08 March 2017, Volume 28 Issue 1
    

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    Foreword
  • Chengsen Li, Hans‐Ulrich Peter, Qinghua Zhang, Zhengwang Zhang, Renbin Zhu
    Advances in Polar Science. 2017, 28(1): 0.
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    The impacts of global changes on the natural environment of the polar regions have been observed and investigated by scientists over recent decades. For example, the melting of glaciers and the changes induced in both the global carbon cycle and the freeze–thaw cycle of the polar regions due to global warming have exerted pressure on the polar environment. Furthermore, the warming climate, changes in hydrological conditions, and changes to the rates of methane and nitrous oxide production and respiration in different types of soil have also constituted a challenge to polar region ecosystems.

    Environmental changes in the polar regions, especially Antarctica, have been influenced by very few anthropogenic factors because of the remoteness of these areas. However, heavy metal elements, persistent organic pollutants, and organophosphorus esters have been found in polar regions following transportation via atmospheric and oceanic circulations, and even by human activity. All the effects related to both natural environmental changes and human activities are cumulative, doubling the challenges faced by the polar ecosystem.

    The polar environment ecosystem includes invertebrates, birds, mammals, algae, land plants, lichens, and microorganisms. The ecosystem response to polar environmental change includes the appearance of new species of microorganisms, alteration to the habits and population dynamics of plants and animals, and variation in biodiversity. Because of the minimal impact of human activity in polar regions, polar ecosystem response to environmental change is very significant for scientific research because polar life is recognized as a bioindicator of global change.

    Over recent decades, research scientists from around the world have paid increasing attention to the investigation and monitoring of environmental changes in polar regions. In particular, Chinese scientists have achieved considerable progress in the research fields of the polar atmosphere, oceans, glaciers, and marine life. We would like to gather and publish these results in this special issue of Advances in Polar Science. For this issue, we have two reviews and six articles contributed by Chinese researchers and their international collaborators.

    The first review focuses on Antarctic birds and mammals, i.e., penguins and seals, and it highlights the need for long-term, continuous monitoring and investigation to assess the impact of climate change on these species. Another one reports the discovery of organic pollutant organophosphorus esters on the Antarctic Ice Sheet. The first article reports the creation of 13 permanent plots on Fildes Peninsula, King George Island, Antarctica, which are used as a network for long-term monitoring of vegetation, including Deschampsia Antarctica (a native vascular plant), mosses, lichens, and microorganisms. This network is serving as a platform for multidisciplinary Antarctic research studies including botany, microbiology, ecology, and environmental science. After studies of diversity and population characteristics, the second and third articles address an important discovery that cultured fungi of the Arctic aquatic environment could be used as prototype drugs for medicinal proposes. The nucleotide differences of the mbf1 gene in the lichenized fungus Umbilicaria decussate from the Antarctic, Arctic Regions, and extra-polar Armenia were compared and the data obtained proven useful in further polar studies. The remaining three articles consider the serious situation of pollution in the polar regions as a warning. These important works highlights the influence of the temperature, nutrients, and moisture of soil in the High Arctic in summer on CO2 fluxes, ecosystem respiration, and net ecosystem exchange. The rates of methane and nitrous oxide production and respiration from different soils are also reported, and their relationships with the activity of the freeze–thaw cycle of the coastal Antarctic tundra are indicated. In the final article, studying heavy metal elements, two pre-treatment methods for mercury stable isotope analysis are introduced and their use with Antarctic moss demonstrated successfully.
  • Contents
  • Editorial Office of Advances in Polar Science
    Advances in Polar Science. 2017, 28(1): 0-0.
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  • Reviews
  • WU Fuxing, DONG Lu, ZHANG Yanyun, ZHANG Zhengwang
    Advances in Polar Science. 2017, 28(1): 1-12. https://doi.org/10.13679/j.advps.2017.1.00001
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    Birds and marine mammals in Antarctica, especially penguins and seals, are top consumers and critical elements of the Southern Ocean ecosystem. As a region undergoing rapid global change, new challenges will be posed to the survival of these vertebrates species. Global climate change causes many alterations, such as ocean temperature rise, altered sea ice distribution, and abnormal climate events along with effects of intensive human activities, such as fishing. These not only directly affect the spatiotemporal distributions and population dynamics of Antarctic birds and marine mammals but also indirectly influence them via modification of their food resources. At present, the impact of climate change on birds and marine mammals in the Antarctica is focusing on a number of species in a few areas. Response mechanisms of these species are still very limited and therefore require further long-term and continuous monitoring and research.

  • CHENG Wenhan, BLAIS Jules M., XIE Zhouqing, LIU Yi, LI Ming, SUN Liguang
    Advances in Polar Science. 2017, 28(1): 13-22. https://doi.org/10.13679/j.advps.2017.1.00013
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    Polar regions are free from major anthropogenic impact due to their remoteness. However, certain pollutants can be transported there via atmospheric and/or oceanic circulations. Here we present an overview of current research on organophosphorus esters (OPEs) in polar regions by reviewing the literature on distribution, source and transport of OPEs. Current research on OPEs reveals significant anthropogenic influences in both polar regions. As well as the expected occurrence in the Arctic, OPEs were found on the Antarctic Ice Sheet up to 650 km from the coast, and the OPE concentrations were higher at high elevation due to cold climate retention. The immediate source of OPEs for inland Antarctica might be the Southern Ocean surrounding the continent, where OPEs in aerosols and seawater showed comparable concentrations to remote areas in the European Arctic. A positive correlation between aerosol OPEs in the open water and the surface vortex of ocean currents indicates that these compounds may be transported and accumulated in the ocean currents. The Antarctica Circumpolar Current accumulates them in the marginal seas of Antarctica.

  • Articles
  • YAO Yifeng, WANG Xia, LI Jinfeng, YANG Jian, CAO Shunan, PENG Fang, KURBATOVA Ljuba, PETER Hans-Ulrich, BRAUN Christina, LI Chengsen
    Advances in Polar Science. 2017, 28(1): 23-28. https://doi.org/10.13679/j.advps.2017.1.00023
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    Climate warming has become evident in the maritime Antarctic over the past decades, and has already influenced the growing season and the population size of two native vascular plants in Antarctica, Deschampsia antarctica and Colobanthus quitensis. Both vascular plant species are therefore regarded as good bioindicators of regional warming in west Antarctica. To carry out long-term monitoring of vegetation (mainly using D. antarctica) and build a comprehensive research platform for multi-disciplinary study (including botany, microbiology, ecology, and environmental science) for Chinese scientists, 13 permanent plots were established in January and February of 2013–2015 in the area of Fildes Peninsula (King George Island). Here we present the benchmark data of the first observations from these plots, including site characteristics, and the population and associates of D. antarctica in each plot. The basic data are important to understand the vegetation change, distribution range, and expansion of D. antarctica in Antarctica under future climate change scenarios.

  • ZHANG Tao, ZHAO Lili, YU Caiyun, WEI Tao, YU Liyan
    Advances in Polar Science. 2017, 28(1): 29-42. https://doi.org/10.13679/j.advps.2017.1.00029
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    This study assessed the diversity and α-glycosidase inhibitory activity of cultured fungi isolated from four aquatic environments (stream, pond, glacial ice, and estuary) in the Ny-Ålesund region (Svalbard, Norway, High Arctic). A total of 134 fungal isolates were obtained from 13 water samples. Based on morphological characteristics and sequence analyses of the nuclear ribosomal DNA internal transcribed spacer region, these fungal isolates were identified as belonging to 47 species, with 26 belonging to the Ascomycota, 20 to the Basidiomycota, and one to the Zygomycota. The most frequently detected fungal species were Vishniacozyma sp. 2, Cadophora sp. 2, Phenoliferia sp. 1, Dioszegia sp. 2, and Mortierella sp.; these species occurred in 10, eight, seven, six, and five of the samples, respectively. Among the 134 fungal isolates, 17 isolates of 15 species displayed high α-glycosidase inhibitory activity in culture. The results suggest that diverse and distinct populations of cultured fungi are present in Arctic aquatic environments, and they include taxa that are potential sources of bioactive molecules that may be used as prototype drugs for medicinal proposals.

  • WANG Yanyan, LIU Rundong, WANG Weicheng, WEI Xinli, WEI Jiangchun
    Advances in Polar Science. 2017, 28(1): 43-49. https://doi.org/10.13679/j.advps.2017.1.00043
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    Multiprotein bridging factor 1 (MBF1) is a transcriptional co-activator related to stress tolerance in various organisms. We investigated the nucleotide differences in the mbf1 gene in the lichen-forming fungus Umbilicaria decussata collected from polar (i.e., Antarctica and the Arctic) and non-polar (i.e., Armenia) regions. The 552-bp Udmbf1 genes isolated from eight samples contained numerous sequence variations, including single nucleotide polymorphisms as well as insertions and deletions. The frequency of nucleotide changes was higher in the intron than in the coding sequence. The nucleotide polymorphism levels (π=0.01792, θ=0.01792) and haplotype diversity (Hd=1) in the Udmbf1 gene from Antarctic samples were relatively high. Additionally, of the 19 detected nucleotide sequence variation sites, 15 were observed only in Antarctic samples. The resulting amino acid changes occurred in the N-terminal, whose function remains unknown. Although these DNA polymorphisms and amino acid changes have been verified in Antarctic samples of U. decussata, there is still little evidence indicating that different environmental conditions affected the functional evolution of Udmbf1. Additional studies involving more U. decussata samples from representative ecotypes will be necessary to uncover the relationships among DNA polymorphisms, functional gene evolution, and lichen habitats.

  • LI Fangfang, ZHU Renbin, BAO Tao, WANG Qing, XU Hua
    Advances in Polar Science. 2017, 28(1): 50-60. https://doi.org/10.13679/j.advps.2017.1.00050
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    The Arctic ecosystem, especially High Arctic tundra, plays a unique role in the global carbon cycle because of amplified warming in the region. However, relatively little research has been conducted in High Arctic tundra compared with other global ecosystems. In the present work, summertime net ecosystem exchange (NEE), ecosystem respiration (ER), and photosynthesis were investigated at six tundra sites (DM1–DM6) on Ny-Ålesund in the High Arctic. NEE at the tundra sites varied between a weak sink and strong source (−3.3 to 19.0 mg CO2∙m-2∙h-1). ER and gross photosynthesis were 42.8 to 92.9 mg CO2∙m-2∙h-1 and 54.7 to 108.7 mg CO2∙m-2∙h-1, respectively. The NEE variations showed a significant correlation with photosynthesis rates, whereas no significant correlation was found with ecosystem respiration, indicating that NEE variations across the region were controlled by differences in net uptake of CO2 owing to photosynthesis, rather than by variations in ER. A Q10 value of 1.80 indicated weak temperature sensitivity of tundra ER and its response to future global warming. NEE and gross photosynthesis also showed relatively strong correlations with C/N ratio. The tundra ER, NEE, and gross photosynthesis showed variations over slightly waterlogged wetland tundra, mesic and dry tundra. Overall, soil temperature, nutrients and moisture can be key effects on CO2 fluxes, ecosystem respiration, and NEE in the High Arctic.

  • LIU Yashu, ZHANG Wanying, ZHU Renbin, XU Hua
    Advances in Polar Science. 2017, 28(1): 61-74. https://doi.org/10.13679/j.advps.2017.1.00061
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    In coastal Antarctica, frequent freezing–thawing cycles (FTCs) and changes to the hydrological conditions may affect methane (CH4) and nitrous oxide (N2O) production and respiration rates in tundra soils, which are difficult to observe in situ. Tundra soils including ornithogenic tundra soil (OAS), seal colony soil (SCS) and emperor penguin colony soil (EPS) were collected. In laboratory, we investigated the effects of FTCs and water addition on potential N2O and CH4 production and respiration rates in the soils. The CH4 fluxes from OAS and SCS were much less than that from EPS. Meanwhile, the N2O fluxes from OAS and EPS were much less than that from SCS. The N2O production rates from all soils were extremely low during freezing, but rapidly increased following thawing. In all cases, FTC also induced considerably enhanced soil respiration, indicating that soil respiration response was sensitive to the FTCs. The highest cumulative rates of CH4, N2O and CO2 were 59.5 mg CH4-C∙kg-1 in EPS, 6268.8 µg N2O-N∙kg-1 in SCS and 3522.1 mg CO2-C∙kg-1 in OAS. Soil water addition had no significant effects on CH4 production and respiration rates, but it could reduce N2O production in OAS and EPS, and it stimulated N2O production in SCS. Overall, CH4 and N2O production rates showed a trade-off relationship during the three FTCs. Our results indicated that FTCs greatly stimulated soil N2O and CO2 production, and water increase has an important effect on soil N2O production in coastal Antarctic tundra.
  • LIU Hongwei, YU Ben, SHI Jianbo, ZHANG Qinghua, JIANG Guibin
    Advances in Polar Science. 2017, 28(1): 75-80. https://doi.org/10.13679/j.advps.2017.1.00075
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    Mercury (Hg) stable isotope analysis can provide new insight for understanding the biogeochemistry and sources of Hg in the polar regions. To completely extract the low contents of Hg in polar samples and to avoid isotopic fractionation during the sample preparation stage, an effective and reliable pretreatment method is needed. In this work, two different pretreatment methods were compared for measuring Hg stable isotopes in Antarctic moss samples. One method was acid digestion (HNO3:H2O2=5:3, v/v) and the second was a combustion-trapping treatment with a trapping solution (HNO3:HCl=2:1, v/v). There were no significant differences in the analytical results obtained with the two methods. The overall mean values and uncertainties of total Hg (THg) and the isotopic compositions of Hg in the referenced materials were all in good agreement with the certified and reported values, indicating that both methods were accurate and applicable. Acid digestion is highly efficient, while the combustion-trapping method can be used to treat samples with low Hg content. The proposed methods were successfully used to determine the Hg isotopic compositions in moss samples collected from the Antarctic.