A method for targeted removal of aquatic plants and ecological synchronous restoration of water body based on a compound composition

Abstract

The application discloses a kind of aquatic plant directional removal and water body ecological synchronous repair method based on complex composition, belong to water body ecological management and environmental protection technical field, including the following steps: using unmanned aerial vehicle patrol to combine manual sampling mode, the crazy growth area of target submerged plant, dense degree and growth state are defined, water body is divided into sparse area and dense area, the target submerged plant coverage of sparse area is 30% and below, the target submerged plant coverage of dense area is 30% or more;Special water treatment composition used in the application, by the synergistic effect of core active ingredient and selective synergist, target submerged plant such as golden fish algae, fox tail algae shows very high inhibitory activity, and has little effect on non-target submerged plant such as Vallisneria, black algae and aquatic animals such as zebra fish.The indiscriminate damage of traditional broad-spectrum chemical agents to the ecological chain of water body is avoided, and the biodiversity and ecological stability of the treated water body are effectively maintained.

Description

Technical Field

[0001] This invention relates to the field of water body ecological management and environmental protection technology, specifically a method for targeted removal of aquatic plants and simultaneous restoration of water body ecology based on a compound composition. More specifically, it relates to a systematic method for targeted removal of excessively proliferating submerged plants in still or slow-flowing water bodies such as lakes, reservoirs, landscape ponds, and slow-flowing rivers, while simultaneously achieving water environment restoration and ecological health improvement. Background Technology

[0002] With the increasing prominence of eutrophication in water bodies, submerged plants, especially dominant species such as *Ceratophyllum demersum* and *Myriophyllum spicatum*, often experience explosive growth in aquatic environments. Their excessive reproduction clogs waterways, reduces water flow, depletes dissolved oxygen, and the decomposition of dead plant matter exacerbates the endogenous release of nutrients, ultimately leading to water quality deterioration and ecosystem degradation, severely impacting the landscape, ecology, and usability of aquatic bodies. Therefore, efficiently and safely controlling the excessive growth of these aquatic plants and promoting aquatic ecological restoration has become an urgent and important issue in environmental governance. Current technologies for controlling the excessive growth of submerged plants in aquatic bodies mainly employ physical, chemical, and ecological control methods, but all have their limitations and struggle to simultaneously achieve control efficiency, ecological safety, and long-term stability.

[0003] Physical removal technology, which mainly involves manually or mechanically harvesting, cutting, and removing aquatic plants, is the most widely used emergency remediation method. This method typically only removes the above-ground parts of the plants, failing to completely remove their underwater roots and stolons, leading to plant debris residue and rapid regeneration, resulting in a high recurrence rate. Large-scale mechanical operations can violently agitate bottom sediment, causing the resuspension of deposited nitrogen, phosphorus, and other pollutants, leading to secondary pollution. Simultaneously, the operation poses a direct risk of physical damage to non-target aquatic organisms and their habitats. As a temporary measure, it requires continuous and intensive investment of manpower and resources, resulting in high long-term maintenance costs.

[0004] Chemical remediation technologies primarily rely on broad-spectrum herbicides such as quaternary ammonium salts, organophosphates, or copper-based herbicides, which kill plants through their physiological toxicity. These herbicides often lack selectivity, severely toxicizing other beneficial aquatic plants, plankton, and aquatic animals like fish, shrimp, and crabs while targeting the target plants, thus disrupting aquatic biodiversity and ecological balance. Some herbicides are difficult to translocate to plant roots, failing to achieve complete eradication, and residual roots and stems easily lead to recurrence. Furthermore, some chemical herbicides are stable and degrade slowly in water; they themselves or their degradation products may possess ecotoxicity, posing residual pollution and long-term environmental risks.

[0005] Ecological regulation techniques aim to competitively suppress target plants by restoring or constructing healthy aquatic ecosystems, such as by planting competing plants, introducing filter-feeding animals, or regulating nutrients. However, this method is slow to respond, and the restoration and balancing of the ecosystem often takes months or even longer, making it unsuitable for handling explosive ecological crises. Its effectiveness is significantly influenced by various environmental factors such as water temperature, light, and water depth, resulting in poor controllability and stability. In water bodies where the target plants have already achieved absolute ecological dominance, introduced competing species struggle to establish themselves and exert their effects, leading to limited and uncertain governance outcomes.

[0006] In summary, existing technologies for addressing the problem of excessive submerged plant growth generally suffer from contradictions in balancing rapid removal with ecological safety, radical cure with cost control, and immediate response with long-term stability. Therefore, we propose a method for targeted removal of aquatic plants and simultaneous ecological restoration of aquatic bodies based on a compound formulation, in order to alleviate or resolve these problems.

[0007] The information disclosed above in this background section is only for enhancing the understanding of the background section of this invention, and therefore may include prior art that is not known to those skilled in the art. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a method for targeted removal of aquatic plants and simultaneous restoration of aquatic ecosystems based on a compound composition, thereby resolving issues such as low treatment efficiency, high risk of ecological damage, poor selectivity, easy recurrence, secondary pollution, and delayed response in existing technologies.

[0009] To achieve the above objectives, the present invention provides a method for targeted removal of aquatic plants and simultaneous restoration of aquatic ecosystems based on a compound composition, comprising the following steps:

[0010] S1. Using a combination of drone patrols and manual sampling, the area of ​​rampant growth, density and growth status of target submerged plants are identified, and the water body is divided into sparse and dense areas. The coverage of target submerged plants in the sparse area is 30% or less, and the coverage of target submerged plants in the dense area is more than 30%.

[0011] S2. Test the dissolved oxygen concentration, nitrogen and phosphorus concentration, and pH value of the water. The criteria for judgment are that the dissolved oxygen concentration is not less than 3 mg / L and the pH value is 6.5-8.5. Subsequent pesticide application operations can only be carried out after the conditions are met.

[0012] The tests include measuring dissolved oxygen concentration, nitrogen and phosphorus concentration, and pH value in the water. The criteria for determining whether the dissolved oxygen concentration is not less than 3 mg / L, the pH value is 6.5-8.5, the total nitrogen is ≤2.0 mg / L, and the total phosphorus is ≤0.4 mg / L. Subsequent chemical application can only proceed if these conditions are met. If the above indicators do not meet the standards, water pretreatment should be carried out by means of aeration and pH adjustment until the indicators meet the requirements before proceeding with subsequent operations.

[0013] S3. A water treatment composition for targeted removal of target aquatic plants is formulated, the composition comprising synergistically effective amounts of an aryloxyphenoxypropionic acid compound or an agriculturally acceptable ester or salt thereof (component A) and phytic acid or a salt thereof (component B).

[0014] S4. Based on the zoning results of step S1, dilute the water treatment composition described in step S3 into a working solution of appropriate concentration, and apply it to the target aquatic plants by directional spraying. The application amount and spraying parameters are adjusted according to the plant density and growth status.

[0015] S5. Seven to ten days after applying the water treatment composition, the dead or withered target aquatic plants are salvaged and removed.

[0016] S6. After the salvage and removal, add ecological restoration materials to the treated water body to improve the bottom sediment and promote the restoration of a healthy aquatic ecosystem;

[0017] S7. Regularly monitor the dissolved oxygen concentration, nitrogen and phosphorus concentration, and recurrence of target submerged plants in the water, and adjust the treatment strategy in real time.

[0018] Preferably, in step S3, the water treatment composition further comprises a surfactant (component C) and an environmentally responsive degradation promoter (component D), wherein component D comprises an organic acid and a soluble metal salt.

[0019] Preferably, component C is an alkyl glycoside or an organosilicon surfactant; the organic acid in component D is citric acid and / or ascorbic acid, and the soluble metal salt is an iron salt and / or a manganese salt.

[0020] Preferably, in step S4, the directional spraying is carried out by positioning the nozzle 10-20 cm above the canopy of the target plant, with the spraying direction forming an angle of 30 to 60 degrees with the plant stem, and controlling the droplet size to be 150-300 micrometers.

[0021] Preferably, in step S4, the effective concentration of component A in the working solution in the sparse area is 0.3-0.6 ppm, and in the dense area it is 0.6-1.2 ppm, depending on the plant density of the treatment zone.

[0022] Preferably, in step S1, the target aquatic plant is a submerged plant, including Ceratophyllum demersum and / or Myriophyllum spp.

[0023] Preferably, in step S6, the ecological restoration substrate comprises indigenous microbial agents and adsorbent materials, including a complex of microbial agents of nitrifying bacteria and denitrifying bacteria and modified biochar.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] The specialized water treatment composition used in this invention employs aromatic phenoxypropionic acid compounds as its core active ingredient. This composition inhibits the activity of acetyl-CoA carboxylase (ACCase) in target submerged plants, blocking the synthesis of fatty acids and thus inhibiting plant cell division and growth. Combined with phytic acid or its salts as a selective synergist, the two produce a significant synergistic effect, exhibiting extremely high inhibitory activity against target submerged plants such as *Ceratophyllum demersum* and *Myriophyllum spicatum*, while having minimal impact on non-target submerged plants such as *Vallisneria natans* and *Hydrilla verticillata*, as well as aquatic animals such as zebrafish. This fundamentally avoids the indiscriminate destruction of the aquatic ecosystem caused by traditional broad-spectrum chemical agents, effectively maintaining the biodiversity and ecological stability of the treated water bodies.

[0026] The surfactants in the specialized composition enhance the adhesion and penetration of active ingredients on plant surfaces, ensuring effective delivery of the pesticide to the plant roots. Combined with the inhibitory effect of aryloxyphenoxypropionic acid active ingredients on fatty acid synthesis in the root tip meristem, it can kill the target plant at its source. Field trials have demonstrated that the inactivation rate of the target plant, *Ceratophyllum demersum*, exceeded 90% one week after application. With harvesting during the window period, the overall removal rate exceeded 99%, and no recurrence was observed during the subsequent 90-day monitoring period. This completely overcomes the high recurrence problem caused by physical harvesting that only removes the above-ground parts and traditional chemical pesticides that do not kill the roots.

[0027] The method of this invention takes only 7-10 days from application of the pesticide to the optimal harvesting window, and can complete the removal of plants and initial improvement of water quality in the target area within 2-4 weeks. The treatment cycle is significantly shorter than that of conventional ecological regulation technology, which can quickly respond to the explosive growth of aquatic plants and promptly curb the trend of ecological deterioration.

[0028] The environmentally responsive degradation promoter in the composition of this invention can accelerate the natural photolysis and microbial degradation of the active ingredients after their action is completed, with a short half-life and no persistent residue. On the other hand, the precise application process reduces the loss of the agent into the water and sediment, and the timely removal of plant residues during the determined optimal retrieval window avoids water hypoxia and endogenous pollution caused by the decay of the residues, thus ensuring the environmental friendliness of the treatment process itself.

[0029] The composition of this invention, due to its high efficacy, requires a low dosage per unit area and avoids repeated treatments through its radical cure. Combined with precise application and optimized dredging, the overall treatment cost is significantly lower than the cost of long-term physical dredging or subsequent chemical pollution treatment. This method is applicable to various still or slow-flowing water bodies such as lakes, reservoirs, landscape ponds, and slow-moving rivers, and exhibits unique advantages, especially in sensitive water areas with high requirements for the protection of non-target organisms.

[0030] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the invention will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0031] Figure 1 This is a flowchart of the eco-friendly method for targeted removal of aquatic plants and improvement of the aquatic environment according to the present invention. Detailed Implementation

[0032] 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. It should be noted that the drawings are schematic and not illustrated to scale. For clarity and convenience, the relative sizes and proportions of the parts shown in the drawings have been exaggerated or reduced in size. Any size is only illustrative and not limiting.

[0033] Example 1: Indoor bioassay to verify the synergistic selectivity and safety of the compound composition.

[0034] 1. Test materials

[0035] Target plant: Ceratophyllum demersum, collected from natural water bodies, pre-cultured in the laboratory for one week, and selected healthy plants with consistent growth status.

[0036] Non-target plants: Vallisneria natans (common submerged plant), Phragmites australis (seedlings, emergent plant).

[0037] Test animal: zebrafish (Danio rerio, standard test organism), body length approximately 3.0 ± 0.5 cm.

[0038] Test reagents:

[0039] A water treatment composition for targeted removal of aquatic plants: by weight percentage, it comprises 2% quizalofop-P-ethyl ester (component A, aryloxyphenoxypropionic acid compound, calculated as acid), 1% sodium phytate (component B), 2% alkyl glycoside (APG, component C), 3% environmentally responsive degradation promoter composed of citric acid and ascorbic acid (mass ratio 2:1) and ferric sulfate (0.5%) (component D), with the balance being kaolin, and is formulated as a water-dispersible granule.

[0040] Comparison agent: Commercially available broad-spectrum herbicides commonly used in water bodies, whose main component is quaternary ammonium salt, used at the recommended concentration.

[0041] Blank control: Deionized water.

[0042] 2. Test Methods

[0043] Phytotoxicity test: Hydroponic method was used. Fresh weight 5.0 g of *Ceratophyllum demersum* and *Vallisneria natans* were placed in glass jars containing 5 L of standard dilution water. The following treatments were set up: ① Blank control; ② Single agent A (1.0 ppm); ③ The composition of this invention (A concentration 1.0 ppm, B / C / D in proportion); ④ Commercially available control agent (at recommended concentration). Each treatment was replicated in triplicate. Plant morphological changes were observed and recorded on days 1, 3, and 7 after treatment. The fresh weight of each treatment was measured on day 7, and the fresh weight inhibition rate was calculated.

[0044] Acute toxicity test in fish: Zebrafish were placed in beakers containing 3L of test solution, with 10 fish per group. Setup: ① Blank control; ② Composition of the present invention (A concentration 1.0 ppm); ③ Composition of the present invention (A concentration 5.0 ppm, 5 times the application concentration); ④ Commercially available control agent (at the recommended concentration). Observations were conducted continuously at (25±1)℃ for 96 hours, and mortality rates were recorded.

[0045] 3. Experimental results, among which the selectivity for plants is shown in Table 1.

[0046] Table 1. Results of plant selectivity

[0047] Where *SI = bitter grass EC 50 / Ceratophyllum demersum EC 50 A higher value indicates a stronger selectivity.

[0048]

[0049] Table 1 shows that single agent A has a strong inhibitory effect on both *Ceratophyllum demersum* and *Vallisneria natans*, but poor selectivity. The composition of this invention maintains an extremely high inhibition rate against *Ceratophyllum demersum*, while the inhibition rate against *Vallisneria natans* drops sharply to 5.1%, with a selectivity index as high as 19.25, demonstrating unexpectedly high selectivity. Commercially available control agents, on the other hand, have almost no selectivity and cause serious damage to non-target plants.

[0050] Safety for fish:

[0051] During the 96-hour observation period, all zebrafish in the blank control group, the 1.0 ppm group, and the 5.0 ppm group of the composition of this invention survived and exhibited normal activity. In contrast, all zebrafish in the commercially available control group died within 48 hours.

[0052] In summary, the composition of the present invention remains safe for zebrafish, a model fish, even at concentrations five times higher than those used conventionally, while commercially available agents exhibit strong toxicity, highlighting the significant advantage of the present invention in terms of ecological safety.

[0053] Example 2: Application of the full-process method in the field, the process is as follows (see attached diagram). Figure 1 As shown

[0054] This embodiment was conducted in the area of ​​a goldfish algae bloom in a landscape lake in a city. The landscape lake has an area of ​​about 2 hectares and an average water depth of 1.5 meters.

[0055] 1. Implementation Background

[0056] The lake area is approximately 4000m in some areas. 2 The coverage of hornwort reached 40-60%, the water flow was poor, the dissolved oxygen was low, the test result was 2.8 mg / L, and the water quality was classified as worse than Class V.

[0057] 2. Targeted removal and aquatic environment improvement methods, including the following steps:

[0058] S1. Aerial photography was conducted using a drone equipped with a multispectral camera. The distribution of *Ceratophyllum demersum* was retrieved through the vegetation index (NDVI) and verified by manual sampling.

[0059] A dense and sparse area was defined, with a coverage of 30% as the boundary. The dense area is approximately 2500m². 2 Coverage >30%, sparse area approximately 1500m 2 Coverage ≤30%.

[0060] S2. The test showed that the dissolved oxygen was 2.8 mg / L, slightly lower than the standard of 3 mg / L. Therefore, two solar-powered aerators were installed in the planned application area. After 48 hours of continuous aeration, the dissolved oxygen rose to 3.5 mg / L and the pH value was 7.2, meeting the application conditions.

[0061] S3. Using the composition of the present invention described in Example 1, prepare a stock solution of 5 ppm (calculated as A) for later use.

[0062] For densely populated areas: Dilute the mother liquor to obtain a working solution of 1.0 ppm (as A). Use a dedicated waterborne operation vessel equipped with an adjustable spray boom, controlling the nozzle to be positioned approximately 15 cm above the hornwort canopy, with the nozzle angled downwards at 45 degrees, for uniform spraying. The application rate is approximately 300 L / ha, or 30 mL / m². 2 .

[0063] For sparse areas: dilute the mother liquor to obtain a working solution of 0.5 ppm (as A), spray in the same way as dense areas, and apply at a rate of approximately 200 L / hectare.

[0064] To prevent hypoxia, the 4000m 2 The area is divided into north and south zones, and the pesticides are applied in batches every three days.

[0065] S4. On the 3rd day after application, the tips of the *Ceratophyllum demersum* leaves began to turn pale green; on the 7th day after application, over 90% of the *Ceratophyllum demersum* plants turned yellow and became inactive, with the coverage of surviving plants dropping to less than 10%. Most of the inactive plants softened and entered the floating stage, reaching the optimal harvesting window; the main harvesting was completed on the 7th-10th day after application, and supplementary harvesting was carried out on the 14th day to clean up any remaining plants. A total of approximately 8 tons of fresh *Ceratophyllum demersum* were harvested and removed, with good integrity and few fragments.

[0066] S5. One week after the dredging is completed, ecological restoration substrate is evenly applied to the treated area. This substrate consists of modified straw biochar loaded with locally selected nitrifying / denitrifying compound microbial agent (1×10⁸ CFU / g), with a particle size of 2-4 mm, and an application rate of 50 kg / hectare. At the same time, seedlings of native submerged plants such as Vallisneria natans and Potamogeton crispus are replanted along the lake shore.

[0067] S6. During the treatment period and for 3 months after treatment, key indicators were monitored weekly. The treatment results are shown in Table 2.

[0068] Table 2 Comparison before and after treatment

[0069]

[0070] As shown in Table 2, the composition of this invention completely kills the target *Ceratophyllum demersum* within 7-10 days. Combined with optimized harvesting, the removal rate is nearly 100%, with no recurrence within three months. Throughout the entire treatment process, no poisoning or death was observed in non-target aquatic plants or fish, thus protecting biodiversity. Through synergy, key indicators such as dissolved oxygen, transparency, and total phosphorus in the water body continued to improve, and the water quality steadily improved from below Grade V to Grade III-IV.

[0071] Example 3: Through laboratory formulation experiments, the optimal ratio range was determined based on the synergistic effect of core components A and B in the composition according to the present invention.

[0072] 1. Test materials

[0073] Test target: Ceratophyllum demersum, hydroponic standardized plant.

[0074] Non-target organism tested: Hydrilla verticillata (a common submerged plant).

[0075] Experimental setup: A two-factor, three-level completely randomized design was adopted.

[0076] Factor A (component A concentration): 0.25 ppm, 0.5 ppm, 1.0 ppm, calculated as quizalofop-p-ethyl.

[0077] Factor B (component B concentration): 0 ppm (single-agent control), 0.25 ppm, 0.5 ppm, calculated as phytic acid.

[0078] Component C (APG, 0.05%) and component D (base amount) were added at fixed levels.

[0079] Each treatment was set to be repeated 4 times, for a total of 9 treatment groups.

[0080] Measurement indicators: After 7 days of treatment, the fresh weight of the plants was measured, and the fresh weight inhibition rate was calculated. The synergistic coefficient was calculated using the Abbott formula. SR > 1.25 indicated significant synergy, SR < 0.75 indicated antagonism, and values ​​in between indicated additive effects.

[0081] 2. Test Results

[0082] Table 3. Inhibitory effect on *Ceratophyllum demersum*

[0083]

[0084] In all treatments combining A and B, the fresh weight inhibition rate of Elodea was less than 8%, and there was no significant difference compared with the single-agent A treatment (P>0.05), indicating that the addition of component B did not increase the toxicity to non-target submerged plants.

[0085] In summary, the addition of component B produced a strong synergistic effect on the herbicidal activity of component A. Specifically, when A was at 0.5 ppm, its inhibition rate against *Ceratophyllum demersum* was 35.8% when used alone, while the addition of 0.25 ppm B increased the inhibition rate to 78.9%, with a SR of 2.2. This synergistic effect was particularly pronounced in the A:B ratio range of 1:0.5 to 2:1.

[0086] Example 4 verifies the effect of the precise application process parameters in this invention on improving drug utilization and reducing loss.

[0087] 1. Experimental Design

[0088] Simulation system: Construct a transparent water tank with a length × width × height of 2m × 1m × 1m, with a 5cm thick standard bottom mud, and plant goldfish algae at a uniform density.

[0089] Test variables:

[0090] Spraying distance (D): 5 cm, 10 cm, 15 cm, 20 cm.

[0091] Spraying angle (θ): 90° vertically downwards, 45° diagonally downwards, 0° parallel to the plant.

[0092] Test method: Methylene blue was used as a substitute for the chemical solution, and spraying was performed using a controllable nozzle. The droplet trajectory and deposition state were recorded using an underwater high-definition camera. Samples were collected immediately after spraying from different water layers and the surface of the sediment. The concentration of the dye was determined using a spectrophotometer, and the deposition rate of the chemical solution on the target plants, the suspension rate in the water column, and the adhesion rate to the sediment were calculated.

[0093] Under the optimal parameter combination, the composition of the present invention (A 0.8 ppm) was used in actual efficacy tests, and the results were compared with those obtained using non-optimal parameters. The test results are shown in Table 4.

[0094] Table 4. Distribution Characteristics of Drug Solution

[0095]

[0096] As shown in Table 4, spraying too close a distance results in high-speed water flow impacting the sediment, causing a large amount of pesticide to adhere to the sediment. This wastes pesticide, increases environmental risks, and ultimately leads to poor control. When the spraying distance is 10-15 cm and the angle is 30-60 degrees downwards, the pesticide deposition rate on the target plants is the highest, while the adhesion rate to the sediment is the lowest. This achieves efficient pesticide utilization with minimal environmental disturbance, resulting in the best control effect. Spraying too far away or at a parallel distance increases the proportion of droplets suspended in the water column, making them easier to disperse and reducing the effective deposition per unit area.

[0097] Example 5: Applications for different water body types and complex polluted water bodies

[0098] 1. Overview of the Implementation Location

[0099] The river channel is about 15 meters wide, the treated section is 100 meters long, the average water depth is 0.8 meters, and the flow velocity is <0.05 m / s.

[0100] Main problems: ① A mixed outbreak of *Ceratophyllum demersum* and *Myriophyllum spicatum*, with a coverage rate of 50%; ② Slight water pollution, COD... Mn The concentration of nitrogen in the sediment was 8.5 mg / L, the concentration of ammonia nitrogen was 1.2 mg / L, and the hardness was relatively high, approximately 180 mg / L; ③ The sediment was black and had a slight odor.

[0101] 2. Challenging Adjustments and Implementation

[0102] Challenge 1: High water hardness may affect the effectiveness of the agent. Therefore, 0.01% disodium ethylenediaminetetraacetate (EDTA-2Na) was added as a water softener to chelate calcium and magnesium ions, ensuring the stability and activity of each component in the composition.

[0103] Challenge 2: Slow flow may cause pesticide drift. Adjust the spraying operation to be against the water flow direction and use a fan-shaped nozzle to reduce the application width and ensure that the pesticide has sufficient contact time in the target area.

[0104] Challenge 3: Complex Pollution. The base material for the ecological restoration step is adjusted to a combination of composite functional microbial agents and phosphate-adsorbent modified zeolite, making it more targeted. Other steps are performed according to the method of this invention.

[0105] 3. Implementation Results

[0106] Treatment results: From day 8 to 11 after application, large quantities of *Ceratophyllum demersum* and *Myriophyllum spicatum* floated to the surface, and their removal was successful. After 30 days, the target plant removal rate was >95%. By the end of the 90-day observation period, only a very small number of new plants were found in dead water areas.

[0107] Water transparency improved from 25 cm to 60 cm. Dissolved oxygen steadily increased from 2.5 mg / L to 6.0 mg / L. Ammonia nitrogen decreased from 1.2 mg / L to 0.3 mg / L. Sixty days after adding remediation substrate to the bottom sediment, the sediment color changed from black to grayish-brown, and the odor disappeared. No fish or shrimp deaths were observed during the treatment process. After treatment, the species and number of bottom-dwelling aquatic insects increased, indicating an improvement in the bottom habitat.

[0108] In summary, even in slow-flowing rivers with high hardness and complex pollution, the method of this invention can still be successfully implemented through adaptive fine-tuning, achieving the expected targeted removal and ecological improvement goals. This demonstrates the universality, flexibility, and powerful problem-solving capabilities of the technical solution of this invention, proving that it is not only applicable to ideal, enclosed landscape water bodies.

[0109] Example 6: Synergistic effect and safety verification of cyhalofop-butyl compound composition

[0110] 1. Test materials

[0111] The target plant was *Ceratophyllum demersum*, the non-target plant was *Vallisneria natans*, and the test animal was zebrafish. The test agent was a water treatment composition, which, by weight percentage, contained 2% cyhalofop-butyl (component A, aryloxyphenoxypropionic acid), 1% sodium phytate (component B), 2% alkyl glycoside (component C), 3% environmentally responsive degradation promoter composed of citric acid and ascorbic acid (mass ratio 2:1) and ferric sulfate (0.5%) (component D), with the balance being kaolin, and was prepared as a water-dispersible granule.

[0112] 2. The test methods are the same as those for the plant toxicity test and fish acute toxicity test in Example 1.

[0113] 3. Test Results

[0114] After 7 days of treatment, the fresh weight inhibition rate of Elodea was 97.5%, and the fresh weight inhibition rate of Vallisneria natans was 4.8%, with a selectivity index of 18.9. All zebrafish in the 1.0 ppm and 5.0 ppm concentration groups survived for 96 hours with no abnormal activity, and there was no difference from the blank control group.

[0115] Comparative Example 1: Compared with traditional physical and mechanical salvage methods

[0116] 1. Implementation Location and Background

[0117] The selected site is adjacent to Example 2, has the same aquatic plant community, and all water quality was below Grade V before treatment. The area covered by *Ceratophyllum demersum* is approximately 40%, covering an area of ​​about 4000 m². 2 Another similar landscape lake area serves as a contrasting area.

[0118] 2. Implementation Steps

[0119] The implementation was carried out concurrently with Example 2. The equipment used included manual boat propellers, hand-held long-handled sickles, and mechanical harvesting boats.

[0120] The first phase of intensive salvage lasted for five days, using mechanical harvesting boats to cut and collect the goldfish algae within a 0-50cm range below the water surface. For shallow water areas near the shore that were inaccessible to machinery, manual removal with sickles was employed.

[0121] Routine maintenance and dredging continued for three months, with two manual inspections and sporadic dredging operations per week to remove newly grown plants and debris left over from previous dredging. Water quality and ecological monitoring were conducted concurrently with Example 2. The implementation results are shown in Table 5.

[0122] Table 5 Evaluation Data Table

[0123]

[0124] As shown in Table 5, traditional physical salvage methods only address the symptoms, failing to eradicate the root system and leading to rapid recurrence. They also cause significant physical disturbance and direct damage to the aquatic ecosystem during operation, and incur high long-term maintenance costs. This contrasts sharply with the thorough, stable, low-cost, and eco-friendly results achieved in Embodiment 2 of this invention through chemical eradication, optimized salvage, and ecological restoration.

[0125] Comparative Example 2: Compared with conventional broad-spectrum chemical herbicides such as quaternary ammonium salts.

[0126] 1. Implementation Design

[0127] The experiment was conducted in a large, controlled outdoor cement pool measuring 10m × 5m × 1.2m. The pool was lined with bottom mud, and a simplified aquatic ecosystem was simulated and constructed, which included planting the target plant *Ceratophyllum demersum*, the non-target submerged plant *Hydrilla verticillata*, and releasing 10 local crucian carp and snails.

[0128] The commonly available commercially available 20% double quaternary ammonium salt solution, registered for use in water bodies, was selected and applied at the concentration recommended by the product. After diluting the solution according to the instructions, it was evenly sprinkled throughout the pond. Subsequent changes were monitored. The results are shown in Table 6.

[0129] Table 6 Comparison of the effects of quaternary ammonium salt herbicides

[0130]

[0131] As shown in Table 6, while conventional broad-spectrum chemical agents have short-term killing effects on target plants, they lack selectivity and severely damage non-target aquatic animals and plants, leading to a break in the aquatic food chain. They cannot eradicate target plants and have a high recurrence rate. Simultaneously, they cause water quality deterioration and the risk of secondary algal blooms. This is vastly different from the high selectivity, fish safety, complete eradication, and continuous water quality improvement effects demonstrated in Examples 1 and 2 of this invention.

[0132] Comparative Example 3: Using only the single active ingredient of this invention

[0133] 1. Implementation Design

[0134] The site setup is the same as the densely populated area in Example 2, selecting a 2500m² area with similar conditions. 2 area.

[0135] The agent used only component A (ethyl quizalofop-P-ethyl aryl aroxyphenoxypropionic acid compound) from the composition of this invention, excluding components B, C, and D. A 5 ppm stock solution was prepared and diluted to a 1.0 ppm working solution. Conventional, extensive spraying was employed. Only the agent was applied; the zoning strategy, optimized harvesting window, and subsequent ecological restoration measures of this invention were not implemented. The implementation results are shown in Table 7.

[0136] Table 7 Comparison of Results

[0137]

[0138] As shown in Table 7, even if the basic active substances of this invention are used, the final effect will be greatly reduced if the key synergistic components B, C, and D, as well as the matching precise processes and system procedures, are missing. It may even degenerate into a common chemical treatment method that still poses ecological risks and only treats the symptoms, not the root cause.

[0139] 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 present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0140] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for targeted removal of aquatic plants and simultaneous ecological restoration of aquatic bodies based on a compound composition, characterized in that, Includes the following steps: S1. Using a combination of drone patrols and manual sampling, the area of ​​rampant growth, density and growth status of target submerged plants are identified, and the water body is divided into sparse and dense areas. The coverage of target submerged plants in the sparse area is 30% or less, and the coverage of target submerged plants in the dense area is more than 30%. S2. Test the dissolved oxygen concentration, nitrogen and phosphorus concentration, and pH value of the water. The criteria for judgment are that the dissolved oxygen concentration is not less than 3 mg / L and the pH value is 6.5-8.

5. Subsequent pesticide application operations can only be carried out after the conditions are met. S3. A water treatment composition for targeted removal of target aquatic plants is formulated, the composition comprising synergistically effective amounts of an aryloxyphenoxypropionic acid compound or an agriculturally acceptable ester or salt thereof (component A) and phytic acid or a salt thereof (component B). S4. Based on the zoning results of step S1, dilute the water treatment composition described in step S3 into a working solution of appropriate concentration, and apply it to the target aquatic plants by directional spraying. The application amount and spraying parameters are adjusted according to the plant density and growth status. S5. Seven to ten days after applying the water treatment composition, the dead or withered target aquatic plants are salvaged and removed. S6. After the salvage and removal, add ecological restoration materials to the treated water body to improve the bottom sediment and promote the restoration of a healthy aquatic ecosystem; S7. Regularly monitor the dissolved oxygen concentration, nitrogen and phosphorus concentration, and recurrence of target submerged plants in the water, and adjust the treatment strategy in real time.

2. The method according to claim 1, characterized in that, In step S3, the water treatment composition further comprises a surfactant (component C) and an environmentally responsive degradation promoter (component D), wherein component D comprises an organic acid and a soluble metal salt.

3. The method according to claim 2, characterized in that, Component C is an alkyl glycoside or an organosilicon surfactant; the organic acid in component D is citric acid and / or ascorbic acid, and the soluble metal salt is an iron salt and / or a manganese salt.

4. The method according to any one of claims 1-3, characterized in that, In step S4, the specific method of directional spraying is as follows: the nozzle is positioned 10-20 cm above the canopy of the target plant, the spraying direction is at an angle of 30 to 60 degrees to the plant stem, and the droplet size is controlled at 150-300 micrometers.

5. The method according to claim 4, characterized in that, In step S4, based on the plant density of the treatment zone, the effective concentration of component A in the working solution in the sparse zone is 0.3-0.6 ppm, and in the dense zone it is 0.6-1.2 ppm.

6. The method according to any one of claims 1-5, characterized in that, In step S1, the target aquatic plant is a submerged plant, including Ceratophyllum demersum and / or Myriophyllum spp.

7. The method according to claim 1, characterized in that, In step S6, the ecological restoration substrate is a modified adsorbent material loaded with indigenous microbial agents, wherein the indigenous microbial agents contain an effective viable count ≥1×10⁻⁶. 8 A compound inoculant of nitrifying and denitrifying bacteria with a CFU / g concentration, using modified biochar as the adsorbent, with a substrate addition rate of 30-80 kg / hectare.

8. A specific water treatment composition for carrying out the method according to any one of claims 1-7, characterized in that, The composition comprises a synergistically effective amount of an aryloxyphenoxypropionic acid compound or an agriculturally acceptable ester or salt thereof (component A), phytic acid or a salt thereof (component B), a surfactant (component C), and an environmentally responsive degradation promoter (component D); wherein component C is an alkyl glycoside or an organosilicon surfactant, and component D comprises citric acid and / or ascorbic acid, iron salt and / or manganese salt; wherein the aryloxyphenoxypropionic acid compound is selected from at least one of quizalofop-p-ethyl, cyhalofop-butyl, haloxyfop-methyl, and quizalofop-p-ethyl.

9. The special water treatment composition according to claim 8, characterized in that, Based on the total weight of the composition, the content of component A is 0.1-10%, the content of component B is 0.05-5%, the content of component C is 0.5-5%, and the content of component D is 1-5%.

10. The use of the specialized water treatment composition of claim 8 or 9 in the selective removal of submerged plants from water bodies.

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