Cultivation method and application of hornwort for eutrophic pollution abatement in complex water body

Abstract

The invention relates to the technical field of water body pollution treatment, and discloses a hornwort cultivation method for eutrophic pollution treatment under a complex water body and application, the hornwort cultivation method comprises the following steps: S1, plant selection: obtaining hornwort plants with consistent shapes and sizes, and treating the growing parts of the hornwort plants for subsequent experiments; s2, preparing a nutrient solution: preparing the nutrient solution suitable for growth of hornwort for providing necessary growth conditions; s3, preparing a micro-plastic solution: adding micro-plastic into the nutrient solution to form a culture solution with a target concentration for an exposure experiment; s4, setting an experimental environment: setting a container specification and the experimental environment, and ensuring the stability of the test. By optimizing the cultivation method of hornwort and regulating and controlling the environment, the removal capacity of hornwort on total nitrogen and total phosphorus in a complex water body and the adsorption and fixation effect of hornwort on microplastics are improved, and meanwhile, the growth stability and adaptability are enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of water pollution control, and in particular to a method and application of cultivating hornwort for eutrophic pollution control in complex water bodies. Background Art

[0002] Eutrophication pollution is an ecological problem caused by excessive accumulation of nutrients such as nitrogen and phosphorus in water bodies. It is usually manifested as a decrease in dissolved oxygen in water bodies, massive reproduction of algae and deterioration of water quality, posing a threat to the ecological environment and water resource utilization. In bioremediation technology, Dermatophyte, as an efficient aquatic plant, has been widely studied and applied due to its rapid growth, strong tolerance and significant ability to absorb nitrogen and phosphorus.

[0003] At present, the methods used to cultivate Duckweed mainly focus on optimizing its nutrient supply and growth environment conditions. For example, by improving the culture medium formula and increasing the supply of nutrients such as nitrogen and phosphorus, the rapid growth of Duckweed can be promoted and its ability to remove nitrogen and phosphorus pollutants in eutrophic water bodies can be improved. In addition, the use of photoperiod to regulate the photosynthesis efficiency of Duckweed has shown certain application potential. In the prior art, the nitrogen and phosphorus removal rate of Duckweed has reached a high level under laboratory conditions, laying the foundation for its application in eutrophic pollution control.

[0004] However, the existing methods for cultivating duckweed still have many shortcomings; on the one hand, the existing methods have high requirements for the growth environment of duckweed, and it is easily disturbed by pollutants (such as microplastics) in complex water bodies, which makes it difficult to stabilize its growth state and pollution control effects; on the other hand, although the existing technology performs well in nitrogen and phosphorus removal, it lacks targeted research on emerging pollutants such as microplastics, and the adsorption and fixation capacity of duckweed has not been fully explored; in addition, the existing methods are still insufficient in the coordinated regulation of photoperiod and nutrient supply, resulting in the failure to further optimize the growth rate and control effect of duckweed. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a method and application of cultivating hornwort for eutrophic pollution control in complex water bodies, which solves the problem of unstable cultivation effect of hornwort in complex water environments in the prior art.

[0006] To achieve the above purpose, the present invention is implemented by the following technical scheme: a method for cultivating hornwort for eutrophic pollution control in complex water bodies, comprising the following steps:

[0007] S1. Plant selection: obtain hornwort plants with the same shape and size, and process their growing parts for subsequent experiments;

[0008] S2. Preparation of nutrient solution: preparing a nutrient solution suitable for the growth of hornwort to provide necessary growth conditions;

[0009] S3, microplastic solution preparation: adding microplastics to the nutrient solution to form a culture solution of target concentration for exposure experiments;

[0010] S4. Experimental environment setting: set container specifications and experimental environment to ensure the stability of the test;

[0011] S5, exposure culture: placing the plants in the prepared solution for exposure experiment for a specific period of time;

[0012] S6. Growth and water monitoring: Monitor the growth characteristics of hornwort and indicators in water bodies, and record changes;

[0013] S7. Sample preparation and observation: Process the samples of Ceratophyllum plants after the experiment and observe their characteristics through analytical methods.

[0014] Preferably, the S1 comprises:

[0015] Select plants from a healthy, disease-free population of hornwort;

[0016] Cut the top part of the selected plants to a length of 8 to 12 cm and remove impurities attached to the surface;

[0017] The fresh weight of the selected plants was measured, and the error range was controlled within ±5%;

[0018] The treated plants are temporarily stored in clean water for less than 24 hours to maintain the activity of the plants.

[0019] Preferably, S2 includes:

[0020] Weigh the chemical reagents in the nutrient solution formula, including calcium nitrate, magnesium sulfate, potassium dihydrogen phosphate and trace elements;

[0021] The above reagents were dissolved in deionized water to form a 10% Hoagland nutrient solution;

[0022] Adjust the pH value of the nutrient solution to 6.0-7.5 using dilute hydrochloric acid or dilute sodium hydroxide solution;

[0023] Filter the prepared nutrient solution, remove insoluble matter and seal it for storage. The standby time should be less than 7 days.

[0024] Preferably, S3 includes:

[0025] Spherical polyethylene microplastics (PE-MPs) with a particle size of less than 50 μm were selected;

[0026] Dissolving or evenly dispersing PE-MPs in Hoagland's nutrient solution to form a microplastic solution with a concentration range of 40 to 60 mg / L;

[0027] Maintain a uniform distribution of microplastics in the solution by stirring or sonication;

[0028] After preparation, let the solution stand for at least 1 hour to ensure the stability of the components before putting it into experimental use.

[0029] Preferably, S4 includes:

[0030] Control the experimental temperature to 20-30℃;

[0031] Set the illumination time to 8 to 14 hours and the light intensity to 800 to 1200 LM;

[0032] Keep the water level in the container constant and add ultrapure water if necessary.

[0033] Preferably, S5 includes:

[0034] In a glass container with a size of 25-35 cm x 20-30 cm x 15-25 cm, the hornwort plant is placed in a nutrient solution and cultured for 28-36 days;

[0035] During the culture process, PE-MPs solution is added, and the concentration of PE-MPs solution is 40-60 mg / L.

[0036] Preferably, S6 includes:

[0037] The height of the hornwort plants was measured regularly and the relative growth rate (RGR) was calculated. The RGR range was 25% to 65%.

[0038] Water samples were collected every 3 to 5 days to measure the total nitrogen (TN), total phosphorus (TP), turbidity and dissolved oxygen (DO) in the water body, where the turbidity range was 5 to 50 ntu and the DO range was 5 to 15 mg / L.

[0039] Preferably, the S7 includes:

[0040] Cut the leaves of Ceratophyllum japonicum with an area of ​​5 to 15 cm2 and fix them with 3% glutaraldehyde solution in 100 mM sodium phosphate buffer for 20 hours;

[0041] Dehydrated in stages using graded ethanol (30%, 50%, 70%, 90% and 100%), with each stage lasting 8 to 15 minutes;

[0042] Spray gold onto the sample using a sputtering coater, with a current of 10 to 25 mA and a time of 60 to 120 seconds;

[0043] A scanning electron microscope was used to observe the distribution of microplastic particles on the surface and inside the leaves of Dermatophaga.

[0044] Preferably, the S5 further comprises:

[0045] Cultivate using a light and dark photoperiod, with each cycle lasting 24 hours.

[0046] The present invention also provides an application method of hornwort for treating eutrophic pollution in complex water bodies, including but not limited to treating complex water bodies, wherein the treatment comprises the following steps:

[0047] Putting the goldfish algae obtained by the cultivation method into the target water body;

[0048] Adjust the physical and chemical environment of the target water, including temperature, light intensity and pH value, to make it suitable for the growth of hornwort;

[0049] Using Dermatophyte to absorb and remove eutrophic pollutants, total nitrogen (TN) and total phosphorus (TP) in water bodies;

[0050] Capture and fix microplastic particles with a size less than 50μm in water.

[0051] The present invention provides a method and application of cultivating hornwort for treating eutrophic pollution in complex water bodies. It has the following beneficial effects:

[0052] 1. The present invention ensures the healthy growth and high adaptability of Dermatophaga in complex water conditions through plant screening, standardized nutrient solution preparation, precise microplastic solution configuration and environmental parameter control, laying a solid foundation for subsequent research and practical application.

[0053] 2. Scanning electron microscopy observations showed that the leaf surface and interior of the duckweed cultivated by the present invention can effectively adsorb and fix microplastic particles with a particle size of 50 to 500 nm, showing excellent pollutant capture ability, providing a reliable bioremediation approach for the treatment of microplastic pollution in complex water bodies.

[0054] 3. The goldfish algae cultivated by the present invention showed excellent eutrophication pollution control ability in the experimental environment, and its removal rate of total nitrogen (TN) and total phosphorus (TP) was significantly improved. At the same time, it had significant effects on improving water transparency and increasing dissolved oxygen, verifying its potential application value in eutrophication water treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 Flow chart of the cultivation method of the present invention. DETAILED DESCRIPTION

[0056] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe 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 creative work are within the scope of protection of the present invention.

[0057] Please refer to the attached Figure 1 The embodiment of the present invention provides a method for cultivating hornwort for eutrophic pollution control in complex water bodies, comprising the following steps:

[0058] S1. Plant selection: By obtaining hornwort plants with the same shape and size and processing their growing parts for subsequent experiments, the top growth part of hornwort has a higher growth rate and photosynthesis efficiency. Selecting healthy plants can ensure stability during the experiment. By optimizing the screening and processing process of the plants, the uniformity and repeatability of the experimental plants are improved;

[0059] S2. Preparation of nutrient solution: Prepare a nutrient solution suitable for the growth of Duckweed to provide the necessary growth conditions. The nutrient solution preparation meets the needs of rapid growth and efficient photosynthesis of Duckweed, thereby ensuring the stability and repeatability of the composition of the culture medium, laying the foundation for the healthy growth of the plants in subsequent experiments;

[0060] S3. Microplastic solution preparation: Add microplastics to the nutrient solution to form a culture solution of target concentration for exposure experiments. Through the microplastic solution preparation, a stable and uniform microplastic solution can be obtained, which provides a basis for the accuracy of experimental data;

[0061] S4. Experimental environment setting: Set the container specifications and experimental environment to ensure the stability of the experiment. The experimental environment setting provides a standardized experimental environment and improves the scientificity and comparability of the experiment;

[0062] S5. Exposure culture: The plants are placed in a prepared solution for exposure experiments for a specific period of time. The growth characteristics of Dermatophyllum in different microplastic concentration environments and its ability to purify pollutants in water bodies are studied through long-term exposure experiments.

[0063] S6. Growth and water monitoring: Monitor the growth characteristics of the hornwort and the indicators in the water, and record the changes. The growth and water monitoring comprehensively evaluates the growth status of the hornwort and its impact on the water through multiple indicators to ensure the comprehensiveness and accuracy of the experimental data.

[0064] S7. Sample preparation and observation: The samples of Dermatophyte plants after the experiment were processed and their characteristics were observed through analytical methods. The interaction between Dermatophyte and microplastics was intuitively presented through sample preparation and observation, providing direct evidence for its application in pollution control.

[0065] Please refer to the attached Figure 1 In a preferred embodiment of the present invention, S1 includes:

[0066] Select plants from a group of healthy and disease-free hornworts. Healthy hornworts have higher photosynthesis efficiency and growth capacity, and diseased plants should be prevented from dying or growing abnormally during the experiment, which would affect the reliability of the experimental results.

[0067] Cut the top part of the selected plants to a length of 8 to 12 cm, and remove impurities attached to the surface. The uniform plant length and clean surface conditions provide standardized initial conditions for subsequent experiments, ensuring the comparability of experimental results.

[0068] The fresh weight of the selected plants was measured, and the error range was controlled within ±5%. By accurately measuring the fresh weight of the plants, the scientific nature of the experimental data and the accuracy of subsequent analysis were ensured;

[0069] The treated plants are temporarily placed in clean water for less than 24 hours to maintain the activity of the plants. Preserving the treated plants can ensure that the activity before the experiment is maintained, avoid the loss of plant activity, and ensure the accuracy of the experimental data.

[0070] Please refer to the attached Figure 1 In a preferred embodiment of the present invention, S2 includes:

[0071] Weigh the chemical reagents in the nutrient solution formula, including calcium nitrate, magnesium sulfate, potassium dihydrogen phosphate and trace elements. The nutritional requirements of the hornwort include macroelements (nitrogen, phosphorus, potassium, calcium, magnesium, sulfur) and trace elements (iron, manganese, zinc, copper, molybdenum, boron), which are directly involved in photosynthesis, respiration and biofilm formation. Ensure that the proportions of the various ingredients in the nutrient solution formula are accurate to avoid growth inhibition or nutritional excess of the hornwort due to an imbalance in the proportion of elements;

[0072] Dissolve the above reagents in deionized water to form a 10% Hoagland nutrient solution. Deionized water prevents impurities or metal ions in ordinary water from reacting with the reagents in the nutrient solution, ensuring the chemical stability of the prepared solution and the absorption effect of the hornwort.

[0073] Adjust the pH value of the nutrient solution to 6.0-7.5 using dilute hydrochloric acid or dilute sodium hydroxide solution. This range can ensure that the pH value of the nutrient solution is suitable for the growth environment of the golden hornwort and provide stable conditions for the normal physiological functions of the plant.

[0074] Filter the prepared nutrient solution, remove the insoluble matter and then seal it for storage. The standby time is less than 7 days. Filtering out the insoluble matter can avoid the influence of impurities on the duckweed during the experiment. At the same time, sealing and refrigerating can extend the service life of the solution and avoid the influence of contamination or degradation on the experimental results.

[0075] Please refer to the attached Figure 1 In a preferred embodiment of the present invention, S3 includes:

[0076] Spherical polyethylene microplastics (PE-MPs) with a particle size of less than 50 μm were selected. The selection of a particle size range of less than 50 μm can simulate the real water pollution environment to the greatest extent, ensuring the uniformity of the distribution of microplastics in the experiment and the scientific nature of the experimental results;

[0077] Dissolve or evenly disperse PE-MPs in Hoagland nutrient solution to form a microplastic solution with a concentration range of 40-60 mg / L. The evenly dispersed microplastic solution can better simulate the polluted water environment, allowing the golden duckweed to fully contact the microplastics, making it easier to study its purification ability.

[0078] Maintain uniform distribution of microplastics in the solution through stirring or ultrasonic treatment. Stirring and ultrasonic treatment can increase the kinetic energy of particles in the solution, reduce agglomeration between particles, and ensure uniform dispersion of microplastics.

[0079] After preparation, let the solution stand for no less than 1 hour to ensure that the composition is stable before using it in the experiment. The standing process allows the particle distribution in the solution to stabilize, avoiding fluctuations in particle concentration during the experiment due to insufficient preparation, thereby providing consistent experimental conditions and improving the reliability of experimental results.

[0080] Please refer to the attached Figure 1 In a preferred embodiment of the present invention, S4 includes:

[0081] The experimental temperature was controlled at 20-30°C, which provided a suitable temperature range for the hornwort, promoted its rapid growth, and ensured the standardization of the experimental environment and the consistency of the data.

[0082] The illumination time was set to 8 to 14 hours and the light intensity was set to 800 to 1200 LM. Through the coordination of this illumination time and light intensity, the natural growth environment of Dermatophyte was simulated, thereby improving the activity of the plant and the reliability of the experimental results.

[0083] The water level in the container was kept constant and ultrapure water was added when necessary. Through water level management and ultrapure water replenishment, the stability of the experimental environment was ensured, which provided guarantees for the growth of Dermatophyte and the accuracy of the experimental results.

[0084] Please refer to the attached Figure 1In a preferred embodiment of the present invention, S5 includes:

[0085] In a glass container with a size of 25-35cm×20-30cm×15-25cm, the duckweed plants are placed in a nutrient solution and cultured for 28-36 days. The transparent glass container is convenient for observing the experimental process. The appropriate container size can provide sufficient growth space for the duckweed, while ensuring the controllability and consistency of the experimental conditions. By controlling the culture time and liquid supply, the scientific nature of the experimental results and the healthy growth of the duckweed are ensured.

[0086] PE-MPs solution was added during the culture process with a concentration of 40-60 mg / L. By controlling the concentration and distribution of the microplastic solution, the microplastic pollution environment in real water bodies was simulated to allow the duckweed to fully contact the microplastic particles, thereby ensuring the reliability of the experimental results.

[0087] Please refer to the attached Figure 1 In a preferred embodiment of the present invention, S6 includes:

[0088] Regularly measure the height of the hornwort plant and calculate the relative growth rate (RGR). The RGR range is 25% to 65%. The formula for calculating the relative growth rate is:

[0089]

[0090] By regularly measuring the plant height and calculating the growth rate, the growth status of the hornwort can be quantified, which helps to analyze the effects of different culture conditions on the growth of the hornwort and identify its optimal growth environment.

[0091] Water samples were collected every 3 to 5 days to measure the total nitrogen (TN), total phosphorus (TP), turbidity and dissolved oxygen (DO) of the water body. The turbidity range was 5 to 50 ntu, and the DO range was 5 to 15 mg / L. Uniform sampling ensured the representativeness of the water samples, which facilitated the analysis of the purification ability of duckweed on eutrophic pollutants in water bodies.

[0092] Please refer to the attached Figure 1 In a preferred embodiment of the present invention, S7 includes:

[0093] Cut the leaves of Dermatophyte with an area of ​​5 to 15 cm2, and fix them with 3% glutaraldehyde solution in 100 mM sodium phosphate buffer for 20 hours. Glutaraldehyde is a highly efficient cross-linking agent, which fixes the sample by cross-linking with proteins. The cell structure and surface characteristics of the leaves of Dermatophyte are maintained by the fixation treatment, providing a stable sample state for subsequent dehydration and microscopic observation.

[0094] Dehydration was performed step by step using graded ethanol (30%, 50%, 70%, 90% and 100%), with each dehydration time being 8 to 15 minutes. The step-by-step dehydration method gradually increased the ethanol concentration to gradually replace the water in the sample, thereby reducing the collapse or damage of the cell structure caused by rapid dehydration.

[0095] The sample was sprayed with gold using a sputtering coater, with a current of 10 to 25 mA for 60 to 120 seconds. The surface and interior of the leaves of the golden hornwort contain non-conductive components. The gold spraying treatment can form a uniform conductive layer on the surface of the sample, avoiding image distortion caused by charge accumulation during SEM observation, thereby improving the imaging quality of the sample in SEM observation and ensuring that the distribution of microplastic particles can be accurately presented.

[0096] The distribution of microplastic particles on the surface and inside the leaves of duckweed was observed using a scanning electron microscope. The scanning electron microscope provides high-resolution images that can intuitively present the distribution characteristics of microplastic particles on the surface and inside the leaves of duckweed, providing a scientific basis for the research and development and optimization of microplastic management technologies.

[0097] Please refer to the attached Figure 1 In a preferred embodiment of the present invention, S5 further comprises:

[0098] Cultivated using a light and dark cycle, with each cycle lasting 24 hours, photosynthesis and respiration are the core of the metabolism of duckweed. By simulating the day and night light and dark cycle, the growth conditions in the natural environment can be reproduced to the greatest extent, which can optimize the photosynthetic efficiency and physiological state of the plant, thereby improving the growth rate and adaptability of duckweed, while ensuring the standardization of experimental conditions.

[0099] The present invention also provides an application method of hornwort for treating eutrophic pollution in complex water bodies, including but not limited to treating complex water bodies, wherein the treatment comprises the following steps:

[0100] Putting the goldfish algae obtained by the cultivation method into the target water body;

[0101] Adjust the physical and chemical environment of the target water, including temperature, light intensity and pH value, to make it suitable for the growth of hornwort;

[0102] Using Dermatophyte to absorb and remove eutrophic pollutants, total nitrogen (TN) and total phosphorus (TP) in water bodies;

[0103] Capture and fix microplastic particles with a size less than 50μm in water.

[0104] In order to better understand the present invention, the above contents are described in detail below in conjunction with specific embodiments.

[0105] Example 1: Cultivation of Ceratophyllum after adding microplastics

[0106] Experimental conditions:

[0107] Ceratophyllum plants with a length of 8 to 12 cm were placed in a 10% Hoagland nutrient solution containing 50 mg / L microplastics (particle size less than 50 μm). The lighting time was set to 12 hours, the light intensity to 1000 LM, the temperature to 25°C, and the culture period to 32 days.

[0108] The RGR of Duckweed and the TN and TP removal rates of the water were determined, and the adsorption distribution of microplastics was observed by scanning electron microscopy.

[0109] Experimental results:

[0110] The RGR of Dermatophaga was significantly increased to 48.2%, and the removal rates of TN and TP were increased to 72% and 70%, respectively.

[0111] Scanning electron microscopy showed that microplastic particles were attached to the surface and inside of the leaves in significant quantities, proving that duckweed has a strong ability to adsorb microplastics.

[0112] in conclusion:

[0113] The addition of microplastics significantly improved the growth rate and pollutant management capabilities of duckweed, verifying the promoting effect of microplastics on its growth and purification performance.

[0114] Example 2: Cultivation of Ceratophyllum without Addition of Microplastics

[0115] Experimental conditions:

[0116] Use 8-12 cm long duckweed plants, place them in 10% Hoagland nutrient solution without microplastics, set the lighting time to 12 hours, the light intensity to 1000LM, the temperature to 25°C, and the culture period to 32 days.

[0117] The growth rate (RGR) of Dermatophaga glabra and the removal rates of total nitrogen (TN) and total phosphorus (TP) in water were determined.

[0118] Experimental results:

[0119] The RGR of Dermatophaga was 28.5%, and the removal rates of TN and TP were 60% and 58% respectively, with limited improvement in water transparency.

[0120] No microplastic particles were attached to the leaves of Dermatophaga, and no surface pollutants were found under scanning electron microscopy.

[0121] in conclusion:

[0122] In an environment without added microplastics, the growth of duckweed and its ability to control water pollution were average, lacking targeted improvements.

[0123] Example 3: Cultivation of Ceratophyllum by Combining Light-Dark Cycle and Microplastics

[0124] Experimental conditions:

[0125] The same hornwort and nutrient solution as in Example 2 were used, and a light-dark cycle (12 hours of light + 12 hours of dark) was set, the light intensity was 1000 LM, and the culture period was 32 days.

[0126] Experimental results:

[0127] The RGR of Dermatophaga was further increased to 56.8%, and the removal rates of TN and TP were 75% and 73%, respectively.

[0128] Scanning electron microscopy showed that microplastics were evenly adsorbed and distributed on the leaf surface and inside, and no photoinhibition was observed.

[0129] in conclusion:

[0130] The combination of light-dark cycles and microplastics optimizes the growth environment of duckweed, making it show higher adaptability and pollution management capabilities.

[0131] Example 4: Cultivation of Ceratophyllum without Regulating Light and Dark Cycle

[0132] Experimental conditions:

[0133] The same hornwort and nutrient solution as in Example 2 were used, except that the illumination time was set to 24 consecutive hours, and other conditions remained unchanged.

[0134] Experimental results:

[0135] The RGR of Ceratophyllum was 38.6%, and the removal rates of TN and TP were 65% and 63%, respectively. Some light damage was observed on the leaf surface (leaf discoloration and loose structure).

[0136] Microplastic adsorption was unevenly distributed, with fewer particles attached in some areas.

[0137] in conclusion:

[0138] The lack of regulation of light and dark cycles causes photoinhibition of duckweed under high light conditions, affecting its growth status and pollution control effects.

[0139] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for cultivating hornwort for eutrophic pollution control in complex water bodies, characterized in that: The following steps are involved: S1. Plant selection: obtain hornwort plants with the same shape and size, and process their growing parts for subsequent experiments; S2. Preparation of nutrient solution: preparing a nutrient solution suitable for the growth of hornwort to provide necessary growth conditions; S3, microplastic solution preparation: adding microplastics to the nutrient solution to form a culture solution of target concentration for exposure experiments; S4. Experimental environment setting: set container specifications and experimental environment to ensure the stability of the test; S5, exposure culture: placing the plants in the prepared solution for exposure experiment for a specific period of time; S6. Growth and water monitoring: Monitor the growth characteristics of hornwort and indicators in water bodies, and record changes; S7. Sample preparation and observation: Process the samples of Ceratophyllum plants after the experiment and observe their characteristics through analytical methods.

2. The method for cultivating hornwort for treating eutrophic pollution in a complex water body according to claim 1, characterized in that: The S1 includes: Select plants from a healthy, disease-free population of hornwort; Cut the top part of the selected plants to a length of 8 to 12 cm and remove impurities attached to the surface; The fresh weight of the selected plants was measured, and the error range was controlled within ±5%; The treated plants are temporarily stored in clean water for less than 24 hours to maintain the activity of the plants.

3. The method for cultivating hornwort for treating eutrophic pollution in a complex water body according to claim 1, characterized in that: The S2 includes: Weigh the chemical reagents in the nutrient solution formula, including calcium nitrate, magnesium sulfate, potassium dihydrogen phosphate and trace elements; The above reagents were dissolved in deionized water to form a 10% Hoagland nutrient solution; Adjust the pH value of the nutrient solution to 6.0-7.5 using dilute hydrochloric acid or dilute sodium hydroxide solution; Filter the prepared nutrient solution, remove insoluble matter and seal it for storage. The standby time should be less than 7 days.

4. The method for cultivating hornwort for treating eutrophic pollution in a complex water body according to claim 1, characterized in that: The S3 includes: Spherical polyethylene microplastics (PE-MPs) with a particle size of less than 50 μm were selected; Dissolving or evenly dispersing PE-MPs in Hoagland's nutrient solution to form a microplastic solution with a concentration range of 40 to 60 mg / L; Maintain a uniform distribution of microplastics in the solution by stirring or sonication; After preparation, let the solution stand for at least 1 hour to ensure the stability of the components before putting it into experimental use.

5. The method for cultivating hornwort for treating eutrophic pollution in a complex water body according to claim 1, characterized in that: The S4 includes: Control the experimental temperature to 20-30℃; Set the illumination time to 8 to 14 hours and the light intensity to 800 to 1200 LM; Keep the water level in the container constant and add ultrapure water if necessary.

6. The method for cultivating hornwort for treating eutrophic pollution in complex water bodies according to claim 1, characterized in that: The S5 includes: In a glass container with a size of 25-35 cm x 20-30 cm x 15-25 cm, the hornwort plant is placed in a nutrient solution and cultured for 28-36 days; During the culture process, PE-MPs solution is added, and the concentration of PE-MPs solution is 40-60 mg / L.

7. The method for cultivating hornwort for treating eutrophic pollution in complex water bodies according to claim 1, characterized in that: The S6 includes: The height of the hornwort plants was measured regularly and the relative growth rate (RGR) was calculated. The RGR range was 25% to 65%. Water samples were collected every 3 to 5 days to measure the total nitrogen (TN), total phosphorus (TP), turbidity and dissolved oxygen (DO) in the water body, where the turbidity range was 5 to 50 ntu and the DO range was 5 to 15 mg / L.

8. The method for cultivating hornwort for treating eutrophic pollution in complex water bodies according to claim 1, characterized in that: The S7 includes: Cut the leaves of Ceratophyllum japonicum with an area of ​​5 to 15 cm2 and fix them with 3% glutaraldehyde solution in 100 mM sodium phosphate buffer for 20 hours; Dehydrated in stages using graded ethanol (30%, 50%, 70%, 90% and 100%), with each stage lasting 8 to 15 minutes; Spray gold onto the sample using a sputtering coater, with a current of 10 to 25 mA and a time of 60 to 120 seconds; A scanning electron microscope was used to observe the distribution of microplastic particles on the surface and inside the leaves of Dermatophaga.

9. The method for cultivating hornwort for treating eutrophic pollution in a complex water body according to claim 6, characterized in that: The S5 further comprises: Cultivate using a light and dark photoperiod, with each cycle lasting 24 hours.

10. A method for applying hornwort for treating eutrophic pollution in complex water bodies, characterized in that: The ceratospermum obtained by the cultivation method according to any one of claims 1 to 9 is applied, but not limited to, to the treatment of complex water bodies, wherein the treatment comprises the following steps: Putting the goldfish algae obtained by the cultivation method into the target water body; Adjust the physical and chemical environment of the target water, including temperature, light intensity and pH value, to make it suitable for the growth of hornwort; Using Dermatophyte to absorb and remove eutrophic pollutants, total nitrogen (TN) and total phosphorus (TP) in water bodies; Capture and fix microplastic particles with a size less than 50μm in water.

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