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Sample records for dry valleys antarctica

  1. 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.

  2. Soil and landform interplay in the dry valley of Edson Hills, Ellsworth Mountains, continental Antarctica

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    Delpupo, Caroline; Schaefer, Carlos Ernesto Gonçalves Reynaud; Roque, Mariane Batalha; de Faria, André Luiz Lopes; da Rosa, Katia Kellem; Thomazini, André; de Paula, Mayara Daher

    2017-10-01

    The main relief units from the dry valley of Edson Hills, Ellsworth Mountains, Antarctica (79°49‧12.4″/83°40‧16.1″), were assessed, emphasizing the analysis of soil and landform interplay. Soil morphological, physical, and chemical properties; salinity; surface boulder weathering (frequency and feature); classification; and weathering stages were analyzed. Three distinct landforms summarize the geomorphology of the dry valley of Edson Hills, Ellsworth Mountains: (i) periglacial features like slightly creeping debris-mantled slopes, steep debris-mantled slopes, patterned grounds, and thermokarst; (ii) glacial features like hummocky moraines, lateral moraines (supraglacial), lakes, kettle hole (proglacial), cirques infill (subglacial), horn, and arête (erosional glacial); and (iii) nonglacial features like scree slopes and talus deposits. All these glacial and periglacial features are related to the West Antarctica ice sheet variations. Soils in the dry valley of Edson Hills are pedologically poorly developed. However, the degree of development in soils associated with patterned ground and moraine systems is remarkable. All soils present desert pavement owing to the action of severe aeolian erosion. In addition, soils accumulate salts depending on the local drainage conditions. The most expressive soil classes among the studied soils were Typic Haploturbel and Typic Anhyorthel, especially because of: (i) a general trend of ice-cemented permafrost occurrence in lower portions of the landscape, particularly in the patterned ground area and in the hummocky moraine; and (ii) the presence of dry permafrost in higher positions of the landscape, in relief units such as in debris-mantled slopes and talus deposits. Thus, a close relationship among soil characteristics and landforms were observed in the dry valley of Edson Hills.

  3. Inland diatoms from the McMurdo Dry Valleys and James Ross Island, Antarctica

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    Esposito, R.M.M.; Spaulding, S.A.; McKnight, Diane M.; Van De Vijver, B.; Kopalova, K.; Lubinski, D.; Hall, B.; Whittaker, T.

    2008-01-01

    Diatom taxa present in the inland streams and lakes of the McMurdo Dry Valleys and James Ross Island, Antarctica, are presented in this paper. A total of nine taxa are illustrated, with descriptions of four new species (Luticola austroatlantica sp. nov., Luticola dolia sp. nov., Luticola laeta sp. nov., Muelleria supra sp. nov.). In the perennially ice-covered lakes of the McMurdo Dry Valleys, diatoms are confined to benthic mats within the photic zone. In streams, diatoms are attached to benthic surfaces and within the microbial mat matrix. One species, L. austroatlantica, is found on James Ross Island, of the southern Atlantic archipelago, and the McMurdo Dry Valleys. The McMurdo Dry Valley populations are at the lower range of the size spectrum for the species. Streams flow for 6-10 weeks during the austral summer, when temperatures and solar radiation allow glacial ice to melt. The diatom flora of the region is characterized by species assemblages favored under harsh conditions, with naviculoid taxa as the dominant group and several major diatom groups conspicuously absent. ?? 2008 NRC.

  4. Taxonomic and Functional Diversity of Soil and Hypolithic Microbial Communities in Miers Valley, McMurdo Dry Valleys, Antarctica

    Science.gov (United States)

    Wei, Sean T. S.; Lacap-Bugler, Donnabella C.; Lau, Maggie C. Y.; Caruso, Tancredi; Rao, Subramanya; de los Rios, Asunción; Archer, Stephen K.; Chiu, Jill M. Y.; Higgins, Colleen; Van Nostrand, Joy D.; Zhou, Jizhong; Hopkins, David W.; Pointing, Stephen B.

    2016-01-01

    The McMurdo Dry Valleys of Antarctica are an extreme polar desert. Mineral soils support subsurface microbial communities and translucent rocks support development of hypolithic communities on ventral surfaces in soil contact. Despite significant research attention, relatively little is known about taxonomic and functional diversity or their inter-relationships. Here we report a combined diversity and functional interrogation for soil and hypoliths of the Miers Valley in the McMurdo Dry Valleys of Antarctica. The study employed 16S rRNA fingerprinting and high throughput sequencing combined with the GeoChip functional microarray. The soil community was revealed as a highly diverse reservoir of bacterial diversity dominated by actinobacteria. Hypolithic communities were less diverse and dominated by cyanobacteria. Major differences in putative functionality were that soil communities displayed greater diversity in stress tolerance and recalcitrant substrate utilization pathways, whilst hypolithic communities supported greater diversity of nutrient limitation adaptation pathways. A relatively high level of functional redundancy in both soil and hypoliths may indicate adaptation of these communities to fluctuating environmental conditions. PMID:27812351

  5. Taxonomic and functional diversity of soil and hypolithic microbial communities in Miers Valley, McMurdo Dry Valleys, Antarctica

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    Sean Wei

    2016-10-01

    Full Text Available The McMurdo Dry Valleys of Antarctica are an extreme polar desert. Mineral soils support subsurface microbial communities and translucent rocks support development of hypolithic communities on ventral surfaces in soil contact. Despite significant research attention relatively little is known about taxonomic and functional diversity or their inter-relationships. Here we report a combined diversity and functional interrogation for soil and hypoliths of the Miers Valley in the McMurdo Dry Valleys of Antarctica. The study employed 16S rRNA fingerprinting and high throughput sequencing combined with the GeoChip functional microarray. The soil community was revealed as a highly diverse reservoir of bacterial diversity dominated by actinobacteria. Hypolithic communities were less diverse and dominated by cyanobacteria. Major differences in putative functionality were that soil communities displayed greater diversity in stress tolerance and recalcitrant substrate utilization pathways, whilst hypolithic communities supported greater diversity of nutrient limitation adaptation pathways. A relatively high level of functional redundancy in both soil and hypoliths may indicate adaptation of these communities to fluctuating environmental conditions.

  6. 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.

  7. High-resolution elevation mapping of the McMurdo Dry Valleys, Antarctica, and surrounding regions

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    Fountain, Andrew G.; Fernandez-Diaz, Juan C.; Obryk, Maciej; Levy, Joseph; Gooseff, Michael; Van Horn, David J.; Morin, Paul; Shrestha, Ramesh

    2017-07-01

    We present detailed surface elevation measurements for the McMurdo Dry Valleys, Antarctica derived from aerial lidar surveys flown in the austral summer of 2014-2015 as part of an effort to understand geomorphic changes over the past decade. Lidar return density varied from 2 to > 10 returns m-2 with an average of about 5 returns m-2. Vertical and horizontal accuracies are estimated to be 7 and 3 cm, respectively. In addition to our intended targets, other ad hoc regions were also surveyed including the Pegasus flight facility and two regions on Ross Island, McMurdo Station, Scott Base (and surroundings), and the coastal margin between Cape Royds and Cape Evans. These data are included in this report and data release. The combined data are freely available at https://doi.org/10.5069/G9D50JX3" target="_blank">https://doi.org/10.5069/G9D50JX3.

  8. Halogens in the Dry Valleys Lakes, Antarctica: dynamic cycling between water, sediment, and cryogenic evaporites

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    Snyder, G. T.; Dowling, C. B.; Harbert, A.; Lu, H.; Lyons, W. B.; Welch, K. A.

    2006-12-01

    Many of the McMurdo Dry Valleys lakes of Antarctica exhibit saline to hypersaline bottom waters whose chemistry is distinct from that of sea water. The source and relative abundance of dissolved Cl, Br, and I in these unusual waters has been modified by several potential processes including: seawater incursions, water- rock interactions, microbial scavenging, glacial melting and precipitation, and atmospheric deposition. Since all of these processes are affected by both long-term and short-term climate change, lake waters and the salts that are deposited around them provide sensitive indicators of lake dessication and refilling in the past. We present elemental analyses, not only of the lake water, but also of bottom sediments and cryogenic evaporites recovered from the Dry Valleys. XRD analyses indicate that gypsum and antarcticite are precipitated around saline lakes presently situated more than 40 km from the ocean (Vanda, Don Juan, Joyce), while mirabilite is found near small pools in the Garwood Valley, only a few km from the ocean. Lake water enrichments in Ca and Cl, relative to Na suggest that either dissolution of gypsum and antarcticite has occurred in Don Juan Pond and Lake Vanda, or that these two small bodies of water previously lost sodium to mirabilite formation. Lakes Fryxell and Joyce, as well as waters in Garwood Valley show near-sea water ratios. Dissolved iodine, and to a lesser extent bromine, are commonly associated with diagenesis of marine organic matter in regions of high productivity, so it is surprising that the Dry Valleys lake waters are enriched in these two elements. These enrichments are also apparent in pore fluids of shallow sediments on the lake bottoms. In addition, the sediments themselves are highly enriched in iodine in the upper 5 cm (up to 77 ppm). This is likely due to remobilization of dissolved iodide, which is mobile in reduced form, but becomes fixed as adsorbed or organic iodine upon diffusing into shallow oxic

  9. Hydraulic conductivity of active layer soils in the McMurdo Dry Valleys, Antarctica: Geological legacy controls modern hillslope connectivity

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    Schmidt, Logan M.; Levy, Joseph S.

    2017-04-01

    Spatial variability in the hydraulic and physical properties of active layer soils influences shallow groundwater flow through cold-desert hydrological systems. This study measures the saturated hydraulic conductivity and grain-size distribution of 90 soil samples from the McMurdo Dry Valleys (MDV), Antarctica-primarily from Taylor Valley-to determine what processes affect the spatial distribution of saturated hydraulic conductivity in a simple, mineral-soil-dominated natural hillslope laboratory. We find that the saturated hydraulic conductivity and the grain-size distribution of soils are organized longitudinally within Taylor Valley. Soils sampled down-valley near the coast have a higher percentage of fine-sized sediments (fine sand, silt, clay) and lower saturated hydraulic conductivities than soils collected up-valley near Taylor Glacier (1.3 × 10- 2 vs. 1.2 × 10- 1 cm/s). Soils collected mid-valley have intermediate amounts of fines and saturated hydraulic conductivity values consistent with a hydrogeologic gradient spanning the valley from high inland to low near the coast. These results suggest the organization of modern soil properties within Taylor Valley is a relict signature from past glaciations that have deposited soils of decreasing age toward the mouth of the valley, modified by fluvial activity acting along temporal and microclimate gradients.

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

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    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.

  11. Climatic implications of reconstructed early - Mid Pliocene equilibrium-line altitudes in the McMurdo Dry Valleys, Antarctica

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    Krusic, A.G.; Prentice, M.L.; Licciardi, J.M.

    2009-01-01

    Early-mid Pliocene moraines in the McMurdo Dry Valleys, Antarctica, are more extensive than the present alpine glaciers in this region, indicating substantial climatic differences between the early-mid Pliocene and the present. To quantify this difference in the glacier-climate regime, we estimated the equilibrium-line altitude (ELA) change since the early-mid Pliocene by calculating the modern ELA and reconstructing the ELAs of four alpine glaciers in Wright and Taylor Valleys at their early-mid Pliocene maxima. The area-altitude balance ratio method was used on modern and reconstructed early-mid Pliocene hypsometry. In Wright and Victoria Valleys, mass-balance data identify present-day ELAs of 800-1600 m a.s.l. and an average balance ratio of 1.1. The estimated ELAs of the much larger early-mid Pliocene glaciers in Wright and Taylor Valleys range from 600 to 950 ?? 170 m a.s.l., and thus are 250-600 ??170 m lower than modern ELAs in these valleys. The depressed ELAs during the early-mid-Pliocene most likely indicate a wetter and therefore warmer climate in the Dry Valleys during this period than previous studies have recognized.

  12. Petrologic Consequences of the Magmatic Death of a Continental Arc: Vanda Dike Swarm, Dry Valleys, Antarctica

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    Harpp, K. S.; Christensen, B. C.; Geist, D. J.; Garcia, M. O.

    2005-12-01

    The Dry Valleys of southern Victoria Land, Antarctica, are notable for the presence of the Vanda dikes, prominent NE-trending swarms that crosscut a sequence of granitoid plutons. These older plutons are regional in extent and comprise 3 Cambro-Ordovician groups, including: a) calc-alkaline granitoids formed at an active plate margin during the Ross Orogeny (c. 505 Ma); b) adakitic granitoids, likely marking the conclusion of Ross Orogeny subduction-related activity (c. 490 Ma); and c) younger monzonitic plutons, probably generated in an intraplate extensional setting (Cox et al., 2000). The Vanda dikes crosscut the younger plutons, possibly between c. 490 and 477 Ma (Allibone et al., 1993; Encarnacion and Grunow, 1996). Dikes from the east wall of Bull Pass and the south wall of the Wright Valley range from 0.5-25 m wide with nearly vertical dips, are usually several km long, and, in the center of the swarms, occur with a frequency of ~18 dikes/km. Most have chilled margins and are surrounded by brittle fractures, indicative of shallow intrusion into cold country rock. Dike compositions are bimodal, most defining a trend at the boundary between the high-K calc-alkaline and shoshonite series in SiO2-K2O space; some Wright Valley dikes have slightly lower K2O and are calc-alkaline. Granite porphyry dikes are relatively homogeneous (69-73 wt.% SiO2), whereas the mafic dikes exhibit a wider range of compositions (49-57 wt.% SiO2). The felsic and mafic dikes have distinct trace element abundances but similar normalized distribution patterns, including fractionated heavy rare earth elements and negative Eu and high field-strength element anomalies. Average Sr/Y ratios of both the felsic and mafic dikes cluster around 20, well below a typical adakite signature. Major and trace element variations suggest that the felsic dikes may be differentiates of the mafic magmas. Field relations further indicate that the felsic lavas may represent, on average, a later phase of dike

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

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    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.

  14. Lichen myco- and photobiont diversity and their relationships at the edge of life (McMurdo Dry Valleys, Antarctica).

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    Pérez-Ortega, Sergio; Ortiz-Álvarez, Rüdiger; Allan Green, T G; de Los Ríos, Asunción

    2012-11-01

    Lichen-forming fungi are among the most diverse group of organisms in Antarctica. Being poikilohydric, lichens are able to cope with harsh environmental conditions that exclude other organisms like vascular plants. The McMurdo Dry Valleys (Victoria Land, Continental Antarctica) are a hyperarid cold desert where macroscopic life is reduced to a few lichens and bryophyte species. We investigated the diversity of lichen-forming fungi and their associated photobionts in three valleys (Garwood, Marshall, and Miers). Correct identification of lichen-forming fungi from extreme ecosystems is complicated by the presence of numerous sterile and extremely modified thalli. To overcome this problem, we used a combined approach for the identification of the species present in the area, the first involving identification by means of standard characters and the second, two DNA-based (ITS region) species delimitation methods (General Mixed Yule-Coalescent model and genetic distances). In addition, we also used ITS sequences for the identification of the photobionts associated with the mycobionts. We studied the relationships between both bionts and assessed the degree of selectivity and specificity found in those associations. We also looked for landscape level spatial patterns in these associations. The two DNA-based methods performed quite differently, but 27 species of lichen-forming fungi and five putative species of photobionts were found in the studied area. Although there was a general trend for low selectivity in the relationships, high specificity was found in some associations and differential selectivity was observed in some lichen-forming fungi. No spatial structure was detected in the distribution of photobionts in the studied area.

  15. A bacterial enrichment study and overview of the extractable lipids from paleosols in the Dry Valleys, Antarctica: implications for future Mars reconnaissance.

    Science.gov (United States)

    Hart, Kris M; Szpak, Michal T; Mahaney, William C; Dohm, James M; Jordan, Sean F; Frazer, Andrew R; Allen, Christopher C R; Kelleher, Brian P

    2011-05-01

    The Dry Valleys of Antarctica are one of the coldest and driest environments on Earth with paleosols in selected areas that date to the emplacement of tills by warm-based ice during the Early Miocene. Cited as an analogue to the martian surface, the ability of the Antarctic environment to support microbial life-forms is a matter of special interest, particularly with the upcoming NASA/ESA 2018 ExoMars mission. Lipid biomarkers were extracted and analyzed by gas chromatography--mass spectrometry to assess sources of organic carbon and evaluate the contribution of microbial species to the organic matter of the paleosols. Paleosol samples from the ice-free Dry Valleys were also subsampled and cultivated in a growth medium from which DNA was extracted with the explicit purpose of the positive identification of bacteria. Several species of bacteria were grown in solution and the genus identified. A similar match of the data to sequenced DNA showed that Alphaproteobacteria, Gammaproteobacteria, Bacteriodetes, and Actinobacteridae species were cultivated. The results confirm the presence of bacteria within some paleosols, but no assumptions have been made with regard to in situ activity at present. These results underscore the need not only to further investigate Dry Valley cryosols but also to develop reconnaissance strategies to determine whether such likely Earth-like environments on the Red Planet also contain life.

  16. Accuracy assessment of land surface temperature retrievals from Landsat 7 ETM + in the Dry Valleys of Antarctica using iButton temperature loggers and weather station data.

    Science.gov (United States)

    Brabyn, Lars; Zawar-Reza, Peyman; Stichbury, Glen; Cary, Craig; Storey, Bryan; Laughlin, Daniel C; Katurji, Marwan

    2014-04-01

    The McMurdo Dry Valleys of Antarctica are the largest snow/ice-free regions on this vast continent, comprising 1% of the land mass. Due to harsh environmental conditions, the valleys are bereft of any vegetation. Land surface temperature is a key determinate of microclimate and a driver for sensible and latent heat fluxes of the surface. The Dry Valleys have been the focus of ecological studies as they arguably provide the simplest trophic structure suitable for modelling. In this paper, we employ a validation method for land surface temperatures obtained from Landsat 7 ETM + imagery and compared with in situ land surface temperature data collected from four transects totalling 45 iButtons. A single meteorological station was used to obtain a better understanding of daily and seasonal cycles in land surface temperatures. Results show a good agreement between the iButton and the Landsat 7 ETM + product for clear sky cases. We conclude that Landsat 7 ETM + derived land surface temperatures can be used at broad spatial scales for ecological and meteorological research.

  17. The McMurdo Dry Valleys, Antarctica: Terrestrial and aquatic ecosystems responding to climatic events that enhance hydrologic transport across the landscape (John Dalton Medal Lecture)

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    McKnight, Diane

    2015-04-01

    While continuous monitoring of stream flow and stream temperature has been a widely used resource for some time, currently there is great potential to expand continuous monitoring to include important water quality parameters such as nutrients and dissolved organic material. In many systems distinguishing between watershed and stream ecosystem controls can be challenging, and the usefulness of such monitoring can be enhanced by application of quantitative models to interpret observed patterns. The glacial meltwater streams of the McMurdo Dry Valleys, Antarctica, are surrounded by large expanses of patterned ground devoid of plants. In contrast, many streams have thriving cyanobacterial mats that are freeze-dried through the winter and begin photosynthesis with the onset of flow. Thus, the daily signal in terms of biogeochemical processes controlling water quality is generated within the stream. As part of the McMurdo Dry Valleys Long Term Ecological Research project, we have conducted field experiments and developed coupled biogeochemical transport models for the role of hyporheic exchange in controlling weathering of major ions, microbial cycling of nitrogen species, and streams temperature regulation. We have also adapted modelling approaches from sediment transport to understand mobilization of stream biomass with increasing flows. These models are relevant to understanding the role of in-stream processes in diverse stream systems where watershed processes also contribute to observed patterns. In the future, monitored data may be directly incorporated into such process models to better understand rapid hydrologic change and their impact on water quality and aquatic ecosystems.

  18. Ground surface temperature and humidity, ground temperature cycles and the ice table depths in University Valley, McMurdo Dry Valleys of Antarctica

    Science.gov (United States)

    Fisher, David A.; Lacelle, Denis; Pollard, Wayne; Davila, Alfonso; McKay, Christopher P.

    2016-11-01

    In the upper McMurdo Dry Valleys, 90% of the measured ice table depths range from 0 to 80 cm; however, numerical models predict that the ice table is not in equilibrium with current climate conditions and should be deeper than measured. This study explored the effects of boundary conditions (air versus ground surface temperature and humidity), ground temperature cycles, and their diminishing amplitude with depth and advective flows (Darcy flow and wind pumping) on water vapor fluxes in soils and ice table depths using the REGO vapor diffusion model. We conducted a series of numerical experiments that illustrated different hypothetical scenarios and estimated the water vapor flux and ice table depth using the conditions in University Valley, a small high elevation valley. In situ measurements showed that while the mean annual ground surface temperature approximates that in the air, the mean annual ground surface relative humidity (>85%ice) was significantly higher than in the atmosphere ( 50%ice). When ground surface temperature and humidity were used as boundary conditions, along with damping diurnal and annual temperature cycles within the sandy soil, REGO predicted that measured ice table depths in the valley were in equilibrium with contemporary conditions. Based on model results, a dry soil column can become saturated with ice within centuries. Overall, the results from the new soil data and modeling have implications regarding the factors and boundary conditions that affect the stability of ground ice in cold and hyperarid regions where liquid water is rare.

  19. Soil temperatures and stability of ice-cemented ground in the McMurdo Dry Valleys, Antarctica.

    Science.gov (United States)

    McKay, C; Mellon, M T; Friedmann, E I

    1998-03-01

    Year-round temperature measurements at 1600 m elevation during 1994 in the Asgard Range Antarctica, indicate that the mean annual frost point of the ice-cemented ground, 25 cm below the surface, is -21.7 +/- 0.2 degrees C and the mean annual frost point of the atmosphere is -27.5 +/- 1.0 degrees C. The corresponding mean annual temperatures are -24.9 degrees C and -23.3 degrees C. These results imply that there is a net flux of water vapour from the ice to the atmosphere resulting in a recession of the ice-cemented ground by about 0.4-0.6 mm yr-1. The level of the ice-cemented permafrost is about 12 cm below the level of dry permafrost. The summer air temperatures would have to increase about 7 degrees C for thawing temperatures to just reach the top of the subsurface ice. Either subsurface ice at this location is evaporating over time or there are sporadic processes that recharge the ice and maintain equilibrium over long timescales.

  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. Stable isotope analyses of NO2-, NO3-, and N2O in the hypersaline ponds and soils of the McMurdo Dry Valleys, Antarctica

    Science.gov (United States)

    Peters, Brian; Casciotti, Karen L.; Samarkin, Vladimir A.; Madigan, Michael T.; Schutte, Charles A.; Joye, Samantha B.

    2014-06-01

    Nitrous oxide (N2O) is produced in significant quantities in the soils and lakes of the McMurdo Dry Valleys, Antarctica. Unraveling the mechanisms of N2O production in these soils and ponds is of great interest due to the extreme arid and cold conditions, which are hostile to life. Recent studies have shown production of N2O having unique stable isotopic signatures in certain Dry Valley soils through abiotic reduction of nitrate (NO3-) and nitrite (NO2-) on active surfaces of Fe(II)-containing minerals, a process known as ‘chemodenitrification’. In this study, δ15N and δ18O of N2O, NO2-, and NO3-, as well as the N2O site preference (SP), were measured at three sites to evaluate the role of chemodenitrification in N2O production. The δ15N and δ18O values in NO3- indicated an atmospheric source, while δ15N values in NO2- (-150‰) were indicative of abiotic reactions. Instead of finding unique SP values for N2O at Dry Valley sites, SP values mostly fell within the range associated with microbial N2O production mechansims. The δ15N and δ18O of N2O were also within a range of values expected for various biological N2O production mechanisms. However, efforts to detect biological activity in Don Juan Pond (DJP), a hypersaline pond in the Wright Valley, have been largely unsuccessful. We consider two possible scenarios for N2O production at DJP: (1) abiotic production in the pond, or (2) biological production in nearby freshwater and transport to the pond. Although little is known about the isotopic systematics of abiotic N2O production, these results indicate that if the observed N2O was produced by an abiotic mechanism, its isotopic signature is indistinguishable from that expected from a mixture of several microbial processes and thus, the formation pathway cannot be determined from isotopic composition alone.

  2. Microbial Community Responses to Increased Water and Organic Matter in the Arid Soils of the McMurdo Dry Valleys, Antarctica

    Directory of Open Access Journals (Sweden)

    Heather N Buelow

    2016-07-01

    Full Text Available The soils of the McMurdo Dry Valleys, Antarctica are an extreme polar desert, inhabited exclusively by microscopic taxa. This region is on the threshold of anticipated climate change, with glacial melt, permafrost thaw, and the melting of massive buried ice increasing liquid water availability and mobilizing soil nutrients. Experimental water and organic matter (OM amendments were applied to investigate how these climate change effects may impact the soil communities. To identify active taxa and their functions, total community RNA transcripts were sequenced and annotated, and amended soils were compared with unamended control soils using differential abundance and expression analyses. Overall, taxonomic diversity declined with amendments of water and organic matter. The domain Bacteria increased with both amendments while Eukaryota declined from 38% of all taxa in control soils to 8% and 11% in water and OM amended soils, respectively. Among bacterial phyla, Actinobacteria (59% dominated water-amended soils and Firmicutes (45% dominated OM amended soils. Three bacterial phyla (Actinobacteria, Proteobacteria, and Firmicutes were primarily responsible for the observed positive functional responses, while eukaryotic taxa experienced the majority (27 of 34 of significant transcript losses. These results indicated that as climate changes in this region, a replacement of endemic taxa adapted to dry, oligotrophic conditions by generalist, copiotrophic taxa is likely.

  3. Temporal variations in physical and chemical features of cryoconite holes on Canada Glacier, McMurdo Dry Valleys, Antarctica

    Science.gov (United States)

    Fountain, Andrew G.; Nylen, Thomas H.; Tranter, Martyn; Bagshaw, Elizabeth

    2008-03-01

    Cryoconite holes in the McMurdo Dry Valleys are ice-lidded, thus isolating the pools of water from the atmosphere and from potential surface melt. Hourly measurements of ice and water temperature and water electrical conductivity (EC) were recorded to broadly characterize the physical and chemical changes on daily to seasonal timescales. Overall, subsurface ice/water temperatures were typically several degrees warmer than air temperatures, underscoring the importance of subsurface solar heating. At no time was surface melt observed and the holes melted from within. Detailed differences in the timing and magnitude of both temperature and EC variations during melt-out and freezeup existed between holes despite short separation distances (<1 m). We attribute these differences to small-scale changes in the optical characteristics of the ice and perhaps different efficiencies in hydrologic connections between holes. The holes melt-deepened quickly in the first half of the summer before slowing to a rate equal to the rate of surface ablation that kept hole depth constant for the remainder of the season. The relatively constant EC of the hole waters during midsummer indicates that these holes were connected to a subsurface water system that flushed the holes with fresher meltwater. The early and late season ECs are dominated by freeze-thaw effects that concentrate/dilute the solutes. We speculate that high solute concentrations imply high nutrient concentrations in early summer that may help alleviate potential stresses caused by the production of new biomass after the winter freeze.

  4. Challenges to Airborne and Orbital Radar Sounding in the Presence of Surface Clutter: Lessons Learned (so far) from the Dry Valleys of Antarctica

    Science.gov (United States)

    Holt, J. W.; Peters, M. E.; Kempf, S. D.; Morse, D. L.; Blankenship, D. D.

    2005-12-01

    The search for life and in-situ resources for exploration on Mars targets both liquid and solid water, whether distributed or in reservoirs. Massive surface ice may cover potential habitats or other features of great interest. Ice-rich layering in the high latitudes holds clues to the climatic history of the planet. Multiple geophysical methods will clearly be necessary to fully characterize these various states of water (and other forms of ice), but radar sounding will be a critical component of the effort. Orbital radar sounders are already being employed and plans for surface-based and suborbital, above-surface radar sounders are being discussed. The difficulties in interpreting data from each type of platform are quite different. Given the lack of existing orbital radar sounding data from any planetary body, the analysis of airborne radar sounding data is quite useful for assessing the advantages and disadvantages of above-surface radar sounding on Mars. In addition to over 300,000 line-km of data collected over the Antarctic ice sheet by airborne radar sounding, we have recently analyzed data from the Dry Valleys of Antarctica where conditions and features emulate Mars in several respects. These airborne radar sounding data were collected over an ice-free area of Taylor Valley, ice-covered lakes, Taylor Glacier, and Beacon Valley. The pulsed radar (52.5 - 67.5 MHz chirp) was coherently recorded. Pulse compression and unfocused SAR processing were applied. One of the most challenging aspects of above-surface radar sounding is the determination of echo sources. This can, of course, be problematic for surface-based radar sounders given possible subsurface scattering geometries, but it is most severe for above-surface sounders because echoes from cross-track surface topography (surface clutter) can have similar time delays to those from the subsurface. We have developed two techniques to accomplish the identification of this surface clutter in single-pass airborne

  5. Dilution-to-extinction culturing of psychrotolerant planktonic bacteria from permanently ice-covered lakes in the McMurdo Dry Valleys, Antarctica.

    Science.gov (United States)

    Stingl, U; Cho, J-C; Foo, W; Vergin, K L; Lanoil, B; Giovannoni, S J

    2008-04-01

    Lakes in the McMurdo Dry Valleys of Antarctica are characterized by a permanent ice cover and little or no anthropogenic influence. Although bacterial cultures have been obtained from these habitats, recent culture-independent studies indicate that the most abundant microbes in these systems are not yet cultivated. By using dilution-to-extinction cultivation methods with sterilized and nutrient-amended lake water as media, we isolated 148 chemotrophic psychrotolerant bacterial cultures from fresh surface water of Lake Fryxell and the east lobe of Lake Bonney and the hypersaline, suboxic bottom water from the west lobes of Lake Bonney. Screening of the 16S ribosomal ribonucleic acid (rRNA) genes of the cultures by restriction fragment length polymorphism (RFLP) yielded 57 putatively pure psychrotolerant, slow growing cultures grouped into 18 clusters. The sequencing of 16S rRNA genes of randomly selected representatives of each RFLP cluster revealed that the corresponding isolates belong to the Alphaproteobacteria (six RFLP patterns), Betaproteobacteria (six RFLP patterns), Bacteroidetes (four RFLP patterns), and Actinobacteria (two RFLP patterns). Phylogenetic analysis of the sequences showed that the vast majority of the isolates were not closely related to previously described species. Thirteen of 18 RFLP patterns shared a 16S ribosomal deoxyribonucleic acid sequence similarity of 97% or less with the closest described species, and four isolates had a sequence similarity of 93% or less with the nearest described species. Phylogenetic analysis showed that these sequences were representatives of deeply branching organisms in the respective phylum. A comparison of the isolates with 16S rRNA clone libraries prepared from the same environments showed substantial overlap, indicating that dilution-to-extinction culturing in natural lake water media can help isolate some of the most abundant organisms in these perennially ice-covered lakes.

  6. Stromatolites Record Changing Primary Productivity in Perennially Ice-Covered Lake Joyce, McMurdo Dry Valleys, Antarctica

    Science.gov (United States)

    Mackey, T. J.; Sumner, D. Y.; Hawes, I.; Jungblut, A. D.; Leidman, S. Z.; Andersen, D. T.

    2016-12-01

    Calcite-rich dm-scale columnar stromatolites grew in perennially ice-covered Lake Joyce, Antarctica, and their calcite contains carbon isotopic records of microbial activity during recent lake level rise. Stromatolite growth initiated in water depths < 10 m based on the presence of bubble molds in calcite, and growth ended prior to 2009 when stromatolites were at 20-22 m water depth and received insufficient irradiance for net photosynthetic growth. Some calcite layers in the stromatolites contain cyanobacterial microfossils as well as sediment laminae, which indicate that this calcite precipitated at the stromatolite surface in association with photosynthesizing communities. The innermost stromatolite layers have variable δ13C values ranging from 3.9 to 9.6‰ in coeval calcite. Regions such as topographic highs and parts of stromatolites growing into open water have both thicker calcite layers and δ13C values that are 0.3 to 1.0‰ higher than other areas. Outer stromatolite layers have a smaller range of δ13Ccalcite values spanning 1.3‰. Variations in carbon isotopes can be attributed to photosynthetic effects. Photosynthetic shallow modern mats in Lake Joyce have pH up to 0.4 units higher than the water column, and pH increases and decreases with irradiance through diurnal cycles. Irradiance also varies laterally; light transmission through the Lake Joyce ice cover varied over 500% laterally in 2014. If the modern mats reflect conditions present during early stromatolite growth, high photosynthetic rates likely enhanced calcite precipitation and produced a photosynthetic δ13C signature in stromatolitic calcite. Variability in innermost stromatolite δ13C values is consistent with different rates of photosynthesis due to laterally variable light transmission through the ice. With lake level rise, incident irradiance decreased and became more uniform, leading to more consistent δ13Ccalcite values. Lake Joyce stromatolites thus record the effects of

  7. Seasonal controls on snow distribution and aerial ablation at the snow-patch and landscape scales, McMurdo Dry Valleys, Antarctica

    OpenAIRE

    Eveland, J. W.; M. N. Gooseff; Lampkin, D. J.; Barrett, J E; Takacs-Vesbach, C. D.

    2013-01-01

    Accumulated snow in the McMurdo Dry Valleys, while limited, has great ecological significance to subnivian soil environments. Though sublimation dominates the ablation process in this region, measurable increases in soil moisture and insulation from temperature extremes provide more favorable conditions with respect to subnivian soil communities. While precipitation is not substantial, significant amounts of snow can accumulate, via wind transport, in topographic lees along the valley bottoms...

  8. Two Decades of Variability in Nutrient Budgets for Ice-Covered, Closed Basin Lakes in the McMurdo Dry Valleys, Antarctica

    Science.gov (United States)

    Truhlar, A. M.; Gooseff, M. N.; McKnight, D. M.; Priscu, J. C.; Doran, P. T.

    2013-12-01

    The McMurdo Dry Valleys (MCM) of Antarctica represent one of the world's driest deserts. A collection of permanently ice-covered lakes in the MCM provide an important refuge for microorganisms. Thus, it is of interest to understand the nutrient dynamics of these lakes and how these dynamics have changed over time. One to two decade-long records of physical, chemical, and biological characteristics in the East Lobe of Lake Bonney (ELB), Lake Fryxell (FRX), and Lake Hoare (HOR) allowed for development of annual nutrient budgets and analysis of possible causes of variability. Annual nutrient budgets were built by accounting for total seasonal streamflow and average seasonal nutrient concentration in streamflow, as well as nutrient diffusion across the chemocline, which roughly coincides with the bottom of the photic zone. Unaccounted-for changes in nutrient content were assumed to be caused by processes internal to the lake. Changes to the proportion of lake volume in the photic zone, seasonal streamflow, and biological activity, represented by chlorophyll-a (CHL) concentration, were considered as potential explanations. For all three lakes, nutrient diffusion either into or out of the photic zone was minimal compared to nutrient inputs from streamflow. The sole exception to this was NH4 inputs to FRX; for eight of the nine years considered, diffusive inputs of NH4 to the photic zone were greater than streamflow inputs. In most cases, internal processes appeared to dominate over streamflow inputs; this is likely because seasonal streamflow represented less than 8% of the photic zone volume in all three lakes. Three exceptions to this trend were the phosphorus budget in ELB, and the NH4 and NO3 budgets in HOR; in these cases, streamflow inputs represented a notable portion of the annual nutrient budgets. The MCM lakes decreased in volume from the early 1990s to the early 2000s; they have since been increasing in volume. The volume of the photic zone was positively

  9. 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

  10. Biogeochemical stoichiometry of Antarctic Dry Valley ecosystems

    Science.gov (United States)

    Barrett, J. E.; Virginia, R. A.; Lyons, W. B.; McKnight, D. M.; Priscu, J. C.; Doran, P. T.; Fountain, A. G.; Wall, D. H.; Moorhead, D. L.

    2007-03-01

    Among aquatic and terrestrial landscapes of the McMurdo Dry Valleys, Antarctica, ecosystem stoichiometry ranges from values near the Redfield ratios for C:N:P to nutrient concentrations in proportions far above or below ratios necessary to support balanced microbial growth. This polar desert provides an opportunity to evaluate stoichiometric approaches to understand nutrient cycling in an ecosystem where biological diversity and activity are low, and controls over the movement and mass balances of nutrients operate over 10-106 years. The simple organisms (microbial and metazoan) comprising dry valley foodwebs adhere to strict biochemical requirements in the composition of their biomass, and when activated by availability of liquid water, they influence the chemical composition of their environment according to these ratios. Nitrogen and phosphorus varied significantly in terrestrial and aquatic ecosystems occurring on landscape surfaces across a wide range of exposure ages, indicating strong influences of landscape development and geochemistry on nutrient availability. Biota control the elemental ratio of stream waters, while geochemical stoichiometry (e.g., weathering, atmospheric deposition) evidently limits the distribution of soil invertebrates. We present a conceptual model describing transformations across dry valley landscapes facilitated by exchanges of liquid water and biotic processing of dissolved nutrients. We conclude that contemporary ecosystem stoichiometry of Antarctic Dry Valley soils, glaciers, streams, and lakes results from a combination of extant biological processes superimposed on a legacy of landscape processes and previous climates.

  11. 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.

  12. 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

    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......-age micro-hole age estimates for the deltas range from ∼50 to 100 a near the present lake level up to 13.4 ± 1.3 ka at 240 m. These are systematically younger than the comparable, reservoir-uncorrected, 14C ages that range from 7 ka (cal yr BP) to 13 ka (cal yr BP) near lake level up to 20 ka (cal yr BP...

  13. Seasonal controls on snow distribution and aerial ablation at the snow-patch and landscape scales, McMurdo Dry Valleys, Antarctica

    Directory of Open Access Journals (Sweden)

    J. W. Eveland

    2013-06-01

    Full Text Available Accumulated snow in the McMurdo Dry Valleys, while limited, has great ecological significance to subnivian soil environments. Though sublimation dominates the ablation process in this region, measurable increases in soil moisture and insulation from temperature extremes provide more favorable conditions with respect to subnivian soil communities. While precipitation is not substantial, significant amounts of snow can accumulate, via wind transport, in topographic lees along the valley bottoms, forming thousands of discontinuous snow patches. These patches have the potential to act as significant sources of local meltwater, controlling biogeochemical cycling and the landscape distribution of microbial communities. Therefore, determining the spatial and temporal dynamics of snow at multiple scales is imperative to understanding the broader ecological role of snow in this region. High-resolution satellite imagery acquired during the 2009–2010 and 2010–2011 austral summers was used to quantify the distribution of snow across Taylor and Wright valleys. Extracted snow-covered area from the imagery was used as the basis for assessing inter-annual variability and seasonal controls on accumulation and ablation of snow at multiple scales. In addition to landscape analyses, fifteen 1 km2 plots (3 in each of 5 study regions were selected to assess the prevalence of snow cover at finer spatial scales, referred to herein as the snow-patch scale. Results confirm that snow patches tend to form in the same locations each year with some minor deviations observed. At the snow-patch scale, neighboring patches often exhibit considerable differences in aerial ablation rates, and particular snow patches do not reflect trends for snow-covered area observed at the landscape scale. These differences are presumably related to microtopographic influences acting on individual snow patches, such as wind sheltering and differences in snow depth due to the underlying

  14. Seasonal controls on snow distribution and aerial ablation at the snow-patch and landscape scales, McMurdo Dry Valleys, Antarctica

    Directory of Open Access Journals (Sweden)

    J. W. Eveland

    2012-09-01

    Full Text Available Accumulated snow in the McMurdo Dry Valleys, while limited, has great ecological significance to subnivian soil environments. Though sublimation dominates the ablation process in this region, measurable increases in soil moisture and insulation from temperature extremes provide more favorable conditions with respect to subnivian soil communities. While precipitation is not substantial, significant amounts of snow can accumulate, via aeolian redistribution, in topographic lees along the valley bottoms, forming thousands of discontinuous snow patches. These patches have the potential to act as significant sources of local melt water, controlling biogeochemical cycling and the landscape distribution of microbial communities. Therefore, determining the spatial and temporal dynamics of snow at multiple scales is imperative to understanding the broader ecological role of snow in this region.

    High-resolution satellite imagery acquired during the 2009–2010 and 2010–2011 austral summers was used to quantify the distribution of snow across Taylor and Wright Valleys. Extracted snow-covered area from the imagery was used as the basis for assessing seasonal variability and seasonal controls on accumulation and ablation of snow at multiple scales. In addition, fifteen 1 km2 plots (3 in each of 5 study regions were selected to assess the prevalence of snow cover at finer spatial scales. Results confirm that snow patches tend to form in the same locations each year with some minor deviations observed. At the snow-patch scale, neighboring patches often exhibit considerable differences in aerial ablation rates, and particular snow patches do not reflect trends for snow-covered area observed at the landscape scale. These differences are presumably related to microtopographic influences over snow depth and exposure. This highlights the importance of both the landscape and snow-patch scales in assessing the effects of snow cover on

  15. Draft genome of Kocuria polaris CMS 76or(T) isolated from cyanobacterial mats, McMurdo Dry Valley, Antarctica: an insight into CspA family of proteins from Kocuria polaris CMS 76or(T).

    Science.gov (United States)

    Gundlapally, Sathyanarayana Reddy; Ara, Srinivas; Sisinthy, Shivaji

    2015-10-01

    Kocuria polaris strain CMS 76or(T) is a gram-positive, orange-pigmented bacterium isolated from a cyanobacterial mat sample from a pond located in McMurdo Dry Valley, Antarctica. It is psychrotolerant, orange pigmented, hydrolyses starch and Tween 80 and reduces nitrate. We report the 3.78-Mb genome of K. polaris strain CMS 76or(T), containing 3416 coding sequences, including one each for 5S rRNA, 23S rRNA, 16S rRNA and 47 tRNA genes, and the G+C content of DNA is 72.8%. An investigation of Csp family of proteins from K. polaris strain CMS 76or(T) indicated that it contains three different proteins of CspA (peg.319, peg.2255 and 2832) and the length varied from 67 to 69 amino acids. The three different proteins contain all the signature amino acids and two RNA binding regions that are characteristic of CspA proteins. Further, the CspA from K. polaris strain CMS 76or(T) was different from CspA of four other species of the genus Kocuria, Cryobacterium roopkundense and E. coli indirectly suggesting the role of CspA of K. polaris strain CMS 76or(T) in psychrotolerant growth of the bacterium.

  16. Functional ecology of an Antarctic Dry Valley

    Science.gov (United States)

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

    2013-01-01

    The McMurdo Dry Valleys are the largest ice-free region in Antarctica and are critically at risk from climate change. The terrestrial landscape is dominated by oligotrophic mineral soils and extensive exposed rocky surfaces where biota are largely restricted to microbial communities, although their ability to perform the majority of geobiological processes has remained largely uncharacterized. Here, we identified functional traits that drive microbial survival and community assembly, using a metagenomic approach with GeoChip-based functional gene arrays to establish metabolic capabilities in communities inhabiting soil and rock surface niches in McKelvey Valley. Major pathways in primary metabolism were identified, indicating significant plasticity in autotrophic, heterotrophic, and diazotrophic strategies supporting microbial communities. This represents a major advance beyond biodiversity surveys in that we have now identified how putative functional ecology drives microbial community assembly. Significant differences were apparent between open soil, hypolithic, chasmoendolithic, and cryptoendolithic communities. A suite of previously unappreciated Antarctic microbial stress response pathways, thermal, osmotic, and nutrient limitation responses were identified and related to environmental stressors, offering tangible clues to the mechanisms behind the enduring success of microorganisms in this seemingly inhospitable terrain. Rocky substrates exposed to larger fluctuations in environmental stress supported greater functional diversity in stress-response pathways than soils. Soils comprised a unique reservoir of genes involved in transformation of organic hydrocarbons and lignin-like degradative pathways. This has major implications for the evolutionary origin of the organisms, turnover of recalcitrant substrates in Antarctic soils, and predicting future responses to anthropogenic pollution. PMID:23671121

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

    Science.gov (United States)

    Bockheim, James 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.

  18. Endolithic blue-green algae in the dry valleys: primary producers in the antarctic desert ecosystem.

    Science.gov (United States)

    Friedmann, E I; Ocampo, R

    1976-09-24

    Endolithic unicellular blue-green algae occur under the surface of orthoquartzite rocks in the dry valleys of southern Victoria Land, Antarctica. This report of primary producers in the Antarctic desert ecosystem suggests that, in future efforts to detect life in extraterrestrial (for example, martian) environments, scientists should consider the possible existence of endolithic life forms.

  19. Don Juan Basin, Wright Valley, Antarctica: Model for Surface Processes on Mars

    Science.gov (United States)

    Englert, P.; Bishop, J. L.; Gibson, E. K.; Patel, S.; Koeberl, C.

    2014-09-01

    Mineral, chemical, and soluble salt composition of drill core samples from Don Juan Basin, Wright Valley, Antarctica, indicate that the formation of the most saline terrestrial pond may include groundwater discharge and near surface flow processes.

  20. 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.

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

    Science.gov (United States)

    Dreesens, Lisa L.; Lee, Charles K.; Cary, S. Craig

    2014-01-01

    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. PMID:25079129

  2. 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.

  3. Viable microbes in ice: Application of molecular assays to McMurdo Dry Valley lake ice communities

    NARCIS (Netherlands)

    Dieser, M.; Nocker, A.; Priscu, J.C.; Foreman, C.M.

    2010-01-01

    The permanent ice covers of the McMurdo Dry Valley lakes, Antarctica, are colonized by a diverse microbial assemblage. We collected ice cores from Lakes Fryxell, Hoare and Bonney. Propidium monoazide (PMA) was used in combination with quantitative PCR (qPCR) and denaturing gradient gel electrophores

  4. Viable microbes in ice: Application of molecular assays to McMurdo Dry Valley lake ice communities

    NARCIS (Netherlands)

    Dieser, M.; Nocker, A.; Priscu, J.C.; Foreman, C.M.

    2010-01-01

    The permanent ice covers of the McMurdo Dry Valley lakes, Antarctica, are colonized by a diverse microbial assemblage. We collected ice cores from Lakes Fryxell, Hoare and Bonney. Propidium monoazide (PMA) was used in combination with quantitative PCR (qPCR) and denaturing gradient gel electrophores

  5. Viscous flow lobes in central Taylor Valley, Antarctica: Origin as remnant buried glacial ice

    Science.gov (United States)

    Swanger, Kate M.; Marchant, David R.; Kowalewski, Douglas E.; Head, James W., III

    2010-08-01

    Viscous flow lobes are common throughout the McMurdo Dry Valleys (MDV) of Antarctica. These features have been described as rock glaciers, gelifluction lobes, solifluction lobes, talus mobilized by pore ice and/or segregation ice, and debris-covered glaciers. We investigate the origin, modification, and flow of a 2-km-long lobe (East Stocking Lobe or ESL) along the north wall of central Taylor Valley using field mapping techniques, shallow seismic surveys, time-dependent displacement surveys, and isotopic analyses of buried-ice samples. On the basis of these integrated analyses, we show that the ESL is cored with remnant glacier ice, most probably derived from an advance of nearby Stocking Glacier ˜ 130 kyr BP. Seismic data, coupled with results from ice-flow modeling assuming plastic flow of clean ice, suggest that the buried core of glacier ice is ˜ 14- to 30-m thick. Near its terminus, the ESL flows at a rate of ˜ 2.4 to 6.7 mm a - 1 . The loose drift that caps the buried ice (typically analyses of samples from the upper 30 cm of the ice lie on a slope of ˜ 5.8 (when plotted on a δD vs. δ18O graph), well below the local meteoric water line of 7.75, suggesting modification by freeze/thaw processes and evaporation/sublimation. Measured air and soil temperatures show that intermittent melting is most likely possible during summer months where buried ice is ≤ 35 cm below the ground surface. Morphological comparisons with ice-cored deposits in upland regions of the Dry Valleys, e.g., Mullins and Beacon Valleys (30 km inland and ˜ 500 m higher in elevation), and near the coast (40 km distant and ˜ 500 m lower) reveal marked contrasts in the style of near-surface ice degradation and cryoturbation. From these morphological comparisons, we infer that buried-ice deposits in the stable upland zone have not experienced the relatively warm climate conditions now found at the ESL and at lower elevations in the Dry Valleys region (e.g. sustained summertime

  6. Characterization of a halotolerant-psychroloterant bacterium from dry valley Antarctic soil.

    Science.gov (United States)

    Miller, K J; Leschine, S B; Huguenin, R L

    1983-01-01

    The saline soils of the ice free dry valleys of Victoria Land, Antarctica may provide the closest analog on Earth to Martian conditions. We have initiated a study aimed at examining microbial adaptations to the harsh environment of these dry valley soils. In this report we describe the characterization of one bacterium, strain A4a, isolated from Taylor Valley soil. Strain A4a was an obligately aerobic, orange-pigmented, Gram-positive coccus that grew over wide ranges of both temperature (0 degrees C-40 degrees C) and sodium chloride concentration (0-2.0M). The optimal temperature for growth at all NaCl concentrations was 25 degrees C. Phospholipid composition and guanine plus cytosine content of the DNA of the isolate indicate a close relation to the genus Planococcus.

  7. Chemodenitrification in the cryoecosystem of Lake Vida, Victoria Valley, Antarctica.

    Science.gov (United States)

    Ostrom, N E; Gandhi, H; Trubl, G; Murray, A E

    2016-11-01

    Lake Vida, in the Victoria Valley of East Antarctica, is frozen, yet harbors liquid brine (~20% salt, >6 times seawater) intercalated in the ice below 16 m. The brine has been isolated from the surface for several thousand years. The brine conditions (permanently dark, -13.4 °C, lack of O2 , and pH of 6.2) and geochemistry are highly unusual. For example, nitrous oxide (N2 O) is present at a concentration among the highest reported for an aquatic environment. Only a minor (17) O anomaly was observed in N2 O, indicating that this gas was predominantly formed in the lake. In contrast, the (17) O anomaly in nitrate (NO3-) in Lake Vida brine indicates that approximately half or more of the NO3- present is derived from atmospheric deposition. Lake Vida brine was incubated in the presence of (15) N-enriched substrates for 40 days. We did not detect microbial nitrification, dissimilatory reduction of NO3- to ammonium (NH4+), anaerobic ammonium oxidation, or denitrification of N2 O under the conditions tested. In the presence of (15) N-enriched nitrite (NO2-), both N2 and N2 O exhibited substantial (15) N enrichments; however, isotopic enrichment declined with time, which is unexpected. Additions of (15) N-NO2- alone and in the presence of HgCl2 and ZnCl2 to aged brine at -13 °C resulted in linear increases in the δ(15) N of N2 O with time. As HgCl2 and ZnCl2 are effective biocides, we interpret N2 O production in the aged brine to be the result of chemodenitrification. With this understanding, we interpret our results from the field incubations as the result of chemodenitrification stimulated by the addition of (15) N-enriched NO2- and ZnCl2 and determined rates of N2 O and N2 production of 4.11-41.18 and 0.55-1.75 nmol L(-1)  day(-1) , respectively. If these rates are representative of natural production, the current concentration of N2 O in Lake Vida could have been reached between 6 and 465 years. Thus, chemodenitrification alone is sufficient to explain the

  8. 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.

  9. Soluble Salt Accumulations in Taylor Valley, Antarctica: Implications for Paleolakes and Ross Sea Ice Sheet Dynamics

    Science.gov (United States)

    Toner, J. D.; Sletten, R. S.; Prentice, M. L.

    2012-12-01

    Soluble salt accumulations in Taylor Valley, Antarctica, provide a history of paleolakes and the advance of the Ross Sea Ice Sheet (RSIS). We measured soluble salts in 89 soils throughout Taylor Valley in soil-water extractions. In western Taylor Valley, soluble salt accumulations are relatively high and are comprised primarily of Na, Ca, Cl, and SO4. In eastern Taylor Valley, soluble salt accumulations are much lower and are comprised primarily of Na and HCO3. Salt compositions measured in soil-water extractions are highly influenced by the dissolution of sparingly soluble salts (e.g. calcite and gypsum) and cation exchange reactions. Furthermore, during soil-water extractions, Ca from calcite or gypsum dissolution exchanges with exchangeable Na, K, and Mg. These processes can strongly influence both the total salt content measured in soils and ionic ratios. Thus, it is important to consider the effects of these reactions when interpreting soluble salt accumulations measured in soil-water extractions. Calcite dissolution and cation exchange reactions also appear to have a widespread natural occurrence, resulting in the Na-HCO3 compositions of soils, streams, and lakes in eastern Taylor Valley. The soluble salt data supports the hypotheses that a lobe of the RSIS expanded into eastern Taylor Valley and dammed proglacial paleolakes. However, in contrast to previous studies, our findings indicate that the RSIS advanced deeper into Taylor Valley and that paleolakes were less extensive. By comparing soluble salt distributions across Taylor Valley, we conclude that a lobe of the RSIS filled all of eastern Taylor Valley and dammed paleolakes in western Taylor Valley up to 300 m elevation. Following ice retreat, smaller paleolakes formed in both western and eastern Taylor Valley up to about 120 m, with a prominent still stands at 80 m that was controlled by the elevation of a major valley threshold.

  10. Antarctica

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    ANYONEwhohasbeentoAntarctica,asIhave,willviewplanetearthfromanewangle.Whenyoutravel10,000kilometers,walkoutontothevastpolarcontinentandbreatheinitscrystallineair,aheightenedsenseoflivingonaglobe,ofbelongingtoalargeruniverse,willtakerootinyourmind.AnU...

  11. Glacial geomorphology of the Victoria Valley System, Ross Sea Region, Antarctica

    Science.gov (United States)

    Bockheim, James G.; McLeod, Malcolm

    2013-07-01

    During the 2011-2012 austral summer, we had the opportunity to verify a surficial geology map prepared nearly 50 years ago for the Victoria Valley system (VVS), the largest of the McMurdo Dry Valleys. We used high-resolution landsat images and a digital elevation model to identify landforms and prepare detailed maps of each of the five valleys in the VVS, including lateral and end moraines, rock glaciers, gelifluction sheets, gravel ripples, and hummocky and ice-cored drifts. Our mapping suggests that the Bull drift is less extensive than previously thought, attains a maximum elevation of ~ 750 m in Balham and Barwick Valleys and the upper Bull Pass region, and does not occur in McKelvey Valley. We found Insel drift to 850 m elevation in eastern McKelvey Valley and upper Bull Pass and were able to trace Insel drift down Bull Pass where it becomes Peleus drift in Wright Valley. The Victoria Lower Glacier likely responded to grounding of ice in the Ross Embayment and was out-of-phase with alpine glaciers elsewhere in the VVS. We amplified and quantified Calkin's relative chronology and provide here our multiple-parameter relative chronology for the McMurdo Dry Valleys that is based on surface-boulder weathering, soil weathering, salt stage, degree of development of the desert pavement, and form of patterned ground. Except for Victoria Lower Valley, we correlate Packard drift with Taylor II drift (ca., 120 ka), Vida drift with Taylor III drift (ca., 300 ka), Bull drift with Taylor IVb drift (2.7-3.5 Ma, and Insel drift with Peleus drift (> 3.7 Ma, < 5.4 Ma). The lack of a strong correlation between soil salt stage and depth of visible salts with elevation leads us to question whether a high-level lake (ca., 200 m deep) existed in the VVS during the early Holocene.

  12. The helium isotopic chemistry of Lake Bonney, Taylor Valley, Antarctica: Timing of late holocene climate change in Antarctica

    Science.gov (United States)

    Poreda, R.J.; Hunt, A.G.; Berry, Lyons W.; Welch, K.A.

    2004-01-01

    To better understand the long-term climate history of Antarctica, we studied Lake Bonney in Taylor Valley, Southern Victoria Land (78?? S). Helium isotope ratios and He, Ne, Ar and N2 concentration data, obtained from hydrocasts in the East (ELB) and West (WLB) Lobesof Lake Bonney, provided important constraints on the lake's Holocene evolution. Based on very low concentrations of Ar and N2 in the ELB bottom waters, ELB was free of ice until 200 ?? 50 years ago. After which, low salinity water flowing over the sill from WLB to ELB, covered ELB and formed a perennial ice cover, inhibiting the exchange of gases with the atmosphere. In contrast to the ELB, the WLB retained an ice cover through the Holocene. The brine in the WLB bottom waters has meteoric N2 and Ar gas concentrations indicating that it has not been significantly modified by atmospheric exchange or ice formation. The helium concentrations in the deep water of WLB are the highest measured in non-thermal surface water. By fitting a diffusional loss to the 3He/4He, helium, and Cl profiles, we calculate a time of ???3000 years for the initiation of flow over the sill separating the East and West Lobes. To supply this flux of helium to the lake, a helium-rich sediment beneath the lake must be providing the helium by diffusion. If at any time during the last million years the ice cover left WLB, there would be insufficient helium available to provide the current flux to WLB. The variations in water levels in Lake Bonney can be related to climatic events that have been documented within the Southern Victoria Land region and indicate that the lakes respond significantly to regional and, perhaps, global climate forcing. ?? 2004 Kluwer Academic Publishers.

  13. 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.

  14. Glaciers Change in the McMurdo Dry Valleys, Beginning of the End?

    Science.gov (United States)

    Fountain, A. G.; Basagic, H. J.; Nylen, T. H.; Hoffman, M.

    2011-12-01

    The McMurdo Dry Valleys are the largest expanse of ice-free landscape in Antarctica and we report here on our efforts to integrate remote sensed measurements with ground-based measurements to synthesize glacier change in the Valleys. We have been monitoring glacier mass balance in the Valleys since 1993 and tracking changes in glacier area from historic hand-held photographs dating to Scott's first expedition in 1903, and again starting in the 1970s with the New Zealand program. From the 1950s onward we have included aerial photographs in our glacier monitoring and since the 1970s satellite imagery has been included. Within the uncertainty of the measurements, we observed little to no change in glacier area over the past 100+ years. Certainly some portions of the glacier perimeter have advanced or retreated slightly, but overall the glacier area had not changed. We note that handheld photographs of a point change on the perimeter, the most accurate because of ice flow parallel to the plane of the image, to be deceptive compared to compensating changes elsewhere around the perimeter. Annual mass balance measurements over the first decade of measurements showed the glaciers to be in balance within our measurement uncertainty with no significant trend. Since the 2002-03 season, a significant trend has emerged showing a negative mass loss. Summer rather than winter losses drive this trend. The summer losses are not due to summer air temperatures, which continue to cool or have remained cool. Instead we attribute the losses to the trend of increasing solar radiation and increased eolian sediment deposition on the glaciers, which reduces the albedo. At a few unmeasured glaciers, photographic evidence suggests sediment to cause a dramatic mass loss. The lack of observed change in glacier area from satellite imagery over the past decade despite measured mass losses is consistent with the slow time-scale response of these polar glaciers.

  15. Modeling the Thickness of Perennial Ice Covers on Stratified Lakes of the Taylor Valley, Antarctica

    Science.gov (United States)

    Obryk, M. K.; Doran, P. T.; Hicks, J. A.; McKay, C. P.; Priscu, J. C.

    2016-01-01

    A one-dimensional ice cover model was developed to predict and constrain drivers of long term ice thickness trends in chemically stratified lakes of Taylor Valley, Antarctica. The model is driven by surface radiative heat fluxes and heat fluxes from the underlying water column. The model successfully reproduced 16 years (between 1996 and 2012) of ice thickness changes for west lobe of Lake Bonney (average ice thickness = 3.53 m; RMSE = 0.09 m, n = 118) and Lake Fryxell (average ice thickness = 4.22 m; RMSE = 0.21 m, n = 128). Long-term ice thickness trends require coupling with the thermal structure of the water column. The heat stored within the temperature maximum of lakes exceeding a liquid water column depth of 20 m can either impede or facilitate ice thickness change depending on the predominant climatic trend (temperature cooling or warming). As such, shallow (< 20 m deep water columns) perennially ice-covered lakes without deep temperature maxima are more sensitive indicators of climate change. The long-term ice thickness trends are a result of surface energy flux and heat flux from the deep temperature maximum in the water column, the latter of which results from absorbed solar radiation.

  16. The Importance of Temperature and Nitrogen Speciation on Bacterial Diversity in Stream Sediments in the McMurdo Dry Valleys

    Science.gov (United States)

    Baeseman, J. L.; Ward, B. B.

    2006-12-01

    Once called the Valleys of the Dead, the McMurdo Dry Valleys in Antarctica have been shown to harbor life that can withstand some of the coldest, windiest, driest and extreme conditions on Earth. The Dry Valleys are often referred to as `ecosystems waiting for water' because of the rapid response of biological activity when liquid water appears. Although our understanding of life in the Valleys is progressing, there are numerous unanswered questions about how the organisms survive there. Most of the attention in this delicate ecosystem has been focused on nematodes and lake and stream algal mat communities. Microbe abundances in stream sediments not associated with mats are only an order of a magnitude lower than those found in temporal streams. Yet very little is known about the metabolic capabilities, energy demands, nutrient requirements and genomes of these organisms. In December of 2004, sediment and water quality samples were collected from 19 streams in Taylor Valley. Bacterial DNA was extracted from the sediments and 16S rRNA amplified using 8f and 926r bacterial primers. Terminal Restriction Length Polymorphism (tRFLP) analysis was used to obtain community diversity fingerprints for all stream sites. The Bonney Basin had the most diverse bacterial assemblages on the basis of such fingerprints. There was no correlation between bacterial diversity and algal mat presence or absence, indicating that bacterial diversity does not depend on mats. Statistical analysis comparing water chemistry data and diversity indicates that temperature and nitrogen speciation and concentration are important factors contributing to diversity in these oligotrophic streams. Five clone libraries were sequenced and used to determine the major bacteria present in the streams. Approximately 15% of the sequences had less than a 97% similarity to any known bacterial sequence present in GenBank, suggesting a high incidence of bacterial species unique to the Dry Valleys. This research is

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

    DEFF Research Database (Denmark)

    Quintana, Catalina

    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...... found on steep slopes and in ravines. These areas of original dry valley vegetation preserve many wild relatives of cultivated plants on the one hand and old lineages of other wild plant groups. Dry inter-Andean valleys (DIAVs) in Ecuador therefore makeup a biodiversity hot spot for both plants...

  18. Biogeochemical and suspended sediment responses to permafrost degradation in stream banks in Taylor Valley, Antarctica

    Directory of Open Access Journals (Sweden)

    M. N. Gooseff

    2015-09-01

    Full Text Available Stream channels in the McMurdo Dry Valleys are typically wide, incised, and stable. At typical flows, streams occupy a fraction of the oversized channels, providing habitat for algal mats. In January 2012, we discovered substantial channel erosion and subsurface thermomechanical erosion undercutting banks of Crescent Stream. We sampled stream water along the impacted reach and compared concentrations of solutes to the long-term data from this stream (~20 years of monitoring. Thermokarst-impacted stream water demonstrated higher electrical conductivity, and concentrations of chloride, sulfate, sodium, suspended sediments, and nitrate than the long-term medians. These results suggest that this mode of lateral permafrost degradation may substantially impact stream solute loads and potentially fertilize stream and lake ecosystems. The potential for sediment to scour or bury stream algal mats is yet to be determined, though it may offset impacts of associated increased nutrient loads to streams.

  19. Deep groundwater and potential subsurface habitats beneath an Antarctic dry valley

    DEFF Research Database (Denmark)

    Mikucki, J. A.; Auken, E.; Tulaczyk, S.

    2015-01-01

    The occurrence of groundwater in Antarctica, particularly in the ice-free regions and along the coastal margins is poorly understood. Here we use an airborne transient electromagnetic (AEM) sensor to produce extensive imagery of resistivity beneath Taylor Valley. Regional-scale zones of low...... suitable for microbial life. These inferred brines are widespread within permafrost and extend below glaciers and lakes. One system emanates from below Taylor Glacier into Lake Bonney and a second system connects the ocean with the eastern 18km of the valley. A connection between these two basins...

  20. Sterile soil from Antarctica: organic analysis.

    Science.gov (United States)

    Horowitz, N H; Bauman, A J; Cameron, R E; Geiger, P J; Hubbard, J S; Shulman, G P; Simmonds, P G; Westberg, K

    1969-05-30

    Soils from the dry-valley region of Antarctica can be sterile by the usual microbiological criteria and yet contain significant amounts of organic carbon. Examination of one such soil shows that the organic material is finely divided anthracite coal. These findings have significant implications for the biological exploration of Mars.

  1. Coleoptera and microbe biomass in Antarctic Dry Valley paleosols adjacent to the Inland Ice: Implications for Mars

    Science.gov (United States)

    Mahaney, William C.; Hart, Kris M.; O'Reilly, Shane S.; Allen, Christopher C. R.; Dohm, James M.; Hancock, Ronald G. V.; Kelleher, Brian P.; Milner, Michael W.

    2012-01-01

    Bulk paleosol samples collected from a Middle to Early Miocene moraine in the New Mountain area of the Dry Valleys, Antarctica, yielded Coleoptera exoskeletons and occasional endoskeletons showing considerable diagenetic effects along with several species of bacteria, all lodged in a dry-frozen but salt-rich horizon at shallow depth to the land surface. The till is at the older end of a chronologic sequence of glacial deposits, thought to have been deposited before the transition from wet-based to cold-based ice (∼15 Ma), and hence, entirely weathered in contact with the subaerial atmosphere. It is possible, though not absolutely verifiable, that the skeletons date from this early stage of emplacement having undergone modifications whenever light snowmelt occurred or salt concentrations lowered the freezing temperature to maintain water as liquid. Correlation of the Coleoptera species with cultured bacteria in the sample and the likelihood of co-habitation with Beauveria bassiani found in two adjacent, although younger paleosols, leads to new questions about the antiquity of the Coleoptera and the source of N and glucose from chitinase derived from the insects. The skeletons in the 831 section may date close to the oldest preserved chitin (Oligocene) yet found on Earth. While harsh Martian conditions make it seemingly intolerable for complex, multicellular organisms such as insects to exist in the near-surface and subaerially, life within similar cold, dry paleosol microenvironments (Cryosols) of Antarctica point to life potential for the Red Planet, especially when considering the relatively diverse microbe (bacteria and fungi) population.

  2. 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...

  3. Microbial community composition of transiently wetted Antarctic Dry Valley soils

    Directory of Open Access Journals (Sweden)

    Thomas D. Neiderberger

    2015-01-01

    Full Text Available During the summer months, wet (hyporheic soils associated with ephemeral streams and lake edges in the Antarctic Dry Valleys (DV become hotspots of biological activity and are hypothesized to be an important source of carbon and nitrogen for arid DV soils. Recent research in the DV has focused on the geochemistry and microbial ecology of lakes and arid soils, with substantially less information being available on hyporheic soils. Here we determined the unique properties of hyporheic microbial communities, resolved their relationship to environmental parameters and to compared them to archetypal arid DV soils. Generally, pH increased and chlorophyll a concentrations decreased along transects from wet to arid soils (9.0 to ~7.0 for pH and ~0.8 to ~ 5 µg/cm3 for chlorophyll a, respectively. Soil water content decreased to below ~3% in the arid soils. Community fingerprinting-based principle component analyses revealed that bacterial communities formed distinct clusters specific to arid and wet soils; however, eukaryotic communities that clustered together did not have similar soil moisture content nor did they group together based on sampling location. Collectively, rRNA pyrosequencing indicated a considerably higher abundance of Cyanobacteria in wet soils and a higher abundance of Acidobacterial, Actinobacterial, Deinococcus/Thermus, Bacteroidetes, Firmicutes, Gemmatimonadetes, Nitrospira and Planctomycetes in arid soils. The two most significant differences at the genus level were Gillisia signatures present in arid soils and chloroplast signatures related to Streptophyta that were common in wet soils. Fungal dominance was observed in arid soils and Viridplantae were more common in wet soils. This research represents an in-depth characterization of microbial communities inhabiting wet DV soils. Results indicate that the repeated wetting of hyporheic zones has a profound impact on the bacterial and eukaryotic communities inhabiting in these areas.

  4. 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

    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 a...

  5. 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.

  6. Evidence for Repeated Early Miocene Glaciation and the Cutting of Upper Taylor Valley from the Friis Hills, Antarctica

    Science.gov (United States)

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

    2009-12-01

    The Friis Hills, located at the head of Taylor Valley in the the McMurdo Dry Valleys, hold a sequence of stacked tills at least Early Miocene in age. Sedimentology, clast lithology and bedrock striations indicate these tills were deposited from wet-based glaciers that flowed southeastward down a shallow paleovalley toward the Ferrar trough. Interbedded paleosols, fluvial, and glaciolacustrine deposits register ice-free periods when the valley held small streams and ponds. Exceptionally well-preserved fossil biota suggests mild conditions during at least two of these interglacial episodes. Proglacial lacustrine deposits that include dropstones and debris flows mark the return of glacial conditions but fossil leaves and wood of Nothofagus suggest conditions during the initial phase of ice advance were also relatively mild. Geomorphic relationships show that major valley incision must have taken place after deposition of these sediments as the Friis Hills is today a flat-topped inselberg, about 5 km across, isolated from nearby topography by the deep glacial troughs of the Taylor Valley drainage. A second suite of tills, directly overlying the first, registers a reorganized glacial system with ice streaming eastward, roughly parallel to Taylor Valley. Like the first, these tills were deposited during repeated ice advances but glaciers never fully inundated the Friis Hills and ice-free periods are marked by only weak weathering surfaces and thin glaciolacustrine deposits. We interpret the changing glacial pattern to reflect headward cutting in upper Taylor Valley and the capture of ice from the Ferrar drainage. A volcanic ash interbed dated by Ar-Ar at 19.76 (±0.11) Ma occurs in a Taylor Valley-oriented drift near the eastern edge of the Friis Hills plateau. Based on its stratigraphic position, the older suite of tills and fossil-bearing interbeds are >19.76 Ma. Underlying bedrock striations show that ice flow had been redirected into Taylor Valley by this time. The

  7. Detailed Aggregate Resources Study, Dry Lake Valley, Nevada.

    Science.gov (United States)

    1981-05-29

    the north-central patt of the valley. E Ertec E-TR-47-DL 12 3.0 ROAD-BASE AGGREGATES EVALUATION 3.1 STUDY APROACH The primary objective of the road-base...HARDENED CEMENT MORTAR AND CONCRETE go 60 C173 AIR CONTENT OF CONCRETE. VOLUMETRIC METHOD 9 6 W_ C192 MAKING AND CURING CONCRETE SPECIMENS 9 6 I- C227...POTENTIAL ALKALI-SILICA REACTIVITY. MORTAR-BAR METHOD am I up) 8 ~STATIC MODULUS OF ELASTICITY. POISSONS RATIO OF CONCRETE ____ IN COMPRESSION 72 48

  8. 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...

  9. Field station for dry-hot valley ecosystem in the pipeline

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ A panel of experts recently gave the nod to a proposal and feasibility study to set up a research station for monitoring the dry-hot valley ecosystem in Yuanjiang of southwest China's Yunnan Province. The proposal was presented by the CAS Xishuangbannan Tropical Botanical Garden.

  10. 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......, suggesting low migration rates due to local barriers. We identified seven species distribution patterns that gave rise to high β-diversity in the dry inter-Andean valleys. The β-diversity of trees was the lowest. Herbs had the highest β-diversity, which increased steadily with geographic distance. Our...... results further highlight the influence of disturbance, water availability and low temperature on plant species composition and occurrence. We also found significant, contrasting patterns in responses to environmental drivers, when analyzing our data separately by life form. Our results show...

  11. A magmatic mush column rosetta stone: The McMurdo Dry Valleys of Antarctica

    Science.gov (United States)

    Marsh, Bruce

    2004-11-01

    A long-running mystery of Earth science concerns the physical and dynamic connection between volcanism, plutonism, magma chambers, layered intrusions, and the production from mantle material of oceanic and continental crust. The basic chemical connection of fractionating melt from crystals and resorting crystals again and again is clear, but volcanologists and plutonists covet almost mutually exclusive, process-oriented sciences to explain the compositional sequences and textures found in stacks of lavas and expanses of plutons. Lavas present an extensive time series of quenched aliquots of magma without any clear measure of the evolutionary spatial context of sampling within the magmatic system. Plutons offer extensive spatial context without a clear physical connection to the greater active magmatic system and without a sequential capturing of time; critical original textural details are erased under long cooldown times. A deadly middle ground must be crossed to meld the timescales and textures captured by volcanism with the spatial scales and textural processes of plutonism into a conceptual representation of an integrated working magmatic system.

  12. Dissolved gases in perennially ice-covered lakes of the McMurdo Dry Valleys, Antarctica

    Science.gov (United States)

    Andersen, D. T.; McKay, C. P.; Wharton, R. A. Jr; Wharton RA, J. r. (Principal Investigator)

    1998-01-01

    Measurements of dissolved N2, O2, Ar, CO2, and CH4 were made in perennially ice-covered Lake Hoare. Results confirm previous reports that O2 concentrations in the upper water column exceed atmospheric equilibrium and that N2 and Ar are supersaturated throughout the water column. The mean supersaturation of N2 was found to be 2.0 (+/- 0.37) and Ar was 3.8 (+/- 1.1). The ratios of N2/Ar (20.3 +/- 13.8), and O2/Ar (22.5 +/- 4.0) at the ice-water interface are consistent with those previously measured, suggesting that bubble formation is the main process for removing gas from the lake. However, the saturations of N2 and Ar greatly exceed those previously predicted for degassing by bubble formation only at the ice-water interface. The data support the hypothesis that removal of gas by bubbles occurs in the water column to a depth of 11 m in Lake Hoare. CO2 concentration increases from near zero at the ice-water interface to 80-100 times saturation at and below the chemocline at c. 28 m. There is considerable variability in the gas concentrations throughout the water column; samples separated in depth by one metre may vary by more than 50% in gas content. It is likely that this phenomenon results from the lack of turbulent mixing in the water column. Methane (c. 2 micrograms l-1) was detected below the chemocline and immediately above the sediment/water interface at a depth of 30 m. Samples from lakes Vanda, Joyce, and Miers, also show supersaturations of O2, N2, and Ar at levels similar to levels found in Lake Hoare.

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

    Science.gov (United States)

    Vishniac, H. S.

    1982-01-01

    The success of the Antarctic Dry Valley yeasts presumeably results from adaptations to multiple stresses, to low temperatures and substrate-limitation as well as prolonged resting periods enforced by low water availability. Previous investigations have suggested that the crucial stress is substrate limitation. Specific adaptations may be pinpointed by comparing the physiology of the Cryptococcus vishniacii complex, the yeasts of the Tyrol Valley, with their congeners from other habitats. Progress was made in methods of isolation and definition of ecological niches, in the design of experiments in competition for limited substrate, and in establishing the relationships of the Cryptococcus vishniacii complex with other yeasts. In the course of investigating relationships, a new method for 25SrRNA homology was developed. For the first time it appears that 25SrRNA homology may reflect parallel or convergent evolution.

  14. Solar-forced roughening of Antarctic glaciers and the Martian icecaps: How surficial debris and roughness affect glacial melting in Taylor Valley, Antarctica and how this can be applied to the Martian icecaps

    Science.gov (United States)

    Lewis, Karen Jane

    Glaciers in the McMurdo Dry Valleys of Antarctica exhibit significant variations in surface roughness from smooth surfaces to large basins and canyon up to 15 meters deep and 100 meters across. The walls defining these basins and canyons show a consistent asymmetry, with near-vertical slopes facing the direction of maximum irradiance (north) and slopes of 30 to 40 degrees otherwise. Energy balance and modeling studies presented here show that these features generate their own microclimate. The radiation and turbulent terms of the energy balance within the basins differ significantly from those on adjacent horizontal surfaces. Radiation absorption within the basins is also strongly affected by basin geometry, with increased radiation on the north facing walls and reduced radiation on the south facing slopes relative to adjacent horizontal surfaces. Averaged over an entire basin, these variations in radiation receipt result in increased melt from the basins as compared with adjacent horizontal surfaces. The basins and canyons appear to evolve from patches of surficial debris. To support this hypothesis, results from dust plot experiments and modeling of cryoconite hole growth are presented. Experiment results highlight the effects of debris on surface energy balance. The modeling indicates that evolution of cryoconite holes is slow as long as the holes are ice-covered. Holes of a meter or more in diameter with no ice cover can rapidly deepen, developing a geometry similar to that of the large basins. The dry valleys environment may serve as a terrestrial analogue for the Martian icecaps. The Martian icecaps exhibit two types of roughness features: large troughs of up to 100 km in length, 10 km wide and a kilometer deep that incise both the north and south polar residual caps, and "swiss-cheese" terrain, fields of circular basins 10 m deep and 100 m across found on the south polar residual cap near 87°S. Comparison of the Martian trough and basin features with

  15. Drivers of ASCAT C band backscatter variability in the dry snow zone of Antarctica

    NARCIS (Netherlands)

    Fraser, Alexander D.; Nigro, Melissa A.; Ligtenberg, Stefan R. M.; Legresy, Benoit; Inoue, Mana; Cassano, John J.; Munneke, Peter Kuipers; Lenaerts, Jan T. M.; Young, Neal W.; Treverrow, Adam; Van Den Broeke, Michiel; Enomot, Hiroyuki

    2016-01-01

    C band backscatter parameters contain information about the upper snowpack/firn in the dry snow zone. The wide incidence angle diversity of the Advanced Scatterometer (ASCAT) gives unprecedented characterisation of backscatter anisotropy, revealing the backscatter response to climatic forcing. The A

  16. 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.

  17. 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

  18. Livelihood Capital and Livelihood Diversification for Different Farmers in Yuanjiang Dry- Hot River Valley

    Institute of Scientific and Technical Information of China (English)

    Wenjuan ZHAO; Shilong YANG; Xiao WANG

    2016-01-01

    Under the analytical framework of sustainable livelihoods,we establish the evaluation indicator system for farmers’ livelihood capital,to evaluate the current livelihood capital and livelihood diversification for different farmers in the Dai nationality region of Xinping County in the Yuanjiang dry-hot river valley area,and discuss the relationship between livelihood capital and livelihood diversification. Studies have shown that the mode dominated by agriculture,supplemented by non-agricultural activities,combined with breeding,is the commonly used livelihood strategy for farmers in this region. As farmers change from pure agriculture to non-agriculture,their total livelihood capital and nonagricultural livelihood diversification index will increase,while agricultural livelihood diversification index will decrease. In the meantime,their livelihood activities gradually shift from agricultural to non-agricultural ones,which is mainly reflected in the combination of both agricultural and non-agricultural activities. Regression analysis on livelihood capital and livelihood diversification shows that natural and physical capital is the basis of realizing agricultural livelihood diversification. Farmers with rich natural and physical capital will prefer agricultural livelihood strategies. While financial and human capital is the driving force for farmers’ transition from pure agriculture to non-agriculture.

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

    OpenAIRE

    2014-01-01

    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 decre...

  20. 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

  1. Antarctic Dry Valleys: Geological Processes in Hyperarid, Hypothermal Environments and Implications for Water on Mars

    Science.gov (United States)

    Head, J.; Dickson, J. L.; Levy, J. S.; Baker, D. M. H.; Marchant, D. R.

    2012-04-01

    The Antarctic Dry Valleys (ADV) are characterized by mean annual temperatures (MAT) well below the freezing point of water and are among the coldest and driest environments on Earth. In spite of these extreme conditions, seasonal temperatures (ST) and peak daytime temperatures (PDT) can locally exceed the melting point of water in certain settings in certain microenvironments. Three major microenvironments (upland stable zone, inland mixed zone, coastal thaw zone) are defined in the ADV on the basis of measurements of atmospheric temperatures (MAT/ST), soil moisture and relative humidity, and the concurrent availability and mobility of water; these microenvironments show variations in the abundance and character of different geomorphic features. For example, in the coldest upland stable zone melting is almost non-existent and sublimation polygons dominate; ice-wedge polygons occur in the coastal thaw zone where seasonal temperatures can exceed the melting temperature of water; sand-wedge polygons occur in the inland mixed zone. The ADV are characterized by a regional permafrost layer and a shallow ice table. In contrast to more temperate latitudes on Earth where the hydrological system and cycle are vertically integrated, the ADV hydrological system consists of a horizontally stratified hydrological cycle; the regional permafrost layer precludes vertical exchange of surface water and deep groundwater below the permafrost. Local near-surface meltwater is produced seasonally, flows across the surface to create gullies, channels and small fluvial features, and soaks into the dry upper part of the permafrost, running downslope along the top of the ice table in a perched aquifer. In this context, melting of seasonal and perennial surface and very near surface snow and ice deposits during peak seasonal and peak daytime temperatures causes a range of fluvial and liquid water-related features in the coastal thaw zone and inland mixed zone. Among the features and processes

  2. Meteoric Be-10 from Sirius Group suggests high elevation McMurdo Dry Valleys permanently frozen since 6 Ma

    DEFF Research Database (Denmark)

    Dickinson, Warren W.; Schiller, Martin; Ditchburn, Bob G.

    2012-01-01

    A long-standing debate concerning Neogene Antarctic climate in the McMurdo Dry Valleys relies largely on evidence from landscape evolution, glacial modeling and stratigraphy. We provide new evidence from meteoric Be for the onset of frozen, hyper-arid conditions on a high elevation (1840m......) interfluve at Table Mountain. A simple decay model for the co-occurrence of meteoric Be and illuviated clay in cores of ice-cemented glacial sediments indicates that the clays were actively migrating down from the surface in a warm climate until the system froze between 6 and 9Ma. Although this age range may...

  3. Chemical weathering trends in fine-grained ephemeral stream sediments of the McMurdo Dry Valleys, Antarctica

    Science.gov (United States)

    Marra, Kristen R.; Elwood Madden, Megan E.; Soreghan, Gerilyn S.; Hall, Brenda L.

    2017-03-01

    We investigated chemical weathering trends within the fine-grained ( 40 m2/g. Utilization of MFW (mafic-felsic-weathered) and A-CN-K (Al2O3-CaO + Na2O-K2O) plots, however, are more effective in discerning the extent and nature of chemical weathering in these stream systems. Ca and Na depletion observed within the sediments exhibiting the highest surface area in Delta Stream suggest that chemical weathering may result in pitting and/or incongruent dissolution of pyroxenes and feldspars, as well as the development of amorphous and/or nanophase weathering products. In contrast, Clark Glacier stream sediments do not have similar leaching trends in the fine-grained sediment fraction and exhibit minimal weathering overall. This may suggest that fine-grained material is being trapped on top of the Clark Glacier surface and has not yet been transported into the weathering environment of the hyporheic zone due to timing of sampling. Alternatively, complete dissolution of very fine-grained sediment could be occurring in this stream transect, and is therefore not preserved in the fine sediment fraction. Overall, the magnitude of chemical weathering observed between the two stream systems is ultimately related to the nature of the underlying drift (cold and wet-based drift deposition), dispersal patterns of eolian fines, and variable stream discharge rates. Thus, incorporation of local fine-grained sediment derived from the underlying glacial drift deposits and distributed via the varying wind regimes within the hyper-arid climate into active stream channels may facilitate incongruent mineral dissolution and development of weathering products, and ultimately influence the composition and concentration of meltwater stream solutes.

  4. Preliminary Study on Biological Characteristics of Degraded Soil Ecosystems in Dry Hot Valley of the Jinsha River

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Distribution characteristics of soil animals, microorganisms and enzymatic activity were studied in thedry red soil and Vertisol ecosystems with different degradation degrees in the Yuanmou dry hot valley of theJinsha River, China. Results showed that Hymenoptera, Araneae and Collembola were the dominant groupsof soil animals in the plots studied. The numbers of groups and individuals and density of soil animals in thedry red soil series were higher than those in the Vertisol series, and the numbers of individuals and density ofsoil animals decreased with the degree of soil degradation. Bacteria dominated microbiocoenosis not only inthe dry red soils but also in the Vertisols. Microbial numbers of the dry red soil series were higher than thoseof Vertisol series, and decreased with the degree of soil degradation. The activities of catalase, invertase,urease and alkaline phosphatase declined with the degradation degree and showed a significant decline withdepth in the profiles of both the dry red soils and the Vertisols, but activities of polyphenol oxidase andacid and neutral phosphatase showed the same tendencies only in the Vertisols. It was concluded that thecharacteristics of soil animals, microorganisms and enzymatic activity could be used as the bio-indicators toshow the degradation degree of the dry red soils and Vertisols. Correlation among these soil bio-indicatorswas highly significant.

  5. Meteoric Be-10 from Sirius Group suggests high elevation McMurdo Dry Valleys permanently frozen since 6 Ma

    Science.gov (United States)

    Dickinson, Warren W.; Schiller, Martin; Ditchburn, Bob G.; Graham, Ian J.; Zondervan, Albert

    2012-11-01

    A long-standing debate concerning Neogene Antarctic climate in the McMurdo Dry Valleys relies largely on evidence from landscape evolution, glacial modeling and stratigraphy. We provide new evidence from meteoric 10Be for the onset of frozen, hyper-arid conditions on a high elevation (1840 m) interfluve at Table Mountain. A simple decay model for the co-occurrence of meteoric 10Be and illuviated clay in cores of ice-cemented glacial sediments indicates that the clays were actively migrating down from the surface in a warm climate until the system froze between 6 and 9 Ma. Although this age range may be sensitive to possible interference by in situ produced 10Be, the implied minimum age of 6 Ma for the Sirius Group indicates that the Dry Valleys were permanently frozen down to this elevation at this time. The model also suggests denudation rates of 1-6 cm Myr-1 since freezing. These data provide an independent test of glacial-stratigraphic evidence used to determine Antarctic paleoclimate.

  6. Hydrological Controls on Ecosystem Dynamics in Lake Fryxell, Antarctica.

    Directory of Open Access Journals (Sweden)

    Radu Herbei

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

  7. Cold-active halophilic bacteria from the ice-sealed Lake Vida, Antarctica.

    Science.gov (United States)

    Mondino, Lindsay J; Asao, Marie; Madigan, Michael T

    2009-10-01

    Lake Vida is a large, permanently ice-covered lake in the Victoria Valley of the McMurdo Dry Valleys, Antarctica and is unique among Dry Valley lakes because it is ice-sealed, with an ice-cover of nearly 19 m. Enrichment cultures of melt-water from Lake Vida 15.9 m ice yielded five pure cultures of aerobic, heterotrophic bacteria. Of these, one strain grew at -8 degrees C and the four others at -4 degrees C. All isolates were either halotolerant or halophilic, with two strains capable of growth at 15% NaCl. Phylogenetic analysis revealed the Lake Vida isolates to be Gammaproteobacteria, related to species of Psychrobacter and Marinobacter. This is the first report of pure cultures of bacteria from Lake Vida, and the isolates displayed a phenotype consistent with life in a cold hypersaline environment.

  8. 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.

  9. 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.

  10. Evaluation of WRF PBL parameterization schemes against direct observations during a dry event over the Ganges valley

    Science.gov (United States)

    Sathyanadh, Anusha; Prabha, Thara V.; Balaji, B.; Resmi, E. A.; Karipot, Anandakumar

    2017-09-01

    Accurate representations of the planetary boundary layer (PBL) are important in all weather forecast systems, especially in simulations of turbulence, wind and air quality in the lower atmosphere. In the present study, detailed observations from the Cloud Aerosol Interaction and Precipitation Enhancement Experiment - Integrated Ground based Observational Campaign (CAIPEEX-IGOC) 2014 comprising of the complete surface energy budget and detailed boundary layer observations are used to validate Advanced Research Weather Research and Forecasting (WRF) model simulations over a diverse terrain over the Ganges valley region, Uttar Pradesh, India. A drying event in June 2014 associated with a heat wave is selected for validation.Six local and nonlocal PBL schemes from WRF at 1 km resolution are compared with hourly observations during the diurnal cycle. Near-surface observations of weather parameters, radiation components and eddy covariance fluxes from micrometeorological tower, and profiles of variables from microwave radiometer, and radiosonde observations are used for model evaluations. Models produce a warmer, drier surface layer with higher wind speed, sensible heat flux and temperature than observations. Layered boundary layer dynamics, including the residual layer structure as illustrated in the observations over the Ganges valley are missed in the model, which lead to deeper mixed layers and excessive drying.Although it is difficult to identify any single scheme as the best, the qualitative and quantitative analyses for the entire study period and overall reproducibility of the observations indicate that the MYNN2 simulations describe lower errors and more realistic simulation of spatio-temporal variations in the boundary layer height.

  11. Changes of seasonally dry forest in the Colombian Patía Valley during the early and middle Holocene and the development of a dry climatic record for the northernmost Andes

    NARCIS (Netherlands)

    Z. González-Carranza; J.C. Berrío; H. Hooghiemstra; J.F. Duivenvoorden; H. Behling

    2008-01-01

    A 450 cm long sediment core was collected from a swamp in the dry forest ecosystem of the Patía Valley in Colombia (02°02′ N, 77° W at 750 m elevation). This core (Potrerillo-2) was analysed using pollen, lithostratigraphy and radiocarbon dates and was correlated with an already existing dataset fro

  12. Single-grain and multigrain luminescence dating of on-ice and lake-bottom deposits at Lake Hoare, Taylor Valley, Antarctica

    DEFF Research Database (Denmark)

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

    2010-01-01

    The large radiocarbon (14C) reservoir effect in Antarctica varies regionally and with settings. Luminescence sediment dating has potential as an alternate geochronometer. Extending our earlier tests of the effectiveness of resetting of photon-stimulated-luminescence (PSL) that employed only multi...

  13. Slope streaks in the Antarctic Dry Valleys: Characteristics, candidate formation mechanisms, and implications for slope streak formation on Mars

    Science.gov (United States)

    Head, J. W.

    2007-12-01

    Slope streaks on Mars are typically dark, extend downslope for up to ~2 km, are relief, and have been observed to form and change over less than decadal time periods. Mars slope streaks occur exclusively in regions of low thermal inertia, steep slopes, and only where peak temperatures exceed 275 K; changes are observed only if the interval includes the warm season. Mechanisms proposed for Mars slope streaks include dry dust avalanches, dust avalanches controlled by wind, wet debris flows, both wet and dry debris flows, and erosive fluvial processes from spring discharge, where melting is aided by hydrothermal activity or hypersaline aquifers. Although the ADV represent one of the most Mars-like terrestrial environments, there are also substantial differences (e.g., atmospheric pressure and composition; abundance of water, etc.) and thus analogs must be assessed cautiously. We investigated very similar slope streaks in upper Wright Valley of the Antarctic Dry Valleys and interpret their formation to be due to snowpack and near-surface melting-derived saline water traveling downslope along the top of the ice table, wicking upward, and dampening the surface to cause the streak. Among the observations of Mars streaks that suggest that this mechanism should be seriously considered are: 1) similarities in characteristics, brightness, scales, slopes, aspect ratio, temporal behavior, and modes of occurrence; 2) distribution and geometry of occurrence suggesting a relation to solar insolation (low latitudes and northernmost streaks occur preferentially on warmer south-facing slopes); 3) the observation that they occur only where peak temperatures exceed 275 K, and that changes occur only where there has been an intervening warm season, suggesting a potential role for the melting of surface snow and ice. We thus conclude that the saline-assisted surface-near surface melting and water migration origin of slope streaks interpreted from the ADV should be further assessed as a

  14. Astronomy in Antarctica

    CERN Document Server

    Burton, Michael G

    2010-01-01

    Antarctica provides a unique environment for astronomy. The cold, dry and stable air found above the high plateau, as well as the pure ice below, offers new opportunities across the photon & particle spectrum. The summits of the plateau provide the best seeing conditions, the darkest skies and the most transparent atmosphere of any earth-based observing site. Astronomical activities are now underway at four plateau sites: the Amundsen-Scott South Pole Station, Concordia Station at Dome C, Kunlun Station at Dome A and Fuji Station at Dome F, in addition to long duration ballooning from the coastal station of McMurdo. Astronomy conducted includes optical, IR, THz & sub-mm, measurements of the CMBR, solar, as well as high energy astrophysics involving measurement of cosmic rays, gamma rays and neutrinos. Antarctica is also the richest source of meteorites on our planet. An extensive range of site testing measurements have been made over the high plateau. We summarise the facets of Antarctica that are dri...

  15. [Eco-anatomical characteristics of Sophora davidii leaves along an elevation gradient in upper Minjiang River dry valley].

    Science.gov (United States)

    Li, Fanglan; Bao, Weikai; Liu, Junhua; Wu, Ning

    2006-01-01

    This paper studied the eco-anatomical characteristics of Sorphora davidii leaves at the elevations of 1,650, 1,750, 1,850 and 1,950 m in the upper reaches of Minjiang River dry valley. The indices investigated were leaf length (LL), leaf width (LW), LL/ LW, leaf area, leaf thickness, leaf epidermal thickness, leaf palisade mesophyll thickness (P), leaf spongy mesophyll thickness (S), P/S, leaf cutin membrane thickness, leaf stomatal density and area, leaf epidermis cell density and area, and leaf pubescence length and density. The results showed that the leaves of S. davidii were elliptic, with an area 0.144 approximately 0.208 cm2 and a thickness 171.58 approximately 195.83 microm. The mesophyll was significantly differentiated into palisade and spongy. The thickness of palisade mesophyll was 69.83 approximately 82.42 microm, that of spongy mesophyll was 62.00 approximately 80.67 microm, and P/S was 1.14 approximately 1.01. Upper epidermal thickness was 14.03 approximately 15.33 microm, while lower epidermal thickness was 13.88 approximately 16.17 microm. The stomatal density, stomatal area, epidermis cell density, epidermis cell area, pubescence length, and pubescence density were 13.71 approximately 15.02 mm(-2), 249.86 approximately 280.43 microm2, 160.54 approximately 178.43 mm(-2), 557.43 approximately 626.85 microm2, 186.51 approximately 260.99 microm, and 18.29 approximately 32.27 mm(-2), respectively. With increasing elevation, the leaf area, leaf thickness, palisade mesophyll thickness, spongy mesophyll thickness, stomatal area, epidermis cell area and pubescence density were increased, while cutin membrane thickness, epidermis cell density, pubescence length, and stomatal density were decreased. There was no significant difference in LL/LW, P/S, epidermal thickness and stomatal density along the elevation gradient.

  16. 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.``

  17. 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

  18. Radiometric 81Kr dating identifies 120,000-year-old ice at Taylor Glacier, Antarctica

    OpenAIRE

    Buizert, Christo; Baggenstos, Daniel; Jiang, Wei; Purtschert, Roland; Petrenko, Vasilii V.; Lu, Zheng-Tian; Müller, Peter; Kuhl, Tanner; Lee, James,; Severinghaus, Jeffrey P.; Brook, Edward J.

    2014-01-01

    We present the first successful 81Kr-Kr radiometric dating of ancient polar ice. Krypton was extracted from the air bubbles in four ~350 kg polar ice samples from Taylor Glacier in the McMurdo Dry Valleys, Antarctica, and dated using Atom Trap Trace Analysis (ATTA). The 81Kr radiometric ages agree with independent age estimates obtained from stratigraphic dating techniques with a mean absolute age offset of 6 +/- 2.5 ka. Our experimental methods and sampling strategy are validated by 1) 85Kr ...

  19. Study on Photosynthesis Characters of Tamarindus indica L.in Dry Season in Yuanmou Dry-hot Valley%元谋干热河谷罗望子旱季光合特性研究

    Institute of Scientific and Technical Information of China (English)

    潘志贤; 杨艳鲜; 方海东; 彭辉; 岳学文; 钱坤建; 纪中华

    2011-01-01

    ln order to analyze the photosynthesis characters of Tamarindus indica L . in dry-hot valley, The Pn, Gs and other indexea were studied in the dry season in Yuanmou county. The results ahowed that the diumal course of Pn presented a single peak cutve and did not showed the midday depression of photoaynthesis. There was a positive correlation between Pn and PAR , the same correlation between pn , Tr, Gs and VPD. There was a negative correlation between Pn and RH. Pn was more affected by PAR than other factors. In sum the Tamarind was stmngly adapted to planting in dry-hot valley.%通过对罗望子的光合速率、气孔导度及其相应环境因子的测定,探讨元谋干热河谷罗望子旱季的光合生理生态特征.结果表明,罗望子旱季的光合速率Pn日变化曲线呈单蜂型,无光合"午休"现象发生.Pn与PAR、Tr呈极显著正相关,与RH呈极显著负相关.对Pn影响最大的因子PAR,其次是RH、Tr、Gs、VPD.罗望子在元谋干热河谷有较强的适应性.

  20. Provenance, environmental and paleogeographic controls on sandstone composition in an incised-valley system: the Eocene La Meseta Formation, Seymour Island, Antarctica

    Science.gov (United States)

    Marenssi, Sergio A.; Net, Laura I.; Santillana, Sergio N.

    2002-07-01

    The Eocene La Meseta Formation is the youngest exposed unit of the back-arc James Ross Basin, Antarctic Peninsula, cropping out in Seymour (Marambio) Island. The formation comprises 720 m of clastic sedimentary rocks of deltaic, estuarine and shallow marine origin. It was subdivided into six unconformity-based units (Valle de Las Focas, Acantilados, Campamento, Cucullaea I, Cucullaea II and Submeseta Allomembers) grouped into three main facies associations. Facies association I represents valley-confined deposition in a progradational/aggradational tide-dominated and wave-influenced delta front/delta plain environment. Facies association II includes tidal channels, mixed tidal flats, tidal inlets and deltas, washover and beach environments. Facies association III represents nonconfined tide- and storm-influenced nearshore environments. La Meseta Formation sandstones are quartzofeldspathic with some hybrid arenites (glauconite and carbonate bioclasts-rich). Sandstone detrital modes are subdivided into two distinctive petrofacies: the low quartz petrofacies (petrofacies I, Q12%), interpreted to retain the original provenance signal, and the high quartz petrofacies (petrofacies II, Q>55% and L1.4) is clearly dominated by volcanic-derived clasts; it developed at times of high sea level and/or during later stages of the valley fill, when an "energy fence" at the shoreline prevented delivery of sediment from the Antarctic Peninsula, thus enhancing the relative participation of local volcanic sources.

  1. Hello Antarctica

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    China has made 25 expeditions to the Antarctic over a quarter century Exactly 17,501.949 km-that’s the distance from Beijing to Changcheng (lit-erally meaning the Great Wall) Station,the first little piece of China on the continent of Antarctica. Twenty-five years ago, when the country was conceiving its first journey to the South Pole, that distance meant nothing

  2. Vapor transport and sublimation on Mullins Glacier, Antarctica

    Science.gov (United States)

    Lamp, J. L.; Marchant, D. R.

    2017-05-01

    We utilize an environmental chamber capable of recreating the extreme polar conditions of the McMurdo Dry Valleys (MDV) of Antarctica to investigate the sublimation rate of the Mullins Valley debris-covered glacier (hereafter Mullins Glacier), reportedly one of the oldest debris-covered alpine glaciers in the world. We measure ice loss via sublimation beneath sediment thicknesses ranging from 0 to 69 mm; from this, we determine an effective diffusivity for Fickian vapor transport through Mullins till of (5.2 ± 0.3) ×10-6 m2s-1 at -10 °C. We use this value, coupled with micrometeorological data from Mullins Valley (atmospheric temperature, relative humidity, and soil temperature) to model the sublimation rate of buried glacier ice near the terminus of Mullins Glacier, where the overlying till thickness approaches 70 cm. We find that the ice-lowering rate during the modeled year (2011) was 0.066 mm under 70 cm of till, a value which is in line with previous estimates for exceedingly slow rates of ice sublimation. These results provide further evidence supporting the probable antiquity of Mullins Glacier ice and overall landscape stability in upland regions of the MDV.

  3. 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.

  4. Surface winds over West Antarctica

    Science.gov (United States)

    Bromwich, David

    1993-01-01

    Five winter months (April-August 1988) of thermal infrared satellite images were examined to investigate the occurrence of dark (warm) signatures across the Ross Ice Shelf in the Antarctic continent. These features are inferred to be generated by katabatic winds that descend from southern Marie Byrd Land and then blow horizontally across the ice shelf. Significant mass is added to this airstream by katabatic winds blowing from the major glaciers that flow through the Transantarctic Mountains from East Antarctica. These negatively buoyant katabatic winds can reach the northwestern edge of the shelf - a horizontal propagation distance of up to 1,000 km - 14 percent of the time. Where the airstream crosses from the ice shelf to the ice-covered Ross Sea, a prominent coastal polynya is formed. Because the downslope buoyancy force is near zero over the Ross Ice Shelf, the northwestward propagation of the katabatic air mass requires pressure gradient support. The study shows that the extended horizontal propagation of this atmospheric density current occurred in conjunction with the passage of synoptic cyclones over the southern Amundsen Sea. These cyclones can strengthen the pressure gradient in the interior of West Antarctica and make the pressure field favorable for northwestward movement of the katabatic winds from West Antarctica across the ice shelf in a geostrophic direction. The glacier winds from East Antarctica are further accelerated by the synoptic pressure gradient, usually undergo abrupt adjustment beyond the exit to the glacier valley, and merge into the mountain-parallel katabatic air mass.

  5. UAV Antarctica

    OpenAIRE

    Dahl, David; Stetler, Fredrik

    2014-01-01

    One of the biggest problems of our time is the global warming. A direct result of this phenomena is the melting of ice of the glaciers on the north and the south pole. As this continues, the melted ice will contribute to an increase of the sea level, and may cause enormous natural disasters. To be able to prevent this, it’s important to study its affects. This reports contains a concept study of a Unmanned Aerial Vehicle, a UAV, set on the coast of Antarctica by the Australian owned base Davi...

  6. 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.

  7. Cold-Active, Heterotrophic Bacteria from the Highly Oligotrophic Waters of Lake Vanda, Antarctica

    Directory of Open Access Journals (Sweden)

    Nicole A. Vander Schaaf

    2015-07-01

    Full Text Available The permanently ice-covered lakes of the McMurdo Dry Valleys, Antarctica are distinctive ecosystems that consist strictly of microbial communities. In this study, water samples were collected from Lake Vanda, a stratified Dry Valley lake whose upper waters (from just below the ice cover to nearly 60 m are highly oligotrophic, and used to establish enrichment cultures. Six strains of psychrotolerant, heterotrophic bacteria were isolated from lake water samples from a depth of 50 or 55 m. Phylogenetic analyses showed the Lake Vanda strains to be species of Nocardiaceae, Caulobacteraceae, Sphingomonadaceae, and Bradyrhizobiaceae. All Lake Vanda strains grew at temperatures near or below 0 °C, but optimal growth occurred from 18 to 24 °C. Some strains showed significant halotolerance, but no strains required NaCl for growth. The isolates described herein include cold-active species not previously reported from Dry Valley lakes, and their physiological and phylogenetic characterization broadens our understanding of these limnologically unique lakes.

  8. Marine ice sheet collapse and terrestrial climate stability in Pliocene East Antarctica

    Science.gov (United States)

    Hill, Daniel; Smith, Yvonne

    2016-04-01

    New marine evidence is emerging of ice sheet collapses in vulnerable marine basins of the East Antarctica during warm periods of the Pliocene. This contrasts the long-standing terrestrial evidence from the Dry Valleys and wider Transantarctic Mountains, showing landscape and climatic stability since the middle Miocene. This terrestrial evidence has been used to infer that the East Antarctic Ice Sheet has been large and in a similar state to today for at least 10 million years. Here we present a series of sensitivity experiments using the HadCM3 General Circulation Model, simulating the impact of ice sheet retreats on Pliocene climate. Major collapses in the marine basins cause changes in the atmospheric circulation around East Antarctica and propagate warmer and wetter air masses into the interior of the ice sheet. However, remaining areas of upland ice sheet act to protect areas of the interior from increases in temperature and precipitation. Only when ice retreats from the upland areas between the subglacial basins and the Transantarctic Mountains of Northern Victoria Land are the Dry Valleys exposed to mean summer temperatures significantly above freezing and the full increases in modelled precipitation. This suggests that collapses of the marine portions of the Wilkes Subglacial Basin and Aurora Subglacial Basin would not have significantly altered the palaeoenvironmental record of the Dry Valleys. These results provide a reconciliation of the records of East Antarctic ice sheet retreat and climate stability and further corroborate the findings from marine cores. We also present the results of an iceberg modelling study that shows that observed losses of Wilkes Land IRD in the Prydz Bay region cannot be explained by climate induced changes in melting or iceberg trajectory, but probably requires the loss of the marine margin of the Wilkes Land sector of the East Antarctic Ice Sheet.

  9. 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.

  10. Landscape evolution of Antarctica

    Science.gov (United States)

    Jamieson, S.S.R.; Sugden, D.E.

    2007-01-01

    The relative roles of fluvial versus glacial processes in shaping the landscape of Antarctica have been debated since the expeditions of Robert Scott and Ernest Shackleton in the early years of the 20th century. Here we build a synthesis of Antarctic landscape evolution based on the geomorphology of passive continental margins and former northern mid-latitude Pleistocene ice sheets. What makes Antarctica so interesting is that the terrestrial landscape retains elements of a record of change that extends back to the Oligocene. Thus there is the potential to link conditions on land with those in the oceans and atmosphere as the world switched from a greenhouse to a glacial world and the Antarctic ice sheet evolved to its present state. In common with other continental fragments of Gondwana there is a fluvial signature to the landscape in the form of the coastal erosion surfaces and escarpments, incised river valleys, and a continent-wide network of river basins. A selective superimposed glacial signature reflects the presence or absence of ice at the pressure melting point. Earliest continental-scale ice sheets formed around 34 Ma, growing from local ice caps centered on mountain massifs, and featured phases of ice-sheet expansion and contraction. These ice masses were most likely cold-based over uplands and warm-based across lowlands and near their margins. For 20 million years ice sheets fluctuated on Croll-Milankovitch frequencies. At ~14 Ma the ice sheet expanded to its maximum and deepened a preexisting radial array of troughs selectively through the coastal mountains and eroded the continental

  11. Surface atmosphere exchange in dry and a wet regime over the Ganges valley: a comprehensive investigation with direct observations and numerical simulations

    Science.gov (United States)

    Sathyanadh, Anusha; Prabhakaran, Thara; Karipot, Anandakumar

    2017-04-01

    Land atmosphere interactions in the Ganges Valley basin is a topic of significant importance as it is most vulnerable region due to extreme weather, air pollution, etc. The complete energy balance observations over this region was conducted as part of the CAIPEEX-IGOC (Cloud Aerosol Interaction and Precipitation Enhancement Experiment - Integrated Ground based Observational Campaign) experiment for an entire year. These observations give first insight into the partitioning of energy in this vulnerable environment during the dry and wet regimes, which are typically part of the intraseasonal oscillations during the Indian monsoon season. These transitions wet-dry and dry-wet are poorly represented in GCMs and is the motivation for the detailed investigation here. Observations conducted with micrometeorological tower instrumented with eddy covariance sensors, radiation balance, soil heat flux measurements, microwave radiometer, sodar, radiosonde data are used in the present study. A set of numerical investigations of different Planetary Boundary Layer (PBL) schemes is also carried out to investigate features of the diurnal cycle during the wet and dry regimes. General behaviour of both local and nonlocal PBL schemes found from the investigation is to accomplish enhanced mixing, leading to a deeper PBL in the valley. However, observations give clear evidence of residual boundary layer characterised by a weak stratification, playing a key role in the exchange of PBL air mass with that of free atmosphere. Impact of changes in parameterization and controlling factors on the PBL height are investigated. Case studies for a dry phase during the incidence of a heat wave and a wet phase during a land depression are presented. Observed diurnal features of the surface meteorological parameters including the surface energy budget components were well captured by local and nonlocal PBL schemes during both the cases. Vertical profiles of temperature, mixing ratio and winds from

  12. Geochemical features and sources of hydrocarbons and fatty acids in soils from the McMurdo Dry Valleys in the Antarctic

    Science.gov (United States)

    Matsumoto, Genki I.; Honda, Eisuke; Sonoda, Kazuhiko; Yamamoto, Shuichi; Takemura, Tetsuo

    2010-08-01

    We studied the geochemical features and compound-specific (CS)-δ 13C of hydrocarbons and fatty acids in soil samples from the McMurdo Dry Valleys in the Antarctic to elucidate their source organisms and characteristics of their environments. Total organic carbon contents in soil samples were extremely low reflecting extremely harsh environments for organisms. Normal-alkanes ranging in carbon chain length from n-C 14 to n-C 38 with the predominance of odd-carbon numbers were found, together with n-alkenes ( n-C 23:1 to n-C 27:1). Normal-alkanoic acids ranging in carbon chain length from n-C 10 to n-C 30 with the predominance of even-carbon numbers were detected in the samples, along with small amounts of branched ( iso and anteiso) and n-alkenoic acids. CS-δ 13C values of long-chain n-alkanes ( n-C 20 to n-C 29) ranged from -30.4 to -26.6‰. CS-δ 13C values of n-alkanoic acids with short-chain carbon numbers ( n-C 14 to n-C 19) ranging from -27.7 to -21.7‰ were much higher than those of long-chain carbon numbers ( n-C 20 to n-C 30, -32.5 to -25.3‰). The geochemical features and CS-δ 13C values of long-chain n-alkanes and n-alkanoic acids revealed that they are originated from lichen and/or vascular plant debris from the pre- and inter-glacial periods in this region, whereas short-chain n-alkanoic acids are come from microalgae and cyanobacterial debris. CS-δ 13C values suggest that they are derived from gymnosperms and/or C 4 plants in the cold and dry environments of the pre- and inter-glacial periods of the McMurdo Dry Valleys region.

  13. Effects of climatic conditions on radial growth and sap-flow along an elevation gradient in an inner-alpine dry valley

    Science.gov (United States)

    Obojes, Nikolaus; Newesely, Christian; Bertoldi, Giacomo; Tassser, Erich; Oberhuber, Walter; Mayr, Stefan; Tappeiner, Ulrike

    2016-04-01

    Water availability in mountain forests might change in the future due to rising temperatures and changing precipitation patterns, affecting tree water relations and growth conditions. Changing temperature and precipitation along an elevation gradient in an inner-alpine dry valley in South Tyrol-Italy were used to investigate possible effects of climate change on the transpiration and growth of European Larch (Larix decidua). Stem circumference variation of European Larch was measured for 4 years (2012-2015) with automatic band dendrometers and sap flow for 2 years (2013-2014) with trunk heat balance sensors at 3 sites at elevations of 1115 m, 1715 m, and 1990 m above sea level at a SE-exposed slope. During the first two, rather dry, years, transpiration and stem circumference were reduced during dry periods of one to three weeks at the two lower but not at the highest site. As a consequence, overall yearly radial growth was largest at the highest site in those two years. In 2014, with very high precipitation and colder summer temperatures no correlation of elevation, transpiration, and radial growth was observed. In 2015, with a dry and hot summer, initially high growth rates were strongly reduced after the end of May at the two lower sites. Overall the radial growth of Larix decidua seems to be limited by water scarcity up to an elevation of more than 1700 m a.s.l. in our study area except for unusually wet years. Our 4-year measurements were confirmed by dendro-climatic analysis of stem cores taken at five sites (the three original ones plus two additional sites at 1070 and at the forest line at 2250m) covering the last 50 to 150 years. Year ring widths were lower and highly correlated to precipitation at the lowest sites, and overall highest at the 1990 m site. Our results show that the growth of Larix decidua, which is often considered as more drought resistant than e.g. Picea abies, is limited by water availability at dry conditions in the Alps which might

  14. LEAF AND INFLORESCENCE PRODUCTION OF THE WINE PALM (Attalea butyracea IN THE DRY MAGDALENA RIVER VALLEY, COLOMBIA

    Directory of Open Access Journals (Sweden)

    Olivares Ingrid

    2013-07-01

    Full Text Available The leaves of the wine palm (Attalea butyracea are collected and harvested along theMagdalena River Valley in Colombia. Young leaves are used as a ceremonial symbol onPalm Sunday, and expanded leaves are used for thatching and for making handicrafts.In order to document leaf production and to evaluate the effect of leaf extraction ongrowth and development, we marked 80 individuals under extractive conditions and40 individuals under non-extractive conditions and we followed leaf production duringseven months. We also studied inflorescence production for one year to evaluate thepotential of A. butyracea as a source of sap for sugar manufacture. Leaf productionin juveniles and sub-adults was correlated to the number of expanded leaves. Leafproduction in adults was correlated with the number of expanded leaves and withstem size. Palms flower throughout the year, and several inflorescences developsimultaneously. The flowering peak occurs during the drier season. Inflorescenceproduction was correlated to the stem height and to the number of expanded leaves,and it is probably affected by leaf harvest. We recommend leaf extraction only fromindividuals with stem over 3 m and with more than 25 expanded leaves. Inflorescenceproduction of A. butyracea gives the palm a potential for sap extraction.

  15. 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

  16. 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.

  17. Growth-climate relations of Larix decidua and Pinus cembra in an inner-alpine dry valley

    Science.gov (United States)

    Obojes, Nikolaus; Meurer, Armin; Tasser, Erich; Mayr, Stefan; Oberhuber, Walter; Tappeiner, Ulrike

    2016-04-01

    Due to climate change, increasing temperatures and decreasing precipitation are expected for the southern part of the Alps. To estimate possible effects on growth conditions in mountain forests we investigated climate to tree growth relations along an elevation gradient in one of the driest regions in the Alps, the LTSER site Matsch/Mazia in South Tyrol, Italy. Besides Picea abies (27%), Larix decidua (42%) and Pinus cembra (25%) are the two most abundant tree species in the study area. While Pinus cembra is restricted to the sub-alpine zone, Larix decidua is ranging from the lowest parts of the study area up to the tree line, especially at lower elevations also due to reforestation efforts of heavily eroding pastures in the past 120 years and traditional silvopastural systems which promote Larch. The reaction of the two species to changing climatic conditions during the last 150 years were analyzed by relating tree ring width of Larix decidua from 8 sites at elevations from 1070 to 2430 m a.s.l. and of Pinus cembra from 5 sites ranging from 2030 to 2430 m a.s.l. at SE- and NW-exposed slopes to temperature and precipitation records from the nearby station at Marienberg (1310 m a.s.l.) dating back to 1860. Overall, basal area increment was highest at sites at about 2000 m a.s.l and decreased at higher and for Larch at lower sites. At lower elevations up to 1750 m a.s.l. growth rates of Larix decidua generally decreased during the last 15 years, especially during and after the 2003 heat wave, after increasing from the 1950s to the 1980s . On the contrary, at elevations of more than 2000 m a.s.l., growth of both Larch and Pinus cembra increased since the 1990s. Growth-climate correlations and extreme year analysis show a similar results: at low-elevation sites, growth was correlated positively to precipitation and reacted positively to wet and cold years and negatively to hot and dry years. On the other hand, growth was positively correlated to temperature at the

  18. Testing the Snowpack Hypothesis for Gully Formation on Mars: Utilization of the Antarctic Dry Valleys (ADV) as a Terrestrial Analog

    Science.gov (United States)

    Morgan, G. A.

    2007-12-01

    The identification of young gullies on Mars suggests that liquid water has flowed across the martian surface during the recent climatic regime which has otherwise been considered to have been cold and dry. Research into the martian gullies suggest that water flow was concurrent with periods of higher obliquity, yet, no consensus has been reached regarding whether the water which eroded the gullies originated within internal confined aquifers or was sourced from surface/near-surface snow and ice deposits. We undertook research into gully formation in the ADV, a hyper-arid very cold polar desert which is considered the closest terrestrial analog to current Martian conditions. Our research identified two water sources: 1) perennial snow/ice deposits within the gully alcoves. 2). Annual accumulations of windblown snow trapped within the channels themselves. The melt produced by each source was found to be a function of: the local microclimatic zone, lithology, slopes and elevation. We also classified and mapped a range of meso-scale features (m to 10s of m scale) that can be compared to landforms identifiable within HiRISE images in order to further constrain gully formation processes and potential levels of recent activity on Mars. The exchange of salts between the runoff within the gullies and the surrounding ADV soils may also provide further insights into the generation of brines within polar deserts; this has important ramification regarding their development on Mars and the extent to which the freezing point can be depressed. Our findings demonstrate how gully erosion can take place in the absence of aquifer-fed sapping and within a region of low precipitation and thus provides further support for a surface source of water for the martian gullies. These results also underline the significance of snowmelt as a source of water for both ADV hydrological systems and ecosystems.

  19. Pressurized brines in continental Antarctica as a possible analogue of Mars

    Science.gov (United States)

    Forte, Emanuele; Dalle Fratte, Michele; Azzaro, Maurizio; Guglielmin, Mauro

    2016-09-01

    Interest in brines in extreme and cold environments has recently increased after they have been found on Mars. Those brines can be potential new subsurface habitats for peculiar ecosystems. In the McMurdo Dry Valleys of the Antarctic, the best analogue for Mars conditions, only a few cases of brines have been identified in some perennially frozen lakes and in one case in an underground aquifer. Here, we present the occurrence of pressurized brines in a shallow perennially ice-covered lake south of 70°S in an ice-free area of Victoria Land, Antarctica. For the first time, we also imaged, by means of ground penetrating radar data, the existence of a pingo-like-feature (PLF) formed by the extrusion of brines, which has also been confirmed by borehole evidence. Those brines are fed by an underground talik external to the lake basin, enhancing the possibility of unexploited ecosystems that could find an analogue in Martian environments.

  20. Mineral resources of Antarctica

    Science.gov (United States)

    Compiled and edited by Wright, Nancy A.; Williams, Paul L.

    1974-01-01

    Although the existence of mineral deposits in Antarctica is highly probable, the chances of finding them are quite small. Minerals have been found there in great variety but only as occurrences. Manganese nodules, water (as ice), geothermal energy, coal, petroleum, and natural gas are potential resources that could perhaps be exploited in the future. On the basis of known mineral occurrences in Antarctica and relationships between geologic provinces of Antarctica and those of neighboring Gondwana continents, the best discovery probability for a base-metal deposit in any part of Antarctica is in the Andean orogen; it is estimated to be 0.075 (75 chances in 1,000).

  1. Microbial Energetics Beneath the Taylor Glacier, Antarctica

    Science.gov (United States)

    Mikucki, J. A.; Turchyn, A. V.; Farquhar, J.; Priscu, J. C.; Schrag, D. P.; Pearson, A.

    2007-12-01

    Subglacial microbiology is controlled by glacier hydrology, bedrock lithology, and the preglacial ecosystem. These factors can all affect metabolic function by influencing electron acceptor and donor availability in the subglacial setting leaving biogeochemical signatures that can be used to determine ecosystem processes. Blood Falls, an iron-rich, episodic subglacial outflow from the Taylor Glacier in the McMurdo Dry Valleys Antarctica provides an example of how microbial community structure and function can provide insight into subglacial hydrology. This subglacial outflow contains cryoconcentrated, Pliocene-age seawater salts that pooled in the upper Taylor Valley and was subsequently covered by the advance of the Taylor Glacier. Biogeochemical measurements, culture-based techniques, and genomic analysis were used to characterize microbes and chemistry associated with the subglacial outflow. The isotopic composition of important geochemical substrates (i.e., δ34Ssulfate, Δ33Ssulfate, δ18Osulfate, δ18Owater, Δ14SDIC) were also measured to provide more detail on subglacial microbial energetics. Typically, subglacial systems, when driven to anoxia by the hydrolysis of organic matter, will follow a continuum of redox chemistries utilizing electron acceptors with decreasing reduction potential (e.g., Fe (III), sulfate, CO2). Our data provide no evidence for sulfate reduction below the Taylor Glacier despite high dissolved organic carbon (450 μM C) and measurable metabolic activity. We contend that, in the case of the Taylor Glacier, the in situ bioenergetic reduction potential has been 'short-circuited' at Fe(III)-reduction and excludes sulfate reduction and methanogenesis. Given the length of time that this marine system has been isolated from phototrophic production (~2 Mya) the ability to degrade and consume increasingly recalcitrant organic carbon is likely an important component to the observed redox chemistry. Our work indicates that glacier hydrology

  2. [Vegetation biomass allocation and its spatial distribution after 20 years ecological restoration in a dry-hot valley in Yuanmou, Yunnan Province of Southwest China].

    Science.gov (United States)

    Li, Bin; Tang, Guo-Yong; Li, Kun; Gao, Cheng-Jie; Liu, Fang-Yan; Wang, Xiao-Fei

    2013-06-01

    By using layering harvest method, a comparative study was conducted on the biomass allocation and its spatial distribution of 20-year-old Eucalyptus camaldulensis plantation, Leucaena leucocephala plantation, and E. camaldulensis-L. leucocephala plantation in Yuanmou dry-hot valley of Yunnan Province, Southwest China. The stand biomass in the mixed E. camaldulensis-L. leucocephala plantation (82.99 t x hm(-2)) was between that of monoculture E. camaldulensis plantation (60.64 t x hm(-2)) and L. leucocephala plantation (127.79 t x hm(-2)). The individual tree biomass of E. camaldulensis in the mixed plantation (44.32 kg) was 49.8% higher than that in monoculture plantation (29.58 kg). The branch and leaf biomass of L. leucocephala (25.4%) in monoculture plantation was larger than that of E. camaldulensis (8.9%) in monoculture plantation, and the aboveground biomass distribution ratio (78.0%) of L. leucocephala (25.4%) was also higher than that of E. camaldulensis (73.4%). The roots of L. leucocephala in both monoculture and mixed plantations were mainly distributed in 0-40 cm soil layer, while those of E. camaldulensis in monoculture and mixed plantations were mainly found in 0-80 cm and 0-60 cm, respectively. The proportion of biomass allocated to roots including medium roots, small roots, and fine roots of L. leucocephala in mixed plantation was higher than that in monoculture plantation, but it was contrary for E. camaldulensis. It was suggested that introducing L. leucocephala in E. camaldulensis plantation promoted the growth of E. camaldulensis, especially for its aboveground biomass, and increased the amount of lateral roots in 0-20 cm soil layer, which had significance in soil and water conservation in the study area.

  3. Distribution of metals in various particle-size fractions in topsoils of a small dry valley system (European Russia, forest zone)

    Science.gov (United States)

    Samonova, Olga; Aseyeva, Elena

    2017-04-01

    A detailed study of heavy metals distribution in various soil grain-size fractions helps to increase the knowledge about the complex nature of metals' occurrence and their distribution pathways in the environment. On the basis of particle size fractionation of topsoil horizons we examined the specific behavior of heavy metals in a small erosional landform located in the humid temperate zone of the Russian Plain. The object of the study is a 400 m small U-shaped dry valley (balka in Russian) with a catchment area of 32.8 ha located in the central part of the Protva river basin, 100 km southwest of Moscow. The uppermost parts of the landform are incised in Late Pleistocene loessial loams, which cover significant portions of interfluve area in the region, while the middle and the lower parts cut through Middle Pleistocene glacial sediments. A total of 50 samples were collected from topsoil horizons of different landform geomorphic units along three cross-sections as well as along the bottom of the landform and its detrital fan. Samples were analyzed for Mn, Cu, Ni, Co, Cr, Zn, Pb, Ti, Zr, and Fe content. Eleven samples were chosen for physical fractionation into 5 grain-size fractions (1-0.25 mm, 0.25-0.05 mm, 0.05-0.01 mm, 0.01-0.001 mm and units, the coarser (sand) fractions showed distinct spatial patterns in the elements' distribution, possibly related to migration processes, the depletion of metals in the landforms' slopes and their prevalent enrichment in the bottom unit is observed.

  4. Bringing Antarctica Home

    Science.gov (United States)

    Constible, Juanita; Williams, Lauren; Faure, Jaime; Lee, Richard E., Jr.

    2012-01-01

    When one thinks of the amazing creatures of Antarctica, an insect probably does not come to mind. But this unlikely animal, and a scientific expedition to Antarctica, was the foundation for a learning event that created a community of learners spanning kindergarten through sixth grade and extended beyond the classroom. Miami University's Antarctic…

  5. Dynamics and mass balance of Taylor Glacier, Antarctica: 1. Geometry and surface velocities

    Science.gov (United States)

    Kavanaugh, J. L.; Cuffey, K. M.; Morse, D. L.; Conway, H.; Rignot, E.

    2009-11-01

    Taylor Glacier, Antarctica, exemplifies a little-studied type of outlet glacier, one that flows slowly through a region of rugged topography and dry climate. This glacier, in addition, connects the East Antarctic Ice Sheet with the McMurdo Dry Valleys, a region much studied for geomorphology, paleoclimate, and ecology. Here we report extensive new measurements of surface velocities, ice thicknesses, and surface elevations, acquired with InSAR, GPS, and GPR. The latter two were used to construct elevation models of the glacier's surface and bed. Ice velocities in 2002-2004 closely matched those in 2000 and the mid-1970s, indicating negligible interannual variations of flow. Comparing velocities with bed elevations shows that, along much of the glacier, flow concentrates in a narrow axis of relatively fast flowing ice that overlies a bedrock trough. The flow of the glacier over major undulations in its bed can be regarded as a “cascade” it speeds up over bedrock highs and through valley narrows and slows down over deep basins and in wide spots. This pattern is an expected consequence of mass conservation for a glacier near steady state. Neither theory nor data from this Taylor Glacier study support the alternative view, recently proposed, that an outlet glacier of this type trickles slowly over bedrock highs and flows fastest over deep basins.

  6. 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

  7. Antarctica - Ross Ice Shelf

    Science.gov (United States)

    1990-01-01

    This color picture of Antarctica is one part of a mosaic of pictures covering the entire polar continent taken during the hours following Galileo's historic first encounter with its home planet. The view shows the Ross Ice Shelf to the right and its border with the sea. An occasional mountain can be seen poking through the ice near the McMurdo Station. It is late spring in Antarctica, so the sun never sets on the frigid, icy continent. This picture was taken about 6:20 p.m. PST on December 8, 1990. From top to bottom, the frame looks across about half of Antarctica.

  8. Coastal-change and glaciological map of the Ross Island area, Antarctica

    Science.gov (United States)

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

    2010-01-01

    Reduction in the area and volume of Earth?s two polar ice sheets is intricately linked to changes in global climate and to the resulting rise in sea level. Measurement of changes in area and mass balance of the Antarctic ice sheet was given a very high priority in recommendations by the Polar Research Board of the National Research Council. On the basis of these recommendations, the U.S. Geological Survey used its archive of satellite images to document changes in the cryospheric coastline of Antarctica and analyze the glaciological features of the coastal regions. The Ross Island area map is bounded by long 141? E. and 175? E. and by lat 76? S. and 81? S. The map covers the part of southern Victoria Land that includes the northwestern Ross Ice Shelf, the McMurdo Ice Shelf, part of the polar plateau and Transantarctic Mountains, the McMurdo Dry Valleys, northernmost Shackleton Coast, Hillary Coast, the southern part of Scott Coast, and Ross Island. Little noticeable change has occurred in the ice fronts on the map, so the focus is on glaciological features. In the western part of the map area, the polar plateau of East Antarctica, once thought to be a featureless region, has subtle wavelike surface forms (megadunes) and flow traces of glaciers that originate far inland and extend to the coast or into the Ross Ice Shelf. There are numerous outlet glaciers. Glaciers drain into the McMurdo Dry Valleys, through the Transantarctic Mountains into the Ross Sea, or into the Ross Ice Shelf. Byrd Glacier is the largest. West of the Transantarctic Mountains are areas of blue ice, readily identifiable on Landsat images, that have been determined to be prime areas for finding meteorites. Three subglacial lakes have been identified in the map area. Because McMurdo Station, the main U.S. scientific research station in Antarctica, is located on Ross Island in the map area, many of these and other features in the area have been studied extensively. The paper version of this map is

  9. Lake Vanda: A sentinel for climate change in the McMurdo Sound Region of Antarctica

    Science.gov (United States)

    Castendyk, Devin N.; Obryk, Maciej K.; Leidman, Sasha Z.; Gooseff, Michael; Hawes, Ian

    2016-09-01

    Lake Vanda is a perennially ice-covered, meromictic, endorheic lake located in the McMurdo Dry Valleys of Antarctica, and an exceptional sentinel of climate change within the region. Lake levels rose 15 m over the past 68 years in response to climate-driven variability in ice-cover sublimation, meltwater production, and annual discharge of the Onyx River, the main source of water to the lake. Evidence from a new bathymetric map and water balance model combined with annual growth laminations in benthic mats suggest that the most recent filling trend began abruptly 80 years ago, in the early 1930s. This change increased lake volume by > 50%, triggered the formation of a new, upper, thermohaline convection cell, and cooled the lower convection cell by at least 2 °C and the bottom-most waters by at > 4 °C. Additionally, the depth of the deep chlorophyll a maximum rose by > 2 m, and deep-growing benthic algal mats declined while shallow benthic mats colonized freshly inundated areas. We attribute changes in hydrology to regional variations in air flow related to the strength and position of the Amundsen Sea Low (ASL) pressure system which have increased the frequency of down-valley, föhn winds associated with surface air temperature warming in the McMurdo Dry Valleys. The ASL has also been implicated in the recent warming of the Antarctic Peninsula, and provides a common link for climate-related change on opposite sides of the continent. If this trend persists, Lake Vanda should continue to rise and cool over the next 200 years until a new equilibrium lake level is achieved. Most likely, future lake rise will lead to isothermal conditions not conducive to thermohaline convection, resulting in a drastically different physical, biogeochemical, and biological structure than observed today.

  10. 金沙江干热河谷区优质晚熟芒果栽培技术%Cultivation Techniques of High Quality Late Mango in Dry and Hot Valley Areas of Jinsha River

    Institute of Scientific and Technical Information of China (English)

    马学林; 郭学红

    2013-01-01

    根据华坪晚熟芒果生长特性,结合金沙江干热河谷区自然气候特点,借鉴10多年的生产经验,集成金沙江干热河谷区优质晚熟芒果规范化栽培技术,包括品种选择、培育初生壮苗、果园规划、定植、嫁接改良、幼树管理、花期管理、幼果期管理、果实膨大期管理、果实成熟期管理、采果后的管理等方面内容,以供参考。%According to the growth characteristics of Huaping late ripening mango ,combined with the natural climate characteristic of dry and hot valley areas of Jinsha River ,based on 10 years of production experiences ,the cultivation technologies of high-quality late mango in dry and hot valley areas of Jinsha River were integrated ,which contained variety choice ,nuture nascent seedlings ,orchard planning ,field planting ,engrafting and improving,young trees management,blooming period management,young fruit stage management,fruit expanding process management,fruit maturation period management ,management after mining furit and so on ,in order to provide references.

  11. Study on dry-hot tolerance of Rhizobium of Acacia confusa isolated from dry-hot valley%干热河谷台湾相思树种根瘤菌的耐干热研究

    Institute of Scientific and Technical Information of China (English)

    沙桦欣; 伍建榕; 周利平; 王芳; 张东华; 马焕成

    2013-01-01

    Through studying the high temperature and drought resistance of Rhizobium sp.of Acacia confuse in the dry-hot valley,the Rhizobium's growth rhythm under the condition of high temperature was revealed in order to provide a theoretical basis for screening out excellent Rhizobium germplasm resources.Through field investigation,the Rhizobium sp.of A.confuse were collected from dryhot valley area,then were separated and purified.The cultivation of symbiotic tumor of the purified Rhizobium stains of A.confuse and aseptic seedlings of A.confuse was conducted,some new Rhizobium stains were selected and vaccinated to YMA culture medium,then cultured with constant temperature under different temperature gradients and the colony numbers and vertical and horizontal diameters were recorded.Through artificially simulating drought conditions,the Rhizobium stains were inoculated and cultured in the PEG culture fluid with concentration gradient of 0,5%,10%,20%,30%,the OD600 values of the bacterial suspension was determined by using spectrophotometer and the corresponding curve figure was drawn out.The experimental results show that the high temperature can significantly inhibit the growth of Rhizobium colonies; the OD values of YMA-PEG solution decreased with the increase of concentration; M-08,M-10,M-11 strains are the swains type that strongly adapted to high temperature and drought; CK,M-05,M-06,M-07,M-09,M-12,M-15 moderately adapted to high temperatures and drought; M-01,M-02,M-03,M-04,M-13 and M-14 strains had weaker adaptability to high temperatures and drought.%通过对干热河谷地区台湾相思树种根瘤菌进行高温干旱等抗性研究,揭示干热河谷地区台湾相思树种根瘤菌在高温条件下生长规律,为发掘优良的根瘤菌种质资源提供理论依据.通过野外调查、采集、分离纯化采自干热河谷地区台湾相思树种的根瘤菌;经与相思树种无菌苗共生接瘤培养,将筛选出的各根瘤菌菌株接种

  12. Living and Working in Antarctica.

    Science.gov (United States)

    Kemp, Noel

    This source book, designed for 11- to 14-year-old students, seeks to describe what life is like in Antarctica. In spite of extreme weather conditions, people go to Antarctica to work every summer. Some of them stay there during the winter as well. This book seeks to supply answers to such questions as: How do people get to Antarctica? Why do they…

  13. Ecosystem Dynamics of the Microbial Mats in Lake Fryxell, Antarctica

    Science.gov (United States)

    Krusor, M.; Mackey, T. J.; Hawes, I.; Jungblut, A. D.; Eisen, J.; Sumner, D. Y.

    2016-12-01

    Microbial communities drive biogeochemical cycles on Earth at micron scales, at which microbial ecosystem networks are highly interconnected to each other and their local environment through trophic interactions and the availability of electron acceptors. Feedbacks among microorganisms and environmental conditions structure microbial communities and micron-scale geochemical gradients. We are exploring interactions among microbial community structure and local geochemistry in Lake Fryxell, a perennially ice-covered, meromictic lake in the McMurdo Dry Valleys, Antarctica. In Lake Fryxell, O2 concentration and photosynthetically active radiation (PAR) decline with depth and influence layered benthic mats, which consist of microorganisms from all three domains. These layered mats change pigmentation and morphology with depth in the lake. In 2012, samples were collected for 16S rRNA and metagenomic sequencing in collaboration with the McMurdo Dry Valleys Long Term Ecological Research program. Samples were collected at 9.0, 9.35, and 9.8 m depth with temperature, pressure, O2 concentration, conductivity, PAR, irradiance, and morphology. O2 microelectrode profiles were also collected. At 9.0 and 9.35 m depths, PAR was relatively high, and the water was supersaturated with O2. At 9.8 m depth, PAR was low and lake water was anoxic, but 50 µmol L-1 of O2 was produced by cyanobacteria, creating a mm-thick zone with free O2 in the mat under anoxic water. As in many microbial mats, community-O2 correlations are present in Lake Fryxell: diversity increases with increasing depth into the mat at all lake depths, and diversity decreases with increasing depth in the lake. Microbial communities are less diverse and the dominant phototrophs change at lower PAR and O2 concentrations. Further, O2 generated by cyanobacteria creates a habitat for aerobic and microaerophilic heterotrophs under an anoxic water column. Some lineages, particularly alpha- and gammaproteobacteria and the

  14. Eddy Flow during Magma Emplacement: The Basemelt Sill, Antarctica

    Science.gov (United States)

    Petford, N.; Mirhadizadeh, S.

    2014-12-01

    The McMurdo Dry Valleys magmatic system, Antarctica, forms part of the Ferrar dolerite Large Igneous Province. Comprising a vertical stack of interconnected sills, the complex provides a world-class example of pervasive lateral magma flow on a continental scale. The lowermost intrusion (Basement Sill) offers detailed sections through the now frozen particle macrostructure of a congested magma slurry1. Image-based numerical modelling where the intrusion geometry defines its own unique finite element mesh allows simulations of the flow regime to be made that incorporate realistic magma particle size and flow geometries obtained directly from field measurements. One testable outcome relates to the origin of rhythmic layering where analytical results imply the sheared suspension intersects the phase space for particle Reynolds and Peclet number flow characteristic of macroscopic structures formation2. Another relates to potentially novel crystal-liquid segregation due to the formation of eddies locally at undulating contacts at the floor and roof of the intrusion. The eddies are transient and mechanical in origin, unrelated to well-known fluid dynamical effects around obstacles where flow is turbulent. Numerical particle tracing reveals that these low Re number eddies can both trap (remove) and eject particles back into the magma at a later time according to their mass density. This trapping mechanism has potential to develop local variations in structure (layering) and magma chemistry that may otherwise not occur where the contact between magma and country rock is linear. Simulations indicate that eddy formation is best developed where magma viscosity is in the range 1-102 Pa s. Higher viscosities (> 103 Pa s) tend to dampen the effect implying eddy development is most likely a transient feature. However, it is nice to think that something as simple as a bumpy contact could impart physical and by implication chemical diversity in igneous rocks. 1Marsh, D.B. (2004), A

  15. Valley Fever

    Science.gov (United States)

    Valley Fever is a disease caused by a fungus (or mold) called Coccidioides. The fungi live in the soil ... from person to person. Anyone can get Valley Fever. But it's most common among older adults, especially ...

  16. Radiocarbon analyses along the EDML ice core in Antarctica

    NARCIS (Netherlands)

    van de Wal, R.S.W.; Meijer, H.A.J.; van Rooij, M.; van der Veen, C.

    2007-01-01

    Samples, 17 in total, from the EDML core drilled at Kohnen station Antarctica are analysed for 14CO and 14CO2 with a dry-extraction technique in combination with accelerator mass spectrometry. Results of the in situ produced 14CO fraction show a very low concentration of in situ produced 14CO. Despi

  17. Radiocarbon analyses along the EDML ice core in Antarctica

    NARCIS (Netherlands)

    Van de Wal, R. S. W.; Meijer, H. A. J.; De Rooij, M.; Van der Veen, C.

    2007-01-01

    Samples, 17 in total, from the EDML core drilled at Kohnen station Antarctica are analysed for (CO)-C-14 and (CO2)-C-14 with a dry-extraction technique in combination with accelerator mass spectrometry. Results of the in situ produced (CO)-C-14 fraction show a very low concentration of in situ produ

  18. Evaluating the Age of Buried Ice in Antarctica Using Ashfall Deposits: New Insights from Deposit Morphology, Grain Shape, and LA-ICP-MS Trace-Element Geochemistry

    Science.gov (United States)

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

    2003-12-01

    deposition, then ashes of different ages and geochemical compositions should be found together in individual deposits. An accurate chronology for buried ice in the western Dry Valleys region of Antarctica has implications for research in atmospheric chemistry (Miocene-aged glacier ice may hold pristine samples of ancient atmosphere), geobiology (ancient microbes are preserved in the ice), and planetary geology (buried ice in Antarctica may serve as an analog for buried ice on Mars).

  19. Spatial Heterogeneity of Ice Cover Sediment and Thickness and Its Effects on Photosynthetically Active Radiation and Chlorophyll-a Distribution: Lake Bonney, Antarctica

    Science.gov (United States)

    Obryk, M.; Doran, P. T.; Priscu, J. C.; Morgan-Kiss, R. M.; Siebenaler, A. G.

    2012-12-01

    The perennially ice-covered lakes in the McMurdo Dry Valleys, Antarctica have been extensively studied under the Long Term Ecological Research project. But sampling has been spatially restricted due to the logistical difficulty of penetrating the 3-6 m of ice cover. The ice covers restrict wind-driven turbulence and its associated mixing of water, resulting in a unique thermal stratification and a strong vertical gradient of salinity. The permanent ice covers also shade the underlying water column, which, in turn, controls photosynthesis. Here, we present results of a three-dimensional record of lake processes obtained with an autonomous underwater vehicle (AUV). The AUV was deployed at West Lake Bonney, located in Taylor Valley, Dry Valleys, to further understand biogeochemical and physical properties of the Dry Valley lakes. The AUV was equipped with depth, conductivity, temperature, under water photosynthetically active radiation (PAR), turbidity, chlorophyll-and-DOM fluorescence, pH, and REDOX sensors. Measurements were taken over the course of two years in a 100 x 100 meter spaced horizontal sampling grid (and 0.2 m vertical resolution). In addition, the AUV measured ice thickness and collected 200 images looking up through the ice, which were used to quantify sediment distribution. Comparison with high-resolution satellite QuickBird imagery demonstrates a strong correlation between aerial sediment distribution and ice cover thickness. Our results are the first to show the spatial heterogeneity of lacustrine ecosystems in the McMurdo Dry Valleys, significantly improving our understanding of lake processes. Surface sediment is responsible for localized thinning of ice cover due to absorption of solar radiation, which in turn increases total available PAR in the water column. Higher PAR values are negatively correlated with chlorophyll-a, presenting a paradox; historically, long-term studies of PAR and chlorophyll-a have shown positive trends. We hypothesized

  20. Antarctica: Discovery & Exploration.

    Science.gov (United States)

    Gascoigne, Toss; Collett, Peter

    An examination of Antarctica, from the first sightings to the heroic explorations of the late 18th and early 19th centuries to modern-day research, is presented in this book. Twelve chapters are as follows: (1) The search begins; (2) Whalers and sealers: bites and nibbles; (3) The new continent: first sight; (4) Wintering: the first party; (5)…

  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. Sustaining dry surfaces under water

    Science.gov (United States)

    Jones, Paul R.; Hao, Xiuqing; Cruz-Chu, Eduardo R.; Rykaczewski, Konrad; Nandy, Krishanu; Schutzius, Thomas M.; Varanasi, Kripa K.; Megaridis, Constantine M.; Walther, Jens H.; Koumoutsakos, Petros; Espinosa, Horacio D.; Patankar, Neelesh A.

    2015-08-01

    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 predictions are consistent with molecular dynamics simulations and experiments.

  3. Tectonics of Antarctica

    Science.gov (United States)

    Hamilton, W.

    1967-01-01

    Antarctica consists of large and wholly continental east Antarctica and smaller west Antarctica which would form large and small islands, even after isostatic rebound, if its ice cap were melted. Most of east Antarctica is a Precambrian Shield, in much of which charnockites are characteristic. The high Transantarctic Mountains, along the Ross and Weddell Seas, largely follow a geosyncline of Upper Precambrian sedimentary rocks that were deformed, metamorphosed and intruded by granitic rocks during Late Cambrian or Early Ordovician time. The rocks of the orogen were peneplained, then covered by thin and mostly continental Devonian-Jurassic sediments, which were intruded by Jurassic diabase sheets and overlain by plateau-forming tholeiites. Late Cenozoic doming and block-faulting have raised the present high mountains. Northeastern Victoria Land, the end of the Transantarctic Mountains south of New Zealand, preserves part of a Middle Paleozoic orogen. Clastic strata laid unconformably upon the Lower Paleozoic plutonic complex were metamorphosed at low grade, highly deformed and intruded by Late Devonian or Early Carboniferous granodiorites. The overlying Triassic continental sedimentary rocks have been broadly folded and normal-faulted. Interior west Antarctica is composed of miogeosynclinal clastic and subordinate carbonate rocks which span the Paleozoic Era and which were deformed, metamorphosed at generally low grade, and intruded by granitic rocks during Early Mesozoic time and possibly during other times also. Patterns of orogenic belts, if systematic, cannot yet be defined; but fragmentation and rotation of crustal blocks by oroclinal folding and strike-slip faulting can be suggested. The Ellsworth Mountains, for example, consist of Cambrian-Permian metasedimentary rocks that strike northward toward the noncorrelative and latitudinally striking Mesozoic terrane of the Antarctic Peninsula in one direction and southward toward that of the Lower Paleozoic: terrane

  4. Erosion-driven uplift in the Gamburtsev Subglacial Mountains of East Antarctica.

    OpenAIRE

    Paxman, G. J. G.; Watts, A. B.; Ferraccioli, F.; Jordan, T.A.; R. E. Bell; Jamieson, S.S.R.; Finn, C A

    1999-01-01

    The relative roles of climate and tectonics in mountain building have been widely debated. Central to this debate is the process of flexural uplift in response to valley incision. Here we quantify this process in the Gamburtsev Subglacial Mountains, a paradoxical tectonic feature in cratonic East Antarctica. Previous studies indicate that rifting and strike-slip tectonics may have provided a key trigger for the initial uplift of the Gamburtsevs, but the contribution of more recent valley inci...

  5. Antarctotrechus balli sp. n. (Carabidae, Trechini: the first ground beetle from Antarctica

    Directory of Open Access Journals (Sweden)

    Allan C. Ashworth

    2016-11-01

    Full Text Available Fossil elytra of a small trechine carabid are reported from the Oliver Bluffs on the Beardmore Glacier at lat. 85°S. They were compared with counterparts from the extant genera Trechisibus, Tasmanorites, Oxytrechus and Pseudocnides. The fossils share some characters but are sufficiently different to be described as a new genus and species. We named the new species Antarctotrechus balli in honour of George E. Ball who made major contributions to the study of carabids through his own research and the training of students while at the University of Alberta, Edmonton, Alberta, Canada. The closest extant relatives to the extinct A. balli are species of Trechisibus, which inhabit South America, the Falkland Islands and South Georgia, and Tasmanorites, which inhabit Tasmania, Australia. Plant fossils associated with A. balli included Nothofagus (southern beech, Ranunculus (buttercup, moss mats and cushion plants that were part of a tundra biome. Collectively, the stratigraphic relationships and the growth characteristics of the fossil plants indicate that A. balli inhabited the sparsely-vegetated banks of a stream that was part of an outwash plain at the head of a fjord in the Transantarctic Mountains. Other insects represented by fossils in the tundra biome include a listroderine weevil and a cyclorrhaphan fly. The age of the fossils, based on comparison of associated pollen with 40Ar/39Ar dated pollen assemblages from the McMurdo Dry Valleys, is probably Early to Mid-Miocene in the range 14–20 Ma. The tundra biome, including A. balli, became extinct in the interior of Antarctica about 14 Ma and on the margins of the continent by 10–13 Ma. A. balli confirms that trechines were once widely distributed in Gondwana. For A. balli and other elements of the tundra biome it appears they continued to inhabit a warmer Antarctica for many millions of years after rifting of Tasmania (45 Ma and southern South America (31 Ma.

  6. Informal STEM Education in Antarctica

    Science.gov (United States)

    Chell, K.

    2010-12-01

    Tourism in Antarctica has increased dramatically with tens of thousands of tourists visiting the White Continent each year. Tourism cruises to Antarctica offer a unique educational experience for lay people through informal science-technology-engineering-mathematics (STEM) education. Passengers attend numerous scientific lectures that cover topics such as the geology of Antarctica, plate tectonics, glaciology, and climate change. Furthermore, tourists experience the geology and glaciology first hand during shore excursions. Currently, the grand challenges facing our global society are closely connected to the Earth sciences. Issues such as energy, climate change, water security, and natural hazards, are consistently on the legislative docket of policymakers around the world. However, the majority of the world’s population is uninformed about the role Earth sciences play in their everyday lives. Tourism in Antarctica provides opportunities for informal STEM learning and, as a result, tourists leave with a better understanding and greater appreciation for both Antarctica and Earth sciences.

  7. DMS pulse and COS valley: the effect of simulated rainfall on sulfur gas exchange in dry soils of uncultivated marine terraces

    Science.gov (United States)

    Whelan, M.; Khan, M. H.; Barnash, K.; Vollering, J.; Rhew, R.

    2011-12-01

    Atmospheric sulfur compounds regulate climate by affecting cloud dynamics and reducing the amount of solar radiation that reaches the Earth's surface. Quantifying the terrestrial-atmosphere exchanges of sulfur has been challenging as only some of the controlling factors are known. In general, oxic soils are observed to act as a sink of reduced sulfur compounds (RSCs), while anoxic soils tend to act a source. Changes in soil moisture are therefore expected to greatly influence the direction of net gas fluxes of RSCs. Here we report the effect of simulated rainfall on soil samples from uncultivated marine terraces near Santa Cruz, CA, U.S.A (37.0°N, 122°W). Soils were collected in the dry season of a Mediterranean-type climate and air dried before the analysis. The rate of production of dimethyl sulfide (DMS), a compound known to be produced by phytoplankton and bacteria, increased dramatically in the first hours after water addition, tapering off over a few days. A concurrent pulse in microbial respiration (as CO_2) was observed. Soils that experience lengthy dry periods, such as those from arid and Mediterranean climates, have been shown to exhibit increases of carbon mineralization after rain events due to a combination of released soil organic matter and increased microbial activity. Conversely, production of carbonyl sulfide (COS), the most abundant reduced sulfur compound in the atmosphere, decreased immediately upon wetting the soil, perhaps due to isolation of the soil atmosphere from the headspace by water. These simultaneous processes after the addition of water can transform a soil in the bulk oxic state into a net source of RSCs in a relatively short span of time.

  8. Effect of dry land transformation and quality of water use for crop irrigation on the soil bacterial community in the Mezquital Valley, Mexico

    Science.gov (United States)

    Lüneberg, Kathia; Schneider, Dominik; Daniel, Rolf; Siebe, Christina

    2017-04-01

    Soil bacteria are important determinants of soil fertility and ecosystem services as they participate in all biogeochemical cycles. Until now the comprehension of compositional and functional response that bacterial communities have to land use change and management, specifically in dry land its limited. Dry lands cover 40% of the world's land surface and its crop production supports one third of the global population. In this regions soil moisture is limited constraining farming to the rainy season or oblige to irrigate, as fresh water resources become scarce, to maintain productivity, treated or untreated wastewater for field irrigation is used. In this study the transformation of semiarid shrubland to agriculture under different land systems regarding quantity and quality of water use for crop irrigation on bacterial communities was investigated. The land systems included maize rain-fed plantations and irrigation systems with freshwater, untreated wastewater stored in a dam and untreated wastewater during dry and rainy season. Bacterial community structure and function was heavily affected by land use system and soil properties, whereas seasonality had a slighter effect. A soil moisture, nutrient and contaminant-content increasing gradient among the land use systems, going from rain fed plantation over fresh water, dam wastewater to untreated wastewater irrigated plantations was detected, this gradient diminished the abundance of Actinobacteria and Cyanobacteria, but enhanced the one from Bacteroidetes and Proteobacteria. Discernible clustering of the dry land soil communities coincides with the moisture, nutrient and contaminant gradient, being shrubland soil communities closer to the rain-fed's system and farer to the one from untreated wastewater irrigated soil. Soil moisture together with sodium content and pH were the strongest drivers of the community structure. Seasonality promoted shifts in the composition of soil bacteria under irrigation with

  9. 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

  10. Hovercraft experience in Antarctica

    Science.gov (United States)

    Cook, Harvey C.

    The Model 1500 TD air-cushion vehicle (ACV) has been modified for the extreme conditions encountered in Antarctic operations; these operations began in the 1988-1989 austral summer. Performance evaluations covering 300 hours of engine operations have been obtained which demonstrate the basic soundness of this ACV's design and construction, and its applicability to Antarctic operations, where it was able to reduce travel time and fuel consumption in excess of 40 percent. In addition, passenger comfort was increased manyfold over wheeled and tracked vehicles for comparable missions. The ACV is judged capable of solving many of the transportation problems experienced in Antarctica.

  11. Soil Aggregate Features under Tamarindus indica Forest with Different Plant Compositions in Dry-hot Valley%干热河谷不同酸豆林土壤团聚体特征分析

    Institute of Scientific and Technical Information of China (English)

    彭辉; 周红敏; 徐肇友; 瞿虹; 纪中华

    2014-01-01

    Experiments were conducted on the soil aggregates underTamarindus indica forest with bared land(L+G)CK), with fireweed(L+Z), with Paspalum notatum (L+B), withPhyllanthus emblica (L+Y), and withCajanus cajan (L+M) in dry-hot valley of Yunnan. R0.25(percentage of soil aggregates with diameter larger than 0.25mm), mean weight diameter (MWD), geometric mean diameter (GMD) and fractal dimension (D) were determined at 3 soil layers (0 - 10 cm, >10 - 20 cm, >20 – 40 cm). The results showed that L+B promoted the conservation of soil macro-aggregates, L+Z and L+G could improve the soil aggregate structure, L+Y and L+M forestlands reduced the proportion of macro-aggregates in the soil but increased micro-aggregates content. The experiment demonstrated that in dry-hot valley, conservation tillage was conducive to the sustainable management ofT. indica.%采用干筛法对金沙江干热河谷区酸豆林+光板地(裸地)、酸豆林+杂草、酸豆林+百喜草、酸豆林+余甘子、酸豆林+木豆5种酸豆林地在0~10 cm、>10~20 cm、>20~40 cm的3个土层中的R0.25、MWD、GMD和分形维数D变化进行研究,结果表明:5种酸豆林模式中,酸豆林+百喜草模式有利于土壤大团聚体的保存,酸豆林+杂草模式和酸豆林+光板地模式提升土壤团聚结构,但是效果并不显著,而酸豆林+余甘子模式和酸豆林+木豆模式则降低了土壤中大团聚体的比例,使土壤中的微团聚体含量增加;在干热河谷实施保护性耕作有利于酸豆林的可持续经营。

  12. 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.

  13. 云南干热河谷地区台湾相思树根瘤菌的抗逆性%Stress Resistance of Rhizobia Isolated from Acacia confusa in Hot-dry Valley of Yunnan

    Institute of Scientific and Technical Information of China (English)

    王芳; 沙桦欣; 马焕成; 高瑾; 张东华; 伍建榕

    2014-01-01

    为探明云南干热河谷台湾相思树根瘤菌的抗逆性,筛选优良的根瘤菌菌株,对分离自云南干热河谷台湾相思的32株根瘤菌进行了耐盐、耐高温和耐干旱的抗逆性试验。结果表明:在供试的32株根瘤菌中,对干旱适应性较强的菌株占21.9%,多数菌株对高温具有较强的耐受性,31.25%的菌株可以在45℃的高温下生长,表现出极强的抗热性;有78.13%的菌株可在0.5%的盐浓度下生长,具有一定的耐盐性,其中有31.25%的菌株耐盐浓度可达2%、3%甚至5%。SWF-01、SWF-02、SWF-06和 SWF-19为抗干旱、抗高温和抗盐性能均较强的优良菌株。%In order to explore the stress resistance of rhizobia isolated from A.confusa in hot-dry valley of Yunnan,screen the fine rhizobia strains,32 rhizobia strains isolated from A.confuse grown in hot-dry valley of Yunnan were tested on their tolerance to NaCl,temperature and drought variation.The results indicated that the strains that strongly adapted to drought accounted for 21.9%.Most of the strains were of strong tolerance to high temperature,31.25% strains could grow at high temperature of 45℃.78.13% strains could grow in 1% concentration of NaCl,and 31.25% strains tolerated NaCl stress in 2%,3% and 5% concentration.Four strains of SWF-01,SWF-02,SWF-06 and SWF-19 showed high tolerance to drought,salt and high temperature.

  14. Water dynamics in hyperarid soils of Antarctica including water adsorption and salt hydration

    Science.gov (United States)

    Hagedorn, B.; Sletten, R. S.

    2009-12-01

    Soils in the McMurdo Dry Valleys, Antarctica contain ice and considerable amounts of salt. Ice often occurs at shallow depth throughout the dry valleys and other areas of hyperarid permafrost, notably on Mars. This common occurrence of shallow ice is enigmatic; however, since according to published sublimation models it should disappear relatively quickly (at rates of order 0.1 mm a-1) due to vapor loss to the atmosphere. The disagreement between the occurrence of ice on one hand and process-based vapor transport models on other hand suggests that processes in addition to vapor transport have influence on ice stability. From a number of possible processes, infiltration of snowmelt during summer month and vapor trapping due to overlaying snow cover in winter have been discussed in more detail and both processes are likely to slow down ice sublimation. At this point, however, there are only limited field-observations to confirm the presence of such processes. The present study aims to investigate the effect of water adsorption, salt hydration, and freezing point depression on water transport and ice stability. We hypothesize that hydration of salts and water adsorption on grain surfaces play an important role in the survival of ground ice and as water reservoir in these areas and should be taken into account when modeling vapor transport. Furthermore, there is evidence that salt content in ground ice is high enough to cause formation of brines at subfreezing temperatures that can lead to a growth of ground ice. To support our hypothesis we set up a field experiment by monitoring soil temperature, soil humidity, and soil moisture along with climate data and snow cover. In addition we collected soil samples to measure water potential, salt composition, ice content, and soil texture. Soil samples were extracted with water to measure soluble salt content along dry and ice rich soil profiles. In addition we measured soil moisture retention curves at different vapor

  15. Antarctica Day: An International Celebration

    Science.gov (United States)

    Pope, A.; Hambrook Berkman, J.; Berkman, P. A.

    2013-12-01

    For more than half a century, the 1959 Antarctic Treaty continues to shine as a rare beacon of international cooperation. To celebrate this milestone of peace in our civilization with hope and inspiration for future generations, Antarctica Day is celebrated each year on December 1st , the anniversary of the Antarctic Treaty signing. As an annual event - initiated by the Foundation for the Good Governance of International Spaces (www.internationalspaces.org/) in collaboration with the Association of Polar Early Carer Scientists (www.apecs.is) - Antarctica Day encourages participation from around the world. The Antarctic Treaty set aside 10% of the earth, 'forever to be used exclusively for peaceful purposes in the interest of mankind.' It was the first nuclear arms agreement and the first institution to govern all human activities in an international region beyond sovereign jurisdictions. In this spirit, Antarctica Day aims to: - Demonstrate how diverse nations can work together peacefully, using science as a global language of cooperation for decision making beyond national boundaries, - Provide strategies for students learning about Antarctica through art, science and history at all school levels, - Increase collaboration and communication between classrooms, communities, researchers and government officials around the world, and - Provide a focus for polar educators to build on each year. Through close collaboration with a number of partners. Antarctica Day activities have included: a Polar Film Festival convened by The Explorers Club; live sessions connecting classrooms with scientists in Antarctica thanks to PolarTREC and ARCUS; an international activity that involved children from 13 countries who created over 600 flags which exemplify Antarctica Day (these were actually flown in Antarctica with signed certificates then returned to the classes); a map where Antarctica Day participants all over the world could share what they were doing; an Antarctic bird count

  16. Syn- and post-orogenic alkaline magmatism in a continental arc: Along-strike variations in the composition, source, and timing of igneous activity in the Ross Orogen, Antarctica

    Science.gov (United States)

    Hagen-Peter, G.; Cottle, J. M.

    2013-12-01

    Neoproterozoic-Paleozoic convergence and subduction along the margin of East Gondwana (Australia, New Zealand, Antarctica) resulted in a belt of deformed and metamorphosed sedimentary rocks and batholith-scale igneous intrusions comparable in size to the present day Andes. Mid-crustal levels of this belt, known as the Ross Orogen in Antarctica, are exposed in the basement of the Cenozoic Transantarctic Mountains, providing snapshots of the intrusive magma system of a major continental arc. Whole rock major- and trace-element geochemistry, Hf isotopes in zircon, and U-Pb geochronology have identified along-strike variations in the composition, source, and timing of magmatism along ~200 km of the southern Victoria Land segment of the orogen. There is an apparent younging of the igneous activity from south to north. New U-Pb ages for intrusive rocks from the Koettlitz Glacier Alkaline Province (KGAP) reveal that igneous activity spanned ca. 565-500 Ma (~30 m.y. longer than previously recognized), while immediately to the north in the Dry Valleys area most igneous activity was confined to a relatively short period (ca. 515-495 Ma). Alkaline and subalkaline igneous rocks occur in both the Dry Valleys area and the KGAP, but alkaline rocks in the Dry Valleys are restricted to the latest phase of magmatism. Na-alkaline rocks in the KGAP, including nepheline syenites, carbonatites, and A-type granites, range in age from ca. 545-500 Ma and overlap in age with more typical subduction/collision-related I- and S-type granites elsewhere in southern Victoria Land. Strong enrichments in the LILE and LREE and high LILE/HFSE and LREE/HREE of samples from the KGAP reveal a source enriched in aqueous-mobile elements, potentially a strongly metasomatized mantle wedge beneath the arc. In the Dry Valleys area, rocks with alkali-calcic composition constitute only the youngest intrusions (505-495 Ma), apparently reflecting a shift to post-orogenic magmatism. Zircons from Dry Valleys

  17. Radiometric 81Kr dating identifies 120,000-year-old ice at Taylor Glacier, Antarctica.

    Science.gov (United States)

    Buizert, Christo; Baggenstos, Daniel; Jiang, Wei; Purtschert, Roland; Petrenko, Vasilii V; Lu, Zheng-Tian; Müller, Peter; Kuhl, Tanner; Lee, James; Severinghaus, Jeffrey P; Brook, Edward J

    2014-05-13

    We present successful (81)Kr-Kr radiometric dating of ancient polar ice. Krypton was extracted from the air bubbles in four ∼350-kg polar ice samples from Taylor Glacier in the McMurdo Dry Valleys, Antarctica, and dated using Atom Trap Trace Analysis (ATTA). The (81)Kr radiometric ages agree with independent age estimates obtained from stratigraphic dating techniques with a mean absolute age offset of 6 ± 2.5 ka. Our experimental methods and sampling strategy are validated by (i) (85)Kr and (39)Ar analyses that show the samples to be free of modern air contamination and (ii) air content measurements that show the ice did not experience gas loss. We estimate the error in the (81)Kr ages due to past geomagnetic variability to be below 3 ka. We show that ice from the previous interglacial period (Marine Isotope Stage 5e, 130-115 ka before present) can be found in abundance near the surface of Taylor Glacier. Our study paves the way for reliable radiometric dating of ancient ice in blue ice areas and margin sites where large samples are available, greatly enhancing their scientific value as archives of old ice and meteorites. At present, ATTA (81)Kr analysis requires a 40-80-kg ice sample; as sample requirements continue to decrease, (81)Kr dating of ice cores is a future possibility.

  18. Holocene depositional environments and surface-level changes at Lake Fryxell, Antarctica

    Science.gov (United States)

    Whittaker, T.E.; Hall, B.L.; Hendy, C.H.; Spaulding, S.A.

    2008-01-01

    We report on Holocene surface-level variations of Lake Fryxell, Antarctica, as determined from multi-proxy analyses of 18 sediment cores. During this time accumulating sediments were predominantly aeolian sand with algal and carbonate laminae. Based on stratigraphy, mineralogy and diatom assemblages we suggest some carbonate laminae were deposited when lake level dropped, leading to concentration and subsequent precipitation of salts. Although lake level appears to have remained relatively stable throughout the Holocene, minor (<4.5 m below present) lowstands occurred at approximately 6400, 4700, 3800 and ??? 1600 cal. yr BP. The stability of Lake Fryxell during the Holocene contrasts with large-scale variability at other Dry Valleys lakes (eg, Lake Vanda) and with suggestions from chemical diffusion models of a near-desiccation at ???1200 cal. yr BP. The reason for the comparative stability of Lake Fryxell is uncertain, but may be the result of basin morphology and the number, aspect and proximity of meltwater sources. ?? 2008 SAGE Publications.

  19. Radiometric 81Kr dating identifies 120,000 year old ice at Taylor Glacier, Antarctica

    CERN Document Server

    Buizert, Christo; Jiang, Wei; Purtschert, Roland; Petrenko, Vasilii V; Lu, Zheng-Tian; Mueller, Peter; Kuhl, Tanner; Lee, James; Severinghaus, Jeffrey P; Brook, Edward J

    2014-01-01

    We present the first successful 81Kr-Kr radiometric dating of ancient polar ice. Krypton was extracted from the air bubbles in four ~350 kg polar ice samples from Taylor Glacier in the McMurdo Dry Valleys, Antarctica, and dated using Atom Trap Trace Analysis (ATTA). The 81Kr radiometric ages agree with independent age estimates obtained from stratigraphic dating techniques with a mean absolute age offset of 6 +/- 2.5 ka. Our experimental methods and sampling strategy are validated by 1) 85Kr and 39Ar analyses that show the samples to be free of modern air contamination, and 2) air content measurements that show the ice did not experience gas loss. We estimate the error in the 81Kr ages due to past geomagnetic variability to be below 3 ka. We show that ice from the previous interglacial period (MIS 5e, 130-115 ka before present) can be found in abundance near the surface of Taylor Glacier. Our study paves the way for reliable radiometric dating of ancient ice in blue ice areas and margin sites where large samp...

  20. 基于BIOCLIM模型的元江干热河谷稀树灌木草丛空间分布研究%The Spatial Distribution Research of Savanna Shrub and Grass of Yuanjiang Dry-hot Valleys Based on the BIOCLIM Model

    Institute of Scientific and Technical Information of China (English)

    王一凯; 张蒙蒙; 段卫虎; 杨凯悦; 黄诚; 周汝良

    2015-01-01

    According to the three factors affecting the temperature ,digital elevation model (DEM ) and the normalized difference vegetation index (NDVI) of Savanna shrub and grass of Yuanjiang dry -hot valleys , the article uses the BIOCLIM model to simulate the spatial distribution of Savanna shrub and grass of Yuan‐jiang dry -hot valleys ,w hich realizes the visual expression of spatial distribution of the dry -hot valleys in Yuanjiang County .The results show that the distribution of dry -hot valleys mainly concentrates on both sides outside Yuanjiang County .The dry -hot valleys'distribution is more concentrated in the east area but more dispersed in south area .Moreover ,in recent years ,the increasing human activities have some influences on the ecological environment of Yuanjiang river valley .The model forecasts the future distribution of dry ar‐ea in Yuanjiang County ,w hich aims to provide decision support for biodiversity conservation and vegetation restoration in the area .%根据影响干热河谷稀树灌木草丛分布的温度、数字高程模型(DEM )以及归一化植被指数(NDVI)三个因子,使用BIOCLIM模型模拟元江县干热河谷稀疏灌木草丛空间分布,实现了元江县干热河谷空间分布的可视化表达。结果表明:干热河谷分布主要集中于除元江县城外的河谷两侧,其中东部分布较为集中,而在南部地区分布较为分散。加之近年来人为活动的加剧,对元江河谷生态环境的变化也有一定影响,该模型很好地预测了未来元江县干热面积的分布情况,以期对生物多样性保护和植被恢复提供决策支持。

  1. Characterization of dissolved organic material in the interstitial brine of Lake Vida, Antarctica

    Science.gov (United States)

    Cawley, Kaelin M.; Murray, Alison E.; Doran, Peter T.; Kenig, Fabien; Stubbins, Aron; Chen, Hongmei; Hatcher, Patrick G.; McKnight, Diane M.

    2016-06-01

    Lake Vida (LV) is located in the McMurdo Dry Valleys (Victoria Valley, East Antarctica) and has no inflows, outflows, or connectivity to the atmosphere due to a thick (16 m), turbid ice surface and cold (low salt sub-fractions and allowed comparison to other Antarctic lake DOM samples isolated using similar procedures. Compared to other Antarctic lakes, a lower portion of the DOC was retained by XAD-8 (∼10% vs. 16-24%) resin, while the portions retained by XAD-4 (∼8%) resin and the 1 kDa ultrafiltration membrane (∼50%) were similar. The 14C radiocarbon ages of the XAD-8 (mean 3940 ybp), XAD-4 (mean 4048 ybp) and HMW (mean 3270 ybp) fractions are all older than the apparent age of ice-cover formation (2800 ybp). Ultrahigh resolution mass spectrometry showed that compounds with two and three nitrogen atoms in the molecular formulas were common in both the LV-XAD8 and LV-XAD4 fractions, consistent with microbial production and processing. The long-term oxidation of LVBr DOM by abiotic oxidants including perchlorate and chlorate may explain the low portion in the XAD8 fraction and the lack of aromatic carbon, as measured by 13C NMR spectroscopy, found for all but the most hydrophobic fraction, LV-XAD8. Overall, the chemical characteristics of Lake Vida brine DOM suggest that legacy DOM sealed and concentrated within the brine has been altered due to a combination of both biological and abiotic chemical reactions.

  2. Glaciers of Antarctica

    Science.gov (United States)

    Williams, Richard S.; Ferrigno, Jane G.

    1988-01-01

    Of all the world?s continents Antarctica is the coldest, the highest, and the least known. It is one and a half times the size of the United States, and on it lies 91 percent (30,109,800 km3) of the estimated volume of all the ice on Earth. Because so little is known about Antarctic glaciers compared with what is known about glaciers in populated countries, satellite imagery represents a great leap forward in the provision of basic data. From the coast of Antarctica to about 81?south latitude, there are 2,514 Landsat nominal scene centers (the fixed geographic position of the intersection of orbital paths and latitudinal rows). If there were cloud-free images for all these geographic centers, only about 520 Landsat images would be needed to provide complete coverage. Because of cloud cover, however, only about 70 percent of the Landsat imaging area, or 55 percent of the continent, is covered by good quality Landsat images. To date, only about 20 percent of Antarctica has been mapped at scales of 1:250,000 or larger, but these maps do include about half of the coastline. The area of Antarctica that could be planimetrically mapped at a scale of 1:250,000 would be tripled if the available Landsat images were used in image map production. This chapter contains brief descriptions and interpretations of features seen in 62 carefully selected Landsat images or image mosaics. Images were chosen on the basis of quality and interest; for this reason they are far from evenly spaced around the continent. Space limitations allow less than 15 percent of the Landsat imaging area of Antarctica to be shown in the illustrations reproduced in this chapter. Unfortunately, a wealth of glaciological and other features of compelling interest is present in the many hundreds of images that could not be included. To help show some important features beyond the limit of Landsat coverage, and as an aid to the interpretation of certain features seen in the images, 38 oblique aerial photographs

  3. Cosmology from Antarctica

    CERN Document Server

    Wilson, Robert W

    2008-01-01

    Observation of the CMB is central to observational cosmology, and the Antarctic Plateau is an exceptionally good site for this work. The first attempt at CMB observations from the Plateau was an expedition to the South Pole in December 1986 by the Radio Physics Research group at Bell Laboratories. Sky noise and opacity were measured. The results were sufficiently encouraging that in the Austral summer of 1988-1989, three CMB groups participated in the "Cucumber" campaign, where a temporary site dedicated to CMB anisotropy measurements was set up 2 km from South Pole Station. Winter-time observations became possible with the establishment in 1990 of the Center for Astrophysical Research in Antarctica (CARA), a National Science Foundation Science and Technology Center. CARA developed year-round observing facilities in the "Dark Sector", a section of Amundsen-Scott South Pole Station dedicated to astronomical observations. CARA scientists fielded several astronomical instruments: AST/RO, SPIREX, White Dish, Pyth...

  4. Antarctica: The Next Decade

    Science.gov (United States)

    Rowley, Peter D.

    Laurence M. Gould, in charge of United States efforts during the International Geophysical Year (IGY, 1957-1958) and a longterm spokesman for Antarctic science, once remarked that it was the cooperative efforts during the IGY in Antarctica, “coldest of all the continents, that witnessed the first thawing of the cold war.”The Antarctic Treaty, which governs all activities on the continent, was an outgrowth of the IGY. The Treaty—the model international agreement for peaceful cooperation—was signed in 1959 and became effective in 1961. As it nears its historic 30-year anniversary, it has been the subject of a blitz of recent publications, partly because of a general misapprehension that the Treaty might “expire” then and partly the result of controversial negotiations on the recently (June 1988) adopted Convention on the Regulation of Antarctic Mineral Resource Activities (CRAMRA).

  5. Comportamento de linhagens e cultivares de feijoeiro (Phaseolus vulgaris, L. no Vale do Paraíba, SP Behavior of dry bean lines and cultivars in the Paraíba Valley, S. Paulo

    Directory of Open Access Journals (Sweden)

    A. S. Pompeu

    1978-01-01

    Full Text Available Com a finalidade de determinar cultivares mais adequados para plantio nas condições do Vale do Paraíba, no Estado de São Paulo, foram instalados experimentos de competição de linhagens e cultivares em três locais no município de Pindamonhangaba. Durante o período de 1973 a 1976, notou-se a ocorrência de granizo em 1974, prejudicando um dos ensaios, e de geada em 1975, a qual destruiu dois dos três ensaios plantados. Entre as moléstias que ocorrem no feijoeiro, observaram-se a antracnose e a ferrugem. As melhores produções médias foram obtidas pelas linhagens H38C1727 (Mulatinho, H38C1723 (Bico-de-ouro, H40C1722 (Chumbinho e H40C1725 (Preto, e pelos cultivares piratã-2 e piratã-1, com 2.475, 2.308, 2.218, 2.195, 2.177 e 2.164 kg/ha respectivamente. Os cultivares carioca (Diversos e rosinha G-2 (Rosinha tiveram produções de 2.094 e 1.677 kg/ha. Levando-se em consideração a alta capacidade produtiva demonstrada nesses experimentos e em outras regiões do Estado, bem como a disponibilidade de sementes, os cultivares aroana (H40C1722, moruna (H40C1725, piratã-1 e carioca podem ser indicados para plantio em larga escala na região do Vale do Paraíba.With the objective of indicating the best dry bean (Phaseolus vulgaris L. cultivars for the Paraíba Valley, S. Paulo State, trials were planted in three localities in the country of Pindamonhangaba, from 1973 to 1976. From 1973 to 1976 were observed the occurrence of hail in 1974 causing damage in one of the trials, and frost in 1975 that destroyed two of the three experiments planted. Among the pathogens of dry beans, it was noticed the presence of those causing the anthracnose and rust diseases. The best mean yields were observed for H38C1727, H38C1723, H40C1722, H40C1725, 'Piratã-2', and 'Piratã-1' with 2,475, 2,308, 2,218, 2,195, 2,178 and 2,164 kg/ha, respectively. The cultivars Moruna (H4001725, Aroana (H40C1722, Piratã-1 and Carioca can be pointed out for cultivation in

  6. Earth - Ross Ice Shelf, Antarctica

    Science.gov (United States)

    1991-01-01

    This color picture of Antarctica is one part of a mosaic of pictures covering the entire Antarctic continent taken during the hours following Galileo's historic first encounter with its home planet. The view shows the Ross Ice Shelf. An occasional mountain can be seen poking through the ice. It is late spring in Antarctica, so the sun never sets on the frigid, icy continent. This picture was taken on December 8, 1990.

  7. Solar Eclipses Observed from Antarctica

    OpenAIRE

    2013-01-01

    Aspects of the solar corona are still best observed during totality of solar eclipses, and other high-resolution observations of coronal active regions can be observed with radio telescopes by differentiation of occultation observations, as we did with the Jansky Very Large Array for the annular solar eclipse of 2012 May 20 in the US. Totality crossing Antarctica included the eclipse of 2003 November 23, and will next occur on 2021 December 4; annularity crossing Antarctica included the eclip...

  8. Metabolomics and the Legacy of Previous Ecosystems: a Case Study from the Brine of Lake Vida (Antarctica)

    Science.gov (United States)

    Chou, L.; Kenig, F. P. H.; Murray, A. E.; Doran, P. T.; Fritsen, C. H.

    2015-12-01

    The McMurdo Dry Valleys of Antarctica are regarded as one of the best Earth analogs for astrobiological investigations of icy worlds. In the dry valleys, Lake Vida contains an anoxic and aphotic ice-sealed brine that has been isolated for millennia and yet is hosting a population of active microbes at -13˚ C. The biogeochemical processes used by these slow-growing microbes are still unclear. We attempt to elucidate the microbial processes responsible for the survivability of these organisms using metabolomics. Preliminary investigations of organic compounds of Lake Vida Brine (LVBr) was performed using gas chromatography-mass spectrometry (GC-MS) and solid-phase micro-extraction (SPME) GC-MS. LVBr contains a vast variety of lipids and is dominated by low molecular weight compounds. Many of these compounds are biomarkers of processes that took place in Lake Vida prior to evaporation and its cryo-encapsulation. These compounds include dimethylsulfide that is derived from the photosynthate dimethylsulfoniopropionate, dihydroactinidiolide that is derived from a diatom pigment, and 2-methyl-3-ethyl-maleimide that is derived from chlorophyll. These compounds, which dominate the lipid reservoir, represent a legacy from an ecosystem that is different from the current bacterial ecosystem of the brine. The abundance of the legacy compounds in the brine is most likely a reflection of the very slow metabolism of the bacterial community in the cold brine. It is important, thus, to be able to distinguish the legacy metabolites and their diagenetic products from the metabolites of the current ecosystem. This legacy issue is specific to a slow growing microbial ecosystem that cannot process the legacy carbon completely. It applies not only to Lake Vida brine, but other slow growing ecosystems such as other subglacial Antarctic lakes, the Arctic regions, and the deep biosphere.

  9. Ecological Adaptability of Eight Tree Species in Dry and Hot Valley of Jinsha River%金沙江干热河谷区8个造林树种的生态适应性变化

    Institute of Scientific and Technical Information of China (English)

    李昆; 孙永玉; 张春华; 崔永忠

    2011-01-01

    The water ecophysiology of eight tree species growing in dry and hot valley of Jinsha River was studied. The result showed that in rain season the index of water saturation deficit ( WSD) of indigenous tree species Dodonaea viscosa Jacg, and three eucalyptus species were higher than that of the other tree species. The plant with high WSD index and low relative water content (RWC) has strong drought tolerance. Enlargement of the rate of leaf area and fresh leaf weight is beneficial to enhance the drought tolerance of a plant, while increasing the accumulation of dry materials and the density of cytoplasm is also an effective way. Dry and hot stress may induce chlorophyll content reduced, while the chlorophyll content may increase in rainy seasons with increasing the rate of chlorophyll a and chlorophyll b. In dry seasons, the sugar content of test trees is higher than that in rainy seasons and the starch and sugar contents are lower in dry reasons than in rainy reasons except Acacia manguim De Willd. Under the arid condition, the free proline content of 7 tree species increased with different degrees except Eucalyptus urophylla S. T. Blake. The tree species which are prone to wither and defoliation in dry seasons can accumulate more free pro-line. There are more ecophysiological similarities among the seven tree species which are suitable for afforestation except Acacia manguim De Willd. ; and there exists obvious consistency in ecophysiological characteristics amongsame genus. Some ecophysiological characteristics of D. Viscosa Jacg. , the indigenous tree species, are similar to that of Acacia and some others are similar to that of Eucalyptus. Three Eucalyptus species, three Acacia species and D. Viscosa Jacg. Showed stronger ecological adaptability and grow well in dry and hot valley of Jinsha River.%对金沙江干热河谷区8个造林树种的有关生理生态特性进行了研究.结果表明:相思类树种在旱季水分自然饱和亏

  10. Gully erosion processes impacted by vegetation on gully beds based on an in situ scouring experiment in a Dry-hot Valley of Southwest China

    Science.gov (United States)

    Dong, Yifan; Xiong, Donghong; Su, Zhengan

    2015-04-01

    Vegetation can protect soil from water erosion. Some previous researches on the subjects of vegetation and gully erosion were mainly focused on the topography changes cause by vegetation and the conservation effects and techniques. While the mechanics of vegetation effects on the hydraulic processes of gully bed to influence the erosion processes were still not very clear. In this study, an in situ scouring experiment was conducted 11 times assuming a consistent flow condition (7 times with a flow discharge of 83.3L/min and 4 times with a flow discharge of 166.7 L/min on five gully head plots with gully bed lengths of 20 m, which were constructed with similar initial topography (height of the headcuts were 0.5m, the slope of gully beds were from 18.2% to 19.1%) and same soil type (Dry red soil which classified as Rhodoxeralfs in USDA Soil Taxonomy ). Five vegetation condition levels were set on gully bed (the same vegetation density and different lengths of the vegetation sites as 0 m, 4m, 8m, 12m and 16m). Each scouring last 1h and the flow rate, flow depth and flow width were recorded every 10 minutes, after each scouring the topography changes were measured by RTK GPS. The total gully bed erosion volume (TEV) exhibited a significant exponentially decreasing relationship with increasing length of the vegetation sites (VL) due to the similar relationship between the VL and the runoff erosion capacity. The hydrodynamic parameters in the vegetation sites were clearly lower than those in bare sites and caused the average TEV of the vegetation sites to be approximately 3.3 times lower than that of the bare gully bed. However, the vegetation protection efficiency did not increase as the length of the vegetation sites increased. The hydrodynamics of the bare site sections showed a good relationship with TEV, while in the vegetation sites, the relationship was quite weak, indicating that hydraulics conditions were not the main factors influencing gully bed erosion in the

  11. 元谋干热河谷强侵蚀区陷穴发育特征与演化过程%Development Characteristics and Evolution Process of the Sink Holes in Yuanmou Dry-Hot Valley

    Institute of Scientific and Technical Information of China (English)

    舒成强; 张斌; 蒋良群; 刘守江; 罗明良

    2014-01-01

    元谋干热河谷潜蚀地貌发育,是造成当地水土流失的重要原因之一。而陷穴属于潜蚀地貌的一种,因此有必要了解陷穴特征及演化过程。2009-2013年,通过多次现场测定陷穴形态特征、陷穴发育地地形地貌、周边植被特征等,并对土壤进行取样分析。结果表明:1)元谋陷穴主要发育于元谋组地层,土壤具有易崩解性、湿陷性等特征;2)陷穴主要分布于冲沟中上游沟底及支冲沟沟头部位;3)元谋陷穴形态规模总体不大,早期多呈近圆形,中晚期多为椭圆形,直至消失后成为沟中之沟;4)陷穴一般呈单个和串珠状分布,较少出现集群现象;5)演化过程遵循一般事物的发展规律,分为萌芽期、年轻期、成熟期、消亡期4个阶段;6)陷穴发育过程与冲沟、土桥、淘洞等地貌密切相关。%Yuanmou dry-hot valley is located in Jinsha River Basin in the upper reaches of the Yangtze River. It is a typical subtropical climate area with special geographical position and geologic environment. The development of erosional landforms is one of the main reasons for water and soil loss in Yuanmou dry-hot valley. Sink hole is a type of erosional landforms. From 2009 to 2013, field survey was made on the morphological features of the sink holes, the topography and geomorphology of their surrounding areas, and the vegetation and soil around the sink holes. Also the soil of the areas was sampling and analyzed. The results show that the sink holes mainly develop in the strata of Yuanmou formation, where the soil is characterized by its easy disintegration and collapsibility. The sink holes are located at the bottom in the middle and upper reaches of gully and at the top of gully branches. The shape and scale of the sink holes in Yuanmou are generally small. In early stage they are approximately circular in shape, in middle and late stages they are elliptic, and in last stage

  12. 金沙江干热河谷人T林土壤水分研究%A Study on Soil Moisture in Different Plantations in Dry-Hot Valley of Jinsha River

    Institute of Scientific and Technical Information of China (English)

    岳学文; 方海东; 钱坤建; 方晋; 奎建蕊; 潘志贤; 杨艳鲜; 纪中华; 彭辉

    2011-01-01

    以金沙江干热河谷6种人工林为例,采用TRIME-PICO-IPH TDR测定雨季(6-10月)土壤水分,每个样地设3个重复,分析不同人工林内的土壤水分变化特征.罗望子纯林土壤含水量稳定,变异系数小,且含水量较其他人工林高.随着深度的增加,不同人工林之间的土壤含水量差异逐渐变小.根据土壤对降雨的蓄积、利用情况,将0-100cm的土壤剖面分为水分剧烈变化层、弱利用层,草本植物水分利用层、土壤水分微调节层.%Six kinds of plantations in Yuanmou County of Yunnan Province,a typical dry-hot area in the valley of Jinsha River, were selected. Soil moisture was determined with TRIME-PICO-IPH TDR in rainy season (from June to October). Each sample area was selected in triplicate to analysis the variety characteristics of the soil moisture. Soil moisture is vey stable and the variation coefficient is much less in the pure forest of tamarindus indica and its soil moisture content is higher than the others. With the increase of the soil depth,the soil moisture differences among the plantations diminish gradually. The soil profile at 0- 100 cm was divided into 4 layers by saving and using the rainfall of soil, i.e. moisture dramatical-change layer, moisture weak-utilization layer, herbaceous plant moisture utilization layer and soil moisture slight-adjustment layer.

  13. Introduction experiment of leguminous forages in the dry and hot valley of Yuanmou region%元谋干热河谷豆科牧草的引种试验

    Institute of Scientific and Technical Information of China (English)

    龙会英; 张德; 朱红业; 金杰; 史亮涛; 张明忠

    2011-01-01

    2003—2006年元谋干热河谷对16个豆科牧草进行引种试验,结果表明,参试材料中,除蝴碟豆(Centrosemapubescens)、大叶千斤拔(Flemingiamacrophylla)和卵叶山蚂蝗(Desmodiumovalifolium)由于气候差异性不能结实外,其他牧草均能适应该地区种植。其中,银合欢属表现出产量高、叶量大、适口性好等特点。产量排列前3名的牧草为银合欢(Leucaenaleucocephala)K636、新银合欢和热研1号银合欢,干草产量分别为26933.9、24882.6和22%An experiment was conducted to select the suibtable plant legume forages from 16 legume fora ges for the dry and hot valley in the Yuanmou region. This study showed that Centrosema pubescens, Flemingia macropylla, and Desmodium ovalifolium did not seed and the other 13 plant species grew well. Leucaena leucocephala showed the highest yield with a lange number of leaves and good palatability. The top yield was L. leucocephala K636, L. leucocephala, L. leucocephala cv. Reyan No. 1 with 26 93a. 9 kg/ha, 24 882.6 kg/ha, 22 459.2 kg/ha, respectively. The sheep preference for these plants was 5. The Neotononis wightii cv. Tinarroo, Acacia farnesiana and Sesbania grandiflora came to the second due to higher yield and good palatability, and ratio of dry weight to fresh weight and stem/leaf ratio of N. wightii cv. Tinarroo was 0.27 and 0.73. The lowest yield forage was Desmodium ovalifolium with 920.8 kg/ha, and its DW/FW ratio was 1.96. This study suggested that D. ovalifolium was not suitable to be planted in Yuanmou region; and the pest control for Cratylia argentea should be taken during its bloomin5 period to increase pod numbers.

  14. My IGY in Antarctica

    Science.gov (United States)

    Bentley, Charles

    2012-01-01

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

  15. Pulsating star research from Antarctica

    Science.gov (United States)

    Chadid, Merieme

    2017-09-01

    This invited talk discusses the pulsating star research from the heart of Antarctica and the scientific polar challenges in the extreme environment of Antarctica, and how the new polar technology could cope with unresolved stellar pulsation enigmas and evolutionary properties challenges towards an understanding of the mysteries of the Universe. PAIX, the first robotic photometer Antarctica program, has been successfully launched during the polar night 2007. This ongoing program gives a new insight to cope with unresolved stellar enigmas and stellar oscillation challenges with a great opportunity to benefit from an access to the best astronomical site on Earth, Dome C. PAIX achieves astrophysical measurement time-series of stellar fields, challenging photometry from space. A continuous and an uninterrupted series of multi-color photometric observations has been collected each polar night - 150 days - without regular interruption, Earth's rotation effect. PAIX shows the first light curve from Antarctica and first step for the astronomy in Antarctica giving new insights in remote polar observing runs and robotic instruments towards a new technology.

  16. Dry Eye

    Science.gov (United States)

    ... Eye > Facts About Dry Eye Facts About Dry Eye This information was developed by the National Eye ... the best person to answer specific questions. Dry Eye Defined What is dry eye? Dry eye occurs ...

  17. Activity and Spatial Distribution of Candida antarctica Lipase B Immobilized on Macroporous Organic Polymeric Adsorbents

    DEFF Research Database (Denmark)

    Nielsen, Anne Veller Friis; Andric, Pavle; Munk Nielsen, Per

    2014-01-01

    A systematic study of the influence of carrier particle size (500 − 850 μ m) and enzyme load (26 200 − 66 100 lipase activity units (LU)/g dry carrier) on the content and activity of Candida antarctica lipase B (CALB) immobilized by adsorption onto macroporous poly(methyl methacrylate) (PMM...

  18. Study on Key Technology of Orangery Intercropping Models in Binchuan Dry Hot Valley%宾川干热河谷区柑橘园套种模式关键技术研究

    Institute of Scientific and Technical Information of China (English)

    冯光恒; 杨艳鲜; 江功武; 徐兴才; 杨红钧

    2013-01-01

    为了充分利用宾川干热河谷区丰富的光、热、水、土资源,提高柑橘园建园初期(1~3年)的综合效益和复种指数,促进果农增收,采用“乔(灌)+农经作物”的建园方法,建立柑橘园套种模式,提出典型模式建设关键技术,并进行效益分析.结果表明:柑橘园前3年幼树期进行作物套种,能以短养长,使柑橘园每年平均增收32 340元/hm2,套种经济作物每年最高增收达55 200元/hm2;能改善柑橘园小气候,培肥土壤;改善土壤物理性状;抑制杂草,减少虫害,保持果园生态系统平衡,保护人类健康;提高柑橘园的资源利用率,节本增效,社会效益得到充分体现.%In order to made the best of abundant photo-thermal resources,water and soil resources in Binchuan Dry Hot Valley,and improved comprehensive benefits and multiple cropping index in 1 to 3 years of orangery development preliminary stage,promoted orchardist increase income,the study adopted the orangery intercropping ways of "arbor(shrub) + agricultural and industrial crop",set up orangery intercropping models,put forward key technology of representative models,carried out benefit analysis.The results showed that the peasants got annual average income 32 340 CNY/hm2 by intercropping in the front 3 years,and the income from intercropping supplied management funds for the orangery.The most annual income was 55 200 CNY/hm2 if the intercropping crop was cash crop.The intercropping ameliorated the microclimate and soil physical behavior of the orangery,and increased the soil nutrient.The intercropping could control rank grass,and reduce insect pest,and keep the balance of orangery ecosystem,and protect the human health.The orangery intercropping not only improved resource utilization rate of the orangery,but also saved costing,and embodied social benefits fully.

  19. Antarctica: Chile’s Claim,

    Science.gov (United States)

    1987-01-01

    Marie Byrd Land is be- low sea level and covered by a sheath of ice 600 to 4,000 meters (1,968 to 13,120 feet) thick. * This sheath of ice extends below...Channel to sulphurs lead, silver stratiform bodies Spring Point, Trans- in sedimentary Antarctica Mountain and volcanic rocks Ultra- Chrome , Stratified en

  20. Pine Island Glacier, Antarctica

    Science.gov (United States)

    2001-01-01

    This pair of MISR images of the Pine Island Glacier in western Antarctica was acquired on December 12, 2000 during Terra orbit 5246. At left is a conventional, true-color image from the downward-looking (nadir) camera. The false-color image at right is a composite of red band data taken by the MISR forward 60-degree, nadir, and aftward 60-degree cameras, displayed in red, green, and blue colors, respectively. Color variations in the left (true-color) image highlight spectral differences. In the multi-angle composite, on the other hand, color variations act as a proxy for differences in the angular reflectance properties of the scene. In this representation, clouds show up as light purple. Blue to orange gradations on the surface indicate a transition in ice texture from smooth to rough. For example, the bright orange 'carrot-like' features are rough crevasses on the glacier's tongue. In the conventional nadir view, the blue ice labeled 'rough crevasses' and 'smooth blue ice' exhibit similar coloration, but the multi-angle composite reveals their different textures, with the smoother ice appearing dark purple instead of orange. This could be an indicator of different mechanisms by which this ice is exposed. The multi-angle view also reveals subtle roughness variations on the frozen sea ice between the glacier and the open water in Pine Island Bay.To the left of the 'icebergs' label are chunks of floating ice. Additionally, smaller icebergs embedded in the frozen sea ice are visible below and to the right of the label. These small icebergs are associated with dark streaks. Analysis of the illumination geometry suggests that these streaks are surface features, not shadows. Wind-driven motion and thinning of the sea ice in the vicinity of the icebergs is one possible explanation.Recently, Robert Bindschadler, a glaciologist at the NASA Goddard Space Flight Center discovered in Landsat 7 imagery a newly-formed crack traversing the Pine Island Glacier. This crack is

  1. The pathogen causing mango malformation in Jinsha River Dry-hot Valley, China%金沙江干热河谷地区芒果畸形病的病原菌

    Institute of Scientific and Technical Information of China (English)

    杨顺锦; 詹儒林; 柳凤; 赵艳龙; 常金梅; 何衍彪

    2011-01-01

    从金沙江干热河谷地区采集芒果畸形病组织,运用柯赫氏法则证实分离物MG6为该病的致病菌.菌株MG6在马铃薯蔗糖琼脂培养基(PSA)上菌丝白色,无色素产生,米饭培养基浅粉红色;在康乃馨叶片培养基(CLA)上以单瓶梗或复瓶梗假头状产孢,不产生链状孢子;小型分生孢子卵形或长椭圆形,具0-1个分隔,3.1-10.2×1.5-2.2μm;大型分生孢子呈镰刀形,通常3个分隔,18-38×1.8-2.4μm.EF-Iα测序结果在Fusarium数据库中进行同源性分析显示,菌株MG6与F.mangiferae的同源性最高,达99.68%.综合培养性状、形态学特征和EF-Iα序列分析,将菌株MG6鉴定为Fusarium mangiferae.%Mango tissue samples infected by malformation disease were collected from Jinsha River Dry-hot Valley and the fungal strains were isolated after surface sterilization. Isolate MG6 was confirmed to be the pathogen of this disease through Koch's rules.Based on morphological characteristics and EF-1α sequencing, isolate MG6 was identified as Fusarium mangiferae. The colony of the strain was white and pigment was not formed on Potato Sugar Agar (PSA). Pigmentation on rice medium was pink. On Carnation Leaf Agar (CLA) medium, microconidia formed false head on branched monophialides or polyphialidas, and conidia in chains were not observed. Microconidia are ovate to long-oval, 0-1-septate, 3.1-10.2× 1.5-2.2μm. Macroconidia are falculate, 3-5-septate,18-38× 1.8-2.4μm. Chlamydospores are absent. The EF-1α region of the pathogen was amplified and sequenced. A BLAST search through the Fusarium database (http://isolate.fusariumdb.org) showed that the identity of EF-1α sequence of isolate MG6 to that of Fusarium mangiferae NRRL 25226, the closest match was 99.68%, confirming the morphological identification of the isolate.

  2. 金沙江干热河谷银合欢人工林对土壤养分的影响%Effects of Soil Nutrients on Planted Leucaena leucocephala Forest in the Dry-hot Jinshajiang River Valley

    Institute of Scientific and Technical Information of China (English)

    方海东; 魏雅丽; 刘刚才; 杨艳鲜; 潘志贤; 纪中华

    2011-01-01

    通过干热河谷银合欢人工林对土壤改良效应5年的研究,结果表明:银合欢林具有很好的土壤改良效应,土壤有机质明显高于CK,在0~20 cm,20~40cm和40~60cm的土层中,比CK分别高52.61%,51.09%和43.52%,土壤有机质随着土壤深度的增加而减少.pH在0~20cm,20~40cm和40~60cm的土层中,比CK分别低8.28%,2.41%和2.19%.全N含量上层土壤明显高于下层,水解N比CK高43.75%,随着土壤深度的增加,水解N呈现下降趋势,并具有显著性相关关系.全P含量比CK高0.05mg/kg,相差不是很明显.有效P含量与CK相差不是很明显,在不同土层深度有效P含量的变化非常一致.全K含量比CK高0.98 mg/kg,银合欢的生长对土壤全K含量的影响并不明显.速效K含量平均为136.79 mg/kg,变化幅度较大,比CK高69.45 mg/kg,银合欢的生长对土壤速效K含量的影响明显.%The soil improvement effect on the planted Leucaena leucocephala forest in the dry-hot Jinshajiang River Valley was researched for five years. The results show that the soil improvement effect on the forest was obvious. Soil organic matter content was obviously higher than CK, its values at soil depths of 0 - 20 cm, 20-40 cm and 40 -60 cm under the forest were 52. 61% , 51. 09% and 43. 52% higher than CK respectively, and it decreased with the increase of soil depth. At soil depths of 0 -20 cm, 20 -40 cm and 40 -60 cm, the Ph values of forest soil were 8. 28% , 2.41% and 2. 19% lower than CK respectively. Total soil N content was 43. 75% higher than CK, it decreased with the increase of soil depth, and there was a significant correlation between total soil N content and soil depth. Total soil P content was 0. 05 mg/kg higher than CK only. The difference of available P content between the forest soil and CK was not obvious. Total soil K content was 0. 98 mg/kg higher than CK, and the effect of total K content on the forest was not obvious. The available K content in the forest soil was 136

  3. 金沙江干热河谷扭黄茅花粉微形态及活力研究%Study on the Pollen Micro-morphological Characters and Viability of Heteropogon contortus from Jinshajiang Dry-hot Valley

    Institute of Scientific and Technical Information of China (English)

    谢勇; 毕玉芬; 浦卫琼; 王海宁

    2012-01-01

    [目的]为丰富抗旱耐热的育种材料来源提供依据.[方法]对来自金沙江干热河谷不同地区的扭黄茅花粉形态进行了电镜扫描观察,并采用碘-碘化钾(I-KI)染色法进行活力测定.[结果]扭黄茅花粉粒为中等大小花粉粒,花粉形态为近球型,花粉壁纹饰为粗糙型,萌发孔为单一萌发孔,萌发孔有孔环,表明扭黄茅具有进化性状,但是进化程度较低,仍属于原始状态,与扭黄茅为野生状态相一致.金沙江沿岸永胜、攀枝花、元谋扭黄茅的花粉活力为80.00% ~ 87.10%,差异不显著(P>0.05).永胜地区扭黄茅花粉活力为82.19%~87.00%,不同扭黄茅材料间的花粉活力差异也不显著(P>0.05).[结论]金沙江沿岸各地区的扭黄茅花粉形态与结构基本一致,表明其是一个自然类群.%[Objective] The research aimed to provide basis for enriching the breeding materials with heat-resistance and drought-resistance. [ Method ] The pollen morphology of Heteropogon contortus from different areas of Jinshajiang dry-hot valley was observed by using electron microscope scanning. And the pollen viability was measured by using iodine-iodine kalium staining method. [ Result] The pollen grains were medium size, spheroidal shape, with rough type extine sculpture and single germinal aperture and annular ring. This indicated that H. contortus had the typical evolutionary character, with low evolutionary level, belonging to the original state, which was accordant with the wild strain of//. contortus. The pollen viability of H. contortus from Yongsheng, Panzhihua and Yuanmou along Jinshajiang River was 80. 00% - 87. 10% , without significant difference(P >0. 05). The pollen viability of H, contortus from Yongsheng area was 82. 19% -87.00% , and the difference of pollen viability among different materials of H. contortus was not significant P > 0. 05 ) . [ Conclusion ] The pollen grains micro-morphological characters and its viability of H

  4. U.S. Geological Survey scientific activities in the exploration of Antarctica: 1946-2006 record of personnel in Antarctica and their postal cachets: U.S. Navy (1946-48, 1954-60), International Geophysical Year (1957-58), and USGS (1960-2006)

    Science.gov (United States)

    Meunier, Tony K.; Williams, Richard S.; Ferrigno, Jane G.

    2007-01-01

    Antarctica, a vast region encompassing 13.2 million km2 (5.1 million mi2), is considered to be one of the most important scientific laboratories on Earth. During the past 60 years, the USGS, in collaboration and with logistical support from the National Science Foundation's Office of Polar Programs, has sent 325 USGS scientists to Antarctica to work on a wide range of projects: 169 personnel from the NMD (mostly aerial photography, surveying, and geodesy, primarily used for the modern mapping of Antarctica), 138 personnel from the GD (mostly geophysical and geological studies onshore and offshore), 15 personnel from the WRD (mostly hydrological/glaciological studies in the McMurdo Dry Valleys), 2 personnel from the BRD (microbiological studies in the McMurdo Dry Valleys), and 1 person from the Director's Office (P. Patrick Leahy, Acting Director, 2005–06 austral field season). Three GD scientists and three NMD scientists have carried out field work in Antarctica 9 or more times: John C. Behrendt (15), who started in 1956–57 and published two memoirs (Behrendt, 1998, 2005), Arthur B. Ford (10), who started in 1960–61, and Gary D. Clow (9), who started in 1985–86; Larry D. Hothem (12), who began as a winter-over geodesist at Mawson Station in 1968–69, and Jerry L. Mullins (12), who started in 1982–83 and followed in the legendary footsteps of his NMD predecessor, William R. MacDonald (9), who started in 1960–61 and supervised the acquisition of more than 1,000,000 square miles of aerial photography of Antarctica. This report provides a record as complete as possible, of USGS and non-USGS collaborating personnel in Antarctica from 1946–2006, the geographic locations of their work, and their scientific/engineering disciplines represented. Postal cachets for each year follow the table of personnel and scientific activities in the exploration of Antarctica during those 60 years. To commemorate special events and projects in Antarctica, it became an

  5. U.S. Geological Survey scientific activities in the exploration of Antarctica: 1946-2006 record of personnel in Antarctica and their postal cachets: U.S. Navy (1946-48, 1954-60), International Geophysical Year (1957-58), and USGS (1960-2006)

    Science.gov (United States)

    Meunier, Tony K.; Williams, Richard S.; Ferrigno, Jane G.

    2007-01-01

    Antarctica, a vast region encompassing 13.2 million km2 (5.1 million mi2), is considered to be one of the most important scientific laboratories on Earth. During the past 60 years, the USGS, in collaboration and with logistical support from the National Science Foundation's Office of Polar Programs, has sent 325 USGS scientists to Antarctica to work on a wide range of projects: 169 personnel from the NMD (mostly aerial photography, surveying, and geodesy, primarily used for the modern mapping of Antarctica), 138 personnel from the GD (mostly geophysical and geological studies onshore and offshore), 15 personnel from the WRD (mostly hydrological/glaciological studies in the McMurdo Dry Valleys), 2 personnel from the BRD (microbiological studies in the McMurdo Dry Valleys), and 1 person from the Director's Office (P. Patrick Leahy, Acting Director, 2005–06 austral field season). Three GD scientists and three NMD scientists have carried out field work in Antarctica 9 or more times: John C. Behrendt (15), who started in 1956–57 and published two memoirs (Behrendt, 1998, 2005), Arthur B. Ford (10), who started in 1960–61, and Gary D. Clow (9), who started in 1985–86; Larry D. Hothem (12), who began as a winter-over geodesist at Mawson Station in 1968–69, and Jerry L. Mullins (12), who started in 1982–83 and followed in the legendary footsteps of his NMD predecessor, William R. MacDonald (9), who started in 1960–61 and supervised the acquisition of more than 1,000,000 square miles of aerial photography of Antarctica. This report provides a record as complete as possible, of USGS and non-USGS collaborating personnel in Antarctica from 1946–2006, the geographic locations of their work, and their scientific/engineering disciplines represented. Postal cachets for each year follow the table of personnel and scientific activities in the exploration of Antarctica during those 60 years. To commemorate special events and projects in Antarctica, it became an

  6. Dioszegia antarctica sp. nov. and Dioszegia cryoxerica sp. nov., psychrophilic basidiomycetous yeasts from polar desert soils in Antarctica

    Science.gov (United States)

    Rodriguez, Russell J.; Connell, L.; Redman, R.; Barrett, A.; Iszard, M.; Fonseca, A.

    2010-01-01

    During a survey of the culturable soil fungal population in samples collected in Taylor Valley, South Victoria Land, Antarctica, 13 basidiomycetous yeast strains with orange-coloured colonies were isolated. Phylogenetic analyses of internal transcribed spacer (ITS) and partial LSU rRNA gene sequences showed that the strains belong to the Dioszegia clade of the Tremellales (Tremellomycetes, Agaricomycotina), but did not correspond to any of the hitherto recognized species. Two novel species, Dioszegia antarctica sp. nov. (type strain ANT-03-116T =CBS 10920T =PYCC 5970T) and Dioszegia cryoxerica sp. nov. (type strain ANT-03-071T =CBS 10919T =PYCC 5967T), are described to accommodate ten and three of these strains, respectively. Analysis of ITS sequences demonstrated intrastrain sequence heterogeneity in D. cryoxerica. The latter species is also notable for producing true hyphae with clamp connections and haustoria. However, no sexual structures were observed. The two novel species can be considered obligate psychrophiles, since they failed to grow above 20 °C and grew best between 10 and 15 °C.

  7. 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 3 mm 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.

  8. Soils of Marie Byrd Land, West Antarctica

    Science.gov (United States)

    Lupachev, A. V.; Abakumov, E. V.

    2013-10-01

    Soils of Marie Byrd Land-one of the remotest and difficultly accessible regions of Antarctica-were investigated in the area of the mothballed Russkaya station located to the south of 74° S. Despite the extremely severe wind regime (the average wind velocity is 13 m/s, and the maximum wind velocity is up to 60 m/s), the projective cover of vegetation in the area of the station averages 25-40% and reaches 60-80% in some places. The phenomena of physical weathering of the bedrock-exfoliation, stone pavements, residual rocks exposed by wind (hoodoos), and others-are clearly manifested. In most of the described soils, normal organic and organomineral horizons are absent. The soil profiles represent the mixture of the residues of mosses and lichens and the gravelly eluvium. The fine earth material is blown out of the surface horizons by strong winds; its residual accumulation takes place in the middle and lower parts of the profiles. The classification position of these soils is open to argument; they are close to Petrozems and Lithozems. Most of the profiles are underlain by the massive or slightly disintegrated bedrock with dry permafrost at a depth of 20 to 50 cm. Soils with dry permafrost comprise about 75% of the surveyed area. In separate loci in the depressions of the local mesorelief and on gentle slopes, the soils with clearly expressed cryoturbation features are developed; their profiles are underlain by the ice-rich permafrost and compose about 15% of the surveyed area. Anthropogenically disturbed soils and soils polluted with petroleum hydrocarbons, heavy metals, and other pollutants occupy about 10% of the surveyed area.

  9. Valley precession and valley polarization in graphene with inter-valley coupling

    Science.gov (United States)

    Wu, Qing-Ping; Liu, Zheng-Fang; Chen, Ai-Xi; Xiao, Xian-Bo; Zhang, Heng; Miao, Guo-Xing

    2017-10-01

    We theoretically investigate the valley precession and valley polarization in graphene under inter-valley coupling. Our results show that the inter-valley coupling can induce valley polarization in graphene and also precess valleys in real space in a manner similar to the Rashba spin-orbit interaction rotating spins. Moreover, using strain modulation, we can achieve high valley polarization with large valley-polarized currents. These findings provide a new way to create and manipulate valley polarization in graphene.

  10. Potential methane reservoirs beneath Antarctica.

    Science.gov (United States)

    Wadham, J L; Arndt, S; Tulaczyk, S; Stibal, M; Tranter, M; Telling, J; Lis, G P; Lawson, E; Ridgwell, A; Dubnick, A; Sharp, M J; Anesio, A M; Butler, C E H

    2012-08-30

    Once thought to be devoid of life, the ice-covered parts of Antarctica are now known to be a reservoir of metabolically active microbial cells and organic carbon. The potential for methanogenic archaea to support the degradation of organic carbon to methane beneath the ice, however, has not yet been evaluated. Large sedimentary basins containing marine sequences up to 14 kilometres thick and an estimated 21,000 petagrams (1 Pg equals 10(15) g) of organic carbon are buried beneath the Antarctic Ice Sheet. No data exist for rates of methanogenesis in sub-Antarctic marine sediments. Here we present experimental data from other subglacial environments that demonstrate the potential for overridden organic matter beneath glacial systems to produce methane. We also numerically simulate the accumulation of methane in Antarctic sedimentary basins using an established one-dimensional hydrate model and show that pressure/temperature conditions favour methane hydrate formation down to sediment depths of about 300 metres in West Antarctica and 700 metres in East Antarctica. Our results demonstrate the potential for methane hydrate accumulation in Antarctic sedimentary basins, where the total inventory depends on rates of organic carbon degradation and conditions at the ice-sheet bed. We calculate that the sub-Antarctic hydrate inventory could be of the same order of magnitude as that of recent estimates made for Arctic permafrost. Our findings suggest that the Antarctic Ice Sheet may be a neglected but important component of the global methane budget, with the potential to act as a positive feedback on climate warming during ice-sheet wastage.

  11. A novel adenovirus in Chinstrap penguins (Pygoscelis antarctica) in Antarctica.

    Science.gov (United States)

    Lee, Sook-Young; Kim, Jeong-Hoon; Park, Yon Mi; Shin, Ok Sarah; Kim, Hankyeom; Choi, Han-Gu; Song, Jin-Won

    2014-05-07

    Adenoviruses (family Adenoviridae) infect various organ systems and cause diseases in a wide range of host species. In this study, we examined multiple tissues from Chinstrap penguins (Pygoscelis antarctica), collected in Antarctica during 2009 and 2010, for the presence of novel adenoviruses by PCR. Analysis of a 855-bp region of the hexon gene of a newly identified adenovirus, designated Chinstrap penguin adenovirus 1 (CSPAdV-1), showed nucleotide (amino acid) sequence identity of 71.8% (65.5%) with South Polar skua 1 (SPSAdV-1), 71% (70%) with raptor adenovirus 1 (RAdV-1), 71.4% (67.6%) with turkey adenovirus 3 (TAdV-3) and 61% (61.6%) with frog adenovirus 1 (FrAdV-1). Based on the genetic and phylogenetic analyses, CSPAdV-1 was classified as a member of the genus, Siadenovirus. Virus isolation attempts from kidney homogenates in the MDTC-RP19 (ATCC® CRL-8135™) cell line were unsuccessful. In conclusion, this study provides the first evidence of new adenovirus species in Antarctic penguins.

  12. A Novel Adenovirus in Chinstrap Penguins (Pygoscelis antarctica in Antarctica

    Directory of Open Access Journals (Sweden)

    Sook-Young Lee

    2014-05-01

    Full Text Available Adenoviruses (family Adenoviridae infect various organ systems and cause diseases in a wide range of host species. In this study, we examined multiple tissues from Chinstrap penguins (Pygoscelis antarctica, collected in Antarctica during 2009 and 2010, for the presence of novel adenoviruses by PCR. Analysis of a 855-bp region of the hexon gene of a newly identified adenovirus, designated Chinstrap penguin adenovirus 1 (CSPAdV-1, showed nucleotide (amino acid sequence identity of 71.8% (65.5% with South Polar skua 1 (SPSAdV-1, 71% (70% with raptor adenovirus 1 (RAdV-1, 71.4% (67.6% with turkey adenovirus 3 (TAdV-3 and 61% (61.6% with frog adenovirus 1 (FrAdV-1. Based on the genetic and phylogenetic analyses, CSPAdV-1 was classified as a member of the genus, Siadenovirus. Virus isolation attempts from kidney homogenates in the MDTC-RP19 (ATCC® CRL-8135™ cell line were unsuccessful. In conclusion, this study provides the first evidence of new adenovirus species in Antarctic penguins.

  13. Diversity of soil yeasts isolated from South Victoria Land, Antarctica

    Science.gov (United States)

    Connell, L.; Redman, R.; Craig, S.; Scorzetti, G.; Iszard, M.; Rodriguez, R.

    2008-01-01

    Unicellular fungi, commonly referred to as yeasts, were found to be components of the culturable soil fungal population in Taylor Valley, Mt. Discovery, Wright Valley, and two mountain peaks of South Victoria Land, Antarctica. Samples were taken from sites spanning a diversity of soil habitats that were not directly associated with vertebrate activity. A large proportion of yeasts isolated in this study were basidiomycetous species (89%), of which 43% may represent undescribed species, demonstrating that culturable yeasts remain incompletely described in these polar desert soils. Cryptococcus species represented the most often isolated genus (33%) followed by Leucosporidium (22%). Principle component analysis and multiple linear regression using stepwise selection was used to model the relation between abiotic variables (principle component 1 and principle component 2 scores) and yeast biodiversity (the number of species present at a given site). These analyses identified soil pH and electrical conductivity as significant predictors of yeast biodiversity. Species-specific PCR primers were designed to rapidly discriminate among the Dioszegia and Leucosporidium species collected in this study. ?? 2008 Springer Science+Business Media, LLC.

  14. 干热河谷乡土树种清香木幼苗生长对不同水分梯度的响应%Responses of Pistacia weinmannifolia seedling to different water gradient in dry-hot valley

    Institute of Scientific and Technical Information of China (English)

    王妍; 张超; 李昆

    2014-01-01

    根据土壤的田间持水量设置不同的土壤水分含量梯度,通过对不同梯度下清香木幼苗的株高、叶片性状、生物量以及幼苗生长状态的观测和分析,旨在探讨清香木幼苗在水分缺失及过量的情况下对水分的利用情况及清香木幼苗在不同水分条件下生长的性状,了解幼苗对水分过多或过少胁迫的响应,以期在云南干热河谷地区的植被恢复、清香木的培育种植中能提供一定的理论指导和技术参考。研究结果表明,清香木幼苗期需水量较多,在田间持水量充足的条件下,幼苗生长较好,在相对田间持水量较小的条件下,幼苗虽然较正常水分条件下生长减慢,但仍能生长。研究结果表明,清香木幼苗对极端干旱的耐受性要高于对极端降水,同时随植株的生长,清香木对水分需求的敏感度降低。研究还表明,在不构成胁迫的环境中,幼苗的地上部分生物量的增加明显高于地下部分的生物量的增加,而在水分过多或过少胁迫下幼苗的地下部分生物量的增加会高于地上部分,而且在胁迫强度和胁迫时间的推移下,表现的更为明显,此种适应对策可以帮助幼苗吸收更多的水分和养分,以及减少蒸腾等损耗,从而适应逆境。%Seedling plant height, leaf traits, biomass, and seedling growth state of Pistacia weinmannifolia under different precipitation gradients were observed and analyzed in order to explore the seedling water use efficiency traits in the case of water loss or excessive condition and response to the water stress in dry and hot valley in Yunnan province, and which can provide some theoretical guidance and technical reference to region vegetation restoration. The results show that in the early stage, P. weinmannifolia seedling requires high water condition and better seedling growth in conditions of adequate moisture, but in drought conditions, seedling

  15. Don Juan Pond, Antarctica: Near-surface CaCl2-brine feeding Earth's most saline lake and implications for Mars

    Science.gov (United States)

    Dickson, James L.; Head, James W.; Levy, Joseph S.; Marchant, David R.

    2013-01-01

    The discovery on Mars of recurring slope lineae (RSL), thought to represent seasonal brines, has sparked interest in analogous environments on Earth. We report on new studies of Don Juan Pond (DJP), which exists at the upper limit of ephemeral water in the McMurdo Dry Valleys (MDV) of Antarctica, and is adjacent to several steep-sloped water tracks, the closest analog for RSL. The source of DJP has been interpreted to be deep groundwater. We present time-lapse data and meteorological measurements that confirm deliquescence within the DJP watershed and show that this, together with small amounts of meltwater, are capable of generating brines that control summertime water levels. Groundwater input was not observed. In addition to providing an analog for RSL formation, CaCl2 brines and chloride deposits in basins may provide clues to the origin of ancient chloride deposits on Mars dating from the transition period from “warm/wet” to “cold/dry” climates. PMID:23378901

  16. Energy valley in transition

    NARCIS (Netherlands)

    Verwayen, Barbara

    2006-01-01

    The Energy Valley foundation was born in 2004. It functions as a catalyst and platform for private and public organisations. It has a supporting and facilitating role in realising projects on energy conservation and sustainable energy. The Energy Valley a

  17. Recent accumulation rate at Dome A, Antarctica

    Institute of Scientific and Technical Information of China (English)

    HOU ShuGui; LI YuanSheng; XIAO CunDe; REN JiaWen

    2007-01-01

    Based on the horizon of β activity and the density profiles, recent accumulation rate at Dome A, Antarctica is calculated to be 0.023 m water equivalent per year. This value is comparative to the accumulation rates deduced from the other inland sites of Antarctica. Clear-sky precipitation (or diamond dust) dominates the total precipitation at Dome A region. We speculate Dome A as a potential site to discover the oldest ice in Antarctica due to its tremendous ice thickness (>3000 m), extremely low accumulation rate, and low ice velocity.

  18. PRELIMINARY RESULTS OF HYDROGRAPHY UNDER FAST ICE IN LUTZOW-HOLM BAY, ANTARCTICA IN 1990

    OpenAIRE

    タキザワ, タカトシ; ウシオ, シュウキ; カワムラ, トシユキ; オオシマ; オノ, ノブオ; カワグチ, サダオ; Takatoshi, TAKIZAWA; Shuki, USHIO; Toshiyuki, Kawamura; Kay I., OHSHIMA; Nobuo, Ono; Sadao, Kawaguchi

    1992-01-01

    Seasonal variations in water structure under fast ice in Lutzow-Holm Bay, Antarctica, were observed from April to December, 1990. Two warm and oxygen-poor waters were observed. One is warmer water with temperatures higher than 0℃, salinities of more than 34.6 and oxygen less than 6 ml/l, and is found in the bottom layer deeper than 700m in the Shirase Submarine Valley. The other is found in the upper layer with temperatures of -1.4∿ -1.5℃, salinities of around 34.2 and oxygen of 6.3-6.9ml...

  19. Iron Meteorites and Upwelling in Antarctica

    Science.gov (United States)

    Gourlay, B. S.; Behr, E.; Mardon, A.; Behr, E.

    2016-09-01

    In Antarctica, a meteorite stranding zone, stone meteorites are more common than iron. Dr. Evatt's team suggests that the heat conductivity of iron may be opposing the upwelling effects so iron meteorites sink under the ice unlike the stone ones.

  20. Geoethical approach to mineral activities in Antarctica

    Science.gov (United States)

    Talalay, Pavel

    2013-04-01

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

  1. Dating buried glacier ice using cosmogenic 3He in surface clasts: Theory and application to Mullins Glacier, Antarctica

    Science.gov (United States)

    Mackay, Sean L.; Marchant, David R.

    2016-05-01

    We develop a modeling framework to describe the accumulation of terrestrial cosmogenic 3He in Antarctic debris-covered glaciers. The framework helps quantify the expected range in cosmogenic-nuclide inventories for measured clasts at the surface of supraglacial debris. We first delineate the physical factors that impact clast movement within, and on top of, debris-covered glaciers, including the effects of (1) ice ablation, (2) erosion at the debris surface, and (3) stochastic geomorphic processes that impact clast movement within and on top of supraglacial debris; we then explicitly calculate the impact of each process in altering the total inventory of cosmogenic nuclides in surface clasts. Assuming basic elements of ice-dynamics and debris entrainment are known, the model results provide an estimate for the total accumulation of cosmogenic nuclides, as well as the expected range in nuclide inventories, for any clast at the surface of debris-covered glaciers. Because the values are quantified, the approach can be applied to help evaluate the robustness of existing and future cosmogenic datasets applied to these systems. As a test, we applied our model framework towards Mullins Glacier, a cold-based debris-covered alpine glacier in the Dry Valleys of Antarctica. Our simulated values for cosmogenic-nuclide inventories compare well with those previously measured from fifteen surface cobbles along Mullins Glacier (3He), both in terms of expected ranges and absolute values, and suggest that our model framework adequately incorporates most of the complicating factors that impact cosmogenic datasets for cold-based, debris-covered glaciers. Relating these cosmogenic-nuclide inventories to ice ages, the results show that ice within Mullins Glacier increases non-linearly, ranging from 12 ka to ∼220 ka in areas of active flow, to ≫1.6 Ma in areas of slow-moving-to-stagnant ice.

  2. Potential seaways across West Antarctica

    Science.gov (United States)

    Vaughan, David G.; Barnes, David K. A.; Fretwell, Peter T.; Bingham, Robert G.

    2011-10-01

    The West Antarctic ice sheet (WAIS) has long been considered vulnerable to rapid retreat and today parts are rapidly losing ice. Projection of future change in WAIS is, however, hampered by our poor understanding of past changes, especially during interglacial periods that could be analogs for the future, but which undoubtedly provide an opportunity for testing predictive models. We consider how ice-loss would open seaways across WAIS; these would likely alter Southern Ocean circulation and climate, and would broadly define the de-glacial state, but they may also have left evidence of their existence in the coastal seas they once connected. We show the most likely routes for such seaways, and that a direct seaway between Weddell and Ross seas, which did not pass through the Amundsen Sea sector, is unlikely. Continued ice-loss at present rates would open seaways between Amundsen and Weddell seas (A-W), and Amundsen and Bellingshausen seas (A-B), in around one thousand years. This timescale indicates potential future vulnerability, but also suggests seaways may have opened in recent interglacial periods. We attempt to test this hypothesis using contemporary bryozoan species assemblages around Antarctica, concluding that anomalously high similarity in assemblages in the Weddell and Amundsen seas supports recent migration through A-W. Other authors have suggested opening of seaways last occurred during Marine Isotope Stage 7a (209 ka BP), but we conclude that opening could have occurred in MIS 5e (100 ka BP) when Antarctica was warmer than present and likely contributed to global sea levels higher than today.

  3. The separation of Ceylon from Antarctica

    Science.gov (United States)

    Schreider, Al. A.; Schreider, A. A.; Boiko, A. N.; Kashintsev, G. L.; Evsenko, E. I.

    2011-08-01

    The geometry of the junction between Ceylon and Antarctica during the Gondwanaland breakup is still under discussion. Analysis of the available geological-geophysical materials has allowed the peculiarities of Ceylon separation from Antarctica to be characterized, the new paleogeodynamical reconstruction to be elaborated, and a prognosis of the tectonic structure and mineral resources in the areas of Antarctic coast that were adjacent to Ceylon to be made.

  4. The Jurassic history of the Africa-Antarctica corridor — new constraints from magnetic data on the conjugate continental margins

    Science.gov (United States)

    Leinweber, Volker Thor; Jokat, Wilfried

    2012-03-01

    Finding the best fit for East- and West-Gondwana requires a detailed knowledge of the initial Jurassic movements between Africa and Antarctica. This study presents results of systematic and densely spaced aeromagnetic measurements, which have been conducted in 2009/2010 across the Astrid Ridge (Antarctica) and in the western Riiser-Larsen Sea to provide constraints for the early seafloor spreading history between both continents. The data reveal different magnetic signatures of the northern and southern parts of the Astrid Ridge, which are separated by the Astrid Fracture Zone. The southern part is weakly magnetised, corresponding to the low amplitude anomaly field of the southwestern Riiser-Larsen Sea. In contrast, the northern Astrid Ridge bears strong anomalies of positive value. Furthermore, several sets of trends are visible in the data. In the Mozambique Channel, we extended the existing magnetic spreading anomaly identifications. Combined with the spreading anomalies in the conjugate Riiser-Larsen Sea, they were used to establish a new model of the relative movements of Africa and Antarctica after the breakup of Gondwana in Jurassic times. A detailed model for the emplacement of the Mozambique Ridge is now incorporated. The model postulates a tight fit between Africa and Antarctica and two stages of breakup, the first of which lasting until ~ 159 Ma (M33n). During this stage, Antarctica rotated anticlockwise with respect to Africa. The Grunehogna Craton cleared the Coastal Plains of Mozambique to a position east of the Mozambique Fracture Zone. The southern Astrid Ridge is interpreted to consist of oceanic crust, also formed during this first stage, prior to the Riiser-Larsen Sea. During the second stage, Antarctica moved southward with respect to Africa forming the Mozambique Basin and the conjugate Riiser-Larsen Sea. The Mozambique Ridge and the Northern Natal Valley were formed at different spreading centres being active subsequently.

  5. Nitrogen-fixation Potential of Nodules in Four Types of Nitrogen-fixation Plants and Their Influencing Factors in Dry-hot Valley%干热河谷4种固氮植物根瘤固氮潜力及其影响因素

    Institute of Scientific and Technical Information of China (English)

    唐国勇; 李昆; 孙永玉; 张春华

    2012-01-01

    In addition to water, Nitrogen ( N) is often the key limiting factor for biological activity in Dry-hot Valleys, Biological N-fixation by nitrogen-fixation plants is of important source of N for vegetations in those areas. The nitrogenase activities (NAs) of nodules in Acacia auriliformis A. Cunn, Leucaena leucacephala (Lara. ) de Wit, Cajanus cajan ( L). Millspangh and Albiza kalkora Prain plantations were determined at the Dry red soils and Verti-sol spots at four different sampling times in a Dry-hot Valley with the acetylene reduction assay. The results showed that the NAs of nodules in L. leucacephala (16, 25 μmol·g -1·h-1 ) and A. auriliformis ( 15. 85μmol·g-1·h-1) were significantly higher than those in A. kalkora (9,60 μmol·g-1·h-1) and C. cajan (9.42 μmol·g-1h-1 )·The NAs of nodules in rainy season were significantly higher than those in dry season, and approximated 2. 3 times that in dry season. The NAs of nodules at the Dry red soils spots were 1.3 -1.6 times higher than those at the Vertisol spots. The research revealed besides plant type, the NAs of nodules were primarily affected by soil type, season and soil water content, but less affected by soil temperature.%氮是除水分之外影响干热河谷生物活性的关键因子,豆科植物生物固氮是该地区氮素的重要来源之一.采用乙炔还原法测定了干热河谷不同季节燥红土和变性土林地中大叶相思、新银合欢、木豆和山合欢根瘤固氮酶活性(NAs).结果表明:新银合欢(16.25 μmol · g-1·h-1)和大叶相思(15.85 μmol·g-1·h-1)根瘤NAs显著(P<0.001)高于山合欢(9.60 μmol·g-1·h-1)和木豆(9.42 μmol·g-1·h-1).雨季根瘤NAs显著高于旱季,约为旱季的2.3倍.燥红土样地上植物根瘤NAs是变性土样地的1.3~1.6倍.研究揭示:除植被类型外,干热河谷植物根瘤NAs主要受土壤类型、季节和土壤含水量的影响,而受土壤温度的影响较小.

  6. 元江干热河谷牛角瓜种质资源调查及果实性状的多元统计分析%Investigation on germplasm resources and multivariate statistical analysis on fruit characters ofCalotropis gigantea in Yuanjiang dry-hot valley in Yunnan

    Institute of Scientific and Technical Information of China (English)

    郑元; 高柱; 罗明灿; 刘鹏; 黄北; 唐军荣; 王连春; 马焕成; 刘惠民

    2015-01-01

    对元江干热河谷区29个牛角瓜种质资源地点进行实地调查,并对收集的不同种源牛角瓜的18个果实性状进行了相关分析、变异度分析、主成分分析、方差分析、聚类分析。结果表明:该区大量分布的野生牛角瓜种质资源具有丰富的多样性;牛角瓜果实的单果长、单果宽、单果高、单果鲜质量、果壳鲜质量这5个指标相互之间均呈极显著正相关,果实各组分的含水量与单果干质量的相关性高于单果鲜质量,果实长度、果实干质量、种子干质量是影响单果棉干质量与出棉率这2个重要棉纺指标的关键因子;果实性状指标的变异度范围在3.99%~42.84%之间,表明调查区内牛角瓜果实在不同种源之间存在广泛的遗传变异性;筛选出单果长、单果干质量、单果棉干质量、单果含水量、芯含水量、种子含水量、单果种子数、出棉率为牛角瓜的主要果实性状指标;筛选出GJ05、HH01、HH06、GJ02、GJ04、JS03为元江干热河谷区牛角瓜不同种源地点的优良单株,表现为果实品质性状与棉纺经济性状均较高,确定红河、个旧为元江干热河谷区牛角瓜不同地理分布的优良种源。%Twenty-nine germplasm resource sites ofCalotropis gigantea in Yuanjiang dry-hot valley were surveyed in theifeld, and eighteen fruit characters of collected fruits from different provenances were analyzed in multivariables, which including correlation analysis, variation analysis, principal component analysis, variance analysis, and cluster analysis. The results show that the large numbers of germplasm resources of wildC. gigantea in the distribution areas had abundant diversities; There were signiifcantly positive correlations among fruit length, fruit width, fruit height, fruit fresh weight, and shell fresh weight ofCalotropis gigantea; Fruit dry weight had higher correlation with the water content of each fruit component than

  7. Space analogue studies in Antarctica

    Science.gov (United States)

    Lugg, D.; Shepanek, M.

    1999-01-01

    Medical research has been carried out on the Australian National Antarctic Research Expeditions (ANARE) for 50 years. As an extension of this program collaborative Australian/United States research on immunology, microbiology, psychology and remote medicine has produced important data and insight on how humans adapt to the stress of extreme isolation, confinement and the harsh environment of Antarctica. An outstanding analogue for the isolation and confinement of space missions (especially planetary outposts), ANARE has been used as an international research platform by Australia and the United States since 1993. Collaborative research has demonstrated a lowered responsiveness of the immune system under the isolation and confinement of Antarctic winter-over; a reduction of almost 50% in T cell proliferation to mitogen phytohaemogglutinin, as well as changes in latent herpesvirus states and the expansion of the polyclonal latent Epstein-Barr virus infected B cell populations. Although no clinically significant disease has been found to result from these immune changes, research is currently assessing the effects of psychological factors on the immune system. This and associated research performed to date and its relevance to both organisations is discussed, and comment made on possible extensions to the program in both medical and other fields.

  8. Space analogue studies in Antarctica

    Science.gov (United States)

    Lugg, D.; Shepanek, M.

    1999-01-01

    Medical research has been carried out on the Australian National Antarctic Research Expeditions (ANARE) for 50 years. As an extension of this program collaborative Australian/United States research on immunology, microbiology, psychology and remote medicine has produced important data and insight on how humans adapt to the stress of extreme isolation, confinement and the harsh environment of Antarctica. An outstanding analogue for the isolation and confinement of space missions (especially planetary outposts), ANARE has been used as an international research platform by Australia and the United States since 1993. Collaborative research has demonstrated a lowered responsiveness of the immune system under the isolation and confinement of Antarctic winter-over; a reduction of almost 50% in T cell proliferation to mitogen phytohaemogglutinin, as well as changes in latent herpesvirus states and the expansion of the polyclonal latent Epstein-Barr virus infected B cell populations. Although no clinically significant disease has been found to result from these immune changes, research is currently assessing the effects of psychological factors on the immune system. This and associated research performed to date and its relevance to both organisations is discussed, and comment made on possible extensions to the program in both medical and other fields.

  9. Dry Etching

    DEFF Research Database (Denmark)

    Stamate, Eugen; Yeom, Geun Young

    2016-01-01

    Production of large-area flat panel displays (FPDs) involves several pattern transfer and device fabrication steps that can be performed with dry etching technologies. Even though the dry etching using capacitively coupled plasma is generally used to maintain high etch uniformity, due to the need...... for the higher processing rates in FPDs, high-density plasma processing tools that can handle larger-area substrate uniformly are more intensively studied especially for the dry etching of polysilicon thin films. In the case of FPD processing, the current substrate size ranges from 730 × 920 mm (fourth...... generation) to 2,200 × 2,500 mm (eighth generation), and the substrate size is expected to increase further within a few years. This chapter aims to present relevant details on dry etching including the phenomenology, materials to be etched with the different recipes, plasma sources fulfilling the dry...

  10. Haemoragisk Rift Valley Fever

    DEFF Research Database (Denmark)

    Fabiansen, Christian; Thybo, Søren

    2007-01-01

    A case of fatal hemorrhagic Rift Valley fever during an epidemic in Kenya's North Eastern Province in January 2007 is described.......A case of fatal hemorrhagic Rift Valley fever during an epidemic in Kenya's North Eastern Province in January 2007 is described....

  11. 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...

  12. 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.

  13. Application of a Regional Model to Astronomical Site Testing in Western Antarctica

    CERN Document Server

    Falvey, Mark

    2016-01-01

    The quality of ground based astronomical observations are significantly affected by telluric conditions, and the search for best sites has led to the construction of observatories at remote locations, including recent initiatives on the high plateaus of E Antarctica where the calm, dry and cloud free conditions during winter are recognized as amongst the best. Site selection is an important phase of any observatory development project, and candidate sites must be tested with specialized equipment, a process both time consuming and costly. A potential screening of site locations before embarking on field testing is through the use of climate models. Here, we describe the application of the Polar version of the Weather Research and Forecast (WRF) model to the preliminary site suitability assessment of an unstudied region in W Antarctica. Numerical simulations with WRF were carried out for the winter of 2011 at 3 km and 1 km spatial resolution over a region centered on the Ellsworth mountain range. Comparison wi...

  14. The Landsat Image Mosaic of Antarctica (LIMA): A Cutting-Edge Way for Students and Teachers to Learn about Antarctica

    Science.gov (United States)

    Campbell, Brian; Bindschadler, Robert

    2009-01-01

    By studying Antarctica via satellite and through ground-truthing research, we can learn where the ice is melting and why. The Landsat Image Mosaic of Antarctica (LIMA), a new and cutting-edge way for scientists, researchers, educators, students, and the public to look at Antarctica, supports this research and allows for unprecedented views of our…

  15. Cryptoendolithic lichen and cyanobacterial communities of the Ross Desert, Antarctica

    Science.gov (United States)

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

    1988-01-01

    Cryptoendolithic microbial communities in the Ross Desert (McMurdo Dry Valleys) are characterized on the basis of photosynthetic microorganisms and fungi. Two eukaryotic communities (the lichen-dominated and Hemichloris communities) and three cyanobacterial communities (the red Gloeocapsa, Hormathonema-Gloeocapsa, and Chroococcidiopsis communities) are described. Eleven coccoid, one pleurocapsoid, and five filamentous cyanobacteria occurring in these communities are characterized and illustrated. The moisture grade of the rock substrate seems to affect pH, formation of primary iron stain, and the distribution of microbial communities.

  16. Groundwater quality in the Santa Clara River Valley, California

    Science.gov (United States)

    Burton, Carmen A.; Landon, Matthew K.; Belitz, Kenneth

    2011-01-01

    The Santa Clara River Valley (SCRV) study unit is located in Los Angeles and Ventura Counties, California, and is bounded by the Santa Monica, San Gabriel, Topatopa, and Santa Ynez Mountains, and the Pacific Ocean. The 460-square-mile study unit includes eight groundwater basins: Ojai Valley, Upper Ojai Valley, Ventura River Valley, Santa Clara River Valley, Pleasant Valley, Arroyo Santa Rosa Valley, Las Posas Valley, and Simi Valley (California Department of Water Resources, 2003; Montrella and Belitz, 2009). The SCRV study unit has hot, dry summers and cool, moist winters. Average annual rainfall ranges from 12 to 28 inches. The study unit is drained by the Ventura and Santa Clara Rivers, and Calleguas Creek. The primary aquifer system in the Ventura River Valley, Ojai Valley, Upper Ojai Valley, and Simi Valley basins is largely unconfined alluvium. The primary aquifer system in the remaining groundwater basins mainly consists of unconfined sands and gravels in the upper portion and partially confined marine and nonmarine deposits in the lower portion. The primary aquifer system in the SCRV study unit is defined as those parts of the aquifers corresponding to the perforated intervals of wells listed in the California Department of Public Health (CDPH) database. Public-supply wells typically are completed in the primary aquifer system to depths of 200 to 1,100 feet below land surface (bls). The wells contain solid casing reaching from the land surface to a depth of about 60-700 feet, and are perforated below the solid casing to allow water into the well. Water quality in the primary aquifer system may differ from the water in the shallower and deeper parts of the aquifer. Land use in the study unit is approximately 40 percent (%) natural (primarily shrubs, grassland, and wetlands), 37% agricultural, and 23% urban. The primary crops are citrus, avocados, alfalfa, pasture, strawberries, and dry beans. The largest urban areas in the study unit are the cities of

  17. Acting Antarctica: science on stage

    Science.gov (United States)

    Ciceri, Piera; Tizzoni, Paola; Pierro, Luigia

    2016-04-01

    Key-words: Polar science, Earth science, Theatre, Hands on activities The legendary Antarctic Expedition of sir E. Shackleton and his crew of 27 aboard the Endurance (1914/16) trapped in the Antarctic ice has become the starting point to learn about Polar Science and Climate Change. While the students were involved into this incredible adventure by the astonishing images of the Australian photographer Frank Hurley (who joined the crew), they discovered the world in which this story happened. Students were then involved in hands-on activities and role plays and have become the writers of the play "Uomini a scienza ai confini del mondo". They act the story of Shackelton's expedition and they tell at the same time to the audience about ice pack, ice cores and their role in understanding the past of the climate, physical and geographical characteristic of polar regions, thermal phenomena related to adaptations of polar animals, solar radiation at different latitude, day/night duration. The theater was the place to "stage" some scientific experiments and to explain the current research carried out in polar regions and their importance in climate change studies and to stress some similarities between Antarctica and space. The project was carried out from teachers of science, letters and geography and was born in collaboration with the "Piccolo Teatro di Milano" and the association "Science Under 18" with the support of a professional actor and director and was played for other schools at "EXPO 2015" in Milano (Italy). In our opinion drama activities improve reading comprehension, and both verbal and non-verbal communication skills. To be able to write and to act, students need a deep understanding of contents. Arts, including theatre, are a good key to involve emotionally students. To have an audience different from their own teachers and classmates offers a real task and the opportunity to play and let grow real skills.

  18. Environmental and climate changes in Antarctica in the Geological Past

    Directory of Open Access Journals (Sweden)

    G. L. Leitchenkov

    2014-01-01

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

  19. VEGETATION DYNAMICS IN THE DRY VALLEYS OF YUNNAN, CHINA, DURING THE LAST 150 YEARS: IMPLICATIONS FOR ECOLOGICAL RESTORATION%云南干旱河谷150年来的植被变化研究及其对生态恢复的意义

    Institute of Scientific and Technical Information of China (English)

    MOSELEY Robert K; 唐亚

    2006-01-01

    在中国西南有许多关于过去环境及其变化原因的观点,但这些观点缺乏直接证据的支持,这在关于西南干旱河谷生态系统方面最为典型,而且目前干旱河谷地区的生物多样性保护和生态恢复计划主要都是基于这些主观的认识而不是科学的理解.该文的目的是通过对干旱河谷环境变化的描述及其诠释,提供干旱河谷的一个历史面貌,用以验证是否支持当前对于干旱河谷环境变化的认识和理解,该文研究的干旱河谷范围包括滇西北及其临近的四川和西藏. 28份1868~1949年间刊行的出版物中有关研究地区干旱河谷植被的历史资料和56幅清晰反映干旱河谷植被范围和状况的照片形成研究这种变化的历史基础,通过与2001~2005 年间相同地区和范围的植被现状以及56幅与上述照片取景完全相同的重复照片的比较,研究了干旱河谷植被的变化.研究结果发现,在过去约150 年间,研究地区的干旱河谷植被范围并没有显著的变化,在垂直方向没有向较高海拔扩展;耕地面积减少;滑坡主要是由当地本身的地质不稳定性和基础设施建设活动引起的.1868~2005年间文献资料和重复景观照片的对比研究,并不支持国内外许多有关干旱河谷环境退化的看法和观点以及以造林为主的干旱河谷生态恢复策略.%In southwestern China, there are many opinions about past environmental conditions and the historical drivers of change, but little direct evidence. Such is the case in Dry Valley ecosystems, where current conservation programs appear to be based more on subjective perceptions than scientific understanding. Our research objective was to develop an historical profile-the description and explanation of environmental change-for the Dry Valleys to see if today's perceptions about past change are supported by data. Our study area encompassed northwestern Yunnan and adjacent Sichuan and Tibet

  20. 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

  1. ULF fluctuations at Terra Nova Bay (Antarctica

    Directory of Open Access Journals (Sweden)

    A. Meloni

    2000-06-01

    Full Text Available ULF geomagnetic field measurements in Antarctica are a very important tool for better understanding the dynamics of the Earth’s magnetosphere and its response to the variable solar wind conditions. We review the results obtained in the last few years at the Italian observatory at Terra Nova Bay

  2. Antarctica: Is It More Than Just Ice?

    Science.gov (United States)

    Johnson, Cheryl; Gutierrez, Melida

    2009-01-01

    The authors introduced polar science in a fourth-grade classroom by means of 3 hands-on activities that addressed (1) the melting of glaciers and ice, (2) the differences between the North and the South Pole, and (3) the geography and landforms of Antarctica. An assessment 4 months after the original activity showed that students remembered the…

  3. Antarctica: Is It More Than Just Ice?

    Science.gov (United States)

    Johnson, Cheryl; Gutierrez, Melida

    2009-01-01

    The authors introduced polar science in a fourth-grade classroom by means of 3 hands-on activities that addressed (1) the melting of glaciers and ice, (2) the differences between the North and the South Pole, and (3) the geography and landforms of Antarctica. An assessment 4 months after the original activity showed that students remembered the…

  4. First airborne transient em survey in antarctica

    DEFF Research Database (Denmark)

    Auken, Esben; Mikucki, J. J.; Sørensen, Kurt Ingvard K.I.

    2012-01-01

    A first airborne transient electromagnetic survey was flown in Antarctica in December 2011 with the SkyTEM system. This transient airborne EM system has been optimized in Denmark for almost ten years and was specially designed for ground water mapping. The SkyTEM tool is ideal for mapping...

  5. Read--and Walk--to Antarctica

    Science.gov (United States)

    Harr, Natalie; Doneyko, Kathleen; Lee, Richard E., Jr.

    2012-01-01

    The students at Crestwood Primary School proved that they have what it takes to exercise their bodies and their minds. In an effort to support their teacher's scientific expedition to Antarctica, students from kindergarten to second grade pledged to read books and do physical activity that equated to the 12,900 km (8,000-mile) journey to the…

  6. Ostracoda from Vestfold Hill lake terraces, Antarctica

    Digital Repository Service at National Institute of Oceanography (India)

    Setty, M.G.A.P.

    Six species of ostracodes are recorded from two transects of terraces of Deep Lake, Vestfold Hills, Antarctica. Two species (@iXesteleberis@@ sp. and @iBradleya dictyon@@) range from Cretaceous to Recent, @iPoseidonamicus aff. P. major@@ ranges from...

  7. Climate controls on valley fever incidence in Kern County, California

    Science.gov (United States)

    Zender, Charles S.; Talamantes, Jorge

    2006-01-01

    Coccidiodomycosis (valley fever) is a systemic infection caused by inhalation of airborne spores from Coccidioides immitis, a soil-dwelling fungus found in the southwestern United States, parts of Mexico, and Central and South America. Dust storms help disperse C. immitis so risk factors for valley fever include conditions favorable for fungal growth (moist, warm soil) and for aeolian soil erosion (dry soil and strong winds). Here, we analyze and inter-compare the seasonal and inter-annual behavior of valley fever incidence and climate risk factors for the period 1980-2002 in Kern County, California, the US county with highest reported incidence. We find weak but statistically significant links between disease incidence and antecedent climate conditions. Precipitation anomalies 8 and 20 months antecedent explain only up to 4% of monthly variability in subsequent valley fever incidence during the 23 year period tested. This is consistent with previous studies suggesting that C. immitis tolerates hot, dry periods better than competing soil organisms and, as a result, thrives during wet periods following droughts. Furthermore, the relatively small correlation with climate suggests that the causes of valley fever in Kern County could be largely anthropogenic. Seasonal climate predictors of valley fever in Kern County are similar to, but much weaker than, those in Arizona, where previous studies find precipitation explains up to 75% of incidence. Causes for this discrepancy are not yet understood. Higher resolution temporal and spatial monitoring of soil conditions could improve our understanding of climatic antecedents of severe epidemics.

  8. Analysis of mercury and other heavy metals accumulated in lichen Usnea antarctica from James Ross Island, Antarctica.

    Science.gov (United States)

    Zvěřina, Ondřej; Láska, Kamil; Cervenka, Rostislav; Kuta, Jan; Coufalík, Pavel; Komárek, Josef

    2014-12-01

    The study was designed to investigate the content and distribution of selected heavy metals (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Fe, Pb and Zn) in samples of fruticose macrolichen Usnea antarctica from James Ross Island. A special emphasis was devoted to mercury and its species (elemental mercury and methylmercury). It was found that mercury contents were relatively high (up to 2.73 mg kg(-1) dry weight) compared to other parts of the Antarctic Peninsula region, while the concentrations of most other elements were within reported ranges. Mercury contents in lichens originating from the interior were higher than those from the coast, which is probably the result of local microclimate conditions. Similar trends were observed for Hg(0) and MeHg(+), whose contents were up to 0.14 and 0.098 mg kg(-1) dry weight, respectively. While mercury did not show a significant correlation with any other element, the mutual correlation of some litophile elements probably refers to the influence on thalli of resuspended weathered material. The influence of habitat and environmental conditions could play an essential role in the bioaccumulation of contaminants rather than just the simple presence of sources. Thus, the study of the thalli of this species can bring a new perspective on the interpretation of contaminant accumulation in lichens of the polar region.

  9. 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.

  10. Purge at West Valley

    Science.gov (United States)

    Mack, Warren

    1977-01-01

    Tells how the adviser of the student newspaper at West Valley College (Saratoga, California) was dismissed after the newspaper published stories based on investigations into alleged wrongdoings by administration members. (GW)

  11. 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 ...

  12. Shallow Groundwater and Brine Processes in Antarctica: Linking Seasonal and Interannual Changes in Active Layer Hydrology to Ecosystem Change and Thermokarst Formation

    Science.gov (United States)

    Levy, J. S.

    2015-12-01

    We report on measurements of soil hydrological and thermal properties from the McMurdo Dry Valleys of Antarctica (MDV), and relate them to changes in the spatial patterns of shallow groundwater flow (water tracks), landscape subsidence (thermokarst), and microbial and invertebrate ecosystem response. We show that shallow groundwater in the MDV is primarily derived from snowfall and seasonal ground ice melt, but is evaporatively concentrated during the summer flow period to produce saline to hypersaline active layer solutions. Multi-year profiles of soil temperature and soil moisture indicate that water track flow is largely limited to the duration of active layer conditions (~2 months) and that water track discharge is characterized by an early season pulse as ground ice melts, and a late season pulse as solutions flowing downslope accumulate at the base of the water tracks. Evaporative concentration of water track fluids, coupled with soil salt dissolution, and/or cation exchange reactions, result in enrichment of water track fluids in chloride and sulfate salts (depending on local soil chemistry) such that initially fresh snowmelt becomes saline to hypersaline over several km of groundwater flow. These brines shape soil ecosystems in the MDV by controlling salinity-dependent habitat suitability for invertebrates and microbial organisms. We show that these soil salts and shallow groundwater solutions accumulate in local depressions to form ponds, and that where these ponds are located above buried ice, the presence of salts leads to expansion of the basins to form large thermokarst depressions. Because water tracks are primarily snow-fed, and are moderated by shallow groundwater processes, they represent a component of the Antarctic hydrological system that is likely to respond rapidly to regional changes in temperature and precipitation, altering Antarctic terrestrial ecosystems, carbon budgets, and ground ice distribution.

  13. Dry Mouth

    Science.gov (United States)

    ... Use a fluoride rinse or brush-on fluoride gel before bedtime. See your dentist at least twice yearly to have your teeth examined and plaque removed, to help prevent tooth decay. Several herbal remedies have been used historically to treat dry ...

  14. The oldest plesiosaur (Reptilia, Sauropterygia from Antarctica

    Directory of Open Access Journals (Sweden)

    Alexander Wilhelm Armin Kellner

    2011-06-01

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

  15. 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.

  16. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Causes of Dry Eye Dry Eye Treatment What Is Dry Eye? Written By: Kierstan Boyd Reviewed By: ... your eyes do not produce enough tears, it is called dry eye. Dry eye is also when ...

  17. Crustal formation and evolution processes in the Natal Valley and Mozambique Ridge, off South Africa

    Science.gov (United States)

    Hanyu, Tomoko; Nogi, Yoshifumi; Fujii, Masakazu

    2017-09-01

    The evolution of seafloor spreading of Africa, South America, and Antarctica is key to understanding the initial break-up of Gondwana. Vector geomagnetic surveys were conducted in the Natal Valley and Mozambique Ridge, off South Africa. We summarize the nature of the crust using the results of dense vector geomagnetic anomaly data, as well as satellite gravity data. Based on both inversion and forward analytical results, we identified areas of stretched continental crust, with basaltic magma intrusion in parts, as the northern Natal Valley, north part of the Mozambique Ridge, and north part of the southern Natal Valley. Oceanic crust was identified in the south part of the southern Natal Valley and south part of the Mozambique Ridge. Magnetic isochrons M0-M10 were identified in the south part of the southern Natal Valley. Clear magnetic lineations were observed in the south part of the Mozambique Ridge, where some areas were distorted by hotspot volcanism. The location of the continental ocean boundary in the Natal Valley, along with a four-stage model of tectonic evolution of the study area since about 183 Ma, are newly proposed.

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

    Science.gov (United States)

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

    2013-12-01

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

  19. Constraining the recent history of the perennially ice-covered Lake Bonney, East Antarctica using He, Kr and Xe concentrations

    Science.gov (United States)

    Hall, Chris M.; Castro, Maria Clara; Kenig, Fabien; Doran, Peter T.

    2017-07-01

    Lake Bonney is a perennially ice-covered lake in the McMurdo Dry Valleys (MDVs) that has long been studied in order to provide constraints on the paleoclimate of West Antarctica. The lake is divided into two lobes, West Lake Bonney (WLB) and East Lake Bonney (ELB) that are separated by a narrow ridge. The two lobes currently receive surface melt water during austral summers from glacier-fed ephemeral streams and this meltwater enters the lake via a narrow ring, or moat, of liquid water that forms around the lake during summer. The West Lobe also receives water from direct input of melt water from Taylor glacier and saline water from irregular subglacial discharge. Here, we combine previously published He data from Lake Bonney with new Kr and Xe concentration data to examine the signatures of water recharge via the seasonal moat and these data are used to constrain a model for He, Kr and Xe transport within both WLB and ELB over about the last 5000-6000 yrs. A detailed numerical simulation is presented that combines diffusive transport of noble gases within the stratified water column of Lake Bonney, along with ice ablation at the top of the ice cover, partitioning of noble gases between water and ice, plus exchange of noble gases between WLB and ELB. Results strongly suggest that open moats have only operated for about 2-3 centuries within the last millennium. These results are corroborated by the high concentration of He, especially within WLB, which points to a history of ice cover with no open moats operating for both lobes for at least about 5 millennia. In addition, the distribution of He, Kr and Xe suggest that a significant rise of the water level of Lake Bonney associated with a warmer period may have been interrupted by a roughly 4-5 century long cold period during which the moats were not large enough to allow air saturated water into the lake, with this cold period ending about one century ago. In addition, during this cold period, there is evidence for

  20. Erosion-driven uplift in the Gamburtsev Subglacial Mountains of East Antarctica

    Science.gov (United States)

    Paxman, G. J. G.; Watts, A. B.; Ferraccioli, F.; Jordan, T. A.; Bell, R. E.; Jamieson, S. S. R.; Finn, C. A.

    2016-10-01

    The relative roles of climate and tectonics in mountain building have been widely debated. Central to this debate is the process of flexural uplift in response to valley incision. Here we quantify this process in the Gamburtsev Subglacial Mountains, a paradoxical tectonic feature in cratonic East Antarctica. Previous studies indicate that rifting and strike-slip tectonics may have provided a key trigger for the initial uplift of the Gamburtsevs, but the contribution of more recent valley incision remains to be quantified. Inverse spectral (free-air admittance and Bouguer coherence) methods indicate that, unusually for continents, the coherence between free-air gravity anomalies and bedrock topography is high (>0.5) and that the elastic thickness of the lithosphere is anomalously low (erosion are quantified: dendritic fluvial incision overprinted by Alpine-style glacial erosion in the Gamburtsevs and outlet glacier-type selective linear erosion in the Lambert Rift, part of the East Antarctic Rift System. 3D flexural models indicate that valley incision has contributed ca. 500 m of peak uplift in the Gamburtsevs and up to 1.2 km in the Lambert Rift, which is consistent with the present-day elevation of Oligocene-Miocene glaciomarine sediments. Overall, we find that 17-25% of Gamburtsev peak uplift can be explained by erosional unloading. These relatively low values are typical of temperate mountain ranges, suggesting that most of the valley incision in the Gamburtsevs occurred prior to widespread glaciation at 34 Ma. The pre-incision topography of the Gamburtsevs lies at 2-2.5 km above sea-level, confirming that they were a key inception point for the development of the East Antarctic Ice Sheet. Tectonic and/or dynamic processes were therefore responsible for ca. 80% of the elevation of the modern Gamburtsev Subglacial Mountains.

  1. Surface ozone characterization at Larsemann Hills and Maitri, Antarctica.

    Science.gov (United States)

    Ali, Kaushar; Trivedi, D K; Sahu, S K

    2017-04-15

    Data are analyzed in terms of daily average ozone, its diurnal variation and its relation with meteorological parameters like dry bulb temperature (T), wet bulb temperature (Tw), atmospheric pressure and wind speed based on measurement of these parameters at two Indian Antarctic stations (Larsemann Hills, and Maitri) during 28th Indian Scientific Expedition of Antarctica (ISEA) organized during Antarctic summer of the year 2008-09. The work has been carried out to investigate summer time ozone level and its day-to-day and diurnal variability at these coastal locations and to highlight possible mechanism of ozone production and destruction. The result of the analysis indicates that daily average ozone concentration at Larsemann Hills varied from ~13 and ~20ppb with overall average value of ~16ppb and at Maitri, it varied from ~16 and ~21ppb with overall average value of ~18ppb. Photochemistry is found to partially contribute occasionally to the surface layer ozone at both the stations. Lower concentration of ozone at Maitri during beginning of the observational days may be due to destruction of ozone through activated halogens, whereas higher ozone on latter days may be due to photochemistry and advective transport from east to south-east areas. Ozone concentration during blizzard episodes at both the stations is reduced due to slow photochemical production of ozone, its photochemical removal and removal through deposition of ozone molecules on precipitation particles. Diurnal variation of ozone at Larsemann Hills and Maitri has been found to be absent.

  2. Radiocarbon analyses along the EDML ice core in Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Wal, R.S.W. van de; Veen, C. van der [Utrecht Univ. (Netherlands). Inst. for Marine and Atmospheric research; Meijer, H.A.J.; De Rooij, M. [Univ. of Groningen (Netherlands). Center for Isotope Research

    2007-02-15

    Samples, 17 in total, from the EDML core drilled at Kohnen station Antarctica are analysed for {sup 14}CO and {sup 14}CO{sub 2} with a dry-extraction technique in combination with accelerator mass spectrometry. Results of the in situ produced {sup 14}CO fraction show a very low concentration of in situ produced {sup 14}CO. Despite these low levels in carbon monoxide, a significant in situ production is observed in the carbon dioxide fraction. For the first time we found background values for the ice samples which are equal to line blanks. The data set is used to test a model for the production of {sup 14}C in the ice matrix, in combination with a degassing as {sup 14}CO{sub 2} and possibly as {sup 14}CO into the air bubbles. Application of the model, for which no independent validation is yet possible, offers the opportunity to use radiocarbon analysis as dating technique for the air bubbles in the ice. Assigning an arbitrary error of 25% to the calculation of the in situ production leads to age estimates, after correction for the in situ production, which are in agreement with age estimates based on a volcanic layer match of EDML to the Dome C timescale in combination with a correction for firn diffusion.

  3. Nitrogen form influences the response of Deschampsia antarctica to dark septate root endophytes.

    Science.gov (United States)

    Upson, Rebecca; Read, David J; Newsham, Kevin K

    2009-11-01

    Fungi with dematiaceous septate hyphae, termed dark septate endophytes (DSE), are common in plant roots, particularly in cold-stressed habitats, but their effects on their host plants remain obscure. Here, we report a study that assessed the effects of six DSE on the growth and nutrient balance of Deschampsia antarctica when plants were supplied with the same amount of nitrogen in organic (casein hydrolysate) or inorganic (ammonium sulphate) form under controlled conditions. After 60 days, the DSE, that had each been isolated from D. antarctica and which analyses of internal transcribed spacer and large subunit regions indicated were similar to members of the Helotiales (Oculimacula yallundae, Mollisia and Tapesia spp.) and unassigned anamorphic ascomycetes, typically had no effect on, or reduced by 33-71%, shoot and root dry weights relative to uninoculated controls when plants had been supplied with nitrogen in inorganic form. In contrast, the DSE usually enhanced shoot and root dry weights by 51-247% when plants had been supplied with organic nitrogen. In the presence of inorganic nitrogen, only sporadic effects of DSE were recorded on shoot and root nitrogen or phosphorus concentrations, whereas in the presence of organic nitrogen, three to six of the DSE isolates increased shoot and root nitrogen and phosphorus contents. Most of the isolates decreased the phosphorus concentrations of shoots and roots when plants had been supplied with nitrogen in organic form. Our data suggest that DSE are able to mineralise peptides and amino acids in the rhizosphere, making nitrogen more freely available to roots.

  4. 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.

  5. 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.

  6. Boyne Valley Tombs

    Science.gov (United States)

    Prendergast, Frank

    The passage tombs of the Boyne Valley exhibit the greatest level of development of the megalithic tomb building tradition in Ireland in terms of their morphology, embellishment, burial tradition, grave goods, clustering, and landscape siting. This section examines these characteristics and gives a summary archaeoastronomical appraisal of their orientation and detected astronomical alignment.

  7. Red (Planet) River Valleys

    Institute of Scientific and Technical Information of China (English)

    陈淑娴

    1995-01-01

    Mars today is a frozen desert,but the photos sent back by the Mariner and Viking probes in the 1970s indicate its past was less bleak and more Earth-like. The images showed sinuous channels and valleys that were al-

  8. Managing Human Activities in Antarctica : Should Wilderness Protection Count?

    NARCIS (Netherlands)

    Bastmeijer, C.J.

    2005-01-01

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

  9. Bringing Silicon Valley inside.

    Science.gov (United States)

    Hamel, G

    1999-01-01

    In 1998, Silicon Valley companies produced 41 IPOs, which by January 1999 had a combined market capitalization of $27 billion--that works out to $54,000 in new wealth creation per worker in a single year. Multiply the number of employees in your company by $54,000. Did your business create that much new wealth last year? Half that amount? It's not a group of geniuses generating such riches. It's a business model. In Silicon Valley, ideas, capital, and talent circulate freely, gathering into whatever combinations are most likely to generate innovation and wealth. Unlike most traditional companies, which spend their energy in resource allocation--a system designed to avoid failure--the Valley operates through resource attraction--a system that nurtures innovation. In a traditional company, people with innovative ideas must go hat in hand to the guardians of the old ideas for funding and for staff. But in Silicon Valley, a slew of venture capitalists vie to attract the best new ideas, infusing relatively small amounts of capital into a portfolio of ventures. And talent is free to go to the companies offering the most exhilarating work and the greatest potential rewards. It should actually be easier for large, traditional companies to set up similar markets for capital, ideas, and talent internally. After all, big companies often already have extensive capital, marketing, and distribution resources, and a first crack at the talent in their own ranks. And some of them are doing it. The choice is yours--you can do your best to make sure you never put a dollar of capital at risk, or you can tap into the kind of wealth that's being created every day in Silicon Valley.

  10. MARSSIM Landform Evolution Model: Hydrologic Constraints on the Noachian Early Dry Period

    Science.gov (United States)

    Boatwright, B. D.; Head, J. W.

    2017-10-01

    We propose to test several hydrologic parameters to constrain the nature of highland degradation on Noachian Mars. This early dry period is less well characterized than the terminal epoch of valley network formation.

  11. Dry tilt network at Mount Rainier, Washington

    Science.gov (United States)

    Dzurisin, Daniel; Johnson, Daniel J.; Symonds, R.B.

    1984-01-01

    In addition to its primary responsibility of monitoring active Mount St. Helens, the David A. Johnston Cascades Volcano Observatory (CVO) has been charged with obtaining baseline geodetic and geochemical information at each of the other potentially active Cascade volcanoes. Dry tilt and/or trilateration networks were established during 1975-82 at Mount Baker, Mount St. Helens, Mount Hood, Mount Shasta, Lassen Peak, Crater Lake, and Long Valley caldera; coverage was extended during September 1982 to include Mount Rainier.

  12. Benefit Analysis of Acacia suma Mixed Forest with Eucalyptus camaldulensis in Yuanmou Dry-Hot Valley%元谋干热河谷苏门答腊金合欢×赤桉混交林的效益分析

    Institute of Scientific and Technical Information of China (English)

    路卫华

    2015-01-01

    .In addition,the mixed forest model had a high degree of stability and realization of natural regeneration.The suggests that in the dry-hot valley areas popu-larization of Acacia suma mixed forests not only provide firewood,and non-timber products,and also has important practical significance for vegetation restoration,reconstruction.

  13. Dynamics and mass balance of Taylor Glacier, Antarctica: 3. State of mass balance

    Science.gov (United States)

    Kavanaugh, J. L.; Cuffey, K. M.; Morse, D. L.; Bliss, A. K.; Aciego, S. M.

    2009-11-01

    Taylor Glacier flows from the East Antarctic Ice Sheet and terminates in the McMurdo Dry Valleys, where it has left a geomorphologic record of past incursions. Here we use new data on the flow, thickness, and surface balance of Taylor Glacier to calculate ice fluxes and assess the current state of mass balance. Overall, the glacier is close to a state of zero net balance, and has largely adjusted to reduced snowfall on the Taylor Dome source region in the mid Holocene. One region of the upper ablation zone appears to be losing mass. Evidence from ice surface morphology and stable isotope profiles suggests that this mass loss is a long-term phenomenon, hence probably a lingering response to the earlier drying of Taylor Dome. Our data give a general indication of the size of ablation or accumulation changes needed for ice to advance far into Taylor Valley, as occurred 70 to 130 ka ago.

  14. The genus Bryoerythrophyllum (Musci, Pottiaceae in Antarctica

    Directory of Open Access Journals (Sweden)

    Sollman Philip

    2015-07-01

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

  15. Autonomous Observations in Antarctica with AMICA

    CERN Document Server

    Di Rico, Gianluca; Dolci, Mauro; Straniero, Oscar; Valentini, Angelo; Valentini, Gaetano; Di Cianno, Amico; Giuliani, Croce; Magrin, Demetrio; Bonoli, Carlotta; Bortoletto, Favio; D'Alessandro, Maurizio; Corcione, Leonardo; Riva, Alberto

    2010-01-01

    The Antarctic Multiband Infrared Camera (AMICA) is a double channel camera operating in the 2-28 micron infrared domain (KLMNQ bands) that will allow to characterize and exploit the exceptional advantages for Astronomy, expected from Dome C in Antarctica. The development of the camera control system is at its final stage. After the investigation of appropriate solutions against the critical environment, a reliable instrumentation has been developed. It is currently being integrated and tested to ensure the correct execution of automatic operations. Once it will be mounted on the International Robotic Antarctic Infrared Telescope (IRAIT), AMICA and its equipment will contribute to the accomplishment of a fully autonomous observatory.

  16. Antarctica and the strategic plan for biodiversity.

    Science.gov (United States)

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

    2017-03-01

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

  17. Antarctica: measuring glacier velocity from satellite images.

    Science.gov (United States)

    Lucchitta, B K; Ferguson, H M

    1986-11-28

    Many Landsat images of Antarctica show distinctive flow and crevasse features in the floating part of ice streams and outlet glaciers immediately below their grounding zones. Some of the features, which move with the glacier or ice stream, remain visible over many years and thus allow time-lapse measurements of ice velocities. Measurements taken from Landsat images of features on Byrd Glacier agree well with detailed ground and aerial observations. The satellite-image technique thus offers a rapid and cost-effective method of obtaining average velocities, to a first order of accuracy, of many ice streams and outlet glaciers near their termini.

  18. Exhumation of the Shackleton Range, Antarctica

    Science.gov (United States)

    Lucka, Nicole; Lisker, Frank; Läufer, Andreas; Spiegel, Cornelia

    2013-04-01

    The Shackleton Range is situated between 80° - 81°S and 19° - 31°W, where it forms the continuation of the Transantarctic Mountains in the Weddell Sea sector of Antarctica. There, Precambrian igneous and metamorphic basement is overlain by (meta-) sedimentary rocks of an Early Paleozoic nappe stack and post-orogenic red beds. Nappe stacking resulted from the collision of East and West Gondwana due to the closure of the Mozambique Ocean in pan-African times. The uplift and exhumation history of the Shackleton Range has been analysed earlier based on a series of vertical fission track profiles (Schäfer, 1998; Lisker et al., 1999). Zircon ages range from ~160 to 210 Ma while apatite ages between ~95 and ~170 Ma comprise a break in slope of the altitude regression at ~110 Ma, and are accompanied by mean track lengths of 12.7 - 14.1 µm (standard deviation 1.0 - 1.4 µm). These data have been interpreted qualitatively in terms of two cooling/ exhumation stages during Jurassic and mid-Cretaceous times. However, the recognition of Jurassic volcaniclastic rocks associated with the ~180 Ma Ferrar event in the vicinity of the sample locations (Buggisch et al., 1994) challenges this exhumation concept. Moreover, new fission track proxy data (Dpar) and apatite (U-Th-Sm)/He ages between 88 and 171 Ma allow thermal history modelling of the combined thermochronological data. First tentative thermal history models suggest early Mesozoic cooling followed by (post-) Jurassic heating and final cooling since the Late Cretaceous. This scenario requires burial of the Shackleton Range region, and therefore the existence of a sedimentary basin at least during the Jurassic-Early Cretaceous, and subsequent basin inversion. The thickness of the now vanished sedimentary strata did unlikely exceed 2 - 3 km. Future work including additional apatite fission track analyses will help to quantifying geometry, depth and timing of this depocentre and evaluating potential links with the coeval

  19. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Eye Symptoms Causes of Dry Eye Dry Eye Treatment What Is Dry Eye? Written By: Kierstan Boyd ... your vision. Privacy Policy Related New Dry Eye Treatment is a Tear-Jerker Jul 21, 2017 Three ...

  20. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Español Eye Health / Eye Health A-Z Dry Eye Sections What Is Dry Eye? Dry Eye Symptoms ... Dry Eye Dry Eye Treatment What Is Dry Eye? Written By: Kierstan Boyd Reviewed By: Brenda Pagan- ...

  1. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Español Eye Health / Eye Health A-Z Dry Eye Sections What Is Dry Eye? Dry Eye Symptoms ... Dry Eye Dry Eye Treatment What Is Dry Eye? Leer en Español: ¿Qué Es el Ojo Seco? ...

  2. 干旱气候变化对西南干旱河谷农业的影响及适应性对策研究%The Impact of Arid Climate Change on Agriculture of Dry Valley in Southwest China and its Adaptive Countermeasures

    Institute of Scientific and Technical Information of China (English)

    鲍文

    2011-01-01

    在干旱气候变化情境下,西南干旱河谷生态环境的脆弱性和发展滞后,会进一步强化其农业不利的发展环境.为改变干旱河谷农业资源独特但利用粗放的现实,需妥善处理好资源开发与生态环境的关系,明确干旱河谷农业适应干旱气候变化的原则.最后提出发展现代草地畜牧业、加强特色农业与农业产业化建设、注重生态农业开发、构建现代农业节水技术推广体系、大力发展服务“三农”的第三产业和因地制宜地进行水利设施基础建设和可再生能源开发的西南干旱河谷农业适应性对策.%The eco-environmental vulnerability and underdevelopment of the agriculture in Southwest China would strengthen its disadvantage conditions further on the condition of arid climate change. It is necessary to deal with the relations between resource utilization and eco-envi-ronment finely and ascertain the adaptive principles on the dry valley agriculture to the arid climate change in order to change the extensive utilization of the special agricultural resources. The paper gave . Some suggestion on adaptive countermeasures that develop modern rangeland husbandry, strengthen the special agriculture and agricultural industrialization, emphasis on the ecological agriculture development, construct the extension system of water-saving modem agriculture, encourage the service industry related to "agriculture, peasants and the countryside" , construct water utilization facilities, and exploit the renewable energies.

  3. 干旱气候变化对西南干旱河谷农业的影响及适应性对策研究%The Impact of Arid Climate Change on Agriculture of Dry Valley in Southwest China and Its Adaptive Countermeasures

    Institute of Scientific and Technical Information of China (English)

    鲍文

    2011-01-01

    The eco-environmental vulnerability and underdevelopment of the agriculture in Southwest China would strengthen its disadvantage conditions further on the condition of arid climate change. It is necessary to deal with the relations between resource utilization and eco-environment finely and ascertain the adaptive principles on the dry valley agriculture to the arid climate change in order to change the extensive utilization of the special agricultural resources. The paper gave some adaptive countermeasures that develop modem rangeland husbandry, strengthening the special agriculture and agricultural industrialization, emphasis on the ecological agriculture development, constructing the extension system of water-saving modern agriculture, encouraging the service industry related to "agriculture, peasants and the countryside", constructing water utilization facilities, and exploiting the renewable energies.%在干旱气候变化情境下,西南干旱河谷生态环境的脆弱性和发展滞后,会进一步强化其农业不利的发展环境.为改变干旱河谷农业资源独特但利用粗放的现实,需妥善处理好资源开发与生态环境的关系,明确干旱河谷农业适应干旱气候变化的原则.文章最后提出发展现代草地畜牧业、加强特色农业与农业产业化建设、注重生态农业开发、构建现代农业节水技术推广体系、大力发展服务"三农"的第三产业和因地制宜,进行水利设施基础建设和可再生能源开发的西南干旱河谷农业适应性对策建议.

  4. Refuge in Belen Valley

    OpenAIRE

    Arias-Caballero, Diego Andres

    2013-01-01

    A story about love and desire to imagine architecture in a peruvian landscape. On one hand, 'Refuge in Belen Valley' is a thesis about discovering the ideal conditions that architecture should meet in a landscape, conditions that approach the idea of an offering of man rather than a conditioning for man. On the other, it is a thesis about thinking architecture as a composition derived out of material properties, emotional intentions, inhabiting possibilities and counterpoint, the arrangement ...

  5. Building China's Silicon Valley

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Ellis Rahhal and Andrew Schorr sit across from each other in the minimalist office of their tech startup,all clean lines and white linoleum floors.A pair of toothbrushes hint at many a late night hunched over their computers.Outside the window,the sun is slowly setting behind jagged mountains.The scene is classic Silicon Valley.But Rahhal and Schorr aren't in California.They're in suburban Beijing.

  6. Mississippi Alluvial Valley

    Science.gov (United States)

    Reinecke, K.J.; Kaminski, R.M.; Moorhead, D.J.; Hodges, J.D.; Nasser, J.R.; Smith, L.M.; Pederson, R.L.; Kaminski, R.M.

    1989-01-01

    Available data are summarized according to the following major topics: (1) characteristics of the Mississippi Alluvial Valley (MAV); (2) waterfowl populations associated with the MAV; (3) habitat requirements of migrating and wintering waterfowl in the MAV; (4) current habitat management practices in the MAV, including croplands, moist-soil impoundments, and forested wetlands; (5) status and classification of winter habitat in the MAV; and (6) research and management information needs.

  7. 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.

  8. Deglacial temperature history of West Antarctica

    Science.gov (United States)

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

    2016-12-01

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

  9. The Landsat Image Mosaic of Antarctica

    Science.gov (United States)

    Bindschadler, R.; Vornberger, P.; Fleming, A.; Fox, A.; Mullins, J.; Binnie, D.; Paulsen, S.J.; Granneman, B.; Gorodetzky, D.

    2008-01-01

    The Landsat Image Mosaic of Antarctica (LIMA) is the first true-color, high-spatial-resolution image of the seventh continent. It is constructed from nearly 1100 individually selected Landsat-7 ETM+ scenes. Each image was orthorectified and adjusted for geometric, sensor and illumination variations to a standardized, almost seamless surface reflectance product. Mosaicing to avoid clouds produced a high quality, nearly cloud-free benchmark data set of Antarctica for the International Polar Year from images collected primarily during 1999-2003. Multiple color composites and enhancements were generated to illustrate additional characteristics of the multispectral data including: the true appearance of the surface; discrimination between snow and bare ice; reflectance variations within bright snow; recovered reflectance values in regions of sensor saturation; and subtle topographic variations associated with ice flow. LIMA is viewable and individual scenes or user defined portions of the mosaic are downloadable at http://lima.usgs.gov. Educational materials associated with LIMA are available at http://lima.nasa.gov.

  10. Field Surveys, IOC Valleys. Volume III, Part I. Cultural Resources Survey, Dry Lake Valley, Nevada.

    Science.gov (United States)

    1981-08-01

    Artemisia nova) but also include cliffrose (Cowania mexicana ) and broom snakeweed (Gutierrezia sarothreae) as dominant species. Other species include... CULTURA Ale ~~REOUC SURVEYa AREASczCAvE L CU 11U CUUI 3-2 E-TR-48-III-I 69 was used because it is considered intensive by the Bureau of Land Management and

  11. Field Surveys, IOC Valleys. Biological Resources Survey, Dry Lake Valley, Nevada. Volume II, Part I.

    Science.gov (United States)

    1981-08-01

    members of the cactaceae family: Coryphantha vivipara, Echinocereus engelmannii, Sclerocactus pubispinus, Opuntia erinacea, Opuntia polycantha, and...Streptantnus cordatus ArFtemisia tr-identata Arem s p. Cactaceae Aster sp. Corypnantha vivipara* Baiy pleniradiata Ectinocereus engelmannii* c W -acis sp

  12. Optical manipulation of valley pseudospin

    Science.gov (United States)

    Ye, Ziliang; Sun, Dezheng; Heinz, Tony F.

    2017-01-01

    The coherent manipulation of spin and pseudospin underlies existing and emerging quantum technologies, including quantum communication and quantum computation. Valley polarization, associated with the occupancy of degenerate, but quantum mechanically distinct valleys in momentum space, closely resembles spin polarization and has been proposed as a pseudospin carrier for the future quantum electronics. Valley exciton polarization has been created in the transition metal dichalcogenide monolayers using excitation by circularly polarized light and has been detected both optically and electrically. In addition, the existence of coherence in the valley pseudospin has been identified experimentally. The manipulation of such valley coherence has, however, remained out of reach. Here we demonstrate all-optical control of the valley coherence by means of the pseudomagnetic field associated with the optical Stark effect. Using below-bandgap circularly polarized light, we rotate the valley exciton pseudospin in monolayer WSe2 on the femtosecond timescale. Both the direction and speed of the rotation can be manipulated optically by tuning the dynamic phase of excitons in opposite valleys. This study unveils the possibility of generation, manipulation, and detection of the valley pseudospin by coupling to photons.

  13. 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.

  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. Molecular variation of antarctic grass Deschampsia antarctica Desv. from King George Island (Antarctica

    Directory of Open Access Journals (Sweden)

    Katarzyna J. Chwedorzewska

    2011-01-01

    Full Text Available Deschampsia antarctica Desv. plants collected on King George Islands (Antarctica at two localities that differ in topographic and nutrition conditions exhibited morphological variation that differentiated plants of both locations. The molecular variation characteristic to individuals of both sites was tested using AFLP approach in order to verify whether morphological variation characteristic to the plants resulted from environmental factors or possibly from differences at the DNA level. Four primer pair combinations were used to generate 339 AFLP fragments, 132 of which were polymorphic and allowed evaluation of genetic relationships among D. antarctica individuals. Chi-square test revealed that only 12 signals were discriminative for the plants from both locations. Cluster analysis conducted on these AFLP fragments demonstrated that plants from the location rich in biogenes were more polymorphic than those from poor one. Our data suggest that the phenotypic variation specific to plants of both locations seem to be the result of adaptation to the environmental conditions like soil and moisture rather than reflect genetic differences.

  16. Land Subsidence Caused by Groundwater Exploitation in Quetta Valley, Pakistan

    Directory of Open Access Journals (Sweden)

    Najeebullah Kakar

    2016-12-01

    Full Text Available Land subsidence is affecting several metropolitan cities in developing as well as developed countries around the world such as Nagoya (Japan, Shanghai (China, Venice (Italy and San Joaquin valley (United States. This phenomenon is attributed to natural as well as anthropogenic activities that include extensive groundwater withdrawals. Quetta is the largest city of Balochistan province in Pakistan. This valley is mostly dry and ground water is the major source for domestic and agricultural consumption. The unplanned use of ground water resources has led to the deterioration of water quality and quantity in the Quetta valley. Water shortage in the region was further aggravated by the drought during (1998-2004 that hit the area forcing people to migrate from rural to urban areas. Refugees from the war torn neighboring Afghanistan also contributed to rapid increase in population of Quetta valley that has increased from 0.26 million in 1975 to 3.0 million in 2016. The objective of this study was to measure the land subsidence in Quetta valley and identify the effects of groundwater withdrawals on land subsidence. To achieve this goal, data from five Global Positioning System (GPS stations were acquired and processed. Furthermore the groundwater decline data from 41 observation wells during 2010 to 2015 were calculated and compared with the land deformation. The results of this study revealed that the land of Quetta valley is subsiding from 30mm/y on the flanks to 120 mm/y in the central part. 1.5-5.0 m/y of groundwater level drop was recorded in the area where the rate of subsidence is highest. So the extensive groundwater withdrawals in Quetta valley is considered to be the driving force behind land subsidence.

  17. 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

  18. NNSS Soils Monitoring: Plutonium Valley (CAU 366) FY2015

    Energy Technology Data Exchange (ETDEWEB)

    Nikolich, George [Desert Research Inst. (DRI), Las Vegas, NV (United States); Mizell, Steve [Desert Research Inst. (DRI), Las Vegas, NV (United States); McCurdy, Greg [Desert Research Inst. (DRI), Reno, NV (United States); Campbell, Scott [Desert Research Inst. (DRI), Las Vegas, NV (United States); Miller, Julianne J. [Desert Research Inst. (DRI), Las Vegas, NV (United States)

    2017-02-01

    Desert Research Institute (DRI) is conducting a field assessment of the potential for contaminated soil transport from the Plutonium Valley Contamination Area (CA) as a result of wind transport and storm runoff in support of National Nuclear Security Administration (NNSA) efforts to complete regulatory closure of the contamination areas. The DRI work is intended to confirm the likely mechanism(s) of transport and determine the meteorological conditions that might cause movement of contaminated soils. The emphasis of the work is on collecting sediment transported by channelized storm runoff at the Plutonium Valley investigation sites. These data will inform closure plans that are being developed, which will facilitate the appropriate closure design and post-closure monitoring. In 2011, DRI installed two meteorological monitoring stations south (station #1) and north (station #2) of the Plutonium Valley CA and a runoff sediment sampling station within the CA. Temperature, wind speed, wind direction, relative humidity, precipitation, solar radiation, barometric pressure, soil temperature, and airborne particulate concentration are collected at both meteorological stations. The maximum, minimum, and average or total (as appropriate) for each of these parameters are recorded for each 10-minute interval. The sediment sampling station includes an automatically activated ISCO sampling pump with collection bottles for suspended sediment, which is activated when sufficient flow is present in the channel, and passive traps for bedload material that is transported down the channel during runoff events. This report presents data collected from these stations during fiscal year (FY) 2015.

  19. 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.

  20. Environmental controls of marine productivity hot spots around Antarctica

    National Research Council Canada - National Science Library

    Arrigo, Kevin R; van Dijken, Gert L; Strong, Aaron L

    2015-01-01

    ...) in 46 coastal polynyas around Antarctica. Data presented here suggest that melting ice shelves are a primary supplier of Fe to coastal polynyas, with basal melt rates explaining 59% of the between...

  1. Antarctica and the strategic plan for biodiversity

    Science.gov (United States)

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

    2017-01-01

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

  2. Occurrence of organochlorine pesticides in the environmental matrices from King George Island, west Antarctica.

    Science.gov (United States)

    Zhang, Qinghua; Chen, Zhaojing; Li, Yingming; Wang, Pu; Zhu, Chaofei; Gao, Guanjun; Xiao, Ke; Sun, Huizhong; Zheng, Shucheng; Liang, Yong; Jiang, Guibin

    2015-11-01

    Antarctica is considered as a final sink of many persistent organic pollutants (POPs). This work aims to investigate the levels, distributions and potential sources of organochlorine pesticides (OCPs) with HRGC/HRMS technique. Twenty-three OCPs were measured in various environmental matrices from King George Island, west Antarctica. The total concentrations (Σ23OCPs) were at quite low levels, ranging 93.6-1260 pg g(-1) dry weight (dw) in soil and sediment, 223-1053 pg g(-1) dw in moss and 373-812 pg g(-1) dw in lichen. Hexachlorobenzene (HCB), dichloro-diphenyl-trichloroethane (DDT) and its metabolites (especially p,p'-DDE) and hexachlorocyclohexanes (HCHs) were the main contaminants in all samples. Lower α-HCH/γ-HCH and higher p,p'-DDE/p,p'-DDT ratios compared with the technical products indicated long-range atmospheric transport (LRAT) of recent lindane and aged technical DDT. Significant dependence of many OCPs concentrations on total organic carbon (TOC) was observed. Apart from LRAT, local biotic activities could also contribute and influence the spatial distribution of the contaminants.

  3. Oleaginous yeasts from Antarctica: Screening and preliminary approach on lipid accumulation.

    Science.gov (United States)

    Viñarta, Silvana C; Angelicola, M Virginia; Barros, J Maximiliano; Fernández, Pablo M; Mac Cormak, Walter; Aybar, Manuel J; de Figueroa, Lucía I C

    2016-12-01

    The capability of 17 Rhodotorula spp. isolated from Antarctica to accumulate intracellular lipids in nitrogen-limited medium was investigated. As results, 10 isolates were selected by Nile red staining, while 12 isolates were selected as oleaginous by analysis of total lipid content (20.4-73%, w/w of dry biomass). The higher lipid production and accumulation was exhibited for six strains belonging to three species of Rhodotorula (Rhodotorula glutinis, Rhodotorula glacialis, and Rhodotorula laryngis). This is the first report where R. laryngis have been identified within oleaginous specie. Lipid accumulation was evaluated comparatively in two nitrogen-limited glucose-based media (MI and MII). MI (low C/N ratio) was more suitable for biomass and lipid production while in MII (high C/N ratio) total lipid content was improved. R. glutinis R4, R. glacialis R15, and R. glutinis R48 showed high lipid concentrations (4.65-6.93 g L(-1) ) and they were able to accumulate large amounts of lipids per gram of biomass (47-77%, w/w). A similar profile in fatty acids composition and content of neutral lipids to vegetable oils was observed, indicating that lipids produced by oleaginous Antarctic yeasts can be considered an alternative feedstock for biodiesel production. Antarctica represents an important source of oleaginous yeasts with adaptive capabilities to accumulate considerable amounts of lipids with biotechnological interest at 15 °C and 25 °C.

  4. Caloplaca coeruleofrigida sp. nova, a species from continental Antarctica

    DEFF Research Database (Denmark)

    Søchting, Ulrik; Seppelt, R.

    2003-01-01

    Caloplaca coeruleofrigida Søchting & Seppelt is described from Southern Victoria Land, continental Antarctica. It is characterized by vertically elongated papillae and a pale orange pigmentation on shaded parts, and black thallus and apothecia on exposed parts of the thallus......Caloplaca coeruleofrigida Søchting & Seppelt is described from Southern Victoria Land, continental Antarctica. It is characterized by vertically elongated papillae and a pale orange pigmentation on shaded parts, and black thallus and apothecia on exposed parts of the thallus...

  5. Occurrence and Diversity of Marine Yeasts in Antarctica Environments

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xue; HUA Mingxia; SONG Chunli; CHI Zhenming

    2012-01-01

    A total of 28 yeast strains were obtained from the sea sediment of Antarctica.According to the results of routine identification and molecular characterization,the strains belonged to species of Yarrowia lipolytica,Debaryomyces hansenii,Rhodotorula slooffiae,Rhodotorula mucilaginosa,Sporidiobolus salmonicolor,Aureobasidium pullulans,Mrakia frigida and Guehomyces pullulans,respectively.The Antarctica yeasts have wide potential applications in biotechnology,for some of them can produce β-galactosidase and killer toxins.

  6. Occurrence and diversity of marine yeasts in Antarctica environments

    Science.gov (United States)

    Zhang, Xue; Hua, Mingxia; Song, Chunli; Chi, Zhenming

    2012-03-01

    A total of 28 yeast strains were obtained from the sea sediment of Antarctica. According to the results of routine identification and molecular characterization, the strains belonged to species of Yarrowia lipolytica, Debaryomyces hansenii, Rhodotorula slooffiae, Rhodotorula mucilaginosa, Sporidiobolus salmonicolor, Aureobasidium pullulans, Mrakia frigida and Guehomyces pullulans, respectively. The Antarctica yeasts have wide potential applications in biotechnology, for some of them can produce β-galactosidase and killer toxins.

  7. Heterotrophic bacteria in soils of Larsemann Oasis of East Antarctica

    Science.gov (United States)

    Churilin, Nikita; Soina, Vera

    2015-04-01

    The study of diversity and functional state of microorganisms in subsurface rocks layers, their participation in the biochemical weathering and formation of organic horizons of soils is important for understanding ecology and microorganisms in Antarctic soils. The study of cultured forms of microorganisms and their potential viability is still relevant to characterize the physiological state, biological activity and resilience of microorganisms involved in the initial soil formation. Improvement of isolation techniques of viable bacteria from the extreme habitats has a particular importance for rising the efficiency of environmental monitoring. The aim of the study was to investigate the viable heterotrophic bacteria involved in the formation of soils from wet valleys Larsemann Oasis, which is one of the warmest ice-free space of East Antarctica. Soil samples were taken from the intermountain humid valleys, where silt-gravelly substrates formed moss, algae, lichen cover. We used nutrient solutions (trypticase soy, R2A and glucose-peptone) to isolate cultured bacteria and study their morphological types in the light microscope. The total number of microorganisms was determined by fluorescent microscopy with acridine orange. SEM was used for morphological studies of bacterial communities in situ. To activate the growth processes we added into nutrient solutions various regulatory metabolites that have dose-dependence and operate at the community level. Physiological and functional conditions were determined by the duration of the lag phase and specific growth rate of bacterial communities in nutrient solutions containing various organic substrates. Soils form under protection of «stone pavement» and organisms leave the surface, so the forming organo-mineral horizon occurs inside of rock, thus the microprofile can form on both sides of the organic horizons. UV radiation, lack of moisture and strong wind are main limiting factors for microorganisms' growth in

  8. 干热河谷20年生2种人工恢复植被个体生长特性研究%Individual growth characteristics of two tree species after 20 years of ecological restoration in a dry-hot valley of southwestern China

    Institute of Scientific and Technical Information of China (English)

    李彬; 唐国勇; 李昆; 高成杰; 刘方炎; 王小菲

    2013-01-01

    The growth characteristics of 20-year-old Eucalyptus camaldulensis Dehuh and Leucaena leucocephala (Lam. ) Dewit in the monocultures and their mixed-species plantations in the Yuanmou Dry-hot Valley of southwestern China were investigated by a stem analysis. The results showed that all the DBH, height and volume of timber of E. camaldulensis in the mixed-species plantations grew faster than those in monoculture. The average increment and current annual increment of height of both the species declined. DBH of the two species declined during 5-10 years but increased during 10-15 years beside E. camaldulensis in the mixed-species plantations, and then all decreased. The changing rates of Logistic growth curve could scale 5-10, 10-25, and > 25 years as the early growth period, rapid growth period and stationary growth stage, respectively. Based on this model, E. camaldulensis in the monoculture and mixed-species plantations will obtain the quantitative maturity at the 23 years and 25 years after the trees were planted, respectively, and both the 24 years for L. leucocephala in the monoculture and mixed-species plantations. Some management measures such as thinning and increasing water and fertilizer supply in the early and rapid growth period were recommended based on this study.%以元谋干热河谷20年生赤桉纯林、新银合欢纯林以及赤桉×新银合欢混交林为研究对象,对其林木单株进行树干解析,研究不同造林模式下2个树种的生长特性.结果表明:1)新银合欢的混植促进了赤桉的生长.2)赤桉、新银合欢树高平均生长量和连年生长量总体均呈下降趋势,胸径的平均生长量和连年生长量在5 ~10年呈下降趋势,在10 ~ 15年期间呈上升趋势(除混交林内赤桉),之后又下降.3)根据Logistic生长曲线的变化率,可将赤桉、新银合欢5 ~10年划分为生长初期,10 ~ 25年为生长快速期,之后为生长稳定期;经模型预测:赤桉纯林在23年时达到

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

    Science.gov (United States)

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

    2014-05-01

    -related exhumation in interior East Antarctica. This raises the question of whether the modern Gamburtsevs may instead have been uplifted solely in response to changes in Cenozoic erosion patterns during the early stages of East Antarctic Ice Sheet formation superimposed upon an a Permian-age rift flank, or an even older highland. To address this question we combine results from: i) analyses of the subglacial landscape for the GSM (Rose et al., 2013 EPSL) with; ii) 2D and preliminary 3D flexural models of peak uplift caused by the isostatic responses to fluvial and glacial valley incision processes. We also compare geophysical relief and isostatic model outputs with estimates of erosion rates since the Oligocene and the total amount of incision estimated for the adjacent Lambert rift region (Thomson et al. 2013, Nature Geoscience). Flexural modelling outputs were also compared against the present-day elevations of up to 1500 m a.s.l of uplifted Oligocene-early Miocene glacial-marine sediments in the Lambert Glacier (Hambrey et al., 2000, Geology). Flexural models yield new estimates of peak uplift and regional lowering for continuous and broken-plate approximations respectively. These results can also be used to re-assess the possible ranges of pre-incision elevations of the "Gamburtsev plateau", which is of key importance when modelling early East Antarctic ice sheet development (e.g. De Conto and Pollard, Nature 2003).

  10. Brief Study on Historical Causes and Countermeasures of Dry-hot Valley Catastrophes of Jinsha River in Yunnan——On the Ecological Value of the Traditional Means of Livelihood of the Di and Qiang Nationalities%云南金沙江流域干热河谷灾变的历史成因及治理对策探究——兼论氐羌族系各民族传统生计方式的生态价值

    Institute of Scientific and Technical Information of China (English)

    马国君; 李红香

    2012-01-01

    Before Qing Dynasty,Jinsha River valley which located in Yunnan was famous for its dense forests,plentiful grasslands and humid climate.At that time,dry-hot valley catastrophes didn't occur.However,when the time went into Qing Dynasty,with increased immigration and disorder of development and management,coupled with the government's policy is not compatible with the local ecological system,after a long time,it led to the damage to the coexistence of diverse forest ecosystems,expansion of dry-hot valley catastrophe and jeopardizing human survival and development.To cure dry-hot valley catastrophes of Jinsha River in Yunnan,we should learn from historical experience of the development and utilize the original habitat of the nation's traditional ecological knowledge and skills.%清代以前,云南境内的金沙江流域河谷地带森林茂密、草原丰美、气候湿润,并未呈现干热河谷灾变景观。入清后,随着移民的增加,开发管理的无序,加之引入的经营模式与当地生态系统不相兼容,经长期积累后,毁损了多样并存的森林生态系统,诱发了干热河谷生态灾变的扩大化,危害了人类的生存和发展。要根治今天云南境内金沙江流域干热河谷灾变,应借鉴历史的经验,充分发掘、利用原生地各民族的传统生态知识和技能,这一地区干热河谷灾变救治才可望收到理想成效。

  11. Evaluation of four global reanalysis products using in situ observations in the Amundsen Sea Embayment, Antarctica

    Science.gov (United States)

    Jones, R. W.; Renfrew, I. A.; Orr, A.; Webber, B. G. M.; Holland, D. M.; Lazzara, M. A.

    2016-06-01

    The glaciers within the Amundsen Sea Embayment (ASE), West Antarctica, are amongst the most rapidly retreating in Antarctica. Meteorological reanalysis products are widely used to help understand and simulate the processes causing this retreat. Here we provide an evaluation against observations of four of the latest global reanalysis products within the ASE region—the European Centre for Medium-Range Weather Forecasts Interim Reanalysis (ERA-I), Japanese 55-year Reanalysis (JRA-55), Climate Forecast System Reanalysis (CFSR), and Modern Era Retrospective-Analysis for Research and Applications (MERRA). The observations comprise data from four automatic weather stations (AWSs), three research vessel cruises, and a new set of 38 radiosondes all within the period 2009-2014. All four reanalyses produce 2 m temperature fields that are colder than AWS observations, with the biases varying from approximately -1.8°C (ERA-I) to -6.8°C (MERRA). Over the Amundsen Sea, spatially averaged summertime biases are between -0.4°C (JRA-55) and -2.1°C (MERRA) with notably larger cold biases close to the continent (up to -6°C) in all reanalyses. All four reanalyses underestimate near-surface wind speed at high wind speeds (>15 m s-1) and exhibit dry biases and relatively large root-mean-square errors (RMSE) in specific humidity. A comparison to the radiosonde soundings shows that the cold, dry bias at the surface extends into the lower troposphere; here ERA-I and CFSR reanalyses provide the most accurate profiles. The reanalyses generally contain larger temperature and humidity biases, (and RMSE) when a temperature inversion is observed, and contain larger wind speed biases (~2 to 3 m s-1), when a low-level jet is observed.

  12. Comparative account of benthic community at two different locations in the continental Antarctica

    Digital Repository Service at National Institute of Oceanography (India)

    Ingole, B.S.; Dhargalkar, V.K.

    Data on faunal communities, abundance and biomass were collected from seven stations in the Queen Maud Land shelf, Lazarev Sea, East Antarctica and three stations in Atca Ice Port, Weddell Sea, West Antarctica. The sampling depth ranged from 70...

  13. 27 CFR 9.82 - Potter Valley.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Potter Valley. 9.82... Potter Valley. (a) Name. The name of the viticultural area described in this section is “Potter Valley.” (b) Approved map. The approved maps for the Potter Valley viticultural area are the U.S.G.S....

  14. 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

  15. A solar photovoltaic power system for use in Antarctica

    Science.gov (United States)

    Kohout, Lisa L.; Colozza, A. J.; Merolla, A.

    1994-01-01

    A solar photovoltaic power system was designed and built at the NASA Lewis Research Center as part of the NASA/NSF Antarctic Space Analog Program. The system was installed at a remote field camp at Lake Hoare in the Dry Valleys and provided a six-person field team with the power to run personal computers and printers, lab equipment, lightning, and a small microwave oven. The system consists of three silicon photovoltaic sub-arrays delivering 1.5 kW peak power, three lead-acid gel battery modules supplying 2.4 kWh, and electrical distribution system which delivers 120 Vac and 12 Vdc to the user. The system was modularized for each of deployment and operation. Previously the camp has been powered by diesel generators, which have proven to be both noisy and polluting. The NSF, in an effort to reduce their dependence on diesel fuel from both and environmental and cost standpoint is interested in the use of alternate forms of energy, such as solar power. Such a power system will also provide NASA with important data on system level deployment and operation in a remote location by a minimally trained crew, as well as validate initial integration concepts.

  16. Social, occupational and cultural adaptation in Antarctica

    Science.gov (United States)

    Nicolas, Michel; Bishop, Sheryl; Weiss, Karine; Gaudino, Marvin

    2016-07-01

    Life in isolated and confined environments (ICEs, e.g., polar stations, submarine or space missions), is subject to important constraints which can generate psychosociological impaired outcomes. This study investigated psychological, social, occupational and cultural variables which are among the most important determinants in adaptation to a one-year wintering in Antarctica with 13 international participants. Our findings confirm and give further insight into the role of social (Cohesiveness, Social Support) and occupational (Implementation / Preparedness, Counterproductive Activity, Decision Latitude and Psychological Job Demands) dimensions of adaptation to ICE environments. Relationships between various social and occupational dimensions studies reflected detrimental effects ranging from decrements in cohesiveness, social support and work performance which differed across professional status and multicultural factors. These psychosocial issues have important implications for pre-mission selection and training, monitoring and support of crews during the mission and post-mission readaptation. Operational recommendations are suggested to improve adaptation, success and well-being for long-term ICE missions, e.g., to Mars and beyond.

  17. AGB Star Variability Observed from Antarctica

    Science.gov (United States)

    Briguglio, Runa

    2008-04-01

    We present here a short account of the first observations done at the Italo-French base of Dome C, Antarctica, in the field of Mira variability. The observations aimed at improving our knowledge of the variability period of some important Long Period Variables (LPV), to be used in Period-Luminosity criteria for determining in a reliable way the absolute magnitudes and hence the distances of AGB stars. The observations were taken during the 2007 winter campaign, using the small-IRAIT telescope, a 25 cm Cassegrain instrument capable of multiband photometry. The telescope was equipped with a reliable remote control system, which allowed us to get very high duty-cycle observations (the highest efficient was obtained in July 2007, with more than 98% of on-source time, over 9 ``solar'' days during the long polar night). The experiments done with small IRAIT will be precious as a pathfinder, for defining the observational strategies of the larger IRAIT (International Robotic Antarctic Infrared Telescope [1]), an 80-cm aperture telescope, working mainly in IR, that will be installed in Dome C next year.

  18. Phytoplankton Bloom Phenology near Palmer Station Antarctica

    Science.gov (United States)

    Crews, L.; Doney, S. C.; Kavanaugh, M.; Ducklow, H. W.; Schofield, O.; Glover, D. M.

    2015-12-01

    West Antarctic Peninsula (WAP) phytoplankton bloom phenology is coupled to growing season water column stratification precipitated by seasonal warming and the melting of winter sea-ice. Previous studies document declining bloom magnitude over decadal timescales in conjunction with decreasing sea-ice extent and duration in the Northern WAP, but less work has been to done explain the observed inter-annual variability in this region. Here we use a high-resolution in situ time series collected by the Palmer Station Antarctica Long Term Ecological Research program and satellite ocean color imagery to investigate the underlying mechanisms controlling phytoplankton bloom timing and magnitude near Palmer Station. We pair chlorophyll and CTD measurements collected twice per week during the austral summer, 1992—2003, with satellite ocean color and ice fractional cover data to examine bloom development and within-season trends in mixed layer depth. Initial results suggest a possible shift over time with spring/summer blooms occurring earlier in the growing season reflecting earlier sea-ice free conditions. Net phytoplankton accumulation rates are also computed and compared against growth estimates. Our results can be used to develop and validate models of coastal Antarctic primary production that better represent inter-annual primary production variability.

  19. Physical properties of aerosols at Maitri, Antarctica

    Indian Academy of Sciences (India)

    C G Deshpande; A K Kamra

    2004-03-01

    Measurements of the submicron aerosol size distribution made at the Indian Antarctic station, Maitri (70° 45′S, 11° 44′E) from January 10th to February 24th, 1997, are reported. Total aerosol concentrations normally range from 800 to 1200 particles cm-3 which are typical values for the coastal stations at Antarctica in summer. Aerosol size distributions are generally trimodal and open- ended with a peak between 75 and 133nm and two minima at 42 and 420 nm. Size distributions remain almost similar for several hours or even days in absence of any meteorological disturbance. Total aerosol concentration increases by approximately an order of magnitude whenever a low pressure system passes over the station. Based on the evolution of aerosol size-distributions during such aerosol enhancement periods, three types of cases have been identified. The nucleation mode in all three cases has been suggested to result from the photochemical conversion of the DMS emissions transported either by the marine air or by the air from the ice-melt regions around Maitri. Subsidence of midtropospheric air during the weakening of radiative inversion is suggested as a possible source of the nucleation mode particles in the third case. Growth of the nucleation mode particles by condensation, coagulation and/or by cloud processes has been suggested to be responsible for other modes in size distributions.

  20. Ozone profiles above Palmer Station, Antarctica

    Science.gov (United States)

    Torres, Arnold L.; Brothers, George

    1988-01-01

    NASA's Goddard Space Flight Center/Wallops Flight Facility conducted a series of 52 balloon-borne measurements of vertical ozone profiles over the National Science Foundation (NSF) research facility at Palmer Station, Antarctica (64 deg 46 S, 64 deg 3 W) between August 9 and October 24, 1987. High resolution measurements were made from ground level to an average of 10 mb. While much variation was seen in the profile amounts of ozone, it is clear that a progressive depletion of ozone occurred during the measurement period, with maximum depletion taking place in the 17 to 19 km altitude region. Ozone partial pressures dropped by about 95 percent in this region. Shown here are plotted time dependences of ozone amounts observed at 17 km and at arbitrarily selected altitudes below (13 km) and above (24 km) the region of maximum depletion. Ozone partial pressure at 17 km is about 150nb in early August, and has decreased to less than 10nb in the minimums in October. The loss rate is of the order of 1.5 percent/day. In summary, a progressive depletion in stratospheric ozone over Palmer Station was observed from August to October, 1987. Maximum depletion occurred in the 17 to 19 km range, and amounted to 95 percent. Total ozone overburden decreased by up to 50 percent during the same period.

  1. CRIA Sians A areement with Rubber Valley

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The signing ceremony of establishing strategic partnership between China Rubber Industry Association and Rubber Valley Co., Ltd. was held in Rubber Valley on September 13. Leaders such as Xu Wenying, Deputy Secretary-General of CRIA, repre-senting CRIA, and Zhang Yan, Deputy Director of Rubber Valley Management Committee and General Manager of Rubber Valley Co., Ltd., representing Rubber Valley, signed on the cooperation agreement. Fan Rende, President of CRIA, Cai Quanji,

  2. 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.

  3. 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...

  4. 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.

  5. 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...

  6. 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.……

  7. Summertime wind climate in Yerevan: valley wind systems

    Science.gov (United States)

    Gevorgyan, Artur

    2017-03-01

    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.

  8. 45 CFR 674.4 - Restrictions on collection of meteorites in Antarctica.

    Science.gov (United States)

    2010-10-01

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

  9. Where does CO2 in Antarctica cool the atmosphere ?

    Science.gov (United States)

    Schmithüsen, Holger; Notholt, Justus; König-Langlo, Gert; Lemke, Peter; Jung, Thomas

    2016-04-01

    In a recent study we have shown that for the high altitude plateau in Antarctica CO2 causes a surplus in infrared emission to space compared to what is emitted from the surface. This corresponds to a negative greenhouse effect, and is due to the fact that for this region the surface is typically colder than the atmosphere above, opposite to the rest of the world. As a consequence, for this region an increase in CO2 leads to an increase in the energy loss to space, leading to an increase in the negative greenhouse effect. We now studied in more detail the radiative effect of CO2 and compared the results with available measurements from Antarctica. H. Schmithüsen, J. Notholt, G. Köngig-Langlo, T, Jung. How increasing CO2 leads to an increased negative greenhouse effect in Antarctica. Geophysical Research Letters, in press, 2015. doi: 10.1002/2015GL066749.

  10. Provenance of dust to Antarctica: A lead isotopic perspective

    Science.gov (United States)

    Gili, Stefania; Gaiero, Diego M.; Goldstein, Steven L.; Chemale, Farid, Jr.; Koester, Edinei; Jweda, Jason; Vallelonga, Paul; Kaplan, Michael R.

    2016-03-01

    Antarctic ice preserves an ~800 kyr record of dust activity in the Southern Hemisphere. Major efforts have been dedicated to elucidate the origin of this material in order to gain greater insight into the atmospheric dust cycle. On the basis of Pb isotopes in Antarctic dust samples and potential sources, this contribution demonstrates for the first time that Patagonia is the main contributor of dust to Antarctica during interglacial periods as well as glacials, although the potential importance of Tierra del Fuego remains unclear because of its geochemical similarities to Patagonia. An important new finding is that the Puna-Altiplano sector of the continent is a second important dust source to eastern Antarctica during both glacials and interglacials, being more prominent during interglacials. The data indicate South America is the primary dust source to Antarctica during both glacials and interglacials.

  11. Permafrost and periglacial research in Antarctica: New results and perspectives

    Science.gov (United States)

    Guglielmin, Mauro; Vieira, Gonçalo

    2014-11-01

    In the last two years the research within the Antarctic Permafrost, Periglacial Environments and Soils (ANTPAS) Expert Group of the Scientific Committee on Antarctic Research (SCAR) and Working Group of the International Permafrost Association (IPA) provided new results on the dynamics of periglacial environments both in Maritime and Continental Antarctica. In continental Antarctica despite the absence of air warming, in the last 15 years an active layer thickening and acceleration of permafrost degradation erosional phenomena were reported, these being mainly related to the increase of solar radiation. On the other hand, in Maritime Antarctica, with a dramatic air warming, permafrost degradation has been observed, but the role of snow cover on the ground energy balance and consequently on permafrost and active layer has been underlined. Moreover, many contributions on the knowledge on the characteristics of the Antarctic soils were carried out in several areas along a wide latitudinal range.

  12. Ongoing deformation of Antarctica following recent Great Earthquakes

    Science.gov (United States)

    King, Matt; Santamaría-Gómez, Alvaro

    2016-04-01

    The secular motion of Antarctica is thought to be almost everywhere governed by horizontal rigid plate rotation plus three-dimensional deformations due to past and present changes in ice-ocean loading, known as glacial isostatic adjustment (GIA). We use geodetic data to investigate deformation following the 1998 magnitude ~8.1 Antarctic intra-plate Earthquake, and show sustained three-dimensional deformation along East Antarctica's coastline, 600 km from the rupture location. Using a model of viscoelastic deformation we are able to match observed northward velocity changes, and either east or height, but not all three directions simultaneously, apparently partly due to lateral variations in mantle rheology. Our modeling predicts much of Antarctica may still be deforming, with further deformation possible from the 2004 Macquarie Ridge Earthquake. This previously unconsidered mode of Antarctic deformation affects geodetic estimates of plate motion and GIA; its viscous nature raises the prospect of further present-day deformation due to earlier Great Earthquakes.

  13. Molecular Cytogenetic Analysis of Deschampsia antarctica Desv. (Poaceae), Maritime Antarctic.

    Science.gov (United States)

    Amosova, Alexandra V; Bolsheva, Nadezhda L; Samatadze, Tatiana E; Twardovska, Maryana O; Zoshchuk, Svyatoslav A; Andreev, Igor O; Badaeva, Ekaterina D; Kunakh, Viktor A; Muravenko, Olga V

    2015-01-01

    Deschampsia antarctica Desv. (Poaceae) (2n = 26) is one of the two vascular plants adapted to the harshest environment of the Antarctic. Although the species is a valuable model for study of environmental stress tolerance in plants, its karyotype is still poorly investigated. We firstly conducted a comprehensive molecular cytogenetic analysis of D. antarctica collected on four islands of the Maritime Antarctic. D. antarctica karyotypes were studied by Giemsa C- and DAPI/C-banding, Ag-NOR staining, multicolour fluorescence in situ hybridization with repeated DNA probes (pTa71, pTa794, telomere repeats, pSc119.2, pAs1) and the GAA simple sequence repeat probe. We also performed sequential rapid in situ hybridization with genomic DNA of D. caespitosa. Two chromosome pairs bearing transcriptionally active 45S rDNA loci and five pairs with 5S rDNA sites were detected. A weak intercalary site of telomere repeats was revealed on the largest chromosome in addition to telomere hybridization signals at terminal positions. This fact confirms indirectly the hypothesis that chromosome fusion might have been the cause of the unusual for cereals chromosome number in this species. Based on patterns of distribution of the examined molecular cytogenetic markers, all chromosomes in karyotypes were identified, and chromosome idiograms of D. antarctica were constructed. B chromosomes were found in most karyotypes of plants from Darboux Island. A mixoploid plant with mainly triploid cells bearing a Robertsonian rearrangement was detected among typical diploid specimens from Great Jalour Island. The karyotype variability found in D. antarctica is probably an expression of genome instability induced by environmental stress factors. The differences in C-banding patterns and in chromosome distribution of rDNA loci as well as homologous highly repeated DNA sequences detected between genomes of D. antarctica and its related species D. caespitosa indicate that genome reorganization involving

  14. Ice plug prevents irreversible discharge from East Antarctica

    Science.gov (United States)

    Mengel, M.; Levermann, A.

    2014-06-01

    Changes in ice discharge from Antarctica constitute the largest uncertainty in future sea-level projections, mainly because of the unknown response of its marine basins. Most of West Antarctica's marine ice sheet lies on an inland-sloping bed and is thereby prone to a marine ice sheet instability. A similar topographic configuration is found in large parts of East Antarctica, which holds marine ice equivalent to 19 m of global sea-level rise, that is, more than five times that of West Antarctica. Within East Antarctica, the Wilkes Basin holds the largest volume of marine ice that is fully connected by subglacial troughs. This ice body was significantly reduced during the Pliocene epoch. Strong melting underneath adjacent ice shelves with similar bathymetry indicates the ice sheet's sensitivity to climatic perturbations. The stability of the Wilkes marine ice sheet has not been the subject of any comprehensive assessment of future sea level. Using recently improved topographic data in combination with ice-dynamic simulations, we show here that the removal of a specific coastal ice volume equivalent to less than 80 mm of global sea-level rise at the margin of the Wilkes Basin destabilizes the regional ice flow and leads to a self-sustained discharge of the entire basin and a global sea-level rise of 3-4 m. Our results are robust with respect to variation in ice parameters, forcing details and model resolution as well as increased surface mass balance, indicating that East Antarctica may become a large contributor to future sea-level rise on timescales beyond a century.

  15. New aerogeophysical evidences of riftogenic crust over Princess Elizabeth Land, East Antarctica

    Science.gov (United States)

    Golynsky, Dmitry; Golynsky, Alexander; Kiselev, Alexander

    2014-05-01

    Analysis of radio-echosounding and RADARSAT mosaic data by Golynsky & Golynsky (2007) reveals at least 500 km long structure called the Gaussberg rift over the eastern part of Princess Elizabeth Land, East Antarctica. This previously unknown continuous structure consists of two sub-parallel depressions separated by segmented horst-like escarpments that are largely hidden under the East Antarctic Ice Sheet. One of these segments is Mount Brown escarpment, which reaches a height of 1982 m. It was suggested that the rift was probably initiated at the same time as the Lambert graben, marked by the deposition of coal-bearing Permian sediment and probably inherited the tectonically weak zone of the Proterozoic igneous belt along its boundary with the Vestfold-Rauer Archean cratonic block. The Gaussberg rift may be considered as a hypothetical accommodation zone of the Carboniferous-Permian intracontinental rift along 4000 km of the West Australian and East Indian margins, which filled with thick Permian-Triassic sediment including alluvial coals (Harrowfield et al., 2005). Supposedly, the Gaussberg rift corresponds to the Mahanadi Valley of East India and the Lambert rift system has across-rift alignment with Godavari Valley. New Russian ice penetrating radar data collected in 2012-13 over western part of the suggested rift shows that in places the floor of the central depression is more than 1000 m below sea level. Horst and graben systems are heavily segmented by N-S running transverse lineaments that in addition clearly discernible in the RADARSAT data. New high-quality magnetic data show that severe changes in the magnetic fabric observed in vicinity, along strike and over borders of the structure are though to be due to the tectonic nature. Interruption of the long wavelength high-intensity magnetic anomaly belt associated with southern boundary of the Vestfold-Rauer cratonic block near the western depression can't be explained by a subglacial erosion, in our

  16. Ambient Radon-222 Monitoring in Amargosa Valley, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    L.H. Karr; J.J. Tappen; D. Shafer; K.J. Gray

    2008-06-05

    As part of a program to characterize and baseline selected environmental parameters in the region around the proposed repository at Yucca Mountain, Nevada, ambient radon-222 monitoring was conducted in the rural community of Amargosa Valley, the community closest to the proposed repository site. Passive integrating radon monitors and a continuous radon monitoring instrument were deployed adjacent to the Community Environmental Monitoring Program (CEMP) (http://www.cemp.dri.edu/index.html) station located in the Amargosa Valley Community Center near the library. The CEMP station provided real-time ambient gamma exposure and meteorological data used to correct the integrated radon measurements as well as verify meteorological data collected by the continuous radon monitoring instrument. Additionally, different types of environmental enclosures that housed the monitors and instrument were used to determine if particular designs influenced the ambient radon measurements.

  17. Vegetation biomass allocation and its spatial distribution after 20 years ecological restoration in a dry-hot valley in Yuanmou, Yunnan Province of Southwest China%元谋干热河谷20年生人工恢复植被生物量分配与空间结构特征

    Institute of Scientific and Technical Information of China (English)

    李彬; 唐国勇; 李昆; 高成杰; 刘方炎; 王小菲

    2013-01-01

    By using layering harvest method,a comparative study was conducted on the biomass allocation and its spatial distribution of 20-year-old Eucalyptus camaldulensis plantation,Leucaena leucocephala plantation,and E.camaldulensis-L.leucocephala plantation in Yuanmou dry-hot valley of Yurman Province,Southwest China.The stand biomass in the mixed E.camaldulensis-L leucocephala plantation (82.99 t · hm-2) was between that of monoculture E.camaldulensis plantation (60.64 t · hm-2) and L leucocephala plantation (127.79 t · hm-2).The individual tree biomass of E.camaldulensis in the mixed plantation (44.32 kg) was 49.8% higher than that in monoculture plantation (29.58 kg).The branch and leaf biomass of L.leucocephala (25.4%) in monoculture plantation was larger than that of E.camaldulensis (8.9%) in monoculture plantation,and the aboveground biomass distribution ratio (78.0%) of L.leucocephala (25.4%) was also higher than that of E.camaldulensis (73.4%).The roots of L.leucocephala in both monoculture and mixed plantations were mainly distributed in 0-40 cm soil layer,while those of E.camaldulensis in monoculture and mixed plantations were mainly found in 0-80 cm and 0-60 cm,respectively.The proportion of biomass allocated to roots including medium roots,small roots,and fine roots of L.leucocephala in mixed plantation was higher than that in monoculture plantation,but it was contrary for E.camaldulensis.It was suggested that introducing L.leucocephala in E.camaldulensis plantation promoted the growth of E.camaldulensis,especially for its aboveground biomass,and increased the amount of lateral roots in 0-20 cm soil layer,which had significance in soil and water conservation in the study area.%采用分层收获法,对元谋干热河谷20年生赤桉、新银合欢纯林及其混交林的生物量分配与空间结构进行对比研究.结果表明:混交林林分生物量(82.99 t·hm-2)介于赤桉纯林(60.64 t ·hm-2)与新银合欢纯林(127.79 t·hm-2)之

  18. Soil seed bank and aboveground vegetation in Jinshajing Hot-Dry River Valley Hillslope vegetation restoration site%金沙江干热河谷山地植被恢复区土壤种子库和地上植被研究

    Institute of Scientific and Technical Information of China (English)

    罗辉; 王克勤

    2006-01-01

    Soil seed bank plays an important role in the composition of different plant communities and especially in their conservation. Although Soil seed bank, aboveground vegetation and their relationship have been the subject of much recent attention, little is known about the size and species composition of soil seed bank and aboveground vegetation in semi-arid hillslope grasslands and understanding of how these components interact to determine the importance of seed banks to regeneration is limited.We assessed the size and species composition of a soil seed bank and aboveground vegetation in an experiment with 36 vegetation quadrats and 108 soil samples in terrace, slope, gully and grazing land that represent a range of habitats within a hillslope grassland in Jinshajing hot-dry river valley of Yunnan. Terrace, slope and gully represent restored site and grazing land typifies unrestored site. We identified 21 taxa in the seed bank with a median of 7 species/m2 and a median density of 5498 seeds/m2, while in aboveground vegetation, 19 species were observed with a median of 6 species/m2 and a median density of 1088 plants/m2. Both seed bank density and aboveground vegetation density among grazing land, gully, slope and terrace differed significantly. There was an absolutely high proportion of herbaceous species in the seed bank and aboveground vegetation. Gramineae predominated over both seed bank and vegetation. The most frequent seeds and plants were Bothriochloa pertusa (L.) A. Camus and Heteropogon contortus (L.) Beauv that had the highest individual number, importance value and biomass. In the seed bank, the seeds of Bothriochloa pertusa (L.) A. Camus and Heteropogon contortus (L.) Beauv accounted for 50.68% and for 33.10% of the total seeds respectively. In aboveground vegetation, the individual number of Bothriochloa pertusa (L.) A. Camus accounted for 55.66% of the total and Heteropogon contortus (L.) Beauv accounted for 29.86%. The biomass of Bothriochloa

  19. Effects of Stylosanthes guianensis Plantations under Different Land Conditions in Dry-hot Valley of Yunnan Province%干热河谷退化山地不同立地条件种植柱花草效应研究

    Institute of Scientific and Technical Information of China (English)

    龙会英; 张德; 金杰; 何光熊; 王永林; 保海坤; 史亮涛; 张明忠

    2011-01-01

    Stylosanthes guianensis was introduced to degraded mountain land in Dry-hot valley of Yuanmou County.Its major phonological periods,growth trend,biology and effects of cover in winter were studied in different land conditions.The results showed that S.guianensis could be planted in different land conditions and finish its major phonological periods.In addition,it had a good productivity and cover effect no matter in terrace or sloping field.The phonological periods in terrace and sloping field were similar.Because the water holding capacity was higher in terrace,biomass,rate of growth of S.guianensis and moisture of land surface in terrace were higher than in sloping field.Because the land surface was covered by these plants,evaporation was reduced.So it could be effective to keep moisture of land surface in terrace and sloping field.The soil moisture was higher than no-planted lands in 0~20 cm and 20~40 cm depth in both plantation conditions.It was helpful for S.guianensis to fight against drought and to re-grow in next year.In addition,S.guianensis could regulate ground temperature of plantation soil.The temperature in plantation soil was higher than no-planted soil at 8:00 a.m.and 18:00 p.m.It was helpful for S.guianensis to fight against a cold and survive through winter.Ground temperature of S.guianensis plantation was lower than no-planted soil at 14:00 p.m.and ground temperature of soil was decreased effectively by S.guianensis.Bulk density of soil planting S.guianensis was lower than before in both terrace and sloping field.The infiltration capability and configuration of planting soil were also improved.Soil fertility was increased in S.guianensis plantation due to nitrogen-fixed effect and litter decomposition.The microbial biomass was also increased.%以云南省元谋干热河谷退化山地不同立地条件下种植的柱花草(Stylosanthes guianensis)为供试植物,研究柱花草的物候期、生长速率、生物量及覆盖效应。

  20. Influence factors of morphological development of soil cracks in degraded slopes in Yuanmou dry-hot valley region%元谋干热河谷区退化坡地土壤裂缝形态发育的影响因子

    Institute of Scientific and Technical Information of China (English)

    熊东红; 杨丹; 李佳佳; 苏正安; 董一帆; 翟娟

    2013-01-01

      土壤开裂影响土体内水分散失、溶质运移及土体结构,是元谋干热河谷坡地退化的一个重要过程及特征。该文通过对元谋干热河谷退化坡地典型土壤裂缝样方的实地调查及数据的室内分析,系统分析了土壤理化属性对裂缝发育程度的影响。研究结果表明:1)土壤裂缝发育程度与土壤黏粒含量、土壤胀缩度、土壤容重呈正相关,与土壤有机质含量、土壤总孔隙度呈较弱的负相关;2)土壤裂缝发育程度的首要影响因子是土壤结构性因子(土壤容重、总孔隙度和黏粒含量),其次为土壤胀缩度,然后是土壤有机质。该研究可为进一步研究土壤开裂导致的土地退化过程奠定基础,为制定开裂土体的改良措施提供参考。%Soil cracking is an important process and feature of the slope degradation in Yuanmou Dry-hot Valley Region, which influences water evaporation, solutes transport and soil structure. In this paper, 25 soil crack quads were investigated by using the photography method to describe the morphology of soil cracks, and meanwhile, soil samples were also obtained at soil depth 0-30 cm and >30-60 cm in the same quad. The crack area density (Dc) was obtained by ArcGIS 9.0. The values for soil physico-chemical properties were also obtained by laboratory analysis. And then, the influences of soil physico-chemical properties on the development degrees of soil cracks were analyzed by application of statistical analysis methods. The Results indicate that: (1) The development degrees of soil cracks have a positive correlation with clay content, swell-shrink property and bulk density, and are negatively correlated to organic content and soil porosity. Dc, which is the quantitative indicator for the development degrees of soil cracks has been found to have a significant strong correlation with clay content, their coefficients were 0.97 and 0.95 for 0-30 cm layer and for >30-60 cm

  1. Analysis of effects of different modes of irrigation and mulching on water-saving and drought-resistance in sloping orchards of dry-hot valley%干热河谷坡地果园灌溉覆盖方式的抗旱节水效应分析

    Institute of Scientific and Technical Information of China (English)

    米艳华; 陆琳; 黎其万; 陈艺棋; 段曰汤; 杨顺林; 朱红业

    2011-01-01

    在金沙江干热河谷坡地青枣果园设置裸地漫灌,直沟和目字沟埋草沟灌,地面秸秆、生物覆盖浸灌以及直沟埋草沟灌加地面秸秆覆盖等6种灌水疆盖实验,研究干热河谷坡地果园覆盖灌水方式的抗旱节水效应,筛选适宜的节水抗旱灌溉技术.结果表明:土壤保水、蓄水能力表现为覆盖漫灌高干开沟埋革沟灌,显著高于裸地漫灌.灌溉水利用率和经济效益则表现为:目字沟、直沟埋草沟灌>地面秸秆、生物覆盖漫灌>裸地漫灌.直沟埋草沟灌加地面秸秆覆盖处理的灌水次数最少,灌水量不到裸地漫灌对照的28.6%,灌溉水利用率是对照的6.7倍.节水效果依此表现为:直沟埋草沟灌+地面秸秆覆盖>>目字沟埋草沟灌≥地面秸秆覆盖漫灌>直沟埋草沟灌≥地面生物覆盖漫灌>>裸地漫灌(CK).经济效益最好的是直沟埋草沟灌+地面秸秆覆盖处理,其次是目字沟埋草沟灌,纯效益分别是裸地漫灌的2.36倍和2.16倍,产投比是对照的1.9倍和1.8倍.结果说明,在干热河谷燥红土果园,开沟埋草沟灌,地面覆盖,使灌溉水渗透土壤,减少地表径流和蒸散损失,提高土壤的保蓄水能力,能有效提高灌溉水的利用率和果园经济效益.%In jujube orchards of the slope area in the dry-hot valley of Jinsha River, six modes of irrigation and mulching were set in the experiment, namely flood irrigation in bare land(CK), furrow irrigation with straw buried in straight ditches, furrow irrigation with straw buried in mesh ditches, flood irrigation with plants covering, flood irrigation with soil surface straw mulching, and furrow irrigation with straw buried in straight ditch + soil surface straw mulching. The results show that, for soil conservation and water storage capacity, flood irrigation with soil surface straw mulching is better than furrow irrigation with straw buried in straight ditches, and much better than CK. As for rrigation water use

  2. Mean thermospheric winds observed from Halley, Antarctica

    Directory of Open Access Journals (Sweden)

    R. I. Crickmore

    Full Text Available Thermospheric winds on a total of 237 nights have been studied for the effects due to geomagnetic activity, solar flux, and season. The observations have been made from 1988 to 1992 by a Fabry-Perot interferometer (FPI operating at Halley (75.5°S, 26.6°W, Antarctica. This is the first statistical study of thermospheric winds near the southern auroral zone. The main factor affecting the wind velocities is the geomagnetic activity. Increases in activity cause an increase in the maximum equatorward wind, and cause the zonal wind in the evening to become more westward. Smaller changes in the mean wind occur with variations in season and solar flux. The small variation with solar flux is more akin to the situation found at mid-latitudes than at high latitudes. Since the geomagnetic latitude of Halley is only 61°, it suggests that the variability of the wind with solar flux may depend more on geomagnetic than geographic latitude. These observations are in good agreement with the empirical Horizontal Wind Model (HWM90. However, comparisons with predictions of the Vector Spherical Harmonic Model (VSH show that for low geomagnetic activity the predicted phases of the two components of the wind closely resemble the observations but the modelled amplitudes are too small by a factor of two. At high geomagnetic activity the major differences are that modelled zonal velocity is too westward in the evening and too eastward after 04 UT. The modelled ion densities at the F-region peak are a factor of up to 9 too large, whilst the predicted mean value and diurnal variation of the altitude of the peak are significantly lower than those observed. It is suggested that these differences result from the ion loss rate being too low, and an inaccurate model of the magnetic field.

  3. Electric field measurements from Halley, Antarctica

    Science.gov (United States)

    Nicoll, Keri; Harrison, R. Giles

    2016-04-01

    Antarctica is a unique location for the study of atmospheric electricity. Not only is it one of the most pollutant free places on Earth, but its proximity to the south magnetic pole means that it is an ideal location to study the effects of solar variability on the atmospheric electric field. This is due to the reduced shielding effect of the geomagnetic field at the poles which leads to a greater flux of incoming Galactic Cosmic Rays (GCRs) as well as an increased probability of energetic particle precipitation from SEPs and relativistic electrons. To investigate such effects, two electric field mills of different design were installed at the British Antarctic Survey Halley base in February 2015 (75. 58 degrees south, 26.66 degrees west). Halley is situated on the Brunt Ice Shelf in the south east of the Weddell Sea and has snow cover all year round. Preliminary analysis has focused on selection of fair weather criteria using wind speed and visibility measurements which are vital to assess the effects of falling snow, blowing snow and freezing fog on the electric field measurements. When the effects of such adverse weather conditions are removed clear evidence of the characteristic Carnegie Curve diurnal cycle exists in the Halley electric field measurements (with a mean value of 50V/m and showing a 40% peak to peak variation in comparison to the 34% variation in the Carnegie data). Since the Carnegie Curve represents the variation in thunderstorm activity across the Earth, its presence in the Halley data confirms the presence of the global atmospheric electric circuit signal at Halley. The work presented here will discuss the details of the Halley electric field dataset, including the variability in the fair weather measurements, with a particular focus on magnetic field fluctuations.

  4. Rifts in the tectonic structure of East Antarctica

    Science.gov (United States)

    Golynsky, Dmitry; Golynsky, Alexander

    2010-05-01

    It was established that riftogenic and/or large linear tectonic structures in East Antarctica are distributed with a steady regularity with average distance between them about 650 km. All these structures (13) represent objects of undoubted scientific and practical interest and might be considered as immediate objects for conducting integrated geological and geophysical investigations. Analysis and generalization of the RADARSAT satellite system imagery and radio-echosounding survey data collected in the eastern part of Princess Elizabeth Land allow us to distinguish spatial boundaries of previously unknown continental rift system that was proposed to name Gaussberg (Golynsky & Golynsky, 2007). The rift is about 500 km long, and taking into consideration its western continuation in the form of short (fragmented) faults, may exceed 700 km. The elevation difference between depressions and horsts reaches 3 km. The rift structure consists of two sub-parallel depressions separated by segmented horst-like rises (escarpments). Deep depressions within the rift reach more than 800 m bsl near the West Ice Shelf and within the central graben occupied by the Phillipi Glacier. The width of the Gaussberg Rift system varies from 60 km in the south-western area to 150 km near the West Ice Shelf. The Gaussberg rift is considered as a part of the Lambert rift system, which has a complicated structure clearly recognized over both the continent and also its margin. The Gaussberg rift probably exploited a weak zone between the Proterozoic mobile belt and the Archaean Vestfold-Rauer cratonic block. Supposedly it initiated at the turn of Jurassic and Permian epoch or a little bit earlier as in case of the Lambert rift where the Permian graben formation with coal-bearing deposits predetermined the subsequent development of submeridional rift zone. The Gaussberg and also the Scott rift developed in the Queen Marie Land, may be considered as continuations of the Mahanadi Valley rift and

  5. Early Pliocene Warming in DVDP-11 Drillcore, Antarctica

    Science.gov (United States)

    Verhagen, C. M.; Passchier, S.

    2016-12-01

    A geochemical analysis of drilled core, DVDP-11, was conducted to determine surface weathering conditions, as well as calcium carbonate (CaCO3) productivity in order to investigate the extent of global warming during a previous time in Earths history. DVDP-11 was drilled in Taylor Valley, Antarctica at a high polar latitude of about 77º and the sediments analyzed here date to the early Pliocene. 16 samples from DVDP-11 were obtained from a depth range of 188.36-244.60 meters below sea floor (mbsf). The samples were ground and prepped for ICP-AES analysis. Major element concentrations were measured to determine the chemical index of alteration (CIA) using the formula: CIA=[Al2O3/(Al2O33+CaO+Na2O+K2O)] x 100, with CaO* designating CaO in the silicate fraction. Following ICP evaluation samples were then analyzed for CaCO3 content. Out of the total 16 samples, 8 samples ranging in depths between 223.7-238.6 mbsf, reacted with hydrochloric acid in the presence of foraminiferal carbonate and were tested for total weight percent CaCO3 using acid digestion. An age model was then constructed for these samples using the available magnetostratigraphy for DVDP-11. CIA results ranged from 45-54 and are consistent with glacial clays showing little weathering. However, two peaks were present of 53 and 54 at sample depths of 239.6 and 223.7 mbsf. Percent weight CaCO3 was measured to be high in some samples, in particular 9% at 239.6 mbsf and 6% at 227.3 mbsf. The portion of DVDP-11 analyzed for this report is within Chron C2n and C3n giving it an age range of 3.5-4.6 million years ago (Ma). While the average CIA values are typical of high latitudes, the acid digestion results indicate substantial warming, allowing the precipitation of CaCO3. This is an unexpected result to find at a high latitude where waters would be consistently too cold for CaCO3 to accumulate. The age range for the CaCO3 accumulation is between 4.5-4.6 Ma and aligns with peaks in CIA values representing a

  6. Energy Efficient Textile Drying

    OpenAIRE

    Brunzell, Lena

    2006-01-01

    Traditionally, textiles were dried outdoors with the wind and the sun enhancing the drying process. Tumble dryers offer a fast and convenient way of drying textiles independent of weather conditions. Tumble dryers, however, consume large amounts of electrical energy. Over 4 million tumble dryers are sold each year in Europe and a considerable amount of energy is used for drying of clothes. Increasing energy costs and the awareness about environmental problems related to a large energy use has...

  7. Valley blockade quantum switching in Silicon nanostructures.

    Science.gov (United States)

    Prati, Enrico

    2011-10-01

    In analogy to the Coulomb and the Pauli spin blockade, based on the electrostatic repulsion and the Pauli exclusion principle respectively, the concept of valley blockade in Silicon nanostructures is explored. The valley parity operator is defined. Valley blockade is determined by the parity conservation of valley composition eigenvectors in quantum transport. A Silicon quantum changeover switch based on a triple of donor quantum dots capable to separate electrons having opposite valley parity by virtue of the valley parity conservation is proposed. The quantum changeover switch represents a novel kind of hybrid quantum based classical logic device.

  8. Microbial trace fossils in Antarctica and the search for evidence of early life on Mars

    Science.gov (United States)

    Friedmann, E. Imre; Friedmann, Roseli O.

    1989-01-01

    It is possible to hypothesize that, if microbial life evolved on early Mars, fossil remnants of these organisms may be preserved on the surface. However, the cooling and drying of Mars probably resembled a cold desert and such an environment is not suitable for the process of fossilization. The frigid Ross Desert of Antarctica is probably the closest terrestrial analog to conditions that may have prevailed on the surface of the cooling and drying Mars. In this desert, cryptoendolithic microbial communities live in the airspaces of porous rocks, the last habitable niche in a hostile outside environment. The organisms produce characteristic chemical and physical changes in the rock substrate. Environmental changes (deterioration of conditions) may result in the death of the community. Although no cellular structures are fossilized, the conspicuous changes in the rock substrate are preserved as trace fossils. Likewise, microbial trace fossils (without cellular structures) may also be preserved on Mars: Discontinuities in structure or chemistry of the rock that are independent of physical or chemical gradients may be of biological origin. Ross Desert trace fossils can be used as a model for planning search strategies and for instrument design to find evidence of past Martian life.

  9. Inorganic chemistry, petrography and palaeobotany of Permian coals in the Prince Charles Mountains, East Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Holdgate, G.R. [School of Earth Sciences, The University of Melbourne, Victoria, 3010 (Australia); McLoughlin, S. [School of Natural Resource Sciences, Queensland University of Technology, P.O. Box 2434, Brisbane, Queensland 4001 (Australia); Drinnan, A.N. [School of Botany, The University of Melbourne, Victoria, 3010 (Australia); Finkelman, R.B.; Willett, J.C.; Chiehowsky, L.A. [U.S. Geological Survey, Mail Stop 956, Reston, VA 20092 (United States)

    2005-07-20

    Sampled outcrops of Permian coal seams of the Bainmedart Coal Measures in the Lambert Graben, eastern Antarctica, have been analysed for their proximates, ultimates, ash constituents and trace elements. A similar series of samples has been analysed for their principle maceral and microlithotype components and vitrinite reflectance. The coals are sub-bituminous to high volatile bituminous in rank; maturity increases markedly in southern exposures around Radok Lake where the oldest part of the succession is exposed and some strata have been intruded by mafic dykes and ultramafic sills. The coal ash is mostly silica and aluminium oxides, indicating that the mineral ash component is mostly quartz and various clay minerals. The ratio of silica to aluminium oxides appears to increase in an upward stratigraphic direction. The coal macerals include a relatively high liptinite content (mainly sporinite) that is significantly higher than for typical Gondwana coals. Greater degrees of weathering within the floodbasin/peat mire environments associated with climatic drying towards the end of the Permian might account for both preferential sporopollenin preservation and increased silica:aluminium oxide ratios up-section. Correlation of the coal maceral components to adjacent peninsula India coals indicates the closest comparative coals of similar age and rank occur within the Godavari Basin, rather then the Mahanadi Basin, which is traditionally interpreted to have been contiguous with the Lambert Graben before Gondwanan breakup. The petrological characteristics suggest that either previous interpretations of Palaeozoic basin alignments between Antarctica and India are incorrect, or that environmental settings and post-Permian burial histories of these basins were strongly independent of their tectonic juxtaposition. A permineralized peat bed within the succession reveals that the coals predominantly comprise wood- and leaf-rich debris derived from low-diversity forest

  10. Experimental culture of non-indigenous Juncus bufonius from King George Island, South Shetland Island, Antarctica

    Institute of Scientific and Technical Information of China (English)

    Marely Cuba-Díaz; Eduardo Fuentes; Mauricio Rondanelli-Reyes; Ángela Machuca

    2015-01-01

    Juncus bufonius L. (Juncaceae) is recognized by the US Department of Agriculture as a weed or invasive plant. Recently, we reported on J. bufonius L. var. bufonius associated with the native vascular plants Deschampsia antarctica and Colobanthus quitensis in the environs of the Polish Arctowski Station, King George Island, in the Maritime Antarctica. In this study, we evaluated the developmental stages and morphological characteristics of J. bufonius plants cultivated in controlled conditions beginning with seeds obtained from plants of the Antarctic population. Germination occurred at 3 weeks and the germination percentage was low (22.5%). The average time between the anthesis and seed formation was 7 weeks, similar to that reported for other species in the Juncaceae. According to data reported in the literature, Antarctic individuals were significantly smaller than their relatives growing in other conditions, except for the number of inflorescences. The morphological characteristics of a species vary according to its distribution and the edaphoclimatic environment where it occur; cosmopolitan plants shuch as J. bufonius also have reduced stature in cold environments. The low percentage germination may have been due to water availability in the plant chamber in which the study was conducted. J. bufonius is intolerant of dry environments, and once it suffers hydric stress its recovery is very low; thus, a moister environment could be beneficial. J. bufonius has become established amongst native vegetation near Arctowski Station and without careful control or eradication; it may have the potential to spread far beyond the site, as has happened with the alien grass Poa annua as human disturbance and climate warming increase.

  11. Application of a regional model to astronomical site testing in western Antarctica

    Science.gov (United States)

    Falvey, Mark; Rojo, Patricio M.

    2016-08-01

    The quality of ground-based astronomical observations is significantly affected by local atmospheric conditions, and the search for the best sites has led to the construction of observatories at increasingly remote locations, including recent initiatives on the high plateaus of East Antarctica where the calm, dry, and cloud-free conditions during winter are recognized as amongst the best in the world. Site selection is an important phase of any observatory development project, and candidate sites must be tested in the field with specialized equipment, a process both time consuming and costly. A potential means of screening site locations before embarking on field testing is through the use of regional climate models (RCMs). In this study, we describe the application of the Polar version of the Weather Research and Forecasting (WRF) model to the preliminary site suitability assessment of a hitherto unstudied region in West Antarctica. Numerical simulations with WRF were carried out for the winter (MJJA) of 2011 at 3- and 1-km spatial resolution over a region centered on the Ellsworth mountain range. Comparison with observations of surface wind speed and direction, temperature, and specific humidity at nine automatic weather stations indicates that the model performed well in capturing the mean values and time variability of these variables. Credible features revealed by the model includes zones of high winds over the southernmost part of the Ellsworth Mountains, a deep thermal inversion over the Ronne-Fincher Ice Shelf, and strong west to east moisture gradient across the entire study area. Comparison of simulated cloud fraction with a CALIPSO spacebourne Lidar climatology indicates that the model may underestimate cloud occurrence, a problem that has been noted in previous studies. A simple scoring system was applied to reveal the most promising locations. The results of this study indicate that the WRF model is capable of providing useful guidance during the

  12. A comparison of coincident GRACE and ICESat data over Antarctica

    NARCIS (Netherlands)

    Gunter, B.; Urban, T.; Riva, R.E.M.; Helsen, M.M.; Harpold, R.; Poole, S.; Nagel, P.; Schutz, B.; Tapley, B.

    2009-01-01

    In this study, we present a comparison of coincident GRACE and ICESat data over Antarctica. The analysis focused on the secular changes over a 4-year period spanning from 2003 to 2007, using the recently reprocessed and publicly available data sets for both missions. The results show that the two in

  13. P-band radar ice sounding in Antarctica

    DEFF Research Database (Denmark)

    Dall, Jørgen; Kusk, Anders; Kristensen, Steen Savstrup

    2012-01-01

    In February 2011, the Polarimetric Airborne Radar Ice Sounder (POLARIS) was flown in Antarctica in order to assess the feasibility of a potential space-based radar ice sounding mission. The campaign has demonstrated that the basal return is detectable in areas with up to 3 km thick cold ice...

  14. DOMECair: An Airborne Campaign in Antarctica Supporting SMOS Calibration

    DEFF Research Database (Denmark)

    Skou, Niels; Kristensen, Steen Savstrup; Søbjærg, Sten Schmidl

    2013-01-01

    In search for a stable, well characterized terrestrial calibration target for SMOS, an airborne campaign was carried out in January 2013 over the Dome C area of Antarctica, and the surface was measured by an L-band radiometer. The focus was on homogeneity, and an area of 350 × 350 km around...

  15. The Twelfth Indian Scientific Expedition to Antarctica: Events and achievements

    Digital Repository Service at National Institute of Oceanography (India)

    Dhargalkar, V

    Delhi and Dr. B.N. Desai, Director, National Institute of Oceanography, Goa, families of the expedition members and friends. This was the smallest team M.V. Thuleland ever carried to Antarctica. On very next day of sailing the members were briefed about...

  16. Abrupt climate warming in East Antarctica during the early Holocene

    NARCIS (Netherlands)

    Cremer, H.; Heiri, O.; Wagner, B.; Wagner-Cremer, F.

    2007-01-01

    We report a centennial-scale warming event between 8600 and 8400 cal BP from Amery Oasis, East Antarctica, that is documented by the geochemical record in a lacustrine sediment sequence. The organic carbon content, the C/S ratio, and the sedimentation rate in this core have distinctly elevated value

  17. An evolutionary insight into Newcastle disease viruses isolated in Antarctica.

    Science.gov (United States)

    Soñora, Martin; Moreno, Pilar; Echeverría, Natalia; Fischer, Sabrina; Comas, Victoria; Fajardo, Alvaro; Cristina, Juan

    2015-08-01

    The disease caused by Newcastle disease virus (NDV) is a severe threat to the poultry industry worldwide. Recently, NDV has been isolated in the Antarctic region. Detailed studies on the mode of evolution of NDV strains isolated worldwide are relevant for our understanding of the evolutionary history of NDV. For this reason, we have performed Bayesian coalescent analysis of NDV strains isolated in Antarctica to study evolutionary rates, population dynamics, and patterns of evolution. Analysis of F protein cleavage-site sequences of NDV isolates from Antarctica suggested that these strains are lentogenic. Strains isolated in Antarctica and genotype I reference strain Ulster/67 diverged from ancestors that existed around 1958. The time of the most recent common ancestor (MRCA) was established to be around 1883 for all class II viruses. A mean rate of evolution of 1.78 × 10(-3) substitutions per site per year (s/s/y) was obtained for the F gene sequences of NDV strains examined in this study. A Bayesian skyline plot indicated a decline in NDV population size in the last 25 years. The results are discussed in terms of the possible role of Antarctica in emerging or re-emerging viruses and the evolution of NDV populations worldwide.

  18. Ross Ice Shelf and the Queen Maude Mounains, Antarctica

    Science.gov (United States)

    1991-01-01

    Part of the Ross Ice Shelf and the Queen Maude Mounains of Antarctica (55.5N, 178.0W) are in the background of this scene, oriented toward the south. Low stratocumulus clouds are predominant throughout most of the scene.

  19. Origin(s) of Antarctica's Wilkes subglacial basin

    NARCIS (Netherlands)

    Weihaupt, J.G.; Van der Hoeven, F.G.; Lorius, C.; Chambers, F.B.

    2013-01-01

    The Wilkes Subglacial Basin (WSB), the largest subglacial basin in East Antarctica, is a topographic depression of continental proportions that lies beneath the East Antarctic continental ice sheet. Discovered by the US Victoria Land Traverse 1959–60, the origin of the WSB and the influence of palae

  20. Surface and snowdrift sublimation at Princess Elisabeth station, East Antarctica

    NARCIS (Netherlands)

    Thiery, W.; Gorodetskaya, I.V.; Bintanja, R.; van Lipzig, N.P.M.; van den Broeke, M.R.; Reijmer, C.H.; Kuipers Munneke, P.

    2012-01-01

    In the near-coastal regions of Antarctica, a significant fraction of the snow precipitating onto the surface is removed again through sublimation – either directly from the surface or from drifting snow particles. Meteorological observations from an Automatic Weather Station (AWS) near the Belgian r

  1. Antarctica: Arena for South American Cooperation or Conflict.

    Science.gov (United States)

    Child, Jack

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

  2. Triassic leech cocoon from Antarctica contains fossil bell animal

    DEFF Research Database (Denmark)

    Bomfleur, Benjamin; Kerp, Hans; Taylor, Thomas N.

    2012-01-01

    , exceptional fossil deposits that preserve soft-bodied organisms provide a rare glimpse of the true biodiversity during past periods of Earth history. We here present an extraordinary find of a fossil ciliate that is encased inside the wall layer of a more than 200 Ma leech cocoon from Antarctica...

  3. Mass Casualty Incident Response and Aeromedical Evacuation in Antarctica

    Directory of Open Access Journals (Sweden)

    Mills, Christopher N

    2011-02-01

    Full Text Available Antarctica is one of the most remote regions on Earth. Mass casualty incident (MCI responses in Antarctica are prone to complications from multiple environmental and operational challenges. This review of the current status of MCI risks and response strategies for Antarctica focuses on aeromedical evacuation, a critical component of many possible MCI scenarios. Extreme cold and weather, a lack of medical resources and a multitude of disparate international bases all exert unique demands on MCI response planning. Increasing cruise ship traffic is also escalating the risk of MCI occurrence. To be successful, MCI response must be well coordinated and undertaken by trained rescuers, especially in the setting of Antarctica. Helicopter rescue or aeromedical evacuation of victims to off-continent facilities may be necessary. Currently, military forces have the greatest capacity for mass air evacuation. Specific risks that are likely to occur include structure collapses, vehicle incapacitations, vehicle crashes and fires. All of these events pose concomitant risks of hypothermia among both victims and rescuers. Antarctica’s unique environment requires flexible yet robust MCI response planning among the many entities in operation on the continent. [West J Emerg Med. 2011;12(1:37-42.

  4. Titan's fluvial valleys: Morphology, distribution, and spectral properties

    Science.gov (United States)

    Langhans, M.H.; Jaumann, R.; Stephan, K.; Brown, R.H.; Buratti, B.J.; Clark, R.N.; Baines, K.H.; Nicholson, P.D.; Lorenz, R.D.; Soderblom, L.A.; Soderblom, J.M.; Sotin, C.; Barnes, J.W.; Nelson, R.

    2012-01-01

    Titan's fluvial channels have been investigated based on data obtained by the Synthetic Aperture Radar (SAR) instrument and the Visible and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft. In this paper, a database of fluvial features is created based on radar-SAR data aiming to unveil the distribution and the morphologic and spectral characteristics of valleys on Titan on a global scale. It will also study the spatial relations between fluvial valleys and Titan's geologic units and spectral surface units which have become accessible thanks to Cassini-VIMS data. Several distinct morphologic types of fluvial valleys can be discerned by SAR-images. Dendritic valley networks appear to have much in common with terrestrial dendritic systems owing to a hierarchical and tree-shaped arrangement of the tributaries which is indicative of an origin from precipitation. Dry valleys constitute another class of valleys resembling terrestrial wadis, an indication of episodic and strong flow events. Other valley types, such as putative canyons, cannot be correlated with rainfall based on their morphology alone, since it cannot be ruled out that they may have originated from volcanic/tectonic action or groundwater sapping. Highly developed and complex fluvial networks with channel lengths of up to 1200 km and widths of up to 10 km are concentrated only at a few locations whereas single valleys are scattered over all latitudes. Fluvial valleys are frequently found in mountainous areas. Some terrains, such as equatorial dune fields and undifferentiated plains at mid-latitudes, are almost entirely free of valleys. Spectrally, fluvial terrains are often characterized by a high reflectance in each of Titan's atmospheric windows, as most of them are located on Titan's bright 'continents'. Nevertheless, valleys are spatially associated with a surface unit appearing blue due to its higher reflection at 1.3??m in a VIMS false color RGB composite with R: 1.59/1.27??m, G: 2

  5. 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.

  6. 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.

  7. Dry vacuum pumps

    Science.gov (United States)

    Sibuet, R.

    2008-05-01

    For decades and for ultimate pressure below 1 mbar, oil-sealed Rotary Vane Pumps have been the most popular solution for a wide range of vacuum applications. In the late 80ies, Semiconductor Industry has initiated the development of the first dry roughing pumps. Today SC applications are only using dry pumps and dry pumping packages. Since that time, pumps manufacturers have developed dry vacuum pumps technologies in order to make them attractive for other applications. The trend to replace lubricated pumps by dry pumps is now spreading over many other market segments. For the Semiconductor Industry, it has been quite easy to understand the benefits of dry pumps, in terms of Cost of Ownership, process contamination and up-time. In this paper, Technology of Dry pumps, its application in R&D/industries, merits over conventional pumps and future growth scope will be discussed.

  8. Seismic Constraints on the Mantle Viscosity Structure beneath Antarctica

    Science.gov (United States)

    Wiens, Douglas; Heeszel, David; Aster, Richard; Nyblade, Andrew; Wilson, Terry

    2015-04-01

    Lateral variations in upper mantle viscosity structure can have first order effects on glacial isostatic adjustment. These variations are expected to be particularly large for the Antarctic continent because of the stark geological contrast between ancient cratonic and recent tectonically active terrains in East and West Antarctica, respectively. A large misfit between observed and predicted GPS rates for West Antarctica probably results in part from the use of a laterally uniform viscosity structure. Although not linked by a simple relationship, mantle seismic velocities can provide important constraints on mantle viscosity structure, as they are both largely controlled by temperature and water content. Recent higher resolution seismic models for the Antarctic mantle, derived from data acquired by new seismic stations deployed in the AGAP/GAMSEIS and ANET/POLENET projects, offer the opportunity to use the seismic velocity structure to place new constraints on the viscosity of the Antarctic upper mantle. We use an Antarctic shear wave velocity model derived from array analysis of Rayleigh wave phase velocities [Heeszel et al, in prep] and examine a variety of methodologies for relating seismic, thermal and rheological parameters to compute a suite of viscosity models for the Antarctic mantle. A wide variety of viscosity structures can be derived using various assumptions, but they share several robust common elements. There is a viscosity contrast of at least two orders of magnitude between East and West Antarctica at depths of 80-250 km, reflecting the boundary between cold cratonic lithosphere in East Antarctica and warm upper mantle in West Antarctica. The region beneath the Ellsworth-Whitmore Mtns and extending to the Pensacola Mtns. shows intermediate viscosity between the extremes of East and West Antarctica. There are also significant variations between different parts of West Antarctica, with the lowest viscosity occurring beneath the Marie Byrd Land (MBL

  9. Small Glaciofluvial Valleys on Amazonian Mars

    Science.gov (United States)

    Fassett, C.; Dickson, J.; Head, J. W.; Levy, J. S.; Marchant, D. R.

    2009-12-01

    We present new observations of small valleys associated with glacial features in the Martian mid-latitudes, based on a survey of images from the Context Camera (CTX) on the Mars Reconnaissance Orbiter. These valleys are small (~50-400 m wide) and short (mechanism most likely to explain their origin is top-down melting of these cold-based glaciers. Some valleys have associated sedimentary deposits (small fans) (e.g., Fig. 1). Both stratigraphic relations and crater counting constrain most such valleys to the Amazonian period. The observed glaciofluvial valleys are typically on slopes of P16_007256_1383). The valley begins in a small alcove, where remnant glacial materials are now ~1 km from the valley head. The valley is ~5.5 km long, has an average slope of 5°, and terminates in an elongate fan.

  10. EPA Region 1 - Valley Depth in Meters

    Data.gov (United States)

    U.S. Environmental Protection Agency — Raster of the Depth in meters of EPA-delimited Valleys in Region 1. Valleys (areas that are lower than their neighbors) were extracted from a Digital Elevation Model...

  11. 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

  12. 27 CFR 9.57 - Green Valley of Russian River Valley.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Green Valley of Russian River Valley. 9.57 Section 9.57 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE... Areas § 9.57 Green Valley of Russian River Valley. (a) Name. The name of the viticultural area...

  13. 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...

  14. 27 CFR 9.23 - Napa Valley.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Napa Valley. 9.23 Section... THE TREASURY LIQUORS AMERICAN VITICULTURAL AREAS Approved American Viticultural Areas § 9.23 Napa Valley. (a) Name. The name of the viticultural area described in this section is “Napa Valley.”...

  15. Valley Singularities and Baryon Number Violation

    CERN Document Server

    Provero, P

    1994-01-01

    We consider the valley--method computation of the inclusive cross section of baryon number violating processes in the Standard Model. We show that any physically correct model of the valley action should present a singularity in the saddle point valley parameters as functions of the energy of the process. This singularity prevents the saddle point configuration from collapsing into the perturbative vacuum.

  16. 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.

  17. Atmospheric turbidity over Kathmandu valley

    Science.gov (United States)

    Sapkota, Balkrishna; Dhaubhadel, Rajan

    The atmosphere of Kathmandu Valley has been investigated by using Sunphotometer and Nephelometer during the pre-monsoon period of 1999. The atmospheric turbidity parameters (extinction coefficient for 500 nm wavelength τAG and Angstrom coefficient β) are found high in the morning and show decreasing trends from morning to late afternoon on average. Vertical dispersion of pollutants and increasing pollutant flushing rate by increasing wind speed from morning to late afternoon is the cause for this decreasing trend of turbidity over the valley. Being surrounded by high hills all around the valley, horizontal exit of pollutants without vertical dispersion is not possible. The scattering coefficient bscat of aerosols in ground level troposphere is also found high in the morning, which decreases and becomes minimum during afternoon. During late afternoon, bscat again shows a slightly increasing trend. The reason is the increasing vehicular emission during late afternoon rush period. The average values of Angstrom exponent α, β, τAG and bscat are found to be 0.624±0.023, 0.299±0.009, 0.602±0.022 and 0.353±0.014 km -1, respectively. About 76.8% of the observed values of β lie above 0.2 indicating heavy particulate pollution in the valley. A comparison of observed values of turbidity parameters with other major cities of the world shows that Kathmandu is as polluted as cities like Jakarta, Kansas, Beijing, Vienna, etc.

  18. 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.

  19. Post-depositional modification of NO-3 in snow layers at EastAntarctica and at the headwater of ürumqi River

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Acidic species, such as Nitrate, in polar snow and firn layers are “reversibly” deposited, and are sufficiently volatile to undergo significant postdepositional exchange between snow/firn and the atmosphere. Through comparison of the snowpit and snowpack nitrate concentrations from central East Antarctica and the headwater of ürumqi River, we conclude that the nitrate peaks in the uppermost surface snow layers in central Antarctica are not related to an atmospheric signal and must account for post-depositional effects. Such effects, however, are not found in the surface snowpack nitrate profiles from the headwater of ürumqi River. Two reasons may account for the post-depositional difference. At first, nitrate in the polar snow and firn layers appears to be hydrated ion, which can be taken up by the atmosphere, while at the headwater of ürumqi River it seems mainly as mineral ion, which assembles the behavior of aerosol-derived species that are “irreversibly” deposited and do not undergo significant post-depositional exchange with the atmosphere. Secondly, the chemical features of the snow and ice on the Antarctica are mainly determined by wet deposition, to the contrary, dry deposition is more significant at the headwater of lUrumqi River than that on the East Antarctic Plateau.

  20. The Central Valley Hydrologic Model

    Science.gov (United States)

    Faunt, C.; Belitz, K.; Hanson, R. T.

    2009-12-01

    Historically, California’s Central Valley has been one of the most productive agricultural regions in the world. The Central Valley also is rapidly becoming an important area for California’s expanding urban population. In response to this competition for water, a number of water-related issues have gained prominence: conjunctive use, artificial recharge, hydrologic implications of land-use change, subsidence, and effects of climate variability. To provide information to stakeholders addressing these issues, the USGS made a detailed assessment of the Central Valley aquifer system that includes the present status of water resources and how these resources have changed over time. The principal product of this assessment is a tool, referred to as the Central Valley Hydrologic Model (CVHM), that simulates surface-water flows, groundwater flows, and land subsidence in response to stresses from human uses and from climate variability throughout the entire Central Valley. The CVHM utilizes MODFLOW combined with a new tool called “Farm Process” to simulate groundwater and surface-water flow, irrigated agriculture, land subsidence, and other key processes in the Central Valley on a monthly basis. This model was discretized horizontally into 20,000 1-mi2 cells and vertically into 10 layers ranging in thickness from 50 feet at the land surface to 750 feet at depth. A texture model constructed by using data from more than 8,500 drillers’ logs was used to estimate hydraulic properties. Unmetered pumpage and surface-water deliveries for 21 water-balance regions were simulated with the Farm Process. Model results indicate that human activities, predominately surface-water deliveries and groundwater pumping for irrigated agriculture, have dramatically influenced the hydrology of the Central Valley. These human activities have increased flow though the aquifer system by about a factor of six compared to pre-development conditions. The simulated hydrology reflects spatial

  1. Breakup of the Larsen Ice Shelf, Antarctica

    Science.gov (United States)

    2002-01-01

    Recent Moderate-resolution Imaging Spectroradiometer (MODIS) satellite imagery analyzed at the University of Colorado's National Snow and Ice Data Center revealed that the northern section of the Larsen B ice shelf, a large floating ice mass on the eastern side of the Antarctic Peninsula, has shattered and separated from the continent. This particular image was taken on March 5, 2002. The shattered ice formed a plume of thousands of icebergs adrift in the Weddell Sea. A total of about 3,250 square kilometers of shelf area disintegrated in a 35-day period beginning on January 31, 2002. Over the last five years, the shelf has lost a total of 5,700 square kilometers and is now about 40 percent the size of its previous minimum stable extent. Ice shelves are thick plates of ice, fed by glaciers, that float on the ocean around much of Antarctica. The Larsen B shelf was about 220 meters thick. Based on studies of ice flow and sediment thickness beneath the ice shelf, scientists believe that it existed for at least 400 years prior to this event and likely existed since the end of the last major glaciation 12,000 years ago. For reference, the area lost in this most recent event dwarfs Rhode Island (2,717 square kilometers) in size. In terms of volume, the amount of ice released in this short time is 720 billion tons--enough ice for about 12 trillion 10-kilogram bags. This is the largest single event in a series of retreats by ice shelves along the peninsula over the last 30 years. The retreats are attributed to a strong climate warming in the region. The rate of warming is approximately 0.5 degrees Celsius per decade, and the trend has been present since at least the late 1940s. Overall in the peninsula, the extent of seven ice shelves has declined by a total of about 13,500 square kilometers since 1974. This value excludes areas that would be expected to calve under stable conditions. Ted Scambos, a researcher with the National Snow and Ice Data Center (NSIDC) at

  2. Ambient Dried Aerogels

    Science.gov (United States)

    Jones, Steven M.; Paik, Jong-Ah

    2013-01-01

    A method has been developed for creating aerogel using normal pressure and ambient temperatures. All spacecraft, satellites, and landers require the use of thermal insulation due to the extreme environments encountered in space and on extraterrestrial bodies. Ambient dried aerogels introduce the possibility of using aerogel as thermal insulation in a wide variety of instances where supercritically dried aerogels cannot be used. More specifically, thermoelectric devices can use ambient dried aerogel, where the advantages are in situ production using the cast-in ability of an aerogel. Previously, aerogels required supercritical conditions (high temperature and high pressure) to be dried. Ambient dried aerogels can be dried at room temperature and pressure. This allows many materials, such as plastics and certain metal alloys that cannot survive supercritical conditions, to be directly immersed in liquid aerogel precursor and then encapsulated in the final, dried aerogel. Additionally, the metalized Mylar films that could not survive the previous methods of making aerogels can survive the ambient drying technique, thus making multilayer insulation (MLI) materials possible. This results in lighter insulation material as well. Because this innovation does not require high-temperature or high-pressure drying, ambient dried aerogels are much less expensive to produce. The equipment needed to conduct supercritical drying costs many tens of thousands of dollars, and has associated running expenses for power, pressurized gasses, and maintenance. The ambient drying process also expands the size of the pieces of aerogel that can be made because a high-temperature, high-pressure system typically has internal dimensions of up to 30 cm in diameter and 60 cm in height. In the case of this innovation, the only limitation on the size of the aerogels produced would be in the ability of the solvent in the wet gel to escape from the gel network.

  3. Ocean Dynamics: Vietnam DRI

    Science.gov (United States)

    2014-09-30

    Dynamics: Vietnam DRI Robert Pinkel Marine Physical Laboratory Scripps Institution of Oceanography La Jolla California 92093-0213 Phone: (858) 534...DATES COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE Ocean Dynamics: Vietnam DRI 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM...cycle.. The Thorpe-scale estimates are local to Site III. South China Sea Process Cruise 2014 Under Vietnam DRI funding, Researcher Drew Lucas

  4. Mistletoes and epiphytic lichens contribute to litter input in Nothofagus antarctica forests

    Science.gov (United States)

    Soler, Rosina; Pastur, Guillermo Martínez; Lencinas, María Vanessa; Peri, Pablo Luis

    2015-10-01

    Litter input is one of the key components that define nutrient cycling in forests and the majority of studies only consider the tree components of litterfall. However, epiphytic species can play a crucial role in litter input throughout the growing season. This work evaluates changes in litter production by mistletoe (Misodendrum sp.) and epiphytic lichen (Usnea sp.), related to crown cover in mature unmanaged, second-growth and managed (thinned for silvopastoral use) forests in Tierra del Fuego (Argentina). We used plastic traps to collect litterfall biomass from trees, lichens and mistletoes on a monthly basis over three consecutive years. Tree litter was considerable during autumn (March to May), which is typical of Nothofagus deciduous species in the Southern hemisphere. In contrast, peak litterfall from mistletoes and lichens occurred during spring and summer seasons. Tree litter (1954-3398 kg dry matter ha-1 year-1) was correlated with crown cover gradient being highest in second-growth forests and lowest in thinned sites. While litter input from mistletoes did not vary among forest types (307-333 kg dry matter ha-1 year-1), lichen litter (11-40 kg dry matter ha-1 year-1) was higher in unmanaged and thinned mature forests despite differences in tree crown cover. Contrary to what we expected, the management practices investigated here did not affect the biomass of canopy communities compared to unmanaged mature forests. Mistletoes and lichens significantly increased the spatial (forest type) and temporal complexity (extended period of falling) of litterfall in Nothofagus antarctica forests. This study provides a starting point to understand the ecological relevance of canopy communities in the Patagonian forests of southern Argentina.

  5. Conference report: 2nd Medicon Valley Inhalation Symposium.

    Science.gov (United States)

    Lastow, Orest

    2014-02-01

    2nd Medicon Valley Inhalation Symposium 16 October 2013, Lund, Sweden The 2nd Medicon Valley Inhalation Symposium was arranged by the Medicon Valley Inhalation Consortium. It was held at the Medicon Village, which is the former AstraZeneca site in Lund, Sweden. It was a 1 day symposium focused on inhaled drug delivery and inhalation product development. 120 delegates listened to 11 speakers. The program was organized to follow the value chain of an inhalation product development. This year there was a focus on inhaled biomolecules. The inhaled delivery of insulin was covered by two presentations and a panel discussion. The future of inhaled drug delivery was discussed together with an overview of the current market situation. Two of the inhalation platforms, capsule inhalers and metered-dose inhalers, were discussed in terms of the present situation and the future opportunities. Much focus was on the regulatory and intellectual aspects of developing inhalation products. The manufacturing of a dry powder inhaler requires precision filling of powder, and the various techniques were presented. The benefits of nebulization and nasal delivery were illustrated with some case studies and examples. The eternal challenge of poor compliance was addressed from an industrial design perspective and some new approaches were introduced.

  6. 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

  7. Expressed sequence tag analysis of Antarctic hairgrass Deschampsia antarctica from King George Island, Antarctica.

    Science.gov (United States)

    Lee, Hyoungseok; Cho, Hyun Hee; Kim, Il-Chan; Yim, Joung Han; Lee, Hong Kum; Lee, Yoo Kyung

    2008-04-30

    Deschampsia antarctica is the only monocot that thrives in the tough conditions of the Antarctic region. It is an invaluable resource for the identification of genes associated with tolerance to various environmental pressures. In order to identify genes that are differentially regulated between greenhouse-grown and Antarctic field-grown plants, we initiated a detailed gene expression analysis. Antarctic plants were collected and greenhouse plants served as controls. Two different cDNA libraries were constructed with these plants. A total of 2,112 cDNA clones was sequenced and grouped into 1,199 unigene clusters consisting of 243 consensus and 956 singleton sequences. Using similarity searches against several public databases, we constructed a functional classification of the ESTs into categories such as genes related to responses to stimuli, as well as photosynthesis and metabolism. Real-time PCR analysis of various stress responsive genes revealed different patterns of regulation in the different environments, suggesting that these genes are involved in responses to specific environmental factors.

  8. Distribution of ice thickness and subglacial topography of the “Chinese Wall” around Kunlun Station, East Antarctica

    Institute of Scientific and Technical Information of China (English)

    Cui Xiang-Bin; Sun Bo; Su Xiao-Gang; Guo Jing-Xue

    2016-01-01

    As fundamental parameters of the Antarctic Ice Sheet, ice thickness and subglacial topography are critical factors for studying the basal conditions and mass balance in Antarctica. During CHINARE 24 (the 24th Chinese National Antarctic Research Expedition, 2007/08), the research team used a deep ice-penetrating radar system to measure the ice thickness and subglacial topography of the “Chinese Wall” around Kunlun Station, East Antarctica. Preliminary results show that the ice thickness varies mostly from 1600 m to 2800 m along the “Chinese Wall”, with the thickest ice being 3444 m, and the thinnest ice 1255 m. The average bedrock elevation is 1722 m, while the minimum is just 604 m. Compared with the northern side of the ice divide, the ice thickness is a little greater and the subglacial topography lower on the southern side, which is also characterized by four deep valleys. We found no basal freeze-on ice in the Gamburtsev Subglacial Mountains area, subglacial lakes, or water bodies along the “Chinese Wall”. Ice thickness and subglacial topography data extracted from the Bedmap 2 database along the “Chinese Wall” are consistent with our results, but their resolution and accuracy are very limited in areas where the bedrock fl uctuates intensely. The distribution of ice thickness and subglacial topography detected by ice-penetrating radar clarifi es the features of the ice sheet in this “inaccessible” region. These results will help to advance the study of ice sheet dynamics and the determination of future locations of the GSM’s geological and deep ice core drilling sites in the Dome A region.

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

    Science.gov (United States)

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

    2017-05-01

    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.

  10. 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 ... Eye Treatment What Is Dry Eye? Leer en Español: ¿Qué Es el Ojo Seco? Written By: Kierstan ...

  11. Climate change and agricultural transformation in the Oaxaca Valley, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Dilley, F.B.

    1993-01-01

    The Valley of Oaxaca, a semi-arid region in the central highlands of southern Mexico, provides a case study through which to develop a methodology for climate change impact assessment. The causes and impacts of climate change originate in dialectic processes within a nexus of inter-dependent social, technical, environmental, cultural and academic production relations. Agriculture is the most important economic activity in the Valley, and rain-fed maize the most important crop. Harvest failures from droughts occur one year in four. Annual rainfall varies with large-scale convection of water vapor transported from the Pacific and Gulf of Mexico during summer, upper-air disturbances caused by hurricanes and El Ninos. Variations in maize yields and losses have roughly moisture availability during August. Yields and losses can be predicted using precipitation during this time, or directly from atmospheric circulation. Contemporary agriculture in the Valley of Oaxaca has both traditional and modern sectors, of which both may appear within individual communities and households. The traditional sector consists of semi-autonomous rural communities using traditional technology for subsistence farming. The modern sector uses tractors, irrigation pumps, agricultural chemicals and hybrid seeds to produce cash crops and dairy products. The evidence for climate change in the Valley is ambiguous and contradictory. Under wet or dry scenarios, climate change affects the rate and pathway of the absorption of Oaxaca's traditional rural communities into the wage labor market of the larger capitalist system. Increased moisture availability would raise land productivity, promoting cash cropping and development of the modern market-oriented agricultural sector and leading to land consolidation and rural-to-urban migration. Decreased moisture availability would inhibit cash-cropping but also lead to rural-to-urban migration due to decreased land productivity.

  12. First time-series optical photometry from Antarctica

    CERN Document Server

    Strassmeier, K G; Granzer, T; Tosti, G; DiVarano, I; Savanov, I; Bagaglia, M; Castellini, S; Mancini, A; Nucciarelli, G; Straniero, O; Distefano, E; Messina, S; Cutispoto, G

    2008-01-01

    Beating the Earth's day-night cycle is mandatory for long and continuous time-series photometry and had been achieved with either large ground-based networks of observatories at different geographic longitudes or when conducted from space. A third possibility is offered by a polar location with astronomically-qualified site characteristics. Aims. In this paper, we present the first scientific stellar time-series optical photometry from Dome C in Antarctica and analyze approximately 13,000 CCD frames taken in July 2007. We conclude that high-precision CCD photometry with exceptional time coverage and cadence can be obtained at Dome C in Antarctica and be successfully used for time-series astrophysics.

  13. Synchronous climate changes in Antarctica and the North Atlantic

    Science.gov (United States)

    Steig, E.J.; Brook, E.J.; White, J.W.C.; Sucher, C.M.; Bender, M.L.; Lehman, S.J.; Morse, D.L.; Waddington, E.D.; Clow, G.D.

    1998-01-01

    Central Greenland ice cores provide evidence of abrupt changes in climate over the past 100,000 years. Many of these changes have also been identified in sedimentary and geochemical signatures in deep-sea sediment cores from the North Atlantic, confirming the link between millennial-scale climate variability and ocean thermohaline circulation. It is shown here that two of the most prominent North Atlantic events - the rapid warming that makes the end of the last glacial period and the Bolling/Allerod-Younger Dryas oscillation - are also recorded in an ice core from Taylor Dome, in the western Ross Sea sector of Antarctica. This result contrasts with evidence from ice cores in other regions of Antarctica, which show an asynchronous response between the Northern and Southern Hemispheres.

  14. The establishment of GPS network in Grove Mountains, East Antarctica

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The Grove Mountains are located in Princess Elizabeth Land, East Antarctica, extending from 72° to 73°S latitude and 73° to 76°E longitude, covering approximately 8000 km2 areas. During the 2002/2003 austral summer season, the 19th CHINARE (Chinese National Antarctic Research Expedition) carried out the third expedition in Grove Mountains, East Antarctica. The Geodetic network was established, which can provide ground control for the satellite image map for the multi-discipline expedition in the Grove Mountains where seven permanent GPS benchmarks were set up supported by the helicopter and snow vehicles. All GPS sites besides Z001 were observed at least for one hour using the dual frequencies Trimble 4000ssi GPS receivers. The data were processed by the comprehensive GPS analysis package-GAMIT/GLOBK and the precision is good enough to satisfy with the acquirement of satellite mapping in this area.

  15. Dry imaging cameras

    Directory of Open Access Journals (Sweden)

    I K Indrajit

    2011-01-01

    Full Text Available Dry imaging cameras are important hard copy devices in radiology. Using dry imaging camera, multiformat images of digital modalities in radiology are created from a sealed unit of unexposed films. The functioning of a modern dry camera, involves a blend of concurrent processes, in areas of diverse sciences like computers, mechanics, thermal, optics, electricity and radiography. Broadly, hard copy devices are classified as laser and non laser based technology. When compared with the working knowledge and technical awareness of different modalities in radiology, the understanding of a dry imaging camera is often superficial and neglected. To fill this void, this article outlines the key features of a modern dry camera and its important issues that impact radiology workflow.

  16. VLF wave injection experiments from Siple Station, Antarctica

    OpenAIRE

    R.A., Helliwell

    1987-01-01

    The background of VLF wave-particle experiments from Siple Station, Antarctica, including wave-induced precipitation is briefly reviewed. Single frequency ducted signals that exceed a certain 'threshold' intensity are observed at the conjugate point (Roberval, Quebec) to be amplified 30-50dB, with temporal growth rates of 30-200dB/s. Following saturation, variable frequency emissions are triggered. When a second signal is added to the first, with a frequency spacing Df

  17. The conquest of Antarctica; A la conquista de la Antartida

    Energy Technology Data Exchange (ETDEWEB)

    Tristan, R. M.

    2015-07-01

    The information obtained in the more than 15 projects designed for the XXVIII campaign to Antarctica, and in the they involved a total of 80 researchers, will serve to learn more about terrestrial magnetism, changes occurring in the climate, the behavior of the volcanoes, the evolution of the glaciers, the rate of thaw, the weather variations, characteristics of the lichens, the progress of pollution... Even know the past that remains frozen under the ice to predict what might happen in the future. (Author)

  18. Victoria Land, Ross Sea, and Ross Ice Shelf, Antarctica

    Science.gov (United States)

    2002-01-01

    On December 19, 2001, MODIS acquired data that produced this image of Antarctica's Victoria Land, Ross Ice Shelf, and the Ross Sea. The coastline that runs up and down along the left side of the image denotes where Victoria Land (left) meets the Ross Ice Shelf (right). The Ross Ice Shelf is the world's largest floating body of ice, approximately the same size as France. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  19. Transiting planet candidates with ASTEP 400 at Dome C, Antarctica

    Science.gov (United States)

    Mékarnia, D.; Guillot, T.; Rivet, J.-P.; Schmider, F.-X.; Abe, L.; Gonçalves, I.; Agabi, A.; Crouzet, N.; Fruth, T.; Barbieri, M.; Bayliss, D. D. R.; Zhou, G.; Aristidi, E.; Szulagyi, J.; Daban, J.-B.; Fanteï-Caujolle, Y.; Gouvret, C.; Erikson, A.; Rauer, H.; Bouchy, F.; Gerakis, J.; Bouchez, G.

    2016-11-01

    ASTEP 400, the main instrument of the ASTEP (Antarctica Search for Transiting ExoPlanets) programme, is a 40 cm telescope, designed to withstand the harsh conditions in Antarctica, achieving a photometric accuracy of a fraction of millimagnitude on hourly time-scales for planet-hosting southern bright (R ˜ 12 mag) stars. We review the performances of this instrument, describe its operating conditions, and present results from the analysis of observations obtained during its first three years (2010-2012) of operation, before its repatriation in 2014. During this time, we observed a total of 22 stellar fields (1° × 1° field of view). Each field, in which we measured stars up to magnitude R = 18 mag, was observed continuously during ˜7 to ˜30 d. More than 200 000 frames were recorded and 310 000 stars processed, using an implementation of the optimal image subtraction photometry algorithm. We found 43 planetary transit candidates. 20 of these candidates were observed using spectroscopic follow-ups including four targets classified as good planet candidates. Our results demonstrate that accurate near-continuous photometric observations are achievable from the Concordia station at Dome C in Antarctica, even if we were not able to reach the nominal photometric precision of the instrument. We conducted a correlation analysis between the rms noise and a large number of external parameters and found that source of the ˜1 mmag correlated noise is not obvious and does not depend on a single parameter. However, our analysis provided some hints and guidance to increase the photometric accuracy of the instrument. These improvements should equip any future telescope operating in Antarctica.

  20. Tidal Energy Resource Assessment for McMurdo Station, Antarctica

    Science.gov (United States)

    2016-12-01

    unclear” (U.S. Antarctic Program Blue Ribbon Panel 2012). These studies have predominantly considered solar , wind, geother- mal, and waste wood and paper...tides are called spring tides (Figure 3). When the moon is at a right angle , perpen- dicular to the earth–sun connecting line, the lunar and solar ...capabilities at McMurdo Station, Antarctica, to reduce costs and emissions. Previous assessments considered wind, solar , and geothermal energy

  1. Direct gravimetric determination of aerosol mass concentration in central antarctica.

    Science.gov (United States)

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

    2011-01-01

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

  2. Ice crystal precipitation at Dome C site (East Antarctica)

    Science.gov (United States)

    Santachiara, G.; Belosi, F.; Prodi, F.

    2016-01-01

    For the first time, falling ice crystals were collected on glass slides covered with a thin layer of 2% formvar in chloroform at the Dome Concordia site (Dome C), Antarctica. Samplings were performed in the framework of the 27th Italian Antarctica expedition of the Italian National Program for Research in Antarctica in the period 21 February-6 August 2012. Events of clear-sky precipitations and precipitations from clouds were considered and the replicas obtained were examined under Scanning Electron Microscope (SEM). Several shapes of ice crystals were identified, including "diamond dust" (plates, pyramids, hollow and solid columns), and crystal aggregates varying in complexity. Single events often contained both small (10 μm to 50 μm) and large (hundreds of microns) crystals, suggesting that crystals can form simultaneously near the ground (height of a few hundred metres) and at higher layers (height of thousands of metres). Images of sampled crystal replicas showed that single bullets are not produced separately, but by the disintegration of combinations of bullets. Rimed ice crystals were absent in the Dome C samples, i.e. the only mode of crystal growth was water vapour diffusion. On considering the aerosol in the sampled crystals, we reached the conclusion that inertial impaction, interception and Brownian motion were insufficient to explain the scavenged aerosol. We therefore presume that phoretic forces play a role in scavenging during the crystal growth process.

  3. Antarctica's protected areas are inadequate, unrepresentative, and at risk.

    Science.gov (United States)

    Shaw, Justine D; Terauds, Aleks; Riddle, Martin J; Possingham, Hugh P; Chown, Steven L

    2014-06-01

    Antarctica is widely regarded as one of the planet's last true wildernesses, insulated from threat by its remoteness and declaration as a natural reserve dedicated to peace and science. However, rapidly growing human activity is accelerating threats to biodiversity. We determined how well the existing protected-area system represents terrestrial biodiversity and assessed the risk to protected areas from biological invasions, the region's most significant conservation threat. We found that Antarctica is one of the planet's least protected regions, with only 1.5% of its ice-free area formally designated as specially protected areas. Five of the distinct ice-free ecoregions have no specially designated areas for the protection of biodiversity. Every one of the 55 designated areas that protect Antarctica's biodiversity lies closer to sites of high human activity than expected by chance, and seven lie in high-risk areas for biological invasions. By any measure, including Aichi Target 11 under the Convention on Biological Diversity, Antarctic biodiversity is poorly protected by reserves, and those reserves are threatened.

  4. Antarctica's protected areas are inadequate, unrepresentative, and at risk.

    Directory of Open Access Journals (Sweden)

    Justine D Shaw

    2014-06-01

    Full Text Available Antarctica is widely regarded as one of the planet's last true wildernesses, insulated from threat by its remoteness and declaration as a natural reserve dedicated to peace and science. However, rapidly growing human activity is accelerating threats to biodiversity. We determined how well the existing protected-area system represents terrestrial biodiversity and assessed the risk to protected areas from biological invasions, the region's most significant conservation threat. We found that Antarctica is one of the planet's least protected regions, with only 1.5% of its ice-free area formally designated as specially protected areas. Five of the distinct ice-free ecoregions have no specially designated areas for the protection of biodiversity. Every one of the 55 designated areas that protect Antarctica's biodiversity lies closer to sites of high human activity than expected by chance, and seven lie in high-risk areas for biological invasions. By any measure, including Aichi Target 11 under the Convention on Biological Diversity, Antarctic biodiversity is poorly protected by reserves, and those reserves are threatened.

  5. Mechanically and optically controlled graphene valley filter

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Fenghua; Jin, Guojun, E-mail: gjin@nju.edu.cn [National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093 (China)

    2014-05-07

    We theoretically investigate the valley-dependent electronic transport through a graphene monolayer modulated simultaneously by a uniform uniaxial strain and linearly polarized light. Within the Floquet formalism, we calculate the transmission probabilities and conductances of the two valleys. It is found that valley polarization can appear only if the two modulations coexist. Under a proper stretching of the sample, the ratio of the light intensity and the light frequency squared is important. If this quantity is small, the electron transport is mainly contributed by the valley-symmetric central band and the conductance is valley unpolarized; but when this quantity is large, the valley-asymmetric sidebands also take part in the transport and the valley polarization of the conductance appears. Furthermore, the degree of the polarization can be tuned by the strain strength, light intensity, and light frequency. It is proposed that the detection of the valley polarization can be realized utilizing the valley beam splitting. Thus, a graphene monolayer can be used as a mechanically and optically controlled valley filter.

  6. Zhongguan Village, China's Silicon Valley

    Institute of Scientific and Technical Information of China (English)

    Liu Xinwen

    2008-01-01

    @@ In 1999,driven by the dream of using technology to change people's lives,Li Yanhong,returned to Zhongguancun(Zhongguan Village in Chinese),Beijing from Silicon Valley in the U.S.to create Baidu.com.Over the years,Baidu has become the most frequently hitted website in China as well as the largest Chinesc search engine and Chinese language website in the world.

  7. Bedmap2: improved ice bed, surface and thickness datasets for Antarctica

    Directory of Open Access Journals (Sweden)

    P. Fretwell

    2013-02-01

    Full Text Available We present Bedmap2, a new suite of gridded products describing surface elevation, ice-thickness and the seafloor and subglacial bed elevation of the Antarctic south of 60° S. We derived these products using data from a variety of sources, including many substantial surveys completed since the original Bedmap compilation (Bedmap1 in 2001. In particular, the Bedmap2 ice thickness grid is made from 25 million measurements, over two orders of magnitude more than were used in Bedmap1. In most parts of Antarctica the subglacial landscape is visible in much greater detail than was previously available and the improved data-coverage has in many areas revealed the full scale of mountain ranges, valleys, basins and troughs, only fragments of which were previously indicated in local surveys. The derived statistics for Bedmap2 show that the volume of ice contained in the Antarctic ice sheet (27 million km3 and its potential contribution to sea-level rise (58 m are similar to those of Bedmap1, but the mean thickness of the ice sheet is 4.6% greater, the mean depth of the bed beneath the grounded ice sheet is 72 m lower and the area of ice sheet grounded on bed below sea level is increased by 10%. The Bedmap2 compilation highlights several areas beneath the ice sheet where the bed elevation is substantially lower than the deepest bed indicated by Bedmap1. These products, along with grids of data coverage and uncertainty, provide new opportunities for detailed modelling of the past and future evolution of the Antarctic ice sheets.

  8. Bedmap2: improved ice bed, surface and thickness datasets for Antarctica

    Directory of Open Access Journals (Sweden)

    P. Fretwell

    2012-10-01

    Full Text Available We present Bedmap2, a new suite of gridded products describing surface elevation, ice-thickness and the seafloor and subglacial bed elevation of the Antarctic south of 60° S. We derived these products using data from a variety of sources, including many substantial surveys completed since the original Bedmap compilation (Bedmap1 in 2001. In particular, the Bedmap2 ice thickness grid is made from 25 million measurements, over two orders of magnitude more than were used in Bedmap1. In most parts of Antarctica the subglacial landscape is visible in much greater detail than was previously available and the improved coverage of data has in many areas revealed the full scale of mountain ranges, valleys, basins and troughs, only fragments of which were previously indicated in local surveys. The derived statistics for Bedmap2 show that the volume of ice contained in the Antarctic ice sheet (27 million km3 and its potential contribution to sea-level rise (58 m are similar to those of Bedmap1, but the mean thickness of the ice sheet is 4.6 % greater, the mean depth of the bed beneath the grounded ice sheet is 72 m lower and the area of ice sheet grounded on bed below sea level is increased by 10 %. The Bedmap2 compilation highlights several areas beneath the ice sheet where the bed elevation is substantially lower than the deepest bed indicated by Bedmap1. These products, along with grids of data coverage and uncertainty, provide new opportunities for detailed modelling of the past and future evolution of the Antarctic ice sheets.

  9. Preliminary microphysical characterization of precipitation at ground over Antarctica coast

    Science.gov (United States)

    Roberto, Nicoletta; Adirosi, Elisa; Montopoli, Mario; Baldini, Luca; Dietrich, Stefano; Porcù, Federico

    2017-04-01

    The primary mass input of the Antarctic ice sheet is snow precipitation which is one of the most direct climatic indicators. Climatic model simulations of precipitations over Antarctica is an important task to assess the variation of ice sheet over long temporal scale. The main source of precipitation information in Antarctica regions derive from satellite observations. However, satellite measurements and products need to be calibrated and validated with observations from ground sensors. In spite of their key role, precipitation measurements at ground are scarce and not appropriate to provide the specific characteristic of precipitation particles that influence the scattering and absorption properties of ice particles. Recently, different stations in Antarctica (Princess Elizabeth, McMurdo, Mario Zucchelli) are equipping observatories for cloud and precipitation observations. The setup of the observatory at the Italian Station, Mario Zucchelli (MZ) plans to integrate the current instrumentation for weather measurements with other instruments specific for precipitation observations, in particular, a 24-GHz vertical pointing radar and a laser disdrometer Parsivel. The synergetic use of the set of instruments allows for characterizing precipitation and studying properties of Antarctic precipitation such as dimension, shapes, fall behavior, density of particles, particles size distribution, particles terminal velocity, reflectivity factor and including some information on their vertical extent. Last November, the OTT Parsivel disdrometer was installed on the roof of a logistic container (at 6 m of height) of the MZ station (Latitude 74° 41' 42" S; Longitude 164° 07' 23E") in the Terranova Bay. The disdrometer measures size and fall velocity of particles, passing through a laser matrix from which the Particle Size Distribution (PSD) is obtained. In addition, some products such as reflectivity factor, snow rate and snow accumulation can be inferred by properly

  10. Utility of multi temporal satellite images for crop water requirements estimation and irrigation management in the Jordan Valley

    Science.gov (United States)

    Identifying the spatial and temporal distribution of crop water requirements is a key for successful management of water resources in the dry areas. Climatic data were obtained from three automated weather stations to estimate reference evapotranspiration (ETO) in the Jordan Valley according to the...

  11. Stripping with dry ice

    Science.gov (United States)

    Malavallon, Olivier

    1995-04-01

    Mechanical-type stripping using dry ice (solid CO2) consists in blasting particles of dry ice onto the painted surface. This surface can be used alone or in duplex according to type of substrate to be treated. According to operating conditions, three physical mechanisms may be involved when blasting dry ice particles onto a paint system: thermal shock, differential thermal contraction, and mechanical shock. The blast nozzle, nozzle travel speed, blast angle, stripping distance, and compressed air pressure and media flow rate influence the stripping quality and the uniformity and efficiency obtained.

  12. Blowing snow at D17, Adélie Land, Antarctica: atmospheric moisture issues

    Directory of Open Access Journals (Sweden)

    H. Barral

    2014-06-01

    Full Text Available Three years of blowing snow and meteorological observations have been collected along a 7 m mast at site D17 in coastal Adélie Land, Antarctica. This is a region particularly exposed to katabatic winds. The atmospheric surface layer is often close to saturation because of the sublimation of the airborne snow particles. A systematic dry bias results in atmospheric models that ignore blowing snow and its moistening effects, and in meteorological analyses that use such model. The Crocus snow-pack model, including a parameterization for the erosion of surface snow by wind, reproduces the observed march of snow accumulation and ablation if the observed meteorology is used as input. Because of subsaturation, a 2.5 fold increase in surface sublimation is obtained if analyzed surface air meteorology is used. The sublimation obtained in the Crocus model poorly agrees with the moisture fluxes evaluated using the profile method along the mast. Moisture gradients are very weak, particularly when blowing snow saturates the air, to a point where measurement accuracy is an issue. Using the profile method, the measurement uncertainties are strongly amplified in case of strong wind. In such conditions, a single level bulk parameterization with surface energy balance closure as in the Crocus model is preferred. At D17, more than half of the total snow fall is removed by erosion and sublimation, both at the surface and, mainly, of airborne snow particles.

  13. Spin-Valley Beam Splitter in Graphene

    CERN Document Server

    Song, Yu; Shi, Zhi-Gui; Li, Shun; Zhang, Jian

    2016-01-01

    The fourfold spin-valley degenerate degrees of freedom in bulk graphene can support rich physics and novel applications associated with multicomponent quantum Hall effects and linear conductance filtering. In this work, we study how to break the spin-valley degeneracy of electron beams spatially. We propose a spin-valley beam splitter in a gated ferromagnetic/pristine/strained graphene structure. We demonstrate that, in a full resonant tunneling regime for all spin-valley beam components, the formation of quasi-standing waves can lead four giant lateral Goos-H\\"{a}nchen shifts as large as the transverse beam width, while the interplay of the two modulated regions can lead difference of resonant angles or energies for the four spin-valley flavors, manifesting an effective spin-valley beam splitting effect. The beam splitting effect is found to be controllable by the gating and strain.

  14. California's restless giant: the Long Valley Caldera

    Science.gov (United States)

    Hill, David P.; Bailey, Roy A.; Hendley, James W.; Stauffer, Peter H.; Marcaida, Mae

    2014-01-01

    Scientists have monitored geologic unrest in the Long Valley, California, area since 1980. In that year, following a swarm of strong earthquakes, they discovered that the central part of the Long Valley Caldera had begun actively rising. Unrest in the area persists today. The U.S. Geological Survey (USGS) continues to provide the public and civil authorities with current information on the volcanic hazard at Long Valley and is prepared to give timely warnings of any impending eruption.

  15. [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...

  16. What Is Dry Eye?

    Medline Plus

    Full Text Available ... information about eye health and preserving your vision. Privacy Policy Related New Dry Eye Treatment is a ... the Academy Financial Relationships with Industry Medical Disclaimer Privacy Policy Terms of Service For Advertisers For Media ...

  17. Cold Vacuum Drying Facility

    Data.gov (United States)

    Federal Laboratory Consortium — Located near the K-Basins (see K-Basins link) in Hanford's 100 Area is a facility called the Cold Vacuum Drying Facility (CVDF).Between 2000 and 2004, workers at the...

  18. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Pediatric Ophthalmology Education Center Oculofacial Plastic Surgery Center Laser Surgery Education Center Redmond Ethics Center Global Ophthalmology Guide Eye ... What Is Dry Eye? Leer en Español: ¿Qué ...

  19. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Dry Eye Symptoms Related Ask an Ophthalmologist Answers Can a six-month dissolvable punctal plug be removed ... insert a permanent punctal plug? Sep 12, 2017 Can you explain why I have halos and blurry ...

  20. What Is Dry Eye?

    Medline Plus

    Full Text Available ... Pediatric Ophthalmology Education Center Oculofacial Plastic Surgery Center Laser Surgery Education Center Redmond Ethics Center Global Ophthalmology Guide ... What Is Dry Eye? Written By: Kierstan Boyd ...

  1. What Is Dry Eye?

    Medline Plus

    Full Text Available ... about eye health and preserving your vision. Privacy Policy Related New Dry Eye Treatment is a Tear- ... Academy Financial Relationships with Industry Medical Disclaimer Privacy Policy Terms of Service For Advertisers For Media Ophthalmology ...

  2. High-level extracellular production and characterization of Candida antarctica lipase B in Pichia pastoris.

    Science.gov (United States)

    Eom, Gyeong Tae; Lee, Seung Hwan; Song, Bong Keun; Chung, Keun-Wo; Kim, Young-Wun; Song, Jae Kwang

    2013-08-01

    The gene encoding lipase B from Candida antarctica (CalB) was expressed in Pichia pastoris after it was synthesized by the recursive PCR and cloned into the Pichia expression plasmid, pPICZαA. The CalB was successfully secreted in the recombinant P. pastoris strain X-33 with an apparent molecular weight of 34 kDa. For 140 h flask culture, the dry cell weight and the extracellular lipase activity reached at 5.4 g/l and 57.9 U/l toward p-nitrophenyl palmitate, respectively. When we performed the fed-batch fermentation using a methanol feeding strategy for 110 h, the dry cell weight and the extracellular lipase activity were increased to 135.7 g/l and 11,900 U/l; the CalB protein concentration was 1.18 g/l of culture supernatant. The characteristics of CalB recovered from the P. pastoris culture were compared with the commercial form of CalB produced in Aspergillus oryzae. The kinetic constants and specific activity, the effects of activity and stability on temperature and pH, the glycosylation extent, the degree of immobilization on macroporous resin and the yield of esterification reaction between oleic acid and n-butanol were almost identical to each other. Therefore, we successfully proved that the Pichia-based expression system for CalB in this study was industrially promising compared with one of the most efficient production systems.

  3. Intrinsic valley Hall effect in graphene

    Science.gov (United States)

    Yang, Mou; Zhang, Wen-Lian; Liu, Hai; Bai, Yan-Kui

    2017-04-01

    If electrons are incident from an armchair graphene ribbon into the bulk graphene region, the electronic diffraction occurs. Because of the different triangular wrapping of the energy dispersion between valleys K and K ‧ , the electrons of valley K tend to be diffracted to one side and those of valley K ‧ to the other side. When the current is injected from the armchair ribbon of a four-terminal graphene device, the major portion of the incident current of valley K flows through one side arm and the minor portion through the other side arm. The ratio between them is derived to be 1 + 4 E / 3 in the low energy limit, where E is the energy in units of hopping parameter. The major arm for valley K is the minor arm for valley K ‧ . This results in the rise of the valley Hall effect, which is an intrinsic property of graphene stemming from the different electronic structure of the two valleys. The valley Hall conductance is calculated to be (2 E / 3)G0 with G0 being the conductance supported by the injection ribbon.

  4. Trion valley coherence in monolayer semiconductors

    Science.gov (United States)

    Hao, Kai; Xu, Lixiang; Wu, Fengcheng; Nagler, Philipp; Tran, Kha; Ma, Xin; Schüller, Christian; Korn, Tobias; MacDonald, Allan H.; Moody, Galan; Li, Xiaoqin

    2017-06-01

    The emerging field of valleytronics aims to exploit the valley pseudospin of electrons residing near Bloch band extrema as an information carrier. Recent experiments demonstrating optical generation and manipulation of exciton valley coherence (the superposition of electron-hole pairs at opposite valleys) in monolayer transition metal dichalcogenides (TMDs) provide a critical step towards control of this quantum degree of freedom. The charged exciton (trion) in TMDs is an intriguing alternative to the neutral exciton for control of valley pseudospin because of its long spontaneous recombination lifetime, its robust valley polarization, and its coupling to residual electronic spin. Trion valley coherence has however been unexplored due to experimental challenges in accessing it spectroscopically. In this work, we employ ultrafast 2D coherent spectroscopy to resonantly generate and detect trion valley coherence in monolayer MoSe2 demonstrating that it persists for a few-hundred femtoseconds. We conclude that the underlying mechanisms limiting trion valley coherence are fundamentally different from those applicable to exciton valley coherence.

  5. Electro-dry-adhesion.

    Science.gov (United States)

    Krahn, Jeffrey; Menon, Carlo

    2012-03-27

    This work presents novel conductive bioinspired dry adhesives with mushroom caps that enable the use of a synergistic combination of electrostatic and van der Waals forces (electro-dry-adhesion). An increase in shear adhesion bond strength of up to 2046% on a wide range of materials is measured when a maximum electrical field of 36.4 V μm(-1) is applied. A suction effect, due to the shape of the dry adhesive fibers, on overall adhesion was not noted for electro-dry-adhesives when testing was performed at both atmospheric and reduced pressure. Utilization of electrostatics to apply a preloading force to dry adhesive fiber arrays allows increased adhesion even after electrostatic force generation has been halted by ensuring the close contact necessary for van der Waals forces to be effective. A comparison is made between self-preloading of the electro-dry-adhesives and the direct application of a normal preloading pressure resulting in nearly the same shear bond strength with an applied voltage of 3.33 kV on the same sample.

  6. Influence of persistent wind scour on the surface mass balance of Antarctica

    NARCIS (Netherlands)

    Das, I.; Bell, R.E.; Lenaerts, J.T.M.; Broeke, M.R. van den

    2013-01-01

    Accurate quantification of surface snow accumulation over Antarctica is a key constraint for estimates of the Antarctic mass balance, as well as climatic interpretations of ice-core records1,2. Over Antarctica, near-surface winds accelerate down relatively steep surface slopes, eroding and sublimati

  7. Relative sea-level rise around East Antarctica during Oligocene glaciation

    NARCIS (Netherlands)

    Stocchi, P.; Escutia, C.; Houben, A.J.P.; Vermeersen, B.L.A.; Bijl, P.K.; Brinkhuis, H.; Deconto, R.M.; Galeotti, S.; Passchier, S.; Pollard, D.

    2013-01-01

    During the middle and late Eocene (∼ 48-34 Myr ago), the Earth's climate cooled and an ice sheet built up on Antarctica. The stepwise expansion of ice on Antarctica induced crustal deformation and gravitational perturbations around the continent. Close to the ice sheet, sea level rose despite an ove

  8. Relative sea-level rise around East Antarctica during Oligocene glaciation

    NARCIS (Netherlands)

    Stocchi, P.; Escutia, C.; Houben, A.J.P.; Vermeersen, B.L.A.; Bijl, P.K.; Brinkhuis, H.; DeConto , R.M.; Galeotti, S.; Passchier, S.; Pollard, D.; IODP Expedition 318 Scientists; Houben, A.J.P.

    2013-01-01

    During the middle and late Eocene (similar to 48-34 Myr ago), the Earth's climate cooled(1,2) and an ice sheet built up on Antarctica. The stepwise expansion of ice on Antarctica(3,4) induced crustal deformation and gravitational perturbations around the continent. Close to the ice sheet, sea level

  9. Relative sea-level rise around East Antarctica during Oligocene glaciation

    NARCIS (Netherlands)

    Stocchi, P.; Escutia, C.; Houben, A.J.P.; Vermeersen, B.L.A.; Bijl, P.K.; Brinkhuis, H.; Deconto, R.M.; Galeotti, S.; Passchier, S.; Pollard, D.

    2013-01-01

    During the middle and late Eocene (∼ 48-34 Myr ago), the Earth's climate cooled and an ice sheet built up on Antarctica. The stepwise expansion of ice on Antarctica induced crustal deformation and gravitational perturbations around the continent. Close to the ice sheet, sea level rose despite an ove

  10. Relative sea-level rise around East Antarctica during Oligocene glaciation

    NARCIS (Netherlands)

    Stocchi, P.; Escutia, C.; Houben, A.J.P.; Vermeersen, B.L.A.; Bijl, P.K.; Brinkhuis, H.; DeConto , R.M.; Galeotti, S.; Passchier, S.; Pollard, D.; IODP Expedition 318 Scientists; Houben, A.J.P.

    2013-01-01

    During the middle and late Eocene (similar to 48-34 Myr ago), the Earth's climate cooled(1,2) and an ice sheet built up on Antarctica. The stepwise expansion of ice on Antarctica(3,4) induced crustal deformation and gravitational perturbations around the continent. Close to the ice sheet, sea level

  11. Antibacterial, antifungal and antiprotozoal activities of fungal communities present in different substrates from Antarctica

    Science.gov (United States)

    Antarctica is a pristine and extreme environment that represents a unique opportunity for taxonomic, ecological and biotechnological studies of the microorganisms. In the present work, the fungal communities of rhizosphere soil of Deschampsia antarctica, soil, ornithogenic soil, marine and lake sedi...

  12. Antarctica: The Continuing Experiment. Foreign Policy Association Headline Series, No. 273.

    Science.gov (United States)

    Quigg, Philip W.

    One of a series of booklets on world issues examines the sharpened differences between those nations that have declared sovereignty over parts of Antarctica and those that have not; between those nations that have arbitrarily assumed responsibility for the administration of Antarctica and the smaller, more numerous nations that believe their…

  13. Uniformitarianism: A Comparative Study of the Global Transitional Climatic Area Influences on the Bampur Valley

    Directory of Open Access Journals (Sweden)

    Mohammad Salighe

    2012-12-01

    Full Text Available The aim of this paper is to examine the interactions between people and the natural environment against a background of climatic change. The focus of attention is on the Bampur Valley, which is located in the global transitional climatic area. During the fourth and third millennium BCE, an important urban society, which was in close economic contacts with the urban societies of the Sistan Basin, Jiroft, Soghan Valley, the Indus Valley and Mesopotamia, emerged in this Bampur Valley along the river bed of the Bampur River. This Valley, which is located along the main natural overland trade routes, not only developed as intermediary for long-distance trade between east and west but also functioned as an important industrial and economical pole in southeast Iran. It is argued that the global transitional climate area, which is generally located between tropical and subtropical areas, has constantly been faced with periodical changes including dry and humid during worm period. Based on the archaeological and environmental evidence, with reference to uniformitarianism theory and with using GIS, it will be attempted to evaluate movement, collapse and interaction between settlements and natural environment in the Bampur Valley. The disciplines of archaeology and geography have much in common, being concern respectively with the spatial and temporal dimensions of the human condition. Archaeology deals with those aspects of the human past which are mainly elucidated using material remains rather than written sources. The prime concern of geography is to understand the processes that operate within the natural environment (physical geography and to evaluate the ways in which people interact both with their environment and with each other (human geography. Evidence discovered from the archaeological and geographical surveys carried out in the area between 2002 and 2005 by authors testify to environmental changes, which caused instability and collapse of the

  14. Iron and nutrient content of wind-erodible sediment in the ephemeral river valleys of Namibia

    Science.gov (United States)

    Dansie, A. P.; Wiggs, G. F. S.; Thomas, D. S. G.

    2017-08-01

    Research concerning the global distribution of aeolian dust sources has principally focussed on salt/clay pan and desiccated lacustrine emission areas. In southern Africa such sources are identified as Etosha Pan in northern Namibia and Makgadikgadi Pans in northern Botswana. Dust emitting from ephemeral river valleys, however, has been largely overlooked. Rivers are known nutrient transport pathways and the flooding regimes of ephemeral river valleys frequently replenish stores of fine sediment which, on drying, can become susceptible to aeolian erosion. Such airborne sediment may be nutrient rich and thus be significant for the fertilisation of marine waters once deposited. This study investigates the dust source sediments from three ephemeral river valleys in Namibia in terms of their particle size distribution and their concentrations of bioavailable N, P and Fe. We compare the nutrient content of these sediments from the ephemeral river valleys to those collected from Etosha and Makgadikgadi Pans and consider their relative ocean fertilising potential. Our results show that the ephemeral river valleys contain fine grained sediment similar in physical character to Etosha and Makgadikgadi Pans yet they have up to 43 times greater concentrations of bioavailable iron and enriched N and P macronutrients that are each important for ocean fertilisation. The known dust-emitting river valleys of Namibia may therefore be contributing a greater fertilisation role in the adjacent marine system than previously considered, and not-yet investigated. Given this finding a re-assessment of the potential role of ephemeral river valleys in providing nutrient-rich sediment into the aeolian and marine systems in other dryland areas is necessary.

  15. Observing Seasonal and Diurnal Hydrometeorological Variability Within a Tropical Alpine Valley: Implications for Evapotranspiration

    Science.gov (United States)

    Hellstrom, R. A.; Mark, B. G.

    2007-12-01

    Conditions of glacier recession in the seasonally dry tropical Peruvian Andes motivate research to better constrain the hydrological balance in alpine valleys. There is an outstanding need to better understand the impact of the pronounced tropical hygric seasonality on energy and water budgets within pro-glacial valleys that channel glacier runoff to stream flow. This paper presents a novel embedded network installed in the glacierized Llanganuco valley of the Cordillera Blanca (9°S) comprising eight low-cost, discrete temperature and humidity microloggers ranging from 3470 to 4740 masl and an automatic weather station at 3850 masl. Data are aggregated into distinct dry and wet periods sampled from two full annual cycles (2004-2006) to explore patterns of diurnal and seasonal variability. The magnitude of diurnal solar radiation varies little within the valley between the dry and wet periods, while wet season near-surface air temperatures are cooler. Seasonally characteristic diurnal fluctuations in lapse rate partially regulate convection and humidity. Steep lapse rates during the wet season afternoon promote up-slope convection of warm, moist air and nocturnal rainfall events. Standardized grass reference evapotranspiration (ET0) was estimated using the FAO-56 algorithm of the United Nations Food and Agriculture Organization and compared with estimates of actual ET from the process-based BROOK90 model that incorporates more realistic vegetation parameters. Comparisons of composite diurnal cycles of ET for the wet and dry periods suggest about twice the daily ET0 during the dry period, attributed primarily to the 500% higher vapor pressure deficit and 20% higher daily total solar irradiance. Conversely, the near absence of rainfall during the dry season diminishes actual ET below that of the wet season by two orders of magnitude. Nearly cloud-free daylight conditions are critical for ET during the wet season. We found significant variability of ET with elevation

  16. Precision Mapping of Valley Networks in Margaritifer Sinus, Mars

    Science.gov (United States)

    Stepinski, T. F.; Luo, W.; Qi, Y.

    2007-03-01

    Valley networks in Margaritifer Sinus quadrangle are mapped using a computer algorithm. The new map reveals wider existence of valleys than has been inferred from older maps. This suggests runoff as the primary mechanism for origin of the valleys.

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

    Science.gov (United States)

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

    2013-01-01

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

  18. Work through the valley: plan.

    Science.gov (United States)

    Jones, Loretta; Meade, Barbara; Koegel, Paul; Lucas-Wright, Aziza; Young-Brinn, Angela; Terry, Chrystene; Norris, Keith

    2009-01-01

    This first of three chapters on the Valley stage, or main work of a Community-Partnered Participatory Research (CPPR) initiative, concerns the planning phase of the work cycle. The main goal of this phase is to develop an action plan, which clarifies the goals, methods, responsible individuals, and timeline for doing the work. Further, this chapter reviews approaches, such as creativity and use of humor, that help level the playing field and assure community co-leadership with academic partners in developing effective action plans.

  19. U.S. Geological Survey Scientific Activities in the Exploration of Antarctica: Introduction to Antarctica (Including USGS Field Personnel: 1946-59)

    Science.gov (United States)

    Tony K. Meunier Edited by Williams, Richard S.; Ferrigno, Jane G.

    2007-01-01

    INTRODUCTION Antarctica is the planet's fifth largest continent [13.2 million km2 (5.1 million mi2)]; it contains the Earth's largest (of two) remaining ice sheets; it is considered to be one of the most important scientific laboratories on Earth. This report is the introduction to a series that covers 60 years of U.S. Geological Survey (USGS) scientific activity in Antarctica. It will concentrate primarily on three major topics:

  20. Special offer-7 days fly and drive Antarctica: The role of wilderness protection in deciding whether (semi) permanent tourist facilities in Antarctica should be prohibited

    Science.gov (United States)

    Kees Bastmeijer

    2007-01-01

    Antarctica is often described as one of the world’s last wildernesses. Since 1990, tourism to this wilderness is developing rapidly. In a period of 15 years, the number of tourists that make landings in Antarctica has increased from 2,500 (1990/91) to more than 23,000 (2004/05). The diversity of tourist activities is also increasing. The 1991 Protocol on Environmental...

  1. Reconstruction of the East Africa and Antarctica continental margins

    Science.gov (United States)

    Nguyen, Luan C.; Hall, Stuart A.; Bird, Dale E.; Ball, Philip J.

    2016-06-01

    The Early Jurassic separation of Antarctica from Africa plays an important role in our understanding of the dispersal of Gondwana and Pangea. Previous reconstruction models contain overlaps and gaps in the restored margins that reflect difficulties in accurately delineating the continent-ocean-boundary (COB) and determining the amount and distribution of extended continental crust. This study focuses on the evolution of the African margin adjacent to the Mozambique Basin and the conjugate Antarctic margin near the Riiser-Larsen Sea. Satellite-derived gravity data have been used to trace the orientations and landward limits of fracture zones. A 3-D gravity inversion has produced a crustal thickness model that reliably quantifies the extent and amount of stretched crust. Crustal thicknesses together with fracture zone terminations reveal COBs that are significantly closer to the African and Antarctic coasts than previously recognized. Correlation of fracture zone azimuths and identified COBs suggests Antarctica began drifting away from Africa at approximately 171 Ma in a roughly SSE direction. An areal-balancing method has been used to restore the crust to a uniform prerift thickness so as to perform a nonrigid reconstruction for both nonvolcanic and volcanic margins. Both margins reveal a trend of increasing extension from east to west. Our results suggest Africa underwent extension of 60-120 km, while Antarctic crust was stretched by 105-180 km. Various models tested to determine the direction of extension during rifting suggest that Antarctica moved away from Africa in a WNW-ESE direction during the period between 184 and 171 Ma prior to the onset of seafloor spreading.

  2. Seasonal features of black carbon measured at Syowa Station, Antarctica

    Science.gov (United States)

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

    2015-12-01

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

  3. Hypolithic Biocrust in the Larsemann Hills of East Antarctica: Spatial Patterns, Organic Matter Stabilization, Comparison with Endolithic Systems

    Science.gov (United States)

    Mergelov, Nikita; Dolgikh, Andrey; Shorkunov, Ilya; Zazovskaya, Elya; Shishkov, Vasily; Pochikalov, Alexander

    2017-04-01

    The survey conducted in the Larsemann Hills oasis of East Antarctica (69°24'S, 76°14'E) revealed that hypolithic and endolithic bio-abiotic systems occupy from 20 to 60% of the wet valleys floors and slopes area. As in many other parts of Antarctica a significant portion of organic matter in Larsemann Hills is produced in cryptic niches inside the fissure network of hard rocks or under the stone pavements on loose sediments. The dominant autotrophic components of such ecosystems are cyanobacteria and green algae, mainly in the form of biofilms. However moss dominated communities could form distinct patterns within hypolithic biocrust. The spatial distribution of various types of hypolithic biocrusts, its thickness, moisture content, carbon and nitrogen content/stocks, as well as C/N ratios were studied at a detailed scale at several key sites along the grid of 10x10 m with a step of 1 m (121 sampling points each). The data received are evident that microbial and cryptogamic photoautotrophs activity in hidden habitats under the stone pavements could lead to the substantial organic matter accumulation in extreme environment of East Antarctica - up to 5% of C and 0.4% of N. However the radiocarbon data indicate that in many cases the values of fraction modern (F14C) exceed "1" which means that organic matter in hypolithic biocrust is not preserved in a long-term period. This contrasts with 14C "ages" of endolithic systems on surrounding slopes of the valley exceeding 500 and sometimes 1000 yr BP. We found that once hypolithic organogenous material is buried under sand and gravel 2-5 cm deeper than common hypolithic biocrust it could preserve for a dramatically longer periods and have the 14C "age" up to 1100 yr BP. As evidenced by optical and scanning electron microscopy with EDX this old organogenous material of hypolithic origin still retains clear filamentous structure of cyanobacteria biofilm as well as remnants of EPS stabilized mainly by amorphous Si and Al

  4. 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.

  5. Drying of Malaysian Capsicum annuum L. (Red Chili) Dried by Open and Solar Drying

    OpenAIRE

    Ahmad Fudholi; Mohd Yusof Othman; Mohd Hafidz Ruslan; Kamaruzzaman Sopian

    2013-01-01

    This study evaluated the performance of solar drying in the Malaysian red chili (Capsicum annuum L.). Red chilies were dried down from approximately 80% (wb) to 10% (wb) moisture content within 33 h. The drying process was conducted during the day, and it was compared with 65 h of open sun drying. Solar drying yielded a 49% saving in drying time compared with open sun drying. At the average solar radiation of 420 W/m2 and air flow rate of 0.07 kg/s, the collector, drying system, and pickup de...

  6. Psychrotrophic ~Iydrolytic Bacteria from Antarctica &,Other I. Low Temperature Habitats

    Directory of Open Access Journals (Sweden)

    K.V. Ramana

    2000-04-01

    Full Text Available Samples of water, soil,llake sediments and blue-green algal mats from Antarctica were'processed for enumeration, isolation and screening of psychrotrophic hydrolytic bacteria. Amylolytic bacteria were preponderant (75 per cent in the blue-green algal htat samples. Protease, lipase, an1ylase and urerse producing/bacteria were also isolated from the samples. ,Biochemical characteristics indicated that the isolates ;mainly comprised Pseudomonas and Bacillus species. Proteases and lipases of antarctic bacterial strains preferably hydrolysed denatured protein substrate and water soluble monomeric synthetic lipid substrates, respectively.

  7. Meteorites from Grove Mountains, Antarctica:An overview

    Institute of Scientific and Technical Information of China (English)

    王道德; 林杨挺

    2003-01-01

    Thirty-two meteorites were collected in Grove Mountains area, Antarctica,by the 15th and 16th Chinese Antarctic Research Expeditions (CHINARE). Petrography and mineral chemistry of these meteorites are reviewed, among which there are one Martian lherzolite, one eucrite, one ungrouped iron meteorite, and six unequilibrated and twenty-three equilibrated ordinary chondrites. An equilibrated ordinary chondrite GRV 98004 (H5) has an unusually low cosmic-ray exposure age. Meteorite concentrating processes in Grove Mountains area are discussed. In addition, future studies on Grove Mountains (GRV) meteorites are proposed.

  8. An assessment of forward and inverse GIA solutions for Antarctica

    Science.gov (United States)

    Bamber, Jonathan L.; Martin, Alba; King, Matt; Zammit-Mangion, Andrew

    2016-04-01

    GIA has, until recently, been estimated using forward models that attempt to determine how the solid Earth responds to changes in ice-ocean loading through time. These models require knowledge of spatially-varying Earth rheology, including mantle viscosity, and ice load history, both of which have large uncertainties for Antarctica. Recent advances in GIA models include consideration of three-dimensional variations in Earth rheology and power-law rheologies. Such GIA models predict remarkably different patterns of uplift over Antarctica when compared to those using one-dimensional Earth models, such as a shift in the uplift maximum from the Ross to the Wedell Sea (van der Wal et al., 2015). However, large uncertainties still remain in the ice loading history models (A. et al 2014 and van der Wal et al., 2015) and substantial regional differences are found between Antarctic reconstructions. An alternative approach is to use observations of crustal motion from GPS, combined with mass trends from GRACE to invert for GIA. However, this is an undetermined problem which requires assumptions on the density profile of the ice column for which numerical models have been commonly used (Gunter el al., 2014). Here we present a novel solution to the inverse problem using state-of-the-art methods in statistical modelling of spatio-temporal processes. Specifically, we combine observational data, including satellite radar and laser altimetry, GRACE, GPS and InSAR, with prior information on the spatial and temporal smoothness of the underlying process to solve, simultaneously, for ice mass trends and GIA. This is achieved via a spatio-temporal Bayesian hierarchical model and the resulting solution is only dependent on length and smoothness properties obtained from numerical models, but is otherwise entirely data-driven. We compare the most recent forward and inverse GIA solutions for Antarctica with a set of 68 observed vertical velocities over the period 2009 -- 2014 from the GPS

  9. Advanced systems data for mapping Emperor Penguin habitats in Antarctica

    Science.gov (United States)

    Sanchez, Richard D.; Kooyman, Gerald L.

    2004-01-01

    Commercial orbital sensor systems combined with other resource data from the U.S. Geological Survey National Civil Applications Program (NCAP) may offer an effective way of mapping Emperor penguin habitats and their response to regional climate change in Antarctica. This project examined these resources to determine their applicability for mapping Emperor penguin habitats to support the National Science Foundation. This work is especially significant to investigate satellite-based imaging as an alternative to intrusive in-the-field enumeration of Emperor penguins and the potential of applying these procedures to support The National Map (TNP).

  10. Wind power in Antarctica - a feasibility study for Wasa

    Energy Technology Data Exchange (ETDEWEB)

    Lindquist, Anna [Uppsala Univ. (Sweden). Div. for Electricity and Lightning Research

    2004-07-01

    The Swedish Polar Research Secretariat maintains two research stations in Antarctica, Wasa and Svea. They are both small, summer-only stations that are manned a few months at a time during the regular expeditions to the continent. Recently, Swedish scientists asked for the possibility to make around-the-year measurements with automatic equipment at the two stations. Since Wasa and Svea are only manned occasionally, this request implies the need for a new power supply system. The demands imposed on this new, separate system are hard. The continent is the coldest, windiest and driest on earth and the power supply system must be designed to withstand the harsh conditions. Since there is no personnel present during the Antarctic winter, the system also has to be autonomous and very reliable. The environment in Antarctica is sensitive and protected by strict regulations that all members of the Antarctic Treaty are obliged to follow. More and more nations are revising their power supply systems in order to find substitutions for the conventional diesel generators, and wind power has been installed at several stations and has worked well in many cases. This master thesis project is a feasibility study aimed at investigating whether wind power is a convenient solution in a separate power supply system at Wasa. During the project, wind data from weather stations in Antarctica have been used to map the wind resources at the two research stations. Although more accurate wind measurements would be needed for a complete evaluation of the wind resources, it can be seen that the prerequisites for wind power are good at Wasa. The wind is very directional, the wind speeds are moderate and the temperatures not too low. A wind turbine modified for the climate in Antarctica should function well at Wasa, in combination with a battery bank with NiCd batteries. Two turbines that fulfil most of the demands imposed on them and that seem to perform well in the conditions at Wasa were found

  11. Accelerated sea-level rise from West Antarctica.

    OpenAIRE

    Thomas, R; Rignot, E.; Casassa, G; Kanagaratnam, P; Acuña, C; Akins, T; Brecher, H; E Frederick; Gogineni, P.; Krabill, W.; Manizade, S.; Ramamoorthy, H; Rivera, A.; Russell, R.; Sonntag, J

    2004-01-01

    Recent aircraft and satellite laser altimeter surveys of the Amundsen Sea sector of West Antarctica show that local glaciers are discharging about 250 cubic kilometers of ice per year to the ocean, almost 60% more than is accumulated within their catchment basins. This discharge is sufficient to raise sea level by more than 0.2 millimeters per year. Glacier thinning rates near the coast during 2002-2003 are much larger than those observed during the 1990s. Most of these glaciers flow into flo...

  12. GIS-ILA:THE GIS FOR ITALIAN LOGISTICS IN ANTARCTICA

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A geographic information system (GIS) is a hardware/software tool which is very effective in collecting,storing,searching,handling,and visualizing geographic data together with their descriptive attributes.Such a tool is very helpful to approach a wide range of situations,including many logistic problems.ENEA,as the agency having the task of implementing the Italian Antarctic Program (PNRA),has decided to use a GIS,in order to increase the efficiency in managing the huge amount of data collected in the course of Italian activity in Antarctica,which counts fifteen expeditions up to now.

  13. Detection of evolutionarily distinct avian influenza a viruses in antarctica.

    Science.gov (United States)

    Hurt, Aeron C; Vijaykrishna, Dhanasekaran; Butler, Jeffrey; Baas, Chantal; Maurer-Stroh, Sebastian; Silva-de-la-Fuente, M Carolina; Medina-Vogel, Gonzalo; Olsen, Bjorn; Kelso, Anne; Barr, Ian G; González-Acuña, Daniel

    2014-05-06

    ABSTRACT Distinct lineages of avian influenza viruses (AIVs) are harbored by spatially segregated birds, yet significant surveillance gaps exist around the globe. Virtually nothing is known from the Antarctic. Using virus culture, molecular analysis, full genome sequencing, and serology of samples from Adélie penguins in Antarctica, we confirmed infection by H11N2 subtype AIVs. Their genetic segments were distinct from all known contemporary influenza viruses, including South American AIVs, suggesting spatial separation from other lineages. Only in the matrix and polymerase acidic gene phylogenies did the Antarctic sequences form a sister relationship to South American AIVs, whereas distant phylogenetic relationships were evident in all other gene segments. Interestingly, their neuraminidase genes formed a distant relationship to all avian and human influenza lineages, and the polymerase basic 1 and polymerase acidic formed a sister relationship to the equine H3N8 influenza virus lineage that emerged during 1963 and whose avian origins were previously unknown. We also estimated that each gene segment had diverged for 49 to 80 years from its most closely related sequences, highlighting a significant gap in our AIV knowledge in the region. We also show that the receptor binding properties of the H11N2 viruses are predominantly avian and that they were unable to replicate efficiently in experimentally inoculated ferrets, suggesting their continuous evolution in avian hosts. These findings add substantially to our understanding of both the ecology and the intra- and intercontinental movement of Antarctic AIVs and highlight the potential risk of an incursion of highly pathogenic AIVs into this fragile environment. IMPORTANCE Avian influenza viruses (AIVs) are typically maintained and spread by migratory birds, resulting in the existence of distinctly different viruses around the world. However, AIVs have not previously been detected in Antarctica. In this study, we

  14. Summer weather characteristics on the Grove Mountain of East Antarctica

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The summer weather characteristics of the Grove Mountain, East Antarctica, are presented based on the data obtained by Chinese National Antarctic Expedition (CHINARE) in January 1999. The result shows that the pattern of daily variation of temperature and the prevailing wind direction in Grove is similar to that of Zhongshan Station. However, the daily range of temperature and strong wind frequency are much higher than those of Zhongshan Station. The change of wind direction is close to the weather system that impacted the Grove Mountain. The warm and wet air from northern parts often causes the precipitation. The clear weather appears when controlled by eastern winds in January.

  15. Triassic leech cocoon from Antarctica contains fossil bell animal

    DEFF Research Database (Denmark)

    Bomfleur, Benjamin; Kerp, Hans; Taylor, Thomas N.

    2012-01-01

    Our understanding of the evolution of life on Earth is limited by the imperfection of the fossil record. One reason for this imperfect record is that organisms without hard parts, such as bones, shells, and wood, have a very low potential to enter the fossil record. Occasionally, however......, exceptional fossil deposits that preserve soft-bodied organisms provide a rare glimpse of the true biodiversity during past periods of Earth history. We here present an extraordinary find of a fossil ciliate that is encased inside the wall layer of a more than 200 Ma leech cocoon from Antarctica...

  16. 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,...

  17. Rift Valley fever outbreak, southern Mauritania, 2012.

    Science.gov (United States)

    Sow, Abdourahmane; Faye, Ousmane; Ba, Yamar; Ba, Hampathé; Diallo, Diawo; Faye, Oumar; Loucoubar, Cheikh; Boushab, Mohamed; Barry, Yahya; Diallo, Mawlouth; Sall, Amadou Alpha

    2014-02-01

    After a period of heavy rainfall, an outbreak of Rift Valley fever occurred in southern Mauritania during September-November 2012. A total of 41 human cases were confirmed, including 13 deaths, and 12 Rift Valley fever virus strains were isolated. Moudjeria and Temchecket Departments were the most affected areas.

  18. Valley Fever (Coccidioidomycosis) Risk and Prevention

    Science.gov (United States)

    ... fungal spores. The following are some common-sense methods that may be helpful to avoid getting Valley fever. It’s important to know that although these steps are recommended, they haven’t been proven to prevent Valley fever. ... information about respirators. Stay inside during dust storms and ...

  19. 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,

  20. Valley Pearl’ table grape

    Science.gov (United States)

    Valley Pearl’ is an early to mid-season, white seedless table grape (Vitis vinifera L.) suitable for commercial table grape production where V. vinifera can be grown. Significant characteristics of ‘Valley Pearl’ are its high and consistent fruit production on spur pruned vines and large round berr...

  1. Exploration of Gamburtsev Subglacial Mountains, East Antarctica: Background and Plans for the Near Future

    Science.gov (United States)

    Talalay, Pavel; Sun, Youhong; Zhao, Yue; Li, Yuansheng; Cao, Pinlu; Xu, Huiwen; Zheng, Zhichuan; Wang, Rusheng; Zhang, Nan; Markov, Alexey; Yu, Dahui; Fan, Xiaopeng; Hu, Zhengyi; Yang, Cheng; Gong, Da; Hong, Jialing; Liu, Chunpeng; Han, Junjie; Yu, Chengfeng; Wang, Lili

    2014-05-01

    The Gamburtsev Subglacial Mountains (GSM), located in the central part of East Antarctica, were discovered by the Soviet team of the 3rd Complex Antarctic Expedition in 1958-1959. The GSM has highly dissected Alpine topography reaching maximum elevations of 3000 m and are completely covered by over 600 m of ice and snow. The mechanism driving uplift of the young-shaped GSM in the middle of the old East Antarctic Shield is unknown. With only limited constraints available on the topography, geology, and lithospheric structure, the origin of the GSM has been a matter of considerable speculation. The latest interpretation suggested that the GSM were formed during Permian and Cretaceous (roughly 250-100 Ma ago) due to the combination of rift-flank uplift, root buoyancy and the isostatic response. Later on, the Antarctic Ice Sheet covered the range and protected it from erosion. However, this theory cannot explain lack of erosion process during many millions years in between uplifting and beginning of glaciation. The next step of the GSM exploration focuses on the direct observation of ice sheet bed by drilling. In order to penetrate into subglacial bedrock in the GSM region the development activity already has been started in China. Drilling operations in Antarctica are complicated by extremely low temperature at the surface and within ice sheet, by ice flow, the absence of roads and infrastructures, storms, winds, snowfalls, etc. All that are the reasons that up to the present moment bedrock cores were never obtained at inland of Antarctica. It is proposed to use cable-suspended drilling technology in which an armored cable with a winch is used instead of a pipe-string to provide power to the down-hole motor system and to retrieve the down-hole unit. It is assumed to choose the drill site with the ice thickness at most of 1000 m and to pierce into the mountain slope to a depth of few meters. Proposed borehole construction includes five following steps: (1) dry core

  2. Drying of Concrete

    DEFF Research Database (Denmark)

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

    2002-01-01

    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...

  3. Drying of Concrete

    DEFF Research Database (Denmark)

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

    2002-01-01

    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...

  4. Trigger Point Dry Needling.

    Science.gov (United States)

    2017-03-01

    Increasingly, physical therapists in the United States and throughout the world are using dry needling to treat musculoskeletal pain, even though this treatment has been a controversial addition to practice. To better generalize to physical therapy practice the findings about dry needling thus far, the authors of a study published in the March 2017 issue of JOSPT identified the need for a systematic review examining the effectiveness of dry needling performed by physical therapists on people with musculoskeletal pain. Their review offers a meta-analysis of data from several included studies and assesses the evidence for risks of bias. J Orthop Sports Phys Ther 2017;47(3):150. doi:10.2519/jospt.2017.0502.

  5. Magnetically responsive dry fluids

    Science.gov (United States)

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

    2013-07-01

    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.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. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01784b

  6. Transforming the "Valley of Death" into a "Valley of Opportunity"

    Science.gov (United States)

    Jedlovec, Gary J.; Merceret, Francis J.; O'Brien, T. P.; Roeder, William P.; Huddleston, Lisa L.; Bauman, William H., III

    2014-01-01

    Transitioning technology from research to operations (23 R2O) is difficult. The problem's importance is exemplified in the literature and in every failed attempt to do so. Although the R2O gap is often called the "valley of death", a recent a Space Weather editorial called it a "Valley of Opportunity". There are significant opportunities for space weather organizations to learn from the terrestrial experience. Dedicated R2O organizations like those of the various NOAA testbeds and collaborative "proving ground" projects take common approaches to improving terrestrial weather forecasting through the early transition of research capabilities into the operational environment. Here we present experience-proven principles for the establishment and operation of similar space weather organizations, public or private. These principles were developed and currently being demonstrated by NASA at the Applied Meteorology Unit (AMU) and the Short-term Prediction Research and Transition (SPoRT) Center. The AMU was established in 1991 jointly by NASA, the U.S. Air Force (USAF) and the National Weather Service (NWS) to provide tools and techniques for improving weather support to the Space Shuttle Program (Madura et al., 2011). The primary customers were the USAF 45th Weather Squadron (45 WS) and the NWS Spaceflight Meteorology Group (SMG who provided the weather observing and forecast support for Shuttle operations). SPoRT was established in 2002 to transition NASA satellite and remote-sensing technology to the NWS. The continuing success of these organizations suggests the common principles guiding them may be valuable for similar endeavors in the space weather arena.

  7. Hereditary stomatocytosis: First case report from Valley of Kashmir

    Directory of Open Access Journals (Sweden)

    Javid Rasool

    2015-01-01

    Full Text Available Stomatocytes are erythrocytes with a central slit or mouth-shaped (stoma area of central pallor when examined on dried smears. In wet preparations, they are uniconcave rather than biconcave, giving them a bowllike appearance. In vitro, stomatocytes are produced by drugs that intercalate into the inner half of the lipid bilayer, thereby expanding the inner lipid surface area relative to that of the outer half of the bilayer. Hereditary stomatocytosis (also known as hereditary hydrocytosis, or overhydrated stomatocytosis refers to a heterogeneous group of autosomal dominant hemolytic anemias caused by altered sodium permeability of the red cell membrane. We present the first case report of hereditary stomatocytosis in a 10-year-old male from the valley of Kashmir. Only eight families with this condition have been described worldwide.

  8. Measurements of spectral snow albedo at Neumayer, Antarctica

    Directory of Open Access Journals (Sweden)

    S. Wuttke

    2006-03-01

    Full Text Available Spectral albedo in high resolution, from 290 to 1050 nm, has been measured at Neumayer, Antarctica, (70°39' S, 8°15' W during the austral summer 2003/2004. At 500 nm, the spectral albedo nearly reaches unity, with slightly lower values below and above 500 nm. Above 600 nm, the spectral albedo decreases to values between 0.45 and 0.75 at 1000 nm. For one cloudless case an albedo up to 1.01 at 500 nm could be determined. This can be explained by the larger directional component of the snow reflectivity for direct incidence, combined with a slightly mislevelled sensor and the snow surface not being perfectly horizontal. A possible explanation for an observed decline in albedo is an increase in snow grain size. The theoretically predicted increase in albedo with increasing solar zenith angle (SZA could not be observed. This is explained by the small range of SZA during albedo measurements, combined with the effect of changing snow conditions outweighing the effect of changing SZA. The measured spectral albedo serves as input for radiative transfer models, describing radiation conditions in Antarctica.

  9. Chemical composition of the sediment from Lake 20 (Antarctica

    Directory of Open Access Journals (Sweden)

    Daria ROSSI

    2000-02-01

    Full Text Available Lake 20 (19,000 m2 is located on the coast of the Ross Sea, in the North-Central part of Victoria Land, and its surface is ice-free between the end of December and early February. Within the framework of the Italian National Research Programme in Antarctica, a study was made of the chemical composition of sediments from the lake, with the intention of using this information to contribute to a better understanding of the processes involved in the long range transport of pollutants and their role in global changes. A sediment core from Lake 20 (Antarctica, 18 cm long, was collected in 1994, sliced into 2 cm sections and analysed using X Ray fluorescence spectrometry for 17 elements (Si, Al, Ca, K, Fe, Mg, Ti, S, P, Pb, Zn, Cu, Ni, Mn, Cr, Na, Cl, by CHN Elemental Analyser for C and N, by Flameless Atomic Absorption Spectrometry for As, and by Cold Vapour Atomic Absorption Spectrometry for Hg. The chemical composition of the sediments is consistent with the known geochemical characteristics of the drainage basin. While the chemical analyses reveal that sedimentation in Lake 20 has changed through time, the variations along the core are most probably related to the climatic evolution of the area, to the consequent changes in weathering processes, and possibly to an increase in the primary productivity of the lake, rather than to anthropogenic influences on the biogeochemical cycles of the elements.

  10. Surface and snowdrift sublimation at Princess Elisabeth station, East Antarctica

    Directory of Open Access Journals (Sweden)

    W. Thiery

    2012-04-01

    Full Text Available In the near-coastal regions of Antarctica, a significant fraction of the snow precipitating onto the surface is removed again through sublimation – either directly from the surface or from drifting snow particles. Meteorological observations from an Automatic Weather Station (AWS near the Belgian research station Princess Elisabeth in Dronning Maud Land, East-Antarctica, are used to study surface and snowdrift sublimation and to assess their impacts on both the surface mass balance and the surface energy balance. Comparison to three other AWSs in Dronning Maud Land shows that sublimation has a significant influence on the surface mass balance at katabatic locations by removing 10–23 % of their total precipitation, but at the same time reveals anomalously low surface and snowdrift sublimation rates at Princess Elisabeth (18 mm w.e. yr–1 compared to 42 mm w.e. yr–1 at Svea Cross and 52 mm w.e. yr–1 at Wasa/Aboa. This anomaly is attributed to local topography, which shields the station from strong katabatic influence, and therefore on the one hand allows for a strong surface inversion to persist throughout most of the year and on the other hand causes a lower probability of occurrence of intermediately strong winds. These wind speed classes turn out to contribute most to the total snowdrift sublimation mass flux, given their ability to lift a high number of particles while still allowing for considerable undersaturation.

  11. Deep Drilling with the ANDRILL Program in Antarctica

    Directory of Open Access Journals (Sweden)

    Alex Pyne

    2006-09-01

    Full Text Available ANDRILL (ANtarctic geological DRILLing is a new international, multi-disciplinary drilling program that targets geological records that lie hidden beneath the icy blanket of Antarctica. The primary objective is to investigate Antarctica’s role in global environmental change over the past sixty-fi ve million years, at various scales of age resolution, and thereby enhance our understanding of Antarctica’s potential response to future global changes. Efforts to understand the infl uence of Antarctica on global climate change require a fundamental knowledge of how the Antarctic cryosphere (ice sheets, ice shelves, and sea ice has evolved, not only in recent times but also during earlier geological periods when global temperature and atmospheric CO2 levels were similar to what might be reached by the end of this century. ANDRILL’s integrated science approach willuse stratigraphic drilling, coring, and multi-proxy core analysis combined with geophysical surveys and numerical modeling to study the Cenozoic history of Antarctic climate and ice sheets, the evolution of polar biota, Antarctic tectonism, and Antarctica’s role in the evolution of Earth’s ocean–climate system.

  12. Chemical composition of fresh snowfalls at Palmer Station, Antarctica

    Science.gov (United States)

    DeFelice, T. P.

    A first time investigation was performed to establish a chemical baseline for snowfall at Palmer Station Antarctica (64°46'S, 64°05'W) since there was no such record. A chemical baseline for snow could be use to validate climate change studies based on ice core analyses. The snow samples contained (from high to low mass concentration) total organic carbon, chloride, inorganic carbon, sodium, sulfate, magnesium, calcium, potassium, fluoride, ammonium, and nitrate, excluding hydrogen and hydroxide. The pH of these samples ranged between 4.0-6.2. The relatively low nitrate and relatively high sulfate concentrations found in our samples are consistent with the results of other studies for this region of Antarctica. The ions and pH do not appear to favor a particular wind direction during this period. The total deposition of sulfate and flouride via snowfall between 10 January and 10 February is conservatively estimated to be 4.78 and 1.3 kg km -2, respectively.

  13. Ocean mixing beneath Pine Island Glacier ice shelf, West Antarctica

    Science.gov (United States)

    Kimura, Satoshi; Jenkins, Adrian; Dutrieux, Pierre; Forryan, Alexander; Naveira Garabato, Alberto C.; Firing, Yvonne

    2016-12-01

    Ice shelves around Antarctica are vulnerable to an increase in ocean-driven melting, with the melt rate depending on ocean temperature and the strength of flow inside the ice-shelf cavities. We present measurements of velocity, temperature, salinity, turbulent kinetic energy dissipation rate, and thermal variance dissipation rate beneath Pine Island Glacier ice shelf, West Antarctica. These measurements were obtained by CTD, ADCP, and turbulence sensors mounted on an Autonomous Underwater Vehicle (AUV). The highest turbulent kinetic energy dissipation rate is found near the grounding line. The thermal variance dissipation rate increases closer to the ice-shelf base, with a maximum value found ˜0.5 m away from the ice. The measurements of turbulent kinetic energy dissipation rate near the ice are used to estimate basal melting of the ice shelf. The dissipation-rate-based melt rate estimates is sensitive to the stability correction parameter in the linear approximation of universal function of the Monin-Obukhov similarity theory for stratified boundary layers. We argue that our estimates of basal melting from dissipation rates are within a range of previous estimates of basal melting.

  14. Properties of soils in Grove Mountains, East Antarctica

    Institute of Scientific and Technical Information of China (English)

    LI; Xiaoli(李潇丽); LIU; Xiaohan(刘小汉); JU; Yitai(琚宜太); HUANG; Feixin(黄费新)

    2003-01-01

    Three cold desert soil sites were first found in the southern Mount Harding, GroveMountains, East Antarctica. The soils are characteristics of the widespread occurrence of surfacedesert pavement, abundant water-soluble salts, strongly stained upper portion of soil profile,slightly acid and negligible organic matter content. A 1:5 soil-water extracts analysis indicates thatthe dominant cations are Mg2+ and Na+, followed by Ca2+ and K+, and the main anion is SO42-, thenCl- and NO-3. The accumulation of water-soluble salts indicates ion transportation in the frigid andarid Antarctica environment. The distribution of the salts is related to the maximum content ofmoisture and clay mineral. Clay fraction migration occurs in the soils, which is different from that ofother cold desert soils. The upper horizons of some profiles are generally stained, namely rubifica-tion, primarily because of the weathering of iron-bearing minerals. The reddish hues of cold desertsoils have been attributed to relatively high concentrations of dithionite-extractable Fe (Fed). Theweathering features of soils suggest that the soil age of this area is 0.5-3.5 Ma. No remnants ofglaciations were found on the soil sites of Mount Harding, which suggests that the Antarctic glaci-ations have not reached the soil sites since at least 0.5 Ma, even during the Last Glacial Maxi-mum.

  15. The larval alimentary canal of the Antarctic insect, Belgica antarctica.

    Science.gov (United States)

    Nardi, James B; Miller, Lou Ann; Bee, Charles Mark; Lee, Richard E; Denlinger, David L

    2009-09-01

    On the Antarctica continent the wingless midge, Belgica antarctica (Diptera, Chironomidae) occurs further south than any other insect. The digestive tract of the larval stage of Belgica that inhabits this extreme environment and feeds in detritus of penguin rookeries has been described for the first time. Ingested food passes through a foregut lumen and into a stomodeal valve representing an intussusception of the foregut into the midgut. A sharp discontinuity in microvillar length occurs at an interface separating relatively long microvilli of the stomodeal midgut region, the site where peritrophic membrane originates, from the midgut epithelium lying posterior to this stomodeal region. Although shapes of cells along the length of this non-stomodeal midgut epithelium are similar, the lengths of their microvilli increase over two orders of magnitude from anterior midgut to posterior midgut. Infoldings of the basal membranes also account for a greatly expanded interface between midgut cells and the hemocoel. The epithelial cells of the hindgut seem to be specialized for exchange of water with their environment, with the anterior two-thirds of the hindgut showing highly convoluted luminal membranes and the posterior third having a highly convoluted basal surface. The lumen of the middle third of the hindgut has a dense population of resident bacteria. Regenerative cells are scattered throughout the larval midgut epithelium. These presumably represent stem cells for the adult midgut, while a ring of cells, marked by a discontinuity in nuclear size at the midgut-hindgut interface, presumably represents stem cells for the adult hindgut.

  16. Transit Search from Antarctica and Chile - Comparison and Combination

    CERN Document Server

    Fruth, T; Csizmadia, Sz; Dreyer, C; Eigmüller, P; Erikson, A; Kabath, P; Pasternacki, T; Rauer, H; Titz-Weider, R; Abe, L; Agabi, A; Gonçalves, I; Guillot, T; Mékarnia, D; Rivet, J -P; Crouzet, N; Chini, R; Lemke, R; Murphy, M

    2014-01-01

    Observing sites at the East-Antarctic plateau are considered to provide exceptional conditions for astronomy. The aim of this work is to assess its potential for detecting transiting extrasolar planets through a comparison and combination of photometric data from Antarctica with time series from a midlatitude site. During 2010, the two small aperture telescopes ASTEP 400 (Dome C) and BEST II (Chile) together performed an observing campaign of two target fields and the transiting planet WASP-18b. For the latter, a bright star, Dome C appears to yield an advantageous signal-to-noise ratio. For field surveys, both Dome C and Chile appear to be of comparable photometric quality. However, within two weeks, observations at Dome C yield a transit detection efficiency that typically requires a whole observing season in Chile. For the first time, data from Antarctica and Chile have been combined to extent the observational duty cycle. This approach is both feasible in practice and favorable for transit search, as it i...

  17. Reactive chlorine chemistry in the boundary layer of coastal Antarctica

    Science.gov (United States)

    Zielcke, Johannes; Poehler, Denis; Friess, Udo; Hay, Tim; Eger, Philipp; Kreher, Karin; Platt, Ulrich

    2015-04-01

    A unique feature of the polar troposphere is the strong impact of halogen photochemistry, in which reactive halogen species are responsible for ozone depletion as well as the oxidation of elemental mercury and dimethyl sulphide. The source, however, as well as release and recycling mechanisms of these halogen species - for some species even abundances - are far from being completely known, especially of chlorine and iodine compounds. Here we present active long-path differential optical absorption spectroscopy (LP-DOAS) measurements conducted during austral spring 2012 at Ross Island, Antarctica, observing several species (BrO, O3, NO2, IO, ClO, OBrO, OClO, OIO, I2, CHOCHO, HCHO, HONO). For the first time, ClO was detected and quantified in the marine boundary layer of coastal Antarctica, with typical mixing ratios around 20 pptv and maxima around 50 pptv. Meteorological controls on the mixing ratio of ClO as well as the interplay with other halogen compounds will be discussed, such as the lack of observed OClO (< 1 pptv). The results seem to reflect previously in chamber studies observed dependences on ozone levels and solar irradiance.

  18. Lateral and vertical distribution of soil organic carbon in recently deglaciated areas of Elephant Point (Livingstone island, Maritime Antarctica)

    Science.gov (United States)

    Navas, Ana; Oliva, Marc; Ruiz-Fernández, Jesús; Quijano, Laura; Gaspar, Leticia; Lizaga, Iván

    2017-04-01

    In Maritime Antarctica important environmental changes are affecting ice-free environments of the South Shetland Islands and the northern Antarctica Peninsula. In the Elephant Point Peninsula (Livingstone Island) a rapid glacier retreat during the last decades has exposed already around 20% of its 1.16 km2 surface. Despite soil development is taken place in these new created lands little is known on the characteristics and properties of soils on different parent materials and landforms. One of the main soil properties is the organic carbon but the SOC pool dynamics in Antarctica environments is still poorly understood. This work aims to gain knowledge on the lateral and vertical variations of soil organic carbon (SOC) and organic carbon fractions in surface profiles that have been exposed succeeding the phases of glacier retreat. To this purpose a sampling scheme following the direction of the glacier retreat was established along a moraine extending from the western to the eastern coastlines and a sequence of Holocene marine terraces in Elephant Point. To assess the lateral and vertical variations of SOC and SOC fractions a total of 10 sites were sampled until a depth of 12 cm then sectioned at 3 cm depth intervals. According to its chemical stability and turnover times, SOC can be divided into the active carbon fraction (ACF) composed of labile aliphatic and carboxyl groups with turnover rates of days to few years and a more stable refractory aromatic carbon fraction (SCF) with turnover rates from few years to centuries, highly resistant to microbial and chemical decomposition. The SOC content (%) was measured at 550 °C by the dry combustion method using a LECO, RC-612 multiphase carbon analyser. For the characterization of the active and stable carbon fractions the temperature of the furnace was stepped at 350 °C and 550 °C, respectively. Estimates of SOC and SOC fractions inventories (kg m-2) were done to assess their stocks on the different landforms. SOC

  19. A Combined Observational and Modeling Approach to Study Modern Dust Transport from the Patagonia Desert to East Antarctica

    Science.gov (United States)

    Gasso, S.; Stein, A.; Marino, F.; Castellano, E.; Udisti, R.; Ceratto, J.

    2010-01-01

    The understanding of present atmospheric transport processes from Southern Hemisphere (SH) landmasses to Antarctica can improve the interpretation of stratigraphic data in Antarctic ice cores. In addition, long range transport can deliver key nutrients normally not available to marine ecosystems in the Southern Ocean and may trigger or enhance primary productivity. However, there is a dearth of observational based studies of dust transport in the SH. This work aims to improve current understanding of dust transport in the SH by showing a characterization of two dust events originating in the Patagonia desert (south end of South America). The approach is based on a combined and complementary use of satellite retrievals (detectors MISR, MODIS, GLAS ,POLDER, OMI,), transport model simulation (HYSPLIT) and surface observations near the sources and aerosol measurements in Antarctica (Neumayer and Concordia sites). Satellite imagery and visibility observations confirm dust emission in a stretch of dry lakes along the coast of the Tierra del Fuego (TdF) island (approx.54deg S) and from the shores of the Colihue Huapi lake in Central Patagonia (approx.46deg S) in February 2005. Model simulations initialized by these observations reproduce the timing of an observed increase in dust concentration at the Concordia Station and some of the observed increases in atmospheric aerosol absorption (here used as a dust proxy) in the Neumayer station. The TdF sources were the largest contributors of dust at both sites. The transit times from TdF to the Neumayer and Concordia sites are 6-7 and 9-10 days respectively. Lidar observations and model outputs coincide in placing most of the dust cloud in the boundary layer and suggest significant de- position over the ocean immediately downwind. Boundary layer dust was detected as far as 1800 km from the source and approx.800 km north of the South Georgia Island over the central sub-Antarctic Atlantic Ocean. Although the analysis suggests the

  20. Properties of Spray Dried Food and Spray Drying Characteristics

    Science.gov (United States)

    Katoh, Fumio

    The following conclusions are obtained, studying properties of spray dried food and drying characteristics. (a) Dried particles are similar to spray droplets in size distribution (y=2.5), and particle count distribution is arranged as (dn/dx = ae-bx). (b) The ratio of the particle diameters before and after drying is calculated with moisture before and after drying, and porosity is given as (εp = ww4). (c) The standard drying method is presented to evaluate accurately drying problems at a certain standard. (d) Equilibrium moisture at 20 up to 100°C are summarized in terms of adsorption potential. (e) It makes clear that calulation based on the theory of residence time and drying time represents well complex spray drying characteristics.

  1. 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 ... when I sleep? Feb 10, 2016 Leer en Español: ¿Qué Es el Ojo Seco? Find an Ophthalmologist ...

  2. Infrared Drying Parameter Optimization

    Science.gov (United States)

    Jackson, Matthew R.

    In recent years, much research has been done to explore direct printing methods, such as screen and inkjet printing, as alternatives to the traditional lithographic process. The primary motivation is reduction of the material costs associated with producing common electronic devices. Much of this research has focused on developing inkjet or screen paste formulations that can be printed on a variety of substrates, and which have similar conductivity performance to the materials currently used in the manufacturing of circuit boards and other electronic devices. Very little research has been done to develop a process that would use direct printing methods to manufacture electronic devices in high volumes. This study focuses on developing and optimizing a drying process for conductive copper ink in a high volume manufacturing setting. Using an infrared (IR) dryer, it was determined that conductive copper prints could be dried in seconds or minutes as opposed to tens of minutes or hours that it would take with other drying devices, such as a vacuum oven. In addition, this study also identifies significant parameters that can affect the conductivity of IR dried prints. Using designed experiments and statistical analysis; the dryer parameters were optimized to produce the best conductivity performance for a specific ink formulation and substrate combination. It was determined that for an ethylene glycol, butanol, 1-methoxy 2- propanol ink formulation printed on Kapton, the optimal drying parameters consisted of a dryer height of 4 inches, a temperature setting between 190 - 200°C, and a dry time of 50-65 seconds depending on the printed film thickness as determined by the number of print passes. It is important to note that these parameters are optimized specifically for the ink formulation and substrate used in this study. There is still much research that needs to be done into optimizing the IR dryer for different ink substrate combinations, as well as developing a

  3. Distribution and diversity of soil microfauna from East Antarctica: assessing the link between biotic and abiotic factors.

    Directory of Open Access Journals (Sweden)

    Alejandro Velasco-Castrillón

    Full Text Available Terrestrial life in Antarctica has been described as some of the simplest on the planet, and mainly confined to soil microfaunal communities. Studies have suggested that the lack of diversity is due to extreme environmental conditions and thought to be driven by abiotic factors. In this study we investigated soil microfauna composition, abundance, and distribution in East Antarctica, and assessed correlations with soil geochemistry and environmental variables. We examined 109 soil samples from a wide range of ice-free habitats, spanning 2000 km from Framnes Mountains to Bailey Peninsula. Microfauna across all samples were patchily distributed, from complete absence of invertebrates to over 1600 specimens/gram of dry weight of soil (gdw, with highest microfauna abundance observed in samples with visible vegetation. Bdelloid rotifers were on average the most widespread found in 87% of sampled sites and the most abundant (44 specimens/gdw. Tardigrades occurred in 57% of the sampled sites with an abundance of 12 specimens/gdw. Nematodes occurred in 71% of samples with a total abundance of 3 specimens/gdw. Ciliates and mites were rarely found in soil samples, with an average abundance of 1.3 and 0.04 specimens/gdw, respectively. We found that microfaunal composition and abundance were mostly correlated with the soil geochemical parameters; phosphorus, NO3 (- and salinity, and likely to be the result of soil properties and historic landscape formation and alteration, rather than the geographic region they were sampled from. Studies focusing on Antarctic biodiversity must take into account soil geochemical and environmental factors that influence population and species heterogeneity.

  4. Distribution and Diversity of Soil Microfauna from East Antarctica: Assessing the Link between Biotic and Abiotic Factors

    Science.gov (United States)

    Velasco-Castrillón, Alejandro; Schultz, Mark B.; Colombo, Federica; Gibson, John A. E.; Davies, Kerrie A.; Austin, Andrew D.; Stevens, Mark I.

    2014-01-01

    Terrestrial life in Antarctica has been described as some of the simplest on the planet, and mainly confined to soil microfaunal communities. Studies have suggested that the lack of diversity is due to extreme environmental conditions and thought to be driven by abiotic factors. In this study we investigated soil microfauna composition, abundance, and distribution in East Antarctica, and assessed correlations with soil geochemistry and environmental variables. We examined 109 soil samples from a wide range of ice-free habitats, spanning 2000 km from Framnes Mountains to Bailey Peninsula. Microfauna across all samples were patchily distributed, from complete absence of invertebrates to over 1600 specimens/gram of dry weight of soil (gdw), with highest microfauna abundance observed in samples with visible vegetation. Bdelloid rotifers were on average the most widespread found in 87% of sampled sites and the most abundant (44 specimens/gdw). Tardigrades occurred in 57% of the sampled sites with an abundance of 12 specimens/gdw. Nematodes occurred in 71% of samples with a total abundance of 3 specimens/gdw. Ciliates and mites were rarely found in soil samples, with an average abundance of 1.3 and 0.04 specimens/gdw, respectively. We found that microfaunal composition and abundance were mostly correlated with the soil geochemical parameters; phosphorus, NO3− and salinity, and likely to be the result of soil properties and historic landscape formation and alteration, rather than the geographic region they were sampled from. Studies focusing on Antarctic biodiversity must take into account soil geochemical and environmental factors that influence population and species heterogeneity. PMID:24498126

  5. 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

  6. Quality of dry ginger (Zingiber officinale) by different drying methods.

    Science.gov (United States)

    E, Jayashree; R, Visvanathan; T, John Zachariah

    2014-11-01

    Ginger rhizomes sliced to various lengths of 5, 10, 15, 20, 30, 40, 50 mm and whole rhizomes were dried from an initial moisture content of 81.3 % to final moisture content of less than 10 % by various drying methods like sun drying, solar tunnel drying and cabinet tray drying at temperatures of 50, 55, 60 and 65 °C. Slicing of ginger rhizomes significantly reduced the drying time of ginger in all the drying methods. It was observed that drying of whole ginger rhizomes under sun took the maximum time (9 days) followed by solar tunnel drying (8 days). Significant reduction in essential oil and oleoresin content of dry ginger was found as the slice length decreased. The important constituents of ginger essential oil like zingiberene, limonene, linalool, geraniol and nerolidol as determined using a gas chromatography was also found to decrease during slicing and as the drying temperature increased. The pungency constituents in the oleoresin of ginger like total gingerols and total shogoals as determined using a reverse phase high performance liquid chromatography also showed a decreasing trend on slicing and with the increase in drying temperature. It was observed from the drying studies that whole ginger rhizomes dried under sun drying or in a solar tunnel drier retained the maximum essential oil (13.9 mg/g) and oleoresin content (45.2 mg/g) of dry ginger. In mechanical drying, the drying temperature of 60 °C was considered optimum however there was about 12.2 % loss in essential oil at this temperature.

  7. Genome and transcriptome analysis of the basidiomycetous yeast Pseudozyma antarctica producing extracellular glycolipids, mannosylerythritol lipids.

    Directory of Open Access Journals (Sweden)

    Tomotake Morita

    Full Text Available Pseudozyma antarctica is a non-pathogenic phyllosphere yeast known as an excellent producer of mannosylerythritol lipids (MELs, multi-functional extracellular glycolipids, from vegetable oils. To clarify the genetic characteristics of P. antarctica, we analyzed the 18 Mb genome of P. antarctica T-34. On the basis of KOG analysis, the number of genes (219 genes categorized into lipid transport and metabolism classification in P. antarctica was one and a half times larger than that of yeast Saccharomyces cerevisiae (140 genes. The gene encoding an ATP/citrate lyase (ACL related to acetyl-CoA synthesis conserved in oleaginous strains was found in P. antarctica genome: the single ACL gene possesses the four domains identical to that of the human gene, whereas the other oleaginous ascomycetous species have the two genes covering the four domains. P. antarctica genome exhibited a remarkable degree of synteny to U. maydis genome, however, the comparison of the gene expression profiles under the culture on the two carbon sources, glucose and soybean oil, by the DNA microarray method revealed that transcriptomes between the two species were significantly different. In P. antarctica, expression of the gene sets relating fatty acid metabolism were markedly up-regulated under the oily conditions compared with glucose. Additionally, MEL biosynthesis cluster of P. antarctica was highly expressed regardless of the carbon source as compared to U. maydis. These results strongly indicate that P. antarctica has an oleaginous nature which is relevant to its non-pathogenic and MEL-overproducing characteristics. The analysis and dataset contribute to stimulate the development of improved strains with customized properties for high yield production of functional bio-based materials.

  8. Groundwater quality in the Monterey Bay and Salinas Valley groundwater basins, California

    Science.gov (United States)

    Kulongoski, Justin T.; Belitz, Kenneth

    2011-01-01

    The Monterey-Salinas study unit is nearly 1,000 square miles and consists of the Santa Cruz Purisima Formation Highlands, Felton Area, Scotts Valley, Soquel Valley, West Santa Cruz Terrace, Salinas Valley, Pajaro Valley, and Carmel Valley groundwater basins (California Department of Water Resources, 2003; Kulongski and Belitz, 2011). These basins were grouped into four study areas based primarily on geography. Groundwater basins in the north were grouped into the Santa Cruz study area, and those to the south were grouped into the Monterey Bay, the Salinas Valley, and the Paso Robles study areas (Kulongoski and others, 2007). The study unit has warm, dry summers and cool, moist winters. Average annual rainfall ranges from 31 inches in Santa Cruz in the north to 13 inches in Paso Robles in the south. The study areas are drained by several rivers and their principal tributaries: the Salinas, Pajaro, and Carmel Rivers, and San Lorenzo Creek. The Salinas Valley is a large intermontane valley that extends southeastward from Monterey Bay to Paso Robles. It has been filled, up to a thickness of 2,000 feet, with Tertiary and Quaternary marine and terrestrial sediments that overlie granitic basement. The Miocene-age Monterey Formation and Pliocene- to Pleistocene-age Paso Robles Formation, and Pleistocene to Holocene-age alluvium contain freshwater used for supply. The primary aquifers in the study unit are defined as those parts of the aquifers corresponding to the perforated intervals of wells listed in the California Department of Public Health database. Public-supply wells are typically drilled to depths of 200 to 650 feet, consist of solid casing from the land surface to depths of about 175 to 500 feet, and are perforated below the solid casing. Water quality in the primary aquifers may differ from that in the shallower and deeper parts of the aquifer system. Groundwater movement is generally from the southern part of the Salinas Valley north towards the Monterey Bay

  9. Automatic mapping of valley networks on Mars

    Science.gov (United States)

    Molloy, I.; Stepinski, T. F.

    2007-06-01

    Martian valley networks bear some resemblance to terrestrial drainage systems, but their precise origin remains an active research topic. A limited number of valley networks have been manually mapped from images, but the vast majority remains unmapped because standard drainage mapping algorithms are inapplicable to valleys that are poorly organized and lack spatial integration. In this paper, we present a novel drainage delineation algorithm specially designed for mapping the valley networks from digital elevation data. It first identifies landforms characterized by convex tangential curvature, and then uses a series of image processing operations to separate valleys from other features having a convex form. The final map is produced by reconnecting all valley segments along drainage directions. Eight test sites on Mars are selected and manually mapped for valley networks. The algorithm is applied to the test sites and delineated networks are compared to mapped networks using a series of quantitative quality factors. We have found a good agreement between delineated and mapped networks. In the process of comparing manual and delineated networks some shortcomings of manual mapping became apparent. We argue that delineated networks are indeed of better quality than the networks manually mapped from images. Although the algorithm has been developed to study Martian surface, it may also be relevant to terrestrial geomorphology.

  10. Vertical Temperature Simulation of Pegasus Runway, McMurdo Station, Antarctica

    Science.gov (United States)

    2015-01-01

    Runway, McMurdo Station, Antarctica Co ld R eg io ns R es ea rc h an d En gi ne er in g La bo ra to ry Steven F. Daly, Robert Haehnel...Vertical Temperature Simulation of Pegasus Runway, McMurdo Station, Antarctica Steven F. Daly, Robert Haehnel, and Christopher Hiemstra Cold Regions...Engineering Support, Continuation” ERDC/CRREL TR-15-2 ii Abstract Pegasus Runway, located 13 km south of McMurdo Station, Antarctica , on the

  11. Potential for a significant deep basin geothermal system in Tintic Valley, Utah

    Science.gov (United States)

    Hardwick, C.; Kirby, S.

    2014-12-01

    The combination of regionally high heat flow, deep basins, and permeable reservoir rocks in the eastern Great Basin may yield substantial new geothermal resources. We explore a deep sedimentary basin geothermal prospect beneath Tintic Valley in central Utah using new 2D and 3D models coupled with existing estimates of heat flow, geothermometry, and shallow hydrologic data. Tintic Valley is a sediment-filled basin bounded to the east and west by bedrock mountain ranges where heat-flow values vary from 85 to over 240 mW/m2. Based on modeling of new and existing gravity data, a prominent 30 mGal low indicates basin fill thickness may exceed 2 km. The insulating effect of relatively low thermal conductivity basin fill in Tintic Valley, combined with typical Great Basin heat flow, predict temperatures greater than 150 °C at 3 km depth. The potential reservoir beneath the basin fill is comprised of Paleozoic carbonate and clastic rocks. The hydrology of the Tintic Valley is characterized by a shallow, cool groundwater system that recharges along the upper reaches of the basin and discharges along the valley axis and to a series of wells. The east mountain block is warm and dry, with groundwater levels just above the basin floor and temperatures >50 °C at depth. The west mountain block contains a shallow, cool meteoric groundwater system. Fluid temperatures over 50 °C are sufficient for direct-use applications, such as greenhouses and aquaculture, while temperatures exceeding 140°C are suitable for binary geothermal power plants. The geologic setting and regionally high heat flow in Tintic Valley suggest a geothermal resource capable of supporting direct-use geothermal applications and binary power production could be present.

  12. Visible Effects of Invisible Hidden Valley Radiation

    CERN Document Server

    Carloni, Lisa

    2010-01-01

    Assuming there is a new gauge group in a Hidden Valley, and a new type of radiation, can we observe it through its effect on the kinematic distributions of recoiling visible particles? Specifically, what are the collider signatures of radiation in a hidden sector? We address these questions using a generic SU(N)-like Hidden Valley model that we implement in Pythia. We find that in both the e+e- and the LHC cases the kinematic distributions of the visible particles can be significantly affected by the valley radiation. Without a proper understanding of such effects, inferred masses of "communicators" and of invisible particles can be substantially off.

  13. Comparing modeled and observed changes in mineral dust transport and deposition to Antarctica between the Last Glacial Maximum and current climates

    Energy Technology Data Exchange (ETDEWEB)

    Albani, Samuel [University of Siena, Graduate School in Polar Sciences, Siena (Italy); University of Milano-Bicocca, Department of Environmental Sciences, Milano (Italy); Cornell University, Department of Earth and Atmospheric Sciences, Ithaca, NY (United States); Mahowald, Natalie M. [Cornell University, Department of Earth and Atmospheric Sciences, Ithaca, NY (United States); Delmonte, Barbara; Maggi, Valter [University of Milano-Bicocca, Department of Environmental Sciences, Milano (Italy); Winckler, Gisela [Columbia University, Lamont-Doherty Earth Observatory, Palisades, NY (United States); Columbia University, Department of Earth and Environmental Sciences, New York, NY (United States)

    2012-05-15

    Mineral dust aerosols represent an active component of the Earth's climate system, by interacting with radiation directly, and by modifying clouds and biogeochemistry. Mineral dust from polar ice cores over the last million years can be used as paleoclimate proxy, and provide unique information about climate variability, as changes in dust deposition at the core sites can be due to changes in sources, transport and/or deposition locally. Here we present results from a study based on climate model simulations using the Community Climate System Model. The focus of this work is to analyze simulated differences in the dust concentration, size distribution and sources in current climate conditions and during the Last Glacial Maximum at specific ice core locations in Antarctica, and compare with available paleodata. Model results suggest that South America is the most important source for dust deposited in Antarctica in current climate, but Australia is also a major contributor and there is spatial variability in the relative importance of the major dust sources. During the Last Glacial Maximum the dominant source in the model was South America, because of the increased activity of glaciogenic dust sources in Southern Patagonia-Tierra del Fuego and the Southernmost Pampas regions, as well as an increase in transport efficiency southward. Dust emitted from the Southern Hemisphere dust source areas usually follow zonal patterns, but southward flow towards Antarctica is located in specific areas characterized by southward displacement of air masses. Observations and model results consistently suggest a spatially variable shift in dust particle sizes. This is due to a combination of relatively reduced en route wet removal favouring a generalized shift towards smaller particles, and on the other hand to an enhanced relative contribution of dry coarse particle deposition in the Last Glacial Maximum. (orig.)

  14. 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

  15. 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.

  16. Crustal structure across the Filchner Ronne Shelf, Antarctica

    Science.gov (United States)

    Herter, U.; Jokat, W.

    2012-04-01

    Crustal structure across the Filchner Ronne Shelf, Antarctica U. Herter, W. Jokat One large gap in understanding the tectonic evolution of Antarctica beside the few rock outcrops on the continent is the missing information on crustal thickness along its margins but also in its interior. E.g., the few marine deep seismic lines are located mainly along the Antarctic Peninsula/Pacific margin, but for most of the East Antarctic margins such information is not available. In this contribution we concentrate on one of the most remote areas in Antarctica, the Filchner Ronne Shelf (FRS). The area is underlain by approximately 12 km of sediments, but its crustal fabric is questionable. Thus, some existing deep seismic sounding data were modeled and reinterpreted. Especially, data gathered in 1995 have been analyzed, and a more detailed 2D P-wave velocity model has been calculated. For the profiles in total 12 RefTek stations each with nine geophone chains were placed on the ice shelf and 3175 airgun shots along a 480 km transect were fired by two 32 l BOLT-Airguns each 60 s. Signals were recorded up to distances of 180 km. Due to the ice coverage it was not possible to acquire the data without gaps or along straight lines, which caused some difficulties in the modeling process. Furthermore, in the new model all data from older experiments of the AWI and Soviet Antarctic expeditions acquired with dynamite sources were incorporated. The model shows a sedimentary basin with a thickness up to 12 km and a large velocity inversion in a deeper sediment unit. The crustal thickness varies from 40 km beneath the Antarctic Peninsula, and 14 km of basement in the center part of the profile. Towards Berkner Island the crust thickens again, but the top of the basement is still 11 km deep. The lower crustal velocities range between 6.8 and 7.2 km/s. We interpret the crustal structure as clear evidence for the presence of a failed rift. The initial stretching of the continental crust

  17. Anaerobic psychrophiles from Lake Zub and Lake Untersee, Antarctica

    Science.gov (United States)

    Townsend, Alisa; Pikuta, Elena V.; Guisler, Melissa; Stahl, Sarah; Hoover, Richard B.

    2009-08-01

    The study of samples from Antarctica 2008 and 2009 expeditions organized and successfully conducted by Richard Hoover led to the isolation of diverse anaerobic strains with psychrotolerant and psychrophilic physiology. Due to the fact that Lake Untersee has never been subject to microbiological study, this work with the samples has significant and pioneering impact to the knowledge about the biology of this unique ecosystem. Also, the astrobiological significance for the study of these ecosystems is based on new findings of ice covered water systems on other bodies of our solar system. Anaerobic psychrotolerant strain LZ-22 was isolated from a frozen sample of green moss with soils around the rhizosphere collected near Lake Zub in Antarctica. Morphology of strain LZ-22 was observed to be motile, rod shaped and spore-forming cells with sizes 1 x 5-10 μm. This new isolate is a mesophile with the maximum temperature of growth at 40°C. Strain LZ-22 is able to live on media without NaCl and in media with up to 7 % (w/v) NaCl. It is catalase negative and grows only on sugars with the best growth rate being on lactose. The strain is a neutrophile and grows between pH 5 and 9.0 with the optimum at 7.8. Another two strains UL7-96mG and LU-96m7P were isolated from deep water samples of Lake Untersee. Proteolytic strain LU-96m7P had a truly psychrophilic nature and refused to grow at room temperature. Sugarlytic strain UL7-96mG was found to be psychrotolerant, but its rate of growth at 3°C was very high compared with other mesophiles. Two homoacetogenic psychrophilic strains A7AC-96m and AC-DS7 were isolated and purified from samples of Lake Untersee; both of them are able to grow chemolithotrophically on H2+CO2. In the presence of lactate, these strains are able to grow only at 0-18 °C, and growth at 22 °C was observed only with yeast extract stimulation. In this paper, physiological and morphological characteristics of novel psychrophilic and psychrotolerant isolates

  18. Antarctica, supercontinents and the palaeogeography of the Cambrian 'explosion'

    Science.gov (United States)

    Dalziel, Ian

    2014-05-01

    Laurentia is bordered by latest Precambrian-Cambrian rifted margins and must therefore have been located within a Precambrian supercontinent. Geochronologic and geochemical evidence indicates that it was attached to parts of the East Antarctic craton within the Rodinian supercontinent in the late Mesoproterozoic. The Mawson craton of Antarctica rifted from the proto-Pacific margin of Laurentia during the Neooproterozoic, colliding with the present 'southern cone' of Laurentia at ~600 Ma along the Shackleton Range suture zone as Gondwana and Laurentia amalgamated to form the ephemeral Pannotia supercontinental assembly at the end of the Precambrian. The abrupt appearance of almost all animal phyla in the fossil record is often colloquially referred to as the Cambrian 'explosion' of life on Earth. It is also named 'Darwin's dilemma,' as he appreciated that this seemingly mysterious event posed a major problem for his theory of evolution by natural selection. It coincided with a time of major marine transgression over all the continents. Although the metazoan 'explosion' is now seen as more protracted than formerly recognized, it is still regarded one of the most critical events in the history of the biosphere. One of the most striking aspects of the earliest Cambrian fossils is geographic differentiation. In particular, the first benthic trilobite faunas on Laurentia, ancestral North America, and the newly amalgamated southern supercontinent of Gondwana are distinctly different. This has led to the suggestion of an unknown vicariant event intervening between an ancestral trilobite clade and higher members that are represented in the fossil record, possibly one related to the breakup of a supercontinent. Igneous rocks along the Panthalassic margin of Gondwana, including South America, southernmost Africa and the Ellsworth-Whitmore crustal block of Antarctica, and along the proto-Appalachian margin of Laurentia indicate that final separation of Laurentia from

  19. New Views of East Antarctica- from Columbia to Gondwana

    Science.gov (United States)

    Ferraccioli, F.; Forsberg, R.; Aitken, A.; Young, D. A.; Blankenship, D. D.; Bell, R. E.; Finn, C.; Martos, Y. M.; Armadillo, E.; Jacobs, J.; Ebbing, J.; Eagles, G.; Jokat, W.; Jordan, T. A.; Ruppel, A.; Läufer, A.; Dalziel, I. W. D.

    2015-12-01

    East Antarctica is a keystone in the Gondwana, Rodinia and the Columbia supercontinents. Recent aerogeophysical research, augmented by satellite magnetic, gravity and seismological data is unveiling the crustal architecture of the continent. This is helping comprehend the impact of supercontinental processes such as subduction, accretion, rifting and intraplate tectonics on its evolution. A mosaic of Precambrian basement provinces is apparent in interior East Antarctica (Ferraccioli et al., 2011, Nature). A major suture separates the Archean-Neoproterozoic Ruker Province from an inferred Grenvillian-age orogenic Gamburtsev Province with remarkably thick crust (up to 60 km thick) and thick lithosphere (over 200 km thick). The age of the suturing and its linkages with supercontinental assembly is debated with both Rodinia and Gondwana candidates being proposed. Further east, magnetic highs delineate a Paleo to Mesoproterozoic Nimrod-South Pole igneous province (Goodge and Finn, 2010 JGR) that flanks a composite Mawson Continent- including the Gawler Craton of South Australia (Aitken et al., 2014 GRL). An over 1,900 km long magnetic and gravity lineament is imaged along the western flank of the Wilkes Subglacial Basin and is interpreted here as a major Paleoproterozoic suture zone linked to the collision of Laurentia and East Antarctica within Columbia. The proposed suture played a pivotal role helping localise Neoproterozoic Rodinia rifted margin evolution and forming a backstop for the Ross-Delamerian cycle of Gondwana amalgamation. Aeromagnetic and gravity imaging help determine the extent of a Keweenawan-age (ca 1.1 Ga) large igneous province in the Coats Land Block -isotopically tied with the Mid-Continent Rift System of Laurentia (Loewy et al., 2011 Geology). Imprints of Grenvillian magmatic arc accretion link together the Namaqua-Natal and Maud belts in South Africa and Dronning Maud Land within Rodinia. The aeromagnetically distinct Southeast Dronning Maud

  20. Anaerobic Psychrophiles from Lake Zub and Lake Untersee, Antarctica

    Science.gov (United States)

    Townsend, Alisa; Pikuta, Elena V.; Guisler, Melissa; Stahl, Sarah; Hoover, Richard B.

    2009-01-01

    The study of samples from Antarctica 2008 and 2009 expeditions organized and successfully conducted by Richard Hoover led to the isolation of diverse anaerobic strains with psychrotolerant and psychrophilic physiology. Due to the fact that Lake Untersee has never been subject to microbiological study, this work with the samples has significant and pioneering impact to the knowledge about the biology of this unique ecosystem. Also, the astrobiological significance for the study of these ecosystems is based on new findings of ice covered water systems on other bodies of our solar system. Anaerobic psychrotolerant strain LZ-22 was isolated from a frozen sample of green moss with soils around the rhizosphere collected near Lake Zub in Antarctica. Morphology of strain LZ-22 was observed to be motile, rod shaped and spore-forming cells with sizes 1 x 5-10 micron. This new isolate is a mesophile with the maximum temperature of growth at 40C. Strain LZ-22 is able to live on media without NaCl and in media with up to 7% (w/v) NaCl. It is catalase negative and grows only on sugars with the best growth rate being on lactose. The strain is a neutrophile and grows between pH 5 and 9.0 with the optimum at 7.8. Another two strains UL7-96mG and LU-96m7P were isolated from deep water samples of Lake Untersee. Proteolytic strain LU-96m7P had a truly psychrophilic nature and refused to grow at room temperature. Sugarlytic strain UL7-96mG was found to be psychrotolerant, but its rate of growth at 3C was very high compared with other mesophiles. Two homoacetogenic psychrophilic strains A7AC-96m and AC-DS7 were isolated and purified from samples of Lake Untersee; both of them are able to grow chemolithotrophically on H2+CO2. In the presence of lactate, these strains are able to grow only at 0-18C, and growth at 22C was observed only with yeast extract stimulation. In this paper, physiological and morphological characteristics of novel psychrophilic and psychrotolerant isolates from

  1. 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.

  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. 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.

  4. Distributions of larval and juvenile/adult stages of the Antarctic myctophid fish, Electrona antarctica, off Wilkes Land in East Antarctica

    Science.gov (United States)

    Moteki, Masato; Fujii, Kentaro; Amakasu, Kazuo; Shimada, Keishi; Tanimura, Atsushi; Odate, Tsuneo

    2017-06-01

    Myctophid fish are an important component of the Southern Ocean food web because of their very high biomass. This study investigated the spatial distributions of larval and juvenile/adult stages of the Antarctic myctophid Electrona antarctica. Fish were sampled in January 2011 and 2012 on a transect along 140°E and in January 2013 along 110°E using two different opening/closing net systems. In total, 1075 specimens of E. antarctica were collected: 948 larvae, 127 juveniles/adults, and 2 in the transformation stage. Most larvae were collected at 5-200 m depth, with diel vertical migration (DVM) not apparent. Larvae were mainly distributed in the Modified Circumpolar Deep Water (-1.5 °C-2.0 °C). By contrast, an analysis of the echogram at 38 kHz and discrete depth samples implied that juveniles/adults undertook DVM except in the continental slope area (65.5°S). As the distribution of krill is limited to the cold water mass (<-1.5 °C) along the continental slope, E. antarctica and krill populations are spatially separated off Wilkes Land during summer. According to the previously estimated larval period of 30-47 days, E. antarctica may spawn in late November to December in the marginal ice zone or near the sea ice edge. This study suggests that the environment related to sea ice provides a nursery ground for early stage larvae of E. antarctica.

  5. Potential impacts of damming the Juba Valley, western Somalia: Insights from geomorphology and alluvial history

    Science.gov (United States)

    Williams, Martin

    2014-05-01

    In 1988 plans were well advanced to dam the Juba River in western Somalia. The aims of the Baardheere Dam Project were to generate hydroelectric power for the capital Mogadishu, and to provide water for irrigation in the Juba Valley. A reconnaissance survey on foot along 500 km of the river upstream of the proposed dam site at Baardheere and detailed geomorphic mapping from air photos provided a basis for reconstructing the late Quaternary alluvial history of the river and for assessing the potential impact of the proposed dam. The Juba River rises in the Ethiopian Highlands and is the only river in Somalia that flows to the sea. Its history reflects climatic events in Ethiopia, where the Rift Valley lakes were very low during the LGM (21±2 ka), and high for about 5, 000 years before and after then. Cave deposits in Somalia indicate wetter conditions at 13, 10, 7.5 and 1.5 ka. Alluvial terraces in the Juba Valley range in age from late Pleistocene to late Holocene but only attain a few metres above the present floodplain. This is because the dry tributary valleys contain limestone caves and fissures that divert any high flows from the parent river underground, a process not known when the project was first approved. The oldest preserved terrace was cemented by calcrete by 40 ka. Alluvial gravels were deposited at the outlet of dry tributary valleys during times of episodic high-energy flow between 26 ka and 28 ka. Finely laminated shelly sands accumulated at 10 ka to form the 5 m terrace. The 2 m terrace was laid down 3.2 ka ago as a slackwater deposit. The lack of high-level alluvial terraces raises doubts over plans to dam the river, since rapid leakage would occur from side valleys and the reservoir would not attain the height needed to generate hydroelectric power. It would submerge all existing arable land along the river. Finally, the presence in the late Holocene alluvium of the sub-fossil gastropods Bulinus truncatus and Biomphalaria pfeifferi, which are

  6. Drying characteristics and kinetics of fluidized bed dried potato

    OpenAIRE

    S.B. BAKAL; K.H. GEDAM; Sharma, G. P.

    2008-01-01

    In developed countries, more than 50% potatoes are consumed as processed products. As drying is the vital phenomenon in processing, it is necessary to investigate the drying characteristics and its kinetics. In this experimental study, drying kinetics of Potato in two different shape of cuboidal & cylindrical with three aspect ratio was investigated as a function of drying conditions. Experiments were conducted using air temperatures of 50, 60 and 70 ºC, at velocity of 7 ms-1. The experimenta...

  7. 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.

  8. Drying of complex suspensions

    OpenAIRE

    Xu, Lei; Bergés, Alexis; Lu, Peter J.; Studart, André R.; Schofield, Andrew B.; Oki, Hidekazu; Davies, Simon; Weitz, David A.

    2010-01-01

    We investigate the 3D structure and drying dynamics of complex mixtures of emulsion droplets and colloidal particles, using confocal microscopy. Air invades and rapidly collapses large emulsion droplets, forcing their contents into the surrounding porous particle pack at a rate proportional to the square of the droplet radius. By contrast, small droplets do not collapse, but remain intact and are merely deformed. A simple model coupling the Laplace pressure to Darcy's law correctly estimates ...

  9. Dynamics and mass balance of Taylor Glacier, Antarctica: 2. Force balance and longitudinal coupling

    Science.gov (United States)

    Kavanaugh, J. L.; Cuffey, K. M.

    2009-11-01

    Taylor Glacier, Antarctica, exemplifies an ice sheet outlet that flows through a region of rugged topography and dry climate. In contrast to other well-studied outlets, Taylor Glacier moves very slowly, despite a thickness of order 1 km and driving stresses averaging 1.5 bars. Here we analyze new measurements of glacier geometry and surface velocity to elucidate flow dynamics of Taylor Glacier. Force balance and basal temperatures are calculated at six locations along the glacier's length using an algorithm developed for this study. The effects of stress-gradient coupling on longitudinal flow variations are also examined; we ask whether Kamb and Echelmeyer's (1986) linearized theory adequately describes the observed response of flow to large-amplitude variations in driving stress. The force balance calculations indicate that no basal motion is needed to explain the observed flow of Taylor Glacier. Inferred basal temperatures are within a few degrees of the melting point in regions of kilometer-thick ice and well below the melting point elsewhere; deformation of subfreezing ice largely controls the flow of Taylor Glacier. Basal drags are mostly in the range 0.9 to 1.2 bars, and lateral drags are in the range 0.2 to 0.5 bar. Stress-gradient coupling strongly reduces the variability of velocities along the glacier. The velocity variations can be described as the convolution of a forcing function with a spatial filter, as Kamb and Echelmeyer suggested, but the form of the forcing function differs from the theoretical relation derived for small-amplitude perturbations (the power on driving stress is one, not three).

  10. Thirteen years of integrated precipitable water derived by GPS at Mario Zucchelli Station, Antarctica

    Directory of Open Access Journals (Sweden)

    Pierguido Sarti

    2013-06-01

    Full Text Available Since 1998, the Italian Antarctic Programme has been funding space geodetic activities based on the use of episodic and permanent global positioning system (GPS observations. As well as their exploitation in geodynamics, these data can be used to sense the atmosphere and to retrieve and monitor its water vapor content and variations. The surface pressure p and temperature Ts at the GPS tracking sites are necessary to compute the zenith hydrostatic delay (ZHD, and consequently, the precipitable water. At sites where no surface information is recorded, the p and Ts values can be retrieved from, e.g., global numerical weather prediction models. Alternatively, the site-specific ZHD values can be computed by interpolation of the ZHD values provided in a grid model (2.5° × 2.0°. We have processed the data series of the permanent GPS site TNB1 (Mario Zucchelli Station, Antarctica from 1998 to 2010, with the purpose of comparing the use of grid ZHD values as an alternative to the use of real surface records. With these approaches, we estimate almost 7 × 104 hourly values of precipitable water over 13 years, and we find discrepancies that vary between 1.8 (±0.2 mm in summer and 3.3 (±0.5 mm in winter. In addition, the discrepancies of the two solutions show a clear seasonal dependency. Radiosounding measurements were used to derive an independent series of precipitable water. These agree better with the GPS precipitable water derived from real surface data. However, the GPS precipitable water time series is dry biased, as it is ca. 77% of the total moisture measured by the radiosoundings. Both the GPS and radiosounding observations are processed through the most up-to-date strategies, to reduce known systematic errors.

  11. Dehydration, rehydration, and overhydration alter patterns of gene expression in the Antarctic midge, Belgica antarctica.

    Science.gov (United States)

    Lopez-Martinez, Giancarlo; Benoit, Joshua B; Rinehart, Joseph P; Elnitsky, Michael A; Lee, Richard E; Denlinger, David L

    2009-05-01

    We investigated molecular responses elicited by three types of dehydration (fast, slow and cryoprotective), rehydration and overhydration in larvae of the Antarctic midge, Belgica antarctica. The larvae spend most the year encased in ice but during the austral summer are vulnerable to summer storms, osmotic stress from ocean spray and drying conditions due to wind and intense sunlight. Using suppressive subtractive hybridization (SSH), we obtained clones that were potentially responsive to dehydration and then used northern blots to evaluate the gene's responsiveness to different dehydration rates and hydration states. Among the genes most responsive to changes in the hydration state were those encoding heat shock proteins (smHsp, Hsp70, Hsp90), antioxidants (superoxide dismutase, catalase), detoxification (metallothionein, cytochrome p450), genes involved in altering cell membranes (fatty acid desaturase, phospholipase A2 activating protein, fatty acyl CoA desaturase) and the cytoskeleton (actin, muscle-specific actin), and several additional genes including a zinc-finger protein, pacifastin and VATPase. Among the three types of dehydration evaluated, fast dehydration elicited the strongest response (more genes, higher expression), followed by cryoprotective dehydration and slow dehydration. During rehydration most, but not all, genes that were expressed during dehydration continued to be expressed; fatty acid desaturase was the only gene to be uniquely upregulated in response to rehydration. All genes examined, except VATPase, were upregulated in response to overhydration. The midge larvae are thus responding quickly to water loss and gain by expressing genes that encode proteins contributing to maintenance of proper protein function, protection and overall cell homeostasis during times of osmotic flux, a challenge that is particularly acute in this Antarctic environment.

  12. 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 operate...

  13. Valley-filtered edge states and quantum valley Hall effect in gated bilayer graphene.

    Science.gov (United States)

    Zhang, Xu-Long; Xu, Lei; Zhang, Jun

    2017-05-10

    Electron edge states in gated bilayer graphene in the quantum valley Hall (QVH) effect regime can carry both charge and valley currents. We show that an interlayer potential splits the zero-energy level and opens a bulk gap, yielding counter-propagating edge modes with different valleys. A rich variety of valley current states can be obtained by tuning the applied boundary potential and lead to the QVH effect, as well as to the unbalanced QVH effect. A method to individually manipulate the edge states by the boundary potentials is proposed.

  14. 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.

  15. Hydrothermal system of Long Valley caldera, California

    Energy Technology Data Exchange (ETDEWEB)

    Sorey, M.L.; Lewis, R.E.; Olmsted, F.H.

    1978-01-01

    The geologic and hydrologic setting of the hydrothermal system are described. The geochemical and thermal characteristics of the system are presented. A mathematical model of the Long Valley caldera is analyzed. (MHR)

  16. 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 an...

  17. Woodcock "Roundup" 2001 at Canaan Valley NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — In an effort to make a more complete census of breeding American woodcock in the Canaan Valley, a volunteer survey was performed in April. The idea was to coordinate...

  18. 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...

  19. Goldstone Apple Valley Radio Telescope Project.

    Science.gov (United States)

    Ibe, Mary; MacLaren, Dave

    2003-01-01

    Describes the Goldstone Apple Valley Radio Telescope (GAVRT) project as a way of teaching astronomy concepts to middle school students. The project provides students opportunities to work with professional scientists. (SOE)

  20. Woodcock "Roundup" 2004 at Canaan Valley NWR

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — On April 24, 2004 the refuge sponsored the fourth annual ''woodcock round up", a volunteer event to perform a woodcock survey in Canaan Valley. The event was started...