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The Arctic, Antarctic and Tibetan Plateau are very sensitive to global climate change. Hence, it is urgent that we improve our understanding of how they respond to climate change, and how those responses in turn affect both regional and global climate. Against a background of current global warming, the three poles display climate diversities temporarily and spatially, which to different degrees affect the weather and climate over China. Enhanced monitoring of climate change in these three areas, as well as connected work on the responses and feedbacks of the three regions to climate change, will provide necessary support for adaptation and the sustainable development of the Chinese economy.
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Conductivity, temperature and depth(CTD) data collected along a zonal hydrographic section from the northern margin of the Amery Ice Shelf on 25-27 February 2008 by the 24th Chinese National Antarctic Research Expedition (CHINARE) cruise in the 2007/2008 austral summer are analyzed to study thermohaline structures. Analysis reveals warm subsurface water in a limited area around the east end of the northern margin, where the temperature, salinity and density have east-west gradients in the surface layer of the hydrographic section. The localization of the warm subsurface water and the causes of the CTD gradients in the surface layer are discussed. In addition, the results from these CTD data analyses are compared with those from the 22nd CHINARE cruise in the 2005/2006 austral summer. This comparison revealed that the thermoclines and haloclines had deepened and their strengths weakened in the 2007/2008 austral summer. The difference between the two data sets and the cause for it can be reasonably explained and attributed to the change in ocean-ice-atmosphere interactions at the northern margin of the Amery Ice Shelf.
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The shock metamorphism of 47 H group chondrites (H-chondrites) from the Grove Mountains including undulatory extinction, planar fractures, mosaic extinction, shock veins and pockets, and dendritic eutectic metal-sulfide, is observed through optical microscope. The textures and assemblages of shock veins in these H-chondrites are examined by the scanning electron microscope. Based on observations of the above shock effects, the shock stages of the 47 H-chondrites are classified into S1(5), S2(19), S3(14), S4(8) and S5(1). Of these H-chondrites, GRV 022469 has the highest(S5) shock stage. The comparison of shock stages in these H-chondrites with L group chondrites(L-chondrites) indicates that the shock metamorphism of H-chondrites is relatively low (except for GRV 022469, they are all lower than S5). A scenario for the history of the H-chondrite parent body is proposed that suggests the duration of the shock events in the H-chondrite parent bodies was much shorter than those in L-chondrite parent bodies. Also, the pressure may have been released more quickly, and consequently, the high-pressure phases should be easily preserved. However, the parent bodies of the H-chondrites may have been exposed to high temperatures for a longer time after the shock event, so the high-pressure phases formed by solid transformation might have retro-metamorphosed to low-pressure ones; its peak pressure is estimated to be less than 15 GPa. Wadsleyite was found in a shock vein in GRV022469, as confirmed by the Raman spectrometer. Petrological and mineralogical characteristics support the idea that the wadsleyite was formed by solid-state transformation.
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Phosphatase plays an important role in the microbial liberation of phosphorus in soil systems. In this study, alkaline phosphatase activity (APA) was investigated from tundra ornithogenic soil profiles in Antarctica and Arctic. The organic carbon (TOC), total nitrogen (TN), and phosphorus fractions and pH were also analyzed in these soils. The correlation between APA and soil chemical properties is discussed. In almost all the soil profiles, APA showed the same variation patterns. The maximum APA appeared in the surface layers, and decreased with soil depth. The APA ranged from 1.00 ppm to 1 403.5 ppm with an average of approximately 408.3 ppm. The APA showed a significant positive correlation with TOC (
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Observation data recorded by the European Incoherent Scatter Scientific Association in Tromso Norway in August 2009 were analyzed to determine the heating effects in polar summer ionospheric modification experiments. There are two types of increases in electron temperature: large relative increases in a narrow range near 150 km and greater absolute increases in a wider range at 150-400 km. The percentage increase in temperature linearly increases with heating power, but the rate of increase decreases with increasing pump frequency. A clear two-dimensional distribution was found for the measurement made on August 15, and the heating effects are greater closer to the direction of the geomagnetic field. The heating effects obviously depend on the angle between the heating beam and geomagnetic field; as the angle increases, the heating effect decreases.
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The harsh natural and social environments in Antarctica challenge the limit of physical and psychological adaptation. Psychological research on Antarctic expeditioners’ winter-over life can enhance our understanding of how humans adapt to isolated, confined and extreme environments. In this qualitative study, nine people who worked at either the Great Wall station or Zhongshan Station were interviewed. Most of the problems related to adaptation in Antarctica could be summarized and categorized into four types: physical, emotional, interpersonal and task-related. Two main sets of factors which impact quality of work and life in Antarctica were identified. The first set refers to internal factors comprising personality, attitude, age and previous experience. The second set is external factors including natural environments as well as conditions of stations and key persons, especially the chef and station master. A theoretical framework of coping strategies including organizational and individual aspects was developed. Among the seven ways of coping, energy transferring such as taking part in sports entertainment or learning played the most important role. The results not only provide a strong theoretical base for future research of polar psychology, but also provide an empirical base for more applications on Antarctic expeditions, flight and space missions.
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Organic geochemical analysis was performed on a sediment core HN1 from Fildes Peninsula on King George Island,
Western Antarctica. Short-chain
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The psychrotropic bacterium, Pseudoalteromonas sp. QI-1, which produces extracellular cold-active protease, was
isolated from Antarctic seawater. The genomic DNA of this bacterium was used to construct a plasmid genomic library with the
goal of screening cold-active protease genes. Gene pro-2127 with an open reading frame of 2127 bp encoding protease
PRO-2127 was cloned and sequenced. Alignment of amino acid sequences suggested that the precursor of PRO-2127 was a
member of subfamily S8A, and that it might contain four domains: a signal peptide, an N-terminal prosequence, a catalytic
domain and a C-terminal extension. Amino acids Asp185, His244 and Ser425 might form a catalytic triad. PRO-2127 showed
some structural features common to psychrophilic enzymes, such as a decrease in Arg residues and the Arg/(Arg+Lys) ratio.
Heterologous expression of pro-2127 in
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