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Freeze-thaw processes of active-layer soils in the Nanweng'he River National Natural Reserve in the Da Xing'anling Mountains, northern Northeast China
Received:June 13, 2017  Revised:December 08, 2017  Click here to download the full text
Citation of this paper:RuiXia He,HuiJun Jin,XiaoLi Chang,YongPing Wang,LiZhong Wang,2018.Freeze-thaw processes of active-layer soils in the Nanweng'he River National Natural Reserve in the Da Xing'anling Mountains, northern Northeast China.Sciences in Cold and Arid Regions,10(2):104~113.
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Author NameAffiliationE-mail
RuiXia He State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China  
HuiJun Jin State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China;School of Civil Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150090, China hjjin@lzb.ac.cn 
XiaoLi Chang State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China;Hunan University of Science and Technology, Xiangtan, Hunan 411201, China  
YongPing Wang State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China;School of Civil Engineering, North University of Nationalities, Yinchuan, Ningxia 750030, China  
LiZhong Wang Nenjiangyuan Forest Ecosystem Research Station, Institute of Agriculture and Forestry, Da Xing'anling Forestry Group, Jiagedaqi, Heilongjiang 165000, China  
基金项目:This study was supported by the National Natural Science Foundation of China (Grant No. 41401081) and the State Key Laboratory of Frozen Soils Engineering (Grant Nos. SKLFSE-ZT-41, SKLFSE-ZT-20 and SKLFSE-ZT-12).
 
Abstract:The active-layer soils overlying the permafrost are the most thermodynamically active zone of rock or soil and play important roles in the earth-atmosphere energy system. The processes of thawing and freezing and their associated complex hydrothermal coupling can significantly affect variation in mean annual temperatures and the formation of ground ice in permafrost regions. Using soil-temperature and -moisture data obtained from the active layer between September 2011 and October 2014 in the permafrost region of the Nanweng'he River in the Da Xing'anling Mountains, the freeze-thaw characteristics of the permafrost were studied. Based on analysis of ground-temperature variation and hydrothermal transport characteristics, the thawing and freezing processes of the active layer were divided into three stages: (1) autumn-winter freezing, (2) winter freeze-up, and (3) spring-summer thawing. Variations in the soil temperature and moisture were analyzed during each stage of the freeze-thaw process, and the effects of the soil moisture and ground vegetation on the freeze-thaw are discussed in this paper. The study's results show that thawing in the active layer was unidirectional, while the ground freezing was bidirectional (upward from the bottom of the active layer and downward from the ground surface). During the annual freeze-thaw cycle, the migration of soil moisture had different characteristics at different stages. In general, during a freezing-thawing cycle, the soil-water molecules migrate downward, i.e., soil moisture transports from the entire active layer to the upper limit of the permafrost. In the meantime, freeze-thaw in the active layer can be significantly affected by the soil-moisture content and vegetation.
keywords:Nanweng'he River National Natural Reserve|active layer|freeze-thawing processes|moisture content|vegetation|effect
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