Abstract (
)
Download PDF (
)
Knowledge map
Save
Three ship-based observational campaigns were conducted to survey sea ice and snow in Prydz Bay and the surrounding waters (64.40°S-69.40°S,76.11°E-81.29°E) from 28 November 2012 to 3 February 2013.In this paper,we present the sea ice extent and its variation,and the ice and snow thickness distributions and their variations with time in the observed zone. In the pack ice zone,the southern edge of the pack ice changed little,whereas the northern edge retreated significantly during the two earlier observation periods.Compared with the pack ice,the fast ice exhibited a significantly slower variation in extent with its northernmost edge retreating southwards by 6.7 km at a rate of 0.37 km?d-1.Generally,ice showed an increment in thickness with increasing latitude from the end of November to the middle of December.Ice and snow thickness followed an approximate normal distribution during the two earlier observations (79.7±28.9 cm,79.1±19.1 cm for ice thickness,and 11.6±6.1 cm,9.6±3.4 cm for snow thickness,respectively),and the distribution tended to be more concentrated in mid-December than in late November. The expected value of ice thickness decreased by 0.6 cm,whereas that of snow thickness decreased by 2 cm from 28 November to 18 December 2012.Ice thickness distribution showed no obvious regularity between 31 January and 3 February,2013.
Abstract (
)
Download PDF (
)
Knowledge map
Save
The thermodynamic properties of snow cover on sea ice play a key role in the ice-ocean-atmosphere system and have been a focus of recent scientific research.In this study,we investigated the thermodynamic properties of snow cover on sea ice in the Nella Fjord,Prydz Bay,East Antarctica (69°20′S,76°07′E),near the Chinese Antarctic Zhongshan Station.Our observations were carried out during the 29th Chinese National Antarctic Research Expedition.We found that the vertical temperature profile of snow cover changed considerably in response to changes in air temperature and solar radiation during the summer.Associated with the changes in the temperature profile were fluctuations in the temperature gradient within the upper 10 cm of the snow cover.Results of previous research have shown that the thermal conductivity of snow is strongly correlated with snow density. To calculate the thermal conductivity in this study,we measured densities in three snow pits.The calculated thermal conductivity ranged from 0.258-0.569 W·m-1?K-1.We present these datasets to show how involved parameters changed,and to contribute to a better understanding of melting processes in the snow cover on sea ice.
Abstract (
)
Download PDF (
)
Knowledge map
Save
MIL090036 is a previously unknown meteorite (a feldspathic lunar breccia) that was discovered in Antarctica. The detailed petrography and mineralogy of this meteorite forms the subject of this paper. It has a typical clastic texture that consists of various types of rock debris (e.g. anorthosite, gabbroic anorthosite, gabbro, regolith breccia, troctolite, microporphyritic crystalline impact melt and compound clasts), mineral crystal fragments (e.g. pyroxenes, plagioclase, olivine and ilmenite) and feldspathic glass clasts. The fine-grained recrystallized minerals and mineral clasts are cemented together in a glassy groundmass. The anorthite content of plagioclase in the gabbro (An81-83) and anorthosite (An88-93) both have relatively low calcium content compared to those from other breccias (An90-98). The pyroxene composition (Fs12-35 Wo3-44 En22-79) in the rock debris, crystal mineral clasts and anorthositic glass clasts are relatively iron-deficient compared to those from gabbro debris with melt glass (Fs37-65 Wo10- 29 En21-49) and groundmass (Fs18-69 Wo3-45 En14-50). In contrast, the pyroxene grains in the gabbroic anorthosite display a narrow compositional range (Fs24-27 Wo7-14 En59-69). Olivine grains in mineral fragments and the groundmass have a wider compositional range (Fo57-79) than those in the rock debris (Fo67-77). The Fe/Mn ratio in olivine is in the range of 47 to 83 (average 76) and 76 to 112 (average 73) in pyroxenes, and hence classify within the lunar field. The characteristics of texture, mineral assemblage and compositions suggest that MIL090036 possibly originated from a region beyond that of the Apollo and Luna samples. Further study of MIL090036 is therefore likely to lead to a better understanding of the geological processes on the Moon and the chemical composition of the lunar crust.
Abstract (
)
Download PDF (
)
Knowledge map
Save
The Grove Mountains, located between the Zhongshan Station and Dome A, are a very important area in inland Antarctic research. China has organized five investigations of the Grove Mountains, encompassing the geological structure, ancient climate, meteorites, ice-movement monitoring, basic mapping, meteorological observations, and other multi-disciplinary observational studies. During the 26th Chinese National Antarctic Research Expedition in 2010, the Grove Mountains investigation team applied specialized ground-penetrating radar (GPR) to survey subglacial topography in the eastern kernel area of the Grove Mountains. In this paper, we processed GPS and GPR data gathered in the field and drew, for the first time, two subglacial topographic maps of the Grove Mountains kernel area using professional graphics software. The preliminary results reveal the mystery of the nunatak landform of this area, give an exploratory sense of the real bedrock landforms, and indicate a possible sedimentary basin under the Pliocene epoch fossil ice in the Grove Mountains area. Additionally, it has been proven from cross-sectional analysis between Mount Harding and the Zakharoff ridge that the box-valley shape between two nunataks has already matured.
Abstract (
)
Download PDF (
)
Knowledge map
Save
There are a number of ionospheric models available for research and application, such as the polynomial model, generalized trigonometric series function model, low degree spherical harmonic function model, adjusted spherical harmonic function model, and spherical cap harmonic function analysis. Using observations from more than 40 continuously operating stations across Antarctica in 2010, five models are compared with regard to their precision and applicability to polar regions. The results show that all the models perform well in Antarctica with 0.1 TECU of residual mean value and 2 TECU of root mean square error.
Abstract (
)
Download PDF (
)
Knowledge map
Save
Antarctic krill is a potentially nutritious food source for humans, but fluorine (F) toxicity is a matter of concern. To evaluate the toxicity of F in Antarctic krill, 30 Wistar rats were divided into three groups with different dietary regimens: a control group, a krill treatment group (150 mg·kg-1 F), and a sodium fluoride (NaF) treatment group (150 mg·kg-1 F). After three months, F concentrations in feces, plasma, and bone were determined, and the degree of dental and skeletal fluorosis was assessed. The F concentrations in plasma and bone from the krill treatment group were 0.167 0±0.020 4 mg.L-1 and 2 709.8±301.9 mg·kg-1, respectively, compared with 0.043 8±0.005 5 mg·L-1 and 442.4±60.7 mg·kg-1, respectively, in samples from the control group. Concentrations of F in plasma and bone in the krill treatment group were higher than in the control group, but lower than in the NaF treatment group. The degree of dental fluorosis in the krill treatment group was moderate, compared with severe in the NaF treatment group and normal in the control group. The degree of skeletal fluorosis did not change significantly in any group. These results showed that the toxicity of F in Antarctic krill was lower than for an equivalent concentration of F in NaF, but it was toxic for rats consuming krill in large quantities. To conclude, we discuss possible reasons for the reduced toxicity of F in Antarctic krill. The present study provides a direct toxicological reference for the consideration of Antarctic krill for human consumption.
Abstract (
)
Download PDF (
)
Knowledge map
Save
Bacterial diversity in surface sediment from the Arctic Ocean was investigated by culture-dependent and -independent
approaches. Conventional culture-dependent techniques revealed 11 strains based on their distinct morphological characteristics
on marine Zobell 2216E agar plates. Phylogenetic analysis showed that these isolates belonged to three major lineages of the
Bacteria,
Abstract (
)
Download PDF (
)
Knowledge map
Save
Fluorescence in-situ hybridization (FISH) and 16S rRNA gene clone library analyses were used to determine the abundance and diversity of archaea in Prydz Bay, Antarctica. Correlation analysis was also performed to assess links between physicochemical parameters and archaeal abundance and diversity within the sea-ice. Samples of sea-ice and seawater were collected during the 26th Chinese National Antarctic Research Expedition. The results of FISH showed that archaea were relatively abundant within the top layer of the sea-ice, and correlation analysis suggested that the concentration of NH4+ might be one of the main factors underlying this distribution pattern. However, using 16S rRNA gene libraries, archaea were not detected in the top and middle layers of the sea-ice. All archaeal clones obtained from the bottom layer of the sea-ice were grouped into the Marine Group I
沪公网安备 31011502017260号