A sampling device for collecting greenhouse gases of different water layers and depths in situ by headspace

Abstract

The application discloses a sampling device for collecting different water layers and depth greenhouse gases in situ, which comprises a collecting device, the collecting device comprising a collector, a gas collection cover, a plurality of traction ropes and a sealing disc, the gas collection cover being connected with a fixing device, a water inlet and outlet and a gas inlet and outlet being arranged on the collector, a water inlet and outlet pipe and a gas inlet and outlet pipe being arranged on the top wall of the gas collection cover and being communicated with the inner cavity of the gas collection cover, the gas inlet and outlet pipe being communicated with the gas inlet and outlet, the water inlet and outlet pipe being communicated with the water inlet and outlet, a through hole being symmetrically arranged on the side wall of the gas collection cover, the sealing disc being arranged in the gas collection cover, one end of the traction rope being respectively arranged through the through hole and being connected with the sealing disc, two traction ropes being symmetrically arranged and being respectively fixed with a sealing ball at different distances from the outer side wall of the gas collection cover, the distance between the sealing ball located on the same side of the central axis of the gas collection cover and the outer side wall of the gas collection cover being the same. The sampling device can accurately collect all greenhouse gases released in the bottom mud in the covering range without disturbing the bottom mud under water.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of natural ecological system greenhouse gas sampling, and particularly relates to a sampling device for collecting greenhouse gases at different water layers and depths by in-situ headspace method. BACKGROUND

[0002] In recent years, with the development of economy, global climate change is severe. With the increasing prominence of global warming, more and more attention is paid to greenhouse gas emissions, among which carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) are the three most important greenhouse gases. Freshwater ecosystems, especially freshwater aquaculture water bodies, are important sources of CH4 and N2O production and emission. High-density aquaculture brings a large amount of organic input, which accumulates in the sediment and undergoes biogeochemical cycling processes, producing a large amount of greenhouse gases such as CH4 and N2O. CH4 and N2O are mainly produced by microbial metabolism in the sediment, and these gases are then released from the sediment-water interface to the water-air interface and emitted to the atmosphere through molecular diffusion and bubbling. The release of greenhouse gases from the sediment to the water will inevitably change the emission amount due to changes in environmental factors, so more systematic and accurate research on the concentration changes and emission characteristics of greenhouse gases at different depths in the process from production in the sediment to release into the atmosphere will be beneficial to the study of the influence of changes in different factors in the water body on greenhouse gas emissions and provide a basis for identifying carbon reduction space and low carbon emission.

[0003] The most commonly used methods for collecting water body greenhouse gases in current research are static chamber method and inverted funnel method. These two methods are limited to collecting greenhouse gases at a single interface and cannot collect greenhouse gases at different water layers. The inverted funnel method has poor response to a small amount of bubbling, and long-term collection in water will cause the gas to dissolve in water, greatly affecting the accuracy of collecting greenhouse gases.

[0004] Traditional sediment bubbling flux collection devices either directly configure a greenhouse gas detection device in the gas collection hood and directly measure when the bubbling reaches a certain level, or use a drainage gas collection method to collect on the water surface. Both of these two forms have the following defects: 1. There is a response threshold for the amount of greenhouse gas emissions. The former requires a certain amount of released greenhouse gas to be detected, and the latter cannot cause trace amounts of bubbles to enter the drainage bottle due to mechanical structure and other reasons, thereby affecting the accuracy of greenhouse gas monitoring; 2. Both methods are to directly immerse the gas collection hood in the water for collection and monitoring, and the bubbles of the latter need to enter the drainage gas collection bottle on the water surface through the water pipe. The water body has a water storage of greenhouse gases, which will cause the loss of trace amounts of bubbling during the collection process, thereby affecting the detection accuracy. SUMMARY

[0005] To solve the above technical problems, the application provides a sampling device for collecting greenhouse gases in different water layers and depths by in-situ headspace method, which can avoid disturbing the bottom mud underwater, create an in-situ headspace environment, reduce the dissolved amount of greenhouse gases in water during the collection process, and collect all the headspace gas back into the collector after the collection is completed, so that the mechanical structure does not hinder the collection of trace greenhouse gases, accurately collects all the greenhouse gases released from the bottom mud in the coverage range, and can adjust the depth through the gas cover connecting rod to collect greenhouse gases released in different water layers, which has strong practicability and application value.

[0006] To achieve the above technical purposes, the application adopts the following technical solutions:

[0007] A sampling device for collecting greenhouse gases in different water layers and depths by in-situ headspace method, comprising a collection device, which is detachably connected with the edge of a ship body through a fixing device; the collection device comprises a collector, a gas collector, a plurality of traction ropes and a sealing disc, the gas collector is connected with the fixing device, a water inlet and outlet and a gas inlet and outlet are arranged on the collector, three-way valves are respectively connected with the water inlet and outlet and the gas inlet and outlet, a water inlet and outlet pipe and a gas inlet and outlet pipe are arranged on the top wall of the gas collector and communicate with the inner cavity of the gas collector, the gas inlet and outlet pipe communicates with the three-way valve at the gas inlet and outlet through a pipe fitting, and the water inlet and outlet pipe communicates with the three-way valve at the water inlet and outlet; a plurality of through holes are symmetrically arranged on the side wall of the gas collector, the sealing disc is arranged in the gas collector, one end of each of the plurality of traction ropes passes through a through hole and is connected with the sealing disc, two traction ropes symmetrically arranged are respectively fixed with a sealing ball at different distances from the outer side wall of the gas collector, the distance between the sealing ball on the traction rope located on the same side of the central axis of the gas collector and the outer side wall of the gas collector is the same, and a sealing gasket is arranged on the outer circumferential side of the through hole; the collector comprises a gas cavity, a water cavity, a linkage rod and two pistons, the two pistons are respectively fixed at the two ends of the linkage rod and are respectively arranged in the gas cavity and the water cavity in a sliding sealing manner, the water inlet and outlet is arranged on the lower part of the side wall of the water cavity, and the gas inlet and outlet is arranged on the lower part of the side wall of the gas cavity.

[0008] Further, a sealing ring 10 is arranged at the abutting position between the sealing disc and the inner side wall of the gas collector.

[0009] Further, the fixing device comprises a gas collector fixing frame, at least one gas collector connecting rod, a connecting arm and two fixing rods, the lower end of the gas collector fixing frame is fixedly connected with the upper part of the outer side wall of the gas collector, the top of the gas collector fixing frame is connected with the lower end of the gas collector connecting rod, the connecting arm is fixed to the upper part of the gas collector connecting rod and is arranged perpendicularly to the gas collector connecting rod, the two fixing rods are fixed to one side of the connecting arm away from the gas collector connecting rod in an up-down interval, screw holes are oppositely arranged on the ends of the two fixing rods away from the connecting arm, and the fixing device is connected with the edge of the ship body through fixing bolts penetrating the screw holes of the fixing rods and fixing clamps.

[0010] Further, a scale is arranged on the gas hood connecting rod.

[0011] Further, external threads are arranged on the side walls of the two ends of the gas hood connecting rod, and the adjacent ends of two adjacent gas hood connecting rods are connected through nuts.

[0012] Further, the collecting device further comprises a traction rope collecting ring and a traction rope handle, the traction rope collecting ring is sleeved on the traction rope, and the traction rope handle is connected with the upper end of the traction rope.

[0013] Further, the distance between the sealing balls on the two traction ropes and the outer side wall of the gas hood is 5 cm and 10 cm respectively.

[0014] Further, the gas hood comprises an upper conical part and a lower cylindrical part, and the through hole is arranged on the side wall of the upper conical part.

[0015] The sampling device for collecting greenhouse gases of different water layers and depths by in-situ headspace method of the present application can form a headspace environment in the gas hood without disturbing the bottom mud, so the following effects can be achieved: during the collection process, the gases released by the bottom mud are temporarily stored in the headspace, avoiding the loss of the dissolved greenhouse gases due to the long time of the greenhouse gases in the water, so that the release amount of the greenhouse gases of the bottom mud can be more accurately calculated; due to the existence of the headspace environment, the gases in the headspace can be completely sucked back after the collection is completed, so that no matter how small the amount of greenhouse gases released by the bottom mud is, it can be collected, and the missing of the collected amount due to the small release amount or the blocking of the mechanical structure will not occur; by adjusting the monitored depth, the change of the amount of greenhouse gases at different depths during the release process of the greenhouse gases from the mud-water interface to the water-gas interface can be analyzed. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is the front view of the sampling device for collecting greenhouse gases of different water layers and depths by in-situ headspace method of the present application;

[0017] Figure 2 is the front view of the collector of the present application;

[0018] Figure 3 is the sectional view of the collector of the present application;

[0019] Figure 4 is the connection structure diagram of the sealing ball, the sealing gasket and the sealing ring of the present application.

[0020] In the diagram, 1-collector, 2-linkage rod, 3-inlet / outlet water port, 4-inlet / outlet air port, 5-inlet / outlet water pipe, 6-inlet / outlet air pipe, 7-sealing ball, 8-sealing gasket, 9-sealing disc, 10-sealing ring, 11-gas collection hood, 12-gas collection hood fixing frame, 13-traction rope, 14-traction rope gathering ring, 15-traction rope handle, 16-gas collection hood connecting rod, 17-fixing rod, 18-connecting arm, 19-fixing bolt, 20-fixing clamp, 21-three-way valve, 22-air chamber, 23-water chamber, 24-linkage rod, 25-piston. Implementation

[0021] The device system of the present invention will be further described below with reference to specific implementation examples and accompanying drawings.

[0022] like Figures 1-4 As shown, an in-situ headspace sampling device for collecting greenhouse gases at different water layers and depths includes a sampling device detachably connected to the edge of a ship via a fixing device. The sampling device comprises a collector 1, a gas collection hood 11, multiple towing ropes 13, towing rope retraction rings 14, towing rope handles 15, and a sealing disc 9. The gas collection hood 11 is connected to the fixing device. The collector 1 is provided with water inlet / outlet 3 and air inlet / outlet 4. A three-way valve 21 is connected to each of the following locations: A water inlet / outlet pipe 5 and an air inlet / outlet pipe 6 are provided on the top wall of the gas collecting hood 11, communicating with its inner cavity. The air inlet / outlet pipe 6 is connected to the three-way valve 21 at the air inlet / outlet 4 via a fitting, and the water inlet / outlet pipe 5 is connected to the three-way valve 21 at the water inlet / outlet 3. Multiple through holes are symmetrically opened on the side wall of the gas collecting hood 11. The sealing disc 9 is placed inside the gas collecting hood 11. The traction rope gathering ring 14 is sleeved on the traction rope 13. The traction rope handle 1... 5 is connected to the upper end of the traction rope 13. One end of each of the multiple traction ropes 13 passes through a through hole and connects to the sealing disc 9. A sealing ring 10 is provided at the contact point between the sealing disc 9 and the inner wall of the gas collection hood 11. Two symmetrically arranged traction ropes 13 are fixed with a sealing ball 7 at different distances from the outer wall of the gas collection hood 11. The distances between the sealing ball 7 on the two symmetrically arranged traction ropes 13 and the outer wall of the gas collection hood 11 are 5cm and 10cm, respectively, and they are located on the central axis of the gas collection hood 11. The distance between the sealing ball 7 on the same side of the traction rope 13 and the outer wall of the gas collection hood 11 is the same, and a sealing gasket 8 is provided on the outer periphery of the through hole; the collector 1 includes an air chamber 22, a water chamber 23, a linkage rod 24 and two pistons 25. The two pistons 25 are respectively fixed at both ends of the linkage rod 24 and are respectively slidably sealed in the air chamber 22 and the water chamber 23. The water inlet and outlet 3 are located on the lower part of the side wall of the water chamber 23, and the air inlet and outlet 4 are located on the lower part of the side wall of the air chamber 22.

[0023] The fixing device comprises a hood fixing frame 12, at least one hood connecting rod 16, a connecting arm 18 and two fixing rods 17, the lower end of the hood fixing frame 12 is fixedly connected with the upper outer side wall of the hood 11, the top of the hood fixing frame 12 is connected with the lower end of the hood connecting rod 16, the connecting arm 18 is fixed to the upper part of the hood connecting rod 16 and is arranged perpendicularly to the hood connecting rod 16, the two fixing rods 17 are fixed to the side of the connecting arm 18 away from the hood connecting rod 16 in an up-down interval, screw holes are oppositely arranged at the ends of the two fixing rods 17 away from the connecting arm 18, and the fixing device is connected with the edge of the ship body through fixing bolts 19 and fixing clamps 20 arranged in the screw holes of the fixing rods 17; a scale is arranged on the hood connecting rod 16, external threads are arranged on the side walls of the two ends of the hood connecting rod 16, and the adjacent ends of the adjacent two hood connecting rods 16 are connected through nuts.

[0024] The hood 11 comprises an upper conical part and a lower cylindrical part, and the through hole is arranged on the side wall of the upper conical part.

[0025] The use method of the sampling device is as follows:

[0026] Firstly, the fixing device is fixed on the edge of the ship body through the fixing clamps 20 and the fixing bolts 19; the hood connecting rods 16 are equipped with multiple rods as required, each rod is 1 m long, the rod body is marked with a scale and the two ends are provided with threads for splicing the hood connecting rods 16; the overall height of the hood fixing frame 12 is 0.5 m, and the hood connecting rod 16 is connected with the hood fixing frame 12 in water according to the water depth;

[0027] Secondly, after the water cavity of the collector is filled with water, the water inlet and outlet pipe and the water inlet and outlet pipe are connected, the three-way valve is communicated, the water in the water cavity is discharged by pulling the connecting rod, and the three-way valve is closed after water is sucked into the air cavity, and the purpose of this step is to remove the air in the water inlet and outlet pipe and the water inlet and outlet pipe; thirdly, after the water cavity is filled with water, the linkage rod 24 of the collector 1 is pulled before collection, and high-purity nitrogen gas is extracted from the gas bag provided with high-purity nitrogen gas through the water inlet and outlet port 4; at this time, a certain volume of water still exists in the water cavity, and the connection collector starts to make headspace at this time;

[0028] Thirdly, the sealing disc 9 is tightly attached to the sealing ring 10 by pulling the traction rope handle 15 before making headspace, a closed space is formed at the top of the hood 11, then high-purity nitrogen gas is punched into the hood 11 through the water inlet and outlet pipe 6 by pulling the linkage rod 2, the linkage rod 2 simultaneously sucks the water of the same volume into the collector 1 through the water inlet and outlet pipe 5 from the other side, a fixed volume of headspace is formed, and the volume in the air cavity is 0 ml after the headspace is made.

[0029] Fourth, release the traction rope handle 15, and the sealing disc 9 slowly sinks due to gravity. The traction rope 13 connecting the two ends of the sealing disc 9 has a sealing ball 7 at 5cm and 10cm respectively. Due to the gravity traction of the sealing disc 9, the sealing ball 7 is tightly combined with the sealing gasket 8, so that the gas collection hood 11 forms a top-space sealed environment.

[0030] Fifth, after a period of time, all the headspace gas is extracted from the collector 1 and injected into the gas bag for analysis of greenhouse gas emissions. Specifically, after a certain period of time, the linkage lever 24 of the collector 1 is pulled to extract the gas in the headspace into the gas chamber 22. At the same time, the water in the water chamber 23 is discharged into the gas collection hood 11. When the water is extracted from the gas chamber 22, it is considered that all the gas in the headspace has been completely extracted.

[0031] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A sampling device for in-situ headspace collection of different water layers and depths of greenhouse gases, characterized in that, The sampling device comprises a collecting device detachably connected with the edge of the ship body through a fixing device; the collecting device comprises a collector, a gas collecting cover, a plurality of traction ropes and a sealing disc; the gas collecting cover is connected with the fixing device; a water inlet and outlet and a gas inlet and outlet are arranged on the collector; a three-way valve is connected with the water inlet and outlet and the gas inlet and outlet respectively; a water inlet and outlet pipe and a gas inlet and outlet pipe which communicate with the inner cavity of the gas collecting cover are arranged on the top wall of the gas collecting cover; the gas inlet and outlet pipe communicates with the three-way valve at the gas inlet and outlet through a pipe fitting; the water inlet and outlet pipe communicates with the three-way valve at the water inlet and outlet; a plurality of through holes are symmetrically arranged on the side wall of the gas collecting cover; the sealing disc is arranged in the gas collecting cover; one end of each of the plurality of traction ropes passes through a through hole and is connected with the sealing disc; two traction ropes symmetrically arranged are fixed with a sealing ball at different distances from the outer side wall of the gas collecting cover; the distance between the sealing ball on the traction rope located on the same side of the central axis of the gas collecting cover and the outer side wall of the gas collecting cover is the same; a sealing gasket is arranged on the outer circumferential side of the through hole.

2. The sampling device for in-situ headspace sampling of different water layers and depths of greenhouse gases according to claim 1, characterized in that, A sealing ring is arranged at the abutting position between the sealing disc and the inner side wall of the gas collecting cover.

3. The sampling device for in-situ headspace collection of different water layers and depth greenhouse gases according to claim 1, wherein, The fixing device comprises a gas collecting cover fixing frame, at least one gas collecting cover connecting rod, a connecting arm and two fixing rods; the lower end of the gas collecting cover fixing frame is fixedly connected with the upper outer side wall of the gas collecting cover; the top of the gas collecting cover fixing frame is connected with the lower end of the gas collecting cover connecting rod; the connecting arm is fixed to the upper part of the gas collecting cover connecting rod and is arranged perpendicularly to the gas collecting cover connecting rod; the two fixing rods are fixed to one side of the connecting arm away from the gas collecting cover connecting rod at intervals; screw holes are arranged on the ends of the two fixing rods away from the connecting arm; the fixing device is connected with the edge of the ship body through fixing bolts and fixing clamps penetrating the screw holes of the fixing rods.

4. The sampling device for in-situ headspace sampling of different water layers and greenhouse gases at different depths according to claim 3, characterized in that, A scale is arranged on the gas collecting cover connecting rod.

5. The sampling device for in-situ headspace sampling of different water layers and depths of greenhouse gases according to claim 4, characterized in that, External threads are arranged on the side walls of the two ends of the gas collecting cover connecting rod; adjacent ends of adjacent two gas collecting cover connecting rods are connected through nuts.

6. The sampling device for in-situ headspace collection of different water layers and depth greenhouse gases according to claim 1, wherein, The collecting device further comprises a traction rope collecting ring and a traction rope handle; the traction rope collecting ring is sleeved on the traction rope; the traction rope handle is connected with the upper end of the traction rope.

7. The sampling device for in-situ headspace collection of different water layers and depth greenhouse gases according to claim 1, wherein, The distances between the sealing balls on the two traction ropes symmetrically arranged and the outer side wall of the gas collecting cover are 5 cm and 10 cm respectively.

8. The sampling device for in-situ headspace collection of different water layers and depth greenhouse gases according to claim 1, wherein, The gas collecting cover comprises an upper conical part and a lower cylindrical part; the through holes are arranged on the side wall of the upper conical part.

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