极地研究

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Sapphirine in the high-grade quartzofeldspathic gneiss of the Larsemann Hills, East Antarctica

Ren Liudong, Wang Yanbin, Zhao Yue

2008, 19 (1-English): 1-13.

摘要 ( 1168 )

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Study of sapphirine and related mineral association in the high-grade re- gion of the Larsemann Hills, East Antarctica,shows that sapphirine of the area is characterized by its magnesio-, iron-and aluminum-rich, but silica-poor feature,and the obvious intra-and intergrain changes in compositions. The change is mainly mani- fested as the Tschermark substitution (Mg, Fe)+Si=2Al. In the high-grade meta- morphism and anatexis process the multistage crystallization of minerals occurred and resulted in the complexity of the mineral association, such as the differentiation of leuco-and melano-components. Among them, the mafic-rich minerals formed earlier, and the differentiation of magnesio-and iron-components is responsible for the earlier presence of iron-rich minerals and later crystallization of magnesio-rich minerals, thus the successive associations of multistage occurred. The rock composition is an impor- tant but not critical factor to the occurrence of sapphirine. It is the mobilization of components that accounts for the formation of sapphirine. The multistage evolution of mineral association to some degree reflects the changing composition and opening of the setting. It is therefore deduced that the protolith from which sapphirine is derived is not necessarily magnesio-rich polite. The heterogeneity of sappbirinc composition is resulted from the various media,not the PT changes.Sapphirine formed at 840～880℃, not the so-called ultrahigh temperature condition (>1000℃). Its for- mation is related to both the filtration and diffusion processes in high-grade metamor- phism and anatexis.

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Distribution of general aerobic heterotrophic bacteria in sediment core taken from the Canadian basin and the Chukchi Sea

Gao Aiguo, Chen Haowen

2008, 19 (1-English): 14-22.

摘要 ( 1217 )

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The occurrence percentage and abundance of General Aerobic Hetero-trophic Bacteria (GAB) were determined by using the method of MPN for 182 sub-samples from 10 sediment cores taken from the Canadian basin and the Chukchi Sea at two different culturing temperatures. The results showed that the general occurrence percentage of CAB was quite high, average abundances of GAB at cultured temperatures of 4℃and 25℃were 4.46×10⁷ and 5.47×10⁷ cells·g^-1(wt), respectively. The highest abundance of GAB occurred at 20～22 cm section in the sediment. CAB abundances changed among the section of sediments, but there is a trend:the abundances at the middle or lower sections were lower than those at upper section. Cultivation at 25℃could improve the occurrence percentage and abundances of GAB,which suggests that the increasing of temperature may change the living circumstances of GAB. The differences of GAB among the latitudes areas indicated that occurrence percentage and abundances of GAB in middle latitude areas were higher than those in the higher or lower latitude areas,and were more obvious at 4℃than those at 25℃. The GAB abundances in sediment under the shallower water seemed to be lower than those in sediments under the deeper water and this status was more obvious at 25℃than that at 4℃.

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GLIMMER Antarctic Ice Sheet Model, an experimental research of moving boundary condition

Tang Xueyuan, Sun Bo, Zhang Zhanhai, Li Yuansheng, Yang Qinghua

2008, 19 (1-English): 23-35.

摘要 ( 1082 )

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A 3-D coupled ice sheet model, GLIMMER model is introduced,and an idealized ice sheet experiment under the EISMINT-1 criterion of moving boundary condition is presented. The results of the experiment reveal that for a steady-state ice sheet profile the characteristic curves describe the process of evolution which are accordant with theoretical estimates. By solving the coupled thermodynamics equations of ice sheet, one may find the characteristic curves which derived from the conservation of the mass, energy and momentum to the ice flow profile. At the same time,an agreement, approximate to the GLIMMER case and the confirmed theoretical results, is found. Present study is explorihg work to introduce and discuss the handicaps of EISMINT criterion and GLIMMER,and prospect a few directions of the GLIMMER model.

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The identification and comparison of the bio-elements of the penguin ornithogenic sediments sample from Davis Station and Great Wall Station

Huang Tao, Sun Liguang, Wang Yuhong, Zhu Renbin

2008, 19 (1-English): 36-44.

摘要 ( 973 )

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During CHINARE-22 in austral summer of 2005-2006, a lake sediment core named DG4, which is impacted by penguin droppings, was retrieved from a lake catchment in Gardner Island of Vesffold Hills, East Antarctica.In this study, the concentrations of characteristic elements in the core, local bedrocks and fresh penguin guanos were determined. P, Se, F, S, As, Sr and Cu in DG4 were identified as the bio-element assemblage by R-clustering analysis and compared with those in the local bedrocks and fresh guanos, the results are similar to Y2 in Ardley Island, Antarctic Peninsula. On this basis, P and Se were identified as the optimum bio-elements in DG4 and F, P and S were identified in Y2, respectively. This work will provides the foundation for reconstructing the past penguin populations in Gardner Island of Vest- fold Hills, East Antarctica and comparing the penguin population dynamics between East Antarctica and Antarctic Peninsula.

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Biogenic silica in surficial sediments of Prydz Bay, Antarctica

Hu Chuanyu, Xue Bin, Yu Peisong, Pan Jianming

2008, 19 (1-English): 45-53.

摘要 ( 1361 )

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The content and distribution of biogenic silica were investigated in sediment cores from Prydz Bay, Antarctica, during the CHINARE-18/21 cruise. The results show that the content of biogenic silica (BSiO₂) is ranged from 4.89% to 85. 41%, and the average content of biogenic silica is 30.90%, the highest value occurred at the Ⅳ-10 station. The profile of BSiO₂ in sediment is contrast to that of silicate in the interstitial water. The content of biogenic silica and organic carbon in the surface sediments in the central area of Prydz Bay gyre were much higher than those in other area,and closely related to the Chla content and primary productivity of phytoplankton in the surface water column.

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Summer fast ice evolution off Zhongshan Station,Antarctica

Lei Ruibo, Li Zhijun, Zhang Zhanhai, Cheng Yanfeng, Dou Yinke

2008, 19 (1-English): 54-62.

摘要 ( 1015 )

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Based on the field data acquired in the program of fast ice observation off Zhongshan Station, Prydz Bay, East Antarctica during the austral summer 2005/ 2006,physical properties evolution of fast ice during the ice ablation season is analyzed in detail. Results show that the annual maximum ice thickness in 2005 occurred in later November,and then ice started to melt, and the ablation duration was 62 days; sea water under the ice became warmer synchronously; corresponding to the warming sea ice temperature, a "relative cold mid-layer" appeared in sea ice; the fast ice marginal line recoiled back to the shore observably, and the recoil distance was 20.9 km from 18 December 2005 through 14 January 2006. In addition, based on the data of sea ice thickness survey along the investigation course of MV Xuelong on December 18 of 2005, the ice thickness distribution paten in the marginal ice zone have been described: sea ice thickness increased, but the diversity of floe ice thickness decreased from open water to fast ice zone distinctly.

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Plant Community and Nutrient Status of the Soils of Schirmacher Oasis, East Antarctica

Shiv Mohan Singh, Jagdev Sharma, Rasik Ravindra, Purnima Singh

2008, 19 (1-English): 63-76.

摘要 ( 950 )

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Investigations on plant community and micronutrient status of Schirmacher Oasis,East Antarctica have been presented in this paper.The dominant plant com- munities include moss and lichen.The frequency of species occurrence and changes in species composition at different location varied.Thirty-four soil samples were ana- lyzed for chemical properties of the soils of Schirmacher Oasis and Nunatak,East Ant- arctica.The most common plant species growing throughout the areas of Schirmacher Oasis and Nunataks are:Candelariella flava (lichen) and Bryum pseudotriquetrum (moss).Large variations were observed among different soil samples in all the nutri- ents and other measured soil chemical parameters.The soils are characterized by a- cidic pH ranging from 4.42-6.80.The mean organic carbon content was 0.62 and ranged from 0.06-1.29%.The electrical conductivity in 1:2 soil water ratio ranged from 0.06-1.29.The average content of macronutrient cation,which are ammonium acetate extractable was in the order of Ca>K>Na>Mg.The average content of DTPA extractable micronutrient cations was in the order of Fe>Mn>Cu>Zn.Thirty one out of 34 samples contained less than 0.80 ppm DTPA extractable Zn. Correlation studies revealed that content of macronutrient cations significantly and positively correlated to that of chlorides.Electrical conductivity exhibited significant and positive relationship with pH,K,Ca,Mg,Na and chloride content.Sodium (r =0.876~(**)) exhibited highest correlation followed by K (r=0.831~(**)) with chlo- ride content.The correlation coefficient for chlorides was higher with electrical con- ductivity (r=0.732~(**)) than pH (r=0.513~(**)).Organic carbon content of the soil was positively correlated with Fe (r=0.442~*).The nutrient status did not ap- pear to be a limiting factor in growth of plants.Lichen and moss community structure and composition in the study area were not related with fertility status of soil.Terres- trial mosses are most abundant and luxuriant along the soil habitats near bank of water bodies and the melt water streams.

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Studies on culture condition and extracellular hydrolase of psychrophilic bacteria from Arctic sea ice

Li Xiaohui, Yu Yong, Li Huirong, Zhang Lin, Jiang Xinyin, Ren Daming

2008, 19 (1-English): 77-84.

摘要 ( 1121 )

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Arctic sea ice in the polar region provides a cold habitat for microbial community.Arctic sea ice microorganisms are revealed to be of considerable importance in basic research and potential in biotechnological application. This paper investigated the culture condition and extracellular hydrolase of 14 strains of different Arctic sea ice bacteria. The results showed that optimal growth temperature of strains is 15℃or 20℃. The optimal pH is about 8.0. They hardly grow at acid condition. 3% NaCl is necessary for better growth. These strains have different abilities in producing amylase, protcase, cellulase and lipase. Pseudoalteronomas sp. Bsi429 and Pseudoalteronomas sp. Bsi539 produced both cellulose, protease and lipase. These results provide a basis for further developing and exploiting the cold adapted marine enzyme resources.

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The first geodetic investigation at the summit of Dome A, Antarctica

Zhang Shengkai, E Dongchen, Li Yuansheng, Wang Zemin, Zhou Chunxia, Shen Qiang

2008, 19 (1-English): 85-92.

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Dome A is the highest ice feature in the Antarctica, up to now, little is known about surface topography at Dome A. The first Chinese ITASE expedition was carried out from Zhongshan station to Dome A during the 1996/1997 austral summer. During the 2004/2005 austral summer, the traverse was extended to the summit of Dome A which is 1228 km from Zhongshan Station by 21st Chinese National Antarctic Research Expedition (CHINARE). The real-time kinematic (RTK) GPS survey was carried out in the summit of Dome A during 2004/05 austral summer.The surface topography of Dome A was drawn up using the kinematic double-frequency GPS data covering an area of about 70 km². The accuracy of the kinematic survey is in the range of 0.20 m. Precise surface topography, bedrock morphology and internal laye- ring geometry are important for the future selection of the best site for deep drilling at Dome A.

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