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31 March 2023, Volume 35 Issue 1 Previous Issue    Next Issue

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Identification and geological significance of magnetite quartzite in Vestfold Hills moraines, East Antarctica Wang Xiaohu, Wang Wei , Bao Hong, Liu Xiaochun , Hu Jianmin, Zhao Yue 2023, 35 (1):  1-14.  DOI: 10.13679/j.jdyj.20210077 Abstract ( 926 )   PDF (39597KB) ( 597 )   Because the Antarctic continent is covered by a permanent ice cap, its geology cannot be studied comprehensively. Moraines scattered around the glacier preserve substantial subglacial geological information, critical to understand the Antarctic geological and tectonic evolution. By studying moraines in the Vestfold Hills of east Antarctica, we identified two types of magnetite quartzite (banded iron formation, BIF); a light red, hematite-rich BIF, and a light gray BIF. The light red, hematite-rich BIF is mainly composed of magnetite, hematite, quartz, limonite, with small amounts of sericite and apatite. Quartz bands and magnetite bands are distributed alternately with nearly straight boundaries, whereas hematite is distributed in the edges or cracks of magnetite particles or in the quartz bands with a granular shape. The light gray BIF consists mainly of magnetite, hematite, quartz and limonite, with small amounts of diopside, tremolite, and actinolite. Quartz bands and magnetite bands are also distributed alternately, but the band edges are not straight. Hematite is distributed in the cracks of magnetite particles or in the quartz bands with a granular shape. Our analysis revealed that both BIFs formed in similar sedimentary environments. The samples may correspond to the Algoma type BIFs and the included hematite may result from early magnetite oxidation. We inferred that the environmental oxygen content was increasing when the hematite formed. Both Vestfold Hills samples likely formed 2.5 Ga, 3.0 Ga before present. Further study of BIF types in that region will improve our understanding of earth’s early geological and environmental evolution. Keywords  Antarctica, Vestfold Hills, magnetite quartzite, banded iron formation (BIF) References | Related Articles | Metrics

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Effects of warming on the denitrification in Antarctic lake sediments Cai Rui, Ma Hongmei, Wang Dongqi, Shi Guitao, Ren Mingcheng 2023, 35 (1):  15-23.  DOI: 10.13679/j.jdyj.20220002 Abstract ( 844 )   PDF (8411KB) ( 586 )   Global warming in the polar regions strongly influences the processes and rates of material cycling in the polar region ecosystems. In this study, the effects of global warming on the key process of nitrogen cycle processes in Antarctic lake sediments are reported. During the 29th Chinese National Antarctic Research Expedition, five lakes located near the Zhongshan Station were selected, one with sediments containing penguin manure (Mochou Lake) and four with natural lake sediments (Tuanjie Lake, Daming Lake, Mier Lake and Yuzhen Lake). The “sample-bottle mud constant-temperature mud culture method” was used to simulate temperature increases. Culture experiments were set at low temperature (1℃), medium temperature (5℃) and high temperature (11℃).  Results showed that the denitrification rate and denitrification potential of Mochou Lake sediments at low temperature were significantly higher (277.37 times and 246.73 times, respectively) than those of natural lake sediments. Limitted warming enhanced the sediment denitrification rate and potential, but excessive temperature increase inhibited the denitrification in some samples. At high temperature, the average denitrification rate of natural lake sediments under high temperature was 1.57 times and 3.56 times higher than at medium and low temperature, respectively, while the denitrification potential represented 1.91 times and 6.31 times the medium and low-temperature rates, respectively. For Mochou Lake sediments at high temperature, the denitrification rate was 1.78 and 2.07 time higher, and the denitrification potential was 0.72 and 1.01 times higher, respectively, than at medium and low temperature. Although the warming-induced relative increase in denitrification rate and denitrification potential was higher for natural lake sediments than for the Mochou Lake sediments, the absolute increase was higher at Mochou Lake. Higher contents of nitrate, ammonium salt, phosphate and organic carbon in penguin manure explain this high denitrification rate. Under global warming conditions, exogenous nitrogen input from penguins accelerates the nitrogen cycle in Antarctic lake sediments. References | Related Articles | Metrics

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Predicting bathymetry of the Amundsen Sea in Antarctica using the Gravity Geologic Method Yuan Hanxiao, Wang Yongkang, Li Jie, Zhang Huayi, Tang Qiuhua 2023, 35 (1):  24-33.  DOI: 10.13679/j.jdyj.20210092 Abstract ( 739 )   PDF (7460KB) ( 441 )   In this study, the submarine topography of the Amundsen Sea in Antarctica was inverted at 1'×1' resolution using the Gravity Geologic Method (GGM), shipboard single-beam echosounding data and altimeter-derived gravity anomaly data, version V30.1, from the Scripps Institution of Oceanography model, as input. First, an accuracy analysis confirmed that the GGM-based model yielded the highest overall accuracy, compared with other universal bathymetric models. Then, the influence of the number of control points and of the topographic relief on inversion accuracy was analyzed. Results showed that topographic relief strongly influenced inversion accuracy and that increasing the number of control points improved the inversion accuracy. Finally, the research area was partitioned by depth to analyze the relationship between density contrast and external factors. Density contrast was markedly influenced by topographic relief, thus the GGM was used in this study to calculate local interval partitioning depending on the optimal density contrast depth. Compared with global optimal density contrast inversion of seafloor topography, the method used in this study showed considerably higher accuracy. References | Related Articles | Metrics

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A statistical-dynamical joint model for seasonal prediction of Antarctic summer sea ice Wang Hui, Li Shuanglin, Liu Na 2023, 35 (1):  34-45.  DOI: 10.13679/j.jdyj.20210080 Abstract ( 845 )   PDF (2440KB) ( 871 )   To model summer sea ice in Antarctica, three predictors are selected: (1) sea surface temperature prediction in the Southern Ocean (40°S–80°S) from the Climate Forecast System version 2 (CFSv2), (2) observed sea surface temperature around the Maritime Continent (100°E–130°E, 10°N–15°S) in early austral spring; (3) observed sea level pressure in the southern extratropics (20°S–90°S) in early austral spring. In this study, the singular value decomposition method is used to extract relevant information, then a regression model is applied to predict the sea ice field. When applied retrospectively to simulations for 1983–2018, this model yields significantly improved results compared with raw CFSv2 predictions: temporal correlation between predicted sea ice concentrations at single grid points and observations is significant, with an average value of 0.76 over the Southern Ocean. From cross-validation results, prediction results are significantly better than those of CFSv2, with predicted sea ice extent significantly improved relatively to CFSv2 and to persistence prediction. These results indicate that the prediction performance of the joint statistical-dynamical model described in this study is high. Therefore, this model is important to predict Antarctic sea ice, for example when planning scientific survey activities in Antarctica. References | Related Articles | Metrics

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Accuracy evaluation of Arctic sea ice area and edge line from Fengyun-3D microwave data Yang Zijian, Wang Zemin, Liu Tingting 2023, 35 (1):  46-58.  DOI: 10.13679/j.jdyj.20210093 Abstract ( 816 )   PDF (1905KB) ( 1003 )   The microwave radiation imager (MWRI) aboard the Fengyun-3D satellite passively acquires microwave data, from which the area and edge line of Arctic sea ice are derived. MWRI data have seldom been used in related scientific studies, therefore their accuracy has not been sufficiently evaluated. This study combines sea ice concentration (SIC) results from six MWRI data processing algorithms to extract Arctic sea ice area and edge line, which are compared with results from the special sensor microwave imager/sounder (SSMIS) system and from the advanced microwave scanning radiometer 2 (AMSR2). Then, the SIC product derived from merged Moderate Resolution Imaging Spectrometer (MODIS) and AMSR2 observations (from 26 August 2019 to 31 December 2019, aboard NASA Terra and Aqua satellite) is used to evaluate MWRI data accuracy. The temporal variation trend of MWRI sea ice area is consistent with that of the merged MODIS-AMSR2 product. The sea ice edge line extracted from MWRI data is in better agreement with the merged MODIS-AMSR2 SIC product, with a root mean square error of 20~30 km, than with the SSMIS product. These differences are mainly caused by spatio-temporal resolution discrepancies between the datasets. In conclusion, the MWRI shows better performance than comparable instruments and is best suited for Arctic sea ice research and monitoring. References | Related Articles | Metrics

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The structure of zooplankton community and its sensitivity to environmental factors around the South Shetland Islands in summer of 2016/2017 Wang Junjian, Zhang Ye, Wang Yanqing, Yang Guang 2023, 35 (1):  59-71.  DOI: 10.13679/j.jdyj.20210096 Abstract ( 739 )   PDF (2466KB) ( 758 )   The structure, abundance, and diversity of the zooplankton community and its sensitivity to environmental factors in the seawaters of the South Shetland Islands, from late 2016 to early 2017, were analyzed. Twenty-four species of zooplankton were detected. The total abundance was 1095.51 ind∙m−3. The most abundant zooplankton were Euphausia superba, Calanoides acutus, Oithona similis and Salpa thompsoni. Their distribution was positively correlated with surface temperature. Conversely, the Shannon-Wiener and Pielou indices were negatively correlated with surface temperature. This shows that the strong recent warming of West Antarctic waters promotes the growth of common zooplankton in the South Shetland Islands seawaters in summer, but probably causes a decrease in the evenness and diversity of the zooplankton community. This study investigated the zooplankton distribution in important fishing grounds for Euphausia superba, providing fundamental information to understand the formation of krill fishing grounds. References | Related Articles | Metrics

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Wave risk analysis for oceanographic survey in Cosmonaut Sea, Antarctica Cao Lei, Wang Zike, Meng Fanchao, Guo Canwen, Zhao Longfei 2023, 35 (1):  72-82.  DOI: 10.13679/j.jdyj.20220420 Abstract ( 784 )   PDF (7020KB) ( 513 )   Risk analysis of wave events is an important means of ensuring the safety of oceanographic surveys. Previous wave risk studies mainly focused on coastal ocean engineering, essentially calculating the return period using extreme-value statistics. This method is not applicable to oceanographic surveys because of wave adaptability differences. This study proposes a new model to analyze wave event risks for oceanographic surveys. The model comprehensively considered the specific vulnerabilities of oceanographic survey activities, as well as wave event hazards. An index system was designed to hierarchize the hazards and an analytical method was established to identify vulnerabilities of oceanographic surveys. Wave risk level patterns were drawn from the model results. The method was evaluated in the Southern Ocean. Results showed that the proposed model effectively assessed the risk of wave events and provided crucial information for the design of oceanographic survey stations and the selection of operation periods and ship routes References | Related Articles | Metrics

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The background, development and enlightenment of the Madrid Protocol Ma Jinduo 2023, 35 (1):  95-108.  DOI: 10.13679/j.jdyj.20210088 Abstract ( 855 )   PDF (380KB) ( 1078 )   The historical background, negotiation process and recent development of the Protocol on Environmental Protection to the Antarctic Treaty (hereafter Madrid Protocol) reflect the change of status of environmental protection for international Antarctic governance, from nonexistent to marginal to central. Initially focused on resource utilization, with the Convention on the Regulation of Antarctic Mineral Resources Activities, the core governance concept for Antarctic Treaty Consultative Parties has shifted to environmental protection, with the Madrid Protocol. After six years of informal and personal diplomatic negotiations, the Convention on the Regulation of Antarctic Mineral Resources Activities was adopted in 1988 but not immediately implemented, because of partial reservations from United Nations countries and opposition from environmental organizations or Non-Consultative Parties. In 1991, the Madrid Protocol was adopted, prohibiting Antarctic mineral resource exploitation and establishing an environmental protection policy within the Antarctic Treaty System. In 2005, Annex Ⅵ to the Madrid Protocol was adopted, establishing the legal responsibility of the Parties to guarantee environmental protection while raising the bar for scientific research in Antarctica, but it has not yet taken effect. Environmental protection is currently both a key objective and the core issue for international governance of Antarctica. As an Antarctic Treaty Consultative Party with a strong scientific research capacity, China needs to fulfill its obligations under the Madrid Protocol by introducing specific legislation for Antarctic environmental protection. On the basis of its operational capacity and Antarctic research programs, China should also use its Consultative Party status and rights to actively participate in Antarctic governance, expand its substantial presence and preserve its interests in Antarctica, while collaborating to improve the Antarctic environmental protection system. Keywords  the Madrid Protocol, the Convention on the Regulation of Antarctic Mineral Resource, Antarctic environmental protection References | Related Articles | Metrics

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U.S. think tanks’ perception and suggestion of China’s Arctic policies and activities since 2018 Wu Qihang 2023, 35 (1):  109-123.  DOI: 10.13679/j.jdyj.20210082 Abstract ( 827 )   PDF (488KB) ( 1055 )   In the current competitive context between China and the United States of America (hereafter U.S.), the importance of Arctic-related issues for the U.S. government has markedly increased. Therefore, such issues have become a focus point for prominent U.S. think tanks. Understanding the think tanks’ perception of China’s Arctic policy and their possible suggestions to the U.S. government could allow China to understand U.S. policy toward China in the Arctic. Ten representative reports from five major U.S. think tanks were selected as a research sample; seven reports from four non-U.S. think tanks were used for a broader perspective. The research sample indicates that U.S. think tanks have conducted comprehensive discussions on the influence and purpose of China’s Arctic activities, with a focus on Sino-Russian Arctic cooperation. Our analysis shows a consensus among the U.S. think tanks that China is pursuing a long-term policy in the Arctic. The reports also emphasize that China is using economic and scientific means to expand its physical presence and strategic influence in the Arctic region. Global evaluation of China’s Arctic policy by the U.S. think tanks was negative. Furthermore, they suggested four countermeasures to the U.S. government in response to China’s Arctic policies and activities: containing China economically, strengthening the U.S. Arctic presence and intervention capacity, dividing China and Russia, and reshaping the alliance in the Arctic. References | Related Articles | Metrics

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Overview on the thermodynamic and dynamic factors influencing Arctic sea ice thickness Wang Yun, Li Xuewei, Wang Jinfei, Yu Lejiang, Yang Qinghua 2023, 35 (1):  124-138.  DOI: 10.13679/j.jdyj.20210051 Abstract ( 909 )   PDF (373KB) ( 1234 )   Under current climate change conditions, Arctic sea ice has become a key scientific topic, because of its close connection with global climate. Sea ice thickness, important for material and energy exchanges between the atmosphere, sea ice and oceans, is also an indicator of climate change. In the last 40 years, Arctic sea ice cover has rapidly shrunk, ice thickness has markedly decreased, and ice melt has strongly accelerated. These changes have markedly affected the climate system at the regional and global scale. Summarizing previous research results, this paper comprehensively describes the thermodynamic and dynamic processes affecting Arctic sea ice thickness. Thermodynamically, sea ice thickness is affected by atmospheric variables including ice characteristics, air temperature, water vapor, rainfall, snowfall and cloud cover, through the sea ice surface radiation budget and turbulent heat exchange (sensible and latent heat). Moreover, the ocean heat flux affecting sea ice thickness results from upper ocean heating by solar radiation, vertical mixing induced by wind stress, and warm water input from middle and low latitudes. Dynamically, the interaction between wind stress and ocean currents generates sea ice transport and deformation, thereby affecting the sea ice thickness. In summary, climate variability induces additive forcing from these thermodynamic and dynamic processes on sea ice thickness variation. References | Related Articles | Metrics

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Process in the study of ice cover and snow surface energy balance in the Arctic Zou Xiaowei, Yang Diyi, Tian Biao, Zhang Lei, Sun Weijun, Li Zhao, Ding Minghu 2023, 35 (1):  139-151.  DOI: 10.13679/j.jdyj.20220001 Abstract ( 689 )   PDF (1665KB) ( 1288 )   Land-atmosphere interaction processes, especially glacier/snow surface albedo variations, are key scientific issues that restrict the understanding of rapidly changes (e.g., surface temperature rising, sea ice and snow extent decreasing) in the Arctic. This study, on the basis of recent improvements of observation techniques and analysis methods, shows the marked progress achieved in characterizing the Arctic glacier/snow surface energy balance. However, due to lack of the observation data with high quality, the robustness of the parameterization schemes and dataset with remote sensing/numerical models should be further evaluated. Therefore, longer time series of comprehensive observations, at more numerous and densely distributed observation sites, are needed for future surface energy balance studies. In addition, multi-source satellite remote sensing monitoring systems should be developed to acquire large scale, three-dimensional, dynamic, and continuous datasets, for evaluation and validation of remote sensing products and complex parameterization schemes. Such data will also allow for better characterization of the mechanisms influencing the Arctic glacier/snow surface energy balance and of sea ice/snow/atmosphere interactions, thus representing an important contribution to polar cryosphere and climate change research. References | Related Articles | Metrics

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Exploration and research on towing operation in polar ice area Xia Yinyue, Chen Qingman, Zhu Bing, Ding Feng, Shen Yue, Liao Zhouxin, Pei Jiahao, Chen Jiyu 2023, 35 (1):  152-159.  DOI: 10.13679/j.jdyj.20210097 Abstract ( 738 )   PDF (1098KB) ( 879 )   As key areas occupying a strategic position and with a strong influence on the global climate system, the polar seas have become the object of an increasing number of scientific studies. Towing is an important method for marine surveys. In polar ice areas, towing operations are often affected by the weather and the sea ice cover, and they depend on type of survey equipment. Therefore, unpredictable problems encountered during towing operations often prevent the successful implementation of planned survey tasks. On the basis of yearly field operation reports from the regular Chinese polar expeditions, this study summarizes the risks and problems of towing operations in polar ice areas, provides a comprehensive analysis and discussion, and suggests targeted measures to optimize towing operations, as a reference for future towing survey operations in polar ice areas. References | Related Articles | Metrics

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Analysis of the medical data of the members of the 12th Chinese National Arctic Research Expedition Hao Junjie , Chen Jian 2023, 35 (1):  160-165.  DOI: 10.13679/j.jdyj.20220441 Abstract ( 716 )   PDF (919KB) ( 753 )   In order to improve the level of medical security and rescue during the polar cruises, and put forward/upgrade the corresponding medical prevention and treatment suggestions, the medical data of the members of the 12th Chinese National Arctic Research Expedition onboard the icebreaker R/V Xulong 2 were collected and analyzed. The constituent ratio and the number of the expedition members who were injured or ill and went to the doctor were counted; the constituent ratio and the number of the diseases and injuries of the expedition members were counted; the constituent ratio and the number of the diseases and injuries of various systems were counted; the possible inducing factors of common diseases and injuries were analyzed. The study found that during the 79-day voyage (from 12 July to 28 September 2021), 76 (76.0%) of the 100 expedition members were injured or ill and went to the doctor; 143 person-times of the patients were made a diagnosis and given treatment (not including further consultation), the first ten diseases and injuries were skin injury, pharyngitis (tied first), soft tissue injury, gastritis, upper respiratory tract infection, chapped or peeling hands and feet, insomnia, dental ulcer, asthenopia, gout, dermatophytosis (tied for tenth). According to the physiological system of the human body, the diseases and injuries were trauma and bone and joint diseases, dermatological diseases, ear nose throat diseases, digestive diseases, respiratory diseases, stomatological diseases, ophthalmic diseases, neuropsychological diseases, metabolic and endocrine diseases, cardiovascular diseases, urogenital diseases. Therefore, it is suggested to take measures such as safety and health education, strengthening safety protection, strict implementation of operation specifications, improving team doctor skills and strengthening telemedicine. References | Related Articles | Metrics