Method for Establishing Submerged Vegetation System in Eutrophic Water Body

Abstract

The present disclosure relates to a water environment governance technology, and particularly discloses a method for regulating primary productivity in a eutrophic water body. Emerging plants are cultivated in a water area to be governed to improve anti-wind wave and anti-water flow capabilities of the water area to be governed and establish a relatively stable microenvironment; and a modified clay molecular sieve, phosphorus-accumulating bacteria, grass seeds of submerged plants and silty clay are used to prepare a modified clay molecular sieve ecological base, and the modified clay molecular sieve ecological base is uniformly added to the water body of the area to be governed to inhibit the emission of phosphorus in the deposit and reduce disturbance, so that the cyanobacteria in the deposit is fixed, thereby improving the oxygen-deficient microenvironment of a sediment-water interface and achieving the objective of inhibiting growth of cyanobacteria.

Claims

1. A method for establishing a submerged vegetation system in a eutrophic water body, comprising: cultivating emerging plants in a water area to be governed to improve anti-wind wave and anti-water flow capabilities of the water area to be governed; and using a modified clay molecular sieve, phosphorus-accumulating bacteria, grass seeds and silty clay to prepare a modified clay molecular sieve ecological base, and uniformly adding the modified clay molecular sieve ecological base to the water body of the area to be governed.

2. The method according to claim 1, wherein the grass seeds are grass seeds of submerged plants, and wherein the submerged plants comprise Potamogeton crispus and Vallisneria spiralis.

3. The method according to claim 2, further comprising preparing the modified clay molecular sieve ecological base, comprising: weighing the modified clay molecular sieve and the silty clay in a ratio of 1:1 and adding the grass seeds and the phosphorus-accumulating bacteria, and uniformly mixing a mixture, wherein an addition amount of the grass seeds is 40 to 60 seeds/m.sup.2, and an addition amount of the phosphorus-accumulating bacteria is 50% (v/v) relative to a total volume of the modified clay molecular sieve and the silty clay.

4. The method according to claim 1, wherein a first addition amount of the modified clay molecular sieve ecological base is not less than 500 g/m.sup.2.

5. The method according to claim 4, wherein the modified clay molecular sieve ecological base is supplementally added every 5 to 7 days after the first addition, and a supplemental addition amount is 50% of the first addition amount.

6. The method according to claim 4, wherein a cultivation density of the emerging plants is between 5 and 6 plants/m.sup.2.

7. The method according to claim 6, wherein the emerging plants are respectively selected from one or more of Pontederia cordata, Typha orientalis and Canna indica and one or more of native organisms.

8. The method according to claim 6, wherein the emerging plants needs are cultivated before recovery of the cyanobacteria.

9. The method according to claim 1, wherein a water depth of the water area is less than 3 meters and a wind speed of the water area is less than 8 m/s.

Description

DETAILED DESCRIPTION

[0029] The preferred implementations of the present disclosure will be described in detail below in conjunction with embodiments. It should be understood that the following embodiments are given for illustrative purposes only, and are not intended to limit the scope of the present disclosure. Those skilled in the art can make various modifications and substitutions to the present disclosure without departing from the objective and spirit of the present disclosure.

[0030] Experimental methods used in the following embodiments are conventional methods unless otherwise specified.

[0031] Materials, reagents and the like used in the following embodiments are commercially available unless otherwise specified.

Embodiment 1

[0032] An in-situ enclosure experiment was established in a laboratory. The simulated water depth was 1.0 to 2.0 m, and nutrients such as cod, N, P and the like were added such that a water body reached a eutrophic level. An experimental system was composed of 9 PVC permeable enclosures (5 m×2.5 m), and the bottom edges of enclosure cloths were buried with gabions to prevent the exchange of water bodies inside and outside the enclosures, and were fixed in the water body with steel pipes. Before the start of the experiment, all the enclosure cloths were submerged in water and allowed to stand for two weeks until the water bodies inside and outside the enclosures were fully balanced.

[0033] Three treatment measures were taken in the experiment, and three enclosures were adopted to repeat the experiment for each treatment.

[0034] Group A was a control group (not treated).

[0035] Group B was a modified clay molecular sieve ecological base: weighing a modified clay molecular sieve and silty clay in a ratio of 1:1, adding grass seeds and phosphorus-accumulating bacteria, and uniformly mixing a mixture. The addition amount of the grass seeds was 40 to 60 seeds/m.sup.2, and the grass seeds were Potamogeton crispus seeds and Vallisneria spiralis seeds in a number ratio of 2:1. The addition amount of the phosphorus-accumulating bacteria was 50% (v/v) relative to the total volume of the modified clay molecular sieve and the silty clay.

[0036] A preparation method of the modified clay molecular sieve included: selecting clay including water body sediment and shore, and using the clay after drying, grinding and sieving, or purchasing a professional clay sewage treatment agent; and adding the treated clay to a chitosan solution to form a slurry, or spraying the chitosan solution on the constantly stirred clay (referring to CN 102502969A), where the amount of the chitosan was 1%-1.5% (w/w) of the clay.

[0037] The phosphorus-accumulating bacteria were commercially available products, for example, anaerobic phosphorus-accumulating bacteria that can be purchased from Yangzhou Haicheng Biotechnology Co., Ltd. The product was in the form of bacterial powder, and the content of the phosphorus-accumulating bacteria was up to 95% or above.

[0038] The first addition amount of the modified clay molecular sieve ecological base was not less than 500 g/m.sup.2. The modified clay molecular sieve ecological base was supplementally added every 5 to 7 days after the first addition, and the supplemental addition amount was 50% of the first addition amount.

[0039] In Group C, only the grass seeds were added: the addition amount of the grass seeds was 40 to 60 seeds/m.sup.2 (40 to 60 grass seeds were added per square meter of a water area), and the grass seeds were the Potamogeton crispus seeds and the Vallisneria spiralis seeds in a number ratio of 2:1.

[0040] In the experiment, a draught fan was configured to simulate wind waves, the wind speed was set to 7 m/s, and the water temperature was controlled at 25 degrees, which was suitable for recovery and reproduction of the cyanobacteria, and the seedling density of the Vallisneria spiralis was 600 plants/enclosure. After the system ran for two months, the density of the cyanobacteria and the germination rate of submerged plants in the water were tested.

[0041] A phytoplankton net was configured to take a phytoplankton sample, the density of the cyanobacteria was counted with a microscope, and at the same time, submerged plant seedlings were counted to calculate the germination rate of the seeds.

[0042] The results showed that compared with Group A, the number of the cyanobacteria in Group B was decreased by 80%, the germination rate of submerged plant seeds reached 82.5%, and the germination rate of the seeds was increased by 50%, so the effect was significant; and compared with group C, the number of the cyanobacteria in Group B was decreased by 70%, and the germination rate of the seeds was increased by 30%.

Embodiment 2

[0043] An in-situ enclosure experiment was established in a laboratory. The simulated water depth was 1.0 to 2.0 m, and nutrients such as cod, N, P and the like were added such that a water body reached a eutrophic level. An experimental system was composed of 6 PVC permeable enclosures (5 m×2.5 m), and the bottom edges of enclosure cloths were buried with gabions to prevent the exchange of water bodies inside and outside the enclosures and were fixed in the water body with steel pipes. Before the start of the experiment, all the enclosure cloths were submerged in water and allowed to stand for two weeks until the water bodies inside and outside the enclosures were fully balanced.

[0044] Two treatment measures were taken in the experiment, and three enclosures were adopted to repeat the experiment for each treatment.

[0045] Group A was a modified clay molecular sieve ecological base: the treatment was the same as Group B in Embodiment 1.

[0046] In Group B, no phosphorus-accumulating bacteria were added: compared with the modified clay molecular sieve ecological base in Group A in this embodiment, no phosphorus-accumulating bacteria components were added, and the other treatments were the same.

[0047] In the experiment, a draught fan was configured to simulate wind waves, the wind speed was set to 7 m/s, and the water temperature was controlled at 25 degrees, which was suitable for recovery and reproduction of cyanobacteria, and the seedling density of Vallisneria spiralis was 600 plants/enclosure. After the system ran for 2 months, the density of the cyanobacteria and the germination rate of submerged plants in water were tested.

[0048] A phytoplankton net was configured to take a phytoplankton sample, the density of the cyanobacteria was counted with a microscope, and at the same time, submerged plant seedlings were counted to calculate the germination rate of seeds.

[0049] The results showed that compared with Group B, the number of the cyanobacteria in Group A was decreased by 80% relative to the control, the germination rate of submerged plant seeds reached 82.5%, and the germination rate of the seeds was increased by 27% relative to Group B, so the effect was significant.

Embodiment 3

[0050] An in-situ enclosure experiment was established in a laboratory. The simulated water depth was 1.0 to 2.0 m, and nutrients such as cod, N, P and the like were added such that a water body reached a eutrophic level. An experimental system was composed of 6 PVC permeable enclosures (5 m×2.5 m), and the bottom edges of enclosure cloths were buried with gabions to prevent the exchange of water bodies inside and outside the enclosures and were fixed in the water body with steel pipes. Before the start of the experiment, all the enclosure cloths were submerged in water and allowed to stand for two weeks until the water bodies inside and outside the enclosures were fully balanced.

[0051] Two treatment measures were taken in the experiment, and three enclosures were adopted to repeat the experiment for each treatment.

[0052] Group A was a modified clay molecular sieve ecological base: the treatment was the same as Group B in Embodiment 1.

[0053] In Group B, a formula of the ecological base was changed (to an ordinary molecular sieve): compared with the modified clay molecular sieve ecological base of Group A in this embodiment, the modified clay molecular sieve was replaced with the ordinary molecular sieve, and the other treatments were the same.

[0054] In the experiment, a draught fan was configured to simulate wind waves, the wind speed was set to 7 m/s, and the water temperature was controlled at 25 degrees, which was suitable for recovery and reproduction of cyanobacteria, and the seedling density of Vallisneria spiralis was 600 plants/enclosure. After the system ran for 2 months, the density of the cyanobacteria and the germination rate of submerged plants in water were tested.

[0055] A phytoplankton net was configured to take a phytoplankton sample, the density of the cyanobacteria was counted with a microscope, and at the same time, submerged plant seedlings were counted to calculate the germination rate of seeds.

[0056] The results showed that compared with Group B, the number of the cyanobacteria in Group A was decreased by 80% relative to the control, the germination rate of submerged plant seeds reached 82.5%, and the germination rate of the seeds was increased by 30% relative to Group B, so the effect was significant.

[0057] Although the present disclosure has been described in detail above with general descriptions and specific implementations, some modifications or improvements can be made based on the present disclosure, which is obvious to those skilled in the art. Therefore, all these modifications or improvements made without departing from the spirit of the present disclosure shall belong to the protection scope of the present disclosure.