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  • 1
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    Spatial and temporal patterns of snow accumulation and aerial ablation across the McMurdo Dry Valleys, Antarctica (2012)
    Wiley
    Details
    Publication Date: 2012-05-19
    Description: Snow in the McMurdo Dry Valleys is potential source of moisture for subnivian soils in a cold desert ecosystem. In a water-limited environment, enhanced soil moisture is expected to provide more favorable conditions for subnivian soil communities. In addition, snow cover insulates the underlying soil from air temperature extremes. Quantifying the spatial and temporal patterns of seasonal snow accumulation and ablation is necessary to understand these dynamics. Repeat high-resolution imagery acquired for the 2009–2010 austral summer was used to map the seasonal distribution of snow across Taylor and Wright Valleys, Southern Victorialand Antarctica. An edge detection algorithm was used to perform an object-based classification of snow-covered area. Coupled with topographic parameters obtained from a 30-meter digital elevation model, unique distribution patterns were characterized for 5 regions within the neighboring valleys. Time lapses of snow distribution in each region provide insight into spatially variable aerial ablation rates (change in area of landscape covered by snow) across the region. A strong coastal to interior gradient of decreasing snow-covered area was evident for both Taylor and Wright Valleys. The surrounding regions of Lake Fryxell, Lake Hoare, Lake Bonney, Lake Brownworth, and Lake Vanda exhibited losses of snow-covered area of 9.61 km 2 (−93%), 1.63 km 2 (−72%), 1.07 km 2 (−97%), 2.60 km 2 (−82%), and 0.25 km 2 (−96%) respectively, as measured from peak accumulation in October to mid-January. Differences in aerial ablation rates within and across local regions suggest that both topographic variation and regional microclimates influence the ablation of seasonal snow cover. Copyright © 2012 John Wiley & Sons, Ltd.
    Print ISSN: 0885-6087
    Electronic ISSN: 1099-1085
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by Wiley
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  • 2
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    Implications of meltwater pulse events for soil biology and biogeochemical cycling in a polar desert (2011)
    Norwegian Polar Institute
    Details
    Publication Date: 2011-12-20
    Description: The McMurdo Dry Valleys are one of the most arid environments on Earth. Over the soil landscape for the majority of the year, biological and ecosystem processes in the dry valleys are constrained by the low temperatures and limited availability of water. The prevalence of these physical limitations in controlling biological and ecosystem processes makes the dry valleys a climatesensitive system, poised to experience substantial changes following projected future warming. Short-duration increases in summer temperatures are associated with pulses of water from melting ice reserves, including glaciers, snow and permafrost. Such pulses alter soil geochemistry by mobilizing and redistributing soil salts (via enhanced weathering, solubility and mobility), which can alter habitat suitability for soil organisms. Resulting changes in soil community composition or distribution may alter the biogeochemical processes in which they take part. Here, we review the potential impacts of meltwater pulses and present new field data documenting instances of meltwater pulse events that result from different water sources and hydrological patterns, and discuss their potential influence on soil biology and biogeochemistry. We use these examples to discuss the potential impacts of future climate change on the McMurdo Dry Valley soil ecosystem. Keywords: Water pulse; climate change; polar desert; International Polar Year; discrete warming events; soil biogeochemistry (Published: 19 December 2011) Citation: Polar Research 2011, 30 , 14555, DOI: 10.3402/polar.v30i0.14555
    Print ISSN: 0800-0395
    Electronic ISSN: 1751-8369
    Topics: Geography , Geosciences
    Published by Norwegian Polar Institute
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  • 3
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    Drug history modifies the behavioral effects of pentobarbital (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-04-15
    Description: Behavior of squirrel monkeys, maintained by the termination of stimuli associated with electric shock, was suppressed by response-dependent shock delivery. The effects of pentobarbital on this behavior depended on whether monkeys had previously received morphine. In monkeys without experience with drugs, pentobarbital increased responding. In monkeys with recent experience with morphine, however, pentobarbital resulted in a smaller increase or decrease in responding. The rate-decreasing effects of pentobarbital after a history of morphine administration could be reversed by the administration of d-amphetamine. These findings suggest that the behavioral effects of abused drugs may depend on previous experience with other drugs, even when those drugs are from a different pharmacological class.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Glowa, J R -- Barrett, J E -- DA 02658/DA/NIDA NIH HHS/ -- DA 02873/DA/NIDA NIH HHS/ -- MH 07658/MH/NIMH NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1983 Apr 15;220(4594):333-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6682244" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Behavior, Animal/*drug effects ; Dextroamphetamine/pharmacology ; Dose-Response Relationship, Drug ; Drug Interactions ; Humans ; Macaca mulatta ; Male ; Morphine/pharmacology ; Pentobarbital/*pharmacology ; Saimiri ; Substance-Related Disorders/physiopathology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 4
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    Observed trends of soil fauna in the Antarctic Dry Valleys: early signs of shifts predicted under climate change (2018)
    Wiley
    In: Ecology
    Details
    Publication Date: 2018-01-06
    Description: Long-term observations of ecological communities are necessary for generating and testing predictions of ecosystem responses to climate change. We investigated temporal trends and spatial patterns of soil fauna along similar environmental gradients in three sites of the McMurdo Dry Valleys, Antarctica, spanning two distinct climatic phases: a decadal cooling trend from the early 1990s through the austral summer of February 2001, followed by a shift to the current trend of warming summers and more frequent discrete warming events. After February 2001, we observed a decline in the dominant species (the nematode Scottnema lindsayae ) and increased abundance and expanded distribution of less common taxa (rotifers, tardigrades, and other nematode species). Such diverging responses have resulted in slightly greater evenness and spatial homogeneity of taxa. However, total abundance of soil fauna appears to be declining, as positive trends of the less common species so far have not compensated for the declining numbers of the dominant species. Interannual variation in the proportion of juveniles in the dominant species was consistent across sites, whereas trends in abundance varied more. Structural equation modeling supports the hypothesis that the observed biological trends arose from dissimilar responses by dominant and less common species to pulses of water availability resulting from enhanced ice melt. No direct effects of mean summer temperature were found, but there is evidence of indirect effects via its weak but significant positive relationship with soil moisture. Our findings show that combining an understanding of species responses to environmental change with long-term observations in the field can provide a context for validating and refining predictions of ecological trends in the abundance and diversity of soil fauna.
    Print ISSN: 0012-9658
    Electronic ISSN: 1939-9170
    Topics: Biology
    Published by Wiley on behalf of The Ecological Society of America (ESA).
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  • 5
    Electronic Resource
    Electronic Resource
    Alkaline heating of canola and rapeseed meals reduces toxicity for chicks (1998)
    Springer
    Plant foods for human nutrition 52 (1998), S. 9-15 
    Details
    ISSN: 1573-9104
    Keywords: Alkaline treatment ; Canola ; Chicks ; Glucosinolate ; Rapeseed ; Toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A simple method for improving the nutritive quality of canola and high glucosinolate rapeseed meals for monogastric animals (chicks) was developed; the meals were mixed with NaHCO3 and NH4HCO3, then heated in a conventional oven. Chicks fed untreated canola or rapeseed meals gained less weight than those fed a soybean meal diet, whereas chicks fed the alkaline-heated meals had weight gains not significantly different than those fed the soybean diet. The antithyroid effect of the untreated rapeseed meal was reduced by alkaline treatment of the meals, as shown by improved T4 and free T4 levels in chicks fed the processed products. In chicks fed untreated or alkaline-treated canola or alkaline heated rapeseed meal, all thyroid hormone levels were similar to those of birds fed the soybean meal diet. However, heart tissue of chicks fed diets containing rapeseed or canola meals showed muscle fiber degeneration, although relative heart weights were the same in all groups. Liver tissue from most of the chicks in all dietary groups appeared normal or only slightly abnormal. The nutritive value of both rapeseed and canola meals was improved by this simple processing technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008081816805
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    Paper (German National Licenses)
    Fulltext
  • 6
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    Abiotic Nitrogen Uptake in Semiarid Grassland Soils of the U.S. Great Plains (2002)
    Wiley
    Details
    Publication Date: 2002-01-01
    Print ISSN: 0361-5995
    Electronic ISSN: 1435-0661
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Wiley
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  • 7
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    Phosphorus Fractions in Soils of Taylor Valley, Antarctica (2006)
    Wiley
    Details
    Publication Date: 2006-05-01
    Print ISSN: 0361-5995
    Electronic ISSN: 1435-0661
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Wiley
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  • 8
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    Biogeochemical stoichiometry of Antarctic Dry Valley ecosystems (2007)
    American Geophysical Union
    Details
    Publication Date: 2007-02-07
    Print ISSN: 0148-0227
    Electronic ISSN: 2156-2202
    Topics: Geosciences
    Published by American Geophysical Union
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  • 9
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    A Model for Hydride Transfer in Thymidylate Synthase Based on Unnatural Amino Acid Mutagenesis (1999)
    American Chemical Society
    Details
    Publication Date: 1999-09-01
    Print ISSN: 0002-7863
    Electronic ISSN: 1520-5126
    Topics: Chemistry and Pharmacology
    Published by American Chemical Society
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  • 10
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    Solid-phase speciation of Zn in road dust sediment (2011)
    Mineralogical Society of Great Britain and Ireland
    Details
    Publication Date: 2011-10-10
    Description: X-ray absorption spectroscopy, scanning electron microscopy (SEM) and X-ray diffractometry (XRD) have been used to study the solid-phase speciation of Zn in urban road dust sediments (RDS) in Manchester, UK. X-ray absorption near-edge structure (XANES) analysis using linear combination modelling suggest that the soluble species Zn(NO3)2{middle dot}6H2O and ZnCl2 represent 70-83%, and Zn-sorbed goethite 17-30%, of the Zn species present. The presence of goethite is not corroborated by extended X-ray absorption fine structure (EXAFS) modelled first shell scattering Zn-O distances of 2.01-2.03 A, but this may be due to distortion of the Zn octahedra on the goethite surface, or the existence of Zn-sorbed species with other metal hydrous oxides, as inferred by the EXAFS-modelled second shell Fe and Al scatterers. Analysis by EXAFS also suggests that metallic Zn-Cu-Sn-Pb and Zn-silicate phases are present in the RDS, and this is corroborated by SEM and XRD. Other phases suggested by EXAFS include ZnO, franklinite, Zn-sorbed birnessite and zinc formate. Differences between the XANES and other results suggest that model compounds such as Zn-bearing phyllosilicates and metallic Zn phases may have been missing from the XANES fitting. Long-term low-level exposure to the RDS Zn phases identified may lead to an increased risk of cardiovascular or pulmonary diseases.
    Print ISSN: 0026-461X
    Electronic ISSN: 1471-8022
    Topics: Geosciences
    Published by Mineralogical Society of Great Britain and Ireland
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