Simulation test method for migration of metal ions in soil

Abstract

The invention aims to provide a simulation test method for migration of metal ions in soil, and relates to the technical field of soil heavy metal content detection. The simulation test method for migration of the metal ions in the soil comprises the following steps: acquiring a ground surface two-dimensional plane image of a to-be-evaluated region shot by image acquisition equipment, delimiting a sampling boundary line and a sampling point, and determining latitude and longitude coordinates; vertically sampling, recording relative position information of a sampling point, and carrying out initial metal ion concentration detection on the primary soil sample; stacking and combining to form a simulation sample; dropwise adding a preset volume of clear water or a metal ion solution at any position of the top of the simulated sample to carry out metal ion migration simulation, cutting, and carrying out initial metal ion concentration detection on the secondary soil sample; and comparing data. The method has the characteristics of low implementation difficulty, relatively low cost and freely selectable sample period, and the migration simulation result can provide effective reference for treatment of metal ions in soil.

Description

Technical Field

[0001] The present invention relates to the technical field of soil heavy metal content detection, and in particular to a simulation test method for metal ion migration in soil. Background Art

[0002] With the continuous acceleration of industrialization and the continuous growth of population, heavy metal pollution such as lead, copper and zinc has become a global problem. With the increasing mining, smelting, processing and commercial manufacturing activities of heavy metals, sudden heavy metal pollution accidents in water caused by accidental leakage and illegal discharge occur from time to time. Heavy metals are highly toxic, difficult to be metabolized in the environment, easily enriched by organisms and have biological magnification effects. They not only pollute the water environment, but also seriously threaten the survival of humans and aquatic organisms. It is particularly important to effectively and accurately detect the concentration of heavy metals.

[0003] According to the National Soil Pollution Survey Bulletin (2014) of the Ministry of Environmental Protection, the national soil pollution rate exceeded the standard by 16.1%, of which the proportion of severely polluted points was 1.1%; the national cultivated land soil point exceeded the standard by 19.4%, and the heavy metal cadmium exceeded the standard by 7%. The survey results show that heavy metal pollution accounts for a considerable proportion of soil pollution in my country, and the pollution is serious and urgently needs to be treated. Therefore, it is self-evident that it is important to understand the migration and transformation process of heavy metal ions in the soil for the treatment of polluted soil.

[0004] At present, studying the migration and transformation process of heavy metals in soil through field experiments is not only difficult and costly, but also has a long test cycle, which cannot meet the urgency of the current stage of soil contamination treatment. Summary of the invention

[0005] The present invention aims to provide a simulation test method for metal ion migration in soil, which has the characteristics of low implementation difficulty, relatively low cost, and freely selectable sample cycle, and the simulation migration results can provide an effective reference for the treatment of metal ions in soil.

[0006] The technical solution adopted by the present invention is: A simulation test method for metal ion migration in soil comprises the following steps: Step S1, obtaining a two-dimensional plane image of the surface of the area to be evaluated taken by an image acquisition device, and delineating a sampling boundary line and sampling points on the two-dimensional plane image of the surface; the sampling points are distributed on the sampling boundary line and in the area surrounded by the sampling boundary line; according to the pixel coordinates of the sampling points in the two-dimensional plane image of the surface, determining the longitude and latitude coordinates corresponding to the sampling points; Step S2, performing vertical sampling in the area to be evaluated according to the latitude and longitude coordinates of the sampling points determined in step S1, recording the relative position information of each sampling point, and performing initial metal ion concentration detection on the primary soil sample collected at each sampling point; Step S3, the primary soil samples collected from all the sampling points are arranged vertically. After determining the geometric center of the figure formed by the sampling boundary lines on the two-dimensional plane image of the ground surface, the primary soil sample collected from the sampling point closest to the geometric center is used as the vertical stacking center, and the primary soil samples collected from the remaining sampling points are moved closer to the vertical stacking center according to the relative position information of each sampling point recorded in step S2 and the distance from the vertical stacking center, and are stacked and combined to form a simulated sample with no gaps and a flush bottom surface, and the side walls of the simulated sample are wrapped with plastic film; wherein, if there are still gaps after the adjacent primary soil samples are brought close to each other and in contact, the same soil with known metal ion types and concentrations is used to fill them; Step S4, dripping a preset volume of clean water or metal ion solution at any position on the top of the simulated sample formed in step S3, and after reaching a preset simulation time, dividing the simulated sample according to the position when it was stacked and combined in step S3, and re-dividing it into secondary soil samples corresponding to the primary soil samples collected at each sampling point, and then performing metal ion concentration detection on the secondary soil samples; Step S5, comparing the changes in metal ion concentrations of the primary soil sample and the corresponding secondary soil sample collected at the same sampling point, to obtain metal ion migration simulation test data.

[0007] Furthermore, the steps S1 to S5 are repeatedly performed 1 to 5 times; wherein, during the repeated execution, the sampling points are reselected; or, part or all of the sampling points selected later are located near the corresponding sampling points selected for the first time.

[0008] Furthermore, the image acquisition device used in step S1 is a camera, and the specific process of determining the longitude and latitude coordinates corresponding to the sampling point according to the pixel coordinates of the sampling point in the two-dimensional plane image of the ground surface taken by the camera is as follows: Step SA11, establishing a camera overlooking coordinate system; Step SA12, calculating the distance coordinates (cx, cy) of the pixel coordinates (px, py) of the sampling points in the x-direction and the y-direction in the camera's top-view coordinate system one by one; Step SA13, calculating the coordinate position (ex,ey) of the pixel coordinate (px,py) in the ground coordinate system with the camera as the origin according to the distance coordinate (cx,cy); Step SA14, calculating the longitude and latitude coordinates (ex_long, ex_lat) corresponding to the pixel coordinates (px, py) according to the longitude and latitude coordinates (camera_long, camera_lat) of the camera itself and the coordinate position (ex, ey).

[0009] Furthermore, the image acquisition device used in step S1 is an aerial photography drone, and the specific process of determining the longitude and latitude coordinates corresponding to the sampling point according to the pixel coordinates of the sampling point in the two-dimensional plane image of the surface taken by the aerial photography drone is as follows: Step SB11, the aerial photography drone acquires at least three consecutive aerial images; any one of the aerial images is used as the two-dimensional plane image of the ground surface for demarcating the sampling boundary line and the sampling point; Step SB12, using SIFT algorithm and the aerial image to construct a pixel coordinate and GPS coordinate conversion model; Step SB13, obtain the pixel coordinates (px, py) of the sampling points one by one, and input the pixel coordinates (px, py) into the pixel coordinate and GPS coordinate conversion model to calculate the real GPS coordinates, and output the longitude and latitude coordinates (ex_long, ex_lat) corresponding to the pixel coordinates (px, py).

[0010] Furthermore, in the vertical sampling in step S2, a sampling tube with a polygonal or circular cross section is used.

[0011] Furthermore, before vertical sampling is performed in step S2, the altitude value of each sampling point is first determined, and the altitude values ​​are sorted from high to low, and then the sampling point corresponding to the highest altitude value is selected as the reference sampling point for vertical sampling, and the remaining sampling points are vertically sampled based on the corresponding altitude values ​​and the reference sampling point as a reference, to ensure that the position points deepest to the ground surface are roughly coplanar when all the sampling points are vertically sampled.

[0012] Furthermore, the initial metal ion concentration detection of the primary soil sample in step S3 includes the following process: Step S31, firstly divide the primary soil sample collected at the reference sampling point into n soil sampling test areas along the height direction of the primary soil sample, each soil sampling test area having the same height, and then obtain a suitable amount of soil from each soil sampling test area to perform metal ion concentration detection; Step S32, for the primary soil samples collected at the remaining sampling points, refer to the same method as the reference sampling point, divide the soil sampling test areas with equal heights from bottom to top, and obtain a suitable amount of soil for metal ion concentration detection; if the top of the primary soil sample fails to form a complete soil sampling test area, no metal ion concentration detection is performed, or it is still recorded as the soil sampling test area and metal ion concentration detection is performed.

[0013] Furthermore, when the metal ion concentration of the secondary soil sample is detected in step S5, it is performed with reference to step S31 and step S32.

[0014] Furthermore, the simulated sample prepared in step 3 is first placed in an environment with a temperature of 25±1° C. and a humidity of 40±1% RH for 1 to 10 days before subsequent testing.

[0015] Furthermore, after the metal ion concentration test is completed for the secondary soil sample in step S4, it is stacked and combined again with reference to step S3 to form a secondary simulation sample, and then the metal ion concentration test is performed again with reference to step S4, and finally the metal ion migration simulation test data is obtained with reference to step 5.

[0016] The beneficial effects of the present invention are: The present invention provides a simulation test method for metal ion migration in soil, which forms a simulation sample that is relatively close to the topography of the area to be evaluated by a specific sampling method, then performs metal ion migration simulation on the simulation sample, and finally compares the change in metal ion concentration before and after the simulation to obtain metal ion migration simulation test data, which can be used for the soil situation in the area to be evaluated. The simulation test method is easy to implement and relatively low in cost, the test cycle can be freely selected, and the simulation migration results can provide an effective reference for the treatment of metal ions in soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 The figure in the figure is a two-dimensional surface image of a region to be evaluated.

[0019] Figure 2 A two-dimensional plane image of the ground surface after delineating the sampling boundary line and sampling points.

[0020] Figure 3This is a top view of the simulated test specimen formed by a single stacking of soil samples.

[0021] Figure 4 This is a schematic diagram of the three-dimensional space effect model.

[0022] Figure 5 Schematic diagram of repeated sampling locations.

[0023] Figure 6 Schematic diagram of vertical sampling effect.

[0024] Figure 7 This is a schematic diagram of the soil sampling and testing area division. DETAILED DESCRIPTION

[0025] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0026] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention.

[0027] The embodiments of the invention are described in detail below with reference to the accompanying drawings.

[0028] A simulation test method for metal ion migration in soil comprises the following steps: Step S1, obtaining a two-dimensional surface plane image of the area to be evaluated taken by an image acquisition device, and delineating sampling boundary lines and sampling points on the two-dimensional surface plane image; the sampling points are distributed on the sampling boundary lines and in the area surrounded by the sampling boundary lines; and the longitude and latitude coordinates corresponding to the sampling points are determined according to the pixel coordinates of the sampling points in the two-dimensional surface plane image.

[0029] The sampling boundary line can be set randomly or according to test requirements, surface morphology and other factors. Figure 1 The figure shows a two-dimensional surface image of a region to be evaluated. After the sampling boundary line and sampling points are delineated on the two-dimensional surface image, Figure 2As shown in ; the sampling boundary line is a solid black line, which forms a pentagon after enclosing. There are 18 sampling points in total, marked as 1#~18#.

[0030] Step S2, vertical sampling is performed in the area to be evaluated according to the latitude and longitude coordinates of the sampling points determined in step S1, and the relative position information of each sampling point is recorded, and the initial metal ion concentration is detected for the primary soil sample collected from each sampling point.

[0031] In the step S2, a sampling tube with a polygonal or circular cross section is used for vertical sampling. For example, a sampling tube with a triangular or square cross section. Compared with a sampling tube with a circular cross section, a primary soil sample collected by a sampling tube with a polygonal cross section also presents a regular prism shape. When adjacent primary soil samples are stacked together, they are in a face-to-face contact manner, leaving fewer gaps, or even no gaps, and only a small amount of soil or no soil is needed for subsequent filling.

[0032] Step S3, the primary soil samples collected from all the sampling points are arranged vertically. After determining the geometric center of the figure formed by the sampling boundary lines on the two-dimensional plane image of the surface, the primary soil sample collected from the sampling point closest to the geometric center is used as the vertical stacking center, and the primary soil samples collected from the remaining sampling points are moved closer to the vertical stacking center according to the relative position information of each sampling point recorded in step S2 and the size of the distance from the vertical stacking center, and are stacked and combined to form a simulated sample with no gaps and a flush bottom surface, and the side walls of the simulated sample are wrapped with plastic film; wherein, if there are still gaps after the adjacent primary soil samples are brought close to each other and in contact, they are filled with the same soil with known metal ion types and concentrations.

[0033] The simulated sample prepared in step 3 is first placed in an environment with a temperature of 25±1°C and a humidity of 40±1%RH for 1 to 10 days before subsequent testing. In this embodiment, the simulated sample is stored in a specific environment for a certain period of time, which is conducive to stabilizing its internal structure, thereby improving the accuracy of the simulation.

[0034] For example, a sampling tube with a square cross section is used for vertical sampling. Figure 2 The 7# sampling point is closest to the geometric center of the pentagon, and the other 1#~6# sampling points and 8#~18# sampling points are close to the 7# sampling point according to their relative position information. The top view of the simulated sample formed by the stacking combination of the soil samples collected from the 1#~18# sampling points is as follows: Figure 3 as shown in .

[0035] Step S4, dripping (for example, 3 drops / min) a preset volume (for example, 1L) of clean water or metal ion solution at any position on the top of the simulated sample formed in the step S3, and after reaching a preset simulation time (for example, 48h), dividing the simulated sample according to the position when it was stacked and combined in the step S3, and redividing it into secondary soil samples corresponding to the primary soil samples collected at each sampling point, and then testing the metal ion concentration of the secondary soil samples.

[0036] The migration of metal ions in the soil is mostly accompanied by the migration of water. When using clean water for testing in this embodiment, the migration of the original metal ions in the soil can be simulated, which can reflect the degree to which the original metal ions are affected by the migration of water; using a metal ion solution such as a zinc chloride solution with a mass concentration of 5%, the migration of exogenous metal ions in the soil can be simulated. The specific choice of clean water or metal ion solution can be selected according to needs, and is not specifically limited in this embodiment. For example Figure 3 The simulated sample shown in the figure is divided into 18 secondary soil samples according to the stacking positions in step S3.

[0037] Step S5, comparing the changes in metal ion concentrations of the primary soil sample and the corresponding secondary soil sample collected at the same sampling point, to obtain metal ion migration simulation test data.

[0038] For example, the pixel coordinates of the sampling point are used as the X-axis and Y-axis coordinates, and the metal ion concentration is used as the Z-axis coordinate, and a three-dimensional coordinate diagram of the spatial distribution can be drawn. After smoothing, a similar Figure 4 The schematic diagram of the three-dimensional spatial effect model is shown in FIG. By comparing the schematic diagram of the three-dimensional spatial effect model after the two metal ion concentration tests, the change area and migration direction of the corresponding metal ions can be observed, which can provide an effective reference for the treatment of metal ions in the soil.

[0039] In the simulation test method for metal ion migration in soil in this embodiment, a simulation sample that is relatively close to the topography of the area to be evaluated is formed by a specific sampling method, and then a metal ion migration simulation is performed on the simulation sample. Finally, the change in metal ion concentration before and after the simulation can be compared to obtain metal ion migration simulation test data, which can be used for the soil situation in the area to be evaluated. This simulation test method is easy to implement and relatively low in cost. The sample cycle can be freely selected, and the simulation migration results can provide an effective reference for the treatment of metal ions in soil.

[0040] In this embodiment, the steps S1 to S5 are repeatedly performed 1 to 5 times; wherein, during the repeated execution, the sampling points are reselected; or, some or all of the sampling points selected later are located near the corresponding sampling points selected for the first time. In this embodiment, the above method can be used to obtain multiple simulated samples with different or similar soil components, increase the number of related metal ion migration simulations on the simulated samples, and improve the accuracy of the simulation test results.

[0041] for example Figure 5 As shown in the figure, vertical sampling is repeated once near sampling point 1#, numbered 1-1#. The remaining sampling points 2~18# are also repeated once in the same way at the corresponding nearby positions. After the final stacking and combination, a Figure 3 Similar simulation specimens.

[0042] In this embodiment, the image acquisition device used in step S1 is a camera or an aerial photography drone.

[0043] Specifically, when the image acquisition device used in step S1 is a camera, the specific process of determining the longitude and latitude coordinates corresponding to the sampling point according to the pixel coordinates of the sampling point in the two-dimensional plane image of the ground surface taken by the camera is as follows: Step SA11, establishing a camera overlooking coordinate system; Step SA12, calculating the distance coordinates (cx, cy) of the pixel coordinates (px, py) of the sampling points in the x-direction and the y-direction in the camera's top-view coordinate system one by one; Step SA13, calculating the coordinate position (ex,ey) of the pixel coordinate (px,py) in the ground coordinate system with the camera as the origin according to the distance coordinate (cx,cy); Step SA14, calculating the longitude and latitude coordinates (ex_long, ex_lat) corresponding to the pixel coordinates (px, py) according to the longitude and latitude coordinates (camera_long, camera_lat) of the camera itself and the coordinate position (ex, ey).

[0044] For further specific conversion process, please refer to the published Chinese invention, title: "Method, system and storage medium for calculating longitude and latitude of detected position in camera image", announcement number: CN110009571B, announcement date: 20230721.

[0045] When the image acquisition device used in step S1 is an aerial photography drone, the specific process of determining the longitude and latitude coordinates corresponding to the sampling point according to the pixel coordinates of the sampling point in the two-dimensional plane image of the ground surface taken by the aerial photography drone is as follows: Step SB11, the aerial photography drone acquires at least three consecutive aerial images; any one of the aerial images is used as the two-dimensional plane image of the ground surface for demarcating the sampling boundary line and the sampling point; Step SB12, using SIFT algorithm and the aerial image to construct a pixel coordinate and GPS coordinate conversion model; Step SB13, obtain the pixel coordinates (px, py) of the sampling points one by one, and input the pixel coordinates (px, py) into the pixel coordinate and GPS coordinate conversion model to calculate the real GPS coordinates, and output the longitude and latitude coordinates (ex_long, ex_lat) corresponding to the pixel coordinates (px, py).

[0046] For further specific conversion process, please refer to the published Chinese invention application, title: "Method, device, computer equipment and storage medium for calibrating longitude and latitude of aerial image pixel points", publication number: CN115457124A, publication date: 20221209.

[0047] In addition to the above-described coordinate processing method of determining the longitude and latitude coordinates corresponding to the sampling point according to the pixel coordinates of the sampling point in the two-dimensional surface plane image, other existing known coordinate processing methods can be used for coordinate processing in this embodiment.

[0048] In this embodiment, before vertical sampling is performed in step S2, the altitude value of each sampling point is first determined, and the altitude values ​​are sorted from high to low, and then the sampling point corresponding to the highest altitude value is selected as the reference sampling point for vertical sampling, and the remaining sampling points are vertically sampled based on the corresponding altitude values ​​and the reference sampling point as the reference, to ensure that the position points at the lowest end of the surface of all the sampling points are roughly coplanar when vertical sampling is performed. In this embodiment, the ups and downs of the surface within the sampling boundary line can be simulated through the above sampling method to fit the actual surface conditions as much as possible and improve the accuracy of the simulation.

[0049] When there are multiple sampling points corresponding to the highest altitude value, any one of them is used as the reference sampling point.

[0050] for example Figure 2 Among the sampling points 1#~18#, it is assumed that the altitude of sampling point 1# is the highest and is used as the benchmark sampling point. Sampling points 2#~18# are sampled vertically based on sampling point 1#. The effect is as follows: Figure 6 as shown in .

[0051] In this embodiment, the initial metal ion concentration detection of the primary soil sample in step S3 includes the following process: Step S31, firstly divide the primary soil sample collected at the reference sampling point into n soil sampling test areas along the height direction of the primary soil sample, each soil sampling test area having the same height, and then obtain a suitable amount of soil from each soil sampling test area to perform metal ion concentration detection; Step S32, for the primary soil samples collected at the remaining sampling points, refer to the same method as the reference sampling point, divide the soil sampling test areas with equal heights from bottom to top, and obtain a suitable amount of soil for metal ion concentration detection; if the top of the primary soil sample fails to form a complete soil sampling test area, no metal ion concentration detection is performed, or it is still recorded as the soil sampling test area and metal ion concentration detection is performed.

[0052] When the metal ion concentration of the secondary soil sample is detected in step S5, it is performed with reference to step S31 and step S32.

[0053] for example Figure 2 Among the 18 primary soil samples collected from sampling points 1# to 18#, the primary soil sample collected from sampling point 1# is divided into 8 soil sampling test areas according to the height. Figure 7 As shown in the figure, the primary soil samples collected from sampling points 2#~18# are executed in the same way as the primary soil sample collected from sampling point 1#. Take an appropriate amount of soil (for example, take 5~10g of soil each time) from any three points in each soil sampling test area for testing. When comparing subsequent data, the average test results of each soil sampling test area on the same primary soil sample can be used as a reference, or the test results of soil sampling test areas at the same height on different primary soil samples can be compared as the object, which is determined according to the test requirements.

[0054] In this embodiment, after the metal ion concentration detection is completed for the secondary soil sample in step S4, the secondary simulation sample is stacked and assembled again with reference to step S3, and then the metal ion concentration detection is performed again with reference to step S4, and finally the metal ion migration simulation test data is obtained with reference to step 5. In this embodiment, through repeated simulations, the migration of metal ions in the soil and the influencing factors can be fully analyzed from multiple angles.

Claims

1. A simulation test method for metal ion migration in soil, characterized in that: The following steps are involved: Step S1, obtaining a two-dimensional plane image of the surface of the area to be evaluated taken by an image acquisition device, and delineating a sampling boundary line and sampling points on the two-dimensional plane image of the surface; the sampling points are distributed on the sampling boundary line and in the area surrounded by the sampling boundary line; according to the pixel coordinates of the sampling points in the two-dimensional plane image of the surface, determining the longitude and latitude coordinates corresponding to the sampling points; Step S2, performing vertical sampling in the area to be evaluated according to the latitude and longitude coordinates of the sampling points determined in step S1, recording the relative position information of each sampling point, and performing initial metal ion concentration detection on the primary soil sample collected at each sampling point; Step S3, the primary soil samples collected from all the sampling points are arranged vertically. After determining the geometric center of the figure formed by the sampling boundary lines on the two-dimensional plane image of the ground surface, the primary soil sample collected from the sampling point closest to the geometric center is used as the vertical stacking center, and the primary soil samples collected from the remaining sampling points are moved closer to the vertical stacking center according to the relative position information of each sampling point recorded in step S2 and the distance from the vertical stacking center, and are stacked and combined to form a simulated sample with no gaps and a flush bottom surface, and the side walls of the simulated sample are wrapped with plastic film; wherein, if there are still gaps after the adjacent primary soil samples are brought close to each other and in contact, the same soil with known metal ion types and concentrations is used to fill them; Step S4, dripping a preset volume of clean water or metal ion solution at any position on the top of the simulated sample formed in step S3, and after reaching a preset simulation time, dividing the simulated sample according to the position when it was stacked and combined in step S3, and re-dividing it into secondary soil samples corresponding to the primary soil samples collected at each sampling point, and then performing metal ion concentration detection on the secondary soil samples; Step S5, comparing the changes in metal ion concentrations of the primary soil sample and the corresponding secondary soil sample collected at the same sampling point, to obtain metal ion migration simulation test data.

2. The method for simulating the migration of metal ions in soil according to claim 1, characterized in that: The steps S1 to S5 are repeatedly performed 1 to 5 times; wherein, during the repeated execution, the sampling points are reselected; or, part or all of the sampling points selected later are located near the corresponding sampling points selected for the first time.

3. The method for simulating the migration of metal ions in soil according to claim 1 or 2, characterized in that: The image acquisition device used in step S1 is a camera. The specific process of determining the longitude and latitude coordinates corresponding to the sampling point according to the pixel coordinates of the sampling point in the two-dimensional plane image of the ground surface taken by the camera is as follows: Step SA11, establishing a camera overlooking coordinate system; Step SA12, calculating the distance coordinates (cx, cy) of the pixel coordinates (px, py) of the sampling points in the x-direction and the y-direction in the camera's top-view coordinate system one by one; Step SA13, calculating the coordinate position (ex,ey) of the pixel coordinate (px,py) in the ground coordinate system with the camera as the origin according to the distance coordinate (cx,cy); Step SA14, calculating the longitude and latitude coordinates (ex_long, ex_lat) corresponding to the pixel coordinates (px, py) according to the longitude and latitude coordinates (camera_long, camera_lat) of the camera itself and the coordinate position (ex, ey).

4. The method for simulating the migration of metal ions in soil according to claim 1 or 2, characterized in that: The image acquisition device used in step S1 is an aerial photography drone. The specific process of determining the longitude and latitude coordinates corresponding to the sampling point according to the pixel coordinates of the sampling point in the two-dimensional plane image of the ground surface taken by the aerial photography drone is as follows: Step SB11, the aerial photography drone acquires at least three consecutive aerial images; any one of the aerial images is used as the two-dimensional plane image of the ground surface for demarcating the sampling boundary line and the sampling point; Step SB12, using SIFT algorithm and the aerial image to construct a pixel coordinate and GPS coordinate conversion model; Step SB13, obtain the pixel coordinates (px, py) of the sampling points one by one, and input the pixel coordinates (px, py) into the pixel coordinate and GPS coordinate conversion model to calculate the real GPS coordinates, and output the longitude and latitude coordinates (ex_long, ex_lat) corresponding to the pixel coordinates (px, py).

5. The method for simulating the migration of metal ions in soil according to claim 1, characterized in that: When vertical sampling is performed in step S2, a sampling tube with a polygonal or circular cross section is used.

6. The method for simulating the migration of metal ions in soil according to claim 1, 2 or 5, characterized in that: Before vertical sampling is performed in step S2, the altitude value of each sampling point is first determined, and the altitude values ​​are sorted from high to low, and then the sampling point corresponding to the highest altitude value is selected as the reference sampling point for vertical sampling, and the remaining sampling points are vertically sampled based on the corresponding altitude values ​​and the reference sampling point as a reference, to ensure that the position points deepest to the ground surface are roughly coplanar when all the sampling points are vertically sampled.

7. The method for simulating the migration of metal ions in soil according to claim 6, characterized in that: The initial metal ion concentration detection of the primary soil sample in step S3 includes the following process: Step S31, firstly divide the primary soil sample collected at the reference sampling point into n soil sampling test areas along the height direction of the primary soil sample, each soil sampling test area having the same height, and then obtain a suitable amount of soil from each soil sampling test area to perform metal ion concentration detection; Step S32, for the primary soil samples collected at the remaining sampling points, refer to the same method as the reference sampling point, divide the soil sampling test areas with equal heights from bottom to top, and obtain a suitable amount of soil for metal ion concentration detection; if the top of the primary soil sample fails to form a complete soil sampling test area, no metal ion concentration detection is performed, or it is still recorded as the soil sampling test area and metal ion concentration detection is performed.

8. The method for simulating the migration of metal ions in soil according to claim 7, characterized in that: When the metal ion concentration of the secondary soil sample is detected in step S5, it is performed with reference to step S31 and step S32.

9. The method for simulating the migration of metal ions in soil according to claim 1 or 2, characterized in that: The simulated sample prepared in step 3 is first placed in an environment with a temperature of 25±1° C. and a humidity of 40±1% RH for 1 to 10 days before subsequent testing.

10. The method for simulating the migration of metal ions in soil according to claim 1 or 2, characterized in that: After the metal ion concentration test is completed for the secondary soil sample in step S4, it is stacked and combined again with reference to step S3 to form a secondary simulation sample, and then the metal ion concentration test is performed again with reference to step S4, and finally the metal ion migration simulation test data is obtained with reference to step 5.

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