Soil pollutant migration and transformation simulation microcosm system and device thereof

Abstract

The invention relates to the technical field of pollutant environment process simulation and analysis, in particular to a soil pollutant migration and transformation simulation microcosm system and a device thereof, and the system and the device comprise a microcosm system used for simulating a soil environment of a polluted site; the function module units comprise a periodic precipitation unit, a temperature control unit, a space-time sequence sample preparation unit and a continuous undisturbed sampling unit; the experimental device of the microcosm system supports a multi-field coupled soil pollutant migration and transformation simulation test; according to the invention, by simulating the multi-medium cross-interface complex environment behavior of pollutants in polluted site soil and analyzing the coupling effect of a gravity field, a seepage field, a chemical field and a biological field, the problem that a traditional test device is difficult to restore the multi-field synergistic effect in a real soil environment is solved; and an analogue simulation analysis platform is provided for pollutant migration and transformation research.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of pollutant environmental process simulation and analysis, and particularly relates to a soil pollutant migration and transformation simulation microcosm system and a device thereof. BACKGROUND

[0002] Real-world oriented environmental process simulation and analysis can provide insights for the explanation of environmental problems and accumulate scientific data for the formulation / amendment of environmental policies. However, traditional indoor simulation experiments usually rely on devices with simplified processes and single conditions, and the results and conclusions obtained are often far from the real environment, which may hinder or even mislead the effective disposal of environmental pollution. Therefore, it is necessary to develop simulation experiment devices that are consistent with real environmental conditions to ensure the accuracy of the results of environmental process simulation and analysis.

[0003] So far, there is no simulation device specifically for site soil pollution at home and abroad. Site soil pollution refers to the phenomenon that the migration and transformation of pollutants in soil caused by processes such as industrial / agricultural production, accidental leakage, and natural disasters pose potential environmental risks or actual hazards to the ecological environment, human health, and land use. The migration and transformation of pollutants in soil are simultaneously affected by the coupling of multiple fields such as gravity field, seepage field, chemical field, and biological field, resulting in the characteristics of site soil pollution such as concealment, hysteresis, accumulation, and difficulty in remediation. The migration of soil pollutants is mainly affected by the gravity field and the seepage field, while the transformation is mainly affected by the chemical field and the biological field. At present, most studies are based on single processes under simulated conditions, such as beaker experiments and soil column experiments, which cannot reproduce the migration and transformation processes of pollutants under the coupling of multiple fields in the real soil environment. This greatly hinders the accurate understanding of the environmental fate and risk of pollutants in site soil. Therefore, it is urgent to establish a simulation device for the migration and transformation of soil pollutants under the coupling of multiple fields.

[0004] In summary, the existing soil pollutant migration and transformation simulation experiment devices have the following problems and defects: first, the coupling simulation of action fields is insufficient, and the multiple effects of gravity field, seepage field, chemical field, and biological field on the migration and transformation of pollutants are not fully considered; second, the structure of the simulation device is mainly designed as a whole, which makes it difficult to simulate the soil water-soil-biological multi-medium structure under the coupling of multiple fields; third, the sample preparation for simulation experiments does not fully consider the long-term continuous spatiotemporal sequence, and the original environment of the system is easily damaged during sampling, leading to distorted analysis data or limited results.

[0005] To solve the above problems and shortcomings, it is necessary to simultaneously integrate the dynamic interactions of gravity field, seepage field, chemical field and biological field, and develop a condition-controllable micro-simulation system (i.e., microcosm system) and its devices. The microcosm system needs to accurately simulate the material transfer and exchange across the soil-water-biological multi-media interface, and maintain the balance of multi-media cross-interface behavior for a long time. In addition, to ensure the accuracy of chemical and biological analysis, the microcosm system needs to ensure a certain amount of in-situ sample volume, avoid interference between samples caused by sampling and testing, and coordinate multi-dimensional heterogeneous spatiotemporal data.

[0006] Therefore, in response to the above-mentioned problems, the present invention proposes a soil pollutant migration and transformation simulation microcosm system and device, which simulates the environmental process of soil pollutants in contaminated sites to guide the process mechanism research of site pollution, environmental risk prediction, remediation technology development and environmental policy formulation / revision. Summary of the Invention

[0007] In order to overcome the problems of insufficient field coupling simulation in existing soil pollutant migration and transformation simulation experimental devices, the structure of the simulation device is mainly based on integrated design, which makes it difficult to simulate the multi-field coupled soil water-soil-organism multi-media structure, and the sample preparation of the simulation experiment does not fully consider the long-term continuous time and space sequence, and the original environment of the system is easily destroyed during sampling, resulting in distortion of analysis data or limited results, the present invention proposes a soil pollutant migration and transformation simulation microcosm system and device.

[0008] The technical solution of the present invention is: a soil pollutant migration and transformation simulation microcosm system, including: a microcosm system for simulating the soil environment of a contaminated site and examining the individual and coupled effects of gravity field, seepage field, chemical field and biological field; multiple functional module units, including a periodic precipitation unit, a temperature control unit, a time-space sequence sample preparation unit and a continuous undisturbed sampling unit.

[0009] Preferably, the object of simulation of the microcosm system is the soil environment of the contaminated site, focusing on the multiple fields that affect the migration and transformation of pollutants, including: gravity field, after the pollutants enter the soil environment, they migrate in the vertical direction of the soil under the action of gravity; seepage field, pollutants in the soil environment migrate with the isotropic diffusion of soil water, and the vertical movement is mainly affected by gravity and pressure difference. Downward seepage and upward capillary rise may occur. Under the influence of concentration gradient and pressure difference, seepage may also occur under the influence of soil stratification and cracks. Molecular diffusion is mainly affected by concentration gradient and adsorption / desorption of soil colloids; chemical field, pollutants in the soil environment are affected by redox potential, pH value, coexisting substances, etc., and undergo chemical reactions to generate intermediate products; biological field, pollutants in the soil environment are affected by the life activities of microorganisms, plants or animals, and undergo biological metabolism / transformation, absorption, fixation and other processes.

[0010] Preferably, the functional module unit reflects the effectiveness of the microcosm system in simulating the migration and transformation process of soil pollutants in contaminated sites, specifically including: a periodic precipitation unit, which simulates the precipitation conditions of the contaminated site, and regulates the changes in the moisture gradient of the soil profile and the soil interstitial water content by controlling the rainfall intensity, frequency and duration. At the same time, the unit supports non-uniform precipitation patterns, such as short-term heavy rain and intermittent light rain, and simulates the effects of alternating dry and wet cycles on the adsorption-desorption-dissolution-migration of pollutants; a temperature control unit, which simulates the environmental temperature fluctuations of -20°C to 50°C in the contaminated site, and together with the periodic precipitation unit realizes extreme climate scenarios such as seasonal freeze-thaw, high temperature drought, etc., and precipitation-temperature synergistic stress, which can simulate the multi-level action mechanism of temperature on microbial activity, pollutant diffusion coefficient and soil physical structure (crack development); a spatiotemporal sequence sampling unit, which constructs an equivalent acceleration environment to simulate the migration and transformation process of soil pollutants over a long period of time. Through the modular reactor array, complete environmental space samples at continuous time nodes (different exposure durations) can be prepared simultaneously, including components such as stratified soil, pore water, and rhizosphere micro-regions, retaining the continuous three-dimensional spatial characteristics of pollutant migration and transformation, such as pollutant diffusion zones and degradation fronts, while maintaining the metabolic activity of microbial communities in situ; continuous undisturbed sampling units, all samples are prepared and extracted and collected in parallel, realizing independent extraction of parallel samples throughout the entire cycle, and a single sampling will not disturb other samples in the continuous time and space sequence.

[0011] Preferably, a soil pollutant migration and transformation simulation microcosm device includes: the system device is a medium carrier of the microcosm system, and integrates the system functional modules at the same time, and is assembled from multiple materials and components.

[0012] Preferably, the device includes: a soil column array structure, which is the main body of the device, and each soil column in the array structure is a sample of a complete environmental space; a timed and quantitative precipitation component, which is located directly above the soil column array and contains a timer switch, a sprinkler nozzle, a peristaltic pump and a water tank; a pollutant dosing component, which adds pollutants to the soil column array in a quantitative manner at the same time; an assembled long-time continuous simulation component, which determines the number of soil columns of the main body according to the time requirements and sampling frequency of the simulation experiment, and sets a leachate collection unit for each soil column; an extraction-type soil column non-destructive sampling component, which extracts one soil column each time sampling, and the soil columns extracted in the previous batch have no effect on the samples in the soil columns to be extracted in the next batch; a segmented chemical or biological analysis, in which the soil columns extracted for each sampling can be evenly divided longitudinally according to the test requirements for subsequent chemical or biological analysis.

[0013] Preferably, the materials include soil columns, soil column fillings, and leachate collectors. The shell material of a single soil column is stainless steel or acrylic plate (plexiglass plate), and the shape can be a cylindrical tube or a rectangular tube with no seals on the top and bottom. The size is designed according to the minimum soil sample amount required for the planned analysis (V=A×h, A is the bottom area of ​​the soil column, and h is the height of the soil column). The soil column filling is air-dried and sieved contaminated site soil, or artificial transparent soil, etc. The total mass M of the filling is designed according to the minimum soil sample mass M' required for the planned analysis, M>N×M' (N times parallel); the shell material of the leachate collector is stainless steel or acrylic plate (plexiglass plate), etc., and the shape can be a cylinder or a rectangular tube with an open top surface, and the inner diameter of the opening is slightly larger than the outer diameter of the bottom surface of the soil column.

[0014] As a preference, the soil column array structure is the main body of the device, and the array structure accommodates n×m soil columns in total, each soil column is a sample of a complete environmental space, and the sample number is recorded as s ij , where i=1, 2, …, n; j=1, 2, …, m.

[0015] Preferably, the pollutant dosing component comprises a liquid storage tank, a pulse injection pump and a multi-channel distribution valve. The pulse injection pump can set a single injection volume of 0.1-100 mL and an injection interval time, and is connected to the dosing point of the device body through the multi-channel distribution valve.

[0016] As a preference, the assembled long-time continuous simulation component determines the expected total number of sampling times X according to the time requirements and sampling frequency of the simulation experiment, and sets the number of soil columns of the main body, where X≤n×m, which is the number of the sequence number s ij One-to-one corresponding long time series soil column samples s x , where x = 1, 2, …, X, set the sampling time batch, and set the leachate collection unit for each soil column. The collected soil column leachate sample is recorded as f x , where x=1, 2, …, X.

[0017] As a preference, for the segmented chemical or biological analysis, the soil column extracted for each sampling can be evenly divided into Y segments longitudinally according to the test requirements, and each segment is recorded as sample s xy , for subsequent chemical or biological analysis, by cross-comparing the xy The chemical or biological analysis results can be used to analyze the migration and transformation process of pollutants under multi-field coupling, where x=1, 2, …,X and y=1, 2, …,Y.

[0018] The beneficial effects of the present invention are as follows: 1. By integrating dynamic interactive simulations of gravity, seepage, chemical, and biological fields, the present invention accurately quantifies the synergistic mechanism of multi-field coupling on pollutant migration and transformation under controllable microcosm conditions, thereby overcoming the limitations of single-process simulations of traditional devices and directly revealing the dynamic correlation of multiple field effects in the "black box" of soil pollution. 2. The periodic precipitation and temperature control of modular functional units can accurately reproduce the precipitation patterns of heavy rain / light rain, seasonal temperature fluctuations, and extreme climates in real sites. Combined with soil column arrays filled with real contaminated soil or transparent artificial soil, the water-soil-organism multi-media cross-interface behavior is synchronously reconstructed, filling the data gap between laboratory simulations and real site environments, and supporting high-confidence simulation of pollution processes. 3. Complete environmental samples at continuous time nodes are prepared in parallel through spatiotemporal sequence sample preparation units. Combined with extractive non-destructive sampling technology, full-cycle independent sampling is achieved, thereby avoiding the damage to the system structure caused by traditional sampling. Then, three-dimensional distribution data of pollutants are obtained through longitudinal segmentation, thereby ensuring the data fidelity of long-term migration and transformation processes, providing an irreplaceable spatiotemporal continuous evidence chain for environmental behavior prediction, risk modeling, and policy formulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Shown is a schematic diagram of the system framework of the present invention; Figure 2 Shown is a schematic diagram of the microcosm system design and device construction of the present invention; Figure 3 Shown is a schematic diagram of the microcosm system simulation experiment process of the present invention; Figure 4 Shown is a schematic diagram of the timing and quantitative rainfall device of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0021] See also Figure 1The present invention provides an embodiment: a soil pollutant migration and transformation simulation microcosm system and its device, including: S1, a multi-field coupled soil microcosm system, a microcosm system that simulates the soil environment of a contaminated site, and comprehensively examines the individual effects of each field such as the gravity field, seepage field, chemical field and biological field, as well as the coupling effects of multiple fields; S2, the functional modules of the microcosm system, including a periodic precipitation unit, a temperature control unit, a time-space sequence sample preparation unit, a continuous undisturbed sampling unit, etc.; S3, a microcosm system device, as a medium carrier of the above-mentioned microcosm system, integrates the above-mentioned system functional modules, and is assembled from multiple materials and components, which can realize functions such as timed and quantitative precipitation, pollutant addition, assembled long-time continuous simulation, extraction-type non-destructive soil column sampling and equal-segmented chemical or biological analysis.

[0022] See also Figure 2 In S1, the present invention provides a multi-field coupled soil pollutant microcosm system, specifically including: S101, taking the polluted site as the simulation object, analyzing the pollutant emission and its fate in the soil environment; S102, taking the real pollution situation as the conceptual prototype, constructing a microcosm system composed of multiple modules (A, B, C, D, etc.), each module is used to simulate different environmental conditions, and simulation experiments are carried out simultaneously. Each module examines the effects of gravity field, seepage field, chemical field and biological field on the migration and transformation of pollutants, and the simulation results are compared with each other.

[0023] In S2, the present invention provides a functional module unit of the microcosm system, specifically including: S201, each module is relatively independent, constructing an equivalent acceleration environment, which can respectively simulate different environmental conditions such as humidity, rainfall, blank control, and temperature. An array of soil column reactors (inner liner) is set up to simulate the migration and transformation process of soil pollutants in a long-term sequence; S202, each soil column reactor (inner liner) is parallel to each other and is used for parallel preparation and extraction sampling of samples. A single sampling will not disturb other samples in the continuous time and space sequence. Each reactor simulates the coupling effect of gravity field, seepage field, chemical field and biological field. Among them, the seepage field is mainly activated by precipitation events, and the gravity field and seepage field are coupled to form a hydrodynamic field.

[0024] In S3, the present invention provides a microcosm system device, specifically including: S301, multiple cylindrical containers of identical structure and size, together forming a cylindrical array, which is the main body of the device, accommodating a total of n×m soil columns (n ​​rows and m columns), each of which can provide a sample of a complete soil profile, and the sample number is recorded as s ij(i=1, 2, …, n; j=1, 2, …, m), the shell material is stainless steel or acrylic plate, etc., the column container shape can be a cylindrical tube or a rectangular tube (the upper and lower sides are not sealed), the size is designed according to the minimum soil sample required for the planned analysis (V=A×h, A is the bottom area of ​​the soil column, h is the height of the soil column), the soil column filling is air-dried and sieved contaminated site soil, or artificial transparent soil, etc. The total mass M of the filling is designed according to the minimum soil sample mass M' required for the planned analysis, M>N×M' (N times parallel); S302, detachable surface, is used to segment the sample after extraction. After disassembly, the soil column can be evenly divided into Y sections (layers) longitudinally according to the test requirements, and each section (layer) is recorded as sample s xy (y = 1, 2, …, Y) for subsequent chemical or biological analysis. S303, rivets or screws, used to attach the removable surface. Multiple rivets or screws are installed to ensure the airtightness of the side of the cylindrical container. S304, leachate collector, the outer shell is made of stainless steel or acrylic sheet (plexiglass sheet), and the shape can be cylindrical or rectangular (open top), with the inner diameter of the opening slightly larger than the outer diameter of the soil column base.

[0025] See also Figure 3 In step S3, the present invention provides a multi-field coupled microcosm system device, which specifically includes: S305, quantitatively adding pollutants to simulate pollutant emissions in actual sites; S306, timed and quantitative water injection, located directly above the device body, and the precipitation cycle is set according to the equivalent accelerated environmental conditions of the microcosm system; S307, continuous sampling until the end of the test, and the samples can be used to analyze the pollutants and their transformation products (chemical field), microorganisms (biological field), pore water and seepage fluid characteristics (hydrodynamic field formed by the coupling of gravity field and seepage field).

[0026] See also Figure 4 The present invention provides a timed and quantitative water injection device, which specifically includes: S203, a periodic precipitation unit corresponding to the water injection device, including a timer switch, a sprinkler nozzle, a peristaltic pump and a water storage tank; S308, a water storage tank, which stores and prepares rainwater; S309, a timer switch, which can control the frequency of precipitation events; S310, a peristaltic pump, which is used to pump simulated rainwater; S311, a water distributor, which is used to evenly distribute the simulated rainwater to each soil column reactor; S312, a sprinkler head, which is used to put the simulated rainwater into the designated position of the soil column reactor.

[0027] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0028] According to an embodiment of the present application, a microcosm simulation system and device for the migration and transformation of PFAS in the soil environment of a contaminated site are established, the design concept of the microcosm system relies on typical site characteristics, the rainfall is accurately controlled to simulate soil water infiltration through modular units, and key factors such as maintaining a specific microenvironment temperature are controlled, a micro simulation system reflecting actual site conditions is constructed, and the device simulates the complex environmental processes of the actual contaminated site through a soil column of laboratory scale.

[0029] To simulate the migration behavior of PFAS in the soil of a contaminated site under complex environmental conditions, as shown in A, B, C, D, etc. Figure 2 The modules A, B, C, D, etc. shown simulate different conditions such as rainfall, air temperature, light, pollution load and blank control, etc. The influence of various environmental factors on the migration and transformation of PFAS is studied. Each module is an independent experimental unit, which can flexibly adjust parameters according to research needs and provide diversified simulation parameters.

[0030] The microcosm system device can accurately control rainfall to simulate natural rainfall processes, thereby studying the migration behavior of PFAS under different rainfall events; by simulating soil water infiltration processes, the distribution and migration path of PFAS in the soil profile can be revealed, laying a foundation for studying the interaction between PFAS and soil particles and pore water. Considering that environmental temperature is an important factor affecting the reaction rate and migration of chemicals, the design also strictly controls it to simulate the influence of seasonal changes on the migration behavior of PFAS.

[0031] The microcosm system device selects organic glass material, and the inner container size of the soil column unit is 2.8cm x 2.8cm x 1.2m, with a thickness of 8mm. Not only the specific needs of the experiment are considered, but also the convenience and efficiency of sampling during the experiment are concerned. Specifically, the width of 2.8cm can perform large-scale experiments in a compact space while ensuring the independence and integrity of each soil column. The wall thickness of 0.8cm is sufficient to withstand soil pressure, ensuring the durability and stability of the device during the experiment. In addition, organic glass is selected as the material of the soil column inner container because of its excellent transparency and chemical corrosion resistance. The transparent material ensures that physical and biological changes in the soil, such as root development and water distribution, can be observed during the experiment. The chemical corrosion resistance ensures the durability of the soil column when it comes into contact with various soils and chemical treatments, thereby ensuring the long-term stability and reliability of the experiment.

[0032] In order to simulate the dark conditions below the soil surface in a real environment and facilitate observation, the microcosm system device is designed with a double-layer structure consisting of a plexiglass shell covered with a light-shielding sleeve. This design allows researchers to create a dark environment when needed to simulate environmental processes deep in the soil or in darkness, which is particularly important for studying certain soil microbial processes that require light protection. At the same time, the light-shielding sleeve can also be removed as needed for observation and maintenance. The flexible design enables the device to adapt to various experimental conditions and environmental requirements.

[0033] The microcosm system device also takes into account temperature control and humidity maintenance. The thermal stability of the plexiglass material and the insulating properties of the light-shielding sleeve can help maintain the microclimate inside the soil column and reduce the impact of external temperature fluctuations on the experimental results. To further control the microenvironment temperature of the soil layer, the temperature of the soil layer can be maintained constant by using heating or cooling equipment to simulate the impact of different seasons or climate changes on the migration and transformation of PFAS.

[0034] Since soil is not a homogeneous entity, its physical and chemical properties show significant vertical gradient changes along the depth direction. Among them, the redox potential (Eh) profoundly affects the chemical and biological fields, and it generally decreases with increasing depth in the soil profile: the oxygen content in the surface soil is relatively high, and the Eh value is high, providing a suitable environment for aerobic microorganisms; as oxygen penetration decreases and organic matter decomposition consumes oxygen, the Eh value begins to decrease, and a microaerobic or facultative anaerobic environment may appear. Traditional soil simulation experiments often ignore the above-mentioned Eh gradient, which may lead to simulation distortion. The microcosm system device constructs and controls the Eh gradient that varies with depth by controlling water saturation, ventilation rate, and adding electron acceptors / donors, etc., so as to more realistically reflect the soil environment of the contaminated site and form a chemical and biological field close to the real situation.

[0035] In order to simulate the natural infiltration and retention of soil moisture, the microcosm system device is designed with a sand filter layer at the bottom, and fine sand with large, medium and small particles is laid from bottom to top. This not only prevents soil loss, but also plays a role in water storage. The volume of the sand filter layer is designed according to the maximum water storage capacity vmax of the longest operation time of the microcosm, ensuring that when simulating rainfall events, the microcosm system device can accommodate and release water and simulate the hydrological process under natural conditions.

[0036] In the specific experimental operation, a special soil sampling device is required to collect the soil columns from the pilot-scale site as a whole and transfer them to the soil column system to ensure that the soil samples in the microcosm system device can represent the stratification conditions of the actual site. In order to simulate real rainfall weather, the microcosm system device adopts a precise sprinkler irrigation system consisting of a peristaltic pump, a water storage tank and a sprinkler control device. This sprinkler irrigation system can realize intelligent control of precipitation.

[0037] Soil samples are collected regularly from different depths of the soil column. These samples will be used to analyze the concentration and distribution of PFAS. To ensure the accuracy of sampling, the microcosm system device avoids the traditional excavation or drilling sample collection method, but adopts a more sophisticated technology. When sampling is needed, researchers only need to open the detachable surface of the soil column to directly obtain soil samples at the required depth. This method minimizes interference with the soil structure, ensures the representativeness of the sample and the accuracy of the experimental data. By analyzing these non-destructively collected samples, the migration path of PFAS in the soil can be tracked in detail, and its stability and bioavailability under different environmental conditions can be evaluated. In addition, the soil column design of the microcosm system can also introduce microorganisms or some small plants into the experiment to study their effects on the migration and transformation of PFAS. This versatile soil column design enables us to more comprehensively understand the behavior of PFAS in the multi-media system of site soil, providing conditional support for the management and remediation of contaminated sites.

[0038] In the description of the present invention, unless otherwise specified, the meaning of "field" is the process that acts on the migration and transformation of pollutants; the concepts of describing "field" such as "gravity field", "seepage field", "chemical field", "biological field" and "hydrodynamic field" are only for the convenience of describing the present invention and simplifying the description. Similar expressions can also include physical fields, (static) electric fields, chemical substance transmission fields, solute migration fields, and biological reaction (degradation) fields, rather than indicating the neglect of specific environmental processes, and therefore cannot be understood as a limitation on the present invention.

[0039] The embodiments of the present invention can be implemented for various site pollution scenarios and target pollutants through system modeling and various material processing and architectures with equivalent performance. Ordinary technicians in this field can understand that the above-mentioned systems and devices can be implemented in various scenarios.

[0040] The above are merely preferred embodiments of the present invention and do not limit the present invention in any other form. Any technician familiar with the present invention may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A soil pollutant migration and transformation simulation microcosm system, characterized in that: These include: a microcosm system, which is used to simulate the soil environment of a contaminated site and examine the individual and coupled effects of gravity, seepage, chemical, and biological fields; Multiple functional module units, including periodic precipitation unit, temperature control unit, spatiotemporal sequence sampling unit and continuous undisturbed sampling unit.

2. A soil pollutant migration and transformation simulation microcosm system according to claim 1, characterized in that: The object of simulation of the microcosm system is the soil environment of the contaminated site, focusing on the multiple fields that affect the migration and transformation of pollutants, including: the gravity field, which is used to drive the vertical migration of pollutants in the soil; the seepage field, which is used to drive the diffusion of pollutants in all directions with soil water; the chemical field, which drives the chemical transformation of pollutant parent substances and their metabolites; and the biological field, which drives the biological transformation of pollutant parent substances and their metabolites.

3. A soil pollutant migration and transformation simulation microcosm system according to claim 1, characterized in that: The functional module units reflect the effectiveness of the microcosm system in simulating the migration and transformation process of soil pollutants in contaminated sites, specifically including: a periodic precipitation unit, which simulates the precipitation conditions of the contaminated site and can regulate soil moisture and soil interstitial water content; a temperature control unit, which simulates the temperature conditions of the contaminated site and realizes the simulation of seasonal or extreme weather phenomena together with the periodic precipitation unit; a spatiotemporal sequence sample preparation unit, which simulates the migration and transformation process of soil pollutants in a long time series and can prepare complete environmental space samples at continuous time nodes; a continuous undisturbed sampling unit, in which all samples are prepared and extracted in parallel, and a single sampling will not disturb other samples in the continuous spatiotemporal sequence.

4. A soil pollutant migration and transformation simulation microcosm device, using a soil pollutant migration and transformation simulation microcosm system according to any one of claims 1 to 3, characterized in that: The system device is a medium carrier of the micro-universe system, and integrates system function modules at the same time, and is assembled from multiple materials and components.

5. The soil pollutant migration and transformation simulation microcosm device according to claim 4, characterized in that: It includes: a soil column array structure, which is the main body of the device, and each soil column in the array structure is a sample of a complete environmental space; a timed and quantitative precipitation component, which is located directly above the soil column array and contains a timer switch, a sprinkler nozzle, a peristaltic pump and a water tank; a pollutant dosing component, which adds pollutants to the soil column array in a quantitative manner at the same time; an assembled long-time continuous simulation component, which determines the number of soil columns in the main body according to the time requirements and sampling frequency of the simulation experiment, and sets a leachate collection unit for each soil column; an extraction-type soil column non-destructive sampling component, which extracts one soil column each time sampling, and the soil columns extracted in the previous batch have no effect on the samples in the soil columns to be extracted in the next batch; segmented chemical or biological analysis, the soil columns extracted for each sampling can be evenly divided longitudinally according to the test requirements for subsequent chemical or biological analysis.

6. The soil pollutant migration and transformation simulation microcosm device according to claim 4, characterized in that: The materials include soil columns, soil column fillings and leachate collectors. The shell material of a single soil column is stainless steel or acrylic plate, and the shape can be a cylindrical tube or a rectangular tube with no upper and lower seals. The size is designed according to the minimum soil sample amount required for the planned analysis. The soil column filling is air-dried and sieved contaminated site soil or artificial transparent soil. The total mass of the filling is designed according to the minimum soil sample mass required for the planned analysis. The shell material of the leachate collector is stainless steel or acrylic plate, and the shape can be a cylinder or a rectangular tube with an open top surface. The inner diameter of the opening is slightly larger than the outer diameter of the bottom surface of the soil column.

7. The soil pollutant migration and transformation simulation microcosm device according to claim 5, characterized in that: The soil column array structure is the main body of the device. The array structure contains n×m soil columns. Each soil column is a sample of a complete environmental space. The sample number is denoted as s. ij , where i=1, 2, …, n; j=1, 2, …, m.

8. The soil pollutant migration and transformation simulation microcosm device according to claim 5, characterized in that: The pollutant dosing component includes a liquid storage tank, a pulse injection pump and a multi-channel distribution valve. The pulse injection pump can set a single injection volume of 0.1-100 mL and an injection interval time, and is connected to the dosing point of the device body through the multi-channel distribution valve.

9. The soil pollutant migration and transformation simulation microcosm device according to claim 5, characterized in that: The assembled long-time continuous simulation component determines the total number of sampling times X according to the time requirements and sampling frequency of the simulation experiment, and sets the number of soil columns of the main body, where X≤n×m, which is the number of the sequence number s ij One-to-one corresponding long time series soil column samples s x , where x = 1, 2, …, X, set the sampling time batch, and set the leachate collection unit for each soil column. The collected soil column leachate sample is recorded as f x , where x=1, 2, …, X.

10. The soil pollutant migration and transformation simulation microcosm device according to claim 5, characterized in that: For the segmented chemical or biological analysis, the soil column extracted each time can be evenly divided into Y sections longitudinally according to the test requirements, and each section is recorded as sample s xy , for subsequent chemical or biological analysis, by cross-comparing the xy The chemical or biological analysis results can be used to analyze the migration and transformation process of pollutants under multi-field coupling, where x=1, 2, …, X and y=1, 2, …, Y.

Images