CN107265646A - Method for controlling bloom outbreak of blue algae in urban landscape water body - Google Patents

Abstract

The present invention relates to a method for controlling the outbreak of blue algae blooms in urban landscape water bodies. For urban landscape water bodies after the revetments and lake bottoms are hardened, a hardened planting pool is constructed on the shore to plant emergent plants; for submerged plants, the plants are planted in flower pots and sunk to the bottom of the water body; for floating leaf plants, they are also planted in flower pots and placed at the bottom of the water body. By planting aquatic plants and ensuring the planting area and biomass of aquatic plants, the excessive growth and reproduction of algae in the water are suppressed, and the blue algae blooms are suppressed and eliminated. While effectively controlling the outbreak of blue algae blooms, the present invention can also maintain the clear water state of the water body, improve the landscape effect of the water body, provide a good living space and habitat for benthic organisms, form a high-density zooplankton community, and improve biodiversity. The potted aquatic plants of the present invention are easy to replace and manage, and have the advantages of simple operation and maintenance, low investment, and low energy consumption.

Description

A method for controlling the outbreak of cyanobacteria blooms in urban landscape water bodies

technical field

The invention relates to the technical field of ecological engineering, in particular to a method for controlling the outbreak of cyanobacteria blooms in water bodies of urban landscapes by using aquatic plant blending.

Background technique

Due to the problem of eutrophication, urban landscape water bodies are often polluted by cyanobacteria blooms, resulting in a drop in dissolved oxygen in the water body, death of fish and shrimp, and stench in the water, seriously affecting the water ecological function and landscape effect of the water body. The fundamental solution to cyanobacterial blooms is to improve the water quality and water ecological environment system of landscape water bodies. With the strengthening of environmental pollution control, the water quality of water bodies has been improved, and many urban landscape water bodies can meet the water quality requirements of Class IV–V in the "Environmental Quality Standards for Surface Water" (GB3838-2002), but the problem of cyanobacteria overgrowth has not been resolved. , Algal blooms still break out frequently. For such landscape water bodies, there is limited room for water quality improvement, and it is difficult to eliminate the path of algal blooms by improving water quality.

The biological method is mainly from an ecological point of view, using the nutrient competition and predator relationship between organisms to control the growth of algae, by establishing a stable water ecosystem, maintaining the balance of the community structure, and promoting the interaction between aquatic organisms, nitrogen and phosphorus nutrients Transformed into animals and plants, and through the allelopathy of aquatic plants and microorganisms, the reduction of phytoplankton biomass and the improvement of the water ecological environment are realized. At present, biological methods to control cyanobacteria mainly include methods such as microbial algae removal, aquatic organism manipulation and aquatic plant inhibition. The aquatic plant method is to plant aquatic plants in water, take advantage of the advantages of aquatic plants and algae to compete for light and nutrients, and allelopathy to inhibit the growth of algae. This method can achieve the purpose of long-term, stable and effective control of algal blooms. Aquatic plants are an important part of the lake ecosystem and have an important impact on maintaining the structural capacity and stability of the lake ecosystem. The restoration technology of eutrophic water body with aquatic plants as the core is one of the current research hotspots in the field of environment. The common method of aquatic plant restoration is to plant aquatic plants directly in the water body, and the roots of the plants take root in the sediment. However, the particularity of the urban landscape water body makes it difficult for directly planted aquatic plants to survive.

Because urban landscape water bodies are different from general natural large-scale lake water bodies, most of them are shallow water bodies with small water depth, strong static performance, poor fluidity, small water environment capacity, low self-purification ability, and extremely fragile ecosystems, which are prone to accumulation of nutrients . On the other hand, urban landscape water bodies, especially in most water-deficient areas in the north, are facing the plight of water shortage. In order to prevent water leakage in landscape water bodies and reduce ecological water consumption, the pool walls and lake bottoms of many landscape water bodies are used as Hardening and anti-seepage treatment are required, which makes the water ecological environment of the landscape water body significantly different from that of natural lakes. The thickness of the bottom mud is small, which is not enough to provide soil for the growth of aquatic plants, and aquatic plants cannot be directly planted and grown like natural lakes.

Therefore, the present invention proposes a control method for cyanobacterial blooms for hardened urban landscape water bodies, including the planting methods and types of aquatic plants (submerged, emergent and floating leaf plants), and through aquatic plant science Reasonable planting, use its water purification function to control the excessive reproduction of cyanobacteria in landscape water. Adopting the method of the present invention can stably, continuously and effectively control algae blooms and increase the landscape effect of water bodies. The method is simple to operate, and the growth of plants is easy to manage. The method can obviously save manpower in the control of cyanobacteria blooms, the control cost is low, and it has obvious advantages. ecological, economic and landscape benefits.

Contents of the invention

Therefore, the object of the present invention is to provide a kind of method utilizing aquatic plants to control cyanobacteria bloom, to suppress the growth of cyanobacteria in urban landscape water body, eliminate the outbreak of cyanobacteria bloom, protect landscape water body ecosystem, bring into play the ecology of landscape water body landscape effect.

The technical problem to be solved by the present invention lies in the method of planting aquatic plants. This method is easy to operate and is suitable for hardened landscape water bodies at the shore and the bottom of the lake. It has obvious effects on the control of algae blooms and the improvement of water quality, and can be easily Well combine the biological advantages of nature to maximize ecological benefits and maintain ecological balance. In order to solve the above-mentioned technical problems, the cyanobacteria bloom control method provided by the invention comprises the following steps:

(1) Construct planting ponds for emergent plants: build planting ponds around the water body, lay humus-containing culture soil in the ponds, and the area of the planting ponds accounts for 10–30% of the water body area;

(2) Planting of emergent plants: select emergent plants that have the control effect of cyanobacteria bloom and also have landscape ornamental value, and plant them in the planting pool of step (1);

(3) Planting of submerged plants: select submerged plants that have the effect of controlling cyanobacteria blooms, plant them in flower pots, and then sink the flower pots into the bottom of the water to place them. The grown submerged plants cover 50% of the bottom area of the water body. –85%;

(4) Planting of floating-leaf plants: Select floating-leaf plants and plant them in flowerpots and place them on the bottom of the lake. The grown floating-leaf plants cover 10–20% of the water body.

Further, the planting pool described in step (1) is a pool body made of brick-concrete cement, the wall of the pool body is vertical to the bottom of the water body, and forms a closed internal space with the shoreline and the bottom of the lake; the planting pool is long and narrow and irregularly shaped, and the pool The body width is 0.5–5.0 m, the depth is 0.3–2.0 m, and the total length accounts for 30–70% of the shoreline length of the landscape water body. The planting pool is 20–50 cm below the water surface, and the lake water enters the planting pool through the upper part of the pool body.

Most emergent higher plants are distributed in 100-150cm of water. Most of the artificially constructed landscape water bodies are deep in the middle and shallow around. In order to ensure that the landscape of plants on the water surface is dense and dense, and will not affect the viewing of other scenery on the shore of the water body, planting ponds are not suitable. Make the pond full of greening and surround the landscape water body for a week. In order to ensure the realization of the above landscape, multiple planting ponds can be set along the shoreline of the landscape water body.

Further, the emergent plants described in step (2) that have the effect of controlling cyanobacteria blooms and have landscape ornamental value are: 1) reed ( Phragmites australis ), a perennial aquatic or wet tall grass that grows beside irrigation ditches, In river embankment swamps, etc., the plants of reeds are tall, with well-developed creeping rhizomes underground, the stems are upright, 1-3 meters high, easy to manage, adaptable to a wide range of environments, and grow fast. The plant of choice for water purification, marsh wetlands, and landscaping projects; 2) Lotus ( Nelumbo nucifera ), flowering period from June to September, blooming in the morning and closing in the evening every day, fruit ripening period from September to October, because the underground stems of lotus root can absorb water well The product of aerobic microorganisms decomposing pollutants, so lotus can help polluted water bodies restore the food chain structure, and promote the water ecosystem to gradually realize a virtuous cycle; 3) Cattail ( Typha orientalis ), flowering and fruiting period from May to August, likes warm and humid climate and humidity 4) Calamus calamus ( Acorus calamus ), flowering period from June to September, fruit period from August to October, suitable for waterscape shore and water body greening, can also be planted in Shallow water; 5) Arrowhead mushroom ( Sagittaria trifolia ), flowering period from July to September, has strong adaptability, can grow in shallow water areas of various water surfaces on land, but requires sufficient light, mild climate, and relatively leeward environment It needs fertile soil, but it needs to grow on clay that is not too deep; 6) Lythrum salicaria , flowering period from July to August, can be arranged in sheets in shallow water beside lake banks and rivers, and its flowering period is long. The color is bright, and it can be enhanced by planting with lotus; 7) Water onion ( Scirpus validus ), a perennial emergent herbaceous plant, with a plant height of 1–2 meters, a tall and straight stem, a cylindrical, hollow, rhizome Thick and prostrate, with many fibrous roots, it often grows in swamps, ditches, poolsides, and lakeside shallow water in nature. It is mainly used as background material in waterscapes.

Further, in step (2), emergent plants must be selected from three or more types for collocation and planting, and the collocation should be high and low, and the density should be consistent.

Aquatic plants can be divided into three categories according to their tillering characteristics: the first category is not tillering, such as Sagittarius; the second category is only tillering once a year, such as Iridaceae plants; the third category is continuous tillering during the growth period, such as Zailihua, water onion etc. The planting density can be adjusted according to the differences in the tillering characteristics of aquatic plants. Those that do not tiller and those that only tiller once a year but have passed the tillering stage when planted should be densely planted. For those that are constantly tillering during the growth period, it can be slightly sparser. The planting density is 1–30 plants/m ² , for cluster-type emergent plants, preferably 3–5 plants/m ² of lotus, 10–12 plants/m ² of water onion, 1–4 plants/m ² of Zailihua, Cattail 20–25 plants/m ² , Sagittarius 10–16 plants/m ² , Chitula 16–25 plants/m ² , Reed 16–20 plants/m ² .

Further, the submerged plants described in step (3) are: 1) Myriophyllum spicatum Linn., Myriophyllum spicatum Linn. , Myriophyllum spicatum Linn., a perennial stout submerged herb with smooth, cylindrical, The rhizomes are born in the mud, the flowering period is from June to August, and they grow well in slightly alkaline soils. They are good in warm, humid and sunny climates. They are not cold-resistant. After winter, the rhizomes survive the winter in the mud and grow in summer. It is vigorous, grows slowly in winter, and can tolerate low temperature. It can be used as an ornamental plant. It is a pioneer species of water purification in ecological restoration of lakes and other waters. It can not only quickly remove nutrients such as nitrogen and phosphorus in water bodies, but also absorb heavy metal elements; 2) Najas marina ( Najas marina ), Najas family, Najas genus, annual submerged herb. Multi-branched, leaves often clustered at the ends of branches or opposite, leaves banded, with 6-11 spiny teeth on the margin, oval fruit, flowers and fruits in summer and autumn, grow in fresh water, brackish water, salt water or shallow sea water Good, the stem nodes of the plant are very firm and not easy to detach. It grows in lakes and other still water areas, which can increase oxygen in water and purify water quality. It is a commonly used species for ecological restoration of water pollution; 3) Najas minor, Najas minor Algae, annual submerged herb. Cylindrical stem, smooth without teeth, many branches, bifurcated, linear leaves, heart-shaped upper part of the leaf sheath, flowering and fruiting period from June to October, often in small clusters in ponds, lakes, ditches, rice fields, Can be born at the bottom of several meters deep; 4) Chara vulgaris , Characeae, Chara genus, grows rapidly, can quickly absorb a large amount of nitrogen and phosphorus in water, and has strong water purification ability; 5) Black algae ( Hydrilla verticillata ), Hydrocharidaceae, Hydra, monocotyledonous perennial submerged plants. The stems are upright and slender, 50–80cm long, and the leaves are banded-lanceolate, widely distributed in ponds, lakes and ditches; 6) Potamogeton crispus Linn ., Potamogeton crispus Linn . Leaf plants, mostly born in ponds, lakes, and streams, widely distributed in China, can be used as fish feed or green manure, and are also good greening materials in lakes, ponds, and small water features, and have a high ability to enrich zinc; 7) Velumbo nucifera Gaertn ( Velumbo nucifera Gaertn ): Hydrocharidaceae, genus Valeria, is a perennial stemless submerged herb with stolons, long leaves, emerald green, clumps, and grows in ditches, rivers, ponds, and lakes.

Further, the planting method described in step (3) is to select three or more of the above submerged plants, and the collocation combination must include Trichosanthes spicaculata and Nasia chrysalis.

For submerged plants, use random mixed planting methods to plant the flower pots planted with submerged plants into the bottom of the lake. The diameter of the flower pots is between 30-70 cm, the height is between 30-60 cm, and the distance between the pots is 40 cm. Between -80 cm, 30-80 submerged plants can be planted in each flower pot. Use field soil, pond mud or organic clay soil as the subsoil for potting, and then cover the surface with a layer of coarse sand with a diameter of 1 to 2 cm to prevent Irrigation or disturbance causes turbidity; the height of water needed for submerged plants must exceed the height of the plants in order to allow the stems and leaves to stretch naturally; the planting density of submerged plants is: 20–30 plants/m ² of P. spicanus; 10– 15 strains/m ² ; 10–15 strains/m ² of Cassia minor; 20–30 strains/m ² of Charophyllum generalissimus; 20–30 strains/m ² of Hydrilla ^; Grass 20–30 plants/m ² . Since most aquatic plants need sufficient sunlight, especially during the growth period (between April and October every year), if the sunlight is insufficient, there will be leggy growth, small and thin leaves, and no flowering. The suitable planting time is early spring and March every year. to May.

Further, the floating leaf plants in the step (4) are: 1) water lily ( Nymphaea spp. ), the flowering period is from May to September, and the fruiting period is from July to October. The roots of water lily can absorb lead and mercury in the water , phenol and other toxic substances, which are rare plant materials for water purification; 2) Euryale ferox Salisb , flowering period July-August, fruit period August-September, annual large aquatic herb, submerged leaves arrow-shaped or oval kidney Shape, 4-10cm long, no thorns on both sides, no thorns on petioles, leathery floating leaves, oval reniform to round, 10-130 cm in diameter; 3) Wanglian ( Victoria regia Lindl ), flowering in summer, solitary, floating on the water surface It is white at first, and turns deep red the next day and withers. It is a perennial or annual large floating leaf herb with short erect rhizomes and well-developed adventitious roots. It is white with giant and peculiar disk-like leaves. Spectacular.

The leaves of floating-leaf plants float on the water surface, and they are also planted in flower pots, usually at a water depth of 30-100 cm. The suitable planting density of floating-leaf plants is: 1-2 water lilies/m ² , 1 Gorgon seed/4 –6 m ² , 1 king lotus/4–6 m ² ; choose one or two kinds of floating-leaf plants to plant with emergent plants, and plant them in the water outside the planting pool in the lakeshore area.

Further, the landscape water body is an urban landscape water body with an average water depth of 0.6-2.5 m.

The method for controlling cyanobacteria blooms in urban landscape water bodies should carry out daily regular maintenance and management of aquatic plants, including: daily inspection and management of the growth of aquatic plants, including checking for pests and diseases; regular removal of weeds and garbage in the water; inspection Whether the plants are crowded or rare, clear them if they are too crowded, and replant if they are too few; trim the submerged plants that grow out of the water surface to make them lower than the water surface; harvest the emergent plants in winter to ensure their overwintering and next year Germinate and grow.

The advantages of the present invention are:

1) Planting aquatic plants can form a diversified aquatic plant community of submerged-floating leaves-emerging water, which can well absorb nutrients such as nitrogen and phosphorus in the water, reduce the degree of eutrophication of the water body, and maintain the clarity of the landscape water quality. Has a good landscape effect;

2) The present invention also provides a good living space and habitat for benthic organisms, forms a high-density zooplankton community, improves biodiversity, increases predation on floating algae, and can control cyanobacteria blooms in a durable, stable and effective manner outbreak, and maintain the balance and stability of the aquatic ecosystem;

2) Restoring polluted water bodies in a biological and ecological way is beneficial to reduce construction and maintenance costs, and can create a beautiful environment in harmony between man and nature, and bring landscape effects while purifying water quality;

3) Planting aquatic plants has little damage to the environment, low cost, no need to inject chemicals into the water body, and will not cause secondary pollution;

4) Simple operation and maintenance, small investment, low engineering cost and low energy consumption;

5) The planting method of submerged plants in flowerpots can keep the water quality clean, which is conducive to the control of plants and facilitates the replacement of plants.

Description of drawings

In order to illustrate the technical solutions in the prior art more clearly, the prior art will be further described in detail below in conjunction with the accompanying drawings.

Fig. 1 is a schematic diagram of planting aquatic plants in a landscape water body according to the present invention.

Fig. 2 is the variation trend diagram of the transparency (SD) of the water body after the embodiment treatment.

Fig. 3 is the change trend chart of chlorophyll a (Chla) of the water body after the embodiment treatment.

Fig. 4 is the change trend chart of the total nitrogen (TN) of the water body after the embodiment treatment.

Fig. 5 is a graph showing the change trend of total phosphorus (TP) in the water body treated in the embodiment.

Fig. 6 is the change trend chart of the chemical oxygen demand (COD) of the water body after the embodiment treatment.

detailed description

The present invention will be further described below in conjunction with the embodiments, and the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. The scope of protection is not limited thereto.

Introduction to the test background: The test site is a landscape water body in a park. Most of the park is closed or semi-closed slow-flowing water bodies with static or poor fluidity. The water environment capacity is small and the self-purification ability is low. Prone to cyanobacteria blooms. Coupled with the injection of a large amount of recycled water, the degree of eutrophication in the water body has increased. Therefore, consider planting aquatic plants by the technical scheme of the present invention. The small experimental lake has an area of 720 m ² and an average water depth of 0.9 m. Both the lake wall and the bottom of the lake have been hardened. Technical scheme of the present invention comprises the following steps:

(1) Construction of emergent plant planting pools: four planting pools were built along the water body, and humus-containing cultivation soil was laid in the pools. The total plane area of the planting pools was 180 m ² , accounting for 25% of the water surface area; the planting pools were Narrow and irregular shape, the width of the pool body is 0.5–3.0 m, the average width is 2.1 m, and the depth is 0.5 m. The total length accounts for 70% of the shoreline length of the landscape water body. The upper part of the body enters the planting pool;

(2) Planting of emergent plants: select emergent plants that have the effect of controlling cyanobacteria blooms and have landscape ornamental value, and plant them in the planting pond. The selected emergent plants are lotus, calamus and water onion, of which 363 are lotus, Covering an area of 121 m ² , 1175 calamus plants covering an area of 41 m ² , 48 water onions covering an area of 4m ² ;

(3) Planting of submerged plants: select the submerged plants of cyanobacteria bloom control effect, P. spicaculata, Cassia macrophylla and Cassia spp. to be planted in flower pots, then sink the flower pots to the bottom of the water, and place them outside the planting pool. The area is arranged in concentric circles, with a pot diameter of 40 cm and a pot interval of 50 cm; 60 pots of P. spica, 1,800 plants in total, 30 pots of Twisteria spp., 1,000 plants in total, and 30 pots of T. chinensis, 1,200 plants in total; Water plants are mixed and planted, and the covered area of submerged plants after growth accounts for 60% of the bottom area of the water body;

(4) Planting of floating-leaf plants: select floating-leaf plants, plant them in flower pots and place them on the bottom of the lake. The grown floating-leaf plants cover 15% of the water body area.

In order to verify the treatment effect, before and after the ecological modification of aquatic plants, the water quality of the water body was tracked and monitored month by month, and surface water samples were collected (depth less than 0.5 m). The specific data are as follows:

(1) Variation law of transparency: As can be seen from Figure 2, with the change of seasons, the variation range of water body transparency (SD) is 30–117 cm, but the overall water transparency shows a trend of improvement. The low transparency in winter is related to the water depth, and the water body can be crystal clear. The repaired SD can be maintained in a clean water state continuously and stably;

(2) Changes in Chla concentration: Figure 3 shows that the Chla content had a maximum value of 45.3 μg/L from June to September before restoration, and the algae grew vigorously, and then gradually decreased. However, after restoration measures were taken, Chla remained at a low level, with an annual average concentration of 8.7 μg/L, which was lower than the eutrophic Chla standard limit of 10 μg/L, and the growth of algae was inhibited, thereby controlling the algae bloom happened;

(3) Variation law of TN concentration: Figure 4 shows that before ecological restoration, the TN concentration in the water body exceeded the limit value of the Class V surface water quality standard; after planting aquatic plants, the total nitrogen concentration in the water body decreased from 1.98 mg/L to 1.03 mg /L. After five months after ecological restoration, the total nitrogen was significantly lower than the limit value of Class IV surface water quality standards. By November of the same year, the concentration of total nitrogen in the water body had dropped by 48.0% compared with the same period before restoration;

(4) Variation law of TP concentration: Figure 5 shows that after the restoration of aquatic plants, the total phosphorus concentration in the water body also showed a downward trend. , the total phosphorus was reduced by 56.9%, and the annual TP average was lower than the Class IV surface water quality standard;

(5) Change law of COD concentration: Figure 6 shows that through the self-purification effect of aquatic plants, the COD content in the water body is significantly lower than that of Class IV water quality from July to November after restoration, and by November after restoration, the COD content of the water body The COD content dropped to 24.7 mg/L, a decrease of 27.6% compared with that before repair.

After implementing the technology of the present invention, through water quality monitoring and analysis and comparison, it was found that the excessive growth of algae in the water was suppressed, no bloom broke out in summer, the content of nitrogen and phosphorus nutrients in the water was reduced, the transparency was obviously improved, and the effect of crystal clearness was achieved. The invention realizes obvious improvement of water body landscape effect while controlling cyanobacteria bloom.

Claims (7)

1. the method for controlling the outbreak of cyanobacteria bloom in urban landscape water body is characterized in that comprising the following steps: (1) Construct planting ponds for emergent plants: build planting ponds around the water body, lay humus-containing culture soil in the ponds, and the area of the planting ponds accounts for 10–30% of the water body area; (2) Planting of emergent plants: select emergent plants that have the control effect of cyanobacteria blooms and have landscape ornamental value, and plant them in the planting pool of step (1); (3) Planting of submerged plants: select submerged plants that have the effect of controlling cyanobacteria blooms, plant them in flower pots, and then sink the flower pots into the bottom of the water to place them. The grown submerged plants cover 50% of the bottom area of the water body. –85%; (4) Planting of floating-leaf plants: Select floating-leaf plants and plant them in flowerpots and place them on the bottom of the lake. The grown floating-leaf plants cover 10–20% of the water body. 2. The method according to claim 1, wherein the landscape water body has hardened revetments and lake bottoms, and the average water depth is 0.6-2.5 m. 3. The method according to claim 1, wherein the planting pool is a pool body made of brick-concrete cement, and the wall of the pool body is perpendicular to the bottom of the water body, forming a closed interior space with the shoreline and the bottom of the lake; the planting pool is Narrow and irregular shape, the width of the pool body is 0.5-5.0 m, the depth is 0.3-2.0 m, the total length accounts for 30-70% of the shoreline length of the landscape water body, and the planting pool is 20-50 cm below the water surface. 4. The method according to claim 1, characterized in that three or more types are selected from emergent plants Phragmites reed, lotus, calamus, arrowhead mushroom, celery, and water onion for collocation planting. 5. The method according to claim 1, characterized in that, three or more are selected from the submerged water plants P. If there are more than three kinds, they should be planted together, and the collocation combination must include Trichosanthes spicaris and Nasia chrysalis. 6. The method according to claim 1, characterized in that one or two are selected from floating-leaf plants water lily, gorgon , and king lotus for collocation planting. 7. The method according to claim 1 and claim 5, wherein the diameter of the flowerpot for planting submerged plants is between 30-70cm, the height is between 30-60cm, and the distance between the pots is between 40-80cm, Plant 30–80 submerged plants per pot.