Fertilizer materials, iron ion supply method, and seaweed bed creation method

Abstract

The objective is to provide a fertilizer that enables both the leaching and diffusion of iron humate from the fertilizer, regardless of the dissolved oxygen environment in the surrounding area where the fertilizer is installed. [Solution] The solution comprises a fabric material 3 and an iron ion supplying fertilizer material 2 covered on the fabric material 3, wherein the permeability coefficient of the fabric material 3 is 6.00 × 10 ―3 cm / sec or more, 4.60×10 ―2 Fertilizer material 1 with a flow rate of cm / sec or less will be used.

Description

[Technical Field]

[0001] The present invention relates to a fertilizer material installed in aquatic areas, particularly marine areas, in which an iron ion supplying fertilizer material that provides nutrients to algae and microorganisms growing in the aquatic area is covered with a cloth material, as well as a method for supplying iron ions and a method for creating seaweed beds using this fertilizer material. [Background technology]

[0002] In recent years, a decline in biological productivity due to a lack of iron, which is essential for the growth of organisms, has become a problem in aquatic environments such as marine, freshwater, and brackish water areas. For example, along the coasts of various sea areas throughout Japan, a phenomenon called "isoyake" has occurred, where seaweed can no longer grow on rocky areas and are covered with calcareous algae, resulting in a decrease in kelp, wakame, and many other types of seaweed communities and leaving them barren.

[0003] In addition to environmental changes such as rising seawater temperatures and water pollution, one possible cause of this coastal barrenness is that the felling of trees in the upper reaches of rivers flowing into the sea has made it more difficult for iron humate to form, which was previously formed by the combination of humic acid in humus soil and iron in the soil. This has reduced the supply of iron necessary for algal growth to the sea.

[0004] To address these problems, a method of protecting the aquatic environment has been known that involves installing aquatic environment protection materials, such as steel slag containing divalent iron and humic acid containing substances, in marine areas (Patent Document 1).

[0005] Furthermore, a method for preserving the aquatic environment is known in which a container for preserving the aquatic environment is installed near a block body for seaweed bed creation, the container being a hard container with an open top or a hard container having one or more holes, containing a fertilizer material that contains steel slag, or a permeable bag filled with this fertilizer material (Patent Document 2).

[0006] Furthermore, a method is known for sinking a water environment conservation container body to the seabed, which comprises a bottom surface, a top surface, and side walls that serve as the installation surface, and contains a fertilizer material containing steel slag, or a permeable bag filled with this fertilizer material, wherein the top surface and bottom surface have multiple openings formed therein for supplying nutrients from the fertilizer material, the ratio of the total area of ​​the openings to the total area of ​​the top surface, bottom surface, and side walls is 0.2 to 2.0%, and the ratio of the area of ​​the openings formed on the bottom surface to the total area of ​​the openings formed in the entire container is 30 to 50% (Patent Document 3).

[0007] According to these methods, divalent iron in steelmaking slag combines with fulvic acid and organic complexes, which are humic acid-containing substances, to form stable iron humate such as iron fulvic acid, and the diffusion of iron humate makes it possible to efficiently supply divalent iron ions to aquatic bodies. In other words, normally, divalent iron ions (Fe) that can be ingested by living organisms 2+ Even if iron is dissolved, it is immediately oxidized by dissolved oxygen in seawater and settles as solid iron (Fe2O3, Fe(OH)3), making it impossible for organisms to ingest it. However, by using the aquatic environment conservation materials mentioned above, it is possible to stably supply iron as iron humate. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2006-212036 [Patent Document 2] Japanese Patent Publication No. 2007-330254 [Patent Document 3] Japanese Patent Publication No. 2013-236571 [Overview of the project] [Problems that the invention aims to solve]

[0009] Incidentally, in order to stably leach humic iron, such as fulvic iron, from fertilizers such as aquatic environment conservation materials or aquatic environment conservation containers, it is effective to reduce oxidation by dissolved oxygen, that is, to place the fertilizer in an anaerobic environment.

[0010] However, the aquatic environment conservation method described in Patent Document 1 does not consider specific construction methods for maintaining an anaerobic environment for the installation of fertilizer materials (aquatic environment conservation materials).

[0011] Furthermore, Patent Document 3 describes how, in order to make the internal environment of the fertilizer material (aquatic environment conservation container) anaerobic with a reduced amount of dissolved oxygen, the opening ratio of the container is determined so that the amount of dissolved oxygen flowing into the aquatic environment conservation container by water flow does not exceed the amount of dissolved oxygen consumed inside the aquatic environment conservation container.

[0012] However, generally speaking, the greater the concentration gradient at the solid-liquid interface of a substance, the greater the amount of substance leached from the solid by diffusion. Therefore, for a fertilizer to exert its iron-leaching effect, it is important that the seawater inside the fertilizer is sufficiently replaced. If the inflow of seawater into the container is simply restricted to reproduce anaerobic conditions, as shown in Patent Document 3, iron ions may accumulate inside the container and not diffuse sufficiently into the seawater. Furthermore, as in the method described in Patent Document 3, simply providing an opening in the container results in an uneven distribution of seawater flowing into the container. This leads to an uneven distribution of dissolved oxygen within the container and the diffusion of fertilizer components to the outside, resulting in the problem that the fertilizer's effect is not fully realized.

[0013] The present invention aims to provide a fertilizer, an iron ion supply method, and a seaweed bed creation method that enable the simultaneous elution and diffusion of iron humate from the fertilizer, regardless of the dissolved oxygen environment in the surrounding area where the fertilizer is installed. [Means for solving the problem]

[0014] As a result of intensive studies conducted by the present inventors to solve the above problem, the present inventors have found that by coating a cloth material with an iron ion-supplying fertilizer, both delayed oxidation of ferrous iron inside the iron ion-supplying fertilizer and diffusion of ferrous iron to the outside can be achieved at the same time, so that iron humate can be eluted stably, and thus completed the present invention. That is, the gist of the present invention is as follows.

[0015] [1] A cloth material, and an iron ion-supplying fertilizer coated on the cloth material, wherein the water permeability coefficient of the cloth material is 6.00×10 ―3 cm / sec or more and 4.60×10 ―2 cm / sec or less. A fertilizing material, characterized in that: [2] The fertilizing material according to [1], wherein the iron ion-supplying fertilizer comprises steel slag and a humic acid-containing substance. [3] A method for supplying iron ions to a water area, comprising installing the fertilizing material according to [1] or [2] in any one water area selected from the group consisting of a sea area, a freshwater area and a brackish water area. [4] The method for supplying iron ions to a water area according to [3], wherein the fertilizing material is submerged and placed at the bottom of the water area. [5] The method for supplying iron ions to a water area according to [3], wherein the fertilizing material is laid at the bottom of the water area. [6] The method for supplying iron ions to a water area according to [3], wherein the fertilizing material is detachably attached to an artificial structure or a natural structure installed in the water area. [7] The method for supplying iron ions to a water area according to [3], wherein the fertilizing material is detachably attached near the water surface of the water area. [8] The water area is a sea area or a brackish water area, the fertilizing material is installed in the water area such that the vertical height relationship among the water level at high tide A, the water level at low tide A', the position of the upper end of the fertilizing material B, and the position of the lower end of the fertilizing material B' satisfies the following formula (1) and formula (2). The method for supplying iron ions to a water area according to [3], wherein: A>B' ...(1) B>A' …(2) [9] The water area is a sea area or a brackish water area, the method for supplying iron ions to a water area according to [3], wherein the fertilization material is installed in the water area such that the relationship among the vertical height of water level A at high tide, water level A' at low tide, upper end position B of the fertilization material and lower end position B' of the fertilization material satisfies the following formula (3) and formula (4). A≧B …(3) B'≧A' …(4)

[10] A method for constructing an algal bed, comprising constructing an algal bed using the fertilization material according to [1] or [2].

Effects of the Invention

[0016] According to the fertilization material of the present invention, both elution and diffusion of iron humate can be achieved regardless of the dissolved oxygen environment around the location where the fertilization material is installed, so that iron humate can be efficiently supplied to algae.

Brief Description of Drawings

[0017] [Figure 1] It is a cross-sectional view schematically showing an example of the fertilization material of the present invention. [Figure 2] It is a schematic diagram showing a construction example of the fertilization material according to an embodiment of the present invention. [Figure 3] It is a schematic diagram showing a construction example of the fertilization material according to an embodiment of the present invention. [Figure 4] It is a schematic diagram showing a construction example of the fertilization material according to an embodiment of the present invention. [Figure 5] It is a schematic diagram showing a construction example of the fertilization material according to an embodiment of the present invention. [Figure 6] It is a schematic diagram showing a construction example of the fertilization material according to an embodiment of the present invention. [Figure 7] It is a diagram showing the construction example illustrated in FIG. 6, wherein (a) and (b) are schematic diagrams showing the relationship between the water level height at high tide and the height of the upper end of the fertilization material. [Figure 8]Figure 6 shows an example of construction, where (a) and (b) are schematic diagrams showing the relationship between the height of the tide level at low tide and the height of the top of the fertilizer material. [Figure 9] Figure 6 shows an example of construction, where (a) and (b) are schematic diagrams showing the relationship between the height of the tide level at high tide and the height of the top of the fertilizer material. [Figure 10] Figure 6 shows an example of construction, where (a) and (b) are schematic diagrams showing the relationship between the height of the tide level at low tide and the height of the top of the fertilizer material. [Figure 11] This is a schematic diagram showing an example of the application of a fertilizer material according to an embodiment of the present invention. [Figure 12] This is a schematic diagram showing the dissolution test apparatus constructed in Test Example 1. [Figure 13] This graph shows the rate at which the dissolved oxygen concentration inside a fertilizer decreases after it has been immersed in seawater for 8 hours. [Figure 14] This graph shows the amount of dissolved iron released from fertilizer material after it has been immersed in seawater for 8 hours. [Figure 15A] This is a schematic diagram showing the experimental apparatus constructed in Test Example 2. [Figure 15B] This is a schematic diagram showing the experimental apparatus constructed in Test Example 2. [Figure 16] Figure 15A shows the experimental results obtained using the experimental apparatus shown, where (a) is a graph showing the change in dissolved oxygen concentration inside the iron ion supply fertilizer, and (b) is a graph showing the change in iron concentration at measurement positions X1 and X2. [Figure 17] Figure 15B shows the experimental results obtained using the experimental apparatus shown, where (a) is a graph showing the change in dissolved oxygen concentration inside the iron ion supply fertilizer, and (b) is a graph showing the change in iron concentration at measurement positions X1 and X3. [Figure 18] This is a schematic diagram showing the installation of the iron ion supply fertilizer in Test Example 3. [Figure 19] This figure shows the experimental results of the iron ion supply fertilizer in Test Example 3. [Modes for carrying out the invention]

[0018] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. Figure 1 shows a schematic diagram of the fertilizer material 1 of this embodiment. The fertilizer material 1 comprises a cloth material 3 and an iron ion supplying fertilizer material 2 covered with the cloth material 3.

[0019] When the fertilizer material 1 of this embodiment is placed in the water of a body of water, water permeates through the fabric to the iron ion supplying fertilizer material 2, and organic iron such as iron humate is leached from the iron ion supplying fertilizer material 2. The leached organic iron moves through the fabric 3 into the water outside. It is then supplied as nutrients to marine organisms such as algae and microorganisms growing in the body of water.

[0020] As shown in Figure 1, the iron ion supplying fertilizer 2 may be covered with the fabric material 3 in a single mass, or it may be divided into two or more masses and covered with one piece of fabric material 3. It is preferable that the entire iron ion supplying fertilizer 2 is covered with fabric material 3.

[0021] More specifically, the fertilizer material 1 can be exemplified as a material in which an iron ion supplying fertilizer material 2 is covered with a cloth material 3 having a certain shape.

[0022] For example, as a specific example of covering the iron ion supplying fertilizer 2 with the fabric material 3, it is preferable to process the fabric material 3 into a bag to form a fabric bag and contain the iron ion supplying fertilizer 2 inside the fabric bag. In this case, it is preferable to close the opening of the fabric bag. This allows the iron ion supplying fertilizer 2 to be covered with the fabric material 3.

[0023] Alternatively, the iron ion supplying fertilizer 2 may be pre-formed into a specific shape, and the entire surface of the formed iron ion supplying fertilizer 2 may be covered with a bag material (cloth material 3). This allows the iron ion supplying fertilizer 2 to be covered with the cloth material 3.

[0024] The shape of the fertilizer material 1 is not particularly limited and may be, for example, sheet-like, roughly spherical, roughly rectangular, etc.

[0025] The water permeability coefficient of the cloth material 3 is 6.00×10 ―3 cm / sec or more and 4.60×10 ―2 cm / sec or less. Accordingly, the dissolved oxygen concentration in the elution environment of the iron ion-supplying fertilizer material 2 can be maintained at less than 2.0 mg / L.

[0026] Examples of the material of the water-permeable cloth material 3 include polymer materials such as polyvinyl chloride, polyethylene, polyurethane and polylactic acid, natural organic materials including plant fibers such as hemp and coconut palm, and materials obtained by combining these materials. These materials are preferable because they do not contaminate water quality when brought into contact with water, and have sufficient strength to prevent tearing when the iron ion-supplying fertilizer material 2 is stuffed or placed in water. Further, the material of the cloth material 3 is not particularly limited as long as it can fulfill these functions.

[0027] In order to obtain an elution effect of divalent iron sufficient for seaweed to maintain a community in a water area by the fertilizer material 1 of the present embodiment, it is said that the iron concentration in the water area needs to be 100 nM or more, that is, 5.58 μg / L or more. When the dissolved oxygen concentration of water contained inside the mass of the iron ion-supplying fertilizer material 2 is less than 2.0 mg / L, the dissolved iron concentration in the water around the fertilizer material 1 is maintained at 10 μg / L or more, making it possible to supply an amount of iron sufficient for the growth of seaweed. In order to maintain the dissolved oxygen concentration of water contained inside the mass of the iron ion-supplying fertilizer material 2 at less than 2.0 mg / L, as described above, the water permeability coefficient of the cloth material 3 is set to 6.00×10 ―3 cm / sec or more and 4.60×10 ―2 cm / sec or less. The water permeability coefficient may be 4.00×10 ―2 cm / sec or less.

[0028] When the water permeability coefficient of the cloth material 3 is 4.60×10 ―2When the permeability exceeds cm / sec, the amount of water penetrating from the outside of fertilizer material 1 into the iron ion supplying fertilizer material 2 increases, which increases the supply of dissolved oxygen, making the environment for the dissolution of organic iron aerobic, causing divalent iron to be rapidly oxidized and reducing the amount of organic iron produced. On the other hand, when the permeability coefficient is 6.00 × 10⁻⁶ ―3 If the water flow rate is less than cm / sec, the outflow of water from the inside to the outside of the iron ion supply fertilizer 2 is insufficient, hindering the dissolution of organic iron generated inside, and reducing the amount of ferrous iron dissolved into the outside water. The permeability coefficient of the fabric material 3 is 6.00 × 10⁻⁶. ―3 cm / sec or more 4.60×10 ―2 By setting the rate to cm / sec or less, it becomes possible to achieve both the elution and diffusion of organic iron from the iron ion supply fertilizer 2.

[0029] The thickness of the fabric material 3 is not particularly limited, as long as it has enough strength to prevent the fabric material 3 from tearing when, for example, a fabric bag is made from the fabric material 3, the iron ion supplying fertilizer material 2 is placed in the fabric bag, and the bag is transported and installed.

[0030] The iron ion supplying fertilizer 2 can be any material installed in a body of water and used as a source of fertilizer for algae such as kelp and wakame, and is not particularly limited, but examples include fertilizers containing pure iron or alloys such as scrap iron, and fertilizers containing iron oxide such as scale sludge, cutting iron powder, red rust, and steel slag.

[0031] In particular, a slag-based fertilizer, which is a mixture of steel slag and a humic acid-containing substance, is preferably used as the iron ion supplying fertilizer 2. Slag-based fertilizers are suitable for supplying iron to water bodies because they can improve the efficiency of the dissolution performance of organic iron produced when humic acid, which acts as a chelating agent, coordinates with iron ions.

[0032] Steel slag serves as a source of iron, and it is preferable to use steelmaking slag with a relatively high iron content (total iron content of approximately 20% by mass or more). The steelmaking slag can include converter-type steelmaking slag and electric furnace-type steelmaking slag, as well as molten iron pretreatment slag and secondary refining slag produced from high-grade steel manufacturing processes that include pre- and post-converter processes (molten iron pretreatment, secondary refining), and even carbonated steelmaking slag that has undergone prior carbonation treatment.

[0033] Humic acid-containing substances are a general term for organic substances containing humic acid and fulvic acid, and a typical example is soil humic matter. This soil humic matter is a heterogeneous aggregate of large organic molecules ranging from yellow to black, which is formed when plant litter such as fallen leaves, fallen trees, and thinned wood are decomposed by soil microorganisms.

[0034] Other humic acid-containing substances besides soil humic matter include, for example, artificial humus. Artificial humus can be obtained by fermenting organic matter such as thinned wood and food waste, or fishery processing residues. Artificial humus can also be obtained by chemically treating lignite, as in commercially available fertilizers (fertilizer name: Azumin, manufactured by Denka Azumin Co., Ltd.). Artificial humus is rich in inorganic nitrogen and phosphorus, which can be easily absorbed as nutrients, so when fertilizer material 1 is used, these nutrients dissolve and become a source of nitrogen and phosphorus. Note that only one of these humic acid-containing substances may be used, or two or more may be used in combination. Since the humic acid in this humic acid-containing substance acts as an iron chelator, when used mixed with steel slag, the iron dissolved from the slag forms a complex with the humic acid and remains dissolved in the water for a long time, allowing algae to absorb the iron.

[0035] Next, the method for supplying iron ions to a body of water according to this embodiment will be described. The method for supplying iron ions to a body of water in this embodiment involves installing the above-mentioned fertilizer material 1 in one of the following bodies of water: a sea area, a freshwater area, or a brackish water area.

[0036] The following are examples of specific embodiments. Submerge fertilizer material 1 at the bottom of the water body (Figure 2). Place fertilizer material 1 on the bottom of the water body (Figure 3). The fertilizer material 1 is attached to an artificial or natural structure installed in a body of water in a manner that allows it to be easily attached and detached (Figure 4). The fertilizer material 1 is attached to the water surface of the body in a way that allows it to be easily attached and detached (Figure 5). Note that in Figures 3 to 5, the illustrations of the iron ion supplying fertilizer material 2 and the fabric material 3 have been omitted.

[0037] As shown in Figure 2, when sunk fertilizer material 1 to the bottom of a body of water such as a sea, freshwater, or brackish water (estuary), one or more units of fertilizer material 1 should be sunk to the bottom of the body of water. Here, the bottom of the body of water can be exemplified by the seabed, riverbed, lakebed, or swampbed.

[0038] As shown in Figure 3, when laying fertilizer material 1 on the bottom of bodies of water such as sea areas, freshwater areas, and brackish water areas (estuaries), the fertilizer material 1 is formed into a sheet and laid by spreading it out on the bottom of the body of water. When forming the sheet-shaped fertilizer material 1, the cloth material 3 may be formed into a cloth bag, the iron ion supplying fertilizer material 2 may be placed in the cloth bag, and then the sheet may be formed into an outer shape. Alternatively, the sheet-shaped iron ion supplying fertilizer material 2 may be covered with the cloth material 3. By forming the fertilizer material 1 into a sheet, the fertilizer material 1 can be transported in a rolled-up state, reducing the transport space and thus shortening the construction period.

[0039] As shown in Figure 4, when attaching fertilizer material 1 to an artificial or natural structure (hereinafter sometimes referred to as structure 9) installed in a body of water in a detachable manner, the fertilizer material 1 is attached to structure 9 using an attachment jig 10. Methods of attachment using the attachment jig 10 include, for example, tying it with a string or attaching it with a removable hook.

[0040] Furthermore, "detachable from the surface of structure 9" means that the fertilizer material 1, whose fertilizing effect has decreased, can be removed, the iron ion supplying fertilizer material 2 can be extracted from the fertilizer material 1, a new iron ion supplying fertilizer material 2 containing a sufficient amount of fertilizer components can be applied to the fabric material 3, and then the structure 9 to which it was originally attached can be reattached.

[0041] Artificial structures are not particularly limited as long as they are structures that can be attached to the surface or bottom of coastal waters such as freshwater, brackish water, or seawater, but examples include artificially molded and solidified structures, structures such as offshore wind power generation equipment, and civil engineering materials such as soil and sand packed into sandbags.

[0042] Natural structures are not limited to any structure on the surface or bottom of coastal waters (freshwater, brackish water, or saltwater) that can be used to attach fertilizer materials 1, but examples include rocks and bedrock.

[0043] As shown in Figure 5, when installing fertilizer material 1 in a body of water such as the sea, freshwater, or brackish water (estuary) in a way that allows it to be attached to and detached from the water surface, the fertilizer material 1 is suspended from structures such as aquaculture facilities or floating rafts using mounting fixtures 10. Examples of mounting fixtures 10 include ropes and hooks.

[0044] Furthermore, in the method for supplying iron ions to a body of water according to this embodiment, when installing the fertilizer material 1 in a sea area or brackish water area, the installation height of the fertilizer material 1 may be adjusted taking into account the ebb and flow of the tides.

[0045] The following are examples of specific embodiments. Place fertilizer material 1 along the shore of the water body (Figures 6-10). Place fertilizer material 1 near the water surface (Figure 11).

[0046] As shown in Figure 6, fertilizer material 1 is installed along the coast of a sea area or brackish water area (estuary), more specifically near the boundary between land L and water W. At the location where fertilizer material 1 is installed, the water level of water W fluctuates relative to the height of land L due to the ebb and flow of the tide. In Figure 6, dotted line A represents the water level at high tide, and dotted line A' represents the water level at low tide.

[0047] When burying the fertilizer material 1, it is preferable to select a location where seawater or brackish water permeates in order to supply iron to the water body W. Furthermore, the fertilizer material 1 may be covered with soil as shown in Figure 6, or, although not shown, the top surface of the fertilizer material 1 may be exposed without being covered with soil. Specifically, for example, the fertilizer material 1 may be installed at the waterline of a sandy beach. Alternatively, the fertilizer material 1 may be buried near the waterline of a sandy beach. Furthermore, a hole may be dug at the waterline of a sandy beach, and after retaining the soil, the fertilizer material 1 may be installed inside the hole. Moreover, the fertilizer material 1 may be installed in a suitable location on a rocky area. When installing the fertilizer material 1, it is preferable to install one or more units of the fertilizer material 1.

[0048] In this embodiment, the fertilizer material 1 should be installed such that the relationship between the water level A at high tide and the water level A' at low tide in the water body W, the position B of the upper end 1a of the fertilizer material 1, and the position B' of the lower end 1b of the fertilizer material 1 satisfies the following equations (1) and (2).

[0049] A > B' …(1) B > A' …(2)

[0050] The shape of the fertilizer material 1 shown in Figure 6 is rectangular, but the shape is not limited to this. The upper end 1a of the fertilizer material 1 may be the top surface when the fertilizer material 1 is installed. Position B of the upper end 1a is the vertical height of the upper end 1a when the fertilizer material 1 is installed, and may be the height of the top surface of the fertilizer material 1. If the top surface is a flat surface, the height of that flat surface is sufficient; if the top surface is a convex surface that rises upwards, the average height of that convex surface is sufficient.

[0051] The lower end 1b of the fertilizer material 1 may be the bottom surface when the fertilizer material 1 is installed. The position B' of the lower end 1b is the vertical height of the lower end 1b when the fertilizer material 1 is installed, and may be the height of the bottom surface of the fertilizer material 1. If the bottom surface is a flat surface, the height of that flat surface is sufficient, and if the top surface is a convex surface that rises downwards, the average height of that surface is sufficient.

[0052] Figure 7 shows the relationship between the water level A at high tide in the body of water W and the fertilizer material 1. The relationship between the height B' of the lower end 1b of the fertilizer material 1 when it is installed and the water level A at high tide satisfies A > B', as shown in equation (1). That is, as shown in Figure 7(a), the entire fertilizer material 1 may be lower than the water level A at high tide, and as shown in Figure 7(b), a part of the fertilizer material 1 may be lower than the water level A at high tide. On the other hand, the entire fertilizer material 1 must not be higher than the water level A at high tide.

[0053] Next, Figure 8 shows the relationship between the water level A' at low tide in the body of water W and the fertilizer material 1. The relationship between the height B of the upper end 1a of the fertilizer material 1 when it is installed and the water level A' at low tide satisfies B > A', as shown in equation (2). That is, as shown in Figure 8(a), a part of the fertilizer material 1 may be at a higher position than the water level A' at low tide, and as shown in Figure 8(b), the entire fertilizer material 1 may be at a higher position. On the other hand, the entire fertilizer material 1 must not be at a lower position than the water level A' at low tide.

[0054] Furthermore, in this embodiment, it is more preferable to install the fertilizer material 1 such that the relationship between water level A, water level A', and the vertical heights of positions B and B' of the fertilizer material 1 satisfies the following equations (3) and (4).

[0055] A ≥ B …(3) B'≧A' …(4)

[0056] Figure 9 shows the relationship between the water level A at high tide in the body of water W and the fertilizer material 1. When installing the fertilizer material 1, the relationship between the height B of the upper end 1a of the fertilizer material 1 and the water level A at high tide preferably satisfies A > B, as shown in equation (3). That is, as shown in Figure 9(a), the entire fertilizer material 1 may be at a lower position than the water level A at high tide, and as shown in Figure 9(b), the position B of the upper end 1a of the fertilizer material 1 and the water level A may be at the same position, while the entire fertilizer material 1 must not be at a higher position than the water level A at high tide.

[0057] Next, Figure 10 shows the relationship between the water level A' at low tide in the body of water W and the fertilizer material 1. When installing the fertilizer material 1, the relationship between the height B' of the lower end 1b of the fertilizer material 1 and the water level A' at low tide preferably satisfies B'>A', as shown in equation (4). That is, as shown in Figure 10(a), a part of the fertilizer material 1 may be at a higher position than the water level A' at low tide, and as shown in Figure 10(b), the position B' of the lower end 1b of the fertilizer material 1 and the water level A' may be at the same level. In Figure 10(b), the lower end 1b of the fertilizer material 1 is in contact with the water level at low tide. On the other hand, the entire fertilizer material 1 must not be at a lower position than the water level A' at low tide.

[0058] The fertilizer material 1 shown in Figures 6 to 10 is buried in land L, but since it is in a place where seawater or brackish water permeates, the installation height of the fertilizer material 1 satisfies equations (1) and (2), or equations (3) and (4), so that, as shown in Figures 7 to 10, part or all of it is submerged at high tide, and at low tide, the part that was submerged at high tide is above the water surface. When part or all of the fertilizer material 1 is submerged at high tide, water permeates into the interior of the fertilizer material 1, and iron diffusion into the water occurs inside the fertilizer material 1. Subsequently, at low tide, the part that was submerged at high tide is above the water surface, so water flows out from inside the fertilizer material 1 to the outside, and iron also flows out at the same time. In this way, the tidal difference in water level in the seawater or brackish water area promotes the outflow of iron from the fertilizer material 1, and more iron is diffused into the seawater or brackish water area.

[0059] Next, in the iron ion supply method of this embodiment, the fertilizer material 1 may not be buried, but rather placed near the water surface.

[0060] For example, as shown in Figure 11, a frame 10 may be installed at the bottom F of the water body W, and the fertilizer material 1 may be placed on the frame 10. In this case, as described above, it is preferable to install the material so that the relationship between the water level A at high tide, the water level A' at low tide, and the vertical heights of the upper end 1a B and lower end 1b B' of the fertilizer material 1 satisfies equations (1) and (2), or more preferably equations (3) and (4).

[0061] By installing the fertilizer material 1 on the frame 10 in a manner that satisfies equations (1) and (2), preferably equations (3) and (4), the outflow of iron from the fertilizer material 1 is promoted by the tidal difference in water level in the seawater or brackish water area, as shown in Figures 7 to 10, and more iron is dispersed into the seawater or brackish water area.

[0062] Next, the seaweed bed creation method of this embodiment involves creating a seaweed bed using the above-mentioned fertilizer materials.

[0063] For example, fertilizer material 1, as shown in Figure 1, can be placed in areas where seaweed beds need to be restored or created, such as areas affected by coastal barrenness. Examples of such areas include beach nourishment areas, tidal flats, shallow areas, seaweed beds, and fishing grounds. This also includes areas where fertilizer material 1 is placed with the intention of creating tidal flats or seaweed beds, but which have not yet become tidal flats or seaweed beds.

[0064] The fertilizer material 1 of this embodiment can be installed at any location in the water. In situations where sunlight necessary for photosynthesis reaches the bottom, or where organic iron dissolved from the fertilizer material 1 is carried to a depth where photosynthesis is possible by upwelling currents, it can be sunk or laid at the bottom of the water body. Furthermore, in the case of deep water, it can be installed at any depth in the water by attaching it to an artificial or natural structure installed in the water body in a detachable manner, or by attaching it to a detachable manner near the water surface of the water body. The fertilizer material 1 of this embodiment can be prepared in large quantities in advance or manufactured during the installation process. Specific examples of the installation of the fertilizer material 1 are shown in Figures 2 to 5 or Figure 11. In addition, as shown in Figure 6, the fertilizer material 1 may be buried on land adjacent to a seawater or brackish water area in a place where seawater or brackish water can permeate. [Examples]

[0065] The fertilizer material of the present invention will be described in detail below.

[0066] [Test Example 1] The relationship between the dissolved oxygen concentration inside an iron ion-supplying fertilizer covered with a mesh-like fabric material having different permeability coefficients and the dissolved iron leached to the outside of the fabric material was investigated.

[0067] As the steel slag, we used converter-type steelmaking slag that had undergone carbonation treatment and had the composition shown in Table 1 below. In addition, as the humic acid-containing material, we used artificial humus soil made by fermenting a mixture of thinned wood, fish and shellfish processing residues, and cow manure. These steel slag and humic acid-containing material were mixed in a mass ratio of 2:1 to prepare iron ion-supplying fertilizer 2.

[0068] [Table 1]

[0069] Five types of polyester mesh bags manufactured by tantore Co., Ltd. were prepared, along with a hemp bag. The polyester mesh bags were numbered #317 / 660-1 (hereinafter referred to as No. 1), #317 / 660-1 (hereinafter referred to as No. 2), #109-150 (hereinafter referred to as No. 3), #51-300 (hereinafter referred to as No. 4), and #30-700 (hereinafter referred to as No. 5). The hemp bag was designated No. 6.

[0070] For these five types of polyester mesh bags (No. 1-5) and hemp bag (No. 6), the permeability coefficient of the fabric material 3 used in each bag was measured in accordance with JIS A 1218:2020. Specifically, a cylindrical container with an inner diameter of 100 mm, a length of 120 mm, and open at the top and bottom was prepared. A 20 cm x 20 cm test piece (fabric material) was also prepared. The test piece was attached to the bottom opening of the cylindrical container, water was poured from the top of the cylindrical container, and the amount of water that passed through the test piece and flowed down was measured. Three test pieces were prepared for each sample, and each was measured, and the average value of the three measurements was calculated. The permeability coefficient [cm / sec] is (permeability [cm 3 ] × test specimen thickness [cm]) / (water flow time [sec] × water head difference [cm] × water flow area [cm] 2 The calculation was performed using the method described below. The actual tests were conducted at the Japan Textile Products Quality Technology Center (https: / / www.qtec.or.jp / ). The test procedure was carried out according to the guidelines described on the Japan Textile Products Quality Technology Center website (https: / / www.qtec.or.jp / search / test / sangyo-kinou / sangyo-kinou02 / ). The average value of three measurements of the permeability coefficient is shown in Table 2.

[0071] [Table 2]

[0072] As shown in Figure 12, 180g of the prepared iron ion supplying fertilizer 2 was placed in bags (cloth material 3) No. 1 to 6 to form fertilizer material 1. Each fertilizer material 1 was placed in a 3L acrylic container 11, and a dissolved oxygen concentration measuring sensor 5 for measuring the dissolved oxygen concentration inside the iron ion supplying fertilizer 2 was installed inside the bag (cloth material 3) of fertilizer material 1. In this way, the elution test apparatus shown in Figure 12 was constructed. The elution test apparatus was constructed for each cloth material (No. 1 to 6). In Figure 12, reference numeral 4 denotes seawater, reference numeral 6 denotes a vinyl tube for circulating seawater, reference numeral 7 denotes a pump for sending seawater, and reference numeral 8 denotes a tank filled with seawater. Note that the iron ion supplying fertilizer 2 and cloth material 3 are not shown in Figure 12.

[0073] Filtered seawater collected from Tokyo Bay was continuously passed through elution test devices No. 1 to No. 6 at a flow rate of 20 ml / min for 8 hours. Dissolved oxygen concentrations were measured at 0 hours and 8 hours after the start of water flow. In addition, the dissolved iron concentration in the seawater was measured using a trace iron analyzer at 0, 1, 2, 4, 6, and 8 hours after the start of water flow. When measuring the dissolved iron concentration in the seawater, the tip of a syringe with a tube was placed near fertilizer material 1 in the elution test device shown in Figure 12, and seawater near fertilizer material 1 was collected using the syringe. The collected seawater was then measured using a trace iron analyzer.

[0074] The dissolved oxygen concentration inside the iron ion-supplying fertilizer 2 is determined by the balance between oxygen consumption during the decomposition of organic matter contained in the artificial humus soil and oxygen supply from the inflow of oxygen-rich seawater from the outside. Therefore, in this study, we calculated the rate of decrease in dissolved oxygen concentration over a period of 0 to 8 hours as an indicator of this balance.

[0075] Figure 13 shows the relationship between the hydraulic conductivity and the rate of decrease in dissolved oxygen concentration. Figure 14 shows the relationship between the hydraulic conductivity and the amount of dissolved iron leached within 8 hours. The amount of dissolved iron was determined from the dissolved iron concentration in seawater.

[0076] As shown in Figure 13, the smaller the permeability coefficient, the greater the rate of decrease in dissolved oxygen concentration, and the more easily the internal environment of the iron ion supplying fertilizer 2 covered with the fabric material 3 becomes anaerobic.

[0077] On the other hand, as shown in Figure 14, the amount of dissolved iron was 182 μg for No. 1 (Comparative Example), 330 μg for No. 2 (Example), and 320 μg for No. 3 (Example), showing nearly twice the amount of dissolved iron compared to No. 1. Furthermore, the amount of dissolved iron decreased to about 200 μg for No. 4, 5, and 6 (Comparative Examples).

[0078] From these results, the permeability coefficient of fabric material 3 is 6.47 × 10 -3 cm / sec or more 4.53×10 -2 It was found that it is possible to efficiently supply iron in a range of cm / sec or less.

[0079] [Test Example 2] In a method of burying iron ion-supplying fertilizer, we investigated the relationship between iron leaching due to diffusion expected at high tide and iron leaching due to the movement of seawater from within the iron ion-supplying fertilizer during low tide.

[0080] Iron ion supplying fertilizer 2 was prepared in the same manner as in Test Example 1 described above.

[0081] As shown in Figures 15A and 15B, an acrylic column container with an inner diameter of 100 mm and a length of 475 mm was filled with layers of sand S, the prepared iron ion-supplying fertilizer 2, and sand S, each layered to a depth of 100 mm. A dissolved oxygen sensor D was inserted at the location of the iron ion-supplying fertilizer 2, and the dissolved oxygen concentration inside the iron ion-supplying fertilizer 2 was measured. Two such experimental setups were prepared.

[0082] In the experimental setup shown in Figure 15A, to simulate the tidal cycle of high and low tides, the setup was repeatedly immersed in seawater up to the dotted line Y1 for 6 hours, followed by a drying period where the seawater was removed up to the dotted line Y2 for 6 hours. Measurement position X1 in Figure 15A is directly below the seawater surface (dotted line Y1) during the immersion period. Measurement position X2 is at the very bottom of the column.

[0083] In the experimental setup shown in Figure 15B, to simulate the tidal cycle of high and low tides, a 6-hour immersion period was repeated, during which seawater was added up to the position of the dotted line Y1, and a 6-hour drying period was repeated, during which seawater was removed up to the position of the dotted line Y3. Measurement position X1 in Figure 15B is directly below the seawater surface (dotted line Y1) during the immersion period. Measurement position X3 is directly above the iron ion supplying fertilizer 2.

[0084] In the experimental setup shown in Figure 15A, it was simulated that the entire iron ion-supplying fertilizer 2 would be below the water surface at high tide, and above the water surface at low tide. In the experimental setup shown in Figure 15B, it was simulated that the entire iron ion-supplying fertilizer 2 would be below the water surface in both high and low tide conditions.

[0085] Furthermore, since the dissolved oxygen concentration of seawater in coastal areas is generally saturated, filtered seawater collected from Tokyo Bay was used for injection. The filtered seawater was pre-aerated before use.

[0086] Then, to confirm the leaching of iron, the iron concentration of seawater at measurement position X1, set at the top of the column, was measured for each of the two experimental apparatuses 6 hours after the start of immersion.

[0087] Next, to confirm the elution of iron associated with tides (advection diffusion), seawater was drawn from measurement position X2 at the bottom of the column in the experimental apparatus shown in Figure 15A, and from measurement position X3 in the middle of the column in the experimental apparatus shown in Figure 15B, and the iron concentration was measured in each case.

[0088] The iron concentration was measured using an ICP emission spectrometer. This procedure was repeated 18 times.

[0089] Figures 16 and 17 show the dissolved oxygen concentration inside the iron ion supply fertilizer 2 in each experimental apparatus, and the change in iron concentration at measurement positions X1, X2, and X3 over time.

[0090] Figure 16 shows the experimental results using the experimental apparatus shown in Figure 15A. (a) shows the change in dissolved oxygen concentration inside the iron ion supply fertilizer 2 when the seawater surface is repeatedly varied between positions Y1 and Y2. (b) shows the change in iron concentration at measurement positions X1 and X2 when the seawater surface is repeatedly varied between positions Y1 and Y2. In Figure 16(b), the ▲ plot represents the iron concentration at measurement position X1, and the ● plot represents the iron concentration at measurement position X2.

[0091] Figure 17 shows the experimental results using the experimental apparatus shown in Figure 15B. (a) shows the change in dissolved oxygen concentration inside the iron ion supply fertilizer 2 when the seawater surface is repeatedly varied between positions Y1 and Y3. (b) shows the change in iron concentration at measurement positions X1 and X3 when the seawater surface is repeatedly varied between positions Y1 and Y3. In Figure 17(b), the ▲ plot represents the iron concentration at measurement position X1, and the ● plot represents the iron concentration at measurement position X3.

[0092] As shown in Figure 16(a), the dissolved oxygen concentration inside the iron ion-supplying fertilizer 2 in the experimental apparatus shown in Figure 15A increased when the iron ion-supplying fertilizer 2 was exposed to the air, and then rapidly decreased to a low-oxygen environment of 0 mg / L.

[0093] On the other hand, as shown in Figure 17(a), the dissolved oxygen concentration inside the iron ion supply fertilizer 2 in the experimental apparatus shown in Figure 15B remained at 0 mg / L throughout the test period.

[0094] Furthermore, the iron concentration at measurement position X1 at the top of the column after 6 hours was low, similar to that of the injected seawater, in both experimental setups shown in Figures 15A and 15B, suggesting low elution due to diffusion.

[0095] Furthermore, as shown in Figure 16(b), the iron concentration of seawater at measurement position X2 in the experimental apparatus shown in Figure 15A was in the range of 2 mg / L to 5.5 mg / L during the test period. On the other hand, as shown in Figure 17(b), the iron concentration of seawater at measurement position X3 in the experimental apparatus shown in Figure 15B was less than 1.8 mg / L, and the iron concentration of seawater collected from measurement position X2 in the experimental apparatus in Figure 15A was higher. From this, it is suggested that the iron elution rate from the iron ion supply fertilizer 2 is higher when the iron ion supply fertilizer 2 is installed in a location where it is exposed to the elements than when it is installed in a location where it is not exposed to the elements.

[0096] [Test Example 3] In the test plot in Shimanto City, Kochi Prefecture, burlap sacks filled with iron ion-supplying fertilizer were prepared. The iron ion-supplying fertilizer was the same as that used in Test Examples 1 and 2. The burlap sacks were the same as those used in Test Example 1 (No. 6). A dissolved oxygen concentration meter was inserted into the iron ion-supplying fertilizer.

[0097] Then, burlap sacks filled with iron ion-supplying fertilizer were placed at a depth of approximately 50 cm below the ground surface and covered with soil. Since the tide level at the time of placement was approximately the same as the ground surface level, the positional relationship of the iron ion-supplying fertilizer was shown in Figure 18, based on that tide level.

[0098] Figure 18 shows the average water level during spring tides. 0 cm represents the average water level at low tide during spring tides. The tidal levels were referenced from the tide table for Shimoda, Kochi Prefecture (data published by the Japan Meteorological Agency), which is closest to the test area. In Figure 18, 84.3 cm represents the ground surface height relative to 0 cm, 44.3 cm represents the top surface height of the iron ion supplying fertilizer relative to 0 cm, and 34.3 cm represents the bottom surface height of the iron ion supplying fertilizer relative to 0 cm.

[0099] The experiment was conducted over a six-month period. Figure 19 shows the data for the three days from 0:00 AM on January 12, 2024 to 0:00 AM on January 15, 2024, along with the relationship between the tidal changes in water level and the location of the iron ion-supplying fertilizer during that period.

[0100] As shown in Figure 19, the dissolved oxygen concentration in the iron ion-supplying fertilizer rises sharply when the fertilizer is exposed at low tide, and then decreases as it is subsequently submerged. From this, it was hypothesized that by installing the iron ion-supplying fertilizer so that its bottom surface is above high tide and its top surface is above low tide, creating a condition in which the dissolved oxygen concentration inside the fertilizer repeatedly rises and falls, the iron dissolved into the interstitial water inside the fertilizer can be effectively diffused into the sea, thereby increasing the fertilization effect. [Explanation of symbols]

[0101] 1…Fertilizer materials 2…Iron ion supplying fertilizer 3…Cloth material 4…Seawater 5… Dissolved oxygen concentration measuring sensor 6… Vinyl tube 7... Pump 8...Seawater tanks 9...Structure 10…Mounting jig 11…Acrylic container

Claims

1. Fabric material, The system comprises an iron ion supply fertilizer covered with the aforementioned fabric material, The permeability coefficient of the aforementioned fabric is 6.00 × 10 ―３ cm / sec or more, 4.60×10 ―２ A fertilizer material characterized by having a concentration of cm / sec or less.

2. The fertilizer material according to claim 1, characterized in that the iron ion supplying fertilizer material contains steel slag and a humic acid-containing substance.

3. A method for supplying iron ions to a body of water, characterized by installing the fertilizer material described in claim 1 or claim 2 in one of the following bodies of water: a sea area, a freshwater area, or a brackish water area.

4. The method for supplying iron ions to a body of water according to claim 3, characterized in that the fertilizer material is submerged at the bottom of the body of water.

5. The method for supplying iron ions to a body of water according to claim 3, characterized in that the fertilizer material is laid at the bottom of the body of water.

6. The method for supplying iron ions to a body of water according to claim 3, characterized in that the fertilizer material is attached to an artificial or natural structure installed in the body of water in a manner that allows it to be detachably attached.

7. The method for supplying iron ions to a body of water according to claim 3, characterized in that the fertilizer material is attached to the water surface of the body of water in a manner that allows it to be detachably attached.

8. The aforementioned body of water is either a sea area or a brackish water area. A method for supplying iron ions to a body of water according to claim 3, wherein the fertilizer material is installed in the body of water such that the relationship between the water level A at high tide, the water level A' at low tide, the position B of the upper end of the fertilizer material, and the position B' of the lower end of the fertilizer material satisfies the following equations (1) and (2). A > B' ... (1) B > A' ... (2)

9. The aforementioned body of water is either a sea area or a brackish water area. A method for supplying iron ions to a body of water according to claim 3, wherein the fertilizer material is installed in the body of water such that the relationship between the water level A at high tide, the water level A' at low tide, and the vertical heights of the upper end B and lower end B' of the fertilizer material satisfies the following equations (3) and (4). A ≥ B …(3) B'≧A' …(4)

10. A method for creating a seaweed bed, characterized by creating a seaweed bed using the fertilizer material described in claim 1 or claim 2.

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