MXPA98000758A - Particulate materials that float in water, which contain micro-nutrients for fitoplanc - Google Patents

Abstract

The present invention relates to compositions that float in water, comprising a source of micronutrients for the growth of photosynthetic phytoplankton, which are useful for stimulating the growth of photosynthetic phytoplankton in areas of the ocean devoid of such growth, when they are deployed on surfaces of the ocean as floating particles. Iron is the preferred micronutrient

Description

PARTICULATE MATERIALS THAT FLOAT IN WATER, WHICH CONTAIN MICRO-NUTRIENTS FOR FITOPLANCTON FIELD OF THE INVENTION The present invention relates to materials that contain a source of micronutrients, in the form of floating particles. The invention also relates to the preparation of such materials, and to their use to stimulate the growth of photosynthetic phytoplankton in areas deficient in micronutrients of the oceans or other water bodies. ANTECEDENT TECHNIQUE It is known that iron is an essential micronutrient for the photosynthetic growth of phytoplankton (algae) in global water, particularly the oceans. More than a fifth of the world's oceans have iron-deficient surface waters, with little or no algal growth, despite the presence of all other nutrients essential for growth (Kolbert et al., Nature 371, 145 (1994)). These regions have been called areas with high nitrate content, low chlorophyll content (HNLC). Martin and others have suggested adding iron to the ecosystems of these ocean areas, to stimulate the growth of phytoplankton on a scale sufficient to affect the carbon dioxide level REF: 26341 atmospheric, which in turn may be useful to help prevent global warming. See, for example, Martin, J. H. et al., Nature 371, 123 (1994). A major "sowing iron" experiment conducted in 1993 in an area of the equatorial Pacific Ocean, currently devoid of algae, showed that the addition of iron produced an immediate and dramatic growth of phytoplankton. The effect, however, was short-lived. A major reason was the rapid loss of iron. The loss of iron was attributed to the sinking of iron in deeper water and / or the possible adsorption of iron by the organic material (Van Scoy, K. Et al., New Scientis, page 32 (December 3, 1994), Martin, JH et al., Nature 371, 123 (1994)). Little effect was detected on surface carbon dioxide concentrations, presumably because of the short-lived nature of the experiment (Atson, A. J. et al., Nature, 371, 143 (1994)). Wells, M. et al., In Nature, 353, 248 (1991), describe that the availability of iron as a micronutrient for the growth of algae depends on their chemical lability and / or ease of dissolution. Natural sources of iron are often in refractory, particulate or colloidal free form, not available for direct assimilation by phytoplankton. Such forms are eventually converted by natural means into bioavailable forms, but at a slow and unpredictable rate. There must be chemical reactions that require time before this iron is "bioavailable", that is, converted to a form that can be used in photosynthesis. Much "natural" iron is lost by sedimentation or other means before such conversion is completed. Johnson, K. S. et al., In Marine Chem. 46, 319 (1994), discloses that particulate iron or colloids must be at least partially solubilized for bioavailability, to support the growth of phytoplankton. Experiments where the addition of iron gave rise to a rapid, albeit temporary, growth of algae have employed soluble iron or ferrous salts such as ferrous sulfate dissolved in acidified sea water (Van Scoy et al., Supra). Although the prior art has shown the positive impact on photosynthetic growth of adding nutrients such as iron, the nutrient sources were supplied in a non-floating form. The non-floating sources sank quickly and disappeared from the growing sites, after which photosynthesis declined rapidly. Alternatively, to mimic the main source of natural iron to remote areas of the world's oceans, atmospheric dust particles were added as aerosols. Such particulate iron sources, although mostly refractory (not labile), contributed to the photosynthetic growth of phytoplankton, as measured by chlorophyll production. See K. S. Johnson et al., Supra. It was found that photochemical reduction contributed to the bioavailability of particulate iron. It is the purpose of the present invention to artificially provide micronutrients to phytoplankton on a more continuous or sustained basis. Buoyant or waterborne compositions containing micronutrients for photosynthetic growth such as iron will remain longer in surface waters, and thus may increase the availability of nutrient iron for photosynthetic processes. Floating materials containing a source of one or more elemental nutrients, especially iron, on or near the surface of bodies of water deficient in such elemental micronutrients will stimulate and maintain the effective photosynthetic growth of phytoplankton for a sustained period of time.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides a composition that floats in water, which provides a sustained source of micronutrients for the photosynthetic growth of phytoplankton. Such a composition may additionally comprise a particulate substrate floating in the water, chemically inert, relatively insoluble in water, to support the source of the micronutrient. The compositions or materials containing the micronutrient source present, which float in the water may conveniently be in the form of an aqueous dispersion, in the form of dry, free-flowing particles, or an equivalent form. The compositions may, optionally, further comprise water soluble agents that temporarily seal the source of particulate micronutrients and / or provide a slow release of the micronutrient source from the support substrate in the surrounding body of water. The invention also provides a process for preparing compositions containing a source of micronutrient that floats in water, the process comprising mixing and impregnating a substrate material, comprising relatively water-insoluble, chemically inert particles floating in the water, with an aqueous solution or dispersion of one or more compounds that are a source of at least one micronutrient of the photosynthetic phytoplankton. The invention also provides a process for increasing the biomass of oceanic plankton and / or decreasing atmospheric carbon dioxide by applying compositions containing a source of micronutrients to bodies of fresh or salt water, for example lakes, bays, gulfs, or oceans. In the case of very large areas of oceans, for example, in the equatorial Pacific, the North Atlantic, or the Arctic or Antarctic regions, the effect on the reduction of atmospheric carbon dioxide can be significant. The invention, therefore, can provide a way to combat the elevation of anthropogenic carbon dioxide in the atmosphere, which can otherwise contribute to global warming, just as in the past, a decrease in atmospheric carbon dioxide. place at the beginning of the glacial periods. The particulate material according to the present invention can be applied to the surface of a body of water as a liquid dispersion, or the material can be first dried and applied to the body of water as free flowing particles. Optionally, one or more water-soluble agents, which temporarily seal the micronutrient source compounds and / or promote their durable adhesion to the substrate, or their slow release into the ocean, can be added to a solution or dispersion containing micronutrients before their mix with a substrate.

Alternatively, such agents can be applied to the particulate product after drying. A further objective of this invention is to provide compositions that float in water, which contain the source of the micronutrient, comprising low cost, and abundant materials that will not have a negative environmental impact on the intended use. Still a further objective of the invention is to stimulate the growth of plankton in bodies of water, increase their biomass for environmental reasons, and / or increase their harvest of marine food or fresh water for human consumption. Still a further objective of the invention is to stimulate photosynthetic growth on a scale large enough to cause a global reduction in atmospheric carbon dioxide.

DETAILS OF THE INVENTION The present invention provides a source of micronutrients for photosynthetic growth. The source of the micronutrient is contained in a material that floats in the water, which allows the micronutrient to be used more gradually and totally in photosynthesis. More specifically, the invention provides a composition floating in water, made artificially, which comprises a source of micronutrient for the growth of photosynthetic phytoplankton. Preferably, the composition further comprises a particulate substrate floating in the water, chemically inert, relatively insoluble in water, resistant to wear, to support the source of the micronutrient. The source of the micronutrient is a compound or mixture of compounds that is in a form that is either bioavailable or readily available to be bioavailable under the environmental conditions prevailing in use. The main purpose of the floating compositions of the invention is to facilitate an efficient and continuous supply of a source of photosynthetic micronutrient in the vicinity of the air / water interface of a body of water. The emphasis of the present invention is on iron (Fe) as the micronutrient, for which there is a clear need in most of the world's oceans. However, it will be understood that other sources of elemental nutrients such as cobalt, manganese and zinc (Martin et al., Deep Sea Res., 36, 666-667 (1989)) could be similarly retained, alone or in combination with other micronutrients , in compositions that float in water. By "floating in the water" is meant the ability to float on water for a substantial period of time. Such materials will normally have a density of less than 1000 kg / m3 in the case of fresh water, and a density of less than 1030 kg / m3 in the case of salt water. By the term "micronutrient" or "elemental micronutrient" is meant an element that is essential in trace quantities for the growth of phytoplankton. For example, iron (Fe) plays a crucial role in the bioenergetics of carbon and nitrogen metabolism, and is required for the synthesis of chlorophyll and the reduction of nitrate. Other micronutrients include Co, Mn, Zn. For example, cobalt is required for the synthesis of vitamin B 2, and manganese is essential for the activation of enzymes. The preferred nutrient, however, is iron, either alone or in combination with other micronutrients. In the case of relatively smaller bodies of water, such as lakes and bays, it may also be desirable to include phytoplankton nutrients such as phosphates or nitrates in the materials or compositions of the present invention. By "micronutrient source" is meant one or more metals or compounds thereof, which provide one or more elementary micronutrients essential for photosynthetic growth, either in a bioavailable form or in a form that is convertible to a bioavailable form during its use. By "bioavailable" is meant in a form that is usable in the process of photosynthetic growth by phytoplankton. By the term "relatively insoluble", referring to a substrate, it is understood that the substrate remains largely insoluble during the time it releases its micronutrients. The substrate may eventually decompose and / or dissolve for a longer period of time, for example, as a result of its exposure to the sun and to naturally occurring chemical compounds. By the term "substrate" is meant the floating material from which the claimed composition is made, in the absence of the source of the micronutrient.

The present compositions floating in the water can be prepared in various ways, several of which will be apparent to those skilled in the art in view of the examples presented herein. The applicant emphasizes that the following details of the process and example are proposed so as to be illustrative only, and not to limit the scope of the invention. The preferred process for preparing the present materials is by mixing a particulate substrate material floating in the water, chemically inert, relatively insoluble in water, with an aqueous solution or dispersion of one or more compounds that are a source of at least one micronutrient for photosynthetic growth, to provide an aqueous dispersion of particles, wherein a source of micronutrient is supported on the substrate by the particles floating in the water. The aqueous dispersion of particles of the invention can be applied "as is" to the surface of a body of water, or it can be dried and applied to water as free-flowing particles. Optionally, one or more water soluble agents that seal the micronutrient source compounds and / or promote the durable adhesion of the micronutrient source compounds to the substrate and / or cause the slow release of the micronutrient source compounds can be added to the solution or dispersion containing the micronutrient source before it is mixed with a substrate, or it can be applied to the particulate product after drying. Preferred water-insoluble substrates in water are low-cost, abundant, chemically inert materials, such as finely divided polymeric foam materials, ash dust (from electro-commercial companies that burn coal) and materials derived therefrom, hollow glass particles, plant cellulosic materials, or other low-cost sources of particles that float in water. By the term "glass" is meant an amorphous, rigid, inorganic solid, which may or may not be translucent. It would be desirable to produce commercial quantities of the product according to the present invention, in batches or commercial quantities of at least one metric ton. To regulate ocean areas, the total amount of material used would, of course, be very large and would provide bioavailable iron for an area of many square kilometers. The particles according to the invention can be dispersed on a body of water, for example by releasing them or dispersing them from a ship or a cargo plane.

JH Martin has estimated, in Discover, pages 55-61 (April of 1991), that if about 3 x 108 kg (300,000 metric tons) of iron were scattered over the ocean surrounding the Antarctic during a growing season of 6 months , the resulting phytoplankton would convert 2 x 1012 kg of carbon derived from about 7.4 x 1012 kg of atmospheric carbon dioxide into new organic matter. This is about one third of the volume of C02 generated annually from all automotive sources and global thermoelectric plants. Thus, by means of the present invention, it is possible to significantly improve, if not completely cancel, the current levels of carbon dioxide introduced by man into the atmosphere. Suitable polymeric waterborne foam materials include, but are not limited to, foams made of polystyrene, polyurethane, polyester, polyvinyl alcohol, urea / formaldehyde, poly (lactides), and the like. These foam materials must be finely divided to have an increased surface area, and a subsequent faster degradation in use. A preferred micronutrient, as indicated above, is iron. Suitable sources of iron include, but are not limited to, inexpensive, ferrous or ferrous compounds such as elemental iron, ferrous sulfate, ferrous ammonium sulfate, ferric sulfate., ferrous chloride, ferric chloride, ferric nitrate, ferrous nitrate, iron oxides, iron hydroxides, iron suboxides such as oxychlorides, and mixed metal oxides containing iron such as phosphates, silicates, aluminates, aluminosilicates, and iron titanates . Iron of the Fe (III) form and in particular the Fe (III) hydroxy species is preferred. Water-soluble agents suitable for improving the adhesion of nutrient compounds to the substrate floating in the water include, but are not limited to, water-soluble organic polymers such as polyvinyl alcohol, poly (acrylic acid), poly (methacrylic acid), methylcellulose, hydroxymethyl cellulose, poly (N-vinyl pyrrolidones), poly (acrylamide), poly (ethacrylamide), poly (ethylene oxide), gelatin, natural gums; and water-soluble inorganic polymers such as sodium poly (silicates). Natural gums include mucilaginous gums derived from guar, agar agar, carob and carrageenan. An aqueous dispersion of particles containing the micronutrient source can be dried, preferably in air, at elevated temperatures, for example, between about 20 ° C and 130 ° C or more. It will be recognized that, in the practice of the present process, the components of the compositions floating in the water can be added in different orders. Optionally, a water-soluble adhesion promoter can be added to the substrate floating in the water before, during, or after mixing with one or more micronutrient source compounds. The Applicant has found, however, that the impregnation of floating substrates with micronutrient source compounds occurs most efficiently when the materials are added in the order described herein. As shown in Example 3 below, for example, more iron was adhered to the substrate when the substrate and the micronutrient solution were completely mixed before the addition of an adhesion promoter than when the micronutrient solution was added after mixing. of the substrate and the adhesion promoter. Processes that involve an alternative order of addition, while less preferred, nevertheless fall within the scope of this invention. In a preferred embodiment of the process for preparing the material according to the present invention, the substrate is mixed and impregnated with a solution of micronutrient source compounds, followed by the addition of an aqueous base solution, such as sodium hydroxide or , preferably, sodium polysilicate, which precipitates the iron on or within the substrate. This procedure increases the amount of iron compounds that adhere durably and rest on the substrate. Water-soluble adhesion promoters can also be included in the base solution. Sodium polysilicates are preferred, because they serve both as a base and as an adhesion promoter. It is noted that recently prepared iron containing compositions can darken their color due to oxidative processes, particularly when ferrous compounds are used. Such oxidative processes, however, do not adversely affect the effectiveness of the invention. The particles according to the present invention suitably have a larger average length in the range from about 0.001 mm to 100 mm, provided that when the largest average dimension is greater than 10 mm, the largest average transverse dimension perpendicular to the Length can not be more than 10% of the largest average dimension. (This condition is equivalent to establishing that the average aspect ratio should be greater than 10, where the aspect ratio is defined as the length, that is, the largest dimension, divided by the largest transverse dimension perpendicular to the length ). This condition is directed to particles when they are in the form of fibers, including strip and filiform forms. Suitable fibrous materials would include, for example, esparto or excluded polymers. The particles, in one embodiment of the invention, have a larger average dimension in the range from 0.001 ram (1 miera) to 10 mm, preferably about 0.1 to 5 mm. Such particles, including powders, can have various shapes, for example spherical, spheroidal, thin-cake, rectangular, square, cylindrical, conical, or irregular shapes. The lower or upper limits for the concentration of micronutrients in the compositions according to the invention may vary, depending on the particular water body, the time of year, and the desired result. It will be understood that the nutrient requirements for photosynthesis are extremely small. The compositions will usually comprise at least about 0.01% by weight of elemental micronutrient, preferably at least about 1%, more preferably at least about 10%. A practical upper limit can be as high as about 90% by weight. Only nanomolar (10"9 M) concentrations of bioavailable iron need to be supplied, for example, in HNLC regions of the equatorial Pacific It has been estimated (KS Johnson et al., In Marine Chemistry 4_6, 319, 331 (1994)) that The biological requirements for iron in the equatorial Pacific, based on several factors, including the Fe: C ratio of oceanic plankton, is 0.2 pmol of Fe l-1 hr "1. A supply ratio of 0.01 pmole of Fe l "1 hr" 1 would, therefore, probably be insufficient for a desired or optimum growth, while a supply ratio of 25 pmol l "1 hr" 1 or more in the 10 The upper equatorial Pacific Ocean would probably be well in excess of biological requirements. The minimum and optimal requirements may differ in other areas, for example, the Antarctic. In any case, the particulate compositions of the present invention can typically provide, over a period of prolonged use, bioavailable iron very much in excess of the biological growth requirements over the target area. A relatively large area of ocean can be practically supplied with sufficient micronutrients by means of the present invention. The source of the micronutrient is released for a sustained period of time, to provide the requirement for biological growth, on average, for at least one week, more preferably at least 1 month, and more preferably for several months up to about a year or plus . The use of a substrate floating in the water is preferred. It has also been found, however, that the micronutrient source compounds, for example, iron compounds, can be converted into particles floating in the water without using a substrate floating in the separated water (see Examples IA, 6) . For example, one or more particulate iron compounds can be mixed and covered or encapsulated with a sealant, such as a solution of aqueous sodium poisilicate (or a mixture of polysilicate or basic hydroxide or carbonate with a water-soluble polymer), followed by by drying. An example of hydroxide is sodium hydroxide. Examples of carbonates include sodium carbonate or calcium carbonate. Alternatively (as in Example 6), an aqueous mixture of iron and polysilicate compounds, optionally also containing an alkali metal carbonate, alkaline earth metal carbonate, or alkali metal bicarbonate, after drying to remove most of the water, can be converted to floating particles by heating at a high temperature (for example, with a Mekker oven). The composition of the present invention is useful for promoting the photosynthetic growth of a wide variety of phytoplankton, including, but not limited to, diatoms, coccolithophorids, choanoflagellates, pico-eukaryotes, cyanobacteria, prochlorophytes, and autotrophic dinoflagellates, for example, Synechocystis, Dunaliella tertiolecta, Synechococcus, Spherocalyptra papillifera, Emiliana huxleyi, Nitzschia sp., Chaetoceros atlanticus, Mediterranean Meringosphaera, to name just a few. By increasing the growth of phytoplankton it can, in turn, contribute to the growth of another parallel biomass in the food chain. For example, phytoplankton support vast crowds of krill and other marine creatures that are food for various fish, as well as seals, penguins, and whales. The following examples are illustrative of the invention, but by no means limiting thereof. The data presented in Tables 1 and 2 below show that the particulate compositions floating in the water and carrying micronutrients of the invention are effective stimulants for the growth of photosynthetic phytoplankton in both environments, fresh water and seawater for periods of days, and that the compositions have no adverse effects on growth in normal, iron-containing medium. General Procedure to Test the Efficacy of Compositions that Float in Water and Contain Iron as Sources of Micronutrients The freshwater cyanobacterium, Synechocystis PCC6803 (from the collection of cyanobacterial cultures of the Pasteur Institute, Paris, France) was cultivated, and the green seaweed (from seawater) Dunaliella tertiolecta on their respective culture media BG-II and artificial seawater (ASW), described below, except that both media were devoid of iron. The cultures were serially diluted until they were growing clearly more slowly than their counterparts in normal culture medium BG-II and ASW containing the iron nutrient. The iron-depleted cells were then used to inoculate both the iron-depleted and the normal iron-containing media, as described below. Both sets of inoculated media were then exposed to the iron-impregnated compositions that floated in the water of the invention, and were studied in comparison to controls that were not exposed to the compositions. Various compositions of the invention were placed in tubes (100 mm x 11.5 mm internal diameter) in a weight in the range of 0.1-1.0 mg, and inoculated with iron-depleted or normal cultures, fed with iron, prepared as described up, to a total volume of 2. 5 ml. The tubes were made of glass (Synechocystis) or plastic (Dunaliella). The cells were cultured by placing the tubes on a rotating wheel, to allow mixing and aeration of the cultures, and they were illuminated uniformly in the fluorescent light at 10-20 w / mZ. The tubes were kept ° C, and the growth ratios were followed by the optical density measurement at 730 nm. Liquid BG-II: An enriched freshwater growth medium prepared according to R. Rippka et al., J.

Gen. Microbiol., 111-1 (1979): N-Tris (hydroxymethyl) methyl-2-aminoethane sulfonic acid-1M KOH, pH 8.2, 5 ml; BG-FPC *, 10 ml; Ammoniacal ferric citrate, 6 mg (suppressed from the iron-deficient medium); Sodium carbonate, 20 mg; monohydrogen and potassium phosphate, 30.5 mg; water, to a total of 1 1. Autoclave for 45 minutes; a precipitate forms which is resuspended by agitation. When a nutrient supplement is required, 5 ml / 1 of 1 M glucose solution is added. * BG-FPC: NaN03, 149.58 g / 1; MgSO4.7H20, 7.49 g / 1; CaCl2.2H20, 3.60 g / 1; Citric acid, 0.60 g / 1; NaEDTA pH 8.0, 0.25 M, 1.12 ml; or EDTA pH 7.5, 0.2 M, 1.40 ml; Trace Minerals (clear) **, 100 ml; H20, to 1 liter; ** Trace Minerals: H.BOs, 2.8 g / 1; MnCl2.4H20, 1.81 g / 1; ZnS04.7H20, 0.22 g / 1; Na2Mo0 .2H20, 0.390 g / 1; CuS04.5H20, 0.079 g / 1; C? (N03) 2.6H20, 0.0494 g / 1; H 0, to 1 liter.

Artificial Seawater: The following composition of artificial seawater (ASW) was prepared according to Goldman et al., Limnol. & Oceanogr., 23, 695 (1978); McLachlan, Can. J. Microbiol., 10, 769 (1964): NaCl, 23.4 g; MgSO4.7H20, 4.9 g / 1; CaCl2.2H20, 1.11 g / 1; KBr, 0.2 g; KC1, 0.75 g; MgCl2.6H20, 4.1 g; NaN03, 0.075 g; Mixture of vitamins *, 4 ml of secondary standard Tris- (hydroxymethyl) aminomethane, 1 ml of standard solution ** Trace metals * * * (not iron), 1 ml of standard solution; NaH2P04. H20, 5 g; Selenious acid, 1 ml of 10 μM solution Distilled water to 1 liter. * Mixture of vitamins: Primary standard: Biotin (dissolved in 1 drop / mg of 0.1 N NaOH), 10 mg in 10 ml of distilled water; B: 2, 10 mg in 10 ml of distilled water. Secondary pattern: 1 ml of each of the primary biotin and Bi2 standards; 900 ml of distilled water; Thiamin HCl, 200 mg; Distilled water to 1 liter. ** Standard solution of Tris- (hydroxymethyl) aminomethane: Tris- (hydroxymethyl) amyromethane, 50 g; 10 M HCl, 20-30 ml; adjust the pH to 7.1-7.3; Distilled water to 200 ml. *** Metals Traces: CuS0 .5H20, 980 mg; ZnS04.7H20, 2.2 g; CoCl2.6H20, 1.0 g; MnCl2.4H20, 18.0 g; Na2Mo04.2H20, 630 mg; Distilled water to 100 ml. For artificial sea water containing iron, 4 ml of a standard solution containing 0.186 g of Na2EDTA and 0.135 g of FeCl3.6H20 per liter in the composition of artificial seawater were included.

In the Examples, the percentages are by weight, and the temperatures are in degrees Celsius, unless otherwise indicated. EXAMPLE 1 ÍA. A solution of 5 g of ferrous chloride (FeCl2.4H20) in 25 ml of water containing 2.5 g of Elvanol ™ 50-42 polyvinyl alcohol from Du Pont was added to a solution of 10 g of sodium poisilicate (Na20. 2.6 Si02, 14% NaOH, 27% SiO2) in 20 ml of water. A dark green precipitate was obtained, which turned black slowly, by oxidation. After 5 hours, a few particles of the precipitate were dried. When the dried particles were re-introduced into water, they floated, and the particles remained intact after floating in still water for more than a month. This experiment shows that a separate floating substrate is not necessary. However, the performance of floating particles in which the source of micronutrient is originally incorporated into the substrate is small, compared to the amounts of particulate substrates that are separately available for use in the present invention. IB. Example IA was repeated, except that 0.4 g of hollow glass particles (ECCOMR spheres); Emerson & Cumming, Inc., Type TF-15) were placed in the initial solution of ferrous ride / polyvinyl alcohol. After the addition of the sodium polysilicate solution, as above, a similar precipitate was obtained, most of which adhered to the floating glass particles. After drying, the dark colored coated particles floated on the water, and retained their integrity after at least one month in water. When Example IB was repeated except that the polyvinyl alcohol was removed, the oxidized and dried particles remained floating but slowly disintegrated in the water. EXAMPLE 2 2A. Five ml of a solution consisting of 15 g of FeSO4.7HrO and 75 ml of 2% aqueous poly (acrylic acid) by weight (molecular weight 2,000,000) in 75 ml of water were mixed vigorously with a suspension of 5 ml of particles of hollow glass ECCO ™ in 20 ml of 20% aqueous sodium polysilicate (Na20.2.6Si02, 14% NaOH, 27% SiO :). The iron-containing compounds precipitated, and much of it adhered to the glass particles. The precipitate was initially dark green, and slowly turned black due to oxidation. After standing for 5 minutes, the mixture was diluted to 118 ml in a round bottle. Essentially all the solids floated; only traces of the solids settled. The bottle was placed on rotating rolls, and rotated at 2 rev / second for 30 hours. The highly colored iron compounds remained floating even after a week of turning, with only a trace of sediment. 2B. Example 2A was repeated, except that the poly (acrylic acid) solution was replaced with a 1% aqueous solution by weight of methyl cellulose. A finely divided precipitate was obtained, which adhered mostly to the floating glass particles. However, when the mixture was rotated for 30 hours as described in Example 2A, the insoluble iron compounds were released from the floating glass particles and settled to the bottom of the bottle. This illustrates the controllable separation of the iron compounds from the floating glass particles. 2 C. When either the poly (acrylic acid) of Example 2A or the methyl cellulose of Example 2B were omitted, most of the iron-containing solids were pelleted to the bottom of the bottle. The glass particles were stained yellow-green, indicating that some of the iron compounds were still adhered to them. 2D Example 2A was repeated, except that the poly (acrylic acid) was replaced with a 10% aqueous solution by weight of Elvanol ™ 50-42 polyvinyl alcohol, and the hollow glass particles were added directly (without polysilicate solution). of sodium) to the ferrous sulphate / polyvinyl alcohol mixture. The iron compounds precipitated, and much of the precipitate remained adhered to the glass particles. After stirring, a 20% sodium polysilicate solution was added. Most of the iron compounds remained attached to the floating particles, but a significant amount of iron-containing material that did not float was present as sediment. After turning in water in a round bottle for one day, followed by rest for a month, approximately the same amount of iron-containing material remained attached to the floating particles. EXAMPLE 3 This example illustrates how the order in which the ingredients are mixed affects the ability to float of the precipitated iron-containing compounds. 3A. A suspension of 10 ml of hollow glass particles (PQ Extendospheres ™ ash powder) in 20 ml of water and 5 ml of 0.84 M aqueous ferric chloride was stirred in a round bottle and subjected to aging for 5 minutes. Then 3 ml of sodium polysilicate solution ((Na20.2.6Si02, 14% NaOH, 27% SiO £) was added, and the mixture was stirred and diluted to 100 ml with water. solids were floating, the precipitated iron compounds remained attached to the floating glass spheres, 3B a suspension of 10 ml of hollow glass particles (PQ Extendospheres ™) in 20 ml of water and 3 ml of sodium polysilicate solution (( Na20.2.6 Si02, 14% NaOH, 27% Si02) was stirred in a round bottle, and subjected to aging for 5 minutes, then 5 ml of 0.84 M aqueous ferric chloride solution was added, and the mixture was stirred and diluted to 100 ml with water.After one hour, a large portion of the precipitated iron-containing compounds settled to the bottom.The floating hollow particles were mostly free of iron compounds.The same results were obtained when the spheres of ECCOMR replaced n by Extendospheres'R particles, EXAMPLE 4 This example illustrates the use of a polymeric foam to make the iron compounds float. Since the polymer is designed to degrade oxidatively when exposed to sunlight and air; the degradation rate will be increased by using smaller foam particles with a larger surface area. Polystyrene foam (peanut-shaped) packaging material was reduced to a particle size of about 1-5 mm in a food mixer. The particles initially were water repellent, but became wet when shaken with water. They remained floating in water and insoluble. 4A. Polystyrene foam particles, prepared as described above, were stirred with a 10% ferric chloride solution in water, until the particles were coated with the solution. After drying at 90 ° C in air, the coated particles were dark brown, and floated. The soluble iron salts were slowly released from the floating foam particles. It is believed that the brown color owes to the formation of ferric oxychlorides, some of which are partially soluble, and to the gradual hydrolysis of the oxychlorides to insoluble ferric oxide. It is expected that the long-term photo-oxidative degradation of the polymer will occur, and the gradual release of the iron oxides on the surface of the water. 4B. The 4A Experiment was repeated, except that the iron-coated polystyrene particles were treated with 5% aqueous sodium hydroxide after drying, to rapidly convert the ferric oxychlorides to ferric oxide, with an increasing dark brown coloration. The particles were floating, apart from a smaller amount of brown ferric oxide sediment. 4C. Experiment 4B was repeated, except that the sodium hydroxide was replaced with sodium polysilicate ((Na20.2.6 SiO2, 14% NaOH, 27% Si02), the floating foam particles were dark brown, and a minimum amount of iron and silica sediments was present 4D Experiment 4A was repeated, except that the palstyrene was replaced with PQ Extendospheres ™ particles (hollow glass particles) An exactly sufficient amount of 10% aqueous ferric chloride solution was used To moisten the particles, which were then dried at 110 ° C. Some of the particles coated with ferric chloride were melted, but were easily separated by gentle scraping.The coated particles floated on water, and retained most of their coating; and only a trace of iron precipitated.

When treated with sodium hydroxide as in Experiment 4B, the spheres remained coated with precipitated iron compounds, but the amount of precipitate of unbound precipitated iron was increased. A similar result was obtained using sodium polysilicate instead of sodium hydroxide. EXAMPLE 5 In this example, the polystyrene foam particles had their pores filled with powdered ferric oxide and, except in experiment 5A, they were coated with an adhesion promoter. 5A. Ten ml of water, 0.2 g of powdered polystyrene foam and 1 g of ferric oxide powder were mixed, and the excess water was removed. The mixture was dried at 60 ° C. Some of the dry mixture was mixed again with water and stirred. Much of the red ferric oxide sedimented as sediment, but the porous, floating, red colored polymer particles retained a substantial amount of the ferric oxide. 5B. Experiment 5A was repeated, except that the initial water also contained 1 g of sodium polysilicate solution (Na20.2.6 SiO2, 14% NaOH, 27% Si02). Part of the red ferric oxide was separated by sedimentation, part was attached to the polystyrene foam particles as in 5A, but in this case, some ferric oxide was also dispersed in the liquid phase. 5C. Experiment 5B was repeated, except that the sodium polysilicate was replaced with polyvinyl alcohol (5 ml of water, 5 ml of Elvanol® 50-42 5%). The results were similar to those of experiment 4B, in that ferric oxide was present on the foam particles, dispersed in the liquid, and in the sediment. 5 D. Experiment 5B was repeated except that poly (vinyl alcohol) (5 ml of water, 5 ml of Elvanol® 50-42 5%) was also added, as well as sodium poisilicate. The results were very similar to those of Experiment 5C. 5E. Floating material from each of the above experiments was placed in individual round bottles, and water was added. The four bottles were then placed on rollers, and rotated for 22 hours. After rotation, the foam particles in each bottle had partially disintegrated, and they had released some iron oxide, which had dispersed in the aqueous phase. There was no subsequent change after resting one month.

EXAMPLE 6 In this example, a solid mixture of sodium polysilicate and ferric oxide was converted into a low density, particulate and floating glass composition. Twenty grams of ferric oxide powder (red, anhydrous, from Fischer Scientific) and 150 g of sodium silicate (Aldrich; Na20.2.6Si02, in water) were mixed in a food mixer until a uniform dispersion was obtained. The dispersion was poured into a crystallization disk, and dried in an oven at 120 ° C. During drying, a hard, rubber-like crust was initially formed around each particle, the particles then gradually turned into hard, dark red vitreous particles. When a portion was heated with a Mekker burner, the small particles melted and formed fragile, hollow, low density particles that floated on water and slowly released ferric oxide particles. After one week in the presence of water without agitation, many iron-containing particles remained floating, some iron oxide had settled, and another iron-containing material dispersed in the water, as if it had been saponified.

By heating the dry mixture in a warmer, propane / oxygen flame, further melting and eventual loss of the hollow particles was caused; and some reduction of ferric oxide was also observed. EXAMPLE 7 In this example, a floating polyurethane foam was used to make a floating, low density particulate composition containing ferric oxide. Ferric oxide (2 g) was ground to a uniform suspension in 2 ml (2.55 g) of the glycerin / resin used to make INSTAPAKMR polyurethane foam commonly used in packaging to deliver fragile articles. This uniform suspension was rapidly mixed for 40 seconds at room temperature with 2 ml (2.44 g) of the polymeric isocyanate (diphenylmethyl isocyanate) used in the INSTAPAK ™ system. The mixture formed a brittle red porous structure. 7A. In Test A, a cubic-shaped piece of approximately 1 cm of the ferric oxide / polyurethane foam was placed in quiescent water in a flask at room temperature. The piece settled slowly in the water, until it just floated. After 1 week, only a few red particles had separated, and sank to the bottom of the bottle. The mass of the foam sample remained floating. 7B. In Test B, the procedure of Test A was followed, except that the water and several 1 cm pieces of ferric oxide / polyurethane compound were placed in a narrow neck bottle of 113.4 g (4 ounces), which sealed and placed on rotating rollers to rotate for a week at room temperature. Only a few small particles separated, and about two-thirds of them sank. This showed that, in stirred water, the porous compound slowly releases small particles of ferric oxide, which will provide bioavailable iron for photosynthesis. 7C. In Test C, part of the original ferric oxide / polyurethane foam was ground in a food mixer, and the powder was placed in water. Initially, most of the dust particles floated, but after 3 hours, the smaller particles had sunk. After 1 week, about 2/3 of the particles had sunk. EXAMPLE 8 In this Example, a floating polyurethane foam containing iron was prepared, as in Example 7, except that the ferric oxide was replaced with ferric chloride (FeCl: .4H20; 1 g). After the ingredients were mixed together, a very dense foam developed slowly during the night. The foam floated on water, and the iron ions were slowly leached into the water. After 4 days, the foam remained floating, and had a yellow color, indicating the continuous presence of iron in the foam. The foam must be divided into particles before using it. EXAMPLE 9 This example illustrates the preparation and use of a floating polyurethane foam composition containing ferric phosphate to stimulate photosynthetic growth in iron deficient seawater and freshwater. A 0.5 M solution of trisodium phosphate was prepared (NajP0) dissolving 13.4 g (0.05 mole) of hydrogen phosphate and disodium (Na2HP04.7H20) in 70 ml of water, then adding 2.0 g (0.05 mole) of sodium hydroxide to the solution, followed by dilution to 100 ml with Water. Forty milliliters of the trisodium phosphate solution was mixed with 40 ml of a 0.5 M aqueous solution of ferric chloride. The mixture was stirred, and the precipitated ferric phosphate was filtered off, washed with water, methanol and finally methylene chloride. Yield: 2.86 g (92%) of FeP0 as a pale yellow powder.

INSULATURAL PHOSPHATE FIBER (1.5 g) was mixed with 3.2 g of INSTAPAK ™ 40W polyethylene foam / resin glycerin component B (from Complete Packaging, Inc.) in a mortar and ground into a paste. Three grams of the isocyanate component C of the foam ingredients were added to the mortar and mixed rapidly with a pistil. After 3 minutes, a pale yellow, open-pored, dry foam had formed, which occupied about 150 ml. The foam (31-F) weighed 7.5 g, and was found to contain about 20% FeP04. One gram of 31-F was ground in a mixer, then stirred with deionized water for 1 day. The foam was separated by filtration, then resuspended in water, allowed to stand for 5 days with occasional agitation. A small amount of solid matter settled. The floating material was carefully removed, and stored wet (31-W) until proven to be a source of micronutrient. The foam compositions floating on water 31-F and 31-W were proven as sources of micronutrients for photosynthetic growth in both artificial seawater and water medium BG-11, according to the general procedure described above. The results are given in Table 1 for the growth of Synechocystis in BG-11, and in Table 2 for Dunaliella in artificial seawater. The results show that with both photosynthetic organisms, the cells in the iron-depleted medium grow more slowly than those in medium supplemented with iron. After 3 days, the density of the cells was about 5 times higher for Synechocystis in Bg-11 which contained the foam compositions 31-F and 31-W compared to Synechocystis in BG-11 that did not contain iron supplementation. After 3 days, the cell density was about 4 times higher for Dunaliella in artificial seawater containing the foam compositions 31-F and 31-W compared to Dunaliella in artificial seawater that did not contain iron supplement. When the iron-depleted medium was seeded with 31-F and 31-W, the cell growth accelerated to a point where it approached that of the normal medium, supplemented with iron, that is, after 3 days of growth, the Cell density was 3-4 times higher than iron depleted control. EXAMPLE 10 Particulate polystyrene foam compositions (1.2 g) were placed on a glass disk, and 10% aqueous ferric chloride solution was added by weight in small amounts, until the foam particles were wet. The disc was covered without cohesion with aluminum foil, and dried at 90 ° C for 3 days. The dry foam composition contained 2.0 g of iron compound, which was believed to be mostly ferric oxychloride. The particulate foam composition was suspended in water for 1 day, filtered, washed with water, then soaked in fresh water for 5 days. The floating material was collected and dried. The particles varied in color from whitish (large particles) to tan (smaller particles, 32-A). Composition 32-A was tested as a source of micronutrients for photosynthetic growth in both media, sea water and fresh water, according to the general procedure described above. The results are given in Table 1 for the growth of Synechocystis in Bg-11 and in Table 2 for Dunaliella in artificial seawater. The results show that with both photosynthetic organisms, the cells in the medium supplemented with iron grew more rapidly than those in iron-depleted medium. After 3 days, the cell density was 4-5 times higher in the presence of the 32-A foam composition than in the iron-depleted medium, as in Example 9.

EXAMPLE 11 Hollow glass spheres (PQ ExtendospheresH ?, of ash dust) were impregnated with ferric oxychloride, mixing 5 g of the spheres, 1 g of ferric chloride and 10 ml of water. The mixture was heated to 140 ° C in air, in an oven for 1 hour, then cooled. Water (200 ml) was added, and the suspension was allowed to stand overnight. An upper layer was decanted. The remainder was filtered, suspended in water for 2 hours, filtered and dried. The recovered product weighed 4 g. The product (36) was passed through a 60 mesh screen. Under a microscope, the spheres were lined with a red deposit; some conglomerates of 2 or 3 spheres were present. The composition 36 was tested as a source of micronutrient floating in the water, together with the products of Examples 9 and 10, to determine the photosynthetic growth in both media, of sea water and fresh water, according to the general procedure described above. The results are given in Table 1 for the growth of Synechocystis in Bg-11 and in Table 2 for Dunaliella in artificial seawater. The results show that with both photosynthetic organisms, the cells in the medium supplemented with iron grew more rapidly than those in iron-depleted medium.

After 3 days, the cell density was 4-5 times higher in the presence of the 32-A foam composition than in the iron-depleted medium, as in Examples 9 and .

TABLE 1 Growth of Synechocystis PCC6803 in BG-11 Medium Sample Description Optical Density (730 nm) 0 hr 21.25 hr 46.67 hr 73.5 hr 0 E 0.104 0.21 0.34 0.45 1 E + 0.1 mg of 31-W 0.104 0.22 0.35 0.53 2 E + 0.1 mg of 31-F 0.103 0.22 0.33 0.58 3 E + 0.1 mg of 32-A 0.105 0.21 0.42 0.82 4 E + 0.1 mg of 36 0.106 0.23 0.66 1.25 5 E + 1.0 mg of 31-W 0.104 0.21 0.33 0.56 6 E + 1.0 mg of 31-F 0.106 0.31 0.59 1.88 7 E + 1.0 mg 32-A 0.105 0.26 0.61 1.49 8 E + 1.0 mg of 36 0.105 0.33 1.01 2.05 9 G 0.107 0.40 1.18 2.54 10 G + 0.1 mg of 31-W 0.109 0.30 1.20 2.63 11 G + 0.1 mg of 31-F 0.107 0.41 1.11 2.41 12 G + 0.1 mg of 32-A 0.108 0.41 1.07 2.39 13 G + 0.1 mg of 36 0.109 0.39 1.16 2.51 14 G + 1.0 mg of 31-W 0.107 0.42 1.11 2.39 15 G + 1.0 mg of 31-F 0.110 0.41 1.13 2.47 16 G + 1.0 mg 32-A 0.110 0.40 0.98 2.48 17 G + 1.0 mg of 36 0.111 0.41 1.18 2.80 18 H 0.112 0.61 1.44 2.94 E = Cells that grew in the absence of Fe and were inoculated in Fe-free medium; G = Cells that grew in the absence of Fe but were inoculated in normal medium, which contained Fe; H = Cells that grew in the presence of normal amounts of Fe and were inoculated in normal medium containing Fe.

TABLE 2 Dunaliella tertolecta growth in Artificial Seawater Sample Description Optical Density (730 nm) 0 hr 21.25 hr 46.67 hr 73.5 hr 0 E 0.125 0.216 0.285 0.340 1 E + 0.1 mg of 31-W 0.114 0.247 0.725 1.05 2 E + 0.1 mg of 31-F 0.118 0.243 0.616 1.12 3 E + 0.1 mg of 32-A 0.118 0.228 0.402 0.62 4 E + 0.1 mg of 36 0.121 0.270 0.616 1.09 E + 1.0 mg of 31-W 0.111 0.234 0.558 1.10 6 E + 1.0 mg of 31-F 0.122 0.206 0.60 1.14 7 E + 1.0 mg 32-A 0.116 0.202 0.484 0.975 8 E + 1.0 mg of 36 0.116 0.232 0.436 1.10 9 G 0.128 0.254 0.636 1.38 10 G + 0.1 mg of 31-W 0.093 0.238 0.628 1.2 11 G + 0.1 mg of 31-F 0.117 0.240 0.605 1.2 12 G + 0.1 mg of 32-A 0.112 0.234 0.60 1.2 13 G + 0.1 mg of 36 0.122 0.277 0.508 1.0 14 G + 1.0 mg of 31-W 0.10 0.178 0.432 0.935 15 G + 1.0 mg of 31-F 0.116 0.116 0.314 0.86 16 G + 1.0 mg 32-A 0.107 0.164 0.374 0.795 17 G + 1.0 mg of 36 0.113 0.234 0.574 1.14 18 H 0.089 0.245 0.632 1.2 E = Cells that grew in the absence of Fe and were inoculated in Fe-free medium; G = Cells that grew in the absence of Fe but were inoculated in normal medium, which contained Fe; H = Cells that grew in the presence of normal amounts of Fe and were inoculated in normal medium containing Fe.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following:

Claims (27)

1. CLAIMS 1. A composition, characterized in that it comprises particles that float in water, ranging from about 0.01% to 90% by weight of elemental micronutrients for the photosynthetic growth of phytoplankton, the particles have a larger average dimension in the range from about 0.001 mm to 100 mm, provided that when the largest average dimension is greater than 10 mm, the largest average transverse dimension perpendicular to the length can not be more than 10 a of the larger average dimension. The composition according to claim 1, characterized in that the elemental micronutrient is selected from the group consisting of Fe, Co, Mn, Zn, and mixtures thereof. 3. The composition in accordance with the claim 1, characterized in that it additionally comprises a particulate substrate material floating in the water, chemically inert, relatively insoluble in water, which supports a micronutrient source. 4. The composition in accordance with the claim 2, characterized because the elemental micronutrient is iron. 5. The composition according to claim 3, characterized in that the composition comprises a substrate of floating particles in the water, made of a polymeric foam, hollow glass, or cellulose. The composition according to claim 5, characterized in that the polymer comprising the polymeric foam is selected from the group consisting of polystyrene, polyurethane, polyester, polyvinyl alcohol, poly (lactide), and urea / formaldehyde. The composition according to claim 5, characterized in that the hollow glass particles are derived from ash dust. The composition according to claim 3, characterized in that it additionally comprises at least one water soluble agent to effect or promote adhesion of the micronutrient source to the substrate and / or to delay its release from the source of micronutrients to a body of water that surrounds it during its use. The composition according to claim 8, characterized in that the water-soluble agent for promoting adhesion of the micronutrient source to the substrate is selected from the group consisting of polyvinyl alcohol, poly (acrylic acid), poly (methacrylic acid), methyl cellulose, poly (N-vinyl pyrrolidine), poly (acrylamide), poly (ethacrylamide), poly (ethylene oxide), gelatin, natural gum, and sodium polysilicate. 10. The composition according to claim 2, characterized in that it contains at least about 1% elemental micronutrient. 11. The composition according to claim 10, characterized in that the elemental micronutrient is iron. The composition according to claim 11, characterized in that the source of micronutrient is selected from the group consisting of elemental iron, ferrous sulfate, ferrous ammonium sulfate, ferrous chloride, ferric chloride, ferric nitrate, ferrous nitrate, iron oxides , mixed metal oxides comprising iron, iron hydroxides, iron suboxides, oxyhalides, and mixtures thereof. 13. A dry, particulate composition according to claim 2 or 3. 14. An aqueous dispersion of the composition according to claim 2 or 3. 15. The composition according to claim 13 or 14, characterized in that it is in an amount of at least one metric ton. 16. Process for preparing an aqueous dispersion of a composition comprising particles that float in water containing about 0.1% to 90% by weight of a micronutrient for photosynthetic growth of phytoplankton selected from the group consisting of Fe, Co, Mn, Zn , and mixtures thereof, the particles have a larger average dimension in the range from 0.001 mm to 100 mm, provided that when the largest average dimension is greater than 10 mm, the largest transverse average dimension perpendicular to the length can not be more than 10% of the largest average dimension, the process is characterized in that it comprises mixing and impregnating a particulate substrate material that floats in water, relatively insoluble in water with an aqueous solution or dispersion of one or more compounds that are a source of the micronutrient. Process according to claim 16, characterized in that it additionally comprises drying the aqueous dispersion of the composition, to provide free flowing particles. Process according to claim 17, characterized in that the solution or dispersion containing the micronutrient source also contains one or more water-soluble agents, which promotes the durable adhesion of the source compound of the micronutrient to the substrate. Process according to claim 17, characterized in that it additionally comprises the application of one or more water-soluble agents that promote the durable adhesion of the source compound of the micronutrient to the substrate. 20. Process to stimulate the photosynthetic growth of phytoplankton in an ocean, lake, or river devoid of, or deficient in, such growth, the process is characterized in that it comprises supplying iron to the surface the areas of the ocean, lake, or river deploying particles that float in water that contain about 0.01% to 90% by weight of iron on the surface of the ocean, lake or river, the particles have a larger average dimension in the range from about 0.001 mm to 100 mm, always that when the largest average dimension is greater than 10 mm, the largest average transverse dimension perpendicular to the length can not be more than 10 ° of the larger average dimension. 21. Process according to claim 22, characterized in that the ocean, lake, or river is an ocean. 22. Process according to claim 21, characterized in that the global carbon dioxide is reduced by the generation stimulated by iron of photosynthetic oceanic phytoplankton. 23. Process according to claim 20, characterized in that the marine or freshwater food is increased by the generation stimulated by photosynthetic phytoplankton iron. 24. Process for preparing a particulate composition, which floats in water, containing about 0.01% to 90% by weight of a micronutrient for photosynthetic growth of phytoplankton selected from the group consisting of Fe, Co, Mn, Zn, and mixtures thereof, the process is characterized in that it comprises the following steps: (a) obtaining particles from an insoluble source of micronutrients in an aqueous medium, containing a soluble sealing agent by either of (i) mixing particles from an insoluble source of micronutrients in an aqueous medium containing a soluble sealing agent, or (ii) precipitating a soluble source of micronutrient from an aqueous medium containing a soluble sealing agent; and (b) drying the mixture of (a) and, if step (a) (i) was previously carried out, then further melting the particles at a temperature of at least about 1000 ° C, formed with this particles that They float in the water, free flowing, coated with the sealing agent, to temporarily seal the surfaces of the particles. Process according to claim 24, characterized in that the source of the micronutrient is elemental iron or a compound thereof. Process according to claim 24, characterized in that the soluble source of the micronutrient in step (a) is precipitated by adding a base or alkali. Process according to claim 12, characterized in that the source of the micronutrient is a mixed oxide of metal, containing iron, selected from the group consisting of iron phosphates, iron silicates, iron aluminates, iron aluminosilicates and titanates of iron.