A method and system for simulating heavy metal cross-media migration

Abstract

This invention belongs to the field of soil environmental big data, specifically involving a simulation method and system for heavy metal cross-media migration. The method includes: 1) constructing a simulation device for heavy metal cross-media migration, mainly comprising an atmospheric module, a soil module, a groundwater module, and an automatic control module; 2) designing the device's operating parameters based on environmental scenarios for each module; 3) fixing the model simulation parameters using the Hydrus-1D model based on measured values ​​of heavy metal content, media weight or volume, and soil properties; and 4) evaluating the impact of cross-media migration by setting an evaluation period, defining target time points, and evaluating the heavy metal pollution level in soil and water media at specific time points. This method provides theoretical and methodological support for the prevention and control of heavy metal cross-media pollution in environmental systems.

Description

Technical Field

[0001] This invention belongs to the field of soil environmental big data, specifically relating to a simulation method and system for the cross-media migration of heavy metals. Background Technology

[0002] During my country's rapid economic development, environmental pollution problems such as air, soil, and water pollution have emerged, gradually forming regional, cumulative, and multi-media pollution characteristics and an overall pattern. Although my country has made great achievements in environmental governance theory and technology after more than 10 years of concentrated efforts, it still cannot meet the national concept of "comprehensive environmental protection" and the needs of systematic governance.

[0003] Regional cross-media complex pollution control and remediation place greater emphasis on a holistic, systemic, and spatiotemporally multi-scale perspective, comprehensively analyzing pollution occurrence mechanisms at the regional level to achieve full-process pollution prevention and control. From a scientific understanding perspective, the environment is a complex system composed of multiple media, including air, water, and soil, forming a continuous multi-media system. After pollutants enter the environment, they not only migrate and attenuate within a single medium but also undergo transfer processes between media.

[0004] Furthermore, existing research primarily focuses on simulating pollutant migration and transformation within a single medium or on the interfacial physicochemical reaction processes between two media. Research on cross-media migration of pollutants at a regional scale remains insufficient. In particular, considering the differences in the secondary distribution and accumulation rates of heavy metals in water, air, and soil at the regional scale, how these ultimately affect heavy metal pollution levels in different media remains a challenge, requiring adequate technical methods.

[0005] In conclusion, considering the impact of heavy metal cross-media migration on the long-term accumulation of soil and water, establishing a simulation method and system for heavy metal cross-media migration can provide scientific and technological support for regional-scale comprehensive environmental management and precise pollution control. Summary of the Invention

[0006] In view of the above-mentioned defects and deficiencies of the prior art, the purpose of this invention is to provide a simulation method and system for the cross-medium migration of heavy metals.

[0007] A method for simulating the migration of heavy metals across media includes the following steps:

[0008] A simulation device for the cross-media migration of heavy metals was constructed to simulate the cross-media migration environment of soil and spray solution mixture;

[0009] Soil spraying and sampling control steps: Based on the environmental scenario and combined with the parameters of the simulation device, fill the simulation chamber with soil, prepare the spraying solution, and control the spraying process and water sample collection process;

[0010] Model Solving and Prediction Steps: The environmental parameters of cross-medium migration are measured, and combined with the parameters of the simulation device, the Hydrus-1D model is used to fit and optimize the model parameters for solving the heavy metal cross-medium migration model, obtaining an ideal model. This ideal model is used to predict the heavy metal content in the medium in future years based on the known heavy metal content in the medium in the current year. The model parameters include the optimized adsorption partition coefficient Kd and the proportion of equilibrium adsorption sites. f ;

[0011] Evaluation and prediction data steps: Set the evaluation duration, define the target time nodes, and evaluate the heavy metal pollution level in soil and water media at the predicted future year time nodes.

[0012] The simulation device for heavy metal cross-media migration includes:

[0013] An atmospheric module, used to simulate the deposition of cadmium in the atmospheric medium, includes a reservoir, a pressure pump, and a sprayer, which are connected in sequence by pipelines. The reservoir is used to store spray liquid to simulate the deposition of heavy metals in the atmosphere, the sprayer is used to spray and atomize the soil placed below it, and the pressure pump is used to adjust the pressure of the spray liquid.

[0014] The soil module, used to simulate the vertical migration of heavy metal elements in soil media, includes a simulation chamber, a pore water collector, and a peristaltic pump. The simulation chamber is used to fill soil, and its bottom has an opening for draining excess spray liquid. The pore water collector is inserted into the soil to extract pore water, and then connected to the peristaltic pump through a pipeline. The peristaltic pump collects the pore water to obtain a water sample.

[0015] The groundwater module, used to simulate the enrichment of heavy metal elements in groundwater, includes a liquid collector, a water sampler, and a capillary tube. The upper opening of the liquid collector is used to collect the spray liquid that seeps into the soil of the simulation chamber. The water sampler is inserted into the liquid collector to extract the groundwater inside, and then connected to the peristaltic pump through a pipeline. The peristaltic pump collects the groundwater to obtain a water sample. The capillary tube is placed vertically, with its bottom end extending into the groundwater in the liquid collector and its top end penetrating the bottom of the simulation chamber and extending into the soil to simulate the disturbance of groundwater on the soil.

[0016] The automatic control module includes a power supply, a liquid level sensor, a solenoid valve, and a PLC. The PLC is connected to the liquid level sensor, a pressure pump, a peristaltic pump, and the solenoid valves installed on each pipeline. It is used to control the opening degree of each solenoid valve, control the operation of the pressure pump and the peristaltic pump, simulate the spray control of atmospheric deposition, soil pore water extraction, and groundwater sampling, and realize the environmental simulation of heavy metal cross-media migration.

[0017] The environmental scenarios described are natural environments formed by different soil types and terrains;

[0018] The parameters of the simulation device include atmospheric parameters, soil parameters, groundwater parameters, and automatic control parameters:

[0019] Atmospheric parameters include the heavy metal content (C) of the spray liquid. A and total amount of spray liquid V L ;

[0020] Soil parameters include soil type and soil filling height H. S The soil types mentioned include, but are not limited to, single varieties or combinations of black soil and red soil.

[0021] Groundwater parameters include the influence of capillary groundwater on soil moisture content at height H. W ;

[0022] The automatic control parameters include the single spray volume V. SL Spraying time T A Spraying interval T int Pore ​​water sampling period T S Groundwater sampling cycle T W .

[0023] The process of filling the simulation chamber with soil involves filling the simulation chamber with soil according to the soil type and soil layer thickness of the environmental scenario.

[0024] The spray solution is configured with a heavy metal content C based on the annual deposition of heavy metals and annual rainfall in the environmental scenario. A and total amount of spray liquid V L ;

[0025] The controlled spraying process is as follows: to avoid water accumulation on the soil surface from the spray liquid, the single spraying volume V is controlled according to... SL Spraying time T A Spraying interval time T int Controlling the opening degree of each solenoid valve and controlling the operation of the pressure pump to achieve spraying;

[0026] The controlled water sample collection process: based on the spray interval T int Set the pore water sampling period T S Based on the groundwater conditions in the environmental scenario, the influence height H of groundwater on soil moisture content is designed using capillary action. W According to the spray interval T int Design groundwater sampling cycle T W .

[0027] The cross-media migration environment parameters include:

[0028] The content of heavy metals in the medium, including the soil heavy metal content C S Groundwater heavy metal content C W ;

[0029] Medium weight or volume, including soil weight (W) S Groundwater volume V W ;

[0030] Soil properties, including the percentage of particle size distribution, i.e., sand F1, silt F2, clay F3, and soil bulk density SBD.

[0031] The process of using the Hydrus-1D model to fit and optimize the model parameters of the heavy metal cross-medium migration model to obtain an ideal model includes:

[0032] The Hydrus-1D model is set to input the parameters of the simulation device described above and the measured cross-media migration environmental parameters, and outputs the soil heavy metal content C for a future specified year. S Groundwater heavy metal content C W ;

[0033] Using the Hydrus-1D model, input the above settings and measured parameters, and optimize the solution for the model parameters: adsorption partition coefficient Kd and equilibrium adsorption site ratio. f ;

[0034] When the slope of the linear fit between the measured value and the predicted value output by the model k ∈[0.75, 1.25] and R 2 When the value is ≥ 0.8, the model performance is deemed reliable, and the optimized model parameters and ideal model are obtained.

[0035] It adopts the van Genuchten model structure from the Hydrus-1D model.

[0036] The evaluation and prediction of heavy metal pollution levels in soil and water media at future time points are as follows:

[0037] Setting the simulation duration means treating a single run of the simulation device as an annual result, setting the future evaluation duration, and defining time nodes in years.

[0038] The optimized model was used to simulate the unpredicted heavy metal content in soil and groundwater for a specified year.

[0039] The heavy metal pollution levels in soil and water media in a specified year were evaluated by referring to the soil environmental quality standards and groundwater quality standards.

[0040] A simulation system for cross-media migration of heavy metals includes: a simulation device for cross-media migration of heavy metals, a cloud server, and a host computer;

[0041] The heavy metal cross-media migration simulation device is used to adjust atmospheric parameters, groundwater parameters, and automatic control parameters according to the parameters and instructions input by the host computer, to simulate the cross-media migration environment of soil and spraying, and to collect water samples.

[0042] The cloud server is equipped with a database and a processor. The database stores programs, and the processor loads programs according to the parameters and instructions input by the host computer: executes soil spraying and controlled sampling steps to control the simulation device to adjust parameters and collect water samples; executes model solving and prediction steps to obtain model parameters and ideal models; executes evaluation and prediction data steps to obtain the results and evaluation results of heavy metal content in soil and groundwater in a future specified year; and interactively uploads data to the host computer.

[0043] The host computer is equipped with a front-end human-computer interaction interface and a control backend. The front-end interface is used to collect parameters and instructions input by the user and send them to the backend. The control backend calls the cloud server algorithm program to obtain the prediction results and evaluation results for a specified future year and displays them intuitively and visually through the front-end interface.

[0044] The parameters and instructions input by the user through the front-end interface include, but are not limited to, simulation device control parameters, acquisition instructions, algorithm formulas and algorithm parameters of the Hydrus-1D model, measured cross-media migration environmental parameters and evaluation thresholds; the simulation device control parameters include atmospheric parameters, groundwater parameters, and automatic control parameters.

[0045] The present invention has the following advantages and beneficial effects:

[0046] This invention addresses the "black box" of heavy metal migration processes in continuous environmental media of air, soil, and water. It focuses on the insufficient amount of time-series paired data in multiple media, making it difficult for traditional statistical methods to be applied to cross-media analysis at time scales. This invention proposes a simulation method for heavy metal cross-media migration, which can provide theoretical and methodological support for the prevention and control of heavy metal cross-media pollution in environmental systems. Attached Figure Description

[0047] Figure 1 This is a flowchart of the technology of the present invention.

[0048] Figure 2 This is a schematic diagram of the simulation device of the present invention.

[0049] Figure 3 This is a schematic diagram of the simulation system for the cross-medium migration of heavy metals according to the present invention.

[0050] Among them, 1 is the liquid storage tank, 2 is the pressure pump, 3 is the sprayer, 4 is the simulation chamber, 5 is the pore water collector, 6 is the peristaltic pump, 7 is the liquid collector, 8 is the water sample collector, 9 is the capillary tube, 10 is the industrial control box, 11 is the power supply, 12 is the liquid level sensor, 13 is the solenoid valve, and 14 is the PLC control system. Detailed Implementation

[0051] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0053] 1. A simulation method for the cross-media migration of heavy metals, comprising the following steps:

[0054] (1) Construct a simulation device for the cross-media migration of heavy metals, which mainly includes an atmospheric module, a soil module, a groundwater module and an automatic control module;

[0055] (2) The design of the device operating parameters is based on the environmental scenario, and the design of the operating parameters of each module of the device is based on the environmental scenario;

[0056] (3) Fixed model simulation parameters are determined by using the Hydrus-1D model based on the measured values ​​of heavy metal content, medium weight or volume, and soil properties in the medium.

[0057] (4) To evaluate the impact of cross-media migration, the evaluation period is set, the target time node is defined, and the heavy metal pollution level in soil and water media at a specific time node is evaluated.

[0058] Step (1) is as follows:

[0059] Constructing a simulation device for the cross-media migration of heavy metals, such as... Figure 2 As shown, the main modules are as follows:

[0060] 1) Atmospheric module refers to the simulation of cadmium deposition in atmospheric media, including liquid storage tank, pressure pump, and sprayer;

[0061] 2) Soil module refers to the simulation of the vertical migration of cadmium in soil media, including simulation chamber, pore water collector, and peristaltic pump;

[0062] 3) Groundwater module refers to the simulation of cadmium enrichment in groundwater media, including a liquid collector, a water sampler, and a capillary tube;

[0063] 4) The automatic control module refers to the industrial control box, power supply, liquid level sensor, solenoid valve, and PLC, which are used for spray control to simulate atmospheric deposition, soil pore water extraction, and groundwater sampling.

[0064] Step (2) is as follows:

[0065] 1) Atmospheric module parameter design is based on the annual deposition and annual rainfall of heavy metals in the environmental scenario, and the design of the heavy metal content (C) of the spray liquid is determined. A (mg / L) and total amount of spray solution (V L To avoid water accumulation on the soil surface from the spray solution, the designed single spray volume (V) is [not specified]. SL L), spraying time (T) A ,s), spray interval time (T) int (day);

[0066] 2) Soil module parameter design involves filling the simulation chamber with soil of the corresponding type based on the soil type of the environmental scenario; and designing the soil filling height (H) based on the soil layer thickness of the scenario. S (cm); based on the spray interval (T) int (day), design pore water sampling cycle (T) S (day);

[0067] 3) Groundwater module parameter design involves using capillary tubes to design the height (H) of the groundwater's influence on soil moisture content, based on the groundwater conditions in the environmental scenario. W (cm); based on the spray interval (T) int (day), design groundwater sampling cycle (T) W (day);

[0068] 4) The automatic control module design uses solenoid valves, sensors, and a PLC control system to control the single spray volume (V). SL L), spraying time (T) A ,s), spray interval time (T) int (day), pore water sampling period (T) S (day), groundwater sampling cycle (T) W (day), and ensure stable operation of the device.

[0069] Step (3) is as follows:

[0070] 1) Determine the heavy metal content in the medium, including the heavy metal content in the soil (C S (mg / kg), groundwater heavy metal content (C W (mg / L)

[0071] 2) Measure the weight or volume of the medium, including soil weight (W).S (kg), groundwater volume (V) W (L)

[0072] 3) Determine soil properties, including particle size distribution, i.e., sand (F1, %), silt (F2, %), clay (F3, %), and soil bulk density (SBD, g / cm³). 3 );

[0073] 4) Using the Hydrus-1D model, input the relevant parameters set and measured above to optimize the adsorption partition coefficient (Kd) and the proportion of equilibrium adsorption sites (Kd). f Specifically, it adopts the van Genuchten model structure from the Hydrus-1D model.

[0074] 5) When the slope of the linear fit between the measured value and the simulated value ( k )∈[0.75, 1.25] and R 2 When the value is ≥ 0.8, the model performance is reliable, and the model parameters are determined.

[0075] Step (4) is as follows:

[0076] 1) Setting the simulation duration involves treating a single operation of the device as a year and setting the duration for future evaluations. i = 1, 2, 3, 4, 5 …… (times). i It also represents the corresponding year;

[0077] 2) Define time nodes in years;

[0078] 3) Simulate soil heavy metal content (C) for a specified year Sj (mg / kg) and groundwater heavy metal content (C Wj (mg / L) j It represents the specified year;

[0079] 4) Evaluate the heavy metal pollution level in soil and water media for a specified year, referring to the Soil Environmental Quality Standard (GB15618) and the Groundwater Quality Standard (GB14848). The specific formula is as follows:

[0080] P Sj = C Sj / S S (1)

[0081] P Wj = C Wj / S W (2)

[0082] Among them, P Si It represents the first j Annual soil heavy metal contamination levels (dimensionless); SS This refers to the heavy metal limits in the soil environmental quality standards, expressed in mg / kg; P Wi It represents the first j Annual groundwater heavy metal contamination levels (dimensionless); S S It is the heavy metal limit in the groundwater quality standard, in mg / L.

[0083] Example 1

[0084] The subject selected in this embodiment is a metal-emitting industrial zone in Liaoning Province. The soil is brown soil, and the main heavy metal is cadmium (Cd), which mainly comes from industrial atmospheric emissions.

[0085] This embodiment presents a simulation method for the cross-medium migration of heavy metals, with specific implementation steps (see [link to implementation details]). Figure 1 ):

[0086] Step 1: Construct a simulation device for cadmium cross-media migration, such as... Figure 2 As shown, the details are as follows:

[0087] (1) Atmospheric module refers to the simulation of cadmium deposition in atmospheric medium, including liquid storage tank, pressure pump and sprayer;

[0088] (2) Soil module refers to the simulation of the vertical migration of cadmium in soil media, including simulation chamber, pore water collector, and peristaltic pump;

[0089] (3) Groundwater module refers to the simulation of cadmium enrichment in groundwater medium, including liquid collector, water sampler and capillary tube;

[0090] (4) The automatic control module refers to the industrial control box, power supply, liquid level sensor, solenoid valve, and PLC control system, which are used to simulate atmospheric deposition spray control, soil pore water extraction, and groundwater sampling. The PLC control system is used to interact with the cloud server, converting the received parameters and instructions into solenoid valve opening signals, peristaltic pump switching signals, and working signals for specific regulation. Table 1 shows the main module dimensions and parameters of the simulation device in Example 1. The peristaltic pump is controlled in a time sequence to extract and collect pore water and groundwater separately.

[0091] Table 1

[0092]

[0093] Step 2: Design the operating parameters of the device. Table 2 shows the parameters of the atmospheric module in Example 1, as follows:

[0094] (1) Atmospheric module parameter design is based on the annual cadmium deposition and annual rainfall in the environmental scenario, and the cadmium content (C) of the spray solution is designed. A (mg / L) and total amount of spray solution (V LTo avoid water accumulation on the soil surface from the spray solution, the designed single spray volume (V) is [not specified]. SL L), spraying time (T) A ,s), spray interval time (T) int (day);

[0095] Table 2

[0096]

[0097] (2) Soil module parameter design. Table 3 is the soil module parameter table for Example 1. Based on the soil type of the environmental scenario, the corresponding type of soil is filled in the simulation chamber; based on the soil layer thickness of the scenario, the soil filling height (H) is designed. S (cm); based on the spray interval (T) int (day), design pore water sampling cycle (T) S (day);

[0098] Table 3

[0099]

[0100] (3) Groundwater module parameter design. Table 4 is the groundwater module parameter table for Example 1. It is designed based on the groundwater conditions in the environmental scenario and using capillary tubes to determine the height (H) of the impact of groundwater on soil moisture content. W (cm); based on the spray interval (T) int (day), design groundwater sampling cycle (T) W (day);

[0101] Table 4

[0102]

[0103] (4) Automatic control module design. Table 5 shows the cadmium cross-medium simulation measurement indicators in Example 1. The single spray volume (V) is controlled by a solenoid valve, sensor, and PLC control system. SL L), spraying time (T) A ,s), spray interval time (T) int (day), pore water sampling period (T) S (day), groundwater sampling cycle (T) W (day), and ensure stable operation of the device.

[0104] Step 3: Fix the model simulation parameters, as follows:

[0105] (1) Determine the cadmium content in the medium, including the cadmium content in the soil (C S (mg / kg), cadmium content in groundwater (C W (mg / L)

[0106] (2) Determine the weight or volume of the medium, including soil weight (W). S (kg), groundwater volume (V) W (L)

[0107] (3) Determine soil properties, including particle size distribution, i.e., sand (F1, %), silt (F2, %), clay (F3, %), and soil bulk density (SBD, g / cm³). 3 );

[0108] Table 5

[0109]

[0110] (4) Using the Hydrus-1D model, input the relevant parameters set and measured above to optimize the adsorption partition coefficient (Kd) and the proportion of equilibrium adsorption sites (Kd). f );

[0111] (5) The slope of the linear fit between the measured value and the simulated value in this embodiment ( k R = 0.9373 2 =0.9492, which satisfies the linear fitting slope ( k )∈[0.75, 1.25] and R 2 The requirement of ≥ 0.8 indicates that the model performance is reliable. The above parameters are the model parameters for cadmium cross-medium simulation in this embodiment.

[0112] Step 4: Evaluate the impact of cross-media migration, as detailed below:

[0113] (1) In this embodiment, the effect of cadmium in atmospheric deposition is a slow process. Therefore, this embodiment aims to predict the cadmium accumulation in soil and groundwater over 10 years. Therefore, the simulation period is set to 10 years.

[0114] Since a single operation of the device is calculated as an annual result, the future evaluation period is set accordingly. i = 10 (times) i It also represents the corresponding year;

[0115] (2) This embodiment only considers a 10-year time node. Therefore, 10 years is defined as the time node simulated in this embodiment, with years as the unit.

[0116] (3) Based on steps one, two, and three, the soil cadmium content (C) was simulated over 10 years. S10 (mg / kg) and cadmium content in groundwater (C W10 Table 6 shows the cadmium content in soil and groundwater during a simulated 10-year period in Example 1 (mg / L).

[0117] Table 6

[0118]

[0119] (4) Evaluate the cadmium pollution level in soil and water media for a specified year, referring to the Soil Environmental Quality Standard (GB15618) and the Groundwater Quality Standard (GB14848). The specific formula is as follows:

[0120] P Sj = C Sj / S S (1)

[0121] P Wj = C Wj / S W (2)

[0122] Among them, P Si It represents the first j Annual soil cadmium exceedance level (dimensionless); S S This refers to the cadmium limit in the soil environmental quality standards, expressed in mg / kg; P Wi It represents the first j Annual groundwater cadmium exceedance level (dimensionless); S S This refers to the cadmium limit in the groundwater quality standard, expressed in mg / L. Table 7 shows the cadmium pollution levels in soil and groundwater over a simulated 10-year period in Example 1.

[0123] Table 7

[0124]

[0125] According to the evaluation results, at the current pollution intensity, cadmium in soil and groundwater will meet the corresponding environmental quality standards in 10 years. However, due to the accumulation of pollution, it is still necessary to pay attention to the accumulation of cadmium in the media and the changes in pollution levels over a longer time scale.

[0126] like Figure 3As shown, the present invention also provides a simulation system for heavy metal cross-media migration, comprising: a simulation device for heavy metal cross-media migration, a cloud server, and a host computer; the simulation device for heavy metal cross-media migration is used to adjust atmospheric parameters, groundwater parameters, and automatic control parameters according to parameters and instructions input by the host computer, to simulate the cross-media migration environment of soil and spraying, and to collect water samples; the cloud server is equipped with a database and a processor, the database stores programs, and the processor loads programs according to the parameters and instructions input by the host computer: executing soil spraying and controlled sampling steps to control the simulation device to adjust parameters and collect water samples; executing model solving and prediction steps to obtain model parameters and ideal models; executing evaluation and prediction data steps to obtain the results and evaluation results of heavy metal content in soil and groundwater in a future specified year; and interactively uploading data to the host computer; the host computer is equipped with a front-end human-computer interaction interface and a control backend; the front-end interface is used to collect parameters and instructions input by the user and send them to the backend, and the control backend calls the cloud server algorithm program to obtain the prediction results and evaluation results for the future specified year, and displays them intuitively and visually through the front-end interface. The parameters and instructions input by the user through the front-end interface include, but are not limited to: simulation device control parameters, acquisition instructions, algorithm formulas and algorithm parameters of the Hydrus-1D model, measured cross-media migration environmental parameters and evaluation thresholds; the simulation device control parameters include atmospheric parameters, groundwater parameters, and automatic control parameters.

[0127] The system described can be compiled using languages ​​such as C# and can run on Windows systems. It can be used to simulate the cross-media migration of heavy metals, providing theoretical and methodological support for the prevention and control of cross-media pollution of heavy metals in environmental systems.

[0128] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention and should not be construed as limiting the specific implementation of the invention to these embodiments. Several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for simulating the migration of heavy metals across media, characterized in that, Includes the following steps: A simulation device for the cross-media migration of heavy metals was constructed to simulate the cross-media migration environment of soil and spray solution mixture; Soil spraying and sampling control steps: Based on the environmental scenario and combined with the parameters of the simulation device, fill the simulation chamber with soil, prepare the spraying solution, and control the spraying process and water sample collection process; Model Solving and Prediction Steps: The environmental parameters of cross-medium migration are measured, and combined with the parameters of the simulation device, the Hydrus-1D model is used to fit and optimize the model parameters for solving the heavy metal cross-medium migration model, obtaining an ideal model. This ideal model is used to predict the heavy metal content in the medium in future years based on the known heavy metal content in the medium in the current year. The model parameters include the optimized adsorption partition coefficient Kd and the proportion of equilibrium adsorption sites. f ; Evaluation and prediction data steps: Set the evaluation duration, define the target time nodes, and evaluate the heavy metal pollution level in soil and water media at the predicted future year time nodes.

2. The simulation method for heavy metal cross-media migration according to claim 1, characterized in that, The simulation device for heavy metal cross-media migration includes: An atmospheric module, used to simulate the deposition of cadmium in the atmospheric medium, includes a reservoir, a pressure pump, and a sprayer, which are connected in sequence by pipelines. The reservoir is used to store spray liquid to simulate the deposition of heavy metals in the atmosphere, the sprayer is used to spray and atomize the soil placed below it, and the pressure pump is used to adjust the pressure of the spray liquid. The soil module, used to simulate the vertical migration of heavy metal elements in soil media, includes a simulation chamber, a pore water collector, and a peristaltic pump. The simulation chamber is used to fill soil, and its bottom has an opening for draining excess spray liquid. The pore water collector is inserted into the soil to extract pore water, and then connected to the peristaltic pump through a pipeline. The peristaltic pump collects the pore water to obtain a water sample. The groundwater module, used to simulate the enrichment of heavy metal elements in groundwater, includes a liquid collector, a water sampler, and a capillary tube. The upper opening of the liquid collector is used to collect the spray liquid that seeps into the soil of the simulation chamber. The water sampler is inserted into the liquid collector to extract the groundwater inside, and then connected to the peristaltic pump through a pipeline. The peristaltic pump collects the groundwater to obtain a water sample. The capillary tube is placed vertically, with its bottom end extending into the groundwater in the liquid collector and its top end penetrating the bottom of the simulation chamber and extending into the soil to simulate the disturbance of groundwater on the soil. The automatic control module includes a power supply, a liquid level sensor, a solenoid valve, and a PLC. The PLC is connected to the liquid level sensor, a pressure pump, a peristaltic pump, and the solenoid valves installed on each pipeline. It is used to control the opening degree of each solenoid valve, control the operation of the pressure pump and the peristaltic pump, simulate the spray control of atmospheric deposition, soil pore water extraction, and groundwater sampling, and realize the environmental simulation of heavy metal cross-media migration.

3. The simulation method for heavy metal cross-media migration according to claim 1, characterized in that, The environmental scenarios described are natural environments formed by different soil types and terrains; The parameters of the simulation device include atmospheric parameters, soil parameters, groundwater parameters, and automatic control parameters: Atmospheric parameters include the heavy metal content (C) of the spray liquid. A and total amount of spray liquid V L ; Soil parameters include soil type and soil filling height H. S The soil types mentioned include, but are not limited to, single varieties or combinations of black soil and red soil. Groundwater parameters include the influence of capillary groundwater on soil moisture content at height H. W ; The automatic control parameters include the single spray volume V. SL Spraying time T A Spraying interval time T int Pore ​​water sampling period T S Groundwater sampling cycle T W .

4. The simulation method for heavy metal cross-media migration according to claim 1, characterized in that, The process of filling the simulation chamber with soil involves filling the simulation chamber with soil according to the soil type and soil layer thickness of the environmental scenario. The spray solution is configured with a heavy metal content C based on the annual deposition of heavy metals and annual rainfall in the environmental scenario. A and total amount of spray liquid V L ; The controlled spraying process is as follows: to avoid water accumulation on the soil surface from the spray liquid, the single spraying volume V is controlled according to... SL Spraying time T A Spraying interval time T int Controlling the opening degree of each solenoid valve and controlling the operation of the pressure pump to achieve spraying; The controlled water sample collection process: based on the spray interval T int Set the pore water sampling period T S Based on the groundwater conditions in the environmental scenario, the influence height H of groundwater on soil moisture content is designed using capillary action. W According to the spray interval T int Design groundwater sampling cycle T W .

5. The simulation method for heavy metal cross-media migration according to claim 1, characterized in that, The cross-media migration environment parameters include: The content of heavy metals in the medium, including the soil heavy metal content C S Groundwater heavy metal content C W ; Medium weight or volume, including soil weight (W) S Groundwater volume V W ; Soil properties, including the percentage of particle size distribution, i.e., sand F1, silt F2, clay F3, and soil bulk density SBD.

6. The simulation method for heavy metal cross-media migration according to claim 1, characterized in that, The process of using the Hydrus-1D model to fit and optimize the model parameters of the heavy metal cross-medium migration model to obtain an ideal model includes: The Hydrus-1D model is set to input the parameters of the simulation device described above and the measured cross-media migration environmental parameters, and outputs the soil heavy metal content C for a future specified year. S Groundwater heavy metal content C W ; Using the Hydrus-1D model, input the above settings and measured parameters, and optimize the solution for the model parameters: adsorption partition coefficient Kd and equilibrium adsorption site ratio. f ; When the slope of the linear fit between the measured value and the predicted value output by the model k ∈[0.75, 1.25] and R 2 When the value is ≥ 0.8, the model performance is deemed reliable, and the optimized model parameters and ideal model are obtained.

7. The method for simulating the cross-medium migration of heavy metals according to claim 6, characterized in that, It adopts the van Genuchten model structure from the Hydrus-1D model.

8. The simulation method for heavy metal cross-media migration according to claim 1, characterized in that, The evaluation and prediction of heavy metal pollution levels in soil and water media at future time points are as follows: Setting the simulation duration means treating a single run of the simulation device as an annual result, setting the future evaluation duration, and defining time nodes in years. The optimized model was used to simulate the unpredicted heavy metal content in soil and groundwater for a specified year. The heavy metal pollution levels in soil and water media in a specified year were evaluated by referring to the soil environmental quality standards and groundwater quality standards.

9. A simulation system for the cross-medium migration of heavy metals, characterized in that, include: Simulation devices for cross-media migration of heavy metals, cloud servers, and host computers; The heavy metal cross-media migration simulation device is used to adjust atmospheric parameters, groundwater parameters, and automatic control parameters according to the parameters and instructions input by the host computer, to simulate the cross-media migration environment of soil and spraying, and to collect water samples. The cloud server is equipped with a database and a processor. The database stores programs, and the processor loads programs according to the parameters and instructions input by the host computer: executes soil spraying and controlled sampling steps to control the simulation device to adjust parameters and collect water samples; executes model solving and prediction steps to obtain model parameters and ideal models; executes evaluation and prediction data steps to obtain the results and evaluation results of heavy metal content in soil and groundwater in a future specified year; and interactively uploads data to the host computer. The host computer is equipped with a front-end human-computer interaction interface and a control backend. The front-end interface is used to collect parameters and instructions input by the user and send them to the backend. The control backend calls the cloud server algorithm program to obtain the prediction results and evaluation results for a specified future year and displays them intuitively and visually through the front-end interface.

10. A simulation system for heavy metal cross-media migration according to claim 9, characterized in that, The parameters and instructions input by the user through the front-end interface include, but are not limited to, simulation device control parameters, acquisition instructions, algorithm formulas and algorithm parameters of the Hydrus-1D model, measured cross-media migration environmental parameters and evaluation thresholds; the simulation device control parameters include atmospheric parameters, groundwater parameters, and automatic control parameters.

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