Chinese Journal of Polar Research

Studies on polar non-sea-salt sulfate (nssSO₄^2– ) and methanesulfonate(MSA) and their environmental indications

Ma Hongmei, Sun Bo, Hu Zhengyi, Shi Guitao

2021, 33 (2): 171-182. DOI: 10.13679/j.jdyj.20200033

Abstract ( 1018 )

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The main sulfur compounds of polar aerosols and snow-ice media are nssSO₄²⁻ and MSA. Spatially, nssSO₄²⁻ and MSA have obvious latitude effect characteristics. Temporally, nssSO₄²⁻ and MSA have interannual variation characteristics (high in summer and low in winter). The concentrations of nssSO₄²⁻and MSA in Antarctica ice cores increased during glacial periods, whereas the MSA concentration of Arctic ice cores decreased during glacial periods, although the nssSO₄²⁻ concentration still increases during glacial periods. Both nssSO₄²⁻ and MSA can be used to infer climate and environmental information such as marine primary productivity,atmospheric temperature, changes in sea ice extent and human influence. The prospect of using nssSO₄²⁻ and MSA to study global change is also discussed.

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Mesoproterozoic–early Paleozoic geological events in the Pinjarra Orogen (Western Australia) and their correlations with geological events in the Rayner Orogen (East Antarctica)

Yu Shihang, Chen Longyao, Liu Xiaochun

2021, 33 (2): 183-197. DOI: 10. 13679/j.jdyj.20200035

Abstract ( 900 )

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The Pinjarra Orogen at the western margin of West Australia has experienced Grenvillian and Pan-African high-grade metamorphism. The tectonic evolution of the orogen is closely related to the amalgamation and breakup of the supercontinent Rodinia and the subsequent formation of the supercontinent Gondwana. This paper summarizes and reviews three major geological events of the Pinjarra Orogen during the Mesoproterozoic–early Paleozoic and discusses their correlations with geological events in the Rayner Orogen of East Antarctica. The three major geological events in the Pinjarra Orogen include: (1) a late Mesoproterozoic magmatic/metamorphic event (1090–1020 Ma), which is related to the global Grenvillian Orogeny with a controversial detailed tectonic setting; (2) a mid-Neoproterozoic magmatic event (780–660 Ma), which has attributes of extension/rifting magmatism and is probably related to the breakup of Rodinia; (3) a late Neoproterozoic–early Paleozoic (i.e., Pan-African) geological event (540–520 Ma), which is related to the assembly of East Gondwana. Comparative studies show some differences in the Mesoproterozoic–early Paleozoic geological events between the Pinjarra Orogen and the Rayner Orogen, indicating that these two belts could not have been directly connected into a unified Grenvillian orogenic belt. The Pinjarra Orogen and the intensively reworked Rayner Orogen in Prydz Bay (i.e., the Prydz Belt) underwent a similar late Neoproterozoic–early Paleozoic orogenic event, implying a certain relationship between them. However, the absence of a mid-Neoproterozoic magmatic event in Prydz Bay suggests that these two belts also could not have been directly connected. Therefore, the continuation of the Pinjarra Orogen into East Antarctica still remains controversial, and further investigation into this issue is required.

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Historical changes in organic matter sources and ecological environment indicated by sedimentary lipid biomarkers in a West Antarctic lake

Guo Xiaoze, Zhao Jun, Han Zhengbing, Li Dong, Zhang Haifeng, Sun Weiping, Hu Chuanyu, Pan Jianming

2021, 33 (2): 198-208. DOI: 10. 13679/j.jdyj.20200042

Abstract ( 793 )

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Based on 210Pb dating of XH1 core sediment samples from Xihu Lake on King George Island, Antarctica, a centennial (1885-2006) sedimentary stratigraphic sequence was established. The lipid biomarkers, such as n-alkanes, fatty acids and sterols, were quantitatively analysed. The characteristics of their molecular assemblages and large-scale climate events (El Ni?o-Southern Oscillation (ENSO) and Southern Hemisphere Annular Mode (SAM)) were synthetically studied. The source of organic matter, sedimentary environment, early diagenesis and their relationship with the changes in ecological environment were discussed. The results showed that the main peak carbon (nC23) of n-alkanes, the latter main peak carbon (C24:0) of fatty acids, the higher content of C29 sterols and the lower ratio of C21–/C22+ indicated that the main source of organic matter in sediment of Xihu Lake was lower terrestrial plants such as mosses and lichens, while the contribution of aquatic plants and microorganisms was relatively minor. The ratio of C18:2/C18:0 of fatty acids indicated that, on the interdecadal time scale, SAM rather than ENSO, may have significant influence on the ecosystems of Antarctic Peninsula, and the impact of SAM on aquatic organisms in lakes is more obvious than that on terrestrial plants. ACI, an autochthonous contribution index of sterols, showed that when the westerly wind weakened and the Antarctic Peninsula warmed, the organic matter contributed by aquatic organisms decreased. Overall, in the past 100 years, the Xihu Lake was in a weakly oxidized sedimentary condition, with weak early diagenesis, and the impact of large-scale climate events on the lake sedimentary environment was weak.

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Parameter estimation of the melt pond parameterization scheme of a sea ice model using an adjoint model

Lu Yang, Wang Xiaochun

2021, 33 (2): 209-221. DOI: 10.13679/j.jdyj.20200044

Abstract ( 902 )

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Melt ponds can significantly affect Arctic sea ice. However, in the widely used sea ice model CICE6.0, large differences still exist between simulation and observation in terms of melt pond fraction. The CESM melt pond parameterization scheme in CICE6.0 can calculate the volume, area fraction and depth of melt ponds.However, the scheme has some uncertain parameters, which can affect melt pond simulation. These parameters could be determined through parameter estimation, which requires a large amount of sensitivity simulations. An adjoint model can efficiently calculate parameter sensitivity. In this work, an adjoint model was developed for the CESM melt pond scheme through a forward model code transformation method. The adjoint model was checked following the standard method of adjoint model development. A melt pond parameter estimation algorithm was also developed, which is composed of the CICE6.0 sea ice model, melt pond adjoint model, and L-BFGS minimization algorithm. The parameter estimation algorithm was further verified under ideal conditions. By using the developed parameter estimation algorithm and MODIS satellite melt pond fraction observation data as the observational constraints, the melt pond aspect ratio parameter in the CESM scheme was estimated in several time periods during summer and for two different regions in the Arctic. One region was for first-year ice, and the other multi-year ice. The estimated parameter values were used in later simulation, and the output values were compared with the simulation using the default parameter. The results show that the estimated parameter values were quite different for multi-year ice and first-year ice and also varied with time. This is quite different from the default constant value of the parameter used in CICE6.0. The estimated parameter values were found to be more appropriate for melt pond simulation. The simulation error of the melt pond fraction was reduced. The simulated melt pond fraction was more consistent with MODIS observations than that using the default parameter.

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Characterisitic analysis of vertical structure of lower atmosphere over the Arctic Ocean during CHINARE 2018

Tian Zhongxiang, Zhao Fu, Yin Zhaohui, Yu Wenhao

2021, 33 (2): 222-230. DOI: 10. 13679/j.jdyj.20200039

Abstract ( 743 )

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Using the radiosonde data obtained during the 9th Chinese National Arctic Research Expedition (CHINARE 2018), the atmospheric structure characteristics over the Arctic Ocean during the observation period were analyzed. The results show that: (1) The average of temperature lapse rate in the middle troposphere was 5.67°C·km⁻¹, which was consistent with that over the central Arctic. The characteristics of high-level jets were remarkable, especially over the high latitude region. (2) The medians of the height of the boundary layer temperature inversion base, the depth of the inversion and the temperature change through the inversion were 306 m, 299 m and 3.2°C, respectively, which were consistent with SHEBA(Surface Heat Budget of the Arctic Ocean). (3) The medians of the height of the low-level jet core and the wind speed in the core were 456 m and 11.40 m·s⁻¹, respectively, and the wind speed of the jets was mostly distributed within 6–14 m·s⁻¹. (4) Only 67.27% of the low-level jets were below the lowest inversions. However, considering multiple temperature inversion layers, 92.73% of the low-level jets were beneath the top of the inversions.

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Identification and phenotypic characterization of an Arctic marine bacterium grown on Dimethylsulfoniopropionate

Zhang Yihe, Zeng Yinxin, Qu Jiangyong

2021, 33 (2): 231-240. DOI: 10. 13679/j.jdyj.20200037

Abstract ( 742 )

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Dimethylsulfoniopropionate (DMSP) is a highly abundant sulfur-containing compound in marine environments. It is mainly produced by marine phytoplankton, and can act as a key nutrient for marine microorganisms. Strain DMSP-1 was isolated from Arctic seawater of Kongsfjorden using a selective growth medium. Based on the 16SrRNA gene sequence and genomic ANI (Average Nucleotide Identity) analyses, the bacterium was classified and identified as the species Pseudomonas lactis. The bacterial cells were rods with polar flagella. The strain was psychrotrophic (growing well between 22 and 29°C with an upper temperature limit at 38°C) and halotrophic (growing well between 0 and 4% NaCl with an upper salinity limit at 8% NaCl), indicating adaptation to the local habitat. A carbon source for growth experiment confirmed that strain DMSP-1 could grow with DMSP as the sole carbon source. The bacterium showed many genotypic characteristics similar to the type strain Pseudomonas lactis WS 4992^T. At the same time, in contrast with P. lactis WS 4992^T, strain DMSP-1 showed tryptophan deaminase and urease activity, and was unable to produce acid from rhamnose. Further research on Pseudomonas sp. DMSP-1 will provide deep insight into the mechanism of marine bacteria degrading DMSP and their ecological functions in the Arctic marine environment.

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Diversity of cultivable epiphytic bacteria of Polysiphonia algae from Ny-Ålesund, Svaldbard, Arctic

Sun Xiaomeng, Fan Shoujin

2021, 33 (2): 241-249. DOI: 10. 13679/j.jdyj.20200045

Abstract ( 714 )

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To analyze the diversity of epiphytic bacteria in Arctic algae, a red algae sample (Polysiphonia sp.) was collected from Ny-Ålesund, Svaldbard, Arctic in July 2019. A total of 60 cultivable strains of epiphytic bacteria were isolated from the sample using the dilution plating method. Analysis of 16S rRNA gene sequences revealed that the isolated strains mainly belonged to the class γ-Proteobacteria (39 strains, 65% of the total strains isolated from the red algae samples), followed by the classes Actinobacteria (10 strains, 17%), Flavobacteriia (eight strains, 13%), α-Proteobacteria (two strains, 3%) and Bacilli (one strain, 2%). The strains were affiliated with 12 genera with the predominant genera being Psychrobacter (22 strains, 37%) and Pseudoalteromonas (12 strains, 20%). The results preliminarily illustrate the diversity of cultivable epiphytic bacteria in Arctic red algae (Polysiphonia sp.), laying a foundation for studies on the ecological functions and exploitation of these particular Arctic microbial resources.

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Comparison and analysis of the accuracy of two new Antarctic DEMs based on remote sensing images

Geng Tong, Xiao Feng, Zhang Shengkai, Li Jiaxing, Xuan Yue, Li Fei

2021, 33 (2): 250-259. DOI: 10. 13679/j.jdyj.20200031

Abstract ( 911 )

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The Reference Elevation Model of Antarctica (REMA) and TanDEM-X DEM are two internationally released high-resolution DEMs based on remote sensing images. Cryosat-2 satellite altimetry data and IceBridge airborne altimetry data were used to verify and compare the accuracy of the two DEMs for the Antarctic ice sheet,considering factors such as radar signal penetration and slope. The results show that within the range of the Antarctic ice sheet, compared with CryoSat-2 data, the mean elevation difference of REMA was −0.742 m, the standard deviation was 5.269 m, the mean elevation difference of the TanDEM-X DEM was 2.946 m, and the standard deviation was 5.755 m. The difference in elevation between the TanDEM-X DEM and IceBridge data in the inland area of Antarctica was slightly smaller than the difference in elevation at the edge of the ice sheet. The overall difference in elevation was more obvious than that between the REMA and IceBridge data. The elevation values of REMA were slightly higher than those of the TanDEM-X DEM. The mean elevation difference between the two DEMs was 3.742 m, and the standard deviation was 2.807 m. This was related to the penetration of the snow source of the TanDEM-X DEM data source based on X-band radar waves.

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Design and implementation of surface water sampling system of Xuelong 2

Yuan Dongfang, Wang Shuoren, Chen Qingman, Liu Zhibing, Liao Zhouxin, Xia Yinyue

2021, 33 (2): 260-267. DOI: 10. 13679/j.jdyj.20200038

Abstract ( 842 )

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The surface seawater sampling system is a basic component of scientific research equipment on a scientific research vessel, providing continuous surface seawater sampling for instruments such as FerryBox, laboratory instruments and incubators. It can provide continuous monitoring of pCO₂, pH, dissolved oxygen, temperature, salinity, chlorophyll, turbidity, nutrients (NH₄⁺, NO₂⁻, NO₃⁻, PO₄³⁻ and SiO₃²⁻) and methane in surface seawater. To obtain accurate data, a real-time, high-fidelity and continuous surface sea water supply is needed for monitoring and research. Because of the particularity of the operation area, the sampling system faces common problems in polar regions; for example, the suction mouth is often blocked by broken ice in the pack-ice zone, marine organisms adhere to the pipeline wall and cause pollution, the seawater temperature rises rapidly during transportation, and pipeline rust contaminates seawater samples. To solve the above problems, the Xuelong 2 was designed with regard to several key points such as anti-icing, high-fidelity seawater sampling, real-time collection, and prevention of biological pollution. We successfully designed a surface seawater sampling system that can operate continuously in the pack-ice zone during the 36^th CHINARE (Chinese National Antarctic Research Expedition), markedly reduce the occurrence of ice blockage with a high probability, and obtain a large amount of valuable data for scientific research.

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Research on national relations network of Arctic route system

Ding Chaojun, Li Zhenfu, Shi Xiaomei, Chen Xue

2021, 33 (2): 268-278. DOI: 10. 13679/j.jdyj.20200047

Abstract ( 773 )

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With the melting of Arctic sea ice, the considerable strategic value of the Arctic route has attracted the attention of many countries, and the geopolitical issue of the Arctic route will become an important part of international geopolitics in the future. This paper quantitatively evaluates the evolution of the structural characteristics of the national relationship network under the influence of the Arctic routes from 2007 to 2019 by constructing a national relationship network of the Arctic route system, and estimates the geopolitical power characteristics of each country. The results show that the scale of national relations networks continues to expand, and the network density shows a trend of first rising and then decreasing. Based on analysis of each sub-network, the network densities of the scientific research cooperation network and the environmental protection cooperation network are the largest, the network densities of the energy cooperation network and the shipping cooperation network are on the rise, and the security cooperation network density has been low. In addition, the network has a small cosmopolitan nature, and the scale-free feature becomes more obvious during the evolution process. Analysis of the characteristics of specific nodes indicates that the eight Arctic countries are important nodes in the network. During the evolution process, the importance of countries outside the Arctic has increased. Moreover, the communities are divided. In the evolution process, the eight Arctic countries have evolved from convergence to differentiation, and the national relations in the network have become more complex.

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Risk evaluation of different legs of Northeast Arctic route based on fuzzy analytic hierarchy process—multilevel extension

He Peilong, Ma Xiaoxue, Zhang Jingwen, Qiao Weiliang

2021, 33 (2): 279-293. DOI: 10. 13679/j.jdyj.20200016

Abstract ( 743 )

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The Northeast Arctic route has a long span, and the geographical environment of the sea area is complex. Under the influence of the natural environment and human intervention, there are great differences in the navigation environments of different legs of this route. Analysis of the differences between different legs is of great significance to ensure navigation safety. The fuzzy analytic hierarchy process method and multi-level extension theory were combined to evaluate and analyze the risk levels of different legs of the Northeast Arctic route based on the risk evaluation index system of the Northeast Arctic route. The results show that (1) ice conditions, temperature, visibility, channel conditions, and navigation support capabilities are the five most important factors affecting navigation risks along the Northeast Arctic route; (2) there are obvious differences in the safety risks of each leg, and the risk level of most indicators for the East Siberian Sea–Delang Channel leg is relatively high; (3) the risk assessment results are basically consistent with the actual situation, which can provide an important reference for ensuring the safety of the Northeast Arctic route.

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Analysis on overview and hot spots of polar science based on bibliometrics

Chen Liulin, Kong Jia, Deng Sanhong, Shen Chenchen

2021, 33 (2): 294-306. DOI: 10. 13679/j.jdyj.20200040

Abstract ( 1003 )

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Scientific research in the polar region has become the focus of the world's major powers, because of the important role of the poles in the Earth’s climate system. This situation has given rise to continuously increasing investment in and scientific output about polar research in recent years. Scientific research on the polar regions is extensive, including astronomy, atmospheric science, marine science, geology, biology and other domains. Through bibliometric analysis, this study visualized the status of international polar research papers from 2015 to 2017 regarding publishing trends, the main publishing countries, publishing institutions, distribution of research fields, and research topics. This paper can provide a reference to clarify the status of polar investigation and research in China, help scientific research teams identify potential partners and technology owners, and yield enlightening suggestions for future Chinese polar research arrangements and international cooperation.

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Progress of the SCAR Action Group Bedmap 3 project

Cui Xiangbin

2021, 33 (2): 307-308.

Abstract ( 574 )

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