RU2818195C2 - Compositions for controlling phytoplankton pollution - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: group of inventions relates to a composition for weakening, inhibiting and/or eliminating the growth of phytoplankton in a water body, comprising granules containing: 80.0–99.5 wt.% of active substance with specific gravity of more than 1.0 g/ml, which includes algicide based on peroxide, copper or aluminum or a combination thereof; and 0.5–20.0 wt.% of hydrophobic coating material with specific gravity less than 1.0 g ml, which includes a fatty acid or derivative thereof, wax, paraffin, rosin, silicone derivative or a combination thereof, wherein the active substance is encapsulated with a hydrophobic coating material. Also disclosed is a method of preventing and/or inhibiting the development of toxic phytoplankton bloom in a water body by adding said composition to a portion of the water body, having a toxic biomass of phytoplankton above 8,000 cells/ml or chlorophyll concentration above 3 mcg/l.

EFFECT: group of inventions provides gradual release of algicide along the water column (due to the use of granules which, after being introduced into the water body, first settle and then float).

22 cl, 20 dwg, 2 tbl, 11 ex

Description

Field of technology

[001] The present invention describes compositions for cost-effectively reducing phytoplankton blooms in water.

State of the art

[002] Under favorable conditions, not yet fully defined, the growth rate of the dominant phytoplankton species increases, resulting in a significant increase in its biomass, a process often called a "bloom". Increasing toxic phytoplankton blooms, which can cover large areas, are of growing concern to communities, water authorities and environmental scientists around the world. The production of various toxins by these organisms poses a serious threat to the quality of water in lakes and reservoirs and their use for drinking water, recreational activities and irrigation. It is clear that approaches currently used to limit toxic blooms, such as watershed management (to reduce nutrient inputs), are expensive and unsuccessful.

[003] Approximately 300 species of phytoplankton cyanobacteria (often called blue-green algae), such as Microcystis species and microalgae, are known to form massive blooms, many of which produce large amounts of toxic chemicals. Due to the massive consumption of O ₂ through respiration, blooms can cause O ₂ depletion and mass mortality of fish and fauna, and clogging of water pumps and filters. Annual global losses associated with these blooms amount to many billions of US dollars (US Environmental Protection Agency (US EPA), Compilation of cost data associated with the impacts and control of nutrient pollution, 2015).

[004] Cyanobacteria are photosynthetic (Gram-negative) bacteria. Many species of cyanobacteria produce and then release toxins (also known as "cyanotoxins") into the water either towards the end of the bloom or under physical pressure (such as filtration or pumping) (Huisman, et al., Nature Rev Microbiol 16: 471- 483, 2018). Research has shown that cyanotoxins cause death and various illnesses in people and animals that drink, swim or even eat something that has been exposed to contaminated water. Cyanotoxins are not sensitive to boiling and can be subjected to extremely strong chlorination for drinking. The World Health Organization (WHO) recommends prohibiting the consumption or recreational use of water containing toxic cyanobacterial biomass exceeding 10 µg/L chlorophyll a (WHO, Guidelines for Drinking-Water Quality, Addendum to Volume 2, Health Criteria and Other Supporting Information, 1998) and can reach levels of up to 1100 µg/L chlorophyll a (Bertone et al. Environ Microbiol 9: 1415-1422, 2018; Often et al. Environmental Science and Technology 46: 3480-3488, 2012; Huisman (ibid.) ). In addition, when cyanobacteria bloom, huge amounts of polysaccharides are released into the water, making it viscous. This phenomenon is also sometimes associated with "swimmer's itch" due to the itching that occurs when coming into contact with contaminated water. This further creates operational problems for water utilities, which regularly encounter clogged pipes, as well as for agricultural producers, preventing them from using drip irrigation systems.

[005] Microalgae are a heterogeneous group of eukaryotic photosynthetic microorganisms that includes several groups, including green algae, red algae, brown algae, diatoms and dinoflagellates. They cause clogged pipes in reservoirs used for irrigation or wastewater storage tanks. Some algae species (e.g. Prymnesium spp., Karenia spp., Alexandrium spp. and others) are toxic and have also been responsible for widespread fish kills in aquaculture and the marine environment. Illnesses and even deaths have sometimes been reported among people and animals who have consumed toxic water or seafood contaminated with algal toxins.

[006] Most phytoplankton blooms worldwide are treated with copper salts, such as copper sulfate pentahydrate (CuSO ₄ ⋅ 5H ₂ O, CAS No. 7758-99-8, “copper”), a relatively safe and effective algaecide that causes algae lysis. However, in water with high organic loads, mineral content, or pH levels above pH 7.0, its effectiveness is dramatically reduced.

[007] Other less commonly used algaecides rely on hydrogen peroxide (H ₂ O ₂ ) either through direct application or by releasing it from various compounds such as percarbonates. Cyanobacteria are much more sensitive to H ₂ O ₂ than most microalgae (Drabkova et al. Environ Sci Technol 41: 309-314, 2007). Thus, H ₂ O ₂ treatments affect toxic cyanobacteria while having much less impact on other algae.

[008] Because fish and some other aquatic organisms are sensitive to H ₂ O ₂ , the US EPA requires that the lake not be completely treated in one day, which will allow these organisms to escape to untreated areas.

[009] The mechanism of action of H ₂ O ₂ involves the triggering of oxidative stress. Thus, it can trigger an autocatalytic cascade of signals leading to cell death (Berman-Frank et al., Environ Microbiol 9: 1415-1422, 2007; Spungin et al., Biogeosciences 15: 3893-3908 2018) among a population of cyanobacteria.

[010] There is a huge age-related difference in the ability of the cyanobacterium Microcystis spp. to break down H ₂ O ₂ because its breakdown by older cells occurs much faster than in younger cells (Daniel et al, Environmental Microbiology Reports 11: 621-629, 2019). Toxic strains _are less able to destroy _H2O2 than non-toxic strains (Schuurmans, Harmful Algae 78: 47-55, 2018).

[011] Currently used _H2O2 treatment protocols _for Microcystis species blooms are based on _{single H2O2} treatments up to 0.7-1 mM (Zhou, Chemosphere 211: 1098-1108 2018; Matthijas et al Water Research 46: 1460-1472, 2012). All currently used algaecide applications have 3 detrimental disadvantages: (i) dose; (ii) duration of application and (iii) cost of application.

[012] Current algal bloom treatment protocols using various granular algaecides are ineffective due to the immediate settling of particles into sediments. Thus, the time of exposure of phytoplankton to the active substance (AI) is quite short. Consequently, very high concentrations are used with serious consequences for the environment.

[013] Even when a solution of copper or hydrogen peroxide (in liquid form) is added, specialized equipment is required and installed on boats. For example, lake Delftse hout (Netherlands) with an area of ~200,000 ^m2 and a volume of 705,000 ^m3 was contaminated with toxic Anabaena species and was treated with 5 ppm. 50% liquid H ₂ O ₂ , which amounted to 3.5 tons, and application took 5 hours (Tsiarta et al., 2017). In another attempt to treat a toxic Alexandrium bloom at Ouwerkerkse Kreek (Netherlands), a 420,000 m ³ reservoir, treatment took two days, during which 21 tons of 50% liquid H ₂ O ₂ were applied. The direct costs of this attempt amounted to 370,000 euros (Burson et al., Harmful Algae 31: 125-135, 2014). In addition, special measures were taken to store concentrated H ₂ O ₂ (delivery on the day of application by a certified transport company; storage in a closed area with access only by permission). These types of applications are always performed by professionals experienced in handling chemicals. The complexity and cost associated with these treatments have reduced the number of treatment candidates almost exclusively to reservoirs smaller than 100,000 ^m2 (Lurling et al., Aquat Ecol 1-21, 2015) and even then requiring long treatment times, including mobilization and demobilization specified equipment, connections and personnel.

[014] The duration of processing is a critical element of its success. Recently developed remote sensing technologies (Kudela, et al., Remote Sens Environ 167: 196–205, 2015) coupled with in situ measurements allow early recognition of cyanobacterial populations well before mass blooms develop (Bertone (ibid); Hmimina et al., Water Res 148: 504-514, 2019). Due to the presence of phycobilins (with selective absorption spectra) and the absence of chlorophyll b in cyanobacteria, it is possible to recognize the presence of cyanobacteria (Bertone (ibid); Hmimina (ibid).

[015] Currently used treatments for toxic phytoplankton blooms lyse cells and thus release huge amounts of toxins into the body of water. Because increasing phytoplankton blooms in water are a serious environmental problem worldwide, there is a need for new ways to prevent blooms from developing to a large scale. The preventative treatment of the present invention significantly reduces the amount of accumulated toxins and the concentrations of active agent required, and thus the cost and environmental hazard associated with the treatment.

Prior Art

[016] Various chemicals are used to attenuate/reduce/kill/inhibit cyanobacterial blooms in water bodies through oxidative stress. It is achieved either directly by the production of _{singlet oxygen, or more commonly by H2O2 ,} or by reagents that release _H2O2 , such as sodium percarbonate or salts of various metals such as copper, which cause oxidative stress (Gu et _al . , 2019). The use _{of H2O2 in} bloom treatments is based on the fact that cyanobacteria _are relatively sensitive to _H2O2 compared to other phytoplankton species (Tichy and Vermaas, 1999) (Matthijs et al., 2012) (Weenink et al., 2015 ) (Lin et al., 2018) (Daniel et al., 2019). However, the minimum concentrations of H ₂ O ₂ required to kill cyanobacterial cells seriously affect populations of various fish, zooplankton, and phytoplankton species (other than cyanobacteria). Additionally, when H ₂ O ₂ was applied to treat cyanobacterial blooms in a natural pond, the cyanobacterial population began to recover after 6-7 weeks (Matthijs et al., 2012). For this reason, in many parts of the world it is not permitted to treat water bodies with H ₂ O ₂ or other active substances that cause oxidative stress in cyanobacteria.

[017] Several articles have shown that high concentrations of the active agent lead to only temporary elimination of microalgae.

i. Matthijs et al. (2012) investigated the effects of _H2O2 applications in Lake Koetshuis, the Netherlands, and Plexiglas _- enclosed sites filled with water from there. The lake was contaminated with the cyanobacterium Planktothrix agardhii, a known producer of microcystin toxins, at concentrations of up to 2-8*10 ⁵ cells/ml in the lake and 2*10 ⁶ cells/ml in Plexiglas containers. The latter were 110 cm in diameter and 150 cm in height (but only 120 cm immersed in water). Thus, the surface area of the container was approximately 9500 cm ² and the water volume was 1140 l. The lowest concentration _{of H2O2} sufficient to significantly reduce the population of Planktothrix agard (P. Agardhii) was 2.5 mg/l, which is equivalent to 2.85 g/ ^m2 . Already at this concentration of H ₂ O _2, the photosynthetic parameters and the number of cells in the zooplankton population were greatly reduced.

ii. The surface area of Lake Koetshuis is approximately 0.12 ^km2 . Matthijs and colleagues (2012) calculated that the total volume of the lake is approximately 240,000 ^m3 . In terms of _H2O2 concentration _{, they used 240 kg H2O2 for} the whole lake _, which is equivalent to 2 g/ ^m2 . In lake experiments, various groups of phytoplankton (green diatoms, cryptophytes and cyanobacteria) were severely affected by the treatment, and levels of toxic cyanobacteria increased rapidly after just 6-7 weeks.

iii. Based on their laboratory and field studies, Weenink and colleagues (Weenink et al., 2015) discussed “How much hydrogen peroxide ( _HP ) ( _H2O2 ) should be added to selectively suppress cyanobacteria and at what phytoplankton densities?” They recommend using a minimum of 2.3 mg⋅l ^-1 H ₂ O ₂ per treatment, and the higher the phytoplankton biomass, the more H ₂ O ₂ should be applied.

iv. In a mesocosm experiment, Lin and colleagues (Lin et al., 2018) examined the effects of a range of _H2O2 concentrations ( _2-12 mg/L) on a Microcystis population, several phytoplankton groups, and bacterioplankton communities. Water samples of 150 L were taken from Lake Dianchi, China, and placed in plastic containers. The diameter of the containers was 56 cm (not mentioned in the article, but kindly provided by the author, Professor Nanqin Gan). Thus, the surface area of the container was 2462 cm ² and the amount of H ₂ O ₂ added was equivalent to 1.22-7.31 g/m ² . Lin et al. (2018) indicates that the excess _of Microcystis was reduced when _H2O2 was added at doses of 4 mg/L (2.44 g/ ^m2 ) and higher. Microcystis cell density did not decrease when _H2O2 applied at 2 mg/L (ANOVA, P > 0.05). At 4 mg/L there was a large decrease in the population _of various other phytoplankton and bacteria.

[018] All of the above studies have one or more of the following shortcomings: ineffective treatment (cyanobacterial population is not eliminated), only temporary effect (cyanobacterial population quickly recovers), or dose is too high (above the maximum permissible limit for drinking water and/or negative impact on beneficial fauna in the ecosystem).

[019] Thus, there remains a need for methods and compositions that can effectively treat cyanobacteria, i.e. in treatments that can significantly and for a long time reduce the effectiveness of cyanobacteria in an environmentally friendly way, i.e. with minimal impact on other phytoplankton and bacteria, and using low doses of the active substance (“AI”).

The essence of the invention

[020] The invention described herein provides an effective cyanobacteria treatment that reduces the concentration of cyanobacteria over an extended period of time with substantially no adverse effects on other populations of phytoplankton and bacteria that are important to the ecosystem of the reservoir, when using low doses of AI, thereby causing minimal harm to health when used. Among other things, the effect is achieved due to the gradual and continuous/long-term release of sublethal concentrations of the active substance, which programs toxic cyanobacteria to cell death, with minimal impact on other beneficial species of algae.

[021] The composition and method described in the present invention preferably allows for the addition of only 0.33 kg of sodium percarbonate (or other additive) per 1000 m ² , which is equivalent to 0.11 g/m ² (i.e., at least 11 times less than the minimum effective amounts used in the above studies).

[022] In some aspects, the present invention provides compositions for reducing the growth of phytoplankton in bodies of water, comprising:

i. active substance (also called “AI” in the present invention) at a concentration of 80.0-99.5% (w/w),

ii. coating material in a concentration of 0.5-20% (w/w),

wherein the critical surface tension of said hydrophobic composition is 15-60 dynes/cm, and the relative density of the composition before immersion in water is above 1.0 g/cm ³ .

[023] In some aspects, the present invention provides compositions for reducing the growth of phytoplankton in bodies of water, essentially consisting of:

i. active substance (also called “AI” in the present invention) at a concentration of 80.0-99.5% (wt/wt),

ii. coating material in a concentration of 0.5-20% (wt./mass.),

wherein the critical surface tension of said composition is 15-60 dynes/cm, and the relative density of the composition before immersion in water is above 1.0 g/cm ³ .

In some embodiments, the composition is formulated such that the effective specific gravity decreases below 1 g/cm ³ 0.01 to 120 minutes after immersion in water, causing the composition to float to the surface of the water (FIG. 1).

[024] The present inventor has unexpectedly discovered that compositions containing DV suitably encapsulated with a hydrophobic coating can, despite having a specific gravity greater than that of water (>1.0 g/cm ³ ), float or at least float within 0.01-120 minutes after immersion in water, and remain floating even after mixing. Which is further illustrated in the examples section.

[025] The present inventor has unexpectedly discovered that when the specific gravity of a given hydrophobic coating material is less than 1.0 g/ml, and the used DV is more than 1.0 g/ml, the increase in the proportion of coating material in the encapsulated composition is slowed down or even suppressed ascent of material from the Far East. As an example (see FIG. 1), a composition of 95% (w/w) copper-based DV beads and 5% (w/w) coating material floated slower (had a longer float time) than a composition made 99% (w/w) from the same DV and 1% (w/w) from the coating material (Fig. 1). In addition, 75% (w/w) copper-based DV with 25% (w/w) coating material did not float and sank to the bottom of the reservoir. Which is further illustrated in the examples section.

[026] In some embodiments, the floating composition preferably provides a very high percentage of DV in the final product, requiring minimal product (ie, algaecide) input to achieve the optimal lethal concentration in the water. As a result, the composition described in the present invention reduces the required dose of AI for treatment, overall operating costs and time to treatment, and thus provides an excellent environmentally friendly treatment course with minimal environmental impact.

[027] In addition, it was found that the range of 15-60 dynes/cm of surface tension of the coating material is critical for achieving buoyancy, and that the less coating applied (w/w), the faster the flotation occurs and the greater the fraction of DV is located on the surface (Fig. 1).

[028] Preferably, the buoyancy achieved is replicated by encapsulating various DV compounds such as, but not limited to, calcium hypochlorite, sodium percarbonate, copper sulfate pentahydrate, aluminum sulfate and potassium permanganate.

[029] In addition, various coating materials provided similar useful and unexpected results as long as the critical surface tension of the coating material was in the range of 15-60 dynes/cm.

[030] Without wishing to be bound by any particular theory, the present inventors believe that the buoyancy of a single non-wettable powder on the surface of water is determined by the interaction of various forces: lift, curvature and gravity. In case of spherical particles, it can be expressed as Mg/2σLsin(Θ)<1.0, where "M" is the mass of the particle, "g" is the gravitational acceleration, "L" is the contact length, σ is the surface tension of water, Θ is the angle of contact of the floating body, and 1.0 is the relative density of water, measured in g/cm ³ . Hydrophobicity may play a major role by changing the water-particle interactions, and thus the angle of the floating body. When large hydrophobic particles, 5-1500 µm in size, are placed on the surface of water, they can bond (possibly due to strong hydrophobic attractions) and form a meniscus on the surface of the water. When water tension is disrupted (depending on various parameters such as, but not limited to, water purity, temperature, and others), the composition may sink to the bottom, but then float to the surface.

[031] Without wishing to be bound by any particular theory, the present inventors believe that the unexpected floating of a composition having a specific gravity greater than 1.0 g/ml may be due to the hydrophobic properties of the composition.

[032] As an additional advantage, the composition described in the present invention can be formulated to have buoyancy, allowing the composition to remain submerged below the surface of an aquatic system, but not sink to the bottom (also referred to as partial buoyancy in the present invention), e.g. at a depth of 0 m - 1.5 m, preferably between 0.2-1.0 m below the surface of the water system when applied. This may be particularly advantageous for pre-bloom treatments as most of the algae/cyanobacteria population is below the surface compared to the floating mats associated with algal blooms (Bertone (ibid); Kudela (ibid).

[033] In some embodiments, semi-floating compositions can be formulated for slow or sustained release of the active substance. As shown in the present invention, it has been advantageously found that long-term exposure of phytoplankton to an algaecide causes cell death, even when the highest concentration of algaecide in a body of water is below its known lethal concentrations. In addition, a sublethal concentration of one DV was found to kill cyanobacteria while having minimal effect on green algae and even allowing green algae to recover and displacing remaining toxic phytoplankton (see Fig. 18 below).

[034] In some aspects, the present invention also relates to methods for controlling the growth of phytoplankton in bodies of water by treating them preventively, i.e. before the appearance of a dense population, often called a “bloom,” and/or before the formation of algal mats on the surface of the reservoir.

[035] Preferably, the treatment described in the present invention, carried out before the development of algal or cyanobacterial blooms, minimizes the amount of toxins released into the water body by lysing cells. For example, treatment of a population of Microcystis species according to the present invention can release up to 0.01 μg/L microcystin-LR into a body of water, i.e. 100 times less than the WHO maximum standard (https://www.who.int/water_sanitation_health/water-quality/guidelines/chemicals/microcystin/en/). This is in sharp contrast to traditional treatments applied when blooms are already established and when microcystin-LR levels can exceed 45 µg/L (Sakai, Scientific World Journal DOI: 10.1155/2013/838176, 2013).

[036] In some embodiments, the method may include depositing granules in the photic zone of a body of water (the layer of water in a body of water that is exposed to at least 1% light intensity at the surface), which varies with season, geology, geography, and population density phytoplankton. According to some embodiments of the invention, the method includes introducing a semi-buoyant composition formulated such that it remains at a distance of 0.02-1.0 m from the surface of the water. This is particularly preferable for pre-bloom treatments where a large proportion of the algae/cyanobacteria population is typically present 0.05-1.0 m below the surface (Bertone (ibid); Kudela (ibid).

[037] According to some embodiments of the invention, a composition is provided for attenuating, inhibiting and/or eliminating the growth of phytoplankton in a body of water, containing or essentially consisting of an active ingredient in concentrations of 80.0-99.5% (w/w) of the composition and coating material at a concentration of 0.5-20% (w/w) of the composition; wherein the critical surface tension of said composition is 15-60 dynes/cm, and the relative density of the composition before immersion in water is above 1.0 g/cm ³ , and the relative density of the composition decreases below 1 g/cm ³ after 0, 5-60 minutes after immersion in water.

[038] In some embodiments, the composition contains or consists essentially of active ingredient at concentrations of 90.0-99.5% (w/w) of the composition and a coating material at concentrations of 0.5-10% (w/w) of the composition. mass) compositions.

[039] In some embodiments, the composition may include granules having a first concentration of coating material and granules having a second concentration of coating material. This may advantageously provide a prolonged duration of release of the active substance, since the active substance is first released from granules having a lower concentration of coating material and then from granules having a higher concentration of coating material.

[040] As a non-limiting example, the composition may include granules having 1% wt./mass. coating material (and 99% w/w active ingredient), and include granules having 3% w/w. coating material (and 97% w/w active ingredient), thereby prolonging the release of the active ingredient over time.

[041] In some embodiments, the composition may not contain an encapsulated floating agent.

[042] In some embodiments, the coating material comprises behenic acid; Octadecanoic acid 2,3-dihydroxypropyl ester; glyceryl distearate; hexadecanoic acid; octadecanoic acid; fatty acid; C8-18 and C18 unsaturated fatty acids; C16-18 and C18 unsaturated fatty acids; potassium salts of C8-18 and C18 unsaturated fatty acids; sodium salts of C8-18 and C18 unsaturated fatty acids; C8-18 and C18 unsaturated mono- and diglycerides; C14-18 mono- and diglycerides; coconut fatty acids, polymers with glycerin and phthalic anhydride, wax, paraffin, rosin, silicone derivative or derivative thereof, or any combination thereof.

[043] In some embodiments, the composition may have a melting point of 50-90°C. In some embodiments, the composition may have a pour point below 20°C.

[044] In some embodiments, the coating material has an acid value of 3-8 mg KOH per gram. This may advantageously ensure optimal adhesion between the shell (coating material) and the core (active substance).

[045] In some embodiments, the coating material includes a wax, paraffin, fatty acid, or any combination thereof.

[046] In some embodiments, the concentration of active ingredient is approximately 80-99.5%. In some embodiments, the concentration of active ingredient is approximately 95-99.5%.

[047] According to some embodiments of the invention, the concentration of the coating material contained is in the range of about 0.5-20%. According to some embodiments of the invention, the concentration of the coating material contained is in the range of about 0.5-5%. In some embodiments, the concentration of the coating material is less than 20% (w/w) of the composition. In some embodiments, the concentration of the coating material is less than 15% (w/w) of the composition. In some embodiments, the concentration of the coating material is less than 10% (w/w) of the composition. In some embodiments, the concentration of the coating material is less than 5% (w/w) of the composition.

[048] In some embodiments, the composition contains granules having different concentrations of coating material. For example, according to some embodiments of the invention, the composition contains a first portion of granules containing 0.5-2% wt./mass. coating material mixed with a second part of granules having 3-10% coating material. According to some embodiments of the invention, the composition further contains granules having 6.5%-20% wt./mass. covering material. Different concentrations of the coating material may preferentially provide sustained release of the algaecide when immersed in a body of water and thus promote prolonged exposure of the cyanobacteria to the algaecide (eg, H ₂ O ₂ ). Without wishing to be bound by any particular theory, the present inventors believe that prolonged exposure causes death, primarily programmed cell death, of cyanobacteria (rather than necrotic cell death), preferably after a single treatment with the composition, despite the use of low doses of algaecide. This is unlike the commonly used necrotic kill, which requires a much higher (at least 10-fold) concentration of DV.

[049] In some embodiments, when the encapsulated DV used is H ₂ O ₂ , the applied concentration may be in the range of 10 ^-7 -10 ^-12 ppm. depending on the density of the phytoplankton population and the depth of the reservoir. It should be understood that this concentration is significantly lower than that usually used in non-encapsulated compositions, namely 2-4 * 10 ^-6 ppm. (See e.g. Matthijs et al., 2012: Weenink et al., 2015; Lin et al., 2018).

[050] In some embodiments, the critical surface tension of the composition is in the range of 20-45 dynes/cm or 30-45 dynes/cm.

[051] In some embodiments, the active agent includes an oxygen releasing agent, a chlorine releasing agent, a bromine releasing agent, an iodine releasing agent, a peroxide compound, a copper releasing agent, a manganese releasing agent, an aluminum releasing agent, or any combination thereof.

[052] In some embodiments, the composition may be formulated such that the active ingredient is released into the aqueous system at water temperatures below 45°C within 24 hours of application.

[053] In some embodiments, the composition may be formulated as granules with a size in the range of 10-1500 microns, or in the range of 300-1500 microns, or in the range of 1-10 mm.

[054] In some embodiments, the composition is configured to remain submerged to a depth of about 0.02-1 m below the surface of the aquatic system after application and/or after or during ascent/re-buoyancy (see examples below).

[055] According to some embodiments of the invention, there is provided a method of preventing and/or inhibiting the development of toxic phytoplankton blooms in a body of water, including identifying areas in the body of water with a toxic phytoplankton biomass above 8000 cells/ml or a chlorophyll a concentration above 3 μg/L and introducing a floating algaecide composition per area of the reservoir, so that the concentration of algaecide in the area is below the lowest lethal dose.

[056] In some embodiments, application can effectively prevent algal or cyanobacterial blooms when applied before the bloom develops. In some embodiments, the method can substantially eliminate algal or cyanobacterial infestations when applied after algal or cyanobacterial foam has appeared.

[057] In some embodiments, application occurs when the chlorophyll a concentration measured anywhere in the body of water is greater than 3 μg/L. In some embodiments, application occurs when the chlorophyll a concentration measured anywhere in the body of water is above 3 μg/L and below 10 μg/L.

[058] In some embodiments, a body of water includes a reservoir, ocean, lake, dam, pond, estuary, bay, sea, or river.

[059] In some embodiments, the method further includes applying a second dose of the floating algaecide composition to the site 0.5 to 10 hours after its first application.

[060] In some embodiments, the algaecide composition is configured to release the algaecide within at least 2 hours after application.

[061] In some embodiments, the composition is formulated to remain submerged to a depth of about 0.02 to 1 m below the surface of a body of water.

[062] In some embodiments, the body of water is a body of water that has previously experienced toxic phytoplankton blooms. Thus, one skilled in the art will appreciate that while the composition and method of use thereof are suitable for use in water bodies with the first occurrence, it has surprisingly been discovered that even water bodies subject to repeated occurrences of toxic phytoplankton blooms can be successfully treated using those described in the present invention of the method and/or composition.

[063] In some embodiments, the administered composition contains 80.0-99.5% (w/w) active ingredient and 0.5-20% (w/w) coating material, as substantially described in the present invention.

[064] In some embodiments, the applied composition comprises granules having different concentrations of coating material. For example, according to some embodiments of the invention, the composition contains a first portion of granules containing 0.5-2% wt./mass. coating material, and a second part of granules having 3-10% coating material. According to some embodiments of the invention, the composition further contains granules having 10%-20% wt./mass. covering material. This may advantageously provide prolonged release of the algaecide and thus prolonged exposure of the cyanobacteria to a low concentration of algaecide (eg, H ₂ O ₂ ).

[065] In some embodiments, the coating material has a melting point greater than 45°C, greater than 50°C, or greater than 55°C. Each possibility is a separate embodiment of the invention.

[066] In some embodiments, the coating material has a pour point below 20°C, below 30°C, or below 40°C. Each possibility is a separate embodiment of the invention.

[067] According to some embodiments, the critical surface tension of the composition is 15-60 dynes/cm, and the relative density of the composition before immersion in water is greater than 1.0 g/cm ³ .

[068] In some embodiments, the granule size is in the range of 0.3-15 mm, 0.3-1 mm, or 1-10 mm. Each possibility is a separate embodiment of the invention.

[069] In some embodiments, the composition/granules have a viscosity of 6-8 cP at 70°C.

[070] According to some embodiments of the invention, there is provided a method for treating, inhibiting and/or eliminating the growth of phytoplankton in bodies of water, comprising:

i. testing for the presence and density of phytoplankton (for example, for certain phytoplankton pigments),

ii. determination of the contaminated area by coordinates,

iii. applying the floating composition locally, upwind with the wind from behind, opposite the infested area, so that the wind pushes the floating particles of the algaecide composition towards and/or with the infested area,

thereby treating, inhibiting and/or eliminating the development of phytoplastic blooms.

[071] In some embodiments, the treatment may be preventative, allowing treatment with a minute dose of DV. In the present invention, the terms "preventive treatment" and "preventive treatment" can be used interchangeably and can refer to treatments carried out during the early stages of phytoplankton contamination.

[072] In some embodiments, the composition can be applied by emptying containers containing the composition at one or more “drop zones.” In some embodiments, the composition can be applied to discharge zones without the need for mixing, shaking, spraying, or otherwise distributing the composition over the surface of the aqueous system. In some embodiments, one or more release zones may be located on the shore of a body of water, thereby preferably eliminating the need for boats or other delivery equipment, as substantially illustrated in FIG. 8A and FIG. 8B in the present invention.

[073] In some embodiments, the composition can be applied using a “sprayer” similar to those used to spread salt pesticides or agricultural crops. Spraying can be particularly useful when treating large water systems. The compound can be applied from any type of boat without any volume restrictions in strategic “dump” zones, from where the compound can be distributed by currents and aggregated with algae clusters.

[074] Large quantities of the composition can be manufactured and packaged in silos of varying sizes (eg, 10 tons). Optionally, the entire silage can be transported directly to the desired “drop zone” where it can be disposed. In some embodiments, a distributor may be incorporated into such a silo to better control the amount and flow of product used in each "drop zone."

[075] In some embodiments, the preventive treatment of phytoplankton may include the application of at least two different photosynthetic microbial inhibitors, for example, alternately between treatments. As a non-limiting example, two sequential treatments with H ₂ O ₂ -based compositions may be performed followed by a third treatment with a copper-based composition.

[076] In some embodiments, a combination of two photosynthetic microbial inhibitors can be applied in one treatment, for example, copper and H ₂ O ₂ based compositions can be applied simultaneously.

[077] In some embodiments, the combined or alternating action of more than one photosynthetic microbial inhibitor can (a) prevent the accumulation of resistant strains and (b) affect different phytoplankton species with different sensitivities, and (c) reduce the total amount of photosynthetic microbial inhibitor applied . Each possibility is a separate embodiment of the invention.

[078] In some embodiments, the inspection may be remote, such as by buoys, from the air, or from space.

[079] In some embodiments, preventative treatment of phytoplankton (early season) allows approximately 2 times, 3 times, 5 times, 10 times, 15 times, 20 times, 50 times less DV, or any value in between, to be used per season compared with a late bloom treatment (also referred to in the present invention as a “response treatment” or “end of season treatment”). Each possibility is a separate embodiment of the invention.

[080] According to some embodiments, if 0.33 kg of active ingredient, such as sodium percarbonate, is added per 1000 m ² , this is equivalent to 0.325 g/m ² (molecular weight of sodium percarbonate 2Na ₂ CO ₃ *3H ₂ O ₂ equal to 314 g, 3 molecules of H ₂ O ₂ are released, i.e. 102 g of H ₂ O ₂ ). Accordingly, 1 kg of sodium percarbonate releases 325 g of H ₂ O ₂ . This corresponds to 0.11 g/ ^m2 , which is 11 times less than the minimum amounts used in various studies.

[081] In some embodiments, preemptive treatment of phytoplankton completely prevents the development of a full-blown bloom.

[082] In some embodiments, the phytoplankton preventive treatment provides at least 40% or at least 60% reduction in phytoplankton biomass after 24 hours. In some embodiments, the phytoplankton preventative treatment provides at least 80% or at least 90% reduction in phytoplankton biomass after 48 hours.

[083] In some embodiments, the treatment will change the ratio between cyanobacteria and non-toxic algae by 1.5 times, 4 times, 10 times or more within 24-72 hours of the start of treatment (compared to the ratio before treatment). Each possibility is a separate embodiment of the invention. In some embodiments, the ratio can be determined by measuring photosynthetic pigments (which absorb light energy required for photosynthesis) as representative of certain phytoplankton species, such as: chlorophyll a, chlorophyll b, chlorophyll c1, chlorophyll c2, fucoxanthin, peridinin, phycocyanin, and /or phycoerythrin. Additionally or alternatively, the ratio can be determined spectroscopically by measuring the fluorescence emitted by photosynthetic pigments, or using phytoplankton cell counting (microscopy, cell sorting), or thermal imaging. Each possibility is a separate embodiment of the invention. Without wishing to be bound by any particular theory, the present inventors believe that the treatment methodology and sustained release composition described herein alters the ecological balance of a body of water such that cyanobacteria are lysed or otherwise killed, whereupon non-toxic algae are which are minimally affected by a sublethal dose of DV) gain an advantage and reproduce in large numbers. This "self-healing" mechanism of the pond maintains the treatment and prolongs the results as the non-toxic algae further competes with the cyanobacteria to keep their numbers low.

[084] In some embodiments, preventive treatment of phytoplankton eliminates or at least significantly reduces the concentration of toxin-producing cyanobacteria or algae in the aquatic system.

[085] In some embodiments, preventative treatment of phytoplankton eliminates the need to chlorinate drinking water supplies.

[086] In some embodiments, preventive treatment of phytoplankton eliminates odor and taste in an aquatic system, which may be particularly advantageous for recreational and aquaculture purposes.

[087] In some embodiments, the phytoplankton preventative treatment further reduces the population of small planktonic crustaceans (e.g., Daphnia species or 0.2-5 millimeter long copepod species) that feed on the phytoplankton (e.g., by at least 10% by at least by 50% or at least 90% within 1, 7 and 30 days respectively). These organisms, which feed on phytoplankton blooms, increase the incidence of clogged pipes. In some embodiments, a reduced crustacean population reduces the need to apply highly toxic pesticides (eg, abamectin) that are typically used to inhibit, reduce, or kill the growth of planktonic crustaceans. Advantageously, preventative treatment of phytoplankton can thus reduce wear and tear of filters and pumps.

[088] In some embodiments, preventative treatment of phytoplankton further reduces or prevents the occurrence of enterobacteriaceae species.

[089] Advantageously, due to the above benefits of preventive treatment of phytoplankton, the present invention reduces overall seasonal operating costs by as much as 90%, thereby making treatment of large bodies of water (>10 km ² ) technically, environmentally and financially feasible.

[090] In some embodiments, the method further includes conducting a follow-up test to determine whether additional processing is necessary. Each possibility is a separate embodiment of the invention. Specific embodiments of the present invention may include some, all, or none of the above advantages. One or more technical advantages may be readily apparent to those skilled in the art from the figures, descriptions and claims included herein. In addition, although certain advantages are listed above, various embodiments of the invention may include all, some, or none of the listed advantages.

[091] According to some embodiments of the invention, there is provided a method of preventing and/or eliminating the development of phytoplankton blooms in bodies of water larger than 5000 m ² including applying a floating algaecide composition to approximately 0.001-20% of the surface at a predetermined location that allows wind to passively disperse the composition.

[092] In some embodiments, the method further includes the initial step of checking for the development of a phytoplankton bloom, wherein the check includes determining phytoplankton biomass and/or concentration. In some embodiments, application of the composition includes applying the composition preemptively prior to the formation of a visible/detectable phytoplankton bloom and/or foam. As used herein, the term "visible" may refer to blooms/scum floating on the surface of a body of water visible to the naked eye, or to blooms detected by laboratory analysis.

[093] In some embodiments, the method includes introducing a floating composition into a predetermined "drop zone" on the windward side of a contaminated portion of a body of water such that wind and current cause the composition to drift toward and/or with a phytoplankton bloom; thereby reducing, inhibiting, preventing and/or eliminating the development of phytoplankton blooms.

[094] In some embodiments, applying the composition includes applying the composition when the phytoplankton biomass in the "drop zone" is below 10 μg/L chlorophyll a or above 20,000 cells/mL or less.

[095] In some embodiments, the composition is added such that the algaecide concentration in the aqueous system/body is in the range of 10 ^-7 -10 ^-12 ppm. on average, depending on the depth, within 24 hours after its application throughout essentially the entire volume of the reservoir (for example, at least 85%, at least 90%, or at least 95% of the reservoir). According to some embodiments of the invention, the composition is applied so that the algaecide content in the reservoir is below 10 ^-9 ppm. on average over the entire volume of the reservoir within 72 hours, within 48 hours or within 24 hours. In some embodiments, the preventative treatment described herein can be performed prior to algal or cyanobacterial blooms and thus ensure that the amount of toxins measured in the aquatic system is below 0.1 µg/L (10% of the WHO maximum level).

[096] In some embodiments, application of the composition includes application of the composition to approximately 0.001-25% of the surface of the body of water. In some embodiments, application of the composition includes application of the composition to approximately 0.001-15% of the surface of the body of water. In some embodiments, application of the composition includes application of the composition to approximately 0.001-10% of the surface of the body of water.

[097] In some embodiments, the body of water is a reservoir, ocean, lake, dam, pond, estuary, bay, sea, or river. In some embodiments, the body of water has a size of at least 10,000 m ² . In some embodiments, the water system is at least 1 km ² or 10 km ² or 100 km ² in size.

[098] In some embodiments, the composition is formulated to remain submerged in the photic zone of a body of water. In some embodiment, the photic zone has a depth of about 0.1-1 m below the surface of the reservoir, about 0.02-1.5 m below the surface of the reservoir, about 0.1-2 m below the surface of the reservoir, or about 0.1- 5 m below the surface of the reservoir.

[099] As used herein, the term “photic zone” refers to the layer of water in a body of water that is exposed to sunlight. In some embodiments, the photic zone depth may be up to 1 meter, up to 10 meters, or up to 100 meters. The depth of the photic zone depends on the density of the phytoplankton population. For example, it can range from 0.1 m during a massive algal bloom to 100 m when the phytoplankton population is less than 10,000 cells/ml. The depth of a body of water's photic zone can further vary depending on the time of day, season, geology, or geography of the body of water.

[0100] In some embodiments, the composition is configured to release the algaecide within at least 0.5 hour, at least 1 hour, at least 2 hours, or at least 6 hours after application. Each possibility is a separate embodiment of the invention.

[0101] In some embodiments, the composition is applied prior to an algal or cyanobacterial bloom so that the amount of toxin measured in the body of water, including the area near the application site, within 72 hours, within 48 hours, or within 24 hours after application is less 1 µg/l.

[0102] In some embodiments, the composition is formulated to remain submerged to a depth of about 0.02 to 2 m below the surface of a body of water.

[0103] According to some embodiments of the invention, the composition contains 80-99.5% wt./mass. algaecide, 0.5-20% w/w covering material. In some embodiment, the rate of release of the active ingredient (AI) from the floating algaecide composition can be controlled by changing the relative proportions of the active ingredient (AI) and the coating material. The smaller the fraction of the coating material, the faster the DV is released.

[0104] According to some embodiment of the invention, the duration of treatment of phytoplankton with DV is determined by the rate of release of DV from the floating algaecide composition. The slower the release, the longer the phytoplankton are exposed to DV.

[0105] According to some embodiment of the invention, the longer the phytoplankton is exposed to the active substance (AD), the greater the fraction of phytoplankton cell death.

[0106] It should be understood that the number of subsequent treatments, as well as the frequency of treatments (time between subsequent treatments) can be determined in accordance with the rate of release of the DV.

[0107] In some embodiments, the composition is added such that the average algaecide concentration in the aqueous system is reduced to 10 ^-9 -10 ^-15 ppm. within 24 hours throughout substantially the entire volume of the reservoir (eg, at least 85%, at least 90%, or at least 95%).

[0108] In some embodiments, application of the composition includes application of the composition to approximately 0.001-25% of the surface of the body of water. In some embodiments, application of the composition includes application of the composition to approximately 0.001-15% of the surface of the body of water. In some embodiments, application of the composition includes application of the composition to approximately 0.001-10% of the surface of the body of water.

[0109] In some embodiments, the slow release of the active material in the photic zone exposes the toxic cyanobacteria to AD for a period of time sufficient to trigger mass cell death.

[0110] Another advantage of the coated composition is that it is much less corrosive to the aircraft that deliver or distribute it or distribute it throughout the body of water being treated.

[0111] Specific embodiments of the present invention may include some, all, or none of the above advantages. One or more technical advantages may be readily apparent to those skilled in the art from the figures, descriptions and claims included herein. In addition, although certain advantages are listed above, various embodiments of the invention may include all, some, or none of the listed advantages.

[0112] In addition to the illustrative aspects and embodiments of the invention described above, additional aspects and embodiments of the invention will become apparent with reference to the figures and upon examination of the following detailed descriptions.

Brief description of drawings

[0113] The invention will now be described in terms of specific examples and embodiments of the invention with reference to the following illustrative figures so that it may be more fully understood.

[0114] In FIG. 1A - fig. 1C shows photographs of a time series of 10 mL tubes containing 5 grams of copper sulfate granules coated with 0, 0.5, 1, 2.5, or 5% (w/w) coating material. The untreated copper salt ("0% coverage") sank to the bottom immediately after dispersion. On the contrary, the coated copper composition sank to the bottom and floated up within a short time. (A) photograph of the water surface 2 hours after dispersing copper-based DV compositions containing (from left corner) 0%, 0.5%, 1%, 2.5% and 5% (w/w) coating material ; (B) time series images of tubes from 5 minutes to 24 hours, as noted; (C) Example from (B) granule residue at the bottom of the tubes after 5 minutes, 30 minutes, 2 hours, and 5 hours.

[0115] In FIG. 2 schematically illustrates an experimental setup for studying the buoyancy of the compositions described in the present invention, including (1) a balance; (2) measuring block with hole; (3) a hook at the bottom for measuring weight; (4) a glass filled with water, simulating a water system; (5) the scales.

[0116] In FIG. 3A - fig. 3H shows an example photograph of a time series of sodium dichloroisocyanurate (SDC) coated (97% (w/w) DV and 3% (w/w) coating) floating, or during ascent. Note the arrows indicating specific patterns.

[0117] In FIG. 4 shows example photographs of glasses filled with water and the composition detailed in Table 1, with increasing coating percentages (50%, 15% and 2.5% (w/w) from left to right). Images were taken 30 minutes after 25 grams of each composition were placed in water.

[0118] In FIG. 5A - fig. Figure 5B shows example photographs of sodium percarbonate placed in 15 ml tubes containing 5 grams of uncoated DV (left) and 5 grams of coated DV (right), at time 0 (FIG. 5A). After vigorous mixing (Fig. 5B), the entire coated composition settled and immediately began to float.

[0119] In FIG. Figure 6 shows two ten-liter cylinders filled with water with added sediment after one hour of treatment with the same dose of copper sulfate pentahydrate. The left cylinder was treated with copper sulfate pentahydrate granules (simulating standard treatment), which immediately settled into the deposits. The right cylinder was treated with a coated copper based buoyant compound containing 2.5% buoyant, which floated on the water and released its contents into the water column (from top to bottom).

[0120] In FIG. Figure 7 shows a graph comparing three approaches over one year on 50-hectare ponds: (1) no treatment: solid black line indicates natural progression of cyanobacterial bloom infestation; (2) according to the late-stage operational treatment: the solid gray line indicates the sharp drop in flowering levels after each 50 kg/ha treatment, for a total of 1.75 tons in one year; (3) preventative treatment: dotted black line and arrows indicating eight successive 5 kg/ha treatments, totaling 200 kg, ~90% reduction in total dose.

[0121] In FIG. 8A and FIG. 8B shows photographs of a section of the bank where two people apply 500 kg of product in a very short time. The compound was added to the water in large piles of ~5-10 kg each (Fig. 8A). Quite soon, within 10-30 minutes, the granules began to float (as indicated by the arrows) and moved with the wind in the direction of the algal foam (Fig. 8B). The total time it took for the heaps to dissipate by themselves was 24-36 hours.

[0122] In FIG. Figure 9 shows the concentrations of algaecide in different areas of the irrigation pond after application locally, opposite the target area. The top "Day 1" figure details measurements that were taken 0-3 hours after treatment. The bottom "Day 2" figure details measurements that were taken 24 hours after treatment. Note the dramatic change in chlorophyll a concentrations over the course of 24 hours, and the minimal concentrations of DS in the water during the first 24 hours of treatment.

[0123] In FIG. 10 shows photographs of a 75,000 m ² irrigation pond in the Negev Desert that was infested with Microcystis species and treated with 150 kg of copper-based float, (A) before and (B) after treatment.

[0124] In FIG. Figure 11 shows a US National Oceanic and Atmospheric Administration (NOAA) satellite image showing high levels of cyanobacteria present in Lake Chippewa, Ohio, shortly before processing (yellow and red pixels from August 3, top panel), which were completely cleared immediately after processing (August 11 onwards, black pixels, bottom panels). Gray pixels represent clouds.

[0125] In FIG. Figure 12 shows high-quality images obtained using a microscope. A) Pre-treatment, most of the phytoplankton observed under the microscope belonged to cyanobacteria species, mainly Planktothrix species and Anabaena species. C) Three days after treatment, no toxin-producing cyanobacteria were detected. The phytoplankton captured in the microscope image were mostly beneficial green algae, mainly Diatom and Chlamydomonas-like species. Several species of Spirulina, a non-toxic cyanobacterium, have also been recorded.

[0126] In FIG. 13 shows relative measurements of dissolved oxygen (DO); the ratio of the total biomass of eukaryotic algae to the biomass of cyanobacteria - “resistance index” (algae to cyano); clogging potential indicator; and pH. Measurements were carried out daily, at 8 o'clock in the morning, for 9 days in a row and at different points of the lake. Measurements of DO, algae to cyano, and clogging indicator were normalized to day 0.

[0127] FIG. 14 is an image of Lake Chippewa, Ohio, showing the formation of protein foam throughout the lake on day 3 after treatment.

[0128] In FIG. Figure 15 shows microcystin levels measured in Chippewa Lake after the Medina County Park District initiated weekly cyanotoxin measurements in 2016. The lake freezes from December to March. The red dotted arrow indicates the start of treatment with the composition described in the present invention.

[0129] In FIG. 16 shows the result of a seasonal treatment of the compositions described herein in the Kibbutz Nitzanim irrigation reservoir, indicating the strong impact of the treatment on algae levels, its prolonged effect, as well as its ability to influence species diversity in favor of non-toxic species (1 kg/ha ≈ 1 lb/ acre).

[0130] In FIG. Figure 17 shows the amount of copper used as an algaecide in the Kibbutz Nitzanim irrigation reservoir during 2014-2018.

[0131] In FIG. Figure 18 shows visible changes in water quality in a pond near Lake Taihu, China, treated with sodium percarbonate (Lake Guard™ Ohu). The top panel shows the pond, pre-treatment. The bottom panel shows a pond 12 weeks after treatment.

[0132] In FIG. Figure 19 shows the changes in chlorophyll (A) and phycocyanin (B) after treatment.

[0133] In FIG. Figure 20 shows the changes in pH (A) and dissolved oxygen (B) after treatment.

Detailed Description of the Invention

[0134] The following description will present various aspects of the invention. For purposes of explanation, specific forms and details are set forth to provide a thorough understanding of the various aspects of the invention. However, it will also be apparent to one skilled in the art that the invention can be practiced without the specific details provided in the present invention. In addition, well-known features may be omitted or simplified so as not to obscure the invention.

Definitions

[0135] As used herein, the term “phytoplankton” refers to microorganisms that carry out photosynthesis in an aquatic environment. The two main groups of phytoplankton are: (1) cyanobacteria (also called "blue-green algae") and (2) microalgae (i.e. eukaryotic photosynthetic microorganisms).

[0136] Non-limiting examples of cyanobacteria species include: Microcystis spp., Nodularia spp., Cylindrospermopsis spp., Lyngbya spp., Planktothrix spp., Oscillatoria spp., Schizothrix spp. , Anabaena species, Pseudanabaena species, Aphanizomenori species, Umezakia species, Nostoc species, Spirulina species. Their known cyanotoxins include: microcystins, nodularins, anatoxin, cylindrospermopsins, lingbiatoxin, saxitoxin and lipopolysaccharides.

[0137] Non-limiting examples of algae include: Karenia spp., Gymnodinium spp., dinoflagellates, Prymnesium spp. (also called golden algae). Their list of toxins includes paralytic shellfish poisoning (PSP), neurotoxic shellfish poisoning (NOM), aplysiatoxins, beta-N-methylamine-L-alanine (BMAA), brevetoxin, and ptychodiscus.

[0138] As used herein, the term “non-toxic algae” refers to algae that do not produce toxins of any kind or concentration harmful to the ecosystem of an aquatic system. In some embodiments, the nontoxic algae do not produce paralytic shellfish poisoning (PSB), neurotoxic shellfish poisoning (NOM), aplysiatoxins, BMAA, brevetoxin, and ptychodiscus.

[0139] As used herein, the term “non-toxic cyanobacteria” refers to cyanobacteria that do not produce toxins of any kind or concentration harmful to the ecosystem of an aquatic system. In some embodiments, the nontoxic cyanobacteria do not produce microcystins, nodularins, anatoxin, cylindrospermopsins, lingbiatoxin, saxitoxin, and lipopolysaccharides.

[0140] As used herein, the term “phytoplankton blooms” refers to a population explosion of phytoplankton in bodies of water. The phenomenon is established when large numbers of buoyant photosynthetic microorganisms float at photic depth (where the light intensity is higher than 1% than at the surface of the water) or on the surface of the water. The term refers to the phenomenon where a species of cyanobacteria or microalgae increases its biomass by a logarithmic rate over the course of a day, a week, a fortnight, a month, a season.

[0141] As used herein, the term “algaecides” refers to compounds capable of destroying, lysing, killing, inhibiting growth, inhibiting proliferation, inhibiting photosynthesis, or otherwise reducing/preventing/inhibiting/treating phytoplankton infestation. Non-limiting examples of suitable algaecides include oxidizing agents (eg, hypochlorite, H ₂ O ₂ or H ₂ O ₂ producing chemicals such as sodium percarbonate), phosphate chelating agents (eg, aluminum sulfate salts, bentonite clay), compounds based on copper, potassium permanganate and combinations thereof. In some embodiments, the algaecide may include a combination of algaecides, such as, but not limited to, H ₂ O ₂ and copper-based algaecides, the combination of which may have a synergistic effect, thereby reducing overall chemical use. As used herein, the term "least lethal dose" refers to the smallest amount of drug that can kill phytoplankton when exposed to an algaecide for less than 24 hours.

[0142] Without wishing to be bound by any particular theory, the present inventors believe that, in addition to the influence of abiotic parameters, the sensitivity of cyanobacteria to H ₂ O ₂ depends on the specific conditions in each body of water, such as the composition of phytoplankton and its ability to degrade H ₂ O ₂ (Weenink et al., 2015, Combatting cyanobacteria with hydrogen peroxide: a laboratory study on the consequences for phytoplankton community and diversity. Front Microbiol 6: doi:10.3389/fmicb.2015.00714). Consequently, when preparing for treatment, a threshold concentration is determined above which the active substance (for example, H ₂ O ₂ ) kills phytoplankton/cyanobacteria when applied as a single dose.

[0143] In some embodiments, the lethal dose may be determined as follows:

1. Collect cells, for example using a phytoplankton net.

2. Collect cells (eg by flushing the net with a small volume of distilled water, such as 100 ml (exact volume depends on cell density)).

3. Place the sample into tubes (eg 1 ml) and centrifuge the tubes.

4. Add a range of H ₂ O ₂ concentrations using the stock solution (eg 0, 0.5, 1, 2, 4 and 10 mg/L).

5. Whirlwind and wait 30-60 minutes.

6. Spin the tubes and measure the absorbance at wavelengths 620, 680 and 730 nm. This allows us to estimate the amount of pigments released by dying cells.

[0144] As used herein, the term "body of water" refers to any type of reservoir, aquaculture, basin, marine or fresh or salt water, ocean, bay, sea, standing water or river.

[0145] As used herein, the term "water system" can refer to any body of water, either natural or man-made.

[0146] As used herein, the terms “active ingredient (AI),” “base material,” “raw material,” and “technical compound” refer to any reactive compound that is determined to exhibit reactivity against microorganisms in an aqueous system. Non-limiting examples of AIs include detergents, antibiotics, and antiphotosynthetic algaecides. In some embodiments, the AD may be any phytoplankton or zooplankton inhibitory agent.

[0147] In some embodiments, the term "attenuation" as used herein refers to a reduction in phytoplankton biomass by 90%, 80%, 70%, 60%, 50%, or more over a period of 30 minutes, 90 minutes, 6 hours , 1 day, 2 days or one week from application treatment. Each possibility is a separate embodiment of the invention.

[0148] In the present invention, the terms "necrosis" and "necrotic cell death" can be used interchangeably and refer to a form of cell damage that leads to premature cell death due to, for example, high levels of poison or toxins that impair cell function/structure.

[0149] As used herein, the term “programmed cell death (PCD)” refers to cell death caused by internal or external signal(s) mediated by an intracellular genetically regulated program.

[0150] In some embodiments, the term "season" as used in the present invention refers to the period of time extending between the onset of logarithmic growth of phytoplankton (defined by either cell density levels that increase more than 2 times during a period of time: one day, week, fortnight or month; either when cell density exceeds 8 μg chlorophyll a/L or 8000 phytoplankton cells/ml) and the end of logarithmic growth (when cell density levels change little or even naturally fall below 10 μg chlorophyll a/L) or 20,000 phytoplankton cells/ml). It should be noted that in some cases, in some places, based on the above criteria, a "season" may not be an annual occurrence, but rather something that occurs throughout the year.

[0151] As used herein, the term "batch treatment" refers to treatment every 24 hours, 2 days, weekly, every 2-4 weeks, once a month, once a year, or twice a year. Each possibility is a separate embodiment of the invention. In some embodiments, the batch treatment may be a seasonal treatment.

[0152] As used herein, the term “contaminated site” refers to a site that is contaminated with phytoplankton biomass at a cell density that is about or greater than a concentration of 10 μg/L chlorophyll a or greater than 20,000 phytoplankton cells/mL. A site can be identified using sensors or standard laboratory extraction methods to detect photosynthetic pigments (which absorb light energy needed for photosynthesis) as representative of certain phytoplankton species, such as: chlorophyll a, chlorophyll b, chlorophyll c1, chlorophyll c2, fucoxanthin, peridinin , phycocyanin, phycoerythrin. Detection can also be accomplished spectroscopically, by fluorescence emitted by photosynthetic pigments, or using phytoplankton cell counting (microscopy, cell sorting), or thermal imaging. Identifying and mapping the contaminated area can be done using unmanned aerial vehicles or satellite surveillance through multispectral imaging. This can also be done using a sensor connected to a boat that crosses a body of water to effectively monitor the surface of the water.

[0153] As used in the present invention, the term "critical surface tension" refers to the surface tension of solids, powders, etc. It can be measured as the surface tension of liquids (or liquid mixtures), which causes the liquid to completely spread over a solid surface. The critical surface tension value is measured in dynes/cm. It can be determined by the matrix of liquids mixed together to change the surface tension resistance of water, which is also supported by an example (Ghahremani et al., Der Chemica Sinica 2: 212-221, 2011). Different materials have different surface tension values, for example paraffins ~ 23-24 dynes/cm, Teflon ~ 19-21 dynes/cm, polyvinyl chloride ~ 45 dynes/cm, etc.

[0154] In the present invention, the terms "floating composition" and "floating composition" can be used interchangeably and refer to compositions formulated to float on the surface and/or to remain submerged in the water column without settling to the bottom of the aquatic system. According to some embodiments of the invention, the floating/buoyant composition can be substantially uniformly distributed throughout the water column. In some embodiments, the floating composition may be formulated to reach a certain depth (above ground) in the water column (e.g., 0.01-5 cm below the surface, or 10-200 cm below the surface, or 20-100 cm below the surface ).

[0155] As used herein, the term “acid number” refers to the mass of KOH in mg required to neutralize 1 gram of fatty acid, eg one gram of coating material.

[0156] As used herein, the term "substantially consisting of" in relation to the compositions described herein refers to compositions comprising less than 2% w/w, less than 1% w/w, less than 0.5% w/w ./wt., less than 0.1% wt./wt., less than 0.05% wt./wt. or less than 0.01% w/w components other than those described. Each possibility is a separate embodiment of the invention.

[0157] The terminology used in the present invention is provided solely for the purpose of describing specific embodiments of the invention and is not intended to be limiting. As used herein, the singular forms do not exclude the possibility of plural forms unless the context clearly indicates otherwise. In addition, it is understood that the terms “comprises” or “comprising” as used herein establish the presence of specified features, steps, actions, but do not eliminate or exclude the presence or addition of one or more other features, steps, actions, or their groups. In some embodiments, the term “comprising” may be replaced by the term “essentially consisting of” or “consisting of.”

[0158] The terms “about” and “approximately” refer to a reasonable deviation from a predetermined amount that retains the ability to achieve one or more functional effects to substantially the same extent as the predetermined amount. Also in the present invention, the term may refer to a value of plus or minus 10% of a set value; or plus or minus 5%, or plus or minus 1%, or plus or minus 0.5%, or plus or minus 0.1%, or any percentage in between.

Compositions

In some aspects, the present invention provides compositions for attenuating, treating, inhibiting, reducing and/or eliminating phytoplankton growth in bodies of water, comprising:

i. active substance in a concentration of 80.0-99.5% (wt./mass.),

ii. coating material in a concentration of 0.5-20% (w/w),

in this case, the critical surface tension of the composition is 15-60 dynes/cm, and the relative density of the composition before immersion in water is above 1.0 g/cm ³ .

[0159] In some embodiments, the composition is formulated such that the relative density decreases below 1.0 g/cm ³ within 0.1-60 minutes, 0.25-60 minutes, 5-60 minutes, or 10-60 minutes after immersion in water. Each possibility is a separate embodiment of the invention.

[0160] According to some embodiments of the invention, the composition consists of an active ingredient and a coating material, i.e. contains essentially exclusively the listed components (active ingredient and coating) and less than 40%, less than 20%, less than 10%, less than 5%, 1% or 0.1% of other components (impurities or inert materials). Each possibility is a separate embodiment of the invention.

[0161] In some embodiments, the critical surface tension of the composition is 20-45 dynes/cm, or particularly 28-32 dynes/cm. Each embodiment is a separate embodiment of the invention. In some embodiments, the critical surface tension of the composition is about 30 dynes/cm. In some embodiments, the critical surface tension of the composition is approximately 35 dynes/cm.

[0162] In some embodiments, the concentration of the active substance is 75-99.5%, in particular 80-99%, or in particular 95-99%, each option being a separate embodiment of the invention. In some embodiments, the active ingredient is an inhibitor of photosynthetic microorganisms. In other embodiments, any active ingredient required to formulate a buoyant composition may be formulated according to the present invention.

[0163] In some embodiments, the active ingredient may include any active ingredient, including any type of water disinfectant, capable of treating, inhibiting and/or eliminating, reducing the growth of aquatic pests such as phytoplankton blooms.

[0164] Non-limiting examples of suitable active ingredients include oxygen releasing agents, chlorine releasing agents, bromine releasing agents, iodine releasing agents, peroxide-based compounds, copper releasing agents, manganese releasing agents, aluminum releasing agents, photosynthesis inhibitors, and any combination thereof.

[0165] In particular, the active agent may be or include sodium percarbonate, copper sulfate pentahydrate, calcium hypochlorite, sodium dichloroisocyanurate, aluminum sulfate containing salts, titanium dioxide, phthalimido-peroxy-hexanoic acid, quaternary ammonium compounds, sodium hypochlorite, chlorine , bronopol, glutaral, alkyl*-dimethylbenzylammonium chloride *(50%С14, 40%С12, 10%С16), alkyl*-dimethylbenzylammonium chloride *(60%С14, 30%С16, 5%С18, 5% С12), 1-(alkyl*-amino)-3-aminopropane monoacetate *(47%С12, 18%С14, 10%С18, 9%С10, 8%С16, 8%С8), trichloro-s-triazinetrione, dichlor -s-triazinetrione sodium, sodium dichloroisocyanurate dehydrate, sodium bromide, poly(oxyethylene(dimethyliminio)ethylene(dimethyliminio)ethylene dichloride), 2-(thiocyanomethylthio)benzothiazole, isopropanol, sodium chlorate, sodium n-bromosulfamate, mixture with sodium n-chlorosulfamate, 1,3-dibromo-5,5-dimethylhydantoin, dodecylguanidine hydrochloride, tetrakis(hydroxymethyl)phosphonium sulfate (THPS), 1-bromo-3-chloro-5,5-dimethylhydantoin, sodium chlorite, potassium permanganate, ammonium bromide, copper complex triethanolamine, chlorine dioxide, 2,2-dibromo-3-nitrilopropionamide, 5-chloro-2-methyl-3(2H)-isothiazolone, sodium dichloroisocyanurate dehydrate, silver, sodium silver zirconium hydrogen phosphate (Ag0.18Na0.57H0.25Zr ₂ ( PO ₄ ) ₃ ), amino acids (such as but not limited to: arginine, glutamine, L-lysine, methionine), ethanolamine copper complex, methyldodecylbenzyltrimethylammonium chloride 80% and methyldodecylxylylene bis(trimethylammonium chloride) 20%, lanthanum , aluminum sulfate, 2,4-dichlorophenoxyacetic acid (2,4-D), 1,1'-ethylene-2,2'-bipyridylium dibromide (diquat dibromide), 1-methyl-3-phenyl-5-[3- (trifluoromethyl)phenyl]pyridin-4-one (fluridone), N-(phosphonomethyl)glycine (glyphosate), 5-(methoxymethyl)-2-(4-methyl-5-oxo-4-propan-2-yl-1H -imidazol-2-yl)pyridin-3-carboxylic acid (imazamox), (RS)-2-(4-methyl-5-oxo-4-propan-2-yl-1H-imidazol-2-yl)pyridin- 3-carboxylic acid (imazapyr), [(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid (triclopyr), endothal (3,6-endoxohexahydrophthalic acid as potassium or amine salt), or any combination thereof . Each possibility is a separate embodiment of the invention.

[0166] In some embodiments, the concentration of coating material may be in the range of about 0.5-20% (w/w) of the composition, 0.5-15% (w/w) of the composition, 0.5- 25% (w/w) of the composition, 1-20% (w/w) of the composition, 0.5-5% (w/w) of the composition or any other suitable range within 0.1-40 % (wt./mass.) of the composition. Each embodiment is a separate embodiment of the invention.

[0167] In some embodiments, the coating material may have a distribution coefficient (log P) greater than 1, greater than 1.5, or greater than 2. Each possibility is a separate embodiment of the invention.

[0168] In some embodiments, the concentration of the coating material is less than 30% (w/w), less than 20%, less than 10% (w/w) of the composition, less than 5% (w/w) of the composition , less than 2% (w/w) of the composition or less than 1% (w/w) of the composition. Each possibility is a separate embodiment of the invention.

[0169] In some embodiments, the coating material may include one or more compounds selected from the group consisting of cellulose derivatives, ground plant biomass, saturated hydrocarbons, resinous materials, foam, natural or synthetic latex, waxes, paraffin, rosin, hydrophobic materials, superhydrophobic material, fatty acids and derivatives thereof, and silicone derivatives, or any other suitable compound or combination of compounds having the required critical surface tension described in the present invention. Each possibility is a separate embodiment of the invention.

[0170] In some embodiments, the coating material may be or include a fatty acid. In some embodiments, the fatty acid may be a naturally occurring fatty acid. In some embodiments, the fatty acid may be straight chain. In some embodiments, the fatty acid may have an even number of carbon atoms, from 4 to 28. In some embodiments, the fatty acid may be a long chain fatty acid (LCFA) with aliphatic tails of 13 to 21 carbons. In some embodiments, the fatty acid may be saturated. In some embodiments, the fatty acid may be unsaturated. In some embodiments, the fatty acid may be a triglyceride.

[0171] In some embodiments, the coating material may be or include a wax. As used herein, the term “wax” refers to organic compounds that are lipophilic, plastic solids at ambient temperatures, typically having a melting point between 55-90°C. In some embodiments, the wax may be natural or synthetic. In some embodiments, the wax may be an animal wax, such as beeswax, or a vegetable wax, such as carnauba wax. In some embodiments, the coating material may be or include paraffin.

[0172] Non-limiting examples of suitable coating materials include: decanoic acid, sodium salt; octadecanoic acid, ammonium salt; glycerides, animal origin, reaction products with sucrose; glycerides, palm oil, reaction products with sucrose; glycerides, tall fat, reaction products with sucrose; glycerides, vegetable oil, reaction products with sucrose; fatty acids, tall oil, maleated, compounds with triethanolamine; dodecanoic acid, potassium salt; xanthylium, 3-[(2,6-dimethylphenyl)amino]-6-[(2,6-dimethylsulfophenyl)amino]-9-(2-sulfophenyl)-, internal salt, sodium salt (1:1); siloxanes and silicones, 3-[(2-aminoethyl)amino]propyl Me, di-Me, methoxy at the end; di-2-ethylhexyl azelainate; tetraethoxysilane, hexamethyldissilane polymer; poly(hydroxy-1,2-ethanediyl), alpha-phenyl-omega-hydroxy-, styrene-containing; 9-octadecanoic acid 2-(2-hydroxyethoxy)ethyl ester; isoamyl butyrate; benzenesulfonic acid, octadecyl-, sodium salt; fatty acids, C18 unsaturated, dimers, hydrogenated, polymers with ethylenediamine, 2-aminopropyl Me polyethylene polypropylene glycol ether and polypropylene glycol diamine, minimum number average molecular weight 51300; sulfuric acid, monooctyl ether; siloxanes and silicones, 3-aminopropyl Me, Me stearyl; octadecanoic acid, ester with 1,2,3-propanetriol; 9-octadecenoic acid (Z)-,2,3-dihydroxypropyl ester; octadecanoic acid, 2-hydroxyethyl ester; isopropyl stearate; behenic acid; stearyl alcohol; hexanedioic acid, polymer with N-(2-aminoethyl)-1,3-propanediamine, aziridine, (chloromethyl)oxirane, 1,2-ethanediamine, N,N"-1,2-ethanediylbis-1,3-propanediamine-formic acid and alpha-hydro-omega-hydroxypoly(hydroxy-1,2-ethanediyl); siloxanes and silicones, 3-hydroxypropyl Me, ethers with mono-Me ether of polyethylene glycol; stearyl-dimethyl-benzyl-ammonium chloride, 2; ,3-dihydroxypropyl ester; butyl ester; fatty acids, canola oil; hydrogenated castor oil, polymer with adipic acid, 12-hydroxyoctadecanoic acid; -dimethyl-1,3-propanediol, 1,6-hexanediol, hydrazine, 3-hydro; 9-octadecanoic acid, oxybis(propanediol) monoester; poly(hydroxy-1,2-ethanediyl), α-undecyl-ω -hydroxy-, branched and linear; poly(hydroxy-1,2-ethanediyl), α-(4-nonylphenyl)-ω-hydroxy-, branched; siloxanes and silicones, di-Me, 3-hydroxypropyl Me, 3-hydroxypropyl group at the end, ethoxylated propoxylated; octadecanoic acid, 2,2-bis(hydroxymethyl)-1,3-propanediyl ester; 9-octadecenoic acid, 12-hydroxy-, (9Z, 12R)-, monoester with 1,2,3-propanetriol; glyceryl distearate; fatty acids, coconut, reaction products with 2-((2-aminoethyl)amino)ethanol, bis(2-carboxyethyl) derivative; sorbitan monolaurate; sorbitan monostearate; decanoic acid, calcium salt; fatty acids, tall oil, polymers with bisphenol A, epichlorohydrin, di by-product of ethylene production; glyceryl tris(12-hydroxystearate); siloxanes and silicones, di-Me, Vi group and 3-((2-methyl-1-oxo-2-propenyl)oxy)propyl group at the end; fatty acids, C18-unsaturated, trimers, compounds with oleylamine; sodium lauryl sulfate; laur silt sulfate; siloxanes and silicones, di-Me, polymers with hydrolysis products of 1,1,1-trimethyl-N-(trimethylsilyl)-silanamine with silicon dioxide and trimethylsilyl silicic acid ester; octadecanoic acid, calcium salt; fatty acids, C18-unsaturated, trimers, reaction products with triethylenetetramine; siloxanes and silicones, 3-aminopropyl Me, di-Me, [[(3-aminopropyl)ethoxymethylsilyl]oxy] at the end, 4-hydroxybenzoates; siloxanes and silicones, hydroxy Me, Me octyl, Me(gamma-omega-perfluoro C8-14-alkyl)-oxy, ether; trisiloxane, 1,1,1,3,5,5,5-heptamethyl-3-octyl-; cetyl stearyl octanoate; 9-hexadecenoic acid; phenyl-tris(trimethylsiloxy)silane; octadecanoic acid, 2-ethylhexyl ester; fatty acids, tall oil, esters with polyethylene glycol mono(hydromaleate), compounds with amides of diethylenetriamine and tall oil fatty acids; siloxanes and silicones, di-Me, hydroxy Me, ethers with mono-Bu ether of polypropylene glycol; dodecanoic acid, zinc salt; polypropylene glycol stearyl ether; silane, (3-chloropropyl)trimethoxy-; 9-octadecenoic acid (9Z)-, diester with 1,2,3-propanetriol; polymer based on lauryl methacrylate; butyl acrylate-hydroxyethyl acrylate-methyl methacrylate copolymer; a copolymer of butyl acrylate, 2-hydroxyethyl methacrylate, methyl methacrylate and styrene; copolymer of butyl methacrylate, 2-ethylhexyl acrylate and styrene; hexadecanoic acid, diester with 1,2,3-propanetriol; hexadecanoic acid, a monoester of 1,2,3-propanetriol; sorbitan tristearate; dodecylphenol; dodecylbenzenesulfonic acid, diisopropylamine salt; dodecylbenzenesulfonic acid, triethylamine salt; silane, triethoxyoctyl-; 2-ethylhexyl-12-hydroxystearate; hexadecanoic acid, 2-ethylhexyl ester; 2-ethylhexyl monohydrogen phosphate; magnesium dodecyl sulfate; octadecanoic acid, tridecyl ether; octadecanoic acid, a monoester of 1,2,3-propanetriol; dodecanoic acid, octadecyl ester; silane, trimethoxy(2,4,4-trimethylpentyl)-; C8-12 triglycerides; trisiloxane, 1,3,3,5-tetramethyl-1,1,5,5-tetraphenyl-; sodium dodecylnaphthalene sulfonate; tetradecanoic acid, magnesium salt; heptadecanoic acid; octadecanoic acid, magnesium salt; octadecanoic acid, zinc salt; hexadecanoic acid; octadecanoic acid; octadecanoic acid, 12-hydroxy-, homopolymer, octadecanoate; fatty acids, coconut; fatty acids, vegetable oil; glycerides, sesqui-, hydrogenated tallow; fatty acids, tall oil; fatty acids, tallow; fatty acids, tallow, hydrogenated; fatty acids, soy, ethoxylated; fatty acids, coconut, ethoxylated; siloxanes and silicones, di-Me, Me Ph; siloxanes and silicones, di-Me, hydroxy-terminated, ethoxylated; siloxanes and silicones, Me 3,3,3-trifluoropropyl; poly(methylhydrosiloxane); polydimethylsiloxane, end-capped with methyl groups; chlorinated wax; petroleum wax; paraffins (petroleum), normal C5-20; fatty acids, tall oil, polymers with glycerin, pentaerythritol, phthalic anhydride and rosin; glycerides, mixed mono- and di-; fatty acid; fatty acids, C8-18 and C18 unsaturated; fatty acids, C16-18 and C18 unsaturated; fatty acids, C8-18 and C18 unsaturated, potassium salts; fatty acids, C8-18 and C18-unsaturated, sodium salts; glycerides, C8-18 and C18-unsaturated mono- and di-; glycerides, C14-18 mono- and di-; fatty acids, coconut, polymers with glycerin and phthalic anhydride; silanes and siloxanes, 3-cyanopropyl Me, di-Me, 3-hydroxypropyl Me, ethers with polyethylene polypropylene glycol mono-Me ether; siloxanes and silicones, di-Me, 3-hydroxypropyl Me, ethers with mono-Me ether of polyethylene polypropylene glycol; silicone-glycol copolymer; siloxanes and silicones, di-Me, 3-hydroxypropyl Me, ethers with polyethylene polypropylene glycol; polymer of dimethylsilocean with silicon dioxide; siloxanes and silicones, di-Me, Me vinyl; siloxanes and silicones, di-Me, hydroxy at the end, ethers with mono-Bu ether of polypropylene glycol; siloxanes and silicones, ethoxy Me; glycerides, palm oil mono- and di-, hydrogenated, ethoxylated; glycerides, C16-22; siloxanes and silicones, di-Me, Me hydrogen, reaction products with polyethylene glycol monoacetate; siloxanes and silicones, di-Me, Me hydrogen, reaction products with allyl ether of polyethylene-polypropylene glycol monoacetate; siloxanes and silicones, di-Me, di-Ph, Me Ph, polymers with Me Ph silsesquioxanes; siloxanes and silicones, di-Me, Me Ph, polymers with Me Ph silsesquioxanes; siloxanes and silicones, di-Ph, Me Ph, polymers with Me Ph silsesquioxanes; fatty acids, coconut, diesters with polyethylene glycol; glycerides, C14-18 mono- and di-, ethoxylated; fatty acids, tall oil, esters with ethylene glycol; glycerides, coconut mono- and di-, ethoxylated; glycerides, soy mono-; fatty acids, corn oil; fatty acids, cottonseed oil; fatty acids, soy; fatty acids, tall oil, polymers with ethylene glycol, glycerin, isophthalic acid, pentaerythritol and propylene glycol; fatty acids, tallow, hydrogenated, dimers, diketene derivatives; fatty acids, tallow, hydrogenated, ethoxylated, propoxylated; fatty acids, linseed oil; glycerides, C16-18 and C18-unsaturated mono- and di-; siloxanes and silicones, Me octyl; silane, dichlorodimethyl-, reaction products with silicon dioxide; fatty acids, tall oil, diesters with polypropylene glycol; fatty acids, tall oil, sesqui-esters with sorbitol, ethoxylated; siloxanes and silicones, di-Me, 3-hydroxypropyl Me, ethoxylated; siloxanes and silicones, di-Me, 3-hydroxypropyl Me, ethoxylated propoxylated; siloxanes and silicones, di-Me, [(methylsilylidine)tris(oxy)tris-, hydroxy-terminated, ethers with polyethylene-polypropylene glycol monobutyl ether; fatty acids, coconut, hydrogenated; siloxanes and silicones, di-Me, 3-hydroxypropyl Me, ethers with polyethylene glycol mono-Me ether; fatty acids, tall oil, esters with ethoxylated sorbitol; fatty acids, tall oil, polymers with glycerin, isophthalic acid and rosin; siloxanes and silicones, di-Me, Me hydrogen, reaction products with polypropylene glycol monoallyl ether; glycerides, C14-22 mono-; glycerides, C14-22 mono-, acetates; siloxanes and silicones, di-Me, 3-hydroxypropyl Me, Me 2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl, ethers with mono-Me ether of polyethylene-polypropylene glycol; glycerides, mixed decanoyl and octanoyl; siloxanes and silicones, polyoxyalkylene-; polyglyceryl oleate; polyglyceryl stearate; or any combination thereof. Each possibility is a separate embodiment of the invention.

[0173] In some embodiments, the coating material may be or include behenic acid; octadecanoic acid, 2,3-dihydroxypropyl ester; glyceryl distearate; hexadecanoic acid; octadecanoic acid; fatty acid; fatty acids, C8-18 and C18 unsaturated; fatty acids, C16-18 and C18 unsaturated; fatty acids, C8-18 and C18-unsaturated, potassium salts; fatty acids, C8-18 and C18-unsaturated, sodium salts; glycerides, C8-18 and C18-unsaturated mono- and di-; glycerides, C14-18 mono- and di-; fatty acids, coconut, polymers with glycerin and phthalic anhydride.

[0174] In some embodiments, the coating material may include any compound having one or more of the following: (a) consists of an inert compound(s) of inert components approved for use in pesticide products listed by the US EPA (https:// www.epa.gov/pesticide-registration/inert-ingredients-overview-and-guidance); (b) does not chemically react with DV; (c) low cost; (d) biodegradable; (f) allows the DV to interact with the water system and release its contents over time at water temperatures below 45°C; (f) the percentage coverage (w/w) of the total composition should be below 20%, preferably below 10%, or more preferably below 5%; (g) the by-product of the coating or the combination of the coating with the active substance does not cause harm to the environment; (h) long shelf life (humidity, high temperature during transportation), preferably for 1 year (depending on LW); (i) melting temperature of the coating is 50-90°C; the coating is hard at temperatures above 20°C. Each possibility is a separate embodiment of the invention.

[0175] In some embodiments, the granule size is such that there is an optimal compromise between buoyancy (the smaller the granule, the less it weighs, the more likely it will remain on the surface of the water) and solubility (the smaller the granule, the more surface area, therefore it will dissolve faster). Thus, the size of the granules must be optimized to ensure rapid ascent, while on the one hand allowing the release of DW and on the other hand preventing its diffusion to the water surface in the early stages of the ascent phase.

[0176] In some embodiments, the composition is in the form of granules such as, but not limited to, percarbonate granules.

[0177] In some embodiments, the granule size is in the range of 50-150 microns, 150-1500 microns, 200-1000 microns, 0.3-15 mm, or 1-10 mm. In principle, the larger the granules, the less coating is required. Each possibility is a separate embodiment of the invention.

[0178] In some embodiments, the size of the DV granules can be adjusted so that the composition remains at a depth of 0.02-2 m, 0.1-1.5 m, 0.2-1 m, or 0.2-0. 5 m or any other suitable range between 0.01 and 2 m below the surface of the water system. Each possibility is a separate embodiment of the invention, thus making the composition partially buoyant or semi-buoyant. In some embodiments, at least 99%, 95%, 90%, 85%, 80%, 75%, 70%, 65%, 60%, 55%, 50% of the applied composition may remain semi-buoyant for at least 20 minutes, at least 30 minutes, at least 1 hour, or at least 2 hours after application and/or after ascent. Each possibility is a separate embodiment of the invention. Advantageously, due to the semi-buoyancy of the composition, it is particularly suitable for preventive treatment during the early stages of algae infestation, during which pelagic algae are usually below the surface of the aquatic system, i.e. until algae mats form on the surface of the reservoir.

Methods for introducing a composition

[0179] According to an embodiment of the invention, there is provided a method for treating, inhibiting and/or eliminating the growth of phytoplankton in bodies of water, comprising:

i. testing for the presence of phytoplankton (for example, for certain phytoplankton pigments),

ii. determination of the contaminated area by coordinates,

iii. applying the floating composition locally, with the wind blowing from the shore, opposite the infected area, so that the wind pushes the floating algaecide particles in the direction of flowering,

thereby treating, inhibiting, reducing and/or eliminating phytoplankton growth.

[0180] In some embodiments, the treatment may be prophylactic, allowing treatment with minute doses of the active ingredient. As used herein, the term "preventive treatment" may refer to treatments performed during the early stages of a phytoplankton bloom. In some embodiments, the early stages of a phytoplankton bloom may refer to a phytoplankton concentration of 10 μg/L or lower, 5 μg/L or lower, or 1 μg/L or lower. Each possibility is a separate embodiment of the invention. In some embodiments, the early stages of a phytoplankton bloom may refer to a phytoplankton concentration of 20,000 phytoplankton cells/mL or lower, 8,000 phytoplankton cells/mL or lower, or 5,000 phytoplankton cells/mL or lower. Each possibility is a separate embodiment of the invention.

[0181] In some embodiments, the floatable composition may be a floatable composition as described herein containing an active ingredient (eg, a photosynthetic microbial inhibitor) at a concentration of 80.0-99.5% w/w. and coating material at a concentration of 0.5-20% w/w; in this case, the critical surface tension of the composition is 15-60 dynes/cm, and the relative density of the composition before immersion in water is above 1 g/cm ³ . However, other buoyant compositions, such as, but not limited to, compositions containing at least one buoyant agent and at least one active ingredient, can also be used and are thus within the scope of this invention.

[0182] According to some embodiments of the invention, applying the floating composition includes applying the composition so that the concentration of the active ingredient is less than 999⋅10 ^-9 -10 ^-15 ppm. in the water system.

[0183] In some embodiments, applying the floating composition includes applying the composition to 0.001-10% of the surface of the aquatic system with wind blowing offshore and opposite the contaminated area.

[0184] In some embodiments, a preventative treatment for phytoplankton may include the application of at least two photosynthetic microbial inhibitors, for example, alternately between treatments. As a non-limiting example, two sequential treatments with H ₂ O ₂ -based compositions may be performed, followed by a third treatment with a copper-based composition.

[0185] In some embodiments, a combination of two photosynthetic microbial inhibitors can be applied in a single application, for example copper and H ₂ O ₂ based compositions can be applied simultaneously.

[0186] In some embodiments, the combined or alternating action of more than one photosynthetic microbial inhibitor can (a) prevent the accumulation of resistant strains and (b) affect other phytoplankton species with different susceptibilities, and (c) reduce the total amount of photosynthetic microbial inhibitor applied . Each possibility is a separate embodiment of the invention.

[0187] In some embodiments, the floating composition moves with the bloom in an aquatic system.

[0188] In some embodiments, the method includes periodically treating an aqueous system with a floating composition at a concentration of less than 999⋅10 ^-9 -10 ^-15 . In some embodiments, the method includes periodically treating an aqueous system with a floating composition at a concentration of less than the least lethal dose of an algaecide.

[0189] In some embodiments, a phytoplankton preventive treatment (early season) allows approximately 2 times, 3 times, 5 times, 10 times, 15 times, 20 times, 50 times less active ingredient, or any value in between, to be used per season according to compared to a late bloom treatment (also referred to as a “response treatment” or “late season treatment” in the present invention). Each possibility is a separate embodiment of the invention.

[0190] In some embodiments, phytoplankton preventive treatments completely prevent full-blown blooms.

[0191] In some embodiments, the phytoplankton prophylactic treatment provides at least 40% or at least 50% reduction in phytoplankton biomass after 24 hours. In some embodiments, the phytoplankton prophylactic treatment provides at least 80% or at least 90% reduction in phytoplankton biomass after 48 hours.

[0192] In some embodiments, the treatment will change the ratio between cyanobacteria and non-toxic algae by 2-fold, 4-fold, or more than 10-fold within 24-72 hours of the start of treatment (compared to the ratio before treatment). Each possibility is a separate embodiment of the invention. In some embodiments, the ratio can be determined by measuring photosynthetic pigments (which absorb light energy required for photosynthesis) as representative of certain phytoplankton species, such as: chlorophyll a, chlorophyll b, chlorophyll c1, chlorophyll c2, fucoxanthin, peridinin, phycocyanin, and /or phycoerythrin. Additionally or alternatively, the ratio can be determined spectroscopically by measuring the fluorescence emitted by photosynthetic pigments, or using phytoplankton cell counting (microscopy, cell sorting), or thermal imaging. Each possibility is a separate embodiment of the invention. Without wishing to be bound by any particular theory, the present inventors believe that the treatment methodology and sustained release composition described herein alters the ecological balance of a body of water such that cyanobacteria are lysed or otherwise killed, whereupon non-toxic algae are which are minimally affected by a sublethal dose of DV) gain an advantage and reproduce in large numbers. This "self-healing" mechanism of the pond maintains the treatment and prolongs the results as the increasing fraction of non-toxic algae further competes with the cyanobacteria to keep their numbers low.

[0193] In some embodiments, the method further includes adding an additional dose of the same or a different active ingredient if the phytoplankton biomass is greater than 10 μg/L.

[0194] In some embodiments, a phytoplankton prophylactic treatment eliminates or at least significantly reduces the concentration of toxins in an aquatic system.

[0195] In some embodiments, preventative treatment of phytoplankton eliminates or at least significantly reduces the need for chlorination of water.

[0196] In some embodiments, a phytoplankton preventative treatment eliminates or at least significantly reduces the unpleasant odor and taste of water in an aquatic system, which may be particularly advantageous for recreational and aquaculture purposes.

[0197] Preferably, because the algaecide optimally self-distributes both vertically and spatially, it reduces the overall exposure of living organisms in the water to the active compound and leaves large areas for them to escape upwind or in deep water areas.

[0198] In some embodiments, the phytoplankton preventive treatment further reduces the population of small planktonic crustaceans (e.g., Daphnia species or 0.2-5 millimeter long copepod species) that feed on the phytoplankton (e.g., by at least 10% by at least by 50% or at least 90% within 1, 7 and 30 days respectively). These organisms are a byproduct associated with phytoplankton blooms that increase the incidence of clogged pipes. In some embodiments, the reduced crustacean population in turn reduces the need, or at least the required concentration, of highly toxic pesticides (eg, abamectin) that are commonly used to inhibit, reduce, or kill the growth of planktonic crustaceans. Advantageously, preventative treatment of phytoplankton can thus reduce wear and tear of filters and pumps.

[0199] In some embodiments, prophylactic treatment of phytoplankton further reduces or prevents the occurrence of Enterobacteriaceae species.

[0200] Advantageously, due to the above benefits of phytoplankton preventive treatment, the present invention reduces overall seasonal operating costs by as much as 90%, thereby making treatment of large bodies of water (>10 km ² ) technically, environmentally and financially feasible.

[0201] In some embodiments, the composition can be applied using a “sprayer” similar to those used to spread salt pesticides or agricultural crops. Spraying can be particularly useful when treating large water systems. The composition can be applied from any type of boat without any volume limitation at strategic “drop” coordinates, from where the compound can be distributed by currents and aggregated with algae clusters.

[0202] Also, large quantities of the composition can be manufactured and packaged in silos of variable sizes (eg, 10 tons). Optionally, the entire silage can be transported directly to the desired “drop zone” where it can be disposed. A distributor can be built into such a silo to better regulate the amount and flow of product used in each “dump zone”.

[0203] In some embodiments, the method includes performing follow-up assessments of a previously treated area over a specific period of time, such as 24 hours, 2 days, or a week, to monitor the results of the treatment and respond if, when, and where it occurs. additional dose is necessary. Each possibility is a separate embodiment of the invention.

[0204] In some embodiments, the method further includes conducting a follow-up test every 24 hours, every 2 days, every week, every 2-4 weeks, once a month, once a year, or twice a year to determine whether whether additional processing. Each possibility is a separate embodiment of the invention.

[0205] In some embodiments, the coating method may have one or more of the following features:

- simple and accessible, preferably including no more than two stages,

- safe in production.

Methods for obtaining the composition

According to some embodiments of the invention, a method is proposed for obtaining/manufacturing a floating composition containing percarbonate granules, including heating the DV granules to 45-60°C with continuous stirring in a nitrogen atmosphere in a closed mixer; heating a hydrophobic coating containing methyl esters of fatty acids (CAS No. 67762-38-3) or methyl esters of higher fatty acids (CAS No. 67254-79-9) to 60-90 ° C, encapsulating DV granules using a hydrophobic coating with continuous stirring .

In some embodiments, the method further includes cooling the composition below 40° C. to produce hard-coated sodium percarbonate granules.

[0206] The following examples are provided to more fully illustrate certain embodiments of the invention. However, they should not be construed in any way as limiting the broad scope of the invention. Many variations and modifications of the principles described in the present invention can easily be developed by one skilled in the art without departing from the scope of the invention.

Examples

Example 1 - Determining optimal coverage

[0207] To determine the optimal percentage of coating required to provide (1) float of the composition and (2) sustained release of the compound, the following protocol was established.

[0208] A predetermined amount (by weight) of DV was mixed with the coating material (see Table 1). Although it might be expected that more coverage would lead to better buoyancy, in practice the opposite occurred. Within specific parameters, the less coating material was applied, the better buoyancy was achieved. At the same time, less coverage led to a higher rate of release of active substances from the composition.

[0209] Surprisingly, as can be seen from Table 1 above, when a coating material fraction of 25% or higher was applied to the DV, the final (dry) product lost buoyancy. When submerged in water, it did not float up. When placed on the surface of the water, it sank to the bottom. In addition, the large amount of coating inhibited interaction with surrounding water and thus interfered with the solubilization and release of the active material.

[0210] In contrast, when the proportion of coating used was lower (0.5-20% depending on the nature of the material used), the composition could float despite its specific gravity being higher than 1.0 g/ml. In addition, the agglomerates of the floating composition could release the DV contained in them into the surrounding water. More information is offered in the examples below.

[0211] The floating phenomenon can be seen in FIG. 1A - fig. 1C, which shows example time series photographs demonstrating the buoyancy of granular copper coated with 0, 0.5, 1, 2.5, or 5% (w/w) coating material.

[0212] As expected, the uncoated active ingredient (0.0% (w/w)) immediately sank to the bottom and quickly dissolved in water due to its hygroscopic nature.

[0213] Initial application of 0.5%-5.0% (w/w) formulations produced granules that mostly sank to the bottom (FIG. 1A). However, as can be seen in FIG. 1B and FIG. 1C, within ~30 minutes all the granules that initially sank floated to the surface and mostly remained buoyant.

Example 2 - obtaining a floating composition of sodium dichloroisocyanurate with a high concentration of an inhibitor of photosynthetic microorganisms

[0214] To study the buoyancy of the compositions described in the present invention, an experimental setup was used, schematically illustrated in FIG. 2. In this installation, a laboratory scale 1 (0-2,000±0.1 g) was placed to measure the weight of the composition placed on the scale pan 5, immersed in a glass filled with water 4. If the composition was not buoyant (DV without covering material), expected weight gain (“negative control”). In contrast, if the composition was buoyant, the weight would be expected to remain essentially unchanged.

[0215] The first composition tested was sodium dichloroisocyanurate (SDC) 97% (w/w) encapsulated with wax (3%, w/w). The composition was prepared by melting 3 g of wax in a 500 ml glass. After complete dissolution, DCCN was placed inside the beaker and stirred vigorously for 20 minutes in a standard laboratory chemical fume hood until the temperature of the composition returned to room temperature (22°C). The measured surface tension of the composition was 30 dynes/cm.

[0216] As expected, when 9.5 grams of unencapsulated DCCN was placed on the scale, a weight increase of ~5.3 g was observed. However, when 9.6 grams of the coated sample was weighed, the initial weight increased by only 1.5- 5% of the original weight - apparently due to the semi-buoyancy of the composition on the scales. The critical surface tension of the composition was measured and determined to be 30 dynes/cm.

[0217] FIG. 3A - fig. 3H is a photograph of a time series of coated DCCN (97% w/w DV and 3% w/w coating material) obtained during the experiment. After applying the composition to the surface of the water, the composition initially floated (Fig. 3A). However, soon after application, agglomerates began to form, and a meniscus of the water surface was observed (Fig. 3B, outlined in black in the image). When the water tension was broken during intensive mixing of the water, the composition sank to the bottom within 30 seconds (Fig. 3C - Fig. 3H, follow the arrows). Unexpectedly, after 30 minutes, the DCCN agglomerates floated. By the end of the experiment (after 60 minutes, not shown in Fig. 3), all agglomerates floated.

[0218] Chlorine release rate from DV: when 1.0 grams of encapsulated product (97.5% DV and 2.5% coating material) was placed in a beaker containing 1.0 liter of distilled water under room temperature conditions (22°C ) and vigorously stirred, it took almost 24 hours for all the chlorine to be released into the medium, as measured using a YSI 9300 photometer. In contrast, when the same test was performed using water with a high organic content in the form of 10 ⁷ cells of Planktothrix species per ml, all contained DV was released within 2 hours. These data indicate that the rate of DV release from the encapsulated composition is highly dependent on the organic matter content of the water column in addition to physical parameters such as physical vortex motion in the water.

Example 3 - Industrial production of a floating composition of copper sulfate with high concentrations of an inhibitor of photosynthetic microorganisms

[0219] The final mass of 97.5 kg of granular copper sulfate pentahydrate with a granule distribution of 0.5-5.0 mm was preheated to 50°C in a belt-screw mixer designed for mixing powders. A pre-melted mixture of methyl esters of higher fatty acids (CAS No. 67254-79-9) in an amount of 2.5 kg at 70°C was added to the mixed mixture. The mixture was then stirred for 20 minutes and the contents were then cooled to 22°C (room temperature). For qualitative analysis, three samples of 100 grams each were taken from different places in the batch. The buoyancy of the samples was measured using the experimental setup described in FIG. 2. Preferably, coated samples of the above-described composition exhibited a weight gain of only 31% ± 4%. In comparison, unencapsulated copper showed a 50%±3% increase in weight. The critical surface tension of the composition was measured and determined to be 35 dynes/cm.

[0220] In FIG. 4 shows example photographs of glasses filled with water and compositions (as detailed in Table 1), with decreasing coating percentages (50%, 15% and 2.5% w/w, from left to right). Compositions containing 15% and 2.5% (w/w) coating floated within 30 minutes, while compositions containing 50% (w/w) coating remained on the surface as crystallized agglomerates, which never surfaced. Additionally, unlike the 2.5% and 15% coating compositions, which released their DV content in less than 24 hours (the exact time required was highly dependent on the organic content, as also shown above), the 50% coating composition did not release the DV contained in it for more than 3 days. This was in contrast to the increasing amounts of DV released from the 15% and 2.5% coating formulations, which was evident from the increasingly bluish color of the water column. The water containing the 50% coverage composition remained colorless for at least three days after the time of application.

Example 4 - Industrial production of a floating composition of sodium percarbonate with high concentrations of an inhibitor of photosynthetic microorganisms

[0221] This example details a 98% (w/w) sodium percarbonate (SPC) coating with a 2% (w/w) higher fatty acid methyl ester coating (CAS No. 67254-79-9). Since PCN is an oxygen compound that can explode, precautions have been taken. For this purpose, a closed explosion-proof mixing unit was used, covered with a layer of Teflon and equipped with a vacuum pump for drying purposes. The operating temperature was constantly maintained below 22°C. Organic solvents (e.g., ethanol, methanol, isopropanol) were used in a 1:1 ratio with the coating to melt the coating under ambient conditions. A mixture of 1.0 kg of coating and 1.0 kg of methanol was stirred for 1 hour with 49 kg of sodium percarbonate. After this, the vacuum pump was turned on and all volatile residues were sucked out of the chamber, while the mixture was still shaken in the mixer. After two hours, when the compound was completely dry, the mixer was opened and the compound was packed into 10 kg plastic boxes. The measured surface tension of the composition was 35 dynes/cm.

[0222] In FIG. 5A - 5B show 15 ml tubes each containing 5 grams of uncoated DV (left) or 5 grams of coated DV sample (right), at time 0 (Figure 5A) and after vigorous mixing (Figure 5B ). The DV without coating immediately settled. In contrast, the coated composition formed a meniscus on the surface of the water, partially settled, but floated shortly after. The smaller the coated granules, the faster they floated.

Example 5 - Sedimentation Analysis

[0223] Two 10-liter cylinders were filled with water and sediment was added. Copper sulfate pentahydrate granules were added to one cylinder (mimicking standard processing), while the copper-based buoyant composition was added to the other cylinder. As can be seen in the left image of FIG. 6, sulfate pentahydrate granules immediately settled into the sediment. In contrast, when the copper-based float composition was added (Fig. 6 right image), the composition remained suspended and it released its contents into the water column (from top to bottom).

Example 6 - Large granules float faster

[0224] Two different compositions of granular CuSO ₄ ⋅ 5H ₂ O were purchased from IQV (https://iqvagro.com/en/). Two granule sizes were studied: a) 1.0-10.0 mm and b) 0.280-2.0 mm. The granules were coated with 5% w/w, 10% w/w. or 20% w/w a coating consisting of 67.5% fatty acids and 32.5% fatty acid methyl esters as essentially described in Example 3.

[0225] 150 grams of each composition were tested on the shore of a 150,000 m ² freshwater pond in northern Israel on July 4, 2019. All six formulations were placed in the same manner on a concrete platform approximately 30 cm below the surface of the pond. All six samples were distributed within 2 minutes. The maximum ascent time of the compositions was determined visually and recorded using digital photography. The results are summarized in Table 2.

As observed in Example 1, beads with lower weight percentage coatings floated faster than beads with thicker coatings. In addition, the larger granules (grain size 1-10 mm) unexpectedly floated at a significantly higher rate than the smaller granules (grain size 0.280-2.0 mm).

Example 7 - comparison of anti-algae treatment methods in water storage facilities

[0226] An experiment designed to investigate the preventive approach to control phytoplankton populations described in the present invention was conducted in three wastewater storage facilities with an area of ~50 hectares, a depth of ~15 m (280,000 m ³ ) in Israel (see FIG. 7). The ponds were naturally inhabited by a mixed population of phytoplankton, mainly dominated by Microcystis species during the bloom season. The reservoirs were examined regularly throughout the year in the morning using 3-6 biological samples, and the data were averaged for each sampling day. Samples were analyzed using a YSI Exo-3 sensor, which could simultaneously measure: water temperature, pH, specific conductivity, dissolved oxygen, chlorophyll (in general or specifically chlorophyll b), and phycocyanin (PC) concentrations.

[0227] One pond remained the control and was not treated for the entire year. The other two ponds were treated when cyanobacterial cell densities were typically 40-80 µg/L chlorophyll a visually with the naked eye. Treatment was then carried out at a rate of 5 g/m ² (250 kg/pond or theoretical concentration of 0.89 ppm). The third pond was treated when phytoplankton biomass increased to 5 times its winter baseline. The dosage regimen was calculated as 0.5 g/ ^m2 (25 kg/pond or calculated concentration of 0.089 ppm). All treatments were performed with a floating copper sulfate pentahydrate composition (95% w/w DV, 5% w/w coating).

[0228] Results: In a natural, undisturbed pond, a cyanobacterial bloom developed throughout the year (Figure 7, black curve): although algal cell counts were low during the winter, phytoplankton cell densities continuously increased as temperatures warmed toward spring. Later, as the weather became hotter and the days became longer, the population spontaneously doubled every few hours during the summer, and thus a sharp increase in the number of algae cells became apparent. This phase slowed down towards autumn and reached a plateau mainly when resources became scarce and conditions became less favourable. Throughout the winter, untreated algal cells remained dormant, only to be reborn when conditions improved, and repopulation was observed starting at a higher starting point.

[0229] When the pond was treated solely based on visual inspection indicating the development of cyanobacterial foam, (Fig. 7, gray curve), in early May, the treatment required a high dose of algaecide to be effective. In total, 1.75 tons were applied, which is 875% more than required using the preventive approach described in the present invention (Fig. 7, dashed black line) when only 200 kg were used. In addition, using the preventative approach described in the present invention, total copper concentration measured at a depth of 2 and 5 meters at 2 and 24 hours after treatment was predominantly below the detection level (<0.00 mg/L).

[0230] Moreover, it was found that the non-preventative treatment resulted in a large number of crustaceans (such as Daphnia species) requiring 159 liters of the harsh pesticide, whereas 90 liters of the anti-crustacean compound was required when using the one described herein invention of a preventive approach. Thus, safety and cost-effectiveness from an operational point of view are confirmed (since anti-crustacean compounds are toxic and sometimes even carcinogenic to humans and wildlife).

Example 8 - Evaluation of the effectiveness of a treatment method against cyanobacteria in a large body of water

[0231] The trial was performed in a reservoir with an area of ~1,000,000 m ² (1.5×10 ⁷ m ³ , southern Israel). The reservoir was contaminated by an early mild toxic bloom of cyanobacteria (Anabaena spp. mixed with Aphanizomenony spp.). Based on the water parameters (and taking into account the level of infestation, geological characteristics, local flora in combination with the history of the reservoir), it was decided to use a total of 0.5 g/m ² copper-based floating composition. Within 24 hours of the decision, 500 kg of the composition (95% w/w DV, 5% w/w coating) were transferred in 25 kg bags. directly to the water's edge - where two untrained employees carried and emptied the bags, one by one, into the water (Figs. 8A and 8B). The total application time was <15 minutes. In some cases, the compound settled in the water in large piles (as can be seen). in Fig. 8A).

[0232] Once in the water, the hydrophobic particles immediately began to float and were carried by the southeast wind towards the cyanobacterial aggregates (Fig. 8B). The entire compound, including that in the piles, floated to the surface of the water within 24 hours (as some of the piles were larger than others). This was done to ensure continuous release of the active compound to the water surface and (i) to reduce the cyanobacteria population within 24 hours; and (ii) to achieve a very low (<<0.001 ppb) residual concentration of algaecide in the water within 24 hours of application. Indeed, although the concentration of total copper ions introduced was 0.033 ppm, in practice, during the chemical analysis of water samples taken at a depth of 50 cm and 800 cm from the middle of the pond 24 hours after adding the composition to the surface, it was impossible to detect copper ions. Without wishing to be bound by any particular theory, the present inventors believe that the disappearance of copper ions is likely due to their interaction with abundant organic and inorganic material in the water, which converts the free ions into inert material (see https://www.who .int/water_sanitation_health/dwq/chemicals/copper.pdf).

Example 9 - Evaluation of Low Concentrations and Minimum Coverage of an Anti-Algae Treatment in a Large Irrigation Pond

[0233] A seasonal algal bloom treatment in an irrigation pond with an area of ~1.04 km ² and a volume of 2.25 x 10 ⁶ m ³ (depth 25 m) was carried out from February to October 2017 in the northern Negev Desert, Israel. As shown in detail in FIG. 9, biomass and total copper concentrations were measured during the first two days to assess the effectiveness and minimum required concentrations of the DV. Cyanobacterial biomass was measured using a YSI EXO-3 sensor equipped with a GPS (Global Positioning System). The sensor was installed on a remotely controlled boat, with its help samples were taken throughout the reservoir at a depth of 30 cm and the data was transferred to a laptop computer on shore. Water samples to determine total copper concentrations, as well as to estimate the time of movement of particles through the water, as well as the final coating, were taken from the kayak using a laser distance/range measuring device. Total copper concentrations were measured using a YSI 9300 photometer according to the manufacturer's instructions. To treat the area, 500 kg were added to the surface of the water in 10 kg bags (the entire treatment lasted 25 minutes).

[0234] Once the treatment was implemented, the copper particles moved with the wind and current to the other end of the pond (as summarized in FIG. 9), where they concentrated ~10% away from the contaminated area near the cyanobacterial aggregates. Overall, algal biomass was reduced by >95% within 24 hours without adverse effects on native fauna, birds or fish. After the first treatment (late February 2017), continuous treatment of 125 kg of floating copper sulfate formulation was carried out every 2-3 weeks when algae concentrations exceeded 10 µg/L chlorophyll a. With this treatment regime, the algae cell density did not exceed 10 µg/l chlorophyll a concentrations even at the last measurement at the end of October 2017, and the total amount of copper sulfate used in the floating composition was 1050 kg (95% w/w copper sulfate granules , 5% w/w coating).

[0235] In contrast, in 2016 there were 7 aviation applications of 2000 kg of granular copper sulfate without coating (14 tons in total); however, the average concentration of cyanobacteria remained high (60-80 μg/L chlorophyll a). Similarly, during 2015, 6 aviation applications of granular copper sulfate without coating were carried out, totaling a total of 8000 kg; however, the average chlorophyll a concentration was 100–200 μg chlorophyll a/L.

[0236] Thus, it was concluded that treatment with the floating composition described in the present invention allows maintaining low levels of chlorophyll a, much lower than those measured in 2015-2016, while reducing the amount of copper applied by at least 80 %, and thus dramatically reduce the overall cost and environmental impact of copper ions.

[0237] By summing the data from day 1 and day 2 (FIG. 9), theoretical copper concentrations were calculated which were below 2.2×10 ^-10 ppm. on average over the entire volume of the reservoir (2.25×10 ⁹ liters) for 1 day, and below 4.4×10 ^-11 ppm. on average over the entire volume of the reservoir for 2 days.

[0238] The superiority of the method and composition described herein is particularly surprising when considering other phytoplankton treatment studies that claim that large amounts of Microcystis are reduced solely when H ₂ O ₂ is applied at 4 mg/L and higher, and that the high density of Microcystis cells is quickly restored at the end of treatment (11 days when a dose of 2 mg/l H ₂ O ₂ was applied) (Lin, LZ, et al. (2018) The ecological risks of hydrogen peroxide as a cyanocide: its effect on the community structure of bacterioplankton. J Oceanol Limnol 36: 2231–2242).

Example 10 - Treatment of a pond infected with Microcystis species

[0239] An irrigation pond contaminated with a 98 µg/L chlorophyll a bloom of Microcystis spp. in the Southern Negev, Israel, was used in November 2017. The surface area of the pond was 75,000 m ² and the total reservoir volume was 1,125,000 m ³ . 150 kg of the floating composition described in the present invention (95% w/w copper sulfate granules, 5% w/w coating) was added, the total copper level was 2.0 g/m ² . Four hours after treatment, total copper concentrations at 7 m depth were predominantly below YSI 9300 photometer detection levels (<0.00 ppm). Two and a half hours after treatment, the concentration of copper at the surface where the floating composition was applied was 3 ppm, but below detection levels at a depth of 7 m. The overall reduction in cyanobacterial biomass after two days was 97% (see Fig. 10). Dead cells were observed floating on the surface of the water, where they were consumed by heterotrophic bacteria. It was calculated that the total theoretical concentration of copper after 2-3 hours of treatment was 1.3×10 ^-9 ppm. on average over the entire volume of the reservoir.

Examples 11 - Lake Treatments

[0240] Lake Chippewa (Ohio, USA): 1.3 ^km2 , has been plagued by algal blooms in recent years, preventing lake recreation for much of the season. A report prepared for Medina County in May 2019 listed several alternative treatments costing between $0.5 million and $1.8 million, none of which were feasible or economical. From an operational point of view and in terms of its size, the lake fell into the category of “incurable lake”.

[0241] In order to highlight the simple scalability of the method and compositions described in the present invention (95% w/w copper sulfate, 5% w/w coating), a lake cleanup was undertaken. The treatment was carried out after a surge in cyanobacterial biomass in the lake was recorded, reaching an alarming level of 280,000 cells/ml (14 times higher than normal), corresponding to an increase in cyanotoxin levels from 0.18 ppm. up to 0.25 ppm during one week. A spike in cyanobacteria levels was visible to the naked eye, with cyanobacterial mats found on the eastern shore of the lake, consistent with NOAA satellite imagery acquired on August 3 (Figure 11) - indicating high levels of cyanobacteria that covered more than 50% of the lake's surface.

[0242] Sampling method: Using the YSI ProDSS sensor, dissolved oxygen (DO), pH, chlorophyll b (Chl b is an indicator for determining the total biomass of green algae), phycocyanin (PC is an indicator for determining the total biomass of cyanobacteria) were measured. Clogging Potential Indicator: A quantifier of the total solids in water, measured as the time it takes for water to clog a filter at constant pressure. Microscopy: taking qualitative samples of microorganisms in an aquatic environment. Total phytoplankton was concentrated on a 33 µm filter using a 3-4 gallon sample. Secchi Disc: Measures water clarity/turbidity. Satellite imagery for toxic cyanobacterial outbreaks (TCB) (provided by NOAA). Enzyme immunoassay for microcystin, cyanotoxin. This test measures microcystin levels in water. Samples were collected weekly at two fixed locations on the east side of the lake (provided by the Medina County Park District). YSI 9300 Photometer: Measures total copper ion (Cu), hydrogen peroxide (H ₂ O ₂ ) and alkalinity.

[0243] Beginning on August 5, 2019, all measurements, with the exception of satellite imagery and enzyme immunoassays, were taken daily for 9 days at 8 a.m. each morning at four different sampling points around the lake. Cyanotoxin levels (enzyme-linked immunosorbent assay) and total cyanobacterial mat coverage of water surfaces (satellite imagery) were assessed independently by local authorities.

[0244] An estimate of the first application of ~0.9 lb/acre was made on day 3, August 7th, to determine wind and current directions and dispersion patterns across the water surface. Operational application followed on August 8th at a rate of 4.5 lb/acre. The results were analyzed and normalized to day 3.

[0245] Method of application:

[0246] The composition described herein (here, 95% w/w copper sulfate granules, 5% w/w coating) was applied directly from the boat in the morning hours at a total dose rate of ~5 lb/acre. The product, packaged in 50-pound bags, was released by gravity from the edge of a moving boat. As soon as the product was distributed through the water along the western perimeter of the lake, it was carried by winds and currents, which dispersed the floating particles along with aggregates of cyanobacteria. The total application time for 1,500 pounds of composition was less than 30 minutes. For several hours no algaecide particles were visible to the naked eye. Boat activity was not interrupted during the application period. Measurements taken two hours after treatment showed negligible levels of copper ions (average 0.3 ppm) in the immediate hours after treatment, which dropped below detection limits the following day.

[0247] Results and discussion:

[0248] Post-treatment assessments of phytoplankton showed a clear and immediate shift from dominant toxic cyanobacterial species (primarily Anabaena spp. and Planktothrixy spp.) to a beneficial diversity of eukaryotic, non-toxic green algae, including diatoms and various Chlamydomonas-like species (Fig. 12) Interestingly, non-toxic cyanobacteria spirulina species have also been observed after processing. This strain is used as a "superfood" and is not considered toxic.

[0249] Changes in chlorophyll b (Chl b) and phycocyanin (PC) levels were highly correlated with qualitative results obtained from microscope images. The lake's "resistance index" to cyanobacteria, which can be assessed by the ratio between chlorophyll b and FC (total eukaryotic green algae biomass compared to cyanobacteria biomass), increased significantly by 250% (Fig. 13), indicating a clear shift in equilibrium forces between these two natural competitors in favor of non-toxic species.

[0250] An enhanced post-treatment cycle, namely a post-treatment drop in cyanobacterial populations followed by prolonged oxidative stress due to hydrogen peroxide production, which again leads to programmed cell death of naïve cyanobacterial populations, was observed in Chippewa Lake several days after treatment. Tens of acres of water surface were covered with a grayish-beige protein-based foam (Figure 14). This phenomenon is due to lysis of cyanobacterial cells and is a clear indication that cyanobacterial cell death continued to progress for several days after treatment, long after copper levels were not detectable in the water (as detailed later in the present invention).

[0251] Microcystin levels remained very low after treatment (Figure 15), indicating that timing of treatment early in the bloom burst was effective. The sharp decrease in cyanobacterial biomass did not result in an increase in cyanotoxin levels, confirming that cyanobacterial cells were in their latent phase when the accumulation of cyanotoxins in cells is minimal (Wood et al., 2010). If the treatment had been carried out a week or two later, during the exponential growth phase of the toxin-producing cyanobacteria, cyanotoxin levels could have been much higher.

[0252] Post-treatment pH levels decreased from pH 8.5 to pH 7.95 (August 9-11), the result of a decrease in total photosynthetic activity (as an indicator of the relative decrease in total phytoplankton biomass). Within 4 days (August 12), pH levels rose to pH 8.35, indicating the resumption of photosynthetic activity by a new, predominantly nontoxic phytoplankton species (Figure 12 and Figure 13).

[0253] Further supporting the benefits of early treatment and its impact on the aquatic environment, resulting from consistent dissolved oxygen levels before, during and after treatment (FIG. 13), is the avoidance of the risk of fish mortality due to oxygen depletion (a common consequence of bloom declines). In fact, there was no evidence of any adverse effects on the fauna or flora of the lake.

[0254] The clogging potential indicator, which indicates the total amount of solids in the water, was significantly improved by 400% immediately after treatment (Fig. 13). This measurement provides an additional indicator of changes in populations favoring non-toxic species: cyanobacteria are known to release significant amounts of polysaccharides into water (Harel et al., 2012), which increase water viscosity and are associated with the unpleasant phenomenon of swimmer's itch. Regulating the concentrations of polysaccharides in water due to the decline of cyanobacterial communities overcomes another “wall” in the protective mechanism of cyanobacteria against their natural competition, further increasing the “resistance index” to cyanobacteria. Disruption of this polysaccharide production network contributed to increased water filterability, as indicated by the clogging indicator results. The concentration of copper ions (Cu ²⁺ ) in water sampled 15-30 cm (6-12 inches) below the water surface 1-2 hours after application averaged approximately 0.3 ppm. The concentration of copper ions on days 1-3 after treatment was <0.00 ppm. Water alkalinity levels remained unchanged before and after treatment, in the 80 ppm range. (mg/l).

[0255] Overall, the above results indicate that the compositions and method of administration described herein were selective against toxic cyanobacteria and restored the ecological ecosystem in the lake in favor of beneficial species, which then acted as a biological buffer against re-establishment of dominance cyanobacteria in an aquatic system. Surprisingly, the effect of the treatment was still present at the last measurement in January 2020, thus confirming that the lake is “self-healing” by restoring a desired and sustainable ecological balance.

[0256] Israel, Nitzanim Reservoir (seasonal treatment):

[0257] The Nitzanim Reservoir holds water for irrigation purposes. Preventing blooms in the reservoir is key to its continued operation. It is required to supply water to its customers that meets both bacterial and filterability standards at all times.

[0258] Israel Water Associations operate approximately 600 reservoirs (10-190 acres in size) throughout the country designed to retain and manage recycled wastewater for irrigation.

[0259] Outbreaks of cyanobacterial blooms occur regularly in these reservoirs, likely for many reasons, including high levels of nutrients (e.g., phosphates and nitrates), high temperatures, and sunlight intensity. It is noteworthy that the alkalinity of the water is very high, in the range of 500-800 mg/l CaCO ₃ .

[0260] For many years, Israel's irrigation ponds have been continuously treated with raw copper at rates of 10-20 kg/acre (20-40 lb/acre); applied either from spraying aircraft or manually from a boat. Treatment efficiency was quite low, thus requiring frequent treatment. In many cases, senior technicians are forced to open and clean pumps and filters, sometimes daily, to keep the water flowing. As a result, when water levels decline toward the end of the irrigation season, most reservoirs are forced to stop flow due to thick algae blooms that clog and damage pumps.

[0261] Materials and methods:

[0262] The reservoir has a surface area of 15 acres and a depth of approximately 50 feet (~2.6 million cubic feet). Monitoring was carried out 2-3 times every week between January and June 2018.

[0263] Measurements:

[0264] - Chlorophyll a (as an indicator of total phytoplankton) was measured using a portable device (FluoroSense™, from Turner Designs, USA).

[0265] - pH

[0266] - Temperature

[0267] - Total solids were assessed using a clogging potential indicator (Israel Water Works Association, Israel) with a 33 μm strainer. This device measures the time it takes for a sieve to clog under constant water pressure. In general, the longer the filter is clogged, the better the water quality.

[0268] A water sample was taken from an intake stream at a fixed location in the middle of the reservoir 6 feet above the reservoir bottom and 45 feet below the surface at full reservoir.

[0269] Sampling was carried out in triplicate. All results were averaged for each sampling point. Algal population analysis was performed by observing through a microscope using a hemocytometer chamber to count cells.

[0270] Processing protocol

[0271] Treatments were carried out in accordance with the state of the algae biomass, as well as the state of water filterability. The presented parameters were measured in the field and in the company’s laboratory.

[0272] Results and conclusions:

[0273] A mixture of toxic cyanobacteria species (Anabaena spp. and Microcystis spp.) comprised more than 95% of the total phytoplankton populations in the reservoir prior to treatment.

[0274] Initial treatment with the compositions described herein (first treatment with a composition of 98% w/w sodium percarbonate and 2% coating material followed by treatments with a 95% w/w coated copper sulfate composition as indicated in FIG. 16) caused a general drop in toxic blooms, which remained below dangerous levels for the next few months (Fig. 16). Analysis of the phytoplankton population clearly showed that the treatment effect emphasized the kill-the-winner paradigm, such that the treatment strongly impacted the dominant species, allowing harmless eukaryotic algal species, mainly Monorapridium spp. and Pediastrum spp. (much less sensitive to processing), occupy a “free” ecological niche (Fig. 16).

[0275] Preferably, the total amount of copper applied in 2018 using the composition described in the present invention was 1/3 of what was applied the year before (Fig. 17), despite the increase in toxic blooms in a nearby body of water. Considering the ~200% annual increase in cyanobacteria populations in various water bodies in Israel between 2014-2017, the actual reduction in copper applied in 2018 using Lake GuardTM was close to ~85%.

[0276] Since its launch in Israel in mid-2018, the composition described herein (containing 98% (w/w) sodium percarbonate) has captured ~90% market share at record speed.

[0277] China, Lake Taihu (near Yixing): a pilot test was performed in an old fish pond (7100 m ² , ~2 acres), near Lake Tai, throughout the area like a polluted "corridor" connecting the waterway between the city of Yixing and the lake Tai. Ongoing efforts to control the multitude of cyanobacteria flowing through this "corridor" from both the lake and the city, at an average annual cost of $25 million, have been unsuccessful.

[0278] A fish pond that was contaminated with a very large biomass of cyanobacteria was treated with a high dose to achieve an immediate reduction in biomass levels.

[0279] Since launch in June 2019, there have been multiple applications in different installations in China. A recent example is from a pilot study designed to prepare a waterway cleanup project in Yixing (Fig. 18), on the shores of Lake Tai, one of the most famous and worst cases of large-scale algal blooms (~2250 km ² ).

[0280] Description of application:

[0281] The fish pond was dosed with the composition described herein (98% w/w sodium percarbonate and 2% coating material) on August 7 and August 8, 2019.

[0282] Particles of the composition were introduced so that they moved with currents and wind across the pond, interacting with the phytoplankton inhabiting the pond. Two sequential treatments were carried out. Each application lasted less than 5 minutes. By midday on August 8th, ~6 hours after the second application, all water parameters indicated a complete drop in bloom. One example (Fig. 19) is an initial decrease in chlorophyll and a sharp decrease in phycocyanin, which reflects changes in phytoplankton and cyanobacteria levels, respectively.

[0283] After two weeks, the phytoplankton population of eukaryotic green algae showed remarkable recovery, with beneficial species replacing and likely displacing toxic cyanobacteria and maintaining a healthy aquatic ecosystem (FIG. 19).

[0284] Sampling procedure:

[0285] During the trial period, quantitative measurements were performed using a YSI ProDSS sensor that measured dissolved oxygen, pH, chlorophyll, and phycocyanin (PC). Chlorophyll (Chl) measurements served as an indicator of the total algal biomass in the water. Phycocyanin (PC) levels served as a direct indicator of total cyanobacterial biomass.

[0286] In parallel, qualitative assessments were carried out visually.

[0287] Results:

[0288] A. Changes in Cyanobacteria Levels and Total Algae Levels:

[0289] Before treatment (at time 0), PC and chlorophyll values were 21.84 μg/L and 22.32 μg/L, respectively. After 48 hours, FC had decreased to 1.72 μg/L (~93% of time 0) and chlorophyll concentration was 9.39 μg/L (~58% of time 0) (Fig. 19A and FIG. 19B).

[0290] Two weeks later, on August 20th, FC values continued to remain unchanged at 2.04 μg/L, while chlorophyll concentration increased to 45.34 μg/L (i.e., a 482% increase from the lowest point after processing). Since PC levels did not change significantly over the two weeks, the significant increase in chlorophyll levels reflects an increase in beneficial algal populations relative to cyanobacterial species.

[0291] B. Changes in pH and dissolved oxygen (DO):

[0292] The sharp decrease in photosynthetic and respiratory activities (CO ₂ uptake and release, respectively) had an immediate and direct effect on the pH (Figure 20A), which decreased from 9.05 to 8.29 within 48 hours. By August 20th, two weeks later, pH levels had dropped to 7.43.

[0293] Dissolved oxygen (DO) levels decreased immediately after treatment due to the bacterial-mediated biodegradation of dead cyanobacteria biomass, which consumes dissolved oxygen, and due to the decline of oxygen-producing cyanobacteria. However, DO levels gradually increased from the lowest point on day 2 as oxygen-producing algae began to develop in the rebalanced aquatic ecosystem - as indicated by an increase in chlorophyll levels, but not PC levels (Fig. 20B).

[0294] Visual inspection of the pond before treatment (top panels) and after treatment (bottom panels) confirmed the effectiveness of the treatment (FIG. 18).

[0295] Russia, recreational lake in Victory Park (Republic of Tatarstan):

[0296] Treatment and follow-up took place between October 2 and October 10, 2018.

[0297] The size of the lake was 40,000 m ² surface area (10 acres).

[0298] Enter:

[0299] Application of the composition described herein (98% w/w sodium percarbonate) at 8 lb/acre was carried out manually on the morning of October 2, 2018 from the shores of a lake by an untrained local resident. Application took less than 10 minutes. As wind and currents pushed the slow-release floating particles through the water, they themselves collected together with the cyanobacterial aggregates.

[0300] Sampling procedure:

[0301] The lake has been inspected on a regular basis over the past year by a local inspector.

[0302] Results: There were no adverse effects on fauna or flora in or around the pond according to lake inspector reports (September 2019), and no blooms were observed in the lake since a single treatment with the composition described in the present invention in October 2018, the year previously. This is in stark contrast to previous years, when harmful algae blooms damaged the lake every year.

[0303] While certain embodiments of the invention have been illustrated and described, it should be made clear that the invention is not limited to the specific embodiments described in the present invention. Numerous modifications, alterations, variations, substitutions and equivalents will be apparent to those skilled in the art without departing from the spirit and scope of the present invention as described in the following claims.

Claims (23)

1. A composition for weakening, inhibiting and/or eliminating the growth of phytoplankton in a reservoir, containing granules containing the active substance in concentrations of 80.0-99.5 wt.% of the composition and a hydrophobic coating material in a concentration of 0.5-20 wt.% of the composition ; wherein said active substance is encapsulated with a hydrophobic coating material; wherein said active ingredient includes a peroxide-based algaecide, a copper-based algaecide, an aluminum-based algaecide, or any combination thereof; wherein said active substance is characterized by a specific gravity of more than 1.0 g/ml; wherein said hydrophobic coating material includes a fatty acid, a fatty acid derivative, a wax, a paraffin, a rosin, a silicone derivative, or any combination thereof; wherein said hydrophobic coating material has a specific gravity of less than 1.0 g/ml. 2. The composition according to claim 1, characterized in that the hydrophobic coating material has an acid value of 3-8 mg KOH per gram. 3. Composition according to any one of paragraphs. 1 or 2, characterized in that the fatty acid derivative includes 2,3-dihydroxypropyl octadecanoic acid; fatty acid methyl ester; glyceryl distearate; C8-18 and C18 unsaturated mono- and di-glycerides; C14-18 mono- and di-glycerides; polyethylene glycol diesters of coconut fatty acids, ethoxylated mono- and di-glycerides of coconut fatty acids, or any combination thereof. 4. Composition according to any one of paragraphs. 1-3, characterized in that the hydrophobic coating material has a melting point of 50-90°C and the hydrophobic coating material has a pour point below 20°C. 5. Composition according to any one of paragraphs. 1-4, characterized in that said active ingredient includes a peroxide-based algaecide, a copper-based algaecide, or any combination thereof. 6. Composition according to any one of paragraphs. 1-5, characterized in that the concentration of the active substance is 90-99.5 wt.% and the concentration of the hydrophobic coating material in the composition is in the range of 0.5-10 wt.%. 7. Composition according to any one of paragraphs. 1-6, characterized in that these granules have a size in the range of 0.1-10 mm. 8. Composition according to any one of paragraphs. 1-7, characterized in that these granules have a size in the range of 1-10 mm. 9. Composition according to any one of paragraphs. 1-8, wherein said hydrophobic coating material comprises a fatty acid, a fatty acid methyl ester, a fatty acid triglyceride, a wax, or any combination thereof. 10. Composition according to any one of paragraphs. 1-9, characterized in that it contains granules having 0.5-2 wt.% hydrophobic coating material, mixed together with granules having 3-10 wt.% hydrophobic coating material. 11. A method for preventing and/or inhibiting the development of toxic phytoplankton blooms in a reservoir, including identifying areas in the reservoir having a toxic phytoplankton biomass above 8000 cells/ml or a chlorophyll a concentration above 3 μg/l, and introducing a composition according to any one of claims. 1-10 per area of the reservoir so that the concentration of the algaecide in the area of the reservoir is in the range of 10 ^-7 -10 ^-12 ppm. within 24 hours, thus providing a prolonged release of the algaecide. 12. The method according to claim 11, characterized in that the body of water includes a reservoir, ocean, lake, dam, pond, estuary, bay, sea or river. 13. The method according to claim 11 or 12, characterized in that the application is carried out when the concentration of chlorophyll a is below 10 µg/l. 14. Method according to any one of paragraphs. 11-13, further comprising applying a second dose of said composition to the area 0.5-10 hours after its first application. 15. Method according to any one of paragraphs. 11-14, characterized in that said composition is designed to release the algaecide within at least 2 hours after its application. 16. Method according to any one of paragraphs. 11-15, characterized in that said composition is formulated to remain submerged to a depth of 0.02-1 m below the surface of the reservoir. 17. Method according to any one of paragraphs. 11-16, characterized in that the reservoir is a reservoir with early cases of toxic phytoplankton blooms. 18. Method according to any one of paragraphs. 11-17, characterized in that the composition contains granules having 0.5-2 wt.% hydrophobic coating material, mixed with granules having 3-10 wt.% hydrophobic coating material, which leads to a slow release of the algaecide and/ or a long period of exposure of cyanobacteria to the algaecide. 19. The method according to claim 18, characterized in that the hydrophobic coating material has a melting point above 45°C. 20. Method according to claim 18 or 19, characterized in that the hydrophobic coating material has an acid value of 3-8 mg KOH per gram. 21. Method according to any one of paragraphs. 11-20, characterized in that the critical surface tension of said composition is 15-60 dynes/cm, and the relative density of the composition before immersion in water is above 1.0 g/cm ³ . 22. Method according to any one of paragraphs. 11-21, characterized in that the size of the granules in the composition is in the range of 0.1-10 mm.