Sediment-water interface greenhouse gas flux monitoring device and metering method

Abstract

The invention relates to the technical field of water body monitoring, and discloses a sediment-water interface greenhouse gas flux monitoring device and a metering method.The monitoring device comprises a gas-water monitoring box and three gas monitoring boxes which are installed on the same sliding rail through sliding connecting pieces, the gas-water monitoring box and the three gas monitoring boxes are hollow, the bottom surfaces of the gas-water monitoring box and the three gas monitoring boxes are movably connected with fixing plates, the gas-water monitoring box and the gas monitoring boxes are internally provided with filtering structures, the gas monitoring boxes are internally provided with exhaust structures, and the outer walls of the gas monitoring boxes are connected with gas sampling structures. The device can adapt to various water area environments, can realize in-situ continuous collection of the sediment-water interface greenhouse gas, and is high in practicability.

Description

Technical Field

[0001] The present invention relates to the technical field of water body monitoring, and in particular to a sediment-water interface greenhouse gas flux monitoring device and a metering method. Background Art

[0002] In recent years, with the increasing acceleration of industrialization, the impact of global warming caused by greenhouse gas emissions on human life has become increasingly significant, and people have become more and more concerned about the source and control of greenhouse gas emissions. As one of the main ecosystems on the earth, freshwater ecosystems are not only an important part of the global carbon and nitrogen cycle, but also an important natural source of global greenhouse gas emissions. The bottom sediments have a high content of organic matter and are rich in nitrogen nutrients. They are the main place for material and energy metabolism in aquatic ecosystems and an important source of greenhouse gas production in freshwater lakes. As a necessary link in greenhouse gas emissions from sediments, the sediment-water interface is crucial to accurately monitor the dynamic changes of its greenhouse gas flux to analyze the factors affecting greenhouse gas emissions.

[0003] Traditional methods for obtaining greenhouse gas fluxes at the sediment-water interface mainly include: (1) Boundary layer model method (diffusion model method). By measuring the gas concentration in the sediment pore water and the bottom water of the lake, the diffusion formula is used to calculate the flux. The disadvantages are: a. It is difficult to collect pore water; b. The operation of extracting water samples is complicated and there is sample contamination; c. Only the diffusion flux at the sediment-water interface can be obtained, and the flux discharged in the form of bubbles is ignored; d. The diffusion formula has many design parameters, and the selection of relevant parameters depends on the derivation of empirical formulas, which leads to large errors in the calculation results. (2) Indoor culture method. The disadvantages are: a. In the process of collecting sediment samples for indoor culture simulation, it is impossible to simulate the influence of physical and biological disturbances such as water level, wind speed, pressure and organisms in the natural state; b. The original physical, chemical and biological properties of the sediment may be destroyed during the sample collection process.

[0004] In general, the currently developed sediment-water interface greenhouse gas flux monitoring devices have the following problems, which in turn affect the accuracy of greenhouse gas flux monitoring: a. The interference of gas samples captured by the sampler during the sinking and rising of the sampling device on the actual collected sediment-water interface gas samples is ignored; b. The design of the device does not take into account the influence of hydrostatic pressure and the original gas in the air duct; c. Continuous sampling and observation are not possible.

[0005] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the application and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to ordinary technicians in the field. Summary of the invention

[0006] The purpose of the present invention is to provide a sediment-water interface greenhouse gas flux monitoring device and measurement method, which has accurate sampling, simple operation, can adapt to various water environments, can realize the in-situ continuous collection of greenhouse gases at the sediment-water interface, and has strong practicality.

[0007] In order to achieve the above objectives, this application is implemented by adopting the following technical solutions: In a first aspect, a sediment-water interface greenhouse gas flux monitoring device is provided, characterized in that it includes a gas-water monitoring box and a gas monitoring box; The gas-water monitoring box and the gas monitoring box are installed on the same slide rail through a sliding connector and controlled by a buckle. The gas-water monitoring box and the gas monitoring box are hollow and have a fixing device for fixing the gas-water monitoring box and the gas monitoring box connected to the bottom surface; The air-water monitoring box and the gas monitoring box are internally provided with a filtering structure for filtering the water and gas entering the air-water monitoring box and the gas monitoring box; the gas monitoring box is internally provided with an exhaust structure for discharging the gas entering the gas monitoring box; the outer wall of the gas monitoring box is connected to the gas collection structure; and a water outlet is provided on the side of the air-water monitoring box.

[0008] Optionally, the fixing device comprises a control structure and a movable fixing plate, and the fixing plate is adjustably connected to the gas monitoring box via the control structure.

[0009] Optionally, the control structure includes a spring buckle, a locking strip and a pull rope, the spring buckle is arranged in the middle of the fixing plate, the locking strip is arranged on the side of the fixing plate, and the spring buckle is connected to the pull rope.

[0010] Optionally, the filtering structure includes a filter membrane and a support plate, and two support plates are clamped on both sides of the filter membrane.

[0011] Optionally, the filter membrane includes a PTFE membrane and a one-way permeable geomembrane, the filter membrane in the gas monitoring box is a PTFE membrane, and the filter membrane in the gas-water monitoring box is a one-way permeable geomembrane.

[0012] Optionally, the exhaust structure includes a pull rod and a piston, the piston is installed inside the gas monitoring box, the piston is connected to the pull rod, and the pull rod passes through the gas monitoring box.

[0013] Optionally, the gas collection structure is an air bag, a gas collection hole is provided on the side wall of the gas monitoring box, and the air bag is connected to the gas monitoring box through the gas collection hole.

[0014] Optionally, an oil layer is applied to the connection of the fixed plate, an oil layer is applied to the holes on the side wall of the gas-water monitoring box through which the pull rod passes, and an oil layer is applied to the gas collection holes on the side wall of the gas monitoring box.

[0015] In the second aspect, a method for measuring greenhouse gas flux at the water body sediment-water interface is provided, which is achieved by a water body sediment-water interface greenhouse gas flux monitoring device. Adjust the length of the slide rail according to the water depth, and install the gas-water monitoring box and the three gas monitoring boxes on the slide rail by means of buckles; The entire device is slowly placed into the water, and when the device is close to the bottom of the water, the fixing device is manipulated to vertically insert into the sediment to fix the entire device; The gas sampling structure is used to collect atmospheric samples on the water surface at the site, wherein the greenhouse gas concentration is recorded as C0; When the bottom of the device coincides with the sediment-water interface, the gas and water collection begins, and the starting time T0 is recorded. The water gradually passes through the filter structure into the gas and water monitoring box, and the gas generated by the sediment in the area covered by the gas monitoring box passes through the filter structure and enters the three gas monitoring boxes respectively; After the collection period expires, the buckle is adjusted to enable the gas-water monitoring box and the gas monitoring box to slide up and down on the slide rail, and the rope connected to the gas-water monitoring box and the gas monitoring box is pulled to take out a single gas-water monitoring box or a single gas monitoring box; At the sampling time T 2-1 , T 2-2 and T 2-3 When the three gas monitoring boxes are taken out in sequence, the gas in the monitoring boxes is pushed into the gas collection structure through the exhaust structure; At the end of sampling T 2-3 The gas-water monitoring box is taken out simultaneously, and the water sample in the box is sent into the collection bottle by means of a pump to complete the entire sampling process.

[0016] The collected atmospheric samples C0 and the greenhouse gas concentrations C in the three gas monitoring boxes were measured using a laboratory gas chromatograph. 2-1 , C 2-2 and C 2-3 ; Calculate the greenhouse gas diffusion flux F at the sediment-water interface in the three gas monitoring boxes respectively 2-1 、F 2-2 and F 2-3 , the calculation formula is as follows: ; ; ; Where, V is the volume of a single gas monitoring box; A is the bottom area of ​​a single gas monitoring box; C 2-1 , C 2-2 and C2-3 are the gas concentration differences before and after sample collection in the three gas monitoring boxes, respectively, with the atmospheric concentration as the starting concentration C0; T 2-1 , T 2-2 and T 2-3 The time intervals for collecting samples for the three gas monitoring boxes.

[0017] Take F 2-1 、F 2-2 and F 2-3 The arithmetic mean of can be used as the average value of greenhouse gas diffusion flux F2 at the sediment-water interface at the monitoring point, and the formula is: ; The greenhouse gases in the water samples collected in the gas-water monitoring box were collected using the headspace balance method and their concentrations were determined using gas chromatography; ; ; In the formula, C w The concentration of dissolved gas in water sample; C1 is the gas concentration measured after headspace equilibrium; C0 is the atmospheric background concentration; V0 is the headspace air volume / L; V1 is the water sample volume used for headspace measurement / L; R is the universal gas constant; T is the water temperature / K; K0 is the gas solubility coefficient; A1, A2, and A3 are constants.

[0018] Calculate the total greenhouse gas flux F1 entering the gas-water monitoring box through diffusion and bubbling at the bottom of the gas-water monitoring box. The formula is: ;; Where, V is the volume of the gas-water monitoring box; A is the bottom area of ​​the gas-water monitoring box; C w It is the concentration of dissolved gas in water in the gas-water monitoring box sample; T 2-3 The time interval for collecting samples for the air and water monitoring box.

[0019] Calculate the average time-period bubbling flux F of greenhouse gases at the sediment-water interface at this point 2-1泡 、F 2-2泡 and F 2-3泡 and the total average bubbling flux F 1泡 , the formula is ; ; ; .

[0020] Compared with the prior art, the present invention has the following beneficial effects: By setting the length of the slide rail, accurate field in-situ collection of gas at the underwater sediment-water interface at any depth can be achieved; Gas samples can be collected in different time periods as needed, which is easy to operate and highly feasible, and can distinguish between gas diffusion flux and bubbling flux; When collecting gas samples, it is only necessary to adjust the exhaust structure so that all the collected gas can be sent into the air bag, which greatly improves the sampling accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 It is a plan view schematic diagram provided by an embodiment of a sediment-water interface greenhouse gas flux monitoring device and a measurement method of the present invention; Figure 2 It is a front view provided by an embodiment of a sediment-water interface greenhouse gas flux monitoring device and a measurement method of the present invention; Figure 3 It is a cross-sectional view provided by an embodiment of a sediment-water interface greenhouse gas flux monitoring device and a measurement method of the present invention; Figure 4 It is a schematic diagram of the structure of a gas monitoring box provided by an embodiment of a sediment-water interface greenhouse gas flux monitoring device and a measurement method of the present invention; Figure 5 It is a schematic diagram of the structure of a gas-water monitoring box provided by an embodiment of a sediment-water interface greenhouse gas flux monitoring device and a measurement method of the present invention; Figure 6 It is a top view of a fixing plate provided in an embodiment of a sediment-water interface greenhouse gas flux monitoring device and a measurement method of the present invention; Figure 7 It is a side view of a fixing plate provided in an embodiment of a sediment-water interface greenhouse gas flux monitoring device and a metering method of the present invention.

[0023] The markings in the figure are: 1. Gas and water monitoring box; 2. Gas monitoring box; 3. Gas collection hole; 4. Water outlet; 5. Buckle; 6. Slide rail; 7. Fixed plate; 8. Pull rod outlet; 9. Piston; 10. Pull rod; 11. Support plate; 12. PTFE membrane; 13. One-way permeable geomembrane; 14. Spring buckle; 15. Positioning strip; 16. Pull rope. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its application or use.

[0025] Embodiment 1: A sediment-water interface greenhouse gas flux monitoring device, such as Figure 1-Figure 5 As shown, it includes an air-water monitoring box 1 and a gas monitoring box 2, which are installed on the same slide rail 6 through a sliding connector and controlled by a buckle 5, the air-water monitoring box 1 and the gas monitoring box 2 are hollow and connected to the bottom with a fixing device for fixing the air-water monitoring box 1 and the gas monitoring box 2, the air-water monitoring box 1 and the gas monitoring box 2 are provided with a filtering structure for filtering the water and gas entering the air-water monitoring box 1 and the gas monitoring box 2, the gas monitoring box 2 is provided with an exhaust structure for exhausting the gas entering the gas monitoring box 2, and the outer wall of the gas monitoring box 2 is connected to the gas collection structure The gas-water monitoring box 1 is provided with a water outlet 4 on its side. By placing the gas-water monitoring box 1 and three gas monitoring boxes 2 mounted on the slide rail 6 into water and adjusting the positions of the gas-water monitoring box 1 and the three gas monitoring boxes 2 on the slide rail 6 according to the water depth, accurate field in-situ collection of gas at the underwater sediment-water interface at any depth can be achieved. Three gas monitoring boxes 2 can be set up to collect gas samples in different time periods as needed. The operation is convenient and the feasibility is high. The gas diffusion flux and the bubbling flux can be distinguished. When collecting gas samples, it is only necessary to pull the exhaust structure to send the collected gas into the air bag, and the sampling accuracy is greatly improved.

[0026] The fixing device includes a control structure and a movable fixing plate 7, and the fixing plate 7 is adjustably connected to the gas monitoring box 2 through the control structure. When the entire device enters the water body, the fixing plate 7 is not opened, the device is sealed, and is not affected by various external conditions.

[0027] The filtering structure includes a filter membrane and a support plate 11. Two support plates 11 are clamped on both sides of the filter membrane. The filter membrane includes a PTFE membrane 12 and a one-way permeable geomembrane 13. The filter membrane in the gas monitoring box 2 is a PTFE mold, and the filter membrane in the gas-water monitoring box 1 is a one-way permeable geomembrane 13. Impurities in the sediment are filtered through the filter membrane. The PTFE mold and the one-way permeable geomembrane 13 are used respectively according to the different things that need to be collected in the box.

[0028] The exhaust structure includes a pull rod 10 and a piston 9. The piston 9 is installed inside the gas monitoring box 2. The piston 9 is connected to the pull rod 10. The pull rod 10 passes through the gas monitoring box 2. By pulling the pull rod 10, the piston 9 is driven to collect the gas inside the gas-water monitoring box 1 into the gas collection structure for easy control.

[0029] The gas collection structure is an air bag, and a gas collection hole 3 is provided on the side wall of the gas monitoring box 2. The air bag is connected to the gas monitoring box 2 through the gas collection hole 3, so as to facilitate the collection of the gas to be detected.

[0030] An oil layer is applied at the connection of the fixed plate 7, an oil layer is applied at the hole on the side wall of the gas-water monitoring box 1 through the pull rod 10, and an oil layer is applied at the gas collection hole 3 on the side wall of the gas monitoring box 2 to ensure the sealing of the entire device during the collection process.

[0031] like Figure 6~Figure 7 As shown, the control structure includes a spring buckle 14, a locking strip 15 and a pull rope 16. The spring buckle 14 is arranged in the middle of the fixed plate 7, the locking strip 15 is arranged on the side of the fixed plate 7, and the spring buckle is connected to the pull rope 16. After the device sinks, the pull rope 16 is pulled to open the spring buckle 14, and the fixed plate 7 naturally droops and is locked by the locking strip 15 and inserted vertically.

[0032] Embodiment 2: Based on Example 1, an implementation method of a sediment-water interface greenhouse gas flux monitoring device and a measurement method is provided: like Figure 1 to Figure 7 As shown, this is achieved through a sediment-water interface greenhouse gas flux monitoring device. Adjust the length of the slide rail 6 according to the water depth, and install the gas-water monitoring box 1 and the three gas monitoring boxes 2 on the slide rail 6 through the buckle 5; Slowly put the whole device into the water, and when the device is close to the bottom of the water, manipulate the fixing device to vertically insert it into the sediment to fix the whole device; The gas sampling structure is used to collect atmospheric samples at 0.5 m above the water surface at the site, where the greenhouse gas concentration is recorded as C0; When the bottom of the device coincides with the sediment-water interface, the gas and water collection begins, and the starting time T0 is recorded. The water gradually passes through the filter structure into the gas and water monitoring box 1, and the gas generated by the sediment in the coverage area of ​​the gas monitoring box 2 passes through the filter structure and enters the three gas monitoring boxes 2 respectively; After the collection period expires, the buckle is adjusted to allow the gas-water monitoring box 1 and the gas monitoring box 2 to slide up and down on the slide rail, and the rope connected to the gas-water monitoring box 1 and the gas monitoring box 2 can be pulled to take out the gas-water monitoring box 1 or the gas monitoring box 2; At the sampling time T 2-1 , T 2-2 and T 2-3When the three gas monitoring boxes 2 are taken out in sequence, the gas in the monitoring boxes is pushed into the gas collection structure through the exhaust structure; At the end of sampling T 2-3 The gas-water monitoring box 1 is taken out simultaneously, and the water sample in the box is sent into the collection bottle by using a pump to complete the whole sampling process.

[0033] The laboratory gas chromatograph was used to measure the collected atmospheric samples C0 and the greenhouse gas concentration C in the three gas monitoring boxes 2. 2-1 , C 2-2 and C 2-3 ; Calculate the greenhouse gas diffusion flux F at the sediment-water interface in the three gas monitoring boxes 2 respectively 2-1 、F 2-2 and F 2-3 , the calculation formula is as follows: ; ; ; Wherein, V is the volume of a single gas monitoring box 2; A is the bottom area of ​​a single gas monitoring box 2; C 2-1 , C 2-2 and C 2-3 are the gas concentration differences before and after the sample collection in the three gas monitoring boxes 2, respectively, with the atmospheric concentration as the starting concentration C0; T 2-1 , T 2-2 and T 2-3 The time intervals for collecting samples from the three gas monitoring boxes 2 respectively; Take F 2-1 、F 2-2 and F 2-3 The arithmetic mean of can be used as the average value of greenhouse gas diffusion flux F2 at the sediment-water interface at the monitoring point, and the formula is: ;

[0034] The greenhouse gases in the water sample collected in the gas-water monitoring box 1 are collected by the headspace method, and the concentrations thereof are determined by gas chromatography; ; ;

[0035] In the formula, C wThe concentration of dissolved gas in water sample; C1 is the gas concentration measured after headspace equilibrium; C0 is the atmospheric background concentration; V0 is the headspace air volume / L; V1 is the water sample volume used for headspace measurement / L; R is the universal gas constant; T is the water temperature / K; K0 is the gas solubility coefficient; A1, A2, and A3 are constants.

[0036] Calculate the total greenhouse gas flux F1 entering the gas-water monitoring box 1 through diffusion and bubbling at the bottom of the gas-water monitoring box 1. The formula is:

[0037] Where, V is the volume of the gas-water monitoring box 1; A is the bottom area of ​​the gas-water monitoring box 1; C w The concentration of dissolved gas in the water of the gas-water monitoring box 1 sample; T 2-3 The time interval for collecting samples from the gas and water monitoring box 1.

[0038] Calculate the average time-period bubbling flux F of greenhouse gases at the sediment-water interface at this point 2-1泡 、F 2-2泡 and F 2-3泡 and the total average bubbling flux F 1泡 , the formula is ; ; ; .

[0039] Different from the first embodiment, the greenhouse gas concentrations in the three gas monitoring boxes 2 can be obtained during the monitoring process, and different gas monitoring boxes 2 can collect the concentrations of greenhouse gases in the water body at different times, so that the present invention can achieve continuous collection and the sampling calculation results are relatively accurate.

[0040] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only used to explain the relative position relationship, movement, etc. between the components in a certain posture. If the specific posture changes, the directional indication will also change accordingly. It is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application.

[0041] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0042] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A sediment-water interface greenhouse gas flux monitoring device, characterized in that: It comprises a gas-water monitoring box (1) and a gas monitoring box (2); The gas-water monitoring box (1) and the gas monitoring box (2) are mounted on the same slide rail (6) via a sliding connection and are controlled by a buckle (5); the gas-water monitoring box (1) and the gas monitoring box (2) are hollow and have a fixing device for fixing the gas-water monitoring box (1) and the gas monitoring box (2) connected to their bottom surfaces; The gas-water monitoring box (1) and the gas monitoring box (2) are provided with a filtering structure for filtering water and gas entering the gas-water monitoring box (1) and the gas monitoring box (2); the gas monitoring box (2) is provided with an exhaust structure for exhausting gas entering the gas monitoring box (2); the outer wall of the gas monitoring box (2) is connected to a gas collection structure; and a water outlet (4) is provided on the side of the gas-water monitoring box (1).

2. The sediment-water interface greenhouse gas flux monitoring device according to claim 1, characterized in that: The fixing device comprises a control structure and a movable fixing plate (7), and the fixing plate (7) is adjustably connected to the gas monitoring box (2) via the control structure.

3. The sediment-water interface greenhouse gas flux monitoring device according to claim 1, characterized in that: The control structure comprises a spring buckle (14), a locking strip (15) and a pull rope (16); the spring buckle (14) is arranged in the middle of the fixing plate (7), the locking strip (15) is arranged on the side of the fixing plate (7), and the spring buckle (14) is connected to the pull rope (16).

4. The sediment-water interface greenhouse gas flux monitoring device according to claim 1, characterized in that: The filtering structure comprises a filter membrane and a support plate (11), wherein two support plates (11) are clamped on both sides of the filter membrane.

5. The sediment-water interface greenhouse gas flux monitoring device according to claim 3, characterized in that: The filter membrane comprises a PTFE membrane (12) and a one-way permeable geomembrane (13); the filter membrane in the gas monitoring box (2) is a PTFE membrane, and the filter membrane in the gas-water monitoring box (1) is a one-way permeable geomembrane (13).

6. The sediment-water interface greenhouse gas flux monitoring device according to claim 2, characterized in that: The exhaust structure comprises a pull rod (10) and a piston (9), wherein the piston (9) is installed inside the gas monitoring box (2), the piston (9) is connected to the pull rod (10), and the pull rod (10) passes through the gas monitoring box (2).

7. The sediment-water interface greenhouse gas flux monitoring device according to claim 6, characterized in that: The gas collection structure is an air bag, a gas collection hole (3) is provided on the side wall of the gas monitoring box (2), and the air bag is connected to the gas monitoring box (2) via the gas collection hole (3).

8. The sediment-water interface greenhouse gas flux monitoring device according to claim 7, characterized in that: An oil layer is applied to the connection of the fixing plate (7), an oil layer is applied to the hole on the side wall of the gas-water monitoring box (1) through which the pull rod (10) passes, and an oil layer is applied to the gas sampling hole (3) on the side wall of the gas monitoring box (2).

9. A method for measuring greenhouse gas flux at a sediment-water interface, implemented by the sediment-water interface greenhouse gas flux monitoring device according to any one of claims 1 to 8, characterized in that: The following steps are involved: The length of the slide rail (6) is adjusted according to the water depth, and the gas-water monitoring box (1) and the gas monitoring box (2) are mounted on the slide rail (6) by means of a buckle (5); The entire device is slowly placed into the water, and when the device is close to the bottom of the water, the fixing device is manipulated to vertically insert into the sediment to fix the entire device; The gas sampling structure is used to collect atmospheric samples on the water surface at the site, wherein the greenhouse gas concentration is recorded as C0; When the bottom of the device coincides with the sediment-water interface, gas and water collection begins, and the starting time T0 is recorded. The water gradually passes through the filter structure and enters the gas and water monitoring box (1). The gas generated by the sediment in the area covered by the gas monitoring box (2) passes through the filter structure and enters the three gas monitoring boxes (2) respectively. After the collection period expires, the buckle (5) is adjusted so that the gas-water monitoring box (1) and the gas monitoring box (2) can slide up and down on the slide rail (6), and a single gas-water monitoring box (1) or gas monitoring box (2) can be taken out by pulling the rope connected to the gas-water monitoring box (1) and the gas monitoring box (2); At the sampling time T 2-1 、T 2-2 and T 2-3 When the three gas monitoring boxes (2) are taken out in sequence, the gas in the monitoring boxes is pushed into the gas collection structure through the exhaust structure; At the end of sampling T 2-3 The gas-water monitoring box (1) is taken out simultaneously, and the water sample in the box is sent into the collection bottle by using a pump, thereby completing the entire sampling process; The collected atmospheric sample C0 and the greenhouse gas concentration C in the three gas monitoring boxes (2) are measured by a laboratory gas chromatograph. 2-1 , C 2-2 and C 2-3 ; Calculate the greenhouse gas diffusion flux F at the sediment-water interface in the three gas monitoring boxes (2) respectively 2-1 、F 2-2 and F 2-3 , the calculation formula is as follows: ； ； ； Wherein, V is the volume of a single gas monitoring box (2); A is the bottom area of ​​a single gas monitoring box (2); C 2-1 , C 2-2 and C 2-3 are the gas concentration differences before and after sample collection in the three gas monitoring boxes (2), with the atmospheric concentration being taken as the starting concentration C0; T 2-1 , T 2-2 and T 2-3 are the time intervals for collecting samples from the three gas monitoring boxes (2); Take F 2-1 、F 2-2 and F 2-3 The arithmetic mean of can be used as the average value of greenhouse gas diffusion flux F2 at the sediment-water interface at the monitoring point, and the formula is: ； The greenhouse gases in the water sample collected in the gas-water monitoring box (1) are collected by the headspace balance method, and the concentrations thereof are determined by gas chromatography; ； Where, C w The concentration of dissolved gas in water sample; C1 is the gas concentration measured after headspace equilibrium; C0 is the atmospheric background concentration; V0 is the headspace air volume / L; V1 is the water sample volume used for headspace measurement / L; R is the universal gas constant; T is the water temperature / K; K0 is the gas solubility coefficient; A1, A2, A3 are constants; The total greenhouse gas flux F1 entering the gas-water monitoring box (1) through diffusion at the bottom of the gas-water monitoring box (1) and bubbling is calculated using the formula: ; Wherein, V is the volume of the gas-water monitoring box (1); A is the bottom area of ​​the gas-water monitoring box (1); C w The concentration of dissolved gas in the water of the gas-water monitoring box (1) sample; T 2-3 The time interval for collecting samples from the air and water monitoring box (1); Calculate the average time-period bubbling flux F of greenhouse gases at the sediment-water interface at this point 2-1泡 、F 2-2泡 and F 2-3泡 and the total average bubbling flux F 1泡 , the formula is: ； ； ； 。

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