Device and method for rapidly detecting methane production and consumption rate of water body

Abstract

The invention discloses a device and method for rapidly detecting the methane production and consumption rate of a water body, the device comprises a gas-liquid mixing device, the gas-liquid mixing device comprises a fixed column and a connecting pipe wound on the fixed column, the two ends of the connecting pipe are connected with purging tanks, and the movable ends of the purging tanks are connected with the output end of a peristaltic pump and the output end of a gas cylinder; the top end of the other purging tank is connected with a greenhouse gas analyzer, and the bottom end is provided with a water outlet. The methane concentration of the water body treated by the water-gas separation device is reduced, and the variation of methane can be better measured in a shorter time. The experimental method is simple, the operation is simple, an in-situ test can be carried out, and the production rate, the net production rate and the net oxidation rate of methane in a water body can be measured in a short time.

Description

Technical Field

[0001] The invention relates to the technical field of ecological monitoring, and in particular to a device and method for rapidly detecting the methane production and consumption rate of a water body. Background Art

[0002] At present, the main detection technologies for changes in methane concentration in water bodies include: static headspace balance method, dynamic headspace balance method, multiple headspace balance method, etc. The principle of the static headspace balance method is to take a sealed bottle with a certain volume of gas left on the top and a water sample to be tested at the bottom. The sealed bottle is left to stand at a constant temperature for a period of time. During this process, the soluble or volatile gas in the liquid phase will slowly enter the gas phase until the gas in the two phases reaches a state of equilibrium, and a certain volume of headspace gas is taken for measurement. The principle of the dynamic headspace balance method is to complete the measurement after achieving equilibrium in the headspace gas of the water sample to be tested in a dynamic process. The principle of the multiple headspace balance method is to extract and measure the headspace gas of the sample multiple times at equal time intervals based on the ordinary headspace balance method. On the basis of the above methods, the production and consumption rate of methane in the water body can be measured by adding methane production and oxidation inhibitors to the water body. However, the above methods require a long measurement time, and the hourly methane production and consumption rate is on the order of ng / (L∙h). When the methane concentration is too high, it is impossible to accurately measure the methane production and consumption time in a short time. Summary of the invention

[0003] The technical problem to be solved by the present invention is that the method for measuring the change of methane concentration in water body is time-consuming and has low accuracy.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a device for quickly detecting the methane production and consumption rate of a water body, including a gas-liquid mixing device, the gas-liquid mixing device includes a fixed column and a connecting pipe wrapped around the fixed column, both ends of the connecting pipe are connected to a purge tank, the active end of the purge tank is connected to the output end of the peristaltic pump and the output end of the gas cylinder, the top of another purge tank is connected to a greenhouse gas analyzer, and a water outlet is arranged at the bottom.

[0005] Preferably, the output end of the gas cylinder is connected to the air inlet of the purge tank through a pipeline, and the air inlet is connected to the aeration stone through a pipeline.

[0006] Preferably, a capacity scale is provided on the purge tank.

[0007] Preferably, a vacuum filter and a valve are connected to the top pipe of the purge tank.

[0008] Preferably, the connecting pipe is spirally wound on the fixing column, the connecting pipe comprises a vertical pipe and a main pipe, and the airflow inlet end of the connecting pipe is connected to the bottom end of the spiral main pipe through the vertical pipe.

[0009] Preferably, the output end of the greenhouse gas analyzer is connected to a waste gas collection device.

[0010] Preferably, the water outlet is connected to a water outlet pipe with a U-shaped water seal.

[0011] Preferably, the water inlet of the peristaltic pump is connected to a water bag containing the water body to be tested.

[0012] A method for using a device for rapidly measuring the methane production and consumption rate of a water body comprises the following steps: Step 1: Preliminary preparation: prepare six 5L water bags, numbered 1, 2, 3, 4, 5, 6, modify the water bags, add a 6mm diameter hose, and install a switch at the end of the hose to control the water output. Divide into two groups, one group is the control group 1, 2, 3, and the other group is the experimental group 4, 5, 6; Step 2: Collect water samples, collect no less than 12L of water to be tested; Step 3: Purge the water-gas separation device, connect the water inlet of the peristaltic pump input end to the water body, start the peristaltic pump, the gas cylinder and the gas-liquid mixing device, control the gas outlet flow rate of the gas cylinder and the water outlet flow rate of the peristaltic pump, and collect the purged water body using a container; Step 4: Water sample subpackaging and processing: according to the volume of water in the experimental group water bags, use a balance to weigh the methane inhibitor, and match water bags 1 and 4, 2 and 5, 3 and 6. Take part of the purged water to fully disturb it and put it into water bags 1 and 4 respectively. Repeat the operation to pack it into water bags 2, 5, 3 and 6; Step 5: Water sample testing: select water bag No. 1 of the control group, connect the hose of the water bag to the water inlet, turn on the switch on the hose, start the gas cylinder, and test it through the greenhouse gas analyzer. Wait for 3-5 minutes. After the methane data is stable, record the average value of the stable data. After the end, turn off the switch on the hose, store the water bag under the required environmental conditions, record the start and end time of the measurement, repeat the test on six water bags, and obtain the initial methane concentration of the six water bags. The second round of testing begins one hour after the first water bag test, using the same method as the first round of testing. After the test, the methane concentration of six water bags one hour later is obtained. Step 6: First, subtract the first round of measurement value from the second round of measurement value of each water bag and divide it by one hour. The result of the control group is the methane production rate, which is recorded as ①②③ according to the water bag number. The result of the experimental group is the methane net oxidation rate, which is recorded as ④⑤⑥ according to the water bag number. Calculate ④-①, ⑤-②, ⑥-③, and get the three net methane production rate values ​​⑦, ⑧, and ⑨. Calculate the average of ①②③ to get the required methane production rate, calculate the average of ④⑤⑥ to get the net methane oxidation rate, and calculate the average of ⑦⑧⑨ to get the net methane production rate.

[0013] Preferably, the methane inhibitor is sodium 2-bromoethylsulfonate, and the concentration of sodium 2-bromoethylsulfonate is not less than 9 g / L when added.

[0014] The present invention provides a device and method for quickly detecting the methane production and consumption rate of a water body. After the water body is treated by a water-gas separation device, the methane concentration is reduced, and the change in methane can be better measured in a shorter time. The experimental method is simple, the operation is simple, and an in-situ test can be performed to measure the generation rate, net generation rate, and net oxidation rate of methane in the water body in a short time. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Figure 1 It is a schematic structural diagram of an embodiment of the present invention.

[0016] Figure 2 It is the conversion mark line between the measured value of the water-gas separation device and the actual value of the water body in the embodiment of the present invention.

[0017] Figure 3 This is a diagram of methane concentration and production and consumption rate in river stratified water bodies in an embodiment of the present invention.

[0018] Figure 4 The process flow chart of an embodiment of the present invention.

[0019] In the figure: 1. water inlet; 2. peristaltic pump; 3. gas cylinder; 4. air inlet; 5. aeration stone; 6. gas-liquid mixing device; 7. water outlet; 8. air outlet; 9. water bag; 10. greenhouse gas analyzer; 11. purge tank; 12. connecting pipe; 13. vacuum filter. DETAILED DESCRIPTION

[0020] like Figure 1-4 As shown, the present invention provides a device for quickly detecting the methane production and consumption rate of a water body, including a gas-liquid mixing device 6, the gas-liquid mixing device 6 includes a fixed column and a connecting pipe 12 wound around the fixed column, both ends of the connecting pipe 12 are connected to a purge tank 11, the movable end of the purge tank 11 is connected to the output end of the peristaltic pump 2 and the output end of the gas cylinder 3, the top of another purge tank 11 is connected to a greenhouse gas analyzer 10, and a water outlet 7 is arranged at the bottom.

[0021] The water in the water bag 9 is sucked into the purge tank 11 by the peristaltic pump 2, and the nitrogen is released through the gas cylinder 3 to purge the water in the purge tank 11. The methane gas generated during the purge enters the greenhouse gas analyzer 10 through the connecting pipe 12, and the methane concentration in the generated gas is detected by the greenhouse gas analyzer 10.

[0022] The greenhouse gas analyzer 10 is a picarro greenhouse gas analyzer.

[0023] like Figure 1 The output end of the gas cylinder 3 is connected to the air inlet 4 of the purge tank 11 through a pipeline, and the air inlet 4 is connected to the aeration stone 5 through a pipeline. The aeration stone 5 is cylindrical, and air outlet holes are evenly arranged on the outer circumference of the aeration stone 5. The nitrogen output from the gas cylinder 3 aerates and purges the water in the purge tank 11 through the aeration stone 5 to blow out the dissolved methane gas.

[0024] like Figure 1 As shown. The purge tank 11 is provided with a capacity scale. According to the volume of water in the purge tank 11, the gas output flow rate of the gas cylinder 3 is controlled, and corresponds to the methane gas concentration detected by the greenhouse gas analyzer 10. (The air intake and water intake are directly controlled to a fixed value through the gas valve and peristaltic pump, and the water gas input value basically does not need to be changed) like Figure 1 As shown. A vacuum filter 13 and a valve are connected to the top pipe of the purge tank 11. The moisture in the gas is filtered by the vacuum filter 13 to avoid affecting the greenhouse gas analyzer 10.

[0025] like Figure 1 As shown. The connecting pipe 12 is spirally wound on the fixed column, and the connecting pipe 13 includes a vertical pipe and a main pipe. The airflow and water inlet end of the connecting pipe 13 is connected to the bottom end of the spiral main pipe through the vertical pipe. After water enters the vertical pipe, since the bottom end of the main pipe is the water inlet end, part of the water will remain at the inner bottom of the main pipe, and then the connection between the main pipe and the vertical pipe can be disconnected to discharge the water in the connecting pipe 12. (Or: water and gas enter 12 from the purge tank 11 through the valve 13 and are fully mixed, and then enter the gas-liquid separation tank 14).

[0026] As a preferred embodiment of the present invention, the output end of the greenhouse gas analyzer 10 is connected to a waste gas collection device, which recovers and ignites the gas entering the greenhouse gas analyzer 10 .

[0027] like Figure 1 The water outlet 7 is connected to a water outlet pipe with a U-shaped water seal, so that the gas in the connecting pipe 12 can be prevented from being discharged from the pipe connected to the water outlet 7.

[0028] As a preferred embodiment of the present invention, the water inlet 1 of the peristaltic pump 2 is connected to a water bag 9 containing the water body to be tested.

[0029] A method for using a device for rapidly measuring the methane production and consumption rate of a water body comprises the following steps: Step 1: Preliminary preparation: prepare six 5L water bags 9, numbered 1, 2, 3, 4, 5, 6, modify the water bags 9, add a hose with a diameter of 6 mm, and add a switch at the end of the hose to control the water output. Divide into two groups, one group is the control group 1, 2, 3, and the other group is the experimental group 4, 5, 6; Step 2: Collect water samples, collect no less than 12L of water to be tested; Step 3: Purge the water-gas separation device, connect the water inlet 1 of the input end of the peristaltic pump 2 to the water body, start the peristaltic pump 2, the gas cylinder 3 and the gas-liquid mixing device 6, control the gas outlet flow rate of the gas cylinder 3 and the water outlet flow rate of the peristaltic pump 2, and collect the purged water body using a container; Step 4: Water sample subpackaging and processing: according to the volume of water in the experimental group water bags, use a balance to weigh the methane inhibitor, and match the water bags 9 of 1 and 4, 2 and 5, 3 and 6. Take part of the purged water to fully disturb it and put it into water bags 1 and 4 respectively. Repeat the operation to pack the water bags 2, 5, 3 and 6; Step 5: Water sample testing. Select water bag 9 No. 1 in the control group, connect the hose of water bag 9 to the water inlet 1, turn on the switch on the hose, start the gas cylinder 3, and test with the greenhouse gas analyzer 10. Wait for 3-5 minutes. After the methane data is stable, record the average value of the stable data. After the end, turn off the switch on the hose, store the water bag 9 under the required environmental conditions, record the start and end time of the measurement, repeat the test for six water bags 9, and obtain the initial methane concentration of the six water bags 9. The second round of testing begins one hour after the first water bag 9 is tested. The method is the same as the first round of testing. After the test, the methane concentration of the six water bags one hour later is obtained. The change in the two measurements of the water bag is calculated. It is also the sum of the net production rate and net oxidation rate of methane in the water body. A positive value means an increase in the methane concentration in the water body, and a negative value means a decrease in the methane concentration in the water body. The net oxidation rate is generally negative, the inhibitor inhibits the production of methane, and the methane in the water body is always oxidized. ; Step 6: First, subtract the first round of measurement value from the second round of measurement value of each water bag 9 and divide it by one hour. The result of the control group is the methane production rate, which is recorded as ①②③ according to the water bag number. The result of the experimental group is the methane net oxidation rate, which is recorded as ④⑤⑥ according to the water bag number. Calculate ④-①, ⑤-②, ⑥-③, and get the three net methane production rate values ​​⑦, ⑧, and ⑨. Calculate the average of ①②③ to get the required methane production rate, calculate the average of ④⑤⑥ to get the net methane oxidation rate, and calculate the average of ⑦⑧⑨ to get the net methane production rate.

[0030] The methane inhibitor is sodium 2-bromoethylsulfonate, and the concentration of sodium 2-bromoethylsulfonate is not less than 9 g / L when added.

Claims

1. A device for rapidly detecting the methane production and consumption rate of water bodies, characterized in that: The invention comprises a gas-liquid mixing device (6), the gas-liquid mixing device (6) comprising a fixed column and a connecting pipe (12) wound around the fixed column, both ends of the connecting pipe (12) are connected to a purge tank (11), the movable end of the purge tank (11) is connected to the output end of the peristaltic pump (2) and the output end of the gas cylinder (3), the top end of the other purge tank (11) is connected to a greenhouse gas analyzer (10), and the bottom end is provided with a water outlet (7).

2. A device for rapidly measuring the methane production and consumption rate of a water body as claimed in claim 1, characterized in that: The output end of the gas cylinder (3) is connected to the air inlet (4) of the purge tank (11) through a pipeline, and the air inlet (4) is connected to the aeration stone (5) through a pipeline.

3. A device for rapidly measuring the methane production and consumption rate of a water body as claimed in claim 1, characterized in that: The purge tank (11) is provided with a capacity scale.

4. A device for rapidly measuring the methane production and consumption rate of a water body as claimed in claim 1, characterized in that: A vacuum filter (13) and a valve are connected to the top pipe of the purge tank (11).

5. A device for rapidly measuring the methane production and consumption rate of a water body as claimed in claim 1, characterized in that: The connecting pipe (12) is spirally wound on the fixing column, and the connecting pipe (13) comprises a vertical pipe and a main pipe. The airflow inlet end of the connecting pipe (13) is connected to the bottom end of the spiral main pipe through the vertical pipe.

6. A device for rapidly measuring the methane production and consumption rate of a water body as claimed in claim 1, characterized in that: The output end of the greenhouse gas analyzer (10) is connected to a waste gas collection device.

7. A device for rapidly measuring the methane production and consumption rate of a water body as claimed in claim 1, characterized in that: The water outlet (7) is connected to a water outlet pipe with a U-shaped water seal.

8. A device for rapidly measuring the methane production and consumption rate of a water body as claimed in claim 1, characterized in that: The water inlet (1) of the peristaltic pump (2) is connected to a water bag (9) containing the water body to be tested.

9. A method for using a device for rapidly measuring the methane production and consumption rate of a water body as claimed in claim 1, characterized in that: The steps include: Step 1: Preliminary preparation: prepare six 5L water bags (9), numbered 1, 2, 3, 4, 5, 6, modify the water bags (9), add a hose with a diameter of 6 mm, and add a switch at the end of the hose to control the water output. Divide the water bags into two groups, one group is a control group 1, 2, 3, and the other group is an experimental group 4, 5, 6; Step 2: Collect water samples, collect no less than 12L of water to be tested; Step 3: purging the water-gas separation device, connecting the water inlet (1) of the input end of the peristaltic pump (2) to the water body, starting the peristaltic pump (2), the gas cylinder (3) and the gas-liquid mixing device (6), controlling the gas outlet flow rate of the gas cylinder (3) and the water outlet flow rate of the peristaltic pump (2), and collecting the purged water body using a container; Step 4: Water sample subpackaging and processing: according to the volume of water in the experimental group water bags, use a balance to weigh the methane inhibitor, and match the water bags (9) 1 and 4, 2 and 5, 3 and 6. Take part of the purged water to fully disturb it and put it into water bags 1 and 4 respectively. Repeat the operation to pack it into water bags 2, 5, 3 and 6; Step 5: Water sample testing. Select water bag No. 1 (9) of the control group, connect the hose of the water bag (9) to the water inlet (1), turn on the switch on the hose, start the gas cylinder (3), and perform testing using the greenhouse gas analyzer (10). Wait for 3-5 minutes. After the methane data stabilizes, record the average value of the data after stabilization. After the test is completed, turn off the switch on the hose, store the water bag (9) under the required environmental conditions, record the start and end time of the measurement, and repeat the test on six water bags (9) to obtain the initial methane concentrations of the six water bags (9). One hour after the first water bag (9) is tested, the second round of testing begins, using the same method as the first round of testing. After the test, the methane concentration of six water bags one hour later is obtained. Step 6: First, subtract the first round of measurement value from the second round of measurement value of each water bag (9) and divide it by the time of one hour. The result of the control group is the methane production rate, which is recorded as ①②③ according to the water bag number. The result of the experimental group is the methane net oxidation rate, which is recorded as ④⑤⑥ according to the water bag number. Calculate ④-①, ⑤-②, ⑥-③, and get the three values ​​of net methane production rate ⑦, ⑧, and ⑨. The average of ①②③ is the required methane production rate, the average of ④⑤⑥ is the net methane oxidation rate, and the average of ⑦⑧⑨ is the net methane production rate.

10. A method for using the device for rapidly measuring the methane production and consumption rate of water bodies as claimed in claim 9, characterized in that: The methane inhibitor is sodium 2-bromoethylsulfonate, and the concentration of sodium 2-bromoethylsulfonate is not less than 9 g / L when added.

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