An ecosystem construction method suitable for small and micro wetlands

Abstract

The present application relates to the technical field of water body ecological restoration, and provides an ecosystem construction method suitable for small and micro wetlands, which comprises the following steps: firstly, topographic modification is performed on the target small and micro wetland; then, aquatic plants and animals are introduced in stages and in proportion according to the niche complementation and food chain inhibition principles, and microorganisms are inoculated for system strengthening; finally, water quality monitoring is performed on the constructed ecosystem, so that the purpose of long-term maintenance of clear water and ecological stability at low cost is achieved.

Description

Technical Field

[0001] This invention relates to the field of aquatic ecological restoration technology, and in particular to a method for constructing an ecosystem suitable for small wetlands. Background Technology

[0002] Small wetlands, as important ecological landscapes and stormwater management facilities, are widely used in urban and rural construction. However, the construction and management of existing small wetlands often face the following technical bottlenecks: 1. Fragile ecosystem, prone to imbalance and algal blooms: Traditional construction methods often focus on landscaping or simple aquatic plant configurations, lacking a complete "producer-consumer-decomposer" food chain design. The system has poor resistance to disturbances and is highly susceptible to algal blooms under nutrient input (such as non-point source pollution, fallen leaves) or temperature changes, leading to water turbidity and decreased transparency, i.e., degrading from "clear water" to "turbid water".

[0003] 2. High maintenance costs due to reliance on external intervention: To maintain water quality, existing technologies often rely on strong external intervention methods such as physical filtration, chemical dosing, or frequent water changes. These methods are energy-intensive, chemical agents may cause secondary pollution and damage to native ecosystems, and maintenance costs are high.

[0004] 3. Lack of systematic design and single function: Existing patents mostly focus on a single function, such as enhanced purification, plant configuration, or fish farming. There is a lack of a method to plan the terrain design, substrate configuration, plant-animal-microbe synergy, and hydraulic circulation as a whole system, making it difficult to achieve purification effect, landscape effect, and ecological stability simultaneously.

[0005] 4. Insufficient targeting of small-scale, enclosed / semi-enclosed water bodies: Treatment methods for rivers and lakes are difficult to directly apply to "micro-wetlands" with weak water exchange capacity and small environmental capacity. Existing technologies often overlook the characteristics of micro-wetlands, such as short hydrological cycles and significant boundary effects, leading to the technology being "unsuitable for local conditions".

[0006] Therefore, there is an urgent need for an ecological construction method that is tailored to the characteristics of small wetlands, can establish strong ecological inhibition from within the system, and achieve low-cost, long-term self-sustaining clear water status. Summary of the Invention

[0007] The purpose of this invention is to provide an ecosystem construction method suitable for small wetlands, which can achieve low-cost, long-term self-sustaining clear water status and ecological stability.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for constructing an ecosystem suitable for small wetlands, comprising the following steps: (1) The target micro-wetland is transformed to construct a continuous gradient terrain of tidal flat area - submerged area - shallow water area - deep water area - shallow water area - submerged area - tidal flat area, and a composite functional matrix is ​​laid in the tidal flat area; (2) Plant floating-leaved plants in shallow water areas, emergent plants in submerged areas, and submerged plants in deep water areas; (3) Filter-feeding shellfish, carnivorous fish and omnivorous fish are released into the deep water area; (4) Apply microbial agents to the surface of the composite functional substrate and the roots of emergent plants; (5) Regularly monitor water quality to maintain ecosystem stability.

[0009] Preferably, in step (1), the tidal flat area accounts for 8-12% of the total wetland area; the submerged area accounts for 8-12% of the total wetland area, and the water depth of the submerged area is 0.01-0.3m; the shallow water area accounts for 8-12% of the total wetland area, and the water depth of the shallow water area is 0.3-0.8m; the deep water area accounts for 65-75% of the total wetland area, and the water depth of the deep water area is 0.8-1.5m.

[0010] Preferably, the composite functional matrix in step (1) is composed of zeolite, ceramsite, and biochar in a mass ratio of (3-8):(1-5):(1-3), wherein the particle size of the zeolite, ceramsite, and biochar is 2-5 cm; and the laying thickness of the composite functional matrix is ​​10-20 cm.

[0011] Preferably, the floating-leaved plant in step (2) is water lily and / or water snowflake; the emergent plant is yellow iris and / or reed; and the submerged plant is any two or more of the following: Vallisneria natans, Hydrilla verticillata, and Myriophyllum spicatum.

[0012] Preferably, when the floating-leaved plants are water lilies and water snowflakes, the planting ratio of water lilies and water snowflakes is 1:(0.5-1.5).

[0013] Preferably, when the emergent plants are yellow iris and reed, the planting ratio of yellow iris and reed is (5-8):3.

[0014] Preferably, when the submerged plants are *Vallisneria natans*, *Hydrilla verticillata*, and *Myriophyllum sp.*, the planting ratio of *Vallisneria natans*, *Hydrilla verticillata*, and *Myriophyllum sp.* is (5-9):(1-5):1.

[0015] Preferably, the planting density of the floating-leaved plants in step (2) is 1-3 plants / m². 2 The floating-leaved plants occupy 10-20% of the total area of ​​the shallow water area.

[0016] Preferably, the planting density of the emergent plants is 18-22 plants / m².2 The area planted with emergent plants accounts for 40-60% of the total area of ​​the submerged zone.

[0017] Preferably, the planting density of the submerged plants is 90-100 plants / m². 2 The submerged plants account for 70-80% of the total area of ​​the deep water zone.

[0018] Preferably, the filter-feeding shellfish in step (3) includes the toothless mussel, the carnivorous fish is mandarin fish and / or snakehead, and the omnivorous fish includes blunt snout bream.

[0019] Preferably, the stocking density of the filter-feeding shellfish is 1-3 per m³. 2 The stocking density of the carnivorous fish is 1-3 fish / m². 2 The stocking density of the omnivorous fish is 1-2 fish / m². 2 .

[0020] Preferably, when the carnivorous fish are mandarin fish and snakehead fish, the stocking ratio of mandarin fish and snakehead fish is 1:(0.5-1.5).

[0021] Preferably, the microbial agent in step (4) is a short-cut nitrification-denitrification polyphosphate-accumulating agent, and the application rate on the surface of the composite functional matrix is ​​1-2 g / m². 3 The application rate for emergent plant roots is 1.5-2.5 g / m³. 3 .

[0022] By adopting the above technical solution, the present invention has the following beneficial effects: This invention's technical solution involves topographic modification of a target small wetland, followed by the introduction of aquatic plants and animals in stages and proportions according to the principles of niche complementarity and food chain inhibition. Microorganisms are then inoculated for system enhancement, and finally, water quality monitoring is conducted on the constructed ecosystem. This effectively achieves the goal of maintaining clear water and ecological stability at low cost over the long term. The composite functional matrix described in this invention can rapidly construct a microbial attachment carrier, pre-preparing a growth environment for nitrogen and phosphorus removal functional bacteria, effectively solving the core problems of insufficient microbial systems and weak pollutant degradation capacity in artificial new water bodies. Furthermore, the ecosystem construction method described in this invention is specifically tailored for small wetlands. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall zoning structure of the small wetland steady-state clear water ecosystem described in Experimental Example 1 of the present invention. Figure 1 In the diagram, 1 represents tidal flats, 2 represents submerged areas, 3 represents shallow water areas, 4 represents deep water areas, 5 represents emergent plants, 6 represents floating-leaved plants, and 7 represents submerged plants. Detailed Implementation

[0024] This invention provides a method for constructing an ecosystem suitable for small wetlands, comprising the following steps: (1) The target micro-wetland is transformed to construct a continuous gradient terrain of tidal flat area - submerged area - shallow water area - deep water area - shallow water area - submerged area - tidal flat area, and a composite functional matrix is ​​laid in the tidal flat area; (2) Plant floating-leaved plants in shallow water areas, emergent plants in submerged areas, and submerged plants in deep water areas; (3) Filter-feeding shellfish, carnivorous fish and omnivorous fish are released into the deep water area; (4) Apply microbial agents to the surface of the composite functional substrate and the roots of emergent plants; (5) Regularly monitor water quality to maintain ecosystem stability.

[0025] In this invention, the target micro-wetland is modified to construct a continuous gradient terrain of tidal flat area - submerged area - shallow water area - deep water area - shallow water area - submerged area - tidal flat area.

[0026] In this invention, the tidal flat area accounts for 8-12% of the total wetland area, more preferably 9-11%, and even more preferably 10%. The submerged area accounts for 8-12% of the total wetland area, more preferably 9-11%, and even more preferably 10%; the water depth of the submerged area is preferably 0.01-0.3m. The shallow water area accounts for 8-12% of the total wetland area, more preferably 9-11%, and even more preferably 10%; the water depth of the shallow water area is preferably 0.3-0.8m. The deep water area accounts for 65-75% of the total wetland area, more preferably 68-72%, and even more preferably 70%; the water depth of the deep water area is preferably 0.8-1.5m.

[0027] In this invention, the slope ratio of the deep water area is preferably 1:2.5, and the slope is protected by ecological geotextile to prevent rainwater erosion and soil loss, forming a stable deep-water low-temperature still water layer; the slope of the shallow water area has a gentle transition to avoid water turbulence and disturbance; the tidal flat area is designed to create a natural periodic wet and dry alternation zone, which is suitable for the hydrological characteristics of rainwater storage and shallow exposure on sunny days.

[0028] In this invention, after the terrain modification is completed, a seepage-proof layer is laid throughout the area to prevent water leakage and ensure the stability of the water level in the sealed water body. The seepage-proof layer of this invention comprises two layers: a 6mm thick bentonite liner and a 2mm thick double-sided HDPE geomembrane. Preferably, a 5cm layer of original excavated soil is laid on top of the seepage-proof layer to provide a basic carrier for the growth of microorganisms and plants.

[0029] In this invention, a composite functional matrix is ​​laid in the tidal flat area. The composite functional matrix consists of zeolite, ceramsite, and biochar. The preferred mass ratio of zeolite, ceramsite, and biochar is (3-8):(1-5):(1-3), further preferably (4-6):(2-4):(1.5-2.5), and even more preferably 5:3:2.

[0030] In this invention, the particle size of the zeolite, ceramsite, and biochar is preferably 2-5 cm, more preferably 2.5-4.5 cm, and even more preferably 3 cm; the thickness of the composite functional matrix is ​​preferably 10-20 cm, more preferably 12-18 cm, and even more preferably 15 cm.

[0031] In this invention, the composite functional matrix can rapidly construct a microbial attachment carrier, pre-preparing a growth environment for denitrification and phosphorus removal functional bacteria, effectively solving the core problems of the lack of microbial systems in artificial new water bodies and weak pollutant degradation capabilities. In this invention, floating-leaved plants are planted in shallow water areas, emergent plants in submerged areas, and submerged plants in deep water areas. The planting sequence follows the principle of "submerged first, then emergent, then floating-leaved," ensuring orderly planting and stable growth of vegetation.

[0032] In this invention, the floating-leaved plant in step (2) is water lily and / or water snowflake; the emergent plant is yellow iris and / or reed; and the submerged plant is any two or more of the following: Vallisneria natans, Hydrilla verticillata, and Myriophyllum spicatum.

[0033] In this invention, when the floating-leaved plants are water lilies and water snowflakes, the planting ratio of water lilies and water snowflakes is preferably 1:(0.5-1.5), more preferably 1:(0.8-1.2), and even more preferably 1:1.

[0034] In this invention, the planting density of the floating-leaved plants in step (2) is preferably 1-3 plants / m². 2 A further preferred ratio is 2 plants / m². 2 The planting area of ​​the floating-leaved plants accounts for 10-20% of the total area of ​​the shallow water area, more preferably 12-18%, and even more preferably 15%.

[0035] In this invention, when the emergent plants are yellow iris and reed, the planting ratio of yellow iris and reed is preferably (5-8):3, further preferably (6-7.5):3, and even more preferably 7:3.

[0036] In this invention, the preferred planting density of the emergent plants is 18-22 plants / m². 2 A further preferred value is 19-21 plants / m². 2A further preferred value is 20 plants / m². 2 The area of ​​emergent plants is 40-60% of the total area of ​​the shallow water area, more preferably 45-55%, and even more preferably 50%.

[0037] In this invention, when the submerged plants are *Vallisneria natans*, *Hydrilla verticillata*, and *Myriophyllum spicatum*, the planting ratio of *Vallisneria natans*, *Hydrilla verticillata*, and *Myriophyllum spicatum* is preferably (5-9):(1-5):1, further preferably (6-8):(2-4):1, and even more preferably 7:3:1.

[0038] In this invention, the preferred planting density of the submerged plants is 90-100 plants / m². 2 A further preferred value is 92-98 plants / m². 2 A further preferred value is 95 plants / m². 2 The submerged plants account for 70-80% of the total area of ​​the deep water zone, more preferably 72-78%, and even more preferably 75%.

[0039] In this invention, filter-feeding shellfish, carnivorous fish, and omnivorous fish are introduced into deep water areas. The filter-feeding shellfish can directly filter suspended algae and organic debris; the carnivorous fish can control the number of small fish and insect larvae, protect large zooplankton, and form an inhibitory food chain of "carnivorous fish → small fish / insects → large zooplankton → phytoplankton"; and the omnivorous fish can forage for submerged plants, controlling their excessive growth.

[0040] In this invention, the filter-feeding mollusks include the toothless mussel, the carnivorous fish are mandarin fish and / or snakehead fish, and the omnivorous fish include blunt snout bream.

[0041] In this invention, the preferred stocking density of the filter-feeding shellfish is 1-3 per m³. 2 A further preferred value is 2 per m 2 The preferred stocking density of the carnivorous fish is 1-3 fish / m³. 2 A further preferred ratio is 2 tails / m 2 The preferred stocking density for the omnivorous fish is 1-2 fish / m². 2 A further preferred ratio is 1 tail / m 2 .

[0042] In this invention, when the carnivorous fish are mandarin fish and snakehead fish, the preferred ratio of mandarin fish to snakehead fish is 1:(0.5-1.5), further preferably 1:(0.8-1.2), and even more preferably 1:1.

[0043] In this invention, microbial agents are applied to the surface of the composite functional matrix and the roots of emergent plants. The microbial agents used in this invention are preferably short-cut nitrifying-denitrifying polyphosphate-accumulating agents (effective viable count ≥ 3 billion CFU / g (solid)), purchased from Bioway Biotechnology (Guangdong) Co., Ltd.

[0044] In this invention, the preferred application amount on the surface of the composite functional matrix is ​​1-2 g / m². 3 Further preferred values ​​are 1.2-1.8 g / m³. 3 A further preferred value is 1.5g / m 3 The application rate to the roots of emergent plants is 1.5-2.5 g / m³. 3 Further preferred values ​​are 1.8-2.2 g / m³. 3 A further preferred value is 2g / m 3 .

[0045] In this invention, during the stabilization period of 3-6 months after the system is built, key indicators (transparency, chlorophyll a, ammonia nitrogen) are monitored, and fine-tuning is carried out by adjusting the biological density and circulation frequency until the system reaches a stable "clear water state".

[0046] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0047] Example 1

[0048] An ecosystem construction method suitable for small wetlands, comprising the following steps: (1) The target micro-wetland is modified to construct a continuous gradient terrain of tidal flat area - submerged area - shallow water area - deep water area - shallow water area - submerged area - tidal flat area. The tidal flat area accounts for 10% of the total wetland area; the submerged area accounts for 10% of the total wetland area with a water depth of 0.01-0.3m; the shallow water area accounts for 10% of the total wetland area with a water depth of 0.3-0.8m; the deep water area accounts for 70% of the total wetland area with a water depth of 0.8-1.5m; a seepage-proof layer is laid throughout the area. The seepage-proof layer consists of two layers: a 6mm thick bentonite liner and a 2mm thick double-sided HDPE geomembrane; a 5cm original excavated soil protective layer is laid on top of the seepage-proof layer. A 15cm thick composite functional matrix consisting of zeolite, ceramsite, and biochar in a mass ratio of 5:3:2 is laid in the tidal flat area. The particle size of the zeolite, ceramsite, and biochar is 3cm. (2) Plant water lilies and water snowflakes in a 1:1 ratio in shallow water areas, with a planting density of 2 plants / m². 2 The planting area accounts for 15% of the total shallow water area; in the submerged area, yellow iris and reeds are planted in a ratio of 7:3, with a planting density of 20 plants / m².2 The planting area accounts for 50% of the total shallow water area, while in the deep water area, the planting ratio of Vallisneria natans, Hydrilla verticillata, and Myriophyllum spicatum is 7:2:1, with a planting density of 95 plants / m². 2 The planting area accounts for 75% of the total submerged area; (3) In deep water areas, according to 2 units / m 2 The density of *Odontoceras dorsiflora* mussels was set at 2 mussels / m. 2 The density of mandarin fish and snakehead fish is 1 fish / m 2 The density of crucian carp is set at 1:1; the ratio of mandarin fish to snakehead is 1:1. (4) Apply 1.5 g / m² to the surface of the composite functional matrix. 3 Apply short-cut nitrification-denitrification polyphosphate-accumulating bacteria at a rate of 2 g / m² on the root system of emergent plants. 3 Apply short-cut nitrifying-denitrifying polyphosphate-accumulating bacteria in appropriate amounts; (5) During the stabilization period of 3-6 months after the system is built, monitor key indicators such as transparency, chlorophyll a, and ammonia nitrogen. Make fine adjustments by adjusting the biological density and circulation frequency until the system reaches a stable "clear water state".

[0049] Example 2

[0050] An ecosystem construction method suitable for small wetlands, comprising the following steps: (1) The target micro-wetland is transformed by terrain modification to construct a continuous gradient terrain of tidal flat area - submerged area - shallow water area - deep water area - shallow water area - submerged area - tidal flat area. The tidal flat area accounts for 8% of the total wetland area; the submerged area accounts for 12% of the total wetland area with a water depth of 0.01-0.3m; the shallow water area accounts for 8% of the total wetland area with a water depth of 0.3-0.8m; the deep water area accounts for 72% of the total wetland area with a water depth of 0.8-1.5m; a seepage-proof layer is laid throughout the area. The seepage-proof layer consists of two layers: a 6mm thick bentonite liner and a 2mm thick double-sided HDPE geomembrane; a 5cm original excavated soil protective layer is laid on top of the seepage-proof layer. A 10cm thick composite functional matrix consisting of zeolite, ceramsite, and biochar in a mass ratio of 8:1:3 is laid in the tidal flat area. The particle size of each of the zeolite, ceramsite, and biochar is 2cm. (2) Water lilies and water snowflakes were planted in a ratio of 1:1.5 in shallow water areas, with a planting density of 3 plants / m². 2 The planting area accounts for 20% of the total shallow water area; in the submerged area, yellow iris and reeds are planted in a 5:3 ratio, with a planting density of 22 plants / m². 2 The planting area accounts for 60% of the total shallow water area, while in the deep water area, the planting ratio of Vallisneria natans, Hydrilla verticillata, and Myriophyllum spicatum is 9:1:1, with a planting density of 90 plants / m². 2The planting area accounts for 70% of the total submerged area; (3) In deep water areas, according to 1 unit / m 2 The density of *Odontoceras dorsiflora* mussels was set at 2 mussels / m. 2 The density of mandarin fish and snakehead fish is 1 fish / m 2 The density of crucian carp is set at 1:1.5; the ratio of mandarin fish to snakehead is 1:1.5. (4) Apply 1g / m to the surface of the composite functional matrix. 3 Apply short-cut nitrification-denitrification polyphosphate-accumulating bacteria at a rate of 2.5 g / m² on the root system of emergent plants. 3 Apply short-cut nitrifying-denitrifying polyphosphate-accumulating bacteria in appropriate amounts; (5) During the stabilization period of 3-6 months after the system is built, monitor key indicators such as transparency, chlorophyll a, and ammonia nitrogen. Make fine adjustments by adjusting the biological density and circulation frequency until the system reaches a stable "clear water state".

[0051] Example 3

[0052] An ecosystem construction method suitable for small wetlands, comprising the following steps: (1) The target micro-wetland is modified to construct a continuous gradient terrain of tidal flat area - submerged area - shallow water area - deep water area - shallow water area - submerged area - tidal flat area. The tidal flat area accounts for 12% of the total wetland area; the submerged area accounts for 8% of the total wetland area with a water depth of 0.01-0.3m; the shallow water area accounts for 12% of the total wetland area with a water depth of 0.3-0.8m; the deep water area accounts for 68% of the total wetland area with a water depth of 0.8-1.5m; a seepage-proof layer is laid throughout the area. The seepage-proof layer consists of two layers: a 6mm thick bentonite liner and a 2mm thick double-sided HDPE geomembrane; a 5cm original excavated soil protective layer is laid on top of the seepage-proof layer. A 20cm thick composite functional matrix consisting of zeolite, ceramsite, and biochar in a mass ratio of 3:5:1 is laid in the tidal flat area. The particle size of the zeolite, ceramsite, and biochar is 5cm. (2) Water lilies and water snowflakes were planted in a ratio of 1:0.5 in shallow water areas, with a planting density of 1 plant / m². 2 The planting area accounts for 10% of the total shallow water area; in the submerged area, yellow iris and reeds are planted in a ratio of 8:3, with a planting density of 18 plants / m². 2 The planting area accounts for 40% of the total shallow water area. In the deep water area, the planting ratio of Vallisneria natans, Hydrilla verticillata, and Myriophyllum spicatum is 5:5:1, with a planting density of 100 plants / m². 2 The planting area accounts for 80% of the total area of ​​the submerged area; (3) In deep water areas, according to 3 units / m 2 The density of *Odontoceras dorsiflora* mussels was set at 2 mussels / m. 2The density of mandarin fish and snakehead fish is 2 fish / m 2 The density of crucian carp is set at 1:0.5; the ratio of mandarin fish to snakehead is 1:0.5. (4) Apply 2g / m to the surface of the composite functional matrix. 3 Apply short-cut nitrification-denitrification polyphosphate-accumulating bacteria at a rate of 1.5 g / m² on the root system of emergent plants. 3 Apply short-cut nitrifying-denitrifying polyphosphate-accumulating bacteria in appropriate amounts; (5) During the stabilization period of 3-6 months after the system is built, monitor key indicators such as transparency, chlorophyll a, and ammonia nitrogen. Make fine adjustments by adjusting the biological density and circulation frequency until the system reaches a stable "clear water state".

[0053] Experimental Example 1

[0054] Manual excavation and closure of 1500m 2 Methods for constructing clear water ecosystems in small wetlands

[0055] This experimental case study selected a small, enclosed wetland artificially excavated within Nanjing City. The site had no existing water body, no natural hydrological exchange, and no old, polluted sediment. It was a newly constructed urban and rural supporting landscape ecological water body with a total excavated water area of ​​1500 m². 2 This is a completely enclosed, stagnant water body, receiving only rainfall and minor non-point source runoff from the surrounding area. This enclosed water body suffers from: poor water flow, weak reoxygenation capacity, and the absence of natural ecological communities. After construction, it is prone to problems such as water stagnation, algae growth, gradual eutrophication, and water turbidity. This experimental example utilizes the technical system of this invention to construct a novel standardized ecological system (e.g., Figure 1 This method is adapted to the characteristics of artificially excavated and enclosed small wetland water bodies. The specific steps are as follows: (1) On-site survey and customized solution design A comprehensive survey of the artificially excavated site revealed no existing water bodies, no natural hydrological exchange, and no old, contaminated sediment. This was combined with a 1500m... 2 Due to the characteristics of enclosed aquatic environments such as small environmental capacity, weak self-purification ability, and susceptibility to eutrophication, customized gradient habitat zoning parameters were implemented: deep water area 1050m². 2 (70%), shallow water area 150m 2 (10%), immersion zone 150m 2 (10%), 150m mudflats 2 (10%), matching 1500m 2 The ecological carrying capacity threshold of the water body is used to determine the biological release density, substrate ratio, and hydraulic operation parameters.

[0056] (2) Gradient habitat setting

[0057] Based on design parameters, precise manual excavation and trimming are carried out to create a continuous gradient habitat, adapting to the ecological needs of the enclosed water body: In deep water areas, the water depth is trimmed to 0.8-1.5m, with a slope ratio of 1:2.5. Ecological geotextile is used for slope protection to prevent rainwater erosion and soil loss, forming a stable, deep-water, low-temperature still water layer; in shallow water areas, the water depth is trimmed to 0.3-0.8m, with a gentle slope transition to avoid water turbulence; in submerged areas, the water depth is 0.01-0.3m; in tidal flat areas, a natural periodic wet-dry alternation zone is created, adapting to the hydrological characteristics of rainfall water storage and sunny-day shallow exposure. After manual excavation, a seepage-proof layer is laid throughout the area to prevent water leakage and ensure stable water levels in the enclosed water body. The seepage-proof layer consists of two layers: a 6mm thick bentonite liner and a 2mm thick double-sided HDPE geomembrane. A 5cm layer of the original excavated soil is laid on top of the seepage-proof layer to provide a basic carrier for microbial and plant growth.

[0058] A composite functional substrate was laid in the core purification area of ​​the tidal flat. The substrate consisted of zeolite, ceramsite, and biochar in a mass ratio of 5:3:2, with a thickness of 15cm. The substrate particle size was controlled at 3.5cm, and the porosity was ≥40%. Since the newly excavated water body lacked indigenous microbial communities, this composite functional substrate could quickly establish a carrier for microbial attachment, pre-preparing a growth environment for denitrification and phosphorus removal functional bacteria. This effectively solved the core problems of the lack of microbial systems and weak pollutant degradation capacity in artificial new water bodies. Compared with a single substrate, the inhibition efficiency of nitrogen and phosphorus enrichment in closed water bodies was improved by more than 35%.

[0059] (3) Constructing plant systems by zone

[0060] A zoned and batch planting method was adopted, following the planting sequence of "submerged first, then emerging, and finally floating leaves" to ensure orderly planting and stable growth of vegetation. In the deep water area, *Vallisneria natans*, *Hydrilla verticillata*, and *Myriophyllum spicatum* were planted throughout, with a mixed planting ratio of 7:2:1 and a planting density of 100 plants / m². 2 The planting area accounts for 75% of the total area of ​​the deep water zone, inhibiting the photosynthesis of bottom algae and absorbing nutrients from the bottom of the water. Yellow irises and reeds are planted at the edges of the shallow water zone and the submerged zone, with a mixed planting ratio of 7:3, a plant spacing of 30cm, and a planting density of 20 plants / m². 2 The planting area accounts for 50% of the total shallow water area; water lilies and water chestnuts are planted at a depth of 0.4m in the shallow water area, with a planting ratio of 1:1 and a planting density of 2 plants / m². 2 The planting area accounts for 15% of the total area of ​​the shallow water area, forming a three-dimensional vegetation barrier with upper shading, middle purification, and bottom nitrogen fixation.

[0061] (4) Construction of consumer communities and decomposer systems

[0062] After the vegetation has been established for 30 days and the survival rate has reached over 90%, various consumer species will be gradually introduced into the deep water area, and decomposers will be inoculated to establish a complete food chain. Filter-feeding mollusks, specifically *Anodon dorsiflorus*, were introduced into the deep-water area at a biomass of 2 mollusks / m³. 2 It is used for efficient filtration of suspended algae and organic debris in water, rapidly improving water transparency; 1 mandarin fish is released per m³. 2 1 snakehead fish / m 2 To control the populations of small omnivorous fish and aquatic insect larvae in the water, prevent the over-predation of large zooplankton, and stabilize algae to suppress the food chain; release one 10cm long blunt snout bream per m. 2 To prevent the excessive growth of submerged plants; Because the newly excavated water body lacks indigenous functional microorganisms, a concentration of 1.5 g / m² is applied to the surface of the composite functional matrix. 3 Spray with short-cut nitrification-denitrification polyphosphate-accumulating bacteria, and apply to the roots of emergent plants at a rate of 2 g / m². 3 Spraying short-cut nitrification-denitrification polyphosphate-accumulating bacteria once a month for four consecutive months rapidly cultivates a stable microbial decomposition system, achieving efficient mineralization and decomposition of pollutants in water and substrates, and making up for the shortcomings of the decomposition function of new water bodies.

[0063] (5) System steady-state monitoring and refined regulation

[0064] After the system is built, it will enter a 6-month stable operation and maintenance period. Every half month, core indicators such as water transparency, chlorophyll a, ammonia nitrogen, total phosphorus, and dissolved oxygen will be monitored. Based on changes in water quality and the growth of submerged plants, precise control will be implemented. If a large number of submerged plants die, they will be replanted in a timely manner according to the aforementioned ratio.

[0065] After a 6-month system stabilization period, the total nitrogen concentration in the water was maintained at 1.05-1.5 mg / L, the total phosphorus concentration at 35.6-50.2 μg / L, the chlorophyll a concentration at 10-15 μg / L, the transparency-to-depth ratio at 0.9-1.0, and the submerged plant biomass at 3.6 kg / m³. 2 The concentrations of total nitrogen, total phosphorus, and chlorophyll a were determined according to the corresponding methods in the fourth edition of "Methods for Monitoring and Analysis of Water and Wastewater"; transparency was measured using the transparency disc method; and the biomass of submerged plants was determined through an opening of 0.5m. 2 The submerged plant grab bucket was evaluated.

[0066] In summary, the technical solution of this invention achieves the goal of maintaining clear water and ecological stability in small wetlands at low cost and in the long term by modifying the terrain of the target small wetland, introducing aquatic plants and animals in stages and proportions according to the principles of ecological niche complementarity and food chain inhibition, inoculating microorganisms for system enhancement, and finally monitoring the water quality of the constructed ecosystem.

[0067] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for constructing an ecosystem suitable for small wetlands, characterized in that, Includes the following steps: (1) The target micro-wetland is transformed to construct a continuous gradient terrain of tidal flat area - submerged area - shallow water area - deep water area - shallow water area - submerged area - tidal flat area, and a composite functional matrix is ​​laid in the tidal flat area; (2) Plant floating-leaved plants in shallow water areas, emergent plants in submerged areas, and submerged plants in deep water areas; (3) Filter-feeding shellfish, carnivorous fish and omnivorous fish are released into the deep water area; (4) Apply microbial agents to the surface of the composite functional substrate and the roots of emergent plants; (5) Regularly monitor water quality to maintain ecosystem stability.

2. The ecosystem construction method according to claim 1, characterized in that, The tidal flat area mentioned in step (1) accounts for 8-12% of the total wetland area; the submerged area accounts for 8-12% of the total wetland area, and the water depth of the submerged area is 0.01-0.3m; The shallow water area accounts for 8-12% of the total wetland area, and the water depth of the shallow water area is 0.3-0.8m; The deep water area accounts for 65-75% of the total wetland area, and the water depth of the deep water area is 0.8-1.5m.

3. The ecosystem construction method according to claim 1, characterized in that, The composite functional matrix in step (1) is composed of zeolite, ceramsite and biochar in a mass ratio of (3-8):(1-5):(1-3), wherein the particle size of the zeolite, ceramsite and biochar is 2-5 cm; and the laying thickness of the composite functional matrix is ​​10-20 cm.

4. The ecosystem construction method according to claim 1, characterized in that, The floating-leaved plant in step (2) is water lily and / or water snowflake; the emergent plant is yellow iris and / or reed; the submerged plant is any two or more of the following: Vallisneria natans, Hydrilla verticillata, and Myriophyllum spicatum.

5. The ecosystem construction method according to claim 4, characterized in that, When the floating-leaved plants are water lilies and water snowflakes, the planting ratio of water lilies and water snowflakes is 1:(0.5-1.5); When the emergent plants are yellow iris and reed, the planting ratio of yellow iris and reed is (5-8):

3. When the submerged plants are *Vallisneria natans*, *Hydrilla verticillata*, and *Myriophyllum spicatum*, the planting ratio of *Vallisneria natans*, *Hydrilla verticillata*, and *Myriophyllum spicatum* is (5-9):(1-5):

1.

6. The ecosystem construction method according to claim 1, characterized in that, The planting density of the floating-leaved plants in step (2) is 1-3 plants / m². 2 The planting area of ​​the floating-leaved plants accounts for 10-20% of the total area of ​​the shallow water area; The planting density of the emergent plants is 18-22 plants / m². 2 The area planted with emergent plants accounts for 40-60% of the total submerged area; The planting density of the submerged plants is 90-100 plants / m². 2 The submerged plants account for 70-80% of the total area of ​​the deep water zone.

7. The ecosystem construction method according to claim 1, characterized in that, The filter-feeding mollusks in step (3) include the toothless mussel, the carnivorous fish are mandarin fish and / or snakehead fish, and the omnivorous fish include blunt snout bream; The stocking density of the filter-feeding shellfish is 1-3 per m³. 2 The stocking density of the carnivorous fish is 1-3 fish / m². 2 The stocking density of the omnivorous fish is 1-2 fish / m². 2 .

8. The ecosystem construction method according to claim 7, characterized in that, When the carnivorous fish are mandarin fish and snakehead fish, the stocking ratio of mandarin fish and snakehead fish is 1:(0.5-1.5).

9. The ecosystem construction method according to claim 1, characterized in that, The microbial agent mentioned in step (4) is a short-cut nitrification-denitrification polyphosphate-accumulating agent, and the application rate on the surface of the composite functional matrix is ​​1-2 g / m². 3 The application rate for emergent plant roots is 1.5-2.5 g / m³. 3 .

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