Selenium-containing phytoremediation enhancer as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of soil pollution phytoremediation enhancement, and particularly relates to a selenium-containing phytoremediation enhancer as well as a preparation method and application thereof, and the enhancer is fermentation liquor prepared by fermenting selenium-rich rice straws. The selenium-containing phytoremediation enhancer disclosed by the invention is a beneficial element capable of promoting the growth and development of plants, is easily dissolved in water and can be efficiently absorbed by the plants; the preparation method of the selenium-containing phytoremediation enhancer is simple and easy to implement, the emission of agricultural wastes is reduced by recycling selenium-rich straws, and the environmental pressure is relieved; when the selenium-containing phytoremediation enhancer is applied, the remediation efficiency is high, the cost is low, the phytoremediation enhancer has no toxic effect on plants and no environmental risk, and the selenium-containing phytoremediation enhancer has important significance on enhancing soil heavy metal phytoremediation and promoting growth of the soil heavy metal phytoremediation enhancer.

Description

Technical Field

[0001] The present invention belongs to the technical field of soil pollution phytoremediation enhancement, and in particular relates to a selenium-containing phytoremediation enhancer and a preparation method and application thereof. Background Art

[0002] Soil is the foundation of green and functional agriculture and a fragile environmental resource within the ecosystem. Poor soil conservation and management can lead to soil pollution and reduced soil fertility. With the rapid development of global industrialization, human-induced soil pollution is increasing, with heavy metal pollution being a particular concern. Heavy metals in soil can easily accumulate in plants, animals, and humans through the food chain, posing a serious threat to human health.

[0003] Arsenic contamination is an urgent environmental issue. Current methods for remediating arsenic-contaminated soil include physical, chemical, and biological remediation. Each method has its own advantages and disadvantages. Phytoremediation is an effective approach for environmental protection, as it can permanently remove soil contaminants while preserving soil arable properties. However, phytoremediation suffers from a long remediation cycle. Therefore, it is necessary to develop efficient and intensified technologies to reduce this cycle and facilitate its widespread application.

[0004] Numerous studies have reported on the enhanced effects of various enhancers on phytoremediation, but most have been limited to hydroponic experiments, lacking actual soil culture or field validation trials. Given that my country is a major agricultural country, rice harvesting generates a large amount of straw waste each year. Efficient straw resource utilization often focuses on fertilizer and energy production, while research on the production of phytoremediation enhancers from rice straw is limited.

[0005] Chinese patent CN111482453A discloses a method for remediating heavy metal-contaminated soil using a combination of plants and fungi. Specifically, it discloses that fungi and straw are combined to enhance the adsorption of heavy metals by plants. However, the arsenic absorption effect achieved by the combination of ordinary straw and microorganisms in the patent document still has room for improvement.

[0006] Selenium-rich agriculture is developing rapidly in my country, but research on integrating the resource utilization of selenium-rich rice straw with environmental protection is limited. Therefore, developing technologies and measures to utilize selenium-rich rice straw to produce phytoremediation enhancers is of great significance for remediating heavy metal-contaminated soils, improving soil fertility, and contributing to human health. Summary of the Invention

[0007] The present application aims to provide a selenium-containing plant remediation enhancer, a preparation method and application thereof, to solve the problem of insufficient research on plant remediation enhancers for existing actual arsenic contaminated sites, and to provide a selenium-containing plant remediation enhancer for remediation of arsenic contaminated soil and improvement of soil fertility, a preparation method and application thereof.

[0008] To achieve the above-mentioned purpose, the present application provides the following solutions:

[0009] A selenium-containing plant remediation enhancer, the enhancer being a fermentation liquor prepared from selenium-enriched rice straw, the fermentation liquor containing effective selenium, organic acid, nitrogen, phosphorus and potassium nutrient elements, and organic matter.

[0010] Preferably, the selenium content of the selenium-enriched rice straw is 0.1-0.9 mg / kg.

[0011] Preferably, the selenium content of the fermentation liquor is 0.02-0.05 mg / kg.

[0012] A preparation method of a selenium-containing plant remediation enhancer, comprising the following steps:

[0013] S1, collecting selenium-enriched straw: collecting selenium-enriched rice straw with a selenium content of 0.1-0.9 mg / kg and placing it in a cool and dry place for natural air drying;

[0014] S2, preparing pretreated raw materials: cutting and crushing the selenium-enriched straw raw materials by using a cutting machine to obtain pretreated raw materials;

[0015] S3, fermentation: preparing pretreated raw materials into raw materials before fermentation, wetting them with water, and then fermenting to obtain a fermentation liquor.

[0016] Preferably, in the S3 step, the solid-liquid ratio of the wetted raw materials is 0.7:1, the fermentation time is 45-60 days, and the raw materials are stirred at least once during the fermentation.

[0017] Preferably, the S3 step comprises mixing the pretreated raw materials with soil to prepare raw materials before fermentation.

[0018] Preferably, the S3 step comprises mixing the pretreated raw materials with a microbial agent, and then mixing the mixed product with soil to prepare raw materials before fermentation.

[0019] Preferably, the microbial agent is a mixture of Bacillus subtilis and Candida utilis, and the ratio of Bacillus subtilis to Candida utilis is 1:1.

[0020] A selenium-containing plant remediation enhancer for improving the soil remediation capacity of plants with heavy metal enrichment and improving soil fertility.

[0021] Preferably, the method comprises the following steps:

[0022] S1. Collect surface soil from heavy metal contaminated areas;

[0023] S2. Add a fortifier to the soil to supplement the selenium source, which is Sigma-Aldrich S0882 (>95%) sodium selenate, and balance ripen;

[0024] S3. Plant plants that have adsorption effects on heavy metals in the balanced and mature soil to complete the absorption of heavy metals in the soil.

[0025] Compared with the prior art, the present invention has the following advantages and technical effects:

[0026] The selenium-containing plant remediation enhancer of the present invention is a beneficial element that promotes plant growth and development, is easily soluble in water, and can be efficiently absorbed by plants. The preparation method of the selenium-containing plant remediation enhancer is simple and easy, and the discharge of agricultural waste is reduced by recycling selenium-rich straw, thereby alleviating environmental pressure. When the selenium-containing plant remediation enhancer is used, the remediation efficiency is high, the cost is low, it has no toxic effect on plants, and has no environmental risks, and is of great significance for enhancing the remediation of soil heavy metal plants and promoting their growth. DETAILED DESCRIPTION

[0027] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0028] Example 1:

[0029] This embodiment discloses a selenium-containing phytoremediation method, which specifically comprises the following steps:

[0030] S1. Collection of selenium-rich rice straw: Selenium-rich rice straw was collected in Binyang, Pumiao, Hengxian, and Jinde, Guangxi. The straw was placed in a cool, dry place and air-dried. The samples were digested with HNO3-H2O2 (USEPA Method 3050B) and the selenium content of the straw was determined by ICP-MS as shown in Table 1:

[0031] Among them, two types of selenium-rich straw were collected in Binyang, Guangxi, with selenium contents of 0.96 mg / kg and 0.47 mg / kg respectively.

[0032] A selenium-rich straw was collected from Pumiao, with a selenium content of 0.76 mg / kg.

[0033] Two types of selenium-rich straw were collected in Hengxian County, with selenium contents of 0.30 mg / kg and 0.25 mg / kg respectively.

[0034] Jinde collected a selenium-rich straw with a selenium content of 0.28 mg / kg.

[0035] S2. Preparing pretreated raw materials: using a cutting machine to cut the selenium-rich straw raw materials, the crushed selenium-rich straw is 2-5 cm in length, and then using a grinder to crush the pretreated selenium-rich straw, sieving it through a 10-mesh sieve, and taking the sieved crushed material for later use;

[0036] S3. Matured Selenium-enriched Straw: Surface soil was collected from an arsenic-contaminated area in Nanning, Guangxi. The soil was air-dried, crushed, and passed through a 20-mesh sieve. Crushed selenium-enriched straw was added at a ratio of 18 g of pre-treated raw material (crushed selenium-enriched straw) per kilogram of soil. Sodium selenate, a selenium supplement, was added to replenish the selenium content to 100 μg / kg. The soil was matured for 30 days to allow for full interaction between microorganisms, organic matter, selenium, and other nutrients in the soil, achieving a state of chemical stability and optimized biological activity, thereby creating suitable conditions for subsequent phytoremediation.

[0037] S4. Transplanting tall centipede grass: Transplant centipede grass 15-20 cm high;

[0038] S5. Setting up replicate groups: setting up three replicate groups for the above steps, and then planting the tall centipede grass for 45 days;

[0039] S6. Determination of the selenium and arsenic contents in soil and scolopendra: After the samples were treated with the HNO3-H2O2 (USEPA Method 3050B) digestion method, ICP-MS determined that the effective selenium content in the soil was 25.40-44.87 mg / kg (effective selenium content refers to the content of selenium forms in the soil that are easily absorbed by plant roots, such as water-soluble, exchangeable, and carbonate-bound forms), the selenium content in scolopendra leaves was 20.25-42.60 mg / kg, the arsenic content in the leaves was 6.88-14.08 mg / kg, and the biomass of scolopendra was 8.27-15.90 g (biomass refers to the average fresh weight of a single scolopendra plant).

[0040] Among them, the centipede grass seedling cultivation process and conditions used in this embodiment are: sowing mature centipede grass spores on the surface of the culture medium, controlling the temperature, humidity and light intensity, and after the seedlings grow to 2-3 cm, transplanting the seedlings into pots until they grow to 15-20 cm, and then they can be used for repair.

[0041] The culture medium is composed of nutrient soil and vermiculite, and the ratio of nutrient soil to vermiculite is 2:1.

[0042] During the culture process, the temperature was controlled at 26-28°C, the humidity was 60-70%, and the light intensity was 350 μmol / m 2 ·s.

[0043] The arsenic-contaminated soil collected during the process of maturing selenium-rich straw came from Heng County, Nanning City, Guangxi Province (N22°45′40″, E109°16′38″). It is arsenic-contaminated paddy soil. The physical and chemical properties of the soil are as follows: the measured pH is 5.21, the total nitrogen content is 1.26 g / kg, the total phosphorus content is 0.45 g / kg, the total potassium content is 3.19 g / kg, the organic matter content is 25.75 g / kg, and the total arsenic content is 81.07 mg / kg.

[0044] Table 1: Straw selenium content, soil available selenium content, leaf selenium and arsenic content, and biomass of the straw raw material treatment group in Example 1

[0045]

[0046] Example 2:

[0047] The difference between this embodiment and the first embodiment is that a selenium-containing phytoremediation enhancer and a phytoremediation method thereof are provided, and the steps include:

[0048] S1. Collection of selenium-rich rice straw: Selenium-rich rice straw was collected in Binyang, Pumiao, Hengxian, and Jinde, Guangxi. The straw was air-dried in a cool, dry place. The samples were digested with HNO3-H2O2 (USEPA Method 3050B), and the selenium content of the straw was determined by ICP-MS as shown in Table 2.

[0049] S2. Preparing pretreated raw materials: using a cutting machine to cut the selenium-rich straw raw materials into 2-5 cm lengths;

[0050] S3, fermentation: 25g of cut selenium-rich straw was mixed evenly with 18g of soil, fully moistened, and fermented for 45 days, stirring three times during the fermentation period to ensure a solid-liquid ratio of 0.7:1 and a selenium content of 0.02-0.05mg / kg;

[0051] S4. Matured selenium-enriched straw: Surface soil was collected from an arsenic-contaminated area in Nanning, Guangxi. The soil was air-dried, crushed, and passed through a 20-mesh sieve. 75 g of pretreated raw material (fermented selenium-enriched straw) was added to the soil per kilogram of soil. Selenium was supplemented with Sigma-Aldrich S0882 (>95%) sodium selenate to a selenium content of 100 μg / kg. The soil was matured for 30 days to allow for full interaction between microorganisms, organic matter, selenium, and other nutrients in the soil, achieving a state of chemical stability and optimized biological activity, thereby creating suitable conditions for subsequent phytoremediation.

[0052] S5. Transplanting tall centipede grass: Transplant centipede grass 15-20 cm high;

[0053] S6. Setting up replicate groups: setting up three replicate groups for the above steps, and then planting the tall centipede grass for 60 days;

[0054] S7. Determination of selenium and arsenic contents in soil and centipede grass: After the samples were treated with HNO3-H2O2 (USEPA Method 3050B) digestion method, ICP-MS determined that the effective selenium content in the soil was 39.67-76.27 mg / kg, the selenium content in centipede grass leaves was 34.90-53.42 mg / kg, the arsenic content in the leaves was 4.33-13.65 mg / kg, and the centipede grass biomass was 10.07-20.97 g.

[0055] Table 2: Straw selenium content, soil available selenium content, leaf selenium and arsenic content, and biomass of the straw fermentation liquid treatment group in Example 2

[0056]

[0057] Example 3:

[0058] Compared with the second embodiment, this embodiment differs in that the steps include:

[0059] S1. Collection of selenium-rich rice straw: Selenium-rich rice straw was collected in Binyang, Pumiao, Hengxian, and Jinde, Guangxi. The straw was air-dried in a cool, dry place. The samples were digested with HNO3-H2O2 (USEPA Method 3050B), and the selenium content of the straw was determined by ICP-MS as shown in Table 3.

[0060] S2. Preparing pretreated raw materials: using a cutting machine to cut the selenium-rich straw raw materials into 2-5 cm lengths;

[0061] S3, fermentation: take 25g of cut selenium-rich straw and 25g of Bacillus subtilis and Candida utilis (1:1) and mix them in a ratio of 1:1. Then mix the mixed product with 18g of soil and fully moisten it. The fermentation time is 50 days, stirring 3 times during the fermentation to ensure a solid-liquid ratio of 0.7:1 and a selenium content of 0.02-0.04mg / kg;

[0062] S4. Matured selenium-enriched straw: Surface soil was collected from the arsenic-contaminated area of ​​Nanning, Guangxi. The soil was air-dried, crushed, and passed through a 20-mesh sieve. 75 g of pretreated raw material (selenium-enriched straw after fermentation with a bacterial agent) was added to each kilogram of soil. Sigma-Aldrich S0882 (>95%) sodium selenate was added as a selenium supplement to replenish the selenium content to 100 μg / kg. The soil was matured for 30 days to allow for sufficient interaction between microorganisms, organic matter, selenium, and other nutrients in the soil, achieving a state of chemical stability and optimized biological activity, thereby creating suitable conditions for subsequent phytoremediation.

[0063] S5. Transplanting tall centipede grass: Transplant centipede grass 15-20 cm high;

[0064] S6. Setting up replicate groups: setting up three replicate groups for the above steps, and then planting the tall centipede grass for 45 days;

[0065] S7. Determination of selenium and arsenic contents in soil and Scolopendra suber: After the samples were digested with HNO3-H2O2 (USEPA Method 3050B), ICP-MS determined the effective selenium content in the soil to be 34.00-86.20 mg / kg, the selenium content in the Scolopendra suber leaves to be 30.95-45.38 mg / kg, the arsenic content in the leaves to be 7.06-14.67 mg / kg, and the Scolopendra suber biomass to be 11.17-15.40 g.

[0066] Table 3: Straw selenium content, soil available selenium content, leaf selenium and arsenic content, and biomass of the straw fermentation liquid treatment group in Example 3

[0067]

[0068] Comparative Example 1:

[0069] The difference between this comparative example and Example 1 is that the comparative example comprises the following steps:

[0070] S1. Collection of arsenic-contaminated soil: Surface soil was collected from the arsenic-contaminated area in Nanning, Guangxi, and air-dried, crushed, and passed through a 20-mesh sieve to obtain arsenic-contaminated soil;

[0071] S2. Take three 1 kg portions of arsenic-contaminated soil and place them in separate planting containers (flower pots). Add 80 μg, 100 μg, and 140 μg of the selenium supplement Sigma-Aldrich S0882 (>95%) sodium selenate to each of the three portions of arsenic-contaminated soil, respectively, and water thoroughly.

[0072] S3. Transplanting tall centipede grass: Transplant centipede grass 15-20 cm high;

[0073] S4. Setting up replicate groups: setting up 3 replicate groups for the above steps, and then planting the tall centipede grass for 45 days;

[0074] S5. Determination of selenium and arsenic contents in soil and centipede grass: After the samples were treated with the HNO3-H2O2 (USEPA Method 3050B) digestion method, ICP-MS determination showed that the effective selenium content in the soil with 100 μg of selenium supplement added was 25.20 mg / kg, the selenium content in the leaves was 30.85 mg / kg, the arsenic content in the leaves was 6.75 mg / kg, and the centipede grass biomass was 6.70 g.

[0075] Table 4: Comparative Example 1: Soil available selenium content, leaf selenium and arsenic content, and biomass of the control group without straw application

[0076]

[0077] Comparative Example 2:

[0078] The difference between this comparative example and Example 1 is that the steps include:

[0079] S1. Collecting ordinary rice straw: Collect ordinary rice straw in Nanling County, Wuhu, and place it in a cool and dry place to air dry. The selenium content of the straw is measured to be ≤ 0.05 mg / kg, which is considered to be normal selenium content.

[0080] S2. Preparing pretreated raw materials: using a cutting machine to cut the straw raw materials into 2-5 cm long pieces, passing them through a 10-mesh sieve, and taking the sieved pulverized straw to obtain pretreated raw materials;

[0081] S3. Matured selenium-enriched straw: Surface soil was collected from an arsenic-contaminated area in Nanning, Guangxi. The soil was air-dried, crushed, and passed through a 20-mesh sieve. 18 g of pretreated raw material (crushed ordinary straw) was added per kilogram of soil and the soil was matured for 30 days.

[0082] S4. Transplanting tall centipede grass: Transplant centipede grass 15-20 cm high;

[0083] S5. Setting up replicate groups: setting up three replicate groups for the above steps, and then planting the tall centipede grass for 45 days;

[0084] S6. Determination of selenium and arsenic contents in soil and centipede grass: After the samples were treated with HNO3-H2O2 (USEPA Method 3050B) digestion method, ICP-MS was used to determine the effective selenium content in the soil to be 0.5700 mg / kg, the selenium content in centipede grass leaves to be 0.1116 mg / kg, the arsenic content in the leaves to be 3.550 mg / kg, and the centipede grass biomass to be 5.310 g.

[0085] Table 5: Comparative Example 2: Soil available selenium content, leaf selenium and arsenic content, and biomass of the control group with ordinary straw

[0086]

[0087] From the above data, it can be seen that the selenium-containing phytoremediation enhancer of the present invention has shown certain effectiveness in enhancing phytoremediation of arsenic-contaminated soil:

[0088] From the perspective of arsenic absorption by centipede grass, it can be seen from the comparison of Examples 2 and 3 with Example 1 and Comparative Examples 1 and 2 that the selenium-containing phytoremediation enhancer of the present invention significantly improves the arsenic absorption efficiency of centipede grass through multi-stage technology integration.

[0089] In Example 1, after selenium-enriched rice straw was used and matured, the arsenic content in the leaves of centipede grass was slightly increased compared with the unremediated soil (6.90-14.08 mg / kg in Example 1, 6.75-4.10 mg / kg in Comparative Example 1, and 3.55 mg / kg in Comparative Example 2), indicating that although simple fermentation can activate some selenium forms, the enhancement effect is limited.

[0090] In Example 2, on this basis, the straw raw material is fermented with soil for a period of time to produce a selenium-containing plant remediation enhancer. The microorganisms in the soil degrade cellulose and lignin, releasing more bound selenium and promoting its conversion to inorganic form, thereby further increasing the arsenic content in the leaves to 13.65-14.67 mg / kg, which is a significant increase compared to the method of Example 1.

[0091] Example 3 is further supplemented with a bacterial agent on the basis of Example 2, and the added Bacillus subtilis and Candida utilis are used to cooperate with the microorganisms in the soil to degrade cellulose and lignin, release more bound selenium and promote its conversion to an inorganic form, and finally achieve a leaf arsenic content of up to 45.380 mg / kg, which is several times higher than that of the control group (Comparative Example 1 is 6.75-4.10 mg / kg, and Comparative Example 2 is 3.55 mg / kg). At the same time, the biomass increases by nearly 3 times (the biomass of the centipede grass of Example 3 is 15.40 g / strain, the biomass of the centipede grass of Comparative Example 1 is 4.31-6.70 g / strain, and the biomass of the centipede grass of Comparative Example 2 is 5.31 g / strain). In contrast, the repair effects of Comparative Example 1 and Comparative Example 2 (ordinary straw) without the addition of a repair agent are significantly lower than those of the present invention.

[0092] From the perspective of the absorption of arsenic by centipede grass, the arsenic content in the centipede grass leaves increased in some examples, indicating that the enhancer promoted the enrichment of arsenic in the soil by centipede grass, and helped to reduce the arsenic content in the soil.

[0093] From the perspective of soil available selenium content, the present invention significantly increases the soil available selenium content through the synergistic effect of selenium-enriched rice straw and microorganisms. In Example 1, selenium-enriched rice straw is crushed and mixed with soil in proportion for maturation. The soil available selenium content is increased to 25.40-44.87 mg / kg, which is higher than that of unrepaired soil (only 0.57 mg / kg in Comparative Example 2). This is mainly due to the conversion of organic selenium into inorganic selenium forms by microorganisms. Although the soil available selenium in Comparative Example 1 is as high as 91.51 mg / kg, it is obviously caused by the addition of excessive selenium, and the economic benefit is low.

[0094] Example 2 On this basis, a fermentation process was added to make a strengthener. By adjusting parameters such as the solid-liquid ratio and stirring frequency, the effective selenium content in the soil was expanded to 39.67-76.27 mg / kg without adding exogenous bacterial agents, indicating that microbial metabolic activity further degraded straw cellulose and lignin, releasing more potential selenium resources.

[0095] In Example 3, a composite bacterial agent of Bacillus subtilis and Candida utilis was added to the selenium-rich straw and soil mixture for fermentation (mass ratio 1:1). The microorganisms directional converted the selenium form and accelerated the fermentation process. The effective selenium content was comparable to that of Example 2 (34.00-86.20 mg / kg), but the arsenic content of the centipede grass leaves was significantly increased to a maximum of 45.38 mg / kg (several times higher than the maximum of 6.75 mg / kg in Comparative Example 1). In contrast, Comparative Example 2 (ordinary straw) had a weak repair effect due to the lack of selenium strengthening, with an effective selenium content of only 0.57 mg / kg and an arsenic content of only 3.55 mg / kg in the centipede grass leaves.

[0096] When the selenium supplementation exceeded the threshold, arsenic accumulation in centipede grass leaves decreased, biomass decreased, and symptoms of selenium toxicity, such as brown spots on the leaves, were observed. Different treatment methods, such as crushing, conventional composting, and composting with microbial agents in Examples 1 to 3, showed varying effects on the restoration and soil fertility improvement. However, all were superior to Comparative Example 1, which did not add straw treatment products, and Comparative Example 2, which added conventional straw. This demonstrates the feasibility, effectiveness, and superiority of using selenium-enriched rice straw as a restoration enhancer.

[0097] The present invention converts the organic selenium that is easy to degrade and absorb and transform in selenium-rich straw into an inorganic selenium form that is easily absorbed by plants by microbial metabolism and aerobic fermentation, significantly improving the effective selenium content in soil (reaching 86.20mg / kg in Example three, several times higher than that of unrepaired soil), while combining the supplement of exogenous sodium selenate, forming a selenium-arsenic antagonism mechanism, prompting the enrichment of centipede grass to be greatly improved (leaf arsenic content reaches 7.06-14.67mg / kg in Example three, higher than that of ordinary straw control group). In addition, the organic matter and nitrogen, phosphorus and potassium components in the fermentation liquid effectively improve soil fertility and promote plant growth (biomass reaches 15.40g / strain in Example three, nearly 3 times higher than the 5.31g / strain of Comparative Example 2). Field test data show that the technology of the present invention not only realizes the efficient repair of arsenic-contaminated soil, but also synchronously improves soil sustainability, and after repair, the effective selenium content in soil (34.00-86.20mg / kg) is within the safety threshold, avoiding the risk of secondary pollution. The core advantage of this invention lies in the resource utilization of selenium-rich agricultural waste, the enhancement of plant metabolic functions and the eco-friendly synergistic repair mechanism. The organic selenium source of easily selenium-enriched straw is selected as a part to cooperate with microbial degradation to improve the selenium absorption capacity of centipede grass, providing an innovative solution for the treatment of arsenic-contaminated farmland that is both economical and engineering practical.

[0098] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A selenium-containing plant repair enhancer, characterized in that The enhancer is fermentation liquid made by fermenting selenium-enriched rice straw.

2. A selenium-containing phytoremediation enhancer according to claim 1, characterized in that: The selenium content of the selenium-enriched rice straw is 0.1-0.9 mg / kg.

3. A selenium-containing phytoremediation enhancer according to claim 1, characterized in that: The selenium content of the fermentation liquid is 0.02-0.05 mg / kg.

4. A method for preparing a selenium-containing plant repair enhancer, characterized in that: The following steps are involved: S1. Collect selenium-rich rice straw: collect selenium-rich rice straw with a selenium content of 0.1-0.9 mg / kg and place it in a cool and dry place to dry naturally; S2. Preparing pretreated raw materials: using a cutting machine to cut and crush the selenium-rich straw raw materials to obtain pretreated raw materials; S3. Fermentation: The pretreated raw materials are made into raw materials before fermentation, which are fully moistened with water and then fermented to obtain fermentation liquid.

5. The method for preparing a selenium-containing plant repair enhancer according to claim 4, wherein: In the step S3, the solid-liquid ratio after sufficient wetting with water is 0.7:1, the fermentation time is 45-60 days, and the mixture is stirred at least once during the fermentation period.

6. The method for preparing a selenium-containing phytoremediation enhancer according to claim 4, wherein: The step S3 includes: mixing the pretreated raw material with the soil to prepare the raw material before fermentation.

7. The method for preparing a selenium-containing phytoremediation enhancer according to claim 4, wherein: The step S3 includes: mixing the pretreated raw material with the bacterial agent, and then mixing the mixed product with soil to prepare the raw material before fermentation.

8. The method for preparing a selenium-containing phytoremediation enhancer according to claim 7, wherein: The bacterial agent is a mixture of Bacillus subtilis and Candida utilis, and the ratio of Bacillus subtilis to Candida utilis is 1:

1.

9. Use of a selenium-containing plant remediation enhancer according to any one of items 1 to 3 in improving the soil remediation ability of plants that accumulate heavy metals and enhancing soil fertility.

10. The use of a selenium-containing plant repair enhancer according to claim 9, characterized in that: The following steps are involved: S1. Collect surface soil from heavy metal contaminated areas; S2. Add enhancers to the soil to supplement selenium sources and achieve balanced maturation; S3. Plant plants that have adsorption effects on heavy metals in the balanced and mature soil to complete the absorption of heavy metals in the soil.

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