investigations, including the Navier-Stokes equations in terms of solutions, the Diffusion Limited Aggregation approach, the Kinetic Monte Carlo method, and the Dynamical Density Functional Theory. Nanoparticles have shown great influences in spreading, evaporation rate, evaporation regime, fluid flow and pattern formation of sessile droplets. Under different experimental conditions, various deposition patterns can be formed. The existing theoretical approaches are able to predict fluid dynamics, particle motion and deposition patterns in the particular cases. On the basis of further understanding of the effects of fluid dynamics and particle motion, the desirable patterns can be obtained with appropriate experimental regulations. PMID:25578408

  10. Does the Antarctic ozone hole have a future?

    Science.gov (United States)

    Singer, S. Fred

    1988-11-01

    In spite of recent discoveries related to the mechanism of the Antarctic ozone hole (AOH), we do not as yet have a sufficient scientific base to answer important policy questions: is the AOH a completely new phenomenon, or is it are current one? Is it produced by human activities? And what can and should be done about it? I suggest here a hypothesis concerning the cause of the AOH, which may provide at least partial answers.The AOH is more than a scientific curiosity. Its dramatic discovery in 1985 raised fears about the fate of global ozone and provided the impetus for an international effort to limit and roll back the worldwide production of chlorofluorocarbons (CFCs), synthetic chemicals widely used in refrigeration and industrial processes.

  11. Emergence of healing in the Antarctic ozone layer

    Science.gov (United States)

    Solomon, Susan; Ivy, Diane J.; Kinnison, Doug; Mills, Michael J.; Neely, Ryan R.; Schmidt, Anja

    2016-07-01

    Industrial chlorofluorocarbons that cause ozone depletion have been phased out under the Montreal Protocol. A chemically driven increase in polar ozone (or “healing”) is expected in response to this historic agreement. Observations and model calculations together indicate that healing of the Antarctic ozone layer has now begun to occur during the month of September. Fingerprints of September healing since 2000 include (i) increases in ozone column amounts, (ii) changes in the vertical profile of ozone concentration, and (iii) decreases in the areal extent of the ozone hole. Along with chemistry, dynamical and temperature changes have contributed to the healing but could represent feedbacks to chemistry. Volcanic eruptions have episodically interfered with healing, particularly during 2015, when a record October ozone hole occurred after the Calbuco eruption.

  12. Soil water repellency of Antarctic soils (Elephant Point). First results

    Science.gov (United States)

    Pereira, Paulo; Oliva, Marc; Ruiz Fernández, Jesus

    2015-04-01

    Hydrophobicity it is a natural properties of many soils around the world. Despite the large body of research about soil water hydrophobicity (SWR) in many environments, little information it is available about Antarctic soils and their hydro-geomorphological consequences. According to our knowledge, no previous work was carried out on this environment. Soil samples were collected in the top-soil (0-5 cm) and SWR was analysed according to the water drop penetration test. The preliminary results showed that all the soils collected were hydrophilic, however further research should be carried out in order to understand if SWR changes with soil depth and if have implications on soil infiltration during the summer season.

  13. Antarctic Wave Dynamics Mystery Discovered by Lidar, Radar and Imager

    Science.gov (United States)

    Chen, Cao; Chu, Xinzhao; Fong, Weichun; Lu, Xian; McDonald, Adrian J.; Pautet, Dominique; Taylor, Mike

    2016-06-01

    Since the start of the McMurdo Fe lidar campaign, largeamplitude (~±30 K), long-period (4 to 9 h) waves with upward energy propagating signatures are frequently observed in the MLT temperatures. Despite its frequent appearance, such type of wave was neither widely observed nor well understood in the past. At McMurdo (77.8°S, 166.7°E), the simultaneous observations of such waves using lidar, radar and airglow imager can provide 3-D intrinsic wave-propagation properties, which are greatly needed for understanding their sources and potential impacts. This study presents the first coincident observation of these 4-9 h waves by lidar, radar and airglow imager in the Antarctic mesopause region.

  14. Determination of Antarctic geoid by using global gravity field

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    With Chinese latest global gravity field model WDM94, the authors providethe geoid height and mean free-air gravity anomaly of Antarctica (The range of latitude is from—60° to—90°). In order to conclude and analyze the characters of Antarctic geoid roundly, the authors collect the latest oversea global gravity field model OSU91 (to degree and order 360) and JGMOSU (to degree and order 360), get the corresponding geoid height and mean free-air gravity anomaly. The results arecompared with the results got from WDM94, thus we get the difference. The standard deviation of geoid height between WDM94 and OSU91 is ± 1.90 re;the deviation of geoid between WDM9 and JGMOSU is ± 2.09 m. The standard deviation of mean gravity anomaly are±8.97 mGal and ± 9.32 mGal respectively.

  15. Antarctic Tephrochronology: A Maturing Record of Visible Layers and Cryptotephra

    Science.gov (United States)

    Dunbar, N. W.; Kurbatov, A.; McIntosh, W. C.

    2012-12-01

    Visible tephra layers, which represent important time-stratigraphic markers in ice-bound climate records, have been found in majority of the deep Antarctic ice cores. Ice core tephra layers range from sub-centimeter thick, visible layers to cryptotephra consisting of sparse, fine-grained (Takahe, tephra from which have also been recognized in the marine record (Hillenbrand et al., 1988). However, a well-defined ash layer recognized at a depth of between 190.37-190.39 m depth in the WDC06A core and several other ice cores, which contains 20 μm ash shards, was chemically characterized as being derived from the East Antarctic Pleiades volcanic center. Several tephra layers, including one that correlates between the SDMA and WDC06A cores, are thought to be related to South American volcanism. In terms of the West Antarctic regional tephra framework, a very distinct "visible brown layer", with glass shards up to 20 μm in diameter, found at a depth of 1586.363 m in WDC06A (8.279 ka B.P. preliminary age), chemically correlates to a major 40Ar/39Ar-dated (8.2±5.4) eruption of the West Antarctic volcano Mt. Takahe. This layer is also observed at a depth of between 503.58 and 503.87 m in the SMDA core, corresponding to ages between 8.167 and 8.181 ka B.P. (Dunbar and Kurbatov, 2011). A layer almost certainly corresponding to this one was also identified and analyzed in the Byrd ice core at a depth of 788 m (Palais et al., 1988). A tephra layer at a depth of 2441.95 m in WDC06A chemically correlates to a layer in SDMA at a depth of 707.00 m. This layer correlates to an eruption of Mt. Berlin which has been dated using 40Ar/39Ar at 18.2±5.8 ka B.P. Several other tephra layers from Mt. Berlin have been identified in the WDC06A and SDMA ice cores. Finally, a tephra layer with a grain size of between 100 and 200 microns, very coarse by ice core standards, has been identified at a depth of 2569.205 m depth in the WDC06A core. The grain size, morphology and composition of this

  16. Quasi-biennial modulation of the Antarctic ozone depletion

    Science.gov (United States)

    Lait, Leslie R.; Schoeberl, Mark R.; Newman, Paul A.

    1989-01-01

    The quasi-biennial oscillation (QBO) in total ozone and temperature has been extracted from 9 years of Total Ozone Mapping Spectrometer (TOMS) observations and National Meteorological Center (NMC) analyses. Years in which QBO-related variations in the total ozone and temperature are positive are found to correspond to years with smaller September Antarctic total ozone hole decline rates and vice versa. The QBO appears to be responsible for September decline rate deviations up to 0.4 Dobson units (DU) per day. Also, the QBO at mid-latitudes appears to be better correlated with the 30-mbar tropical QBO winds than with those at 50 mbar. Possible mechanisms that would explain these phenomena are discussed.

  17. Curation and Allocation of the New Antarctic Nakhlite, MIL03346

    Science.gov (United States)

    McBride, K. M.; Righter, K.; Satterwhite, C. E.; Schwarz, C.; Robinson, P.

    2005-01-01

    In January 2004, the ANSMET reconnaissance field team (Fig. 1) working in the Miller Range of the Transantarctic Mountains discovered a 715 g achondrite that was instantly recognized as unique. Named MIL03346, initial processing (NASA Johnson Space Center or JSC) and classification (Smithsonian Institution or SI) revealed this achondrite to be a nakhlite (Fig. 2). MIL03346 is the seventh nakhlite recognized in world collections [2], the third nakhlite returned from Antartica, and the first nakhlite in the US Antarctic collection (Table 1). The following is a summary of the steps taken in the processing and allocating of MIL 03346 and some comparisons to some other lunar and martian meteorites processed and allocated at JSC.

  18. Emergence of healing in the Antarctic ozone layer.

    Science.gov (United States)

    Solomon, Susan; Ivy, Diane J; Kinnison, Doug; Mills, Michael J; Neely, Ryan R; Schmidt, Anja

    2016-07-15

    Industrial chlorofluorocarbons that cause ozone depletion have been phased out under the Montreal Protocol. A chemically driven increase in polar ozone (or "healing") is expected in response to this historic agreement. Observations and model calculations together indicate that healing of the Antarctic ozone layer has now begun to occur during the month of September. Fingerprints of September healing since 2000 include (i) increases in ozone column amounts, (ii) changes in the vertical profile of ozone concentration, and (iii) decreases in the areal extent of the ozone hole. Along with chemistry, dynamical and temperature changes have contributed to the healing but could represent feedbacks to chemistry. Volcanic eruptions have episodically interfered with healing, particularly during 2015, when a record October ozone hole occurred after the Calbuco eruption. PMID:27365314

  19. Ocean forcing of glacier retreat in the western Antarctic Peninsula.

    Science.gov (United States)

    Cook, A J; Holland, P R; Meredith, M P; Murray, T; Luckman, A; Vaughan, D G

    2016-07-15

    In recent decades, hundreds of glaciers draining the Antarctic Peninsula (63° to 70°S) have undergone systematic and progressive change. These changes are widely attributed to rapid increases in regional surface air temperature, but it is now clear that this cannot be the sole driver. Here, we identify a strong correspondence between mid-depth ocean temperatures and glacier-front changes along the ~1000-kilometer western coastline. In the south, glaciers that terminate in warm Circumpolar Deep Water have undergone considerable retreat, whereas those in the far northwest, which terminate in cooler waters, have not. Furthermore, a mid-ocean warming since the 1990s in the south is coincident with widespread acceleration of glacier retreat. We conclude that changes in ocean-induced melting are the primary cause of retreat for glaciers in this region. PMID:27418507

  20. Quality changes of Antarctic krill powder during long term storage

    DEFF Research Database (Denmark)

    Nielsen, Nina Skall; Lu, Henna Fung Sieng; Bruheim, Inge;

    2016-01-01

    Krill is a valuable sustainable resource of omega-3 fatty acids and protein, which may be processed into a krill powder for human consumption. The objective of this study was to investigate the stability of krill powder when stored for up to 12 months at room temperature. In addition, the effect...... and a concomitant decrease in antioxidants, tocopherol, and astaxanthin was observed. In addition, there was a minor decrease in phospholipids and n-3 fatty acids; however, storage at vacuum improved the oxidative stability of krill powder. Practical applications: For the use of krill powder in human nutrition......, it is important, that the quality and stability is sufficiently high to retain the nutritional value during storage. This study contributes with information about the stability during storage up to 12 months at room temperature and the effect of packaging the powder in vacuum. Antarctic krill (Euphausia superba...