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The dynamics of pore space structure in different filled soil constructions during water infiltration and wetting–drying processes is studied. Model laboratory experiments in columns physically simulate water infiltration after penetration at a rate of 600 mm with free outflow from the lower end of the column followed by multiple drying of soil constructions composed by alternating layers of sand, peat, and A and В horizons of soddy-podzolic soil. In two- and three-dimensional tomographic images, changes in the pore space and the interpenetration of solid phase at the boundaries between individual horizons of soil constructions are analyzed. 相似文献
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E. B. Skvortsova E. V. Shein K. N. Abrosimov K. A. Romanenko A. V. Yudina V. V. Klyueva D. D. Khaidapova V. V. Rogov 《Eurasian Soil Science》2018,51(2):190-198
With the help of computed X-ray microtomography with a resolution of 2.75 μm, changes in the microstructure and pore space of aggregates of 3 mm in diameter from the virgin soddy-podzolic soil (Glossic Retisol (Loamic)) in the air-dry, capillary-moistened, and frozen states after five freeze–thaw cycles were studied in a laboratory experiment. The freezing of the samples was performed at their capillary moistening. It was shown that capillary moistening of initially air-dry samples from the humus (AY), eluvial (EL), and illuvial (BT1) horizons at room temperature resulted in the development of the platy, fine vesicular, and angular blocky microstructure, respectively. The total volume of tomographically visible pores >10 μm increased by 1.3, 2.2, and 3.4 times, respectively. After freeze–thaw cycles, frozen aggregates partly preserved the structural arrangement formed during the capillary moistening. At the same time, in the frozen aggregate from the AY horizon, the total tomographic porosity decreased to the initial level of the air-dry soil. In the frozen aggregate from the EL horizon, large vesicular pores were formed, owing to which the total pore volume retained its increased values. The resistance of aggregate shape to the action of freeze–thaw cycles differed. The aggregate from the EL horizon completely lost its original configuration by the end of the experiment. The aggregate from the AY horizon displayed definite features of sagging after five freeze–thaw cycles, whereas the aggregate from the BT1 horizon preserved its original configuration. 相似文献
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E. V. Shein E. B. Skvortsova A. V. Dembovetskii K. N. Abrosimov L. I. Il’in N. A. Shnyrev 《Eurasian Soil Science》2016,49(3):315-325
Pore-size distribution in a soddy-podzolic silt loamy soil developing from mantle loesslike loam (Eutric Albic Retisol (Loamic, Cutanic)) was calculated from the water retention curve according to Jurin’s equation and directly determined in microtomographic experiments. Rounded macropores with the diameter of their sections from 75 to 1000 μm predominate in horizontal sections if the studied soil samples. A larger part of the soil pores (>30–35%) belongs to micro- and nanopores, and they cannot be quantitatively determined by the tomographic method, because their sizes are smaller than the detection limit of the applied X-ray microtomography (8.75 μm per pixel). This leads to a significantly larger pore volume determined from the water retention curve in comparison with the “tomographic” pore volume. A comparative analysis of pore-size distribution curves obtained by these methods shows that the major regularities of the pore-size distribution in the range from 30 to 5000 μm are similar in both cases. Fine macropores and, partly, mesopores predominate. Common characteristics of the pore-size distribution curves obtained by these methods, including the coincidence of the peaks, attest to the validity of classical approaches, according to which the hydrology of soil pore space can be perceived as a physical model of cylindrical capillaries of different sizes with capillary-sorbed water. 相似文献
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D. D. Khaidapova V. V. Klyueva E. B. Skvortsova K. N. Abrosimov 《Eurasian Soil Science》2018,51(10):1191-1199
Coupled studies of pore space and rheological behavior of undisturbed samples from soddypodzolic soils (Albic Glossic Retisols (Loamic, Aric, Cutanic)) of Moscow oblast under forest and under cropland and from typical chernozems (Haplic Chernozems (Loamic, Aric, Pachic)) of Kursk oblast under oak forest, shelterbelt, and cropland were conducted. Soil pore space was investigated using a Bruker SkyScan 1172 G (Belgium) microtomograph, and 3D models of pore space were constructed. The total pore space (in percent of the volume of analyzed samples) and the volumes of open and closed pores were determined from these models. The nondestructive tomographic method made it possible to analyze the rheological properties of soils for the same samples using the amplitude sweep method on an MCR-302 (Anton Paar, Austria) rheometer. The following parameters of the rheological behavior were determined: storage modulus in the range of linear viscoelastic behavior, the range of linear viscoelastic behavior, and the range of plastic behavior. A joint analysis of the rheological properties and morphometric characteristics of the undisturbed samples of soddy-podzolic soils and chernozems demonstrated the dependence of the rheological behavior of these soils on their physicochemical properties and pore space structure reflecting the differences in the genesis and physical and chemical properties of soil horizons. The correlation analysis attested to direct (positive) relationships between the values of the total and open tomographic porosities, the range of linear viscoelastic behavior, and the deformation upon the destruction of soil structure. Negative relationships were found between the values of open and total porosity and the structural strength of the soil monoliths. A hypothesis about an increase in the range of plastic behavior of soils and a decrease in the strength of soil structure with an increase in porosity was suggested. 相似文献
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Skvortsova E. B. Shein E. V. Romanenko K. A. Abrosimov K. N. 《Eurasian Soil Science》2020,53(7):913-921
Eurasian Soil Science - In this article, we discuss the contribution of capillary wetting and multiple freezing and thawing to the formation and evolution of vesicular micro– and mesoporosity... 相似文献
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Kalnin T. G. Ivonin D. A. Abrosimov K. N. Grachev E. A. Sorokina N. V. 《Eurasian Soil Science》2021,54(9):1400-1409
Eurasian Soil Science - The technique of numerical analysis of three-dimensional tomographic images of the pore space of soil objects has been used in this paper. It applies methods of integral... 相似文献
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Abrosimov K. N. Gerke K. M. Fomin D. S. Romanenko K. A. Korost D. V. 《Eurasian Soil Science》2021,54(9):1385-1399
Eurasian Soil Science - The article provides an overview of the use of computed tomography in the study of soils from the first works to the present time. The development of computed tomography in... 相似文献
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The composition and structure of aggregates from different agrogenic soils in the southern steppe zone of European Russia have been studied. It is shown that the multi-level study (from the macro- to microlevel) of these horizons makes it possible to identify soil compaction caused by different elementary soil processes: solonetz-forming, vertisol-forming, and mechanical (wheel) compaction in the rainfed and irrigated soils. The understanding of the genesis of the compaction of soil horizons (natural or anthropogenic) is important for the economic evaluation of soil degradation. It should enable us to make more exact predictions of the rates of degradation processes and undertake adequate mitigation measures. The combined tomographic and micromorphological studies of aggregates of 1–2 and 3–5 mm in diameter from compacted horizons of different soils have been performed for the first time. Additional diagnostic features of negative solonetz- forming processes (low open porosity of aggregates seen on tomograms and filling of a considerable part of the intraped pores with mobile substance) and the vertisol-forming processes (large amount of fine intraaggregate pores seen on tomograms and a virtual absence of humus–clay plasma in the intraped zone)—have been identified. It is shown that the combination of microtomographic and micromorphological methods is helpful for studying the pore space of compacted horizons in cultivated soils. 相似文献
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