Spray-seeding ecological restoration method for sulfide oxidation acidification rock slope

Abstract

The invention relates to the technical field of spray-seeding, and discloses a sulfide oxidation acidification rock slope spray-seeding ecological restoration method which comprises the following steps: cleaning and leveling an acidic bedrock area; the method comprises the following steps: firstly, spraying a microbial inhibitor on the surface of a bedrock slope, and then spray-seeding a mixture of phosphate powder and calcium carbonate powder or spray-seeding the mixture of the microbial inhibitor phosphate powder and calcium carbonate powder to form a neutralization layer; limestone powder and straw particles are mixed and then sprayed and sown on the surface of the neutralization layer to serve as 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. The composite structure of the neutralization layer and the slow-release layer is adopted as the buffer layer, acid-base substances released by bed rock can be effectively blocked and neutralized, a stable pH environment is provided for soil dressing, the effective buffer effect can be maintained for more than one year through one-time laying, and the key period of plant rooting is covered. And low-cost materials and a small amount of microorganisms are selected for inhibition, so that the engineering cost is reduced, and the method is suitable for large-scale popularization and application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of spray seeding, in particular to a sulfide oxidation acidification rock slope spray seeding ecological restoration method. BACKGROUND

[0002] Rock layers rich in pyrite (FeS2) and other reducing sulfides are widely distributed in China. Rock layers rich in sulfides exposed to the atmosphere due to tectonic movement or human engineering activities are prone to generate acidic water and some swelling sulfates under the action of water chemistry with dissolved oxygen. The rapid change of rock layer composition, structure and structure caused by acidic water not only occurs on the rock layer itself, causing rock damage, surrounding soil acidification, but also can promote the corrosion of related building materials in its adjacent rock layers and engineering buildings in contact with them, and the resulting ecological environment and slope protection failure problems are very prominent. Exposed rock slope is generally divided into three weathering types: unweathered, semi-weathered and fully weathered. Generally, the strength of soil acidity in rock slope is mainly related to the content of sulfide minerals, mainly pyrite, which is dispersedly distributed in the internal semi-weathered or unweathered black shale. Atmospheric precipitation or surface water containing dissolved oxygen enters the internal slope along the geological gap and generates acidic water, which is prone to dissolve other constituent minerals or cements in the internal slope, thereby causing rock mass structure damage and deterioration of the overall slope mechanical strength. Therefore, ecological restoration of acidic bedrock slope is the focus of attention at present.

[0003] As a high-efficiency ecological restoration method for rock slope, the guest soil spray seeding technology is widely used in vegetation restoration of mine wasteland, highway and railway slope and other rock exposed areas. The technology artificially constructs a growth substrate to provide an initial growth environment for plants, thereby quickly realizing greening coverage of exposed surfaces. However, in actual application, especially in areas where acidic bedrock is distributed, the success rate of vegetation restoration is often not ideal. The core reason is that the acidity and alkalinity of the bedrock will continuously affect the chemical environment of the guest soil through weathering, leaching and other actions. Plants are very sensitive to pH value during germination and early growth stage, and an excessively acidic environment will seriously affect their physiological metabolism process, leading to seed non-germination, seedling death and other phenomena, making the early restoration investment go to waste.

[0004] At present, the industry lacks understanding of the influence of bedrock acidity on guest soil spray seeding, and lacks targeted technical measures. In some restoration projects, acid-base regulators may be directly added to the guest soil, but this method has obvious defects: first, the adjustment effect is short-term and difficult to resist the continuous release of acidity from the bedrock; second, the adjustment agent is not evenly mixed with the guest soil, which easily causes excessive local pH value fluctuation; third, for large-scale restoration projects, the cost is high and the economy is poor. Therefore, there is an urgent need for a technical solution that can long-term and stably adjust the pH value of the guest soil and has an appropriate cost to cope with the adverse effects of acidic bedrock on guest soil spray seeding vegetation restoration. SUMMARY

[0005] In view of this, the present application provides a sulfide oxidation acidification rock slope spray seeding ecological restoration technology to solve the problem that the existing acid base rock guest soil spray seeding does not fully consider the geochemical characteristics of the base rock, especially the continuous influence of the pH environment on the guest soil, only focuses on the adjustment of the initial pH of the guest soil, lacks a long-acting stable mechanism, and results in a series of problems such as high cost, poor stability, and inability to actively adjust the pH value.

[0006] To achieve the above-mentioned purpose, the present application provides a sulfide oxidation acidification rock slope spray seeding ecological restoration method, which comprises the following steps:

[0007] S1, cleaning and leveling the base rock (such as quartzite) slope with pH < 5.5 containing sulfide;

[0008] S2, first spraying a mixed solution of a microbial inhibitor and water on the surface of the base rock slope, and then spraying a mixture of 15-30wt% phosphate powder and 70-85wt% calcium carbonate powder on the surface of the base rock slope to form a neutralization layer;

[0009] Alternatively, a mixture of 3-5wt% microbial inhibitor, 15-30wt% phosphate powder and 70-85wt% calcium carbonate powder is sprayed on the surface of the base rock slope to form a neutralization layer;

[0010] S3, spraying a mixture of 25-35wt% limestone powder and 65-75wt% straw particles on the surface of the neutralization layer to form a slow-release layer;

[0011] S4, spraying guest soil on the surface of the slow-release layer, and the guest soil is mixed with local adapted herbaceous plant seeds.

[0012] As a further preferred technical solution of the present application, when the base rock slope is cleaned and leveled, the surface cracks and pits of the base rock slope are filled and leveled by the slow-release layer mixture prepared in step S3.

[0013] As a further preferred technical solution of the present application, the microbial inhibitor solution is sprayed on the surface of the base rock slope by an unmanned aerial vehicle or manually in step S2.

[0014] As a further preferred technical solution of the present application, the microbial inhibitor and water are prepared into a solution with a concentration of 6-8mg / L in step S2.

[0015] As a further preferred technical solution of the present application, when the microbial inhibitor is in the form of spraying, a mixture is formed by 25wt% of phosphate powder and 75wt% of calcium carbonate powder; when the microbial inhibitor is in the form of mixed spraying and seeding, a mixture is formed by 5wt% of microbial inhibitor, 20wt% of phosphate powder and 75wt% of calcium carbonate powder.

[0016] As a further preferred technical solution of the present application, the mixture in step S3 is composed of 30wt% of medium limestone powder and 70wt% of straw particles.

[0017] As a further preferred technical solution of the present application, the thickness of the neutralization layer is 1-3 cm, and the thickness of the slow-release layer is 3-5 cm.

[0018] As a further preferred technical solution of the present application, the length of the straw particles is 1-3 cm, and the straw is crop wheat straw, corn straw, etc.

[0019] As a further preferred technical solution of the present application, the phosphate powder is selected from calcium phosphate commonly used in agricultural fertilizers; and the microbial inhibitor is selected from sodium dodecyl sulfate (SDS) or sodium benzoate.

[0020] As a further preferred technical solution of the present application, after the neutralization layer and the slow-release layer are sprayed and seeded, compaction treatment is performed.

[0021] The mechanism of action of the present application is as follows: sulfides (such as pyrite FeS2) contained in the acidic bedrock undergo oxidation reaction in the presence of water and oxygen to generate acidic substances such as sulfuric acid. The neutralization layer and the surface of the acidic bedrock slope, in which the calcium carbonate powder acts as a rapid acid neutralizer, can rapidly neutralize the acid generated by oxidation, and the calcium sulfate formed by the reaction of calcium carbonate and sulfuric acid (CaCO3+ H2SO4= CaSO4+ CO2↑ + H2O) is difficult to dissolve in water. Calcium sulfate will gradually precipitate on the surface of the rock or in the pores, forming a dense calcium sulfate crystal film that prevents sulfides from contacting oxygen and water, thereby controlling the generation of acidity; the biological oxidation process of sulfides is inhibited by pre-spraying a microbial inhibitor solution using a microbial inactivator; the addition of phosphate and iron ions forms insoluble phosphate minerals, thereby reducing the oxidation of pyrite by iron ions and forming a film on the surface of pyrite to further inhibit the oxidation of pyrite. The straw fiber structure in the slow-release layer can provide support to prevent the limestone powder from concentrating and settling during the laying and subsequent spraying process, ensuring the uniformity of the buffer layer (neutralization layer + slow-release layer). The slow-release layer also serves to isolate the neutralization layer and the guest soil layer, so that the added microbial inhibitor does not affect the microorganisms in the guest soil layer, thereby maximizing the effect of the microbial inhibitor.

[0022] Compared with the prior art, the present application can achieve the following beneficial effects:

[0023] 1) The present application uses "microbial inhibition + phosphate + limestone powder" as the neutralization layer material, and "limestone powder + straw" as the slow-release layer material. In the repair of acid bedrock side slopes, through the synergistic mechanism of each component, the stability and durability of pH adjustment effect are ensured, and the pH value of the guest soil is maintained in the range suitable for the early growth of plants.

[0024] 2) The present application uses a neutralization layer + slow-release layer composite structure at the bottom of the guest soil layer as a buffer layer, which can effectively block and neutralize the acid and alkaline substances released by the bedrock, providing a stable pH environment for the guest soil. Once laid, it can maintain effective buffering effect for more than 1 year, covering the key period of plant root penetration.

[0025] 3) The present application selects low-cost materials (limestone powder, straw, phosphate) and a small amount of microbial inhibition, which reduces the engineering cost and is suitable for large-scale popularization and application.

[0026] 4) The ecological restoration method of the present application can maintain the pH value of the guest soil between 6.2 and 6.8 through regular monitoring after spraying and seeding. After 3 months, the seed germination rate can reach more than 85%, the seedlings grow healthily, the vegetation coverage is significantly improved compared with traditional guest soil spraying and seeding, and after 1 year (12 months), the pH value of the guest soil still maintains above 6.0, the plant roots have penetrated into the buffer layer and begun to extend to the bedrock fissures, and the vegetation community tends to be stable. DETAILED DESCRIPTION

[0027] The specific embodiments of the present application will be described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0028] Unless defined, the technical terms used in the following examples have the same meaning as generally understood by those skilled in the art to which the present application belongs. The test reagents used in the following examples, unless otherwise specified, are conventional biochemical reagents; the experimental methods, unless otherwise specified, are conventional methods.

[0029] All the following examples and comparative examples use bedrock slopes containing sulfides (pH = 3.2, positive and negative not more than 0.2) as the object of vegetation restoration, and the mixed materials (plant seeds, growth substrate, fertilizer, water retaining agent, etc.) and process of guest soil spraying and seeding are the same.

[0030] Comparative Example 1

[0031] Vegetation restoration is carried out by using conventional guest soil spraying and seeding technology, as follows:

[0032] S1, clean and level the bedrock slope containing sulfides;

[0033] S2, the following guest soil spray seeding material is sprayed:

[0034] Planting soil 40wt%, grass charcoal soil 25wt%, sheep manure 15wt%, straw powder 13wt%, water retaining agent (polyacrylamide) 2wt%, adhesive (xanthan gum) 5wt% are mixed uniformly, plant seeds (alfalfa: esparto grass: rye grass = 3:2:2) are added, a guest soil spray seeding material with a water content of 15wt% is prepared, and finally sprayed on the slope to form a guest soil spray seeding layer with a thickness of 8cm-10cm.

[0035] Example 1

[0036] The ecological restoration method for the acid bedrock slope provided by the embodiment is specific as follows:

[0037] S1, the bedrock slope containing sulfide is cleaned and leveled;

[0038] S2, first, a water solution of 7.5mg / L of the microbial inhibitor sodium dodecyl sulfate (SDS) is sprayed on the bedrock slope; then, calcium phosphate powder 20% and calcium carbonate powder 80% are mixed uniformly according to the mass percentage, and then sprayed, compacted, to obtain a neutralizing layer with a thickness of 3cm;

[0039] S3, limestone powder 30% and wheat straw particles (length 1-3cm) 70% are mixed uniformly according to the mass percentage, and then sprayed on the surface of the neutralizing layer, compacted, to obtain a slow-release layer with a thickness of 5cm;

[0040] S4, the guest soil spray seeding is performed on the surface of the slow-release layer, and the specific operation is the same as that in step S2 in Comparative Example 1.

[0041] Example 2

[0042] The embodiment and Example 1 are the same in process steps, and the only difference is that the microbial inhibitor used is sodium benzoate, and the solution concentration is 10.0mg / L.

[0043] Example 3

[0044] The embodiment and Example 1 are the same in process steps, and the only difference is that the microbial inhibitor sodium dodecyl sulfate (SDS) used is a solid powder, and calcium phosphate powder 20%, microbial inhibitor 5% and calcium carbonate powder 75% are mixed uniformly according to the mass percentage as the neutralizing layer.

[0045] Comparative Example 2

[0046] As a control experiment of Example 1, the only difference from Example 1 is that step S2 is omitted, i.e. only a 5cm slow-release layer is provided before the guest soil is sprayed.

[0047] Comparative Example 3

[0048] As a control experiment of Example 1, the only difference from Example 1 is that the ratio in the neutralization layer is adjusted, i.e. the calcium phosphate powder 5wt% is mixed with the calcium carbonate powder 95wt% uniformly before spraying.

[0049] Comparative Example 4

[0050] As a control experiment of Example 1, the only difference from Example 1 is that the phosphate is omitted in the neutralization layer, i.e. spraying with 100wt% calcium carbonate powder to form the neutralization layer.

[0051] Comparative Example 5

[0052] As a control experiment of Example 1, the only difference from Example 1 is that the aqueous solution of the microbial inhibitor (SDS) is omitted in the neutralization layer, i.e. spraying with only the mixture of 20wt% phosphate powder + 80wt% calcium carbonate powder to form the neutralization layer.

[0053] Table 1 and Table 2 are the pH values and vegetation coverage changes of the guest soil of the neutralization layer and the slow-release layer of Examples 1-3 and Comparative Examples 1-5 of different formulations, respectively, wherein the day after the guest soil is sprayed is taken as the starting date, and the data from the 7th day to 12 months are recorded.

[0054] Table 1: pH value statistical table of different months of examples and comparative examples

[0055]

[0056] The vertical projection area scanning is performed on different blocks by using the unmanned aerial vehicle multi-spectral lens to calculate the vegetation index, the flight height is set to 60cm, the flight speed, the overlap rate (80% front and back, more than 70% left and right). The modified soil vegetation index (MSAVI) is used to calculate the coverage of vegetation, and the calculation formula is as follows:

[0057]

[0058] Wherein NIR represents the near-infrared band, RED represents the red light band, and L is the soil adjustment factor.

[0059] The change of vegetation coverage at different times reflects the germination of plant seeds and the growth of vegetation to some extent. It shows the influence of the ratio of different examples and comparative examples on plant growth.

[0060] Table 2: Vegetation index (MSAVI) statistical table of different times of examples and comparative examples

[0061]

[0062] In combination with the experimental data in Tables 1 and 2, it is found through comparative analysis of Examples 1, 2, 3 and Comparative Examples 1 to 5 that the method proposed in the present application plays an important role in maintaining the stability of the pH value of the guest soil and promoting plant growth; compared with Example 1, Example 2 changes the inhibitor, and the inhibitor of Example 3 is mixed with other neutralizing materials for spraying and seeding, and the effects of both are slightly worse than that of Example 1. Compared with Example 1, the plants in each comparative example show a significant decrease in growth index after about 7 days, and the pH value is significantly lower than that of Example 1, indicating that the neutralizing layer can ensure the stability and durability of the pH adjustment effect through the synergistic mechanism of each component in the repair of the acid bedrock slope. Moreover, the data show that the method of the present application can quickly adjust the pH value of the acid bedrock slope in a short period of time to create a stable environment for plant germination; in the subsequent monitoring process, it can be seen that the pH value of Example 1 is always stable above 6.0, while the pH value of the comparative examples cannot quickly rise above 6.0 or appears a significant acid return phenomenon in the later period. In summary, the method of the present application can provide a stable acid-base environment throughout the plant growth process.

[0063] Although the specific embodiments of the present application are described above, those skilled in the art should understand that these are only illustrative, and various changes or modifications can be made to the present embodiments without departing from the principles and essence of the present application, and the protection scope of the present application is only limited by the appended claims.

Claims

1. A sulfide-oxidizing acidogenic rock slope spray-seeding ecological restoration method, characterized in that, The method comprises the following steps: S1, cleaning and leveling the bedrock slope with pH < 5.5 containing sulfide; S2, spraying a mixed solution of microbial inhibitor and water on the surface of the bedrock slope, and then spraying a mixture of 15-30wt% phosphate powder and 70-85wt% calcium carbonate powder on the surface of the bedrock slope to form a neutralization layer; Or, spraying a mixture of 3-5wt% microbial inhibitor, 15-30wt% phosphate powder and 70-85wt% calcium carbonate powder on the surface of the bedrock slope to form a neutralization layer; S3, spraying a mixture of 25-35wt% limestone powder and 65-75wt% straw particles on the surface of the neutralization layer to form a slow-release layer; S4, spraying a guest soil on the surface of the slow-release layer, and mixing herbaceous plant seeds in the guest soil.

2. The sulfide-oxidizing-acidogenic rock slope spspray-and-broadcast ecological restoration method according to claim 1, characterized in that, When the bedrock slope is cleaned and leveled, the surface cracks and pits of the bedrock slope are filled and leveled by the slow-release layer mixture prepared in step S3.

3. The sulfide-oxidizing-acidogenic rock slope spspray-and-broadcast ecological restoration method of claim 1, wherein, The microbial inhibitor solution is sprayed on the surface of the bedrock slope by using a drone or manually.

4. The sulfide-oxidizing-acidogenic rock slope spspray-and-blanket ecological restoration method of claim 1, wherein, The microbial inhibitor is mixed with water at a concentration of 6-8mg / L to prepare a solution.

5. The sulfide-oxidizing-acidogenic rock slope spspray-and-blanket ecological restoration method of claim 1, wherein, When the microbial inhibitor is sprayed, a mixture of 25wt% phosphate powder and 75wt% calcium carbonate powder is formed; when the microbial inhibitor is mixed and sprayed, a mixture of 5wt% microbial inhibitor, 20wt% phosphate powder and 75wt% calcium carbonate powder is formed.

6. The sulfide-oxidizing-acidogenic rock slope spspray-and-blanket ecological restoration method of claim 1, wherein, The slow-release layer mixture is composed of 30wt% medium limestone powder and 70wt% straw particles.

7. The sulfide-oxidizing, acid-generating rock slope spspray-and-blanket ecological restoration method of claim 1, wherein, The thickness of the neutralization layer is 1-3cm, and the thickness of the slow-release layer is 3-5cm.

8. The sulfide-oxidizing, acid-generating rock slope spspray-and-blanket ecological restoration method of claim 1, wherein, The length of the straw particles is 1-3cm.

9. The sulfide-oxidizing, acid-generating rock slope spspray-and-blanket ecological restoration method of claim 1, wherein, The phosphate powder is selected from calcium phosphate; the microbial inhibitor is selected from sodium dodecyl sulfate (SDS) or sodium benzoate.

10. The sulfide oxidation-induced acid rock slope spray-seeding ecological restoration method according to any one of claims 1-9, characterized in that, After spraying the neutralization layer and the slow-release layer, both are subjected to compaction treatment.

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