Spray-seeding ecological restoration method for silicate mineral weathering alkali-induced rock slope

Abstract

The invention relates to the technical field of spray-seeding, and discloses a silicate mineral weathering alkali-induced rock slope spray-seeding ecological restoration method which comprises the following steps: cleaning and leveling an alkaline bedrock slope containing silicate minerals; uniformly spraying a phosphoric acid solution on the surface of the bedrock slope, and then laying a micro covering film to form a neutralization layer; spraying a mixture of sulfur powder and leaf mold on the surface of the neutralization layer to form a slow release layer; borrowed soil spray seeding is performed on the surface of the slow release layer, and herbaceous plant seeds are mixed in borrowed soil. According to the method, a phosphoric acid solution is adopted as a neutralization layer material, and the sulfur powder and the leaf mold are adopted as slow-release layer materials, so that the alkaline environment of the slope body can be quickly improved through the synergistic effect of the neutralization layer and the slow-release layer when the ecological restoration is performed on the alkaline environment slope body, and the stability of the acid-alkali environment of the slope body can be maintained for more than one year. The construction technology is basically similar to a traditional soil dressing spray seeding process, a better effect is achieved at the low construction cost, and the method is suitable for large-scale application and popularization.

Description

Technical Field

[0001] This invention relates to the field of hydroseeding technology, specifically to a hydroseeding ecological restoration method for rock slopes affected by weathering and alkali formation of silicate minerals. Background Technology

[0002] Hydroseeding, as a highly efficient method for slope ecological restoration, is widely used for vegetation restoration in exposed rock areas such as abandoned mine sites and highway / railway slopes. This technology artificially constructs a growth substrate to provide plants with an initial growth environment, thereby quickly achieving green coverage of exposed surfaces. However, in practical applications, especially in areas with alkaline bedrock, the success rate of vegetation restoration is often unsatisfactory. The core reason is that the acidity or alkalinity of the bedrock continuously affects the chemical environment of the hydroseeding soil through weathering and leaching. Plants are highly sensitive to pH levels during germination and early growth stages; excessively acidic or alkaline environments severely affect their physiological metabolic processes, leading to seed failure, seedling death, and other phenomena, rendering the initial restoration efforts futile.

[0003] In the process of ecological restoration through hydroseeding in alkaline bedrock areas, traditional hydroseeding techniques primarily focus on the nutrient composition and physical structure of the topsoil itself, but generally neglect the geochemical characteristics of the bedrock in the restoration area, especially the impact of the bedrock's pH environment on the early growth of restored vegetation. When the bedrock is alkaline (such as limestone, pH > 8.5), the alkaline components released by the bedrock will raise the pH value of the topsoil, making it highly alkaline. A highly alkaline environment will reduce the availability of some important nutrients in the soil (such as trace elements like iron, manganese, and zinc), which will also lead to low seed germination rates, hindered seedling growth, and ultimately poor vegetation restoration results, or even failure. Summary of the Invention

[0004] In view of this, the present invention provides an ecological restoration method for rock slopes affected by the weathering and alkali formation of silicate minerals through hydroseeding. This method addresses the problems of existing hydroseeding methods for alkaline bedrock, which do not fully consider the geochemical characteristics of the bedrock, especially the continuous impact of pH environment on the hydroseeding soil. These methods only focus on the initial pH adjustment of the hydroseeding soil and lack a long-term stabilization mechanism, resulting in a series of problems such as high cost, poor stability, and inability to actively adjust pH value.

[0005] To achieve the above objectives, this invention provides a method for ecological restoration of rock slopes affected by silicate mineral weathering and alkali formation through hydroseeding, comprising the following steps:

[0006] S1. Clean and level the bedrock slope containing silicate minerals with a pH > 8.5;

[0007] S2. An inorganic mineral film formed by uniformly spraying a 15-25 wt% phosphoric acid (H3PO4) solution onto the surface of the bedrock slope serves as a neutralizing layer.

[0008] S3. Spray a mixture of 5-10 wt% sulfur powder and 90-95 wt% leaf mold onto the surface of the neutralization layer to form a slow-release layer.

[0009] S4. Spray topsoil on the surface of the slow-release layer. The topsoil contains herbaceous plant seeds.

[0010] As a further preferred technical solution of the present invention, when cleaning and leveling the bedrock slope, the surface cracks and pits of the bedrock slope are filled with the slow-release layer mixture prepared in step S3.

[0011] As a further preferred technical solution of the present invention, a phosphoric acid (H3PO4) solution is sprayed onto the surface of the bedrock slope using a drone or manual labor.

[0012] As a further preferred embodiment of the present invention, the particle size of the sulfur powder is 0.05-0.5 mm.

[0013] As a further preferred embodiment of the present invention, the mass percentage concentration of the phosphoric acid (H3PO4) solution is 20%.

[0014] As a further preferred technical solution of the present invention, the leaf mold is soil made from the decomposed leaves of broad-leaved trees, and even more preferably soil made from the decomposed leaves of at least one of maple, sycamore, paulownia, and oak trees.

[0015] As a further preferred embodiment of the present invention, the thickness of the sustained-release layer is 3-6 cm.

[0016] As a further preferred technical solution of the present invention, after spraying the mixture of sulfur powder and leaf mold, compaction treatment is carried out.

[0017] Mechanism of action of this invention: The alkalinity of bedrock slopes is caused by silicate minerals. To address this, a neutralization layer is first installed on the bedrock slope using a 20wt% phosphoric acid (H3PO4) solution. This solution is mildly acidic and can form insoluble salts with metal ions. The resulting calcium / magnesium phosphate precipitates accumulate on the slope surface, forming a dense inorganic mineral film. This film is structurally stable, resistant to water erosion, and effectively blocks water from interacting with the internal calcium carbonate deposits. 2+ OH - The contact layer prevents alkaline substances from dissolving further; a slow-release layer is then set on the neutralization layer, in which sulfur powder can slowly release acidic substances under the action of microorganisms, reducing the alkalinity of the environment; the leaf mold is soil made from the decomposed leaves of broad-leaved trees, which is rich in organic acids and humus, which can not only further help regulate the pH value, but also provide certain nutrients for plant growth, while its loose structure is conducive to air permeability and water retention.

[0018] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0019] 1) This invention uses a "phosphoric acid solution" as a neutralizing layer material and "sulfur powder + leaf mold" as a slow-release layer material. When ecologically restoring alkaline slopes, the synergistic effect of the neutralizing layer and the slow-release layer can quickly improve the alkaline environment of the slope and maintain the stability of the slope's acid-base environment for more than a year.

[0020] 2) Before traditional topsoil spraying, the present invention applies a neutralization layer and a slow-release layer as an isolation layer between the slope environment and the topsoil environment. This can effectively isolate and neutralize the alkaline substances released by the bedrock of the slope, and provide a suitable acid-base environment for the germination and growth of plants in the topsoil. One application can provide a stable acid-base environment for the topsoil for more than one year.

[0021] 3) The materials selected in this invention are readily available and inexpensive, and the construction process is basically similar to the traditional topsoil spraying process. It achieves better results at a lower construction cost and is suitable for large-scale promotion and application.

[0022] 4) The ecological restoration method of this invention, through long-term monitoring of the topsoil and restoration plants after hydroseeding, found that the pH value of the topsoil remained stable between 6.5 and 7.2. The germination rate of the plants reached over 82% after half a month of growth, and the plant coverage index was over 0.85 after three months. Even one year after hydroseeding (December), the pH value of the topsoil remained between 6.3 and 7.2, and the root system of the plants extended into the buffer layer and into the cracks of the bedrock layer of the slope. Detailed Implementation

[0023] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0024] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this invention pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0025] All the following examples and comparative examples were carried out simultaneously, with bedrock (such as limestone) slopes containing silicate minerals (pH=8.8, ±0.2) as the vegetation restoration targets, and the mixed materials (plant seeds, growth substrate, fertilizer, water-retaining agent, etc.) and processes for topsoil spraying were the same.

[0026] Comparative Example 1

[0027] Vegetation restoration was carried out using conventional hydroseeding techniques, as detailed below:

[0028] S1, Regarding the area The bedrock slope containing silicate minerals was cleaned and leveled.

[0029] S2. Apply the following topsoil spraying materials:

[0030] Mix 40wt% planting soil, 25wt% peat moss, 15wt% sheep manure, 13wt% straw powder, 2wt% water-retaining agent (polyacrylamide), and 5wt% binder (xanthan gum) evenly. Add plant seeds (alfalfa: tall ewe: ryegrass = 3:2:2) to prepare a topsoil spraying material with a moisture content of 15wt%. Finally, spray the topsoil onto the slope to form a topsoil spraying layer with a thickness of 8cm-10cm.

[0031] Example 1

[0032] This embodiment provides an ecological restoration method for alkaline bedrock slopes based on hydroseeding technology, which includes a pre-set neutralization buffer layer (neutralization layer + slow-release layer). The details are as follows:

[0033] S1, Regarding the area The bedrock slope containing silicate minerals was cleaned and leveled.

[0034] S2. A 20wt% phosphoric acid (H3PO4) aqueous solution is uniformly sprayed onto the surface of the bedrock slope using a drone. The inorganic mineral film formed by the reaction of phosphate and metal ions in silicate minerals serves as a neutralization layer.

[0035] S3. Mix 5% sulfur powder and 95% leaf mold evenly by weight percentage, then spray it on the surface of the neutralization layer and compact it to obtain a slow-release layer with a thickness of 5cm. The leaf mold is soil made from the decomposed leaves of broad-leaved trees (maple trees) for 6 months.

[0036] S4. Spray topsoil onto the surface of the slow-release layer, following the same procedure as step S2 in Comparative Example 1.

[0037] Comparative Example 2

[0038] As a control experiment for Example 1, the only difference is that step S3 is omitted, i.e., only a neutralization layer is sprayed with a 20wt% phosphoric acid (H3PO4) aqueous solution before the topsoil is sprayed. The rest of the process is the same as in Example 1.

[0039] Comparative Example 3

[0040] As a control experiment for Example 1, the only difference was that the sulfur powder in step S3 was omitted, and a 5cm slow-release layer was formed by spraying with 100wt% leaf mold. The rest of the process remained the same as in Example 1.

[0041] Example 2

[0042] The only difference from Example 1 is that the spraying mixture in step S3 is adjusted to contain 10 wt% sulfur powder and 90 wt% leaf mold. All other processes are the same as in Example 1.

[0043] Example 3

[0044] The only difference from Example 1 is that the spraying mixture in step S3 is adjusted to contain 15 wt% sulfur powder and 85 wt% leaf mold. All other processes are the same as in Example 1.

[0045] Comparative Example 4

[0046] The only difference from Example 1 is that the spraying mixture in step S3 is adjusted to contain 20 wt% sulfur powder and 80 wt% leaf mold. All other processes are the same as in Example 1.

[0047] Comparative Example 5

[0048] As a control experiment for Example 1, the only difference is that step S2 is omitted, i.e., only a slow-release layer with a thickness of 5 cm (5 wt% sulfur powder + 95 wt% leaf mold) is set before topsoil spraying. All other processes are consistent with Example 1.

[0049] Comparative Example 6

[0050] As a control experiment for Example 1, the only difference from Example 1 is that the concentration of the phosphoric acid aqueous solution in step S2 is adjusted to 5%. All other processes are the same as in Example 1.

[0051] Comparative Example 7

[0052] As a control experiment for Example 1, the only difference from Example 1 is that the concentration of the phosphoric acid aqueous solution in step S2 is adjusted to 10%. All other processes are the same as in Example 1.

[0053] Example 4

[0054] The only difference from Example 1 is that the concentration of phosphoric acid in step S2 is 15%. All other processes are the same as in Example 1.

[0055] Example 5

[0056] The only difference from Example 1 is that the concentration of phosphoric acid in step S2 is 25%. All other processes are the same as in Example 1.

[0057] Comparative Example 8

[0058] As a control experiment for Example 1, the only difference from Example 1 is that the concentration of phosphoric acid in step S2 is 30%. All other processes are the same as in Example 1.

[0059] Example 6

[0060] As a control experiment for Example 1, the only difference from Example 1 is that the leaf mold in step S3 is replaced with soil made from decomposed straw particles. All other processes are the same as in Example 1.

[0061] Tables 1 and 2 show the changes in soil pH and vegetation cover of Examples 1-6 and Comparative Examples 1-8 with different formulations of neutralized and slow-release layers, respectively. The starting date is the day after topsoil spraying. Soil pH data are recorded from day 7 to month 12, and vegetation cover index data are recorded from day 7 to month 3.

[0062] Table 1: Statistical table of pH values ​​at different times for the examples and comparative examples

[0063]

[0064] The vegetation index was calculated using a UAV multispectral lens by scanning the vertical projection area of ​​different blocks. The flight altitude was set to 60cm, the flight speed to 2m / s, and the overlap rate to be at least 80% front-to-back and 70% left-to-right. The vegetation cover was calculated using the Modified Soil Vegetation Index (MSAVI), with the following formula:

[0065]

[0066] NIR represents the near-infrared band, RED represents the red band, and L is the soil regulating factor.

[0067] Changes in vegetation cover over different time periods reflect, to some extent, the germination of plant seeds and the growth of vegetation. This demonstrates the impact of different formulations and comparative proportions on plant growth.

[0068] Table 2: Statistical table of vegetation index (MSAVI) at different times for the examples and comparative examples

[0069]

[0070] Based on the experimental data in Tables 1 and 2, and comparing Examples 1, 2, and 3 with Comparative Examples 3 and 4, it can be seen that the slow-release layer can maintain the stability of the pH value of the imported soil for a long time, and the sulfur powder in the slow-release layer plays a major role, with the optimal range of sulfur powder being 5%-15%. Comparing Examples 1, 4, and 5 with Comparative Examples 5, 6, 7, and 8, it can be found that phosphoric acid plays an important role in rapidly restoring the acid-base environment. The concentration of phosphoric acid solution is a crucial factor affecting the imported soil environment. Without phosphoric acid solution or with a low concentration, the acid-base environment cannot be quickly improved, affecting plant germination and thus the vegetation cover index. Applying excessively high phosphate concentrations leads to an acidic environment in the imported soil, which also affects plant growth. Therefore, through experimental comparison, the phosphoric acid concentration was determined to be 15%-25%, with 20% being optimal. Example 6, using soil derived from decomposed straw particles, showed inferior pH regulation and plant growth compared to Example 1. This is because soil derived from decomposed broadleaf tree leaves is rich in organic acids and humus, resulting in a significantly better pH regulation effect than materials like straw, thus promoting plant growth. In summary, the method of this invention can rapidly neutralize the alkalinity of the slope in the early stages of plant germination, providing a stable acid-base environment for germination and maintaining this stable environment throughout the entire plant growth process.

[0071] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and various changes or modifications can be made to these embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is defined only by the appended claims.

Claims

1. A method for ecological restoration of rock slopes affected by silicate mineral weathering and alkali formation through hydroseeding, characterized in that, Includes the following steps: S1. Clean and level the bedrock slope containing silicate minerals with a pH > 8.5; S2. An inorganic mineral film formed by uniformly spraying a 15-25 wt% phosphoric acid solution onto the surface of the bedrock slope serves as a neutralizing layer. S3. Spray a mixture of 5-10 wt% sulfur powder and 90-95 wt% leaf mold onto the surface of the neutralization layer to form a slow-release layer. S4. Spray topsoil on the surface of the slow-release layer. The topsoil contains herbaceous plant seeds.

2. The method for ecological restoration of rock slopes affected by silicate mineral weathering and alkali formation through spraying according to claim 1, characterized in that, When cleaning and leveling the bedrock slope, the surface cracks and pits of the bedrock slope are filled with the slow-release mixture prepared in step S3.

3. The method for ecological restoration of rock slopes affected by silicate mineral weathering and alkali formation through spraying according to claim 1, characterized in that, Phosphoric acid solution is sprayed onto the surface of bedrock slopes using drones or manual labor.

4. The method for ecological restoration of rock slopes affected by silicate mineral weathering and alkali formation through spraying according to claim 1, characterized in that, The particle size of sulfur powder is 0.05-0.5 mm.

5. The method for ecological restoration of rock slopes affected by silicate mineral weathering and alkali formation through spraying according to claim 1, characterized in that, The phosphoric acid solution has a mass percentage concentration of 20%.

6. The method for ecological restoration of rock slopes affected by silicate mineral weathering and alkali formation through spraying according to claim 1, characterized in that, The leaf mold is soil made from the decomposed leaves of broad-leaved trees.

7. The method for ecological restoration of rock slopes affected by silicate mineral weathering and alkali formation through spraying according to claim 1, characterized in that, The leaf mold is soil made from the decomposed leaves of at least one of the following trees: maple, sycamore, paulownia, and oak.

8. The method for ecological restoration of rock slopes affected by silicate mineral weathering and alkali formation through spraying according to claim 1, characterized in that, The thickness of the sustained-release layer is 3-6 cm.

9. The method for ecological restoration of rock slopes affected by silicate mineral weathering and alkali formation through hydroseeding according to any one of claims 1-8, characterized in that, After spraying the mixture of sulfur powder and leaf mold, compact it.

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