Heavy metal contaminated soil remediation method based on natural minerals and plants
By combining natural minerals and plants for remediation, iron and sulfur are used to fix heavy metals and promote plant enrichment, solving the problems of high cost and long cycle in the remediation of heavy metal pollution in soil, and achieving efficient and low-cost remediation of heavy metal polluted soil.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUNAN UNIV
- Filing Date
- 2026-01-28
- Publication Date
- 2026-04-21
AI Technical Summary
Existing soil heavy metal pollution remediation technologies suffer from high costs and long remediation cycles. Chemical remediation materials are expensive, while phytoremediation is inefficient and time-consuming.
A combined approach of natural minerals and plants is employed to provide ramie with nutrients from iron and sulfur in pyrite and marcasite. Heavy metals are fixed through oxidation and precipitation, and free radicals are used to promote plant enrichment. This approach combines chemical and phytoremediation techniques.
It achieves efficient and low-cost remediation of heavy metal contaminated soil, shortens the remediation cycle, maintains plant growth vitality, reduces the mobility of heavy metals and fixes them in the plant roots, and is simple to operate and environmentally friendly.
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Figure CN121892498A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of soil heavy metal pollution remediation, specifically to a method for remediating contaminated soil using a combination of natural minerals and plants. Background Technology
[0002] Heavy metal pollution in soil stems from the combined effects of natural processes and human activities. Given the inherent high biotoxicity and environmental mobility of heavy metals, they can accumulate in the human body through the biomagnification effect of the food chain, posing health risks to multiple organ systems. Soil is the cornerstone of maintaining ecosystem balance and human civilization; its environmental quality directly determines the safety and quality of agricultural products and public health and well-being. Therefore, it is imperative to address cadmium pollution in soil to ensure human safety and promote sustainable development.
[0003] Existing technologies for remediating heavy metal pollution in soil are mainly classified into physical remediation, chemical remediation, and bioremediation. Chemical remediation has advantages such as wide application, minimal damage to the soil environment, and simple operation; however, the cost of chemically synthesized materials is high. Phytoremediation, on the other hand, boasts advantages such as large biomass, strong accumulation capacity, high tolerance, and low cost, making it an ideal and promising remediation method. However, phytoremediation has a long cycle and low efficiency. Natural minerals are widely available and abundant, with extremely low raw material costs, offering a more economical option compared to synthetic chemical remediation agents.
[0004] Natural minerals, as cost-effective mineral materials, can mediate the generation of free radicals. Free radicals can stimulate plant physiological phenotypes, and the combination of these two factors leads to the accumulation of heavy metals from contaminated soil within the plant and their transfer to the above-ground parts of ramie, facilitating subsequent treatment. Therefore, this paper presents a soil remediation method based on natural minerals and plants that combines chemical remediation and phytoremediation for the efficient remediation of heavy metal pollution in soil, especially cadmium pollution. Summary of the Invention
[0005] To address the issues of high cost and long remediation cycles in existing soil heavy metal pollution remediation technologies, this invention provides a cost-effective soil remediation method based on natural minerals and plants that combines chemical remediation and phytoremediation for efficient remediation of soil heavy metal pollution, especially cadmium pollution.
[0006] This invention provides a soil remediation method based on natural minerals and plants. The natural minerals include pyrite and marcasite, the plants include ramie, and the heavy metals include cadmium. The natural minerals work synergistically with the plants to remediate soil contaminated with heavy metals. Specifically, the iron and sulfur elements in the natural minerals provide nutrients for plant growth. Secondly, the iron and sulfur elements in the natural minerals fix the heavy metals in the plant roots through oxidation and precipitation. Finally, the free radicals mediated by the natural minerals promote the accumulation of heavy metals in the plants. The combination of chemical remediation and phytoremediation enriches the heavy metals in the contaminated soil within the plants.
[0007] Includes the following steps:
[0008] S1. The natural mineral is crushed, passed through a 200-mesh sieve, ultrasonically treated with ethanol, washed with dilute sulfuric acid and ultrapure water, filtered, and vacuum dried at 60°C.
[0009] S2. Add the natural minerals treated in S1 to the soil and mix them evenly;
[0010] S3. Transplant the entire plant seedling into the mixed soil and continue for 40 days.
[0011] In S2, the amount of the natural mineral added is 0.1-2%.
[0012] In S3, ultrapure water was applied periodically to maintain soil moisture content at 60% of maximum field capacity. The cultivation temperature was 25 ℃, and the light ratio was 14 h / 10 h (day / night).
[0013] During the remediation process, changes in soil organic matter (SOM) content were measured using the potassium dichromate-concentrated sulfuric acid method to assess changes in the fertility of the target soil.
[0014] The chlorophyll level of the plants was determined by ethanol extraction, the malondialdehyde (MDA) level was determined by the thiobarbituric acid method (TBA method), and the peroxidase activity (POD) was determined by a peroxidase activity assay kit to assess the growth potential of ramie.
[0015] The level of free radicals in soil was determined by electron paramagnetic resonance.
[0016] The heavy metal pollution was cadmium-contaminated soil. Changes in the bioavailability of cadmium in the soil were monitored by diethylenetriaminepentaacetic acid (DTPA) extraction, and the modified European Community Reference Bureau (BCR) continuous extraction method was used to assess the speciation characteristics of cadmium after remediation.
[0017] The technical solution of this invention has the following advantages:
[0018] Compared to simple chemical or phytoremediation, the soil remediation method based on natural minerals and plants described in this invention utilizes the iron and sulfur elements in natural minerals to promote chlorophyll synthesis in ramie, providing sufficient material and energy for ramie to cope with heavy metal stress. This effectively maintains the growth vitality and physiological functions of ramie, thereby ensuring and enhancing its potential for continuous remediation of heavy metal-contaminated soil. The iron and sulfur elements in natural minerals strongly bind with cadmium through oxidation and other processes, passivating cadmium in the soil, reducing its mobility, and fixing it to plant roots. Free radicals mediated by natural minerals stimulate plant roots, increasing endocytosis and promoting cadmium absorption by ramie, thus increasing cadmium accumulation in ramie. Compared to other soil remediation methods, this method is simple to operate, low in cost, shortens the remediation cycle, has stable effects, is environmentally friendly, and causes minimal physical damage to the soil. This method has strong adaptability and practicality, and has significant application and promotion value. Attached Figure Description
[0019] Figure 1 Soil pH and organic matter (SOM) content for Examples 1, 2, 3, 4, Comparative Examples 1, 2, 3, 4, 5, and 6.
[0020] Figure 2 The changes in available cadmium (DTPA-Cd) content and heavy metal speciation in soils were compared with those in Comparative Examples 1, 2, 3, 4, and 5.
[0021] Figure 3 The changes in available cadmium (DTPA-Cd) content and heavy metal speciation in soils of Examples 1, 2, 3, 4, and Comparative Example 6 are shown.
[0022] Figure 4 The changes in soil superoxide anion free radical and hydroxyl free radical levels are shown in Examples 1, 2, 3, 4, and Comparative Example 6.
[0023] Figure 5 The ramie height, chlorophyll content, and physiological parameters (MDA, POD) content of Examples 1, 2, 3, 4, and Comparative Example 6 are used for comparison.
[0024] Figure 6 The enrichment of cadmium in ramie is shown in Examples 1, 2, 3, 4, and Comparative Example 6. Detailed Implementation
[0025] To further illustrate the objectives, technical solutions, and advantages of the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on these embodiments of the present invention, all other embodiments obtained without creative effort are within the protection scope of the present invention.
[0026] This invention discloses a soil remediation method based on natural minerals and plants. The natural minerals include pyrite and marcasite, the plants include ramie, and the heavy metals include cadmium. The natural minerals work synergistically with the plants to remediate soil contaminated with heavy metals. Specifically, the iron and sulfur elements in the natural minerals provide nutrients for plant growth. Secondly, the iron and sulfur elements in the natural minerals fix the heavy metals in the plant roots through oxidation and precipitation. Finally, the free radicals mediated by the natural minerals promote the accumulation of heavy metals in the plants. The combination of chemical remediation and phytoremediation enriches the heavy metals in the contaminated soil within the plants.
[0027] Specifically, the method includes the following steps:
[0028] S1. The natural mineral is crushed, passed through a 200-mesh sieve, ultrasonically treated with ethanol, washed with dilute sulfuric acid and ultrapure water, filtered, and vacuum dried at 60°C.
[0029] S2. Add the natural minerals treated in S1 to the soil and mix them evenly; weigh 1 kg of the treated soil and add it to a flowerpot with a diameter of 12 cm and a height of 16 cm.
[0030] S3. Transplant the entire plant seedling into the soil treated by S2, one plant per pot, and continue planting for 40 days.
[0031] In S2, the amount of the natural mineral added is 0.1%-2%.
[0032] In S3, ultrapure water was applied periodically to maintain soil moisture content at 60% of maximum field capacity. The planting temperature was 25 ℃, and the light ratio was 14 h / 10 h (day / night).
[0033] During the remediation process, changes in soil organic matter (SOM) content were measured using the potassium dichromate-concentrated sulfuric acid method to assess changes in the fertility of the target soil.
[0034] The chlorophyll level of the plants was determined by ethanol extraction, the malondialdehyde (MDA) level was determined by the thiobarbituric acid method (TBA method), and the peroxidase activity (POD) was determined by a peroxidase activity assay kit to assess the growth potential of ramie.
[0035] The level of free radicals in soil was determined by electron paramagnetic resonance.
[0036] The heavy metal pollution was cadmium-contaminated soil. Changes in the bioavailability of cadmium in the soil were monitored by diethylenetriaminepentaacetic acid (DTPA) extraction, and the modified European Community Reference Bureau (BCR) continuous extraction method was used to assess the speciation characteristics of cadmium after remediation.
[0037] The method and its effects described in this application will be explained in detail below using specific embodiments and comparative examples.
[0038] Comparative Example 1:
[0039] This comparative example is the basic comparative example, meaning that no natural minerals are added and no plants are grown. It is numbered CK.
[0040] Specifically, farmland soil samples were collected from XX city in XX province, China. Referring to the Chinese Standard for Risk Management of Agricultural Land Soil (GB15618-2018), the farmland soil was stabilized by cadmium chloride treatment, resulting in a serious exceedance of the cadmium content in the farmland soil, with a total cadmium content of 2.99 mg / kg (the risk screening value is 0.3 mg / kg).
[0041] The steps for this comparative example are as follows:
[0042] Pretreatment: The cadmium-contaminated soil used for testing was air-dried, ground up, and animal and plant residues were removed.
[0043] Remediation treatment: No natural minerals were added to the pretreated cadmium-contaminated soil; only ultrapure water was added. During the remediation process, the soil moisture content was maintained at 60% of the maximum field capacity, the incubation temperature was 25 ℃, and the light ratio was 14 h / 10 h (day / night). Soil samples were taken on day 40.
[0044] Comparative Example 2:
[0045] In this comparative example, pyrite was added alone to remediate cadmium-contaminated soil for testing, designated as 0.88%P.
[0046] Specifically, farmland soil samples were collected from XX city in XX province, China. Referring to the Chinese Standard for Risk Management of Agricultural Land Soil (GB15618-2018), the farmland soil was stabilized by cadmium chloride treatment, resulting in a serious exceedance of the cadmium content in the farmland soil, with a total cadmium content of 2.99 mg / kg (the risk screening value is 0.3 mg / kg).
[0047] The steps for this comparative example are as follows:
[0048] Pretreatment: The cadmium-contaminated soil used for testing was air-dried, ground up, and animal and plant residues were removed.
[0049] Mixing treatment: Pyrite is mixed and stirred evenly with the pretreated cadmium-contaminated soil. The dosage of pyrite added is 0.88% of the soil mass.
[0050] Remediation treatment: Ultrapure water was added to the pyrite-added soil periodically. During the remediation process, the soil moisture content was maintained at 60% of the maximum field capacity. The incubation temperature was 25 ℃, and the light ratio was 14 h / 10 h (day / night). Soil samples were taken on day 40.
[0051] Comparative Example 3:
[0052] In this comparative example, pyrite was added alone to remediate cadmium-contaminated soil for testing. The amount of pyrite added was 1.76%, designated as 1.76%P. The remaining steps were the same as in Comparative Example 2.
[0053] Comparative Example 4:
[0054] In this comparative example, pyrite was added alone to remediate cadmium-contaminated soil for testing, designated as 0.88%C.
[0055] Specifically, farmland soil samples were collected from XX city in XX province, China. Referring to the Chinese Standard for Risk Management of Agricultural Land Soil (GB15618-2018), the farmland soil was stabilized by cadmium chloride treatment, resulting in a serious exceedance of the cadmium content in the farmland soil, with a total cadmium content of 2.99 mg / kg (the risk screening value is 0.3 mg / kg).
[0056] The steps for this comparative example are as follows:
[0057] Pretreatment: The cadmium-contaminated soil used for testing was air-dried, ground up, and animal and plant residues were removed.
[0058] Mixing treatment: Mix the pyrite with the pretreated cadmium-contaminated soil and stir evenly. The dosage of pyrite added is 0.88% of the soil mass.
[0059] Remediation treatment: Ultrapure water was added to the soil containing pyrite periodically. During the remediation process, the soil moisture content was maintained at 60% of the maximum field capacity. The incubation temperature was 25 ℃, and the light ratio was 14 h / 10 h (day / night). Soil samples were taken on day 40.
[0060] Comparative Example 5:
[0061] In this comparative example, pyrite was added alone to remediate cadmium-contaminated soil for testing. The amount of pyrite added was 1.76%, designated as 1.76%C. The remaining steps were the same as in Comparative Example 4.
[0062] Comparative Example 6:
[0063] In this comparative example, ramie was planted alone to remediate cadmium-contaminated soil for testing, and this example was designated CK-B.
[0064] Specifically, farmland soil samples were collected from XX city in XX province, China. Referring to the Chinese Standard for Risk Management of Agricultural Land Soil (GB15618-2018), the farmland soil was stabilized by cadmium chloride treatment, resulting in a serious exceedance of the cadmium content in the farmland soil, with a total cadmium content of 2.99 mg / kg (the risk screening value is 0.3 mg / kg).
[0065] The steps for this comparative example are as follows:
[0066] Pretreatment: The cadmium-contaminated soil used for co-remediation was air-dried, ground, and animal and plant residues were removed. 1 kg of the treated soil was weighed and added to a flowerpot with a diameter of 12 cm and a height of 16 cm.
[0067] Remediation Treatment: No natural minerals were added to the cadmium-contaminated soil for co-remediation; only ramie seedlings were planted, with one seedling transplanted into each pot. Ultrapure water was periodically added to the pyrite-contaminated soil. During the remediation process, the soil moisture content was maintained at 60% of maximum field capacity, the cultivation temperature was 25 ℃, and the light ratio was 14 h / 10 h (day / night). Soil samples were taken on day 40.
[0068] Example 1:
[0069] In this embodiment, pyrite and ramie were used to remediate cadmium-contaminated soil. A 0.88% dose of pyrite and ramie was selected for soil remediation, designated as 0.88%PB.
[0070] Specifically, farmland soil samples were collected from XX city in XX province, China. Referring to the Chinese Standard for Risk Management of Agricultural Land Soil (GB15618-2018), the farmland soil was stabilized by cadmium chloride treatment, resulting in a serious exceedance of the cadmium content in the farmland soil, with a total cadmium content of 2.99 mg / kg (the risk screening value is 0.3 mg / kg).
[0071] The steps for remediating cadmium-contaminated soil using pyrite and ramie in this embodiment are as follows:
[0072] Pretreatment: The cadmium-contaminated soil is air-dried, ground up, and animal and plant residues are removed.
[0073] Mixing treatment: Mix pyrite with cadmium-contaminated soil evenly. The dosage of pyrite added is 0.88% of the soil mass. Weigh 1 kg of the treated soil and add it to a flowerpot with a diameter of 12 cm and a height of 16 cm.
[0074] Remediation treatment: Ramie seedlings were transplanted into cadmium-contaminated soil supplemented with pyrite, one seedling per pot. Ultrapure water was added to the pyrite-supplemented soil periodically. During the remediation process, the soil moisture content was maintained at 60% of the maximum field capacity, the cultivation temperature was 25 ℃, and the light ratio was 14 h / 10 h (day / night). Soil samples were taken on day 40.
[0075] Example 2:
[0076] In this embodiment, pyrite and ramie were used to remediate cadmium-contaminated soil. A 1.76% dose of pyrite and ramie was selected for soil remediation, designated as 1.76%PB. The remaining steps were the same as in Example 1.
[0077] Example 3:
[0078] In this embodiment, galena synergistic with ramie was used to remediate cadmium-contaminated soil. A 0.88% dose of galena synergistic with ramie was selected for soil remediation, designated as 0.88%CB.
[0079] Specifically, farmland soil samples were collected from XX city in XX province, China. Referring to the Chinese Standard for Risk Management of Agricultural Land Soil (GB15618-2018), the farmland soil was stabilized by cadmium chloride treatment, resulting in a serious exceedance of the cadmium content in the farmland soil, with a total cadmium content of 2.99 mg / kg (the risk screening value is 0.3 mg / kg).
[0080] The steps for remediating cadmium-contaminated soil using natural minerals and ramie in this embodiment are as follows:
[0081] Pretreatment: The cadmium-contaminated soil is air-dried, ground up, and animal and plant residues are removed.
[0082] Mixing treatment: Mix pyrite with cadmium-contaminated soil evenly. The dosage of pyrite added is 0.88% of the soil mass. Weigh 1 kg of the treated soil and add it to a flowerpot with a diameter of 12 cm and a height of 16 cm.
[0083] Remediation treatment: Ramie seedlings were transplanted into cadmium-contaminated soil supplemented with pyrite, one seedling per pot. Ultrapure water was added to the soil regularly. During the remediation process, the soil moisture content was maintained at 60% of the maximum field capacity. The cultivation temperature was 25 ℃, and the light ratio was 14 h / 10 h (day / night). Soil samples were taken on day 40.
[0084] Example 4:
[0085] In this embodiment, galena synergistic with ramie was used to remediate cadmium-contaminated soil. A 1.76% dose of galena synergistic with ramie was selected for soil remediation, designated as 1.76%CB. The remaining steps were the same as in Example 3.
[0086] Results Detection and Analysis
[0087] I. Analysis of Soil Physicochemical Properties
[0088] The soil physicochemical properties of Examples 1, 2, 3, 4, Comparative Examples 1, 2, 3, 4, 5, and 6 are shown in the table below.
[0089] Table 1. Soil physicochemical properties and cadmium available concentration in each example and comparative example.
[0090] pH SOM (g / kg) DTPA-Cd (mg / kg) Comparative Example 1 5.59 52.35 2.88 Comparative Example 2 5.11 56.31 2.32 Comparative Example 3 4.54 57.52 1.87 Comparative Example 4 5.01 56.89 2.35 Comparative Example 5 4.47 58.01 1.88 Comparative Example 6 5.67 53.66 2.67 Example 1 5.43 58.11 1.68 Example 2 5.26 60.45 1.49 Example 3 5.38 59.07 1.73 Example 4 5.16 61.21 1.55
[0091] As shown in Table 1, soil pH was significantly lower in Comparative Examples 2-5 compared to Comparative Example 1; soil pH was slightly higher in Comparative Example 6 compared to Comparative Example 1; and soil pH was significantly lower in Examples 1-4 compared to Comparative Example 6, but the decrease in soil pH in Examples 1-4 was smaller than that in Comparative Examples 2-5. Figure 1 Compared with Comparative Example 1, Comparative Examples 2-5 showed an increase in soil SOM content; Comparative Example 6 showed a slight increase in soil SOM content compared with Comparative Example 1; and Examples 1-4 showed a greater increase in soil SOM content compared with Comparative Examples 2-5. Figure 1 Compared with Comparative Example 1, the concentration of available cadmium in soil decreased in Comparative Examples 2-5. Figure 2 Compared to Comparative Example 1, Comparative Example 6 showed a decrease in the concentration of available cadmium in the soil; compared to Comparative Example 6, Examples 1-4 showed a decrease in the concentration of available cadmium in the soil, but the decrease was greater than that in Comparative Examples 2-5. Figure 3 ).
[0092] The above indicates that both natural minerals and ramie can increase soil SOM content, and their synergistic remediation significantly increases soil SOM content, thereby significantly improving soil fertility. Natural minerals significantly lower soil pH, while ramie can slow down the downward trend in soil pH. The decrease in soil pH did not lead to an increase in available cadmium content in the soil. This is because iron and sulfur strongly bind with heavy metals, passivating cadmium and thus reducing the concentration of available cadmium in the soil. This suggests that natural minerals can reduce cadmium mobility, fixing it at plant roots. Simultaneously, the combined action of ramie and natural minerals maintains the soil's physicochemical properties in a favorable state, minimizing the impact on the microbial environment.
[0093] II. Analysis of the Results of Heavy Metal Speciation in Soil
[0094] like Figure 2 As shown, compared to Comparative Example 1, the proportion of acid-soluble cadmium in soil increased by 18%-23% in Comparative Examples 2-3, and by 25% in Comparative Examples 4-5; Figure 3As shown, compared to Comparative Example 6, the proportion of acid-soluble cadmium in soil increased by 14% - 18% in Examples 1-2, and by 16% - 22% in Examples 3-4.
[0095] The above explains that the addition of natural minerals to the soil affects the form of heavy metals by influencing SOM and pH levels, leading to an increase in the proportion of acid-soluble cadmium in the soil.
[0096] III. Soil Free Radical Level Analysis
[0097] Soil free radical levels in Examples 1, 2, 3, 4, and Comparative Example 6 are as follows: Figure 4 As shown.
[0098] In Comparative Example 6, the soil contained virtually no superoxide anion radicals. In Examples 1-2, superoxide anion radical peaks were present, with the superoxide anion radical level in Example 2 being higher than that in Example 1. In Examples 3-4, superoxide anion radical peaks were present, with the superoxide anion radical level in Example 4 being higher than that in Example 3. Similarly, in Comparative Example 6, the soil contained virtually no hydroxyl radicals. In Examples 1-2, hydroxyl radical peaks were present, with the hydroxyl radical level in Example 2 being higher than that in Example 1. In Examples 3-4, hydroxyl radical peaks were present, with the hydroxyl radical level in Example 4 being higher than that in Example 3.
[0099] The above explains that the reaction between iron and sulfur elements in natural minerals and air in the soil mediates the generation of free radicals in the soil.
[0100] IV. Cadmium Accumulation Content and Phenotypic Analysis in Ramie
[0101] The cadmium enrichment content and phenotype of ramie in Examples 1, 2, 3, 4, and Comparative Example 6 are shown in the table below.
[0102] Table 2. Cadmium enrichment content and phenotype of ramie in each example and comparative example.
[0103] Example 1 Example 2 Example 3 Example 4 Comparative Example 6 Cadmium enrichment level (μg / kg) 25.51 31.64 26.12 32.12 18.79 Height (cm) 24.7 23.5 23.9 22.1 26.4 Chlorophyll (mg / g) 1.95 2.43 2.01 2.36 1.83 MDA (μmol / g FW) 78.14 90.77 80.11 92.13 51.28 POD (U / g) 2028 2252 2075 2302 1132
[0104] As shown in Table 2, compared with Comparative Example 6, the height of ramie in Examples 1-2 decreased by 10.98%-16.28%, chlorophyll level increased by 28.96%-32.79%, MDA level increased by 77.01%-79.66%, and POD enzyme activity increased by 98.94%-103.35%. Figure 5 The cadmium enrichment level increased by 68.38-70.94%. Figure 6 ).
[0105] The above results indicate that although the height of ramie decreased in the examples, the iron and sulfur elements in the natural minerals, as essential plant nutrients, effectively increased the chlorophyll level of ramie and significantly enhanced photosynthetic efficiency. This provided sufficient material and energy for ramie to cope with cadmium stress, effectively maintaining its growth vitality and physiological functions, thereby ensuring and enhancing its potential for continuous remediation of cadmium-contaminated soil. Simultaneously, the MDA level and POD enzyme activity in ramie increased synchronously, indirectly indicating that the natural minerals mediated the generation of soil free radicals, stimulating endocytosis in ramie roots, leading to increased cadmium accumulation in ramie and consequently toxicity. The antioxidant system of ramie maintained cellular balance, such as... Figure 5 , Figure 6 As shown.
[0106] In summary, the results indicate that natural minerals can effectively increase the SOM content in the soil, thereby enhancing soil fertility. Furthermore, the iron and sulfur in natural minerals provide abundant substrates for ramie, promoting chlorophyll synthesis and ensuring photosynthesis. Secondly, the iron and sulfur in natural minerals react with oxygen in the soil and then strongly bind with cadmium, passivating the cadmium in the soil and reducing its availability. This weakens cadmium mobility and fixes it in the ramie roots. Natural minerals then mediate the generation of free radicals in the soil, stimulating endocytosis in the ramie roots and promoting the absorption of heavy metals, while also shortening the remediation cycle. Compared to other soil remediation methods, this method is simple to operate, low in cost, shortens the remediation cycle, has stable effects, is environmentally friendly, and causes minimal physical damage to the soil. This method is highly adaptable and practical, possessing significant application and promotion value.
[0107] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A soil remediation method based on natural minerals and synergistic plants, characterized in that, Natural minerals contain iron and sulfur, while plants are heavy metal accumulators. By combining the natural minerals with plant accumulation, soil contaminated with heavy metals can be remediated.
2. The soil remediation method based on natural minerals and synergistic plants according to claim 1, characterized in that, The natural minerals are pyrite and marcasite, the plant is ramie, and the heavy metal is cadmium.
3. The soil remediation method based on natural minerals and synergistic plants according to claim 1, characterized in that, Includes the following steps: S1. The natural mineral is crushed, passed through a 200-mesh sieve, ultrasonically treated with ethanol, washed with dilute sulfuric acid and ultrapure water, filtered, and vacuum dried at 60°C. S2. Add the natural minerals treated in S1 to the soil and mix them evenly; S3. Transplant the entire plant seedling into the mixed soil for planting.
4. The soil remediation method based on natural minerals and synergistic plants according to claim 3, characterized in that, In S2, the amount of the natural mineral added is 0.1-2%.
5. The soil remediation method based on natural minerals and synergistic plants according to claim 2, characterized in that, In S3, ultrapure water was applied periodically to maintain soil moisture content at 60% of maximum field capacity. The planting temperature was 25°C, and the light ratio was 14 h / 10 h (day / night).
6. The soil remediation method based on natural minerals and synergistic plants according to claim 1, characterized in that, During the remediation process, changes in soil organic matter (SOM) content were measured using the potassium dichromate-concentrated sulfuric acid method to assess changes in the fertility of the target soil.
7. The soil remediation method based on natural minerals and synergistic plants according to claim 1, characterized in that, The chlorophyll level of the plants was determined by ethanol extraction, the malondialdehyde (MDA) level was determined by the thiobarbituric acid method (TBA method), and the peroxidase activity (POD) was determined by a peroxidase activity assay kit to assess the growth potential of ramie.
8. The soil remediation method based on natural minerals and synergistic plants according to claim 1, characterized in that, During the remediation process, the free radicals in the soil were semi-quantitatively measured using electron paramagnetic resonance (EPR).
9. The soil remediation method based on natural minerals and synergistic plants according to claim 1, characterized in that, During the remediation process, changes in soil cadmium bioavailability were monitored using diethylenetriaminepentaacetic acid (DTPA) extraction, and a modified European Community Reference Bureau (BCR) continuous extraction method was used to assess the speciation characteristics of cadmium after remediation.