Coastal wetland plant maintenance system and method

Abstract

The invention relates to the technical field of irrigation, and discloses a coastal wetland plant maintenance system and method.The method comprises the steps that firstly, concentration spatial distribution of thiosulfate and tetrathiosulfate in a root domain is obtained, the spatial position and the peak shape curvature of a concentration ratio peak are determined based on the concentration spatial distribution, and meanwhile the outer edge spatial position of a root surface iron plaque is determined; calculating position deviation and curvature deviation between the two; further measuring the root domain volume and the ion strength and sulfate radical concentration of pore water; then, a small amount of fresh water and brackish water are injected into the root domain, the spatial position of a concentration ratio peak and the change rate of curvature are observed, and the hydrochemistry and root domain reaction relation is established; according to the deviation and the change rate, the required ion strength and the sulfate radical concentration adjustment amount are solved, the volume of fresh water and the volume of brackish water required by single-time maintenance are accurately converted according to the root domain volume and the ion characteristics of different water sources, and therefore scientific regulation and control over the coastal wetland plant root domain environment are achieved.

Description

Technical Field

[0001] This invention relates to the field of irrigation technology, and more specifically, to a coastal wetland plant maintenance system and method. Background Technology

[0002] Coastal wetland soils are characterized by high salinity, frequent tidal infiltration, and significant oxygen deficiency. In this environment, iron and sulfur are highly reactive in the soil. In an aerobic environment, iron forms oxides that deposit on the surface of plant roots, creating a protective iron film; however, under anaerobic conditions, it easily transforms into soluble ferrous iron. Simultaneously, the abundant sulfate ions in the soil are reduced by microorganisms to hydrogen sulfide and other sulfides in an anaerobic environment. Plant roots, constantly growing in this dynamic environment of iron and sulfur, require the protection of the iron film while simultaneously facing the constant threat of toxicity from sulfides.

[0003] Under artificial management, coastal wetland plants are often irrigated with alternating freshwater and brackish water to conserve freshwater resources and cultivate the plants' salt tolerance. However, this irrigation method constantly alters the soil's redox state: when freshwater enters, oxygen can penetrate the soil, promoting iron oxidation and forming an iron film on the root surface; while during brackish water irrigation or when water levels drop, the soil tends towards a reducing state, promoting sulfate reduction and sulfide formation. This repeated switching causes iron deposition and dissolution, as well as sulfide formation and consumption, to fluctuate continuously.

[0004] In this constantly changing environment, the iron film should protect the roots. However, when the iron oxidation and deposition zones and the sulfide formation zones become misaligned, an accumulation zone of active substances forms on the outer surface of the root. This zone contains short-lived sulfur intermediates and free hydrogen sulfide, which can easily penetrate the protective layer and directly affect the roots, inhibiting root respiration and disrupting nutrient absorption. This leads to decreased root function, stunted growth, and even death. Summary of the Invention

[0005] This invention provides a coastal wetland plant maintenance system and method, which solves the technical problems mentioned in the background art.

[0006] In a first aspect, the present invention provides a method for the maintenance of coastal wetland plants, comprising:

[0007] S1, obtain the spatial distribution of thiosulfate and tetrathiosulfate concentrations within the root domain;

[0008] S2. Based on the spatial distribution of concentration, determine the spatial position and peak curvature of the concentration ratio peak of thiosulfate and tetrathiosulfate, and at the same time determine the spatial position of the outer edge of the root surface iron film; calculate the positional deviation between the spatial position of the concentration ratio peak and the spatial position of the outer edge of the root surface iron film, and the curvature deviation between the peak curvature of the concentration ratio peak and the reference curvature.

[0009] S3, determine the root domain volume, as well as the ionic strength and sulfate concentration of the root domain pore water;

[0010] S4. Fresh water and slightly brackish water were injected into the root zone by small perturbation, and the spatial position of the concentration ratio peak and the rate of change of peak shape curvature on the ion intensity and sulfate concentration of the root zone pore water were obtained.

[0011] S5, based on the positional deviation, curvature deviation and rate of change, the ionic strength adjustment amount and sulfate concentration adjustment amount of the root zone pore water are obtained;

[0012] S6. Based on the root zone volume, the ionic strength and sulfate concentration of the root zone pore water, as well as the ionic strength and sulfate concentration of fresh water and brackish water, the required fresh water volume and brackish water volume for a single maintenance cycle are calculated.

[0013] Furthermore, based on the spatial distribution of concentrations, the spatial location and peak curvature of the concentration ratio peak of thiosulfate and tetrathiosulfate were determined, including:

[0014] Coordinate points set along the radial direction of the target plant's rhizosphere at preset radial step intervals;

[0015] The concentration values ​​of thiosulfate and tetrathiosulfate were measured at each coordinate point to form thiosulfate concentration sequences and tetrathiosulfate concentration sequences.

[0016] Divide the tetrathiosulfate concentration value at each coordinate point by the thiosulfate concentration value to obtain the concentration ratio at the coordinate point, and arrange the coordinate points in order to form a concentration ratio curve.

[0017] The point with the largest concentration ratio in the concentration ratio curve is taken as the concentration ratio peak, and the coordinates corresponding to the concentration ratio peak are taken as the spatial location of the concentration ratio peak.

[0018] Using the spatial location of the concentration ratio peak as the center, three adjacent coordinate points are selected to form a three-point neighborhood; the peak curvature of the concentration ratio peak is calculated using the second-order difference method based on the concentration ratio of the three-point neighborhood.

[0019] Furthermore, determining the spatial location of the outer edge of the root surface iron film includes:

[0020] At each coordinate point, the dissolved oxygen concentration and ferric iron indicator signal values ​​were measured to generate dissolved oxygen concentration sequences and ferric iron indicator signal sequences, respectively.

[0021] The dissolved oxygen concentration sequence and the ferric iron indicator signal sequence were smoothed by the moving average method to obtain the smoothed dissolved oxygen concentration sequence and the smoothed ferric iron indicator signal sequence, respectively.

[0022] In the smoothed ferric iron indicator signal sequence, the point with the largest smoothed ferric iron indicator signal is taken as the smoothed ferric iron indicator signal peak; the coordinates corresponding to the smoothed ferric iron indicator signal peak are taken as the peak coordinates of the smoothed ferric iron indicator signal peak.

[0023] The smoothed ferric iron indicator signal at the Nth coordinate point in the smoothed ferric iron indicator signal sequence is taken as the baseline value of the ferric iron signal; where N represents the number of coordinate points.

[0024] Take half of the difference between the peak value of the smoothed ferric iron indicator signal and the baseline value, and sum it with the baseline value to obtain the half-peak value;

[0025] The smoothed ferric iron indicator signal sequence is searched radially outward from the first coordinate point. After the peak coordinate, the smoothed ferric iron signal value first drops to half the peak value and crosses two adjacent coordinate points of the half peak value. The spatial position of the outer edge of the root surface iron film is calculated by linear interpolation in the region between the two coordinate points.

[0026] Furthermore, the spatial deviation between the concentration ratio peak and the outer edge of the root surface iron film is calculated, as well as the curvature deviation between the peak shape curvature of the concentration ratio peak and the reference curvature, including:

[0027] Subtracting the spatial position of the outer edge of the root surface iron film from the spatial position of the concentration ratio peak yields the positional deviation between the spatial position of the concentration ratio peak and the spatial position of the outer edge of the root surface iron film.

[0028] Subtracting the peak curvature of the concentration ratio peak from the reference curvature yields the curvature deviation between the peak curvature of the concentration ratio peak and the reference curvature.

[0029] Furthermore, by injecting freshwater and brackish water into the root zone with small agitations, the spatial location of the concentration ratio peak and the rate of change of peak shape curvature with respect to the ionic strength and sulfate concentration in the root zone pore water were obtained, including:

[0030] Set the perturbation volume for freshwater and brackish water; where both the perturbation volume for freshwater and brackish water are positive values ​​and do not exceed five percent of the root domain volume;

[0031] During freshwater and brackish water perturbation processes, the ambient temperature of the root zone was kept constant.

[0032] The freshwater perturbation process is as follows:

[0033] A volume of freshwater with a perturbation was injected into the root domain. After the freshwater and the pore water in the root domain were mixed for a first preset time, the first spatial position and the first peak curvature of the concentration ratio peak were remeasured.

[0034] Calculate the first position increment; where the first position increment is the first spatial position of the concentration ratio peak minus the spatial position of the concentration ratio peak;

[0035] Calculate the first curvature increment; where the first curvature increment is the first peak shape curvature of the concentration ratio peak minus the peak shape curvature of the concentration ratio peak;

[0036] The increments of the first ionic strength and the first sulfate concentration are calculated based on the principle of conservation of mixtures, as follows:

[0037] The first ion intensity increment is obtained by multiplying the difference between the ion intensity of freshwater and the ion intensity of root domain pore water at the current moment by the freshwater perturbation volume and then dividing the product by the root domain volume.

[0038] The first sulfate concentration increment is obtained by multiplying the difference between the sulfate concentration of freshwater and the sulfate concentration of root zone pore water at the current moment by the freshwater perturbation volume and then dividing the product by the root zone volume.

[0039] Wait for the preset recovery time;

[0040] Inject a slightly perturbed volume of slightly saline water into the root zone. After the slightly saline water mixes with the pore water in the root zone for a second preset time, remeasure the second spatial position and second peak curvature of the concentration ratio peak.

[0041] Calculate the second position increment; where the second position increment is the second spatial position of the concentration ratio peak minus the spatial position of the concentration ratio peak;

[0042] Calculate the second curvature increment; where the second curvature increment is the second peak curvature of the concentration ratio peak minus the peak curvature of the concentration ratio peak;

[0043] The increments of the second ionic strength and the second sulfate concentration are calculated based on the principle of conservation of mixing, as follows:

[0044] The second ion intensity increment is obtained by multiplying the difference between the ion intensity of the brackish water and the ion intensity of the root domain pore water at the current moment by the product of the brackish water perturbation volume and the root domain volume.

[0045] The second sulfate concentration increment is obtained by multiplying the difference between the sulfate concentration in the brackish water and the sulfate concentration in the root zone pore water at the current moment by the product of the brackish water perturbation volume and the root zone volume.

[0046] The rate of change is calculated as follows:

[0047]

[0048]

[0049]

[0050]

[0051] in, Indicates the increment at the first position. Indicates the increment at the second position. Indicates the first curvature increment. This represents the second curvature increment. Indicates the first ionic strength increment. This indicates the second ionic strength increment. This indicates the increase in the first sulfate concentration. This indicates the increase in the concentration of the second sulfate ion. This represents the rate of change of the spatial position of the concentration ratio peak with respect to the ionic intensity of the root domain pore water. This indicates the rate of change of the spatial location of the concentration ratio peak with respect to the sulfate concentration in the root zone pore water. This represents the rate of change in the peak shape curvature of the concentration ratio peak with respect to the ionic intensity of the root zone pore water. This represents the rate of change of the peak shape curvature of the concentration ratio peak with respect to the sulfate concentration in the root zone pore water.

[0052] Furthermore, based on the positional deviation, curvature deviation, and rate of change, the ionic strength adjustment and sulfate concentration adjustment of the root zone pore water are calculated, including:

[0053] Define the target spatial position change of the concentration ratio peak; where the target spatial position change is the negative of the position deviation.

[0054] Define the target peak curvature change for the concentration ratio peak; where the target peak curvature change is the curvature deviation.

[0055] The first linear equation is established by relating the spatial position of the concentration ratio peak to the rate of change of ionic intensity in root zone pore water and the spatial position of the concentration ratio peak to the rate of change of sulfate concentration in root zone pore water, as follows:

[0056]

[0057] A second linear equation is established using the rate of change of the peak shape curvature of the concentration ratio peak with respect to the change of the ionic intensity of the root zone pore water and the rate of change of the peak shape curvature of the concentration ratio peak with respect to the change of the sulfate concentration of the root zone pore water, as follows:

[0058]

[0059] in, This represents the adjustment amount of ionic strength for the root domain pore water to be solved. The amount of sulfate concentration adjustment to be determined in the root zone pore water. Indicates positional deviation. Indicates curvature deviation;

[0060] If satisfied If the first and second linear equations are combined, the ionic strength adjustment and sulfate concentration adjustment of the root domain pore water can be calculated; otherwise, return to S1.

[0061] Furthermore, based on the root zone volume, the current ionic strength and sulfate concentration of the root zone pore water, as well as the ionic strength and sulfate concentration of freshwater and brackish water, the required freshwater and brackish water volumes for a single maintenance cycle are calculated, including:

[0062] Based on the principle of mass conservation, the ionic strength equation and sulfate concentration equation are established as follows:

[0063] Ionic strength equation: ;

[0064] Sulfate concentration equation: ;

[0065] in, , and These represent the ionic strengths of freshwater, brackish water, and rhizosphere pore water, respectively. , and These represent the sulfate concentrations in freshwater, brackish water, and rhizosphere pore water, respectively. Represents the volume of the root region. and These represent the adjustment amounts for ionic strength and sulfate concentration in root zone pore water, respectively. and Represents the volume of freshwater and brackish water required for a single maintenance cycle;

[0066] like If the ionic strength equation and sulfate concentration equation are combined, the required freshwater volume and brackish water volume for a single maintenance cycle can be calculated; otherwise, return to S1.

[0067] Furthermore, apply the required volume of fresh water and the required volume of brackish water for each maintenance cycle, in the order of fresh water first and then brackish water.

[0068] Secondly, a coastal wetland vegetation conservation system, realizing the coastal wetland vegetation conservation system as described in any one of the claims, comprising:

[0069] The sulfur concentration distribution module is used to obtain the spatial distribution of thiosulfate and tetrathiosulfate concentrations within the root zone.

[0070] The deviation calculation module is used to determine the spatial position and peak curvature of the concentration ratio peak of thiosulfate and tetrathiosulfate based on the spatial distribution of concentration, and at the same time determine the spatial position of the outer edge of the root surface iron film; calculate the positional deviation between the spatial position of the concentration ratio peak and the spatial position of the outer edge of the root surface iron film, and the curvature deviation between the peak curvature of the concentration ratio peak and the reference curvature.

[0071] The data acquisition module is used to determine the root zone volume, as well as the ionic strength and sulfate concentration of the root zone pore water.

[0072] The perturbation response module is used to inject fresh water and brackish water into the root zone through small perturbations, and obtain the spatial position of the concentration ratio peak and the rate of change of the peak shape curvature with the ion intensity and sulfate concentration of the root zone pore water.

[0073] The water chemistry adjustment calculation module is used to calculate the ionic strength adjustment and sulfate concentration adjustment of the root zone pore water based on the position deviation, curvature deviation and rate of change.

[0074] The alternating water consumption calculation module is used to calculate the volume of fresh water and brackish water required for a single maintenance cycle based on the root zone volume, the ionic strength and sulfate concentration of the root zone pore water, as well as the ionic strength and sulfate concentration of fresh water and brackish water.

[0075] The beneficial effects of this invention are as follows: By accurately monitoring and analyzing the spatial distribution of thiosulfate, tetrathiosulfate, and iron film on the root surface within the plant rhizosphere, and combining this with the disturbance response to alternating injections of fresh and slightly brackish water, the ionic strength and sulfate concentration of the pore water in the rhizosphere can be dynamically calculated and scientifically adjusted. This effectively avoids the toxic effects caused by the misalignment of the iron film protective layer and the sulfide formation zone. This invention not only significantly improves the stability and stress resistance of plant roots in high-salt, hypoxic, and tidal environments, but also conserves freshwater resources while ensuring healthy plant growth, achieving precision and efficiency in the maintenance process. Attached Figure Description

[0076] Figure 1 This is a flowchart of a coastal wetland plant maintenance method according to the present invention;

[0077] Figure 2 This is a block diagram of a coastal wetland plant maintenance system according to the present invention. Detailed Implementation

[0078] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, features described in some examples may be combined in other examples.

[0079] Example 1

[0080] like Figure 1 As shown, a method for the maintenance of coastal wetland plants includes:

[0081] S1, obtain the spatial distribution of thiosulfate and tetrathiosulfate concentrations within the root domain;

[0082] S2. Based on the spatial distribution of concentration, determine the spatial position and peak curvature of the concentration ratio peak of thiosulfate and tetrathiosulfate, and at the same time determine the spatial position of the outer edge of the root surface iron film; calculate the positional deviation between the spatial position of the concentration ratio peak and the spatial position of the outer edge of the root surface iron film, and the curvature deviation between the peak curvature of the concentration ratio peak and the reference curvature.

[0083] S3, determine the root domain volume, as well as the ionic strength and sulfate concentration of the root domain pore water;

[0084] S4. Fresh water and slightly brackish water were injected into the root zone by small perturbation, and the spatial position of the concentration ratio peak and the rate of change of peak shape curvature on the ion intensity and sulfate concentration of the root zone pore water were obtained.

[0085] S5, based on the positional deviation, curvature deviation and rate of change, the ionic strength adjustment amount and sulfate concentration adjustment amount of the root zone pore water are obtained;

[0086] S6. Based on the root zone volume, the ionic strength and sulfate concentration of the root zone pore water, as well as the ionic strength and sulfate concentration of fresh water and brackish water, the required fresh water volume and brackish water volume for a single maintenance cycle are calculated.

[0087] It should be noted that the root zone refers to the soil area where plant roots grow, distribute, and exchange substances with the surrounding environment. It is the space where roots and soil interact, and the root zone is determined by experts.

[0088] It should be noted that rhizosphere pore water refers to the water present in the soil pores within the rhizosphere, which is the liquid portion filling the gaps between soil particles. Rhizosphere pore water contains a variety of dissolved ions, and its ionic composition and concentration reflect the chemical environment of the rhizosphere.

[0089] It should be noted that the root surface iron film is an iron oxide deposit layer that forms on the surface of plant roots, and its formation is closely related to the oxidative environment of the root zone. In coastal wetland environments, when aerobic conditions exist in the root zone, iron is oxidized in the form of ferric iron and deposited on the surface of plant roots, forming a protective film-like structure that can act as a barrier to reduce the damage of toxic substances such as sulfides to the roots.

[0090] In one embodiment of the present invention, determining the spatial position and peak curvature of the concentration ratio peak of thiosulfate and tetrathiosulfate based on the spatial distribution of concentration includes:

[0091] Coordinate points set along the radial direction of the target plant's rhizosphere at preset radial step intervals;

[0092] In detail, coordinate points are set along the radial direction of the target plant rhizosphere at preset radial step intervals, thereby determining the measurement positions at preset fixed distance intervals in the radial direction from the root surface outward around the plant root system, so as to achieve systematic coverage of the root zone space.

[0093] Taking reeds, a common species in coastal wetlands, as an example, the coordinate points are set along the radial direction of their rhizosphere as follows:

[0094] Select the main root of the reed (about 2-3 mm in diameter), take the root surface as the starting point (defined as the origin of the radial coordinate, i.e., position 0), and proceed in a radial direction away from the root surface (such as the horizontal direction outward from the soil), with a preset radial step size of 0.5 mm.

[0095] Starting from the root table, set the coordinate points sequentially:

[0096] The first coordinate point is located at the root table, with coordinates of 0 mm;

[0097] The second coordinate point is 0.5 mm away from the root table, and its coordinates are 0.5 mm.

[0098] The third coordinate point is 1.0 mm away from the root table, and its coordinates are 1.0 mm.

[0099] The fourth coordinate point is 1.5 mm away from the root table, and its coordinates are 1.5 mm.

[0100] This process continues until the coordinate points extend to a distance of 5.0 mm from the root surface (a total of 11 coordinate points, covering the main areas of thiosulfate and tetrathiosulfate concentration changes within the root domain).

[0101] The concentration values ​​of thiosulfate and tetrathiosulfate were measured at each coordinate point to form thiosulfate concentration sequences and tetrathiosulfate concentration sequences.

[0102] In detail, the concentrations of thiosulfate and tetrathiosulfate were measured at each coordinate point and a concentration sequence was formed because these two sulfur forms are intermediate products of the sulfide redox process in the rhizosphere, and their concentration changes reflect the dynamics of the rhizosphere chemical environment. Arranging the concentrations at each point in coordinate order as a sequence clearly shows the distribution pattern of the two substances in the radial direction of the rhizosphere.

[0103] Divide the tetrathiosulfate concentration value at each coordinate point by the thiosulfate concentration value to obtain the concentration ratio at the coordinate point, and arrange the coordinate points in order to form a concentration ratio curve.

[0104] In detail, the concentration ratio of tetrathiosulfate to thiosulfate is calculated for each coordinate point, and a ratio curve is generated. This eliminates the interference of fluctuations in the absolute value of a single concentration through the relative proportion, reflecting the equilibrium state of the conversion between the two sulfur forms. The ratio curve can show the spatial trend of this equilibrium state.

[0105] The point with the largest concentration ratio in the concentration ratio curve is taken as the concentration ratio peak, and the coordinates corresponding to the concentration ratio peak are taken as the spatial location of the concentration ratio peak.

[0106] In detail, the point with the largest ratio in the concentration ratio curve is defined as the concentration ratio peak, and its corresponding coordinates are its spatial location. This is because this peak point is where the ratio of the two sulfur forms is most significant, corresponding to a specific redox interface in the root zone. The spatial relationship between this location and the iron film on the root surface is directly related to the risk of sulfide toxicity to plant roots.

[0107] Using the spatial location of the concentration ratio peak as the center, three adjacent coordinate points are selected to form a three-point neighborhood; the peak curvature of the concentration ratio peak is calculated using the second-order difference method based on the concentration ratio of the three-point neighborhood.

[0108] In detail, a three-point neighborhood is formed by selecting three adjacent coordinate points centered on the spatial location of the concentration ratio peak. This is because these three points can collectively reflect the concentration change trend near the peak. The second-order difference method is used to calculate the peak curvature using the concentration ratios at these three points, as this method quantifies the degree of curvature of the quantification curve. Peak curvature reflects the steepness of the ratio peak; a larger curvature indicates more drastic concentration changes near the peak, corresponding to a more significant gradient in the local chemical environment of the root domain; a smaller curvature indicates a smoother peak transition, suggesting a relatively stable root domain environment.

[0109] In one embodiment of the present invention, determining the spatial position of the outer edge of the root surface iron film includes:

[0110] At each coordinate point, the dissolved oxygen concentration and ferric iron indicator signal values ​​were measured to generate dissolved oxygen concentration sequences and ferric iron indicator signal sequences, respectively.

[0111] In detail, the dissolved oxygen concentration and ferric iron (Fe3+) indicator signal values ​​were measured and sequenced at each coordinate point because the formation of the root surface iron film is directly related to the rhizosphere oxidative environment. The dissolved oxygen concentration reflects the radial redox gradient in the rhizosphere, the iron film is mainly composed of ferric oxides, and the ferric iron indicator signal is related to the distribution of the iron film.

[0112] The dissolved oxygen concentration sequence and the ferric iron indicator signal sequence were smoothed by the moving average method to obtain the smoothed dissolved oxygen concentration sequence and the smoothed ferric iron indicator signal sequence, respectively.

[0113] In detail, the dissolved oxygen concentration sequence and the ferric iron indicator signal sequence were smoothed using a moving average method to eliminate random errors or fluctuations that may exist during the measurement process. The original measurement data may be noisy due to instantaneous changes in the local microenvironment. Smoothing can highlight the overall trend of the data, make the distribution characteristics of the iron film-related signals clearer, and avoid misjudgment of peaks caused by accidental fluctuations.

[0114] In the smoothed ferric iron indicator signal sequence, the point with the largest smoothed ferric iron indicator signal is taken as the smoothed ferric iron indicator signal peak; the coordinates corresponding to the smoothed ferric iron indicator signal peak are taken as the peak coordinates of the smoothed ferric iron indicator signal peak.

[0115] In detail, determining the peak and peak coordinates of the smoothed ferric iron (Fe3O4) indicator signal in the smoothed Fe3O4 indicator signal sequence is crucial because the iron film is an enriched region of ferric oxide, and its corresponding Fe3O4 indicator signal will be significantly higher than the surrounding area. The location of the signal peak is the core region where the iron film is most densely packed, and it is a key reference point for defining the extent of the iron film.

[0116] The smoothed ferric iron indicator signal at the Nth coordinate point in the smoothed ferric iron indicator signal sequence is taken as the baseline value of the ferric iron signal; where N represents the number of coordinate points.

[0117] In detail, the signal at the Nth coordinate point in the smoothed ferric iron indicator signal sequence is taken as the baseline value of the ferric iron signal because the Nth coordinate point is the outermost measurement point along the radial direction, far away from the influence range of the root system, and is least affected by the direct effect of the iron film on the root surface. Its signal can represent the background signal level of the iron film-free area outside the root domain.

[0118] Take half of the difference between the peak value of the smoothed ferric iron indicator signal and the baseline value, and sum it with the baseline value to obtain the half-peak value;

[0119] In detail, the half-peak value is calculated to quantify the critical signal value at which the iron film transitions from the core region to the background region. The half-peak value is calculated as half the difference between the peak value and the baseline value plus the baseline value, which not only reflects the significant characteristics of the iron film signal but also effectively distinguishes the iron film region from the background region.

[0120] The smoothed ferric iron indicator signal sequence is searched radially outward from the first coordinate point. After the peak coordinate, the smoothed ferric iron signal value first drops to half the peak value and crosses two adjacent coordinate points of the half peak value. The spatial position of the outer edge of the root surface iron film is calculated by linear interpolation in the region between the two coordinate points.

[0121] In detail, the search proceeds radially outward from the first coordinate point. After the peak coordinates, it identifies two adjacent coordinate points where the smoothed ferric iron signal first drops to half-peak value and crosses it. Linear interpolation is then used to calculate the spatial position of the outer edge of the iron film. This is because the outer edge of the iron film is not an abrupt boundary, but rather a gradual transition region where the signal gradually decreases from above half-peak value to below half-peak value. The two adjacent points are located on opposite sides of this transition region. Linear interpolation, based on the signal change trend at these two points, calculates the position where the signal just reaches half-peak value. This position represents the spatial coordinates of the outer edge of the iron film, thus locating its boundary.

[0122] In one embodiment of the present invention, calculating the positional deviation between the spatial position of the concentration ratio peak and the outer edge of the root surface iron film, and the curvature deviation between the peak curvature of the concentration ratio peak and the reference curvature, includes:

[0123] Subtracting the spatial position of the outer edge of the root surface iron film from the spatial position of the concentration ratio peak yields the positional deviation between the spatial position of the concentration ratio peak and the spatial position of the outer edge of the root surface iron film.

[0124] In detail, the spatial deviation between the concentration ratio peak and the outer edge of the root surface iron film is calculated, thereby quantifying the relative positional relationship through the difference in their spatial coordinates. The spatial position of the concentration ratio peak corresponds to the interface between thiosulfate and tetrathiosulfate, and the position of this interface is related to the distribution of sulfide active regions in the root zone. The outer edge of the root surface iron film is the boundary of the physicochemical barrier protecting the roots. Subtracting the latter from the former yields the positional deviation, which reflects the degree of spatial misalignment between the two interfaces: a positive deviation indicates that the concentration ratio peak is located outside the outer edge of the iron film, meaning that the sulfide active regions may have breached the protective range of the iron film, increasing the risk of root poisoning; a negative deviation indicates that the concentration ratio peak is located inside the outer edge of the iron film, which may interfere with the normal formation and function of the iron film.

[0125] Subtracting the peak curvature of the concentration ratio peak from the reference curvature yields the curvature deviation between the peak curvature of the concentration ratio peak and the reference curvature.

[0126] In detail, the curvature deviation of the concentration ratio peak is calculated by comparing its peak curvature with that of a reference curvature. This difference quantifies the degree of deviation in peak shape. The reference curvature represents the steepness of the peak shape that the concentration ratio peak should possess under ideal conditions in the rhizosphere environment. Ideally, a steep peak shape (larger curvature) means that the conversion between thiosulfate and tetrathiosulfate is completed within a narrow space, resulting in a clear gradient in the rhizosphere chemical environment and higher regulation efficiency. Peak curvature, on the other hand, reflects the shape of the ratio peak in actual measurements. The curvature deviation obtained by subtracting the peak curvature from the reference curvature reflects the difference between the actual peak shape and the ideal state: a positive deviation indicates that the actual peak shape is gentler than the ideal state, suggesting that the conversion region between thiosulfate and tetrathiosulfate has diffused, leading to decreased stability of the rhizosphere chemical environment; a negative deviation indicates that the actual peak shape is steeper than the ideal state, potentially indicating local overreaction, which is also detrimental to the balance of the rhizosphere environment.

[0127] It should be noted that the reference curvature is obtained as follows:

[0128] In the root zones of healthy plants of the same species as the target plants and growing in similar coastal wetland environments (with consistent soil salinity, tidal characteristics, and oxygen deficiency), the peak curvature of the concentration ratio peak of thiosulfate to tetrathiosulfate was measured using a method for determining the peak curvature of the concentration ratio peak, and a reference curvature was obtained. The healthy plant root zones were determined by experts.

[0129] In one embodiment of the present invention, fresh water and slightly brackish water are injected into the root zone through a small-amplitude perturbation method, and the spatial position and peak curvature of the concentration ratio peak are obtained as a function of the changes in the ion intensity and sulfate concentration of the root zone pore water, including:

[0130] Set the perturbation volume for freshwater and brackish water; where both the perturbation volume for freshwater and brackish water are positive values ​​and do not exceed five percent of the root domain volume;

[0131] In detail, the perturbation volumes for freshwater and brackish water are set, both of which are positive and do not exceed 5% of the root zone volume, thereby controlling the perturbation amplitude through small-dose injection. Small perturbations can avoid drastic changes in the original chemical environment of the root zone, ensuring that the position and curvature changes of the concentration ratio peak are caused only by the difference in ionic strength and sulfate concentration of the injected water, and that the changes are within the linear response range.

[0132] During freshwater and brackish water perturbation processes, the ambient temperature of the root zone was kept constant.

[0133] In detail, maintaining a constant rhizosphere temperature during freshwater and brackish water perturbations is to eliminate the interference of temperature on chemical reactions within the rhizosphere. Temperature variations can affect the conversion rate of thiosulfate to tetrathiosulfate, the formation and dissolution of iron films, and microbial activity, thereby altering the concentration ratio peak. Maintaining a constant temperature ensures that the measured position and curvature changes are only related to ionic strength and sulfate concentration, guaranteeing the singularity of variables.

[0134] The freshwater perturbation process is as follows:

[0135] A volume of freshwater with a perturbation was injected into the root domain. After the freshwater and the pore water in the root domain were mixed for a first preset time, the first spatial position and the first peak curvature of the concentration ratio peak were remeasured.

[0136] Calculate the first position increment; where the first position increment is the first spatial position of the concentration ratio peak minus the spatial position of the concentration ratio peak;

[0137] Calculate the first curvature increment; where the first curvature increment is the first peak shape curvature of the concentration ratio peak minus the peak shape curvature of the concentration ratio peak;

[0138] In detail, during the freshwater perturbation process, after injecting a perturbation volume of freshwater into the root zone, a first preset time is allowed for the freshwater to fully mix with the pore water in the root zone, ensuring a uniform distribution of ionic strength and sulfate concentration within the root zone. The measured first spatial position and first peak curvature at this time accurately reflect the stable state under the perturbation. Calculating the first position increment and the first curvature increment is to quantify the specific magnitude of changes in the spatial position and shape of the concentration ratio peak caused by the freshwater perturbation.

[0139] The increments of the first ionic strength and the first sulfate concentration are calculated based on the principle of conservation of mixtures, as follows:

[0140] The first ion intensity increment is obtained by multiplying the difference between the ion intensity of freshwater and the ion intensity of root domain pore water at the current moment by the freshwater perturbation volume and then dividing the product by the root domain volume.

[0141] The first sulfate concentration increment is obtained by multiplying the difference between the sulfate concentration of freshwater and the sulfate concentration of root zone pore water at the current moment by the freshwater perturbation volume and then dividing the product by the root zone volume.

[0142] In detail, the first increase in ionic strength and the first increase in sulfate concentration are calculated based on the principle of conservation of mixing, which is based on the conservation of solute mass. After the freshwater and the root zone pore water are mixed, the total amount of ions and sulfate is equal to the sum of the total amounts of the two before mixing. By using the difference in ionic strength and sulfate concentration between the freshwater and the current root zone pore water, combined with the ratio of the freshwater perturbation volume to the root zone volume, the concentration increase caused by the perturbation can be calculated, thus quantifying the magnitude of the perturbation.

[0143] Wait for the preset recovery time;

[0144] In detail, the preset recovery time is to allow the root domain environment to recover to a stable state after freshwater disturbance, eliminate the continued impact of the previous disturbance, ensure that the measurement results of subsequent brackish water disturbance are independent and reliable, and avoid mutual interference between the two disturbances.

[0145] Inject a slightly perturbed volume of slightly saline water into the root zone. After the slightly saline water mixes with the pore water in the root zone for a second preset time, remeasure the second spatial position and second peak curvature of the concentration ratio peak.

[0146] Calculate the second position increment; where the second position increment is the second spatial position of the concentration ratio peak minus the spatial position of the concentration ratio peak;

[0147] Calculate the second curvature increment; where the second curvature increment is the second peak curvature of the concentration ratio peak minus the peak curvature of the concentration ratio peak;

[0148] The increments of the second ionic strength and the second sulfate concentration are calculated based on the principle of conservation of mixing, as follows:

[0149] The second ion intensity increment is obtained by multiplying the difference between the ion intensity of the brackish water and the ion intensity of the root domain pore water at the current moment by the product of the brackish water perturbation volume and the root domain volume.

[0150] The second sulfate concentration increment is obtained by multiplying the difference between the sulfate concentration in the brackish water and the sulfate concentration in the root zone pore water at the current moment by the product of the brackish water perturbation volume and the root zone volume.

[0151] In detail, after injecting a slightly perturbed volume of brackish water, a second preset time is allowed to be waited for uniform mixing. The second spatial position and the second peak curvature are then measured, and the increments of the second position and curvature are calculated to quantify the impact of the brackish water perturbation on the concentration ratio peak. Based on the principle of mixing conservation, the increments of the second ionic strength and the second sulfate concentration are calculated, again quantifying the concentration change caused by the brackish water perturbation through the concentration difference and the ratio of the perturbation volume to the root domain volume.

[0152] The rate of change is calculated as follows:

[0153]

[0154]

[0155]

[0156]

[0157] in, Indicates the increment at the first position. Indicates the increment at the second position. Indicates the first curvature increment. This represents the second curvature increment. Indicates the first ionic strength increment. This indicates the second ionic strength increment. This indicates the increase in the first sulfate concentration. This indicates the increase in the concentration of the second sulfate ion. This represents the rate of change of the spatial position of the concentration ratio peak with respect to the ionic intensity of the root domain pore water. This indicates the rate of change of the spatial location of the concentration ratio peak with respect to the sulfate concentration in the root zone pore water. This represents the rate of change in the peak shape curvature of the concentration ratio peak with respect to the ionic intensity of the root zone pore water. This represents the rate of change of the peak shape curvature of the concentration ratio peak with respect to the sulfate concentration in the root zone pore water.

[0158] In detail, using incremental data generated from two perturbations (freshwater and brackish water), a linear response relationship was established between the characteristics (position and curvature) of the concentration ratio peak and the parameters (ionic strength and sulfate concentration) of the root zone pore water. The numerator and denominator of the formula are derived by solving a system of two linear equations based on the combination of position increments, curvature increments, ionic strength increments, and sulfate concentration increments from the two perturbations. This quantifies the influence of unit changes in ionic strength or sulfate concentration on the position and curvature of the concentration ratio peak.

[0159] In one embodiment of the present invention, the ionic strength adjustment and sulfate concentration adjustment of the root zone pore water are calculated based on the positional deviation, curvature deviation, and rate of change, including:

[0160] Define the target spatial position change of the concentration ratio peak; where the target spatial position change is the negative of the position deviation.

[0161] In detail, the target spatial position change of the concentration ratio peak is set as the negative of the positional deviation, thus clearly defining the spatial correction target to be achieved through adjustment. The positional deviation reflects the actual degree of misalignment between the concentration ratio peak and the outer edge of the root surface iron film. Its negative value represents the distance and direction in which the concentration ratio peak needs to be moved to compensate for the misalignment. If the positional deviation is positive, it indicates that the ratio peak is outside the outer edge of the iron film, and the target change is negative, meaning the ratio peak needs to be moved inward by a corresponding distance; if the positional deviation is negative, the target change is positive, meaning the ratio peak needs to be moved outward, ultimately aligning the two spatially.

[0162] Define the target peak curvature change for the concentration ratio peak; where the target peak curvature change is the curvature deviation.

[0163] In detail, the target change in peak curvature for the concentration ratio peak is defined as curvature deviation, thus clarifying the morphology correction target. Curvature deviation reflects the difference between the actual peak curvature and the reference curvature. Using it as the target change means that adjustments need to be made to bring the actual peak curvature to the reference curvature level. If the curvature deviation is positive, it indicates that the actual peak shape is flatter, and the goal is to increase the curvature to make the peak shape steeper; if the curvature deviation is negative, it indicates that the actual peak shape is steeper, and the goal is to decrease the curvature to make the peak shape flatter, ultimately making the peak shape conform to the ideal state.

[0164] The first linear equation is established by relating the spatial position of the concentration ratio peak to the rate of change of ionic intensity in root zone pore water and the spatial position of the concentration ratio peak to the rate of change of sulfate concentration in root zone pore water, as follows:

[0165]

[0166] In detail, the first linear equation is established because the spatial position change of the concentration ratio peak is caused by the combined effects of ionic strength adjustment and sulfate concentration adjustment. On the left side of the equation, the ionic strength adjustment is multiplied by the rate of change of position with respect to ionic strength, reflecting the effect of ionic strength change on position; the sulfate concentration adjustment is multiplied by the rate of change of position with respect to sulfate concentration, reflecting the effect of sulfate concentration change on position; the sum of the two is the total position change, which must be equal to the target spatial position change (the negative of the position deviation), thus constraining the combination relationship of the two adjustment amounts through the equation.

[0167] A second linear equation is established using the rate of change of the peak shape curvature of the concentration ratio peak with respect to the change of the ionic intensity of the root zone pore water and the rate of change of the peak shape curvature of the concentration ratio peak with respect to the change of the sulfate concentration of the root zone pore water, as follows:

[0168]

[0169] In detail, a second linear equation is established to address changes in peak curvature. On the left side of the equation, the ion strength adjustment is multiplied by the rate of change of curvature with respect to ion strength, reflecting the effect of changes in ion strength on curvature; the sulfate concentration adjustment is multiplied by the rate of change of curvature with respect to sulfate concentration, reflecting the effect of changes in sulfate concentration on curvature; the sum of the two is the total curvature change, which must equal the target peak curvature change (curvature deviation), further constraining the combination relationship between the two adjustment amounts.

[0170] in, This represents the adjustment amount of ionic strength for the root domain pore water to be solved. The amount of sulfate concentration adjustment to be determined in the root zone pore water. Indicates positional deviation. Indicates curvature deviation;

[0171] If satisfied If the first and second linear equations are combined, the ionic strength adjustment and sulfate concentration adjustment of the root domain pore water can be calculated; otherwise, return to S1.

[0172] Detailed requirements must be met. This is to ensure that the above system of two linear equations has a unique solution. This formula is the determinant of the coefficients of the system of equations. If the determinant is not 0, it indicates that the effects of ionic strength and sulfate concentration on position and curvature are independent and there is no linear correlation. The adjustment amount can be uniquely determined by solving the simultaneous equations. If the determinant is 0, it indicates that the effects of the two adjustments on position and curvature are linearly dependent and cannot be uniquely solved because there is an error in the data. Therefore, it is necessary to return to S1 to obtain the concentration distribution again.

[0173] In one embodiment of the present invention, the required volume of freshwater and brackish water for a single maintenance cycle is calculated based on the root zone volume, the ionic strength and sulfate concentration of the current root zone pore water, and the ionic strength and sulfate concentration of freshwater and brackish water, including:

[0174] Based on the principle of mass conservation, the ionic strength equation and sulfate concentration equation are established as follows:

[0175] The principle of mass conservation: The ionic strength and total amount of sulfate carried by the injected fresh water and brackish water must be exactly enough to replenish the pore water in the root zone to achieve the target adjustment amount, ensuring that the total amount of ions and sulfate in the root zone is balanced before and after adjustment.

[0176] Ionic strength equation: ;

[0177] In the ionic strength equation, the two terms on the left-hand side correspond to the increases in ionic strength resulting from the injection of freshwater and brackish water, respectively. and The difference is the difference in ionic strength between freshwater and the original pore water in the root zone, multiplied by the volume of freshwater. The total ion intensity contributed by freshwater injection is obtained; and The difference is the difference in ionic strength between the brackish water and the original pore water in the root zone, multiplied by the volume of the brackish water. This yields the total ionic intensity contribution from the brackish water injection. The sum of these two contributions represents the total ionic intensity increment. (Right side) This represents the total increment required for the pore water in the root domain to reach the target ionic strength. The equation holding true means that the ionic strength contribution of the injected water precisely meets the adjustment requirements of the root domain.

[0178] Sulfate concentration equation: ;

[0179] The logic of the sulfate concentration equation is consistent with that of the ionic strength equation. The two terms on the left represent the increase in sulfate concentration due to the injection of freshwater and brackish water, respectively. and The difference multiplied by the volume of fresh water The total amount of sulfate ions contributed by freshwater is obtained; and The difference multiplied by the volume of brackish water This yields the total amount of sulfate contributed by the slightly saline water. The sum of these two amounts represents the total increase in sulfate. (Right side) This represents the total increment required for the root zone pore water to reach the target sulfate concentration. The equation holding true means that the sulfate contribution from the injected water precisely meets the adjustment requirements.

[0180] in, , and These represent the ionic strengths of freshwater, brackish water, and rhizosphere pore water, respectively. , and These represent the sulfate concentrations in freshwater, brackish water, and rhizosphere pore water, respectively. Represents the volume of the root region. and These represent the adjustment amounts for ionic strength and sulfate concentration in root zone pore water, respectively. and Represents the volume of freshwater and brackish water required for a single maintenance cycle;

[0181] like If the ionic strength equation and sulfate concentration equation are combined, the required freshwater volume and brackish water volume for a single maintenance cycle can be calculated; otherwise, return to S1.

[0182] Judgment conditions This is to verify whether the above system of two linear equations has a unique solution. The equation is the determinant of the coefficients of the system. If the determinant is not zero, it indicates that the effects of freshwater and brackish water on ionic strength and sulfate concentration are independent and there is no linear correlation. The volume of freshwater can be uniquely solved by solving the two equations simultaneously. and the volume of slightly saline water This ensures that the calculation of the adjustment amount is accurate and controllable. If the determinant equals 0, it means that the two equations are linearly related, that is, the injection of fresh water and brackish water cannot achieve the target increase in ionic strength and sulfate concentration through independent adjustment. In this case, it is necessary to return to S1 to obtain basic data such as root domain concentration distribution again to eliminate data errors or environmental interference.

[0183] In one embodiment of the invention, fresh water and brackish water volumes required for a single maintenance are applied in the order of first fresh water and then brackish water.

[0184] In detail, freshwater has low ionic strength and a near-zero sulfate concentration. Applying freshwater first can rapidly alter the ionic environment of the rhizosphere pore water due to its low ionic strength: the reduced ionic strength weakens the interaction of charged particles in the solution, promoting radial oxygen permeation in the rhizosphere (because the low ionic strength environment has a more significant impact on the solubility and diffusion coefficient of oxygen). This process primarily affects the spatial position of the concentration ratio peak. By adjusting the rhizosphere redox gradient, the ratio peak is pushed towards the outer edge of the iron film on the root surface, achieving alignment correction (eliminating positional deviation). In this case, the effect of freshwater focuses on changing the ionic strength.

[0185] In detail, brackish water has a higher ionic strength and a significantly higher sulfate concentration than fresh water. After the ionic strength of the fresh water is adjusted and stabilized, the application of brackish water allows the sulfate it carries to precisely replenish the substrate requirements of the rhizosphere sulfur cycle. As a precursor to the conversion of thiosulfate and tetrathiosulfate, changes in sulfate concentration directly affect the conversion rate and equilibrium of these two sulfur forms, thereby regulating the peak curvature of the concentration ratio peak. By enhancing the local conversion efficiency of sulfur intermediates, the peak shape becomes steeper (approaching the reference curvature), achieving focused correction (eliminating curvature deviation). In this case, the effect of brackish water is focused on adjusting the sulfate concentration, and because a stable ionic strength environment has already been established in the fresh water, its regulation of curvature is not affected by drastic fluctuations in ionic strength.

[0186] Example 2

[0187] A coastal wetland vegetation conservation system, comprising, as described in any one of the following claims, a coastal wetland vegetation conservation system:

[0188] The sulfur concentration distribution module is used to obtain the spatial distribution of thiosulfate and tetrathiosulfate concentrations within the root zone.

[0189] The deviation calculation module is used to determine the spatial position and peak curvature of the concentration ratio peak of thiosulfate and tetrathiosulfate based on the spatial distribution of concentration, and at the same time determine the spatial position of the outer edge of the root surface iron film; calculate the positional deviation between the spatial position of the concentration ratio peak and the spatial position of the outer edge of the root surface iron film, and the curvature deviation between the peak curvature of the concentration ratio peak and the reference curvature.

[0190] The data acquisition module is used to determine the root zone volume, as well as the ionic strength and sulfate concentration of the root zone pore water.

[0191] The perturbation response module is used to inject fresh water and brackish water into the root zone through small perturbations, and obtain the spatial position of the concentration ratio peak and the rate of change of the peak shape curvature with the ion intensity and sulfate concentration of the root zone pore water.

[0192] The water chemistry adjustment calculation module is used to calculate the ionic strength adjustment and sulfate concentration adjustment of the root zone pore water based on the position deviation, curvature deviation and rate of change.

[0193] The alternating water consumption calculation module is used to calculate the volume of fresh water and brackish water required for a single maintenance cycle based on the root zone volume, the ionic strength and sulfate concentration of the root zone pore water, as well as the ionic strength and sulfate concentration of fresh water and brackish water.

[0194] The embodiments of this example have been described above. However, this example is not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms based on the guidance of this example, and all of them are within the protection scope of this example.

Claims

1. A method for the maintenance of coastal wetland plants, characterized in that, include: S1, obtain the spatial distribution of thiosulfate and tetrathiosulfate concentrations within the root domain; S2. Based on the spatial distribution of concentration, determine the spatial position and peak curvature of the concentration ratio peak of thiosulfate and tetrathiosulfate, and at the same time determine the spatial position of the outer edge of the root surface iron film; calculate the positional deviation between the spatial position of the concentration ratio peak and the spatial position of the outer edge of the root surface iron film, and the curvature deviation between the peak curvature of the concentration ratio peak and the reference curvature. S3, determine the root domain volume, as well as the ionic strength and sulfate concentration of the root domain pore water; S4. Fresh water and slightly brackish water were injected into the root zone by small perturbation, and the spatial position of the concentration ratio peak and the rate of change of peak shape curvature on the ion intensity and sulfate concentration of the root zone pore water were obtained. S5, based on the positional deviation, curvature deviation and rate of change, the ionic strength adjustment amount and sulfate concentration adjustment amount of the root zone pore water are obtained; S6. Based on the root zone volume, the ionic strength and sulfate concentration of the root zone pore water, as well as the ionic strength and sulfate concentration of fresh water and brackish water, the required fresh water volume and brackish water volume for a single maintenance cycle are calculated.

2. The coastal wetland plant maintenance system according to claim 1, characterized in that, Based on the spatial distribution of concentrations, the spatial location and peak curvature of the concentration ratio peak of thiosulfate and tetrathiosulfate were determined, including: Coordinate points set along the radial direction of the target plant's rhizosphere at preset radial step intervals; The concentration values ​​of thiosulfate and tetrathiosulfate were measured at each coordinate point to form thiosulfate concentration sequences and tetrathiosulfate concentration sequences. Divide the tetrathiosulfate concentration value at each coordinate point by the thiosulfate concentration value to obtain the concentration ratio at the coordinate point, and arrange the coordinate points in order to form a concentration ratio curve. The point with the largest concentration ratio in the concentration ratio curve is taken as the concentration ratio peak, and the coordinates corresponding to the concentration ratio peak are taken as the spatial location of the concentration ratio peak. Using the spatial location of the concentration ratio peak as the center, three adjacent coordinate points are selected to form a three-point neighborhood; the peak curvature of the concentration ratio peak is calculated using the second-order difference method based on the concentration ratio of the three-point neighborhood.

3. The coastal wetland plant maintenance system according to claim 2, characterized in that, Determining the spatial location of the outer edge of the root surface iron film includes: At each coordinate point, the dissolved oxygen concentration and ferric iron indicator signal values ​​were measured to generate dissolved oxygen concentration sequences and ferric iron indicator signal sequences, respectively. The dissolved oxygen concentration sequence and the ferric iron indicator signal sequence were smoothed by the moving average method to obtain the smoothed dissolved oxygen concentration sequence and the smoothed ferric iron indicator signal sequence, respectively. In the smoothed ferric iron indicator signal sequence, the point with the largest smoothed ferric iron indicator signal is taken as the smoothed ferric iron indicator signal peak; the coordinates corresponding to the smoothed ferric iron indicator signal peak are taken as the peak coordinates of the smoothed ferric iron indicator signal peak. The smoothed ferric iron indicator signal at the Nth coordinate point in the smoothed ferric iron indicator signal sequence is taken as the baseline value of the ferric iron signal; where N represents the number of coordinate points. Take half of the difference between the peak value of the smoothed ferric iron indicator signal and the baseline value, and sum it with the baseline value to obtain the half-peak value; The smoothed ferric iron indicator signal sequence is searched radially outward from the first coordinate point. After the peak coordinate, the smoothed ferric iron signal value first drops to half the peak value and crosses two adjacent coordinate points of the half peak value. The spatial position of the outer edge of the root surface iron film is calculated by linear interpolation in the region between the two coordinate points.

4. A coastal wetland plant maintenance system according to claim 3, characterized in that, The spatial deviation of the concentration ratio peak from the outer edge of the root surface iron film and the curvature deviation of the peak shape curvature from the reference curvature are calculated, including: Subtracting the spatial position of the outer edge of the root surface iron film from the spatial position of the concentration ratio peak yields the positional deviation between the spatial position of the concentration ratio peak and the spatial position of the outer edge of the root surface iron film. Subtracting the peak curvature of the concentration ratio peak from the reference curvature yields the curvature deviation between the peak curvature of the concentration ratio peak and the reference curvature.

5. A coastal wetland plant maintenance system according to claim 4, characterized in that, By injecting freshwater and slightly brackish water into the root zone with small perturbations, the spatial location of the concentration ratio peak and the rate of change of peak shape curvature with respect to the ionic strength and sulfate concentration in the root zone pore water were obtained, including: Set the perturbation volume for freshwater and brackish water; where both the perturbation volume for freshwater and brackish water are positive values ​​and do not exceed five percent of the root domain volume; During freshwater and brackish water perturbation processes, the ambient temperature of the root zone was kept constant. The freshwater perturbation process is as follows: A volume of freshwater with a perturbation was injected into the root domain. After the freshwater and the pore water in the root domain were mixed for a first preset time, the first spatial position and the first peak curvature of the concentration ratio peak were remeasured. Calculate the first position increment; where the first position increment is the first spatial position of the concentration ratio peak minus the spatial position of the concentration ratio peak; Calculate the first curvature increment; where the first curvature increment is the first peak shape curvature of the concentration ratio peak minus the peak shape curvature of the concentration ratio peak; The increments of the first ionic strength and the first sulfate concentration are calculated based on the principle of conservation of mixtures, as follows: The first ion intensity increment is obtained by multiplying the difference between the ion intensity of freshwater and the ion intensity of root domain pore water at the current moment by the freshwater perturbation volume and then dividing the product by the root domain volume. The first sulfate concentration increment is obtained by multiplying the difference between the sulfate concentration of freshwater and the sulfate concentration of root zone pore water at the current moment by the freshwater perturbation volume and then dividing the product by the root zone volume. Wait for the preset recovery time; Inject a slightly perturbed volume of slightly saline water into the root zone. After the slightly saline water mixes with the pore water in the root zone for a second preset time, remeasure the second spatial position and second peak curvature of the concentration ratio peak. Calculate the second position increment; where the second position increment is the second spatial position of the concentration ratio peak minus the spatial position of the concentration ratio peak; Calculate the second curvature increment; where the second curvature increment is the second peak curvature of the concentration ratio peak minus the peak curvature of the concentration ratio peak; The increments of the second ionic strength and the second sulfate concentration are calculated based on the principle of conservation of mixing, as follows: The second ion intensity increment is obtained by multiplying the difference between the ion intensity of the brackish water and the ion intensity of the root domain pore water at the current moment by the product of the brackish water perturbation volume and the root domain volume. The second sulfate concentration increment is obtained by multiplying the difference between the sulfate concentration in the brackish water and the sulfate concentration in the root zone pore water at the current moment by the product of the brackish water perturbation volume and the root zone volume. The rate of change is calculated as follows: ； in, Indicates the increment at the first position. Indicates the increment at the second position. Indicates the first curvature increment. This represents the second curvature increment. Indicates the first ionic strength increment. This indicates the second ionic strength increment. This indicates the increase in the first sulfate concentration. This indicates the increase in the concentration of the second sulfate ion. This represents the rate of change of the spatial position of the concentration ratio peak with respect to the ionic intensity of the root domain pore water. This indicates the rate of change of the spatial location of the concentration ratio peak with respect to the sulfate concentration in the root zone pore water. This represents the rate of change in the peak shape curvature of the concentration ratio peak with respect to the ionic intensity of the root zone pore water. This represents the rate of change of the peak shape curvature of the concentration ratio peak with respect to the sulfate concentration in the root zone pore water.

6. A coastal wetland plant maintenance system according to claim 5, characterized in that, Based on the positional deviation, curvature deviation, and rate of change, the ionic strength adjustment and sulfate concentration adjustment of the root zone pore water are calculated, including: Define the target spatial position change of the concentration ratio peak; where the target spatial position change is the negative of the position deviation. Define the target peak curvature change for the concentration ratio peak; where the target peak curvature change is the curvature deviation. The first linear equation is established by relating the spatial position of the concentration ratio peak to the rate of change of ionic intensity in root zone pore water and the spatial position of the concentration ratio peak to the rate of change of sulfate concentration in root zone pore water, as follows: ； A second linear equation is established using the rate of change of the peak shape curvature of the concentration ratio peak with respect to the change of the ionic intensity of the root zone pore water and the rate of change of the peak shape curvature of the concentration ratio peak with respect to the change of the sulfate concentration of the root zone pore water, as follows: ； in, This represents the adjustment amount of ionic strength for the root domain pore water to be solved. The amount of sulfate concentration adjustment to be determined in the root zone pore water. Indicates positional deviation. Indicates curvature deviation; If satisfied If the first and second linear equations are combined, the ionic strength adjustment and sulfate concentration adjustment of the root domain pore water can be calculated; otherwise, return to S1.

7. A coastal wetland plant maintenance system according to claim 6, characterized in that, Based on the root zone volume, the current ionic strength and sulfate concentration of the root zone pore water, as well as the ionic strength and sulfate concentration of freshwater and brackish water, the required freshwater and brackish water volumes for a single maintenance cycle are calculated, including: Based on the principle of mass conservation, the ionic strength equation and sulfate concentration equation are established as follows: Ionic strength equation: ; Sulfate concentration equation: ; in, , and These represent the ionic strengths of freshwater, brackish water, and rhizosphere pore water, respectively. , and These represent the sulfate concentrations in freshwater, brackish water, and rhizosphere pore water, respectively. Represents the volume of the root region. and These represent the adjustment amounts for ionic strength and sulfate concentration in root zone pore water, respectively. and Represents the volume of freshwater and brackish water required for a single maintenance cycle; like If the ionic strength equation and sulfate concentration equation are combined, the required freshwater volume and brackish water volume for a single maintenance cycle can be calculated; otherwise, return to S1.

8. A coastal wetland plant maintenance system according to claim 7, characterized in that, Apply the required volume of fresh water and brackish water for each maintenance cycle, in the order of first fresh water and then brackish water.

9. A coastal wetland vegetation maintenance system, implementing the coastal wetland vegetation maintenance system as described in any one of claims 1-8, characterized in that, include: The sulfur concentration distribution module is used to obtain the spatial distribution of thiosulfate and tetrathiosulfate concentrations within the root zone. The deviation calculation module is used to determine the spatial position and peak curvature of the concentration ratio peak of thiosulfate and tetrathiosulfate based on the spatial distribution of concentration, and at the same time determine the spatial position of the outer edge of the root surface iron film; calculate the positional deviation between the spatial position of the concentration ratio peak and the spatial position of the outer edge of the root surface iron film, and the curvature deviation between the peak curvature of the concentration ratio peak and the reference curvature. The data acquisition module is used to determine the root zone volume, as well as the ionic strength and sulfate concentration of the root zone pore water. The perturbation response module is used to inject fresh water and brackish water into the root zone through small perturbations, and obtain the spatial position of the concentration ratio peak and the rate of change of the peak shape curvature with the ion intensity and sulfate concentration of the root zone pore water. The water chemistry adjustment calculation module is used to calculate the ionic strength adjustment and sulfate concentration adjustment of the root zone pore water based on the position deviation, curvature deviation and rate of change. The alternating water consumption calculation module is used to calculate the volume of fresh water and brackish water required for a single maintenance cycle based on the root zone volume, the ionic strength and sulfate concentration of the root zone pore water, as well as the ionic strength and sulfate concentration of fresh water and brackish water.

Images