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30 June 2012, Volume 24 Issue 2 Previous Issue    Next Issue

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The Oceanographic features near Amery Ice Shelf of the Prydz Bay in January 2011 Yan Jinhui，Li Ruixiang，Shi Maochong，Ge Renfeng，Sun Yongming 2012, 24 (2):  101-109.  DOI: 10.3724/SP.J.1084.2012.00101 Abstract ( 2990 )   PDF (4530KB) ( 1508 )   Based on the CTD observational data from 24 stations of a section over the north edge of the Amery Ice Shelf during the 27th Chinese National Antarctic Research Expedition executed by China ‘Xuelong’ vessel, some oceanographic features are described as follow: In the west of the Prydz Bay, about the range of 71-72oE, there exists a clockwise mesoscale eddy. Owing to the existence of eddy, the ice shelf water flows mainly eastward, and it flows to the northeast near 73o30' E. In summer, the thickness of the surface water in the eastern section is about 20m, influenced by the eddy that in the western section is approximately 50m. Within the water less than 50m, water temperature in deeper layer slightly greater than in surface, i.e. so called temperature inversion layer, which is caused by freezing and melting of the sea ice. In the west of the section, there appears ‘static instability’ at many stations about 160m~200m in depths, i.e. the density is greater than that in lower with several meter in thickness. Advection mixing diffusion may be the main causing factor for this instability. Related Articles | Metrics

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Comparison of surface water N2O saturation anomalies between tropical and the Antarctic waters Chen Liqi，Zhan Liyang，Xu Suqing，Zhang Jiexia，Xu Guojie 2012, 24 (2):  110-119.  DOI: 10.3724/SP.J.1084.2012.00110 Abstract ( 2757 )   PDF (2560KB) ( 1426 )   Characteristics of surface water partial pressure of N2O and their saturation anomalies were compared between the tropic waters from 30?N in the Western Pacific to 30?S in East Indian Ocean and the Antarctic waters from the Southern Ocean to Prydz Bay, East Antarctica. Several major factors were analyzed for driving differences of saturation anomalies between the tropic and the Antarctic waters. The surface water pN2O from Prydz Bay was an average of 311.9 ± 7.6 nL/L (14.1 ± 0.4 nM), less unsaturated relative to atmospheric mixing ratio (318.5 nL/L). This instauration would be attributed from melted seaice water being mixed to bring lower pN2O. Air-sea flux of N2O was about -0.3 ± 0.8 μmol m-2d-1. However, N2O saturation anomalies appeared in most tropical surface waters higher than 10% with the maximum of 54.7% found in Equatorial waters and higher of 31% around 10?N in the Sulu sea. Air-sea fluxes were calculated for the tropic waters and Sulu Sea respectively as ?12.4 μmol m-2 d-1 and ~4 μmol m-2 d-1, suggesting that low latitudinal tropical waters would play a significant role as an atmospheric N2O source. This might be caused due to weak air-sea exchange and strong upwelling. However in the high latitudinal Antarctic waters, stratification by melted seaice waters would prevent from upwelling in the Prydz Bay and persistent strong westerly would enhance air-sea exchange rate, especially surface wind would be an important factor to impact air-sea flux of N2O. References | Related Articles | Metrics

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Summertime fresh water fractions in the surface water of the western arctic ocean evaluated from total alkalinity Gao Zhongyong，Sun Heng，Chen Liqi，Zhang Fan 2012, 24 (2):  120-128.  DOI: 10.3724/SP.J.1084.2012.00120 Abstract ( 2894 )   PDF (5278KB) ( 1542 )   As a quasi-conservative tracer, total alkalinity (TA) could trace freshwater and seawater. In this study, fractions of sea ice meltwater, river runoff, and seawater in the surface water of western Arctic Ocean are determined from salinity and total alkalinity relationships based on the Third Chinese Arctic Research Expedition during the summer of 2008. The largest fraction of sea ice meltwater was found around 75°N in the Canada Basin, the ice edge zone during survey, where ice concentrations increased northward gradually. The presence of river runoff was associated with the circulation, accumulated in the western Arctic Ocean. Related Articles | Metrics

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Sporadic E morphology in Antarctica Zhao Haisheng，Xu Zhengwen，Wu Jian 2012, 24 (2):  129-135.  DOI: 10.3724/SP.J.1084.2012.00129 Abstract ( 3057 )   PDF (3242KB) ( 1431 )   Es (Sporadic E) layers are ionization enhancements in the E region of ionospheres, whose electron density can achieve one hundred times of background E in some times. Es layers intensity and appearance probability are anomalous on the earth, which mostly distribute in the midlatitude and lowlatitude. In the polar region, the Es layers are also strong and have unique characteristics. The study of polar region Es is very important for researching the physical mechanism of Es. This paper using the observation data of station Syowa (69.0°S, 39.6°E) in Japan, which is more than 40 years, has studied the intensity characteristics, the day changes, the season changes and the longtime changes of the Es in Antarctica using h’Es and foes. Related Articles | Metrics

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Vertical structure of the low level atmosphere around the Southeast Indian Ocean fronts Liu Lin，Gao Libao 2012, 24 (2):  136-142.  DOI: 10.3724/SP.J.1084.2012.00136 Abstract ( 2469 )   PDF (5342KB) ( 1260 )   New GPS radiosonde system was launched to detect the vertical structure of the atmosphere around the southeast Indian Ocean fronts region during the 25th Chinese Antarctic expedition. The detailed information regarding vertical profile of wind speed and air temperature above fronts between Chinese Zhongshan Station and Frementle port was described for the first time. The research reveals that the distinct vertical structure appeared at the warm/cold side of subantarctic front between Chinese Zhongshan Station and Frementle port, the low level wind speed of warm side was stronger than the cold one, which confirmed the special atmosphere-ocean interaction at the front area in the southeast Indian Ocean region. A low-level jet was observed above the subantarctic front between Chinese Zhongshan Station and Frementle port. Vertical structure of the atmosphere around the Antarctic front is quite different compared with the subantarctic front. Related Articles | Metrics

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Using biomarkers in sediments as indicators to rebuild the phytoplankton community in Prydz Bay, Antarctica Yu Peisong，Zhang Haisheng，Hu Chuanyu，Lu Bing 2012, 24 (2):  143-150.  DOI: 10.3724/SP.J.1084.2012.00143 Abstract ( 2726 )   PDF (1818KB) ( 1673 )     In this study, biomarkers, including brassicasterol, dinosterol and alkenone, in sediments were used as indicators to rebuild the changes in the phytoplankton community in the upper water columns of Prydz Bay, Antarctica. Records of biomarkers in surface and core sediment samples showed obvious changes at spatial and temporal scales. The biomass of phytoplankton determined from biomarkers ranged from 391.0 to 1470.6ng/g. The ocean primary productivity has increased in Prydz Bay over the past 100 years and this increase was closely related to the changing climate in this area. The total content of biomarkers in surface sediments from Prydz Bay and its adjacent area ranged from 215.8 to 1294.3ng/g. The rebuilt biomass of phytoplankton in Prydz Bay was higher than that outside the bay, which agreed with the distributions of chlorophyll a (Chl a), organic carbon and biogenic silica measured in surface waters using in situ observations. This consistency supports the use of biomarkers in sediment to reflect biogeochemical processes in the upper seawater. Related Articles | Metrics

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Nutrient status and phytoplankton-pigments response to ice melting in the Arctic Ocean Zhuang Yanpei，Jin Haiyan，Chen Jianfang，Wang Bin，Li Hongliang，Chen Fajin，Lu Yong，Xu Jie 2012, 24 (2):  151-158.  DOI: 10.3724/SP.J.1084.2012.00151 Abstract ( 2343 )   PDF (2799KB) ( 1655 )   During the 4th Chinese National Arctic Expedition cruise in summer 2010, in a high Arctic, a time-series observation was carried out in order to examine the response of nutrients and phytoplankton in the ice-ocean interface to the ice melting. Phosphate and silicate in the ice-ocean interface were rich relative to nitrogen, based on Redfield ratio (16N:1P:16Si), suggesting that nitrogen was the potential limiting nutrient. Nitrogen concentration in the sea ice was about 3-4 times that in the surface seawater, indicating that melting water delivered nitrogen to the surface water. Pigments analysis showed that fucoxanthin and chlorophyll a were the main contributor of carotenoids and chlorophylls in particles, respectively. The mean concentrations of chlorophyll c, diatoxanthin, diadinoxanthin and fucoxanthin during 15 to 18 August were 6, 22, 73 and 922 μg/m3, respectively, suggesting that diatoms dominated in the phytoplankton community composition. Furthermore, a notable enhancement in fucoxanthin and chlorophyll a during a large-scale melting was likely attributed to senescent diatoms released from the bottom sea-ice as well as phytoplankton diatoms growth in the water column due to the input of nutrients (i.e. nitrogen) from melting water. Temporal distribution pattern of diagnostic pigments prasinoxanthin and lutein differed from fucoxanthin, indicating that green algae and diatoms responded differently to ice melting. Related Articles | Metrics

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A Mid-Late Holocene Lake Biomass Record in Larsemann Hills, East Antarctic Luo Yuhan，Liu Yi，Sun Liguang 2012, 24 (2):  159-167.  DOI: 10.3724/SP.J.1084.2012.00159 Abstract ( 3129 )   PDF (3134KB) ( 1637 )   The geochemical analysis was performed on a sediment core, named ZH, in Mochou lake in the Larsemann Hills, East Antarctic. The chronology was established based on AMS14C dates. The high resolution records of lake biomass were retrieved from the loss on ignition at 550℃(LOI550℃), grain size and geochemical element indexes. The results showed High Biomass Period at 6600-6100 yr BP, 5400-4800 yr BP, 4650-3750 yr BP and 3500-2850 yr BP in Mochou lake with warm and humid climate and high lake productivity, while Low Biomass Period at 6100-5400 yr BP, 4800-4650 yr BP and 3750-3500 yr BP with cold and arid climate as well as low lake productivity. There were also evidences of the rapid cooling events around 4850-4650 yr BP, 4400 yr BP and 3750-3500 yr BP, which were rarely reported from other ice-free regions of East Antarctic. Overall, the biomass of Mochou lake provide higher resolution climate characters of Larsemann Hills and a new evidence for the climate pattern of Mid-Late Holocene in East Antarctic. References | Related Articles | Metrics

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Optimization of growing conditions and extraction method of the crude carotenoids produced by Rhodococcus sp.B7740 isolated from Arctic sea Zhang Jiarong，Yang Jifang，Chen Fusheng 2012, 24 (2):  168-177.  DOI: 10.3724/SP.J.1084.2012.00168 Abstract ( 2660 )   PDF (1586KB) ( 1603 )   Rhodococcus sp.B7740 strain isolated from the Arctic ocean can accumulated large numbers of yellow pigments, which biomass is very low. In this study, optimal medium was obtained by singer factor and orthogonal experiment about carbon and nitrogen sources, temperature, initial pH and inoculum concentration. On this biasis, extraction conditions were optimized through about type of extraction solvent, pH, extraction time and solid to liquid ratio. The results showed that under the condition of 1L old sea water containing yeast extract5g, glucose5g, lactose3g, beef extract7g, with initial pH7, temperature 25℃, inoculum concentration1.0%, cultured 7daies on a shaker with a speed of 160r/min biomass of B7740 from 6.1mg/mL raised to 23.08mg/mL, an increase of 278.4%. Dry cells were used as material. Anhydrous ethanol with pH7 was the extracting reagent with ratio of sample to solution 1:30, temperature 75℃，extraction time 1h repeated for 2 times. In this case, the output of the pigment reached 1160.625μg/g dry sells. Analysis showed that the pigment was Carotenoid. The experiment results provided the foundation for the further study of extraction method about carotenoids produced by polar microbial Rhodococcus sp. B7740 strain. References | Related Articles | Metrics

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Distribution of nutrients and Chla in Prydz Bay during the austral summer of 2011 Sun Weiping，Hu Chuanyu，Han Zhengbing，Pan Jianming，Weng Huanxin 2012, 24 (2):  178-186.  DOI: 10.3724/SP.J.1084.2012.00178 Abstract ( 3161 )   PDF (4632KB) ( 1565 )   Water samples in Prydz Bay were collected during the Antarctic summer of 2011 and the contents of Chla and nutrients were analyzed. The results showed that the distribution of Chla in the surface water of Prydz Bay was: margin of ice shelf> continental shelf>continental slope and open sea, melting of ice and stability of water body were the main factors that had influence on the Chla distribution in the surface water. The vertical distribution of Chla was relate to the irradiation condition, mostly upper water had high content and decreased with the depth。Horizontal and vertical distribution of phosphate, silicate and nitrate was contrary to that of Chla. Distribution of ammonium in the surface water was contrary to that of main nutrients. The vertical distribution of ammonium at the margin of ice shelf and in the continental shelf was different with that in the continental slope and open sea. The degradation of organic matters mainly control the ammonium content in the water column at the margin of ice shelf and in the continental shelf, however the balance between uptake by phytoplankton and degradation of organic matters controlled that in the continental slope and open sea. According to the contents and distribution of Chla and nutrients, the cause of DCM and the inhibition of ammonium on nitrate uptake in the surface water south of 67.5°S were discussed. References | Related Articles | Metrics

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THE PROGRESS OF EXPEDITIONS AND RESEARCHES IN THE SEAS RELATED TO THE ARCTIC PASSAGES He Jianfeng，Wu Rongrong，Zhang Fang，Wang Yong，Yu Yong 2012, 24 (2):  187-196.  DOI: 10.3724/SP.J.1084.2012.00187 Abstract ( 2666 )   PDF (8867KB) ( 1217 )   Since 1999 China has implemented four Arctic expeditions on the Bering Sea, Chukchi Sea, Beaufort Sea, Canada Basin, and Makarov Basin. Global change has been causing the declining of sea ice coverage in the Arctic Ocean in summer, leading to the opening of Northeast and Northwest Passages at the same time. The Arctic shelf seas where the Passages located, is not only the area with most significant sea ice changes, but also with the most significant land-ocean interaction. It has significant impact on the Arctic regional climate, ecosystems and biodiversity, and the local economy and indigenous people. This study summaries the scientific investigations in the main area of the Passages in recent years, provides the comments of Chinese Arctic cruises in the Passage area in the future according to the viewpoint of the scientific researches. Related Articles | Metrics

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The X- and L-Band Remote Sensing Reception System and Its Applications in Antarctica Research in China GreatWall and ZhongShan Station, Antarctic Zhang Lin，Sun Qizhen，Xu Cong，Yang Qinghua 2012, 24 (2):  197-203.  DOI: 10.3724/SP.J.1084.2012.00197 Abstract ( 3141 )   PDF (4641KB) ( 1632 )   Satellite remote sensing data plays an important role in Antarctic research. In the end of 2009 and the beginning of 2010, two same satellite reception systems from Australia ES&S Company were established in China GreatWall and ZhongShan station in Antarctica, respectively. These high-performance dual X- and L-band systems, which track, receive and process data from the NASA Terra and Aqua satellites (with MODIS data), the NOAA, and the Fengyun-1 series satellite, will be a powerful tool in varied studying subject areas including Antarctic weather, snow cover, sea ice and ecology in Southern Ocean. In this paper, the composition, operating and the products of the systems are introduced, followed by the current and future applications in the study of Antarctic katabatic wind, snow cover and the albedo, and atmospheric and oceanic numerical models etc. Related Articles | Metrics