JPH08243538A - Method and device for suppressing propagation of phytoplankton - Google Patents

Abstract

PURPOSE: To obtain a method and device for suppressing the propagation of phytoplankton which allow the inexpensive and easy installation of the device in a water basin, such as shallow lake or pond, by disposing light shielding members to cover water of the volume of a specific ratio in terms of the total volume of the water of the water basis on the front surface the water basin or within the water basin. CONSTITUTION: The light shielding members which cover the water of the volume of 1/3 to 2/3 in terms of the total volume of the water in the water basin are disposed on the front surface of the water basin or within the water basin in order to suppress the propagation of the phytoplankton generated in the stagnating water basin of the lake, pond, etc. For example, natural plants are disposed as the light shielding members in the water basin of the lake or pond. Namely, emergent plants 10, such as reeds, and floating leaves 11, such as water caltrops, are cultured and disposed to the prescribed area. The light shielding plants are preferably artificial structures, i.e., reed rafts or water culture plant rafts or are further preferably light shielding sheets. As a result, the method and device for suppressing the propagation of the phytoplankton which allow the effective and easy disposition of the device even in the water basin of the relatively shallow lake or pond at the relatively low cost are obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phytoplankton growth suppressing method and apparatus for suppressing the growth of phytoplankton generated in a water area where lakes and marshes are stagnant.

[0002]

2. Description of the Related Art In eutrophication lakes and the like, not only phytoplankton is abnormally generated and the appearance is impaired, but fish are also affected by obstruction of gill respiration and death due to lack of oxygen in the bottom water. However, it causes water quality problems such as musty odor to the water supply. Conventionally, as measures for preventing the growth of such phytoplankton, (1) a method of suppressing the growth of phytoplankton by removing nutrient salts such as phosphorus and nitrogen in water flowing into lakes and marshes, (2) Copper sulfate (C
uSO ₄ ), chlorine (Cl ₂ ) and other so-called algaecides are used to kill phytoplankton, (3) Oil water is artificially circulated using an air pump, etc. The method of suppressing the growth of phytoplankton by introducing it into the inside has been performed.

[0003]

However, of the above-mentioned measures, the method of removing the nutrient salts flowing into a lake or the like is not easy to employ because the construction cost of the treatment facility and the running cost increase. Moreover, nutrient salts from unspecified pollutants cannot be removed, so they are not effective. Also,
Even when phytoplankton is killed by an algaecide, if the water of the lake is used for multiple purposes, it may contaminate the water, which is a problem that is difficult to adopt. Furthermore, the method of forcibly circulating the lake water to shorten the residence time of the surface water cannot be applied because the effect is not effective when the water depth is shallow (average water depth of 5 m or less). The present invention, in view of the problems of the conventional method for abnormal growth and suppression of phytoplankton as described above, at a relatively low price,
It is another object of the present invention to provide a phytoplankton growth suppression method and device that is effective and can be easily arranged in water such as shallow lakes and marshes. MEANS TO SOLVE THE PROBLEM In order to achieve the said objective, first, the growth factor of phytoplankton was examined, and the inflow of the above-mentioned nutrient sources, such as nitrogen and phosphorus, water temperature, surface residence time, carbon dioxide concentration, spore dispersion, various light, etc. Among the factors of
The present invention has been achieved as a result of diligent study on the blocking effect, particularly focusing on light.

[0004]

According to the present invention, on the surface of or inside a body of water, the total amount of water in the body of water is 1/3 to.
There is provided a method for suppressing the growth of phytoplankton, which comprises disposing a light shield that covers 2/3 of the amount of water.
In the phytoplankton growth inhibitory method of the present invention, the light blocker is an organism, water hyacinth, duckweed or duckweed, and a mixture thereof, is an artificial structure, Acrid or hydroponic plant squid. Or a light shielding sheet.
Further, the present invention comprises a light shielding sheet and a floating body detachably attached to each corner portion of the light shielding sheet and capable of floating on the surface of a water body, and a plurality of light shielding sheets are provided through the respective floating bodies. Provided is a phytoplankton growth inhibitor, which is characterized in that the sheets are connected in a plane. In this phytoplankton growth inhibitor, it is preferable that a reinforcing wire is arranged on each side connecting the corner portions of the light shielding sheet.

[0005]

The present invention is configured as described above, and converts light in a water body such as a lake into a predetermined amount, that is, the total amount of water in the water body to 1 /
A predetermined light blocker is provided on the surface or in the middle layer of a water body such as a lake to cover the water amount of 3 to 2/3 to block light. The light shielding area of the present invention will be described. It is well known that sunlight energy is essential for the growth of phytoplankton of algae such as water-bloom. Therefore, it is also known that light can be blocked in order to prevent or suppress the growth of phytoplankton. However, when the light is completely shielded, the water quality in water bodies such as lakes cannot be maintained well. That is, the quality of water changes depending on the dissolved oxygen concentration,
It is said that good quality water is always in a predetermined aerobic state. Therefore, dissolved oxygen for keeping water in the water area aerobic is often supplied by oxygen due to the assimilation of phytoplankton of algae. Therefore, when the phytoplankton in the water area becomes too small, there is a risk that oxygen deficiency will occur in the water. Based on the above findings, it was also reported that the growth potential of phytoplankton in the dark was reduced to 70% of the growth potential in the light after 3 days and decreased by 80% after 5 days (Ishikawa Toshihide " Botany magazine "Vol. 69, 7-16
Page, published by the Botanical Society of Japan in 1960), and empirical data by the inventor shows that phytoplankton can grow 50 to 150% by weight in 5 days in the light. As a result, the residence time in the light of water in the water is twice as long as that in the dark, and the growth of phytoplankton can be suppressed. On the other hand, the light area can be appropriately selected depending on the required dissolved oxygen concentration, but normally the dissolved oxygen concentration is 30% by weight or more, and phytoplankton has about 10 times as much oxygen as self-consumed oxygen assimilated. Since it occurs, it is preferable that the amount of water corresponding to about 1/2 of the dark place is not shielded from light, and the amount of water corresponding to 2/3 of the total amount of water in the water area can be shielded. in this case,
In many cases, the water depth is not constant in lakes and marshes.For example, even if a light blocker is installed over a wide shallow area, the effect of suppressing the growth of phytoplankton will be low. This is because it is necessary to use the converted light-shielding area. The place where the water surface is shaded and the place where the water is not shaded are normally exchanged by the force of the wind, but if the water flow is insufficient, it can be compensated by a pump or aeration. It is not necessary to move the shading area actively. As described below, a light shield such as a plant or a floating island is suitable because it floats and the light-shielding portion automatically changes.

As the light shield of the present invention, various kinds can be used. For example, originally, water hyacinths that are plants that proliferate on lake water, natural plants such as duckweed, duckweed, structures such as floating islands such as artificially produced squid and hydroponic plants such as floating islands, and synthetic resin, Various light blocking sheets such as rubber and cloth can be used. Further, the method of disposing the light blocker can be appropriately selected from various methods.For example, in the case of organisms such as the above plants, the light shielding area can be managed in a floating state on the water surface, or an artificial structure can be used. By using a predetermined means such as a weight or a chain, the water surface can be freely floated or floated at a predetermined position, or can be held in water. Further, the light shielding sheet can be arranged in a floating or fixed state on the water surface and in the water by a predetermined fixing means, like the artificial structure. Furthermore, in order to extend the residence time of the lake water in the shaded water area, a string-like, bar-like,
A pump or aeration device may be used to suspend the plate-like object to impede the water flow or, conversely, to reduce the residence time. Further, the pump and the aeration device may be used in combination with those installed for better maintaining the water quality depending on the surrounding environment of the water area where the light shield is arranged. Further, in the present invention, if necessary, other water quality improving methods may be used in combination.

According to the phytoplankton growth suppressing apparatus of the present invention, a plurality of light blocking sheets are connected in a planar manner via each floating body detachably attached to each corner of the light blocking sheet. Since it is made of a light shielding sheet, it is possible to adapt it to the shape of a lake by devising the connection shape of the light blocking sheet, which makes it possible to inhibit the photosynthesis of phytoplankton and suppress the growth of phytoplankton. . Further, the light blocking sheet is preferably made of a synthetic resin such as polyvinyl chloride and has a light reflecting film formed on at least one surface thereof, so that a large light blocking effect can be obtained. Further, since the light blocking sheet is formed in a quadrilateral shape, it is easy to handle each sheet, and since reinforcing wires are arranged on each side connecting the corners of the sheet, a natural wire is provided. The durability against the phenomenon can be secured.

[0008]

Embodiments of the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited to the following examples. FIG. 1 is a conceptual explanatory view of a case where the above-mentioned natural plant is arranged in a lake water as a light blocker. In FIG. 1, a drawn water plant 10 such as a reed or a floating leaf 11 such as a reed is cultivated and arranged in a lake water area 1 so as to have a predetermined area. FIG. 2 is a conceptual explanatory diagram in which a floating island, which is an artificial structure, is arranged as a light shield in a lake water area. In Fig. 2, floating islands 2 constructed of plastic etc.
At 0, a reed is planted in the upper part, and further, a suspended object 21 made of a metal chain is provided in the bottom part so as to be fixed at a substantially predetermined position, and is suspendedly arranged so as to cover a predetermined surface of the lake water area 1. . In addition, the pumping and aeration device 22 is arranged in the water area where the floating island 20 is not arranged so as to be able to cope with an abnormality. FIG. 3 is a conceptual explanatory view of another embodiment in which the artificial structure of FIG. 2 is arranged in a lake water area, in which the floating island 20 is fixed by a rope or the like on the shore without floating. is there. FIG. 4 is a conceptual explanatory view in which a light blocking sheet as a light blocking body is arranged in the water of the lake water area 1 at a depth of about 50 to 100 cm from the water surface. In FIG. 4, a light-shielding sheet 30 made of vinyl is fixed to the lake shore with a rope at a depth of 1 m in the lake water area 1, and is spread in water so as to correspond to a predetermined area of the water surface. . Also in this case, as in FIGS. 2 and 3, the pumped-up aeration apparatus 22 is arranged in water so as to be able to cope with an abnormality.

Next, as a more specific example of the phytoplankton growth suppressing method of the present invention, an embodiment of a phytoplankton growth suppressing device in which a light-shielding sheet is arranged so as to cover the surface of a body of water is shown. Will be described with reference to. In particular, this embodiment can be suitably applied to reservoirs installed in various factories. FIG. 5 is a perspective view showing the appearance of a single light shielding sheet. The light blocking sheet 50 is formed in a quadrilateral shape, preferably a square shape, and metal fittings 51 for engagement are attached to respective corner portions. FIG. 6 is an enlarged cross-sectional view of the light shielding sheet in which the broken line AA in FIG. 5 is viewed in the arrow direction. The light shielding sheet 50 is a synthetic resin sheet 50a such as vinyl, and this synthetic resin sheet. It is composed of one surface of 50a, preferably a light reflecting film 50b formed on the surface thereof. The light reflecting film 50b may be formed of, for example, aluminum in a thin film shape, or may be formed by mixing a light reflecting substance in a synthetic resin material.
A reinforcing wire 50c is arranged on each side connecting the corners of the light shielding sheet 50. This wire 50c
Is formed so that each side of the light shielding sheet 50 is polymerized into a bag shape by means of a high-frequency welder or the like, and is inserted into the polymerized hollow portion. The wire 50c is led out at each corner of the seat 50, and the engaging metal fittings 51 are attached to the lead-out portions. FIG. 7 shows the structure of a floating body that can float on the water surface. The floating body 52 has a hollow inside and air is enclosed in a hermetically sealed state. In the illustrated example, the appearance is substantially cubic. The engaging portions 12a are integrally formed on the four side surfaces of the floating body 52, and the fittings 51 attached to the corners of the seat 50 can be attached to and detached from the engaging portions 52a. It is adapted to be engaged. Therefore, by engaging the metal fittings 51 for engagement, which are attached to the corners of the light blocking sheets 50, with the engaging portions 52a of the floating bodies 52, the plurality of light blocking sheets 50 can be connected via the floating bodies 52. It can be connected in a plane.

FIG. 8 shows a state in which a plurality of light shielding sheets 50 are connected in a plane via the floating bodies 52. FIG.
The example shown in FIG. 4 shows a state in which four light shielding sheets 50 are vertically connected and four light shielding sheets are horizontally connected, that is, a total of 16 sheets are connected in a plane shape. By changing the mode, the overall shape can be made to match the shape of the lake. In this way, a plurality of light shielding sheets 50 are connected in a plane via the floating body 52, and one end of the rope 13 is tied to the engaging portion 52a of the specific floating body 52 as shown in FIG. By connecting the end to the shore,
It is possible to fix the entire assembled light blocking sheets 50 at a predetermined position in the lake. Therefore, the above-mentioned light shielding sheet 50 is combined through the floating body 52 so as to form a lake, and as described above, it is covered so as to be about 1/3 to 2/3 in terms of the total amount of water in the lake water area. It is possible to effectively suppress the growth of phytoplankton by creating a condition to shield light by using this method. In the above example,
Although the shape of the light blocking sheet 50 is formed in a square shape, the shape of the light blocking sheet is not limited to a specific shape as shown in the embodiments, and may be formed in, for example, a triangle or a hexagon. . Further, as the light blocking sheet 50, the one in which a light reflecting film is formed on the surface of vinyl resin is shown.
For example, a cloth-like sheet may be used, and when a relatively thick cloth-like sheet is used, the strength of the sheet can be ensured to some extent, so that a reinforcing sheet provided on each side of the sheet is used. The wire 50c can be eliminated. Further, the shape of the floating body 52 does not have to be a cubic shape as in the embodiment, and may be, for example, a ball shape.
The engaging portion 52a formed integrally with the above may not be independently provided on the four side surfaces but may be provided at one location.

[0011]

INDUSTRIAL APPLICABILITY The present invention can effectively suppress abnormal growth of phytoplankton by arranging a light blocker in a predetermined area in a stagnant water area such as a lake and marshes, and improve the water quality of the water area. It can be maintained easily and satisfactorily, which is preferable in a hygienic environment. Further, each light blocker can be variously selected according to a natural water area such as a lake or a marine water area, a water area in which a reservoir in a factory is installed, and the environment of the surrounding area in which it is installed is not damaged. In addition, each light blocker can be easily adapted to the shape of the water area in which it is arranged, whereby photosynthesis of phytoplankton can be blocked and growth of phytoplankton can be effectively suppressed. Further, when using a light blocking sheet, it is possible to provide a light blocking sheet may be provided with a light reflecting film on at least one surface thereof, it is possible to provide at a low cost, it is also possible to obtain a sufficient light blocking effect, Suitable for water in the factory grounds. Further, a reinforcing wire can be arranged on each side connecting the corners when the light shielding sheet is arranged, and durability against natural phenomena such as wind can be secured.

[Brief description of drawings]

FIG. 1 is a conceptual explanatory view of an embodiment of the present invention in which a natural plant is arranged as a light blocker.

FIG. 2 is a conceptual explanatory view of another embodiment of the present invention in which a floating island is provided as a light shield.

FIG. 3 is a conceptual explanatory view of another embodiment of the present invention in which a floating island is provided as a light shield.

FIG. 4 is a conceptual explanatory view of another embodiment of the present invention in which a sheet-like body is disposed in water as a light shield.

FIG. 5 is a perspective view showing the external appearance of a light blocking sheet used in an embodiment of the device of the present invention.

6 is an enlarged vertical cross-sectional view of the light-shielding sheet shown in FIG. 5, taken along the line AA in the arrow direction.

FIG. 7 is a perspective view showing an example of a floating body used in one embodiment of the apparatus of the present invention.

FIG. 8 is a plan view showing a usage state in which light blocking sheets are combined in a plane shape with a floating body used in an embodiment of the apparatus of the present invention.

[Explanation of symbols]

 1 Water Area 10 Extracted Plants 11 Floating Plants 20 Floating Islands 21 Suspended Objects 22 Pumped-up Aerators 30 Light-shielding Sheets 50 Light-blocking Sheets 50a Synthetic Resin Sheets 50b Light-Reflecting Films 50c Reinforcing Wires 51 Engaging Metal Fittings 52 Floating Bodies 52a Engaging Parts 53 Rope

Claims (8)

[Claims] 1. A growth inhibitor for phytoplankton, characterized in that a light blocker is provided on or in the surface of the water body, which covers 1/3 to 2/3 of the total water volume of the water body. Method. 2. The light shield is a living body.
A method for suppressing the growth of phytoplankton according to the description. 3. The method for inhibiting the growth of phytoplankton according to claim 2, wherein the organism is water hyacinth, duckweed or duckweed, or a mixture thereof. 4. The method for suppressing the growth of phytoplankton according to claim 1, wherein the light blocker is an artificial structure. 5. The method for inhibiting the growth of phytoplankton according to claim 5, wherein the artificial structure is Acquiada or hydroponic plant Ikada. 6. The method for suppressing the growth of phytoplankton according to claim 1, wherein the light shield is a light shield sheet. 7. A light shielding sheet, and a floating body detachably attached to each corner of the light shielding sheet and capable of floating on the surface of a water body. A plurality of light shielding sheets are provided through the floating bodies. A phytoplankton growth inhibitory device characterized by being configured so as to be connected in a plane. 8. The phytoplankton growth suppressing apparatus according to claim 7, wherein a reinforcing wire is arranged on each side connecting the corner portions of the light shielding sheet.