The Relation between Soil Moisture Phase Transitions and Soil Pore Structure under Freeze-Thaw Cycling

文献类型： 外文期刊

第一作者： Li, Qinglin

作者： Li, Qinglin;Qian, Yongqi;Peng, Xinhua;Wang, Yuekai;Peng, Xinhua

作者机构：

关键词： black soil (Mollisols); pore structure; soil moisture phase transitions (SMPT); thermal pulse time-domain reflection technology (T-TDR); X-ray computed tomography (X-CT)

期刊名称：AGRONOMY-BASEL （ 影响因子：3.4； 五年影响因子：3.8 ）

ISSN：

年卷期： 2024 年 14 卷 8 期

页码：

收录情况： SCI

摘要： The process of soil moisture phase transitions (SMPT) under freeze-thaw cycling is considered a key factor driving changes in soil pore structure. However, there is still no consensus on which indicators related to SMPT affect the soil pore structure. The objectives of this study were to compare SMPT and soil pore characteristics under freeze-thaw cycling, and to analyze the inherent relationship between them as affected by different bulk densities. Hence, we employed thermal pulse time-domain reflection technology (T-TDR) and X-ray CT scanning technology (X-CT) to quantitatively study the process of SMPT and pore characteristics of soil core samples (60 mm diameter, 100 mm height) repacked with three different bulk density levels: 1.10 gcm(-3) (NC), 1.30 gcm(-3) (LC) and their combination (1.10 gcm(-3) for upper half, 1.30 gcm(-3) for lower half, SC) under freeze-thaw cycling. Our results showed that compared with NC, the porosity of LC's 0-5 cm soil column decreased by 0.070 cm(3)cm(-3), the imaged porosity (phi(>60 mu m)) decreased by 0.034 cm(3)cm(-3), and the maximum soil ice content (MIC) decreased by 0.030 cm(3)cm(-3). The pores within the range of 200-300 mm (phi 2) and 300-400 mm (phi 3) contribute the most significantly to phi(>60 mu m) (50-60%). Soil initial moisture content (IMC) and MIC explained 50.1% of the change in phi 2, and the bulk density explained 49.3% of the change in phi 3. During the melting process, higher moisture content promotes the thaw collapse of soil particles, resulting in a decrease in phi(>60 mu m). The mean pore radius of the limiting layer (MRLL) and the hydraulic radius (HR) show that changes in bulk density from 1.10 gcm(-3) to 1.30 gcm(-3) do not have significant differences. Our results show the relationship between SMPT and pore structure change during freeze-thaw cycles as affected by initial soil bulk density and moisture condition.

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