Method for promoting pollution reduction, carbon sequestration and sink increase of lakes through combination of bottom groove construction and silver carps

Abstract

The invention discloses a method for promoting lake pollution reduction, carbon sequestration and sink increase through combination of bottom groove construction and silver carp, which comprises the following steps: constructing a bottom groove downwards at the bottom of a lake in a range of 50-100m from lakeside wetland water to an outer edge water area of a middle and large lake; one or more closed silver carp captive rearing areas are formed at the position 120 m away from the lake shoreline to the lakeside wetland water towards the outer edge water area, and then silver carps are stocked in the silver carp captive rearing areas. Wetland plants grow to absorb water nutritive salt, atmosphere and water carbon dioxide and bicarbonate, and a large amount of carbon can be fixed in the plants; lake algae gather in a lakeside water area under the action of wind power, so that the algae filtering and feeding efficiency of silver carps captive on the lakeside is improved, and nitrogen, phosphorus, carbon and the like are fixed in fish bodies during fish growth; aquatic plant litter chippings and silver carp feces are brought into the constructed bottom groove by lake flow and stormy waves and are mutually buried with silt and other particles in the sedimentation process to form nitrogen phosphorus and carbon burying, and therefore the effects of reducing pollution, fixing carbon and increasing sink in lakes are achieved. The method can significantly improve the pollution-reducing, carbon-sequestration and sink-increasing effects of lakes.

Description

Technical Field

[0001] The present invention belongs to the field of water ecological environment, and particularly relates to a method for jointly promoting pollution reduction, carbon fixation and carbon sink enhancement in lakes by constructing bottom troughs and controlling algae with silver carp. Background Art

[0002] The increase in greenhouse gas emissions has caused global warming and led to an increase in extreme weather and disasters, which is a major environmental problem at present. The frequent occurrence of lake eutrophication and algal blooms is also a prominent environmental problem. Therefore, pollution reduction, carbon fixation and carbon sink enhancement in lakes are strong global technological demands.

[0003] The carbon flux received, stored and transported by inland waters (including lakes) reaches 5.1 PgC / yr, accounting for 60% of the annual global terrestrial carbon fixation flux; while the carbon emissions to the atmosphere are only 3.9 PgC / yr. Lakes account for 87% of the area of inland waters and contribute the vast majority of the primary productivity of inland waters (Kirk, 2010), making a significant contribution to carbon fixation in the basin. The total primary productivity of global lakes can reach 1.3 PgC / yr, and the amount of organic carbon buried through lakes every year is about 25 - 50% of the amount buried in the ocean. Therefore, lakes are an important link in the global carbon cycle process.

[0004] Wetlands are the "kidneys of the earth". A large number of studies have shown that the growth of wetland plants in the lake littoral zone can absorb a large amount of nutrients in the water body and reduce nitrogen and phosphorus pollution in lakes; plant photosynthesis absorbs a large amount of CO2 and bicarbonate, fixing a large amount of carbon in the plants; wetland plants promote the establishment of beneficial environmental microbial communities and degrade organic pollutants in lakes. Compared with the area where aquatic plants grow, studies have shown that the CH4 content in the turbid water area dominated by phytoplankton is higher, and the accumulation and burial of inert organic carbon in the plant residues and litter in the aquatic plant area are higher, and the organic matter in the sediments of this area is often significantly higher than that in other waters. The above studies show that wetlands have strong pollution reduction and carbon fixation capabilities. However, some lake wetlands are polluted and degraded, and the purification function and carbon burial capacity of wetlands have declined, urgently requiring the development of technologies to improve pollution reduction, carbon fixation and carbon sink enhancement in lake wetlands.

[0005] In the prior art, CN202410657136.3 discloses a method for preparing wetland matrix by ceramsite to enhance carbon sequestration, which fixes carbon dioxide in the form of carbonate minerals in the ceramsite particles through carbonization modification of the ceramsite. CN202411556941.3 discloses a method for abnormal detection of hydrological sequence data based on cloud computing, which can improve the pertinence of data analysis and processing for wetland carbon sequestration and sink monitoring and regulation. CN202411314830.1 discloses a method for predicting the long-term trend of water body carbon emissions based on Bayesian additive regression tree, which provides an effective way for the evaluation of water body carbon emission level and long-term trend prediction. CN202311563038.5 discloses a device and method for in-situ enhancing carbon sequestration and sink of lake sediment, which can be used for low-carbon and stable disposal of lake sediment. In addition, there are some prior arts that add mineral powder to the water body and install relatively complex devices to increase the carbon sink effect of lakes. However, the current prior arts related to lake carbon sequestration and sink focus on detection and evaluation, adding preparations, installing devices, increasing aquatic plants, etc., lacking technologies that can be widely applied, have low cost, and are physical and biological green ecology technologies. Summary of the Invention

[0006] In view of the above problems, the present invention provides a method for promoting lake pollution reduction, carbon sequestration and sink enhancement by combining bottom groove construction and silver carp, which can solve the technical problems that the carbon sink function of existing lakeside wetlands is weakened or even lost, and traditional ecological restoration technologies and wetland management means cannot effectively improve pollution reduction, carbon sequestration and sink enhancement.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for promoting lake pollution reduction, carbon sequestration and sink enhancement by combining bottom groove construction and silver carp, comprising the following steps:

[0009] (1) Build a bottom groove downward on the lake bottom within a range of 50 - 100 m from the water of the lakeside wetland to the outer edge water area of a medium or large-sized lake, and the bottom groove is parallel to the lake shoreline;

[0010] (2) Form one or more enclosed silver carp captive areas by laying fishing nets from the lake shoreline to 120 m from the water of the lakeside wetland to the outer edge water area, and then release silver carp in the silver carp captive areas.

[0011] Further, in step (1), the width of the bottom groove is 3 - 5 m, and the depth is 2 - 4 m.

[0012] Further, in step (1), the length of the bottom groove is the same as or slightly less than the length of the lakeside wetland.

[0013] Further, step (1) further includes the step of regularly dredging and cleaning the bottom groove. More preferably, the dredging and cleaning is carried out once every 3 years.

[0014] The polluted sediment rich in nitrogen, phosphorus and organic carbon deposited in the excavated bottom trough generally accumulates deeper after about 3 years, the pollutant and carbon burial effects weaken, and dredging and sediment cleaning work is carried out on the deep trough every 3 years, which can further increase the pollutant reduction, carbon fixation and carbon sink enhancement ability of the system.

[0015] Furthermore, there are two enclosure nets in step (2), and the distance between the two enclosure nets is 2 m.

[0016] Furthermore, the length of the silver carp captive area in step (2) is 100 - 1000 m. The total length of the silver carp captive area along the lake shoreline is close to the length of the wetland. The enclosure net and the lake shoreline enclose a closed silver carp captive area to prevent fish from escaping.

[0017] Furthermore, the stocking density of the silver carp is 50 g - 150 g / m 2 , and the silver carp is 0.3 - 0.5 kg per fish.

[0018] Furthermore, there are multiple silver carp captive areas in step (2), and the total length of all the areas where the silver carp captive areas are located along the lake shoreline is equal to or slightly less than the length of the wetland, and there is an interval between adjacent silver carp captive areas. The silver carp captive area can reduce the algae in the near-shore water body, especially the bloom cyanobacteria. The purpose of establishing multiple spaced silver carp captive areas is to facilitate the entry and exit of wetland management boats into the wetland, and at the same time is conducive to the monitoring and management of the silver carp captive area.

[0019] The two enclosure nets are spaced 2 m apart, and the purpose is to conduct daily fish escape inspections in the water body between the two enclosure nets. If silver carp are found in this area, it is necessary to check whether there are holes in the enclosure net and make up for the leaks.

[0020] Furthermore, the method also includes the steps of fish monitoring and supplementation. The fish detection includes catching silver carp over 5 kg and at the same time supplementing and stocking silver carp. The fish detection and supplementation ensure that there are enough fish in the area to reduce the algal biomass.

[0021] Compared with the prior art, the present invention discloses a method for promoting lake pollutant reduction, carbon fixation and carbon sink enhancement by combining the construction of the bottom trough of the lakeside wetland water to the outer edge water area and silver carp algae control, and has the following advantages and beneficial effects:

[0022] According to the law of sweeping lake bottom pollutants by wind waves and flow disturbance in the lakeside zone, as well as the sedimentation characteristics of organic debris and particulate matter, the present invention excavates deep trenches near lakeside wetlands with more organic debris to capture and bury pollutants and increase the carbon sink function of the lake; at the same time, the water purification and carbon fixation capabilities of wetland plants are utilized, combined with the algae control and carbon fixation capabilities of silver carp, to innovate and integrate the pollution reduction, carbon fixation and carbon sink enhancement technical methods of lakes, effectively improving the pollution reduction and carbon sink capabilities of lakes. If the bottom trough, fish control area and lakeside wetland plants are not scientifically and effectively combined in the lakeside wetland system, the pollution reduction and carbon sink effect of the lakeside wetland will be greatly reduced. This method meets the technical requirements of pollution reduction, carbon fixation and carbon sink enhancement, has a low economic cost, is simple and easy to operate, is effective for a long time after technical implementation, and can be promoted on a large scale. It is not only suitable for pollution reduction and carbon fixation in lake wetlands, but also can reduce blue algae blooms in lakeside waters, providing technical support for the restoration of medium and large lake wetlands and the improvement of carbon sink functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solution in the present invention, the drawings required for use in the prior art description will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0024] Figure 1 It is a schematic cross-sectional structure diagram of the implementation site of the technology of the present invention.

[0025] Figure 2 It is a schematic diagram of the top view of the structure of the implementation site of the technology of the present invention.

[0026] Figure 3 These are the field test results of fish algae control using the technology of the present invention.

[0027] In the picture: 1 is the lakeshore; 2 is wetland plants, including reeds, cattails, etc.; 3 is the trough dug at the bottom of the lake; 4 is the seine net; 5 is silver carp; 6 is the lake bottom. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example 1

[0030] Implementation of site selection:

[0031] Choose the Paihekou Wetland in Chaohu as the implementation plot. The organic carbon content in the sediment of 0-10 cm in this wetland area is 6.0-13.5 gC / kg, the total nitrogen content is 1.50%-2.56 g / kg, and the total phosphorus content is 0.96-1.28 g / kg; the plant community takes reed as the dominant species, the average community height is 240 cm, the vegetation coverage is 90%-100%, and the above-ground biomass is on average 2285 g / m 2 As Figure 1 and Figure 2 shown, use a mechanical dredger to excavate a deep trough at the bottom of the lake:

[0032] First, use a water-based mechanical excavator to select the location for excavating the bottom trough about 100 m from the outer edge of the water in the lakeside wetland, as Figure 1 and Figure 2 , excavate the deep trough at the bottom of the lake. The width of the bottom trough is appropriately 4 m, the depth is appropriately 4 m, and the length is 100 m.

[0033] Secondly, as Figure 1 and Figure 2 shown, construct a fish algae control and carbon sink increase area:

[0034] In the Paihekou Wetland in Chaohu, lay two enclosures from the lakeshore to about 120 m from the outer edge of the water of the lakeside wetland plants, as Figure 1 and Figure 2 , the interval between the two enclosures is 2 m, parallel to the lakeshore line, and enclose a closed silver carp captive area with the lakeshore line. The area of the enclosure aquaculture area is 120 m×100 m; take Figure 2 a captive area of an enclosure shown in

[0035] as the on-site test demonstration and monitoring area. 2 Stock silver carp in the silver carp captive area, with a stocking density of 100 g / m

[0036] In the implementation process of the technology of the present invention, fish monitoring in the fish algae control and carbon sink increase area was carried out. According to the monitoring situation, silver carp were replenished and stocked in a timely manner to ensure that there were enough fish in the area to reduce the algal biomass.

[0037] In addition, carry out dredging and silt removal work on the deep trough every three years to further increase the pollution reduction, carbon fixation and carbon sink increase capacity of the system.

[0038] Implementation effect monitoring:

[0039] The thickness of the polluted sediment rich in nitrogen, phosphorus and organic carbon captured and deposited in the excavated bottom trough in the current year reached 1.43 m. Compared with the sediments around the bottom trough, the organic carbon content of the sediment deposited in the bottom trough was on average 43.2% higher, the total nitrogen content was on average 15.6% higher, and the total phosphorus content was on average 37.4% higher. The main reason is that a large amount of organic debris and silver carp feces in the wetland were disturbed by the wind and lake currents and carried into the bottom trough, indicating that the bottom trough has a strong ability to capture and bury nitrogen, phosphorus and organic matter, effectively improving the pollution reduction and carbon sequestration efficiency of the lake.

[0040] From May to October, the cyanobacterial bloom in the central water area of the silver carp captive area was reduced by 11.2 - 61.3%, with an average of 30.8%. The average weight gain of silver carp was 63.5%, indicating that fish in the area can effectively feed on cyanobacteria, control cyanobacterial blooms and convert algal carbon into fish bodies. Part of the feces excreted by fish is deposited in the wetland sediment to convert into fertilizer to promote the growth and absorption of wetland plants, and part is carried into the bottom trough to form buried nitrogen and phosphorus nutrients and carbon sinks. The average biomass of reeds in this area was 13.6% higher than that in the control area, indicating that the amount of carbon fixed by plants in the wetland increased significantly, and the carbon sequestration effect of the wetland was significantly enhanced.

[0041] Compared with the control area (lakeside wetland), in the technical demonstration area (lakeside wetland + bottom trough + silver carp algae control) of the embodiment of the present invention, the soil carbon storage in the sediment layer of 0 - 50 cm in the technical demonstration area in the second year was on average 56.4 tC / hm 2 , and the carbon sequestration rate was 15.9 tC / hm 2 / a, and the carbon sequestration rate increased by 76.2% compared with the control area.

[0042] A bottom trough not close to the wetland area was set up separately as a comparative test, that is, the bottom trough was used alone for carbon sequestration without combining with fish algae control. Compared with this comparative test, the carbon sequestration effect of this technology can be increased by up to 42%; compared with using fish algae control alone, the carbon sequestration efficiency of this technology was increased by 55%; compared with only using wetland carbon sequestration, the carbon sequestration efficiency of this technology was increased by 28%. It can be seen that the combined use of lakeside wetland + bottom trough + silver carp algae control can significantly enhance the carbon sequestration effect.

[0043] Example 2

[0044] This example is divided into two parts: experimental study on the capture of lake bottom trough pollutants and experimental study on the control of cyanobacterial blooms by silver carp and bighead carp.

[0045] Experimental Study on Pollutant Capture in Lake Bottom Troughs: Six experimental sites were selected in Chaohu Lake, distributed in different lake flow characteristic areas of the lakeshore zone, nearshore zone, and central lake area. A bottom trough was excavated at the lake bottom using a water excavator. The width of the bottom trough was 2 - 5 m, the depth was 2 - 4 m, and the length was 30 m. All the excavated bottom troughs were parallel to the lake shoreline, with offshore distances of 50 m, 100 m, 120 m, and 500 m. The research results show that the bottom trough can sweep the floating sludge on the lake bottom within 120 m on both sides into the trough at most. If the bottom trough is too close to the wetland, it will limit the expansion of wetland plants towards the center of the lake. If the bottom trough is too far from the wetland, the effect of capturing particulate pollutants will be poor. Therefore, it is recommended to set the bottom trough within the range of 50 - 100 m from the outer edge of the lakeshore wetland. According to the deposition rate and resuspension characteristics of pollutants such as floating sludge in the bottom trough, the preferred depth of the bottom trough is 2 - 4 m, and the preferred width is 3 - 5 m. The siltation thickness can exceed the relatively static water layer in the lower part of the bottom trough and reach the upper disturbed water layer in about 3 years. It is recommended to carry out dredging once every about 3 years. Third-party monitoring conducted on-site sampling of sediments at different depth layers (stratified at intervals of 5 cm from 0 - 20 cm) in the bottom trough (PC1, PC4), the water area affected by the bottom trough (PC2, PC5), and the open water area outside the bottom trough (PC3, PC6) from March to June 2021. In the laboratory, the total nitrogen, total phosphorus, and loss on ignition (representing organic matter content) in the sediments were analyzed. The evaluation results show that the bottom trough can effectively reduce the total nitrogen, total phosphorus, and organic matter content in the sediments of the "affected water area". Among them, the reduction rates of total nitrogen and total phosphorus in the surface bottom mud of the lake bottom can reach 46% and 44% respectively, and the average reduction rate of organic matter is 63%. Specific monitoring data were selected from March to June, Tables 1 - 3. It can be seen that a large amount of organic matter is carried into the bottom trough by wind waves and lake currents, becoming a buried carbon pool.

[0046] Table 1 Statistical Table of Soil Test Results (March)

[0047]

[0048]

[0049] Table 2 Statistical Table of Soil Test Results (April)

[0050]

[0051]

[0052] Table 3 Statistical Table of Soil Test Results (May)

[0053]

[0054]

[0055] Experimental Study on Controlling Cyanobacterial Bloom by Silver Carp and Bighead Carp: From April to December 2020, six 25m×25m experimental enclosures were constructed on-site in the waters of Chaohu Lake to carry out the experiment on controlling algae by silver carp and bighead carp. The results showed that under the condition of water depth of 2.20 - 2.85m, 50 - 150g / m of silver carp and bighead carp were stocked 2 , and the algae control effect was better, and the control benefit was higher when the stocking size was 0.3 - 0.5kg per fish. At the same time, the effect of silver carp on controlling cyanobacterial bloom was 12 - 30% higher than that of bighead carp. Therefore, silver carp is preferred when implementing this technology. The experimental data are shown in Figure 3 .

[0056] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for constructing a bottom trough in combination with silver carp to promote pollution reduction, carbon fixation and carbon sink increase in lakes, characterized in that It includes the following steps: (1) Build a bottom trough downward on the lake bottom within a range of 50 - 100 m from the water of the lakeside wetland in a medium - large lake to the outer - edge water area, and the bottom trough is parallel to the lake shoreline; (2) Form one or more enclosed silver carp captive - breeding areas by deploying enclosures from the lake shoreline to 120 m from the water of the lakeside wetland to the outer - edge water area, and then stock silver carp in the silver carp captive - breeding areas.

2. The method according to claim 1, wherein In step (1), the width of the bottom trough is 3 - 5 m and the depth is 2 - 4 m.

3. The method according to claim 1, characterized in that In step (1), the length of the bottom trough is the same as or slightly less than the length of the lakeside wetland.

4. The method according to claim 1, wherein Step (1) also includes the step of regularly dredging and cleaning the bottom trough; more preferably, the dredging and cleaning is carried out once every 3 years.

5. The method according to claim 1, characterized in that, In step (2), there are two enclosures, and the distance between the two enclosures is 2 m.

6. The method according to claim 1, characterized in that In step (2), the length of the silver carp captive - breeding area is 100 - 1000 m.

7. The method according to claim 1, characterized in that The stocking density of the silver carp is 50g~150g / m 2 , and the silver carp is 0.3~0.5 kg per fish.

8. The method according to claim 1, wherein In step (2), there are multiple silver carp captive - breeding areas, and the total length of all the areas where the silver carp captive - breeding areas are located along the lake shoreline is equal to or slightly less than the length of the wetland, and there are intervals between adjacent silver carp captive - breeding areas.

9. The method according to claim 1, characterized in that, The method also includes the steps of fish monitoring and replenishment. The fish detection includes catching silver carp over 5 kg and simultaneously replenishing and stocking silver carp.

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