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30 December 2012, Volume 24 Issue 4 Previous Issue    Next Issue

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A REVIEW OF ADVANCES IN SEA-ICE DISCRETE ELEMENT MODELS JI Shunying，LI Chunhua，LIU Yu 2012, 24 (4):  315-330.  DOI: 10.3724/SP.J.1084.2012.00315 Abstract ( 2480 )   PDF (9189KB) ( 1167 )   In order to describe the discrete nature of sea ice at different scales, sea ice discrete element models have been developed since 1980s. In this study, three scales of sea ice are divided as geophysical scale (~100km), floe scale (~10km) and structure scale (1m~100m). On each scale, the discrete distribution and dynamic process from continuous to discrete state of sea ice are presented. Sea ice discrete element models in terms of blocks, disks and particles are introduced, and their application in dynamic characteristics of sea ice in polar regions, simulation of sea ice rafting and ridging and the interaction with wave, interaction between sea ice and structures, and sea ice mechanical properties modeling are analyzed. Sea ice strength due to scale effect is discussed. Finally, future studies on sea ice discrete element models are suggested. References | Related Articles | Metrics

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SPECIES COMPOSITION AND DISTRIBUTION OF DIATOMS IN SURFACE SEDIMENTS OF BERING SEA Shao Lixia, Lin Rongcheng, Gao Yahui, Huang Dingyong 2012, 24 (4):  331-338.  DOI: 10.3724/SP.J.1084.2012.00331 Abstract ( 1944 )   PDF (2997KB) ( 891 )   Abstract Based on 6 surface sediment samples, which were collected in the Being Sea during the Forth Chinese Arctic Expedition, a total of 101 diatom species (including varieties and forms) belonging to 37 genera had been detected. These species can be sorted into four ecological groups:（1）Eurythermal group;（2）Boreal-temperate group;（3）Polar group; and（4）Sea-ice group. In the basin area, diatoms were dominated by boreal-temperate group, including Neodenticula seminae、Thalassiosira trifulta、Rhizosolenia hebetata f. hiemalis and Actinocyclus curvatulus. However, in the northern shelf area, they were mainly polar group with the dominant species of Fragilariopsis oceanica、Thalassiosira antarctica spora、Thalassiosira nordenskioeldii and Thalassiosira hyaline. Diatom concentrations show the maximum of 3.6×106 cells per gram wet sediment in the basin and minimum of 0.7×106 cells per gram wet sediment in the eastern shelf, excluding resting spores of Chaetoceros spp. The relationship between the distribution of diatoms in surface sediment and environmental factors was discussed in this study. References | Related Articles | Metrics

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THE SOLUBILITY OF BIOGENIC SILICA IN THE SEDIMENT OF PRYDZ BAY，THE SOUTHERN OCEAN Hu Chuanyu，Sun Weiping，Shen Chen，Zhang Haisheng 2012, 24 (4):  339-345.  DOI: 10.3724/SP.J.1084.2012.00339 Abstract ( 2115 )   PDF (2288KB) ( 950 )   Laboratory-based solubility determinations of biogenic silica have been performed in batch reactors on sediments from two cores collected in Prydz Bay of the Southern Ocean. The results show that the apparent solubility of BSi(biogenic silica) in the top sediments of IV-10 and IS-4 station were 1930 μmol/dm3 and 1540μmol/dm3, respectively, and decrease with depth in the core. The apparent solubility of BSi were much higher than the value of Cd of DSi (dissolved silica) in pore water. The pore water distributions of DSi record early diagenetic histories that may involve chemical interactions other than simply the dissolution of the deposited BSi. References | Related Articles | Metrics

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THE BIOLOGY OF ELECTRONA ANTARCTICA IN THE WESTERN SOUTH ORKNEY ISLANDS, ANTARCTIC Zhu Guoping, Li Fengying, Feng Chunlei, Wu Qiang, Xu Pengxiang, Xu Liuxiong 2012, 24 (4):  346-351.  DOI: 10.3724/SP.J.1084.2012.00346 Abstract ( 2084 )   PDF (1406KB) ( 1084 )   Based on the biological data collected in the western South Orkney Islands, Antarctic in austral summer, 2010-2012, the present study analyzed the biological characteristics of Electron antarctic (Electrona antarctica), including standard length (TL), wet weight (WW), dressed weight (DW), the relationship between SL and DW, sexual maturity stage and gonadsomtic index. The results showed that: (1) The SL ranged from 6.3 to 8.8 cm and the average SL value is 7.51±0.03cm (95% confidence interval), the WW ranged from 3.46 to 10.13 g and the average WW is 5.96 ± 0.08 g, the DW ranged from 3.11 to 8.69 g and the average DW is 5.17 ± 0.07 g. (2) The relationship between WW and DW was DW=0.8497TW+0.1623 (R2=0.9502), and the relationship between SL and DW was FL=0.0238DW2.6695. (3) During the survey period, the sexual maturity stages of Electron antarctic were from stage I to IV and stage V and VI cannot be found. (4) The feeding intensity of Electron antarctic was increased with the increasing of SL, the proportion of empty stomach and stage I were decreased with the increasing of SL. Related Articles | Metrics

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THE ABUNDANCE INDEX OF ANTARCTIC KRILL AND ITS RELATIONSHIP TO SEA ICE AND SEA SURFACE TEMPERATURE Dai Lifeng, Zhang Shengmao, Fan Wei 2012, 24 (4):  352-360.  DOI: 10.3724/SP.J.1084.2012.00352 Abstract ( 2536 )   PDF (3607KB) ( 1394 )   According to Antarctic krill catch data from 1997 to 2010 in Area 48.2 and sea ice and SST data, this paper analyzed the spatio-temporal distribution of krill catch and discussed the influence of sea ice and SST on abundance of Antarctic krill. The results show that annual krill catch in Area 48.2 dominatingly came from March to July, and mainly fishing time was from February to August, and the production during this period accounting for about 99.3% of the annual catch. Regression analysis shows that CPUE of Antarctic krill had obvious relations with the area of sea ice and SST. CPUE was negatively related with the total area of sea ice among years (R=0.80), and the correlation is maximum (R=0.84) with the area of sea ice where concentrations were between 90% and 100%; they had a second polynomial regression model among months, and CPUE increased firstly then decreased with the increasing of the area of sea ice, and the correlation is maximum (R=0.94) with the area of sea ice where concentrations were between 60% and 70%. The negative correlation among years was unremarkable between CPUE and the area of SST where the values were between -2℃ and 3℃(R=0.46), but CPUE had significant negative correlation with the area of SST where the values were between 1℃ and 2℃ (R=0.91); they also had a second polynomial regression model among months, and CPUE increased firstly then decreased with the increasing of the area of SST, and the correlation is maximum (R=0.97) with the area of sea ice where concentrations were between 0℃ and 1℃. References | Related Articles | Metrics

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SPATIAL AND TEMPORAL VARIABILITY OF CHLOROPHYLL A DURING THE AUSTRAL SUMMER IN PRYDZ BAY, ANTARCTICA Jin Siyun, Pan Jianming, Han Zhengbing 2012, 24 (4):  361-371.  DOI: 10.3724/SP.J.1084.2012.00361 Abstract ( 2427 )   PDF (5638KB) ( 1498 )   Making use of the chlorophyll-a (Chl-a) and sea surface temperature (SST) derived from SeaWiFs and MODIS satellite ocean color date, and combining with the data in situ by Chinare, it discussed the distributions of SST, Chl-a and nutrients in austral summer in Prydz Bay, and the influencing factors were analyzed. As it turns out, the distribution of surface Chl-a in Prydz Bay showed significant characteristics, the surface Chl-a concentrations decreased offshore. In the shelf area, the bloom of phytoplankton was affected by the ablation of sea ice and the supply of nutrients. In the slope area, the growth of phytoplankton was mainly affected by the hydrological conditions. And in outside the Bay, the Chl-a concentration was much lower, and it was influenced by the lack of iron probably. In the last decade, the average of Chl-a concentrations of remote sensing were 1.40, 0.44 and 0.25 mg/m3 from the shelf to the outside, respectively. In astral summer, a high positive correlation between Chl-a with SST was founded in Prydz Bay, R2=0.505. The annual concentration variation showed that the Chl-a trended strongly related with SST, revealing that the temperature was the main factor. Using the relationship between the Multivariate ENSO Index (MEI) and the Chl-a concentration inner shelf area, it demonstrated that Chl-a concentration was much higher when EL Nino happened than that when La Nina happened, revealing that the growth and reproduction of phytoplankton at high-latitude has remarkable response with the ENSO occurred at Middle and low latitudes. References | Related Articles | Metrics

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DIVERSITY ANALYSIS OF FUNGI ISOLATED FROM NY-ÅLESUND, SVALBARD, AND SCREENING FOR BIOTRANSFORMATION OF GENTIOPICROSIDE Xu Dan, Ma Jifei, Miao Zhen, Li Huirong, Chen Bo 2012, 24 (4):  372-383.  DOI: 10.3724/SP.J.1084.2012.00372 Abstract ( 2221 )   PDF (4609KB) ( 1326 )   65 strains of fungi isolated from the arctic high-latitude soil and marine sediments were investigated. Their phylogenetic diversity were analyzed by their 18S rDNA sequencing. Classification of 65 fungi strains based on 18S rDNA gene showed that these fungi represented 26 genera, of which the number of Penicillium was the most of 19 strains ,followed by Nectria and Articulospora ,with 6 strains respectively.The strains which can transform gentiopicroside were screened. β-glucosidase was chosen as marker enzyme to screen the positive strains. And 28 strains were tested to produce it. Among them, 9 strains were selected to transform gentiopicroside. And the crude extracts of them ware tested by TLC and HPLC. Ultimately strain C-5 was determined as the biotransformation strain. According to the morphological features and nucleic acid sequences analysis, strain C-5 was identified for the genus of Penicillium. It was tentatively named as Penicillium sp.C-5. References | Related Articles | Metrics

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GEOCHEMICAL ANALYSIS TO DETERMINE THE SOURCES OF LAKE SEDIMENTS FROM AMANDA BAY, EAST ANTARCTICA Huang Tao, Sun Liguang 2012, 24 (4):  384-390.  DOI: 10.3724/SP.J.1084.2012.00384 Abstract ( 2396 )   PDF (1253KB) ( 1005 )   Two short lake sediment cores EPI and PI were collected at N island, Amanda Bay, East Antarctica during 2007-2008 seasons. The lithology and sedimentology of EPI profile indicate that it was a dominance of peat deposit. The PI sediments were composed of black mud, contained many penguin feathers and bones, and had a strong and unpleasant smell of penguin guano. Elemental concentrations were analyzed on the sediments of EPI and PI, local bedrock and lake algae. The results indicate that elemental concentrations in the sediments of EPI were contributed mainly from bedrock and lake algae. The abundance of TC, TN, TP, Cu, Zn, Hg and Se in PI sediments were much higher than those in local bedrock, they were mainly from emperor penguin guano input while element Pb was contributed mainly from geochemical background. For the first time, this study demonstrates that emperor penguin transports a lot of marine-derived nutrients as well as much heavy metal pollutants onto lake ecosystems. References | Related Articles | Metrics

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210Pb-DERIVED ORGANIC CARBON DEPOSITION FLUX ON THE NORTH CHUKCHI SHELF Yu Wen，He Jianhua，Li Yiliang，Su Jian 2012, 24 (4):  391-396.  DOI: 10.3724/SP.J.1084.2012.00391 Abstract ( 1837 )   PDF (1322KB) ( 1177 )   Deposition of organic carbon forms the final net effect of the ocean carbon sink in a certain time scale, and the organic carbon deposition of Arctic shelf plays a particularly important role in the global carbon cycle due to its broad shelf area. In order to determine the organic carbon deposition flux at the north margin of Chukchi shelf, 210Pb dating method was applied to analyze the age and deposition rate of sediment samples from station R17 of the 3rd Chinese National Arctic Research Expedition. The results show that the deposition rate was 0.6 mm/a, the apparent deposition mass flux was 0.72 kg/m2/a, and the organic carbon deposition flux was 517 mmol C/m2/a, respectively. It was estimated that 29 % of the export organic carbon flux out of the euphotic zone was transferred and chronically buried into the sediment, which was much higher than the average ratio (~ 10 %) of the low-/mid-latitude region, indicating a highly effective carbon sink at the north margin of Chukchi shelf. References | Related Articles | Metrics

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INITIAL RESULTS FROM THE ZHONGSHAN HF RADAR IN ANTARCTICA LIU Erxiao, HU Hongqiao, LIU Ruiyuan, WU Zhensen, WU Mingjun, YANG Huigen, ZHANG Beichen 2012, 24 (4):  397-407.  DOI: 10.3724/SP.J.1084.2012.00397 Abstract ( 2266 )   PDF (6711KB) ( 1165 )   The HF coherent scatter radar is one of the most powerful tools to probe the ionosphere convection. Zhongshan HF radar has been built and operational since April, 2010 and became one of the SuperDARN radars. Firstly, the operational principle and mode of Zhongshan HF radar in Antarctica have been introduced, then the distribution of ionospheric echoes at each of 16 beams and the variation of ionospheric echoes with frequency have been analyzed with the first year’s observation. Finally, the occurrence of ionospheric echoes in different frequencies has been presented. The results from observation and simulation by ray tracing show that, statistically, the difference of ionospheric echoes occurrence between beams for different frequencies is arising from the direction of beam pointing and the area that the beam can achieve the orthogonality condition between the wave vector and the earth’s magnetic field. References | Related Articles | Metrics

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THE DEVELOPING TENDENCY OF ACTIC SCIENCE AND TECHNOLOGY BASED ON THE ARCTIC POLICIES OF ARCTIC NATIONS He Jianfeng Zhang Fang 2012, 24 (4):  408-414.  DOI: 10.3724/SP.J.1084.2012.00408 Abstract ( 2181 )   PDF (524KB) ( 1604 )   Due to the impact of climate change, vast economic potential, as well as change of geopolitical significance, the Arctic region is rapidly becoming the focus of attention of the Arctic nations and even the nations in the northern hemisphere. Since the end of 2006, Norway, Russia, the United States, Canada, Finland, Iceland, Sweden and Denmark, Arctic eight countries launched their Arctic new policies and strategy. They elaborated on Arctic sovereignty, resource usage, environmental protection, socio-economic development and indigenous rights, etc. At the same time, they emphasized the significant role of the scientific research and technological development in the local ecological and environmental protection, and sustainable economic development. The research priority areas were clarified to guide countries in Arctic science and technology development and service interests in the Arctic. Based on the new Arctic policies and strategy in the Arctic countries, analysis of Arctic science and technology development priorities and trends were carried out in the text. Combined with Chinese existing Arctic scientific researches and cooperation basis, China's Arctic science and technology development priorities and proposals for cooperation were also suggested in the text. References | Related Articles | Metrics

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A REVIEW OF PROGRESS IN THE STUDY OF VIRIOPLANKTON IN THE POLAR ZONE Li Hongbo 2012, 24 (4):  415-422.  DOI: 10.3724/SP.J.1084.2012.00415 Abstract ( 2561 )   PDF (850KB) ( 1150 )   Study on marine virioplankton in polar zones home and abroad is summarized in this paper, and the effect of climate change-seaice melting on the polar virus ecology, including the impact on abundance and diversity of virioplankton, and the role of virus in carbon cycle in polar regions also are disscussed. On the other hand, the methods about virus abundance, viral decay rate, viral production, and the roles in bacterial mortality rate induced by viral lysis, are expounded in detail. Although the study on virus ecology is scarce in China, the interrelated work, e.g. primary production, bacterial production, microbial food loop and so on, have been done much. At the end, several questions about virus ecology in polar zones are put forward, and wish to be solved in the future. References | Related Articles | Metrics