Chinese Journal of Nature

Evolutions, functions and conservations of mountains-rivers-forests-croplands-lakesgrasslands-deserts system

SHI Yue, ZHAO Xia, ZHU Jiangling, FANG Jingyun

2022, 44(1): 1-18. doi:10.3969/j.issn.0253-9608.2022.01.001

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Mountains-rivers-forests-croplands-lakes-grasslands-deserts system is a brief summary and easy-to-understanding description of China’s diversified ecosystems. Despite the significant differences in the appearance and structures, mountains, rivers, forests, croplands, lakes, grasslands, and deserts together constitute a “community of life” through complex interconnections and interactions, providing material foundations and necessary conditions for the development of human society. At present, the integrated management, protection and restoration of the system have been an important starting point to promote the construction of ecological civilization in China. We summarize the background information on each component of the system, and briefly describe their formations and main functions. Meanwhile, we discuss how to conduct the governance, conservation and utilization of the system in the context of ecological civilization construction, review several cases which showed negative impacts on the environments, and briefly elaborate the measurements for ecological civilization construction from the perspective of ecology.

Measurements of the solar magnetic fields

LI Wenxian, TIAN Hui

2022, 44(1): 19-30. doi:10.3969/j.issn.0253-9608.2022.01.002

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The discovery of magnetic field in sunspots in 1908 brought solar physics from phenomenological observations to studies on the basis of physics. The solar magnetic field couples the solar interior with the visible surface of the Sun and with its entire atmosphere. Evolution of the solar magnetic field drives various types of activity in the solar atmosphere. The accurate measurement of solar magnetic fields is critical to our understanding of most unsolved problems in solar physics. In this article, we give an overview of the solar magnetic field measurements, including Hale’s discovery, history of solar magnetic field observations, and various methods for magnetic field measurements. The challenges and prospects for future research are also discussed.

Evolution of the South China Sea

SUN Zhen

2022, 44(1): 31-38. doi:10.3969/j.issn.0253-9608.2022.01.003

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South China Sea is the largest marginal sea of the eastern Asia. It has developed complex structures and rich hydrocarbon potential. For a long time, scientists are arguing about how South China Sea evolved into its present situation, as well as the deep driving mechanism and controlling factors. In order to resolve the above-mentioned questions, large amounts of geophysical investigations and 3 turns with 5 International Ocean Discovery Program (IODP) expeditions were carried out in South China Sea, which in turn led to significant progress. This paper summarized the dynamic attribute and the evolution history of the South China Sea based on the past decades of research progress. Three existing scientific questions were raised the following summary, including the mechanism of margin transition from active to passive, the breaking up pattern of the South China Sea continental margin and the dynamics of extraordinary large amount of magmatism during the South China Sea evolution. Hopefully these questions can be resolved through more cutting-edge investigation and IODP drilling expeditions, serving for the natural resources exploration and submarine hazards monitoring.

Arctic sea ice decline and its driving mechanisms

LIU Zhongfang

2022, 44(1): 39-46. doi:10.3969/j.issn.0253-9608.2022.01.004

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Polar sea ice plays an important role in global climate change. The Arctic is experiencing dramatic decline in sea ice coverage under global warming with a rate that is unprecedented over the past millennium. It is predicted that the Arctic Ocean will become ice-free during summertime in the middle of this century or even earlier. Arctic sea ice loss not only directly alters local environment and ecosystem, but also affects mid-latitude or even global weather and climate through large-scale oceanic and atmospheric circulation patterns. In this paper, we briefly review the characteristics of Arctic sea ice retreat and the associated physical mechanisms, and envisage prospect in the future work on mechanisms for Arctic sea ice retreat.

Isochron dating of metamorphic rocks

LI Xiaomeng, CHENG Hao

2022, 44(1): 47-56. doi:10.3969/j.issn.0253-9608.2022.01.005

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The nature of the glassy state is always one of the most exciting and fundamental issues in condensed matter physics and materials science. Metallic glasses provide ideal models for investigating amorphous physics due to the simple metal bonding and close-packed structure. Studies have found various orders in metallic glasses, among which medium-range order structures play an increasingly critical role in the phase transformation and deformation of amorphous alloys. However, the existing theories or experimental results are challenging to determine whether there is a structural connection between the amorphous state and its corresponding crystalline state in the medium range or more extensive length scale range. Moreover, the existing characterization methods are difficult to accurately analyze its short-range to medium-range order structure, further compounding its issue. Most recently, a unique metastable cubic phase has been found as an essential intermediate state during the heating process before crystallization in a classic bulk metallic glass Pd-Ni-P, and a hidden chiral medium-range structure bridging the amorphous state, and the crystalline state was captured and deciphered from the metastable cube phase. The medium-range structure is named the sixmembered tricapped trigonal prism (6M-TTP) cluster. This structure’s short-range clusters are organized as a peculiar chiral structure to form a medium-range building block with about 12.5 Å. The 6M-TTP clusters tend to randomly pack to be long-range disordered structures in the as-cast state and later transform to be an ordered cubic metastable phase at a certain temperature. In order to reveal the nature of the amorphous structure, a new structural model is provided, and a new explanation is proposed for the precipitation kinetics of metastable mesophase in metallic glasses. These findings will help clarify the structural arrangement of metallic glasses in the medium-range and even more extensive length scales. Our findings would shed light on capture and decipher more building blocks of medium-range ordering in amorphous alloys and would help solve the long-standing issue of amorphous structures.

Birth of the first world ocean floor map

ZHANG Hanke, YAN Bing

2022, 44(1): 72-78. doi:10.3969/j.issn.0253-9608.2022.01.007

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In 1977, American scientists Marie Tharp and Bruce Heezen published the world’s first ocean floor map, in which various characteristics of the ocean floor were displayed completely and intuitively in front of the world for the first time. The map caused a great sensation at that time. Even now, it still has an unshakable status in the field of geosciences. Behind this map was the systematic and hard work by the two scientists on the world ocean floor for more than 20 years. This paper reviews the process, technology and methods of the research, and reveals the significance of their research.

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