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30 September 2018, Volume 30 Issue 3 Previous Issue    Next Issue

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Progress in Chinese research on marine atmospheric chemistry over the Southern Ocean Chen Liqi, Wang Jianjun, Zhan Liyang, Qidi, Zhang Miming, Gao Zhongyong, Zhao Shuhui, Yan Jinpei, Zhang Yuanhui, Lin Qi, Xu Suqing, Li Wei, Jiao Liping, Sun Heng, Zhang Jiexia, Lin Hongmei, et al 2018, 30 (3):  221-234.  DOI: 10.13679/j.jdyj.20180009 Abstract ( 836 )   PDF (425KB) ( 1018 )   Marine atmospheric chemistry is a frontier interdiscipline which combines marine chemistry and atmospheric chemistry. Chinese researches in marine atmospheric chemistry over the Southern Ocean has been advancing as a result of Chinese National Antarctic Research Expedition (CHINARE) since the early 1980s. Over more than 30 years, with the experience accumulation and data integration of Antarctic scientific investigation, the researches on the key processes of marine atmospheric chemistry over the Southern Ocean, namely the atmospheric-marine biogeochemical cycle of carbon, nitrogen, sulfur, phosphorus and iron, have made great progress. The research on the sea-air circulation of carbon and nitrogen and the sea-air particle exchange of sulfur, which is closely related to climate change, has led to new knowledge and achieved results. Chinese researches in marine atmospheric chemistry over the Southern Ocean focused on atmospheric aerosol chemical species characteristics and sources to explore key processes of atmospheric-marine geochemistry and estimate the sea-air exchange fluxes of sulfur, phosphorus and nitrogen. With the implementation of the project Antarctic Response and Feedback Role in Global Change, we improved our understanding of the global change sensitive elements such as carbon, nitrogen, sulfur and iron in the Southern Ocean and their effects on environment and climate. A deeper understanding has also been developed in the spatial distribution of carbon sinks in the sea ice zone of the Southern Ocean, and the sea-air exchange processes of DMS, MSA, N2O, Fe, as well as their impacts on the ecological environment. At the same time, important advances have been made in the research of technologies for underway observation of chemical species. Related Articles | Metrics

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Recent results obtained from dayside optical auroral observations at Yellow River Station Han Desheng, Hu Zejun, Chen Xiangcai, Liu Jianjun, Hu Hongqiao, Yang Huigen 2018, 30 (3):  235-250.  DOI: 10.13679/j.jdyj.20180020 Abstract ( 819 )   PDF (17167KB) ( 490 )   Recent results based on optical auroral observations at Yellow River Station are reviewed. A systematic study of dayside diffuse aurora has important implications for many topics, such as generation and distribution of cold plasmas in the dayside outer magnetosphere, and penetration of magnetosheath particles into the magnetosphere. We report a new auroral form, the “throat aurora”, and confirm it corresponds to localized magnetopause indentation using coordinated satellite and ground observations. The occurrence rate of throat aurora can be high, and the special scale of magnetopause indentation associated with it as large as 2–3 RE. We suggest that throat auroras are likely caused by a magnetosheath high-speed jet impacting on the magnetopause, and that they should be associated with magnetopause reconnection. We confirm that a special diffuse aurora can be generated from magnetosheath particle penetration into the magnetosphere associated with generation of throat aurora. We propose that transient structures locally generated in the magnetosheath (but not originating from solar wind) frequently cause indentations in the subsolar magnetopause, trigger reconnection, result in series of responses in geospace, and accordingly play an important role in solar wind-magnetosphere coupling. Related Articles | Metrics

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The progress of ecosystem and environment studies near Chinese Arctic Yellow River Station He Jianfeng, Li Chengsen, Yao Yifeng, Peng Fang, Wang Nengfei, Jin Haiyan, Zhang Fang, Ma Yuxin, Zhang Qinhua, Na Guangshui, Sun Liguang, Yuan Linxi, Jia Nan 2018, 30 (3):  251-267.  DOI: 10.13679/j.jdyj.20160048 Abstract ( 906 )   PDF (17377KB) ( 500 )   The Chinese Yellow River Station in Ny-Ålesund, Arctic Svalbard, is an ideal area for monitoring and studying the response of ecosystems to global change. Since its foundation in 2004, Chinese scientists have established a marine transect in Kongsfjorden and 11 terrestrial vegetation quadrats for monitoring, and projects on pollution and bird population evolution. Key research findings include: (1) species replacement is obvious in areas of glacial retreat, with mosses like Warnstorfia exannulata well reflecting variations in air temperature at the same period; (2) Bacterial strains have been isolated and 3 new genus and 21 new species have been discovered; (3) Kongsfjorden nanoplankton diversity is high, and during summer limited by surface-water nitrogen levels; (4) microalgae is highly adapted to temperature, and, by self-regulation, capable of adapting to environmental change; (5) tundra plants accumulate heavy metals, with atmospheric transmission the main pathway for persistent organic pollutant (POPs) population; and (6) since arriving in Ny-Ålesund 9 400 years ago, bird abundance has fluctuated with the maximum arriving 7 650 year ago. In the coming decades, the monitoring of marine transect and vegetaion quadrats should continue in order to know the trandency of population variations; meanwhile, combine the monitoring of atmosphere, glacier, plants and marine, carry out the study on atmosphere-ice-land-marine interation and form unique research feature. Related Articles | Metrics

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Geological surveys in East Antarctica by Chinese expeditions over the last 20 years: progress and#br# prospects Liu Xiaochun, Zhao Yue 2018, 30 (3):  268-286.  DOI: 10.13679/j.jdyj.20170047 Abstract ( 827 )   PDF (7348KB) ( 505 )   Fourteen geological surveys in East Antarctica from 1998 to 2017 were organized by the Chinese National Antarctic Research Expedition. The semicircular survey region has a radius of about 400 km from the Chinese Zhongshan Station in the Larsemann Hills. Main bedrock exposures in this area include the Grove Mountains, eastern Amery Ice Shelf-southwestern Prydz Bay, northern Prince Charles Mountains, Mount Brown, Rauer Group, and Vestfold Hills. Based on large- and medium-scale geological mapping and comprehensive multidisciplinary studies, the following has been achieved. (1) The Grove Subglacial Highlands has proven to be metamorphic terrain that experienced only a single Pan-African (~570–500 Ma) tectonometamorphic cycle. High-pressure mafic and pelitic granulites have been discovered from glacial moraines, and the Pan-African orogenic process has been accurately depicted. New data suggest that the Prydz Belt is a collisional zone, supporting a tectonic model that the Gondwana supercontinent was assembled from several continental blocks during Pan-African times. (2) A long-lived Mesoproterozoic continental arc exceeding >2 000 km occurs between the Indian and East Antarctic cratons. Arc magmatism lasted from ~1 500 Ma to ~ 1 000 Ma. It is proposed that the tectonic evolution of the Rayner orogen may involve an arc-continent collision followed by continent-continent collision during the Grenvillian (~1 000– 900 Ma) time. (3) Early kyanite relics have been identified from ultrahigh-temperature metapelites in the Rauer Group, and a precise clockwise P-T path of the ultrahigh-temperature metamorphism has been deduced. (4) Grenvillian (~960–940 Ma) heterogeneous granulitization with P-T conditions of 820–870?C and 0.84–0.97 GPa has been recognized in mafic dyke swarms from the southwestern Vestfold Block, suggesting that this block may have involved the Rayner orogeny during collision between the Indian and East Antarctic cratons. (5) U-Pb zircon ages of ~3.5–3.3 Ga have been obtained from weakly metamorphosed glacial boulders and loose sands from moraines around the southeastern margin of Vestfold Hills, on which basis it has been inferred that a possible Paleoarchean continental block exists beneath the ice sheet to the southeast of Vestfold Hills. It is suggested that future geological field investigations in the Indian Ocean sector of Antarctica should extend to the southern Prince Charles Mountains, the Napier Complex, and the Denman Glacier. Research should focus on the response of the Antarctic continent to the assembly and breakup of supercontinents in the geological history of the Earth. It can be carried out in the following aspects: (1) recognition of the Archean continental nuclei and their global correlations, (2) record of the Grenvillian orogeny and assembly of the Rodinia supercontinent, (3) record of the Pan-African orogeny and assembly of the Gondwana Supercontinent, and (4) breakup and dispersion of the supercontinent during the Phanerozoic. Such research will advance China’s research on Antarctic geology to ap-propriate international standards. Related Articles | Metrics

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A review of ice shelf-ocean interaction in Antarctica Shi Jiuxin 2018, 30 (3):  287-302.  DOI: 10.13679/j.jdyj.20180046 Abstract ( 940 )   PDF (7235KB) ( 775 )   Recent advances in the research of ice shelf–ocean interactions in Antarctica are reviewed in this paper. Basal melt rate of ice shelves exceeds calving flux, making bottom melt the dominant cause of mass loss in Antarctic ice sheets. Cavities under ice shelves can be classified into cold cavities—basal melt is driven by dense shelf water—and warm cavities—basal melt is driven by modified Circumpolar Deep Water. The giant Filchner–Ronne and Ross Ice Shelves in the Weddell and Ross Seas cover two-thirds of the total ice shelf area in Antarctica but mass loss from their cold cavities accounts for only 15% of the net melting of all ice shelves combined. Half of the net melting comes from several small, warm-cavity ice shelves in the Amundsen and Bellingshausen Seas in the Southeast Pacific sector, which cover 8% of the total ice shelf area. Modified Circumpolar Deep Water has been found to cause melting in the cold cavities under the Totten and Amery Ice Shelves in East Antarctica. Ice shelves cool and freshen seawater in their cavities. Ice shelf water from cavities is at a very low temperature and will modify shelf waters and even contribute to the formation of Antarctic Bottom Water. The recently observed freshening of Antarctic Bottom Water in the Pacific and Indian sectors might be attributed to the enhanced basal melting of upstream ice shelves. Related Articles | Metrics

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Bacterial catabolism of Dimethylsulfoniopropionate (DMSP) in polar marine areas Zeng Yinxin 2018, 30 (3):  303-313.  DOI: 10.13679/j.jdyj.20170037 Abstract ( 717 )   PDF (1146KB) ( 1205 )   Dimethylsulfoniopropionate (DMSP) is one of the most abundant organosulfur compounds on Earth, and a key nutrient for marine microorganisms. The main producers of DMSP are phytoplankton. DMSP is also the major precursor for gaseous dimethyl sulfide (DMS), which is important in global sulfur cycling and potentially affects weather and climate. Bacteria play an important role in the processes of DMSP degradation and DMS production. The pathways of DMSP synthesis and metabolism and the ecological impacts of DMSP have been studied for nearly 70 years. However, most of those studies have been performed at low- and mid-latitudes, and few experiments have been conducted in cold waters at high latitudes. In this review, I briefly introduce DMSP synthesis and catabolism, and then summarize recent advances in research on genes involved in DMSP degradation and the organisms that harbor those genes in polar marine areas. Studies on the bacterial metabolism of DMSP/DMS in polar marine areas will greatly improve our understanding of the role of microorganisms in the polar marine ecosystem, and the responses and feedback of marine microbial communities in the polar region to global climate change. Related Articles | Metrics

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Collection, research and prospects of micrometeorites from polar regions Xia Zhipeng, Miao Bingkui, Zhang Chuantong, Huang Lilin 2018, 30 (3):  314-328.  DOI: 10.13679/j.jdyj.20180014 Abstract ( 699 )   PDF (435KB) ( 672 )   The study of micrometeorites provides valuable insights into extraterrestrial environments and the evolution of the solar system. Since the 1940s, micrometeorite collection has been the focus of international research, with many scientific achievements made based on collections from polar regions. Although micrometeorite research in China occurred mainly between the 1980s and 1990s, it has more recently stagnated. This article summarizes discoveries regarding micrometeorites from polar regions, and proposes prospects and plans for future study. Related Articles | Metrics

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Arctic sea ice thickness retrieval based on SAR image texture feature Yu Miao, Lu Peng, Li Zhijun, Shi Lijian 2018, 30 (3):  329-337.  DOI: 10.13679/j.jdyj.20170035 Abstract ( 790 )   PDF (1188KB) ( 865 )   Utilize 7 Arctic SAR images and level ice thickness from 6th Arctic Survey，calculate texture feature through gray level co-occurrence matrix(GLCM)，confirm suitable GLCM parameters for thickness retrieval，analyze the relationship between sea-ice thickness and texture feature，validate the possibility of sea-ice thickness retrieval from texture feature. Then confirm fitting equation depending on the most suitable texture feature. When validated，the sea-ice thickness retrieval from the empirical equation agrees well with the in-situ data，the average relative error is 13.7%. This value is smaller compared with the commonly used method that only depend on backscattering coefficient，confirm the role of texture feature in sea-ice thickness retrieval. Related Articles | Metrics

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Construction of the suitability evaluation index for establishing Antarctic marine protected areas Pang Xiaoping, Ji Qing, Li Qinyu, Li Bingjie 2018, 30 (3):  338-348.  DOI: 10.13679/j.jdyj.20170031 Abstract ( 684 )   PDF (5569KB) ( 823 )   The Southern Ocean and Antarctic continent have scientific, economic and strategic significance because of their unique geographic location, extreme climate and abundant resources. Many countries have national interests in the region and are actively involved in the establishment of marine protected areas (MPAs) around Antarctica. Although China continues to pay attention to the Antarctic MPA, there are few relevant reports on MPAs, and suitability evaluation indices from model studies on the establishment of an Antarctic MPA are almost blank. Under these circumstances, this study attempted to construct a multilevel evaluation index system to help establish Antarctic MPAs, through analyzing existing proposals for an Antarctic MPA. Using Chinese Antarctic scientific investigation data, we also evaluate the suitability of establishing an MPA in the Prydz Bay. The aim of this study is to develop a reference index for the establishment and relevant researches of MPAs in the Antarctic region. Related Articles | Metrics