Antarctica

摘要： The Regional Ocean Modeling System(ROMS)is employed to create a three-dimensional numerical model of the summer circulation in the Prydz Bay region,Antarctica.Consistent with the currents measured using an underway acoustic Doppler current profiler during a Chinese cruise,the simulated current field illustrates the major features of the Prydz Bay circulation,including the Antarctic Slope Current(ASC)along the continental shelf break,the cyclonic Prydz Bay Gyre,and the Prydz Bay Eastern Coastal Current(PBECC).The effects of grounding icebergs D15 and B15 on the circulation in Prydz Bay are investigated via numerical simulations.The results indicate that these giant grounding icebergs substantially affect the flows into and within the bay,which may differ with the different grounding locations.As grounding iceberg D15 is located close to the southwestern part of the West Ice Shelf(WIS),it cuts off the coastal current along the outer edge of the WIS,and the ASC can only enter Prydz Bay from the west side of iceberg D15,whereupon it becomes a main source of the PBECC.Iceberg D15 also weakens the circulation in the bay in general.The relatively small iceberg B15 entered Prydz Bay from 2007 to 2009 and grounded on the southwestern section of the Four Ladies Bank.The numerical experiments indicate that iceberg B15 guides the ASC flowing into the bay around its west side and reduces the width of the inflow on the eastern side of the Prydz Bay Channel.The grounding of iceberg B15 has also led to adjustments of the circulation within the bay,among which the most significant is that the outflow along the western flank of Fram Bank has shifted to the west and become more intensive.

摘要： Ice cores have revolutionized our views of the Earth system.They record past climatic and environmental parameters that range on time scales from synoptic events to hundreds of thousands of years.For instance,the Vostok ice core reached an age of 420 ka(thousand years)(Figure 1),revealing a close linkage between climate and greenhouse gas concentrations over the last four glacial-interglacial cycles(Petit et al.,1999).

摘要： Several studies have documented that plastic pollution is affecting one of the most remote and pristine regions of our planet,Antarctica.Plastics of different size and polymeric composition have been retrieved in Antarctic sea ice,surface waters and sediments,with microplastics(mostly fibers)found both in terrestrial and marine organisms.Such evidence raises concerns about potential detrimental effects on biodiversity and ecosystem functions.The present review aims to report the most up-to-date knowledge on occurrence and distribution of plastic pollution in the Antarctic environment and biota including interaction with microorganisms,potential sources,and its impact on Antarctic biota.Our understanding of plastic pollution in this polar region will help us define the human footprint in Antarctica and predict future ecological risks.

摘要： We here report the de novo transcriptome assembly and functional annotation of Eusirus cf.giganteus clade g3,providing the first database of expressed sequences from this giant Antarctic amphipod.RNA-sequencing,carried out on the whole body of a single juvenile individual likely undergoing molting,revealed the dominant expression of hemocyanins.The mRNAs encoding these oxygen-binding proteins cumulatively accounted for about 40%of the total transcriptional effort,highlighting the key biological importance of high hemocyanin production in this Antarctic amphipod species.We speculate that this observation may mirror a strategy previously described in Antarctic cephalopods,which compensates for the decreased ability to release oxygen to peripheral tissues at sub-zero temperatures by massively increasing total blood hemocyanin content compared with temperate species.These preliminary results will undoubtedly require confirmation through proteomic and biochemical analyses aimed at characterizing the oxygen-binding properties of E.cf.giganteus clade g3 hemocyanins and at investigating whether other Antarctic arthropod species exploit similar adaptations to cope with the challenges posed by the extreme conditions of the polar environment.

摘要： Scientists recently reported an unusual finding:the discovery of the second-largest egg known to exist.The egg,a 68 million-year-old fossil,was found on Seymour Island,off the coast of Antarctica.The fossil is said to be about the size of a football—without the air inside.It measures around 29 centimeters by 20 centimeters.

摘要： Over the past 25 years,I have taken photographs in dozens of continents—from Antarctica to Iceland and the Pacific Northwest.And now,I want to share something about my journey to Antarctica with you.For me,the highlights of this trip are the endless variety and beautiful forms of the polar ice,the stunning mountain scenery and walking among penguin colonies.Antarctica is an unparalleled destination for photography because there are dramatic scenes constantly in front of you.Craggy black mountains stick out everywhere along the coast,many with cloud caps hovering over them.Penguin colonies dot the landscape,and the soundtrack is the soft but frequent call of penguins.

摘要： The background surface O3 concentrations and seasonal changes observed at the Zhongshan Station (69°22'2''S, 76°21'49''E;18.5 m), east Antarctica from 2008 to 2013 are presented. Irrespective of wind direction, surface O3 concentrations distribute evenly after the removal of polluted air from station operations, accounting for 1.1% of the data. These O3 exhibit the expected lowest in summer, with a peak in winter. The daily range of average O3 in all four seasons is small. The monthly mean O3 is similar to that of other stations in Antarctica, with seasonal CO2 amplitudes in the order of 15 ppb to 35 ppb. Surface O3 significantly negatively correlated with UVB in the spring and autumn, with correlation coefficients of 0.50 and 0.57 under the 0.01 significance test. Furthermore, the surface O3 concentration during polar nights was 1 - 2 times higher than that during polar days. Thus, the chemical effect of the aurora lights was the dominant cause of ozone destruction, showing that surface O3 observed in Antarctica has a small interferences from human activities in the atmosphere as it moves from the north through the southern hemisphere.

摘要： During the period from October 2014 to March 2015, a total number of 82 seismic tremors and 66 ice-quakes were identified in both three-component short-period seismographs (HES) and broadband seismographs (STS-1) at Syowa Station (SYO), Antarctica. Statistics of the number of these tremors indicated that many tremors were likely to occur when large increases in temperature and/or wind speed during the period. This implied that the rapid increase in temperature enhanced a melting speed of cryosphere environment with generating seismic energy;the tremors were also excited by stormy conditions, associated with interactive resonance between sea-ices and oceanic swells. The characteristic tremors of harmonic overtones with strong amplitudes were explained by repetitive sources, suggesting inter-glacial asperities such as the collision of icebergs and fast sea-ice, calving of glaciers/ice-streams at the coastal environment of Antarctica. These high amplitude tremors occurred independently from other majority types of events, characterized by non-linear, small amplitude and weak signals at the stormy condition and rapid increase in temperature.

摘要： Characteristics and statistics of seismic tremors occurring during April 2015 were investigated by using short-period and broadband seismographs deployed at Syowa Station (SYO), in the Lützow-Holm Bay (LHB), East Antarctica. In order to examine a relationship between surface environments in particular cryosphere variation, the MODIS satellite images were utilized for comparison with the detected tremor events. Since a large volume of sea-ice was discharged during the April, together with several large icebergs passed through from the west to the east at northern edge of the fast sea-ice of LHB, it was expected to detect seismic tremors involving cryospehre dynamics. During the month, a total number of 49 tremor events including short duration ice shocks were identified. Majority of the events (N = 39) had their duration times more than 15 minutes, which were divided into both tremors and ice shocks on the basis of experienced definition at SYO. Cryospheric sources recorded by seismic tremors were classified into several origins (collision, calving, crevassing, crashing, etc.): “crevassing events” along the large cracks inside the fast sea-ice in LHB (04 April), “discharge events” of fast sea-ice from the Bay (07 April), “collision events” between iceberg and the edge of fast sea-ice (14 April), “crashing movement” between fragmentation of fast sea-ice and packed sea-ice (18 April), and other origins. In particular, strong amplitude tremors with harmonic overtones were assumed to be occurred independently from whether condition, because these overtone tremors were identified at less stormy days by comparison with infrasound data at SYO.