Application of vetch in repairing radium-contaminated soil

Abstract

The application provides application of a wild pea in repairing radium-polluted soil, and the wild pea is planted in radium-polluted soil for cultivation and management, when the wild pea grows to a mature stage, the aboveground part of the wild pea is removed from the polluted soil, or the wild pea is completely removed from the polluted soil; the above process is repeated until the radium content in the soil reaches an environmental safety standard. The wild pea is used to repair acidic radium-polluted soil in a subtropical monsoon climate zone, the wild pea grows normally in the acidic soil with low-level radioactive pollution and has no toxic and harmful phenomena. The wild pea at the mature stage has a high transfer coefficient and enrichment coefficient, the total radium removal amount of the aboveground part of the wild pea accounts for more than 80% of the total radium removal amount, and radium can be extracted from the low-level radium-polluted soil. The plant repair method provided by the application has simple operation process and convenient management, does not damage the basic structure and properties of the soil, and is suitable for repairing large-area acidic radium-polluted soil with low level.

Description

Technical Field

[0001] This invention relates to the field of environmental pollution control technology, and in particular to the application of wild pea in the remediation of radioactive radium contaminated soil. Background Technology

[0002] Anthropogenic sources of radium (Ra) primarily include the mining and smelting of uranium, other metals and non-metals, phosphate production and fertilizer use, phosphogypsum use, coal combustion, oil and gas production, wastewater treatment, and various wastes generated from these activities. Ra is a product of the natural decay chain of U and Th, and its natural radioactive isotopes include... 223 Ra (half-life approximately 11.4 days) 224 Ra (half-life approximately 3.66 days) 226 Ra

[0003] (Half-life approximately 1600 years) and 228 There are four types of uranium: Ra (with a half-life of approximately 5.75 years). The development of nuclear energy and other atomic energy industries has promoted uranium exploration and mining activities.

[0004] However, years of mining and smelting activities have generated waste materials such as slag and by-products containing natural radioactive nuclides such as uranium, thorium, and radium, as well as tunnel wastewater. These wastes come from decommissioned uranium mines and other sites. 226 Ra and other pollutants lead to increased environmental gamma radiation levels, radon release, and wind erosion spreading of dust containing long-lived alpha radioactive materials, contaminating surface or groundwater. Radium is highly mobile in the environment and can easily enter organisms through ingestion or inhalation, potentially causing serious radioactive hazards and threatening human health.

[0005] 226 Ra is most closely related to radiation protection and environmental protection. According to my country's "Regulations on Radiation Protection and Environmental Protection in Uranium Mining and Metallurgy" (GB 23727-2020), "After land decontamination and remediation, any 100m..." 2 Soil layers within the range 226 "The average activity concentration of Ra, after deducting the local background value, does not exceed 0.18 Bq / g, and it can be opened or used without restriction." Some radioactive radium-containing soils require remediation.

[0006] Compared to traditional physicochemical techniques, phytoremediation offers advantages in large-scale contaminated soil remediation, including lower costs and environmental friendliness. The phytoextraction strategy, which extracts metallic pollutants into plants and then harvests them, represents a relatively thorough phytoremediation method; however, research on its application in radium-contaminated soil remediation is currently limited.

[0007] Therefore, it is necessary to develop a method for remediating radioactive Ra-contaminated soil using plants. Summary of the Invention

[0008] To address the aforementioned problems in existing technologies, this invention applies wild peas to the remediation of radioactive radium-contaminated soil, demonstrating high efficacy. 226 Ra transfer coefficient and enrichment coefficient were measured. Good remediation results were achieved. Specifically, the aboveground parts of *Vicia sativa* contributed over 80% to the removal of Ra.

[0009] The specific details of the invention are as follows:

[0010] This invention provides an application of wild pea in the remediation of radioactive radium contaminated soil, the application being targeted at... 226 The activity concentration of Ra is 200-5000 Bg / kg. 226 Ra-contaminated soil, the applications include:

[0011] exist 226 Wild pea seeds are sown in Ra contaminated soil and cultivated. When the wild peas grow to maturity, the above-ground parts of the wild peas are removed from the contaminated soil, or all the wild peas are removed from the contaminated soil.

[0012] Repeat the above process until the... 226 Ra contaminated soil 226 Ra content meets environmental safety standards;

[0013] The above-ground parts of the wild pea are... 226 The enrichment factor of Ra is 0.69-0.75;

[0014] The roots of the wild pea 226 The enrichment factor of Ra is 0.94-1.04.

[0015] Optionally, the aboveground parts of the wild pea are... 226 The enrichment activity concentration of Ra was 351-365 Bq / kg, and the roots of the wild pea were used for... 226 The enrichment activity concentration of Ra is 480-518 Bq / kg.

[0016] Optionally, the 226 Ra-contaminated soil is a weakly acidic contaminated soil from a subtropical monsoon climate zone.

[0017] The 226 The pH value of Ra-contaminated soil is 5-6.

[0018] Optionally, the sowing rate of the wild pea seeds is 3-5 kg / mu.

[0019] Optionally, the wild pea seeds can be any commercially available variety.

[0020] Optionally, the cultivation management includes: for the 226The Ra-contaminated soil was leveled, finely ground, watered, and fertilized.

[0021] Optionally, the fertilization construction refers to the application of fertilizers during the fertilization process. 226 Base fertilizer was applied before planting the wild peas in Ra-contaminated soil, and top fertilizer was applied during the growth of the wild peas.

[0022] Optionally, both the base fertilizer and the top dressing are nitrogen, phosphorus, and potassium compound fertilizers.

[0023] Optionally, the watering operation is based on the... 226 The water shortage situation of Ra-contaminated soil was investigated, so that the... 226 The soil moisture content of Ra-contaminated soil remains at 40%-70% of field capacity.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] This invention provides an application of wild pea in the remediation of radioactive radium contaminated soil, by planting wild pea in... 226 Ra contaminated soil was planted and cultivated. Once the peas reached maturity, the above-ground parts were removed from the contaminated soil, or all the peas were removed entirely. This planting-cultivation-removal process was repeated until the soil was free of contaminated ra. 226 Ra content meets environmental safety standards. This invention uses wild pea to remediate acidic radioactive radium contaminated soil (200-5000 Bq / kg soil) in subtropical monsoon climate zones. Wild pea can grow normally in acidic soil with low to medium levels of radioactive contamination without exhibiting toxicity. At maturity, wild pea has a high transfer coefficient and enrichment coefficient, and the aboveground parts of wild pea... 226 Ra removal accounts for more than 80% of the total radium removal, and Ra can be extracted from soils with low Ra contamination. The phytoremediation method provided by this invention is simple to operate and easy to manage, and does not damage the basic structure and properties of the soil. It is suitable for the remediation of large areas of low-to-medium level acidic radium contaminated soil, providing a new method for the treatment of radioactive radium contaminated soil. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A flowchart illustrating the application of wild peas in the remediation of radioactive radium-contaminated soil, as provided in an embodiment of the present invention, is shown. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention. Furthermore, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of the present invention.

[0029] Specific experimental steps or conditions are not specified in the embodiments; they can be performed according to the conventional experimental steps or conditions described in the prior art. Reagents and other instruments used, unless otherwise specified, are all commercially available conventional reagent products. Furthermore, the accompanying drawings are merely illustrative diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore, repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0030] Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of this specification.

[0031] In the description of this invention, it should be understood that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0032] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] Preliminary field surveys around uranium mines revealed that only ferns, such as *Dictamnus dasycarpus*, are clearly Ra hyperaccumulators. However, the ecological effects of *Dictamnus dasycarpus* remain controversial due to limitations in propagation technology, the high labor input required for transplanting, and its strong allelopathic secretion. Therefore, it is necessary to find a plant with simple propagation techniques, convenient management, and that does not damage the basic soil structure for the remediation of radioactive radium-contaminated soil.

[0034] Based on this, the present invention has discovered through extensive experimental research that the legume *Vicia sativa* has high [potential for growth / development]. 226 Ra transfer coefficient and enrichment coefficient. The application of wild pea in the remediation of radioactive radium-contaminated soil achieved good remediation results. Therefore, this invention provides an application of wild pea in the remediation of radioactive radium-contaminated soil, the specific implementation details of which are as follows:

[0035] This invention provides an application of wild pea in the remediation of radioactive radium contaminated soil, the application being targeted at... 226 Ra activity ranges from 200 to 5000 Bg / kg. 226 Ra contaminated soil Figure 1 The following is a flowchart illustrating the application of wild pea in the remediation of radioactive radium contaminated soil according to an embodiment of the present invention. Figure 1 As shown, the application specifically includes the following steps:

[0036] Step 1, in 226 Wild pea seeds are sown in Ra contaminated soil and cultivated. When the wild peas grow to maturity, the above-ground parts of the wild peas are removed from the contaminated soil, or all the wild peas are removed from the contaminated soil.

[0037] Step 2: Repeat step 1 above until the soil contains... 226 The Ra content meets environmental safety standards.

[0038] This invention relates to the above-ground parts and roots of the wild pea plant and their effects on soil. 226 A study on the enrichment of Ra found that the aboveground parts of the wild pea plant... 226 The enrichment coefficient of Ra was 0.69–0.75; the roots of the wild pea were associated with… 226 The enrichment coefficients of Ra were 0.94–1.04; the aboveground parts of the wild pea plant were enriched by Ra. 226 The enrichment activity concentration of Ra was 351-365 Bq / kg, and the roots of the wild pea plant had an effect on... 226 The enrichment activity concentration of Ra was 480-518 Bq / kg. This indicates that wild peas can act as a remediation agent. 226 Plants used in Ra-contaminated soil have good remediation application value.

[0039] In some implementations, the use of peas for remediation of radioactive radium-contaminated soil is primarily targeted at weakly acidic contaminated soils in subtropical monsoon climate zones. 226 The pH value of Ra-contaminated soil is 5-6. The sowing rate of wild pea seeds is 3-5 kg / mu, and any commercially available wild pea seed variety can be used.

[0040] In some implementations, for seeding completed 226Cultivating and managing radium-contaminated soil can promote the growth of peas, increase their biomass, and thus improve the extraction rate of radioactive radium from the contaminated soil. Cultivation management includes leveling and refining the soil, watering, and fertilization. Specifically, during pea cultivation, watering should be done according to soil moisture levels to maintain a soil moisture content of 40%-70% of field capacity. Fertilization refers to applying base fertilizer before planting peas in radioactive radium-contaminated soil and applying top dressing during the pea's growth. Both base and top dressing are conventional N, P, K compound fertilizers. Local N, P, K compound fertilizers should be used, applied in appropriate amounts according to local soil conditions for both base and top dressing.

[0041] This invention provides an application of wild pea in the remediation of radioactive radium contaminated soil, by planting wild pea in... 226 Ra contaminated soil was planted and cultivated. Once the peas reached maturity, the above-ground parts were removed from the contaminated soil, or all the peas were removed entirely. This planting-cultivation-removal process was repeated until the soil was free of contaminated ra. 226 Ra content meets environmental safety standards. This invention uses wild pea to remediate acidic radioactive radium contaminated soil (200-5000 Bq / kg soil) in subtropical monsoon climate zones. Wild pea can grow normally in acidic soil with low to medium levels of radioactive contamination without exhibiting toxicity. At maturity, wild pea has a high transfer coefficient and enrichment coefficient, and the aboveground parts of wild pea... 226 Ra removal accounts for more than 70% of the total radium removal, and Ra can be extracted from soils with low Ra contamination. The phytoremediation method provided by this invention is simple to operate and easy to manage, and does not damage the basic structure and properties of the soil. It is suitable for the remediation of large areas of low-to-medium level acidic radium contaminated soil, providing a new method for the treatment of radioactive radium contaminated soil.

[0042] To enable those skilled in the art to better understand the present invention, the following embodiments will be used to describe in detail the application of a wild pea in the remediation of radioactive radium contaminated soil.

[0043] The following examples use low-to-medium level radioactive contaminated soil from decommissioned uranium mines in southern my country to plant wild peas on-site. The selected wild peas are commonly available commercial varieties. Other planting methods and varieties can also be used in the application process.

[0044] The fertilizers and pesticides used in the following examples can all be purchased through conventional commercial channels.

[0045] The field experiment was conducted in a decommissioned uranium mine in southern my country. The area has a subtropical monsoon climate. The physicochemical properties of the soil contaminated with radioactive radium are shown in Table 1. The soil at the demonstration site in the decommissioned uranium mine is sandy loam with an acidic pH.

[0046] Table 1 Physicochemical properties of the tested soils

[0047]

[0048] Example 1

[0049] (1) Field experiment on the absorption capacity of radium by wild peas

[0050] Loosen and level the soil at the contaminated site, and apply base fertilizer. Sow pea seeds (3 kg / acre) in the soil, cover with soil, and water appropriately. During the pea growth process, apply appropriate top dressing (such as commercially available NPK compound fertilizer), spray pesticides (such as commercially available abamectin and benzoyl peroxide), and water as needed, depending on crop growth and soil moisture, to promote pea growth. After 3 months of growth, harvest the entire plant, separating the above-ground parts and roots. Rinse with tap water and air dry naturally. After drying, pulverize and preserve the soil and plants for subsequent analysis.

[0051] (2) Repair capability verification

[0052] 1) The above-ground parts, roots, and soil of the wild pea 226 Ra activity concentration determination

[0053] In the soil 226 Ra was measured according to the "Rock Samples" standard. 226 Analysis method for Ra - Gas ejection method (GB / T13073-2010). In plants... 226 Ra was measured using a high-purity germanium gamma spectrometer in accordance with the standard GB / T 16145-2020, which specifies the method for gamma spectral analysis of radionuclides in biological samples.

[0054] Analysis results show that in the soil 226 When the Ra activity concentration is 488-512 Bq / kg, the aboveground parts of the wild pea plant have an effect on... 226 The enrichment activity concentration of Ra was 351-365 Bq / kg, and the roots of Vitex negundo had an effect on... 226 The enrichment activity concentration of Ra is 480-518 Bq / kg.

[0055] 2) The above-ground parts and roots of the wild pea have an effect on 226 Determination of Ra enrichment coefficient and transfer coefficient

[0056] Enrichment factor (BCF) = Ra specific activity of plant or plant tissue / specific activity of the nuclide in soil (Bq / kg); where, enrichment factor (BCF) can be divided into aboveground enrichment factor (BCF) and root enrichment factor (BCF).

[0057] Transfer factor (TF) = Ra activity of aboveground dry weight of plant / Ra activity of underground dry weight of plant.

[0058] The results of the analysis showed that the aboveground parts of the wild pea plant have an effect on... 226 The enrichment coefficient of Ra is -0.69 to 0.75, the enrichment coefficient of the root is 0.94 to 1.04, and the transfer coefficient is 0.68 to 0.76.

[0059] 3) The above-ground parts and roots of the wild pea have an effect on... 226 Ra removal contribution rate determination

[0060] Based on the dry weight of the above-ground parts and roots of the wild pea plant, and the plant's... 226 Ra content was calculated to determine the contribution rate of aboveground removal to total removal, as well as the proportion of aboveground removal to total root removal.

[0061] Nuclide removal amount (Bq) = Dry weight of harvestable portion of plant (kg) × Nuclide content in that portion (Bq / kg);

[0062] The contribution rate of Ra removal by the aboveground parts of pea plant = 100% × (total Ra removed by the aboveground parts and the sum of Ra removed by the aboveground parts and roots of pea plant).

[0063] Computational analysis showed that the aboveground parts of *Vicia sativa* accounted for 83.7%-85.2% of the total Ra removal, and the amount of Ra removed by the aboveground parts was 5.1-5.8 times that of the roots. The aboveground parts of *Vicia sativa* contributed the majority of the total Ra removal by plants, demonstrating the plant-derived Ra removal function of *Vicia sativa* from the soil.

[0064] In the soil 226 Ra activity is strongly influenced by parent material and pollution. In soil 226 Ra typically ranges from a few becquerels per kilogram to several hundred becquerels per kilogram. 226 The global average Ra content ranges from 17 to 60 Bq / kg. For example, China reported values ​​ranging from approximately 2 to 440 Bq Ra / kg, with an average of 32 Bq / kg; Switzerland reported values ​​ranging from 10 to 900 Bq / kg; and the global median activity was 32 Bq / kg (IAEA, 2014). In this trial, the Ra content in the pea remediation plot was only around 0.5 Bq / g, indicating a low level of Ra contamination.

[0065] In conclusion, the legume *Vicia sativa* has... 226 Ra has a high transfer coefficient and enrichment coefficient, and is effective in removing aboveground parts. 226 Ra contribution rate exceeds 80%, indicating that the aboveground part of the pea plant contributes significantly to the soil's... 226 Ra's plant extraction function. The legume *Vicia sativa* is undemanding in terms of soil requirements, has wide adaptability, and strong regeneration ability, making it a suitable material for remediation and treatment. 226 Ra contaminated soil is a promising method.

[0066] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0067] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0068] The above provides a detailed description of the application of wild pea in the remediation of radioactive radium contaminated soil. Specific examples have been used to illustrate the principles and implementation methods of the invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the invention. Therefore, the content of this specification should not be construed as a limitation of the invention.

Claims

1. An application of wild pea in the remediation of radioactive radium-contaminated soil, characterized in that, The application is for 226 The activity concentration of Ra is 200-5000 Bq / kg 226 Ra-contaminated soil; the applications include: exist 226 Wild pea seeds are sown in Ra-contaminated soil and cultivated. Once the wild peas reach maturity, the above-ground parts are removed from the contaminated soil, or the entire plant is removed. The cultivation management includes: […]. 226 The Ra-contaminated soil was leveled, watered, and fertilized. Repeat the above process until the... 226 Ra contaminated soil 226 Ra content meets environmental safety standards; The above-ground parts of the wild pea are... 226 The enrichment factor of Ra is 0.69-0.75; The roots of the wild pea 226 The enrichment factor of Ra is 0.94-1.04; The above-ground parts of the wild pea are... 226 The enrichment activity concentration of Ra was 351-365 Bq / kg, and the roots of the wild pea were used for... 226 The enrichment activity concentration of Ra is 480-518 Bq / kg.

2. The application according to claim 1, characterized in that, The 226 Ra-contaminated soil is a weakly acidic contaminated soil from a subtropical monsoon climate zone.

3. The application according to claim 2, characterized in that, The 226 The pH value of Ra-contaminated soil is 5-6.

4. The application according to claim 1, characterized in that, The sowing rate of wild pea seeds is 3-5 kg / mu.

5. The application according to claim 1, characterized in that, The fertilization construction refers to the... 226 Base fertilizer was applied before planting the wild peas in Ra-contaminated soil, and top fertilizer was applied during the growth of the wild peas.

6. The application according to claim 5, characterized in that, Both the base fertilizer and the top dressing are nitrogen, phosphorus, and potassium compound fertilizers.

7. The application according to claim 1, characterized in that, Watering construction according to the above 226 The water shortage situation of Ra-contaminated soil was investigated, so that the... 226 The soil moisture content of Ra-contaminated soil remains at 40%-70% of field capacity.

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