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30 June 2016, Volume 28 Issue 2 Previous Issue    Next Issue

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U-Pb zircon chronology of high-pressure granulites and orthogneisses from glacial moraines in the Grove Mountains, East Antarctica 2016, 28 (2):  159-180.  DOI: 10.13679/j.jdyj.2016.2.159 Abstract ( 755 )   PDF (7477KB) ( 692 )   High-pressure granulites and orthogneisses from glacial moraines in the Grove Mountains, East Antarctica, were collected for zircon U-Pb isotope analysis. The zircon grains from four high-pressure granulites were mostly of metamorphic origin. However, some contained an inherited core aged 2633–2502 Ma. The metamorphic zircons showed two age stages (~570 Ma and ~555–545 Ma representing the earlier prograde and peak HP metamorphism ages, respectively) and displayed flat HREE patterns in the chondrite-normalized REE diagram. The zircon grains from two orthogneisses typically showed a magmatic core with oscillatory zoning and a metamorphic rim without zoning. Different protolith ages were obtained from zircon cores of these two orthogneisses. An upper intercept age of 1060 ± 40 Ma was obtained from the cores of zircon in one sample, suggesting that its protolith came from the subglacial highlands in the southeast Grove Mountains. Analytical spots from another sample yielded a protolith age of 917 ± 4 Ma, consistent with the protolith ages obtained for orthogneisses and mafic granulites that crop out in the Grove Mountains. The analytical spots from zircon rims from the two orthogneisses yielded similar metamorphic ages of ~530 Ma, in agreement with the time of retrograde metamorphism of high-pressure granulites reported previously. High-pressure granulites were common in glacial moraines from the Grove Mountains, reflecting their widespread occurrence in the subglacial highlands. Moreover, U-Pb zircon dating confirmed that the subglacial highlands of the Grove Mountains underwent a single Pan-African metamorphic cycle, but there was no evidence of a Grenville-age metamorphic event. Related Articles | Metrics

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Ecological characteristics of zooplankton communities in the Western Arctic Ocean in summer of 2012 2016, 28 (2):  181-193.  DOI: 10.13679/j.jdyj.2016.2.181 Abstract ( 1034 )   PDF (3125KB) ( 1264 )   Arctic Ocean sea ice coverage reached a record minimum of 3.41 million km2 in 2012. Zooplankton samples collected from 22 stations during summer 2012 were analyzed to determine the composition and geographic distribution of various Arctic Ocean communities, and to identify relationships to environmental conditions. Three geographically distinct communities were identified. The southern Chukchi Sea (CS) community was dominated by barnacle larvae (total abundance 56.6%–79.8%), followed by copepods (18.0%–42.2%). The central and northern CS community was dominated by copepods (62.3%–96.8%) followed by barnacle larvae (0%–30.9%). The deep-sea community was dominated by copepods (71.6%–89.8%) and characterized by extremely low abundance. The zooplankton community at Station M06, located at the edge of the CS slope, could not be classified into one of the three communities. Abundance was similar to CS communities but composition was similar to deep-sea communities. Calanus glacialis, Pseudocalanus sp., Oikopleura vanhoffeni, and barnacle larvae were dominant in the two shallow water communities. There were more dominant species in the deep-sea community, mostly large copepods including Calanus glacialis, Calanus hyperboreus, and Metridia longa. Surface temperature and salinity were the most important environmental factors determining the geographical distribution of communities. There was no significant change in community patterns and geographic distribution compared to 2003 results (when sea ice coverage was higher), but total abundance of zooplankton in the CS increased up to 2-fold and total abundance decreased in the deep-sea community with an increase in the percentage of large copepods. Related Articles | Metrics

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Burial fluxes of biogenic materials in Bering Sea and Chukchi Sea 2016, 28 (2):  194-202.  DOI: 10.13679/j.jdyj.2016.2.194 Abstract ( 1082 )   PDF (1191KB) ( 1105 )   The Chukchi and Bering Seas are connected by the Bering Strait. To investigate the impact of climate change in this region, excess 210Pb was measured to compare sedimentary processes between the two seas. Results for the Bering Sea station demonstrated an effect from benthic fauna, whereas biological activity at the Chukchi Sea station was limited. The sediment accumulation rate was 0.6 ± 0.1 mm/a and 2.1 ± 0.07 mm/a in the Chukchi Sea and Bering Sea, respectively. The particle mixing coefficient related to benthic fauna at the Bering Sea station was 1.38 ± 0.92 cm2·a-1 without considering sediment processes and 0.65 ± 0.95 cm2/a considering sediment processes. Burial fluxes of organic carbon, biogenic opal, and CaCO3 in the Bering Sea were 6.85 mmol C·m-2·d-1, 37.7 mmol Si·m-2·d-1, and 3.15 mmol C·m-2·d-1, respectively, and in the Chukchi Sea were 5.71 mmol C·m-2·d-1, 9.78 mmol Si·m-2·d-1, and 3.08 mmol C·m-2·d-1, respectively. Vertical transport by a high efficiency marine biological pump characterized the Chukchi Sea station, whereas lateral transport was predominant at the Bering Sea shelf station. Therefore, 210Pb in marine sediments could be applied not only to quantify sediment accumulation rates and burial fluxes of biogenic materials but also to indicate the intensity of biological activity in benthic environments. Related Articles | Metrics

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Preliminary study on abundance and biomass of meiofauna in the Bering Sea in summer 2010 Huang Dingyong, Wang jianjia, Lin Rongcheng, Tian Peng, Zheng Xinqing 2016, 28 (2):  203-210.  DOI: 10.13679/j.jdyj.2016.2.203 Abstract ( 708 )   PDF (2558KB) ( 828 )   Surface sediments were collected from seven stations in the Bering Sea during the fourth Arctic Chinese National Arctic Research Expedition in summer 2010. Fourteen groups of meiofauna were detected in 10-cm sediment cores: Nematoda, Copepoda, Polycheata, Kinorhyncha, Amphipoda, Bivalvia, Cumacea, Ostracoda, Tanaidacea, Gastropoda, Isopoda, Ophiura, Tardigrada, and others. The average abundance and biomass was 2658.89 ± 2452.86 ind·10 cm-2 and 1587.56 ± 1452.65 μg·dwt·10 cm-2, respectively. Maximum abundance and biomass of 7135.12 ± 429.43 ind·10 cm-2 and 4056.42 ± 721.33 μg·dwt·10 cm-2, respectively, was observed in shallow waters of the Bering shelf. Minimum abundance and biomass of 56.04 ± 39.38 ind·10 cm-2 and 87.91 ± 85.60 μg·dwt·10 cm-2, respectively, was observed in deep waters of the western Bering Sea basin. Nematoda accounted for 94.81% of average abundance, followed by Copepoda (3.60%), and 93.44% of meiofauna were found in the upper 6 cm of surface sediments. The similarity index between meiofauna communities in shallow and deep waters was only 30.72%. Abundance in deep waters was an order of magnitude lower than abundance in shallow waters. Abundance and biomass were higher in shallow waters of the Bering shelf than in shallow waters of the China Sea and deep waters of the western Bering Sea basin. Pearson correlations analysis between meiofauna and abiotic parameters indicated that abundance and biomass were negatively correlated with depth, sediment nutrient levels, and several diameter parameters. Meiofauna biomass may be more sensitive to environmental changes than abundance. Related Articles | Metrics

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Preliminary investigation of the distribution of dimenthylsulfide(DMS) and dimethylsulfoniopropionate(DMSP) in coastal fast ice near Zhongshan Station of East Antarctica during the austral summer Zhang Miming, Chen Liqi, Xiao Zhenglin 2016, 28 (2):  211-218.  DOI: 10.13679/j.jdyj.2016.2.211 Abstract ( 728 )   PDF (2142KB) ( 871 )   The distribution of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) in ice cores was analyzed. The cores were drilled from coastal fast ice off Zhongshan station in East Antarctica during the 30th Chinese National Antarctic Research Expedition. The highest concentrations of DMSP + DMS were 114.93 nM and 134.41 nM, observed in the top layer of two ice cores. Both DMS and DMSP + DMS concentrations decreased from the top to bottom of the ice cores. There were two different factors controlling DMSP + DMS in the upper layer of the ice cores; one was related to algal assemblages, and the other was related to DMS accumulation in the slush layer. This DMS accumulation occurs because the ice and snow layer covering the sea ice blocks the emission of DMS into the atmosphere. Concentrations of chlorophyll a (Chl a) and DMSP + DMS were low in the bottom of ice cores because the bottom layer of sea ice with high biomass melts during the summer. During the sea ice melting season, gravity-related drainage of brine could alter the vertical distribution of Chl a and DMSP + DMS. The integrated Chl a and DMSP + DMS in ice cores analyzed during the present study (6.79–10.20 mg·m-2 and 51.83–88.41 μmol·m-2, respectively) were low compared with previous studies, indicating that the melt process could lead to a decline in biomass and DMSP + DMS in ice cores. Related Articles | Metrics

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The evolution of upper water structure in the Prydz Bay polynya region during Antarctic winter, 2011 Gao Guoping, Yan Minfei, Xu Zhixin, Cheng Lingqiao, Zhang Chunling 2016, 28 (2):  219-227.  DOI: 10.13679/j.jdyj.2016.2.219 Abstract ( 856 )   PDF (3595KB) ( 1051 )   Hydrographic data collected during the early Antarctic winter 2011 by CTD tags fitted to five elephant seals were analyzed to study the evolution of the upper water layer in the Prydz Bay polynya adjacent to the Amery ice shelf. The evolution of upper ocean structure could be divided into three stages. First, temperature shifted from a stratified profile to homogeneity. Warm water was still present in the subsurface in late March. This warm water gradually disappeared with cooling of the surface water, so the temperature profile evolved from temperature inversion to homogeneity at temperatures close to freezing. Second, salinity shifted from a stratified profile to homogeneity. Salinity increased with the freezing of seawater, which strengthened vertical convection and resulted in homogeneous salinity throughout the upper water layer. Third, seawater continued to cool and salinity continued to increase. Stratified profiles of temperature and salinity were reestablished. With increased depth, salinity decreased and temperature increased. Air–sea heat fluxes calculated from temperature and salinity profiles during the first, second, and third stages were -90.93 W m-2, -82.20 W m-2, and -43.44 W m-2, respectively. The increase in salinity was mainly the result of sea ice formation, and the sea ice formation rates were 5.4 cm d-1, 4.9 cm d-1, and 2.5 cm d-1, respectively. In summary, the present study demonstrated that during the early Antarctic winter, as temperatures in the upper water layer continue to decrease and salinity increases, the heat flux released from ocean to atmosphere and the sea ice formation rate gradually decrease. Related Articles | Metrics

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Comparative analysis of changes in sea ice extent in Ross Sea and Prydz Bay Shuai-Bin Liu Ze-Min WANG 2016, 28 (2):  228-234.  DOI: 10.13679/j.jdyj.2016.228 Abstract ( 871 )   PDF (5153KB) ( 1086 )   Changes in sea ice extent have a significant impact on climate change, ecosystems, and human activities, and the change in polar sea ice extent has created major concern in recent years. In this paper, sea ice extent in the Ross Sea and Prydz Bay in Antarctica were compared using time-series analysis. There were distinct differences in the patterns of seasonal variation in sea ice extent between the Ross Sea and Prydz Bay. The Ross Sea showed rapid decrease–rapid growth, while Prydz Bay showed rapid decrease–slow growth. However, annual variations in sea ice extent in both regions are increasing. The annual trend in the Ross Sea was (1.39 ± 1.12)×104 km2 a-1 while in Prydz Bay the trend was (0.61 ± 0.26)×104 km2 a-1 . The annual growth of winter sea ice extent was higher than that of summer sea ice extent in both areas, and the annual trend in the Ross Sea region showed negative growth in summer sea ice extent. Related Articles | Metrics

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Analysis of Global Navigation Satellite System broadcast ionospheric model correction in polar regions 2016, 28 (2):  235-242.  DOI: 10.13679/j.jdyj.2016.2.235 Abstract ( 784 )   PDF (2112KB) ( 978 )   Time delay in the ionosphere is the most important source of error in the Global Navigation Satellite System. In particular, the ionosphere in polar regions is changeable, resulting in reduced precision of global positioning systems (GPS). Therefore, an appropriate broadcast ionospheric model is needed for the polar regions. Vertical total electron content data were derived from the GIM model, and the effects of two correction models (two versions of the Klobuchar model adopted by GPS and the BeiDou Navigation Satellite System [BDS], and the NeQuick model) on the ionospheric delay of positioning accuracy were compared. At latitudes higher than 57.5°N or S, the Klobuchar model adopted by GPS had a negative effect in most cases, but performed better than that adopted by the BDS. The NeQuick model performed worse at high latitudes than at middle and low latitudes, with a correction effect of about 40%. Related Articles | Metrics

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Derivation of ice-flow velocity of Polar Record Glacier using an improved NCC algorithm Niu Muye, Zhou Chunxia, Liu Tingting 2016, 28 (2):  243-249.  DOI: 10.13679/j.jdyj.2016.2.243 Abstract ( 796 )   PDF (3118KB) ( 897 )   The ice-flow velocity of Antarctic glaciers play an important role in the mass balance study of Antarctic. In this study, a rotation parameter of SIFT algorithm was added into a traditional ice-flow velocity derivation method based on Normalized Cross-Correlation algorithm, making the method with rotation invariance. Based on this improved method, the ice-flow velocity of Polar Record Glacier in East Antarctica was derived using Landsat8 OLI data. Accuracy assessment was done using simulated data and MEaSUREs velocity data released by NASA. The results indicated that in the direction of velocity changed area, more ice-flow velocity can be derived. The maximum velocity of Polar Record could reach 870m/a. Compared with the MEaSUREs data, the average offset is 23.9m/a. Related Articles | Metrics

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Incorporation of resilience engineering theory into risk prevention and control in polar waters 2016, 28 (2):  250-256.  DOI: 10.13679/j.jdyj.2016.2.250 Abstract ( 761 )   PDF (951KB) ( 1346 )   Navigation in polar waters is complex, with numerous potential hazards and emergency scenarios. Ships operating in polar waters face challenging environmental factors including marine icing, cold temperatures, electromagnetic distortion, high winds, and low visibility. Resilience engineering is a recently developed system theory applied to the field of safety science. Resilience is the ability of a system to withstand a major disruption with acceptable degradation parameters, and the ability to recover within an acceptable time frame and with acceptable composite costs and risks. A resilient system depends on four abilities: learning, anticipation, monitoring, and response. The Navigational Risk Prevention and Control Resilient System in Polar Waters (NRPCRS-PW) is proposed to minimize the occurrence of marine transportation accidents in polar waters, to improve navigational risk prevention, and to control navigational ability. The NRPCRS-PW is developed according to the major connotations of resilience engineering and navigational risk in polar waters. The concepts and dependencies of resilience abilities related to environment and the key technologies of NRPCRS-PW are discussed based on five steps: environmental analysis, vulnerability mechanisms, risk forecasting, state monitoring, and crisis response. This research presents a method to improve risk control capacity in polar waters, which in turn contributes to safe, convenient, effective, and environmentally sensitive maritime transportation. Related Articles | Metrics

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Arctic sea ice ablation，Arctic circumpolar countries，game theory，dynamic dispute model 2016, 28 (2):  257-266.  DOI: 10.13679/j.jdyj.2016.2.257 Abstract ( 882 )   PDF (2116KB) ( 1021 )   Continued elevated temperatures are a major feature of global climate change and are associated with a marked increase in Arctic sea ice melting. The decrease in Arctic sea ice resulting from increased melting has resulted in access to abundant resources, has opened a convenient navigation channel through the Arctic region, and has impacted strategic and military operations. The United States, Russia, Canada, Norway, and Denmark are all seeking benefits related to the reduction in Arctic sea ice. A dynamic model based on game theory was constructed to explore acts of cooperation and conflict among the Arctic circumpolar countries in the harnessing of these benefits. This model included comprehensive consideration of factors including climate change, material benefits, national relations, national prestige, and international laws and regulations. This dynamic game model was used to simulate and predict the outcomes of different patterns of cooperation in the scenario of complete loss of Arctic sea ice. Related Articles | Metrics

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Strategic thinking on China’s involvement in the development of Arctic sea routes 2016, 28 (2):  267-276.  DOI: 10.13679/j.jdyj.2016.2.267 Abstract ( 1048 )   PDF (4432KB) ( 1286 )   The development of Arctic sea routes offers important strategic value for China and represents an extension to the Silk Road Economic Belt and the 21st-Century Maritime Silk Road (B & R). The Northeast Passage (NEP), Northwest Passage (NWP), and Trans-Polar Passage (TPP) are compared from the viewpoint of shipping conditions, laws, and geopolitics, and preliminary suggestions are made for strategic choices around the utilization of Arctic sea routes. The main findings are as follows: (1) In recent years, although world trade and shipping have declined, Arctic shipping has tended to increase. With the continued decline in Arctic sea ice, the era of independent Arctic navigation is approaching. (2) The three Arctic navigation routes are in different stages of development. The NEP is developing rapidly with a small but stable base of bulk cargo and oil shipping. The NWP is developing slowly with resource-related bulk cargo shipping. Trans-Polar shipping via the TPP is minimal but has attracted increasing attention in recent years. (3) The ideal development strategy for China in terms of Arctic sea routes is to use one, try one, and explore one. There should be substantial investment in the NEP, tentative investment in the NWP, and exploratory investment in the TPP. China–Europe container transport via the Arctic is the most important area of investment. (4) Development and utilization of Arctic navigation routes require scientific investigation and commercial utilization and China should take the approach of integration and exploration to develop and utilize Arctic sea routes. Related Articles | Metrics

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A review of the use of ice penetrating radar to diagnose the subglacial environnments Yang Shuhu,Gu Qiming,Zhang Yun,Cui Xiangbin,Tang Xueyuan 2016, 28 (2):  277-286.  DOI: 10.13679/j.jdyj.2016.2.277 Abstract ( 1030 )   PDF (843KB) ( 1412 )   The subglacial environment in Antarctica has important effects on the evolution of the Antarctic ice sheet. Accurate information on the subglacial environment information will therefore enable more accurate simulation of the evolution of the ice sheet. Currently, radio echo sounding is the most effective technique available to investigate the development of ice sheet. The subglacial environment, in particular the hydrological environment, can be monitored based on bed reflectivity, which is measured by quantitative analysis of the dielectric attenuation of radar waves in the ice sheet. Three methods used to process radar wave attenuation in the ice sheet are reviewed, the applicability and limitations of these methods are analyzed, the subglacial environment is determined using each method, and potential improvements are discussed. Related Articles | Metrics

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The impact of different methods for monthly mean boundary extraction on trends in Antarctic sea ice Shi Zhongyu， Pang Xiaoping， Zhao Xi，Cheng Zi’an，Ji Qing 2016, 28 (2):  287-294.  DOI: 10.13679/j.jdyj.2016.2.287 Abstract ( 680 )   PDF (4238KB) ( 898 )   The boundary zone between sea ice and open water is an area where ocean, ice, and atmosphere meet and interact. To analyze sea ice changes over long time series, it is important to identify the sea ice boundary and to obtain data on parameters such as sea ice extent, area, and ice perimeter. Passive microwave imaging is the preferred method to obtain data for long-term monitoring of sea ice changes. Based on classical statistics and random set theory, three different average methods are proposed to extract monthly sea ice extent from daily passive microwave sea ice concentration data. The impact of the differences in these models for long-term analysis of sea ice changes is discussed. Related Articles | Metrics

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Database of 3 three-dimensional morphology of polar terrestrial plants(3D MPP) 2016, 28 (2):  295-300.  DOI: 10.13679/j.jdyj.2016.2.295 Abstract ( 774 )   PDF (1268KB) ( 1016 )   Three-dimensional (3D) morphology is an important physiological characteristic of plants. In particular, because of its close link to the efficiency of photosynthesis, 3D morphology is an important tool for the investigation of plant growth. In 2014, 56 bryophyte specimens were collected near Great Wall Station on George King Island, Antarctica. The specimens were identified as four families, six genera, six species, and one variety. Representative samples were selected from each species and 3D morphology was determined using high precision laser scanning. The system harvested 120 million point cloud data points, as well as 987,429 points and 1,700,380 surfaces, to reconstruct the 3D morphological surfaces of seven plant species. In addition, Java Web technologies, MySQL, Three.js, and Tomcat, were used to build a domestic database (3D MPP, 3dmpp.gznu.edu.cn) of the 3D morphology of Antarctic plants, according to the WebGL standard with 3D rendering function. Using this database, researchers can browse and search for species information and can obtain access to the 3D morphological information. Furthermore, the database offers the option to download these 3D files in STL file format. The database offers a platform for the storage, display, and sharing of 3D morphological information of polar plants and provides basic data and tools for the comparative study of the 3D surface morphology of these plants. It also provides important protection for holographic information on polar plants. Related Articles | Metrics

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Progress in researvh on the acclimation of Antarctic marine diatoms to extreme environments Shuai Chunyan,Zhi Chongyuan 2016, 28 (2):  301-309.  DOI: 10.13679/j.jdyj.2016.2.301 Abstract ( 849 )   PDF (658KB) ( 1237 )   Antarctic marine diatoms form the basis of the Antarctic food web, and play a vital role in the Southern Ocean ecosystem. The acclimation of Antarctic marine diatoms to extreme environments is an ideal experimental scenario for the study of biological radiation resistance, cold resistance, and salt resistance. The last 30 years of domestic and international research on Antarctic marine diatoms was reviewed. There have been advances in research on the adaptation of diatoms in extreme environments to factors, including enhanced UV-B radiation, low temperatures, high salinity, and low light. Antarctic marine diatoms develop unique physiological, biochemical, genetic, and metabolic characteristics to adapt to extreme habitats. The findings of this paper provide an important reference for further research on the adaptation of Antarctic marine diatoms. Related Articles | Metrics