JP2010213578A - Artificial floating island - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an artificial floating island effectively suppressing proliferation of phytoplankton to increase a water quality-purifying function, even if the artificial floating island area ratio to a water area is small. <P>SOLUTION: This artificial floating island 1 includes a vegetation base 10, and support means 20 and 30 supporting in a condition of floating the vegetation base 10 in water. Emerging plants 40 which emit an allelopathic agent suppressing proliferation of phytoplankton are planted on the vegetation base 10. The artificial floating island 1 suppresses proliferation of phytoplankton to purify water quality by the artificial floating island of an about 5% area to a water area, by, in addition to a shading function, a function effectively suppressing proliferation of Microcystis of blue-green algae as a cause of generation of water-bloom by allelopathic agent emitted from the root stems 41 of the emerging plants 40 planted on the vegetation base 10 of the artificial floating island 1, an adhesion, contact sedimentation function of phytoplankton and suspended solid to the porous vegetation base of a large specific surface area, and a purifying function multiple with a predation function of phytoplankton through an increase in zooplankton. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique for purifying water quality by suppressing the growth of phytoplankton using an artificial floating island grown with plants.

  Conventionally, a technique using a planted artificial floating island has been known as a method for purifying water quality such as lakes.

  The extraction plants to be planted on this kind of artificial floating islands are selected depending on whether they can be collected in the landscape or basin, and specifically, Kishibu, Hanashobu, Oyster fly, Sekisho, Yoshi, Gama, Mikuri, etc. are preferably used. It has been.

  Conventionally, the structure of this type of artificial floating island is classified into two types: a structure in which a floating body (float) and a vegetation base are separated or a structure in which they are integrated. Among these, the structure having the floating body and the vegetation base separated is provided with a frame-like float of a material that floats on a hollow pipe or water around the vegetation base, for example, as disclosed in Patent Document 1 below, By installing a net on this float and supporting the vegetation base in the float, or as disclosed in Patent Document 2 below, soil or palm fiber on a floating body such as foamed polystyrene or a hollow concrete box A method of providing a vegetation base such as is known.

  As a method of integrating the float and the vegetation base, for example, as in Non-Patent Documents 1 and 2 below, a method of installing a float such as polystyrene foam in a lightweight vegetation base such as palm fiber is known.

JP 7-79652 A JP-A-6-343358

Brochure “Biocosmo”, Zeniya Marine Service Co., Ltd. Brochure “Biosis Island”, Tosco Corporation, April 2000

  However, the conventional phytoplankton growth suppression function by artificial floating islands mainly uses the light shielding effect by shielding the water surface, and the water quality including phytoplankton growth suppression for plant types and vegetation infrastructure The purification function was not fully considered. For this reason, in order to effectively suppress the growth of phytoplankton such as lakes, an artificial floating island having an area of 15 to 30% or more of the water area is necessary.

  In addition, since many of the conventional artificial floating islands have a structure in which the vegetation base is exposed from the water surface, the surface of the vegetation base becomes hot in the summer, which may adversely affect the growth of the extraction plant. Alternatively, in the case of the structure as disclosed in Patent Document 1, the water temperature on the surface of the vegetation base surrounded by the float rises in summer, which may adversely affect the growth of the plant.

  The present invention has been made in view of the above points, and its technical problem is to effectively suppress the growth of phytoplankton even if the area ratio of the artificial floating island to the water area is small. The purpose is to provide an artificial floating island capable of enhancing the water purification function.

  As means for effectively solving the above technical problem, the artificial floating island according to the invention of claim 1 is an artificial floating island comprising a vegetation base and a support means for supporting the vegetation base in a state of floating in water. And the extraction plant which discharge | releases the allelopathic substance which suppresses the proliferation of phytoplankton was planted on the said vegetation base. The allelopathic substance here has the action of suppressing the growth of the blue-green algae Microcystis that causes the occurrence of blue sea cucumber, and, according to the inventor's research, in particular, Higama, Yoshi, Kusayoshi, Makomo, Futoi, Kangarei, It has been confirmed that an allelopathic substance released by a water-drawing plant selected from oyster grasshopper, honeybee, and sedge is effective in suppressing the growth of Microcystis.

  An artificial floating island according to a second aspect of the present invention is characterized in that, in the configuration according to the first aspect, the supporting means comprises a required number of floats.

  An artificial floating island according to a third aspect of the invention is characterized in that, in the configuration of the first aspect, the support means comprises a tether or tether that anchors the vegetation base and the bottom of the water.

The artificial floating island according to the invention of claim 4 is the structure according to claim 1, wherein the vegetation base is a three-dimensional network structure, the specific surface area is 1,000 to 2,000 m ² / m ³ , and the continuous porosity is 80% or more. It consists of a porous material.

  The artificial floating island according to the invention of claim 5 is characterized in that, in the configuration of claim 1, the vegetation base is formed to a thickness of 7.5 to 20 cm.

  The artificial floating island according to the invention of claim 6 is the structure according to claim 1, wherein the vegetation base is submerged so that the surface has a water depth of 5 cm to 15 cm, and water can flow on the vegetation base. It is a feature.

  The artificial floating island according to the invention of claim 7 is characterized in that, in the configuration of claim 1, the vegetation base is supported by a support having a structure in which a net is stretched on a frame fixed to the support means. It is.

  The artificial floating island according to the invention of claim 8 is the structure according to claim 1, wherein the planting of the extraction plant on the vegetation base is a seedling planted in soil filled in a pot made of woven fabric or nonwoven fabric. It is characterized by being made by installing a pot seedling on the vegetation base.

  According to the artificial floating island according to the inventions of claims 1 to 3, in addition to the light-shielding function by the artificial floating island, the allelopathic substance released from the rhizomes of the extracted plants planted on the vegetation base of the artificial floating island, Because the growth of the green cyanobacterium Microcystis is effectively suppressed, the water quality can be purified.

According to the artificial floating island according to the invention of claim 4, the vegetation base is a three-dimensional network structure made of a porous material having a specific surface area of 1,000 to 2,000 m ² / m ³ and a continuous porosity of 80% or more. Since the rhizome of the extracted plant is easy to develop, the allelopathic substance generated from the rhizome is easily released into the water, and the water easily comes into contact with the rhizome. Therefore, the effect according to claim 1 can be improved. In addition, phytoplankton and suspended solids adherence, contact sedimentation function, and phytoplankton predation function due to the increase of zooplankton are obtained. It is an artificial floating island with an area of about 1/6 to 1/3) of that of artificial floating islands, and it can purify water quality by suppressing the growth of phytoplankton.

  According to the artificial floating island according to the invention of claim 5, by forming the vegetation base to a thickness of 7.5 to 20 cm, it becomes suitable for the growth of the extraction plant in which the underground stem develops to form a community, Since it is suitable for the contact precipitation effect of phytoplankton and the increase of zooplankton that prey on phytoplankton, the effect according to claim 1 can be improved.

  According to the artificial floating island according to the invention of claim 6, the vegetation base is submerged so that the surface has a water depth of 5 cm to 15 cm and water can be distributed on the vegetation base, so that the vegetation base in summer or While suppressing the rise in surface water temperature and preventing the growth inhibition of the extraction plant due to overgrowth of land weeds, the effect of claim 1 can be improved.

  According to the artificial floating island according to the invention of claim 7, the vegetation base is supported by the support having a structure in which a net is stretched on a frame fixed to the support means, thereby including a suspension such as phytoplankton. The water can be efficiently contacted with the vegetation base material, and the allelopathic substance is easily released into the water, and the suspension aggregates on the surface of the vegetation base material and aggregates to a size that tends to settle. Since it can be made to promote, the effect by Claim 1 can be improved.

  According to the artificial floating island according to the invention of claim 8, the seedling stock of the extraction plant can easily grow, so the effect of claim 1 can be improved.

It is a top view which shows the 1st form of the artificial floating island which concerns on this invention. It is II-II 'sectional drawing of FIG. FIG. 3 is a sectional view taken along the line III-III ′ of FIG. 1. It is explanatory drawing which shows the planting method of the seedling stock of the extraction plant to a vegetation base. It is a top view which shows the 2nd form of the artificial floating island which concerns on this invention. FIG. 6 is a V-V ′ sectional view of FIG. 5. It is a top view which shows the 3rd form of the artificial floating island which concerns on this invention. It is VII-VII 'sectional drawing of FIG. It is VIII-VIII 'sectional drawing of FIG. It is a top view which shows the 4th form of the artificial floating island which concerns on this invention. It is a top view which shows the 5th form of the artificial floating island which concerns on this invention. It is explanatory drawing which shows the method of the laboratory test for confirming the allelopathic effect by a water extraction plant. It is explanatory drawing which shows the result of the laboratory test for confirming the allelopathic effect. It is explanatory drawing which shows the result of the field survey for confirming the allelopathic effect. It is explanatory drawing which shows the result of the outdoor cultivation test for grasping | ascertaining the influence which the presence or absence of soil has on the growth of a extraction plant at the time of planting the seedling stock of an extraction plant. It is explanatory drawing which shows the result of the test by the field investigation for grasping | ascertaining the influence which the presence or absence of soil has on the growth of a extraction plant at the time of planting the seedling of a extraction plant. It is explanatory drawing which shows the result of having investigated the new deposit under the artificial floating island by a field survey. It is explanatory drawing which shows the result of having investigated the new deposit under the artificial floating island by a field survey. It is explanatory drawing which shows the result of having carried out the field survey about the increase in the zooplankton with the predation and decomposition | disassembly effect of phytoplankton. It is explanatory drawing which shows the time-dependent change of Chl-a density | concentration after the start of the verification test by the artificial floating island of this invention.

  Hereinafter, a preferred embodiment of an artificial floating island according to the present invention will be described in detail with reference to the drawings. First, FIGS. 1 to 3 show a first embodiment.

  As shown in FIGS. 1 to 3, the artificial floating island 1 according to the first embodiment includes a vegetation base 10, a float 20 composed of a floating float 21 and an underwater float 22 for floating the vegetation base 10 in water, and the float 20. It consists of the fixing member 30 which connects the to the vegetation base 10. That is, the vegetation base 10 is supported in a state of floating in the water W at an appropriate water depth d (see FIG. 3) by the floating float 21 and the underwater float 22 through the fixing member 30. An extraction plant 40 that releases an allelopathic substance that suppresses the growth of plankton is planted.

  Effective actions for water purification by the artificial floating island 1 are not only shading action, but also allelopathic action by the extraction plant 40 planted on the vegetation base 10, contact sedimentation action of suspended substances such as phytoplankton, and increase of zooplankton. Phytoplankton predation and decomposition action.

  In order to maximize these effects, in the present invention, a water extraction plant 40 that releases an allelopathic substance that suppresses the growth of the blue-green algae Microcystis, which is a cause of the occurrence of blue-green algae, is selected and planted on the vegetation base 10. Examples of the extraction plant 40 having an allelopathic effect that suppresses the growth of Microcystis include Higama, Yoshi, Kusayoshi, Makomo, Futoi, Kangarei, Oyster-beetle, Hanashobu, Kasa-suge, etc. Cultivate and use it in possible fields or in fields.

By using a porous material with a large specific surface area as the vegetation base 10, the area to which suspended substances in water adhere increases, and the attached suspension aggregates to a size that facilitates sedimentation, thus promoting sedimentation. can do. Specifically, the vegetation base 10 has a mat surface made of polyester or vinyl chloride fibers having a specific surface area of 1,000 to 2,000 m ² / m ³ , a continuous porosity of 80% or more, and high weather resistance. Use things.

  In addition, as shown in FIG. 4, planting of the extraction plant 40 on the vegetation base 10 is performed by filling a pot 11 made of woven fabric or non-woven fabric with soil 12 made of commercially available horticultural soil or the like. This is done by planting a seedling 40a of a water-drawing plant and installing it on a vegetation base 10 vertically and horizontally as shown in FIG. This is because planting using the pot 11 significantly improves the survival rate of the vegetation base 10. As shown in FIGS. 2 and 3, the planted water extraction plant 40 can have the rhizome 41 extending from the vegetation 11 to the vegetation base 10 and further from the vegetation base 10 to the water.

Here, when the continuous porosity of the vegetation base 10 is less than 80% or the pore size is too fine, the sedimented sludge accumulates in the vegetation base 10 and causes clogging. By setting the ratio to 80% or more, accumulation of sludge in the vegetation base 10 can be prevented, and the contact efficiency with the water W can be maintained. Moreover, considering the fiber strength that can secure a continuous porosity of 80% or more and the strength of the vegetation base 10 can withstand the lodging of the extraction plant 40, the amount of resin of the vegetation base 10 needs to be 16 kg / m ³ or more. . In this case, the specific surface area is 1,000 m ² / m ³ . In other words, when the specific surface area is less than 1,000 m ² / m ³ , the vegetation base 10 is too soft and the grown extracted plant 40 may fall down due to wind load. On the other hand, if the specific surface area exceeds 2,000 m ² / m ³ , the continuous void size of the vegetation base 10 becomes too fine, and the suspended matter is easily clogged. Therefore, a vegetation base 10 having a specific surface area of 1,000 to 2,000 m ² / m ³ and a continuous porosity of 80% or more is used.

  The float 20 (water float 21 and water float 22) is formed of, for example, a pipe made of vinyl chloride or a pipe made of fiber reinforced plastic, and has a sufficiently high buoyancy because it is hollow. ing. Among these, as shown in FIG. 1, a pair of water floats 21 having a length substantially equal to the length of the vegetation base 10 having a square shape or a rectangular shape is disposed along two opposite sides. The underwater floats 22 extend so as to be substantially orthogonal to the overwater float 21, and as shown in FIG. 2 and FIG.

  The fixing member 30 is a hot-dip galvanized steel outer peripheral frame 31 that supports the outer peripheral portion of the vegetation base 10, and is flatly stretched on the lower surface of the outer peripheral frame 31, and is made of synthetic resin such as polyethylene or rust-proof steel. A net 32 made of steel or stainless steel and having a mesh size of 25 to 100 mm, and a required number of beam-like frames 33 made of hot-dip galvanized steel installed on the lower surface of the outer peripheral frame 31 so as not to bend downward. A water float mounting member 34 made of hot dip galvanized steel for attaching the water float 21 to the outer peripheral frame 31, and a water float mounting member 35 made of hot dip galvanized steel for attaching the water float 22 to the lower side of the beam frame 33. . Then, by supporting the vegetation base 10 with the fixing member 30 having such a structure, the vegetation base 10 is installed in a state of being submerged in water, and the water W including suspensions such as phytoplankton is efficiently supplied to the vegetation base 10. Can be touched.

  Further, since the water W in the water area to be purified can freely circulate on the vegetation base 10 from the side where the water float 21 is not disposed, suspended substances such as underwater phytoplankton can be present on the surface of the vegetation base 10. And the action of adhering to and sinking to the brewed extraction plant 40 is promoted.

  Preferably, the upper surface of the vegetation base 10 has a water depth of 5 to 15 cm. This is because when the water depth d exceeds 15 cm, the growth of the extraction plant 40 tends to be adversely affected. When the water depth d is less than 5 cm, the water W hardly flows on the upper surface of the vegetation base 10, and suspended substances such as phytoplankton in the water are present. This is because there is a possibility that the action of sinking to the vegetation base 10 and adhering / sinking to the extraction plant 40 may not be obtained, or the water temperature on the vegetation base 10 may rise in summer and adversely affect the growth of the extraction plant 40.

  According to the artificial floating island 1 of the first form having the above-described configuration, by abnormal growth of phytoplankton such as Microcystis of the blue-green algae in closed waters such as natural lakes, ponds, city parks, The water quality can be efficiently purified in the situation where the water quality is polluted. This is because the allelopathic substance released into the water from the rhizome 41 of the extraction plant 40 planted on the vegetation base 10 suppresses the growth of the phytoplankton such as the Microcystis, and the suspended substance such as the phytoplankton suppresses the vegetation base. This is because it settles down to 10 and adheres to and settles on the extracted water plant 40, and therefore, the occurrence of blue sea bream is suppressed. In addition, zooplankton such as daphnia and rotifers and bacteria inhabit the surface and voids of the vegetation base 10 composed of a three-dimensional network structure having a large specific surface area, and these micro-animals prey on and decompose phytoplankton. This is because the function is improved.

  Therefore, even in the artificial floating island 1 having an area of 5% to 10% of the water area of the closed water area to be purified, the transparency can be improved, organic pollution can be prevented, and the nutrient salt concentration can be reduced.

  Next, FIG.5 and FIG.6 shows the 2nd form of the artificial floating island which concerns on this invention. The artificial floating island 1 according to the second embodiment also includes a vegetation base 10, a float 20 that floats the vegetation base 10 on the water W, and a fixing member 30 that connects the float 20 to the vegetation base 10. That is, the vegetation base 10 is supported by the float 20 through the fixing member 30 in a state of floating in the water W at an appropriate water depth, and the vegetation base 10 releases an allelopathic substance that suppresses the growth of phytoplankton. The extraction plant 40 is planted.

  The float 20 is composed of a water float 23 and a water float 24 extending in a frame shape along the outer peripheral edge of the vegetation base 10, and is coupled to each other by a band 25 at an appropriate interval in the vertical direction.

  As shown in FIG. 6, a car 36 formed of a hard net is attached to the underwater float 24 as a fixing member 30, and the vegetation base 10 is installed in the car 36. In other words, the vegetation base 10 is supported by the buoyancy of the float 20 through the cage 36, so that the vegetation base 10 is installed in a state where it is submerged in water, and the water W containing suspended matter such as phytoplankton is efficiently supplied. It can come into contact with the vegetation base 10.

  In this case, as shown in FIG. 6, the underwater float 24 is submerged, and the water W in the water area to be purified freely circulates on the vegetation base 10 from the gap δ between the underwater float 23. In this case as well, the upper surface of the vegetation base 10 is set to 5 to 15 cm below the water surface. For this reason, while suspended substances, such as underwater phytoplankton, settle on the surface of the vegetation base 10, the effect | action which adheres and settles to the overgrown extraction plant 40 is accelerated | stimulated.

  In addition, the vegetation base 10 is the same as that of the 1st form demonstrated previously, The planting method of the extraction plant 40, etc. can be performed similarly to a 1st form. Therefore, the same operation and effect as the first embodiment can be realized.

  Next, FIGS. 7 to 9 show a third embodiment of the artificial floating island according to the present invention. The third embodiment is different from the first embodiment described above in that the floating float 21 in the float 20 is arranged in the vicinity of the four corners of the vegetation base 10 having a square or rectangular planar shape. The configuration of the other parts is basically substantially the same as that of the first embodiment, and the same operations and effects as those of the first embodiment can be realized.

  Next, FIG. 10 shows a fourth embodiment of the artificial floating island according to the present invention. In each of the above-mentioned forms, the float 20 is composed of the water float 21 (23) and the underwater float 22 (24), whereas in the fourth form, the float 20 is composed of only the underwater float 22, and the bottom of the water (pond or An appropriate depth of water d (destination) is provided via a anchor 50 comprising an anchor 51 driven into the bottom of the swamp G and a anchoring rope 52 having a lower end connected to the anchor 51 and an upper end connected to the fixing member 30. As described in (5), it is anchored in a state of floating in the water W at 5 to 15 cm). Other parts can be configured basically in the same manner as the first embodiment.

  FIG. 11 shows a fifth embodiment of the artificial floating island according to the present invention. In this embodiment, instead of the anchor 50 in the fourth embodiment, the anchor pile 60 driven into the bottom G is anchored in a state floating in the water W at an appropriate water depth d through the vegetation base 10. . Other parts can be configured basically in the same manner as the first embodiment.

  And according to these 4th or 5th form, since the floating height from the bottom G is kept constant by the anchor 50 or the anchor pile 60, in the pond marsh where the water level is constant, the upper surface of the vegetation base 10 It can be suitably employed as means for keeping the water depth d constant.

  Various verification tests for confirming the effect of the artificial floating island of the present invention were conducted, and will be described below.

Demonstration test 1:
Laboratory tests were conducted to confirm the allelopathic effect of the extracted plants. In this test, ten kinds of water extraction plants were used: kishobu, hanashobu, oyster beetle, ginger, kangarei, futoi, kusayoshi, makomo, matsukasusuki, and himegama.

  As shown in FIG. 12, the test method is as follows. Water 103 is placed in a bucket 101, a vegetation base 102 is set on the bucket 101, and after the water-drawn plant 104 is cultivated by pot planting, the bucket 101 and the vegetation base 102 are After washing, the medium (water 103) in the bucket 101 was replaced and cultivated in a greenhouse for one week. One week later, using water obtained by filtering the water 103 with a 0.25 μm filter paper, the specific growth rate of Microcystis, a blue-forming blue-green algae, was confirmed by bioassay method. did.

  As a result of this test, as shown in FIG. 13, the specific growth rate of the blue-green algae is compared with a control plant that has been confirmed not to have an allelopathic effect in water cultivated by Matsukasusuki, Kshobu, and Sekisho. Although no significant decrease was observed, it was confirmed that the specific growth rate was significantly decreased in water cultivated with chickpeas, cedars, hanashobu, futoi, makomo, oyster butterflies and flounder. In particular, Futui was found to have a remarkable allelopathic effect.

Demonstration test 2:
A field test was conducted to confirm the allelopathic effect of the extracted plants. The test methods are: near the rhizomes of the artificial floating island extraction plants installed in the isolated water area (1,000 m ² , average water depth: about 1.2 m) installed in Yamano Kanuma, Hasuda City, in the isolated water area without artificial floating islands, and Water was collected from a pond swamp outside the isolated water area, and the growth inhibition effect by allelopathy was confirmed by investigating the specific growth rate of Microcystis, a blue-forming blue-green algae, using the bioassay method as in Example 1. As artificial floating islands, four types of artificial floating islands were used: those planted with reeds, those planted with himegama, those planted with macomo, and those planted with maggots.

  As a result of this test, as shown in FIG. 14, the allelopathic effect was confirmed in any of the artificial floating islands planted with four kinds of extraction plants, and no effect was seen in the water area without artificial floating islands or outside the isolated water. . And among these four kinds of water-drawing plants, the result that maggot has the largest allelopathic effect was obtained.

Demonstration test 3
In order to investigate the thickness of the vegetation base suitable for the development of rhizomes, a square (30 mx 30 cm) with a thickness of 10 cm, 15 centimeters and 20 centimeters in a pool (2 mx 3 m, water depth of about 50 cm) installed outdoors A pot of extracted water plants was planted on the vegetation base of, and a cultivation test was conducted. There were five types of water extraction plants: Kangarei, Futoi, Yoshi, Himegama, and Makomo.

  As a result of the test, the rhizomes of the extracted plants are seen from the side of the vegetation base, depending on the type, and the depth from the vegetation base surface is 12-15 cm for Yoshi, 10-15 cm for Himega, and 5-16 cm for Makomo. Now we know that the rhizomes grow. That is, it was found from the test results that the rhizomes of the extracted water plants in which the rhizomes develop are distributed at a depth of 5 cm to 16 cm. Therefore, it was confirmed that the thickness of the vegetation base is preferably about 7.5 cm (more than the size of the plant pot seedling) to 20 cm (the depth at which the basement stem develops) depending on the type of plant.

Demonstration test 4:
When planting the seedlings of the extraction plant, an outdoor cultivation test was conducted to grasp the effect of the presence or absence of soil on the growth of the extraction plant. The test method consists of an outdoor pool (2m x 3m, depth of water: about 50cm), a pot seedling planted with a seedling of a water extraction plant in a palm fiber pot filled with soil, and a seedling plant without a pot and soil. Each was placed on a vegetation base material and the growth of seedlings was measured. Four kinds of water extraction plants were kangarei, futoi, macomo, and kishobu.

  As a result of the test, when the dry weight (average value of each of the two strains) of the plant body after two years passed after planting was measured, the seedling planted by filling the palm pot with soil and planting as shown in FIG. Compared to the case without soil, the growth of both the above-ground part and the rhizome was significantly different, and it was confirmed that the soil pot was effective for the seedlings.

Demonstration test 5:
In addition, when planting the seedlings of the extraction plant on the floating vegetation island in the actual pond marsh, a field survey was conducted to confirm whether the presence or absence of soil was effective for the growth of the extraction plant. In this test, we investigated the survival rate of water-drawn plants on artificial floating islands installed in the isolated water field (1,000 m ² , average water depth: about 1.2 m) installed in Yamano Kanuma, Hasuda City. As artificial floating islands, four types of artificial floating islands were used: those planted with reeds, those planted with himegama, those planted with macomo, and those planted with maggots.

  As a result of the test, as shown in FIG. 16, all four kinds of extracted plants have a better survival rate when planted in a soil pot, and those that do not use soil have extremely worsening survival rates of plants other than Makomo. I understood.

Demonstration test 6:
Five isolated water areas (15m ² ) closed with a water shielding sheet are installed in Yamanokami Marsh, Hasuda City, where edible mud is deposited and microalgae (dominant species Chroococcus sp.) Grow abnormally. the isolation waters, as shown in Table 1, different artificial floating island (1.5 m ^2/1 group) established the (artificial the floating island specific surface area 1,556m ² / m ^3, 98% continuous porosity of the structure, the thickness of the The vegetation base made of polyester of 7.5 cm and 15 cm was used), and the new deposits under each artificial floating island were investigated. The survey of new deposits was conducted twice a week for about two months, and was measured from the difference between the water quality in the sediment trap and the water quality in the isolated water field collected at the time of the survey.

Since the new sediment velocity is strongly influenced by water quality, the ratio of the water quality to the sediment velocity is expressed as the sediment velocity index SVI (water quality (g · m ⁻³ ) / sediment velocity (g · m ⁻² · d ^-1 ): The number of days required to deposit a unit amount of water (d · m ^-1 )) was evaluated for the sedimentation promoting effect of suspended solids due to the difference in floating island structure. As a result, the relationship between the SVI of SS (suspended material) and Chl-a (chlorophyll-a) and the concentration in the isolated water boundary is shown in FIG. 17 and FIG. , SS and Chl-a were reduced in SVI in the 2nd to 5th districts compared to the case without artificial floating island (1st district), and the sedimentation promoting effect was seen. In particular, the SVI reduction effect of the suspended contact material (5 wards) was high. In the 2nd to 4th districts where the artificial floating island uses a vegetation base made of porous resin mat, the SVI reduction effect of the 4th ward with the vegetation base installed on the water surface was high for SS, but Chl-a was submerged 2 The SVI reduction effect was high in the 3rd and 3rd wards. In addition, the 3 wards with a vegetation base thickness of 15 cm had slightly higher SVI reduction effects than the 2 wards of 7.5 cm, but no significant difference was observed.

In other words, when artificial floating islands with a vegetation base thickness of 7.5 cm or 15 cm were installed, the rate of newly formed sediments increased compared to the isolated water area without artificial floating islands (1 ward), but the vegetation base thickness Despite being twice as large, there was no significant difference in the nascent sediment rate. Therefore, the density (specific surface area) of the vegetation base and the thickness of the vegetation base are such that even if the base density per unit area is too high, suspended matter accumulates in the base and contact precipitation is less likely to occur. It was confirmed that the effect was reduced even if the hit base density was too low. From this, it is considered that 1,000-2,000 m ² / m ³ is appropriate for the specific surface area of the vegetation base, and it is not necessary to consider when the thickness of the vegetation base exceeds 7.5 cm.

Demonstration test 7:
In addition, we examined the predation and decomposition effects of phytoplankton due to the increase of zooplankton. As the method, the following isolated water areas (1,000 m ² ) are set up in Yamano Kanuma in Hasuda City, and the thickness of the vegetation base and planting conditions are set for 2 wards to 5 wards. The polyester porous mat (specific surface area 1,556m ² / m ³ , continuous porosity 98%, 45cm x 50cm) is installed so that the water depth on the surface of the vegetation base is about 5cm and collected in the summer after about one year Then, the zooplankton in the vegetation base was washed out, and the total amount of zooplankton collected by the plankton net of 0.1 mm was quantitatively analyzed to investigate the difference in the existing amount of zooplankton depending on the thickness of the vegetation base and the presence or absence of plants. .
1st ward: No floating island 2nd ward: 75mm thick vegetation base 3rd ward: 150mm thick vegetation base 4th ward: 75mm thick vegetation base 5th vegetation planting 5th ward: 75mm thick vegetation base, 4th reed planting

  As a result of the investigation, as shown in FIG. 19, zooplankton both in the type and the number of individuals increased significantly in the vegetation base of the artificial floating island compared to the water area (1st ward) where there was no artificial floating island. In addition, when the thickness of the vegetation base is 75mm (2nd ward) and 150mm (3rd ward), there is no big difference in the total population density. There was a tendency to increase the number. Those planted with reeds and makomo may have reduced the volume of the seedling pot and the volume of the vegetation base. It was.

  In order to confirm the effect of the artificial floating island of the present invention, a demonstration test using a small isolated water field was carried out in Yamano Kanuma, Hasuda City, Saitama Prefecture, which is a eutrophic pond swamp predominated by the blue-green algae Microcystis. Here, the knowledge acquired about the presence or absence of an extraction plant, a planting seed | species, and the shielding rate of the artificial floating island (ratio of the area of the artificial floating island with respect to a water area) and the growth inhibitory effect of a phytoplankton is shown.

Nine isolated water boundaries (3.87m x 3.87m = 15m ² , approximately 1m water depth) are placed in Yamanojinuma, and no artificial floating islands are installed in each isolated water boundary as shown in Table 2. In addition to the ward, from August 9th to November 3rd, 2008, a test ward with artificial floating islands with different shielding rates and planting species was established. Among the planting species, as described in the verification test 1 described above, Makomo and Higama are plants having an allelopathic effect, and citrus is a plant having no allelopathic effect.

In addition, the vegetation base of the artificial floating island was installed so that the surface water depth might be 5-10 cm. The vegetation-based porous material is a polyester three-dimensional network structure with a specific surface area of 1,556 m ² / m ³ and a continuous porosity of 98%. In order to cause poor growth when the soil pot was planted in a soil pot, only seedlings were planted directly on the vegetation base.

  In each test zone, water flowed in and out of isolated water due to fluctuations in the water level of Yamanokami Marsh. The water exchange rate in the isolated water area due to the fluctuation of the water level from September 5 to November 3 when the water level was stabilized after the isolated water field was submerged due to heavy rain was 1.5% on average per day.

  FIG. 20 shows the change over time in the Chl-a concentration after the start of the verification test. As can be seen from Fig. 20, the 2nd and 3rd ward where the artificial floating islands that are not planted were installed showed a decreasing tendency compared to the one without the floating island (1st ward). The Chl-a concentration was reduced from the vegetation base with a shielding rate of 5%. In addition, when comparing the test plots with the same shielding rate, the test plots planted with Makomo and Himegama, which have the allelopathic effect, have lower Chl-a concentrations than the second and third plots where artificial floating islands are not planted. In addition, the results showed that the growth of phytoplankton could be suppressed even on an artificial floating island with a vegetation base with a shielding rate of 5%. On the other hand, the 8th and 9th districts where the artificial floating islands planted with buffets without allelopathic effects were installed had a shielding rate of 5% (8th district) compared to the 2nd and 3rd districts where the artificial floating islands were not planted. There was no significant difference, and an increasing trend was seen at a shielding rate of 10% (9 districts).

  Therefore, as a result of this verification test, if artificial floating islands planted with the water-blowing makomo and chickpea that have the allelopathic effect are used, the vegetation substrate adhesion and contact sedimentation effects confirmed in verification test 6 and Due to the combined effects of phytoplankton predation and decomposition due to the increase in zooplankton confirmed in Test 7, the area of the artificial floating island (shielding rate) is 5% of the water area, in other words, 1 of the conventional artificial floating island It was confirmed that the growth of phytoplankton can be suppressed even in an area of about / 6 to 1/3.

DESCRIPTION OF SYMBOLS 1 Artificial floating island 10 Vegetation base 20 Float 21,23 Water float 22,24 Underwater float 30 Fixing member 40 Extraction plant 41 Rhizome 50 Tether 60 Tethered pile

As a means for effectively solving the above technical problem, an artificial floating island according to the invention of claim 1 is a vegetation base made of a porous material having a three-dimensional network structure, and the vegetation base is floated in water. An artificial floating island composed of supporting means for supporting, characterized in that an extraction plant that releases an allelopathic substance that suppresses the growth of phytoplankton is planted on the vegetation base. The allelopathic substance here has the action of suppressing the growth of the blue-green algae Microcystis that causes the occurrence of blue sea cucumber, and, according to the inventor's research, in particular, Higama, Yoshi, Kusayoshi, Makomo, Futoi, Kangarei, It has been confirmed that an allelopathic substance released by a water-drawing plant selected from oyster grasshopper, honeybee, and sedge is effective in suppressing the growth of Microcystis.

The artificial floating island according to the invention of claim 4 is characterized in that, in the configuration of claim 1, the vegetation base is formed to a thickness of 7.5 to 20 cm.

The artificial floating island according to the invention of claim 5 is characterized in that, in the configuration according to claim 1, the vegetation base is submerged so that the surface has a water depth of 5 cm to 15 cm and water can flow on the vegetation base. It is a feature.

An artificial floating island according to the invention of claim 6 is characterized in that, in the configuration of claim 1, the vegetation base is supported by a support having a structure in which a net is attached to a frame fixed to the support means. It is.

The artificial floating island according to the invention of claim 7 is the structure according to claim 1, wherein the planting of the extraction plant on the vegetation base is made by planting a seedling in soil filled in a pot made of woven fabric or non-woven fabric. It is characterized by being made by installing a pot seedling on the vegetation base.

In addition, because the vegetation base has a three-dimensional network structure made of a porous material, the rhizomes of the extracted plants are easy to develop, the allelopathic substances generated from the rhizomes are easily released into the water, and the water easily comes into contact with the rhizomes. The effect of claim 1 can be improved. In addition, phytoplankton and suspended solids adherence, contact sedimentation function, and phytoplankton predation function due to the increase of zooplankton are obtained. It is an artificial floating island with an area of about 1/6 to 1/3) of that of artificial floating islands, and it can purify water quality by suppressing the growth of phytoplankton.

According to the artificial floating island according to the invention of claim 4 , by forming the vegetation base to a thickness of 7.5 to 20 cm, it becomes suitable for the growth of the extraction plant in which the underground stem develops to form a community, Since it is suitable for the contact precipitation effect of phytoplankton and the increase of zooplankton that prey on phytoplankton, the effect according to claim 1 can be improved.

According to the artificial floating island according to the invention of claim 5 , the vegetation base is submerged so that its surface has a water depth of 5 cm to 15 cm and water can be distributed on the vegetation base, so that the vegetation base in summer or While suppressing the rise in surface water temperature and preventing the growth inhibition of the extraction plant due to overgrowth of land weeds, the effect of claim 1 can be improved.

According to the artificial floating island according to the invention of claim 6 , the vegetation base is supported by the support having a structure in which a net is stretched on a frame fixed to the support means, thereby including a suspension such as phytoplankton. The water can be efficiently contacted with the vegetation base material, and the allelopathic substance is easily released into the water, and the suspension aggregates on the surface of the vegetation base material and aggregates to a size that tends to settle. Since it can be made to promote, the effect by Claim 1 can be improved.

According to the artificial floating island according to the invention of claim 7 , the seedling stock of the extraction plant can easily grow, so the effect of claim 1 can be improved.

  The present invention relates to a technique for purifying water quality by suppressing the growth of phytoplankton using an artificial floating island grown with plants.

  Conventionally, a technique using a planted artificial floating island has been known as a method for purifying water quality such as lakes.

  The extraction plants to be planted on this kind of artificial floating islands are selected depending on whether they can be collected in the landscape or basin, and specifically, Kishibu, Hanashobu, Oyster fly, Sekisho, Yoshi, Gama, Mikuri, etc. are preferably used. It has been.

  Conventionally, the structure of this type of artificial floating island is classified into two types: a structure in which a floating body (float) and a vegetation base are separated or a structure in which they are integrated. Among these, the structure having the floating body and the vegetation base separated is provided with a frame-like float of a material that floats on a hollow pipe or water around the vegetation base, for example, as disclosed in Patent Document 1 below, By installing a net on this float and supporting the vegetation base in the float, or as disclosed in Patent Document 2 below, soil or palm fiber on a floating body such as foamed polystyrene or a hollow concrete box A method of providing a vegetation base such as is known.

  As a method of integrating the float and the vegetation base, for example, as in Non-Patent Documents 1 and 2 below, a method of installing a float such as polystyrene foam in a lightweight vegetation base such as palm fiber is known.

JP 7-79652 A JP-A-6-343358

Brochure “Biocosmo”, Zeniya Marine Service Co., Ltd. Brochure “Biosis Island”, Tosco Corporation, April 2000

  However, the conventional phytoplankton growth suppression function by artificial floating islands mainly uses the light shielding effect by shielding the water surface, and the water quality including phytoplankton growth suppression for plant types and vegetation infrastructure The purification function was not fully considered. For this reason, in order to effectively suppress the growth of phytoplankton such as lakes, an artificial floating island having an area of 15 to 30% or more of the water area is necessary.

  In addition, since many of the conventional artificial floating islands have a structure in which the vegetation base is exposed from the water surface, the surface of the vegetation base becomes hot in the summer, which may adversely affect the growth of the extraction plant. Alternatively, in the case of the structure as disclosed in Patent Document 1, the water temperature on the surface of the vegetation base surrounded by the float rises in summer, which may adversely affect the growth of the plant.

  The present invention has been made in view of the above points, and its technical problem is to effectively suppress the growth of phytoplankton even if the area ratio of the artificial floating island to the water area is small. The purpose is to provide an artificial floating island capable of enhancing the water purification function.

As a means for effectively solving the above technical problem, an artificial floating island according to the invention of claim 1 is a vegetation base made of a porous material having a three-dimensional network structure, and the vegetation base is floated in water. An artificial floating island comprising supporting means to support, characterized in that a water extraction plant selected from Himegama, Kusasayoshi, Makomo, and Kasasuge which releases an allelopathic substance that suppresses the growth of phytoplankton is planted on the vegetation base. It is what. The allelopathic substance mentioned here has an action of suppressing the growth of the blue-green algae Microcystis that causes the occurrence of blue sea cucumber, and according to the inventor's research, the allelopathic substance released by the above-mentioned Himegama, Kusuyoshi, Makomo, and Kasa-suge It was confirmed to be effective in suppressing the growth of Microcystis.

According to the artificial floating island according to the invention of claim 1 , in addition to the light shielding function by the artificial floating island, a water-drawing plant selected from the ground beetle, kuyoyoshi, makomo, and casserole planted on the vegetation base of the artificial floating island releases from its rhizome. The allelopathic substance effectively suppresses the growth of the blue-green algae Microcystis, which is the cause of the blue-green algae, so that the water quality can be purified.

  In addition, because the vegetation base has a three-dimensional network structure made of a porous material, the rhizomes of the extracted plants are easy to develop, the allelopathic substances generated from the rhizomes are easily released into the water, and the water tends to come into contact with the rhizomes. The effect of claim 1 can be improved. In addition, phytoplankton and suspended solids adherence, contact sedimentation function, and phytoplankton predation function due to the increase of zooplankton are obtained. It is an artificial floating island with an area of about 1/6 to 1/3) that of artificial floating islands in Japan, and it can purify water quality by suppressing the growth of phytoplankton.

It is a top view which shows the 1st form of the artificial floating island which concerns on this invention. It is II-II 'sectional drawing of FIG. FIG. 3 is a sectional view taken along the line III-III ′ of FIG. 1. It is explanatory drawing which shows the planting method of the seedling stock of the extraction plant to a vegetation base. It is a top view which shows the 2nd form of the artificial floating island which concerns on this invention. FIG. 6 is a V-V ′ sectional view of FIG. 5. It is a top view which shows the 3rd form of the artificial floating island which concerns on this invention. It is VII-VII 'sectional drawing of FIG. It is VIII-VIII 'sectional drawing of FIG. It is a top view which shows the 4th form of the artificial floating island which concerns on this invention. It is a top view which shows the 5th form of the artificial floating island which concerns on this invention. It is explanatory drawing which shows the method of the laboratory test for confirming the allelopathic effect by a water extraction plant. It is explanatory drawing which shows the result of the laboratory test for confirming the allelopathic effect. It is explanatory drawing which shows the result of the field survey for confirming the allelopathic effect. It is explanatory drawing which shows the result of the outdoor cultivation test for grasping | ascertaining the influence which the presence or absence of soil has on the growth of a extraction plant at the time of planting the seedling stock of an extraction plant. It is explanatory drawing which shows the result of the test by the field investigation for grasping | ascertaining the influence which the presence or absence of soil has on the growth of a extraction plant at the time of planting the seedling of a extraction plant. It is explanatory drawing which shows the result of having investigated the new deposit under the artificial floating island by a field survey. It is explanatory drawing which shows the result of having investigated the new deposit under the artificial floating island by a field survey. It is explanatory drawing which shows the result of having carried out the field survey about the increase in the zooplankton with the predation / decomposition effect of phytoplankton. It is explanatory drawing which shows the time-dependent change of Chl-a density | concentration after the start of the verification test by the artificial floating island of this invention.

  Hereinafter, a preferred embodiment of an artificial floating island according to the present invention will be described in detail with reference to the drawings. First, FIGS. 1 to 3 show a first embodiment.

  As shown in FIGS. 1 to 3, the artificial floating island 1 according to the first embodiment includes a vegetation base 10, a float 20 composed of a floating float 21 and an underwater float 22 for floating the vegetation base 10 in water, and the float 20. It consists of the fixing member 30 which connects the to the vegetation base 10. That is, the vegetation base 10 is supported in a state of floating in the water W at an appropriate water depth d (see FIG. 3) by the floating float 21 and the underwater float 22 through the fixing member 30. An extraction plant 40 that releases an allelopathic substance that suppresses the growth of plankton is planted.

  Effective actions for water purification by the artificial floating island 1 are not only shading action, but also allelopathic action by the extraction plant 40 planted on the vegetation base 10, contact sedimentation action of suspended substances such as phytoplankton, and increase of zooplankton. Phytoplankton predation and decomposition action.

In order to maximize these effects, in the present invention, a water extraction plant 40 that releases an allelopathic substance that suppresses the growth of the blue-green algae Microcystis, which is a cause of the occurrence of blue-green algae, is selected and planted on the vegetation base 10. As the extraction plant 40 having an allelopathic effect that suppresses the growth of Microcystis, there are himemasa, kuusayoshi, makomo, and maggots . Among these, those that can be obtained and transplanted in the water to be purified, or cultivated in the field, etc. use.

By using a porous material with a large specific surface area as the vegetation base 10, the area to which suspended substances in water adhere increases, and the attached suspension aggregates to a size that facilitates sedimentation, thus promoting sedimentation. can do. Specifically, the vegetation base 10 has a mat surface made of polyester or vinyl chloride fibers having a specific surface area of 1,000 to 2,000 m ² / m ³ , a continuous porosity of 80% or more, and high weather resistance. Use things.

  In addition, as shown in FIG. 4, planting of the extraction plant 40 on the vegetation base 10 is performed by filling a pot 11 made of woven fabric or non-woven fabric with soil 12 made of commercially available horticultural soil or the like. This is done by planting a seedling 40a of a water-drawing plant and installing it on the vegetation base 10 vertically and horizontally as shown in FIG. This is because planting using the pot 11 significantly improves the survival rate of the vegetation base 10. As shown in FIGS. 2 and 3, the planted water extraction plant 40 can have the rhizome 41 extending from the vegetation 11 to the vegetation base 10 and further from the vegetation base 10 to the water.

Here, when the continuous porosity of the vegetation base 10 is less than 80% or the pore size is too fine, the sedimented sludge accumulates in the vegetation base 10 and causes clogging. By setting the ratio to 80% or more, accumulation of sludge in the vegetation base 10 can be prevented, and the contact efficiency with the water W can be maintained. Moreover, considering the fiber strength that can secure a continuous porosity of 80% or more and the strength of the vegetation base 10 can withstand the lodging of the extraction plant 40, the amount of resin of the vegetation base 10 needs to be 16 kg / m ³ or more. . In this case, the specific surface area is 1,000 m ² / m ³ . In other words, when the specific surface area is less than 1,000 m ² / m ³ , the vegetation base 10 is too soft and the grown extracted plant 40 may fall down due to wind load. On the other hand, if the specific surface area exceeds 2,000 m ² / m ³ , the continuous void size of the vegetation base 10 becomes too fine, and the suspended matter is easily clogged. Therefore, a vegetation base 10 having a specific surface area of 1,000 to 2,000 m ² / m ³ and a continuous porosity of 80% or more is used.

  The float 20 (water float 21 and water float 22) is formed of, for example, a pipe made of vinyl chloride or a pipe made of fiber reinforced plastic, and has a sufficiently high buoyancy because it is hollow. ing. Among these, as shown in FIG. 1, a pair of water floats 21 having a length substantially equal to the length of the vegetation base 10 having a square shape or a rectangular shape is disposed along two opposite sides. The underwater floats 22 extend so as to be substantially orthogonal to the overwater float 21, and as shown in FIG. 2 and FIG.

  The fixing member 30 is a hot-dip galvanized steel outer peripheral frame 31 that supports the outer peripheral portion of the vegetation base 10 and a flat surface stretched on the lower surface of the outer peripheral frame 31, and is made of synthetic resin such as polyethylene or rust-proof steel A net 32 made of steel or stainless steel and having a mesh size of 25 to 100 mm, and a required number of beam-like frames 33 made of hot-dip galvanized steel installed on the lower surface of the outer peripheral frame 31 so as not to bend downward. And a water float mounting member 34 made of hot dip galvanized steel for attaching the water float 21 to the outer peripheral frame 31, and an underwater float attachment member 35 made of hot dip galvanized steel for attaching the underwater float 22 to the lower side of the beam frame 33. . Then, by supporting the vegetation base 10 with the fixing member 30 having such a structure, the vegetation base 10 is installed in a state of being submerged in water, and the water W including suspensions such as phytoplankton is efficiently supplied to the vegetation base 10. Can be touched.

  Further, since the water W in the water area to be purified can freely circulate on the vegetation base 10 from the side where the water float 21 is not disposed, suspended substances such as underwater phytoplankton can be present on the surface of the vegetation base 10. And the action of adhering to and sinking to the brewed extraction plant 40 is promoted.

  Preferably, the upper surface of the vegetation base 10 has a water depth of 5 to 15 cm. This is because when the water depth d exceeds 15 cm, the growth of the extraction plant 40 tends to be adversely affected. When the water depth d is less than 5 cm, the water W hardly flows on the upper surface of the vegetation base 10, and suspended substances such as phytoplankton in the water are present. This is because there is a possibility that the action of sinking to the vegetation base 10 and adhering / sinking to the extraction plant 40 may not be obtained, or the water temperature on the vegetation base 10 may rise in summer and adversely affect the growth of the extraction plant 40.

According to the artificial floating island 1 of the first form having the above-described configuration, by abnormal growth of phytoplankton such as Microcystis of the blue-green algae in closed waters such as natural lakes, ponds, city parks, The water quality can be efficiently purified in the situation where the water quality is polluted. This is because the allelopathic substance released into the water from the rhizome 41 of the water extraction plant 40 selected from shiroma, kuyoyoshi, macomo, and cassage planted on the vegetation base 10 suppresses the growth of phytoplankton such as the Microcystis, This is because the suspended matter such as phytoplankton settles on the vegetation base 10 and adheres to and settles on the extracted plant 40, thereby suppressing the occurrence of blue sea bream. In addition, zooplankton such as daphnia and rotifers and bacteria inhabit the surface and voids of the vegetation base 10 composed of a three-dimensional network structure having a large specific surface area, and these micro-animals prey on and decompose phytoplankton. This is because the function is improved.

  Therefore, even in the artificial floating island 1 having an area of 5% to 10% of the water area of the closed water area to be purified, the transparency can be improved, organic pollution can be prevented, and the nutrient salt concentration can be reduced.

  Next, FIG.5 and FIG.6 shows the 2nd form of the artificial floating island which concerns on this invention. The artificial floating island 1 according to the second embodiment also includes a vegetation base 10, a float 20 that floats the vegetation base 10 on the water W, and a fixing member 30 that connects the float 20 to the vegetation base 10. That is, the vegetation base 10 is supported by the float 20 through the fixing member 30 in a state of floating in the water W at an appropriate water depth, and the vegetation base 10 releases an allelopathic substance that suppresses the growth of phytoplankton. The extraction plant 40 is planted.

  The float 20 is composed of a water float 23 and a water float 24 extending in a frame shape along the outer peripheral edge of the vegetation base 10, and is coupled to each other by a band 25 at an appropriate interval in the vertical direction.

  As shown in FIG. 6, a car 36 formed of a hard net is attached to the underwater float 24 as a fixing member 30, and the vegetation base 10 is installed in the car 36. In other words, the vegetation base 10 is supported by the buoyancy of the float 20 through the cage 36, so that the vegetation base 10 is installed in a state where it is submerged in water, and the water W containing suspended matter such as phytoplankton is efficiently supplied. It can come into contact with the vegetation base 10.

  In this case, as shown in FIG. 6, the underwater float 24 is submerged, and the water W in the water area to be purified freely circulates on the vegetation base 10 from the gap δ between the underwater float 23. In this case as well, the upper surface of the vegetation base 10 is set to 5 to 15 cm below the water surface. For this reason, suspended substance such as phytoplankton in water settles on the surface of the vegetation base 10, and the action of adhering to and depositing on the brewed extracted plant 40 is promoted.

  In addition, the vegetation base 10 is the same as that of the 1st form demonstrated previously, The planting method of the extraction plant 40, etc. can be performed similarly to a 1st form. Therefore, the same operation and effect as the first embodiment can be realized.

  Next, FIGS. 7 to 9 show a third embodiment of the artificial floating island according to the present invention. The third embodiment is different from the first embodiment described above in that the floating float 21 in the float 20 is arranged in the vicinity of the four corners of the vegetation base 10 having a square or rectangular planar shape. The configuration of the other parts is basically substantially the same as that of the first embodiment, and the same operations and effects as those of the first embodiment can be realized.

  Next, FIG. 10 shows a fourth embodiment of the artificial floating island according to the present invention. In each of the above-mentioned forms, the float 20 is composed of the water float 21 (23) and the underwater float 22 (24), whereas in the fourth form, the float 20 is composed of only the underwater float 22, and the bottom of the water (pond or An appropriate depth of water d (destination) is obtained through a anchor 50 comprising an anchor 51 driven into the bottom of the swamp G and a anchoring rope 52 having a lower end connected to the anchor 51 and an upper end connected to the fixing member 30. As described in (5), it is anchored in a state of floating in the water W at 5 to 15 cm). Other parts can be configured basically in the same manner as the first embodiment.

  FIG. 11 shows a fifth embodiment of the artificial floating island according to the present invention. In this embodiment, instead of the anchor 50 in the fourth embodiment, the anchor pile 60 driven into the bottom G is anchored in a state floating in the water W at an appropriate water depth d via the vegetation base 10. . Other parts can be configured basically in the same manner as the first embodiment.

  And according to these 4th or 5th form, since the floating height from the bottom G is kept constant by the anchor 50 or the anchor pile 60, in the pond marsh where the water level is constant, the upper surface of the vegetation base 10 It can be suitably employed as means for keeping the water depth d constant.

  Various verification tests for confirming the effect of the artificial floating island of the present invention were conducted, and will be described below.

Demonstration test 1:
Laboratory tests were conducted to confirm the allelopathic effect of the extracted plants. In this test, six kinds of water extraction plants were used : kishobu, ekisho, kusayoshi , makomo, matsukasusuki and himegama.

  As shown in FIG. 12, the test method is as follows. Water 103 is placed in a bucket 101, a vegetation base 102 is set on the bucket 101, and after the water-drawn plant 104 is cultivated by pot planting, the bucket 101 and the vegetation base 102 are After washing, the medium (water 103) in the bucket 101 was replaced and cultivated in a greenhouse for one week. One week later, using water obtained by filtering the water 103 with a 0.25 μm filter paper, the specific growth rate of Microcystis, a blue-forming blue-green algae, was confirmed by bioassay method. did.

As a result of this test, as shown in FIG. 13, the specific growth rate of the blue-green algae is compared with a control plant that has been confirmed not to have an allelopathic effect in water cultivated by Matsukasusuki, Kshobu, and Sekisho. However, it was confirmed that the specific growth rate was significantly decreased in water grown with chickpea, kusayoshi and makomo .

Demonstration test 2:
A field test was conducted to confirm the allelopathic effect of the extracted plants. The test methods are: near the rhizomes of the artificial floating island extraction plants installed in the isolated water area (1,000 m ² , average water depth: about 1.2 m) installed in Yamano Kanuma, Hasuda City, in the isolated water area without artificial floating islands, and Water was collected from a pond swamp outside the isolated water area, and the growth inhibition effect by allelopathy was confirmed by investigating the specific growth rate of Microcystis, a blue-forming blue-green algae, using the bioassay method as in Example 1. As the artificial island, which was planted Typha domingensis, that planted wild rice, using three types of artificial floating island although planted Kasasuge.

As a result of this test, as shown in FIG. 14, the allelopathic effect was confirmed in any of the artificial floating islands planted with three kinds of extraction plants, and no effect was seen in the water area without artificial floating islands or outside the isolated water. . Of these three kinds of water-drawing plants, the result was that maggots had the greatest allelopathic effect.

Demonstration test 3
In order to investigate the thickness of the vegetation base suitable for the development of rhizomes, a square (30 mx 30 cm) with a thickness of 10 cm, 15 centimeters and 20 centimeters in a pool (2 mx 3 m, water depth of about 50 cm) installed outdoors A pot of extracted water plants was planted on the vegetation base of, and a cultivation test was conducted. There were two types of water extraction plants: Himegama and Makomo .

Test results, rhizome of emergent plants, seen as emanating from the sides of the vegetation based on the type, Typha domingensis in depth from vegetation base surface 10 to 15 cm, wild rice is rhizome grows at a depth of 5~16cm I understood it. That is, it was found from the test results that the rhizomes of the extracted water plants in which the rhizomes develop are distributed at a depth of 5 cm to 16 cm. Therefore, it was confirmed that the thickness of the vegetation base is preferably about 7.5 cm (more than the size of the plant pot seedling) to 20 cm (the depth at which the basement stem develops) depending on the type of plant.

Demonstration test 4:
When planting the seedlings of the extraction plant, an outdoor cultivation test was conducted to grasp the effect of the presence or absence of soil on the growth of the extraction plant. The test method consists of an outdoor pool (2m x 3m, depth of water: about 50cm), a pot seedling planted with a seedling of a water extraction plant in a palm fiber pot filled with soil, and a seedling plant without a pot and soil. Each was placed on a vegetation base material and the growth of seedlings was measured. There were two types of water extraction plants: Makomo and Kishobu .

  As a result of the test, when the dry weight (average value of each of the two strains) of the plant body after two years passed after planting was measured, the seedling planted by filling the palm pot with soil and planting as shown in FIG. Compared to the case without soil, the growth of both the above-ground part and the rhizome was significantly different, and it was confirmed that the soil pot was effective for the seedlings.

Demonstration test 5:
In addition, when planting the seedlings of the extraction plant on the floating vegetation island in the actual pond marsh, a field survey was conducted to confirm whether the presence or absence of soil was effective for the growth of the extraction plant. In this test, we investigated the survival rate of water-drawn plants on artificial floating islands installed in the isolated water field (1,000 m ² , average water depth: about 1.2 m) installed in Yamano Kanuma, Hasuda City. As the artificial island, which was planted Typha domingensis, that planted wild rice, using three types of artificial floating island although planted Kasasuge.

As a result of the test, as shown in FIG. 16, all three kinds of extracted plants are planted in a soil pot, and the survival rate is better, and those that do not use soil are extremely worse in the survival rate of plants other than Makomo. I understood.

Demonstration test 6:
Five isolated water areas (15m ² ) closed with a water shielding sheet are installed in Yamanokami Marsh, Hasuda City, where edible mud is deposited and microalgae (dominant species Chroococcus sp.) Grow abnormally. the isolation waters, as shown in Table 1, different artificial floating island (1.5 m ^2/1 group) established the (artificial the floating island specific surface area 1,556m ² / m ^3, 98% continuous porosity of the structure, the thickness of the The vegetation base made of polyester of 7.5 cm and 15 cm was used), and the new deposits under each artificial floating island were investigated. The survey of new deposits was conducted twice a week for about two months, and was measured from the difference between the water quality in the sediment trap and the water quality in the isolated water field collected at the time of the survey.

Since the new sediment velocity is strongly influenced by water quality, the ratio of the water quality to the sediment velocity is expressed as the sediment velocity index SVI (water quality (g · m ⁻³ ) / sediment velocity (g · m ⁻² · d ^-1 ): The number of days required to deposit a unit amount of water (d · m ^-1 )) was evaluated for the sedimentation promoting effect of suspended solids due to the difference in floating island structure. As a result, the relationship between the SVI of SS (suspended material) and Chl-a (chlorophyll-a) and the concentration in the isolated water boundary is shown in FIG. 17 and FIG. , SS and Chl-a were reduced in SVI in the 2nd to 5th districts compared to the case without artificial floating island (1st district), and the sedimentation promoting effect was seen. In particular, the SVI reduction effect of the suspended contact material (5 wards) was high. In the 2nd to 4th districts where the artificial floating island uses a vegetation base made of porous resin mat, the SVI reduction effect of the 4th ward with the vegetation base installed on the water surface was high for SS, but Chl-a was submerged 2 The SVI reduction effect was high in the 3rd and 3rd wards. In addition, the 3 wards with a vegetation base thickness of 15 cm had slightly higher SVI reduction effects than the 2 wards of 7.5 cm, but no significant difference was observed.

In other words, when artificial floating islands with a vegetation base thickness of 7.5 cm or 15 cm were installed, the rate of newly formed sediments increased compared to the isolated water area without artificial floating islands (1 ward), but the vegetation base thickness Despite being twice as large, there was no significant difference in the nascent sediment rate. Therefore, the density (specific surface area) of the vegetation base and the thickness of the vegetation base are such that even if the base density per unit area is too high, suspended matter accumulates in the base and contact precipitation is less likely to occur. It was confirmed that the effect was reduced even if the hit base density was too low. From this, it is considered that 1,000-2,000 m ² / m ³ is appropriate for the specific surface area of the vegetation base, and it is not necessary to consider when the thickness of the vegetation base exceeds 7.5 cm.

Demonstration test 7:
In addition, we examined the predation and decomposition effects of phytoplankton due to the increase of zooplankton. As the method, the following isolated water areas (1,000 m ² ) are set up in Yamano Kanuma in Hasuda City, and the thickness of the vegetation base and planting conditions are set for 2 wards to 4 wards. The polyester porous mat (specific surface area 1,556m ² / m ³ , continuous porosity 98%, 45cm x 50cm) is installed so that the water depth on the surface of the vegetation base is about 5cm and collected in the summer after about one year Then, the zooplankton in the vegetation base was washed out, and the total amount of zooplankton collected by the plankton net of 0.1 mm was quantitatively analyzed to investigate the difference in the existing amount of zooplankton depending on the thickness of the vegetation base and the presence or absence of plants. .
1 ward: No floating island 2 ward: Vegetation base 75 mm thick 3 ward: Vegetation base 150 mm thick 4 ward: Vegetation base 75 mm thick, Makiko 4 plants

As a result of the investigation, as shown in FIG. 19, zooplankton both in the type and the number of individuals increased significantly in the vegetation base of the artificial floating island compared to the water area (1st ward) where there was no artificial floating island. In addition, when the thickness of the vegetation base is 75mm (2nd ward) and 150mm (3rd ward), there is no big difference in the total population density. There was a tendency to increase the number. Those planted with macomo may have reduced the volume of the seedling pot and the vegetation base, but there was a tendency to decrease compared to the case of the vegetation base alone even considering that amount. .

  In order to confirm the effect of the artificial floating island of the present invention, a demonstration test using a small isolated water field was carried out in Yamano Kanuma, Hasuda City, Saitama Prefecture, which is a eutrophic pond swamp predominated by the blue-green algae Microcystis. Here, the knowledge acquired about the presence or absence of an extraction plant, a planting seed | species, and the shielding rate of the artificial floating island (ratio of the area of the artificial floating island with respect to a water area) and the growth inhibitory effect of a phytoplankton is shown.

Nine isolated water boundaries (3.87m x 3.87m = 15m ² , approximately 1m water depth) are placed in Yamanojinuma, and no artificial floating islands are installed in each isolated water boundary as shown in Table 2. In addition to the ward, from August 9th to November 3rd, 2008, a test ward with artificial floating islands with different shielding rates and planting species was established. Among the planting species, as described in the verification test 1 described above, Makomo and Higama are plants having an allelopathic effect, and citrus is a plant having no allelopathic effect.

In addition, the vegetation base of the artificial floating island was installed so that the surface water depth might be 5-10 cm. The vegetation-based porous material is a polyester three-dimensional network structure with a specific surface area of 1,556 m ² / m ³ and a continuous porosity of 98%. In order to cause poor growth when the soil pot was planted in a soil pot, only seedlings were planted directly on the vegetation base.

  In each test zone, water flowed in and out of isolated water due to fluctuations in the water level of Yamanokami Marsh. The water exchange rate in the isolated water area due to the fluctuation of the water level from September 5 to November 3 when the water level was stabilized after the isolated water field was submerged due to heavy rain was 1.5% on average per day.

  FIG. 20 shows the change over time in the Chl-a concentration after the start of the verification test. As can be seen from Fig. 20, the 2nd and 3rd ward where the artificial floating islands that are not planted were installed showed a decreasing tendency compared to the one without the floating island (1st ward). The Chl-a concentration was reduced from the vegetation base with a shielding rate of 5%. In addition, when comparing the test plots with the same shielding rate, the test plots planted with Makomo and Himegama, which have the allelopathic effect, have lower Chl-a concentrations than the second and third plots where artificial floating islands are not planted. In addition, the results showed that the growth of phytoplankton could be suppressed even on an artificial floating island with a vegetation base with a shielding rate of 5%. On the other hand, the 8th and 9th districts where the artificial floating islands planted with buffets without allelopathic effects were installed had a shielding rate of 5% (8th district) compared to the 2nd and 3rd districts where the artificial floating islands were not planted. There was no significant difference, and an increasing trend was seen at a shielding rate of 10% (9 districts).

  Therefore, as a result of this verification test, if artificial floating islands planted with the water-blowing makomo and chickpea that have the allelopathic effect are used, the vegetation substrate adhesion and contact sedimentation effects confirmed in verification test 6 and Due to the combined effects of phytoplankton predation and decomposition due to the increase in zooplankton confirmed in Test 7, the area of the artificial floating island (shielding rate) is 5% of the water area, in other words, 1 of the conventional artificial floating island It was confirmed that the growth of phytoplankton can be suppressed even in an area of about / 6 to 1/3.

DESCRIPTION OF SYMBOLS 1 Artificial floating island 10 Vegetation base 20 Float 21,23 Water float 22,24 Underwater float 30 Fixing member 40 Extraction plant 41 Rhizome 50 Tether 60 Tethered pile

Claims (8)

  An artificial floating island composed of a vegetation base and supporting means for supporting the vegetation base in a state of floating in water, wherein a water-extracted plant that releases an allelopathic substance that suppresses the growth of phytoplankton is planted on the vegetation base An artificial floating island characterized by that.   2. The artificial floating island according to claim 1, wherein the supporting means comprises a required number of floats.   The artificial floating island according to claim 1, wherein the support means is a tether or tether that anchors the vegetation base and the bottom of the water. The artificial floating island according to claim 1, wherein the vegetation base is made of a porous material having a three-dimensional network structure, a specific surface area of 1,000 to 2,000 m ² / m ³ , and a continuous porosity of 80% or more.   The artificial floating island according to claim 1, wherein the vegetation base is formed to a thickness of 7.5 to 20 cm.   The artificial floating island according to claim 1, wherein the vegetation base is submerged so that the surface has a water depth of 5 cm to 15 cm, and water can flow through the vegetation base.   2. The artificial floating island according to claim 1, wherein the vegetation base is supported by a support having a structure in which a net is stretched on a frame fixed to the support means.   The planting of the extracted plant on the vegetation base is made by installing a pot seedling having a structure in which a seedling is planted in soil filled in a pot made of woven or non-woven fabric on the vegetation base. The artificial floating island according to claim 1.

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