Ecological restoration method for high and cold mining wasteland

Abstract

The invention discloses an ecological restoration method for high and cold mining wasteland, and belongs to the technical field of ecological restoration of mining areas. The ecological restoration method for the high and cold mining wasteland comprises the following steps: (1) surveying and quantifying the field; (2) landform improvement and soil pretreatment; (3) soil improvement; (4) inoculating functional microorganisms; (5) coldproof plant configuration and habitat maintenance. The invention provides a comprehensive remediation method integrating cold-resistant plant screening, soil matrix targeted improvement, functional microorganism and plant coupling remediation and auxiliary engineering measures, and aims to effectively solve the key problems of low vegetation survival rate, soil depletion, poor matrix stability, limited microbial activity and the like in ecological remediation of high and cold mining areas. And rapid, stable and sustainable ecological restoration of waste land is realized.

Description

Technical Field

[0001] This invention relates to the field of ecological restoration technology for mining areas, specifically to an ecological restoration method for abandoned mining sites in high-altitude and cold regions. Background Technology

[0002] Mineral resource extraction activities inevitably generate a large number of abandoned sites (dumping grounds, tailings ponds, waste rock piles, open-pit mines, subsidence areas, etc.). These areas generally present extremely poor site conditions, constituting a fundamental obstacle to ecological restoration. The soil is not only extremely nutrient-poor, severely lacking in nitrogen, phosphorus and organic matter, but also has an extremely unstable physical structure, making it prone to erosion and landslides. More seriously, the soil is often highly acidic and has a huge potential for continuous acidification, while the content of heavy metals is seriously excessive and has strong biological toxicity.

[0003] The harsh climate conditions unique to high-altitude, cold mining areas amplify the aforementioned inherently adverse site conditions, significantly hindering the ecological restoration process. Extreme low temperatures and a very short effective growing season result in severely insufficient plant growth time, and a lack of effective accumulated temperature limits their growth rate; intense seasonal freeze-thaw cycles repeatedly damage soil structure, exacerbate nutrient leaching, damage plant roots, and significantly increase the risk of slope instability; strong solar radiation (especially ultraviolet radiation) and high evaporation rates from high altitudes easily trigger physiological drought in plants. Furthermore, the extremely limited window of opportunity for suitable construction and maintenance further increases the difficulty and cost of restoration.

[0004] Current ecological restoration technologies for such high-altitude, cold-weather mining wastelands have significant limitations: (1) Neglecting the role of plant communities in reducing acidic wastewater at the source: Current ecological restoration technologies overemphasize vegetation cover, seriously neglecting the potential core role of plant communities in reducing acidic mine drainage (AMD) at the source. Simply pursuing vegetation restoration without effectively inhibiting sulfide oxidation or neutralizing existing acidity through the synergistic effect of specific plants and their rhizosphere microorganisms results in short-lived "greening" effects and poor acid suppression, failing to fundamentally solve the core environmental problem of AMD pollution.

[0005] (2) Limitations and instability of functional microbial applications: Although the role of functional microorganisms such as sulfate-reducing bacteria (SRB) and urease-producing bacteria in the source control of AMD has received widespread attention, they generally have application bottlenecks (especially in high-altitude and cold environments). The activity of normal temperature strains is severely inhibited in extreme low temperature environments, making colonization difficult. Moreover, their efficacy is highly sensitive to drastic fluctuations in environmental conditions (such as pH, redox potential, nutrients, etc.), resulting in unstable and poor sustainability of acid suppression effects.

[0006] (3) Lack of effective synergy between microorganisms and plants: Existing technologies often separate microbial remediation from phytoremediation, failing to make full use of the favorable rhizosphere conditions created by plants (such as the anaerobic microenvironment formed by the root system of plants with well-developed roots to help SRB colonize better) to stabilize and enhance the activity and efficacy of functional microorganisms.

[0007] (4) Single measures are ineffective and lack systematicity: relying solely on fragmented and single technical measures such as covering with soil, sowing, applying general amendments or single microbial agents is difficult to achieve results in the complex and harsh environment of high-altitude mining areas, often leading to repeated failures in restoration, high costs, and extremely slow recovery of ecological functions.

[0008] Therefore, there is an urgent need for a comprehensive ecological restoration technology that can synergistically achieve the dual goals of vegetation restoration and reduction of acidic wastewater at the source, and effectively overcome multiple stresses from high altitude and cold. Its core lies in building a stable synergistic system between cold-resistant plants and specific functional microorganisms. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide an ecological restoration method for abandoned mining sites in high-altitude and cold regions.

[0010] To achieve the above objectives, the technical solution adopted by this invention is: an ecological restoration method for high-altitude mining wasteland, comprising the following steps: (1) Site survey and quantification: Determine the physical and chemical properties of the soil and calculate the dosage of amendment materials and microbial agents; (2) Terrain improvement and soil pretreatment: trimming slopes, backfilling water-collecting pits, covering gravel areas with soil, and tilling; (3) Soil improvement: Apply alkaline materials and organic composite matrix; (4) Inoculation with functional microorganisms: Inoculate with cold-resistant sulfate-reducing bacteria; (5) Cold-resistant plant configuration and habitat maintenance; planting a three-dimensional grass-shrub community and covering it with straw and mulch; The cold-resistant sulfate-reducing bacteria were enriched and domesticated from soil samples from the Jiama mining area in Tibet, China.

[0011] This invention provides a comprehensive restoration method that integrates cold-resistant plant screening, targeted soil matrix improvement, functional microorganism and plant coupling restoration, and auxiliary engineering measures. It aims to effectively solve key problems in the ecological restoration of high-altitude mining areas, such as low vegetation survival rate, infertile soil, poor matrix stability, and limited microbial activity, and achieve rapid, stable and sustainable ecological restoration of abandoned sites.

[0012] Preferably, step (1) involves conducting a baseline survey of the remediation area, measuring key physicochemical indicators of the soil, including soil acidification (pH value, net acid generation (NAG), net acid generation pH (NAG-pH)), heavy metal pollution in soil and surface water, and the content of nutrients such as carbon, nitrogen, and phosphorus. Based on the above data, the dosage of soil conditioner and microbial agent is accurately calculated to provide a basis for targeted remediation.

[0013] Preferably, the terrain improvement and soil pretreatment in step (2) include small-scale appropriate repair of the original slope and backfilling of waterlogged pits to facilitate subsequent ecological restoration operations. In areas with many rocks and severe soil deficiency, nearby soil is used for covering to create a continuous soil layer; the topsoil is tilled to a depth of 10-20 cm, and the walkways between the ridges naturally form strip-shaped ditches connected to the surrounding drainage ditches. Planting holes are arranged in a fish-scale pattern between the ditches. Toxic substances in the soil are leached by natural rainfall or artificial irrigation to initially dilute the acidity.

[0014] As a preferred embodiment of the ecological restoration method for high-altitude mining wastelands described in this invention, the cold-resistant sulfate-reducing bacterial community includes *Campylobacter*, *Campylobacter*, and *Clostridium*. As a preferred embodiment of the ecological restoration method for high-altitude mining wastelands described in this invention, the cold-resistant sulfate-reducing bacterial community includes *Campylobacter* spp. with an abundance percentage of 60-63%. Desulfosporosinus Clostridium species with an abundance percentage of 20-28% ( Clostridium_sensu_stricto _10) and Clostridium species with an abundance percentage of 10-15% ( Lachnoclostridium ).

[0015] As a preferred embodiment of the ecological restoration method for high-altitude mining wasteland described in this invention, the method for enriching and acclimatizing the cold-resistant sulfate-reducing bacteria includes the following steps: (1) Enrichment of cold-resistant sulfate-reducing bacteria: Soil samples were weighed and inoculated into modified Postgate liquid medium, and primary anaerobic enrichment was carried out under multiple gradient conditions. (2) Low-temperature acclimatization of cold-resistant sulfate-reducing bacteria: When the culture medium in step (1) changes from clear to dark black or black precipitate, the bacterial solution is transferred to a modified Postgate liquid medium at 15°C and pH unchanged for continued culture. The transfer is repeated 6-7 times. Each time the culture temperature is reduced by 1°C until the culture temperature is 10°C.

[0016] Preferably, the modified Postgate liquid culture medium comprises (NH4)2SO4 0.45 g / L, KCl 0.05 g / L, MgSO4·4H2O 0.5 g / L, KH2PO4 0.05 g / L, Ca(NO3)2·4H2O 0.014 g / L, yeast extract 0.2 g / L, glycerol 0.92 g / L, FeSO4·7H2O 0.5 g / L, ascorbic acid 0.02 g / L, and sodium thioacetate 0.1 g / L.

[0017] More preferably, the modified Postgate liquid culture medium is stripped with high-purity nitrogen for at least 20 minutes to remove dissolved oxygen.

[0018] In a preferred embodiment of the ecological restoration method for high-altitude mining wasteland described in this invention, the alkaline material in step (3) is slaked lime; the formula for calculating the amount of slaked lime used is: (a) The net acid production (NAG) per ton of acidic soil is calculated as follows: Where m is the volume of sodium hydroxide standard solution consumed in the determination of NAG; w is the mass of the soil sample weighed in the determination of NAG; (b) The amount of Ca(OH)2 required to neutralize one ton of acidic soil: (b) Estimate the total amount of Ca(OH)2 required for a remediation area of ​​area b and remediation depth a: Where b represents the area of ​​soil to be remediated; a represents the planned depth of soil improvement.

[0019] As a preferred embodiment of the ecological restoration method for high-altitude mining wasteland described in this invention, the organic composite matrix in step (3) includes yak dung and riverbed sediment; the mass ratio of yak dung to riverbed sediment in the organic composite matrix is ​​yak dung: riverbed sediment = 2:1.

[0020] Preferably, the organic composite matrix material is mainly composed of yak manure and supplemented with riverbed sediment. The yak manure and riverbed sediment are mixed at a ratio of 2:1, and the application rate is determined based on the soil's carbon, nitrogen, and phosphorus deficit. The amendment material is evenly spread in the trenches, lightly compacted, and backfilled, then allowed to equilibrate for 7 to 15 days to ensure full contact between the amendment material and the mine soil.

[0021] Preferably, the heavy metal content of the riverbed sediment meets the "GB15618–2018" standard for soil environmental quality and risk control of soil pollution in agricultural land.

[0022] As a preferred embodiment of the ecological restoration method for high-altitude mining wasteland described in this invention, the cold-resistant sulfate-reducing bacteria have a sulfate reduction rate of ≥70% at 10℃.

[0023] As a preferred embodiment of the ecological restoration method for high-altitude mining wasteland described in this invention, the calculation formula for the dosage of cold-resistant sulfate-reducing bacteria in step (4) is as follows: The target concentration is 1×10 8 - 1×10 10 CFU / kg, bacterial concentration 1×10 10 - 1×10 11 CFU / L, inoculation depth of 0.10 ~ 0.12 m.

[0024] As a preferred embodiment of the ecological restoration method for high-altitude mining wasteland described in this invention, the three-dimensional grass-shrub community in step (5) includes a herbaceous layer and a shrub layer; the plants in the herbaceous layer include *Leymus chinensis* (…). Elymus nodding Kentucky bluegrass ( ) Poa crymophila ), Purple fescue ( Red fescue ), ryegrass ( Lolium perpetual ), Alfalfa ( Medicago sativa ), Tibetan dandelion ( Tibetan dandelion Wolfsbane ( Stellera chamaejasme ), tall fescue ( Fescue elata ), alpine beans ( Himalayan Tibet ), Little Eyebrow Grass ( Lesser sphaerocephalon ), Sorrel ( Sorrel At least one of the following: the plants in the shrub layer include sea buckthorn (Hippophae rhamnoides). Sea buckthorn ), Golden Potentilla ( Dasiphora fruticosa Golden Flower Forearm ( Berber Wilson's ), alpine rhododendron ( Rhododendron lapponica ), multi-branched tamarisk ( Tamarix ramosissima At least one of the following.

[0025] Preferably, the three-dimensional grass-shrub community also includes the landscape plant Cosmos bipinnatus ( Cosmos bipinnatus ).

[0026] Based on field vegetation surveys and a comprehensive assessment of the heavy metal tolerance and seed availability of various vegetation types, the inventors of this application selected the aforementioned herbaceous and shrub plants to form a three-dimensional grass-shrub community for the remediation of high-altitude mining wastelands. The selected vegetation can grow in high-altitude mining wastelands and effectively reduce SO4 levels in the soil. 2- The content effectively curbs the generation of AMD from the source, achieving source control over AMD.

[0027] Preferably, the planting density of the herbaceous layer is 20 g / m². 2 The planting density of the shrub layer is 8 trees / m². 2 .

[0028] Preferably, in step (5), the covering straw and mulch film are specifically double-layered covering of barley straw and green mulch film; the mulch film is fixed with J-shaped steel anchors.

[0029] Preferably, the J-shaped steel anchors are spaced 0.5 m apart and penetrated ≥20 cm into the soil.

[0030] Preferably, the light transmittance of the mulch film is 40% to 60%.

[0031] Preferably, habitat maintenance in step (5) includes: watering thoroughly after planting to promote faster root growth and improve plant resistance; and covering with crop straw (3-5 cm thick) to prevent water evaporation and soil compaction caused by rainfall and irrigation.

[0032] The present invention also provides the application of the ecological restoration method for high-altitude mining wasteland in the restoration of high-altitude mining wasteland.

[0033] The beneficial effects of the present invention: The present invention provides an ecological restoration method for high-altitude mining wasteland. The present invention achieves the first deep synergy between functional microorganisms and cold-resistant plants in high-altitude mining areas and adopts double-layer covering to improve the stability of the microenvironment. It has the following advantages: (1) Source synergy to suppress acid and passivate heavy metals: Through the cold-resistant plant-functional microorganism synergy system, acidic substances can still be continuously neutralized in the environment of -5~10℃, and exchangeable heavy metals can be converted into residues at the same time, thus curbing the generation of AMD from the source and solving the pain point of "re-greening without suppressing acid" in the existing technology. (2) Realize the rapid ecological colonization of cold-resistant biological communities: The combination of grass and shrub such as Leymus chinensis and Hippophae rhamnoides is preferred and combined with low temperature (10℃) functional bacteria to improve the overwintering survival rate of plants. (3) Effective accumulated temperature and improved erosion resistance: The double protection mechanism formed by straw-mulch film double-layer covering effectively inhibits water evaporation and ground temperature fluctuation, significantly alleviates the damage of frost heave stress to soil structure, inhibits crack expansion and nutrient leaching caused by freeze-thaw cycle, and improves the erosion resistance of slope. Attached Figure Description

[0034] Figure 1 This is a genus-level composition diagram of the 16S rRNA gene sequencing results of the cold-resistant sulfate-reducing bacteria in Example 1.

[0035] Figure 2The changes in the pot experiment, total plant height, and soil sulfate content in Example 1 are shown. Different uppercase and lowercase letters indicate significant differences between treatments (Duncan test, P<0.05).

[0036] Figure 3 The image shows a comparison of the slope of the Jiama mining wasteland in Tibet before and after restoration, using the ecological restoration method of Example 1 for high-altitude mining wasteland. Detailed Implementation

[0037] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. In the following embodiments and comparative examples, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0038] The cold-resistant sulfate-reducing bacteria described in the following examples have a sulfate reduction rate of ≥70% at 10℃; the dosage of the cold-resistant sulfate-reducing bacteria is calculated using the following formula: The target concentration is 1×10 8 - 1×10 10 CFU / kg, bacterial concentration 1×10 10 - 1×10 11 CFU / L, inoculation depth of 0.10 ~ 0.12 m.

[0039] The organic composite substrate described in the following embodiments is yak manure and riverbed sediment; the mass ratio of yak manure to riverbed sediment is yak manure: riverbed sediment = 2:1, and the application rate is determined based on the carbon, nitrogen and phosphorus deficit in the soil; the heavy metal content of the riverbed sediment complies with GB15618–2018 "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard".

[0040] The culture medium used in the following examples: The modified Postgate liquid medium formulation is as follows: (NH4)2SO4 0.45 g / L, KCl 0.05 g / L, MgSO4·4H2O 0.5 g / L, KH2PO4 0.05 g / L, Ca(NO3)2·4H2O 0.014 g / L, yeast extract 0.2 g / L, glycerol 0.92 g / L, FeSO4·7H2O 0.5 g / L, ascorbic acid 0.02 g / L, sodium thioacetate 0.1 g / L.

[0041] Preparation of modified Postgate liquid medium: Prepare Postgate liquid medium according to the above formula, and strip it with high-purity nitrogen for at least 20 minutes to remove dissolved oxygen.

[0042] Example 1: Obtaining Cold-Resistant Sulfate-Reducing Bacteria This embodiment provides a method for enriching and acclimatizing cold-resistant sulfate-reducing bacteria. Ten tailings soil samples were collected from different areas (tailings and spoil heaps) and different seasons (summer and winter) in the Jiama mining area of ​​Tibet for enrichment and acclimatization. The specific steps include: (1) Enrichment of cold-resistant sulfate-reducing bacteria: 0.5 g of tailings soil sample collected from the Jiama mining area in Tibet was weighed and inoculated into 20 mL of modified Postgate liquid medium. Primary anaerobic enrichment was carried out under the conditions (pH 5.0, temperature 15℃). (2) Low-temperature acclimatization of cold-resistant sulfate-reducing bacteria: When the culture medium in step (1) changes from clear to dark black or has obvious black precipitate, take 5% (v / v) bacterial solution and transfer it to fresh modified Postgate liquid medium with constant temperature and pH for continued culture. Repeat the transfer 6–7 times. Each time, reduce the culture temperature by 1°C until the culture temperature is 10°C.

[0043] The community structure of sulfate-reducing bacteria enriched and trained in this embodiment was analyzed. One strain from 10 tailings soil samples was randomly selected and subjected to 16S rRNA gene sequencing analysis at the genus level. The genus-level classification is as follows: Figure 1 As shown. By Figure 1 It can be seen that the cold-resistant sulfate-reducing bacteria mainly belong to the genera *Campylobacter* (62%), *Clostridium* (25.2%), and *Clostridium* (11.9%).

[0044] The sulfate removal rate of the aforementioned cold-resistant sulfate-reducing bacteria was tested. The specific testing method was as follows: samples were taken during the lag phase and plateau phase after bacterial transfer. After filtering the bacterial solution through a 0.22 μm filter membrane, 2.5 mL was placed in a colorimetric tube, and distilled water was added to a final volume of 25 mL, followed by gentle shaking. The sulfate ion concentration in the bacterial solution was then calculated according to the "Determination of Sulfate in Water - Barium Chromate Spectrophotometric Method" (HJ 342-2021), and the sulfate removal rate was further obtained.

[0045] The test results are shown in Table 1. Under the low-temperature acidic conditions of 10±1℃ and pH 5.0, the above-mentioned cold-resistant sulfate-reducing bacteria still achieved a sulfate removal rate of 82.15%–93.98% (average 90%) in the simulated culture medium within 400 hours, which fully demonstrates that the bacteria have excellent and stable low-temperature sulfate reduction ability and reproducibility.

[0046] Table 1 Example 2 This embodiment simulates an ecological restoration method for spoil heaps in high-altitude mining areas of Tibet through a pot experiment in a greenhouse (10-15℃) at South China Normal University in Guangzhou. The specific steps include: (1) Site survey and quantification: The soil of the Niumatang spoil heap in Tibet was systematically sampled and subjected to physicochemical analysis, including the determination of its pH value, NAG enzyme activity, NAG-pH and carbon, nitrogen and phosphorus indices. Based on the analysis results, the improved substrate was precisely designed and formulated, with the following specific ratio: 60 kg of spoil heap soil, 2.5 kg of lime, 12 kg of riverbed sediment, 3 kg of yak manure and 36 g of inorganic fertilizer, providing data support and material basis for subsequent precise improvement.

[0047] (2) Terrain management and soil pretreatment: Physical pretreatment of the original soil, manual removal of obstacles such as large stones and gravel, and thorough mixing of soil from different sampling points to eliminate spatial heterogeneity and ensure the consistency and uniformity of the experimental matrix.

[0048] (3) Soil improvement: The lime, riverbed mud, yak manure and inorganic fertilizer organic composite matrix prepared in step (1) are mixed evenly with the pretreated soil to complete the targeted chemical improvement. Then, the improved matrix is ​​divided into standard pots of 10 cm × 10 cm × 10 cm to simulate micro-topography units and is kept stable at room temperature for 3 days to create a stable environment for plant planting and microbial inoculation.

[0049] (4) Functional microbial inoculation: Sulfate-reducing bacteria were inoculated via root irrigation. Three treatment groups were established: ① Blank control (inoculated with 10 mL of sterile culture medium); ② Pure bacteria treatment (inoculated with 10 mL of sterile culture medium). Desulfosporosinus acidophilic ③ Mixed bacterial treatment (inoculation with 10 mL) Example 1 Cold-resistant sulfate-reducing bacteria).

[0050] (5) Cold-resistant plant selection and habitat maintenance: Screening of ryegrass ( Perennial ryegrass ) and Leymus chinensis ( Elymus is swaying. s) Two types of cold-resistant plants with well-developed root systems and their hybrid combinations were used for cultivation. Seeds were disinfected with a 5% sodium hypochlorite solution, rinsed with sterile water, and soaked to promote germination. They were then planted at a density of 20 plants per pot (hybrid combinations were planted in a 1:1 ratio). After planting, the surface was covered with straw to retain warmth and moisture, and all pots were placed in a temperature-controlled environment of 10-15℃ for uniform cultivation to simulate the habitat of high-altitude cold regions and ensure normal plant growth.

[0051] According to the gravimetric method for the determination of water-soluble and acid-soluble sulfates in soil (HJ635-2012), the pH value and sulfate content of soil and surface water in the experimental area were monitored.

[0052] The results are as follows Figure 2 As shown. By Figure 2 It is known that inoculation with cold-resistant sulfate-reducing bacteria can significantly promote plant growth, with inoculation of cold-resistant sulfate-reducing bacteria groups showing the best effect. Furthermore, the SO4 content in soil inoculated with sulfate-reducing bacteria groups... 2- The content was reduced by 58.3%, which can effectively curb the generation of acid mine drainage (AMD) from the source and achieve source control of AMD.

[0053] Example 3 This invention provides an ecological restoration method for a high-altitude mining wasteland. The restoration site is a slope of the Jiama mining wasteland in Tibet (altitude 4661 m), and the restoration time is August 2025. The original soil conditions in this area are extremely harsh, with severe soil erosion, strong acidity, and high acidification potential. Acidification is still ongoing in some areas, and the soil contains excessive levels of heavy metals with strong toxic effects. The restoration area is 50 m². 2 The specific steps are as follows: 1.1 Site Survey and Quantification: Soil pH, NAG, NAG-pH, and carbon, nitrogen, and phosphorus content were measured to calculate the dosage of amendment materials and microbial agents. Analysis of the NAG index in the remediation area showed NAG to be 7.00 kg H2SO4 / t. Based on a 10 cm amendment depth, an estimate of 50 m was made. 2 The total amount of Ca(OH)2 required for remediation is 432 kg. The calculated dosage of the inoculant is 1 L / m³. 2 (Ensure ≥10 inoculations per square meter of soil) 8 CFU functional bacteria), 50 m 2 50 L is required. Analysis of the carbon, nitrogen, and phosphorus content in the soil of the remediation area indicates a deficiency level according to the grading standards; therefore, 150 kg / m² of organic composite matrix will be added. 2 (consuming 100 kg / m³ of cow dung) 2 The phosphorus content in cow dung is only moderate, requiring the addition of additional phosphate fertilizer. Inorganic phosphorus (600 g / m²) serves as a readily available phosphorus source.

[0054] The formula for calculating the amount of Ca(OH)2 used is as follows: (a) The net acid production (NAG) per ton of acidic soil is calculated as follows: Where m is the volume of sodium hydroxide standard solution consumed in the determination of NAG; w is the mass of the soil sample weighed in the determination of NAG; (b) The amount of Ca(OH)2 required to neutralize one ton of acidic soil: (c) Estimate the total amount of Ca(OH)2 required for the remediation area with area b and improvement depth a: Where b represents the area of ​​soil to be remediated; a represents the planned depth of soil improvement.

[0055] In summary, the experimental plot (50 m) 2 Soil amendment materials usage: 432 kg lime; 3.75 t organic composite substrate; 50 L compound microbial agent; 30 kg inorganic fertilizer.

[0056] 2. Terrain Improvement and Soil Pretreatment: Existing slopes are appropriately modified on a small scale, and waterlogged areas are backfilled to facilitate subsequent ecological restoration. In areas with many rocks and severe soil deficiency, nearby soil is used for covering. The topsoil is thoroughly tilled to a depth of 10 cm, and ridges are manually created. Walking paths between the ridges naturally form strip-shaped ditches that connect to the surrounding drainage ditches. Planting holes are arranged in a fish-scale pattern between the ditches. After land preparation, rainwater or artificial irrigation is used to allow toxic substances in the soil to settle and leach out, diluting the acidity of the topsoil.

[0057] Ditch specifications: 30 cm wide × 30 cm deep, with a spacing of 200 cm.

[0058] Fish scale pit specifications: 30 cm × 30 cm wide × 40 cm deep, with a spacing of 100 cm.

[0059] 3. Targeted Soil Improvement: After preparation, alkaline neutralizing materials and organic composite substrates are sown in the planting trenches to provide targeted soil improvement. This adjusts the soil pH to 6-8, increases soil organic matter content, reduces heavy metal toxicity, and improves the soil structure in the mining area. After sowing, the trenches are backfilled and gently compacted, then allowed to equilibrate for 3 days to ensure full contact between the improvement materials and the mine soil.

[0060] 4.4 Functional microbial inoculation: Dig trenches 8-12 cm deep on the surface of the targeted improved mining soil. Spray the cold-resistant sulfate-reducing bacterial solution prepared in Example 1 evenly into the trenches, backfill the trenches and gently compact them.

[0061] 5. Cold-resistant plant configuration and habitat maintenance: Based on the vegetation survey results of the Jiama gold and copper mine in Tibet, eight herbaceous plants were selected: *Leymus chinensis*, *Poa chinensis*, *Festuca amurensis*, *Lolium rupestris*, *Alternanthera philoxeroides*, *Taraxacum officinale*, *Festuca pulcherrima*, and *Cosmos bipinnatus* (Gesang flower, used as a landscape plant); and one shrub: *Hippophae rhamnoides*. The types and sowing amounts of the cold-resistant plants are shown in Tables 1 and 2.

[0062] Vegetation restoration process: Planting seedlings in nutrient bags → Covering with soil and seed bank, sowing seeds → Covering with shading → Irrigating to retain moisture, detailed as follows: 1) To improve plant survival rates, shrubs should ideally be purchased as seedlings 30-50 cm tall, often in nutrient bags. The roots must be firmly planted to ensure survival in the improved soil substrate. Use the "three-bury, two-tamp, one-lift" planting method. On the improved soil, plant at a density of 8 seedlings per m². 2 Plant shrub seedlings in bags at a certain density.

[0063] 2) Broadcast grass seeds and cover the soil with the seed bank. Herbaceous seeds should be sown at a rate of 20 g / m². 2 Sow the seeds at a density of mixed seeds. When sowing, gently rake the seeds into the soil with a fine-toothed rake to ensure shallow sowing without affecting the even distribution of the grass seeds.

[0064] 3) Irrigation and moisture retention: After planting, it is necessary to water the plants thoroughly to promote faster root growth and enhance their resistance.

[0065] 4) Cover the surface with crop straw to prevent moisture evaporation and soil compaction caused by rainfall and irrigation.

[0066] 5) Make holes (15-20 cm in diameter) according to the plant spacing and plant the shrub seedlings in the bags. After planting, seal and compact the area around the holes with fine soil.

[0067] 6) After the plants germinate and emerge, promptly release the seedlings through the broken film to avoid inhibiting their growth.

[0068] Steps 2) to 3) are to be completed within one day, and steps 4) to 5) are to be completed within one day.

[0069] Table 1. Herbaceous plants used for vegetation restoration Table 2. Shrubs used for vegetation restoration 6. Construction Period Maintenance and Sampling Testing: According to HJ 962-2018 "Determination of Soil pH Value by Potentiometric Method", HJ 704-2014 "Determination of Available Phosphorus in Soil by Sodium Bicarbonate Extraction-Molybdenum Antimony Spectrophotometric Method", and HJ 635-2012 "Determination of Water-Soluble and Acid-Soluble Sulfates in Soil by Gravimetric Method", the pH value, acidification index, and nutrient element content of the soil and surface water in the experimental area were monitored. The test results are shown in Table 3. The conditions of the experimental site before and after remediation are as follows: Figure 3 As shown.

[0070] Table 3 Changes in key indicators before and after restoration in the experimental area Table 3 shows that, compared with the data before remediation, the pH value of the soil in the experimental area increased from 4.5 to 8.9 after remediation, and the key acidifying factor SO4 increased. 2- The content of AMD decreased by 44.5% synchronously; the pH of surface water increased from 4.0 to 7.48, effectively curbing the formation of AMD at its source and achieving source control of AMD; the content of soil nutrients was significantly improved. In addition, vegetation survey results show that the vegetation coverage in this area is over 90%, and a self-sustaining, non-degrading stable vegetation system has been initially established. This also proves that the microbial inoculant compound scheme described in this invention can achieve good remediation results in other mining waste sites.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An ecological restoration method for abandoned mining sites in high-altitude and cold regions, characterized in that, Includes the following steps: (1) Site survey and quantification: Determine the physical and chemical properties of the soil and calculate the dosage of amendment materials and microbial agents; (2) Terrain improvement and soil pretreatment: trimming slopes, backfilling water-collecting pits, covering gravel areas with soil, and tilling; (3) Soil improvement: Apply alkaline materials and organic composite matrix; (4) Inoculation with functional microorganisms: Inoculate with cold-resistant sulfate-reducing bacteria; (5) Cold-resistant plant configuration and habitat maintenance; planting a three-dimensional grass-shrub community and covering it with straw and mulch; The cold-resistant sulfate-reducing bacteria were enriched and domesticated from the soil of the Jiama mining area in Tibet.

2. The ecological restoration method for high-altitude mining wasteland according to claim 1, characterized in that, The cold-resistant sulfate-reducing bacterial group includes *Desulfurized Bacillus*, *Desulfurized Saussurea*, and *Clostridium*.

3. The ecological restoration method for abandoned mining sites in high-altitude and cold regions according to claim 1, characterized in that, The cold-resistant sulfate-reducing bacterial community includes *Desulfurized Campylobacter* with an abundance percentage of 60-63%, *Clostridium* with an abundance percentage of 20-28%, and *Clostridium* with an abundance percentage of 10-15%.

4. The ecological restoration method for high-altitude mining wasteland according to claim 1, characterized in that, The method for enriching and acclimatizing the cold-resistant sulfate-reducing bacterial community includes the following steps: (1) Enrichment of cold-resistant sulfate-reducing bacteria: Soil samples were weighed and inoculated into modified Postgate liquid medium for primary anaerobic enrichment; (2) Low-temperature acclimatization of cold-resistant sulfate-reducing bacteria: When the culture medium in step (1) changes from clear to dark black or black precipitate, the bacterial solution is transferred to a modified Postgate liquid medium at 15°C and pH unchanged for continued culture. The transfer is repeated 6–7 times. Each time the culture temperature is reduced by 1°C until the culture temperature is 10°C.

5. The ecological restoration method for high-altitude mining wasteland according to claim 1, characterized in that, The alkaline material in step (3) is slaked lime; the formula for calculating the amount of slaked lime used is: (a) The net acid production (NAG) per ton of acidic soil is calculated as follows: Where m is the volume of sodium hydroxide standard solution consumed in the determination of NAG; w is the mass of the soil sample weighed in the determination of NAG; (b) The amount of Ca(OH)2 required to neutralize one ton of acidic soil: (c) Estimate the total amount of Ca(OH)2 required for the remediation area with area b and improvement depth a: Where b represents the area of ​​soil to be remediated; a represents the planned depth of soil improvement.

6. The ecological restoration method for abandoned mining sites in high-altitude and cold regions according to claim 1, characterized in that, The organic composite substrate in step (3) includes yak dung and riverbed sediment; the mass ratio of yak dung to riverbed sediment in the organic composite substrate is yak dung: riverbed sediment = 2:

1.

7. The ecological restoration method for high-altitude mining wasteland according to claim 1, characterized in that, The cold-resistant sulfate-reducing bacteria have a sulfate reduction rate of ≥70% at 10℃.

8. The ecological restoration method for abandoned mining sites in high-altitude and cold regions according to claim 1, characterized in that, The formula for calculating the dosage of the cold-resistant sulfate-reducing bacteria in step (4) is as follows: The target concentration is 1×10 8 - 1×10 10 CFU / kg, bacterial concentration 1×10 10 - 1×10 11 CFU / L, inoculation depth of 0.10 ~ 0.12 m.

9. The ecological restoration method for high-altitude mining wasteland according to claim 1, characterized in that, The grass-shrub three-dimensional community in step (5) includes a herbaceous layer and a shrub layer; the plants in the herbaceous layer include at least one of the following: *Leymus chinensis*, *Poa stenoptera*, *Festuca amurensis*, *Lycium chinense*, *Alternanthera philoxeroides*, *Taraxacum mongolicum*, *Euphorbia milii*, *Fragaria lobata*, *Leymus chinensis*, and *Rumex acetosa*; the plants in the shrub layer include at least one of the following: *Hippophae rhamnoides*, *Potentilla fruticosa*, *Rhododendron simsii*, and *Tamarix chinensis*.

10. The application of the ecological restoration method for high-altitude mining wasteland according to any one of claims 1 to 9 in the restoration of high-altitude mining wasteland.

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