Bulletin of Glaciological Research
Online ISSN : 1884-8044
Print ISSN : 1345-3807
ISSN-L : 1345-3807
Volume 37
Displaying 1-5 of 5 articles from this issue
  • Tsutomu UCHIDA, Maho FURUKAWA, Takahiro KIKAWADA, Kenji YAMAZAKI, Kazu ...
    2019 Volume 37 Pages 1-9
    Published: 2019
    Released on J-STAGE: September 04, 2019

    Trehalose acts as a non-toxic cryoprotectant agent (CPA) to CHO-TRET1 cells, which are CHO-K1 cells that express the trehalose transporter. This study examines the viabilities during long-term storage at 193K of cryopreserved CHO-TRET1 cells with trehalose, and compares them to the corresponding viabilities with 10wt%-dimethyl sulfoxide (DMSO). The cryopreserved samples are selected to have a 1-week storage viability exceeding 0.7. Results show that this high viability with trehalose is maintained at the same level for about one year of storage, and gradually decrease to about 0.55±0.16 after about 2.5 years. Comparison of this result with the corresponding case with DMSO suggests that the cryoprotective ability of trehalose is slightly weaker than that of DMSO at this temperature. We discuss the effect of recrystallization of ice, and also the biological damaging, on the viabilities. Then we concluded that the cell membrane slowly degrades at 193K, with the rate being a little faster with trehalose than with DMSO.

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  • Tsutomu SUDA, Kazuki TAKIZAWA, Nobuyoshi KONISHI, Satoshi OMIYA, Shun ...
    2019 Volume 37 Pages 11-21
    Published: 2019
    Released on J-STAGE: November 08, 2019

    The purpose of this study was to examine the physiological responses to intensive snow shoveling. The subjects were six males (25-71, 50±8 years) who participated in a snow removal volunteer tour. Prior to the tour, each subject engaged in a cycle ergometer test (Test 1) and a multistage shoveling test (Test 2) to evaluate the relationship between volume of oxygen consumption (VO2) and heart rate. Field measurements were performed in Miruto of Iwamizawa City, Hokkaido, Japan on February 2, 2014. Average air temperatures of that day were -6.3°C in the morning and -1.4°C in the afternoon. The snow layer at the work site had various grain shapes and snow density linearly increased with snow depth. While snow hardness increased exponentially with increase in snow depth. Mean heart rate during working time in the afternoon (142±9 beats min-1) was significantly (p<0.01) higher than that in the morning (131±9 beats min-1). These heart rates correspond 84% and 77% of the predicted maximum heart rate (HRmax), respectively. Ratings of perceived exertion were not different in the morning (12.9±0.4) and afternoon (12.4±0.3). The mean values of VO2 in the total work period (111±3 min) was estimated to be 22.2±1.2ml kg-1min-1 (Metabolic equivalent; 6.4±0.3METs). Estimated energy expenditure averaged 782±46kcal. It is conceivable that increase in snow hardness and snow density caused an increase in work intensity.

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  • Oanh PHAM Kim, Kazushi NORO, Yoshie NABESHIMA, Tatsuya TANIGUCHI, Yusu ...
    2019 Volume 37 Pages 23-30
    Published: 2019
    Released on J-STAGE: December 21, 2019

    The polycyclic aromatic hydrocarbons (PAHs) in snow were measured in eastern Dronning Maud Land, East Antarctica. The sources of these PAHs were the snow mobiles and diesel electric generators used for scientific research from 29th December 2015 to 4th February 2016. Most of the measured PAH concentrations were low before the research campaign (lower than the detection limit or quantification limit), then increased due to the research activities, and finally decreased to a low level (lower than the quantification limit), probably because of strong blizzard winds. In addition, photolysis of the PAHs in the polluted snow samples under Antarctic conditions was investigated. The snow samples polluted by diesel electric generators were collected before and after irradiation under Antarctic sunlight (11 days); however, a decrease in PAH concentration was not observed. It was concluded that photolysis was not the main sink of the PAHs in Antarctic snow, but the occurrence of blizzard/drifting snow decreased the PAH concentration. In this paper, the preservation method for the snow samples to measure the PAHs correctly was also evaluated. To stabilize the PAHs in snow, hexane had to be added to the snow sample. Even if the snow sample was kept in a freezer, PAHs evaporated without hexane.

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  • Wataru SHIGEYAMA, Naoko NAGATSUKA, Tomoyuki HOMMA, Morimasa TAKATA, Ku ...
    2019 Volume 37 Pages 31-45
    Published: 2019
    Released on J-STAGE: December 17, 2019

    Mass loss from ice sheets contributes to global sea level rise, and accelerated ice flow to the oceans is one of the major causes of rapid ice sheet mass loss. To understand flow dynamics of polar ice sheets, we need to understand deformation mechanisms of the polycrystalline ice in ice sheets. Laboratory experiments have shown that deformation of polycrystalline ice occurs largely by dislocation glide, which mainly depends on crystal orientation distribution. Grain size and impurities are also important factors that determine ice deformation mechanisms. Compared with ice formed during interglacial periods, ice formed during glacial periods, especially ice that forms cloudy bands, exhibits finer grain sizes and higher impurity concentrations. A previous report suggests the deformation rate of ice containing cloudy bands is higher than that of ice without cloudy bands. To examine the microstructures and deformation histories of ice in cloudy bands, we applied the electron backscatter diffraction (EBSD) technique to samples from the Greenland Ice Sheet using an environmental scanning electron microscope (ESEM) equipped with cold stages. Prior to the EBSD analysis, we optimised our ESEM/EBSD system and performed angular error assessment using artificial ice. In terms of c- and a-axis orientation distributions and grain orientation spread, we found little difference between samples taken from a cloudy band and those taken from an adjacent layer of clear ice. However, subgrain boundary density and orientation gradients were higher in the cloudy band, suggesting that there are more dislocations in the cloudy band than in the clear ice layer.

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  • Masahiro MINOWA, Marius SCHAEFER, Pedro SKVARCA, Sumito MATOBA, Guisel ...
    2019 Volume 37 Pages 47-56
    Published: 2019
    Released on J-STAGE: February 14, 2020

    To better understand the temporal variation of the ice surface elevation and the spatio-temporal variation of snow accumulation in the accumulation area of the Southern Patagonian Icefield, we carried out a glaciological traverse in October 2018. This included measurements of surface elevation, firn layers, and sampling of snow in the accumulation areas of Glaciar Viedma and Glaciar Pío XI. The main results from the traverse are: i) during the period of 2000-2018 the surface elevation in the accumulation area of Glaciar Viedma decreased by 1.7ma-1, but increased at Glaciar Pío XI by 0.4ma-1, ii) ground-penetrating radar revealed numerous firn layers with a continuous water aquifer at 20-40m depth, iii) the water isotope ratio of surface snow samples varied with wind direction. Repeating the traverse in the area will provide an opportunity to answer questions about the contrasting glacier behavior and the snow accumulation rate, a necessary step to make reliable projections of future glacier behavior in Patagonia.

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