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Experiments on the Resistance of a Large Transport Vessel Navigating in the arctic region in Pack Ice Conditions

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Journal of Marine Science and Application 2016年第3期15卷 269-274页

作者： Yan Huang Wei Li Yinghui Wang Baoshan Wu State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin University Tianjin 300072 China China Ship Scientific Research Center Wuxi 214082 China

In this study, we carried out model tests to investigate the ice failure process and the resistance experienced by a transport vessel navigating in the arctic region in pack ice conditions. We tested different navigation velocities, ice plate sizes, and ice concentrations. During the tests, we closely observed several phenomena, including the modes of interaction of the ice ship and the moving and failure modes of ice. We also measured the vessel resistances under different conditions. The test results indicate that the navigation velocity is a significant determinant of the moving and failure modes of ice. Moreover, vessel resistance is remarkably dependent on the ice concentration and navigation velocity. The variances of the mean and maximum resistance are also compared and discussed in detail.

关键词： model test arctic region pack ice condition ice concentration vessel resistance transport vessel

Summertime CO_2 fluxes from tundra of Ny-?lesund in the High arctic

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Advances in Polar Science 2017年第1期28卷 50-60页

作者： LI Fangfang ZHU Renbin BAO Tao WANG Qing XU Hua Anhui Province key Laboratory of Polar Environment and Global Change School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230036China State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008China

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-A.lesund 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 Qm 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.

关键词： CO2 fluxes net ecosystem exchange （NEE） ecosystem respiration （ER） gross photosynthesis arctic region

Advances in Chinese arctic and subarctic research in marine biology and ecology with emphasis on the Pacific arctic sector

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Advances in Polar Science 2017年第2期28卷 111-119页

作者： LI Hai LIN Longshan SONG Puqing LI Yuan ZHANG Ran LIN Heshan LIN Rongcheng HAO Qiang ZHANG Fang ZHANG Guangtao Third Institute of Oceanography State Oceanic Administration Second Institute of Oceanography State Oceanic Administration SOA Key Laboratory for Polar Science Polar Research Institute of China Institute of Oceanology Chinese Academy of Sciences

The arctic is one of the most sensitive regions that respond through feedback to global climate changes. Climatic, hydrological and ecological changes in the arctic are clear evidence of global warming. In 2012 and 2014, the 5th and 6th Chinese National arctic Research Expeditions undertook studies in the Bering Sea, the arctic Ocean （including the Chukchi Sea）, and the Norwegian Sea. These studies provided us with a better understanding of the marine biology and ecology in the arctic and subarctic regions, particularly in the Pacific arctic sector. Rapid changes observed in the arctic environment include the shrinking of cold-water masses in the Bering Sea in the summer, and elevated water temperatures promoting phytoplankton blooms, leading to an increase in phytoplankton transferred to higher trophic levels. As a result, the transfer efficiency of organic matter toward the bottom weakened, leading to a reduction in benthic biomass. This is consistent with expectations that the overall carbon and energy flux will ultimately switch from the dominant mode of sea ice-algae-benthos to one of phytoplankton-zooplankton. Influenced by Pacific water inflow, fluvial runoff and melting sea ice, the Chukchi Sea exhibited different responses to various environmental changes. Interactions between water masses led to other interannual ecological shifts. With the increase in sea ice melt and sunlight in the central region of the arctic Ocean, the relative abundance of heterotrophic bacteria is expected to increase, and play a vital role in the arctic microbial loop.

关键词： arctic region climate changes chlorophyll plankton benthos microbe food chain