A device and method for simulating the vertical migration of pollutants in a multi-medium in an ice-encased environment

Abstract

The application relates to an ice environment pollutant multi-medium vertical migration simulation device and a use method, and belongs to the technical field of environment simulation and environment monitoring. The device comprises an outer protective shell of the simulation device, a multi-medium simulation experiment barrel in the outer protective shell of the simulation device, a light energy-electric energy dual energy power supply system connected with the multi-medium simulation experiment barrel through external lead wires, a low-temperature control system in the multi-medium simulation experiment barrel, and a multi-parameter water quality sensor. The low-temperature control system, the multi-parameter water quality sensor and the light energy-electric energy dual energy power supply system can avoid the icing interference of the simulation device at the lateral and bottom in the long-term low-temperature environment, so that the simulation device can only exchange with the simulation environment in the vertical direction, and consistent environment conditions with the natural icing and ice melting process are provided; in addition, the layered collection of water samples in the multi-medium migration process can be realized, and the device has the characteristics of strong environment simulation, high-frequency monitoring of water quality, dual energy power supply and the like.

Description

Technical Field

[0001] This invention belongs to the field of environmental simulation and environmental monitoring technology, and involves environmental simulation of water samples from rivers, lakes and reservoirs during the ice-covered period. In particular, it involves the whole-process simulation study of the vertical migration and release effects of pollutants in the ice-water-sediment multi-media during the ice-covered period. Background Technology

[0002] The ecological environment is the foundation of my country's high-quality development. my country has a vast territory with significantly varying environmental conditions, with cold regions accounting for over 40% of the country's land area. The unique ice-covered environment in winter directly alters the migration and transformation processes of pollutants. Studies show that rivers, lakes, and reservoirs in cold regions form ice sheets during the ice-covered period. Due to the "salt discharge effect" of the freezing process, pollutants accumulate in the surface water, increasing the concentration of pollution in the surface water. Subsequently, as temperatures rise, the high concentration of pollutants accumulated on the surface increases the risk of water pollution in the spring. Furthermore, large amounts of sediment, industrial and domestic wastewater, and waste from human activities enter natural water bodies, forming sediments. The adsorption and release of pollutants from these sediments also have a significant impact on water quality. Driven by both ice and sediment, the vertical migration process of water pollutants in winter undergoes significant changes. However, the harsh conditions of the ice-covered environment in winter, especially in the early stages of ice growth and the late stages of ice melting, greatly limit environmental monitoring under ice-covered conditions. The characteristics and impacts of vertical pollutant migration under multi-media conditions of ice, water, and sediment remain unclear, making winter water quality management a weak link in current environmental supervision. Designing physical simulation experiments to obtain the multi-media pollution migration process in a frozen environment is a good option. The challenge lies in ensuring that the device achieves a vertical unidirectional icing and melting process similar to natural winter conditions. Currently, common physical simulation devices mainly use insulation cotton and foam filling to keep the experimental device warm, and then conduct the simulation in a cryogenic control chamber. This method is difficult to effectively achieve unidirectional cooling. In the later stages of the experiment, ice forms on the bottom and sides of the simulation device, and the ice morphology includes different forms such as loose ice particles and compacted ice layers, thus affecting the simulation results. In addition, there are in-situ observation experiments, which monitor the ice formation and melting process by constructing an in-situ monitoring platform. This method approximates the natural state as closely as possible, but it is usually only possible to conduct near the shore and is difficult to adapt to the analysis of ice formation and melting processes in different regions. Achieving vertical, unidirectional icing and melting process simulation and eliminating lateral and bottom influences are crucial for the simulation.

[0003] In summary, to systematically study the vertical migration processes of pollutants between ice and water, water and sediment, and ice and water and sediment in winter environments, and to provide a basis for winter environmental management, it is necessary to develop a multi-media pollutant migration simulation device with vertical and unidirectional low-temperature control functions and wide applicability, specifically tailored to the unique winter frozen environment and the actual state of multi-media coexistence of ice, water, and sediment. Summary of the Invention

[0004] The technical problem this invention aims to solve is to provide a simulation device for the migration and release of pollutants in ice, water, and sediments in rivers, lakes, and reservoirs under frozen conditions. This device has good environmental adaptability and, in conjunction with a cryogenic control chamber or natural winter processes, can simulate the vertical and unidirectional freezing and melting processes of natural processes. It can simulate the vertical migration processes of pollutants in ice-water systems, water-sediment systems, and ice-water-sediment systems (long-term and short-term), and can monitor environmental parameters such as pH, dissolved oxygen, and temperature in real time during the simulation process, providing equipment support for pollutant management in winter environments.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A multi-media vertical migration simulation device for pollutants in a frozen environment includes an outer protective shell, a multi-media simulation experimental tank located inside the outer protective shell, a dual-energy power supply system (photovoltaic and electrical) connected to the multi-media simulation experimental tank via external wires, a low-temperature control system, and a multi-parameter water quality sensor located inside the multi-media simulation experimental tank. Details are as follows:

[0007] The multi-media simulation experimental tank consists of a cylindrical experimental tank body, water intake pipes, and control valves. The default design includes 10 layers, which can be adjusted according to specific experiments. Layered water intake pipes are arranged on the cylindrical experimental tank body; to reduce wall effects, one end of each pipe extends to the center of the tank body. The connection between the cylindrical experimental tank body and the water intake pipes is sealed with anti-freezing silicone sealant to ensure the airtightness of the cylindrical experimental tank body. Each layer of the water intake pipe is equipped with a control valve made of stainless steel. The stopcock is a six-part circular valve, facilitating control of the water flow rate during sampling and providing stable hydraulic conditions for the sampling process.

[0008] The cryogenic control system consists of temperature sensor A, a control panel, resistance wires, a convection fan, and a resistance wire carrier. Temperature sensor A is located on the outer wall of the cylindrical experimental tank, with one sensor installed at the surface, middle, and bottom layers. It is used to measure the temperature of the multi-media simulation experimental tank. The temperature information acquired by temperature sensor A is transmitted to the control panel via a circuit. The resistance wires are wound in a loop on the resistance wire carrier. When energized, they convert electrical energy into heat energy, providing the heat source for the temperature control of the entire device. Preliminary research shows that the water temperature gradually increases from the surface to the bottom layer in winter. The surface temperature is usually above 0°C, and the bottom layer temperature is below 4°C. The control panel compares the measured temperature with the set value. That is, if any layer temperature is below 0°C, the resistance wire heating mode is activated; if the bottom layer temperature is above 4°C or the surface temperature is above 1.5°C, the resistance wire heating mode is deactivated. These values ​​are default values ​​and can be adjusted according to different areas to simulate the lateral and bottom temperature scenarios under natural freezing conditions. This avoids interference from lateral and bottom icing under long-term low-temperature conditions, ensuring that the device can only exchange with the simulated environment vertically, providing environmental conditions consistent with the natural freezing and melting process. Four convection fans are installed diagonally on the top and bottom surfaces of the rectangular box. Viewed from above, the lines connecting the relative positions of the fans are perpendicular to each other, facilitating vertical air convection to ensure uniform distribution of hot air around the multi-media simulation chamber and prevent water from freezing from the sides and bottom during the simulation. Considering the gradual temperature increase from the surface to the bottom in a naturally frozen environment, the four fans are independently controlled via a control panel, allowing for individual control of their on / off status and speed. By default, the bottom fan is at a low speed, and the upper fan is at a high speed, ensuring that the bottom layer is hotter than the surface. The resistance wire carrier consists of four ceramic cylinders and a pair of ceramic rings vertically connected to prevent the carrier from conducting electricity when the resistance wire is energized.

[0009] The multi-parameter water quality sensor mainly consists of a temperature sensor (B), a pH sensor, a DO sensor, and a control panel. It uses a suspended method to monitor water quality at the center of the experimental tank. The monitoring position is adjusted according to water quality changes during ice growth and melting. Multiple layers can be deployed depending on the experimental purpose, with the default being surface, middle, and bottom layers. The water sample information acquired by the sensor is transmitted to the control panel via wiring, and the rate of water quality change is calculated. The control panel has a power switch and four operation buttons. These buttons allow for real-time display of water quality parameters and change rates in different areas of the water sample. A signal is emitted when the rate of water quality change exceeds a set value, scientifically increasing the monitoring frequency for more accurate understanding of multi-media pollution processes in winter frozen environments.

[0010] The solar-electric dual-energy power supply system comprises solar cell modules, terminals, a battery storage box, and three-prong power outlets. The solar cell modules consist of parallel-connected individual solar cell strings, an inverter, and a charge controller. Solar energy is converted into electrical energy and stored in the batteries. The battery storage box has two three-prong power outlets for alternating battery charging. A total of three batteries are installed, with two in use and one as backup, to prevent power shortages due to weather or unforeseen circumstances. Considering prolonged cloudy weather and other inclement conditions, the batteries can be charged indoors to maintain experimental operation. When the battery charge drops below 20%, the power module on the control panel will flash continuously, requiring timely charging to ensure the experiment continues.

[0011] The outer protective shell of the simulation device consists of a mesh dust filter, suspension rods, and aluminum alloy plates. A circular hole is cut into the center of the top surface to allow the experimental water sample to communicate with the external environment, facilitating sample collection. The mesh dust filter and suspension rods are installed at the opening. The mesh dust filter effectively filters dust and other impurities, reducing the likelihood of dust and solid impurities acting as condensation nuclei when the water freezes at low temperatures, thus avoiding interference with the experiment. The suspension rods are used to secure the multi-parameter sensors that extend into the cylindrical experimental tank. The bottom of the outer protective shell of the simulation device features a square, thickened platform to house the cylindrical experimental tank and reduce ground temperature transfer.

[0012] The control panel consists of a display screen, system buttons, and a power switch. The display screen has four areas: pH display area (upper left), DO display area (upper right), temperature (T) display area (lower left), and power display area (lower right). The red button is the power switch, and the green button is the simulation device operation switch. Left 1 button A is the function key, left 2 button B is the calibration key, right 1 button D is the toggle key, and right 2 button C is the adjustment key. Cycle temperature setting: After powering on, press and hold button A to enter the initial adjustment mode, and briefly press button D once to switch the temperature adjustment mode. The cursor in the temperature display area will start flashing. Press button C to set the temperature for the freezing and thawing periods. Temperature Module: Press and hold button A for 3 seconds to enter initial adjustment mode. Briefly press button D once to switch to temperature display mode; the cursor in the temperature display area will start flashing. Briefly press button B once to display the real-time temperature sensed by each sensor in the temperature display area (3 layers by default). pH Module: Press and hold button A for 3 seconds to enter initial adjustment mode. Briefly press button D twice to switch to pH display mode; the cursor in the pH display area will start flashing. Briefly press button B once to display the real-time pH value sensed by each sensor in the pH display area (3 layers by default). DO Module: Press and hold button A for 3 seconds to enter initial adjustment mode. Briefly press button D three times to switch to DO display mode; the cursor in the DO display area will start flashing. Briefly press button B once to display the real-time DO value sensed by each sensor in the DO display area (3 layers by default). Battery Module: Press and hold button A for 3 seconds to enter initial adjustment mode. Briefly press button D four times to switch to battery display mode; the cursor in the battery display area will start flashing. Briefly press button B once to display the current remaining battery level. When the battery level drops below 20%, the power display will flash continuously, indicating that the battery needs to be charged promptly.

[0013] A method for using a multi-media vertical migration simulation device for pollutants in a frozen environment includes the following steps:

[0014] Step 1: Transport the simulation device to an outdoor simulation site or cryogenic control room. Open the top mesh dust filter cover 5-1 and place the sediment into the bottom of the columnar experimental barrel 1-1. The sediment can be taken from any location on site and is not limited by near-shore conditions. Slowly pour simulated water (in-situ water sample, experimental water with different concentration gradients, etc.) along the inner wall of the columnar experimental barrel 1-1 to complete the multi-media system setup. Sediment is not required when simulating the ice-water process alone.

[0015] Step 2: Start the simulation device. Use the buttons on the control panel 2-2 to set the temperatures for the freezing and melting periods. Heating wire 2-3 will turn the heating mode on or off during the simulation period according to the set parameters. Convection fan 2-4 will adjust its speed according to the set parameters, enabling lateral and bottom heat convection in the multi-media simulation experimental tank 1, creating a distribution with a low surface temperature and a high bottom temperature, providing a stable low-temperature environment in winter. At this time, only the top of the device is exposed to the external environment, thus simulating the freezing and melting process under natural conditions to accurately analyze the vertical migration and release patterns of pollutants in the ice-water-sediment multi-media system.

[0016] Step 3: Stratified sample collection, combining routine sampling with variable-point sampling. Routine sampling typically involves a fixed sampling frequency, such as once daily. Variable-point sampling monitors dissolved oxygen, DO, and pH, with more frequent sampling when there are sudden changes in water quality. During sample collection, open control valves 1-3 to collect samples using sampling bottles. After collecting the samples, close control valves 1-3 and record the sampling time, ice thickness, and environmental information. To minimize sample collection interference, stratified sample collection should be performed from the surface to the bottom layer. Do not open two or more control valves 1-3 simultaneously to avoid disturbing the water body.

[0017] Step 4: When replenishing the experimental water sample, select the water intake pipe 1-2 that is closest to the upper part of the current water interface, open the control valve 1-3, push the prepared water sample into the water intake pipe 1-2 through the syringe to restore it to the initial water level, close the control valve 1-3, and end the water replenishment.

[0018] Step 5: Repeat steps 3 and 4 to simulate the multi-media vertical migration of pollutants during the entire ice formation and melting process (winter environment).

[0019] The beneficial effects of this invention are as follows:

[0020] This invention utilizes a cryogenic control system, a multi-parameter water quality sensor, and a dual-energy power supply system (solar and electrical) to avoid lateral and bottom icing interference from the simulation device under long-term low-temperature conditions. This ensures that the device can only exchange energy with the simulated environment vertically, providing environmental conditions consistent with natural freezing and melting processes. The beneficial effects of this invention are: effectively eliminating lateral and bottom icing interference from the simulation device under long-term low-temperature conditions; enabling stratified collection of water samples during multi-media migration; and featuring strong environmental simulation, high-frequency water quality monitoring, and dual-energy power supply. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of a multi-media vertical migration simulation device for pollutants in a frozen environment;

[0022] In the diagram: 1. Multi-media simulation experimental tank; 2. Low-temperature control system; 3. Multi-parameter water quality sensor; 4. Dual-energy power supply system (solar and electrical); 5. Outer protective shell of the simulation device; 6. External power cord.

[0023] Figure 2 This is a schematic diagram of a multi-media simulation experimental tank;

[0024] In the diagram: 1-1 cylindrical experimental tank; 1-2 water intake pipe; 1-3 control valve;

[0025] Figure 3 This is a schematic diagram of a low-temperature control system;

[0026] In the diagram: 2-1 Temperature sensor A; 2-2 Control panel; 2-3 Resistance wire; 2-4 Convection fan; 2-5 Resistance wire carrier;

[0027] Figure 4 (a) is a schematic diagram of the installation of a multi-parameter water quality sensor; Figure 4 (b) is a schematic diagram of a multi-parameter water quality sensor;

[0028] In the diagram: 3-1 Temperature sensor B; 3-2 pH sensor; 3-3 DO sensor; 2-2 Control panel;

[0029] Figure 5 This is a schematic diagram of a dual-energy power supply system combining solar and electrical power.

[0030] In the diagram: 4-1 Solar panel; 4-2 Terminal block; 4-3 Battery storage box; 4-4 Three-prong power socket;

[0031] Figure 6 (a) is a schematic diagram of the outer protective casing of the simulation device; Figure 6 (b) is a schematic diagram of the internal structure of the outer protective shell of the simulation device;

[0032] In the diagram: 5-1 Mesh dust filter cover; 5-2 Suspension rod; 5-3 Aluminum alloy sheet;

[0033] Figure 7 This is a diagram of the control panel. Detailed Implementation

[0034] The specific embodiments of the present invention are described in detail below with reference to the technical solution (and accompanying drawings).

[0035] A multi-media vertical migration simulation device for pollutants in a frozen environment is characterized in that the multi-media vertical migration simulation device includes an outer protective shell 5, a multi-media simulation experimental tank 1 located inside the outer protective shell 5, a light-electric dual-energy power supply system 4 connected to the multi-media simulation experimental tank 1 via an external wire, a low-temperature control system 2, and a multi-parameter water quality sensor 3 located inside the multi-media simulation experimental tank 1.

[0036] The multi-media simulation experimental tank 1 includes a cylindrical experimental tank body 1-1, 10 layers of water intake pipes 1-2 evenly distributed vertically, and control valves 1-3. One end of each water intake pipe 1-2 extends to the central area of ​​the cylindrical experimental tank body 1-1 to reduce wall effect; a control valve 1-3 is installed at the other end of each layer of water intake pipe 1-2 to control the flow rate of water during sampling, providing stable hydraulic conditions for the sampling process; the connection between the cylindrical experimental tank body 1-1 and the water intake pipes 1-2 is sealed with anti-freezing glass glue, and the control valves 1-3 are made of stainless steel with six equally divided circular stopcocks.

[0037] The low-temperature control system 2 includes a temperature sensor A2-1, a control panel 2-2, a resistance wire 2-3, a convection fan 2-4, and a resistance wire carrier 2-5. The multiple temperature sensors A2-1 are located on the outer wall of the cylindrical experimental barrel 1-1, with one temperature sensor A2-1 installed on each of the surface, middle, and bottom layers. The temperature information acquired by the temperature sensors A2-1 is transmitted to the control panel 2-2 via a line. The resistance wire carrier 2-5 is located on the outside of the cylindrical experimental barrel 1-1 and does not contact the barrel wall. It consists of two upper and lower ceramic rings and four vertically arranged ceramic cylinders positioned between the ceramic rings. The resistance wire 2-3 is wound in a ring shape. The resistance wire is wound around the carrier 2-5. Four convection fans 2-4 are installed diagonally on the top and bottom surfaces of the cuboid housing 5 of the simulation device. From a top-down view, the lines connecting the relative positions of the convection fans 2-4 are perpendicular to each other, facilitating vertical air convection to ensure uniform distribution of hot air around the multi-media simulation experimental tank 1 and preventing water from freezing from the sides and bottom during the simulation. Considering the gradual increase in temperature from the surface to the bottom in a naturally frozen environment, the four convection fans 2-4 are independently controlled by the control panel 2-2, allowing for individual control of their on / off status and speed. By default, the bottom fan is at a low speed, and the upper fan is at a high speed, ensuring that the bottom layer is hotter than the surface. The control panel 2-2 compares the measured temperature with the set value: when any layer temperature is below 0℃, the resistance wire heating mode is activated; when the bottom layer temperature is above 4℃ or the surface temperature is above 1.5℃, the resistance wire heating mode is deactivated. These values ​​are default values ​​and can be adjusted according to different areas to simulate the side and bottom temperature scenarios in a naturally frozen environment.

[0038] The control panel 2-2 includes a display screen, system buttons, and a power switch. The display screen has four areas: pH display area (upper left), DO display area (upper right), temperature (T) display area (lower left), and power display area (lower right). The red button is the power switch, and the green button is the simulation device operation switch. Left 1 button A is a function key, left 2 button B is a calibration key, right 1 button D is a toggle key, and right 2 button C is an adjustment key. For cycle temperature setting: After powering on, press and hold button A to enter the initial adjustment mode, then press button D once to switch the temperature adjustment mode. The cursor in the temperature display area will start flashing. Press button C to set the temperature for the freezing and melting periods. For the temperature module: Press and hold button A for 3 seconds to enter the initial adjustment mode, then press button D once to switch to the temperature display mode. The cursor in the temperature display area will start flashing. Press button B once to display the real-time temperature readings sensed by each sensor in the temperature display area. pH Module (default 3 layers): Press and hold button A for 3 seconds to enter the initial adjustment mode. Press button D twice to switch to pH display mode; the cursor in the pH display area will start flashing. Press button B once to display the real-time pH values ​​sensed by each sensor in the pH display area (default 3 layers). DO Module: Press and hold button A for 3 seconds to enter the initial adjustment mode. Press button D three times to switch to DO display mode; the cursor in the DO display area will start flashing. Press button B once to display the real-time DO values ​​sensed by each sensor in the DO display area (default 3 layers). Battery Module: Press and hold button A for 3 seconds to enter the initial adjustment mode. Press button D four times to switch to battery display mode; the cursor in the battery display area will start flashing. Press button B once to display the current remaining battery power. When the battery power is below 20%, the battery module on the display will flash continuously; timely charging is required to ensure the experiment can proceed.

[0039] The multi-parameter water quality sensor 3 is controlled by the control panel 2-2 and includes multiple sets of sensors, each consisting of a temperature sensor B3-1, a pH sensor 3-2, and a DO sensor 3-3. The three sets of sensors are suspended vertically at the center axis of the cylindrical experimental tank 1-1 to monitor the water quality at the center of the cylindrical experimental tank 1-1. The water sample information acquired by the multi-parameter water quality sensor 3 is transmitted to the control panel 2-2 via a line, and the water quality change rate is calculated. The control panel 2-2 is equipped with a power switch and four control buttons. By controlling the control buttons, the water quality parameters and change rates of different areas in the water sample can be displayed in real time. When the water quality change rate is higher than the set value, a signal is emitted to increase the monitoring frequency and accurately grasp the multi-media pollution process in the winter frozen environment.

[0040] The aforementioned solar-electric dual-energy power supply system 4 includes a solar cell module 4-1, a terminal block 4-2, a battery storage box 4-3, and a three-hole power socket 4-4. The solar cell module 4-1 consists of a series of individual solar cells connected in parallel, an inverter, and a charging controller, which converts solar energy into electrical energy and sends it to the battery for storage. The battery storage box 4-3 is equipped with a three-hole power socket 4-4, which can charge the battery in turn. A total of 3 batteries are provided, 2 for use and 1 for backup, to avoid power shortages caused by weather or emergencies. Considering severe weather, the batteries can be charged indoors to maintain the experiment. When the remaining battery power is below 20%, the power module on the control panel 2-2 will flash continuously, requiring timely charging to ensure the experiment can continue.

[0041] The outer protective shell 5 of the simulation device includes a mesh dust filter cover 5-1, a suspension rod 5-2, and an aluminum alloy plate 5-3. A circular hole is cut in the center of the upper surface to allow the experimental water sample to communicate with the external environment, facilitating the collection of the water sample. The mesh dust filter cover 5-1 and the suspension rod 5-2 are arranged at the opening. The suspension rod 5-2 is used to fix the multi-parameter sensor 3 that extends into the cylindrical experimental barrel 1-1. The bottom of the outer protective shell 5 of the simulation device is designed with a square thickened platform for placing the cylindrical experimental barrel 1-1 and reducing the transfer of ground temperature.

[0042] The steps for using a multi-media vertical migration simulation device for pollutants in a frozen environment are as follows:

[0043] Step 1: Transport the apparatus to an outdoor simulation site or cryogenic control room. Open the top mesh dust filter cover 5-1 and carefully place the sediment into the bottom of the cylindrical experimental tank 1-1. The sediment can be collected from any location on-site, without being restricted by near-shore conditions. Slowly pour simulated water (in-situ water sample, experimental water with different concentration gradients, etc.) along the inner wall of the cylindrical experimental tank 1-1 to complete the multi-media system setup. Sediment is not required when simulating the ice-water process alone.

[0044] Step 2: Start the simulation device. Use the buttons on the control panel 2-2 to set the temperatures for the freezing and melting periods. Heating wire 2-3 will turn the heating mode on or off during the simulation period according to the set parameters. Convection fan 2-4 will adjust its speed according to the set parameters, enabling lateral and bottom heat convection in the multi-media simulation experimental tank 1, creating a distribution with a low surface temperature and a high bottom temperature, providing a stable low-temperature environment in winter. At this time, only the top of the device is exposed to the external environment, thus simulating the freezing and melting process under natural conditions to accurately analyze the vertical migration and release patterns of pollutants in the ice-water-sediment multi-media system.

[0045] Step 3: Stratified sample collection, combining routine sampling with variable-point sampling. Routine sampling typically involves a fixed sampling frequency, such as once daily. Variable-point sampling monitors dissolved oxygen, DO, and pH, with more frequent sampling when there are sudden changes in water quality. During sample collection, open control valves 1-3 to collect samples using sampling bottles. After collecting the samples, close control valves 1-3 and record the sampling time, ice thickness, and environmental information. To minimize sample collection interference, stratified sample collection should be performed from the surface to the bottom layer. Do not open two or more control valves 1-3 simultaneously to avoid disturbing the water body.

[0046] Step 4: When replenishing the experimental water sample, select the water intake pipe 1-2 that is closest to the upper part of the current water interface, open the control valve 1-3, push the prepared water sample into the water intake pipe 1-2 through the syringe to restore it to the initial water level, close the control valve 1-3, and end the water replenishment.

[0047] Step 5: Repeat steps 3 and 4 to simulate the multi-media vertical migration of pollutants during the entire ice formation and melting process (winter environment).

[0048] The above-described embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A device for simulating the vertical migration of pollutants in multiple media under frozen conditions, characterized in that, The pollutant multi-media vertical migration simulation device includes an outer protective shell (5), a multi-media simulation test tank (1) located inside the outer protective shell (5), a light-electric dual-energy power supply system (4) connected to the multi-media simulation test tank (1) via an external wire, a low-temperature control system (2) located inside the multi-media simulation test tank (1), and a multi-parameter water quality sensor (3). The cryogenic control system (2) includes a temperature sensor A (2-1), a control panel (2-2), a resistance wire (2-3), a convection fan (2-4), and a resistance wire carrier (2-5). Multiple temperature sensors A (2-1) are located on the outer wall of the cylindrical experimental barrel (1-1) to measure the temperature of the multi-medium simulation experimental barrel (1). The temperature information obtained by the temperature sensors A (2-1) is transmitted to the control panel (2-2) via a line. The control panel (2-2) has a preset value designed according to the actual situation. The resistance wire carrier (2-5) is located on the outside of the cylindrical experimental barrel (1-1) and does not contact the cylindrical wall of the cylindrical experimental barrel (1-1). It consists of two upper and lower ceramic rings and four vertically arranged ceramic cylinders between the ceramic rings. The resistance wire (2-3) is wound in a ring around the resistance wire carrier (2-5). When energized, it converts electrical energy into heat energy, providing the heat source for temperature control of the entire device. The control panel (2-2) compares the measured temperature with the preset value and then selects to turn the resistance wire heating mode on or off to simulate a natural freezing environment. The side and bottom temperature scenarios are avoided to prevent the side and bottom icing interference of the simulation device under long-term low temperature environment, so that it can only exchange with the simulation environment in the vertical direction, and provide environmental conditions consistent with the natural freezing and melting process; Four convection fans (2-4) are installed at the opposite corners of the top and bottom surfaces of the cuboid box of the outer protective shell (5) of the simulation device. From the top view angle, the lines connecting the relative positions of the convection fans (2-4) are perpendicular to each other, which plays the role of air convection in the upper and lower parts, so as to ensure that the hot air around the multi-media simulation experimental barrel (1) is evenly distributed, and to avoid water freezing from the side and bottom during the simulation process. Considering the gradual increase of temperature from the surface to the bottom layer under natural freezing environment, the four convection fans (2-4) are independently controlled by the control panel (2-2), which can control the start and stop and the gear. The default is that the bottom fan is in the low gear and the upper fan is in the high gear, so that the bottom heat is higher than the surface. A temperature sensor A (2-1) is installed on the outer wall of the columnar experimental barrel (1-1) at the surface, middle and bottom layers respectively; in the low temperature control system (2), the control panel (2-2) compares the measured temperature with the set value: when the temperature of any layer is less than 0℃, the resistance wire heating mode is turned on, and when the bottom layer temperature is greater than 4℃ or the surface layer temperature is greater than 1.5℃, the resistance wire heating mode is turned off, so as to simulate the temperature scenario of the side and bottom under natural ice-free environment.

2. The multi-media vertical migration simulation device for pollutants in a frozen environment according to claim 1, characterized in that, The multi-media simulation experimental barrel (1) includes a cylindrical experimental barrel body (1-1), multiple layers of water intake pipes (1-2) distributed vertically at equal intervals, and control valves (1-3). The number of layers of water intake pipes (1-2) is adjusted according to the specific experiment. One end of the water intake pipe (1-2) extends to the central area of ​​the cylindrical experimental barrel body (1-1) to reduce the wall effect. A control valve (1-3) is installed at the other end of each layer of water intake pipe (1-2) to control the flow rate of water during water intake and provide stable hydraulic conditions for the sampling process.

3. The multi-media vertical migration simulation device for pollutants in a frozen environment according to claim 2, characterized in that, The water intake pipe (1-2) is preferably 10 layers; the connection between the columnar experimental barrel (1-1) and the water intake pipe (1-2) is sealed with anti-freezing glass glue to ensure the airtightness of the columnar experimental barrel (1-1); the control valve (1-3) is made of stainless steel and the stopcock is a six-part circle.

4. The multi-media vertical migration simulation device for pollutants in a frozen environment according to claim 3, characterized in that, The control panel (2-2) includes a display screen, system buttons, and power switch. The display screen has four areas: pH display area, DO display area, temperature T display area, and power display area, including a power switch and a simulation device operation switch.

5. The multi-media vertical migration simulation device for pollutants in a frozen environment according to claim 2, characterized in that, The multi-parameter water quality sensor (3) is controlled by the control panel (2-2) and includes multiple sets of sensors, each consisting of a temperature sensor B (3-1), a pH sensor (3-2), and a DO sensor (3-3). The multiple sets of sensors are suspended vertically along the central axis of the columnar experimental barrel (1-1) to monitor the water quality at the center of the columnar experimental barrel (1-1) and adjust the monitoring position according to the ice growth and melting process. The water sample information obtained by the multi-parameter water quality sensor (3) is transmitted to the control panel (2-2) through the line and the water quality change rate is calculated. The control panel (2-2) is equipped with a switch button and four control buttons. Through the control buttons, the water quality parameters and change rates of different areas in the water sample are displayed in real time. When the water quality change rate is higher than the set value, a signal is issued to increase the monitoring frequency and accurately grasp the multi-media pollution process in the winter ice-covered environment.

6. The multi-media vertical migration simulation device for pollutants in a frozen environment according to claim 2, characterized in that, The solar-electric dual-energy power supply system (4) includes solar cell modules (4-1), terminals (4-2), a storage box (4-3), and a three-hole power socket (4-4). The solar cell module (4-1) consists of a single solar cell string, an inverter, and a charging controller connected in parallel. It converts solar energy into electrical energy and sends it to the storage battery for storage. The storage box (4-3) is equipped with a three-hole power socket (4-4) to charge the storage battery in turn. A total of 3 storage batteries are set up, 2 for use and 1 for backup, to avoid power shortage caused by weather and emergencies. At the same time, considering the bad weather, the storage battery can be charged indoors to maintain the experiment. When the remaining battery power is less than 20%, the power module on the control panel (2-2) will flash continuously, and it needs to be charged in time to ensure the experiment can continue.

7. The multi-media vertical migration simulation device for pollutants in a frozen environment according to claim 2, characterized in that, The outer protective shell (5) of the simulation device includes a mesh dust filter cover (5-1), a suspension rod (5-2) and an aluminum alloy plate (5-3). A circular hole is cut in the center of the upper surface to allow the experimental water sample to communicate with the external environment, making it convenient to take the water sample. The mesh dust filter cover (5-1) and the suspension rod (5-2) are arranged at the opening. The suspension rod (5-2) is used to fix the multi-parameter water quality sensor (3) that extends into the columnar experimental barrel (1-1). The bottom of the outer protective shell (5) of the simulation device is designed with a square thickened platform for placing the columnar experimental barrel (1-1) and reducing the transfer of ground temperature.

8. A method of using the multi-media vertical migration simulation device for pollutants in an ice-bound environment as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Transport the simulation device to an outdoor simulation site or a cryogenic control room, open the top mesh dust filter cover (5-1), place the sediment into the bottom of the columnar experimental barrel (1-1), the sediment can be taken from any point on site; slowly pour simulated water along the inner wall of the columnar experimental barrel (1-1) to complete the construction of the multi-media system. When simulating the ice-water process alone, it is not necessary to add sediment. Step 2: Start the simulation device and use the buttons on the control panel (2-2) to set the temperature during the freezing and melting periods. The resistance wire (2-3) turns the heating mode on or off during the simulation period according to the set parameters. The convection fan (2-4) adjusts its speed according to the set parameters to allow convection between the side and bottom heat sources in the multi-media simulation experimental tank 1, forming a distribution with a low surface layer and a high bottom layer, providing a stable low-temperature environment in winter. At this time, only the top of the device is exposed to the external environment, thereby simulating the freezing and melting process under natural conditions, so as to accurately analyze the vertical migration and release patterns of pollutants in the ice-water-sediment multi-media. Step 3: Stratified sample collection, combining routine sampling with variable-point sampling. Routine sampling typically involves a fixed sampling frequency, while variable-point sampling monitors dissolved oxygen, DO, and pH. Intensified sampling is used when there are sudden changes in water quality. During sample collection, open control valves (1-3) and use sampling bottles to collect samples. After collecting the samples, close control valves (1-3) and record the sampling time, ice thickness, and environmental information. Stratified sample collection should be carried out in the order from the surface to the bottom layer. Do not open two or more control valves (1-3) simultaneously to avoid disturbing the water body. Step 4: When replenishing the experimental water sample, select the water intake pipe (1-2) that is closest to the upper part of the current water interface, open the control valve (1-3), push the prepared water sample into the water intake pipe (1-2) through the syringe to restore it to the initial water level, close the control valve (1-3) to end the water replenishment; Step 5: Repeat steps 3 and 4 to simulate the multi-media vertical migration of pollutants throughout the entire ice formation and decay process.

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