Sodium ion specific fluorescence labeled transparent soil sample as well as preparation method and application thereof

Abstract

The invention provides a sodium ion specific fluorescence labeled transparent soil sample as well as a preparation method and application thereof, and belongs to the technical field of rock soil and geological engineering. The method comprises the following steps: firstly, sequentially carrying out hydrophilization treatment, solvent evaporation and dissolution on a sodion combined benzofuran isophthalate probe to obtain a probe mother solution; mixing the probe mother solution, a buffer solution, an inorganic sodium salt solution and a solvent to prepare a fluorescence labeling pore solution; and finally, mixing the sodium polyacrylate particles and the fluorescence labeled pore liquid, and performing vacuum saturation treatment to obtain the transparent soil sample. The transparent soil sample provided by the invention still keeps excellent optical transparency while having sodium ion specific response capability, so that a stable and reliable experimental medium is provided for in-situ, real-time and full-field observation of sodium ion migration.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of geotechnical and geological engineering, and particularly relates to a sodium ion specific fluorescently labeled transparent soil sample and a preparation method and application thereof. BACKGROUND

[0002] The migration, enrichment and precipitation of internal ions of saline soil, especially sulfate saline soil, are core factors inducing engineering diseases such as salt heaving and dissolution subsidence. Therefore, in-situ, real-time and visualized tracking of the ion migration behavior in soil is crucial for revealing the mechanism of saline soil engineering diseases.

[0003] Currently, two major technical bottlenecks exist in the field of research: firstly, the traditional research method (such as chemical analysis in the laboratory after drilling sampling) is destructive. This method cannot continuously observe the same sample, destroys the original structure and stress state of the soil, and can only obtain discrete spatiotemporal data, making it difficult to capture the whole process of ion migration dynamics and greatly limiting the in-depth understanding of the mechanism; secondly, the emerging transparent soil technology has functional limitations. This technology successfully realizes the visualization of internal displacement and seepage of geotechnical media through the principle of refractive index matching, but its functions mainly focus on physical and mechanical processes, and it lacks the ability to track the migration of specific ions, especially chemical fields, which cannot meet the urgent needs of ion migration visualization in saline soil research.

[0004] The introduction of fluorescent probe technology into the transparent soil system can provide a solution for ion migration visualization. In theory, sodium ion specific fluorescent probe, i.e., Sodium-Binding Benzofuran Isophthalate (SBFI), has high selectivity for sodium ions and can effectively distinguish potassium ions with similar properties. When combined with sodium ions, the peak of the fluorescence excitation spectrum of SBFI moves, and by measuring the fluorescence intensity ratio at different excitation wavelengths (ratiometric method), quantitative measurement of sodium ions can be achieved.

[0005] However, the existing transparent soil technology using fused quartz sand or nano-silica as solid particles has a corresponding pore fluid mainly composed of oil-based mixed liquid of white oil and n-dodecane, which cannot dissolve salt. The existing technology has double defects in the study of sodium ion migration behavior of soil. On the observation method level, the traditional destructive sampling technology cannot continuously observe the same sample, but only obtains discrete and non-in-situ static data, which is difficult to reveal the dynamic whole process of ion migration; on the sample material level, although the conventional transparent soil technology solves the problem of visualization of physical process, it is single in function and does not have chemical tracing ability. If the commercially available sodium ion fluorescent probe (such as SBFI) is directly introduced into the conventional transparent soil system, serious light scattering will be caused due to the mismatch of the refractive index of the required water-based solvent of the probe and the transparent solid particles such as fused quartz sand or nano-silica commonly used, which will destroy the optical transparency of the material and make the visualization observation impossible. This "refractive index mismatch" problem is the core technical obstacle to realize the visualization of chemical field. Therefore, it is urgent to break through the functional limitations of the existing transparent soil technology and develop a preparation method of transparent soil sample which can not only maintain excellent optical transparency but also have specific fluorescent response to sodium ions, which is of great significance to realize the in-situ, real-time and quantitative visualization of sodium ion migration. SUMMARY

[0006] The purpose of the present application is to provide a sodium ion specific fluorescently labeled transparent soil sample and its preparation method and application, so as to solve the problem that the existing transparent soil cannot reflect salt and is prone to optical failure after introducing a chemical probe.

[0007] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions: The present application provides a preparation method of a sodium ion specific fluorescently labeled transparent soil sample, comprising the following steps: (1) sequentially performing hydrophilization treatment, solvent evaporation and dissolution on SBFI to obtain a probe mother liquor; (2) mixing the probe mother liquor, a buffer solution, an inorganic sodium salt solution and a solvent to prepare a fluorescently labeled pore fluid; (3) mixing polyacrylic acid sodium particles (SAP) and the fluorescently labeled pore fluid and then performing vacuum saturation treatment to obtain a transparent soil sample.

[0008] Preferably, in step (1), the hydrophilic modifier used in the hydrophilization treatment is dichloromethane and trifluoroacetic acid.

[0009] Preferably, in step (1), the hydrophilization treatment is performed for 2-12 h.

[0010] Preferably, in step (2), the buffer solution is a phosphoric acid-tetramethylammonium hydroxide buffer solution; the concentration of SBFI in the fluorescently labeled pore solution is 8-12 μmol / L; and the pH of the fluorescently labeled pore solution is 7.5-8.0.

[0011] Preferably, in steps (2) and (3), the refractive index of the fluorescently labeled pore solution is consistent with the refractive index of the water-saturated sodium polyacrylate particles.

[0012] Preferably, in step (3), the mass-to-volume ratio of the SAP and the fluorescently labeled pore solution is 10-15 g:1 L.

[0013] Preferably, in step (3), the vacuum degree during the vacuum saturation treatment is -100 kPa.

[0014] Preferably, in step (3), the time for the vacuum saturation treatment is 3-6 h.

[0015] The application also provides a sodium ion-specific fluorescently labeled transparent soil sample prepared by the method for preparing a sodium ion-specific fluorescently labeled transparent soil sample.

[0016] The application also provides a use of the sodium ion-specific fluorescently labeled transparent soil sample in the migration of salt ions in simulated saline soil.

[0017] The application has the following beneficial effects: The application creatively combines fluorescent probe technology with transparent soil technology, and successfully prepares a fluorescently labeled transparent soil sample capable of specifically tracing the migration of sodium ions, thereby breaking through the limitation of existing transparent soil technology that can only be used for physical field visualization. The core effect is that, by precisely designing a pore solution formula and controlling a refractive index, the problem that conventional transparent soil cannot reflect salt content and that the introduction of a chemical probe easily leads to optical failure is solved, so that the sample still maintains excellent optical transparency while having the ability to specifically respond to sodium ions, thereby providing a stable and reliable experimental medium for in-situ, real-time and full-field observation of the migration of sodium ions. This not only significantly improves the depth and precision of the study of the water and salt migration mechanism of saline soil, and eliminates the limitation of traditional destructive sampling, but also establishes a technical idea for a standardized preparation process, has good repeatability and expandability, and opens up a new way for the visualization of chemical processes in geotechnical engineering. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 A flowchart for preparing a sodium ion-specific fluorescently labeled transparent soil sample. DETAILED DESCRIPTION

[0019] The application provides a method for preparing a sodium ion-specific fluorescently labeled transparent soil sample, which comprises the following steps: (1) sequentially carrying out hydrophilic treatment, evaporating solvent, dissolving on the SBFI to obtain a probe mother liquor; (2) mixing the probe mother liquor, a buffer solution, an inorganic sodium salt solution and a solvent to prepare a fluorescently labeled pore solution; (3) mixing the SAP and the fluorescently labeled pore solution and then carrying out vacuum saturation treatment to obtain a transparent soil sample.

[0020] In the present application, in step (1), the hydrophilic modifier used in the hydrophilic treatment is dichloromethane and trifluoroacetic acid.

[0021] In the present application, in step (1), the hydrophilic treatment is carried out for 2-12 h, 2.5 h, 3 h, 4 h, 5 h, 6 h, 8 h or 10 h.

[0022] In the present application, the specific process of the hydrophilic treatment is as follows: mixing the SBFI, dichloromethane and trifluoroacetic acid and then carrying out magnetic stirring to complete the hydrophilic process.

[0023] In the present application, the mass-volume ratio of the SBFI, dichloromethane and trifluoroacetic acid is 10-30 mg:5-15 mL:5-15 mL, preferably 15-25 mg:8-12 mL:8-12 mL, and more preferably 20 mg:10 mL:10 mL.

[0024] In the present application, the purpose of the hydrophilic treatment is to effectively improve the hydrophilicity of the probe, so that the probe can be dissolved in ultrapure water and the sensitivity of subsequent labeling can be ensured.

[0025] In the present application, the specific step of evaporating the solvent is as follows: evaporating the solvent from the mixture after the hydrophilic treatment by heating, and preferably heating at a temperature below 100℃ until the solvent is completely evaporated. The purpose of evaporation is to remove the solvent and the byproduct isobutene to obtain a water-soluble SBFI derivative. The water-soluble SBFI derivative has a solubility in water of ≥1 mmol / L, and the fluorescence response performance to Na ＋ is retained by ≥80%.

[0026] In the present application, the water-soluble SBFI derivative obtained after the evaporation of the solvent is dissolved in dimethyl sulfoxide (DMSO) to obtain a probe mother liquor, and the concentration of the probe mother liquor is 8-12 mg / mL, preferably 10 mg / mL.

[0027] In the present application, in step (2), the buffer solution is a phosphoric acid-tetramethylammonium hydroxide buffer solution; in the fluorescently labeled pore solution, the concentration of SBFI is 8-12 μmol / L; and the pH of the fluorescently labeled pore solution is 7.5-8.0.

[0028] In the present application, Na +The fluorescent probe is stabilized in an acidic or alkaline environment of pH 7.2 to 8.0. To avoid interference from other cations, a tetramethylammonium hydroxide phosphate buffer solution is selected.

[0029] In this invention, the preparation method of the phosphate-tetramethylammonium hydroxide buffer solution is as follows: mix the phosphate aqueous solution and water, add the tetramethylammonium hydroxide solution (TMAH) under ice bath conditions, mix evenly to make the pH of the mixed solution 7.5±0.1, and finally adjust the volume and store it.

[0030] In this invention, the buffer solution provides a stable working environment for SBFI. In the presence of 1 μmol / L SBFI, the pH drift is <0.02 and the fluorescence background drift is <1% within 24 hours.

[0031] In this invention, the inorganic sodium salt solution is preferably a sodium sulfate solution; the concentration of the inorganic sodium salt solution can be determined according to the salt content of the soil with different degrees of salinization. In the embodiments of this invention, the concentration of the sodium sulfate solution is preferably 0.028~0.042 mol / L, more preferably 0.0352 mol / L.

[0032] In this invention, the volume ratio of the sodium sulfate solution to the fluorescently labeled pore liquid is 8~12mL:1L, preferably 9~11mL:1L, and more preferably 10mL:1L.

[0033] In this invention, in step (2), the solvent is a mixture of methanol and water, wherein the volume ratio of methanol to water is 3:5. Methanol, as a co-solvent, can improve the solubility and stability of SBFI in water-based porous liquids.

[0034] The use of a methanol-water mixed solvent in this invention facilitates further dispersion and stability of the probe. Precise control of the refractive index is a crucial step in ensuring the matching of the fluorescently labeled pore liquid with the SAP particles and achieving optical transparency in the final transparent soil sample.

[0035] In this invention, in steps (2) and (3), the refractive index of the fluorescently labeled pore liquid is consistent with the refractive index of the water-saturated SAP particles.

[0036] In this invention, after the SAP particles are saturated with water, the refractive index is tested using an Abbe refractometer. The refractive index is approximately 1.33, which is close to the refractive index of water, thus giving the sample optical transparency.

[0037] In this invention, the SAP particles have a particle size of 60-200 mesh.

[0038] In this invention, in step (3), the mass-to-volume ratio of the SAP particles and the fluorescently labeled pore liquid is 10-15 g:1 L, preferably 12-14 g:1 L, and more preferably 12.8 g:1 L.

[0039] In this invention, in step (3), the vacuum degree during the vacuum saturation treatment is -100 kPa.

[0040] In this invention, in step (3), the vacuum saturation treatment time is 3~6h, preferably 4~5h.

[0041] In this invention, the vacuum saturation process ensures that the fluorescently labeled pore liquid completely fills the interparticle pores, forming a uniform, defect-free, transparent soil sample.

[0042] The present invention also provides a sodium ion-specific fluorescently labeled transparent soil sample prepared by the above-described method for preparing a sodium ion-specific fluorescently labeled transparent soil sample.

[0043] The present invention also provides an application of the above-described sodium ion-specific fluorescently labeled transparent soil sample in the migration of salt ions in simulated saline soil.

[0044] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0045] Example 1

[0046] After the SAP (particle size range of 60~200 mesh) was saturated with water, its refractive index was measured using an Abbe refractometer. The refractive index was approximately 1.33, which was taken as the target refractive index.

[0047] The objective is to prepare a 1L transparent soil sample. The specific process is as follows: Preparation of probe stock solution: Weigh 20 mg of SBFI (manufacturer: Tianjin Xiens Biochemical Technology Co., Ltd.), mix with 10 mL of dichloromethane and 10 mL of trifluoroacetic acid, and stir magnetically for 2.5 h at room temperature to hydrophilize the mixture. Then transfer the mixture to a glass petri dish and heat it in a water bath at 100 °C until the solvent is completely evaporated. The viscous substance adhering to the bottom of the petri dish is the water-soluble SBFI derivative. Dissolve the water-soluble SBFI derivative in 10 mL of DMSO to obtain the probe stock solution with a concentration of 10 mg / mL.

[0048] Preparation of phosphate-tetramethylammonium hydroxide buffer solution: Measure 1.5 mL of phosphoric acid (H3PO4, concentration 85% w / w, density 1.69 g / mL) and dilute with 800 mL of deionized water, stirring until homogeneous; under ice bath conditions, add 28.0 mL of TMAH solution (concentration 25%) to the diluted phosphoric acid solution and stir until homogeneous using a magnetic stirrer (800 rpm); monitor the pH value of the solution using a pH meter, and continue to slowly add tetramethylammonium hydroxide (TMAH, concentration 25%) dropwise to the mixed solution until the pH of the solution is 7.5 ± 0.1; bring the volume to 1 L with deionized water; store at 4℃.

[0049] Preparation of fluorescently labeled pore solution: Measure 10 mL of 0.0352 mol / L sodium sulfate solution and add a calculated volume of SBFI stock solution (to bring the final SBFI concentration in the fluorescently labeled pore solution to 10 μmol / L), and gently shake to mix. Then, add this mixture to a mixed solvent of methanol and ultrapure water (volume ratio 3:5), and add a prepared tetramethylammonium hydroxide phosphate buffer solution to stabilize the pH of the fluorescently labeled pore solution at 7.5–8.0. Make up to 1 L and ultrasonically disperse for 10 min. Finally, measure the refractive index of the solution using an Abbe refractometer and finely adjust by adding ultrapure water until the refractive index matches that of water-saturated SAP (target refractive index 1.333), thus obtaining the fluorescently labeled pore solution.

[0050] Weigh 12.8g of dried SAP particles (particle size range 60~200 mesh) and loosely pack them into a 1L custom-made transparent soil model box. Then, slowly and evenly pour the 1L of fluorescently labeled pore liquid into the model box and mix thoroughly with the SAP particles. After sealing the model box, place it in a vacuum drying oven, evacuate it (vacuum degree -100kPa) and maintain it for 4 hours to completely remove air bubbles from the system and promote full saturation of the SAP particles. Let it stand until the SAP particles have completely absorbed the pore liquid and expanded and formed, thus obtaining a transparent soil sample.

[0051] The transparent soil sample prepared in Example 1 exhibited a homogeneous, transparent gel solid state, indicating that the SAP particles had fully absorbed water and swelled with good refractive index matching. In a darkroom environment, when the sample was irradiated with an ultraviolet excitation source with a center wavelength of 470 nm, a uniform yellow fluorescence with a wavelength of 560 nm was observed throughout the sample. The intensity of this fluorescence signal showed a quantitative relationship with the sodium ion concentration in the pore fluid, which could be calibrated using ratiometric methods, thereby enabling quantitative tracking of the sodium ion migration process.

[0052] Example 2

[0053] After the SAP (particle size range of 60~200 mesh) was saturated with water, its refractive index was measured using an Abbe refractometer. The refractive index was approximately 1.33, which was taken as the target refractive index.

[0054] The objective is to prepare a 1L transparent soil sample. The specific process is as follows: Preparation of probe stock solution: Weigh 20 mg of SBFI (manufacturer: Tianjin Xiens Biochemical Technology Co., Ltd.), mix with 10 mL of dichloromethane and 10 mL of trifluoroacetic acid, and stir magnetically for 8 h at room temperature to hydrophilize the mixture. Then transfer the mixture to a glass petri dish and heat it in a 100°C water bath until the solvent is completely evaporated. The viscous substance adhering to the bottom of the petri dish is the water-soluble SBFI derivative. Dissolve the water-soluble SBFI derivative in 10 mL of DMSO to obtain the probe stock solution with a concentration of 8 mg / mL.

[0055] Preparation of phosphate-tetramethylammonium hydroxide buffer solution: Measure 1.5 mL of phosphoric acid (H3PO4, concentration 85% w / w, density 1.69 g / mL) and dilute with 800 mL of deionized water, stirring until homogeneous; under ice bath conditions, add 28.0 mL of TMAH solution (concentration 25%) to the diluted phosphoric acid solution and stir until homogeneous using a magnetic stirrer (800 rpm); monitor the pH value of the solution using a pH meter, and continue to slowly add tetramethylammonium hydroxide (TMAH, concentration 25%) dropwise to the mixed solution until the pH of the solution is 7.5 ± 0.1; bring the volume to 1 L with deionized water; store at 4℃.

[0056] Preparation of fluorescently labeled pore solution: Measure 10 mL of 0.0352 mol / L sodium sulfate solution and add a calculated volume of SBFI stock solution (to achieve a final SBFI concentration of 8 μmol / L in the fluorescently labeled pore solution), and gently shake to mix. Then, add this mixture to a mixed solvent of methanol and ultrapure water (volume ratio 3:5), and add a prepared tetramethylammonium hydroxide phosphate buffer solution to stabilize the pH of the fluorescently labeled pore solution at 7.5–8.0. Make up to 1 L and ultrasonically disperse for 10 min. Finally, measure the refractive index of the solution using an Abbe refractometer and finely adjust by adding ultrapure water until the refractive index matches that of water-saturated SAP (target refractive index 1.333), thus obtaining the fluorescently labeled pore solution.

[0057] Weigh 12.8g of dried SAP particles (particle size range 60~200 mesh) and loosely pack them into a 1L custom-made transparent soil model box. Then, slowly and evenly pour the 1L of fluorescently labeled pore liquid into the model box and mix thoroughly with the SAP particles. After sealing the model box, place it in a vacuum drying oven, evacuate it (vacuum degree -100kPa) and maintain it for 3 hours to completely remove air bubbles from the system and promote full saturation of the SAP particles. Let it stand until the SAP particles have completely absorbed the pore liquid and expanded and formed, thus obtaining a transparent soil sample.

[0058] Example 3

[0059] After the SAP (particle size range of 60~200 mesh) was saturated with water, its refractive index was measured using an Abbe refractometer. The refractive index was approximately 1.33, which was taken as the target refractive index.

[0060] The objective is to prepare a 1L transparent soil sample. The specific process is as follows: Preparation of probe stock solution: Weigh 20 mg of SBFI (manufacturer: Tianjin Xiens Biochemical Technology Co., Ltd.), mix with 10 mL of dichloromethane and 10 mL of trifluoroacetic acid, and stir magnetically for 12 h at room temperature to perform hydrophilization treatment. Then transfer the mixture to a glass petri dish and heat it in a water bath at 100 °C until the solvent is completely evaporated. The viscous substance adhering to the bottom of the petri dish is the water-soluble SBFI derivative. Dissolve the water-soluble SBFI derivative in 10 mL of DMSO to obtain the probe stock solution with a concentration of 12 mg / mL.

[0061] Preparation of phosphate-tetramethylammonium hydroxide buffer solution: Measure 1.5 mL of phosphoric acid (H3PO4, concentration 85% w / w, density 1.69 g / mL) and dilute with 800 mL of deionized water, stirring until homogeneous; under ice bath conditions, add 28.0 mL of TMAH solution (concentration 25%) to the diluted phosphoric acid solution and stir until homogeneous using a magnetic stirrer (800 rpm); monitor the pH value of the solution using a pH meter, and continue to slowly add tetramethylammonium hydroxide (TMAH, concentration 25%) dropwise to the mixed solution until the pH of the solution is 7.5 ± 0.1; bring the volume to 1 L with deionized water; store at 4℃.

[0062] Preparation of fluorescently labeled pore solution: Measure 10 mL of 0.0352 mol / L sodium sulfate solution and add a calculated volume of SBFI stock solution (to achieve a final SBFI concentration of 12 μmol / L in the fluorescently labeled pore solution), and gently shake to mix. Then, add this mixture to a mixed solvent of methanol and ultrapure water (volume ratio 3:5), and add a prepared tetramethylammonium hydroxide phosphate buffer solution to stabilize the pH of the fluorescently labeled pore solution at 7.5–8.0. Make up to 1 L and ultrasonically disperse for 10 min. Finally, measure the refractive index of the solution using an Abbe refractometer and finely adjust by adding ultrapure water until the refractive index matches that of water-saturated SAP (target refractive index 1.333), thus obtaining the fluorescently labeled pore solution.

[0063] Weigh 12.8g of dried SAP particles (particle size range 60~200 mesh) and loosely pack them into a 1L custom-made transparent soil model box. Then, slowly and evenly pour the 1L of fluorescently labeled pore liquid into the model box and mix thoroughly with the SAP particles. After sealing the model box, place it in a vacuum drying oven, evacuate it (vacuum degree -100kPa) and maintain it for 6 hours to completely remove air bubbles from the system and promote full saturation of the SAP particles. Let it stand until the SAP particles have completely absorbed the pore liquid and expanded to form a transparent soil sample.

[0064] This invention successfully prepared a transparent soil sample with optical transparency and sodium ion-specific fluorescence properties, providing a qualified material basis for subsequent visualization observation experiments.

[0065] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a sodium ion-specific fluorescently labeled transparent soil sample, characterized in that, Includes the following steps: (1) The sodium ion-bound benzofuran isophthalate probe was sequentially hydrophilized, the solvent was evaporated, and it was dissolved to obtain the probe mother solution; (2) Mix the probe stock solution, buffer solution, inorganic sodium salt solution and solvent to prepare fluorescently labeled pore solution; (3) After mixing sodium polyacrylate particles and fluorescently labeled pore liquid, vacuum saturation treatment was performed to obtain transparent soil samples.

2. The method for preparing sodium ion-specific fluorescently labeled transparent soil samples according to claim 1, characterized in that, In step (1), the hydrophilic modifiers used in the hydrophilic treatment are dichloromethane and trifluoroacetic acid.

3. The method for preparing sodium ion-specific fluorescently labeled transparent soil samples according to claim 2, characterized in that, In step (1), the hydrophilization treatment takes 2 to 12 hours.

4. The method for preparing sodium ion-specific fluorescently labeled transparent soil samples according to any one of claims 1 to 3, characterized in that, In step (2), the buffer solution is a tetramethylammonium hydroxide phosphate buffer solution; the concentration of sodium ions binding to the benzofuran isophthalic acid ester probe in the fluorescently labeled pore liquid is 8~12 μmol / L; and the pH value of the fluorescently labeled pore liquid is 7.5~8.

0.

5. The method for preparing sodium ion-specific fluorescently labeled transparent soil samples according to claim 1, characterized in that, In steps (2) and (3), the refractive index of the fluorescently labeled pore liquid is consistent with the refractive index of the water-saturated sodium polyacrylate particles.

6. The method for preparing sodium ion-specific fluorescently labeled transparent soil samples according to claim 3 or 5, characterized in that, In step (3), the mass-to-volume ratio of the sodium polyacrylate particles and the fluorescently labeled pore liquid is 10~15g:1L.

7. The method for preparing sodium ion-specific fluorescently labeled transparent soil samples according to claim 6, characterized in that, In step (3), the vacuum degree during the vacuum saturation treatment is -100 kPa.

8. The method for preparing sodium ion-specific fluorescently labeled transparent soil samples according to claim 5 or 7, characterized in that, In step (3), the vacuum saturation treatment time is 3~6h.

9. A sodium ion-specific fluorescently labeled transparent soil sample prepared by the method for preparing sodium ion-specific fluorescently labeled transparent soil sample according to any one of claims 1 to 8.

10. The application of the sodium ion-specific fluorescently labeled transparent soil sample according to claim 9 in the migration of salt ions in simulated saline soil.

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