Preparation method of soil modifier for improving stability of organic carbon in Poyang Lake wetland

Abstract

The application discloses a kind of preparation methods of soil conditioner for improving the stability of organic carbon in Poyang Lake wetland, and relates to the field of soil improvement, comprising: obtaining original carbon-rich organic material, determining initial carbon-nitrogen ratio and easily oxidizable organic carbon proportion, collecting initial carbon-nitrogen imbalance degree and ammonia-nitrogen leaching concentration;Configure carbon skeleton pre-oxidation intensity, perform pre-oxidation treatment, and obtain stabilized carbon skeleton;Combined with the ammonia-nitrogen leaching concentration, configure the modified amount of inorganic minerals, and obtain mineral-loaded carbon skeleton by mechanical blending;Calculate the synergistic coefficient and determine the final mixing ratio, perform gradient granulation under humidity conditions with matching moisture content, and obtain porous granular material;Based on the synergistic coefficient, the internal pore size distribution of the porous granular material is zoned and gradiently trimmed, and the initial carbon-nitrogen imbalance degree is combined for tolerance matching correction to obtain the final structure-function integrated targeted soil conditioner.The problem of excessive net loss of soil carbon pool organic carbon in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the field of soil improvement, specifically to a method for preparing a soil conditioner to improve the organic carbon stability of Poyang Lake wetlands. Background Technology

[0002] Due to the high amount of fecal input from bird gathering areas, the Poyang Lake wetland has increased the content of total organic carbon and total nitrogen in the wetland water, as well as the number of fecal indicator bacteria in the water, leading to a carbon-nitrogen imbalance in the Poyang Lake wetland.

[0003] Currently, traditional methods increase the soil carbon-to-nitrogen ratio by directly mixing in carbon-rich organic matter such as straw and sawdust, thereby adsorbing and fixing excess inorganic nitrogen from manure input. However, directly mixing in fresh organic matter such as straw and sawdust can strongly stimulate the mineralization of the soil's original organic carbon due to their easy decomposition, resulting in a significant net loss of organic carbon from the soil carbon pool. Summary of the Invention

[0004] This application provides a method for preparing a soil conditioner to improve the stability of organic carbon in Poyang Lake wetlands, addressing the problem of excessive net loss of organic carbon in the soil carbon pool in existing technologies.

[0005] In view of the above problems, this application provides a method for preparing a soil conditioner to improve the organic carbon stability of Poyang Lake wetlands.

[0006] This application provides a method for preparing a soil conditioner to improve the organic carbon stability of Poyang Lake wetlands, the method comprising:

[0007] Obtain raw carbon-rich organic materials, determine the corresponding initial carbon-nitrogen ratio and the proportion of easily oxidizable organic carbon, and collect the initial carbon-nitrogen imbalance and ammonia nitrogen leaching concentration of the target patch soil.

[0008] Based on the initial carbon-nitrogen imbalance and the target repair cycle, the carbon skeleton pre-oxidation intensity is configured, and the original carbon-rich organic material is subjected to pre-oxidation treatment to obtain a stabilized carbon skeleton.

[0009] Based on the specific surface area and functional group abundance of the stabilized carbon skeleton, the cation adsorption capacity correction factor is calculated, and combined with the ammonia nitrogen leaching concentration, the modification dosage of inorganic minerals is dynamically configured, and a mineral-supported carbon skeleton is obtained through mechanical blending.

[0010] Using the initial carbon-nitrogen ratio and the carbon retention rate of the stabilized carbon skeleton as constraints, the synergistic effect coefficient of the mineral-supported carbon skeleton and the inorganic nitrogen passivator is calculated and the final mixing ratio is determined. Gradient granulation is carried out under humidity conditions that match the moisture content of the target patch soil to obtain porous particles with humidity adaptability and carbon-nitrogen synergistic effect.

[0011] Based on the synergistic effect coefficient, the internal pore size distribution of the porous particles is partitioned and gradient-tailed, and the tolerance matching correction is performed in combination with the initial carbon-nitrogen imbalance to obtain the final structure-function integrated targeted soil conditioner.

[0012] Optionally, the original carbon-rich organic material is obtained, the corresponding initial carbon-to-nitrogen ratio and the proportion of easily oxidizable organic carbon are determined, and the initial carbon-to-nitrogen imbalance and ammonia nitrogen leaching concentration of the target patch soil are collected, including:

[0013] Raw carbon-rich organic materials were collected from the shoreline of the bird gathering area in Poyang Lake wetland. After drying and pulverizing, the total carbon and total nitrogen content were determined using an elemental analyzer, and the initial carbon-nitrogen ratio was calculated.

[0014] The original carbon-rich organic material was oxidized by potassium dichromate-sulfuric acid external heating method. Easily oxidizable carbon was extracted with 333-667 mmol / L potassium permanganate solution. The percentage of oxidized carbon to total carbon content was determined as the percentage of easily oxidizable organic carbon.

[0015] One month before and after the seasonal peak of bird droppings, topsoil samples were collected from the target patches using a five-point sampling method. After being mixed evenly, the total inorganic nitrogen and total organic carbon content of the soil were measured.

[0016] The deviation of the ratio of the total inorganic nitrogen to the total organic carbon from the corresponding ratio in the reference area where there is no bird activity in the same region is taken as the initial carbon-nitrogen imbalance.

[0017] Soil pore water from the target patch was collected, filtered through a 0.22–0.65 μm filter membrane, and the concentration of ammonium nitrogen in the filtrate was determined by Nessler's reagent colorimetric method, which was used as the ammonia nitrogen leaching concentration.

[0018] Optionally, based on the initial carbon-nitrogen imbalance and the target remediation cycle, the carbon skeleton pre-oxidation intensity is configured, and the original carbon-rich organic material is subjected to pre-oxidation treatment to obtain a stabilized carbon skeleton, including:

[0019] The ratio of the initial carbon-nitrogen imbalance to the target repair cycle is used as the base oxidation intensity, and the original carbon-rich organic material is pre-oxidized using the base oxidation intensity.

[0020] During the processing, the proportion of easily oxidizable organic carbon in the original carbon-rich organic material is monitored. When the proportion of easily oxidizable organic carbon drops to a stable range that matches the initial carbon-nitrogen imbalance, the oxidation reaction is terminated.

[0021] The material after oxidation termination is washed with deionized water until neutral, vacuum dried at 45-65°C to constant weight, pulverized and sieved, and powder with a particle size of less than 0.25 mm is collected as the stabilized carbon skeleton.

[0022] The stabilized carbon skeleton was subjected to elemental analysis to determine the carbon content after stabilization. The ratio of the carbon content after stabilization to the total carbon content before oxidation was taken as the carbon retention rate.

[0023] When the carbon retention rate is lower than the lower limit of carbon yield that matches the target repair cycle, the basic oxidation intensity is reduced by an amount appropriate to the deviation of the carbon retention rate, and the pre-oxidation treatment is repeated until the carbon retention rate reaches the lower limit of carbon yield and the proportion of easily oxidizable organic carbon drops to a stable range that matches the initial carbon-nitrogen imbalance.

[0024] Optionally, during the treatment process, the proportion of easily oxidizable organic carbon in the original carbon-rich organic material is monitored. When the proportion of easily oxidizable organic carbon drops to a stable range matching the initial carbon-nitrogen imbalance, the oxidation reaction is terminated, including:

[0025] Starting from the beginning of the pre-oxidation treatment, a sample of the original carbon-rich organic material was taken every 30 minutes. The easily oxidizable carbon of the sample was extracted using the potassium dichromate-sulfuric acid external heating method with 333-667 mmol / L potassium permanganate solution, and the proportion of easily oxidizable organic carbon in the sample was determined.

[0026] Based on the initial carbon-nitrogen imbalance, the target repair cycle, and the proportion of easily oxidizable organic carbon, the oxidation termination threshold is determined.

[0027] Based on the initial carbon-nitrogen imbalance and the target repair cycle, a lower limit reference value for the stable range is jointly determined;

[0028] When the proportion of easily oxidizable organic carbon in the sample drops below the oxidation termination threshold for the first time, restore the original oxidation conditions and continue treatment for 5 to 8 minutes. Take a sample again for measurement. If the proportion of easily oxidizable organic carbon measured again still does not exceed the oxidation termination threshold, the reaction endpoint is confirmed to have been reached.

[0029] If the percentage of easily oxidizable organic carbon measured again rebounds to above the oxidation termination threshold, the oxidation process continues and sampling is repeated until the percentage of easily oxidizable organic carbon measured in two consecutive measurements is not higher than the oxidation termination threshold and not lower than the lower limit reference value, at which point the oxidation reaction is terminated.

[0030] Optionally, based on the initial carbon-nitrogen imbalance and the target repair cycle, a lower limit reference value for the stability range is jointly determined, including:

[0031] The ratio of the initial carbon-nitrogen imbalance to the target repair cycle is used as the time pressure coefficient;

[0032] The initial easily oxidizable organic carbon percentage of the original carbon-rich organic material before pre-oxidation treatment is collected, and combined with the time-pressure coefficient, a deep oxidation baseline value is obtained.

[0033] Based on the target repair cycle and the initial carbon-nitrogen imbalance, a repair urgency factor is calculated, wherein the repair urgency factor is inversely proportional to the target repair cycle and directly proportional to the initial carbon-nitrogen imbalance;

[0034] Based on the aforementioned deep oxidation baseline value and the aforementioned repair urgency factor, a lower limit correction weight is determined collaboratively.

[0035] Based on the lower limit correction weight, the oxidation termination threshold is scaled and adjusted to obtain the lower limit reference value of the stable range.

[0036] Optionally, based on the specific surface area and functional group abundance of the stabilized carbon skeleton, a cation adsorption capacity correction factor is calculated, including:

[0037] The specific surface area of ​​the stabilized carbon skeleton was determined by gas adsorption, and the total amount of surface acidic functional groups of the stabilized carbon skeleton was determined by chemical titration, which was used as the functional group abundance.

[0038] The specific surface area and the carbon retention rate are fused to obtain the effective adsorption area, and the density of active adsorption sites is calculated by combining the functional group abundance.

[0039] The initial adsorption capacity is obtained based on the effective adsorption area and the density of active adsorption sites.

[0040] The initial adsorption capacity and the initial carbon-nitrogen imbalance are fused to obtain the cation adsorption capacity correction factor, wherein the cation adsorption capacity correction factor and the initial carbon-nitrogen imbalance have an inverse relationship.

[0041] Optionally, the modification dosage of inorganic minerals can be dynamically configured based on the ammonia nitrogen leaching concentration, including:

[0042] The ammonia nitrogen leaching concentration is multiplied by the initial carbon-nitrogen imbalance, and the resulting product is used as the basic ammonium nitrogen load reflecting the soil ammonium nitrogen retention requirement of the target patch.

[0043] Obtain the functional group abundance of the stabilized carbon framework and the cation adsorption capacity correction factor;

[0044] The functional group abundance is multiplied by the cation adsorption capacity correction factor, and the product is used as the adsorption efficiency index of ammonium nitrogen per unit mass of the stabilized carbon framework.

[0045] Based on the basic ammonium nitrogen loading and the adsorption efficiency index, the mineral content baseline is calculated;

[0046] Based on the target repair cycle and the initial carbon-nitrogen imbalance, the dosage correction coefficient determined collaboratively, combined with the mineral dosage base, is used to calculate the modified dosage;

[0047] Based on the carbon retention rate and the carbon mass fraction of the original carbon-rich organic material, the upper limit of the dosage reflecting the carrying capacity of the stabilized carbon framework for inorganic minerals is determined.

[0048] When the modified dosage exceeds the upper limit of the dosage, the adsorption efficiency index is corrected a second time by the cation adsorption capacity correction factor to obtain the corrected adsorption efficiency index.

[0049] The modified dosage is recalculated based on the basic ammonium nitrogen load and the corrected adsorption efficiency index, and compared again with the upper limit of the dosage. The lower of the two values ​​is taken as the final modified dosage.

[0050] Optionally, constrained by the initial carbon-nitrogen ratio and the carbon retention rate of the stabilized carbon skeleton, the synergistic effect coefficient of the mineral-supported carbon skeleton and the inorganic nitrogen passivator is calculated, and the final mixing ratio is determined. Gradient granulation is then performed under humidity conditions matching the moisture content of the target patch soil to obtain porous particles with humidity adaptability and carbon-nitrogen synergistic effect, including:

[0051] Obtain the final modified dosage of the mineral-supported carbon framework and the cation adsorption capacity correction factor;

[0052] The initial carbon-nitrogen ratio and the carbon retention rate are fused to obtain the carbon skeleton stability index, and combined with the final modified doping amount, the potential retention capacity of the mineral-supported carbon skeleton for ammonium nitrogen is obtained.

[0053] The specific surface area and active component content of the inorganic nitrogen passivating agent are obtained, and the corresponding nitrogen passivation efficiency index is calculated. Combined with the potential retention capacity, the synergistic enhancement coefficient is determined.

[0054] The mass ratio of the mineral-supported carbon skeleton to the inorganic nitrogen passivating agent is determined by the synergistic effect coefficient and used as the final mixing ratio.

[0055] The moisture content of the target patch soil is collected, and the mineral-supported carbon skeleton and the inorganic nitrogen passivating agent are mixed according to the final mixing ratio. Then, under humidity conditions that match the moisture content, gradient granulation is carried out with progressively increasing granulation pressure to obtain the humidity-adapted and carbon-nitrogen synergistic porous particles.

[0056] Optionally, under humidity conditions matching the moisture content, gradient granulation is performed with progressively increasing granulation pressure to obtain the humidity-adapted and carbon-nitrogen synergistic porous particles, including:

[0057] The soil moisture content of the target patch is collected, and the humidity of the granulation environment is adjusted to be within ±3% of the moisture content.

[0058] After the mineral-supported carbon skeleton and the inorganic nitrogen passivator are mixed evenly according to the final mixing ratio, the mixture is placed in a granulation environment to allow it to stand and adjust the humidity so that the moisture content of the mixture reaches equilibrium with the ambient humidity.

[0059] The conditioned mixture is extruded and molded under an initial granulation pressure to obtain a particle core, wherein the initial granulation pressure is determined by the carbon retention rate, and the lower the carbon retention rate, the higher the initial granulation pressure.

[0060] Based on the particle core, a multi-stage pressurization densification process is performed with progressively increasing granulation pressure, wherein the increment of each pressure stage is determined by the synergistic enhancement coefficient and the carbon retention rate.

[0061] After multi-stage pressurization, the particles are left to stand and solidify in the granulation environment to obtain the humidity-adapted and carbon-nitrogen synergistic porous particles.

[0062] Optionally, based on the synergistic effect coefficient, the internal pore size distribution of the porous particles is partitioned and gradient-tailed, and tolerance matching correction is performed in conjunction with the initial carbon-nitrogen imbalance to obtain the final structure-function integrated targeted soil conditioner, including:

[0063] When the synergistic effect coefficient is greater than 1, the internal pore size of the porous particles is divided into three regions radially from the inside to the outside: a dense core layer, a transition buffer layer, and a porous outer shell layer.

[0064] When the synergistic effect coefficient is not greater than 1, the internal pore size of the porous particles is divided into three regions from the inside to the outside along the radial direction: a porous core layer, a transition buffer layer, and a dense outer shell layer.

[0065] Based on the synergistic effect coefficient, the aperture range and layer thickness ratio of each region are determined. The greater the deviation of the synergistic effect coefficient from 1, the more significant the aperture difference between adjacent regions.

[0066] The initial carbon-nitrogen imbalance is obtained, and the initial carbon-nitrogen imbalance is compared with the target pore size of the outermost region of the porous particles to calculate the tolerance deviation.

[0067] Calculate the difference between the tolerance deviation magnitude and the tolerance threshold, and determine the scaling correction magnitude based on the difference and the initial carbon-nitrogen imbalance, wherein the tolerance threshold is the allowable upper limit of deviation jointly determined by the carbon retention rate and the target repair cycle;

[0068] The target pore size of the outermost region of the porous particles is scaled and corrected using the scaling correction range to obtain the corrected outermost pore size, and the difference between the outermost pore size before and after correction is calculated as the pore size correction amount.

[0069] Obtain the ratio of the kernel layer and the transition layer to the thickness of the layer, and allocate the aperture correction amount to the kernel layer and the transition layer according to the ratio.

[0070] When the outermost aperture shrinks, the allocated correction amount is superimposed on the core layer aperture and the transition layer aperture accordingly.

[0071] When the outermost pore size expands, the allocated correction amount is subtracted from the corresponding core layer pore size and the transition layer pore size to keep the total pore volume inside the porous particles constant.

[0072] The particles with modified pore size are thermally stabilized in an inert atmosphere to obtain the structure-function integrated targeted soil conditioner.

[0073] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0074] This application provides a method for preparing a soil conditioner to improve the stability of organic carbon in Poyang Lake wetlands. First, raw carbon-rich organic materials are obtained, and the initial carbon-to-nitrogen ratio and the proportion of easily oxidizable organic carbon are measured. The initial carbon-to-nitrogen imbalance and ammonia nitrogen leaching concentration are collected to provide a data basis for subsequent calculations. The pre-oxidation intensity of the carbon skeleton is configured, and pre-oxidation treatment is performed to obtain a stabilized carbon skeleton, providing a data basis for subsequent dosage configuration, improving the accuracy of corrections, and enhancing the robustness and repeatability of the process. The cation adsorption capacity correction factor is calculated, and combined with the ammonia nitrogen leaching concentration, the modification dosage of inorganic minerals is configured, and then mechanically... Blending yields a mineral-supported carbon skeleton, providing a scientific input for determining the required mineral content. The synergistic effect coefficient between the mineral-supported carbon skeleton and the inorganic nitrogen passivator is calculated, and the final blending ratio is determined. Gradient granulation is then performed under humidity conditions with matched moisture content to obtain porous particles. Based on the synergistic effect coefficient, the internal pore size distribution of the porous particles is partitioned and gradient-tailed. Tolerance matching correction is performed in conjunction with the initial carbon-nitrogen imbalance to improve the physical stability of the particles in the target soil. Finally, a structure-function integrated targeted soil conditioner is obtained, enhancing the applicability and long-term remediation effect of the soil conditioner. Attached Figure Description

[0075] Figure 1 This is a schematic flowchart of a method for preparing a soil conditioner to improve the organic carbon stability of Poyang Lake wetlands, as provided in this application.

[0076] Figure 2This is a schematic diagram of the process for obtaining porous particles in a method for preparing a soil conditioner to improve the stability of organic carbon in Poyang Lake wetlands, as provided in this application. Detailed Implementation

[0077] This application provides a method for preparing a soil conditioner to improve the stability of organic carbon in Poyang Lake wetlands, specifically addressing the problem of excessive net loss of organic carbon in the soil carbon pool in existing technologies.

[0078] The present invention will now be described in detail with reference to the accompanying drawings.

[0079] Examples, such as Figure 1 As shown, this application provides a method for preparing a soil conditioner to improve the organic carbon stability of Poyang Lake wetlands, the method comprising:

[0080] S10: Obtain the original carbon-rich organic material, determine the corresponding initial carbon-nitrogen ratio and the proportion of easily oxidizable organic carbon, and collect the initial carbon-nitrogen imbalance and ammonia nitrogen leaching concentration of the target patch soil.

[0081] In this embodiment, the original carbon-rich organic material is an organic solid substance that has not undergone any chemical or biological modification treatment and whose carbon mass fraction is significantly higher than its nitrogen mass fraction; the initial carbon-nitrogen ratio is the ratio of the total organic carbon mass to the total nitrogen mass in the original carbon-rich organic material, reflecting the stoichiometric characteristics of the material's own carbon and nitrogen elements.

[0082] The percentage of readily oxidizable organic carbon is the percentage of the total carbon mass of organic carbon in the original carbon-rich organic material that can be oxidized by potassium permanganate solution with a concentration of 333–667 mmol / L. It represents the chemical activity and biodegradability of the organic carbon components in the material. The target patch soil is a local soil unit in the bird gathering area of ​​Poyang Lake wetland, which has a carbon-nitrogen imbalance due to long-term or seasonal high input of bird droppings.

[0083] The initial carbon-nitrogen imbalance is the ratio of the current total inorganic nitrogen to the total organic carbon in the target patch soil, and the deviation of this ratio from the corresponding ratio in a bird-free reference area within the same wetland system; the ammonia nitrogen leaching concentration is the mass concentration of ammonium nitrogen extracted from the pore water of the target patch soil and measured.

[0084] Specifically, firstly, wetland soil was uniformly collected from the Poyang Lake wetland area to obtain the original carbon-rich organic matter. The original carbon-rich organic matter was then analyzed to determine the initial carbon-to-nitrogen ratio and the proportion of easily oxidizable organic carbon. Simultaneously, the initial carbon-to-nitrogen imbalance and ammonia nitrogen leaching concentration of the target soil patches requiring improvement were collected.

[0085] Step S10 in the method provided in this embodiment of the invention includes:

[0086] Raw carbon-rich organic materials were collected from the shoreline of the bird gathering area in Poyang Lake wetland. After drying and pulverizing, the total carbon and total nitrogen content were determined using an elemental analyzer, and the initial carbon-nitrogen ratio was calculated.

[0087] The original carbon-rich organic material was oxidized by potassium dichromate-sulfuric acid external heating method. Easily oxidizable carbon was extracted with 333-667 mmol / L potassium permanganate solution. The percentage of oxidized carbon to total carbon content was determined as the percentage of easily oxidizable organic carbon.

[0088] One month before and after the seasonal peak of bird droppings, topsoil samples were collected from the target patches using a five-point sampling method. After being mixed evenly, the total inorganic nitrogen and total organic carbon content of the soil were measured.

[0089] The deviation of the ratio of the total inorganic nitrogen to the total organic carbon from the corresponding ratio in the reference area where there is no bird activity in the same region is taken as the initial carbon-nitrogen imbalance.

[0090] Soil pore water from the target patch was collected, filtered through a 0.22–0.65 μm filter membrane, and the concentration of ammonium nitrogen in the filtrate was determined by Nessler's reagent colorimetric method, which was used as the ammonia nitrogen leaching concentration.

[0091] In this embodiment, soil is first uniformly collected from the shoreline of the Poyang Lake wetland bird gathering area to obtain raw carbon-rich organic materials, such as the litter of emergent plants like reeds and sedges. These materials are then dried and pulverized using drying and pulverizing equipment, and free water is removed by natural air drying or low-temperature drying. The resulting powder is then mechanically ground or sheared and filtered through a sieve of a certain mesh size to obtain a homogeneous powder of the raw carbon-rich organic materials. Subsequently, the total carbon and total nitrogen content are determined using an elemental analyzer, and the initial carbon-nitrogen ratio is calculated based on the measured total carbon and total nitrogen content.

[0092] The initial carbon-to-nitrogen ratio (CNR) = total carbon content / total nitrogen content. The CNR reflects the stoichiometric characteristics of carbon and nitrogen elements in a material and is a fundamental parameter for evaluating its ability to regulate soil carbon-nitrogen balance as a carbon source. For example, dividing the instrument's output of a total carbon mass fraction of 45.2% and a total nitrogen mass fraction of 0.65% yields an initial CNR of approximately 45.2% / 0.65% ≈ 69.5.

[0093] Secondly, the original carbon-rich organic material was oxidized using the potassium dichromate-sulfuric acid external heating method. Specifically, according to the potassium dichromate-sulfuric acid external heating method, in the presence of excess concentrated sulfuric acid, the strong oxidizing property of potassium dichromate was used to oxidize organic carbon into carbon dioxide. The amount of remaining potassium dichromate was measured, and the organic carbon content was indirectly calculated.

[0094] Then, another portion of the same sample powder was added to a 600 mmol / L potassium permanganate solution. Easily oxidizable carbon was extracted using a potassium permanganate solution at a concentration of 333–667 mmol / L. This 333–667 mmol / L potassium permanganate solution is a moderately strong oxidizing agent used to extract easily oxidizable organic carbon components from the sample. This concentration range is the recommended concentration for determining easily oxidizable organic carbon in soil according to national forestry standards.

[0095] After the reaction, the mixture was centrifuged and filtered. The supernatant was collected, and the amount of potassium permanganate consumed was measured at 525 nm using a spectrophotometer. The content of easily oxidizable carbon was calculated based on the consumption. Subsequently, the percentage of oxidized carbon to the total carbon content was measured and multiplied by 100% to obtain the percentage of easily oxidizable organic carbon. For example, if the total carbon content is 45.2% and the amount of carbon oxidized by potassium permanganate is 18.1%, then the percentage is 40.0%.

[0096] Secondly, topsoil samples were collected from target patches one month before and after the peak seasonal input period of bird droppings, using a five-point sampling method. This peak seasonal input period is a specific time when migratory birds in Poyang Lake wetlands, such as white cranes and swans, migrate in large numbers and generate significant amounts of droppings, typically from November to February of the following year. During this period, the droppings flux reaches its annual peak. The five-point sampling method is a standard environmental soil sampling scheme, involving collecting soil samples at the center point, at four equidistant points in four directions, and at the center point itself within a selected representative plot. Topsoil, the soil layer extending 0–20 cm below the surface, is the first layer that bird droppings come into contact with and accumulate upon input.

[0097] Specifically, two samplings were conducted one month before and after the peak period of bird droppings input: the first before the start of the input period, such as in October, to collect background values; and the second after the input period, such as in March, to collect soil conditions after the pollution peak. During each sampling, topsoil samples were collected from depths of 0–20 cm at five points within pre-selected targeted remediation patches for carbon and nitrogen imbalance. The five subsamples were mixed on-site, placed in sealed bags, and brought back to the laboratory. After removing plant debris and gravel, the samples were air-dried, ground, and sieved.

[0098] After mixing thoroughly, the total inorganic nitrogen content of the soil was determined using the potassium chloride extraction-flow analyzer method. This method involves extracting the soil sample with potassium chloride solution to allow inorganic nitrogen such as ammonium nitrogen and nitrate nitrogen to enter the solution. The extract is then injected into a flow analyzer, and the inorganic nitrogen content is calculated by colorimetric detection after a colorimetric reaction.

[0099] The total organic carbon in soil is determined by the potassium dichromate-sulfuric acid external heating method. This involves adding an excess of a potassium dichromate-concentrated sulfuric acid mixture under external heating conditions to oxidize the soil organic carbon. The remaining potassium dichromate is then titrated with a ferrous sulfate standard solution. The organic carbon content is calculated based on the amount of potassium dichromate consumed. The potassium chloride extraction-flow analyzer method is the standard method for determining inorganic nitrogen in soil, while the potassium dichromate-sulfuric acid external heating method is the classic method for determining soil organic carbon. Both are universally accepted standards in the field of soil science.

[0100] Furthermore, the ratio of total inorganic nitrogen to total organic carbon is calculated. The deviation of this ratio from the corresponding ratio in the reference area with no bird activity in the same region is taken as the initial carbon-nitrogen imbalance. Initial carbon-nitrogen imbalance = Ratio of total inorganic nitrogen to total organic carbon - Corresponding ratio in the reference area with no bird activity in the same region.

[0101] For example, assuming a target patch soil sample exists, its total inorganic nitrogen content is measured, for example, ammonium nitrogen 120 mg / kg and nitrate nitrogen 30 mg / kg = 150 mg / kg; total organic carbon = 30000 mg / kg, and the ratio is calculated as 150 / 30000 = 0.005. Simultaneously, soil from the same layer in a reference area without bird activity is collected, and its total inorganic nitrogen content is measured using the same method, resulting in 20 mg / kg of inorganic nitrogen and 40000 mg / kg of organic carbon, with a ratio calculated as 20 / 40000 = 0.0005. Then the initial carbon-nitrogen imbalance is 0.005 - 0.0005 = 0.0045.

[0102] Ultimately, soil pore water, which fills the non-capillary and capillary pores between soil aggregates, is the primary liquid phase medium for the migration and transformation of dissolved substances in the soil; the 0.22–0.65 μm filter membrane is a microporous filter membrane with a pore size between 0.22 and 0.65 micrometers. This pore size range ensures that the measurement results represent the true concentration of the dissolved phase.

[0103] Nessler's reagent colorimetric method is a classic method for the quantitative analysis of ammonium nitrogen. Nessler's reagent reacts with ammonium nitrogen in water under alkaline conditions to form a yellow-brown mercuric ammonium iodide complex. The color of the complex is directly proportional to the concentration of ammonium nitrogen, and the absorbance can be measured at a wavelength of 420 nm using a spectrophotometer. The concentration can then be calculated using a standard curve.

[0104] Specifically, while collecting soil samples from the target patch, approximately 100g of undisturbed fresh soil from the same sampling point was immediately placed in a centrifuge tube and centrifuged at 4000 rpm for 15 minutes. The supernatant was collected as soil pore water. If the soil moisture content was too low to be centrifuged, a negative pressure filtration device could be used for in-situ collection. The collected pore water was then vacuum filtered through a filter membrane in the range of 0.22–0.65 μm. The initial filtrate was discarded, and the subsequent filtrate was collected. A certain volume of the filtrate was accurately transferred, Nessler's reagent and potassium sodium tartrate masking agent were added, and after 10 minutes of color development, the absorbance was measured at a wavelength of 420 nm. The absorbance was then substituted into a pre-prepared ammonium nitrogen standard curve to calculate the concentration of ammonium nitrogen in the filtrate.

[0105] In this embodiment of the application, by limiting the sampling timing, standardizing the analysis method, and using the five-point sampling method, a highly operable, repeatable baseline parameter acquisition scheme that eliminates environmental heterogeneity interference is provided for the preparation method.

[0106] S20: Based on the initial carbon-nitrogen imbalance and the target repair cycle, configure the carbon skeleton pre-oxidation intensity, and perform pre-oxidation treatment on the original carbon-rich organic material to obtain a stabilized carbon skeleton.

[0107] In this embodiment, the carbon skeleton pre-oxidation intensity is the overall severity of the reaction conditions used when oxidizing the original carbon-rich organic material; the stabilized carbon skeleton is the residual solid product with low biodegradability and high chemical stability after the original carbon-rich organic material has undergone pre-oxidation treatment with a specific intensity.

[0108] Specifically, a reasonable base oxidation intensity is configured based on the measured initial carbon-nitrogen imbalance and target remediation cycle. Then, the raw material is pre-oxidized under this intensity condition. By controlling the oxidant concentration and pyrolysis temperature, the proportion of easily oxidizable organic carbon is reduced to a stable range that matches the initial carbon-nitrogen imbalance. The stabilized carbon support after treatment is the stabilized carbon skeleton.

[0109] Step S20 in the method provided in this embodiment of the invention includes:

[0110] The ratio of the initial carbon-nitrogen imbalance to the target repair cycle is used as the base oxidation intensity, and the original carbon-rich organic material is pre-oxidized using the base oxidation intensity.

[0111] During the processing, the proportion of easily oxidizable organic carbon in the original carbon-rich organic material is monitored. When the proportion of easily oxidizable organic carbon drops to a stable range that matches the initial carbon-nitrogen imbalance, the oxidation reaction is terminated.

[0112] The material after oxidation termination is washed with deionized water until neutral, vacuum dried at 45-65°C to constant weight, pulverized and sieved, and powder with a particle size of less than 0.25 mm is collected as the stabilized carbon skeleton.

[0113] The stabilized carbon skeleton was subjected to elemental analysis to determine the carbon content after stabilization. The ratio of the carbon content after stabilization to the total carbon content before oxidation was taken as the carbon retention rate.

[0114] When the carbon retention rate is lower than the lower limit of carbon yield that matches the target repair cycle, the basic oxidation intensity is reduced by an amount appropriate to the deviation of the carbon retention rate, and the pre-oxidation treatment is repeated until the carbon retention rate reaches the lower limit of carbon yield and the proportion of easily oxidizable organic carbon drops to a stable range that matches the initial carbon-nitrogen imbalance.

[0115] In this embodiment of the application, firstly, the target remediation period of the target soil patch is obtained. The target remediation period is the length of time required from the application of the soil amendment to the expected carbon and nitrogen balance remediation target. It is usually expressed in days or months and is preset by the wetland management according to the ecological restoration plan.

[0116] The ratio of the initial carbon-nitrogen imbalance to the target remediation period was then calculated, and this ratio was used as the baseline oxidation intensity. A higher ratio indicates a more severe imbalance or a more urgent remediation period, requiring a higher oxidation intensity. The original carbon-rich organic material was then pre-oxidized using this baseline oxidation intensity.

[0117] Specifically, pre-oxidation treatment involves applying a controlled chemical oxidation process to raw carbon-rich organic materials to selectively remove highly reactive, easily oxidizable organic carbon components. Commonly used oxidation methods include, but are not limited to, wet oxidation with hydrogen peroxide, alkaline oxidation with sodium hypochlorite, or ozone gas phase oxidation. Treatment conditions can be configured based on the baseline oxidation intensity.

[0118] Secondly, during the pre-oxidation process, samples are taken and analyzed at fixed time intervals, such as every 30 minutes, to detect the proportion of easily oxidizable organic carbon in the original carbon-rich organic material. When the proportion of easily oxidizable organic carbon drops to a stable range that matches the initial carbon-nitrogen imbalance, the oxidation reaction is immediately stopped by means of rapid cooling, dilution of the oxidant, or addition of a reducing agent to prevent unnecessary loss of the carbon skeleton due to over-oxidation.

[0119] Next, collect the solid residue from the material after oxidation termination. Place the residue in a Buchner funnel and repeatedly wash the solid material after oxidation termination with deionized water with a resistivity ≥18.2 MΩ·cm until the pH value of the washing solution reaches 6.5–7.5, achieving neutrality. Then, vacuum dry it at 45–65°C and a negative pressure such as -0.09 MPa. By initiating pyrolysis or oxidation of the carbon skeleton through vacuum drying, dry to constant weight, pulverize and sieve, and collect the powder with a particle size less than 0.25 mm as the stabilized carbon skeleton. Constant weight is the state where the difference in mass between two consecutive drying cycles does not exceed 0.3%, indicating that the moisture has been completely removed.

[0120] Furthermore, the stabilized carbon skeleton was subjected to elemental analysis using an elemental analyzer to determine the carbon content after stabilization. The ratio of the stabilized carbon content to the total carbon content before oxidation was taken as the carbon retention rate. The carbon retention rate is the percentage of the total carbon mass in the stabilized carbon skeleton to the total carbon mass in the original carbon-rich organic material. Carbon retention rate = Stabilized carbon content / Original carbon content. For example, if 100g of original reed straw has a carbon content of 45g, and the stabilized carbon skeleton has a carbon content of 33g, then the carbon retention rate = 33 / 45 = 73.3%.

[0121] Finally, after calculating the actual carbon retention rate, it is compared with the lower limit of carbon yield pre-stored according to the target remediation period. The lower limit of carbon yield is a preset threshold matched to the target remediation period, representing the minimum carbon retention rate that must be guaranteed to stabilize the carbon skeleton within the target remediation period. The shorter the target remediation period, the higher the lower limit of carbon yield; the longer the target remediation period, the lower limit of carbon yield can be appropriately lowered.

[0122] When the carbon retention rate is greater than or equal to the lower limit of carbon yield matching the target repair cycle, and the proportion of easily oxidized organic carbon has dropped to a stable range, such as 5% to 12%, it is considered qualified and the preparation of the stabilized carbon skeleton is completed.

[0123] When the carbon retention rate falls below the lower limit of carbon yield matching the target remediation cycle, it indicates over-oxidation. The pre-oxidation treatment is then repeated after lowering the base oxidation intensity by an amount appropriate to the deviation in carbon retention rate. The deviation is defined as the ratio of |lower limit of carbon yield for the target remediation cycle - carbon retention rate| / lower limit of carbon yield. The reduction amount is set to the deviation multiplied by the reduction ratio. The new base oxidation intensity = base oxidation intensity × (1 - reduction amount).

[0124] Then, new original carbon-rich organic material samples were collected, and pre-oxidation treatment was performed again according to the new baseline oxidation intensity. The endpoint judgment and carbon retention rate were determined again until the carbon retention rate reached the lower limit of carbon yield and the proportion of easily oxidizable organic carbon dropped to a stable range that matched the initial carbon-nitrogen imbalance.

[0125] In the method provided by this invention embodiment, during the processing, the proportion of easily oxidizable organic carbon in the original carbon-rich organic material is monitored. When the proportion of easily oxidizable organic carbon drops to a stable range matching the initial carbon-nitrogen imbalance, the oxidation reaction is terminated, including:

[0126] Starting from the beginning of the pre-oxidation treatment, a sample of the original carbon-rich organic material was taken every 30 minutes. The easily oxidizable carbon of the sample was extracted using the potassium dichromate-sulfuric acid external heating method with 333-667 mmol / L potassium permanganate solution, and the proportion of easily oxidizable organic carbon in the sample was determined.

[0127] Based on the initial carbon-nitrogen imbalance, the target repair cycle, and the proportion of easily oxidizable organic carbon, the oxidation termination threshold is determined.

[0128] Based on the initial carbon-nitrogen imbalance and the target repair cycle, a lower limit reference value for the stable range is jointly determined;

[0129] When the proportion of easily oxidizable organic carbon in the sample drops below the oxidation termination threshold for the first time, restore the original oxidation conditions and continue treatment for 5 to 8 minutes. Take a sample again for measurement. If the proportion of easily oxidizable organic carbon measured again still does not exceed the oxidation termination threshold, the reaction endpoint is confirmed to have been reached.

[0130] If the percentage of easily oxidizable organic carbon measured again rebounds to above the oxidation termination threshold, the oxidation process continues and sampling is repeated until the percentage of easily oxidizable organic carbon measured in two consecutive measurements is not higher than the oxidation termination threshold and not lower than the lower limit reference value, at which point the oxidation reaction is terminated.

[0131] In this embodiment, starting from the beginning of the pre-oxidation treatment, sampling is performed every 30 minutes to obtain a subsample of the original carbon-rich organic material. This subsample is a small portion extracted from the main reaction system during the pre-oxidation reaction and is used for offline analysis. The subsample should be representative to avoid bias caused by uneven local reactions; for example, 1-2 g should be taken. The subsample is washed with excess deionized water to terminate further oxidation, and then dried and ground according to standard procedures.

[0132] Subsequently, the total carbon content of the sample was determined by the potassium dichromate-sulfuric acid external heating method; then, the easily oxidizable carbon components were extracted by oxidation with potassium permanganate solution ranging from 333 to 667 mmol / L; the percentage of oxidized carbon to the total carbon content was calculated, which is the easily oxidizable organic carbon percentage of the sample. The operation was repeated to obtain multiple easily oxidizable organic carbon percentage values ​​that decreased over time.

[0133] Secondly, based on the initial carbon-nitrogen imbalance, the target remediation period, and the proportion of easily oxidizable organic carbon, an oxidation termination threshold is determined. This threshold is a preset upper limit for the proportion of easily oxidizable organic carbon. When the measured proportion of a sample first falls below this threshold, it indicates that the unstable components of the material have been removed to an acceptable level, entering a candidate state for termination. This threshold can be dynamically determined using a specific algorithm based on the initial carbon-nitrogen imbalance, the target remediation period, and the initial proportion of easily oxidizable organic carbon in the material.

[0134] Before starting the pre-oxidation treatment, the initial carbon-nitrogen imbalance of the target patch, the pre-set target remediation cycle, and the initial easily oxidizable organic carbon ratio of the original carbon-rich organic material are used to calculate the oxidation termination threshold to be used for the current batch in real time according to the functional relationship of the input parameters or the lookup table rules. Oxidation termination threshold = (initial easily oxidizable organic carbon ratio × target remediation cycle) / initial carbon-nitrogen imbalance.

[0135] The higher the initial carbon-nitrogen imbalance, the shorter the target repair cycle, and the greater the initial proportion of easily oxidizable organic carbon, the lower the oxidation termination threshold should be set, requiring more thorough oxidation.

[0136] Furthermore, based on the initial carbon-nitrogen imbalance and the target repair cycle, a lower limit reference value for the stable range is jointly determined. The larger the initial carbon-nitrogen imbalance or the shorter the target repair cycle, the more urgent the repair is, and the lower the lower limit reference value is, allowing for more thorough oxidation. Conversely, the smaller the initial carbon-nitrogen imbalance and the longer the target repair cycle, the higher the lower limit reference value is, preventing excessive oxidation.

[0137] Furthermore, during continuous monitoring, when the proportion of easily oxidizable carbon in a subsample first appears, and this proportion first drops below the oxidation termination threshold, the system continues to run for a short period at the original oxidant concentration, temperature, and stirring speed. This allows the overall average reaction rate of the system to approach the localized level represented by the subsample, and also verifies whether the target value is stable.

[0138] Restore the original oxidation conditions and continue treatment for 5–8 minutes, then take another sample for measurement. If the percentage of easily oxidizable organic carbon still does not exceed the oxidation termination threshold, the reaction has been confirmed to have stably reached the termination condition, and the reaction can be terminated.

[0139] Finally, if the percentage of easily oxidizable organic carbon measured again reaches or exceeds the oxidation termination threshold, it indicates that the initial achievement of the standard was a false result caused by local over-oxidation or sampling error, and the average oxidation degree of the main reaction system has not yet reached the standard. In this case, the oxidation treatment will continue under the original conditions.

[0140] After processing for a certain period of time, samples are taken again for measurement and verification. The endpoint is confirmed and oxidation is terminated when the percentage of easily oxidizable organic carbon in two consecutive measurements is not higher than the oxidation termination threshold and not lower than the lower limit reference value. If the second verification value rises, the cycle continues.

[0141] The method provided in this embodiment of the invention determines a lower limit reference value of the stability range based on the initial carbon-nitrogen imbalance and the target repair cycle, including:

[0142] The ratio of the initial carbon-nitrogen imbalance to the target repair cycle is used as the time pressure coefficient;

[0143] The initial easily oxidizable organic carbon percentage of the original carbon-rich organic material before pre-oxidation treatment is collected, and combined with the time-pressure coefficient, a deep oxidation baseline value is obtained.

[0144] Based on the target repair cycle and the initial carbon-nitrogen imbalance, a repair urgency factor is calculated, wherein the repair urgency factor is inversely proportional to the target repair cycle and directly proportional to the initial carbon-nitrogen imbalance;

[0145] Based on the aforementioned deep oxidation baseline value and the aforementioned repair urgency factor, a lower limit correction weight is determined collaboratively.

[0146] Based on the lower limit correction weight, the oxidation termination threshold is scaled and adjusted to obtain the lower limit reference value of the stable range.

[0147] In this embodiment, the ratio of the initial carbon-nitrogen imbalance to the target remediation period is first used as the time pressure coefficient. The time pressure coefficient represents the degree of imbalance that needs to be addressed per unit time, and is calculated as: Time Pressure Coefficient = Initial Carbon-Nitrogen Imbalance / Target Remediation Period. A larger time pressure coefficient indicates a more urgent remediation task, requiring the removal of more easily oxidized carbon from the material per unit time. For example, if the initial carbon-nitrogen imbalance is 4.5 and the pre-set target remediation period is 90 days, the time pressure coefficient is 4.5 / 90 = 0.05.

[0148] Secondly, the initial readily oxidizable organic carbon percentage of the original carbon-rich organic material before pre-oxidation treatment is collected. Combined with the time-pressure coefficient, a deep oxidation baseline value is obtained. The deep oxidation baseline value = initial readily oxidizable organic carbon percentage × (initial carbon-nitrogen imbalance / target remediation period). The deep oxidation baseline value represents the required oxidation depth under the current time pressure. A larger target remediation period requires a smaller deep oxidation baseline value, meaning it requires oxidation to a lower level of remaining readily oxidizable carbon.

[0149] Next, based on the target repair cycle and the initial carbon-nitrogen imbalance, a repair urgency factor is calculated: Repair Urgency Factor = Initial Carbon-Nitrogen Imbalance / (1 + Target Repair Cycle). The repair urgency factor is inversely proportional to the target repair cycle and directly proportional to the initial carbon-nitrogen imbalance. The repair urgency factor increases with the increase of the initial carbon-nitrogen imbalance and decreases with the increase of the target repair cycle. It is typically expressed as a nonlinear function to reflect the marginal effects in practical engineering.

[0150] Furthermore, based on the deep oxidation baseline value and the repair urgency factor, a lower limit correction weight is collaboratively determined: Lower limit correction weight = Deep oxidation baseline value / (Deep oxidation baseline value + Repair urgency factor). The lower limit correction weight is a dimensionless coefficient used to scale and adjust the oxidation termination threshold to obtain the final lower limit reference value. This achieves a comprehensive balance between the ideal value and the urgency factor, allowing the final lower limit reference value to smoothly adapt to different scenarios.

[0151] Finally, based on the lower limit correction weight, the oxidation termination threshold is scaled and adjusted, that is, the lower limit correction weight is multiplied by the oxidation termination threshold to obtain the lower limit reference value of the stable range. The lower limit reference value = oxidation termination threshold × lower limit correction weight. The lower limit reference value shows that in urgent scenarios, the reference value range is wider and the lower limit is extremely low, allowing for more thorough oxidation; in relaxed scenarios, the reference value range is extremely narrow, allowing for precise control.

[0152] In this embodiment, highly reactive, easily oxidizable organic carbon components are selectively removed through controllable pre-oxidation treatment and carbon retention rate feedback adjustment, resulting in a stabilized carbon framework with low biodegradability. This avoids the induced mineralization effect caused by the addition of fresh organic matter and improves the stability of exogenous organic carbon. The basic oxidation intensity is dynamically configured by the ratio of the target remediation cycle to the initial carbon-nitrogen imbalance, and the pre-oxidation process can be adaptively adjusted according to the remediation urgency of different plaques by correlating the lower limit of carbon yield with the target remediation cycle. By simultaneously monitoring the proportion of easily oxidizable organic carbon and the carbon retention rate, a constraint and closed-loop optimization mechanism for the degree of stabilization and the amount of carbon preserved is established. Finally, through real-time monitoring, endpoint verification, and feedback, the preparation method can automatically adapt to batch differences in raw materials and environmental fluctuations, improving the robustness and repeatability of the process.

[0153] S30: Based on the specific surface area and functional group abundance of the stabilized carbon skeleton, calculate the cation adsorption capacity correction factor, and combine it with the ammonia nitrogen leaching concentration to dynamically configure the modified dosage of inorganic minerals, and obtain a mineral-supported carbon skeleton through mechanical blending.

[0154] In the embodiments of this application, the specific surface area is the total surface area of ​​a unit mass of stabilized carbon skeleton, including the inner and outer surfaces, and its value determines the number of physical adsorption sites; the functional group abundance is the total amount of active chemical groups carried on the surface of the stabilized carbon skeleton that can interact with cations through electrostatic attraction, ion exchange or complexation.

[0155] The cation adsorption capacity correction factor is a dimensionless coefficient used to correct the cation exchange capacity calculated based on ideal conditions. Inorganic minerals are natural or artificial mineral materials with high cation exchange capacity and adsorption performance, including but not limited to zeolite and bentonite, which enhance the adsorption and retention capacity of the carbon skeleton for ammonia nitrogen.

[0156] Modification dosage refers to the proportion of inorganic minerals in the mass of the stabilized carbon skeleton during the preparation of mineral-supported carbon skeletons. This dosage is not fixed but is dynamically calculated based on the ammonia nitrogen leaching concentration. Mechanical blending is a process of forcibly and uniformly mixing the stabilized carbon skeleton powder with the inorganic mineral powder weighed according to the calculated dosage through physical stirring, grinding, or shearing.

[0157] Specifically, based on the specific surface area and functional group abundance of the stabilized carbon framework, combined with the initial carbon-nitrogen imbalance, a cation adsorption capacity correction factor is calculated. Then, based on the ammonia nitrogen leaching concentration of the target soil patch, and combined with the cation adsorption capacity correction factor, the incorporation ratio of inorganic minerals is dynamically configured to obtain the modified inorganic mineral dosage. Finally, the weighed inorganic mineral powder and stabilized carbon framework powder are mechanically blended to prepare a mineral-supported carbon framework.

[0158] Step S30 in the method provided in this embodiment of the invention includes:

[0159] The specific surface area of ​​the stabilized carbon skeleton was determined by gas adsorption, and the total amount of surface acidic functional groups of the stabilized carbon skeleton was determined by chemical titration, which was used as the functional group abundance.

[0160] The specific surface area and the carbon retention rate are fused to obtain the effective adsorption area, and the density of active adsorption sites is calculated by combining the functional group abundance.

[0161] The initial adsorption capacity is obtained based on the effective adsorption area and the density of active adsorption sites.

[0162] The initial adsorption capacity and the initial carbon-nitrogen imbalance are fused to obtain the cation adsorption capacity correction factor, wherein the cation adsorption capacity correction factor and the initial carbon-nitrogen imbalance have an inverse relationship.

[0163] In this embodiment, after obtaining the stabilized carbon skeleton powder, two identical samples are obtained. The specific surface area of ​​the first sample is determined using a gas adsorption method. This gas adsorption method involves measuring the amount of nitrogen adsorbed on the solid surface at different relative pressures under liquid nitrogen temperature. The total surface area per unit mass of the sample is calculated using the BET multilayer adsorption theory. Specific surface area is the total surface area per unit mass of the stabilized carbon skeleton, and its value is the ratio of the total surface area of ​​the solid skeleton to the total volume of the porous medium. Therefore, the specific surface area of ​​the stabilized carbon skeleton = total surface area of ​​the solid skeleton / total volume of the porous medium.

[0164] The second sample was analyzed using a chemical titration method to determine the total amount of surface acidic functional groups on the stabilized carbon framework. This chemical titration method specifically refers to the Boehm titration. Solutions of varying alkalinity selectively neutralize oxygen-containing functional groups of different acidities on the carbon material surface. The amount of each functional group consumed is used to infer its content, and the total amount of surface acidic functional groups is obtained by summing these values. This total amount of surface acidic functional groups is used as the functional group abundance, characterizing the chemisorption capacity of the functional groups.

[0165] Secondly, the specific surface area and carbon retention rate are combined to obtain the effective adsorption area, i.e., effective adsorption area = specific surface area / carbon retention rate, which represents the actual specific surface area present in the final stabilized carbon framework product. Then, combined with the functional group abundance, the density of active adsorption sites is calculated, i.e., active adsorption site density = functional group abundance / carbon retention rate, which represents the distribution density of surface chemical activity.

[0166] Next, the initial adsorption capacity is obtained based on the effective adsorption area and the density of active adsorption sites. The initial adsorption capacity is the theoretical maximum adsorption capacity of a unit mass of stabilized carbon skeleton for ammonium nitrogen under ideal conditions, such as a pure water system, no competing ions, suitable pH, and no competing ions. Specifically, the initial adsorption capacity = effective adsorption area × active adsorption site density.

[0167] For example, assume the effective adsorption area is 126 m² / g and the active adsorption site density is 0.012 mmol / m². Assuming each active site can adsorb one ammonium ion, the initial adsorption capacity per unit mass of carbon skeleton is 126 m² / g × 0.012 mmol / m² = 1.512 mmol / g.

[0168] Finally, the initial adsorption capacity and the initial carbon-nitrogen imbalance are fused to obtain the cation adsorption capacity correction factor, which shows an inverse relationship with the initial carbon-nitrogen imbalance. The cation adsorption capacity correction factor = initial adsorption capacity / (1 + initial carbon-nitrogen imbalance). Assuming an initial adsorption capacity of 22.5 mgN / g and an initial carbon-nitrogen imbalance of 4.5, the cation adsorption capacity correction factor would be approximately 22.5 / (1 + 4.5) ≈ 4.1 mgN / g.

[0169] Step S30 in the method provided in this embodiment of the invention further includes:

[0170] The ammonia nitrogen leaching concentration is multiplied by the initial carbon-nitrogen imbalance, and the resulting product is used as the basic ammonium nitrogen load reflecting the soil ammonium nitrogen retention requirement of the target patch.

[0171] Obtain the functional group abundance of the stabilized carbon framework and the cation adsorption capacity correction factor;

[0172] The functional group abundance is multiplied by the cation adsorption capacity correction factor, and the product is used as the adsorption efficiency index of ammonium nitrogen per unit mass of the stabilized carbon framework.

[0173] Based on the basic ammonium nitrogen loading and the adsorption efficiency index, the mineral content baseline is calculated;

[0174] Based on the target repair cycle and the initial carbon-nitrogen imbalance, the dosage correction coefficient determined collaboratively, combined with the mineral dosage base, is used to calculate the modified dosage;

[0175] Based on the carbon retention rate and the carbon mass fraction of the original carbon-rich organic material, the upper limit of the dosage reflecting the carrying capacity of the stabilized carbon framework for inorganic minerals is determined.

[0176] When the modified dosage exceeds the upper limit of the dosage, the adsorption efficiency index is corrected a second time by the cation adsorption capacity correction factor to obtain the corrected adsorption efficiency index.

[0177] The modified dosage is recalculated based on the basic ammonium nitrogen load and the corrected adsorption efficiency index, and compared again with the upper limit of the dosage. The lower of the two values ​​is taken as the final modified dosage.

[0178] In this embodiment, the ammonia nitrogen leaching concentration is first multiplied by the initial carbon-nitrogen imbalance. The resulting product is used as the basic ammonium nitrogen load reflecting the ammonium nitrogen retention requirement of the target patch soil. The basic ammonium nitrogen load = ammonia nitrogen leaching concentration × initial carbon-nitrogen imbalance. For example, assuming the ammonia nitrogen leaching concentration = 45 mg / L and the initial carbon-nitrogen imbalance = 4.5, the basic ammonium nitrogen load = 45 × 4.5 = 202.5 is obtained by multiplying.

[0179] Secondly, based on the calculation method of functional group abundance and cation adsorption capacity correction factor, the functional group abundance and cation adsorption capacity correction factor of the stabilized carbon skeleton are obtained.

[0180] Next, the functional group abundance is multiplied by the cation adsorption capacity correction factor, and the resulting product is used as the adsorption efficiency index of ammonium nitrogen per unit mass of stabilized carbon framework. The adsorption efficiency index of ammonium nitrogen per unit mass of stabilized carbon framework = functional group abundance × cation adsorption capacity correction factor. This represents the overall adsorption capacity characterization in a real environment. The larger the value, the stronger the nitrogen fixation capacity of the carbon framework itself, and the less inorganic minerals need to be added.

[0181] Furthermore, the mineral adsorption base is calculated based on the basic ammonium nitrogen loading and adsorption efficiency index. Wherein, basic ammonium nitrogen loading = ammonia nitrogen leaching concentration × initial carbon-nitrogen imbalance; adsorption efficiency index = functional group abundance × cation adsorption capacity correction factor.

[0182] The mineral content base is the mass ratio of inorganic minerals to the stabilized carbon skeleton calculated based on pure adsorption requirements without considering other correction factors. It reflects the amount of minerals required to balance a unit mass of carbon skeleton. The calculation formula is: Mineral content base = Basic ammonium nitrogen load / Adsorption efficiency index.

[0183] Furthermore, based on the target remediation period and the initial carbon-nitrogen imbalance, a correction coefficient for the dosage is determined collaboratively, and combined with the base mineral dosage, the modified dosage is calculated. The correction coefficient is calculated as: Target remediation period / (Initial carbon-nitrogen imbalance + Target remediation period). This correction coefficient adjusts the mineral dosage to accommodate time constraints.

[0184] The modified content is obtained by multiplying the base mineral content by the content correction factor. The calculation formula is: Modified content = Base mineral content × Content correction factor.

[0185] Furthermore, based on the carbon retention rate and the carbon mass fraction of the original carbon-rich organic material, an upper limit for the dosage reflecting the capacity of the stabilized carbon skeleton to support inorganic minerals is determined. The upper limit is calculated as: upper limit = carbon retention rate × carbon mass fraction of the original carbon-rich organic material. This upper limit reflects the maximum physical capacity of the stabilized carbon skeleton to support inorganic minerals; exceeding this limit will lead to carbon skeleton breakage, uneven mixing, or inability to form particles.

[0186] Furthermore, when the modified dosage exceeds the upper limit, the adsorption efficiency index is corrected a second time by the cation adsorption capacity correction factor. The adsorption efficiency index is obtained by multiplying the cation adsorption capacity correction factor by the adsorption efficiency index, that is, the corrected adsorption efficiency index = adsorption efficiency index × cation adsorption capacity correction factor.

[0187] Finally, the modified dosage was recalculated based on the basic ammonium nitrogen load and the corrected adsorption efficiency index. The recalculated mineral modified dosage base = basic ammonium nitrogen load / corrected adsorption efficiency index. Then, the modified dosage was calculated based on the recalculated mineral modified dosage base. The recalculated modified dosage = recalculated mineral modified dosage base × target remediation cycle / (initial carbon-nitrogen imbalance + target remediation cycle).

[0188] The recalculated modified dosage is compared with the upper limit of dosage, and the lower value of the two is taken as the final modified dosage, that is, the final modified dosage = min(recalculated modified dosage, upper limit of dosage).

[0189] In this embodiment, the effective adsorption area and active adsorption site density are calculated by measuring the specific surface area and functional group abundance. The initial adsorption capacity is obtained by using the effective adsorption area and active adsorption site density. Finally, a correction factor is obtained by integrating the initial carbon-nitrogen imbalance, establishing a transformation from the physicochemical properties of the carbon skeleton to the actual environmental adsorption capacity, which provides a basis for the subsequent dynamic configuration of inorganic mineral doping. Subsequently, the basic ammonium nitrogen load is calculated, and the adsorption efficiency index is calculated based on the functional group abundance and correction factor, providing a scientific input for the mineral doping requirements. Then, the mineral doping baseline is calculated, and the modified doping amount is obtained based on the mineral doping baseline, and the upper limit of the doping amount is determined to determine the final doping amount.

[0190] S40: Using the initial carbon-nitrogen ratio and the carbon retention rate of the stabilized carbon skeleton as constraints, calculate the synergistic effect coefficient of the mineral-supported carbon skeleton and the inorganic nitrogen passivator and determine the final mixing ratio. Perform gradient granulation under humidity conditions that match the moisture content of the target patch soil to obtain porous particles with humidity adaptation and carbon-nitrogen synergistic effect.

[0191] In this embodiment, carbon retention rate is the percentage of the residual total carbon mass in the stabilized carbon skeleton after pre-oxidation treatment to the total carbon mass in the original carbon-rich organic material; inorganic nitrogen passivator is a substance that reduces the bioavailability and migration capacity of excess inorganic nitrogen in the soil through chemical transformation, biological inhibition or precipitation.

[0192] Synergistic effect coefficient is a calculated numerical parameter used to quantify whether the overall control effect of mineral-supported carbon skeleton and inorganic nitrogen passivator on soil inorganic nitrogen when used in combination is better than the sum of the effects of using them individually; final mixing ratio is the mass ratio between mineral-supported carbon skeleton and inorganic nitrogen passivator in the final product; gradient granulation is a process in which the mixture is gradually densified and shaped into granules by applying progressively increasing mechanical pressure under controlled humidity conditions.

[0193] Specifically, the initial carbon-to-nitrogen ratio and the carbon retention rate of the stabilized carbon skeleton are used as constraints to calculate the synergistic effect coefficient between the mineral-supported carbon skeleton and the inorganic nitrogen passivator. The final mixing ratio is then determined based on this coefficient, and the soil moisture content of the target patch is used as the target value for environmental humidity control. After uniformly mixing the mineral-supported carbon skeleton and the inorganic nitrogen passivator at the optimal final mixing ratio, the mixture is extruded under gradually increasing pressure using a gradient granulation device under matched humidity conditions to ultimately obtain porous particles with humidity adaptation and carbon-nitrogen synergistic effect.

[0194] like Figure 2 As shown, step S40 in the method provided in this embodiment of the invention includes:

[0195] Obtain the final modified dosage of the mineral-supported carbon framework and the cation adsorption capacity correction factor;

[0196] The initial carbon-nitrogen ratio and the carbon retention rate are fused to obtain the carbon skeleton stability index, and combined with the final modified doping amount, the potential retention capacity of the mineral-supported carbon skeleton for ammonium nitrogen is obtained.

[0197] The specific surface area and active component content of the inorganic nitrogen passivating agent are obtained, and the corresponding nitrogen passivation efficiency index is calculated. Combined with the potential retention capacity, the synergistic enhancement coefficient is determined.

[0198] The mass ratio of the mineral-supported carbon skeleton to the inorganic nitrogen passivating agent is determined by the synergistic effect coefficient and used as the final mixing ratio.

[0199] The moisture content of the target patch soil is collected, and the mineral-supported carbon skeleton and the inorganic nitrogen passivating agent are mixed according to the final mixing ratio. Then, under humidity conditions that match the moisture content, gradient granulation is carried out with progressively increasing granulation pressure to obtain the humidity-adapted and carbon-nitrogen synergistic porous particles.

[0200] In this embodiment, the final modified dosage of the mineral-supported carbon skeleton and the cation adsorption capacity correction factor are first obtained.

[0201] Secondly, the initial carbon-nitrogen ratio and carbon retention rate are combined to obtain the carbon skeleton stability index, which is calculated as: initial carbon-nitrogen ratio × carbon retention rate. Then, combined with the final modified dosage, the potential retention capacity of the mineral-supported carbon skeleton for ammonium nitrogen is obtained. The potential retention capacity is the expected maximum retention of ammonium nitrogen per unit mass of the mineral-supported carbon skeleton, calculated as: potential retention capacity = carbon skeleton stability index × final modified dosage.

[0202] Furthermore, the specific surface area and active component content of the inorganic nitrogen passivator were obtained, and the corresponding nitrogen passivation efficiency index was calculated. The nitrogen passivation efficiency index = specific surface area of ​​the inorganic nitrogen passivator × active component content of the inorganic nitrogen passivator. This index characterizes the total ammonium nitrogen treatment capacity of the passivator under the combined action of physical adsorption and chemical fixation. Subsequently, combined with the potential retention capacity, the synergistic effect coefficient was determined. The synergistic effect coefficient = potential retention capacity / nitrogen passivation efficiency index. When the synergistic effect coefficient > 1, it indicates that the combined use of the two has a positive synergistic effect; when the synergistic effect coefficient = 1, there is no synergistic effect; when the synergistic effect coefficient < 1, it indicates that the combined use of the two has an antagonistic effect.

[0203] Furthermore, the mass ratio of the mineral-supported carbon skeleton to the inorganic nitrogen passivator is determined using the synergistic effect coefficient, and this ratio is used as the final blending ratio. The final blending ratio is the mass ratio between the mineral-supported carbon skeleton and the inorganic nitrogen passivator, typically expressed as the mass of the carbon skeleton. This ratio is directly determined by the synergistic effect coefficient.

[0204] Specifically, the sum of the numerical value 1 and the synergistic effect coefficient is used as the total mass fraction; then the synergistic effect coefficient is divided by the total mass fraction, and the resulting ratio is used as the mass percentage of the mineral-supported carbon skeleton in the final blending ratio; the difference between the numerical value 1 and the mass percentage of the mineral-supported carbon skeleton is used as the mass percentage of the inorganic nitrogen passivator in the final blending ratio.

[0205] Next, calculate the ratio of the mass percentage of the mineral-supported carbon skeleton to the mass percentage of the inorganic nitrogen passivator, and use this as the final blending ratio. The final blending ratio is mineral-supported carbon skeleton:inorganic nitrogen passivator.

[0206] Finally, the soil moisture content of the target patch was collected. Soil moisture content is the percentage of water mass in the surface soil of the target patch relative to the dry soil mass, determined using the oven-drying method. This parameter affects the plasticity of the material and the stability of the particles during granulation.

[0207] Subsequently, the mineral-supported carbon skeleton and the inorganic nitrogen passivator were mixed according to the final mixing ratio to obtain humidity conditions that match the moisture content. The relative humidity of the granulation environment was adjusted to a level corresponding to the soil moisture content. The mixture was then subjected to gradient granulation using progressively increasing granulation pressure. After extrusion molding, porous particles with a gradient distribution of density / porosity from the core to the shell, suitable humidity, and carbon-nitrogen synergy were formed.

[0208] The method provided in this embodiment of the invention involves gradient granulation under humidity conditions matching the moisture content, using progressively increasing granulation pressure to obtain the humidity-adapted and carbon-nitrogen synergistic porous particles, including:

[0209] The soil moisture content of the target patch is collected, and the humidity of the granulation environment is adjusted to be within ±3% of the moisture content.

[0210] After the mineral-supported carbon skeleton and the inorganic nitrogen passivator are mixed evenly according to the final mixing ratio, the mixture is placed in a granulation environment to allow it to stand and adjust the humidity so that the moisture content of the mixture reaches equilibrium with the ambient humidity.

[0211] The conditioned mixture is extruded and molded under an initial granulation pressure to obtain a particle core, wherein the initial granulation pressure is determined by the carbon retention rate, and the lower the carbon retention rate, the higher the initial granulation pressure.

[0212] Based on the particle core, a multi-stage pressurization densification process is performed with progressively increasing granulation pressure, wherein the increment of each pressure stage is determined by the synergistic enhancement coefficient and the carbon retention rate.

[0213] After multi-stage pressurization, the particles are left to stand and solidify in the granulation environment to obtain the humidity-adapted and carbon-nitrogen synergistic porous particles.

[0214] In this embodiment, firstly, the moisture content of the target soil patch is calculated after drying to constant weight using the 105℃ drying method. Then, the relative humidity of the granulation environment is controlled within ±3% of the target soil moisture content. For example, if the soil moisture content is 65%, the ambient humidity should be adjusted to 62%–68% RH, monitored in real time, until the humidity stabilizes within the 62%–68% range and is maintained for at least 30 minutes.

[0215] Next, the mineral-supported carbon skeleton and inorganic nitrogen passivator powder, which are mixed according to the final mixing ratio, are placed on a tray and placed in a granulation environment with regulated humidity. The tray is kept still so that the moisture on the surface of the material particles and in the capillary channels can exchange with the water vapor in the air until the overall moisture content of the material is consistent with the equilibrium moisture content corresponding to the ambient humidity, that is, the moisture content of the mixture is in equilibrium with the ambient humidity.

[0216] Furthermore, the conditioned mixture is extruded under an initial granulation pressure to obtain particle cores. The initial granulation pressure is the mechanical pressure applied during the first extrusion. This pressure is determined by the carbon retention rate; the lower the carbon retention rate, the higher the initial granulation pressure. The obtained particle cores are the primary particles formed in the first stage of the gradient granulation process. These cores are relatively loose and have high porosity, serving as the basis for subsequent densification treatment.

[0217] Furthermore, based on the particle core, a multi-stage pressurization densification process is performed using progressively increasing granulation pressure. That is, without changing the mold or reloading the material, the pressure is gradually increased and applied again, causing the particles to gradually become denser from the inside out. After each stage of pressurization, the outer layer density of the particles increases, while the core density changes less, thus forming a density gradient. Ultimately, this results in a hierarchical porous structure within the porous particles, with pore size decreasing from the inside out.

[0218] The increment is the amount by which the pressure increases from the previous level. The increment of pressure at each level is determined by the synergistic effect coefficient and the carbon retention rate. For example, increment = previous level pressure × (synergistic effect coefficient / 2) × (1 - carbon retention rate). The larger the synergistic effect coefficient, the stronger the adsorption-passivation synergy and the more rapid the pressure increase; the lower the carbon retention rate, the more fragile the carbon skeleton and the more gradual the pressure increase.

[0219] Finally, after multi-stage pressurization, the particles are left to stand under the same humidity conditions as the granulation environment for a period of time. This allows the residual stress inside the particles to gradually release, and the moisture to be further evenly distributed. The particles then reach their final mechanical strength and structural stability, completing the particle solidification process. The resulting solidified particles are porous materials with suitable humidity and synergistic carbon-nitrogen interaction.

[0220] In this embodiment, the potential retention capacity of the mineral-supported carbon skeleton is combined with the nitrogen passivation efficiency index of the inorganic nitrogen passivator to determine the synergistic effect of their combined use and to determine the final mixing ratio, which serves as the input parameter for subsequent pore size tailoring. The dynamically determined final mixing ratio ensures that the soil conditioner can exert its optimal functional synergy on different patches, achieving dynamic adaptation of the compounding ratio. By precisely adjusting the humidity of the granulation environment to match the target soil moisture content, the cracking and disintegration problems caused by drastic humidity changes in wetlands are solved, improving the physical stability of the particles in the target soil. A gradient granulation process driven by carbon retention rate and synergistic effect coefficient is established to form a denser shell to delay release, ultimately obtaining porous particles and improving the applicability and long-term remediation effect of the soil conditioner.

[0221] S50: Based on the synergistic effect coefficient, the internal pore size distribution of the porous particles is partitioned and gradient-tailed, and the tolerance matching correction is performed in combination with the initial carbon-nitrogen imbalance to obtain the final structure-function integrated targeted soil conditioner.

[0222] In this embodiment, the internal pore size distribution refers to the proportion of the volume of pores of different sizes and their spatial arrangement characteristics within the solid skeleton of porous particles; the partitioned gradient cutting is a process that sets a gradient range of pore size for different regions of the particles from the inside to the outside along the radial direction according to the target functional requirements, and precisely controls it through physical or chemical means.

[0223] Tolerance matching correction is a process in which the difference between the theoretically optimal pore sizes calculated from the initial carbon-nitrogen imbalance exceeds the allowable tolerance threshold, and the pore sizes of each internal layer are adjusted in reverse for compensatory correction. The structure-function integrated targeted soil conditioner is the final product that can be targeted to specific carbon-nitrogen imbalance environments.

[0224] Specifically, based on the synergistic effect coefficient, the internal pore size distribution of porous particles is partitioned and gradient-tailed, setting a gradient pore size range for different regions of the particles from the inside to the outside along the radial direction. Subsequently, in conjunction with the initial carbon-nitrogen imbalance, tolerance matching correction is performed by adjusting the pore size of each internal layer in reverse, and the treated gradient pore structure is fixed to obtain the final structure-function integrated targeted soil conditioner.

[0225] Step S50 in the method provided in this embodiment of the invention includes:

[0226] When the synergistic effect coefficient is greater than 1, the internal pore size of the porous particles is divided into three regions radially from the inside to the outside: a dense core layer, a transition buffer layer, and a porous outer shell layer.

[0227] When the synergistic effect coefficient is not greater than 1, the internal pore size of the porous particles is divided into three regions from the inside to the outside along the radial direction: a porous core layer, a transition buffer layer, and a dense outer shell layer.

[0228] Based on the synergistic effect coefficient, the aperture range and layer thickness ratio of each region are determined. The greater the deviation of the synergistic effect coefficient from 1, the more significant the aperture difference between adjacent regions.

[0229] The initial carbon-nitrogen imbalance is obtained, and the initial carbon-nitrogen imbalance is compared with the target pore size of the outermost region of the porous particles to calculate the tolerance deviation.

[0230] Calculate the difference between the tolerance deviation magnitude and the tolerance threshold, and determine the scaling correction magnitude based on the difference and the initial carbon-nitrogen imbalance, wherein the tolerance threshold is the allowable upper limit of deviation jointly determined by the carbon retention rate and the target repair cycle;

[0231] The target pore size of the outermost region of the porous particles is scaled and corrected using the scaling correction range to obtain the corrected outermost pore size, and the difference between the outermost pore size before and after correction is calculated as the pore size correction amount.

[0232] Obtain the ratio of the kernel layer and the transition layer to the thickness of the layer, and allocate the aperture correction amount to the kernel layer and the transition layer according to the ratio.

[0233] When the outermost aperture shrinks, the allocated correction amount is superimposed on the core layer aperture and the transition layer aperture accordingly.

[0234] When the outermost pore size expands, the allocated correction amount is subtracted from the corresponding core layer pore size and the transition layer pore size to keep the total pore volume inside the porous particles constant.

[0235] The particles with modified pore size are thermally stabilized in an inert atmosphere to obtain the structure-function integrated targeted soil conditioner.

[0236] In this embodiment, a layered mode is first selected based on the synergistic effect coefficient. When the synergistic effect coefficient is greater than 1, the synergistic effect is strong. In this mode, the innermost layer is dense to store the passivating agent and delay its release, while the outermost layer is porous to rapidly adsorb ammonium nitrogen from the environment.

[0237] The internal pore size of porous particles is divided into three regions from the inside out along the radial direction from the particle center to the particle surface: a dense core layer, a transition buffer layer, and a porous outer shell layer. The dense core layer, located in the center of the particle, has smaller pore sizes (e.g., <10 nm), higher density, and lower porosity. It is primarily used to store passivating agents and control their slow release.

[0238] The transition buffer layer is located between the core and the shell, with a medium pore size, such as 10-50 nm, and a gradually changing density. It is used to alleviate internal stress caused by the difference in thermal expansion coefficients. The porous shell layer has a larger pore size, such as >50 nm, a lower density, and a higher porosity. It is used to rapidly adsorb ammonium nitrogen in the soil solution.

[0239] Secondly, the synergistic effect is weak when the synergistic coefficient is no greater than 1. The porous particles are divided radially from the inside out into three regions: a porous core layer, a transition buffer layer, and a dense outer shell layer. In this model, the porous core layer facilitates rapid adsorption, while the dense outer shell layer prevents the re-release of adsorbed nitrogen or limits the excessive loss of passivating agents. Specifically, the porous core layer has large pore sizes and low density for rapid adsorption, while the dense outer shell layer has small pore sizes and high density for physical isolation or delaying the release of internal substances.

[0240] Furthermore, based on the synergistic effect coefficient, the pore size range and layer thickness ratio of each region are determined. The pore size range is a preset range of pore diameter within each layer, typically measured in nanometers. For example, the dense layer has a pore size of 2–10 nm, the transition layer 10–50 nm, and the porous layer 50–200 nm. The layer thickness ratio is the percentage of each region's thickness relative to the total particle radius. For example, the dense core accounts for 30%, the transition layer 20%, and the porous shell 50%.

[0241] The greater the deviation of the synergistic effect coefficient from 1, the more significant the difference in pore size between adjacent regions, and the more extreme the corresponding layer thickness ratio.

[0242] Furthermore, the initial carbon-nitrogen imbalance is obtained, and then compared with the target pore size of the outermost region of the porous particles to calculate the tolerance deviation. The tolerance deviation reflects the difference between the theoretical tolerance deviation and the pore size that can be stably prepared by the actual process. Specifically, the tolerance deviation is calculated as: |(Target pore size of the outermost region of the porous particles − Initial carbon-nitrogen imbalance × Reference pore size) / (Initial carbon-nitrogen imbalance × Reference pore size)|. The reference pore size is the pore size value of the outermost region of the porous particles when the synergistic effect coefficient equals 1.

[0243] Furthermore, the difference between the tolerance deviation and the tolerance threshold is calculated. Based on this difference and the initial carbon-nitrogen imbalance, the scaling correction magnitude is determined, whereby the scaling correction magnitude is used to adjust the pore size correction. When the tolerance deviation exceeds the tolerance threshold, a correction is required based on the scaling correction magnitude: Scaling correction magnitude = (Tolerance deviation - Tolerance threshold) × Initial carbon-nitrogen imbalance.

[0244] The tolerance threshold is the upper limit of allowable deviation determined jointly by the carbon retention rate and the target repair cycle. The tolerance threshold represents the economics of process control. The higher the carbon retention rate and the shorter the target repair cycle, the smaller the tolerance threshold, requiring greater precision; the lower the carbon retention rate and the longer the target repair cycle, the larger the tolerance threshold, allowing for greater deviation. Its calculation formula is: Tolerance threshold = Carbon retention rate × [Target repair cycle / (Carbon retention rate + Target repair cycle)].

[0245] Furthermore, the target pore size of the outermost region of the porous particles is scaled and corrected by the scaling correction range to obtain the corrected outermost pore size. If the original outermost target pore size is greater than the initial carbon-nitrogen imbalance multiplied by the reference pore size, then the corrected outermost pore size = (original outermost target pore size / (1 + scaling correction range)), and is reduced; if the original outermost target pore size is less than the initial carbon-nitrogen imbalance multiplied by the reference pore size, then the corrected outermost pore size = original outermost target pore size × (1 + scaling correction range), and is enlarged.

[0246] Subsequently, after scaling and correcting the outermost target aperture, the difference between the outermost aperture before and after correction is calculated as the aperture correction amount, which is the absolute difference between the outermost target aperture before and after correction.

[0247] Furthermore, obtain the proportion of the thickness occupied by the kernel layer and the transition layer, where the proportion of the thickness occupied by the kernel layer = kernel layer thickness / (kernel layer thickness + transition layer thickness); similarly, the proportion of the thickness occupied by the transition layer = transition layer thickness / (kernel layer thickness + transition layer thickness).

[0248] The aperture correction amount is allocated according to the proportional values ​​corresponding to the core layer and the transition layer. Specifically, the aperture correction amount for the core layer = aperture correction amount × the proportion of the core layer to the layer thickness; the aperture correction amount for the transition layer = aperture correction amount × the proportion of the transition layer to the layer thickness.

[0249] For example, suppose the layer thickness ratio is: core layer 50%, transition layer 50%. Therefore, the thickness ratio of the core layer to the transition layer is 1:1. Aperture correction amount = 14nm. With a 1:1 allocation, the core layer accounts for 7nm, and the transition layer accounts for 7nm.

[0250] Furthermore, when the outermost pore size shrinks, the interior must become more porous to compensate for the pressure. That is, the corrected outermost pore size is smaller than the original target pore size. The allocated correction amount is then correspondingly added to the inner core pore size and the transition layer pore size to compensate for the reduction in outer layer volume. Therefore, the allocated correction amount for the inner core layer = the original target innermost pore size + the inner core pore size correction amount; the allocated correction amount for the transition layer = the original target innermost pore size + the transition layer pore size correction amount.

[0251] Furthermore, when the outermost pore size expands, the interior must become denser to compensate for the pressure. That is, the corrected outermost pore size is larger than the original target pore size. The allocated correction is then subtracted from the core layer pore size and the transition layer pore size to maintain volume balance, ensuring the total pore volume within the porous particles remains constant. Therefore, the allocated correction for the core layer = original target pore size of the innermost layer - core layer pore size correction; the allocated correction for the transition layer = original target pore size of the innermost layer - transition layer pore size correction.

[0252] Finally, the pore-size modified particles undergo thermal stabilization treatment in an inert atmosphere. This involves heating the particles to a specific temperature (e.g., 200–400°C) in an inert atmosphere and holding them there for a certain time (e.g., 1–3 hours), followed by slow cooling, to obtain a structure-function integrated targeted soil conditioner. The treated particles change color from grayish-brown to blackish-gray, exhibit significantly improved mechanical strength, and partially transform surface functional groups into a more stable aromatic structure. The inert atmosphere is a gaseous environment containing no oxygen or with extremely low oxygen concentration, which prevents the carbon skeleton from oxidizing and burning at high temperatures.

[0253] In this embodiment, a radial gradient partitioning design based on the synergistic effect coefficient determines the type of internal and external structure of the particles, achieving spatial synergy between adsorption and passivation functions and avoiding mutual inhibition between the two. Subsequently, a quantitative relationship is established between the deviation of the pore size range and the layer thickness ratio from the synergistic effect coefficient. Through this relationship, synergistic effect is achieved, reducing unnecessary process complexity. Tolerance matching correction is then performed by scaling the outermost target pore size and proportionally allocating the inner pore size. The scaling correction range is then determined by the tolerance deviation and the initial carbon-nitrogen imbalance, adjusting the product stability. Finally, the gradient pore structure is fixed by inert atmosphere thermal stabilization treatment, extending the effective action period of the modifier and ensuring the durability of the on-site repair effect.

[0254] The embodiments of this application, through the above specific implementation methods, achieve the following technical effects:

[0255] In this embodiment, a highly operable, repeatable baseline parameter acquisition scheme that eliminates environmental heterogeneity interference is first provided for the preparation method by limiting the sampling timing, standardizing the analysis method, and using the five-point sampling method.

[0256] Secondly, through controllable pre-oxidation treatment and carbon retention rate feedback adjustment, highly active and easily oxidizable organic carbon components are removed in a targeted manner to prepare a stable carbon framework with low biodegradability, avoiding the induced mineralization effect caused by the addition of fresh organic matter and improving the stability of exogenous organic carbon. The basic oxidation intensity is dynamically configured by the ratio of the target remediation cycle to the initial carbon-nitrogen imbalance, and the pre-oxidation process can be adaptively adjusted according to the remediation urgency of different patches by correlating the lower limit of carbon yield with the target remediation cycle. By simultaneously monitoring the proportion of easily oxidizable organic carbon and carbon retention rate, a constraint and closed-loop optimization mechanism for the degree of stabilization and the amount of carbon preserved is established. Finally, through real-time monitoring, endpoint verification, and feedback, the preparation method can automatically adapt to batch differences in raw materials and environmental fluctuations, improving the robustness and repeatability of the process.

[0257] Next, by measuring the specific surface area and functional group abundance, the effective adsorption area and active adsorption site density were calculated. The initial adsorption capacity was obtained using the effective adsorption area and active adsorption site density. Finally, a correction factor was obtained by integrating the initial carbon-nitrogen imbalance, establishing a transformation from the physicochemical properties of the carbon skeleton to actual environmental adsorption capacity, providing a basis for the subsequent dynamic configuration of inorganic mineral dosage. Subsequently, by calculating the basic ammonium nitrogen load, the adsorption efficiency index was calculated based on the functional group abundance and correction factor, providing a scientific input for the mineral dosage requirements. Then, the mineral dosage baseline was calculated, and based on this baseline, the modified dosage was obtained, and the upper limit of the dosage was determined, thus determining the final dosage.

[0258] Furthermore, the potential retention capacity of the mineral-supported carbon skeleton was combined with the nitrogen passivation efficiency index of the inorganic nitrogen passivator to determine the synergistic effect of their combined use and to determine the final mixing ratio, which served as the input parameter for subsequent pore size tailoring. Through dynamically determined final mixing ratios, the soil conditioner was able to exert its optimal functional synergy on different patches, achieving dynamic adaptation of the compounding ratio. By precisely adjusting the humidity of the granulation environment to match the target soil moisture content, the cracking and disintegration problems caused by drastic humidity changes in wetlands were solved, improving the physical stability of the particles in the target soil. A gradient granulation process driven by carbon retention rate and synergistic coefficient was established to form a denser shell to delay release, ultimately obtaining porous particles and improving the applicability and long-term remediation effect of the soil conditioner.

[0259] Ultimately, based on the radial gradient partitioning design using the synergistic effect coefficient, the type of internal and external structure of the particles is determined to achieve spatial synergy between adsorption and passivation functions, avoiding mutual inhibition between the two. Subsequently, a quantitative relationship is established between the deviation of the pore size range and layer thickness ratio from the synergistic effect coefficient. Through this relationship, synergistic effect is achieved, reducing unnecessary process complexity. Tolerance matching correction is then performed by scaling the outermost target pore size and proportionally distributing the inner pore size. The scaling correction magnitude is then determined by the tolerance deviation and the initial carbon-nitrogen imbalance, adjusting product stability. Finally, the gradient pore structure is fixed through inert atmosphere thermal stabilization treatment, extending the effective action period of the modifier and ensuring the durability of the on-site repair effect.

Claims

1. A method for preparing a soil conditioner to improve the stability of organic carbon in Poyang Lake wetlands, characterized in that, The method includes: Obtain raw carbon-rich organic materials, determine the corresponding initial carbon-nitrogen ratio and the proportion of easily oxidizable organic carbon, and collect the initial carbon-nitrogen imbalance and ammonia nitrogen leaching concentration of the target patch soil. Based on the initial carbon-nitrogen imbalance and the target repair cycle, the carbon skeleton pre-oxidation intensity is configured, and the original carbon-rich organic material is subjected to pre-oxidation treatment to obtain a stabilized carbon skeleton. Based on the specific surface area and functional group abundance of the stabilized carbon skeleton, the cation adsorption capacity correction factor is calculated, and combined with the ammonia nitrogen leaching concentration, the modification dosage of inorganic minerals is dynamically configured, and a mineral-supported carbon skeleton is obtained through mechanical blending. Using the initial carbon-nitrogen ratio and the carbon retention rate of the stabilized carbon skeleton as constraints, the synergistic effect coefficient of the mineral-supported carbon skeleton and the inorganic nitrogen passivator is calculated and the final mixing ratio is determined. Gradient granulation is carried out under humidity conditions that match the moisture content of the target patch soil to obtain porous particles with humidity adaptability and carbon-nitrogen synergistic effect. Based on the synergistic effect coefficient, the internal pore size distribution of the porous particles is partitioned and gradient-tailed, and the tolerance matching correction is performed in combination with the initial carbon-nitrogen imbalance to obtain the final structure-function integrated targeted soil conditioner.

2. The method for preparing a soil conditioner to improve the organic carbon stability of Poyang Lake wetlands according to claim 1, characterized in that, Obtain raw carbon-rich organic material, determine the corresponding initial carbon-to-nitrogen ratio and the proportion of easily oxidizable organic carbon, and collect the initial carbon-to-nitrogen imbalance and ammonia nitrogen leaching concentration of the target patch soil, including: Raw carbon-rich organic materials were collected from the shoreline of the bird gathering area in Poyang Lake wetland. After drying and pulverizing, the total carbon and total nitrogen content were determined using an elemental analyzer, and the initial carbon-nitrogen ratio was calculated. The original carbon-rich organic material was oxidized by potassium dichromate-sulfuric acid external heating method. Easily oxidizable carbon was extracted with 333-667 mmol / L potassium permanganate solution. The percentage of oxidized carbon to total carbon content was determined as the percentage of easily oxidizable organic carbon. One month before and after the seasonal peak of bird droppings, topsoil samples were collected from the target patches using a five-point sampling method. After being mixed evenly, the total inorganic nitrogen and total organic carbon content of the soil were measured. The deviation of the ratio of the total inorganic nitrogen to the total organic carbon from the corresponding ratio in the reference area where there is no bird activity in the same region is taken as the initial carbon-nitrogen imbalance. Soil pore water from the target patch was collected, filtered through a 0.22–0.65 μm filter membrane, and the concentration of ammonium nitrogen in the filtrate was determined by Nessler's reagent colorimetric method, which was used as the ammonia nitrogen leaching concentration.

3. The method for preparing a soil conditioner to improve the stability of organic carbon in Poyang Lake wetlands according to claim 1, characterized in that, Based on the initial carbon-nitrogen imbalance and the target remediation cycle, the carbon framework pre-oxidation intensity is configured, and the original carbon-rich organic material is subjected to pre-oxidation treatment to obtain a stabilized carbon framework, including: The ratio of the initial carbon-nitrogen imbalance to the target repair cycle is used as the base oxidation intensity, and the original carbon-rich organic material is pre-oxidized using the base oxidation intensity. During the processing, the proportion of easily oxidizable organic carbon in the original carbon-rich organic material is monitored. When the proportion of easily oxidizable organic carbon drops to a stable range that matches the initial carbon-nitrogen imbalance, the oxidation reaction is terminated. The material after oxidation termination is washed with deionized water until neutral, vacuum dried at 45-65°C to constant weight, pulverized and sieved, and powder with a particle size of less than 0.25 mm is collected as the stabilized carbon skeleton. The stabilized carbon skeleton was subjected to elemental analysis to determine the carbon content after stabilization. The ratio of the carbon content after stabilization to the total carbon content before oxidation was taken as the carbon retention rate. When the carbon retention rate is lower than the lower limit of carbon yield that matches the target repair cycle, the basic oxidation intensity is reduced by an amount appropriate to the deviation of the carbon retention rate, and the pre-oxidation treatment is repeated until the carbon retention rate reaches the lower limit of carbon yield and the proportion of easily oxidizable organic carbon drops to a stable range that matches the initial carbon-nitrogen imbalance.

4. The method for preparing a soil conditioner to improve the stability of organic carbon in Poyang Lake wetlands according to claim 3, characterized in that, During the processing, the proportion of easily oxidizable organic carbon in the original carbon-rich organic material is monitored. When the proportion of easily oxidizable organic carbon drops to a stable range that matches the initial carbon-nitrogen imbalance, the oxidation reaction is terminated, including: Starting from the beginning of the pre-oxidation treatment, a sample of the original carbon-rich organic material was taken every 30 minutes. The easily oxidizable carbon of the sample was extracted using the potassium dichromate-sulfuric acid external heating method with 333-667 mmol / L potassium permanganate solution, and the proportion of easily oxidizable organic carbon in the sample was determined. Based on the initial carbon-nitrogen imbalance, the target repair cycle, and the proportion of easily oxidizable organic carbon, the oxidation termination threshold is determined. Based on the initial carbon-nitrogen imbalance and the target repair cycle, a lower limit reference value for the stable range is jointly determined; When the proportion of easily oxidizable organic carbon in the sample drops below the oxidation termination threshold for the first time, restore the original oxidation conditions and continue treatment for 5 to 8 minutes. Take a sample again for measurement. If the proportion of easily oxidizable organic carbon measured again still does not exceed the oxidation termination threshold, the reaction endpoint is confirmed to have been reached. If the percentage of easily oxidizable organic carbon measured again rebounds to above the oxidation termination threshold, the oxidation process continues and sampling is repeated until the percentage of easily oxidizable organic carbon measured in two consecutive measurements is not higher than the oxidation termination threshold and not lower than the lower limit reference value, at which point the oxidation reaction is terminated.

5. The method for preparing a soil conditioner to improve the stability of organic carbon in Poyang Lake wetlands according to claim 4, characterized in that, Based on the initial carbon-nitrogen imbalance and the target repair cycle, a lower limit reference value for the stability range is jointly determined, including: The ratio of the initial carbon-nitrogen imbalance to the target repair cycle is used as the time pressure coefficient; The initial easily oxidizable organic carbon percentage of the original carbon-rich organic material before pre-oxidation treatment is collected, and combined with the time-pressure coefficient, a deep oxidation baseline value is obtained. Based on the target repair cycle and the initial carbon-nitrogen imbalance, a repair urgency factor is calculated, wherein the repair urgency factor is inversely proportional to the target repair cycle and directly proportional to the initial carbon-nitrogen imbalance; Based on the aforementioned deep oxidation baseline value and the aforementioned repair urgency factor, a lower limit correction weight is determined collaboratively. Based on the lower limit correction weight, the oxidation termination threshold is scaled and adjusted to obtain the lower limit reference value of the stable range.

6. The method for preparing a soil conditioner to improve the stability of organic carbon in Poyang Lake wetlands according to claim 1, characterized in that, Based on the specific surface area and functional group abundance of the stabilized carbon framework, the cation adsorption capacity correction factor is calculated, including: The specific surface area of ​​the stabilized carbon skeleton was determined by gas adsorption, and the total amount of surface acidic functional groups of the stabilized carbon skeleton was determined by chemical titration, which was used as the functional group abundance. The specific surface area and the carbon retention rate are fused to obtain the effective adsorption area, and the density of active adsorption sites is calculated by combining the functional group abundance. The initial adsorption capacity is obtained based on the effective adsorption area and the density of active adsorption sites. The initial adsorption capacity and the initial carbon-nitrogen imbalance are fused to obtain the cation adsorption capacity correction factor, wherein the cation adsorption capacity correction factor and the initial carbon-nitrogen imbalance have an inverse relationship.

7. The method for preparing a soil conditioner to improve the organic carbon stability of Poyang Lake wetlands according to claim 1, characterized in that, Based on the aforementioned ammonia nitrogen leaching concentration, the modification dosage of inorganic minerals is dynamically configured, including: The ammonia nitrogen leaching concentration is multiplied by the initial carbon-nitrogen imbalance, and the resulting product is used as the basic ammonium nitrogen load reflecting the soil ammonium nitrogen retention requirement of the target patch. Obtain the functional group abundance of the stabilized carbon framework and the cation adsorption capacity correction factor; The functional group abundance is multiplied by the cation adsorption capacity correction factor, and the product is used as the adsorption efficiency index of ammonium nitrogen per unit mass of the stabilized carbon framework. Based on the basic ammonium nitrogen loading and the adsorption efficiency index, the mineral content baseline is calculated; Based on the target repair cycle and the initial carbon-nitrogen imbalance, the dosage correction coefficient determined collaboratively, combined with the mineral dosage base, is used to calculate the modified dosage; Based on the carbon retention rate and the carbon mass fraction of the original carbon-rich organic material, the upper limit of the dosage reflecting the carrying capacity of the stabilized carbon framework for inorganic minerals is determined. When the modified dosage exceeds the upper limit of the dosage, the adsorption efficiency index is corrected a second time by the cation adsorption capacity correction factor to obtain the corrected adsorption efficiency index. The modified dosage is recalculated based on the basic ammonium nitrogen load and the corrected adsorption efficiency index, and compared again with the upper limit of the dosage. The lower of the two values ​​is taken as the final modified dosage.

8. The method for preparing a soil conditioner to improve the organic carbon stability of Poyang Lake wetlands according to claim 1, characterized in that, Constrained by the initial carbon-nitrogen ratio and the carbon retention rate of the stabilized carbon skeleton, the synergistic effect coefficient of the mineral-supported carbon skeleton and the inorganic nitrogen passivator is calculated, and the final mixing ratio is determined. Gradient granulation is then performed under humidity conditions matching the moisture content of the target patch soil to obtain porous particles with humidity adaptability and carbon-nitrogen synergistic effect, including: Obtain the final modified dosage of the mineral-supported carbon framework and the cation adsorption capacity correction factor; The initial carbon-nitrogen ratio and the carbon retention rate are fused to obtain the carbon skeleton stability index, and combined with the final modified doping amount, the potential retention capacity of the mineral-supported carbon skeleton for ammonium nitrogen is obtained. The specific surface area and active component content of the inorganic nitrogen passivating agent are obtained, and the corresponding nitrogen passivation efficiency index is calculated. Combined with the potential retention capacity, the synergistic enhancement coefficient is determined. The mass ratio of the mineral-supported carbon skeleton to the inorganic nitrogen passivating agent is determined by the synergistic effect coefficient and used as the final mixing ratio. The moisture content of the target patch soil is collected, and the mineral-supported carbon skeleton and the inorganic nitrogen passivating agent are mixed according to the final mixing ratio. Then, under humidity conditions that match the moisture content, gradient granulation is carried out with progressively increasing granulation pressure to obtain the humidity-adapted and carbon-nitrogen synergistic porous particles.

9. A method for preparing a soil conditioner to improve the stability of organic carbon in Poyang Lake wetlands according to claim 8, characterized in that, Gradient granulation is performed under humidity conditions matching the moisture content, with progressively increasing granulation pressure, to obtain the humidity-adapted and carbon-nitrogen synergistic porous particles, comprising: The soil moisture content of the target patch is collected, and the humidity of the granulation environment is adjusted to be within ±3% of the moisture content. After the mineral-supported carbon skeleton and the inorganic nitrogen passivator are mixed evenly according to the final mixing ratio, the mixture is placed in a granulation environment to allow it to stand and adjust the humidity so that the moisture content of the mixture reaches equilibrium with the ambient humidity. The conditioned mixture is extruded and molded under an initial granulation pressure to obtain a particle core, wherein the initial granulation pressure is determined by the carbon retention rate, and the lower the carbon retention rate, the higher the initial granulation pressure. Based on the particle core, a multi-stage pressurization densification process is performed with progressively increasing granulation pressure, wherein the increment of each pressure stage is determined by the synergistic enhancement coefficient and the carbon retention rate. After multi-stage pressurization, the particles are left to stand and solidify in the granulation environment to obtain the humidity-adapted and carbon-nitrogen synergistic porous particles.

10. A method for preparing a soil conditioner to improve the stability of organic carbon in Poyang Lake wetlands according to claim 1, characterized in that, Based on the synergistic effect coefficient, the internal pore size distribution of the porous particles is partitioned and gradient-tailed, and tolerance matching correction is performed in conjunction with the initial carbon-nitrogen imbalance to obtain the final structure-function integrated targeted soil conditioner, including: When the synergistic effect coefficient is greater than 1, the internal pore size of the porous particles is divided into three regions radially from the inside to the outside: a dense core layer, a transition buffer layer, and a porous outer shell layer. When the synergistic effect coefficient is not greater than 1, the internal pore size of the porous particles is divided into three regions from the inside to the outside along the radial direction: a porous core layer, a transition buffer layer, and a dense outer shell layer. Based on the synergistic effect coefficient, the aperture range and layer thickness ratio of each region are determined. The greater the deviation of the synergistic effect coefficient from 1, the more significant the aperture difference between adjacent regions. The initial carbon-nitrogen imbalance is obtained, and the initial carbon-nitrogen imbalance is compared with the target pore size of the outermost region of the porous particles to calculate the tolerance deviation. Calculate the difference between the tolerance deviation magnitude and the tolerance threshold, and determine the scaling correction magnitude based on the difference and the initial carbon-nitrogen imbalance, wherein the tolerance threshold is the allowable upper limit of deviation jointly determined by the carbon retention rate and the target repair cycle; The target pore size of the outermost region of the porous particles is scaled and corrected using the scaling correction range to obtain the corrected outermost pore size, and the difference between the outermost pore size before and after correction is calculated as the pore size correction amount. Obtain the ratio of the kernel layer and the transition layer to the thickness of the layer, and allocate the aperture correction amount to the kernel layer and the transition layer according to the ratio. When the outermost aperture shrinks, the allocated correction amount is superimposed on the core layer aperture and the transition layer aperture accordingly. When the outermost pore size expands, the allocated correction amount is subtracted from the corresponding core layer pore size and the transition layer pore size to keep the total pore volume inside the porous particles constant. The particles with modified pore size are thermally stabilized in an inert atmosphere to obtain the structure-function integrated targeted soil conditioner.

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