Ecological restoration method suitable for tailings ponds in northern China

Abstract

The invention relates to the technical field of establishment and planting of zoysia japonica grass stem sodded belts, in particular to an ecological restoration method suitable for tailings ponds in northern China. Comprising the following steps: grass stem preparation, planting and maintenance of a sodded strip, and ecological restoration of the tailing pond. According to the method, zoysia japonica bark resources, soil resources and water resources can be saved, and meanwhile the method has the advantages that plant growth is lasting and stable, the remediation cost is low, the remediation effect is remarkable, and pollution to the environment is avoided. When the method is applied to ecological restoration engineering of various severe environments, remarkable environmental benefits can be obtained.

Description

Technical Field

[0001] The invention relates to a technology for establishing a Japanese Zoysia grass stem vegetation belt, and in particular to a technology for ecological restoration of tailings ponds by combining agricultural solid waste with a Japanese Zoysia grass stem vegetation belt, which is suitable for the temperate zone in northern my country. Background Art

[0002] The root system of woody plants will have a serious impact on the tailings dam, so only herbaceous plants can be used for ecological restoration. Zoysia japonica has well-developed stolons and rhizomes, and is extremely resistant to stress. It has broad prospects for ecological restoration in abandoned mines, saline-alkali land, sandy land and heavy metal contaminated areas. Tailings ponds are mostly sites where the content of heavy metals or organic pollutants exceeds the standard. Directly cutting the stems of Japanese Zoysia japonica into sections and planting them on the tailings pond is easy to be poisoned by pollutants due to the weak stress resistance of the stems during survival. In addition, it requires a lot of water, nutrients and other strict maintenance conditions, which can easily lead to the failure of the restoration project. Directly laying Zoysia japonica turf can solve the above problems, but due to the limited resources of Zoysia japonica turf and the restrictions of national policies, this method is difficult to implement.

[0003] How to solve the above technical difficulties and use Zoysia japonica stem propagation method to carry out ecological restoration of tailings land is an important issue. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a new technology for repairing tailings ponds by making Zoysia japonica stem vegetation belts using agricultural solid waste. The technology of the present invention can be applied to ecological restoration projects in various harsh environments to obtain significant environmental benefits.

[0005] To achieve the above object, the technical solution of the present invention is as follows: An ecological restoration method suitable for tailings ponds in northern China, comprising the following steps:

[0006] 1. Preparation of grass stems:

[0007] Take a number of zoysia grass stems with crisscrossing stolons and rhizomes, soak them in water, and then perform cutting and rooting treatments;

[0008] (II) Planting and maintenance of vegetation belts

[0009] 1) Selection of vegetation belt breeding sites: select idle wasteland or idle cement ground with convenient water source and close to the tailings pond to be repaired;

[0010] 2) Laying of vegetation belt: Lay a layer of geotextile with a thickness of 3-5 mm on the selected open ground, and lay a layer of fine sand with a thickness of 0.3-0.5 cm on the geotextile. Lay a degradable non-woven fabric with a thickness of 0.5 mm, a width of 1-1.5 meters, and a pore size of 0.1 mm on the surface of the fine sand, and cover it with a layer of a mixture of raw sawdust and coconut bran, and then cover it with a layer of non-woven fabric with a thickness of 0.2 mm, a pore size of 0.2 mm and the same width;

[0011] 3) Grass stem laying: Sprinkle the prepared grass stem segments on the surface of the non-woven fabric, with a spacing of about 5 cm between the grass stem segments, and plant 0.5 kg of grass stem segments per square meter on average. Cover the grass stem surface with a mixture of sawdust, fine sand and coconut bran to a thickness of 0.5 cm; roll it once to make the grass stem and the covering tightly combined to avoid protrusions, cover the rolled surface with a mixture of sawdust, fine sand and coconut bran to a thickness of 0.5 cm, roll it once, and water and fertilize.

[0012] 4) Making of vegetation tape roll: According to the method described in 3), the coverage of the Zoysia japonica stem vegetation tape can reach 85%-95% in 50-60 days. At this time, the Zoysia japonica vegetation tape has been formed, and the roots can pass through the two layers of non-woven fabrics and take root in the sand layer above the geotextile. The vegetation tape is rolled up from the bottom non-woven fabric to form a vegetation tape roll;

[0013] 3. Ecological restoration of tailings ponds

[0014] 1) Site debris removal: Remove stones and other debris on the surface of the tailings pond. Roughly level the site surface while keeping the original slope of the tailings pond unchanged. Mix agricultural solid waste coconut bran and raw rice husk in a ratio of 2:1 and spread it on the soil surface of the tailings pond to be repaired. The thickness is 5-6 cm and the roller weighing about 150 kg is used for rolling.

[0015] 2) Time to lay the vegetation tape roll: Planting should be done during the rainy season from June to August in northern regions;

[0016] 3) Method for laying vegetation tape rolls: Cut the vegetation tape rolls longitudinally to make strip vegetation tapes, lay the strip vegetation tapes on the substrate surface in a direction parallel to the contour lines at a certain interval, and roll them;

[0017] 4) Stem collection: In early October each year, cut off the runners growing between the two vegetation belts, shake off the soil, collect the runners, dry them, and transport them to a professional heavy metal disposal company. First, burn them in an incinerator and then treat the ash. After removing the grass stems, rake the topsoil of the interval belt flat, which is conducive to the extension and collection of runners the following year.

[0018] Furthermore, in the above-mentioned ecological restoration method suitable for tailings ponds in northern regions, in step (a), from mid-April to mid-May each year, the lawn of the Zoysia japonica breeding base is pruned close to the ground, all the above-ground parts are cut off, and the topsoil with a thickness of 5 cm is removed by a lawn mower, and the soil blocks on the turf are knocked off to obtain a network of grass stems with multiple runners and rhizomes crisscrossing each other.

[0019] Furthermore, in the above-mentioned ecological restoration method suitable for tailings ponds in northern regions, in step (i), the immersion treatment is: soaking the stems of the net grass in tap water for 24 hours, and changing the water every 8 hours.

[0020] Furthermore, the above-mentioned ecological restoration method suitable for tailings ponds in northern regions, in step (a), the sectioning treatment is: taking out the net-like grass stems, removing the fibrous roots on the grass stem nodes, and then using a cutting machine to cut them vertically and horizontally, with a cutting interval of 3 cm, to form countless grass stem segments, each with 1-2 nodes.

[0021] Furthermore, in the above-mentioned ecological restoration method suitable for tailings ponds in northern regions, in step (a), the rooting treatment is as follows: take a number of aloe leaves, use a juicer to crush the aloe leaves to extract aloe juice, make a mixture of aloe juice and water in a ratio of 1:1000, put the grass stem segments into the mixture and soak them for 1-1.5 hours, then take them out and prepare to plant them in the vegetation belt.

[0022] Furthermore, in the above ecological restoration method for tailings ponds in northern regions, in step (ii), 2), the mass ratio of raw sawdust to coconut bran is 1:1.

[0023] Furthermore, in the above-mentioned ecological restoration method for tailings ponds in northern regions, in step (ii), 3), the mass ratio of sawdust, fine sand and coconut bran is 1:1:2.

[0024] Furthermore, in the above-mentioned ecological restoration method for tailings ponds in northern regions, in step (ii), 3), the watering is carried out during the period of rooting and survival of the grass stems, i.e., the first half of the month, watering once in the morning and evening every day, and then watering once every 3-4 days; the fertilization is the application of urea fertilizer once every 10 days starting half a month after the grass stems are planted, and the amount of fertilizer applied each time is 6-8 grams / square meter.

[0025] Furthermore, in the above-mentioned ecological restoration method for tailings ponds in northern regions, in step (iii), 3), the width of the strip vegetation belt is 20-30 cm, and a spacing zone of 35-40 cm is retained between two adjacent vegetation belts.

[0026] The beneficial effects of the present invention are:

[0027] 1. Save Zoysia grass turf resources: Through the Zoysia grass segment propagation method, 1 square meter of Zoysia grass lawn can reproduce 30-40 square meters of vegetation belt lawn, thus saving a lot of Zoysia grass lawn resources.

[0028] 2. Save soil resources: Tailings ponds are mostly sites with excessive heavy metal or organic pollutant content. Due to severe pollution, plants cannot grow normally. The usual ecological restoration method requires the use of a large amount of farmland soil for soil improvement and then plant restoration. The technology of the present invention does not require farmland soil, and the method of using agricultural solid waste to propagate grass stem vegetation belts can achieve good ecological restoration effects. Therefore, a large amount of soil resources are saved.

[0029] 3. Save water resources: Geotextiles, raw sawdust, coconut bran and raw rice husks used in the construction of vegetation belts and the restoration of tailings ponds all have strong water-holding capacity, which reduces water evaporation and loss in the construction of vegetation belts; using the water-holding capacity of the grass stem vegetation belt planted in the tailings pond in the rainy season and the coconut bran and raw rice husk mixture matrix with a thickness of 5-6 cm can overcome the problem of water shortage, which is one of the key limiting factors for plant restoration in tailings ponds. Therefore, a large amount of water resources can be saved.

[0030] 4. The grass stems take root quickly and the lawn is formed quickly: soaking the grass stems in a mixture of aloe vera juice and water can help the grass stems absorb the nutrients needed for rooting directly, so that they can take root quickly and grow quickly. This is the result of the comparison of microscopic and macroscopic experimental observations in the early stage of the experiment. Therefore, the grass stems take root quickly and the lawn is formed quickly.

[0031] 5. Long-lasting and stable plant growth: The main reason affecting the ecological restoration effect of the tailings pond is the serious pollution of heavy metals or organic pollutants. In the previous ecological restoration methods, plants can grow normally in the early stage of restoration due to the improvement of the surface layer of the soil. However, after a period of time, as the plant roots take root deeply, the pollution factors will aggravate the stress on the restoration plants, leading to the ultimate failure of the restoration. The raw sawdust, coconut bran and raw rice husks used in the technology of the present invention will slowly ferment and decompose into organic matter during the subsequent growth of Zoysia japonica. With the rainfall, the solution will gradually penetrate into the original soil of the deep tailings pond, which not only improves the physical properties of the soil, improves the air permeability and nutrition of the soil, but also, most importantly, can form macromolecular complexes with heavy metals that cannot be absorbed by plants, degrade organic pollutants, and thus reduce the stress on plants. Therefore, the restoration effect is long-lasting and stable. The technology of the present invention has been applied in a copper mine tailings pond in Liaoning for two years, and the restoration effect is very good. The cadmium content of the 25 cm soil on the surface of the tailings pond before restoration was 15 mg kg -1 , lead content is 280mg·kg -1 One year after the repair, the cadmium content of the tailings pond was 8.5 mg kg -1 , lead content is 130mg·kg -1, the cadmium content was 4.8 mg kg after two years of restoration -1 , lead content is 25mg·kg -1 .

[0032] 6. Low cost of restoration: The substrates used in the technology of the present invention are all agricultural solid waste, which has a low purchase cost and realizes the recycling of waste. When collecting the stems of Zoysia japonica enriched with pollutants, the vegetation belt lawn planted in the tailings pond is not broken, so it can be used permanently, so the cost is extremely low.

[0033] 7. Significant restoration effect: Since Zoysia has well-developed stolons and rhizomes, according to my previous invention patent ZL 2022 1 1172356.4, the stolons and rhizomes of Zoysia can absorb a large amount of pollution factors. Therefore, the restoration effect is significant.

[0034] 8. No pollution to the environment: Non-woven fabric is a new type of bio-based material that is degradable, friendly to the ecological environment, and will not produce chemical toxicity, so it will not pollute the environment.

[0035] 9. It is conducive to the rooting of grass stems in the vegetation belt: the pore size of the upper non-woven fabric is 0.2 mm, and the pore size of the lower non-woven fabric is 0.1 mm. It not only facilitates the root system to take root, but also effectively avoids the loss of the vegetation belt matrix.

[0036] 10. In-situ restoration: According to national regulations, one of the principles for ecological restoration after the tailings pond is that no major disturbance is allowed. The technology of the present invention does not disturb the tailings pond, which complies with relevant regulations.

[0037] 11. It is convenient to collect grass stems and grass stem roots: A 5-6 cm thick matrix layer of a mixture of coconut bran and raw rice husk is laid at the interval between the two vegetation belts. Since the matrix layer made of coconut bran and raw rice husk is very loose, it is very convenient to remove the soil from the stolons and their roots extending above the matrix layer. They can be collected by shaking. DETAILED DESCRIPTION

[0038] Example 1

[0039] 1. Preparation of grass stems

[0040] 1. Time and method of collecting grass stems: The collection time is from mid-April to mid-May every year. Collection method: The lawn of the Zoysia grass breeding base is built close to the ground, and all the above-ground parts are cut off. Use a lawn mower to remove the turf with a thickness of 5 cm. Knock off the soil on the turf to obtain a network of grass stems with multiple runners and rhizomes crisscrossing each other.

[0041] 2. Soaking the grass stems in water: Soak the mesh grass stems in tap water for 24 hours, changing the water every 8 hours.

[0042] 3. Sectioning: Take out the mesh grass stems, cut off the fibrous roots on the grass stem nodes, and then use a cutting machine to cut vertically and horizontally with a cutting interval of 3 cm. This will form countless grass stem segments, each with 1-2 nodes.

[0043] 4. Rooting treatment: Take some aloe leaves, use a juicer to crush the aloe leaves to extract aloe juice, make a mixture of aloe juice and water in a ratio of 1:1000, put the grass stem segment into the mixture and soak it for 1-1.5 hours, then take it out and prepare to plant it in the vegetation belt.

[0044] 2. Planting and maintenance of vegetation belts

[0045] 1. Selection of breeding sites for vegetation belts: Select idle wasteland or idle cement ground that can provide convenient water sources and is close to the tailings pond to be repaired.

[0046] 2. Laying of vegetation belt: Lay a layer of geotextile with a thickness of 3-5 mm on the selected open ground, and then lay a layer of fine sand with a thickness of 0.3-0.5 cm on the geotextile. Lay a degradable non-woven fabric with a thickness of 0.5 mm, a width of 1-1.5 meters, and a pore size of 0.1 mm on the surface of the fine sand, and cover it with a layer of a mixture of raw sawdust and coconut bran in a ratio of 1:1, and then cover it with a layer of non-woven fabric with a thickness of 0.2 mm, a pore size of 0.2 mm and the same width.

[0047] 3. Grass stem laying: Sprinkle the prepared grass stem segments on the surface of the non-woven fabric, with a spacing of about 5 cm between the grass stem segments. On average, 0.5 kg of grass stem segments are laid per square meter.

[0048] 4. Covering the grass stems: Cover the surface of the grass stems with a mixture of sawdust, fine sand and coconut bran in a ratio of 1:1:2, with a thickness of about 0.5.

[0049] 5. Pressing: Use a 50 kg roller to press once to make the grass stems and covering material tightly combined to avoid protrusion.

[0050] 6. Covering: Cover the compacted surface with a mixture of sawdust, fine sand and coconut bran in a ratio of 1:1:2, with a thickness of about 0.5 cm.

[0051] 7. Pressing: Use a 50 kg roller to press once.

[0052] 8. Watering: During the first half month of the grass stem rooting period, water once in the morning and evening every day to keep the grass stem vegetation layer moist. After that, water once every 3-4 days.

[0053] 9. Fertilization: Apply urea fertilizer once every 10 days starting half a month after the grass stems are planted, with each application amount of 6-8 grams per square meter.

[0054] 10. Production of vegetation tape roll: According to the above method, the coverage of the Zoysia grass stem vegetation tape can reach 85%-95% in about 50-60 days. At this time, the Zoysia grass vegetation tape has been formed, and the roots can pass through the two layers of non-woven fabrics and take root in the sand layer above the geotextile. Roll up the vegetation tape from the bottom non-woven fabric to form a vegetation tape roll. The bottom geotextile and sand are retained and recycled as the base for the next batch of vegetation tapes.

[0055] 3. Ecological restoration of tailings ponds

[0056] 1. Site debris removal: remove stones and other debris on the surface of the tailings pond.

[0057] 2. Site leveling: On the premise that the original tailings pond slope remains unchanged, the site surface is roughly leveled.

[0058] 3. Laying the substrate: Mix agricultural solid waste coconut bran and raw rice husk in a ratio of 2:1 and spread it on the soil surface of the tailings pond to be repaired with a thickness of 5-6 cm. Use a roller weighing about 150 kg to roll it once.

[0059] 4. Time to lay the vegetation tape roll: Planting should be done during the rainy season from June to August in northern regions. This way, watering is not required.

[0060] 5. Method of laying vegetation tape rolls: Cut the vegetation tape rolls longitudinally, leaving a width of about 20-30 cm, to make strip vegetation tapes. Lay the strip vegetation tapes on the substrate surface in a direction parallel to the contour lines at a certain interval, and keep a spacing of 35-40 cm between two adjacent vegetation tape strips.

[0061] 6. Pressing: Use a 50 kg roller to press once.

[0062] 7. Collecting stems: In early October every year, cut off the runners growing between the gaps of the two vegetation belts, shake off the soil, collect the runners and dry them.

[0063] 8. Treatment: Transport to a professional heavy metal disposal company, first incinerate in an incinerator and then treat the ash.

[0064] 9. Treatment of the spacing strips: After removing the grass stems, rake the surface soil of the spacing strips flat to facilitate the extension and collection of the runners in the next year.

Claims

1. An ecological restoration method suitable for tailings ponds in northern China, characterized in that: The steps include:

1. Preparation of grass stems: Take a number of zoysia grass stems with crisscrossing stolons and rhizomes, soak them in water, and then perform cutting and rooting treatments; (II) Planting and maintenance of vegetation belts 1) Selection of vegetation belt breeding sites: select idle wasteland or idle cement ground with convenient water source and close to the tailings pond to be repaired; 2) Laying of vegetation belt: Lay a layer of geotextile with a thickness of 3-5 mm on the selected open ground, and lay a layer of fine sand with a thickness of 0.3-0.5 cm on the geotextile. Lay a degradable non-woven fabric with a thickness of 0.5 mm, a width of 1-1.5 meters, and a pore size of 0.1 mm on the surface of the fine sand, and cover it with a layer of a mixture of raw sawdust and coconut bran, and then cover it with a layer of non-woven fabric with a thickness of 0.2 mm, a pore size of 0.2 mm and the same width; 3) Grass stem laying: Sprinkle the prepared grass stem segments on the surface of the non-woven fabric, with a spacing of about 5 cm between the grass stem segments, and plant 0.5 kg of grass stem segments per square meter on average. Cover the grass stem surface with a mixture of sawdust, fine sand and coconut bran to a thickness of 0.5 cm; roll it once to make the grass stem and the covering tightly combined to avoid protrusions, cover the rolled surface with a mixture of sawdust, fine sand and coconut bran to a thickness of 0.5 cm, roll it once, and water and fertilize. 4) Making of vegetation tape roll: According to the method described in 3), the coverage of the Zoysia japonica stem vegetation tape can reach 85%-95% in 50-60 days. At this time, the Zoysia japonica vegetation tape has been formed, and the roots can pass through the two layers of non-woven fabrics and take root in the sand layer above the geotextile. The vegetation tape is rolled up from the bottom non-woven fabric to form a vegetation tape roll; 3. Ecological restoration of tailings ponds 1) Site debris removal: Remove stones and other debris on the surface of the tailings pond. Roughly level the site surface while keeping the original slope of the tailings pond unchanged. Mix agricultural solid waste coconut bran and raw rice husk in a ratio of 2:1 and spread it on the soil surface of the tailings pond to be repaired. The thickness is 5-6 cm and the roller weighing about 150 kg is used for rolling. 2) Time to lay the vegetation tape roll: Planting should be done during the rainy season from June to August in northern regions; 3) Method for laying vegetation tape rolls: Cut the vegetation tape rolls longitudinally to make strip vegetation tapes, lay the strip vegetation tapes on the substrate surface in a direction parallel to the contour lines at a certain interval, and roll them; 4) Stem collection: In early October each year, cut off the runners growing between the two vegetation belts, shake off the soil, collect the runners, dry them, and transport them to a professional heavy metal disposal company. First, burn them in an incinerator and then treat the ash. After removing the grass stems, rake the topsoil of the interval belt flat, which is conducive to the extension and collection of runners the following year.

2. The ecological restoration method for tailings ponds in northern China according to claim 1, characterized in that: In step (i), from mid-April to mid-May each year, the lawn of the Zoysia japonica breeding base is built close to the ground, all the above-ground parts are cut off, and the turf with a surface soil thickness of 5 cm is removed by a lawn mower, and the soil blocks on the turf are knocked off to obtain a network of grass stems with multiple stolons and rhizomes crisscrossing each other.

3. The ecological restoration method for tailings ponds in northern China according to claim 1, characterized in that: In step (a), the soaking treatment is as follows: soaking the stems of the net grass in tap water for 24 hours, and changing the water every 8 hours.

4. The ecological restoration method for tailings ponds in northern China according to claim 1, characterized in that: In step (a), the sectioning process is as follows: the net-shaped grass stems are taken out, the fibrous roots on the grass stem sections are cut off, and then the grass stems are cut vertically and horizontally by a cutting machine with a cutting interval of 3 cm to form numerous grass stem sections, each section having 1-2 sections.

5. The ecological restoration method for tailings ponds in northern China according to claim 1, characterized in that: In step (i), the rooting treatment is as follows: take a number of aloe leaves, crush the aloe leaves with a juicer to extract aloe juice, prepare a mixture of aloe juice and water in a ratio of 1:1000, soak the grass stem segments in the mixture for 1-1.5 hours, then take them out and prepare to plant them in the vegetation belt.

6. The ecological restoration method for tailings ponds in northern China according to claim 1, characterized in that: In step (ii), 2), the mass ratio of raw sawdust to coconut bran is 1:

1.

7. The ecological restoration method for tailings ponds in northern China according to claim 1, characterized in that: In step (ii), 3), the mass ratio of sawdust, fine sand and coconut bran is 1:1:

2.

8. The ecological restoration method for tailings ponds in northern China according to claim 1, characterized in that: In step (ii), 3), the watering is done during the first half month of the grass stem rooting period, watering once in the morning and evening every day, and then watering once every 3-4 days; the fertilization is done by applying urea fertilizer once every 10 days starting half a month after the grass stems are planted, and the amount of fertilizer applied each time is 6-8 grams per square meter.

9. The ecological restoration method for tailings ponds in northern China according to claim 1, characterized in that: In step (iii), 3), the width of the strip vegetation belt is 20-30 cm, and a spacing of 35-40 cm is reserved between two adjacent vegetation belts.