A method for preventing and controlling harmful algae in water bodies by using cypress alcohol and an algae-removing agent

Abstract

The application discloses a method for preventing and controlling harmful algae in water bodies by using cembranolide and an algae-removing agent. Cembranolide is a kind of natural product of monoterpene, has strong iron chelating ability and good cell membrane penetration. Adding cembranolide with a proper concentration in water bodies can effectively inhibit the growth of multiple water bloom and red tide algae such as Microcystis aeruginosa, Skeletonema costatum, Heterosigma akashiwo and Prorocentrum lima. The application has the advantages of easy availability of raw materials, remarkable effect and simple operation, and provides a natural-based solution for harmful algal bloom prevention and control.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection and water pollution control technology, specifically relating to a method for preventing and controlling harmful algae in water bodies using hinokitiol (β-thujaplicin) and its algaecide. Background Technology

[0003] Currently, the most widely used chemical algaecides are synthetic agents such as copper sulfate, potassium permanganate, hydrogen peroxide, and prometryn. While these synthetic algaecides have high algae-killing efficiency, they generally suffer from poor selectivity, high toxicity to non-target aquatic organisms such as fish, crustaceans, and benthic organisms, and tend to remain in water and sediment for extended periods, causing secondary pollution. For example, copper sulfate is toxic to rainbow trout (…). Oncorhynchus mykiss ) 96h-LC 50 Only 0.135 mg / L, for large Daphnia ( Daphnia magna 48h-LC 50 It is only 0.024 mg / L, while its usual concentration (0.5–1 mg / L Cu) is much lower. 2+ The concentration has approached or exceeded the acute lethal concentration for non-target organisms, and long-term use will also cause copper accumulation in bottom sediments and damage to the aquatic ecological structure.

[0004] To overcome the aforementioned drawbacks of synthetic algaecides, developing safe, efficient, and low-toxicity natural algaecides from terrestrial and aquatic plants has become an important research direction in the field of aquatic algal bloom control. Plant secondary metabolites reported to have algicidal activity mainly include phenolic acids, fatty acids, alkaloids, flavonoids, and terpenes. Among these, monoterpenes have attracted increasing attention due to their small molecular weight, wide availability, good biodegradability, and high environmental compatibility. However, currently developed natural algaecides generally suffer from problems such as high algicidal concentrations, unsatisfactory broad-spectrum algicidal effects against common algal blooms and red tides, and unclear target specificity. Therefore, discovering novel, highly efficient natural algaecides with low toxicity to non-target organisms and significant control effects against common algal blooms and red tides is of great significance for the prevention and control of harmful algae in aquatic bodies. Summary of the Invention

[0005] The technical problem to be solved by this invention is to find a safe, environmentally friendly, and highly efficient natural algaecide with low toxicity to non-target aquatic organisms, in order to solve the problem of frequent occurrence of harmful algae in water bodies.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, the present invention proposes a method for preventing and controlling harmful algae in water using juniper alcohol, the method comprising adding juniper alcohol to the water.

[0007] The juniper alcohol is a monoterpene compound with tropolone as the parent nucleus and isopropyl substitution thereon, and its molecular formula is C. 10 H 12 O2, with a molecular weight of 164.2 and CAS number 499-44-5.

[0008] Furthermore, the water body in question is a water body where algae are about to erupt or have already erupted.

[0009] Furthermore, the juniper alcohol is natural juniper alcohol, synthetic juniper alcohol, or a salt, ester, or complex derivative based on retaining the cycloheptatrienolone core of juniper alcohol.

[0010] Optionally, the natural juniper alcohol is extracted from plant essential oils, while the synthetic juniper alcohol is obtained through chemical or biological synthesis.

[0011] Optionally, the plant essential oil comprises cypress essential oil.

[0012] Furthermore, harmful algae include one or more of the following: *Microcystis aeruginosa*, *Skeletonema costatum*, *Heterosigma erythroplasma*, and *Prorocentrum lima*. *Microcystis aeruginosa*, when in freshwater, can cause cyanobacterial blooms. *Skeletonema costatum*, *Heterosigma erythroplasma*, and *Prorocentrum lima*, when in seawater, can cause red tides.

[0013] Furthermore, juniper alcohol was used to control algal blooms dominated by Microcystis aeruginosa, with an effective dosage concentration of 1–10 mg / L.

[0014] Furthermore, cypress alcohol was used to control red tides dominated by Skeletallopithecus costatus, with an effective dosage concentration of 5–15 mg / L. Furthermore, cypress alcohol was used to control red tides dominated by Heterosigma erythroplasma and / or Prorocentrum rimae, with an effective dosage concentration of cypress alcohol of 10–15 mg / L.

[0015] Juniper alcohol, through its strong iron chelation and high lipid solubility, transports iron ions from the water into algal cells, causing intracellular Fe... 2+ Excessive accumulation triggers the Fenton reaction, generating excessive reactive oxygen species, which in turn induces lipid peroxidation of algal cell membranes, damage to chloroplast and mitochondrial structures, and decline in photosynthetic system function, ultimately achieving highly efficient inhibition of harmful algae.

[0016] Cypress alcohol exhibits target specificity, inhibiting the growth of harmful algae while also being effective against zebrafish (…). Danio rerio 96h-LC50 =30.123 mg / L) and large daphnia ( Daphnia magna ,48h-LC 50 Non-target aquatic organisms (e.g., 10.418 mg / L) exhibit low acute toxicity, and the safety ratio (LC50) for Microcystis aeruginosa is [not specified]. 50 / IC 50 The values ​​are 43.7 and 15.1 respectively.

[0017] Furthermore, formulations containing juniper alcohol can be in one or more of the following forms: powder, liquid, aqueous solution, suspended sustained-release granules, and sustained-release bags. Methods of use include, but are not limited to, direct application of the solution, hanging of the sustained-release bag, and administration of the sustained-release granules.

[0018] Secondly, the present invention provides an algaecide comprising juniper alcohol.

[0019] Furthermore, the algaecide is in the form of powder, liquid agent, aqueous solution, suspended slow-release granules, or slow-release bag.

[0020] The beneficial effects of this invention are: 1. The juniper alcohol used in this invention is a monoterpene compound naturally occurring in cypress trees. The raw materials for synthesis are readily available and exhibit excellent environmental compatibility. It has a small molecular weight, is easily soluble in common organic solvents, and has a stable molecular structure, facilitating large-scale production, transportation, and application.

[0021] 2. The juniper alcohol used in this invention has a significant inhibitory effect on a variety of harmful algae. In freshwater bodies, 0.690 mg / L of juniper alcohol can significantly inhibit the growth of Microcystis aeruginosa (72h-ICP). 50 Its algae-inhibiting efficiency is superior to that of the existing commercial algaecide, prometryn (72h-IC). 50 =1.573 mg / L); In seawater, juniper alcohol also has a low half-maximal inhibitory concentration (MCC) against a variety of red tide algae, such as Skeletalella costatum, Heterosigma erythrosporum, and Protoporphyra lima.

[0022] 3. The acute toxicity of juniper alcohol used in this invention to non-target aquatic organisms is significantly lower than its effective algae-inhibiting concentration. Its effect on zebrafish (… Danio rerio ) 96h-LC 50 The concentration was 30.123 mg / L, for large Daphnia (… Daphnia magna 48h-LC 50 The safety ratio (LC50) for Microcystis aeruginosa was 10.418 mg / L. 50 / IC 50The concentrations of copper sulfate and copper sulfate can reach 43.7 and 15.1 respectively, which are much higher than those of traditional chemical algaecides such as copper sulfate, making them effective in inhibiting harmful algae while maintaining good ecological safety for aquatic animals. Attached Figure Description

[0023] Figure 1 The effects of cypress alcohol at a concentration of 10 mg / L on 7 harmful algae (Skeletonema costatum). S. costatum Gloydial Phaeocystis P. globosa Karenia mikimotoi K. mikimotoi East China Sea Prorocentrum P. donghaiense Red Tide Heterobacterium H. akashiwo limnea P. lima Microcystis aeruginosa M. aeruginosa Preliminary screening results of inhibition rate at 72h.

[0024] Figure 2 The dose-response curves of juniperol at 72 h are shown for Microcystis aeruginosa, Skeletonus costatus, Heterosigma erythrosporum, and Protoporphyromonas limma. Among them, a is the dose-response curve of juniperol at 72 h for Microcystis aeruginosa, b is the dose-response curve of juniperol at 72 h for Skeletonus costatus, c is the dose-response curve of juniperol at 72 h for Heterosigma erythrosporum, and d is the dose-response curve of juniperol at 72 h for Protoporphyromonas limma.

[0025] Figure 3 For cypress alcohol to zebrafish ( Danio rerio ) and large daphnia ( Daphnia magna The dose-response curves of juniper alcohol in zebrafish at 96 h and the dose-response curve of juniper alcohol in Daphnia magna at 48 h are shown in the figure.

[0026] Figure 4 The images show the changes in cell morphology and ultrastructure of *Skeletonema costatum* after treatment with juniperol; where a represents the changes in cell morphology of *Skeletonema costatum* after treatment with juniperol, collected by light microscopy, and b represents the changes in ultrastructure of *Skeletonema costatum* after treatment with juniperol, collected by transmission electron microscopy.

[0027] Figure 5 The changes in photosynthetic pigments and photosynthetic parameters of *Skeletonema costatum* after treatment with juniperol are shown. Among them, a represents the change in chlorophyll a of *Skeletonema costatum* after treatment with juniperol, b represents the change in chlorophyll c of *Skeletonema costatum* after treatment with juniperol, c represents the change in carotenoids of *Skeletonema costatum* after treatment with juniperol, d represents the change in the maximum photochemical quantum yield (Fv / Fm) of PSⅡ of *Skeletonema costatum* after treatment with juniperol, e represents the change in light energy utilization efficiency (α) of *Skeletonema costatum* after treatment with juniperol, and f represents the change in the maximum relative electron transport rate (rETRmax) of *Skeletonema costatum* after treatment with juniperol.

[0028] Figure 6 The effects of different treatments (CK: iron-containing medium control; CK-Fe: iron-deficient medium control; HK: iron-containing medium + cypressin; HK-Fe: iron-deficient medium + cypressin) on the growth of *Skeletonema costatum*; where a) is a comparison of the color of the algal solution after 72 h of culture of *Skeletonema costatum*, and b) is the Fe content of *Skeletonema costatum* cells. 3+ Prussian blue staining.

[0029] Figure 7 Comparison of various parameters of *Skeletonema costatum* under different treatments (CK: iron-containing medium control; CK-Fe: iron-deficient medium control; HK: iron-containing medium + cypressin; HK-Fe: iron-deficient medium + cypressin); a) Comparison of cell density of *Skeletonema costatum*; b) Comparison of total iron content of *Skeletonema costatum*; c) Comparison of Fe content of *Skeletonema costatum*. 2+ Content comparison chart.

[0030] Figure 8 The changes in reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD) activity, and glutathione (GSH) content in *Skeletonema costatum* cells after treatment with juniper alcohol were shown. Specifically, a represents the change in ROS content in *Skeletonema costatum* cells after juniper alcohol treatment, b represents the change in MDA content, c represents the change in SOD activity, and d represents the change in glutathione content. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solutions in this application, the present invention will be further described below with reference to embodiments. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0032] In this embodiment of the invention, juniper alcohol (purity ≥99%, CAS No. 499-44-5) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. (Aladdin). Dimethyl sulfoxide (DMSO) was used as the solvent to prepare the stock solution. The prepared stock solution was added to the corresponding algal culture medium to dilute the juniper alcohol to the required test concentration. The final volume ratio of DMSO in the system did not exceed 0.1% (v / v). Preliminary experiments confirmed that 0.1% (v / v) DMSO had no significant effect on the growth of the tested algae. In specific implementations, dimethyl sulfoxide only serves as a solubilizer and can also be other organic solvents and alkaline aqueous solutions, such as ethanol and diethyl ether.

[0033] In the algal culture medium, the marine algae (Skeletonema costatum, Phaeocystis globosa, Karenia mikimotoi, Protodinium donghaiense, Heterosigma erythrosporum, Protodinium limmaense) were cultured in f / 2 medium, and the freshwater algae (Microcystis aeruginosa FACHB-905) were cultured in BG11 medium. The culture conditions were 20 ℃ and a light-dark cycle of 12 h:12 h. All algal cells in the logarithmic growth phase were used for the experiment.

[0034] Example 1: Preliminary screening of the algicidal activity of cypress alcohol against eight harmful algae In this embodiment, *Skeletonema costatum* ( S. costatum Initial density 1.2 × 10 5 cells / mL), spherical brown algae ( P. globosa 1.3×10 5 cells / mL), Karenia mikimotoi ( K. mikimotoi 9.4×10 3 cells / mL), Prorocentrum donghaiense ( P. donghaiense 4.8×10 4 cells / mL), Heterobacterium erythrorhizon ( H. akashiwo 3.0×10 4 cells / mL), Protodinium limae ( P. lima 8.0×10 3 cells / mL) and Microcystis aeruginosa ( M. aeruginosa 5.0×10 5 Using algal cultures (cells / mL) as the test subject, juniper alcohol was added to each well (10 mL / well, 6-well plate) in the logarithmic growth phase to a final concentration of 10 mg / L. An equal volume of 0.1% (v / v) DMSO was used as a solvent control. Each treatment was performed in triplicate. After 72 h of culture, the algal cultures were fixed with Lugol's solution, and the algal cell density was counted using a hemocytometer and an optical microscope (Eclipse Ni-U, Nikon®). The inhibition rate was calculated using the following formula: Inhibition rate IR (%) = (1 - N) t / N c ) × 100% Where N t To treat the algal cell density of the group, N c The algal cell density represents the control group. Results are shown below. Figure 1 .

[0035] The results showed that 10 mg / L juniper alcohol had a significant inhibitory effect on four harmful algae: *Microcystis aeruginosa*, *Skeletonema costatum*, *Heterosigma erythroplasma*, and *Prorocentrum limeri*. The inhibition rate against *Microcystis aeruginosa* and *Skeletonema costatum* exceeded 90%. However, it was insensitive to *Phaeocystis globosa*, *Prorocentrum donghaiense*, and *Karenella mikimotoi* at this tested concentration. These results preliminarily indicate that juniper alcohol is a novel natural algicidal agent with a broad-spectrum inhibitory effect on common algae blooms and red tides, while also possessing certain target specificity.

[0036] Example 2: Dose-response relationship test of cypress alcohol on Microcystis aeruginosa, Skeletalella costatum, Heterosigma erythrosporum, and Prorocentrum limma This embodiment further determined the dose-response relationship of cypressin in the four sensitive algae (Microcystis aeruginosa, Skeletalella costatum, Heterosigma erythrosporum, and Protoporphyra limma) screened in Example 1, and calculated their 72-hour half-maximal inhibitory concentration (IC50). 72h-50 ).

[0037] The specific method is as follows: A series of concentration gradients of juniper alcohol were added to the logarithmic growth phase algal solutions (10 mL / well, 6-well plate) of four algae species, with 0.1% (v / v) DMSO as the solvent control. Each treatment was performed in triplicate. After 72 h of cultivation, the inhibition rate at each test concentration was calculated according to the method in Example 1. The dose-inhibition rate data were curve-fitted using a probit regression model in SPSS 31.0 software to determine the IC50. 72h-50 And its 95% confidence interval, the results are shown in Figure 2 .

[0038] Depend on Figure 3 It is evident that juniperol exhibits the strongest inhibitory effect on Microcystis aeruginosa, with an IC50 value of [missing value]. 72h-50 At only 0.690 mg / L, it is significantly lower than that of the existing commercially available synthetic algaecide, prometryn (EC). 72h-50 =1.573 mg / L); IC50 against three algae: Skeletalella costatum, Heterosigma erythrosporum, and Prorocentrum limmae. 72h-50 The concentrations of juniper alcohol were 4.286, 7.161, and 7.733 mg / L, respectively, all at relatively low levels, which can achieve efficient algae suppression in practical water applications. Preferably, juniper alcohol at a concentration of not less than 0.690 mg / L is used to control algal blooms dominated by Microcystis aeruginosa; juniper alcohol at a concentration of not less than 4.286 mg / L is used to control red tides dominated by Skeletallopithecus costatus; juniper alcohol at a concentration of not less than 7.161 mg / L is used to control red tides dominated by Heterosigma redtraceae; and juniper alcohol at a concentration of not less than 7.733 mg / L is used to control red tides dominated by Prorocentrum limeris.

[0039] Example 3: Acute toxicity test of cypress alcohol on zebrafish and Daphnia magna To evaluate the ecological safety of cypress alcohol as an algaecide for aquatic bodies, this embodiment tested the effects of cypress alcohol on common non-target aquatic organisms such as zebrafish ( Danio rerio ) and large daphnia ( Daphnia magna Acute toxicity of 0.1% (v / v) DMSO was investigated. Preliminary experiments confirmed that 0.1% (v / v) DMSO had no significant effect on the survival of zebrafish and Daphnia magna. In the zebrafish experiment, healthy adult zebrafish were exposed to a series of concentration gradients of juniper alcohol solution (static water method), with three replicates per treatment and five fish per replicate. Mortality was continuously observed and recorded over four days. In the Daphnia magna experiment, healthy adult Daphnia magna were exposed to a series of concentration gradients of juniper alcohol solution, with three replicates per treatment. Mortality was continuously observed and recorded every 24 hours within 48 hours. SPSS 31.0 software was used to fit the dose-mortality data using a probit regression model to determine the LC50. 50 And its 95% confidence interval, the results are shown in Figure 3 .

[0040] Depend on Figure 3 It is evident that the acute toxicity of juniper alcohol to zebrafish and Daphnia magna was significantly lower than its inhibitory concentrations on Microcystis aeruginosa and Skeletallopithecus costatus. Its effect on zebrafish (… Danio rerio ) 96h-LC 50 The concentration was 30.123 mg / L, for large Daphnia (… Daphnia magna 48h-LC 50 The concentration was 10.418 mg / L. The safety ratio (LC50) of cypressin for zebrafish was determined using *Microcystis aeruginosa* as the target. 50 / IC 50 =43.7) and the safety ratio for large daphnia (LC) 50 / IC 50 =15.1) are significantly higher than those of commonly used copper sulfate (whose conventional concentration is 0.5–1 mg / L Cu). 2+ (The concentration has approached or exceeded the acute lethal concentration for fish and large daphnia). This result demonstrates that cypress alcohol, as a natural algaecide, exhibits good ecological safety for non-target aquatic organisms while inhibiting harmful algae.

[0041] Example 4: Study on the inhibitory mechanism of juniper alcohol on Skeletallopithecus costatus To elucidate the algicidal mechanism of juniperol, this example uses *Skeletonema costatum* as the model algae and treats 100 mL of algae with an initial density of 1.2 × 10⁻⁶ mg / L juniperol. 5In the logarithmic growth phase of *Skeletonema costatum*, cells / mL were used as a control, with 0.1% (v / v) DMSO as the solvent. Each treatment was performed in triplicate. After 72 h of treatment, the algicidal mechanism of juniper alcohol was analyzed from multiple perspectives, including morphology, photosynthetic system, iron homeostasis, and oxidative stress.

[0042] 1. Cell morphology and ultrastructure Observation of the treated algal cells under an optical microscope (Eclipse Ni-U, Nikon®, ×400) and a transmission electron microscope (HT7820, Hitachi®) revealed that the *Skeletonema costatum* cells in the juniper alcohol-treated group showed obvious rupture and disintegration, and damage to chloroplasts and mitochondria such as atrophy and destruction of the inner membrane structure (see [link to article]). Figure 4 ).

[0043] 2. Photosynthetic pigments and photosynthetic parameters The content of photosynthetic pigments was determined by acetone extraction, and photosynthetic parameters were measured after 20 min of dark adaptation using a portable modulated chlorophyll fluorometer (MINI-PAM-II, Walz®). The results showed that after 24 h of treatment with juniper alcohol, the contents of chlorophyll a, chlorophyll c, and carotenoids in *Skeletonema costatum* cells were significantly reduced; the maximum photochemical quantum yield (Fv / Fm) and light energy utilization efficiency (α) of PSII were significantly decreased, while the maximum relative electron transport rate (rETRmax) did not change significantly (see [link to original text]). Figure 5 ).

[0044] 3. Steady-state changes in iron To verify whether juniperol inhibits algal growth by disrupting iron homeostasis through iron chelation, this study included four treatment groups: CK (iron-deficient f / 2 medium + 0.1% DMSO), CK-Fe (iron-deficient f / 2 medium + 0.1% DMSO), HK (iron-deficient f / 2 medium + 7 mg / L juniperol), and HK-Fe (iron-deficient f / 2 medium + 7 mg / L juniperol). After 72 h of culture, intracellular Fe was observed using Prussian blue staining. 3+ Intracellular total iron and Fe were quantitatively determined using a colorimetric kit (Elabscience Biotech). 3+ Content. Results showed (see...) Figure 6 ): (1) Iron deficiency alone for 72 h had no significant effect on the growth of Skeletallopithecus costatus (CK vs CK-Fe); (2) Under iron-containing conditions, juniperol significantly inhibited algal growth (HK), but under iron-deficient conditions, the algal inhibitory activity of juniperol completely disappeared (HK-Fe vs HK), indicating that iron is a necessary condition for juniperol to exert its algal inhibitory effect; (3) Prussian blue staining and quantitative results both showed that the total iron and Fe in the HK group cells were significantly lower than those in the HK group. 2+The content was significantly higher than that of the other three groups, proving that juniper alcohol can transport a large amount of iron ions in the water and accumulate them in algal cells.

[0045] 4. Changes in oxidative stress indicators Intracellular reactive oxygen species (ROS) levels were detected using the fluorescent probe DCFH-DA; MDA content, SOD activity, and GSH content were measured using commercial kits. Results showed (see...). Figure 8 After 72 h of treatment with juniper alcohol, the following were observed in the cells of *Skeletonema costatum*: (1) ROS levels increased significantly, indicating that juniper alcohol induced excessive production of reactive oxygen species in the cells; (2) MDA content increased significantly, indicating that significant membrane lipid peroxidation damage occurred in the cell membrane; (3) SOD activity and GSH content also increased significantly, indicating that even with the activation of the antioxidant system, the cells still failed to completely remove the excessive ROS induced by juniper alcohol, ultimately leading to the accumulation of oxidative damage and algal cell death.

[0046] 5. Summary of Algae Inhibition Mechanism Based on the above results, this embodiment reveals for the first time a novel algicidal mechanism of cypress alcohol based on "iron chelation-iron overload-oxidative damage": (1) Cypress alcohol, with its strong iron chelation ability and good lipid solubility, binds iron ions (Fe) in the water to iron ions (Fe) 3 + (1) Transported and accumulated into algal cells; (2) Excessive Fe in cells 2+ Triggering the Fenton reaction (Fe 2+ + H2O2 → Fe 3+ +OH· + OH - (2) Excessive ROS generates a large amount of highly active ROS such as hydroxyl radicals; (3) Excessive ROS triggers membrane lipid peroxidation (MDA increases), activates but ultimately breaks through the antioxidant defense system (SOD, GSH increases), thereby damaging the membrane structure and function of algal cell chloroplasts and mitochondria (photosynthetic pigment content, Fv / Fm and α decrease), ultimately leading to algal cell death. This mechanism of action is different from the existing natural algaecides, which mainly work by directly destroying the photosystem II electron transport chain or activating programmed cell death, providing a new approach for the development of natural algaecides.

Claims

1. A method for preventing and controlling harmful algae in water using juniper alcohol, characterized in that, Add juniper alcohol to the water.

2. The method for preventing and controlling harmful algae in water using juniper alcohol according to claim 1, characterized in that, The water body in question is one that is about to erupt or has already erupted with algae.

3. The method for preventing and controlling harmful algae in water using juniper alcohol according to claim 1, characterized in that, The juniper alcohol is natural juniper alcohol, synthetic juniper alcohol, or a salt, ester, or complex derivative based on the cycloheptatrienolone core of juniper alcohol.

4. The method for preventing and controlling harmful algae in water using juniper alcohol according to claim 1, characterized in that, Harmful algae include one or more of Microcystis aeruginosa, Skeletalella costatum, Heterosigma erythrium, and Protodinium limma.

5. A method for preventing and controlling harmful algae in water using juniper alcohol according to claim 4, characterized in that, Juniper alcohol was used to control algal blooms dominated by Microcystis aeruginosa. The effective dosage of juniper alcohol was 1–10 mg / L.

6. A method for preventing and controlling harmful algae in water using juniper alcohol according to claim 4, characterized in that, The effective dosage of juniper alcohol for controlling red tides dominated by Skeletallopithecus costatus is 5–15 mg / L.

7. A method for preventing and controlling harmful algae in water using juniper alcohol according to claim 4, characterized in that, The effective dosage concentration of juniper alcohol for controlling red tides dominated by Heterobrycota erythropoiesis and / or Prorocentrum erythropoiesis is 10–15 mg / L.

8. A method for preventing and controlling harmful algae in water using juniper alcohol according to claim 1, characterized in that, Formulations containing juniper alcohol include one or more of the following: powder, liquid, aqueous solution, suspended sustained-release granules, and sustained-release pouches.

9. An algaecide, characterized in that, The algaecide contains juniper alcohol.

10. An algaecide according to claim 9, characterized in that, The algaecide is available in the form of powder, liquid, aqueous solution, suspended slow-release granules, and slow-release bags.

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