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    30 March 2000, Volume 12 Issue 1 Previous Issue    Next Issue

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    EXTENSION AND THEORETICAL IMPROVEMENT OF A HYPOTHESIS FOR MSA MIGRATION IN ICE CORES
    2000, 12 (1):  1-9. 
    Abstract ( 1391 )   PDF (428KB) ( 1248 )  

    The most representative MSA profiles of snow/ice in the sense of migration were exhibited. The principle on which the hypothesis of MSA migration was drawn out was examined. The update data show that the mechanism responsible for MSA migration and relocation supposed for the deeper part of the ice cores could also work for the firn and infiltration congelation ice on the glacier surface. The extension given to the hypothesis by new evidences is that the migration of MSA in the firn is carried out in the open environment where air is connecting with the atmosphere. MSA in resolute is moving downwards, among grains, till the depth where cations are highly concentrated and salts could be formed via combination. It is, quite possibly, the relatively higher freezing point of newly formed methanesulphate salts (e.g. of Na + or of Mg 2+ ) that makes MSA “refrozen” and relocated. The mechanism for the migration of MSA in the infiltration congelation ice is, perhaps, the same for the deeper part of the glacier ice. The comparison of time spent on MSA migration in deeper glacier ice of Antarctic Peninsula and that in the surface infiltration congelation ice of mid latitude glacier suggests that the quick formation of interlinked network of veins in ice, higher temperature and more water content of the ice probably may sever as the promoting factors for the MSA migration. Finally the related calculation referring to the MSA migration, the experiments to verify the hypothesis in lab and problems in the improvements of the migration theory were discussed.

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    DETERMINATION OF ANTARCTIC GEOID BY USING GLOBAL GRAVITY FIELD
    2000, 12 (1):  10-17. 
    Abstract ( 1266 )   PDF (545KB) ( 1438 )  

    With Chinese latest global gravity field model WDM94, the author provides the geoid height and mean free air gravity anomaly of Antarctic(The range of latitude is from -60° to -90°). In order to conclude and analyze the characters of Antarctic geoid roundly, the author collects overseas latest global gravity field model OSU91 (to degree and order 360) and JGMOSU (to degree and order 360), gets the corresponding geoid height and mean free air gravity anomaly. The result is compared with the result got from WDM94, thus we get the difference. The standard deviation of geoid height between WDM94 and OSU91 is ±1.90m;the deviation of geoid between WDM94 and JGMOSU is ±2.09m. The standard deviation of mean gravity anomaly are ±8.97mgal and ±9.32mgal respectively.

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    CHARACTERISTIC ANALYSIS OF AURORAL ELECTROJET IN ZHONGSHAN STATION, ANTARCTIC
    2000, 12 (1):  18-23. 
    Abstract ( 1408 )   PDF (131KB) ( 1208 )  

    From the observed aurora and corresponding disturbances of geomagnetic field,we get the distribution law and its intensity of auroral electrojet near Antarctica Zhongshan Station (AZS) described by AU AL and AE indexes. We found that the intensity of east component of auroral electrojet is positive, and the west is negative. As absolute value is concerned, the west component is greater than the east. The intensity of auroral electrojet in summer is greater than that in winter around AZS. The simulation curve of the distribution law of east component in the seasons of summer autumn and winter is like a up parabola curve between 720 and 1440 min(UT 12-24 hour). And that of the west is just like a sine wave curve. The distribution characteristic of auroral electrojet in AZS, is helpful for the studies of F layer and magnetosphere coupling in polar region and aurora dynamics.

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    RADIOLARIA FOSSILS OF THE SURFACE SEDIMENTS IN THE BERING SEA AND ITS SEDIMENTARY ENVIRONMENT
    2000, 12 (1):  24-31. 
    Abstract ( 1390 )   PDF (451KB) ( 1515 )  

    Total number 2472, 36 genera and 45 species are distinguished after the radiolaria fossils from 12 surface sediments in the Bering Sea are analysed. The distribution characteristics of radiolaria fossils in the surface sediments is as follows: 1. From the shelf of shallow water to the upper area of continental slope, there are a few radiolaria fossils and monotonous genus and species. 2. In the low area of continental slope, radiolaria fossils are poor in the volcanic cinders and turbidite. 3. The abundance and diversity of radiolaria fossils are high in the clay of basin. The dominant species of radiolaria is Spongotrochus glacialis on the continental shelf. The current, topography, water depth, water temperature etc. are key factors influencing radiolaria distribution. The sources of sediments mainly are terrigenous sediments,biogenic sediments and volcanic sediments in the suvey area and they are mostly from the Kamchatka Peninsula in the east of USSR and Aleutian Islands.

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    ARCTIC EXPEDITION AND A PRELIMINARY RESEARCH OF GPS POSITIONING
    2000, 12 (1):  32-39. 
    Abstract ( 1314 )   PDF (243KB) ( 1377 )  

    This article presents the virgin scientific expedition of surveying and mapping while the author was a member of the “Arctic Tracing” expedition team. During it, following the route: Resolute-Qaanaaq-Kapyok-Eureke-North Pole-Eureke-Resolute, GPS( Global Positioning System) was employed to guide the ice ocean expedition route, search out north pole and take fixed point observations at Qaanaaq and Resolute. Whereafter, a specific software for GPS data processing was utilized to process and analyse the data collected during the expedition so that the geodetic coordinates of observed points and the cord length of spatial baselines from each observed point to Beijing were got. The results show that it is feasible in Arctic to utilize GPS to monitor crust movement and dynamic variations of environment with high accuracy within large scale range.

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    THE IMPACT OF OZONE DEPLETION AND ULTRAVIOLET RADIATION ON MARINE PHYTOPLANKTON
    2000, 12 (1):  40-61. 
    Abstract ( 1275 )   PDF (858KB) ( 1801 )  

    The ozone depletion is created by CFCs pollutants from human activities. And this causes more UV B radiation which is harmful to marine species. According to relative research and informaiton, this paper discusses the formation of “ozone hole” and the biochemical effect of UV B on marine phytoplankton, including the tolerance and resistance of marine species to UV B, the effect of UV B on biochemical environment of marine phytoplankton cells.

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    ANTHROPIC IMPACTS ON THE ANTARCTIC TERRESTRIAL ECOSYSTEM
    2000, 12 (1):  62-74. 
    Abstract ( 1577 )   PDF (438KB) ( 1583 )  

    An awareness of human impacts on the Antarctic terrestrial ecosystem has been increasing in the recent decades due especially to the expansion of scientific expeditions and the tourism industry. In this paper, localized contamination of soil and vegetation, disturbance of wildlife, import of alien organisms as well as introduction of exogenous bacterial diseases as a result of human activities undertaken in Antarctica have been outlined. Besides, potential threats to the Antarctic environment from the contaminants emanating from sources outside Antarctica have also been demonstrated. Finally, efforts and progress within the Antarctic Treaty System towards protection of the Antarctic environment and its terrestrial ecosystem are briefly summarized. [WT5BZ][WT5HZ]

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