A device and method for monitoring greenhouse gas emission fluxes at the water-atmosphere interface of a drainage system

Abstract

The present application belongs to the technical field of greenhouse gas monitoring, in particular to a drainage system water-gas interface greenhouse gas emission flux monitoring device and method, which comprises a test system, a floating system and a traction system; the test system is composed of a static chamber, a temperature sensor, a pressure sensor, a micro fan, a lifting grommet, a gas sampling nozzle, a gas pipe, a vacuum pump and an aluminum foil sampling bag; the floating system is composed of a square foam base and a hollow metal pipe; the static chamber configuration is suitable for different monitoring scenes of the drainage system, breaks through the limitation of the installation and measurement of the water surface static chamber of the drainage pipe network at a certain depth, realizes the gas collection of the water surface of the pipe network at different depths, the present application integrates a double traction system, can arbitrarily switch the low water level and high water level traction systems according to the monitoring needs, realizes the effective fixation of the water surface static chamber, is suitable for the measurement of the greenhouse gas emission flux of the water-gas interface of the drainage system in multiple scenes, and is less affected by the environmental uncertainty of the drainage system.

Description

Technical Field

[0001] This invention belongs to the field of greenhouse gas monitoring technology, specifically a device and method for monitoring greenhouse gas emission fluxes at the water-air interface of a drainage system. Background Technology

[0002] Global warming is a major challenge to human survival and development, and reducing greenhouse gas emissions is a key factor in controlling the greenhouse effect. Currently, the main greenhouse gases of concern include carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), with CO2 having the largest emission volume. Meanwhile, CH4 and N2O have global warming potentials that are 28 times and 265 times greater than CO2, respectively, making them the second largest contributors to global warming after CO2. Carbon emissions from drainage systems constitute a significant portion of total societal carbon emissions. Monitoring and calculating greenhouse gas emissions from drainage systems is crucial and contributes to promoting carbon reduction in these systems.

[0003] However, the aforementioned technologies often have the following drawbacks: Currently, the monitoring and accounting of greenhouse gases in drainage systems (including drainage pipe networks and sewage treatment plants) is mainly concentrated in sewage treatment plants, lacking monitoring and accounting of greenhouse gases in drainage pipe networks. Furthermore, the devices used in sewage treatment plants are not suitable for monitoring drainage pipe networks. Therefore, there is an urgent need to develop corresponding monitoring devices to achieve monitoring of greenhouse gas emission fluxes at the water-air interface in multiple scenarios within drainage systems. Currently, the method for measuring greenhouse gas emissions at the water-air interface typically uses the static chamber method, but the existing static chamber method also has a series of problems when used for monitoring greenhouse gas emissions at the water-air interface in drainage systems:

[0004] Existing static boxes are mainly used in surface water bodies (such as oceans, lakes, rivers and reservoirs), where the water surface directly exchanges gases with the atmosphere. Static boxes are simple to operate and easy to deploy. However, because the water surface of the drainage pipe network in the drainage system has a certain depth and the gas phase space at the top of the pipe is relatively closed, static boxes cannot be directly placed and measured as in surface water bodies.

[0005] To maintain stability and reduce measurement errors, existing static test chambers typically employ a large-area floating plate base, resulting in a large chamber volume. However, the limited water surface area and unique pipe structure of drainage systems make conventional static test chamber configurations unsuitable for measuring greenhouse gas emissions from the water surface of drainage networks.

[0006] The overall flow velocity of water in drainage systems is relatively high, and the floating plate base is insufficient to provide corresponding stability for the static box. At the same time, the static box, which lacks a traction system, is easily washed away by the water flow in drainage systems, especially drainage pipe networks. Therefore, this invention provides a device and method for monitoring greenhouse gas emission flux at the water-air interface of drainage systems. Summary of the Invention

[0007] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.

[0008] The technical solution adopted by the present invention to solve its technical problem is as follows: The present invention provides a monitoring device for greenhouse gas emission flux at the water-air interface of a drainage system, comprising a test system, a floating system and a traction system; the test system consists of a static chamber, a temperature sensor, a pressure sensor, a micro fan, a lifting hook, a gas sampling nozzle, a gas pipe, a vacuum pump and an aluminum foil sampling bag; the floating system consists of a square foam base and a hollow metal tube.

[0009] Preferably, in the aforementioned test system, the static chamber is a cylindrical box with an open bottom; the temperature sensor, pressure sensor, and miniature fan are installed inside the static chamber, and the top of the static chamber is equipped with a lifting hook and a gas sampling nozzle; the gas sampling nozzle is connected to a vacuum pump and an aluminum foil gas sampling bag via a gas pipe.

[0010] Preferably, in the floating system, a square foam base is fitted to the bottom of the static chamber opening; the square foam base has openings at its four corners, and hollow metal tubes of corresponding length are installed inside the four corner openings and on the outer sides of the base opposite to the sides.

[0011] Preferably, the traction system consists of a telescopic rod, a lead weight, and a nylon rope, and the traction system further includes a low-water-level traction system and a high-water-level traction system.

[0012] Preferably, in the low-water-level traction system, the telescopic rod passes through the hollow metal tube on the outside of the base and extends to the bottom of the pipe to fix the static chamber; in the high-water-level traction system, the nylon rope passes through the hollow metal tubes at the four corners of the base and is connected to the lead weight, which sinks to the bottom, and the static chamber is fixed by the tension on the nylon rope.

[0013] Preferably, the top surface of the square foam base is provided with a flow guide groove, the bottom surface of the square foam base is provided with a set of flow guide holes communicating with the flow guide groove, and a stabilizing block is fixedly connected to the bottom surface of the square foam base. The top of the stabilizing block is open, and the port of the stabilizing block is connected with the flow guide hole.

[0014] Preferably, a pair of symmetrically arranged water inlet pipes are fixedly connected to the side wall of the stabilizing block, a sealing plate is provided on the side wall of the stabilizing block to seal the water inlet pipes, and a moving component for driving the sealing plate to move is provided on the bottom surface of the square foam base.

[0015] Preferably, the movable component includes a set of connecting rods fixedly connected to the bottom surface of the square foam base, a slide rod slidably connected to the bottom end of the connecting rod, a first spring fixedly connected between the top end of the slide rod and the inner wall of the connecting rod, a sealing plate fixedly connected to the bottom end of the slide rod, and a float fixedly connected to the surface of the slide rod.

[0016] Preferably, a fixing block is fixedly connected to the bottom surface of the square foam base, a sliding groove is provided in the fixing block, a sensor sheet is fixedly connected to the inner wall of the center part of the sliding groove, and a sensor ball is movably connected in the sliding groove.

[0017] Preferably, a connecting block is fixedly connected to the bottom surface of the fixed block, a moving groove is provided at the top of the connecting block, the sensing ball is disposed in the moving groove, a driving component for driving the sensing ball to move is provided in the moving groove, and a circular hole communicating with the moving groove is provided on the inner wall of the sliding groove.

[0018] Preferably, the drive assembly includes a hollow elastic ring fixed to the side wall of the connecting rod. When the float rises under the action of buoyancy, it can squeeze the elastic ring. A connecting pipe connects the elastic ring and the moving groove. A piston is slidably and sealingly connected to the inner wall of the moving groove. A round rod is slidably and sealingly connected to the bottom surface of the connecting block. The top surface of the round rod is fixedly connected to the piston. A second spring is fixedly connected between the bottom surface of the piston and the inner wall of the moving groove.

[0019] A method for monitoring greenhouse gas emission fluxes at the water-air interface of a drainage system, the method employing the aforementioned monitoring device for greenhouse gas emission fluxes at the water-air interface of a drainage system, the method comprising the following steps:

[0020] S1: Select the low water level traction system and the high water level traction system according to the water level of the measurement point. The head of the telescopic rod of the low water level traction system always passes through the hollow metal tube on the outside of the base. The nylon rope of the high water level traction system passes through the hollow metal tubes at the four corners of the base and is connected to the lead fish.

[0021] S2: Turn on the miniature fan and control the vacuum pump to run. Use the lifting hook to slowly lower the device to ensure that the ambient gas above the water surface in the static chamber is fully mixed. After the device is lowered to the water surface, the vacuum pump stops running. Keep the traction system telescopic rod and the lead weight always acting on the bottom of the contact surface.

[0022] S3: After the device stabilizes, start timing and sampling. Connect the aluminum foil gas sampling bag to the gas sampling nozzle through the gas tube. Control the vacuum pump to extract 10-20 mL of gas sample every 5 minutes, and extract the gas sample 4-6 times in total. At the same time, record the real-time gas pressure and temperature according to the pressure sensor and temperature sensor.

[0023] S4: After sampling, the gas sample is quantitatively analyzed by gas chromatography to obtain the concentration of greenhouse gases in the sample. Based on the obtained greenhouse gas concentration, time, temperature and pressure, the greenhouse gas emission flux at the water-air interface is calculated.

[0024] The beneficial effects of this invention are as follows:

[0025] 1. The static box configuration of this invention is applicable to different monitoring scenarios in drainage systems, breaking through the limitations of static box installation and measurement at a certain depth in drainage pipe network water surface, and realizing gas collection at different depths of pipe network water surface. This invention integrates a dual traction system, which can arbitrarily switch between low water level and high water level traction systems according to monitoring needs, realizing effective fixation of the static box on the water surface. It is suitable for measuring greenhouse gas emission flux at the water-air interface in multiple scenarios of drainage systems, and is less affected by the uncertainty of the drainage system environment.

[0026] 2. The monitoring device of the present invention is easy to carry, and the components such as sensors and telescopic rods are easy to replace. The device has a simple measurement method, a reasonable process, and strong operability. It does not require professional operators. The monitoring device adopts an integrated design, with a simple and compact structure, low cost, and is easy to manufacture into modular equipment with wide applicability. Attached Figure Description

[0027] The invention will now be further described with reference to the accompanying drawings.

[0028] Figure 1 This is a schematic diagram of the greenhouse gas emission flux monitoring device in this invention;

[0029] Figure 2 This is a schematic diagram of the structure of the low-water-level traction system used in this invention;

[0030] Figure 3 This is a schematic diagram of the structure of the high-water-level traction system used in this invention;

[0031] Figure 4 This is a schematic diagram of the static chamber, the square foam base, and the stabilizing block in this invention;

[0032] Figure 5 yes Figure 4 A bottom view;

[0033] Figure 6 This is a schematic diagram of the internal structure of the square foam base and the stabilizing block in this invention;

[0034] Figure 7 yes Figure 6 Enlarged view of point A;

[0035] Figure 8 This is a flowchart of the method in this invention.

[0036] In the diagram: 1. Static chamber; 2. Temperature sensor; 3. Pressure sensor; 4. Miniature fan; 5. Lifting hook; 6. Gas sampling nozzle; 7. Gas tube; 8. Vacuum pump; 9. Aluminum foil sampling bag; 10. Square foam base; 11. Hollow metal tube; 12. Telescopic rod; 13. Lead weight; 14. Nylon rope; 15. Flow guide channel; 16. Flow guide hole; 17. Stabilizing block; 18. Water inlet pipe; 19. Connecting rod; 20. Sliding rod; 21. Sealing plate; 22. Float; 23. Elastic ring; 24. Connecting pipe; 25. Fixing block; 26. Slide groove; 27. Induction ball; 28. Induction plate; 29. ​​Connecting block; 30. Moving groove; 31. Piston; 32. Round rod. Detailed Implementation

[0037] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0038] Example 1: As Figures 1 to 3 As shown in the embodiment of the present invention, a greenhouse gas emission flux monitoring device for the water-air interface of a drainage system includes a test system, a floating system, and a traction system. The test system consists of a static chamber 1, a temperature sensor 2, a pressure sensor 3, a miniature fan 4, a lifting hook 5, a gas sampling nozzle 6, a gas pipe 7, a vacuum pump 8, and an aluminum foil sampling bag 9. The floating system consists of a square foam base 10 and a hollow metal tube 11.

[0039] In the aforementioned test system, the static chamber 1 is a cylindrical box with an open bottom; the temperature sensor 2, pressure sensor 3, and miniature fan 4 are installed inside the static chamber 1, and the top of the static chamber 1 is equipped with a lifting hook ring 5 and a gas sampling nozzle 6; the gas sampling nozzle 6 is connected to a vacuum pump 8 and an aluminum foil gas sampling bag through a gas pipe 7.

[0040] In the aforementioned floating system, a square foam base 10 is fitted to the bottom of the open static chamber 1; the square foam base 10 has openings at its four corners, and hollow metal tubes 11 of corresponding length are installed inside the four corner openings and on the outer side of the opposite side of the base.

[0041] The traction system consists of a telescopic rod 12, a lead weight 13, and a nylon rope 14. The traction system also includes a low-water-level traction system and a high-water-level traction system.

[0042] In the low-water-level traction system, the telescopic rod 12 passes through the hollow metal tube 11 on the outside of the base and extends to the bottom of the pipe to fix the static chamber 1; in the high-water-level traction system, the nylon rope 14 passes through the hollow metal tubes 11 at the four corners of the base and is connected to the lead weight 13. The lead weight 13 sinks to the bottom and is fixed to the static chamber 1 by the tension on the nylon rope 14.

[0043] This invention allows for the selection of either a low-water-level traction system or a high-water-level traction system based on the water level at the measurement site. In the low-water-level traction system, the head of the telescopic rod 12 always passes through the hollow metal tube 11 on the outside of the base. In the high-water-level traction system, the nylon rope 14 passes through the hollow metal tubes 11 at the four corners of the base and connects to the lead weight 13. Then, the micro fan 4 is turned on, and the vacuum pump 8 is controlled to operate. The device is slowly lowered using the lifting hook 5 to ensure thorough mixing of the ambient gas above the water surface in the static chamber 1. After the device is lowered to the water surface, the vacuum pump 8 stops operating, maintaining the telescopic rod 12 or lead weight 13 at the bottom of the contact surface. Once the device is stable, timing and sampling begin. The aluminum foil gas sampling bag is connected to the gas sampling nozzle 6 via the gas tube 7. Every 5 minutes, the vacuum pump 8 extracts 10-20 mL of gas sample, for a total of 5 extractions. Simultaneously, the real-time gas pressure and temperature are recorded using the pressure sensor and temperature sensor 2. After sampling, the gas sample is quantitatively analyzed using a gas chromatograph to obtain the concentration of greenhouse gases in the sample. Calculate the greenhouse gas emission flux at the water-air interface based on the obtained greenhouse gas concentration, time, temperature, and pressure.

[0044] The static box configuration of this invention is applicable to different monitoring scenarios in drainage systems, breaking through the limitations of static box installation and measurement at a certain depth in drainage pipe networks, and realizing gas collection at different depths of pipe network water surfaces. This invention integrates a dual traction system, which can switch between low water level and high water level traction systems as needed for monitoring, achieving effective fixation of the static box on the water surface. It is suitable for measuring greenhouse gas emission fluxes at the water-air interface in multiple scenarios of drainage systems, and is less affected by the uncertainty of the drainage system environment. The monitoring device of this invention is easy to carry, and the components such as sensors and telescopic rods 12 are easy to replace. The device measurement method is simple, the process is reasonable, and it is highly operable, requiring no professional operators. It adopts an integrated design, with a simple and compact structure, low cost, and is easy to manufacture into modular equipment, making it widely applicable.

[0045] Example 2: Figures 4 to 7 As shown in the comparative embodiment one, another embodiment of the present invention is as follows: the top surface of the square foam base 10 is provided with a flow guide groove 15, the bottom surface of the square foam base 10 is provided with a set of flow guide holes 16 communicating with the flow guide groove 15, and a stabilizing block 17 is fixedly connected to the bottom surface of the square foam base 10. The top end of the stabilizing block 17 is open, and the port of the stabilizing block 17 is connected with the flow guide hole 16.

[0046] When the square foam base 10 in this application comes into contact with the water surface, timing and sampling can begin after the device has stabilized. At this time, the center of gravity of the square foam base 10 can be lowered by using the stabilizing block 17 set on the square foam base 10, thereby enhancing stability. At the same time, due to the water flow, if the water flow is large, the water flow will impact the top of the square foam base 10 and accumulate on the top of the square foam base 10, thus affecting the stability of the device. At this time, the guide channel 15 can be used to guide the water impacting the square foam base 10, so that the water enters the guide channel 15 and then flows into the stabilizing block 17 from the guide hole 16, so that there is no water accumulation on the top of the square foam base 10, thereby improving the stability of the square foam base 10 during use. At the same time, the water entering the stabilizing block 17 will increase the weight of the stabilizing block 17, thereby further improving the stability provided by the stabilizing block 17 to the square foam base 10.

[0047] The side wall of the stabilizing block 17 is fixedly connected to a pair of symmetrically arranged water inlet pipes 18. The side wall of the stabilizing block 17 is provided with a sealing plate 21 to seal the water inlet pipes 18. The bottom surface of the square foam base 10 is provided with a moving component to drive the sealing plate 21 to move. When the square foam base 10 comes into contact with the water surface, the water will submerge the water inlet pipes 18, causing water to enter the stabilizing block 17, thereby increasing the weight of the stabilizing block 17 and improving the stabilizing effect on the square foam base 10. After the water level in the stabilizing block 17 reaches a certain level, some space needs to be reserved for the water on the square foam base 10 to be discharged. At this time, the sealing plate 21 can be controlled to rise by the moving component to seal the water inlet pipes 18.

[0048] The moving component includes a set of connecting rods 19 fixedly connected to the bottom surface of the square foam base 10. A slide rod 20 is slidably connected to the bottom end of the connecting rod 19. A first spring is fixedly connected between the top end of the slide rod 20 and the inner wall of the connecting rod 19. The sealing plate 21 is fixedly connected to the bottom end of the slide rod 20. A float 22 is fixedly connected to the surface of the slide rod 20. When the stabilizing block 17 enters the water, water will enter the stabilizing block 17 from the water inlet pipe 18. After the float 22 enters the water, the float 22 will drive the slide rod 20 to move upward. At this time, the slide rod 20 will drive the sealing plate 21 to move upward to seal the water inlet pipe 18. When the device is removed from the water, the sealing plate 21 will slide downward due to gravity, so that the sealing plate 21 no longer seals the water inlet pipe 18. At this time, the water in the stabilizing block 17 can be discharged from the water inlet pipe 18.

[0049] A fixing block 25 is fixedly connected to the bottom surface of the square foam base 10. A groove 26 is provided in the fixing block 25. A sensing plate 28 is fixedly connected to the inner wall of the center part of the groove 26. A sensing ball 27 is movably connected in the groove 26. When the square foam base 10 in this application is placed in water, it will shake and become unstable. The test system needs to be stabilized before it can work. However, whether the square foam base 10 is stable in water can be observed by hand and there will be a deviation. With the above mechanism, when the square foam base 10 is stable, the sensing ball 27 will be centered in the groove 26. At this time, after the sensor contacts the sensing plate 28 for more than four seconds, the test system will be automatically started to work, so as to improve the accuracy of the experimental data.

[0050] The bottom surface of the fixed block 25 is fixedly connected to the connecting block 29, and the top of the connecting block 29 is provided with a moving groove 30. The sensing ball 27 is disposed in the moving groove 30, and a driving component for moving the sensing ball 27 is provided in the moving groove 30. The inner wall of the sliding groove 26 is provided with a circular hole communicating with the moving groove 30. In this application, during the movement of the device, the sensing ball 27 may accidentally stop at the sensing plate 28, which may cause the experimental system to start erroneously. The above mechanism can store the sensing ball 27 in the moving groove 30 to prevent accidental triggering of the experimental system. Then, when the moving ball needs to be used, the driving component can be used to drive the sensing ball 27 from the moving groove 30 into the sliding groove 26.

[0051] The drive assembly includes a hollow elastic ring 23 fixed to the side wall of the connecting rod 19. When the float 22 rises under buoyancy, it can compress the elastic ring 23. A connecting pipe 24 connects the elastic ring 23 and the moving groove 30. A piston 31 is slidably and sealingly connected to the inner wall of the moving groove 30. A round rod 32 is slidably and sealingly connected to the bottom surface of the connecting block 29. The top surface of the round rod 32 is fixedly connected to the piston 31. A second spring is fixedly connected between the bottom surface of the piston 31 and the inner wall of the moving groove 30. The stabilizing block 17 in this application, after entering the water... The float 22 will move upward due to buoyancy. At this time, the float 22 will squeeze the elastic ring 23, so that the gas in the elastic ring 23 will enter the moving groove 30 through the connecting pipe 24. The gas will push the piston 31 to rise, so that the piston 31 moves to be flush with the top end of the round hole. At this time, the sensing ball 27 will enter the sliding groove 26. After the device is removed from the water surface, the float 22 will move downward. At this time, the piston 31 will be reset under the pull of the second spring. Then, the device can be placed horizontally on the ground to allow the sensing ball 27 to enter the moving groove 30 through the round hole.

[0052] like Figure 8As shown, a method for monitoring greenhouse gas emission fluxes at the water-air interface of a drainage system is disclosed. This method employs the aforementioned monitoring device for greenhouse gas emission fluxes at the water-air interface of a drainage system and includes the following steps:

[0053] S1: Select a low-water-level traction system and a high-water-level traction system according to the water level at the measurement point. The head of the telescopic rod 12 of the low-water-level traction system always passes through the hollow metal tube 11 on the outside of the base. The nylon rope 14 of the high-water-level traction system passes through the hollow metal tubes 11 at the four corners of the base and is connected to the lead weight 13.

[0054] S2: Turn on the miniature fan 4, control the vacuum pump 8 to run, and slowly lower the device through the lifting hook ring 5 to ensure that the ambient gas above the water surface in the static chamber 1 is fully mixed. After the device is lowered to the water surface, the vacuum pump 8 stops running, and the traction system telescopic rod 12 and lead weight 13 are always acting on the bottom of the contact surface.

[0055] S3: After the device stabilizes, start timing and sampling. Connect the aluminum foil gas sampling bag to the gas sampling nozzle 6 through the gas tube 7. Control the vacuum pump 8 to extract 10-20 mL of gas sample every 5 minutes. Extract gas sample 4-6 times in total. At the same time, record the real-time gas pressure and temperature according to the pressure sensor and temperature sensor 2.

[0056] S4: After sampling, the gas sample is quantitatively analyzed using a gas chromatograph to obtain the concentration of greenhouse gases in the sample. Based on the obtained greenhouse gas concentrations, time, temperature, and pressure, the greenhouse gas emission flux at the water-air interface is calculated using the following formula:

[0057] F=(V / A)×(P / P0)×(T0 / T)×(dc / dt)

[0058] Where: F: Gas flux at the water-air interface measured in the static chamber (g·m³) -2 ·h -1 );

[0059] V: Static chamber gas volume (m³) 3 );

[0060] A: Static box bottom coverage area (m²) 2 );

[0061] P: Air pressure at the sampling point (hpa);

[0062] P0: Air pressure under standard conditions (1013.25 hPa);

[0063] T0: Temperature under standard conditions (273.15K)

[0064] T: Air temperature inside the static chamber (K);

[0065] dc / dt: Rate of change of greenhouse gas concentration in a static chamber (g·m³) -3 ·h -1 ).

[0066] The greenhouse gas (CH4 and N2O) emission fluxes at five different pipe types in a city's drainage network in the Yangtze River Delta region were determined using the monitoring device and measurement method described above.

[0067] Working principle: The system can be configured with either a low-water-level or high-water-level traction system based on the water level at the measurement site. In the low-water-level traction system, the head of the telescopic rod 12 always passes through the hollow metal tube 11 on the outside of the base. In the high-water-level traction system, the nylon rope 14 passes through the hollow metal tubes 11 at the four corners of the base and connects to the lead weight 13. Then, the micro fan 4 is turned on, controlling the vacuum pump 8 to operate. The device is slowly lowered using the lifting hook 5 to ensure thorough mixing of the ambient gas above the water surface in the static chamber 1. After the device reaches the water surface, the vacuum pump 8 stops operating, maintaining the telescopic rod 12 or lead weight 13 at the bottom of the contact surface. Once the device is stable, timing and sampling begin. The aluminum foil gas sampling bag is connected to the gas sampling nozzle 6 via the gas tube 7. Every 5 minutes, the vacuum pump 8 extracts 10-20 mL of gas sample, for a total of 5 extractions. Simultaneously, the real-time gas pressure and temperature are recorded using the pressure sensor and temperature sensor 2. After sampling, the gas sample is quantitatively analyzed using a gas chromatograph to obtain the concentration of greenhouse gases in the sample. Calculate the greenhouse gas emission flux at the water-air interface based on the obtained greenhouse gas concentration, time, temperature, and pressure.

[0068] The static box configuration of this invention is applicable to different monitoring scenarios in drainage systems, breaking through the limitations of static box installation and measurement at a certain depth in drainage pipe networks, and realizing gas collection at different depths of pipe network water surfaces. This invention integrates a dual traction system, which can switch between low water level and high water level traction systems as needed for monitoring, effectively fixing the static box on the water surface. It is suitable for measuring greenhouse gas emission fluxes at the water-air interface in multiple scenarios of drainage systems, and is less affected by the uncertainty of the drainage system environment. The monitoring device of this invention is easy to carry, and the components such as sensors and telescopic rods 12 are easy to replace. The device measurement method is simple, the process is reasonable, and it is highly operable, requiring no professional operators. It adopts an integrated design, with a simple and compact structure, low cost, easy to manufacture modular equipment, and wide applicability.

[0069] When the square foam base 10 comes into contact with the water surface, timing and sampling should begin only after the device has stabilized. At this time, the center of gravity of the square foam base 10 can be lowered by using the stabilizing block 17, which enhances stability. However, due to water flow, if the flow is large, the water will impact the top of the square foam base 10, causing water to accumulate on its surface and affecting the device's stability. The guide channel 15 can then guide the water impacting the square foam base 10, allowing it to flow into the guide channel 15 and then into the stabilizing block 17 through the guide hole 16. This prevents water accumulation on the top of the square foam base 10, improving its stability during use. The water entering the stabilizing block 17 also increases its weight, further enhancing the stability provided by the stabilizing block 17 to the square foam base 10. When the base 10 comes into contact with the water surface, the water will submerge the inlet pipe 18, causing water to enter the stabilizing block 17, thereby increasing the weight of the stabilizing block 17 and improving the stabilizing effect on the square foam base 10. After the water level in the stabilizing block 17 reaches a certain level, some space needs to be reserved for the water on the square foam base 10 to drain. At this time, the sealing plate 21 can be controlled by the moving component to rise and seal the inlet pipe 18. When the stabilizing block 17 enters the water, water will enter the stabilizing block 17 from the inlet pipe 18. Then, after the float 22 enters the water, the float 22 will drive the slide rod 20 to move upward. At this time, the slide rod 20 will drive the sealing plate 21 to move upward to seal the inlet pipe 18. When the device is removed from the water, the sealing plate 21 will slide downward due to gravity, so that the sealing plate 21 no longer seals the inlet pipe 18. At this time, the water in the stabilizing block 17 can be discharged from the inlet pipe 18.

[0070] The terms "front," "back," "left," "right," "top," and "bottom" all refer to the figures in the accompanying drawings. Figure 1 Based on the perspective of the observer, the side of the device facing the observer is defined as the front, the left side of the observer is defined as the left, and so on.

[0071] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0072] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A device for monitoring greenhouse gas emission fluxes at the water-air interface of a drainage system, comprising an experimental system, a floating system, and a traction system; Its features are: The test system consists of a static chamber (1), a temperature sensor (2), a pressure sensor (3), a miniature fan (4), a lifting hook (5), a gas sampling nozzle (6), a gas tube (7), a vacuum pump (8), and an aluminum foil sampling bag (9); The floating system consists of a square foam base (10) and a hollow metal tube (11), and the traction system is used to effectively fix the static chamber (1) on the water surface; The top surface of the square foam base (10) is provided with a flow channel (15), the bottom surface of the square foam base (10) is provided with a set of flow holes (16) communicating with the flow channel (15), and a stabilizing block (17) is fixedly connected to the bottom surface of the square foam base (10). The top of the stabilizing block (17) is open, and the port of the stabilizing block (17) is connected with the flow hole (16). The side wall of the stabilizing block (17) is fixedly connected to a pair of symmetrically arranged water inlet pipes (18), and the side wall of the stabilizing block (17) is provided with a sealing plate (21) to seal the water inlet pipes (18). The bottom surface of the square foam base (10) is provided with a moving component to drive the sealing plate (21) to move. The static chamber (1) in the test system is a cylindrical box with an open bottom. The temperature sensor (2), pressure sensor (3) and micro fan (4) are installed in the static chamber (1). The top of the static chamber (1) is provided with a lifting hook (5) and a gas sampling nozzle (6). The gas sampling nozzle (6) is connected to the vacuum pump (8) and aluminum foil sampling bag (9) through a gas pipe (7). In the floating system, the square foam base (10) is fitted to the open bottom of the static chamber (1). The square foam base (10) has openings at the four corners, and hollow metal tubes (11) of corresponding length are installed in the openings at the four corners and on the outer side of the base. The traction system consists of a telescopic rod (12), a lead weight (13), and a nylon rope (14). The traction system also includes a low-water-level traction system and a high-water-level traction system. In the low water level traction system, the telescopic rod (12) passes through the hollow metal tube (11) on the outside of the base and extends to the bottom of the pipe to fix the static chamber (1). In the high water level traction system, the nylon rope (14) passes through the hollow metal tube (11) at the four corners of the base and is connected to the lead weight (13). The lead weight (13) sinks to the bottom and is fixed to the static chamber (1) by the pull force of the nylon rope (14). The moving component includes a set of connecting rods (19) fixedly connected to the bottom surface of a square foam base (10). A slide rod (20) is slidably connected to the bottom end of the connecting rod (19). A first spring is fixedly connected between the top end of the slide rod (20) and the inner wall of the connecting rod (19). The sealing plate (21) is fixedly connected to the bottom end of the slide rod (20). A float (22) is fixedly connected to the surface of the slide rod (20).

2. The device for monitoring greenhouse gas emission flux at the water-air interface of a drainage system according to claim 1, characterized in that: The bottom surface of the square foam base (10) is fixedly connected to a fixing block (25), and a sliding groove (26) is provided in the fixing block (25). A sensor plate (28) is fixedly connected to the inner wall of the center part of the sliding groove (26), and a sensor ball (27) is movably connected in the sliding groove (26).

3. The device for monitoring greenhouse gas emission flux at the water-air interface of a drainage system according to claim 2, characterized in that: The bottom surface of the fixed block (25) is fixedly connected to the connecting block (29), and the top of the connecting block (29) is provided with a moving groove (30). The sensing ball (27) is disposed in the moving groove (30), and the moving groove (30) is provided with a driving component for driving the sensing ball (27) to move. The inner wall of the sliding groove (26) is provided with a round hole communicating with the moving groove (30).

4. The device for monitoring greenhouse gas emission flux at the water-air interface of a drainage system according to claim 3, characterized in that: The drive assembly includes a hollow elastic ring (23) fixed to the side wall of the connecting rod (19). When the float (22) rises under the action of buoyancy, it can squeeze the elastic ring (23). A connecting pipe (24) connects the elastic ring (23) and the moving groove (30). A piston (31) is slidably connected to the inner wall of the moving groove (30). A round rod (32) is slidably connected to the bottom surface of the connecting block (29). The top surface of the round rod (32) is fixedly connected to the piston (31). A second spring is fixedly connected between the bottom surface of the piston (31) and the inner wall of the moving groove (30).

5. A method for monitoring greenhouse gas emission fluxes at the water-air interface of a drainage system, the method employing the greenhouse gas emission flux monitoring device at the water-air interface of a drainage system as described in claim 4, characterized in that: The method includes the following steps: S1: Select the low water level traction system and the high water level traction system according to the water level of the measurement point. The head of the telescopic rod (12) of the low water level traction system always passes through the hollow metal tube (11) on the outside of the base. The nylon rope (14) of the high water level traction system passes through the hollow metal tube (11) at the four corners of the base and is connected to the lead fish (13). S2: Turn on the micro fan (4), control the vacuum pump (8) to run, and slowly lower the device through the lifting hook (5) to ensure that the ambient gas above the water surface in the static chamber (1) is fully mixed. After the device is lowered to the water surface, the vacuum pump (8) stops running, and the telescopic rod (12) and the lead weight (13) in the traction system always act on the bottom of the contact surface. S3: After the device stabilizes, start timing sampling. Connect the aluminum foil gas sampling bag to the gas sampling nozzle (6) through the gas tube (7). Control the vacuum pump (8) to extract 10-20 mL of gas sample every 5 minutes. Extract gas sample 4-6 times in total. At the same time, record the real-time gas pressure and temperature according to the pressure sensor and temperature sensor (2). S4: After sampling, the gas sample is quantitatively analyzed by gas chromatography to obtain the concentration of greenhouse gases in the sample. Based on the obtained greenhouse gas concentration, time, temperature and pressure, the greenhouse gas emission flux at the water-air interface is calculated.

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