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In this study, magnetic resonance imaging (MRI) was used to investigate the freezing and thawing ... more In this study, magnetic resonance imaging (MRI) was used to investigate the freezing and thawing process of a series of repacked samples of sand, soil, and sand-soil mixture. The samples were placed in a thermally insulated container inside a vertical bore MRI scanner and cooled by flowing cold gaseous nitrogen through a porous material at the top of the container. Temperatures were monitored in several points above the sample and at the sample surface, and a marker placed on the sample surface was used to measure sample deformation. A 4.7 T magnet was used for MRI and the Multiple-Slice Spin-Echo (MSME) and Zero Echo Time (ZTE) pulse sequences were employed to obtain the images. The contrast between the frozen and unfrozen water in the samples was given by the substantial difference in T1 and T2 relaxation times between the two states. The hydrogen in the frozen water does not produce any signal for both pulse sequences, thus all the signal represent the liquid/unfrozen water. The time-lapse three-dimensional (3D) imaging was performed during the entire course of the experiment with alternating use of the MSME and ZTE imaging techniques. Once the freezing front reached near the bottom of the sample, the thawing process was initiated by switching the inflow of cooling gas to the inflow of nitrogen at room temperature. The small changes in sand structure as a consequence of volumetric ice-water changes were studied using spatiotemporal analysis of the freezing front advancement and frozen water volume. The study detected interesting patterns of preferential thawing on the onset of thawing process in the case of sand. The MSME pulse sequence was successfully used to image the process in the sand, whereas the ZTE was capable of detecting water in the finer soil material. The data obtained in the study were used to develop two-phase ice-water simulation models to interpret the experimental results and better understand the freezing and thawing phenomena.
Freezing and thawing cycles in laboratory were studied. Freezing-thawing cycles were carried out ... more Freezing and thawing cycles in laboratory were studied. Freezing-thawing cycles were carried out in the laboratory on fully saturated packed sand sample (15 cm in diameter and 20 cm in height). Series of freezing-thawing cycles were conducted with newly designed experimental setup. The setup consisted of inner plastic tube covered on its sides and outer plastic tube. The column sample was placed into the precisely controlled freezer chamber. The top of the sample was covered by an aluminum lid. Initially the sample was equilibrated at +10 °C then the temperature inside the chamber was changed to -10 °C. The inner temperature of the sample was monitored in three depths by thin temperature sensors (109 SS, Campbell Scientific, USA) horizontally inserted into the sample. The experiment aims to provide information on freezing dynamics and thermo-mechanical changes during the freezing and thawing cycles. Horizontal gradient within freezing cycle was monitored. The data were compared with simulations obtained by a numerical model (Žák et al., 2013). The model is based on the heat balance within the sample assembly and a modified heat equation for the porous medium temperature allowing for the phase transition below the freezing point depression.
EGUGA, Apr 1, 2012
ABSTRACT Pore system of some soils may not become fully saturated during ponded infiltration due ... more ABSTRACT Pore system of some soils may not become fully saturated during ponded infiltration due to air entrapment. Varying entrapped air content then determines quasi-saturated water content of soil and can strongly affect soil quasi-saturated hydraulic conductivity. This study shows changes of quasi-saturated volumetric water content in time measured by time domain reflectometry (TDR) during the infiltration outflow experiment conducted on medium sized soil column in the laboratory. Experiments were conducted on a packed sample of fine quartz sand and on undisturbed soil. The undisturbed soil sample (internal diameter 189 mm and 250 mm height) of sandy loam soil was collected at the experimental site Uhlirska (Jizera Mountains, Czech Republic). Recurrent ponded infiltration experiment, conducted on each sample, consisted of three infiltration runs. The same level of ponding was maintained during each infiltration run at the top of the sample. Water drained freely through the perforated plate at the bottom of the sample. First infiltration run was done into naturally dry soil while subsequent runs were conducted into wet soil. The degassed water was used for the third infiltration run. The apparent dielectric constants were monitored at depths 75, 125 and 175 mm bellow the sample surface using the 7.5 cm long TDR probes connected to Campbell Scientific TDR100 reflectometer via multiplexor. Volumetric water contents in each depth were calculated from apparent dielectric constants using Topp's equation. Additionally, the pulse of potassium bromide was applied repeatedly during the quasi-steady state of each infiltration run, while the bromide breakthrough was monitored both in the effluent (by ion selective electrode) and in the sample by TDR (as changes of electric conductivity). Experimental results showed that in case of homogenously packed sand the quasi-steady state flow rates and water contents were nearly the same during all three infiltration runs. The undisturbed sandy loam sample exhibited drop of the flow rates between the first and second infiltration run and a gradual recovery of flow rates and water contents during the third run. This supports the assumption that air that was trapped in the flow pathways when water infiltrated in wet soil was dissolved in degassed water during the third run. The TDR probes show the dynamics of the quasi-saturated water content changes. This research has been supported by GACR 103/08/1552.
Vodni režim i vegetacni skladba revitalizovaných raselinisť v Jizerských horach je hydrologicky a... more Vodni režim i vegetacni skladba revitalizovaných raselinisť v Jizerských horach je hydrologicky a botanicky monitorovan. Pro korekci teto technicke změny, ke ktere dochazi na pozadi dlouhodobeho vývoje krajiny jsou stejným způsobem monitorovany i nedaleke přirozene technicky neovlivněne plochy.
Journal of Hydrology and Hydromechanics, Jul 22, 2017
Isothermal and non-isothermal infiltration experiments with tracer breakthrough were carried out ... more Isothermal and non-isothermal infiltration experiments with tracer breakthrough were carried out in the laboratory on one intact column (18.9 cm in diameter, 25 cm in height) of sandy loam soil. For the isothermal experiment, the temperature of the infiltrating water was 20°C to the initial temperature of the sample. For the two non-isothermal experiments water temperature was set at 8°C and 6°C, while the initial temperature of the sample was 22°C. The experiments were conducted under the same initial and boundary conditions. Pressure heads and temperatures were monitored in two depths (8.8 and 15.3 cm) inside the soil sample. Two additional temperature sensors monitored the entering and leaving temperatures of the water. Water drained freely through the perforated plate at the bottom of the sample by gravity and outflow was measured using a tipping bucket flowmeter. The permeability of the sample calculated for steady state stages of the experiment showed that the significant difference between water flow rates recorded during the two experiments could not only be justified by temperature induced changes of the water viscosity and density. The observed data points of the breakthrough curve were successfully fitted using the two-region physical non-equilibrium model. The results of the breakthrough curves showed similar asymmetric shapes under isothermal and non-isothermal conditions.
Soil & Tillage Research, Jul 1, 2020
In structured soils, water and reactive solutes can move preferentially through larger inter-aggr... more In structured soils, water and reactive solutes can move preferentially through larger inter-aggregate macropores (biopores and cracks) and smaller intra-aggregate pores. Especially clay-organic coating material is of major importance for the exchange of water and solutes between macro-and micropores and the soil matrix by affecting the reactive transport in a yet largely unknown way. The objective of this study was to compare the adsorption and desorption behaviour of clay-organic coatings from samples of till-(T-Bt) and loess-(L-Bt) derived Bt horizons of Haplic Luvisols with those of the soil matrix and a hillslope loam-derived Bsh (HL-Bsh) horizon of a forest Cambisol-Podzol (CM-PZ) without coatings. These coatings are characterized by q m-values of up to 1100 μmol cm −3 for clay contents of up to 330 g kg-1. The values are significantly higher than those of mixed samples without coatings (q m of 180 μmol cm −3 for clay content of 115 g kg-1). The results indicate two different adsorption mechanisms, i) sorption on siloxane surfaces of the alumosilicates (clay minerals) and ii) adsorption controlled by hydrophobic interaction with soil organic material which is possibly attached to clay-organic complexes. The great difference in sorption properties between coatings and matrix suggests that mean values obtained from analyzing mixed samples cannot be used to describe the retardation of dissolved reactive substances on the surfaces of biopores and larger cracks during preferential flow events.
Journal of Soils and Sediments, Sep 24, 2020
Soil & Tillage Research, Oct 1, 2020
In structured soils, clay-organic coatings are spatially distributed along macropore surfaces. In... more In structured soils, clay-organic coatings are spatially distributed along macropore surfaces. Information on thickness and volume of coating material is essential for macropore-matrix mass exchange of water and solutes. However, their determination is difficult and fraught with uncertainty due to irregular shapes of macropore surfaces. The objective of this study was to test the use of a three-dimensional (3D) confocal laser scanning microscope for gauging soil macropore coatings. For this test, coating material was manually separated from the surface of intact soil clods (5 cm edge length) sampled from Bt horizons (with illuvial clay) of till-derived and loess-derived Haplic Luvisols. The resulting coating thicknesses ranged between approx. 0.1 and 0.5 mm and volumes between 0.057 and 2.9 mm 3 with mean densities of 1.96 g cm −3 for loess-derived and 2.67 g cm −3 for till-derived coatings. The 3D laser microscopic method yielded data based on micro-topographic information. The key benefits of the 3D confocal laser scanning microscope are the information on the mm-scale spatial distribution of coating thickness and bulk density. These additional parameters of the clod surface or aggregate micro-topography can be useful for improved quantification of accessibility of sorption surfaces and for describing macropore-matrix mass transfer of reactive solutes.
EGUGA, Apr 1, 2017
Isothermal and non-isothermal infiltration experiments with tracer breakthrough were carried out ... more Isothermal and non-isothermal infiltration experiments with tracer breakthrough were carried out in the laboratory on one intact column (18.9 cm in diameter, 25 cm in height) of sandy loam soil. For the isothermal experiment, the temperature of the infiltrating water was 20°C to the initial temperature of the sample. For the two non-isothermal experiments water temperature was set at 8°C and 6°C, while the initial temperature of the sample was 22°C. The experiments were conducted under the same initial and boundary conditions. Pressure heads and temperatures were monitored in two depths (8.8 and 15.3 cm) inside the soil sample. Two additional temperature sensors monitored the entering and leaving temperatures of the water. Water drained freely through the perforated plate at the bottom of the sample by gravity and outflow was measured using a tipping bucket flowmeter. The permeability of the sample calculated for steady state stages of the experiment showed that the significant difference between water flow rates recorded during the two experiments could not only be justified by temperature induced changes of the water viscosity and density. The observed data points of the breakthrough curve were successfully fitted using the two-region physical non-equilibrium model. The results of the breakthrough curves showed similar asymmetric shapes under isothermal and non-isothermal conditions.
EGU General Assembly Conference Abstracts, May 1, 2014
Journal of Environmental Engineering, Apr 1, 2019
AbstractCryptosporidia are opportunistic pathogens, some of which infect humans when ingested in ... more AbstractCryptosporidia are opportunistic pathogens, some of which infect humans when ingested in water or food. Filtration through granular media is the primary mechanism to remove them from water....
Freezing and thawing cycles in laboratory were studied. Freezing-thawing cycles were carried out ... more Freezing and thawing cycles in laboratory were studied. Freezing-thawing cycles were carried out in the laboratory on fully saturated packed sand sample (15 cm in diameter and 20 cm in height). Series of freezing-thawing cycles were conducted with newly designed experimental setup. The setup consisted of inner plastic tube covered on its sides and outer plastic tube. The column sample was placed into the precisely controlled freezer chamber. The top of the sample was covered by an aluminum lid. Initially the sample was equilibrated at +10 °C then the temperature inside the chamber was changed to -10 °C. The inner temperature of the sample was monitored in three depths by thin temperature sensors (109 SS, Campbell Scientific, USA) horizontally inserted into the sample. The experiment aims to provide information on freezing dynamics and thermo-mechanical changes during the freezing and thawing cycles. Horizontal gradient within freezing cycle was monitored. The data were compared with...
In this study, magnetic resonance imaging (MRI) was used to investigate the freezing and thawing ... more In this study, magnetic resonance imaging (MRI) was used to investigate the freezing and thawing process of a series of repacked samples of sand, soil, and sand-soil mixture. The samples were placed in a thermally insulated container inside a vertical bore MRI scanner and cooled by flowing cold gaseous nitrogen through a porous material at the top of the container. Temperatures were monitored in several points above the sample and at the sample surface, and a marker placed on the sample surface was used to measure sample deformation. A 4.7 T magnet was used for MRI and the Multiple-Slice Spin-Echo (MSME) and Zero Echo Time (ZTE) pulse sequences were employed to obtain the images. The contrast between the frozen and unfrozen water in the samples was given by the substantial difference in T1 and T2 relaxation times between the two states. The hydrogen in the frozen water does not produce any signal for both pulse sequences, thus all the signal represent the liquid/unfrozen water. The ...
AGU Fall Meeting Abstracts, Dec 1, 2018
EGU General Assembly Conference Abstracts, Apr 1, 2019
In this study, magnetic resonance imaging (MRI) was used to investigate the freezing and thawing ... more In this study, magnetic resonance imaging (MRI) was used to investigate the freezing and thawing process of a series of repacked samples of sand, soil, and sand-soil mixture. The samples were placed in a thermally insulated container inside a vertical bore MRI scanner and cooled by flowing cold gaseous nitrogen through a porous material at the top of the container. Temperatures were monitored in several points above the sample and at the sample surface, and a marker placed on the sample surface was used to measure sample deformation. A 4.7 T magnet was used for MRI and the Multiple-Slice Spin-Echo (MSME) and Zero Echo Time (ZTE) pulse sequences were employed to obtain the images. The contrast between the frozen and unfrozen water in the samples was given by the substantial difference in T1 and T2 relaxation times between the two states. The hydrogen in the frozen water does not produce any signal for both pulse sequences, thus all the signal represent the liquid/unfrozen water. The time-lapse three-dimensional (3D) imaging was performed during the entire course of the experiment with alternating use of the MSME and ZTE imaging techniques. Once the freezing front reached near the bottom of the sample, the thawing process was initiated by switching the inflow of cooling gas to the inflow of nitrogen at room temperature. The small changes in sand structure as a consequence of volumetric ice-water changes were studied using spatiotemporal analysis of the freezing front advancement and frozen water volume. The study detected interesting patterns of preferential thawing on the onset of thawing process in the case of sand. The MSME pulse sequence was successfully used to image the process in the sand, whereas the ZTE was capable of detecting water in the finer soil material. The data obtained in the study were used to develop two-phase ice-water simulation models to interpret the experimental results and better understand the freezing and thawing phenomena.
Freezing and thawing cycles in laboratory were studied. Freezing-thawing cycles were carried out ... more Freezing and thawing cycles in laboratory were studied. Freezing-thawing cycles were carried out in the laboratory on fully saturated packed sand sample (15 cm in diameter and 20 cm in height). Series of freezing-thawing cycles were conducted with newly designed experimental setup. The setup consisted of inner plastic tube covered on its sides and outer plastic tube. The column sample was placed into the precisely controlled freezer chamber. The top of the sample was covered by an aluminum lid. Initially the sample was equilibrated at +10 °C then the temperature inside the chamber was changed to -10 °C. The inner temperature of the sample was monitored in three depths by thin temperature sensors (109 SS, Campbell Scientific, USA) horizontally inserted into the sample. The experiment aims to provide information on freezing dynamics and thermo-mechanical changes during the freezing and thawing cycles. Horizontal gradient within freezing cycle was monitored. The data were compared with simulations obtained by a numerical model (Žák et al., 2013). The model is based on the heat balance within the sample assembly and a modified heat equation for the porous medium temperature allowing for the phase transition below the freezing point depression.
EGUGA, Apr 1, 2012
ABSTRACT Pore system of some soils may not become fully saturated during ponded infiltration due ... more ABSTRACT Pore system of some soils may not become fully saturated during ponded infiltration due to air entrapment. Varying entrapped air content then determines quasi-saturated water content of soil and can strongly affect soil quasi-saturated hydraulic conductivity. This study shows changes of quasi-saturated volumetric water content in time measured by time domain reflectometry (TDR) during the infiltration outflow experiment conducted on medium sized soil column in the laboratory. Experiments were conducted on a packed sample of fine quartz sand and on undisturbed soil. The undisturbed soil sample (internal diameter 189 mm and 250 mm height) of sandy loam soil was collected at the experimental site Uhlirska (Jizera Mountains, Czech Republic). Recurrent ponded infiltration experiment, conducted on each sample, consisted of three infiltration runs. The same level of ponding was maintained during each infiltration run at the top of the sample. Water drained freely through the perforated plate at the bottom of the sample. First infiltration run was done into naturally dry soil while subsequent runs were conducted into wet soil. The degassed water was used for the third infiltration run. The apparent dielectric constants were monitored at depths 75, 125 and 175 mm bellow the sample surface using the 7.5 cm long TDR probes connected to Campbell Scientific TDR100 reflectometer via multiplexor. Volumetric water contents in each depth were calculated from apparent dielectric constants using Topp's equation. Additionally, the pulse of potassium bromide was applied repeatedly during the quasi-steady state of each infiltration run, while the bromide breakthrough was monitored both in the effluent (by ion selective electrode) and in the sample by TDR (as changes of electric conductivity). Experimental results showed that in case of homogenously packed sand the quasi-steady state flow rates and water contents were nearly the same during all three infiltration runs. The undisturbed sandy loam sample exhibited drop of the flow rates between the first and second infiltration run and a gradual recovery of flow rates and water contents during the third run. This supports the assumption that air that was trapped in the flow pathways when water infiltrated in wet soil was dissolved in degassed water during the third run. The TDR probes show the dynamics of the quasi-saturated water content changes. This research has been supported by GACR 103/08/1552.
Vodni režim i vegetacni skladba revitalizovaných raselinisť v Jizerských horach je hydrologicky a... more Vodni režim i vegetacni skladba revitalizovaných raselinisť v Jizerských horach je hydrologicky a botanicky monitorovan. Pro korekci teto technicke změny, ke ktere dochazi na pozadi dlouhodobeho vývoje krajiny jsou stejným způsobem monitorovany i nedaleke přirozene technicky neovlivněne plochy.
Journal of Hydrology and Hydromechanics, Jul 22, 2017
Isothermal and non-isothermal infiltration experiments with tracer breakthrough were carried out ... more Isothermal and non-isothermal infiltration experiments with tracer breakthrough were carried out in the laboratory on one intact column (18.9 cm in diameter, 25 cm in height) of sandy loam soil. For the isothermal experiment, the temperature of the infiltrating water was 20°C to the initial temperature of the sample. For the two non-isothermal experiments water temperature was set at 8°C and 6°C, while the initial temperature of the sample was 22°C. The experiments were conducted under the same initial and boundary conditions. Pressure heads and temperatures were monitored in two depths (8.8 and 15.3 cm) inside the soil sample. Two additional temperature sensors monitored the entering and leaving temperatures of the water. Water drained freely through the perforated plate at the bottom of the sample by gravity and outflow was measured using a tipping bucket flowmeter. The permeability of the sample calculated for steady state stages of the experiment showed that the significant difference between water flow rates recorded during the two experiments could not only be justified by temperature induced changes of the water viscosity and density. The observed data points of the breakthrough curve were successfully fitted using the two-region physical non-equilibrium model. The results of the breakthrough curves showed similar asymmetric shapes under isothermal and non-isothermal conditions.
Soil & Tillage Research, Jul 1, 2020
In structured soils, water and reactive solutes can move preferentially through larger inter-aggr... more In structured soils, water and reactive solutes can move preferentially through larger inter-aggregate macropores (biopores and cracks) and smaller intra-aggregate pores. Especially clay-organic coating material is of major importance for the exchange of water and solutes between macro-and micropores and the soil matrix by affecting the reactive transport in a yet largely unknown way. The objective of this study was to compare the adsorption and desorption behaviour of clay-organic coatings from samples of till-(T-Bt) and loess-(L-Bt) derived Bt horizons of Haplic Luvisols with those of the soil matrix and a hillslope loam-derived Bsh (HL-Bsh) horizon of a forest Cambisol-Podzol (CM-PZ) without coatings. These coatings are characterized by q m-values of up to 1100 μmol cm −3 for clay contents of up to 330 g kg-1. The values are significantly higher than those of mixed samples without coatings (q m of 180 μmol cm −3 for clay content of 115 g kg-1). The results indicate two different adsorption mechanisms, i) sorption on siloxane surfaces of the alumosilicates (clay minerals) and ii) adsorption controlled by hydrophobic interaction with soil organic material which is possibly attached to clay-organic complexes. The great difference in sorption properties between coatings and matrix suggests that mean values obtained from analyzing mixed samples cannot be used to describe the retardation of dissolved reactive substances on the surfaces of biopores and larger cracks during preferential flow events.
Journal of Soils and Sediments, Sep 24, 2020
Soil & Tillage Research, Oct 1, 2020
In structured soils, clay-organic coatings are spatially distributed along macropore surfaces. In... more In structured soils, clay-organic coatings are spatially distributed along macropore surfaces. Information on thickness and volume of coating material is essential for macropore-matrix mass exchange of water and solutes. However, their determination is difficult and fraught with uncertainty due to irregular shapes of macropore surfaces. The objective of this study was to test the use of a three-dimensional (3D) confocal laser scanning microscope for gauging soil macropore coatings. For this test, coating material was manually separated from the surface of intact soil clods (5 cm edge length) sampled from Bt horizons (with illuvial clay) of till-derived and loess-derived Haplic Luvisols. The resulting coating thicknesses ranged between approx. 0.1 and 0.5 mm and volumes between 0.057 and 2.9 mm 3 with mean densities of 1.96 g cm −3 for loess-derived and 2.67 g cm −3 for till-derived coatings. The 3D laser microscopic method yielded data based on micro-topographic information. The key benefits of the 3D confocal laser scanning microscope are the information on the mm-scale spatial distribution of coating thickness and bulk density. These additional parameters of the clod surface or aggregate micro-topography can be useful for improved quantification of accessibility of sorption surfaces and for describing macropore-matrix mass transfer of reactive solutes.
EGUGA, Apr 1, 2017
Isothermal and non-isothermal infiltration experiments with tracer breakthrough were carried out ... more Isothermal and non-isothermal infiltration experiments with tracer breakthrough were carried out in the laboratory on one intact column (18.9 cm in diameter, 25 cm in height) of sandy loam soil. For the isothermal experiment, the temperature of the infiltrating water was 20°C to the initial temperature of the sample. For the two non-isothermal experiments water temperature was set at 8°C and 6°C, while the initial temperature of the sample was 22°C. The experiments were conducted under the same initial and boundary conditions. Pressure heads and temperatures were monitored in two depths (8.8 and 15.3 cm) inside the soil sample. Two additional temperature sensors monitored the entering and leaving temperatures of the water. Water drained freely through the perforated plate at the bottom of the sample by gravity and outflow was measured using a tipping bucket flowmeter. The permeability of the sample calculated for steady state stages of the experiment showed that the significant difference between water flow rates recorded during the two experiments could not only be justified by temperature induced changes of the water viscosity and density. The observed data points of the breakthrough curve were successfully fitted using the two-region physical non-equilibrium model. The results of the breakthrough curves showed similar asymmetric shapes under isothermal and non-isothermal conditions.
EGU General Assembly Conference Abstracts, May 1, 2014
Journal of Environmental Engineering, Apr 1, 2019
AbstractCryptosporidia are opportunistic pathogens, some of which infect humans when ingested in ... more AbstractCryptosporidia are opportunistic pathogens, some of which infect humans when ingested in water or food. Filtration through granular media is the primary mechanism to remove them from water....
Freezing and thawing cycles in laboratory were studied. Freezing-thawing cycles were carried out ... more Freezing and thawing cycles in laboratory were studied. Freezing-thawing cycles were carried out in the laboratory on fully saturated packed sand sample (15 cm in diameter and 20 cm in height). Series of freezing-thawing cycles were conducted with newly designed experimental setup. The setup consisted of inner plastic tube covered on its sides and outer plastic tube. The column sample was placed into the precisely controlled freezer chamber. The top of the sample was covered by an aluminum lid. Initially the sample was equilibrated at +10 °C then the temperature inside the chamber was changed to -10 °C. The inner temperature of the sample was monitored in three depths by thin temperature sensors (109 SS, Campbell Scientific, USA) horizontally inserted into the sample. The experiment aims to provide information on freezing dynamics and thermo-mechanical changes during the freezing and thawing cycles. Horizontal gradient within freezing cycle was monitored. The data were compared with...
In this study, magnetic resonance imaging (MRI) was used to investigate the freezing and thawing ... more In this study, magnetic resonance imaging (MRI) was used to investigate the freezing and thawing process of a series of repacked samples of sand, soil, and sand-soil mixture. The samples were placed in a thermally insulated container inside a vertical bore MRI scanner and cooled by flowing cold gaseous nitrogen through a porous material at the top of the container. Temperatures were monitored in several points above the sample and at the sample surface, and a marker placed on the sample surface was used to measure sample deformation. A 4.7 T magnet was used for MRI and the Multiple-Slice Spin-Echo (MSME) and Zero Echo Time (ZTE) pulse sequences were employed to obtain the images. The contrast between the frozen and unfrozen water in the samples was given by the substantial difference in T1 and T2 relaxation times between the two states. The hydrogen in the frozen water does not produce any signal for both pulse sequences, thus all the signal represent the liquid/unfrozen water. The ...
AGU Fall Meeting Abstracts, Dec 1, 2018
EGU General Assembly Conference Abstracts, Apr 1, 2019