JPH088824B2 - Red tide control method - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] With the modernization of fisheries, aquaculture fisheries such as cultivated fisheries and marine farms have become popular for both seawater and freshwater.

The location chosen for aquaculture will be the inland sea because of its safety and convenience. The flow there is slow, and a large amount of organic matter is administered as food. As a result, eutrophication due to excess phosphorus, nitrogen, etc. will lead to abnormal occurrence of various plankton. The most harmful of these is red tide plankton, which is highly toxic and causes great damage to farmed fish. The main genera of this red tide plankton are cyanobacteria, lafittes, and hyperflagellates.

The present invention relates to a method for controlling this harmful red tide plankton.

[Prior Art] Various methods considered for controlling red tide, for example, a method by spraying clay such as montmorillonite (JP-A-53-72362), a method of applying an acid to acid clay and spraying (JP-A-59-21607), In addition, spraying of chemicals such as sodium percarbonate, precipitation with an organic coagulant, etc. However, the safe and reliable red tide control method has not yet been established.

[Problems to be Solved by the Invention] The present invention is a control method generated by studying and elucidating the ecosystem of red tide plankton.

When red tide plankton proliferates rapidly, it is called swimming type immediately after the morphological development. Then, after a few hours, it becomes bow-shaped and stops exercising. It is called the stop type. Next, it becomes a round shape, and finally it becomes a burst type, which reduces the number.

In the previous application, as a result of studying the action of a silicate containing a silicic acid colloid on red tide plankton, it was found that it was excellent in the effect of selectively adsorbing and precipitating stop type red tide plankton.

On the other hand, hydrogen peroxide has long been known to kill red salt plankton. But the mechanism is still unknown. As a result of diligent research on the effect of the hydrogen peroxide on red tide plankton in the present invention, it was confirmed that an effect of accelerating the ecological change of red tide plankton is achieved by adding a large amount of the hydrogen peroxide, but by adding a small amount thereof. That is, when a small amount of hydrogen peroxide is added to swimming type red tide plankton, it immediately changes to the stop type.

[Means for Solving the Problems] The present invention is completed by a synergistic effect of two effects, that is, an effect of promoting an ecological change by a trace amount of hydrogen peroxide and an effect of selectively adsorbing and precipitating silicic acid containing a silicic acid colloid and a silicate. It was done. And the summary is Akashio plankton,
A method for controlling red tide is characterized by dispersing a silicic acid colloid or a silicate colloid and a hydrogen peroxide.

The hydrogen peroxide that can be used here is typified by hydrogen peroxide, and includes peroxide peroxide, urea peroxide and the like. If they are used in large amounts, they are effective in killing the red tide, but they also adversely affect farmed fish. Therefore, it was confirmed that the use of 1 to 50 ppm of hydrogen peroxide preferably did not affect the fish, and that the red tide plankton also shifted from the immediate swimming type to the stopping type.

The silicic acid colloids and silicate colloids applicable to the present invention are polymers of silicic acid monomers derived from soluble silicate solutions.

This polymer is a silicic acid colloid aggregate formed by dimer or more by siloxane bond by condensation dehydration reaction between silanol groups of monomeric silicic acid, and its size does not exceed 1 μm. It is generally called colloidal silicic acid. Therefore, a commercially available colloidal silicic acid solution (SiO ₂ concentration: 10 to 50%, particle size: 0.5 nm to 500 n
m), for example, the product name "Ludox" (made by DuPont),
"Snowtex" (manufactured by Nissan Chemical), "Cataloid"
(Catalyst Kasei) or the like may be used.

Further, not only these commercially available products but also the colloidal silicon dioxide obtained in the process of polymerizing the silicic acid monomer has the effect of the present invention.

For example, it contains a colloidal silicic acid polymer whose pH is adjusted from about 2 to about 10 with a hydrolysis product of an acid of an aqueous solution of alkaline silicate such as sodium silicate or potassium silicate, lithium silicate, ammonium silicate, etc. A salt coexisting substance of an aqueous solution may be used.

Further, a metal such as sodium, aluminum or iron may be added for stabilization in the process of forming the silicic acid colloid which becomes the polymer.

In the dispersion method, the effect can be recognized by spraying the hydrogen peroxide to the red tide plankton solution first and immediately dispersing the silicic acid colloid solution. Even if added, the same effect can be obtained.

[Operation] According to the present invention, the silicic acid colloid or the silicate colloid and the hydrogen peroxide are, as already exemplified variously,
It is a form that can be dispersed at least in red tide plankton, and disperses quickly after being put into water. Then, due to the action of the hydrogen peroxide, the red tide plankton shifts from the swimming type to the stop type, and the red tide plankton that has shifted to the stop type is adsorbed to the silicic acid colloid or the silicate colloid, and the silicic acid colloid or the silicate colloid. And red tide plankton aggregate and precipitate.

At this time, the silicic acid colloids or silicate colloids dispersed in the water settle out only because they are adsorbed and aggregated on the red tide plankton. Effectively participates in the adsorption, and a significant effect depending on the sprayed amount can be obtained. In addition, for example, even under conditions where red tide plankton move along the ocean current, the dispersed silicate colloid or silicate colloid and hydrogen peroxide are
Since the red tide plankton moves along with the ocean current, there is no need to change the spraying position and spray repeatedly.

Further, the amount of hydrogen peroxide is sufficient to change the red tide plankton to a stop type, and the amount of hydrogen peroxide used can be reduced as compared with the case where the red tide plankton is killed by only the hydrogen peroxide. Therefore, in addition to being advantageous in terms of cost, adverse effects on cultured fish and the like are suppressed.

[Effect] As described above, the present invention is a safe substance, is simple, and can effectively precipitate harmful red tide plankton in a short time.

[Examples] Example 1. Silanetona marina culture liquid, a kind of red tide plankton, and silicic acid colloidal liquid (SiO ₂ 4%, NaSO ₄ 1.4%)-1000.
ppm and H ₂ O ₂ -15 ppm were added simultaneously and the plankton number was analyzed.

Example 2. A type of red tide plankton, Sheathnera marina culture solution, silicic acid colloidal solution (SiO ₂ 2%)-1000 ppm, H ₂ O ₂ -5 ppm
Was mixed and added, and the number of plankton was analyzed.

Comparative Example 1 When the red tide plankton culture solution used in Example 1 was analyzed without adding anything, the results were as follows.

Claims (1)

[Claims] 1. A method for controlling red tide, which comprises dispersing a silicic acid colloid or a silicate colloid and a hydrogen peroxide in red tide plankton.