Mine wasteland heavy metal stabilization and vegetation reconstruction cooperation method

Abstract

The invention relates to the technical field of combined pollution regulation and control, in particular to a mining wasteland heavy metal stabilization and vegetation reconstruction synergistic method which comprises the steps that a composite passivator is evenly laid on the surface layer of a mining wasteland, the composite passivator comprises modified biochar and a mineral binder, and an initial passivation layer is formed; planting halophytic tolerance vegetation on the surface of the initial passivation layer, and enabling the root system of the vegetation to penetrate through the passivation layer and extend to the polluted substrate; inducing the pore structure of the passivator to recombine by using organic acid secreted by the root system of the halophytic vegetation, and synchronously complexing heavy metal ions and salt ions to form a stabilized rhizosphere microdomain; introducing salt-tolerant mycorrhizal fungi into the stabilized rhizosphere microdomain, wherein the salt-tolerant mycorrhizal fungi and halophytic vegetation are symbiotic to form a heavy metal barrier. According to the method, the space matching precision of the mycorrhiza inoculation area is improved, the cooperative symbiosis capability of the root system in the heterogeneous salt-hypochondrium environment is enhanced, the method has the advantages of being accurate in modeling, quick in response, high in operability and the like, and good engineering popularization potential and ecological reconstruction value are embodied.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of complex pollution regulation, and in particular to a mine wasteland heavy metal stabilization and vegetation reconstruction synergistic method. BACKGROUND

[0002] In the salinized soil area, the increase of conductivity will seriously inhibit the growth of plant root system and its microbial interaction ability, especially affecting the colonization efficiency and growth-promoting function of mycorrhizal fungi. The traditional mycorrhizal inoculation method is mostly based on fixed dose or empirical regression model for treatment, ignoring the spatial heterogeneity of soil environment and the dynamic evolution characteristics of conductivity. The common microbial application strategy in the current method is difficult to respond to local soil salt disturbance, resulting in uneven growth-promoting effect and mycorrhizal network fracture in the inoculation area, thereby reducing the utilization efficiency of inoculant and the improvement effect of plant salt tolerance.

[0003] The prior art has obvious deficiencies in the following aspects: lack of response mechanism to the change trend of soil conductivity, unable to realize dynamic regulation of mycorrhizal application amount and action time; without fully considering the role of multi-dimensional spatial factors such as microbial diffusion path and rhizosphere growth-promoting ability distribution, limiting the model in the promotion and application in the actual field; most algorithm models lack physical and physiological basis for setting key regulation parameters, lack mathematical characterization of biological mechanisms such as growth-promoting suitability index and root zone mutation rate, and are difficult to accurately describe the mycorrhizal response process, therefore, it is urgent to build a regulation model that can comprehensively consider the salt stress intensity, growth-promoting feedback trend and microenvironment evolution characteristics, to improve the spatio-temporal adaptability and stability of mycorrhizal application strategy under salt stress conditions. SUMMARY

[0004] The present application provides a mine wasteland heavy metal stabilization and vegetation reconstruction synergistic method.

[0005] The mine wasteland heavy metal stabilization and vegetation reconstruction synergistic method comprises the following steps: S1: uniformly laying a composite passivation agent on the surface of the mine wasteland, the composite passivation agent comprising modified biochar and a mineral binder, to form an initial passivation layer; S2: planting halophytic vegetation on the surface of the initial passivation layer, so that the root system of the vegetation penetrates the passivation layer and extends to the contaminated substrate; S3: using the organic acid secreted by the root system of the halophytic vegetation to induce the reorganization of the pore structure of the passivation agent, and simultaneously complexing heavy metal ions and salt ions, to form a stabilized rhizosphere microdomain; S4: introducing salt-tolerant mycorrhizal fungi into the stabilized rhizosphere microdomain, the salt-tolerant mycorrhizal fungi and the halophytic vegetation forming a heavy metal barrier in symbiosis.

[0006] Optionally, the S1 comprises: S11: Scanning the area with a UAV equipped with an XRF device to obtain the spatial distribution information of heavy metal concentration and soil salinity, and combining soil type correction to generate a pollution characteristic matrix; S12: According to the pollution characteristic matrix, a passivation agent proportioning function is established, considering the heavy metal concentration and salt level, and dynamically determining the proportion of biochar and binder at each location; S13: Input the proportioning result into the intelligent spreading equipment, mainly biochar in high pollution areas to improve adsorption performance, mainly binder in high salt areas to enhance structural stability, and perform partitioned laying as needed; S14: Adjust the laying thickness according to the pollution spatial gradient, appropriately thicken the area with severe pollution changes to enhance the local protection ability and inhibit pollution diffusion, construct an initial passivation layer thickness function, and calculate the initial passivation layer thickness.

[0007] Optionally, the S13 comprises: S131: According to the obtained composite passivation agent proportioning function value, judge the pollution dominant type of each coordinate point; when the proportioning value is greater than or equal to the set proportioning threshold value, it is determined as a heavy metal pollution dominant area, and modified biochar is preferentially used as the main component; when the proportioning value is less than the set proportioning threshold value, it is determined as a salt-affected dominant area, and mainly uses mineral binder to improve structural stability; S132: Input the partitioned proportioning information into the intelligent spreader control system, automatically adjust the material proportion according to the area type and perform differentiated laying, form adsorption function enhanced area in high heavy metal concentration area, and construct salt-resistant stable area in salt-enriched area, realize precise material delivery and function partition control.

[0008] Optionally, the S2 comprises: S21: Calculate the minimum penetration required for the vegetation root system to break through the passivation layer, combined with the initial passivation layer thickness, dry density and binder proportion; S22: Compare the minimum penetration required by the area with the inherent penetration of the vegetation root system, and select salt-tolerant vegetation that can meet the requirements, to realize the matching of type and layer conditions; S23: According to the position of the initial passivation layer and the substrate interface, appropriately increase the super-deep amount to ensure that the root system extends to the contaminated substrate to realize heavy metal absorption; S24: Inject high-pressure water flow at the planting hole bottom to form controllable micro-cracks, reduce root penetration resistance, and at the same time maintain the stability of the passivation layer structure.

[0009] Optionally, the S21 comprises: S211: According to the thickness, dry density and proportion of mineral binder of the initial passivation layer, comprehensively determine the main factors affecting the hardness of the layer, as input parameters for calculating the root penetration requirement; S212: Calculate the minimum penetration force required for the vegetation root to break through the initial passivation layer at each coordinate point.

[0010] Optionally, the S22 comprises: S221: Construct a database of inherent penetration force of halophytic vegetation roots covering different plant species and their typical penetration force ranges; S222: Compare the minimum root penetration force requirement value calculated for each region with the inherent penetration force of different vegetation in the database, and select candidate vegetation that can meet or exceed the requirement; S223: According to the comparison result, determine the appropriate halophytic vegetation type, so that the selected vegetation can successfully break through the initial passivation layer and complete the planting in the mechanical condition.

[0011] Optionally, the S3 comprises: S31: Obtain the concentration of organic acid through rhizosphere microdialysis device, and construct its spatiotemporal distribution model, comprehensively consider the metabolic characteristics of vegetation, secretion time peak and the inhibition effect of mineral binder, and reflect the difference of secretion intensity in different regions; S32: Dynamically control the pore structure of passivation agent according to the change of organic acid concentration, control the expansion range of pore combined with the pollution load degree and the reaction efficiency of material, and introduce the limiting function to prevent the over-expansion of layer; S33: Construct a composite model considering heavy metal adsorption and salt interference inhibition, optimize the simultaneous fixation efficiency based on specific surface area synergism and dynamic pore response; S34: Set the triple index of fixation efficiency, pore expansion and secretion uniformity as the basis for judging whether the stabilized rhizosphere microdomain is stably formed, and ensure the long-term effective operation of the passivation structure.

[0012] Optionally, the S32 comprises: S321: According to the real-time concentration level of rhizosphere organic acid, combined with its reaction efficiency on biochar material, calculate the pore diameter growth rate of passivation agent, and introduce pollution load weight to preferentially cause structural reorganization in areas with serious pollution; S322: On the basis of calculated pore expansion, use hyperbolic tangent function to nonlinearly limit the deformation amplitude, prevent the passivation layer structure from losing stability due to excessive pore expansion.

[0013] Optionally, the S4 comprises: S41: Dynamically calculate the survival rate of mycorrhizal spores in salt-tolerant mycorrhizal fungi inoculant according to the salt concentration and pore reorganization rate of the region; S42: According to the rhizosphere complexing efficiency and the spatial distribution of pollutants, adjust the application amount of salt-tolerant mycorrhizal fungi inoculant in different regions, and guide the mycelium to expand preferentially to high-risk pollution areas; S43: Integrate the mycelium density, length and the change of pore structure, evaluate whether the barrier built by mycelium has the ability to effectively block the migration of heavy metals; S44: When the barrier effectiveness meets the standard, the mycelium structure of salt-tolerant mycorrhizal fungi is stable, and the complexing efficiency continues to increase, it is determined that an effective heavy metal barrier has been formed.

[0014] Optionally, the S42 comprises: S421: The application amount of salt-tolerant mycorrhizal fungi inoculant is adjusted by exponential weighting based on the reference application amount, combined with the current regional di-ion complexing efficiency, to increase the application intensity in low-efficiency microdomains and enhance the colonization potential of salt-tolerant mycorrhizal fungi mycelium; S422: According to the spatial Laplace gradient of heavy metal pollutants, a gradient response function is introduced to dynamically correct the application strategy of salt-tolerant mycorrhizal fungi inoculant, so that the application amount of mycelium at the pollution front is enhanced, and the spatial expansion of salt-tolerant mycorrhizal fungi mycelium to high-risk areas is optimized.

[0015] The beneficial effects of the present application are: The present application proposes a salt-tolerant mycorrhizal fungi inoculant application method based on the regional conductivity evolution trend and the driving of the growth-promoting feedback function. For the first time, a local growth-promoting suitability index and a regional conductivity co-regulation mechanism are introduced, effectively establishing a nonlinear mapping relationship between the response intensity of the inoculant and the conductivity disturbance degree. At the same time, with the help of time gradient enhancement factor and rhizosphere mutation rate term, the local salt change rate is dynamically perceived, so as to realize the adaptive adjustment of the application intensity and timing of the inoculant. Compared with traditional methods, the spatial matching accuracy of the mycorrhizal inoculation area is significantly improved, and the symbiotic ability of the root system in a heterogeneous salt stress environment is enhanced.

[0016] The present application realizes the risk control of misapplication in extreme salt damage areas by introducing a nonlinear inhibition term and a saturation type enhancement function. The method can be widely applied in the remediation of saline land and the management of facility agriculture, and has significant advantages such as accurate modeling, sensitive response and strong operability, and has good engineering popularization potential and ecological reconstruction value. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only a part of the present application, and other drawings can also be obtained by those skilled in the art without creating any inventive labor.

[0018] Fig. 1 The method flowchart of the embodiment of the present application; Fig. 2 The penetration regulation diagram of the embodiment of the present application. DETAILED DESCRIPTION

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Those skilled in the art may employ other alternative methods to implement some well-known technologies; moreover, the accompanying drawings are only for more specific description of the embodiments and are not intended to specifically limit the present invention.

[0020] like Figs. 1-2 As shown, the synergistic method for heavy metal stabilization and vegetation reconstruction in mine waste sites includes the following steps: S1: A composite passivating agent, including modified biochar and mineral binder, is uniformly laid on the surface of the abandoned mine land to form an initial passivation layer; S1 specifically includes: S11: By using a drone equipped with an X-ray fluorescence spectrometer (XRF) to conduct low-altitude scanning of mining wastelands, the levels of heavy metal pollution and salinity accumulation at different geographical locations were obtained, and a pollution characteristic matrix was constructed, including a spatial distribution matrix of heavy metal pollution. and salt distribution matrix , is represented as: ; ; in, Coordinates The measured concentration of the i-th heavy metal at a given location, ranging from 0 to 1000, is based on the common heavy metal accumulation levels in mine wastelands and covers different scenarios from mild to severe pollution. σ is the pollution diffusion coefficient, reflecting the intensity of heavy metal diffusion in tailings particles and soil media during wind erosion, water erosion, or infiltration migration. Its value ranges from 0.1 to 1.0. When the soil particle structure is dense, the diffusion coefficient approaches 0.1; when the soil is loose or tailings dust is present, the diffusion coefficient can approach 1.0, indicating a high migration risk. EC is a measured value of electrical conductivity, obtained by measuring the electrical conductivity of the soil solution using a conductivity meter. It reflects the salinity level, with a value range of 0 to 2. 0-2 generally indicates non-saline soil; 2-4 indicates slight salinization; and values ​​greater than 4 indicate a salinization risk zone. Values ​​on mine slopes or in poorly drained areas can often reach above 10. This is a soil type correction factor used to correct for differences in conductivity measurements between different soil types. The value ranges from 0.8 to 1.2, with approximately 0.8 for clay, 1.2 for sandy soil, and 1.0 for loam. Sandy soil has large pores and high fluidity in saline solutions, resulting in lower conductivity readings and requiring amplification correction. Clay soil has high water retention and high ion exchange capacity, resulting in higher readings and requiring reduction correction. This is a spatial distribution matrix of heavy metal pollution, representing the heavy metal pollution load at each coordinate point, considering the superposition effect of different heavy metal element concentrations and their diffusion coefficients. is a salt distribution matrix, reflecting the soil salt level, which is calculated by the measured conductivity value combined with the soil type correction factor, so as to obtain the salt distribution pattern; S12: After obtaining the pollution distribution matrix, a regional differentiated matching function is constructed to guide the mass ratio of modified biochar and mineral binder at different coordinate points, considering both the relative intensity of heavy metal pollution and the salt concentration level, which is expressed as: ; wherein, is the mass ratio of modified biochar and mineral binder at the coordinate point , the larger the matching function value, the more biochar components the region needs; the smaller, the more mineral binder, is the heavy metal weight coefficient, with a value range of 0.6-0.8, mine wasteland is mainly affected by heavy metal pollution, so the weight coefficient of heavy metal needs to be kept at a high level, choosing the interval of 0.6-0.8 can highlight the dominance of heavy metals and avoid completely suppressing the role of salt factor, achieving balance, is the salt weight coefficient, with a value range of 0.4-0.6, salt has a significant impact on vegetation restoration and the stability of the initial passivation layer, but it is secondary to heavy metals, so its weight is slightly lower, set in the interval of 0.4-0.6, which can reflect the importance of the salt factor and ensure that it is not unbalanced with , the higher the relative intensity of heavy metal pollution, the more biochar is needed for adsorption, and the higher the conductivity area needs to increase the proportion of mineral binder to enhance salt resistance, by setting the weight coefficients of heavy metals and salt in two directions, the composition of the composite material is adjusted adaptively, making the passivation formula of different regions more targeted, is used to nonlinearly amplify the impact of salt level, ordinary linear relationship is not enough to reflect the risk of high salt environment, logarithmic function can process smoothly in low salt area and amplify rapidly in high salt area, so as to reasonably allocate the binder ratio; S13: input the composite passivation agent into the intelligent spreader and execute laying according to the matching function , realizing regional differentiated laying, when the matching value of a certain region is large, it means that heavy metal pollution dominates, and the region mainly uses modified biochar as the main material to form a high-efficiency passivation area with strong adsorption performance; when the matching value is small, it means that the salt is high or the heavy metal concentration is relatively low, and the mineral binder should be used as the main material to form a protective layer with stable structure and salt resistance, this regional laying strategy improves the overall efficiency and pertinence of passivation effect, which specifically includes: (1) when When the ratio of modified biochar is greater than or equal to 50%, a high adsorption zone is formed, the biochar has a strong specific surface area and functional group adsorption capacity, and the biochar should dominate in the high heavy metal area to maximize the fixation effect of cadmium, lead, zinc and other ions; (2) When , the ratio of mineral binder is greater than or equal to 50%, a high structural stability zone is formed, the mineral binder can combine with salt ions and improve the soil structure, and the layer stability and salt erosion resistance are improved, so the proportion needs to be increased in the high salt or low heavy metal concentration area; , wherein is the ratio function value, a larger value indicates that heavy metal pollution is dominant, and more biochar is needed to improve the adsorption performance, a smaller value indicates that the salt or heavy metal concentration is relatively low, and the proportion of mineral binder should be increased to enhance the structural stability, and 1 is a set ratio threshold, which can ensure that the two types of functional zones are clearly distinguished logically, and the intelligent spreading machine can automatically execute the control strategy; S14: To further improve the heavy metal migration control ability, after the ratio is completed, the laying thickness is adjusted according to the pollution space change trend, an initial passivation layer thickness function is constructed, and the initial passivation layer thickness is calculated, which can effectively prevent secondary migration or structural instability at the pollution front, improve the environmental adaptability and long-term stability of the overall initial passivation layer, and is represented as: ; , wherein is the reference thickness, the value range is 5-8, which can ensure the basic barrier function and avoid waste of materials and decrease of air permeability, is the Laplace operator, which represents the pollution space gradient, the value range is , a positive value indicates a high pollution area, and a negative value indicates a pollution dilution area, the pollution front and sharp change area are identified through the index, the thickness is dynamically adjusted, and spatial differentiation control is realized, , which represents the final initial passivation layer thickness formed at the coordinate point , the thickness is dynamically adjusted according to the pollution space gradient, the ordinary area maintains the reference thickness, and the high gradient pollution area is appropriately thickened by 20%-30% to improve the impermeability and structural stability, is the heavy metal pollution space distribution matrix.

[0021] S2: Planting salt-tolerant vegetation on the surface of the initial passivation layer, so that the vegetation roots penetrate the initial passivation layer and extend to the contaminated substrate; S2 specifically includes: S21: Based on the initial passivation layer thickness and the ratio of mineral binder derived from the ratio function, the minimum penetration force required for the vegetation roots to break through the initial passivation layer is calculated, and the influence of layer thickness, material dry density and binder ratio on hardness is considered at the same time, so that the penetration force requirement value at each coordinate point is obtained, and is represented as: ; ; in, It is a matching function. Coordinates The minimum penetration required by the root system of vegetation. This is the penetration resistance coefficient, reflecting the influence of soil texture on root penetration resistance. Sandy soil has a loose structure and relatively low resistance, so the coefficient is taken as a lower value of 1.2. Clay soil has a dense structure and strong cementation, resulting in high resistance, so the coefficient is taken as a higher value of 1.8. This refers to the dry density of the passivation layer, ranging from 1.2 to 1.5. This range represents the common dry density of tailings cover layers and improved soil. Too low a density will result in a loose layer, while too high a density will affect plant survival rates. The percentage of mineral binder mass reflects the hardness of the layer, with a value ranging from 0.3 to 0.7. Below 0.3, the layer strength is insufficient and prone to cracking; above 0.7, the layer is too hard, making it difficult for plants to penetrate. Therefore, it is usually controlled within the medium range. 0.5 is an adjustment coefficient that corrects the additive effect of mineral binder on the hardness of the layer. Mineral binder has a sublinear contribution to increasing the hardness of the layer. A value of 0.5 reflects its partial increase in root resistance, rather than a completely proportional amplification. The power exponent of 1.2 is used to describe the nonlinear relationship between resistance and thickness and density. As the thickness and density of the layer increase, the rate of increase in the penetration force required by the roots is greater than the linear relationship. 1.2 controls the nonlinear increase in resistance to avoid over-amplification of the calculation results. S22: Establish a root penetration database for halophyte-tolerant vegetation and compare the minimum penetration requirements of different regions with the inherent penetration of the vegetation. If the inherent root penetration of a certain vegetation is greater than or equal to the minimum requirement for that region, then the vegetation is determined to be suitable for planting in that region. This achieves the matching of vegetation type with the mechanical properties of the passivation layer, and selects plants that meet the requirements. Salt-tolerant vegetation, among which The minimum penetration force required for plant roots to break through the initial passivation layer. The inherent root penetration capacity of vegetation includes: (1) When When choosing, select *Salicornia*, a typical halophyte with a dense root system adapted to slightly saline and lightly polluted environments. Its penetrating power is suitable for thin layers, but it is difficult to penetrate thick, hard layers exceeding this value. Its inherent root penetrating power is approximately 3.3-4.3. *Salicornia* is a typical halophyte with a dense root system adapted to slightly saline and lightly polluted environments. Its penetrating power is suitable for thin layers, but it is difficult to penetrate thick, hard layers exceeding this value. *Salicornia* is suitable for thin layers. (2) When When choosing a plant, select Suaeda, whose root system has an inherent penetrating power of about 4.5-5.9. Suaeda has stronger root mechanical properties than sea pelt and can adapt to medium-thickness passivation layer environments. Suaeda is suitable for medium-thickness areas. (3) When When choosing Tamarix, its root system has an inherent penetrability of about 6.2-8.0. Tamarix has deep roots and strong lignification characteristics. Its roots can penetrate into high-hardness tailings or thick overburden, so it is suitable for the hardest and thickest areas, ensuring that the roots can successfully enter the contaminated matrix. Tamarix is ​​suitable for thick and hard layer areas. Here, 4.0 is the boundary threshold between the thin-layer zone and the medium-thickness zone. When the minimum root penetration force does not exceed 4.0, it usually corresponds to a region with a thinner passivation layer, lower density, or less binder content. These regions have less mechanical resistance, allowing the roots of *Salicornia* to penetrate smoothly and complete planting. Once the required penetration force exceeds 4.0, the penetration success rate of *Salicornia* will decrease significantly. Therefore, 4.0 is set as the boundary threshold between the thin-layer zone and the medium-thickness zone to ensure the suitability of vegetation selection with the layer conditions. 5.5 is the medium-thickness zone... The critical threshold between the medium thickness zone and the thick hard layer zone is defined as follows: when the minimum root penetration exceeds 5.5, the passivation layer exhibits a high thickness, dry density, and binder ratio, which is a typical thick hard layer zone. Suaeda with medium penetration can hardly penetrate further, and the root survival rate drops significantly. At this point, Tamarix's strong lignified root system and higher penetration are needed to ensure successful planting. Therefore, 5.5 is set as the critical threshold between the medium thickness zone and the thick hard layer zone to ensure the effective growth of different vegetation types under suitable mechanical conditions. S23: Determine the planting depth of the plants based on the interface location between the initial passivation layer and the underlying contaminated matrix. In addition to the baseline thickness, a certain amount of extra depth is added to ensure that the roots can effectively penetrate the initial passivation layer and enter the contaminated matrix area, so as to exert the function of heavy metal absorption, as shown below: ; in, Coordinates The actual planting depth of halophytes, i.e., the target depth to which the root system should extend, is crucial for ensuring that the roots can penetrate the initial passivation layer and further enter the contaminated substrate layer. This is a fundamental condition for achieving targeted remediation. The depth should not be too shallow, to avoid the roots remaining in the uncontaminated area, nor should it be too deep, to avoid increasing the difficulty of penetration or causing root rot. Coordinates The initial passivation layer thickness, ranging from 5 to 12, is used to cover areas contaminated with heavy metals and form a stable barrier layer. is a root penetration depth, and has a value range of 3-5, ensuring that the root extends to the contaminated substrate, and within the range, the root can stably penetrate the bottom boundary of the initial passivation layer and enter the contaminated substrate, while avoiding the root being suspended or stranded due to insufficient penetration or a too thick passivation layer, less than 3 may not effectively reach the pollution layer, and greater than 5 significantly increases the penetration burden, which is not conducive to the survival of the plant; S24: A pulse water needle is used to inject high-pressure water flow at the bottom of the planting hole to provide auxiliary action, and the water flow pressure is dynamically regulated, on the one hand, it is sufficient to form micro-cracks in the initial passivation layer to reduce the root penetration resistance, and on the other hand, it is below the destructive limit, ensuring that the overall structure of the passivation layer remains stable, and the pressure of the pulse water needle used to inject high-pressure water flow at the bottom of the planting hole is is represented as: ; wherein, is the tensile strength of the passivation layer, which represents the maximum tensile stress that the passivation layer material can withstand to maintain its structure under tensile action, and has a value range of 0.2-0.5, covering the lower limit and upper limit of the tensile strength of common mine passivation materials (such as solidified tailings soil, charcoal-binder mixture) in a dry and dense state, if less than 0.2, the passivation layer is prone to rupture during water injection, and if more than 0.5, the water needle cannot produce effective cracks, therefore this range is selected to ensure that the structure integrity and crackability are considered, is the water needle injection pressure, which is dynamically regulated to make the passivation layer produce micro-cracks but remain stable, and 0.6 is selected as a safety factor of the penetration force, which is the best balance point between achieving crack induction and structure protection, and has wide adaptability and engineering safety, 0.8 is an empirical optimal value that guarantees the crack effect while considering safety, and has a clear protection boundary control effect, ensuring that the crack is "open but not broken".

[0022] S3: Utilize the organic acids secreted by the halophytic vegetation root to induce the reorganization of the pore structure of the passivation agent, and simultaneously complex the heavy metal ions and salt ions to form a stabilized rhizosphere micro-domain; S3 specifically includes: S31: Through the microdialysis device deployed in the rhizosphere, the concentration of organic acids secreted by the plant root is obtained in real time , and a distribution function of the concentration with respect to time and space is constructed, in the model, the metabolic intensity of the plant, the secretion peak time, and the timeliness of the secretion are considered, and the inhibition effect of the proportion of mineral binder in the passivation layer on the secretion activity of the root is introduced, so that the final concentration distribution can dynamically respond to the differences in vegetation type and soil structure, and is represented as: ; wherein, is the equivalent concentration of the organic acid, For the peak time of exudation, the value of Suaeda salsa is 13-17 days after planting, which adapts to individual differences in different environments, is the time attenuation coefficient, which controls the diffusion speed of concentration distribution, and the value range is 3-5, which can balance the secretion response and attenuation speed, and ensure the time resolution accuracy of the model, is the vegetation metabolic coefficient, which reflects the influence of different plant root metabolic capacity on organic acid secretion, the value of Suaeda salsa is 0.8, and the value of Tamarix ramosissima is 0.6, because the root activity of Suaeda salsa is high and the permeability is strong, and the root of Tamarix ramosissima is thick and the permeability is weak, so the value is slightly lower, and are the mass proportion of mineral binder and the matching function respectively; S32: According to the real-time monitored organic acid concentration level , adjust the deformation degree of the pore structure of the composite passivation agent , the reorganization process takes the initial pore state as the benchmark, calculates the pore expansion ratio combined with the reaction efficiency of organic acid on biochar, and introduces the pollution load matrix as a weighting factor, so that the pollution disaster area preferentially expands the pores, thereby improving its capture capacity for pollutants, in addition, in order to prevent excessive expansion from causing structure collapse, a limiting function is introduced to constrain the upper limit of expansion, based on dynamic control of passivation agent pore deformation rate , expressed as: ; wherein, is the position time t of the diameter growth rate of the pores of the passivation agent, that is, the expansion ratio of the pores induced by the reorganization of the root system, is the initial expansion rate, which is set to 1.2, which can effectively adapt to the initial deformation capacity, and is used as the benchmark pore deformation rate without induction, is the reaction efficiency of organic acid, the value of modified biochar is 0.35, the surface carboxyl and phenolic hydroxyl groups of modified biochar enable it to react with oxalic acid, citric acid and other substances secreted by the root system, so that the pore reconstruction is more significant, therefore, it is set to 0.35, and the value of ordinary biochar is 0.15, ordinary biochar has fewer reaction sites and lower reaction rate, so it is only set to 0.15, is the organic acid concentration threshold, which is 20, which is the threshold level of active reconstruction effect of organic acid concentration in the rhizosphere, below which the pore change amplitude is small, and above which it tends to be saturated, is a hyperbolic tangent function, which is used for smoothing the response relationship and limiting the expansion rate, and the constraint condition is , 1.55 is the upper limit value of the maximum allowable expansion ratio of the passivation pore, and beyond this value, the carbon-based structure is prone to structural collapse, particle peeling or uncontrolled interconnection of pores, which seriously affects the stability and adsorption performance. Taking 1.55 times the initial expansion rate as the safety boundary can balance the reconstruction effect and structural stability, is the heavy metal pollution load matrix, 1 is the reference magnification of the structure expansion rate, indicating that under the limit condition without organic acid induction, the pore structure still maintains 100% structure size in the original state, that is , the continuity and convergence of the physical model are reserved; S33: Constructing the simultaneous fixation efficiency function of heavy metals and salt ions, including two parts, one is based on the surface area increment of biochar and the heavy metal distribution coefficient, quantifying its stabilizing effect on heavy metals, the other is considering the interference effect of salt ions on adsorption sites, and introducing the gain term of pore dynamic change rate to modify the fixation efficiency, which is expressed as: ; ; Among them, is the two-ion combination efficiency at the two-dimensional space position , indicating the ability of salt-tolerant mycorrhizal fungal hyphae to combine with calcium and magnesium ions at this position, reflecting the strength of physiological activity and environmental adaptability of the hyphae, is the heavy metal distribution coefficient, which is used to measure the distribution ability of heavy metals between solid and liquid phases. According to different soil types and heavy metal species, the value range is 10-10000, which depends on biochar type, soil pH, mineral composition and other factors, and has a direct impact on adsorption capacity. The larger the value, the stronger the adsorption capacity of heavy metals, is the specific surface area increment, which reflects the effective adsorption area of material structure pores after time evolution, with a value range of 500-1200, is the initial specific surface area, with a value range of 300-700, which depends on the type of raw material and pyrolysis conditions, and is the initial state reference of the expansion model, is the salt interference factor, which is used to characterize the inhibition effect of electrolyte on heavy metal adsorption, with a value range of 0.1-0.3, =0.1 represents weak electrolyte interference, which usually corresponds to freshwater or low-salt background soil environment, =0.3 reflects strong salt inhibition effect, which often occurs in coastal saline-alkali land, industrial wastewater infiltration zone and other areas. This range covers from mild to medium-high salt interference of common pollution scenarios, which can better express the response sensitivity of heavy metal migration process to electrolyte concentration. Choosing this range has good engineering adaptability and representativeness, is the dynamic reorganization gain coefficient, with a value range of 0.1-0.3, which is an adjustment factor for balancing the dynamic nonlinearity between the structure evolution rate and the adsorption efficiency, =0.1 reflects weak structural response, and is suitable for biochar materials with high structural stability and weak swelling dynamics, =0.3 represents a stronger structural gain effect, and is suitable for materials with high activity and high specific surface area release rate. This range can cover the dynamic response ability under various pore formation mechanisms, so that the model can be suitable for both slow-release materials and adsorption media with rapid structural reorganization. 1.5 is a non-linear enhancement index used to construct a model for amplifying the response area of cumulative pollution to rhizosphere microorganisms, which can obtain higher fitting degree and generalization ability. EC is the regional conductivity, which represents the interference of ionic strength of the solution on the charge adsorption capacity. The higher the EC, the stronger the electrostatic shielding effect, which reduces the effective adsorption rate of heavy metals, and therefore is the interference adjustment term in the denominator; S34: After the pore reorganization and ion fixation are completed, whether a stable and functional rhizosphere microdomain is formed is evaluated. The judgment is based on three indicators: whether the ion fixation efficiency reaches the set threshold, whether the pore structure reaches a sufficient expansion degree, and whether the organic acid distribution is uniform enough. Only when all the above three conditions are met, it can be considered that the region has formed an effective stabilized microenvironment, which is conducive to long-term heavy metal passivation and salt co-control, and is represented as: ; wherein, is the response intensity of heavy metals in the region, which measures the migration enhancement effect of pollutants in the biochar adsorption process. The lower limit is set to ensure that the charge response reaches the critical value of the enhanced migration and enrichment effect, and 0.85 is the balance point of charge migration efficiency and structural stability. Below this value, it may lead to insufficient retention or migration of pollutants, is the pore diameter growth rate, and 1.45 is the critical threshold of the structure capacity of biochar materials, indicating that the pore expansion reaches 45% growth compared to the initial state. Combined with the convergence characteristics and maximum constraint conditions of the function, it is the optimal midpoint of swelling intensity and structure retention, is the Laplace operator, which is used to evaluate the uniformity of root exudates distribution. This constraint is used to suppress the disturbance of rhizosphere structure caused by excessive local acid concentration. 0.1 times the reference concentration can ensure that the organic acid can maintain the activity of the microenvironment, and also prevent the formation of acid burns or excessive local enrichment, ensuring diffusion stability; S4: Introducing salt-tolerant mycorrhizal fungi to the stabilized rhizosphere microdomain, and the salt-tolerant mycorrhizal fungi and halophytic vegetation form a heavy metal barrier; S4 specifically includes: S41: Mix the salt-tolerant mycorrhizal fungal spores with suitable carrier materials to prepare the inoculum, and calculate the spore survival rate in a high-salt environment based on the difference between the salt conductivity EC and its salt tolerance threshold; at the same time, adjust the activity coefficient of the salt-tolerant mycorrhizal fungal inoculum when it is applied according to the reorganization rate of the formed pore structure, so as to enhance the micro-domain adaptability and colonization ability, and the survival rate of the salt-tolerant mycorrhizal fungal spores is expressed as: ; wherein, is the survival rate of the salt-tolerant mycorrhizal fungal spores, is the initial survival rate, indicating the upper limit of the physiological activity of the mycorrhizal spores before being affected by salt stress, and the value range is 93%-97%, which is an interval given considering the physiological differences and storage stability of the spores, is the salt attenuation coefficient, which is used to describe the inhibition sensitivity of environmental salt to the activity of mycorrhizal spores, and the fixed value is 0.12, the spore activity decreases exponentially with the change of salinity, and 0.12 is the optimal attenuation factor, is the salt tolerance threshold, which is the maximum lossless conductivity that the salt-tolerant mycorrhizal fungi can adapt to, and the fixed value is 4.0, is the pore reorganization rate, reflecting the rhizosphere micro-domain activity, and the value range is 0-0.6, reflecting the habitat quality of the rhizosphere environment to microorganisms, and the pore reorganization accelerates the gas exchange and nutrient flow, the higher the rate, the more obvious the spore survival rate improvement effect, and 0.3 is the linear enhancement coefficient of the initial survival rate to the change of the pore reorganization rate, reflecting the enhancement amplitude of the mycelium reactivity by pore disturbance, avoiding misjudgment caused by high sensitivity amplification; S42: Dynamically adjust the application amount of the salt-tolerant mycorrhizal fungal inoculum at each spatial position according to the double-ion complexing efficiency and the spatial distribution gradient of heavy metal pollution in the target area, and for the areas with low double-ion complexing efficiency or large pollution distribution gradient, increase the application amount to improve the expansion ability and form directional growth trend, and dynamically adjust the application amount of the salt-tolerant mycorrhizal fungal inoculum based on the rhizosphere micro-domain stability is expressed as: ; wherein, is the application amount of the salt-tolerant mycorrhizal fungal inoculum, is the reference application amount, indicating the amount of mycorrhizal fungal spores required per unit of soil under ideal conditions without pollution, and the fixed value is 200, which is the best balance point between ensuring the colonization efficiency and cost control, is the double-ion combination efficiency, with a value range of 0.4-1.2, the complexation efficiency affects the bioavailability of heavy metals, the higher the value, the lower the migration of heavy metals, and the less protection the mycorrhizal system needs, this factor is used to adjust the intensity of the inoculant application, 0.7 is an exponential adjustment factor for conductivity response, taking into account adaptability and robustness, 2 is the maximum multiplication coefficient of the application dose between the contaminated area and the non-contaminated area, used to control the maximum adjustable dose upper limit of the fungal agent in the contaminated area, indicating that under the influence of the spatial gradient of heavy metal pollution, the application amount in the most contaminated area can be increased to twice the baseline value, is the spatial gradient of heavy metal pollution, with an incremental application in high gradient areas, and the value range is 0-6, is the gradient response term, which is a nonlinear response function, used to amplify the effect of pollution gradient in the inoculant application strategy, this term ensures that the application amount increases rapidly in areas with severe changes in pollution, and the limit can reach , used to construct a pollution barrier "enhanced zone", 0.5 is selected as a compromise value to balance the enhancement of responsiveness (enhancing the application intensity in the pollution area) and the inhibition of aggressive fluctuations (avoiding local over-application), so as to balance the stability and sensitivity of the model; S43: The physical barrier ability of salt-tolerant mycorrhizal fungal hyphae is constructed by the hyphae density and length indicators, and the barrier effectiveness index is calculated by fusing the pore structure reorganization degree, which comprehensively reflects the synergistic effect between the salt-tolerant mycorrhizal fungal hyphae network structure and the rhizosphere microstructure, and is used to quantify the heavy metal migration inhibition ability and verify the effectiveness index of the heavy metal barrier is expressed as: ; wherein, is the effectiveness index, i.e. the rhizosphere salt-tolerant hyphae combination effect factor, representing the colonization and binding strength of the hyphae at a specific spatial point, is the salt-tolerant mycorrhizal fungal hyphae density, is the salt-tolerant mycorrhizal fungal hyphae length, is the salt-hyphae interaction coefficient, with a fixed value of 0.08, which can better balance the actual performance of salt toxicity and hyphae extension, is the pore-hyphae coupling coefficient, with a fixed value of 0.35, which can ensure that the response is not distorted but not over-enhanced, and 1.45 is the pore reorganization rate normalization threshold, which can avoid the response "saturation" triggering too early, effectively maintaining the linear growth segment of bacterial colonization contribution; S44: Three criteria are set to identify whether a barrier has been formed, one is that the barrier effectiveness index reaches the effectiveness index target value, two is that the salt-tolerant mycorrhizal fungal hyphae density exceeds the structural stability threshold, and three is that the double-ion complexation efficiency continues to grow after inoculation, indicating that the salt-tolerant mycorrhizal fungal system has long-term synergistic stability, only when all three conditions are met, can it be determined that an effective heavy metal barrier has been established, the conditions are represented as: ; wherein, is the time derivative of the efficiency of the double ion complexation, ensuring the continuous increase of the barrier, 0.90 is the effectiveness index target value, only when the mycelium binding effect reaches a higher level, it is considered that the rhizosphere zone has good microbial remediation potential, is the salt-tolerant mycorrhizal fungal mycelium density, indicates that the mycelium has reached a relatively significant distribution density in the soil, which is conducive to the development of ion buffering, ion exclusion and nutrient absorption behaviors in the rhizosphere zone, is to ensure that the conductive flux after mycelium colonization does not decrease, reflects the physiological activity tends to be stable or enhanced, and represents that the remediation potential still remains after the intervention of the bacteria.

[0023] The present application covers any substitutions, modifications, equivalent methods and solutions made on the essence and scope of the present application. In order to make the public have a thorough understanding of the present application, specific details are described in the following preferred embodiments of the present application, and the present application can also be fully understood without the description of these details for those skilled in the art. In addition, in order to avoid unnecessary confusion to the essence of the present application, well-known methods, processes, procedures, elements and circuits, etc. are not described in detail.

[0024] The above is only the preferred embodiment of the present application, it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can also be made, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for the stabilization of heavy metals in mine spoil and the simultaneous re-vegetation thereof, characterized in that, The method comprises the following steps: S1: uniformly laying a composite passivation agent on the surface layer of the mine wasteland, the composite passivation agent comprising modified biochar and a mineral binder, to form an initial passivation layer; S2: planting halophytic vegetation on the surface of the initial passivation layer, so that the root systems of the vegetation penetrate the passivation layer and extend to the contaminated substrate; S3: using organic acids secreted by the root systems of the halophytic vegetation to induce reorganization of the pore structure of the passivation agent, and simultaneously complexing heavy metal ions and separating salt ions, to form a stabilized rhizosphere microzone; S4: introducing salt-tolerant mycorrhizal fungi into the stabilized rhizosphere microzone, the salt-tolerant mycorrhizal fungi and the halophytic vegetation being symbiotic to form a heavy metal barrier.

2. The mine spoil heavy metal stabilization and revegetation synergy method according to claim 1, characterized by, The S1 comprises: S11: using a drone equipped with an XRF device to scan the area, obtaining the spatial distribution information of heavy metal concentration and soil salinity, and combining soil type correction to generate a pollution characteristic matrix; S12: according to the pollution characteristic matrix, establishing a passivation agent proportioning function, comprehensively considering the heavy metal concentration and the salt level, and dynamically determining the proportion of biochar and binder at each position; S13: inputting the proportioning result into an intelligent spreading device to perform partitioned laying as needed; S14: combining the pollution spatial gradient to adjust the laying thickness, appropriately thickening in areas with sharp changes in pollution, constructing an initial passivation layer thickness function, and calculating the initial passivation layer thickness.

3. The mine spoil heavy metal stabilization and revegetation synergy method according to claim 2, characterized by, The S13 comprises: S131: judging the pollution dominant type of each coordinate point according to the obtained composite passivation agent proportioning function value; S132: inputting the partitioned proportioning information into an intelligent spreading machine control system, automatically adjusting the material proportion according to the area type and performing differentiated laying, forming an adsorption function enhanced area in a heavy metal high concentration area, and constructing a salt resistant stable area in a salt enrichment area.

4. The mine spoil heavy metal stabilization and revegetation synergistic method according to claim 3, characterized by, The S2 comprises: S21: combining the initial passivation layer thickness, dry density and binder proportion to calculate the minimum penetration required for the root systems of the vegetation to break through the initial passivation layer; S22: comparing the minimum penetration required by the area with the inherent penetration of the root systems of the vegetation to select halophytic vegetation that can meet the requirements; S23: appropriately increasing the ultra-deep amount according to the position of the initial passivation layer and the substrate interface; S24: injecting high-pressure water flow into the planting hole to form controllable microfractures, reducing the root penetration resistance, and at the same time maintaining the stability of the passivation layer structure.

5. The mine spoil heavy metal stabilization and revegetation synergy method according to claim 4, characterized by, The S21 comprises: S211: comprehensively determining the main factors affecting the hardness of the layer according to the thickness, dry density and proportion of the mineral binder of the initial passivation layer; S212: calculating the minimum penetration required for the root systems of the vegetation to break through the initial passivation layer at each coordinate point.

6. The mine spoil heavy metal stabilization and revegetation synergistic method according to claim 4, characterized by, The S22 comprises: S221: constructing a halophytic vegetation root system inherent penetration database covering different plant species and their typical penetration ranges; S222: comparing the minimum root system penetration requirement value calculated for each area with the inherent penetration of different vegetation in the database to select candidate vegetation that can meet or exceed the requirement; S223: determining the appropriate halophytic vegetation type according to the comparison result.

7. The mine spoil heavy metal stabilization and revegetation synergy method according to claim 6, characterized by, The S3 comprises: S31: obtaining the concentration of organic acids through a rhizosphere microdialysis device, and constructing a spatiotemporal distribution model, comprehensively considering the metabolic characteristics of the vegetation, the secretion time peak and the inhibition effect of the mineral binder; S32: dynamically regulate the pore structure of the passivation agent according to the concentration change of the organic acid, combine the pollution load degree with the material reaction efficiency, control the pore expansion amplitude, and introduce a limiting function to prevent the layer from over-expanding; S33: build a composite model considering heavy metal adsorption and salt interference suppression, optimize the simultaneous fixation efficiency based on specific surface area synergy and dynamic pore response; S34: set three indicators of fixation efficiency, pore expansion, and secretion uniformity as the basis for determining whether the stabilized rhizosphere microdomain is stable.

8. The mine spoil heavy metal stabilization and revegetation synergistic method according to claim 7, characterized by, The S32 includes: S321: according to the real-time concentration level of rhizosphere organic acid, combining its reaction efficiency on biochar material, calculate the pore diameter growth rate of passivation agent, and introduce pollution load weight, preferentially make structure reorganization in serious pollution area; S322: on the basis of calculated pore expansion, use hyperbolic tangent function to nonlinearly limit the deformation amplitude.

9. The mine spoil heavy metal stabilization and revegetation synergistic method according to claim 8, characterized by, The S4 includes: S41: dynamically calculate the survival rate of mycorrhizal spores in salt-tolerant mycorrhizal fungi inoculant according to regional salt concentration and pore reorganization rate; S42: adjust the application amount of salt-tolerant mycorrhizal fungi inoculant in different areas according to the rhizosphere complexing efficiency and the spatial distribution of pollutants, guide the mycelium to expand preferentially to high-risk pollution areas; S43: comprehensive evaluation of mycelium density, length and pore structure change, whether the barrier constructed by mycelium has the ability to effectively block the migration of heavy metals; S44: when the barrier effectiveness meets the standard, the salt-tolerant mycorrhizal fungi mycelium structure is stable, and the complexing efficiency continues to increase, it is determined that an effective heavy metal barrier has been formed.

10. The mine spoil heavy metal stabilization and revegetation synergistic method according to claim 9, characterized by, The S42 includes: S421: based on the reference application amount of salt-tolerant mycorrhizal fungi inoculant, combine the current regional bi-ion complexing efficiency to carry out exponential weighted adjustment, improve the application strength of low-efficiency microdomain, and enhance the colonization potential of salt-tolerant mycorrhizal fungi mycelium; S422: according to the spatial Laplace gradient of heavy metal pollutants, introduce a gradient response function to dynamically correct the application strategy of salt-tolerant mycorrhizal fungi inoculant, and optimize the spatial expansion of salt-tolerant mycorrhizal fungi mycelium to high-risk areas.

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