A method for simulating the migration of metal ions in soil

Abstract

The present invention aims to provide a method for simulating the migration of metal ions in soil, which relates to the technical field of detecting the heavy metal content in soil. The method for simulating the migration of metal ions in soil includes: obtaining a two-dimensional planar image of the surface of the area to be evaluated captured by an image acquisition device, demarcating a sampling boundary line and sampling points, and determining the longitude and latitude coordinates; vertically sampling, recording the relative position information of the sampling points, and detecting the initial metal ion concentration of the primary soil sample; stacking and combining to form a simulated sample; dropping a preset volume of clear water or metal ion solution at any position on the top of the simulated sample to simulate the migration of metal ions, cutting, and detecting the initial metal ion concentration of the secondary soil sample; and comparing data. The present invention has the characteristics of low implementation difficulty, relatively low cost, and the sampling period can be freely selected, and the simulated migration result can provide an effective reference for the treatment of metal ions in soil.

Description

Technical Field

[0001] The present invention relates to the technical field of detecting heavy metal content in soil, and particularly to a method for simulating and testing the migration of metal ions in soil. Background Art

[0002] With the continuous acceleration of the industrialization process and the continuous growth of the population, heavy metal pollution such as lead, copper, and zinc has become a global problem. The increasing human activities of mining, smelting, processing, and commercial manufacturing of heavy metals, and sudden water quality heavy metal pollution accidents caused by accidental leakage, illegal discharge, etc. occur from time to time. Heavy metals have the characteristics of high toxicity, being not easily metabolized in the environment, being easily bioaccumulated, and having a biological magnification effect. They will not only pollute the water environment but also seriously threaten the survival of humans and aquatic organisms. Therefore, it is self-evident the importance of clarifying the migration and transformation process of heavy metal ions in soil for the treatment of polluted soil.

[0003] At present, studying the migration and transformation process of heavy metals in soil through field tests not only has great operation difficulty, high cost consumption, but also has an overly long test period, and simply cannot meet the urgency of treating polluted soil at the present stage. Summary of the Invention

[0004] The present invention aims to provide a method for simulating and testing the migration of metal ions in soil, which has the characteristics of low implementation difficulty, relatively low cost, and a freely selectable sample period, and the simulated migration results can provide an effective reference for the treatment of metal ions in soil.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A method for simulating and testing the migration of metal ions in soil, comprising the following steps:

[0007] Step S1, obtaining a two-dimensional planar image of the surface of the area to be evaluated taken by an image acquisition device, and demarcating a sampling boundary line and sampling points on the two-dimensional planar image of the surface; the sampling points are distributed on the sampling boundary line and within the area surrounded by the sampling boundary line; according to the pixel coordinates of the sampling points in the two-dimensional planar image of the surface, determining the longitude and latitude coordinates corresponding to the sampling points;

[0008] Step S2, performing vertical sampling in the area to be evaluated according to the longitude and latitude coordinates of the sampling points determined in Step S1, simultaneously recording the relative position information of each sampling point, and detecting the initial metal ion concentration of the primary soil sample collected from each sampling point;

[0009] Step S3: All the primary soil samples collected at the sampling points are vertically arranged. After determining the geometric center of the figure formed by the sampling boundary lines on the surface two-dimensional plane image, the primary soil sample collected at the sampling point closest to the geometric center is used as the vertical stacking center, and the primary soil samples collected at the remaining sampling points approach 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 gapless and flat-bottomed simulated sample. The side wall of the simulated sample is wrapped with a plastic film. Wherein, if there are still gaps after the adjacent primary soil samples approach and contact each other, the same soil with known metal ion types and concentrations is used for filling;

[0010] Step S4: At any position on the top of the simulated sample formed in Step S3, a preset volume of clear water or metal ion solution is dropped. After reaching the preset simulation duration, the simulated sample is cut according to the position during stacking and combination in Step S3, and is re-divided into secondary soil samples corresponding to the primary soil samples collected at each sampling point respectively, and then the metal ion concentration of the secondary soil samples is detected;

[0011] Step S5: Compare the changes in the metal ion concentrations of the primary soil samples collected at the same sampling point and the corresponding secondary soil samples, and the metal ion migration simulation test data can be obtained.

[0012] Further, Steps S1 to S5 are repeatedly executed 1 to 5 times. Wherein, when repeating the execution, the sampling points are re-selected; or, some or all of the sampling points selected in the subsequent times are located near the corresponding sampling points selected for the first time.

[0013] Further, the image acquisition device used in Step S1 is a camera. According to the pixel coordinates of the sampling points in the surface two-dimensional plane image captured by the camera, the specific process of determining the longitude and latitude coordinates corresponding to the sampling points is as follows:

[0014] Step SA11: Establish a camera top-down coordinate system;

[0015] Step SA12: Calculate the distance coordinates (cx, cy) in the x-direction and y-direction of the pixel coordinates (px, py) of the sampling points in the camera top-down coordinate system one by one;

[0016] Step SA13: Calculate the coordinate position (ex, ey) of the pixel coordinates (px, py) in the ground coordinate system with the camera as the origin according to the distance coordinates (cx, cy);

[0017] Step SA14: Calculate the longitude and latitude coordinates (ex_long, ex_lat) corresponding to the pixel coordinates (px, py) based on the longitude and latitude coordinates (camera_long, camera_lat) of the camera itself and the coordinate position (ex, ey).

[0018] Further, the image acquisition device used in step S1 is an aerial photography drone. The specific process for 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 image captured by the aerial photography drone is as follows:

[0019] Step SB11: Obtain at least three consecutive aerial images by the aerial photography drone; any one of the aerial images is used as the two-dimensional surface image for delimiting the sampling boundary line and the sampling point.

[0020] Step SB12: Construct a conversion model between pixel coordinates and GPS coordinates using the SIFT algorithm and the aerial images.

[0021] Step SB13: Sequentially obtain the pixel coordinates (px, py) of the sampling point, and input the pixel coordinates (px, py) into the conversion model between pixel coordinates and GPS coordinates to calculate the true GPS coordinates, and output the longitude and latitude coordinates (ex_long, ex_lat) corresponding to the pixel coordinates (px, py).

[0022] Further, when performing vertical sampling in step S2, a sampling tube with a polygonal or circular cross-section is used for operation.

[0023] Further, before performing vertical sampling in step S2, first determine the altitude value of each sampling point, sort the altitude values from high to low, and then select the sampling point corresponding to the highest altitude value as the reference sampling point for vertical sampling. The remaining sampling points are vertically sampled based on the corresponding altitude values with the reference sampling point as the reference, ensuring that the position points at the deepest part of the surface when all sampling points are vertically sampled are approximately coplanar.

[0024] Further, when performing the initial metal ion concentration detection on the primary soil sample in step S3, the following process is included:

[0025] Step S31: First, divide the primary soil sample collected along the height direction of the primary soil sample at the reference sampling point into n soil sampling and testing areas with the same height, and then obtain an appropriate amount of soil from each soil sampling and testing area for metal ion concentration detection.

[0026] Step S32: For the primary soil samples collected from the remaining sampling points, divide the soil sampling and testing areas with equal height from bottom to top in the same way as for the reference sampling point, and obtain an appropriate amount of soil for metal ion concentration detection; if the top of the primary soil sample fails to form a complete soil sampling and testing area, then metal ion concentration detection is not performed, or it is still recorded as the soil sampling and testing area for metal ion concentration detection.

[0027] Further, when performing metal ion concentration detection on the secondary soil sample in step S5, it is carried out with reference to step S31 and step S32.

[0028] Further, the simulated specimens prepared in step S3 are first placed in an environment with a temperature of 25 ± 1 °C and a humidity of 40 ± 1% RH for 1 - 10 days, and then subsequent tests are carried out.

[0029] Further, after the metal ion concentration detection of the secondary soil sample in step S4 is completed, it is stacked and combined again with reference to step S3 to form a secondary simulated specimen, then the metal ion concentration detection is carried out again with reference to step S4, and finally the metal ion migration simulation test data is obtained with reference to step S5.

[0030] The beneficial effects of the present invention are:

[0031] The present invention provides a method for simulating the migration of metal ions in soil. By a specific sampling method, a simulated specimen relatively close to the topography and landform of the area to be evaluated is formed, then the migration of metal ions is simulated on the simulated specimen, and finally, the metal ion migration simulation test data can be obtained by comparing the changes in metal ion concentration before and after the simulation, which can be used for the soil situation in the area to be evaluated. This simulation test method has a low implementation difficulty, relatively low cost, a freely selectable test period, and the simulation migration results can provide an effective reference for the treatment of metal ions in soil. Description of the Drawings

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0033] Figure 1 It is a two-dimensional planar image of the surface of a certain area to be evaluated.

[0034] Figure 2 It is a two-dimensional planar image of the surface after the sampling boundary line and sampling points are delimited.

[0035] Figure 3 It is a top view of a simulated specimen formed by stacking and combining soil samples once.

[0036] Figure 4 It is a schematic diagram of the effect of a three-dimensional space effect model.

[0037] Figure 5 It is a schematic diagram of the repeated sampling positions.

[0038] Figure 6 It is a schematic diagram of the vertical sampling effect.

[0039] Figure 7 It is a schematic diagram of the division of the soil sampling test area. Specific implementation manners

[0040] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0041] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present invention.

[0042] The embodiments of the invention will be described in detail below with reference to the drawings.

[0043] A method for simulating and testing the migration of metal ions in soil includes the following steps:

[0044] Step S1, obtaining a two-dimensional planar image of the surface of the area to be evaluated captured by an image acquisition device, and delineating a sampling boundary line and sampling points on the two-dimensional planar 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 planar image of the surface, determining the longitude and latitude coordinates corresponding to the sampling points.

[0045] Among them, the sampling boundary line can be set randomly or can be set according to factors such as test requirements and surface topography. For example Figure 1 shows the two-dimensional planar image of the surface of a certain area to be evaluated. After delineating the sampling boundary line and sampling points on the two-dimensional planar image of the surface as shown in 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#.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] The simulated sample prepared in step S3 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.

[0050] 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 .

[0051] Step S4: At an arbitrary position on the top of the simulated specimen formed in the said Step S3, drip a preset volume (such as 1 L) of clear water or metal ion solution (such as 3 drops / min). After reaching the preset simulation duration (such as 48 h), cut the simulated specimen according to the positions during the stacking combination in the said Step S3, and re-segment it into secondary soil samples respectively corresponding to each primary soil sample collected at each sampling point. Then, detect the metal ion concentration of the secondary soil samples.

[0052] The migration of metal ions in soil mostly occurs along with the migration of moisture. In this embodiment, when using clear water for testing, the migration of the original metal ions in the soil can be simulated, and the influence degree of the original metal ions affected by the moisture migration can be reflected; when 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 clear water or metal ion solution can be selected according to requirements, and no specific limitation is made in this embodiment. For example Figure 3 When cutting the simulated specimen shown in Figure 3 , it is fully separated into 18 secondary soil samples according to the stacking combination position in Step S3.

[0053] Step S5: Compare the metal ion concentration changes of the primary soil samples collected at the same sampling point and the corresponding secondary soil samples, and then the metal ion migration simulation test data can be obtained.

[0054] For example, taking the pixel coordinates of the sampling point as the X-axis and Y-axis coordinates, and the metal ion concentration as the Z-axis coordinate, a three-dimensional coordinate diagram of the spatial distribution can be drawn. After smoothing processing, it forms a similar Figure 4 Schematic diagram of the three-dimensional space effect model shown in Figure 4 . By comparing the schematic diagrams of the three-dimensional space effect models before and after the two metal ion concentration detections, the change regions, migration directions, etc. of the corresponding metal ions can be observed, which can provide an effective reference for the treatment of metal ions in the soil.

[0055] In the method for simulating the migration of metal ions in soil in this embodiment, through a specific sampling method, a simulated specimen relatively close to the topography and landform of the area to be evaluated is formed. Then, the metal ion migration is simulated on this simulated specimen. Finally, by comparing the metal ion concentration changes before and after the simulation, the metal ion migration simulation test data can be obtained, which can be used for the soil conditions of the area to be evaluated. This simulation test method has a low implementation difficulty, relatively low cost, a freely selectable test period, and the simulation migration results can provide an effective reference for the treatment of metal ions in the soil.

[0056] In this embodiment, steps S1 to S5 are repeatedly executed 1 to 5 times; when repeating the execution, the sampling points are reselected; alternatively, some or all of the sampling points selected in subsequent times are located near the corresponding sampling points selected for the first time. By adopting the above method in this embodiment, multiple simulated specimens with different or similar soil components can be obtained, increasing the number of times of simulating the migration of relevant metal ions on the simulated specimens and improving the accuracy of the simulation test results.

[0057] For example Figure 5 As shown in, vertical sampling is repeated 1 time near the 1# sampling point, numbered 1-1#. The remaining 2-18# sampling points are also vertically sampled 1 time at the corresponding nearby positions in the same way. After final stacking and combination, a simulated specimen similar to that in Figure 3 can be obtained.

[0058] In this embodiment, the image acquisition device used in step S1 is a camera or an aerial drone.

[0059] 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 captured by the camera is as follows:

[0060] Step SA11, establish a camera top-down coordinate system;

[0061] Step SA12, calculate the distance coordinates (cx, cy) in the x direction and y direction of the pixel coordinates (px, py) of the sampling point in the camera top-down coordinate system one by one;

[0062] Step SA13, calculate the coordinate position (ex, ey) of the pixel coordinates (px, py) in the ground coordinate system with the camera as the origin according to the distance coordinates (cx, cy);

[0063] Step SA14, calculate 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).

[0064] For the further specific conversion process, reference can be made to the publicly disclosed Chinese invention, title: "Method, System and Storage Medium for Calculating Longitude and Latitude of Detection Position in Camera Image", publication number: CN110009571B, publication date: 20230721.

[0065] When the image acquisition device used in the step S1 is an aerial 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 surface image taken by the aerial drone is as follows:

[0066] Step SB11, obtain at least three consecutive aerial images by the aerial drone; any one of the aerial images is used as the two-dimensional surface image for delimiting the sampling boundary line and the sampling point;

[0067] Step SB12, construct a conversion model between pixel coordinates and GPS coordinates by using the SIFT algorithm and the aerial images;

[0068] Step SB13, obtain the pixel coordinates (px, py) of the sampling point one by one, and input the pixel coordinates (px, py) into the conversion model between pixel coordinates and GPS coordinates to calculate the real GPS coordinates, and output the longitude and latitude coordinates (ex_long, ex_lat) corresponding to the pixel coordinates (px, py).

[0069] Furthermore, for the specific conversion process, reference can be made to the published Chinese invention application, title: "Method, Device, Computer Equipment and Storage Medium for Calibrating Longitude and Latitude of Pixel Points in Aerial Images", publication number: CN115457124A, publication date: 20221209.

[0070] Except for 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 image, the remaining existing known coordinate processing methods can all be used for the coordinate processing in this embodiment.

[0071] In this embodiment, before vertical sampling in the step S2, first determine the altitude value of each sampling point, sort the altitude values from high to low, and then select the sampling point corresponding to the highest altitude value as the reference sampling point for vertical sampling. The remaining sampling points are vertically sampled based on the corresponding altitude values with the reference sampling point as the reference, ensuring that the position points at the lowest end of the surface when all the sampling points are vertically sampled are approximately coplanar. In this embodiment, through the above sampling method, the undulation of the surface within the sampling boundary line can be simulated to as closely fit the actual surface situation as possible, improving the accuracy of the simulation.

[0072] Wherein, when there are multiple sampling points corresponding to the highest altitude value, any one of them can be used as the reference sampling point.

[0073] For example Figure 2Among the sampling points 1# to 18# in [reference], assuming that the elevation value of the 1# sampling point is the highest and is used as the reference sampling point, the sampling points 2# to 18# are vertically sampled with the 1# sampling point as the reference. The effect is as Figure 6 shown in

[0074] In this embodiment, when detecting the initial metal ion concentration of the primary soil sample in step S3, the following process is included:

[0075] Step S31: First, divide the primary soil sample along the height direction of the primary soil sample collected at the reference sampling point into n soil sampling and testing areas, each soil sampling and testing area having the same height. Then, obtain an appropriate amount of soil from each soil sampling and testing area for metal ion concentration detection;

[0076] Step S32: For the primary soil samples collected at the remaining sampling points, refer to the same method as for the reference sampling point, divide the soil sampling and testing areas of equal height from bottom to top, and obtain an appropriate amount of soil for metal ion concentration detection; if the uppermost part of the primary soil sample fails to form a complete soil sampling and testing area, then no metal ion concentration detection is performed, or it is still recorded as the soil sampling and testing area for metal ion concentration detection.

[0077] When detecting the metal ion concentration of the secondary soil sample in step S5, refer to step S31 and step S32 for execution.

[0078] For example Figure 2 Among the 18 primary soil samples collected at the sampling points 1# to 18# in [reference], the primary soil sample collected at the 1# sampling point is divided into 8 soil sampling and testing areas according to the height as shown in Figure 7 shown in. For the primary soil samples collected at the sampling points 2# to 18# in [reference], refer to the method of the primary soil sample collected at the 1# sampling point for execution. Take an appropriate amount of soil from any three points in each soil sampling and testing area (for example, take 5 - 10 g of soil each time) for testing. When comparing the subsequent data, the average value of the test results of each soil sampling and testing area on the same primary soil sample can be taken as a control, or the test results of the soil sampling and testing areas at the same height on different primary soil samples can be compared as an object, which is specifically determined according to the test requirements.

[0079] In this embodiment, after the metal ion concentration of the secondary soil sample is detected in step S4, it is stacked and combined again with reference to step S3 to form a secondary simulated sample, then the metal ion concentration is detected again with reference to step S4, and finally the metal ion migration simulation test data is obtained with reference to step S5. In this embodiment, through repeated simulations, the migration situation and influencing factors of metal ions in the soil can be fully analyzed from multiple angles.

Claims

1. A method for simulating the migration of metal ions in soil, characterized in that, Including the following steps: Step S1: Obtain the two-dimensional surface image of the area to be evaluated captured by the image acquisition device, and demarcate a sampling boundary line and sampling points on the two-dimensional surface image; the sampling points are distributed on the sampling boundary line and within the area enclosed by the sampling boundary line; according to the pixel coordinates of the sampling points in the two-dimensional surface image, determine the corresponding longitude and latitude coordinates of the sampling points; Step S2: Conduct vertical sampling in the area to be evaluated according to the longitude and latitude coordinates of the sampling points determined in Step S1, record the relative position information of each sampling point at the same time, and conduct an initial metal ion concentration detection on the primary soil sample collected at each sampling point; Step S3: All the primary soil samples collected at the sampling points are in a vertical arrangement state. After determining the geometric center of the figure formed by the sampling boundary line on the two-dimensional surface image, take the primary soil sample collected at the sampling point closest to the geometric center as the vertical stacking center, and the primary soil samples collected at the remaining sampling points approach 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 stack and combine them to form a simulation sample without gaps and with a flat bottom, and wrap the side wall of the simulation sample with a plastic film; wherein, if there are still gaps after the adjacent primary soil samples come into contact and approach each other, use the same soil with known metal ion types and concentrations to fill the gaps; Step S4: Drop a preset volume of clear water or metal ion solution at any position on the top of the simulation sample formed in Step S3. After reaching the preset simulation duration, cut the simulation sample according to the position during stacking and combination in Step S3, and re-segment it into secondary soil samples corresponding to the primary soil samples collected at each sampling point respectively, and then conduct a metal ion concentration detection on the secondary soil samples; Step S5: Compare the changes in the metal ion concentrations of the primary soil sample and the corresponding secondary soil sample collected at the same sampling point, and thus obtain the metal ion migration simulation test data; Among them, before conducting vertical sampling in Step S2, first determine the elevation value of each sampling point, sort the elevation values from high to low, and then select the sampling point corresponding to the highest elevation value as the reference sampling point for vertical sampling. The remaining sampling points are vertically sampled with the reference sampling point as the reference according to the corresponding elevation values, ensuring that the position points at the lowest end deep into the surface are approximately coplanar when all the sampling points are vertically sampled.

2. The method for simulating the migration of metal ions in soil according to claim 1, wherein Steps S1 to S5 are repeatedly executed 1 to 5 times; wherein, when repeatedly executing, the sampling points are reselected; or, some or all of the sampling points selected in subsequent times 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 for determining the corresponding longitude and latitude coordinates of the sampling points according to the pixel coordinates of the sampling points in the two-dimensional surface image captured by the camera is as follows: Step SA11, establish a camera top-down coordinate system; Step SA12, calculate the distance coordinates (cx, cy) in the x and y directions of the pixel coordinates (px, py) of the sampling points in the camera top-down coordinate system one by one; Step SA13, calculate the coordinate position (ex, ey) of the pixel coordinates (px, py) in the ground coordinate system with the camera as the origin according to the distance coordinates (cx, cy); Step SA14, calculate 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 the step S1 is an aerial drone. The specific process of determining the longitude and latitude coordinates corresponding to the sampling points according to the pixel coordinates of the sampling points in the surface two-dimensional plane image captured by the aerial drone is as follows: Step SB11, obtain at least three consecutive aerial images by the aerial drone; any one of the aerial images is used as the surface two-dimensional plane image for delimiting the sampling boundary line and the sampling points; Step SB12, construct a pixel coordinate and GPS coordinate conversion model using the SIFT algorithm and the aerial images; 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, wherein When performing vertical sampling in the step S2, a sampling tube with a polygonal or circular cross-section is used for operation.

6. The method for simulating the migration of metal ions in soil according to claim 1, wherein When detecting the initial metal ion concentration of the primary soil sample in the step S2, the following process is included: Step S21, first divide the primary soil sample collected along the height direction of the primary soil sample at the reference sampling point into n soil sampling and testing areas, each soil sampling and testing area has the same height, and then obtain an appropriate amount of soil from each soil sampling and testing area for metal ion concentration detection; Step S22, for the primary soil samples collected at the other sampling points, refer to the same method for the reference sampling point, divide the soil sampling and testing areas with the same height from bottom to top, and obtain an appropriate amount of soil and then perform metal ion concentration detection; if the top of the primary soil sample fails to form a complete soil sampling and testing area, then no metal ion concentration detection is performed, or it is still recorded as the soil sampling and testing area and metal ion concentration detection is performed.

7. The method for simulating the migration of metal ions in soil according to claim 6, wherein, When detecting the metal ion concentration of the secondary soil sample in the step S4, refer to the step S21 and the step S22 for execution.

8. The method for simulating the migration of metal ions in soil according to claim 1 or 2, characterized in that, The simulated specimen prepared in the step S3 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, and then subsequent tests are carried out.

9. 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 of the secondary soil sample in step S4 is detected, a secondary simulated sample is formed by stacking and combining again with reference to step S3, then the metal ion concentration is detected again with reference to step S4, and finally the metal ion migration simulation test data is obtained with reference to step S5.

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